JP5408505B2 - Variable valve timing control device for internal combustion engine - Google Patents

Description

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

  Recently, in an internal combustion engine mounted on a vehicle, a hydraulically driven variable valve timing that changes the valve timing (opening / closing timing) of an intake valve and an exhaust valve of the internal combustion engine for the purpose of improving output, reducing fuel consumption, and reducing emissions. The number of devices equipped with equipment is increasing. This hydraulically driven variable valve timing device drives the variable valve timing device as described in Patent Document 1 (Japanese Patent Laid-Open No. 2007-224744) and Patent Document 2 (Japanese Patent Laid-Open No. 2004-251254). When calculating the control amount (control duty) of the hydraulic control valve that controls the hydraulic pressure to be controlled, the feedback control amount according to the deviation between the target valve timing (target VCT phase) and the actual valve timing (actual VCT phase) The control amount of the hydraulic control valve is set based on the holding control amount (holding duty) necessary to hold the valve timing constant, and the hydraulic control valve is driven by this control amount to advance the variable valve timing device. The valve timing is advanced or retarded by changing the flow rate (hydraulic pressure) of hydraulic oil supplied to the chamber or the retard chamber.

  At this time, the holding control amount is learned in consideration of fluctuations in the holding control amount due to manufacturing variations and changes over time of the variable valve timing device and the hydraulic control valve. In the conventional holding control amount learning process, when the actual valve timing is substantially consistent with the target valve timing and stable (when the deviation between the two continues within a predetermined value), the hydraulic control valve at that time The control amount is learned as a holding control amount, and the learning value of the holding control amount is updated and stored in the memory.

  Further, in the hydraulically driven variable valve timing device, as described in Patent Document 3 (Japanese Patent Laid-Open No. 9-324613) and Patent Document 4 (Japanese Patent Laid-Open No. 2001-159330), the engine is stopped. In some cases, the lock phase is set approximately in the middle of the adjustable range of the VCT phase to expand the adjustable range of the valve timing (VCT phase). In this system, the intermediate lock phase that is locked when the engine is stopped is set to a phase that is suitable for starting, and the engine is started with this intermediate lock phase. Then, the lock is released and the VCT phase is feedback-controlled to the target VCT phase set according to the engine operating state. Then, lock control for locking the VCT phase with the intermediate lock phase is executed when the engine is stopped or when a lock request is generated during idle operation.

JP 2007-224744 A JP 2004-251254 A JP-A-9-324613 JP 2001-159330 A

  In order to ensure that the VCT phase is locked at the intermediate lock phase when the lock request is generated, the applicant assigns the VCT phase to the pre-lock phase that has once passed the intermediate lock phase by a predetermined amount when the lock request occurs ( After performing lock pre-lock phase control (phase control at the time of lock request) to move to the target phase), lock pin protrusion control is performed so that the lock pin protrudes while returning the VCT phase toward the intermediate lock phase. Research and development of lock control technology for locking the phase with an intermediate lock phase (Japanese Patent Application No. 2009-178292).

  As shown in FIG. 6, when the pre-lock phase control is performed in response to the generation of the lock request, if the learning value of the hold control amount (hold duty) is large, the VCT phase is accurately set to the pre-lock phase. There is a possibility that the control cannot be performed and the VCT phase converges to a position shifted from the pre-lock phase. In such a case, when learning of the hold control amount is executed by normal hold control amount learning and the learning value of the hold control amount is corrected thereafter, the VCT phase can be accurately controlled to the pre-lock phase. , The VCT phase reaches the pre-lock phase. However, in this case, since the time from when the lock request occurs until the VCT phase reaches the pre-lock phase (execution time of the pre-lock phase control) becomes long, the start timing of the lock pin protrusion control is delayed accordingly, There is a problem that the time until completion (time until the VCT phase is locked with the intermediate lock phase) becomes long.

  Therefore, the problem to be solved by the present invention is to provide a variable valve timing control device for an internal combustion engine that can suppress an increase in the time until lock completion when the learning value of the holding control amount is shifted at the time of lock request. Is to provide.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a hydraulically driven variable valve that adjusts the valve timing by changing the rotational phase of the camshaft (hereinafter referred to as “VCT phase”) with respect to the crankshaft of the internal combustion engine. Timing device, lock pin that locks the VCT phase with an intermediate lock phase located within the adjustable range, a hydraulic control valve that controls the hydraulic pressure that drives the variable valve timing device and the lock pin, and predetermined holding control amount learning execution Holding control amount learning means for performing normal holding control amount learning for learning a holding control amount necessary to hold the VCT phase constant when the condition is satisfied, and the learning value of the holding control amount In a variable valve timing control device for an internal combustion engine that controls a hydraulic control valve based on the control signal to control a VCT phase, a VCT position is generated when a lock request is generated. The lock pin protrusion control is performed so that the lock pin protrudes while returning to the intermediate lock phase after performing the pre-lock phase control that moves the intermediate lock phase to the pre-lock phase that has passed the predetermined amount by the VCT phase. Lock control means for controlling so as to be locked at the intermediate lock phase, and the lock control means executes hold control amount learning value correction for correcting the learning value of the hold control amount during the pre-lock phase control, and this hold control The hydraulic control valve is controlled based on the learning value of the holding control amount corrected by the amount learning value correction.

