JP2012036963A - Control device of hydraulic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a hydraulic actuator, which can preferably prevent the deterioration of controllability at low oil temperature as a result of learning a holding control amount at high oil temperature.SOLUTION: There is provided the control device of the hydraulic actuator, which performs feedback control of a phase so as to converge an actual phase to a target phase and learns a duty command value where variation speed of the phase is "0" as the holding control amount. An electronic control unit 17 specifies a range of a dead zone of the duty command value in which a variation of the variation speed of the phase relative to the variation of the duty command value is small and controls the holding control amount so that the value is maintained in the specified range of the dead zone.

Description

  The present invention relates to a control device for a hydraulic actuator that performs phase feedback control to converge an actual phase to a target phase, and learns a control command value at which the phase change speed is “0” as a holding control amount.

  As is well known, a variable valve timing mechanism has been put to practical use as a mechanism mounted on an internal combustion engine such as a vehicle. The variable valve timing mechanism uses a hydraulic actuator as means for changing the rotational phase of the camshaft.

  The hydraulic actuator includes two oil chambers, that is, an advance oil chamber and a retard oil chamber. The valve timing is advanced by the supply of pressurized oil to the advance oil chamber and the discharge of pressurized oil from the retard oil chamber, the supply of pressurized oil to the retard oil chamber, and the advance oil chamber from the advance oil chamber. The valve timing is retarded by discharging the pressurized oil.

  Supply and discharge of pressurized oil to and from both oil chambers to the hydraulic actuator are controlled by an oil control valve (OCV). The OCV is formed by an advance port connected to the advance oil chamber, a retard port connected to the retard oil chamber, a drain port connected to the oil tank, and a supply port connected to the hydraulic pump. Provided with a sleeve. The OCV also includes a spool that is slidably disposed within the sleeve. Then, by changing the operating position of the spool in the sleeve, the supply and discharge of the pressurized oil to and from each oil chamber is controlled to change or hold the valve timing. The spool is driven by a solenoid, and the operating position of the spool in the sleeve is controlled by changing the duty of the solenoid supply current between 0 and 100%.

  When the spool is in the neutral region in the sleeve, the advance port and retard port do not communicate with either the supply port or the drain port, and the supply and discharge of pressurized oil to both oil chambers are substantially blocked. Become. On the other hand, when the spool is displaced in one direction (advance direction) from the neutral region, the advance oil chamber is communicated with the supply port, and the retard port is communicated with the drain port. The pressurized oil is supplied to the tank and the pressurized oil is discharged from the retard oil chamber (advance angle mode). Also, if the spool is displaced from the neutral zone in the direction opposite to the advance direction (retard direction), the retard oil chamber communicates with the supply port, and the advance port communicates with the drain port. Supply of pressurized oil to the corner oil chamber and discharge of pressurized oil from the advance oil chamber are performed (retard angle mode).

  In OCV duty control, the duty command value is successively updated so that the phase (actual phase) of the hydraulic actuator obtained from the detection signal of the cam angle sensor converges to the target phase according to the operating state of the internal combustion engine. Feedback control is performed. During such phase feedback control, holding control amount learning control is performed.

  The holding control amount learning control is a control in which a duty command value at which the phase change speed of the hydraulic actuator is “0” is specified and the value is learned as a holding control amount. For example, when the target phase has not changed over a certain time and the actual phase has not changed over a certain time, the duty command value of the OCV at that time is stored and updated as a holding control amount. Holding control amount learning control is performed.

  By the way, when the hydraulic oil of the hydraulic actuator becomes high temperature, the viscosity decreases, and the amount of oil leaking through the clearance of each part of the OCV and the hydraulic actuator increases. For this reason, when the oil temperature is high, the oil pressure in both oil chambers may drop, and the actual phase of the hydraulic actuator may fluctuate near the target phase. If holding control amount learning control is performed in such a state, an inappropriate value may be set for the holding control amount.

  Therefore, conventionally, a technique described in Patent Document 1 has been proposed as a technique for preventing such erroneous learning of the holding control amount at a high oil temperature. In the technique described in this document, the retention control amount learning control is prohibited at high oil temperature to prevent erroneous learning and to ensure the stability of the valve timing control.

