JP2002266669A - Variable valve timing control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely advance and lock a camshaft phase to a lock position at the time of stopping an engine in a variable valve timing device equipped with intermediate lock mechanism. SOLUTION: When the engine stop is instructed, an ISC valve is fully opened to increase the intake air quantity. Since the negative torque generated by the compression of intake air in compression stroke is increased up to the perfect stop of the engine, a crankshaft is slightly pushed back in a reverse rotating direction by this large negative torque at a moment the normal directional rotation of the crankshaft is stopped. Accordingly, the camshaft phase can be advanced to the lock position by the reverse rotation of the crankshaft if the camshaft phase is not locked until the crankshaft is reversely rotated, and the camshaft phase can be locked in the lock position. Otherwise, a hydraulic advance control of camshaft phase may be executed while executing this intake air increasing control in the engine stop.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine which locks a rotation phase of a camshaft with respect to a crankshaft (hereinafter referred to as "camshaft phase") at a substantially middle lock position of an adjustable range when the internal combustion engine is started. The present invention relates to a variable valve timing control device.

[0002]

2. Description of the Related Art In recent years, an internal combustion engine mounted on a vehicle is increasingly employing a variable valve timing control device for the purpose of improving output, reducing fuel consumption and reducing exhaust emissions. For example, a general configuration of a vane type variable valve timing control device is disclosed in
As shown in Japanese Patent No. 10424 (see FIG. 8), a housing 1 that rotates in synchronization with a crankshaft of an engine and a rotor 2 connected to a camshaft of an intake (or exhaust) valve are coaxially arranged. The fluid chamber 3 formed in the housing 1 is partitioned into an advance chamber 5 and a retard chamber 6 by vanes 4 provided on the rotor 2. The hydraulic pressure in the advance chamber 5 and the retard chamber 6 is controlled by a hydraulic control valve to control the housing 1 and the rotor 2 (vane 4).
Are relatively rotated to change the rotational phase of the camshaft with respect to the crankshaft (camshaft phase) to variably control the valve timing.

In this vane type variable valve timing control device, the relative rotation between the housing 1 and the rotor 2 (vane 4) when the engine is stopped is performed in order to prevent noise caused by the vibration of the vane 4 at the time of starting (when the hydraulic pressure is lowered). The operation is locked by a lock pin 7, and the engine is started in this locked state.

Conventionally, the lock position (starting phase) is set to the most retarded phase. In this configuration, the camshaft phase (valve timing) is delayed from the starting phase during engine operation. Since it cannot be controlled to the corner side, there is a disadvantage that the adjustable range of the camshaft phase is narrow.

Therefore, in the above publication, the camshaft phase is set during the engine operation by setting the lock position (the phase at the start) to a substantially intermediate position of the adjustable range of the camshaft phase. The lock position can be adjusted in both the advance side and the retard side.

The lock pin 7, which locks the camshaft phase at the lock position, is urged in the lock direction by a spring, and is held at the unlock position by hydraulic pressure during engine operation. This oil pressure is boosted by an oil pump driven by the power of the engine, so when the engine stops,
When the engine rotation speed (oil pump rotation speed) decreases and the oil pressure decreases, the lock pin 7 is fitted into the lock hole by the spring, and the camshaft phase is locked at the lock position. However, in order for the lock pin 7 to fit into the lock hole, it is necessary that both positions match.

When the oil pressure drops when the engine stops, the camshaft phase naturally changes to the retard side due to the load torque of the camshaft, so that the camshaft phase advances from the lock position immediately before the engine stops. If it is controlled to the corner side, the camshaft phase can be locked at the lock position when the camshaft phase changes to the retard side and reaches the lock position. However, if the camshaft phase is controlled to be more retarded than the lock position immediately before the engine stops, the camshaft phase is locked even if the camshaft phase changes to the retarded side due to a decrease in oil pressure when the engine is stopped. Since it does not reach the position, the camshaft phase cannot be locked at the lock position.

Therefore, in the above-mentioned publication, when the engine is stopped, the hydraulic control valve is controlled so as to advance the camshaft phase by making maximum use of the remaining oil pressure until the engine rotation is stopped. Has been proposed.

