FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
SENSOR AND ELECTRIC DEVICE WITH THE SENSOR
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
- 2 -
DESCRIPTION
TECHNICAL FIELD
[0001] This disclosure relates to a sensor to identify the type of corrosive gas present in
an environment and an electric device equipped with the sensor.5
BACKGROUND ART
[0002] In case an electric device is installed in an environment where any corrosive gas
is present, corrosion of the electric device may progress with time, inviting the risk of a
circuit board of the device being damaged by the corrosion. An example of the risk
may be breakage of metal wiring due to corrosion. To prevent such unwanted damage10
or breakage associated with corrosion, a technology has been proposed with an aim to
grasp the degree of corrosion progressing in electric devices in environments where
they are installed.
[0003] WO 2020/039611 (PTL 1) describes a corrosive environment monitoring
system directed to identifying what type of corrosive gas is present in an environment.15
This corrosive environment monitoring system is equipped with a corrosion sensor
structured with a passageway having a closed end on one side and an opening end on
the other side thereof. Part of the upper and lower surfaces or the left and right
surfaces of the opening is formed of a transparent substrate. A metal thin film is
formed on a surface of the transparent substrate that comes into contact with the20
corrosive gas flowing from the opening. The corrosion sensor can observe and
determine the degree of discoloration of the metal thin film through the transparent
substrate and identify the type of any corrosive gas present in the environment based on
correlation between the corrosive gas type and the degree of the metal thin film
discoloration known from the observation.25
[0004] For example, Japanese Patent Laying-Open No. 2006-10497 (PTL 2) describes
an environment diagnostic tool that determines the type and concentration of any
corrosive gas present in an environment where the tool is installed. The environment
diagnostic tool includes a thin film. This thin film is made of at least two kinds of
metal and serially changes in composition within the plane. This environment30
diagnostic tool determines the type and concentration of corrosive gas present in the
- 3 -
installation environment based on the direction and speed in which the resistance
neutral point between any two points with different compositions on the thin film (any
three points if the thin film is made of three kinds of metals) moves due to corrosion.
CITATION LIST
PATENT LITERATURE5
[0005] PTL 1: WO 2020/039611
PTL 2: Japanese Patent Laying-Open No. 2006-10497
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0006] The technology described in PTL 1 may require a device of complexity, like10
camera, for image processing. The technology described in PTL 2 may need a
terminal to measure the resistance neutral point. Thus, these technologies of the
known art may both demand relatively large apparatuses, which may be difficult to be
installed in any compact electric devices.
[0007] These technologies do not assume to determine whether any one of multiple15
types of corrosive gases exists alone or multiple types of corrosive gases coexist.
[0008] To address these issues of the known art, this disclosure is directed to providing
a small sensor allowed to determine whether one of the first type of corrosive gas and
the second type of corrosive gas is present or the first type of corrosive gas and the
second type of corrosive gas are coexistent, and an electric device equipped with the20
sensor.
SOLUTION TO PROBLEM
[0009] A sensor according to an aspect of this disclosure identifies the type of a
corrosive gas present in an environment. The type of the corrosive gas at least
includes a first type and a second type. The sensor comprises: a sensor body25
including at least three structures; a measurer to measure a resistance value of each of
the at least three structures or a resistance value of the sensor body; an analyzer to
identify the type of the corrosive gas present in the environment based on the resistance
value measured by the measurer and corrosion resistance information that represents a
magnitude relation in corrosion resistance between the at least three structures for each30
environment; and a notification device to notify a content identified by the analyzer.
- 4 -
The at least three structures include: a first structure comprising a thin film including a
first metallic material, the thin film being exposed in the environment; a second
structure comprising a thin film including a second metallic material that differs from
the first metallic material, the thin film being exposed in the environment; and a third
structure comprising a thin film including the second metallic material, a surface of the5
thin film exposed in the environment being covered with a coating material. The
corrosive gas of the first type and the corrosive gas of the second type each cause
corrosion of the first metallic material and the second metallic material. The
magnitude relation in corrosion resistance between the at least three structures differs
between a first environment, a second environment, and a third environment. The10
corrosive gas of the first type is present and the corrosive gas of the second type is not
present in the first environment. The corrosive gas of the second type is present and
the corrosive gas of the first type is not present in the second environment. The
corrosive gas of the first type and the corrosive gas of the second type are both present
in the third environment.15
[0010] An electric device according to another aspect of this disclosure is equipped
with the sensor described above.
ADVANTAGEOUS EFFECTS OF INVENTION
[0011] The technology disclosed herein may successfully provide a small sensor
allowed to determine whether one of the first type of corrosive gas and the second type20
of corrosive gas is present or the first type of corrosive gas and the second type of
corrosive gas are coexistent, and an electric device equipped with the sensor.
BRIEF DESCRIPTION OF DRAWINGS
[0012] Fig. 1 is a block diagram that illustrates an electric device equipped with a
sensor according to a first embodiment of this disclosure.25
Fig. 2 is a drawing that illustrates an exemplified sensor body according to the
first embodiment.
Fig. 3 is a cross-sectional view of Fig. 2 from a wiring 41, through a second
structure 121B, to a wiring 42.
Fig. 4 is a perspective view of an exemplified first structure or second structure30
according to the first embodiment.
- 5 -
Fig. 5 is a cross-sectional view along V-V line in Fig. 4.
Fig. 6 is a perspective view of an exemplified third structure according to the
first embodiment.
Fig. 7 is a cross-sectional view along VII-VII line in Fig. 6.
Fig. 8 is a perspective view of another exemplified first structure or second5
structure according to the first embodiment.
Fig. 9 is a cross-sectional view along IX-IX line in Fig. 8.
Fig. 10 is a perspective view of another exemplified third structure according to
the first embodiment.
Fig. 11 is a cross-sectional view along XI-XI line in Fig. 10.10
Fig. 12 is a table that shows an example of corrosion resistance information.
Fig. 13 is a flow chart of an exemplified analyzing process according to the first
embodiment.
Fig. 14 is a flow chart of the exemplified analyzing process according to the
first embodiment.15
Fig. 15 is a flow chart of the exemplified analyzing process according to the
first embodiment.
Fig. 16 is a table of an example of the corrosion resistance information
according to a modified example of the first embodiment.
Fig. 17 is a graph drawn to describe a corrosion speed calculation method20
according to a second embodiment of this disclosure.
Fig. 18 is a table of exemplified test conditions applied to a test performed to
formulate an estimating formula.
Fig. 19 is a block diagram that illustrates an electric device equipped with a
sensor according to a fourth embodiment of this disclosure.25
Fig. 20 is a perspective view of exemplified first and second structures
according to the fourth embodiment.
Fig. 21 is a cross-sectional view along XXI-XXI line in Fig. 20.
Fig. 22 is a perspective view of an exemplified third structure according to the
fourth embodiment.30
Fig. 23 is a cross-sectional view along XXIII-XXIII line in Fig. 22.
- 6 -
Fig. 24 is a drawing that illustrates an exemplified sensor body according to the
fourth embodiment.
Fig. 25 is a flow chart of a process to record resistance value changes.
Fig. 26 is a flow chart of an exemplified analyzing process according to the
fourth embodiment.5
Fig. 27 is a flow chart of an exemplified analyzing process according to a fifth
embodiment of this disclosure.
Fig. 28 is a drawing that illustrates an exemplified sensor body according to a
sixth embodiment of this disclosure.
Fig. 29 is a flow chart of an exemplified analyzing process according to the10
sixth embodiment.
DESCRIPTION OF EMBODIMENTS
[0013] Embodiments of the technology disclosed herein are hereinafter described
referring to the accompanying drawings. In the description below, like components
and technical or structural features are illustrated with the same reference signs. Also,15
they are referred to likewise and have similar functional features. Such components
and technical or structural features, therefore, will not be repeatedly described in detail.
The embodiments and modified examples hereinafter described may be suitably
selected and combined.
[0014] The corrosive gas described herein is a collective term used for sulfur-based20
gases, chlorine-based gases and nitrogen oxides. The sulfur-based gases are classified
into sublimed sulfur (S8) and other sulfur-based gases. The other sulfur-based gases
may include, for example, hydrogen sulfide (H2S) and sulfur dioxide (SO2). The other
sulfur-based gases are examples of the corrosive gas of the “first type”, while sublimed
sulfur is an example of the corrosive gas of the “second type”. The chlorine-based25
gases include chlorine gas (Cl2). The chlorine gas is an example of the corrosive gas
of a “third type”. The nitrogen oxides (NOx) may include nitrogen dioxide (NO2).
[0015] Silver (Ag) reacts sensitively with sublimed sulfur and chlorine gas. Copper
(Cu) reacts sensitively with hydrogen sulfide, sulfur dioxide and nitrogen dioxide.
Nickel (Ni) reacts sensitively with sulfur dioxide and chlorine gas. Aluminum (Al)30
reacts sensitively with sulfur dioxide and chlorine gas. Tin (Sn) reacts sensitively
- 7 -
with chlorine gas.
[0016] In the description given below, a “first environment” refers to an environment
where a gas included in the other sulfur-based gases is present and sublimed sulfur is
not present, a “second environment” refers to an environment where sublimed sulfur is
present and the other sulfur-based gases are not present, and a “third environment”5
refers to an environment where a gas included in the other sulfur-based gases and
sublimed sulfur are coexistent and the gas included in the other sulfur-based gases has a
higher concentration than the sublimed sulfur.
[0017] In first to fifth embodiments of this disclosure, the type of the corrosive gas
present in a target environment is limited to a sulfur-based gas, and it is determined10
whether one of sublimed sulfur and any other sulfur-based gas is present or sublimed
sulfur and any other sulfur-based gas are coexistent. In a sixth embodiment of this
disclosure, the types of corrosive gases that can be present in a target environment are
limited to a sulfur-based gas and chlorine gas, and the type of any corrosive gas present
in the environment is identified.15
[0018] First embodiment
Fig. 1 is a block diagram that illustrates an electric device equipped with a
sensor according to a first embodiment of this disclosure. With reference to Fig. 1, an
electric device 900 may be a power conversion device, for example, an inverter or
converter. This electric device, however, may be selected from other types of electric20
devices. Electric device 900 may be installed in, for example, a programmable logic
controller (PLC), elevator, power generator, automobile or railway facility. In an
environment where electric device 900 is thus installed and used, corrosion-induced
damage may occur in electric device 900 (more specifically, electric device body 90)
under the impact of corrosive gas.25
[0019] Electric device 900 includes a sensor 101 and electric device body 90. Sensor
101 identifies the type of any corrosive gas present in the environment where electric
device 900 (i.e., sensor 101) is installed. Sensor 101 includes a sensor body 11, a
temperature-humidity sensor 12, a resistance measurer 20, a recorder 30 (“storage” as
described herein), an analyzer 31, and a notification device 40.30
[0020] Structural features of sensor body 11 are described below with reference to Figs.
- 8 -
2 and 3. Fig. 2 is a drawing that illustrates an exemplified sensor body according to
the first embodiment. Fig. 3 is a cross-sectional view of Fig. 2 from a wiring 41,
through a second structure 121B, to a wiring 42. Fig. 3 shows a structural cross
section from wiring 41 to wiring 42 through second structure 121B, which is similar to
a structural cross section from wiring 41, through a first structure 121A, to wiring 42,5
and a structural cross section from wiring 41, through a third structure 121C, to wiring
42.
[0021] With reference to Figs. 2 and 3, sensor body 11 includes three structures (first
structure 121A, second structure 121B, third structure 121C), a circuit board 3, wirings
4, a solder 5, and a terminal changer 52. In the description given below, first structure10
121A, second structure 121B and third structure 121C may be collectively referred to
as three structures 121.
[0022] First structure 121A includes a metal thin film, specifically, a thin film made of
copper. This thin film is exposed in the environment. Copper is an example of the
“first metallic material” as described herein. Copper is corrodible by sublimed sulfur15
and also by the other sulfur-based gases. As described above, copper sensitively
reacts with the other sulfur-based gases.
[0023] Second structure 121B includes a metal thin film, specifically, a thin film made
of silver. This thin film is exposed in the environment. Silver is an example of the
“second metallic material” as described herein. Silver is corrodible by sublimed20
sulfur and also by the other sulfur-based gases. As described above, silver sensitively
reacts with sublimed sulfur.
[0024] Third structure 121C includes a metal thin film, specifically, a thin film made of
silver. A surface of this thin film exposed in the environment is covered with a
coating material including a silicone-based resin.25
[0025] The metal thin films of these three structures 121 are all 10 μm in thickness.
The coating material is also 10 μm in thickness. The metal thin films of these three
structures 121, however, may have different thicknesses. The metal thin films and the
coating material may have different thicknesses.
[0026] Circuit board 3 may be, for example, a printed board mountable with various30
wirings and electronic components.
- 9 -
[0027] Wirings 4 include a wiring 41, three wirings 42, and a wiring 43. Wiring 41,
three wirings 42, and wiring 43 are conductor wires routed on circuit board 3. Three
wirings 42 are routed correspondingly to three structures 121. Wiring 41, wirings 42
and wiring 43 are spaced apart from one another. The material of wirings 4 may be
selected from copper, tin, and chrome (Cr). The surfaces of wirings 4 may be coated5
with a resin having a very low gas permeability, for example, a resist.
[0028] The structures are each disposed so that wiring 41 is connectable to a
corresponding one of wirings 42 and are mounted onto wirings 41 and 42 with solder 5.
Terminal changer 52 is disposed so that one or more of three wirings 42 is connectable
to wiring 43. Wirings 41 and 43 are connected to resistance measurer 20 (see Fig. 1).10
Terminal changer 52 is configured so that the state of connection is changeable to and
from electrical connection and electrical isolation between resistance measurer 20 and
each of the structures (see Fig. 1). Thus, the resistance values of first structure 121A,
second structure 121B and third structure 121C may be measured separately.
