SPECIFICATION
TITLE OF THE INVENTION
EXHAUST GAS ANALYZING SYSTEM
Technical Field
[0001]
The present invention relates to a gas analyzer and a gas analyzing
system for measuring particulate matter contained in an exhaust gas
discharged from an engine.
Background Art
[0002]
In order to analyze a gas to be measured (referred to as
"measurement target gas" hereinafter) flowing through a measurement
target gas flow passage, if a part thereof is shunted to be measured, a flow
rate in the measurement target gas flow passage is reduced in
correspondence with a shunted flow rate, and this affects a control of the
measurement target gas and its own and other measurements and may
likely lead to a trouble in some cases.
[0003]
For example, in Patent Literature 1, disclosed is a configuration that
an exhaust gas discharged from an internal combustion engine is diluted
with a dilution gas and the diluted exhaust gas (i.e., measurement target
gas) is led to flow into a mini-tunnel (i.e., measurement target gas flow
passage) and a part of the diluted exhaust gas is shunted to be led to a smoke
particle measurement device. In this smoke particle measurement device,

the smoke particles (also, referred to as "particulate matter" hereinafter) contained in the diluted exhaust gas are collected by a collecting filter so as to measure a mass thereof.
[4]
In this configuration, by locating a CVS device downstream of the mini-tunnel, the flow rate of the diluted exhaust gas flowing in the mini-tunnel is controlled to be constant and an introduction flow rate of the exhaust gas into the mini-tunnel can be controlled. This is because, by controlling the introduction flow rate of the dilution gas into the mini-tunnel, the introduction flow rate of the exhaust gas into the mini-tunnel is indirectly controlled.
[5]
By the way, the flow rate control mentioned above is implemented on the premise that the flow rate of the gas to be introduced into the mini-tunnel, i.e., measurement target gas flow passage is equal to a flow rate of the gas derived therefrom. Therefore, if the smoke particle measurement device takes in a part of the diluted exhaust gas from the mini-tunnel by shunting, there occurs an error in the introduction flow rate of the exhaust gas into the mini-tunnel accordingly, and this may also lead to occurrence of an error in a control of a dilution ratio of the exhaust gas and a measurement in the CVS device and the like.
[6]
Therefore, in Patent Literature 1, the diluted exhaust gas derived from the smoke particle measurement device after the smoke particles are
collected is entirely led to reflow to the mini-tunnel so as to eliminate the

error. In Patent Literature 1, as described in the second paragraph of
column 2 at page 4 and Fig. 1 therein, prior to lead the diluted exhaust gas
from the smoke particle measurement device to reflow, an appropriate flow
rate of air is previously rendered flowing in a reflow passage, and when the
diluted exhaust gas is rendered to flow back, a valve is switched to shut off
the air. It seems that a large pressure fluctuation may not occur in the
mini-tunnel at the time of starting the reflow.
[7]
However, as disclosed in Patent Literature 1, if it is configured that
the measurement target gas subjected to a measurement can be returned as
it is to the flow passage of the measurement target gas, the measurement
errors etc. can be avoided by forming the reflow, but there may be
nevertheless a case where the measurement target gas cannot be returned to
the flow passage of the measurement target gas in such a case where the
measurement target gas is diluted or absorbed according to a measurement
device.
[8]
For example, in a particulate matter counting device for counting the
number of the particulate matter, since the acquired measurement target
gas is diluted within the device, the measurement target gas cannot be
returned as it is. Conventionally, since the flow rate of the measurement
target gas to be acquired by such a particulate matter counting device is not
so large in amount compared to a flow rate of the measurement target gas
flowing through the flow passage of the measurement target gas, if a small in
amount, the error can be suppressed within a tolerance range even if the

