Electric wheel brake actuator with improved end position detection

Abstract

An electric wheel brake actuator for motor vehicles, comprising an electric motor-gearbox assembly including a rotor-trans converter assembly comprising at least one nut-spindle assembly (9) in a gearbox housing (8), wherein the wheel brake actuator serves to enable brake means (6a,b) to perform an actuating movement in the direction of the brake rotor, and comprising an elastomer (22) comprising at least two disc springs (48, 49, 50), wherein the elastomer (22) is clamped between a release end stop (20) of the nut-spindle assembly (9) and the gearbox housing (8) to enable automatic electric motor limit switch-off by monitoring the motor current using an electronic control unit (ECU), characterized in that the elastomer (22) is provided to form a spread force-displacement spring characteristic by means of several spring characteristic segments,in that the elastoelement (22) is modularly composed and is arranged as a stacked disc spring column, which includes at least one single disc spring (50) together with a disc spring pack arranged in a contrary, alternating direction relative to the single disc spring (50), and wherein the disc spring pack comprises at least two disc springs (48, 49) stacked one above the other in the same direction.

Description

[0001] The present invention relates to an electric wheel brake actuator comprising the features of the preamble of claim 1 according to WO 2014 / 195329 A1.

[0002] To interrupt or terminate the actuator's power supply, a so-called end-position detection is performed by monitoring the current. This is a necessity for proper internal vehicle status transfer and a compatibility requirement, particularly in conjunction with robot-assisted, communicatively networked, and / or otherwise digitally controlled value-added functions. Because an automated parking brake function must be secured, the same criteria apply. However, the rotor and drive / gear train of these wheel brake actuators are subject to friction and inertia. Furthermore, the system must operate reliably under the most challenging environmental conditions. Customers often find the unbraked retraction of an actuator into a release end position to be inconvenient.Therefore, early, sufficiently sensitive, cost-effective, and reliable detection of the release position is always a crucial prerequisite for the safe and convenient operation of electric wheel brake actuators. WO 2014 / 195329 A1 discloses a cable-operated drum brake actuator 3 of this type, in which a drive nut 14 is axially fixed and rotatably supported externally on a brake holder 2 by means of a rolling bearing 15. The bearing 15 also provides radially centered and tilt-moment-protected support for the drive nut 14. The spindle assembly 9 engages with the drive nut 14 and is guided in the gearbox housing 8 in a rotationally secure and axially displaceable manner.To enable timely electrical shutdown of the cable actuator 3 by means of an electrical release end stop detection, the spindle assembly 9 is provided with a release end stop 20, which serves to abut a housing-side abutment 21. Furthermore, at least one elastic element 22 is arranged between the abutment 21 and the release end stop 20. The elastic element 22 is designed as a space-saving disc spring arrangement. This enables an electronic control unit, in conjunction with the measurement and monitoring of the current consumption of the motor 7, to perform a cost-effective and timely, electrically initiated current shutdown.

[0003] The known design appears to be in need of further development. The object of the present invention is therefore to enable improved end-position detection with simplified manufacturing, while avoiding the disadvantages of the prior art.

[0004] The object of the invention is solved in a particularly innovative manner for the first time based on the features of the preamble of claim 1 in combination with the features of its characterizing element. The elastomeric element 22 is segmented and composed of several spring characteristic segments to form a spread force-displacement spring characteristic. The modularly composed elastomeric element 22 is arranged as a stacked disc spring column, which includes at least one individual disc spring 50 together with a disc spring assembly arranged in an alternating direction relative to the individual disc spring 50, and wherein the disc spring assembly comprises at least two disc springs 48, 49 stacked in the same direction.The modularly segmented assembly allows for particularly efficient adaptation of the spring characteristic curve to the requirements of the respective actuator application, thus offering, for the first time according to the invention, a significantly simplified mass production variation including nonlinear characteristic curve spreading. Consequently, the respective electronic control unit (ECU) is provided with a particularly robust electrical end-stop detection system within the framework of motor current monitoring. Also noteworthy is the particularly space-saving and practical integration of the elastomer element in the vicinity of the rot-trans converter.For a moderate number of components, the solution also offers the advantages of a common-parts strategy, in that the elastomer is configured as a stacked disc spring column, which includes at least one individual disc spring in conjunction with a disc spring assembly arranged in an alternating direction relative to the individual disc spring, and wherein the disc spring assembly comprises at least two disc springs stacked in the same direction. The disc spring assembly may have two identically designed disc springs with a degressive spring characteristic, and wherein the blocking force of the disc spring assembly is designed to be smaller than the blocking force of the elastomer. Furthermore, a preferred embodiment provides that the individual disc spring has a linear or progressive force-displacement spring characteristic, and wherein the blocking force of the individual disc spring corresponds to the blocking force of the elastomer 22.In other words, the single disc spring, acting as a transmission brake, is specifically dimensioned to engage only after the upstream disc spring assembly has already deformed to its block length. Alternatively, the disc spring assembly can consist of two identical disc springs with linear or progressive force-displacement characteristics. In this configuration, the block force of the disc spring assembly corresponds to the block force of the elastomer. Conversely, the single disc spring can have a degressive or linear force-displacement characteristic with a reduced block force. The force-displacement characteristic can also include a gradient inflection point G as well as various sections with a constant or linear gradient. In special cases, an assembly of three or more disc springs is possible.

