JP2009174334A - Pcv system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce accumulation of blow-by gas in a crank case in an internal combustion engine provided with a supercharger. <P>SOLUTION: A PCV system 1 for an internal combustion engine is provided with; an internal combustion engine 100; a cover part 25 sealing a case inside space in a crankcase 5; a discharge means 10 provided at the cover part, opening according to pressure rise in the case inside space formed by movement of a piston 4 in a cylinder 23 toward the case inside space, and discharging blow-by gas from the case inside space; a first channel part 43 re-circulating the discharger blow-by gas to a downstream of the supercharger at an intake side of the internal combustion engine; a second channel part 44 re-circulating the discharged blow-by gas to an upstream of the supercharger in an intake side of the internal combustion engine; and a pump 50 provided in a middle or at an end of the second channel part and facilitating recirculation of the discharged blow-by gas. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technical field of a PCV (Positive Crankcase Ventilation) system of an internal combustion engine which is an example of a blow-by gas reduction device provided in an internal combustion engine such as an engine.

  In this type of PCV system, blow-by gas generated during combustion in an internal combustion engine and accumulated in a crankcase is circulated to the intake side (see Patent Document 1). Various techniques have been proposed in order to efficiently recirculate such blow-by gas.

For example, Patent Document 2 proposes a technique in which blow-by gas accumulated in a crankcase is sucked by a pump. Patent Documents 3 to 5 propose a technique of adjusting the amount of blow-by gas that recirculates according to the concentration of NOx and the load of the internal combustion engine.
Japanese Utility Model Publication No. 5-87213 JP 2001-164918 A JP 2006-183641 A JP 2006-138242 A JP 7-158539 A

  However, in an internal combustion engine equipped with a supercharger, the pressure on the intake side of the internal combustion engine becomes high at high loads when intake by the supercharger is performed, and it becomes difficult to recirculate blow-by gas. Therefore, there is a technical problem that the amount of blow-by gas accumulated in the crankcase increases, resulting in an increase in oil consumption. Furthermore, there is a technical problem that a device that operates by hydraulic pressure may not function normally because oil supply is not performed properly.

  The present invention has been made in view of the above-described problems, for example, and an object thereof is to provide a PCV system for an internal combustion engine capable of efficiently recirculating blowby gas accumulated in a crankcase.

  In order to solve the above problems, the PCV system for an internal combustion engine of the present invention has (i) a cylinder, (ii) a crankcase, (iii) a supercharger for taking in air into the cylinder, and (iv) in the cylinder. An internal combustion engine having a piston that reciprocates in the cylinder according to the combustion of fuel, a cover portion that seals the case inner space in the crankcase, and the cover portion, the piston being provided in the case inner space Opening in response to an increase in pressure in the case internal space caused by moving in the cylinder toward the exhaust, and a discharge means for discharging blowby gas from the internal space of the case; A first flow path portion that circulates downstream of the supercharger on the intake side of the engine, and the exhaust when the downstream pressure is not negative. A second flow path portion that recirculates the blowby gas upstream of the supercharger on the intake side of the internal combustion engine, and a recirculation of the discharged blowby gas provided in the middle or end of the second flow path portion. And a pump for promoting the operation.

  According to the PCV system for an internal combustion engine of the present invention, the internal combustion engine is, for example, an engine mounted on a vehicle, and a piston reciprocates in the cylinder according to the combustion of fuel in the cylinder, and the driving force of the vehicle is increased. generate.

  The cover portion is provided so as to seal a space in the case inside the crankcase, more specifically, a space in which a rotating shaft for rotating the crankshaft is housed. It is separated.

  The discharge means is provided in the cover part, and, for example, by the operation of the piston when the fuel burns in the combustion chamber in the cylinder, in other words, the piston moves in the cylinder toward the space in the case. It opens according to the pressure rise in the space in the case caused by this. Such discharge means is a one-way valve such as a reed valve that opens in response to an increase in the pressure in the case space, or when the pressure in the space in the case is higher than the pressure in the outer space, These are various valve mechanisms such as a valve for communicating the outer space with each other. The discharge means may be configured to passively open and close by the pressure in this way. Alternatively, for example, an open / close operation may be actively performed by an actuator or the like under the control of an ECU (Electronic Control Unit) or a microcomputer or processor provided in the ECU.

  Therefore, according to such discharge means, blow-by gas introduced from the combustion chamber through the piston ring and the ring groove to the space in the case out of the blow-by gas generated by the combustion of the fuel to the space outside the space in the case. The amount of blow-by gas accumulated in the space inside the case can be reduced. Since the blow-by gas accumulated in the case inner space can be reduced in this way, the oil connected to the piston and pulled up from the oil pan to the case inner space according to the operation of the connecting rod driven in accordance with the operation of the piston. The amount of oil mixed with blow-by gas can be reduced. Therefore, for example, the maintenance pitch of engine oil can be reduced and the running cost of the engine can be reduced.

  In the present invention, further, the blow-by gas discharged from the space in the case by the discharge means is returned to the downstream of the supercharger on the intake side of the internal combustion engine by the first flow path portion. Accordingly, the discharged blow-by gas is guided to the internal combustion engine and recombusted. Thus, by recombusting the blow-by gas, it is possible to reduce harmful substances such as HC (hydrocarbon) in the exhaust gas, for example.

  Here, the pressure downstream of the supercharger described above may not be a negative pressure, for example, during high-load operation of the supercharger. That is, the pressure downstream of the supercharger may be higher than the pressure in the case space. If the pressure downstream of the supercharger is no longer negative, it will be difficult to recirculate the exhausted blow-by gas through the first flow path.

