JP5533153B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a cooling device having a water pump for engine cooling water whose discharge amount can be changed without depending on the rotation state of the engine output shaft, and blow-by gas for adjusting the amount of blow-by gas recirculated to the intake passage. The present invention relates to a control device for an internal combustion engine including a reflux device.

  As a water pump that circulates cooling water in the engine cooling system, an engine drive type that has been widely used conventionally, that is, the discharge amount is uniquely determined based on the rotation speed of the engine output shaft driven by the engine output shaft. In recent years, a cooling device for an internal combustion engine that employs an electric water pump capable of independently changing the discharge amount instead of the determined water pump has been put into practical use. In such a cooling device that employs an electric water pump, unlike the engine-driven water pump, the discharge amount of the water pump, in other words, the circulation amount of the cooling water in the engine cooling system is output to the engine. Adjustment can be made without depending on the rotational state of the shaft. For this reason, when it is not necessary to cool the internal combustion engine, for example, when the engine is cold started, the start of the water pump is delayed until the temperature of the cooling water rises to some extent, and the circulation of the cooling water is stopped. Thus, warm-up of the internal combustion engine can be promoted.

  By the way, during engine operation, a part of the combustion gas generated with combustion of the air-fuel mixture leaks into the crankcase as blow-by gas from the gap between the cylinder bore and the piston. Since this blow-by gas has strong oxidizability, when it comes into contact with the oil in the crankcase (exactly an oil pan), it causes early deterioration due to oxidation of the oil. Therefore, in general, an internal combustion engine is provided with a PCV passage that connects the intake passage and the crankcase or the inside of the cylinder head cover that is in communication therewith, and the blow-by gas staying in the crankcase is returned to the intake passage through the PCV passage. This is then burned and processed.

  Moreover, since such blow-by gas contains many combustible components, the influence on the engine combustion state cannot be ignored depending on the engine operation state at that time. For this reason, a PCV valve is usually provided in the PCV passage, and the opening degree of the PCV valve is adjusted based on the engine operating state so that the recirculation of the blow-by gas does not have an excessive influence on the engine combustion state. I have to. For example, in the internal combustion engine described in Patent Document 1, when the engine is warmed up, the combustion state of which is difficult to stabilize, the PCV valve is fully closed until a predetermined period elapses from the time of engine warm-up, and the blow-by gas to the combustion chamber is The reflux is stopped.

JP 2009-216051 A

  By the way, when the circulation of the cooling water is stopped when the engine is cold as described above, the amount of blow-by gas leaking to the crankcase tends to temporarily increase as compared with the case where this is performed. This is thought to be due to the following reasons.

  That is, when the air-fuel mixture burns in the engine combustion chamber, the cylinder bore and the piston both rise in temperature due to the combustion heat, and are thermally expanded accordingly. Here, the cylinder bore has a large amount of heat exchange with the cooling water compared to the piston (exactly the piston ring), and its cooling efficiency is high. Therefore, the amount of temperature increase when the cooling water is circulated and when it is stopped. The difference, in other words, the difference in the amount of thermal strain becomes large. That is, when the cooling water is stopped compared to when the cooling water is circulated, the amount of thermal strain of the cylinder bore with respect to the piston increases, and therefore a relatively large gap is generated between the two. Become. Along with this, the amount of blow-by gas leaking from the engine combustion chamber to the crankcase also temporarily increases.

  For this reason, as in the apparatus described in Patent Document 1, the PCV valve is fully closed during engine warm-up to stop the recirculation of blow-by gas, and in conjunction with this, the circulation of the cooling water is stopped as described above. If this is done, it is possible to suppress the deterioration of the combustion state of the engine due to the recirculation of blow-by gas, but a large amount of blow-by gas stays in the crankcase, leading to early deterioration of the oil and its This can lead to more serious problems such as the generation of oil sludge with degraded oil as the core. Here, the case where the circulation of the cooling water is stopped when the engine is cold has been described as an example. However, the circulation amount of the cooling water is limited to an extremely small amount so as to promote early warm-up. Even in some cases, similar problems can occur to varying degrees.

  The present invention has been invented in view of the above problems, and provides a control device for an internal combustion engine that contributes to making it difficult for the crankcase to accumulate a large amount of blowby gas during warm-up of the internal combustion engine. It is an object.

[1] One embodiment of the control device for the internal combustion engine has the following matters. The internal combustion engine has an engine output shaft, an engine cooling system, a crankcase, an intake passage, a cooling device, and a blow-by gas recirculation device, and the cooling device has an electric water pump and a water temperature sensor, The water pump has a structure capable of circulating cooling water in the engine cooling system and changing the discharge amount of the cooling water, and the water temperature sensor outputs a signal that changes according to the temperature of the cooling water. The blow-by gas recirculation device has a communication path and a flow rate control valve, the communication path connects the crankcase and the intake path to each other, and the flow rate control valve has the communication path adjust the flow rate of the blow-by gas in the controller, the signal of the temperature of the cooling water be within the scope of the above judgment temperature the temperature sensor during the warm-up of the internal combustion engine The water pump is operated, and when the signal of the water temperature sensor indicates that the temperature of the cooling water during warm-up of the internal combustion engine belongs to a range below the determination temperature, Based on the fact that the operation of the water pump is stopped and the water pump is operated, a control method for controlling the opening degree of the flow control valve according to the output of the sensor indicating the operation state of the internal combustion engine is selected. The flow control is performed more than when the flow control valve is opened and the opening degree of the flow control valve is controlled by the control method based on stopping the operation of the water pump. Select a control method to increase the valve opening.
[2] One embodiment of the control device for the internal combustion engine has the following matters. The internal combustion engine includes an engine output shaft, an engine cooling system, a crankcase, an intake passage, a cooling device, and a blow-by gas recirculation device. The cooling device includes a mechanical water pump, a clutch, and a water temperature sensor. The water pump is driven by the engine output shaft, circulates cooling water in the engine cooling system, and the clutch connects or disconnects the water pump and the engine output shaft from each other, and the water temperature sensor Outputs a signal that changes according to the temperature of the cooling water to the control device, the blow-by gas recirculation device includes a communication passage and a flow rate control valve, and the communication passage includes the crankcase and the intake passage. were connected to each other, said flow control valve, said adjusting the flow rate of the blow-by gas in the communication passage, wherein the control device, put into the warming-up of the internal combustion engine When the water temperature sensor signal suggests that the temperature of the cooling water belongs to a range equal to or higher than the determination temperature, the water pump and the engine output shaft are connected to each other by controlling the clutch, When the water temperature sensor signal indicates that the temperature of the cooling water during warm-up of the internal combustion engine belongs to a range lower than the determination temperature, the clutch is controlled to control the water pump. By disconnecting the engine output shaft from each other, the operation of the water pump is stopped, and the flow rate is determined according to the output of the sensor indicating the operation state of the internal combustion engine based on the operation of the water pump. Based on the fact that the control method for controlling the opening degree of the control valve is selected and the operation of the water pump is stopped, the flow control valve To form a valve state, and selects a control method of increasing the opening of the flow control valve than when controlling the opening of the flow control valve by the control method.
[3] One embodiment of the control device for the internal combustion engine has the following matters. Based on the fact that the operation of the water pump is stopped, the control device indicates the opening of the flow control valve when the flow control valve is in the open state by the signal of the water temperature sensor. The flow control valve is changed based on the temperature of the cooling water at the time of starting the internal combustion engine, and the opening degree of the flow control valve is increased as the temperature of the cooling water at the time of starting the internal combustion engine decreases.
[4] One embodiment of the control device for the internal combustion engine has the following matters. Based on the temperature of the cooling water suggested by the signal of the water temperature sensor when the control device is causing the flow rate control valve to open based on stopping the operation of the water pump. The opening degree of the flow control valve is changed, and the opening degree of the flow control valve is increased as the temperature of the cooling water increases.
[5] An embodiment of the control device for the internal combustion engine has the following matters. The control device is based on a length of a period during which the operation of the water pump is stopped when the flow control valve is in an open state based on the operation of the water pump being stopped. The opening of the flow control valve is changed, and the opening of the flow control valve is increased as the period becomes longer.
[6] An embodiment of the control device for the internal combustion engine has the following matters. The control device causes the flow rate control valve to form a fully open state based on the fact that the operation of the water pump is stopped.
[7] One embodiment of the control device for the internal combustion engine has the following matters. The control device starts the operation of the water pump when the signal of the water temperature sensor indicates that the temperature of the cooling water during the warm-up of the internal combustion engine has increased and has reached the determination temperature, From the start of operation of the water pump until the extremely low flow rate period elapses, the water pump is made to discharge extremely low flow rate cooling water, and after the extremely low flow rate period has elapsed, the water pump is Cooling water having a flow rate higher than the extremely low flow rate is discharged, and the flow control is performed after the extremely low flow rate period has elapsed from the start of the operation of the water pump until the extremely low flow rate period has elapsed. Increase the opening of the valve.

