WO2020057911A1

WO2020057911A1 - Measuring system that can be retrofitted for determining the wear of a brake lining of a friction brake

Info

Publication number: WO2020057911A1
Application number: PCT/EP2019/072811
Authority: WO
Inventors: Alexander Fuchs; Alexander Werth; Michael Blessing
Original assignee: Knorr-Bremse Systeme für Nutzfahrzeuge GmbH
Priority date: 2018-09-18
Filing date: 2019-08-27
Publication date: 2020-03-26
Also published as: DE102018122882A1; DE102018122882B4

Abstract

The invention relates to a measuring system that can be retrofitted for determining the wear of a brake lining (2) of a friction brake, having a sensor device (10) for detecting a position of a brake lining carrier (3) relative to another component of the friction brake. The sensor device (10) is designed to detect at least three different positions of the brake lining carrier (3) so as to be distinguishable.

Description

DESCRIPTION

Retrofittable measuring system for determining wear of a

Brake pads of a friction brake

The invention relates to a retrofittable measuring system for determining wear of a brake lining of a friction brake.

A distinction is made between discrete and continuously operating systems in measuring systems for determining wear of a brake lining. In the case of discretely operating systems, as a rule only a final wear value, that is to say a maximum permissible wear of the brake lining, is recorded and output. Such a signal is called

Understand the warning signal for the driver and have the pads replaced as soon as possible. This prevents trips with the brakes no longer working reliably.

Continuously operating measuring systems also continuously or quasi-continuously output a current wear value of a brake pad, the one

The degree of wear of the brake pad, for example, indicates a percentage. The term continuous is an indication at certain time intervals or at certain driving situations, for. B. at every engine start to understand. An output in a plurality of levels, for example in certain percentage steps of the

Degree of wear, also falls under a continuous issue of a

Wear value.

Continuous measuring systems not only enable the detection of the

Wear value, but allow a preventive or predictive

Maintenance control that advantageously enables efficient use of parts, particularly in the commercial vehicle sector. Costs for visits to the workshop are also saved and downtime is reduced. Furthermore, malfunctions on one

Brake system, for example, to uneven wear

Lead brake pads, recognize with continuously working measuring systems.

Continuous measuring systems are known in the prior art as integrated systems in vehicle brakes of drive vehicles. For trailers or semi-trailers As a rule, discretely operating measuring systems are used, which can also be used as

Retrofit solutions are available. Such a retrofit solution is e.g. in the

Document DE 10 2008 026 104 B4 described.

Starting from this known prior art, it is an object of the present invention to provide a retrofittable measuring system of the type mentioned at the outset, which can not only detect an end-of-wear condition, but also provides additional information on the wear of the brake linings.

This task is solved by a measuring system with the characteristics of the

independent claim. Advantageous refinements and developments are the subject of the dependent claims.

A measuring system according to the invention for determining wear of a

Brake lining of a friction brake has a sensor device for detecting a position of a brake lining carrier relative to another component of the

Friction brake on. It is characterized in that the sensor device is designed to distinguishably detect at least three and preferably a plurality of different positions of the brake lining carrier.

With such a sensor device, the measuring system is no longer able to detect only one end point of wear, but to differentiate between several wear states. A continuous position value for the

Brake pad carrier related to the other components of the friction brake detected. The wear on the brake pads can be tracked continuously and an exchange can be planned in advance, which minimizes downtimes and workshop times. The continuous position value can be recorded and processed analog or digital with a suitable resolution.

In the case of a disc brake, the further component mentioned, relative to which the position of the brake pad carrier is detected, is e.g. a caliper. The position value for the brake pad carrier is then a measure of the cumulative wear of both

Brake pads. In an advantageous embodiment of the measuring system, the sensor device has a linearly displaceable sensing element, the displacement of which is detected and which bears against the brake lining carrier. The feeler element is preferably spring-loaded in order to bear against the brake lining carrier with a pressing force. The sensor device can thus sense the position of the brake pad carrier that changes as a result of wear of the brake pads. The feeler element can be straight or single or multiple angled or curved in order to extend from the position of the sensor device to the brake pad carrier.