  In such a case, the discharged blow-by gas is returned to the upstream of the supercharger by the second flow path portion. That is, the discharged blow-by gas is returned to different positions in different flow passages depending on whether or not the pressure downstream of the supercharger is negative. Thereby, it becomes possible to recirculate the discharged blow-by gas regardless of the pressure downstream of the supercharger.

  In the present invention, in particular, a pump is provided in the middle or at the end of the second flow path portion to promote the reflux of blow-by gas by the second flow path portion. Specifically, the discharged blow-by gas is sucked by a pump and discharged to the downstream side of the second flow path portion. The pump appropriately performs a suction operation under the control of a control unit such as an ECU. Thereby, for example, even when the negative pressure is not high enough to allow the upstream of the supercharger to perform the reflux, the efficient reflux can be performed. Further, since the blow-by gas existing in the crankcase when the discharge means is open is also sucked by the pump, the blow-by gas is sufficiently discharged by the discharge means by, for example, shifting the opening / closing timing of the discharge means. Emissions can also be promoted if not done.

  As described above, according to the PCV system of the internal combustion engine of the present invention, since the first flow path portion and the second flow path portion provided with the pump are provided, the blow-by gas can be recirculated suitably. In addition, since the amount of oil mixed with the blow-by gas can be reduced by the discharge means, it is possible to reduce the recirculated blow-by gas from adhering to the inside of the supercharger and the intake system, resulting in malfunction of the supercharger. And the throttle valve sticking can be suppressed. Therefore, it is possible to suppress a decrease in operating performance of an internal combustion engine such as an engine.

  In one aspect of the PCV system for an internal combustion engine of the present invention, the internal combustion engine further includes a reflux control valve that is provided on the downstream side of the pump in the second flow path portion and controls the flow rate of the refluxed blowby gas.

  According to this aspect, the recirculation control valve is provided on the downstream side of the pump in the second flow path portion, and the flow rate of the blow-by gas recirculated by the second flow path portion is controlled by adjusting the opening degree. It is possible. Note that the opening degree of the reflux control valve is typically automatically adjusted according to various conditions in the system. The reflux control valve may be configured to open / close the flow path or adjust the opening degree by an actuator that rotates the valve body or the valve shaft of the reflux control valve under the control of a control means such as an ECU, for example. Good.

  In the second flow path portion, for example, the blow-by gas is forced to recirculate by the pump regardless of the pressure on the upstream side of the supercharger, and therefore, the blow-by gas exceeding the flow rate to be recirculated may be recirculated. . In such a case, if a reflux control valve is used, it becomes possible to recirculate blow-by gas having a desired flow rate by adjusting the opening degree. That is, according to the PCV system of the internal combustion engine according to this aspect, it is possible to recirculate blowby gas more suitably.

  In the aspect including the above-described recirculation control valve, the recirculation control valve is configured to be opened and closed so as not to recirculate the discharged blow-by gas when intake by the supercharger is performed. Also good.

  According to this configuration, when intake by the supercharger is being performed, the return control valve is closed under the control of a control unit such as an ECU, and the blow-by returned to the second flow path unit The gas is controlled not to be released upstream of the supercharger. Thereby, it is possible to prevent the refluxed blowby gas from being mixed with fresh air upstream of the supercharger. If the refluxed blowby gas and fresh air are mixed, oil consumption in the internal combustion engine increases. Therefore, as described above, oil consumption in the internal combustion engine can be reduced by preventing the refluxed blow-by gas and fresh air from mixing.

  In the aspect including the above-described reflux control valve, the pressure detection unit that detects the downstream pressure and the determination unit that determines whether or not intake by the supercharger is performed based on the detected pressure. The reflux control valve may be configured to control the flow rate based on the determination.

  If comprised in this way, at the time of operation | movement of an internal combustion engine, the pressure downstream of a supercharger will be detected by a pressure detection means first. Subsequently, for example, a determination unit configured by an ECU or the like determines whether intake by the supercharger is performed based on the detected pressure. Specifically, for example, when a predetermined threshold value for pressure is set in advance and the detected pressure exceeds the predetermined threshold value, it is determined that intake by the supercharger is being performed. Based on the detected pressure, the determination unit can more easily determine whether or not intake by the supercharger is being performed.

  The reflux control valve is controlled based on the determination by the determination unit described above. That is, the flow rate of the blow-by gas recirculated by the second flow path part is controlled based on the determination by the determination unit. For example, when the determination means determines that intake by the supercharger is being performed, the recirculation control valve is controlled in the closing direction, and the flow rate of the recirculating blowby gas is reduced. Thus, the reflux control valve can be more easily controlled by adjusting the opening based on the determination by the determination means. Therefore, it is possible to recirculate blowby gas more suitably.

  In the aspect including the above-described recirculation control valve, the recirculation control valve further includes first concentration detection means for detecting the concentration of NOx on the exhaust side of the internal combustion engine, and the recirculation control valve includes the NOx concentration detected by the first concentration detection means. The flow rate may be controlled based on the concentration.

  If comprised in this way, at the time of operation | movement of an internal combustion engine, the density | concentration of NOx (nitrogen oxide) in the exhaust side of an internal combustion engine will be detected first by the 1st density | concentration means including a concentration sensor first. Then, based on the NOx concentration detected by the first concentration detecting means, the opening degree of the reflux control valve is adjusted, and the flow rate of the blow-by gas flowing back through the second flow path part is controlled. For example, a predetermined threshold value for the NOx concentration is set in advance, and when the detected NOx concentration exceeds the predetermined threshold value, the reflux control valve is controlled to close.

