JP2012026374A - Control device of onboard internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an onboard internal combustion engine that prevents oil consumption from increasing by the occurrence of an excessive oil loss via a piston ring, in an internal combustion engine that controls discharge of a pump in an engine cold state to perform warm-up promoting processing, when deceleration fuel-cut processing is performed during the warm-up promoting processing.SOLUTION: The control device 91 of the internal combustion engine 10 includes a water temperature sensor 92 for detecting a temperature of a coolant of a water jacket 13 as a coolant temperature θ. When the coolant temperature θ is less than an upper limit temperature θc, the warm-up promoting processing that limits the discharge of the pump 23 to a circulation channel 20 is performed. The internal combustion engine 10 also includes a throttle valve 35 which varies a negative pressure in an engine combustion chamber 14 during intake stroke. When the deceleration fuel-cut processing is carried out during the warm-up promoting processing, the control device 91 controls the throttle valve 35 so that the negative pressure is reduced in comparison with when the warm-up promoting processing is not performed.

Description

  The present invention has a pump that can appropriately change the discharge amount of cooling water, such as an electric rotary pump, and performs warm-up promotion processing that promotes warm-up by limiting the discharge amount of the pump when the engine is cold In addition, the present invention relates to a control apparatus for an in-vehicle internal combustion engine that controls a negative pressure generated in an engine combustion chamber based on an execution mode of the warm-up promotion process.

  Normally, when the vehicle is decelerated, the internal combustion engine is controlled until the accelerator operation is released and the throttle valve is closed so that the throttle valve is fully closed. The fuel cut process at the time of deceleration is executed to temporarily stop the fuel injection. When such a fuel cut process during deceleration is executed, a large negative pressure is generated in the engine combustion chamber, so that the oil adhering to the piston, cylinder bore, etc. A phenomenon that flows into the inside, so-called oil rise, occurs. When such an oil rise occurs, the oil flowing into the engine combustion chamber is burned together with the air-fuel mixture and discharged to the outside, leading to an increase in oil consumption. Therefore, conventionally, when performing the fuel cut process at the time of deceleration, the throttle valve opening is not fully closed, but is controlled to an opening that can suppress the occurrence of such oil rise. (For example, refer to Patent Document 1).

  In recent years, as a pump that circulates cooling water in a circulation channel of an internal combustion engine, a cooling device that employs an electric rotary pump instead of a conventional engine-driven pump has been proposed. In such a cooling device, the pump is stopped until the temperature of the cooling water staying around the cylinder bore of the internal combustion engine reaches a predetermined temperature. That is, the circulation of the cooling water in the circulation channel is prohibited to temporarily reduce the cooling capacity of the cooling device, thereby promoting the warm-up of the internal combustion engine (hereinafter referred to as “warm-up promotion process”). . And even when the engine is cold, the cooling water staying around the cylinder bore quickly becomes high temperature due to the heat generated in the engine combustion chamber, which can promote warm-up, reduce heat loss, As a result, fuel consumption can be improved (see, for example, Patent Document 2).

JP-A-2005-147909 JP 2008-169750 A

  In general, when the air-fuel mixture burns in the engine combustion chamber, the temperature of both the piston and the cylinder bore rises due to the combustion heat, and thermal expansion occurs accordingly. However, the cylinder bore has a higher temperature change rate due to combustion heat than the piston, and also has a large amount of heat exchange with the cooling water. In an internal combustion engine, in consideration of these points in advance, the pump is operated so that the cooling water is circulated in the circulating water path so that the clearance between the piston and the cylinder bore is substantially constant, that is, the time taken during engine operation. The specifications of the piston and cylinder bore are set in advance in accordance with the situation where there are the most. For this reason, even when the fuel cut processing at the time of deceleration is executed, excessive oil rise occurs by adjusting the throttle valve opening so that excessive negative pressure does not occur in the engine combustion chamber Can be avoided.

However, the present inventor has obtained knowledge that the following inconvenience may occur when the fuel cut process during deceleration as described above is executed during the execution of the warm-up promotion process.
That is, during the warm-up promotion process, the flow of cooling water in the circulation channel does not occur, so the amount of heat exchange between the cylinder bore and the cooling water is smaller than when the pump is operating. On the other hand, since the amount of heat exchange between the piston and the cooling water is small in the first place, the amount of heat exchange caused by the execution of the warm-up acceleration process that occurs in the cylinder bore is extremely small for the piston. . Further, the cylinder bore has a higher temperature change rate due to combustion heat than the piston. For this reason, during the warm-up promotion process, only the cylinder bore is locally thermally deformed, so that the inner diameter of the cylinder bore is greatly expanded relative to the outer diameter of the piston. In the normal operation, that is, when the warm-up promotion process is not executed, a clearance that cannot be generated occurs.

  When the fuel cut process during deceleration is performed during the warm-up promotion process, a large amount of oil flows into the engine combustion chamber through the clearance between the piston and the cylinder bore, particularly through the joint portion of the piston ring. Become. In this case, as described above, the throttle valve opening is controlled to suppress the oil rise, but the control assumes a state where the pump is stopped and the cooling water is not circulated in the circulation channel. Therefore, during the warm-up promotion process, there is a risk that the oil will rise to a degree that cannot be dealt with by such control.

  The present invention has been made on the basis of the knowledge obtained by the inventor as described above, and an object of the present invention is to improve the warm-up in an internal combustion engine that executes a warm-up promotion process by limiting the pump discharge amount when the engine is cold. To provide a control device for an in-vehicle internal combustion engine capable of suppressing an increase in oil consumption due to an excessive amount of oil rising when a fuel cut process during deceleration is performed during the execution of an acceleration process. It is in.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 includes a sensor for detecting the temperature of the cooling water around the cylinder bore, and the temperature of the detected cooling water is less than a predetermined upper limit temperature at least as an execution condition for the circulating water channel. A negative pressure variable means capable of changing a negative pressure of an engine combustion chamber in an intake stroke in a control device of an on-vehicle internal combustion engine provided with a cooling device for controlling the pump so as to execute a warm-up promotion process for limiting a discharge amount of the pump The negative pressure variable means is controlled so that the negative pressure is reduced when the fuel cut during deceleration is performed during the warm-up promotion process compared to when the warm-up promotion process is not performed. And a control means.

