The present invention relates to an installation for following up the evolution of the
quality of a lubricant circulating in a piece of equipment, such as a ship engine. The
invention also relates to a method for following up the evolution of the dissolved iron
5 content of a lubricant.
In the field of internal combustion engines used on merchant vessels, it is known
that the situation of an engine should be monitored by analyzing a lubricant circulating in
this engine. Such an analysis gives the possibility of detecting wear or corrosion
phenomena which tend to occur in an engine. In the past, the operation of the engines
10 was relatively stabilized and it was sufficient to control the quality of a lubricant in an oneoff
way, during calls for anticipating the maintenance operations to be carried out.
Nowadays, the engines are increasingly elaborated and sensitive to wear and corrosion
phenomena, so that analyses have to be conducted at sea, notably for tracking the Base
Number or BN of the engine oil or its iron particle content resulting from abrasion
15 phenomena. This imposes training of the personnel and loading on board elaborated
equipment, the operation of which is relatively difficult to control, even by a trained
seaman. Further, this increases the workload of the personnel.
Within this framework, providing a system for analyzing the TBN (Total Base
Number) is known from the article « A low cost mid-infrared sensor for on line
20 contamination monitoring of lubricating oils in marine engines » of Ben Mohammadi et al.
(Optical Sensing and Detection Conference – Brussels - 12-15.4.2010), which
corresponds to the total basicity number, by means of a sensor in which a sample of the
lubricant to be investigated is positioned. The piece of equipment used is elaborated and
its handling is complex. If such a piece of equipment were to be loaded onboard a ship, its
25 application would require regular sampling on the engine of the ship of an amount of oil
intended to form a measurement sample. This would be both long and complex.
WO-A-03/073075 discloses a method for analyzing the basicity of a lubricant
during which a measurement, carried out on a sample of a lubricant to be controlled, is
compared with measurements carried out on samples of a reference lubricant. There
30 again, this approach is provided for operation in a laboratory and requires a qualified
workforce.
WO-A-2010/046591 provides the use of a system loaded on board in which the oil
flowing out from an engine is directed towards a functional component associated with a
measurement system giving the possibility of determining its basicity number or its metal
35 particle content. In practice, the oil flow rate leaving the engine is low and the flow at the
2
outlet of the engine consists of droplets which trickle inside a duct, to the point that it is not
certain that the functional component be supplied with sufficient oil flow rate so that the
measurements which it carries out are correct.
These known methods and equipment do not give the possibility of taking into
account the dissolved iron content of the lubricant, 5 while this content is significant for
certain phenomena which occur inside the engine, and more particularly of the corrosion
phenomenon of the liners of an engine, this phenomenon being related to the
condensation of mineral acids, such as sulfuric acid resulting from the combustion of
sulfur-containing fuels, or further of organic acids resulting from the combustion and the
10 degradation of the actual lubricant. This dissolved iron content is also representative of
the quality of the oil, i.e. of its physical and/or chemical properties.
On the other hand, laboratory equipment which may give the possibility of
detecting the dissolved iron content of a lubricant is difficult to transport and of a complex
use, which makes them not very accessible to a seaman, even trained for this.
15 These problems are not only posed on two-stroke or four-stroke engines for
propelling ships but also on other secondary engines also loaded onboard ships, for
example for accessories of the hoist type. Generally, monitoring the dissolved iron content
of a lubricant is important for all lubricated engines and known techniques are not very
suitable for automation.
20 These are the drawbacks which the invention more particularly means to remedy
by proposing a novel installation for following up the evolution of the quality of a lubricant
circulating in a piece of equipment which is adapted for operating in a simple and
autonomous way, which notably discharges the onboard personnel of a ship from
repeated and elaborated tasks.
25 For this purpose, the invention relates to an installation for following up the
evolution of the quality of a lubricant circulating in a piece of equipment, this installation
comprising at least one conduit for circulating the lubricant, this conduit being connected,
upstream to the piece of equipment and, downstream to a recovery pan. According to the
invention, this installation comprises a first controlled valve for interrupting the circulation
30 of a lubricant in the conduit, a buffer tank for accumulating lubricant, a first bypass line, a
second line for discharging the lubricant, from the buffer tank to the recovery pan, as well
as a third controlled valve for interrupting the circulation of the lubricant in the second
discharge line and a sensor for determining the dissolved iron content of an amount of
lubricant contained in the buffer tank.
3
By means of the invention, the buffer tank is used for accumulating an amount of
lubricant sufficient for allowing the dissolved iron sensor to carry out a suitable
measurement, without requiring any complex handling.
The lubricant which is relevant in the present invention comprises at least one
lubricating base oil. Generally, the lubricating 5 base oils may be oils of mineral, synthetic or
vegetable origin as well as mixtures thereof. The mineral or synthetic oils generally used
belong to one of the groups I to V according to the classes defined in the API classification
(or their equivalents according to the ATIEL classification) as summarized below. The API
classification is defined in American Petroleum Institute 1509 "Engine oil Licensing and
10 Certification System" 17th edition, September 2012. The ATIEL classification is defined in
"The ATIEL Code of Practice", number 18, November 2012.
Content of
saturated
substances
Sulfur
content Viscosity index
Group I mineral oils < 90 % > 0.03 % 80 􀁤 VI < 120
Group II hydrocracked oils 􀁴 90 % 􀁤 0.03 % 80 􀁤 VI < 120
Group III
hydrocracked or hydro-isomerized
oils
􀁴 90 % 􀁤 0.03 % 􀁴 120
Group IV PAO (Poly alpha olefins)
Group V Esters and other bases not included in the bases of
group I to IV
The mineral oils of Group I may be obtained by distillation of selected naphthenic
or paraffinic crude oils and then by purification of the distillates obtained by methods such
as extraction with a solvent, de-waxing with a solvent or catalytic de-waxing,
15 hydrotreatment or hydrogenation. The oils of Groups II and III are obtained by more
elaborate purification methods, for example by a combination of treatment selected from
hydrotreatment, hydrocracking, hydrogenation and catalytic de-waxing. Examples of
synthetic base oils of Group IV and V include polyisobutenes, alkylbenzenes and
poly-alpha-olefins such as polybutenes or further esters.