[0009]

However, a state in which the engine load is relatively large (for example, a state in which the shift position of the automatic transmission is shifted to a power transmission position such as a D range).
When the ignition switch is turned off, the engine speed drops sharply and the oil pressure drops sharply compared to when the engine is stopped, so the time during which the camshaft phase can be advanced by the oil pressure becomes very short. In some cases, the camshaft phase cannot be advanced to the lock position and locked.
If the camshaft phase cannot be locked at the lock position when the engine is stopped, the valve timing (camshaft phase) will be the target at the next start until the engine speed (oil pump speed) increases and the oil pressure rises. It cannot be controlled to a value (near the lock position). As a result, the engine is started at a valve timing that deviates from the target value, so that the startability deteriorates and the engine start time becomes longer. In addition, if the engine is started without locking the camshaft phase, the position of the vane 4 is not fixed until the hydraulic pressure rises, so that there is a problem that the vane 4 collides with the housing 1 to generate noise.

As a countermeasure, it is conceivable that the camshaft phase is controlled in the vicinity of the lock position in advance during the idle operation before the engine is stopped. However, during idle operation before the engine is stopped, the valve timing of the intake valve (camshaft) is controlled. Phase) to the starting phase (lock position),
The amount of valve overlap increases, the combustion state deteriorates, and the exhaust emission may deteriorate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a mechanism for locking a camshaft phase at a lock position substantially in the middle of an adjustable range when an internal combustion engine is stopped. The variable valve timing of the internal combustion engine, which can securely advance the camshaft phase to the lock position when the internal combustion engine is stopped, and can also prevent deterioration of exhaust emission It is to provide a control device.

[0012]

According to a first aspect of the present invention, there is provided a variable valve timing control apparatus for an internal combustion engine according to the first aspect of the present invention.
The intake air increase control means performs control to increase the intake air amount (hereinafter referred to as “intake air increase control”).

When a stop command for the internal combustion engine is issued and the combustion (fuel injection or ignition) is stopped, the rotation of the internal combustion engine (the rotation of the crankshaft) is reduced and stopped. At this time, as shown in FIG. 6, until the rotation of the internal combustion engine is completely stopped, even after the combustion is stopped, the compression and expansion of the intake air is performed by the piston in the compression stroke and the expansion stroke of each cylinder. In the compression stroke, torque in the reverse rotation direction (negative torque) is generated, and in the expansion stroke, torque in the positive rotation direction (positive torque) is generated. However, after the combustion is stopped, the positive torque generated in the expansion stroke becomes smaller. Negative torque becomes relatively larger than positive torque,
The brake is applied to the rotation of the crankshaft, and the rotation of the crankshaft decreases and stops.

In the present invention, since the intake air amount is increased after the stop command of the internal combustion engine, the negative torque generated by the compression of the intake air in the compression stroke increases as shown by the broken line in FIG. For this reason, at the moment when the rotation of the crankshaft in the forward rotation direction is stopped, the crankshaft is slightly pushed back in the reverse rotation direction by this large negative torque and then stopped. By this time, the oil pressure in the variable valve timing device has dropped so much that the camshaft phase can no longer be fixed by oil pressure, so even if the crankshaft (vane) rotates a little backward,
The reverse rotation is hardly transmitted to the housing (camshaft) of the variable valve timing device. For this reason, only the crankshaft (vane) rotates a little in the reverse direction with the housing (camshaft) of the variable valve timing device almost stopped, whereby the camshaft phase with respect to the crankshaft is advanced relatively. You. Thus, when the internal combustion engine is stopped, the camshaft phase can be reliably advanced to the lock position by the intake air increase control, and the camshaft phase can be reliably locked at the lock position. Moreover, it is not necessary to previously control the camshaft phase near the lock position (starting phase) during the idling operation before the internal combustion engine stops, so that deterioration of exhaust emission can be avoided.

