JP5807002B2 - Electric oil pump control device and control method thereof - Google Patents

Description

  The present invention relates to a control device for an electric oil pump that drives an electric oil pump when a power source such as an engine stops and generates a hydraulic pressure required by a transmission or the like.

  Patent Document 1 discloses an idle stop vehicle including a mechanical oil pump driven by an engine and an electric oil pump driven by electric power from a battery. During idle stop, the mechanical oil pump stops as the engine stops, so the electric oil pump is driven to supply hydraulic pressure from the electric oil pump to the transmission.

JP 2011-190900 A

  In order to continuously supply hydraulic pressure to the transmission, it is necessary to start driving the electric oil pump before the discharge pressure of the mechanical oil pump becomes zero.

  However, when the two oil pumps are driven simultaneously, the relief valve in which the discharge pressure of the electric oil pump is provided in the electric oil pump hydraulic circuit when the discharge pressure of the mechanical oil pump is higher than the discharge pressure of the electric oil pump. When the pressure is higher than the set pressure, there is a possibility that the pressure is drained as excess pressure from the relief valve. In this case, there is room for lowering the discharge pressure of the electric oil pump, that is, the power consumption and noise of the electric oil pump are reduced. There was room.

  The present invention has been made in view of such technical problems, and reduces power consumption and noise of the electric oil pump when the electric oil pump is operated before the discharge pressure of the mechanical oil pump becomes zero. For the purpose.

According to an aspect of the present invention, a mechanical oil pump driven by a power source and an electric oil pump driven by a power source are provided, and hydraulic pressure generated by the mechanical oil pump or the electric oil pump is arranged in a drive system. A control device for an electric oil pump used in a vehicle to be supplied to a hydraulic element, wherein the driving torque of the electric oil pump that obtains the hydraulic pressure required by the hydraulic element is set as a target driving torque, and the electric oil pump The actual drive torque is equal to the target drive torque, and the actual rotation speed is equal to or higher than the lower limit rotation speed that is the lower limit value of the rotation speed required to supply the hydraulic pressure required by the hydraulic element. In addition, an electric oil pump drive means for controlling the electric oil pump, a discharge pressure of the mechanical oil pump, and a discharge of the electric oil pump A hydraulic selection means for supplying to the hydraulic element by selecting one higher, the relief valve to drain the discharge pressure of the electric oil pump, the rotational speed of the electric oil pump is a lower limit rotation speed, While the discharge pressure of the mechanical oil pump is selected by the hydraulic pressure selection means and the relief valve is opened, the lower limit rotational speed of the electric oil pump is required by the hydraulic element. There is provided a control device for an electric oil pump, comprising: a rotation speed suppressing means for reducing the rotation speed to a standby rotation speed lower than a rotation speed necessary for supplying the hydraulic pressure.

According to another aspect of the present invention, a mechanical oil pump driven by a power source and an electric oil pump driven by a power source are provided, and the hydraulic pressure generated by the mechanical oil pump or the electric oil pump is arranged in a drive system. A method for controlling an electric oil pump used in a vehicle to be supplied to a hydraulic element, wherein a driving torque of the electric oil pump capable of obtaining a hydraulic pressure required by the hydraulic element is set as a target driving torque, and the electric oil pump So that the actual driving torque becomes the target driving torque, and the actual rotational speed becomes equal to or higher than the lower limit rotational speed that is the lower limit value of the rotational speed necessary to supply the hydraulic pressure required by the hydraulic element. Control the electric oil pump, and select the higher one of the discharge pressure of the mechanical oil pump and the discharge pressure of the electric oil pump. Is supplied to the serial hydraulic elements, the rotational speed of the electric oil pump is a lower limit rotation speed during the discharge pressure of the mechanical oil pump is selected, and relief to drain the discharge pressure of the electric oil pump While the valve is open, the lower limit rotational speed of the electric oil pump is lowered to a standby rotational speed that is lower than the rotational speed required to supply the hydraulic pressure required by the hydraulic element. An electric oil pump control method is provided.

  According to these aspects, when the mechanical oil pump and the electric oil pump are simultaneously driven and the discharge pressure of the mechanical oil pump is selected as the hydraulic pressure supplied to the hydraulic element, the discharge of the electric oil pump Since the pressure may be drained from a relief valve provided in the hydraulic circuit of the electric oil pump, the rotation speed of the electric oil pump is limited to the lower limit rotation speed.

