Oil separator

Abstract

To provide an oil separator having high efficiency of separating oil from gas to be processed containing mist-like oil.SOLUTION: An oil separator that separates oil from gas containing mist-like oil comprises: a housing which has a cylindrically formed sidewall extending in an axial direction, and in which a first space inside the sidewall and a second space outside the sidewall are formed, and which has a partition wall in which a communication hole allowing the first space and the second space to communicate with each other is formed and which forms a boundary between the first space and the second space; an injection part which is connected to the housing, injects the gas into the first space in a circumferential direction of the sidewall, and rotates the gas in the circumferential direction in the axial direction view; a valve element which is provided for the communication hole to open / close a flow channel communicating the first space and the second space, and increases an aperture of the flow channel as the pressure inside the first space to the pressure inside the second space becomes higher; and a collector which is arranged opposing the flow channel, has permeability, and collects the oil.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] An oil separator that separates mist-like oil contained in a gas to be processed from the gas is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the oil separator described in Patent Document 1 has a low separation efficiency, which is the efficiency of separating oil from the gas to be processed containing mist-like oil.

[0005] Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide an oil separator having high separation efficiency.

Means for Solving the Problems

[0006] In order to solve the above problems, in one aspect, there is provided a housing having a side wall formed in a cylindrical shape extending in the axial direction, with a first space inside the side wall and a second space outside the side wall formed therein, the housing having a partition wall that forms a boundary between the first space and the second space and has a communication hole formed therethrough to communicate the first space and the second space, an injection portion connected to the housing for injecting the gas in the circumferential direction of the side wall into the first space and rotating the gas in the circumferential direction in the axial view, a valve body provided in the communication hole for opening and closing a flow path that communicates the first space and the second space and increasing the opening degree of the flow path as the pressure in the first space is higher than the pressure in the second space, and a trapping body disposed opposite to the flow path and having air permeability for trapping the oil. An oil separator is provided that includes these components.

Advantages of the Invention

[0007] According to the present invention, the efficiency of separating oil from the gas to be processed containing mist-like oil is high.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, although various technically preferable limitations are imposed on the embodiments described below for carrying out the present invention, the scope of the present invention is not limited to the following embodiments and illustrated examples.

[0010] <Overview of Closed Crankcase Ventilation System> FIG. 1 is a schematic diagram of a closed crankcase ventilation system 1 (hereinafter referred to as ventilation system 1). The ventilation system 1 includes an oil separator 2, a compressed air flow path 3, an exhaust gas flow path 4, an oil flow path 5, and a breather pipe 6. The oil separator 2 processes blow-by gas (containing mist-like oil) discharged from the engine 7 and separates the oil. The compressed air flow path 3 supplies the air compressed by the turbocharger 10 to the oil separator 2. The exhaust gas flow path 4 supplies the blow-by gas discharged from the engine 7 to the oil separator 2. The oil flow path 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 the intake side flow path 8 of the engine 7. Specifically, it is returned to the portion connecting the air filter 9 and the turbocharger 10 in the intake side flow path 8. The returned processed blow-by gas is mixed with fresh air from the air filter 9 and compressed by the turbocharger 10. Thereafter, it is cooled by the charge cooler 11 and supplied to the engine 7.

[0011] <Structure of Oil Separator> FIG. 2 is a perspective view of the oil separator 2. Note that FIG. 2 omits the illustration of the compressed air flow path 3, the exhaust gas flow path 4, the oil flow path 5, and the breather pipe 6 connected to the oil separator 2, and shows the direction of fluid flow with white arrows. The oil separator 2 includes a main body portion 20, an injection portion 50, an oil drain 60, a valve 70, a trapping body 80, and a holding member 90.

[0012] (Main Body Portion) The main body part 20 is a member for separating oil from the gas to be processed. The main body part 20 is a substantially cylindrical member. The main body part 20 has a central axis 20A extending vertically. FIGS. 3 to 5 are cross-sectional views of the oil separator 2 in a plane passing through the central axis 20A. Here, the vertical direction is the direction parallel to the central axis 20A. The circumferential direction is the direction around the central axis 20A as shown in FIG. 8. The radial direction is the direction orthogonal to the central axis 20A (FIG. 8). The main body part 20 has an upper main body 30 disposed on the upper side and a lower main body 40 disposed on the lower side. The upper main body 30 and the lower main body 40 are connected vertically at a connecting part 21 parallel to the radial direction.

