JP5067720B2 - Variable valve timing control device for internal combustion engine - Google Patents

Description

  The present invention provides a variable internal combustion engine that includes an intermediate lock mechanism that locks the rotational phase of a camshaft relative to the crankshaft of the internal combustion engine (hereinafter referred to as “VCT phase”) with an intermediate lock phase that is positioned approximately in the middle of the adjustable range. The invention relates to a valve timing control device.

  Conventionally, in a hydraulically driven variable valve timing device, as described in Patent Document 1 (Japanese Patent Laid-Open No. 9-324613) and Patent Document 2 (Japanese Patent Laid-Open No. 2001-159330), the engine is stopped. The lock phase is set approximately in the middle of the adjustable range of the VCT phase to expand the adjustable range of the valve timing (VCT phase). In this system, the intermediate lock phase that locks when the engine is stopped is set to a phase suitable for starting, the engine is started with this intermediate lock phase, the lock is released after the start is completed, and the VCT phase is set according to the engine operating state. The target VCT phase is controlled. In a variable valve timing device for an intake valve, for example, the intake valve timing is controlled on the retard side when the load is low such as during steady running, and the intake valve timing is controlled on the advance side when the load is high such as when accelerating. I have to.

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

  By the way, in the variable valve timing device provided with the intermediate lock mechanism, it is necessary to assume that an abnormal situation occurs in which the lock pin does not normally lock when a lock request is generated. For example, even if an abnormal situation occurs in which the lock pin does not normally lock, normal variable valve timing control performed in the unlocked state is not hindered, so that it is difficult to determine the abnormality.

  Since the engine is started on the premise that the VCT phase is locked with the intermediate lock phase, the startability deteriorates if an abnormal situation occurs in which the lock pin does not normally lock in response to the lock request. Or the idling stability after starting deteriorates. Therefore, when an abnormal situation occurs in which the lock pin does not normally lock in response to the lock request, it is necessary to provide a function for detecting the abnormal situation immediately.

  Therefore, the problem to be solved by the present invention is to develop a technique capable of confirming the protruding state of the lock pin subjected to lock control.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a hydraulically driven variable valve that adjusts the valve timing by changing the rotational phase of the camshaft (hereinafter referred to as “VCT phase”) with respect to the crankshaft of the internal combustion engine. A variable internal combustion engine comprising: a timing device; a lock pin that locks the VCT phase with an intermediate lock phase positioned within the adjustable range; and a hydraulic control device that controls the hydraulic pressure that drives the variable valve timing device and the lock pin. In the valve timing control device, a control characteristic variable means for making a VCT phase control characteristic when the lock pin protrudes a predetermined amount or more and a VCT phase control characteristic when the lock pin does not protrude, and a lock request Execute lock control to control the hydraulic control device so that the lock pin protrudes when it occurs And a lock control means for continuing a lock mode for holding the lock state until the lock request is released, and a lock pin protrusion state for determining the protrusion state of the lock pin based on the behavior of the VCT phase during the lock mode. And determining means. The intermediate lock phase may be positioned within the adjustable range, for example, may be positioned in the middle of the adjustable range, or may be provided on the advance side and the retard side with respect to the intermediate position. good.

  In this case, the VCT phase control characteristic when the lock pin protrudes by a predetermined amount or more and the VCT phase control characteristic when the lock pin does not protrude differ from each other. VCT phase control characteristics differ depending on whether or not the protrusion exceeds a predetermined amount, and the behavior of the VCT phase varies. Accordingly, it is possible to determine whether or not the lock pin protrudes a predetermined amount or more based on the behavior of the VCT phase during the lock mode, and it is possible to check the protrusion state of the lock pin during the lock mode.

  Specifically, as in claim 2, the control characteristic varying means includes a hydraulic chamber (advance chamber or retard chamber) to which hydraulic oil for driving the VCT phase to the advance side or retard side is supplied. ), And when the lock pin protrudes a predetermined amount or more, the hydraulic chamber communicates with the outside via the communication means, so that the lock pin is locked into the lock hole during the lock mode. What is necessary is just to comprise so that the fluctuation | variation of the VCT phase by the torque of a cam shaft when the lock pin protrudes more than the predetermined amount when it is not fitted becomes larger than when the lock pin does not protrude. With this configuration, when the lock pin does not fit into the lock hole during the lock mode, the cause is the mismatch between the phases of the lock pin and the lock hole, or the lock pin does not protrude (retracted). ) Can be determined based on whether the variation in the VCT phase is large or small.

