JP2008008283A - Control device of vane type variable valve timing adjusting mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the actual valve timing from varying by influence of an operation state of a variable valve lift mechanism VVL, in a vane type variable valve timing adjusting mechanism VCT. <P>SOLUTION: When switching a control mode of the VVL in the direction for reducing supply hydraulic pressure of the VCT, the target valve timing and an OCV current value (a control current value of a hydraulic control valve) are respectively restricted by an ignition timing delay side guard value, and are controlled in a state of making an ignition timing advance chamber side check valve function by restricting a control area of the VCT in an area for closing an ignition timing advance chamber side drain switching valve by putting the VCT in a state of not substantially performing ignition timing delay operation. While, when switching the control mode of the VVL in the direction for increasing the supply hydraulic pressure to the VCT, the target valve timing and the OCV current value are respectively restricted by an ignition timing advance side guard value, and are put in a state of making an ignition timing delay chamber side check valve function by restricting the control area of the VCT in an area for closing an ignition timing delay chamber side drain switching valve by putting the VCT in a state of not substantially performing ignition timing advance operation. <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. This invention relates to a mechanism control device.

  In recent years, in internal combustion engines (engines) mounted on vehicles, variable valve timing that varies the valve timing (cam shaft displacement angle) of intake valves and exhaust valves for the purpose of improving output, reducing fuel consumption, and reducing exhaust emissions. The number of machines that employ adjustment mechanisms is increasing. For example, the basic configuration of a vane type variable valve timing adjustment mechanism is, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2001-159330), a housing that rotates in synchronization with an engine crankshaft, an intake valve ( Or a vane rotor connected to a camshaft of an exhaust valve) is coaxially arranged, and a plurality of vane storage chambers formed in the housing are advanced and retarded chambers by vanes (blade portions) on the outer periphery side of the vane rotor. Divide into 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 adjustment mechanism, when the intake valve or exhaust valve is driven to open or close during engine operation, the fluctuation of the friction torque received by the camshaft from the intake valve or exhaust valve is transmitted to the vane rotor, thereby 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.

  In the variable valve timing adjusting mechanism of Patent Document 2, a check valve is provided in each of the hydraulic supply oil passage in the advance chamber and the hydraulic supply oil passage in the retard chamber, and each of the hydraulic supply oil passages in each hydraulic chamber is provided in each hydraulic chamber. A drain oil passage that bypasses the check valve is provided in parallel, and a hydraulic control valve (spool solenoid valve) that controls the hydraulic pressure supplied to each hydraulic chamber serves as a drain switching valve that opens and closes the drain oil passage in each hydraulic chamber. It has a configuration with integrated functions. Then, by controlling the drive current 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 drain oil passage of each hydraulic chamber is controlled, and any hydraulic chamber is controlled. When it is necessary to release the hydraulic pressure, the drain oil passage of the hydraulic chamber is opened so that the hydraulic pressure can be quickly released through the drain oil passage.

In recent internal combustion engines, in addition to the variable valve timing adjustment mechanism, a hydraulically driven variable valve lift mechanism that changes the valve lift amount of the intake valve and exhaust valve is installed for the purpose of further performance improvement. There is something.
JP 2001-159330 A (pages 4 to 6 etc.) JP 2003-106115 A (first page, etc.)

  However, in the above-described system that supplies hydraulic pressure with a common hydraulic pressure supply source to both the variable valve timing adjustment mechanism with a check valve and the variable valve lift mechanism, the variable valve lift mechanism supplies the variable valve lift mechanism with lift control. When the oil pressure changes, the oil pressure supplied to the variable valve timing adjusting mechanism varies under the influence thereof, and the actual valve timing (actual displacement angle of the camshaft) may fluctuate.

  Specifically, as shown in FIG. 8 (b), during the retarding operation of the variable valve timing adjustment mechanism (VCT), the retarding angle is prevented in order to prevent backflow of hydraulic oil from the retarding chamber, as shown in FIG. In order to close the drain switch valve on the chamber side so that the check valve on the retard chamber side functions, and to smoothly discharge the hydraulic oil from the advance chamber, the drain switch valve on the advance chamber side The valve is opened and controlled so that the check valve on the advance angle chamber side does not function. During this retarding operation, the hydraulic pressure supplied to the variable valve timing adjustment mechanism due to the lift control of the variable valve lift mechanism (VVL) When the pressure decreases, since the check valve on the advance chamber side does not function due to the retard control, as shown in FIG. 9B, the hydraulic pressure in the advance chamber temporarily decreases suddenly. There is a possibility that the actual valve timing temporarily fluctuates in the retarding direction.

  On the other hand, as shown in FIG. 8 (c), during advance operation of the variable valve timing adjustment mechanism, in order to prevent backflow of hydraulic oil from the advance chamber, the drain switch valve on the advance chamber side is closed. In order to make the check valve on the advance chamber side function, and to smoothly discharge the hydraulic oil from the retard chamber, the drain switch valve on the retard chamber side is opened and the retard chamber side is opened. The check valve is controlled so as not to function, but during this advance operation, if the hydraulic pressure supplied to the variable valve timing adjustment mechanism rises due to the lift control of the variable valve lift mechanism, the advance valve controls the retard chamber. Since the check valve on the side does not function, as shown in FIG. 10 (c), the hydraulic pressure in the retarded chamber temporarily decreases suddenly due to the hydraulic pressure in the advanced chamber, and the actual valve timing temporarily changes. There is a possibility that it will fluctuate in the advance direction.

  Even in the case of a system in which the hydraulic circuit of the variable valve timing adjustment mechanism with a check valve described above and the hydraulic circuit of the variable valve lift mechanism are separated, the torque of the camshaft fluctuates due to lift control of the variable valve lift mechanism. As a result, hydraulic oil may be pushed out from the hydraulic chamber on the side where the check valve of the variable valve timing adjusting mechanism is not functioning, and the actual valve timing may fluctuate.

  The present invention has been made in consideration of these circumstances. Therefore, the purpose of the present invention is to determine the actual valve timing due to the influence of the hydraulic pressure supplied to the variable valve timing adjustment mechanism and the operating state of the elements that vary the torque of the camshaft. It is an object of the present invention to provide a control device for a vane type variable valve timing adjustment mechanism that can prevent fluctuation and can realize stable valve timing control.

  In order 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 adjustment mechanism (hereinafter referred to as “VCT”) are advanced by the vanes. Each chamber is divided into a corner chamber and a retard chamber, and each of the hydraulic chambers (“hydraulic chamber” is referred to as “advanced chamber”) in each of the advance chamber and the retard chamber chamber of at least one vane storage chamber. A check valve is provided to prevent backflow of hydraulic oil from the “corner chamber” and “retard chamber”, and the check valve is bypassed in the hydraulic oil supply passage of each hydraulic chamber. In the control device of the vane type variable valve timing adjusting mechanism in which the drain oil passages are provided in parallel and each drain oil passage is provided with a drain switching valve, the actual displacement angle of the VCT is made to coincide with the target displacement angle by the control means. hydraulic Control the control valve to vary the hydraulic pressure in each hydraulic chamber and control the opening and closing of the drain switching valve in each hydraulic chamber to switch between the state where the check valve in each hydraulic chamber is functioning and the state where it is not functioning, The actual displacement angle of the VCT is determined based on the operating state of the hydraulic pressure supplied to the VCT by the timing fluctuation prevention control means and / or the element that varies the camshaft torque of the internal combustion engine (hereinafter referred to as “hydraulic / camshaft torque fluctuation element”). Valve timing fluctuation prevention control for controlling the state of the drain switching valve and the check valve in each hydraulic chamber so as to prevent fluctuation is executed.

