Proportional pressure control valve

A proportional pressure control valve installed within a fluid system comprising:

• a cage which extends in an axial direction and in a radial direction and includes a wall having an inner surface and an outer surface which define a thickness dimension therebetween, and the wall having formed therethrough a pump port opening in fluid communication with a pump port of the system for receiving fluid under pressure, a clutch port opening in fluid communication with a clutch port of the system for supplying such fluid to an actuator, and a tank port opening in fluid communication with a tank port of the system for returning such fluid to a tank;
• a spool received within the cage to be moveable axially relative to the cage for controlling fluid flow between the clutch port opening and the pump and tank port openings, the spool having an inner surface and an outer surface which define a thickness dimension therebetween, and a feedback pressure surface responsive to an applied feedback fluid pressure urging the spool to move axially relative to the cage in a first direction towards a first position allowing fluid flow between the clutch port and the tank port;
• a feedback pressure chamber defined within the cage for developing the feedback fluid pressure on the feedback pressure surface of the spool;
• and
• a clutch port pressure feedback passage coupling the clutch port in fluid communication with the feedback pressure chamber for admitting a fluid flow from the clutch port into the feedback pressure chamber to develop the feedback fluid pressure on the feedback pressure surface of the spool, the clutch port pressure feedback passage being formed within the thickness dimension of the cage wall to extend generally axially intermediate a first port in fluid communication with the control pressure chamber and a second port in fluid communication with the clutch port of the system.

A method of operating a proportional pressure control valve installed within a fluid system, the method comprising the steps of:

• (a) providing the control valve as comprising:
• a cage which extends in an axial direction and in a radial direction and includes a wall having an inner surface and an outer surface which define a thickness dimension therebetween, and the wall having therethrough a pump port opening in fluid communication with a pump port of the system, a clutch port opening in fluid communication with a clutch port of the system, and a tank port opening in fluid communication with a tank port of the system;
• a spool received within the cage to be moveable axially relative to the cage for controlling fluid flow between the clutch port opening and the pump and tank port openings, the spool having an inner surface and an outer surface which define a thickness dimension therebetween, and a feedback pressure surface;
• a feedback pressure chamber defined within the cage;
• and
• a clutch port pressure feedback passage coupling the clutch port in fluid communication with the feedback pressure chamber, the clutch port pressure feedback passage being formed within the thickness dimension of the cage wall to extend generally axially intermediate a first port in fluid communication with the control pressure chamber and a second port in fluid communication with the clutch port of the system;
• (b) receiving fluid under pressure from the pump port through the pump port opening;
• and
• (c) admitting a flow of the fluid under pressure through the a clutch port pressure feedback passage into the feedback pressure chamber to develop a feedback fluid pressure on the feedback pressure surface of the spool urging the spool to move axially relative to the cage in a first direction towards a first position allowing fluid flow between the clutch port and the tank port.