JP4096786B2 - Valve timing control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve timing control device for an internal combustion engine that variably controls a valve timing of an engine valve by changing a relative rotational phase between a cam for opening and closing the engine valve and an engine output shaft.
[0002]
[Prior art]
As is well known, a variable valve timing mechanism that varies the opening / closing timing of intake / exhaust valves that are engine valves, that is, the valve timing, has been put to practical use as a device mounted on an on-board internal combustion engine. As the variable valve timing mechanism, a mechanism that makes the relative rotational phase of the camshaft relative to the crankshaft, which is the engine output shaft, and, in turn, the relative rotational phase of the cam disposed on the camshaft variable is widely adopted. Has been.
[0003]
Conventionally, as a valve timing control device for an internal combustion engine with such a variable valve timing mechanism, a device has been proposed that retards the closing timing of the intake valve when starting or stopping the internal combustion engine until the compression stroke (patent). Reference 1). In this control device, the actual compression ratio is lowered through the delay of the intake valve closing timing, and the compression reaction force generated in accordance with the compression of the in-cylinder gas during the compression stroke is reduced. The engine vibration at the time of stop is suppressed.
[0004]
[Patent Document 1]
JP 2000-34913 A
[0005]
[Problems to be solved by the invention]
By the way, in addition to the compression reaction force, a cam reaction force when the engine valve is opened acts on the crankshaft of the internal combustion engine as a reaction force against the rotation. If the generation times of the compression reaction force and cam drive reaction force overlap each other, even if the compression reaction force and the cam drive reaction force are not so large, a large rotational reaction force acts on the crankshaft. When starting and stopping the internal combustion engine, the following inconvenience occurs.
[0006]
For example, when starting the engine, if the rotational reaction force increases, the torque required for the starter motor to rotate the crankshaft increases. Therefore, problems such as an increase in the size of the starter motor and an increase in power consumption occur.
[0007]
In addition, both when the engine is started and when it is stopped, the amount of fluctuation in the rotational reaction force increases and the fluctuation in the engine rotational speed increases due to the overlap between the generation timing of the compression reaction force and the generation timing of the cam drive reaction force. Increases engine vibration.
[0008]
If automatic stop / start control is performed to automatically stop and restart the internal combustion engine according to the traveling state of the vehicle, such as stopping or starting, the frequency of engine start and engine stop increases. The influence of the above inconvenience becomes more remarkable. In such a case, since the internal combustion engine is stopped and started regardless of the driver's will, the increase in engine vibration as described above gives the driver a greater sense of discomfort.
[0009]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a valve timing control device for an internal combustion engine that can more effectively reduce the rotational reaction force of the internal combustion engine when the internal combustion engine is started or stopped. Is to provide.
[0010]
[Means for Solving the Problems]
In the following, means for achieving the above-described object and its operational effects are described.
According to a first aspect of the present invention, there is provided a valve timing control device for an internal combustion engine that variably controls a valve timing of the engine valve by changing a relative rotational phase between a cam for opening and closing the engine valve and an engine output shaft. Determining means for determining whether or not the output of the electric motor that rotates the engine output shaft when the engine is started is reduced, and when the determination means determines that the output of the electric motor is in a reduced state When the internal combustion engine is started so that the amount of deviation between the phase at which the driving reaction force of the cam reaches a peak and the phase at which the compression reaction force of the internal combustion engine reaches a peak is larger than when not. The gist of the present invention is to provide a control means for controlling the valve timing.
[0011]
In the above configuration, when the output of the motor is in a reduced state, the amount of deviation between the phase at which the cam drive reaction force peaks and the phase at which the compression reaction force peaks is increased, and the engine is starting due to the overlap of both reaction forces. The increase in the peak of the rotational reaction force of the engine output shaft is reduced. As a result, the engine output shaft can be easily rotated even with an electric motor having a reduced output. Further, the peak of the rotational reaction force is reduced, so that fluctuations in the engine rotational speed during startup are suppressed, and engine vibration is also suppressed.
[0012]
Incidentally, by changing the valve timing to increase the amount of phase shift at which both reaction forces peak as described above, it may be a disadvantageous condition for the establishment of the first explosion. Even in such a case, in the above configuration, when the output of the motor is not reduced and the engine output shaft can be rotated satisfactorily despite the increase in the peak of the rotational reaction force due to the overlap of both reaction forces, It is possible to set a valve timing advantageous for establishment.
[0013]
According to a second aspect of the present invention, in the valve timing control device for an internal combustion engine according to the first aspect, the determination means performs the determination based on a state of charge of a battery that supplies power to the electric motor. The gist.
[0014]
With the above configuration, it is possible to easily and accurately determine a decrease in the output of the electric motor. According to a third aspect of the present invention, there is provided a valve timing control device for an internal combustion engine that variably controls a valve timing of the engine valve by changing a relative rotational phase between a cam for opening and closing the engine valve and an engine output shaft. A judging means for judging whether or not the rotational reaction force of the engine output shaft when starting the engine is in a large state, and when it is judged by the judging means that the rotational reaction force is in a large state; The valve timing when starting the internal combustion engine so that the amount of deviation between the phase at which the driving reaction force of the cam peaks and the phase at which the compression reaction force of the internal combustion engine peaks is larger than The gist of the invention is to provide a control means for controlling the above.
