JP3761018B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine control apparatus in which variable valve timing devices are provided for both an intake valve and an exhaust valve of an internal combustion engine.
[0002]
[Prior art]
In recent years, an increasing number of internal combustion engines mounted on vehicles adopt a variable valve timing control device for the purpose of improving output, reducing fuel consumption, and reducing exhaust emissions. For example, as shown in FIG. 13, the basic configuration of a hydraulically driven variable valve timing control device is connected to a housing 1 that rotates in synchronization with a crankshaft of an engine and a camshaft of an intake (or exhaust) valve. The rotor 2 is coaxially arranged, and the fluid chamber 3 formed in the housing 1 is divided into an advance chamber 5 and a retard chamber 6 by a vane 4 provided in the rotor 2. Then, the hydraulic pressure in the advance chamber 5 and the retard chamber 6 is controlled by a hydraulic control valve so that the housing 1 and the rotor 2 (vane 4) are rotated relative to each other, thereby rotating the cam shaft relative to the crankshaft (cam shaft). The valve timing is variably controlled by changing the phase.
[0003]
The conventional hydraulically driven variable valve timing control device is the most retarded valve timing of the intake valve when the engine is stopped (when the hydraulic pressure is lowered) in order to prevent noise caused by the vibration of the vane 4 at the start. The relative rotation between the housing 1 and the rotor 2 (vane 4) is locked by the lock pin 7 at the retarded phase. Therefore, since the engine is started at the most retarded phase at the start, the most retarded phase is set to a phase suitable for starting.
[0004]
However, in this configuration, since the most retarded angle phase is limited by the phase at start (lock phase), the adjustable range of valve timing is limited by the lock phase, and the adjustable range of valve timing is narrow. There are drawbacks.
[0005]
Therefore, as shown in Japanese Patent Laid-Open No. 9-324613, it has been proposed to expand the adjustable range of the valve timing by setting the lock phase when the engine is stopped to approximately the middle of the adjustable range of the valve timing. Yes. In this configuration, when the engine is started, the engine is started with the valve timing locked in the intermediate lock phase, and then the advance chamber 5 is delayed due to the increase in hydraulic pressure accompanying the increase in engine rotation speed (oil pump rotation speed). When the hydraulic pressure in the corner chamber 6 increases, the lock pin 7 is pushed out of the lock hole by the hydraulic pressure, and the lock of the lock pin 7 is released. After unlocking, the variable valve timing control can be executed, and the hydraulic control valve is feedback controlled so that the actual valve timing matches the target valve timing.
[0006]
[Problems to be solved by the invention]
Currently, many of the variable valve timing systems in practical use control the advance angle of the valve timing of the intake valve according to the engine operating state. Recently, in order to further improve the variable valve timing control performance, the intake valve A valve timing device has been developed for both the exhaust valve and the exhaust valve. In this case, when the variable valve timing control is performed in a state where the lock mechanism that locks the valve timing becomes defective and the lock is not released, only the variable valve timing device that operates normally operates normally. The valve overlap amount of the intake / exhaust valve may become abnormal, and the exhaust gas residual ratio (internal EGR amount) in the cylinder of the engine may become excessive, which causes the engine combustion state to deteriorate and misfires occur. Or, drivability and exhaust emissions deteriorate, and in the worst case, engine stall may occur.
[0007]
The present invention has been made in view of such circumstances. Accordingly, the object of the present invention is to prevent the combustion state of the internal combustion engine from deteriorating even when the lock mechanism that locks the valve timing with the intermediate lock phase malfunctions. It is an object of the present invention to provide a control device for an internal combustion engine that can be reduced, can improve drivability and exhaust emission, and can prevent engine stall.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a control device for an internal combustion engine according to claim 1 of the present invention is a lock that locks valve timing at an intermediate lock phase in an internal combustion engine in which variable valve timing devices are respectively provided for an intake valve and an exhaust valve. The presence or absence of a malfunction of the mechanism is determined by the locking malfunction determination means, and when it is determined that the locking mechanism malfunctions, the variable valve timing device that operates normally has an exhaust residual ratio (internal EGR amount) in the cylinder. Control is performed by the abnormal time control means so as to reduce the number. In this way, it is possible to suppress the increase in the exhaust gas remaining ratio in the cylinder due to the malfunction of the lock mechanism, thereby reducing the deterioration of the combustion state of the internal combustion engine when the lock mechanism malfunctions and preventing misfire. It is possible to improve drivability and exhaust emission and to prevent engine stall.
