Oil Separator

Abstract

To provide an oil separator which achieves high separation efficiency in separation of an oil from a processing object gas containing the mist-like oil.SOLUTION: An oil separator 2 separates an oil from a processing object gas containing the mist-like oil and includes: a body part 20 having a side wall 31 formed into a cylindrical shape extending in a direction of a center axis 20A; a jet part 50 which jets the processing object gas to the interior of the side wall 31 in a circumferential direction; and a vortex flow generating mechanism which suctions the processing object gas to the outer side of the body part 20 and rotates the processing object gas in the circumferential direction to generate vortex flow.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an oil separator. [Background technology]

[0002] 2. Description of the Related Art An oil separator that separates oil mist contained in a gas to be treated from the gas is known (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2009 / 037496 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the oil separator described in Patent Document 1, when the particle size of the oil mist is small, the centrifugal force acting on the oil mist is small, making it difficult to sufficiently separate the oil mist from the gas. Therefore, the separation efficiency of the oil from the gas to be treated that contains the oil mist is low.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide an oil separator that has high separation efficiency for separating oil from a gas to be treated that contains oil mist. [Means for solving the problem]

[0006] In order to solve the above problems, there is provided an oil separator that separates oil from a gas to be treated that contains mist-like oil, the oil separator comprising: a main body portion having a side wall formed in a cylindrical shape extending in the axial direction; an injection portion that injects the gas to be treated in a circumferential direction into the inside of the side wall; and a vortex generating mechanism that sucks the gas to be treated outward from the main body portion and rotates the gas to be treated in the circumferential direction to generate a vortex.

[0007] According to the oil separator described above, the gas to be treated is sucked outward from the main body by the vortex generating mechanism. Specifically, when the gas to be treated is sucked from inside the main body, the gas to be treated rotates in the circumferential direction along the cylindrical side wall, generating a vortex. The vortex generated by the vortex generating mechanism causes the gas to be treated to rotate in the circumferential direction faster than when only the injection section generates a vortex. Then, the oil contained in the gas to be treated is subjected to a stronger centrifugal force. Therefore, more oil is separated from the gas to be treated. Also, oil with small particle size is separated from the gas to be treated. Therefore, the separation efficiency of the oil from the gas to be treated is high. Effect of the Invention

[0008] According to the present invention, the efficiency of separating oil from the gas to be treated that contains oil mist is high. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a closed crankcase ventilation system 1. [Diagram 2] FIG. 2 is a perspective view of the oil separator 2. [Diagram 3] FIG. 2 is a vertical cross-sectional view of the oil separator 2. [Figure 4] 4 is a cross-sectional view taken along the line AA in FIG. [Diagram 5] 2 is a vertical cross-sectional view of an oil separator 2 having a structure 170. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below is subject to various technically preferable limitations for carrying out the present invention, but the scope of the present invention is not limited to the following embodiment and illustrated examples.

[0011] <Outline of Closed Crankcase Ventilation System> FIG. 1 is a schematic diagram of a closed crankcase ventilation system 1 (hereinafter, referred to as the ventilation system 1). The ventilation system 1 includes an oil separator 2, a compressed air passage 3, an exhaust gas passage 4, an oil passage 5, and a breather pipe 6. The oil separator 2 processes blow-by gas (corresponding to the gas to be treated containing mist-like oil) discharged from an engine 7 and separates the oil. The compressed air passage 3 supplies air compressed by a turbocharger 10 to the oil separator 2. The exhaust gas passage 4 supplies the blow-by gas discharged from the engine 7 to the oil separator 2. The oil passage 5 returns the oil separated by the oil separator 2 to the engine 7. The breather pipe 6 returns the processed blow-by gas discharged from the oil separator 2 to an intake-side passage 8 of the engine 7. Specifically, the blow-by gas is returned to a portion of the intake-side passage 8 that connects an air filter 9 and a turbocharger 10. The reduced and treated blow-by gas is mixed with fresh air from an air filter 9 and compressed in a turbocharger 10. It is then cooled in a charge cooler 11 and supplied to the engine 7.