[0015]
In the above configuration, when the rotational reaction force of the engine output shaft due to the cam drive reaction force or the compression reaction force of the internal combustion engine is large, the phase at which the cam drive reaction force peaks and the compression reaction force peaks. The amount of phase shift is increased, and an increase in the rotational reaction force of the engine output shaft during start-up due to the overlap of both reaction forces is reduced. Therefore, an increase in torque required for rotation of the engine output shaft at the time of starting the engine is suppressed, and the engine can be started well. Further, the peak of the rotational reaction force is reduced, so that fluctuations in the engine rotational speed during startup are suppressed, and engine vibration is also suppressed.
[0016]
Incidentally, by changing the valve timing to increase the amount of phase shift at which both reaction forces peak as described above, it may be a disadvantageous condition for the establishment of the first explosion. Even in such a case, with the above configuration, the peak of the rotational reaction force of the engine output shaft is low in the first place, and if the engine output shaft can be rotated satisfactorily without shifting the phase at which both reaction forces peak, the initial explosion is established. An advantageous valve timing can be set.
[0017]
According to a fourth aspect of the present invention, in the valve timing control device for an internal combustion engine according to the third aspect, is the output of an electric motor that rotates the engine output shaft reduced when the internal combustion engine is started? A further judging means for judging whether or not, and when the further judging means judges that the output of the electric motor is not in a reduced state, a prohibiting means for prohibiting the control of the valve timing by the control means, It is the gist of further comprising.
[0018]
In the above configuration, the valve timing is not changed when the engine output shaft can be sufficiently rotated even when the output of the motor is not lowered and the rotational reaction force of the engine output shaft is large. become. Therefore, startability can be ensured more efficiently.
[0019]
According to a fifth aspect of the present invention, in the valve timing control device for an internal combustion engine according to the fourth aspect, the output is reduced based on a state of charge of a battery that supplies power to the electric motor. The gist of this is to determine whether or not it is in a state.
[0020]
With the above configuration, it is possible to easily and accurately determine a decrease in the output of the electric motor. According to a sixth aspect of the present invention, there is provided a valve timing control device for an internal combustion engine that variably controls a valve timing of the engine valve by changing a relative rotational phase between a cam for opening and closing the engine valve and an engine output shaft. A judging means for judging whether or not the rotational reaction force of the engine output shaft when stopping the engine is in a large state, and when it is judged by the judging means that the rotational reaction force is in a large state; The valve timing when the internal combustion engine is stopped so that the amount of deviation between the phase at which the driving reaction force of the cam peaks and the phase at which the compression reaction force of the internal combustion engine peaks is larger than The gist of the invention is to provide a control means for controlling the above.
[0021]
In the above configuration, when the rotational reaction force of the engine output shaft due to the cam drive reaction force or the compression reaction force of the internal combustion engine is large, the phase at which the cam drive reaction force peaks and the compression reaction force peaks. The amount of phase shift is increased, and an increase in the rotational reaction force of the engine output shaft during the stop operation due to the overlap of both reaction forces is reduced. Therefore, fluctuations in the engine rotational speed due to the rotational reaction force of the engine output shaft are suppressed, and engine vibration during the stop operation of the internal combustion engine is also suppressed.
[0022]
The invention according to claim 7 is the valve timing control device for an internal combustion engine according to any one of claims 3 to 6, wherein the determination means is in a state where the rotational reaction force is large based on an engine temperature state. The gist is to determine whether or not.
[0023]
The magnitude of the driving reaction force of the cam that becomes the rotational reaction force of the engine output shaft and the compression reaction force of the internal combustion engine have a correlation with the engine temperature state. Therefore, it is possible to easily and accurately determine whether or not the rotational reaction force is large based on the engine temperature state.
[0024]
The invention according to claim 8 is the valve timing control apparatus for an internal combustion engine according to any one of claims 1 to 7, wherein the internal combustion engine is automatically operated in accordance with a traveling state of a vehicle on which the internal combustion engine is mounted. The main point is to stop and restart automatically.
[0025]
For example, a vehicle that performs idle stop control that automatically stops the internal combustion engine temporarily when the vehicle stops, a hybrid vehicle that has two drive sources of the internal combustion engine and the electric motor, and switches the drive source according to the situation In the applied internal combustion engine, the internal combustion engine is stopped and started frequently. In such an internal combustion engine, since the internal combustion engine is automatically stopped and started regardless of the operation of the driver, engine vibration during stoppage or start-up makes it easier for the driver to feel uncomfortable. For this reason, the effects of the above-described configurations can be exhibited more remarkably.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, an in-vehicle internal combustion engine 10 to which the present embodiment is applied includes a variable valve timing mechanism (VVT) 11. A crankshaft 12 that is an engine output shaft of the internal combustion engine 10 is connected to a drive wheel of the vehicle through an automatic transmission 13. The crankshaft 12 is connected to a starter 14 that is an electric motor for starting the engine, if necessary.
[0027]
Further, the crankshaft 12 is drivingly connected to a belt transmission mechanism 16 via an electromagnetic clutch 15. The belt transmission mechanism 16 is provided with an auxiliary machine such as a compressor for an air conditioner or a water pump, and a generator motor 17 that functions as either a generator or an electric motor depending on the situation. The electromagnetic clutch 15 is configured such that the drive connection between the belt transmission mechanism 16 and the crankshaft 12 can be connected and disconnected as necessary. Incidentally, in the present embodiment, the generator motor 17 has a configuration corresponding to the motor that rotates the engine output shaft when the internal combustion engine is started.
[0028]
The starter 14 and the generator motor 17 are electrically connected to a battery 18. The battery 18 supplies electric power to the starter 14 and the generator motor 17 to cause them to function as an electric motor. The battery 18 is charged with electric power generated when the generator motor 17 is functioning as a generator.
