Drive device for brake system, brake system

Abstract

The invention relates to a drive device (2) for a brake system (1) of a motor vehicle, the drive device comprising a housing (14), an electric motor (13), the electric motor having a rotatably mounted drive shaft (12), wherein the drive shaft (12) is connectable or connected to an actuator element (4) of a parking brake (1) via a planetary gear mechanism (8) arranged in the housing (14), wherein the drive shaft (12) is rotatably mounted in a bearing cap (15) arranged in the housing (14). Provision is made for the bearing cap (15) to be made of plastic.

Description

Technical Field

[0001] The invention relates to a drive device for a brake system of a motor vehicle, comprising a housing, an electric motor, a drive shaft, wherein the drive shaft is connectable or connected to an actuator element of a parking brake via a planetary gear mechanism arranged in the housing, and wherein the drive shaft is rotatably supported in a bearing cover arranged in the housing.

[0002] Furthermore, the invention relates to a brake system for a motor vehicle, comprising a housing and an actuator element, in which an electric motor is arranged and by which the actuator element can be driven, wherein a planetary gear is interposed between the actuator element and the electric motor. Background Art

[0003] Drive devices of the type described above are known from the prior art. As the electrification of motor vehicles increases, so too does the electrification of braking systems. Parking brakes, in particular, are already electrically driven in series vehicles. For this purpose, drive devices exist that include an electric motor, in particular an electric motor, which drives, for example, a drive spindle of the parking brake to move the brake piston. To achieve high torques or high contact pressures through the brake piston, a planetary gear mechanism is interposed between the electric motor and the brake piston, acting as a speed change mechanism. The drive shaft of the electric motor is, in particular, connected in a rotationally fixed manner to the sun gear of the planetary gear mechanism, and the drive spindle is connected in a rotationally fixed manner to its planetary gear carrier. To support the shaft, the shaft is rotatably supported, for example, by means of rolling element bearings, in a bearing cap disposed in the housing. Summary of the Invention

[0004] The drive device according to the present invention, having the features of claim 1, has the advantage that, due to the advantageous design of the bearing cap, a highly integrated design of the drive device is provided, which robustly ensures all functions within a small installation space. The number of components of the drive device is reduced, thereby reducing assembly and manufacturing time, with corresponding cost advantages. This is achieved according to the present invention by manufacturing the bearing cap from plastic. This has the advantage that, on the one hand, the bearing cap itself is designed to be cost-effective and weight-saving, and that it can be supplemented with additional functions or elements of the drive device with minimal additional effort.

[0005] According to an advantageous embodiment of the present invention, the bearing cap forms the ring gear of the planetary gear train. The ring gear of the planetary gear train is thus directly integrated into the bearing cap, which also supports the drive shaft of the electric motor. By forming the bearing cap from plastic, the ring gear can be integrated into the bearing cap using simple means and at a low cost during manufacturing. The ring gear and the bearing cap are thus formed integrally from plastic.

[0006] According to a preferred development of the invention, the bearing cap has at least one steel ring that is at least partially injection-molded with the plastic material of the bearing cap. The steel ring strengthens and reinforces the bearing cap, resulting in a two-component component that, on the one hand, is characterized by the low weight of the plastic and, on the other hand, at least partially provides the robustness familiar from a steel bearing cap.

[0007] Particularly preferably, the steel ring has an enlarged edge section extending over the entire circumference, which is overmolded with the plastic material of the bearing cap. By overmolding the enlarged edge section, the plastic part of the bearing cap and the steel ring are connected to each other in a form-fitting manner. The plastic material engages the edge section of the steel ring from behind, thereby achieving a particularly strong connection.

[0008] The steel ring preferably has a plastic-free press-in section extending over the entire circumference, with a cylindrical sleeve-shaped circumferential surface for contact with the housing. Since the press-in section is free of plastic, the steel ring, serving as a support for the bearing cap, can advantageously be pressed into a corresponding receptacle in the housing, in particular without damaging the plastic material of the bearing cap. This achieves a functional separation, wherein the retaining force for orienting and retaining the bearing cap in the housing is provided by the steel ring, while the hollow gear is provided solely by the plastic material. According to an alternative embodiment of the present invention, the press-in section is formed by the bearing cap itself and is therefore made of plastic. In this regard, the steel ring is omitted according to this embodiment. According to another embodiment of the present invention, the steel ring is preferably completely surrounded by the plastic of the bearing cap, in particular, is injection-molded around it.

[0009] In particular, the outer diameter of the press-fit section is slightly larger than the inner diameter of the receiving section of the housing for the bearing cap, so as to achieve a press fit between the bearing cap or the steel ring of the bearing cap and the housing. This also ensures simple assembly of the bearing cap in the housing.