[0012] <Oil separator structure> Fig. 2 is a perspective view of the oil separator 2. Note that Fig. 2 omits illustration of the compressed air passage 3, exhaust gas passage 4, oil passage 5, and breather pipe 6, which are connected to the oil separator 2. The oil separator 2 includes a main body 20, an injection unit 50, an oil drain 60, a structure 70, and a circulation pipe 80. The structure 70 and the circulation pipe 80 correspond to a "vortex generating mechanism."

[0013] (Main body) The main body 20 is a member for applying centrifugal force to the oil by rotating the gas to be treated in the circumferential direction in the internal space, thereby separating the oil from the gas to be treated. The main body 20 is a cylindrical member. The main body 20 has a central axis 20A extending vertically. FIG. 3 is a cross-sectional view of the oil separator 2 in a plane passing through the central axis 20A. Here, the vertical direction is a direction parallel to the central axis 20A. The circumferential direction is a direction around the central axis 20A. The radial direction is a direction perpendicular to the central axis 20A. The main body 20 has an upper body 30 and a lower body 40. The upper body 30 and the lower body 40 are connected in the vertical direction at a joint 21 parallel to the radial direction.

[0014] The upper body 30 has a side wall 31 , a ceiling portion 32 , a protrusion 34 , and a gas exhaust portion 35 . The side wall 31 is a cylindrical member whose axis is the central axis 20A. A substantially circular opening 33 is formed at the lower end of the side wall 31. A protrusion 34 is provided on the outer periphery of the side wall 31 above the lower end of the side wall 31. The protrusion 34 extends in the circumferential direction along the outer periphery of the side wall 31. A ceiling portion 32 is provided at the upper end of the side wall 31. The ceiling portion 32 forms a horizontal, substantially circular surface with the central axis 20A as its axis, and is provided so as to cover the upper part of the side wall 31. The ceiling portion 32 is provided with a gas exhaust portion . The gas discharge part 35 is a substantially cylindrical member extending vertically, and the lower end of the gas discharge part 35 is substantially flush with the lower end of the side wall 31. The gas discharge part 35 is provided penetrating the ceiling part 32 vertically so as to be coaxial with the central axis 20A. An exhaust port 36 is formed at the lower end of the gas discharge part 35. The exhaust port 36 is provided below the injection part 50. A connection port 37 is formed at the upper end of the gas discharge part 35. The gas discharge part 35 communicates the inside and outside spaces of the upper main body 30 (in other words, the inside and outside spaces of the main body 30 communicate with each other). The inside of the gas discharge part 35 communicates with the breather pipe 6 via the connection port 37.

[0015] The lower body 40 has a side wall 41, and a large diameter opening 42 and a small diameter opening 43 formed in the side wall 41. The side wall 41 is a funnel-shaped member that extends vertically and has a substantially circular cross section centered on the central axis 20A. Openings are formed at both the upper and lower ends of the side wall 41, of which the upper large diameter opening is the large diameter opening 42 and the lower small diameter opening is the small diameter opening 43. Therefore, the side wall 41 has a tapered shape that narrows from the large diameter opening 42 toward the small diameter opening 43. The side wall 41 has a protrusion 44 at the large diameter opening 42. The protrusion 44 protrudes from the upper end of the side wall 41 in a radially expanding direction and further protrudes upward. The inner diameter of the protrusion 44 is equal to the outer diameter of the side wall 31 of the upper main body 30. The outer diameter of the protrusion 44 is equal to the outer diameter of the protrusion 34. The vertical length of the protrusion 44 is equal to the distance from the opening 33 of the protrusion 34. The diameter of the large diameter opening 42 is equal to the diameter of the opening 33 of the upper main body 30.