Generally, an engine control system is often provided with a bypass air amount adjusting valve, such as an idle speed control valve, for adjusting the amount of intake air that bypasses a throttle valve in order to control idle rotation. In the system having such a bypass air amount adjusting valve, the intake air increasing control is performed by opening the bypass air amount adjusting valve when a stop command of the internal combustion engine is issued, as in claim 2. It is better to do it. With this configuration, when a stop command for the internal combustion engine is issued, the camshaft phase can be reliably locked at the lock position by the valve opening control of the bypass air amount adjustment valve.

Further, in an electronic throttle system for driving a throttle valve by a motor or a system having a throttle opener mechanism for opening a throttle valve by a diaphragm actuator or the like when the internal combustion engine is stopped, the internal combustion engine according to a third aspect of the present invention. When an engine stop command is issued, the intake air increase control may be performed by opening the throttle valve. Even if you do this,
The camshaft phase can be reliably locked at the lock position by using the existing system.

Further, the hydraulic control valve may be controlled so as to advance the camshaft phase when a stop command for the internal combustion engine is issued. With this configuration, when the internal combustion engine is stopped, the camshaft phase is advanced by the hydraulic pressure while the hydraulic pressure remains to some extent. And, even if the camshaft phase cannot be advanced to the lock position by the hydraulic advance control, at the moment when the rotation of the crankshaft in the forward rotation direction is stopped,
Due to the increase in negative torque due to the increase in intake air, the crankshaft is slightly reversely rotated to relatively advance the camshaft phase,
The camshaft phase is locked at the lock position. in this way,
If the intake air increase control and the hydraulic advance control are combined, the camshaft phase can be locked more reliably.

[0018]

FIG. 1 shows an embodiment in which the present invention is applied to a variable valve timing control device for an intake valve.
7 through FIG. First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of an intake pipe 12 of an engine 11 which is an internal combustion engine, and an air flow meter 14 for detecting an intake air amount is provided downstream of the air cleaner 13.
Is provided. Downstream of the air flow meter 14, a throttle valve 15 and a throttle opening sensor 16 for detecting a throttle opening are provided. The intake pipe 12 is provided with a bypass passage 23 that bypasses the throttle valve 15.
3, an idle speed control valve (ISC valve) 24 is provided as a bypass air amount adjusting valve for adjusting the amount of intake air that bypasses the throttle valve 15.

Further, on the downstream side of the throttle valve 15, a surge tank 17 is provided.
7 is provided with an intake pipe pressure sensor 18 for detecting the intake pipe pressure. The surge tank 17 has an intake manifold 19 for introducing air into each cylinder of the engine 11.
Are provided, and fuel injection valves 20 for injecting fuel are respectively mounted near intake ports of the intake manifold 19 of each cylinder. An ignition plug 21 is attached to a cylinder head of each cylinder, and a coolant temperature sensor 22 for detecting a coolant temperature is attached to a cylinder block of the engine 11.

Further, as shown in FIG.
Means that the power from the crankshaft 25 is
6 (or timing belt) for each sprocket 2
Intake camshaft 29 and exhaust camshaft 30 via
And is transmitted to. However, the intake camshaft 29 is provided with a variable valve timing device 32 that varies the rotation timing of the intake camshaft 29 with respect to the crankshaft 25 to vary the valve timing of the intake valve 31. The oil in the oil pan 33 is supplied to the oil pump 3 by the hydraulic control circuit of the variable valve timing device 32.
4, the hydraulic pressure is supplied through a hydraulic control valve 35, and the hydraulic pressure is controlled by the hydraulic control valve 35, whereby the valve timing of the intake valve 31 is controlled.

A cam angle sensor 36 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 29, while on the outer peripheral side of the crankshaft 25. A crank angle sensor 37 that outputs a crank angle signal for each predetermined crank angle is provided. Output signals of the cam angle sensor 36 and the crank angle sensor 37 are output to an engine control circuit (hereinafter referred to as “ECU”) 3.
8 and the ECU 38 controls the intake valve 31
The actual valve timing (actual camshaft phase) is calculated, and the engine rotation speed is calculated from the frequency of the output pulse of the crank angle sensor 37.