  In this way, even if the hydraulic pressure or camshaft torque supplied to the VCT fluctuates due to the operating state of the hydraulic pressure / camshaft torque fluctuation element, fluctuations in the actual displacement angle of the VCT caused by the fluctuations are prevented. In addition, the state of the check valve on the advancing chamber side and the retarding chamber side (that is, the open / close state of the drain switching valve) can be controlled, so the actual valve timing is affected by the operating state of the hydraulic and camshaft torque fluctuation elements. Fluctuation can be prevented and stable valve timing control can be realized.

  According to a second aspect of the present invention, there is provided a system including a hydraulically driven variable valve lift mechanism for changing a valve lift amount of an intake valve and / or an exhaust valve of an internal combustion engine as a hydraulic pressure / camshaft torque fluctuation element. It may be applied. In this way, in a system equipped with a VCT and a variable valve lift mechanism, it is possible to prevent the actual valve timing from fluctuating due to the influence of the operation state of the variable valve lift mechanism, and it depends on the operation state of the variable valve lift mechanism. Therefore, stable valve timing control can be realized.

  Further, when the VCT is advanced as in claim 3, the advance chamber side drain switching valve for allowing the hydraulic oil to flow in is closed to function the advance chamber side check valve, and the hydraulic oil is When the drain switching valve on the retarding chamber side to be discharged is opened and the check valve on the retarding chamber side is controlled so as not to function and the VCT is retarded, the drain on the retarding chamber side into which hydraulic oil flows is supplied. When the control valve is closed so that the check valve on the retard chamber side functions and the drain switch valve on the advance chamber side from which hydraulic fluid is discharged is opened so that the check valve on the advance chamber side does not function good.

  In this way, even in the low rotation region where the hydraulic pressure supplied from the hydraulic pressure supply source is low, the reverse flow of oil from the advance chamber is reversed against the torque fluctuation in the retard direction of the vane rotor during the advance operation. While preventing by a stop valve, hydraulic pressure can be efficiently supplied to the advance chamber to improve the advance angle response. Similarly, during the retard operation, the retard angle against the torque fluctuation in the advance direction of the vane rotor is retarded. While preventing back flow of oil from the chamber by a check valve, the hydraulic pressure can be efficiently supplied to the retard chamber and the retard response can be improved.

  Further, when holding the actual displacement angle of the VCT at the target displacement angle, both the advance angle chamber side and the retard angle chamber side drain switching valves are closed and both the advance angle chamber side and the retard angle chamber side are closed. It is preferable to control the check valve to function. In this way, even if torque fluctuations acting on the vane rotor in the retarding direction and the advancement direction act on the vane rotor due to the torque fluctuations received by the camshaft from the intake valve or the exhaust valve, The backflow of the hydraulic oil can be prevented by the check valve, the hydraulic pressure for holding the vane from both sides can be prevented from being lowered, and the holding stability can be improved.

  In this case, the specific control method of the valve timing fluctuation prevention control is to prevent the valve timing fluctuation by limiting the target displacement angle of the VCT based on the operation state of the hydraulic pressure / camshaft torque fluctuation element as in claim 5. You may make it perform control.

  For example, when the hydraulic pressure supplied to the VCT decreases due to the influence of the operating state of the hydraulic pressure / camshaft torque fluctuation element, the target displacement angle of the VCT is limited by the retard side guard value, and the VCT hardly operates at a retarded angle. By doing so, the control region of the VCT is limited to a region where the drain switching valve on the advance chamber side is closed, and the check valve on the advance chamber side is controlled to function. As a result, even if the hydraulic pressure supplied to the VCT drops due to the influence of the operating state of the hydraulic pressure / camshaft torque fluctuation element, the check valve on the advance chamber side temporarily reduces the hydraulic pressure in the advance chamber temporarily. To prevent the actual valve timing from temporarily changing in the retarding direction.

  On the other hand, when the hydraulic pressure supplied to the VCT rises due to the influence of the operating state of the hydraulic pressure / camshaft torque fluctuation element, the VCT is hardly advanced by limiting the target displacement angle of the VCT with the advance side guard value. By doing so, the control region of the VCT is limited to a region in which the drain switching valve on the retarding chamber side is closed, and is controlled so that the check valve on the retarding chamber side functions. As a result, even if the hydraulic pressure supplied to the VCT rises due to the influence of the operating state of the hydraulic pressure / camshaft torque fluctuation element, it is possible to delay This is prevented by a check valve on the chamber side, and the actual valve timing is prevented from temporarily changing in the advance direction.

  In general, in the control of VCT, the control current of the hydraulic control valve is controlled so that the deviation between the target displacement angle and the actual displacement angle is small. Therefore, the target displacement angle is limited by the advance side guard value or the retard side guard value. However, if the deviation between the target displacement angle after the restriction and the actual displacement angle is relatively large, the advance angle operation or the retard angle operation is continued until the deviation becomes sufficiently small. There is a possibility that (the open / close state of the drain switching valve) cannot be switched quickly.

  Therefore, as described in claim 6, valve timing fluctuation prevention control is performed by limiting the VCT control input (for example, control current of the hydraulic control valve, control duty, etc.) based on the operating state of the hydraulic pressure / camshaft torque fluctuation element. May be executed. For example, when the hydraulic pressure supplied to the VCT decreases due to the influence of the operating state of the hydraulic pressure / camshaft torque fluctuation element, the control input corresponding to the deviation between the target displacement angle of the VCT and the actual displacement angle is set to the retard side guard value. Thus, the control region of the VCT is quickly restricted to a region where the drain switching valve on the advance chamber side is closed, and the check valve on the advance chamber side is controlled to function.

  On the other hand, when the hydraulic pressure supplied to the VCT increases due to the influence of the operating state of the hydraulic pressure / camshaft torque fluctuation element, the control input corresponding to the deviation between the target displacement angle and the actual displacement angle of the VCT is set to the advance side guard value. Thus, the control region of the VCT is quickly limited to a region where the drain switching valve on the retarding chamber side is closed and controlled so that the check valve on the retarding chamber side functions. In this way, even when the deviation between the target displacement angle and the actual displacement angle is relatively large, the state of the check valve can be quickly switched.

  In addition, although the above-mentioned claim 5 and claim 6 may be carried out independently, the both are combined, and as in claim 7, based on the operating state of the hydraulic pressure / camshaft torque fluctuation element, The valve timing variation prevention control may be executed by limiting the target displacement angle and limiting the control input of the VCT. Thereby, a more reliable valve timing fluctuation preventing effect can be obtained.

  Further, the valve timing fluctuation prevention control may be permitted when the deviation between the target displacement angle of the VCT and the actual displacement angle is equal to or greater than a predetermined value. In other words, when the deviation between the target displacement angle and the actual displacement angle of the VCT is greater than or equal to a predetermined value and the VCT is advanced or retarded, the check valve on the retard chamber side or the advance chamber side is not functioned. Therefore, it is determined that the actual valve timing may vary due to the influence of the operating state of the hydraulic pressure / camshaft torque variation element, and the valve timing variation prevention control is permitted. In this way, the actual valve timing may fluctuate when the check valve on the retard chamber side or the advance chamber side is disabled (that is, the effect of the operating state of the hydraulic pressure / cam shaft torque variation element). The valve timing fluctuation prevention control can be executed only when there is.