[0016] Here, the coupling portion 21 will be described. The coupling portion 21 has an opening 33 and a large diameter opening 42. are opposed to each other vertically. Since the outer diameter of opening 33 is equal to the inner diameter of protrusion 44, opening 33 is fitted inside protrusion 44. Furthermore, since the vertical length of protrusion 44 is equal to the distance of protrusion 34 from opening 33, no gaps are generated among side wall 31, side wall 41, protrusion 34, and protrusion 44 at coupling portion 21.

[0017] (Injection part) Fig. 4 is a cross-sectional view of the oil separator 2 taken along line AA in Fig. 3. Line AA is the central axis of a first inlet 51 and a nozzle 54, which will be described later. Fig. 4 is a cross-sectional view of the oil separator 2 cut along a horizontal plane passing through line AA. The injection unit 50 has a first inlet 51, a second inlet 52, and an injection pipe 53.

[0018] The first inlet 51 is a member that introduces the air compressed by the turbocharger 10 into the oil separator 2. The first inlet 51 is a substantially cylindrical member with the line AA as its axis. One end of the first inlet 51 is connected to the second inlet 52 and the injection pipe 53. The nozzle 54 is a substantially cylindrical member. The nozzle 54 is fitted into the other end of the first inlet 51 so as to be coaxial with the line AA. The tip of the nozzle 54 on the side fitted into the first inlet 51 is narrowed. The other end of the nozzle 54 is connected to the compressed air flow path 3. The inside of the nozzle 54 communicates with the compressed air flow path 3 via the other end of the nozzle 54.

[0019] The second inlet 52 is a member that introduces the blow-by gas discharged from the engine 7 into the oil separator 2. The second inlet 52 is a substantially cylindrical member. One end of the second inlet 52 is connected to the exhaust gas passage 4. The inside of the second inlet 52 is connected to the exhaust gas passage 4 via the one end of the second inlet 52. The other end of the second inlet 52 is connected to the first inlet 51 and the injection pipe 53. The other end of the second inlet 52 is connected to the first inlet 51 and the injection pipe 53 so as to be perpendicular to the line AA. The inside of the second inlet 52 is connected to the inside of the first inlet 51 and the inside of the injection pipe 53 via the other end of the second inlet 52. The second inlet 52 is provided with a discharge hole 83. The discharge hole 83 is a hole provided in a side wall of the second inlet 52. The discharge hole 83 communicates with the inside and outside spaces of the second inlet 52. The inside of the second inlet 52 communicates with a circulation pipe 80 (described later) via the discharge hole 83.

[0020] The injection pipe 53 is a member that injects compressed air and blow-by gas into the inside of the main body 20. The injection pipe 53 is a substantially cylindrical member. The injection pipe 53 is connected to the first inlet 51 so as to be coaxial with the line AA. The injection pipe 53 is provided so as to horizontally penetrate the side wall 31 of the upper main body 30. The injection pipe 53 is provided so that the line AA, which is the axis, faces the circumferential direction of the upper main body 30. One end of the injection pipe 53 is provided inside the side wall 31 of the upper main body 30 along the side wall 31. The upper part of the injection pipe 53 provided inside the side wall 31 is integrated with the ceiling part 32. The other end of the injection pipe 53 is connected to the first inlet 51 and the second inlet 52 on the outside of the side wall 31. The inside of the injection pipe 53 is communicated with the inside of the first inlet 51 and the inside of the second inlet 52 via the other end of the injection pipe 53.

