Method for setting clearance of disc brake, brake pad and service brake

Abstract

The invention relates to a method for setting a clearance of a disc brake, a brake pad and a service brake. The disc brake (10) comprises a brake caliper (12), a brake piston, a brake disc (16), a brake pad, at least one drive unit (30), which is assigned to the brake pad and by means of which a restoring force can be applied to the assigned brake pad; and at least one sensor, which is assigned to at least one brake pad coupled to the drive unit (30), in which a physical value of the brake pad is determined, the physical value is compared with an assigned predetermined limit value or a predetermined limit value range, and, if necessary, the at least one brake pad is assigned to the at least one brake pad coupled to the drive unit (30). The brake pads are adjusted by an associated drive unit (30).

Description

Technical Field

[0001] The invention relates to a method for setting the clearance of a disc brake, a brake pad and a service brake for a motor vehicle. Background Art

[0002] In the case of disc brakes, the brake pad is usually reset after a braking operation. This is achieved, for example, by an elastic brake piston seal, which is deformed during the braking operation and returns to its original shape after the brake is released. Accompanying the actuation of the brake piston, this also resets the brake pad assigned to the brake piston. The brake pad is thereby separated from the brake disc and a so-called gap is created between the brake pad and the brake disc, thereby ensuring that there is no unnecessary fuel consumption or brake wear caused by the drag of the brake pad. Also common is the reset by an elastic reset element, for example a reset arm integrated into the bearing clamp.

[0003] The setting of the clearance of the outer brake pad of a sliding caliper disc brake is usually achieved by a spring. In this case, the restoring force on the outside must be greater than the restoring force on the inside, because the outer brake pad must overcome the friction in the housing guide and must additionally move the entire brake caliper.

[0004] A disadvantage of the known system is that conventional return mechanisms using pad return springs achieve a relatively low restoring force. As a result, these return mechanisms cannot reliably return the brake caliper during the service life of the disc brake. In particular, when there is contamination and the associated increased friction between the pad and the pad guide, the restoring force may no longer be sufficient. With increasing contamination, the spring force may no longer be sufficient to allow a complete return of the pad.

[0005] Furthermore, if the disc deflects when the motor vehicle is turning, the brake caliper is displaced relative to the brake carrier. This cannot usually be compensated by the pad return spring.

[0006] Another disadvantage is that the clearance changes over time due to wear on the brake pads and the brake disc. For example, the clearance is also subject to constant changes during operation of a motor vehicle, in particular due to temperature changes of the brakes.

[0007] The individual brakes of a motor vehicle may also have different clearances. Therefore, the individual brakes may have different response times and possibly also different braking forces. Summary of the invention

[0008] On this basis, the object of the present invention is to provide a method by which the setting of the clearance of a disc brake can be achieved in a reliable and accurate manner. In addition, a corresponding brake pad is to be provided which allows a reliable and accurate setting.

[0009] According to the invention, the object is achieved by a method for setting the clearance of a disc brake of a motor vehicle, the disc brake comprising: a brake caliper; a brake piston; a brake disc; a brake pad; at least one drive unit, which is assigned to the brake pad and by which a restoring force can be applied to the assigned brake pad; and at least one sensor, which is assigned to the at least one brake pad coupled to the drive unit, characterized by the following method steps:

[0010] a) determining at least one physical value of the brake pad by means of the at least one sensor assigned to the brake pad;

[0011] b) comparing the determined physical value with an assigned predetermined limit value or a predetermined limit value range; and

[0012] c) when at least one determined physical value of the brake pad reaches or falls below at least one assigned limit value or is outside the limit value range, the drive unit assigned to the brake pad adjusts the brake pad according to the determined physical value and adjusts the clearance to another value different from zero.

[0013] In this case, the disc brakes are the vehicle's service brakes.

[0014] The basic idea of ​​the invention is to determine by means of physical values ​​whether the brake pad is still in contact with the brake disc and / or what the clearance is, ie what the distance between the brake pad and the brake disc is.

[0015] "Determining" at least one physical value by a sensor means estimating or sensing the physical value.