20 In lubricants, the lubricating base oils may be used alone or as a mixture. For
example, mineral oil may be combined with synthetic oil.
The cylinder oils for two-stroke marine engines are generally characterized by a
viscosimetric grade SAE-40 to SAE-60, generally SAE-50 equivalent to a kinematic
viscosity at 100°C comprised between 16.3 and 21.9 mm²/s measured according to the
25 ASTM D445 standard. The oils of grade SAE-40 have a kinematic viscosity of 100°C
comprised between 12.5 and 16.3 cSt measured according to the ASTM D445 standard.
The oils of grade SAE-50 have a kinematic viscosity at 100°C comprised between 16.3
and 21.9 cSt measured according to the ASTM D445 standard. The oils of grade SAE-60
4
have a kinematic viscosity at 100°C comprised between 21.9 and 26.1 cSt measured
according to the ASTM D445 standard. The lubricants used with the invention preferably
have a kinematic viscosity measured according to the ASTM D445 standard at 100°C
ranging from 12.5 to 26.1 cSt, preferentially from 16.3 to 21.9 cSt. In order to obtain such
a viscosity, these lubricants may further comp 5 rise one or several additives. Typically, a
conventional formulation of a lubricant for marine engines, for example two-stroke
engines, is of grade SAE-40 to SAE-60, preferentially SAE-50 (according to the SAE J300
classification) and comprises at least 40 % by weight of a lubricant base oil of mineral,
synthetic origins or mixtures thereof, adapted to the use for a marine engine. For example,
10 a lubricating base oil of group I, according to the API classification, may be used for
formulating a cylinder lubricant. The lubricating base oils of group I have a Viscosity Index
(VI) ranging from 80 to 120; their sulfur content is greater than 0.03% and their content of
saturated hydrocarbon compounds is less than 90%.
The lubricant may further comprise an additive selected from overbased
15 detergents or neutral detergents. The detergents are typically anionic compounds
including a long lipophilic hydrocarbon chain and a hydrophilic head, the associated cation
is typically a metal cation of an alkaline or earth-alkaline metal. The detergents are
preferentially selected from salts of alkaline or earth-alkaline metals (notably preferentially
calcium, magnesium, sodium or barium) of carboxylic acids, sulfonates, salicylates,
20 naphthenates, as well as phenate salts. These metal salts may contain the metal in an
approximately stoichiometric amount relatively to the anionic group(s) of the detergent. In
this case, these are referred to as non-overbased or « neutral » detergents, although they
also provide some basicity. These « neutral » detergents typically have a BN, measured
according to ASTM D2896, of less than 150 mg KOH/g, or less than 100 mg KOH/g, or
25 further less than 80 mg KOH/g of detergent. This type of so-called neutral detergents may
contribute for one part to the BN of the lubricants. Neutral detergents of the type:
carboxylates, sulfonates, salicylates, phenates, naphthenates of alkaline and earth
alkaline metals, for example calcium, sodium, magnesium, barium, are for example used.
When the metal is in excess (in an amount greater than the stoichiometric amount
30 relatively to the anionic group(s) of the detergent), one is dealing with so-called overbased
detergents. Their BN is high, greater than 150 mg KOH/g of detergent, typically ranging
from 200 to 700 mg KOH/g of detergent, preferentially from 250 to 450 mg KOH/g of
detergent. The excess metal providing the overbased nature to the detergent appears as
metal salts insoluble in oil, for example a carbonate, hydroxide, oxalate, acetate,
35 glutamate, preferentially carbonate. In a same overbased detergent, the metals of these
5
insoluble salts may be the same as those of the detergents which are soluble in oil or else
may be different. They are preferentially selected from calcium, magnesium, sodium or
barium. The overbased detergents thus appear as micelles consisting of insoluble metal
salts maintained in suspension in the lubricant by the detergents as metal salts soluble in
oil. These micelles may contain one or several types of 5 insoluble metal salts, stabilized
with one or several types of detergent. The overbased detergents including a single type
of metal salt soluble in the detergent will generally be designated according to the nature
of the hydrophobic chain of this latter detergent. Thus, they will be said to be of the
phenate, salicylate, sulfonate, naphthenate type depending on whether this detergent is a
10 phenate, salicylate, sulfonate, or naphthenate respectively. The overbased detergents will
be said to be of the mixed type if the micelles comprise several types of detergents,
different from each other by the nature of their hydrophobic chain. The overbased
detergent and the neutral detergent may be selected from carboxylates, sulfonates,
salicylates, naphthenates, phenates, and the mixed detergents associating at least two of
15 these types of detergents. The overbased detergent and the neutral detergent are notably
compounds based on metals selected from calcium, magnesium, sodium or barium,
preferentially calcium or magnesium. The overbased detergent may be overbased with
insoluble metal salts selected from the group of alkaline metal and earth alkaline metal
carbonates, preferentially calcium carbonate. The lubricant may comprise at least one
20 overbased detergent and at least one neutral detergent as defined above.
As mentioned above, in an embodiment of the invention, the lubricant may have a
BN determined according to the ASTM D–2896 standard of at most 50, preferably of at
most 40, advantageously of at most 30 milligrams of potash per gram of lubricant, notably
ranging from 10 to 30, preferably from 15 to 30, advantageously from 15 to 25 milligrams
25 of potash per gram of lubricant. In this embodiment of the invention, the lubricant may not
comprise overbased detergents based on alkaline or earth-alkaline metals with metal
carbonate salts.
In another embodiment of the invention, the lubricant has a BN determined
according to the ASTM D-2896 standard of at least 50, preferentially of at least 60, more
30 preferentially of at least 70, advantageously from 70 to 100.