As an alternative to such a push-button element pressing against the brake pad carrier, a free end of the push-button element can also be connected to the brake pad carrier in a tensile manner, e.g. through appropriately positive contours. In this case, the feeler element can also include a pull rope that is tensioned under spring force.

In an advantageous embodiment of the measuring system, the sensor device itself is fastened to the further component of the friction brake via a holding bracket. By using the retaining bracket, an attachment option in the area of the sensor device that is already present can be selected, for example an existing threaded hole or the like. The holding bracket allows a corresponding flexibility for positioning the sensor device and for using existing fastening options.

In a further advantageous embodiment of the measuring system, the

Sensor device on a sensor for detecting a position of the linearly displaceable element, which is coupled to the probe element or is formed by the probe element. The sensor can work potentiometrically, capacitively, inductively, optically or via ultrasound.

In a further advantageous embodiment of the measuring system

Sensor device designed to detect a position of the brake caliper relative to a brake carrier. For this purpose, the sensor device preferably has a further sensing element, the displacement of which is detected and which bears against the brake carrier. The further sensing element detects the position of the brake caliper relative to the Brake carrier and thus the "floating movement" of the brake caliper. This movement is accordingly a measure of the wear of the outer brake pad. Together with the probe element mentioned above, which accumulates wear both

Brake pads recorded, the individual wear of each of the

Brake pads are determined.

In a further advantageous embodiment of the measuring system, a radio transmitter is provided, for example in the sensor device, in order to wirelessly output detected values and / or information calculated from them. Further points the

Sensor device preferably has a battery, possibly a rechargeable battery, for energy supply. The sensor device becomes self-sufficient with the battery

It supplies energy, which enables the measuring system to be easily retrofitted, even if an on-board power supply is not available on a brake to be retrofitted.

The invention is explained in more detail below on the basis of exemplary embodiments with the aid of figures. The figures show:

Fig. 1 a part of a friction brake with a measuring system in a first

Embodiment in a supervision;

1 b shows the arrangement from FIG. 1 a in an isometric view; 2a shows a part of a friction brake with a measuring system in a second

Embodiment in a supervision; 2b shows the arrangement from FIG. 2a in an isometric view; 3a shows a part of a friction brake with a measuring system in a third

Embodiment in a supervision;

3b shows the arrangement from FIG. 3a in an isometric view;

Fig. 4 shows a part of a friction brake with a measuring system in a fourth

Embodiment in a supervision;

5a shows a part of a friction brake with a measuring system in a fifth

Embodiment in a supervision;

5b shows a schematic drawing of the measuring system according to FIG. 5a; and 6 shows a schematic drawing of a sensor device of a measuring system for determining wear of a brake lining

Friction brake.

1 shows a part of a friction brake of a commercial vehicle, for example a trailer, in a top view.

The brake shown is a disc brake, the basic principle shown in this application also being transferable to a drum brake. The brake has a brake caliper 1, which is designed as a floating brake caliper, which holds two brake pads 2, which are mounted on brake pad carriers 3. The brake pad carriers 3 are held in position within the brake caliper 1 with the aid of folded springs 4. Of the brake pads 2, the one shown on the left in FIG. 1 a is fixedly mounted in the brake caliper 1 and is arranged on the outer side of the vehicle. It is also referred to below as the outer brake pad 2. The brake lining 2 shown on the right, which is arranged on the inside of the vehicle, is accordingly also referred to below as the inner brake lining 2. An application device 5 acts on it, by means of which it can be moved towards the outer brake pad 2. The brake disk 6, which is connected to the wheel or a wheel axle and onto which the brake pads 2 are pressed by the application device 5, is arranged between the brake pads 2.