  In such a situation, the lower limit rotational speed of the electric oil pump is lowered to a standby rotational speed that is lower than the rotational speed required to supply the hydraulic pressure required by the hydraulic element. The rotational speed is limited to the standby rotational speed, and the power consumption and noise of the electric oil pump can be reduced.

It is a schematic block diagram of a hybrid vehicle and its hydraulic control system. It is a schematic block diagram of the hydraulic selection circuit provided in a hydraulic control circuit. It is the flowchart which showed the control content of the electric oil pump. It is the flowchart which showed the detail of the setting process of a minimum limit rotational speed. It is the table which showed that target torque-actual torque characteristic changes by opening and closing of the EP side flapper valve. It is a table for setting a lower limit rotation speed. It is a time chart for demonstrating operation | movement of the electric oil pump at the time of a mechanical oil pump stop.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of a hybrid vehicle 10 and its hydraulic control system 20 to which an embodiment of the present invention is applied.

  The hybrid vehicle 10 includes an engine 11 and a motor generator 12 as power sources. An automatic transmission 13 is provided between these power sources and drive wheels (not shown).

  A clutch 14 is provided between the engine 11 and the motor generator 12. By changing the engagement state of the clutch 14, it is possible to switch between a hybrid travel mode using the engine 11 and the motor generator 12 as a power source and an EV travel mode using only the motor generator 12.

  The automatic transmission 13 and the clutch 14 both switch the power transmission state by the hydraulic pressure supplied from the hydraulic control circuit 23 described later. In the following description, the automatic transmission 13 and the clutch 14 are collectively referred to. Expressed as a hydraulic element.

  The hydraulic control system 20 will be described. The hydraulic control system 20 includes a mechanical oil pump 21, an electric oil pump 22, a hydraulic control circuit 23, and a controller 24.

  The mechanical oil pump 21 is provided on the input shaft of the automatic transmission 13 and is driven by the engine 11 or the motor generator 12 to generate hydraulic pressure corresponding to the rotational speed. The hydraulic pressure generated by the mechanical oil pump 21 is sent to the hydraulic control circuit 23.

  The electric oil pump 22 is driven by power supply from a battery (not shown). The electric oil pump 22 is driven when the input rotation decreases and the discharge pressure of the mechanical oil pump 21 decreases, and the hydraulic pressure generated by the electric oil pump 22 is sent to the hydraulic control circuit 23.

  The hydraulic control circuit 23 is a hydraulic circuit composed of a plurality of hydraulic control valves. Based on the hydraulic control signal from the controller 24, the hydraulic control circuit 23 adjusts the hydraulic pressure required by the hydraulic element using the hydraulic pressure sent from the mechanical oil pump 21 or the electric oil pump 22 as a base pressure, and supplies the hydraulic pressure to the hydraulic element. .

  The hydraulic pressure control circuit 23 includes a hydraulic pressure selection circuit 30 for automatically selecting the higher hydraulic pressure as a source pressure in a situation where both the mechanical oil pump 21 and the electric oil pump 22 generate hydraulic pressure. I have.

  FIG. 2 is a schematic configuration diagram of a hydraulic pressure selection circuit 30 provided in the hydraulic pressure control circuit 23.

  The hydraulic pressure selection circuit 30 is a circuit with two inputs and one output. On the input side, a mechanical oil pump 21 and an electric oil pump 22 are respectively provided with an MP hydraulic pressure supply path 31 and an MP side flapper valve 32, an EP hydraulic pressure supply path 33 and an EP side flapper valve. 34 is connected. The output side is connected to a hydraulic control valve (not shown).

  The MP side flapper valve 32 includes a valve body 321 and a spring 322 that biases the valve body 321 in the valve closing direction. When the mechanical oil pump 21 generates hydraulic pressure, the valve element 321 is pushed into the hydraulic pressure selection circuit 30 against the spring 322, and the MP side flapper valve 32 is opened. Similarly, the EP-side flapper valve 34 includes a valve body 341 and a spring 342, and opens when the electric oil pump 22 generates hydraulic pressure.

  A relief valve 35 is provided in the EP hydraulic pressure supply path 33. The relief pressure, which is the pressure at which the relief valve 35 opens, is higher than the hydraulic pressure that needs to be generated by the electric oil pump 22 when the discharge pressure of the mechanical oil pump 21 decreases (when the vehicle stops), and the electric oil pump 22 Is set lower than the hydraulic pressure generated by the electric oil pump 22 when driven at the maximum torque.

