Three slope proportioning valve

Claim 2

A valve comprising a body having a bore therethrough, an inlet port at one end of said bore and an outlet port at the other end of said bore, a differential area piston slidably disposed in said bore, said differential area piston including differential area means, first valve member means and second valve member means slidably disposed in said bore, one of said valve member means being carried by said differential area piston, said first and second valve member means being separated to maintain free fluid pressure communication between said inlet and outlet ports when the inlet port pressure is less than a first predetermined pressure, said first and second valve member means engaging one another to isolate said inlet port from said outlet port when said first predetermined inlet port pressure is reached and to maintain said isolation until a second predetermined inlet port pressure is reached, said engaged first and second valve member means together providing a displaceable floating barrier to decrease the volume of said outlet port and maintain a first predetermined proportional relation between said inlet port pressure and said outlet port pressure when said inlet port pressure is greater than said first predetermined pressure and less than said second predetermined pressure, said first and second valve member means separating to establish throttled fluid pressure communication between said inlet port and said outlet port when said inlet port pressure reaches said second predetermined pressure to maintain increases in said outlet port pressure in a second predetermined proportional relation to increases in said inlet port pressure when said inlet port pressure exceeds said second predetermined pressure.

Claim 3

A valve comprising a body having a bore therethrough, an inlet port at one end of said bore and an outlet port at the other end of said bore, a differential area piston slidably disposed in said bore, said differential area piston including differential area means, said differential area means including a smaller diameter portion of said differential area piston sealingly engaging one portion of said bore and a larger diameter portion of said differential area piston sealingly engaging another portion of said bore, a first spring biasing said differential area piston to a first position in said bore, a passage extending axially at least partially through said differential area piston establishing open fluid pressure communication between said inlet port and said outlet port when the fluid pressure in said fluid inlet port is less than a first predetermined pressure, an annular valve head on said differential area piston surrounding said passage, a floating valve seat slidably disposed in said bore, a second spring biasing said floating valve seat to a second predetermined position, said differential area piston being movable from said first position to a third position in which said valve head engages said floating valve seat to close said passage and hydraulically isolate said inlet port from said outlet port, said valve head and said floating valve seat maintaining said isolation when said fluid inlet pressure is greater than said first predetermined pressure and less than a second predetermined pressure, said differential area piston and said floating valve seat being movable together from their respective said second and third positions to decrease the volume of said outlet port and maintain a first predetermined proportional relation between increases in said inlet port pressure and increases in said outlet port pressure when said inlet port pressure is greater than said first predetermined pressure and less than said second predetermined pressure by operation of said differential area means, said differential area piston being movable by operation of said differential area means away from said floating valve seat to move said valve head away from said floating valve seat and establish throttled fluid pressure communication between said inlet port and said outlet port through said passage means when said inlet port pressure exceeds said second predetermined pressure, and said differential area means maintaining increases in said inlet port pressure in a second predetermined proportional relation to increases in said outlet port pressure when said inlet port pressure exceeds said second predetermined pressure.

Claim 4

A valve comprising a body having a bore therethrough, an inlet port at one end of said bore and an outlet port at the other end of said bore, a differential area piston slidably disposed in said bore, said differential area piston including differential area means, said differential area means including a smaller diameter portion of said differential area piston sealingly engaging one portion of said bore and a larger diameter portion of said differential area piston sealingly engaging another portion of said bore, a first spring biasing said differential area piston to a first position in said bore, a passage extending axially at least partially through said differential area piston establishing open fluid pressure communication between said inlet port and said outlet port when the fluid pressure in said fluid inlet port is less than a first predetermined pressure, an annular valve head on said differential area piston surrounding said passage, a floating valve seat slidably disposed in said bore, a second spring biasing said floating valve seat to a second predetermined position, said differential area piston being movable from said first position to a third position in which said valve head engages said floating valve seat to close said passage and hydraulically isolate said inlet port from said outlet port, said valve head and said floating valve seat maintaining said isolation when said fluid inlet pressure is greater than said first predetermined pressure and less than a second predetermined pressure, said differential area piston and said floating valve seat being movable together from their respective said second and third positions to decrease the volume of said outlet port and maintain a first predetermined proportional relation between increases in said inlet port pressure and increases in said outlet port pressure when said inlet port pressure is greater than said first predetermined pressure and less than said second predetermined pressure by operation of said differential area means, said differential area piston being movable by operation of said differential area means away from said floating valve seat to move said valve head away from said floating valve seat and establish throttled fluid pressure communication between said inlet port and said outlet port through said passage means when said inlet port pressure exceeds said second predetermined pressure, and said differential area means maintaining increases in said inlet port pressure in a second predetermined proportional relation to increases in said outlet port pressure when said inlet port pressure exceeds said second predetermined pressure.

