Combination warning switch and proportioning valve

Claim 2

In a vehicular braking system having first and second hydraulic circuits; a housing having a bore therein; piston means movable in said bore, said piston means dividing said bore into first and second chambers, said first and second chambers being in fluid communication with said first and second hydraulic circuits, respectively; an annular seal circumscribing said bore in one of said chambers, one end of said piston means cooperating with said seal during increasing fluid pressure in said chambers to meter the flow of fluid past the seal and establish a lower level of fluid pressure on one side of the seal than exists on the other side of the seal, said piston means being responsive to a predetermined pressure differential between said first and second chambers to shift said one end away from said seal to permit unrestricted flow of fluid through said one chamber; and reseT means operatively connected to said piston means for urging the one end of the piston means into operative engagement with the seal upon equalization of fluid pressure in said first and second chambers.

Claim 3

The invention of claim 1; and a warning switch carried by the housing; said piston means actuating said warning switch when the piston means is shifted due to said pressure differential between said first and second chambers.

Claim 4

The invention of claim 2: said warning switch including a plunger projecting into said bore; said piston means having camming surfaces formed thereon for engagement with said plunger for shifting the latter to actuate said warning switch.

Claim 5

The invention of claim 1: said bore being stepped to present larger and smaller diameter portions with a shoulder therebetween; said reset means being a sleeve having larger and smaller outer diameter portions presenting a shoulder therebetween; said sleeve cooperating with said piston means to define a larger area against which fluid pressure in one of the chambers acts and a smaller area against which fluid pressure in the other chamber acts whereby the shoulder on the sleeve is urged into engagement with the shoulder on the housing when equal pressures are introduced into each of said chambers.

Claim 6

The invention of claim 1: said one end of said piston means extending through the opening defined by said annular seal and having a smaller diameter portion defining a flow path between the outer circumferential surface of said smaller portion and the inner circumferential surface of said seal and a larger diameter portion cooperating with the transversely extending surface of the seal to meter flow of fluid through said flow path.

Claim 7

The invention of claim 5: said annular seal yielding to permit said larger diameter portion of the piston means to pass through the opening defined by the annular seal when the piston means is shifted due to said pressure differential between the first and second chambers, whereby unrestricted flow of fluid is permitted through said opening after the piston is shifted.

Claim 8

The invention of claim 5; and resilient means operatively connected to said piston means yieldably urging said larger diameter portion out of engagement with the transverse surface of said seal.

Claim 9

A proportioning valve for regulating fluid flow from a pressure source to separate first and second circuits going to the front and rear brakes of a vehicular braking system in response to an operational pressure differential, said proportioning valve comprising: a housing having a bore therein with first and second inlet ports connected to said pressure source, a first outlet port connected to the front brakes and a second outlet port connected to the rear brakes; piston means for dividing said bore into first and second chambers, said first inlet and outlet ports being connected to said first chamber, said second inlet port being connected to said second chamber, said piston means having a single shaft with a first head located in the first chamber and a second head located in the second chamber, said first head being smaller in diameter than said second head; annular seal means located in said second chamber for separating said second inlet port from said second outlet port, said fluid under pressure communicated to the first and second chamber acting on said first and second heads of the piston means, said second head being moved toward said seal means to meter the flow of fluid from said pressure source upon the development of a differential pressure force between said first and second heads, said second head shifting away from said seal means upon the development of a predetermined pressure force to permit unrestricted flow through said second chamber for activation of said rear brakes; and reset means operatively connected to said piston means for urging said second head into operative engagement with said seal means upon equaLization of pressure in said first and second chambers from said pressure source.

Claim 10

A proportioning valve for regulating fluid flow from a pressure source to separate first and second circuits going to the front and rear brakes of a vehicular braking system in response to an operational pressure differential, said proportioning valve comprising: a housing having a bore therein with first and second inlet ports connected to said pressure source, a first outlet port connected to the front brakes and a second outlet port connected to the rear brakes; piston means for dividing said bore into first and second chambers, said first inlet and outlet ports being connected to said first chamber, said second inlet port being connected to said second chamber, said piston means having a single shaft with a first head located in the first chamber and a second head located in the second chamber, said first head being smaller in diameter than said second head; annular seal means located in said second chamber for separating said second inlet port from said second outlet port, said fluid under pressure communicated to the first and second chamber acting on said first and second heads of the piston means, said second head being moved toward said seal means to meter the flow of fluid from said pressure source upon the development of a differential pressure force between said first and second heads, said second head shifting away from said seal means upon the development of a predetermined pressure force to permit unrestricted flow through said second chamber for activation of said rear brakes; and reset means operatively connected to said piston means for urging said second head into operative engagement with said seal means upon equaLization of pressure in said first and second chambers from said pressure source.

Claim 11

The invention of claim 8; and a warning switch carried by the housing; said piston means actuating said warning switch when the single shaft of said piston means is shifted a predetermined distance due to said pressure differential between said first and second chambers.

Claim 12

The invention of claim 9: said warning switch including a plunger projecting into said bore; said single shaft having camming surfaces formed thereon adjacent a small diameter portion for engagement with said plunger for shifting the latter to actuate said warning switch.

Claim 13

The invention of claim 8: said bore being stepped to present larger and smaller diameter portions with a shoulder therebetween; said reset means being a sleeve having larger and smaller outer diameter portions presenting a shoulder therebetween; said sleeve cooperating with said piston means to define a larger area against which fluid pressure in one of the chambers acts and a smaller area against which fluid pressure in the other chamber acts whereby the shoulder on the sleeve is urged into engagement with the shoulder on the housing when equal pressures are introduced into each of said chambers.