  In this case, if the state in which the fluctuation of the VCT phase is equal to or smaller than the first determination value continues during the lock mode as in claim 3, it is determined that the lock pin is in the locked state in which the lock pin is fitted in the lock hole. In addition, when the state in which the variation of the VCT phase is greater than or equal to the second determination value greater than the first determination value continues during the lock mode, the lock pin only fits the predetermined amount and the lock pin fits into the lock hole. It is determined that it is not jammed (the phase mismatch between the lock pin and the lock hole), and the state in which the variation of the VCT phase is within the range between the first determination value and the second determination value during the lock mode continues. In such a case, it may be determined that the lock pin protrudes poorly. In this way, based on the change in the VCT phase during the lock mode, the locked state, the lock failure (the phase mismatch between the lock pin and the lock hole), and the lock pin protrusion failure (retracted) can be easily performed. Can be determined.

  Further, as in claim 4, the first determination value and the second determination value may be set based on at least one of oil temperature, cooling water temperature, and internal combustion engine rotation speed. The viscosity (flow resistance) of the hydraulic oil changes according to the oil temperature and the cooling water temperature, and the hydraulic pressure supplied to the hydraulic chamber of the variable valve timing device changes. Therefore, the fluctuation range of the VCT phase varies depending on the oil temperature and the cooling water temperature. Change. In addition, since the hydraulic pressure is changed by changing the rotational speed (discharge amount) of the oil pump that pumps hydraulic oil according to the rotational speed of the internal combustion engine, the fluctuation range of the VCT phase is changed according to the rotational speed of the internal combustion engine. Therefore, if the first determination value and the second determination value are set based on at least one of oil temperature, cooling water temperature, and internal combustion engine rotation speed, the first determination value and the second determination value are It can be set to an appropriate value according to the viscosity of the hydraulic oil and the rotational speed (discharge amount) of the oil pump.

  Further, as in claim 5, it is determined whether or not the VCT phase is an intermediate lock phase during the lock mode, and based on the determination result and the lock pin protrusion condition determined by the lock pin protrusion condition determining means. Thus, it is preferable to discriminate between lock success and lock failure, and re-execute lock control by the lock control means when it is determined that lock has failed. In this way, if a lock failure occurs due to a phase mismatch between the lock pin and the lock hole, lock control is re-executed to match the phase between the lock pin and the lock hole, thereby locking the lock pin. It is possible to succeed. At this time, the number of re-execution of the lock control may be only once, or the re-execution of the lock control may be repeated within a range not exceeding a preset maximum number until the lock pin is successfully locked.

  Further, as in claim 6, when it is determined that the lock pin is not fitted in the lock hole during the lock mode, can the hydraulic pressure be maintained so that the VCT phase can be maintained during idling based on the state of the internal combustion engine? If it is determined whether or not a hydraulic pressure capable of maintaining the VCT phase cannot be secured during idling, the VCT phase may be controlled to the most retarded phase or the most advanced angle phase. In short, if it is determined that the hydraulic pressure that can maintain the VCT phase during idling cannot be secured, it is difficult to control the VCT phase to the intermediate lock phase during idling, so the lock pin fits into the lock hole during the lock mode. If it is determined that the VCT phase is not included, the minimum necessary startability and idle stability are ensured by controlling the VCT phase to the most retarded angle phase or the most advanced angle phase.

  Further, as in claim 7, when it is determined that the lock pin is not fitted into the lock hole during the lock mode, can the hydraulic pressure be maintained so that the VCT phase can be maintained during idling based on the state of the internal combustion engine? The idle rotation speed may be increased when it is determined whether or not the hydraulic pressure capable of maintaining the VCT phase cannot be secured during idling. Even when it is determined that the hydraulic pressure capable of maintaining the VCT phase during idling cannot be secured, if the idling rotational speed is increased, the rotational speed of the oil pump during idling can be increased to ensure the hydraulic pressure capable of retaining the VCT phase. there is a possibility.

  Further, as in claim 8, when it is determined that the lock pin is not fitted into the lock hole during the lock mode, is it possible to secure a hydraulic pressure capable of maintaining the VCT phase during idling based on the state of the internal combustion engine? If it is determined whether or not the hydraulic pressure capable of maintaining the VCT phase can be secured during idling, the VCT phase may be controlled to the intermediate lock phase. If the hydraulic pressure that can maintain the VCT phase during idling can be secured, the VCT phase is maintained at the intermediate lock phase by controlling the VCT phase to the intermediate lock phase even if an abnormal situation has occurred where the lock pin does not protrude. be able to.

