Brakes – Elements – Shoes
Patent
1997-07-02
2000-09-19
Oberleitner, Robert J.
Brakes
Elements
Shoes
188250G, 188 716, F16D 6900
Patent
active
061198285
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to improvements in disc brake assemblies and components, particularly discs and friction pad configurations.
Conventional vehicle brakes most commonly comprise a rotor disc with a pair of friction material pads respectively acting on opposed braking surfaces of the rotor disc in a dry environment. Such systems have a number of significant disadvantages in that both the disc and particularly the friction material pads wear during use allowing wear particles to be released into the atmosphere which is polluting and may well be a health risk. Moreover the performance of such brakes is not uniform and varies considerably over time, particularly, as a result of friction pad wear and external factors such as whether water or other liquids get onto the braking surfaces during use.
Forms of wet disc brake are also known where a plurality of friction material discs are provided within a sealed brake housing containing oil. Such wet disc brakes have usually utilised oils of 7-8 or higher centistokes mm.sup.2 /sec at 100.degree. C. viscosity. Such oils normally also had a low viscosity index of 100 which caused substantial viscosity alterations as the oil temperature changed. The discs are provided such that some carrying grooved friction material rotate and other plain discs are stationary and braking effect is achieved by axially forcing the discs together. The oil is provided primarily as a coolant and for this purpose oil circulates through the grooves in the rotating discs. Oil of 7-8 (or higher) centistokes was, however, considered necessary to promote hydrodynamic lubrication and resistance to pressure "squeeze out" in the interengaged friction zone to suppress stick slip, wear, and localised overheating of the brake friction discs and plates. The drawback of utilising hydrodynamic lubrication regime is that a lower friction coefficient results in the interengaged region. Thus, because these oils cause an adverse effect on friction levels, it is necessary to have the much greater braking surface area provided by the plurality of discs. Moreover the configuration of these systems are generally considerably different to those of the dry friction systems described in the preceding paragraph making it difficult to interchange the respective assemblies.
In an earlier filed International Patent Application No. PCT/AU92/00540, there is also disclosed a brake assembly for a vehicle of the type comprising a single rotor disc adapted to rotate with an axle end and a stationary housing enclosing the rotor disc with one or more seals acting to provide a substantially sealed but pressure equalised zone surrounding at least a brake effect region of said rotor disc. At least one pair of friction pads is provided adapted to be engaged against opposed braking faces of a peripheral zone of the rotor disc, and the housing is formed so that it can contain a liquid in at least part of the braking zone. In one part of its disclosure, the aforesaid International Application indicates the liquid may be maintained at a level above the seals so as to prevent ingress of contaminants Into the interior of the housing and particularly in the area of the braking surfaces and friction pads. The aforesaid International Patent Application further discloses friction pads including backing plates with friction material secured thereto, the friction material having rotor disc engaging faces with one or more grooves formed therein of particular configuration. The aforementioned brake arrangement will, however, benefit from a minimum of liquid or lubrication and the grooves are provided for the purpose of oil skimming and draining from the braking surfaces in contrast to other oil immersed brake systems where grooves are provided to assist with oil circulation.
The objective of the present invention is to provide improved friction material products, particularly brake pads and other components, capable of use in brake assemblies of the type shown in the aforesaid International Patent Application.
A further preferred ob
REFERENCES:
patent: 3405786 (1968-10-01), Goode
patent: 3623577 (1971-11-01), Scharlack
patent: 4236612 (1980-12-01), Bayliss
patent: 4501347 (1985-02-01), Cerny et al.
patent: 5564533 (1996-10-01), Parsons
patent: 5816901 (1998-10-01), Sirany
Brake Technologies Pty. Ltd.
Oberleitner Robert J.
Sy Mariano
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