JP2012097630A - Failure diagnosis device of variable valve timing control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform failure diagnosis of a lock pin by accurately detecting a VCT phase shift due to torque of a cam shaft during lock control of a variable valve timing control system with an intermediate lock mechanism.SOLUTION: A cam angle sensor 19 is set to output a delay side phase shift detecting signal when a VCT phase is delayed, and to output an advance side phase shift detecting signal when the VCT phase is advanced due to torque of a suction side cam shaft 16. During lock control for controlling a hydraulic control valve 25 so as to lock the VCT phase at an intermediate lock phase by projecting lock pins (an advance control pin and a delay control pin), a shift width of the VCT phase due to torque of the suction side cam shaft 16 is detected on the basis of the advance side phase shift detecting signal and the delay side phase shift detecting signal output from the cam angle sensor 19. A failure of the lock pin is determined by whether the shift width of the VCT phase is larger than the failure determination value.

Description

  The present invention relates to a variable valve timing control system having a function of locking a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine (engine) (hereinafter referred to as “VCT phase”) with an intermediate lock phase located within the adjustable range. The present invention relates to an abnormality diagnosis device.

  Conventionally, in a hydraulically driven variable valve timing device, as described in Patent Document 1 (Japanese Patent Laid-Open No. 9-324613) and Patent Document 2 (Japanese Patent Laid-Open No. 2001-159330), the engine is stopped. The lock phase is set approximately in the middle of the adjustable range of the VCT phase to expand the adjustable range of the valve timing (VCT phase). In this system, the intermediate lock phase that is locked when the engine is stopped is set to a phase suitable for starting, the engine is started with the lock pin locking the VCT phase at the intermediate lock phase, and the engine speed increases after the start is completed ( After the oil pressure rises to an appropriate oil pressure due to the oil pump rotation increase), the lock pin is retracted to unlock the VCT phase, and the VCT phase is feedback controlled to the target VCT phase according to the engine operating state. ing. When the engine is stopped or when a lock request is generated during idle operation, the lock pin is projected to lock the VCT phase with the intermediate lock phase.

JP-A-9-324613 JP 2001-159330 A

  During the phase control in which the VCT phase is feedback-controlled to the target VCT phase, the applicant of the present invention has detected that the lock pin protrudes and sticks abnormally based on the controllable range of the VCT phase. ) Research on abnormal diagnosis to determine the presence or absence of). However, during lock control that controls the lock pin to protrude and lock the VCT phase at the intermediate lock phase, the lock pin retracts and sticks abnormally (the lock pin sticks at the retracted position and does not protrude normally). In the above-described abnormality diagnosis (abnormality diagnosis for detecting lock pin protrusion / fixation abnormality during phase control), there is a drawback that the lock pin retraction / fixation abnormality cannot be detected during lock control.

  In addition, when the lock pin retracting and fixing abnormality occurs, the VCT phase cannot be locked at the intermediate lock phase during the lock control, and the VCT phase fluctuation due to the cam shaft torque occurs during the lock control (the fluctuation width of the VCT phase). Is larger than when the lock pin is normal). Therefore, it is conceivable to detect the VCT phase fluctuation due to the camshaft torque during the lock control to diagnose the lock pin abnormality. However, the conventional general cam angle sensor ensures the accuracy of detecting the VCT phase. Therefore, since the cam angle signal for detecting the VCT phase is set to be output at a timing that is hardly affected by the VCT phase fluctuation due to the camshaft torque, the VCT phase fluctuation due to the camshaft torque is set. Cannot be detected with high accuracy.

  Therefore, the problem to be solved by the present invention is to provide an abnormality diagnosis device for a variable valve timing control system capable of accurately detecting a VCT phase fluctuation due to camshaft torque and performing lock pin abnormality diagnosis during lock control. Is to provide.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a hydraulically driven variable valve that adjusts the valve timing by changing the rotational phase of the camshaft (hereinafter referred to as “VCT phase”) with respect to the crankshaft of the internal combustion engine. Variable valve timing control comprising a timing device, a lock pin for locking the VCT phase with an intermediate lock phase located within the adjustable range, and a hydraulic control valve for controlling the hydraulic pressure for driving the variable valve timing device and the lock pin In a system abnormality diagnosis device, a cam angle signal (hereinafter referred to as a “phase detection signal”) for detecting a VCT phase is output, and at the output timing different from the output timing of the phase detection signal, A cam angle signal (hereinafter referred to as “phase shake detection signal”) for detecting a VCT phase shake is output. The swing width of the VCT phase obtained from the output signal of the cam angle signal output means during the lock control for controlling the hydraulic control valve so that the angle signal output means and the lock pin protrude to lock the VCT phase at the intermediate lock phase And an abnormality diagnosis means for determining whether there is an abnormality of the lock pin based on the above.

  In this configuration, since the phase deviation detection signal is output from the cam angle signal output means at an output timing different from the phase detection signal, the VCT phase based on the cam shaft torque is output based on the output signal of the cam angle signal output means. Can be accurately detected. Then, by determining whether or not there is an abnormality in the lock pin based on the fluctuation width of the VCT phase obtained from the output signal of the cam angle signal output means during the lock control, the lock pin is retracted and stuck abnormally (the lock pin during the lock control). Is detected at the retracted position and does not protrude normally).

  In this case, as in claim 2, the abnormality diagnosis means may determine that there is an abnormality in the lock pin when the fluctuation width of the VCT phase is larger than a predetermined abnormality determination value during the lock control. When the lock pin retraction and sticking abnormality occurs, the VCT phase cannot be locked at the intermediate lock phase during the lock control, and the VCT phase fluctuation due to the camshaft torque becomes larger during the lock control than when the lock pin is normal. For this reason, when the fluctuation width of the VCT phase is larger than the abnormality determination value during the lock control, it can be determined that the lock pin is abnormal.

  The present invention may be applied to a system having only one lock pin, but as a lock pin, the VCT phase is prevented from moving to an advance side with respect to the intermediate lock phase. For example, the present invention may be applied to a system including an advance angle limit pin for preventing the VCT phase from moving to a retard angle side with respect to the intermediate lock phase. In this way, it is possible to detect an abnormality in the advance angle limit pin or the retard angle limit pin.