The brake shown is supplemented by a retrofittable measuring system for detecting wear of the brake pads 2. This measuring system includes one

Sensor device 10, using a bracket 11 and a

Fastening element, in the present case a screw, to a suitable location on the

Brake caliper 1 is mounted. Another fastening element 13, which in the present case is designed as a stop and is supported against a contour of the brake caliper 1, ensures a defined positioning of the sensor device 10 on the brake caliper 1. By using the holding bracket 11, an attachment option in the area of the sensor device 10 that is already present can be selected, for example an existing threaded hole or the like. The holding bracket 11 allows a corresponding flexibility for positioning the sensor device 10 and for using existing fastening options. A sensor element 14 is arranged on the sensor device 10, the free end of which is on a rear side, ie the side opposite the brake lining 2, of the

Brake pad carrier 3 of the inner brake pad 2 presses. In the sensor device 10, the sensing element 14 is connected to a sliding element which can be displaced linearly in the longitudinal direction of the sensor device 10 and which is subjected to spring force to the front, i.e. extends in the direction of the brake disc 6 from the housing of the sensor device 10. Furthermore, a sensor is arranged in the sensor device 10 which detects the

Longitudinal position of the sliding element detected.

The sensor can be designed in various ways and for example

work potentiometrically, i.e. via a change in resistance, or be a capacitive position sensor. Also optical sensors that detect a change in position of the longitudinal element on the basis of coding information and / or coloring or

Detection of brightness gradients on the sliding element can be used. Furthermore, a magnetic position detection via an induction measurement and / or a measurement of a magnetic field of a moving permanent magnet, e.g. B. via a Hall sensor, conceivable. Another suitable functional principle that uses a force sensor is described in connection with FIGS. 3a, b.

When the brake pads 2 wear, the position of the brake pad carrier 3 of the inner brake pad 2 relative to the brake caliper 1 changes, and thus the distance to the sensor device 10. This change in distance is determined by the sensor of the sensor device 10 via the feeler element 14 and the linear slide. It is a measure of the accumulated wear or the remaining lining thickness of both brake linings 2.

The sensor device 10 is preferably supplied with the necessary operating current via an autonomous energy supply, for example an inserted battery. The wear measure is also preferably output wirelessly via a

Radio link. For everyone shown within this application

Exemplary embodiments of the sensor device 10 are explained in detail for radio transmission in connection with FIG. 6.

2a and 2b is a second in the same way as in FIGS. 1a and 1b

Embodiment of a measuring system for determining a degree of wear shown, which is used retrofitted on the same brake as in Fig. 1 a, b. With regard to the structure of the brake and also the basic principle of the measuring system, reference is made to the first embodiment.

In addition to the feeler element 14, which in turn is coupled to a linearly displaceable element and a sensor in the sensor device 10 and which detects the position of the brake pad carrier 3 of the inner brake pad 2 relative to the sensor device 10, there is a further feeler element 15 with its free end probes the brake carrier on which the brake caliper 1 is mounted floating. The further sensing element 15 is connected to a further linear slide in the sensor device 10, the position of which is detected by a further sensor.

As in the first exemplary embodiment, the arrangement shown enables detection of the cumulative wear dimension of both brake linings 2 with the aid of the pushbutton element 14. The further pushbutton element 15 detects the movement of the brake caliper 1 with respect to the brake carrier. This movement is a measure of the wear of the outer brake pad 2. The individual wear of each of the brake pads 2 can thus be determined with the aid of the two sensor information recorded.

3a and 3b is again in the same way as in the previous ones

Embodiments shown a third embodiment. Regarding the basic structure of the brake, reference is made to the embodiment of the first embodiment.

In this third exemplary embodiment, a sensor device 10 with a particularly short design in the direction of the linear movement of the probe element 14 is used. For this reason, the sensor element 10 can be approximately in the center of the

Brake pad 2 may be mounted so that the probing on the inner brake pad 2 takes place essentially centrally of the transverse axis. In this way, tilting and / or misalignment effects on the measured distance from the inner brake pad 2 can be minimized.

Due to the positioning of the sensor device 10, the sensing element 14 can be straight and not angled, as shown in those previously

Embodiments. In this way, easier management of the

Sliding element can be implemented in the sensor device 10, since the tilting element 14 does not exert any tilting moments on this sliding element. The feeler element 14 can also represent the linearly displaceable element in the sensor device in this sense.