JP 2007-224744 A

  By the way, the hydraulic actuator is always urged in the retarded direction due to the friction of the cam journal, etc., and in order to maintain the phase, the hydraulic pressure of the advanced oil chamber is set higher than the hydraulic pressure of the retarded oil chamber. It is necessary to make it slightly higher so as to counter such urging force in the retarded direction. That is, in order to maintain the phase, the hydraulic actuator needs to be set to a weak advance angle mode in which a force based on the oil pressure is slightly applied in the advance angle direction.

  On the other hand, at the time of high oil temperature at which oil viscosity decreases and oil leakage increases, the hydraulic pressure of the pressurized oil supplied to the oil chamber is low even if the duty command value is the same. Therefore, when the oil temperature is high, the duty command value necessary for maintaining the phase becomes a value on the advance side, and thus the holding control amount changes to the value on the advance side. Therefore, if the hold control amount learned at high oil temperature is used at a lower oil temperature than at the time of learning, the feedback control of the hydraulic actuator will be unstable, such as the actual phase overshooting the target phase. It comes to become.

  If the holding duty learning at the time of high oil temperature is prohibited as in the above-described conventional technology, such instability of control can be alleviated to some extent. However, if the learning of the holding duty command value at high oil temperature is completely prohibited, the duty command value necessary for maintaining the phase at high oil temperature becomes unknown, so the holding controllability at high oil temperature is not possible. It will get worse.

  The present invention has been made in view of such circumstances, and the problem to be solved is to suitably prevent deterioration of controllability at low oil temperature as a result of learning of the hold control amount at high oil temperature. It is an object of the present invention to provide a control device for a hydraulic actuator that can be used.

  In order to solve the above-mentioned problem, the invention according to claim 1 performs the feedback control of the phase so as to converge the actual phase to the target phase, and holds the control command value at which the phase change speed becomes “0”. The premise is a control device for a hydraulic actuator that learns as follows.

  In such a hydraulic actuator control device, the oil pressure applied to the hydraulic actuator decreases at the same control command value at a high oil temperature when the oil viscosity is low and oil leakage increases. For this reason, the control command value that can ensure the oil pressure necessary to maintain the phase changes according to the oil temperature, and the phase control is performed at the low oil temperature using the holding control amount learned at the high oil temperature. For example, the hold controllability may deteriorate and phase overshoot may occur.

  In that respect, in the first aspect of the invention, the specifying means for specifying the dead zone range of the control command value in which the change in the phase change speed with respect to the change in the control command value is smaller than the predetermined value, and the holding control amount are specified. Limiting means for limiting within the range of the dead zone. Therefore, the value of the holding control amount is held within the dead zone of the control command value regardless of how much the oil temperature changes. Therefore, according to the first aspect of the present invention, it is possible to suitably prevent the controllability from deteriorating at low oil temperature as a result of learning the holding control amount at high oil temperature. By the way, even if this restriction of holding control amount is implemented during feedback control, since the holding control amount is continuously updated within the dead zone, the holding controllability under high oil temperature should be secured to some extent. Is possible.

  By the way, if the hold control amount is limited within the dead zone under the feedback control at high oil temperature, the duty command value required to hold the phase at that time and the hold control amount will deviate, resulting in a high oil temperature. The holding controllability below may deteriorate. Therefore, if it is desired to ensure the retention controllability under a high oil temperature, the processing relating to the restriction is performed after the feedback control is completed as described in claim 2, or the feedback is performed as described in claim 3. The limiting means may be configured to perform processing related to the limitation before the start of control. In this case, under the feedback control at the time of the high oil temperature, the update of the holding control amount that is left to the event is allowed, and the holding control amount is limited as described above after the feedback control is completed. For this reason, it is possible to prevent deterioration in controllability at low oil temperatures as a result of learning the retention control amount at high oil temperatures while ensuring retention controllability at high oil temperatures.

  In addition, such a control device for a hydraulic actuator of the present invention comprises two oil chambers, an advance oil chamber and a retard oil chamber, according to claim 4, and the engine valve of the engine valve is supplied and discharged through the hydraulic oil in both oil chambers. It can be applied to a hydraulic actuator with variable valve timing. In such a case, when the hydraulic actuator is configured to hold the phase in a state where the hydraulic pressure of the advance oil chamber is higher than the hydraulic pressure of the retard oil chamber, as in claim 5 In addition, the limit control unit is configured to limit the hold control amount so that it becomes a value on the retard side rather than the limit value on the advance side of the dead zone, so that the result of learning the hold control amount at high oil temperature It is possible to suitably prevent the controllability from deteriorating at a low oil temperature.

