JP2007315382A - Diagnostic system for anomaly in vane-type variable valve timing control mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect at an early stage an anomaly in a drain selector valve and a check valve in a vane-type variable valve timing control mechanism provided with the check valve. <P>SOLUTION: Check valves 30, 31 are provided respectively to a hydraulic supply oil-path 28 for an advance chamber 18 and a hydraulic supply oil-path 29 for a delay angle chamber 19, and drain oil-paths 32, 33 bypassing the check valves 30, 31 respectively are provided in parallel with each other in hydraulic supply oil-paths 28, 29 of the lead angle chamber 18, the delay angle chamber 19. Drain selector valves 34, 35 are provided respectively to the drain oil-paths 32, 33. A drain selection-control function 38 for selecting the pressure oil for driving the drain selector valves 34, 35 is integrally provided to a hydraulic control valve 21 for controlling the oil pressure supplied to the chamber 18 and the chamber 19. On the basis whether or not a variation in a VCT displacement angle has exceeded a normal range in a specified period of time during a retention operation, it is determined whether an anomalous condition that the drain selector valves 34, 35, and/or check valves 30, 31 are left open, and kept unmovable or not. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a vane type variable valve timing adjustment in which a check valve for preventing a backflow of hydraulic oil from each hydraulic chamber is provided in each of a hydraulic supply oil passage in an advance chamber and a hydraulic supply oil passage in a retard chamber. The invention relates to a mechanism abnormality diagnosis device.

  In recent years, internal-combustion engines mounted on vehicles have adopted variable valve timing devices that vary the valve timing (cam shaft displacement angle) of intake valves and exhaust valves in order to improve output, reduce fuel consumption, and reduce exhaust emissions. Is increasing. For example, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2001-159330), a basic configuration of a vane type variable valve timing device includes a housing that rotates in synchronization with an engine crankshaft, and an intake valve (or The vane rotor connected to the cam shaft of the exhaust valve) is coaxially arranged, and a plurality of vane storage chambers formed in the housing are divided into an advance chamber and a retard chamber by vanes (blade portions) on the outer periphery side of the vane rotor. Partition. Then, by controlling the hydraulic pressure in each hydraulic chamber with a hydraulic control valve and rotating the vane rotor relative to the housing, the camshaft displacement angle (camshaft phase) with respect to the crankshaft is changed to change the valve timing. Variable control is performed.

  In such a vane type variable valve timing device, when opening and closing the intake valve and exhaust valve during engine operation, the fluctuation of the friction torque received by the camshaft from the intake valve and exhaust valve is transmitted to the vane rotor. Torque fluctuations in the retard direction and the advance direction act on the vane rotor. As a result, when the vane rotor receives torque fluctuations in the retarding direction, the hydraulic oil in the advance chamber receives pressure that is pushed out of the advance chambers, and when the vane rotor receives torque fluctuations in the advance direction, The hydraulic oil is subjected to pressure that is pushed out of the retard chamber. For this reason, in the low rotation region where the hydraulic pressure supplied from the hydraulic pressure supply source is low, even if it is attempted to advance the camshaft displacement angle by supplying hydraulic pressure to the advance chamber, as shown by the dotted line in FIG. Is pushed back in the retarded direction due to the torque fluctuation, and there is a problem that the response time until reaching the target displacement angle becomes long.

In order to solve this problem, as shown in Patent Document 2 (Japanese Patent Laid-Open No. 2003-106115), a check valve is provided in each of the hydraulic supply oil passage in the retard chamber and the hydraulic supply oil passage in the advance chamber, Even if the vane rotor is subjected to torque fluctuations, the check valve prevents the hydraulic oil from flowing backward from the retard chamber or advance chamber, and as shown by the solid line in FIG. It is considered to improve the responsiveness of the variable valve timing control by preventing it from returning in the direction opposite to the corner direction.
JP 2001-159330 A (pages 4 to 6 etc.) JP 2003-106115 A (first page, etc.)

  By the way, in the variable valve timing device of Patent Document 2, check valves are provided in the hydraulic pressure supply oil passages of the advance chamber and the hydraulic supply oil passages (hydraulic introduction lines) of the retard chamber, and the hydraulic pressure of each hydraulic chamber is set. A return line (hydraulic discharge line) that bypasses the check valve is provided in parallel in the supply oil path, and each hydraulic chamber returns to a hydraulic control valve (spool solenoid valve) that controls the hydraulic pressure supplied to each hydraulic chamber. The function as a line switching valve that opens and closes the line is integrated. By controlling the control current value of the hydraulic control valve, the hydraulic pressure supplied to each hydraulic chamber is controlled, and at the same time, the switching of opening / closing of the return line of each hydraulic chamber is controlled. When it is necessary to release the hydraulic pressure, the return line of the hydraulic chamber is opened so that the hydraulic pressure can be quickly released through the return line.

  However, in the variable valve timing device of Patent Document 2, the armature of the hydraulic control valve is driven by an electric variable force solenoid, and the total length in the cam shaft direction becomes long, so that the mountability is deteriorated. .

  Therefore, the applicant of the present invention is provided with a drain switching valve that is hydraulically driven in a drain oil passage that bypasses the check valve, and an electromagnetic hydraulic switching valve that switches the hydraulic pressure that drives each drain switching valve. A variable valve timing device is proposed. In this configuration, the drain switching valve can be reduced in size and electrical wiring to the drain switching valve is unnecessary, so the drain switching valve and the check valve can be assembled compactly in a narrow space inside the variable valve timing adjustment mechanism. Is possible. In addition, since it is not necessary to directly mount the hydraulic pressure switching valve and the hydraulic control valve for controlling the hydraulic pressure supplied to each hydraulic chamber of the variable valve timing device on the camshaft, the variable valve timing is higher than that of the above-mentioned Patent Document 2. There is an advantage that the mountability of the apparatus is improved. The applicant further improved the variable valve timing device, and switched the hydraulic pressure for driving each drain switching valve with one hydraulic control valve and controlled the hydraulic pressure supplied to each hydraulic chamber of the variable valve timing device. A variable valve timing device having a configuration that can be used has also been proposed.

  During the development process of such a variable valve timing mechanism, when it is operated for a long period of time, such as in an endurance test, the drain switching valve or the check valve may be trapped with foreign matter or the valve body may adhere to the drain switching valve. It has been found that there is a possibility that an abnormality may occur in which the check valve does not operate normally. In order to deteriorate the engine performance, it is necessary to detect such an abnormality as early as possible and notify the driver to promote repair.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an abnormality diagnosis device for a vane variable valve timing adjustment mechanism that can detect an abnormality in which a drain switching valve and a check valve do not operate normally at an early stage.

  To achieve the above object, according to the first aspect of the present invention, a plurality of vane storage chambers formed in a housing of a vane type variable valve timing adjusting mechanism are divided into an advance chamber and a retard chamber by the vanes, respectively. In each of the hydraulic chambers (the “hydraulic chamber” is the “advance chamber” and the “retard chamber”), the hydraulic supply fluid passage of the advance chamber and the retard chamber of the at least one vane storage chamber respectively. A check valve for preventing the backflow of hydraulic oil from each other), and a drain oil passage that bypasses the check valve is provided in parallel in the hydraulic supply oil passage of each hydraulic chamber, In the abnormality diagnosis device for a vane type variable valve timing adjustment mechanism, a drain switching valve that is driven by hydraulic pressure is provided in each drain oil passage, and a hydraulic switching valve that switches a hydraulic pressure that drives each drain switching valve is provided. During the holding operation for maintaining the displacement angle of the valve timing adjusting mechanism (hereinafter referred to as “VCT displacement angle”) at the target displacement angle, both the advance chamber side and the retard chamber side drain switching valves are closed to advance the advance chamber. The hydraulic switching valve is controlled so as to prevent the backflow of hydraulic oil from both hydraulic chambers by effectively functioning both the check valve on the side and the retard chamber side, and the hydraulic pressure in each hydraulic chamber is controlled. During the advance / retard operation in which the control current of the hydraulic control valve is controlled to a predetermined holding current and the VCT displacement angle is displaced in the advance direction or the retard direction, an advance chamber is generated according to the displacement direction. The hydraulic pressure control valve is controlled so that one of the non-return valves does not function by opening one of the drain switching valves on the side and the retard chamber side, and controlling the control current of the hydraulic control valve to By changing the hydraulic pressure in the hydraulic chamber, the VCT displacement angle is set to the target displacement angle. To displace Te. Then, the abnormality diagnosis means, during the holding operation, has an “open abnormality” occurred in which the drain switching valve and / or the check valve does not move based on the amount of change in the VCT displacement angle within a predetermined period? It is determined whether or not.

  During the holding operation, if both the advance angle chamber side and retard angle chamber side drain switching valves operate normally, both drain switching valves close, so if both check valves are normal, both reverse The backflow prevention function of the stop valve can be activated effectively. However, if an “open abnormality” that does not move while either drain switching valve (or check valve) is open, either The drain switching valve (or check valve) is fixed open. For this reason, if any one of the drain switching valves (or check valves) is abnormally open during the holding operation, the hydraulic pressure in the hydraulic chamber on the side where the abnormal opening occurs is reduced to the drain switching valve (or As a result of leakage through the check valve, the hydraulic pressure balance of both hydraulic chambers is lost, the VCT displacement angle cannot be held at a fixed position, and a variation in the VCT displacement angle increases. Focusing on this characteristic, the present invention determines whether or not there is an abnormal opening of the drain switching valve and / or the check valve based on the amount of change in the VCT displacement angle within a predetermined period during the holding operation. Thus, it is possible to detect an abnormal opening of the drain switching valve or the check valve early during engine operation.

  In this case, there are various methods for detecting the amount of change in the VCT displacement angle within the predetermined period during the holding operation. For example, as in claim 2, the VCT displacement angle immediately after the start of the holding operation and the predetermined amount are determined. A difference from the VCT displacement angle when the period elapses may be calculated, and the presence / absence of an abnormal opening of the drain switching valve and / or the check valve may be determined based on this difference. In this case, when the VCT displacement angle after the predetermined period has deviated from the VCT displacement angle immediately after the start of the holding operation is abnormally deviated in the retarded direction and abnormally deviated in the advance direction. Therefore, it is possible to distinguish and determine whether the drain switching valve (or check valve) is open abnormally on the advanced chamber side or the retarded chamber side. There is an advantage that it is possible to specify the location where the open abnormality occurs.

  For example, if the VCT displacement angle deviates significantly in the retard direction during the holding operation, the advance chamber side drain switching valve (or check valve) that applies hydraulic pressure to the vane in the advance direction opens. It can be determined that the hydraulic pressure in the advance chamber leaks through the drain switching valve (or check valve) and decreases. Also, if the VCT displacement angle deviates significantly in the advance direction during the holding operation, the retard chamber side drain switching valve (or check valve) that applies hydraulic pressure to the vane in the retard direction opens. It can be determined that the hydraulic pressure in the retarded chamber leaks through the drain switching valve (or check valve) and decreases.

  On the other hand, if both the advance angle chamber side and the retard angle chamber side drain switching valves (or check valves) are abnormally open, the holding operation is being performed (especially low supply pressure from the hydraulic supply source is low) During the holding operation in the region), the return of the VCT displacement angle due to the camshaft friction torque occurs in synchronization with the rotation of the camshaft. Therefore, during the holding operation, the VCT displacement angle synchronizes with the rotation of the camshaft. A phenomenon occurs in which vibration is relatively large alternately in the advance direction and the retard direction around the corner.

  In consideration of this characteristic, as in claim 3, the maximum and minimum values of the VCT displacement angle from immediately after the start of the holding operation until the predetermined period elapses are detected, and the difference between them is calculated. Based on this difference Then, it may be determined whether there is an abnormal opening of the drain switching valve and / or the check valve. In this case, since the maximum width of the vibration range of the VCT displacement angle is known from the difference between the maximum value and the minimum value of the VCT displacement angle, the difference between the maximum value and the minimum value of the VCT displacement angle (maximum width of the vibration range) is normal. If it exceeds the range, it can be determined that the drain switching valve and / or the check valve on both the advance angle chamber side and the retard angle chamber side are abnormally opened.

