JP2009103117A - Engine blow-by gas returning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect a PCV valve or a crank case from an excessive pressure rise even when a pressure in an intake passage rapidly increases and is applied on a returning passage. <P>SOLUTION: This blow-by gas returning apparatus is arranged to allow blow-by gas leaking from a combustion chamber 2 of an engine 1 into a crank chamber 7 to flow in an intake passage 21 through a returning passage 32 and return it to the combustion chamber 2, and to regulate a flow rate of the blow-by gas by a PCV valve 33 placed in the returning passage 32. A supercharger 27 is placed in the intake passage 21. The PCV valve 33 is adapted to change a position of a valve element by an electromagnetic force to change a passage opening area. A check valve 55 is placed integral with the PCV valve 33 in the returning passage 32 between the valve element of the PCV valve 33 and the intake passage 21. The check valve 55 is arranged to inhibit a back-flow of the gas from the intake passage 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine blow-by gas reduction device that returns blow-by gas leaked from a combustion chamber of an engine into a crankcase to an intake system of the engine and returns it to the combustion chamber.

  Conventionally, as this type of technique, the techniques described in Patent Documents 1 to 4 below are known. In particular, Patent Document 1 describes that the flow rate of blow-by gas in the reduction passage is adjusted by an electromagnetically driven PCV valve.

  On the other hand, in Patent Document 2, in an engine equipped with a supercharger, a first reduction passage for flowing blow-by gas from the engine body into an intake passage upstream of the supercharger, and an intake passage downstream of the supercharger. And a second reduction passage through which blow-by gas flows from the engine body, and a check valve for stopping the backflow of gas from the intake passage is provided in each of the reduction passages. Further, in Patent Document 3, in an engine equipped with a supercharger, a first reduction passage for flowing blow-by gas from the engine body into an intake passage upstream of the supercharger, and an intake passage downstream of the supercharger Each of the reduction passages is provided with a check valve for stopping the reverse flow of the gas from the intake passage, and the negative pressure level of each reduction passage is common 1 It is described that it can be adjusted by a single control device. Further, in Patent Document 4, in an engine equipped with a supercharger, a first reduction passage for flowing blow-by gas from the engine body into an intake passage upstream of the supercharger, and an intake passage downstream of the supercharger. And a second reduction passage through which blow-by gas flows from the engine body. A PCV valve is provided in the second reduction passage, and an on-off valve that closes the second reduction passage when the PCV valve is opened. Is provided.

JP-A-8-338222 Japanese Utility Model Publication No. 56-129556 JP 2003-184532 A Japanese Patent Laid-Open No. 62-150514

  However, when the technique described in Patent Document 1 is applied to an engine equipped with a supercharger as in Patent Documents 2 to 4, the pressure in the intake passage suddenly increases due to supercharging by the supercharger or backfire. At times, high pressure gas may flow back through the reduction passage and flow into the PCV valve. Here, since the PCV valve is an electromagnetically driven valve, the PCV valve is not closed by the action of the high-pressure gas flowing backward. For this reason, if the high-pressure gas flows backward to the PCV valve, the valve body and crankcase of the PCV valve may be damaged.

  The present invention has been made in view of the above circumstances, and its purpose is to prevent the PCV valve or the crankcase from being excessively increased even if the pressure in the intake passage suddenly increases and acts on the reduction passage. An object of the present invention is to provide a blow-by gas reduction device for an engine that can be protected.

  In order to achieve the above object, the invention according to claim 1 is directed to reducing the blow-by gas leaked from the combustion chamber of the engine into the crankcase into the intake passage through the reduction passage and reducing it to the combustion chamber. In an engine blow-by gas reduction device in which the flow rate of blow-by gas is adjusted by a PCV valve provided in the reduction passage, the PCV valve can change the opening area of the flow path by changing the position of the valve body by electromagnetic force. Therefore, the purpose is that a suppression valve for suppressing the backflow of gas from the intake passage is provided in the reduction passage between the crankcase and the valve body of the PCV valve.

  According to the configuration of the above invention, when the pressure in the intake passage suddenly increases due to the backfire from the combustion chamber, the suppression valve operates to suppress the backflow of gas from the intake passage into the crankcase. The

  In order to achieve the above object, the invention according to claim 2 is directed to reducing the blow-by gas leaked from the combustion chamber of the engine into the crankcase into the intake passage through the reduction passage and reducing it to the combustion chamber. In an engine blow-by gas reduction device in which the flow rate of blow-by gas is adjusted by a PCV valve provided in the reduction passage, the PCV valve can change the opening area of the flow path by changing the position of the valve body by electromagnetic force. Therefore, the purpose of the present invention is to provide a reduction valve for suppressing the backflow of gas from the intake passage in the reduction passage between the valve body of the PCV valve and the intake passage.

  According to the configuration of the above invention, when the pressure in the intake passage suddenly increases due to the backfire from the combustion chamber, the suppression valve operates to suppress the backflow of gas from the intake passage into the PCV valve. The

  In order to achieve the above object, according to a third aspect of the present invention, in the second aspect of the present invention, the suppression valve and the valve body collide with each other when the valve body is closed when the suppression valve is closed. It is intended that it is provided at such a position.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 2, even if the suppression valve is fixed in a closed state, the suppression valve and the valve body collide by closing the valve body, The fixed state of the suppression valve is forcibly released.

  In order to achieve the above object, a fourth aspect of the present invention is the invention according to any one of the first to third aspects, wherein the intake air pressure is increased upstream from the opening of the reduction passage in the intake passage. And a second reduction passage is provided with one end communicating with a reduction passage between the suppression valve and the crankcase, and the other end communicating with an intake passage upstream of the supercharger. The second PCV valve is provided in the reduction passage, and the second PCV valve is intended to change the flow path opening area by changing the position of the valve body by the pressure.

  According to the configuration of the invention, in addition to the requirement of the invention described in any one of claims 1 to 3, the flow of blow-by gas from the reduction passage to the intake passage is prevented by operating the suppression valve, The blow-by gas pressure in the crankcase may increase. At this time, the second PCV valve changes the flow path opening area by changing the position of the valve body by pressure, so that the blow-by gas in the crankcase is supercharged through the second reduction passage. To the intake passage on the upstream side.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the fourth aspect of the present invention, a fresh air passage for introducing fresh air is provided in the crankcase, and an inlet of the fresh air passage is an intake air. The purpose is to communicate with the downstream side of the supercharger in the passage.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 4, the intake air flowing through the intake passage on the downstream side of the supercharger flows as fresh air from the inlet to the fresh air passage and is introduced into the crankcase. .

