Braking device for a motor vehicle, method for manufacturing

Abstract

The invention relates to a braking device (1) for a motor vehicle, in particular a brake force generator or brake booster, with an input rod (4) connected to a connecting rod (7) that can be connected to a brake pedal. For this purpose, the input rod (4) is inserted into an axial recess (9) on the end face of the connecting rod (7) and locked in the axial recess (9) by plastic deformation of the connecting rod (7) in the region of the axial recess (9). It is provided that the input rod (4) has a conical end section (11) at its end (6) located in the axial recess in the region of the plastic deformation, with a cross-section, in particular diameter, that increases towards a free end face (12) of the end (6) of the input rod (4).

Description

[0001] The present invention relates to a braking device for a motor vehicle, in particular a brake force generator or brake booster, which is connected to an input rod which is connected to a connecting rod which can be connected to a brake pedal, wherein the input rod is inserted into an axial recess on the front face of the connecting rod and is locked in the axial recess by plastic deformation of the connecting rod in the area of ​​the axial recess.

[0002] Furthermore, the invention relates to a method for manufacturing such a braking device, wherein the input rod is inserted into an axial recess on the end face of the connecting rod and is locked in the axial recess by plastic deformation of the connecting rod in the area of ​​the axial recess. State of the art

[0003] Braking devices of the type mentioned above are known from the prior art. Brake force generators or brake boosters often require a customer-specific connection to a brake pedal to enable their use in different motor vehicles. For this purpose, a customer- or vehicle-specific connecting rod is frequently assigned to the input rod, adapted to the vehicle in which the braking device is to be used. In the past, a screw connection was often used to connect the connecting rod to the input rod. More recent embodiments utilize the plastic deformation of the connecting rod to attach it to the input rod by clinching or crimping. It is known, among other things, to form a circumferential groove in the input rod into which the material of the connecting rod can be pressed. Disclosure of the invention

[0004] The braking device according to the invention has the advantage over known solutions that the plastic deformation of the connecting rod not only achieves the locking mechanism itself, but also a backlash-free connection in the direction of actuation. For this purpose, the invention provides that the input rod has a conical end section at its end located in the axial recess in the area of ​​plastic deformation, with a cross-section, in particular diameter, that increases towards the end of the input rod. Due to the conical shape, during the plastic deformation of the connecting rod, an axial force is generated in addition to the radial force acting on the input rod, which displaces the input rod axially relative to the connecting rod, and thus in the direction of actuation.Because the cross-section of the cone shape widens or increases in size towards the end of the input rod, deformation of the connecting rod causes the input rod to be pushed further into the axial recess. This minimizes, and preferably completely eliminates, any axial play that may exist between the connecting rod and the input rod. Preferably, at least the end section of the input rod has a circular cross-section, so that the size of the cross-section is determined by its diameter.

[0005] The maximum insertion depth is defined or limited, in particular, by the free end face of the connecting rod and the bottom of the axial recess. Alternatively, the connecting rod has an axial stop located outside the connecting rod, which is drawn against the free end face of the connecting rod during the conventional deformation of the connecting rod by the conical geometry. In both cases, a fixed end stop is provided, which is achieved by the advantageous conical shape during deformation of the connecting rod. This ensures that any axial play is overcome in the axial direction through plastic deformation, thereby guaranteeing a permanently secure and play-free connection between the connecting rod and the connecting rod.

[0006] Furthermore, it is preferably provided that the cross-section of the end section increases continuously, at least in certain sections. This results in a wedge-shaped design of the end section, which advantageously interacts with the deformation material of the connecting rod to axially displace the input rod.

[0007] Additionally or alternatively, the cross-section of the end section increases in steps, at least in certain sections. This stepped design offers the advantage of increased axial holding forces. A step in the conical shape creates a contact surface that lies, in particular, in a plane perpendicular to the longitudinal axis of the input rod. This facilitates the transmission of especially high tensile forces. Furthermore, the step prevents the connecting rod from slipping off the input rod and does not impede the closure of the axial gap between the input rod and the connecting rod during plastic deformation, as described above.

[0008] According to a preferred embodiment of the invention, the cone has a cone angle that prevents self-locking in the axial direction during plastic deformation and, in particular, promotes axial displacement. The minimum size of the cone angle is thus limited, in particular, by the self-locking that is to be avoided.

[0009] Furthermore, it is preferably provided that the smallest cross-section of the end section is smaller than the cross-section of the adjoining section of the input rod. This means that the conical shape does not result from an increase in the cross-section along the extension of the input rod, but rather initially leads to a reduction in the cross-section of the input rod before the cross-section increases again due to the conical shape. The step between the section of the input rod and the beginning of the end section creates a step in the input rod. Overall, this ensures that the cross-section of the input rod is not increased in the end region by the conical shape, thus guaranteeing a space-saving and compact design of the braking device.