[0009]
Further, in a system equipped with an exhaust gas recirculation device, the variable valve timing device that operates normally when the locking mechanism malfunctions reduces the exhaust residual ratio (internal EGR amount) in the cylinder. It is also possible to control so that the exhaust gas flow rate (external EGR amount) by the exhaust gas recirculation device is reduced. In other words, both internal EGR and external EGR have the same effect on flammability, and the total of the internal EGR amount and external EGR amount is the total EGR amount. However, 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 internal combustion engine can be prevented.
[0010]
It should be noted that, as in claim 3, it may be possible to deal with only the control for reducing the external EGR amount when the lock mechanism malfunctions. Even in this case, the deterioration of the combustion state of the internal combustion engine can be reduced.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment (1)]
Embodiment (1) of the present invention will be described below with reference to FIGS. First, a schematic configuration of the entire system will be described with reference to FIG. In the DOHC engine 11 that is an internal combustion engine, the power from the crankshaft 12 is transmitted to the intake side camshaft 16 and the exhaust side camshaft 17 through the sprockets 14 and 15 by the timing chain 13. The intake side camshaft 16 is provided with a hydraulically driven intake side variable valve timing device 18 that adjusts the advance angle of the intake side camshaft 16 with respect to the crankshaft 12. An intake side cam angle sensor 19 that outputs an intake side cam angle signal for each cam angle is attached. The exhaust side camshaft 17 is provided with a hydraulically driven exhaust side variable valve timing device 20 that adjusts the advance angle of the exhaust side camshaft 17 with respect to the crankshaft 12. An exhaust-side cam angle sensor 21 that outputs an exhaust-side cam angle signal at every predetermined cam angle is attached. On the other hand, a crank angle sensor 22 that outputs a crank angle signal for each predetermined crank angle is attached to the crankshaft 12.
[0012]
The output signals of the crank angle sensor 22 and the intake side / exhaust side cam angle sensors 19 and 21 are input to an engine control circuit (hereinafter referred to as “ECU”) 23, and the ECU 23 controls the intake valve and the exhaust valve. The valve timing is calculated, and the engine rotation speed is calculated based on the frequency of the crank angle signal of the crank angle sensor 22. Although not shown, the outputs of various sensors for detecting engine operating conditions such as an intake pipe pressure sensor, a water temperature sensor, and a throttle sensor are also input to the ECU 23, and the target valves of the intake valve and the exhaust valve are based on these various sensor outputs. Timing (a target advance amount of the intake camshaft 16 and a target retard amount of the exhaust camshaft 17) is calculated.
[0013]
The ECU 23 feeds back the intake side variable valve timing device 18 by controlling the intake side hydraulic control valve 24 so that the actual valve timing of the intake valve (actual advance angle of the intake camshaft 16) matches the target advance angle. The exhaust side variable valve timing device 20 is controlled by controlling the exhaust side hydraulic control valve 25 so that the actual valve timing of the exhaust valve (actual retardation amount of the exhaust side camshaft 17) matches the target retardation amount. Feedback control.
[0014]
Next, the configuration of the intake side variable valve timing device 18 with a lock mechanism will be described with reference to FIGS. A housing 31 of the variable valve timing device 18 is fastened and fixed with bolts 32 to a sprocket 14 that is rotatably supported on the outer periphery of the intake camshaft 16. Thereby, the rotation of the crankshaft 12 is transmitted to the sprocket 14 and the housing 31 through the timing chain 13, and the sprocket 14 and the housing 31 rotate in synchronization with the crankshaft 12.
[0015]
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 and fixed to one end portion of the intake side camshaft 16 with a bolt 37 via a stopper 36. . The rotor 35 is housed in the housing 31 so as to be relatively rotatable.
