192 clutches and power-stop control – Transmission and brake – Motor vehicle
Reexamination Certificate
2000-06-09
2002-02-12
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Transmission and brake
Motor vehicle
C188S071600, C188S26400E, C475S160000
Reexamination Certificate
active
06345712
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to an axle assembly and is more particularly directed to a liquid cooled brake in an axle assembly.
2. Summary of the Prior Art
In a differential axle assembly the differential is provided with a pair of side journals which are rotatably supported by a pair of spaced bearing and bearing caps carried on the transaxle differential housing. A pair of axle shafts extend outwardly from the differential unit through the bearings and bearing caps. In heavy duty differential assemblies a brake may be provided to brake at least one of the axle shafts. In some arrangements at least one friction disc is splined to each axle shaft. A brake assembly selectively compresses reaction plates which are splined to the axle tube. Compression of the reaction plates causes the reaction plates to frictionally engage the friction discs and consequently apply braking torque thereto. Activation of the brake generates substantial thermal energy which is absorbed by adjacent components which may shorten the useful life of the friction discs and can cause premature failure.
It is an object of the present invention to provide a differential axle assembly with a brake arrangement disposed within the housing that overcomes the drawbacks of the prior art and provides enhanced cooling of lubricating oil flowing there through.
SUMMARY OF THE INVENTION
A differential axle assembly for providing differential torque transfer between an input shaft and two output shafts is disposed within a housing. A plurality of spaced apart friction discs are splined to each of the output shafts. A plurality of reaction discs are splined to a stationery brake housing or trumpet casting in turn fixed relative to the differential housing. A piston or actuator selectively compresses the reaction plates to frictionally engage with the friction plates and apply a braking torque to the output shafts. Grooves are formed in the friction discs to cause lubricating oil to be thrown outward through the friction plates and enter oil channels formed to divert the lubricating oil. The lubricating oil is preferably split off through two oil channels. A first oil channel is formed between the trumpet casting and housing and extends along the differential housing outward toward the wheel end to the exterior of the trumpet casting. A second oil channel extends inward toward the differential case. The lubricating oil absorbs heat as it flows through the brake. This heat is dissipated to the differential housing as it flows through the oil channels. The cooled lubricating oil is then returned to the inner area of the friction discs and the flow process is continuously repeated with rotation of the friction discs. A cored channel is formed on the piston bore to provide a washing action to prevent contaminants from settling into a sealed interface between the piston and piston bore.
REFERENCES:
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patent: 2348499 (1944-05-01), Sawtelle
patent: 2571432 (1951-10-01), Farkas
patent: 4113067 (1978-09-01), Coons et al.
patent: 4468981 (1984-09-01), Ries
patent: 4773512 (1988-09-01), Murakami
patent: 5197574 (1993-03-01), Al-Deen et al.
patent: 5407036 (1995-04-01), Hummel et al.
patent: 5515952 (1996-05-01), Jackson
patent: 55-107132 (1980-08-01), None
Dalton Tony
Dewald Greg
Dana Corporation
Liniak Berenato Longacre & White
Lorence Richard M.
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