  In order to achieve the above object, the invention according to claim 6 is the invention according to claim 4 or 5, wherein the second PCV valve is a pressure difference between the upstream side and the downstream side of the second PCV valve. The purpose is that the larger the is, the larger the channel opening area becomes.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 4 or 5, the pressure on the upstream side and the downstream side of the second PCV valve increases as the pressure of the blowby gas in the crankcase increases. The difference increases, the flow path opening area of the second PCV valve increases, and more blow-by gas flows through the second reduction passage to the intake passage upstream of the supercharger.

  In order to achieve the above object, the invention according to claim 7 is directed to reducing blowby gas leaked from the combustion chamber of the engine into the crankcase into the intake passage through the reduction passage and reducing the blowby gas to the combustion chamber. In an engine blow-by gas reduction device in which the flow rate of blow-by gas is adjusted by a PCV valve provided in the reduction passage, a supercharger is provided in the intake passage, and the position of the valve body of the PCV valve is variable by pressure. The flow passage opening area is variable, and the reduction passage has one end communicating with the crankcase and the other end communicating with the intake passage downstream of the supercharger, A suppression valve provided in the reduction passage for suppressing the flow of gas from the intake passage, one end communicating with the reduction passage between the suppression valve and the crankcase, and the other end of the intake air upstream of the turbocharger Through The second reduction passage communicating with the second reduction passage, the second PCV valve provided in the second reduction passage, and the second PCV valve can change the opening area of the flow path by changing the position of the valve body by pressure. The second PCV valve is intended to increase the flow path opening area as the difference in pressure between the upstream side and the downstream side of the second PCV valve increases.

  According to the configuration of the present invention, when the pressure in the intake passage suddenly increases due to the backfire or supercharging pressure from the combustion chamber, the suppression valve is activated and the gas from the intake passage to the PCV valve or the crankcase is Backflow is suppressed. Further, when the suppression valve is operated, the flow of blow-by gas from the reduction passage to the intake passage is blocked, and there is a possibility that the pressure of the blow-by gas in the crankcase increases. At this time, the flow passage opening area is changed by changing the position of the valve body of the second PCV valve by pressure, so that the blow-by gas in the crankcase is sucked into the intake air upstream of the supercharger through the second reduction passage. It is poured into the passage. Furthermore, as the pressure of the blow-by gas in the crankcase increases, the difference in pressure between the upstream side and the downstream side of the second PCV valve increases, and the flow path opening area of the second PCV valve increases, A lot of blow-by gas flows through the second reduction passage to the intake passage.

  In order to achieve the above object, according to an eighth aspect of the present invention, in the seventh aspect of the present invention, a fresh air passage for introducing fresh air is provided in the crankcase, and the inlet of the fresh air passage is an intake air. The purpose is to communicate with the downstream side of the supercharger in the passage.

  According to the configuration of the invention, in addition to the action of the invention according to claim 7, the intake air flowing through the intake passage on the downstream side of the supercharger enters the fresh air passage from the inlet as fresh air and flows into the crankcase. It is.

  According to the first aspect of the present invention, even if the pressure in the intake passage suddenly increases and acts on the reduction passage, the crankcase can be protected from excessive pressure increase.

  According to the second aspect of the present invention, even if the pressure in the intake passage suddenly increases and acts on the reduction passage, the PCV valve and the crankcase can be protected from excessive pressure increase.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 2, it is possible to prevent malfunction due to sticking of the suppression valve.

  According to the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, the suppression valve is in a state of suppressing the backflow of gas from the intake passage by the supercharging pressure, Even if the blow-by gas stops flowing into the reduction passage, the blow-by gas flows into the intake passage through the second reduction passage, so that the crankcase and the PCV valve can be protected from excessive pressure rise.

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 4, the inside of the crankcase can be effectively scavenged with fresh air.

  According to the invention described in claim 6, in addition to the effect of the invention described in claim 4 or 5, blow-by gas can be caused to flow into the intake passage in accordance with the degree of pressure in the crankcase.

  According to the seventh aspect of the present invention, even if the pressure in the intake passage suddenly increases due to an increase in the supercharging pressure and acts on the reduction passage, the PCV valve and the crankcase are protected from excessive pressure increase. can do.

  According to the invention described in claim 8, in addition to the effect of the invention described in claim 7, the inside of the crankcase can be effectively scavenged with fresh air.

[First Embodiment]
Hereinafter, a first embodiment of an engine blow-by gas reduction device according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a gasoline engine system including a blow-by gas reduction device of this embodiment. An engine 1 constituting this engine system is a direct injection type multi-cylinder spark ignition engine that directly injects fuel into a combustion chamber 2. A plurality of cylinder bores 4 are formed in the engine block 3 constituting the engine 1, and a piston 5 is provided in each cylinder bore 4 so as to be movable up and down. A crankcase 3a is provided below the engine block 3, and an oil pan 6 is assembled to the crankcase 3a. A crank chamber 7 is formed by the crankcase 3 a and the oil pan 6. A crankshaft 8 is rotatably supported in the crank chamber 7, and each piston 5 is connected to the crankshaft 8 via a connecting rod 9.

  The combustion chamber 2 formed on the upper side of the piston 5 in each cylinder bore 4 has an inclined pent roof shape whose upper center is raised. Corresponding to each combustion chamber 2, an intake port 10 and an exhaust port 11 are formed in the upper part of the engine block 3. The intake port 10 is provided with an intake valve 12, and the exhaust port 11 is provided with an exhaust valve 13. Each intake valve 12 and each exhaust valve 13 are opened and closed in conjunction with the rotation of the crankshaft 8 by a known valve mechanism 14. When the intake valve 12 and the exhaust valve 13 are opened and closed, outside air is introduced from the intake port 10 to the combustion chamber 2, and exhaust gas after combustion is discharged from the combustion chamber 2 to the exhaust port 11. An engine cover 15 that covers the valve operating mechanism 14 and the like is provided on the upper portion of the engine block 3.

