FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION An Oil Separator For Internal Combustion Engine


APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

INVENTORS
Mr. M.D Peshave, Mr.A.A Athawale
and Mr. P.V. Yarsam
All are Indian Nationals
of TATA MOTORS LIMITED,
an Indian company having its registered office
Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification describes the invention.


FIELD OF INVENTION
The present invention relates to a nove] oil separator for two cylinder direct injection high pressure common rail diesel engine which can specifically be used to separate the substantial amount of the oil carryover from the crankcase blow by gases where the magnitude of oil contamination in blow by gases is high and that may be present in any form of oil e.g. oil mist, droplets, particles, oil film etc. This novel oil separator concept is applicable to closed crankcase ventilation system of a turbocharged or naturally aspirated two cylinder direct injection high pressure common rail diesel engine for passenger car where the crankcase pressures are dynamic in its behavior.
BACKGROUND OF THE INVENTION
Oil separator in IC engines is mostly used for separating the oil that may be present in any form of its existence e.g. oil particles, contaminants, oil droplets or mist or layer of the oil from the blow by gases coming out from the engine crank case. It is not the healthy situation for any engine which contains oil in the blow by gases which are either re-circulated or emitted into the atmosphere .Oil droplets / particles entering into the engine & burning thereby into the combustion chamber may lead to following harmful effects:
o Heavy engine emissions ( in terms of unburnt HC , Smoke )
o Continuous and sustained oil burning can lead to the coking of the oil and
thereby resulting into deposition of carbon particles in the rings.
o Sustained operation of engine under oil burning conditions could lead to
piston ring stickiness. Thus prevents its prime function and reduces the life of
the rings.
o This may also lead to leakage of compression and thereby loss of power and
subsequently heavy blow by rates.
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o This loss of power due to oil burning not only leads in increasing the
emissions but also engine oil consumption rate.
o If the rate & quantity of oil burning in the combustion chamber is more / high
in certain situations e.g. climbing up the gradient/ sudden accelerations /
decelerations it can lead to uncontrolled combustion.
Further the oil particles deposition onto the inner surfaces of intercooler can reduce the cooling effectiveness & thereby increases thermal loads on the engine in case of turbocharged intercooled diesel engine application.
In past various methods & arrangements have been used to extract the oil from the blow by gases. In many of the oil separators, oil is separated by directing the mixture of oil & blow by gases such that the flow of the mixture is exposed to sudden change in flow area, restricted path, change in the direction of flow path, impacting the mixture on a wall or the surface or by directing the gas flow in vortex or other form e.g. cyclonic, Centrifuge by which the oil droplets looses its energy and gets separated from blow by gas. Impact or Inertia separators, Diffusion separators, Spiral & Cyclonic separators are the examples of the above methods. These are henceforth referred as conventional oil separator in this paper.
Oil being denser, after impinging on to any surface it looses its energy and accumulates in the bottom most portion of the housing, from where it can be returned back into the oil reservoir or oil sump.
In a typical compact two cylinder diesel engines where the crankcase volumes and oil pan area are small or moderate , the crankcase pressures will be more dynamic in behavior which affects the oil carryover in blow by gases from crank case. Also the crankcases are more sensitive to positive pressures.
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Conventional separators become less effective to separate the oil when blow by gas is mixed with substantial amount of oil in it, especially where the crankcase volume is small or moderate.
Although some complicated design or arrangement oil separators can be used for this purpose but it may not be a cost effective & limited due to its practical adaptations to a smaller engines having small crankcase volume capacities and with high rate of pressure fluctuations.
SUMMARY OF INVENTION
Therefore the present invention overcomes these limitations by providing a novel oil separator which is very simple and robust in construction which would be the most cost effective as well as adaptable to the engines of such type. The present invention oil separator gives better oil separation effectiveness as well as ensures the positive return of oil back into the sump or reservoir while assisting in boosting the overall engine and vehicle performance. The limitation or the possibility of having back pressure effect by putting the oil separator in the blow by gas path is also eliminated by this invention.
Also the present invention can be used to separate large oil droplets from the blow by gases reliably.
Accordingly the prime objective of the present invention is to provide a novel oil separator which has maximum oil separation efficiency or which is more promising as regards to the oil separation from the blow by gases that are vented out from the crank case and are contaminated with substantial amount of oil.
Another objective of the present invention is to provide a new oil separator which is simple & robust in construction as well as cost effective .
