Brake pad group and vehicle brake

Abstract

The invention relates to a brake pad set and a vehicle brake. A brake pad pack (22) for a disc brake is disclosed that includes an inner brake pad (24) and an outer brake pad (26). In this case, each brake lining (24, 26) has a backing plate (28) and a brake lining (30, 32), which is mounted on the backing plate (28) and is in contact with the brake rotor during operation. The inner brake lining (30) and the outer brake lining (32) differ in size and preferably also in geometry in plan view, the wear volume of the inner brake pad (24) and the wear volume of the outer brake pad (26) differing by less than 10%. The invention further relates to a vehicle brake (10) having such a brake pad pack (22).

Description

TECHNICAL FIELD

[0001] The invention relates to a brake pad set for a disc brake, comprising an inner brake pad and an outer brake pad, wherein each brake pad has a back plate and a brake lining, the brake lining being mounted on the back plate and coming into contact with the brake disc during operation. Furthermore, the invention relates to a vehicle brake comprising a brake caliper, a brake carrier, an actuator unit and such a brake pad set, the brake rotor reaching into the brake carrier. BACKGROUND

[0002] Generally, the brake linings of the inner brake pad and the outer brake pad are not distinguished from each other, so that the brake linings have approximately the same dimensions. In this case, the outer brake pad is axially held on the brake caliper by two abutment extensions and is correspondingly supported by these two abutment extensions during a braking operation. In contrast, the inner brake pad is acted upon by a brake piston, which generally engages in the center of the brake pad.

[0003] Thus, the central region of the inner brake pad, in particular the brake lining of the inner brake pad, is subjected to significantly greater pressure than the outer region of the inner brake pad, which is not acted upon directly by the brake cylinder. In other words, there is thus greater wear in the region of the brake piston. As a result, the brake lining that is heavily worn protrudes in the region adjacent to the contact surface with the brake piston towards the brake rotor and, as a result, the outer brake pad region of the inner brake pad can remain in contact with the brake rotor when the vehicle brake is released. As a result, a so-called residual brake torque is present. Furthermore, the friction of the outer brake pad region on the brake rotor can lead to a noise that is annoying for the occupants.

[0004] Furthermore, the wear of the brake linings and the force distribution are not uniform as a result of the action of the individual cylinder, which makes it impossible to ensure a completely uniform brake force over the entire surface. This is a problem in particular in the case of electromechanical brakes, since these have large brake pads with large brake linings and a relatively small brake piston.

[0005] In order to achieve a more uniform force distribution during a braking operation, force distributors are generally used, which are intended to distribute the force applied by the brake piston uniformly over the brake pad. However, these components are heavy and require additional installation space. SUMMARY

[0006] It is therefore an object of the invention to provide a brake pad set which allows an improved force distribution and thus a uniform wear of the brake linings. Furthermore, it is an object of the invention to provide a vehicle brake which uses such a brake pad set.

[0007] According to the application, this object is achieved by a brake pad set for a disc brake, which comprises an inner brake pad and an outer brake pad. In this case, each brake pad has a back plate and a brake lining, which is mounted on the back plate and comes into contact with the brake rotor during operation. The inner brake pad and the outer brake pad differ in size in plan view and preferably also in geometry, wherein the wear volume of the inner brake pad and the wear volume of the outer brake pad differ by less than 10%. In other words, the inner brake pad and the outer brake pad differ in size in plan view and have a different geometry, while the wear volume remains almost the same. Here, the difference in size and geometry of the brake linings in plan view, i.e. viewed towards the friction surface, exceeds the production tolerances.

[0008] Furthermore, according to the application, this object is achieved by a vehicle brake, in particular an electromechanical vehicle brake, which comprises a brake caliper, a brake carrier, an actuator unit and the above-mentioned brake pad set, into which the brake rotor projects.

[0009] The difference in size and shape of the inner brake pad and the outer brake pad results in an optimized force distribution during braking operation and thus in each case the entire brake lining of the brake pad is acted upon. As a result, areas with locally higher wear are prevented. As a result, there is no longer a need for a force distributor to distribute the force applied by the brake piston evenly to the brake pad, so that installation space, weight and costs can be saved. Furthermore, the almost equal wear volume ensures that the wear of the inner brake pad and the outer brake pad differs almost not at all, so that resources are saved.

[0010] Since according to the application the size and shape of the brake linings is only changed in plan view, the back plate remains unchanged compared to previous back plates. This has the advantage that a switch to the brake pad set according to the application can be made at any time and that any disc brake can also be retrofitted with the brake pad set according to the application.