The particularly short design of the sensor device 10 shown is possible, for example, by using a force measuring sensor to detect the position of the sensing element 14. The force sensor is inside the housing

Sensor device 10 arranged on a side opposite the probe element 14. The feeler element 14 is pressed out of the housing of the sensor device 10 by means of a compression spring and is therefore on the back of the

Brake pad carrier 3. The compression spring mentioned is supported with her

opposite end on the force sensor. Due to the linear force / displacement relationship of the compression spring, the position of the feeler element 14 can be inferred from the measured force. As an alternative to this, a contactless measurement of the position of the probe element 14 within the sensor device 10 is also conceivable, for example optically or also via ultrasound sensors. In this case, regardless of the measuring principle, a compression spring can be provided in order to press the feeler element 14 against the brake pad carrier. Alternatively, provision can also be made to connect the sensing element 14 to the brake pad carrier 3, for example

form-fitting by hanging or snapping into a suitable counter contour, which the brake pad carrier 3 provides.

4 shows a further exemplary embodiment of a brake with a measuring system in a plan view. With regard to the basic structure of the brake and the sensor device, reference is again made to the description of the preceding exemplary embodiments. In the exemplary embodiment shown, the position of the brake pad carrier 3 is not touched directly by the feeler element 14, but rather via a fleece kinematics. For this purpose, a two-sided lever 16 with a free end with the brake pad carrier 3 and with its other free end with the

Touch element 14 connected. The lever 16 is rotatably mounted in a fleece bearing 17 between the two connection points.

The axial change in position, which the brake pad plate 3 passes through due to the wear of the brake pads 2, can be reduced to a smaller amount by the lever 16

Transfer path range of the probe element 14. This tends to result in a large linear movement towards the range of movement of conventional linear sensors, for example, linear potentiometers or Hall sensors that can be used as sensors. In addition to the lever bearing 17 shown, the

lever kinematics described are additionally stabilized and fixed by additional guide elements, which are not shown in FIG. 4.

5a shows, in the same way as FIG. 4a, a further exemplary embodiment of a brake with a measuring system for measuring wear. Regarding the basic structure of the brake, reference is made to the above description.

In the exemplary embodiments described above, one was used

Shown sensor device 10, the sensing element 14 or further sensing element 15 has pressed against the element to be sensed, the brake pad carrier 3. 5a shows a sensor device 10 with a probe element 14, which is on the

Brake pad carrier 3 is attached and on which a train is exerted by the sensor device 10. A possible embodiment of such a sensor device 10 with a push-button element 14 operating in tension is shown in FIG. 5b in a schematic schematic diagram.

The feeler element 14 has a pull cable 18 which is guided into the sensor device 10. A cable drum 19 is arranged in the sensor device 10, onto which the traction cable 18 is rolled up and which acts on the traction cable 18 by spring force. For this purpose, a spiral spring, not shown in FIG. 5b, can be inserted in the cable drum 19. The cable drum 19 converts a linear movement along the direction of the pulling cable 18 into a rotary movement, which is detected by a corresponding sensor, for example a rotary potentiometer. In order to protect the traction cable 18 from the harsh environmental conditions in the area of the brake

For example, a guide through a telescopic spring can be used as a guide element. The telescopic spring surrounding the pull rope 18 protects the wire rope inside and is able to move in and out with the movement of the feeler element 14. Instead of a telescopic spring, a rubber bellows or a similar elastic element can also be provided to protect the pull cable 18.

6 shows an example of the internal structure of a sensor device 10 in one

Embodiment shown. The sensor device 10 shown can be used, for example, in one of the exemplary embodiments of a measuring system in FIGS. 1 a to 4 become. As an example, the sensor device 10 is designed with a straight sensing element 14, as is used in the exemplary embodiment in FIGS. 3a and 3b. However, the sensor device 10 according to FIG. 6 can also have an angled one

Probe 14 may be provided. In the embodiment according to FIG. 6 this is possible

Probe element 14 in a sliding element over (or represents the sliding element), which is guided linearly displaceably in a linear guide 20 inside the sensor device 10. It is biased by means of a compression spring 21, so that the

Push button 14 against the component whose position is to be detected.