The control device [1] or [2] has the following effects.
When the operation of the water pump is stopped while the internal combustion engine is warming up, the flow control valve forms an open state. For this reason, the blow-by gas in the crankcase is returned to the intake passage. For this reason, a situation in which a large amount of blow-by gas accumulates in the crankcase during the warm-up of the internal combustion engine is less likely to occur.
When the cooling water does not circulate through the engine cooling system, the difference in the amount of thermal strain between the piston and the cylinder bore becomes larger than when the cooling water circulates through the engine cooling system. For this reason, the gap between the piston and the cylinder bore becomes large. For this reason, the amount of blow-by gas that leaks into the crankcase from the gap between the piston and the cylinder bore tends to increase. For this reason, a large amount of blow-by gas tends to stay in the crankcase.
On the other hand, the flow rate control valve forms an open state when the operation of the water pump is stopped while the internal combustion engine is warming up. For this reason, the blow-by gas in the crankcase is returned to the intake passage. For this reason, even if a large amount of blowby gas leaks into the crankcase from the gap between the piston and the cylinder bore, a situation in which a large amount of blowby gas accumulates in the crankcase during warming up of the internal combustion engine is less likely to occur.

The control device [3] has the following effects.
When the cooling water does not circulate through the engine cooling system during the warm-up of the internal combustion engine, the difference in the amount of thermal strain between the piston and the cylinder bore increases as the temperature of the cooling water at the start of the internal combustion engine decreases. For this reason, the gap between the piston and the cylinder bore becomes large. For this reason, the amount of blow-by gas that leaks into the crankcase from the gap between the piston and the cylinder bore tends to increase.
On the other hand, when the water pump is stopped while the internal combustion engine is warming up, the degree of opening of the flow control valve increases as the temperature of the cooling water at the start of the internal combustion engine decreases. For this reason, a situation in which a large amount of blow-by gas accumulates in the crankcase during warm-up of the internal combustion engine is less likely to occur.

The control device [4] has the following effects.
When the cooling water does not circulate through the engine cooling system while the internal combustion engine is warming up, the difference in the amount of thermal strain between the piston and the cylinder bore increases as the temperature of the cooling water at that time increases. For this reason, the gap between the piston and the cylinder bore becomes large. For this reason, the amount of blow-by gas that leaks into the crankcase from the gap between the piston and the cylinder bore tends to increase.
On the other hand, when the water pump is stopped while the internal combustion engine is warming up, the degree of opening of the flow control valve increases as the temperature of the cooling water at that time increases. For this reason, a situation in which a large amount of blow-by gas accumulates in the crankcase during warm-up of the internal combustion engine is less likely to occur.

The control device [5] has the following effects.
When the cooling water does not circulate through the engine cooling system during warm-up of the internal combustion engine, the difference in the amount of thermal strain between the piston and the cylinder bore increases as the period during which the cooling water does not circulate through the engine cooling system becomes longer. For this reason, the gap between the piston and the cylinder bore becomes large. For this reason, the amount of blow-by gas that leaks into the crankcase from the gap between the piston and the cylinder bore tends to increase.
On the other hand, when the water pump is stopped during the warm-up of the internal combustion engine, the opening degree of the flow control valve increases as the period during which the operation of the water pump is stopped is longer. For this reason, a situation in which a large amount of blow-by gas accumulates in the crankcase during warm-up of the internal combustion engine is less likely to occur.

The control device [6] has the following effects.
Since the flow rate control valve is fully opened, the amount of blow-by gas recirculated from the crankcase to the intake passage increases. For this reason, a situation in which a large amount of blow-by gas accumulates in the crankcase during warm-up of the internal combustion engine is less likely to occur.

The control device [7] has the following effects.
When the cooling water is not circulating through the engine cooling system and the cooling water is circulating through the engine cooling system, when a large amount of cooling water circulates through the engine cooling system at one time, it exists around the combustion chamber. The high-temperature cooling water that flows into the low-temperature part of the engine cooling system flows into the periphery of the combustion chamber. For this reason, there is a risk of thermal shock. On the other hand, the water pump discharges cooling water with an extremely low flow rate until the extremely low flow rate period elapses. For this reason, it becomes difficult to produce a thermal shock.
The clearance between the piston and the cylinder bore during the extremely low flow rate period is larger than when the cooling water circulates through the engine cooling system after the extremely low flow rate period has elapsed. For this reason, the amount of blow-by gas that leaks into the crankcase from the gap between the piston and the cylinder bore tends to increase.
On the other hand, the opening degree of the flow control valve during the extremely low flow period is larger than the opening degree of the flow control valve after the extremely low flow period has elapsed. For this reason, it is difficult for a situation in which a large amount of blow-by gas accumulates in the crankcase during an extremely low flow rate period.
As described above, according to the present control device, the occurrence of thermal shock caused by the cooling water circulating in the engine cooling system is less likely to occur, and in order to obtain this effect, the water pump has an extremely low flow rate of cooling water. Due to the discharge of gas, a situation where a large amount of blow-by gas accumulates in the crankcase is less likely to occur.