  The relief valve 35 is provided so that the electric oil pump 22 can be driven even when the mechanical oil pump 21 generates hydraulic pressure. In other words, without the relief valve 35, the EP side flapper valve 34 is closed in a situation where the mechanical oil pump 21 is generating hydraulic pressure, and the hydraulic pressure of the EP hydraulic pressure supply passage 33 increases even if the electric oil pump 22 is driven. As a result, the electric oil pump 22 cannot be driven. In the present embodiment, a relief valve 35 is provided, and when the EP side flapper valve 34 is closed and the hydraulic pressure of the EP hydraulic pressure supply passage 33 is increased, the relief valve 35 is opened and the hydraulic pressure of the EP hydraulic pressure supply passage 33 is indicated by an arrow in the figure. By draining as shown, the electric oil pump 22 can be driven.

  Note that the relief pressure of the relief valve 35 is set higher than the hydraulic pressure that needs to be generated by the electric oil pump 22 when the discharge pressure of the mechanical oil pump 21 is reduced (when the vehicle stops). This is because even when the EP side flapper valve 34 is opened and the hydraulic pressure of the electric oil pump 22 is supplied, the relief valve 35 is opened and the required hydraulic pressure cannot be supplied.

  FIG. 3 shows the control content of the electric oil pump 22. The control content of the electric oil pump 22 performed by the controller 24 will be described with reference to this.

  First, in S11, the controller 24 determines whether the actual rotational speed of the mechanical oil pump 21 is lower than the EP operation threshold value. The EP operation threshold value is a threshold value for starting driving of the electric oil pump 22 when the vehicle shifts from the running state to the stopped state, and the electric oil pump when the vehicle shifts from the stopped state to the running state. This is also a threshold value for stopping the driving of 22. If the actual rotational speed of the mechanical oil pump 21 is lower than the EP operation threshold value, the process proceeds to S12.

  In S <b> 12, the controller 24 sets a target drive torque for the electric oil pump 22. The target drive torque is obtained based on the input torque from the engine 11 and the motor generator 12 to the hydraulic element, the temperature of the oil supplied to the hydraulic element, etc., and the hydraulic pressure required by the hydraulic element is obtained. Is set to the drive torque required to be supplied from the vehicle.

  In S <b> 13, the controller 24 sets the lower limit rotational speed of the electric oil pump 22. The lower limit rotational speed is a lower limit value of the rotational speed of the electric oil pump 22 that can reliably supply the hydraulic pressure required by the hydraulic element even if there are manufacturing variations of the pump and fluctuations in the oil temperature. The lower limit rotational speed is set by a subroutine shown in FIG. 4, which will be described later.

  In S14, the controller 24 estimates the actual rotational speed and the actual drive torque of the electric oil pump 22. The actual rotation speed can be obtained from a change in the current value of the electric oil pump 22, and the actual drive torque can be obtained based on the drive torque-rotation speed characteristics of the motor of the electric oil pump 22.

  In S15, when the actual rotation speed of the electric oil pump 22 is higher than the lower limit rotation speed, the controller 24 sets the drive current of the electric oil pump 22 so that the actual drive torque of the electric oil pump 22 becomes the target drive torque. Control (torque control). On the other hand, when the actual rotational speed of the electric oil pump 22 is lower than the lower limit rotational speed, the drive current of the electric oil pump 22 is controlled (rotational speed control) so that the actual rotational speed becomes the lower limit rotational speed. .

  Even if the drive torque of the electric oil pump 22 is controlled to the target drive torque, there is a possibility that the discharge pressure of the electric oil pump 22 decreases due to pump manufacturing variations and oil temperature fluctuations, and the required hydraulic pressure cannot be supplied. The hydraulic pressure required by the hydraulic element can be reliably supplied by performing the rotational speed control in addition to the torque control so that the rotational speed of the electric oil pump 22 does not fall below the lower limit rotational speed. .

  According to the above control, the electric oil pump 22 is driven in a situation where the rotational speed of the mechanical oil pump 21 is lower than the EP operation threshold value, and the hydraulic pressure required by the hydraulic element can be secured. The torque and the rotational speed are controlled.

  By the way, even if the rotational speed of the mechanical oil pump 21 is lower than the EP operation threshold value, the hydraulic pressure generated by the mechanical oil pump 21 is electric when the rotational speed of the mechanical oil pump 21 is not sufficiently lowered. Since the hydraulic pressure generated by the oil pump 22 is higher and the EP-side flapper valve 34 is closed, the load on the electric oil pump 22 is high even when the electric oil pump 22 is started, and the actual rotational speed of the electric oil pump 22 is increased. It may be difficult to increase to the lower limit of the rotational speed limit.