  Generally, the hydraulic control valve is composed of a solenoid valve driven by a solenoid and requires electrical wiring. Therefore, this hydraulic control valve is provided inside the VCT that rotates at high speed in synchronization with the crankshaft of the engine. Is virtually impossible. In this relation, since the hydraulic control valve is arranged outside the VCT, as in Patent Document 2, in the configuration in which the drain oil passage of each hydraulic chamber is opened and closed by the hydraulic control valve, the drain oil passage from each hydraulic chamber. There is a disadvantage that the length of the oil path (oil path that is always in communication with the hydraulic chamber) to the hydraulic control valve that opens and closes the valve becomes longer, and the response becomes slower accordingly.

  In order to eliminate this drawback, as in claim 9, the drain switching valve of each hydraulic chamber is configured to be hydraulically driven and provided inside the housing of the VCT, and the hydraulic pressure for driving each drain switching valve. It is preferable to provide a hydraulic switching valve for switching between and outside the housing of the VCT. In this configuration, the drain switching valve can be reduced in size, and electrical wiring to the drain switching valve is not required. Therefore, the drain switching valve can be assembled together with the check valve in a narrow space inside the VCT. The design flexibility is increased, and a drain switching valve can be arranged near each hydraulic chamber, and the drain oil path can be opened / closed close to the hydraulic chamber with good response during advance / retard operation. There is.

  In this case, the hydraulic pressure switching valve for switching the hydraulic pressure for driving the drain switching valve may be provided separately from the hydraulic pressure control valve. However, as in claim 10, the hydraulic pressure switching valve is integrated with the hydraulic pressure control valve. It is good to have the configuration. Thereby, the request | requirement of part number reduction, cost reduction, and compactization 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 aspect.
For example, as in claim 10, the advance chamber is provided in a hydraulic supply oil passage of an advance chamber in at least one vane storage chamber of a vane type variable valve timing adjustment mechanism (hereinafter referred to as "VCT"). A first check valve that prevents backflow of hydraulic oil from the first drain valve, a first drain control valve that is provided in a first drain oil passage that bypasses the first check valve, and is hydraulically driven; A second check valve that is provided in a hydraulic pressure oil passage of the retard chamber of at least one vane storage chamber and prevents the backflow of hydraulic oil from the retard chamber, and bypasses the second check valve A second drain control valve provided in the second drain oil passage and driven by hydraulic pressure; a first hydraulic control valve for controlling a hydraulic pressure supplied to the VCT; the first drain control valve; 2 which controls the hydraulic pressure which drives 2 drain hydraulic valves And pressure control valve may be configured to include a control means for controlling said first hydraulic pressure control valve and the second hydraulic control valve.

  The present invention according to claims 1 to 10 can be applied to the VCT having such a configuration (claims 11 to 21).

  Further, as in claim 22, the first check valve for preventing the backflow of the hydraulic oil from the advance chamber to the hydraulic supply oil passage of the advance chamber in at least one vane storage chamber of the VCT, A first drain oil passage that bypasses the first check valve is provided, and backflow of hydraulic oil from the retard chamber is prevented in the hydraulic supply oil passage of the retard chamber of at least one vane storage chamber. A second drain valve that bypasses the second check valve and the second check valve is provided, and the hydraulic control valve that controls the hydraulic pressure supplied to the VCT includes the first drain oil path and the The drain oil passage control function for opening / closing the second drain oil passage may be integrated.

  The present invention according to claims 1 to 8 can also be applied to the VCT having such a configuration (claims 22 to 29).

  In this case, as in claim 30, the first drain control valve that is hydraulically driven to the first drain oil passage and the second drain control valve that is hydraulically driven to the second drain oil passage. And opening / closing the first drain oil passage by opening / closing the first drain control valve by hydraulic control by the drain oil passage control function of the hydraulic control valve, and The second drain oil passage may be opened / closed by opening / closing the second drain control valve.

  Further, according to a thirty-first aspect, each of the drain control valves is provided inside the housing of the VCT, and the hydraulic control valve for switching a hydraulic pressure for driving the drain control valves is provided outside the housing of the VCT. A configuration is good. Since each drain control valve does not require electrical wiring, it can be compactly assembled to the vane rotor inside the VCT together with each check valve. A drain control valve is arranged near each hydraulic chamber, and the advance angle・ Each drain oil passage can be opened / closed with good response near each hydraulic chamber during retarding operation.

Hereinafter, an embodiment 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 (drain control valves) 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, they are compactly assembled together with the check valves 30 and 31 to the vane rotor 14 inside the housing 12 of 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 (hydraulic switching valve) for switching the hydraulic pressure for driving the switching valves 34 and 35 is integrated. The hydraulic control valve 21 is provided outside the housing 12 of the variable valve timing adjustment mechanism 11 because electrical wiring is necessary. 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 controls the control current of the hydraulic control valve 21 of the variable valve timing adjustment mechanism 11 so as to make the actual valve timing coincide with the target valve timing by executing a VCT control routine of FIG. 11 described later. 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 the 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 this embodiment, a check valve 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. 30 and 31, and 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. In addition, drain switching valves 34 and 35 are provided, 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. The valve 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 switch valve 38 to the drain switch valve 35 of the retard chamber 19, thereby draining the retard chamber 19. 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 holding the actual valve timing at the target valve timing, both the drain switching can be performed by applying hydraulic pressure from the hydraulic switching valve 38 to the drain switching valves 34 and 35 of both the advance chamber 18 and the retard chamber 19. The valves 34 and 35 are both 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, both the advance chamber 18 and the retard chamber 19 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 switch valve 38 to the drain switch 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 of the variable valve timing adjustment mechanism 11 (hereinafter referred to as “VCT”) will be described with reference to FIG. FIG. 4 shows an example of a VCT response characteristic obtained by measuring the relationship between the control current value of the hydraulic control valve 21 (hereinafter referred to as “OCV”) and the VCT response speed.

  In this 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. In the VCT response characteristics of FIG. 4, the responsiveness sudden change point on the retarded angle side is a point at which the drain switching valve 34 of the advance chamber 18 is closed / opened, and the sudden response point on the advanced angle side is This is a point that the valve closing / opening of the drain switching valve 35 of the retarding chamber 19 is switched. The holding operation is performed in a region where the gradient of the change in the VCT response speed between the responsiveness sudden change point on the retard side and the responsive sudden change point on the advance side is small.

  As shown in FIG. 1, a hydraulically driven variable valve lift mechanism 46 (hereinafter referred to as “VVL”) is provided, and the valve lift amount of the intake valve (or exhaust valve) is varied by the VVL 46. In the present embodiment, hydraulic pressure is supplied to the VVL 46 and the VCT 11 described above by a common oil pump 27.

  The configuration of the VVL 46 will be described based on FIG. A cam shaft 48 for driving an intake valve or an exhaust valve (hereinafter simply referred to as a “valve”) 47 is provided with a low lift cam 49 and a high lift cam 50 that are different in cam profile and are integrally rotatable. ing. A rocker shaft 51 is provided below the camshaft 48, and a rocker arm 52 is provided so as to be swingable in the vertical direction with the rocker shaft 51 as a support shaft. The top end portion of the rocker arm 52 is in contact with the upper end portion of the valve 47, and the valve 47 is lifted in the vertical direction by the rocking movement of the rocker arm 52 in the vertical direction.

  Further, the rocker arm 52 has a low lift cam pressing portion (not shown) pressed against the low lift cam 49 and a high lift cam pressing portion pressed against the high lift cam 50. (Not shown). The low lift cam 49 is formed with an outer peripheral surface shape so that the pressing amount of the rocker arm 52 (low lift cam pressing portion) is reduced and the pressing period is shortened, and the high lift cam 50 is provided with the rocker arm 52 (high The outer peripheral surface shape is formed so that the pressing amount of the lift cam pressing portion) increases and the pressing period becomes longer.