  The intake port 10 is connected to an intake passage 21 including an intake manifold and an intake pipe. An air cleaner 22 is provided at the inlet of the intake passage 21. A throttle valve 23 is provided in the middle of the intake passage 21. The throttle valve 23 is opened and closed in conjunction with an operation of an accelerator pedal (not shown) provided at the driver's seat. The air purified by the air cleaner 22 is sucked into the combustion chamber 2 through the intake passage 21 and the intake port 10. The intake air amount is adjusted according to the opening of the throttle valve 23. An injector 24 for directly injecting fuel into each combustion chamber 2 is attached to the engine block 3. The fuel injected from the injector 24 into the combustion chamber 2 forms an air-fuel mixture with the air sucked into the combustion chamber 2 from the intake port 10. A spark plug 25 for igniting the air-fuel mixture in each combustion chamber 2 is provided at the top of the engine block 3.

  An exhaust passage 26 including an exhaust manifold and an exhaust pipe is connected to the exhaust port 11. Exhaust gas after combustion generated in each combustion chamber 2 is discharged to the outside through the exhaust port 11 and the exhaust passage 26.

  In this embodiment, the intake passage 21 and the exhaust passage 26 are provided with a supercharger 27 for boosting the intake air in the intake passage 21. The supercharger 27 includes a compressor 28 disposed in the intake passage 21, a turbine 29 disposed in the exhaust passage 26, and a rotary shaft 30 that rotates the compressors 28 and 29 integrally by providing the compressor 28 and the turbine 29 at both ends. Including. In the supercharger 27, the turbine 29 is rotated by the exhaust gas flowing through the exhaust passage 26, and the compressor 28 is integrally rotated via the rotary shaft 30, whereby the intake air in the intake passage 21 is boosted. To be done.

  The engine 1 described above is provided with a blow-by gas reduction device for flowing blow-by gas leaked from each combustion chamber 2 into the crankcase 3 a (crank chamber 7) into the intake passage 21 and reducing it to each combustion chamber 2. It is done. In other words, the oil separator 31 communicating with the crank chamber 7 is provided in the crankcase 3a. The oil separator 31 has a function of separating and capturing oil components such as lubricating oil mixed in the blow-by gas in the crank chamber 7 from the blow-by gas. Between the oil separator 31 and the intake passage 21 downstream from the throttle valve 23, a reduction passage 32 configured by a reduction pipe or the like is provided for flowing blow-by gas from the crank chamber 7 to the intake passage 21. A PCV valve 33 for adjusting the blow-by gas flow rate is provided in the middle of the reduction passage 32. The detailed configuration of the PCV valve 33 will be described later. A fresh air passage 34 is provided between the intake passage 21 and the engine cover 15 for introducing the intake air into the crank chamber 7 as fresh air in order to scavenge blow-by gas in the crank chamber 7. The inlet 34 a of the fresh air passage 34 is provided upstream of the throttle valve 23 in the intake passage 21 and communicates with a position downstream of the compressor 28 of the supercharger 27. The engine block 3 is formed with a vent hole 35 that allows the crank chamber 7 to communicate with the engine cover 15. The fresh air introduced into the engine cover 15 is guided to the crank chamber 7 through the vent hole 35. The ventilation hole 35 also constitutes a part of the fresh air passage 34. A pressure control valve 36 is provided in the middle of the fresh air passage 34. The pressure control valve 36 is configured to close the fresh air passage 34 when a high supercharging pressure by the supercharger 27 is applied to the fresh air passage 34.

  The opening 32 a of the reduction passage 32 in the intake passage 21 is disposed on the downstream side of the throttle valve 23. With this arrangement, intake negative pressure generated on the downstream side of the throttle valve 23 acts on the reduction passage 32 through the opening 32a. The compressor 28 of the supercharger 27 is disposed upstream of the opening 32 a of the reduction passage 32 and the throttle valve 23 in the intake passage 21.

  Here, the configuration of the PCV valve 33 will be described in detail. FIG. 2 is a sectional view showing the PCV valve 33. As shown in FIG. 2, the PCV valve 33 is configured to change the flow path opening area of the valve body 41 by changing the position of the valve body 41 by electromagnetic force, and has a hollow resin housing. 42 is provided. The housing 42 includes a main housing 43 and a sub housing 44 that are assembled together.

  The main housing 43 includes a connector portion 43 a formed at an upper portion thereof and a step motor 45 provided integrally therein, and a valve body 41 is provided on an output shaft 46 of the step motor 45. Step motor 45 includes a stator 47 that generates electromagnetic force, and a rotor 48 that is provided integrally with output shaft 46 at the center of stator 47. The output shaft 46 and the valve body 41 are connected in a relationship between a screw thread and a screw groove. The distal end portion of the external terminal 49 extending from the stator 47 is disposed in the connector portion 43a.

  The sub-housing 44 is formed with a valve chamber 50 that houses the valve body 41 and two ports 51 and 52 that communicate with the valve chamber 50. The valve chamber 50 is provided to be slidable along the axial direction in a state in which the valve body 41 is prevented from rotating. One inlet port 51 communicates with the oil separator 31 and receives blow-by gas from the crank chamber 7. The other outlet port 52 communicates with the reduction passage 32 and leads out blow-by gas. Therefore, the sub-housing 44 including the inlet port 51, the valve chamber 50, and the outlet port 52, which serve as a blow-by gas passage, constitutes a part of the reduction passage of the present invention. Pipe fittings 53 and 54 are formed in the sub housing 44 corresponding to the inlet port 51 and the outlet port 52. The outlet port 52 is formed coaxially with the central axis of the valve body 41, and the tip end portion 41a of the valve body 41 can enter from the one end opening 52a. Since the tip 41 a of the valve body 41 has a tapered shape, the flow between the opening 52 a of the outlet port 52 and the tip 41 a of the valve body 41 increases as the tip 41 a enters the outlet port 52. The road opening area (opening) is reduced. Therefore, as the output shaft 46 of the step motor 45 rotates forward and the valve body 41 approaches the outlet port 52, the opening degree between the outlet port 52 and the valve body 41 becomes smaller. As the output shaft 46 of the step motor 45 reverses and the valve body 41 retreats from the outlet port 52, the opening between the outlet port 52 and the valve body 41 increases.