  According to this configuration, since the negative pressure generated in the engine combustion chamber when the fuel cut process during deceleration is executed during the warm-up acceleration process is performed, the oil flows through the joint of the piston ring. Occurrence of oil rising sucked into the engine combustion chamber can be suppressed, and an increase in oil consumption can be suppressed.

  According to a second aspect of the present invention, in the control device for an on-vehicle internal combustion engine according to the first aspect, the control means is configured such that the negative pressure is lower than when the detected coolant temperature around the cylinder bore is high. The gist is to set the reduction amount when reducing the value to a large value.

  During the execution of the warm-up promotion process, as the temperature of the cooling water around the cylinder bore increases, that is, as the temperature of the cooling water approaches the upper limit temperature, the above-described local deformation of the cylinder bore becomes remarkable. Furthermore, the higher the temperature of the cooling water around the cylinder bore, the lower the oil viscosity and the higher the fluidity. Therefore, when the temperature of the cooling water around the cylinder bore is high as described above, it is desirable to greatly reduce the negative pressure in the engine combustion chamber in order to suppress the increase in oil consumption caused by the oil rise as described above. However, if the negative pressure in the engine combustion chamber is greatly reduced in this way, the pumping loss will decrease even though the fuel cut process at the time of deceleration is executed, so the vehicle's feeling of deceleration during normal operation It may be lower than that of the driver and may give the driver an uncomfortable feeling.

  In this regard, in this configuration, the amount of decrease when the negative pressure is decreased is variably set according to the temperature of the cooling water around the cylinder. That is, when the temperature of the cooling water around the cylinder bore is high, the amount of decrease when the negative pressure in the engine combustion chamber is reduced is increased. Therefore, the occurrence of such oil rise depends on the temperature of the cooling water around the cylinder bore. It can be appropriately suppressed in a form. On the other hand, when the temperature of the cooling water around the cylinder bore is low, such as when the engine is cold, that is, when the oil rise is not so noticeable, the amount of decrease when reducing the negative pressure is reduced, so that the vehicle deceleration It is possible to suppress a feeling that is unnecessarily lowered and give the driver an uncomfortable feeling. As described above, according to the above configuration, it is possible to reduce the uncomfortable feeling as described above while appropriately suppressing an increase in oil consumption.

  According to a third aspect of the present invention, there is provided a control device for an on-vehicle internal combustion engine according to the first or second aspect, wherein the control means has a longer elapsed time after the fuel cut at the time of deceleration is shorter than a longer time. The gist is to set the amount of decrease when the negative pressure is decreased to a large value.

  The engine speed immediately after the fuel cut process at the time of deceleration is relatively high compared to the engine speed immediately before stopping, so the negative pressure generated in the engine combustion chamber is large and the oil rises easily. There is a tendency. In this regard, according to the above-described configuration, the amount of decrease when the negative pressure in the engine combustion chamber is reduced is increased as the elapsed time after the fuel cut processing at the time of deceleration is shorter. This can be appropriately suppressed in accordance with the rising situation.

  As described in the fourth aspect of the present invention, the negative pressure in the engine combustion chamber is set, for example, by increasing the throttle valve opening, thereby reducing the amount of intake air flowing into the engine combustion chamber. By increasing it, the negative pressure generated in the engine combustion chamber can be reduced. Alternatively, as in the fifth aspect of the invention, if the internal combustion engine has a lift amount changing mechanism capable of changing the lift amount of the intake valve, it flows into the engine combustion chamber by increasing the lift amount of the intake valve. It is also possible to reduce the negative pressure in the engine combustion chamber by increasing the amount of intake air. Alternatively, as in the sixth aspect of the invention, if the internal combustion engine includes a valve timing changing mechanism that changes the valve timing of at least one of the intake valve and the exhaust valve, the valve timing of at least one of the intake valve and the exhaust valve. By increasing the valve overlap amount through this change, the exhaust gas blown back to the engine combustion chamber can be increased to reduce the negative pressure in the engine combustion chamber. In addition, according to the invention of claim 7, there is provided an external EGR device having a communication passage communicating the exhaust passage and the intake passage and a metering valve for metering exhaust gas returned from the exhaust passage to the intake passage through the communication passage. In the case of an internal combustion engine having the above, the negative pressure in the engine combustion chamber may be reduced by increasing the amount of exhaust gas returned from the exhaust passage to the intake passage by increasing the opening of the metering valve. Good.

  The invention according to claim 8 is the control device for an on-vehicle internal combustion engine according to any one of claims 1 to 7, wherein the control means has a predetermined period after the warm-up promotion processing is completed. The gist of the present invention is to control the variable negative pressure means so that the negative pressure is reduced as compared with the case where the warm-up promotion process is not executed.

  As described above, during the warm-up promotion process, the local deformation of the cylinder bore increases as the temperature of the cooling water around the cylinder bore increases. Immediately before the end of the warm-up promotion process, the temperature of the cooling water around the cylinder bore becomes extremely high, and local deformation of the cylinder bore becomes remarkable. After that, when the warm-up promotion process is completed, circulation of the cooling water is started, so that the local deformation of the cylinder bore is gradually relieved, but the clearance between the piston and the cylinder bore is reduced during normal operation. It takes a predetermined time to become the same state. Therefore, even after the warm-up promotion process is completed, the period until the clearance between the piston and the cylinder bore becomes the same state as that during normal operation as described above is Similarly, there is a concern about an increase in oil consumption accompanying the oil increase. However, if the conditions for executing the warm-up promotion process are not satisfied and the warm-up promotion process is not executed in the first place, the clearance between the piston and the cylinder bore is naturally in the same state as during normal operation. The excessive oil rise as described above does not occur.

  In this regard, according to the above configuration, after the warm-up promotion process is completed, until the local deformation of the cylinder bore associated with the execution of the warm-up promotion process is reduced to a negligible level, Similarly, since the negative pressure generated in the engine combustion chamber is reduced, an increase in oil consumption can be appropriately suppressed.