[0013] The upper main body 30 has a side wall 31, a ceiling part 32, an outer side wall 34, a gas discharge part 35, a lid part 38, and a discharge cylinder 39.

[0014] The side wall 31 is a substantially cylindrical member with the central axis 20A as the axis. At the lower end of the side wall 31, a substantially circular opening 33 is formed in a vertical view.

[0015] An outer side wall 34 is provided outside the side wall 31 in the radial direction with a space therebetween. The outer side wall 34 extends in the circumferential direction along the outer periphery of the side wall 31, and its lower end is connected to the oil drain 60. An induction path S4 for guiding oil to the oil drain 60 is formed between the side wall 31 and the outer side wall 34.

[0016] The ceiling part 32 forms a horizontal substantially circular surface with the central axis 20A as the axis and is provided to cover the upper part of the side wall 31. A gas discharge part 35 is provided in the ceiling part 32.

[0017] The gas discharge part 35 is a substantially cylindrical member extending vertically and is provided to penetrate the ceiling part 32 vertically so as to be coaxial with the central axis 20A. The lower end of the gas discharge part 35 is substantially flush with the lower end of the side wall 31.

[0018] At the lower end of the gas discharge part 35, a discharge port 36 is formed. The discharge port 36 is provided below the injection part 50. By setting the discharge port 36 below the ceiling part 32 and the injection part 50, the discharge of the processing target gas in which oil has not been separated is prevented.

[0019] The upper part of the gas discharge part 35 forms a connection part 37. The connection part 37 is a cylindrical member protruding upward from the ceiling part 32, and forms a circular opening 37B when viewed from above. At the upper part of the connection part 37, notch parts 37A formed by being notched downward from the uppermost end are provided at intervals of 180 degrees in the circumferential direction. The notch parts 37A respectively form a flow path for the processing target gas with the valve 70 placed on the upper end of the connection part 37.

[0020] Via the gas discharge part 35, the first space S1 below the ceiling part 32 and the second space S2 (described later) above are connected (hereinafter, the connection of spaces is also referred to as "communicating"). In other words, the gas discharge part 35 forms a communication hole that communicates the upper and lower parts of the ceiling part 32. The first space S1 is a space formed inside the side walls 31 and 41.

[0021] The lid part 38 is a housing arranged to cover the upper parts of the ceiling part 32 and the gas discharge part 35, and is connected to the side wall extending upward from the side wall 31 and the upper end part of the outer side wall 34. Below the lid part 38, a second space S2 is formed between the lid part 38 and the ceiling part 32.

[0022] The discharge cylinder 39 is a cylindrical member provided so as to protrude radially outward from the lid part 38. The end part in the radially outer direction of the discharge cylinder 39 is connected to the breather pipe 6, and the processed gas flows through the inside of the discharge cylinder 39 to the breather pipe 6.

[0023] The lower body 40 has a side wall 41, 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 extending vertically with 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. Among them, 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.

[0024] Inside the side wall 41, a groove portion 41A is provided which is formed so as to be recessed from the inner peripheral surface of the side wall 41. The groove portion 41A extends vertically from the upper part of the side wall 41 to the small-diameter opening 43. A plurality of groove portions 41A are formed at regular intervals in the circumferential direction.

[0025] Here, the coupling portion 21 will be described. At the coupling portion 21, the opening 33 and the large-diameter opening 42 face each other vertically. Since the outer diameter of the opening 33 is equal to the outer diameter of the large-diameter opening 42, the side wall 31 and the side wall 41 fit together without a gap.

[0026] (Valve) The valve 70 is a valve that adjusts the flow rate of the gas to be processed flowing from the first space S1. As shown in FIGS. 3 to 5, the valve 70 has a valve body 71, a valve elastic body 72, a cylindrical portion 73, and a spring 74.

[0027] The valve body 71 is a member that forms a part of a valve body that opens and closes the flow path of the gas to be processed with the connection portion 37. The valve body 71 is a disk-shaped member formed in a substantially circular shape when viewed vertically, and is arranged so as to cover the connection portion 37 and the opening 37B from above.

[0028] The valve elastic body 72 is an annular member arranged to be in contact with substantially the entire circumference (excluding the notch portion 37A) of the upper end portion of the connection portion 37. The valve elastic body 72 is provided along the outer peripheral edge of the lower surface of the valve body 71 and can move up and down together with the valve body 71. The valve elastic body 72 is formed of a material having elasticity such as an elastomer.