The lubricant may also comprise at least one additional additive selected from
dispersants, anti-wear additives or any other functional additive. The dispersants are well
known additives used in the formulation of a lubricant, notably for application in the marine
field. Their primary role is to maintain in suspension the initially present particles or
35 appearing in the lubricant during its use in the engine. They prevent their agglomeration
6
by acting on the steric hindrance. They may also have a synergistic effect on
neutralization. The dispersants used as additives for a lubricant typically contain a polar
group, associated with a relatively long hydrocarbon chain, generally containing from 50 to
400 carbon atoms. The polar group typically contains at least one nitrogen, oxygen or
phosphorus element. 5 The compounds derived from succinic acid are dispersants which
are particularly used as lubrication additives. In particular succinimides are used, obtained
by condensation of succinic anhydrides and of amines, succinic esters obtained by
condensation of succinic anhydrides and of alcohols or polyols. These compounds may
then be treated with various compounds notably sulfur, oxygen, formaldehyde, carboxylic
10 acids and compounds containing boron or zinc in order to produce, for example,
succinimide borates or succinimides blocked with zinc. Mannich bases, obtained by
polycondensation of phenols substituted with alkyl groups, of formaldehyde and of primary
or secondary amines, are also compounds used as dispersants in lubricants. In an
embodiment of the invention, the dispersant content may be greater than or equal to 0.1%,
15 preferably from 0.5 to 2%, advantageously from 1 to 1.5% by weight based on the total
weight of the lubricant. The anti-wear additives protect the surfaces subject to friction by
forming a protective film adsorbed on these surfaces. The most currently used is zinc
di-thiophosphate or DTPZn. In this category, various phosphorus-containing, sulfurcontaining,
nitrogen-containing, chlorine-containing and boron-containing compounds are
20 also found. There exists a large variety of anti-wear additives, but the most used category
is that of phosphorus-sulfur-containing additives such as metal alkylthiophosphates, in
particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or
DTPZn. The preferred compounds are of formula Zn((SP(S)(OR1)(OR2))2, wherein R1 and
R2 are alkyl groups, preferentially including from 1 to 18 carbon atoms. The DTPZn is
25 typically present at contents of the order of 0.1 to 2% by weight based on the total weight
of the lubricant. Amine phosphates, polysulfides, notably sulfur-containing olefins, are also
commonly used anti-wear additives. In lubricants for marine engines are also encountered
anti-wear and extreme pressure additives of the nitrogen-containing and sulfur-containing
type, such as for example metal dithiocarbamates, in particular molybdenum
30 dithiocarbamate. The esters of glycerol are also anti-wear additives. Mention may for
example be made of mono-, di- and tri-oleates, monopalmitates and monomyristates. In
an embodiment, the anti-wear additive content ranges from 0.01 to 6 %, preferentially
from 0.1 to 4 % by weight based on the total weight of the lubricant.
The other functional additives may be selected from thickeners, anti-foam additives
35 for going against the effect of the detergents, which may for example be polar polymers
7
such as polymethylsiloxanes, polyacrylates, anti-oxidant and/or anti-rust additives, for
example organo-metal detergents or thiadiazoles. The latter are known to one skilled in
the art. These additives are generally present at a weight content from 0.1 to 5% based on
the total weight of the lubricant.
According to advantageous but non 5 -mandatory aspects, an installation according
to the invention may incorporate one or several of the following features, taken in any
technically admissible combination:
- The sensor operates according to laser-induced breakdown spectroscopy or
LIBS technology. In this case, the sensor advantageously comprises an emitter capable of
10 emitting a laser beam towards an interface between the amount of lubricant contained in
the buffer tank and an amount of air contained in the buffer tank, as well as a receiver
intended to receive a beam emitted in return, from the interface.
- The sensor is installed in the upper portion of the buffer tank.
- The installation comprises at least one other sensor positioned on the second
15 discharge line and capable of determining a physico-chemical parameter of the amount of
lubricant contained in the buffer tank.
- The second sensor is selected from a density, viscosity, humidity and
temperature sensor and a basicity index sensor.
- The installation comprises means for gas pressurization of the inner volume of
20 the buffer tank, notably a source of compressed air and a set of valves or a pneumatic
distributor for selectively having the inner volume of the buffer tank communicate with the
compressed air source or with the ambient atmosphere.
- The installation comprises means for detecting the lubricant level in the buffer
tank, notably a gas pressure sensor in the inner volume of the buffer tank.
25 Moreover, the invention relates to an automated method for following up the
evolution of the dissolved iron content of a lubricant circulating in a piece of equipment, by
means of an installation as mentioned above. This method comprises steps:
a) closing the first valve
b) opening the second valve and closing the third valve for supplying the buffer
30 tank from an amount of lubricant accumulated in the conduit upstream from
the first valve
c) using the sensor for determining the dissolved iron content of the amount of
lubricant contained in the buffer tank.
Advantageously, when the installation comprises at least one other sensor
35 positioned on the second discharge line and capable of determining a physical or
8
chemical parameter of the amount of lubricant contained in the buffer tank, it comprises
an additional step d), posterior to steps a) and c) and consisting of:
d) opening the third valve for having the lubricant present in the buffer tank
circulate through the second discharge line, in contact with the second sensor.
The invention also relates to a method 5 for following up the operation of a piece of
equipment loaded on board a ship, this method comprising the determination, onboard the
ship, of the dissolved iron content of a lubricant of the relevant piece of equipment by
applying an automated method as mentioned above.
The invention will be better understood and other advantages thereof will become
10 more clearly apparent in the light of the description which follows of two embodiments of
an installation according to its principle, only given as an example and made with
reference to the appended drawings wherein:
- Fig. 1 is a schematic illustration of the principle of an installation according to the
invention as loaded onboard a ship,
15 - Fig. 2 is a schematic illustration at a smaller scale of the fluid portion of the
installation of Fig. 1 in a first configuration of use,
- Figs. 3 to 5 are views similar to Fig. 2 when the installation is in a second, third
and fourth configuration of use,
- Fig. 6 is a view similar to Fig. 1 for an installation according to a second
20 embodiment of the invention,
- Figs. 7 to 11 and 13 to 18 are views similar to Fig. 2 for the installation of Fig. 6 in
different configurations of use,
- Fig. 12 is a view at a larger scale of the detail XII in Fig. 11, and
- Fig. 19 is a view similar to Fig. 1 for an installation according to a third
25 embodiment of the invention.