[0005] Advantageously, the force-displacement spring characteristic curve of a modularly composed elastomer element, as composed according to the invention, comprises at least a degressively curved spring characteristic curve segment AB and a progressively curved spring characteristic curve segment CD connected thereto. Consequently, a comparatively mild, i.e., gentle, damped approach to the end stop is initially enabled, which provides sufficient opportunity for the termination of the current cut-off, and the inertia-induced, gradually continuing gear train can then be reliably decelerated, at the latest in the progressively curved force-displacement characteristic curve segment, in order to reliably prevent a hard end stop.

[0006] Furthermore, the system's control robustness is specifically increased by including at least one largely horizontally oriented spring characteristic segment BC in the force-displacement spring characteristic of the modularly composed elastomer. In this embodiment, the horizontally oriented spring characteristic segment BC is inserted between the degressively curved spring characteristic segment AB and the progressively curved spring characteristic segment CD.

[0007] To streamline production, it is recommended that all disc springs be manufactured from the same sheet steel material.

[0008] The drawing shows, partly schematically and / or in different scales, a section, view or perspective in accordance with the figure description: Fig. 1 a previously published drum brake module comprising a previously known nut-spindle bearing in a gearbox housing, according to WO 2014 / 1195329 A1, for illustrative purposes only, Fig. 2 an enlarged part of the Fig. 1, and Fig. 3 In principle, a preferred embodiment of an elastoelement constructed according to the invention with a spread force-displacement spring characteristic for improved resolution of end stop detection, in a partially greatly magnified partial section, and Fig. 4 a nonlinear force-displacement spring characteristic of a preferred embodiment of an elastomeric element alternately composed according to the invention.

[0009] A known, electrically actuated drum brake module 1 for arrangement on axle components of a motor vehicle comprises according to Fig. Figure 1 shows a brake holder 2 with brake elements 6a,b mounted on it, which are in conjunction with a brake rotor (not shown). On the opposite side of the brake holder 2, an electrically driven cable actuator 3 is attached, which, via a gearbox 4 and a downstream cable 5, engages one or more of the brake elements 6a, b in such a way that these brake elements 6a, b can perform an actuating movement B towards the brake rotor in order to perform a service and / or parking brake function. A support device 11 may be provided between the brake elements 6a, b.

[0010] The gearbox 4 comprises a gearbox housing 8 that accommodates or at least supports the motor 7. The motor 7 consumes direct current, is mechanically or electronically commutated, and is of an inexpensive, readily available standard type.

[0011] The Fig. Figure 1 only indirectly illustrates that an axis A1 of the motor 7 is arranged at a distance x and parallel to an axis A2 of a spindle assembly 9. The adapter 10 is inserted between the cable actuator 3 and the brake holder 2.

[0012] The drive and transmission train features a multi-stage, in particular two-stage, gear and / or belt and / or worm gear and / or planetary gear (mixed combinations of the aforementioned types are possible and desirable) torque converter of the reduction type. A preferably two-stage gear transmission enables a reduction ratio in the range of approximately 7:1 to 25:1. If the downstream lever transmission in the area of ​​the brake elements 6a,b enables a reduction of approximately 5:1, a reduction ratio of approximately 125:1 is achieved. An additional reduction effect from the Rot-Trans converter is also present, resulting in a total reduction effect across the entire drive train of at least approximately 250:1. This transmission train significantly reduces the cost and performance requirements of the motor 7.