[0029] When the valve body 71 moves downward, the valve elastic body 72 comes into contact with the upper end portion of the connection portion 37. Further, when the valve body 71 moves upward, the valve elastic body 72 moves upward away from the upper end portion of the connection portion 37 and forms an annular gap between the valve elastic body 72 and the upper end portion of the connection portion 37. This gap is a flow path for the gas to be processed flowing from the first space S1 to the second space S2, and its size changes depending on the vertical positions of the valve body 71 and the valve elastic body 72.

[0030] The cylindrical portion 73 is a part that lowers the center of gravity position of the valve 70 and makes it difficult for the valve 70 to tilt with respect to the connection portion 37 (that is, the main body portion 20) when a non-uniform force acts on the valve 70. The cylindrical portion 73 is a cylindrical member extending vertically. The cylindrical portion 73 is provided so as to protrude downward from the lower surface of the valve body 71. In the present embodiment, the cylindrical portion 73 is located in the first space S1. Note that the cylindrical portion 73 may not be provided on the valve body 71.

[0031] Two holes 70A are formed in the valve body 71 and the cylindrical portion 73 at intervals of 180 degrees in the circumferential direction (FIG. 5). The holes 70A form a flow path for allowing the gas to be processed in the first space S1 to flow out to the second space S2 regardless of the open / closed state of the valve 70. The holes 70A are holes that communicate the space outside the valve body 71 with the internal space of the cylindrical portion 73. The holes 70A are provided so as to penetrate in the radial direction from the outer peripheral surface of the valve body 71 to the inner peripheral surface of the cylindrical portion 73. The gas to be processed flowing into the inside of the cylindrical portion 73 can flow out to the second space S2 through the holes 70A. The size of the holes 70A does not change depending on the flow rate of the gas to be processed flowing into the internal space of the cylindrical portion 73. That is, the holes 70A form a flow path with a constant opening degree. Note that it is also possible to configure the valve 70 not to be provided with the holes 70A (flow paths).

[0032] The spring 74 supports the valve body 71 in a vertically movable state. The spring 74 is a coil spring. The upper end portion of the spring 74 is connected to the lid portion 38, and the lower end portion is connected to the upper surface of the valve body 71. The spring 74 is sandwiched between the upper surface of the valve body 71 and the lower surface of the lid portion 38, and biases the valve body 71 downward by its own biasing force.

[0033] The vertical positions of the valve body 71 and the valve elastic body 72 with respect to the connecting portion 37 are determined by the pressure difference between the first space S1 and the second space S2. When the pressure in the first space S1 is greater than the set value with respect to the pressure in the second space, the valve body 71 and the valve elastic body 72 move upward against the biasing force of the spring 74, form a gap with the connecting portion 37, and open the opening 37B to serve as a flow path for the gas to be processed. The greater the pressure in the first space S1 is with respect to the pressure in the second space, the higher the valve body 71 and the valve elastic body 72 are positioned, forming a large gap, that is, a flow path.

[0034] On the other hand, when the pressure in the first space S1 is equal to or less than a set value with respect to the pressure in the second space, the valve elastic body 72 maintains a state of contact with the connection portion 37. In this way, the valve body 71 and the valve elastic body 72 can change the opening degree of the flow path of the gas to be processed.

[0035] Note that the size of the flow path formed by the notch portion 37A and the hole 70A is constant and does not depend on the pressure in either the first space S1 or the second space S2.

[0036] As described above, flow paths that communicate the first space S1 and the second space S2 are formed by the flow path due to the gap (hereinafter also referred to as "gap flow path") between the valve elastic body 72 and the connection portion 37, the flow path due to the notch portion 37A, and the flow path due to the hole 70A. Regarding these three flow paths, in any of the flow paths, the gas to be processed flows into the flow path from the first space S1 side and flows out to the second space S2 side. That is, the outlet of the flow path is formed on the outer peripheral portion of the valve body 71, the outer peripheral portion of the valve elastic body 72, or the outer peripheral portion of the connection portion 37. The inlet of the flow path is formed on the inner peripheral portion of the cylindrical portion 73 or the inner peripheral portion of the connection portion 37.

[0037] (Trapping body) The trapping body 80 is a member that has air permeability and separates mist-like oil from the gas to be processed. The trapping body 80 is, for example, a non-woven fabric. The trapping body 80 is arranged so as to surround the radially outer sides of the valve body 71, the valve elastic body 72, and the connection portion 37 in a circular shape when viewed from above. Therefore, the trapping body 80 faces the outlets of the respective flow paths with respect to the gap flow path between the valve elastic body 72 and the connection portion 37, the flow path due to the notch portion 37A, and the flow path due to the hole 70A in the radial direction.

