JP2001152888A - Variable valve-timing control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the reliability of the variable valve-timing control by reducing the rate of occurrence of failed unlocking operation in a locking mechanism of a variable valve-timing device. SOLUTION: Unlocking control is conducted for a locking mechanism of a variable valve timing device, followed by a determination as to whether unlocking is generated correctly, and if it is a no, the failure relief control for a hydraulic control valve is conducted, and the motions to reciprocate the valve element of the control valve in prescribed strokes are repeated (steps 101-103). Thereby the control valve can be restituted to the normally operable condition by the failure relief control in the case the failed operation is of temporary type, for example originating from foreign matters biting into the control valve. Determination is made whether the control valve is in normal operation until the failure relief control is finished (step 104), and if the valve operation is normal, the unlocking control is re-conducted (step 106). If at this time, the locking mechanism is normal, unlocking can be generated by re- conducting the unlocking control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing control device for an internal combustion engine in which at least one of an intake valve and an exhaust valve of the internal combustion engine is provided with a variable valve timing device having a lock mechanism.

[0002]

2. Description of the Related Art In recent years, an internal combustion engine mounted on a vehicle has been increasingly employing a variable valve timing device for the purpose of improving output, reducing fuel consumption and reducing exhaust emissions. In general, a variable valve timing device uses a discharge oil pressure of an oil pump driven by an engine as a drive source, so that the valve timing cannot be maintained at a constant phase by the oil pressure until the oil pressure rises to some extent after the engine is started. For this reason, conventionally, a lock mechanism is provided in the variable valve timing device, and the engine is started in a state where the valve timing is mechanically locked to a fixed phase by the lock mechanism. On the other hand, the valve timing is variably controlled by the hydraulic control after the hydraulic pressure is released in the unlock direction and the lock is released.

[0003]

By the way, even if the lock release control is performed, the lock mechanism may not be unlocked for some reason. If the lock cannot be released, the lock release control is performed again. Can be considered. In this way, if the lock mechanism is temporarily unlocked due to a foreign object being caught in the lock mechanism or the like, the lock may be unlocked again by unlock control again. In addition to the failure, a malfunction of the hydraulic control valve may be considered. In the case of malfunction of the hydraulic control valve, even if the unlock control signal is output to the hydraulic control valve, the hydraulic control valve does not operate normally. Can not.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the rate of occurrence of a failure in unlocking a lock mechanism of a variable valve timing device. It is an object of the present invention to provide a variable valve timing control device for an internal combustion engine which can improve the reliability of the engine.

[0005]

In order to achieve the above object, a variable valve timing control apparatus for an internal combustion engine according to the present invention applies hydraulic pressure to a lock mechanism in an unlocking direction during unlocking control. After the hydraulic control valve is controlled by the lock release control means as described above, whether or not the lock mechanism is unlocked is determined by the lock release determination means. As a result, when it is determined that the lock has not been released, the unlock control is performed again after driving the hydraulic control valve according to the drive pattern of the abnormality release control.

As described above, according to the present invention, the hydraulic control valve is driven in accordance with the drive pattern of the abnormal release control before the lock release control is performed again. Then, the lock release control can be performed again after the hydraulic control valve is returned to a state in which the hydraulic control valve can be normally operated by the abnormality release control. For this reason, if the lock mechanism is normal, the lock can be released again by the lock release control, the occurrence rate of the lock release failure can be reduced as compared with the conventional case, and the reliability of the variable valve timing control is improved. be able to.

[0007] In this case, in the abnormality release control, the operation of reciprocating the valve element of the hydraulic control valve at a predetermined stroke may be repeated. With this configuration, in the case of a temporary malfunction due to a foreign object being caught by the hydraulic control valve or the like, the malfunction occurs while repeating the operation of reciprocating the valve body of the hydraulic control valve at a predetermined stroke by the abnormality release control. The cause (foreign matter, etc.) is removed and the hydraulic control valve returns to a state where it can operate normally.

Further, if the valve body of the hydraulic control valve operates normally when the hydraulic control valve is driven according to the drive pattern of the abnormal release control, a lock release failure due to a malfunction of the lock mechanism may occur. The determination may be made. In other words, the cause of the lock release failure is either the malfunction of the lock mechanism or the malfunction of the hydraulic control valve.If the valve body of the hydraulic control valve operates normally due to the abnormal release control, the hydraulic control valve will operate normally. Is confirmed, and it can be determined that the lock release is defective due to the operation failure of the lock mechanism.