  According to a fourth aspect of the present invention, the maximum value and the minimum value of the VCT displacement angle from the start of the holding operation until the predetermined period elapses are detected, and the deviation between the target displacement angle and the maximum value during the holding operation A deviation between the target displacement angle and the minimum value may be calculated, and based on these two deviations, it may be determined whether there is an abnormal opening of the drain switching valve and / or the check valve. In this way, the change amount (deviation) in the advance direction of the VCT displacement angle is compared with the change amount (deviation) in the retard direction based on the target displacement angle, and the change amount (deviation) in both directions is obtained. If it is the same level, it can be judged that the drain switching valve (or check valve) on both the advance angle chamber side and the retard angle chamber side is abnormally open, and only the change (deviation) on one side is abnormal. If it is larger, it can be determined that only the drain switching valve (or check valve) on one side is abnormally open. Thereby, it is possible to distinguish and determine the opening abnormality on both the advance chamber side and the retardation chamber side and the opening abnormality on only one side.

  By the way, if a “closed abnormality” that does not move while the drain switching valve is closed occurs, the drain is reversed even in the control region where it is necessary to drain hydraulic oil from the hydraulic chamber where the closed abnormality has occurred (necessary to release the hydraulic pressure). Since it is hindered by the stop valve, it becomes difficult to change the VCT displacement angle with good response by following the change of the target displacement angle.

  Focusing on this characteristic, as in claim 5, when the target displacement angle changes, the convergence of the VCT displacement angle to the target displacement angle is determined, and the drain switching valve does not move while closed based on the convergence. It may be determined whether or not a closing abnormality has occurred. In this way, whether or not the drain switching valve is closed abnormally can be determined based on whether or not the convergence of the VCT displacement angle to the target displacement angle when the target displacement angle changes has deteriorated beyond the normal range. During the engine operation, the drain switching valve closing abnormality can be detected at an early stage.

  In this case, as in claim 6, the time during which the state where the deviation between the target displacement angle and the VCT displacement angle is equal to or greater than a predetermined value is measured as data representing convergence, and the drain switching valve is based on the duration. It may be determined whether or not there is an abnormal closing. Thereby, convergence can be determined easily.

  Alternatively, as in claim 7, after the deviation between the target displacement angle and the VCT displacement angle becomes equal to or greater than a first predetermined value, the deviation is equal to or less than a second predetermined value that is smaller than the first predetermined value. It is also possible to measure the elapsed time up to the time as data representing convergence and determine whether or not the drain switching valve is closed abnormally based on the elapsed time. Even in this way, the convergence can be easily determined.

  By the way, in the region where the engine speed is low, the hydraulic pressure supplied to the hydraulic control valve (oil pump discharge hydraulic pressure) decreases and the response characteristic of the VCT displacement angle decreases, so the VCT displacement angle converges to the target displacement angle. It is inevitable that the sex will decline.

  Considering this point, as in claim 8, the convergence of the VCT displacement angle to the target displacement angle is determined on the precondition that the hydraulic pressure supplied to the hydraulic control valve is a predetermined value or more. It is good to make it. In this way, it is possible to prevent misjudgment of convergence and, in turn, misjudgment of closing abnormality when the hydraulic pressure is low in the low rotation region, thereby improving the accuracy and reliability of abnormality diagnosis.

  In this case, a hydraulic pressure sensor that detects the hydraulic pressure supplied to the hydraulic control valve may be provided, but the hydraulic pressure supplied to the hydraulic control valve (the oil pump's pressure) depends on the engine speed and oil temperature (viscosity of hydraulic oil). In consideration of the change in the discharge hydraulic pressure), as in claim 9, whether or not the hydraulic pressure supplied to the hydraulic control valve is equal to or higher than a predetermined value is information on the engine speed and / or oil temperature (for example, cooling) It may be determined based on (water temperature). In this way, since it is possible to estimate the hydraulic pressure supplied to the hydraulic control valve using information generally used for engine control, it is not necessary to provide a hydraulic sensor for detecting the hydraulic pressure, and there is a demand for cost reduction. Can be met.

  In the present invention, the hydraulic pressure switching valve for switching the hydraulic pressure for driving the drain switching valve may be provided separately from the hydraulic control valve. However, as in claim 10, the hydraulic pressure switching valve is integrated with the hydraulic control valve. It is better to have a structured. Thereby, the request | requirement of reduction of a number of parts, cost reduction, and compactness can be satisfy | filled.

  The present invention can be applied to a vane type variable valve timing adjusting mechanism having a configuration different from that of the first and fifth aspects.

  For example, as in claims 11 and 15, the vane-type variable valve timing adjustment mechanism (hereinafter referred to as “VCT”) is provided in the hydraulic supply oil passage of the advance chamber in at least one vane storage chamber, A first check valve that is hydraulically driven and provided in a first drain oil passage that bypasses the first check valve and a first check valve that prevents backflow of hydraulic oil from the advance chamber A switching valve, a second check valve provided in a hydraulic pressure oil passage of the retard chamber of at least one vane storage chamber to prevent backflow of hydraulic oil from the retard chamber, and the second reverse valve A second drain switching valve that is driven by hydraulic pressure, provided in a second drain oil passage that bypasses the stop valve; a first hydraulic control valve that controls the hydraulic pressure supplied to the VCT; Second hydraulic control for controlling the hydraulic pressure for driving the second drain switching valve It may be configured to provided a valve. In this configuration, during the holding operation for maintaining the VCT displacement angle at the target displacement angle, both the advance chamber side and the retard chamber side drain switching valves are closed to both the advance chamber side and the retard chamber side. The first hydraulic pressure control valve controls the second hydraulic pressure control valve so as to effectively function the check valve to prevent the backflow of hydraulic oil from the advance angle chamber and the retard angle chamber, and also controls the hydraulic pressure supplied to the VCT. The control current of the hydraulic control valve is controlled to a predetermined holding current. Further, during the advance / retard operation for displacing the VCT displacement angle in the advance direction or the retard direction, either the advance chamber side or the retard chamber side drain switching valve according to the displacement direction And the second hydraulic control valve is controlled so that one of the check valves does not function, and the hydraulic pressure supplied to the VCT is varied by controlling the control current of the first hydraulic control valve. Thus, the VCT displacement angle is displaced toward the target displacement angle.

  The invention according to claims 1 to 10 can be applied to the VCT having such a configuration (claims 11 to 20).

  Further, as in claims 21 and 25, a first reverse for preventing the backflow of hydraulic oil from the advance chamber provided in the hydraulic supply oil passage of the advance chamber in at least one vane storage chamber of the VCT. A first drain switching valve that is driven by hydraulic pressure, provided in a first drain oil passage that bypasses the first check valve, and a hydraulic pressure in a retard chamber of at least one vane storage chamber; A second check valve provided in a supply oil passage for preventing a backflow of hydraulic oil from the retard chamber, and a second drain oil passage bypassing the second check valve; A second drain switching valve driven by hydraulic pressure, and the first and second drain switching valves and one hydraulic control valve for controlling the hydraulic pressure supplied to the VCT may be provided. In this configuration, during the holding operation for holding the VCT displacement angle at the target displacement angle, the control current of the hydraulic control valve is controlled to a predetermined holding current, so that both the advance chamber side and the retard chamber side drains are controlled. The VCT is controlled so that the check valve on both the advance chamber side and the retard chamber side functions effectively by preventing the backflow of hydraulic oil from the advance chamber and the retard chamber, by closing the switching valve. The hydraulic pressure supplied to the is controlled. Further, during the advance / retard operation for displacing the VCT displacement angle in the advance direction or the retard direction, the control current of the hydraulic control valve is controlled, and the advance chamber side is controlled according to the displacement direction. The drain switch valve on the retard chamber side is opened so that either check valve does not function, and the hydraulic pressure supplied to the VCT is varied to change the VCT displacement angle to the target displacement angle. Displace toward.

  The invention according to claims 1 to 9 can be applied to the VCT having such a configuration (claims 21 to 29).

  Hereinafter, four Examples 1 to 4 embodying the best mode for carrying out the present invention will be described.

  First, the configuration of the vane variable valve timing adjusting mechanism 11 will be described with reference to FIG. The housing 12 of the variable valve timing adjustment mechanism 11 is fastened and fixed with bolts 13 to a sprocket that is rotatably supported on the outer periphery of an intake-side or exhaust-side camshaft (not shown). Thereby, the rotation of the crankshaft of the engine is transmitted to the sprocket and the housing 12 via the timing chain, and the sprocket and the housing 12 rotate in synchronization with the crankshaft. A vane rotor 14 is accommodated in the housing 12 so as to be relatively rotatable, and the vane rotor 14 is fastened and fixed to one end portion of the camshaft by a bolt 15.

  Inside the housing 12, a plurality of vane storage chambers 16 for storing a plurality of vanes 17 on the outer periphery of the vane rotor 14 so as to be relatively rotatable in the advance angle direction and the retard angle direction are formed. The vane 17 is divided into an advance chamber 18 and a retard chamber 19.

  In a state where the hydraulic pressure of a predetermined pressure or higher is supplied to the advance chamber 18 and the retard chamber 19, the vane 17 is held by the hydraulic pressure of the advance chamber 18 and the retard chamber 19, and the housing 12 is rotated by the rotation of the crankshaft. Is transmitted to the vane rotor 14 via hydraulic pressure, and the camshaft is rotationally driven integrally with the vane rotor 14. During engine operation, the hydraulic pressure in the advance chamber 18 and the retard chamber 19 is controlled by the hydraulic control valve 21 to rotate the vane rotor 14 relative to the housing 12, so that the cam shaft displacement angle (cam The valve timing of the intake valve (or exhaust valve) is varied by controlling the axial phase.

  Further, stopper portions 22 and 23 for restricting the relative rotation range of the vane rotor 14 with respect to the housing 12 are formed on both side portions of any one vane 17, and the cam shaft displacement angle (cam) is defined by the stopper portions 22 and 23. The most retarded angle position and the most advanced angle position (axis phase) are regulated. In addition, any one vane 17 is provided with a lock pin 24 for locking the cam shaft displacement angle at a predetermined lock position when the engine is stopped, and the lock pin 24 is provided on the housing 12. By fitting into a hole (not shown), the displacement angle of the camshaft is locked at a predetermined locking position. This lock position is set to a position suitable for starting (for example, a substantially intermediate position in the adjustable range of the cam shaft displacement angle).

  Oil (operating oil) in the oil pan 26 is supplied to the hydraulic control circuit of the variable valve timing adjustment mechanism 11 by the oil pump 27 via the hydraulic control valve 21. The hydraulic control circuit is discharged from a hydraulic supply oil passage 28 that supplies oil discharged from the advance pressure port of the hydraulic control valve 21 to the plurality of advance chambers 18 and a retard pressure port of the hydraulic control valve 21. A hydraulic supply oil passage 29 for supplying oil to the plurality of retarding chambers 19 is provided.

  The hydraulic supply oil passage 28 of the advance chamber 18 and the hydraulic supply oil passage 29 of the retard chamber 19 are provided with check valves 30 and 31 for preventing backflow of hydraulic oil from the chambers 18 and 19, respectively. ing. In this embodiment, check valves 30 and 31 are provided only for the hydraulic supply oil passages 28 and 29 of the advance chamber 18 and the retard chamber 19 of one vane storage chamber 16. Of course, the check valves 30 and 31 may be provided in the hydraulic supply oil passages 28 and 29 in the advance chamber 18 and the retard chamber 19 of the two or more vane storage chambers 16, respectively.

  Drain oil passages 32 and 33 that bypass the check valves 30 and 31 are provided in parallel in the hydraulic supply oil passages 28 and 29 of the chambers 18 and 19, respectively. The drain oil passages 32 and 33 are respectively provided with drains. Switching valves 34 and 35 are provided. Each drain switching valve 34, 35 is constituted by a spool valve that is driven in the valve closing direction by the hydraulic pressure (pilot pressure) supplied from the hydraulic control valve 21, and is opened by the springs 41, 42 when no hydraulic pressure is applied. Held in position. When the drain switching valves 34 and 35 are opened, the drain oil passages 32 and 33 are opened, and the check valves 30 and 31 do not function. When the drain switching valves 34 and 35 are closed, the drain oil passages 32 and 33 are closed, and the functions of the check valves 30 and 31 are effectively activated, so that backflow of oil from the hydraulic chambers 18 and 19 is prevented. Thus, the hydraulic pressure in the hydraulic chambers 18 and 19 is maintained.

  Since the drain switching valves 34 and 35 do not require electrical wiring, the drain switching valves 34 and 35 are compactly assembled together with the check valves 30 and 31 to the vane rotor 14 inside the variable valve timing adjustment mechanism 11. As a result, the drain switching valves 34 and 35 are arranged near the hydraulic chambers 18 and 19, and the drain oil passages 32 and 33 are opened with good response near the hydraulic chambers 18 and 19 during advance / retard operation. It can be closed.

