JP5772402B2 - Oil separator - Google Patents

Description

  The present invention relates to an oil separator provided on a blow-by gas passage between an engine crank chamber and an intake system so as to separate oil mist from blow-by gas.

  In general, in an engine, blow-by gas flowing out from a combustion chamber into the crankcase is recovered and burned in the intake system of the engine without being released into the atmosphere. In this case, engine oil is present as mist (hereinafter referred to as oil mist) in the blow-by gas. Therefore, an oil separator is used in order to separate the oil from the blowby gas and return the oil to the lubrication required part in the engine without burning the blowby gas as it is.

  As this type of conventional oil separator, for example, a configuration as disclosed in Patent Document 1 has been proposed. In this conventional configuration, primary and secondary collision plates for separating oil mist are provided in a gas flow path inside the housing. Two drain pipes are provided at the bottom of the housing on the downstream side of each collision plate to collect the oil separated by each collision plate and return it to the engine. And the oil collected in each drain pipe falls in the engine from the hole of the bottom part of a drain pipe.

JP 2009-121281 A

  In this conventional oil separator, the oil separated by the primary and secondary collision plates as described above flows through the bottom of the housing and is collected in each drain pipe on the downstream side of the collision plates. Therefore, there is a possibility that the separated oil is mixed again into the gas flow while flowing through the bottom. In particular, in the part near the gas outlet connected to the intake system of the engine, since the negative pressure is large, the separated oil in the vicinity of the outlet has the gas flow even if it is collected in the drain pipe. It is easy to be mixed again. When no oil is collected in the drain pipe near the outlet, the blow-by gas in the upper space of the engine passes through the collision plate through the drain pipe and the housing due to a large negative pressure near the outlet. Without being sucked into the housing, it may be sucked into the intake system of the engine through the outlet from the housing. In such a case, the oil is not separated from the blow-by gas, and the unseparated oil enters the combustion chamber through the intake system of the engine. Furthermore, as described above, since the negative pressure is large in the portion close to the outlet of the housing, the drain pipe on the downstream side facing the outlet has a long vertical dimension, and the drain pressure must be increased unless the oil head pressure is increased. The collected oil in the pipe is difficult to fall into the engine. For this reason, it is necessary to lengthen the vertical dimension of the drain pipe. If this is done, the overall size is increased, and the mountability of the oil separator to the engine is deteriorated.

  The present invention has been made paying attention to such problems existing in the prior art. An object of the present invention is to provide an oil separator that can effectively prevent oil from re-scattering into gas.

In order to achieve the above object, the present invention provides an oil separator in which a plurality of separation portions for separating oil mist are provided along a gas flow path between a gas inlet and an outlet of a housing. A drain part for returning oil into the engine is provided at the bottom of the housing between the upstream side separation part and the downstream side separation part, and oil is placed on the bottom part of the housing between the downstream side separation part and the drain part. A concave portion for guiding to the drain portion is formed, and the bottom wall of the concave portion is inclined downward toward the drain portion and is inclined downward in the direction opposite to the gas flow .

  Therefore, in the oil separator of the present invention, the separated oil is guided to the recessed portion lower than the inner bottom surface of the housing and reaches the drain portion. For this reason, oil separated from the gas flow can be prevented from re-mixing as oil mist in the gas flowing through the gas flow path, preventing the re-scattered oil mist from being sucked into the intake side of the engine can do.

The said structure WHEREIN: The said recessed part is good to be formed in the position biased to the side in the width direction of a housing.
In the above-described configuration, the downstream separation section includes a wall portion provided with an orifice for increasing the flow rate of gas, and an oil catching portion facing the downstream side of the orifice, and the lower end portion of the wall portion is disposed on the bottom portion. It is good to form in the recessed part and to form the opening which can distribute | circulate oil in the lower end part.

The said structure WHEREIN: It is good to make the bottom wall of the said recessed part incline and descend toward the said drain part.
In the above configuration, a weir may be provided in the recess.

In the configuration of the previous reporting, the upstream separation unit may is impact separation type.

  As described above, according to the present invention, it is possible to effectively suppress the oil separated from the blowby gas from being mixed again in the blowby gas.