  In this case, as described in claim 4, the abnormality diagnosing means sets at least one of a position where a VCT phase fluctuation occurs during lock control (hereinafter referred to as a “VCT phase fluctuation position”) and a VCT phase fluctuation width. Based on this, it is possible to distinguish between an abnormality in the advance limit pin and an abnormality in the retard limit pin. Because the VCT phase fluctuation position and the VCT phase fluctuation width differ between the case where the advance angle limiting pin retracting and fixing abnormality occurs and the case where the retard angle limiting pin is retracting and fixing abnormally, the VCT phase fluctuation is different. By monitoring the position and the fluctuation width of the VCT phase, it is possible to distinguish between the abnormality of the advance limit pin and the abnormality of the retard limit pin.

  Specifically, as in claim 5, the abnormality diagnosing means determines that the advance angle limit pin is abnormal when the VCT phase fluctuation position is on the advance side of the intermediate lock phase during the lock control, and the lock control. If the VCT phase shake position is on the retard side of the intermediate lock phase, it may be determined that the retard limit pin is abnormal.

  That is, when the retracting and fixing abnormality of the advance angle limit pin occurs, the VCT phase is allowed to move to the advance side with respect to the intermediate lock phase, and the VCT phase fluctuation occurs on the advance side with respect to the intermediate lock phase. Therefore, when the shake position of the VCT phase is more advanced than the intermediate lock phase, it can be determined that the advance limit pin is abnormal. On the other hand, when the retraction fixing abnormality of the retard limit pin occurs, the VCT phase is allowed to move to the retard side with respect to the intermediate lock phase, and the VCT phase fluctuation occurs on the retard side with respect to the intermediate lock phase. Therefore, when the shake position of the VCT phase is on the retard side with respect to the intermediate lock phase, it can be determined that the retard limit pin is abnormal.

  Alternatively, the abnormality diagnosing means determines that the advance angle limit pin is abnormal when the fluctuation width of the VCT phase corresponds to the width of the limit range of the VCT phase by the delay angle limit pin during the lock control. Then, it may be determined that the delay angle limit pin is abnormal when the fluctuation width of the VCT phase corresponds to the width of the VCT phase limit range by the advance angle limit pin during the lock control.

  In other words, when the retraction / adhesion abnormality of the advance angle limit pin occurs, the movable range of the VCT phase is limited only by the delay angle limit pin, and the fluctuation of the VCT phase is within the limit range of the VCT phase by the delay angle limit pin. Therefore, when the fluctuation width of the VCT phase corresponds to the width of the VCT phase limit range by the retard limit pin, it can be determined that the advance limit pin is abnormal. On the other hand, when the retracting and fixing abnormality of the retard limit pin occurs, the movable range of the VCT phase is limited only by the advance limit pin, and the fluctuation of the VCT phase is within the limit range of the VCT phase by the advance limit pin. Therefore, when the fluctuation width of the VCT phase corresponds to the width of the limit range of the VCT phase by the advance limit pin, it can be determined that the delay limit pin is abnormal.

  According to a seventh aspect of the present invention, the cam angle signal output means may output the phase shake detection signal at both the timing at which the VCT phase is advanced and the timing at which it is retarded by the torque of the cam shaft. In this case, the advance side phase shake detection signal output at the timing when the VCT phase is advanced by the camshaft torque and the delay angle output at the timing when the VCT phase is retarded by the camshaft torque. Based on the phase shake detection signal on the side, the VCT phase shake due to the camshaft torque can be accurately detected.

  Alternatively, the cam angle signal output means outputs the phase detection signal at a timing when the VCT phase is advanced by the cam shaft torque, and at a timing at which the VCT phase is retarded by the cam shaft torque. A phase shake detection signal may be output. In this way, based on the phase detection signal output at the timing when the VCT phase is advanced by the camshaft torque and the phase shake detection signal output at the timing when the VCT phase is retarded by the camshaft torque. Thus, the VCT phase fluctuation due to the camshaft torque can be detected with high accuracy.

  According to a ninth aspect of the present invention, the cam angle signal output means outputs a phase detection signal at a timing when the VCT phase is retarded by the camshaft torque, and a phase at the timing when the VCT phase is advanced by the camshaft torque. A shake detection signal may be output. In this way, based on the phase detection signal output when the VCT phase is retarded by the camshaft torque and the phase shake detection signal output when the VCT phase is advanced by the camshaft torque. Thus, the VCT phase fluctuation due to the camshaft torque can be detected with high accuracy.

FIG. 1 is a diagram showing a schematic configuration of the entire control system in Embodiment 1 of the present invention. FIG. 2 is a longitudinal side view for explaining the configuration of the variable valve timing device and the hydraulic control circuit. FIG. 3 is a longitudinal front view of the variable valve timing device. 4A is a cross-sectional view of the intermediate lock mechanism showing the unlocked state, and FIG. 4B is a cross-sectional view of the intermediate lock mechanism showing the locked state. FIG. 5 is a diagram for explaining the control characteristics of the variable valve timing device. FIG. 6A is a cross-sectional view of the intermediate lock mechanism showing the state of the advance angle limiting pin when it is retracted and stuck abnormally, and FIG. 6B is the intermediate lock mechanism showing the state of the retard angle limit pin when it is retracted and stuck abnormally. FIG. FIG. 7 is a time chart showing the VCT phase fluctuation due to the intake camshaft torque and the behavior of the conventional cam angle signal. FIG. 8 is a time chart illustrating a method for outputting the phase detection signal and the phase shake detection signal according to the first embodiment. FIG. 9 is a diagram illustrating a schematic configuration of the signal rotor according to the first embodiment. FIG. 10 is a flowchart illustrating the processing flow of the abnormality diagnosis routine according to the first embodiment. FIG. 11 is a flowchart illustrating the process flow of the abnormal pin determination routine according to the first embodiment. FIG. 12 is a flowchart illustrating the process flow of the abnormal pin determination routine according to the second embodiment. FIG. 13 is a time chart illustrating a method for outputting a phase detection signal and a phase shake detection signal according to the third embodiment. FIG. 14 is a diagram illustrating a schematic configuration of a signal rotor according to the third embodiment. FIG. 15 is a flowchart illustrating the processing flow of the abnormality diagnosis routine according to the third embodiment. FIG. 16 is a time chart illustrating a method for outputting a phase detection signal and a phase shake detection signal according to the fourth embodiment. FIG. 17 is a flowchart for explaining the flow of processing of the abnormality diagnosis routine of the fourth embodiment.

  Hereinafter, several embodiments in which the mode for carrying out the present invention is applied to a variable valve timing apparatus for an intake valve will be described.

A first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, in an engine 11 that is an internal combustion engine, power from a crankshaft 12 is transmitted to an intake side camshaft 16 and an exhaust side camshaft 17 via sprockets 14 and 15 by a timing chain 13. It is like that. However, the intake side camshaft 16 is provided with a variable valve timing device 18 (VCT) that adjusts the advance amount (VCT phase) of the intake side camshaft 16 with respect to the crankshaft 12.