  Further, the rocker arm 52 is provided with a hydraulically driven cam switching mechanism 53. The cam switching mechanism 53 includes a low lift cam effective state in which the rocker arm 52 (low lift cam pressing portion) is pressed by the low lift cam 49 to drive the valve 47, and the rocker arm 52 (high The lift cam pressing portion) is pressed to switch between a high lift cam effective state in which the valve 47 is driven.

  When the control mode of the VVL 46 is switched to the low lift mode in which the lift amount of the valve 47 is reduced, the hydraulic pressure supplied to the cam switching mechanism 53 is decreased by a hydraulic control valve (not shown) to make the cam switching mechanism 53 a low lift cam. The valve 47 is driven by switching to the effective state and pressing the rocker arm 52 (low lift cam pressing portion) with the low lift cam 49. As a result, the pressing amount of the rocker arm 52 is reduced, the lift amount of the valve 47 is reduced, the pressing period of the rocker arm 52 is shortened, and the valve opening period of the valve 47 is shortened.

  On the other hand, when the control mode of the VVL 46 is switched to the high lift mode in which the lift amount of the valve 47 is increased, the hydraulic pressure supplied to the cam switching mechanism 53 is increased by the hydraulic control valve to make the cam switching mechanism 53 a high lift cam. The valve 47 is driven by switching to the effective state and pressing the rocker arm 52 (high lift cam pressing portion) with the high lift cam 50. As a result, the pressing amount of the rocker arm 52 is increased and the lift amount of the valve 47 is increased, and the pressing period of the rocker arm 52 is increased and the valve opening period of the valve 47 is increased.

  The ECU 43 controls the hydraulic control valve of the VVL 46 in accordance with the engine operating state (for example, the engine rotation speed, the engine load, etc.), and switches the control mode of the VVL 46 between the low lift mode and the high lift mode.

  In the above-described system for supplying hydraulic pressure with the oil pump 27 common to both the VCT 11 and the VVL 46, when the hydraulic pressure supplied to the VVL 46 is changed by switching the control mode of the VVL 46, the hydraulic pressure supplied to the VCT 11 is affected by the change. there is a possibility.

  In a conventional VCT without a check valve, as shown in FIGS. 6A and 6B, when the hydraulic pressure supplied to the VCT fluctuates due to the switching of the control mode of the VVL 46 during steady state (during holding operation). The actual valve timing (actual cam shaft displacement angle) may temporarily vary.

  On the other hand, in the VCT 11 with a check valve according to the present embodiment, both the drain switching valves 34 and 35 are closed during normal operation (during holding operation), and the advance chamber 18 and the retard chamber 19 are closed. Therefore, even if the hydraulic pressure supplied to the VCT 11 fluctuates due to the influence of switching of the control mode of the VVL 46, as shown in FIGS. 7 (a) and 7 (b). Actual valve timing hardly fluctuates.

  However, as shown in FIG. 8B, during the retard operation of the VCT 11, in order to prevent the backflow of oil from the retard chamber 19, the drain switching valve 35 on the retard chamber 19 side is closed. In order to keep the check valve 31 on the retard chamber 19 side from functioning and to smoothly discharge the hydraulic oil from the advance chamber 18, the drain switching valve 34 on the advance chamber 18 side is opened to advance. The check valve 30 on the chamber 18 side is controlled so as not to function. During this retarding operation, when the control mode of the VVL 46 is switched from the low lift mode to the high lift mode and the hydraulic pressure supplied to the VCT 11 decreases, Since the check valve 30 on the advance angle chamber 18 side does not function due to the retard control, the hydraulic pressure in the advance angle chamber 18 temporarily decreases as shown in FIG. There is a possibility that the timing may fluctuate temporarily That.

  As shown in FIGS. 8A and 9A, during the advance operation of the VCT 11, the control mode of the VVL 46 is switched from the low lift mode to the high lift mode, and the hydraulic pressure supplied to the VCT 11 decreases. In this case, the actual valve timing hardly fluctuates.

  On the other hand, as shown in FIG. 8 (c), during advance operation of the VCT 11, in order to prevent the backflow of oil from the advance chamber 18, the drain switching valve 34 on the advance chamber 18 side is closed. In order to put the check valve 30 on the advance chamber 18 into a functioning state and to smoothly discharge the hydraulic oil from the retard chamber 19, the drain switching valve 35 on the retard chamber 19 side is opened to retard. The check valve 31 on the chamber 19 side is controlled so as not to function. During this advance operation, when the control mode of the VVL 46 is switched from the high lift mode to the low lift mode and the hydraulic pressure supplied to the VCT 11 rises, Since the check valve 31 on the retarding chamber 19 side does not function due to the advance control, the hydraulic pressure in the retarding chamber 19 is temporarily increased by the increase in the hydraulic pressure in the advance chamber 18 as shown in FIG. The actual valve timing temporarily advances. It may vary in the direction.

  As shown in FIGS. 8D and 10D, during the retard operation of the VCT 11, the control mode of the VVL 46 is switched from the high lift mode to the low lift mode, and the hydraulic pressure supplied to the VCT 11 increases. In this case, the actual valve timing hardly fluctuates.

  Therefore, the ECU 43 executes a valve timing fluctuation prevention control routine of FIG. 12 to be described later, so that the check valves 30 and 31 are in a state to prevent fluctuation of the actual valve timing in accordance with the switching direction of the control mode of the VVL 46. The valve timing fluctuation prevention control for controlling (that is, the open / close state of the drain switching valves 34, 35) is executed as follows.

  When the VVL 46 is switched from the low lift mode to the high lift mode (when the hydraulic pressure supplied to the VCT 11 decreases), the target valve timing of the VCT 11 is limited by the retard side guard value and the OCV current value is retarded by the retard side guard. By limiting the VCT 11 to a state in which the retard operation is hardly performed by limiting the value, the control region of the VCT 11 is restricted to the region where the drain switching valve 34 on the advance chamber 18 side is closed, and the check on the advance chamber 18 side is checked. The valve 30 is controlled to function. Accordingly, the hydraulic pressure in the advance chamber 18 is temporarily prevented from suddenly decreasing by the check valve 30 on the advance chamber 18 side, and the actual valve timing is prevented from temporarily changing in the retard direction. .

  On the other hand, when the VVL 46 is switched from the high lift mode to the low lift mode (when the hydraulic pressure supplied to the VCT 11 increases), the target valve timing of the VCT 11 is limited by the advance side guard value and the OCV current value is advanced. By restricting by the side guard value and making the VCT 11 hardly advance, the control region of the VCT 11 is limited to the region in which the drain switching valve 35 on the retard chamber 19 side is closed and the retard chamber 19 side is closed. The check valve 31 is controlled to function. Thus, the check valve 31 on the retard chamber 19 side prevents the hydraulic pressure in the retard chamber 19 from temporarily decreasing due to the hydraulic pressure increase in the advance chamber 18, and the actual valve timing is temporarily advanced. Prevents fluctuations in direction.

  The processing contents of the VCT control routine of FIG. 11 and the valve timing fluctuation prevention control routine of FIG. 12 executed by the ECU 43 will be described below.

[VCT control routine]
The VCT control routine of FIG. 11 is executed at a predetermined cycle (for example, a cycle of 5 ms) during engine operation, and serves as a control means in the claims. When this routine is started, first, in step 101, operating conditions (for example, engine speed, load, cooling water temperature, etc.) are detected, and in the next step 102, VCT control execution conditions are established based on the detected operating conditions. It is determined whether or not. As a result, if it is determined that the VCT control execution condition is not satisfied, this routine is terminated without performing the subsequent processing. When the VCT control is not executed, the target valve timing VVT is maintained at 0 (most retarded position).

