JP2006250080A - Internal combustion engine with blowby gas treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine with a blowby gas treatment device, capable of more efficiently performing forced ventilation of blowby gas inside the engine. <P>SOLUTION: The internal combustion engine 10 is provided with a secondary air supply device comprising an air pump 31 sucking air and pressurizing and discharging it and a secondary air supply path 33 supplying the pressurized and discharged air to an engine exhaust system. The internal combustion engine 10 is further provided with a flow rate control valve 32 functioning as a change-over valve which selectively switches a fresh air supply path 45 for supplying the pressurized and discharged air by the air pump 31 to inside of a head cover 13, a breather path 42 for communicating inside of the head cover 13 with an engine intake system, and a path connected with the air pump 31 between the secondary air supply path 33 and the fresh air supply path 45. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine equipped with a blow-by gas processing device that recirculates blow-by gas inside an engine during intake.

  As a device applied to internal combustion engines such as in-vehicle, ventilation of the combustion gas (blow-by gas) leaking into the crankcase from the gap between the cylinder and piston is performed, and the ventilated blow-by gas is recirculated into the intake air. Blow-by gas processing devices for processing are known. In such an internal combustion engine with a blow-by gas processing device, the blow-by gas recirculated into the intake air is recombusted in the combustion chamber, so that the amount of hydrocarbon (HC) discharged into the atmosphere can be reduced. Further, the deterioration of oil due to blow-by gas can be suppressed by ventilation inside the engine.

  FIG. 9 shows a configuration of a general blow-by gas processing apparatus. As shown in the figure, the blow-by gas processing apparatus generally includes a fresh air introduction passage 101, a breather passage 102, and a PCV (Positive Crankcase Ventilation) valve 103.

  The fresh air introduction path 101 communicates the inside of the head cover 104 and the engine such as the crankcase 105 (in the apparatus shown in the figure, the inside of the head cover 104) and the upstream side of the throttle valve 108 that is the atmospheric pressure side of the intake passage 107. It has become a passage. Such a fresh air introduction path 101 is used to introduce air outside the engine (outside air) into the engine. The breather passage 102 is a passage that communicates the inside of the engine (crankcase 105 in the apparatus shown in the figure) with the downstream side of the throttle valve 108 that is the negative pressure side of the intake passage 107, and blow-by gas inside the engine is taken into the intake passage. Used for delivery into 107. On the other hand, the PCV valve 103 is disposed in the breather passage 102 and is a differential pressure operating valve whose opening degree is changed according to the differential pressure between the crankcase 105 side and the intake passage 107 side.

  In such a blow-by gas processing apparatus, the blow-by gas inside the engine is generated by the differential pressure between the inside of the engine that has become atmospheric pressure due to the introduction of outside air through the fresh air introduction passage 101 and the intake negative pressure downstream of the throttle valve 108 in the intake passage 107. Is sucked and recirculated during inhalation. Further, the opening degree of the PCV valve 103 is changed in accordance with such a differential pressure, whereby the flow rate of blow-by gas recirculated into the intake air through the breather passage 102 is adjusted autonomously.

  In a device that performs natural ventilation of blow-by gas using only the differential pressure between the intake negative pressure and the atmospheric pressure, the differential pressure between the intake negative pressure and the atmospheric pressure is too large, for example, in an engine high load operation region. In situations where this is not the case, ventilation inside the engine may not be sufficiently performed.

Therefore, as seen in Patent Document 1, conventionally, a blow-by gas inside the engine is forcibly ventilated by using a negative pressure pump for a brake master back provided in a brake device of a vehicle on which the internal combustion engine is mounted. A blow-by gas processing apparatus has been proposed. In this type of blow-by gas processing apparatus, as shown in FIG. 10, a negative pressure pump 112 for the brake master back 111 is disposed in the breather passage 102 of the blow-by gas processing apparatus. The negative pressure pump 112 sucks air in the brake master back 111 and at the same time sucks air containing blow-by gas in the crankcase 105 and discharges them together to the downstream side of the throttle valve 108 in the intake passage 107. . Thereby, forced ventilation of the blow-by gas inside the engine is possible without depending on the differential pressure between the intake negative pressure and the atmospheric pressure.
JP 2001-164918 A

  If the air pumps of other devices mounted in this way are also used for forced ventilation of blow-by gas inside the engine, the effect of engine operating conditions on ventilation performance is reduced while suppressing an increase in the number of parts. It is possible to some extent.

  However, in the above conventional blow-by gas processing apparatus, when the brake is used frequently, the air suction by the negative pressure pump 112 is exclusively used to form the negative pressure in the brake master back 111. There is a risk that forced ventilation cannot be performed sufficiently. In other words, the conventional blow-by gas processing apparatus cannot avoid the blow-by gas ventilation performance being greatly influenced by the use condition of the brake, and there is still room for improvement.