  Here, the NOx concentration on the exhaust side of the internal combustion engine and the NOx concentration in the blow-by gas in the crankcase have a very strong correlation. For this reason, controlling the flow rate of the recirculating blowby gas based on the NOx concentration on the exhaust side of the internal combustion engine controls the flow rate of the recirculating blowby gas based on the NOx concentration in the blowby gas in the crankcase. It can be said that it is substantially the same.

  Therefore, if the flow rate of the recirculating blowby gas is controlled based on the NOx concentration on the exhaust side of the internal combustion engine, the blowby gas having a high NOx concentration is recirculated from within the crankcase, so that the blowby gas accumulated in the internal combustion engine is recirculated. It is possible to prevent the NOx concentration in the inside from becoming too high. Therefore, for example, it can be prevented that NOx reacts with oil and the oil is rapidly deteriorated. Further, it is possible to prevent the combustion in the internal combustion engine from deteriorating when the blow-by gas is recirculated and recombusted. That is, it is possible to recirculate the blow-by gas while avoiding the adverse effects that occur due to the high NOx concentration in the blow-by gas.

  In the aspect provided with the above-described reflux control valve, it further comprises second concentration detection means for detecting the NOx concentration in the crankcase, and the reflux control valve is based on the NOx concentration detected by the second concentration detection means. The flow rate may be controlled.

  If comprised in this way, at the time of operation | movement of an internal combustion engine, the density | concentration of NOx (nitrogen oxide) in a crankcase is first detected by the 2nd density | concentration means which contains a concentration sensor first. Then, based on the NOx concentration detected by the second concentration detecting means, the opening degree of the reflux control valve is adjusted, and the flow rate of the blow-by gas flowing back through the second flow path portion is controlled. For example, a predetermined threshold value for the NOx concentration is set in advance, and when the detected NOx concentration exceeds the predetermined threshold value, the reflux control valve is controlled to close.

  If the flow rate of the recirculating blowby gas is controlled based on the NOx concentration in the crankcase, the NOx concentration in the blowby gas accumulated in the internal combustion engine is recirculated from the crankcase when the blowby gas having a high NOx concentration is recirculated. Can be prevented from becoming too high. Therefore, for example, it can be prevented that NOx reacts with oil and the oil is rapidly deteriorated. Further, it is possible to prevent the combustion in the internal combustion engine from deteriorating when the blow-by gas is recirculated and recombusted. That is, it is possible to recirculate the blow-by gas while avoiding the adverse effects that occur due to the high NOx concentration in the blow-by gas.

  In addition to the second concentration detection means, when the first concentration detection means described above is provided, the NOx concentration detected by the first and second concentration detection means is comprehensively taken into consideration, and the reflux control valve You may make it control opening and closing. That is, the opening / closing of the reflux control valve may be controlled based on both the NOx concentration on the exhaust side of the internal combustion engine and the NOx concentration in the crankcase. This can more effectively prevent the NOx concentration in the blow-by gas from becoming too high.

  In another aspect of the PCV system for an internal combustion engine of the present invention, a gas flow path that flows from the upstream side of the recirculation position by the second flow path portion upstream of the supercharger to the cylinder head of the cylinder is configured. A third flow path section, a first one-way valve provided in the third flow path section, a fourth flow path section constituting a flow path of gas flowing from the downstream of the supercharger to the cylinder head, An adjustment valve is provided downstream of the supercharger and between the fourth flow path portions and adjusts the amount of gas flowing to the cylinder head by the fourth flow path portions.

  According to this aspect, gas is introduced into the cylinder head from the upstream side of the supercharger by the third flow path portion. In particular, the third flow path section introduces gas from the upstream side of the recirculation position by the second flow path section upstream of the supercharger, so that it is not mixed with the blow-by gas recirculated by the second flow path section. It is possible to introduce qi. Further, since the first one-way valve is provided in the third flow path portion, it is possible to prevent the fresh air introduced into the cylinder head from flowing backward. In addition, typically, when the introduction of fresh air by the supercharger is not performed, the introduction of fresh air by the third flow path portion is performed.

  In the present aspect, gas is further introduced into the cylinder head from the downstream side of the supercharger by the fourth flow path portion. An adjustment valve is provided in the fourth flow path portion, and the amount of gas introduced into the cylinder head is adjusted by the fourth flow path portion by controlling the opening of the adjustment valve. The regulator valve is typically opened when fresh air is introduced downstream of the supercharger. Thereby, fresh air can be introduced into the cylinder head.

  As described above, according to the PCV system for an internal combustion engine according to this aspect, it is possible to reliably introduce fresh air to the cylinder head of the internal combustion engine.

  In another aspect of the PCV system for an internal combustion engine of the present invention, the internal combustion engine further includes a second one-way valve provided downstream of the pump in the second flow path portion.

  According to this aspect, since the second one-way valve is provided on the downstream side of the pump in the second flow path part, the blow-by gas recirculated by the second flow path part flows backward. Can be prevented.

  When the above-described reflux control valve is provided, the second one-way valve is provided on the upstream side (that is, the pump side) from the reflux control valve. Thereby, for example, by closing the reflux control valve, it is possible to prevent the blow-by gas being refluxed from flowing back to the crankcase or the like even when the pressure in the second flow path portion is increased. .

  In another aspect of the PCV system for an internal combustion engine of the present invention, an oil separator is provided between the discharge means and the first and second flow path portions, and separates the blow-by gas and oil from each other. In addition.

