Fluid-pressure and analogous brake systems – With pump
Patent
1981-05-15
1984-03-06
Butler, Douglas C.
Fluid-pressure and analogous brake systems
With pump
188 724, 188181A, 303 93, 303116, 303117, 303119, 303DIG1, 303 68, B60T 804, B60T 1314, F16D 55224, F16D 6516
Patent
active
044350210
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a vehicle brake actuator of the kind which includes pressure-applying means arranged and operable, in use, to urge at least one friction element into braking engagement with a co-operating element fixed to a member to be braked. The invention relates also to a power braking system including one or more brake actuators of the aforesaid kind and in which an electromechanical valve is operable in response to actuation of brake control means, such as a driver-operated pedal, to cause the application of pressure from a pressure accumulator to the or each pressure-applying means in controlled manner.
1. Description of the Prior Art
Conventional power braking systems for vehicles usually incorporate at least two pressure accumulators to provide for effective fail-safe operation, together with a pump for charging the accumulators, a fluid reservoir for containing a supply of operating fluid, a control valve for controlling the supply of said fluid to the pressure-applying means of one or mre brake actuators, and a control unit for actuating the control valve in response to the operation of brake control means to supply actuating pressure from the reservoir to the pressure-applying means. The aforesaid items of equipment are habitually located on the vehicle body, usually in the engine compartment, and consequently require extended and often tortuous runs of fluid conduits to supply the brake actuators at the vehicle wheels, necessitating involved installation procedures.
BRIEF SUMMARY OF THE INVENTION
An object of the invention is to provide a brake actuator of the aforesaid kind, and particularly a disc brake caliper, which enables a compact vehicle power braking system to be produced requiring a minimum of space within the engine compartment and which facilitates the installation of such a system in a vehicle.
According to the invention, a vehicle actuator of the aforesaid kind embodies a pressure accumulator and electrical valve means operable to supply pressure, in use, from the accumulator to the pressue-applying means in response to the actuation of brake control means.
The actuator may also embody a pump for charging the accumulator. The pump and drive means therefor may conveniently be positioned inwardly of the pressure-applying means. In a typical practical arrangement, the pressure-applying means has a piston of hollow cylindrical form and at least the drive means is then preferably housed within the piston, thereby making use of space which is usually wasted in a conventional brake actuator.
Preferably, the actuator also embodies a reservoir for brake fluid and this may be positioned radially outwardly of the pump, conveniently being of annular form and at least partially surrounding the pump. The actuator may also have a control unit for the valve means embodied therein.
One especially advantageous form of the actuator embodies means for detecting an incipient skid condition of the braked wheel and operating in conjunction with the control unit to actuate the valve means in a manner such as to correct the skid, usually by causing a reduction in the braking force applied to the wheel until the skid condition has been corrected. When the actuator is in the form of a disc brake caliper, the skid detecting means may conveniently be an inductive or other similar sensor carried by the caliper body and co-operating with a toothed metal formation carried by a brake disc to produce a signal representative of the angular speed of the disc, and thus of a wheel being braked, said signal being fed to the control unit.
DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a diagrammatic representation of a power braking system suitable for use in a vehicle, and
FIG. 2 is a side elevational view, partly in longitudinal cross-section, of one embodiment of the vehicle brake actuator of the invention in the form of a disc brake caliper.
FIG.
REFERENCES:
patent: 3507542 (1970-04-01), Cannella
patent: 3520575 (1970-07-01), Steigerwald
patent: 3724914 (1973-04-01), Skoyles
patent: 4003013 (1977-01-01), Seilly
patent: 4131325 (1978-12-01), Bayliss
"Helenoid Actuators: A New Concept in Extremely Fast Acting Solenoids", by A. H. Seilly, SAE Technical Paper Series, 790119, Society of Automotive Engineers, Inc., Warrendale, PA, 1979.
Butler Douglas C.
Lucas Industries Limited
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