  A cam angle sensor 19 (cam angle signal output means) for outputting a cam angle signal pulse at a predetermined cam angle is installed on the outer peripheral side of the intake side cam shaft 16, and on the outer peripheral side of the crank shaft 12. Is provided with a crank angle sensor 20 that outputs a pulse of a crank angle signal at every predetermined crank angle. Output signals from the cam angle sensor 19 and the crank angle sensor 20 are input to the engine control circuit 21. The engine control circuit 21 calculates the actual valve timing (actual VCT phase) of the intake valve based on the phase difference between the output signal pulses of the cam angle sensor 19 and the crank angle sensor 20, and outputs the output pulse of the crank angle sensor 20. The engine speed is calculated based on the frequency (pulse interval). Further, output signals of various sensors (intake pressure sensor 22, cooling water temperature sensor 23, throttle sensor 24, etc.) for detecting the engine operating state are input to the engine control circuit 21.

  The engine control circuit 21 performs fuel injection control and ignition control according to the engine operating state detected by the various sensors, and also performs variable valve timing control (phase feedback control), and actual valve timing (actual VCT of the intake valve). The hydraulic pressure for driving the variable valve timing device 18 is feedback-controlled so that the phase) matches the target valve timing (target VCT phase).

Next, the configuration of the variable valve timing device 18 (VCT) 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 via the timing chain 13, and the sprocket 14 and the housing 31 rotate in synchronization with the crankshaft 12. On the other hand, a rotor 35 is fastened and fixed to one end of the intake side camshaft 16 with a bolt 37. The rotor 35 is housed in the housing 31 so as to be relatively rotatable.

  As shown in FIG. 3, a plurality of vane storage chambers 40 are formed inside the housing 31, and each vane storage chamber 40 is retarded from the advance chamber 42 by the vane 41 formed on the outer peripheral portion of the rotor 35. It is partitioned into a chamber 43. At both sides of at least one vane 41, a stopper portion 56 is formed that restricts the relative rotation range of the rotor 35 (vane 41) with respect to the housing 31, and the actual VCT phase (cam shaft phase) is adjusted by the stopper portion 56. The most retarded angle phase and the most advanced angle phase of the possible range are regulated.

  The variable valve timing device 18 is provided with an intermediate lock mechanism 50 that locks the VCT phase with an intermediate lock phase located approximately in the middle of the adjustable range. The configuration of the intermediate lock mechanism 50 will be described. Any one or a plurality of vanes 41 are provided with lock pin accommodation holes 57A and 57B (see FIG. 4). As the lock pin for locking relative rotation with the rotor 35 (vane 41), an advance angle limiting pin 58A is accommodated so as to protrude, and the other lock pin accommodation hole 57B accommodates the housing 31 and the rotor 35 (vane 41). As a lock pin for locking relative rotation with respect to, a retard angle limiting pin 58B is housed so as to protrude.

  As shown in FIG. 4B, each lock pin 58A, 58B (advance limit pin 58A and retard limit pin 58B) protrudes toward the sprocket 14 and fits into the lock holes 59A, 59B of the sprocket 14, The VCT phase is locked at the intermediate lock phase. At this time, the advance angle limit pin 58A prevents the VCT phase from moving toward the advance side with respect to the intermediate lock phase, and the retard angle limit pin 58B prevents the VCT phase from moving toward the retard side with respect to the intermediate lock phase. Be blocked. This intermediate lock phase is set to a phase suitable for starting the engine 11. The lock holes 59A and 59B may be provided in the housing 31.

  The lock hole 59A of the advance angle limit pin 58A is formed so as to extend from the intermediate lock phase to a predetermined phase on the retard side (for example, a phase on the retard side of 5 ° C. from the intermediate lock phase). By fitting in the lock hole 59A, the movable range of the VCT phase is limited to a range from the intermediate lock phase to a predetermined phase on the retard side, and the VCT phase moves to the advance side with respect to the intermediate lock phase. It has been stopped.

  On the other hand, the lock hole 59B of the retard limit pin 58B is formed to extend from the intermediate lock phase to a predetermined phase on the advance side (for example, a phase on the advance side of 10 ° C. from the intermediate lock phase). By fitting 58B into the lock hole 59B, the movable range of the VCT phase is limited to a range from the intermediate lock phase to a predetermined phase on the advance side, and the VCT phase is on the retard side with respect to the intermediate lock phase. It is prevented from moving.

  Each lock pin 58A, 58B (advance limit pin 58A and retard limit pin 58B) is urged in the lock direction (protrusion direction) by springs 62A, 62B. Further, between the outer peripheral portions of the lock pins 58A and 58B and the lock pin receiving holes 57A and 57B, a lock release for controlling the hydraulic pressure for driving the lock pins 58A and 58B in the lock release direction (retraction direction). A hydraulic chamber is formed.

  In addition, the housing 31 is provided with a spring 55 such as a torsion coil spring as an urging means for assisting (assisting) the hydraulic pressure for relatively rotating the rotor 35 in the advance angle direction during advance angle control. In the variable valve timing device 18 for the intake valve, the torque of the intake side camshaft 16 acts in a direction that retards the VCT phase. Therefore, the spring 55 has a direction opposite to the torque direction of the intake side camshaft 16. Will be urged in the advance direction.

  In the first embodiment, the range in which the spring 55 acts is set to the range from the most retarded phase to immediately before the intermediate lock phase, and the lock is assumed assuming fail-safe at restart after abnormal stop such as engine stall. When the pins 58A and 58B (advance limit pin 58A and retard limit pin 58B) are disengaged from the lock holes 59A and 59B, the starter (not shown) is started in the actual VCT phase that is retarded from the intermediate lock phase. During the cranking operation, the lock pins 58A and 58B are fitted into the lock holes 59A and 59B by assisting the advance operation of advancing the actual VCT phase from the retard side to the intermediate lock phase by the spring force of the spring 55. It can be locked.

  On the other hand, when the engine is started with an actual VCT phase that is more advanced than the intermediate lock phase, the torque of the intake camshaft 16 acts in the retarded direction during cranking, and therefore the actual VCT is increased by the torque of the intake camshaft 16. The lock pins 58A and 58B can be fitted into the lock holes 59A and 59B to be locked by retarding the phase from the advance side to the intermediate lock phase.