[0021] (Oil drain) The oil drain 60 is a member that collects oil separated from the blow-by gas inside the main body 20 and guides it to the oil flow path 5. The oil drain 60 has a side wall 61 and a ceiling portion 62. The side wall 61 is a substantially cylindrical member extending vertically. The side wall 61 is provided so as to be coaxial with the central axis 20A. The inner diameter of the side wall 61 is larger than the outer diameter of the small diameter opening 43. A substantially circular opening 63 is provided at the lower end of the side wall 61. The opening 63 is connected to the oil passage 5. The inside of the side wall 61 communicates with the oil passage 5 through the opening 63. The upper end of the side wall 61 is shifted upward from the small diameter opening 43. A ceiling portion 62 is provided at the upper end of the side wall 61. The side wall 61 is provided with a suction hole 82. The suction hole 82 is provided above the small diameter opening 43. The suction hole 82 communicates with the inside of a circulation pipe 80 (described later). The inside of the side wall 61 communicates with the circulation pipe 80 through the suction hole 82. The ceiling portion 62 forms a horizontal, substantially circular surface centered on the central axis 20A, and is provided so as to cover an upper portion of the side wall 61. Since the ceiling portion 62 is offset upward from the small diameter opening portion 43, the side wall 41 penetrates the ceiling portion 62 in the vertical direction.

[0022] (structure) The structure 70 is one of the vortex generating mechanisms. The structure 70 is a member that generates a vortex inside the main body 20. The structure 70 has a core rod 71, a flange 72, and a flow path 73. The core rod 71 is a rod-shaped member that extends vertically. The core rod 71 is provided inside the side wall 41 and above the small diameter opening 43. The core rod 71 is provided so as to be coaxial with the central axis 20A. A flange 72 is provided on the outer periphery of the core rod 71. The flange 72 is a plate-like member. The flange 72 is provided along the outer periphery of the core rod 71 in a left-handed spiral shape as viewed from above, with the core rod 71 as the center. The outer shape of the flange 72 is tapered downward. The gradient of the tapered shape of the flange 72 is equal to the gradient of the tapered shape of the side wall 41. Therefore, the flange 72 is fitted along the inside of the side wall 41. In detail, the flange 72 is fixed to the inside of the connecting portion between the ceiling portion 62 and the side wall 41 (FIG. 3). The flow path 73 is a spiral hole formed by the core rod 71, the flange 72, and the side wall 41. The flow path 73 is formed by the side wall 41 closing a gap formed by the flanges 72 facing each other at a distance from each other above and below, along the outer shape of the flanges 72. In this embodiment, the flow path 73 is a left-handed spiral that progresses counterclockwise downward when viewed from above.

[0023] (circulation tube) The circulation pipe 80 is one of the vortex generating mechanisms. The circulation pipe 80 is a member that generates a vortex inside the main body 20 and generates a negative pressure inside the oil drain 60. The circulation pipe 80 has a pipe portion 81. The pipe portion 81 is a member having a substantially circular pipe shape. In this embodiment, the pipe portion 81 is provided from the side wall 61 to the side wall of the second inlet 52. One end of the pipe portion 81 is connected to the side wall 61. A circular suction hole 82 is formed in one end of the pipe portion 81. The suction hole 82 penetrates the side wall 61. The inside of the pipe portion 81 communicates with the inside of the side wall 61 through the suction hole 82. One end of the pipe portion 81 extends from a connecting portion with the side wall 61 in parallel to a tangent to the side wall 61 when viewed from above and in a counterclockwise direction. It is desirable to provide the connecting portion between the pipe portion 81 and the side wall 61 and the suction hole 82 as far away as possible from the central axis 20A. The other end of the pipe portion 81 is connected to the side wall of the second inlet 52. A circular discharge hole 83 is formed in the other end of the pipe portion 81. The discharge hole 83 penetrates the side wall of the second inlet 52. The inside of the pipe portion 81 communicates with the inside of the second inlet 52 through the discharge hole 83. In other words, the inside of the second inlet 52 communicates with the inside of the side wall 61 through the pipe portion 81.

[0024] <Oil separator operation> Next, separation of oil from blow-by gas in the oil separator 2 will be described.