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Yet another objective of the present invention is to provide a new oil separator which assists in evacuating the blow by gases with a very high rate and thereby keeps the pressures in the crankcase enough below the atmospheric pressure by 20 to 25 mbar at all the operating conditions of the vehicle and engine in connection with the turbocharged diesel engines operating under closed crank case ventilation system.
Another objective of the present invention is to provide a new oil separator along with the oil drain system that ensures positive drainage of the separated oil back into the oil sump or reservoir under all the operating conditions of the engine.
In conjunction with all the above objectives and many other objectives , this system includes a novel oil separator and the oil drainage system which can be adapted in the path of the blow by gases coming out from the crankcase.
The oil separator further comprises of 5 major components ; a vertical cylindrical housing that forms the enclosure body of the oil separator , to the bottom of which the inlet pipe or port is located. The outlet pipe which is a perforated tube located in the upper portion of the cylindrical housing. The inlet and outlet ports are separated by the Separation chamber ; which consist of a perforated tube covered with the 2 layers of fine screen steel wire mesh and the deflector body at its lower end. At bottom surface of the cylindrical housing the oil drain tube/pipe is connected.
The mixture of oil & blow by gases coming out from the crankcase are exposed to enter the oil separator housing in upward direction through the inlet port or pipe at the bottom. This mixture impinges against the baffle plate of the separation chamber and flows along the impingement surface of the baffle plate. The oil mist or particles being dense after impingement forms fewer & larger droplets and falls down and gets accumulated on the bottom surface of the housing. The deflector is shaped such that these droplets falls down on the oil drain tube opening. Thus the accumulated oil is
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returned back into the system via drain pipe. The substantial portion of oil is removed in this stage.
Further the remainder of the oil & gas particles moves towards the air gap between the separation chamber and the inner wall surface of the housing. As the stream of gas and oil vapor particles flows through this , the oil mist adheres/coalesces to the inner wall surface of the cylindrical housing and forms a layer which ultimately moves down; being heavier and collects in the pool of oil which was already separated in the 1st impingement against the baffle plate. The gases flowing through this gap are then forced to change its direction of flow to 90 degrees before being entered into the separation chamber.
The separation chamber consists of a perforated tube having plurality of small diameter holes covered with 2 layers of fine screen steel wire mesh. The diameter of the holes and the number of holes makes the flow of blow by gases being accelerated as it passes through it.
During its flow through the separator chamber, the gases are impinging on the perforated tube via fine screen wire mesh wherein the further fine particles of oil are trapped & restricted to flow further. Thus they are separated before being entered into the separation chamber volume. This ensures effective oil removal from the blow by gases. Thus the gases that are present in the separation chamber volume are free from any oil contamination and are much cleaner to recycle back into the combustion chamber.
The cleansed blow by gases thus present in the separation chamber volume are then absorbed by the outlet port which is located at the top of the separation chamber as well as the housing of an oil separator. The outlet port is again a perforated type tube which is closed from its bottom and has opening holes of smaller diameter on its periphery. The cleansed blow by gases present in the separation chamber are then
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forced to change its direction of flow path again to enter into the outlet port. The gases that are present in the upper portion are absorbed and sent out of the oil separator as a clean blow by gas for recirculation into the combustion chamber.
The extracted oil is accumulated at the bottom of the housing and drained back into the system through the oil return vent tube. To ensure positive oil return or drain, the return tube or vent is connected to a point in the oil sump which is always well immersed below the oil level and near to the suction strainer of the oil pumping system, which will always pull the accumulated oil back into the system.
This novel oil separator uses the gas dynamics principles e.g. sudden enlargement, sudden contraction of the flow opening areas , flow path deflection , diffusion and absorption methods for directing the flow path of the oil and blow by gas mixture and to separate the oil from it.
The mixture of oil and blow by gas as it passes through all these, it looses its kinetic energy. The crankcase pressures will further reduce as the evacuation of the blow by gases from the crank case with this kind of oil separator is very high. This helps to maintain the crankcase pressures enough below atmospheric by 20 to 25 mbar. By maintaining enough negative pressures at all the operating conditions it improves the overall engine performance by 5 %.
The effective evacuation of blow by gases as well as the effective oil separation from blow by gases is the major advantage of this type of oil separator.
As the rate of blow by gases evacuation is very high and effective with this oil separator, it not only separates the oil but also improves the overall performance of the engine as mentioned below while ensuring the positive oil drainage back into the system.