The block diagram which shows typically the whole structure about one Embodiment of this invention. The graph which shows the relationship between the duty command value and phase change speed of the hydraulic actuator to which the embodiment is applied. The flowchart which shows the process sequence of the holding | maintenance control amount setting routine applied to the embodiment.

  Hereinafter, an embodiment of a hydraulic actuator control apparatus according to the present invention will be described in detail with reference to FIGS. In this embodiment, the hydraulic actuator is provided with two oil chambers, an advance oil chamber and a retard oil chamber, and the valve timing of the engine valve is variable through supply / discharge of hydraulic oil in both oil chambers. The control device is applied.

  FIG. 1 shows the overall configuration of the present embodiment. As shown in the figure, the hydraulic valve timing mechanism of the internal combustion engine to which the present embodiment is applied includes a hydraulic pump 12 that pressurizes and discharges oil, and a hydraulic actuator 1 that operates according to the supply of hydraulic pressure. An oil control valve (OCV) 6 is provided for changing the supply mode of the hydraulic pressure to the hydraulic actuator 1.

The hydraulic pump 12 is driven by rotation of a crankshaft that is an engine output shaft, and pumps out oil from the oil tank 11 and pressurizes and discharges the oil.
The hydraulic actuator 1 includes a vane rotor 2 connected to a camshaft of an internal combustion engine so as to be integrally rotatable, and a housing 3 connected to a cam sprocket so as to be integrally rotatable. The cam sprocket is drivingly connected to the crankshaft of the internal combustion engine via a timing chain.

  The vane rotor 2 formed in a substantially cylindrical shape is formed with a plurality (two in the figure) of vanes protruding in the radial direction from the outer periphery thereof. And each vane is each accommodated in the recessed part extended in the circumferential direction formed in the inner periphery of the housing 3 formed in the substantially annular shape.

  A recess in the inner periphery of the housing 3 is partitioned into two oil chambers by vanes. Among these, the oil chamber formed in the counter-rotating direction of the camshaft with respect to the vane is an advance oil chamber 4 into which hydraulic pressure for urging the vane in the rotating direction of the camshaft is introduced. The oil chamber is a retarded oil chamber 5 into which hydraulic pressure is applied to urge the vane in the counter-rotating direction of the camshaft.

  On the other hand, the OCV 6 includes a circular sleeve 7 and a spool 8 slidably disposed in the sleeve 7. The spool 8 is disposed in the sleeve 7 with one end supported by the solenoid 9 and the other end supported by the spring 10.

  The sleeve 7 of the OCV 6 has four ports, a supply port S, a drain port D, an advance port A, and a retard port R, so that the communication mode of each port changes depending on the operating position of the spool 8. It has become. Here, a hydraulic pump 12 is connected to the supply port S via a supply oil passage 13, and a drain oil passage 14 used for discharging oil to the oil tank 11 is connected to the drain port D. The advance port A is connected to an advance oil passage 15 communicated with the advance oil chamber 4 of the hydraulic actuator 1, and the retard port R is communicated with the retard oil chamber 5 of the hydraulic actuator 1. A retard oil passage 16 is connected.

  Here, when the spool 8 is located in the neutral range, both the advance port A and the retard port R are not connected to either the supply port S or the drain port D, and the advance oil chamber 4, the retard port Supply and discharge of pressurized oil to both of the oil chambers 5 are blocked. Strictly speaking, some oil is supplied to the advance oil chamber 4 and the retard oil chamber 5 at this time, and the oil leaked through the clearance of each part of the hydraulic actuator 1 is advanced oil. The chamber 4 and the retarded oil chamber 5 are supplemented.

  Here, when the spool 8 is displaced in the right direction (advance direction) in the figure beyond the neutral range, the advance port A is connected to the supply port S and the retard port R is connected to the drain port D. The pressurized oil is supplied to the corner oil chamber 4 and the pressurized oil is discharged from the retarded oil chamber 5 (advance angle mode). When the spool 8 is displaced in the left direction (retard direction) in the figure beyond the neutral range, the retard port R is connected to the supply port S and the advance port A is connected to the drain port D. The pressurized oil is discharged from the oil chamber 4 and the pressurized oil is supplied to the retarded oil chamber 5 (retarded mode).

  The spool 8 of the OCV 6 is driven through duty control of the current supplied to the solenoid 9. Such duty control of the supply current of the solenoid 9 is executed by the electronic control unit 17. The electronic control unit 17 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output port (I / O). Here, the CPU executes various arithmetic processes related to duty control of the supply current of the solenoid 9, and the ROM stores a control program and data. The RAM temporarily stores the calculation results of the CPU, the detection results of the sensors, and the like, and the I / O functions as an interface that mediates input / output of signals to the outside.