  In this configuration, even when the learning value of the holding control amount is shifted when performing the pre-locking phase control due to the generation of the lock request, the holding control amount that corrects the learning value of the holding control amount during the pre-locking phase control. By executing the learning value correction, the learning value of the holding control amount can be corrected earlier than the normal holding control amount learning. Based on the learning value of the holding control amount corrected by the holding control amount learning value correction. By controlling the hydraulic control valve, it is possible to suppress an increase in the time from when the lock request is generated until the VCT phase reaches the pre-lock phase (pre-lock phase control execution time). Thereby, the delay of the start time of lock pin protrusion control can be reduced, and it can be suppressed that the time until lock completion (time until the VCT phase is locked with the intermediate lock phase) is lengthened.

  During the pre-lock phase control, the convergence accuracy to the target phase is not required to be the same level as during normal phase control, so the holding control amount learning accuracy is not required to be the same level as during normal phase control. Therefore, as in claim 2, the holding control amount learning value correction is performed by learning the holding control amount by changing the condition to allow the holding control amount to be learned earlier than the normal holding control amount learning during the pre-lock phase control. You may make it do. In this way, priority is given to learning the holding control amount earlier than the learning accuracy of the holding control amount, and the holding control amount is changed to a condition that allows the holding control amount to be learned earlier than normal holding control amount learning. Learning, correction of the holding control amount learning value for correcting the learning value of the holding control amount can be performed, and the learning value of the holding control amount can be corrected earlier than normal holding control amount learning.

  Alternatively, the hold control amount learning value correction may be performed by updating the hold control amount learning value in a direction in which the VCT phase approaches the pre-lock phase during the pre-lock phase control. . In this way, the holding control that corrects the learning value of the holding control amount by updating the learning value of the holding control amount in a direction in which the VCT phase approaches the pre-locking phase before the holding control amount learning execution condition is satisfied. The amount learning value correction can be performed, and the learning value of the holding control amount can be corrected earlier.

  By the way, when the holding control amount learning value correction is executed even though the learning value of the holding control amount is normal (a state in which the deviation of the learning value of the holding control amount is small), the convergence of the VCT phase to the pre-lock phase is instead performed. May deteriorate.

  Therefore, as described in claim 4, when the execution time of the pre-lock phase control exceeds a predetermined determination time, the hold control amount learning value correction may be executed. That is, when the execution time of the pre-lock phase control is within the determination time, the learning value of the holding control amount may be normal (the deviation of the learning value of the holding control amount is small). When correction is not performed but the execution time of the pre-lock phase control exceeds the determination time (that is, when the VCT phase does not reach the pre-lock phase within a predetermined time from the start of the pre-lock phase control) Then, it is determined that the deviation of the learning value of the holding control amount is large, and the holding control amount learning value correction is executed. As a result, it is possible to prevent the holding control amount learning value correction from being executed even though the learning value of the holding control amount is normal, and the convergence of the VCT phase to the pre-lock phase can be achieved by the holding control amount learning value correction. The situation of getting worse can be avoided.

  In a system that executes normal phase control for controlling the hydraulic control valve so that the VCT phase matches the target VCT phase set according to the operating condition when a predetermined phase control execution condition is satisfied, When the pre-lock phase control is performed with the same responsiveness as the above phase control, it takes time to move the VCT phase to the pre-lock phase, and the time to lock completion becomes long.

  Therefore, as in claim 5, when the pre-lock phase control is performed, the control amount of the hydraulic control valve may be set to a control amount different from that during normal phase control. In this way, it is possible to shorten the time until lock completion by accelerating the responsiveness of the pre-lock phase control.

  In addition, the learning value of the holding control amount corrected by the holding control amount learning value correction during the pre-lock phase control may have a reduced learning accuracy. There is a possibility that the phase control accuracy of the phase control will deteriorate.

  Therefore, as described in claim 6, the learning value of the holding control amount corrected by the holding control amount learning value correction during the pre-locking phase control may not be reflected in the normal phase control. By doing so, it is possible to prevent the phase control accuracy of the normal phase control from being deteriorated by the learning value of the holding control amount corrected by the holding control amount learning value correction during the pre-lock phase control.

FIG. 1 is a schematic configuration diagram of the entire engine control system used in the first to fourth embodiments 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. 4 is a view for explaining the functions of the lock pin (advance limit pin) and the retard limit pin. FIG. 5 is a diagram for explaining the control characteristics of the variable valve timing device. FIG. 6 is a time chart for explaining a problem when the hold duty learning value is shifted at the time of the lock request. FIG. 7 is a flowchart showing the flow of processing of the lock control routine of the first embodiment. FIG. 8 is a flowchart illustrating the processing flow of the holding duty learning value correction routine according to the first embodiment. FIG. 9 is a time chart illustrating an execution example of the hold duty learning value correction according to the first embodiment. FIG. 10 is a flowchart illustrating the processing flow of the holding duty learning value correction routine according to the second embodiment. FIG. 11 is a time chart illustrating an execution example of the hold duty learning value correction according to the second embodiment. FIG. 12 is a flowchart illustrating the processing flow of the lock control routine according to the third embodiment. FIG. 13 is a time chart illustrating an execution example of lock control according to the third embodiment. FIG. 14 is a time chart for explaining a holding duty learning value for lock control according to the fourth embodiment.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

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

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

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

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 variable valve timing device 18 is provided with an intermediate lock mechanism 50 that locks the VCT phase at an intermediate lock phase located between the most retarded angle phase and the most advanced angle phase of the adjustable range (for example, substantially in the middle). Yes. The configuration of the intermediate lock mechanism 50 will be described. Any one (or a plurality of) vanes 41 are provided with a lock pin accommodation hole 57, and the lock pin accommodation hole 57 has a housing 31, a rotor 35 (vane 41), and the like. A lock pin 58 for locking the relative rotation of the sprocket 14 is accommodated so as to protrude, and the lock pin 58 protrudes toward the sprocket 14 and fits into the lock hole 59 (see FIG. 4) of the sprocket 14, so that the VCT phase is It is locked at an intermediate lock phase located approximately in the middle of the adjustable range. 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 the spring 62. Further, between the outer peripheral portion of the lock pin 58 and the lock pin accommodation hole 57, an unlocking hydraulic chamber for controlling the hydraulic pressure for driving the lock pin 58 in the unlocking direction is formed.