  On the other hand, the hydraulic control valve 21 is constituted by a spool valve driven by a linear solenoid 36, and an advance / retarding hydraulic control function 37 for controlling the hydraulic pressure supplied to the advance chamber 18 and the retard chamber 19, and each drain. A drain switching control function 38 for switching the hydraulic pressure for driving the switching valves 34 and 35 is integrated. A current value (control duty) energized to the linear solenoid 36 of the hydraulic control valve 21 is controlled by an engine control circuit (hereinafter referred to as “ECU”) 43.

  The ECU 43 calculates the actual valve timing (actual displacement angle) of the intake valve (or exhaust valve) based on the output signals of the crank angle sensor 44 and the cam angle sensor 45, and operates the engine such as an intake pressure sensor and a water temperature sensor. The target valve timing (target displacement angle) of the intake valve (or exhaust valve) is calculated based on the outputs of various sensors that detect the state. Then, the ECU 43 performs feedback control (or feedforward control) of the control current value of the hydraulic control valve 21 of the variable valve timing adjustment mechanism 11 so that the actual valve timing coincides with the target valve timing. As a result, the oil pressure in the advance chamber 18 and the retard chamber 19 is controlled to rotate the vane rotor 14 relative to the housing 12, thereby changing the cam shaft displacement angle and setting the actual valve timing to the target valve timing. Match.

  By the way, when the intake valve and the exhaust valve are driven to open and close during engine operation, the torque fluctuation received by the camshaft from the intake valve and the exhaust valve is transmitted to the vane rotor 14, thereby causing the retard direction and advance angle with respect to the vane rotor 14. Torque fluctuation in the direction acts. Thus, when the vane rotor 14 receives torque fluctuation in the retarding direction, the hydraulic oil in the advance chamber 18 receives pressure that is pushed out from the advance chamber 18, and when the vane rotor 14 receives torque fluctuation in the advance direction, the retard angle The hydraulic oil in the chamber 19 receives a pressure pushed out from the retard chamber 19. For this reason, in the low rotation region where the discharge hydraulic pressure of the oil pump 27 as the hydraulic pressure supply source is low, if there is no check valve 30, 31, the hydraulic pressure is supplied to the advance chamber 18 to advance the displacement angle of the camshaft. Even when trying to do so, as indicated by the dotted line in FIG. 3, the vane rotor 14 is pushed back in the retarded direction due to the torque fluctuation, and there is a problem that the response time until reaching the target displacement angle becomes long. .

  On the other hand, in the first embodiment, a check that prevents backflow of oil from the chambers 18 and 19 into the hydraulic supply oil passage 28 of the advance chamber 18 and the hydraulic supply oil passage 29 of the retard chamber 19 respectively. In addition to providing the valves 30 and 31, the hydraulic oil supply passages 28 and 29 of the chambers 18 and 19 are provided in parallel with drain oil passages 32 and 33 that bypass the check valves 30 and 31, respectively. 33 is provided with drain switching valves 34 and 35, respectively. As a result, as shown in FIG. 2, the hydraulic pressures in the chambers 18 and 19 are controlled as follows according to the retarding operation, holding operation, and advancement operation.

[Delay operation]
During the retard operation that retards the actual valve timing toward the target valve timing on the retard side, the hydraulic pressure supply to the drain switching valve 34 in the advance chamber 18 is stopped, so that the drain switching valve in the advance chamber 18 is stopped. 34 is opened so that the check valve 30 of the advance chamber 18 does not function, and the hydraulic pressure is applied from the hydraulic control valve 21 to the drain switching valve 35 of the retard chamber 19, so that the drain of the retard chamber 19 is drained. The switching valve 35 is closed to make the check valve 31 of the retard chamber 19 function. As a result, even when the hydraulic pressure is low, the hydraulic pressure is efficiently supplied to the retarded angle chamber 19 while preventing the backflow of oil from the retarded angle chamber 19 by the check valve 31 against the torque fluctuation in the advanced angle direction of the vane rotor 14. To improve retardation response.

[Holding operation]
During the holding operation for maintaining the actual valve timing at the target valve timing, both the drain switching valves are provided by applying hydraulic pressure from the hydraulic control valve 21 to the drain switching valves 34 and 35 of both the advance chamber 18 and the retard chamber 19. Both the valves 34 and 35 are closed so that the check valves 30 and 31 of both the advance chamber 18 and the retard chamber 19 are made to function. In this state, even if torque fluctuations acting on the vane rotor 14 in the retarding direction and the advancement direction act on the vane rotor 14 due to torque fluctuations received by the camshaft from the intake valve or the exhaust valve, The reverse flow of the oil is prevented by the check valve 31, and the hydraulic pressure for holding the vane 17 from both sides is prevented from being lowered to improve the holding stability.

[Advance operation]
During the advance operation for advancing the actual valve timing toward the target valve timing on the advance side, the hydraulic pressure is applied from the hydraulic control valve 21 to the drain switching valve 34 of the advance chamber 18, thereby draining the advance chamber 18. The switching valve 34 is closed to make the check valve 30 of the advance chamber 18 function, and the hydraulic pressure supply to the drain switching valve 35 of the retard chamber 19 is stopped, so that the drain of the retard chamber 19 is stopped. The switching valve 35 is opened so that the check valve 31 of the retard chamber 19 does not function. Thus, even when the hydraulic pressure is low, the hydraulic pressure is efficiently supplied to the advance chamber 18 while preventing the backflow of oil from the advance chamber 18 by the check valve 30 against the torque fluctuation in the retard angle direction of the vane rotor 14. To improve the lead angle response.

  Next, response characteristics (hereinafter referred to as “VCT response characteristics”) of the variable valve timing adjustment mechanism 11 will be described with reference to FIG. FIG. 4 is obtained by measuring the relationship between the control current value of the hydraulic control valve 21 (hereinafter referred to as “OCV current value”) and the response speed of the variable valve timing adjustment mechanism 11 (hereinafter referred to as “VCT response speed”). An example of a VCT response characteristic is shown.

  In the first embodiment, since the check valves 30, 31 and the drain switching valves 34, 35 are provided in both the advance chamber 18 and the retard chamber 19, the VCT response speed is linear with respect to the change in the OCV current value. The VCT response speed changes suddenly at two locations by switching the opening / closing of the drain switching valves 34 and 35 without changing to the above. In the VCT response characteristics of FIG. 4, the sudden change point of the retarded VCT response speed is the point at which the drain switching valve 34 of the advance chamber 18 is switched from the closed valve to the open valve, and the sudden change in the advanced VCT response speed. The point is that the drain switching valve 35 of the retarding chamber 19 is switched from closed to open. The holding operation is performed in a region where the gradient of the VCT response speed change between the retard side VCT response speed sudden change point and the advance side VCT response speed sudden change point is small.

  By the way, when the years of use become longer, foreign matter is caught in the drain switching valves 34 and 35 and the check valves 30 and 31, or those valve bodies are fixed, so that the drain switching valves 34 and 35 and the check valves 30, There is a possibility that an “open abnormality” that does not move while 31 is open may occur. Such an open abnormality causes deterioration of the engine performance, so it is necessary to detect it as early as possible and inform the driver to promote repair.

Therefore, in the first embodiment, the open abnormality is detected by the following method.
During the holding operation, if both the drain switching valves 34 and 35 on the advance chamber 18 side and the retard chamber 19 side operate normally, both the drain switching valves 34 and 35 are closed. , 31 can operate the check flow prevention function of both check valves 30, 31 effectively, but one of the drain switching valves 34, 35 (or check valves 30, 31) is open. If an open abnormality occurs that does not move, the drain switching valves 34 and 35 (or the check valves 30 and 31) remain open even during the holding operation. For this reason, if any one of the drain switching valves 34, 35 (or the check valves 30, 31) is abnormally open during the holding operation, the hydraulic chamber 18, Since the hydraulic pressure of 19 leaks through the drain switching valves 34 and 35 (or the check valves 30 and 31) and decreases, the hydraulic pressure balance of both the hydraulic chambers 18 and 19 is lost, and the VCT displacement angle can be held at a fixed position. A phenomenon occurs in which the amount of change in the VCT displacement angle increases.

Focusing on this characteristic, in the first embodiment, the drain switching valves 34 and 35 and / or the check valve are determined depending on whether or not the amount of change in the VCT displacement angle within a predetermined period exceeds the normal range during the holding operation. Whether or not 30 and 31 are abnormally opened is determined.
In this case, various methods can be considered as a method of detecting the amount of change in the VCT displacement angle within a predetermined period during the holding operation. For example, the following method can be considered.

[Detection method of change amount of VCT displacement angle during holding operation (1)]
The difference between the VCT displacement angle immediately after the start of the holding operation and the VCT displacement angle when a predetermined period has elapsed is calculated, and based on this difference, whether or not the drain switching valves 34 and 35 and / or the check valves 30 and 31 are abnormally opened is determined. judge. In this case, when the VCT displacement angle after the predetermined period has deviated from the VCT displacement angle immediately after the start of the holding operation is abnormally deviated in the retarded direction and abnormally deviated in the advance direction. And the drain switching valves 34 and 35 (or the check valves 30 and 31) are distinguished from each other on the side of the advance chamber 18 side or the retard chamber 19 side. It is possible to determine, and it is possible to specify the location where the open abnormality occurs.

  For example, as indicated by a one-dot chain line in FIG. 5, if the VCT displacement angle during the holding operation deviates significantly in the retard direction, the advance chamber 18 side that applies hydraulic pressure to the vane 17 in the advance direction will be described. It may be determined that the drain switching valve 34 (or check valve 30) is abnormally open and the hydraulic pressure in the advance chamber 18 leaks through the drain switching valve 34 (or check valve 30) and decreases. it can. Further, if the VCT displacement angle during the holding operation is abnormally greatly shifted in the advance direction, the drain switching valve 35 (or the check valve 31) on the retard chamber 19 side that applies the hydraulic pressure to the vane 17 in the retard direction. ) Is an abnormal opening, and it can be determined that the hydraulic pressure in the retard chamber 19 leaks and decreases through the drain switching valve 35 (or the check valve 31).

[Detection method of change amount of VCT displacement angle during holding operation (2)]
If both the drain switching valves 34 and 35 (or the check valves 30 and 31) on both the advance chamber 18 side and the retard chamber 19 side are abnormally open, the holding operation is being performed (particularly from the oil pump 27). Since the return of the VCT displacement angle due to the camshaft friction torque occurs in synchronization with the rotation of the camshaft during the holding operation in the low rotation region where the supply hydraulic pressure is low), as shown in FIG. A phenomenon occurs in which the displacement angle vibrates relatively large alternately in the advance direction and the retard direction around the target displacement angle in synchronization with the rotation of the camshaft.

  Considering this characteristic, the maximum and minimum values of the VCT displacement angle from immediately after the start of the holding operation until the elapse of a predetermined period are detected and the difference between them is calculated, and the drain switching valves 34 and 35 are calculated based on this difference. And / or the presence or absence of abnormal opening of the check valves 30 and 31 is determined. In this case, since the maximum width of the vibration range of the VCT displacement angle is known from the difference between the maximum value and the minimum value of the VCT displacement angle, the difference between the maximum value and the minimum value of the VCT displacement angle (maximum width of the vibration range) is normal. If it exceeds the range, it can be determined that the drain switching valves 34 and 35 and / or the check valves 30 and 31 on both the advance chamber 18 side and the retard chamber 19 side are abnormally opened.

[Method of detecting change amount of VCT displacement angle during holding operation (3)]
The maximum value and the minimum value of the VCT displacement angle from the start of the holding operation until the predetermined period elapses are detected, the deviation between the target displacement angle and the maximum value during the holding operation, the target displacement angle and the minimum value, And determining whether or not the drain switching valves 34 and 35 and / or the check valves 30 and 31 are open abnormally based on these two deviations. In this way, the change amount (deviation) in the advance direction of the VCT displacement angle is compared with the change amount (deviation) in the retard direction based on the target displacement angle, and the change amount (deviation) in both directions is obtained. If the degree is the same, it can be determined that the drain switching valves 34 and 35 (or the check valves 30 and 31) on both the advance chamber 18 side and the retard chamber 19 side are abnormally opened, When only the amount of change (deviation) is abnormally large, it can be determined that only one of the drain switching valves 34 and 35 (or the check valves 30 and 31) is abnormally opened. Thereby, it is possible to distinguish and determine the opening abnormality on both the advance chamber 18 side and the retardation chamber 19 side and the opening abnormality on only one side.

  In the following description, for convenience of explanation, the combination of “check valve” and “drain switching valve” is referred to as “check valve mechanism”, and “opening abnormality of check valve and / or drain switching valve” is “ It is written as “Check valve mechanism open abnormality”.