[0016]
As shown in FIGS. 3 and 4, a plurality of fluid chambers 40 are formed inside the housing 31, and each fluid chamber 40 is retarded from the advance chamber 42 by a vane 41 formed on the outer periphery of the rotor 35. It is partitioned into a corner chamber 43. Seal members 44 are attached to the outer periphery of the rotor 35 and the outer periphery of the vane 41, and each seal member 44 is urged in the outer peripheral direction by a leaf spring 45 (see FIG. 2). Thereby, the clearance between the outer peripheral surface of the rotor 35 and the inner peripheral surface of the housing 31 and the clearance 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.
[0017]
As shown in FIG. 2, an annular advance groove 46 and a retard groove 47 formed in the outer peripheral portion of the intake side camshaft 16 are connected to predetermined ports of the hydraulic control valve 24, respectively. By driving the pump 28, the oil pumped from the oil pan 27 is supplied to the advance groove 46 and the retard groove 47 through the hydraulic control valve 24. The advance oil passage 48 connected to the advance groove 46 passes through the inside of the intake side camshaft 16 and communicates with an arcuate advance oil passage 49 (see FIG. 3) formed on the left side surface of the rotor 35. The arcuate advance oil passage 49 communicates with each advance chamber 42. On the other hand, the retarding oil passage 50 connected to the retarding groove 47 penetrates the inside of the intake side camshaft 16 to an arcuate retarding oil passage 51 (see FIG. 4) formed on the right side surface of the rotor 35. The arc retarded oil passage 51 is formed so as to communicate with each other, and communicates with each retarded angle chamber 43.
[0018]
The hydraulic control valve 24 is a four-port three-position switching valve that drives the valve body with a solenoid 53 and a spring 54, and the position of the valve body is hydraulic to the advance chamber 42 and to the retard chamber 43. The position is switched between a position where the hydraulic pressure is supplied and a position where no hydraulic pressure is supplied to either the advance chamber 42 or the retard chamber 43. When the energization of the solenoid 53 is stopped, the valve element is automatically switched to a position where the hydraulic pressure is supplied to the advance chamber 42 by the spring 54 so that the hydraulic pressure works in a direction to advance the camshaft phase.
[0019]
In a state where the hydraulic pressure higher than a predetermined pressure 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 housing 31 is rotated by the rotation of the crankshaft 12. The rotation is transmitted to the rotor 35 (vane 41) through the oil, and the intake side camshaft 16 is rotationally driven integrally with the rotor 35. During engine operation, the hydraulic pressure in the advance chamber 42 and the retard chamber 43 is controlled by the hydraulic control valve 24 to rotate the housing 31 and the rotor 35 (vane 41) relative to each other, so The valve timing of the intake valve is varied by controlling the rotation phase (cam shaft phase) of the shaft 16. Note that the sprocket 14 accommodates a torsion coil spring 55 (see FIG. 2) that assists the hydraulic pressure that causes the rotor 35 to relatively rotate in the advance direction at the time of advance angle control with a spring force.
[0020]
Further, as shown in FIGS. 3 and 4, stopper portions 56 for restricting the relative rotation range of the rotor 35 (vane 41) with respect to the housing 31 are formed on both side portions of any one vane 41. The portion 56 regulates the most retarded angle phase and the most advanced angle phase of the cam shaft phase. Furthermore, a lock pin 58 for locking relative rotation between the housing 31 and the rotor 35 (vane 41) is accommodated in the lock pin accommodation hole 57 formed in the other vane 41, and this lock pin 58 is accommodated in the housing. The camshaft phase is locked at a substantially intermediate position (intermediate lock phase) within the adjustable range by being fitted into a lock hole 59 (see FIG. 2) provided in 31. This intermediate lock phase is set to a phase suitable for starting.