measurement target gas is not returned. However, in recent years, it is
required to further improve a measurement accuracy and in the case where
the flow rate of the measurement target gas flowing through the flow
passage of the measurement target gas such as a micro-tunnel, it becomes
impossible to suppress an error of such as a dilution ratio in an admissible
range due to the fact that the measurement target gas cannot be returned to
the source flow passage.
[9]
To give a specific numerical example, conventionally, the flow rate of
the measurement target gas (diluted exhaust gas) acquired by, e.g., the
particulate matter counting device is in a range of 0.1 to 0.5 L/min and the
flow rate of the diluted exhaust gas flowing in the CVS device is set to 50
L/min. Then, there may occur an error in a dilution ratio of the diluted
exhaust gas in a degree of 1% (=0.5/50) at the maximum. In recent years,
however, since a tolerance error of the dilution ratio is required to be within
0.5% and in some cases within 0.1%, the error of 1% mentioned above
exceeds the admissible range.
Citation List
Patent Literature
[10]
Patent Literature l: JP-A-Heisei 03-218436
Summary of Invention
Technical Problem
[0011]
The present invention has been made to solve the problem mentioned

above, and an essential object thereof is to provide a gas analyzer and a gas
analyzing system for introducing and analyzing a part of a measurement
target gas flowing through a flow passage of the measurement target gas,
wherein, even though the introduced measurement target gas is diluted and
absorbed, a flow rate in the flow passage of the measurement target gas can
be compensated so as to ensure accuracy in controlling the measurement
target gas flowing through the measurement target gas flow passage and
accuracy in its own and other measurements.
Solution to Problem
[0012]
That is, a gas analyzer according to one aspect of the present
invention includes^ a gas introduction port communicating with a shunt
point provided in a measurement target gas flow passage so that a part of
the measurement target gas flowing through the measurement target gas
flow passage is introduced; an object measurement device adapted to acquire
the measurement target gas introduced from the gas introduction port so as
to measure a quantity or concentration of a measurement object contained in
the measurement target gas; an acquired gas flow rate measurement device
adapted to measure a flow rate of the measurement target gas acquired by
the object measurement device; and a gas supply device adapted to supply
another gas of a flow rate equal to the gas flow rate measured by the
acquired gas flow rate measurement device to a downstream side of the
shunt point in the measurement target gas flow passage.
[0013]
A gas analyzing system according to another aspect of the present

invention includes: a measurement target gas flow passage in which a measurement target gas flows! a constant flow rate instrument provided on the measurement target gas flow passage in order to keep a constant flow rate of the measurement target gas flowing through the measurement target gas flow passage so that the constant flow rate of the measurement target gas is passed; a branched flow passage branched from a shunt point provided in an upstream side of the constant flow rate instrument in the measurement target gas flow passage,' a gas introduction port connected to the branched flow passage so that a part of the measurement target gas is introduced; an object measurement device adapted to acquire the measurement target gas introduced from the gas introduction port so as to measure a quantity or concentration of a measurement object contained in the measurement target gas! an acquired gas flow rate measurement device adapted to measure a flow rate of the measurement target gas acquired by the object measurement device,' and a gas supply device adapted to supply another gas of a flow rate equal to the gas flow rate measured by the acquired gas flow rate measurement device to a portion between a downstream side of the shunt point and an upstream side of the constant flow rate instrument in the measurement target gas flow passage. [0014]
According to the present invention described above, even though the
object measurement device is adapted to dilute and absorb the acquired
measurement target gas, since another gas having a flow rate equal to the
acquired flow rate is supplied to the measurement target gas flow passage,
the flow rate introduced into the measurement target gas flow passage and

the flow rate derived therefrom are matched so that it becomes possible to
ensure accuracy in controlling the flow rate of the gas introduced into the
measurement target gas flow passage and derived therefrom as well as
measurement accuracy of the measurement object.
[15]
In the object measurement device, it is preferable that, in the case
where a part of the measurement target gas introduced from the gas
introduction port is acquired, another gas is added to the rest of the
measurement target gas introduced from the gas introduction port so as to
supply the resultant gas to the downstream side of the shunt point in the
measurement target gas flow passage. This is because the components of
the supplied gas are close to those of the original gas as possible so that an
effect on the measurement accuracy in such a case of setting, e.g., another
measurement device can be minimized and the gas flow rate can be more
accurately controlled.
[16]
As a specific aspect for attaining a remarkable effect of the present
invention, it may be exemplified to have a configuration that includes: an
exhaust gas flow passage into which a part of an exhaust gas exhausted from
an internal combustion engine is introduced; a dilution gas flow passage into
which a dilution gas is introduced in order to dilute the exhaust gas; a
measurement target gas flow passage in which the exhaust gas flowing into
the exhaust gas flow passage and the dilution gas flowing into the dilution
gas flow passage are joined together and a resultant mixed gas thereof
serving as a measurement target gas flows therein! a constant flow rate

