Remotely-actuated dual-pressure relief valve

A dual-pressure relief valve assembly comprising, in combination:

• an actuating assembly comprising:
• a pilot piston housing forming a pilot piston cylinder;
• a pilot piston movable within the pilot piston cylinder of the pilot piston housing;
• a relief valve comprising:
• a relief valve housing secured to the pilot piston housing and forming a first bore, a relief valve seat along the first bore, and a second bore;
• a relief valve piston movable within the first bore of the relief valve housing and carrying a relief valve member configured to close the relief valve seat when engaging the relief valve seat;
• and
• a first resilient spring acting between the pilot piston and the relief valve piston to bias the relief valve member toward the relief valve seat;
• wherein the first bore is a first blind bore and the relief valve seat is provided near a blind end of the first blind bore, and wherein the second bore is a second blind bore coaxial with the first blind bore and facing opposite the first blind bore;
• wherein the pilot piston cylinder is provided with a pilot port to selectively engage the pilot piston with a predetermined pilot pressure to selectively move the pilot piston toward the first resilient spring and the relief valve piston;
• wherein the first resilient spring biases the relief valve member into engagement with the relief valve seat with a first predetermined relief pressure when the predetermined pilot pressure is not applied to the pilot piston and with a second predetermined relief pressure when the predetermined pilot pressure is applied to the pilot piston;
• wherein the second predetermined relief pressure is larger than the first predetermined relief pressure;
• and
• a check valve comprising:
• a check valve member movable within the second blind bore;
• and
• at least one second resilient spring acting between the relief valve housing and the check valve member to bias the check valve member away from the relief valve housing.

A dual-pressure relief valve assembly comprising, in combination:

• an actuating assembly comprising:
• a pilot piston housing forming a pilot piston cylinder;
• a pilot piston movable within the pilot piston cylinder of the pilot piston housing;
• a relief valve comprising:
• a relief valve housing secured to the pilot piston housing and forming a first blind bore, a relief valve seat along the first bore near a blind end of the first blind bore, and a second blind bore;
• wherein the second blind bore is coaxial with the first blind bore and facing opposite the first blind bore;
• a relief valve piston movable within the first bore of the relief valve housing and carrying a relief valve member configured to close the relief valve seat when engaging the relief valve seat;
• and
• a first resilient spring acting between the pilot piston and the relief valve piston to bias the relief valve member toward the relief valve seat;
• wherein the pilot piston cylinder is provided with a pilot port to selectively engage the pilot piston with a predetermined pilot pressure to selectively move the pilot piston toward the first resilient spring and the relief valve piston;
• wherein the first resilient spring biases the relief valve member into engagement with the relief valve seat with a first predetermined relief pressure when the predetermined pilot pressure is not applied to the pilot piston and with a second predetermined relief pressure when the predetermined pilot pressure is applied to the pilot piston;
• wherein the second predetermined relief pressure is larger than the first predetermined relief pressure;
• and
• a check valve comprising:
• a check valve member movable within the second blind bore;
• at least one second resilient spring acting between a blind end of the second blind bore and the check valve member to bias the check valve member away from the blind end of the second blind bore;
• and
• a check valve retainer secured within the second blind bore and forming an outer limit for movement of the check valve member within the second blind bore.