  Further, in the first embodiment, the rotor 35 is formed with a communication passage (not shown) for communicating the advance chamber 42 and the retard chamber 43, and as shown in FIG. In the unlocked state in which the pins 58A and 58B are extracted from the lock holes 59A and 59B, the on-off valves 63A and 63B move in the valve closing direction, and the communication path between the advance chamber 42 and the retard chamber 43 Is kept shut off. On the other hand, as shown in FIG. 4B, when the lock pins 58A and 58B protrude and are fitted in the lock holes 59A and 59B, the on-off valves 63A and 63B move in the valve opening direction to advance. The communication path between the corner chamber 42 and the retard chamber 43 is opened, and the oil can be kept in and out between the advance chamber 42 and the retard chamber 43.

  Further, as shown in FIGS. 1 and 2, the hydraulic control valve 25 controls the VCT phase of the variable valve timing device 18 and the hydraulic pressure for driving the lock pins 58A and 58B (the advance limit pin 58A and the retard limit pin 58B). Is composed of a hydraulic control valve that integrates a hydraulic control valve function for phase control that controls the hydraulic pressure that drives the VCT phase and a hydraulic control valve function for lock control that controls the hydraulic pressure that drives the lock pins 58A and 58B. The oil (operating oil) in the oil pan 27 is pumped up by the oil pump 28 driven by the power of the engine 11 and supplied to the hydraulic control valve 25.

  The hydraulic control valve 25 is constituted by, for example, an 8-port / four-position type spool valve, and, as shown in FIG. 5, the lock modes L1, L2, the advance mode are controlled according to the control duty (control amount) of the hydraulic control valve 25. The control area is divided into four control areas: angular mode A, holding mode H, and retarding mode R.

  In the control region of the lock modes L1 and L2, the oil supply oil passage to the lock release hydraulic chambers in the lock pin accommodation holes 57A and 57B is shut off, and the hydraulic pressure in the lock release hydraulic chambers in the lock pin accommodation holes 57A and 57B is obtained. The lock pins 58A and 58B (advance limit pin 58A and retard limit pin 58B) are protruded in the lock direction by the springs 62A and 62B.

  Further, the control region of the lock modes L1, L2 is retarded through the communication passage by opening the oil supply oil passage to the advance chamber 42 while projecting the lock pins 58A, 58B and supplying oil to the advance chamber 42. The control region of the oil filling mode L1 in which the chamber 43 is also filled with oil and the control region of the lock holding mode L2 in which the oil supply oil passage to the advance chamber 42 is blocked while the lock pins 58A and 58B are projected are divided. ing.

  In the control region of the advance angle mode A, the oil supply oil passage to the retard chamber 43 is shut off, the retard chamber 43 is opened to the drain, and the hydraulic pressure of the retard chamber 43 is released. In accordance with the control duty, the oil supply oil passage to the advance chamber 42 is opened and oil is supplied to the advance chamber 42 to change the hydraulic pressure in the advance chamber 42 to advance the actual VCT phase.

In the control region of the holding mode H, the oil supply oil passages of both the advance chamber 42 and the retard chamber 43 are shut off, and the oil pressures of both the chambers 42 and 43 are held so that the actual VCT phase does not move. .
In the control region of the retard angle mode R, the oil supply oil passage to the advance chamber 42 is shut off, the advance chamber 42 is opened to the drain, and the hydraulic pressure of the advance chamber 42 is released. In accordance with the control duty, the oil supply oil passage to the retard chamber 43 is opened, oil is supplied to the retard chamber 43, and the hydraulic pressure of the retard chamber 43 is changed to retard the actual VCT phase.

  In control areas other than the lock modes L1 and L2 (advance angle mode A, hold mode H, retard angle mode R), the oil supply oil passage to the lock release hydraulic chambers in the lock pin accommodation holes 57A and 57B is opened. The lock release hydraulic chambers in the lock pin receiving holes 57A and 57B are filled with oil to increase the hydraulic pressure of the lock release hydraulic chamber, and the lock pins 58A and 58B (advance limit pin 58A and retard limit pin are driven by the hydraulic pressure. 58B) is extracted from the lock holes 59A and 59B, and the lock pins 58A and 58B are unlocked.

  By the way, as shown in FIG. 6, the lock pins 58A and 58B (advance limit pin 58A and retard limit pin 58B) are protruded to lock the hydraulic control valve 25 so that the VCT phase is locked with the intermediate lock phase. During the control, there is a possibility that the lock pin 58A, 58B is retracted and stuck abnormally (the lock pin 58A, 58B is stuck at the retracted position and does not protrude normally), and the lock pin 58A, 58B is retracted and stuck abnormally. When this occurs, as shown in FIG. 7, the VCT phase cannot be locked at the intermediate lock phase during the lock control, and a VCT phase fluctuation due to the torque of the intake camshaft 16 occurs during the lock control (the VCT phase fluctuation). (The width becomes larger than when the lock pins 58A and 58B are normal).

  Therefore, it is conceivable to detect the VCT phase fluctuation due to the torque of the intake camshaft 16 during the lock control and perform an abnormality diagnosis of the lock pins 58A and 58B. However, as shown in FIG. The cam angle sensor outputs a cam angle signal for detecting the VCT phase at a timing that is hardly affected by the fluctuation of the VCT phase due to the torque of the intake side camshaft 16 in order to ensure the detection accuracy of the VCT phase. Therefore, there is a problem that the fluctuation of the VCT phase due to the torque of the intake camshaft 16 cannot be detected with high accuracy.

  As a countermeasure, the cam angle sensor 19 outputs a cam angle signal (hereinafter referred to as “phase detection signal”) for detecting the VCT phase, and at the output side different from the output timing of the phase detection signal. A cam angle signal (hereinafter referred to as “phase shake detection signal”) for detecting a VCT phase shake due to the torque of the camshaft 16 is set to be output. Thereby, based on the output signal of the cam angle sensor 19, it is possible to accurately detect the fluctuation of the VCT phase due to the torque of the intake camshaft 16.

  In the first embodiment, as shown in FIG. 8, the cam angle sensor 19 outputs a phase detection signal at a timing at which it is difficult to be affected by the fluctuation of the VCT phase due to the torque of the intake side camshaft 16, and the intake side camshaft. The phase shake detection signal is set to be output at both the timing at which the VCT phase is advanced and retarded by 16 torque.