[0029]
Various controls relating to the traveling of the vehicle are performed by the electronic control unit 20. The electronic control unit 20 includes a CPU for executing the various controls, a memory for storing information necessary for the control, an input port for inputting a signal from the outside, an output port for outputting a command signal to the outside, and the like. It is prepared for.
[0030]
Various sensors for detecting information necessary for vehicle control are connected to the input port of the electronic control unit 20. For example, detection signals from the NE sensor 21 that detects the engine speed, the vehicle speed sensor 22 that detects the vehicle speed, the water temperature sensor 23 that detects the cooling water temperature of the internal combustion engine 10, the battery sensor 24 that detects the charge amount of the battery 18, and the like. Is input to the electronic control unit 20 through the input port. An ignition switch 25 is also connected to this input port, and a signal (IG signal) for notifying the operation status of the ignition switch 25 by the driver is input to the electronic control unit 20.
[0031]
On the other hand, the output port of the electronic control unit 20 is connected to a variable valve timing mechanism 11 of the internal combustion engine 10, a drive circuit such as a spark plug, an injector, and a throttle valve, and a hydraulic control circuit of the automatic transmission 13. The electronic control unit 20 controls the operation state of the internal combustion engine 10 and the shift control of the automatic transmission 13 through these drive controls. The output port is also connected to a control circuit for the starter 14 and the generator motor 17, a drive circuit for the electromagnetic clutch 15, and the like. The operation of the starter 14, the generator motor 17 and the electromagnetic clutch 15 is also controlled by the electronic control unit 20. Has been.
[0032]
Next, the variable valve timing mechanism 11 employed in the internal combustion engine 10 will be described with reference to FIG. FIG. 2 shows a perspective sectional structure of the variable valve timing mechanism 11.
[0033]
As shown in the figure, the variable valve timing mechanism 11 is disposed at one end of an intake side camshaft 30 where a cam 30a for opening and closing an intake valve is disposed. In general, the variable valve timing mechanism 11 includes a vane rotor 31 and a housing 32. It is prepared for.
[0034]
A cam sprocket 33 is disposed at the end of the intake side camshaft 30 where the variable valve timing mechanism 11 is disposed so as to be rotatable relative to the intake side camshaft 30. The cam sprocket 33 is drivingly connected to the crankshaft 12 via a timing belt 33a. The housing 32 is fixed to the cam sprocket 33 so as to be integrally rotatable.
[0035]
A vane rotor 31 is disposed inside the housing 32 so as to be rotatable relative to the housing 32. The vane rotor 31 is fixed to the intake side camshaft 30 so as to be integrally rotatable. A plurality of vanes 34 are formed on the outer periphery of the vane rotor 31, and each vane 34 is accommodated in a recess 35 formed on the inner periphery of the housing 32 so as to be movable in the circumferential direction. Pressure chambers 36 and 37 defined by the outer peripheral surface of the vane rotor 31 and the inner peripheral surface of the housing 32 are formed on both sides of each vane 34 in the circumferential direction.
[0036]
Oil is fed into the pressure chambers 36 and 37 so that the oil pressure acts on the circumferential side surface of the vane 34. A power for rotating the vane rotor 31 relative to the housing 32 is generated according to the oil pressure difference between the pressure chambers 36 and 37.
[0037]
When the vane rotor 31 and the housing 32 rotate relative to each other, the relative rotational phase of the intake camshaft 30 with respect to the cam sprocket 33 is changed, and as a result, the relative rotational phase of the cam 30a that opens and closes the intake valve with respect to the crankshaft 12 is changed. Is done. Thus, the valve timing of the intake valve is changed based on the control of the oil pressure in both the pressure chambers 36 and 37.
[0038]
Control of the variable valve timing mechanism 11 configured as described above is performed as follows.
The electronic control unit 20 sets a target valve timing vtt that is a target value of the valve timing of the intake valve based on the engine operating state such as the engine rotation speed and the engine load. Here, the target valve timing vtt is defined as a reference angle “0”, which is the most retarded position of the change timing of the valve timing of the intake valve by the variable valve timing mechanism 11, and an advance amount [° CA] from the most retarded position. expressed.
[0039]
On the other hand, the electronic control unit 20 detects the actual valve timing of the intake valve based on, for example, the detected value of the rotation phase of the intake camshaft 30. Then, the electronic control unit 20 feedback-controls the oil pressure in the pressure chambers 36 and 37 so that the detected actual valve timing coincides with the target valve timing vtt. Thereby, the valve timing of the intake valve is adjusted to an optimal timing according to the engine operating state.
[0040]
On the other hand, in this vehicle, the electronic control unit 20 executes idle stop control that automatically stops and restarts the operation of the internal combustion engine 10 in accordance with the traveling state. Next, an outline of the idle stop control in this vehicle will be described with reference to FIG.
[0041]
When the ignition switch 25 is operated from the “OFF” position to the “ON” position by the driver and the electronic control device 20 is activated, the electronic control device 20 changes its control mode to “mode” indicating a normal engine stop state. Set to “0”. When the driver operates the ignition switch 25 to the “STA” position when the “mode 0” is set, the starter 14 is drivingly connected to the crankshaft 12, and the internal combustion engine 10 is started by the output of the starter 14. Done. When the startup is successfully completed, the control mode of the electronic control unit 20 is shifted to “mode 1” indicating a normal engine operating state.