  On the other hand, if it is determined in step 102 that the VCT control execution condition is satisfied, the process proceeds to step 103, where the output signal of the crank angle sensor 44 and the cam angle sensor 45 that is generated subsequently are output. After calculating the actual valve timing VTA (advance amount from the most retarded position to the current position) based on the phase difference with the output signal, in the next step 104, the current operating conditions (engine speed, load, etc.) Accordingly, the target valve timing VTT is calculated from a map or the like.

  Thereafter, the routine proceeds to step 105, where an OCV target current calculation routine (not shown) is executed, and the OCV target current iVVT is calculated by PD control or the like according to the deviation between the target valve timing VTT and the actual valve timing VTA. In the next step 106, the control duty for controlling the control current of the hydraulic control valve 21 (OCV) to the OCV target current iVVT is calculated, and this routine is finished.

[Valve timing fluctuation prevention control routine]
The valve timing fluctuation prevention control routine of FIG. 12 is executed at a predetermined cycle (for example, 5 ms cycle) during engine operation, and serves as valve timing fluctuation prevention control means in the claims. When this routine is started, first, at step 201, the current target control mode of the VVL 46 is read, and then the routine proceeds to step 202, where the target control mode of the VVL 46 is switched from the low lift mode to the high lift mode. Determine.

  If it is determined in step 202 that the target control mode of the VVL 46 has been switched from the low lift mode to the high lift mode, the valve timing fluctuation prevention control is executed as follows.

  First, in step 203, the target valve timing VTT at the time when the target control mode of the VVL 46 is switched from the low lift mode to the high lift mode is set as the retard side guard value of the target valve timing VTT, and then the process proceeds to step 204. The target valve timing VTT is guarded with the retard side guard value to limit the target valve timing VTT so as not to exceed the retard side guard value.

  Thereafter, the process proceeds to step 205, in which it is determined whether or not the current OCV current value (for example, the OCV target current iVVT) is equal to or less than a predetermined value on the retard side. This retarded side predetermined value is an OCV current value corresponding to a sudden response point (see FIG. 4) on the retarded side of the VCT 11 (an OCV current value at which the opening / closing of the drain switching valve 34 in the advance chamber 18 is switched). ) Is set.

  If it is determined in step 205 that the OCV current value is larger than the retard side predetermined value, the process proceeds to step 208 without executing the processes in steps 206 and 207. On the other hand, if it is determined in step 205 that the OCV current value is equal to or smaller than the retard side predetermined value, the process proceeds to step 206, and the retard side predetermined value or a value slightly larger than that is set to the delay of the OCV current value. After setting as the corner-side guard value, the process proceeds to step 207, where the OCV current value is guarded with the retard-side guard value, and the OCV current value is limited to the retard-side guard value or more.

  In this way, the target valve timing VTT of the VCT 11 is limited by the retard side guard value, and the OCV current value is limited by the retard side guard value so that the VCT 11 does not substantially retard, thereby controlling the VCT 11. The region is limited to a region where the drain switching valve 34 on the advance chamber 18 side is closed, and the check valve 30 on the advance chamber 18 side is controlled to function.

  Thereafter, the process proceeds to step 208, where it is determined whether or not the switching of the control mode is completed depending on whether or not the VVL 46 has actually switched from the low lift mode to the high lift mode. Repeat the process of ~ 207. Thereafter, when it is determined in step 208 that the switching of the control mode of the VVL 46 has been completed, the process proceeds to step 216, the guard for the target valve timing VTT and the OCV current value is released, and the valve timing fluctuation prevention control is terminated. .

  On the other hand, if it is determined in step 202 that the target control mode of the VVL 46 is not switched from the low lift mode to the high lift mode, the process proceeds to step 209 and the target control mode of the VVL 46 is changed from the high lift mode to the low lift mode. It is determined whether or not the mode has been switched.

  If it is determined in step 209 that the target control mode of the VVL 46 has been switched from the high lift mode to the low lift mode, the valve timing fluctuation prevention control is executed as follows.

  First, in step 210, the target valve timing VTT at the time when the target control mode of the VVL 46 is switched from the high lift mode to the low lift mode is set as the advance side guard value of the target valve timing VTT, and then the process proceeds to step 211. The target valve timing VTT is guarded with the advance side guard value to limit the target valve timing VTT so as not to exceed the advance side guard value.

  Thereafter, the process proceeds to step 212, and it is determined whether or not the current OCV current value (for example, the OCV target current iVVT) is equal to or greater than a predetermined value on the advance side. This advance side predetermined value is the OCV current value corresponding to the sudden response point (see FIG. 4) of the advance side of the VCT 11 (the OCV current value at which the opening / closing of the drain switching valve 35 of the retard chamber 19 is switched). ) Is set.

  If it is determined in step 212 that the OCV current value is smaller than the advance side predetermined value, the process proceeds to step 215 without executing the processes in steps 213 and 214. On the other hand, if it is determined in step 212 that the OCV current value is greater than or equal to the advance side predetermined value, the process proceeds to step 213, and the advance side predetermined value or a value slightly smaller than that is advanced to the OCV current value. After setting as the corner-side guard value, the process proceeds to step 214, where the OCV current value is guarded with the advance-side guard value, and the OCV current value is limited to the advance-side guard value or less.

  In this way, the target valve timing VTT of the VCT 11 is limited by the advance side guard value, and the OCV current value is limited by the advance side guard value so that the VCT 11 is hardly advanced, thereby controlling the VCT 11. The region is limited to a region where the drain switching valve 35 on the retarding chamber 19 side is closed, and the check valve 31 on the retarding chamber 19 side is controlled to function.

  Thereafter, the process proceeds to step 215, where it is determined whether or not the switching of the control mode is completed depending on whether or not the VVL 46 has actually switched from the high lift mode to the low lift mode. Repeat the process of ~ 214. Thereafter, when it is determined in step 215 that the switching of the control mode of the VVL 46 has been completed, the process proceeds to step 216, the guard for the target valve timing VTT and the OCV current value is released, and the valve timing fluctuation prevention control is terminated. .

  In the present embodiment described above, as shown in the time chart of FIG. 13, when the control mode of the VVL 46 is switched from the low lift mode to the high lift mode (when the hydraulic pressure supplied to the VCT 11 decreases), The target valve timing is limited by the retard side guard value and the OCV current value is limited by the retard side guard value so that the VCT 11 is hardly retarded so that the control region of the VCT 11 is set to the advance chamber 18 side. The drain switching valve 34 is limited to a region where the drain switching valve 34 is closed, and the check valve 30 on the advance chamber 18 side is controlled to function. As a result, even if the hydraulic pressure supplied to the VCT 11 is lowered when the control mode of the VVL 46 is switched from the low lift mode to the high lift mode, the advance chamber 18 is temporarily lowered. The check valve 30 on the side prevents the actual valve timing from temporarily changing in the retarding direction, and realizes stable valve timing control regardless of the operating state of the VVL 46. be able to.

  On the other hand, when the control mode of the VVL 46 is switched from the high lift mode to the low lift mode (when the hydraulic pressure supplied to the VCT 11 increases), the target valve timing of the VCT 11 is limited by the advance side guard value and the OCV current value By limiting the VCT 11 with the advance side guard value so that the VCT 11 does not substantially advance, the control region of the VCT 11 is limited to the region where the drain switching valve 35 on the retard chamber 19 side is closed, and the retard chamber is Control is performed so that the check valve 31 on the 19th side functions. As a result, even if the hydraulic pressure supplied to the VCT 11 rises when the control mode of the VVL 46 is switched from the high lift mode to the low lift mode, the hydraulic pressure in the retard chamber 19 suddenly suddenly increases due to the rise in the hydraulic pressure in the advance chamber 18. The check valve 31 on the retarded angle chamber 19 side can be prevented from lowering, and the actual valve timing can be prevented from temporarily changing in the advance angle direction, without being influenced by the operating state of the VVL 46. Stable valve timing control can be realized.