[0010] Preferably, the largest cross-section of the end section corresponds to the cross-section of the section of the entrance rod adjoining the end section, so that the conical end section lies completely within the cross-section of the entrance rod.

[0011] Furthermore, it is preferably provided that the longitudinal extent of the end section is greater than the longitudinal extent of the axial recess. This ensures that, during deformation of the connecting rod, the material of the connecting rod does not come into contact with the section of the input rod to which the end section connects. This prevents axial forces from arising during the plastic deformation of the connecting rod, which would lead to a displacement of the input rod in the opposite direction to the desired direction.

[0012] The method according to the invention, with the features of claim 9, is characterized in that the entrance rod is provided at its end lying in the axial recess, in the region of plastic deformation, with a conical end section which has a cross-section that increases towards the end of the entrance rod. This results in the advantages already mentioned above.

[0013] Preferably, the plastic deformation of the connecting rod is achieved by clinching or crimping. Known deformation processes can be used for this purpose, which allows for cost-effective manufacturing of the brake assembly.

[0014] Further advantages and preferred features and combinations of features will become apparent in particular from the foregoing and from the claims. The invention will now be explained in more detail with reference to the drawings. To this end, we show... Fig. 1. An advantageous braking device in a simplified representation, Fig. 2 a detailed view of the braking system and Fig. 3 a second detailed view of the advantageous braking device and Fig. 4 another embodiment of the braking device.

[0015] Fig. Figure 1 shows a simplified representation of an advantageous braking device 1 for a motor vehicle not shown in detail here. The braking device 1 comprises a brake module 2, which in this case is designed as an electromechanical brake force generator. This generator serves to adjust, and in particular increase, the hydraulic pressure in a hydraulic brake system depending on the application of the brake pedal. Optionally, the brake module 2 is designed as a brake booster, which amplifies the pedal force applied by a user to the hydraulic brake system.

[0016] The brake module 2 has a controllable actuator 3 which, depending on brake pedal actuation, generates a braking force or hydraulic pressure, or increases the braking force applied by the brake pedal. The brake device 1 has an input rod 4 that can be connected to the vehicle's brake pedal. For this purpose, the input rod 4 projects from a housing 5 of the brake module 2 and has a free end 6. A connecting rod 7 is slid onto the free end 6, and a coupling element 8 is formed at the end of the connecting rod 7, for connecting it to the brake pedal or a brake pedal rod.

[0017] The coupling element 8 is specifically designed to meet individual customer requirements, allowing the brake assembly 1 to be used in different vehicles from different manufacturers by using a suitable connecting rod. In the present embodiment, the coupling element 8 has a spherical shape with a predetermined diameter.

[0018] At its end facing the input rod 4, the connecting rod 7 has an axial recess 9 on its front face, into which the input rod 4 is inserted with its end 6.

[0019] Fig. Figure 2 shows an enlarged detail view of the connection between the input rod 4 and the connecting rod 7 after the input rod 4 has been inserted into the axial recess 9. The axial recess 9 is cylindrical or cup-shaped and projects axially into the connecting rod 7 to a predetermined depth x1, the depth x1 being limited by a bottom 10 of the axial recess 9, which is particularly flat.

[0020] The entrance rod 4 has a conical end section 11 at its end 6. The end section 11 has a cone angle α, which is oriented such that the end section 11 widens towards a free end face 12 at the end 6 of the entrance rod 4 or of the end section 11, or towards the ground 10. The end section 11 can widen up to the free end face 12, as shown by way of example in Fig. 3 shown, or into a cylindrical end, as in Fig. Figure 2, shown as an example, is skipped over. The cross-section of the inlet rod 4 and the end section 11, which is circular in the present embodiment, thus has a diameter that increases along the longitudinal extent of the inlet rod 4. The largest diameter of the end section corresponds to the outer diameter of the inlet rod 4 in the section 13 to which the end section 11 is attached, and the smallest diameter of the end section 11 is smaller than the diameter of this end section 13 of the inlet rod 4. Therefore, viewed axially, the end section 11 lies within the outer circumference of the inlet rod 4 and, in particular, does not project radially from it.

[0021] According to another embodiment, not shown here, at least the largest diameter of the end section 11 is larger than the diameter of the end section 13 of the inlet rod 4, so that the end section projects radially beyond the inlet rod 4, at least in some areas. In any case, however, the largest outer diameter of the end section 11 is preferably smaller than the inner diameter of the axial recess 9, so that the inlet rod 4 with the end section 11 can be inserted into the axial recess 9 with at least substantially no friction until the free end face 12 of the end section 11 rests against the bottom 10 of the axial recess 9.

[0022] The connecting rod 7 is then adjusted in the area of ​​the axial recess 9 by a tool 14, as exemplified in Fig. 3 is shown, plastically deformed to permanently and axially free of play lock the connecting rod 7 to the input rod 4.

