Connection assembly, brake actuator having a connection assembly of this kind, and method for producing a connection assembly
Patent Information
- Application Number
- PCT/EP2026/056887
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-27
- Filing Date
- 2026-03-12
- Publication Date
- 2026-10-01
Smart Images
Figure EP2026056887_01102026_PF_FP_ABST
Abstract
Description
[0001] R. 418397
[0002] - 1 -
[0003] Description
[0004] title
[0005] Connection arrangement, brake actuator with such a connection arrangement and method for producing a connection arrangement
[0006] The invention relates to a connection arrangement between a shaft component and a plate of a brake actuator for a motor vehicle. The invention also relates to a brake actuator for a motor vehicle with such a connection arrangement and to a method for producing a friction-fit and positive-fit connection between a shaft component and a plate of a brake actuator for a motor vehicle.
[0007] State of the art
[0008] Conventional electromechanical brake boosters or brake actuators have a pre-assembled assembly consisting of an anti-rotation plate and a spindle connected thereto, wherein the anti-rotation plate includes a central opening which essentially corresponds to a diameter of the tubular spindle and the spindle is welded to the anti-rotation plate at an axial end section in the area of the central opening.
[0009] Solutions are also known that avoid welding the spindle. For example, DE 102017214609 A1 describes a method for creating a positive-locking connection between a shaft component and a plate of a brake booster for a motor vehicle, wherein a forming punch is inserted into the shaft component in the area of a second axial R. 418397
[0010] - 2 -
[0011] The second axial section is inserted into the shaft component for at least partial deformation of the second axial section to form a positive-locking connection between the shaft component and the plate of the brake booster.
[0012] Furthermore, DE 102003054864 A1 describes a spindle to whose free end a coupling part is permanently attached, wherein the coupling part has at least two sections, namely a receiving section which is designed to receive a nipple of a cable pull, and a fastening section with which the coupling part is attached to the free end of the spindle. In particular, the fastening section is crimped to the free end section of the spindle.
[0013] However, the known solutions lack an extremely reliable connection that can be positioned in the very limited installation space of a brake booster and manufactured cost-effectively.
[0014] Disclosure of the invention
[0015] The invention provides a connection arrangement of a shaft component and a plate of a brake actuator with the features of claim 1, a brake actuator for a motor vehicle with the features of claim 6, and a method for producing a force-fit and form-fit connection between a shaft component and a plate of a brake actuator for a motor vehicle with the features of claim 7.
[0016] According to a first aspect of the invention, a connection arrangement is provided for a shaft component and a plate of a brake actuator for a motor vehicle. The connection arrangement comprises the shaft component, which has an axial end section, and the plate with a recess for receiving the axial end section. The axial end section and the recess each have a complementary shape. R. 418397
[0017] - 3 -
[0018] The plate has a wave-like surface structure. It is connected to the axial end section of the shaft component by a positive-locking connection in one circumferential direction, preventing rotation. Furthermore, the plate forms a friction-locking connection with the shaft component in one axial direction.
[0019] According to a second aspect of the invention, a brake actuator for a motor vehicle is provided. The brake actuator comprises a push rod, an axially displaceable piston, and a master brake cylinder. Furthermore, the brake actuator includes a connection arrangement according to the first aspect of the invention, wherein the shaft component is operatively connected to the axially displaceable piston via the push rod such that a translational movement of the shaft component causes an axial displacement of the piston relative to the master brake cylinder.
[0020] According to a third aspect of the invention, a method is provided for producing a friction-fit and form-fit connection between a shaft component and a plate of a brake actuator for a motor vehicle. The method comprises the following steps:
[0021] - Providing the shaft component and the plate, wherein the shaft component has an axial end section and the plate has a recess for receiving the axial end section. The axial end section and the recess each have a complementary, wave-shaped surface structure.
[0022] - Joining the shaft component and the plate, wherein the axial end section of the shaft component and the plate are joined with clearance, so that they form a positive-locking connection in one circumferential direction of the shaft component. - Widening the axial end section such that the plate forms a force-locking connection with the shaft component in one axial direction.