instrument provided on the measurement target gas flow passage in order to
keep a constant flow rate of the measurement target gas flowing through the
measurement target gas flow passage so that the constant flow rate of the
measurement target gas is passed; a branched flow passage branched from a
shunt point provided in an upstream side of the constant flow rate
instrument in the measurement target gas flow passage; a gas introduction
port connected to the branched flow passage so that a part of the
measurement target gas is introduced; an object measurement device
adapted to acquire the measurement target gas introduced from the gas
introduction port so as to measure a quantity or concentration of a
measurement object contained in the measurement target gas.' an acquired
gas flow rate measurement device adapted to measure a flow rate of the
measurement target gas acquired by the object measurement device; and a
gas supply device adapted to supply another gas of a flow rate equal to the
gas flow rate measured by the acquired gas flow rate measurement device to
a portion between a downstream side of the shunt point and an upstream
side of the constant flow rate instrument in the measurement target gas flow
passage.
[0017]
According to the present invention, measurement accuracy of other
measurement devices can be also improved. For example, the present
invention may have a configuration that further includes: a flow rate control
device adapted to control an inflow rate of the exhaust gas by controlling an
inflow rate of the dilution gas so as to keep a flow rate ratio to be constant
between the flow rate of the exhaust gas exhausted from the internal

combustion engine and the exhaust gas flowing into the exhaust gas flow
passage," and a collecting filter for passing through the measurement target
gas flowing in a downstream side of the branched point of the measurement
target gas flow passage and collecting particulate matter contained in the
measurement target gas, so that a mass of the particulate matter contained
in the exhaust gas exhausted from the internal combustion engine can be
calculated based on the mass of the particulate matter collected by the
collecting filter and the flow rate ratio. With this configuration, the inflow
rate of the exhaust gas can be accurately controlled and accordingly, it
becomes also possible to improve the measurement accuracy of measuring a
mass of the particulate matter contained in the exhaust gas by a filter
collecting method.
[0018]
As a specific example of the object measurement device, it may be
exemplified to have a configuration that includes a dilution mechanism for
diluting the acquired measurement target gas and a particle number
counting mechanism for counting the number of particles of the particulate
matter contained in the measurement target gas diluted by the dilution
mechanism.
Advantageous Effects of Invention
[0019]
According to the present invention with the configuration as
described above, even though the object measurement device is adapted to
dilute and absorb the acquired measurement target gas, since another gas
having a flow rate equal to the acquired flow rate is supplied to the

measurement target gas flow passage, the flow rate introduced into the
measurement target gas flow passage and the flow rate derived therefrom
are matched so that it becomes possible to ensure accuracy in controlling the
flow rate of the gas introduced into the measurement target gas flow passage
and derived therefrom as well as measurement accuracy of the measurement
object.
Brief Description of Drawings
[0020]
Fig. 1 is an overall configuration diagram of a gas analyzing system
according to one embodiment of the present invention;
Fig. 2 is an internal fluid circuit diagram of a gas analyzer in the
same embodiment; and
Fig 3 is an internal fluid circuit diagram of a gas analyzer according
to another embodiment of the present invention.
Description of Embodiments
[0021]
The following describes one embodiment of a gas analyzing system
100 according to the present invention referring to the accompanying
drawings.
The gas analyzing system 100 according to the present embodiment
is adapted to measure particulate matter (PM) contained in an exhaust gas
discharged from an internal combustion engine Eg. As shown in Fig. 1, the
device 100 basically includes a flow rate control mechanism 1 which is
adapted to produce a mixed gas, i.e., a measurement target gas by mixing a
dilution gas (i.e., air in this example) with the exhaust gas so as to render the