  In this case, as in the ninth aspect, it may be determined whether the oil pressure or the cooling water temperature is within a predetermined range, whether or not the hydraulic pressure capable of maintaining the VCT phase can be ensured during idling. For example, in a region where the oil temperature and the cooling water temperature are low, the viscosity (flow resistance) of the hydraulic oil increases, and the oil pressure may be ensured.

  Further, as in claim 10, there may be provided a warning means for warning the driver when a protrusion failure of the lock pin is detected. In this way, when a lock pin protrusion failure occurs, the driver can be warned early, and the driver can be prevented from leaving for a long time without knowing the occurrence of the lock pin protrusion failure. it can.

FIG. 1 is a schematic configuration diagram of the entire control system showing an embodiment of the present invention. FIG. 2 is a longitudinal side view for explaining the configuration of the variable valve timing device and the hydraulic control circuit. FIG. 3 is a longitudinal front view of the variable valve timing device. FIG. 4A is a schematic diagram illustrating a state where the lock pin does not protrude, and FIG. 4B is a schematic diagram illustrating a state where the lock pin protrudes a predetermined amount or more. FIG. 5 (a) is a time chart showing the behavior of the VCT phase when the lock pin is successfully locked by the lock control, and FIG. 5 (b) is that the lock pin protrudes more than a predetermined amount by the lock control, but the lock pin fails to lock. (C) is a time chart showing the behavior of the VCT phase when the lock pin does not protrude. It is a figure explaining the relationship between the magnitude | size of the fluctuation | variation of a VCT phase, a 1st determination value, a 2nd determination value, and the protrusion condition of a lock pin. It is a flowchart which shows the flow of a process of a lock abnormality diagnosis routine. It is a flowchart which shows the flow of a process of a fail safe process routine.

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

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

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

Next, the configuration of the variable valve timing device 18 will be described with reference to FIGS.
A housing 31 of the variable valve timing device 18 is fastened and fixed with bolts 32 to a sprocket 14 that is rotatably supported on the outer periphery of the intake camshaft 16. Thereby, the rotation of the crankshaft 12 is transmitted to the sprocket 14 and the housing 31 via the timing chain 13, and the sprocket 14 and the housing 31 rotate in synchronization with the crankshaft 12.

  On the other hand, a rotor 35 is fastened and fixed to one end of the intake side camshaft 16 with a bolt 37. The rotor 35 is housed in the housing 31 so as to be relatively rotatable.

  As shown in FIG. 3, a plurality of vane storage chambers 40 are formed inside the housing 31, and each vane storage chamber 40 is retarded from the advance chamber 42 by the vane 41 formed on the outer peripheral portion of the rotor 35. It is partitioned into a chamber 43. At both sides of at least one vane 41, a stopper portion 56 is formed that restricts the relative rotation range of the rotor 35 (vane 41) with respect to the housing 31, and the actual VCT phase (cam shaft phase) is adjusted by the stopper portion 56. The most retarded angle phase and the most advanced angle phase of the possible range are regulated. The housing 31 is provided with a spring 55 (see FIG. 2) such as a torsion coil spring that assists the hydraulic pressure that relatively rotates the rotor 35 in the advance angle direction by the spring force during the advance angle control.

  The variable valve timing device 18 is provided with an intermediate lock mechanism 50 that locks the cam shaft phase with an intermediate lock phase located approximately in the middle of the adjustable range. The configuration of the intermediate lock mechanism 50 will be described. Any one or a plurality of vanes 41 is provided with a lock pin accommodation hole 57, and the lock pin accommodation hole 57 has a relative relationship between the housing 31 and the rotor 35 (vane 41). A lock pin 58 for locking the rotation is accommodated so as to protrude, and the lock pin 58 protrudes toward the sprocket 14 and fits into the lock hole 59 of the sprocket 14, so that the cam shaft phase is substantially within the adjustable range. Locked with an intermediate lock phase located in the middle. This intermediate lock phase is set to a phase suitable for starting the engine 11. The lock hole 59 may be provided in the housing 31.