  The input port of the electronic control unit 17 includes an oil temperature sensor 18 that detects the temperature of oil discharged from the hydraulic pump 12, a crank angle sensor 19 that detects the phase of the crankshaft, and a cam angle that detects the phase of the camshaft. A detection signal from the sensor 20 or the like is input. The electronic control unit 17 calculates the current valve timing of the engine valve from the detection results of the crank angle sensor 19 and the cam angle sensor 20.

  In this embodiment, as described above, the electronic control unit 17 performs duty control on the supply current of the solenoid 9 of the OCV 6. Then, the spool 8 of the OCV 6 is driven to change the supply / discharge mode of the pressurized oil in the advance oil chamber 4 and the retard oil chamber 5, thereby driving the hydraulic actuator 1, and the valve of the engine valve. The timing is changed.

  The electronic control unit 17 performs phase feedback control in almost all periods except when the engine is started and when the engine is stopped when the phase of the hydraulic actuator 1 is held at the most retarded angle. This feedback control is performed by adjusting the duty command value so that the actual phase calculated from the detection signal of the cam angle sensor 20 and the like converges to the target phase set according to the engine operating state.

  FIG. 2 shows the relationship between the duty command value (control command value) for the solenoid 9 of the OCV 6 and the phase change speed of the hydraulic actuator 1. As shown in the figure, the response of the hydraulic actuator 1 to the change of the duty command value, that is, the change of the displacement speed, before and after the holding control amount at which the phase change speed becomes “0”. There is a dead band smaller than the default value. In this figure, the range of the duty command value from the lower limit value D1 to the upper limit value D2 is such a dead zone. On the other hand, when the duty command value increases beyond the upper limit value D2 of the dead zone, the displacement speed of the hydraulic actuator 1 in the advance direction increases linearly as the duty command value increases. Further, when the duty command value decreases beyond the lower limit D1 of the dead zone, the displacement speed of the hydraulic actuator 1 in the retarding direction increases linearly with a decrease in the duty command value.

  In the present embodiment, the electronic control unit 17 specifies the lower limit value D1 and the upper limit value D2 of the dead zone through learning. In this learning, the absolute value of the phase change speed of the hydraulic actuator 1 is calculated, and the previous value is smaller than the predetermined reference value, but the duty command value when the current value is larger than the reference value is set to the dead band. This is performed by learning as the lower limit value D1 or the upper limit value D2.

  In the present embodiment, holding control amount learning control is performed in which the duty command value at which the phase change rate of the hydraulic actuator 1 is “0” is specified and the value is learned as the holding control amount. . In this holding control amount learning control, for example, when the target phase has not changed over a certain time and the actual phase has not changed over a certain time, the OCV duty command value at that time is held and controlled. This is done by storing and updating as a quantity.

  Note that the hydraulic actuator 1 to which the present embodiment is applied is always urged in the retarded direction by friction or the like in the cam journal, and in order to maintain the phase, the hydraulic pressure in the advanced oil chamber 4 is maintained. Needs to be slightly higher than the hydraulic pressure of the retarded oil chamber 5 to counteract the urging force in the retarded direction. That is, in order to maintain the phase, the hydraulic actuator 1 needs to be in a weak advance angle mode in which a force based on the oil pressure is slightly applied in the advance angle direction.

  On the other hand, when the oil temperature increases and the oil viscosity decreases, oil leakage through the clearance of each part of the OCV 6 and the hydraulic actuator 1 increases, and the hydraulic pressure applied to the hydraulic actuator 1 at the same duty command value decreases. become. Therefore, when the oil temperature is high, the relationship between the duty command value and the phase change speed is shifted to the right in the figure as a whole as shown by the broken line in the figure. The duty command value necessary for maintaining the phase becomes a value on the advance side when the oil temperature is high and the value on the advance side compared to the value when the oil temperature is low. Therefore, if phase control is performed using a holding control amount learned at a high oil temperature at a low oil temperature, the holding controllability may deteriorate and phase overshoot may occur.