  The present invention has been made in view of such a situation, and the problem to be solved is to provide an internal combustion engine with a blow-by gas processing device capable of performing forced ventilation of blow-by gas inside the engine more efficiently. There is to do.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 is a secondary air supply comprising an air pump that sucks and pressurizes and discharges air outside the engine, and a secondary air supply passage that supplies the air discharged by the air pump to the engine exhaust system. In an internal combustion engine with a blow-by gas processing device, which is applied to an internal combustion engine equipped with a device and processes the blow-by gas inside the engine by recirculating it into the intake air, the fresh air for supplying the pressurized and discharged air of the air pump into the engine A switching valve for selectively switching a passage connected to the air pump between a supply passage, a breather passage communicating the inside of the engine and the engine intake system, and the secondary air supply passage and the fresh air supply passage The gist is to provide.

  According to a third aspect of the present invention, there is provided an air pump that sucks and pressurizes and discharges air outside the engine, and a secondary air supply passage that supplies the pressurized and discharged air of the air pump to the exhaust catalyst upstream side of the engine exhaust system. In an internal combustion engine with a blow-by gas processing device, which is applied to an internal combustion engine having a secondary air supply device having a recirculation function and recirculates the blow-by gas inside the engine into the intake air, the pressurized and discharged air of the air pump is the engine Air that is pressurized and discharged by the air pump between the fresh air supply path that is supplied to the interior, the breather passage that communicates the interior of the engine with the engine intake system, and the secondary air supply path and the fresh air supply path. And a flow rate control valve that makes the flow rate ratio variable.

  In the configuration according to claim 1, in response to switching of the connection by the switching valve, the pressurized and discharged air of the air pump is supplied to the secondary air supply path connected to the engine exhaust system and fresh air connected to the inside of the engine. It is selectively supplied to one of the supply paths. According to the third aspect of the present invention, the flow rate ratio of the pressurized and discharged air of the air pump is made variable between the secondary air supply path and the fresh air supply path by the flow rate control valve. That is, in each of the above-described configurations, the air pump is used for both the secondary air supply to the engine exhaust system and the forced ventilation inside the engine, and the air discharged and pressurized by the air pump is used both in time or It will be shared quantitatively.

  The secondary air supply device is one of the devices adopted in an internal combustion engine such as an in-vehicle vehicle, and is an air pump that sucks air and pressurizes and discharges the air, and a secondary that supplies air discharged and pressurized by the air pump to the engine exhaust system An air supply path is provided. Many secondary air supply apparatuses are provided with a switching valve for switching supply / stop of secondary air and a flow rate control valve for adjusting the supply amount of secondary air.

  The supply of secondary air to the engine exhaust system is performed exclusively for the purpose of quickly raising the temperature of the exhaust purification catalyst device at the time of engine cold start. That is, by supplying oxygen-containing air to the engine exhaust system, unburned fuel in the exhaust is oxidized, and the temperature of the catalyst device is promoted by the heat generated thereby. Therefore, the secondary air supply to the engine exhaust system is only required for a certain period (usually about 1 minute) after the engine is started. There is almost no opportunity to be used for supply, and the air discharged by the air pump can be used exclusively for forced ventilation inside the engine.

  Therefore, according to each structure of Claim 1 and Claim 3, forced ventilation of the blow-by gas inside an engine can be performed more efficiently. Incidentally, as described above, an internal combustion engine provided with a secondary air supply device is originally provided with an air pump for supplying secondary air, and is often provided with a switching valve and a flow control valve. Therefore, it is possible to implement each of the above configurations with almost no increase in the number of parts.

  In addition, as described in claim 2, the connection of the air pump to the secondary air supply path is performed at the time of engine cold start, and the connection of the air pump to the fresh air supply path is performed after the warm-up is completed. By operating the switching valve, it is possible to suitably perform early temperature rise of the catalyst device and ventilation inside the engine. In addition, normally, an air pump for a secondary air supply device that is rarely used except during cold start can be effectively utilized even after warm-up is completed.

  Further, as described in claim 4, the air pumped and discharged by the air pump is supplied to the secondary air supply path at the time of engine cold start, and is supplied to the fresh air supply path after the warm-up is completed. Similarly, by operating the described flow control valve, it is possible to suitably perform early temperature rise of the catalyst device and ventilation inside the engine. Also in this case, the air pump for the secondary air supply device that is rarely used except during the cold start can be effectively utilized even after the warm-up is completed.

  Further, as described in claim 5, if a new air introduction path for introducing air outside the engine into the engine without using an air pump is further provided, all of the air in the air pump is secondary air to the engine exhaust system. Even when used for supply, natural ventilation inside the engine using the differential pressure between atmospheric pressure and intake negative pressure can be continued.

  By the way, in an internal combustion engine that performs forced ventilation inside the engine using the above-described conventional negative pressure pump for brake master back, in an extremely cold environment such as in winter, the cryogenic temperature is reduced due to the suction of blow-by gas from the inside of the engine. A large amount of outside air is introduced into the engine. For this reason, the internal temperature of the engine is lowered, and there is a possibility of causing problems such as a decrease in the viscosity or deterioration of the oil. Further, in such an extremely cold environment, there is a possibility that the fresh air introduction path may be frozen and blocked by the cryogenic outside air.