  In the sub-housing 44, the present invention for suppressing the back flow of gas from the intake passage 21 in the middle of the outlet port 52, that is, in the reduction passage between the valve body 41 of the PCV valve 33 and the intake passage 21. A ball check valve 55 corresponding to the valve is provided. The check valve 55 includes a ball 56 and a spring 57 which are accommodated in a valve chamber 58 formed in the middle of the outlet port 52. A valve seat 59 corresponding to the ball 56 is formed on the inner wall of the valve chamber 58. When the high-pressure gas acts from the intake passage 21 to the outlet port 52, the ball 56 is seated on the valve seat 59 against the spring 57, whereby the check valve 55 is closed and the high-pressure gas from the intake passage 21 is closed. Back flow is suppressed. A partition plate 60 is provided on the outlet side of the valve chamber 58. Although not shown in FIG. 2, the partition plate 60 has a plurality of holes penetrating in the plate thickness direction, and a gas flow is allowed through the holes. A plurality of grooves 58a are formed along the longitudinal direction of the inner wall of the valve chamber 58, and a gas flow is allowed through the grooves 58a.

  According to the blow-by gas reduction device of this embodiment described above, the reverse provided at the outlet port 52 of the PCV valve 33 when the pressure in the intake passage 21 suddenly increases due to the backfire from the combustion chamber 2. The stop valve 55 is operated, and the backflow of the high-pressure gas from the intake passage 21 into the PCV valve 33 is suppressed. Even when the supercharger 27 is activated and the intake pressure suddenly increases due to the supercharging pressure, the check valve 55 is also activated, and the backflow of the high-pressure gas from the intake passage 21 into the PCV valve 33 is suppressed. The For this reason, it is possible to protect the PCV valve 33 and the crankcase 3a and the oil pan 6 located upstream thereof from excessive pressure rise. In particular, in this embodiment, since the backfire pressure is not applied to the valve body 41 and the step motor 45 constituting the PCV valve 33, it is not necessary to make these components 41 and 45 strong enough to withstand the backfire pressure. The PCV valve 33 can be reduced in weight and cost. Further, since no supercharging pressure is applied to the crank chamber 7, oil is not taken away from the crank chamber 7 through the fresh air passage 34, and oil consumption can be suppressed.

  In this embodiment, the fresh air passage 34 communicates the inlet 34 a with the intake passage 21 on the downstream side of the supercharger 27. Accordingly, the intake air flowing through the intake passage 21 on the downstream side of the supercharger 27 flows as fresh air from the inlet 34 a to the fresh air passage 34 and is introduced into the crank chamber 7. For this reason, the crank chamber 7 can be effectively scavenged with fresh air. Further, when a high supercharging pressure by the supercharger 27 is applied to the fresh air passage 34, the fresh air passage 34 is closed by the pressure control valve 36, so that an excessive supercharging pressure is supplied to the crank chamber 7 through the fresh air passage 32. Will not take. Also in this sense, the crankcase 3a and the oil pan 6 can be protected from excessive pressure rise.

[Second Embodiment]
Next, a second embodiment of the engine blow-by gas reduction device according to the present invention will be described in detail with reference to the drawings.

  In each embodiment described below, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and different points will be mainly described below.

  FIG. 3 is a sectional view showing the PCV valve 61 of this embodiment. The blow-by gas reduction device of this embodiment is different from the first embodiment in the configuration of the PCV valve 61. That is, the PCV valve 61 is different from the first embodiment in the shape of the sub housing 44 and the arrangement of the check valve 55. The sub housing 44 is formed shorter in the axial direction than the sub housing 44 of the first embodiment. In this embodiment, a check valve 55 is provided at the inlet port 51. The configuration of the check valve 55 is the same as that of the first embodiment. A high pressure gas acts on the outlet port 52 and the valve chamber 50 of the PCV valve 61 from the intake passage 21 through the reduction passage 34, so that the ball 56 is seated on the valve seat 59 against the spring 57, thereby checking the check valve. 55 closes and the backflow of the high-pressure gas from the intake passage 21 is suppressed.

  Therefore, also in this embodiment, when the pressure in the intake passage 21 is suddenly increased by the backfire or when the intake pressure is suddenly increased by the supercharging pressure of the supercharger 27, the inlet port of the PCV valve 61 is used. The check valve 55 provided in 51 is operated, and the backflow of the high-pressure gas from the intake passage 21 to the crank chamber 7 is suppressed. For this reason, the crankcase 3a and the oil pan 6 can be protected from an excessive pressure rise. Further, unlike the first embodiment, in this embodiment, high-pressure gas flows into the valve chamber 50 of the PCV valve 61. However, the components such as the valve body 41 and the step motor 45 can be made strong. The durability of these parts against high-pressure gas can be ensured. Also in this embodiment, since the supercharging pressure is not applied to the crank chamber 7, oil is not taken away from the crank chamber 7 through the fresh air passage 34, and oil consumption can be suppressed. Other functions and effects in this embodiment are the same as those in the first embodiment.

[Third Embodiment]
Next, a third embodiment of the engine blow-by gas reduction device according to the present invention will be described in detail with reference to the drawings.

  FIG. 4 is a schematic configuration diagram showing a gasoline engine system including the blow-by gas reduction device of this embodiment. FIG. 5 is a sectional view showing the first PCV valve 62 of this embodiment. This embodiment is different from the above embodiments in terms of the passage configuration of the blow-by gas reduction device, the configuration of the first PCV valve 62, and the like. That is, as shown in FIG. 4, the blow-by gas reduction device further includes a second reduction passage 63 and a second PCV valve 64. The second PCV valve 64 is provided integrally with the first PCV valve 62. The second reduction passage 63 is provided so that one end is connected to the second PCV valve 64 and the other end communicates with the intake passage 21 on the upstream side of the supercharger 27. As shown in FIG. 5, the first PCV valve 62 is different from the first embodiment in the configuration of the sub-housing 44. The sub housing 44 is composed of a plurality of blocks assembled to each other. The sub housing 44 is provided with a check valve 55 in the middle of the outlet port 52. Further, the sub housing 44 is formed with a screw portion 65 communicating with the valve chamber 50. The second PCV valve 64 is assembled to the screw portion 65.

