Method for detecting the state of a brake, brake and brake system provided with the brake

Abstract

A method for detecting the state of a brake, a brake, and a brake system provided with such a brake. There is provided a method for detecting the state of a brake (2), a brake, and a brake system provided with such a brake. The method includes the steps of moving an actuating member (9) of a brake actuator (6) in a direction in which a friction element (5) coupled to the actuating member (9) is moved in an actuating direction toward a braking target element (4), and detecting a position of the actuating member (9) as a first corner position at which contact of the friction element (5) with the braking target element (4) is identified by a force starting to increase.

Description

Technical Field

[0001] The present invention relates to a method for detecting the state of a brake, a brake, and a brake system equipped with the brake, particularly in relation to railway vehicles.

[0002] The identification of wear of the friction material in a disc brake, i.e., wear of the brake disc and brake pads, has hitherto generally been carried out in the field of railway vehicles by visual inspection by maintenance personnel, but this involves significant costs.

[0003] However, wear of the friction material can also be measured by an image processing device ("train scanner") incorporated in a fixed position on the track bed, or by sensors incorporated in the vehicle or its brake controller. However, the use of an image processing device incurs significant costs and, as described above, has the problem of being fixed in position and thus not flexible. These sensors also involve significant costs and are more prone to failure.

[0004] Another possibility for identifying wear of the friction material is a wear calculation program that utilizes system parameters identified from measured quantities, such as braking force and vehicle speed, to calculate wear based on a model based on the converted braking energy. However, these calculations can be very inaccurate.

[0005] The function of the wear adjustment device for ensuring the brake despite wear can only be confirmed when the required braking action can no longer be obtained.

[0006] Therefore, the underlying problem of the present invention is to solve the above-mentioned drawbacks and provide a method and a brake for identifying the state of the brake in a cost-effective and reliable manner.

[0007] This problem is solved by the method according to claim 1, the brake according to claim 10, and the brake system according to claim 13. Advantageous developments are included in the dependent claims.

[0008] According to one aspect of the present invention, a method for detecting the state of a brake comprises the following steps, namely: - moving the actuating member of the brake actuator in a direction in which the friction element coupled to the actuating member moves in the direction of action towards the element to be braked; - detecting the position of the actuating member as a first corner position at which the contact of the friction element with the element to be braked is identified by the force in the actuating member starting to increase.

[0009] These steps form the basis for detecting the state of the brake without the need to incorporate additional sensors in the brake controller, in particular in the region of the element to be braked, i.e. the brake disc region, and also in the region of the braking element, i.e. the brake pad region, without such sensors being required.

[0010] The electromechanical drive as a drive device has a position measuring unit and a force measuring unit. For example, the position can be determined indirectly via the rotation of the motor. In the case of a DC motor rectified electrically, an angle sensor is required. The position of the brake cylinder can be estimated via the rotation of the motor and the gear ratio of the actuating member. The measurement of the force of the brake cylinder is necessary for controlling the braking force in a railway vehicle brake system, where the force of the brake cylinder is determined here in an electromechanical brake system via a dedicated force sensor or via the motor torque. The motor torque can be determined via the phase current, which is usually a known quantity. In the case of a pneumatic cylinder or a hydraulic cylinder, corresponding sensors can be provided thereon or in the braking mechanism.

[0011] In an advantageous embodiment of the method, the distance of the actuating member from the rest position to the first corner position corresponds to the relevant spacing of the friction element from the element to be braked, and wear is compensated such that the relevant spacing is within a predefined tolerance range. This embodiment of the method includes the following step, namely, after a predefined number of braking processes, determining the functionality of the wear adjustment device by determining, via the distance of the actuating member, that the relevant spacing is within a predefined tolerance range.

[0012] After a predefined number of braking processes, when it is determined, via the distance of the actuating member from the rest position to the first corner position, that a predefined spacing is within a predefined tolerance range, the functionality of the adjustment mechanism, i.e., the guarantee of adjustment and thus the reliable deceleration of the railway vehicle, can thereby be determined.

[0013] In another advantageous embodiment of the method, the method includes the following steps, namely, - continuing to move the actuating member and the friction element coupled to the actuating member in the direction of action to form a braking process, - moving the actuating member and the friction element coupled to the actuating member in the direction opposite to the direction of action to end the braking process, and - detecting the position of the actuating member as the second corner position where the lifting of the friction element from the element to be braked is identified by the end of the force reduction in the actuating member.

[0014] These additional steps form the basis for detecting another state of the brake without the need to incorporate additional sensors in the brake controller, in particular in the region of the element to be braked, in particular in the region of the brake disc, and also in the region of the braking element, in particular the brake pad.

