Brakes – Wheel – Axially movable brake element or housing therefor
Reexamination Certificate
1999-07-30
2001-07-17
Oberleitner, Robert J. (Department: 3613)
Brakes
Wheel
Axially movable brake element or housing therefor
C188S2180XL, C188S2640AA
Reexamination Certificate
active
06260669
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to brake rotors for motor vehicles. More particularly the present invention relates to directing airflow into the vents of a vented brake rotor.
Wheeled vehicles are typically slowed and stopped with a braking system that generates frictional forces. One known braking system is the disc braking system which includes a rotor attached to one or more of the vehicle wheels for rotation therewith. The rotor has an annular peripheral section having a pair of outwardly facing annular friction surfaces also known as the braking surfaces.
The disc brake system also includes a caliper assembly secured to a non-rotating component of the vehicle, such as the vehicle frame. The caliper assembly includes a pair of brake pads, each having a backing plate and brake lining material attached thereto. A pad is disposed adjacent each braking surface such that the brake lining material is adjacent the braking surface. The caliper assembly conventionally includes at least one moveable piston operatively connected to the backing plate of at least one of the brake pads. When the driver brakes the vehicle, hydraulic or pneumatic forces move the piston which clamps the brake lining material of the pads against the braking plates of the rotating rotor. As the pads press against the moving rotor braking surfaces, frictional forces are created which oppose the rotation of the wheels and slow the vehicle.
Disc brake systems generate a significant amount of heat during braking by converting the vehicle's kinetic energy primarily to thermal energy when the brake pads are actuated to engage the braking surfaces. As a result, the rotor temperature rises. An excessive temperature rise is undesirable since it may deform the rotor and degrade braking performance.
To improve the performance and wear of disc brake systems, it is desirable to dissipate the heat generated during braking. Vented rotors dissipate heat using a plurality of air passages known as vents which are formed through the peripheral section. For example, some vented rotors include a peripheral section having a pair of annular braking plates connected together in a mutually parallel, spaced apart relationship. Fins connect the inwardly facing surfaces of the braking plates together forming a plurality of passages or vents between the braking plates. As the rotor turns, air flows through the braking plate vents absorbing heat from the rotor thereby cooling the rotor.
The cooling effectiveness of the rotor vents depends in part on the quantity of air moved through the vents. A higher airflow rate through the vents dissipates more heat from the rotor. Therefore, it is desirable to move as much air as possible through the vents as the rotor turns.
It is known that the shape, spacing and orientation of the fins determines the airflow rate through the vents. Various patterns of long and short curved fins have been used to create curved radial vents having varying widths. For example, Shimazu, et al (U.S. Pat. No. 5,427,212) teaches the use of long and short curved fins disposed adjacent each other in alternating fashion to achieve a high airflow rate.
However, it is desirable to provide a vented brake rotor that moves more air through the vents as the rotor turns to improve the cooling effectiveness of the rotor vents during braking.
SUMMARY OF THE INVENTION
The present invention is an vented disc brake rotor having an airflow director for funneling air into the braking plate vents. The airflow director increases the airflow rate through the vents thereby improving the cooling effectiveness of the rotor.
The vented disc brake rotor includes first and second braking plates extending radially outwards from a central hat section. The braking plates are connected together in a mutually parallel, spaced apart relationship. Braking plate fins connect the inwardly facing surfaces of the braking plates together forming a plurality of radial passages or braking plate vents between the braking plates. Each braking plate vent is defined between adjacent braking plate fins and the inner surfaces of the braking plates. The braking plate vents include inlets at the radially inner ends of the vents having predetermined inlet cross sectional areas, and outlets at the radially outer ends of the vents having predetermined outlet cross sectional areas.
The airflow director includes an annular flange extending generally radially inwards from the radially inner end of the second braking plate. The flange includes an inner surface forming an angle with respect to the inner surface of the first braking plate such that the distance between these inner surfaces increases as the flange extends radially inwards. The angle is preferably between 0 and 90 degrees. A plurality of director fins extend from the inner surface of the flange. The director fins are preferably formed integrally with some of the braking plate fins. The director fins extend radially inwardly from the braking plate fins and connect the inner surface of the flange with the inner surface of the first braking plate Alternatively, the director fins are not formed integrally with the braking plate fins, but are disposed between the inner surfaces of the flange and first braking plate in alignment with some of the braking plate fins. These director fins may be connected to the inner surface of the flange, the inner surface of the first braking plate or both.
A director vent inlet is formed at the radially inner end of the director vent. The cross sectional area of the director vent inlets are larger than the cross sectional area of the braking plate vent inlets. The larger director vent inlets and the angled inner flange surface create a funnel which directs more air into the braking plate vents thereby improving the cooling effectiveness of the rotor.
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Hayes Lemmerz International Inc.
Marshall & Melhorn LLC
Oberleitner Robert J.
Sy Mariano
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