  According to this aspect, the blow-by gas discharged by the discharge means is separated from the oil by the oil separator before being refluxed by the first flow path part or the second flow path part. For this reason, the amount of oil contained in the blow-by gas to be refluxed is reduced. Therefore, it is possible to reduce the recirculated blowby gas from adhering to the inside of the supercharger and the intake system, thereby reducing the malfunction of the supercharger and suppressing the sticking of the throttle valve. Therefore, it is possible to suppress a decrease in the operating performance of the internal combustion engine.

  In another aspect of the PCV system for an internal combustion engine of the present invention, an air cleaner is further provided upstream of the recirculation position by the second flow path portion upstream of the supercharger.

  According to this aspect, fresh air taken into the internal combustion engine is introduced through the air cleaner upstream of the supercharging. Therefore, dust or the like contained in the fresh air is adsorbed by the air cleaner and can be introduced into the internal combustion engine after mixing with the blow-by gas that is recirculated into the clean fresh air. Therefore, it is possible to suppress a decrease in the operating performance of the internal combustion engine.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
First, the overall configuration of the PCV system according to the first embodiment will be described with reference to FIG. FIG. 1 is a schematic structural diagram schematically showing the configuration of the PCV system according to the first embodiment. In addition, in FIG. 1, when the supercharger mentioned later operate | moves and the pressure in the flow path part of the downstream of a slot valve is a negative pressure (namely, at the time of low load), each flow path part etc. The flow of the gas flowing through is indicated by a black arrow, and the flow of the gas flowing through each flow path portion at the time of high load is indicated by a white arrow.

  In FIG. 1, the PCV system 1 according to the first embodiment reciprocates in a cylinder 23 according to combustion of fuel in a cylinder 23, a crankcase 5, a supercharger 3 that sucks air into the cylinder 23, and fuel in the cylinder 23. An internal combustion engine 100 having a piston 4; a cover portion 25 for sealing a case inner space 5a in the crankcase 5; a reed valve 10 as an example of the “discharge means” of the present invention provided in the cover portion 25; The oil pan 9 disposed under the portion 25, the oil separator 6 provided to communicate with the crankcase 5, the first intake passage portion 31, the second intake passage portion 42, and the second intake passage portion 42. The pressure sensor 70, which is an example of the “pressure detection means” of the present invention, the throttle valve 7, the oil separator 6, and the second intake passage 42 below the throttle valve 7. Of the first flow passage portion 43 provided between the flow passage portions 42a occupying the side, the oil separator 6 and the first intake passage portion 31, the second provided between the intake passage portion 31a occupying the downstream side in the middle. Gas flowing between the second flow path 44 and the third flow path 41, the flow path 42a and the cylinder head 22 constituting the flow path of the gas flowing from the middle of the first intake path 31 to the cylinder head 22 of the cylinder 23 An example of the “determination means” of the present invention, a fourth flow path portion 45 constituting the flow path, a first exhaust path portion 46 provided on the exhaust side of the internal combustion engine 100, a second exhaust path portion 47, and the like. An ECU (Electronic Control Unit) 500 is provided.

  The internal combustion engine 100 is an engine mounted on a vehicle, for example, and the piston 4 reciprocates in the cylinder 23 in accordance with the combustion of fuel in the cylinder 23 to generate the driving force of the vehicle.

  The first intake passage portion 31 is provided upstream of the supercharger 3, and is an intake passage portion through which air taken from the outside of the internal combustion engine 100 via the air cleaner 2 flows toward the supercharger 3. The second intake passage portion 42 is provided on the downstream side of the supercharger 3, and is an intake passage portion that allows air introduced into the supercharger 3 to flow to the cylinder head 22. That is, during operation of the internal combustion engine 100, the air taken in by the first intake passage portion is compressed in the supercharger 3, and the compressed air is supplied to the cylinder head 22 through the second intake passage portion 42.

  The throttle valve 7 is provided in the middle of the second intake passage portion 42, and is opened and closed according to the operation of the accelerator pedal by the driver, so that the amount of air supplied to the cylinder head 22 can be changed. A pressure sensor 70 is provided upstream of the throttle valve 7 in the second intake passage portion 42, and the pressure inside the second intake passage portion 42 can be detected.

  The cover portion 25 is provided so as to seal a case inner space 5a in the crankcase 5, more specifically, a space in which a rotation shaft for rotating a crankshaft (not shown) is housed. 5a and its outer space are separated from each other.

  The reed valve 10 provided in the cover portion 25 is configured to discharge the blow-by gas accumulated in the crankcase 5 and guide it to the oil separator 6. The detailed configuration and operation of the reed valve will be described in detail later.

  The oil separator 6 is provided so as to communicate with the crankcase 5 and separates blow-by gas and oil discharged by the reed valve 10 from each other. The blow-by gas separated from the oil is supplied to the first flow path portion 43 or the second flow path portion 44 according to the operation of the supercharger 3. The oil separator 6 is provided with a one-way valve 11 to reduce the backflow of blow-by gas from the first flow path portion 43 to the oil separator 6.

  The first flow path portion 43 constitutes a flow path for gas flowing from the oil separator 6 to the flow path portion 42a occupying the downstream side of the throttle valve 7 in the second intake path portion 42, and the supercharger 3 operates. Reflux blow-by gas at low load when not. The second flow path portion 44 includes a pump 50 provided in the middle thereof and a one-way valve 13 provided on the downstream side of the pump 50. The flow path of the gas which flows into the intake passage part 31a which is a part is comprised. The second flow path unit 44 recirculates the blow-by gas when the turbocharger 3 operates at a high load. That is, depending on whether or not the supercharger 3 is operating, one of the first flow path part 43 and the second flow path part 44 is selected, and the blow-by gas is recirculated.