[0021]
As shown in FIGS. 6 and 7, the lock pin 58 is slidably inserted into the cylindrical member 61 fitted to the inner periphery of the lock pin accommodation hole 57, and is locked in the locking direction (protruding direction) by the spring 62. It is energized. Further, a gap between the cylindrical member 61 and the lock pin 58 is divided into a lock hydraulic chamber 64 and a lock release holding hydraulic chamber 65 by a valve portion 63 formed at the center outer peripheral portion of the lock pin 58. Then, in order to supply hydraulic pressure from the advance chamber 42 to the lock hydraulic chamber 64 and the lock release holding hydraulic chamber 65, the vane 41 has a lock oil passage 66 communicating with the advance chamber 42 and an unlock release holding fluid. An oil passage 67 is formed. The housing 31 is formed with an unlocking oil passage 68 that communicates the lock hole 59 and the retard chamber 43.
[0022]
As shown in FIG. 6, when the lock pin 58 is locked, the valve portion 63 of the lock pin 58 closes the lock release holding oil passage 67, and the lock oil passage 66 communicates with the lock hydraulic chamber 64. . As a result, hydraulic pressure is supplied from the advance chamber 42 to the lock hydraulic chamber 64, and the lock pin 58 is held in the lock hole 59 by the hydraulic pressure and the spring 62, and the camshaft phase is locked at the intermediate lock phase. Is done.
[0023]
While the engine is stopped, the hydraulic pressure in the lock hydraulic chamber 64 (the hydraulic pressure in the advance chamber 42) decreases, but the lock pin 58 is held in the locked position by the spring 62. Therefore, the engine is started with the lock pin 58 held in the locked position (intermediate lock phase). After the engine is started, if the hydraulic pressure in the lock hole 59 (hydraulic pressure in the retarding chamber 43) increases, the hydraulic pressure The lock pin 58 is unlocked as follows. After the engine is started, the hydraulic pressure (force in the unlocking direction) supplied from the retard chamber 43 through the unlocking oil passage 68 to the lock hole 59 is the hydraulic pressure in the lock hydraulic chamber 64 (hydraulic pressure in the advance chamber 42) and the spring 62. When the resultant force becomes larger than the resultant force (the force in the lock direction), 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 unlock position shown in FIG. 7, and the lock pin 58 is unlocked. Is done.
[0024]
In this unlocked state, as shown in FIG. 7, the valve portion 63 of the lock pin 58 blocks the lock oil passage 66, and the unlocking and holding oil passage 67 communicates with the unlocking and holding hydraulic chamber 65. It becomes a state. As a result, 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 (hydraulic pressure of the advanced chamber 42) and the hydraulic pressure (retarding angle) of the lock hole 59. The lock pin 58 is held in the unlocked position against the spring 62 by the hydraulic pressure of the chamber 43.
[0025]
During engine operation, the hydraulic pressure of either the advance chamber 42 or the retard chamber 43 is high, so that the lock pin 58 is held at the unlocked position by the hydraulic pressure, and the housing 31 and the rotor 35 rotate relative to each other. It is held in a possible state (that is, a state in which variable valve timing control is possible).
[0026]
During engine operation, the engine control circuit 21 calculates the actual valve timing of the intake valve (actual advance angle position of the intake camshaft 16) based on the output signals of the crank angle sensor 20 and the cam angle sensor 19, and also performs the suction operation. The target valve timing of the intake valve (target advance angle position of the intake camshaft 17) is calculated based on the outputs of various sensors that detect engine operating conditions such as the atmospheric pressure sensor 22 and the water temperature sensor 23. Then, the hydraulic control valve 24 of the intake side variable valve timing device 18 is feedback-controlled so that the actual valve timing of the intake valve coincides with the target valve timing. As a result, the hydraulic pressure in the advance chamber 42 and the retard chamber 43 is controlled to rotate the housing 31 and the rotor 35 relative to each other, thereby changing the camshaft phase and setting the actual valve timing of the intake valve to the target valve timing. Match.
[0027]
After that, when the engine 11 is stopped, if the engine rotation speed decreases, the discharge pressure of the oil pump 28 decreases, so the hydraulic pressure in the advance chamber 42 and the retard chamber 43 decreases. As a result, the hydraulic pressure in the unlocking hydraulic chamber 65 (the hydraulic pressure in the advance chamber 42) and the hydraulic pressure in the lock hole 59 (hydraulic pressure in the retard chamber 43) are reduced, and the spring force of the spring 62 is reduced to these hydraulic pressures. When it is overcome, the lock pin 58 protrudes and fits into the lock hole 59 by the spring force of the spring 62. However, in order for the lock pin 58 to be fitted into the lock hole 59, it is a condition that the positions of both of them match, that is, the cam shaft phase matches the intermediate lock phase.