  The second PCV valve 64 includes a hollow housing 73 formed by assembling two housing members 71 and 72. The first housing member 71 is fastened and fixed to the screw portion 65 of the first PCV valve 62 via a seal ring 74 attached to the outer periphery. The outer periphery of the base end portion of the second housing member 72 is fixed to the distal end opening of the first housing member 71 by ultrasonic welding. A distal end portion of the second housing member 72 is a pipe joint 75. One end of a pipe constituting the second reduction passage 63 is connected to the pipe joint 75. The hollow portion of the first housing member 71 is a valve chamber 77 that houses the valve body 76. An inlet 78 communicating with the valve chamber 50 of the first PCV valve 62 is formed in the first housing member 71 at one end of the valve chamber 77. The valve chamber 77 of the first housing member 71 communicates with the hollow portion 79 of the second housing member 72. An annular valve seat 80 is provided between the housing members 71 and 72. The valve body 76 disposed in the valve chamber 77 is provided so as to be able to penetrate the valve seat 80. The valve body 76 has a base end portion 76a (lower side in the drawing) having a cylindrical shape, and a distal end portion 76b (upper side in the drawing) having a two-step taper shape. The distal end portion 76b has a shape that gradually increases in diameter toward the distal end. Accordingly, when the valve body 76 moves toward the valve seat 80, the flow path opening area (opening) between the valve seat 80 and the valve body 76 changes so as to gradually increase. The valve body 76 is provided with a flange 76c at the end of the base end portion 76a. A compression spring 81 is provided between the valve seat 80 and the flange 76c. The spring 81 urges the valve body 76 toward the inlet 78, that is, in a direction to reduce the flow path opening area (valve closing direction). The distal end portion 76 b of the valve body 76 is provided so as to penetrate the valve seat 80 and enter the hollow portion 79 of the second housing member 72. The hollow portion 79 of the second housing member 72 is provided with another compression spring 82 that restricts the movement of the valve body 76. The valve chamber 77 and the hollow portion 79 of the second PCV valve 64 described above constitute a part of the second reduction passage 63.

  Therefore, when the check valve 55 is closed, blow-by gas that has entered the valve chamber 50 from the inlet port 51 of the first PCV valve 62 enters the valve chamber 77 from the inlet 78 of the second PCV valve 64. The gas pressure acts on the proximal end portion 76 a of the valve body 76. Further, atmospheric pressure acts on the distal end portion 76 b of the valve body 76 from the intake passage 21 through the second reduction passage 63. Based on the pressure (difference) between the pressure acting on the proximal end portion 76a and the distal end portion 76b of the valve body 76 and the urging force of the spring 81 (pressure difference), the valve body 76 moves in its axial direction, and the valve seat 80 and the valve The channel opening area (opening degree) between the body 76 and the body 76 is changed. As a result, the blow-by gas flow rate from the valve chamber 77 to the hollow portion 79, that is, measured by the second PCV valve 64 is adjusted. Thus, the second PCV valve 64 changes the position of the valve element 76 by the action of the blow-by gas pressure so as to change the flow path opening area (opening degree) between the second PCV valve 64 and the valve seat 80. It has become.

  Therefore, according to the blow-by gas reduction device of this embodiment, when the check valve 55 of the first PCV valve 62 is operated and the outlet port 52 is closed, the pressure of the blow-by gas in the crank chamber 7 is The gas enters the valve chamber 50 from the inlet port 51 of the PCV valve 62, but the gas enters the valve chamber 77 from the inlet 78 of the second PCV valve 64. At this time, based on the pressure difference between the upstream side and the downstream side of the second PCV valve 64, the valve body 76 moves to increase the flow path opening area (opening degree), and the blow-by gas in the crank chamber 7 is increased. Flows into the intake passage 21 upstream of the supercharger 27 through the second reduction passage 63. For this reason, even if the check valve 55 is closed by the supercharging pressure and the blow-by gas does not flow through the reduction passage 34, the blow-by gas flows into the intake passage 21 through the second reduction passage 63. Therefore, the crankcase 3a, The oil pan 6 and the first PCV valve 62 can be protected from excessive pressure increase of blow-by gas.

  In addition, in this embodiment, the second PCV valve 64 is configured such that the flow path opening area (opening degree) increases as the difference in pressure between the upstream side and the downstream side increases. Therefore, as the blow-by gas pressure in the crank chamber 7 increases, the pressure difference between the upstream side and the downstream side of the second PCV valve 64 increases, and the flow passage opening area (opening) of the second PCV valve 64 increases. Degree) and more blow-by gas flows through the second reduction passage 63 to the intake passage 21. For this reason, blow-by gas can effectively flow into the intake passage 21 in accordance with the degree of pressure increase in the crank chamber 7.

[Fourth Embodiment]
Next, a fourth embodiment of the engine blow-by gas reduction device according to the present invention will be described in detail with reference to the drawings.

  FIG. 6 is a sectional view showing the composite PCV valve 86 of this embodiment. This embodiment differs from the third embodiment in the configuration of the first and second PCV valves. That is, as shown in FIG. 6, the composite PCV valve 86 is a valve block 87 in which a first PCV valve 88 and a second PCV valve 64 are integrally provided. The second PCV valve 64 is the same as that of the third embodiment. The first PCV valve 88 does not change the position of the valve element 41 by electromagnetic force, that is, the step motor 45, as in the first to third embodiments, but changes the position of the valve element 89 by pressure. It is what. The valve block 87 includes a hollow portion 90 formed therein, an inlet port 91 that communicates with the hollow portion 90, and a first assembly hole 92 and a second assembly hole 93 that communicate with the hollow portion 90. . A first PCV valve 88 is assembled in the first assembly hole 92, and a second PCV valve 64 is assembled in the second assembly hole 93. The configuration of the first PCV valve 88 is similar to the configuration of the second PCV valve 64, but only the shape of the valve body 89 is different. The valve body 89 of the first PCV valve 88 has a tapered shape in which the distal end portion 89a is gradually reduced in diameter toward the distal end. A compression spring 81 is provided between the flange 89 b at the base end of the valve body 89 and the valve seat 80. Accordingly, when the valve body 89 moves toward the valve seat 80, the flow path opening area (opening) between the valve seat 80 and the valve body 89 changes so as to gradually decrease. A pipe constituting the reduction passage 34 is connected to the pipe joint 75 of the first PCV valve 88. A pipe constituting the second reduction passage 63 is connected to the pipe joint 75 of the second PCV valve 64. The oil separator 31 is connected to a pipe joint 94 formed corresponding to the inlet port 91.