Claim 5

A valve as set forth in claim 2 including stop means in said bore for engaging said floating valve seat and limiting movement of said floating valve seat away from said second position.

Claim 6

A valve as set forth in claim 2 including check valve means for re-establishing open fluid pressure communication between said inlet port and said outlet port when said inlet port pressure decreases from a pressure greater than said first predetermined pressure to a pressure less than said first predetermined pressure.

Claim 7

A valve as set forth in claim 2 wherein said second spring means is a coil spring acting between said differential area piston and said floating valve seat.

Claim 8

A valve as set forth in claim 5 wherein said first spring means is another coil spring having a larger mean spring diameter than said first mentioned coil spring, and said first mentioned coil spring is coaxially disposed within said other coil spring.

Claim 9

A valve comprising a body having a bore therethrough, an inlet port at one end of said bore and an outlet port at the other end of said bore, a differential area piston slidably disposed in said bore, said differential area piston including differential area means, said differential area means including a smaller diameter portion of said differential area piston sealingly engaging one portion of said bore and a larger diameter portion of said differential area piston sealingly engaging another portion of said bore, a first spring biasing sAid differential area piston to a first position in said bore, a first passage extending axially at least partially through said differential area piston, an annular valve head on said differential area piston surrounding said first passage, a floating valve seat slidably disposed in said bore, said floating valve seat including a larger diameter seat portion and an axially extending smaller diameter stem portion, said smaller diameter stem portion being slidably disposed in said first passage for guiding movement of said floating valve seat, a second spring biasing said floating valve seat to a second predetermined position, a second passage extending axially at least partially through said floating valve seat establishing open fluid pressure communication between said inlet port and said outlet port when the fluid pressure in said fluid inlet port is less than a first predetermined pressure, said differential area piston being movable from said first position to a third position in which said valve head engages said seat portion to close said second passage and hydraulically isolate said inlet port from said outlet port when said inlet port pressure is greater than said first predetermined pressure, said valve head and said seat portion maintaining said isolation when said inlet port pressure is greater than said first predetermined pressure and less than a second predetermined pressure, said differential area piston and said floating valve seat being movable together from their respective said second and third positions to decrease the volume of said outlet port and maintain a first predetermined proportional relation between increases in said inlet port pressure and increases in said outlet port pressure when said inlet port pressure is greater than said first predetermined pressure and less than said second predetermined pressure by operation of said differential area means, said differential area piston being movable by operation of said differential area means away from said seat portion to move said valve head away from said valve member and establish throttled fluid pressure communication between said inlet port and said outlet port through said second passage when said inlet port pressure exceeds said second predetermined pressure, and said differential area means maintaining increases in said inlet port pressure in a second predetermined proportional relation to increases in said outlet port pressure when said inlet port pressure exceeds said second predetermined pressure.

Claim 10

A valve comprising a body having a bore therethrough, an inlet port at one end of said bore and an outlet port at the other end of said bore, a differential area piston slidably disposed in said bore, said differential area piston including differential area means, said differential area means including a smaller diameter portion of said differential area piston sealingly engaging one portion of said bore and a larger diameter portion of said differential area piston sealingly engaging another portion of said bore, a first spring biasing sAid differential area piston to a first position in said bore, a first passage extending axially at least partially through said differential area piston, an annular valve head on said differential area piston surrounding said first passage, a floating valve seat slidably disposed in said bore, said floating valve seat including a larger diameter seat portion and an axially extending smaller diameter stem portion, said smaller diameter stem portion being slidably disposed in said first passage for guiding movement of said floating valve seat, a second spring biasing said floating valve seat to a second predetermined position, a second passage extending axially at least partially through said floating valve seat establishing open fluid pressure communication between said inlet port and said outlet port when the fluid pressure in said fluid inlet port is less than a first predetermined pressure, said differential area piston being movable from said first position to a third position in which said valve head engages said seat portion to close said second passage and hydraulically isolate said inlet port from said outlet port when said inlet port pressure is greater than said first predetermined pressure, said valve head and said seat portion maintaining said isolation when said inlet port pressure is greater than said first predetermined pressure and less than a second predetermined pressure, said differential area piston and said floating valve seat being movable together from their respective said second and third positions to decrease the volume of said outlet port and maintain a first predetermined proportional relation between increases in said inlet port pressure and increases in said outlet port pressure when said inlet port pressure is greater than said first predetermined pressure and less than said second predetermined pressure by operation of said differential area means, said differential area piston being movable by operation of said differential area means away from said seat portion to move said valve head away from said valve member and establish throttled fluid pressure communication between said inlet port and said outlet port through said second passage when said inlet port pressure exceeds said second predetermined pressure, and said differential area means maintaining increases in said inlet port pressure in a second predetermined proportional relation to increases in said outlet port pressure when said inlet port pressure exceeds said second predetermined pressure.