  In the first embodiment, the ECU 43 executes the abnormality diagnosis routines of FIGS. 7 to 9 to combine the above three VCT displacement angle change detection methods (1) to (3) for a predetermined period during the holding operation. The amount of change in the VCT displacement angle is determined to determine whether the drain switching valves 34 and 35 and / or the check valves 30 and 31 are open abnormally as follows.

  The abnormality diagnosis routines of FIGS. 7 to 9 are executed at every engine rotation speed calculation timing (for example, every 180 ° C. for a 4-cylinder engine) during engine operation, and serve as abnormality diagnosis means in the claims. Play a role. When this routine is started, first, at step 101, a target displacement angle vvttgt (target valve timing) corresponding to the current engine operating conditions (engine speed, intake pressure, etc.) is calculated from a map or the like. Thereafter, the process proceeds to step 102, where the OCV current value (control duty duty vvt) is feedback-controlled (F / B control) so that the deviation between the current VCT displacement angle vvt and the target displacement angle vvttgt becomes small.

  Thereafter, the process proceeds to step 103, where it is determined whether or not the abnormality diagnosis execution flag xvvtchk is cleared to “0” which means that the abnormality diagnosis is not being executed, and the abnormality diagnosis execution flag xvvtchk is set to “1”. If so, it is determined that an abnormality diagnosis is being performed, and the process proceeds to the determination process of step 105.

  On the other hand, if it is determined in step 103 that the abnormality diagnosis in progress flag xvvtchk is cleared to “0”, it is determined that the abnormality diagnosis is not in progress, and the process proceeds to step 104, where the current target is set. It is determined whether or not the absolute value | vvttgt−vvt | of the deviation between the displacement angle vvttgt and the VCT displacement angle vvt is equal to or less than the holding operation determination threshold value K1 (for example, 1 deg or less). As a result, if it is determined that the absolute value | vvttgt−vvt | of the deviation is larger than the holding operation determination threshold value K1, it is determined that the holding operation execution condition is not satisfied, and the process proceeds to step 106, where an abnormality is detected. The diagnostic execution flag xvvtchk is cleared to “0”, and the process proceeds to step 117 in FIG.

On the other hand, if it is determined in step 104 that the absolute value | vvttgt−vvt | of the deviation between the current target displacement angle vvttgt and the VCT displacement angle vvt is equal to or smaller than the holding operation determination threshold value K1, the process proceeds to step 105, where an abnormality occurs. Whether the diagnosis execution condition is satisfied is determined by, for example, whether all of the following conditions (1) to (3) are satisfied.
(1) The engine speed is higher than the specified speed
(2) The engine oil temperature (or cooling water temperature) is higher than the specified temperature.
(3) The discharge hydraulic pressure of the oil pump 27 is not less than a predetermined value.

  If any one of the three conditions (1) to (3) is not satisfied, the abnormality diagnosis execution condition is not established, and the process proceeds to step 106, where the abnormality diagnosis execution flag xvvtchk is set to “0”. Clear and go to step 117 of FIG.

  If it is determined in step 105 that all of the above three conditions (1) to (3) are satisfied and the abnormality diagnosis execution condition is satisfied, the process proceeds to step 107 and the previously learned holding duty (holding) Current) is read and the holding operation is started, and at the same time, the abnormality diagnosis process is started.

  In the holding duty learning, the learning value of the holding duty may be updated each time a predetermined holding duty learning condition is satisfied every time the holding operation is executed, or the learning frequency of the holding duty may be updated. You may make it less. Further, the holding duty may be learned for each region of the target displacement angle vvttgt (or for each engine operation region). Of course, one holding duty common to all the target displacement angles vvttgt (or all the engine operation regions). You may be made to learn. The learned holding duty is updated and stored in a rewritable nonvolatile memory such as a backup RAM of the ECU 43.

  In the next step 108, it is determined whether or not the abnormality diagnosis execution flag xvvtchk is “0”. If the abnormality diagnosis execution flag xvvtchk is set to “1”, the abnormality diagnosis is being executed. Therefore, the initialization process at the start of the abnormality diagnosis in steps 109 to 112 is skipped, and the process proceeds to the determination process in step 113 of FIG.

  On the other hand, if it is determined in step 105 that the abnormality diagnosis execution condition is satisfied and it is determined in step 108 that the abnormality diagnosis execution flag xvvtchk is “0”, the abnormality diagnosis is started ( At the start of the holding operation, initialization processing at the start of abnormality diagnosis in steps 109 to 112 is executed.

  In the initialization process at the time of starting abnormality diagnosis, first, at step 109, the abnormality diagnosis execution time counter cvvtret is initialized to zero. This abnormality diagnosis execution time counter cvvtret is a time counter that counts the elapsed time after the abnormality diagnosis is started (after the holding operation is started) by time synchronization processing different from this routine. In the next step 110, the current VCT displacement angle vvt is stored as the VCT displacement angle vvtret0 at the start of abnormality diagnosis (at the start of the holding operation). Thereafter, the process proceeds to step 111, where the current target displacement angle vvttgt is stored as the initial value of the VCT displacement angle minimum value vvtmin and the initial value of the VCT displacement angle maximum value vvtmax. xvvtchk is set to “1” which means that abnormality diagnosis is being executed, and the process proceeds to the determination process in step 113 of FIG.

  Then, in step 113 of FIG. 8, the stored value of VCT displacement angle minimum value vvtmin is compared with the current VCT displacement angle vvt, and the current VCT displacement angle vvt is more than the stored value of VCT displacement angle minimum value vvtmin. If the current VCT displacement angle vvt is not less than the stored value of the VCT displacement angle minimum value vvtmin, the process proceeds to step 114 where the current VCT displacement angle vvt is updated and stored as the VCT displacement angle minimum value vvtmin. The stored value of the minimum displacement angle value vvtmin is not updated. By repeating the processes of steps 113 and 114 during the abnormality diagnosis period, the VCT displacement angle minimum value vvtmin during the abnormality diagnosis period is updated and stored.

  Thereafter, the routine proceeds to step 115, where the stored value of the VCT displacement angle maximum value vvtmax is compared with the current VCT displacement angle vvt, and the current VCT displacement angle vvt is greater than the stored value of the VCT displacement angle maximum value vvtmax. If it is larger, the process proceeds to step 116, where the current VCT displacement angle vvt is updated and stored as the VCT displacement angle maximum value vvtmax. If the current VCT displacement angle vvt is less than or equal to the stored value of the VCT displacement angle maximum value vvtmax, the VCT displacement The stored value of the maximum angle value vvtmax is not updated. By repeating the processes of steps 115 and 116 during the abnormality diagnosis period, the VCT displacement angle maximum value vvtmax during the abnormality diagnosis period is updated and stored.

  Then, in the next step 117, it is determined whether or not the abnormality diagnosis execution flag xvvtchk is set to “1”. If it is not set to “1”, it is determined that the abnormality diagnosis is not being executed, This routine is finished as it is.

  On the other hand, if it is determined in step 117 that the abnormality diagnosis execution flag xvvtchk is set to “1”, it is determined that abnormality diagnosis is being executed, the process proceeds to step 118, and is measured by the abnormality diagnosis execution time counter cvvtret. It is determined whether or not the abnormality diagnosis execution time (elapsed time from the start of abnormality diagnosis) has reached a predetermined time K2 or more (for example, 3000 ms or more). If the predetermined time K2 has not been reached, this routine is terminated.

Thereafter, when the measurement time of the abnormality diagnosis execution time counter cvvtret reaches the predetermined time K2, it is determined “Yes” in step 119, and the process proceeds to step 119, where the VCT displacement angle vvtret0 at the time of abnormality diagnosis start and the current time (abnormal diagnosis) The deviation from the VCT displacement angle vvt at the time of completion is calculated, and this deviation is stored as a first abnormality diagnosis deviation dvvtdg1.
dvvtdg1 = vvtret0-vvt

  This first abnormality diagnostic deviation dvvtdg1 is an abnormality that indicates how much the VCT displacement angle vvt at the end of the abnormality diagnosis changes in the retarded / advanced direction with respect to the VCT displacement angle vvtret0 at the beginning of the abnormality diagnosis. It is a diagnostic parameter. If it is a positive value, it indicates that it has changed in the retard direction, and if it is a negative value, it indicates that it has changed in the advance direction.

Thereafter, the process proceeds to step 120, where a deviation between the maximum VCT displacement angle value vvtmax and the minimum VCT displacement angle value vvtmin during abnormality diagnosis is calculated, and this deviation is stored as a second abnormality diagnosis deviation dvvtdg2.
dvvtdg2 = vvtmax−vvtmin
The second abnormality diagnosis deviation dvvtdg2 is an abnormality diagnosis parameter representing the maximum width of the vibration range of the VCT displacement angle vvt during abnormality diagnosis.

In the next step 121, a deviation (vvtmax-vvttgt) between the maximum VCT displacement angle value vvtmax during abnormality diagnosis and the current (abnormal diagnosis) target displacement angle vvttgt is calculated, and the minimum VCT displacement angle value vvtmin is calculated. A deviation (vvtmin−vvttgt) from the current (during abnormality diagnosis) target displacement angle vvttgt is calculated, and an absolute value of a value obtained by adding these two deviations is stored as a third abnormality diagnosis deviation dvvtdg3.
dvvtdg3
= | (Vvtmax−vvttgt) + (vvtmin−vvttgt) |

  This third abnormality diagnostic deviation dvvtdg3 is an abnormality diagnosis that evaluates how much the vibration range of the VCT displacement angle vvt under abnormality diagnosis deviates from the vibration range centered on the target displacement angle vvttgt in the advance angle or retard angle direction. It becomes a parameter. As shown in FIG. 3, when the center of the vibration range of the VCT displacement angle vvt during abnormality diagnosis is close to the target displacement angle vvttgt, one deviation (vvtmax−vvttgt) becomes a positive value and the other deviation (vvtmin−vvttgt) ) Is a negative value, and the absolute values of both deviations are close to each other, so that the third abnormality diagnosis deviation dvvtdg3 is close to 0. Therefore, as the third abnormality diagnostic deviation dvvtdg3 increases, it means that the vibration range of the VCT displacement angle vvt during the abnormality diagnosis is greatly shifted in the retarded or advanced direction. The third abnormality diagnostic deviation dvvtdg3 and the second abnormality diagnostic deviation dvvtdg2 indicate that the check valve mechanisms on both the advance chamber 18 side and the retard chamber 19 side are opened abnormally and only one check valve mechanism is opened. It is used to distinguish and distinguish between abnormalities.

  Thereafter, the process proceeds to step 122 in FIG. 9 to determine whether or not the third abnormality diagnostic deviation dvvtdg3 is smaller than a predetermined value K3 (for example, 1 deg), and if the third abnormality diagnostic deviation dvvtdg3 is equal to or larger than the predetermined value K3. For example, since the vibration range of the VCT displacement angle vvt during the abnormality diagnosis is greatly shifted in the retard angle or advance direction, the check valve mechanisms on both the advance chamber 18 side and the retard chamber 19 side become open abnormal. If it is determined that the state is not, the routine proceeds to step 124, where the both check valve mechanism opening abnormality flag xwofail is cleared to "0".

  On the other hand, if it is determined in step 122 that the third abnormality diagnostic deviation dvvtdg3 is smaller than the predetermined value K3, the process proceeds to step 123, where the second abnormality diagnostic deviation dvvtdg2 is a predetermined value K4 (for example, 7 deg). Or less. As a result, if it is determined that the second abnormality diagnosis deviation dvvtdg2 is equal to or greater than the predetermined value K4, the maximum width of the vibration range of the VCT displacement angle vvt during abnormality diagnosis exceeds the normal range, and therefore the advance chamber 18 It is determined that both of the check valve mechanisms on the side and the retarded angle chamber 19 side are in an open abnormality state, the process proceeds to step 125, and both the check valve mechanism open abnormality flag xwofail is set to "1". Thereafter, the routine proceeds to step 132, where the abnormality diagnosis processed flag xdiagend is set to “1” which means the abnormality diagnosis processing is ended, and this routine is ended. This abnormality diagnosis process completed flag xdiagend is cleared to “0” by the initialization process at the time of power-on to the ECU 43, and it is determined whether or not the above-described opening abnormality determination process is executed during the engine operation. Used for.

  On the other hand, in step 122, it is determined that the third abnormality diagnostic deviation dvvtdg3 is smaller than the predetermined value K3, and in step 123, it is determined that the second abnormality diagnostic deviation dvvtdg2 is smaller than the predetermined value K4. For example, it is determined that both check valve mechanisms are not in an open abnormality state, and the routine proceeds to step 124, where both check valve mechanism open abnormality flags xwofail are cleared to "0".