Output signals from the various sensors described above (throttle opening sensor 16, intake pipe pressure sensor 18, cooling water temperature sensor 22, etc.) are also input to ECU 38. This E
The CU 38 performs fuel injection control and ignition control based on these various input signals, performs variable valve timing control, and sets the actual valve timing of the intake valve 31 (the actual camshaft phase of the intake camshaft 29) to the target valve. The variable valve timing device 32 (hydraulic control valve 35) is feedback-controlled so as to match the timing (target camshaft phase).

Next, the configuration of the variable valve timing device 32 with the intermediate lock mechanism will be described with reference to FIGS. Housing 39 of variable valve timing device 32
Are fixed to the sprocket 27 rotatably supported on the outer periphery of the intake side camshaft 29 by bolts 40. Thus, the rotation of the crankshaft 25 is transmitted to the sprocket 27 and the housing 39 via the timing chain 26.
And the sprocket 27 and the housing 39 rotate in synchronization with the crankshaft 25. On the other hand, the intake side camshaft 2
A rotor 41 is fixedly fastened to one end of the 9 by a bolt 43 via a stopper 42. This rotor 41
Are housed in the housing 39 so as to be relatively rotatable.

As shown in FIG. 4, a plurality of fluid chambers 44 are formed inside the housing 39.
The vane 45 formed on the outer periphery of the rotor 41 partitions the chamber into an advance chamber 46 and a retard chamber 47.

As shown in FIG. 3, when the oil pump 34 is driven by the power of the engine 11, the oil pumped from the oil pan 33 causes the advance groove 48 of the intake camshaft 29 to pass through the hydraulic control valve 35. And into the retard groove 49. The advance oil passage 50 connected to the advance groove 48 is connected to the rotor 4.
1 communicates with each advance chamber 46 through an arc-shaped advance oil passage 51 (see FIG. 4) formed on the left side surface. On the other hand, the retard oil passage 52 connected to the retard groove 49 communicates with each of the retard chambers 47 through an arc retard oil passage (not shown) formed on the right side surface of the rotor 41. .

The hydraulic control valve 35 is a four-port, three-position switching valve that drives a valve body by a solenoid 53 and a spring 54. The valve body is moved between a position for supplying hydraulic pressure to the advance chamber 46 and a retard chamber. The position is switched between a position where hydraulic pressure is supplied to 47 and a position where hydraulic pressure is not supplied to both the advance chamber 46 and the retard chamber 47. When the solenoid 53 is energized, the valve body is switched to a position for supplying hydraulic pressure to the advance chamber 46, and hydraulic pressure acts in a direction to advance the camshaft phase.

In a state where a hydraulic pressure equal to or more than a predetermined pressure is supplied to the advance chamber 46 and the retard chamber 47, the vane 45 is fixed by the hydraulic pressure of the advance chamber 46 and the retard chamber 47, and The rotation of the housing 39 causes the rotation of the rotor 41 via oil.
(The vane 45), and the intake-side camshaft 29 is driven to rotate integrally with the rotor 41. During operation of the engine, the hydraulic pressure in the advance chamber 46 and the retard chamber 47 is controlled by the hydraulic control valve 35 to relatively rotate the housing 39 and the rotor 41 (vane 45), so that the intake side cam with respect to the crankshaft 25. The valve timing of the intake valve 31 is varied by controlling the rotation phase (camshaft phase) of the shaft 29. The sprocket 27 has a torsion coil spring 6 that assists with a spring force the hydraulic pressure for relatively rotating the rotor 41 in the advance direction at the time of advance control.
1 (see FIG. 3) are accommodated.

As shown in FIG. 4, a lock pin 56 for locking the relative rotation between the housing 39 and the rotor 41 (vane 45) is accommodated in a lock pin accommodation hole 55 formed in the vane 45. The lock pin 56 is provided with a lock hole 57 provided in the housing 39 (see FIG. 3).
, The camshaft phase is locked at a substantially middle position (lock position) of the adjustable range. This lock position is set to a position suitable for starting.

The lock pin 56 has a lock pin receiving hole 55
Is slidably inserted into a cylindrical member 58 fitted on the inner circumference of the, and is urged in a locking direction (projection direction) by a spring 59 (see FIG. 3). These lock pins 5
6, a lock hole 57, a spring 59 and the like constitute a lock mechanism.

