Patent ID: 8639422

Claim:
A cooling system to be mounted on a hybrid working machine, the working machine comprising: an engine ( 11 ); a hydraulic pump ( 12 ) driven by the engine; hydraulic actuators ( 14 ) driven by a hydraulic fluid discharged from the hydraulic pump; a first electric motor ( 22 ) driven by the engine; an electrical storage device ( 23 ) for storing the electric power generated by the first electric motor and a second electric motor ( 24 ); the second electric motor driven by the electric power generated by the first electric motor and by the electric power stored on the electrical storage device; and a power control unit (PCU) ( 25 ) for controlling the operation of the first electric motor and the second electric motor as well as controlling the charging and discharging of the electrical storage device, the cooling system comprising: a radiator ( 31 ) for cooling a coolant; and a pump ( 32 ) for circulating the coolant, the cooling system being designed to cool each of electric components including the electrical storage device, the PCU, and the second electric motor by causing the pump to circulate the coolant cooled by the radiator, wherein the cooling system further comprises a liquid temperature detection sensor ( 51 to 54 ) for detecting the liquid temperature of the coolant, and the PCU has a heating mode functionality ( 25 a , 25 b , 25 c ) that helps any of the electric components to generate heat when the PCU is in a low-temperature mode in which the detected liquid temperature is less than a first threshold.