JP5012973B2 - Valve timing control device for internal combustion engine - Google Patents

Description

  The present invention relates to a valve timing variable mechanism that variably sets the opening / closing timing of an engine valve that is opened and closed by the camshaft by changing the relative rotation phase of the camshaft with respect to the crankshaft, and to limit the relative rotation phase to the change range thereof. The present invention relates to a valve timing control device for an internal combustion engine having a lock mechanism that locks in phase.

  An internal combustion engine mounted on a vehicle such as an automobile is often provided with a variable valve timing mechanism for appropriately changing the opening / closing timing (valve timing) of the engine valve in order to improve the output or emission. ing.

  The variable valve timing mechanism includes, for example, a housing that is drivingly connected to a crankshaft of an internal combustion engine and a vane body that is drivingly connected to a camshaft, and the housing and the vane body are disposed so as to be rotatable relative to the camshaft. Has been. A vane extending in the radial direction is formed on the vane body. The inside of the housing is partitioned into an advance side pressure chamber and a retard side pressure chamber by the vanes. These pressure chambers are respectively supplied with regulated hydraulic oil. Then, the hydraulic pressure in each pressure chamber acts on the vane, whereby the relative rotational phase of the vane body with respect to the housing, in other words, the relative rotational phase of the camshaft with respect to the crankshaft is changed to the advance side or the retard side. Specifically, when the hydraulic oil is supplied to the advance side pressure chamber and the hydraulic oil is discharged from the retard side pressure chamber, the relative rotation phase is changed to the advance side. On the other hand, when the hydraulic oil is discharged from the advance side pressure chamber and the hydraulic oil is supplied to the retard side pressure chamber, the relative rotation phase is changed to the retard side. The valve timing of the internal combustion engine is changed by changing the relative rotation phase of the camshaft in this way.

  Further, as a valve timing control device, the relative rotational phase of the camshaft is set to a predetermined lock phase (advancing side limit phase [most advanced angle phase] or retarded side limit phase [most retarded angle phase] in the control range). ) And a lock mechanism that mechanically locks is known (for example, see Patent Document 1). With this lock mechanism, the valve timing of the internal combustion engine is maintained at an appropriate timing when starting the engine, where it is difficult to obtain a sufficiently high pressure as the hydraulic oil supply pressure because the rotation speed of the oil pump is low.

  For example, the lock mechanism includes a lock pin that can be projected and retracted in a receiving hole formed in the vane body, a recess (lock hole) into which the tip of the lock pin is inserted, and the lock pin facing the lock hole side. It is configured with a spring or the like that biases. The lock mechanism includes a pressure chamber for unlocking (unlocking pressure chamber). The lock release pressure chamber communicates with the advance side pressure chamber and the retard side pressure chamber, and a part of the hydraulic oil is supplied. When a biasing force having a magnitude corresponding to the hydraulic pressure (unlocking pressure) in the unlocking pressure chamber acts on the lock pin, the lock pin is biased to the side away from the lock hole.

  In this lock mechanism, the protruding and retracting state of the lock pin, that is, the locked state and the released state in which the lock pin is released is selectively switched according to the magnitude relationship between the urging force of the spring and the urging force based on the unlocking pressure.

  For example, when the engine operation is stopped by turning off the operation switch, the operation of the valve timing control device is continued and the advance side pressure chamber or the retard side is changed so that the relative rotation phase of the camshaft is changed to the lock phase. The oil pressure in the pressure chamber is increased. Thereby, after that, the relative rotation phase changes to become a lock phase. In this state, when the unlocking pressure is lowered to a predetermined pressure (locking pressure) or less due to a decrease in the supply pressure of the oil pump accompanying the engine stoppage, the urging force of the spring exceeds the urging force based on the unlocking pressure. become. As a result, the lock pin moves to the lock hole side by the urging force of the spring, and the tip portion thereof is inserted into the lock hole. As a result, the lock mechanism is locked and the relative rotation between the housing and the vane body is restricted.

  On the other hand, when the operation of the oil pump is resumed when the internal combustion engine is started, the hydraulic pressure of the hydraulic oil supplied from the oil pump to the advance side pressure chamber and the retard side pressure chamber gradually increases. Accordingly, when the unlocking pressure becomes higher than a predetermined pressure, the biasing force based on the unlocking pressure exceeds the biasing force of the spring. As a result, the lock pin moves away from the lock hole, and the tip end portion of the lock pin is detached from the lock hole. As a result, the lock mechanism is released, and the housing and the vane body can be rotated relative to each other. When the lock mechanism shifts from the locked state to the released state in this way and the supply pressure of the oil pump further increases thereafter, the valve timing is changed based on the hydraulic pressure adjustment of the retard side pressure chamber and the advance side pressure chamber. Will be done.

JP 2009-156217 A

  By the way, when shifting the lock mechanism from the unlocked state to the locked state, it is desirable that the time required for the transition (transition time) is short. In the apparatus described above, such a transition time is determined by the time required for the relative rotational phase of the camshaft to become the lock phase and the time required for the lock release pressure to fall below a predetermined pressure.

  Here, in the above-described apparatus, the hydraulic pressure in the advance side pressure chamber and the retard side pressure chamber is adjusted so as to change the relative rotation phase of the camshaft to the lock phase when the operation of the internal combustion engine is stopped. Therefore, at this time, one of the pressure chambers (specifically, the pressure chamber to which hydraulic oil is supplied when the relative rotation phase is changed to the side away from the lock phase) discharges the hydraulic oil, so that the hydraulic pressure decreases. However, since the hydraulic oil is supplied to the other (specifically, the pressure chamber to which the hydraulic oil is supplied when the relative rotation phase is changed to the side close to the lock phase), the hydraulic pressure is hardly lowered.

  Thus, in the device having a structure in which the hydraulic pressure of one of the advance side pressure chamber and the retard side pressure chamber is unlikely to decrease, the unlocking pressure is difficult to decrease, and this is one factor that hinders the shortening of the transition time. End up. The apparatus described above has room for improvement in this respect.

  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 quickly shift a lock mechanism to a locked state.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
According to a first aspect of the present invention, there is provided a variable valve timing mechanism for changing a relative rotational phase of a camshaft with respect to a crankshaft to a target phase based on hydraulic pressure supplied to an advance side pressure chamber and a retard side pressure chamber, A valve mechanism for an internal combustion engine comprising: a lock mechanism that locks the relative rotation phase at a limit phase of the change range when the oil pressure is low, and a release mechanism that releases the lock state when the oil pressure increases. A timing control device, wherein the relative rotation phase is set closer to the limit phase in a period from the start of a stop operation for stopping the operation of the internal combustion engine to the stop of rotation of the crankshaft. The adjustment of the hydraulic pressure in the first mode to be changed and the change in the relative rotation phase to the side away from the limit phase Further comprising execution means for executing in combination a hydraulic adjustment as its gist.

  In the above configuration, when the internal combustion engine is stopped, when the hydraulic pressure is adjusted in the first mode so as to change the relative rotation phase of the camshaft to the limit phase, it operates from one of the advance side pressure chamber and the retard side pressure chamber. By performing the hydraulic pressure adjustment in the second mode in which the relative rotation phase is changed to the side away from the limit phase while the oil is discharged and the hydraulic pressure decreases, the advance side pressure chamber and the retard angle are changed. The hydraulic oil is also discharged from the other side pressure chamber, and the hydraulic pressure is lowered.