In Figs. 2 to 5 and 7 to 18, the lubricant present or circulating in a portion of the
installation is illustrated in gray color.
The installation 2 illustrated in figs. 1 to 5 is loaded onboard a ship illustrated in
Fig. 1 by its engine M which includes several cylinders, for example twelve or fourteen
30 cylinders. A conduit 4 connects the engine M to a pan 6 for recovering lubricant. In
practice, the engine oil flows by gravity into the conduit 4 with a pressure P4 comprised
between 1.1 and 6 bars absolute. The oil flow rate in the conduit 4 may be low, to the
point that the oil trickles on the internal wall of this conduit.
9
This conduit 4 extends vertically, from top to bottom, from the engine M towards
the pan 6. In this embodiment, the oil flowing in the conduit 4 stems from at least one
cylinder of the engine M.
A capping orifice 8 is provided on the conduit 4 and equipped with a manually
controlled valve 10, which gives the possibility 5 of sampling an amount of oil flowing out of
the engine M in order to proceed with physico-chemical analyses, according to an
approach known per se.
The installation 2 comprises a stop valve 20 mounted on the conduit 4 and which
gives the possibility of selectively interrupting the flow of oil into the conduit 4, towards the
10 pan 6. The stop valve 20 is controlled by an electronic unit 22 by means of an electrical
signal S20.
As exclusively visible in Fig. 1, the installation 2 comprises a casing 24, illustrated
by its axis line mark and inside which are positioned the constitutive elements of the
installation 2, except for the portion of the stop valve 20 which is integrated to the conduit
15 4.
The installation 2 also comprises a buffer tank 26 which is positioned in the casing
24 and which is connected to the conduit 4 by means of a first bypass line 28.
The mouth of the line 28 is noted as 282. This mouth is positioned upstream from
the valve 20 on the conduit 4. The first bypass line 28 is equipped, from its mouth 282 to
20 its opening mouth 284 in the buffer tank 26, with a filter 30, with a stop valve 32 and a
tapping orifice 34. The filter 30 is used for preventing impurities with a too large size of
flowing into the first bypass line 28. The stop valve 32 gives the possibility optionally of
clearing or closing the first bypass line 28. The valve 32 is controlled by the electronic unit
22, by means of an electric signal S32. The tapping orifice 34 is connected, through a
25 controlled valve 36, to a pressurized air source 12 which is not part of the installation 2 but
which belongs to the standard equipment of a ship.
In practice, the pressurized air source 12 may be a compressor onboard the ship
and which supplies a compressed air network which is also used at equipment other than
the installation 2. Alternatively, the source 12 may be a pump dedicated to the installation
30 2.
The installation 2 also comprises a tapping orifice 38 connected to the tank 26, on
which is mounted a stop valve 40 and which gives the possibility of putting the inner
volume V26 of the tank 26 in communication with the ambient atmosphere.
In this embodiment, the tapping orifices 34 and 38 are independent. Alternatively,
35 they may be replaced by a single tapping orifice, connected to the first line 28 or directly to
10
the tank 26, on which the valves 36 and 40 are mounted in parallel, while being
respectively connected to the pressurized air source 12 and the ambient atmosphere. In
this case, it is possible to combine the valves 36 and 40 as a single three-way valve.
The valves 36 and 40 are controlled by the electronic unit 22 by means of
5 respective electric signals S36 and S40.
The installation 2 also comprises a second line 42 for discharging the lubricant,
from the inner volume V26 of the tank 26 to the recovery pan 6. The second discharge
line 42 is therefore positioned downstream from the first bypass line 28 and from the tank
26, on the flow path of the lubricant. In the example, the second line 42 extends from the
10 tank 26 to the conduit 4. Its mouth 422 is located in the low portion of the tank 26, while its
outflow mouth 424 is positioned on the conduit 4, downstream from the stop valve 20, as
illustrated in the figures, which gives the possibility of reducing the period of an analysis
cycle since the stop valve 20 may be closed in order to generate an oil column in the
conduit 4, while measuring steps take place. Alternatively, the outflow mouth 424 of the
15 second line 42 is positioned upstream from the stop valve 20, which gives the possibility
of carrying out simultaneously steps for emptying and for unblocking the filter 30 and
optionally reducing the cost of the installation 2.
The second line 42 is equipped with a stop valve 44 which is controlled by the
electronic unit 22 by means of an electric signal S44.
20 Two sensors 46 and 48 are positioned on the line 42, upstream from the valve 44.
The sensor 46 gives the possibility of measuring the density D, viscosity V, the
humidity H and the temperature T of a liquid present or flowing in the second line 42. This
sensor may be of the type of the one marketed by an AVENISENSE under the name of
Cactus. Alternatively, the sensor 46 may be of another type or only allow measurement of
25 a single one or some of the parameters mentioned above.
The sensor 48 is a basicity index sensor or BN, sometimes called an alkalinity
index. This may be a sensor operating with infrared technology, in the medium infrared, or
any other sensor adapted to the determination of the BN of a lubricant.
The installation 2 also comprises a third sensor 50 mounted in the upper part of
30 the tank 26 and positioned for aiming an interface I26 defined between an amount of
lubricant present in the tank 26 and the air present above this amount. The sensor 50 is a
sensor using Laser-Induced Breakdown Spectroscopy (LIBS) technology. This may also
be a sensor operating according to another technology.
