JP4244701B2 - 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 that variably sets an opening / closing timing (valve timing) of a valve that is opened / closed by the camshaft by changing a relative rotation phase of the camshaft with respect to the crankshaft. The present invention relates to a valve timing control device for an internal combustion engine having a lock mechanism that restricts and locks a rotational phase changing operation through mechanical engagement.
[0002]
[Prior art]
Some internal combustion engines for vehicles are provided with a valve timing control device that appropriately changes the valve timing of the engine in order to improve output and emission. Such a valve timing control device 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. The housing and the vane body are, for example, about the camshaft as an axis. It is arranged to be relatively rotatable. A vane extending in the radial direction is formed in the vane body, and the interior of the housing is partitioned into an advance side pressure chamber and a retard side pressure chamber by the vane.
[0003]
These pressure chambers are respectively supplied with regulated hydraulic oil, and the oil pressure acts on the vanes, 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. And the valve timing of the same engine is changed by changing the relative rotation phase of the camshaft in this way.
[0004]
Further, as such a valve timing control device, one having a lock mechanism that mechanically locks the relative rotation phase of the camshaft with a predetermined lock phase is well known (see, for example, Patent Document 1). In the valve timing control device provided with this lock mechanism, the valve timing can be maintained at a timing suitable for the engine operating state even when the supply pressure of hydraulic oil cannot be sufficiently ensured, such as at the time of engine start.
[0005]
The lock mechanism includes, for example, a lock pin that is removably disposed in a receiving hole formed in the vane body, a recess (lock hole) into which the tip of the lock pin is inserted, and biases the lock pin toward the lock hole. Configured with a spring or the like. In the vane body, a lock releasing pressure chamber is formed in the vicinity of the accommodation hole. This pressure chamber communicates with each of the pressure chambers and is supplied with a part of the hydraulic oil, and a biasing force having a magnitude corresponding to the hydraulic pressure (unlocking pressure) of the hydraulic oil acts on the lock pin. The lock pin is biased to the side away from the lock hole.
[0006]
In such a lock mechanism, the lock pin is brought into a projecting state, that is, a locked state and a released state in which the lock pin is released in accordance with the magnitude relationship between the urging force of the spring and the urging force based on the hydraulic pressure of the hydraulic oil.
[0007]
For example, when the supply pressure of the oil pump decreases to a predetermined pressure (lock pressure) or less as the engine stops, the urging force of the spring exceeds the urging force based on the unlocking pressure. As a result, the lock pin moves to the lock hole side by the urging force of the spring, and the tip end portion is inserted into the lock hole. As a result, the lock mechanism is locked, and relative rotation between the housing and the vane body is regulated by the lock mechanism.
[0008]
On the other hand, when the engine is started, the operation of the oil pump is resumed, and the hydraulic pressure of the hydraulic oil supplied from the oil pump to the advance and retard pressure chambers gradually increases, so that the unlocking pressure reaches a predetermined pressure or higher. When it rises, the urging force based on the unlocking pressure exceeds the urging force of the spring. As a result, the lock pin moves to the side away from the lock hole by the urging force based on the unlocking pressure, and the tip portion thereof 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. Then, 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, the valve timing is adjusted based on the pressure adjustment between the retard side pressure chamber and the advance side pressure chamber. Changes will be made.
[0009]
[Patent Document 1]
JP 2002-317610 A (FIG. 1, page 5)
[0010]
[Problems to be solved by the invention]
By the way, normally, when shifting from the locked state to the released state, the lock mechanism is maintained in the released state by the hydraulic pressure supplied to each of the pressure chambers. It fluctuates due to various factors such as the influence of rotational pulsation. For this reason, even after the lock pin has been completely removed from the lock hole and shifted to the release state, the hydraulic pressure temporarily decreases due to the influence of these factors, and the lock pin is reinserted into the lock hole. It may end up.
[0011]
Furthermore, if hydraulic pressure is supplied to the pressure chambers to rotate the housing and the vane body relative to each other in this state, the lock pin is pressed against the inner wall of the lock hole, and an excessive contact pressure is generated between them. As a result, there is a risk that smooth detachment of the lock pin may be hindered. As a result, it may be impossible to change the valve timing over a long period thereafter.
[0012]
In addition, the above-described inconveniences cannot be avoided in an apparatus including a lock mechanism that restricts the relative rotational phase changing operation through mechanical engagement, not limited to an apparatus including a lock mechanism.
[0013]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an internal combustion engine capable of early recovery from the malfunction even when the malfunction of the lock mechanism occurs. The object is to provide a valve timing control device.