When the engine is stopped, the lock pin 56 is held in the lock hole 57 by the spring 59 in the locked state, and the camshaft phase is locked at the locked position. Therefore, the engine is started in a locked state in which the lock pin 56 is fitted in the lock hole 57. When the discharge pressure of the oil pump 34 rises to some extent after the engine is started, the lock pin 56 is pressed by the oil pressure into the lock hole 57. From the lock pin to the unlock position.
6 is unlocked.

During operation of the engine, the lock pin 56 is hydraulically operated.
Is held at the lock release position, and the housing 39 and the rotor 41 are held in a state where they can be relatively rotated (that is, a state where variable valve timing control is possible). The ECU 38
Actual valve timing of the intake valve 31 (intake side camshaft 2
The hydraulic control valve 35 of the variable valve timing device 32 is feedback-controlled so that the actual camshaft phase 9 of the variable valve 9 coincides with the target valve timing (the target camshaft phase of the intake camshaft 29). Thus, by controlling the oil pressure in the advance chamber 46 and the retard chamber 47 to relatively rotate the housing 39 and the rotor 41, the camshaft phase is changed and the intake valve 3 is changed.
The first actual valve timing is made to coincide with the target valve timing.

Thereafter, when the engine 11 is stopped,
When the engine rotation speed decreases, the rotation speed of the oil pump 34 decreases and the oil pressure decreases. Therefore, when the oil pressure decreases, the spring force of the spring 59 that urges the lock pin 56 in the locking direction overcomes the oil pressure. The lock pin 56 projects by the spring force of the spring 59 and fits into the lock hole 57. However, in order for the lock pin 56 to be fitted into the lock hole 57, the two positions must match, that is, the camshaft phase must match the lock position.

When the engine 11 stops, the engine rotation speed (the rotation speed of the oil pump 34) decreases and the oil pressure decreases, so that the camshaft phase naturally shifts to the retard side due to the load torque of the camshaft 29. It changes. For this reason, if the camshaft phase is controlled to the advanced side of the lock position immediately before the engine stops, the camshaft phase changes to the retard side and reaches the lock position when the engine stops. By locking the lock pin 56 into the lock hole 57, the camshaft phase can be locked at the lock position. But,
If the camshaft phase is controlled to be more retarded than the lock position just before the engine stops, the camshaft phase will be shifted to the lock position even if the camshaft phase changes to the retard side due to a decrease in oil pressure when the engine is stopped. Does not reach (lock pin 58 is locked
9), the camshaft phase cannot be locked at the lock position.

The ECU 38 executes the stop camshaft phase advance control program shown in FIG. 5 stored in the ROM (storage medium) to execute the intake air increase control when an engine stop command is issued. Implementation of ISC valve 24
Is fully opened to increase the amount of intake air, hydraulic pressure advance control is performed, and the energization of the solenoid 53 of the hydraulic control valve 35 is stopped to control the hydraulic pressure in the advance direction. Thereby, when the engine 11 is stopped, the camshaft phase is advanced so that the lock can be reliably performed at the lock position.

Here, the advancing action of the camshaft phase by the intake air increase control will be described with reference to FIG.

An engine stop command is issued and the engine 11
When combustion of fuel (fuel injection and ignition) is stopped, the engine 1
1 (rotation of the crankshaft 25) is stopped. During this time, torque in the positive rotation direction (positive torque) due to inertia of the flywheel and the like and loss torque due to friction and the like act on the crankshaft 25. Further, until the rotation of the engine 11 is completely stopped, the intake air is compressed and expanded by the piston in the compression stroke and the expansion stroke of each cylinder even after the combustion is stopped. (Negative torque) is generated and a torque in the positive rotation direction (positive torque) is generated in the expansion stroke. However, after the combustion is stopped, the positive torque generated in the expansion stroke becomes smaller, so that the negative torque is relatively smaller than the positive torque. The rotation of the crankshaft 25 is braked by the negative torque and the loss torque such as friction, and the rotation of the crankshaft 25 is reduced and stopped.

