Shuttle valve for hydraulic brake booster with emergency fluid supply

Claim 2

In a vehicle hydraulic system having a primary hydraulic circuit with a primary pressure source, a second hydraulic circuit with a secondary pressure source, and means for sensing a malfunction in said primary pressure source and actuating said secondary pressure source, a brake booster in fluid communication with each of said circuits comprising: a housing having an inlet and outlet communicated with said primary hydraulic circuit and a pressure chamber; a piston slidably mounted in said pressure chamber; first valve means for controlling fluid communication into said pressure chamber for shifting said piston; second valve means controlling fluid communication between the inlet, the outlet, and the first valve means; said second valve means being operable to terminate fluid communication between the inlet, the outlet, and the first valve means and initiating fluid communication between the first valve means and the secondary pressure source upon actuation of the latter by said sensing means; a bore communicating the inlet with the outlet; said second valve means being a spool valve slidably mounted in said bore and shiftable from a first position permitting substantially uninhibited flow of fluid between the inlet and outlet to a secOnd position upon opening of the first valve means; said spool valve in second position restricting flow of fluid between the inlet and outlet to increase the pressure level in said bore; and passage means communicating said bore with the pressure chamber, said first valve means being mounted in said passage means.

Claim 3

In a vehicle hydraulic system having a primary hydraulic circuit with a primary pressure source, a secondary hydraulic circuit with a secondary pressure source, and means for sensing a malfunction in said primary pressure source and actuating said secondary pressure source, a brake booster in fluid communication with each of said circuits comprising; a housing having an inlet and outlet communicated with said primary hydraulic circuit and pressure chamber; a piston slidably mounted in said pressure chamber; first valve means for controlling fluid communication into said pressure chamber for shifting said piston; second valve means controlling fluid communication between the inlet, the outlet, and the first valve means; said second valve means being operable to terminate fluid communication between the inlet, the outlet, and the first valve means and initiating fluid communication between the first vale means and the secondary pressure source upon actuation of the latter by said sensing means; a bore communicating the inlet with the outlet; passage means communicating said bore with said pressure chamber; said first valve means controlling flow of fluid through said passage means; said second valve means being slidably mounted in said bore and shiftable from a first position permitting substantially unrestricted flow of fluid in said primary hydraulic circuit to a second position restricting flow of fluid therethrough to force pressurized fluid into said passage means, said secondary pressure source forcing said second valve means to a third position terminating fluid communication between said primary hydraulic system and said passage means and initiating fluid communication between said secondary hydraulic circuit and said passage means.

Claim 4

In a vehicle hydraulic system having a primary hydraulic circuit with a primary pressure source, a secondary hydraulic circuit with a secondary pressure source, and means for sensing a malfunction in said primary pressure source and actuating said secondary pressure source, a brake booster in fluid communication with each of said circuits comprising; a housing having an inlet and outlet communicated with said primary hydraulic circuit and pressure chamber; a piston slidably mounted in said pressure chamber; first valve means for controlling fluid communication into said pressure chamber for shifting said piston; second valve means controlling fluid communication between the inlet, the outlet, and the first valve means; said second valve means being operable to terminate fluid communication between the inlet, the outlet, and the first valve means and initiating fluid communication between the first vale means and the secondary pressure source upon actuation of the latter by said sensing means; a bore communicating the inlet with the outlet; passage means communicating said bore with said pressure chamber; said first valve means controlling flow of fluid through said passage means; said second valve means being slidably mounted in said bore and shiftable from a first position permitting substantially unrestricted flow of fluid in said primary hydraulic circuit to a second position restricting flow of fluid therethrough to force pressurized fluid into said passage means, said secondary pressure source forcing said second valve means to a third position terminating fluid communication between said primary hydraulic system and said passage means and initiating fluid communication between said secondary hydraulic circuit and said passage means.

Claim 5

The invention of claim 2: said second valve means being a spool valve slidably mounted in said bore, the end of the spool cooperating with the end of the bore to define a variable-volume chamber therebetween; said second hydraulic circuit being communicated into said variable volume chamber to permit fluid pressure from said secondary source to act against the end of said spool valve to urge the latter toward said third position when said secondary source is actuated.

Claim 6

The invention of claim 3; and conduit means communicating said variable volume chamber with said passage means; said spool valve being operable to initiate fluid communication through said conduit means when the spool valve is disposed in said third position, said spool valve terminating fluid communication through said conduit means when the spool valve is shifted away from said third position.

Claim 7

The invention of claim 2: said piston dividing said pressure chamber into a high pressure section and a low pressure section between opposite ends of the housing and corresponding ends of the piston; said low pressure section being vented to a fluid reservoir; said passage means communicating with said high pressure section; other passage means communicating said high pressure section to said low pressure section; and operator-actuated means for closing said other passage means and thereafter opening said first valve means to admit pressurized fluid into said high pressure section for shifting said piston.

Claim 8

The invention of claim 5; and an orifice extending through said piston communicating said passage means to said high pressure section to provide a flow path between the inlet and the reservoir through the pressure chamber when the brakes of the vehicle are released.

Claim 9

The invention of claim 6: said second valve means being a spool valve slIdably mounted in said bore, one end of said spool valve cooperating with a corresponding end of the bore to define a variable volume cavity therebetween; said inlet port being communicated with said variable volume cavity therebetween; said inlet port being communicated with said variable volume cavity; and channel means extending through the spool valve communicating said variable cavity with said outlet and with said passage means; said spool valve being shifted to said second position by fluid pressure in said variable volume cavity acting upon said one end of the spool valve upon increase of the fluid pressure level communicated to said variable volume cavity from said high pressure section when the operator-operated means prevents flow of fluid through said other passage means when a brake application is effected.

Claim 10

The invention of claim 7: said first valve means being mounted with said piston; said passage means including an annular compartment defined between the outer circumferential surface of the piston and the wall of the bore, a first passage communicating the annular compartment with said bore, and a second passage within said piston communicating said annular compartment with said high pressure section; said first valve means being mounted within said second passage.