  Therefore, when the engine 1 enters the operating state and the supercharger 27 is not operating, the first PCV valve 88 operates as follows. That is, intake negative pressure acts on the valve chamber 77 of the first PCV valve 88 from the intake passage 21 through the reduction passage 32. The blow-by gas filled in the crank chamber 7 of the engine 1 enters the valve chamber 77 from the inlet port 91 and the hollow portion 90 of the valve block 87 through the inlet 78 of the first PCV valve 88, and the pressure of the gas is reduced to the valve pressure. Acts on the body 89. At this time, the intake negative pressure acts on the valve body 89 against the urging force of the spring 81, and the gas pressure acts on the valve body 89, so that the valve body 89 moves toward the valve seat 80, and the valve The size of the flow path opening area (opening) between the seat 80 and the valve body 89 changes. As a result, the blow-by gas flow rate from the valve chamber 77 to the hollow portion 79, that is, measured by the first PCV valve 88, is adjusted.

  On the other hand, in a state where the supercharger 27 is operated, the supercharging pressure acts on the valve chamber 77 of the first PCV valve 88, so that the valve body 89 is pushed and the inlet 78 is closed by the flange 89b. Thereby, the backflow of the high pressure gas from the first PCV valve 88 to the hollow portion 90 is blocked. That is, at this time, the first PCV valve 88 exhibits the same function as the check valve 55 of each of the embodiments. At this time, the second PCV valve 64 functions in the same manner as in the third embodiment, and the blow-by gas that has entered the hollow portion 90 of the valve block 87 from the crank chamber 7 becomes the second PCV valve 64 and The air flows through the second reduction passage 63 to the intake passage 21 upstream of the supercharger 27.

  Therefore, according to the blow-by gas reduction device of this embodiment, it is possible to obtain basically the same effects as those of the third embodiment. In addition, in this embodiment, since the first PCV valve 88 has a simple configuration in which the position of the valve body 89 is variable by pressure, the configuration of the apparatus can be simplified accordingly.

[Fifth Embodiment]
Next, a fifth embodiment of the engine blow-by gas reduction device according to the present invention will be described in detail with reference to the drawings.

  7 and 8 are schematic sectional views of the check valve 96 of this embodiment. This embodiment is different from the first to third embodiments in that a plate type check valve 96 is provided in place of the ball type check valve. As shown in FIGS. 7 and 8, the check valve 96 of this embodiment includes a plate-like base 98 fixedly provided in a passage 97, and a plate supported so as to be movable in the axial direction with respect to the base 98. And a stopper 100 that is fixed to the passage 97 on the downstream side of the base 98 and restricts the movement of the valve body 99. The base 98 includes a boss 98a formed at the center, a plurality of vent holes 98b formed around the boss 98a, and an annular rib 98c projecting around the vent hole 98b on the downstream side surface of the base 98. Is provided. The valve body 99 includes a plate-like main body 99a and a support shaft 99b extending from the main body 99a. The valve body 99 is slidably supported with respect to the boss 98a via the support shaft 99b. The stopper 100 is formed, for example, in a cross frame shape in a plan view, and allows gas to pass through a gap between the frames.

  According to the check valve 96 of this embodiment described above, as shown in FIG. 7, when blow-by gas flows through the passage 97 in the forward direction, the valve body 99 is caused by the pressure of the blow-by gas passing through the vent hole 98b of the base 98. Is pushed, and the pushed valve body 99 hits the stopper 100 and is stopped. At this time, the blow-by gas passing through the vent hole 98 b flows downstream between the rib 98 c and the valve body 99 and between the valve body 99 and the stopper 100. On the other hand, as shown in FIG. 8, when the high-pressure gas tries to flow backward through the passage 97, the valve body 96 is pushed by the high-pressure gas and comes into contact with the rib 98c. In this state, the gap between the rib 98c and the valve body 99 is sealed, and the passage of the high-pressure gas is stopped. Thereby, the backflow of the high pressure gas in the passage 97 can be prevented.

[Sixth Embodiment]
Next, a sixth embodiment of the engine blow-by gas reduction device according to the present invention will be described in detail with reference to the drawings.

  9 to 11 are sectional views of the PCV valve 100 of this embodiment. This embodiment differs from the PCV valve 33 of the first embodiment in the positional relationship between the valve body 102 of the PCV valve 100 and the ball 112 of the check valve 104.

  Also in this embodiment, the PCV valve 100 makes the flow path opening area by the valve body 102 variable by making the position of the valve body 102 variable by electromagnetic force. That is, as shown in FIG. 9, the PCV valve 100 generally includes a valve seat 101, a valve body 102, a step motor 103 for moving the valve body 102 by electromagnetic force, and an intake passage 21. A ball-type check valve 104 corresponding to the suppression valve of the present invention for suppressing the backflow of gas, and a housing 105 that houses the valve seat 101, the valve body 102, the step motor 103, and the check valve 104 are provided. The PCV valve 100 is operated by energizing the step motor 103 to change the position of the valve body 102 with respect to the valve seat 101, so that the size of the blow-by gas passage between the valve seat 101 and the valve body 102, that is, The flow passage opening area of the blow-by gas is variable, and the blow-by gas flow rate measured by the PCV valve 100 is adjusted.

  In this embodiment, the housing 105 has a hollow shape and includes a first housing 106, a second housing 107, and a third housing 108 which are divided into three. The first to third housings 106 to 108 are each molded from resin. The first housing 106 includes a hollow portion 106a formed therein and an inlet side pipe joint 106b formed in the lower portion thereof. The inlet side pipe joint 106b includes an inlet port 106c communicating with the hollow portion 106a, and a seal ring 109 is attached to the outer periphery thereof. A valve chamber 110 is configured by the majority of the hollow portion 106 a, and the valve body 102 is disposed in the valve chamber 110. An outlet port 106d is formed on the outlet side of the valve chamber 110, and the valve seat 101 is disposed corresponding to the outlet port 106d.