At present, most variable valve timing systems that are in practical use control the advance of the valve timing of the intake valve in accordance with the operating state of the engine. Recently, however, in order to further improve the variable valve timing control performance, In addition, a device in which a variable valve timing device is provided for both an intake valve and an exhaust valve has been developed. In this device, if the variable valve timing control is performed in the state where the lock of the lock mechanism is not released, only the normally operating variable valve timing device operates normally, so the valve overlap amount of the intake and exhaust valves is abnormal. And the residual ratio of exhaust gas in the cylinder (internal EGR amount) may become excessive, whereby the combustion state in the cylinder deteriorates to cause misfire, drivability and exhaust emission deteriorate, In the worst case, engine stall may occur.

Therefore, when the present invention is applied to an internal combustion engine provided with a variable valve timing device for both the intake valve and the exhaust valve, it is determined that the lock is not released after the lock release control is completed. Until the lock release is detected again by the lock release control, the variable valve timing control of the normally operating variable valve timing device is stopped or the residual ratio of exhaust gas in the cylinder is reduced. Good to control. In this way, even if the time for the abnormality release control is prolonged, the variable valve timing control of the normally operating variable valve timing device is stopped or the in-cylinder is stopped until the lock release is detected. Since the control is performed to reduce the residual ratio of exhaust gas, it is possible to suppress an increase in the residual ratio of exhaust gas in the cylinder during the abnormal release control, and to prevent the misfiring by reducing the deterioration of the combustion state during the abnormal release control. Drivability and exhaust emissions can be improved, and engine stall can be prevented.

In the system provided with the exhaust gas recirculation device, when it is determined that the lock is not released after the end of the lock release control, the lock release of the lock mechanism is detected by the re-release control. Until
Control may be performed so as to reduce the exhaust recirculation flow rate (external EGR amount) by the exhaust recirculation device. In other words, the effects of the internal EGR and the external EGR on the combustibility are the same,
Since the sum of the R amount and the external EGR amount is the total EGR amount,
Even if the internal EGR amount increases during the abnormality release control, if the external EGR amount is reduced, the increase in the total EGR amount can be suppressed, and the deterioration of the combustion state during the abnormality release control can be prevented.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment (1)] An embodiment (1) in which the present invention is applied to an intake valve variable valve timing control apparatus will be described below with reference to FIGS. As shown in FIG. 1, in a DOHC engine 11 which is an internal combustion engine, power from a crankshaft 12 is transmitted to an intake side camshaft 16 and an exhaust side camshaft 17 by timing chains 13 via respective sprockets 14 and 15. It has become so. However, the intake camshaft 16 is provided with a variable valve timing device 18 for adjusting the advance amount of the intake camshaft 16 with respect to the crankshaft 12.

A cam angle sensor 19 for outputting a cam angle signal at a plurality of cam angles for cylinder discrimination is provided on the outer peripheral side of the intake side camshaft 16, while on the outer peripheral side of the crankshaft 12. A crank angle sensor 20 for outputting a crank angle signal at every predetermined crank angle is provided. The output signals of the cam angle sensor 19 and the crank angle sensor 20 are input to an engine control circuit 21, which calculates the actual valve timing of the intake valve and the frequency of the output pulse of the crank angle sensor 20. Is used to calculate the engine speed. Various sensors (intake pressure sensor 2
2, an output signal of the water temperature sensor 23, the throttle sensor 24, etc.) is input to the engine control circuit 21.

The engine control circuit 21 performs fuel injection control and ignition control based on these various input signals, performs variable valve timing control, and performs actual valve timing of the intake valve (actual travel of the intake camshaft 16). The variable valve timing device 18 is feedback-controlled so that the angle amount coincides with the target valve timing (target advance amount). The oil in the oil pan 27 is supplied to the oil pump 28 by the hydraulic control circuit of the variable valve timing device 18.
Thus, the actual valve timing of the intake valve is controlled by controlling the hydraulic pressure by the hydraulic control valve 29.

Next, the configuration of the variable valve timing device 18 with an intermediate lock mechanism will be described with reference to FIGS. Housing 31 of variable valve timing device 18
Is fastened by bolts 32 to a sprocket 14 rotatably supported on the outer periphery of the intake side camshaft 16. As a result, the rotation of the crankshaft 12 is controlled by the sprocket 14 and the housing 31 via the timing chain 13.
The sprocket 14 and the housing 31 rotate in synchronization with the crankshaft 12.

On the other hand, the intake side camshaft 16 is rotatably supported by a cylinder head 33 and a bearing cap 34, and a rotor 35 is fastened to one end of the intake side camshaft 16 by a bolt 37 via a stopper 36. Have been. The rotor 35 is housed in the housing 31 so as to be relatively rotatable.