1 is a schematic configuration diagram showing an internal combustion engine and a control device thereof in a first embodiment of the present invention. The schematic block diagram of the cooling device of the internal combustion engine concerning the embodiment. The flowchart which shows the process sequence about the water pump drive control concerning the embodiment. (A) Sectional drawing of the piston to which the piston ring was attached concerning the embodiment, (b) The top view which shows the joint periphery periphery of a piston ring. The graph which shows transition of the internal diameter of the cylinder bore concerning the same embodiment, and the outer diameter of a piston. The flowchart which shows the process sequence about the opening degree control of the PCV valve concerning the embodiment. (A) a graph showing the relationship between the engine speed and engine load and the basic opening of the PCV valve according to the embodiment; (b) the relationship between the cooling water temperature and the correction coefficient for setting the opening of the PCV valve. Graph showing. The timing chart which shows an example of transition of (a) cooling water temperature concerning the same embodiment, (b) the drive mode of a water pump, and (c) PCV opening degree. The timing chart which shows an example of transition of (a) cooling water temperature concerning 2nd Embodiment, (b) the drive mode of a water pump, and (c) PCV opening degree. The timing chart which shows an example of transition of (a) cooling water temperature concerning 3rd Embodiment, (b) the drive mode of a water pump, and (c) PCV opening degree. The timing chart which shows an example of transition of (a) cooling water temperature concerning 4th Embodiment, (b) the drive mode of a water pump, and (c) PCV opening degree. The timing chart which shows an example of transition of (a) cooling water temperature concerning other embodiment, (b) the drive mode of a water pump, and (c) PCV opening degree. (A) The graph which shows the relationship between the cooling water temperature at the time of engine starting, and PCV opening degree concerning other embodiment, (b) The graph which shows the relationship between the cooling water temperature at the time of engine starting, and a correction coefficient.

(First embodiment)
Hereinafter, an internal combustion engine control apparatus according to the present invention will be described with reference to FIGS.
As shown in FIG. 1, a plurality of cylinder bores 15 (one of which is shown in FIG. 1) are formed in the cylinder block 11 of the internal combustion engine 10, and a piston 17 can reciprocate inside these cylinder bores 15. Is housed in. A cylinder head cover 18 and a cylinder head 12 are assembled to the upper part of the cylinder block 11, and an oil pan 14 for storing oil is assembled to a crankcase 13 corresponding to the lower portion thereof. The cylinder block 11 and the cylinder head 12 are each formed with a water jacket 52 through which cooling water circulates, and the temperature of the cooling water is near the cooling water outlet of the water jacket 52 formed in the cylinder head 12. A water temperature sensor 92 that detects (cooling water temperature θ) is attached.

  An intake passage 20 and an exhaust passage 21 are connected to the combustion chamber 16 of the internal combustion engine 10 defined by the top surface of the piston 17 and the lower surface of the cylinder head 12. The cylinder head 12 is provided with an intake valve 22 for connecting / blocking the combustion chamber 16 and the intake passage 20 and an exhaust valve 23 for connecting / blocking the combustion chamber 16 and the exhaust passage 21 so as to reciprocate. Yes.

  The intake passage 20 is provided with a throttle valve 24 that adjusts the amount of intake air introduced into the combustion chamber 16 based on the opening thereof. The intake air introduced into the combustion chamber 16 through the intake passage 20 as the intake valve 22 is opened is mixed with fuel in the combustion chamber 16 and burned. Exhaust gas generated by this combustion is discharged into the exhaust passage 21 when the exhaust valve 23 is opened.

  During operation of the internal combustion engine 10, a part of the combustion gas generated in the combustion chamber 16 with the combustion of the air-fuel mixture leaks into the crankcase 13 as blow-by gas from the gap between the cylinder bore 15 and the piston 17. And since this blow-by gas has strong oxidizability, when it comes into contact with the oil in the crankcase 13, the oil oxidizes and causes its early deterioration, or the generation of oil sludge with the deteriorated oil as the core is generated. As described above, the problem of being encouraged is caused.

  In view of this, the internal combustion engine 10 is provided with a blow-by gas recirculation device 40 that recirculates the blow-by gas staying in the crankcase 13 to the intake passage 20, introduces it again into the combustion chamber 16 together with the intake air, and burns it with the air-fuel mixture. ing.

  As shown in FIG. 1, the blow-by gas recirculation device 40 is attached to the recirculation passage 42, which connects the inside of the cylinder head cover 18 and the downstream portion of the throttle valve 24 in the intake passage 20, and the recirculation passage. PCV valve 41 that adjusts the amount of blow-by gas that is recirculated from 42 to intake passage 20, and fresh air introduction passage 43 that connects cylinder head cover 18 to a portion of intake passage 20 upstream of throttle valve 24. . The crankcase 13 and the inside of the cylinder head cover 18 are communicated with each other by a plurality of communication passages 11 a formed in the cylinder block 11. Therefore, the blow-by gas staying in the crankcase 13 can flow into the cylinder head cover 18 through these communication paths 11a.

  The blow-by gas in the crankcase 13 is sucked out by the action of negative pressure generated in the intake passage 20 and introduced into the intake passage 20 through the communication passage 11a, the inside of the cylinder head cover 18, and the return passage 42. Along with this, fresh air is introduced from the fresh air introduction passage 43 into the cylinder head cover 18 and the crankcase 13. Thereby, the inside of the cylinder head cover 18 and the crankcase 13 is ventilated, while the blow-by gas introduced into the intake passage 20 is introduced into the combustion chamber 16 and burned. The PCV valve 41 is a valve whose opening degree is controlled by an actuator such as a motor.

  Next, the cooling device 50 for the internal combustion engine 10 will be described with reference to FIG. The cooling device 50 includes a water temperature sensor 92 and an electric water pump 56 that uses a motor as a driving source, a rotation speed sensor 93 that detects a rotation speed of the water pump 56 (rotation speed of the motor), a radiator 51, and a thermostat. 57, and a cooling water passage 53 including a bypass passage 55 that bypasses the water jacket 52 and the radiator 51. In the cooling device 50, the cooling water passage 53, the radiator 51, the thermostat 57, and the like constitute an engine cooling system. Further, a thermal device (not shown) such as a heater core or an EGR cooler is provided in the middle of the bypass passage 55, and a thermostat 57 is provided at the downstream end thereof. This thermostat 57 is a temperature-sensitive autonomous opening / closing valve in which the position of a valve provided therein changes in accordance with the cooling water temperature θ, and in the cooling water passage 53, the downstream portion of the radiator 51 and the upstream of the water pump 56. The flow rate of the cooling water flowing through the radiator 51 is adjusted by changing the communication state with the side portion through the opening degree. That is, when the cooling water temperature θ is low, the cooling water is prevented from flowing from the radiator 51 to the water jacket 52, and the cooling water is allowed to flow from the bypass passage 55 to the water jacket 52. On the other hand, when the cooling water temperature θ increases, the cooling water is allowed to flow from the radiator 51 to the water jacket 52. As a result, the cooling water discharged from the water pump 56 to the water jacket 52 returns to the water pump 56 again via the radiator 51. In the radiator 51, heat exchange is performed between the cooling water and the outside air, and as a result, the cooling water temperature θ decreases.

