Brakes – Elements – Cooling and lubricating
Reexamination Certificate
1999-10-27
2001-10-02
Oberleitner, Robert J. (Department: 3613)
Brakes
Elements
Cooling and lubricating
Reexamination Certificate
active
06296087
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to a wet disc brake cooling system and more particularly to a wet disc brake cooling system that is powered by the vehicle's axle shaft.
Heat builds up in wet disc brake systems due to the numerous frictional forces within the brake system. As heat builds up within the brake housing, the temperature of the brake fluid within the brake housing increases. The high temperature of the brake environment also increases the temperature of other vehicle components, namely the axle housing. There are several known systems used to reduce the temperature of the brake fluid, thus reducing the heat build up within the wet disc brake system.
One system involves forced cooling of the wet disc brake. Forced cooling requires cooling lines and an external pump that pumps brake fluid out of the brake housing, through the cooling lines and back into the brake housing. This system is strictly limited to drawing the brake fluid from the brake housing, cooling the fluid, and directing the fluid back to the brake housing. There are several disadvantages of this system. First, it is expensive because a separate part, the external pump, needs to be included in the system. Second, the additional part increases the overall weight of the vehicle. Third, the system only cools the brake environment. This system does not actively cool the axle housing environment.
Another system is a sump cooling system through the axle. In this type of system the fluid flows freely between the brake housing and the axle housing. The sump cooling system does not require any forced cooling lines. Rather, the brake fluid flows from an environment with an increased temperature, the brake housing, to a cooler environment, the axle housing. The disadvantage of the sump cooling system is that a high thermal cooling gradient develops between the brake and axle.
SUMMARY OF THE INVENTION
In general terms, a disclosed wet disc brake cooling system overcomes the above problems with other types of wet disc brake cooling systems by increasing the transfer of thermal energy from the axle and brake housings into the surrounding ambient air without an external cooling system. The disclosed invention has the advantage of the sump cooling system, in that the fluid freely flows between the brake housing and the axle housing without the attendant disadvantages. The wet disc brake fluid cooling system cools the fluid by drawing the brake fluid either out of the brake housing or the axle housing. The system includes an internal pump for drawing the brake fluid into an external cooling tube for reducing the temperature of the fluid and guiding the fluid back to either the axle housing or the brake housing, depending upon the flow of the fluid. The internal pump is driven by the vehicle's axle shaft.
These and other features of the invention may be best understood from the following specification and drawings. The following is a brief description of the drawings.
REFERENCES:
patent: 3118387 (1964-01-01), Aldrich
patent: 3590960 (1971-07-01), Reynolds
patent: 3592304 (1971-07-01), Thompson
patent: 3730301 (1973-05-01), Heck et al.
patent: 3814222 (1974-06-01), Koivunen
patent: 3907073 (1975-09-01), Harrison
patent: 4069906 (1978-01-01), Handke
patent: 4508200 (1985-04-01), Cigognini
patent: 4736821 (1988-04-01), Ries
patent: 5190123 (1993-03-01), Hvolka
Bissonnette Lee A.
Groves Barry S.
Carlson & Gaskey & Olds
Kramer Devon
Meritor Heavy Vehicle Systems LLC
Oberleitner Robert J.
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