[0015] In one advantageous embodiment of the method, the method includes the following step, i.e., the step of identifying the wear of the friction element and the element to be braked by calculating the difference in position between the first corner position and the second corner position.

[0016] In particular, at this time, it is possible to identify the wear that actually occurs during the last braking process of the friction element and the element to be braked without the need to provide, for example, a sensor or an image processing device in the friction element. At this time, the wear state of the entire friction material is identified. From empirical values, the wear distribution of the element to be braked and the friction element can be identified.

[0017] In another advantageous embodiment of the method, the method includes the following step, i.e., the step of obtaining the total wear of the friction element and the element to be braked by adding up the wear of the friction element and the element to be braked after a plurality of braking processes.

[0018] What this step enables is, for example, to identify the overall wear after, for example, replacing the friction material in order to signal preventive maintenance.

[0019] In another advantageous embodiment of the method, after each braking process, the total wear of the friction element and the element to be braked is obtained.

[0020] What this enables is, for example, to accurately identify the progress of wear even under detected ambient conditions such as the speed or weight of a railway vehicle.

[0021] In another advantageous embodiment of the method, the method includes the following step, i.e., the step of identifying the thermal expansion of the friction element and the element to be braked by calculating the difference in position between the first corner position and the second corner position.

[0022] By identifying the thermal expansion of the friction element and the element to be braked, and thereby identifying the overall expansion of the two elements, it is possible to estimate, for example, the thermal load on the brake.

[0023] In another aspect of the present invention, the brake has a brake actuator, a friction element, and an element to be braked. The element to be braked has a brake actuator and is configured to move the friction element in the acting direction toward the element to be braked for the braking process and to move the friction element away from the element to be braked in the direction opposite to the acting direction to end the braking process depending on the movement of the actuating member of the brake actuator. The brake actuator is configured to detect the force exerted on the friction element along the acting direction and the position of the friction element along the acting direction using the force exerted on the actuating member of the brake actuator and the position of the actuating member via a braking mechanism.

[0024] With this brake, the state of the brake can be detected without the need for additional sensors or image processing devices in the region of the element to be braked, particularly in the region of the brake disc, and also in the region of the braking element, particularly the brake pad.

[0025] Corresponding to an advantageous embodiment of the brake, the brake is configured to implement the method described above, thereby achieving the advantages described above.

[0026] In another advantageous embodiment of the brake, where the braking mechanism has a wear adjustment device, the brake is configured to implement one of the plurality of methods described above with wear compensation, thereby achieving the advantages described above.

[0027] According to another aspect of the present invention, a brake system has a brake and a control device configured to drive and control the brake. The control device is configured to evaluate and process the detected first corner position and second corner position.

[0028] Hereinafter, the present invention will be described based on embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0030] FIG. 1 shows a basic diagram of a brake system 1 equipped with an electromechanical brake 2 and a control device 3. In an alternative embodiment, the brake is configured as a pneumatic brake or a hydraulic brake instead of an electromechanical brake.

[0031] The electromechanical brake 2 has a brake disk as a braking target element 4 and a brake pad as a friction element 5. The electromechanical brake 2 further has an electromechanical brake actuator 6 coupled to the braking mechanism 7 and the wear adjustment device 8 of the electromechanical brake 2 by an eccentric shaft. In an alternative embodiment, the brake disk may be replaced by a wheel body or a brake drum. In another alternative embodiment, only one friction element 5 is provided or more than two friction elements 5 are provided. Correspondingly, in an alternative embodiment where the brake is configured as a pneumatic brake or a hydraulic brake, a pneumatic brake actuator or a hydraulic brake actuator is provided.

[0032] In the present embodiment, the electromechanical brake actuator 6 is implemented as an electromechanical cylinder having a piston rod as the actuating member 9. In an alternative embodiment, the electromechanical brake actuator 6 may be implemented as a rotary cylinder, for example. The position of the piston rod is determined indirectly via the rotation of the motor of the electromechanical brake actuator 6 and via an angle sensor, and the position of the brake cylinder is estimated via the rotation of the motor and the gear ratio of the actuating member. In an alternative embodiment, the position of the actuating member 9 can also be detected via a distance sensor in a pneumatic cylinder or a hydraulic cylinder, or at another location of the braking mechanism 7, for example in an eccentric body which will be described later.