[0023] One of the underlying ideas of the present invention is to create a connection between the shaft component and the plate of the brake actuator, which, through clearance joining, allows for simple and cost-effective manufacturing and preparation of the two joining partners as R. 418397
[0024] - 4 -
[0025] This single component enables a robust and durable connection arrangement. By expanding the internal geometry of the axial end section until it abuts the plate, the need for a custom fit is eliminated. Before expansion, the plate and the shaft component exhibit a radial air gap, particularly during joining, which is closed by the expansion process. Furthermore, the brake actuator components interacting with the shaft component and the plate can be used virtually unchanged. Therefore, no new component designs are required. Additionally, post-processing of the individual parts or components prior to joining is unnecessary.
[0026] For the purposes of this application, the term "wave-shaped surface structure" includes in particular surfaces that are wave-shaped, zigzag-shaped or have other curves or indentations.
[0027] The plate can be essentially planar. Furthermore, the plate can be axially symmetric. The shaft component can be essentially rotationally symmetric. The shaft component can be tubular, having at least a partial, and in particular a continuous, hollow bore in the axial direction.
[0028] The connection arrangement according to the invention, and in particular its manufacturing process, reduces the costs of individual components, maintenance and failure costs, as well as the one-time investment costs for series production. The present invention thus provides a cost-effective and reliable connection within very limited available installation space.
[0029] A significant advantage of the connection arrangement according to the invention is that it increases robustness against the effects of media residues or contaminants in the contact area of the two connecting or joining partners. Furthermore, R. 418397
[0030] - 5 -
[0031] Increased robustness can be used to optimize the surface of at least one component of the two connecting partners for further properties.
[0032] Furthermore, with the present invention, boundary conditions can be better investigated in advance using boundary patterns, since these mainly involve geometric influencing factors, in particular the mutually complementary, wave-like surface structure. In comparison, many uncertainties come into play with a welded joint, which cannot be completely guaranteed. For example, holes can occur in the weld seam due to media residues in the joint. A subsequent discovery of such a hole can lead to the rejection of the assembly and thus to costly errors.
[0033] Another advantage is that a wide variety of material pairings are possible for the connection arrangement according to the invention, in particular also non-weldable materials.
[0034] Advantageous designs and further developments result from the further sub-claims as well as from the description with reference to the figures in the drawing.
[0035] According to a further development of the invention, the complementary, wave-shaped surface structure on the axial end section and on the recess is each designed as a knurling for the positive locking connection in the circumferential direction. In other words, the positive locking connection can be described as a double knurling. The knurling on the shaft component can be produced, for example, by pendulum broaching.
[0036] According to a further embodiment of the invention, the plate has a thickness of approximately 2.2 mm or less. This small thickness makes the plate easier to shape or even to convert into a blank. 418397
[0037] - 6 -
[0038] To form a suitable shape according to the limited installation space within the brake actuator. Compared to connecting the plate to the shaft component using a laser weld, the same requirements for the transmitted torque can be met with one-third less axial installation space. For example, the plate can have a thickness of approximately 2 mm. The plate can have the aforementioned thicknesses, particularly in the area of the recess.
[0039] According to a further embodiment of the invention, the plate is designed as an anti-rotation plate of the brake actuator and the shaft component as a spindle. For example, the spindle can be mounted in a translation-free manner. The translation-free spindle engages, for example, with a worm gear, the worm gear being driven by a worm shaft. Thus, a component already proven for the intended application, such as the worm drive, can be used and, if necessary, adapted.
[0040] This can reduce the need for costly new developments and / or reduce the number of additional components to the minimum necessary.
[0041] According to a further embodiment of the invention, the shaft component is coated with a sliding coating and / or a corrosion inhibitor. The sliding coating can improve the lubrication of the shaft component. In particular, the shaft component can be completely coated with the sliding coating, including the axial end section. This results in increased robustness of the connection arrangement according to the invention with regard to the effects of media residues or contaminants, for example, from a corrosion inhibitor on the surface in the contact area of the two joining partners or from coating residues that are drawn into the recess by punching a pre-coated material.
[0042] According to a further embodiment of the invention, when widening the axial end section, an outer diameter of the axial end section is radially widened by rolling on an inner wall of the axial end section. For example, an internal rolling tool can be inserted into the axial end section. R. 418397
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[0044] which is hollow-drilled, is inserted and acts radially on the inner wall.