When the ISC valve 24 is fully opened and the intake air amount is increased after the engine stop command as in the present embodiment, the negative torque generated by the compression of the intake air in the compression stroke is reduced as shown by the broken line in FIG. growing. Therefore, at the moment when the rotation of the crankshaft 25 in the forward rotation direction is stopped, the crankshaft 25 is slightly pushed back in the reverse rotation direction by this large negative torque and then stopped. At this time, since the oil pressure in the variable valve timing device 32 has dropped so much that the camshaft phase cannot be fixed by the oil pressure, even if the crankshaft 25 (vane 45) rotates slightly in the reverse direction, the reverse rotation is variable. It is hardly transmitted to the housing 39 (the intake camshaft 29) of the valve timing device 32. For this reason, only the crankshaft 25 (the vane 45) rotates slightly in the reverse direction with the housing 39 (the intake-side camshaft 29) of the variable valve timing device 32 almost stopped, whereby the camshaft with respect to the crankshaft 25 is rotated. The phase is relatively advanced. Thus, when the engine is stopped, the camshaft phase is advanced to the lock position by the intake air increase control, and the lock can be reliably performed at the lock position.

Hereinafter, the processing contents of the stop camshaft phase advance control program of FIG. 5 executed by the ECU 38 will be described.
This program is executed at a predetermined cycle while the ECU 38 is operating. When the program is started, first, in step 101, it is determined whether or not an engine stop command has been issued based on whether or not the ignition switch 60 (see FIG. 1) has been turned off. If ignition switch 6
If it is determined that 0 is on, the program ends without performing the subsequent processing.

Thereafter, if it is determined that the ignition switch 60 has been turned off and an engine stop command has been issued, the stop camshaft phase advance control in step 102 and thereafter is performed. In the present embodiment, when the ignition switch 60 is turned off, fuel injection and ignition are stopped. However, even after the ignition switch 60 is turned off, the main relay is kept on for a predetermined time and the ECU 38 and the ISC valve 2
4. Power can be supplied to the hydraulic control valve 35 and the like, and during that period, the stop camshaft phase advance control can be executed as follows.

First, in step 102, the intake air increase control is performed to fully open the ISC valve 24 (duty ratio =
100%) to increase the amount of intake air. Thereby, the negative torque (torque in the reverse rotation direction) generated by the compression of the intake air in the compression stroke is increased. The processing of step 102 plays a role corresponding to the intake air increase control means referred to in the claims.

Thereafter, the routine proceeds to step 103, where the hydraulic advance control is performed to energize the solenoid 53 of the hydraulic control valve 35, and the valve body of the hydraulic control valve 35 is brought to a position for supplying hydraulic pressure to the advance chamber 46. Switch. As a result, the oil pressure is applied in a direction to advance the camshaft phase, and at the same time, the oil pressure in the retard chamber 47 is discharged to the drain. At this time, after the engine stop command, fuel injection and ignition are stopped, so the engine rotation speed (oil pump rotation speed) decreases and the oil pressure decreases. With the aid of the spring force of the torsion coil spring 61 in the advance angle direction, the advance angle can be controlled by hydraulic pressure.

After the hydraulic advance control is started, the routine proceeds to step 104, where the camshaft phase (the intake valve 31) calculated based on the output signals of the crank angle sensor 37 and the cam angle sensor 36 is calculated.
It is determined whether or not the actual valve timing has advanced beyond the lock position. If the camshaft phase has not advanced beyond the lock position, the process proceeds to step 105, and the hydraulic advance control (stopping the energization of the solenoid 53) ) To continue.

On the other hand, if it is determined in step 104 that the camshaft phase has advanced from the lock position, the process proceeds to step 106, where the hydraulic control valve 35 adjusts the camshaft phase to the lock position. Feedback control. The processing of steps 103 to 106 plays a role corresponding to the hydraulic control means in the claims.

Thereafter, the process proceeds from step 105 or 106 to step 107, where it is determined whether or not the engine 11 has completely stopped (whether or not the engine speed is zero). 104, and the intake air increase control is continued (ISC valve 2
4 is kept fully open), the advance control or feedback control of the camshaft phase by the hydraulic pressure is repeated (step 1).
04-106).