[0038] (Holding member) The holding member 90 is a member for holding the trapping body 80. In the present embodiment, the holding member 90 holds the trapping body 80 by sandwiching it from the outer side and the inner side in the radial direction. The holding member 90 is a member that supports the trapping body 80 from the outer side and the inner side in the radial direction. The holding member 90 is a rod-shaped member formed so as to protrude upward from the upper surface of the ceiling portion 32. A plurality of holding members 90 are provided at intervals in the circumferential direction along the inner circumference and the outer circumference of the trapping body 80. The number of the holding members 90 is not particularly limited as long as the trapping body 80 can be supported from the inside and the outside in the radial direction.

[0039] (Injection section) As shown in FIGS. 2 to 8, the injection section 50 has an inlet 51, an injection pipe 53, and a nozzle 54.

[0040] The inlet 51 is a member for introducing the air compressed by the turbocharger 10 into the oil separator 2. The inlet 51 is a substantially cylindrical member. The inlet 51 is connected to the upper body 30 and extends in the tangential direction of the side wall 31 in a top view (FIG. 8). The inlet 51 has one end connected to the injection pipe 53 and the other end protruding outward of the main body portion 20.

[0041] The inlet 51 is also a member for introducing the blow-by gas discharged from the engine 7 into the oil separator 2 via the oil drain 60. An opening 51A is formed at the lower part of the inlet 51 to communicate the inside of the oil drain 60 (a third space S3 described later) with the inside of the inlet 51.

[0042] The nozzle 54 is a substantially cylindrical member. The nozzle 54 is fitted into the other end of the inlet 51 so as to be coaxial with the inlet 51. The tip end portion of the nozzle 54 on the side fitted into the inlet 51 is thinner. The outer end portion of the nozzle 54 is connected to the compressed air flow path 3, and therefore, the inside of the nozzle 54 communicates with the compressed air flow path 3.

[0043] The injection pipe 53 is a substantially cylindrical member that injects compressed air and blow-by gas into the interior of the main body 20. The injection pipe 53 is provided so as to horizontally penetrate the side wall 31 of the upper main body 30. Further, the injection pipe 53 is connected to the inlet 51 so as to be coaxial with the inlet 51 and the nozzle 54. The injection pipe 53 communicates the interior of the inlet 51 and the first space S1.

[0044] (Oil drain) The oil drain 60 is a member that collects the oil separated from the gas to be processed inside the main body 20 and guides it to the oil flow path 5, and is also a member that introduces the blow-by gas discharged from the engine 7.

[0045] The oil drain 60 is provided so as to cover the lower part of the lower main body 40 and has a side wall 61, a bottom plate 62, an introduction cylinder 63 connected to the exhaust gas flow path 4, a guide cylinder 64, and a check valve 65. A third space S3 is formed inside the oil drain 60. Specifically, the third space S3 is a space formed between the side wall 61 and the bottom plate 62 and the lower main body 40.

[0046] The side wall 61 is a substantially cylindrical member extending vertically. The side wall 61 is provided so as to be substantially coaxial with the central axis 20A, and its upper end is connected to the upper main body 30 and the injection part 50 without a gap. The inner diameter of the side wall 61 is larger than the outer diameter of the small-diameter opening 43, and the oil discharged from the small-diameter opening 43 can be guided to the oil flow path 5 without leaking to the outside.

[0047] The bottom plate 62 is connected to the lower end of the side wall 61. The bottom plate 62 is a substantially disc-shaped member in top view, and a substantially circular opening 62A is formed in the central part. The upper surface of the bottom plate 62 is provided with a gradient that slopes downward toward the opening 62A, and the oil can be guided to the opening 62A.

[0048] The third space S3 communicates with the oil flow path 5 via the opening 62A. Therefore, the oil in the oil drain 60 flows into the oil flow path 5 through the opening 62A as indicated by the white arrow in FIG. 5.

[0049] The introduction cylinder 63 is a substantially cylindrical member that extends horizontally and is provided so as to protrude radially outward from the side wall 61. Since the radially outer end of the introduction cylinder 63 is connected to the exhaust gas flow path 4, the blow-by gas is introduced from the exhaust gas flow path 4 into the third space S3 through the inside of the introduction cylinder 63.

[0050] Above the introduction cylinder 63, an opening 51A is formed between the side wall 61 and the lower body 40. The third space S3 and the inside of the inlet 51 communicate with each other through the opening 51A.