[0011] Therefore, preferably in the brake pad set according to the application, only the brake linings are modified, that is to say only the size and shape of the brake linings in plan view is changed, so that the back plate remains unchanged and continues to be usable in already installed vehicle brakes. Therefore, even in already installed vehicle brakes, the optimized brake pad set can be used without any problems, without resulting in higher costs for the vehicle owner or vehicle purchaser, since only the brake pad set and not the entire vehicle brake has to be replaced.

[0012] According to one preferred embodiment, the brake lining of the inner brake pad is designed square or circular in plan view. Additionally or alternatively, the brake lining of the outer brake pad can have an arcuate shape or a rectangular shape in plan view. The idea behind this is to adapt the shape of the brake lining in plan view to the shape of the force application device. It is important here that the best possible shape corresponds to the shape of the brake cylinder and the shape of the abutment extensions for the inner brake pad and the outer brake pad. The brake cylinder is substantially circular, so the best possible shape of the inner brake pad is therefore circular. However, a square inner brake pad also more closely resembles the shape of the brake cylinder than an elongated rectangular shape, which is not directly subjected to the force of the brake cylinder on the outer side of the brake pad. Since the outer brake pad is acted upon by two abutment extensions, it is preferably rectangular or arcuate in order to ensure that the two abutment extensions have sufficient space to apply force on the brake pad or brake lining.

[0013] Preferably, the brake lining of the outer brake pad has a larger area in plan view than the brake lining of the inner brake pad. In particular, the outer brake pad has a brake lining which has an area which is at least 10% larger, preferably between 20% and 300% larger. Since the inner brake pad is subjected to the brake force only at a single location, it can be made smaller in comparison to the outer brake pad, which is supported at two locations by the abutment extensions. In order to ensure a uniform force distribution, the outer brake pad must accordingly be larger than the inner brake pad.

[0014] Since the wear volume of the inner brake pad and the wear volume of the outer brake pad should differ by less than 10%, the brake lining of the inner brake pad can be thicker than the brake lining of the outer brake pad. If the area of the inner brake pad is reduced, its thickness must be increased in order to keep the wear volume as constant as possible. Since the wear volumes are approximately equal, the inner brake pad and the outer brake pad thus wear uniformly, so both brake linings must be replaced at approximately the same time. Thus, since the inner brake pad and the outer brake pad exhibit similar wear, a waste of material can be prevented by the approximately constant wear volume. Since, in order to achieve a mechanical connection between the back plate and the friction lining, the brake lining can in some cases protrude into recesses in the back plate, or the back plate can have small extensions around which the friction material is present, it is not only dependent on the friction lining volume, but also on its predetermined wear volume, which extends, for example, to the first point of contact of the back plate with the brake rotor and begins with a new brake lining.

[0015] According to the application, the thickness of the friction lining is understood to mean the dimension of the brake lining in the axial direction from the back plate.

[0016] According to another embodiment, the back plate of the inner brake pad is thicker than the back plate of the outer brake pad. Alternatively, the thickness of the back plate of the inner brake pad is the same as the thickness of the back plate of the outer brake pad. The thicker back plate allows the brake lining of the inner brake pad to be pressed more firmly against the brake rotor, thereby achieving a constant or higher braking effect despite the smaller area or size of the brake lining.

[0017] According to a preferred embodiment, the brake lining of the outer brake pad is divided into two parts. In other words, the brake lining of the outer brake pad has a gap in the region of the gap between the two adjacent extensions. This prevents higher wear in the central portion of the outer brake disc, as this region is no longer affected by the two adjacent extensions.

[0018] The brake lining of the outer brake pad and the brake lining of the inner brake pad can be made of different materials. In this case, the brake lining material for each brake pad is selected based on different requirements. Therefore, the inner and outer brake linings can differ in terms of material friction coefficient and hardness. In this case, the outer brake lining typically has a higher coefficient of friction than the inner brake lining, thereby also preventing, for example, thermal stress cracks in the brake lining.

[0019] As an alternative to the preferred square or circular shape of the inner brake lining in plan view, the inner brake lining may also have an approximately square rectangular shape or an arcuate shape. In this case, the rectangular shape of the inner brake lining preferably has a width-to-height ratio of less than or equal to 3:2, in particular less than or equal to 4:3, and particularly preferably less than or equal to 5:4.

[0020] If the inner brake lining has an arcuate shape, the width of the brake lining at the radial height where the center axis of the brake cylinder is located is used as the width.