Sectional drawing which shows the oil separator of 1st Embodiment. Sectional drawing in the 2-2 line of FIG. Sectional drawing in the 3-3 line of FIG. Sectional drawing in the 4-4 line | wire of FIG. The partial plane sectional view showing the oil separator of a 2nd embodiment. The fragmentary sectional side view which shows the oil separator of 2nd Embodiment. The sectional side view which shows the oil separator of 3rd Embodiment. Sectional drawing in the 8-8 line of FIG. The partial sectional side view which shows the oil separator of 4th Embodiment. Sectional drawing which shows the oil separator of 4th Embodiment. The partial plane sectional view showing the oil separator of a 5th embodiment. The partial cross section figure which shows the example of change. Sectional drawing which shows another modification.

(First embodiment)
A first embodiment of an oil separator embodying the present invention will be described below with reference to FIGS.

  As shown in FIG. 1, the oil separator of this embodiment is integrally formed on a cylinder head cover made of a synthetic resin (not shown) of the engine, and on a blow-by gas path between the crank chamber of the engine and the intake system. Is arranged. The oil separator housing 11 is formed in a rectangular box shape as a whole by a bottom wall 11a, side walls 11b on both sides, end walls 11c on both ends, and an upper wall 11d. An inlet 12 that communicates with the crank chamber of the engine is formed at a side edge (see FIG. 2) near one end of the bottom wall 11a. An outlet 13 communicating with the intake system of the engine is formed at the side edge (see FIG. 4) of the upper wall 11d of the other end of the housing 11. During operation of the engine, the gas in the housing 11 is sucked into the engine intake system from the outlet 13 based on the intake action of the engine, and along with the suction, blow-by gas from the crank chamber side of the engine Flows into the housing 11 from the inlet 12. In the housing 11, an upstream side separation portion 14 and a downstream side separation portion 15 for separating the oil mist from the blow-by gas are provided along the gas flow channel between the inlet 12 and the outlet 13. Are arranged at intervals.

  As shown in FIGS. 1 to 3, the upstream separation portion 14 has an impact separation type configuration. That is, at the rear position of the inflow port 12 (right side in FIG. 1), a first flow path forming wall 16A erected in a partition shape is formed integrally with the bottom wall 11a and one side wall 11b. Its upper end is in proximity to or in contact with the upper wall 11d. The first flow path forming wall 16A may be integral with the upper wall 11d. A gap 18A is formed between the side edge of the first flow path forming wall 16A and the other side wall 11b. A second flow path forming wall 16B is formed integrally with the bottom wall 11a and both side walls 11b at a position where the inlet 12 is covered from above at an interval. The second flow path forming wall 16B has an upper plate portion 116 that is inclined upward and forward at an intermediate portion in the vertical direction in the housing 11. For this reason, a narrow space 18B positioned above the bottom wall 11a is formed between the upper plate portion 116 and the upper wall 11d, and the space 18B is formed to be tapered. An arcuate curved portion 216 is formed at the front end of the upper plate portion 116. Further, on the rear side of the second flow path forming wall 16B, an opening 316 close to the first flow path forming wall 16A is formed on the first flow path forming wall 16A side. Then, the gas from the inlet 12 flows so as to bypass the first flow path forming wall 16A from the lower surface side of the second flow path forming wall 16B, and moves from the opening 316 to the upper surface side of the second flow path forming wall 16B. Then, it flows in the space 18B between the upper plate portion 116 and the upper wall 11d. At this time, since the space 18B is formed to be tapered, the gas flow in the space 18B is increased as it goes forward.

A small oil discharge hole 11e is formed in the bottom wall 11a of the corner portion on the rear side of the second flow path forming wall 16B and opposite to the inlet 12.
On the front side of the first flow path forming wall 16A, a plurality of parallel collision plates 17 are formed on the upper wall 11d downward. The lower ends of these collision plates 17 are close to the upper plate portion 116 of the second flow path forming wall 16B with a small gap. The collision plate 17 is bent at a plurality of locations, and collision portions 17a to 17d where the gas flow collides are formed at the bent portions. A sub collision plate 117 is formed on each side wall 11b so as to face the bent concave portion of the collision plate 17 on the side wall 11b side. The presence of each collision plate 17 and sub-collision plate 117 narrows the flow path cross-sectional area of the space 18B, and the gas flow accelerated by the inclination of the upper plate portion 116 is further accelerated. The gas flow meanders along the unevenness between the collision portions 17a to 17d and the sub collision plate 117 of each collision plate 17, and collides with the collision portions 17a to 17d and the sub collision plate 117. The oil mist having a large particle size contained in the gas is separated from the gas and is captured on the collision plate 17 and the sub collision plate 117.

