Hydraulic hybrid power system

A hydraulic hybrid vehicle including a heat engine, two or more wheels, a working fluid and a compressor for pressurizing said working fluid, said compressor being rotatably coupled to said one or more wheels for converting vehicle inertia into an increase in pressure of the working fluid during braking of said vehicle,

• said compressor having a compressor outlet for releasing the compressed working fluid, said working fluid having a first specific volume, said first specific volume being measured at said compressor outlet, said working fluid having a first high pressure state, said first high pressure state being measured at said compressor outlet,
• and a motor for generating shaft power from said working fluid, said motor having a motor outlet for releasing said working fluid, said working fluid having a first low pressure state, said first low pressure state being measured at said motor outlet, wherein said motor includes means for converting the reduction in pressure of said working fluid from said first high pressure state to said first low pressure state into said shaft power,
• said heat engine further having waste heat,
• wherein, said hydraulic hybrid vehicle further includes a heat exchanger for transferring said waste heat from said heat engine to said working fluid down stream of said compressor, thereby increasing the specific volume of said working fluid, said heat exchanger being located downstream of said compressor and upstream of said motor,
• said heat exchanger having a heat exchanger outlet for releasing the heated working fluid, and said working fluid having a second specific volume, said second specific volume being measured at said heat exchanger outlet, said second specific volume generally being larger than said first specific volume due to said heat exchanger, thereby providing an increase in the volumetric flow rate entering the motor thereby providing an increase in shaft power generated by said motor,
• wherein inertial braking energy of said vehicle is employed to compress said working fluid, and said heat exchanger is employed to transfer waste heat from said heat engine to said working fluid for increasing the specific volume of said working fluid, thereby providing an increase in shaft power produced by said motor, and thereby providing the combined vehicle fuel economy benefits of hydraulic regenerative braking and waste heat recovery.