  In the first embodiment, the lock pin 58 also functions as an advance limit pin that prevents the VCT phase controlled on the retard side from the intermediate lock phase from inadvertently moving beyond the intermediate lock phase to the advance side. Then, the advance angle limiting groove 63 shallower than the lock hole 59 is formed so as to extend continuously to the predetermined phase C near the most retarded angle phase, and the lock pin 58 (advance angle limit pin). ) Is fitted in the advance angle limiting groove 63, the range of the VCT phase controlled on the retard side from the intermediate lock phase is limited to the range from the intermediate lock phase to the predetermined phase C near the most retarded phase. It is like that.

  When the target phase exceeds the predetermined phase C and is set to the most retarded phase side, the lock pin 58 (advance angle limiting pin) is extracted from the advance angle limiting groove 63 by hydraulic pressure, so that the VCT phase is the most retarded angle. Move to the phase side. Further, when the target phase is set to the advance side with respect to the intermediate lock phase, the lock pin 58 (advance limit pin) is completely extracted from the lock hole 59 by hydraulic pressure, and the VCT phase is advanced from the intermediate lock phase. To move to the side.

  Similarly, a retard limit pin 64 that prevents the VCT phase controlled on the advance side from inadvertently moving to the retard side and, for example, two stages of retard limit grooves 65 a and 65 b are provided. By fitting the angle limiting pin 64 into one of the retardation limiting grooves 65a and 65b, the range of the VCT phase controlled on the advance side is limited to, for example, two stages.

  One of the two-stage retardation restriction grooves 65a and 65b may be omitted to provide only one retardation restriction groove, or three or more retardation restriction grooves. Further, the advance angle limiting groove 63, the retard angle limiting grooves 65a and 65b, and the retard angle limiting pin 64 may be omitted.

  In the configuration example of FIG. 4, the retard angle limiting grooves 65a and 65b extend from the most advanced angle phase to the predetermined phase B and A on the retard angle side beyond the intermediate lock phase. The advance angle limit pin) and the retard angle limit pin 64 are fitted into the lock hole 59 and the second angle (the deeper groove) delay angle limit groove 65b, respectively.

  Further, as shown in FIG. 2, the housing 31 includes a spring 55 such as a torsion coil spring as an urging means for assisting (assisting) the hydraulic pressure for relatively rotating the rotor 35 in the advance angle direction during advance angle control. Is provided. In the variable valve timing device 18 for the intake valve, the torque of the intake side camshaft 16 acts in a direction that retards the VCT phase. Therefore, the spring 55 has a direction opposite to the torque direction of the intake side camshaft 16. Will be urged in the advance direction.

  In the first embodiment, as shown in FIG. 4, the range in which the urging force of the spring 55 acts is set to the range from the most retarded phase to the almost intermediate lock phase, and restart after an abnormal stop such as engine stall Assuming the fail safe at the time, when starting with the actual VCT phase retarded from the intermediate lock phase with the lock pin 58 removed from the lock hole 59, during the cranking by the starter (not shown), The spring 55 is configured so that the lock pin 58 can be fitted into the lock hole 59 and locked by assisting the advance operation of advancing the actual VCT phase from the retard side to the intermediate lock phase by the spring force of the spring 55.

  On the other hand, when starting with the actual VCT phase on the advance side from the intermediate lock phase, the torque on the intake side camshaft 16 acts in the retarding direction during cranking, so the actual VCT phase is caused by the torque on the intake side camshaft 16. Can be retarded from the advance side to the intermediate lock phase to lock the lock pin 58 into the lock hole 59.

  In the first embodiment, the hydraulic control valve 25 that controls the VCT phase of the variable valve timing device 18 and the hydraulic pressure that drives the lock pin 58 and the retard limit pin 64 controls the phase control that controls the hydraulic pressure that drives the VCT phase. An oil pressure control valve integrated with a hydraulic pressure control valve function for locking and a hydraulic pressure control valve function for controlling the lock to control the hydraulic pressure for driving the lock pin 58, and by an oil pump 28 driven by the power of the engine 11, Oil (operating oil) in the oil pan 27 is pumped up and supplied to the hydraulic control valve 25. The hydraulic control valve 25 is constituted by, for example, an 8-port / four-position type spool valve, and, as shown in FIG. 5, the lock modes L1, L2, the advance mode are controlled according to the control duty (control amount) of the hydraulic control valve 25. The control area is divided into four control areas: angular mode A, holding mode H, and retarding mode R.

  In the control region of the lock modes L1 and L2, the oil supply oil passage to the unlocking hydraulic chamber in the lock pin accommodating hole 57 is shut off, and the hydraulic pressure in the unlocking hydraulic chamber in the lock pin accommodating hole 57 is released. The lock pin 58 is protruded in the locking direction by the spring 62.