[0021] Optionally, the ratio of the height (radial dimension) to the width of the brake lining of the inner brake pad is between 0.6 and 1.1. From this ratio, it is clear that the inner brake lining is designed to have a slightly square shape. It is important to note that this shape factor applies only to the inner brake lining.

[0022] According to one embodiment, the brake lining of the inner brake pad and the brake lining of the outer brake pad are arranged at different radial heights relative to the brake rotor. This ensures that the centers of force applied to the inner and outer brake pads are located at the same radial height of the brake rotor. This ensures optimal braking power or braking characteristics.

[0023] As mentioned above, this object is also achieved according to the invention by a vehicle brake.

[0024] Preferably, the actuator unit of the vehicle brake engages centrally on the inner brake pad. Furthermore, the brake caliper can have an abutment extension on which the back plate of the outer brake pad is supported by means of a rear contact surface when the brake is activated. In contrast, the inner brake pad can have a rear contact surface which, when viewed in the axial direction, is located between the contact surface of the outer back plate which is in contact with the abutment extension and the actuator unit, in particular the brake cylinder. BRIEF DESCRIPTION OF DRAWINGS

[0025] Further features and advantages will be found in the following description with reference to the drawings. In the drawings:

[0026] Figure 1 a perspective view of a vehicle brake according to the application is shown;

[0027] Figure 2 a perspective view of the outer side of the vehicle brake shown in Figure 1 Fig. 1 is shown without the brake caliper and without the actuator unit, so that the brake pad set according to the application can be seen;

[0028] Figure 3 a perspective view of the inner side of the vehicle brake shown in Figure 1 Fig. 2 is shown without the brake caliper and without the actuator unit;

[0029] Figure 4 a plan view of the vehicle brake shown in Figure 1 Fig. 3 is shown without the brake caliper and the actuator unit;

[0030] Figure 5 a schematic view of the inner brake pad; and

[0031] Figure 6 a schematic view of the outer brake pad. DETAILED DESCRIPTION

[0032] Figures 1 to 4 a vehicle brake 10 with an actuator unit 12 is shown, preferably an electromechanical actuator unit.

[0033] Here, the vehicle brake 10 is a disc brake and is assigned to a wheel of a vehicle.

[0034] In addition to the actuator unit 12, the vehicle brake comprises a brake housing 14 with a brake caliper 16 and a brake carrier 18, by means of which the vehicle brake 10 is fixed to the body of the vehicle.

[0035] In this case, the brake caliper 16 is connected to the brake carrier 18 via a linear guide 20 and is mounted displaceably in the axial direction relative to the brake carrier 18 via said guide and thus in a floating manner.

[0036] The brake caliper 16 surrounds a brake rotor (not shown), in particular a brake disk, which can be clamped in the axial direction by a brake pad set 22 .

[0037] The brake pad set 22 includes an inner brake pad 24 and an outer brake pad 26 , wherein each brake pad 24 , 26 has a backing plate 28 and a brake lining 30 , 32 mounted on the backing plate 28 and contacting the brake rotor when the vehicle brake 10 is actuated.

[0038] Here, the back plate 28 corresponds to a commonly used back plate 28 , so that the brake pad set 22 can be installed in any vehicle brake 10 without the need to replace the vehicle brake 10 .

[0039] In order to fix the brake linings 30 , 32 on the back plate 28 , the brake linings 30 , 32 can each have one or more extensions on their side facing the back plate 28 , wherein these extensions engage in recesses in the back plate 28 .

[0040] Alternatively, the back plate 28 can also have an extension on its side facing the brake linings 30 , 32 , which engages in a recess in the brake linings 30 , 32 .

[0041] The brake pad 24 located on the inner side in the axial direction is mounted on the brake bracket 18 so as to be movable in the axial direction.

[0042] In contrast, the brake pad 26 located on the outside in the axial direction abuts against at least one abutment extension 34 which is an integral part of the brake caliper 16. Typically, the outer brake pad 26 abuts against two laterally spaced abutment extensions 34, such as Figure 1 shown.

[0043] For the lateral mounting of the brake pads and to provide for their axial mobility, the brake carrier 18 has a U-shaped receptacle for each brake pad and, on both side walls of the U, recesses into which laterally projecting fingers provided on the back plate project in each case.

[0044] When the vehicle brake 10 is activated, the brake pad 24 located on the inside along the rotation axis of the actuator unit 12 defining the axial direction is actively subjected to the force applied by the actuator unit 12 , in particular by the brake cylinder.

[0045] Preferably, the axis of rotation of the actuator unit 12 also corresponds to the cylinder axis of the brake housing 14 and the brake rotor rotation axis of the brake rotor.

