Combination valve assembly with proportioner override

Claim 2

In a brake system for a vehicle having first and second separate brake sub-systems: brake system pressure loss indicating means for providing a signal in response to pressure loss in either of said brake sub-systems, said indicating means comprising pressure responsive means having first and second opposed effective areas respectively responsive to the pressures in said first and second brake sub-systems, and normally being in a first condition in response to the pressures in both subsystems being approximately normal, and being actuatable to a second condition in response to pressure loss in either but only one sub-system below the approximately normal sub-system pressures, and signal means for providing said signal in response to said pressure responsive means being actuated to said second condition; proportioning valve means in series with one of said first and second brake sub-systems with the input to said proportioning valve means being in fluid pressure communication with one of said first and second opposed effective areas, said proportioning valve means having a normally fixed valve element provided as a part of a vale stem and an annular valve element receiving said valve stem therethrough in radially spaced relation to define an annular flow path and movable relative to said normally fixed valve element to proportion brake apply pressure through said annular valve element in said one brakE sub-system in relation to pressure supplied to the input to said proportioning valve means through said one brake subsystem; and override means actuatable to override said proportioning valve means and including said normally fixed valve element and valve stem of said proportioning valve means and lost motion means, formed of a recessed end of said pressure responsive means and a compression spring and a head on said valve stem in said recessed end and stop means adjacent the opposite end of said annular valve element and normally engaged by the end of said valve stem to define the normally fixed position of said normally fixed valve element, and being actuatable to move said valve stem out of engagement with said stop means and said normally fixed valve element beyond the range of movement of said annular valve element in response to actuation of said pressure responsive means to said second condition in response to pressure loss only in the other of said first and second brake sub-systems, and latching means so holding said pressure responsive means and said valve stem and said normally fixed valve element and subject to normal brake actuating pressures in said first and second sub-systems to release said pressure responsive means for return thereof to said first condition.

Claim 3

The mechanism of claim 1, said override means lost motion means including linkage connecting said pressure responsive means and said proportioning valve means normally fixed valve element and acting to allow a predetermined initial amount of movement of said pressure responsive means while permitting proportioning of pressure when the pressures in said first and second brake sub-systems are approximately normal, and acting only after said predetermined initial amount of movement of said pressure responsive means to an actuating position in response to pressure loss in the other of said first and second brake sub-systems to remove said normally fixed valve element to an open valve position permitting pressure in said one brake system to pass through said proportioning valve means without being proportioned.

Claim 4

The mechanism of claim 1 further comprising metering valve means in series with the other of said first and second brake sub-systems with the input to said metering valve means being in fluid pressure communication with the other of said first and second piston effective areas.

Claim 5

In a brake system for a vehicle having first and second separate brake sub-systems: brake system pressure loss indicating means for providing a signal in response to pressure loss in either of said brake sub-systems, said indicating means comprising pressure responsive means having first and second opposed effective areas respectively responsive to the pressures in said first and second brake sub-systems, and normally being in a first condition in response to the pressures in both sub-systems being approximately normal, and being moved through a predetermined amount of initial movement and therebeyond to a second condition in response to pressure loss in either but only one sub-system below the approximately normal sub-system pressures; and signal means for providing said signal in response to said pressure responsive means being actuated to said second condition; proportioning valve means in series with said second brake sub-system with the input to said proportioning valve means being in fluid pressure communication with said second opposed effective area of said pressure responsive means, said proportioning valve means having a first valve element normally having a fixed position and a second valve element normally movable relative to said first valve element in response to the pressure in said second brake sub-system at the input to said proportioning valve means to proportion pressure at the output of said proportioning valve means; and proportioning valve means override means including said first valve element and lost motion connecting means received within and inclUding one end of said pressure responsive means and connecting said first valve element and said pressure responsive means for movement of said first valve element in a direction away from said second valve element when there is a pressure loss only in said first brake sub-system which is sufficient to move said pressure responsive means beyond said predetermined amount of initial movement to override the proportioning action of said proportioning valve means and permit full transmission of second brake sub-system pressure through said proportioning valve means between said valve elements.