  According to a ninth aspect of the present invention, in the control device for an in-vehicle internal combustion engine according to the eighth aspect, the control means reaches the predetermined amount after the completion of the warm-up promoting process. The gist is to set the above engine as the predetermined period.

  The predetermined period for reducing the negative pressure in the engine combustion chamber in this way may be a fixed value set in advance. However, the increase in oil due to the local deformation of the cylinder bore has not been sufficiently relaxed. In order to suppress appropriately, as described in claim 9, the pump discharge amount after the completion of the warm-up promotion process is monitored each time until the integrated value reaches a predetermined amount, that is, the cylinder bore It is desirable to execute a process for reducing the negative pressure in the engine combustion chamber, with the period during which a sufficient amount of cooling water is circulated to alleviate local deformation as the predetermined period.

  A tenth aspect of the present invention is the control system for an on-vehicle internal combustion engine according to any one of the first to ninth aspects, wherein the vehicle on which the internal combustion engine is mounted also includes a motor generator as a drive source thereof. The gist of the invention is that the control means controls the regenerative braking force by the motor generator to be increased when the negative pressure variable means is controlled so that the negative pressure decreases.

  As described above, if the negative pressure in the engine combustion chamber is reduced during execution of the deceleration fuel cut processing, the pumping loss is reduced, so that the feeling of deceleration of the vehicle is reduced as compared with the normal operation, and the driver May give a sense of incongruity. In this respect, according to the same configuration, the reduction in the deceleration feeling associated with the reduction in the pumping loss can be compensated by the increase in the regenerative braking force, and the reduction in the deceleration feeling associated with the decrease in the negative pressure in the engine combustion chamber is alleviated. can do.

1 is a schematic configuration diagram showing an internal combustion engine and a cooling device thereof according to an embodiment of the present invention. (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 schematic block diagram which shows the schematic structure about the drive system of the hybrid vehicle concerning the embodiment. The flowchart which shows the process sequence about control of the pump concerning the embodiment. 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 control of the throttle valve concerning the embodiment. An arithmetic map showing the relationship between the coolant temperature and the target throttle opening correction amount. The calculation map which shows the relationship between the elapsed time from the time of the fuel cut process start at the time of deceleration, and the correction amount of target throttle opening. (A) Accelerator operation amount, (b) Execution mode of fuel cut process at deceleration, (c) Engine rotation speed, (d) Timing chart showing an example of transition of throttle opening.

  A vehicle internal combustion engine control apparatus according to an embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 3, the vehicle on which the internal combustion engine 10 is mounted further includes a motor generator 62 as a driving source in addition to the internal combustion engine 10, and the internal combustion engine 10, the motor generator 62, Thus, the vehicle is a so-called hybrid vehicle that travels by appropriately distributing the driving force required according to the traveling state of the vehicle.

  First, the internal combustion engine 10 and its cooling device will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, a plurality of cylinder bores 15 (only one of which is shown in FIG. 1) are formed in the cylinder block 11 of the internal combustion engine 10, and pistons 17 are disposed inside the cylinder bores 15. It is provided so that it can reciprocate. In the internal combustion engine 10, a plurality of engine combustion chambers 14 (only one of which is shown in FIG. 1) are defined by the cylinder bore 15, the cylinder head 12, the piston 17, and the like of the cylinder block 11. Is formed with a water jacket 13 through which cooling water circulates.

  An intake passage 31 and an exhaust passage 32 are connected to the engine combustion chamber 14. In addition to the fuel injection valve 16 that injects fuel into the engine combustion chamber 14, the cylinder head 12 includes an intake valve 33 that communicates and blocks the engine combustion chamber 14 and the intake passage 31, and the engine combustion chamber 14 and the exhaust passage 32. And an exhaust valve 34 that communicates with and shuts off each other.

  The intake valve 33 and the exhaust valve 34 are respectively provided with variable valve mechanisms 51 and 52 that change their drive modes. The intake valve 33 and the exhaust valve 34 are driven to open and close with a predetermined lift profile by these variable valve mechanisms 51 and 52. Specifically, the operating angle (opening period) and the maximum lift amount of the intake valve 33 are changed by the variable valve mechanism 51, while the operating angle (opening period) and the maximum lift amount of the exhaust valve 34 are variable. It is changed by the valve mechanism 52. Further, through the change of the lift profiles of the intake valve 33 and the exhaust valve 34, the period during which the valves 33 and 34 are simultaneously opened, that is, the valve overlap amount can be changed together.

  The intake passage 31 is provided with an electronically controlled throttle valve 35. The throttle valve 35 has its opening degree (hereinafter referred to as “throttle opening THA”) adjusted by a motor (not shown), whereby the amount of intake air flowing into the engine combustion chamber 14 is controlled by the intake valve 33. Adjustment is performed in cooperation with the variable valve mechanism 51.

  On the other hand, the exhaust passage 32 is provided with an EGR device 40 for recirculating exhaust gas from the exhaust passage 32 to the intake passage 31 to perform exhaust gas recirculation. The EGR device 40 branches from the exhaust passage 32 and is connected to the downstream side of the throttle valve 35 of the intake passage 31 and adjusts the flow rate of the exhaust gas recirculating through the EGR passage 41 according to the opening degree. EGR valve 42 is provided. A part of the exhaust gas flowing through the exhaust passage 32 is returned to the intake passage 31 by the EGR device 40, so that NOx in the exhaust gas can be reduced.

  In addition, an oil pan 18 in which oil is stored is assembled at the lower part of the cylinder block 11. The oil pan 18 stores oil for lubricating or cooling each sliding portion of the internal combustion engine 10 and driving hydraulic equipment of the internal combustion engine 10 as hydraulic oil. This oil is discharged by an oil pump (not shown) and supplied to a necessary portion through a lubricating oil passage (not shown). In particular, a large amount of oil is injected and supplied to the piston 17 and the cylinder bore 15 and the sliding surfaces thereof via an oil jet (not shown) to be used for lubrication and cooling.