[0028]
When the engine 11 stops, the engine rotation speed (rotation speed of the oil pump 28) decreases and the hydraulic pressure decreases, so the camshaft phase naturally changes to the retard side due to 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, and the valve timing is locked at the intermediate lock phase.
[0029]
Although not shown, the exhaust side variable valve timing device 20 has the same configuration as a conventional variable valve timing device without a lock mechanism. Since the valve timing of the exhaust valve when starting the engine is the most advanced angle phase, when the variable valve timing control is started, the valve timing of the exhaust valve is controlled to the retard side (see FIG. 8).
[0030]
As described above, the engine is started in a state where the lock pin 58 of the intake side variable valve timing device 18 is held at the locked position (intermediate lock phase). When the hydraulic pressure (43) increases, the lock pin 58 is unlocked by the hydraulic pressure, and by releasing the lock, feedback control of the valve timing of the intake valve becomes possible, and variable valve timing control is started.
[0031]
However, after the engine is started, if the variable valve timing control is started in a state in which the lock is not released due to a malfunction of the lock pin 58, only the normally operated exhaust side variable valve timing device 20 operates on the retard side as usual. Therefore, the valve overlap amount (see FIG. 8) of the intake / exhaust valve becomes excessive, and the exhaust residual ratio (internal EGR amount) in the cylinder of the engine 11 may be excessive, and the combustion of the engine 11 may thereby occur. The situation worsens and misfires occur, drivability and exhaust emissions deteriorate, and in the worst case, engine stall may occur.
[0032]
Therefore, in the present embodiment (1), the ECU 23 repeatedly executes the lock mechanism fail-safe control program of FIG. 9 stored in the built-in ROM (storage medium) every predetermined time, and performs the lock pin 58 during the variable valve timing control. The deterioration of the combustion state of the engine 11 due to the malfunction is prevented as follows. When this program is started, first, at step 101, it is determined whether or not variable valve timing control is being executed (in other words, whether or not the unlocking control of the lock pin 58 has been completed), and the variable valve timing control is performed. If timing control is not being executed, the unlock failure flag is maintained OFF (step 105), and the program is terminated.
[0033]
On the other hand, if the variable valve timing control is being executed, the routine proceeds to step 102, where it is determined whether or not a lock release failure of the lock pin 58 has occurred. Here, the unlocking failure means that the lock pin 58 is not in the unlocked state during execution of the variable valve timing control. Determining whether or not unlocking is defective is, for example, determining whether the detected value of the valve timing of the intake valve is fixed at the intermediate lock phase and does not move at all, taking into account detection errors and manufacturing variations Just do it. The processing in step 102 serves as a lock operation failure determination means in the claims. If it is determined in step 102 that no unlock failure has occurred, the unlock failure flag is set to OFF (step 105), and the program ends.
[0034]
If it is determined in step 102 that an unlock failure has occurred, the process proceeds to step 103, the unlock failure flag is set to ON, and the exhaust side variable valve timing device 20 is exhausted in the next step 104. By controlling the valve timing of the valve to be the most advanced angle phase and reducing the valve overlap amount of the intake and exhaust valves, the internal EGR amount of the engine 11 is reduced and the deterioration of the combustion state is reduced. The processing in step 104 serves as an abnormality control means in the claims.
[0035]
An example of fail safe control by the lock mechanism fail safe control program of FIG. 9 described above will be described with reference to FIG. FIG. 10 is an example of fail-safe control when the lock pin 58 is fitted into the lock hole 59 and a lock release failure occurs during execution of the variable valve timing control.