  Furthermore, the control region of the lock modes L1 and L2 is the control region of the oil filling mode L1 that supplies oil to the advance chamber 42 by opening the oil supply oil passage to the advance chamber 42 while protruding the lock pin 58. The lock pin 58 is projected into the control region of the lock holding mode L2 in which the oil supply oil passages of both the advance chamber 42 and the retard chamber 43 are shut off and the oil pressure in the chambers 42, 43 is maintained. Yes.

  In the control region of the advance angle mode A, the oil supply oil passage to the retard chamber 43 is shut off, the retard port of the hydraulic control valve 25 is connected to the drain port, and the oil pressure in the retard chamber 43 is released. According to the control duty of the hydraulic control valve 25, the oil supply oil passage to the advance chamber 42 is opened, oil is supplied to the advance chamber 42, and the oil pressure in the advance chamber 42 is changed to change the actual VCT phase. Advance the angle.

  In the control region of the holding mode H, the oil supply oil passages of both the advance chamber 42 and the retard chamber 43 are shut off, and the oil pressures of both the chambers 42 and 43 are held so that the actual VCT phase does not move. .

  In the control region of the retard angle mode R, the oil supply oil passage to the advance chamber 42 is shut off, the advance port of the hydraulic control valve 25 is connected to the drain port, and the hydraulic pressure in the advance chamber 42 is released. According to the control duty of the hydraulic control valve 25, the oil supply oil passage to the retard chamber 43 is opened, oil is supplied to the retard chamber 43, and the hydraulic pressure in the retard chamber 43 is changed to change the actual VCT phase. Is retarded.

  In the control region other than the lock modes L1 and L2 (advance mode A, hold mode H, retard mode R), the oil supply oil passage to the lock release hydraulic chamber in the lock pin accommodation hole 57 is opened to release the lock. The hydraulic chamber is filled with oil to increase the hydraulic pressure in the unlocking hydraulic chamber, and the lock pin 58 is extracted from the lock hole 59 by the hydraulic pressure to unlock the lock pin 58.

  In the first embodiment, the control mode is switched in the order of the lock modes L1 and L2, the advance mode A, the hold mode H, and the retard mode R as the control duty of the hydraulic control valve 25 increases. However, for example, as the control duty of the hydraulic control valve 25 increases, the control mode is switched in the order of the retard mode R, the holding mode H, the advance mode A, the lock modes L1 and L2, or The control mode may be switched in the order of the lock modes L1, L2, the retard mode R, the holding mode H, and the advance mode A by switching the order of the retard mode R and the advance mode A.

  The engine control circuit 21 functions as VCT phase control means in the claims, and when a predetermined phase control execution condition is satisfied, the actual VCT phase of the intake side camshaft 16 (the actual valve timing of the intake valve). ) To match the target VCT phase (target valve timing) set according to the engine operating conditions, the control duty (control amount) of the hydraulic control valve 25 is F / B controlled by, for example, PD control, etc., and variable valve timing The hydraulic pressure supplied to the advance chamber 42 and the retard chamber 43 of the device 18 is F / B controlled. Here, “F / B” means “feedback” (hereinafter the same). The control region of the VCT phase control extends over the control region of the retard angle mode R, the holding mode H, and the advance angle mode A. Hereinafter, the F / B control executed when the phase control execution condition is satisfied is referred to as “normal phase control”.

  Further, the engine control circuit 21 also functions as holding control amount learning means in the claims, and when a predetermined holding duty learning execution condition (holding control amount learning execution condition) is satisfied, the hydraulic control valve Based on the control duty of 25, normal holding duty learning for learning a holding duty (holding control amount) necessary to hold the VCT phase constant is executed.

  In this normal holding duty learning, as a holding duty learning execution condition, it is determined whether or not the condition that “the deviation between the target VCT phase and the actual VCT phase is a predetermined value D or less continues for a predetermined time T or longer” is satisfied. When it is determined that the holding duty learning execution condition is satisfied, the control duty of the hydraulic control valve 25 at that time is learned as the holding duty, and the learning value of the holding duty is updated and stored in the memory.

During F / B control of the VCT phase, the control duty of the hydraulic control valve 25 is obtained by adding the F / B correction amount to the hold duty learning value.
Control duty = holding duty learning value + F / B correction amount

  The engine control circuit 21 functions as a lock control means in the claims. When a lock request is generated when the rotation of the engine 11 is stopped or during idle operation, the VCT phase is temporarily intermediated at that time. After performing the pre-lock phase control to move to the pre-lock phase that has passed the lock phase by a predetermined amount, for example, by F / B control such as PD control, the control duty of the hydraulic control valve 25 is set within the control region of the lock mode. Then, while returning the VCT phase toward the intermediate lock phase, lock pin protrusion control is performed to bias the lock pin 58 in the protrusion direction which is the lock direction, and the VCT phase is locked at the intermediate lock phase by the lock pin 58. Control.

  Incidentally, as shown in FIG. 6, when the pre-lock phase control is performed in accordance with the generation of the lock request, if the deviation of the hold duty learning value is large, the VCT phase cannot be accurately controlled to the pre-lock phase. There is a possibility that the VCT phase converges to a position shifted from the pre-lock phase. In such a case, when the holding duty learning value is corrected by performing holding duty learning through normal holding duty learning, the VCT phase can be accurately controlled to the pre-lock phase, and the VCT phase is The pre-lock phase is reached. However, in this case, since the time from when the lock request occurs until the VCT phase reaches the pre-lock phase (execution time of the pre-lock phase control) becomes long, the start timing of the lock pin protrusion control is delayed accordingly, There is a problem that the time until completion (time until the VCT phase is locked with the intermediate lock phase) becomes long.