  As shown in FIGS. 1 and 4, in the downstream side separation portion 15, a wall portion 19 is formed integrally with the housing 11 so as to close the gas flow passage in the gas flow passage in the housing 11. . A plurality of orifices 19a for increasing the flow velocity of the gas are provided through the central portion of the wall portion 19 in the width direction. An oil capturing body 20 made of a fiber aggregate filter material is disposed in the housing 11 so as to face the orifice 19a of the wall portion 19 from the downstream side. Then, when the gas that has passed through each orifice 19a of the wall portion 19 collides with the oil capturing body 20 made of the filter material, the oil mist mainly having a small particle size contained in the gas is separated and captured by the oil capturing body 20. The A gap 25 for forming a gas flow path is formed between the oil trap 20 and the side wall 11b opposite to the outlet 13.

  As shown in FIGS. 1 and 2, oil is accumulated at a position that is laterally deviated from the center in the width direction of the bottom of the housing 11 between the upstream separating portion 14 and the downstream separating portion 15. A bottomed cylindrical drain portion 21 for returning to the inside is formed. A hole 21a for dropping oil is formed at the bottom of the drain part 21.

  As shown in FIG. 1 and FIG. 3, the position is deviated from the central portion in the width direction of the housing 11, and at the bottom of the housing between the oil catching body 20 and the drain portion 21 of the downstream separating portion 15. A recess 23 is formed. The bottom wall 23 a of the recess 23 is inclined downward toward the drain portion 21. A projecting portion 19 b that enters and fits into the recess 23 is formed at the lower portion of the wall portion 19 of the downstream side separation portion 15. An opening 24 for allowing oil to pass to the drain portion 21 side is formed at the lower end of the protruding portion 19b.

Next, the operation of the oil separator configured as described above will be described.
When the engine is operated and the gas in the housing 11 is sucked through the outlet 13 by the intake action of the engine, the inside of the housing 11 becomes negative pressure. For this reason, blow-by gas from the crank chamber side flows into the housing 11 from the inlet 12 and is separated upstream from the lower surface side of the second flow path forming wall 16B through the opening 316 as indicated by an arrow in FIG. Part 14 is reached. Then, the gas flow is accelerated at the upstream separation portion 14 and collides with the collision portions 17 a to 17 d of the collision plate 17 and the sub collision plate 117. In this way, when the gas collides with the collision plate 17 and the sub collision plate 117, oil mist having a large particle size contained in the gas is separated and captured on the collision plate 17 and the sub collision plate 117. The oil trapped on the collision plate 17 is moved to the front end side of the collision plate 17 together with the gas flow, and a part thereof flows down on the upper plate portion 116 of the second flow path forming wall 16B. Further, the oil trapped on the sub collision plate 117 flows down on the upper plate portion 116. The oil that has flowed down on the upper plate portion 116 is caused to flow toward the front curved portion 216 by a high-speed gas flow. The oil that has flowed to the front end side of the collision plate 17 flows down from the front end onto the curved portion 216. Then, the oil on the curved portion 216 flows down on the bottom wall 11 a and is then stored in the drain portion 21.

  When the drop pressure of the oil due to the head pressure of the oil in the drain part 21 exceeds the differential pressure between the inside of the housing 11 and the inside of the cylinder head cover, the hole 21a at the bottom of the drain part 21 enters the cylinder head cover. Oil falls. Part of the oil on the upper plate portion 116 of the second flow path forming wall 16B flows to the rear side due to the inclination of the upper plate portion 116 and is discharged into the cylinder head cover from the oil discharge hole 11e at the rear portion of the housing.

  The blow-by gas from which the oil mist having a large particle size is separated mainly in the upstream separation portion 14 reaches the wall portion 19 of the downstream separation portion 15 and passes through each orifice 19a of the wall portion 19 at a high speed. Sprayed toward the capturing body 20. Then, when the gas hits the oil capturing body 20 made of a filter material, oil mist mainly having a small particle size contained in the gas is separated and captured on the oil capturing body 20. The blow-by gas from which the oil has been separated is sucked into the combustion chamber from the intake system of the engine through the gap 25 from the outlet 13 and burned.

