Importance

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Abstract

The hydraulic regenerative drive system for a vehicle includes an electronic controller, a hydraulic control circuit that receives control signals from the electronic controller, a reservoir in fluid communication with the hydraulic control circuit, a pump/motor unit having a controlled-angle swash plate element providing variable displacement, an accumulator in fluid communication with the hydraulic control circuit and a pump/motor unit speed sensor and pump/motor unit pressure sensor providing measured speed and measured pressure signals to the electronic controller. The electronic controller generates a torque signal and a modified engine throttle signal on the basis of a mathematical model, converts the torque signal to a swash plate angle, and controls a controlled-torque retard mode of operation and a controlled torque propulsion mode of operation. The electronic controller also performs a conversion between the torque signal and swash plate angle on the basis of searching predetermined characteristics of torque versus pressure versus speed.

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First Claim