  In short, when the third abnormality diagnostic deviation dvvtdg3 is smaller than the predetermined value K3 and the second abnormality diagnostic deviation dvvtdg2 is equal to or larger than the predetermined value K4 (that is, the VCT displacement angle vvt vibrates around the target displacement angle vvttgt). Only when the maximum width of the vibration range exceeds the normal range), it is determined that both check valve mechanisms are both in an abnormal open state, and the process proceeds to step 125, where both check valve mechanism open abnormalities are detected. The flag xwopenfail is set to “1”. In other cases, the both check valve mechanism opening abnormality flag xwopenfail is cleared to “0”.

  Thereafter, the process proceeds to step 126, where it is determined whether or not the first abnormality diagnostic deviation dvvtdg1 is equal to or greater than a predetermined value K5 (for example, 5 deg or greater). If the first abnormality diagnostic deviation dvvtdg1 is equal to or greater than the predetermined value K5, Since the VCT displacement angle vvt at the end of the abnormality diagnosis changes abnormally in the advance direction with respect to the VCT displacement angle vvtret0 at the start of the abnormality diagnosis, the check valve mechanism on the advance chamber 18 side becomes abnormally open. In step 127, the advance angle chamber side check valve mechanism opening abnormality flag xadvfail is set to "1". On the other hand, if the first abnormality diagnostic deviation dvvtdg1 is less than the predetermined value K5, the routine proceeds to step 128, where the advance chamber side check valve mechanism opening abnormality flag xadvfail is cleared to “0”.

Thereafter, the process proceeds to step 129, in which it is determined whether or not the first abnormality diagnostic deviation dvvtdg1 is equal to or smaller than a predetermined value K6 (for example, −5 deg or smaller), and if the first abnormality diagnostic deviation dvvtdg1 is equal to or smaller than the predetermined value K5. Since the VCT displacement angle vvt at the end of the abnormality diagnosis has changed abnormally greatly from the VCT displacement angle vvtret0 at the start of the abnormality diagnosis in the retard direction, the check valve mechanism on the retard chamber 19 side becomes abnormally open. In step 130, the retard chamber side check valve mechanism opening abnormality flag xretfail is set to "1". On the other hand, when the first abnormality diagnosis deviation dvvtdg1 is larger than the predetermined value K6, the routine proceeds to step 131, where the retarded chamber side check valve mechanism opening abnormality flag xretfail is cleared to “0”.
Thereafter, the routine proceeds to step 132, where the abnormality diagnosis processing completed flag xdiagend is set to "1" which means the completion of the abnormality diagnosis processing, and this routine is ended.

  An example of the abnormality diagnosis of the first embodiment described above is shown in the time charts of FIGS. In the example of FIGS. 5 and 6, the F / B control is performed so that the target displacement angle vvttgt changes in the advance direction at time t1, and the VCT displacement angle vvt changes in the advance direction following the change. . As a result, the absolute value of the deviation between the target displacement angle vvttgt and the VCT displacement angle vvt becomes equal to or smaller than the predetermined value, and at the time t2 when the predetermined holding operation execution condition is satisfied, the holding operation is started and the abnormality diagnosis process is started at the same time. To do. During the execution of the holding operation (abnormality diagnosis), the control duty dutyvvt of the hydraulic control valve 21 is maintained at the previously learned holding duty, and the target displacement angle vvttgt is maintained constant.

  In the example of FIG. 5, the behavior of the VCT displacement angle vvt when an opening abnormality that does not move while the check valve mechanism on the advance angle chamber 18 side is open is indicated by a one-dot chain line. When the check valve mechanism on the advance angle chamber 18 side becomes abnormally open, the hydraulic pressure in the advance angle chamber 18 in which the open error has occurred leaks through the check valve mechanism and decreases. A phenomenon occurs in which the hydraulic pressure of the corner chamber 18 becomes higher and the VCT displacement angle vvt shifts in the retarded direction.

  For this reason, if an opening abnormality of the check valve mechanism on the advance angle chamber 18 side has occurred, an abnormality that evaluates the amount of change in the retard direction of the VCT displacement angle vvt during the abnormality diagnosis at the time t3 when the abnormality diagnosis ends. The first abnormality diagnosis deviation dvvtdg1 (= vvtret0-vvt), which is a diagnostic parameter, is equal to or greater than a predetermined value K5 (for example, 5 deg or greater), and it is determined that the check valve mechanism on the advance chamber 18 side is abnormally open. The advance chamber side check valve mechanism opening abnormality flag xadvfail is set to “1”. In this case, a third abnormality diagnosis deviation dvvtdg3, which is an abnormality diagnosis parameter for evaluating how much the vibration range of the VCT displacement angle vvt during abnormality diagnosis is shifted in the advance or retard direction, is a predetermined value K3 or more (for example, Therefore, it is determined that the check valve mechanisms on both the advance chamber 18 side and the retard chamber 19 side are not in an abnormal opening state.

  In the example of FIG. 6, the behavior of the VCT displacement angle vvt when both the check valve mechanisms on the advance chamber 18 side and the retard chamber 19 side are abnormally open is shown. If both check valve mechanisms are abnormally open, the return of the VCT displacement angle vvt due to the camshaft friction torque occurs during the holding operation in synchronization with the rotation of the camshaft. A phenomenon occurs in which the VCT displacement angle vvt vibrates relatively large alternately in the advance direction and the retard direction about the target displacement angle vvttgt in synchronization with the rotation of the camshaft.

  Therefore, when both check valve mechanisms are abnormally open, an abnormality diagnosis parameter for evaluating how much the vibration range of the VCT displacement angle vvt during abnormality diagnosis is shifted in the advance or retard direction. The third abnormality diagnosis deviation dvvtdg3 is smaller than a predetermined value K3 (for example, 1 deg), and is a second abnormality diagnosis parameter which is an abnormality diagnosis parameter representing the maximum width of the vibration range of the VCT displacement angle vvt during abnormality diagnosis. Since the deviation dvvtdg2 is equal to or greater than a predetermined value K4 (for example, 7 deg or greater), it is determined that both check valve mechanisms are in an open abnormality state, and both check valve mechanism open abnormality flag xwofenfail is “1”. Set to

  According to the first embodiment described above, the first abnormality diagnosis deviation dvvtdg1 (= vvtret0−) which is an abnormality diagnosis parameter for evaluating the amount of change in the VCT displacement angle vvt during a predetermined period (abnormality diagnosis period) after the holding operation is started. (vvt) exceeds the normal range, it is determined whether the check valve mechanism on the advance chamber 18 side or the retard chamber 19 side is abnormally open. An abnormal opening of the check valve mechanism on the corner chamber 18 side or the retard chamber 19 side can be detected at an early stage.

  Moreover, in the first embodiment, the deviation between the maximum VCT displacement angle value vvtmax and the minimum VCT displacement angle value vvtmin during abnormality diagnosis (maximum width of the vibration range of the VCT displacement angle vvt) is used as the second abnormality diagnosis deviation dvvtdg2. And calculating a deviation (vvtmax−vvttgt) between the maximum VCT displacement angle value vvtmax and the target displacement angle vvttgt during abnormality diagnosis, and a deviation (vvtmin−vvttgt) between the minimum VCT displacement angle value vvtmin and the target displacement angle vvttgt. ) And the absolute value of the sum of these two deviations is calculated as a third abnormality diagnosis deviation dvvtdg3, and the second abnormality diagnosis deviation dvvtdg2 and the third abnormality diagnosis deviation dvvtdg3 are calculated. An abnormality diagnosis parameter for evaluating a change amount / vibration range of the VCT displacement angle vvt; Since as adapted to use Te, can be determined by distinguishing between opening abnormality of the check valve mechanism opens anomalies and one side of both of the check valve mechanism only.

  The deviation (vvtmax−vvttgt) between the maximum VCT displacement angle value vvtmax and the target displacement angle vvttgt during abnormality diagnosis is compared with a predetermined value, or the minimum VCT displacement angle value vvtmin and target displacement angle vvttgt during abnormality diagnosis are compared. By comparing the deviation (vvtmin−vvttgt) with a predetermined value, it may be determined whether or not the change amount / vibration range of the VCT displacement angle vvt during abnormality diagnosis is within the normal range.

In the first embodiment, the abnormality diagnosis process is started simultaneously with the start of the holding operation. However, the abnormality diagnosis process may be started after a predetermined time has elapsed from the start of the holding operation.
Further, according to the present invention, a hydraulic pressure switching valve for switching the hydraulic pressure for driving the drain switching valves 34 and 35 may be provided separately from the hydraulic pressure control valve 21, but in the first embodiment, the hydraulic pressure switching valve is provided. Since the configuration is integrated with the hydraulic control valve 21, there is an advantage that the demands for reduction in the number of parts, cost reduction, and compactness can be satisfied.

  By the way, when a “close abnormality” occurs in which the drain switching valves 34 and 35 are closed, the oil is required to be drained from the hydraulic chambers 18 and 19 in which the close abnormality has occurred (necessary to release the hydraulic pressure). Since the drain is obstructed by the check valves 30 and 31, it becomes difficult to change the VCT displacement angle vvt with good response by following the change of the target displacement angle vvttgt.

  Focusing on this characteristic, in the second embodiment of the present invention shown in FIGS. 10 to 12, when the target displacement angle vvttgt changes, the convergence of the VCT displacement angle vvt to the target displacement angle vvttgt is determined and the convergence is achieved. On the basis of this, it is determined whether or not a closing abnormality has occurred in which the drain switching valves 34 and 35 are not moved while being closed.

  In the second embodiment, when the target displacement angle vvttgt changes, the time cvvtchkc in which the absolute value of the deviation between the target displacement angle vvttgt and the VCT displacement angle vvt continues to be a predetermined value K7 or more (for example, 4 deg or more) is converged. Whether or not the drain switching valves 34 and 35 are abnormally closed is determined based on whether or not the time cvvtchkc exceeds a closing abnormality determination threshold value K8 (for example, 3000 ms). At this time, if the state where the VCT displacement angle vvt is shifted in the retarded direction with respect to the target displacement angle vvttgt continues, the drain switching valve 35 on the retard chamber 19 side is closed abnormally (because the retard chamber 19 cannot be drained). If the VCT displacement angle vvt continues to deviate in the advance direction, the drain switch valve 35 on the retard chamber 19 side is closed abnormally (the drain of the advance chamber 18 can be drained). Therefore, it is determined that the abnormality is difficult to retard.

  The abnormality diagnosis process of the second embodiment described above is executed by the ECU 43 according to the abnormality diagnosis routines of FIGS. This routine is executed at every engine rotation speed calculation timing (for example, every 180 ° C. A for a four-cylinder engine) during engine operation, and serves as an abnormality diagnosis means in the claims. When this routine is started, first, in step 201, a target displacement angle vvttgt (target valve timing) corresponding to the current engine operating conditions (engine speed, intake pressure, etc.) is calculated using a map or the like. Thereafter, the routine proceeds to step 202, where the OCV current value (control duty duty vvt) is feedback-controlled (F / B control) so that the deviation between the current VCT displacement angle vvt and the target displacement angle vvttgt becomes small.

  Thereafter, the process proceeds to step 203 to determine whether or not the holding operation is being performed. If the holding operation is being performed, the abnormality diagnosis execution condition is not satisfied, the process proceeds to step 212 and the convergence time counter cvvtchkc is set to “0”. At the same time, the advance angle deviation detection flag xadvjdg and the retard angle deviation detection flag xretjdg are both cleared to “0”, and this routine ends.

  On the other hand, if it is determined in step 203 that the holding operation is not being performed, the process proceeds to step 204 where the absolute value | vvttgt-vvt | of the deviation between the current target displacement angle vvttgt and the VCT displacement angle vvt is a predetermined value. If it is determined whether or not the absolute value | vvttgt-vvt | of the deviation is equal to or smaller than a predetermined value K7, the convergence of the VCT displacement angle vvt to the target displacement angle vvttgt is in the normal range. In step 212, the convergence time counter cvvtchkc is initialized, the advance deviation detection flag xadvjdg and the retard deviation detection flag xretjdg are both cleared, and this routine is terminated.

If it is determined in step 204 that the absolute value | vvttgt−vvt | of the deviation is larger than the predetermined value K7, the process proceeds to step 205 to determine whether or not the abnormality diagnosis execution condition is satisfied, for example: Judgment is made based on whether all the conditions (1) to (3) are satisfied.
(1) The engine speed is higher than the specified speed
(2) The engine oil temperature (or cooling water temperature) is higher than the specified temperature.
(3) The discharge hydraulic pressure of the oil pump 27 is not less than a predetermined value.