  On the other hand, the oil trapped by the oil trap 20 flows down from the oil trap 20 into the recess 23 of the bottom wall 11a of the housing 11 and is stored in the recess 23. When the gas flow is weak and the negative pressure in the housing 11 is small, such as when the engine is idling, the bottom wall 23a of the recess 23 is inclined toward the drain portion 21 through the opening 24 at the lower end of the wall portion 19 according to the inclination of the bottom wall 23a. Flowing.

In this way, oil is separated from the blow-by gas, collected in the engine, and used for lubrication.
And according to this embodiment, the following effects can be acquired.

  (1) In the upstream side separation part 14 in the housing 11, the blow-by gas flow is accelerated in the tapered space 18 </ b> B and collides with the collision plate 17 and the sub collision plate 117. For this reason, mainly oil mist having a large particle diameter is efficiently captured. Moreover, in the downstream side separation part 15, the blow-by gas flow which isolate | separated the oil mist with a large particle size is made high-speed by the orifice 19a of the wall part 19, and is capture | acquired by the oil capture body 20 which consists of filter materials. Therefore, oil mist having a small particle size can be captured efficiently. For this reason, the upstream and downstream separators 14 and 15 can effectively separate the oil mist having a large and small particle size contained in the blow-by gas.

  (2) The drain portion 21 is located below the curved portion 216 at the front end of the second flow path forming wall 16B with a large drop corresponding to the height of the second flow path forming wall 16B. For this reason, since the drain part 21 is away from the gas flow passing through the upstream side separation part 14, there is almost no possibility that the oil after separation in the drain part 21 is mixed again in the gas flow.

  (3) The oil separated by the downstream separation part 15 is collected in the drain part 21 through the recessed part 23 positioned lower than the inner bottom surface of the housing 11. For this reason, even when the engine is rotating at a high speed and a large amount of blow-by gas flows through the housing 11 at a high speed, there is almost no possibility that the oil will be mixed again into the gas flow. Moreover, since the bottom wall 23 a of the recess 23 is inclined downward toward the drain portion 21, the oil can be smoothly guided toward the drain portion 21. Furthermore, since the recessed part 23 is biased to the side in the width direction of the housing 11, it is away from the part where the flow velocity of blow-by gas is high. Therefore, it is possible to further reduce the risk of oil being mixed again in the gas flow.

  (4) The oil separated by the downstream separation part 15 is guided in the direction opposite to the flow direction of the blow-by gas flow so as to leave the outlet 13 of the housing 11 through the recess 23. Accordingly, the oil is guided in a direction in which the negative pressure is not high, and it can be suppressed that the oil is drawn into the gas flow and mixed therein.

  (5) A protrusion 19b protruding from the lower end of the wall 19 is fitted into the recess 23, and an opening 24 is provided at the lower end of the protrusion 19b. 21 is led. On the other hand, the blow-by gas passes through the orifice 19 a of the wall portion 19, but hardly passes through the opening 24 that is lower than the inner bottom surface of the bottom wall 11 a of the housing 11. In particular, when oil accumulates in the recess 23 and the opening 24 is blocked by the oil, the blow-by gas does not pass through the opening 24. Therefore, it can suppress that oil is drawn in and mixed in a gas flow.

  (6) The drain portion 21 is located on the upstream side of the blow-by gas from the outlet 13 and is located where the differential pressure between the housing 11 and the cylinder head cover is not so large. Therefore, since the drain part 21 is located where it is not necessary to secure the hydraulic head pressure of the oil, the vertical dimension of the drain part 21 is shortened to make the oil separator for the engine excellent in mountability. be able to.

  (7) Since the drain part 21 is located where the flow of the gas flow between the lower side of the second flow path forming wall 16B of the upstream side separation part 14 and the wall part 19 of the downstream side separation part 15 is weak. Even if a large negative pressure is generated around the drain portion 21 by the gas flow, the oil accumulated in the drain portion 21 can be prevented from being blown up. Even if the oil is blown up, the oil is received by the wall 19 and returned to the recess 23. Alternatively, even if the oil passes through the orifice 19 a of the wall portion 19, it is captured by the oil capturing body 20 and returned into the recess 23. As a result, re-mixing of the oil once separated into the gas flow can be suppressed.