  As a countermeasure against this, the engine control circuit 21 executes holding duty learning value correction (holding control amount learning value correction) for correcting the holding duty learning value during the pre-lock phase control, and the correction is performed by this holding duty learning value correction. The hydraulic control valve 25 is controlled based on the hold duty learning value.

  Even if the holding duty learning value is shifted when performing the pre-lock phase control with the generation of the lock request, by executing the holding duty learning value correction for correcting the holding duty learning value during the pre-lock phase control, The holding duty learning value can be corrected earlier than the normal holding duty learning, and the hydraulic control valve 25 is controlled based on the holding duty learning value corrected by the holding duty learning value correction. It can be suppressed that the time until the VCT phase reaches the pre-lock phase (execution time of the pre-lock phase control) becomes long.

  During the pre-lock phase control, the accuracy of convergence to the target phase is not required to the same level as during normal phase control, so the holding duty learning accuracy is also not required to be the same level as during normal phase control. Therefore, in the first embodiment, during the pre-lock phase control, priority is given to learning the holding duty earlier than the learning accuracy of the holding duty, and the holding duty learning execution condition (“the target VCT phase and the actual VCT phase The condition that the state where the deviation is equal to or less than the predetermined value D continues for a predetermined time T or more is relaxed, and the holding duty is learned by changing the condition so that the holding duty can be learned earlier than the normal holding duty learning. Holding duty learning value correction for correcting the duty learning value is performed.

  In this case, as a method of relaxing the holding duty learning execution condition, for example, the predetermined value D of the holding duty learning execution condition is made larger than the normal value and the predetermined time T is made shorter than the normal value. Alternatively, only the predetermined value D of the holding duty learning execution condition may be made larger than the normal value, or only the predetermined time T may be made shorter than the normal value. In addition, correction of the holding duty learning value is permitted in the direction in which the VCT phase approaches the pre-locking phase, but correction of the holding duty learning value is prohibited in a direction in which the VCT phase is away from the pre-locking phase.

  By the way, when the holding duty learning value correction is executed even though the holding duty learning value is normal (the state where the deviation of the holding duty learning value is small), the convergence property of the VCT phase to the pre-lock phase deteriorates. There is a possibility.

  Therefore, in the first embodiment, the holding duty learning value correction is executed when the execution time of the pre-lock phase control exceeds a predetermined determination time. That is, when the execution time of the pre-lock phase control is within the determination time, the holding duty learning value may be normal (the deviation of the holding duty learning value is small), so the holding duty learning value correction is not executed. When the execution time of the pre-lock phase control exceeds the determination time (that is, when the VCT phase does not reach the pre-lock phase within the determination time after starting the pre-lock phase control), the holding duty learning value It is determined that the deviation is large, and the holding duty learning value correction is executed.

  In addition, since the holding duty learning value corrected by holding duty learning value correction during the pre-lock phase control may have reduced learning accuracy, if it is reflected in normal phase control as it is, normal phase control There is a possibility that the phase control accuracy will deteriorate.

Therefore, in the first embodiment, the hold duty learning value corrected by the hold duty learning value correction during the pre-lock phase control is not reflected in the normal phase control.
The lock control according to the first embodiment described above is executed by the engine control circuit 21 according to the routines shown in FIGS. Hereinafter, the processing content of each of these routines will be described.

[Lock control routine]
The lock control routine shown in FIG. 7 is repeatedly executed at a predetermined cycle while the engine control circuit 21 is powered on. When this routine is activated, it is first determined in step 101 whether or not a lock request has occurred. If no lock request has occurred, this routine is terminated without performing the subsequent processing.

  Thereafter, when a lock request is generated, the process proceeds from step 101 to step 102 to start the pre-lock phase control. In this pre-lock phase control, the control duty of the hydraulic control valve 25 is F / B controlled by, for example, PD control or the like so that the VCT phase is moved to the pre-lock phase (phase beyond the intermediate lock phase by a predetermined amount). At this time, the control duty of the hydraulic control valve 25 is obtained by adding the F / B correction amount to the hold duty learning value.

  Thereafter, the process proceeds to step 103, where it is determined whether or not the actual VCT phase has reached the pre-lock phase by the pre-lock phase control, and the pre-lock phase control is continued until the actual VCT phase reaches the pre-lock phase.

  Thereafter, when the actual VCT phase reaches the pre-lock phase, the routine proceeds to step 104 where lock pin protrusion control is executed. In this lock pin protrusion control, the control duty of the hydraulic control valve 25 is set in the control region of the lock mode, and the lock pin 58 is attached in the protrusion direction which is the lock direction while returning the VCT phase toward the intermediate lock phase. The VCT phase is locked by the lock pin 58 at the intermediate lock phase.

[Holding duty learning value correction routine]
The hold duty learning value correction routine shown in FIG. 8 is repeatedly executed at a predetermined cycle while the engine control circuit 21 is powered on. When this routine is started, first, at step 201, it is determined whether or not the pre-lock phase control is being performed.

  If it is determined in step 201 that the pre-lock phase control is being performed, the process proceeds to step 202, and the first time after the start of the pre-lock phase control (at the start of the first routine immediately after the start of the pre-lock phase control). If it is determined whether it is the first time after the start of the pre-lock phase control, the process proceeds to step 203, and the current holding duty learning value is stored as the holding duty learning value before correction.