  Thus, according to the above configuration, the hydraulic pressure in the advance side pressure chamber and the hydraulic pressure in the retard side pressure chamber can be reduced separately by adjusting the hydraulic pressure in the first mode and the second mode, respectively. As a result, the hydraulic pressure in the advance side pressure chamber and the retard side pressure chamber, and thus the unlocking pressure, can be quickly reduced, and the lock mechanism can be quickly shifted from the released state to the locked state. .

  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 execution means adjusts the hydraulic pressure in the first mode until the relative rotational phase reaches the limit phase. The gist is that the hydraulic pressure adjustment in the second mode is executed when the relative rotational phase reaches the limit phase.

  In the above configuration, when the operation of the internal combustion engine is stopped, first, the hydraulic pressure adjustment in the first mode is executed, and the relative rotation phase of the camshaft is changed to the limit phase. At this time, the hydraulic oil is discharged from one of the advance side pressure chamber and the retard side pressure chamber (specifically, the pressure chamber to which the hydraulic oil is supplied when the relative rotational phase is changed away from the limit phase). As a result, the hydraulic pressure decreases. Then, when the relative rotational phase of the camshaft reaches the limit phase thereafter, the hydraulic pressure adjustment in the second mode is executed. At this time, since the hydraulic pressure of the advance side pressure chamber and the retard side pressure chamber has already been lowered by the hydraulic pressure adjustment in the first mode prior to this, the relative rotational phase of the camshaft is separated from the limit phase. In addition, the operating oil is discharged from the other of the advance side pressure chamber and the retard side pressure chamber, and the hydraulic pressure is lowered.

  Thus, according to the above configuration, the hydraulic pressure of one of the advance side pressure chamber and the retard side pressure chamber is reduced in accordance with the change of the relative rotational phase of the camshaft to the limit phase, and the relative rotational phase is The hydraulic pressure of each pressure chamber can be suitably reduced such that the other hydraulic pressure of the advance side pressure chamber and the retard side pressure chamber is reduced while suppressing the change of the relative rotational phase after reaching the limit phase. .

  According to a third aspect of the present invention, in the valve timing control device for an internal combustion engine according to the first aspect, the execution means starts executing the hydraulic pressure adjustment in the second mode as the stop operation starts. When the relative rotational phase changes to a phase on the side away from the limit phase, the hydraulic pressure adjustment in the second mode is temporarily suspended and the hydraulic pressure adjustment in the first mode is executed. Is the gist.

  According to the above configuration, in a situation where the relative rotational phase of the camshaft does not change to the phase away from the limit phase, the hydraulic pressure is adjusted in the second mode to adjust one of the advance side pressure chamber and the retard side pressure chamber. When the hydraulic pressure is lowered and the hydraulic pressure adjustment in the second mode is executed, in the situation where the relative rotation phase changes to the phase on the side away from the limit phase, the hydraulic pressure is adjusted in the first mode and the advance side The hydraulic pressure of the advance side pressure chamber and the hydraulic pressure of the retard side pressure chamber can each be reduced such that the other hydraulic pressure of the pressure chamber and the retard side pressure chamber is reduced.

  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, the execution means is configured so that the relative rotational phase is determined from the limit phase when the hydraulic pressure adjustment is performed in the second aspect. When the state that does not change to the phase on the separating side continues for a predetermined period, the hydraulic pressure adjustment in the second mode is interrupted and the hydraulic pressure adjustment in the first mode is executed over the predetermined period thereafter. Is the gist.

  One of the advance-side pressure chamber and the retard-side pressure chamber (specifically, the pressure chamber to which hydraulic oil is supplied when the relative rotational phase is changed to the side away from the limit phase through the hydraulic pressure adjustment in the first mode. ) Is low enough not to change the relative rotational phase of the camshaft to the phase away from the limit phase, but is not low enough to lock the locking mechanism. There is a case.

  In this regard, according to the above configuration, after the hydraulic pressure of one of the advance side pressure chamber and the retard side pressure chamber becomes low enough not to change the relative rotational phase to a phase separated from the limit phase, By alternately executing the hydraulic pressure adjustment in the first mode and the hydraulic pressure adjustment in the second mode, both the hydraulic pressure in the advance side pressure chamber and the hydraulic pressure in the retard side pressure chamber can be sufficiently reduced. Become.

  In the invention according to any one of claims 1 to 4, as in claim 5, the limit phase is a retarded limit phase with respect to the relative rotational phase, and the first mode is advanced. This is an adjustment mode in which the hydraulic oil is discharged from the angle side pressure chamber and the hydraulic oil is supplied to the retard side pressure chamber. The second mode is a mode in which the hydraulic oil is supplied to the advance side pressure chamber and the retard side. The present invention can be applied to an apparatus that is an adjustment mode in which hydraulic oil is discharged from a pressure chamber.

  According to a sixth aspect of the present invention, in the valve timing control device for an internal combustion engine according to any one of the first to fifth aspects, the stop operation is performed by operating a drive switch to stop the operation of the internal combustion engine. The gist is that it is a stop operation associated with the event.

  According to the above configuration, after the operation switch is operated to stop the operation of the internal combustion engine, in order to complete the transition from the unlocked state to the locked state early, the advance side pressure chamber and the retard side The oil pressure in the pressure chamber can be quickly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows schematic structure of the valve timing control apparatus concerning 1st Embodiment which actualized this invention. FIG. 3 is a cross-sectional view showing a cross-sectional structure of the locking mechanism according to the first embodiment. Sectional drawing which shows the cross-section of the locking mechanism. The flowchart which shows the execution procedure of the engine stop time control process concerning 1st Embodiment. The timing chart which shows an example of the execution aspect of the control processing at the time of the engine stop. The flowchart which shows the execution procedure of the engine stop time control processing concerning 2nd Embodiment which actualized this invention. The flowchart which shows the execution procedure of the control processing at the time of the engine stop. The timing chart which shows an example of the execution aspect of the control processing at the time of the engine stop.

(First embodiment)
Hereinafter, a first embodiment in which a valve timing control device according to the present invention is embodied will be described.

FIG. 1 shows a structure of a variable valve timing mechanism according to the valve timing control apparatus of the present embodiment and a hydraulic circuit structure of the control apparatus.
As shown in FIG. 1, the variable valve timing mechanism 10 includes a substantially ring-shaped housing 12 and a vane body 14 accommodated therein. The vane body 14 is connected to a camshaft 16 that drives an intake valve (not shown) of the internal combustion engine so as to be integrally rotatable. The housing 12 is connected to a cam pulley 18 that rotates in synchronization with a crankshaft (not shown) of the internal combustion engine so as to be integrally rotatable. The camshaft 16 rotates in the clockwise direction in FIG.

  A plurality of vanes 20 extending in the radial direction (specifically, the direction intersecting with the rotation axis) are formed on the outer periphery of the vane body 14. A plurality of groove portions 22 extending in the circumferential direction are formed on the inner periphery of the housing 12, and the vanes 20 are respectively disposed in the groove portions 22. Each groove portion 22 is partitioned by the vane 20 to form an advance side pressure chamber 24 and a retard side pressure chamber 26, respectively. In addition, in FIG. 1, although the vane 20 and the groove part 22 are each shown two each, the number can be changed suitably.