[0036]
If a lock release failure occurs during execution of variable valve timing control, the lock release failure flag is set to ON, the valve timing of the exhaust valve is controlled to the most advanced angle phase, and the valve overlap amount of the intake and exhaust valves is set. By reducing, the amount of internal EGR of the engine 11 is reduced. Thereby, the deterioration of the combustion state of the engine 11 at the time of unlocking failure can be reduced and misfire can be prevented, drivability and exhaust emission can be improved, and engine stall can be prevented.
[0037]
The malfunction of the lock pin 58 includes a lock failure in addition to a lock release failure. The lock failure is a failure in which the lock pin 58 is not locked when the lock pin 58 needs to be locked (such as when the engine is started). When the lock pin 58 needs to be locked, normally, variable valve timing control is not performed. Therefore, even if a lock failure occurs, it is not always necessary to perform fail-safe control. However, since there is a possibility that the valve overlap amount of the intake / exhaust valve may increase arbitrarily, the same fail-safe control as that at the time of unlocking failure may be performed.
[0038]
[Embodiment (2)]
In the above embodiment (1), the valve timing of the exhaust valve is controlled to the most advanced angle phase at the time of unlocking failure, but the lock mechanism fail safe control program of the embodiment (2) of the present invention shown in FIG. Then, when the lock release is poor, the target value of the valve timing of the exhaust valve is corrected to the advance side by a predetermined correction amount α from the normal target value (step 104a). As a result, as shown in FIG. 10, the valve timing of the exhaust valve at the time of unlocking failure is advanced by a correction amount α from the normal amount to reduce the valve overlap amount of the intake and exhaust valves, thereby reducing the engine 11 The amount of internal EGR is reduced to prevent deterioration of the combustion state. At this time, the correction amount α of the valve timing may be changed by a map or the like according to the engine operating state, and may be a fixed value. In addition, the process of each step other than step 104a of FIG. 11 is the same as the process of each step of FIG. 9 demonstrated in the said embodiment (1).
[0039]
[Embodiment (3)]
Next, an embodiment (3) in which the present invention is applied to an engine equipped with an exhaust gas recirculation device will be described with reference to FIG. The structure of the exhaust gas recirculation device is not shown, but an EGR pipe for returning a part of the exhaust gas to the intake pipe is connected between the exhaust pipe and the intake pipe of the engine, and an EGR valve is provided in the middle of the EGR pipe. The external EGR amount is controlled by controlling the opening degree of the EGR valve by the ECU.
[0040]
The lock mechanism fail-safe control program of FIG. 12 is obtained by adding the process of step 106 to the program of FIG. 11 described in the embodiment (2). In this program, when the unlocking failure occurs, the target value of the valve timing of the exhaust valve is corrected to the advance side by a predetermined correction amount α from the normal target value (step 104a), and the target value of the external EGR amount is set to the normal value. Is corrected by a predetermined correction amount β from the target value (step 106). As a result, the valve timing of the exhaust valve at the time of unlocking failure is advanced by a correction amount α from the normal amount, the valve overlap amount of the intake and exhaust valves is reduced, and the internal EGR amount of the engine 11 is reduced. The target value of the external EGR amount is reduced by the correction amount β from the normal value. At this time, the correction amount β of the external EGR amount may be changed by a map or the like according to the engine operating state, and may be a fixed value.
[0041]
In this embodiment (3) described above, when the unlocking failure is detected, the valve timing of the exhaust valve is corrected to advance the internal EGR amount and the external EGR amount is reduced. The total EGR amount can be reliably reduced, and deterioration of the combustion state of the engine 11 can be prevented.
[0042]
In the present embodiment (3) as well, the valve timing of the exhaust valve may be controlled to the most advanced angle phase in the same way as in the above embodiment (1) when the lock release is poor. In addition, when the lock release is poor, it is also possible to perform only the correction for reducing the external EGR amount without performing the advance correction of the valve timing of the exhaust valve.
[0043]
In each of the above embodiments (1) to (3), the intake side variable valve timing device 18 is provided with a lock mechanism, but the exhaust side variable valve timing device 20 may be provided with a lock mechanism. In addition, a lock mechanism may be provided in each of the variable valve timing devices 18 and 20 on the intake side and the exhaust side. In this case, when the lock mechanism of the exhaust side variable valve timing device 20 is malfunctioning (unlocking failure), the intake side variable valve timing device 18 is controlled to the retard side so that the internal EGR amount is reduced, Alternatively, the opening degree of the EGR valve may be controlled so as to reduce the external EGR amount.