[0025] Blow-by gas is supplied from the engine 7 to the second inlet 52 through the exhaust gas passage 4. Air compressed by the turbocharger 10 is supplied to the nozzle 54 through the compressed air passage 3. The compressed air is injected from the nozzle 54 and flows into the injection pipe 53 through the first inlet 51. The compressed air is injected from the nozzle 54 at high speed, generating a low-pressure space inside the first inlet 51. Therefore, the blow-by gas is sucked from the second inlet 52 through the first inlet 51 into the injection pipe 53. Then, the blow-by gas is mixed with the compressed air in the injection pipe 53. The mixed blow-by gas and compressed air (hereinafter referred to as the gas to be treated) is injected from the injection pipe 53 in the circumferential direction toward the side wall 31. The dashed arrows in FIG. 3 and FIG. 4 indicate the direction in which the gas to be treated moves.

[0026] The gas to be treated injected from the injection pipe 53 moves along the inner side of the sidewall 31, that is, while rotating in the circumferential direction. In this embodiment, the gas to be treated moves along the inner side of the sidewall 31 while rotating counterclockwise when viewed from above. Since the upper part of the injection pipe 53 is integrated with the ceiling part 32, the gas to be treated moves downward so as to pass below the injection pipe 53. The gas to be treated moves along the inner side of the sidewall 31 while rotating counterclockwise when viewed from above. In other words, when the gas to be treated is injected from the injection pipe 53, it moves downward in a vortex flow close to a spiral shape.

[0027] When the gas to be treated reaches the lower end of the side wall 31, it moves along the side wall 41. Since the side wall 41 has a tapered shape narrowing downward, the gas to be treated moves as a spiral vortex whose diameter gradually decreases downward.

[0028] Since the gas to be treated moves along the side wall 31 and the side wall 41, the trajectory along which the gas to be treated moves is circular when viewed from above. Therefore, the oil contained in the gas to be treated is subjected to centrifugal force (a force directed radially outward). The oil subjected to centrifugal force gradually moves radially outward while moving on the vortex current. Then, when the oil comes into contact with the side wall 31 or the side wall 41, the oil is separated from the gas to be treated. The separated oil moves downward along the side wall 31 or the side wall 41 under the force of gravity. The separated oil eventually reaches the oil drain 60.

[0029] When the separated oil reaches the oil drain 60, it flows through the opening 63 into the oil passage 5. The separated oil passes through the oil passage 5 and is returned to the engine 7.

[0030] As described above, the compressed air is injected from the nozzle 54 toward the injection pipe 53, so that the blow-by gas in the second inlet 52 is sucked into the first inlet 51. At this time, the gas inside the pipe portion 81, which is in communication with the second inlet 52 through the discharge hole 83, is sucked into the second inlet 52. Then, the gas inside the oil drain 60, which is in communication with the pipe portion 81 through the suction hole 82, is sucked into the pipe portion 81. Then, the gas inside the side wall 41, which is in communication with the inside of the oil drain 60 through the small diameter opening 43, is sucked into the inside of the oil drain 60. Here, the gas inside the side wall 41 is the gas to be treated that is injected from the injection pipe 53. That is, a part of the gas to be treated inside the side wall 41 is sucked into the second inlet 52 from inside the side wall 41 through the inside of the oil drain 60 and the pipe portion 81. The sucked gas to be treated is sucked into the injection pipe 53 from the second inlet 52 through the first inlet 51, like the blow-by gas. The sucked gas to be treated is mixed with the compressed air and blow-by gas in the injection pipe 53 and is injected again toward the side wall 31 .

[0031] The gas to be treated that is drawn from inside the side wall 41 into the oil drain 60 passes through the structure 70. At this time, the gas to be treated moves downward inside the side wall 41, and when it reaches the upper part of the structure 70, it is drawn into the flow path 73. Since the flow path 73 has a spiral shape, the gas to be treated passes through the flow path 73 as a spiral vortex. Then, the gas to be treated reaches the inside of the oil drain 60. At this time, since the gas to be treated is drawn through the flow path 73, the vortex generated in the flow path 73 extends to the inside of the side wall 41. That is, the flow path 73 generates a vortex inside the side wall 41. In this embodiment, since the flow path 73 is a left-handed spiral that proceeds counterclockwise when viewed from above, the vortex generated by the flow path 73 is counterclockwise when viewed from above.

