Gm Global Technolgoy Operations, Inc.

Meritor Heavy Vehicle Systems Limited

Meritor Heavy Vehicle Technology, LLC

David L Brademeyer

Christos T Kyrtsos

Roy Lee Hayford

Gerald D Anderson

Neil Williams

Juergen Dreher

Wilfried T Giering

Timothy M Welch

Donald L Parker

Wilfred Giering

A self-servoing disc brake assembly is provided that includes a driven rotor member having a first inner surface with a plurality of first pockets. The driven rotor member also includes a first friction surface spaced from the first inner surface. A movable rotor member is supported on the driven rotor member and is movable relative to the driven rotor member between non-servoed and servoed positions. The rotor members are spaced a first distance in the non-servo position, and the rotor members are spaced a second distance which is greater than a first distance in the servo position. The movable rotor member includes a second inner surface with a plurality of second pockets adjacent to the first inner surface and a friction surface spaced from the second inner surface. A plurality of balls are arranged between the first and second pockets with at least one of the first and second pockets being ramped. A friction member, such as a disc brake pad, is arranged adjacent to the second friction surface and is movable between engaged and non-engaged positions. The friction member is spaced from the second friction surface in the non-engaged position and the friction member is in contact with the second friction surface in the engaged position to rotate the movable rotor member to the servoed position and produce a supplemental brake clamping force. As the brake pads are moved into engagement with the driven and movable rotor members, a shear force is created on the second friction surface. The shear force causes the movable rotor member to rotate relative to and away from the driven rotor member. As a result, for a particular brake input force a larger braking torque is achieved.

Self-servoing disc brake rotor

The braking mechanism comprises a toggle lever, a brake pad, and an incline. An incline actuates the braking mechanism by forcing an extension of the toggle lever. As the toggle lever extends, it pushes the brake pad closer to the surface to be slowed. Multiple toggle levers may be used to distribute the force across the brake pad. This configuration allows a single input from the incline to actuate both toggle levers. By adjusting the width of the incline actuating the toggle lever, the force on the brake pad may be adjusted.

Brake actuation using a toggle clamp

A brake adjuster is provided for a vehicle brake such as for heavy duty vehicle. The brake adjuster includes a brake module that produces an electrical signal for adjusting the vehicle brake. The heavy duty vehicle brake typically includes a pair of pistons each having first and second portions that are movable relative to one another. A friction element or brake pad is arranged proximate to the second portion and is movable from a desired position to a worn position as the brake pads wear during operation of the vehicle. In one embodiment of the present invention, the first and second portions are slip fit within a sleeve assembly. At least one adjustment member is arranged between the first and second portions. The adjustment member is constructed from a material which expands in response to an electrical signal, such as a magnetostrictive or a piezoelectric material. The adjustment member moves the second portion relative to the first portion and repositions the brake pads from the worn position to the desired position. In another embodiment, the first and second portions are threaded to one another and movable rotationally relative to one another to adjust the length of the piston. The first portions of the pistons include a plurality of teeth about the outer face. A gear is arranged between the pistons and coupled the teeth of the first portions together. An electric actuator has a driven member that is coupled with at least a portion of one of the pistons teeth to rotate the first and second portions relative to one another to increase the length of the piston and move the brake pad from the worn position to the desired position.

Brake adjuster

A vehicle braking system includes a device for cooling the components of the brake assembly. The air source that is normally used to activate the brake assembly components is coupled with a plurality of flexible conduits that direct air toward one or more of the brake assembly components. A high velocity air nozzle preferably is provided at the end of each conduit. The air from the compressed air source is maintained in a compressed state through the conduits and decompresses as it exits the discharge nozzles. The decompression of the air through the nozzles results in cooling the air and the nearby brake components at which the air is directed.

Brake assembly with air cooling system

Various buoyant valve arrangements are utilized to prevent quick take-up pressure from entering the master cylinder reservoir chamber until the quick take-up pressure reaches the desired value. A resiliently biased check valve is provided which opens at a predetermined quick take-up pressure to limit the amount of quick take-up pressure generated and then vents excess brake fluid from the quick take-up chamber into the reservoir chamber. The check valve may be resiliently biased by a spring or by elastic tension in an O-ring valve member.

Quick take-up master cylinder valve arrangement

A wheel cylinder assembly has telescoping brake actuating pistons with a brake pressure proportioner in the larger actuating piston to proportion brake actuating pressure.

Wheel cylinder assembly with proportioner

A compensation control and blow-off valve unit in a quick take-up master cylinder. In one embodiment, a stamped valve body forms a valve member within a valve chamber which permits compensation flow from the master cylinder reservoir to the pressurizing chambers. It has an O-ring seal controlling a passage from the valve chamber to the reservoir which opens the passage at a predetermined quick take-up pressure to return fluid to the reservoir. Other embodiments use an umbrella valve or a spring biased ball check valve. The valve housing in some embodiments also retains the reservoir housing in sealed position on the master cylinder housing.

Valve assembly

A dual master cylinder has modular proportioners attached to an outlet from each pressurizing chamber. The master cylinder is shown installed in an X-split vehicle brake system. The master cylinder assembly includes a pressure failure warning device. The arrangement provides a minimum number of leak points, permits the master cylinder and the modular proportioners to be built and tested separately, and enhances serviceability since the modular proportioners can be separately replaced without removing the master cylinder. It also permits the master cylinder to be of a universal type with modular proportioners of various proportioning characteristics used in accordance with the particular vehicle application.

Master cylinder assembly and brake system incorporating same

A master cylinder assembly has a low pressure, high volume displacement quick take-up chamber and a high pressure, low volume displacement pressurizing chamber formed by a stepped bore and a stepped piston. A compensation control and blow-off valve unit has a peripheral lip seal type valve providing compensation flow on brake release but preventing flow from the quick take-up chamber during brake apply. A normally closed check valve can open to provide communication between the quick take-up pressurizing chamber and the fluid reservoir. When the pressurizing cup for the high pressure chamber closes its compensation port, the check valve is subjected to the pressure in the quick take-up pressurizing chamber. Initial fluid flow is obtained from the quick take-up chamber past the pressurizing cup into the high pressure chamber. At a predetermined pressure level, arranged to be sufficient to take up lining clearance and initially apply the vehicle brakes, the pressure in the quick take-up chamber opens the normally closed check valve so that fluid from the quick take-up chamber then flows to the reservoir without further pressure buildup in that chamber. As the master cylinder is released, compensation fluid can flow past the peripheral compensation valve to both chambers. When the master cylinder is returned to the fully released position, the check valve is closed. A fluid flow restrictive orifice is provided in parallel with the normally closed check valve to provide a continuous fluid path controlled leak from the quick take-up chamber to the fluid reservoir.

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Centerville, OH, United States of America

David L Brademeyer