  The advance side pressure chamber 24 and the retard side pressure chamber 26 are connected to a hydraulic control valve 28 via appropriate oil passages. The hydraulic control valve 28 is supplied with hydraulic oil sent from an engine-driven oil pump 30 that is drivingly connected to the crankshaft. As the hydraulic control valve 28, a valve capable of adjusting the amount of hydraulic oil supplied to the advance side pressure chamber 24 or the retard side pressure chamber 26 according to the duty ratio of the applied voltage is adopted. Yes. The hydraulic control valve 28 operates based on the duty ratio of the drive signal input from the electronic control device 32 to supply hydraulic oil into the advance side pressure chamber 24 or the retard side pressure chamber 26, or advance angle. The pressure is discharged from the side pressure chamber 24 and the retard side pressure chamber 26. The vane 20 has a relative rotation phase in the groove portion 22 due to a difference in hydraulic oil pressure (hydraulic pressure) between the advance side pressure chamber 24 and the retard side pressure chamber 26 formed on both side surfaces thereof. Is set to the desired phase. As a result, the vane body 14 is rotated relative to the housing 12, and the relative rotation phase of the camshaft 16 with respect to the cam pulley 18 is changed, so that the opening / closing timing (valve timing) of the intake valve is changed.

  The duty ratio of the drive signal is adjusted in the range of “0% to 100%”, and each pressure is adjusted so that the relative rotation phase is quickly changed to the advance side as the duty ratio approaches “100%”. The oil pressure in the chambers 24 and 26 is adjusted. Further, the hydraulic pressures of the pressure chambers 24 and 26 are adjusted so that the relative rotation phase is quickly changed to the retard side as the duty ratio approaches “0%”.

Specifically, such valve timing control is performed as follows.
The electronic control unit 32 receives parameters representing the engine operating state such as the rotational phase of the camshaft 16 detected by the cam angle sensor, the rotational phase of the crankshaft detected by the crank angle sensor, and the engine rotational speed NE. The

  The electronic control unit 32 calculates an appropriate valve timing according to the engine operating state based on these parameters, and calculates a target phase of the relative rotational phase of the camshaft 16 according to the calculated valve timing. Further, the current relative rotational phase of the camshaft 16 is calculated from the relationship between the rotational phase of the crankshaft and the rotational phase of the camshaft 16.

  When the target phase is different from the current phase, the electronic control unit 32 discharges the hydraulic oil from one of the advance side pressure chamber 24 and the retard side pressure chamber 26 and supplies the hydraulic oil to the other side. The operation of the hydraulic control valve 28 is controlled so as to supply. Specifically, when the current relative rotation phase is a phase retarded from the target phase, hydraulic oil is supplied to the advance side pressure chamber 24 in order to change the relative rotation phase to the advance side. The operation of the hydraulic control valve 28 is controlled so that the hydraulic oil is discharged from the retard side pressure chamber 26. In the present embodiment, such a hydraulic pressure adjustment mode functions as a second mode in which the relative rotational phase is changed to a side away from the limit phase. On the other hand, when the current relative rotational phase is a phase advanced from the target phase, the hydraulic oil is discharged from the advanced pressure chamber 24 and the retarded side to change the relative rotational phase to the retarded side. The operation of the hydraulic control valve 28 is controlled so that the hydraulic oil is supplied to the pressure chamber 26. In the present embodiment, this hydraulic pressure adjustment mode functions as a first mode for changing the relative rotational phase to a side closer to the limit phase. Then, the vane body 14 rotates relative to the housing 12 in accordance with the hydraulic pressure difference between the advance side pressure chamber 24 and the retard side pressure chamber 26 generated by executing the operation control of the hydraulic control valve 28. Valve timing is adjusted.

  As a result of adjusting the hydraulic pressures of the pressure chambers 24 and 26 as described above, when the target phase matches the current relative rotational phase, the electronic control unit 32 operates the hydraulic oil for the advance side pressure chamber 24 and the retard side pressure chamber 26. The operation of the hydraulic control valve 28 is controlled so as to stop the supply and discharge. As a result, the pressures in the advance-side pressure chamber 24 and the retard-side pressure chamber 26 are held substantially evenly, and the relative rotation phase of the vane body 14 is maintained.

  In the variable valve timing mechanism 10, the vane body 14 is relatively movable in a range (change range) from a phase in which the vane 20 abuts on one side wall of the groove 22 to a phase in which the vane 20 abuts on the opposite side wall of the groove 22. It can be turned. In the following, the relative rotational phase of the camshaft 16 when the vane body 14 is relatively rotated to the most retarded side (rear side in the rotational direction of the camshaft 16), that is, the control limit phase on the retarded side of the above-described change range. This is called “most retarded phase”. This phase is set as an initial position when the hydraulic control valve 28 is not controlled by the electronic control device 32, that is, a position when the engine is stopped. On the other hand, the relative rotational phase of the camshaft 16 when it is relatively rotated to the most advanced side (the front side in the rotational direction of the camshaft 16), that is, the control limit phase on the advanced side of the change range is referred to as the "most advanced phase". That's it.

  As described above, in the valve timing control device according to the present embodiment, the relative rotation phase of the camshaft 16 is adjusted by adjusting the hydraulic pressure in the advance side pressure chamber 24 and the retard side pressure chamber 26 through the operation control of the hydraulic control valve 28. Is appropriately changed in the range from the “most retarded phase” to the “most advanced angle phase”. The valve timing of the intake valve that is driven to open and close with the rotation of the camshaft 16 is made variable by changing the relative rotation phase of the camshaft 16.

  Further, the variable valve timing mechanism 10 of the present embodiment is provided with a lock mechanism 34 that restricts the relative rotation of the vane body 14 when the hydraulic pressure is low, such as when the engine is started. Hereinafter, the lock mechanism 34 will be described.

  A stepped accommodation hole 36 extending in parallel with the axial direction of the camshaft 16 is formed in one of the vanes 20. Inside the accommodation hole 36, a lock pin 38 is disposed so as to be able to appear and retract.

  As shown in FIGS. 2 and 3, the lock pin 38 extends from the position shown in FIG. 2 to the position shown in FIG. 3 with its outer peripheral surface slidingly in contact with the inner peripheral surface of the receiving hole 36. The camshaft 16 is moved in the axial direction. The lock pin 38 is urged toward the housing 12 by the coil spring 40. An enlarged stepped portion 38a is formed at the end of the lock pin 38, and an unlocking pressure chamber which is an annular space is formed between the stepped portion 38a and the stepped portion 36a of the receiving hole 36. 42 is formed. The unlocking pressure chamber 42 is connected to the retarding pressure chamber 26 through a retarding oil passage 44 formed in the vane 20 so that the pressure in the retarding pressure chamber 26 is transmitted. It has become.

  On the other hand, the housing 12 is formed with a lock hole 48 as a recess into which the lock pin 38 can be inserted when the relative rotation phase of the camshaft 16 (the relative rotation phase of the vane body 14) is the most retarded phase. ing. As shown in FIG. 2, when the tip end portion of the lock pin 38 is inserted into the lock hole 48 by the urging force of the coil spring 40, the vane body 14 is mechanically fastened to the housing 12 and its relative rotation is achieved. The movement is regulated (locked).

  A space defined by the lock hole 48 and the tip portion of the lock pin 38 is a lock release pressure chamber 50. The unlocking pressure chamber 50 is connected to the advance side pressure chamber 24 through the advance side oil passage 46 formed on the sliding contact surface between the vane 20 and the housing 12, so that the advance angle side pressure chamber 24. Pressure is transmitted.