[0032] Furthermore, due to the effect of the negative pressure generated by the pipe portion 81 through the suction hole 82, the gas to be treated also generates a counterclockwise vortex flow as viewed from above inside the oil drain 60.

[0033] The vortex generated by the flow path 73 and the pipe section 81 is different from the vortex generated by the injection pipe 53 injecting the target gas toward the side wall 31. Here, the direction of the vortex generated by the flow path 73 and the vortex generated by the injection pipe 53 is both counterclockwise as viewed from above. Therefore, the vortex generated by the flow path 73 strengthens the vortex inside the main body section 20. Then, the target gas inside the main body section 20 moves counterclockwise inside the main body section 20 as viewed from above due to the strengthened vortex. At this time, since the vortex is strengthened, the centrifugal force that the oil contained in the target gas receives is strengthened. Therefore, more oil reaches the side wall 31 and the side wall 41 and is separated from the target gas.

[0034] The oil is separated from the gas to be treated, and the gas to be treated is purified. The purified gas to be treated escapes upward from the inside of the side wall 41 and flows to the gas discharge section 35. The purified gas to be treated then flows from the gas discharge section 35 through the connection port 37 to the breather pipe 6. The purified gas to be treated flows through the breather pipe 6 to the intake side flow path 8. The purified gas to be treated that has flowed to the intake side flow path 8 is mixed with fresh air that flows from the air filter 9 to the intake side flow path 8, and is compressed by the turbocharger 10.

[0035] <Effects> In the above embodiment, the oil separator 2 separates oil from the gas to be treated which contains mist-like oil, and is equipped with a main body 20 having side walls 31 and 41 formed in a cylindrical shape extending in the direction of the central axis 20A, an injection section 50 which injects the gas to be treated in a circumferential direction into the inside of the side wall 31, and a vortex generating mechanism which sucks the gas to be treated outward from the main body 20 and rotates the gas to be treated in the circumferential direction to generate a vortex.

[0036] According to such an oil separator 2, the gas to be treated is sucked outward from the main body 20 by the vortex generating mechanism. The gas to be treated is rotated in the circumferential direction inside the main body 20 by the vortex generating mechanism, and a vortex is generated inside the main body 20. As a result, a stronger vortex is generated inside the main body 20, and the gas to be treated rotates in the circumferential direction faster than when only the injection unit 50 generates a vortex inside the main body 20. Then, the oil contained in the gas to be treated is subjected to a stronger centrifugal force. As a result, more oil is separated from the gas to be treated. Also, oil with smaller particle size is separated from the gas to be treated. In other words, an oil separator with high separation efficiency for separating the oil mist from the gas to be treated that contains the oil mist can be provided.

[0037] In addition, the vortex generating mechanism of the oil separator 2 according to this embodiment is provided with a circulation pipe 80 that draws in the gas to be treated and supplies it to the injection unit 50.

[0038] By providing the circulation pipe 80, the gas to be treated is sucked from inside the main body 20 and supplied to the spraying part 50. The gas to be treated is sprayed from the spraying part 50 back into the main body 20, so that the gas to be treated circulates between the main body 20 and the spraying part 50. As a result, the oil separation process is repeatedly performed on the gas to be treated. In other words, the efficiency of separating the oil mist from the gas to be treated is increased.

[0039] In addition, the vortex generating mechanism of the oil separator 2 in this embodiment further includes a structure 70 in which a spiral flow passage 73 having a central axis extending in the direction of the central axis 20A is formed, and a vortex is generated by passing the gas to be treated through the flow passage 73.

[0040] By providing the structure 70, the gas to be treated passes through the spiral flow path 73. Then, a vortex is generated inside the main body 20 by the gas to be treated that has passed through the flow path 73. As a result, a stronger vortex is generated inside the main body 20, and the gas to be treated rotates faster in the circumferential direction, compared to a case in which only the injection unit 50 generates a vortex inside the main body 20. Then, the oil contained in the gas to be treated is subjected to a stronger centrifugal force. In other words, the efficiency of separating the oil mist from the gas to be treated is increased.

