Actuation device for a brake system
Patent Information
- Application Number
- EP2023727976
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-05-30
- Filing Date
- 2023-05-17
- Publication Date
- 2025-04-09
AI Technical Summary
Existing actuating devices for braking systems, particularly in electrified vehicles, face challenges in efficiently and cost-effectively forming a rotation-proof connection between the threaded spindle and the rotation locking element, often requiring material connections like welding, which increases assembly complexity and costs.
A positive connection is formed between the rotation locking element and the threaded spindle using radially projecting driver elements or driver toothing, allowing for a mechanically robust and cost-effective assembly without the need for material connections like welding, with options including plastic or metal materials and manufacturing processes like injection molding or cold forming.
This solution reduces manufacturing and assembly costs by simplifying the assembly process, enabling a robust and secure anti-rotation connection that uniformly distributes torque, while also allowing for complex geometries and reduced material usage.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] title
[0003] Actuating device for a braking system
[0004] The invention relates to an actuating device for a braking system, comprising an electric machine, wherein a rotor of the electric machine is arranged in a rotationally fixed manner on a rotatably mounted drive shaft, having a displaceably mounted pressure element, and having a gear device by means of which the drive shaft is operatively connected to the pressure element, wherein the gear device has a displaceable threaded spindle, wherein an anti-rotation element is connected in a rotationally fixed manner to the threaded spindle, and wherein the anti-rotation element cooperates with a housing of the actuating device and / or with an element of the actuating device arranged fixedly to the housing to form an anti-rotation device for the threaded spindle.
[0005] The invention also relates to a braking system.
[0006] State of the art
[0007] A hydraulic braking system of a motor vehicle typically has several friction brake devices. The friction brake devices are operatively connected to an actuating device of the braking system in such a way that the friction brake devices can be actuated by the actuating device. With the increasing electrification of motor vehicles, actuating devices of braking systems are also becoming increasingly electrified. In this regard, it is known to equip an actuating device for a braking system with an electric motor, wherein a rotor of the electric motor is arranged in a rotationally fixed manner on a rotatably mounted drive shaft. To enable actuation of the friction brake devices by the actuating device, the actuating device also has a displaceably mounted pressure element. The drive shaft is operatively connected to the pressure element by a gear device.The gear mechanism is thus designed to convert rotation of the drive shaft into translational movement of the pressure element. For this purpose, the gear mechanism often has a movable threaded spindle. To prevent rotation of the threaded spindle during operation of the actuating device, an anti-rotation element is usually connected to the threaded spindle in a rotationally fixed manner. To prevent rotation of the threaded spindle, the anti-rotation element interacts with a housing of the actuating device and / or with an element of the actuating device that is fixed to the housing. In previously known actuating devices, the anti-rotation element is typically welded to the threaded spindle, so that the rotationally fixed connection between the anti-rotation element and the threaded spindle is formed by a material bond.
[0008] Disclosure of the invention
[0009] The actuating device according to the invention with the features of claim 1 has the advantage that the actuating device can be implemented cost-effectively. According to the invention, the rotationally fixed connection of the anti-rotation element to the threaded spindle is formed by a positive connection. The positive connection is easier to form during assembly of the actuating device than the previously mentioned material connection, so that the assembly effort is reduced. This can reduce the manufacturing costs for the actuating device. Furthermore, the assembly of the actuating device is also facilitated by the fact that it is not necessary for the threaded spindle and the anti-rotation element to be spatially accessible for a welding device. In particular, the rotationally fixed connection of the anti-rotation element to the threaded spindle is formed simply by plugging the two elements together.Preferably, the anti-rotation element is arranged on the threaded spindle in a rotationally fixed manner. According to a preferred embodiment, the transmission device comprises a spindle gear, wherein the spindle gear comprises the threaded spindle. According to an alternative embodiment, the transmission device preferably comprises a ball screw drive, wherein the ball screw drive comprises the threaded spindle. Preferably, the threaded spindle is coupled to the pressure element in such a way that the pressure element can be displaced by the threaded spindle. Alternatively, the threaded spindle preferably forms the pressure element.
[0010] According to a preferred embodiment, the positive connection is formed by at least one radially protruding driver element. Such a driver element allows for a mechanically robust positive connection. The driver element protrudes, for example, radially inward or radially outward. Preferably, the threaded spindle and the anti-rotation element each have at least one radially protruding driver element, with the driver elements interacting to form the anti-rotation device.