[0051] The guide cylinder 64 has a hollow cylindrical portion 641 that is located below the guide path S4 and extends in the vertical direction, and a plate portion 642 that is fixed to the lower portion of the cylindrical portion 641 and extends in the radial direction.

[0052] The cylindrical portion 641 is disposed between the side wall 61 and the side wall 41, and a part thereof is connected to the side wall 41 and the side wall 61. The inside of the cylindrical portion 641 forms a guide path S5 that communicates with the guide path S4, and the oil flowing through the guide path S4 can be guided to the third space S3.

[0053] The plate portion 642 is formed with an opening 64A that penetrates the plate portion 642 vertically and a through hole 64B that is provided at the center of the plate portion 642 and penetrates the plate portion 642 vertically.

[0054] The check valve 65 is a valve that opens and closes the opening 64A. The check valve 65 has a valve body 651, a shaft portion 652, and a stopper portion 653 (see FIG. 4(b)).

[0055] The valve body 651 is a part that opens and closes the opening 64A. The valve body 651 is a circular plate member and is located at the boundary between the guide path S5 and the third space S3. In the present embodiment, one valve body 651 is provided so as to cover the opening 64A on the lower surface of the plate portion 642. The valve body 651 is formed of a material having elasticity such as an elastomer, and can close the opening 64A from below by its own elastic force or biasing force.

[0056] The shaft portion 652 is a rod-shaped member that restricts the moving direction of the valve body 651. The shaft portion 652 is provided so as to penetrate the center of the valve body 651. The shaft portion 652 is inserted into the through hole 64B.

[0057] The stopper portion 653 is a part that restricts the vertical movement of the valve body 651 and the shaft portion 652. The stopper portion 653 is a part formed so as to bulge radially from the shaft portion 652 at a part of the shaft portion 652. The stopper portion 653 is provided on the shaft portion 652 so as to contact the upper surface of the valve body 651. The diameter of the stopper portion 653 is larger than the diameter of the through hole 64B. For this reason, the stopper portion 653 contacts the plate portion 642 (the edge of the through hole 64B) and restricts the downward movement of the valve body 651.

[0058] The pressure in the cylindrical portion 641, that is, the pressure in the second space S2 communicating with the guide path S4, acts on the upper surface of the valve body 651. On the other hand, the pressure of the third space S3 acts on the lower surface of the valve body 651. When the pressure in the second space S2 is greater than the pressure in the third space S3, the valve body 651 deforms or moves downward to open the opening 64A.

[0059] On the other hand, when the pressure acting on the lower surface of the valve body 651 (that is, the pressure in the third space S3) becomes equal to or greater than the pressure in the second space S2 due to an increase in the flow rate of the gas to be processed flowing into the third space S3 or the like, the valve body 651 closes the opening 64A from below and brings the opening 64A into a closed state.

[0060] <Operation of the oil separator> Next, the separation of oil from the gas to be processed in the oil separator 2 will be described.

[0061] Blow-by gas is supplied from the engine 7 to the third space S3 in the oil drain 60 through the exhaust gas flow path 4 and the introduction cylinder 63. Further, the air compressed by the turbocharger 10 is supplied to the nozzle 54 through the compressed air flow path 3. The compressed high-pressure air is injected from the nozzle 54 and flows into the injection pipe 53 through the inlet 51. Since the compressed air is injected from the nozzle 54 at high speed, a low-pressure space is generated inside the inlet 51. Therefore, the blow-by gas passes through the opening 51A and the inside of the inlet 51 in this order and is sucked into the injection pipe 53.

[0062] Then, as shown by the white arrow in FIG. 7, 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 processed) are injected from the injection pipe 53 toward the side wall 31 in the circumferential direction. The white arrows in FIGS. 2, 3, 5, and 7 indicate the moving directions of each fluid such as blow-by gas, gas to be processed, compressed air, and oil.

[0063] The separation of oil from the gas to be processed in the oil separator 2 is classified into the following two processes: (1) centrifugal separation and (2) impacter separation.

[0064] (1) Centrifugal separation The gas to be processed injected from the injection pipe 53 moves along the inside of the side wall 31, that is, while rotating in the circumferential direction (FIG. 3). In the present embodiment, the gas to be processed moves downward while rotating counterclockwise along the inside of the side wall 31 when viewed from above. That is, when the gas to be processed is injected from the injection pipe 53, it becomes a vortex shape close to a spiral shape and moves downward.

[0065] When the gas to be processed 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 that narrows downward, the gas to be processed moves as a spiral vortex whose diameter gradually decreases downward.