  As shown in FIG. 4, the lock pin 58 is urged in the lock direction (projection direction) by a spring 62 (biasing means). Further, between the outer peripheral portion of the lock pin 58 and the lock pin accommodation hole 57, a lock releasing hydraulic chamber 63 for controlling the oil pressure for driving the lock pin 58 in the unlocking direction is formed. The spring accommodating chamber 64 that accommodates the spring 62 communicates with the atmosphere side (drain side) via the communication hole 65 (drain hole), and the air and oil in the spring accommodating chamber 64 communicate with each other according to the movement of the lock pin 58. It is configured so that it can freely enter and exit through the hole 65.

  The variable valve timing device 18 includes control characteristic variable means for making the VCT phase control characteristic when the lock pin 58 protrudes a predetermined amount or more and the VCT phase control characteristic when the lock pin 58 does not protrude. Yes. Specifically, a communication hole 66 (communication means) for communicating the advance chamber 42 with the spring accommodating chamber 64 of the intermediate lock mechanism 50 is formed in the rotor 35. As shown in FIG. When not projecting, the passage between the communication hole 66 and the spring accommodating chamber 64 is blocked by the lock pin 58 so that the advance chamber 42 is not communicated with the atmosphere side (drain side). As shown in FIG. 4B, when the lock pin 58 protrudes by a predetermined amount or more, the advance chamber 42 communicates with the spring accommodating chamber 64 through the communication hole 66, and the advance chamber 42 is configured to communicate with the atmosphere side (drain side). In this case, even if the lock pin 58 does not protrude until the lock pin 58 is fitted in the lock hole 59, the lock pin 58 can be moved as long as the end of the lock pin 58 protrudes to a position where it abuts against the inner wall surface of the lock hole 59. 58 is configured to protrude beyond a predetermined amount.

  Thereby, when the lock pin 58 is not fitted in the lock hole 59 during the lock mode, the variation of the VCT phase due to the torque of the intake camshaft 16 when the lock pin 18 protrudes a predetermined amount or more is The lock pin 18 is configured to be larger than when it does not protrude.

  In the present embodiment, the hydraulic control device that controls the hydraulic pressure that drives the variable valve timing device 18 and the lock pin 58 includes a hydraulic control valve 25 for phase control that controls the hydraulic pressure that drives the variable valve timing device 18, and a lock pin. The hydraulic control valve 26 for lock control for controlling the hydraulic pressure for driving the 58 is individually provided. The hydraulic pressure control valve 25 for phase control is constituted by, for example, a 5-port, 3-position type spool valve, and the hydraulic pressure control valve 26 for lock control is constituted by, for example, a 3-port, 2-position type spool valve.

  The oil (operating oil) in the oil pan 27 is pumped up by an oil pump 28 driven by the power of the engine 11 and supplied to the hydraulic control valves 25 and 26. The variable valve timing is controlled by the hydraulic control valve 25 for phase control. The hydraulic pressure (oil amount) supplied to the advance chamber 42 and the retard chamber 43 of the device 18 is controlled, and the hydraulic pressure (oil amount) for driving the lock pin 58 in the unlocking direction is controlled by the hydraulic control valve 26 for lock control. Is done. A check valve 29 is provided on the inlet port side of the phase control hydraulic control valve 25 to prevent oil backflow.

  It should be noted that a hydraulic control valve in which the phase control hydraulic control valve 25 and the lock control hydraulic control valve 26 are integrated may be used.

  The engine control circuit 21 functions as variable valve timing control means in the claims, and calculates a target VCT phase (target valve timing) based on engine operating conditions during variable valve timing control (phase feedback control). Thus, for example, the control duty (control amount) of the hydraulic control valve 25 for phase control is set so that the actual VCT phase of the intake camshaft 16 (actual valve timing of the intake valve) matches the target VCT phase (target valve timing). Feedback control is performed on the hydraulic pressure supplied to the advance chamber 42 and the retard chamber 43 of the variable valve timing device 18 by feedback control by PD control or the like.

  Further, the engine control circuit 21 also functions as a lock control means in the claims, and lock control for controlling the hydraulic control valve 26 for lock control so that the lock pin 58 protrudes when a lock request is generated. Execute. Specifically, as shown in FIG. 4 (a), when a lock request is generated, the target VCT phase is set to a phase that is delayed by a predetermined amount from the intermediate lock phase in anticipation of an advance operation during the lock mode. Then, the control of the retard mode for driving the actual VCT phase in the retard direction is started, the hydraulic pressure of the hydraulic chamber 63 for unlocking the intermediate lock mechanism 50 is released, and the lock pin 58 is locked by the spring 62 Energize in the direction to project.