[0023] Fig. Figure 3 shows a detailed view of the connection during the joining step. The tool 14 is designed, for example, as a crimping tool or a clinching tool, which radially inwards presses the remaining outer wall of the connecting rod 7 in the area of ​​the axial recess 9, so that it partially engages behind the end section 11 in the axial direction or is pressed into the recess formed by the end section 11. Because the end section 11 widens towards the base 10, the radial indentation of the material of the connecting rod 7 in the area of ​​the end section 11 causes the end 6 of the inlet rod 4 to be forced further into the axial recess 9, as indicated by an arrow in Fig. 3 is shown. This axial force component presses the free end face 12 of the input rod 4 against the base 10 of the connecting rod 7, so that any axial play between these two components of the braking device is overcome and an axially play-free connection is thereby created.

[0024] While in the exemplary embodiment of Fig. 2 the axial recess has an extent x1 that is longer than the longitudinal extent x2 of the end section 11, is in the embodiment of Fig. 3 provided that the longitudinal extent x2 of the end section 11 is at most as large as the longitudinal extent x1 of the axial recess 9, so that the free end of the connecting rod 7 can be inserted into the recess of the input rod 4 created by the end section 11, as shown in Fig. Figure 3 shows that when the connecting rod 7 deforms, it can no longer contact section 13 of the input rod. This has the particular advantage that the free end of the connecting rod 7 does not exert a counterforce on the step formed between section 13 and the end section 11, which could increase axial play between the connecting rod 7 and the input rod 4 or at least counteract the desired minimization of the gap. Preferably, therefore, the longitudinal extent x1 is slightly smaller than the longitudinal extent x2 of the end section 11.

[0025] Fig.Figure 4 shows a further embodiment of the inlet rod 4, which differs from the previous embodiment in that the end section 11, in addition to the increasing diameter of the cone, has several stepped diameter expansions. These stepped expansions 14 form stop surfaces, which are oriented perpendicular to the longitudinal extent or longitudinal axis of the inlet rod 4. These stop surfaces 14 ensure even greater retention of the inlet rod 4 in the assembled state, because the plastically deformed material of the connecting rod 7 can then transmit even higher forces to the end section 11 and thus to the inlet rod 4, without the connecting rod 7 being able to detach from the inlet rod 4.

[0026] The cone angle α is preferably selected such that self-locking is avoided and sliding movement of the input rod 4 relative to the connecting rod 7 is ensured. Additionally, the sliding is preferably supported by a surface coating of the end section 11 and / or the connecting rod 7 in the axial recess 9 with an advantageous coefficient of friction.

Claims

[1] Braking device (1) for a motor vehicle, in particular brake force generator or brake booster, with an input rod (4) which is connected to a connecting rod (7) which can be connected to a brake pedal, wherein the input rod (4) is inserted into an axial recess (9) on the front face of the connecting rod (7) and is locked in the axial recess (9) by plastic deformation of the connecting rod (7) in the area of ​​the axial recess (9), characterized by , that the inlet rod (4) has a conical end section (11) at its end (6) lying in the axial depression in the area of ​​plastic deformation, with a cross-section, in particular diameter, increasing in the direction of a free end face (12) of the end (6) of the inlet rod (4). [2] Braking device according to claim 1, characterized by, that the penetration depth of the entry rod (4) into the axial recess is limited by the end face (12) of the end section (11) and a bottom (10) of the axial recess (9). [3] Braking device according to one of the preceding claims, characterized by , that the cross-section of the end section (11) increases continuously, at least section by section. [4] Braking device according to one of the preceding claims, characterized by , that the cross-section of the end section (11) increases in a step-like manner, at least section by section. [5] Braking device according to one of the preceding claims, characterized by , that a cone angle (α) of the end section (11) is chosen such that it prevents self-locking in the axial direction. [6] Braking device according to one of the preceding claims, characterized by, that the smallest cross-section, in particular diameter, of the end section (11) is smaller than the cross-section of an adjoining section (13) of the inlet rod. [7] Braking device according to one of the preceding claims, characterized by , that the largest cross-section, in particular diameter, of the end section (11) corresponds to the cross-section of the section (13) of the inlet rod (4) adjoining the end section (11). [8] Braking device according to one of the preceding claims, characterized by , that the longitudinal extent (x2) of the end section (11) is greater than the longitudinal extent (x1) of the axial depression (9). [9] Method for manufacturing a braking device according to any one of claims 1 to 8, wherein the input rod (4) is inserted into an end-face axial recess (9) of the connecting rod (7) and is locked in the axial recess (9) by plastic deformation of the connecting rod (7) in the area of ​​the axial recess (9), characterized by , that the entrance rod (4) is provided at its end (6) lying in the axial recess (9) in the area of ​​plastic deformation with a conical end section (11) which has a cross-section, in particular diameter, that increases in the direction of a free end face (12) of the entrance rod (4).

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