System and method for a pilot shifted regeneration valve

1 . A method for recycling fluid from a first side of a double acting hydraulic cylinder for use on a second side of the cylinder to accelerate piston movement, the method comprising:

sending power to a normally closed solenoid valve of a pilot-shifted regeneration valve assembly to enable a regeneration function;

sending power to a proportional pressure reducing valve thereby sending pilot pressure both to a spool of a directional control valve and a piloted two position three-way valve of the pilot-shifted regeneration valve assembly;

the piloted two position three-way valve remaining in position one until pilot pressure from the proportional pressure reducing valve overcomes a spring force of a spring on the opposing side of the piloted two-position three-way valve;

with the piloted two position three-way valve in position one, fluid exiting a retract side of the hydraulic cylinder passes through the directional control valve to return to a fluid reservoir;

once the pilot pressure is sufficient to shift the piloted two position three-way valve to position two, the fluid exiting the retract side of the hydraulic cylinder is forced to an extend side and an effective area of the hydraulic cylinder is reduced to a rod area with both the extend and retract side of the piston being pressurized equally;

during a transition phase from position one to position two, the fluid exiting the retract side of the hydraulic cylinder is temporarily blocked from returning through both the directional control valve and the extend side of the hydraulic cylinder;

operating pressure of the fluid on the retract side of the cylinder is limited to a safe level by a relief valve connected to a retract flow path;

when no longer requiring rapid extension of the piston using the pilot shifted regeneration valve assembly, the electrical power supplied to the normally closed solenoid valve is turned off by the operator causing the pilot pressure opposing the spring in the piloted two-position three-way valve to be drained through a second orifice to a drain port and the two-position three-way valve smoothly transitions to position one resulting in a more forceful but slower movement of the piston;

equipping the pilot shifted regeneration valve assembly with a pressure transducer to monitor the pressure in the extension side of the hydraulic cylinder;

sensing by the pressure transducer to assess whether fluid pressure is higher than a pre-established limit for the fluid in a regenerative circuit;

terminating electrical power to the normally closed solenoid valve to shift the two-position three-way valve to position one if the fluid pressure is higher than the predetermined limit of the pressure transducer; and

allowing the fluid from the retract side of the cylinder to return to the hydraulic reservoir and to the extend side of the cylinder to extend the piston with maximum force.

2 . The method of claim 1 , wherein the first side of a double acting hydraulic cylinder is the retraction side, and the second side is the extension side of the cylinder.

3 . The method of claim 1 , wherein a first orifice regulates the pressure coming directly from the proportional pressure reducing pilot control valve and controls the amount of pressure entering the system.

4 . The method of claim 3 , wherein the second orifice disposed downstream from the first orifice, controls the flow of fluid that is drained from the pilot path of the two-position three-way valve.

5 . The method of claim 4 , wherein the fluid returned from the retract side of the cylinder combined with the pump flow is directed into the extension side of the cylinder, which extends the piston more quickly by utilizing both sources of hydraulic fluid.

6 . A system for recycling fluid from a first side of a double acting hydraulic cylinder for use on a second side of the cylinder to accelerate piston movement; the system comprising:

a normally closed solenoid valve operable to enable a regeneration function;

a proportional pressure reducing valve operable to send pilot pressure to

(i) a spool of a directional control valve and

(ii) a piloted two-position three-way valve, wherein the piloted two position three-way valve remains in a position one until pilot pressure from the proportional pressure reducing valve overcomes a spring force of a spring on the opposing side of the piloted two position three-way valve, with the piloted two-position three-way valve in position one, fluid exiting a retract side of the hydraulic cylinder passes through the directional control valve to a fluid reservoir and once the pilot pressure is sufficient to shift the piloted two-position three-way valve to a position two, the fluid exiting the retract side of the hydraulic cylinder is forced to an extend side and an effective area of the hydraulic cylinder is reduced to a rod area with both the extend and retract side of the piston being pressurized equally, wherein during a transition phase from position one to position two, the fluid exiting the retract side of the hydraulic cylinder is temporarily blocked from returning through both the directional control valve and the extend side of the hydraulic cylinder;

a relief valve in the pilot shifted regeneration valve assembly for maintaining an operating pressure of the fluid on the retract side of the cylinder at a safe level, the relief valve being fluidly connected to a retract flow path, such that when the operator no longer seeks to rapidly extend the piston using the pilot-shifted regeneration valve assembly the power supplied to the normally closed solenoid valve is turned off at which point the pilot pressure opposing the spring in the piloted two-position three-way valve is drained;

a second orifice to drain the pilot pressure opposing the spring in the piloted two position three-way valve to a drain port, wherein the two-position three-way valve smoothly transitions to position one resulting in a more forceful but slower extension of the piston; and

a pressure transducer to determine if the pressure in the extension side of the hydraulic cylinder is higher than a predetermined limit of a regenerative circuit, wherein the termination of electrical power to the normally closed solenoid valve to shift the two-position three-way valve to position one if the fluid pressure is higher than the predetermined limit of the system allowing the fluid from the retract side of the cylinder to return to the hydraulic reservoir and the hydraulic cylinder to extend with maximum force.

7 . The system of claim 6 , wherein a first orifice is operable to control the pressure at the regeneration valve and prevent pressure spikes or overshoot when the regeneration valve shifts.

8 . The system of claim 7 , wherein the first orifice decreases the pressure of hydraulic fluid entering the two-position-three-way valve.

9 . The system of claim 8 , wherein the efficiency of the first orifice to decrease pressure and facilitate flow of the fluid depends upon an orifice geometry and an edge sharpness of the first orifice.

10 . The system of claim 9 , wherein a discharge coefficient for the first orifice ranges from 0.6 to 0.9 including the upper and lower bounds.

11 . The system of claim 10 , wherein the geometry of the first orifice is at least one of sharp edged, conical, rounded, beveled, chamfered edges or comprises long or short tubes and a length to diameter ratio of less than one.

12 . The system of claim 6 , wherein a second orifice drains to a port the pilot pressure opposing the spring in the piloted two position three-way valve.

13 . The system of claim 12 , wherein the drain port allows the two-position three-way valve to smoothly transition to position one resulting in a more forceful but slower movement of the piston.

14 . The system of claim 13 , wherein the second orifice regulates the flow of pilot pressure fluid once the normally closed solenoid valve is closed.

15 . The system of claim 14 , wherein the second orifice regulates flow exiting the valve assembly and is used to control actuator speed and maintain a certain pressure on the actuator side to smooth transitions or hold a position.

16 . The system of claim 15 , wherein the discharge coefficient of the second orifice ranges from 0.6 to 0.9.

17 . The system of claim 6 , wherein the orifice geometry is at least one of sharp edged, conical, rounded, beveled, chamfered edges or comprise long or short tubes and a length to diameter ratio of greater than one.