  By the way, at the time of cold start, it is desirable to complete the warm-up of the internal combustion engine 10 early in order to reduce heat loss and improve fuel efficiency. Therefore, in the cooling device 50 of the present embodiment, the driving of the water pump 56 is stopped until the warm-up of the internal combustion engine 10 proceeds to some extent, and the circulation of the cooling water in the cooling water passage 53 is prohibited. Such drive control of the water pump 56 is executed by the control device 91. The control device 91 takes in the detection values of various sensors such as the water temperature sensor 92 and the rotation speed sensor 93 and drives the water pump 56 in a predetermined manner based on the drive signal generated from the detection values of these sensors. Execute various controls. In order to execute such control, the control device 91 includes a CPU, a memory, an A / D conversion circuit, and a drive circuit.

  Next, the drive control of the water pump 56 will be described in detail with reference to FIG. Note that the series of processing shown in FIG. 3 is repeatedly executed at predetermined intervals by the control device 91 after the engine is started.

  First, the control device 91 determines whether or not the temperature of the cooling water in the vicinity of the combustion chamber 16 (hereinafter, combustion chamber cooling water temperature θc) is high, that is, at the sliding portion of the piston 17 and the cylinder bore 15 that are the highest in the internal combustion engine 10. It is determined whether or not there is a possibility of thermal failure such as burn-in (step S110).

  Here, an example of a method for estimating the combustion chamber cooling water temperature θc will be described. The combustion chamber cooling water temperature θc is calculated based on the detected value of the water temperature sensor 92 detected at that time (hereinafter referred to as “detected cooling water temperature θ” in particular when distinguishing from the combustion chamber cooling water temperature θc and the like). That is, the combustion chamber cooling water temperature θc is always higher than the detected cooling water temperature θ. Further, when a high load operation is performed during engine warm-up, the amount of heat generated in the combustion chamber 16 increases, and accordingly, the combustion chamber cooling water temperature θc rises locally. The local increase in the combustion chamber cooling water temperature θc changes according to the amount of combustion heat generated in the combustion chamber 16 from the start of the engine to the present, and this amount of combustion heat is an integrated value of the fuel injection amount. It changes in correlation with (fuel injection amount integrated value Σq). Therefore, the combustion chamber cooling water temperature θc can be obtained by the function F using the detected cooling water temperature θ and the fuel injection amount integrated value Σq as parameters, as shown in the following equation (1). The function F is obtained in advance through experiments or the like and is stored in the memory of the control device 91 as a calculation map.

θc (i) ← {(n1-1) · θc (i-1) + n1 · F (θ, Σq)} / n1 (1)

In the above equation (1), “θc (i)” represents the combustion chamber cooling water temperature in the current control cycle, and “θc (i−1)” represents the combustion chamber cooling water temperature in the previous current control cycle. “N1” is a correction coefficient (gradual change coefficient), and is a coefficient for calculating this in consideration of a response delay of the combustion chamber cooling water temperature θc with respect to fluctuations in combustion heat. Incidentally, the correction coefficient n1 is set to a larger value as the response delay of the combustion chamber cooling water temperature θc is larger. The correction coefficient n1 is set in advance through experiments or the like such as considering the amount of heat transfer from the combustion chamber 16 to the surrounding cooling water, and is stored in the memory of the control device 91.

  When it is determined that the combustion chamber cooling water temperature θc is high, that is, there is a risk of seizure of the piston 17 and the cylinder bore 15 in the combustion chamber 16 or local boiling of the cooling water in the vicinity of the combustion chamber 16 (step S110: YES) ), The operation mode of the water pump 56 is set to the normal control mode (step S120), and a flag (operation mode determination flag FP) for determining the operation mode of the water pump 56 is set to “2” (step S125). In this case, the control device 91 determines the discharge amount of the water pump 56 based on the target amount (normal target amount) set according to the engine operating state such as the engine rotation speed, the engine load, the cooling water temperature θ, and so on. The target rotational speed is set, and the actual rotational speed detected by the rotational speed sensor 93 is controlled to be the target rotational speed. As a result, an amount of cooling water corresponding to the engine operating state is circulated, and the internal combustion engine 10 is maintained at a temperature suitable for realizing stable engine combustion.

  On the other hand, when it is determined that the previous combustion chamber cooling water temperature θc is low (step S110: NO), next, whether or not the internal combustion engine 10 is in a low temperature state, in other words, the internal combustion engine 10 does not need to be cooled by the cooling water. It is determined whether or not it is in a temperature state (step S130). Specifically, the control device 91 determines whether or not the coolant temperature θ is equal to or higher than a predetermined circulation stop temperature θx. When it is determined that the internal combustion engine 10 is in a low temperature state (step S130: YES), the control device 91 sets the operation mode of the water pump 56 to the stop mode (step S140), and sets the operation mode determination flag FP to “0”. (Step S145). In this case, the control device 91 stops driving the water pump 56 to promote warming up of the internal combustion engine 10. Therefore, the cooling water is not circulated in the engine cooling system.

  On the other hand, when it is determined that the internal combustion engine 10 is not in a low temperature state (step S130: NO), it is next determined whether or not the internal combustion engine 10 has been warmed up, in other words, the internal combustion engine 10 needs to be cooled with cooling water. It is determined whether or not it is in a temperature state (step S150). Specifically, the control device 91 determines whether or not the cooling water temperature θ is equal to or higher than a predetermined temperature θy. The predetermined temperature θy is a temperature that is higher than the predetermined circulation stop temperature θx and is set in advance so that it can be determined that the internal combustion engine 10 is in a completely warmed-up state.

  Here, when it is determined that the warm-up of the internal combustion engine 10 has not been completed (step S150: YES), the control device 91 sets the operation mode of the water pump 56 to the extremely low flow rate mode (step S160), and the operation mode determination flag. The FP is set to “1” (step S165). Specifically, the discharge amount of the water pump 56 is smaller than the normal target amount (for example, the target discharge amount of the water pump 56 when the cooling water temperature θ temporarily falls below the predetermined temperature θy after completion of complete warm-up). This is limited so that the circulation amount of the cooling water is extremely low.

  As described above, after the cooling water temperature θ reaches the predetermined circulation stop temperature θx, the discharge amount of the water pump 56 is limited so that the circulation amount of the cooling water becomes an extremely low flow rate until the cooling water temperature θ becomes equal to or higher than the predetermined temperature θy. The reason is as follows. That is, when the operation mode of the water pump 56 is the stop mode and the operation is stopped from the time when the operation is stopped, if a large amount of cooling water is circulated at a time, the water pump 56 exists around the combustion chamber 16. The high temperature cooling water whose temperature has risen flows into the low temperature portion of the cooling device 50. On the other hand, the cooling water in the low temperature part flows into the high temperature part around the combustion chamber 16. And when the temperature distribution state in an engine cooling system changes suddenly in this way, there is a possibility that a thermal shock (thermal shock) may occur in each part of the cooling device 50. Therefore, in order to avoid such a thermal shock, the controller 91 sets the operation mode to the extremely low flow rate mode before the operation mode of the water pump 56 is shifted from the stop mode to the normal control mode. Yes.

  On the other hand, when it is determined that the warm-up of the internal combustion engine 10 has been completed (step S150: NO), the controller 91 sets the water pump 56 to the normal control mode (step S170), and sets the operation mode determination flag FP to “2”. (Step S175).