mixed gas to flow at a constant flow rate and to control an inflow rate of the dilution gas to thereby control an inflow rate of the exhaust gas, and further includes a collecting filter 2 which is provided on the measurement target gas flow passage (also, referred to as "mixed gas flow passage 12" hereinafter) through which the mixed gas flows so as to collect particulate matter (PM) contained in the mixed gas. Each part thereof is described below in detail. [0022]
The flow rate control mechanism 1 includes an exhaust gas flow passage 11 which is inserted to an exhaust pipe Ex of the internal combustion engine Eg so that a part of the exhaust gas flows therein, a dilution gas flow passage 14 through which the dilution gas flows, the mixed gas flow passage 12 which is commonly connected to the exhaust gas flow passage 11 and the dilution gas flow passage 14 so that the exhaust gas and the dilution gas are mixed, and a constant flow rate instrument 13 which is provided at an end portion of the mixed gas flow passage 12.
[23]
The mixed gas flow passage 12 includes a mixer 122 such as so-called a mini-tunnel or micro-tunnel in addition to a normal pipe 121. The constant flow rate instrument 13 includes a suction pump 131 such as e.g. a roots-blower and a critical orifice 132 connected to a downstream of the suction pump 131 so that the gas is passed therethrough at a constant flow rate. Herein, the flow rate determined by the constant flow rate instrument 13 is, e.g., 50 L/min.
[24]

A flow rate controller 15 such as a variable orifice is attached to a
start edge portion of the dilution gas flow passage 14 so as to adjust an inflow
rate of the dilution gas to the mixed gas flow passage 12, and a flow rate
meter (not shown) is also attached to the exhaust pipe Ex for measuring a
flow rate of the exhaust gas flowing through the exhaust pipe Ex.
[25]
In this configuration, the flow rate control mechanism 1 is controlled
by a command from an electronic control circuit such as a computer (not
shown) in order that, for example, a flow rate ratio between the flow rate of
the exhaust gas flowing through the exhaust pipe Ex and the flow rate of the
exhaust gas flowing through the measurement target gas flow passage is
made constant so as to control the inflow rate of the dilution gas to the mixed
gas flow passage 12.
[26]
The collecting filter 2 is provided downstream of the mixer 122 in the
mixed gas flow passage 12 so that the mixed gas flowing through the mixed
gas flow passage 12 at this installation portion are entirely passed through
so as to collect the particulate matter PM contained in the mixed gas. The
collecting filter 2 is known one and a detailed explanation of a material etc.
thereof is omitted here.
[0027]
Thus, a mass of the particulate matter PM contained in the exhaust
gas discharged from the internal combustion engine Eg can be calculated
based on the mass of the particulate matter PM collected by the collecting
filter 2. That is, as described above, since a ratio of the flow rate QTOTAL of

the exhaust gas flowing through the exhaust pipe Ex (i.e., the total flow rate
of the exhaust gas discharged from the internal combustion engine Eg) to a
flow rate QPART of the exhaust gas flowing through the measurement target
gas flow passage is kept constant, assuming that the ratio R= (JTOTAL / CJPART,
and the mass of the particulate matter PM collected by the collecting filter 2
is MTRAP, the mass HI-TOTAL of the particulate matter PM contained in the
exhaust gas discharged from the internal combustion engine Eg can be
represented as HI-TOTAL = R 'MTRAP. Hence, the mass of the particulate
matter PM contained in the exhaust gas can be calculated based on the mass
of the particulate matter PM collected by the collecting filter 2.
[0028]
In addition to the above configuration, in the present embodiment, a
gas analyzer 3 is further provided in order that a part of the mixed gas
flowing through the mixed gas flow passage 12 is shunted so as to measure
the particulate matter PM which is an object to be measured (referred to as
"measurement object" hereinafter) contained in the mixed gas.
[0029]
As shown in Figs. 1 and 2, the gas analyzer 3 includes a gas
introduction port PI which is connected to an end of a branch flow passage 4
branched from an upstream side of the collecting filter 2 in the mixed gas
flow passage 12, an object measurement device 35 which takes in a part of
the mixed gas introduced from the gas introduction port PI so as to count a
particle number of the particulate matter PM contained in the mixed gas, an
acquired gas flow rate measurement device 34 adapted to measure a flow
rate of the mixed gas acquired by the object measurement device 35, and a