  If any one of the three conditions (1) to (3) is not satisfied, the abnormality diagnosis execution condition is not satisfied, and the process proceeds to step 212, the convergence time counter cvvtchkc is initialized, and the process proceeds. Both the angular deviation detection flag xadvjdg and the retardation deviation detection flag xretjdg are cleared, and this routine ends.

  On the other hand, if it is determined in step 205 that all three conditions (1) to (3) are satisfied and the abnormality diagnosis execution condition is satisfied, the process proceeds to step 206, where the current target displacement angle vvttgt and It is determined whether or not the deviation (vvttgt−vvt) from the VCT displacement angle vvt is a positive value. If the deviation (vvttgt−vvt) is a positive value, the current VCT displacement angle vvt is set to the target displacement angle vvttgt. On the other hand, it is determined that there is a shift in the retard angle direction, and the process proceeds to step 207 where it is determined whether or not the retard shift detection flag xretjdg that stores the shift direction on the retard side of the previous VCT displacement angle vvt is “0”. That is, it is determined whether or not the deviation direction of the previous VCT displacement angle vvt is the advance direction. As a result, if it is determined that the retard shift detection flag xretjdg is “0”, it is determined that the shift direction of the VCT displacement angle vvt is reversed from the previous advance direction to the retard direction, and the process proceeds to Step 209 to converge. The time counter cvvtchkc is initialized, and the retardation shift detection flag xretjdg is set to “1”, and the process proceeds to step 211.

  If “No” is determined in step 207, it is determined that the deviation direction of the VCT displacement angle vvt is the same retarding direction as in the previous time, and the process of step 209 is skipped and the process proceeds to step 211.

  On the other hand, if it is determined in step 206 that the deviation (vvttgt−vvt) between the current target displacement angle vvttgt and the VCT displacement angle vvt is 0 or less (minus value), the current VCT displacement angle vvt Is advanced in the advance direction with respect to the target displacement angle vvttgt, the process proceeds to step 208, and the advance angle detection flag xadvjdg that stores the advance direction shift direction of the previous VCT displacement angle vvt is “0”. (That is, whether or not the previous deviation direction of the VCT displacement angle vvt is the retard direction). As a result, if the advance angle shift detection flag xadvjdg is determined to be “0”, it is determined that the shift direction of the VCT displacement angle vvt is reversed from the previous retard direction to the advance direction, and the process proceeds to step 210 to converge. The time counter cvvtchkc is initialized and the advance deviation detection flag xadvjdg is set to “1”, and the process proceeds to step 211.

  If “No” is determined in step 208, it is determined that the deviation direction of the VCT displacement angle vvt is the same advance direction as the previous time, and the process of step 210 is skipped and the process proceeds to step 211.

  In this step 211, it is determined whether or not both of the advance deviation detection flag xadvjdg and the retardation deviation detection flag xretjdg are “1”, and both the advance deviation detection flag xadvjdg and the retardation deviation detection flag xretjdg are “1”. If “1”, it is determined that the shift in the advance angle direction and the shift in the retard angle direction are reversed in one calculation cycle, the process proceeds to step 212, the convergence time counter cvvtchkc is initialized, and the advance angle shift detection flag xadvjdg And the retardation shift detection flag xretjdg are both cleared and this routine is terminated.

  If “No” is determined in Step 211, it is determined that the deviation direction of the VCT displacement angle vvt is not reversed, and the process proceeds to Step 213 in FIG. 12, where the deviation between the target displacement angle vvttgt and the VCT displacement angle vvt is determined. Depending on whether or not the measurement time of the convergence time counter cvvtchkc that measures the time during which the absolute value of the value is equal to or greater than a predetermined value K7 (for example, 4 degrees or more) has exceeded the closed abnormality determination threshold K8 (for example, 3000 ms) It is determined whether or not the drain switching valves 34 and 35 are abnormally closed. This convergence time counter cvvtchkc is a time counter that counts the elapsed time after the start of abnormality diagnosis (after the start of convergence measurement) by time synchronization processing different from this routine. It is initialized with.

  If it is determined in step 213 that the measurement time of the convergence time counter cvvtchkc has not reached the closing abnormality determination threshold value K8, the present routine is terminated. Thereafter, when the measurement time of the convergence time counter cvvtchkc exceeds the closing abnormality determination threshold value K8, it is determined that one of the drain switching valves 34, 35 has a closing abnormality, the process proceeds to step 214, and the processing is delayed. It is determined whether or not the deviation direction of the VCT displacement angle vvt is the retard direction depending on whether or not the angular deviation detection flag xretjdg is “1”. As a result, if it is determined that the retard shift detection flag xretjdg is “1” (the shift direction of the VCT displacement angle vvt is the retard direction), the drain switching valve 35 on the retard chamber 19 side is closed abnormally (retard chamber 19). Therefore, the process proceeds to step 215 and sets the retarded chamber side drain switching valve closing abnormality flag xretchkf to “1”.

  On the other hand, if it is determined in step 214 that the retardation shift detection flag xretjdg is “0” (the shift direction of the VCT displacement angle vvt is the advance direction), the drain switching valve 34 on the advance chamber 18 side is closed abnormally ( In step 216, the advance chamber side drain switching valve closing abnormality flag xadvchkf is set to "1".

  Thereafter, the process proceeds to step 217, where it is determined whether or not both the retarded chamber side drain switching valve closing abnormality flag xretchkf and the advanced chamber side drain switching valve closing abnormality flag xadvchkf are “1”. If it is “Yes”, it is determined that the drain switching valves 34 and 35 on both the advance chamber 18 side and the retard chamber 19 side are abnormally closed, and step 218 is performed. Then, the two drain switching valve closing abnormality flag xchkvalvef is set to “1”, and this routine is finished.

  An example of the abnormality diagnosis of the second embodiment described above is shown in the time chart of FIG. In the example of FIG. 10, the F / B control is performed so that the target displacement angle vvttgt changes in the advance direction at time t1, and the VCT displacement angle vvt changes in the advance direction following the change. Due to the change in the advance direction of the target displacement angle vvttgt, the absolute value of the deviation between the target displacement angle vvttgt and the VCT displacement angle vvt becomes equal to or greater than a predetermined value K7 (for example, 4 deg), and the abnormality diagnosis execution condition is satisfied. At time t2, the time counting operation of the convergence time counter cvvtchkc is started, and the time during which the absolute value of the deviation between the target displacement angle vvttgt and the VCT displacement angle vvt is equal to or greater than the predetermined value K7 is measured.

  During the advance operation, the drain switching valve 35 on the retard chamber 19 side is opened to drain oil from the retard chamber 19 to reduce the hydraulic pressure in the retard chamber 19 and fill the advance chamber 18 with oil. Then, the hydraulic pressure of the advance chamber 18 is increased to control the VCT displacement angle vvt to converge with the target displacement angle vvttgt with good response. Therefore, if the drain switching valve 35 on the retard chamber 19 side is normally opened during the advance operation, the absolute value of the deviation between the target displacement angle vvttgt and the VCT displacement angle vvt is greater than or equal to the predetermined value K7. Since the continuing time (measurement time t2 to t3 of the convergence time counter cvvtchkc) becomes shorter than the closing abnormality determination threshold value K8, the retarded chamber side drain switching valve closing abnormality flag xretchkf is maintained at “0”.

  On the other hand, if an abnormal closing of the drain switching valve 35 on the retard chamber 19 side occurs, it becomes difficult to advance because the drain of the retard chamber 19 cannot be made, so the target displacement angle vvttgt and the VCT displacement angle vvt. The time during which the state where the absolute value of the deviation is equal to or greater than the predetermined value K7 continues (measurement time of the convergence time counter cvvtchkc) is long, and at the time t4 when the duration exceeds the closing abnormality determination threshold value K8. It is determined that a closing abnormality of the drain switching valve 35 on the corner chamber 19 side has occurred, and the retarding chamber side drain switching valve closing abnormality flag xretchkf is set to “1”.

  According to the second embodiment described above, when the target displacement angle vvttgt changes, the time cvvtchkc during which the absolute value of the deviation between the target displacement angle vvttgt and the VCT displacement angle vvt continues to be equal to or greater than the predetermined value K7 is converged. Therefore, it is determined whether or not the drain switching valves 34 and 35 are closed abnormally depending on whether or not the time cvvtchkc exceeds the closing abnormality determination threshold value K8. It is possible to detect an abnormal closing of the drain switching valves 34 and 35 at an early stage during operation.

  By the way, in the region where the engine speed is low, the hydraulic pressure supplied to the hydraulic control valve 21 (discharge hydraulic pressure of the oil pump 27) decreases and the response characteristic of the VCT displacement angle decreases, so that the VCT displacement angle reaches the target displacement angle. It is inevitable that the convergence of the will decrease.

  In consideration of this point, in the second embodiment, assuming that the hydraulic pressure supplied to the hydraulic control valve 21 is equal to or greater than a predetermined value (one of the abnormality diagnosis execution conditions), the target displacement of the VCT displacement angle is set. Since the convergence to the corner is judged, it is possible to prevent misjudgment of convergence when the hydraulic pressure is low in the low rotation range, and thus erroneous judgment of closing abnormality, and improve the accuracy and reliability of abnormality diagnosis. be able to.

  In this case, a hydraulic pressure sensor for detecting the hydraulic pressure supplied to the hydraulic control valve 21 may be provided, but the hydraulic pressure supplied to the hydraulic control valve 21 (oil) according to the engine rotation speed and the oil temperature (viscosity of hydraulic oil). In consideration of the change in the discharge hydraulic pressure of the pump 27, in the second embodiment, whether or not the hydraulic pressure supplied to the hydraulic control valve 21 is equal to or higher than a predetermined value is related to the engine speed and / or the oil temperature. The determination is made based on (for example, cooling water temperature). In this way, since it is possible to estimate the hydraulic pressure supplied to the hydraulic control valve 21 using information generally used for engine control, it is not necessary to provide a hydraulic pressure sensor for detecting the hydraulic pressure, and the cost can be reduced. Can meet the demand.

  In the second embodiment, the time during which the deviation (absolute value) between the target displacement angle and the VCT displacement angle when the target displacement angle changes is equal to or greater than the predetermined value K7 is measured as data representing convergence. However, after the deviation (absolute value) between the target displacement angle and the VCT displacement angle when the target displacement angle changes becomes equal to or greater than the first predetermined value, the deviation (absolute value) is greater than the first predetermined value. The elapsed time until it becomes smaller than the second predetermined value or less may be measured as data representing convergence, and based on the elapsed time, it may be determined whether or not the drain switching valves 34 and 35 are closed abnormally.

  In addition, the present invention may be implemented by combining the abnormality diagnosis process of the first embodiment and the abnormality diagnosis process of the second embodiment, or the configuration of the variable valve timing adjusting mechanism 11 may be changed as appropriate. Hereinafter, Examples 3 and 4 in which the configuration of the variable valve timing adjusting mechanism 11 is changed will be described.

  The variable valve timing adjusting mechanism 71 according to the third embodiment of the present invention shown in FIG. 13 is different from the variable valve timing adjusting mechanism 11 shown in FIG. In FIG. 13, the same components as those in FIG.

  First, the hydraulic control valve 21 in FIG. 1 drives the advance / retard hydraulic control function 37 and the drain switching control function 38 by a single linear solenoid 36, but in FIG. 13, the advance / retard hydraulic control. Solenoids 36 and 51 are provided in the first hydraulic control valve 37 for realizing the function and the second hydraulic control valve 38 for realizing the drain switching control function, respectively, and the solenoids 36 and 51 are controlled by separate ECUs 43 and 52, respectively. It is configured to do.

  As for the drain switching valves 34 and 35, in FIG. 1, when a hydraulic pressure is not applied, a so-called normally open type (normally open type) switching valve that is held in a valve open position by springs 41 and 42 is used. Yes. On the other hand, in FIG. 13, a so-called normally closed type (normally closed type) switching valve that is held in the closed position by the springs 41 and 42 when hydraulic pressure is not applied is used. Accordingly, the drain switching control function 38 is configured to supply hydraulic pressure when the drain switching valves 34 and 35 are closed in FIG. 1, but in FIG. 13, the drain switching valves 34 and 35 are closed. In this case, the hydraulic pressure supply is stopped.