As shown in FIG. 3 and FIG.
A plurality of fluid chambers 40 are formed inside 1, and each fluid chamber 40 is partitioned into an advance chamber 42 and a retard chamber 43 by a vane 41 formed on the outer periphery of the rotor 35. And, on the outer peripheral portion of the rotor 35 and the outer peripheral portion of the vane 41,
Each of the seal members 44 is attached,
Are urged in the outer peripheral direction by a leaf spring 45 (see FIG. 2). Thereby, the gap between the outer peripheral surface of the rotor 35 and the inner peripheral surface of the housing 31 and the gap between the outer peripheral surface of the vane 41 and the inner peripheral surface of the fluid chamber 40 are sealed by the seal member 44.

As shown in FIG. 2, annular advance grooves 46 and retard grooves 47 formed on the outer periphery of the intake camshaft 16 are connected to predetermined ports of the hydraulic control valve 29, respectively. When the oil pump 28 is driven by power, the oil pumped from the oil pan 27 is supplied to the advance groove 46 and the retard groove 47 via the hydraulic control valve 29. The advance oil passage 48 connected to the advance groove 46 is connected to the intake camshaft 1.
6 is formed so as to communicate with an arc-shaped advance oil passage 49 (see FIG. 3) formed on the left side surface of the rotor 35 through the interior of the rotor 6. Is in communication with On the other hand, the retard oil passage 50 connected to the retard groove 47 is
The arc-shaped retarded oil passage 51 is formed so as to penetrate through the inside of the intake-side camshaft 16 and communicate with an arc-shaped retarded oil passage 51 (see FIG. 4) formed on the right side surface of the rotor 35. It communicates with the retard chamber 43.

The hydraulic control valve 29 is a four-port, three-position switching valve that drives a valve body with a solenoid 53 and a spring 54. The valve body position is determined by a position for supplying hydraulic pressure to the advance chamber 42 and a retard chamber. The position is switched between a position where oil pressure is supplied to 43 and a position where oil pressure is not supplied to both the advance chamber 42 and the retard chamber 43. When the power supply to the solenoid 53 is stopped, the valve body is automatically switched to a position for supplying hydraulic pressure to the advance chamber 42 by the spring 54, and hydraulic pressure acts in a direction for advancing the camshaft phase. A valve stroke sensor 25 (see FIG. 1) for detecting the stroke of the valve body of the hydraulic control valve 29 is provided, and an output signal of the valve stroke sensor 25 is input to the engine control circuit 21.

In a state in which a hydraulic pressure of a predetermined pressure or more is supplied to the advance chamber 42 and the retard chamber 43, the vane 41 is fixed by the hydraulic pressure of the advance chamber 42 and the retard chamber 43, and the rotation of the crankshaft 12 The rotation of the housing 31 causes the rotation of the rotor 35 via oil.
(The vane 41), and the intake-side camshaft 16 is rotationally driven integrally with the rotor 35. During operation of the engine, the hydraulic pressure in the advance chamber 42 and the retard chamber 43 is controlled by the hydraulic control valve 29 to relatively rotate the housing 31 and the rotor 35 (vane 41), so that the intake-side cam with respect to the crankshaft 12. The rotation timing of the shaft 16 (hereinafter referred to as “camshaft phase”) is controlled to vary the valve timing of the intake valve. The sprocket 14 accommodates a torsion coil spring 55 (see FIG. 2) that assists the hydraulic pressure for relatively rotating the rotor 35 in the advance direction during the advance control by a spring force.

As shown in FIGS. 3 and 4, stopper portions 56 are formed on both sides of one of the vanes 41 to regulate the relative rotation range of the rotor 35 (vane 41) with respect to the housing 31. The stopper portion 56 regulates the most retarded phase and the most advanced phase of the camshaft phase. Further, the lock pin receiving hole 57 formed in the other vane 41 has the housing 31 and the rotor 35 (the vane 4).
A lock pin 58 for locking relative rotation with 1) is housed, and the lock pin 58 is fitted into a lock hole 59 (see FIG. 2) provided in the housing 31 to adjust the camshaft phase. Locked at a substantially intermediate position (intermediate lock position) of the possible range. This intermediate lock position is set to a position suitable for starting.