  In that respect, the invention according to claim 6 is an internal combustion engine with a blow-by gas processing device that recirculates and processes blow-by gas inside the engine during intake, and includes an air pump that pressurizes and sends air outside the engine into the engine. I am doing so. In such a configuration, during forced ventilation, the air whose temperature has increased due to adiabatic compression accompanying the pressurizing and discharging operation of the air pump is sent into the engine, so that the above-described problems can be avoided appropriately.

  Even in such a case, as described in claim 7, if the air pump is also used for supplying secondary air to the engine exhaust system, the increase in the number of components can be suppressed.

Hereinafter, an embodiment of an internal combustion engine with a blow-by gas processing device of the present invention will be described in detail with reference to FIGS.
FIG. 1 shows the overall structure of such an internal combustion engine 10 with a blow-by gas processing device of this embodiment. As shown in the figure, the internal combustion engine 10 is roughly configured to include an engine body including a cylinder head 11, a cylinder block 12, and the like, and an intake passage 20 and an exhaust passage 21 connected thereto. The internal combustion engine 10 has a secondary air supply device that supplies air (secondary air) to the engine exhaust system and a blow-by gas inside the engine that is recirculated into the intake air in order to quickly raise the temperature of the exhaust purification catalyst device. A blow-by gas processing apparatus is provided for processing. In the internal combustion engine 10 of the present embodiment, the air pump 31 of the secondary air supply device is also used for forced ventilation of blow-by gas inside the engine in the blow-by gas processing device.

  A head cover 13 is mounted on the upper part of the cylinder head 11 constituting the engine body, and an oil pan 14 for storing engine lubricating oil is mounted on the lower part of the cylinder block 12. The cylinder block 12 is formed with a cylinder 15 in which a piston 16 is disposed so as to be able to reciprocate. The cylinder 15 is surrounded by the inner periphery of the cylinder 15, the top surface of the piston 16, and the lower surface of the cylinder head 11. Is formed. A crankcase 18 is formed below the cylinder block 12 and is covered with the oil pan 14 below.

  An intake passage 20 and an exhaust passage 21 are connected to the combustion chamber 17 of the engine body via an intake valve 22 and an exhaust valve 23, respectively. A throttle valve 24 for adjusting the flow rate of air supplied to the combustion chamber 17 through the intake passage 20 is disposed upstream of the intake passage 20. Further, an exhaust purification catalyst device 25 is disposed downstream of the exhaust passage 21.

  Various controls such as intake air amount control and fuel injection amount control related to the operation of the internal combustion engine 10 are performed by an electronic control unit (ECU: Electronic Control Unit) 19 for engine control. The electronic control device 19 receives detection signals from various sensors that detect engine operating conditions. For example, a rotation speed sensor that detects the engine rotation speed, an accelerator sensor that detects the accelerator operation amount, an air flow meter that detects the flow rate of air in the intake passage 20, and detects the oxygen concentration of the exhaust gas, and thus in the combustion chamber 17 A detection signal of an air-fuel ratio sensor for detecting the air-fuel ratio of the air-fuel mixture to be burned is input to the electronic control unit 19. The electronic control device 19 also receives detection signals from an intake air temperature sensor that detects the temperature of air in the intake passage 20 and a water temperature sensor that detects the temperature of engine cooling water.

Next, the configuration of the secondary air supply device and blow-by gas processing device applied to the internal combustion engine 10 will be described with reference to the same drawing.
The secondary air supply device includes a fresh air intake passage 30, an air pump 31, a flow control valve (ACV: Air Control Valve) 32, and a secondary air supply passage 33. The most upstream portion of the fresh air intake passage 30 is opened to the atmosphere via an air filter 34 for purifying the intake air. The fresh air intake passage 30 is provided with an air pump 31 that sucks outside air through the air filter 34 and discharges it to the downstream side of the fresh air intake passage 30. The downstream end of the fresh air intake passage 30 is connected to a flow control valve 32. A secondary air supply passage 33 is further connected to the flow control valve 32, and the downstream end of the secondary air supply passage 33 is opened upstream of the catalyst device 25 in the exhaust passage 21.

  The air pump 31 is controlled to be switched between operation and stop by the electronic control unit 19. In the internal combustion engine 10 of the present embodiment, an electrically driven air pump 31 that operates in response to external power feeding is employed.

On the other hand, the blow-by gas processing apparatus includes a blow-by gas passage 40, a fresh air introduction passage 41, a breather passage 42, and a PCV valve 43.
The blow-by gas passage 40 is formed in the cylinder head 11 and the cylinder block 12 so as to communicate the crankcase 18 and the inside of the head cover 13. The blow-by gas passage 40 is provided to lead the combustion gas leaked from the combustion chamber 17 into the crankcase 18 through the gap between the sliding surfaces of the cylinder 15 and the piston 16, that is, blow-by gas, into the head cover 13. It has been. A baffle plate 44 for separating blowby gas and oil mist is disposed inside the head cover 13.

