Patent ID: 8302720

Claim:
An energy storage system for a hybrid vehicle including an internal combustion engine having an output shaft and a transmission operably coupled to the output shaft, the energy storage system comprising: a reservoir containing working fluid; a first reversible pump/motor in fluid communication with the reservoir and selectively drivably coupled to the output shaft of the engine; a second reversible pump/motor in fluid communication with the reservoir and selectively drivably coupled to an output shaft of the transmission for torque transfer between the second reversible pump/motor and the transmission output shaft; and an accumulator containing working fluid and gas, the accumulator in selective fluid communication with at least one of the first and second reversible pump/motors to deliver pressurized working fluid to the one of the first and second reversible pump/motors when operating as a motor for transferring torque to the corresponding one of the engine output shaft and the transmission output shaft, and to receive pressurized working fluid discharged by the one of the first and second reversible pump/motors when operating as a pump.