gas supply device 36 adapted to supply another gas of a flow rate equal to the
gas flow rate measured by the acquired gas flow rate measurement device 34
back to the mixed gas flow passage 12.
[30]
An internal structure of the gas analyzer 3 is described in detail
referring to Fig. 2. After dusts contained in the mixed gas led to the gas
introduction port PI are removed by a dust removal device (such as, e.g., a
cyclone) 31, the mixed gas is shunted into a bypass flow passage 33 and a
sampling flow passage 32.
[31]
Most (about 95% to 99%) of the mixed gas flowing into the gas
introduction port PI is led to the bypass flow passage 33 and is derived as it
is to the outside from a first gas derivation port POl. The flow rate of the
mixed gas flowing through the bypass flow passage 33 is controlled to be
constant (e.g., 10 L/min in this example) by a constant flow rate instrument
such as a mass flow controller MFC4. Further, the first gas derivation port
POl is communicated with a portion between the constant flow rate
instrument 13 and the collecting filter 2 in the mixed gas flow passage 12
through a connecting passage 5. Thus, most of the mixed gas shunted from
the mixed gas flow passage 12 to the branch flow passage 4 and flowing into
the gas analyzer 3, that is, the mixed gas except the mixed gas introduced
into the sampling flow passage 32 is supplied again to the mixed gas flow
passage 12 through the bypass flow passage 33 and through the connecting
passage 5 and then flows into the constant flow rate instrument 13 of the
mixed gas flow passage 12, It is noted here that a symbol P provided on the

bypass flow passage 33 denotes a pump for forcibly leading the mixed gas to
flow toward the mixed gas flow passage 12.
[32]
The remaining mixed gas (in this case, 0.1 to 0.5 L/min, i.e., about 1%
to 5%) flowing into the sampling flow passage 32 is led to the object
measurement device 35 via the acquired gas flow rate measurement device
34.
[33]
The acquired gas flow rate measurement device 34 includes, e.g., a
fluid resistance (orifice, in this case) FO provided on the sampling flow
passage 32 and pressure gages P2 and P3 for measuring a pressure
difference before and after the fluid resistance FO and an absolute pressure
in the downstream side thereof. Thus, the flow rate of the gas flowing
through the sampling flow passage 32 can be calculated based on the
measurement pressures measured by the pressure gages P2 and.P3.
[34]
The object measurement device 35 is provided with a first dilution
mechanism 351, a shunt rate control mechanism 352, an evaporator unit EU
and a second dilution mechanism 353 in this order from the upstream and a
particle number counting mechanism CPC is arranged thereafter for
counting the particle number of the particulate matter PM.

The first dilution mechanism 351 includes a first dilution passage
351a which is connected to the sampling flow passage 32 to which the
dilution gas (i.e., air, in this case) is introduced and a first mixer PND1 which

is provided downstream of the connecting point thereof. A mass flow
controller MFC1 is provided on the first dilution passage 351a so that the
inflow rate of the dilution gas can be controlled.
[36]
The shunt rate control mechanism 352 is adapted to shunt a part of
the dilution mixed gas outputted from the first dilution mechanism 351 so as
to exhaust the same to the outside from the second gas derivation port P02
and lead the rest thereof to an evaporator unit EU. Specifically, the shunt
rate control mechanism 352 includes a first shunt passage 352a which is
branched from an output flow passage 351b of the first dilution mechanism
351, a constant flow rate instrument (i.e., a critical orifice, in this case)
provided on the first shunt passage 352a, a flow rate control gas introduction
passage 352b connected to an upstream side of the constant flow rate
instrument CF02 on the first shunt passage 352a, and a mass flow controller
MFC2 provided on the flow rate control gas introduction passage 352b.
Thus, the flow rate of the flow rate control gas (i.e., air, in this case) fed into
the first shunt passage 352a from the flow rate control gas introduction
passage 352b is controlled by the mass flow controller MFC2 so as to be able
to indirectly control the flow rate of the mixed gas flowing into the first shunt
passage 352a from output flow passage 351b of the first dilution mechanism
351.
The evaporator unit EU is a carburetor which is provided for the
purpose of removing volatile particles in this case.
[37]
The second dilution mechanism 353 is adapted to further dilute the