[0014]
[Means for Solving the Problems]
In the following, means for achieving the above object and its effects are described.
First, the invention according to claim 1 is a valve timing variable mechanism that changes the relative rotational phase of the camshaft with respect to the crankshaft to a target phase based on the pressure of the fluid supplied to the advance side pressure chamber and the retard side pressure chamber. And a lock state in which the change operation of the relative rotation phase by the valve timing variable mechanism is regulated through mechanical engagement to lock the relative rotation phase to a predetermined lock phase, the advance side pressure chamber, and the retard side In a valve timing control device for an internal combustion engine having a lock mechanism that is selectively switched to a released state in which the lock is released by the fluid pressure in the pressure chamber, the relative rotation phase is changed by the valve timing variable mechanism. And the lock mechanism is in a locked state. Incorrect locking state of the locking mechanism Detecting means for detecting The wrong When it is detected that the locked state is detected, at least one fluid pressure in each of the pressure chambers is temporarily changed so that the rotational force for changing the relative rotational phase to the target phase is reduced, and then the fluid pressure is changed. And a fluid pressure control means for gradually returning the gas to the original state.
[0015]
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, when the fluid pressure control means detects that the lock mechanism is locked by the detection means, Changing the fluid pressure of at least one of the pressure chambers so that the relative rotation phase is changed with the lock phase as a target phase, and then gradually returning the fluid pressure to the original state. The gist.
[0016]
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, when the fluid pressure control means detects that the lock mechanism is locked by the detection means, At least one fluid pressure in each of the pressure chambers is temporarily changed so that a rotational force opposite to the rotational force for changing the relative rotational phase to the target phase is generated, and then the fluid pressure is returned to the original state. The gist is to gradually return.
[0017]
If the operation of changing the relative rotational phase of the camshaft is performed by the variable valve timing mechanism without completely releasing the locked state by the locking mechanism, an excessive contact pressure is applied to the engagement portion that restricts the change of the relative rotational phase in the locking mechanism. Acts and hinders its smooth operation.
[0018]
In this regard, in the configuration of claim 1, the rotational force for changing the relative rotational phase to the target phase is reduced, and in the configuration of claim 2, the relative rotational phase is set with the lock phase as the target phase. Further, in the configuration according to claim 3, the advance side pressure chamber and the retard side pressure are respectively set so that a rotational force opposite to the rotational force for changing the relative rotational phase to the target phase is generated. The fluid pressure of at least one of the chambers is once changed, and then the fluid pressure is gradually returned to the original state.
[0019]
With any of these configurations, the contact pressure at the engagement portion of the lock mechanism can be weakened, thereby ensuring smooth operation of the engagement portion and promptly releasing the restriction (lock) by the lock mechanism. Is possible. In addition, when the fluid pressure is restored to the original state, the restoration is gradually performed, so that the contact pressure is excessively increased with the operation of changing the relative rotational phase by the variable valve timing mechanism. The lock by the lock mechanism can be released before. Therefore, even when a malfunction of the lock mechanism occurs, an early recovery from the malfunction can be achieved.
[0020]
Specifically, as the lock mechanism, as described in claim 4, a first rotating body that is drivingly connected to one of the crankshaft and the camshaft, and a second that is drivingly connected to the other of them. A variable timing timing mechanism including a rotating body of the first rotating body, and a locking state is achieved by engaging the tip of a lock pin provided in the first rotating body with a recess formed in the second rotating body, It is possible to employ a lock mechanism that is brought into a released state by urging the lock pin toward the side away from the recess by the fluid pressure of each pressure chamber and releasing the engagement.
[0021]
According to this configuration, when an excessive contact pressure acts between the outer wall of the lock pin and the inner wall of the recess and the smooth operation of the lock pin is hindered, the contact pressure can be reduced. It is possible to quickly release the lock by the lock mechanism while ensuring the smooth operation of the pin.
[0022]
According to a fifth aspect of the present invention, in the valve timing control device for an internal combustion engine according to any one of the first to fourth aspects, the fluid pressure control means indicates that the lock mechanism is locked by the detection means. The gist of the present invention is to repeatedly execute a series of operations for returning to the original state after changing the fluid pressure once on the condition that the detection is made.
[0023]
According to the above configuration, even if the engagement portion of the lock mechanism is brought into close contact with the contact pressure and is difficult to separate, even if the lock is not released even if the contact pressure is weakened, The contact state can be eliminated by shaking the part. As a result, even in such a case, it is possible to promptly release the lock.