[0033] When the piston rod extends, the eccentric body is deflected via a lever, and this eccentric body is supported within the braking mechanism 7 such that the friction element 5 directly coupled to the eccentric body is moved in the actuating direction towards the element to be braked 4. When this friction element 5 is supported by the element to be braked 4, when the piston rod continues to extend, the entire braking mechanism 7 is shifted, and the other friction element 5 is also moved in its actuating direction towards the element to be braked 4 and abuts there. When the piston rod continues to extend further, the braking force of the electromechanical brake 2 is formed in the braking process. To end the braking process, the piston rod retracts again into the electromechanical brake actuator 6, whereby the friction element 5 is moved away from the element to be braked 4.

[0034] On the one hand, the electromechanical brake actuator 6 is driven and controlled by the control device 3 to generate the required braking force. On the other hand, the electromechanical brake actuator 6 uses the force exerted on the actuating member 9 of the electromechanical brake actuator and the position of the actuating member 9 to supply data on the force exerted on the friction element 5 along the acting direction and the position of the friction element 5 along the acting direction to the control device 3. In an alternative embodiment, these data are supplied not to the control device 3 that drives and controls the electromechanical brake actuator 6, but to a separate evaluation device. In another alternative embodiment, the control device 3 is incorporated in the electromechanical brake actuator 6. In another alternative embodiment, the data on the position and force are supplied not by the electromechanical brake actuator 6, but by a sensor in the braking mechanism 7.

[0035] The wear adjustment device 8 identifies the time when the braking target element 4 and / or the friction element 5 wears, and automatically compensates for the wear as known in the prior art. The wear compensation is performed when the friction element 5 moves towards the braking target element 4 or when the friction element 5 moves away from the braking target element 4.

[0036] FIG. 2 shows a basic diagram of the piston position and piston force of the piston as the actuating member 9 of the electromechanical brake actuator 6 of the electromechanical brake 2 when there is no brake wear.

[0037] The upper bar graph shows the piston position, that is, the distance of the actuating member 9, depending on its action.

[0038] Starting from the piston position of 0 mm as the stationary position of the actuating member 9, an idle stroke LH is performed up to an extended piston position of 17 mm. The idle stroke LH is the stroke that the piston must travel from the stationary position to bring the friction element 5 into contact with the braking target element 4.

[0039] Following the idle stroke LH, a so-called elastic stroke EH is performed. The elastic stroke EH is a stroke in which the piston must travel in order to compensate for the elasticity of the braking system when forming a force between the friction element 5 and the element to be braked 4. The elasticity of the braking system is a substantially constant, particularly linear system characteristic. The elastic stroke EH depends on the braking force and is 22 mm in this embodiment. The braking process is carried out by the elastic stroke EH.

[0040] To end the braking process, the elastic stroke -EH in the opposite direction is again performed with a piston stroke of 22 mm, followed by a piston stroke of 17 mm again as the opposite idle stroke -LH, whereby the friction element 5 is again in its original position and the piston as the actuating member 9 is again in the stationary position as before.

[0041] In the lower graph, the piston force progression depending on the piston position can be observed. The force-distance progression is indicated by the thick solid line. For reasons of illustration, the idle strokes LH, -LH and the elastic stroke EH, -EH are shown beside the thick solid line, but are actually located on the thick solid line. Similar to the upper graph, it can also be observed here that the idle stroke LH is carried out up to a piston position of 17 mm, no force is applied to the friction element 5, and thus the piston force remains at "0" as well. As soon as the friction element 5 comes into contact with the element to be braked 4, the piston force increases during the elastic stroke EH. The position of the piston where the friction element 5 abuts against the element to be braked 4, i.e., where the piston force begins to rise, is referred to as the first corner position. In this case, the piston extends by 22 mm up to a piston position of 39 mm in order to achieve the currently desired braking force. To end the braking process, the friction element 5 is moved in the opposite direction, whereby the piston force decreases again up to the piston position where the friction element 5 lifts off from the element to be braked 4, and thus the piston force remains at "0" again. The position of the piston where the friction element 5 lifts off from the element to be braked 4, i.e., where the piston force remains constant at "0" in this case, is referred to as the second corner position. That is, in the case of no wear, the second corner position coincides with the first corner position.

[0042] That is, the first corner position is detected by detecting that the force begins to increase. The second corner position is detected by detecting a constant force progression after the force has decreased.

[0043] The force progression is shown here idealized as a straight line. However, in reality, the force progression has an unstable progression due to the friction and inertia of the components involved, and this progression is smoothed and / or averaged by the corresponding algorithm in order to be evaluable.

[0044] Figure 3 shows the basic diagram of the piston position and the piston force in the case of brake wear.