[0042]
When “mode 1” is set, the belt transmission mechanism 16 is drivingly connected to the crankshaft 12 by the electromagnetic clutch 15, and the accessories are driven by the output of the internal combustion engine 10. The generator motor 17 also receives the output of the internal combustion engine 10 through the belt transmission mechanism 16. The generator motor 17 at this time functions as a generator, and the generated electric power is charged in the battery 18.
[0043]
When the ignition switch 25 is operated to the “OFF” position by the driver during the setting of “mode 1”, the electronic control unit 20 executes a normal engine stop process to stop the internal combustion engine 10 and The control mode is shifted to the “mode 0”.
[0044]
On the other hand, when the idle stop execution condition is satisfied during the setting of “mode 1”, the control mode of the electronic control unit 20 is shifted to “mode 2” in which engine stop processing for automatically stopping the internal combustion engine 10 is executed. . In the present embodiment, as the idle stop execution condition, for example, the establishment of the idle stop execution condition is determined when all of the following conditions (a1) to (a5) are satisfied.
(A1) The accelerator operation amount is “0”.
(A2) The vehicle speed is “0”. That is, the vehicle is stopped.
(A3) The brake pedal is depressed.
(A4) The cooling water temperature is equal to or higher than a predetermined temperature Ta.
(A5) The hydraulic oil temperature of the automatic transmission 13 is equal to or higher than a predetermined temperature.
(A6) The amount of charge of the battery 18 is equal to or greater than a predetermined value.
[0045]
When the control mode is thus shifted to “mode 2”, the electronic control unit 20 stops the fuel supply and stops the internal combustion engine 10. When it is confirmed that the internal combustion engine 10 is completely stopped, the control mode of the electronic control unit 20 is shifted to “mode 3” indicating an engine stop state due to idle stop.
[0046]
When “mode 3” is set, the drive connection between the crankshaft 12 and the belt transmission mechanism 16 by the electromagnetic clutch 15 is released. At the same time, the generator motor 17 is operated as an electric motor, and the auxiliary machine is driven by the output. Thereby, the driving of the auxiliary machine is maintained even when the internal combustion engine 10 is stopped due to the idle stop.
[0047]
When the engine restart execution condition is satisfied during the setting of “mode 3”, the control mode of the electronic control unit 20 is shifted to “mode 4” for executing a restart process for restarting the internal combustion engine 10. . In the present embodiment, as the restart execution condition, for example, the satisfaction of the engine restart execution condition is determined when any of the following conditions (b1) to (b4) is satisfied.
(B1) The brake pedal was released.
(B2) The accelerator operation amount is not “0”.
(B3) A shift operation from the P (parking) range or the N (neutral) range to another shift range was performed.
(B4) The amount of charge of the battery 18 has fallen below a predetermined value.
[0048]
Thus, when the control mode is shifted to “mode 4”, the crankshaft 12 is reconnected to the belt transmission mechanism 16 by the electromagnetic clutch 15. At the same time, the generator motor 17 is operated as an electric motor, and the internal combustion engine 10 is restarted by the output. When the restart of the internal combustion engine 10 is completed successfully, the control mode of the electronic control unit 20 is shifted to the “mode 1”.
[0049]
When a failure occurs in the restart of the internal combustion engine 10 in the “mode 4” due to a system abnormality or the like during the setting of the “mode 3”, the control mode of the electronic control device 20 is the “mode 0”. It is transferred to. In this case, the internal combustion engine 10 is restarted only by a direct operation of the driver, that is, it is not automatically restarted.
[0050]
In the internal combustion engine 10 of the present embodiment in which the idle stop control as described above is performed, when the internal combustion engine 10 is automatically stopped in the “mode 2”, the valve timing of the intake valve is set in the “mode 4”. The valve timing at the start for restarting the internal combustion engine 10 is set in advance. The starting valve timing is normally set as shown by a solid line in FIG. The normal starting valve timing is set such that an appropriate compression pressure can be obtained in the cylinder at the fuel ignition timing and the restart of the internal combustion engine 10 can be completed in a shorter time.
[0051]
On the other hand, in the figure, the transition of the driving reaction force of the cam when such normal starting valve timing is set is indicated by a solid line. The driving reaction force of the cam is a reaction force against the rotation of the crankshaft 12 generated in accordance with intake and exhaust valve opening operations by the cam. Further, the figure also shows the transition of the compression reaction force, which is the rotational reaction force of the crankshaft 12 accompanying the air compression in the cylinder in the compression stroke of each cylinder. As shown in the figure, in this internal combustion engine 10, the phase at which the driving reaction force of the cam accompanying the opening operation of the intake valve reaches a peak (maximum value) when the normal starting valve timing is set, The phase at which the compression reaction force reaches a peak is almost in agreement. Therefore, the driving reaction force and the compression reaction force of the cams overlap each other and a larger rotation reaction force acts on the crankshaft 12 at this time. That is, the peak of the rotational reaction force of the crankshaft 12 at the time of restart is increased.
[0052]
As a result, when the output of the generator motor 17 is reduced due to a decrease in the battery charge amount or when the compression reaction force or the cam drive reaction force is high, the crankshaft 12 is It may be difficult to rotate, and the internal combustion engine 10 may not be restarted, or the restart may require a longer time or more electric power.
[0053]
Therefore, in the present embodiment, when the state is as described above, as shown by the alternate long and short dash line in the figure, the phase at which the cam driving reaction force reaches the peak and the phase at which the compression reaction force reaches the peak are shifted, The valve timing at the start is changed. In the example of the figure, the valve timing of the intake valve is changed to the advance side with respect to the normal valve timing at the start. Thereby, the overlap of both reaction forces is eliminated, and the peak of the rotation reaction force of the rotating crankshaft 12 is reduced.