  Further, in FIG. 1, check valves 30 and 31 and drains are provided in the hydraulic pressure supply passages 28 and 29 corresponding to the advance chamber 18 and the retard chamber 19 of one vane storage chamber 16 partitioned by one vane 17. In the configuration shown in FIG. 13, the switching valves 34 and 35 are provided. In FIG. 13, the hydraulic supply passage 28 for the advance chamber 18 of one vane storage chamber 16 and the hydraulic supply passage 29 for the retard chamber 19 of another vane storage chamber 16 are provided. Check valves 30 and 31 and drain switching valves 34 and 35 are provided.

  In this configuration, during the holding operation for maintaining the VCT displacement angle at the target displacement angle, the drain switching valves 34 and 35 on both the advance chamber 18 side and the retard chamber 19 side are closed to retard the advance chamber 18 side. The second hydraulic control valve 38 is controlled so that both check valves 30 and 31 on the corner chamber 19 side function effectively to prevent backflow of hydraulic oil from the advance chamber 18 and the retard chamber 19. Then, the control current of the first hydraulic control valve 37 that controls the hydraulic pressure supplied to the variable valve timing adjusting mechanism 71 is controlled to a predetermined holding current.

  On the other hand, during the advance / retard operation for displacing the VCT displacement angle in the advance direction or the retard direction, either the advance chamber 18 side or the retard chamber 19 side is switched according to the displacement direction. The second hydraulic control valve 38 is controlled so that either the check valve 30 or 31 does not function by opening the valve 34 or 35, and the control current of the first hydraulic control valve 37 is controlled to be variable. By varying the hydraulic pressure supplied to the valve timing adjustment mechanism 71, the VCT displacement angle is displaced toward the target displacement angle.

  The present invention can also be applied to the variable valve timing adjusting mechanism 71 of FIG. 13 configured as described above.

  Next, the configuration of the variable valve timing adjusting mechanism 72 according to the fourth embodiment of the present invention shown in FIG. 14 will be described focusing on differences from FIG. Also in FIG. 14, the same reference numerals are given to the same components as in FIG.

  First, in FIG. 1, there are two valves, an oil path switching valve for the advance / retard hydraulic control function 37 and an oil path switching valve for the drain switching control function 38. On the other hand, in FIG. 14, a single hydraulic control valve 60 is configured to achieve the advance / retard hydraulic pressure control function and the drain switching control function. For this purpose, the hydraulic pressure supply passages 28 and 29 are branched between the hydraulic pressure control valve 60 and the check valves 30 and 31, and are connected to the drain switching valves 34 and 35, respectively.

  In this configuration, during the holding operation for holding the VCT displacement angle at the target displacement angle, the control current of the hydraulic control valve 60 is controlled to a predetermined holding current, so that both the advance chamber 18 side and the retard chamber 19 side are controlled. The drain switching valves 34 and 35 are closed so that the check valves 30 and 31 on both the advance chamber 18 side and the retard chamber 19 side function effectively so that the hydraulic oil from the advance chamber 18 and the retard chamber 19 is discharged. Control is performed to prevent backflow, and the hydraulic pressure supplied to the variable valve timing adjustment mechanism 72 is controlled.

  On the other hand, during the advance / retard operation that displaces the VCT displacement angle in the advance direction or the retard direction, the control current of the hydraulic control valve 60 is controlled, and the advance chamber 18 side is controlled according to the displacement direction. Control is made so that either one of the check valves 30 or 31 does not function by opening one of the drain switching valves 34 or 35 on the retarding chamber 19 side, and the hydraulic pressure supplied to the variable valve timing adjusting mechanism 72 is variable. By doing so, the VCT displacement angle is displaced toward the target displacement angle.

  The present invention can also be applied to the variable valve timing adjusting mechanism 72 of FIG. 14 configured as described above.

It is a figure which shows roughly the variable valve timing adjustment mechanism in Example 1 of this invention, and its hydraulic control circuit. It is a figure for demonstrating retardation operation | movement, holding | maintenance operation | movement, and advance angle operation | movement of a variable valve timing adjustment mechanism. It is a characteristic view for demonstrating the difference in the VCT response speed at the time of advance operation by the presence or absence of a check valve. It is a characteristic view which shows an example of the response characteristic of a variable valve timing adjustment mechanism with a check valve. It is a time chart explaining the abnormality diagnosis method in Example 1 of the present invention (part 1). It is a time chart explaining the abnormality diagnosis method in Example 1 of the present invention (the 2). It is a flowchart explaining the flow of a process of the abnormality diagnosis routine of Example 1 of this invention (the 1). It is a flowchart explaining the flow of a process of the abnormality diagnosis routine of Example 1 of this invention (the 2). It is a flowchart explaining the flow of a process of the abnormality diagnosis routine of Example 1 of this invention (the 3). It is a time chart explaining the abnormality diagnosis method in Example 2 of this invention. It is a flowchart explaining the flow of a process of the abnormality diagnosis routine of Example 2 of this invention (the 1). It is a flowchart explaining the flow of a process of the abnormality diagnosis routine of Example 2 of this invention (the 2). It is a figure which shows roughly the variable valve timing adjustment mechanism in Example 3 of this invention, and its hydraulic control circuit. It is a figure which shows roughly the variable valve timing adjustment mechanism in Example 4 of this invention, and its hydraulic control circuit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Variable valve timing adjustment mechanism, 12 ... Housing, 14 ... Vane rotor, 16 ... Vane storage chamber, 17 ... Vane, 18 ... Advance chamber, 19 ... Delay chamber, 21 ... Hydraulic control valve, 24 ... Lock pin, 27 ... Oil pump, 28, 29 ... Hydraulic supply oil passage, 30, 31 ... Check valve, 32, 33 ... Drain oil passage, 34, 35 ... Drain switching valve, 37 ... Advance / retard hydraulic control function (first Hydraulic control valve), 38 ... drain switching control function (second hydraulic control valve), 43 ... ECU (abnormality diagnosis means), 60 ... hydraulic control valve, 71, 72 ... variable valve timing adjustment mechanism (VCT)

Claims (29)