Thereafter, at step 107, the engine 11
When it is determined that has stopped completely, step 108
Then, the energization of the ISC valve 24 is terminated, the intake air increase control is terminated, and then the present program is terminated.

In the present embodiment described above, when the ignition switch 60 is turned off, the solenoid 53 of the hydraulic control valve 35 is energized, and the valve body of the hydraulic control valve 35 switches to a position for supplying hydraulic pressure to the advance chamber 46. Therefore, when the engine 11 stops, the camshaft phase changes in the advance direction due to the hydraulic pressure. Thereafter, when the camshaft phase has advanced beyond the lock position, the hydraulic control valve 35 is feedback-controlled to return the camshaft phase to the lock position.
If the spring force of the spring 59 of the lock pin 56 overcomes the oil pressure while the camshaft phase is controlled near the lock position by such a hydraulic pressure advance control or feedback control, the lock pin 56 locks. The cam shaft is fitted in the hole 57 and the camshaft phase is locked at the lock position. Thereafter, the engine 11 stops.

However, when the ignition switch 60 is turned off while the engine load is relatively large (for example, the shift position of the automatic transmission is shifted to the power transmission position such as the D range). Since the engine speed drops sharply and the oil pressure drops sharply compared to when the engine is stopped normally, the time during which the camshaft phase can be advanced by hydraulic pressure is very short, and the camshaft phase is advanced to the lock position and locked. You may not be able to.

In this regard, in this embodiment, as shown in FIG. 7, when the ignition switch 60 is turned off, the ISC
Since the valve 24 is fully opened to increase the amount of intake air, the negative torque generated by the compression of the intake air during the compression stroke increases. Therefore, at the moment when the rotation of the crankshaft 25 in the forward rotation direction is stopped, the crankshaft 25 is slightly pushed back in the reverse rotation direction by this large negative torque and then stopped. Therefore, if the camshaft phase is not locked by the time the crankshaft 25 rotates in the reverse direction, the camshaft phase can be advanced to the lock position by the reverse rotation of the crankshaft 25, and the camshaft phase can be shifted to the lock position. Can be locked with.

As is clear from the above description, in the present embodiment, even when the camshaft phase cannot be advanced to the lock position by the hydraulic pressure control of the camshaft phase when the engine is stopped, the camshaft phase control is performed by the intake air increase control. , The camshaft phase can be securely locked at the lock position, the startability of the next engine can be improved, and noise due to the vibration of the vane 45 at the time of start can be prevented. . In addition, the lock control of the camshaft phase is performed after the ignition switch 60 is turned off (after the fuel injection is stopped).
Therefore, there is no adverse effect on combustion during operation of the engine and no deterioration of exhaust emission occurs.

In this embodiment, when the engine 11 is stopped, the ISC valve 24 is opened to perform the intake air increase control. Therefore, a dedicated intake air amount for increasing the intake air when the engine is stopped. The intake air amount increase control can be performed without newly providing a regulating valve, and the cost can be reduced.

An electronic throttle system for driving the throttle valve with a motor and a throttle opener mechanism for opening the throttle valve with a diaphragm actuator or the like when the engine is stopped to prevent foreign substances from sticking or freezing of the throttle valve when the engine is stopped. In the system provided with, the intake air increase control may be performed by opening the throttle valve when the engine stops. Also in this case, there is no need to provide a dedicated intake air amount adjusting valve, and the cost can be reduced.

However, the present invention may be configured to provide a dedicated intake air amount adjustment valve for increasing the intake air when the engine is stopped. Even in this case, the intended object of the present invention can be sufficiently achieved. it can.

In this embodiment, when the engine 11 is stopped, both the intake air increase control and the hydraulic advance control are performed. However, only the intake air increase control may be performed. .

In this embodiment, when the ignition switch 60 is turned off, the intake air increase control is performed. However, in order to improve fuel efficiency, an automatic engine stop device for automatically stopping the engine at idle or the like is provided. In a mounted vehicle (for example, a hybrid car), the intake air increase control may be performed for each engine stop command by the automatic engine stop device.