  For this reason, in such a situation, the rotational speed control based on the lower limit rotational speed is performed, the drive current of the electric oil pump 22 is increased, and the rotational speed of the electric oil pump 22 is increased to the lower limit rotational speed. Further, in response to the increase in the drive current, the actual drive torque of the electric oil pump 22 is increased to the maximum drive torque.

  Since the relief pressure of the relief valve 35 is set lower than the hydraulic pressure when the electric oil pump 22 is driven with the maximum driving torque, the relief is achieved when the actual driving torque of the electric oil pump 22 is increased to the maximum driving torque. The valve 35 is opened, and the discharge pressure of the electric oil pump 22 is drained from the relief valve 35.

  When the rotation speed of the mechanical oil pump 21 is sufficiently lowered and the hydraulic pressure generated by the mechanical oil pump 21 is lower than the hydraulic pressure generated by the electric oil pump 22, the EP side flapper valve 34 is opened and the relief valve 35 is closed. Then, the hydraulic pressure generated by the electric oil pump 22 is supplied to the hydraulic control circuit 23.

  Here, the hydraulic pressure generated by the electric oil pump 22 while the EP side flapper valve 34 is closed is only drained from the relief valve 35 while the relief valve 35 is open, It can be said that the electric oil pump 22 is driven wastefully.

  Therefore, in this embodiment, the lower limit rotational speed of the electric oil pump 22 while the EP side flapper valve 34 is closed is lowered to a lower standby rotational speed (for example, 500 rpm), and the rotational speed of the electric oil pump 22 is reduced. By suppressing, the power consumption and noise of the electric oil pump 22 are reduced.

  FIG. 4 shows details of the lower limit rotation speed setting process in S13 of FIG.

  First, in S21, the controller 24 determines whether or not the EP side flapper valve 34 is closed. In the situation where the EP-side flapper valve 34 is closed, as described above, the load on the electric oil pump 22 becomes high. Therefore, the rotation speed of the electric oil pump 22 is limited to the lower limit by the torque control and the rotation speed control of the electric oil pump. As the rotational speed is reached, the actual driving torque of the electric oil pump 22 is increased to the maximum driving torque, and the actual driving torque of the electric oil pump 22 is larger than the target driving torque as shown in FIG. It can be determined that the flapper valve 34 is closed. If the EP side flapper valve 34 is open, the process proceeds to S22, and if it is closed, the process proceeds to S24.

  In S22, the controller 24 resets the counter. This counter is for measuring the time during which the actual rotational speed of the electric oil pump 22 is limited to the lower limit rotational speed, as will be described later.

  In S23, the controller 24 sets the lower limit rotational speed to a map value obtained by referring to a table that defines the relationship between the hydraulic pressure and oil temperature required for the hydraulic element shown in FIG. 6 and the lower limit rotational speed. .

  In S24, the controller 24 determines whether the actual rotational speed of the electric oil pump 22 is the lower limit rotational speed. If it is not the lower limit rotational speed, the process proceeds to S22, and if it is, the process proceeds to S25.

  In S25, the controller 24 increments the counter and measures an elapsed time after the actual rotational speed of the electric oil pump 22 is limited to the lower limit rotational speed.

  In S26, the controller 24 determines whether a predetermined time has elapsed since the actual rotational speed of the electric oil pump 22 was limited to the lower limit rotational speed. If it is determined that the predetermined time has elapsed, the process proceeds to S27. The predetermined time is sufficient to determine that the actual rotational speed of the electric oil pump 22 is limited to the lower limit rotational speed.

  In S27, the controller 24 sets the lower limit rotational speed of the electric oil pump 22 to a standby rotational speed (for example, 500 rpm) lower than the map value obtained by referring to S23.

  According to the above process, when the state that the EP side flapper valve 34 is closed and the actual rotational speed of the electric oil pump 22 is the lower limit rotational speed, the process proceeds from S26 to S27, The lower limit rotational speed is lowered to the standby rotational speed, and the actual rotational speed of the electric oil pump 22 is limited to the standby rotational speed.