[0010] Furthermore, it is preferably provided that the bearing shield has at least one receiving recess and / or at least one receiving projection for arranging a sensor, in particular a rotor position sensor, on the bearing shield. The receiving recess and / or the receiving projection enable an advantageous form-fitting arrangement of the rotor position sensor on the bearing shield, thereby ensuring simple assembly and a robust arrangement of the rotor position sensor on the bearing shield.

[0011] Particularly preferably, the receiving recess and / or receiving projection are designed to receive a circular circuit board of the sensor. This allows the sensor or its circuit board to be arranged and held in the receiving recess and / or on the receiving projection in a particularly form-fitting manner. This eliminates the need for additional fixing or mounting means.

[0012] Particularly preferably, the bearing cover forms a plug connector for connection contacts of the drive device, for example, for electrical contacts of sensors. This allows an electrical connection to the motor to be automatically established when the bearing cover is installed in the drive device. In particular, the plug connector comprises a sleeve protruding axially from the bearing cover. This sleeve is integrally formed with the bearing cover and preferably has an insertion chamfer into which the connection contacts of the motor can be inserted. Advantageously, one or more electrical conductors are guided into the sleeve, which are already injection-molded with the plastic material of the bearing cover during its manufacture.

[0013] According to a preferred refinement of the present invention, a printed circuit board is arranged on a section of the bearing shield, said printed circuit board carrying or comprising the aforementioned rotor position sensor. This results in an advantageously compact arrangement. In particular, the printed circuit board is a component of the rotor position sensor, wherein one or more coils, in particular a receiver coil and a transmitter coil, are preferably arranged on the printed circuit board and are connected in the form of a resolver in order to determine the rotor angular position of the rotor of the electric machine.

[0014] The brake system according to the invention having the features of claim 10 is characterized by the drive device according to the invention. This results in the advantages already mentioned. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Hereinafter, the present invention will be explained in more detail with the aid of the accompanying drawings.

[0016] Figure 1 An advantageous parking brake is shown in a simplified longitudinal section.

[0017] Figure 2 The bearing cap of the parking brake is shown in a simplified sectional view. DETAILED DESCRIPTION

[0018] Figure 1A simplified longitudinal section shows an advantageous braking system 1 for a motor vehicle (not shown in detail here). Braking system 1 comprises a drive device 2, which is operatively connected to an actuator 3 for a parking brake. Actuator 3 comprises, in particular, an actuator element 4, in the present case in the form of a brake piston or hydraulic piston, which can be axially displaced by a spindle drive 5. A drive spindle 6 of spindle drive 5, designed as a hollow spindle, is connected to a planetary gear carrier 7 of a planetary gear train 8. Planetary gears 9, rotatably mounted on planetary gear carrier 7, interact with a sun gear 10 and an annular gear 11 of planetary gear train 8. Sun gear 10 is connected in a rotationally fixed manner to a drive shaft 12 of an electric motor 13 of drive device 2.

[0019] The drive device 2 further comprises a housing 14 in which the electric motor 13 and the planetary gear mechanism 8 are arranged. Furthermore, a bearing shield 15 is arranged in the housing 14 and has a first bearing section 16 in which a rolling element bearing 17 is arranged in the present case and operatively connected to the drive shaft 12. In particular, the inner ring of the rolling element bearing is connected to the drive shaft 12 in a rotationally fixed manner, while the outer ring of the rolling element bearing 17 is held in a rotationally fixed manner on the section 16 of the bearing shield 15.

[0020] In a second section 18 following the first section, the bearing cap 15 forms the ring gear 11 of the planetary gear 8 , the inner diameter of which is greater than the inner diameter of the first section 16 . The ring gear 11 is thus integrated in the bearing cap 15 .

[0021] Figure 2 A perspective sectional view of a bearing cap 15 is shown. The bearing cap 15 is essentially made of plastic, which makes it particularly cost-effective to produce the bearing cap in one piece with the internal gear 11. Between the section 18 and the section 16 of the bearing cap 15, the bearing cap 15 forms a step due to a change in diameter, which is formed as an annular disk section 19. On the side of the section 18 facing away from the section 16, an annular disk section 20 of the bearing cap is also formed, which extends radially outward from the internal gear 11.