[0045] In particular, a radial force can be applied to the inner wall until the axial end section rests radially against the plate, with contact being detected upon reaching or exceeding a predetermined starting force. This means that the play or radial air gap between the axial end section and the plate is eliminated by internally rolling the axial end section until the predetermined starting force is reached or exceeded. Once the axial end section rests radially against the plate, or the predetermined starting force is reached or exceeded, a predetermined rolling force can be applied to force-fit the axial end section to the plate.
[0046] According to a further embodiment of the invention, the recess in the plate is produced in a single manufacturing process, in particular a single punching process. Punching has the advantage that the tooth shape itself remains unchanged over the tool life. Thus, only a single manufacturing process can be used to produce the recess instead of several manufacturing steps, for example, pre-punching and subsequent machining. Therefore, it is possible to dispense with the production of a fitting, since the method according to the invention can cope with less precise geometries in the joining area, i.e., in the axial end section and the recess – as long as the geometries are consistently too large or too small, but their shape still corresponds to the shape of the complementary counterpart.
[0047] According to a further embodiment of the invention, the method also comprises a step of forming an end of the shaft component that projects axially from the plate, so that the formed end additionally connects the plate in the axial direction by means of a positive locking mechanism. In this way, the force-fit connection in the axial direction can be secured by the positive locking mechanism. R. 418397
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[0049] The axial connection between the plate and the shaft component can be made even more reliable. For example, the end protruding axially from the plate can be crimped or reshaped in a similar way.
[0050] As an alternative to riveting, a positive fit can be achieved by material displacement in the form of an undercut when lower axial loads need to be transmitted. For example, the shaft component can be expanded until the material rests against the cutout.
[0051] It would be more reliable not to rely on the punching breakout, but to actively emboss a chamfer onto the plate, into which the material for the undercut is then deformed.
[0052] The invention will now be explained with reference to the figures in the drawings. The figures show:
[0053] Fig. 1 shows a schematic sectional view of a section of a brake actuator for a motor vehicle according to an embodiment of the present invention;
[0054] Fig. 2 shows a schematic view of a connection arrangement of a shaft component and a plate of a brake actuator viewed in an axial direction according to a further embodiment of the present invention;
[0055] Fig. 3A shows a schematic view of the shaft component and the plate of the connection arrangement from Fig. 2 viewed in a radial direction before they are joined;
[0056] Fig. 3B shows a schematic view of the shaft component and the plate from Fig.
[0057] 3A viewed in a radial direction after they have been joined;
[0058] Fig. 4A shows a schematic view of the shaft component and the plate from Fig.
[0059] 3B viewed in an axial direction after they have been joined; R. 418397
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[0061] Fig. 4B shows a schematic view of the shaft component and the plate from Fig.
[0062] 4A viewed in an axial direction after the axial end section has been widened;
[0063] Fig. 5 shows an enlarged detail view of the connection arrangement from Fig.
[0064] 3B, wherein an axially projecting end of the shaft component from the plate was formed; and
[0065] Fig. 6 shows a flowchart of a method for producing a force-locking and form-locking connection between a shaft component and a plate of a brake actuator for a motor vehicle according to a further embodiment of the present invention.
[0066] In the figures, the same reference symbols denote identical or functionally equivalent components, unless otherwise stated.
[0067] For the purposes of this application, the term "wave-shaped surface structure" refers to all surfaces that are wave-shaped, zigzag-shaped, or have other curves or indentations.
[0068] Fig. 1 shows a schematic sectional view of a section of a brake actuator 1 for a motor vehicle according to an embodiment of the present invention.
[0069] The brake actuator 1, schematically depicted in Fig. 1, can be used on a vehicle / motor vehicle, and the usability of the brake system with the brake actuator 1 is not limited to any specific vehicle type / motor vehicle. The brake actuator 1 is shown by way of example as an electromechanical brake actuator, but can also be any type of motorized brake actuator. R. 418397
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[0071] The exemplary brake actuator 1 comprises a motor (not shown), a master brake cylinder (not shown), an axially displaceable piston for pressure build-up in a pressure chamber of the master brake cylinder, and a push rod. The brake actuator 1 also includes a connection between a shaft component 10 and a plate 20. The shaft component 10 is exemplary in its configuration as a spindle. The plate 20 is exemplary in its configuration as an anti-rotation plate. The motor and the spindle 10 form a drive train. The exemplary drive train can further comprise, for example, a motor-driven worm shaft and a drive-side worm gear 2. The motor-driven worm shaft can drive the drive-side worm gear. The worm gear 2 can drive the spindle 10. The drive train can, for example, move the mechanically attached piston relative to the master brake cylinder to pump brake fluid.The piston controls the volume flow of the brake fluid.