[0016] Based on this, it can be determined by comparing the at least one physical value with a predetermined limit value or a predetermined limit value range whether further adjustment of the brake pad is required or whether the brake pad is already in a position where a desired clearance exists.

[0017] Based on said physical values ​​it is thus possible to determine the positioning of the brake pad and thus also the clearance and, if necessary, to perform an active adjustment of the brake pad based on this basis.

[0018] In this case, the predetermined limit value or the predetermined limit value range is defined in such a way that there is no contact between the brake pad and the brake disc, or the gap is as large as is necessary to prevent an undesired contact between the brake pad and the brake disc in any driving situation and is small enough to achieve a fast response behavior of the brake when the brake is actuated.

[0019] The terms "limit value" and "limit value range" should also be understood as being synonymous with target value and target value range.

[0020] One aspect provides that steps a) to c) are continuously performed by the electronic control device as long as the determined physical value of the brake pad reaches or falls below a predetermined limit value or is outside a limit value range or has reached a specified position at which a predetermined play exists.

[0021] This allows the brake pads to be set to the desired position with specified precision and accuracy.

[0022] Furthermore, the adjustment of the brake pad in step c) by the drive unit assigned to the brake pad can be effected by the drive unit being activated as a function of the determined physical value for a period of time derived from the determined physical value.

[0023] This allows a particularly fast and easy adjustment of the brake pad. In addition, this also makes it possible to perform a relatively precise setting of the brake pad, since the adjustment via the drive unit depends on the determined physical value.

[0024] Furthermore, the physical value of the brake pad may be the pressure and / or the clearance that the brake pad applies to the brake disc.

[0025] If the physical value of the brake pad is the pressure that the brake pad applies to the brake disc, this is a particularly simple way of determining whether the brake pad is still in contact with the brake disc and therefore at least a residual friction torque is acting on the brake disc via the brake pad, or whether the brake disc is free running and there is no contact between brake pad and brake disc.

[0026] If the physical value of the brake pad is the play, it is possible to determine from this not only whether there is contact between the brake pad and the brake disk, but also how much play is already present.

[0027] If the physical value is the travel distance of the brake pad, it is possible to determine not only whether there is contact between the brake pad and the brake disc, but also how much gap exists, or whether the brake pad has reached the desired specified position, or how far the axial distance of the brake pad is from the desired specified position.

[0028] It can be determined from this whether the play is too small, so that the brake pad drags on the brake disc despite the play, for example during dynamic travel, or whether the play is too large, which would impair the response behavior of the brake.

[0029] If a physical value of the brake pad is related both to the pressure which the brake pad applies to the brake disc and to the clearance or the axial brake pad position, a particularly precise setting of the clearance can be achieved on the basis of this.

[0030] There may also be a plurality of sensors arranged on the brake pad and a plurality of drive units coupled to the brake pad. In addition, each drive unit may be assigned to a sensor, in which case, in step c), the adjustment of the brake pad may be individually realized by each drive unit based on the respective assigned sensor.

[0031] Thus, for example, the front side of the brake pad can be adjusted independently of the rear side. This is particularly advantageous if there is uneven wear on the brake pad, for example resulting in one area of ​​the brake pad still being in contact with the brake disc while a gap has been achieved between the brake disc and another area of ​​the brake pad.

[0032] Steps a) to c) may be automatically performed after the service brake is actuated.

[0033] This has the advantage that the respective brake pad is realigned each time relative to the brake disc, so that the required clearance is always present and any wear on the brake pad and brake disc is always taken into account.

[0034] The objects stated at the outset are further achieved by a brake pad comprising: a pad carrier plate; a friction material layer arranged on the pad carrier plate; and at least one sensor assigned to the brake pad, the at least one sensor being a pressure sensor and / or a distance sensor operating in a contactless manner, and the sensor being at least partially arranged between the pad carrier plate and the friction material layer.

[0035] The sensor is thus integrated in the brake pad itself. This has the advantage that no additional space needs to be provided for the sensor.

[0036] Furthermore, integrating the sensor into the brake pad makes it particularly easy to sense whether the brake pad is still applying pressure to the brake disc and / or whether the brake pad has a clearance relative to the brake disc and how large this clearance is.