  The fresh air introduction path 41 communicates the upstream side of the throttle valve 24 in the intake passage 20 with the inside of the head cover 13, and is provided to introduce outside air into the head cover 13. The breather passage 42 is provided to communicate the downstream side of the throttle valve 24 of the intake passage 20 with the inside of the head cover 13 and send blow-by gas inside the head cover 13 into the intake air flowing through the intake passage 20. Yes.

  A PCV valve 43 is disposed in the breather passage 42. The PCV valve 43 is configured as a differential pressure operating valve that operates according to the differential pressure between the inside of the head cover 13 on the upstream side and the downstream side of the throttle valve 24 of the intake passage 20 on the downstream side. By such a PCV valve 43, the flow rate of blow-by gas recirculated into the intake air through the breather passage 42 is autonomously adjusted according to the differential pressure.

  Further, in the blow-by gas processing apparatus for the internal combustion engine 10 of the present embodiment, a fresh air supply passage 45 is provided in addition to the fresh air introduction passage 41 and the breather passage 42. An upstream end of the fresh air supply path 45 is connected to the flow rate control valve 32, and a downstream end thereof is opened inside the head cover 13. Incidentally, the position of the opening of the fresh air supply path 45 inside the head cover 13 is desirably provided in the vicinity of a portion where the blow-by gas tends to stagnate inside the head cover 13 or a portion where a large amount of oil mist and blow-by gas exists. Moreover, you may make it open the fresh air supply path 45 in the several location inside the head cover 13 as needed.

  Thus, in the internal combustion engine 10 of the present embodiment, the flow control valve 32 has a three-way valve structure in which the three passages of the fresh air intake passage 30, the secondary air supply passage 33, and the fresh air supply passage 45 are connected. ing. In the following description, in this flow control valve 32, the port to which the fresh air supply path 45 is connected is the first port, the port to which the secondary air supply path 33 is connected is the second port, and the fresh air intake path 30 is connected. The port to be used is described as a third port. The flow control valve 32 is an electromagnetically driven valve that adjusts the opening degree of the first port and the second port with respect to the third port through duty control of the amount of power supplied to the built-in solenoid. The duty control of the power supply amount of the flow rate control valve 32 is performed by the electronic control unit 19.

  FIG. 2 shows the relationship between the control duty ratio of the power supply amount of the flow control valve 32 and the opening degrees of the first port and the second port with respect to the third port. As shown in the figure, in the flow rate control valve 32, only one of the first port and the second port is selectively opened with respect to the third port according to the control duty ratio. Yes. That is, the flow control valve 32 selectively selects a passage connected to the air pump 31 between the fresh air supply passage 45 connected to the first port and the secondary air supply passage 33 connected to the second port. Functions as a switching valve for switching. Further, in the flow rate control valve 32, the opening degree of the first port / second port is continuously changed according to the control duty ratio, and is sent from the air pump 31 to the fresh air supply path 45 or the secondary air supply path 33. The air flow rate can be finely controlled.

  In the internal combustion engine 10 of the present embodiment configured as described above, the electronic control unit 19 supplies secondary air to the engine exhaust system and forced ventilation inside the engine through the control of the air pump 31 and the flow rate control valve 32. Such air supply control is performed. Details of the air supply control in this embodiment will be described below with reference to FIGS.

  FIG. 3 shows a state when the secondary air supply to the engine exhaust system is performed. When the secondary air is supplied, the electronic control unit 19 controls the flow rate so that the second port and the third port communicate with each other and the secondary air supply path 33 is connected to the fresh air intake path 30 where the air pump 31 is disposed. The valve 32 is controlled.

  At this time, the pressure-discharged air of the air pump 31 is sent into the exhaust passage 21 through the secondary air supply passage 33. As a result, the unburned fuel in the exhaust is oxidized, and the temperature of the catalyst device 25 is increased by the heat generated therewith. At this time, if the differential pressure between the atmospheric pressure and the intake negative pressure is sufficient, air flows into the head cover 13 from the upstream side of the throttle valve 24 in the intake passage 20 through the fresh air introduction passage 41, Blow-by gas is sent from the inside of the head cover 13 to the downstream side of the throttle valve 24 in the intake passage 20 through the breather passage 42. That is, even when the secondary air is supplied to the exhaust system, it is possible to perform natural ventilation inside the head cover 13 according to the differential pressure between the atmospheric pressure and the negative intake pressure.

  On the other hand, FIG. 4 shows a state in which forced ventilation inside the head cover 13 is performed. In forced ventilation, the electronic control unit 19 connects the first port and the third port so that the fresh air supply passage 45 is connected to the fresh air intake passage 30 where the air pump 31 is disposed. Control.