[0072] The spindle 10 is operatively connected to the axially displaceable piston via the push rod in such a way that a translational movement of the spindle causes an axial displacement of the piston relative to the master brake cylinder. The anti-rotation plate 20 can secure the spindle 10 against rotation relative to a housing 3 of the brake actuator 1.
[0073] The spindle 10 has an axial end section 11. The anti-rotation plate 20 includes a recess 21 for receiving the axial end section 11, wherein the axial end section 11 and the recess 21 each have a complementary, wave-shaped surface structure DR. The anti-rotation plate 20 is rotationally fixed to the axial end section 11 by a positive-locking connection in one circumferential direction of the spindle 10. Furthermore, the anti-rotation plate 20 is also force-locked to the spindle 10 in an axial direction X. R. 418397
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[0075] A key advantage of the described brake actuator 1 is that it requires no modifications to existing brake systems. No intervention in the hydraulics is necessary. The described brake actuator 1 is compatible with conventional master brake cylinders.
[0076] Fig. 2 shows a schematic view of a connection arrangement 1 of a shaft component 10 and a plate 20 of a brake actuator 1 viewed in an axial direction X according to a further embodiment of the present invention.
[0077] The connection assembly comprises the shaft component 10 and the plate 20. The shaft component 10 has an axial end section 11. The plate 20 has a recess 21 for receiving the axial end section 11. The axial end section 11 and the recess 21 each comprise a complementary, wave-shaped surface structure DR. For example, the complementary, wave-shaped surface structure DR on the axial end section 11 and on the recess 21 can each be designed as a knurling for the positive locking connection in the circumferential direction, as shown in Fig. 2.
[0078] The plate 20 is rotationally fixed to the axial end section 11 of the shaft component 10 by a positive-locking connection in one circumferential direction of the shaft component 10. Additionally, the plate 20 forms a force-locking connection with the shaft component 10 in an axial direction X. The plate 20 can be axially symmetrical. The shaft component 10 can be substantially rotationally symmetrical. The shaft component 10 can have at least a partial hollow bore in the axial direction, into which a view can be seen in Fig. 2. The hollow bore is at least deep enough that the geometry to be formed is exposed on the inside of the hollow-bored section of the shaft component 10. An outer diameter d11 of the axial end section 11 can correspond to a diameter of the recess 21. R. 418397
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[0080] Fig. 3A shows a schematic view of the shaft component 10 and the plate 20 of the connection arrangement from Fig. 2, viewed in a radial direction before they are joined. This means that the shaft component 10 and the plate 20 are illustrated here as separate components, namely the two joining partners.
[0081] For example, the plate 20 can have a thickness t20 of approximately 2.2 mm or less. In particular, the plate 20 can have a thickness t20 of approximately 2 mm. The plate 20 can have the aforementioned thicknesses t20, especially in the area of the recess 21. Due to this small thickness t20, or plate thickness, the plate 20 is easier to form or even to shape into a suitable form corresponding to the limited installation space within the brake actuator.
[0082] By way of example, the plate 20 is designed here as an anti-rotation plate of the brake actuator 1 and the shaft component 10 as a spindle. For example, the spindle 10 can be mounted without translation. In Fig. 2, the axial direction X corresponds, for example, to an axis of symmetry of the plate 20 and to an axis of rotation of the shaft component 10. The plate 20 can have at least one projection, in particular two projections, which extends from the plate 20 in the axial direction X.