As shown in FIGS. 6 and 7, the lock pin 5
8 is slidably inserted into a cylindrical member 61 fitted on the inner periphery of the lock pin receiving hole 57, and is urged by a spring 62 in the lock direction (projection direction). Further, a gap between the cylindrical member 61 and the lock pin 58 is partitioned into a lock hydraulic chamber 64 and a lock release hydraulic chamber 65 by a valve portion 63 formed at a central outer peripheral portion of the lock pin 58. In order to supply hydraulic pressure from the advance chamber 42 to the lock hydraulic chamber 64 and the lock release hold hydraulic chamber 65, the vane 41 has a lock oil passage 66 communicating with the advance chamber 42 and a lock release hold An oil passage 67 is formed.
The housing 31 has a lock hole 59 and a retard chamber 43.
And a lock release oil passage 68 is formed.

As shown in FIG. 6, when the lock pin 58 is locked, the valve portion 63 of the lock pin 58 closes the oil passage 67 for releasing and holding the lock, and the lock oil passage 66 communicates with the lock hydraulic chamber 64. State. Thereby, the advance chamber 42
The lock hydraulic chamber 64 is supplied with a hydraulic pressure, and the lock pin 58 is held in the lock hole 59 by the hydraulic pressure and the spring 62 so that the camshaft phase is locked at the intermediate lock position.

While the engine is stopped, the hydraulic pressure in the lock hydraulic chamber 64 (the hydraulic pressure in the advance chamber 42) decreases.
As a result, the lock pin 58 is held at the lock position. Therefore, the engine is started in a state where the lock pin 58 is held at the lock position (intermediate lock position), and the lock release control is performed when the discharge pressure of the oil pump 28 increases to some extent after the engine is started. By this lock release control, the hydraulic pressure of the lock hole 59 (the hydraulic pressure of the retard chamber 43)
Is increased, the lock of the lock pin 58 is released by the hydraulic pressure as follows. By the lock release control after the engine is started, the lock release oil passage 68
The hydraulic pressure (force in the unlocking direction) supplied to the lock hole 59 through the hole is larger than the combined force (force in the locking direction) of the hydraulic pressure of the lock hydraulic chamber 64 (the hydraulic pressure of the advance chamber 42) and the spring force of the spring 62. Then, the lock pin 58 is pushed out of the lock hole 59 by the hydraulic pressure of the lock hole 59 and moves to the lock release position in FIG. 7, and the lock of the lock pin 58 is released.

In this unlocked state, as shown in FIG. 7, the valve portion 63 of the lock pin 58 closes the lock oil passage 66, and the lock release holding oil passage 67 is connected to the lock release holding hydraulic chamber 65. It will be in the state of communication. Accordingly, the hydraulic pressure is supplied from the advance chamber 42 to the hydraulic chamber 65 for holding and releasing the lock, and the hydraulic pressure of the hydraulic chamber 65 for holding and releasing the lock (the hydraulic pressure of the advance chamber 42) and the hydraulic pressure of the lock hole 59 (the retard angle). The lock pin 58 is held at the unlocked position against the spring 62 by the pressure of the chamber 43).

During operation of the engine, the advance chamber 42 and the retard chamber 4
3, the lock pin 58 is held at the unlocked position by the hydraulic pressure, and the housing 31 and the rotor 35 can be relatively rotated (that is, the valve timing can be controlled). Is held.

During operation of the engine, the engine control circuit 21
Calculates the actual valve timing of the intake valve (the actual advance angle position of the intake-side camshaft 16) based on the output signals of the crank angle sensor 20 and the cam angle sensor 19, and calculates the intake pressure sensor 22, the water temperature sensor 23, etc. The target valve timing of the intake valve (the target advance position of the intake camshaft 17) is calculated based on the outputs of various sensors that detect the engine operating state. Then, the hydraulic control valve 29 of the variable valve timing device 18 is feedback-controlled so that the actual valve timing of the intake valve matches the target valve timing. Thus, by controlling the oil pressure in the advance chamber 42 and the retard chamber 43 to relatively rotate the housing 31 and the rotor 35, the camshaft phase is changed, and the actual valve timing of the intake valve is set to the target valve timing. Match.

Thereafter, when the engine 11 is stopped,
When the engine rotation speed decreases, the discharge pressure of the oil pump 28 decreases, so that the hydraulic pressure of the advance chamber 42 and the retard chamber 43 decreases. As a result, the hydraulic pressure of the lock release holding hydraulic chamber 65 (the hydraulic pressure of the advance chamber 42) and the hydraulic pressure of the lock hole 59 (the hydraulic pressure of the retard chamber 43) are reduced, and the spring force of the spring 62 is reduced to these hydraulic pressures. When it overcomes, the lock pin 58 projects by the spring force of the spring 62 and fits into the lock hole 59. However, lock pin 5
In order for 8 to fit into the lock hole 59, the two positions must match, that is, the camshaft phase must match the intermediate lock position.