[0013] The cable actuator construction consists of... Fig. As shown in Figure 1, the cable actuator 3 is provided as a separately manageable unit on one side 12 of the brake holder 2. It is possible to integrate the Rot-Trans converter as a spindle assembly 9 into the gearbox housing 8 and to guide it within the gearbox housing 8 in a rotationally secure, smooth-running, and backlash-free manner. A modification of the design involves the Rot-Trans converter being located outside the gearbox housing 8, within the brake rotor, and including a spindle assembly 9 or a pivotable lever that is mounted on the brake holder 2. The mounting is preferably provided by a detachable flange.

[0014] As from Fig. As can be seen in Figure 1, the gearbox housing 8 is constructed in multiple sections. The gearbox housing 8 accommodates a number of gearbox components, primarily for torque conversion (low input torque, high output torque), and can also enable a powerless parking brake function via self-locking. The axes A1 and A2 of the motor and gearbox shafts are arranged parallel to each other, offset by a distance X. At least some of the gearbox components can be made of cost-effective plastic material, at least partially. Preferably, powerless self-locking is provided in the rotary converter (spindle arrangement 9), so that the rest of the gearbox assembly is, in principle, largely relieved of clamping forces.

[0015] According to Fig. 1 The gearbox housing 8 at least partially accommodates a Rot-Trans converter assembly with the spindle arrangement 9 for converting the rotary drive motion into a translational output motion. Consequently, for space-saving integration into the known drum brake arrangements, the converter is inserted cost-effectively and compactly (compacted) into an interface between cable actuator 3 and brake holder 2 and is nevertheless guided within the gearbox housing, so that no modifications to the drum brake mechanism, in particular to the lever mechanism or the brake holder 2, are necessary for conversion to the electromechanical cable actuator.

[0016] For applications with a particularly effective, friction-reduced, electromechanical braking function, several rolling elements are located between a drive nut 14, which is essentially metallic, and a spindle assembly 9, which is also essentially metallic. A parking brake function is enabled in the "de-energized" variants by a separate locking, locking, or blocking device. A particularly advantageous device is known, for example, from DE 19826785 A1, the full disclosure of which, with regard to the principles of this locking device, is incorporated herein.

[0017] The force flow of the brake actuation force is as follows. Starting from the brake fluid 6a, b and the cable 5, the generated tensile force is transmitted via the spindle assembly 9 to the drive nut 14. A metallic spacer bushing can serve for direct, rigid brake force support on a flat contact surface 16. This bushing supports an outer ring of the bearing 15 on the brake holder 2. The spacer bushing is preferably molded as an insert into the gearbox housing 8 made of plastic material. The bearing 15 is advantageously designed as a low-friction rolling bearing (angular contact, thrust, axial, or deep groove ball bearing). The described bearing 15 also allows for radially oriented support of the drive nut 14. In a modification of the design, for particularly precise, tilt-resistant support of the drive nut 14, a drive-side and an additionally an output-side bearing can be provided without departing from the invention.

[0018] The spindle assembly 9 engages with the drive nut 14 and is guided in the gearbox housing 8 in a rotationally secure and axially displaceable manner. For this purpose, the gearbox housing 8 has a prismatic or cylindrical guide 19 with at least one or more adapted cam elements, which contribute to the guiding and rotationally secure function by acting as a positive locking element. To enable convenient electrical disconnection from the cable actuator 3, the spindle assembly 9 is provided with a release end stop 20, which serves to abut a housing-side abutment 21. Furthermore, at least one elastic element 22 is provided between the abutment 21 and the release end stop 20. The elastic element 22 is preferably designed as a disc spring assembly, which enables a stiff spring characteristic with a small footprint.This, in conjunction with the measurement and monitoring of the motor's (7) current draw, enables the control unit to perform an efficient and early automatic electrical shutdown. To ensure consistently reproducible shutdowns, the system requires operating conditions (cable friction) that are as constant as possible.

[0019] The compact cable-operated actuator design includes the spindle assembly 9 being slidably guided within a sleeve 23 of the gearbox housing 8. The sleeve 23 is centered relative to a through-opening 24 of the brake holder 2. Preferably, the sleeve 23 extends through the through-opening 24 such that at least a portion of the spindle assembly 9 can be displaced into the interior of the brake rotor. This also serves to automatically center the cable 5.

