JP2011226452A - Valve timing control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve timing controller which improves the security of a lock.SOLUTION: The valve timing controller is equipped with a lock mechanism which has a guide groove that guides a lock pin to a lock hole, and it is premised on the assumption that it executes lock control to advance while projecting a lock pin after performing F/B control (lock preparation control) to the opposite side (lag side) of a lock hole to a lock groove, in case that there is a request for lock. The controller is equipped with error determiners S20-S23, which determine whether it is in a large error state where an error in computation of a rotating phase is in a large error state or not, and a corrector S24, which corrects a lock standby phase to the opposite side of the lock phase when determined that it is in a large error state.

Description

  The present invention relates to a valve timing control device applied to a valve timing adjusting device that adjusts the opening / closing timing of an intake valve or an exhaust valve of an engine.

  Conventionally, this type of valve timing adjusting device includes a housing (first rotating body) that rotates together with any one of a cam shaft that drives an intake valve or an exhaust valve to open and close, and an engine output shaft, and the other of the cam shaft and the output shaft. And a vane rotor (second rotating body) rotating together. Further, an advance angle chamber and a retard angle chamber partitioned by vanes of the vane rotor are formed in the housing. Then, by adjusting the pressure of the hydraulic oil supplied to the advance chamber and the retard chamber, control is performed so as to adjust the relative rotation phase of the vane rotor with respect to the housing, thereby adjusting the opening / closing timing of the valve.

  However, since an oil pump that supplies hydraulic oil generally uses engine output as a drive source, hydraulic oil cannot be supplied sufficiently during a period immediately after the start of engine startup. Then, the vane rotor largely fluctuates between the advance side and the retard side due to the torque (fluctuation torque) periodically received by the camshaft from the valve spring of the intake valve or the exhaust valve.

  Therefore, in the conventional apparatus, a lock pin is provided in the vane rotor and a lock hole is provided in the housing. The lock pin is configured to project from the vane rotor housing position to the projecting position when the projecting condition is satisfied, and the lock pin at the projecting position is fitted into the lock hole to lock the vane rotor so as not to be relatively rotatable. Therefore, when the engine is stopped, if the rotation phase is controlled (lock control) so that the lock pin is fitted in the lock hole, the engine is locked at the next engine start, so that the rotation phase greatly fluctuates. This can be avoided (see Patent Documents 1 and 2).

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

  By the way, the lock pin moves toward the lock hole by the lock control described above, but actually, the lock pin moves while swinging between the advance side and the retard side due to receiving the fluctuating torque. . Therefore, when the lock hole (lock phase) is located between the most retarded angle phase and the most advanced angle phase as in Patent Documents 1 and 2, the engine is completely stopped until the operation of the oil pump is stopped. In the meantime, there is a concern that the lock pin cannot be fitted into the lock hole.

  In response to this concern, the inventors examined a lock mechanism having the configuration shown in FIG. That is, a guide groove 63 having a shape extending from the lock hole 59 to the retard side is formed in the housing 31. When the lock pin 58 is fitted into the lock hole 59, first, control is performed to a phase (lock preparation phase) positioned on the retard side with respect to the guide groove 63 as shown by a one-dot chain line in FIG. After that, the lock oil is discharged so that the lock oil is discharged from the hydraulic chamber 57a for releasing the lock and the lock pin 58 is protruded. The lock mechanism has a hardware configuration that advances from the lock preparation phase toward the lock phase when the lock control is performed.

  According to this, the lock pin 58 set at a position on the retard side (lock preparation phase) with respect to the guide groove 63 is first fitted into the guide groove 63 while projecting and then moved within the movement range by the guide groove 63. It moves toward the lock hole 59 while being restricted. Therefore, since the lock pin 58 moves toward the lock hole 59 while swinging is restricted by the guide groove 63, the above-described concern that the lock pin 58 cannot be fitted into the lock hole 59 can be solved.

  However, in the above method of performing the lock control after controlling to the lock preparation phase in this way, if the rotation phase at the present time cannot be accurately calculated prior to the control to the lock preparation phase, Lock control (control to move the lock pin 58 and advance the lock pin 58) is performed from the shifted position. Then, when the lock control is started from a position shifted toward the advance side with respect to the lock preparation phase (position indicated by a two-dot chain line in FIG. 11), the lock pin 58 protrudes until the lock phase is reached. There is a risk that it will not be in time and it will not fit into the lock hole 59 and will advance as it is.

  If the lock preparation phase is set further to the retard side than the position shown by the one-dot chain line in FIG. 11, even if the lock preparation phase is shifted to the advance side with respect to the lock preparation phase, the lock pin is not reached until the lock phase is reached. The possibility that the protrusion of 58 may not be in time can be reduced. However, in this case, the lock pin 58 protrudes before reaching the guide groove 63, and the phase is changed until it reaches the guide groove 63 while the front end surface 58 a of the lock pin 58 is in contact with the housing 31. Therefore, there is a concern about damage to the lock mechanism.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a valve timing control device that improves the certainty of locking.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  According to the first aspect of the present invention, the first rotating body that rotates together with any one of the cam shaft for driving the intake valve or the exhaust valve of the engine to open and close, the output shaft of the engine, and the other of the cam shaft and the output shaft. The first rotation by controlling the hydraulic pressure in the advance chamber and the retard chamber, and a second rotor that forms an advance chamber and a retard chamber with the first rotor. A phase control means for controlling the relative rotational phase of the body and the second rotator, and a lock phase positioned between the most retarded phase and the most advanced angle phase, and the first rotator and the second rotator It is assumed that the present invention is applied to a valve timing adjusting device that includes a lock mechanism that locks the valve in a relatively unrotatable manner.