  In the state where the actual VCT phase does not coincide with the intermediate lock phase, as shown in FIG. 4B, the tip of the lock pin 58 only protrudes to a position where it abuts against the inner wall surface of the outer periphery of the lock hole 59. In this state, the lock pin 58 protrudes by a predetermined amount or more, the advance chamber 42 communicates with the spring accommodating chamber 64 through the communication hole 66, and the advance chamber 42 is on the atmosphere side (drain side). It will be in the state connected with.

  Locked from the retard mode when it is determined that the actual VCT phase has clearly passed the intermediate lock phase in the retard direction by the retard mode control (for example, when a predetermined time has elapsed since the start of the retard mode control). Switch to mode and gradually advance the actual VCT phase. As a result, when the actual VCT phase matches the intermediate lock phase, the lock pin 58 matches the lock hole 59 and the lock pin 58 fits into the lock hole 59 so that the actual VCT phase is locked at the intermediate lock phase. It will be in the state.

  Further, the engine control circuit 21 executes a lock abnormality diagnosis routine shown in FIG. 7 to be described later to determine the protrusion state of the lock pin 58 based on the behavior of the actual VCT phase during the lock mode, and based on the determination result. Thus, the lock state, the lock failure (the phase mismatch between the lock pin 58 and the lock hole 59), and the protrusion failure (retraction) of the lock pin 58 are determined.

  As described above, by providing the communication hole 66 that allows the advance chamber 42 to communicate with the spring accommodating chamber 64 of the intermediate lock mechanism 50, the lock pin 58 is not fitted into the lock hole 59 during the lock mode. The variation of the VCT phase due to the cam torque when the lock pin 18 protrudes a predetermined amount or more is configured to be larger than when the lock pin 18 does not protrude. As a result, when the lock pin 58 is not fitted in the lock hole 59 during the lock mode, the cause is the mismatch of the phases of the lock pin 58 and the lock hole 59, or the protrusion of the lock pin 58 ( It is possible to determine whether the VCT phase fluctuation is large or small.

  Specifically, as shown in FIG. 6, when the state in which the variation in the VCT phase is equal to or lower than the first determination value continues during the lock mode, the lock pin 58 is locked in the lock hole 59. If it is determined that there is a state in which the variation in the VCT phase is greater than or equal to the second determination value that is greater than the first determination value during the lock mode, the lock pin 58 is projected only by a predetermined amount or more. 58 is not fitted in the lock hole 59 (the phase mismatch between the lock pin 58 and the lock hole 59), and the variation of the VCT phase during the lock mode is the first determination value and the second determination. When the state within the range of the value continues, it is determined that the protrusion of the lock pin 58 is defective (retracted).

  The determination of the degree of protrusion of the lock pin 58 described above is executed by the engine control circuit 21 by the lock abnormality diagnosis routine of FIG.

  The lock abnormality diagnosis routine of FIG. 7 is executed at a predetermined cycle during engine operation, and functions as a lock pin protrusion degree determination means in the claims. When this routine is started, it is first determined in step 101 whether or not a lock request has occurred. If it is determined that a lock request has not occurred, this routine is directly executed without performing the subsequent processing. Exit.

  On the other hand, if it is determined in step 101 that a lock request has occurred, the process proceeds to step 102, where it is determined whether or not a shift from the retarded mode to the lock mode is made depending on whether or not a predetermined time has elapsed since the lock request was generated. To do. When a lock request is generated, a delay control mode (not shown) sets the target VCT phase to a phase that is retarded by a predetermined amount from the intermediate lock phase, and drives the actual VCT phase in the retard direction. And the hydraulic pressure of the unlocking hydraulic chamber 63 of the intermediate lock mechanism 50 is released, and the lock pin 58 is urged and projected in the locking direction by the spring 62. After a predetermined time has elapsed since the lock request was generated. Transition from retard mode to lock mode.

  If it is determined in step 102 that a predetermined time has not elapsed since the generation of the lock request, it is determined that the lock mode has not yet been entered, and this routine is immediately terminated.