[0029] Referring to Fig. 1 again, resistance measurer 20 measures the resistance values15
of first structure 121A, second structure 121B and third structure 121C. The
resistance values measured by resistance measurer 20 are stored in recorder 30. In the
example illustrated in Fig. 1, a predefined voltage is applied from electric device body
90 to between both ends of sensor body 11 (i.e., between wirings 41 and 43).
Resistance measurer 20 may include a voltmeter 201 and an ammeter 202. Voltmeter20
201 measures a voltage applied to between the both ends of sensor body 11. Ammeter
202 measures a current that flows through sensor body 11. Based on values presented
by voltmeter 201 and ammeter 202, resistance measurer 20 calculates the resistance
value of the structure currently electrically connected. Though not illustrated in the
drawings, a power supply independent of electric device body 90 (for example,25
compact battery) may be provided to apply a voltage to between the both ends of sensor
body 11.
[0030] Temperature-humidity sensor 12 measures the temperature and the humidity of
a current environment in which electric device 900 exists. The temperature and the
humidity measured by temperature-humidity sensor 12 are stored in recorder 30.30
[0031] Analyzer 31 may include, for example, a microprocessor. Analyzer 31
- 10 -
identifies a type of a corrosive gas present in the environment based on the resistance
values measured by resistance measurer 20 and corrosion resistance information
described later. Optionally, analyzer 31 may identify a type of a corrosive gas present
in the environment based on the resistance values measured by resistance measurer 20,
temperature and humidity measured by temperature-humidity sensor 12, and corrosion5
resistance information described later. The content obtained by analyzer 31 is stored
in recorder 30.
[0032] Notification device 40 includes a liquid crystal display or an LED (Light
Emitting Diode) indicator. Notification device 40 notifies a user of the content
obtained by analyzer 31.10
[0033] Recorder 30 stores the corrosion resistance information described later.
Recorder 30 associates and stores the resistance values measured by the resistance
measurer 20, the temperature and humidity measured by the temperature-humidity
sensor 12, and their measurement times. Recorder 30 also stores the content obtained
by analyzer 31.15
[0034] Electric device 900 may not be equipped with temperature-humidity sensor 12.
Recorder 30 and analyzer 31 may be installed in electric device body 90 instead of
sensor 101.
[0035] The three structures are hereinafter described in detail with reference to Figs. 4
to 11.20
[0036] Fig. 4 is a perspective view of an exemplified first structure or second structure
according to the first embodiment. Fig. 5 is a cross-sectional view along V-V line in
Fig. 4. With reference to Figs. 4 and 5, first structure 121A and second structure
121B each include an insulating substrate 6, an electrode pair 7, and a metal thin film 8.
[0037] Insulating substrate 6 is a cuboidal substrate having insulating properties. The25
material of insulating substrate 6 may be selected from aluminum oxide (Al2O3), glass
(SiO2), and silicon wafer (Si).
[0038] Electrode pair 7 includes a pair of electrodes; first electrode 71, and second
electrode 72. First electrode 71 is disposed so as to cover the upper surface in part
and one lateral surface (surface on the left side in the drawing) of insulating substrate 6.30
Second electrode 72 is disposed so as to cover the upper surface in part and the other
- 11 -
lateral surface (surface on the right side in the drawing) of insulating substrate 6 on the
opposite side of the lateral surface provided with first electrode 71. First electrode 71
and second electrode 72 are conductor thin films, which may be formed by tin plating.
First electrode 71 and second electrode 72 are electrically connected to metal thin film
8.5
[0039] Metal thin film 8 has a cuboidal shape. Metal thin film 8 is disposed on the
upper surface of insulating substrate 6, so that first electrode 71, metal thin film 8 and
second electrode 72 are serially connected to one another in the mentioned order. The
dimensions of metal thin film 8 are defined as follows; length of metal thin film 8 along
a current flow direction is film length “l”, length of metal thin film 8 in a direction10
perpendicular to the current flow direction is film width “w”, and thickness of metal
thin film 8 is film thickness “d1”.
[0040] According to the definitions above, film width “w” and film length “l” are set to
be substantially greater than film thickness d1. For instance, film thickness “d1” may
be in the range of 3 to 12 μm, film width “w” may be 0.8 mm, and film length “l” may15
be 1.6 mm.
[0041] By thus setting the three film dimensions; film width, film length and film
thickness, the film thickness may have a smallest dimension, so it is possible to narrow
down the direction in which corrosion progresses to the thickness direction of the metal
thin film 8. Further advantageously, such dimensions of the film width, film length20
and film thickness may successfully miniaturize sensor 101 (see Fig. 1).
[0042] Fig. 6 is a perspective view of an exemplified third structure according to the
first embodiment. Fig. 7 is a cross-sectional view along VII-VII line in Fig. 6. With
reference to Figs. 6 and 7, third structure 121C includes an insulating substrate 6, an
electrode pair 7, a metal thin film 8, and a coating material a1. Third structure 121C25
is configured similarly to second structure 121B except inclusion of coating material a1.
[0043] Coating material a1 is used to cover a surface of metal thin film 8 exposed in
the environment. Coating material a1 has a thickness d2, which may be either equal
to or different from the thickness of metal thin film 8.
[0044] Coating material a1 has a gas permeability specific to sublimed sulfur. Thus,30
coating material a1 covering metal thin film 8 reduces the corrosion speed of this thin
- 12 -
film (i.e., higher corrosion resistance) in the first environment where sublimed sulfur is
not present. Coating material a1 covering metal thin film 8, on the other hand,
increases the corrosion speed of this thin film (i.e., lower corrosion resistance) in the
second environment and the third environment where sublimed sulfur is present. As a
result, the magnitude relation in corrosion resistance between second structure 121B5
and third structure 121C differs between an environment where sublimed sulfur is not
present (first environment) and an environment where sublimed sulfur is present
(second or third environment).
[0045] Copper may react more sensitively than silver with the other sulfur-based gases.
In other words, copper may have a lower corrosion resistance than that of silver to the10
other sulfur-based gases. As described above, metal thin film 8 of first structure 121A
is made of copper, while metal thin film 8 of second structure 121B is made of silver.
Hence, the magnitude relation in corrosion resistance between first structure 121A and
second structure 121B differs between an environment where a gas included in the
other sulfur-based gases is present (first or third environment) and an environment15
where the other sulfur-based gases are not present (second environment).
[0046] Thus, the magnitude relation in corrosion resistance between first structure
121A, second structure 121B and third structure 121C differs between the first
environment, the second environment and the third environment.
[0047] The materials and thicknesses of metal thin film 8 and of the coating material a120
described so far are just a few examples. The materials and thicknesses of metal thin
film 8 and of the coating material a1 may be set otherwise insofar as the magnitude
relation in corrosion resistance between first structure 121A, second structure 121B and
third structure 121C differs between the first environment, the second environment and
the third environment.25
[0048] Specifically, the material used to form metal thin film 8 may be selected from
silver, copper, nickel, tin, aluminum and an alloy thereof. These metals have smaller
electric resistances than most of oxides and may react with most of corrosive gases.
The mentioned materials, therefore, may be suitably used to identify the type of
corrosive gas present in the environment where electric device 900 is exposed.30
[0049] Coating material a1 may desirably have a gas permeability or water vapor
- 13 -
permeability specific to corrosive gas of a certain type. Examples of the coating
material a1 may include coating materials including urethan-based resins, coating
materials including acrylic resins, coating materials including ester-based resins,
coating materials including epoxy-based resins, and agar. The gas permeability may
preferably have an oxygen permeability ranging from approximately 1000 to 400005
[cc/m2·day at 20°C (2 mm)].
[0050] Figs. 4 to 7 shows just an exemplified shape of the metal thin film. Other
possible shapes of the metal thin film are hereinafter described with reference to Figs. 8
to 11.
[0051] Fig. 8 is a perspective view of another exemplified first structure or second10
structure according to the first embodiment. Fig. 9 is a cross-sectional view along IX-
IX line in Fig. 8. Fig. 10 is a perspective view of another exemplified third structure
according to the first embodiment. Fig. 11 is a cross-sectional view along XI-XI line
in Fig. 10.
[0052] In another example, metal thin film 8 may optionally have a tortuous shape with15
multiple bends at equal intervals, with reference to Figs. 8 to 11. The structures of
this example are configured similarly to the structures illustrated in Figs. 4 to 7 except
that their metal thin films 8 each have a tortuous shape with multiple bends at equal
intervals.
[0053] In this example, a film length (physical length of metal thin film 8 from one end20
e1 to another end e2) is 1 m, film width “w” is 0.1 mm, and an interval “s” between
bends of the tortuous shape is approximately 0.1 mm. By thus setting the lengths to
these values, sensor 101 (see Fig. 1) may be miniaturized. These lengths and
particular shape may increase an area of corrosion of metal thin film 8, allowing sensor
101 to achieve an improved precision of analysis.25
[0054] While structures illustrated in Figs. 4 and 6 are hereinafter described as typical
examples of three structures, structures illustrated in Figs. 8 and 10 may instead be used.
[0055] (Corrosion resistance information)
The corrosion resistance information is hereinafter described with reference
mainly to Figs. 1, 2 and 12. Fig. 12 is a table that shows an example of corrosion30
resistance information. The corrosion resistance information represents the magnitude
- 14 -
relation in corrosion resistance between the structures included in sensor 101 for each
environment. The structures in the table of Fig. 12 are sequentially numbered as 1, 2,
3 in the order of lower to higher per-environment corrosion resistance.
[0056] The magnitude relation in corrosion resistance between the structures included
in sensor 101 for each environment may be calculated as described below. A5
calculation method is hereinafter described, in which the magnitude relation in
corrosion resistance between three structures 121 for each environment is calculated.
[0057] First, sensor 101 including first structure 121A, second structure 121B and third
structure 121C or electric device 900 mounted with this sensor 101 is exposed for a
certain period of time in the first environment, the second environment and the third10
environment. The initial film thickness in each structure should preferably be large
enough (for example, 20 μm). The certain period of time may be, for example, one
month. After the certain period of time has passed, for each environment of exposure,
a remaining film thickness of metal thin film 8 in each of first structure 121A, second
structure 121B and third structure 121C is measured.15
[0058] The remaining film thickness refers to the thickness of a portion still in metallic
state of metal thin film 8 unaffected by any corrosive gas. To measure the thickness
of metal thin film 8, its remaining film thickness may be actually measured through
cross-sectional observation, or the thickness of a film portion in metallic state may be
calculated from a volume-electric resistance correlation formula (formula 1 described20
later) of this metal thin film 8.
[0059] Next, an amount of reduction of metal thin film 8 in each structure is calculated
based on the measured remaining film thickness.
[0060] An example is given here, in which the remaining film thickness in first
structure 121A exposed in the first environment is 10 μm, the remaining film thickness25
in second structure 121B exposed in the first environment is 15 μm, and the remaining
film thickness in third structure 121C exposed in the first environment is 18 μm. In
this example, metal thin films 8 in the structures are reduced by 20 μm - 10 μm = 10
μm in first structure 121A, by 20 μm - 15μm = 5 μm in second structure 121B, and by
20 μm - 18 μm =2 μm in third structure 121C.30
[0061] The corrosion resistance may be lower with a greater amount of reduction from
- 15 -
the initial film thickness. Therefore, the magnitude relation in corrosion resistance
between first, second and third structures 121A, 121B and 121C may be decided so that
the structure with a greater amount of reduction from the initial film thickness has a
lower corrosion resistance. In the above example, the magnitude relation in corrosion
resistance between these three structures in the first environment may be decided as5
follows; first structure 121A < second structure 121B < third structure 121C. The
magnitude relation in corrosion resistance between these three structures 121 may be
decided likewise for the second environment and third environment based on the
amounts of reduction from the initial film thickness.
[0062] The magnitude relation in corrosion resistance between two or more structures10
may be decided based on the corrosion speed or corrosion ratio. In this instance, the
magnitude relation in corrosion resistance between the structures may be decided so
that the structure with a higher corrosion speed or a greater corrosion ratio has a lower
corrosion resistance.
[0063] The magnitude relation in corrosion resistance between two or more structures15
may be decided based on wire breakage situation. In this instance, the magnitude
relation in corrosion resistance between the structures may be decided so that any
structure undergoing wire breakage in an earlier stage than the other structures has a
lower corrosion resistance.
[0064] In this embodiment, information on the magnitude relation in corrosion20
resistance between three structures 121 for each environment thus decided (i.e.,
corrosion resistance information) is stored in recorder 30. In this embodiment,
analyzer 31 calculates the corrosion speed of each of three structures 121 in an
environment where sensor 101 (or electric device 900) is really exposed and then
determines the magnitude relation in corrosion resistance between three structures 12125
based on the calculated corrosion speeds. Then, analyzer 31 identifies the type of
corrosive gas based on the determined magnitude relation in corrosion resistance
between three structures 121 and the magnitude relation in corrosion resistance
between three structures 121 for each environment indicated by the corrosion resistance
information.30
[0065] Fig. 12 shows an example of the magnitude relation in corrosion resistance
- 16 -
between three structures 121 for each environment. In case the material and thickness
of metal thin film 8 and the material and thickness of coating material a1 have values
that differ from those illustrated in Fig. 2, the magnitude relation in corrosion resistance
between three structures 121 for each environment may naturally differ from what is
illustrated in Fig. 12. Under such circumstances, the magnitude relation in corrosion5
resistance between three structures 121 for each environment may be decided as
described above and then stored in recorder 30 as the corrosion resistance information.
[0066] (Processing details of sensor 101)
An analyzing process by sensor 101 is described below with reference to Figs. 1
and 13 to 15. Figs. 13 to 15 are flow charts of an exemplified analyzing process10
according to the first embodiment. The steps illustrated in Figs. 13 to 15 are
periodically invoked at predefined regular intervals from a main routine not illustrated
in the drawings and then carried out by analyzer 31. The steps (hereinafter, simply
“S”) are basically actualized through software processing by analyzer 31, however,
may be actualized through hardware processing using, for example, an electronic15
circuit embedded in analyzer 31.
[0067] With reference to Fig. 13, S1 to S12 are steps of measuring a resistance value.