  Further, three ring grooves 17c are formed on the outer peripheral surface of the piston 17, and as shown in FIG. 2A, the airtightness of the engine combustion chamber 14 and the cylinder bore 15 are secured in the ring grooves 17c. A plurality of piston rings 17a are respectively attached for the purpose of forming an appropriate oil film on the inner peripheral 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. 2B, the piston ring 17a is formed with an abutment for facilitating the mounting operation with respect to the ring groove 17c.

  Since the piston ring 17a is pressed against the inner peripheral surface of the cylinder bore 15 by the expander 17b, the inner diameter of the cylinder bore 15 is relatively increased with respect to the outer diameter of the piston 17 by the combustion heat of the engine combustion chamber 14. Even in the case of a diameter, the piston ring 17a can maintain a state in which the piston bore 17a is in contact with the inner peripheral surface following the expansion of the inner diameter of the cylinder bore 15. In this case, the joint of the piston ring 17a expands.

  Next, a cooling device for such an internal combustion engine 10 will be described. The cooling water passage 20 of the cooling device is roughly composed of a radiator passage 22 for returning cooling water flowing out from the water jacket 13 to the thermostat 24 via the radiator 25 in addition to the water jacket 13 as described above, and the radiator passage 22. The bypass 25 is connected to the thermostat 24 so as to bypass the radiator 25, and includes a bypass passage 21 that directly returns the cooling water flowing out from the water jacket 13 to the thermostat 24.

  The thermostat 24 adjusts the flow rate of the cooling water flowing through the radiator passage 22 according to the opening degree. That is, when the temperature of the cooling water in contact with the temperature sensing portion of the thermostat 24 is lower than the valve opening temperature, the thermostat 24 is in a closed state, so that the cooling water flowing out of the water jacket 13 flows into the radiator 25. All flow into the bypass passage 21 without any change. On the other hand, when the temperature of the cooling water in contact with the temperature sensing portion of the thermostat 24 becomes higher than the valve opening temperature, the thermostat 24 is opened, so that the cooling water flowing out of the water jacket 13 is added to the bypass passage 21 and the radiator. 25 also flows in. And the cooling water which flowed into the radiator 25 in this way is cooled through heat exchange with outside air.

  A pump 23 for circulating cooling water through the circulation channel 20 is provided in the middle of the circulation channel 20. The pump 23 is an electric rotary pump that uses a motor (not shown) as a drive source. The higher the rotational speed of the motor, that is, the rotational speed of the pump 23, the greater the discharge amount. The rotational speed of the pump 23 is changed by duty-controlling the supply voltage of the motor. That is, as the duty ratio D increases, the power supplied to the pump 23 increases and the amount of cooling water discharged by the pump 23 increases.

The drive states of the variable valve mechanisms 51 and 52, the fuel injection valve 16, the throttle valve 35, the pump 23, and the EGR valve 42 are all controlled by the control device 91.
The internal combustion engine 10 is equipped with various sensors for detecting the operating state of the engine including auxiliary machines. For example, a water temperature sensor 92 that detects the temperature of the cooling water is attached to the cylinder head 12 at the most downstream portion of the water jacket 13. In the cooling device, the temperature of the cooling water detected by the water temperature sensor 92 is used as an alternative value for the temperature of the cooling water staying around the cylinder bore 15, that is, in the water jacket 13 (hereinafter referred to as “cooling water temperature θ”). Further, a crank angle sensor 93 for detecting the rotation speed, that is, the engine rotation speed NE is provided in the vicinity of the crankshaft 19. In addition, an accelerator sensor 94 for detecting an operation amount (depression amount) ACCP is provided in the vicinity of an accelerator pedal (not shown). The control device 91 takes in the detection values of these various sensors, and executes control such as variable valve control, fuel injection control, throttle opening control, EGR control and the like based on the detection values of these sensors.

  As described above, the vehicle according to the present embodiment includes the motor generator 62 as a drive source in addition to the internal combustion engine 10. As shown in FIG. 3, the driving forces of the output shafts of the internal combustion engine 10 and the motor generator 62 are input to the power split mechanism 61 and transmitted to the drive wheels via the speed reduction mechanism 65. The motor generator 62 is electrically connected to the battery 64 via the power control device 63, and generates driving force when electric power is supplied from the battery 64. In addition to the function of converting electric energy into kinetic energy, the motor generator 62 regenerates the kinetic energy of the vehicle as electric energy when the vehicle decelerates, and controls the electric energy thus regenerated. Electric power is stored in the battery 64 through the device 63. In this vehicle, depending on the current driving conditions such as the acceleration request, the amount of power stored in the battery 64, etc., traveling by only the motor generator 62, traveling only by the internal combustion engine 10, and traveling by the motor generator 62 and the internal combustion engine 10. Are switched appropriately.

  By the way, after the engine is started, it is desirable to complete the warm-up of the internal combustion engine 10 at an early stage in order to improve fuel consumption and combustion stability. Therefore, in the present embodiment, the operation of the pump 23 is stopped until the warm-up of the internal combustion engine 10 is completed, and a process of prohibiting the circulation of the cooling water in the circulation water channel 20 (a warm-up promoting process) is performed. Yes.

  Hereinafter, with reference to FIG. 4, the specific process sequence of such a warm-up promotion process is demonstrated. The control device 91 repeatedly executes the series of processes shown in FIG. 4 every predetermined time period ΔT. In addition, by integrating the flow rate q corresponding to the duty ratio D of the pump 23 in each control cycle and the predetermined time ΔT, the cooling water flowing through the circulation channel 20 from the current control cycle to the next control cycle. Can be calculated. Further, the discharge amount integrated value ΣQ of the pump 23 can be calculated by sequentially integrating the flow rate Q for each control cycle.

  First, the control device 91 determines whether or not the cooling water temperature θ detected by the water temperature sensor 92 is less than the upper limit temperature θc (step S100). The upper limit water temperature θc is based on a comparison with the cooling water temperature θ that the internal combustion engine 10 is not sufficiently warmed up and it is not necessary to circulate the cooling water to cool the internal combustion engine 10. This is a value for determination and is determined in advance through a test or the like. When it is determined that the cooling water temperature θ is equal to or higher than the upper limit water temperature θc (step S100: NO), that is, when it is determined that the warm-up of the internal combustion engine 10 is almost completed, it is not necessary to execute the warm-up promotion process. Therefore, the pump 23 shifts to normal operation (step S120). Thus, when it transfers to a normal driving | operation, the pump 23 is controlled based on engine operating conditions, such as engine load and engine speed NE.