Claim 6

In a brake system for a vehicle having first and second separate brake sub-systems: brake system pressure loss indicating means for providing a signal in response to pressure loss in either of said brake sub-systems, said indicating means comprising pressure responsive means having first and second opposed effective areas respectively responsive to the pressures in said first and second brake sub-systems, and normally being in a first condition in response to the pressures in both sub-systems being approximately normal, and being moved through a predetermined amount of initial movement and therebeyond to a second condition in response to pressure loss in either but only one sub-system below the approximately normal sub-system pressures; and signal means for providing said signal in response to said pressure responsive means being actuated to said second condition; proportioning valve means in series with said second brake sub-system with the input to said proportioning valve means being in fluid pressure communication with said second opposed effective area of said pressure responsive means, said proportioning valve means having a first valve element normally having a fixed position and a second valve element normally movable relative to said first valve element in response to the pressure in said second brake sub-system at the input to said proportioning valve means to proportion pressure at the output of said proportioning valve means; and proportioning valve means override means including said first valve element and lost motion connecting means received within and inclUding one end of said pressure responsive means and connecting said first valve element and said pressure responsive means for movement of said first valve element in a direction away from said second valve element when there is a pressure loss only in said first brake sub-system which is sufficient to move said pressure responsive means beyond said predetermined amount of initial movement to override the proportioning action of said proportioning valve means and permit full transmission of second brake sub-system pressure through said proportioning valve means between said valve elements.

Claim 7

In a brake system for a vehicle having first and second separate brake sub-systems: brake system pressure loss indicating means for providing a signal in response to pressure loss in either of said brake sub-systems, said indicating means comprising pressure responsive means having first and second opposed effective areas respectively responsive to the pressures in said first and second brake sub-systems, and normally being in a first condition in response to the pressures in both sub-systems being approximately normal, and being actuatable to a second condition in response to pressure loss in either but only one sub-system below the approximately normal sub-system pressures, and signal means for providing said signal in response to said pressure responsive means being actuated to said second condition; and proportioning valve means in series with one of said first and second brake sub-systems with the input to said proportioning valve means being in fluid pressure communication with one of said first and second opposed effective areas, said proportioning valve means including a housing having a bore therein, an annular seal support member and an annular valve cap member mounted in said housing bore, said members and said housing bore being substantially axially aligned and said members receiving therein a pressure responsive movable proportioning valve element in reciprocably piloted relation, said annular valve cap member having the piloting surface thereof extending axially a distance greater than the allowable movement of said valve element and said annular seal support member having an axially extending piloting surface of said valve element thereat for bind-free movement of said valve element relative to the piloting surfaces of said members.

Claim 8

In a brake system for a vehicle having first and second separate brake sub-systems: brake system pressure loss indicating means for providing a signal in response to pressure loss in either of said brake sub-systems, said indicating means comprising pressure responsive means having first and second opposed effective areas respectively responsive to the pressures in said first and second brake sub-systems, and normally being in a first condition in response to the pressures in both sub-systems being approximately normal, and being actuatable to a second condition in response to pressure loss in either but only one sub-system below the approximately normal sub-system pressures, and signal means for providing said signal in response to said pressure responsive means being actuated to said second condition; and proportioning valve means in series with one of said first and second brake sub-systems with the input to said proportioning valve means being in fluid pressure communication with one of said first and second opposed effective areas, said proportioning valve means including a housing having a bore therein, an annular seal support member and an annular valve cap member mounted in said housing bore, said members and said housing bore being substantially axially aligned and said members receiving therein a pressure responsive movable proportioning valve element in reciprocably piloted relation, said annular valve cap member having the piloting surface thereof extending axially a distance greater than the allowable movement of said valve element and said annular seal support member having an axially extending piloting surface of said valve element thereat for bind-free movement of said valve element relative to the piloting surfaces of said members.

Claim 9

The mechanism of claim 5, said other annular seal support member piloting surface being coated prior to assembly with a soft metallic plating, of tin, lead or cadmium by way of example, to a radial thickness at least equal to the tolerance allowable for misalignment of said piloting surfaces, said plating being sufficiently soft to wear with a few strokes of said valve element to establish a close alignment and prevent valve binding.

Claim 10

The mechanism of claim 6, said soft metallic plating radial thickness being at least 0.0002 inch.

Claim 11

The mechanism of claim 6, said soft metallic plating radial thickness being in the range of 0.0002 inch to 0.0004 inch.