  As shown in FIG. 4A, three ring grooves 17c are formed on the outer peripheral surface of the piston 17, and the ring groove 17c ensures the airtightness of the combustion chamber 16 and the inner periphery of the cylinder bore 15. Piston rings 17a are respectively attached for the purpose of forming an appropriate oil film on the surface. An expander 17b that presses the piston ring 17a against the inner peripheral surface of the cylinder bore 15 is disposed on the inner peripheral side of the piston ring 17a. Further, as shown in FIG. 4B, the piston ring 17a is formed with an abutment in order to easily perform the attaching operation to the ring groove 17c.

  As described above, since the piston ring 17 a is pressed against the inner peripheral surface of the cylinder bore 15 by the expander 17 b, the inner diameter of the cylinder bore 15 is relative to the outer diameter of the piston 17 due to the combustion heat of the combustion chamber 16. Even when the diameter of the piston ring 17a is increased, the piston ring 17a can maintain a state in which the piston bore 17a is in contact with the inner peripheral surface of the cylinder bore 15 following the increase in the inner diameter. In this case, the joint of the piston ring 17a is enlarged.

  By the way, when the operation mode of the water pump 56 is selected as the stop mode and the circulation of the cooling water in the cooling water passage 53 is stopped, the operation mode of the water pump 56 is compared with that in the normal control mode. The amount of blow-by gas that leaks to the crankcase 13 through the gap S (see FIG. 4B) between the cylinder bore 15 and the piston 17 located between the joints tends to increase temporarily.

  The reason why the amount of blow-by gas temporarily increases will be described. FIG. 5 shows changes in the inner diameter of the cylinder bore 15 and the outer diameter of the piston 17 during engine warm-up. In FIG. 5, the transition of the inner diameter of the cylinder bore 15 when the operation mode of the water pump 56 is set to the normal control mode is indicated by a broken line. Timing t0 indicates when the engine is started, and timing t1 indicates the time when the cooling water temperature θ reaches θz and the circulation of the cooling water is started.

  When the air-fuel mixture burns in the combustion chamber 16, the cylinder bore 15 and the piston 17 both rise in temperature due to the combustion heat, and are thermally expanded accordingly. Here, when the amount of heat exchange between the cylinder bore 15 and the cooling water is compared with the amount of heat exchange between the piston 17 and the cooling water, the amount of heat exchange between the cylinder bore 15 and the cooling water is larger. In the internal combustion engine 10, even in such a case, when the operation mode of the water pump 56 is the normal control mode so that the clearance CL between the cylinder bore 15 and the piston 17 is substantially constant, that is, during engine operation. The specifications of the cylinder bore 15 and the piston 17 are set in advance in accordance with the situation where the time occupies the most.

On the other hand, when the operation mode of the water pump 56 is in the stop mode, the flow of cooling water does not occur, so the amount of heat exchange between the cylinder bore 15 and the cooling water is reduced compared to when in the normal control mode. . On the other hand, since the amount of heat exchange between the piston 17 and the cooling water is small in the first place, there is almost no difference in the amount of heat exchange caused by the difference in the operation mode of the water pump 56 that occurs in the cylinder bore 15 ( In FIG. 5, it is assumed that the change is negligible). For this reason, the clearance CL (= CL2) between the cylinder bore 15 and the piston 17 when the operation mode of the water pump 56 is in the stop mode is larger than the clearance CL (= CL1) when the operation mode is in the normal control mode. Also grows. In addition, the size of the joint is also enlarged accordingly. As a result, a gap S (see FIG. 4b) between the cylinder bore 15 and the piston 17 located between the joints of the piston ring 17a is increased, and the blow-by gas leaking from the combustion chamber 16 to the crankcase 13 through the gap S. The amount of will also increase.

  Further, as the combustion time in the combustion chamber 16 becomes longer, in other words, as the time for which the cylinder bore 15 and the piston 17 receive the combustion heat becomes longer, the difference in the heat exchange amount due to the different operation modes as described above further increases. Therefore, the clearance CL between the cylinder bore 15 and the piston 17 and the clearance S serving as the above-described blow-by gas flow passage also increase. Along with this, the amount of blow-by gas leaking from the combustion chamber 16 to the crankcase 13 also gradually increases.

  Therefore, in the present embodiment, when the operation mode of the water pump 56 is in the stop mode, the amount of blow-by gas recirculated to the intake passage 20 is increased so that the blow-by gas in the crankcase 13 is discharged quickly. The opening degree VA of the PCV valve 41 (hereinafter referred to as “PCV opening degree VA”) is set larger than that in the control mode. Hereinafter, with reference to FIG. 6, the process sequence concerning the valve opening degree control of the PCV valve 41 in this embodiment is demonstrated.

  In the series of processes shown in FIG. 6, it is first determined whether or not the operation mode of the water pump 56 is the normal control mode, that is, whether or not the operation mode determination flag FP of the water pump 56 is “2”. (Step S210). If it is determined that the operation mode of the water pump 56 is not the normal control mode (step S210: NO), whether or not the operation mode of the water pump 56 is the stop mode, that is, the operation mode determination flag FP is set. It is determined whether or not it is “0” (step S240).

  Here, when it is determined that the operation mode of the water pump 56 is not the stop mode (step S240: NO), that is, when it is determined that the operation mode of the water pump 56 is in the extremely low flow rate mode, and in the previous step S210. When it is determined that the operation mode of the water pump 56 is the normal control mode (step S210: YES), the opening degree of the PCV valve 41 is set to an opening degree that matches the situation where the cooling water is circulated. This is calculated (step S220).

  In this process, first, the basic opening VABASE of the PCV valve 41 is calculated. As shown in FIG. 7A, the basic opening VABASE is set to a larger value as the engine speed is higher and as the engine load is larger. That is, as the engine rotational speed is higher and the engine load is larger, the amount of combustion gas generated in the combustion chamber 16 is increased and the amount of blow-by gas is increased accordingly. The opening VABASE is increased.

  Next, a correction coefficient K1 for correcting the basic opening VABASE of the PCV valve 41 is calculated. As shown in FIG. 7B, the correction coefficient K1 is set to a larger value as the cooling water temperature θ is higher. As described above, as the inner diameter of the cylinder bore 15 increases due to thermal expansion, the gap S tends to increase. Therefore, the amount of blow-by gas that leaks to the crankcase 13 through the gap S also tends to increase. Therefore, the correction coefficient K1 is set to a larger value as the cooling water temperature θ is higher. When the cooling water temperature θ is lower than the predetermined water temperature θz, the correction coefficient K1 is set to “0” on the assumption that the amount of blow-by gas leaking into the crankcase 13 is an amount that is almost negligible. After calculating the correction coefficient K1 in this way, the PCV opening VA is set based on the following equation (2).

VA ← VABASE · K1 (2)

On the other hand, when it is determined that the operation mode of the water pump 56 is the stop mode (step S240: YES), the PCV opening VA is set to the predetermined opening VA1 (step S250). The predetermined opening VA1 is set to be always larger than the PCV opening VA set when the operation mode is the normal control mode.