  (8) As described above, the drain part 21 is located away from the outlet 13 between the upstream side separator 14 and the downstream side separator 15, and between the outlet 13 and the drain part 21. The wall 19 having only the orifice 19a is interposed in the wall. For this reason, the negative pressure around the drain portion 21 does not increase so much, and unlike the prior art of Patent Document 1, the oil is blown up by the negative pressure of the outlet 13 or the drain portion 21 where no oil is present. It is possible to prevent the gas in the engine from being sucked through.

  (9) Since the oil separated from the gas flow is divided and stored in the drain part 21 and the concave part 23, it is not necessary to increase the capacity of the drain part 21. For this reason, similarly to the above, the vertical dimension of the drain part 21 can be shortened to make the oil separator excellent in mountability. Moreover, even if the oil level in the recess 23 is higher than the oil level in the drain portion 21, the projection 19b between the wall portions 19 is located in the recess 23, so that the gas flow is blocked by the projection 19b. Is done. Therefore, oil removal in the recess 23 due to the gas flow is effectively prevented.

(Second Embodiment)
Next, a second embodiment of an oil separator embodying the present invention will be described. In addition, in each embodiment after this 2nd Embodiment and a modified example, it demonstrates centering on a different part from 1st Embodiment.

  In this 2nd Embodiment, as shown in FIG.5 and FIG.6, the structure of the upstream separation part 14 differs from 1st Embodiment. That is, in the second embodiment, the plurality of collision plates 17 of the upstream separation portion 14 are formed so as to cross the gas flow, and the two rear side collision plates 17B adjacent in the gas flow direction are staggered. It is formed to become. In addition, one collision plate 17A on the front side in the gas flow direction is provided between the left and right side walls 11b in front of the second flow path forming wall 16B, and the lower end edge extends below the curved portion 216. For this reason, as shown in FIGS. 5 and 6, the gas flow is meandered left and right between the collision plates 17B, and is collided with the collision plates 17A and 17B while meandering up and down before and after the collision plate 17A. Mainly, oil mist having a large particle size is efficiently separated.

Therefore, the second embodiment has the following effects in addition to the effects of the first embodiment.
(10) In this embodiment, since the collision plates 17 are arranged alternately, the gas flow collides with the collision plate 17 while meandering. Therefore, the collision plate 17 may be a simple flat plate and has a simple configuration. is there.

(Third embodiment)
Next, a third embodiment of the oil separator embodying the present invention will be described.
In this 3rd Embodiment, as shown in FIG.7 and FIG.8, the structure of the upstream side separation part 14 differs from 1st Embodiment. That is, between the inflow port 12 and the drain part 21, the wall part 16 is integrally formed with the bottom wall 11a, the side wall 11b, and the upper wall 11d in the housing 11 so as to close the gas flow path. . A plurality of orifices 16a for increasing the gas flow rate are provided in the center of the wall portion 16 in the width direction. A collision plate 17 as an oil catching portion is integrally provided between the bottom wall 11a and the top wall 11d of the housing 11 so as to face the orifice 16a of the wall portion 16 from the downstream side. A gap 18 </ b> C for forming a gas flow path is formed between both sides of the collision plate 17 and both side walls 11 b of the housing 11. Then, the gas that has passed through each orifice 16 a of the wall portion 16 at a high speed collides with the collision plate 17, whereby oil mist having a large particle size is mainly separated from the gas and captured on the collision plate 17. The captured oil flows down on the bottom wall 11a and is guided to the drain portion 21 through the gap 18C.

In the third embodiment, substantially the same effect as that of the first embodiment can be obtained.
(Fourth embodiment)
Next, a fourth embodiment of an oil separator embodying the present invention will be described.

  In the fourth embodiment, as shown in FIGS. 9 and 10, the weir 27 stands on the bottom wall 23 a in the recess 23 of the housing 11 at a position corresponding to the upstream side of the gas flow of the opening 24 on the wall portion 19. It is installed. A gap 27 a is formed between both side ends of the weir 27 and both side walls of the recess 23. The weir 27 is formed lower than the depth of the recess 23. Therefore, the oil from the oil catcher 20 side reaches the drain portion 21 through the gap 27a. Further, the gas flow including oil from the drain part 21 side is blocked by the weir 27.