  On the other hand, when it is determined that the cooling water temperature θ is lower than the upper limit water temperature θc (step S100: YES), a warm-up promotion process for stopping the operation of the pump 23 is executed (step S110). That is, the operation of the pump 23 is stopped, the cooling capacity of the cooling device is lowered, and warming up of the internal combustion engine 10 is promoted.

  By the way, during the execution of the warming-up promotion process, the following phenomenon that is not observed during normal pump operation occurs with respect to the clearance between the piston 17 and the cylinder bore 15. FIG. 5 shows the relationship between the clearance CL between the piston 17 and the cylinder bore 15 located between the joints of the piston ring 17a during and after execution of the warm-up promotion process, and the cooling water temperature θ. In FIG. 5, the transition of the inner diameter of the cylinder bore 15 when the pump 23 is normally operated, that is, when the warm-up promotion process is not executed, is indicated by a broken line.

  When the air-fuel mixture burns in the engine combustion chamber 14, the cooling water temperature θ rises due to the combustion heat. Moreover, since both the piston 17 and the cylinder bore 15 rise in temperature due to this combustion heat, both the outer diameter of the piston 17 and the inner diameter of the cylinder bore 15 are expanded by thermal expansion. 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, the pump 23 is normally operated so that the clearance CL (= CL1) between the piston 17 and the cylinder bore 15 becomes substantially constant, that is, during engine operation. The specifications of the piston 17 and the cylinder bore 15 are set in advance in accordance with the situation where the time occupied by is the largest.

  However, when the operation of the pump 23 is stopped along with the execution of the warm-up promotion process, the circulation of the cooling water does not occur in the circulation water channel 20, so that the cylinder bore 15 and the cooling water are more separated than when the pump 23 is normally operated. The amount of heat exchange between them will decrease. On the other hand, since the amount of heat exchange between the piston 17 and the cooling water is small in the first place, regarding the piston 17, the amount of heat exchange caused by the execution of the warm-up acceleration process that occurs in the cylinder bore 15 is performed. There is little change (in FIG. 5, it is assumed that the change can be ignored). For this reason, during execution of the warm-up promotion process, the inner diameter of the cylinder bore 15 is greatly expanded with respect to the outer diameter of the piston 17, and the clearance CL (= CL2) between the piston 17 and the cylinder bore 15 is The size cannot be generated during normal operation. Furthermore, not only the clearance CL but also the gap at the joint increases as the diameter of the cylinder bore 15 increases.

  Also, as shown in FIG. 5, the inner diameter of the cylinder bore 15 increases as the cooling water temperature θ increases, that is, as the cooling water temperature θ approaches the upper limit water temperature θc. For this reason, the clearance CL between the piston 17 and the cylinder bore 15 increases as the coolant temperature θ increases. Thereafter, when the cooling water temperature θ reaches the upper limit water temperature θc at which the warm-up promotion processing ends and the circulation of the cooling water by the pump 23 is started, heat exchange between the cylinder bore 15 and the cooling water is promoted, and therefore the cylinder bore 15 The inner diameter of the is gradually reduced. Thereby, the clearance CL between the piston 17 and the cylinder bore 15 is gradually reduced. That is, the clearance CL between the piston 17 located between the joints of the piston ring 17a and the cylinder bore 15 is gradually reduced.

  Here, when the clearance CL between the piston 17 located between the joints of the piston ring 17a and the cylinder bore 15 is increased with the execution of the warm-up promotion process, and the gap between the joints is enlarged. When the fuel cut process at the time of deceleration is performed, the amount of oil that is sucked into the engine combustion chamber 14 through this clearance CL increases, and a situation that can no longer be dealt with by the normally assumed suppression process of oil rise occurs. The points are as described above.

  Therefore, in the present embodiment, during the warm-up promotion process and during a predetermined period after the end of the warm-up promotion process, the normal operation of the pump 23 is performed to reduce the negative pressure generated in the engine combustion chamber 14. In comparison, negative pressure reduction processing is performed to correct the throttle opening THA so as to increase. Hereinafter, with reference to FIG. 6, a specific processing procedure of drive control of the throttle valve 35 in the case where such warm-up promotion processing and negative pressure reduction processing are executed will be described. Note that the control device 91 repeatedly executes this processing every predetermined calculation cycle.

  First, the control device 91 determines whether or not the accelerator operation has been released (step S200). That is, it is determined whether or not the accelerator operation amount ACCP is “0”. If it is determined that the accelerator operation is not released (step S200: NO), the variable valve mechanism 51 of the throttle valve 35 and the intake valve 33 shifts to normal control (step S260). That is, the throttle opening THA and the maximum lift amount of the variable valve mechanism 51 are basically set according to the accelerator pedal operation amount ACCP.

  On the other hand, when it is determined that the accelerator operation has been released (step S200: YES), a fuel cut process during deceleration is executed (step S210). Specifically, the fuel injection is temporarily stopped until the engine rotational speed NE decreases to a rotational speed (fuel cut return rotational speed NEc) set in consideration of the occurrence of engine stall. And the process which increases throttle opening THA to the grade which can suppress generation | occurrence | production of an oil rise is performed.

  Next, the target throttle opening THAt is set according to the engine operating state of the internal combustion engine 10 including the auxiliary machine (step S220). Specifically, when an auxiliary machine such as a heating device (not shown) is driven, the target throttle opening THAt is set so as to increase as the load increases. Further, the target throttle opening THAt is set to be larger as the engine speed NE at the start of the fuel cut process at the time of deceleration is higher. This is because when the engine rotational speed NE is in a high state, the throttle opening THA is rapidly decreased to prevent a large negative pressure from being suddenly generated in the engine combustion chamber 14.