  If the EP-side flapper valve 34 is opened while the actual rotational speed of the electric oil pump 22 is limited to the standby rotational speed, the load on the electric oil pump 22 is reduced and the actual rotational speed of the electric oil pump 22 is set to the standby rotational speed. Since the speed is higher than the speed, the process proceeds from S24 to S22 and S23, and the lower limit rotational speed is returned to the map value.

  Then, the effect of the said embodiment is demonstrated.

  FIG. 7 shows a state in which the electric oil pump 22 operates when the vehicle speed is gradually decreased, the vehicle is stopped and the engine is stopped, the mechanical oil pump 21 is stopped, and then the vehicle is started again.

  When the vehicle speed gradually decreases, the actual rotational speed of the mechanical oil pump 21 becomes lower than the EP operation threshold value, so that the driving of the electric oil pump 22 is started (time t1).

  In this state, since the EP-side flapper valve 34 is closed and the load on the electric oil pump 22 is large, the actual rotation speed of the electric oil pump 22 is limited to the lower limit rotation speed. Further, the actual drive torque of the electric oil pump 22 becomes the maximum drive torque so as to maintain the actual rotation speed at the lower limit rotation speed, and thereby the relief valve 35 is opened.

  When this state continues for a predetermined time, it is determined that the actual rotational speed of the electric oil pump 22 is limited to the lower limit rotational speed, and the lower limit rotational speed is lowered to the standby rotational speed (time t2). Thereby, the power consumption and noise of the electric oil pump 22 corresponding to the shaded area A in the figure are reduced.

  When the actual rotational speed of the mechanical oil pump 21 further decreases and the hydraulic pressure generated by the mechanical oil pump 21 becomes lower than the hydraulic pressure generated by the electric oil pump 22, the EP side flapper valve 34 is opened and is required by the hydraulic element. Hydraulic pressure is supplied from the electric oil pump 22 (time t3). At this time, the lower limit rotational speed is returned to the map value that can supply the hydraulic pressure required by the hydraulic element, and the rotational speed of the electric oil pump 22 rises to the map value. Even if there is a fluctuation, it is possible to reliably supply the hydraulic pressure required by the hydraulic element.

  While the vehicle is stopped, the hydraulic pressure required by the hydraulic element is supplied exclusively by the electric oil pump 22 (time t4 to t5).

  Thereafter, when the vehicle starts, the actual rotational speed of the mechanical oil pump 21 increases, and the hydraulic pressure generated by the mechanical oil pump 21 becomes higher than the hydraulic pressure generated by the electric oil pump 22, the MP side flapper valve 32 is opened, The EP side flapper valve 34 is closed. As a result, hydraulic pressure is supplied from the mechanical oil pump 21 to the hydraulic element. Further, the actual rotational speed of the electric oil pump 22 is again limited to the lower limit rotational speed, the actual driving torque of the electric oil pump 22 becomes the maximum driving torque, and the relief valve 35 is opened (time t6).

  When this state continues for a predetermined time, the lower limit rotational speed is again lowered to the standby rotational speed (time t7). Thereby, the power consumption / noise of the electric oil pump 22 corresponding to the shaded portion B in the figure is reduced.

  Then, the actual rotational speed of the mechanical oil pump 21 is further increased, the EP-side flapper valve 34 is closed, and the discharge pressure from the mechanical oil pump 21 is determined to sufficiently secure the hydraulic pressure necessary for torque transmission. When the EP operation threshold value is exceeded, the electric oil pump 22 is stopped (time t8).

  As described above, in the present embodiment, when the mechanical oil pump 21 and the electric oil pump 22 are simultaneously driven and the mechanical oil pump 21 is selected by the hydraulic pressure selection circuit 30, the rotational speed control of the electric oil pump 22 is performed. Therefore, the electric oil pump 22 is operated with the maximum driving torque, so that the load of the electric oil pump 22 is high, and the rotation speed of the electric oil pump 22 is limited to the lower limit rotation speed.

  At this time, the lower limit rotational speed is lowered to a standby rotational speed lower than the rotational speed necessary for supplying the hydraulic pressure required by the hydraulic element, so that the rotational speed of the electric oil pump 22 is changed to the standby rotational speed. The power consumption and noise of the electric oil pump 22 can be reduced (effect corresponding to claims 1 and 5).

  Further, when the discharge pressure selected by the hydraulic pressure selection circuit 30 is switched from the discharge pressure of the mechanical oil pump 21 to the discharge pressure of the electric oil pump 22, the lower limit rotational speed supplies the hydraulic pressure required by the hydraulic element. Therefore, the hydraulic pressure required by the hydraulic element can be reliably supplied (effect corresponding to claim 2).