  A step motor 103 is integrally formed in the second housing 107 by insert molding, and a connector portion 107a is formed on the upper portion thereof. The step motor 103 is configured to be covered with a metal motor case 111. The third housing 108 is assembled to the first housing 106 by the base end outer peripheral portion 108 a being press-fitted into the distal end opening 106 e of the first housing 106 and being ultrasonically welded. The third housing 108 includes an outlet-side pipe joint 108b at the tip, and includes a hollow portion 108c inside. The inlet-side joint 106b of the first housing 106 is connected to the oil separator 31 and receives the blow-by gas from the crank chamber 7 in the inlet port 106c. One end of a reduction passage 32 communicating with the intake passage 21 of the engine is connected to the outlet side pipe joint 108b of the third housing 108. In this embodiment, the inlet port 106c, the valve chamber 110 and the outlet port 106d of the first housing 106, and the hollow portion 8c of the third housing 108 constitute a blow-by gas passage through which blow-by gas flows.

  In this embodiment, in the first housing 106, a check valve 04 is provided between the outlet port 106d and the tip opening 106e. The check valve 104 includes a ball 112, a holding plate 113 for the ball 112, and a spring 114 that urges the ball 112 in the valve opening direction. The ball 112 and the holding plate 113 are accommodated in a valve chamber 106f formed adjacent to the outlet port 106d, and the spring 114 is accommodated in the outlet port 106d. The ball 112 opens and closes the outlet port 106d in the valve chamber 106f. The holding plate 113 is formed with a large number of slits that allow the passage of gas. The check valve 104 is closed to prevent backflow of high-pressure gas from the intake passage 21 through the reduction passage 32 to the hollow portion 108 c of the third housing 108. By closing the check valve 104, it is possible to prevent the high pressure gas from flowing back from the PCV valve 100 to the crank chamber 7 of the engine.

  In addition to the motor case 111, the step motor 103 includes a stator 115 that generates electromagnetic force, and a rotor 117 that is provided integrally with the output shaft 116 at the center of the stator 115. A valve body 102 is provided at the tip of the output shaft 116. The output shaft 116 and the valve body 102 are connected by screwing a screw 116 a formed on the outer periphery of the output shaft 116 into a screw hole 102 a formed in the valve body 102. Therefore, when the output shaft 116 rotates, the valve body 102 moves in the axial direction due to the relationship between the screw 116a and the screw hole 102a. The moving direction of the valve body 102 is determined by the difference in the rotation direction (forward rotation / reverse rotation) of the output shaft 116. The distal end portion of the external terminal 118 extending from the stator 115 is disposed in the connector portion 107a.

  The tip of the valve body 102 has a truncated cone shape. The valve seat 101 has an annular shape and has a valve hole 101a in the center. The tip of the valve body 102 is provided so as to be able to penetrate the valve hole 101a of the valve seat 101. In this embodiment, the output shaft 116 and the valve body 102 of the step motor 103 are made of a metal such as aluminum. Therefore, the step motor 103 and the valve body 102 are thermally connected by the metal output shaft 116 having better thermal conductivity than the resin housing 105. As a result, heat generated in the step motor 103 is transmitted to the valve body 102 via the output shaft 116.

  In this embodiment, a cover member 119 is provided so as to enclose the valve body 102 in the valve chamber 110. The cover member 119 has a substantially cylindrical shape, and has a hole 119a formed at the distal end and a flange 119b formed at the proximal end. The valve body 102 is provided in the hole 119a so as to be able to pass therethrough. The cover member 119 is formed of a metal such as aluminum as a member having better thermal conductivity than the housing 105. The cover member 119 is provided such that its flange 119 b is in contact with the end surface of the motor case 111 of the step motor 103. The flange 119b of the cover member 119 is caulked to the end surface of the motor case 111 and fixed. Thereby, the cover member 119 and the motor case 111 are integrally provided. A flange 102 b is formed at the proximal end of the valve body 102. In the cover member 119, a compression spring 120 is interposed between the inner wall at the tip and the flange 102 b of the valve body 102. The valve body 102 is urged by the spring 120 in a direction away from the valve seat 101. In this embodiment, the cover member 119 is made of a material having better heat conductivity than the housing 105, and the cover member 119 is provided to be exposed to the valve chamber 110 constituting the blow-by gas passage. Further, the flange 119b of the cover member 119 is in contact with the motor case 111, so that both the members 119 and 111 are thermally connected.

  In this embodiment, an assembly including the valve body 102, the step motor 103, the second housing 107, the cover member 119, and the spring 120 press-fits the cover member 119 into the hollow portion 106 a of the first housing 106, The bonding surface with the second housing 107 is ultrasonically welded to the first housing 106.

  Here, the positional relationship between the valve body 102 of the PCV valve 100 and the ball 112 of the check valve 104 will be described. FIG. 9 shows a state in which the ball 112 of the check valve 104 is opened away from the outlet port 106d, and a state in which the valve body 102 of the PCV valve 100 is opened away from the valve seat 101. In this state, the ball 112 of the check valve 104 and the valve body 102 of the PCV valve 112 are separated from each other. Thus, the state in which the ball 112 is separated from the outlet port 106d indicates a normal initial state in which the ball 112 is pushed by the spring 114 and opened. From this initial state, the high pressure gas flows back into the hollow portion 108c of the third housing 108, whereby the ball 112 is pushed by the high pressure gas against the spring 114 to close the outlet port 106d, and the check valve 104 is closed. It becomes a state. By closing the valve in this way, it is possible to prevent the backflow of the high-pressure gas from the PCV valve 100 to the crank chamber 7. On the other hand, even if the valve body 102 of the PCV valve 100 moves from the state shown in FIG. 9 and contacts the valve seat 101 as shown in FIG. 10, the valve body 102 collides with the ball 112. The valve body 102 is configured to function normally. Here, in this embodiment, as shown by the solid line in FIG. 11, when the check valve 104 is closed, that is, when the ball 112 is in contact with the outlet port 106d, the ball 112 and the valve body 102 are When the valve 102 is in contact with the valve seat 101 and closes, it is provided at a position where it collides with each other. The reason why the valve body 102 can collide with the ball 112 in the valve closed state in this way is that the ball 112 is stuck to the periphery of the outlet port 106d in the valve closed state and does not operate normally. This is to prevent it.