[0046] The axially movable brake caliper 16 ensures that the force likewise acts on the brake pads 26 which are located laterally in the axial direction. In this case, the force is distributed approximately uniformly in terms of size between the inner brake pads 24 and the outer brake pads 26. As a result of the contact pressure provided, it is thus possible to ensure a frictional engagement of both brake pads 24, 26 of the brake pad set 22 with the brake rotor for decelerating or stopping the vehicle.

[0047] It can be seen in Figure 5 that the actuator unit 12, in particular the brake cylinder, engages centrally on the inner brake pads 24.

[0048] On the other hand, Figure 1 The abutment extensions 34 are shown on which the back plate 28 of the outer brake pads 26 is supported.

[0049] Figure 5 and Figure 6 It can be seen in comparison that, when viewed in the axial direction, the rear-side contact surface 36 of the inner brake pads 24 which is in contact with the actuator unit 12 is located between the rear-side contact surfaces 36 of the back plate 28 of the outer brake pads 26 which are in contact with the abutment extensions 34.

[0050] In order to ensure a uniform application of force on the respective brake linings 30, 32, the inner brake linings 30 and the outer brake linings 32 differ in terms of size and preferably also in terms of geometry in the plan view.

[0051] That is to say, for example, the inner brake pads 24 have square or circular brake linings 30, while the outer brake pads 26 have arc-shaped or oblong brake linings 32.

[0052] Ideally, the size and / or the geometry of the brake linings 30, 32 in the plan view is chosen such that the rear-side contact surface 36 does not protrude beyond the respective brake lining 30, 32.

[0053] However, the brake linings 30, 32 should also not be significantly larger than the rear-side contact surface 36, so that an inhomogeneous application of force to the respective brake linings 30, 32 can be avoided.

[0054] The area of the brake linings 30 of the inner brake pads 24 is thus preferably smaller than the area of the brake linings 32 of the outer brake pads 26 in the plan view, since the rear-side contact surface 36 of the inner brake pads 24 is limited to the actuator unit 12, in particular the brake cylinder. In contrast, as described above, the rear-side contact surface 36 of the outer brake pads 26 corresponds to the two abutment extensions 34.

[0055] Due to the use of the inner brake pad 30 having a smaller area in the plan view, a potentially greater wear is avoided, which avoids a residual brake torque and the resulting troublesome noise.

[0056] In this case, the brake pad 30 of the inner brake pad 24 has a smaller area than the brake pad 32 of the outer brake pad 26, in particular at least 10% smaller.

[0057] Ideally, the area of the inner brake pad 30 is 20% to 300% smaller than the area of the outer brake pad 32. In other words, the area of the outer brake pad 32 is at least 10%, preferably 20% to 300% larger than the area of the inner brake pad 30. Thus, the difference between the inner brake pad 30 and the outer brake pad 32 is outside the manufacturing tolerances.

[0058] In order to continue to ensure uniform wear of both brake pads 30, 32, the wear volume of the inner brake pad 24 and the wear volume of the outer brake pad 26 differ by less than 10%.

[0059] In order to ensure that the wear volume of the inner brake pad 30 does not differ too much from the wear volume of the outer brake pad 32, the brake pad 30 of the inner brake pad 24 is thicker than the brake pad 32 of the outer brake pad 26. That is, the smaller the area of the brake pad 30, the greater the thickness of the brake pad 30.

[0060] Thus, since the wear volumes of the inner brake pad 24 and the outer brake pad 26 hardly differ, it is possible in each case to replace the entire brake pad set 22 without wasting material.

[0061] In addition, the back plate 28 of the inner brake pad 24 can be thicker than the back plate 28 of the outer brake pad 26. Alternatively, the two back plates 28 of the brake pad set 22 are of the same thickness.

[0062] In principle, if a thicker back plate 28 is used, the brake pads 30, 32 can be pressed more firmly against the brake rotor. Thus, a thicker back plate 28 can exert a more uniform braking force. Since the inner brake pad 30 has a smaller area than the outer brake pad 32, it can be advantageous if the back plate 28 of the inner brake pad 24 is slightly thicker.

[0063] In order to better accommodate the rear-side contact surface 36 of the abutment extension 34 on the outer brake pad 26, the brake pad 32 of the outer brake pad 26 can be divided into two parts. In this case, the gap between the split brake pads 32 is located at the level of the gap between the two abutment extensions 34 (see Figure 6 ).