Analyzer 31 measures resistance values at certain time intervals using a timing device,
for example, a microcontroller embedded in electric device 900.
[0068] S1 to S4 are steps of measuring the resistance value of first structure 121A. In20
S1, analyzer 31 activates terminal changer 52 for switchover of terminals. In S2,
analyzer 31 electrically connects first structure 121A and resistance measurer 20 to
each other. In S3, analyzer 31 measures, using resistance measurer 20, the resistance
value of first structure 121A between its both ends. In S4, analyzer 31 writes, in
recorder 30, the resistance value measured by resistance measurer 20, time when the25
resistance value was measured (measurement time), and temperature and humidity
measured by temperature-humidity sensor 12 at the time of measuring the resistance
value, as the result of measurement obtained from first structure 121A. Analyzer 31
may write, in recorder 30, the resistance value measured by resistance measurer 20 and
time when the resistance value was measured (measurement time) alone, as the result30
of measurement obtained from first structure 121A.
- 17 -
[0069] S5 to S8 are steps of measuring the resistance value of second structure 121B.
In S5, analyzer 31 activates terminal changer 52 for switchover of terminals. In S6,
analyzer 31 electrically connects second structure 121B and resistance measurer 20 to
each other. In S7, analyzer 31 measures, using resistance measurer 20, the resistance
value of second structure 121B between its both ends. In S8, analyzer 31 writes, in5
recorder 30, the resistance value measured by resistance measurer 20, time when the
resistance value was measured (measurement time), and temperature and humidity
measured by temperature-humidity sensor 12 at the time of measuring the resistance
value, as the result of measurement obtained from second structure 121B. Analyzer
31 may write, in recorder 30, the resistance value measured by resistance measurer 2010
and time when the resistance value was measured (measurement time) alone, as the
result of measurement obtained from second structure 121B.
[0070] S9 to S12 are steps of measuring the resistance value of third structure 121C.
In S9, analyzer 31 activates terminal changer 52 for switchover of terminals. In S10,
analyzer 31 electrically connects third structure 121C and resistance measurer 20 to15
each other. In S11, analyzer 31 measures, using resistance measurer 20, the resistance
value of third structure 121C between its both ends. In S12, analyzer 31 writes, in
recorder 30, the resistance value measured by resistance measurer 20, time when the
resistance value was measured (measurement time), and temperature and humidity
measured by temperature-humidity sensor 12 at the time of measuring the resistance20
value, as the result of measurement obtained from third structure 121C. Analyzer 31
may write, in recorder 30, the resistance value measured by resistance measurer 20 and
time when the resistance value was measured (measurement time) alone, as the result
of measurement obtained from third structure 121C.
[0071] The results of measurement thus obtained are used to calculate the corrosion25
speeds of first structure 121A, second structure 121B, and third structure 121C. When
S12 is over, analyzer 31 proceeds to S13 illustrated in Fig. 14.
[0072] With reference to Fig. 14, S13 to S16 are steps of calculating the corrosion
speed of first structure 121A. In S13, analyzer 31 refers to the result of measurement
obtained from first structure 121A stored in recorder 30 to determine whether wire30
breakage has occurred or not in first structure 121A. The state in which wire breakage
- 18 -
has occurred in one structure refers to a state in which metal thin film 8 included in the
one structure has been considerably corroded and mostly replaced with a corrosion
product, resulting in a soaring resistance. Then, analyzer 31 may determine that wire
breakage has occurred in the one structure when its resistance value is found to be, for
example, 100 times greater than an initial value.5
[0073] When wire breakage has occurred in first structure 121A (YES in S13),
analyzer 31 proceeds to S17. When wire breakage has not occurred in first structure
121A (NO in S13), analyzer 31 proceeds to S14.
[0074] In S14, analyzer 31 calculates a remaining film thickness dl1121A of metal thin
film 8 in first structure 121A using the following formula 1 based on a latest resistance10
value Rl1121A of first structure 121A stored in recorder 30.
[0075] dl1121A = ρ × l / (w × Rl1121A) [m] ... (Formula 1)
(where dl1121A: latest film thickness (remaining film thickness) of metal thin
film 8 in first structure 121A, ρ: electrical resistivity of a metallic material included in
metal thin film 8, l: film length (design value) of metal thin film 8, w: film width15
(design value) of metal thin film 8, Rl1121A: latest resistance value of metal thin film 8
in first structure 121A).
[0076] Analyzer 31 may use the following formula 2 to correct “ρ” with Templ1(°C);
temperature when the resistance value stored in recorder 30 was measured.
[0077] ρ = ρ20 × (1 + k × 10-3 × (Templ1 - 20)) [10-8Ω·m] ... (Formula 2)20
(where ρ20: electric resistivity of metal [10-8Ω·m] at 20°C, k: temperature
coefficient of electric resistivity [10-11Ω·m/K]).
[0078] It should be noted that “ρ20” and “k” have specific values for each of different
types of metallic materials included in metal thin film 8, which are applied and used.
[0079] In S15, analyzer 31 calculates a corrosion speed V121A of first structure 121A25
using the following formula 3.
[0080] V121A = (dl0121A - dl1121A) / (Tl1-T0) [m/h] ... (Formula 3)
(where dl0121A: initial film thickness of metal thin film 8 in first structure 121A,
Tl1: measurement time of latest resistance value Rl1121A, T0: initial measurement time).
[0081] The initial film thickness of metal thin film 8 in each structure is prestored in30
recorder 30. In S16, analyzer 31 writes, in recorder 30, corrosion speed V121A as the
- 19 -
latest corrosion speed of first structure 121A.
[0082] S17 to S20 are steps of calculating a corrosion speed V121B of second structure
121B. In S17, analyzer 31 refers to the result of measurement obtained from second
structure 121B stored in recorder 30 to determine whether wire breakage has occurred
or not in second structure 121B. When wire breakage has occurred in second5
structure 121B (YES in S17), analyzer 31 proceeds to S21. When wire breakage has
not occurred in second structure 121B (NO in S17), analyzer 31 proceeds to S18.
[0083] In S18 to S20, analyzer 31 calculates corrosion speed V121B of second structure
121B similarly to S14 to S16 and then writes the calculated corrosion speed V121B in
recorder 30 as the latest corrosion speed of second structure 121B.10
[0084] S21 to S24 are steps of calculating a corrosion speed V121C of third structure
121C. In S21, analyzer 31 refers to the result of measurement obtained from third
structure 121C stored in recorder 30 to determine whether wire breakage has occurred
or not in third structure 121C. When wire breakage has occurred in third structure
121C (YES in S21), analyzer 31 proceeds to S25. When wire breakage has not15
occurred in third structure 121C (NO in S21), analyzer 31 proceeds to S22.
[0085] In S22 to S24, analyzer 31 calculates the corrosion speed V121C of third
structure 121C similarly to S14 to S16 and then writes the calculated the corrosion
speed V121C in recorder 30 as the latest corrosion speed of third structure 121C. When
S21 or S24 is over, analyzer 31 proceeds to S25 illustrated in Fig. 15.20
[0086] With reference to Fig. 15, S25 to S36 are steps of identifying the type of
corrosive gas present in the environment and notifying the identified content. In S25,
analyzer 31 extracts the latest corrosion speeds V121A, V121B, and V121C from recorder
30. When it is determined that wire breakage has occurred in S13, S17 and/or S21,
analyzer 31 extracts, from recorder 30, the latest one of corrosion speeds calculated25
before the wire breakage occurs.
[0087] In S26, analyzer 31 determines whether corrosion speeds V121A, V121B, and
V121C are all zero. When corrosion speeds V121A, V121B, and V121C are all zero (YES in
S26), analyzer 31 proceeds to S27. When at least one of corrosion speeds V121A, V121B,
and V121C is not zero (NO in S26), analyzer 31 proceeds to S28.30
[0088] In S27, analyzer 31 determines that no sulfur-based gas is present.
- 20 -
[0089] In S28, analyzer 31 determines the magnitude relation in corrosion resistance
between three structures 121 based on the corrosion speeds V121A, V121B and V121C.
Higher corrosion speed may indicate lower corrosion resistance. Analyzer 31,
therefore, determines the magnitude relation in corrosion resistance between three
structures 121 so that the corrosion resistance is lower with a higher corrosion speed.5
[0090] In S29, analyzer 31 refers to the corrosion resistance information stored in
recorder 30 to determine whether the determined magnitude relation in corrosion
resistance between three structures 121 is consistent with the magnitude relation in
corrosion resistance in the first environment. When the determined magnitude
relation in corrosion resistance between three structures 121 is consistent with the10
magnitude relation in corrosion resistance in the first environment (YES in S29),
analyzer 31 proceeds to S30. When the determined magnitude relation in corrosion
resistance between three structures 121 is not consistent with the magnitude relation in
corrosion resistance in the first environment (NO in S29), analyzer 31 proceeds to S31.
[0091] In S30, analyzer 31 identifies the type of corrosive gas present in the15
environment as a gas included in the other sulfur-based gases.
[0092] In S31, analyzer 31 refers to the corrosion resistance information stored in
recorder 30 to determine whether the determined magnitude relation in corrosion
resistance between three structures 121 is consistent with the magnitude relation in
corrosion resistance in the second environment. When the determined magnitude20
relation in corrosion resistance between three structures 121 is consistent with the
magnitude relation in corrosion resistance in the second environment (YES in S31),
analyzer 31 proceeds to S32. When the determined magnitude relation in corrosion
resistance between three structures 121 is not consistent with the magnitude relation in
corrosion resistance in the second environment (NO in S31), analyzer 31 proceeds to25
S33.
[0093] In S32, analyzer 31 identifies the type of corrosive gas present in the
environment as sublimed sulfur.
[0094] In S33, analyzer 31 refers to the corrosion resistance information stored in
recorder 30 to determine whether the determined magnitude relation in corrosion30
resistance between three structures 121 is consistent with the magnitude relation in
- 21 -
corrosion resistance in the third environment. When the determined magnitude
relation in corrosion resistance between three structures 121 is consistent with the
magnitude relation in corrosion resistance in the third environment (YES in S33),
analyzer 31 proceeds to S34. When the determined magnitude relation in corrosion
resistance between three structures 121 is not consistent with the magnitude relation in5
corrosion resistance in the third environment (NO in S33), analyzer 31 proceeds to S35.
[0095] In S34, analyzer 31 identifies the types of corrosive gases present in the
environment as sublimed sulfur and a gas included in the other sulfur-based gases.
[0096] In S35, analyzer 31 determines that the major cause of corrosion is none of the
sulfur-based gases.10
[0097] In S36, analyzer 31 prompts notification device 40 to notify the obtained
content. For example, analyzer 31 displays the content obtained in S27, S30, S32,
S34 or S35 on a liquid crystal display.
[0098] Following on from S27, analyzer 31 may display, on the liquid crystal display,
such a message as “No sulfur-based gas”, “No impact from sulfur-based gas” or15
“Ready for continued use”. Following on from S27, analyzer 31 may not display any
message on the liquid crystal display.
[0099] Following on from S30, S32 or S34, analyzer 31 may display, on the liquid
crystal display, such a message as “The corrosive gas is ***”.
[0100] Following on from S35, analyzer 31 may display, on the liquid crystal display,20
such a message as “Discuss any other cause of corrosion but sulfur-based gases”.
[0101] When S36 is over, analyzer 31 ends the processing steps of Figs. 13 to 15.
[0102] When LED indicators are used as notification device 40, analyzer 31, in S36,
prompts a corresponding one of the indicators to emit light to let a user know the
obtained content. To be specific, analyzer 31 previously decides a portion to be25
illuminated or a color to be presented in each one of the indicators for different results
on the environmental corrosive gas; “when sulfur-based gas is not present”, “when the
type of corrosive gas present in the environment is sublimed sulfur”, “when the type of
corrosive gas present in the environment is other sulfur-based gas”, “when the types of
corrosive gases present in the environment are sublimed sulfur and other sulfur-based30
- 22 -
gas”, and “when corrosion factors other than sulfur-based gases can be considered”.
Then, analyzer 31 prompts an appropriate one of the indicators to emit light.
[0103] When a buzzer or a speaker is used as notification device 40, analyzer 31, in
S36, may notify the identified content using sound.
[0104] Analyzer 31 may determine whether wire breakage has occurred or not based5
on the film thickness of a metallic portion of metal thin film 8 included in the structure
(i.e., remaining film thickness). For example, analyzer 31 may determine that wire
breakage has occurred in the structure when the remaining film thickness of metal thin
film 8 is found to be less than 1% of the initial film thickness. In this instance, S13,
S17 and S21 are carried out subsequent to S14, S18 and S22 respectively.10
[0105] In S28, analyzer 31 may determine the magnitude relation in corrosion
resistance between three structures 121 based on the corrosion ratios of three structures
121. In this instance, analyzer 31, in S15, S19 and S23, calculates the corrosion ratios
instead of the corrosion speeds. In S16, S20 and S24, analyzer 31 writes, in recorder
30, the corrosion ratios instead of the corrosion speeds. In S25, analyzer 31 extracts15
the latest corrosion ratios from recorder 30. In S28, analyzer 31 determines the
magnitude relation in corrosion resistance between three structures 121 so that the
corrosion resistance is lower with a higher corrosion ratio.
[0106] Below is given the formula 4 used to calculate a corrosion ratio P121A of first
structure 121A.20
[0107] P121A = (dl0121A - dl1121A) / dl0121A [No unit] ... (Formula 4)
[0108] A corrosion ratio P121B of second structure 121B and a corrosion ratio P121C of
third structure 121C may be calculated likewise.
[0109] When the corrosion ratios are calculated instead of the corrosion speeds in S15,
S19 and S23, analyzer 31 determines in S26 whether corrosion ratios P121A, P121B, and25
P121C are all zero. When corrosion ratios P121A, P121B, and P121C are all zero (YES in
S26), analyzer 31 proceeds to S27. When at least one of corrosion ratios P121A, P121B,
and P121C is not zero (NO in S26), analyzer 31 proceeds to S28.