  The lock mechanism is provided on the second rotating body, and is engaged with the lock pin that protrudes from the housing position to the protruding position by hydraulic pressure, and the lock pin that is formed on the first rotating body and is in the protruding position. A locking hole for locking the first rotating body and the second rotating body in a lock phase so that they cannot be rotated relative to each other, and a groove shape extending from the locking hole to at least one of an advance side and a retard side, and a protruding position And a guide groove that guides the lock pin to the lock hole while limiting the rotational phase within the predetermined limit range by limiting the movement range of the lock pin to a predetermined range. .

  Further, the phase control means includes a phase calculation means for calculating a current rotation phase, and a lock preparation phase in which the rotation phase calculated by the phase calculation means is positioned on the retard side or the advance side with respect to the limit range. A lock preparation control means for controlling the lock pin, and a lock for controlling the lock pin to project and actuate the lock pin while the phase changes from the lock preparation phase to the lock phase side after the control by the lock preparation control means is completed. Control means.

  Then, an error determination unit that determines whether or not the rotation phase calculation error by the phase calculation unit is greater than a predetermined amount is an error large state, and the error determination unit determines that the error is in the large error state Comprises a correction means for correcting the lock preparation phase so as to shift to the opposite side of the lock phase.

  According to the above invention, when the rotational phase calculation error is larger than the predetermined amount, the lock preparation phase is corrected so as to be shifted to the opposite side of the lock phase. Even when the lock control is started from a position shifted to the phase side, it is possible to reduce the concern that the lock pin will not be able to protrude in time until the lock phase is reached. Therefore, the certainty of locking can be improved.

  If the error is not large, the lock preparation phase is not corrected, so that the possibility that the lock pin protrudes before reaching the guide groove during the lock control can be reduced. Therefore, it is possible to reduce the risk of damage to the lock mechanism due to the phase change until the lock pin reaches the guide groove while being brought into contact with the first rotating body.

  According to a second aspect of the present invention, the correction means variably sets the correction amount for correcting the lock preparation phase to be larger as the engine rotational speed is lower or the change amount of the engine rotational speed is larger. And

  Here, when calculating the rotational phase at the present time by the phase calculating means in consideration of the engine rotational speed NE, if the rotational phase is calculated in a state where the NE is largely fluctuated, the calculation error will occur. Becomes bigger. In general, the NE fluctuation increases as the NE decreases. That is, the lower the NE, the larger the NE fluctuation and the larger the rotational phase calculation error.

  According to the above-mentioned invention in view of this point, since the correction amount for the lock preparation phase is variably set to increase as the NE becomes low or the NE fluctuation increases, the lock pin protrudes in time until the lock phase is reached. The fear of disappearing can be further reduced. Therefore, the certainty of locking can be further improved.

  According to a third aspect of the present invention, when it is determined that the error is large during idle operation of the engine, control by the lock preparation control means is performed while performing idle-up control for increasing the engine rotation speed. It is characterized by implementing.

  In the first place, the lock mechanism is intended to be locked during a period in which hydraulic oil at the time of engine start cannot be supplied. Therefore, the lock phase is a phase in which combustion is stabilized at the time of engine start (that is, at low NE). It is usually set to. Therefore, if the lock preparation phase is corrected to the opposite side of the lock phase, combustion becomes unstable, and in some cases, there is a concern that misfire may occur before the lock control is performed.

  In response to this concern, according to the above-described invention, NE is raised by the idle-up control, so that combustion can be stabilized. Therefore, the fear of misfire caused by correcting the lock preparation phase can be reduced.

  In the invention according to claim 4 or 5, when it is determined that the error is large during idle operation of the engine, the engine speed is increased prior to performing the control by the lock preparation control means. The idle-up control is performed.

  As described above, the NE fluctuation increases as the NE decreases, and the rotational phase calculation error increases. This means that if the NE is increased by performing the idle up control, the NE fluctuation is reduced and the calculation error of the rotational phase can be reduced.

  According to the above-mentioned invention in view of this point, after the idle phase-up control is performed, the calculation by the lock preparation control means is performed after the calculation error of the rotation phase is reduced. The actual phase shift with respect to can be reduced. Therefore, the concern that the protrusion of the lock pin may not be in time before the lock phase is reached can be reduced, and the locking reliability can be improved.

  According to a sixth aspect of the present invention, the detection means for detecting the difference between the rotation angle of the output shaft and the rotation angle of the cam shaft, and a reference phase at which the first and second rotating bodies cannot be rotated relative to each other. Learning means for storing the difference when the rotational phase is controlled as a learning value, and the phase calculation means includes the difference detected by the detection means and the learning value stored by the learning means. And the error determination means determines that the error is in a large state when updating of the learning value is not completed.