  At this time, the pressure-discharged air of the air pump 31 is sent into the head cover 13 through the fresh air supply path 45. Thus, forced ventilation is performed inside the head cover 13, and blow-by gas inside the head cover 13 is sent to the intake valve 20 downstream of the throttle valve 24 through the breather passage 42. The blow-by gas recirculated during the intake air is sent to the combustion chamber 17 together with the intake air.

  If the pressure in the head cover 13 becomes higher than the atmospheric pressure due to the air supply from the air pump 31 at this time, the blow-by gas may flow back through the fresh air introduction path 41 depending on the configuration of the internal combustion engine 10. In such a case, it is preferable to provide a check valve, an orifice, or the like for restricting the backflow of blow-by gas toward the intake passage 20 in the fresh air introduction passage 41.

  In the present embodiment, the flow rate control valve 32 is operated to supply the pressurized air discharged from the air pump 31 to the secondary air supply path 33 as shown in FIG. The After the warm-up is completed and the air-fuel ratio feedback control is started, the flow control valve 32 supplies the air supplied by the air pump 31 to the fresh air supply passage 45 as shown in FIG. Operated to do. That is, in the air supply control, the electronic control device 19 performs connection of the air pump 31 to the secondary air supply path 33 at the time of engine cold start, and connection of the air pump 31 to the fresh air supply path 45 is completed after warm-up is completed. The operation control of the flow control valve 32 is performed so as to be performed.

In FIG. 5, an example of the control aspect of the air supply control in this embodiment is shown.
In this example, the internal combustion engine 10 is started at time T0 shown in FIG. Then, at the time T1 immediately after that, the electronic control device 19 starts the operation of the air pump 31 and controls the flow control valve 32 so as to open the second port connected to the secondary air supply path 33. Thereby, the supply of secondary air to the engine exhaust system for raising the temperature of the catalyst device 25 is started.

  With the start of such secondary air supply, the catalyst bed temperature is then raised relatively quickly. The electronic control device 19 estimates the warm-up degree (catalyst temperature rise) of the catalyst device 25 based on the elapsed time since the engine start, the engine coolant temperature, etc. Continue until the temperature rises. The electronic control device 19 also controls the flow rate control valve 32 so as to adjust the amount of secondary air supplied to the engine exhaust system in accordance with the warming-up degree of the catalyst device 25. Specifically, the electronic control unit 19 controls the flow rate control valve 32 so as to gradually reduce the supply amount of secondary air every time the catalyst temperature rise approaches a desired temperature.

  When the temperature of the catalyst device 25 is sufficiently raised at time T2, the electronic control device 19 temporarily stops the operation of the air pump 31, closes the second port of the flow control valve 32, and connects to the engine exhaust system. Stop the secondary air supply.

  When the warm-up is completed and the air-fuel ratio feedback control is started at time T3 thereafter, the electronic control unit 19 starts the operation of the air pump 31 again, and this time, the electronic control unit 19 is now connected to the fresh air supply path 45. The flow control valve 32 is controlled to open one port. Thereby, the pressure-discharged air of the air pump 31 is supplied into the head cover 13 and the forced ventilation inside thereof is started.

  If a large amount of blow-by gas is introduced into the intake air through such forced ventilation, the air-fuel ratio may be disturbed. In that respect, here, forced ventilation is started after the start of the air-fuel ratio feedback control, and such disturbance of the air-fuel ratio is corrected quickly through the air-fuel ratio feedback control, so that the exhaust performance of the internal combustion engine 10 is hardly affected. It is like that.

  During such forced ventilation inside the head cover 13, the electronic control device 19 controls the opening degree of the first port of the flow control valve 32 in accordance with the engine operation status detected by the various sensors. Specifically, the opening degree control at this time depends on the negative pressure state in the intake passage 20 estimated based on the opening degree of the throttle valve 24 and the engine rotational speed, the engine rotational speed, the engine load, the engine temperature state, and the like. The blow-by gas inside the head cover 13 is ventilated without excess or deficiency in view of the estimated blow-by gas generation state. In addition, in consideration of the current intake air amount and air-fuel ratio, the same opening degree control is performed so that the disturbance of the air-fuel ratio and the deterioration of exhaust performance accompanying the introduction of blow-by gas accompanying forced ventilation remain within an allowable range. It is also done to adjust the amount of blow-by gas introduced into the. For example, the electronic control unit 19 increases the opening degree of the first port of the flow control valve 32 at the time of high load operation with a large amount of blow-by gas generated and a small differential pressure between the atmospheric pressure and the intake negative pressure. The air supply amount of the air pump 31 is increased. On the other hand, the electronic control unit 19 reduces the opening degree of the first port of the flow control valve 32 when the amount of blow-by gas generated is small or when the differential pressure between the atmospheric pressure and the intake negative pressure is sufficiently large. The air supply amount of the air pump 31 to 13 is reduced.