[0110] Next, verification results on usefulness of sensor 101 according to the first
embodiment are hereinafter described. In working examples described below, electric30
- 23 -
device 900 equipped with sensor 101 (inverter in these examples) was exposed in a
corrosive gas-present environment. Sensor 101 includes three structures 121
described above (first structure 121A, second structure 121B, and third structure 121C).
The material of metal thin film 8 in first structure 121A was copper. The material of
metal thin film 8 in second and third structures 121B and 121C was silver. The metal5
thin films 8 of these three structures 121 were all 10 μm in thickness. Coating
material a1 of third structure 121C was a silicone-based resin having the oxygen
permeability of 31000[cc/m2·day at 20°C (2 mm)] and having the thickness of 10 μm.
[0111] First embodiment, first working example
Electric device 900 was exposed in an environment under the condition of10
40°C/95% RH/3 ppm H2S. On day 3 after the exposure started, the magnitude
relation in corrosion speed between three structures 121 was defined as follows; first
structure 121A > second structure 121B > third structure 121C. Under the condition
in which H2S was substituted with SO2, the magnitude relation in corrosion speed in
three structures 121 was defined as follows; first structure 121A > second structure15
121B > third structure 121C.
[0112] This verification result demonstrates that, in an environment where H2S or SO2
is present and S8 is not present (i.e., first environment), the magnitude relation in
corrosion resistance between three structures may be defined as follows; first structure
121A < second structure 121B < third structure 121C.20
[0113] First embodiment, second working example
Electric device 900 was exposed in an environment at 75°C where S8 was
present. On day 4 after the exposure started, wire breakage occurred in third structure
121C. On day 7 after the exposure started, wire breakage occurred in second structure
121B. On day 20 after the exposure started, wire breakage occurred in first structure25
121A.
[0114] The corrosion resistance may be lower with an earlier occurrence of wire
breakage. This verification result demonstrates that, in an environment where S8 is
present and neither H2S nor SO2 is present (i.e., second environment), the magnitude
relation in corrosion resistance between three structures may be defined as follows; first30
structure 121A > second structure 121B > third structure 121C.
- 24 -
[0115] First embodiment, third working example
Electric device 900 was exposed in an environment under the condition of
40°C/95% RH/ (0.2 ppm S8+3 ppm H2S). On day 5 after the exposure started, wire
breakage occurred in first structure 121A. On day 8 after the exposure started, wire
breakage occurred in third structure 121C.5
[0116] This verification result demonstrates that, in an environment where S8 and H2S
coexist and the concentration of H2S is higher than that of S8 (i.e., third environment),
the magnitude relation in corrosion resistance between three structures may be defined
as follows; first structure 121A < third structure 121C < second structure 121B.
[0117] The verification results obtained from the first, second and third working10
examples of the first embodiment demonstrate that electric device 900 may be
determined as being in the first environment, i.e., the type of corrosive gas present in
the environment may be determined as a gas included in the other sulfur-based gases
when the magnitude relation in corrosion resistance between three structures is defined
as follows; first structure 121A < second structure 121B < third structure 121C.15
[0118] These verification results also demonstrate that electric device 900 may be
determined as being in the second environment, i.e., the type of corrosive gas present in
the environment may be determined as sublimed sulfur when the magnitude relation in
corrosion resistance between three structures is defined as follows; first structure 121A
> second structure 121B > third structure 121C.20
[0119] These verification results further demonstrate that electric device 900 may be
determined as being in the third environment, i.e., in the environment may be
determined as coexistence of sublimed sulfur and a gas included in the other sulfur-
based gases when the magnitude relation in corrosion resistance between three
structures is defined as follows; first structure 121A < third structure 121C < second25
structure 121B.
[0120] According to the first embodiment, sensor 101 includes three structures 121,
and the magnitude relation in corrosion resistance between three structures 121 differs
between first environment, second environment, and third environment. According to
the first embodiment, resistance values of the structures are measured and used to30
specify the corrosion speeds or corrosion ratios of these structures. The magnitude
- 25 -
relation in corrosion resistance between three structures 121 may be thus successfully
determined. Further, the type of corrosive gas present in the environment may be
identifiable by comparing the determined magnitude relation in corrosion resistance
between three structures 121 with the corrosion resistance information stored in
recorder 30. Then, it can be determined whether one of the first type of corrosive gas5
and the second type of corrosive gas is present or the first type of corrosive gas and the
second type of corrosive gas are coexistent.
[0121] According to the first embodiment, the corrosion speed is calculated based on
the latest remaining film thickness and initial film thickness of metal thin film 8. This
means that the corrosion speed is calculated based on the total amount of corrosion10
accumulated since the manufacture of electric device 900. Thus, the type of any
corrosive gas that most heavily affected electric device 900 so far after the manufacture
of electric device 900 may be identified.
[0122] Sensor 101 may preferably include three or more structures. Fig. 16 presents
an exemplified magnitude relation in corrosion resistance between four structures of15
sensor 101 for each environment.
[0123] Fig. 16 is a table of an example of corrosion resistance information according to
a modified example of the first embodiment. Sensor 101 includes four structures; first
structure 121A, second structure 121B, third structure 121C, and a fourth structure.
The fourth structure is similar to third structure 121C except that the coating material is20
replaced with a urethane-based resin.
[0124] As illustrated in Fig. 16, the magnitude relation in corrosion resistance between
these four structures differs between a first environment, a second environment, and a
third environment. Thus, based on the magnitude relation in corrosion resistance
between four structures exposed in a certain environment, the type of any corrosive gas25
present in this environment may be identified. Then, it can be determined whether
one of the first type of corrosive gas and the second type of corrosive gas is present or
the first type of corrosive gas and the second type of corrosive gas are coexistent.
[0125] Second Embodiment
An electric device according to a second embodiment of this disclosure is30
configured similarly to electric device 900 according to the first embodiment. An
- 26 -
analyzing process according to the second embodiment is configured similarly to the
analyzing process according to the first embodiment except that the corrosion speed is
calculated differently. In the first embodiment, analyzer 31 calculates the corrosion
speed based on the latest remaining film thickness and initial film thickness of metal
thin film 8. In the second embodiment, analyzer 31 calculates the corrosion speed5
based on the latest remaining film thickness of metal thin film 8 and the remaining film
thickness of metal thin film 8 at a time point that precedes the latest measurement time
by an optional length of time.
[0126] A corrosion speed calculation method according to the second embodiment is
hereinafter described with reference mainly to Figs. 1, 14 and 17. Fig. 17 is a graph10
drawn to describe a corrosion speed calculation method according to the second
embodiment.
[0127] In the second embodiment, analyzer 31 calculates, in S14, a remaining film
thickness dl1121A of metal thin film 8 at a measurement time T1 when the latest
resistance value was measured and a remaining film thickness dl2121A of metal thin film15
8 at a measurement time T2 that precedes measurement time T1 by an optional length
of time. The optional length of time may be, for example, 24 hours. The optional
length of time may be set by analyzer 31 based on a user’s operation. Analyzer 31
calculates remaining film thickness dl2121A of metal thin film 8, using the formula 1
described above, based on a resistance value Rl2121A at measurement time T2 stored in20
recorder 30. Remaining film thickness dl1121A may be calculated as described above.
[0128] In S15, analyzer 31 calculates, using the formula 3 described above, corrosion
speed V121A of first structure 121A. At the time, analyzer 31 substitutes “dl0121A” in
the formula 3 with “dl2121A”, “Tl1” in the formula 3 with “T1”, and “T0” in the formula
3 with “T2”.25
[0129] As with the first embodiment, analyzer 31 may calculate, using the formula 4,
the corrosion ratios instead of the corrosion speeds. At the time, analyzer 31
substitutes “dl0121A” in the formula 4 with “dl2121A”.
[0130] In S18, S19 and also in S22 and S23, analyzer 31 calculates the corrosion speed
of second structure 121B and third structure 121C based on the latest remaining film30
thickness of metal thin film 8 and the remaining film thickness of metal thin film 8 at a
- 27 -
point in time earlier by an optional length of time than the latest measurement time.
[0131] Thus, the magnitude relation in corrosion resistance between three structures
121 may be successfully determined based on the latest corrosion speeds. The type of
any corrosive gas identifiable based on the magnitude relation, therefore, may be the
type of corrosive gas present in a most recent environment. As illustrated in Fig. 17,5
an environment where electric device 900 is currently located may possibly be subject
to change. In the example of Fig. 17, the environment where electric device 900 is
installed changed from the condition of “40°C/95% RH/3 ppm H2S” to the condition of
“75°C/S8”. According to the second embodiment, however, the type of corrosive gas
present in most recent environment may be identified.10
[0132] Next, verification results on usefulness of sensor 101 according to the second
embodiment are hereinafter described. In working examples described below, electric
device 900 configured similarly to the working examples of the first embodiment was
exposed in a corrosive gas-present environment.
[0133] Second embodiment, first working example15
Electric device 900 was exposed in an environment under the condition of
40°C/95% RH/ (3 ppm H2S). On day 1 after the exposure started, the magnitude
relation in corrosion speed between three structures 121 was defined as follows; first
structure 121A > second structure 121B > third structure 121C. Thus, the magnitude
relation in corrosion resistance between three structures 121 may be defined as follows;20
first structure 121A < second structure 121B < third structure 121C.
[0134] Then, this electric device 900 was removed from the environment described
above and exposed in an environment at 75°C where S8 was present. The magnitude
relation in corrosion speed between three structures 121 after two hours passed
subsequent to the environmental change until 50 hours passed subsequent to the25
environmental change was defined as follows; first structure 121A < second structure
121B < third structure 121C. Thus, the magnitude relation in corrosion resistance
between three structures 121 may be defined as follows; first structure 121A > second
structure 121B > third structure 121C.
[0135] This demonstrates that the magnitude relation in corrosion resistance between30
three structures 121 may change with an environmental change of electric device 900.
- 28 -
This may also prove that the type of any corrosive gas present in a most recent
environment is identifiable by grasping the magnitude relation in corrosion resistance
between three structures 121 in this environment.
[0136] According to the second embodiment, the corrosion speeds within an optional
range of time lengths may be successfully calculated. Thus, the magnitude relation in5
corrosion resistance between three structures 121 in a most recent environment may be
grasped and confirmed. In a most recent environment, therefore, it can be determined
whether one of the first type of corrosive gas and the second type of corrosive gas is
present or the first type of corrosive gas and the second type of corrosive gas are
coexistent.10
[0137] Third Embodiment
An electric device according to a third embodiment of this disclosure is
configured similarly to electric device 900 according to the first embodiment. In the
third embodiment, analyzer 31 identifies the type of any corrosive gas present in an
environment and also calculates the concentration of the identified corrosive gas.15
[0138] Analyzer 31 identifies the type of any corrosive gas present in an environment
in the manner described in the first or second embodiment. When the identified type
of the corrosive gas is sublimed sulfur or a gas included in the other sulfur-based gases,
analyzer 31 substitutes the measured value of a corrosion factor in the following
estimating formula to calculate the concentration of the identified corrosive gas in the20
environment. The corrosion factor is a possible cause of corrosion, examples of
which may include the temperature, humidity, and corrosive gas concentration.
[0139] Fig. 18 is a table of exemplified test conditions applied to a test performed to
formulate an estimating formula. In this test, metal thin films similar to metal thin
films 8 of sensor 101 (for example, thin films made of silver) are exposed in a plurality25
of model environments under different conditions. In the model environments,
conditions associated with corrosion factors are differently set for the environments.
In the model environments, for example, at least one of the following corrosion factors
is different per environment; environmental temperature, environmental humidity, and
corrosive gas concentration.30
[0140] In these model environments, the following conditions, for example, may be
- 29 -
defined and set; presence of H2S, temperature range of 25 to 45°C, humidity range of
60 to 90% RH, and H2S concentration range of 0.05 to 1.05 ppm. Based on the design
of experiments, these defined ranges are then divided into three levels to set a plurality
of test conditions. For instance, the conditions are; temperature levels of 25°C, 35°C
and 45°C, humidity levels of 60% RH, 75% RH and 90% RH, and corrosive gas5
concentrations of 0.05 ppm, 0.55 ppm and 1.05 ppm. Then, these conditions are
variously combined to set 27 test conditions illustrated in Fig. 18.
[0141] As illustrated in Fig. 18, these test conditions include temperature-related
condition, humidity-related condition, and corrosive gas concentration-related
condition. An equal number of metal thin films to the number of test conditions (2710
films in this example) are prepared and exposed in 27 environments specified under the
different test conditions for a certain period of time. Then, corrosion speeds (Vc1 -
Vc27) of the metal thin films are calculated from changes over time of the amounts of
corrosion of these metal thin films. Next, an estimating formula is formulated using
the technique of analysis of variance based on the calculated corrosion speeds (Vc1 -15
Vc27). The following formula 5 is an example of the estimating formula thus
formulated. The formula 5 is an estimating formula used to estimate the concentration
of H2S.
[0142] VH2S-Ag = 36.0 - 1.5T + 0.021T2 - 0.12[H2O] - 489.2[H2S] + 396.6[H2S]2 +
28.2T[H2S] - 0.39T2[H2S] - 25.1T[H2S]2 + 0.36T2[H2S]2 + 0.65[H2O] [H2S] ... (Formula20
5)
(where VH2S-Ag × 10-4: corrosion speed of silver (g/(m2·h)), T: temperature (°C),
[H2O]: humidity (% RH), and [H2S]: H2S concentration (ppm)).
[0143] When the type of any corrosive gas present in the environment is identified as a
gas included in the other sulfur-based gases, analyzer 31 substitutes the corrosion speed25
of second structure 121B, environmental temperature, and environmental humidity
respectively in “VH2S-Ag”, “T”, and “H2O” in the formula 5 to calculate the
concentration of a gas included in the other sulfur-based gases (“H2S” in this example).
The corrosion speed of second structure 121B substituted in the estimating formula is a
value calculated by analyzer 31 to identify the type of corrosive gas present in the30
environment, and the environmental temperature and humidity substituted in the
- 30 -
estimating formula are values measured by temperature-humidity sensor 12.