  When the update of the learning value based on the reference phase is not completed, the calculation error of the rotational phase is highly likely to be large. Therefore, the above-described invention for determining that the error is large when the learning update is not completed. Therefore, the presence or absence of a large error state can be easily determined, which is preferable.

  According to a seventh aspect of the present invention, the error determination means determines that the error is in a large state when the engine rotation speed is less than a predetermined speed or when the change amount of the engine rotation speed is equal to or greater than a predetermined amount. It is characterized by that.

  As described above, since the NE fluctuation increases and the rotational phase calculation error increases as the NE decreases, the above-described invention determines that the error is large when the NE change amount is equal to or greater than a predetermined amount. It is preferable that the presence or absence of a large error state can be easily determined.

1 is a schematic configuration diagram of an entire engine control system according to a first embodiment of the present invention. FIG. 2 is a longitudinal side view for explaining the configuration of a variable valve timing device and a hydraulic control circuit shown in FIG. 1. FIG. 2 is a longitudinal front view for explaining the configuration of the variable valve timing device shown in FIG. 1. Sectional drawing explaining the locking mechanism of the variable valve timing apparatus shown in FIG. FIG. 4 is a control characteristic diagram of a hydraulic control valve for explaining a relationship between four control regions of a lock mode, an advance mode, a hold mode, and a retard mode and a phase change speed. 5 is a flowchart illustrating a lock control procedure in the first embodiment. 5 is a flowchart illustrating a procedure for correcting a lock preparation phase set as a target VCT phase in the first embodiment. The figure explaining that the calculation error of a rotation phase becomes large when NE fluctuation | variation arises. The flowchart which shows the control procedure in 2nd Embodiment of this invention. The flowchart which shows the control procedure in 3rd Embodiment of this invention. The figure which shows the locking mechanism which the present inventors examined in the process which recalls this invention.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used.

(First embodiment)
As shown in FIG. 1, an engine 11 that is an internal combustion engine is configured such that power from a crankshaft 12 (output shaft) receives intake camshaft 16 and exhaust camshaft 17 via a sprocket 14 and 15 by a timing chain 13. To be communicated to. However, the intake side camshaft 16 is provided with a variable valve timing device 18 (VCT) that adjusts the relative rotational phase (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 every predetermined cam angle is installed on the outer peripheral side of the intake side cam shaft 16. On the other hand, on the outer peripheral side of the crank shaft 12, every predetermined crank angle is provided. A crank angle sensor 20 that outputs a crank angle signal pulse is provided. 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 (VCT phase feedback control), and actual valve timing (actual control of the intake valve). The hydraulic pressure for driving the variable valve timing device 18 is feedback controlled so that the (VCT 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.

  As shown in FIG. 2, the housing 31 (first rotating body) of the variable valve timing device 18 is fastened and fixed by bolts 32 to the sprocket 14 that is rotatably supported on the outer periphery of the intake side 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 (second rotating body) is fastened and fixed to one end portion 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 this stopper portion 56 is the latest in the adjustable range of the actual VCT phase. The angular phase and the most advanced angle phase 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 is provided with a lock pin accommodation hole 57 (see FIG. 2), and the housing 31 and the rotor 35 are provided in the lock pin accommodation hole 57. A lock pin 58 for locking relative rotation with the vane 41 is accommodated so as to protrude, and the lock pin 58 protrudes to the sprocket 14 side (right side in FIG. 2) to lock the lock hole 59 (FIG. 2). The VCT phase 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. 2, 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 57a for controlling the hydraulic pressure for driving the lock pin 58 in the unlocking direction is formed.

  When the hydraulic oil is supplied to the hydraulic chamber 57a, the lock pin 58 operates to be accommodated in the accommodation hole 57 against the elastic force of the spring 62 by the hydraulic pressure in the hydraulic chamber 57a. On the other hand, when the hydraulic oil is discharged from the hydraulic chamber 57a, the lock pin 58 protrudes due to the elastic force of the spring 62 and can be fitted into the lock hole 59.

  As shown in FIG. 4, the housing 31 has a guide groove 63 formed in a groove shape extending from the lock hole 59 toward the retarded phase side. The guide groove 63 is formed continuously with the lock hole 59 and is formed shallower than the lock hole 59. As a result, when the lock pin 58 at the protruding position is fitted into the guide groove 63, the movement range of the lock pin 58 is within the range in the guide groove 63 (that is, a predetermined range (limit range) from the lock phase to the retard side). Be restricted. The lock pin 58 shown by the two-dot chain line in FIG. 4 shows a state where the displacement toward the retard side is restricted by the guide groove 63. Therefore, when the lock pin 58 is operated to protrude, the lock pin 58 is guided to the lock hole 59 by the guide groove 63.

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

  In the present embodiment, the range in which the urging force of the spring 55 acts is set in a range from the most retarded angle phase to the almost intermediate lock phase, assuming a fail-safe at the time of restart after an abnormal stop such as an engine stall. When starting with the actual VCT phase retarded from the intermediate lock phase with the lock pin 58 removed from the lock hole 59, the actual VCT is applied by the spring force of the spring 55 during cranking by the starter (not shown). The lock pin 58 is inserted into the lock hole 59 and locked by assisting the advance operation for advancing the phase from the retard side to the intermediate lock phase.