  Thereafter, the process proceeds to step 204, where it is determined whether or not the execution time of the pre-lock phase control has exceeded a predetermined determination value. Here, the determination time is set to a time required for the VCT phase to reach the pre-lock phase when the holding duty learning value is normal (the deviation of the holding duty learning value is small).

  If it is determined in step 204 that the execution time of the pre-lock phase control is within the determination time, the holding duty learning value may be normal (the deviation of the holding duty learning value is small). Then, this routine is terminated without executing the holding duty learning value correction.

  On the other hand, if it is determined in step 204 that the execution time of the pre-lock phase control has exceeded the determination time (that is, the VCT phase has not reached the pre-lock phase within the determination time since the start of the pre-lock phase control). In the case), it is determined that the deviation of the holding duty learning value is large, the process proceeds to step 205, and the holding duty learning value correction is executed as follows. The holding duty learning execution condition (“condition that the deviation between the target VCT phase and the actual VCT phase is equal to or less than the predetermined value D continues for a predetermined time T”) is relaxed, and the holding duty is set earlier than the normal holding duty learning. By changing the learning condition to learn the holding duty, the holding duty learning value correction for correcting the holding duty learning value is performed.

  In this case, as a method of relaxing the holding duty learning execution condition, for example, the predetermined value D of the holding duty learning execution condition is made larger than the normal value and the predetermined time T is made shorter than the normal value. Alternatively, only the predetermined value D of the holding duty learning execution condition may be made larger than the normal value, or only the predetermined time T may be made shorter than the normal value. In addition, correction of the holding duty learning value is permitted in the direction in which the VCT phase approaches the pre-locking phase, but correction of the holding duty learning value is prohibited in a direction in which the VCT phase is away from the pre-locking phase.

  Thereafter, if it is determined in step 201 that the pre-lock phase control is not in progress, the process proceeds to step 206, where it is determined whether the pre-lock phase control has ended, and it is determined that the pre-lock phase control has ended. At this point, the routine proceeds to step 207, where the relaxation of the holding duty learning execution condition is terminated, and both the predetermined value D and the predetermined time T of the holding duty learning execution condition are returned to the normal values.

  Thereafter, the process proceeds to step 208, where it is determined whether or not the lock has been completed by lock pin protrusion control (the VCT phase is locked by the intermediate lock phase). When it is determined that the lock has been completed, the process proceeds to step 209 and held. The holding duty learning value corrected by the duty learning value correction is returned to the holding duty learning value before correction. As a result, the held duty learned value corrected by the held duty learned value correction during the pre-lock phase control is not reflected in the normal phase control.

  Note that when it is determined that the pre-lock phase control has ended, the relaxation of the holding duty learning execution condition may be terminated, and the holding duty learning value may be returned to the holding duty learning value before correction. Alternatively, when it is determined that the lock has been completed, the relaxation of the holding duty learning execution condition may be terminated and the holding duty learning value may be returned to the holding duty learning value before correction.

  An execution example of the hold duty learning value correction of the first embodiment described above will be described with reference to the time chart of FIG. First, the pre-lock phase control is started at time t1 when the lock request is generated. Thereafter, when the execution time of the pre-lock phase control exceeds the determination time (that is, when the VCT phase does not reach the pre-lock phase within the determination time after the start of the pre-lock phase control), the time t2 The holding duty learning value correction corrects the holding duty learning value by relaxing the holding duty learning execution condition and learning the holding duty by changing the condition so that the holding duty can be learned earlier than the normal holding duty learning. I do.

  As a result, the holding duty can be learned earlier than the normal holding duty learning to correct the holding duty learning value, and the hydraulic control valve 25 can be controlled based on the holding duty learning value corrected by the holding duty learning value correction. By controlling the control duty, it is possible to suppress an increase in the time from the time t1 to the time t3 when the VCT phase reaches the pre-lock phase (pre-lock phase control execution time). it can. As a result, it is possible to reduce the delay in the start timing of the lock pin protrusion control, and it is possible to suppress an increase in the time until lock completion (time until the VCT phase is locked with the intermediate lock phase).

  In the first embodiment, when the pre-lock phase control execution time is within the determination time, the holding duty learning value may be normal (the deviation of the holding duty learning value is small). When value correction is not executed but the execution time of the pre-lock phase control exceeds the determination time (that is, when the VCT phase does not reach the pre-lock phase within the determination time after starting the pre-lock phase control). Determines that the deviation of the holding duty learning value is large, and executes the holding duty learning value correction. As a result, it is possible to prevent the holding duty learning value correction from being executed even though the holding duty learning value is normal, and the convergence of the VCT phase to the pre-lock phase is deteriorated by the holding duty learning value correction. Such a situation can be avoided.

  Further, in the first embodiment, at the time when it is determined that the lock is completed (or when it is determined that the pre-lock phase control is completed), the holding duty learning value corrected by the holding duty learning value correction is changed to the value before correction. By returning to the holding duty learning value, the holding duty learning value corrected by the holding duty learning value correction during the pre-lock phase control is not reflected in the normal phase control. It can be prevented that the phase control accuracy of the normal phase control is deteriorated by the holding duty learning value corrected by the learning value correction.

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

  In the second embodiment, the engine control circuit 21 executes a holding duty learning value correction routine of FIG. 10 to be described later, so that the VCT phase approaches the pre-lock phase during the pre-lock phase control as shown in FIG. The holding duty learning value correction for correcting the holding duty learning value is performed by updating the holding duty learning value by a predetermined value every predetermined time.