[0083] Furthermore, the shaft component 10 can be coated with a sliding lacquer and / or a corrosion inhibitor. In particular, the shaft component 10 can be completely coated with the sliding lacquer, i.e., also in the axial end section 11. This results in increased robustness of the connection arrangement according to the invention with regard to the effects of media residues or contaminants, for example, by a corrosion inhibitor on the surface DR in the contact area of the two joining partners or by coating residues that are drawn into the recess 21 by punching a pre-coated material. R. 418397
[0084] - 13 -
[0085] Fig. 3B shows a schematic view of the shaft component 10 and the plate 20 from Fig. 3A viewed in a radial direction after they have been joined.
[0086] Specifically, Fig. 3B shows the state of the connection arrangement after the axial end section 11 of the shaft component 10 and the plate 20 have been joined with clearance, so that they form a positive-locking connection in one circumferential direction of the shaft component 10. In particular, the recess 21 and the axial end section 11 have a radial air gap, which is illustrated more clearly in Fig. 4A.
[0087] Fig. 4A shows a schematic view of the shaft component 10 and the plate 20 from Fig. 3B viewed in an axial direction after they have been joined.
[0088] Figure 4A shows that the complementary, wave-like surface structure DR of the two joining partners 10 and 20 interlock and form a positive fit in the circumferential direction. This means that the wave-like component 10 cannot be rotated relative to the plate 20. The radial air gap LS is chosen to be so small that the wave-like surface structure DR interlocks, but no tight fit is necessary for the joining process.
[0089] Fig. 4B shows a schematic view of the shaft component 10 and the plate 20 from Fig. 4A viewed in an axial direction after the axial end section 11 has been widened.
[0090] Here, the plate 20 forms a force-fit connection with the shaft component 10 in an axial direction X. This means that the clearance LS, or the air gap, between the axial end section 11 and the plate 20 has been eliminated by widening the axial end section 11 and pressing it radially against the plate 20.
[0091] For example, the axial end section 11 can be radially widened by rolling on an inner wall of the axial end section 11. R. 418397
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[0093] For example, an internal rolling tool can be inserted into the hollow axial end section 11 and act radially on the inner wall. Specifically, a radial force can be applied to the inner wall until the axial end section 11 abuts radially against the plate 20, with contact being detected upon reaching or exceeding a predetermined starting force. This means that the clearance LS, or air gap, between the axial end section 11 and the plate 20 is eliminated by internally rolling the axial end section 11 until the predetermined starting force is reached or exceeded. When the axial end section 11 abuts radially against the plate 20, or when the predetermined starting force is reached or exceeded, a predetermined rolling force F_Roll can forcefully connect the axial end section 11 to the plate 20.
[0094] Fig. 5 shows an enlarged detail view of the connection arrangement from Fig. 3B, in which an axially projecting end of the shaft component from the plate has been formed. In particular, the axial end section 11 and the plate 20 in the area of the recess 21 are greatly enlarged.
[0095] Here, an end 12 of the shaft component 10, projecting axially from the plate 20, is formed such that the formed end 12 additionally connects the plate 20 in the axial direction X in a positive-locking manner. For example, the end 12 projecting axially from the plate 20 can be riveted or formed in a similar way.
[0096] Fig. 6 shows a flowchart of a method for producing a force-locking and form-locking connection between a shaft component 10 and a plate 20 of a brake actuator 1 for a motor vehicle according to a further embodiment of the present invention.
[0097] The procedure includes, for example, a provision step M1, a joining step M2, a widening step M3, and an optional forming step M4.R. 418397
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[0099] In step M1, the shaft component 10 and the plate 20 are provided. The shaft component 10 has an axial end section 11. The plate 20 has a recess 21 for receiving the axial end section 11. The axial end section 11 and the recess 21 each have a complementary, wave-shaped surface structure DR. The recess 21 of the plate 20 can be produced, for example, by a single manufacturing process, in particular by a single stamping process.
[0100] In step M2, the shaft component 10 and the plate 20 are joined, wherein the axial end section 11 of the shaft component 10 and the plate 20 are joined with clearance LS, so that they form a positive locking connection in a circumferential direction of the shaft component 10.