dilution mixed gas outputted from the evaporator unit EU and it includes a
second dilution passage 353a which is connected to an output passage EUa of
the evaporator unit EU so as to lead a dilution gas (i.e., air, in this case) to
flow therein and a second mixer PND2 provided downstream of the
connecting point thereof. A mass flow controller MFC3 is provided on the
second dilution passage 353 so as to control the inflow rate of the dilution
gas.
[38]
Apart of the mixed gas diluted through the first dilution mechanism
351 and the second dilution mechanism 353 etc. is led to a second shunt
passage 355a at a constant flow rate and is exhausted from a second gas
exhaust port P02 through a constant flow rate instrument CF03 (i.e., a
critical orifice, in this case), and the rest thereof is led to the particle number
counting mechanism CPC.
[39]
The particle number counting mechanism CPC is adapted to mix a
supersaturated organic gas such as, e.g., alcohol or butanol to be adhered to
the particulate matter contained in the exhaust gas so that the particulate
matter is grown to have a large diameter and the grown particulate matter
PM is exhausted from a slit and the number of the exhausted particles is
counted by applying laser beams. It is noted here that symbols T1 and T2
are thermometer, PI is a pressure gauge and BC is a buffer tank.
[40]
In this configuration, a dilution ratio indicating a degree of dilution
that the mixed gas introduced into the particle number counting mechanism

CPC is diluted from the pre-diluted mixed gas firstly flowing into the
sampling flow passage 32 can be calculated based on the introduction flow
rate of the pre-diluted mixed gas measured by the acquired gas flow rate
measurement device 34 and a flow rates of the respective mass flow
controllers MFC1 to MFC3, and the flow rate of the mixed gas introduced to
the particle number counting mechanism CPC can be calculated based on
the temperature and pressure measured by the thermometer T2 and the
pressure gauge PI which are provided upstream thereof. Therefore, the
particle number of the particulate matter PM contained in the pre-diluted
mixed gas first flowing into the sampling flow passage 32 can be calculated
based on these factors.
[41]
In the present embodiment, the flow rate of the pre-diluted mixed gas
first flowing into the sampling flow passage 32 can be also calculated by flow
rate controls executed by the respective mass flow controllers MFC1 to
MFC3.
[42]
In this configuration, the gas supply device 36 which is a specific
feature in configuration of the present embodiment is adapted to supply
another gas (i.e., air, in this case) of a flow rate equal to the flow rate of the
mixed gas acquired by the object measurement device 35 to the downstream
side of a shunt point in the mixed gas flow passage 12.
[43]
In specific, as shown in Fig. 2, the gas supply device 36 includes
another gas supply passage 36a for supplying another gas to the bypass flow

passage 33 and a flow rate control unit MFC5 (i.e., a mass flow controller, in
this case) which is provided on another gas supply passage 36a for
controlling a supply flow rate of another gas. Note that a symbol F in Fig. 2
denotes a filter.
[44]
Another gas supply passage 36a is connected to a portion between a
downstream of the constant flow rate instrument and an upstream of the
pump on the bypass flow passage 33 so that another gas supplied through
another gas supply passage 36a is joined with the mixed gas which is not
supplied to the object measurement device 35 of the mixed gas introduced
from the gas introduction port PI, i.e., the mixed gas flowing through the
bypass flow passage 33, and the resultant mixed gas flows into the constant
flow rate instrument 13 of the mixed gas flow passage 12 through the first
gas derivation port POl and through the connecting passage 5.