[0037] The brake pad may comprise at least two sensors, wherein one sensor is arranged in the region of a front side of the brake pad and another sensor is arranged in the region of a rear side of the brake pad.

[0038] In this way, by means of sensors arranged on different areas of the brake pad, it is possible to determine individually whether a corresponding area of ​​the brake pad is in contact with the brake disc, or how large the gap is between an area of ​​the brake pad and the brake disc. This can also be used to determine whether there is uniform wear on the brake pad.

[0039] Furthermore, even if one sensor fails, the second sensor that is still functioning can continue to detect data.

[0040] Additionally or alternatively, the brake pad can comprise at least two sensors, wherein one sensor is arranged in a radially inner region relative to the brake disk and the other sensor is arranged in a radially outer region.

[0041] The resulting advantages are evident from the above explanation, and these advantages are intensified if sensors are provided on the front side, on the rear side, in the radially inner region and in the radially outer region of the brake pad.

[0042] Furthermore, the brake pad can have at least one coupling point, at which the brake pad can be coupled to at least one drive unit, and a restoring force can be applied to the brake pad by the at least one drive unit in the region of the at least one coupling point.

[0043] This allows a particularly simple adjustment of the brake pad.

[0044] The at least one coupling point can also be arranged in the region of the at least one sensor.

[0045] This allows firstly to sense a corresponding physical value by means of a sensor and, in a next step, to directly influence this physical value by adjusting the brake pad via a drive unit arranged at the respective coupling point.

[0046] In this way, each region of the brake pad in which the coupling point is arranged in the region of the sensor can be precisely set.

[0047] At least one drive unit can be an electromagnetic drive unit having at least one coil core, through which a magnetic force can be applied to the brake pad by means of a coil. In this case, the coil core can form a connection point or can also be fastened to a connection point.

[0048] The electromagnetic drive unit requires very little space. Furthermore, despite its compact design, it allows high forces to be exerted on the brake pad if necessary.

[0049] The at least one sensor may be a piezoelectric sensor.

[0050] Piezoelectric sensors are versatile and particularly robust. They are particularly suitable as pressure sensors, but can also be used as contactless distance sensors, in particular in the form of ultrasonic sensors.

[0051] The sensing of the position of the brake pad and thus the determination of the travel distance or clearance can also be achieved via one or more sensors which are not integrated in the brake pad but which can feed physical values ​​as input signals into the electronic controller.

[0052] The object stated at the outset is further achieved by a service brake for a motor vehicle, which comprises a brake pad according to the invention and comprises an electronic control device for carrying out the method according to the invention.

[0053] From the above paragraphs, the advantages obtained are obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The present invention is described below based on the embodiments shown in the accompanying drawings. In these drawings:

[0055] Figure 1 shows a perspective view of a disc brake according to a first alternative for carrying out the method according to the invention;

[0056] Figure 2 Shows Figure 1 A front view of a disc brake;

[0057] Figure 3 Shows Figure 1 A cross-sectional view of a disc brake along plane III-III;

[0058] Figure 4 A schematic representation of a disc brake according to a first alternative is shown in a top view;

[0059] Figure 5 A schematic representation of a brake pad according to the invention according to a first option is shown in front view;

[0060] Figure 6 Shown from Figure 4 Rear view of the brake pad;

[0061] Figure 7 shows a perspective view of a disc brake according to a second alternative for carrying out the method according to the invention;

[0062] Figure 8 Shows Figure 7 A front view of a disc brake;

[0063] Fig. 9 Shows Figure 7 The disc brake along Figure 8 A cross-sectional view of the plane IX-IX in FIG.

[0064] Fig.10 A schematic representation of a disc brake according to a second alternative is shown in a top view;

[0065] Fig.11 a schematic representation of a brake pad according to the invention according to a second option is shown in front view; and

[0066] Fig.12 A schematic representation of a brake pad according to the invention according to a third option is shown in front view. DETAILED DESCRIPTION

[0067] Figures 1 to 4 A disc brake 10 for a service brake of a motor vehicle is shown according to a first alternative.