  By the way, in the valve timing fluctuation prevention control, if only the target valve timing is limited by the guard value, if the deviation between the target valve timing after the limitation and the actual valve timing is relatively large, the deviation is sufficient. There is a possibility that the advance operation or retard operation of the VCT 11 is continued until it becomes smaller, and the state of the check valves 30, 31 cannot be quickly switched.

  In this respect, in the present embodiment, the OCV current value corresponding to the deviation between the target valve timing and the actual valve timing is limited by the guard value during the valve timing fluctuation prevention control. Even when the deviation from the timing is relatively large, the state of the check valves 30 and 31 can be quickly switched.

  However, according to the present invention, only one of the target valve timing and the OCV current value may be limited by the guard value in the valve timing fluctuation prevention control. Further, the control input of the VCT 11 other than the OCV current value (for example, the control duty of the hydraulic control valve 21) may be limited by a guard value.

  Further, in the present embodiment, the drain switching valves 34 and 35 of each hydraulic chamber are configured to be driven by hydraulic pressure and are provided inside the housing 12 of the VCT 11, and the hydraulic pressure for driving the drain switching valves 34 and 35 is set. Since the hydraulic switching valve 38 for switching is provided outside the housing 12 of the VCT 11, the drain switching valves 34 and 35 can be reduced in size, and electrical wiring to the drain switching valves 34 and 35 is not required. The switching valves 34 and 35 can be compactly assembled together with the check valves 30 and 31 in a narrow space inside the VCT 11 to increase the degree of freedom of design, and the drain switching valves 34 and 35 near each hydraulic chamber. The drain oil passages 32 and 33 can be opened / closed with good response near the hydraulic chamber during advance / retard operation.

In addition, in this embodiment, since the hydraulic pressure switching valve 38 is integrated with the hydraulic control valve 21, it is possible to satisfy the demands for reducing the number of parts, reducing the cost, and reducing the size.
However, in the present invention, the hydraulic pressure switching valve 38 may be provided separately from the hydraulic control valve 21.

  In the above embodiment, the present invention is applied to a system in which oil pressure is supplied by the oil pump 27 common to both the VCT 11 and the VVL 46. However, the present invention is applied to a system in which the hydraulic circuit of the VCT 11 and the hydraulic circuit of the VVL 46 are separated. You may do it. Even in the case of a system in which the hydraulic circuit of the VCT 11 and the hydraulic circuit of the VVL 46 are separated, when the torque of the camshaft fluctuates due to switching of the control mode of the VVL 46, the hydraulic pressure on the side where the check valve of the VCT 11 does not function due to the influence. There is a possibility that the hydraulic valve is pushed out from the chamber and the actual valve timing may fluctuate. However, the fluctuation of the actual valve timing can be prevented by executing the valve timing fluctuation prevention control of the present invention.

  In the above embodiment, the valve timing fluctuation prevention control is executed based on the operating state of the VVL 46 that switches between two control modes. However, the VVL and valve lift that switch between three or more control modes. The valve timing fluctuation prevention control may be executed based on the operating state of the VVL that continuously changes the amount. Alternatively, valve timing fluctuation prevention control may be executed based on the operating state of the electrically driven VVL. Further, the valve timing fluctuation prevention control may be executed based on the operating state of a hydraulic pressure / camshaft torque fluctuation element (for example, a power steering device or the like) other than VVL.

  In the present invention, valve timing variation prevention control may be permitted when the deviation between the target displacement angle and the actual displacement angle of the VCT 11 is equal to or greater than a predetermined value. That is, when the deviation between the target displacement angle and the actual displacement angle of the VCT 11 exceeds a predetermined value and the VCT 11 is advanced or retarded, the retard chamber side or advance chamber side check valves 30 and 31 are operated. In order to prevent the valve from functioning, it is determined that the actual valve timing may vary due to the influence of the operating state of the hydraulic pressure / camshaft torque variation element, and the valve timing variation prevention control is permitted. By doing so, when the check valve 30, 31 on the retard chamber side or the advance chamber side is made non-functional (that is, the actual valve timing varies due to the influence of the operating state of the hydraulic pressure / cam shaft torque variation element). The valve timing fluctuation prevention control can be executed only when there is a possibility.

  The present invention is not limited to the configuration of the variable valve timing adjusting mechanism 11 shown in FIG. 1, and may be applied to, for example, the variable valve timing adjusting mechanisms 71 and 72 of other embodiments shown in FIG. 14 or FIG. it can.

  The variable valve timing adjusting mechanism 71 shown in FIG. 14 is different from the variable valve timing adjusting mechanism 11 shown in FIG. In FIG. 14, 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. 14, the advance / retard hydraulic control. Solenoids 36 and 51 are respectively provided in the first hydraulic control valve 37 that realizes the function and the second hydraulic control valve 38 that realizes the drain switching control function, and the solenoids 36 and 51 are independently provided by separate ECUs 43 and 52. It is set as the structure controlled. One ECU 43 (first control means) controls the current of the first hydraulic control valve 37 in accordance with the deviation between the VCT actual displacement angle and the target displacement angle, and the other ECU 52 (second control means) The hydraulic pressure that drives the drain switching valves (drain control valves) 34 and 35 is controlled by controlling the current of the second hydraulic control valve 38.

  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. 14, a so-called normally closed type (normally closed type) switching valve that is held in a closed position by 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. 14, 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. Although the switching valves 34 and 35 are provided, in FIG. 14, a hydraulic pressure supply passage 28 for the advance chamber 18 of one vane storage chamber 16 and a 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, when the variable valve timing adjusting mechanism 71 is advanced, the drain switching valve on the advance chamber side through which hydraulic oil flows is closed and the drain switching valve on the retard chamber side from which hydraulic oil is discharged is opened. When the second hydraulic control valve 38 is controlled and the variable valve timing adjusting mechanism 71 is retarded, the drain switching valve on the retard chamber side into which the hydraulic oil flows is closed and the hydraulic oil is discharged. The second hydraulic control valve 38 is controlled so as to open the drain switching valve on the corner chamber side. In short, during the advance / retard operation, either one of the advance chamber 18 side or the retard chamber 19 side drain switching valve 34 or 35 is opened according to the displacement direction, and either one of the check valves is opened. By controlling the second hydraulic control valve 38 so that 30 or 31 does not function, and by controlling the control current of the first hydraulic control valve 37 to vary the hydraulic pressure supplied to the variable 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. 14 configured as described above.
Next, the configuration of the variable valve timing adjusting mechanism 72 in FIG. 15 will be described focusing on the differences from FIG. Also in FIG. 15, 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. 15, 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 control valve 60 and the check valves 30 and 31 and connected to drain switching valves (drain control 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. 15 configured as described above.