  Both the hydraulic oil pressures in the unlocking pressure chambers 42 and 50 act in the direction in which the lock pin 38 is detached from the lock hole 48. Therefore, when the operation of the internal combustion engine is stopped, the relative rotation phase of the vane body 14 becomes the most retarded phase, and the pressure in the advance side pressure chamber 24 and the retard side pressure chamber 26 decreases in this state. When the pressure in the unlocking pressure chambers 42 and 50 becomes sufficiently low, the lock pin 38 is moved by the biasing force of the coil spring 40. As a result, as shown in FIG. 2, the distal end portion of the lock pin 38 is inserted into the lock hole 48, and the relative rotation of the vane body 14 is locked.

  The apparatus of the present embodiment includes an operation switch 52 that is operated when starting and stopping the internal combustion engine, a battery 54 for supplying power to various electrical components, a hydraulic control valve 28, and a battery for the electronic control unit 32. A relay 56 is provided for switching between a state in which power is supplied from 54 and a state in which the supply is stopped based on a command signal from the electronic control device 32.

  In the present embodiment, when the operation of the internal combustion engine is stopped by turning off the operation switch 52, the relay 56 is operated so that power supply to the hydraulic control valve 28 and the electronic control device 32 is continued for a predetermined period. The operation control of the hydraulic control valve 28 by the electronic control device 32 is continued. In the process of stopping the engine operation, basically, the operation control of the hydraulic control valve 28 is executed so that the relative rotation phase of the camshaft 16 becomes the most retarded phase. As a result, the lock mechanism 34 locks the camshaft 16 at the most retarded phase of the relative rotational phase.

  On the other hand, when the internal combustion engine is started by turning on the operation switch 52, the pressure in one or both of the advance side pressure chamber 24 and the retard side pressure chamber 26 increases, and the unlocking pressure chamber connected thereto. When the hydraulic pressures 42 and 50 are sufficiently increased, the lock pin 38 moves in a direction to be removed from the lock hole 48 as shown in FIG.

  As described above, in this embodiment, when the hydraulic pressure in each of the pressure chambers 24 and 26 is low, such as when the engine is stopped or immediately after the engine is started, the relative rotation of the vane body 14 is locked in the most retarded phase. Thus, when the oil pump 30 supplies a sufficient amount of hydraulic oil, the release of the relative rotation lock is released, and the valve timing control can be executed.

  In the present embodiment, when power is not supplied to the hydraulic control valve 28 or when a drive signal is not input, the operation state of the hydraulic control valve 28 is an operation that causes the oil pump 30 and the retard side pressure chamber 26 to communicate with each other. It becomes a state. Therefore, when the hydraulic control valve 28 is not operating at the time of starting the engine, hydraulic oil is supplied from the oil pump 30 toward the retarded pressure chamber 26, and at this time, the lock pin 38 is detached from the lock hole 48. It becomes possible to apply a preload. After that, by supplying hydraulic oil to the advance side pressure chamber 24 through the operation control of the hydraulic control valve 28, the hydraulic pressure is surely applied to the unlocking pressure chambers 42 and 50, and the pressure increase is surely performed. As a result, the lock by the lock mechanism 34 is reliably released.

  Here, in the valve timing control apparatus of the present embodiment, the lock mechanism 34 is shifted from the released state to the locked state when the operation of the internal combustion engine is stopped, but the time required for the shift (transition time) is short. Is desirable. This is due to the following reasons, for example.

  That is, as the transition time becomes shorter, the lock mechanism 34 can be shifted to the locked state even if the relative rotation phase of the camshaft 16 at the time of turning off the operation switch 52 is the advanced phase. The range of the relative rotation phase that can be controlled immediately before the operation switch 52 is turned off (usually during the idling operation) is widened. Therefore, it can be said that the shorter the transition time, the higher the degree of freedom in setting the control structure for the valve timing control. Further, as the transition time becomes shorter, the lock mechanism 34 can be shifted to the locked state sooner after the operation of the operation switch 52. Therefore, the shift to the hydraulic control valve 28 or the electronic control device 32 for the shift is enabled. The power supply can be stopped early.

  In the present embodiment, in order to shorten the transition time, in the period from the start of the stop operation for stopping the engine operation by the OFF operation of the operation switch 52 until the rotation of the crankshaft is stopped, The operation control of the control valve 28 is not executed simply so that the relative rotation phase of the camshaft 16 becomes the most retarded angle phase, but is executed as follows. That is, the operation control of the hydraulic control valve 28 in the first mode (specifically, the duty ratio of the drive signal is “0%”) in which the relative rotational phase of the camshaft 16 is changed to the side closer to the most retarded phase. And the operation control of the hydraulic control valve 28 in the second mode (“100%”) in which the relative rotational phase is changed away from the most retarded phase.

  Thus, when the operation of the hydraulic control valve 28 is controlled in the first mode when the operation of the internal combustion engine is stopped, the hydraulic oil is discharged from the advance side pressure chamber 24 and the hydraulic pressure in the advance side pressure chamber 24 is lowered. On the other hand, when the operation of the hydraulic control valve 28 is controlled in the second mode, the hydraulic oil is discharged from the retard side pressure chamber 26 and the hydraulic pressure in the retard side pressure chamber 26 is lowered.

  As described above, according to the present embodiment, by adjusting the hydraulic pressure through the operation control of the hydraulic control valve 28 in the first mode and the second mode, the hydraulic pressure of the advance side pressure chamber 24 and the retard side pressure chamber are controlled. The oil pressure of 26 is lowered separately. Therefore, compared with the device that simply controls the operation of the hydraulic control valve 28 in the first mode when the operation of the internal combustion engine is stopped, the hydraulic pressure (advance side unlocking pressure) and the retard side of the advance side pressure chamber 24 are compared. It becomes possible to quickly reduce the hydraulic pressure (retarding side unlocking pressure) of the pressure chamber 26, and the locking mechanism 34 shifts from the released state to the locked state at an early stage.

  Hereinafter, the details of the processing (control processing at the time of engine stop) relating to the operation control of the hydraulic control valve 28 when the engine operation is stopped will be described with reference to the flowchart shown in FIG. Note that the series of processing shown in this flowchart is interrupted every predetermined period on the condition that the predetermined time T1 elapses after the operation switch 52 is turned off to stop the operation of the internal combustion engine. This is a process executed by the electronic control device 32 as a process. In the present embodiment, this engine stop time control process functions as an execution means.

  As shown in FIG. 4, in this process, the duty ratio of the drive signal output to the hydraulic control valve 28 is “0” until the relative rotational phase of the camshaft 16 reaches the most retarded phase (step S101: NO). % "(Step S102). That is, at this time, the operation control of the hydraulic control valve 28 in the first mode is executed such that the hydraulic oil is discharged from the advance side pressure chamber 24 and the hydraulic oil is supplied to the retard side pressure chamber 26. Here, it is determined that “the relative rotation phase of the camshaft 16 has become the most retarded angle phase” when the difference between the actual relative rotation phase and the most retarded angle phase has become less than a predetermined value.

  Thereafter, when this process is repeatedly executed and the relative rotation phase of the camshaft 16 reaches the most retarded phase (step S101: YES), the duty ratio of the drive signal output to the hydraulic control valve 28 is “100%”. (Step S103). That is, at this time, the operation control of the hydraulic control valve 28 is executed in the second mode in which the hydraulic oil is supplied to the advance side pressure chamber 24 and the hydraulic oil is discharged from the retard side pressure chamber 26.