  Thereafter, when a predetermined time has elapsed from the occurrence of the lock request, it is determined that the mode has shifted to the lock mode, the process proceeds from step 102 to step 103, and the first determination value and the second determination value are set to the oil temperature, cooling water temperature, engine speed. Based on at least one of the velocities, a map or a mathematical formula is used. For example, the oil viscosity (flow resistance) changes according to the oil temperature and the cooling water temperature, and the hydraulic pressure supplied to the advance chamber 42 and the retard chamber 43 of the variable valve timing device 18 changes. Accordingly, the fluctuation range of the VCT phase changes. In addition, since the oil pressure changes by changing the rotation speed (discharge amount) of the oil pump 28 that pumps oil according to the engine rotation speed, the fluctuation range of the VCT phase changes according to the engine rotation speed. Therefore, if the first determination value and the second determination value are set based on at least one of the oil temperature, the cooling water temperature, and the engine rotation speed, the first determination value and the second determination value are set as the oil viscosity and the oil An appropriate value can be set according to the rotational speed (discharge amount) of the pump 28.

  Thereafter, the process proceeds to step 104, and the fluctuation range of the VCT phase during the lock mode is calculated. At this time, the average value of the fluctuation width of the VCT phase for a predetermined time may be calculated, or the fluctuation width of the VCT phase may be calculated by annealing. Thereafter, the process proceeds to step 105, where it is determined whether or not the fluctuation range of the VCT phase is equal to or smaller than the first determination value (see FIG. 6). It is determined that the phase is constrained to a constant phase, and the routine proceeds to step 106, where it is determined whether or not the actual VCT phase is in the vicinity of the intermediate lock phase (within a predetermined range from the intermediate lock phase). As a result, if it is determined that the actual VCT phase is in the vicinity of the intermediate lock phase, it is determined that the lock pin 58 is in the locked state in which the lock pin 58 is fitted in the lock hole 59, and the process proceeds to step 107 to determine that the lock is completed.

  On the other hand, if it is determined in step 106 that the actual VCT phase is not in the vicinity of the intermediate lock phase, the tip of the lock pin 58 is caught in a place other than the lock hole 59 and the actual VCT phase is a phase other than the intermediate lock phase. If it is determined that it is restrained, the process proceeds to step 108, where it is determined that the lock is out of the lock hole, and lock control is re-executed in the next step 109. Thereafter, when this routine is started, in step 101, it is determined that a lock control re-execution command is a lock request occurrence, and the processing from step 102 described above is repeated.

  On the other hand, if it is determined in step 105 that the variation range of the VCT phase is equal to or greater than the first determination value, the process proceeds to step 110, and whether or not the variation range of the VCT phase is equal to or greater than the second determination value (see FIG. 6). If the fluctuation range of the VCT phase is equal to or greater than the second determination value, the lock pin 58 is not fitted into the lock hole 59 because the lock pin 58 protrudes a predetermined amount or more (the lock pin 58 and the lock hole 58). 59). Then, the process proceeds to step 111 to determine whether or not the actual VCT phase is on the advance side (larger) than the intermediate lock phase. If the actual VCT phase is determined to be on the advance side with respect to the intermediate lock phase, the process proceeds to step 112. Then, it is determined that the lock pin 58 has passed through the lock hole 59. If it is determined in step 111 that the actual VCT phase is retarded from the intermediate lock phase, the process proceeds to step 113 and it is determined that the lock pin 58 has not reached the lock hole 59. Thereafter, the process proceeds to step 109, and lock control is re-executed.

  In this way, when a lock failure occurs due to a phase mismatch between the lock pin 58 and the lock hole 59, the lock control is re-executed, so that the phases of the lock pin 58 and the lock hole 59 are matched to each other. 58 lock operations can be successful. At this time, the number of re-execution of the lock control may be only one time, or the re-execution of the lock control may be repeated within a range not exceeding a preset maximum number until the lock operation of the lock pin 58 is successful. .

  On the other hand, when it is determined as “No” in both step 105 and step 110, that is, when the fluctuation range of the VCT phase is within the range between the first determination value and the second determination value. Then, the process proceeds to step 114, where it is determined that the lock pin 58 is not projecting (retracted), and in the next step 115, the warning lamp 70 (warning means) is turned on or blinked, or the instrument panel display section ( A warning is displayed on the warning means) and the driver is warned and the abnormality information is stored in a rewritable nonvolatile memory such as a backup RAM of the engine control circuit 21 (stored data even when the engine control circuit 21 is powered off). To the rewritable storage means). Thereafter, the process proceeds to step 116, and the fail-safe processing routine of FIG. 8 is executed.