  A recirculation control valve 60 is provided between the second flow path portion 44 and the intake passage portion 31a, and it is possible to control the flow rate of the recirculating blowby gas by opening and closing. A more detailed description of the reflux of blow-by gas will be described later.

  The third flow path portion 41 includes the one-way valve 14 provided in the middle thereof, and a flow path of gas such as air flowing from the middle of the first intake path portion 31 to the cylinder head 22 of the cylinder 23. This makes it possible to supply air to the cylinder head 22 when the load is low. The fourth flow path portion 45 constitutes a flow path for the gas flowing between the cylinder head 22 and the flow path portion 42 a occupying the downstream side of the throttle valve 7 in the second intake path portion 42 from the oil separator 6. The air can be supplied to the cylinder head 22 at the time of high load.

  The first exhaust passage 46 is provided on the exhaust side of the internal combustion engine 100 on the upstream side of the supercharger 3, and guides the exhaust discharged from the internal combustion engine 100 to the supercharger 3. The first exhaust passage 46 is provided on the downstream side of the supercharger 3, and guides the exhaust guided by the first exhaust passage 46 from the supercharger 3 to the outside.

  The ECU 500 is an example of the “control unit” of the present invention. In addition to determining whether or not intake by the supercharger 3 is performed based on the pressure detected by the pressure sensor 70, the ECU 500 operates the PCV system 1. It is an electronic control unit that controls the whole.

  Next, the operation of the reed valve 10 that discharges blow-by gas from the crankcase 5 will be described in detail with reference to FIG.

  In FIG. 1, during operation of the internal combustion engine 100, air taken in from the upstream side of the air cleaner 2 is a first intake passage portion 31, a supercharger 3, an intercooler 8, a second passage portion 42, and a throttle valve 7. To the combustion chamber 24 in the cylinder 23. Blow-by gas generated by the combustion of fuel in the combustion chamber 24 is guided to the case inner space 5 a located below the piston 4 through the piston ring and the ring groove of the piston 4. The blow-by gas guided to the case inner space 5a is mixed with the oil scattered from the oil pan 9 in the case inner space 5a.

  The blow-by gas accumulated in the case internal space 5a is discharged from the case internal space 5a by the reed valve 10. The reed valve 10 is formed in the case caused by the movement of the piston 4 when the fuel burns in the combustion chamber 24 in the cylinder 23, in other words, the piston 4 moves in the cylinder 23 toward the case inner space 5a. It opens as the pressure in the space 5a increases. According to such a reed valve 10, out of the blowby gas generated by the combustion of fuel, the blowby gas guided from the combustion chamber 24 to the case inner space 5 a through the piston ring and the ring groove is transferred to the case inner space 5 a. It can be suitably discharged into the outer space. Therefore, the amount of blow-by gas accumulated in the case internal space 5a can be reduced.

  By reducing the blow-by gas accumulated in the case internal space 5a, the amount of oil mixed with the blow-by gas in the case internal space 5a can be reduced. That is, the amount of oil mixed with the blow-by gas can be reduced among the oil pulled up from the oil pan 9 to the case internal space 5a according to the operation of the connecting rod driven according to the operation of the piston 4. That is, oil consumption in the internal combustion engine 100 can be reduced.

  Further, according to the PCV system 1 for an internal combustion engine according to the first embodiment, the oil pan 9 is disposed below the cover portion 25, and the crankcase 5 is disposed below the cylinder 23. Therefore, the reed valve 10 that opens only in one direction is closed when the pressure in the case internal space 5a decreases when the piston 4 moves upward in the cylinder 23. More specifically, after the combustion process in the internal combustion engine 100, the piston 4 moves upward in the cylinder during the exhaust process of exhausting the gas generated in the combustion chamber 24. As a result, the pressure in the case internal space 5a decreases, and the reed valve 10 closes in accordance with the decrease in the pressure.

  By closing the reed valve 10 as described above, it is possible to reduce the oil scattering from the oil pan 9 side to the case inner space 5a through the reed valve 10 due to fluctuations in the oil surface. That is, oil consumption can be reduced more effectively. Note that, when the internal combustion engine 100 operates at a high load, the oil surface of the oil pan 9 fluctuates drastically, so that the above-described effects are particularly remarkable.

  As described above, the oil consumption in the internal combustion engine 100 can be effectively reduced by providing the cover portion 25 with the reed valve 10 that discharges blow-by gas. Therefore, for example, the maintenance pitch of engine oil can be reduced and the running cost of the engine can be reduced. In addition, since the amount of oil supplied to the internal combustion engine such as the case internal space 5a is maintained at an appropriate amount, VVT (variable valve mechanism) that is operated by hydraulic pressure, and operation parts such as various valve systems, Appropriate operation is possible up to the high speed region of the internal combustion engine.

  Next, the flow path of the blow-by gas that is recirculated to the respective flow passages according to the operation and non-operation of the supercharger 3 and the operation at that time will be described in detail with reference to FIG. 2 in addition to FIG. FIG. 2 is a flowchart showing the flow of flow control of blow-by gas by the reflux control valve.

  In FIG. 1, blow-by gas accumulated in the crankcase 5 is discharged by the above-described reed valve 10 and then separated into blow-by gas and oil by the oil separator 6. Then, the separated blow-by gas is refluxed by either the first flow path portion 43 or the second flow path portion 44 depending on whether or not the supercharger 3 is operating.