[0011] According to a preferred embodiment, a driver toothing of the anti-rotation element meshes with a driver toothing of the threaded spindle to form the positive connection. A driver toothing comprises a plurality of tooth-shaped driver elements arranged one behind the other in the circumferential direction. The driver toothing allows for a particularly robust mechanical positive connection to be realized. In particular, this ensures that, during operation of the actuating device, torques transmitted from the threaded spindle to the anti-rotation element act on the anti-rotation element in a uniformly distributed manner in the circumferential direction of the anti-rotation element.
[0012] According to a preferred embodiment, the anti-rotation element is made of plastic. By manufacturing the anti-rotation element from plastic, even complex geometries, such as the driver element or the driver toothing, can be easily manufactured. In particular, the anti-rotation element is manufactured from plastic using an injection molding process. Particularly preferably, the anti-rotation element is made of glass-fiber-reinforced plastic. This material is highly rigid, allowing the anti-rotation element to be designed comparatively small or slim. This saves material costs and installation space.
[0013] The anti-rotation element is preferably made of a metal material. A metal material also has high strength, so the anti-rotation element can be made comparatively small, thereby saving material costs and space. The anti-rotation element is particularly preferably made of steel. The anti-rotation element is preferably made of a metal material using a cold forming process, for example, by cold forging.
[0014] According to a preferred embodiment, the anti-rotation element is designed as a skeletonized structure with recesses. Particularly when the anti-rotation element is manufactured from glass-fiber-reinforced plastic or a metal material, a solid construction of the anti-rotation element is not necessary to ensure sufficient mechanical strength. The provision of the recesses can therefore further reduce material costs.
[0015] Preferably, the threaded spindle is manufactured using a cold forming process. A cold forming process allows the necessary structural elements of the threaded spindle, such as a screw thread of the threaded spindle or the driver element or the driver toothing, to be manufactured without subsequent machining steps. This reduces the manufacturing costs of the threaded spindle. Alternatively, the threaded spindle can be only partially manufactured using a cold forming process. For example, a blank for the threaded spindle is first produced using a cold forming process. The screw thread and / or the driver element or the driver toothing are then formed using a machining process such as shaping or rolling.According to a preferred embodiment, the anti-rotation element is axially fixed to the threaded spindle relative to the displacement axis of the threaded spindle. This makes the attachment of the anti-rotation element to the threaded spindle particularly robust mechanically, and the threaded spindle, together with the anti-rotation element, can be easily handled as a subassembly, for example, during assembly of the actuating device. According to an alternative embodiment, it is preferably provided that the anti-rotation element has axial play relative to the threaded spindle.
[0016] According to a preferred embodiment, the threaded spindle or the anti-rotation element has an undercut or undercut into which the anti-rotation element or the threaded spindle engages for an axially fixed connection of the anti-rotation element to the threaded spindle. The radial engagement of the anti-rotation element or the threaded spindle in the undercut or undercut, in particular, creates a mechanically robust, axially fixed connection of the anti-rotation element to the threaded spindle. The undercut or undercut preferably extends circumferentially completely through the threaded spindle or through the anti-rotation element. Such an undercut or undercut is technically easy to implement.
[0017] According to a preferred embodiment, the anti-rotation element is axially fixedly connected to the threaded spindle by caulking the anti-rotation element and / or by caulking the threaded spindle. The anti-rotation element and / or the threaded spindle are thus formed by caulking to form an axially fixed connection between the anti-rotation element and the threaded spindle. This allows a mechanically particularly robust non-positive and / or positive connection to be realized. The anti-rotation element is preferably formed by caulking in such a way that it engages, in particular radially, in the undercut or undercut of the threaded spindle. Alternatively or additionally, the threaded spindle is preferably formed by caulking in such a way that it engages, in particular radially, in the undercut or undercut of the anti-rotation element.
[0018] According to a preferred embodiment, the threaded spindle has a first end portion facing the pressure element, and the anti-rotation element is arranged at the first end portion. The first end portion is easily accessible for arranging the anti-rotation element, so that arrangement at the first end portion is preferred. Arranging the anti-rotation element at the first end portion also results in the advantage that the position of the first end portion is defined particularly precisely in the radial direction, which is advantageous for the reliable transmission of axial forces from the threaded spindle to the pressure element.
[0019] According to a preferred embodiment, the anti-rotation element has an annular section, and the threaded spindle is inserted into an opening in the annular section. This advantageously allows the positive connection between the anti-rotation element and the threaded spindle to be realized. For this purpose, an inner surface of the anti-rotation element forming the opening preferably has the driver toothing of the anti-rotation element. Preferably, an outer surface of the threaded spindle radially opposite the inner surface of the anti-rotation element has the driver toothing of the threaded spindle. Preferably, at least one of the aforementioned recesses is formed in the annular section. Particularly preferably, the annular section has at least one annular recess and / or at least one recess in the shape of a ring section.