[0144] The estimating formula used to estimate the concentration of sublimed sulfur
may be formulated by conducting a similar experiment using a model environment
where sublimed sulfur is present. When the corrosive gas present in the environment
is identified as sublimed sulfur, analyzer 31 calculates the concentration of sublimed5
sulfur by substituting the corrosion speed of second structure 121B, environmental
temperature, and environmental humidity in the relevant formula.
[0145] Analyzer 31 prompts notification device 40 to notify the calculated
concentration.
[0146] According to the third embodiment, the concentration of any corrosive gas10
present in an environment may be successfully calculated. In the test described above,
the silver-made thin films are used as metal thin films similar to metal thin films 8
included in sensor 101, which may be replaced with thin films made of copper. In this
instance, analyzer 31 substitutes the corrosion speed of first structure 121A in the
estimating formula in place of the corrosion speed of second structure 121B.15
[0147] The estimating formula described above was formulated in a model
environment where only one type of corrosive gas is present. In the case of only one
type of corrosive gas, the corrosive gas concentration calculated using the estimating
formula may have a relatively high accuracy. However, a plurality of different
corrosive gases may be likely to coexist in real environments. Thus, the corrosive gas20
concentration calculated using the estimating formula should be considered a reference
value.
[0148] The estimating formula described above was formulated in a model
environment where the temperature, humidity and corrosive gas concentration remain
constant. In real environments, however, the temperature, humidity and corrosive gas25
concentration may often change with seasons, time slots, and/or working processes
employed. When the value of a corrosion factor most recently measured is substituted
in the estimating formula formulated based on the model environment, a true value of
the corrosive gas concentration may be difficult to obtain. To address this issue,
analyzer 31 may substitute, as the corrosion factor, an average value of the temperature30
degree and/or humidity in the estimating formula. This may allow analyzer 31 to
- 31 -
calculate the corrosive gas concentration with a higher accuracy.
[0149] As in the second embodiment, analyzer 31 may substitute the corrosion speed,
temperature and humidity measured in a relatively short period of time in the
estimating formula. This may allow analyzer 31 to calculate the corrosive gas
concentration with a higher accuracy.5
[0150] Analyzer 31 may calculate the corrosive gas concentration using a well-known
formula in place of the estimating formula described above.
[0151] Fourth Embodiment
In a fourth embodiment of this disclosure, analyzer 31 specifies wire breakage
situation, specifically, the chronological order of wire breakage that occurred by then10
from changing resistance value of the sensor body and then identifies the type of
corrosive gas present in the environment based on the specified chronological order.
[0152] Fig. 19 is a block diagram that illustrates an electric device equipped with a
sensor according to the fourth embodiment. This electric device 900A is configured
similarly to electric device 900 of the first embodiment (see Fig. 1) except the15
following differences; its sensor body is differently configured, and temperature-
humidity sensor 12 (see Fig. 1) is not installed. Electric device 900A includes a
sensor 101A and electric device body 90. Sensor 101A includes a sensor body 11A,
resistance measurer 20, recorder 30, analyzer 31, and notification device 40.
[0153] Sensor body 11A includes three structures (first structure 122A, second20
structure 122B, third structure 122C), a resistor 91, and wirings 4. In the description
given below, first structure 122A, second structure 122B and third structure 122C may
be collectively referred to as three structures 122. Wirings 4 include a wiring 41 and a
wiring 42. Wirings 4 are routed on a circuit board. Three structures 122 and resistor
91 are mounted onto wirings 41 and 42 by soldering so that wirings 41 and 42 are25
connectable to each other. Three structures 122 and resistor 91 are serially connected
to between wirings 41 and 42.
[0154] Fig. 20 is a perspective view of exemplified first and second structures
according to the fourth embodiment. Fig. 21 is a cross-sectional view along XXI-XXI
line in Fig. 20. With reference to Figs. 20 and 21, first structure 122A and second30
structure 122B are configured similarly to first structure 121A and second structure
- 32 -
121B described above except that first structure 122A and second structure 122B each
include resistor 9. First structure 122A and second structure 122B each include
insulating substrate 6, electrode pair 7, metal thin film 8, and resistor 9.
[0155] Metal thin film 8 and resistor 9 are connected in parallel to between first
electrode 71 and second electrode 72. Metal thin film 8 is disposed at a position on5
the outer side than resistor 9 and is exposed in an environment. The resistance value
of metal thin film 8 is set to a significantly smaller value than that of resistor 9.
[0156] Resistor 9 is very resistant to corrosive gases and is hardly corrodible by
corrosive gases. The material of resistor 9 may be selected from oxide
semiconductors (for example, ruthenium oxide (RuO2)). The resistance value of10
resistor 9 may preferably be higher than the resistance value of metal thin film 8.
[0157] Fig. 22 is a perspective view of an exemplified third structure according to the
fourth embodiment. Fig. 23 is a cross-sectional view along XXIII-XXIII line in Fig.
22. With reference to Figs. 22 and 23, third structure 122C is configured similarly to
third structure 121C except that third structure 122C includes resistor 9. Third15
structure 122C includes insulating substrate 6, electrode pair 7, metal thin film 8,
resistor 9, and coating material a1. Coating material a1 is used to cover a surface of
metal thin film 8 exposed in the environment.
[0158] With reference to Fig. 20 again, resistance value changes that occur before and
after wire breakage are described using second structure 122B as a typical example.20
In this example, the material of metal thin film 8 in second structure 122B is silver, and
this metal film has the following dimensions; film width “w” of 0.5 mm, film length “l”
of 1 mm, and film thickness “d1” of 5 μm. Further, the material of resistor 9 in
second structure 122B is ruthenium oxide, and its resistance value RR is 400 Ω. Metal
thin film 8 and resistor 9 are connected in parallel to each other. An electric resistivity25
“ρ” of silver included in metal thin film 8 is 1.6 × 10-8 at 20°C.
[0159] In second structure 122B in an environment at 20°C, its initial resistance value
R02 may be calculated using the formula 1 and the following formula 6. Initial
resistance value R02 of second structure 122B thus calculated is substantially equal to a
resistance value R0 of metal thin film 8.30
[0160] R02 = R0 × RR / (R0 + RR) = 6.4 × 10-3Ω ... (Formula 6)
- 33 -
(where R0: resistance value of metal thin film 8 = 1.6 × 10-8 × 1 × 10-3/ (0.5 ×
10-3 × 5 × 10-6) = 6.4 × 10-3Ω, RR = 400 Ω).
[0161] This second structure 122B is kept exposed in the environment to calculate the
resistance value at the time of breakage of metal thin film 8. Metal thin film 8, as
progressively corroded, transforms from the metallic state into a corrosion product.5
Therefore, breakage of metal thin film 8 does not occur physically. The corrosion
product generated then, however, has a resistance 100 thousand times greater than a
typical metal resistance. Thus, metal thin film 8 is electrically insulated, which may
be, in fact, regarded as breakage. With a resistance value R0' of metal thin film 8
being infinite, a resistance value R02' of second structure 122B is calculated using the10
following formula 7. Resistance value R02’ of second structure 122B thus calculated
is substantially equal to resistance value RR of resistor 9 in second structure 122B.
[0162] R02' = R0' × RR / (R0' + RR) = RR / (1 + RR/R0') ≈ RR = 400 Ω ... (Formula 7)
[0163] Thus, initial resistance value R02 of second structure 122B is substantially equal
to resistance value R0 of metal thin film 8, and resistance value R02' of second structure15
122B subsequent to wire breakage is substantially equal to resistance value RR of
resistor 9. The same applies to first structure 122A and third structure 122C. In this
embodiment, the resistance value of resistor 9 in an optional one of three structures 122
is so set that differs from a resistance value of resistor 9 in each of the other structures
and that differs from a total of respective resistance values of resistors 9 in optionally20
selected ones of the other structures. With the resistance values being set to such
values, any structure undergoing wire breakage may be identified from resistance value
changes of sensor body 11A (see Fig. 19).
[0164] Fig. 24 is a drawing that illustrates an exemplified sensor body according to the
fourth embodiment. Sensor body 11A includes three structures 122, resistor 91, and25
wirings 41 and 42.
[0165] First structure 122A includes metal thin film 8, specifically, a thin film made of
copper and further incudes resistor 9. Metal thin film 8 is exposed in the environment.
The resistance value of resistor 9 is set to 200 Ω.
[0166] Second structure 122B includes metal thin film 8, specifically, a thin film made30
of silver and further incudes resistor 9. Metal thin film 8 is exposed in the
- 34 -
environment. The resistance value of resistor 9 is set to 400 Ω.
[0167] Third structure 122C includes metal thin film 8, specifically, a thin film made of
silver and further incudes resistor 9. A surface of metal thin film 8 exposed in the
environment is covered with a coating material including a silicone-based resin. The
resistance value of resistor 9 is set to 800 Ω.5
[0168] The metal thin films of these three structures 122 are all 5 μm in thickness.
The coating material is also 5 μm in thickness. Instead, the metal thin films of these
three structures 122 may have different thicknesses. The metal thin films and the
coating material may have different thicknesses.
[0169] The coating material including a silicone-based resin has a gas permeability10
specific to sublimed sulfur. As a result, a magnitude relation in corrosion resistance
between second structure 122B and third structure 122C differs between an
environment where sublimed sulfur is not present (first environment) and an
environment where sublimed sulfur is present (second or third environment).
[0170] Copper may react more sensitively than silver with the other sulfur-based gases.15
As a result, a magnitude relation in corrosion resistance between first structure 122A
and second structure 122B differs between an environment where a gas included in the
other sulfur-based gases is present (first or third environment) and an environment
where the other sulfur-based gases are not present (second environment).
[0171] Thus, a magnitude relation in corrosion resistance between first structure 122A,20
second structure 122B and third structure 122C differs between the first environment,
the second environment, and the third environment.
[0172] In this embodiment, information on the magnitude relation in corrosion
resistance between three structures 122 for each environment (i.e., corrosion resistance
information) is stored in recorder 30. In this embodiment, analyzer 31 specifies the25
chronological order of wire breakage that occurred by then based on resistance value
changes of sensor body 11A in an environment where sensor 101A (or electric device
900A) is really exposed. Then, analyzer 31 determines the magnitude relation in
corrosion resistance between three structures 122 based on the chronological order of
wire breakage that occurred by then. Then, analyzer 31 identifies the type of any30
corrosive gas based on the determined magnitude relation in corrosion resistance
- 35 -
between three structures 122 and the magnitude relation in corrosion resistance
between three structures 122 for each environment indicated by the corrosion resistance
information.
[0173] The materials and thicknesses of metal thin film 8 and of the coating material
described so far are just a few examples. The materials and thicknesses of metal thin5
film 8 and of the coating material may be set otherwise insofar as the magnitude
relation in corrosion resistance between first structure 122A, second structure 122B and
third structure 122C differs between the first environment, the second environment, and
the third environment.
[0174] The resistance values of resistors 9 of Fig. 24 are illustrated as a few examples.10
The resistance value of resistor 9 in an optional one of three structures 122 is so set that
differs from a resistance value of resistor 9 in each of the other structures and that
differs from a total of respective resistance values of resistors 9 in optionally selected
ones of the other structures.
[0175] The resistance value of resistor 91 illustrated in Fig. 24 is just an example.15
[0176] Next, a process to record resistance value changes is described with reference
mainly to Figs. 19, 24 and 25. Fig. 25 is a flow chart of a process to record resistance
value changes. The process illustrated in Fig. 25 is periodically invoked at predefined
regular intervals from a main routine not illustrated in the drawing and then carried out
by analyzer 31. The steps (hereinafter, simply “S”) are basically actualized through20
software processing by analyzer 31, however, may be actualized through hardware
processing using, for example, an electronic circuit embedded in analyzer 31.
[0177] In S41, analyzer 31 measures the resistance value of sensor body 11A (may be
hereinafter referred to as “combined resistance X”). The resistance value of sensor
body 11A is a combined resistance value in which resistance values of three structures25
122 (including metal thin films 8 and resistors 9), resistor 91, and wirings 41 and 42 are
combined.
[0178] In S42, analyzer 31 specifies one of a plurality of reference resistance ranges
REFn (n is an integer greater than or equal to 1) which is a range including combined
resistance X measured in S41. The same number of reference resistance ranges REFn30
as the number of combination patterns of wire breakage/no wire breakage in the N
- 36 -
number of structures (i.e., Nth power of 2) are set beforehand. In this example, eight
(3rd power of 2) reference resistance ranges (reference resistance ranges REF1 - REF8)
are set beforehand.
[0179] For instance, reference resistance range REF1 is a range of combined resistance
X when no wire breakage has occurred in any structure, which is set to a value5
substantially equal to the value of resistor 91 (100 ≤ X < 300). Reference resistance
range REF2 is a range of combined resistance X when wire breakage has occurred in
first structure 122A, which is set to 300 ≤ X < 500. Reference resistance range REF3
is a range of combined resistance X when wire breakage has occurred in second
structure 122B, which is set to 500 ≤ X < 700. Reference resistance range REF4 is a10
range of combined resistance X when wire breakage has occurred in third structure
122C, which is set to 900 ≤ X < 1100.
[0180] Reference resistance range REF5 is a range of combined resistance X when
wire breakage has occurred in first and second structures 122A and 122B, which is set
to 700 ≤ X < 900. Reference resistance range REF6 is a range of combined resistance15
X when wire breakage has occurred in first and third structures 122A and 122C, which
is set to 1100 ≤ X < 1300. Reference resistance range REF7 is a range of combined
resistance X when wire breakage has occurred in second and third structures 122B and
122C, which is set to 1300 ≤ X < 1500.
[0181] Reference resistance range REF8 is a range of combined resistance X when20
wire breakage has occurred in first structure 122A, second structure 122B and third
structure 122C, which is set to 1500 ≤ X.
[0182] In S43, analyzer 31 writes, as measured data, reference resistance range REFn
specified in S42 and measurement time of combined resistance X in recorder 30.