  Thereafter, the operation control of the hydraulic control valve 28 is continued until the duration of the operation control of the hydraulic control valve 28 when the duty ratio of the drive signal is “100%” reaches the predetermined time T2 (NO in step S104). And executed. The predetermined time T2 is based on the results of experiments and simulations. The hydraulic pressure in the retard side pressure chamber 26 (retard side lock release pressure) can be set to the predetermined pressure P1 (the lock mechanism 34 can be released). Sufficient time is obtained in advance and stored in the electronic control unit 32.

  When the duration of the operation control of the hydraulic control valve 28 with the drive signal duty ratio “100%” reaches the predetermined time T2 (step S104: YES), the power supply to the hydraulic control valve 28 is stopped. The operation is stopped (step S105).

Hereinafter, the effect by performing the engine stop time control process will be described with reference to FIG.
FIG. 5 shows an example of an execution mode of the engine stop time control process. In FIG. 5, [a] shows a mode of supplying electric power to the electronic control unit 32, [b] shows a transition of the engine rotational speed NE, [c] shows a transition of the relative rotational phase of the camshaft, [D] shows the transition of each unlocking pressure, and [e] shows the transition of the duty ratio of the drive signal.

  As shown in FIG. 5, when the operation switch 52 is turned off in order to stop the operation of the internal combustion engine at time t11, the electronic control unit continues until a predetermined time T1 elapses thereafter (time t11 to t16). The power supply to 32 is continued (FIG. [A]).

  Further, at this time, since the operation control of the internal combustion engine such as the fuel injection control and the ignition timing control is stopped, the engine speed NE ([b] in the same figure) decreases thereafter, and accordingly the oil pump 30 The supply pressure gradually decreases.

  Furthermore, the duty ratio ([e] in the figure) of the drive signal input to the hydraulic control valve 28 at this time is set to “0%”. As a result, the hydraulic pressure in the retard side pressure chamber 26 increases, and accordingly, the hydraulic pressure in the lock release pressure chamber 42 (retard side lock release pressure ([d] in the same figure)) increases, and the camshaft 16 The relative rotational phase ([c] in the figure) changes toward the most retarded phase. Further, at this time, the hydraulic pressure in the advance side pressure chamber 24 decreases, and accordingly, the hydraulic pressure in the unlock pressure chamber 50 (advance side unlock release pressure) also decreases. As described above, in the present embodiment, when the operation of the internal combustion engine is stopped, first, the relative rotation phase of the camshaft 16 is changed toward the most retarded angle phase, and the hydraulic pressure of the advance side pressure chamber 24 is adjusted in accordance with the change. Will fall.

Then, at the subsequent time t12, the advance side unlocking pressure falls below a predetermined pressure P2 (specifically, a pressure capable of shifting the locking mechanism 34 from the unlocked state to the locked state).
Furthermore, when the relative rotation phase of the camshaft 16 reaches the most retarded phase at time t13 thereafter, the duty ratio of the drive signal input to the hydraulic control valve 28 is switched to “100%”. As a result, the hydraulic pressure in the retard side pressure chamber 26 decreases, and accordingly, the hydraulic pressure in the lock release pressure chamber 42 (retard side lock release pressure) also decreases.

  At this time, since the hydraulic oil is supplied to the advance side pressure chamber 24, the relative rotational phase of the camshaft 16 may unnecessarily change to the advance side. However, the hydraulic pressure adjustment (advance side unlocking pressure) in the advance side pressure chamber 24 has already been sufficiently reduced by the hydraulic pressure adjustment (time t11 to t13) in the first mode prior to this, and the engine speed NE is increased. Since the supply pressure of the oil pump 30 is lowered and the hydraulic pressure in the advance side pressure chamber 24 is not so high. Therefore, at this time, the relative rotational phase of the camshaft 16 does not change to the advance side.

  Then, at the subsequent time t14, the retard side unlocking pressure falls below a predetermined pressure P1 (specifically, a hydraulic pressure capable of shifting the locking mechanism 34 from the unlocked state to the locked state). That is, at this time, since the advance side unlocking pressure falls below the predetermined pressure P2 and the retard side unlocking pressure falls below the predetermined pressure P1, the lock pin 38 is moved by the biasing force of the coil spring 40 (FIG. 2). The lock mechanism 34 is inserted into the lock hole 48 and the lock mechanism 34 is locked.

  As shown in FIG. 5, when the duration of the operation of the hydraulic control valve 28 with the duty ratio of the drive signal “100%” reaches a predetermined time T2 at a subsequent time t15, the power to the hydraulic control valve 28 is increased. Supply is stopped.

  Furthermore, when the elapsed time after the operation switch 52 is turned off reaches the predetermined time T1 at time t16, the power supply to the electronic control device 32 is stopped. Note that this predetermined time T1 is obtained in advance based on the results of experiments and simulations, and sufficient time is obtained in advance to shift the lock mechanism 34 from the unlocked state to the locked state through execution of the engine stop time control process. It is stored in the control device 32.

  Thus, in the engine stop time control process of the present embodiment, the hydraulic pressure adjustment in the first mode is executed until the relative rotation phase of the camshaft 16 reaches the most retarded angle phase, and the relative rotation phase is When the most retarded phase is reached, hydraulic pressure adjustment in the second mode is executed. For this reason, the hydraulic pressure of the advance side pressure chamber 24 is lowered in accordance with the change of the relative rotation phase of the camshaft 16 to the most retarded phase, and the relative rotation phase of the camshaft 16 becomes the most retarded phase. In this case, the hydraulic pressures of the pressure chambers 24 and 26 can be suitably reduced such that the hydraulic pressure of the retard side pressure chamber 26 is reduced while suppressing the change in the relative rotational phase. Therefore, when the operation of the internal combustion engine is stopped, it is possible to quickly reduce the hydraulic pressure in the advance side pressure chamber 24 and the retard side pressure chamber 26, and hence both the advance side unlock pressure and the retard side unlock pressure. Thus, the lock mechanism 34 can be shifted from the released state to the locked state at an early stage.

As described above, according to the present embodiment, the effects described below can be obtained.
(1) In a first mode in which the relative rotational phase of the camshaft 16 is changed to the side closer to the most retarded angle phase during a period from when the operation switch 52 is turned off until the engine rotational speed NE becomes “0”. The operation control of the hydraulic control valve 28 and the operation control of the hydraulic control valve 28 in the second mode in which the relative rotational phase is changed to the side away from the most retarded phase are executed together. Therefore, as compared with the device that simply controls the operation of the hydraulic control valve 28 in the first mode when the operation of the internal combustion engine is stopped, the hydraulic pressure in the advance side pressure chamber 24 and the retard side pressure chamber 26, and hence the advance side. The lock release pressure and the retard side lock release pressure can be quickly reduced, and the lock mechanism 34 can be shifted from the released state to the locked state at an early stage.

  (2) The hydraulic pressure adjustment of the advance side pressure chamber 24 and the retard side pressure chamber 26 is performed in the first mode until the relative rotational phase of the camshaft 16 reaches the most retarded phase, and the relative rotational phase is the maximum. When the retardation phase is reached, the second mode is used. For this reason, the hydraulic pressure of the advance side pressure chamber 24 is reduced in accordance with the change of the relative rotation phase of the camshaft 16 to the most retarded phase, and the relative rotation phase of the camshaft 16 becomes the most retarded phase. Can reduce the hydraulic pressure of each of the pressure chambers 24 and 26, such as reducing the hydraulic pressure of the retard side pressure chamber 26 while suppressing the change in the relative rotational phase.