When the engine 11 is stopped, the engine rotation speed (the rotation speed of the oil pump 28) is reduced and the oil pressure is reduced. Therefore, the camshaft phase is naturally retarded by the load torque of the camshaft 16. In the process, as shown in FIG. 6, the lock pin 58 is fitted into the lock hole 59 to lock the camshaft phase at the intermediate lock position.

As described above, the engine is started with the lock pin 58 held at the lock position (intermediate lock position). When the discharge pressure of the oil pump 28 rises to some extent after the engine is started, the lock is started. Release control is performed. When the hydraulic pressure of the lock hole 59 (the hydraulic pressure of the retard chamber 43) is increased by this lock release control, the lock of the lock pin 58 is released by the hydraulic pressure, and the valve release (camshaft phase) of the intake valve is released by this lock release. Is in a state where the feedback control can be executed.

However, even if the lock release control is performed, the lock of the lock pin 58 may not be released for some reason. If the lock cannot be released, the lock release control may be performed again. In this way, if the lock mechanism is temporarily unlocked due to a foreign object being caught in the lock mechanism or the like, the lock may be unlocked again by unlock control again. In addition to the failure, the operation failure of the hydraulic control valve 29 is considered. In the case of malfunction of the hydraulic control valve 29, even if the lock control signal is output to the hydraulic control valve 29, the hydraulic control valve 29 does not operate normally. I can't.

Therefore, in the present embodiment (1), the engine control circuit 21 executes the lock release program shown in FIG. 8 stored in the built-in ROM (storage medium) to release the lock after the lock release control is completed. If it is determined that there is no such condition, the hydraulic control valve 29 is driven by the drive pattern of the abnormality release control (see FIG. 9) to remove the cause of the malfunction (foreign matter or the like) and then perform the lock release control again. This program is started after an ignition switch (not shown) is turned on, and plays a role as a lock release control means referred to in the claims.

When the present program is started, first, at step 101, the process waits until the lock release control ends after the engine is started. Thereafter, when the lock release control ends, the process proceeds to step 102, and it is determined whether or not the lock has been released (that is, whether or not the lock pin 58 has come out of the lock hole 59) as follows. First, it is determined whether or not the current actual advance position (actual valve timing) VT is within a predetermined range (VTA <VT <VTB) near the intermediate lock position. Here, a predetermined range (VTA <VT <VT)
B) is set within a range from the intermediate lock position to a predetermined value (for example, a value in which an error factor such as a detection error of the actual advance position VT, a manufacturing variation, and a change with time) is maximally estimated. If the current actual advance position VT is not within a predetermined range near the intermediate lock position, it is apparent that the camshaft phase is far from the intermediate lock position even when error factors such as detection errors are considered as much as possible. Therefore, it is determined that the lock is released.

On the other hand, if the current actual advance position VT is within a predetermined range near the intermediate lock position, it is determined whether or not the lock has been released based on the degree of variation in the advance amount of the cam angle signal. In other words, when the lock is released, the camshaft phase slightly vibrates even if the camshaft phase is controlled near the intermediate lock position by hydraulic pressure, so that the degree of variation in the advance amount of the cam angle signal increases. Using this characteristic, it is determined whether or not the lock is released based on the degree of variation in the advance amount of the cam angle signal. Note that the process of step 102 plays a role as a lock release determination unit referred to in the claims.

If it is determined in step 102 that the lock has been released, the program is terminated. If the lock has not been released, the routine proceeds to step 103, where abnormality control of the hydraulic control valve 29 is executed. In this abnormality release control, as shown in FIG. 9, the applied current of the hydraulic control valve 29 is alternately switched between, for example, 100 mA and 1000 mA in a constant cycle, so that the valve stroke of the hydraulic control valve 29 is changed from 0 to a full stroke. The operation of reciprocating between them is repeated for a predetermined time. With this configuration, in the case of a temporary malfunction due to foreign matter being caught in the hydraulic control valve 29, etc., while repeating the operation of reciprocating the valve body of the hydraulic control valve 29 by full stroke by the abnormality release control, The cause of the malfunction (foreign matter, etc.) is removed, and the hydraulic control valve 29 returns to a state where it can operate normally.