  When the fail-safe processing routine of FIG. 8 is activated, first, at step 201, it is determined based on the state of the engine 11 whether or not a hydraulic pressure capable of maintaining the VCT phase can be secured during idling. At this time, whether or not the hydraulic pressure capable of maintaining the VCT phase during idling can be ensured may be determined based on whether or not the oil temperature or the cooling water temperature is within a predetermined range. For example, in a region where the oil temperature and the cooling water temperature are low, the viscosity (flow resistance) of the oil increases and the oil pressure may be ensured.

  If it is determined in step 201 that a hydraulic pressure capable of maintaining the VCT phase at the time of idling can be secured, the process proceeds to step 202, and the VCT phase is controlled to an intermediate lock phase at the time of idling. Thereby, even if an abnormal situation where the lock pin 58 does not protrude occurs, the VCT phase can be held at the intermediate lock phase.

  On the other hand, if it is determined in step 201 that the hydraulic pressure capable of maintaining the VCT phase cannot be secured during idling, it is difficult to control the VCT phase to the intermediate lock phase during idling, so the process proceeds to step 203. During idling, the VCT phase is controlled to the most retarded phase that is the limit phase in the direction in which the torque of the intake camshaft 16 acts. This ensures the minimum necessary startability and idle stability.

  Alternatively, the idle rotation speed may be increased in step 203 described above. Even when it is determined that the hydraulic pressure capable of maintaining the VCT phase during idling cannot be secured, if the idle rotational speed is increased, the rotational speed of the oil pump 28 during idling is increased, and the hydraulic pressure capable of maintaining the VCT phase is increased. There is a possibility that it can be secured.

  According to the present embodiment described above, the VCT phase control characteristic when the lock pin 58 protrudes by a predetermined amount or more and the VCT phase control characteristic when the lock pin 58 does not protrude are configured differently. Since the VCT phase control characteristic differs depending on whether or not the lock pin 58 protrudes a predetermined amount or more during the lock mode, the behavior of the VCT phase differs. It is possible to determine whether or not the protrusion exceeds the fixed amount. As a result, the protruding state of the lock pin 58 can be confirmed during the lock mode, the locked state, the lock failure (the phase mismatch between the lock pin 58 and the lock hole 59), and the protrusion failure (retraction) of the lock pin 58. Release).

  Although this embodiment is an embodiment in which the present invention is applied to a variable valve timing apparatus for an intake valve, the present invention may be applied to a variable valve timing control apparatus for an exhaust valve. When the present invention is applied to a variable valve timing control device for an exhaust valve, the control direction of the VCT phase of the exhaust valve (relation between “advance” and “retard”) is opposite to the control direction of the VCT phase of the intake valve. You can do it. For example, when it is determined in fail-safe processing that a hydraulic pressure that can maintain the VCT phase of the exhaust valve cannot be secured during idling, the VCT phase of the exhaust valve is a limit phase in the direction in which the torque of the exhaust camshaft 17 acts. What is necessary is just to control to the most advanced angle phase.

  In addition, the present invention can be variously modified within the scope not departing from the gist, such as the configuration of the variable valve timing device 18, the configuration of the control characteristic variable means, the configuration of the hydraulic control valves 25 and 26, etc. Needless to say, it can be implemented.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Crankshaft, 13 ... Timing chain, 14, 15 ... Sprocket, 16 ... Intake camshaft, 17 ... Exhaust camshaft, 18 ... Variable valve timing device (VCT), 19 ... Cam angle Sensor 20, crank angle sensor 21, engine control circuit (lock pin protrusion degree determining means, lock control means) 25, hydraulic control valve for phase control (hydraulic control device) 26, hydraulic control valve for lock control (Hydraulic control device), 28 ... oil pump, 31 ... housing, 35 ... rotor, 40 ... fluid chamber, 41 ... vane, 42 ... advance chamber, 43 ... retard chamber, 50 ... intermediate lock mechanism, 55 ... spring, 58 ... Lock pin, 59 ... Lock hole, 62 ... Spring (biasing means), 63 ... Hydraulic chamber for unlocking, 64 ... Spring accommodating chamber, 65 ... Communication hole, 66 ... Communication (Communication means), 70 ... warning lamp (warning means)

Claims (10)