  (3) After the operation switch 52 is operated to stop the operation of the internal combustion engine, in order to complete the transition from the unlocked state to the locked state of the lock mechanism 34 at an early stage, the advance side pressure chamber 24 and the retard side The hydraulic pressure in the pressure chamber 26 can be quickly reduced.

(Second Embodiment)
Hereinafter, a valve timing control device according to a second embodiment of the present invention will be described.

  The valve timing variable mechanism and lock mechanism to which the valve timing control device according to the present embodiment is applied, and the structure of peripheral devices thereof are the same as those shown in FIGS. 1 to 3, and the description thereof is omitted. To do. The valve timing control device according to the present embodiment and the valve timing control device according to the first embodiment differ only in the execution procedure of the engine stop time control process.

  Hereinafter, the execution procedure of the engine stop time control process according to the present embodiment will be described with reference to the flowcharts shown in FIGS. 6 and 7. Note that the series of processes shown in these flowcharts is interrupted every predetermined period on condition that the predetermined time T3 elapses after the operation switch 52 is turned off to stop the operation of the internal combustion engine. This is a process executed by the electronic control device 32 as a process. In the present embodiment, this engine stop time control process functions as an execution means.

  As shown in FIG. 6, in this process, first, when the operation switch 52 is turned off to stop the operation of the internal combustion engine (step S201: YES), the duty ratio of the drive signal output to the hydraulic control valve 28 is changed. It is set to “100%” (step S201). That is, when the operation switch 52 is turned off, first, hydraulic oil is supplied to the advance side pressure chamber 24 and discharged from the retard side pressure chamber 26. The execution of the operation control 28 is started.

Thereafter, under the condition that the following [Condition A] and [Condition B] are both satisfied (all of Steps S203 to S205 are “YES”), the hydraulic control valve 28 with the duty ratio of “100%” is used. The operation control is continued.
[Condition A] After the duty ratio is set to “100%”, the relative rotational phase of the camshaft 16 does not change to the advance side (step S204).
[Condition B] The duration of the state in which the duty ratio is set to “100%” is less than a predetermined time T4 (for example, several tens of milliseconds) (step S205).

  As a result of setting the duty ratio to “100%”, when the relative rotational phase of the camshaft 16 changes to the advance side and the above [Condition A] is not satisfied (step S204: NO), the duty ratio is “ It is switched to “0%” (step S206). In this case, the duration of the state in which the duty ratio is set to “0%” is a predetermined time T5 (for example, several tens of milliseconds) (step S201: NO, step S203: NO, In step S207: NO), the operation control of the hydraulic control valve 28 at the same duty ratio of “0%” is continued. Thereafter, this processing is repeatedly executed, and when the duration of the state in which the duty ratio is set to “0%” becomes equal to or longer than the predetermined time T5 (step S207: YES), the duty ratio is returned to “100%”. (Step S208).

  As described above, in this processing, when the relative rotation phase of the camshaft 16 is changed to the advance side by setting the duty ratio of the drive signal to “100%”, the duty ratio is once set to “0%”. After switching and continuing this for a predetermined time T2, a process of returning to “100%” is executed. That is, in this case, the operation control of the hydraulic control valve 28 in the second mode is temporarily interrupted, the hydraulic oil is discharged from the advance side pressure chamber 24, and the hydraulic oil is supplied to the retard side pressure chamber 26. The operation control of the hydraulic control valve 28 in the first mode such as supply is performed.

  If the relative rotation phase of the camshaft 16 does not change to the advance side even if the duty ratio of the drive signal is set to “100%” (step S201: NO, step S203: YES, step S204: YES). Then, it is determined whether or not the duration time in which the duty ratio is set to “100%” has reached a predetermined time T4 (step S205).

  When the duration of the state in which the duty ratio is set to “100%” is less than the predetermined time T4 (step S205: YES), the operation control of the hydraulic control valve 28 with the duty ratio being “100%”. Will continue. Thereafter, when the continuation time reaches the predetermined time T4 (step S205: NO), the duty ratio is switched to “0%” (step S206). The operation control of the hydraulic control valve 28 with the duty ratio being “0%” is performed until the duration time in which the duty ratio is set to “0%” reaches the predetermined time T5 (step S207: NO). When the continuation time is equal to or longer than the predetermined time T5 (step S207: YES), the duty ratio is returned to “100%” (step S208).

  Thus, in this process, even if the duty ratio of the drive signal is set to “100%”, if the relative rotation phase of the camshaft 16 does not change to the advance side, the duty ratio over the predetermined time T4 is “100%”. The operation control of the hydraulic control valve 28 at “” and the operation control of the hydraulic control valve 28 at the duty ratio “0%” over the predetermined time T5 are alternately executed repeatedly.

  Thereafter, as shown in FIG. 7, the operation control of the hydraulic control valve 28 continues until the elapsed time after the operation switch 52 is turned off reaches a predetermined time T6 (step S209: NO). Executed. The predetermined time T6 is based on the results of experiments and simulations, and the hydraulic pressure in the advance side pressure chamber 24 (advance side unlocking pressure) falls below the predetermined pressure P2 and the hydraulic pressure in the retard side pressure chamber 26. A sufficient time for the (retard side unlocking pressure) to fall below the predetermined pressure P <b> 1 is obtained in advance and stored in the electronic control device 32.

  When the elapsed time after the operation switch 52 is turned off reaches a predetermined time T3 (step S209: YES), the power supply to the hydraulic control valve 28 is stopped and the operation is stopped (step S210). . The predetermined time T3 is a time sufficient for shifting the lock mechanism 34 from the unlocked state to the locked state through the execution of the engine stop time control process according to the present embodiment based on the results of experiments and simulations. It is obtained in advance and stored in the electronic control unit 32.

Hereinafter, the effect by performing the engine stop time control process according to the present embodiment will be described with reference to FIG.
FIG. 8 shows an example of an execution mode of the engine stop time control process. In FIG. 8, [a] shows a mode of supplying electric power to the electronic control unit 32, [b] shows a transition of the engine rotational speed NE, [c] shows a transition of the relative rotational phase of the camshaft, [D] shows the transition of each unlocking pressure, and [e] shows the transition of the duty ratio of the drive signal.

  As shown in FIG. 8, when the operation switch 52 is operated to stop the operation of the internal combustion engine at time t21, the electronic control device 32 continues until a predetermined time T3 elapses thereafter (time t21 to t38). Is continued to be supplied ([a] in the figure).

  Further, since the operation control of the internal combustion engine such as the fuel injection control and the ignition timing control is stopped at time t21, the engine rotational speed NE ([b] in the same figure) decreases thereafter, and accordingly, the oil pump 30 The supply pressure gradually decreases.

  Furthermore, the duty ratio ([e] in the figure) of the drive signal input to the hydraulic control valve 28 at time t21 is set to “100%”. Therefore, thereafter, the hydraulic pressure in the retard side pressure chamber 26 decreases, and accordingly, the hydraulic pressure in the lock release pressure chamber 42 (retard side lock release pressure (FIG. [D])) also decreases. As described above, in the present embodiment, when the operation of the internal combustion engine is stopped, first, the hydraulic pressure in the retard side pressure chamber 26 and, consequently, the retard side unlocking pressure is reduced.

  Further, at time t21, the operating state of the hydraulic control valve 28 becomes a state in which hydraulic oil is supplied to the advance side pressure chamber 24, so that the relative rotational phase of the camshaft 16 ([c] in the figure) changes to the advance side. There is a risk. In this example, the relative rotational phase of the camshaft 16 has actually changed to the advance side (time t21 to t22).