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o By successful separation , it is now ensured that oil particles entering into the
combustion chamber are reduced and thereby reduction in engine /vehicle out
emissions i.e.effects of oil burning on emissions are eliminated.
o Stabilized engine oil consumption rate.
o Reduction in coking of oil particles on piston rings & thereby reducing rings
stickyness thus longer life for piston rings.
o Oil leakages from sealing joints can be prevented significantly e.g. Oil sump
gasket,Crankshaft front & rear oil seal, cylinder head cover and cylinder head sealing
joints as the pressures acting on them have now fallen down.
o Oil entry to the compressor wheel is also avoided and hence damage to the
compressor wheel is prevented.
o Breathing of the engine is improved.
o By maintaining small & enough vaccum at all the operating conditions in
healthy manner the turbocharger seals are also protected. This helps in avoiding any
damage to turbocharger seals due to excessive pressures.
o Due to improved pressure balance in the sump and the cylinder block the
overall oil drainage improves.
The number of holes and diameter of the holes on outlet port, on perforated tube of separation chamber, air gap distance between the inlet port & deflector plate, air gap distance between the separation chamber & cylindrical housing, number of layers of fine screen wire mesh are the design parameters for the present invention oil separator.
The other advantages and features of the present invention can be seen in details with the explanation of following detailed drawings and the embodiments.
In another embodiment of the present invention the flow path of the blow by gas & oil mixture through the inlet port is further modified to have fine oil separation. The
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inlet port is a perforated tube having limited number of small diameter holes on its periphery & the exit diameter is restricted by reducing the opening area.
The flow directions are divided into two directions, one part moves in centrifugal direction through the smaller diameter holes & impinging on to the inner wall surface of cylindrical housing & thus increases the formation of oil droplets to ease the separation. Another part moves in vertical direction with restricted opening area & impinges on the deflector surface. The separation of oil particles will be improved with this, in the initial stages itself by using centrifugal impingement of the part of the blow by gases & oil mixture.
After this impingement the blow by gases passes through the air gap between separation chamber & the inner wall surface of the cylindrical housing. Further fine particles of oil are screened off as it passes through fine screen wire mesh of the separation chamber. These cleansed blow by gases are then absorbed by the outer port located at the top & sent to the combustion chamber via cylinder head cover baffle plate. The drained oil is then returned back into the system via oil return vent tube.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is the schematic/ diagrammatic representation or layout of the blow by gases path including the present invention novel oil separator & the oil separation mechanism wherein oil gets separated , collected . & drained back positively into the system from the mixture of blow by gases & oil coming out from the crankcase of a two cylinder direct injection high pressure common rail turbocharged diesel engine operating under Close Crankcase Ventilation system.
FIG.2 Is the Front cross sectional view of the present invention oil separator.
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FIG. 3 is the Front cross sectional view of yet another alternate embodiment of the oil separator embodying the present invention
DETAILED DESCRIPTION OF DRAWINGS
Now referring to the FIG. 1 wherein the complete schematic layout of the blow by
gases oil from the & oil mixture flow path is illustrated that uses the present invention oil separator for separating the oil effectively from blow by gases that are coming out from the crankcase of a two cylinder direct injection high pressure common rail turbocharged diesel engine using Closed Crankcase Ventilation system. (CCV)
The turbocharged diesel engine 1 operating under CCV system as shown in layout carries the blow by gases outlet path 2, from the crankcase leading into the inlet port of the present invention oil separator 3, wherein the mixture of oil & blow by gases is forced to flow through it by using, diffusion, deflection, inertial separation, Coalescing techniques of oil droplets separation from blow by gases .Large as well as fine particles of the oil are separated in this & the separated oil is drained back into the oil sump / reservoir 6 of the diesel engine 1 via return line 4. The cleaned blow by gases are then carried out of the oil separator 3 & sent into the cylinder head cover 7 via line 5.
The cleaned blow by gases thus entering into the head cover 7 are then expelled out via line 8 after inertial separation of oil particles by passing through a baffle plate type arrangement in head cover 7. The cleaned blow by gases are then mixed into the air intake system of the engine at junction point 13 of the fresh air intake line 9. Thus the cleaned blow by gases are recycled back into the combustion chamber via line 14 where it burns completely.
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The air filter 15 is provided to filter the fresh air going into the engine. The turbocharger 11, in which the exhaust gases coming out from the engine via line 10 are expanded & after doing work on turbine it exits into the muffler system of the vehicle. On the other side, compressor wheel sucks fresh air via line 9 & is fed into the combustion chamber.