  At low load when intake by the supercharger is not performed, the pressure in the flow path portion 42a is negative. For this reason, the blow-by gas discharged from the oil separator 6 is sucked to the flow path part 42a side. Therefore, the blow-by gas is refluxed by the first flow path portion 43 and introduced into the internal combustion engine 100 via the flow path portion 42a. The blow-by gas recirculated to the internal combustion engine 100 is burned again in the combustion chamber 24. When the load is low, air is supplied from the first intake passage portion 31 via the cylinder head oil separator 21 and the cylinder head 22, so that the ventilation of air and blow-by gas is maintained in a good state in the case inner space 5a. The

  On the other hand, at the time of high load in which intake by the supercharger is performed, the pressure in the flow path portion 42a increases and does not become negative pressure. For this reason, the blow-by gas is recirculated to the intake passage portion 31 a by the second flow path portion 44. The blow-by gas recirculated to the intake passage 31a is guided to the internal combustion engine by the supercharger 3 and burned again in the combustion chamber 24.

  In the present embodiment, in particular, the pump 50 is provided in the second flow path portion 44, and blow-by gas is sucked to promote recirculation by the second flow path portion 44. That is, the blow-by gas to be refluxed can be increased by forcibly flowing the blow-by gas through the second flow path portion 44. Thereby, for example, even when the negative pressure is not high enough to allow the upstream of the supercharger to perform the reflux, the efficient reflux can be performed. Further, since the blow-by gas existing in the crankcase when the discharge means is open is also sucked by the pump, the blow-by gas is sufficiently discharged by the discharge means by, for example, shifting the opening / closing timing of the discharge means. Emissions can also be promoted if not done. A one-way valve 13 is provided on the downstream side of the pump in the second flow path portion 44 to prevent the blow-by gas released from the pump from flowing back to the pump side.

  In the present embodiment, a reflux control valve 60 is further provided between the second flow path portion 44 and the intake passage portion 31a. In the second flow path portion 44, as described above, the blow-by gas is forcibly recirculated by the pump 50, so that the blow-by gas having a flow rate higher than the recirculation amount may be recirculated. In such a case, if the reflux control valve 60 is used, the blow-by gas having a desired flow rate can be refluxed by adjusting the opening degree.

  The recirculation control valve 60 is controlled to be opened at a low load when intake by the supercharger is not performed, for example, and is closed at a high load when intake by the supercharger 3 is performed. That is, the blow-by gas recirculated by the second flow path portion 44 is controlled so as not to be discharged upstream of the supercharger 3 at a high load. Thereby, it is possible to prevent the refluxed blowby gas from being mixed with fresh air upstream of the supercharger 3. If the refluxed blow-by gas and fresh air are mixed, oil consumption in the internal combustion engine 100 increases. Therefore, as described above, oil consumption in the internal combustion engine 100 can be reduced by preventing the refluxed blowby gas and fresh air from mixing.

  Here, whether or not the supercharger 3 is operating, which is a condition for controlling the reflux control valve 60, is determined based on the pressure in the second intake passage portion 42 detected by the pressure sensor 70. Is called.

  In FIG. 2, when the operation of the PCV system 1 for an internal combustion engine according to the first embodiment is started, the pressure sensor 70 first detects the pressure in the second intake passage portion 42 (step S11). The detected pressure is transmitted to the ECU 500, and the ECU 500 determines whether or not intake by the supercharger 3 is performed based on the detected pressure (step S12). Specifically, for example, when a predetermined threshold value for pressure is set in advance and the detected pressure exceeds a predetermined threshold value, it is determined that intake by the supercharger is being performed.

  When it is determined that intake by the supercharger 3 is being performed (step S12: YES), the recirculation control valve 60 is closed, and control is performed so that the recirculated blowby gas is not released into the intake passage 31a ( Step S13). Further, when it is determined that intake by the supercharger 3 is not performed (step S12: NO), the recirculation control valve 60 is opened, and control is performed so that the recirculated blowby gas is discharged to the intake passage portion 31a. (Step S14). The reflux control valve 60 is controlled by repeatedly executing the above-described series of processing (step S11 to step S14).

  As described above, the blow-by gas accumulated in the crankcase 5 is preferably recirculated by the first intake passage portion 43 and the second intake passage portion 44. Therefore, harmful substances in the exhaust can be reduced. In addition, since the oil consumption is reduced by providing the reed valve 10, the blow-by gas blow-by gas flows into the supercharger 3, as well as the first intake passage portion 31, the second intake passage portion 43, the first intake passage portion 43, and the second intake passage portion 43. Adhesion inside the intake system including the first flow path portion 43 and the second flow path portion 44 can be reduced, and the malfunction of the supercharger 3 can be reduced and the throttle valve can be prevented from sticking. Therefore, according to the PCV system 1 according to the first embodiment, it is possible to appropriately recirculate the blow-by gas while suppressing a decrease in the operating performance of the internal combustion engine 100 such as the engine.

Second Embodiment
Next, a PCV system according to the second embodiment will be described with reference to FIGS. FIG. 3 is a schematic structural diagram schematically showing the configuration of the PCV system according to the second embodiment, and FIG. 4 is a flowchart showing the flow of blow-by gas flow control by the recirculation control valve. FIG. 5 is a timing chart showing the opening / closing timing of the reflux control valve based on the concentration of NOx, and FIG. 6 is a schematic structural diagram showing a modification of the PCV system according to the second embodiment. The second embodiment differs from the first embodiment described above in that it includes a NOx concentration sensor, and other configurations and operations are generally the same. Therefore, in the second embodiment, the control based on the NOx concentration will be described in detail, and the description of other configurations will be omitted as appropriate. 3 and 6, the same reference numerals are given to the same components as the components according to the first embodiment shown in FIG. 1.