FIG. 6 shows a flowchart of the air supply control in this embodiment. The electronic control unit 19 periodically and repeatedly executes a series of processes shown in FIG.
When the processing of this flowchart is started, the electronic control unit 19 first determines in step S10 whether or not the engine is cold start.

  If the engine is cold start (S10: YES), the electronic control unit 19 proceeds to step S20 and activates the air pump 31 in step S20. Further, the electronic control unit 19 opens the second port of the flow rate control valve (ACV) 32 in the subsequent step S30, and temporarily ends the current process. At this time, the secondary air is supplied to the engine exhaust system by the air pump 31.

  On the other hand, if the engine is not cold start (S10: NO), the electronic control unit 19 advances the process to step S40, and determines whether the warm-up is completed in step S40. Strictly speaking, the electronic control unit 19 at this time determines whether or not air-fuel ratio feedback control started after the completion of warm-up is being executed.

  If it is determined that the warm-up is complete (S40: YES), the electronic control unit 19 advances the process to step S50, and activates the air pump 31 in step S50. Further, in the subsequent step S60, the electronic control unit 19 opens the first port of the flow control valve (ACV) 32 in order to perform forced ventilation inside the head cover 13 by the air pump 31, and temporarily ends the current process. At this time, forced ventilation inside the head cover 13 by the air pump 31 is performed.

  If it is determined that the engine is not cold-started (S10: NO) and that the engine is not warmed up (S40: NO), the electronic control unit 19 advances the process to step S70. In step S70, the air pump 31 Stop. Further, the electronic control unit 19 closes all the ports of the flow control valve 32 in the subsequent step S80, and temporarily ends the current process.

According to the internal combustion engine 10 with the blow-by gas processing device of the present embodiment described above, the following effects can be achieved.
(1) In this embodiment, the air pump 31 is also used for secondary air supply to the engine exhaust system and for forced ventilation inside the engine. Since the supply of secondary air to the engine exhaust system is performed only during a certain period (usually about 1 minute) after the engine is started, during the other periods, the air discharged by the air pump 31 is exclusively used. It can be used for forced ventilation inside the engine. Therefore, the forced ventilation of blow-by gas inside the engine can be performed more efficiently without being influenced by the vehicle driving situation.

(2) Normally, the air pump 31 for the secondary air supply device, which is rarely used except during cold start, can be effectively utilized even after the warm-up is completed.
(3) Since a general secondary air supply device is originally provided with an air pump and a flow rate control valve, it can be realized with almost no increase in the number of parts.

  (4) Since the air whose temperature has been raised by adiabatic compression in the air pump 31 is sent into the head cover 13, the temperature inside the engine and the fresh air introduction path accompanying the introduction of extremely low temperature outside air in a cold environment such as winter Problems, such as deterioration of the ventilation performance accompanying freezing 41, can be avoided suitably.

  Incidentally, it is desirable that the air sucked into the combustion chamber 17 has a low temperature in order to increase the charging efficiency of the air in the cylinder and improve the output performance of the internal combustion engine 10. For this reason, air is generally taken into the intake passage 20 directly from the outside of the vehicle body at a lower temperature than the inside of the engine room, which is a factor for promoting the above-described problems. In this respect, in the present embodiment, the air supply path (fresh air intake path 30 and fresh air supply path 45) for forced ventilation by the air pump 31 is completely independent of the intake path 20, and therefore such engine output performance is achieved. Therefore, the route can be set without being restricted. Therefore, the route can be set so as to take in air from a portion having a relatively high air temperature, such as the inside of the engine room, whereby the above problems can be reduced more effectively.

  (5) In the present embodiment, as a passage for introducing air outside the engine into the head cover 13, the fresh air supply path 45 that supplies the air pressurized and discharged from the air pump 31 into the head cover 13 and the air pump 31 are used. Instead, there are two passages including a fresh air introduction passage 41 for introducing air outside the engine into the head cover 13. Therefore, even when forced ventilation by the air pump 31 is not performed, such as when supplying secondary air to the engine exhaust system, natural ventilation inside the head cover 13 according to the differential pressure between the atmospheric pressure and the intake negative pressure should continue. Can do. In addition, since more outside air can be introduced from both passages, the ventilation capacity inside the engine can be improved.

  (6) In the present embodiment, the air amount of the air pump 31 supplied into the head cover 13 is controlled according to the engine operation status through the opening degree control of the flow control valve 32. Appropriate ventilation performance without excess or deficiency can be maintained.