  The routine of FIG. 10 executed in the second embodiment is obtained by changing the processing of steps 205 and 207 of the routine of FIG. 8 described in the first embodiment to the processing of steps 205a and 207a, respectively. The processing in each step is the same as in FIG.

  In the holding duty learning value correction routine of FIG. 10, first, it is determined whether or not the pre-lock phase control is being performed. If it is determined that the pre-lock phase control is being performed, the first time after the start of the pre-lock phase control is determined. In addition, the current holding duty learning value is stored as the holding duty learning value before correction (steps 201 to 203).

  Thereafter, in step 204, it is determined whether or not the execution time of the pre-lock phase control has exceeded a predetermined determination value. If it is determined that the execution time of the pre-lock phase control has exceeded the determination time (that is, the pre-lock phase If the VCT phase has not reached the pre-lock phase within the determination time after the start of control), it is determined that the deviation of the holding duty learning value is large, and the process proceeds to step 205a, where the holding duty learning value correction is performed. Run as follows: The holding duty learning value correction for correcting the holding duty learning value is performed by updating the holding duty learning value by a predetermined value b every predetermined time a in a direction in which the VCT phase approaches the pre-lock phase.

  In this case, if the current VCT phase is retarded from the pre-lock phase, the hold duty learning value is updated in the advance direction. On the other hand, if the current VCT phase is more advanced than the pre-lock phase, the holding duty learning value is updated in the retard direction. Further, the predetermined time a and the predetermined value b are set to upper limit values within a range where hunting of the VCT phase does not occur due to the update of the hold duty learning value.

  Thereafter, if it is determined in step 201 that the pre-lock phase control is not in progress, the process proceeds to step 206, where it is determined whether the pre-lock phase control has ended, and it is determined that the pre-lock phase control has ended. At this point, the process proceeds to step 207a, and the update of the hold duty learning value is terminated. Thereafter, the process proceeds to step 208, where it is determined whether or not the lock has been completed by lock pin protrusion control (the VCT phase is locked by the intermediate lock phase). When it is determined that the lock has been completed, the process proceeds to step 209 and held. The holding duty learning value corrected by the duty learning value correction is returned to the holding duty learning value before correction. As a result, the held duty learned value corrected by the held duty learned value correction during the pre-lock phase control is not reflected in the normal phase control.

  When it is determined that the pre-lock phase control has ended, the update of the holding duty learning value may be ended and the holding duty learning value may be returned to the holding duty learning value before correction. Alternatively, when it is determined that the lock has been completed, the update of the holding duty learning value may be finished and the holding duty learning value may be returned to the holding duty learning value before correction.

  In the second embodiment described above, as shown in FIG. 11, the holding duty learning value is corrected by updating the holding duty learning value in the direction in which the VCT phase approaches the pre-locking phase during the pre-locking phase control. Since the duty learning value correction is performed, the holding duty learning value correction can be started before the holding duty learning execution condition is satisfied, and the holding duty learning value can be corrected earlier.

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

  In the third embodiment, the engine control circuit 21 executes a lock control routine shown in FIG. 12, which will be described later, and as shown in FIG. By setting the gain larger than the gain, the control duty of the hydraulic control valve 25 when performing the pre-lock phase control is set to a control duty that makes the movement of the VCT phase faster than in the case of normal phase control. Yes.

  The routine of FIG. 12 executed in the third embodiment is obtained by adding the processing of step 102a after step 102 of the routine of FIG. 7 described in the first embodiment. Same as 7.

In the lock control routine of FIG. 12, it is first determined whether or not a lock request has occurred, and pre-lock phase control is started when a lock request has occurred (steps 101 and 102).
Thereafter, the process proceeds to step 102a, where the gain of the pre-lock phase control (for example, the proportional term gain) is set to a gain larger than the gain of the normal phase control, so that the hydraulic control valve 25 for performing the pre-lock phase control The control duty is set to a control duty that makes the VCT phase move faster than in the case of normal phase control.

  Thereafter, it is determined whether or not the actual VCT phase has reached the pre-lock phase by the pre-lock phase control, and the lock pin protrusion control is executed when the actual VCT phase has reached the pre-lock phase (steps 103 and 104). ).

  In the third embodiment described above, as shown in FIG. 13, the pre-lock phase control gain is set by setting the pre-lock phase control gain (for example, proportional term gain) to a gain larger than the normal phase control gain. Since the control duty of the hydraulic control valve 25 at the time of performing is set to a control duty that makes the motion of the VCT phase faster than in the case of normal phase control, the responsiveness of the pre-lock phase control is accelerated and the lock is completed. Time can be shortened.

  In the third embodiment, the pre-lock phase control gain is set to a gain larger than the normal phase control gain. However, the present invention is not limited to this. For example, when the pre-lock phase control is performed, the lock is performed. The previous phase is offset in the direction of accelerating the VCT phase relative to the target phase, or the F / B correction amount of the pre-lock phase control is corrected in a direction that speeds up the responsiveness of the pre-lock phase control. May be.