  Therefore, the duty ratio of the drive signal is temporarily switched to “0%” at time t22, and the state is continued for a predetermined time T5 (time t22 to t23). Then, when the operation control of the hydraulic control valve 28 in the state where the duty ratio of the drive signal is “0%” is continued for a predetermined time T5, the duty ratio is returned to “100%” (time t23). As a result, the hydraulic pressure (retard side unlocking pressure) of the retard side pressure chamber 26 is lowered again thereafter.

  At time t23, the hydraulic pressure in the advance side pressure chamber 24 is lowered by the operation control of the hydraulic control valve 28 with the duty ratio of “0%” over the predetermined time T5 immediately before, and the engine rotational speed NE decreases. Accordingly, the supply pressure of the oil pump 30 is also lowered. Therefore, at this time, when the execution of the operation control of the hydraulic control valve 28 in the first mode is started, the rotational phase of the camshaft 16 does not change to the advance side. Therefore, at this time, when the operation control of the hydraulic control valve 28 with the duty ratio of “100%” is started, the operation continues for a predetermined time T4 thereafter (time t23 to t24).

  As described above, in the present process, the hydraulic control valve 28 in the first mode is operated in the period from the start of the stop operation for stopping the engine operation by the operation of turning off the operation switch 52 to the stop of the rotation of the crankshaft. The operation control and the operation control of the hydraulic control valve 28 in the second mode are executed together. Therefore, compared with the device that simply controls the operation of the hydraulic control valve 28 in the first mode when the operation of the internal combustion engine is stopped, the hydraulic pressure (advance side unlocking pressure) and the retard side of the advance side pressure chamber 24 are compared. It becomes possible to quickly reduce the hydraulic pressure (retarding side unlocking pressure) of the pressure chamber 26, and the locking mechanism 34 shifts from the released state to the locked state at an early stage.

  More specifically, in this process, when the relative rotational phase of the camshaft 16 does not change to the advance side, the operation control of the hydraulic control valve 28 in the second mode is executed, and the hydraulic pressure of the retard side pressure chamber 26 is increased. It begins to decline. Further, when the operation control of the hydraulic control valve 28 in the second mode is executed, the operation control of the hydraulic control valve 28 in the first mode is performed in a situation where the relative rotation phase of the camshaft 16 changes to the advance side. As a result, the hydraulic pressure in the advance side pressure chamber 24 decreases. As a result, the hydraulic pressure in the advance side pressure chamber 24 and the hydraulic pressure in the retard side pressure chamber 26 are reduced.

  At time t24, when the operation control of the hydraulic control valve 28 with the duty ratio of “100%” is continued for a predetermined time T4 without the relative rotational phase of the camshaft 16 changing to the advance side, the hydraulic pressure is thereafter increased. The operation control of the control valve 28 is executed as follows. That is, the operation control (time t24 to t26, t28 to t29,..., T34 to t35) of the hydraulic control valve 28 when the duty ratio over the predetermined time T5 is “0%” and the duty ratio over the predetermined time T4 are The operation control of the hydraulic control valve 28 at “100%” (time t26 to t28, t29 to t30,..., T35 to t36) is alternately and repeatedly executed. The hydraulic pressure in the advance side pressure chamber 24 (advance side unlocking pressure) becomes lower than the predetermined pressure P2 at time t25 in the execution process of the operation control of the hydraulic control valve 28, and at the retard side at time t27. The hydraulic pressure in the pressure chamber 26 (retarding side unlocking pressure) becomes lower than the predetermined pressure P1.

  Here, even when the hydraulic pressure in the advance side pressure chamber 24 is low enough not to change the relative rotation phase of the camshaft 16 to the advance side through the operation control of the hydraulic control valve 28 in the first mode. In some cases, the hydraulic pressure is not low enough to cause the lock mechanism 34 to shift to the locked state. In this case, if only the operation control of the hydraulic control valve 28 in the second mode is continuously executed, the hydraulic oil is supplied to the advance side pressure chamber 24, so that the advance angle is increased. There is a possibility that the time required until the hydraulic pressure in the side pressure chamber 24 is sufficiently lowered may be increased, and there is a possibility that the time required for shifting the lock mechanism 34 from the released state to the locked state may be increased.

  In this regard, in the present embodiment, after the hydraulic pressure in the advance side pressure chamber 24 is lowered to such an extent that the relative rotation phase of the camshaft 16 is not changed to the advance side, the hydraulic pressure in the first mode is set. The operation control of the control valve 28 and the operation control of the hydraulic control valve 28 in the second mode are executed alternately. Therefore, both the hydraulic pressure in the advance side pressure chamber 24 and the hydraulic pressure in the retard side pressure chamber 26 can be sufficiently reduced.

  Thereafter, at time t37, when the elapsed time after the operation switch 52 is turned off reaches a predetermined time T6, the power supply to the hydraulic control valve 28 is stopped. Furthermore, when the elapsed time after the operation switch 52 is turned off reaches the predetermined time T3 at time t38, the power supply to the electronic control device 32 is stopped.

As described above, according to the present embodiment, in addition to the effects described in (1) and (3) above, the effects described in (4) and (5) below can be obtained. .
(4) When the operation switch 52 is turned off, the execution of the operation control of the hydraulic control valve 28 in the second mode is started, and when the relative rotation phase of the camshaft 16 changes to the advance side, the second mode. The operation control of the hydraulic control valve 28 is temporarily interrupted to execute the operation control of the hydraulic control valve 28 in the first mode. Therefore, in a situation where the relative rotational phase of the camshaft 16 does not change to the advance side, it is possible to reduce the hydraulic pressure in the retard side pressure chamber 26 by executing the operation control of the hydraulic control valve 28 in the second mode. In addition, when the operation control of the hydraulic control valve 28 in the second mode is executed, the operation control of the hydraulic control valve 28 in the first mode is performed in a situation where the relative rotation phase of the camshaft 16 changes to the advance side. When executed, the hydraulic pressure of the advance side pressure chamber 24 can be reduced. Accordingly, the hydraulic pressure in the advance side pressure chamber 24 and the hydraulic pressure in the retard side pressure chamber 26 can be reduced.

  (5) After the hydraulic pressure in the advance side pressure chamber 24 becomes low enough not to change the relative rotation phase of the camshaft 16 to the advance side through the operation control of the hydraulic control valve 28 in the first mode, the first The operation control of the hydraulic control valve 28 in the aspect and the operation control of the hydraulic control valve 28 in the second aspect are alternately executed. Therefore, both the hydraulic pressure in the advance side pressure chamber 24 and the hydraulic pressure in the retard side pressure chamber 26 can be sufficiently reduced.

(Other embodiments)
Each of the above embodiments may be modified as follows.
In the first embodiment, the duty of the drive signal input to the hydraulic control valve 28 during the period from when the operation switch 52 is turned off until the relative rotation phase of the camshaft 16 reaches the most retarded phase. The ratio was set to “0%”. Instead, the target phase may be set to the most retarded phase in the period. Even with such a configuration, the operation control of the hydraulic control valve 28 can be executed in such a manner that the relative rotational phase of the camshaft 16 is changed to the side closer to the most retarded angle phase during the period.