  In this case, as shown in FIG. 9, a cam angle sensor 19 is installed facing the outer periphery of the signal rotor 64 attached to the intake side camshaft 16, and phase detection teeth 65 are provided on the outer periphery of the signal rotor 64. (Tooth for outputting a phase detection signal) and tooth 66 for detecting a phase shake (tooth for outputting a phase shake detection signal) are provided. The phase detection tooth 65 is disposed at a position corresponding to a timing that is not easily affected by the VCT phase fluctuation due to the torque of the intake side camshaft 16, and the phase fluctuation detection tooth 66 is the torque of the intake side camshaft 16. Therefore, the VCT phase is arranged at a position corresponding to the timing at which the VCT phase is advanced and retarded. Thereby, the phase detection signal and the phase shake detection signal are output from the cam angle sensor 19 in synchronization with the rotation of the signal rotor 64 (intake side camshaft 16). It should be noted that the circumferential length of the phase detection teeth 65 and the circumferential length of the phase shake detection teeth 66 are different dimensions, and the pulse width of the phase detection signal and the pulse width of the phase shake detection signal are different. You may make it.

  The engine control circuit 21 functions as abnormality diagnosis means in the claims by executing each abnormality diagnosis routine shown in FIGS. 10 and 11 to be described later. During the lock control, the intake side camshaft The phase shift detection signal on the advance side which is output at the timing when the VCT phase is advanced by the torque of 16 and the phase shift on the retard side which is output at the timing when the VCT phase is retarded by the torque of the intake side camshaft 16 Based on the detection signal, the fluctuation width of the VCT phase due to the torque of the intake camshaft 16 is detected, and the abnormality of the lock pins 58A and 58B depends on whether the fluctuation width of the VCT phase is larger than a predetermined abnormality determination value. The presence or absence of is determined.

  When the retraction and sticking abnormality of the lock pins 58A and 58B occurs, the VCT phase cannot be locked at the intermediate lock phase during the lock control, and the fluctuation width of the VCT phase due to the torque of the intake side camshaft 16 during the lock control becomes the lock pin 58A. , 58B is larger than normal, so that it can be determined that there is an abnormality in the lock pins 58A, 58B when the fluctuation width of the VCT phase is larger than the abnormality determination value during the lock control.

  Further, when it is determined that there is an abnormality in the lock pins 58A and 58B during the lock control, whether or not the VCT phase shake position (position where the VCT phase shake occurs) is on the more advanced side than the intermediate lock phase. When the VCT phase shake position is on the advance side of the intermediate lock phase, it is determined that the advance angle limit pin 58A is abnormal (withdrawal sticking abnormality), and the VCT phase shake position is later than the intermediate lock phase. In the case of the corner side, it is determined that the retardation limiting pin 58B is abnormal (retraction sticking abnormality).

  That is, as shown in FIG. 6A, when the retraction fixing abnormality of the advance angle limiting pin 58A occurs, the VCT phase is allowed to move to the advance side with respect to the intermediate lock phase. Since the VCT phase fluctuation occurs on the advance side, it can be determined that the advance limit pin 58A is abnormal (withdrawal sticking abnormality) when the VCT phase shake position is on the advanced side with respect to the intermediate lock phase. .

On the other hand, as shown in FIG. 6B, when the retracting and fixing abnormality of the retard limit pin 58B occurs, the VCT phase is allowed to move to the retard side with respect to the intermediate lock phase, so Since the VCT phase fluctuation occurs on the retard side, it can be determined that the retard limit pin 58B is abnormal (withdrawal sticking abnormality) when the VCT phase shake position is on the retard side with respect to the intermediate lock phase. .
The processing contents of the routines for abnormality diagnosis shown in FIGS. 10 and 11 executed by the engine control circuit 21 will be described below.

[Abnormal diagnosis routine]
The abnormality diagnosis routine shown in FIG. 10 is repeatedly executed at a predetermined cycle while the engine control circuit 21 is powered on. When this routine is started, first, at step 101, whether or not the abnormality diagnosis execution condition for the lock pins 58A and 58B is satisfied is determined that the lock control is being performed, the cam angle sensor 19 and the crank angle sensor 20 Judgment is made based on whether all conditions such as normality are satisfied.

If it is determined in step 101 that the abnormality diagnosis execution condition is not satisfied, this routine is terminated without performing the processing relating to abnormality diagnosis in and after step 102.
On the other hand, if it is determined in step 101 that the abnormality diagnosis execution condition is satisfied, processing relating to abnormality diagnosis in and after step 102 is executed as follows. First, in step 102, based on the output signal of the crank angle sensor 20 and the retarded phase fluctuation detection signal output from the cam angle sensor 19 at the timing at which the VCT phase is retarded by the torque of the intake camshaft 16. Thus, the phase on the retarded side of the VCT phase fluctuation due to the torque of the intake camshaft 16 (the VCT phase at the output timing of the phase deviation detection signal on the retarded side) is calculated.

  Thereafter, the process proceeds to step 103, where the output signal of the crank angle sensor 20 and the advance side phase fluctuation detection signal output from the cam angle sensor 19 at the timing when the VCT phase advances by the torque of the intake side camshaft 16 Based on the above, the advance side of the VCT phase fluctuation due to the torque of the intake camshaft 16 (the VCT phase at the output timing of the advance side phase shake detection signal) is calculated.

Thereafter, the process proceeds to step 104, and the phase difference between the phase on the advance side of the VCT phase fluctuation and the phase on the retard side of the VCT phase fluctuation is calculated as the fluctuation width of the VCT phase.
Swing width = Phase on the advance side-Phase on the retard side

  Thereafter, the process proceeds to step 105, in which it is determined whether or not the fluctuation width of the VCT phase is larger than a predetermined abnormality determination value. If it is determined in step 105 that the VCT phase fluctuation width is equal to or smaller than the abnormality determination value, the process proceeds to step 106 and it is determined that the lock pins 58A and 58B are not abnormal (normal).

  On the other hand, if it is determined in step 105 that the VCT phase fluctuation is larger than the abnormality determination value, the process proceeds to step 107, and after determining that there is an abnormality in the lock pins 58A and 58B, step 108 is performed. Then, an abnormal pin determination routine of FIG. 11 described later is executed to distinguish between the abnormality of the advance angle limiting pin 58A and the abnormality of the retard angle limiting pin 58B.

[Abnormal pin determination routine]
The abnormal pin determination routine shown in FIG. 11 is a subroutine executed in step 108 of the abnormality diagnosis routine of FIG. When this routine is started, first, in step 201, it is determined whether or not the VCT phase fluctuation position (position where the VCT phase fluctuation occurs) is on the more advanced side than the intermediate lock phase. The determination is made based on whether or not the center position of the swing width is on the advance side with respect to the intermediate lock phase.

  If it is determined in this step 201 that the VCT phase shake position is on the advance side with respect to the intermediate lock phase, the process proceeds to step 202, where it is determined that the advance angle limiting pin 58A is abnormal (retraction sticking abnormality).