[0041] In addition, the oil separator 2 of this embodiment is provided with an oil drain 60 that is connected to one end of the main body 20 in the direction of the central axis 20A and discharges the separated oil to the outside of the main body 20, and the suction hole 82 of the circulation pipe 80 is arranged in the oil drain 60.

[0042] By arranging the suction hole 82 of the circulation pipe 80 in the oil drain 60, the circulation pipe 80 sucks the gas to be treated from inside the oil drain 60. The gas to be treated is then sucked up to the lower end of the main body 20, passes through the oil drain 60, and is sucked into the circulation pipe 80 from the suction hole 82. Since the distance over which the gas to be treated is sucked becomes longer, the frequency of oil separation processing performed on the gas to be treated increases. In other words, the efficiency of separating the oil mist from the gas to be treated increases.

[0043] In addition, the oil separator 2 of this embodiment is provided with an oil drain 60 that is connected to one end of the main body 20 in the direction of the central axis 20A and discharges the separated oil to the outside of the main body 20, and a structure 70 is arranged at the connection between the oil drain 60 and the main body 20.

[0044] By disposing the structure 70 at the connection between the oil drain 60 and the main body 20, the gas to be treated always passes through the flow path 73 of the structure 70 when moving from inside the main body 20 to the oil drain 60. Then, the gas to be treated flows reliably through the flow path 73, so that the structure 70 generates a vortex inside the main body 20 more frequently. As a result, a stronger vortex is generated inside the main body 20 compared to the case where only the injection part 50 generates a vortex inside the main body 20, and the gas to be treated rotates faster in the circumferential direction. Then, the oil contained in the gas to be treated is subjected to a stronger centrifugal force. In other words, the efficiency of separating the oil mist from the gas to be treated is increased.

[0045] Moreover, the injection section 50 of the oil separator 2 according to this embodiment injects the high-pressure fluid, and also sucks in the gas to be treated and injects the gas to be treated.

[0046] When the injection unit 50 injects the high-pressure fluid, the gas to be treated is sucked into the injection unit 50. Then, the gas to be treated is mixed with the high-pressure fluid in the injection unit 50 and accelerates. When the speed at which the gas to be treated is injected from the injection unit 50 increases, the gas to be treated rotates faster in the circumferential direction. As a result, a stronger vortex is generated inside the main body 20 compared to when the injection unit 50 injects the gas to be treated alone. Then, the oil contained in the gas to be treated is subjected to a stronger centrifugal force. In other words, the efficiency of separating the oil mist from the gas to be treated is increased.

[0047] <Modification> The modifications described below may be applied in combination.

[0048] (1) Variation 1 A propeller-shaped structure 170 may be provided instead of the structure 70. Fig. 5 is a cross-sectional view of the oil separator 2 provided with the structure 170. The structure 170 has a core material 171 and a plurality of blades 172. The core material 171 is a cylindrical member. The core material 171 is provided inside the side wall 41 so as to be coaxial with the central axis 20A. The position where the core material 171 is provided is above the small diameter opening 43. A plurality of blades 172 are provided on the outer periphery of the core material 171. The blades 172 are plate-shaped members that extend radially outward from the outer periphery of the core material 171. The blades 172 are provided in a spiral shape along the outer periphery of the core material 171. Therefore, a spiral flow path 173 is formed along the outer periphery of the core material 171 between two adjacent blades 172. In this embodiment, five blades 172 are provided for the core material 171. Therefore, five flow paths 173 are provided for the core material 171. In this embodiment, the flow path 173 is a left-handed spiral that proceeds counterclockwise downward when viewed from above. The outer shape of the blades 172 is tapered downward. The gradient of the tapered shape of the blades 172 is equal to the gradient of the tapered shape of the side wall 41. Therefore, the blades 172 are fitted along the inside of the side wall 41. Specifically, the vanes 172 are fixed to the inside of the connection portion between the ceiling portion 62 and the side wall 41 (FIG. 5).