  In the first embodiment, as a timing for switching the duty ratio of the drive signal to “100%” after the operation switch 52 is turned off, for example, after the relative rotational phase of the camshaft 16 becomes the most retarded phase. A timing slightly later than when the relative rotational phase becomes the most retarded phase may be set, for example, by setting a timing at which a predetermined time has elapsed. Further, as such timing, if the relative rotation phase of the camshaft 16 is surely changed to the most retarded angle phase due to pressing by the intake valve or the like, for example, the relative rotation phase is slightly different from the most retarded angle phase. It is also possible to set the timing before the relative rotational phase becomes the most retarded phase, such as setting the timing when the phase is on the advance side.

  In the first embodiment, after switching the duty ratio of the drive signal to “100%”, this is continued for a predetermined time T2, and instead of “100%” over a predetermined time (<T2). The execution of the operation control of the hydraulic control valve 28 and the execution of the operation control of the hydraulic control valve 28 at “0%” over a predetermined time (<T2) may be alternately repeated.

  In the second embodiment, the process of step S205 in FIG. 6 may be omitted as long as the hydraulic pressure in the advance side pressure chamber 24 can be appropriately reduced. In the same configuration, when the relative rotation phase of the camshaft 16 does not change to the advance side even if the operation control of the hydraulic control valve 28 with the duty ratio of “100%” is executed, the duty over the predetermined time T4 is set. The process of alternately repeating the operation control of the hydraulic control valve 28 when the ratio is “100%” and the operation control of the hydraulic control valve 28 when the duty ratio is “0%” over the predetermined time T5 is omitted. The In this case, the operation control of the hydraulic control valve 28 at the duty ratio of “100%” is continuously executed.

  In each embodiment, instead of setting the duty ratio of the drive signal to “100%” in the period from when the operation switch 52 is turned off until the engine rotational speed NE becomes “0”, “ A ratio lower than “100%” may be set. In short, it is only necessary that the operation control of the hydraulic control valve 28 can be executed in such a manner that the hydraulic oil is supplied to the advance side pressure chamber 24 and the hydraulic oil is discharged from the retard side pressure chamber 26.

  In each embodiment, instead of setting the duty ratio of the drive signal to “0%” in the period from when the operation switch 52 is turned off until the engine speed NE becomes “0”, “ A ratio higher than “0%” may be set. The point is that the operation control of the hydraulic control valve 28 may be executed in such a manner that the hydraulic oil is discharged from the advance side pressure chamber 24 and the hydraulic oil is supplied to the retard side pressure chamber 26.

  In each embodiment, each predetermined time ([T1 and T2] in the first embodiment, [T3 to T6] in the second embodiment) depends on the viscosity of the hydraulic oil and the index value of the same viscosity. May be variably set. In addition, as the index value of the viscosity of the hydraulic oil, the temperature of the hydraulic oil, the temperature of the engine cooling water, or the like can be employed. Here, when the viscosity of the hydraulic oil changes due to changes over time, temperature changes, etc., the hydraulic pressure drop rate of the advance side pressure chamber 24 and the hydraulic pressure drop rate of the retard side pressure chamber 26 also change accordingly. . In this regard, according to the above configuration, the engine stop time control process can be executed in accordance with the change in the pressure decrease rate accompanying the change in the viscosity of the hydraulic oil, and the lock mechanism 34 is shifted from the released state to the locked state. Can be executed properly.

  The present invention can also be applied to a valve timing control device having a lock mechanism that locks the relative rotational phase of the camshaft with respect to the crankshaft at the limit phase (the most advanced angle phase) on the advance side of the change range. . In this configuration, the adjustment mode in which the hydraulic oil is discharged from the advance side pressure chamber and the hydraulic oil is supplied to the retard side pressure chamber is the first mode, and the hydraulic oil is supplied to the advance side pressure chamber. At the same time, the adjustment mode in which the hydraulic oil is discharged from the retard side pressure chamber may be the second mode.

  The present invention can be applied not only to the valve timing control device that changes the valve timing of the intake valve, but also to the valve timing control device that changes the valve timing of the exhaust valve.

  DESCRIPTION OF SYMBOLS 10 ... Variable valve timing mechanism, 12 ... Housing, 14 ... Vane body, 16 ... Cam shaft, 18 ... Cam pulley, 20 ... Vane, 22 ... Groove, 24 ... Advance angle side pressure chamber, 26 ... Delay angle side pressure chamber, 28 DESCRIPTION OF SYMBOLS ... Hydraulic control valve, 30 ... Oil pump, 32 ... Electronic control unit, 34 ... Lock mechanism, 36 ... Housing hole, 36a ... Step part, 38 ... Lock pin, 38a ... Step part, 40 ... Coil spring, 42, 50 ... Unlocking pressure chamber, 44 ... retard angle side oil passage, 46 ... advance angle side oil passage, 48 ... lock hole, 52 ... operation switch, 54 ... battery, 56 ... relay.

Claims (6)

A variable valve timing mechanism that changes the relative rotation phase of the camshaft with respect to the crankshaft to a target phase based on the hydraulic pressure supplied to the advance side pressure chamber and the retard side pressure chamber, and the relative rotation phase when the hydraulic pressure is low. A valve timing control device for an internal combustion engine, comprising: a lock mechanism that locks at a limit phase of the change range, and a lock mechanism that releases the lock state when the hydraulic pressure increases;
In the first aspect, the relative rotation phase is changed to a side closer to the limit phase in a period from when the stop operation for stopping the operation of the internal combustion engine is started until the rotation of the crankshaft is stopped. A valve timing control for an internal combustion engine, comprising execution means for executing both the adjustment of the oil pressure and the adjustment of the oil pressure in a second mode in which the relative rotational phase is changed to a side away from the limit phase. apparatus. The valve timing control apparatus for an internal combustion engine according to claim 1,
The execution means executes the hydraulic pressure adjustment in the first mode until the relative rotational phase reaches the limit phase, and executes the hydraulic pressure adjustment in the second mode when the relative rotational phase reaches the limit phase. A valve timing control device for an internal combustion engine, characterized by comprising: The valve timing control apparatus for an internal combustion engine according to claim 1,
The execution means starts executing the hydraulic pressure adjustment in the second mode with the start of the stop operation, and the second mode when the relative rotation phase changes to a phase away from the limit phase. The valve timing control apparatus for an internal combustion engine, wherein the hydraulic pressure adjustment in the first mode is executed by temporarily interrupting the hydraulic pressure adjustment in the engine. The valve timing control apparatus for an internal combustion engine according to claim 3,
When the hydraulic pressure adjustment is performed in the second mode, the execution means is configured to continue the predetermined rotation for a predetermined period when the relative rotation phase does not change to a phase on the side away from the limit phase for a predetermined period. The valve timing control device for an internal combustion engine, wherein the hydraulic pressure adjustment in the second mode is interrupted and the hydraulic pressure adjustment in the first mode is executed. In the valve timing control device for an internal combustion engine according to any one of claims 1 to 4,
The limit phase is a retard phase limit phase with respect to the relative rotational phase,
The first aspect is an adjustment aspect in which hydraulic oil is discharged from the advance side pressure chamber and hydraulic oil is supplied to the retard side pressure chamber,
The valve timing control device for an internal combustion engine, wherein the second mode is an adjustment mode in which hydraulic oil is supplied to the advance side pressure chamber and hydraulic oil is discharged from the retard side pressure chamber. In the internal combustion engine valve timing control device according to any one of claims 1 to 5,
The valve timing control device for an internal combustion engine, wherein the stop operation is a stop operation in response to an operation switch being operated to stop the operation of the internal combustion engine.

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