[0020] Having said that, the special features of the present invention will below be discussed with reference to a preferred embodiment according to Fig. 3, and wherein the special features of a force-displacement spring characteristic for an exemplary embodiment from Fig. 4 emerges.

[0021] An electric motor-gearbox unit is generally integrated into a peripheral electrical vehicle electrical network architecture, as well as a data ring bus, and has at least one assigned electronic control unit ECU including a secure external data network interface, as well as at least one human-machine interface MMI (e.g. display, hardware switches and / or pedals) for manual parking brake actuator control (actuation; release).

[0022] In comparison with known aggregates such as according to Fig. 1 and Fig. In the invention, the elastoelement 22 represents a completely novel configuration, and in addition, a support 21 as well as an intermediate gearbox housing section inserted between them are dispensed with. According to the invention, a gearbox housing pan 30 and a gearbox housing cover 31 are sufficient.

[0023] The elastic element 22 is clamped laterally next to the drive nut 14, between a flank 32 of the drive nut 14 and the release end stop 20 of the spindle assembly 9. The drive nut 14 is designed as a composite component, with the hub 33 containing the nut thread at its center. Furthermore, the drive nut 14 is in a rotationally fixed connection with an externally toothed gear wheel 34, which meshes rotationally with the actuator drive train. This adjacent arrangement allows for a particularly compact configuration and joint assembly, as the elastic element 22 and the drive nut 14 can be economically recessed together in a common recess 35 in the gearbox housing 30.

[0024] The elastic element 22 may be clamped directly between the spindle-side release end stop 20 and the drive nut 14. However, if direct contact is avoided and the number of components is increased accordingly, the elastic element 22 may also be clamped indirectly between the release end stop 20 and the drive nut 14 via at least one other component. An axial bearing 36 may be integrated into the force flow of this indirect support, which in turn is supported on the flank 32 of the drive nut 14. A particularly space-saving design, resulting in a significantly reduced overall length, is achieved if the axial bearing 36 is recessed in a laterally arranged end-face recess 37 with an integrated bearing seat 38 in the hub 33 of the drive nut 14.On the other hand, the elastic element 22 is indirectly supported on the release end stop 20 of the spindle assembly 9 via a spring plate 39 made of cold-formed sheet steel. Particularly for mutual, assembly-friendly centering, also with regard to the respective adjacent interfaces of peripheral components, it can be advantageous if the spring plate 39 is shaped like a cup with a base 40, a wall 41, and a central through-hole 42 as a passage for the spindle assembly 9, which is mounted in the gearbox housing 8 so as to be axially translationally displaceable and rotationally fixed. A recessed, or at least slightly indented, cold-worked base 40 in conjunction with defined stop cams 47 on an end face 43 of the gearbox housing cover 31 is recommended as a stable support.In this context, a particularly compact design is also advantageous, whereby the spring plate 39 is at least partially recessed in the end-face recess 44 of the gearbox housing cover 31 for space-saving integration, resulting in an integral mounting. Especially when the elastomeric element 22 is composite and may contain elastomeric material, or is layered from several individual parts, such as disc springs 48, 49, 50, it is advantageous if this multi-part arrangement can be handled securely by pre-fixing it to the spring plate 39. The elastomeric element 22 is encapsulated by the spring plate 39, with the wall 41 of the spring plate 39 at least partially encompassing a circumference of the elastomeric element 22 from the radial outside.The spring plate 39 may have a mandrel-like centering projection which, acting as a kind of kink protection, at least partially penetrates the elastomer 22 from the inside. In a further embodiment of the modular or pre-assembly concept, the elastomer 22, and / or axial bearing 36, and / or spring plate 39, optionally together with the drive nut 14, form an assembly component of the spindle arrangement 9 such that these components, together with the threaded spindle, can form an assembly that can be linked together in any desired configuration, and this assembly or component can be inserted into the gearbox housing 30 as a bundled, assembled unit.