  FIG. 8 shows (a) the cooling water temperature θ, (b) the driving state of the water pump 56, and (c) the transition of the PCV opening VA when the above-described pump drive control and valve opening control are executed. . Further, in FIG. 8C, the transition of the PCV opening VA when the operation mode of the water pump 56 is set to the stop mode in the period of the timing t0 to t2 is indicated by a solid line in the normal control mode or the extremely low flow rate. The transition of the PCV opening VA when the mode is set is indicated by a broken line with a broken line.

  During the period from when the engine is started to when the cooling water temperature θ rises and reaches the circulation stop temperature θx, the operation mode of the water pump 56 is set to the stop mode (timing t0 to t2). At this time, the PCV opening VA is maintained at the predetermined opening VA1. Since the predetermined opening VA1 is larger than the opening during normal control (see FIG. 8C and the above equation (2)), a large amount of blow-by gas is recirculated from the crankcase 13 and the cylinder head cover 18 to the intake passage 20. The combustion chamber 16 can be combusted. When the cooling water temperature θ reaches the circulation stop temperature θx, the operation mode of the water pump 56 is set to the extremely low flow rate mode so that the cooling water is discharged and the circulation of the cooling water is started. (Timing t2). When the circulation of the cooling water is thus started, the PCV opening VA is set based on the above formula (1). Thereafter, when the coolant temperature θ further rises and reaches a predetermined temperature TY, the operation mode of the water pump 56 is set to the normal control mode (timing t3 to timing 3).

According to this embodiment described above, the following effects can be obtained.
(1) In this embodiment, since the water pump 56 is not operated during engine warm-up and the circulation of cooling water is stopped, the amount of blow-by gas leaking from the combustion chamber 16 to the crankcase 13 is temporarily reduced. When it increases, the PCV opening VA is made larger than the opening during normal control so that the amount of blow-by gas recirculated from the crankcase 13 to the intake passage 20 is increased. Therefore, even when the operation mode of the water pump 56 is set to the stop mode and a large amount of blowby gas temporarily leaks into the crankcase 13 while the internal combustion engine 10 is warming up, this remains in the crankcase 13. Can be avoided, and the early deterioration of oil and the generation of oil sludge resulting therefrom can be suppressed.

(Second Embodiment)
The second embodiment according to the present invention will be described focusing on the differences from the first embodiment with reference to FIG. 9 in addition to FIG. 6 and FIG. In addition, about the structure and process similar to 1st Embodiment, the detailed description is omitted by attaching | subjecting the same code | symbol and step number.

  As shown in the flowchart of FIG. 6, in the first embodiment, when it is determined that the operation mode of the water pump 56 is in the stop mode (step S240: YES), the PCV opening VA is set to a predetermined opening. Set to VA1.

In this embodiment, when it is determined that the operation mode of the water pump 56 is in the stop mode (step S240: YES), the PCV opening VA is set based on the following equation (3).

VA ← VABASE · K2 (3)

Here, “K2” on the right side of the above equation (3) is a predetermined correction coefficient determined in advance through a test or the like, and as the cooling water temperature θ increases as shown by the one-dot chain line in FIG. It is set large. Further, as shown in FIG. 7B, a magnitude relationship of (K2> K1) is established regardless of the cooling water temperature θ. Therefore, the PCV opening VA calculated based on the above equation (3) is always larger than the value calculated based on the above equation (2). Thus, when the stop mode is selected as the operation mode of the water pump 56, the PCV opening degree VA is always higher than that during normal control, that is, when the normal control mode or the extremely low flow rate mode is selected. The PCV opening degree VA is set to a larger value as the cooling water temperature θ is set higher.

  FIG. 9 shows (a) the cooling water temperature θ, (b) the driving state of the water pump 56, and (c) the transition of the PCV opening VA when the above-described valve opening control of the PCV valve 41 is executed. . In FIG. 9C, the transition of the PCV opening VA when the operation mode of the water pump 56 is set to the stop mode in the period of the timing t0 to t2 is indicated by a solid line in the normal control mode or the extremely low flow rate. The transition of the PCV opening VA when the mode is set is indicated by a broken line with a broken line.

  During the period from when the engine is started to when the cooling water temperature θ rises and reaches the circulation stop temperature θX, the operation mode of the water pump 56 is set to the stop mode (timing t0 to t2). At this time, the PCV opening VA is set to a value calculated by the above equation (3). Since the PCV opening VA at this time is larger than the opening during normal control (see FIG. 9C and the above equation (2)), a large amount of blow-by gas is sucked from the crankcase 13 or the cylinder head cover 18 or the like. It can be returned to the passage 20 and burned in the combustion chamber 16. In particular, as the coolant temperature θ increases, that is, as the clearance S existing at the joint of the piston ring 17a increases as described above and the amount of blow-by gas leaking from the combustion chamber 16 to the crankcase 13 increases, Since the degree VA is set to a large value, the recirculation amount of the blowby gas can be adjusted in accordance with the leakage amount of the blowby gas. When the cooling water temperature θ reaches the circulation stop temperature θx, the operation mode of the water pump 56 is set to the extremely low flow rate mode so that the cooling water is discharged and the circulation of the cooling water is started. (Timing t2). When the circulation of the cooling water is thus started, the PCV opening VA is set based on the above equation (1). Thereafter, when the cooling water temperature θ further rises and reaches a predetermined temperature θy, the operation mode of the water pump 56 is set to the normal control mode (timing t3−).

According to this embodiment described above, in addition to the function and effect described in (1) above, the following function and effect can be achieved.
(2) As described above, unlike the case where the cooling water is circulated, when the circulation of the cooling water is stopped, the gap between the cylinder bore 15 and the piston 17 increases, and the abutment also growing. Furthermore, since the difference between the amounts of thermal strain between the two increases as the cooling water temperature θ increases, the gap S serving as a flow passage for blow-by gas also increases (see FIG. 4B). In this regard, according to the present embodiment, when the operation mode of the water pump 56 is in the stop mode, the PCV opening VA is set to be larger as the cooling water temperature θ is higher, and more blow-by gas is recirculated to the intake passage 20. Therefore, the stay of blow-by gas in the crankcase 13 can be more appropriately suppressed.

(Third embodiment)
The third embodiment according to the present invention will be described focusing on the differences from the first embodiment with reference to FIG. 10 in addition to FIG. Note that the same configurations and processes as those in the first embodiment are denoted by the same reference numerals and step numbers, and detailed description thereof is omitted.

  In the first embodiment, when it is determined that the operation mode of the water pump 56 is in the extremely low flow rate mode (step S240: NO), the same calculation as that when it is determined that the operation mode of the water pump 56 is in the normal control mode. The PCV opening VA was set according to the procedure.

On the other hand, in this embodiment, when the operating mode of the water pump 56 is determined to be in the very low flow rate mode (step S240: NO), than when the operating mode of the water pump 56 is in the stop mode, PCV opening VA Is set to a small value.

  As shown in FIG. 5, after the cooling water temperature θ reaches the circulation stop temperature θx, circulation of the cooling water is started, so that the amount of heat exchange between the cylinder bore 15 and the cooling water increases. For this reason, the gap between the inner diameter of the cylinder bore 15 and the outer diameter of the piston 17 gradually decreases, and the joint of the piston ring 17a also decreases accordingly. Along with this, the passage area of the gap S serving as the flow passage for the blow-by gas described above also decreases. Therefore, during the period when the operation mode of the water pump 56 is set to the extremely low flow rate mode, the amount of blow-by gas leaking to the crankcase 13 is gradually reduced.