[0024]
In this way, in the series of operations for once returning the fluid pressure after the fluid pressure is changed, the most advanced angle phase or the most retarded angle phase is set as the lock phase, as in the configuration according to claim 6. It can be applied to a device to be used.
[0025]
The invention according to claim 7 is the valve timing control apparatus for an internal combustion engine according to any one of claims 1 to 6, wherein the detecting means detects the target when the lock mechanism is in a locked state. The gist is that the elapsed time after the phase is changed from the lock phase exceeds a predetermined time.
[0026]
Changing the relative rotational phase In a state of action and The lock mechanism is in the locked state, that is, the erroneous lock by the lock mechanism is detected by detecting that the actual relative rotational phase is in the lock phase even though the target phase has changed from the lock phase. Can do. Here, since the relative rotational phase changes with a response delay with respect to the change of the target phase, it is desirable to consider such a response delay in order to more accurately detect that the lock mechanism is in the locked state. . On the other hand, according to the above configuration, the detection can be performed in consideration of such a response delay, and the detection can be performed with high accuracy.
[0027]
The invention according to claim 8 is the valve timing control device for an internal combustion engine according to any one of claims 1 to 7, wherein the fluid pressure uses an engine-driven pump as its pressure source, and the detection is performed. The gist is that the means is that the engine speed is low when detecting that the locked state is established.
[0028]
The discharge pressure of the engine-driven pump changes according to the engine speed. For this reason, in an apparatus using an engine-driven pump as the fluid pressure source, the fluid pressure decreases as the engine rotational speed decreases. An erroneous lock by the lock mechanism occurs when the fluid pressure is excessively reduced due to the engine rotational speed being lowered. On the other hand, according to the above configuration, since it is detected that the erroneous lock is made only when the engine speed is low, the detection can be performed more accurately.
[0029]
The invention according to claim 9 is the valve timing control device for an internal combustion engine according to any one of claims 1 to 8, wherein the temperature of the fluid is detected when the detection means detects that the lock state is established. The gist is to be high.
[0030]
As the temperature of the fluid increases, the viscosity decreases, and accordingly, the amount of fluid leakage from the fluid pressure circuit increases, so the fluid pressure in each pressure chamber also decreases. The erroneous lock also occurs when the fluid temperature is increased and the fluid pressure is excessively lowered. On the other hand, according to the above configuration, since the erroneous lock is detected only when the temperature of the fluid or the correlation temperature thereof is high, the detection can be performed more accurately. it can.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which a valve timing control device according to the present invention is embodied will be described.
[0032]
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, and the housing 12 is connected to a cam pulley 18 that rotates in synchronization with a crankshaft of the internal combustion engine, so as to be integrally rotatable. In the present embodiment, the housing 12 functions as a first rotating body, and the vane body 14 functions as a second rotating body. In this example, it is assumed that the camshaft 16 rotates in the clockwise direction in FIG.
[0033]
A plurality of vanes 20 extending in the radial direction 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, this number may be changed suitably.
[0034]
The advance-side pressure chamber 24 and the retard-side pressure chamber 26 are connected to a hydraulic control valve 28 through appropriate oil passages, respectively, and the hydraulic control valve 28 is driven by an engine connected to a crankshaft. Fluid (operating oil) sent from the oil pump 30 of the type is supplied. 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 side. The pressure chamber 24 and the retard side pressure chamber 26 are discharged. The vane 20 has a relative rotation phase in the groove portion 22 due to a difference in fluid pressure between the advance side pressure chamber 24 and the retard side pressure chamber 26 formed on both side surfaces thereof, that is, a difference in hydraulic pressure. 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 valve timing of the intake valve is changed.
[0035]
The duty ratio of the drive signal is adjusted in the range of “0% to 100%”, and the relative rotation phase is quickly changed to the advance side as the duty ratio approaches “100%”. 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%”.
[0036]
Specifically, such valve timing control is performed as follows.
The electronic control unit 32 includes a coolant temperature THW detected by a water temperature sensor, a rotational phase of the camshaft 16 detected by a cam angle sensor, a rotational phase of the crankshaft detected by a crank angle sensor, an engine rotational speed NE, and the like. A parameter representing the engine operating state is input.
[0037]
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.
[0038]
When the target phase is different from the current phase, the electronic control device 32 discharges the hydraulic oil from either the advance side pressure chamber 24 or the retard side pressure chamber 26 and the hydraulic oil to the other side. The hydraulic control valve 28 is controlled to be supplied. The vane body 14 rotates relative to the housing 12 in accordance with the pressure difference between the advance-side pressure chamber 24 and the retard-side pressure chamber 26 which is generated as a result, and the valve timing is adjusted.