[0020] The anti-rotation element preferably has at least one radial projection which engages radially in a radial recess of the housing of the actuating device to form the anti-rotation device. The anti-rotation element therefore cooperates with the housing of the actuating device to form the anti-rotation device. This creates a particularly secure anti-rotation device. The anti-rotation element preferably has a plurality of radial projections which radially engage a different radial recess of the housing to form the anti-rotation device. The anti-rotation element particularly preferably has two radial projections which are arranged offset by 180° in the circumferential direction of the anti-rotation element. Preferably, at least one of the aforementioned recesses is formed in the radial projection. The radial projection particularly preferably has one or more prism-shaped recesses.
[0021] Preferably, a sliding shoe is arranged on the radial projection. The sliding shoe ensures low-friction guidance of the radial projection in the radial recess.
[0022] The housing is preferably a cylindrical extrusion. Extrusions are typically inexpensive to manufacture, so that the manufacturing costs for the actuating device are further reduced by designing the housing as an extrusion. A cylindrical element has a circumferentially closed shell wall, wherein the shell wall forms or encloses an axial opening in the cylindrical element. Accordingly, the cylindrical extrusion also has such a shell wall and such an axial opening, wherein the axial opening forms a housing interior of the extrusion. However, the term "cylindrical" does not imply a cross-section with a specific shape. Rather, the cross-section of the extrusion can have different shapes.Preferably, however, the axial opening has an at least substantially circular cross-section. The extruded profile is preferably made of aluminum. Constructing the housing as an extruded profile also offers the advantage that the aforementioned radial recess, into which the radial projection of the anti-rotation element radially engages, can be realized without additional machining steps.
[0023] The invention is explained in more detail below with reference to the drawings. Figure 1 shows a sectional view of an actuating device for a braking system,
[0024] Figure 2 shows a further sectional view of the actuating device,
[0025] Figure 3 is a sectional view of a gear mechanism of the actuating device and
[0026] Figure 4 is a plan view of an anti-rotation element of the actuating device.
[0027] Figure 1 shows a longitudinal section through an actuating device 1 for a braking system 2 of a motor vehicle (not shown in detail). The actuating device 1 has a displaceably mounted pressure element 3, which in this case is designed as a push rod 3. The pressure element 3 is displaceable along a displacement axis 4 in a first direction 5 and in a second direction 6 opposite the first direction 5. The displacement axis 4 corresponds to the longitudinal center axis of the pressure element 3.
[0028] The pressure element 3 is at least partially arranged in a housing 7 of the actuating device 1. In the present case, the housing 7 is a cylindrical extrusion profile 7. In this respect, the housing 7 has a circumferentially closed casing wall 8. The casing wall 8 forms or encloses an axial opening 9 in the housing 7, wherein the axial opening 9 forms a housing interior 10 of the housing 7. In the present case, the axial opening 9 has a circular cross-section. The pressure element 3 is arranged in the housing 7 or the housing interior 10 in such a way that the displacement axis 4 is oriented perpendicular to a cross-sectional area of the housing 7.
[0029] A master brake cylinder 11 of the actuating device 1 is fixedly arranged on the housing 7. In the present case, the master brake cylinder 11 is arranged on a first end face 12 of the casing wall 8. A first hydraulic piston 13 and a second hydraulic piston 14 are displaceably mounted in the master brake cylinder 11, namely in the first direction 5 and in the second direction 6. The master brake cylinder 11 has a plurality of hydraulic connections 15, 16. If the actuating device 1 is installed as intended in the braking system 2, the hydraulic connections 15, 16 are fluidly connected to slave cylinders of friction brake devices of the braking system 2. The friction brake devices can then be actuated by displacing the hydraulic pistons 13 and 14 in the first direction 5. The pressure element 3 is coupled to the hydraulic pistons 13 and 14 in such a way that the hydraulic pistons 13 and 14 can be displaced in the first direction 5 by the pressure element 3.The friction brake devices can therefore be actuated by moving the pressure element 3.
[0030] A housing plate 17 is also fixedly mounted on the housing 7. In this case, the housing plate 17 is arranged on a second end face 18 of the casing wall 8, facing away from the first end face 12. The housing plate 17 at least partially closes the axial opening 9.