  When the target throttle opening THAt is thus set, it is next determined whether the warm-up promotion process is being executed or whether the predetermined period T has elapsed after the completion of the warm-up promotion process (step S230). . The predetermined period T is a period from the end of the warm-up promotion process until the discharge amount integrated value ΣQ of the pump 23 reaches the predetermined amount Q1. Then, the predetermined amount Q1 is reduced to such an extent that local deformation on the cylinder bore 15 can be ignored if the discharge amount integrated value ΣQ of the pump 23 after the warm-up promotion processing has reached the predetermined amount Q1. This is an expected amount.

  Then, when it is determined that the warm-up promotion process is being executed, or the predetermined period T has not elapsed after the completion of the warm-up promotion process (step S230: YES), the target throttle opening THAt is then increased. Correction is performed (step S240). That is, first, referring to the calculation map shown in FIG. 7, the correction amount α of the target throttle opening THAt is calculated according to the cooling water temperature θ.

  FIG. 7 is a calculation map showing the relationship between the coolant temperature θ and the correction amount α of the target throttle opening THAt. As shown in FIG. 7, the correction amount α of the target throttle opening THAt is set so as to increase as the cooling water temperature θ increases. Since the inner diameter of the cylinder bore 15 increases as the cooling water temperature θ increases, the clearance CL between the outer diameter of the piston 17 and the inner diameter of the cylinder bore 15 increases. For this reason, it is because it is thought that the clearance CL between the piston 17 located between the joints of the piston ring 17a and the cylinder bore 15 expands, and oil rise becomes remarkable.

  Next, referring to the calculation map shown in FIG. 8, the correction amount β of the target throttle opening THAt is calculated according to the elapsed time from the start of deceleration fuel cut processing. FIG. 8 is a calculation map showing the relationship between the elapsed time from the start of deceleration fuel cut processing and the correction amount β of the target throttle opening THAt. As shown in FIG. 8, the correction amount β of the target throttle opening THAt is set so as to decrease as the elapsed time from the start of the fuel cut process at the time of deceleration becomes longer. Since the engine speed NE immediately after the fuel cut process at the time of deceleration is relatively high compared to the engine speed NE immediately before stopping, a large negative pressure is generated in the engine combustion chamber 14 and the oil This is because the oil consumption due to the rise tends to increase. 7 and 8 are obtained in advance through experiments or the like and stored in the memory 91a of the control device 91.

  After calculating the correction amount α and the correction amount β in this way, the correction amount α and the correction amount β are added to the target throttle opening degree THAt set in the previous step S220 to increase the target throttle opening degree THAt. (Step S240).

  Next, the throttle valve 35 is controlled so that the throttle opening THA becomes the target throttle opening THAt (step S250), and this process is temporarily ended. Further, when it is determined that the warm-up promotion process is not being executed or after the predetermined period T has elapsed after the completion of the warm-up promotion process (step S230: NO), the target throttle opening THAt is increased. Without correction, the throttle valve 35 is controlled so that the throttle opening THA becomes the target throttle opening THAt (step S250), and this process is temporarily terminated.

  FIG. 9 shows (a) accelerator operation amount ACCP, (b) execution mode of fuel cut processing during deceleration, and (c) engine rotation when such warm-up promotion processing and negative pressure reduction processing are executed from the start of the engine. Changes in speed NE and (d) throttle opening THA are shown. A solid line, a single point, and a two-dot chain line show typical examples when the cooling water temperature θ is different for each transition of the throttle opening THA. Specifically, when the cooling water temperature θ is low, such as when the engine is cold, the solid line is when the cooling water temperature θ is high to some extent, such as when the cooling water temperature θ is restarted after the warm-up has progressed to some extent, the two-dot chain line indicates the internal combustion engine 10 shows changes in the throttle opening THA when the cooling water temperature θ is extremely high, such as during a high-temperature restart after the warm-up of 10 is almost completed. The broken line indicates the transition of the throttle opening THA when such negative pressure reduction processing is not executed. That is, the transition is shown when normal oil rising is considered but excessive oil rising due to the local deformation of the cylinder bore 15 as described above is not considered.

For example, when the accelerator operation amount ACCP increases after the engine is started, the engine speed NE and the throttle opening THA also increase accordingly (timing t0 to t1). Of course, in this case, the fuel cut process during deceleration is not executed. When the accelerator operation amount ACCP is maintained at a predetermined amount, the engine rotational speed NE gradually increases, and accordingly, the throttle opening THA also gradually increases (timing t1 to t2).
When the accelerator operation is released, that is, when the accelerator operation amount becomes “0”, the deceleration fuel cut process is started (timing t2). At this time, the throttle opening THA greatly decreases. However, the throttle opening THA at this time is corrected to increase the target throttle opening THAt set according to the engine operating state including the engine speed NE including the auxiliary machine based on the correction amount α and the correction amount β. Opening. Specifically, as shown in FIG. 9D, the target throttle opening THAt increases as the coolant temperature θ increases and as the elapsed time from the start of the fuel cut process during deceleration decreases. This is corrected so that As a result, the throttle opening THA gradually decreases to a predetermined opening at which idle operation is possible. Further, when the engine rotational speed NE reaches the fuel cut return rotational speed NEc, the deceleration fuel cut process is stopped and fuel injection is started (timing t4).
As described above, according to the present embodiment, the following effects can be achieved.

  (1) According to the present embodiment, when the fuel cut process during deceleration is executed during the warm-up promotion process, the negative pressure generated in the engine combustion chamber 14 is reduced. It is possible to suppress the occurrence of oil rising where oil is sucked into the engine combustion chamber 14 through the joint 17a. For this reason, even during the execution of the warm-up promotion process, it is possible to suppress an increase in oil consumption accompanying the increase in oil.