  Therefore, in the present embodiment, as shown in FIG. 10, after the cooling water temperature θ reaches a predetermined circulation stop temperature θx and the operation mode of the water pump 56 is changed from the stop mode to the extremely low flow mode, the cooling is performed. In the period from when the water temperature θ reaches the predetermined temperature θy until the operation mode shifts to the normal control mode (timing t2 to t3), the operation mode of the water pump 56 is set to the stop mode. It is made smaller than the opening degree.

According to this embodiment described above, in addition to the effects (1) and (2) described above, the following effects can be achieved.
(3) When the operation mode of the water pump 56 is in the extremely low flow rate mode, a gap is generated between the cylinder bore 15 and the piston 17, but unlike the case where the operation mode of the water pump 56 is in the stop mode, a small amount However, since the cooling water is circulated, the amount of blow-by gas leaking from the combustion chamber 16 to the crankcase 13 gradually decreases. In this embodiment, paying attention to this point, when the operation mode of the water pump 56 is in the extremely low flow rate mode, the PCV opening VA is made smaller than when the operation mode is the stop mode. Thereby, the recirculation amount can be set according to the amount of blow-by gas leaking from the combustion chamber 16 to the crankcase 13, and the stay in the crankcase 13 can be suitably suppressed.

(Fourth embodiment)
A fourth embodiment according to the present invention will be described with reference to FIG. 11 focusing on differences from the first embodiment. Note that the same reference numerals are assigned to the same components as those in the first embodiment, and detailed description thereof is omitted.

  In the first embodiment, when the operation mode of the water pump 56 is in the extremely low flow rate mode, the PCV opening VA is the same as when the operation mode of the water pump 56 is in the normal control mode. It is set based on the cooling water temperature θ.

  In this embodiment, as shown in FIG. 11, after the operation mode of the water pump 56 has shifted to the extremely low flow rate mode, the PCV opening degree VA when the operation mode of the water pump 56 is in the normal control mode is set. In order to converge, the PCV opening VA is calculated through a gradual change process using the following equation (4).

VA (i) ← {(n2-1) · VA (i-1) + n2 · VABASE · K1} / n2 (4)

In the above equation (4), “VA (i)” indicates the opening of the PCV valve 41 in the current control cycle, and “VA (i−1)” indicates the same opening in the previous current control cycle. . “N2” is a correction coefficient (gradual change coefficient), and the flow of the above-mentioned blow-by gas as the operation mode of the water pump 56 is changed from the stop mode to the normal control mode through the extremely low flow rate mode. This is a coefficient that is set so that the PCV opening VA changes in accordance with the decreasing speed when the gap S that becomes the road decreases. The correction coefficient n2 is set in advance through experiments or the like and stored in the memory of the control device 91.

  As shown in FIG. 11, according to the present embodiment, when the coolant temperature θ reaches a predetermined circulation stop temperature θx and the operation mode of the water pump 56 shifts to the extremely low flow rate mode (timing t2), the PCV opening VA Will converge to the PCV opening VA when the operation mode of the water pump 56 is in the normal control mode (timing t2).

According to this embodiment described above, the following effects can be obtained.
(4) PCV set immediately after the operation mode of the water pump 56 shifts to the extremely low flow rate mode, with respect to the PCV opening VA immediately before the operation mode of the water pump 56 shifts from the stop mode to the extremely low flow rate mode. If the opening degree VA is greatly deviated, the flow rate of the blow-by gas recirculated to the intake passage 20 through the PCV valve 41 changes rapidly, which is not preferable in maintaining a stable combustion state. In this regard, according to the embodiment, after the operation mode of the water pump 56 shifts from the stop mode to the extremely low flow rate mode, the flow rate of the blow-by gas returned to the intake passage 20 through the PCV valve 41 gradually changes. It becomes possible to suppress a sudden change in the reflux amount of the blowby gas.

  In addition, the embodiment of the present invention is not limited to the embodiment exemplified in each of the above-described embodiments, and can be implemented by changing this as shown below, for example. The following modifications are not applied only to the above embodiments, and different modifications can be combined with each other.

  In each of the above embodiments, when the operation mode of the water pump 56 is the normal control mode or the extremely low flow rate mode, when calculating the PCV opening VA, first, the basic opening VABASE is calculated, and this is calculated as the cooling water temperature. The same opening degree VA is calculated by performing correction based on the correction coefficient K1 obtained by θ. The opening degree VA of the PCV valve 41 is used as parameters for the engine speed, the engine load, and the cooling water temperature θ. You may make it obtain | require from the map for calculation.

  As shown in FIG. 12, during the period in which the operation mode of the water pump 56 is in the stop mode, the PCV opening VA is set to increase according to the cooling water temperature θ as described in the second embodiment (timing t0 To t2), during the period in which the operation mode of the water pump 56 is in the extremely low flow rate mode, the PCV opening VA is set to an opening larger than that in the normal control mode as described in the third embodiment (timing t2 to t3). You may do it. According to this embodiment, the effect according to said (1)-(3) can be show | played.

  As shown in FIG. 13A, the value VA1 of the PCV opening VA shown in the first embodiment is made smaller as the detected value (cooling water temperature θ) of the water temperature sensor 92 at the time of starting the engine is higher. It may be. Further, a correction coefficient α for further correcting the correction coefficient K1 may be set, and as shown in FIG. 13B, the correction coefficient α may be made smaller as the cooling water temperature θ at the time of starting the engine is higher. . In FIG. 13B, the correction coefficient α when the operation mode of the water pump 56 is in the stop mode is indicated by a solid line, and the correction coefficient α when the operation mode of the water pump 56 is in the extremely low flow rate mode. Indicated by a dashed line. According to the present embodiment, the lower the coolant temperature θ at the time of starting the engine, the greater the difference in the amount of thermal strain between the cylinder bore 15 and the piston 17 at the time of engine warm-up, and therefore, between the cylinder bore 15 and the piston 17. The generated gap also increases, and the amount of blow-by gas that leaks from the combustion chamber 16 to the crankcase 13 through the gap S described above also increases. According to this modification, the amount of blow-by gas that leaks from the combustion chamber 16 to the crankcase 13 during the period when the operation mode of the water pump 56 is in the stop mode is estimated based on the cooling water temperature θ at the time of starting the engine. The PCV opening VA is increased as the amount of blow-by gas is increased. As a result, the stay of blow-by gas in the crankcase 13 can be more appropriately suppressed.

  In each of the above embodiments, the combustion chamber cooling water temperature θc is estimated based on the cooling water temperature θ detected by the water temperature sensor 92 and the fuel injection amount integrated value Σq from the time of starting the engine. It is not limited to. For example, it is calculated based on a function having as a parameter an appropriate combination of the coolant temperature θ at the time of engine start, the coolant temperature detected at that time, the fuel injection amount integrated value Σq, the engine rotational speed, the intake air temperature, the outside air temperature, etc. You can also

  In the above embodiment, the operation mode of the water pump 56 is changed based on the combustion chamber cooling water temperature θc. However, the operation mode may be changed as appropriate by taking into account the engine speed and the intake air temperature.

