Regenerative hydraulic systems and methods of use

A hydraulic system comprising:

• at least first and second hydraulic actuators, each of the first and second hydraulic actuators having first and second chambers fluidically connected to first and second ports, respectively;
• at least first, second, third and fourth sets of hydraulic valves fluidically connected to the first and second hydraulic actuators with a first conduit system that fluidically connects the first set of hydraulic valves to the first port of the first hydraulic actuator, the second set of hydraulic valves to the second port of the first hydraulic actuator, the third set of hydraulic valves to the first port of the second hydraulic actuator, the fourth set of hydraulic valves to the second port of the second hydraulic actuator;
• a plurality of positive displacement units having pumping and motoring modes, the positive displacement units being fluidically connected to the first and second hydraulic actuators through the first, second, third and fourth sets of hydraulic valves so that a fluid flows from the positive displacement units and through at least some of the first, second, third and fourth sets of hydraulic valves to at least one of the first and second hydraulic actuators when the positive displacement units are in the pumping mode thereof, and the fluid flows from at least one of the first and second hydraulic actuators and through at least some of the first, second, third and fourth sets of hydraulic valves to the positive displacement units when the positive displacement units are in the motoring mode thereof;
• drive shafts associated with the first and second positive displacement units and interconnected with each other such that the drive shafts are rotatably coupled and cause the first and second positive displacement units to operate in unison;
• at least one motor connected to the drive shafts of the positive displacement units for rotating the drive shafts;
• at least one reservoir from which the fluid can be drawn by the positive displacement units when operating in their pumping modes and to which the fluid can be returned by the positive displacement units when operating in their motoring modes;
• a first conduit system containing at least a first hydraulic valve of each of the first, second, third and fourth sets of hydraulic valves for selectively fluidically connecting a first of the positive displacement units to either or both of the first and second hydraulic actuators, the first conduit system continuously fluidically connecting the first hydraulic valves;
• a second conduit system containing at least a second hydraulic valve of each of the sets of hydraulic valves for selectively fluidically connecting the first and second hydraulic actuators to the reservoir, the second conduit system continuously fluidically connecting the second hydraulic valves;
• a third conduit system containing at least a third hydraulic valve of each of the sets of hydraulic valves for selectively fluidically connecting a second of the positive displacement unit to either or both of the first and second hydraulic actuators, the third conduit system continuously fluidically connecting the third hydraulic valves and being adapted to transfer the fluid between the first and second hydraulic actuators;
• first valve means for selectively fluidically isolating the first conduit system from the third conduit system and selectively fluidically connecting the first conduit system to the third conduit system;
• and
• second valve means for selectively fluidically isolating the second conduit system from the third conduit system and selectively fluidically connecting the second conduit system to the third conduit system;
• wherein the hydraulic system is operable to:
• supplement a resistive load generated by the fluid within one of the first and second hydraulic actuators with an assistive load generated by the fluid in the other of the first and second hydraulic actuators by transferring the fluid within the other of the first and second hydraulic actuators to the one of the first and second hydraulic actuators through the third conduit system;
• supplement the resistive load generated by the fluid within the one of the first and second hydraulic actuators by transferring the fluid from the reservoir to the one of the first and second hydraulic actuators through the third conduit system while operating the second positive displacement unit in the pumping mode thereof;
• and
• recover energy by transferring the fluid within the other of the first and second hydraulic actuators to the reservoir through the third conduit system while operating the second positive displacement unit in the motoring mode thereof.

A hydraulic system comprising:

• at least first and second hydraulic actuators;
• multiple sets of hydraulic valves fluidically connected to the first and second hydraulic actuators;
• at least a first positive displacement unit having pumping and motoring modes, the first positive displacement unit being selectively fluidically connectable to the first and second hydraulic actuators through the sets of hydraulic valves;
• at least one motor connected to the first positive displacement unit for rotating the first positive displacement unit;
• at least one reservoir from which the fluid can be drawn by the first positive displacement unit when operating in its pumping mode and to which the fluid can be returned by the first positive displacement unit when operating in its motoring mode;
• a first conduit system containing at least a first hydraulic valve of each of the sets of hydraulic valves for selectively fluidically connecting the first positive displacement unit to either or both of the first and second hydraulic actuators, the first conduit system continuously fluidically connecting the first hydraulic valves;
• a second conduit system containing at least a second hydraulic valve of each of the sets of hydraulic valves for selectively fluidically connecting the first and second hydraulic actuators to the reservoir, the second conduit system continuously fluidically connecting the second hydraulic valves;
• a third conduit system containing at least a third hydraulic valve of each of the sets of hydraulic valves, the third conduit system continuously fluidically connecting the third hydraulic valves and being adapted to transfer the fluid between the first and second hydraulic actuators;
• a hydraulic transformer comprising at least two ports between the first and third conduit systems where pressure and flow can be exchanged at different levels;
• first valve means for selectively fluidically isolating the first conduit system from the third conduit system and selectively fluidically connecting the first conduit system to the third conduit system;
• and
• second valve means for selectively fluidically isolating the second conduit system from the third conduit system and selectively fluidically connecting the second conduit system to the third conduit system;
• wherein the hydraulic system is operable to:
• supplement a resistive load generated by the fluid within one of the first and second hydraulic actuators with an assistive load generated by the fluid in the other of the first and second hydraulic actuators by transferring the fluid within the other of the first and second hydraulic actuators to the one of the first and second hydraulic actuators through the third conduit system;
• and
• supplement the resistive load generated by the fluid within the one of the first and second hydraulic actuators by operating the hydraulic transformer.