[0183] When S43 is over, analyzer 31 ends the processing steps of Fig. 25.25
[0184] An analyzing process according to the fourth embodiment is hereinafter
described with reference mainly to Figs. 19, 24 and 26. Fig. 26 is a flow chart of an
exemplified analyzing process according to the fourth embodiment. The process
illustrated in Fig. 26 is periodically invoked at predefined regular intervals from a main
routine not illustrated in the drawing and then carried out by analyzer 31. The30
periodic intervals at which the process of Fig. 26 is invoked may preferably be longer
- 37 -
than the periodic intervals at which the process of Fig. 25 is invoked. The steps
(hereinafter, simply “S”) are basically actualized through software processing by
analyzer 31, however, may be actualized through hardware processing using, for
example, an electronic circuit embedded in analyzer 31.
[0185] In S51, analyzer 31 refers to the measured data stored in recorder 30 (reference5
resistance range REFn and measurement time of combined resistance X) to determine
whether wire breakage has occurred. When the measured data is found to include at
least one of reference resistance ranges REF2 to REF8, analyzer 31 determines that
wire breakage has occurred. When wire breakage has occurred (YES in S51),
analyzer 31 proceeds to S53. When no wire breakage has occurred (NO in S51),10
analyzer 31 proceeds to S52.
[0186] In S52, analyzer 31 determines that no sulfur-based gas is present.
[0187] In S53, analyzer 31 refers to the measured data stored in recorder 30 (reference
resistance range REFn and measurement time of combined resistance X) to specify the
chronological order of wire breakage that occurred by then. In recorder 30, all of15
reference resistance ranges REFn specified by then as well as measurement times of
combined resistance X are stored. This may allow analyzer 31 to know specific
changes of the reference resistance range. Analyzer 31 specifies the chronological
order of wire breakage that occurred by then from the known changes of reference
resistance range.20
[0188] An example is given below, in which reference resistance ranges REF2 and
REF5 are stored in recorder 30, and the measurement time of combined resistance X of
reference resistance range REF2 precedes the measurement time of combined
resistance X of reference resistance range REF5. This example may strongly suggest
that wire breakage occurred in second structure 122B after the occurrence of wire25
breakage in first structure 122A. Then, analyzer 31 determines wire breakage
occurred in second structure 122B after the occurrence of wire breakage in first
structure 122A.
[0189] In S54, analyzer 31 may determine the magnitude relation in corrosion
resistance between three structures 122 based on chronological order of wire breakage30
specified in S53. The corrosion resistance may be lower with an earlier occurrence of
- 38 -
wire breakage. Analyzer 31, therefore, determines the magnitude relation in corrosion
resistance between three structures 122 so that the corrosion resistance is lower with an
earlier occurrence of wire breakage.
[0190] In S55, analyzer 31 identifies the type of any corrosive gas present in an
environment similarly to the first embodiment (see S29 to S35).5
[0191] In S56, analyzer 31 prompts notification device 40 to notify the obtained
content. For example, analyzer 31 displays the content obtained in S52 or S55 on a
liquid crystal display.
[0192] Following on from S52, analyzer 31 may display, on the liquid crystal display,
such a message as “No sulfur-based gas”, “No impact from sulfur-based gas” or10
“Ready for continued use”. Following on from S52, analyzer 31 may not display any
message on the liquid crystal display.
[0193] Following on from S55, analyzer 31 may display, on the liquid crystal display,
such a message as “The corrosive gas is ***” or “Discuss any other cause of corrosion
but sulfur-based gases”.15
[0194] When S56 is over, analyzer 31 ends the processing steps of Fig. 26.
[0195] Notification device 40 may be selected from such devices as LED indicator,
buzzer and speaker.
[0196] Next, verification results on usefulness of sensor 101A according to the fourth
embodiment are hereinafter described. In working examples described below, electric20
device 900A equipped with sensor 101A (inverter in these examples) was exposed in a
corrosive gas-present environment. Sensor 101A includes three structures 122
described above (first structure 122A, second structure 122B, and third structure 122C).
The material of metal thin film 8 in first structure 122A was copper. The material of
metal thin film 8 in second and third structures 122B and 122C was silver. The metal25
thin films 8 of these three structures were all 10 μm in thickness. Coating material a1
of third structure 122C was a silicone-based resin having the oxygen permeability of
31000[cc/m2·day at 20°C (2 mm)] and having the thickness of 10 μm. The resistance
value of resistor 9 in first structure 122A was 200 Ω, the resistance value of resistor 9
in second structure 122B was 400 Ω, the resistance value of resistor 9 in third structure30
122C was 800 Ω, and the resistance value of resistor 91 was 100 Ω.
- 39 -
[0197] Fourth embodiment, first working example
Electric device 900A was exposed in an environment under the condition of
40°C/95% RH/3 ppm H2S. On day 1 after the exposure started, combined resistance
X of sensor body 11A was 100 Ω. At the time, none of the structures had experienced
any wire breakage.5
[0198] On day 6 after the exposure started, combined resistance X was 300 Ω. On
that day, the occurrence of wire breakage in first structure 122A was confirmed. The
resistance value increase from 100 Ω to 300 Ω was thus proven to result from the wire
breakage that occurred in first structure 122A.
[0199] On day 140 after the exposure started, combined resistance X of sensor body10
11A was 700 Ω. At the time, the occurrence of wire breakage in second structure
122B was confirmed, as well as in first structure 122A. The resistance value increase
from 300 Ω to 700 Ω was thus proven to result from the wire breakage that additionally
occurred in second structure 122B.
[0200] This verification result demonstrates that, in an environment where H2S is15
present and S8 is not present (i.e., first environment), the magnitude relation in
corrosion resistance between three structures may be defined as follows; first structure
122A < second structure 122B < third structure 122C.
[0201] Fourth embodiment, second working example
Electric device 900A was exposed in an environment at 75°C where S8 was20
present. On day 1 after the exposure started, combined resistance X of sensor body
11A was 100 Ω. At the time, none of the structures had experienced any wire
breakage.
[0202] On day 4 after the exposure started, combined resistance X of sensor body 11A
was 900 Ω. On that day, the occurrence of wire breakage in third structure 122C was25
confirmed. The resistance value increase from 100 Ω to 900 Ω was thus proven to
result from the wire breakage that occurred in third structure 122C.
[0203] On day 7 after the exposure started, combined resistance X of sensor body 11A
was 1300 Ω. At the time, the occurrence of wire breakage in second structure 122B,
as well as in third structure 122C, was confirmed. The resistance value increase from30
900 Ω to 1300 Ω was thus proven to result from the wire breakage that additionally
- 40 -
occurred in second structure 122B.
[0204] This verification result demonstrates that, in an environment where S8 is present
and H2S is not present (i.e., second environment), the magnitude relation in corrosion
resistance between three structures is defined as follows; first structure 122A > second
structure 122B > third structure 122C.5
[0205] Fourth embodiment, third working example
Electric device 900A was exposed in an environment under the condition of
40°C/95% RH/ (0.2 ppm S8 + 3 ppm H2S). On day 1 after the exposure started,
combined resistance X of sensor body 11A was 100 Ω. At the time, none of the
structures had experienced any wire breakage.10
[0206] On day 6 after the exposure started, combined resistance X of sensor body 11A
was 300 Ω. On that day, the occurrence of wire breakage in first structure 122A was
confirmed. The resistance value increase from 100 Ω to 300 Ω was thus proven to
result from the wire breakage that occurred in first structure 122A.
[0207] On day 8 after the exposure started, combined resistance X of sensor body 11A15
was 1100 Ω. At the time, the occurrence of wire breakage in third structure 122C was
confirmed, as well as in first structure 122A. The resistance value increase from 300
Ω to 1100 Ω was thus proven to result from the wire breakage that additionally
occurred in third structure 122C.
[0208] This verification result demonstrates that, in an environment where S8 and H2S20
coexist and the concentration of H2S is higher than that of S8 (i.e., third environment),
the magnitude relation in corrosion resistance between three structures is defined as
follows; first structure 122A < third structure 122C < second structure 122B.
[0209] The verification results obtained from the first, second and third working
examples of the fourth embodiment demonstrate that electric device 900A may be25
determined as being in the first environment, i.e., the type of corrosive gas present in
the environment may be determined as a gas included in the other sulfur-based gases
when the magnitude relation in corrosion resistance between three structures is defined
as follows; first structure 122A < second structure 122B < third structure 122C.
[0210] These verification results also demonstrate that electric device 900A may be30
determined as being in the second environment, i.e., the type of corrosive gas present in
- 41 -
the environment may be determined as sublimed sulfur when the magnitude relation in
corrosion resistance between three structures is defined as follows; first structure 122A
> second structure 122B > third structure 122C.
[0211] These verification results further demonstrate that electric device 900A may be
determined as being in the third environment, i.e., sublimed sulfur and a gas included in5
the other sulfur-based gases coexist in the environment when the magnitude relation in
corrosion resistance between three structures is defined as follows; first structure 122A
< third structure 122C < second structure 122B.
[0212] According to the fourth embodiment, sensor 101A includes three structures 122,
and the magnitude relation in corrosion resistance between three structures 122 differs10
between first environment, second environment, and third environment. According to
the fourth embodiment, combined resistance X changes as a result of the occurrence of
wire breakage, and the change of combined resistance X that occurred then is stored in
recorder 30. Thus, the chronological order of wire breakage that occurred by then
may be specified, which may allow the magnitude relation in corrosion resistance15
between three structures 122 to be successfully determined. Further, the type of
corrosive gas present in the environment may be identifiable by comparing the
determined magnitude relation in corrosion resistance between three structures 122
with the corrosion resistance information stored in recorder 30. Then, it can be
determined whether one of the first type of corrosive gas and the second type of20
corrosive gas is present or the first type of corrosive gas and the second type of
corrosive gas are coexistent.
[0213] According to the fourth embodiment, the resistance value of resistor 9 may be
set to greater than that of metal thin film 8. Supposing that resistance measurer 20 has
a poor measuring accuracy, failing to detect and measure any minor resistance value25
change of metal thin film 8, a structure with possible wire breakage may be identifiable
based on changes of combined resistance X. Thus, it can be determined whether one
of the first type of corrosive gas and the second type of corrosive gas is present or the
first type of corrosive gas and the second type of corrosive gas are coexistent,
regardless of whether resistance measurer 20 fails to provide a high accuracy in30
measurement.
- 42 -
[0214] Fifth embodiment
In a fifth embodiment of this disclosure, analyzer 31 specifies wire breakage
situation, more specifically, the presence or absence of wire breakage, from resistance
values of the sensor body and identifies the type of corrosive gas present in the
environment based on the specified presence or absence of wire breakage.5
[0215] An electric device equipped with the sensor according to the fifth embodiment
is configured similarly to electric device 900A according to the fourth embodiment (see
Fig. 19). Analyzer 31 according to the fifth embodiment specifies wire breakage
situation from the resistance value of sensor body 11A (combined resistance X)
similarly to analyzer 31 according to the fourth embodiment. In the fifth embodiment,10
analyzer 31 does not write the measured combined resistance X in recorder 30, leaving
no record of combined resistance X. The fifth embodiment fails to specify or grasp
the chronological order of wire breakage. Analyzer 31 of the fifth embodiment,
therefore, identifies the type of corrosive gas present in the environment by determining
whether wire breakage has occurred or not at the present time.15
[0216] The magnitude relation in corrosion resistance between three structures 122 is
known to be similar to the magnitude relation in corrosion resistance between three
structures 121 illustrated in Fig. 12 from the verification results of the first, second and
third working examples of the fourth embodiment. In this embodiment, information
on the magnitude relation in corrosion resistance between three structures 122 for each20
environment (i.e., corrosion resistance information) is stored in recorder 30 likewise.
[0217] An analyzing process according to the fifth embodiment is hereinafter described
with reference mainly to Figs. 19, 24 and 27. Fig. 27 is a flow chart of an exemplified
analyzing process according to the fifth embodiment. The process illustrated in Fig.
27 is periodically invoked at predefined regular intervals from a main routine not25
illustrated in the drawing and then carried out by analyzer 31. The steps (hereinafter,
simply “S”) are basically actualized through software processing by analyzer 31,
however, may be actualized through hardware processing using, for example, an
electronic circuit embedded in analyzer 31.
[0218] In S61, analyzer 31 measures combined resistance X at the time. In S62,30
analyzer 31 specifies reference resistance range REFn relevant to the measured
- 43 -
combined resistance X. S61 and S62 are processing steps similar to S41 and S42.
[0219] In S63, analyzer 31 determines whether wire breakage has occurred or not. In
case reference resistance range REFn specified in S62 is any range but reference
resistance range REF1, analyzer 31 determines that wire breakage has occurred.
When wire breakage has occurred (YES in S63), analyzer 31 proceeds to S65. When5
no wire breakage has occurred (NO in S63), analyzer 31 proceeds to S64.
[0220] In S64, analyzer 31 determines that no wire breakage has occurred.
[0221] In S65, analyzer 31 determines whether wire breakage has occurred in all of the
structures. In case reference resistance range REFn specified in S62 is reference
resistance range REF8, analyzer 31 determines that wire breakage has occurred in all of10
the structures. When wire breakage has occurred in all of the structures (YES in S65),
analyzer 31 proceeds to S66. When wire breakage has not occurred in at least one of
the structures (NO in S65), analyzer 31 proceeds to S67.
[0222] In S66, analyzer 31 determines that “at least one of sublimed sulfur and a gas
included in the other sulfur-based gases”, i.e., “a sulfur-based gas” is present.15
[0223] In S67, analyzer 31 determines the presence or absence of wire breakage in the
structures based on reference resistance range REFn specified in S62.
[0224] In S68, analyzer 31 determines the magnitude relation in corrosion resistance
between three structures 122 based on the presence or absence of wire breakage
determined in S67. Analyzer 31 determines the magnitude relation in corrosion20
resistance between three structures 122, so that any structure determined in S67 as wire
breakage has occurred has a lower corrosion resistance than any other structure
determined otherwise in S67.