[0066] Since the gas to be processed moves along side walls 31 and 41, the trajectory along which the gas to be processed moves is circular when viewed from above. Therefore, the oil contained in the gas to be processed is subjected to centrifugal force (a force directed radially outward). The oil subjected to centrifugal force gradually moves radially outward while riding on the vortex flow. When the oil contacts side wall 31 or side wall 41, the oil is separated from the gas to be processed. The separated oil is subjected to gravity and moves downward along side wall 31 or side wall 41. Further, since the groove portion 41A is formed in the groove portion 41A, the oil can avoid the wind pressure of the vortex flow in the groove portion 41A and can flow downward efficiently. The oil flowing downward passes through the small-diameter opening 43 and eventually reaches the oil drain 60.

[0067] When the separated oil reaches the oil drain 60, it flows into the oil flow path 5 through the opening 62A. The separated oil is returned to the engine 7 through the oil flow path 5.

[0068] (2) Impactor separation The gas to be processed in the first space S1 forms a vortex flow and separates oil by centrifugal separation, and then passes through the gas discharge portion 35. The gas to be processed that has passed through the gas discharge portion 35 flows into the second space S2 through the flow path of the notch portion 37A and the flow path formed by the hole 70A (FIG. 3).

[0069] Also, when the pressure in the first space S1 is higher than the set value with respect to the second space S2, as described above, the gas to be processed also passes through the gap flow path formed between the valve elastic body 72 and the connection portion 37.

[0070] When the inflow rate of the gas to be processed increases and the pressure in the first space S1 increases, the gap flow path formed by the valve elastic body 72 and the connection portion 37 opens wide. In this way, the valve 70 adjusts the opening degree of the flow path (the size and opening condition of the flow path), and adjusts the flow rate and speed of the gas to be processed passing through the valve 70 to a size suitable for oil separation by the collector 80.

[0071] When closing the gap flow path formed between the valve elastomer 72 and the connection part 37, the valve elastomer 72 may collide with the connection part 37 and generate a striking sound. However, since the flow path formed by the notch part 37A and the hole 70A allows a certain gas flow and a certain pressure fluctuation, the magnitude of the striking sound can be reduced compared to a valve without a flow path other than the gap flow path. This is because when a constantly open flow path is formed, the behavior of vibrating with each gas pressure fluctuation in the valve body 71 and the valve elastomer 72 is suppressed.

[0072] Also, since the gas to be processed hardly stays in the first space S1, the pressure of the gas to be processed in the first space S1 is less likely to rise compared to the case where there is no flow path formed by the notch part 37A or the hole 70A. That is, the frequency of opening and closing of the gap flow path is reduced, and the generation frequency of the striking sound is suppressed.

[0073] When the flow rate of the gas to be processed flowing into the first space S1 fluctuates in a state where the gap flow path is widely open, the magnitude of the force acting on the valve 70 due to the pressure of the gas to be processed becomes non-uniform. At this time, the valve body 71 and the valve elastomer 72 may be in an inclined state, and the flow of the gas to be processed may be disturbed. When the flow of the gas to be processed is disturbed, the flow velocity of the gas to be processed decreases, and the performance of the trapping body 80 (that is, the performance of trapping mist-like oil from the gas to be processed) deteriorates. However, since the cylindrical part 73 acts as a weight that lowers the center of gravity of the valve 70, the valve body 71 is less likely to tilt with respect to the connection part 37. As a result, even when the flow rate of the gas to be processed flowing into the first space S1 fluctuates in a state where the valve 70 has the gap flow path open, the flow of the blow-by gas passing through the gap flow path is less likely to be disturbed. Therefore, the performance of the trapping body 80 is less likely to deteriorate.

[0074] The gas to be processed flowing into the second space S2 travels almost perpendicularly to the inner peripheral surface of the trapping body 80 disposed opposite to each of the gap flow path, the flow path formed by the notch part 37A, and the flow path formed by the hole 70A, and passes through the inside of the trapping body 80. When passing through the inside of the trapping body 80, the oil contained in the gas to be processed is trapped by the trapping body 80.

[0075] The collected oil flows out from the collector 80 to the upper surface of the ceiling surface 32, and then is guided by the guiding path S4 and the guiding path S5 and moves downward. Further, the oil passes through the opening 64A and flows out into the third space S3. The oil that has passed through the opening 64A falls onto the upper surface of the bottom plate 62 and moves along the gradient of the upper surface of the bottom plate 62 and passes through the opening 62A. In this way, the oil flows out into the flow path 5.