During the abnormality release control, it is determined whether or not the hydraulic control valve 29 operates normally based on the output signal of the valve stroke sensor 25 for detecting the stroke of the valve body of the hydraulic control valve 29 (step 104). If the hydraulic control valve 29 does not operate normally by the time the abnormal release control ends, it is determined that the hydraulic control valve 29 is malfunctioning (step 105). If the operation of the hydraulic control valve 29 is defective, even if the lock release control is performed again, it is useless, so the program is terminated. If it is determined that the operation of the hydraulic control valve 29 is defective, the information is stored in a nonvolatile memory (backup RAM).
And the like, and informs the driver of the abnormality by lighting a warning lamp or the like, and further controls the fuel injection amount, ignition timing, and the like so that the engine 11 can be operated with the variable valve timing device 18 locked.

On the other hand, if the hydraulic control valve 29 operates normally by the end of the abnormality release control, the routine proceeds to step 106,
The lock release control is executed again. At this time, if the lock mechanism is normal, the lock can be released by the lock release control again. Thereafter, the process proceeds to step 107, where it is determined whether or not the lock has been unlocked in the same manner as in step 102. If the lock has been unlocked, the program ends. If the lock has not been released, the process proceeds to step 108, where it is determined that the lock pin 58 is not properly unlocked (locked). That is, since it is confirmed in step 104 that the hydraulic control valve 29 operates normally, if the lock is not released even if the lock release control is performed again, the lock pin 58 may not be properly unlocked (lock lock failure). ) Can be determined.
If it is determined that the lock pin 58 is not properly unlocked, the information is stored in a nonvolatile memory (backup RAM).
And the like, and informs the driver of the abnormality by lighting a warning lamp or the like, and further controls the fuel injection amount, ignition timing, and the like so that the engine 11 can be operated with the variable valve timing device 18 locked.

An execution example of the above-described lock release program shown in FIG. 8 will be described with reference to a time chart shown in FIG.
FIG. 10 is an example of control in a case where a lock release failure (lock lock) of the lock pin 58 has occurred. in this case,
Even if you perform unlock control, you cannot unlock.
After the abnormality release control of the hydraulic control valve 29 is performed, the lock release control is performed again. If the lock is not released even if the lock release control is performed again, it is determined that the lock pin 58 is not properly unlocked (lock lock).

In the embodiment (1) described above, the hydraulic control valve 29 is driven by the drive pattern of the abnormal release control before performing the lock release control again.
In the case of a temporary malfunction due to a foreign object being caught in the device, the lock release control can be performed again after the hydraulic control valve 29 is returned to a state in which the hydraulic control valve 29 can be normally operated by the abnormality release control. For this reason, if the lock mechanism is normal, the lock can be unlocked by the unlock control again, and the occurrence rate of the unlock failure can be reduced as compared with the conventional case.
The reliability of the variable valve timing control can be improved.

Further, in this embodiment (1), the stroke of the valve body of the hydraulic control valve 29 is detected by the valve stroke sensor 25 during the abnormality release control, and it is determined whether or not the hydraulic control valve 29 operates normally. Because the judgment was made, the cause of the unlock failure was the malfunction of the lock mechanism (lock lock).
And the malfunction of the hydraulic control valve 29 can be specified. By storing this information in a non-volatile memory (backup RAM or the like), it is possible to easily perform a failure diagnosis at the time of failure repair. it can.

In this embodiment (1), it is determined whether or not the hydraulic control valve 29 is malfunctioning before performing the lock release control again. However, the end of the lock release control again. If it is later determined that the lock release is defective, the power main relay is on (power is on) after the engine is stopped.
Alternatively, abnormality release control of the hydraulic control valve 29 may be performed to determine whether or not the operation of the hydraulic control valve 29 is defective.

The sensor for detecting the operating state of the valve body of the hydraulic control valve 29 is not limited to one valve stroke sensor 25. For example, the position where the valve stroke of the hydraulic control valve 29 is 0 and the position of the full stroke A sensor for detecting the valve body may be installed at each position, and the operating state of the valve body of the hydraulic control valve 29 may be detected by two sensors.

The present invention also relates to a valve stroke sensor 25
May be omitted and the malfunction of the hydraulic control valve 29 may not be detected. In this case, the intended object of the present invention can be sufficiently achieved.

Further, in the present embodiment (1), the hydraulic control valve 29 is driven with a full stroke during the abnormality release control. However, the hydraulic control valve 29 may be driven with a smaller stroke than the full stroke. Further, in the present embodiment (1), the hydraulic control valve 29 is driven at a constant stroke during the abnormality release control. However, the drive stroke of the hydraulic control valve 29 is gradually increased during the abnormality release control. The drive stroke may be gradually changed.

It should be noted that the hydraulic control valve 2
If it is determined that the operation is abnormal, the abnormality release control may be repeated again. When the operation of the hydraulic control valve 29 is determined to be normal, the lock release control may be repeated once or twice or more if the lock cannot be released again by the lock release control.