[0025] The actuator gearbox housing is essentially prefabricated in two parts from a plastic material. The housing arrangement provides that a dividing plane extends between the gearbox housing base 30 and the gearbox housing cover 31 in the area of ​​the drive nut 14 with elastic element 22, such that the gearbox components, in particular the spindle assembly 9 including cable 5 and drive nut 14, can be easily inserted into the recess 35 of the gearbox housing base 30, and the two gearbox housing parts 30, 31 are hermetically welded together permanently after all components have been inserted.In this context, the gearbox housing components can have a hermetically sealed, labyrinthine, and otherwise robust design by means of a frame-like, end-face annular projection, and the gearbox housing pan 30 has an end-face annular bead projection 45 which can be welded into an opposing end-face annular groove recess 46 of the gearbox housing cover 31. For this purpose, ultrasonic welding processes are particularly suitable, especially when using carbon fiber-reinforced, thermally stabilized, injection-moldable thermoplastic gearbox housing materials for further use in the automotive industry.

[0026] As the Fig. Figure 3 shows that the elastoelement 22 is modularly composed of 3 disc springs 48, 49, 50, and the Fig. Figure 4 illustrates that, according to the invention, a non-linearly spread force-displacement spring characteristic is defined. The force-displacement spring characteristic of the modularly composed elastomer 22 comprises at least one degressively curved spring characteristic segment AB and one progressively curved spring characteristic segment CD. As an additional spreading measure, the force-displacement spring characteristic of the modularly composed elastomer may also include at least one largely horizontally directed spring characteristic segment BC. This horizontally directed spring characteristic segment BC is, according to Fig. 4 inserted between the degressively curved spring characteristic curve section AB and the progressively curved spring characteristic curve section CD.

[0027] The design of the elastomeric element 22 is such that it is a stacked column of disc springs, which includes at least one individual disc spring together with a disc spring assembly arranged in an alternating direction relative to the individual disc spring, and wherein the disc spring assembly comprises at least two disc springs stacked in the same direction. Furthermore, the exemplary disc spring assembly has in Fig. 3. Two identical disc springs with a degressive spring characteristic are used, and the block force of the disc spring assembly is designed to be smaller than the block force of the elastomer 22. In other words, with increasing force, the disc spring assembly first reaches its block length (ceases elastic deformation) before the individual disc spring reaches its block length with a correspondingly increased force.

[0028] In general, the single disc spring has a linear or progressive force-displacement spring characteristic, and the block force of the single disc spring corresponds to the maximum designed block force of the elastomer 22. Consequently, the single disc spring serves as a final stop brake, which can continue to deform elastically even after a significant increase in force, although the disc spring assembly has already reached its maximum working capacity by reaching its block length.

[0029] A correspondingly reversed alignment between the design parameters of the spring assembly and the individual disc spring, combined with sensitive and precise digitally clocked electric motor current sampling by the ECU using shortened interval times of, for example, approximately 5 ms, is conceivable in principle. For this purpose, the disc spring assembly could, for example, have two identically designed disc springs with a linear or progressive force-displacement spring characteristic, while the individual disc spring has a degressive force-displacement spring characteristic. Accordingly, the block force of the disc spring assembly could correspond to the maximum designed block force of the elastomer 22.

[0030] As the preferred embodiment according to Fig.As can be seen in Figure 3, all disc springs of the elastomer have identical outer diameters, with the individual disc spring having a larger inner diameter compared to the disc springs of the spring assembly. The wall thickness of an individual disc spring is essentially the same as the total wall thickness of the disc spring assembly of the elastomer.

[0031] The material for the elastomeric element 22 is preferably spring steel. It is advantageous, both in terms of discounts and logistics, if all disc springs of the elastomeric element 22 are made of identical spring steel sheet material. Reference symbol list: 1 drum brake module 2 brake holders 3 Cable pull actuator 4 gearboxes 5 cable pull 6 braking agents 7 engine 8 Gearbox housings 9 Spindle arrangement 10 adapters 11 Support device 12 Outside 13 Inside 14 Drive nut 15 warehouses 16 contact surfaces 17 Leadership 18 case 19 Leadership 20 Release end stop 21 abutments 22 Elastoelement 23 stubs 24 Through opening 25 Exit opening 26 Sealing element 30 Gearbox housing pan 31 Gearbox housing cover 32 Flank 33 hub 34 Gear wheel 35 In-depth study 36 axial bearings 37 Exclusion 38 bearing seat 39 spring plates 40 floor 41 wall 42 Through hole 43 Front 44 Free savings 45 Ring bulge projection 46 Ring groove recess 47 stop cams 48 Belleville washers 49 Belleville washers 50 Belleville washers A2 Axle α1,α2,αm slope B Direction of action Z axis of rotation G Inflection point axial r radial s1,sg wall thickness Overhang MMI Human-Machine Interface MGU (Motor-Gearbox Unit) ECU Electronic Control Unit M electric motor LAN / WLAN Optional (protected) off-board interface to an external data network