  (7) The inside of the head cover 13 has a complicated shape, and a number of portions having a bottleneck shape or a labyrinth shape are formed, and the blow-by gas is likely to stay in such portions. Therefore, when ventilating, it is desirable to introduce the fresh air into such a site and eliminate the staying blow-by gas. However, when the introduction of fresh air for ventilation relies only on the differential pressure between the atmospheric pressure and the intake negative pressure, the discharge flow of air into the head cover 13 is not so high, and the above-mentioned bottle-shaped or labyrinth-like If the fresh air introduction path 41 is opened at the site, the flow of the introduced fresh air may be delayed, and sufficient ventilation may not be possible. Therefore, the position where the opening of the fresh air introduction path 41 in the head cover 13 can be formed is limited to some extent. In this regard, the fresh air introduction path 41 through which the air pumped by the air pump 31 is discharged has a high air discharge flow, so that fresh air can be obtained without stagnation in the bottleneck or labyrinth areas as described above. Since it can be introduced, the formation position of the opening of the fresh air supply path 45 inside the head cover 13 can be set relatively freely. That is, an opening of the fresh air supply passage 45 is formed in the vicinity of a portion where blow-by gas is likely to stagnate or a portion where a large amount of oil mist and blow-by gas is present, or the fresh air supply passage 45 may be branched depending on circumstances. It is possible to relatively easily open the fresh air supply passage 45 at a plurality of locations. Therefore, according to the present embodiment, it is possible to further improve the ventilation efficiency by improving the position of introducing fresh air into the engine.

In addition, the said embodiment can also be changed and implemented as follows.
For example, as illustrated in FIG. 7, the downstream end of the fresh air supply path 45 ′ may be opened inside the crankcase 18. Further, the fresh air introduction passage 41 and the breather passage 42 may be connected to the crankcase 18. Even in such a case, forced ventilation of the blow-by gas inside the engine can be performed according to the air supply from the air pump 31, and the same effects as the above embodiment can be achieved.

  In the above embodiment, the flow control valve 32 is configured so that the air supply from the air pump 31 is selectively switched to only one of the fresh air supply passages 45 and 45 ′ and the secondary air supply passage 33. However, the configuration may be changed so that air can be supplied to both of them simultaneously. For example, FIG. 8 shows the relationship between the control duty ratio of the power supply amount and the opening degrees of the first port and the second port with respect to the third port in an example of the flow control valve configured as described above. In this example, when the control duty ratio is set within the range α shown in the figure, air from the air pump 31 is supplied to the engine exhaust system and the engine. Further, in this range α, the flow rate ratio of the pressurized and discharged air of the air pump 31 is variable between the secondary air supply path 33 and the fresh air supply path 45 in accordance with the value of the control duty ratio. It has become. If such a flow control valve is employed, the air that is pressurized and discharged by the air pump 31 can be quantitatively shared between the secondary air supply application to the exhaust system and the forced ventilation application inside the engine. Also in this case, since the engine operating condition that mainly requires air supply is different between the two applications, both of them can be efficiently performed with a single air pump 31 having a relatively small pumping capacity.

  In the above embodiment, the opening degree control of the flow rate control valve 32 is performed through duty control of the power supply amount, but the opening degree control of the flow rate control valve 32 may be performed in other modes.

  In the above embodiment, the air supply destination of the air pump 31 is switched so that secondary air is supplied to the engine exhaust system at the cold start and forced ventilation is performed inside the engine after the warm-up is completed. However, the air supply control mode according to the engine operating condition is not limited to this, and may be changed as appropriate.

  The air discharge amount of the air pump 31 can be adjusted, and the control of the air supply amount to the engine exhaust system and the engine is performed by the discharge amount control of the air pump 31 or the opening amount control of the flow control valve 32. You may make it carry out by using together.

  In the above embodiment, the PCV valve 43 is a differential pressure actuated valve, but it may be changed to a valve capable of opening control such as an electromagnetic control valve. In this case, the opening degree of the PCV valve 43 is appropriately controlled according to the inflow state of fresh air from the air pump 31 through the fresh air supply passage 45 and the intake negative pressure state in the intake passage 20, so that blow-by can be performed more effectively. Gas ventilation can be performed.

  -If there is no need to finely control the amount of air supplied to the engine exhaust system or the engine, the air pump 31 is alternatively connected to either the secondary air supply path 33 or the fresh air supply path 45. A simple switching valve that only does this may be used instead of the flow control valve 32. Even when such a switching valve is employed, if the air discharge amount of the air pump 31 is controlled, it is possible to precisely control the air supply amount to the engine exhaust system or the engine.

  In the above embodiment, the air supply control to the engine exhaust system and the inside of the engine is performed through the electronic control of the opening degree of the flow control valve 32. However, this is performed regardless of the electronic control. You can also. For example, a temperature-sensitive flow control valve that operates autonomously in response to the coolant temperature, intake air temperature, etc., or a pressure-sensitive flow that operates autonomously in response to the differential pressure between atmospheric pressure and intake negative pressure, etc. It is also possible to adopt a control valve or the like instead of the flow rate control valve 32 to perform air supply control similar to or equivalent to the above embodiment.

  If the ventilation performance inside the engine can be sufficiently secured only by forced ventilation according to the air supply from the air pump 31, the fresh air introduction path 41 may be omitted. Also in this case, effects other than the above (6) can be achieved.

