The present invention generally relates to vehicle brake systems and more particularly to an actuating unit for an electromechanically operable disc brake for automotive vehicles.
An electromechanical actuating unit of this general type is disclosed in international patent application WO 99/42739. The actuating element in the prior-art actuating unit is formed of the threaded nut of a screw actuator that is used as a reducing gear and has its threaded spindle driven by an electric motor. The anti-rotation mechanism of the threaded nut is provided by means of axial extensions inserted into semi-circular openings of a bearing plate. The bearing plate forms a bearing both for the threaded nut and the threaded spindle.
It is disadvantageous in the prior-art actuating unit that the mentioned anti-rotation mechanism of the actuating element is inappropriate for a modular design of the actuating unit or, respectively, that the reducing gear employed is untestable. Another shortcoming is the comparatively high cost of the unit, which is primarily due to the costly manufacture of the bearing plate and the threaded nut. Still another shortcoming is the risk that the axial extensions will jam in the bearing plate, in particular in the initial phase of the build-up of the clamping force, with the result of an impaired efficiency.
Therefore, an object of the present invention is to disclose an electromechanical actuating unit of the type mentioned hereinabove with a reducing gear that permits independent testing. Another objective is to eliminate the above-mentioned risk of jamming to the best possible extent and to minimize the axial overall length of the entire actuating unit.
According to the present invention, this object is achieved in that the means for providing the anti-rotation mechanism of the actuating element is arranged in a housing accommodating: the reducing gear.
In a favorable improvement of the subject matter of this invention, the means are cylindrical rolls and grooves designed in the housing or the actuating element, respectively.
In this arrangement, it is especially advantageous that the cylindrical rolls are retained in a slide bearing that radially embraces the actuating element.
In another favorable aspect of the subject matter of the present invention, the means is provided by a profiling of the outside surface of the actuating element as well as a mating inside profiling of a slide bearing that is unrotatably incorporated in the housing and accommodates the actuating element.
Preferably, the slide bearing includes radial projections being received in recesses or grooves, respectively, designed in the housing.
In another embodiment of the subject matter of the present invention, the profiling of the outside surface of the actuating element and the inside profiling of the slide bearing are configured as a polygonal profile.
Further, it is particularly favorable that the reducing gear is designed as a screw actuator and that the actuating element is formed of the threaded nut of the screw actuator.
The electromechanical actuating unit of the invention as illustrated in the drawings is used to actuate a floating-caliper disc brake, with the brake caliper (only partially represented) mounted in a stationary holder 29 so as to be slidable. A pair of friction linings 4 and 5 are mounted in the brake caliper so that they face the left and the right lateral surface of a brake disc 6.
In the following, friction lining 4 shown on the right hand in the drawing is referred to as first friction lining, and the other, opposing, friction lining carrying reference numeral 5 is referred to as second friction lining. While the first friction lining 4, by means of an actuating element 7, is movable into engagement with the brake disc 6 by the actuating unit directly, the second friction lining 5 is pressed against the opposite lateral surface of the brake disc 6 by the effect of a reaction force generated by the brake caliper when the arrangement is actuated.
The actuating unit of the present invention which is fitted to the brake caliper by means of fastening means (not shown) has a modular design and is mainly composed of three independent assemblies or modules, respectively, namely of a driving unit 1, first reducing gear 2 actuating the friction lining 4, and second reducing gear 3 interposed between the driving unit 1 and the first reducing gear 2 in terms of effect.