[0225] Specifically, when wire breakage has occurred in only first structure 122A,
analyzer 31 determines that first structure 122A has a lower corrosion resistance than25
second structure 122B and third structure 122C.
[0226] When wire breakage has occurred in only second structure 122B, analyzer 31
determines that second structure 122B has a lower corrosion resistance than first
structure 122A and third structure 122C.
[0227] When wire breakage has occurred in only third structure 122C, analyzer 3130
determines that third structure 122C has a lower corrosion resistance than first structure
- 44 -
122A and second structures 122B.
[0228] When wire breakage has occurred in only first structure 122A and second
structure 122B, analyzer 31 determines that first structure 122A and second structure
122B have a lower corrosion resistance than third structure 122C.
[0229] When wire breakage has occurred in only first structure 122A and third5
structure 122C, analyzer 31 determines that first structure 122A and third structure
122C have a lower corrosion resistance than second structure 122B.
[0230] When wire breakage has occurred in only second structure 122B and third
structure 122C, analyzer 31 determines that second structure 122B and third structure
122C have a lower corrosion resistance than first structure 122A.10
[0231] In S69, analyzer 31 refers to the corrosion resistance information stored in
recorder 30 to find and specify an environment consistent with the magnitude relation
in corrosion resistance between three structures 122 determined in S68. When
analyzer 31 fails to specify one environment consistent with the magnitude relation in
corrosion resistance between three structures 122 determined in S68, analyzer 3115
specifies all of the relevant environments.
[0232] In S70, analyzer 31 identifies the type of any corrosive gas present in the
environment based on the environment specified in S69. For example, in case the
environment specified in S69 is the first environment, analyzer 31 identifies the type of
any corrosive gas present in this environment as a gas included in the other sulfur-20
based gases. In case the environment specified in S69 is the second environment,
analyzer 31 identifies the type of any corrosive gas present in this environment as
sublimed sulfur. In case the environment specified in S69 is the third environment,
analyzer 31 identifies the type of any corrosive gas present in this environment as
sublimed sulfur and a gas included in the other sulfur-based gases.25
[0233] In case the environments specified in S69 are the first and third environments,
analyzer 31 determines that a gas included in the other sulfur-based gases is at least
present.
[0234] In S71, analyzer 31 prompts notification device 40 to notify the obtained
content. For example, analyzer 31 displays the content obtained in S64, S66 or S7030
on a liquid crystal display.
- 45 -
[0235] Following on from S64, analyzer 31 may display, on the liquid crystal display,
such a message as “Wire breakage is currently undetectable”.
[0236] Following on from S66, analyzer 31 may display, on the liquid crystal display,
such a message as “A sulfur-based gas is present”.
[0237] Following on from S70, analyzer 31 may display, on the liquid crystal display,5
such a message as “The corrosive gas is ***”. When it is determined that a gas
included in the other sulfur-based gases is at least present in S70, analyzer 31 displays,
on the liquid crystal display, such a message as “a gas included in the other sulfur-
based gases is present, with a possible presence of sublimed sulfur as well”.
[0238] This embodiment, however, fails to specify the chronological order of wire10
breakage that occurred by then in case wire breakage has occurred in two structures.
When, for example, wire breakage has occurred in both of first structure 122A and
second structure 122B, wire breakage in second structure 122B may precede wire
breakage in the other. When, for example, wire breakage has occurred in both of first
structure 122A and third structure 122C, wire breakage in third structure 122C may15
precede wire breakage in the other. When, for example, wire breakage has occurred
in both of second structure 122B and third structure 122C, wire breakage in second
structure 122B may precede wire breakage in the other. When wire breakage has
occurred in two structures, analyzer 31, in view of such possibly different timings of
wire breakage, may display such messages as “The corrosive gas is ***”, and “with a20
possible presence of corrosion factor other than sulfur-based gases”.
[0239] When S71 is over, analyzer 31 ends the processing steps of Fig. 27.
[0240] Notification device 40 may be selected from such devices as LED indicator,
buzzer and speaker.
[0241] Next, verification results on usefulness of sensor 101A according to the fifth25
embodiment are hereinafter described. This verification conducted employed the
same conditions as those used to verify usefulness of the sensor of the fourth
embodiment.
[0242] Fifth embodiment, first working example
Electric device 900A was exposed in an environment under the condition of30
40°C/95% RH/3 ppm H2S. On day 1 after the exposure started, combined resistance
- 46 -
X of sensor body 11A was 100 Ω. At the time, none of the structures had experienced
any wire breakage.
[0243] On day 6 after the exposure started, combined resistance X was 300 Ω. On
that day, the occurrence of wire breakage in first structure 122A was confirmed. The
resistance value increase from 100 Ω to 300 Ω was thus proven to result from the wire5
breakage that occurred in first structure 122A.
[0244] Further, in an environment where H2S is present and S8 is not present (i.e., first
environment), first structure 122A was proven to have a lowest corrosion resistance
among the three structures 122.
[0245] On day 140 after the exposure started, combined resistance X of sensor body10
11A was 700 Ω. At the time, the occurrence of wire breakage in second structure
122B was confirmed, as well as in first structure 122A. The resistance value increase
from 100 Ω to 700 Ω was thus proven to result from the wire breakage that occurred in
first structure 122A and second structure 122B.
[0246] Further, in an environment where H2S is present and S8 is not present (i.e., first15
environment), first structure 122A and second structure 122B, among three structures
122, were proven to have a lower corrosion resistance than that of third structure 122C.
[0247] Fifth embodiment, second working example
Electric device 900A was exposed in an environment at 75°C where S8 was
present. On day 1 after the exposure started, combined resistance X of sensor body20
11A was 100 Ω. At the time, none of the structures had experienced any wire
breakage.
[0248] On day 4 after the exposure started, combined resistance X of sensor body 11A
was 900 Ω. On that day, the occurrence of wire breakage in third structure 122C was
confirmed. The resistance value increase from 100 Ω to 900 Ω was thus proven to25
result from the wire breakage that occurred in third structure 122C.
[0249] Further, in an environment where S8 is present and H2S is not present (i.e.,
second environment), third structure 122C was proven to have a lowest corrosion
resistance among the three structures 122.
[0250] On day 7 after the exposure started, combined resistance X of sensor body 11A30
was 1300 Ω. At the time, the occurrence of wire breakage in second structure 122B,
- 47 -
as well as in third structure 122C, was confirmed. The resistance value increase from
100 Ω to 1300 Ω was thus proven to result from the wire breakage that occurred in
second structure 122B and third structure 122C.
[0251] Further, in an environment where S8 is present and H2S is not present (i.e.,
second environment), second structure 122B and third structure 122C, among three5
structures 122, were proven to have a lower corrosion resistance than that of first
structure 122A.
[0252] Fifth embodiment, third working example
Electric device 900A was exposed in an environment under the condition of
40°C/95% RH/ (0.2 ppm S8 + 3 ppm H2S). On day 1 after the exposure started,10
combined resistance X of sensor body 11A was 100 Ω. At the time, none of the
structures had experienced any wire breakage.
[0253] On day 6 after the exposure started, combined resistance X of sensor body 11A
was 300 Ω. On that day, the occurrence of wire breakage in first structure 122A was
confirmed. The resistance value increase from 100 Ω to 300 Ω was thus proven to15
result from the wire breakage that occurred in first structure 122A.
[0254] Further, in an environment where S8 and H2S coexist and the concentration of
H2S is higher than that of S8 (i.e., third environment), first structure 122A was proven
to have a lowest corrosion resistance among the three structures 122.
[0255] On day 8 after the exposure started, combined resistance X of sensor body 11A20
was 1100 Ω. At the time, the occurrence of wire breakage in third structure 122C was
confirmed, as well as in first structure 122A. The resistance value increase from 100
Ω to 1100 Ω was thus proven to result from the wire breakage that occurred in first
structure 122A and third structure 122C.
[0256] This verification result demonstrates that, in an environment where S8 and H2S25
coexist and the concentration of H2S is higher than that of S8 (i.e., third environment),
first structure 122A and third structure 122C, among three structures 122, were proven
to have a lower corrosion resistance than second structure 122B.
[0257] The verification results obtained from the first, second and third working
examples of the fifth embodiment demonstrate that electric device 900A may be30
determined as being in the first environment or in the third environment, i.e., at least a
- 48 -
gas included in the other sulfur-based gases is present in the environment when first
structure 122A, among the three structures 122, has a lowest corrosion resistance.
[0258] These verification results also demonstrate that electric device 900A may be
determined as being in the second environment, i.e., the type of corrosive gas present in
the environment may be determined as sublimed sulfur when third structure 122C,5
among the three structures 122, has a lowest corrosion resistance.
[0259] These verification results further demonstrate that electric device 900A may be
determined as being in the first environment, i.e., the type of corrosive gas present in
the environment may be determined as a gas included in the other sulfur-based gases
when first structure 122A and second structure 122B, among the three structures 122,10
have a lower corrosion resistance than third structure 122C.
[0260] These verification results further demonstrate that electric device 900A may be
determined as being in the second environment, i.e., the type of corrosive gas present in
the environment may be determined as sublimed sulfur when second structure 122B
and third structure 122C, among the three structures 122, have a lower corrosion15
resistance than first structure 122A.
[0261] These verification results further demonstrate that electric device 900A may be
determined as being in the third environment, i.e., the types of corrosive gases present
in the environment may be determined as sublimed sulfur and a gas included in the
other sulfur-based gases when first structure 122A and third structure 122C, among the20
three structures 122, have a lower corrosion resistance than second structure 122B.
[0262] According to the fifth embodiment, sensor 101A includes three structures 122,
and the magnitude relation in corrosion resistance between three structures 122 differs
between first environment, second environment, and third environment. According to
the fifth embodiment, combined resistance X changes in response to the occurrence of25
wire breakage. Thus, whether wire breakage has occurred or not may be successfully
determined, and the magnitude relation in corrosion resistance between three structures
122 may also be successfully determined. Further, the type of corrosive gas present in
the environment may be identifiable by comparing the determined magnitude relation
in corrosion resistance between three structures 122 with the corrosion resistance30
information stored in recorder 30. Then, it can be determined whether one of the first
- 49 -
type of corrosive gas and the second type of corrosive gas is present or the first type of
corrosive gas and the second type of corrosive gas are coexistent.
[0263] Sixth Embodiment
A sixth embodiment of this disclosure is targeted for more types of corrosive
gases than in first to fifth embodiments. To be specific, target corrosive gases5
according to the sixth embodiment include sulfur-based gases and chlorine gas.
[0264] An electric device according to the sixth embodiment is configured similarly to
electric device 900 according to the first embodiment (see Fig. 1) except that the
sensor’s body includes more structures than in the earlier embodiments. Fig. 28 is a
drawing that illustrates an exemplified sensor body according to the sixth embodiment.10
[0265] A sensor body 11B according to the sixth embodiment includes five structures
(first structure 121A, second structure 121B, third structure 121C, fourth structure
121D, and fifth structure 121E), wirings 4, and terminal changer 52. In the
description given below, first structure 121A, second structure 121B, third structure
121C, fourth structure 121D and fifth structure 121E may be collectively referred to as15
five structures 123.
[0266] Wirings 4 include a wiring 41, five wirings 42 and a wiring 43. Wirings 4 are
routed on a circuit board. Five wirings 42 are routed correspondingly to five
structures 123. The structures are each disposed so that wiring 41 is connectable to a
corresponding one of wirings 42 and are mounted onto wirings 41 and 42 by soldering.20
[0267] First structure 121A, second structure 121B and third structure 121C are
configured as described thus far. Fourth structure 121D and fifth structure 121E are
similar to first structure 121A except that metal thin films in these structures are made
of different metallic materials.
[0268] To be specific, fourth structure 121D includes a metal thin film, specifically, a25
thin film made of tin, and this thin film is exposed in an environment. Tin is an
example of the “third metallic material” as described herein. Chlorine gas
preferentially corrodes tin.
[0269] Fifth structure 121E includes a metal thin film, specifically, a thin film made of
nickel, and this thin film is exposed in the environment. Nickel is corrodible by sulfur30
dioxide and also by chlorine gas.
- 50 -
[0270] The metal thin films of these five structures 123 are all 10 μm in thickness.
The coating material is also 10 μm in thickness. Instead, the metal thin films of these
five structures 123 may have different thicknesses. The metal thin films and the
coating material may have different thicknesses.
[0271] As described above, the magnitude relation in corrosion resistance between first5
structure 121A, second structure 121B and third structure 121C differs between the first
environment, the second environment, and the third environment.
[0272] In this embodiment, as information on the magnitude relation in corrosion
resistance between first structure 121A, second structure 121B and third structure 121C
for each environment (i.e., corrosion resistance information), the magnitude relation10
illustrated in Fig. 12 is stored in recorder 30. In this embodiment, analyzer 31
calculates the corrosion speed of each of five structures 123 in an environment where
sensor 101 (or electric device 900) is really exposed.
[0273] In view of the fact that chlorine gas preferentially corrodes tin, analyzer 31
determines whether chlorine gas is present based on the corrosion speed of fourth15
structure 121D. In view of the fact that nickel is corrodible by sulfur dioxide and also
by chlorine gas, analyzer 31 determines whether sulfur dioxide is present based on the
corrosion speeds of fourth structure 121D and fifth structure 121E.
[0274] Analyzer 31 determines the magnitude relation in corrosion resistance between
first structure 121A, second structure 121B and third structure 121C based on the20
corrosion speeds of these structures and then determines whether one of sublimed
sulfur and hydrogen sulfide is present or sublimed sulfur and hydrogen sulfide are
coexistent as described in the first embodiment.
[0275] The materials and thicknesses of the metal thin film and of the coating material
described so far are just a few examples. The materials and thicknesses of the metal25
thin film and of the coating material may be set otherwise insofar as the magnitude
relation in corrosion resistance between first structure 121A, second structure 121B and
third structure 121C differs between the first environment, the second environment and
the third environment.
[0276] An analyzing process according to the sixth embodiment is described below30
with reference to Figs. 1 and 28 to 29. Fig. 29 is a flow chart of an exemplified
- 51 -
analyzing process according to the sixth embodiment. The process illustrated in Fig.