  On the other hand, if it is determined in step 201 that the VCT phase shake position is not on the advance side of the intermediate lock phase, it is determined that the VCT phase shake position is on the retard side of the intermediate lock phase. Then, the process proceeds to step 203, and it is determined that the retardation limit pin 58B is abnormal (retraction sticking abnormality).

  In the first embodiment described above, since the phase shake detection signal is output from the cam angle sensor 19 at an output timing different from the phase detection signal, the intake side camshaft is based on the output signal of the cam angle sensor 19. Thus, the VCT phase fluctuation due to the torque of 16 can be accurately detected, and the fluctuation of the VCT phase obtained from the output signal of the cam angle sensor 19 during the lock control is compared with the abnormality determination, and the lock pins 58A and 58B are abnormal. Since the presence / absence of the lock pin is determined, it is possible to detect the retraction and sticking abnormality of the lock pins 58A and 58B during the lock control.

  Further, in the first embodiment, when it is determined that there is an abnormality in the lock pins 58A and 58B during the lock control, it is determined whether or not the shake position of the VCT phase is an advance side with respect to the intermediate lock phase. When the VCT phase shake position is on the advance side with respect to the intermediate lock phase, it is determined that the advance angle limit pin 58A is abnormal (withdrawal sticking abnormality), and the VCT phase shake position is on the retard side with respect to the intermediate lock phase. Since it is determined that the delay angle limit pin 58B is abnormal (withdrawal sticking error), the advance angle limit pin 58A and the delay angle limit pin 58B can be distinguished and determined.

  Further, in the first embodiment, the phase shake detection signal is output at both the timing at which the VCT phase is advanced and retarded by the torque at the intake side camshaft 16, so the torque at the intake side camshaft 16 is increased. The phase shift detection signal on the advance side that is output at the timing at which the VCT phase is advanced due to the above, and the phase shift detection signal on the retard side that is output at the timing at which the VCT phase is retarded by the torque of the intake camshaft 16 Based on the above, it is possible to accurately detect the fluctuation of the VCT phase due to the torque of the intake camshaft 16.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the second embodiment, the engine control circuit 21 executes an abnormal pin determination routine shown in FIG. 12, which will be described later, and if it is determined that there is an abnormality in the lock pins 58A and 58B during the lock control, the VCT phase fluctuations. It is determined whether or not the width corresponds to the width of the VCT phase limit range by the retard limit pin 58B, and the process proceeds when the fluctuation width of the VCT phase corresponds to the width of the VCT phase limit range by the retard limit pin 58B. It is determined that the angle limit pin 58A is abnormal (withdrawal sticking abnormality), and the delay limit pin 58B is abnormal (withdrawal sticking abnormality) when the fluctuation width of the VCT phase corresponds to the width of the VCT phase restriction range by the advance angle restricting pin 58A. ).

  That is, as shown in FIG. 6A, when the retraction fixing abnormality of the advance angle limit pin 58A occurs, the movable range of the VCT phase is limited only by the delay angle limit pin 58B, and the retard angle limit is set. Since the VCT phase fluctuation occurs in the VCT phase limit range by the pin 58B, when the VCT phase fluctuation width corresponds to the width of the VCT phase limit range by the retardation limit pin 58B (for example, 10 ° C.), It can be determined that the advance angle limiting pin 58A is abnormal (withdrawal sticking abnormality).

  On the other hand, when the retracting and fixing abnormality of the retard limit pin 58B occurs, the movable range of the VCT phase is limited only by the advance limit pin 58A, and the VCT phase is limited by the advance angle limit pin 58A. Since a phase fluctuation occurs, if the fluctuation width of the VCT phase corresponds to the width of the VCT phase restriction range (for example, 5 ° C.) by the advance angle restriction pin 58A, the delay angle restriction pin 58B is abnormal (withdrawal sticking). Abnormal).

  The routine of FIG. 12 is obtained by changing the process of step 201 of the routine of FIG. 11 described in the first embodiment to the process of step 201a, and the processes of other steps are the same as those of FIG.

  In the abnormal pin determination routine shown in FIG. 12, first, in step 201a, it is determined whether or not the fluctuation width of the VCT phase corresponds to the width of the VCT phase limit range (for example, 10 ° C. A) by the retard limit pin 58B. Then, it is determined whether or not the fluctuation width of the VCT phase is larger than a predetermined threshold (for example, 8 ° C. A).

  If it is determined in step 201a that the VCT phase fluctuation width corresponds to the width of the VCT phase limit range (for example, 10 ° C. A) by the retard limit pin 58B, the process proceeds to step 202 and the advance angle limit pin 58A. It is determined that there is an abnormality (retraction sticking abnormality).

  On the other hand, if it is determined in step 201a that the VCT phase fluctuation width does not correspond to the width of the VCT phase restriction range by the retard limit pin 58B, the VCT phase fluctuation width is VCT by the advance angle restriction pin 58A. It is determined that the width corresponds to the width of the phase limit range (for example, 5 ° C. A), and the process proceeds to step 203, where it is determined that the retardation limit pin 58B is abnormal (retraction sticking abnormality).

  In the second embodiment described above, when it is determined that there is an abnormality in the lock pins 58A and 58B during the lock control, the VCT phase fluctuation width corresponds to the width of the VCT phase limit range by the retard limit pin 58B. When the VCT phase fluctuation width corresponds to the width of the VCT phase limit range by the retard limit pin 58B, it is determined that the advance angle limit pin 58A is abnormal (withdrawal sticking error), and the VCT phase Is determined to be an abnormality of the retard limit pin 58B (retraction sticking abnormality) when the fluctuation width corresponds to the width of the limit range of the VCT phase by the advance limit pin 58A. It is possible to distinguish and determine the abnormality of the retard limit pin 58B.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the third embodiment, as shown in FIG. 13, the cam angle sensor 19 outputs a phase detection signal at the timing when the VCT phase advances by the torque of the intake side camshaft 16, and the torque of the intake side camshaft 16 The phase shake detection signal is set to be output at a timing at which the VCT phase is retarded.

  In this case, as shown in FIG. 14A, phase detection teeth 68 and phase shake detection teeth 69 are provided on the outer periphery of the signal rotor 67, and the phase detection teeth 68 are formed on the intake side cam. The VCT phase is positioned at a position corresponding to the timing at which the VCT phase is advanced by the torque of the shaft 16, and the phase shake detection tooth 69 is positioned at a position corresponding to the timing at which the VCT phase is retarded by the torque of the intake camshaft 16. Has been. It should be noted that the circumferential length of the phase detection teeth 68 and the circumferential length of the phase shake detection teeth 69 are different dimensions, and the pulse width of the phase detection signal and the pulse width of the phase shake detection signal are different. You may make it.

