Power system and method of controlling power system

Abstract

A power system including: a power unit, a supply pump for feeding liquid oil for lubricating the power unit; a supply flow path for guiding, to the power unit, the oil fed from the supply pump; a return pump for returning the oil having flowed through the power unit; a return flow path for guiding, to the return pump, the oil having flowed through the power unit; a circulation flow path for guiding, to the supply pump, the oil returned by the return pump; a bypass flow path connecting the supply flow path and the return flow path; and an on-off valve for opening and closing the bypass flow path.

1 . A power system comprising:
 a power unit;   a supply pump configured to feed oil in a liquid form for lubricating the power unit;   a supply flow path configured to guide, to the power unit, the oil fed from the supply pump;   a return pump configured to return the oil having flowed through the power unit;   a return flow path configured to guide, to the return pump, the oil having flowed through the power unit;   a circulation flow path configured to guide, to the supply pump, the oil returned by the return pump;   a bypass flow path connecting the supply flow path and the return flow path; and   an on-off valve configured to open and close the bypass flow path.   
     
     
         2 . The power system according to  claim 1 , wherein
 a capacity of the return pump is larger than a capacity of the supply pump.   
     
     
         3 . The power system according to  claim 2 , wherein
 the oil led out from the power unit is mixed with gas, and   the circulation flow path is provided with a gas-liquid separator configured to separate the gas from the oil.   
     
     
         4 . The power system according to  claim 1 , wherein
 the on-off valve comprises a relief valve that is pushed by the oil to open when a pressure of the oil supplied from the supply pump reaches a predetermined pressure upper limit value.   
     
     
         5 . The power system according to  claim 1 , further comprising:
 a motor configured to drive the supply pump and the return pump.   
     
     
         6 . The power system according to  claim 5 , wherein
 the motor is a sole motor, and   the power system further comprises a power transmission mechanism configured to transmit a rotational driving force of the motor to the supply pump and the return pump.   
     
     
         7 . The power system according to  claim 5 , further comprising:
 a controller comprising one or more processors that execute computer-executable instructions stored in a memory,   wherein the one or more processors execute the computer-executable instructions to cause the controller to control the motor to set torque of the motor to predetermined target torque in a state where the on-off valve is opened.   
     
     
         8 . The power system according to  claim 7 , wherein
 the one or more processors cause the controller to control the motor to set a rotational speed of the supply pump to a target rotational speed in a state where the on-off valve is closed.   
     
     
         9 . The power system according to  claim 1 , wherein
 the power unit comprises:   a bearing that rotatably supports a rotor; and   a lubrication flow path configured to allow the oil to flow through the bearing.   
     
     
         10 . A method of controlling a power system, wherein the power system comprises:
 a power unit;   a supply pump configured to feed oil in a liquid form, for lubricating the power unit;   a supply flow path configured to guide, to the power unit, the oil fed from the supply pump;   a return pump configured to return the oil having flowed through the power unit;   a return flow path configured to guide, to the return pump, the oil having flowed through the power unit;   a circulation flow path configured to guide, to the supply pump, the oil returned by the return pump;   a bypass flow path connecting the supply flow path and the circulation flow path;   an on-off valve configured to open and close the bypass flow path;   a motor configured to drive the supply pump and the return pump; and   a controller comprising one or more processors that execute computer-executable instructions stored in a memory,   the method comprising:   causing, by the one or more processors executing computer-executable instructions, the controller to control the motor to set torque of the motor to predetermined target torque in a state where the on-off valve is opened.   
     
     
         11 . The method of controlling the power system according to  claim 10 , wherein
 the one or more processors cause the controller to control the motor to set a rotational speed of the supply pump to a target rotational speed in a state where the on-off valve is closed.