Claim 12

In a brake system for a vehicle having first and second separate hydraulic brake sub-systems: a proportioning valve assembly in one of said brake sub-systems, said valve assembly having a brake supply pressure inlet and a brake apply pressure outlet and a bore connecting said inlet and said outlet, a proportioning piston mounted in said bore for limited reciprocal movement, a first stop member mounted in said bore and limiting movement of said piston toward said inlet, a second stop member mounted in said bore and limiting movement of said piston toward said outlet, a first proportioning valve element formed on said piston, a second proportioning valve element reciprocably mounted in said bore and having a normally fixed position defined by one of said stop members and cooperating with said first proportioning valve element to control fluid flow and pressure transmittal between said inlet and saiD outlet, first means yieldably urging said piston toward and into engagement with said second stop member, second means yieldably urging said second proportioning valve element toward said first proportioning valve element, a snubbing member on one end of said piston engaging said second stop member, said piston having opposed differential areas with the smaller area being exposed to brake supply pressure at said inlet and the larger area being exposed to brake apply pressure at said outlet to generate a force opposing said first yieldable means and at a predetermined brake supply pressure moving said piston and said first proportioning valve element into proportioning relation with said second proportioning valve element to proportion the brake apply pressure relative to the brake supply pressure, the brake supply pressure decreasing upon brake release and the brake apply pressure then acting on said piston against said first yieldable means to move said piston and said proportioning valve elements toward said inlet and initially decrease said brake apply pressure by piston displacement until said piston engages said first stop member, said second proportioning valve element being moved by the higher brake apply pressure against the decreased brake supply pressure and the force of said second yieldable means to move away from said first proportioning valve element to permit brake fluid flow from said outlet to said inlet and further decrease of brake apply pressure, said first yieldable means then overcoming the force generated by the decreasing brake apply pressure acting on said piston larger differential area and moving said piston away from said first stop member toward said second stop member, said snubbing member engaging said second stop member to cushion the engagement of said piston with said second stop member; and said second yieldable means moving said second proportioning valve element to its normally fixed position spaced from said first proportioning valve element to maintain fluid communication between said inlet and said outlet during the remainder of the brake release cycle and the initial part of the next brake apply cycle.

Claim 13

In a brake system for a vehicle having first and second separate hydraulic brake sub-systems: a proportioning valve assembly in one of said brake sub-systems, said valve assembly having a brake supply pressure inlet and a brake apply pressure outlet and a bore connecting said inlet and said outlet, a proportioning piston mounted in said bore for limited reciprocal movement, a first stop member mounted in said bore and limiting movement of said piston toward said inlet, a second stop member mounted in said bore and limiting movement of said piston toward said outlet, a first proportioning valve element formed on said piston, a second proportioning valve element reciprocably mounted in said bore and having a normally fixed position defined by one of said stop members and cooperating with said first proportioning valve element to control fluid flow and pressure transmittal between said inlet and saiD outlet, first means yieldably urging said piston toward and into engagement with said second stop member, second means yieldably urging said second proportioning valve element toward said first proportioning valve element, a snubbing member on one end of said piston engaging said second stop member, said piston having opposed differential areas with the smaller area being exposed to brake supply pressure at said inlet and the larger area being exposed to brake apply pressure at said outlet to generate a force opposing said first yieldable means and at a predetermined brake supply pressure moving said piston and said first proportioning valve element into proportioning relation with said second proportioning valve element to proportion the brake apply pressure relative to the brake supply pressure, the brake supply pressure decreasing upon brake release and the brake apply pressure then acting on said piston against said first yieldable means to move said piston and said proportioning valve elements toward said inlet and initially decrease said brake apply pressure by piston displacement until said piston engages said first stop member, said second proportioning valve element being moved by the higher brake apply pressure against the decreased brake supply pressure and the force of said second yieldable means to move away from said first proportioning valve element to permit brake fluid flow from said outlet to said inlet and further decrease of brake apply pressure, said first yieldable means then overcoming the force generated by the decreasing brake apply pressure acting on said piston larger differential area and moving said piston away from said first stop member toward said second stop member, said snubbing member engaging said second stop member to cushion the engagement of said piston with said second stop member; and said second yieldable means moving said second proportioning valve element to its normally fixed position spaced from said first proportioning valve element to maintain fluid communication between said inlet and said outlet during the remainder of the brake release cycle and the initial part of the next brake apply cycle.