[0039]
As a result of such adjustment, when the target phase matches the current phase, the electronic control device 32 causes the hydraulic control valve 28 to stop supplying and discharging hydraulic oil to the advance side pressure chamber 24 and the retard side pressure chamber 26. To control the operation. As a result, the pressures in the advance side pressure chamber 24 and the retard side pressure chamber 26 are kept even, and the relative rotation phase of the vane body 14 is also maintained.
[0040]
In this valve timing variable mechanism, the vane body 14 can be relatively rotated in a range from a phase in which the vane 20 contacts one side wall of the groove 22 to a phase in contact with the opposite side wall of the groove 22. It has become. That is, the range of the phase in which the relative rotation is possible becomes the control range of the rotation phase in the valve timing control device. In the following, the relative rotational phase of the camshaft 16 when the vane body 14 rotates relative to the most retarded direction (the direction opposite to the rotational direction of the camshaft 16), that is, the control limit phase on the retarded side of the control range. 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 in the most advanced direction (the rotational direction of the camshaft 16), that is, the control limit phase on the advanced side of the control range is referred to as the “most advanced angle phase”.
[0041]
As described above, in the valve timing control apparatus of the present embodiment, the relative rotation phase of the camshaft 16 is changed from the “most retarded phase” to the “most retarded phase” based on the pressure control of the advance side pressure chamber 24 and the retard side pressure chamber 26. It is changed as appropriate within the range up to “the most advanced angle phase”. With this change control, the opening / closing timing (valve timing) of the intake valve that is driven to open / close as the camshaft 16 rotates is made variable.
[0042]
In addition, 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 pressure drops, such as when the engine is started.
[0043]
That is, one of the vanes 20 has a stepped accommodation hole 36 extending in parallel with the axial direction of the camshaft 16, and a lock pin 38 can be projected and retracted in the space inside the accommodation hole 36. It is arranged.
[0044]
As shown in FIGS. 2 and 3, the lock pin 38 has the outer peripheral surface in sliding contact with the inner peripheral surface of the receiving hole 36 to the position shown in FIG. The camshaft 16 (FIG. 1) moves 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.
[0045]
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 lock pin 38 is inserted into the lock hole 48 by the biasing force of the coil spring 40, the vane body 14 is mechanically fastened to the housing 12, and its relative rotation is restricted ( Locked).
[0046]
A space formed by the lock hole 48 and the tip of the lock pin 38 is a lock release pressure chamber 50, and an advance side oil passage 46 formed on the sliding contact surface between the vane 20 and the housing 12. Is connected to the advance angle side pressure chamber 24 through which the pressure in the advance angle side pressure chamber 24 is transmitted.
[0047]
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 pressure in one or both of the advance side pressure chamber 24 and the retard side pressure chamber 26 increases and the pressure in the lock release pressure chambers 42 and 50 connected thereto increases sufficiently, as shown in FIG. In addition, the lock pin 38 moves in a direction away from the lock hole 48, and the lock of the relative rotation is released.
[0048]
As described above, in the valve timing control apparatus of the present embodiment, the relative rotation of the vane body 14 is locked at a predetermined lock phase (most retarded angle phase) when the pressure decreases immediately after the engine is started, and the oil pump 30 operates sufficiently. When the oil can be supplied, the lock of the relative rotation is released so that the valve timing can be controlled.
[0049]
In the lock mechanism 34 of the present embodiment, when only the pressure in the retard side pressure chamber 26 (the lock release pressure chamber 42) is increased, the lock is caused by the pressure being equal to or higher than the predetermined pressure Pa. The pin 38 can be detached from the lock hole 48. On the other hand, when the pressure in the advance side pressure chamber 24 (the pressure release pressure chamber 50) is increased, the lock pin 38 can be detached by the pressure being equal to or higher than the predetermined pressure Pb lower than the predetermined pressure Pa. Become. That is, by increasing the pressure in the advance side pressure chamber 24, the lock pin 38 is disengaged, that is, the lock is released more quickly than when increasing the pressure in the retard side pressure chamber 26.
[0050]
Further, when the operation control of the hydraulic control valve 28 is not performed, the hydraulic circuit is configured so that the oil pump 30 and the retard side pressure chamber 26 communicate with each other. Therefore, when the hydraulic control valve 28 is not operating when the engine is started, the hydraulic oil is supplied from the oil pump 30 toward the retard side pressure chamber 26, and at this time, the direction in which the lock pin 38 is removed from the lock hole 48. A preload is applied. After that, by supplying hydraulic oil to the advance side pressure chamber 24, the hydraulic pressure is surely applied to the unlocking pressure chambers 42 and 50 to ensure the pressure rise, and the lock mechanism 34 is securely locked. To be released.