  Further, which pump discharge pressure is selected by the hydraulic pressure selection circuit 30 can be determined based on the magnitude relationship between the actual drive torque of the electric oil pump 22 and the target drive torque. Alternatively, when the discharge pressure of the selected pump is changed, the load of the electric oil pump 22 changes and the actual rotational speed changes. Therefore, the actual rotational speed of the electric oil pump 22 may be determined. Any of the methods has an effect that a sensor for detecting the state of the hydraulic pressure selection circuit 30 is not required (effect corresponding to claims 3 and 4).

  The embodiment of the present invention has been described above, but the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

13 Automatic transmission (hydraulic element)
14 Clutch (hydraulic element)
21 mechanical oil pump 22 electric oil pump 24 controller (control device, electric oil pump drive means, rotational speed suppression means)
30 Hydraulic selection circuit (hydraulic selection means)

Claims (5)

A mechanical oil pump driven by a power source and an electric oil pump driven by a power source, and used in a vehicle that supplies hydraulic pressure generated by the mechanical oil pump or the electric oil pump to a hydraulic element arranged in a drive system A control device for an electric oil pump,
The drive torque of the electric oil pump that can obtain the oil pressure required by the hydraulic element is set as the target drive torque, the actual drive torque becomes the target drive torque, and the actual rotational speed is required by the hydraulic element. Electric oil pump drive means for controlling the electric oil pump so as to be equal to or higher than a lower limit rotation speed that is a lower limit value of the rotation speed required to supply the hydraulic pressure,
A hydraulic pressure selection means for selecting the higher one of the discharge pressure of the mechanical oil pump and the discharge pressure of the electric oil pump to supply to the hydraulic element;
A relief valve for draining the discharge pressure of the electric oil pump;
While the rotational speed of the electric oil pump is a lower limit rotational speed, the electric oil pump is operated while the discharge pressure of the electric oil pump is not selected by the hydraulic pressure selection means and while the relief valve is opened. A rotational speed suppression means for lowering the lower limit rotational speed of the oil pump to a standby rotational speed lower than the rotational speed necessary for supplying the hydraulic pressure required by the hydraulic element;
An electric oil pump control apparatus comprising: It is a control apparatus of the electric oil pump of Claim 1, Comprising:
When the discharge pressure selected by the hydraulic pressure selection unit is changed from the discharge pressure of the mechanical oil pump to the discharge pressure of the electric oil pump, the rotation speed suppression unit sets the lower limit rotation speed by the hydraulic element. Return to the rotational speed necessary to supply the required hydraulic pressure,
A control device for an electric oil pump. The control device for an electric oil pump according to claim 1 or 2,
The rotational speed suppression means determines which of the discharge pressure of the mechanical oil pump and the discharge pressure of the electric oil pump is selected by the hydraulic pressure selection means, the actual drive torque of the electric oil pump and the target drive torque. Judgment based on the magnitude relationship of
A control device for an electric oil pump. The control device for an electric oil pump according to claim 1 or 2,
The rotational speed suppression means determines whether the discharge pressure of the mechanical oil pump or the discharge pressure of the electric oil pump is selected by the hydraulic pressure selection means based on a change in the actual rotational speed of the electric oil pump. ,
A control device for an electric oil pump. A mechanical oil pump driven by a power source and an electric oil pump driven by a power source, and used in a vehicle that supplies hydraulic pressure generated by the mechanical oil pump or the electric oil pump to a hydraulic element arranged in a drive system An electric oil pump control method,
The drive torque of the electric oil pump that can obtain the oil pressure required by the hydraulic element is set as the target drive torque, the actual drive torque becomes the target drive torque, and the actual rotational speed is required by the hydraulic element. The electric oil pump is controlled so as to be equal to or higher than a lower limit rotation speed that is a lower limit value of the rotation speed required to supply the hydraulic pressure,
Select the higher one of the discharge pressure of the mechanical oil pump and the discharge pressure of the electric oil pump to supply to the hydraulic element,
The rotational speed of the electric oil pump is the lower limit rotational speed, and the relief valve that drains the discharge pressure of the electric oil pump is opened while the discharge pressure of the mechanical oil pump is selected . during lowers said lower limit revolution speed of the electric oil pump, to a lower standby rotational speed than the rotational speed needed to supply the hydraulic pressure required in the hydraulic element,
A control method for an electric oil pump.

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