[0054]
In addition, since the magnitude of the driving reaction force and the compression reaction force of the cam has a correlation with the temperature state of the internal combustion engine 10 as described below, the magnitude of the reaction force is based on the cooling water temperature here. I try to estimate. Hereinafter, an estimation mode of such a driving reaction force and compression reaction force of the cam will be described.
[0055]
FIG. 5 shows the relationship between the coolant temperature and the peak value of the driving reaction force of the cam.
The driving reaction force of the cam varies depending on the viscosity of the lubricating oil provided to the camshaft bearing and the like. The viscosity of the lubricating oil increases as the temperature decreases, and the cam reaction force increases at low temperatures. On the other hand, even if the viscosity of the lubricating oil becomes too low, the lubrication state of the bearings and the like deteriorates, and the driving reaction force of the cam increases. Therefore, as shown in the figure, the driving reaction force of the cam becomes very high in the extremely low temperature range and decreases as the cooling water temperature becomes high. Then, the driving reaction force of the cam is changed so as to start increasing when the cooling water temperature rises more than a certain level.
[0056]
In the present embodiment, as described above, when the coolant temperature is lower than the predetermined temperature Ta, idle stop is not performed (condition (a4)), and restart is not performed. Further, when the cooling water temperature rises to the predetermined temperature Ta, the viscosity of the lubricating oil is sufficiently lowered and the driving reaction force of the cam is at a sufficiently acceptable level. Therefore, when restarting from an idle stop, only the high temperature region in which the cam drive torque increases due to a decrease in the viscosity of the lubricating oil becomes a problem.
[0057]
On the other hand, FIG. 6 shows the relationship between the cooling water temperature and the peak value of the compression reaction force. When the engine temperature increases, the air sucked into the cylinder thermally expands in the cylinder and increases the in-cylinder pressure, so that the compression reaction force increases as the cooling water temperature increases, as shown in FIG.
[0058]
Therefore, in this embodiment, when the coolant temperature is equal to or higher than the predetermined value Tb, it is determined that the cam drive reaction force and the compression reaction force are in a large state. When it is determined as such, when it is determined that the output of the generator motor 17 is further lowered, the valve timing at the start is changed as described above.
[0059]
On the other hand, in this embodiment, a decrease in the output of the generator motor 17 is determined based on the charge amount of the battery 18. That is, it is determined that the output of the generator motor 17 is in a reduced state when the amount of charge of the battery 18 is low and sufficient power cannot be supplied to the generator motor 17. .
[0060]
FIG. 7 shows a flowchart of the “rotational reaction force reduction process” of the present embodiment. This process is periodically executed by the electronic control unit 20 as a scheduled interrupt process.
[0061]
When this process is started, it is first determined in step S100 whether the engine stop process in the “mode 2” is being performed. Here, if the engine stop process is not in progress (NO), this process is temporarily terminated.
[0062]
On the other hand, if the engine stop process is in progress (YES), in step S110, it is determined whether or not the coolant temperature is higher than the predetermined value Tb, that is, rotation of the crankshaft 12 such as cam drive reaction force or compression reaction force. It is determined whether or not the reaction force is large. In the subsequent step S120, it is determined whether or not the battery charge is in a reduced state, that is, whether or not the output of the generator motor 17 is in a reduced state.
[0063]
If any of the above conditions does not apply (S110: NO, or S120: NO), in step S130, the target valve timing vtt of the intake valve is a normal value that provides the optimum starting time as described above. The valve timing VTBST at the start is set. Thereby, the valve timing of the intake valve at this time is set to the timing indicated by the solid line in FIG.
[0064]
On the other hand, when any of the above states is applicable (S110: YES and S120: YES), the value obtained by adding the starting valve timing correction amount dvt to the normal starting valve timing VTBST in step S140 is the target valve timing. Set to vtt. The starting valve timing correction amount dvt only shifts the phase at which the cam drive torque peaks and the phase at which the compression reaction force peaks until the peak of the rotational reaction force of the crankshaft 12 is sufficiently reduced. The advance angle correction amount of the target valve timing vtt with respect to the normal starting valve timing VTBST is set. Thereby, the valve timing of the intake valve at this time is set to the timing indicated by the one-dot chain line in FIG.
[0065]
In this embodiment, the process of step S110 corresponds to the process of the “determination unit” that determines whether or not the rotational reaction force of the crankshaft 12 that is the engine output shaft is large. Further, the process of step S120 corresponds to the process of the “determination unit” or the process of the “further determination unit” that determines whether or not the output of the motor is in a reduced state. Further, the processing of step S120 corresponds to the processing of the “prohibiting means” for prohibiting the control of the valve timing by the “control means”. Further, the process of step S140 corresponds to the process of the “control unit”.
[0066]
According to this embodiment described above, the following effects can be obtained.
(1) In this embodiment, when the charge amount of the battery 18 is low and the output of the generator motor 17 is in a reduced state, the phase difference in which the cam drive reaction force peaks and the phase in which the compression reaction force peaks The valve timing of the intake valve is changed so as to increase the amount. Therefore, an increase in the peak of the rotational reaction force of the crankshaft 12 due to the overlap of both reaction forces is suppressed. Therefore, when the output of the generator motor 17 decreases, the crankshaft 12 can be rotated more easily, and the restart reliability can be improved.