A plurality of vane storage chambers formed in the housing of the vane type variable valve timing adjusting mechanism are divided into advance chambers and retard chambers by the vanes, respectively, and hydraulic supply oil for the advance chamber of at least one vane storage chamber Prevents backflow of hydraulic fluid from each hydraulic chamber ("hydraulic chamber" means either "advanced chamber" or "retarded chamber") in the hydraulic supply oil path of the passage and retarded chamber In addition to providing a check valve, a drain oil passage that bypasses the check valve is provided in parallel in each of the hydraulic supply oil passages of each hydraulic chamber, and a drain switching valve that is hydraulically driven is provided in each drain oil passage. A hydraulic switching valve that switches the hydraulic pressure that drives each drain switching valve;
During the holding operation for holding the displacement angle of the variable valve timing adjustment mechanism (hereinafter referred to as “VCT displacement angle”) at the target displacement angle, the advancement chamber side and retarding chamber side drain switching valves are closed to advance. The hydraulic switching valve is controlled so that the check valves on both the corner chamber side and the retard chamber side function effectively to prevent the backflow of hydraulic oil from both hydraulic chambers, and the hydraulic pressure of each hydraulic chamber The control current of the hydraulic control valve that controls the pressure is controlled to a predetermined holding current,
During advance / retard operation to displace the VCT displacement angle in the advance direction or retard direction, either the advance chamber side or the retard chamber side open the drain switching valve according to the displacement direction. The hydraulic switching valve is controlled so that one of the check valves does not function, and the control current of the hydraulic control valve is controlled to vary the hydraulic pressure in each hydraulic chamber, thereby setting the VCT displacement angle to the target displacement. In the abnormality diagnosis device of the vane type variable valve timing adjustment mechanism that is displaced toward the corner,
An abnormality diagnosing means for determining whether or not an opening abnormality has occurred during the holding operation, in which the drain switching valve and / or the check valve remains open based on a change amount of the VCT displacement angle within a predetermined period. An abnormality diagnosis device for a vane type variable valve timing adjustment mechanism characterized by comprising:   The abnormality diagnosis means calculates a difference between a VCT displacement angle immediately after the start of the holding operation and a VCT displacement angle when the predetermined period has elapsed, and based on this difference, opens the drain switching valve and / or the check valve. The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 1, wherein presence / absence of abnormality is determined.   The abnormality diagnosing means detects a maximum value and a minimum value of a VCT displacement angle from immediately after the start of the holding operation until the predetermined period elapses, and calculates a difference between them, and based on this difference, the drain switching valve and 2. The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 1, wherein presence / absence of an opening abnormality of the check valve is determined.   The abnormality diagnosis means detects a maximum value and a minimum value of a VCT displacement angle from immediately after the start of the holding operation until the predetermined period elapses, and a deviation between the target displacement angle and the maximum value during the holding operation and The deviation between the target displacement angle and the minimum value is calculated, and based on these two deviations, it is determined whether there is an abnormal opening of the drain switching valve and / or the check valve. The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 1. A plurality of vane storage chambers formed in the housing of the vane type variable valve timing adjusting mechanism are divided into advance chambers and retard chambers by the vanes, respectively, and hydraulic supply oil for the advance chamber of at least one vane storage chamber Prevents backflow of hydraulic fluid from each hydraulic chamber ("hydraulic chamber" means either "advanced chamber" or "retarded chamber") in the hydraulic supply oil path of the passage and retarded chamber In addition to providing a check valve, a drain oil passage that bypasses the check valve is provided in parallel in each of the hydraulic supply oil passages of each hydraulic chamber, and a drain switching valve that is hydraulically driven is provided in each drain oil passage. A hydraulic switching valve that switches the hydraulic pressure that drives each drain switching valve;
During the holding operation for holding the displacement angle of the variable valve timing adjustment mechanism (hereinafter referred to as “VCT displacement angle”) at the target displacement angle, the advancement chamber side and retarding chamber side drain switching valves are closed to advance. The hydraulic switching valve is controlled so that the check valves on both the corner chamber side and the retard chamber side function effectively to prevent the backflow of hydraulic oil from both hydraulic chambers, and the hydraulic pressure of each hydraulic chamber The control current of the hydraulic control valve that controls the pressure is controlled to a predetermined holding current,
During advance / retard operation to displace the VCT displacement angle in the advance direction or retard direction, either the advance chamber side or the retard chamber side open the drain switching valve according to the displacement direction. The hydraulic switching valve is controlled so that one of the check valves does not function, and the control current of the hydraulic control valve is controlled to vary the hydraulic pressure in each hydraulic chamber, thereby setting the VCT displacement angle to the target displacement. In the abnormality diagnosis device of the vane type variable valve timing adjustment mechanism that is displaced toward the corner,
An abnormality that determines whether or not the VCT displacement angle converges to the target displacement angle when the target displacement angle changes, and whether or not a closing abnormality in which the drain switching valve does not move is generated based on the convergence. An abnormality diagnosing device for a vane type variable valve timing adjusting mechanism, characterized by comprising a diagnostic means.   The abnormality diagnosing unit measures, as data representing the convergence, a time during which a state in which a deviation between the target displacement angle and the VCT displacement angle is a predetermined value or more continues, and based on the duration, the drain switching valve 6. The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 5, wherein the presence or absence of a closing abnormality is determined.   The abnormality diagnosing means until the deviation becomes equal to or smaller than a second predetermined value smaller than the first predetermined value after the deviation between the target displacement angle and the VCT displacement angle becomes equal to or larger than a first predetermined value. 6. The vane type variable valve timing adjustment according to claim 5, wherein the elapsed time is measured as data representing the convergence and whether or not the drain switching valve is closed abnormally is determined based on the elapsed time. Mechanism abnormality diagnosis device.   The vane according to any one of claims 5 to 7, wherein the abnormality diagnosis means determines the convergence on the precondition that a hydraulic pressure supplied to the hydraulic control valve is equal to or greater than a predetermined value. Abnormality diagnosis device of variable valve timing adjustment mechanism of the type.   9. The abnormality diagnosis unit according to claim 8, wherein whether or not a hydraulic pressure supplied to the hydraulic control valve is equal to or higher than a predetermined value is determined based on information related to an engine speed and / or an oil temperature. An abnormality diagnosis device for the vane variable valve timing adjustment mechanism.   10. The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 1, wherein the hydraulic pressure switching valve is integrated with the hydraulic pressure control valve. A plurality of vane storage chambers formed in a housing of a vane type variable valve timing adjustment mechanism (hereinafter referred to as “VCT”) are each divided into an advance chamber and a retard chamber by the vanes, and at least one A first check valve provided in a hydraulic supply oil passage of the advance chamber in the vane storage chamber for preventing the backflow of hydraulic oil from the advance chamber, and a first bypassing the first check valve The hydraulic oil from the retard chamber provided in the hydraulic supply oil passage of the first drain switching valve that is hydraulically driven and the retard chamber of the at least one vane storage chamber A second check valve for preventing back flow of the oil, a second drain switching valve driven by hydraulic pressure, provided in a second drain oil passage that bypasses the second check valve,
A first hydraulic control valve that controls the hydraulic pressure supplied to the VCT;
A second hydraulic control valve for controlling the hydraulic pressure for driving the first and second drain switching valves is provided,
During the holding operation for maintaining the displacement angle of the VCT at the target displacement angle, both the advance chamber side and the retard chamber side drain switching valves are closed to check both the advance chamber side and the retard chamber side. A first hydraulic pressure that controls the second hydraulic pressure control valve to control the hydraulic pressure supplied to the VCT and to control the second hydraulic pressure control valve so that the valve functions effectively to prevent the backflow of hydraulic oil from the advance angle chamber and the retard angle chamber. Control the control current of the control valve to a predetermined holding current,
During advance / retard operation to displace the VCT displacement angle in the advance direction or retard direction, either the advance chamber side or the retard chamber side open the drain switching valve according to the displacement direction. And controlling the second hydraulic control valve so that one of the check valves does not function, and controlling the control current of the first hydraulic control valve to vary the hydraulic pressure supplied to the VCT. In the abnormality diagnosis device for a vane-type variable valve timing adjustment mechanism that displaces the VCT displacement angle toward the target displacement angle,
An abnormality diagnosing means for determining whether or not an opening abnormality has occurred during the holding operation, in which the drain switching valve and / or the check valve remains open based on a change amount of the VCT displacement angle within a predetermined period. An abnormality diagnosis device for a vane type variable valve timing adjustment mechanism characterized by comprising:   The abnormality diagnosis means calculates a difference between a VCT displacement angle immediately after the start of the holding operation and a VCT displacement angle when the predetermined period has elapsed, and based on this difference, opens the drain switching valve and / or the check valve. The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 11, wherein presence / absence of abnormality is determined.   The abnormality diagnosing means detects a maximum value and a minimum value of a VCT displacement angle from immediately after the start of the holding operation until the predetermined period elapses, and calculates a difference between them, and based on this difference, the drain switching valve and The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 11, wherein presence / absence of an opening abnormality of the check valve is determined.   The abnormality diagnosis means detects a maximum value and a minimum value of a VCT displacement angle from immediately after the start of the holding operation until the predetermined period elapses, and a deviation between the target displacement angle and the maximum value during the holding operation and The deviation between the target displacement angle and the minimum value is calculated, and based on these two deviations, it is determined whether there is an abnormal opening of the drain switching valve and / or the check valve. 11. An abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to 11, A plurality of vane storage chambers formed in a housing of a vane type variable valve timing adjustment mechanism (hereinafter referred to as “VCT”) are each divided into an advance chamber and a retard chamber by the vanes, and at least one A first check valve provided in a hydraulic supply oil passage of the advance chamber in the vane storage chamber for preventing the backflow of hydraulic oil from the advance chamber, and a first bypassing the first check valve The hydraulic oil from the retard chamber provided in the hydraulic supply oil passage of the first drain switching valve that is hydraulically driven and the retard chamber of the at least one vane storage chamber A second check valve for preventing back flow of the oil, a second drain switching valve driven by hydraulic pressure, provided in a second drain oil passage that bypasses the second check valve,
A first hydraulic control valve that controls the hydraulic pressure supplied to the VCT;
A second hydraulic control valve for controlling the hydraulic pressure for driving the first and second drain switching valves is provided,
During the holding operation for maintaining the displacement angle of the VCT at the target displacement angle, both the advance chamber side and the retard chamber side drain switching valves are closed to check both the advance chamber side and the retard chamber side. A first hydraulic pressure that controls the second hydraulic pressure control valve to control the hydraulic pressure supplied to the VCT and to control the second hydraulic pressure control valve so that the valve functions effectively to prevent the backflow of hydraulic oil from the advance angle chamber and the retard angle chamber. Control the control current of the control valve to a predetermined holding current,
During advance / retard operation to displace the VCT displacement angle in the advance direction or retard direction, either the advance chamber side or the retard chamber side open the drain switching valve according to the displacement direction. And controlling the second hydraulic control valve so that one of the check valves does not function, and controlling the control current of the first hydraulic control valve to vary the hydraulic pressure supplied to the VCT. In the abnormality diagnosis device for a vane-type variable valve timing adjustment mechanism that displaces the VCT displacement angle toward the target displacement angle,
An abnormality that determines whether or not the VCT displacement angle converges to the target displacement angle when the target displacement angle changes, and whether or not a closing abnormality in which the drain switching valve does not move is generated based on the convergence. An abnormality diagnosing device for a vane type variable valve timing adjusting mechanism, characterized by comprising a diagnostic means.   The abnormality diagnosing unit measures, as data representing the convergence, a time during which a state in which a deviation between the target displacement angle and the VCT displacement angle is a predetermined value or more continues, and based on the duration, the drain switching valve 16. The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 15, wherein the presence or absence of a closing abnormality is determined.   The abnormality diagnosing means until the deviation becomes equal to or smaller than a second predetermined value smaller than the first predetermined value after the deviation between the target displacement angle and the VCT displacement angle becomes equal to or larger than a first predetermined value. 16. The vane type variable valve timing adjustment according to claim 15, wherein the elapsed time is measured as data representing the convergence and whether or not the drain switching valve is closed abnormally is determined based on the elapsed time. Mechanism abnormality diagnosis device.   18. The vane according to claim 15, wherein the abnormality diagnosis unit determines the convergence on the precondition that a hydraulic pressure supplied to the hydraulic control valve is equal to or greater than a predetermined value. Abnormality diagnosis device of variable valve timing adjustment mechanism of the type.   19. The abnormality diagnosing means determines whether or not the hydraulic pressure supplied to the hydraulic control valve is equal to or higher than a predetermined value based on information related to an engine speed and / or oil temperature. An abnormality diagnosis device for the vane variable valve timing adjustment mechanism.   The vane type variable valve timing adjusting mechanism according to any one of claims 11 to 19, wherein a shaft for driving the first hydraulic control valve and the second hydraulic control valve is integrated. Abnormality diagnosis device. A plurality of vane storage chambers formed in a housing of a vane type variable valve timing adjustment mechanism (hereinafter referred to as “VCT”) are each divided into an advance chamber and a retard chamber by the vanes, and at least one A first check valve provided in a hydraulic supply oil passage of the advance chamber in the vane storage chamber for preventing the backflow of hydraulic oil from the advance chamber, and a first bypassing the first check valve The hydraulic oil from the retard chamber provided in the hydraulic supply oil passage of the first drain switching valve that is hydraulically driven and the retard chamber of the at least one vane storage chamber A second check valve for preventing back flow of the oil, a second drain switching valve driven by hydraulic pressure, provided in a second drain oil passage that bypasses the second check valve,
A first hydraulic control valve that controls the first and second drain switching valves and the hydraulic pressure supplied to the VCT;
During the holding operation of holding the displacement angle of the VCT at the target displacement angle, the control current of the hydraulic control valve is controlled to a predetermined holding current, and the drain switching valves on both the advance chamber side and the retard chamber side are turned on. Control is performed so that the check valves on both the advance angle chamber side and the retard angle chamber side are effectively functioned to prevent the backflow of hydraulic oil from the advance angle chamber and the retard angle chamber, and supplied to the VCT. Control the hydraulic pressure,
During the advance / retard operation for displacing the VCT displacement angle in the advance direction or the retard direction, the control current of the hydraulic control valve is controlled, and the advance chamber side and the retard angle are controlled according to the displacement direction. Either one of the chamber side drain switching valves is opened so that either one of the check valves does not function, and the hydraulic pressure supplied to the VCT is varied to direct the VCT displacement angle to the target displacement angle. In the abnormality diagnosis device of the vane type variable valve timing adjustment mechanism that is controlled to be displaced by
An abnormality diagnosing means for determining whether or not an opening abnormality has occurred during the holding operation, in which the drain switching valve and / or the check valve remains open based on a change amount of the VCT displacement angle within a predetermined period. An abnormality diagnosis device for a vane type variable valve timing adjustment mechanism characterized by comprising:   The abnormality diagnosis means calculates a difference between a VCT displacement angle immediately after the start of the holding operation and a VCT displacement angle when the predetermined period has elapsed, and based on this difference, opens the drain switching valve and / or the check valve. The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 21, wherein the presence or absence of abnormality is determined.   The abnormality diagnosing means detects a maximum value and a minimum value of a VCT displacement angle from immediately after the start of the holding operation until the predetermined period elapses, and calculates a difference between them, and based on this difference, the drain switching valve and The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 21, wherein the presence / absence of an opening abnormality of the check valve is determined.   The abnormality diagnosis means detects a maximum value and a minimum value of a VCT displacement angle from immediately after the start of the holding operation until the predetermined period elapses, and a deviation between the target displacement angle and the maximum value during the holding operation and The deviation between the target displacement angle and the minimum value is calculated, and based on these two deviations, it is determined whether there is an abnormal opening of the drain switching valve and / or the check valve. The abnormality diagnosis device for a vane type variable valve timing adjustment mechanism according to claim 21. A plurality of vane storage chambers formed in a housing of a vane type variable valve timing adjustment mechanism (hereinafter referred to as “VCT”) are each divided into an advance chamber and a retard chamber by the vanes, and at least one A first check valve provided in a hydraulic supply oil passage of the advance chamber in the vane storage chamber for preventing the backflow of hydraulic oil from the advance chamber, and a first bypassing the first check valve The hydraulic oil from the retard chamber provided in the hydraulic supply oil passage of the first drain switching valve that is hydraulically driven and the retard chamber of the at least one vane storage chamber A second check valve for preventing back flow of the oil, a second drain switching valve driven by hydraulic pressure, provided in a second drain oil passage that bypasses the second check valve,
A first hydraulic control valve that controls the first and second drain switching valves and the hydraulic pressure supplied to the VCT;
During the holding operation for maintaining the displacement angle of the VCT at the target displacement angle, both the advance chamber side and the retard chamber side drain switching valves are closed to check both the advance chamber side and the retard chamber side. The hydraulic switching valve is controlled so that the valve functions effectively to prevent backflow of hydraulic oil from both hydraulic chambers, and the control current of the hydraulic control valve that controls the hydraulic pressure of each hydraulic chamber is held at a predetermined level. Control to current,
During advance / retard operation to displace the VCT displacement angle in the advance direction or retard direction, either the advance chamber side or the retard chamber side open the drain switching valve according to the displacement direction. The hydraulic switching valve is controlled so that one of the check valves does not function, and the control current of the hydraulic control valve is controlled to vary the hydraulic pressure in each hydraulic chamber, thereby setting the VCT displacement angle to the target displacement. In the abnormality diagnosis device of the vane type variable valve timing adjustment mechanism that is displaced toward the corner,
An abnormality that determines whether or not the VCT displacement angle converges to the target displacement angle when the target displacement angle changes, and whether or not a closing abnormality in which the drain switching valve does not move is generated based on the convergence. An abnormality diagnosing device for a vane type variable valve timing adjusting mechanism, characterized by comprising a diagnostic means.   The abnormality diagnosing unit measures, as data representing the convergence, a time during which a state in which a deviation between the target displacement angle and the VCT displacement angle is a predetermined value or more continues, and based on the duration, the drain switching valve 26. The abnormality diagnosis apparatus for a vane type variable valve timing adjustment mechanism according to claim 25, wherein the presence or absence of a closing abnormality is determined.   The abnormality diagnosing means until the deviation becomes equal to or smaller than a second predetermined value smaller than the first predetermined value after the deviation between the target displacement angle and the VCT displacement angle becomes equal to or larger than a first predetermined value. 26. The vane-type variable valve timing adjustment according to claim 25, wherein the elapsed time is measured as data representing the convergence, and whether or not the drain switching valve is closed abnormally is determined based on the elapsed time. Mechanism abnormality diagnosis device.   The vane according to any one of claims 25 to 27, wherein the abnormality diagnosis means determines the convergence on the precondition that a hydraulic pressure supplied to the hydraulic control valve is equal to or greater than a predetermined value. Abnormality diagnosis device of variable valve timing adjustment mechanism of the type.   29. The abnormality diagnosis unit according to claim 28, wherein the abnormality diagnosis unit determines whether or not a hydraulic pressure supplied to the hydraulic control valve is equal to or higher than a predetermined value based on information related to an engine speed and / or an oil temperature. An abnormality diagnosis device for the vane variable valve timing adjustment mechanism.

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