[0031] The actuating device 1 also has a drive unit 19. The design of the drive unit 19 is explained in more detail below with reference to Figure 2. Figure 2 shows a cross-section through the actuating device 1. The drive unit 19 has a motor housing 20 in which an electric machine 21 is arranged. An annular rotor 22 of the electric machine 21 is arranged in a rotationally fixed manner on a drive shaft 23, wherein the drive shaft 23 is mounted rotatably about a rotation axis 24. An annular stator 25 of the electric machine 21 is arranged fixedly on the motor housing 20 and radially encloses the rotor 22 with respect to the rotation axis 24. The motor housing 20 is fastened to the housing 7.
[0032] The drive shaft 23 is coupled to the pressure element 3 by a gear device 26 such that the pressure element 3 can be moved by the electric machine 21. Figure 3 shows a sectional view of the gear device 26. The gear device 26 has a threaded spindle 27 which can be moved in the first direction 5 and in the second direction 6. The threaded spindle 27 is coupled to the pressure element 3 such that the pressure element 3 can be moved at least in the first direction 5 by the threaded spindle 27. The threaded spindle 27 has a screw thread 28. The screw thread 28 forms a drive toothing of the threaded spindle 27. The threaded spindle 27 is part of a gear 29 of the gear device 26, which is designed to convert a rotation into a translational movement of the threaded spindle 27. In this case, the gear 29 is designed as a spindle gear 29.In addition to the threaded spindle 27, the spindle gear 29 has a rotatably mounted spindle nut 30. The spindle nut 30 and the threaded spindle 27 are arranged coaxially with each other. An output gear 60 of the spindle nut 30 meshes with the screw thread 28 of the threaded spindle 27 such that the threaded spindle 28 can be displaced by rotating the spindle nut 30. According to a further embodiment, the gear 29 is not designed as a spindle gear, but as a ball screw drive.
[0033] According to the exemplary embodiment illustrated in the figures, the gear mechanism 26 also comprises a worm gear 31 with a worm shaft 32 and a worm gear 33. The worm shaft 32 is formed by the drive shaft 23. The worm gear 33 is arranged in a rotationally fixed manner on the spindle nut 30. According to a further exemplary embodiment, the spindle nut 30 and the worm gear 33 are formed integrally with one another.
[0034] An anti-rotation element 35 is arranged on a first end section 34 of the threaded spindle 27 facing or associated with the pressure element 3. Figure 4 shows a plan view of the anti-rotation element 34, with the viewing direction corresponding to the second direction 6. The anti-rotation element 35 is connected to the threaded spindle 27 in a rotationally fixed manner. The rotationally fixed connection of the anti-rotation element 35 to the threaded spindle 27 is formed by a positive connection 36.
[0035] According to the exemplary embodiment illustrated in the figures, the anti-rotation element 35 has an annular section 61 with an opening 37. The threaded spindle 27 is inserted into the opening 37. An inner surface 38 of the anti-rotation element 35, which forms or surrounds the opening 37, has a first driving toothing 39 with a plurality of tooth-shaped first driving elements 40. The first driving elements 40 protrude radially inward from the inner surface 38. An outer surface 41 of the threaded spindle 27, radially opposite the inner surface 38, has a second driving toothing 42 with a plurality of tooth-shaped second driving elements 43. The second driving elements 43 protrude radially outward from the outer surface 41. The first driving toothing 39 meshes with the second driving toothing 42 to form the positive connection 36.
[0036] The anti-rotation element 35 cooperates with the housing 7 to form an anti-rotation device 44 for the threaded spindle 27. According to a further exemplary embodiment, the anti-rotation element 35 does not cooperate with the housing 7, but rather with an element fixed to the housing. In the present case, the anti-rotation element 35 has two radial projections 45 which protrude radially outward from the annular section 61. However, a different number of radial projections 45 can also be present. In the present case, the radial projections 45 are arranged offset by 180° in the circumferential direction of the anti-rotation element 35. The radial projections 45 engage radially in a respective different radial recess 46 of the housing 7 to form the anti-rotation device 44. In the present case, a sliding shoe 48 is arranged at each of the radially outer ends 47 of the radial projections 45.The sliding shoes 48 ensure low-friction guidance of the radial projections 45 in the radial recesses 46.
[0037] In the present case, the anti-rotation element 35 is made of a glass-fiber-reinforced plastic, for example, by an injection molding process. This material is so strong that a solid construction of the anti-rotation element 35 is unnecessary. In order to reduce material costs, the anti-rotation element 35 is provided with recesses 49 such that the anti-rotation element 35 has a skeletonized design. In the present case, the annular section 61 has two annular section-shaped recesses 49a. The radial projections 45 each have a plurality of prism-shaped recesses 49b. According to a further exemplary embodiment, the anti-rotation element 35 is preferably made of a metal 11 material, for example, by a cold forming process. Even when manufactured from the metal material, the anti-rotation element 35 preferably has the recesses 49.The threaded spindle 27 including the screw thread 28 and the second driving toothing 42 is preferably manufactured by a cold forming process.