[0045] As can already be seen in the graph of FIG. 2, the idle stroke LH is carried out up to a piston position of 17 mm, and the elastic stroke of 22 mm, i.e., up to a piston position of 39 mm, is carried out. For example, during a relatively long downhill driving, for example, due to a relatively long and continuous braking process, the friction element 5 and / or the braking target element 4 are worn, and thus, in order to maintain the required braking force, it is necessary to carry out an additional wear stroke VH. The wear stroke VH is the stroke that the piston must travel in order to compensate for the wear of the friction material, i.e., the friction element 5 and the braking target element 4, during braking so that the desired braking force is maintained. The wear stroke VH is 3 mm in this embodiment, i.e., up to a piston stroke of 42 mm. In this case, in order to end the braking process, the friction element 5 is moved in the opposite direction again, whereby the piston force is reduced again up to the piston position where the friction element 5 lifts off from the braking target element 4. Since the elastic stroke EH / -EH of 22 mm is a constant system characteristic, i.e., the friction element 5 lifts off from the braking target element 4 at a piston position of 20 mm, which is here the second corner position. Subsequently, the actuating member 9 travels back to the rest position, here covering a distance of 20 mm, i.e., the 17 mm distance of -LH and the 3 mm distance of -VH. That is, the second corner position is in this case 3 mm different from the first position, which corresponds to the wear stroke VH and corresponds to the wear of the braking target element 4 and the friction element 5.

[0046] FIG. 4 shows a basic diagram of the piston position when adjusted after brake wear.

[0047] The illustration of the upper bar graph corresponds to the illustration of the upper bar graph in FIG. 3, and thus during braking, wear of the braking target element 4 and the friction element 5 occurs. Also visible here is that the return stroke -LH-VH corresponds to -20 mm, i.e., the wear corresponding to a piston distance of 3 mm has not yet been compensated. Following this braking process, as illustrated in the lower bar graph, basically the next braking process already shown in FIG. 2 is carried out.

[0048] In the lower graph of FIG. 4, the idle stroke LH is likewise 17 mm, and what can be seen from this is that the wear of the final braking process during the idle stroke LH has been compensated for by the wear adjustment device 8 for the next braking process, whereby the idle stroke LH corresponds to the usual idle stroke LH of 17 mm. Alternatively, wear may already be compensated for by the wear adjustment device 8 during the return stroke - LH - VH, in which case this return stroke - LH may also be 17 mm here. Alternatively, furthermore, wear may be compensated for partly during the return stroke - LH and partly during the idle stroke LH in the next braking process.

[0049] FIG. 5 shows a basic diagram of the piston position when the electromechanical brake is thermally expanded.

[0050] Also in this figure, the first part of the braking process corresponds to the braking processes shown in FIGS. 3, 4 and 5 until the desired braking action at present is reached. First, an idle stroke LH with a piston stroke of 17 mm is carried out, and then an elastic stroke EH of 22 mm is carried out.

[0051] During the braking process, due to the kinetic energy converted into heat, thermal expansion occurs in the electromechanical brake 2, particularly in the friction element 5 and the element 4 to be braked. This expansion causes the electromechanical brake actuator 6 to be driven and controlled so that, in order to reduce the braking force to the actually required braking force, the operating member 9 of this electromechanical brake actuator 6 is retracted by a so - called expansion stroke AH. Therefore, the expansion stroke AH is the stroke that the piston must travel in order to keep the braking operating force constant as a result of thermal expansion. In this embodiment, the expansion stroke is - 7 mm.

[0052] As can be seen from the subsequent rod, the elastic stroke - EH is also 22 mm with approximately constant system characteristics in this case. Therefore, the return stroke from the second corner position is obtained from the idle stroke - LH which is only reduced by the expansion stroke AH.

[0053] However, this expansion stroke AH is not compensated, and the original state is re - formed by the cooling of the components of the electromechanical brake 2. As a result, the idle stroke LH shown in the lower rod graph becomes 17 mm again during the next braking process.

[0054] During operation, the method described below for detecting the state of the electromechanical brake is implemented. Corresponding to the strokes shown in FIGS. 2 to 5, the actuating member 9 of the electromechanical brake actuator 6 is moved in a direction in which the friction element 5 coupled to the actuating member 9 is moved in the actuating direction towards the braking target element 4. When the force in the actuating member 9 begins to increase, the position of the actuating member 9 at which the contact of the friction element 5 with the braking target element 4 is identified is detected as the first corner position, and the movement of the friction element 5 is continued in the actuating direction to form the braking process. To end the braking process, the friction element 5 is moved in the direction opposite to the actuating direction. As a result, the force in the actuating member 9 also decreases, and when the decrease in the force in the actuating member ends, the position of the actuating member 9 at which the lifting of the friction element 5 from the braking target element 4 is identified is detected as the second corner position. Using these two corner positions, the state of the electromechanical brake can be detected.