[0051]
In this embodiment, when the lock mechanism 34 is in a locked state during the operation of changing the relative rotational phase of the camshaft 16, that is, when the lock mechanism 34 is erroneously locked, the lock is released. In order to achieve this, the release control described below is executed.
[0052]
Processing related to the release control will be described with reference to the flowchart shown in FIG.
The series of processes shown in this flowchart shows a specific processing procedure of the release control process, and is executed by the electronic control unit 32 as a process for each predetermined cycle.
[0053]
As shown in FIG. 4, in this process, it is first determined whether or not the erroneous lock is performed. Specifically, it is determined whether or not all of the following conditions (Condition A) to (Condition E) are satisfied (Steps S100 to S108), and when all these conditions are satisfied, an erroneous lock is made. Is detected.
(Condition A) Advance angle is requested (step S100).
(Condition b) The coolant temperature THW is higher than the predetermined temperature TH1 (step S102).
(Condition C) The engine speed NE is lower than the predetermined speed N1 (step S104).
(Condition d) The relative rotation phase of the camshaft 16 is the lock phase (step S106).
(Condition E) The elapsed time after the target phase has changed from the lock phase exceeds the predetermined time T1 (step S108).
[0054]
It should be noted that the predetermined temperature TH1, the predetermined speed N1, and the predetermined time T1 are obtained through experiments and the like so as to be able to accurately detect that the lock mechanism 34 has been erroneously locked. Is remembered. In the present embodiment, the processes in steps S100 to S108 are performed to change the relative rotational phase. Is in a state of being changed and Lock mechanism is locked Incorrect lock state of the lock mechanism Functions as a detecting means for detecting.
[0055]
Here, when the erroneous lock is performed, the actual relative rotation phase does not change from the lock phase even though the target phase for the relative rotation phase of the camshaft 16 is changed from the lock phase. Will occur. Therefore, by monitoring the occurrence of such a phenomenon, it is possible to detect that an erroneous lock has been made. Since the actual relative rotational phase changes with a response delay with respect to the change in the target phase, in order to accurately detect the occurrence of erroneous lock, it takes some time after the target phase changes from the lock phase. It is desirable to monitor the occurrence of the above phenomenon after placing
[0056]
In this process, considering these points, the above (Condition A), (Condition D), and (Condition E) are set. Then, after an advance angle request is made through these conditions (step S100: YES), the state where the actual relative rotational phase is in the lock phase (step S106: YES) continues beyond the predetermined time T1 (step S106: YES). Step S108: YES), it is detected that an erroneous lock has been made.
[0057]
Further, it has been confirmed by the inventors that such an erroneous lock occurs when the temperature of the hydraulic oil is high or the engine rotational speed NE is low. This is due to the following reasons.
[0058]
That is, first, when the temperature of the hydraulic oil increases, the viscosity thereof decreases, and accordingly, the amount of hydraulic oil leaked from the hydraulic circuit increases, so that the pressure in each of the pressure chambers 24 and 26 decreases. When the temperature of the hydraulic oil becomes high and the pressure is excessively reduced in this way, the disengaged state of the lock pin 38 from the lock hole 48 cannot be maintained, and the erroneous lock is performed. .
[0059]
On the other hand, the engine rotational speed NE pulsates such that the air-fuel mixture is combusted in each cylinder of the internal combustion engine and is accelerated when rotational torque is applied, and is decelerated when such rotational torque is not applied. Along with the rotational pulsation, the discharge pressure of the engine-driven oil pump 30 also pulsates. Further, when the engine rotational speed NE is low, the interval of each combustion performed intermittently becomes long, so that the amplitude of the pulsation tends to increase. Further, at this time, the rotational speed of the oil pump 30 is also low and the discharge pressure is low. Since the average value is low, the minimum value of the discharge pressure is also very low. And when such a drop in the discharge pressure becomes excessive, it causes an excessive drop in the pressure in each of the pressure chambers 24 and 26 using this as a pressure source, and the disengaged state of the lock pin 38 cannot be maintained. The erroneous lock is made.