In addition, according to the present invention, the configuration of the variable valve timing device and the configuration of the lock mechanism may be appropriately changed.
Further, the present invention may be applied to a variable valve timing control device for an exhaust valve, and various changes can be made without departing from the scope of the invention.

[Brief description of the drawings]

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

FIG. 2 is a front view of a variable valve timing device and peripheral parts thereof.

FIG. 3 is a longitudinal sectional view of a variable valve timing device.

FIG. 4 is a sectional view taken along the line AA in FIG. 3;

FIG. 5 is a flowchart showing a processing flow of a camshaft phase advance control program at the time of stop;

FIG. 6 is a diagram for explaining an advance effect of a camshaft phase by intake air increase control;

FIG. 7 is a time chart showing an execution example of the embodiment;

FIG. 8 is a sectional view of a conventional variable valve timing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 15 ... Throttle valve, 24 ... ISC valve (Bypass air amount adjustment valve), 25 ... Crankshaft, 26 ... Timing chain, 27,28 ... Sprocket, 29 ... Intake side Camshaft,
Reference numeral 30: exhaust side cam shaft, 31: intake valve, 32: variable valve timing device, 34: oil pump, 35: hydraulic control valve, 38: ECU (intake air increase control means, hydraulic control means), 39: housing, 41 ... rotor, 44 ... fluid chamber, 45 ... vane, 46 ... advance chamber, 47 ... retard chamber, 5
2 ..., 53 ... solenoid, 54 ... spring, 56 ... lock pin (lock mechanism), 57 ... lock hole (lock mechanism), 59 ... spring (lock mechanism), 60 ... ignition switch.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02D 9/02 F02D 9/02 T 17/00 17/00 M 41/04 310 41/04 310H 315 315 320 320 320 / 00 310 45/00 310A 312 312G F02N 17/00 F02N 17/00 Z (72) Inventor Shigeyuki Kusano 1-1-1 Showa-cho, Kariya-shi, Aichi F term in DENSO Corporation 3G018 BA33 CA20 DA18 DA71 EA02 EA21 EA22 EA31 FA16 GA02 GA11 3G065 AA11 CA12 DA05 DA06 DA15 EA06 FA03 GA00 GA01 GA05 GA09 GA10 GA41 HA06 HA22 KA02 3G084 BA05 BA06 BA23 CA01 CA07 DA04 EA11 EB12 FA07 FA10 FA11 FA20 FA33 FA36 FA10 3103 EC08 FA11 FA31 GA10 HA06X HA10X HA13X HA13Z HE01Z HF20Z 3G301 JA03 KA01 KA28 LA01 LA04 LA07 ND02 PA01Z PA07Z PA11Z PE01Z PE03Z PE08Z PF16Z

Claims (4)

[Claims] 1. A variable valve timing device that varies a valve timing by changing a rotation phase of a camshaft with respect to a crankshaft of an internal combustion engine (hereinafter referred to as a “camshaft phase”). A variable valve timing control device for an internal combustion engine that locks the camshaft phase at the lock position when the internal combustion engine is started is provided with a lock mechanism that locks at a substantially intermediate lock position. A variable valve timing control device for an internal combustion engine, comprising: intake air increase control means for performing control for increasing the intake air amount (hereinafter referred to as “intake air increase control”). 2. The intake air increase control means performs the intake air increase control by opening a bypass air amount adjustment valve that adjusts an intake air amount that bypasses a throttle valve. 3. The variable valve timing control device for an internal combustion engine according to claim 1. 3. The variable valve timing control device for an internal combustion engine according to claim 1, wherein the intake air increase control means performs the intake air increase control by opening a throttle valve. 4. A hydraulic control valve for controlling a hydraulic pressure for driving the variable valve timing device, and controlling the hydraulic control valve to advance the camshaft phase when a stop command for the internal combustion engine is issued. The variable valve timing control device for an internal combustion engine according to any one of claims 1 to 3, further comprising a hydraulic control unit that performs the control.