  Therefore, according to the blow-by gas reduction device of this embodiment, basically the same operational effects as those of the first embodiment can be obtained. In addition, according to the PCV valve 100 of this embodiment, as shown by a solid line in FIG. 11, the ball 112 of the check valve 104 is stuck or bitten by the peripheral edge of the outlet port 106d in the closed state. However, when the valve body 102 of the PCV valve 100 is closed, the ball 112 and the valve body 102 collide with each other, and the fixed state of the ball 112 is forcibly released as shown by a two-dot chain line in FIG. It becomes. As a result, malfunction due to sticking of the check valve 104 or the like can be prevented. For this reason, it is possible to prevent the blow-by gas from flowing into the reduction passage 32 due to the PCV valve 100 being closed due to the malfunction of the check valve 104. As a result, it is possible to prevent the blow-by gas in the crank chamber 7 from flowing back to the intake passage 21 through the vent hole 35 and the fresh air passage 34, depositing in the intake passage 21, and deterioration of engine oil. it can.

  Here, under the condition in which the PCV valve 100 is normally used, the valve body 102 does not collide with the ball 112 of the check valve 104. Therefore, in this embodiment, in the unlikely event that a malfunction occurs due to the check valve 104 being stuck or the like, the valve body 102 of the PCV valve 100 is once closed every time the engine 1 is started in order to forcibly release it. It is supposed to make a valve.

  The present invention is not limited to the embodiments described above, and can be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention.

  (1) Although the check valve 55 is provided integrally with the PCV valves 33, 61, 62 in the first to third embodiments, the check valve may be provided separately from the PCV valve. For example, a check valve may be provided in the middle of a pipe constituting the reduction passage.

  (2) In the first and second embodiments, the blow-by gas reduction device of the present invention is embodied for the engine 1 provided with the supercharger 27. However, the blow-by gas of the present invention is used for an engine not provided with the supercharger. A reduction device can also be embodied.

The schematic block diagram which shows the gasoline engine system which concerns on 1st Embodiment and contains a blow-by gas reduction apparatus. Sectional drawing which concerns on 1st Embodiment and shows a PCV valve | bulb. Sectional drawing which concerns on 2nd Embodiment and shows a PCV valve | bulb. The schematic block diagram which concerns on 3rd Embodiment and shows the gasoline engine system containing a blow-by gas reduction apparatus. Sectional drawing which concerns on 3rd Embodiment and shows a PCV valve | bulb. Sectional drawing which concerns on 4th Embodiment and shows a composite PCV valve | bulb. Sectional drawing which concerns on 5th Embodiment and shows a non-return valve. Sectional drawing which concerns on 5th Embodiment and shows a non-return valve. Sectional drawing which concerns on 6th Embodiment and shows a PCV valve | bulb. Sectional drawing which concerns on 6th Embodiment and shows a PCV valve | bulb. Sectional drawing which concerns on 6th Embodiment and shows a PCV valve | bulb.

Explanation of symbols

1 Engine 2 Combustion chamber 3a Crankcase 7 Crank chamber 21 Intake passage 27 Supercharger 28 Compressor 29 Turbine 32 Reduction passage 32a Opening 33 PCV valve 34 Fresh air passage 34a Inlet 35 Vent hole 41 Valve body 55 Check valve 61 PCV valve 62 First PCV valve 63 Second reduction passage 64 Second PCV valve 76 Valve body 88 First PCV valve 89 Valve body 96 Check valve 100 PCV valve 102 Valve body 104 Check valve 112 Ball

Claims (8)

The blow-by gas leaked from the engine combustion chamber into the crankcase flows into the intake passage through the reduction passage and is reduced to the combustion chamber, and the blow-by gas flow rate is adjusted by the PCV valve provided in the reduction passage. In the engine blow-by gas reduction device,
The PCV valve is configured to change the flow path opening area by changing the position of the valve body by electromagnetic force, and in the reduction passage between the crankcase and the valve body of the PCV valve, A blow-by gas reduction device for an engine, comprising a suppression valve for suppressing a backflow of gas from the intake passage. The blow-by gas leaked from the engine combustion chamber into the crankcase flows into the intake passage through the reduction passage and is reduced to the combustion chamber, and the blow-by gas flow rate is adjusted by the PCV valve provided in the reduction passage. In the engine blow-by gas reduction device,
The PCV valve is configured to change the flow path opening area by changing the position of the valve body by electromagnetic force. In the reduction passage between the valve body of the PCV valve and the intake passage, A blow-by gas reduction device for an engine, comprising a suppression valve for suppressing a backflow of gas from the intake passage. The blow-by of an engine according to claim 2, wherein the suppression valve and the valve body are provided at a position where they collide with each other when the valve body is closed when the suppression valve is in a closed state. Gas reduction device. A supercharger for boosting the intake air is provided upstream of the opening of the reduction passage in the intake passage, one end communicates with the reduction passage between the suppression valve and the crankcase, and the other end is the excess passage. A second reduction passage that communicates with the intake passage on the upstream side of the feeder is provided, and a second PCV valve is provided in the second reduction passage, and the second PCV valve 4. The blow-by gas reduction device for an engine according to claim 1, wherein the flow path opening area is variable by changing the position. The fresh air passage for introducing fresh air is provided in the crankcase, and an inlet of the fresh air passage communicates with a downstream side of the supercharger in the intake passage. Engine blow-by gas reduction device. 6. The engine according to claim 4, wherein the second PCV valve has a larger flow path opening area as a difference in pressure between the upstream side and the downstream side of the second PCV valve is larger. Blow-by gas reduction device. The blow-by gas leaked from the engine combustion chamber into the crankcase flows into the intake passage through the reduction passage and is reduced to the combustion chamber, and the blow-by gas flow rate is adjusted by the PCV valve provided in the reduction passage. In the engine blow-by gas reduction device,
A supercharger is provided in the intake passage;
The PCV valve has a variable flow path opening area by changing the position of the valve body by pressure,
The reduction passage has one end communicating with the crankcase and the other end communicating with the intake passage on the downstream side of the supercharger;
A suppression valve provided in the reduction passage for suppressing the flow of gas from the intake passage;
A second reduction passage whose one end communicates with the reduction passage between the suppression valve and the crankcase and the other end communicates with the intake passage upstream of the supercharger;
A second PCV valve provided in the second reduction passage;
The second PCV valve is configured to change a flow path opening area by changing a position of a valve body by pressure, and the second PCV valve is configured to change the second PCV valve. The blow-by gas reduction device for an engine is characterized in that the flow path opening area increases as the difference in pressure between the upstream side and the downstream side increases. The fresh air passage for introducing fresh air is provided in the crankcase, and an inlet of the fresh air passage communicates with a downstream side of the supercharger in the intake passage. Engine blow-by gas reduction device.

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