It is a figure which shows roughly the variable valve timing adjustment mechanism and its hydraulic control circuit in one Example of this invention. It is a figure for demonstrating retardation operation | movement, holding | maintenance operation | movement, and advance operation 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 figure which shows schematic structure of a variable valve lift mechanism. The behavior during the holding operation of the variable valve timing adjustment mechanism without the check valve is shown. (A) is a time chart when the variable valve lift mechanism is switched from the low lift mode to the high lift mode, and (b) is variable. It is a time chart when the valve lift mechanism is switched from the high lift mode to the low lift mode. The behavior during the holding operation of the variable valve timing adjustment mechanism with a check valve is shown. (A) is a time chart when the variable valve lift mechanism is switched from the low lift mode to the high lift mode, and (b) is variable. It is a time chart when the valve lift mechanism is switched from the high lift mode to the low lift mode. It is a figure for demonstrating the behavior when the control mode of a variable valve lift mechanism is switched at the time of an advance operation and a retard operation of a variable valve timing adjustment mechanism with a check valve. (A) is a time chart showing the behavior when the variable valve lift mechanism is switched from the low lift mode to the high lift mode during the advance operation of the variable valve timing adjustment mechanism with a check valve, and (b) is a check. It is a time chart which shows the behavior when the variable valve lift mechanism is switched from the low lift mode to the high lift mode during the retarding operation of the variable valve timing adjusting mechanism with a valve. (C) is a time chart showing the behavior when the variable valve lift mechanism is switched from the high lift mode to the low lift mode during the advance operation of the variable valve timing adjustment mechanism with a check valve. (D) is a check. It is a time chart which shows the behavior when the variable valve lift mechanism is switched from the high lift mode to the low lift mode during the retarding operation of the variable valve timing adjusting mechanism with a valve. It is a flowchart explaining the flow of a process of a VCT control routine. It is a flowchart explaining the flow of a process of a valve timing fluctuation | variation prevention control routine. It is a time chart explaining an example of valve timing variation prevention control. It is a figure which shows schematically the variable valve timing adjustment mechanism in the other Example (the 1) of this invention, and its hydraulic control circuit. It is a figure which shows schematically the variable valve timing adjustment mechanism in the other Example (the 2) of this invention, and its hydraulic control circuit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Variable valve timing adjustment mechanism (VCT), 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 (drain control valve), 37 ... Advance / Delay angle hydraulic control function (first hydraulic control valve), 38 ... Drain switching control function (hydraulic switching valve, second hydraulic control valve), 43 ... ECU (control means, valve timing fluctuation prevention control means, first Control means), 44 ... crank angle sensor, 45 ... cam angle sensor, 46 ... variable valve lift mechanism, 52 ... ECU (second control means), 60 ... hydraulic control valve, 71, 72 ... variable valve timing adjuster

Claims (31)

