Self-contained energy efficient hydraulic actuator system

Abstract

The self-contained energy efficient hydraulic actuator system of the present invention includes a hydraulic cylinder, a servo motor that is configured to produce rated torque from zero RPM to maximum rated RPM with rotor speed/position feedback to a servo motor, a pump, and a solenoid valve that enables the hydraulic cylinder to maintain its position without the motor running. The system has the ability to hold a load in place without motor operation via the use of the solenoid valve, and therefore saves energy and extends the motor lifetime by minimizing the motor running time.

1 - 25 . (canceled) 
     
     
         26 . A hydraulic actuator system comprising:
 at least one piston;   at least one bi-directional hydraulic pump in fluid communication with the piston to provide hydraulic fluid to the piston and to control the position of the piston, the pump having at least one hydraulic fluid inlet and at least one hydraulic fluid outlet;   a motor operatively coupled to the pump to drive the pump;   at least one solenoid valve configured to control the hydraulic fluid between said piston and said bi-directional pump, and   a controller for controlling the solenoid valve and motor,   wherein the position of the piston can be maintained when the motor is not driving the pump and the motor can accelerate from zero to a maximum revolutions per minute (RPM) under load.   
     
     
         27 . A method for reducing the energy consumption of a hydraulic actuator system comprising a motor and at least one solenoid valve, said method comprising the steps of: receiving, at the controller, input signals corresponding to a desired operation of the functions of the system; determining by the controller an operating limit; and controlling sequentially the motor and at least one solenoid valve of the hydraulic actuator system of  claim 26 . 
     
     
         28 . A method of reducing the energy consumption of a hydraulic actuator system, said method comprising the steps of:
 i) receiving, at a controller, input signals corresponding to a desired operation of the functions of the system,   ii) determining by the controller an operating limit for the system; and   iii) controlling a motor and at least one solenoid valve sequentially at the operating limit, wherein the hydraulic actuator system comprises least one piston; at least one bi-directional hydraulic pump in fluid communication with the piston to provide hydraulic fluid to the piston and to control the position of the piston, the pump having at least one hydraulic fluid inlet and at least one hydraulic fluid outlet; the motor operatively coupled to the pump to drive the pump; the at least one solenoid valve configured to control the hydraulic fluid between said piston and said bi-directional pump, and said controller controls the at least one solenoid valve and motor, wherein the position of the piston can be maintained when the motor is not driving the pump and the motor can accelerate from zero to a maximum revolutions per minute (RPM) under load.