[0044]
In addition, the present invention can be implemented with various modifications within a range not departing from the gist, such as appropriately changing the configuration of the variable valve timing device and the configuration 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.
3 is a cross-sectional view taken along line AA in FIG.
4 is a cross-sectional view taken along line BB in FIG.
5 is a cross-sectional view taken along the line CC in FIG.
FIG. 6 is a partially enlarged sectional view showing a locked state of the lock pin.
FIG. 7 is a partially enlarged sectional view showing a lock pin unlocked state.
FIG. 8 is a graph showing opening / closing timing characteristics of an intake valve and an exhaust valve
FIG. 9 is a flowchart showing a processing flow of the lock mechanism fail-safe control program according to the embodiment (1).
FIG. 10 is a time chart showing an example of fail-safe control when the lock release is poor in the embodiments (1) and (2).
FIG. 11 is a flowchart showing a processing flow of a valve timing control program according to the embodiment (2).
FIG. 12 is a flowchart showing a processing flow of a valve timing control program according to the embodiment (3).
FIG. 13 is a sectional view of a conventional variable valve timing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Crankshaft, 13 ... Timing chain, 14, 15 ... Sprocket, 16 ... Intake camshaft, 17 ... Exhaust camshaft, 18 ... Intake side variable valve timing device, 19 ... Intake side cam Angle sensor, 20 ... exhaust side variable valve timing device, 21 ... exhaust side cam angle sensor, 22 ... crank angle sensor, 21 ... engine control circuit (lock operation failure detection means, abnormal time control means), 24 ... intake side hydraulic control Valve, 25 ... Exhaust side hydraulic control valve, 28 ... Oil pump, 31 ... Housing, 35 ... Rotor, 40 ... Fluid chamber, 41 ... Vane, 42 ... Advance chamber, 43 ... Delay chamber, 53 ... Solenoid, 54 ... Spring, 58 ... Lock pin (lock mechanism), 59 ... Lock hole (lock mechanism), 62 ... Spring (lock mechanism).

Claims (3)

A variable valve timing device that varies the valve timing is provided for each of the intake valve and the exhaust valve of the internal combustion engine, and at least one of the variable valve timing devices has a valve timing within an adjustable range when variable valve timing control is not performed. In a control device for an internal combustion engine provided with a lock mechanism that locks at a substantially intermediate position,
A lock operation failure determination means for determining presence or absence of operation failure of the lock mechanism;
An abnormality control means for controlling the variable valve timing device that normally operates when the lock operation failure determination means determines that the lock mechanism is not operating properly so that the residual ratio of exhaust in the cylinder of the internal combustion engine is reduced. And a control device for an internal combustion engine. An exhaust gas recirculation device for circulating a part of the exhaust gas of the internal combustion engine to the intake system;
The abnormal-time control means causes the variable valve timing device that operates normally to reduce the exhaust residual ratio in the cylinder of the internal combustion engine when the lock mechanism malfunction determination means determines that the lock mechanism malfunctions. 2. The control device for an internal combustion engine according to claim 1, wherein the control is performed so that an exhaust gas flow rate by the exhaust gas recirculation device is reduced. A variable valve timing device that varies the valve timing is provided for each of the intake valve and the exhaust valve of the internal combustion engine, and at least one of the variable valve timing devices has a valve timing within an adjustable range when variable valve timing control is not performed. In a control device for an internal combustion engine provided with an exhaust gas recirculation device that provides a lock mechanism that locks substantially in the middle and circulates part of the exhaust gas of the internal combustion engine to the intake system,
A lock operation failure determination means for determining presence or absence of operation failure of the lock mechanism;
An abnormality control means for controlling to reduce the exhaust gas flow rate by the exhaust gas recirculation device when it is determined that the lock mechanism malfunctions by the locking malfunction judgment means. Control device.

Images