[0101] In step M3, the axial end section 11 is expanded such that the plate 20 forms a force-fit connection with the shaft component 10 in an axial direction X. For example, the outer diameter d11 of the axial end section 11 can be radially expanded by rolling an inner wall of the axial end section 11. For this purpose, an internal rolling tool can be inserted into the hollow axial end section 11 and act radially on the inner wall. In particular, a radial force can be exerted on the inner wall until the axial end section 11 abuts radially against the plate 20, whereby the abutment is detected when a predetermined starting force is reached or exceeded.This means that the play LS, or air gap, between the axial end section 11 and the plate 20 is eliminated by internally rolling the axial end section 11 until the predetermined starting force is reached or exceeded. When the axial end section 11 is radially in contact with the plate 20, or when the predetermined starting force is reached or exceeded, the axial end section 11 can be positively connected to the plate 20 by a predetermined rolling force F_Roll. R. 418397.
[0102] - 16 -
[0103] In optional step M4, an end 12 of the shaft component 10 projecting axially from the plate 20 can be formed so that the formed end 12 additionally connects the plate 20 in the axial direction X by means of a positive locking mechanism. In this way, the force-fit connection in the axial direction can be secured by the positive locking mechanism. For example, the end 12 projecting axially from the plate 20 can be riveted or formed in a similar manner.
[0104] Although the present invention has been explained above by way of example embodiments, it is not limited to these, but can be modified in many ways. In particular, combinations of the preceding embodiments are also conceivable.
Claims
R. 418397 - 17 - Claims 1. Connection arrangement of a shaft component (10) and a plate (20) of a brake actuator (1) for a motor vehicle, comprising: the shaft component (10) which has an axial end section (11); and the plate (20) with a recess (21) for receiving the axial end section (11), wherein the axial end section (11) and the recess (21) each have a complementary, wave-shaped surface structure (DR); wherein the plate (20) is connected to the axial end section (11) of the shaft component (10) by a positive locking connection in a circumferential direction of the shaft component (10) in a rotationally fixed manner and wherein the plate (20) furthermore forms a force-fit connection with the shaft component (10) in an axial direction (X).
2. Connection arrangement according to claim 1, wherein the mutually complementary, wave-shaped surface structure (DR) is formed as a knurling for the positive locking connection in the circumferential direction on the axial end section (11) and on the recess (21).
3. Connection arrangement according to claim 1 or 2, wherein the plate (20) has a thickness (t20) of about 2.2 mm or less.
4. Connection arrangement according to one of the preceding claims, wherein the plate (20) is configured as an anti-rotation plate of the brake actuator (1) and the shaft component (10) is configured as a spindle. R. 418397 - 18 - 5. Connection arrangement according to one of the preceding claims, wherein the shaft component (10) is coated with a sliding varnish and / or a corrosion protection agent.
6. Brake actuator (1) for a motor vehicle, comprising: a push rod; an axially displaceable piston; a master brake cylinder; and a connection arrangement according to one of the preceding claims, wherein the shaft component (10) is operatively connected to the axially displaceable piston via the push rod in such a way that a translational movement of the shaft component (10) causes an axial displacement of the piston relative to the master brake cylinder.
7. Method for producing a force-fit and form-fit connection between a shaft component (10) and a plate (20) of a brake actuator (1) for a motor vehicle, comprising the steps: Providing (M1) the shaft component (10) and the plate (20), wherein the shaft component (10) has an axial end section (11) and the plate (20) has a recess (21) for receiving the axial end section (11), wherein the axial end section (11) and the recess (21) each have a complementary, wave-shaped surface structure (DR); Joining (M2) the shaft component (10) and the plate (20), wherein the axial end section (11) of the shaft component (10) and the plate (20) are joined with clearance (LS) so that they form a positive-locking connection in a circumferential direction of the shaft component (10); and Widening (M3) of the axial end section (11) such that the plate (20)R. 418397 - 19 - forms a force-fit connection with the shaft component (10) in an axial direction (X).
8. Method according to claim 7, wherein when widening (M3) the axial end section (11) an outer diameter (d11 ) of the axial end section (11) is radially widened by rolling on an inner wall of the axial end section (11).
9. Method according to claim 7 or 8, wherein during provision (M1) the recess (21) of the plate (20) is produced in the plate (20) by a single manufacturing process, in particular by a single punching process.
10. Method according to one of claims 7 to 9, further comprising a step forming (M4) an end (12) of the shaft component (10) projecting axially from the plate (20), such that the formed end (12) additionally connects the plate (20) in the axial direction (X) in a form-fitting manner.