The drive system of the air pump 31 may be changed to a system other than the electric drive system, for example, a mechanical drive system that operates using the rotation of the engine output shaft or a hydraulic drive system that operates using hydraulic pressure.
-An air pump may be provided exclusively for forced ventilation inside the engine without being used as a secondary air supply to the engine exhaust system. Even in such a case, if the air pump is configured so that air outside the engine is pressurized and sent into the engine, the air whose temperature has increased due to adiabatic compression accompanying the pressurizing and discharging operation of the air pump is forced into the engine during forced ventilation. It will be sent. For this reason, it is possible to suitably avoid problems such as a low internal temperature associated with the introduction of extremely low temperature outside air in a cold environment such as winter and a deterioration in ventilation performance associated with freezing of the fresh air introduction passage 41. In such a case, the present invention can also be applied to an internal combustion engine that does not include a secondary air supply device.

The schematic diagram which shows the whole structure about one Embodiment of the internal combustion engine with a blowby gas processing apparatus which concerns on this invention. The graph which shows the relationship between the control duty ratio of the flow control valve employ | adopted as the same embodiment, and the opening degree of each port. The schematic diagram which shows an example of the operation | movement aspect at the time of the engine cold start about the same embodiment. The schematic diagram which shows an example of the operation | movement aspect at the time of the engine high load driving | operation about the embodiment. (A)-(c) The time chart which shows an example of the control aspect of the said air supply control. The flowchart which shows the process sequence of the air supply control applied to the embodiment. The schematic diagram which shows the whole structure about other embodiment of the internal combustion engine with a blowby gas processing apparatus which concerns on this invention. The graph which shows the relationship between the control duty ratio of the flow control valve and the opening degree of each port about further another embodiment of the internal combustion engine with a blow-by gas processing device concerning the present invention. The schematic diagram which shows the structure of a general blowby gas processing apparatus. The schematic diagram which shows the structure of the conventional blowby gas processing apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Cylinder head, 12 ... Cylinder block, 13 ... Head cover, 14 ... Oil pan, 15 ... Cylinder, 16 ... Piston, 17 ... Combustion chamber, 18 ... Crankcase, 19 ... Electronic control device for engine control , 20 ... intake passage, 21 ... exhaust passage, 22 ... intake valve, 23 ... exhaust valve, 24 ... throttle valve, 25 ... catalyst device, 30 ... fresh air inflow passage, 31 ... air pump, 32 ... flow control valve (switching valve) , 33 ... Secondary air supply passage, 34 ... Air filter, 40 ... Blow-by gas passage, 41 ... Fresh air introduction passage, 42 ... Breather passage, 43 ... PCV valve, 44 ... Baffle plate, 45, 45 '... Fresh air Supply path.

Claims (7)

Applied to an internal combustion engine including a secondary air supply device having an air pump that sucks and pressurizes and discharges air outside the engine and a secondary air supply path that supplies the air discharged and discharged from the air pump to the engine exhaust system. In the internal combustion engine with a blow-by gas processing device for processing the blow-by gas inside the engine by recirculating it into the intake air,
A fresh air supply path for supplying the air discharged under pressure from the air pump into the engine;
A breather passage communicating the inside of the engine and the engine intake system;
A switching valve for selectively switching a passage connected to the air pump between the secondary air supply passage and the fresh air supply passage;
An internal combustion engine with a blow-by gas processing device.   2. The switching valve is operated so that the air pump is connected to the secondary air supply path at the time of engine cold start, and the air pump is connected to the fresh air supply path after warm-up is completed. An internal combustion engine with a blow-by gas processing device as described in 1. An internal combustion engine comprising a secondary air supply device having an air pump that sucks and pressurizes and discharges air outside the engine, and a secondary air supply passage that supplies the pressure-discharged air of the air pump to the exhaust catalyst upstream side of the engine exhaust system In an internal combustion engine with a blow-by gas processing device that is applied to an engine and recirculates the blow-by gas inside the engine into the intake air for processing.
A fresh air supply path for supplying the air discharged under pressure from the air pump into the engine;
A breather passage communicating the inside of the engine and the engine intake system;
A flow rate control valve that makes the flow rate ratio of the pressurized and discharged air of the air pump variable between the secondary air supply path and the fresh air supply path;
An internal combustion engine with a blow-by gas processing device.   The flow control valve is operated to supply the air discharged under pressure from the air pump to the secondary air supply path at the time of engine cold start and to supply the fresh air supply path after the warm-up is completed. An internal combustion engine with a blow-by gas processing device as described in 1. The internal combustion engine with a blow-by gas processing device according to any one of claims 1 to 4,
An internal combustion engine with a blow-by gas processing device, further comprising a fresh air introduction path for introducing air outside the engine into the engine without passing through the air pump.   An internal combustion engine with a blow-by gas processing device, wherein an internal combustion engine with a blow-by gas processing device that recirculates and processes blow-by gas inside the engine into intake air is provided with an air pump that pressurizes and sends air outside the engine into the engine.   The internal combustion engine with a blow-by gas processing device according to claim 6, wherein the air pump is also used for supplying secondary air to an engine exhaust system.

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