This sensor comprises an emitter of a laser beam towards the interface I26 and a
35 receiver giving the possibility of receiving a laser beam reflected on the interface I26. In
11
particular, the structure of the sensor 50 may be identical or similar to the one illustrated in
Fig. 12 for the second embodiment, except for the fact that the outflow mouth 284 of the
first line 28 crosses the upper wall of the tank 26 in this first embodiment.
The installation 2 also comprises a first level sensor 54 and a second level sensor
56 which respectively give the possibility of detecting 5 when the amount of oil in the tank
26 attains a first level N1 or a second level N2. The output electric signals S54 and S56
from the sensors 54 and 56 are delivered to the unit 22.
Alternatively, the sensors 54 and 56 may be replaced with a single sensor, such as
a pressure sensor, which gives the possibility of detecting when the oil attains each of the
10 two levels N1 and N2 in the tank 26.
Figs. 2 to 5 schematically illustrate the successive steps of an automated method
applied by means of the installation 2 of Fig. 1. This method is automated in the sense
that it may be implemented, partly or preferably totally, without any human intervention,
under the control of the unit 22. The same applies for the method explained hereafter
15 concerning the second embodiment of the invention.
By default, and outside the sampling phases, the oil leaving the engine flows into
the conduit 4, in the direction of the arrow F1 in Fig. 1, from the engine M to the recovery
pan 6, without being retained by the valve 20 which is in an open or through-configuration,
while the other valves are closed.
20 When the basicity index (or base number) of the oil leaving the engine M should be
determined, the unit 22 drives the valve 20 to closure, so that a reservoir is generated in
the conduit 4 where an oil amount accumulates, i.e. lubricant, as illustrated by the shaded
portion L in Fig. 2.
In the configuration of Fig. 2, the conduit 4 is used as a decantation column and
25 impurities I accumulate in the vicinity of the valve 20, inside the conduit 4 and in the lower
portion of the lubricant amount L.
In this first step illustrated by the configuration of Fig. 2, the valves 32 and 40 are
open while the valves 36 and 44 are closed.
When the lubricant level L in the conduit or column 4 attains the mouth 282, oil
30 begins to flow through the first bypass line 28, more particularly through the filter 30 and
the valve 32, as far as into the inner volume V26 of the tank 26 in which the oil flows by
gravity. Indeed, the outflow mouth 284 of the first line 28 is located in the upper portion of
the tank 26 and the oil may flow along the wall of the tank 26. As the valve 44 is closed,
the oil gradually fills up the portion of the second discharge line 42 located upstream from
35 the valve 44, including the internal volumes of the sensors 46 and 48, and then the inner
12
volume V26 by driving out the air towards the atmosphere, through the valve 40. This step
corresponds to the configuration illustrated in Fig. 3.
When the sensor 56 detects that the oil level N2 inside the tank 26 is attained, the
unit 22 causes the installation 2 to switch to a new step, in which the sensor 50 is
activated for determining 5 the dissolved iron content, in particular of the Fe2+ and Fe3+ ions,
of the lubricant amount L1 then contained in the tank 26. The position of the interface I26
is known since it is located at the level N2. Thus the measurement carried out by means
of the sensor 50 is reliable and its output signal S50, which is transmitted to the unit 22,
may be integrated to the output signal S2 of the installation 2.
10 During this step illustrated by the configuration of Fig. 4, the valve 20 passes into
the open configuration, which allows emptying of the decantation column by directing the
remainder of the lubricant amount L present upstream from the valve 20 as well as the
impurities I towards the recovery pan 6. The flow in the direction of the arrow F1 therefore
continues as far as into the pan 6. Moreover, the valves 32 and 40 are closed and the
15 valve 36 is open, which gives the possibility of putting the portion of the volume V26 which
is not occupied by the lubricant, i.e. the portion of this volume V26 located above the level
N2, under an air pressure P1 equal to that of the air source 12, which, in the example has
the value of 7 bars absolute.
This having been done, the unit 22 causes the installation 2 to switch to a next
20 step, illustrated by the configuration of Fig. 5, when the valve 44 is open, the other valves
retaining their configuration state of Fig. 4. In this case, the pressure of the air P1 in upper
portion of the volume V26 has the effect of pushing the oil into the second discharge line
42, through the sensors 46 and 48, which gives the possibility to these sensors of
providing the unit 22 with signals S46, respectively S48, representative of the parameters
25 which they have detected.
If required, the signals S46 and S48 may be processed in the unit 22 in order to
determine the values of the control parameters, notably by comparison with known values
for reference lubricants.
The signals S46 and S48, or extrapolated signals from these signals, may be
30 provided to the outside of the installation 2 as a conjugate signal S2 which also includes
the signal S50, which may be used by a central processing unit for controlling the engine
M.
In practice, the passage section of the basicity index sensor 48 is of about 3 mm x
0.1 mm and this passage section should be able to be supplied with a sufficient flow, for a
35 sufficient time for carrying out the measurement of the basicity index. The construction of
13
the installation with the tank 26 gives the possibility of generating a reserve forming an oil
« buffer », as the amount of oil L1 contained in the tank 26 in the configuration of Fig. 4. A
portion of this oil reserve L1 may be poured, either continuously or sequentially, into the
second discharge line 42 so that the sensor 48 has a sufficient amount of oil to be
5 analyzed.
From the configuration of Fig. 5, it is possible, in a subsequent step to continue
emptying of the tank 26 and of the whole of the second discharge line 42 by maintaining
the valve 44 open and by continuing the injection of compressed air through the valve 36.
Alternatively, it is possible to stop the emptying of the tank 26 when the oil level
10 attains the level N1, so as to permanently retain an amount of oil L2 in the second
discharge line 42, in particular in the sensors 46 and 48, for which the active portions in
contact with the oil do not risk drying. If this second approach is selected, a certain
amount of oil has to be used during a next measurement, for cleaning beforehand the
second discharge line 42 and for not perturbing the next measurement.
15 In the second and third embodiments of the invention illustrated in Fig. 6 and the
following, the elements similar to those of the first embodiment bear the same references.
In the following, what distinguishes these embodiments from the previous one is mainly
described.