  Therefore, in the present embodiment, the range of the dead zone in which the change in the actual phase with respect to the change in the duty command value is smaller than the predetermined value is specified, and the holding control amount is set so that the value is maintained within the specified dead zone range. I try to limit it. More specifically, the holding control amount is limited so as to be a value on the retard side of the upper limit value D2 that is the limit value on the advance side of the dead zone. For this reason, in the present embodiment, the value of the hold control amount is held within the dead zone of the control command value regardless of how much the oil temperature changes. Therefore, according to the present embodiment, it is possible to suitably prevent the controllability from deteriorating at low oil temperature as a result of learning the holding control amount at high oil temperature.

  However, if the holding control amount is limited to less than the upper limit D2 of the dead zone under feedback control at high oil temperature, the holding control amount becomes smaller than the duty command value necessary for holding the phase at that time, and high oil The holding controllability under temperature deteriorates. Therefore, in the present embodiment, under the feedback control at the time of high oil temperature, it is allowed to update the holding control amount depending on the course, and after the feedback control is finished, the holding control amount is limited as described above. ing.

  FIG. 3 shows a flowchart of a holding control amount setting routine applied to the present embodiment. The processing of this routine is repeatedly executed at regular control cycles by the electronic control unit 17 during engine operation.

  When this routine is started, it is first determined in step S100 whether or not the hydraulic actuator 1 is in the phase feedback control mode (F / B mode). In the present embodiment, the hydraulic actuator 1 is basically controlled in the F / B mode during most of the period except when the engine is started and when the engine is stopped.

  If it is in the F / B mode here (S100: YES), it is determined in step S101 whether or not a holding control amount update condition is satisfied. If the update condition is satisfied (S101: YES), the holding control amount is updated in step S102. If not (S101: NO), the process of this routine is terminated as it is. The holding control amount update condition is, for example, that the actual phase has not changed over a certain time in a state where the target phase has not changed over a certain time.

  On the other hand, if it is not in the F / B mode (S100: NO), in step S103, it is determined whether or not it was in the F / B mode at the time of the previous execution of this routine, that is, the current execution of this routine ends the F / B mode. It is determined whether or not it is immediately after. If it is not immediately after the end of the F / B mode (S103: NO), the process of this routine is terminated as it is. If not (S103: YES), the process proceeds to step S104.

  When the process proceeds to step S104, it is determined in step S104 whether or not the current holding control amount value exceeds the upper limit D2 of the dead zone. If the holding control amount is equal to or less than the upper limit value D2 of the dead zone (S104: NO), the processing of this routine is terminated as it is. Otherwise, the value of the holding control amount is set to the upper limit value D2 of the dead zone in step S105. Updated. In other words, here, the holding control amount restriction process is performed so that the dead zone becomes a value on the retard side of the advance value (upper limit value D2) on the advance side.

In this embodiment, the electronic control unit 17 has a configuration corresponding to the above-described specifying unit and limiting unit.
According to the hydraulic actuator control apparatus of the present embodiment described above, the following effects can be obtained.

  (1) In the present embodiment, the electronic control unit 17 specifies the range of the dead zone of the duty command value in which the change in the phase change speed with respect to the change in the duty command value is small. Further, the electronic control unit 17 limits the holding control amount so that the value is maintained within the specified dead zone. Therefore, the value of the holding control amount is held within the dead band range of the duty command value regardless of how much the oil temperature changes. Therefore, according to the present embodiment, it is possible to suitably prevent the controllability from deteriorating at low oil temperature as a result of learning the holding control amount at high oil temperature.

  (2) In the present embodiment, the electronic control unit 17 performs the holding control amount restriction process as described above after the feedback control is completed. Therefore, under the feedback control at the time of high oil temperature, the renewal of the holding control amount is allowed and the holding control amount is limited as described above after the feedback control is finished. Therefore, according to the present embodiment, it is possible to prevent deterioration in controllability at low oil temperature as a result of learning the retention control amount at high oil temperature while ensuring retention controllability at high oil temperature. Will be able to.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, the absolute value of the phase change speed of the hydraulic actuator 1 is calculated, and the previous value is smaller than the predetermined reference value, but the duty command value when the current value is larger than the reference value. Is determined as the lower limit value D1 or the upper limit value D2 of the dead zone, thereby specifying the dead zone range of the duty command value. The method for identifying the dead zone is not limited to this, and any method can be employed. As another specific method, the minimum value of the duty command value in the range where the absolute value of the phase change speed of the hydraulic actuator 1 is equal to or less than a predetermined reference value is learned as the lower limit value D1 of the dead zone, and the duty command value in the same range There is also a method of learning the maximum value of as a dead zone upper limit value D2.