  Alternatively, as shown in FIG. 14B, teeth 71 having a relatively long circumferential length are provided on the outer periphery of the signal rotor 70 and synchronized with the rotation of the signal rotor 70 (intake side camshaft 16). Thus, the rising edge (or falling edge) of the pulse signal output from the cam angle sensor 19 is used as the phase detection signal, and the falling edge (or rising edge) of the pulse signal is used as the phase shake detection signal. May be.

  Then, by executing an abnormality diagnosis routine of FIG. 15 to be described later by the engine control circuit 21, a phase detection signal output at a timing at which the VCT phase is advanced by the torque of the intake side camshaft 16 during the lock control, Based on the phase fluctuation detection signal output at the timing at which the VCT phase is retarded by the torque of the intake camshaft 16, the fluctuation width of the VCT phase due to the torque of the intake camshaft 16 is detected. Whether or not there is an abnormality in the lock pins 58A and 58B is determined depending on whether or not the width is larger than a predetermined abnormality determination value.

  The routine of FIG. 15 is obtained by changing the processing of steps 102 and 103 of the routine of FIG. 10 described in the first embodiment to the processing of steps 102a and 103a, and the processing of each other step is the same as FIG. It is.

  In the abnormality diagnosis routine shown in FIG. 15, when it is determined in step 101 that the abnormality diagnosis execution condition is satisfied, the process proceeds to step 102 a and the output signal of the crank angle sensor 20 and the torque of the intake camshaft 16 are processed. Based on the phase shake detection signal output from the cam angle sensor 19 at the timing at which the VCT phase is retarded by this, the phase on the retard side of the VCT phase shake due to the torque of the intake camshaft 16 (the phase shake detection signal VCT phase at output timing) is calculated.

  Thereafter, the routine proceeds to step 103a, where the intake air intake is determined based on the output signal of the crank angle sensor 20 and the phase detection signal output from the cam angle sensor 19 at the timing when the VCT phase is advanced by the torque of the intake side camshaft 16. The phase on the advance side of the VCT phase fluctuation due to the torque of the side cam shaft 16 (VCT phase at the output timing of the phase detection signal) is calculated.

  Thereafter, after calculating the phase difference between the phase on the advance side of the VCT phase fluctuation and the phase on the retard side of the VCT phase fluctuation as the VCT phase fluctuation width, the VCT phase fluctuation width is a predetermined abnormality. It is determined whether it is larger than the determination value, and when it is determined that the fluctuation width of the VCT phase is equal to or less than the abnormality determination value, it is determined that there is no abnormality (normal) in the lock pins 58A and 58B (steps 104 to 104). 106).

  On the other hand, when it is determined that the fluctuation width of the VCT phase is larger than the abnormality determination value, the process proceeds to step 107, and after determining that the lock pins 58A and 58B are abnormal, the process proceeds to step 108 and described above. The abnormal pin determination routine of FIG. 11 or FIG. 12 is executed to distinguish between the abnormality of the advance angle limiting pin 58A and the abnormality of the retard angle limiting pin 58B.

  In the third embodiment described above, the phase detection signal is output at the timing when the VCT phase is advanced by the torque of the intake side camshaft 16, and the phase fluctuation is generated at the timing when the VCT phase is retarded by the torque of the intake side camshaft 16. Since the detection signal is output, the phase detection signal output when the VCT phase is advanced by the torque of the intake camshaft 16 and the timing when the VCT phase is delayed by the torque of the intake camshaft 16. Based on the output phase fluctuation detection signal, it is possible to accurately detect the fluctuation of the VCT phase due to the torque of the intake camshaft 16.

  Next, Embodiment 4 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as in the third embodiment will be omitted or simplified, and different parts from the third embodiment will be mainly described.

  In the fourth embodiment, as shown in FIG. 16, the cam angle sensor 19 outputs a phase detection signal at a timing when the VCT phase is retarded by the torque of the intake side camshaft 16, and the torque of the intake side camshaft 16 The phase shake detection signal is set to be output at the timing when the VCT phase advances.

  Then, by executing an abnormality diagnosis routine of FIG. 17 to be described later by the engine control circuit 21, a phase detection signal output at a timing at which the VCT phase is retarded by the torque of the intake side camshaft 16 during the lock control, Based on the phase fluctuation detection signal output at the timing when the VCT phase is advanced by the torque of the intake camshaft 16, the fluctuation width of the VCT phase due to the torque of the intake camshaft 16 is detected. Whether or not there is an abnormality in the lock pins 58A and 58B is determined depending on whether or not the width is larger than a predetermined abnormality determination value.

  The routine of FIG. 17 is obtained by changing the processing of steps 102 and 103 of the routine of FIG. 10 described in the first embodiment to the processing of steps 102b and 103b, and the processing of other steps is the same as that of FIG. It is.

  In the abnormality diagnosis routine shown in FIG. 17, when it is determined in step 101 that the abnormality diagnosis execution condition is satisfied, the process proceeds to step 102 b and the output signal of the crank angle sensor 20 and the torque of the intake camshaft 16 are determined. Based on the phase detection signal output from the cam angle sensor 19 at the timing at which the VCT phase is retarded by this, the phase on the retarded side of the VCT phase fluctuation due to the torque of the intake camshaft 16 (phase detection signal output timing) VCT phase) is calculated.

  Thereafter, the process proceeds to Step 103b, and based on the output signal of the crank angle sensor 20 and the phase fluctuation detection signal output from the cam angle sensor 19 at the timing when the VCT phase is advanced by the torque of the intake side camshaft 16, The phase on the advance side of the VCT phase fluctuation due to the torque of the intake camshaft 16 (the VCT phase at the output timing of the phase fluctuation detection signal) is calculated.

  Thereafter, after calculating the phase difference between the phase on the advance side of the VCT phase fluctuation and the phase on the retard side of the VCT phase fluctuation as the VCT phase fluctuation width, the VCT phase fluctuation width is a predetermined abnormality. It is determined whether it is larger than the determination value, and when it is determined that the fluctuation width of the VCT phase is equal to or less than the abnormality determination value, it is determined that there is no abnormality (normal) in the lock pins 58A and 58B (steps 104 to 104). 106).