  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, and the lock pin 58 can be fitted into the lock hole 59 to be locked.

  In the present embodiment, the operation of the hydraulic control valve 25 (phase control means) is controlled to control the VCT phase of the variable valve timing device 18 and the hydraulic pressure for driving the lock pin 58. The hydraulic control valve 25 is configured by integrating a hydraulic control valve function for phase control that controls the hydraulic pressure that drives the VCT phase and a hydraulic control valve function for lock control that controls the hydraulic pressure that drives the lock pin 58. Has been.

  The oil (operating oil) in the oil pan 27 is pumped up and supplied to the hydraulic control valve 25 by the oil pump 28 driven by the power of the engine 11. The hydraulic control valve 25 is configured such that the spool 25b is slidably accommodated in the housing 25a, and the spool 25b slides in the housing 25a by electromagnetic force generated by energizing the solenoid 25c from the engine control circuit 21. To do.

  The advance oil passage 42a that communicates with the advance chamber 42, the retard oil passage 43a that communicates with the retard chamber 43, and the lock oil passage 57b that communicates with the unlocking hydraulic chamber 57a communicate with the oil pump 28 via the hydraulic control valve 25. is doing. Then, the sliding position of the spool 25b is controlled according to the control duty (control amount) output from the engine control circuit 21 to the solenoid 25c, whereby the communication opening degree of each oil passage 42a, 43a, 57b is set. Be controlled.

  In the present embodiment, an 8-port, 4-position type spool valve is employed as the hydraulic control valve 25, and the control duty (control amount) for determining the combination of the communication openings of the respective oil passages 42a, 43a, 57b is as follows. As will be described below with reference to FIG. 5, the control mode is divided into four control areas: lock modes L1 and L2, advance angle mode A, hold mode H, and retard angle mode R.

  In the control region of the lock modes L 1 and L 2, the oil supply oil passage 28 a to the unlocking hydraulic chamber 57 a in the lock pin accommodation hole 57 is blocked and the hydraulic pressure in the unlocking hydraulic chamber 57 a in the lock pin accommodation hole 57 is increased. The lock pin 58 is protruded in the locking direction by the spring 62.

  Further, the control region of the lock modes L1 and L2 is the control region of the oil filling mode L1 that supplies the oil to the advance chamber 42 by opening the oil supply oil passage 28a to the advance chamber 42 while protruding the lock pin 58. And the control region of the lock holding mode L2 in which the oil supply oil passages 28a of both the advance chamber 42 and the retard chamber 43 are blocked while the lock pin 58 is projected to hold the oil pressure in the chambers 42, 43. Has been.

  In the control region of the advance angle mode A, the oil supply oil passage 28a 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. Thus, according to the control duty of the hydraulic control valve 25, the oil supply oil passage 28a to the advance chamber 42 is opened, the oil is supplied to the advance chamber 42, and the oil pressure in the advance chamber 42 is changed. Advance the VCT phase.

  In the control region of the holding mode H, the oil supply oil passages 28a of both the advance chamber 42 and the retard chamber 43 are shut off, and the oil pressures in both the chambers 42 and 43 are held so that the actual VCT phase does not move. To do.

  In the control region of the retard angle mode R, the oil supply oil passage 28a 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 of the advance chamber 42 is released. Thus, according to the control duty of the hydraulic control valve 25, the oil supply oil passage 28a to the retard chamber 43 is opened, the oil is supplied to the retard chamber 43, and the hydraulic pressure in the retard chamber 43 is changed. Delay the VCT phase.

  In control areas other than the lock modes L1 and L2 (advance angle mode A, holding mode H, retard angle mode R), the oil supply oil passage 28a to the unlocking hydraulic chamber 57a in the lock pin accommodating hole 57 is opened. The unlocking hydraulic chamber 57a is filled with oil to raise the hydraulic pressure of the unlocking hydraulic chamber 57a, and the lock pin 58 is extracted from the lock hole 59 by the hydraulic pressure to unlock the lock pin 58.

  In this embodiment, as the control duty of the hydraulic control valve 25 increases, the control mode is switched in the order of the lock modes L1 and L2, the advance angle mode A, the holding mode H, and the retard angle mode R. 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 order of the retard angle mode R and the advance angle mode A may be switched, and the control mode may be switched in the order of the lock modes L1, L2, the retard angle mode R, the holding mode H, and the advance angle mode A.

  The engine control circuit 21 (phase control means, feedback control means) determines the actual VCT phase (actual valve timing of the intake valve) of the intake side camshaft 16 when the predetermined phase control execution condition is satisfied. The control duty (control amount) of the hydraulic control valve 25 is subjected to feedback control (F / B control) such as PD control including at least a proportional term so as to coincide with the target phase (target valve timing) set according to the conditions. The hydraulic pressure supplied to the advance chamber 42 and the retard chamber 43 of the variable valve timing device 18 is F / B controlled.

  Thus, the engine control circuit 21 when the target phase is set according to the engine operating condition corresponds to the “target phase control means”, and the engine control circuit 21 when the F / B control is performed is “feedback”. It corresponds to “control means”. 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.

