Back to results
US 4,071,283 AGranted
Master and slave break boosters for front and rear wheel brakes with wheel lock control
AssigneeGeneral Motors Corporation
InventorRobert M. Van House
Life of this patent
Estimating the term…
Abstract
A brake booster and master cylinder assembly operates the front wheels of a vehicle and a slave booster and master cylinder assembly operates the rear wheels of the vehicle. A solenoid controlled valve in a conduit connecting the variable pressure sides of the booster units normally permits free air passage. When energized for wheel lock control purposes, it blocks the flow of air between the two boosters, admitting engine vacuum to the high pressure side of the slave booster. This decreases rear brake actuating pressure under control of a logic system.
Claims2
A vehicle brake system having front and rear brakes with wheel lock control of the rear brakes, said system comprising:
- a source of vacuum;
- a master brake booster and master cylinder assembly operable by a vehicle operator and connected to actuate the vehicle front brakes, the booster being a vacuum suspended booster having a vacuum chamber and a variable pressure chamber and pressures therein, the pressure in the variable pressure chamber being controlled during assembly actuation in accordance with operator operation of the booster;
- a slave brake booster and master cylinder assembly connected to actuate the vehicle rear brakes, the slave booster being a vacuum suspended booster having a vacuum chamber and a variable pressure chamber and being capable of delivering a boost force to the slave master cylinder;
- first conduit means connecting said master brake booster vacuum chamber and said slave brake booster vacuum chamber with said vacuum source;
- second conduit means having a solenoid operated valve therein which when de-energized connects said master brake booster variable pressure chamber and said slave brake booster variable pressure chamber, said solenoid operated valve when energized disconnecting the variable pressure chambers and connecting said slave brake booster variable pressure chamber with said first conduit means to impose vacuum therein independently of the operation of said master brake booster and thereby reduce the braking action of the rear brakes by reducing the boost force of said slave brake booster;
- and wheel lock control logic and incipient wheel lock sensing means for the vehicle rear brakes connected to energize and de-energize said solenoid operated valve, thereby selectively cycling said valve to generate a pressure in said slave brake booster variable pressure chamber from vacuum and the variable pressure in said master brake booster variable pressure chamber, said pressure so generated causing a lesser pressure differential actuating said slave brake booster than the pressure differential actuating said master brake booster and tending to prevent rear wheel lock due to lesser brake energization by said slave brake booster and master cylinder assembly.
3 more elements
A vehicle brake system comprising:
- a first vehicle operator controlled and pressure actuated brake booster for a first set of wheel brakes and having a pair of pressure chambers, one chamber being at a substantially constant pressure and the other chamber being subject to a variable control pressure;
- a second pressure actuated brake booster for a second set of wheel brakes and having a pair of pressue chambers, one chamber being at a substantially constant pressure and the other chamber being subject to a variable control pressure;
- first and second conduit means, said first conduit means normally pressure connecting said substantially constant pressure chambers of said first and second boosters and said second conduit means normally pressure connecting said variable control pressure chambers of said first and second boosters to provide slave operation of said second booster in accordance with vehicle operator controlled actuation of said first booster;
- control means in said conduit means, said control means including a control valve having a normally open pressure inlet and an open pressure outlet and a normally closed pressure inlet, said normally open pressure inlet and outlet being connected in said second conduit means fluidly intermediate said variable control pressure chambers and said normally closed pressure inlet being fluid connected to said first conduit means fluidly intermediate said substantially constant pressure chambers, said valve being movable to open said closed pressure inlet and close said open pressure inlet, thereby selectively connecting the second booster pair of pressure chambers in fluid communication with each other while disconnecting said first booster variable control pressure chamber from said second booster variable control pressure chamber to deactuate said second booster;
- and a wheel lock control logic connected to operate said control means when incipient wheel lock exists at the wheels braked by the second set of wheel brakes to deactuate said second booster and selectively cycle said valve to generate a variable pressure in said second booster variable control pressure chamber from pressures in said first booster pressure chambers.
2 more elements
Dependencies are inferred from the claim text.