Fluid pressure drive unit

Abstract

A fluid pressure drive unit is to supply a working fluid to and drive a fluid pressure actuator. The fluid pressure drive unit includes a fluid pressure pump for suctioning and discharging the working fluid, an electric motor for driving and rotating the fluid pressure pump, a power transmission mechanism for transmitting a power between a rotation shaft of the fluid pressure pump and a rotation shaft of the electric motor, and a circulation mechanism to be driven by the power transmitted by the power transmission mechanism, the circulation mechanism for guiding a lubricating fluid in the power transmission mechanism and cooling the electric motor.

The embodiments of the present invention in which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . A fluid pressure drive unit adapted to supply a working fluid to and driving a fluid pressure actuator, comprising:
 a fluid pressure pump that is configured to suction and discharge the working fluid;   an electric motor that is configured to drive and rotate the fluid pressure pump;   a power transmission mechanism that is configured to transmit a power between a rotation shaft of the fluid pressure pump and a rotation shaft of the electric motor; and   a circulation mechanism that is configured to be driven by the power transmitted by the power transmission mechanism, the circulation mechanism that is configured to guide a lubricating fluid in the power transmission mechanism and cool the electric motor.   
     
     
         2 . The fluid pressure drive unit according to  claim 1 , wherein
 the power transmission mechanism includes a first gear that is configured to rotate integrally with the rotation shaft of the fluid pressure pump, a second gear that is configured to rotate integrally with the rotation shaft of the electric motor, and an idle gear provided between the first gear and the second gear, the idle gear that is configured to transmit the power, and   the circulation mechanism has a rotation member that is configured to rotate integrally with at least any one of the first gear, the second gear, and the idle gear, the rotation member that is configured to stir up the lubricating fluid in the power transmission mechanism.   
     
     
         3 . The fluid pressure drive unit according to  claim 2 , wherein
 the circulation mechanism includes:   a supply flow passage through which the lubricating fluid stirred up by the rotation member is guided to the electric motor; and   a reflux flow passage through which the lubricating fluid guided to the electric motor is returned into the power transmission mechanism.   
     
     
         4 . The fluid pressure drive unit according to  claim 2 , wherein the rotation member is an impeller to be rotated integrally with the idle gear. 
     
     
         5 . The fluid pressure drive unit according to  claim 1 , further comprising:
 a plate having an identical surface to which the fluid pressure pump and the electric motor are attached, the plate through which the rotation shaft of the fluid pressure pump and the rotation shaft of the electric motor pass, wherein   the electric motor is arranged in parallel to the fluid pressure pump.   
     
     
         6 . The fluid pressure drive unit according to  claim 1 , further comprising:
 a fluid pressure motor that is configured to be driven and rotated with the supplied working fluid, using a rotation shaft common to the rotation shaft of the fluid pressure pump, wherein   the electric motor is capable of generating regenerative electric power by the rotation of the fluid pressure motor.   
     
     
         7 . The fluid pressure drive unit according to  claim 6 , to be applied to a hybrid construction machine in which the fluid pressure actuator is driven with a working fluid discharged from a main fluid pressure pump which is driven by a motor, wherein
 the fluid pressure motor is configured to be driven and rotated with the working fluid emitted from the fluid pressure actuator,   the electric motor that is configured to generate the regenerative electric power by the rotation of the fluid pressure motor, and is configured to drive and rotate the fluid pressure pump by using the regenerative electric power, and   the fluid pressure pump that is configured to assist drive of the fluid pressure actuator by the main fluid pressure pump with the discharged working fluid.