  (2) The correction amount α is increased as the cooling water temperature θ is higher. For this reason, during the warm-up promotion process, the coolant temperature θ rises and local deformation of the cylinder bore 15 becomes prominent, and the oil viscosity decreases and its fluidity increases. In addition, the negative pressure in the engine combustion chamber 14 can be greatly reduced, and an increase in oil consumption due to oil rising can be appropriately suppressed in accordance with the cooling water temperature θ. On the other hand, when the cooling water temperature θ is low, such as when the engine is cold, that is, when the oil rise is not so significant, the correction amount α is reduced, so that the fuel cut process at the time of deceleration is being executed. By reducing the pumping loss, it is possible to suppress a feeling of deceleration of the vehicle compared to that during normal driving, and to prevent the driver from feeling uncomfortable.

  (3) Since the engine speed NE immediately after the fuel cut process at the time of deceleration is relatively high compared to the engine speed NE immediately before stopping, a large negative pressure is applied to the engine combustion chamber 14. Occurring and the oil consumption due to oil rise tends to increase. According to the present embodiment, since the correction amount β is increased as the elapsed time after the fuel cut process at the time of deceleration is shortened, the increase in oil consumption due to such oil rise is reduced. It becomes possible to suppress appropriately in the form corresponding to the elapsed time since.

  (4) During execution of the warm-up promotion process, the local deformation of the cylinder bore 15 increases as the coolant temperature θ increases. And just before the end of the warm-up promotion process, the coolant temperature θ becomes extremely high, and the local deformation of the cylinder bore 15 becomes remarkable. After that, when the warm-up promotion processing is completed, the circulation of the cooling water is started. Therefore, although the local deformation of the cylinder bore 15 is gradually eased, the clearance between the piston 17 and the cylinder bore 15 is normal. It takes a predetermined time to be in the same state as during operation. Therefore, even after the warm-up promotion process is completed, the warm-up promotion process is performed during the period until the clearance between the piston 17 and the cylinder bore 15 becomes the same as that during normal operation. Like the inside, there is a concern that the oil consumption will increase as the oil goes up. According to this embodiment, after the completion of the warm-up promotion process, the period until the local deformation of the cylinder bore 15 associated with the execution of the warm-up promotion process is reduced to a negligible level (predetermined period T) is negative pressure. Since the reduction process is executed, it is possible to appropriately suppress an increase in oil consumption.

  (5) Further, the pump discharge amount after completion of the warm-up promotion process is monitored each time until the integrated value reaches a predetermined amount, that is, the amount that local deformation of the cylinder bore 15 is reduced. A period until the cooling water is circulated is set as a predetermined period T, and the negative pressure reduction process is executed during this period. For this reason, it becomes possible to appropriately suppress an increase in oil consumption due to the local deformation of the cylinder bore 15 not being sufficiently relaxed.

  In addition, this invention is not restricted to the aspect illustrated in the said embodiment, For example, this can also be changed and implemented as shown below. The following modifications are not applied only to the above-described embodiments, and can be implemented in a mode in which different modifications are appropriately combined.

  -This may be controlled so that the regenerative braking force by the motor generator 62 increases in conjunction with the execution of the negative pressure reduction process. That is, as described above, when the negative pressure of the engine combustion chamber is reduced during the deceleration fuel cut process, the pumping loss is reduced, so that the feeling of deceleration of the vehicle is reduced as compared with that during normal operation. There is a risk of discomfort to the driver. In this respect, according to the same configuration, the reduction in the deceleration feeling associated with the reduction in the pumping loss can be compensated by the increase in the regenerative braking force, and the reduction in the deceleration feeling associated with the decrease in the negative pressure in the engine combustion chamber 14 can be compensated. Can be relaxed.

  In the example described above, the throttle valve 35 is controlled so as to increase the throttle opening THA and the negative pressure reduction processing is executed. Instead of this, or in addition to this, the variable valve mechanism of the intake valve 33 The negative pressure generated in the engine combustion chamber 14 may be reduced by increasing the maximum lift amount by 51.

  In each of the above modifications, the negative pressure reduction process is executed by adjusting the throttle opening THA and the maximum lift amount of the intake valve 33. Instead of or in addition to this, the following is performed. A simple configuration can also be adopted. That is, a valve timing variable mechanism that can change the valve timing of at least one of the intake valve 33 and the exhaust valve 34 is further provided. The valve overlap amount is increased by changing the valve timing by the variable valve timing mechanism. Further, the negative pressure generated in the engine combustion chamber 14 can be reduced by increasing the exhaust gas (internal EGR gas) blown back to the engine combustion chamber 14 from the exhaust passage 32. In this case, the variable valve timing mechanism may be provided separately from the variable valve mechanisms 51 and 52, or the variable valve mechanisms 51 and 52 may have a function of changing the valve overlap amount. Good.

  In each of the above modifications, the negative pressure reduction process is executed by adjusting the throttle opening THA, the maximum lift amount of the intake valve 33, and the valve overlap amount. However, instead of or in addition to this, Thus, by increasing the opening degree of the EGR valve 42, exhaust (external EGR gas) introduced into the engine combustion chamber 14 from the exhaust passage 32 via the intake passage 31 is increased, and is generated in the engine combustion chamber 14. It is also possible to reduce the negative pressure.

  In the above embodiment, the warm-up promotion process is executed at a predetermined time period ΔT, and the current control is performed by integrating the duty ratio D of the pump 23 in each control period, that is, the flow rate q and the predetermined time ΔT. The flow rate Q of the cooling water flowing through the circulating water channel 20 is calculated from the cycle to the next control cycle, and the flow rate Q is sequentially integrated for each control cycle to calculate the discharge amount integrated value ΣQ of the pump 23. I tried to do it. On the other hand, if the warm-up promotion process is executed at a predetermined crank angle period Δα, in addition to this crank angle period Δα, a period from the current control period to the next control period based on the engine speed NE Then, the flow rate Q of the cooling water flowing through the circulation water channel 20 is calculated, and the flow rate Q is sequentially integrated for each control period, thereby calculating the discharge amount integrated value ΣQ of the pump 23.

The negative pressure reduction process may be performed only during the execution of the warm-up promotion process, and this process may not be performed after the warm-up promotion process is completed.
The target throttle opening THAt may be corrected based only on the correction amount α calculated based on the coolant temperature θ. Alternatively, the target throttle opening THAt may be corrected based only on the correction amount β calculated based on the elapsed time from the start of deceleration fuel cut processing. Or target throttle opening THAt can also be set to the fixed value which can reduce a negative pressure compared with the case where such a warming-up promotion process is not performed.

