Hydraulic energy storage multi-speed transmission

Claim 1

In a wheeled vehicle, a hydraulic multi-speed, multi-torque transmission system for selectively storing energy normally lost in braking the vehicle and releasing the stored energy to aid in accelerating the vehicle, said system comprising: (a) an accumulator for hydraulically pressurizing a compressible gas and storing hydraulic fluid under the pressure of said gas; (b) hydraulic pump means mechanically coupled to the wheels of said vehicle for being driven by said wheels, said pump means having an inlet and an outlet, the outlet of said pump means being selectively hydraulically connected to said accumulator for pumping hydraulic fluid into said accumulator to pressurize said gas in response to the driving of said pump means by said wheels to brake said vehicle; (c) hydraulic motor means mechanically coupled to the wheels of said vehicle for driving said wheels, said motor means having an inlet and an outlet, the inlet of said motor means being selectively hydraulically connected to said accumulator for receiving hydraulic fluid under pressure therefrom, said motor means comprising a plurality of fixed displacement hydraulic motors mechanically coupled to said vehicle wheels; (d) an engine mounted on said vehicle; (e) fixed displacement hydraulic pump means driven by said engine, said fixed displacement pump means having an inlet and an outlet, said outlet being connected to the inlet of said hydraulic motor means for supplying hydraulic fluid under pressure to said motor means; and (f) selectively operable valve means interposed between the inlet of said motor means and the outlet of said engine-driven fixed displacement pump means for selectively directing the flow of hydraulic fluid under pressure from said fixed displacement pump means alternatively to any one or more of said plurality of fixed displacement hydraulic motors.