The oil return line 4 is connected into the oil reservoir 6 ; well below the minimum-level of the oil for positive return of oil back into the system.
Now referring to FIG. 2, wherein the numerical number designates the components of the present invention oil separator. The oil separator embodying the present invention is generally designated by numerical 3.
This oil separator 3 comprises of Cylinder housing 20 having bottom wall 21 & top cover wall 22, Inlet port 26 located at the bottom of the housing, Separation chamber assy. 41 , Outlet port 27 located at the upper portion of the housing, & the oil return vent tube 28.
The separation chamber assembly 41 carries three major components, deflector 25, vertical perforated tube 24, lapped by two layers of fine screen steel wire mesh 23 onto it. The perforated tube 24 carries number of perforations of smaller diameter holes 31 on to it. The diameter of holes & the number of holes on the perforated tube 24 are selected such that it keeps the sufficient flow of gases while minimizing the back pressure by putting oil separator in the blow by gas path.
The mixture of oil & blow by gases 35 coming out from the crankcase of the turbocharged diesel engine are exposed to enter into the oil separator 3 through an oil inlet port 26 in upward direction. This mixture entering into the oil separator 3 is first impinges against the deflector plate 25 and flows along the impingement surface of the deflector plate 25. After impingement on the deflector plate 25, oil looses its kinetic energy, increasing its inertia to flow further. And also oil being dense
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material, oil droplets are formed in fewer & larger, falls down & gets accumulated on the bottom wall surface 21 of the cylindrical housing 20. The deflector 25 is shaped such that the portion of the oil droplets falls down on the top of the oil drain tube opening 42 provided on the bottom wall 21 of the cylindrical housing 20. The deflector can be part of the separation chamber assembly 41 or a separate deflector which can be fitted to the inlet port 26. Thus the accumulated oil 32 is drained back into the system via oil return tube 28 which is further dipped into the oil reservoir 40 via a flexible hose 39.
Thus substantial portion of the oil droplets gets separated at this stage using diffusion & inertial separation techniques. Further the mixture of oil & blow by gas moves in upward direction towards the air gap 33 between the separation chamber assembly & the inner side walls 37 of the cylindrical housing 20. As the stream of oil & blow by gas particles passes through this air gap 33 in upward direction, the oil mist particles adhere to the inner side wall surface 37 & coalesces down by forming a layer which ultimately moves in downward direction being heavy & collects in the pool of oil 32 which was already existing due to the oil separation in 1st impingement against the baffle plate 25. The remaining gases are then moved upwards being lighter & hits to the bottom annular surface of the top wall 22 of the cylindrical housing 20.
These gases are then forced to change their directions by approximately 90 degrees before being entered into the separation chamber assembly 41.
By this phase, substantial portion of oil is separated from blow by gases. Thus ensuring sufficient evacuation as well as separation.
The blow by gases after this phase are then entering into the separation chamber inner volume area 43, after its impingement on to the perforated tube 24 via fine screen wire mesh 23 ; wherein further fine particles of oil are trapped & restricted to
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flow further. Thus the gases entering into the separation chamber volume area are free from any oil contamination.
These gases accumulated in the bottom portion of the separation chamber volume 43, further flows in upward direction. These gases are absorbed through outlet port 27 which is located in the upper portion of the cylindrical housing 20 as well as the separation chamber assembly 41. The outlet port 27 is a perforated tube carrying holes and it is closed from the bottom side by a deflector plate 29 which forces the gases to flow in the air gap passage 38 between outlet port 27 & the perforated tube 24 of the separation chamber assembly 41 (by giving one more deflection to the path of the blow by gases).
In outlet port tube 27, holes are placed in axes perpendicular to each other; so that the light blow by gases that are present in the upper portion of the separator chamber volume 43 moving upwards are forced to change its direction of flow path again to enter into outlet port 27.
The blow by gases 36 thus coming out of the outlet port 27 are free from any oil contamination & are clean to sent back into the combustion chamber.
The separated oil accumulated in the bottom portion of the cylindrical housing 20 is then drained back into the system via an oil vent tube 28 which is connected deep into the oil reservoir 40 near the suction strainer of the oil pump to ensure positive oil sucked back into the system.
Another embodiment of the present invention is explained in FIG. 3.
Now referring to FIG.3 showing alternate embodiment designated by numeral 4 , which comprises of cylindrical housing 20 having bottom wall 21 & top cover wall 22, Inlet port 26 located at the bottom of the housing, Outlet port 27 located at the
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upper portion of the housing, Separation chamber assy. 41 & the oil return vent tube 28.