In the embodiment of figs. 6 to 18, the first and second lines for 28 and 42 join up
20 at a T-shaped junction 29. Thus, the outflow mouth 284 of the first bypass line 28
coincides with the mouth 422 of the second discharge line 42. The line segment located
between the tank 26 and the junction 29 is common to the first and second lines 28 and
42. This line segment opens in the low portion of the tank 26, so that the oil which flows
from the conduit 4 to the tank 26 directly arrives into the low portion of this tank.
25 Three levels N1, N2 and N3 are defined in the tank 26, the N1 and N2 levels being
comparable with those of the first embodiment.
In this second embodiment, no level sensors identical with the level sensors 54
and 56 are used, but a pressure sensor 58, the output signal S58 of which is provided to
the electronic control unit 22. Moreover, a level sensor 60 is mounted in the conduit 4,
30 upstream from the valve 20, i.e. above the latter.
Further, the tapping orifices 34 and 38 and the valves 36 and 40 of the first
embodiment are replaced by a single tapping orifice 38’ on which is connected the
pressure sensor 58, as well as a three-way and three-orifice distributor 62 which is
connected to the pressurized air source 12 on the one hand and to the ambient
14
atmosphere on the other hand. The distributor 62 is controlled by the unit 22 by means of
a dedicated electric signal S62.
The installation 2 comprises, like in the first embodiment, a third sensor 50 for
determining the dissolved iron content, mounted in the upper portion of the tank 26 and
positioned f 5 or aiming an interface I26 defined between an amount of lubricant present in
the tank 26 and the air present above this amount. This sensor 50 also uses the LIBS
technology.
More specifically, as visible in Fig. 12, the sensor 50 comprises a control unit 50A,
an emitter 50B of a laser beam directed towards the interface I26, as illustrated by the
10 arrows F2, as well as a receiver 50C capable of receiving a beam emitted in return, from
the interface I26 and illustrated by the arrows F2R. The laser beam F2 emitted by the
emitter 50B excites the amount L1 of lubricant and during de-excitation, an emission of a
characteristic spectrum of this amount L1 occurs as a beam F2R emitted in return. The
components 50B and 50C of the sensor 50 are integrated to an upper wall 262 of the tank
15 26 and connected to the unit 50A through two wired connections 50D and 50E.
This technology allows the sensor 50 to determine the dissolved iron content of the
oil contained in the tank 26, more particularly the content of Fe2+ and Fe3+ ions. This
allows determination of the degree of corrosion of the portions of the engine in contact
with the oil and, consequently, initiation of preventive or corrective maintenance actions if
20 required.
Alternatively, another type of sensor 50, also allowing determination of the
dissolved iron content of the oil contained in the tank 26, may be used. In this case, this
sensor may be integrated to the second line 42, notably positioned downstream from the
basicity index sensor 48.
25 The operation of the installation 2 is the following:
By default, the valve 20 is open and the valves 32 and 44 are closed, while the
distributor 62 is in the configuration illustrated in Fig. 6 where it insulates the inner volume
V26 of the tank 26 from the compressed air source 12 and from the ambient atmosphere.
When it should be proceeded with the determination of the basicity index of the oil
30 leaving the engine M, the unit 22 activates the valve 20 by means of the signal S20 in a
first step, in order to bring it into a closed configuration as illustrated in Fig. 7. In this
configuration, oil is present in the first bypass line 28, between the filter 30 and the valve
32, because of an unplugging operation of the filter 30, carried out earlier and which is
explained hereafter.
35 In this configuration, the valves 32 and 44 and the distributor 62 are closed.
15
The level sensor 60 is positioned so that, when the oil column retained in the
conduit 4 upstream from the valve 20 attains the level N0 detected by this sensor, as
illustrated in Fig. 8, a predetermined amount of lubricant L’ is present above the mouth
282. For example, the predetermined amount may be equal to 100 ml. When the level
sensor 60 detects that this 5 level N0 is attained in the conduit 4, the inner volume V26 of
the tank 26 is set to atmospheric pressure by actuating the distributor 62 in order to bring
it into the configuration of Fig. 8.
From this configuration, the unit 22 controls the valve 32 and the distributor 62 in a
following step for achieving transfer of the amount of oil L’ from the conduit 4 to the tank
10 26, as illustrated by the configuration of Fig. 9. In this configuration, the valve 32 is open,
while the distributor 62 is closed. The transfer of oil from the conduit 4 to the buffer tank
26 is therefore accompanied by an increase in the air pressure inside the tank 26. The
compression level of the air trapped in the tank may be related, after calibration, to the
initial volume of air in the tank 26 and to the volume of transferred oil.
15 For example, for adiabatic compression and an initial volume of air in the tank 26
equal to 160 ml, the pressure in the tank 26 attains 1.7 bars absolute for 50 ml of
transferred oil.
Also, by considering a tank 26 initially containing 250 ml of air, it is possible to
transfer 80 ml, i.e. the amount L1 illustrated in Fig. 10, into the tank 26 before attaining in
20 the upper portion of the latter an air pressure P1 equal to 1.7 bars absolute. This is the
example considered in the following.
In this case, the level of oil N2 is attained in the tank 26 at the step illustrated by
the installation 2 in the configuration of Fig. 10.
The unit 22 then automatically controls the valves and the distributor in order to
25 attain the configuration of Fig. 11 where the tank 26 is set under pressure through the
distributor 62 which connects the volume V26 to the compressed air source 12, so that the
air pressure P1’ inside the tank 26 becomes equal to 7 bars. In order that this may occur,
the valve 32 was switched beforehand by the unit 22 into the closed configuration, in order
to avoid a return of oil from the tank 26 to the duct 4. Moreover, in this step, the valve 20
30 is switched by the unit 22 into an open configuration, so that the flow of oil from the engine
M to the recovery pan 6 may again occur in the direction of the arrow F1. Still in this step,
the sensor 50 is used for measuring the dissolved iron content, notably the Fe2+ and Fe3+
ion content, of the amount L1 of oil present in the tank 26.