[0068] The disc brake 10 comprises a brake caliper 12 (embodied here by way of example as a sliding caliper) having a recess 14 in which a brake disc 16 and a brake pad 18 are arranged (the brake disc 16 is only Figure 3 and Figure 4 ), the brake pads are arranged on both sides of the brake disc 16.

[0069] The brake pad 18 can be pressed against the brake disc 16 by a brake piston 20 (the brake piston can be linearly moved along the axial direction A), so that a braking force can be provided.

[0070] Furthermore, a brake carrier 22 is provided, on which the brake caliper 12 is movably mounted. Furthermore, the brake carrier 22 serves to connect the disc brake 10 to the vehicle.

[0071] The brake support 22 includes: a web 24 that extends laterally along the brake caliper 12 in the axial direction A; and an outer structure 26 that extends along the front side of the brake caliper 12 and connects the ends of the web 24 together (see Figure 2 ).

[0072] A guide groove 28 , along which the brake pad 18 is guided in the axial direction A, is provided on the web 24 on the side facing the brake caliper.

[0073] Furthermore, a drive unit 30 is assigned to each brake pad 18 , which is coupled to the respective brake pad 18 . Figures 1 to 4 The drive unit 30 shown in FIG. 1 is implemented as an electromagnetic drive unit, and can apply a magnetic force to the assigned brake pad 18 .

[0074] In this case, the drive units 30 serve to adjust the brake pads 18 in the axial direction A, thereby in particular enabling a restoring force to be applied to the assigned brake pad 18 by the respective drive unit 30. The drive units 30 are not used to actuate the service brakes for braking the vehicle.

[0075] Alternatively, it is also conceivable to assign the drive unit 30 to only one of the brake pads 18 .

[0076] The drive unit 30 comprises a coil core 32 which is coupled to the associated brake pad 18 and a coil 34 which is fixed to a web 36 which extends from the outer structure 26 of the brake carrier 22 and is arranged in a recess 38 of the brake caliper 12 which is formed by two fingers 40 of the brake caliper 12 .

[0077] In the following, reference will be made to Figures 4 to 6 The structure of the brake pad 18 will be described in more detail.

[0078] Each brake pad 18 has a pad carrier plate 42 on which a layer of friction material 44 is disposed.

[0079] Furthermore, at least one sensor 46 is assigned to each brake pad 18, which is a pressure sensor 48 and / or a contactlessly operated distance sensor 50. In the following, all variants of sensor 46 are therefore indicated by using reference numerals 46, 48, 50.

[0080] Furthermore, the sensor 46 may be implemented as a piezoelectric sensor.

[0081] The sensor 46 allows the gap L to be detected (see Figure 4 ). If the sensor 46 is a distance sensor 50 operating in a contactless manner, the gap L can be measured.

[0082] In this case, the at least one sensor 46 is arranged between the pad carrier plate 42 and the friction material layer 44 of the brake pad 18 (see in detail Figure 5 ).

[0083] As specifically from Figure 5 and Figure 6 As can be seen in FIG. 1 , the brake pad 18 can also have a plurality of sensors 46 , 48 , 50 .

[0084] On both brake pads 18 there is therefore in each case a sensor 46 , 48 , 50 which is arranged in the region of the front side 52 and a further sensor 46 , 48 , 50 which is arranged in the region of the rear side 54 .

[0085] Furthermore, there are sensors 46 , 48 , 50 which are arranged in a radially inner region 56 relative to the brake disk 16 and there are also sensors 46 , 48 , 50 which are arranged in a radially outer region 58 .

[0086] Alternatively, more or less than four sensors may be provided in the brake pad.

[0087] Furthermore, a coupling point 60 is provided on the brake pad 18, at which the drive unit 30 can be coupled to the brake pad 18 so that a restoring force can be applied to the brake pad 18 (see in detail Figure 4 ).

[0088] Furthermore, an electronic control device 62 is provided, which is electrically coupled to the sensors 46 , 48 , 50 and the drive unit 30 .

[0089] Figures 7 to 11 A disc brake 10 according to a second alternative is shown.

[0090] and Figures 1 to 6 In contrast to the disc brake 10 shown, the disc brake 10 according to the second alternative has two drive units 30 per brake pad, which are provided in the region of the web 24 of the brake carrier 22 .