Claims

[1] Electric wheel brake actuator for motor vehicles, comprising an electric motor-gearbox assembly including a rot-trans converter assembly comprising at least one nut-spindle assembly (9) in a gearbox housing (8), wherein the wheel brake actuator serves to enable brake means (6a,b) to perform an actuating movement towards the brake rotor, and comprising an elastomer (22) comprising at least two disc springs (48, 49, 50), wherein the elastomer (22) is clamped between a release end stop (20) of the nut-spindle assembly (9) and the gearbox housing (8) to enable automatic electric motor limit switch-off by monitoring the motor current using an electronic control unit (ECU), characterized by, that the elastoelement (22) is provided to form a spread force-displacement spring characteristic by being segmented from several spring characteristic segments, in that the elastoelement (22) is modularly composed and is in existence as a stacked disc spring column, which includes at least one single disc spring (50) together with a disc spring pack arranged in a contrary, alternating direction relative to the single disc spring (50), and wherein the disc spring pack comprises at least two disc springs (48,49) stacked in the same direction. [2] Electric wheel brake actuator for motor vehicles according to claim 1, characterized by , that the force-displacement spring characteristic A - F has a continuous curve shape whose curvature corresponds to an odd function of at least cubic order, or higher order. [3] Electric wheel brake actuator for motor vehicles according to claim 1 or 2, characterized by, that the force-displacement spring characteristic A - F connects a degressively curved spring characteristic segment BC with a progressively curved spring characteristic segment DE. [4] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-3, characterized by , that the force-displacement spring characteristic A - F includes a linearly directed spring characteristic segment C - D, which is constant. [5] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-4, characterized by , that the constant spring characteristic section C - D is inserted between the degressively curved spring characteristic section B - C and the progressively curved spring characteristic section D - E. [6] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-5, characterized by , that the force-displacement spring characteristic A - F has a linearly directed spring characteristic segment A - B; E - F with constant slope α1, α2. [7] Electric wheel brake actuator for motor vehicles according to claim 6, characterized by , that the slope α1 of the spring characteristic curve section A - B is less than or equal to the slope α2 of the spring characteristic curve section E - F. [8] Electric wheel brake actuator for motor vehicles according to claim 6 or 7, characterized by , that the slope data are executed with α2 being greater than or equal to α1 being greater than or equal to a mean slope αm. [9] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-8, characterized by , that the force-displacement spring characteristic AF, in the largely linear constant spring characteristic section C - D, has an inflection point G in the curvature between the degressively curved spring characteristic section B - C and the progressively curved spring characteristic section DE. [10] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-9, characterized by, that the disc spring assembly has two identically designed disc springs (48,49) with a degressive spring characteristic, and wherein the block force of the disc spring assembly is designed to be smaller than the block force of the elastomer (22). [11] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-10, characterized by , that the single disc spring (50) contributes a linear and / or progressively designed spring characteristic curve segment, and wherein the block force of the single disc spring (50) corresponds to a maximum designed block force of the elastoelement (22). [12] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-11, characterized by, that the disc spring assembly has two identically designed disc springs (48,49) which contribute a linear and / or progressively designed spring characteristic section, and wherein a disc spring (50) contributes a linearly and / or degressively curved spring characteristic section. [13] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-12, characterized by , that the block force of the disc spring assembly corresponds to a maximum designed block force of the elastomer (22). [14] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-13, characterized by , that all disc springs (48,49,50) of the elastomer (22) have identical outer diameters, and wherein the disc spring (50) has an increased inner diameter compared with the other disc springs (48,49) of the disc spring assembly. [15] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-14, characterized by , that a wall thickness s1 of a disc spring (50) corresponds to a total wall thickness sg of a disc spring assembly arranged in the opposite direction, comprising disc springs (48,49) arranged in the same direction. [16] Electric wheel brake actuator for motor vehicles according to one or more of claims 1-15, characterized by , that all disc springs (48,49,50) of the elastomer are made of identical, non-rusting, spring steel sheet material.

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