[0038] The anti-rotation element 35 is also axially fixed to the threaded spindle 27. In the present case, the threaded spindle 27 has an undercut 50 for this purpose. The undercut 50 extends in the circumferential direction of the threaded spindle 27 completely along the threaded spindle 27. The anti-rotation element 35 is formed by caulking such that the anti-rotation element 35 engages radially in the undercut 50. Alternatively, the anti-rotation element 35 is preferably axially fixed to the threaded spindle 27 by a locking connection. For example, the anti-rotation element 35 has at least one locking projection that engages radially in the undercut 50. According to a further exemplary embodiment, the anti-rotation element 35 has the undercut 50 and the threaded spindle 27 engages radially in the undercut 50 for an axially fixed connection of the anti-rotation element 35 to the threaded spindle 27.
[0039] The actuating device 1 also has an actuating element 51, which is displaceably mounted in an axial opening 52 of the threaded spindle 27. A first end 53 of the actuating element 51 is coupled or can be coupled to a brake pedal of the braking system 2 by an input rod 54, so that the actuating element 51 can then be displaced by actuating the brake pedal. A second end 55 of the actuating element 51 is coupled to the pressure element 3 such that the pressure element 3 can be displaced by the actuating element 51. The friction brake devices can therefore also be actuated by actuating the brake pedal.
Claims
Claims 1. Actuating device for a brake system, comprising an electric machine (21), wherein a rotor (22) of the electric machine (21) is arranged non-rotatably on a rotatably mounted drive shaft (23), comprising a slidably mounted pressure element (3), and comprising a gear unit (26) by which the drive shaft (23) is operatively connected to the pressure element (3), wherein the gear unit (26) has a slidably mounted threaded spindle (27), wherein a rotation-locking element (35) is non-rotatably connected to the threaded spindle (27), and wherein the rotation-locking element (27) cooperates with a housing (7) of the actuating device (1) and / or with a housing-fixed element of the actuating device (1) to form an anti-rotation device (44) for the threaded spindle (27), characterized in that the rotation-locking connection of the rotation-locking element (35) with the threaded spindle (27) is formed by a positive locking connection (36). is.
2. Actuating device according to claim 1, characterized in that the positive locking connection (36) is formed by at least one radially projecting drive element (40,43).
3. Actuating device according to one of the preceding claims, characterized in that a drive toothing (39) of the rotation locking element (35) meshes with a drive toothing (42) of the threaded spindle (27) to form the positive locking connection (36).
4. Actuating device according to one of the preceding claims, characterized in that the rotation locking element (35) is made of plastic, in particular of glass fiber reinforced plastic.
5. Actuating device according to one of claims 1 to 3, characterized in that the rotation locking element (35) is made of a metallic material, in particular by a cold forming process.
6. Actuating device according to one of the preceding claims, characterized in that the rotation locking element (35) is skeletonized by recesses (49).
7. Actuating device according to one of the preceding claims, characterized in that the threaded spindle (27) is manufactured by a cold forming process.
8. Actuating device according to one of the preceding claims, characterized in that the rotation locking element (35) is axially fixed to the threaded spindle (27).
9. Actuating device according to claim 8, characterized in that the threaded spindle (27) or the anti-rotation element (35) has an undercut (50) or an undercut in which the anti-rotation element (35) or the threaded spindle (27) engages for axially fixed connection of the anti-rotation element (35) with the threaded spindle (27).
10. Actuating device according to one of claims 8 and 9, characterized in that the rotation locking element (35) is axially fixedly connected to the threaded spindle (27) by riveting the rotation locking element (35) and / or by riveting the threaded spindle (27).
11. Actuating device according to one of the preceding claims, characterized in that the threaded spindle (27) has a first end section (34) facing the pressure element (3), and that the anti-rotation element (35) is arranged on the first end section (34).
12. Actuating device according to one of the preceding claims, characterized in that the rotation locking element (35) has a has an annular section (61), and that the threaded spindle (27) is inserted into an opening (37) of the annular section (61).
13. Actuating device according to one of the preceding claims, characterized in that the anti-rotation element (35) has at least one radial projection (45) which engages radially in a radial recess (46) of the housing (7) of the actuating device (1) to form the anti-rotation device (44).
14. Actuating device according to claim 13, characterized in that a sliding shoe (48) is arranged on the radial projection (45).
15. Actuating device according to one of the preceding claims, characterized in that the housing (7) is a cylindrical extrusion profile (7).