[0060]
In this process, the above (Condition B) and (Condition C) are set based on such a situation. Specifically, when the coolant temperature THW as the correlation temperature that suitably reflects the temperature of the hydraulic oil is higher than the predetermined temperature TH1 (step S102: YES), and the engine speed NE is lower than the predetermined speed N1. Only in this case (step S104: YES), it is detected that the erroneous lock has been made. As a result, it is possible to prevent the detection from being performed when an erroneous lock does not occur, and to perform the detection accurately.
[0061]
If any one of the above (Condition A) to (Condition E) is not satisfied (“NO” in any one of Steps S100 to S108), it is assumed that an erroneous lock has not been made. This process is temporarily terminated without executing the following process.
[0062]
Thereafter, this process is repeatedly executed, and when all of the above conditions are satisfied (steps S100 to S108 are all “YES”), it is detected that an erroneous lock has been made, and recovery from the locked state is performed. A process (step S112) for illustration is executed. In the present embodiment, the process of step S112 functions as a fluid pressure control unit that temporarily changes the fluid pressure and then gradually returns the fluid pressure to the original state.
[0063]
Prior to the execution of the return process, it is determined whether or not the return process has been continuously executed “N” times or more (step S110). At this time, assuming that the return process has never been executed (step S110: NO), the return process is executed (step S112).
[0064]
Hereinafter, the return process will be described.
If the pressures of the pressure chambers 24 and 26 are adjusted to advance the relative rotational phase of the camshaft 16 in the state of being erroneously locked, these pressures cause the vane body 14 to rotate relative to the housing 12 at this time. Acts to move. As a result, as shown in FIG. 5, the lock pin 38 is pressed against the inner wall of the lock hole 48, and an excessive contact pressure acts on the contact surface Y between the lock pin 38 and the lock hole 48. Smooth operation is hindered.
[0065]
Here, when the relative rotation phase of the camshaft 16 reaches the most retarded phase, the vane 20 comes into contact with one side wall of the groove 22 and the relative rotation of the vane body 14 toward the retarded side is restricted. At this time, the lock pin 38 can be inserted into the lock hole 48 and removed from the lock hole 48 in a state where the mechanical constraints are minimized (the state shown in FIG. 6). The mechanism 34 is set.
[0066]
Therefore, in this return processing, first, as shown in FIG. 7, the duty ratio of the drive signal is temporarily changed from “100%” in this example to “0%” (time). t1), the state is maintained for a predetermined time (time t1 to t2). Thereby, a rotational force opposite to the rotational force for changing the relative rotational phase of the camshaft 16 to the target phase is generated, and the pressing of the lock pin 38 against the inner wall of the lock hole 48 is released.
[0067]
At this time, when the pressure is increased to the same pressure, only the pressure in the retarded-side pressure chamber 26, which is weaker than the pressure in the advanced-side pressure chamber 24 and acts to release the lock pin 38, is increased. Yes. Therefore, in order to reliably release the lock pin 38, it is desirable to increase the pressure ratio of the advance angle side pressure chamber 24 by increasing the duty ratio of the drive signal.
[0068]
However, at this time, if the duty ratio of the drive signal is instantaneously increased to a ratio commensurate with the engine operating state to increase the pressure in the advance side pressure chamber 24, the force acting to release the lock pin 38 accordingly. However, at the same time, a rotational force that relatively rotates the vane body 14 toward the advance side is also generated. This reproduces the above phenomenon and prevents the lock pin 38 from being detached.
[0069]
For this reason, in this return processing, when the duty ratio is returned from “0%” to a ratio corresponding to the engine operating state, the duty ratio is returned stepwise by a predetermined ratio α every time a predetermined time elapses. (Time t2 to t4). Specifically, first, the lock pin 38 can be detached, but the pressure in the advance side pressure chamber 24 is increased to such an extent that a rotational force that causes the vane body 14 to rotate relatively is not generated. 38 is released (time t2 to t3). Thereafter, the pressure in the advance side pressure chamber 24 is further increased to generate the rotational force, and the vane body 14 is rotated relative to the advance side (time t3 to t4). As a result, the lock by the lock mechanism 34 can be released before the contact pressure rises excessively with the change operation of the relative rotational phase.
[0070]
After such a return process is executed, after the control related to the change of the valve timing is returned to the normal control based on the engine operating state (step S114), this process is temporarily ended.
[0071]
Then, even after the return process is executed in this way, if the erroneous lock by the lock mechanism 34 is not released (all of steps S100 to S108 are “YES”), the return process (step S112) is repeated. Executed. Note that this is permitted on condition that the number of continuous executions of the return process is equal to or less than the predetermined number “N” (step S110: NO).
