Hydraulic anti-skid braking systems for vehicles
First Claim
1. An hydraulic anti-skid system for a vehicle comprising a vehicle brake, a supply of operating fluid for applying said brake, skid sensing means for producing a skid signal to modulate the supply of operating fluid from said supply to said brake, a pump having a piston assembly, a drive mechanism for said pump, and means defining a stop chamber, said piston assembly comprising a pump plunger reciprocable in a bore by means of said drive mechanism, a signal piston, a coupling between said signal piston and said pump plunger, and resilient means for urging said pump plunger out of engagement with said drive mechanism, said signal piston having a first area which is exposed to pressure from said supply or from said brake when said brake is applied to urge said signal piston in a direction such that said pump plunger can engage with said drive mechanism, and a dump valve for controlling fluid in said stop chamber to which said piston assembly is exposed at least after said brake has been applied, said dump valve being normally closed to trap fluid in said stop chamber in order to hold said piston assembly in a retracted position in which said pump plunger is disengaged from said drive mechanism, and said dump valve being movable into an open position in response to said skid signal to release fluid from said drive mechanism.
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Accused Products
Abstract
An hydraulic anti-skid system incorporates a pump having a piston assembly. The piston assembly comprises a pump plunger which is reciprocable in a bore of a drive mechanism, a signal piston coupled to the pump plunger, and a spring for urging the pump plunger out of engagement with the drive mechanism. The signal piston has a first area which is exposed to the pressure from a master cylinder or the brake when the brake is applied to urge the signal piston in a direction such that the pump plunger can engage with the drive mechanism. A dump valve is provided for controlling fluid in a stop chamber to which the piston assembly is exposed at least after the brake has been applied. The dump valve is normally closed to trap fluid in the stop chamber in order to hold the piston assembly in a retracted position in which the pump plunger is disengaged from the drive mechanism, and the dump valve is movable into an open position in response to the skid signal to release fluid from the stop chamber whereafter the pump plunger can engage with the drive mechanism.
37 Citations
21 Claims
- 1. An hydraulic anti-skid system for a vehicle comprising a vehicle brake, a supply of operating fluid for applying said brake, skid sensing means for producing a skid signal to modulate the supply of operating fluid from said supply to said brake, a pump having a piston assembly, a drive mechanism for said pump, and means defining a stop chamber, said piston assembly comprising a pump plunger reciprocable in a bore by means of said drive mechanism, a signal piston, a coupling between said signal piston and said pump plunger, and resilient means for urging said pump plunger out of engagement with said drive mechanism, said signal piston having a first area which is exposed to pressure from said supply or from said brake when said brake is applied to urge said signal piston in a direction such that said pump plunger can engage with said drive mechanism, and a dump valve for controlling fluid in said stop chamber to which said piston assembly is exposed at least after said brake has been applied, said dump valve being normally closed to trap fluid in said stop chamber in order to hold said piston assembly in a retracted position in which said pump plunger is disengaged from said drive mechanism, and said dump valve being movable into an open position in response to said skid signal to release fluid from said drive mechanism.
Specification