Brakes – Operators – Electric
Patent
1999-05-19
2000-12-12
Schwartz, Chris
Brakes
Operators
Electric
188 721, 188 727, 310 83, F16D 5516, F16D 5508, H02K 516
Patent
active
061585580
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an electromechanically operated disc brake for motor vehicles with a caliper as well as an actuating unit located on the caliper, and with two limitedly displaceable friction linings located in the caliper, each of which acts together with one side of a brake disc respectively, wherein one of the friction linings can be brought into engagement with the brake disc directly by the actuating unit via an actuating element and the other is brought into engagement with the brake disc through the effect of the reaction force generated by the caliper, and wherein the actuating unit exhibits an electric motor arranged coaxially to the actuating element as well as a reducing gear unit arranged between the electric motor and the actuating element, with the rotor of the electric motor being ring-shaped and radially disposed about the reducing gear unit.
This type of electromechanically operated disc brake is known from DE-A-195 11 287.3, for example. The actuating unit of the known disc brake consists of an electric motor, whose rotor drives a threaded nut by means of a roller screw drive element or a sun gear. The rotation of the threaded nut is transmitted to an actuator sleeve or causes its axial displacement, and this in turn causes the friction lining activated by the actuating unit to be brought into engagement with the brake disc. For this purpose, the rotor of the electric motor preferably is radially disposed about the roller screw drive element. Unfavorable features of the known electromechanically operated disc brake, in particular, are the relatively high consumption of electric power as well as considerable heating of the electric motor, which occur especially whenever high clamping forces have to be applied for a long period of time.
Hence, the object of the present invention is to propose an electromechanically operated disc brake of the type described above, which can maintain high clamping forces with very slight electric power after these have been applied. In addition, the heating of the electric motor is to be reduced to a minimum.
SUMMARY OF THE INVENTION
This object is solved by the present invention in that means are provided which prevent reverse rotation of the electric motor's rotor when the current supplied to the electric motor is switched off after the electric motor was activated.
In order to render more concrete the concept of the present invention, it is provided that the above-described means be made up of an electromagnet, whose armature is coupled to the rotor rotationally in such a way that longitudinal displacement is possible. The special feature of this type of actuator is the utilization of small air gaps and the ensuing very high starting power.
An advantageous embodiment of the object of the invention provides that there is a force-transmitting connection between the armature and the threaded nut. The armature, for example, can be coupled to the threaded nut by means of a positive-locking or a non-positive connection. For this purpose, the positive-locking connection preferably consists of radial projecting parts formed integrally with or provided on the armature, with said projecting parts being received in grooves provided in the threaded nut. In contrast, the non-positive connection between the armature and threaded nut is formed by means of flexible sheet metal strips which allow a limited relative displacement of the two parts towards each other in an axial direction. These measures ensure that, in case of a power failure in the brake system, the electric magnet and, consequently, the stop function of the brake always reaches the safe state, so that blocking of the brakes in case of a power failure is excluded.
The electric power supplied to the electric magnet is minimized in another advantageous feature of the invention, which provides for a high-resistance winding of the coil of the electric magnet.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in more detail on the basis of an embodimen
REFERENCES:
patent: 4804073 (1989-02-01), Taig et al.
patent: 4836338 (1989-06-01), Taig
patent: 4850457 (1989-07-01), Taig
patent: 5829557 (1998-11-01), Halasy-Wimmer et al.
Balz Jurgen
Bill Karlheinz
Dusil Vladimir
Continental Teaves AG & Co. OHG
Schwartz Chris
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