The flow rate of the mixed gas measured by the acquired gas flow
rate measurement device 34 is given to the flow rate control unit MFC5 as a
target value so that the air of the target flow rate is fed into the connecting
passage 5 through another gas supply passage 36a.
[46]
With this configuration, the gas of the flow rate equal to that of the
mixed gas shunted in the middle of the mixed gas flow passage 12, i.e., at an
upstream of the collecting filter 2 and fed to the gas analyzer 3 is supplied to
the downstream of the collecting filter 2 in the mixed gas flow passage 12 to
be led to flow into the constant flow rate instrument 13. Therefore, the total

flow rate of the exhaust gas which flows into the mixed gas flow passage 12
to serve as the mixed gas and the dilution gas can be precisely matched with
the gas flow rate derived from the mixed gas flow passage 12.
[47]
As a result, in this embodiment, it becomes possible to very
accurately control the inflow rate of the exhaust gas by the flow rate control
mechanism 1. Further, it becomes possible to accurately control a dilution
ratio of the exhaust gas and the dilution gas to be introduced to the mixer
122 and to accurately keep a ration of the flow rate of the exhaust gas
flowing through the exhaust pipe Ex and the flow rate of the exhaust gas
shunted from the exhaust pipe Ex, or as a result of this, it becomes possible
to very accurately measure the mass of the particulate matter PM collected
by the collecting filter 2. It is noted that the present invention is not limited
to the present embodiment as described above.
[48]
For example, as shown in Fig. 3, the mixed gas introduced into the
gas analyzer 3 may be entirely used as another gas (e.g., air) so as to be
supplied back to the mixed gas flow passage 12. In this case, the gas
analyzer 3 and the object measurement device 35 can be regarded as
synonymous with each other, and the acquired gas flow rate measurement
device 34 includes the mass flow controller MFC4 as an constituent element
thereof in addition to, e.g., the fluid resistance (i.e., orifice in this case) FO
and the pressure gauges P2 and P3. Moreover, in Fig. 3, by using, e.g.,
compressed air to be introduced as a heat gas, the pump P between the mass
flow controller MFC5 and the first gas introduction port POl can be omitted.

Moreover, the measurement target gas may be not only the mixed gas
of the exhaust gas and the dilution gas but also the exhaust gas per se which
is not diluted. This aspect is considered to be preferred in a
vehicle-mounted type a gas analyzer and the like. Further, as the
measurement target gas, it may be possible to apply not only the exhaust gas
of the internal combustion engine but also various gases such as gases
introduced to and derived from a combustion engine such as a boiler or a
chemical reaction furnace.
[50]
In addition, the dilution gas is not only air but also such as, e.g., an
inert gas may be used. In short, in the present invention, various gases
including the mixed gas of the measurement target gas added with the other
gas are regarded as another gas if not the measurement target gas per se,
regardless of the kinds of the gases.
Moreover, the gas analyzer is not limited to those counting the
particulate matter, and the present invention can be applied to various types
of analyzers.
In addition, the present invention is not limited to the above
embodiments, and it is needless to say that various changes and
modifications can be made within the scope of the present invention unless
departing from the spirit thereof.
Industrial Applicability
[51]
According to the present invention, even though the object

measurement device is adapted to dilute and absorb the acquired
measurement target gas, since another gas having a flow rate equal to the
acquired flow rate is supplied to the measurement target gas flow passage,
the flow rate introduced into the measurement target gas flow passage and
the flow rate derived therefrom are matched so as to ensure high accuracy of
controlling the flow rate of the gas introduced into the measurement target
gas flow passage and derived therefrom as well as measurement accuracy of
the measurement object.
^ Reference Signs List
[0052]
100 ... Gas analyzing system
PI ... Gas introduction port
3 ... Gas analyzer
34 ... Acquired gas flow rate measurement device
35 ... Object measurement device
36 ... Gas supply device