[Embodiment (2)] The above embodiment (1)
Is an embodiment in which the variable valve timing device 18 is provided only for the intake valve, but the embodiment (2) of the present invention shown in FIGS. 11 and 12 employs the variable valve timing device for both the intake valve and the exhaust valve. It is an embodiment provided.
Also in this embodiment (2), the variable valve timing device on the intake side has the same configuration as the variable valve timing device 18 with the intermediate lock mechanism of the above-described embodiment (1).
The variable valve timing device on the exhaust side has the same configuration as a conventional variable valve timing device without an intermediate lock mechanism. Since the exhaust valve timing at the time of starting the engine is the most advanced phase, when the variable valve timing control is started, the exhaust valve timing is controlled to the retard side (see FIG. 12).

In this configuration, when the variable valve timing control is performed in a state where the lock of the variable valve timing device on the intake side is not released, only the variable valve timing device on the exhaust side normally operates. There is a possibility that the overlap amount or the like becomes abnormal and the residual ratio of exhaust gas (internal EGR amount) in the cylinder becomes excessive. As a result, the combustion state in the cylinder deteriorates and misfiring occurs. Exhaust emissions deteriorate and, in the worst case, may lead to engine stall.

Therefore, in this embodiment (2), the exhaust valve timing is controlled so as to suppress the increase in the residual ratio of exhaust gas (internal EGR amount) in the cylinder until the unlock is detected by the unlock program of FIG. Control. FIG.
This program is obtained by adding the processing of steps 102a and 109 to the program of FIG. 8 described in the embodiment (1).

In the present program, if it is determined that the lock is not released after the end of the lock release control, step 1 is executed.
02a, the advance of the exhaust valve timing is corrected,
By reducing the valve overlap amount of the intake and exhaust valves, the internal EGR amount of the engine during the abnormality release control is reduced, and deterioration of the combustion state is suppressed. Incidentally, the advance correction of the exhaust valve timing may be controlled so as to be the most advanced phase, or the exhaust valve timing may be advanced by a predetermined correction amount α than usual. This correction amount α
May be changed by a map or the like according to the engine operating state, and may of course be a fixed value.

Thereafter, the abnormality release control and the lock release control are performed again. If the lock is released, the routine proceeds to step 109, where the exhaust valve timing control is returned to the normal control. If the lock is not released, the advance correction of the exhaust valve timing is continued thereafter, and the engine is operated with the internal EGR amount reduced. As a result, it is possible to prevent the misfiring by preventing the deterioration of the combustion state of the engine at the time of the unlocking failure, to improve the drivability and the exhaust emission, and to prevent the engine stall.

In this embodiment (2), the advance of the exhaust valve timing is corrected during the abnormality release control. However, the exhaust valve timing control is stopped during the abnormality release control to fix the exhaust valve timing. You may do it. Also in this case, it is possible to suppress an increase in the internal EGR amount during the abnormality release control, and it is possible to reduce deterioration of the combustion state.

[Other Embodiments] The above embodiment (2)
When the present invention is applied to a system in which an exhaust gas recirculation device (EGR device) is added to the configuration of the above, when it is determined that the lock is not released after the end of the lock release control, the exhaust valve timing is advanced and the internal EGR is corrected. Correct the amount by weight reduction,
In addition, the external EGR amount by the exhaust gas recirculation device may be corrected to be reduced, or only the external EGR amount may be corrected to be corrected without performing the advance angle correction of the exhaust valve timing. That is, both the internal EGR and the external EGR have the same effect on the combustibility, and the sum of the internal EGR amount and the external EGR amount is the total EGR amount. Therefore, even if the internal EGR amount increases during the abnormality release control, If the external EGR amount is reduced, an increase in the total EGR amount can be suppressed, and deterioration of the combustion state of the engine can be prevented.

In the present invention, the lock mechanism may be provided in the variable valve timing device on the exhaust side. Of course, the lock mechanisms may be provided in both the variable valve timing devices on the intake side and the exhaust side. In this case, when it is determined that the lock is not unlocked after the lock release control of the lock mechanism of the exhaust-side variable valve timing device is completed, the intake valve timing is retarded so as to reduce the internal EGR amount, or The degree of opening of the EGR valve may be controlled so as to reduce the external EGR amount.

The locking mechanism of the variable valve timing device is not limited to the locking mechanism at the intermediate locking position, but may be configured to lock at a position other than the intermediate locking position (eg, the most retarded position or the most advanced position). The present invention can also be applied and implemented.