The driving unit 1 mentioned above is comprised of an electric motor 11 which, in the example shown, is a permanent-magnet-energized, electronically commutated motor whose stator 9 is immovably arranged in a motor casing 12 and whose rotor 10 is provided by an annular carrier 13 that carries a plurality of permanent magnet segments 14. The first reducing gear 2 is interposed between the electric motor 11 and the above-mentioned actuating element 7 in terms of effect and, in the example shown, is configured as a screw actuator 16 to 18 accommodated in a part 19, which may also be of integral design with the above-mentioned brake caliper. In this arrangement, the screw actuator comprises a threaded nut 16 and a threaded spindle 17, with several balls 18 being arranged between the threaded nut 16 and the threaded spindle 17 which circulate upon a rotational movement of the threaded spindle 17 and cause an axial or translatory movement of the threaded nut 16. The threaded nut 16 preferably forms the above-mentioned actuating element 7. Further, it can be taken from the drawing that the threaded spindle 17 driven by the electric motor 11 by way of the second reducing gear 3 has a three-part design and is comprised of a tubular first spindle member 20 which interacts with the threaded nut 16, an annular second spindle member 21, and a third spindle member 22 that interacts with the second reducing gear 3. The first spindle member 20 defines with the threaded nut 16 spiral-shaped screw thread undercuts 23 wherein the balls 18 circulate.
The arrangement is preferably chosen so that the rotor 10 of the electric motor 11 drives the spindle member 17 by the intermediary of the second reducing gear 3, and the threaded nut 16 is supported on the first friction lining 4. The rotor 10 is mounted in two radial bearings 8, 15 being arranged in the motor housing 12 or, respectively, in a bearing plate 25 that is axially supported on the motor housing 12.
In the embodiment of the present invention illustrated in the drawings, the necessary motor torque is reduced by an expedient integration of a planetary gear 30-34 forming the above-mentioned second reducing gear 3. The planetary gear, which is interposed between rotor 10 and threaded spindle 17 in terms of effect, is comprised of a sun wheel 30 which preferably includes an externally toothed area on rotor 10, a plurality of stepped planet wheels, two of which are shown and have been assigned reference numerals 31 and 32, and a ring gear 33. Ring gear 33 is formed of an internally toothed area of a cover 26 that represents the case of the planetary gear.
The third spindle member 22 is favorably connected to a planet cage 36 of the second reducing gear 3 by means of a coupling shaft 40. It is especially advantageous that both ends of the coupling shaft 40 and the areas of the third spindle member 22 and the planet cage 36 receiving these ends are so configured that two universal joints 41, 42 develop.
As may further be seen in
The above-mentioned screw actuator is preferably incorporated in a bowl-shaped gearbox casing 24 in such a fashion that its threaded nut 16 is secured against rotation by appropriate means. The anti-rotation means designated by reference numeral 27, is disposed in the area of the gearbox casing 24 close to the first friction lining 4. An elastic seal or sealing sleeve 28 compressed between the threaded nut 16 and the gearbox casing 24 prevents the ingress of contaminants into the interior of the screw actuator.
The constructive design of the anti-rotation means 27 is apparent from
In the second design of the reducing gear illustrated in
Number | Date | Country | Kind |
---|---|---|---|
100 43 387 | Sep 2000 | DE | national |
101 28 251 | Jun 2001 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCTEP01/10084 | 8/31/2001 | WO | 00 | 3/4/2003 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO0221010 | 3/14/2002 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
4035697 | Arnold, Jr. | Jul 1977 | A |
4137784 | Griffin | Feb 1979 | A |
4865162 | Morris et al. | Sep 1989 | A |
5769189 | Heibel et al. | Jun 1998 | A |
6139460 | Drennen et al. | Oct 2000 | A |
6315086 | Schmitt et al. | Nov 2001 | B1 |
6349801 | Koth et al. | Feb 2002 | B1 |
6561321 | Klode et al. | May 2003 | B1 |
6607059 | Kapaan et al. | Aug 2003 | B1 |
Number | Date | Country |
---|---|---|
3737381 | May 1989 | DE |
19519310 | Nov 1996 | DE |
19825683 | Jul 1999 | DE |
19955080 | May 2001 | DE |
0109918 | May 1984 | EP |
9942739 | Aug 1999 | WO |
0121975 | Mar 2001 | WO |
Number | Date | Country | |
---|---|---|---|
20030178264 A1 | Sep 2003 | US |