[0076] The gas to be treated contains not only mist-like oil but also dust such as sludge. Since the gas to be treated passes through the collector 80, the gas to be treated can blow off the dust adhering to the collector 80. As described above, since the speed and flow rate of the gas to be treated are appropriately maintained, the dust adhering to the collector 80 is blown off by the gas to be treated and is easily discharged.

[0077] The gas to be treated in the second space S2 from which the oil has been separated passes through the exhaust cylinder 39 and flows out to the breather pipe 6 (FIGS. 2 and 3).

[0078] In addition, when the pressure in the third space S3 is equal to or higher than the pressure in the second space S2, the check valve 65 closes the opening 64A, so that a situation where blow-by gas in which oil separation has not been performed flows into the second space S2 is prevented. Therefore, even when the inflow amount of blow-by gas from the exhaust gas flow path 4 is large, the gas passes through the first space S1 and the second space S2 in this order and appropriately undergoes the process of oil separation treatment.

[0079] <Effect> The following aspects are disclosed in the above embodiment.

[0080] (Aspect 1) The oil separator 2 has a function of separating oil from gas containing mist-like oil, and mainly includes a housing having side walls 31, 41, and a ceiling portion 32 (corresponding to a partition wall), a lid portion 38, an injection portion 50, a valve body mainly composed of a valve body 71 and a valve elastic body 72, and a trapping body 80. The housing has side walls 31 and 41 formed in a cylindrical shape extending in the direction of the central axis 20A, and a first space S1 and a second space S2 separated by the ceiling portion 32 are formed inside. A communication hole is formed in the ceiling portion 32 by a gas discharge portion 35. The injection portion 50 injects the gas to be processed in the circumferential direction into the first space S1 inside the side wall 31, and rotates the gas to be processed in the circumferential direction. The valve body is installed in the communication hole to open and close the flow path communicating the first space S1 and the second space S2, and the higher the pressure in the first space S1 is compared with the pressure in the second space S2, the larger the opening degree of the flow path can be. Further, the trapping body 80 is disposed facing the flow path, has air permeability, and traps oil.

[0081] In the above configuration, it is possible to perform both the oil separation process by centrifugal separation and the oil separation process by an impactor. Generally, the separation of mist-like oil by centrifugal separation has high separation efficiency when the engine is under high load (high load), but the separation efficiency is low during idling or when the low-load turbocharger is not operating (low load). On the other hand, in the oil separation process by an impactor, although the separation efficiency at high load is lower than that of the centrifugal separation type, the separation efficiency at low load is higher than that of the process by centrifugal separation.

[0082] In the above configuration, by suitably combining the lid portion 38, the injection portion 50, the valve body, and the trapping body 80, two different oil separation processing methods are combined to obtain high separation efficiency at both low load and high load. In particular, by appropriately adjusting the opening degree of the flow path by the valve body, the flow rate and flow velocity of the gas to be processed in each of the first space S1 and the second space can be controlled to be suitable for each oil separation processing method. Therefore, high separation efficiency can be achieved regardless of the high or low load of the engine.

[0083] (Aspect 2) In Aspect 1, the trapping body 80 is arranged to face the flow path.

[0084] With the above configuration, the trapping body 80 can efficiently separate oil from the gas to be processed.

[0085] (Aspect 3) In Aspect 1 or 2, the oil separator 2 further includes a spring 74 that biases against the pressure in the first space S1 so that the valve body covers the communication hole (opening 37B).

[0086] With the above configuration, the flow rate and flow velocity of the gas to be processed can be controlled with a simple configuration.

[0087] (Aspect 4) In any one of Aspects 1 to 3, the valve body has a cylindrical portion 73 that extends in the direction of the central axis 20A and protrudes into the first space S1 in addition to the valve body 71 and the valve elastic body 72.

[0088] In the above configuration, since the valve body is provided with the cylindrical portion 73, the valve body is prevented from tilting or exhibiting unnatural behavior as described above. Therefore, an unbalanced flow of gas and a decrease in the oil separation efficiency are prevented.

[0089] (Aspect 5) In any one of Aspects 1 to 4, the injection unit 50 injects the gas to be processed into the first space by sucking the blow-by gas together with the injection of the high-pressure fluid.

[0090] In the above configuration, since the gas to be processed is injected into the side walls 31 and 41 at high speed, an oil separation process by centrifugal separation can be performed with high efficiency.