  Next, a control procedure by the hydraulic control valve 25 in the case where the lock pin 58 is fitted into the lock hole 59 and locked in response to the generation of an engine stop request or the like will be described. FIG. 6 is a flowchart showing such a lock control procedure, which is repeatedly executed by the microcomputer of the engine control circuit 21 at a predetermined cycle.

  First, in step S10 shown in FIG. 6, it is determined whether or not a lock request has occurred. For example, a lock request is generated when an automatic engine stop request is generated in an idle stop vehicle or when an ignition switch is turned off. Note that the processing of FIG. 6 controls to complete the lock until the engine rotation speed decreases to zero when the engine stops.

  If it is determined that a lock request has occurred (S10: YES), the process proceeds to the next step S11 (lock preparation control means). Then, as shown by the one-dot chain line in FIG. 4, control is performed so that the lock pin 58 is positioned outside the guide groove 63 and on the retard side (opposite side of the lock hole 59) from the guide groove 63 ( Lock preparation control).

  Specifically, the phase at which the lock pin 58 is positioned at the position of the alternate long and short dash line (hereinafter, this phase is referred to as a lock preparation phase) is set as a target VCT phase and F / B control is performed. For example, if the actual VCT phase at the time of starting the lock preparation control is an advance side of the lock preparation phase, the F / B control is performed in the advance angle mode A until the actual VCT phase becomes the lock preparation phase. On the other hand, if the actual VCT phase at the time of starting the lock preparation control is an advance side of the lock preparation phase, the F / B control is performed in the retard angle mode R until the actual VCT phase becomes the lock preparation phase. It is desirable that the F / B gain at the time of the lock preparation control is made higher than that when the F / B control other than the lock preparation control is performed to increase the phase change speed.

  In the subsequent step S12, it is determined whether or not the actual VCT phase matches the lock preparation phase, and the lock preparation control in step S11 is continued until they match. If it is determined that the actual VCT phase coincides with the lock preparation phase (S12: YES), in the subsequent step S13 (lock control means), lock control is performed in which the actual VCT phase is advanced while the lock pin 58 is protrudingly operated. To do. The advance angle control in this case is open control.

  Specifically, the control duty is decreased to shift from the VCT phase control region (advance angle mode A or retard angle mode R) shown in FIG. 5 to the lock modes L1 and L2. Here, as described above with reference to FIG. 2, the hydraulic control valve 25 is configured by integrating the hydraulic control valve function for phase control and the hydraulic control valve function for lock control. Therefore, it is impossible to continuously shift from the advance angle mode A to the lock holding mode L2, and when the control duty is in the range of Dt to Da in FIG. 5, the advance oil path 42a is communicated to advance the state. It becomes. Even in the lock holding mode, when the control duty is in the range of Da to Db, the advance oil passage 42a is communicated to advance.

  Therefore, when the control duty is decreased to shift from the advance angle mode A to the lock holding mode L2, the lock pin 58 is protruded while the actual VCT phase is advanced. That is, the lock control is executed by reducing the control duty from Dt to Db.

  Here, contrary to the control of FIG. 6, when the F / B control is performed so that the actual VCT phase matches the lock phase without performing the lock preparation control, the lock pin 58 moves toward the lock hole 59. Actually, the rotor 35 moves while swinging between the advance side and the retard side due to the fact that the rotor 35 receives the varying torque from the intake side camshaft 16. Therefore, there is a concern that the lock pin 58 cannot be fitted into the lock hole 59 until the engine is completely stopped and the operation of the oil pump 28 is stopped depending on the swinging condition.

  On the other hand, in the present embodiment, the guide groove 63 for guiding the lock pin 58 to the lock hole 59 is formed, and the lock control is performed after the lock preparation control is performed. Therefore, the lock pin 58 outside the guide groove 63 is formed. Is first fitted in the guide groove 63 when approaching the lock hole 59 by lock control. After that, the guide groove 63 moves toward the lock hole 59 while the movement range is limited. Therefore, since the lock pin 58 moves toward the lock hole 59 while swinging is limited, the above-mentioned concern can be solved.

  However, if the current rotation phase cannot be calculated accurately prior to the lock preparation control, the actual VCT phase will deviate from the lock preparation phase when the F / B control related to the lock preparation control is completed. If this shift occurs on the advance side, the lock pin 58 is advanced to a phase where the lock pin 58 is positioned in the lock hole 59 when the lock pin 58 is protruded and operated while being advanced by the subsequent lock control. In the meantime, the protrusion operation of the lock pin 58 is not in time, and there is a concern that the lock pin 58 may advance further than the lock phase without being locked.

  In response to this concern, in the present embodiment, when the rotational phase calculation error is larger than a predetermined amount, the above-mentioned concern is solved by correcting the lock preparation phase so as to shift to the retard side. ing. The correction control procedure will be described below with reference to FIG. FIG. 7 is a flowchart showing the control procedure of such correction, and is repeatedly executed at a predetermined cycle by the microcomputer included in the engine control circuit 21. 7 is started when a lock request is generated, and is executed until at least the lock preparation control S11 of FIG. 6 is completed.

