Planetary gear transmission systems or components – Electric or magnetic drive or control – With electric or magnetic controlled brake
Reexamination Certificate
2002-04-19
2004-03-02
Bonck, Rodney H. (Department: 3681)
Planetary gear transmission systems or components
Electric or magnetic drive or control
With electric or magnetic controlled brake
C188S072100, C188S072800, C475S282000, C475S311000
Reexamination Certificate
active
06699153
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electrically-actuated braking clutch for a transmission in which a floating caliper and apply hub are actuated by an electric motor to selectively brake rotation of a rotor connected to a planetary gear member.
BACKGROUND OF THE INVENTION
Automatic transmissions often include a braking clutch which selectively engages a planetary gear member with the transmission housing by means of a clutch pack which includes stationary and driven friction plates. The driven and stationary friction plates are alternately arranged, and a piston is reciprocally moved toward and away from the friction plates within a cylindrical portion formed by a clutch drum or a casing. An oil pressure chamber is formed on the back side of the piston, and a return spring is arranged on the front side of the piston. The piston is moved back and forth to apply/release the frictional engagement device by feeding/releasing the oil pressure in the oil pressure chamber via an oil passage.
Accordingly, typical transmission brake assemblies require high pressure hydraulic apply oil, pistons, piston return springs, control valves, and appropriate hydraulic channeling to facilitate transmission speed changes.
It is desirable to provide an improved transmission brake in which manufacturing costs may be reduced and braking efficiency may be enhanced.
SUMMARY OF THE INVENTION
The present invention provides an electric motor-actuated disc brake transmission clutch which includes a floating caliper and apply hub which are actuated by the electric motor to selectively brake rotation of a rotor which is connected to a planetary gear member in a transmission.
More specifically, the invention provides a braking clutch for a transmission which includes a transmission housing and a plurality of planetary gear members. The braking clutch includes a floating caliper movably supported on the transmission housing and an apply hub which is actuated by an electric motor. A rotor is operatively connected to one of the planetary gear members and includes a portion extending between the floating caliper and the apply hub to enable selective braking of rotation of the rotor by frictionally engaging the portion of the rotor between the floating caliper and apply hub, thereby braking rotation of the planetary gear member.
Preferably, the frictional engagement of the rotor between the floating caliper and apply hub is provided by a plurality of friction pads. Also, the portion of the rotor which extends between the floating caliper and the apply hub is a plurality of radially extending plates which extend between a corresponding plurality of friction pad plates which are splined to the transmission housing and extend between the floating caliper and apply hub.
Also preferably, a drive screw assembly is rotatably driven by the electric motor and includes a first threaded portion threadedly engaged with the apply hub, and an oppositely threaded portion threadedly engaged with the floating caliper.
In one embodiment, the electric motor is positioned between the floating caliper and the apply hub for selectively moving the floating caliper and apply hub toward each other to frictionally engage the portion of the rotor which extends between the floating caliper and the apply hub.
A transmission in accordance with the invention may include multiple electric motor-actuated disc brake-type clutches for braking different planetary gear members. Also, a single planetary gear set within a transmission may have multiple electric motor-actuated disc brake-type braking clutches.
The braking clutch of the invention is intended to be used in any planetary or lay-shaft, automatic or manually-operated automotive transmission. The device is used in the shifting and braking of transmission gearing components for normal transmission operation.
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Bonck Rodney H.
General Motors Corporation
Hodges Leslie C.
Le David D.
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