There is also a sensor 22 which detects the linear position of the sliding element or the feeler element 14. This can be a linear potentiometer, for example.

Information or signals from sensor 22 are evaluated by an evaluation unit 23. This converts the information from the sensor into an indication of the position of the sensing element 14. The evaluation unit 23 transfers the determined

Position information to a radio transmitter 24, which transmits this information continuously or wirelessly at certain time intervals to a receiver, not shown here. Due to the radio transmission of the detected position information, the sensor device 10 can be easily retrofitted. Furthermore, a battery 25, which may be rechargeable, is provided for the energy supply to the sensor device 10 and supplies both the evaluation unit 23 including the sensor 22 and the radio transmitter 24 with energy. This self-sufficient energy supply to the sensor device 10 also makes it easy to retrofit, even on axles or brakes, in the immediate vicinity of which none

Power lines are on the vehicle.

REFERENCES

1 brake caliper

2 brake pads

3 brake pad carriers

4 retaining spring

5 application device

6 brake pads

10 sensor device

11 retaining bracket

12 fastener

13 additional fastener

14 probe element

15 additional touch element

16 transmission levers

17 lever bearings

18 pull rope

19 rope drum

20 linear guide

21 compression spring

22 sensor

23 evaluation unit

24 radio transmitters

25 battery

Claims

PATENT CLAIMS

1. Retrofittable measuring system for determining wear of a

Brake pad (2) of a friction brake, comprising a sensor device (10) for detecting a position of a brake pad carrier (3) relative to another component of the friction brake, characterized in that the

Sensor device (10) is designed to have at least three different ones

Detect positions of the brake pad carrier (3) distinguishable.

2. Retrofittable measuring system according to claim 1, wherein the friction brake is a disc brake and the further component, relative to which the position of the brake pad carrier (3) is detected, a brake caliper (1).

3. Retrofittable measuring system according to claim 1 or 2, wherein the

Sensor device (10) is designed to distinguishably detect a large number of different positions of the brake lining carrier (3).

4. Retrofittable measuring system according to claim 3, wherein the sensor device (10) is designed to detect a position value for the brake lining carrier (3) based on the further component of the friction brake.

5. Retrofittable measuring system according to one of claims 1 to 4, in which the

Sensor device (10) has a linearly displaceable sensing element (14), the displacement of which is detected and which rests on the brake lining carrier (3).

6. Retrofittable measuring system according to claim 5, wherein the probe element (14) is spring-loaded in order to rest with a pressure force on the brake pad carrier (3).

7. retrofittable measuring system according to claim 5 or 6, wherein the probe element (14) is straight or one or more angled or curved to to extend from the position of the sensor device (10) to the brake lining carrier (3).

8. Retrofittable measuring system according to claim 5, wherein the probe element (14) comprises a pull cable (19) which is tensioned by spring force, a free end of the probe element (14) being fastened to the brake pad carrier (3).

9. Retrofittable measuring system according to one of claims 1 to 8, in which the

Sensor device (10) is fastened to the further component of the friction brake via a holding bracket (11).

10. Retrofittable measuring system according to one of claims 5 to 9, in which the

Sensor device (10) has a sensor (22) for detecting a position of the linearly displaceable probe element (14).

11. Retrofittable measuring system according to claim 10, wherein the sensor (22)

works potentiometrically, capacitively, inductively, optically or via ultrasound.

12. Retrofittable measuring system according to one of claims 2 to 11, wherein the sensor device (10) is designed to detect a position of the brake caliper (1) relative to a brake carrier.

13. Retrofittable measuring system according to claim 12, wherein the sensor device (10) has a further probe element (15), the displacement of which is detected, and which bears against the brake carrier.

14. Retrofittable measuring system according to one of claims 1 to 13, in which the sensor device (10) detected values and / or calculated from them

Outputs information wirelessly.

15. Retrofittable measuring system according to claim 14, wherein the sensor device (10) has a battery (25) for energy supply.