CLAIMS:
1. A gas analyzer comprising:
a gas introduction port communicating with a shunt point provided
in a measurement target gas flow passage so that a part of the measurement
target gas flowing through the measurement target gas flow passage is
introduced.'
an object measurement device adapted to acquire the measurement
target gas introduced from the gas introduction port so as to measure a
quantity or concentration of a measurement object contained in the
measurement target gas)
an acquired gas flow rate measurement device adapted to measure a
flow rate of the measurement target gas acquired by the object measurement
device.' and
a gas supply device adapted to supply another gas of a flow rate equal
to the gas flow rate measured by the acquired gas flow rate measurement
device to a downstream side of the shunt point in the measurement target
gas flow passage.
2. The gas analyzer according to claim 1, wherein the object
measurement device is adapted to acquire a part of the measurement target
gas introduced from the gas introduction port, and
wherein the gas supply device is adapted to add another gas to the
rest of the measurement target gas introduced from the gas introduction port
so as to supply the resultant gas to the downstream side of the shunt point in

the measurement target gas flow passage.
3. A gas analyzing system comprising:
a measurement target gas flow passage in which a measurement
target gas flows;
a constant flow rate instrument provided on the measurement target
gas flow passage in order to keep a constant flow rate of the measurement
target gas flowing through the measurement target gas flow passage so that
the constant flow rate of the measurement target gas is passed;
a branched flow passage branched from a shunt point provided in an
upstream side of the constant flow rate instrument in the measurement
target gas flow passage;
a gas introduction port connected to the branched flow passage so
that a part of the measurement target gas is introduced;
an object measurement device adapted to acquire the measurement
target gas introduced from the gas introduction port so as to measure a
quantity or concentration of a measurement object contained in the
measurement target gas."
an acquired gas flow rate measurement device adapted to measure a
flow rate of the measurement target gas acquired by the object measurement
device; and
a gas supply device adapted to supply another gas of a flow rate equal
to the gas flow rate measured by the acquired gas flow rate measurement
device to a portion between a downstream side of the shunt point and an
upstream side of the constant flow rate instrument in the measurement

target gas flow passage.
4. A gas analyzing system comprising:
an exhaust gas flow passage into which a part of an exhaust gas
exhausted from an internal combustion engine is introduced;
a dilution gas flow passage into which a dilution gas is introduced in
order to dilute the exhaust gas;
a measurement target gas flow passage in which the exhaust gas
flowing into the exhaust gas flow passage and the dilution gas flowing into
the dilution gas flow passage are joined together and a resultant mixed gas
thereof serving as a measurement target gas flows therein;
a constant flow rate instrument provided on the measurement target
gas flow passage in order to keep a constant flow rate of the measurement
target gas flowing through the measurement target gas flow passage so that
the constant flow rate of the measurement target gas is passed;
a branched flow passage branched from a shunt point provided in an
upstream side of the constant flow rate instrument in the measurement
^ target gas flow passage!
a gas introduction port connected to the branched flow passage so
that a part of the measurement target gas is introduced;
an object measurement device adapted to acquire the measurement
target gas introduced from the gas introduction port so as to measure a
quantity or concentration of a measurement object contained in the
measurement target gas;
an acquired gas flow rate measurement device adapted to measure a

flow rate of the measurement target gas acquired by the object measurement
device»' and
a gas supply device adapted to supply another gas of a flow rate equal
to the gas flow rate measured by the acquired gas flow rate measurement
device to a portion between a downstream side of the shunt point and an
upstream side of the constant flow rate instrument in the measurement
target gas flow passage.
5. The gas analyzing system according to claim 4 further comprising:
a flow rate control device adapted to control an inflow rate of the
exhaust gas by controlling an inflow rate of the dilution gas so as to keep a
flow rate ratio to be constant between the flow rate of the exhaust gas
exhausted from the internal combustion engine and the exhaust gas flowing
into the exhaust gas flow passage," and
a collecting filter for passing through the measurement target gas
flowing in a downstream side of the branched point of the measurement
target gas flow passage and collecting particulate matter contained in the
measurement target gas,
wherein a mass of the particulate matter contained in the exhaust
gas exhausted from the internal combustion engine can be calculated based
on the mass of the particulate matter collected by the collecting filter and the
flow rate ratio.
6. The gas analyzing system according to claim 4, wherein the object
measurement device comprises a dilution mechanism for diluting the

acquired measurement target gas and a particle number counting mechanism for counting the number of particles of the particulate matter contained in the measurement target gas diluted by the dilution mechanism.