A hydraulically driven variable valve timing device that adjusts the valve timing by changing the rotational phase of the camshaft relative to the crankshaft of the internal combustion engine (hereinafter referred to as “VCT phase”), and an intermediate lock that positions the VCT phase within its adjustable range In a variable valve timing control device for an internal combustion engine comprising: a lock pin that locks in phase; and a hydraulic control device that controls the hydraulic pressure that drives the variable valve timing device and the lock pin;
Control characteristic variable means for making the VCT phase control characteristic when the lock pin protrudes a predetermined amount or more different from the VCT phase control characteristic when the lock pin does not protrude;
Lock control means for executing lock control for controlling the hydraulic control device to project the lock pin when a lock request occurs, and continuing a lock mode for holding the lock state until the lock request is released; ,
A variable valve timing control device for an internal combustion engine, comprising: a lock pin protrusion degree determining means for determining a protrusion degree of the lock pin based on the behavior of the VCT phase during the lock mode.   The control characteristic variable means is provided with a communication means in a hydraulic chamber to which hydraulic oil for driving the VCT phase to the advance side or the retard side is supplied, and the lock pin protrudes a predetermined amount or more. When the hydraulic chamber communicates with the outside through the communication means, the lock pin protrudes a predetermined amount or more when the lock pin is not fitted in the lock hole during the lock mode. 2. The configuration according to claim 1, wherein the variation of the VCT phase due to the torque of the cam shaft when in a state is larger than that in a state where the lock pin does not protrude. Variable valve timing control device for internal combustion engine.   The lock pin protrusion state determining means determines that the lock pin is in a locked state in which the lock pin is fitted in the lock hole when the state in which the variation in the VCT phase is equal to or less than the first determination value continues during the lock mode. And when the state in which the variation of the VCT phase is greater than or equal to the second determination value greater than the first determination value continues during the lock mode, the lock pin protrudes by a predetermined amount or more and the lock pin is Means for determining that the lock pin is not fitted in the lock hole, and the lock pin when the state in which the fluctuation of the VCT phase is within the range between the first determination value and the second determination value during the lock mode continues. The variable valve timing control device for an internal combustion engine according to claim 2, further comprising means for determining that the protrusion is defective.   The lock pin protrusion degree determining means includes means for setting the first determination value and the second determination value based on at least one of oil temperature, cooling water temperature, and internal combustion engine rotation speed. The variable valve timing control device for an internal combustion engine according to claim 3.   During the lock mode, it is determined whether the VCT phase is the intermediate lock phase, and based on the determination result and the lock pin protrusion state determination means determined by the lock pin protrusion state determination means, the lock succeeds and fails. 5. The variable valve for an internal combustion engine according to claim 1, further comprising: means for recognizing a lock failure, and means for re-execution of lock control by the lock control means when it is determined that the lock has failed. Timing control device.   The lock pin protrusion degree determining means secures a hydraulic pressure capable of maintaining the VCT phase during idling based on the state of the internal combustion engine when it is determined that the lock pin is not fitted in the lock hole during the lock mode. And a means for controlling the VCT phase to the most retarded angle phase or the most advanced angle phase when it is determined that the hydraulic pressure capable of maintaining the VCT phase cannot be secured during idling. 6. A variable valve timing control device for an internal combustion engine according to any one of 1 to 5.   The lock pin protrusion degree determining means secures a hydraulic pressure capable of maintaining the VCT phase during idling based on the state of the internal combustion engine when it is determined that the lock pin is not fitted in the lock hole during the lock mode. 6. The apparatus according to claim 1, further comprising: a unit configured to determine whether or not it is possible to increase the idle rotation speed when it is determined that the hydraulic pressure capable of maintaining the VCT phase cannot be secured during idling. A variable valve timing control device for an internal combustion engine.   The lock pin protrusion degree determining means secures a hydraulic pressure capable of maintaining the VCT phase during idling based on the state of the internal combustion engine when it is determined that the lock pin is not fitted in the lock hole during the lock mode. 8. The apparatus according to claim 1, further comprising means for controlling whether the VCT phase can be maintained at the intermediate lock phase when it is determined whether the hydraulic pressure capable of maintaining the VCT phase can be secured during idling. A variable valve timing control device for an internal combustion engine according to claim 1.   The lock pin protrusion degree judging means has means for judging whether oil pressure or cooling water temperature is within a predetermined range as to whether or not a hydraulic pressure capable of maintaining the VCT phase can be secured during idling. The variable valve timing control device for an internal combustion engine according to any one of claims 6 to 8.   The internal combustion engine according to any one of claims 1 to 9, further comprising warning means for warning a driver when the lock pin protrusion degree determination means detects a protrusion failure of the lock pin. Variable valve timing control device.

Images