Electric pump device

Abstract

There is provided an electric pump device that can suppress the generation of vibration or noise. When reducing hydraulic pressure supplied from an oil pump with the increase of hydraulic pressure supplied from a main pump driven by an engine, an electric oil pump ECU performs a pressure reducing control gradually reducing the hydraulic pressure.

1 . An electric pump device that includes an oil pump generating hydraulic pressure, a motor driving the oil pump, and a controller controlling an operation of the oil pump through a supply of drive power to the motor, and is provided in a hydraulic circuit supplying operating oil to a hydraulic operating device together with another oil pump,
 wherein the controller operates the oil pump to complement a supply of hydraulic pressure to the hydraulic operating device when the supply of hydraulic pressure to the hydraulic operating device performed by the another oil pump is stopped, and   the controller performs a pressure reducing control gradually reducing hydraulic pressure supplied from the oil pump when the supply of hydraulic pressure to the hydraulic operating device is switched to the another oil pump from the oil pump.   
     
     
         2 . The electric pump device according to  claim 1 ,
 wherein the motor is formed of a sensorless type brushless motor,   the controller estimates a rotational position of a rotor based on induced voltages generated at motor coils, and   the controller maintains a motor angular velocity at which the rotational position can be detected based on the induced voltages, in a state where hydraulic pressure is supplied to the hydraulic operating device by the another oil pump.   
     
     
         3 . The electric pump device according to  claim 2 , wherein
 the controller changes a reduction rate of hydraulic pressure supplied from the oil pump in the pressure reducing control.   
     
     
         4 . The electric pump device according to  claim 2 , wherein
 the controller reduces the hydraulic pressure stepwise while temporarily maintaining the hydraulic pressure supplied from the oil pump in the pressure reducing control.   
     
     
         5 . The electric pump device according to  claim 2 , wherein
 the controller increases the hydraulic pressure once before reducing the hydraulic pressure supplied from the oil pump in the pressure reducing control.