  On the other hand, when it is determined that the fluctuation width of the VCT phase is larger than the abnormality determination value, the process proceeds to step 107, and after determining that the lock pins 58A and 58B are abnormal, the process proceeds to step 108 and described above. The abnormal pin determination routine of FIG. 11 or FIG. 12 is executed to distinguish between the abnormality of the advance angle limiting pin 58A and the abnormality of the retard angle limiting pin 58B.

  In the fourth embodiment described above, the phase detection signal is output at the timing when the VCT phase is retarded by the torque of the intake camshaft 16, and the phase fluctuation is generated at the timing when the VCT phase is advanced by the torque of the intake camshaft 16. Since the detection signal is output, the phase detection signal that is output when the VCT phase is retarded by the torque of the intake cam shaft 16 and the timing that the VCT phase is advanced by the torque of the intake cam shaft 16 are output. Based on the output phase fluctuation detection signal, it is possible to accurately detect the fluctuation of the VCT phase due to the torque of the intake camshaft 16.

  In each of the first to fourth embodiments, when it is determined that there is an abnormality in the lock pins 58A and 58B, the abnormality pin determination routine of FIG. 11 or FIG. The abnormality of the angle limit pin 58B is distinguished from that of the angle limit pin 58B, but the present invention is not limited to this, and an abnormality pin determination routine (a process for distinguishing between the abnormality of the advance angle limit pin 58A and the abnormality of the delay angle limit pin 58B) is omitted. You may do it.

  In each of the first to fourth embodiments, the present invention is applied to a system including the advance angle limiting pin 58A and the retard angle limiting pin 58B as lock pins. However, the present invention is not limited to this, and only one lock pin is used. The present invention may be applied to a system provided.

  Each of the first to fourth embodiments described above is an embodiment in which the present invention is applied to a variable valve timing device for an intake valve, but may be applied to a variable valve timing device for an exhaust valve. . When the present invention is applied to a variable valve timing device for an exhaust valve, the VCT phase control direction of the exhaust valve (the relationship between “advance angle” and “retard angle”) is opposite to the control direction of the VCT phase of the intake valve. Just do it.

  In addition, the present invention may be implemented with various changes 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 hydraulic control valve.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Crankshaft, 14 ... Sprocket, 16 ... Intake side camshaft, 17 ... Exhaust side camshaft, 18 ... Variable valve timing device, 19 ... Cam angle sensor (cam angle signal output means) 20 ... Crank angle sensor, 21 ... Engine control circuit (abnormality diagnosis means), 25 ... Hydraulic control valve, 28 ... Oil pump, 31 ... Housing, 35 ... Rotor, 41 ... Vane, 50 ... Intermediate lock mechanism, 57A, 57B ... Lock pin accommodation hole, 58A ... Advance angle limit pin (lock pin), 58B ... Delay angle limit pin (lock pin), 59A, 59B ... Lock hole,

Claims (9)

A hydraulically driven variable valve timing device that adjusts the valve timing by changing the rotational phase of the camshaft relative to the crankshaft of the internal combustion engine (hereinafter referred to as “VCT phase”), and an intermediate lock that positions the VCT phase within its adjustable range In an abnormality diagnosis device for a variable valve timing control system, comprising: a lock pin for locking with a phase; and a hydraulic control valve for controlling the hydraulic pressure for driving the variable valve timing device and the lock pin;
A cam angle signal (hereinafter referred to as “phase detection signal”) for detecting the VCT phase is output, and a VCT phase fluctuation due to the cam shaft torque is detected at an output timing different from the output timing of the phase detection signal. Cam angle signal output means for outputting a cam angle signal (hereinafter referred to as “phase shake detection signal”),
Based on the swing width of the VCT phase obtained from the output signal of the cam angle signal output means during the lock control for controlling the hydraulic control valve so that the lock pin protrudes and the VCT phase is locked at the intermediate lock phase. An abnormality diagnosis device for a variable valve timing control system, comprising: an abnormality diagnosis unit that determines whether there is an abnormality in the lock pin.   2. The variable valve timing according to claim 1, wherein the abnormality diagnosis unit determines that there is an abnormality in the lock pin when a fluctuation width of a VCT phase is larger than a predetermined abnormality determination value during the lock control. Control system abnormality diagnosis device.   As the lock pin, an advance angle limiting pin for preventing the VCT phase from moving toward the advance side with respect to the intermediate lock phase, and preventing the VCT phase from moving toward the retard side with respect to the intermediate lock phase. An abnormality diagnosing device for a variable valve timing control system according to claim 1 or 2, further comprising:   The abnormality diagnosing means is configured to detect the advance angle limiting pin based on at least one of a position where a VCT phase fluctuation occurs during the lock control (hereinafter referred to as a “VCT phase fluctuation position”) and a VCT phase fluctuation width. 4. The abnormality diagnosis device for a variable valve timing control system according to claim 3, further comprising means for distinguishing between an abnormality and an abnormality of the retard limit pin.   The abnormality diagnosing means determines that the advance limit pin is abnormal when the VCT phase shake position is on the advance side of the intermediate lock phase during the lock control, and the VCT phase shake position during the lock control. 5. The abnormality diagnosis device for a variable valve timing control system according to claim 4, wherein when the angle is more retarded than the intermediate lock phase, it is determined that the retard limit pin is malfunctioning.   The abnormality diagnosing means determines that the advance angle limit pin is abnormal when the fluctuation width of the VCT phase corresponds to the width of the VCT phase limit range by the retard limit pin during the lock control, and the lock control is in progress 5. The variable valve timing control according to claim 4, wherein when the VCT phase fluctuation width corresponds to a width of a VCT phase limit range by the advance angle limit pin, it is determined that the retardation limit pin is abnormal. System abnormality diagnosis device.   7. The cam angle signal output means outputs the phase shake detection signal at both a timing at which a VCT phase is advanced and a timing at which it is retarded by the torque of the cam shaft. An abnormality diagnosis device for a variable valve timing control system described in 1.   The cam angle signal output means outputs the phase detection signal when the VCT phase is advanced by the torque of the cam shaft, and outputs the phase shake detection signal when the VCT phase is delayed by the torque of the cam shaft. 7. The abnormality diagnosis device for a variable valve timing control system according to claim 1, wherein the abnormality diagnosis device outputs the abnormality.   The cam angle signal output means outputs the phase detection signal at a timing at which the VCT phase is retarded by the torque of the cam shaft, and outputs the phase shake detection signal at a timing at which the VCT phase is advanced by the torque of the cam shaft. 7. The abnormality diagnosis device for a variable valve timing control system according to claim 1, wherein the abnormality diagnosis device outputs the abnormality.

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