  First, in each of steps S20, S21, and S22 shown in FIG. 7, it is determined whether or not the situation is a phase error large state. Specifically, first, in step S20, it is determined whether or not learning of a reference phase described below has been completed. If it is determined that learning has not been completed (S20: YES), the phase is determined in subsequent step S23. It is determined that the error is in a large state.

  That is, since the stopper portion 56 is in contact with the housing wall surface 31a when the most advanced angle phase or the most retarded angle phase is controlled, the outputs of the cam angle sensor 19 and the crank angle sensor 20 calculated at this time are used. The detected phase difference (VCT phase) of the signal pulse should be a geometrically specified phase (reference phase). Therefore, if the detected phase difference at this time is learned as the reference phase, when the phase is controlled to be different from the most retarded angle phase and the most retarded angle phase, the difference between the detected phase difference at that time and the reference phase is determined. Based on this, the actual VCT phase can be calculated with high accuracy without including the detection errors of the various sensors 19 and 20. The engine control circuit 21 when learning the reference phase in this way corresponds to “learning means”. This learning is updated every time the ignition switch is turned on.

  In step S21, it is determined whether or not the engine rotation speed is less than a threshold value TH1 (predetermined speed). If it is determined that the engine rotation speed is less than the threshold value TH1 (S21: YES), the phase error is large in the subsequent step S23. It is determined that Further, in step S22, it is determined whether or not the amount of change in engine speed per predetermined time is equal to or greater than a threshold value TH2 (predetermined amount). In step S23, it is determined that the phase error is large. In short, if an affirmative determination is made in any of steps S20, S21, and S22, it is determined that the phase error is large.

  Hereinafter, the reason why the phase calculation error increases when the amount of change in the engine rotation speed is equal to or greater than the threshold value TH2 will be described.

  FIG. 8A shows cam pulses output from the cam angle sensor 19 at every predetermined cam angle (for example, every crank angle 720CA). FIGS. 8B and 8C show changes in the number of counters of crank pulses output from the crank angle sensor 20 every predetermined crank angle (for example, every crank angle 30CA). FIG. 8B shows the change in the NE counter number when the engine speed NE is constant without fluctuation, and FIG. 8C shows the NE when the engine speed NE is fluctuating. Indicates the change in the number of counters.

The current VCT phase is calculated using the following equation (1).
VCT phase (CA) = Tvct (s) × 180 (CA) / T180 (s) (1)
Tvct in the equation (1) is an elapsed time from the cam pulse generation time to the present time (see FIG. 8A). T180 in the equation (1) is the time required for the crankshaft 12 to rotate 180 CA (see FIGS. 8B and 8C). In short, the current VCT phase is calculated by multiplying the elapsed time Tvct from the output of the cam pulse to the current time by the average rotational speed (180 (CA) / T180 (s)) of the crankshaft 12. The engine control circuit 21 when calculating the VCT phase in this way corresponds to “phase calculation means”.

  Therefore, when the NE fluctuation occurs as shown in FIG. 8C, the average rotational speed used for the calculation of Expression (1) is different from the actual rotational speed during the period of Tvct. A calculation error occurs in the VCT phase calculated using 1).

  As described above, the calculation error of the VCT phase becomes large when the NE fluctuation is large (when the change amount ≧ TH2). Further, since the NE fluctuation increases as the engine speed NE decreases, the calculation error of the VCT phase increases.

  If it is determined in steps S20 to S23 (error determination means) that the phase error is in the large state, in the subsequent step S24 (correction means), the lock preparation phase is corrected to be shifted by a predetermined amount toward the advance side. . On the other hand, if a negative determination is made in any of steps S20 to S22, the process of FIG. 7 is terminated without performing the correction in step S24.

  As described above, according to the present embodiment, when the error in calculating the VCT phase is larger than a predetermined amount, the lock preparation phase is corrected to shift to the opposite side (retard side) of the lock phase. Therefore, even when the lock control is started from a position shifted to the lock phase side (advance side) with respect to the lock preparation phase, it is possible to reduce a concern that the protrusion of the lock pin 58 is not in time until the lock phase is reached. . Therefore, the certainty of locking can be improved.

  If the error is not large, the lock preparation phase is not corrected, so that the possibility that the lock pin 58 protrudes before reaching the guide groove 63 during the lock control can be reduced. Therefore, it is possible to reduce the risk of damage to the lock mechanism due to the phase change until the lock groove 58 reaches the guide groove 63 while abutting the tip surface of the lock pin 58 against the housing 31.

(Second Embodiment)
In the present embodiment, the processing of FIG. 6 in the first embodiment is changed as shown in FIG. FIG. 9 is a flowchart showing a lock control procedure according to the present embodiment, and the processing procedure of FIG. 9 will be described below.

  First, in step S30 in FIG. 9, it is determined whether or not a lock request has occurred in the same manner as in step S10 in FIG. If it is determined that a lock request has occurred (S30: YES), in the subsequent step S31, it is determined whether or not the rotational phase calculation error is in a large error state greater than a predetermined amount. This determination method is the same as steps S20 to S23 in FIG. When it is determined that the error is in a large state (S31: YES), in the subsequent step S32 (idle-up control means), the idling control is performed so that the engine speed NE becomes a predetermined idle speed. Idle-up control is started such that idle control is performed by increasing a predetermined idle rotation speed by a predetermined amount.