[0067]
(2) In this embodiment, when it is determined that the cam drive reaction force or the compression reaction force of the internal combustion engine is large based on the engine temperature state, the phase at which the cam drive reaction force peaks and the compression reaction force The valve timing of the intake valve is changed so as to increase the amount of phase shift at which becomes a peak. Therefore, an increase in the peak of the rotational reaction force of the crankshaft 12 due to the overlap of both reaction forces is suppressed, and the certainty of restart can be improved.
[0068]
(3) In this embodiment, only when it is determined that the output of the generator motor 17 is in a reduced state and the driving reaction force of the cam or the compression reaction force of the internal combustion engine is large, The valve timing of the intake valve is changed. Therefore, unnecessary change in the valve timing is suppressed, and the rotational reaction force can be reduced more efficiently.
[0069]
(4) Since the peak of the rotational reaction force of the crankshaft 12 during restart is reduced, the output performance required for the generator motor 17 can be reduced. This also makes it possible to reduce the size and weight of the generator motor 17.
[0070]
(5) Since the output of the generator motor 17 during restart can be further reduced, the power consumption can be suppressed.
(6) According to the present embodiment, fluctuations in the engine rotational speed are suppressed through the change in valve timing as described above, and engine vibration during restart can be reduced.
[0071]
(7) In the present embodiment, since the valve timing during restart is set while the engine is stopped prior to the restart, an appropriate valve timing can be set more reliably at the start of restart.
[0072]
(Another embodiment)
The embodiment described above may be implemented with the following modifications. In the above embodiment, the valve timing at the time of restart is set in advance while the engine is stopped, but such valve timing is set immediately before execution of the restart process or immediately after the start of the restart process. You may make it set.
[0073]
In the above embodiment, the amount of deviation between the phase at which the cam drive torque peaks and the phase at which the compression reaction force peaks is increased by changing the valve timing to the advance side. By changing the timing to the retard side, the same amount of deviation can be increased.
[0074]
In the above embodiment, the amount of deviation between the phase at which the cam drive torque peaks and the phase at which the compression reaction force peaks is increased by changing the valve timing of the intake valve. By changing the valve timing, it is possible to increase the same amount of deviation.
[0075]
-Learning control which evaluates the result of the above-mentioned rotation reaction force reduction processing, and updates the value of valve timing correction amount dvt at the time of starting at any time based on the evaluation can also be applied. That is, when the internal combustion engine 10 is restarted in a state where the valve timing is changed by the rotational reaction force reduction process, the output torque and power consumption of the generator motor 17 required for the rotation of the crankshaft 12, the engine The rising speed of the rotational speed and its fluctuation are detected. Then, from the detection result, it is evaluated whether the set start time valve timing correction amount dvt is an appropriate value, and the value is appropriately corrected. If such learning control is applied, overcorrection and undercorrection of the valve timing are suppressed, and the effect of the rotational reaction force suppression process such as improving the reliability of restarting the internal combustion engine 10 and shortening the restart time is more sure. You will be able to play.
[0076]
In the above embodiment, the cam drive reaction force and the compression reaction force are estimated based on the coolant temperature, but the same estimation can be applied to the lubricating oil supplied to the internal combustion engine 10 and the like of the automatic transmission 13. It can also be performed based on the temperature of the hydraulic oil or the time elapsed since the previous engine stop. In short, the same estimation can be performed by using a parameter reflecting the temperature state of the internal combustion engine 10. In particular, when restarting with the crankshaft 12 connected to the automatic transmission 13, the temperature of the hydraulic oil of the automatic transmission 13 greatly affects the rotational reaction force of the crankshaft 12. More appropriate estimation can be performed by considering the temperature of the oil.
[0077]
In the above embodiment, the presence / absence of a decrease in the output of the generator motor 17 is determined based on the amount of charge of the battery 18, but such determination may be performed based on other parameters. Note that the output reduction of the generator motor 17 occurs due to demagnetization of the core of the generator motor 17 due to deterioration with time or high temperature in addition to the decrease in the charge amount of the battery 18. Therefore, for example, based on the temperature state of the generator motor 17, it can be determined whether or not the output of the generator motor 17 has decreased.
[0078]
In the above embodiment, the starting valve timing correction amount dvt is a fixed value, but the value may be variably set according to the engine temperature state.
FIG. 8 shows an example of variable setting according to the cooling water temperature. In the setting example shown in the figure, the cooling water temperature exceeds the predetermined value Tb according to the relationship between the cooling water temperature shown in FIGS. 4 and 5, the driving reaction force of the cam, and the compression reaction force of the internal combustion engine 10. As the value increases, the valve timing correction amount dvt at the time of start is increased. That is, as the driving reaction force or compression reaction force of the cam increases, the phase at which they peak is shifted more greatly. As a result, the amount of change in the valve timing can be kept to a minimum while suppressing an increase in the rotational reaction force, and an increase in the restart time associated with the change in the valve timing can be suppressed.
[0079]
Further, the value of the starting valve timing correction amount dvt may be variably set according to the degree of decrease in the output of the generator motor 17.
FIG. 9 shows an example of variable setting according to the charge amount of the battery 18. In the example of the figure, the value of the starting valve timing correction amount dvt is increased as the charge amount of the battery 18 decreases from the predetermined value α. In this way, even if the output decreases, the increase in the rotational reaction force is suppressed as much as necessary, and the amount of change in the valve timing is kept to the minimum necessary, thereby preventing an increase in the restart time associated with the change in the valve timing. Can do.
[0080]
Further, the value of the starting valve timing correction amount dvt may be variably set according to the elapsed time from the start of restart.