In addition, the present invention can be implemented with various changes without departing from the gist, such as by appropriately changing the structure of the variable valve timing device and the structure of the lock mechanism.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire control system showing an embodiment (1) of the present invention.

FIG. 2 is a longitudinal sectional view of a variable valve timing device.

FIG. 3 is a sectional view taken along the line AA of FIG. 2;

FIG. 4 is a sectional view taken along line BB in FIG. 2;

FIG. 5 is a sectional view taken along the line CC of FIG. 4;

FIG. 6 is a partially enlarged sectional view showing a locked state of a lock pin.

FIG. 7 is a partially enlarged cross-sectional view showing an unlocked state of a lock pin.

FIG. 8 is a flowchart showing the flow of processing of an unlocking program according to the embodiment (1).

FIG. 9 is a time chart showing a drive pattern of abnormality release control;

FIG. 10 is a time chart showing an example of unlock control according to the embodiment (1).

FIG. 11 is a flowchart showing the flow of processing of an unlocking program according to the embodiment (2).

FIG. 12 is a diagram showing opening / closing timing characteristics of an intake valve and an exhaust valve.

[Explanation of symbols]

11 ... engine (internal combustion engine), 12 ... crankshaft, 13
... Timing chains, 14, 15 ... Sprockets, 1
6 ... intake cam shaft, 17 ... exhaust cam shaft, 18 ... variable valve timing device, 19 ... cam angle sensor, 20 ... crank angle sensor, 21 ... engine control circuit (lock release determination means, lock release control means), 25 ... Valve stroke sensor, 28 oil pump, 29 hydraulic control valve, 31 housing, 35 rotor, 40 fluid chamber, 41 vane, 42 advance chamber, 43 retard chamber, 53 solenoid
54 ... spring, 58 ... lock pin (lock mechanism),
59: lock hole (lock mechanism), 62: spring (lock mechanism).

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 3G016 AA08 AA19 BA23 BA28 CA21 CA24 CA27 CA36 CA48 DA06 DA23 DA25 GA00 3G092 AA11 AA17 BA09 BB01 DA01 DA02 DA09 DC09 DF04 DF06 DG02 DG05 EA02 EA03 EA09 EA13 EA15 FA03 FA40 FB03 FB05 FB06 GA01 GA10 HA05Z HA06Z HA13X HA13Z HB01X HC09X HD09X HE01Z HE03Z HE08Z HF19Z

Claims (5)

[Claims] At least one of an intake valve and an exhaust valve of an internal combustion engine is provided with a variable valve timing device for varying valve timing, and the variable valve timing device sets a valve timing when variable valve timing control is not performed. A variable valve timing control device for an internal combustion engine, wherein a lock mechanism that locks in phase is provided, and the lock mechanism and the variable valve timing device are driven by a hydraulic control circuit. A lock release control unit that controls a hydraulic control valve of the hydraulic control circuit so as to apply a lock release direction, and a lock release determination unit that determines whether or not the lock mechanism is unlocked. Must be unlocked after the unlock control ends A variable valve timing control device for an internal combustion engine, wherein the lock release control is performed again after the hydraulic control valve is driven in the drive pattern of the abnormality release control when the determination is made. 2. The variable valve timing control apparatus for an internal combustion engine according to claim 1, wherein in the abnormality release control, an operation of reciprocating a valve body of the hydraulic control valve at a predetermined stroke is repeated. 3. The lock release control means releases the lock due to a malfunction of the lock mechanism if the valve body of the hydraulic control valve operates normally when the hydraulic control valve is driven in the drive pattern of the abnormal release control. The variable valve timing control device for an internal combustion engine according to claim 1, wherein the variable valve timing control device is determined to be defective. 4. The variable valve timing device is provided on each of an intake valve and an exhaust valve of an internal combustion engine, the lock mechanism is provided on at least one of the variable valve timing devices, and the lock release control means is configured to release the lock. When it is determined that the lock has not been released after the control has been completed, the variable valve timing control of the normally operating variable valve timing device is stopped or performed until the lock release of the lock mechanism is detected by the re-release control. 4. The variable valve timing control apparatus for an internal combustion engine according to claim 1, wherein the control is performed such that a residual ratio of exhaust gas in a cylinder of the internal combustion engine is reduced. 5. An exhaust gas recirculation device for recirculating a part of exhaust gas of an internal combustion engine to an intake system, wherein the lock release control means locks again when it is determined that the lock is not released after the lock release control is completed. The variable internal combustion engine according to any one of claims 1 to 4, wherein control is performed so as to reduce an exhaust recirculation flow rate by the exhaust recirculation device until unlocking of the lock mechanism is detected by release control. Valve timing control device.