29 is periodically invoked at predefined regular intervals from a main routine not
illustrated in the drawing and then carried out by analyzer 31. The steps (hereinafter,
simply “S”) are basically actualized through software processing by analyzer 31,
however, may be actualized through hardware processing using, for example, an5
electronic circuit embedded in analyzer 31.
[0277] In S81, analyzer 31 calculates the corrosion speeds of five structures 123 using
the method described in the first embodiment or second embodiment and then writes
the calculated corrosion speeds in recorder 30.
[0278] In S82, analyzer 31 extracts, from recorder 30, the latest corrosion speeds of10
these five structures 123.
[0279] In S83, analyzer 31 determines whether corrosion speed V121D of fourth
structure 121D is zero. S83 is a step of determining whether chlorine gas is present.
It can be determined that chlorine gas is not present when corrosion speed of fourth
structure 121D including a tin-made thin film preferentially corroded by chlorine gas is15
zero. When corrosion speed V121D is zero (YES in S83), analyzer 31 proceeds to S85.
When corrosion speed V121D is not zero (NO in S83), analyzer 31 proceeds to S84.
[0280] In S84, analyzer 31 determines that chlorine gas is present. Chlorine gas
corrodes most of the metallic materials, which makes it difficult to accurately evaluate
impacts of any other corrosive gases but chlorine gas. When the presence of chlorine20
gas is confirmed, therefore, analyzer 31 does not determine whether any other corrosive
gases but chlorine gas is present.
[0281] In S85, analyzer 31 determines whether corrosion speed V121E of fifth structure
121E is zero. S85 is a step of determining whether sulfur dioxide is present. Nickel
is corrodible by sulfur dioxide and also by chlorine gas. S85 is performed in a case of25
YES in S83, i.e., in the absence of chlorine gas. Thus, whether sulfur dioxide is
present may be determined based on corrosion speed V121E. When corrosion speed
V121E is zero, it can be determined that sulfur dioxide is not present. When corrosion
speed V121E is zero (YES in S85), analyzer 31 proceeds to S87. When corrosion speed
V121E is not zero (NO in S85), analyzer 31 proceeds to S86.30
[0282] In S86, analyzer 31 determines that sulfur dioxide is present. Copper is
- 52 -
corrodible by sulfur dioxide, whereas silver is hardly affected by sulfur dioxide.
When the presence of sulfur dioxide is confirmed, therefore, analyzer 31 further
determines whether sublimed sulfur is coexistent with sulfur dioxide based on the
corrosion speeds of second structure 121B and third structure 121C (S88 - S92).
[0283] In S87, analyzer 31 carries out S28 to S35 described in the first embodiment5
(see Fig. 15) to determine the presence or absence of hydrogen sulfide and sublimed
sulfur. In the sixth embodiment, in S30, analyzer 31 identifies the type of corrosive
gas present in the environment as hydrogen sulfide. In the sixth embodiment, in S34,
analyzer 31 identifies the types of corrosive gases present in the environment as
sublimed sulfur and hydrogen sulfide.10
[0284] In S88, analyzer 31 determines whether corrosion speeds V121B and V121C are
both zero. When corrosion speeds V121B and V121C are both zero (YES in S88),
analyzer 31 proceeds to S89. When at least one of corrosion speeds V121B and V121C is
not zero (NO in S88), analyzer 31 proceeds to S90.
[0285] In S89, analyzer 31 identifies the type of corrosive gas present in the15
environment as sulfur dioxide, determining that neither of hydrogen sulfide nor
sublimed sulfur is present in the environment.
[0286] In S90, analyzer 31 determines whether corrosion speed V121B > corrosion
speed V121C is satisfied. The relation of corrosion speed V121B > corrosion speed V121C
may be satisfied when the magnitude relation in corrosion resistance between second20
structure 121B and third structure 121C is defined as follows; second structure 121B <
third structure 121C, i.e., sensor 101 (or electric device 900) is exposed in the first
environment. When corrosion speed V121B > corrosion speed V121C is satisfied (YES
in S90), analyzer 31 proceeds to S91. When corrosion speed V121B > corrosion speed
V121C is not satisfied (NO in S90), analyzer 31 proceeds to S92.25
[0287] In S91, analyzer 31 determines that hydrogen sulfide may possibly be present,
along with sulfur dioxide, in the environment. Specifically, analyzer 31 determines
that, in the environment, sulfur dioxide is present and sublimed sulfur is not present,
and hydrogen sulfide may be present in addition to sulfur dioxide.
[0288] In S92, analyzer 31 determines that sublimed sulfur is present, along with sulfur30
dioxide, in the environment.
- 53 -
[0289] In S93, analyzer 31 prompts notification device 40 to notify the obtained
content. For example, analyzer 31 displays the content obtained in S84, S87, S89,
S91 or S92 on a liquid crystal display.
[0290] Following on from S84, analyzer 31 may display, on the liquid crystal display,
such a message as “Chlorine gas is present”.5
[0291] Following on from S87, analyzer 31 may display, on the liquid crystal display,
such a message as “The corrosive gas is ***” or “Discuss any other cause of corrosion
but sulfur-based gases”.
[0292] Following on from S89, analyzer 31 may display, on the liquid crystal display,
such a message as “Sulfur dioxide is present, and sublimed sulfur and hydrogen sulfide10
is not present”.
[0293] Following on from S91, analyzer 31 may display, on the liquid crystal display,
such a message as “Hydrogen sulfide may possibly be present, along with sulfur
dioxide, in the environment”.
[0294] Following on from S92, analyzer 31 may display, on the liquid crystal display,15
such a message as “Sublimed sulfur is present, along with sulfur dioxide, in the
environment”.
[0295] When S93 is over, analyzer 31 ends a sequence of steps illustrated in Fig. 29.
[0296] Notification device 40 may be selected from such devices as LED indicator,
buzzer and speaker.20
[0297] The sixth embodiment may be thus allowed to not only determine whether one
of the first type of corrosive gas and the second type of corrosive gas is present or the
first type of corrosive gas and the second type of corrosive gas are coexistent but also
determine whether a third type of corrosive gas exists.
[0298] Thus far were described various embodiments of the technology disclosed25
herein. As in the description given so far, it can be determined whether one of the
first type of corrosive gas and the second type of corrosive gas is present or the first
type of corrosive gas and the second type of corrosive gas are coexistent. The
embodiments disclosed herein described how to determine whether one of sublimed
sulfur and a gas included in the other sulfur-based gases is present or sublimed sulfur30
and a gas included in the other sulfur-based gases are coexistent.
- 54 -
[0299] The other sulfur-based gases and sublimed sulfur corrode similar types of
metals. This may be a problem with the technologies described in patent literatures 1
and 2 (PTL 1 and 2), failing to determine whether one of sublimed sulfur and a gas
included in the other sulfur-based gases is present or sublimed sulfur and a gas included
in the other sulfur-based gases are coexistent. Gas-induced corrosion factors may5
typically include metal-corrosive gas combination (metal corrosiveness), and corrosive
gas concentration, temperature, and humidity. This may be directly applied to
corrosiveness induced by hydrogen sulfide or sulfur dioxide, in which case corrosion
speed increases with a greater value of each corrosion factor. On the other hand,
corrosion induced by sublimed sulfur may be hardly affected by humidity. One way10
to improve environmental corrosiveness may be humidity reduction using air
conditioning. This may be useful for hydrogen sulfide and sulfur dioxide but may
hardly have any effect on sublimed sulfur. Thus, whether sublimed sulfur and the
other sulfur-based gases are coexistent with each other may be useful information for
improvement of environmental corrosiveness. As disclosed herein, it can be15
determined whether one of sublimed sulfur and a gas included in the other sulfur-based
gases is present or sublimed sulfur and a gas included in the other sulfur-based gases
are coexistent, which may offer information useful for improvements of environmental
corrosiveness.
[0300] All of the embodiments are disclosed herein by way of illustration and example20
only and should not be construed as limiting by any means the scope of this disclosure.
The scope of this disclosure is solely defined by the appended claims and is intended to
cover the claims, equivalents, and all of possible modifications made without departing
the scope of this disclosure.
REFERENCE SIGNS LIST25
[0301] 3: circuit board, 4, 41, 42, 43: wiring, 5: solder, 6: insulating substrate, 7:
electrode pair, 8: metal thin film, 9, 91: resistor, 11, 11A, 11B: sensor body, 12:
temperature-humidity sensor, 20: resistance measurer, 30: recorder, 31: analyzer, 40:
notification device, 52: terminal changer, 71: first electrode, 72: second electrode, 90:
electric device body, 101, 101A: sensor, 121A, 122A: first structure, 121B, 122B:30
second structure, 121C, 122C: third structure, 121D: fourth structure, 121E: fifth
- 55 -
structure, 201: voltmeter, 202: ammeter, 900, 900A: electric device, a1: coating
material
- 56 -
WE CLAIM:
[Claim 1] A sensor to identify a type of a corrosive gas present in an
environment, the type of the corrosive gas at least including a first type and a second
type, the sensor comprising:5
a sensor body comprising at least three structures;
a measurer to measure a resistance value of each of the at least three structures
or a resistance value of the sensor body;
an analyzer to identify the type of the corrosive gas present in the environment
based on the resistance value measured by the measurer and corrosion resistance10
information that represents a magnitude relation in corrosion resistance between the at
least three structures for each environment; and
a notification device to notify a content identified by the analyzer,
the at least three structures comprising:
a first structure comprising a thin film including a first metallic material, the15
thin film being exposed in the environment;
a second structure comprising a thin film including a second metallic material
that differs from the first metallic material, the thin film being exposed in the
environment; and
a third structure comprising a thin film including the second metallic material, a20
surface of the thin film exposed in the environment being covered with a coating
material,
the corrosive gas of the first type and the corrosive gas of the second type each
causing corrosion of the first metallic material and the second metallic material,
wherein25
the magnitude relation in corrosion resistance between the at least three
structures differs between a first environment, a second environment, and a third
environment,
the corrosive gas of the first type is present and the corrosive gas of the second
type is not present in the first environment,30
the corrosive gas of the second type is present and the corrosive gas of the first
- 57 -
type is not present in the second environment, and
the corrosive gas of the first type and the corrosive gas of the second type are
both present in the third environment.
[Claim 2] The sensor according to claim 1, wherein5
the measurer measures the resistance value of each of the at least three
structures,
the analyzer calculates a corrosion speed or a corrosion ratio of each of the at
least three structures based on the resistance value measured by the measurer,
the analyzer determines the magnitude relation in corrosion resistance between10
the at least three structures based on the calculated corrosion speed or the calculated
corrosion ratio, and
the analyzer identifies the type of the corrosive gas present in the environment
based on the corrosion resistance information and the determined magnitude relation in
corrosion resistance between the at least three structures.15
[Claim 3] The sensor according to claim 2, further comprising a storage in
which the resistance value measured by the measurer and measurement time when the
resistance value was measured by the measurer are stored in association with each other,
wherein20
the measurer measures the resistance value of each of the at least three
structures periodically at predefined intervals, and
the analyzer calculates the corrosion speed or the corrosion ratio of each of the
at least three structures based on a resistance value measured at a first measurement
time and a resistance value measured at a second measurement time that is an arbitrary25
time before the first measurement time.
[Claim 4] The sensor according to claim 2 or 3, wherein
the analyzer further calculates a concentration of the corrosive gas present in the
environment based on a temperature in the environment, a humidity in the environment,30
and the calculated corrosion speed, and
- 58 -
the notification device further notifies the concentration of the corrosive gas
calculated by the analyzer.
[Claim 5] The sensor according to claim 4, wherein
the analyzer calculates the concentration of the corrosive gas present in the5
environment by substituting the temperature in the environment, the humidity in the
environment, and the calculated corrosion speed in a formula, and
the formula is formulated using analysis of variance based on corrosion speeds
of the thin film obtained in a plurality of model environments that differ in at least one
of a temperature, a humidity, and a concentration of the corrosive gas.10
[Claim 6] The sensor according to claim 1, wherein
each of the at least three structures further comprises a resistor connected in
parallel to the thin film,
the resistor of an optional one of the at least three structures has a resistance15
value that differs from a resistance value of a resistor in each of the rest of the at least
three structures and that differs from a total of respective resistance values of resistors
in optionally selected ones of the rest of the at least three structures,
the measurer measures a resistance value of the sensor body,
the analyzer specifies wire breakage situation in the at least three structures20
based on the resistance value measured by the measurer,
the analyzer determines the magnitude relation in corrosion resistance between
the at least three structures based on the specified wire breakage situation, and
the analyzer identifies the type of the corrosive gas present in the environment
based on the corrosion resistance information and the determined magnitude relation in25
corrosion resistance between the at least three structures.
[Claim 7] The sensor according to claim 6, wherein the wire breakage
situation is a chronological order of occurrence of wire breakage in the at least three
structures.30
- 59 -
[Claim 8] The sensor according to claim 6, wherein the wire breakage
situation is presence or absence of wire breakage in the at least three structures.
[Claim 9] The sensor according to one of claims 1 to 5, wherein
the type of the corrosive gas further includes a third type,5
the at least three structures further comprise a fourth structure comprising a thin
film including a third metallic material that differs from the first metallic material and
the second metallic material, the thin film being exposed in the environment,
the corrosive gas of the third type preferentially causes corrosion of the third
metallic material.10
[Claim 10] The sensor according to one of claims 1 to 9, wherein
the coating material decreases the corrosion speed of the thin film covered with
the coating material in the first environment,
the coating material increases the corrosion speed of the thin film covered with15
the coating material in the second environment and the third environment, and
the first metallic material has a lower corrosion resistance to the corrosive gas
of the first type than the second metallic material.
[Claim 11] The sensor according to one of claims 1 to 10, wherein the coating20
material includes a silicone-based resin.
[Claim 12] The sensor according to one of claims 1 to 11, wherein the thin
films in the at least three structures are equal in thickness.
25
- 60 -
[Claim 13] An electric device comprising the sensor according to one of