16
To do this, the sensor 50 aims the oil/air interface I26 which is located at the level
N2 in the tank 26. The output signal S50 of the sensor 50, or a signal extrapolated from
this signal, is integrated to the output signal S2 of the installation 2.
From this configuration, the unit 22 controls the distributor 62 and the valve 44 by
means of the signals S62 and S44, for 5 closing the distributor 62 and opening the valve 44
respectively and thereby attaining the configuration of Fig. 13 wherein the oil content in
the tank 26 is gradually driven out of the latter because of the pressure P1 prevailing in
the upper portion of the inner volume V26.
The oil therefore flows through the sensors 46 and 48 which are capable of
10 detecting the parameters for which they are provided and of providing corresponding
signals S46 and S48 to the unit 22, like in the first embodiment.
The discharge of the oil contained in the tank 26 through the second discharge line
42 may take place in several cycles, by successive expansions of the air volume trapped
in the tank and successive connections to the air source 12. For a tank of 250 ml initially
15 containing 80ml of oil, it is possible for example to carry out three successive expansions,
between 7 bars and 6.2 bars, preceded with three connections to the air source 12. This
allows delivery of a total volume of 50 ml in the second discharge line 42 and attaining the
configuration of Fig. 14 wherein a residual amount L2 of 30 ml of lubricant, remains in the
tank 26 while being subject to a pressure P2 equal to 6.2 bars.
20 The three successive expansions take place by filling up beforehand and
successively the tank 26 with air at 7 bars, by means of a suitable command of the
distributor 62.
These three expansions give the possibility of circulating 50 ml of lubricant in the
sensors 46 and 48 in three successive steps, which allows them to generate three sets of
25 signals S46 and S48 or a set of combined signals, intended for and provided to the unit
22, and then transmitted and/or processed like in the first embodiment.
From the configuration of Fig. 14, the unit 22 causes the installation 2 to pass into
the configuration of Fig. 15 wherein the inner volume V26 of the tank 26 is again
pressurized to the pressure P1’ of 7 bars, in return for a suitable command of the
30 distributor 62, while the valve 44 is closed.
Once this operation has been completed, the unit 22 orders the valve 32 to open
and the distributor 62 to close, which has the effect of driving out the oil present in the
lower portion of the tank 26 through the first bypass line 28, as far as into the conduit 4, in
a direction for unplugging the filter 30. This step is illustrated by the configuration of Fig.
35 16. By lowering the pressure in the tank 26 from 7 to 6.2 bars, it is possible to have an
17
amount of about 20 ml of the tank 26 circulate towards the conduit 4. At the end of this
step, there remains an amount L3 equal to 10 ml of lubricant in the tank 26, under a
pressure P2 of 6.2 bars.
Once this unclogging operation of the filter has been completed, the unit 22 causes
the installation 2 to switch into the configuration of 5 Fig. 17 wherein the valve 32 is again
closed, while the valve 44 is open and the distributor 62 is placed in a configuration for
supplying the volume V26 with pressurized air. This has the effect of discharging the
residual amount of oil present in the second discharge line 42 and in the sensors 46 and
48 until the configuration of Fig. 18 is obtained wherein the second discharge line 42 and
10 the sensors 46 and 48 are emptied of oil and filled with air. This corresponds to the
configuration of Fig. 7 mentioned above.
It is noted in figs. 17 and 18 that the portion of the first bypass line 28 located
between the valve 32 and the outflow mouth 284 is emptied by the air from the tank 26.
This is to be related to the fact that in practice, the valve 32 is immediately positioned
15 upstream from the junction 29.
In the third embodiment of the invention illustrated in Fig. 19, several conduits 4
are used, each of them being provided for collecting the oil from a single cylinder of the
engine M.
Each conduit 4 is equipped with a valve 20 controlled by the electronic unit 22 and
20 which gives the possibility of interrupting the flow of a stream F1 of lubricant in the
relevant conduit 4. A first bypass line 28 is connected, to each conduit 4, upstream from
its valve 20 on the one hand and to the inlet of the buffer tank 26 on the other hand, which
is the same as in the first embodiment. The installation 2 therefore comprises as many
bypass lines 28 as there are conduits 4. Starting from its mouth 282, each bypass line 28
25 is equipped with a filter 30 and a stop valve 32. The first four lines 28 join up downstream
from their respective stop valves 32 and the tapping orifice 34 is common to the first four
bypass lines 28, as well as their outflow mouth 284 in the buffer tank 26.
A tapping orifice 8 is provided on each conduit 4 and equipped with a manually
controlled valve 10, according to an approach parallel to the one mentioned above
30 concerning the first embodiment. Alternatively, only one or certain conduits 4 are
equipped with such a tapping orifice 8.
The second discharge line 42 is common for all the cylinders of the engine and
receives, downstream from the tank 26, the oil from all the first bypass lines 28. The
outflow mouth 424 of the second discharge line is positioned on one of the conduits 4,
35 downstream from its stop valve 20.
18
This third embodiment allows optimization of the size of the conduits 4 and their
pathway within the engine compartment of a ship. This allows a gain in room as compared
with the first embodiment.
By successively applying the method explained above concerning the first
embodiment, for each of the conduits 4, 5 the installation of this third embodiment gives the
possibility of determining, by means of the sensor 50, identical with the one of the first
embodiment, the iron content of the fuel at the outlet of each of the cylinders of the engine
M on which is connected a conduit 4.
In the example of Fig. 19, four conduits 4 are provided, each dedicated to a
10 cylinder of the engine M. Alternatively, the number of conduits 4 is different, while
remaining greater than or equal to 2, in order to adapt the installation 2 depending on the
configuration of the engine M and on the available space for housing the conduits 4.