FIG. 10 shows an example of such a setting. In the example shown in the figure, the value of the starting valve timing correction amount dvt is gradually decreased from the time t1 when a predetermined time has elapsed from the time t0 when the restart is started.
[0081]
At the start of starting, the generator motor 17 must rotate the crankshaft 12 only with its own output torque. However, once the crankshaft 12 starts to rotate, the inertial force associated with the rotation can be used. The output torque required for the rotation of the motor becomes small. Therefore, as in the above example, the rotation of the crankshaft 12 can be maintained even if the value of the starting valve timing correction amount dvt is decreased after the restart is started. By the way, when set in this way, the amount of change in the valve timing can be reduced before the first explosion of the internal combustion engine 10 is started. You can also do it.
[0082]
Further, the value of the valve timing correction amount dvt at the start may be variably set according to the engine speed after the start of restart.
FIG. 11 shows an example of such setting. In the example shown in the figure, the value of the starting valve timing correction amount dvt is reduced as the engine speed increases. Therefore, it is possible to obtain the same effect as when the variable setting is performed according to the elapsed time after the start of the start.
[0083]
Further, in the example of the figure, the value of the starting valve timing correction amount dvt is set to “0” before the engine rotational speed increases to the rotational speed at which the first explosion starts. Therefore, in this setting example, it is possible to suitably avoid the adverse effect that the change in the valve timing for reducing the rotational reaction force has on the establishment of the first explosion.
[0084]
In the above embodiment, the valve timing is changed to reduce the rotational reaction force by determining both the increase in the drive reaction force and compression reaction force of the cam and the decrease in the output of the generator motor 17. One of those judgments may be omitted. That is, either one of the process in step S110 and the process in step S120 in FIG. 6 may be omitted. Judging that the rotation of the crankshaft 12 at the time of restart has become difficult based only on the increase in the driving reaction force and compression reaction force of the cam or only on the decrease in the output of the generator motor 17. It is possible enough to do.
[0085]
In the above-described embodiment, the case where the rotational reaction force reduction process is applied when restarting the internal combustion engine 10 after the idle stop is performed is described. However, the same rotational reaction force reduction process is also performed at the time of normal engine start by the starter 14. May be applied. Even in this case, the same effects as those of the above embodiment can be obtained.
[0086]
-When the internal combustion engine 10 is stopped, if the rotational reaction force of the crankshaft 12 increases due to the overlap of the driving reaction force and the compression reaction force of the cam, the fluctuation of the engine rotational speed increases and the engine vibration Will increase. Such an increase in engine vibration may give a driver an uncomfortable feeling.
[0087]
Therefore, if the valve timing is changed as described above when the internal combustion engine 10 is stopped to reduce the rotational reaction force of the crankshaft 12, such an increase in engine vibration can be suppressed. However, in this case, since the decrease in the output of the generator motor 17 does not affect the engine vibration, it is determined only whether the cam drive reaction force or the compression reaction force is large, and the valve timing as described above is determined. Can be changed. The rotational reaction force reduction process related to the engine stop can be similarly applied to the automatic stop related to the idle stop in the “mode 2” and the normal engine stop based on the operation of the driver.
[0088]
FIG. 12 shows an example of the rotational reaction force reduction process related to the reduction of the rotational reaction force when the internal combustion engine 10 is stopped.
When the process shown in FIG. 11 is started, first, in step S200, it is determined whether or not the engine stop process is started, that is, whether or not the control mode is shifted from "mode 1" to "mode 2". Is done. If the engine stop process is not started (NO), the process is temporarily terminated.
[0089]
On the other hand, if the engine stop process is started (YES), it is determined in step S210 whether the coolant temperature is higher than the predetermined value Tb, that is, the cam drive reaction force and the compression reaction force are large. It is determined whether or not.
[0090]
If the coolant temperature is equal to or lower than the predetermined value Tb (S210: NO), in step S220, the normal valve timing VTBST at which the target valve timing vtt of the intake valve obtains the optimum starting time as described above is obtained. Set to Thus, the valve timing at the start of the next restart of the internal combustion engine 10 is set to a timing at which an optimum start time is obtained in advance.
[0091]
On the other hand, when it is determined that the coolant temperature exceeds the predetermined value Tb and the cam reaction force or compression reaction force is large (S210: YES), the cam drive reaction force peaks in step S230. The target valve timing vtt is set so as to avoid the phase in which the compression reaction force reaches a peak. Thereby, the peak of the rotational reaction force of the crankshaft 12 when the internal combustion engine 10 is stopped is reduced, and an increase in engine vibration is suppressed.
[0092]
The present invention can be similarly applied to an internal combustion engine that employs a variable valve timing mechanism of a type different from the variable valve timing mechanism 11 shown in FIG. In short, if the internal combustion engine has a mechanism for changing the valve timing of the engine valve that is opened and closed by the cam by changing the relative rotation phase of the cam with respect to the engine output shaft, the rotational reaction force is suppressed as described above. Processing can be applied.
[0093]
Even in a hybrid vehicle or the like that has two drive sources of an internal combustion engine and an electric motor and switches the drive source according to the situation, the internal combustion engine is automatically stopped and automatically started according to the switching of the drive source. The rotation reaction force reduction processing in the same manner as described above or in a mode similar to the above can also be applied to the stop and start of the internal combustion engine employed in such a hybrid vehicle. Even in that case, the same effect as that of the above embodiment or an effect equivalent thereto can be obtained.