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 divided into an advance chamber and a retard chamber by the vanes, respectively, and at least one vane storage Each of the hydraulic chambers in the hydraulic supply oil passage of the advance chamber and the retarder chamber of the chamber (“hydraulic chamber” means either “advance chamber” or “retard chamber”) In addition to providing a check valve that prevents backflow of hydraulic oil from the oil supply, a drain oil passage that bypasses the check valve is provided in parallel in each hydraulic chamber oil supply oil passage, and each drain oil passage is switched to a drain. In a control device of a vane type variable valve timing adjustment mechanism provided with a valve,
The hydraulic control valve is controlled so as to make the actual displacement angle of the VCT coincide with the target displacement angle to vary the hydraulic pressure of each hydraulic chamber, and the opening and closing of the drain switching valve of each hydraulic chamber is controlled to check each hydraulic chamber. Control means for switching between a functioning state and a non-functioning state of the valve;
Fluctuation in the actual displacement angle of the VCT is prevented based on the operating state of the hydraulic pressure supplied to the VCT and / or the element that varies the camshaft torque of the internal combustion engine (hereinafter referred to as “hydraulic pressure / camshaft torque fluctuation element”). And a valve timing fluctuation prevention control means for executing valve timing fluctuation prevention control for controlling the state of the drain switching valve and the check valve in each hydraulic chamber as described above. Control device for the mechanism.   2. The vane type according to claim 1, wherein the hydraulic pressure / camshaft torque variation element is a hydraulically driven variable valve lift mechanism that changes a valve lift amount of an intake valve and / or an exhaust valve of an internal combustion engine. Control device for variable valve timing adjustment mechanism.   When the VCT is advanced, the control means closes the advance chamber side drain switching valve for allowing the hydraulic oil to flow in to function the advance chamber side check valve and discharges the hydraulic oil. When the retard valve is controlled so that the retard valve on the retard chamber side is not opened and the check valve on the retard chamber is not functioned, and the VCT is retarded, the drain switch valve on the retard chamber side into which hydraulic oil flows is supplied. To control the retard chamber side check valve so that it does not function by opening the advance chamber side drain switching valve from which hydraulic oil is discharged. The control device for a vane type variable valve timing adjusting mechanism according to claim 1 or 2.   In the holding operation for holding the actual displacement angle of the VCT at the target displacement angle, the control means closes both the advance angle chamber side and the retard angle chamber side drain switching valves and opens the advance angle chamber side. 4. The control device for a vane type variable valve timing adjusting mechanism according to claim 3, wherein the control is performed so that both the check valves on the retard chamber side function.   The valve timing fluctuation prevention control means executes the valve timing fluctuation prevention control by limiting a target displacement angle of the VCT based on an operating state of the hydraulic pressure / camshaft torque fluctuation element. 5. A control device for a vane type variable valve timing adjusting mechanism according to 3 or 4.   4. The valve timing fluctuation prevention control means executes the valve timing fluctuation prevention control by limiting a control input of the VCT based on an operating state of the hydraulic pressure / camshaft torque fluctuation element. Or a control device for a vane-type variable valve timing adjusting mechanism according to 4;   The valve timing fluctuation prevention control means performs the valve timing fluctuation prevention control by limiting a target displacement angle of the VCT and limiting a control input of the VCT based on an operation state of the hydraulic pressure / camshaft torque fluctuation element. 5. The control device for a vane type variable valve timing adjusting mechanism according to claim 3, wherein the control device is executed.   8. The valve timing fluctuation prevention control unit permits the valve timing fluctuation prevention control when a deviation between a target displacement angle and an actual displacement angle of the VCT is a predetermined value or more. A control device for a vane type variable valve timing adjusting mechanism according to claim 1. Each drain switching valve is configured to be hydraulically driven and provided in the housing of the VCT,
The vane type variable valve timing adjusting mechanism according to any one of claims 1 to 8, wherein a hydraulic pressure switching valve for switching a hydraulic pressure for driving each drain switching valve is provided outside the housing of the VCT. Control device.   10. The control device for a vane type variable valve timing adjustment mechanism according to claim 9, 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 that is provided in a hydraulic pressure supply oil passage of the advance chamber in the vane storage chamber and prevents the backflow of hydraulic oil from the advance chamber, and a first that bypasses the first check valve. A first drain control valve that is provided in the drain oil passage and is driven by hydraulic pressure, and provided in a hydraulic supply oil passage in the retard chamber of at least one vane storage chamber, and reverses the backflow of hydraulic oil from the retard chamber. A second check valve for preventing, a second drain control valve provided in a second drain oil passage that bypasses the second check valve and driven by hydraulic pressure,
A first hydraulic control valve that controls the hydraulic pressure supplied to the VCT;
A second hydraulic control valve for controlling a hydraulic pressure for driving the first drain control valve and the second drain hydraulic valve;
In a control device for a vane type variable valve timing adjustment mechanism comprising a control means for controlling the first hydraulic control valve and the second hydraulic control valve,
The control means controls the actual displacement angle of the VCT based on the operating state of the hydraulic pressure supplied to the VCT and / or the element that varies the torque of the camshaft of the internal combustion engine (hereinafter referred to as “hydraulic / camshaft torque fluctuation element”). A control device for a vane-type variable valve timing adjustment mechanism, comprising valve timing fluctuation prevention control means for executing valve timing fluctuation prevention control for controlling each drain control valve so as to prevent fluctuations in the valve timing.   12. The vane type according to claim 11, wherein the hydraulic pressure / camshaft torque fluctuation element is a hydraulically driven variable valve lift mechanism that changes a valve lift amount of an intake valve and / or an exhaust valve of an internal combustion engine. Control device for variable valve timing adjustment mechanism.   When the VCT is advanced, the control means closes the advance chamber side drain control valve for allowing the hydraulic oil to flow in to function the advance chamber side check valve and discharges the hydraulic oil. When the retard control chamber side check valve is controlled not to function by opening the retard chamber side drain control valve and the VCT is retarded, the retard chamber side drain control valve that allows hydraulic oil to flow in is operated. To control the retarding chamber side check valve so that the advancement chamber side drain control valve from which hydraulic oil is discharged is opened and the advancement chamber side check valve does not function. 13. The control device for a vane type variable valve timing adjusting mechanism according to claim 11 or 12.   The control means closes the first drain control valve and the second drain control valve and closes the first check valve when holding the actual displacement angle of the VCT at a target displacement angle. 14. The control device for a vane type variable valve timing adjusting mechanism according to claim 13, wherein the control is performed so that the first check valve and the second check valve function.   The valve timing fluctuation prevention control means executes the valve timing fluctuation prevention control by limiting a target displacement angle of the VCT based on an operating state of the hydraulic pressure / camshaft torque fluctuation element. 15. A control device for a vane type variable valve timing adjusting mechanism according to 13 or 14.   The valve timing fluctuation prevention control means executes the valve timing fluctuation prevention control by limiting a control input of the VCT based on an operation state of the hydraulic pressure / camshaft torque fluctuation element. Or a control device for a vane-type variable valve timing adjustment mechanism according to 14,   The valve timing fluctuation prevention control means performs the valve timing fluctuation prevention control by limiting a target displacement angle of the VCT and limiting a control input of the VCT based on an operation state of the hydraulic pressure / camshaft torque fluctuation element. 15. The control device for a vane type variable valve timing adjusting mechanism according to claim 13, wherein the control device is executed.   18. The valve timing fluctuation prevention control unit permits the valve timing fluctuation prevention control when a deviation between a target displacement angle and an actual displacement angle of the VCT is a predetermined value or more. A control device for a vane type variable valve timing adjusting mechanism according to claim 1. Each drain control valve is configured to be hydraulically driven and provided in the housing of the VCT,
The variable vane type according to any one of claims 11 to 18, wherein a second hydraulic control valve for controlling a hydraulic pressure for driving each drain control valve is provided outside the housing of the VCT. Control device for valve timing adjustment mechanism. The first hydraulic control valve and the second hydraulic control valve are controllable independently,
The control means controls the second hydraulic control valve to open and close each drain control valve, and the second hydraulic control valve to control the actual displacement angle of the VCT. 20. The control device for a vane type variable valve timing adjusting mechanism according to claim 11, further comprising: a first control unit that controls the target displacement angle. The first hydraulic control valve and the second hydraulic control valve are integrated with a drive shaft,
The control means controls the second hydraulic control valve to open and close each drain control valve, and controls the first hydraulic control valve so that the actual displacement angle of the VCT becomes the target displacement angle. 20. The control device for a vane type variable valve timing adjustment mechanism according to claim 11, further comprising a third control means for controlling the control of the variable valve timing adjustment mechanism. 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 divided into an advance chamber and a retard chamber by the vanes, respectively, and at least one vane storage A first check valve that prevents backflow of hydraulic oil from the advance chamber and a first drain oil passage that bypasses the first check valve are provided in the hydraulic supply oil passage of the advance chamber. A second check valve for preventing a backflow of hydraulic oil from the retard chamber, and a second check valve in a hydraulic pressure oil passage of the retard chamber of the at least one vane storage chamber. Providing a second drain oil passage to bypass;
A vane variable valve timing in which a hydraulic control valve for controlling the hydraulic pressure supplied to the VCT is integrated with a drain oil passage control function for opening / closing the first drain oil passage and the second drain oil passage. A control device for the adjusting mechanism,
The control means controls the actual displacement angle of the VCT based on the operating state of the hydraulic pressure supplied to the VCT and / or the element that varies the torque of the camshaft of the internal combustion engine (hereinafter referred to as “hydraulic / camshaft torque fluctuation element”). Valve timing fluctuation prevention control means for executing valve timing fluctuation prevention control for controlling each drain oil passage so as to prevent fluctuations in
A control device for a vane-type variable valve timing adjusting mechanism.   23. The vane type according to claim 22, wherein the hydraulic pressure / camshaft torque variation element is a hydraulically driven variable valve lift mechanism that changes a valve lift amount of an intake valve and / or an exhaust valve of an internal combustion engine. Control device for variable valve timing adjustment mechanism.   When the VCT is advanced, the control means functions as a check valve on the advance chamber side that closes the drain oil passage on the advance chamber side that allows the hydraulic oil to flow in and allows the hydraulic oil to flow in. In the case of controlling the delay valve side drain valve from which the oil is discharged to function the check valve on the retard chamber side from which the working oil is discharged and operating the VCT at a retarded angle, Actuate the check valve on the retarded angle chamber side that closes the drain oil passage on the retarded angle chamber side where the hydraulic oil flows in and opens the drain oil path on the advanced angle chamber side where the hydraulic fluid is discharged. 24. The control device for a vane type variable valve timing adjusting mechanism according to claim 22 or 23, wherein control is performed so that the check valve on the advance angle chamber side from which oil is discharged does not function.   The control means closes the first drain oil passage and the second drain oil passage and closes the first check valve when holding the actual displacement angle of the VCT at a target displacement angle. 25. The control device for a vane type variable valve timing adjusting mechanism according to claim 24, wherein the control is performed so that the first check valve and the second check valve function. 26. The fluctuation prevention control means executes the valve timing fluctuation prevention control by limiting a target displacement angle of the VCT based on an operating state of the hydraulic pressure / camshaft torque fluctuation element. The control device of the vane type variable valve timing adjustment mechanism described in 1.   26. The valve timing fluctuation prevention control means executes the valve timing fluctuation prevention control by limiting a control input of the VCT based on an operating state of the hydraulic pressure / camshaft torque fluctuation element. Or a control device of a vane type variable valve timing adjusting mechanism according to 26.   The valve timing fluctuation prevention control means performs the valve timing fluctuation prevention control by limiting a target displacement angle of the VCT and limiting a control input of the VCT based on an operating state of the hydraulic pressure / camshaft torque fluctuation element. 28. The control device for a vane type variable valve timing adjustment mechanism according to claim 26, wherein the control device is executed.   29. The valve timing fluctuation prevention control unit permits the valve timing fluctuation prevention control when a deviation between a target displacement angle and an actual displacement angle of the VCT is a predetermined value or more. A control device for a vane type variable valve timing adjusting mechanism according to claim 1. A first drain control valve that is hydraulically driven in the first drain oil passage; and a second drain control valve that is hydraulically driven in the second drain oil passage;
The first drain oil passage is opened / closed by opening / closing the first drain control valve by hydraulic control by the drain oil passage control function of the hydraulic control valve, and the second drain is opened. 30. The control device for a vane type variable valve timing adjustment mechanism according to claim 23, wherein the second drain oil passage is opened / closed by opening / closing a control valve. . Each drain control valve is provided inside the housing of the VCT,
31. The control device for a vane type variable valve timing adjusting mechanism according to claim 30, wherein the hydraulic control valve for switching the hydraulic pressure for driving each drain control valve is provided outside the housing of the VCT.

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