Regardless of the embodiment, the sensors 46 and 48 are optional, in the sense
that they are not useful for determining the dissolved iron content of the oil. However they
15 are highly advantageous since they give the possibility to the installation 2 of automatically
carrying out several measurements of several represented parameters of the quality of the
oil, in addition to the sole dissolved iron content. Thus, the installation 2 allows an efficient
measurement of the dissolved iron content, of the basicity index or BN and/or of other
parameters of an oil leaving the engine M by means of a method which may be automated
20 and which does not require any particular knowledge on behalf of a user, since the signal
S2 may be directly legible, either by man or by a machine.
In practice, the maximum pressure P1’ prevailing in the inner volume V26 of the
tank 26, which depends on the pressure of the source 12, is not limited to 7 bars. It is
comprised between 6 and 12 bars, preferably between 7 and 10 bars depending on the
25 pressure of the compressed air network available on the ship. The value of 7 bars is
preferred since it gives good experimental results and corresponds to a currently available
pressure level. It is important that this pressure P1 be greater than the pressure P4 of the
oil in the conduit 4, which is comprised between 1.1 and 6 bars as mentioned above.
Indeed, it is the difference between the pressures P1 and P4 which ensures the flow of
30 the oil through the second discharge conduit 42.
Regardless of the embodiment, the installation 2, which is essentially comprised in
the casing 24, is easy to install on board a ship and does not require the setting into place
of the valve 20 in the conduit 4, the junction of the lines 28 and 42 on this conduit and its
supply with current and pressurized air. The installation 2 may therefore be easily
35 implanted on a new ship or used for retrofitting an operating ship.
19
The invention is described above in the case of its use for a ship propulsion
engine. However it may be applied to other pieces of equipment, for example an auxiliary
or ancillary ship engine, as well as a gearbox, notably of a tidal or wind turbine.
In the foregoing, the terms « oil » and « lubricant » are used indistinctly since an
engine oil is a 5 lubricant. The invention may however be applied to other lubricants such as
oils for transmissions and for gears, oils for compressors, hydraulic oils, turbine oils or
further oils for centrifuges.
The features of the embodiments and alternatives contemplated above may be
combined for generating novel embodiments of the invention.

I/We Claim:
1.- An installation (2) for following up the evolution of the quality of a lubricant
circulating in a piece of 5 equipment (M), this installation comprising:
- at least one conduit (4) for circulating (F1) the lubricant, this conduit being
connected upstream to the piece of equipment and downstream to a recovery
pan (6)
characterized in that the installation comprises:
10 - a first controlled valve (20) for interrupting the circulation (F1) of the lubricant in
the conduit (4),
- a buffer tank (26) for accumulating the lubricant,
- a first bypass line (28) connected to the conduit, upstream from the first valve
on the one hand and to the buffer tank on the other hand,
15 - a second controlled valve (32) for interrupting the circulation of the lubricant in
the first bypass,
- a second line (42) for discharging the lubricant, from the buffer tank to the
recovery pan,
- a third controlled valve (44) for interrupting the circulation of the lubricant in the
20 second discharge line
- a sensor (50) for determining the dissolved iron content of an amount (L1) of
lubricant contained in the buffer tank (26).
2.- The installation according to claim 1, characterized in that the sensor operates
25 according to the laser-induced breakdown spectroscopy (or LIBS) technology.
3.- The installation according to claim 2, characterized in that the sensor (50)
comprises:
- an emitter (50B) capable of emitting a laser beam (F2) towards an interface
30 (I26) between the amount (L1) of lubricant contained in the buffer tank (26) and
an amount of air contained in the buffer tank (26),
- a receiver (50C) intended for receiving a beam (F2R) emitted in return, from the
interface.
21
4.- The installation according to one of claims 2 or 3, characterized in that the
sensor (50) is installed in the upper portion (262) of the buffer tank (26).
5.- The installation according to one of the preceding claims, characterized in that
it comprises at 5 least one other sensor (46, 48), positioned on the second discharge line
(42) and capable of determining a physico-chemical parameter (D, V, H, T, BN) from the
amount (L1) of lubricant contained in the buffer tank.
6.- The installation according to claim 5, characterized in that the second sensor is
10 selected from among
- a sensor (46) for measuring density (D), viscosity (V), humidity (H) and
temperature (T),
- a basicity index (BN) sensor (48).
15 7.- The installation according to one of the preceding claims, characterized in that
it comprises means (12, 22, 36, 40 ; 12, 22, 62) for gas pressurization of the inner volume
(V26) of the buffer tank (26), notably a source of compressed air (12) and a set of valves
(36, 40) or a pneumatic distributor (62) for selectively putting into communication the inner
volume (V26) of the buffer tank (26) with the source of compressed air or the ambient
20 atmosphere.
8.- The installation according to one of the preceding claims, characterized in that
it comprises means (54, 56 ; 60) for detecting the lubricant level in the buffer tank (26),
notably a gas pressure sensor (60) in the inner volume (V26) of the buffer tank (26).
25
9.- An automated method for following the evolution of the dissolved iron content
of a lubricant circulating in a piece of equipment (M), by means of an installation (2)
according to one of the preceding claims, characterized in that it comprises at least steps
of:
30 a) closing the first valve (20),
b) opening the second valve (32) and closing of the third valve (44) for supplying
the buffer tank from an amount (L; L’) of lubricant accumulated in the conduit
(4), upstream from the first valve,
c) using the sensor (50) for determining the dissolved iron content of the amount
35 (L1) of lubricant contained in the buffer tank (26).
22
10.- The method according to claim 9 , characterized in that
- 5 it is applied with an installation (2) according to one of claims 5 or 6,
- it comprises an additional step d), posterior to steps a) and c) and consisting
of:
d) opening the third valve (44) so as to circulate the lubricant present in the
buffer tank (26) through the second discharge line, in contact with the
10 second sensor (46, 48).
11.- A method for following the operation of an onboard piece of equipment (M) on
a ship, characterized in that it comprises the determination, on board of the ship, of the
dissolved iron content of a lubricant from the piece of equipment by applying a method
15 according to one of claims 9 or 10.