  In the second and fourth embodiments, the PCV opening VA increases as the cooling water temperature θ increases. However, the PCV opening VA increases as the elapsed time from the start of the engine increases. May be. Unlike the case where the cooling water is circulated, when the circulation of the cooling water is stopped, the gap between the cylinder bore 15 and the piston 17 increases, and the joint of the piston ring 17a also increases. The difference in the amount of thermal strain between both increases as the cooling water temperature θ increases, that is, as the elapsed time from the start of the internal combustion engine 10 increases. Therefore, the amount of blow-by gas leaking to the crankcase 13 increases as the elapsed time from the start of the internal combustion engine 10 increases. In this regard, according to the present embodiment, the PCV opening VA is increased as the elapsed time from the start of the engine becomes longer, so that such a stay of blow-by gas can be appropriately suppressed in the crankcase 13. become able to.

  In the above embodiment, an electric pump is used as the water pump 56, but an engine-driven water pump may be employed. In this case, the water pump is connected to a crankshaft (not shown) via a clutch, and the clutch is connected and disconnected to discharge cooling water (normal control mode) and stop the discharge. (Stop mode) is switched. In this case, for example, if the clutch is half-engaged or a speed reduction mechanism is provided in addition to the clutch, the operation in the extremely low flow rate mode is possible. Even in the case where such a water pump is employed, in the present embodiment, it is possible to achieve an operational effect similar to the above operational effect.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Cylinder block, 11a ... Communication path, 12 ... Cylinder head, 13 ... Crankcase, 14 ... Oil pan, 15 ... Cylinder bore, 16 ... Combustion chamber, 17 ... Piston, 17a ... Piston ring, 17b ... Expander, 17c ... ring groove, 18 ... cylinder head cover, 20 ... intake passage, 21 ... exhaust passage, 22 ... intake valve, 23 ... exhaust valve, 24 ... throttle valve, 40 ... blow-by gas recirculation device, 41 ... PCV valve, 42 ... recirculation passage, 43 ... fresh air introduction passage, 50 ... cooling device, 51 ... radiator, 52 ... water jacket, 53 ... cooling water passage, 55 ... bypass passage, 56 ... water pump, 57 ... thermostat, 91 ... electronic control Apparatus, 92 ... water temperature sensor, 93 ... rotational speed sensor.

Claims (7)

A control device for an internal combustion engine,
The internal combustion engine has an engine output shaft, an engine cooling system, a crankcase, an intake passage, a cooling device, and a blow-by gas recirculation device,
The cooling device has an electric water pump and a water temperature sensor,
The water pump has a structure capable of circulating cooling water in the engine cooling system and changing a discharge amount of the cooling water,
The water temperature sensor outputs a signal that changes according to the temperature of the cooling water to the control device,
The blow-by gas recirculation device has a communication path and a flow rate control valve,
The communication path connects the crankcase and the intake path to each other,
The flow control valve adjusts the flow rate of blow-by gas in the communication path,
The control device includes:
When the water temperature sensor signal indicates that the temperature of the cooling water during warming up of the internal combustion engine belongs to a range equal to or higher than a determination temperature, the water pump is operated,
When the signal of the water temperature sensor indicates that the temperature of the cooling water during warm-up of the internal combustion engine belongs to a range below the determination temperature, the operation of the water pump is stopped,
Based on operating the water pump, select a control method for controlling the opening of the flow control valve according to the output of a sensor indicating the operating state of the internal combustion engine,
The flow rate control valve is more than when the flow control valve is opened and the opening degree of the flow rate control valve is controlled by the control method based on stopping the operation of the water pump. A control device for an internal combustion engine that selects a control method for increasing the opening of the engine. A control device for an internal combustion engine,
The internal combustion engine has an engine output shaft, an engine cooling system, a crankcase, an intake passage, a cooling device, and a blow-by gas recirculation device,
The cooling device has a mechanical water pump, a clutch, and a water temperature sensor,
The water pump is driven by the engine output shaft, circulates cooling water in the engine cooling system,
The clutch connects or disconnects the water pump and the engine output shaft from each other,
The water temperature sensor outputs a signal that changes according to the temperature of the cooling water to the control device,
The blow-by gas recirculation device has a communication path and a flow rate control valve,
The communication path connects the crankcase and the intake path to each other,
The flow control valve adjusts the flow rate of blow-by gas in the communication path,
The control device includes:
When the signal of the water temperature sensor suggests that the temperature of the cooling water during warm-up of the internal combustion engine belongs to a range equal to or higher than a determination temperature, the water pump and the engine output shaft are controlled by controlling the clutch. By connecting to each other, the water pump is operated,
When the water temperature sensor signal indicates that the temperature of the cooling water during warm-up of the internal combustion engine falls below the determination temperature, the water pump and the engine output shaft are controlled by controlling the clutch. By cutting the water pumps from each other,
Based on operating the water pump, select a control method for controlling the opening of the flow control valve according to the output of a sensor indicating the operating state of the internal combustion engine,
The flow rate control valve is more than when the flow control valve is opened and the opening degree of the flow rate control valve is controlled by the control method based on stopping the operation of the water pump. A control device for an internal combustion engine that selects a control method for increasing the opening of the engine. Based on the fact that the operation of the water pump is stopped, the control device indicates the opening of the flow control valve when the flow control valve is in the open state by the signal of the water temperature sensor. The flow control valve is changed based on the temperature of the cooling water at the start of the internal combustion engine, and the opening degree of the flow rate control valve is increased as the temperature of the cooling water at the start of the internal combustion engine decreases.
The control apparatus for an internal combustion engine according to claim 1 or 2 . Based on the temperature of the cooling water suggested by the signal of the water temperature sensor when the control device is causing the flow rate control valve to open based on stopping the operation of the water pump. The opening degree of the flow control valve is changed, and the opening degree of the flow control valve is increased as the temperature of the cooling water increases.
The control device for an internal combustion engine according to any one of claims 1 to 3 . The control device is based on a length of a period during which the operation of the water pump is stopped when the flow control valve is in an open state based on the operation of the water pump being stopped. The opening degree of the flow control valve is changed, and the opening degree of the flow control valve is increased as the period becomes longer.
The control device for an internal combustion engine according to any one of claims 1 to 4 . The control device causes the flow rate control valve to form a fully open state based on stopping the operation of the water pump.
The control apparatus for an internal combustion engine according to claim 1 or 2 . The control device includes:
The temperature of the cooling water in the warm-up of the internal combustion engine reaches the determination temperature to rise, when it is suggested by the signal of the water temperature sensor, to start the operation of the water pump,
From the start of the operation of the water pump until the extremely low flow rate period elapses, let the water pump discharge the cooling water with an extremely low flow rate,
After the extremely low flow rate period has elapsed, the water pump is caused to discharge cooling water having a flow rate greater than the extremely low flow rate,
The opening degree of the flow rate control valve is increased after the extremely low flow rate period has elapsed from the start of the water pump operation until the extremely low flow rate period has elapsed.
The control device for an internal combustion engine according to any one of claims 1 to 6 .

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