[0091] (Aspect 6) In any one of Aspects 1 to 5, the oil separator 2 further includes an oil drain 60 that forms a third space S3 inside into which the oil discharged from the housing flows. The oil drain 60 supplies the blow-by gas from the third space S3 to the injection unit 50.

[0092] In the above configuration, since the oil drain 60 has two functions of receiving oil and receiving blow-by gas, a compact configuration can be achieved.

[0093] (Aspect 7) In any one of Aspects 1 to 6, the housing has one end in the direction of the central axis 20A in which a communication hole is formed, and the other end (near the small-diameter opening 43) on the opposite side in the axial direction to the one end. The injection part 50 is connected to the one end, and the oil drain 60 is provided so as to surround the other end.

[0094] In the above configuration, the oil drain 60 can receive the oil flowing out from the housing without leakage with a compact configuration. Further, even when a part of the gas to be processed flows out from the housing, the gas can be supplied again to the injection part 50 to perform the oil separation process. Therefore, high separation efficiency can be maintained.

[0095] (Aspect 8) In any one of Aspects 1 to 7, guide paths S4, S5 for communicating the second space S2 and the third space S3 are formed.

[0096] By providing the guide paths S4, S5, the oil separated in the second space S2 can be guided into the oil drain 60.

[0097] (Aspect 9) In any one of Aspects 1 to 8, the oil separator 2 further includes a check valve 65 installed in the guide path S5. The check valve 65 closes the guide path S5 when the pressure in the third space S3 is equal to or greater than the pressure in the second space S2.

[0098] In the above configuration, a situation where blow-by gas in which oil separation has not been performed flows into the second space S2 is prevented. Therefore, even when the inflow amount of blow-by gas is large, the gas passes through the first space S1 and the second space S2 in this order and can appropriately go through the process of oil separation treatment. Therefore, high separation efficiency is maintained.

[0099] <Modification Example> The injection unit 50 does not necessarily include the nozzle 54. In this case, the compressed air flow path 3 is connected to one end of the inlet 51. The compressed air is supplied from the inlet 51 to the injection pipe 53. The blow-by gas is supplied from the inlet 51 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 toward the side wall 31 in the circumferential direction.

Explanation of reference numerals

[0100] 2…Oil separator 20…Main body 30…Upper main body (main body) 40…Lower main body (main body) 50…Injection unit 60…Oil drain 70…Valve 80…Collecting body 90…Holding member

Claims

1. An oil separator for separating oil from a gas containing mist-like oil, comprising: a housing having a side wall formed in a cylindrical shape extending in the axial direction, with a first space inside the side wall and a second space outside the side wall formed therein, the housing having a partition wall that forms a communication hole for communicating the first space and the second space and forms a boundary between the first space and the second space; an injection part connected to the housing, injecting the gas in the circumferential direction of the side wall into the first space, and rotating the gas in the circumferential direction in the axial view; a valve body provided in the communication hole for opening and closing a flow path communicating the first space and the second space, and increasing the opening degree of the flow path as the pressure in the first space is higher than the pressure in the second space; a trapping body disposed opposite to the flow path and having air permeability for trapping the oil; an oil separator comprising the above.

2. The oil separator according to claim 1, wherein the trapping body is disposed so as to face the flow path. The oil separator according to claim 1.

3. The oil separator according to claim 1, further comprising a biasing member that biases the valve body so as to cover the communication hole and against the pressure in the first space. The oil separator according to claim 1.

4. The oil separator according to claim 1, wherein the valve body has a cylindrical portion extending in the axial direction and protruding into the first space. The oil separator according to claim 1.

5. The oil separator according to claim 1, wherein the injection part injects the gas into the first space by sucking the gas together with the injection of high-pressure fluid. The oil separator according to claim 1.

6. The oil separator according to claim 1, further comprising an oil drain having a third space formed therein into which the oil discharged from the housing flows, wherein the oil drain supplies the gas from the third space to the injection part. The oil separator according to claim 1.

7. The housing has one end portion in the axial direction where the communication hole is formed and the other end portion on the opposite side of the axial direction with respect to the one end portion, the injection part is connected to the one end portion, the oil drain surrounds the other end portion. The oil separator according to claim 6.

8. The oil separator according to claim 6 or 7, further comprising a guiding path for communicating the second space and the third space. The oil separator according to claim 6 or 7.

9. The oil separator according to claim 8, further comprising a check valve installed in the guiding path, wherein the check valve closes the guiding path when the pressure in the third space is equal to or higher than the pressure in the second space. The oil separator according to claim 8.

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