[0064] The two brake pads 30, 32 not only differ in their size and geometry in plan view, but also in their material. That is to say, the inner brake pad 30 can be manufactured from a different material than the outer brake pad 32. Here, the difference between the materials lies in the friction coefficient.

[0065] Thus, for example, a material with a higher friction coefficient and a higher tendency to wear can be selected for the outer brake pad 32 in order to meet the respective requirements for the brake pad 32.

[0066] Due to the different size and shape of the brake pads 30, 32, the brake pads 30, 32 are also located at different radial heights relative to the brake rotor.

[0067] As an alternative to the preferably square or circular shape in plan view of the inner brake pad 30, it can also have an approximately square oblong or arcuate shape. In this case, the oblong shape of the inner brake pad 30 preferably has a ratio of the width b to the height h of less than or equal to 3:2, in particular less than or equal to 4:3, particularly preferably less than or equal to 5:4. If the inner brake pad 30 has an arcuate shape, the width at the radial height of the central axis A of the brake cylinder on which the inner brake pad 30 lies, which also forms the central axis of the driven spindle in the case of an electromechanical brake, is considered to be the width (see Figure 5 ).

[0068] As an alternative, it can be the case here, for example, for the brake pad 30 of the inner brake shoe 24, that the ratio of the height h to the width b of the inner brake pad 30 should be between 0.6 and 1.1.

[0069] It follows from this that the height of the inner brake pad 30 should be at least not significantly smaller than the width of the inner brake pad 30, and thus the inner brake pad 30 has a slightly square or long oblong shape in the view towards the friction surface.

Claims

1. A brake pad set (22) for a disc brake, the brake pad set (22) comprising an inner brake pad (24) and an outer brake pad (26), wherein, Each brake pad (24, 26) has a back plate (28) and a brake lining (30, 32) which is mounted on the back plate (28) and which is in contact with a brake rotor during operation, characterized in that the brake lining (30) of the inner brake pad (24) and the brake lining (32) of the outer brake pad (26) differ in size and preferably also in geometry in a plan view, wherein the wear volume of the inner brake pad (24) and the wear volume of the outer brake pad (26) differ by less than 10%.

2. The brake pad set (22) according to claim 1, characterized in that The brake lining (30) of the inner brake pad (24) is designed square or circular in a plan view and / or the brake lining (32) of the outer brake pad (26) has an arcuate shape or an oblong shape.

3. The brake pad set (22) according to claim 1 or 2, characterized in that The brake lining (32) of the outer brake pad (26) has a larger area in a plan view than the brake lining (30) of the inner brake pad (24), in particular at least 10% larger, further in particular 20% to 300% larger.

4. The brake pad set (22) according to claim 3, characterized in that The brake lining (30) of the inner brake pad (24) is thicker than the brake lining (32) of the outer brake pad (26).

5. The brake pad set (22) according to any one of the preceding claims, characterized in that The back plate (28) of the inner brake pad (24) is thicker than the back plate (28) of the outer brake pad (26) or the back plate (28) of the inner brake pad (24) is the same thickness as the back plate (28) of the outer brake pad (26).

6. The brake pad set (22) according to any one of the preceding claims, characterized in that The brake lining (32) of the outer brake pad (26) is divided into two parts.

7. The brake pad set (22) according to any one of the preceding claims, characterized in that The brake lining (32) of the outer brake pad (26) and the brake lining (30) of the inner brake pad (24) are made of different materials.

8. The brake pad set (22) according to any one of the preceding claims, characterized in that The ratio of the height (h) to the width (b) of the brake lining (30) of the inner brake pad (24) is between 0.6 and 1.

1.

9. The brake pad set (22) according to any one of the preceding claims, characterized in that The brake lining (30) of the inner brake pad (24) and the brake lining (32) of the outer brake pad (26) are arranged at different radial heights relative to the brake rotor.

10. A vehicle brake (10), in particular an electromechanical vehicle brake (10), comprising a brake caliper (16), a brake carrier (18), an actuator unit (12) and a brake pad set (22) according to any one of the preceding claims, a brake rotor extending into the brake carrier (18).

11. The vehicle brake (10) according to claim 10, characterized in that The actuator unit (12) is engaged centrally on the inner brake pad (24) and the brake caliper (16) has an abutment extension (34) on which the back plate (28) of the outer brake pad (26) is supported by means of a rear contact surface when the vehicle brake is activated, wherein the inner brake pad (24) has a rear contact surface which is in contact with the actuator unit (12) and which, when viewed in the axial direction, is located between the rear contact surfaces of the back plate (28) of the outer brake pad (26) which are in contact with the abutment extension (34).

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