Fluid control valve apparatus

A fluid control valve apparatus including:

• logic valve means comprising:
• a valve housing;
• a first valve chamber defined in the valve housing;
• a valve body arranged in the first valve chamber for fluidtight movement in an axial direction, the valve body including opposite end portions and a conical surface portion;
• a valve seat adapted to be brought into fluidtight sealing contact with the conical surface portion of the valve body when the valve body moves in a valve closing direction;
• a first hydraulic fluid chamber and a second hydraulic fluid chamber defined in the valve housing and adapted to be brought into communication with each other when the conical surface portion of the valve body is released from contact with the valve seat and brought out of communication with each other when the conical surface portion of the valve body is brought into contact with the valve seat;
• and
• a first pilot chamber defined in the valve housing adjacent one end portion of the valve body and operative to force the valve body to move in the valve closing direction by a first pilot pressure signal received therein;
• wherein the logic valve means further comprises:
• a second valve chamber defined in the valve housing;
• a valve body extension formed by extending the other end portion of the valve body through the first hydraulic fluid chamber and arranged in the second valve chamber for fluidtight movement in an axial direction;
• a second pilot chamber defined in the valve housing adjacent an end of the valve body extension and operative to force the valve body extension to move in a valve opening direction by a second pilot pressure signal received therein;
• logic valve control means comprising reference pressure setting means for applying a substantially constant reference pressure at all times to the first pilot chamber of the logic valve means as the first pilot pressure signal;
• switch means for applying to the second pilot chamber of the logic valve means as a second pilot pressure signal a first predetermined pressure higher than the reference pressure when the valve is to be opened and applying to the second pilot chamber of the logic valve means as a second pilot pressure signal a second predetermined pressure lower than the reference pressure when the valve is to be closed;
• and wherein said switch means comprises a first on-off valve connected to a pilot pump, and a second on-off valve connected to a reservoir, said first and second on-off valves are connected to the second pilot chamber of the logic valve means in parallel with each other.

A fluid control valve apparatus including:

• logic valve means comprising:
• a valve housing;
• a first valve chamber defined in the valve housing;
• a valve body arranged in the first valve chamber for fluidtight movement in an axial direction, the valve body including opposite end portions and a conical surface portion;
• a substantially circular valve seat adapted to be brought into fluidtight sealing contact with the conical surface portion of the valve body when the valve body moves in a valve closing direction;
• a first hydraulic fluid chamber and a second hydraulic fluid chamber defined in the valve housing and adapted to be brought into communication with each other when the conical surface portion of the valve body is released from contact with the valve seat and brought out of communication with each other when the conical surface portion of the valve body is brought into contact with the valve seat;
• and
• a first pilot chamber defined in the valve housing adjacent one end portion of the valve body and operative to force the valve body to move in the valve closing direction by a first portion pressure signal received therein;
• wherein the logic valve means further comprises:
• a second valve chamber defined in the valve housing;
• a valve body extension formed by extending the other end portion of the valve body through the first hydraulic fluid chamber and arranged in the second valve chamber for fluidtight movement in an axial direction;
• a second pilot chamber defined in the valve housing adjacent an end of the valve body extension and operative to force the valve body extension to move in a valve opening direction by a second pilot pressure signal received therein;
• the first and second pilot chamber connected to independently controlled hydraulic pressure sources;
• and
• wherein said logic valve means further comprises a rod means secured to the valve housing and extending in an axial direction to the first pilot chamber, a further chamber defined in said valve body and receiving said rod means for reciprocatory sliding movement, said further chamber defining a pressure regulating chamber therein between a wall surface thereof and an end portion of said rod means, and a communicating duct formed in the valve body and communicating said pressure regulating chamber with said first hydraulic fluid chamber, and wherein said second valve chamber has a diameter less than the diameter of the valve seat and said rod means has a diameter set at a value such that a square of the diameter is substantially equal to a difference between a square of the diameter of the valve seat and the square of the diameter of the second valve chamber multiplied by .pi..