  In FIG. 3, the PCV system 1 according to the second embodiment includes a NOx concentration sensor 80, which is an example of the “first concentration detection unit” of the present invention, instead of the pressure sensor 70 in the first embodiment described above. 2 provided in the exhaust path 80. The NOx concentration sensor 80 detects the NOx concentration of the exhaust flowing inside the second exhaust passage portion 47. In the second embodiment, the reflux control valve 60 is controlled based on this NOx concentration.

  In FIG. 4, when the operation of the PCV system 1 for the internal combustion engine according to the second embodiment is started, first, the NOx concentration sensor 80 detects the NOx concentration in the second exhaust passage portion 47 (step S21). The detected NOx concentration is transmitted to the ECU 500, and the ECU 500 determines whether or not the detected NOx concentration sensor 80 exceeds a predetermined threshold value (step S22). The predetermined threshold is set based on, for example, the relationship between the NOx concentration in the exhaust and the failure occurrence rate of the internal combustion engine 100, which is obtained by simulation or the like.

  When it is determined that the NOx concentration exceeds the predetermined threshold (step S22: YES), the recirculation control valve 60 is closed, and control is performed so that the recirculated blowby gas is not released into the intake passage portion 31a (step S23). ). If it is determined that the NOx concentration does not exceed the predetermined threshold (step S22: NO), the recirculation control valve 60 is opened, and control is performed to release the recirculated blowby gas to the intake passage 31a ( Step S24). More specifically, for example, if the NOx concentration changes as shown in FIG. 5, the reflux control valve 60 is closed when the NOx concentration exceeds a predetermined threshold, and the NOx concentration decreases and falls below the predetermined threshold. And opened again. The reflux control valve 60 is controlled by repeatedly executing the above-described series of processing (step S21 to step S24).

  As described above, by controlling the recirculation control valve 60 based on the NOx concentration in the exhaust, it is possible to reduce that the blow-by gas having a high NOx concentration continues to be recirculated. Therefore, it is possible to prevent the NOx concentration in the blow-by gas accumulated in the internal combustion engine from becoming too high. Thereby, for example, it can be prevented that NOx reacts with oil and the oil is rapidly deteriorated. Further, it is possible to prevent the combustion in the internal combustion engine 100 from deteriorating when the blow-by gas is recirculated and recombusted.

  As shown in FIG. 6, the NOx concentration sensor 80 may be provided in the first exhaust passage portion 46 instead of the second exhaust passage portion 47. Even when the NOx concentration sensor 80 is provided as described above, the NOx concentration in the exhaust gas is similarly detected, and the recirculation control valve 60 can be suitably controlled. Moreover, the pressure sensor 70 provided in the first embodiment described above may also be provided. That is, the reflux control valve 60 may be controlled based on the NOx concentration and pressure.

  As described above, according to the PCV system 1 according to the second embodiment, it is possible to recirculate the blow-by gas while avoiding the adverse effects that occur when the NOx concentration in the blow-by gas increases.

<Third Embodiment>
Next, a PCV system according to the third embodiment will be described with reference to FIGS. FIG. 7 is a schematic structural diagram schematically showing the configuration of the PCV system according to the third embodiment. FIG. 8 is a schematic structural diagram showing a modification of the PCV system according to the third embodiment. It is. Note that the third embodiment is different from the second embodiment described above in the point where the concentration is measured by the NOx concentration sensor, and the other configurations and operations are generally the same. Therefore, in the second embodiment, portions different from those of the second embodiment will be described in detail, and description of overlapping portions will be omitted as appropriate. 7 and 8, the same reference numerals are given to the same components as the components according to the second embodiment shown in FIGS. 3 and 6.

  In FIG. 7, the PCV system 1 according to the third embodiment replaces the NOx concentration sensor 80 in the second embodiment described above with a NOx concentration sensor 90 that is an example of the “second concentration detection unit” of the present invention. The crankcase 5 is provided. The NOx concentration sensor 90 detects the NOx concentration of blow-by gas that flows inside the crankcase 5. In the third embodiment, the reflux control valve 60 is controlled based on this NOx concentration.

  The control of the reflux control valve 60 is performed in the same manner as in the second embodiment described above (see FIG. 4). That is, the reflux control valve 60 is closed when it is determined that the NOx concentration exceeds the predetermined threshold, and the reflux control valve 60 is opened when it is determined that the NOx concentration does not exceed the predetermined threshold. Note that the predetermined threshold is set based on, for example, the relationship between the NOx concentration in the crankcase 5 and the failure occurrence rate of the internal combustion engine 100 obtained by simulation or the like.

  By controlling the recirculation control valve 60 based on the NOx concentration in the crankcase 5, it is possible to reduce that the blow-by gas having a high NOx concentration continues to be recirculated. Therefore, it is possible to prevent the NOx concentration in the blow-by gas accumulated in the internal combustion engine from becoming too high. Thereby, for example, it can be prevented that NOx reacts with oil and the oil is rapidly deteriorated. Further, it is possible to prevent the combustion in the internal combustion engine 100 from deteriorating when the blow-by gas is recirculated and recombusted.