  In the above embodiment and each modified example, after the warm-up promotion process is completed, the period for performing the negative pressure reduction process is changed according to the flow rate of the cooling water, but a predetermined period has elapsed. Until this is done, negative pressure reduction processing may be executed.

  In the above-described example, the electric rotary pump 23 is employed to variably set the discharge amount. However, for example, an engine-driven pump that has been used in the past can also be employed. However, in this case, a mechanism capable of changing the discharge amount regardless of the rotational speed of the crankshaft 19 in the internal combustion engine 10 is separately provided. For example, a pump is employed in which the rotation shaft is drivingly connected to the crankshaft 19 of the internal combustion engine 10 via a clutch, and the clutch is switched between a state in which cooling water is discharged and a state in which discharge is stopped by engaging / disengaging the clutch. You can also. In addition, if the power transmission from the crankshaft 19 of the internal combustion engine 10 can be connected and disconnected, for example, a pulley (not shown) attached to the rotation shaft of the pump is driven with respect to a belt that travels with the rotation of the output shaft. You may make it perform this with other connection / disconnection mechanisms, such as connecting / disconnecting power transmission by pressing / separating.

  -In each embodiment including the modification mentioned above, although the process which stops the driving | operation of the pump 23 and stops the circulation of the cooling water in the circulation channel 20 was illustrated as a warming-up promotion process, the warming-up promotion process in this invention is illustrated. Although the pump 23 is operated, for example, a minimum amount of cooling water that does not cause local boiling of cooling water in the water jacket 13 is circulated through the circulation channel 20, and the discharge amount is limited to a predetermined amount or less. Is also included.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Cylinder block, 12 ... Cylinder head, 13 ... Water jacket, 14 ... Engine combustion chamber, 15 ... Cylinder bore, 16 ... Fuel injection valve, 17 ... Piston, 17a ... Piston ring, 17b ... Expander, 17c ... Ring groove, 18 ... Oil pan, 19 ... Crankshaft, 20 ... Circulating water passage, 21 ... Detour passage, 22 ... Radiator passage, 23 ... Pump, 24 ... Thermostat, 25 ... Radiator, 31 ... Intake passage, 32 ... Exhaust Passage, 33 ... intake valve, 34 ... exhaust valve, 35 ... throttle valve, 40 ... EGR device, 41 ... EGR passage, 42 ... EGR valve, 51 ... variable valve mechanism (lift amount changing mechanism, valve timing changing mechanism), 52 ... Variable valve mechanism (lift amount changing mechanism, valve timing changing mechanism), 61 ... Power component Mechanism 62 ... Motor generator 63 ... Power control device 64 ... Battery 65 ... Deceleration mechanism 91 ... Control device (negative pressure variable means, control means) 92 ... Water temperature sensor 93 ... Crank angle sensor 94 ... Accelerator sensor.

Claims (10)

A warm-up system that includes a sensor that detects the temperature of the cooling water around the cylinder bore, and that restricts the pump discharge rate to the circulation channel at least as an execution condition that the detected temperature of the cooling water is less than a predetermined upper limit temperature. In a control device for an on-vehicle internal combustion engine provided with a cooling device that controls the pump to execute an acceleration process,
Negative pressure variable means capable of changing the negative pressure of the engine combustion chamber in the intake stroke;
Control means for controlling the negative pressure variable means so that the negative pressure is reduced when the fuel cut during deceleration is performed during the warm-up promotion process compared to when the warm-up promotion process is not executed. And a control device for an on-vehicle internal combustion engine. 2. The on-vehicle internal combustion engine according to claim 1, wherein the control unit sets a reduction amount when the negative pressure is reduced to a larger value when the temperature of the cooling water around the cylinder bore is high than when the temperature is low. Control device. 3. The control unit according to claim 1, wherein when the elapsed time after the fuel cut at the time of deceleration is short, the amount of decrease when the negative pressure is decreased is set to a larger value than when it is long. In-vehicle internal combustion engine control device. The negative pressure variable means includes a throttle valve that is provided in the intake passage and adjusts the intake air amount,
The control device for an on-vehicle internal combustion engine according to any one of claims 1 to 3, wherein the control means decreases the negative pressure by increasing an opening of the throttle valve. The negative pressure variable means includes a lift amount changing mechanism capable of changing the lift amount of the intake valve,
The on-board internal combustion engine control device according to any one of claims 1 to 4, wherein the control means decreases the negative pressure by increasing a lift amount of the intake valve. The negative pressure variable means includes a valve timing changing mechanism that changes the valve timing of at least one of the intake valve and the exhaust valve,
The on-board internal combustion engine control device according to any one of claims 1 to 5, wherein the control means decreases the negative pressure by increasing a valve overlap amount through a change in the valve timing. The negative pressure varying means includes an EGR device comprising a communication passage communicating the exhaust passage and the intake passage and a metering valve for metering exhaust gas returned from the exhaust passage to the intake passage through the communication passage,
The said control means decreases the said negative pressure by increasing the opening degree of the said metering valve, and increasing the quantity of the exhaust_gas | exhaustion returned to the said intake passage from the said exhaust passage. The control apparatus of the vehicle-mounted internal combustion engine of description. The control means is configured to change the negative pressure so that the negative pressure is reduced as compared with a case where the warm-up promotion process is not executed until a predetermined period elapses after the warm-up promotion process ends. The on-vehicle internal combustion engine control device according to any one of claims 1 to 7. The on-board internal combustion engine control device according to claim 8, wherein the control means sets, as the predetermined period, an engine from when the warm-up promotion processing is ended until the integrated discharge amount of the pump reaches a predetermined amount. In the control apparatus of the vehicle-mounted internal combustion engine according to any one of claims 1 to 9,
The vehicle on which the internal combustion engine is mounted is one that also includes a motor generator as its drive source,
The control means controls the in-vehicle internal combustion engine so that the regenerative braking force by the motor generator increases when the negative pressure variable means is controlled so that the negative pressure decreases. .

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