  In the above embodiment, when the target phase has not changed over a certain time and the actual phase has not changed over a certain time, the OCV duty command value at that time is stored as a holding control amount. The holding control amount is learned by updating. The learning method of the holding control amount is not limited to this, and any method can be adopted.

  In the above embodiment, the holding control amount restriction process is performed after the end of the phase feedback control. However, such a restriction process may be performed before the feedback control is started. In short, if such restriction processing is performed during the period from the end of the phase feedback control to the start of the next feedback control, the controllability at low oil temperatures can be deteriorated while maintaining the retention controllability at high oil temperatures. Can be prevented.

  In the above embodiment, the holding control amount is limited during the period when feedback control is not performed, but the controllability deteriorates at low oil temperature as a result of learning the holding control amount at high oil temperature. If this is only prevented, it can be achieved even if the holding control amount is limited during the feedback control.

  In the above embodiment, the hydraulic actuator 1 is configured to hold the phase in a state where the hydraulic pressure in the advance oil chamber 4 is higher than the hydraulic pressure in the retard oil chamber 5. In such a configuration, by limiting the holding control amount so that it becomes a value on the retard side rather than the limit value on the advance side of the dead zone, the low oil is obtained as a result of learning the holding control amount at a high oil temperature. It is possible to prevent the controllability from deteriorating when warm. On the contrary, in the state where the hydraulic pressure of the retarded oil chamber 5 is higher than the hydraulic pressure of the advanced oil chamber 4, for example, a hydraulic actuator incorporating a mechanical spring that biases the vane rotor 2 toward the advanced angle side. A hydraulic actuator configured to maintain phase can be envisaged. In the case of such a hydraulic actuator, learning of the hold control amount at high oil temperature is performed by limiting the hold control amount so that it becomes a value on the advance side rather than the limit value on the retard side of the dead zone. As a result, it is possible to prevent the controllability from deteriorating at a low oil temperature.

  In the above embodiment, the present invention is applied to a hydraulic actuator that includes two oil chambers, the advance oil chamber 4 and the retard oil chamber 5, and that makes the valve timing of the engine valve variable through supply and discharge of hydraulic oil in both oil chambers. The case of applying the control device has been described. However, the present invention is a hydraulic actuator that performs phase feedback control for converging the actual phase to the target phase and learning control for learning a control command value at which the phase change speed is “0” as a holding control amount. If so, the present invention can be similarly applied to hydraulic actuators having other uses and configurations.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic actuator, 2 ... Vane rotor, 3 ... Housing, 4 ... Advance oil chamber, 5 ... Delay oil chamber, 6 ... Oil control valve, 7 ... Sleeve, 8 ... Spool, 9 ... Solenoid, 10 ... Spring, DESCRIPTION OF SYMBOLS 11 ... Oil tank, 12 ... Hydraulic pump, 13 ... Supply oil path, 14 ... Drain oil path, 15 ... Advance angle oil path, 16 ... Delay angle oil path, 17 ... Electronic control unit (specification means, restriction means), 18 ... oil temperature sensor, 19 ... crank angle sensor, 20 ... cam angle sensor, A ... advance port, D ... drain port, R ... retard port, S ... supply port.

Claims (5)

In a control device for a hydraulic actuator that performs phase feedback control in order to converge an actual phase to a target phase, and learns a control command value at which the phase change speed is “0” as a holding control amount,
A specifying unit that specifies a range of a dead zone of the control command value in which a change in the phase change speed with respect to the change in the control command value is smaller than a predetermined value;
Limiting means for limiting the holding control amount within the specified dead zone;
A control device for a hydraulic actuator, comprising: The control device for a hydraulic actuator according to claim 1, wherein the limiting unit performs processing related to the limitation after the feedback control is completed. The control device for a hydraulic actuator according to claim 1, wherein the restriction unit performs a process related to the restriction before the feedback control is started. The hydraulic actuator includes two oil chambers, an advance oil chamber and a retard oil chamber, and the valve timing of the engine valve is variable through supply and discharge of hydraulic oil in both oil chambers. The hydraulic actuator control device according to item. The hydraulic actuator holds the phase in a state where the hydraulic pressure of the advance oil chamber is higher than the hydraulic pressure of the retard oil chamber, and the limiting means is a limit value on the advance side of the dead zone The control device for a hydraulic actuator according to claim 4, wherein the holding control amount is limited so as to be a value on the more retarded angle side.

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