  In subsequent steps S33, S34, and S35, lock preparation control and lock control are performed in the same manner as in steps S11, S12, and S13 of FIG. In short, in the present embodiment, when it is determined that the error is large during the idling operation of the engine, the idle up control for increasing the engine rotation speed is performed, and then the lock preparation control is performed. Further, the lock control is performed in the idle-up state.

  In the first place, the lock phase is set to a phase in which combustion is stable when the engine is started (that is, at low NE). Therefore, if the lock preparation phase is corrected to the retard side by the process of FIG. 7, there is a concern that the combustion becomes unstable and in some cases misfires before the lock control is performed. With respect to this concern, according to the present embodiment, the engine speed is increased by the idle-up control, so that combustion can be stabilized. Therefore, the fear of misfire caused by correcting the lock preparation phase can be reduced.

  In addition, according to the present embodiment, the lock preparation control is performed after the start of the idle up control. Therefore, after the VCT phase calculation error is reduced, the lock preparation control is performed. It is possible to improve the accuracy of the lock preparation phase by the F / B control related to the control. Therefore, it is possible to reduce the concern that the protrusion of the lock pin 58 will not be in time before the lock phase is reached when performing the lock control, and the locking reliability can be improved.

(Third embodiment)
In the present embodiment, the processing of FIG. 7 in the first embodiment is changed as shown in FIG. FIG. 10 is a flowchart showing a procedure for correcting the lock preparation phase according to the present embodiment. Hereinafter, the processing procedure of FIG. 10 will be described.

  First, in step S40 (error determination means) in FIG. 10, it is determined whether or not the learning of the reference phase has been completed in the same manner as in step S20 in FIG. If learning is not completed, the process proceeds to step S41, where it is determined that the phase error is large, and a correction amount A for the lock preparation phase is calculated. This correction amount A is a fixed value set in advance.

  Next, in step S42 (error determination means), it is determined whether or not the engine speed is less than the threshold value TH1 in the same manner as in step S21 of FIG. If it is determined that the threshold value is less than TH1, the process proceeds to step S43, where it is determined that the phase error is large, and a correction amount B for the lock preparation phase is calculated. This correction amount B is variably set so as to increase as the engine speed decreases.

  Next, in step S44 (error determination means), it is determined whether or not the amount of change in the engine rotation speed is equal to or greater than the threshold value TH2 as in step S22 of FIG. If it is determined that the threshold value is greater than or equal to the threshold TH2, the process proceeds to step S45, where it is determined that the phase error is large, and a correction amount C for the lock preparation phase is calculated. This correction amount C is variably set so as to increase as the amount of change in engine speed increases.

  In the following step S46, the correction amount (A + B + C) is calculated by adding the correction amounts calculated in steps S41, S43, and S45. In the next step S47 (correction means), the lock preparation phase is shifted to the retard side by the correction amount (A + B + C) calculated in step S46. In short, in this embodiment, the correction amount is calculated for each factor of the large phase error state. Further, the correction amount is variably set so as to increase as the engine speed decreases and as the change amount of the engine speed increases.

  Here, the lower the engine rotational speed, the larger the fluctuation of the engine rotational speed, and the larger the fluctuation, the larger the calculation error of the VCT phase should be. Therefore, according to the present embodiment, when performing the lock control, it is possible to further reduce the concern that the protrusion of the lock pin 58 may not be in time before the lock phase is reached.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows. In addition, the characteristic configurations of the respective embodiments may be arbitrarily combined.

  When the actual VCT phase at the time when the lock request is generated is positioned on the more retarded side than the lock preparation phase, the lock control according to step S13 is performed without performing the lock preparation control according to step S11 in FIG. May be implemented.

  In the second embodiment, idle-up control is performed when the error is large. However, when this idle-up control is performed, the correction shown in FIGS. 7 and 10 may not be performed.

  In the above embodiment, the present invention is applied to the VCT attached to the intake side camshaft 16, but the present invention may be applied to the VCT attached to the exhaust side camshaft 17.

  In the above embodiment, the shape of the guide groove 63 is formed so as to extend only from the lock hole 59 to the retard side as shown in FIG. 4, but the shape extends to both the retard side and the advance side. It may be formed.

  In the above embodiment, the lock preparation phase is set to the retard side of the lock phase, but the lock preparation phase is set to the advance side of the lock phase and the guide groove 63 is at least advanced from the lock hole 59. You may make it form in the shape extended to the side. The lock mechanism in this case may be of a hardware configuration in which the actual VCT phase is retarded to the lock phase side when lock control for projecting the lock pin 58 is performed.

  DESCRIPTION OF SYMBOLS 12 ... Crankshaft (output shaft), 16 ... Intake side camshaft, 17 ... Exhaust side camshaft, 21 ... Engine control circuit (phase calculation means, learning means, detection means), 31 ... Housing (1st rotary body), 35 ... Rotor (second rotating body), 50 ... Intermediate lock mechanism (lock mechanism), 58 ... Lock pin, 59 ... Lock hole, 63 ... Guide groove, S11 ... Lock preparation control means, S13 ... Lock control means, S20 ~ S23, S40, S42, S44 ... error determination means, S24, S47 ... correction means, S32 ... idle-up control means.