[0072]
By repeatedly executing the return process in this manner, the opportunity to release the lock pin 38 is increased. In addition to this, there are the following actions. When the return process is executed, the lock pin 38 and the lock hole 48 are brought into close contact with each other by the contact pressure on the contact surface Y (FIG. 5), and they are difficult to separate. May not be removed from the lock hole 48. On the other hand, by repeatedly executing the return process, the lock mechanism 34 is shaken and the contact state is resolved. If the erroneous lock is not released even though the return process has been repeated “N” times (step S110: NO), an abnormality has occurred in the valve timing control device with the “ON” operation. After the abnormality flag to be judged is operated “ON” (step S116), this process is temporarily ended.
[0073]
As described above, according to the present embodiment, the effects described below can be obtained.
(1) When it is detected that the lock mechanism 34 is erroneously locked, each pressure is generated so that a rotational force opposite to the rotational force for changing the relative rotational phase of the camshaft 16 to the target phase is generated. The pressures in the chambers 24 and 26 were once changed, and then the pressures were gradually returned to the original state. For this reason, the contact pressure between the lock pin 38 and the lock hole 48 can be weakened, so that the smooth operation of the lock pin 38 can be secured and the erroneous lock can be quickly released. In addition, when the pressure in each of the pressure chambers 24 and 26 is returned to the original state, the return is gradually performed, so that the contact pressure rises excessively as the relative rotational phase is changed. Before that, the lock by the lock mechanism 34 can be released. Therefore, even when a malfunction of the lock mechanism 34 occurs, an early recovery from the malfunction can be achieved.
[0074]
(2) If the erroneous lock by the lock mechanism 34 is not canceled even if the return control is executed, the return process is repeatedly executed. For this reason, the lock pin 38 and the lock hole 48 are brought into close contact with each other due to the contact pressure, and they are difficult to be separated from each other, and the lock mechanism 34 is not released even when the contact pressure is weakened. It is possible to eliminate the contact state by shaking. As a result, even in such a case, it is possible to promptly release the lock.
[0075]
(3) On the condition that the elapsed time after the target phase is changed from the lock phase exceeds the predetermined time T1, it is detected that the lock mechanism 34 is erroneously locked. For this reason, the above detection can be performed in consideration of the response delay of the change in the actual relative rotational phase with respect to the change in the target phase. If the lock mechanism 34 is in the released state, the detection is erroneously performed. It is possible to suitably suppress the detection.
[0076]
(4) Since the detection is performed only when the engine speed NE is lower than the predetermined speed N1, the detection can be performed more accurately.
(5) Since the above detection is performed only when the coolant temperature THW is high, the detection can be performed more accurately.
[0077]
The embodiment described above may be modified as follows.
In the above embodiment, if it is possible to accurately detect that the lock mechanism 34 is erroneously locked, (condition b) and (condition c) may be omitted, (Condition D) and (Condition E) may be arbitrarily changed.
[0078]
In the above embodiment, the duty ratio of the drive signal is temporarily changed to “0%” when executing the return process. Instead, the duty ratio and thus the pressure in each of the pressure chambers 24 and 26 are temporarily changed so as to change the relative rotation phase of the camshaft 16 to the lock phase, for example, by temporarily changing the target phase to the lock phase. It may be. Further, the duty ratio is changed to a ratio lower than the ratio commensurate with the target phase so that the rotational force for changing the relative rotational phase of the camshaft 16 to the target phase is reduced. The pressure may be changed once. Also with these configurations, the contact pressure between the lock pin 38 and the lock hole 48 can be weakened.
[0079]
In the above embodiment, when the pressure in each of the pressure chambers 24 and 26 is restored to the original state, the duty ratio of the drive signal is restored stepwise by a predetermined ratio α to a ratio corresponding to the engine operating state. did. However, the present invention is not limited to this, and the duty ratio may be continuously returned at a predetermined change rate, for example, as shown in FIG.
[0080]
In the above embodiment, the return process is repeatedly executed when the erroneous lock of the lock mechanism 34 is not released even if the return control is executed. However, the return process may be executed only once.
[0081]
-Between the locked state in which the operation of changing the relative rotational phase is regulated through mechanical engagement and the relative rotational phase is locked to the locked phase, and the unlocked state in which the lock is released by the pressure of each pressure chamber 24, 26. Any lock mechanism whose state can be selectively switched can be employed instead of the lock mechanism 34 of the above-described embodiment.