[0091] In this case, the coils 34 are each arranged on the brake carrier 22 , while the coil cores 32 are arranged in the region of the front side 52 and the rear side 54 of the brake pad 18 .

[0092] Therefore, according to the second option, Fig.11 The brake pad 18 shown in FIG. 1 also has two connection points 60 , to which the coil core 32 is joined.

[0093] Furthermore, the connection points 60 are arranged in the region of the sensors 46 , 48 , 50 , so that in each case there is a drive unit 30 assigned to the sensor 46 , 48 , 50 in the region of the front side 52 and the rear side 54 .

[0094] Fig.12 A brake pad 18 according to a third option is shown. In this option, the brake pad 18 has four connection points 60, so that there is a drive unit assigned to each sensor 46, 48, 50.

[0095] Next, a method for setting the clearance L of the disc brake 10 will be described. This method may be performed on two brake pads 18 or may be performed on only a single brake pad 18 .

[0096] In a first step of the method, a physical value of the respective brake pad 18 is determined. This is accomplished by means of sensors 46 , 48 , 50 assigned to the brake pad 18 .

[0097] In this case, the physical value is, for example, the pressure applied by the brake pad 18 to the brake disc 16. The sensor 46 is therefore a pressure sensor 48 (for example a piezoelectric sensor).

[0098] Additionally or alternatively, the physical value may also be the gap L between the brake pad 18 and the brake disk 16 , so that the sensor 46 is additionally or alternatively embodied as a contactlessly operated distance sensor 50 .

[0099] In a next step, the determined physical value is compared with an assigned predetermined limit value or a predetermined limit value range.

[0100] If the physical value is the pressure exerted by the brake pad 18 on the brake disc 16, it is recommended to select the predetermined limit value or the limit value range in such a way that no residual torque (for example due to the drag of the brake pad 18) acts on the brake disc 16, or to select the predetermined limit value or the limit value range in such a way that the braking torque is small enough to be negligible.

[0101] If the physical value additionally or alternatively corresponds to a gap L between the brake pad 18 and the brake disc 16 , the predetermined limit value or the predetermined limit value range can be selected in such a way that, despite this gap, an optimal braking response behavior can be achieved and there is no contact between the brake disc 16 and the brake pad 18 even during dynamic travel.

[0102] If a plurality of sensors 46 , 48 , 50 are provided, each physical value determined by a sensor 46 , 48 , 50 is compared with a predetermined limit value or a predetermined limit value range.

[0103] If the determined physical value of a brake pad 18 reaches or exceeds an assigned limit value, or if the determined physical value is outside a predetermined limit value range, the corresponding brake pad 18 is adjusted by the at least one drive unit 30 .

[0104] The adjustment of the drive unit 30 is performed according to the determined physical value, wherein the gap L is set to at least one other value than zero.

[0105] As long as the determined physical value of the brake pad 18 reaches or falls below a predetermined limit value or is outside a predetermined limit value range, or until the brake pad 18 has reached a predetermined designated position where a predetermined gap L exists, the electronic control unit 62 continuously implements the determination of the physical value and the comparison of the determined physical value with the assigned limit value or limit value range.

[0106] Alternatively, the adjustment of the brake pad 18 by the assigned drive unit 30 can also be realized by the drive unit 30 being activated as a function of the determined physical value for a period of time derived from the determined physical value.

[0107] If the deviation in the comparison of the physical value with the assigned predetermined limit value or predetermined limit value range is particularly large, the drive unit 30 is activated for a longer period of time than if only a small deviation exists.

[0108] In the case of a disk brake 10 according to the second alternative, in step c), the adjustment of the brake pad 18 can be effected individually by each drive unit 30 on the basis of the physical values ​​determined by the respective assigned sensor 46 , 48 , 50 .

[0109] Thus, for example, if only one of the determined physical values ​​of brake pad 18 reaches or exceeds a predetermined limit value or is outside a limit value range, brake pad 18 is also regulated only by drive unit 30 assigned to the respective sensor 46 , 48 , 50 .

[0110] The method may be performed automatically after service brake actuation.

[0111] Alternatively, the method can also be carried out only after a service brake actuation in which a certain threshold value suitable for characterizing the service brake intensity has been exceeded.