The inlet port 26 is modified to have further fine oil separation. The inlet port 26 carries limited number of holes 45 on its periphery & the exit diameter 47 is reduced by providing restriction with the addition of plate 46 in the gas flow path 35.
The inlet blow by gas flow path 35 , through inlet port 26 is now divided into two directions.
The flow path 48 which moves radially outwards through the smaller diameter holes 45 and impinges on to the lower inner wall surface 37 of the cylindrical housing 20. This increases the formation of oil droplets to ease the separation & to improve the oil separation in the initial stages itself.
Another flow path 49 moves in the vertical direction upwards through exit opening diameter 47 of inlet port 26 and impinges on the inner wall surface of the deflector plate 25. After impingement of blow by gas path 49 on to the deflector plate 25, further oil droplets looses its energy & increases resistance to flow further. Thus oil droplets are formed in fewer & larger. These oil droplets falls down and accumulates on the bottom wall surface 21 of the cylindrical housing 20.
This method of dividing the blow by gas flow in two directions improves the oil separation by separating substantial amount of oil in the initial stage itself.
The deflector 25 is shaped such that the portion of the oil droplets falls down on the top of the oil drain tube opening 42 provided on the bottom wall 21 of the cylindrical housing 20. Thus the accumulated oil 32 is drained back into the system via oil return tube 28 which is further dipped into the oil reservoir 40 via a flexible hose 39.
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The preferred embodiment ( FIGURE NO. 2 )and alternate embodiment shown in FIGURE NO. 3 has following concept separation stages.
The preferred embodiment ( figure no. - 2 ) has following concept. Stage 1: The mixture of the oil & blow by gases is exposed to the baffle plate which is directly facing the flow. After impingement of the mixture to the deflector plate, oil droplets or layers are formed in fewer & larger and falls down & accumulates in the lower portion of the cylindrical housing. The deflector is shaped such that oil falls down on the top of oil return tube opening which is situated at the bottom most point of the cylindrical housing. Substantial amount of oil is separated in this stage.
Stage 2: Further the stream of oil & blow by gases impinge on to the inner wall surface of the cylindrical housing during its flow through the air gap between separation chamber & the cylindrical housing by which the oil particles adhere to the inner wall surface & forms a droplet or layer which ultimately flows down into the already accumulated or separated pool of oil existing at the bottom portion & above the oil return vent tube.
Thus separated blow by gases may still contain fine oil particles which are then forced to enter into the separation chamber by changing the direction of its flow path , where it impinges on to the perforated tube having plurality of smaller diameter holes through the fine screen steel wire mesh. During its flow through wire mesh almost all the fine particles of the oil are restricted to flow further & thus only cleaned blow by gases are now existing into the separation chamber volume.
Stage 3: This system further uses the outlet port which is situated at the upper portion of the separation chamber and is again a perforated tube having limited number of holes so that only light / less density particles can pass through it. As it is situated at the top portion of the separation chamber it absorbs the cleansed blow by gases present inside the separation chamber wall. The blow by gases thus absorbed
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from the top portion of the separation chamber are free from the oil contamination before being sent further to combustion chamber.
Stage 4 - OIL RETURN :To ensure positive oil drain back into the system the oil return tube is connected to a point in the oil sump/reservoir which is well immersed below into the oil level & is near to the suction strainer of the engine which assists always to pull the accumulated oil back into the system.
The alternate embodiment ( Figure No. - 3 ) has different concept for Stage 1 separation as described below.
Stage 1: The mixture of the oil & blow by gases entering the oil separator through inlet port is further modified to have fine oil separation.
The flow directions are divided into two directions
• One part of blow by gas and oil mixture path moves out in centrifugal direction through the smaller diameter holes in the inlet port and impinging onto the inner wall surface of cylindrical housing ; thus increases the formation of oil droplets to ease the separation
• Another part of blow by gas and oil mixture moves in vertical direction through restricted opening area and impinges on the deflector plate surface.
After impingement of the mixture on to the deflector plate ,oil droplets or layers are formed in fewer & larger ; falls down and accumulates in the lower portion of the cylindrical housing.
The deflector is shaped such that oil falls down on the top of oil return tube opening which is situated at the bottom most point of the cylindrical housing.
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Thus ensuring maximum oil separation in the initial stage itself as compared to preferred embodiment.
The other 3 stages of the separation are similar as discussed in the Preferred embodiment referring to Figure no. 2.
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Dated this 23rd day of March 2009