Claims (7)

A camshaft that opens and closes an intake valve or an exhaust valve of the engine, and a first rotating body that rotates together with any one of the output shaft of the engine;
A second rotating body that rotates together with the other of the cam shaft and the output shaft and forms an advance chamber and a retard chamber with the first rotating body;
Phase control means for controlling the relative rotational phase of the first rotating body and the second rotating body by controlling the hydraulic pressure in the advance chamber and the retard chamber;
A locking mechanism that locks the first rotating body and the second rotating body in a relatively non-rotatable manner with a lock phase positioned between the most retarded angle phase and the most advanced angle phase;
Applied to a valve timing adjustment device comprising:
The locking mechanism is
A lock pin that is provided on the second rotating body and that is operated to protrude from a storage position to a protruding position by hydraulic pressure;
A lock hole formed in the first rotating body and locking the first rotating body and the second rotating body in a lock phase so as not to be relatively rotatable by fitting with the lock pin in a protruding position;
By forming the groove shape extending from the lock hole to at least one of the advance side and the retard side, and restricting the movement range of the lock pin at the protruding position to a predetermined range, the rotational phase is within the predetermined limit range. A guide groove for guiding the lock pin to the lock hole while restricting;
Is configured with
The phase control means includes
A phase calculating means for calculating the current rotational phase;
Lock preparation control means for controlling the rotation phase calculated by the phase calculation means to be a lock preparation phase located on the retard side or advance side with respect to the limit range;
After the control by the lock preparation control means is completed, the lock control means for controlling the lock so as to change the phase from the lock preparation phase to the lock phase and to project the lock pin.
Have
An error determination means for determining whether or not the rotation phase calculation error by the phase calculation means is a large error state greater than a predetermined amount;
When the error determination unit determines that the error is in the large error state, a correction unit that corrects the lock preparation phase to shift to the opposite side of the lock phase;
A valve timing control device comprising:   The said correction | amendment means variably sets so that the correction amount which correct | amends the said lock preparation phase may be enlarged, so that the engine rotation speed is low or the variation | change_quantity of engine rotation speed is large. Valve timing control device.   When it is determined that the error is in the large state during the idle operation of the engine, the lock preparation control means performs the control while performing the idle up control for increasing the engine rotation speed. The valve timing control device according to claim 1 or 2.   If it is determined that the error is in a large state during the idling operation of the engine, idle up control for increasing the engine rotation speed is performed prior to performing the control by the lock preparation control means. The valve timing control device according to any one of claims 1 to 3. A camshaft that opens and closes an intake valve or an exhaust valve of the engine, and a first rotating body that rotates together with any one of the output shaft of the engine;
A second rotating body that rotates together with the other of the cam shaft and the output shaft and forms an advance chamber and a retard chamber with the first rotating body;
Phase control means for controlling the relative rotational phase of the first rotating body and the second rotating body by controlling the hydraulic pressure in the advance chamber and the retard chamber;
A locking mechanism that locks the first rotating body and the second rotating body in a relatively non-rotatable manner with a lock phase positioned between the most retarded angle phase and the most advanced angle phase;
Applied to a valve timing adjustment device comprising:
The locking mechanism is
A lock pin that is provided on the second rotating body and that is operated to protrude from a storage position to a protruding position by hydraulic pressure;
A lock hole formed in the first rotating body and locking the first rotating body and the second rotating body in a lock phase so as not to be relatively rotatable by fitting with the lock pin in a protruding position;
By forming the groove shape extending from the lock hole to at least one of the advance side and the retard side, and restricting the movement range of the lock pin at the protruding position to a predetermined range, the rotational phase is within the predetermined limit range. A guide groove for guiding the lock pin to the lock hole while restricting;
Is configured with
The phase control means includes
A phase calculating means for calculating the current rotational phase;
Lock preparation control means for controlling the rotation phase calculated by the phase calculation means to be a lock preparation phase located on the retard side or advance side with respect to the limit range;
After the control by the lock preparation control means is completed, the lock control means for controlling the lock so as to change the phase from the lock preparation phase to the lock phase and to project the lock pin.
Have
An error determination means for determining whether or not the rotation phase calculation error by the phase calculation means is a large error state greater than a predetermined amount;
If it is determined that the error is in the large state during the idling operation of the engine, the idling up control for performing the idling up control for increasing the engine rotation speed prior to performing the control by the lock preparation control means. Means,
A valve timing control device comprising: Detecting means for detecting a difference between a rotation angle of the output shaft and a rotation angle of the cam shaft;
Learning means for storing the difference as a learning value when the rotation phase is controlled to a reference phase at which the first rotation body and the second rotation body are not relatively rotatable;
With
The phase calculating means calculates a rotational phase based on the difference detected by the detecting means and the learning value stored by the learning means;
The valve timing control device according to claim 1, wherein the error determination unit determines that the error is in a large state when the update of the learning value is not completed.   2. The error determination means determines that the error is in a large state when the engine rotation speed is less than a predetermined speed or when the change amount of the engine rotation speed is a predetermined amount or more. The valve timing control apparatus as described in any one of -6.

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