[0022] On the outer circumference of the annular disk segment, a steel ring 21 is assigned to the annular disk segment 20. The steel ring has an L-shaped cross section, wherein a leg 22 extends into the annular disk segment 20 and is injection-molded or surrounded by the plastic material of the bearing cover 15. The other leg 23 of the L-shaped steel ring 21 extends axially forward from the annular disk segment 20, more precisely in the direction of the side of the bearing cover 15 facing away from the segments 18 and 16. While the leg 22 is surrounded by the plastic material, the leg 23 of the steel ring 21 is free of plastic and forms a press-in section 25 of the bearing cover 15 on its outer side 24. Here, the outer diameter of the press-in section 25 is slightly larger than the inner diameter of the accommodating section 26 of the housing 14 of the drive device 2, so that the bearing cover and the steel ring 21 can be pressed into the housing 14 and as shown in FIG. Figure 1 It is preferably pressed in as shown in FIG.

[0023] As in Figure 2 As further shown in FIG, segment 19 is preferably also assigned a rotor position sensor 27 having an annular printed circuit board 28, which is inserted into a receiving recess 29 of segment 19, which is coaxial with the annular bearing shield 15, on the side facing away from the internal gear 11 and is thus held in a form-fitting manner on the bearing shield 15. The printed circuit board 28 carries, in particular, a transmitter coil and a receiver coil, which are operated by a computing unit in order to determine or monitor the rotor angular position of the rotor of the electric motor 13 by induction.

[0024] Optionally, the bearing shield 15 also has a connection device 30 via which the rotor position sensor 27 can be electrically contacted. For this purpose, the connection device 30 is designed as a plug connector 31 protruding from the section 20 . Electrical lines 32 are guided from the plug connector 31 through the plastic material of the bearing shield to the section 19 for electrically contacting the sensor 27 . The electrical lines 32 are already surrounded or overmolded with the plastic material, particularly during the manufacture of the bearing shield. The plug connector 31 particularly comprises a sleeve protruding axially from the annular disk section 20 . This sleeve is integrally formed with the bearing shield 15 , and mating or connecting contacts of the electric machine can be introduced into this sleeve, particularly when the bearing shield 15 is installed in the housing 14 , in order to electrically contact the sensor 27 .

[0025] According to another embodiment (not shown here), the steel ring 21 is completely surrounded by the plastic material of the bearing cap 15. It is also conceivable to design the bearing cap 15 without the steel ring 21, so that the press-fit section 25 is made solely of the plastic material of the bearing cap 15. It is also conceivable to arrange the internal gear 11 as a separate element in the bearing cap 15, so that the internal gear can also be made of a different material than the bearing cap 15.

Claims

1. A drive device (2) for a brake system (1) of a motor vehicle, comprising a housing (14), an electric motor (13), the electric motor having a rotatably mounted drive shaft (12), wherein: The drive shaft (12) is connectable or connectable to an actuator element (4) of the brake system (1) via a planetary gear mechanism (8) arranged in the housing (14), wherein the drive shaft (12) is rotatably supported in a bearing cover (15) arranged in the housing (14), characterized in that the bearing cover (15) is made of plastic and has at least one receiving recess (29) and / or at least one receiving projection for arranging a sensor (27) on the bearing cover (15), wherein the receiving recess (29) and / or the receiving projection of the annular circuit board (28) for accommodating the sensor (27) are annular in shape, and the bearing cover (15) has at least one steel ring (21) that is at least partially injection-molded by the plastic material of the bearing cover (15).

2. The driving device according to claim 1, characterized in that The bearing cover (15) forms the hollow wheel (11) of the planetary gear transmission (8).

3. The driving device according to claim 1, characterized in that The steel ring (21) has an enlarged edge section extending over the entire circumference, which is injection-molded with the plastic material of the bearing cap (15).

4. The driving device according to claim 1, characterized in that The steel ring (21) has a press-in section (25) which extends over the entire circumference and is free of plastic material and has a cylindrical sleeve-shaped circumferential surface for contact with the housing (14).

5. The driving device according to claim 4, characterized in that The outer diameter of the press-in section (25) is designed to be slightly larger than the inner diameter of a receiving section (26) of a housing (14) for the bearing cover (15) in order to achieve a press fit.

6. The driving device according to claim 1 or 2, characterized in that: The bearing cover (15) has a plug connector (31) which is formed integrally with the bearing cover (15) and protrudes axially from the bearing cover (15).

7. The driving device according to claim 1 or 2, characterized in that: A circular circuit board (28) having a rotor position sensor (27) is arranged in the receiving recess (29).

8. The driving device according to claim 6, characterized in that The plug connector (31) is designed for electrical contacting of the electric motor (13).

9. A brake system (1) for a motor vehicle, comprising a drive device (2), the drive device having a housing (14), an electric motor (13) being arranged in the housing, the brake system having an actuator element (4) which can be driven by the electric motor (13), wherein: A planetary gear mechanism (8) is connected between the actuator element (4) and the electric motor (13), characterized in that the drive device (2) is configured according to any one of claims 1 to 8.

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