[0049] When the gas to be treated is sucked from inside the side wall 41 downwards in the structure 170, the gas to be treated passes through a plurality of flow paths 173 formed between a plurality of blades 172. Since the flow paths 173 are spiral-shaped, the gas to be treated passes through the flow paths 173 as a spiral vortex. Then, the gas to be treated reaches the oil drain 60. At this time, since the gas to be treated is sucked through the flow paths 173, the vortex generated in the flow paths 173 extends to the inside of the side wall 41. That is, the flow paths 173 generate a vortex inside the side wall 41. In this embodiment, five flow paths 173 are provided in the structure 170. Therefore, the flow paths 173 generate a vortex in a counterclockwise direction as viewed from above. The vortex generated by the flow paths 173 strengthens the vortex of the gas to be treated inside the main body 20.

[0050] (2) Variation 2 The structure 70 does not have to be provided. In this case, the gas to be treated is sucked from the main body 20 by the circulation pipe 80. Then, a vortex is generated in the main body 20 as the circulation pipe 80 sucks the gas to be treated.

[0051] (3) Variation 3 The oil drain 60 does not have to be provided. In this case, the oil flow path 5 is connected to the small diameter opening 43. Also, the suction hole 82 is provided in the side wall 41 of the lower body 40. Therefore, the inside of the lower body 40 communicates with the circulation pipe 80 via the suction hole 82.

[0052] (4) Variation 4 The injection unit 50 does not have to inject high-pressure fluid. In this case, the nozzle 54 is removed from the first inlet 51. Also, the compressed air passage 3 is connected to one end of the first inlet 51. Compressed air is supplied from the first inlet 51 to the injection pipe 53. Blow-by gas is supplied from the second inlet 52 to the injection pipe 53. The compressed air and the blow-by gas are mixed in the injection pipe 53 to become the gas to be treated. The gas to be treated is injected from the injection pipe 53 in a circumferential direction toward the side wall 31. When the circulation pipe 80 is connected to the second inlet 52, a part of the gas to be treated is sucked from inside the main body 20 and supplied to the second inlet 52. The part of the gas to be treated that has been supplied is supplied from the second inlet 52 to the injection pipe 53, where it is mixed with the compressed air and blow-by gas. [Explanation of symbols]

[0053] 2. Oil separator 20…Main body 30…Upper body (main body) 31…Side wall 40…Lower body (main body) 41...Side wall 50…Injection part 60…Oil drain 70...Structure (vortex generation mechanism) 73...Flow path 80…Circulation pipe (vortex generation mechanism) 82…Suction hole

Claims

1. An oil separator for separating oil from a gas to be treated that contains an oil mist, A main body portion having a side wall formed in a cylindrical shape extending in an axial direction; an injection unit that injects the gas to be treated in a circumferential direction into the side wall; a vortex generating mechanism that sucks the gas to be treated outward from the main body and rotates the gas to be treated in the circumferential direction to generate a vortex, the vortex generating mechanism further includes a structure in which a spiral flow passage having a central axis extending in the axial direction is formed, and the vortex generating mechanism generates the vortex by passing the gas to be treated through the flow passage; an oil drain connected to one end of the body in the axial direction and configured to discharge the separated oil to the outside of the body; The structure is disposed at a connection portion between the oil drain and the main body. Oil separator.

2. The oil separator according to claim 1 , wherein the vortex generating mechanism includes a circulation section that draws in the gas to be treated and supplies it to the injection section.

3. The circulation section has a suction hole for sucking the target gas from the oil drain, The oil separator according to claim 2 .

4. The oil separator according to claim 1 , wherein the injector injects a high-pressure fluid while sucking in the gas to be treated and injecting the gas to be treated.

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