Pressure relief valve with a reverse free flow configuration integrated therewith

A hydraulic system comprising:

• a source of fluid flow;
• a fluid reservoir;
• a hydraulic actuator having a workport;
• and
• a valve comprising:
• a first port that is fluidly-coupled to the workport of the hydraulic actuator and to the source of fluid flow,
• a second port that is fluidly-coupled to the fluid reservoir,
• a piston configured to block fluid flow from the first port to the second port when the valve is in a closed position,
• a relief mode spring applying a first biasing force on the piston in a distal direction,
• a reverse flow spring applying a second biasing force on the piston in a proximal direction, wherein the reverse flow spring is weaker than the relief mode spring, and
• a pressure setting spring applying a third biasing force on a check element in the distal direction, causing the check element to be seated when the valve is in the closed position, wherein the valve operates in:
• (i) a first mode of operation, wherein fluid received at the first port overcomes the third biasing force of the pressure setting spring, thereby unseating the check element and allowing pilot fluid to flow from the first port to the second port, wherein a first net fluid force is applied on the piston that overcomes the first biasing force of the relief mode spring, causing the piston to move in the proximal direction and relieve fluid flow from the source of fluid flow through the first port to the second port and preclude pressure level of fluid at the workport from exceeding a predetermined pressure setting, and (ii) a second mode of operation, wherein a second net fluid force is applied on the piston that overcomes the second biasing force of the reverse flow spring, causing the piston to move in the distal direction and allow fluid flow from the fluid reservoir through the second port to the first port to preclude cavitation at the workport of the hydraulic actuator.

A method comprising:

• operating a valve in a closed position, wherein the valve comprises (i) a piston configured to block fluid flow from a first port of the valve to a second port of the valve, (ii) a relief mode spring applying a first biasing force on the piston in a distal direction, (iii) a reverse flow spring applying a second biasing force on the piston in a proximal direction, wherein the reverse flow spring is weaker than the relief mode spring, and (iv) a pressure setting spring applying a third biasing force on a check element in the distal direction, causing the check element to be seated when the valve is in the closed position;
• operating the valve in a first mode of operation, wherein fluid received at the first port overcomes the third biasing force of the pressure setting spring, thereby unseating the check element and allowing pilot fluid to flow from the first port to the second port, wherein a first net fluid force is applied on the piston that overcomes the first biasing force of the relief mode spring, causing the piston to move in the proximal direction and allow fluid flow from the first port to the second port;
• and
• operating the valve in a second mode of operation, wherein a second net fluid force is applied on the piston that overcomes the second biasing force of the reverse flow spring, causing the piston to move in the distal direction and allow fluid flow from the second port to the first port.