Next, Embodiment 4 of the present invention will be described with reference to FIG.
In each of the first to third embodiments, the holding duty learning value corrected by the holding duty learning value correction is corrected before the lock is completed (or when the pre-lock phase control is determined to be completed). The holding duty learning value corrected by the holding duty learning value correction during the pre-locking phase control is not reflected in the normal phase control by returning to the holding duty learning value of the first embodiment. As shown in FIG. 14, by setting the holding duty learning value for lock control separately from the normal holding duty learning value, the holding duty learning value corrected by the holding duty learning value correction during the pre-lock phase control is set. It is not reflected in normal phase control.

  As shown in FIG. 14, during normal phase control, the control duty of the hydraulic control valve 25 is set based on the normal hold duty learning value. This normal holding duty learning value is updated by normal holding duty learning executed during normal phase control.

  On the other hand, during the pre-lock phase control, the control duty of the hydraulic control valve 25 is set based on the hold duty learning value for lock control. The holding duty learning value for lock control is set to the same value as the normal holding duty learning value at the time t1 when the pre-lock phase control is started, and thereafter, the holding duty learning value correction executed during the pre-lock phase control is performed. Is corrected and updated. Note that the holding duty learning value for lock control may be returned to the same value as the normal holding duty learning value at the time t3 when the lock is completed (or t2 when the pre-lock phase control ends).

  In the fourth embodiment described above, by setting a holding duty learning value for lock control separately from the normal holding duty learning value, the holding duty corrected by holding duty learning value correction during the pre-lock phase control. Since the learning value is not reflected in the normal phase control, the phase control accuracy of the normal phase control is deteriorated by the holding duty learning value corrected by the holding duty learning value correction during the pre-lock phase control. Can be prevented.

  The present invention is not limited to the first to fourth embodiments described above, and is for a lock control for controlling the hydraulic pressure for controlling the hydraulic pressure for driving the lock pin 58 and the hydraulic control valve for controlling the hydraulic pressure for controlling the hydraulic pressure for driving the VCT phase. It is good also as a structure which provided the hydraulic control valve separately.

  Each of the first to fourth embodiments described above is an embodiment in which the present invention is applied to a variable valve timing device for an intake valve, but may be applied to a variable valve timing device for an exhaust valve. .

  In addition, it goes without saying that the present invention can be implemented with various modifications within a range not departing from the gist, such as appropriately changing the configuration of the variable valve timing device 18 and the configuration of the hydraulic control valve 25.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Crankshaft, 14, 15 ... Sprocket, 16 ... Intake camshaft, 17 ... Exhaust camshaft, 18 ... Variable valve timing device, 19 ... Cam angle sensor, 20 ... Crank angle sensor, DESCRIPTION OF SYMBOLS 21 ... Engine control circuit (VCT phase control means, holding control amount learning means, lock control means), 23 ... Cooling water temperature sensor, 25 ... Hydraulic control valve, 28 ... Oil pump, 31 ... Housing, 35 ... Rotor, 41 ... Vane , 42 ... Advance chamber, 43 ... Delay chamber, 50 ... Intermediate lock mechanism, 58 ... Lock pin, 59 ... Lock hole

Claims (6)

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 position in which the VCT phase is located within the adjustable range. The lock pin that locks with the lock phase, the hydraulic control valve that controls the hydraulic pressure that drives the variable valve timing device and the lock pin, and the VCT phase is held constant when a predetermined hold control amount learning execution condition is satisfied. Holding control amount learning means for performing normal holding control amount learning for learning the holding control amount necessary for performing the control, and controlling the hydraulic control valve based on the learning value of the holding control amount to set the VCT phase. In a variable valve timing control device for an internal combustion engine to be controlled,
When a lock request is generated, the VCT phase is temporarily moved to the pre-lock phase that has passed the intermediate lock phase by a predetermined amount, and then the lock pin is protruded while returning to the intermediate lock phase. Lock control means for performing lock pin protrusion control and controlling the lock pin to lock the VCT phase at the intermediate lock phase;
The lock control means executes a hold control amount learning value correction for correcting the hold control amount learning value during the pre-lock phase control, and the hold control amount learning value corrected by the hold control amount learning value correction. A variable valve timing control device for an internal combustion engine, wherein the hydraulic control valve is controlled based on   The lock control means learns the hold control amount by changing to a condition that allows the hold control amount to be learned earlier than the normal hold control amount learning during the pre-lock phase control. The variable valve timing control apparatus for an internal combustion engine according to claim 1, wherein correction is performed.   The lock control unit performs the holding control amount learning value correction by updating the learning value of the holding control amount in a direction in which a VCT phase approaches the pre-locking phase during the pre-lock phase control. The variable valve timing control device for an internal combustion engine according to claim 1.   4. The lock control unit according to claim 1, wherein the lock control unit performs the holding control amount learning value correction when an execution time of the pre-lock phase control exceeds a predetermined determination time. A variable valve timing control device for an internal combustion engine. VCT phase control means for executing normal phase control for controlling the hydraulic control valve so that the VCT phase coincides with a target VCT phase set according to operating conditions when a predetermined phase control execution condition is satisfied. Prepared,
The lock control means sets the control amount of the hydraulic control valve to a control amount different from that during the normal phase control when performing the pre-lock phase control. A variable valve timing control device for an internal combustion engine according to claim 1. VCT phase control means for executing normal phase control for controlling the hydraulic control valve so that the VCT phase coincides with a target VCT phase set according to operating conditions when a predetermined phase control execution condition is satisfied. Prepared,
6. The lock control device according to claim 1, wherein the learning value of the holding control amount corrected by the holding control amount learning value correction during the pre-locking phase control is not reflected in the normal phase control. The variable valve timing control device for an internal combustion engine according to any one of the above.

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