Therefore, according to the fourth embodiment, in addition to the effects described in (1) to (9) in the first embodiment, the following effects can be obtained.
(11) The weir 27 prevents the gas flow from moving in the recess 23 toward the outlet 13. Therefore, mixing of the oil in the drain part 21 and the recessed part 23 into the gas flow can be prevented appropriately.

(Fifth embodiment)
Next, a fifth embodiment of the oil separator embodying the present invention will be described.
In the fifth embodiment, the configuration of the third embodiment is changed. As shown in FIG. 11, each orifice of the wall portion 16 is provided on the oil collision surface of the collision plate 17 in the upstream side separation portion 14. A plurality of concave grooves 28 corresponding to 16a are formed to extend in the vertical direction. The gas that has passed through each orifice 16a collides with each concave groove 28 of the collision plate 17 and is captured and separated.

Therefore, in the fifth embodiment, in addition to the effects of the third embodiment, the following effects can be obtained.
(12) Since the plurality of concave grooves 28 are formed on the surface of the wall portion 16 corresponding to each orifice 16a, the oil capturing function is improved.

(Example of change)
The embodiment of the present invention can be modified and embodied as follows.
As shown by the two-dot chain line in FIG. 2, each collision plate 17 is configured to be inclined with respect to the gas flow direction. If comprised in this way, the capture | acquisition function of oil will improve.

  As shown in FIG. 12, a concave portion 26 that is inclined downward toward the drain portion 21 is formed on the bottom portion of the housing 11 on the gas flow upstream side of the drain portion 21. In this way, the oil separated by the upstream separating portion 14 is smoothly guided to the drain portion 21.

  As shown in FIG. 13, inclined portions 23b and 19c that are inclined downward toward the bottom wall 23a are formed on both sides in the width direction of the concave portion 23 and the protruding portion 19b. In this way, the separated oil can be guided into the recess 23 more smoothly. In FIG. 13, a gap 25 is provided between the oil catcher 20 and the upper wall 11d.

The upper plate portion 116 of the second flow path forming wall 16B is formed in parallel with the upper wall 11d of the housing 11.
The lower end of the collision plate 17 of the first embodiment is formed integrally with the upper surface of the upper plate portion 116 of the second flow path forming wall 16B. Alternatively, the lower end of the collision plate 17 is brought into contact with the upper surface of the upper plate portion 116 of the second flow path forming wall 16B.

The concave portion 23, the protruding portion 19 b, and the drain portion 21 are provided at the center in the width direction of the housing 11.
As shown by a two-dot chain line in FIG. 1, the downstream separation portion 15 is displaced to the downstream position of the gas flow, and the wall portion 19 is disposed at a position away from the concave portion 23 to the downstream side of the gas flow.

  DESCRIPTION OF SYMBOLS 11 ... Housing, 11a ... Bottom wall, 12 ... Inlet, 13 ... Outlet, 14 ... Upstream side separation part, 15 ... Downstream side separation part, 17 ... Collision plate, 17A ... Collision plate, 17B ... Collision plate, 19 ... Wall part, 19a ... Orifice, 20 ... Oil capturing body, 21 ... Drain part, 23 ... Recess, 23a ... Bottom wall, 24 ... Opening, 27 ... Weir.

Claims (6)

In the oil separator provided with a plurality of separation portions for separating the oil mist along the gas flow path between the gas inlet and outlet of the housing,
A drain part for returning oil into the engine is provided at the bottom of the housing between the upstream side separation part and the downstream side separation part,
Forming a recess for guiding oil to the drain part at the bottom of the housing between the downstream separating part and the drain part ;
The oil separator according to claim 1, wherein a bottom wall of the concave portion is inclined downward toward the drain portion and is inclined downward in a direction opposite to the gas flow . The oil separator according to claim 1, wherein the concave portion is formed at a position biased laterally in the width direction of the housing . The downstream side separation portion includes a wall portion provided with an orifice for increasing the gas flow rate, and an oil trapping portion facing the downstream side of the orifice,
The oil separator according to claim 1 or 2 , wherein an opening through which oil can be circulated is formed at the lower end portion of the wall portion while the lower end portion is positioned in the recess. The oil separator according to any one of claims 1 to 3, wherein a weir is provided at a bottom portion in the recess. The oil separator according to claim 2, wherein the oil catching portion of the downstream separation portion is made of a filter material. The oil separator according to any one of claims 1 to 5, wherein the upstream separation portion is an impact separation type.

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