Claims

1. A method for setting the clearance of a disc brake (10) of a motor vehicle, the disc brake comprising: Brake caliper (12); Brake piston (20); Brake disc (16); Brake pad (18); At least one drive unit (30) which is assigned to a brake pad (18) and by which a restoring force can be applied to the assigned brake pad (18); and at least one sensor (46, 48, 50) which is assigned to the at least one brake pad (18) coupled to the drive unit (30), characterized in that the following procedure step: a) determining at least one physical value of the brake pad (18) by means of the at least one sensor (46, 48, 50) assigned to the brake pad (18); b) comparing the determined physical value with an assigned predetermined limit value or a predetermined limit value range; and c) when at least one determined physical value of the brake pad (18) reaches or falls below at least one assigned limit value or is outside the limit value range, the drive unit (30) assigned to the brake pad (18) adjusts the brake pad (18) according to the determined physical value and adjusts the clearance to another value different from zero.

2. The method according to claim 1, characterized in that As long as the determined physical value of the brake pad (18) reaches or falls below the predetermined limit value or is outside the limit value range or has reached a specified position where a predetermined clearance exists, steps a) to c) are continuously performed by the electronic control device (62).

3. The method according to claim 1, characterized in that In step c), the brake pad (18) is adjusted by the drive unit (30) assigned to the brake pad (18) by the drive unit (30) being activated in dependence on the determined physical value for a period of time derived from the determined physical value.

4. The method according to any one of the preceding claims, characterized in that The physical value of the brake pad (18) is the pressure applied by the brake pad (18) to the brake disc (16) and / or the clearance and / or travel distance of the brake pad (18).

5. The method according to any one of the preceding claims, characterized in that There are a plurality of sensors (46, 48, 50) arranged on the brake pad (18) and a plurality of drive units (30) connected to the brake pad (18), and each drive unit (30) is assigned to a sensor (46, 48, 50), in which case, in step c), the adjustment of the brake pad (18) is individually realized by each drive unit (30) based on the corresponding assigned sensor (46, 48, 50).

6. The method according to any one of the preceding claims, characterized in that Steps a) to c) are automatically carried out after the service brake is actuated.

7. A brake pad, comprising: Liner bearing plate; A friction material layer (44) disposed on the pad bearing plate; and at least one sensor (46, 48, 50) assigned to the brake pad (18), the at least one sensor (46, 48, 50) being a pressure sensor (48) and / or a distance sensor (50) operating contactlessly and being arranged at least partially between the pad carrier plate and the friction material layer (44).

8. The brake pad according to claim 7, characterized in that The brake pad (18) comprises at least two sensors (46, 48, 50), wherein one sensor (46, 48, 50) is arranged in the region of a front side (52) of the brake pad (18) and the other sensor (46, 48, 50) is arranged in the region of a rear side (54) of the brake pad (18).

9. The brake pad according to claim 7 or 8, characterized in that: The brake pad (18) comprises at least two sensors (46, 48, 50), wherein one sensor (46, 48, 50) is arranged in a radially inner region (56) relative to the brake disk (16) and the other sensor (46, 48, 50) is arranged in a radially outer region (58).

10. The brake pad according to any one of claims 7 to 9, characterized in that The brake pad (18) has at least one connection point (60) at which the brake pad (18) can be connected to at least one drive unit (30), and a restoring force can be applied to the brake pad (18) by the at least one drive unit (30) in the region of the at least one connection point (60).

11. The brake pad according to claim 10, characterized in that The at least one connection point (60) is arranged in the region of the at least one sensor (46, 48, 50).

12. The brake pad according to claim 10 or 11, characterized in that The at least one drive unit (30) is an electromagnetic drive unit having at least one coil core (32) via which a magnetic force can be applied to the brake pad (18) by means of a coil (34).

13. The brake pad according to any one of claims 7 to 12, characterized in that The at least one sensor (46, 48, 50) is a piezoelectric sensor.

14. A service brake for a motor vehicle, comprising a brake pad (18) according to any one of claims 7 to 13 and comprising an electronic control device (62) for performing a method according to any one of claims 1 to 6.

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