  As shown in FIG. 8, the NOx concentration sensor 90 may be provided at a position close to the oil separator 6 in the crankcase 5 (that is, near the gas outlet in the crankcase 5). For example, in the arrangement position as shown in FIG. 7, blow-by gas circulates in a pulse shape by the vertical movement of the piston 4. For this reason, it may be difficult to accurately measure the NOx concentration by the NOx concentration sensor 90. On the other hand, at the arrangement position as shown in FIG. 8, there is little influence by the vertical movement of the piston 4, and the NOx concentration can be measured more accurately. Therefore, the reflux control valve 60 can be controlled more suitably.

  In addition to the NOx concentration sensor 90, the NOx concentration sensor 80 provided in the second embodiment described above may also be provided. If comprised in this way, since the recirculation | reflux control valve 60 can be controlled by comprehensively considering the detection results of the NOx concentration sensors 80 and 90, for example, it becomes possible to recirculate blowby gas more suitably.

  As described above, according to the PCV system 1 according to the third embodiment, as in the second embodiment described above, the blow-by gas is avoided while avoiding the adverse effects that occur when the NOx concentration in the blow-by gas increases. Can be refluxed.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. The system is also included in the technical scope of the present invention.

1 is a schematic structural diagram schematically showing a configuration of a PCV system according to a first embodiment. It is a flowchart (the 1) which shows the flow of the flow control of blow-by gas by a recirculation | reflux control valve. It is the schematic structure figure which showed the structure of the PCV system which concerns on 2nd Embodiment typically. It is a flowchart (the 2) which shows the flow of the flow control of blow-by gas by a recirculation | reflux control valve. It is a timing chart which shows the opening-and-closing timing of the recirculation | reflux control valve based on the density | concentration of NOx. It is a schematic structure figure showing the modification of the PCV system concerning a 2nd embodiment. It is the schematic structure figure which showed the structure of the PCV system which concerns on 3rd Embodiment typically. It is a schematic structure figure showing the modification of the PCV system concerning a 3rd embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... PCV system, 2 ... Air cleaner, 3 ... Supercharger, 4 ... Piston, 5 ... Crankcase, 10 ... Reed valve, 23 ... Cylinder, 25 ... Cover part, 31 ... 1st intake passage part, 42 ... 2nd Intake passage section, 43 ... first flow path section, 44 ... second flow path section, 50 ... pump, 60 ... reflux control valve, 70 ... pressure sensor, 80, 90 ... NOx concentration sensor, 100 ... internal combustion engine, 500 ... ECU

Claims (10)

An internal combustion engine having (i) a cylinder, (ii) a crankcase, (iii) a supercharger that takes air into the cylinder, and (iv) a piston that reciprocates in the cylinder in response to fuel combustion in the cylinder When,
A cover portion for sealing a space in the case inside the crankcase;
It is provided in the cover part and opens in response to a rise in pressure in the case internal space generated by the piston moving in the cylinder toward the case internal space, and blow-by gas is discharged from the case internal space. Discharging means for discharging,
A first flow path portion for recirculating the discharged blow-by gas downstream of the supercharger on the intake side of the internal combustion engine;
When the downstream pressure is not a negative pressure, a second flow path portion that recirculates the discharged blow-by gas upstream of the supercharger on the intake side of the internal combustion engine;
A PCV system for an internal combustion engine, comprising: a pump that is provided in the middle or at the end of the second flow path portion and that promotes recirculation of the discharged blow-by gas.   2. The PCV for an internal combustion engine according to claim 1, further comprising a recirculation control valve that is provided on the downstream side of the pump in the second flow path portion and controls a flow rate of the recirculated blowby gas. system.   The PCV of the internal combustion engine according to claim 2, wherein the recirculation control valve is opened and closed so as not to recirculate the discharged blow-by gas when intake by the supercharger is performed. system. Pressure detecting means for detecting the downstream pressure;
Determination means for determining whether or not intake by the supercharger is performed based on the detected pressure; and
The PCV system for an internal combustion engine according to claim 2 or 3, wherein the reflux control valve controls the flow rate based on the determination. A first concentration detecting means for detecting the concentration of NOx on the exhaust side of the internal combustion engine;
The PCV of the internal combustion engine according to any one of claims 2 to 4, wherein the recirculation control valve controls the flow rate based on a NOx concentration detected by the first concentration detecting means. system. A second concentration detecting means for detecting the NOx concentration in the crankcase;
The PCV system for an internal combustion engine according to any one of claims 2 to 5, wherein the reflux control valve controls the flow rate based on a NOx concentration detected by the second concentration detection means. . A third flow path portion constituting a flow path of gas flowing from the upstream side of the reflux position by the second flow path portion upstream of the supercharger to the cylinder head of the cylinder;
A first one-way valve provided in the third flow path portion;
A fourth flow path portion constituting a flow path of gas flowing from the downstream of the supercharger to the cylinder head;
And a regulating valve that is provided downstream of the supercharger and between the fourth flow path portions and adjusts the amount of gas flowing to the cylinder head by the fourth flow path portions. Item 7. The PCV system for an internal combustion engine according to any one of Items 1 to 6.   8. The PCV system for an internal combustion engine according to claim 1, further comprising a second one-way valve provided downstream of the pump in the second flow path portion.   9. The oil separator according to claim 1, further comprising an oil separator provided between the discharge means and the first and second flow path portions, and separating the blow-by gas and oil from each other. An internal combustion engine PCV system according to claim 1.   10. The internal combustion engine PCV according to claim 1, further comprising an air cleaner provided upstream of a recirculation position by the second flow path portion upstream of the supercharger. 11. system.

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