[0082]
In the above embodiment, the present invention is applied to the valve timing control device including the lock mechanism 34 that locks the relative rotation phase of the camshaft 16 that drives the intake valve with the lock phase (the most retarded angle phase). . The present invention is also applicable to a valve timing control device having a lock mechanism that locks the relative rotational phase of a camshaft that drives an exhaust valve at a predetermined lock phase (maximum advance angle phase). In addition, the present invention is applicable not only to the most advanced phase and the most retarded phase, but also to a valve timing control device having a lock mechanism that locks with a lock phase intermediate between the most retarded phase and the most advanced angle phase. It is.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention.
FIG. 2 is a sectional view showing a sectional structure of the locking mechanism according to the embodiment;
FIG. 3 is a sectional view showing a sectional structure of the locking mechanism according to the embodiment;
FIG. 4 is a flowchart showing a processing procedure when executing a release control process according to the embodiment;
FIG. 5 is a schematic diagram illustrating an example of an operation mode of a lock mechanism.
FIG. 6 is a schematic diagram illustrating an example of an operation mode of a lock mechanism.
FIG. 7 is a timing chart showing how to set the duty ratio of the drive signal in the return processing according to the embodiment;
FIG. 8 is a timing chart showing a modification example of the setting mode.
[Explanation of symbols]
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 oil passage, 46 ... advance angle oil passage, 48 ... lock hole.

Claims (9)

A valve timing variable mechanism that changes the relative rotational phase of the camshaft with respect to the crankshaft to a target phase based on the pressure of the fluid supplied to the advance side pressure chamber and the retard side pressure chamber, and the relative position by the valve timing variable mechanism The lock is released by the locked state in which the change operation of the rotation phase is regulated through mechanical engagement and the relative rotation phase is locked to a predetermined lock phase, and the fluid pressure of the advance side pressure chamber and the retard side pressure chamber. A valve timing control device for an internal combustion engine having a lock mechanism that is selectively switched to a released state,
Detecting means for detecting an erroneous lock state of the lock mechanism such that the operation of changing the relative rotational phase by the valve timing variable mechanism is performed and the lock mechanism is in a locked state;
When the detection means detects that the lock mechanism is in the erroneous lock state, at least one fluid in each pressure chamber is reduced so that the rotational force for changing the relative rotation phase to the target phase decreases. A valve timing control device for an internal combustion engine, comprising: fluid pressure control means for temporarily changing the pressure and then gradually returning the fluid pressure to the original state. The fluid pressure control means detects at least one of the pressure chambers so that the relative rotation phase is changed with the lock phase as a target phase when the detection means detects that the lock mechanism is in a locked state. The valve timing control device for an internal combustion engine according to claim 1, wherein the fluid pressure is once changed, and then the fluid pressure is gradually returned to the original state. When the fluid pressure control means detects that the lock mechanism is in a locked state by the detection means, the fluid pressure control means generates a rotational force opposite to a rotational force for changing the relative rotational phase to a target phase. 2. The valve timing control device for an internal combustion engine according to claim 1, wherein at least one fluid pressure in each pressure chamber is once changed, and then the fluid pressure is gradually returned to the original state. The valve timing variable mechanism includes a first rotating body that is drivingly connected to one of the crankshaft and the camshaft, and a second rotating body that is drivingly connected to the other.
The lock mechanism is brought into the locked state by engaging the tip of a lock pin provided in the first rotating body with a recess formed in the second rotating body, while the fluid pressure in each pressure chamber is The valve timing control device for an internal combustion engine according to any one of claims 1 to 3, wherein the release state is established by urging the lock pin toward the side away from the recess and releasing the engagement. The fluid pressure control means repeats a series of operations for changing the fluid pressure once and then returning to the original state, provided that the detection means detects that the lock mechanism is in the locked state. The valve timing control device for an internal combustion engine according to any one of claims 1 to 4, which is executed. 6. The valve timing control device for an internal combustion engine according to claim 1, wherein the lock phase is a most advanced angle phase or a most retarded angle phase. 7. The condition according to claim 1, wherein when the detection means detects that the lock mechanism is in a locked state, an elapsed time after the target phase changes from the lock phase exceeds a predetermined time. A valve timing control device for an internal combustion engine according to any one of the above. 8. The fluid pressure according to any one of claims 1 to 7, wherein the fluid pressure is obtained by using an engine-driven pump as a pressure source, and the engine speed is low when detecting that the detection means is in the locked state. A valve timing control device for an internal combustion engine according to claim 1. The valve timing control device for an internal combustion engine according to any one of claims 1 to 8, wherein the detection means detects that the fluid is in a locked state, and the temperature of the fluid is high.

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