Energy storage and reutilization for a single-rod electro-hydrostatic actuator

An electro-hydrostatic actuator system comprising:

• an electro-hydrostatic actuator (EHA) comprising:
• a first bidirectional fixed displacement pump-motor rotationally coupled to an electric motor that is operable to drive a pumping operation of said first bidirectional pump-motor;
• a hydraulic cylinder;
• and
• in an EHA circuit in which the first bidirectional pump-motor and the hydraulic cylinder are both installed, EHA valving and connections between the first bidirectional pump-motor and the hydraulic cylinder by which the EHA is operable in four distinct operating quadrants, including a first actuator-extending pumping quadrant, a second actuator-extending motoring quadrant, a third actuator-retracting pumping quadrant and a fourth actuator-retraction motoring quadrant;
• and
• an energy storing and reutilizing (ESR) system comprising:
• a second fixed displacement pump-motor rotationally linked to the first bidirectional pump-motor via a rotational interconnection that is continuously maintained therebetween throughout all operational modes of the ESR system;
• a hydraulic accumulator;
• and
• in a fluidically separate ESR circuit of fluidically isolated relationship to the EHA circuit, and in which the second pump-motor and the hydraulic accumulator are installed, ESR valving and connections between said second pump-motor and said hydraulic accumulator that, collectively, are configured to (a) during at least one of the motoring quadrants, operate the ESR system in an energy storage mode charging the hydraulic accumulator using driven rotation of the second pump-motor, via the rotational interconnection, from load-driven motoring of the first bidirectional pump-motor;
• (b) during at least one of the pumping quadrants, operate the ESR system in an energy reutilizing mode driving the second pump-motor from stored energy in the accumulator, and thereby, via said rotational interconnection, supplementing driven rotation of the first bidirectional pump-motor in assistive relation to the electric motor, and (c) switch the ESR system into an idle flow-circulation mode, in which the accumulator is hydraulically decoupled from the second bidirectional fixed displacement pump-motor, based on sensor-detection of accumulator pressure conditions denoting an unsustainability of the energy reutilizing mode.