[0094]
-Furthermore, with respect to the engine stop and engine start based on the operation of the driver etc. of the internal combustion engine in which the internal combustion engine is not automatically stopped / automatically started, the rotational reaction force reduction processing in the same manner as that described above or in a similar manner thereto Can be applied. Even in that case, the same effect as that of the above embodiment or an effect equivalent thereto can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of an embodiment of the present invention.
FIG. 2 is a perspective sectional view of a variable valve timing mechanism for an internal combustion engine applied to the embodiment.
FIG. 3 is a control mode diagram of idle stop control in the same embodiment.
FIG. 4 is a time chart showing an example of changes in valve lift amount, cam drive reaction force, and compression reaction force in the internal combustion engine to which the embodiment is applied.
FIG. 5 is a graph showing the relationship between the engine temperature state and the cam drive reaction force in the internal combustion engine to which the embodiment is applied.
FIG. 6 is a graph showing a relationship between an engine temperature state and a compression reaction force in the internal combustion engine to which the embodiment is applied.
FIG. 7 is a flowchart showing a processing procedure of a rotational reaction force reduction process applied to the embodiment.
FIG. 8 is a graph showing an example of a change in the setting mode of the starting valve timing correction amount according to the engine temperature state;
FIG. 9 is a graph showing an example of a change in the setting mode of the valve timing correction amount at start according to the degree of decrease in the motor output.
FIG. 10 is a graph showing an example of changing a setting mode of a valve timing correction amount at start according to an elapsed time from the start of start.
FIG. 11 is a graph showing an example of a change in the setting mode of the valve timing correction amount at start according to the engine speed.
FIG. 12 is a flowchart of a rotational reaction force reduction process for a modified example in which the present invention is applied to a rotational reaction force reduction during an engine stop operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Variable valve timing mechanism (VVT), 12 ... Crankshaft, 13 ... Automatic transmission, 14 ... Starter, 15 ... Electromagnetic clutch, 16 ... Belt transmission mechanism, 17 ... Generator motor, 18 ... Battery, DESCRIPTION OF SYMBOLS 20 ... Electronic control device, 21 ... Rotational speed sensor, 22 ... Vehicle speed sensor, 23 ... Water temperature sensor, 24 ... Battery sensor, 25 ... Ignition switch, 30 ... Intake side camshaft, 30a ... Cam, 31 ... Vane rotor, 32 ... Housing 33 ... Cam sprocket, 33a ... Timing belt, 34 ... Vane, 35 ... Recess, 36, 37 ... Pressure chamber.

Claims (8)

In a valve timing control device for an internal combustion engine that variably controls the valve timing of the engine valve by changing the relative rotational phase between a cam for opening and closing the engine valve and the engine output shaft,
Determining means for determining whether or not the output of the electric motor that rotates the engine output shaft when the internal combustion engine is started is in a reduced state;
When it is determined by the determining means that the output of the electric motor is in a reduced state, the phase at which the driving reaction force of the cam is peaked and the compression reaction force of the internal combustion engine is at a peak compared to when the output is not. A valve timing control device for an internal combustion engine, comprising: control means for controlling the valve timing when starting the internal combustion engine so that a deviation amount from the phase becomes larger. The valve timing control device for an internal combustion engine according to claim 1, wherein the determination unit performs the determination based on a state of charge of a battery that supplies electric power to the electric motor. In a valve timing control device for an internal combustion engine that variably controls the valve timing of the engine valve by changing the relative rotational phase between a cam for opening and closing the engine valve and the engine output shaft,
Determination means for determining whether or not the rotational reaction force of the engine output shaft when starting the internal combustion engine is large;
When the determination means determines that the rotational reaction force is in a large state, the phase at which the cam drive reaction force peaks and the compression reaction force of the internal combustion engine reach a peak compared to when the rotation reaction force is not. A valve timing control device for an internal combustion engine, comprising: control means for controlling the valve timing when starting the internal combustion engine so that a deviation amount from the phase becomes large. The valve timing control apparatus for an internal combustion engine according to claim 3,
Further determining means for determining whether or not the output of the electric motor that rotates the engine output shaft when the internal combustion engine is started is in a reduced state;
When the further determination means determines that the output of the electric motor is not in a reduced state, a prohibition means for prohibiting the control of the valve timing by the control means;
A valve timing control device for an internal combustion engine, further comprising: 5. The valve timing control device for an internal combustion engine according to claim 4, wherein the further determination unit determines whether or not the output is in a reduced state based on a state of charge of a battery that supplies electric power to the electric motor. In a valve timing control device for an internal combustion engine that variably controls the valve timing of the engine valve by changing the relative rotational phase between a cam for opening and closing the engine valve and the engine output shaft,
Determining means for determining whether or not the rotational reaction force of the engine output shaft when stopping the internal combustion engine is in a large state;
When the determination means determines that the rotational reaction force is in a large state, the phase at which the cam drive reaction force peaks and the compression reaction force of the internal combustion engine reach a peak compared to when the rotation reaction force is not. A valve timing control device for an internal combustion engine, comprising control means for controlling the valve timing when the internal combustion engine is stopped so that a deviation amount from the phase becomes large. The valve timing control device for an internal combustion engine according to any one of claims 3 to 6, wherein the determination means determines whether or not the rotational reaction force is in a large state based on an engine temperature state. The valve timing control device for an internal combustion engine according to any one of claims 1 to 7, wherein the internal combustion engine is automatically stopped and restarted in accordance with a traveling state of a vehicle on which the internal combustion engine is mounted.

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