[0055] By calculating the difference in the position of the actuating member 9 at the first corner position and the second corner position, the wear of the friction element 5 and the braking target element 4 can be identified. If there is no difference in position between the first corner position and the second corner position, it can be identified from this that no significant wear has occurred during the last braking process.

[0056] In addition to identifying wear during a single braking process, it is also possible to determine the total wear by adding the wear of the friction element 5 and the element 4 to be braked. To determine the total wear as accurately as possible, this total wear is determined after each braking process ends. In an alternative embodiment, this total wear is determined after a predetermined number of braking processes or, for example, after a predetermined duration has elapsed.

[0057] When the wear of the friction element 5 and the element 4 to be braked exceeds a predetermined limit value, the wear is automatically compensated using the wear adjustment device 8. In this embodiment, this is done via automatic mechanical drive control of the wear adjustment device 8 within the braking mechanism 7. In an alternative embodiment, this drive control may be pneumatic or may use the identification of the wear of the friction element 5 and the element 4 to be braked using the first corner position and the second corner position to drive and control the wear adjustment device to compensate for the wear.

[0058] This compensation can be carried out on the element 4 to be braked during the next braking process during the return stroke of the friction element 5 lifted from the element 4 to be braked or during the idle stroke LH of the friction element 5, as already explained above. Furthermore, it is also possible to partially compensate during the return stroke - LH and partially during the idle stroke LH of the subsequent braking process. Alternatively, instead of the compensation being carried out immediately, it may be carried out in one control process of the next plurality of braking processes or during a plurality of braking processes of the next plurality of braking processes, provided that it is ensured that the wear does not cause functional damage.

[0059] The distance of the actuating member 9 from its rest position to the first corner position corresponds to the relevant interval of the friction element 5 from the element 4 to be braked, and this wear is compensated so that this interval is within a predetermined tolerance range. In an alternative embodiment, instead of being associated with a predetermined tolerance range, the wear is always compensated by a determined amount.

[0060] It is possible when wear is compensated so that the spacing is within a predefined tolerance range, by determining that after a predefined number of braking processes the associated spacing is within the predefined tolerance range, to determine the functionality of the wear adjustment device 8 via the distance of the actuating member 9 from its rest position to the first corner position. Alternatively, it is also possible to determine the functionality of the wear adjustment device 8 via only the first corner position, without determining the wear of the friction element 5 and the element to be braked 4 via the first corner position and the second corner position.

[0061] Furthermore, it is possible to determine the overall thermal expansion of the friction element 5 and the element to be braked 4 by calculating the difference in position between the first corner position and the second corner position before and after the braking process.

[0062] Although the invention has been described in connection with specific features and embodiments, it will be apparent that various modifications and combinations can be made thereto without departing from the spirit and scope of the invention. Accordingly, the description and drawings are to be regarded as illustrative only of the invention as defined by the appended claims, and are intended to cover all modifications, variations, combinations or equivalents included within the scope of the invention.

Explanation of reference numerals

[0063] 1 Brake system 2 Electromechanical brake 3 Control device 4 Element to be braked 5 Friction element 6 Electromechanical brake actuator 7 Braking mechanism 8 Wear adjustment device 9 Actuating member LH, -LH Idle stroke EH, -EH Elastic stroke VH Wear stroke AH Expansion stroke

Claims

1. A method for detecting the state of a brake (2) for a railway vehicle, the method comprising the following steps, namely: moving the actuating member (9) in a direction in which the friction element (5) coupled to the actuating member (9) of the brake actuator (6) is moved in the actuating direction towards the braking target element (4); detecting the position of the actuating member (9) as a first corner position at which the contact of the friction element (5) with the braking target element (4) is identified by the force beginning to increase.

2. The distance of the actuating member (9) from its rest position to the first corner position corresponds to the relevant spacing of the friction element (5) from the braking target element (4), compensating for wear of the friction element (5) and the braking target element (4) such that the relevant spacing is within a predefined tolerance range, the method comprising the following step, namely: after a predefined number of braking processes, specifying the functionality of a wear adjustment device (8) for automatically compensating for the wear by specifying that the relevant spacing is within the predefined tolerance range via the distance of the actuating member (9). The method according to claim 1.

3. continuing the movement in the actuating direction of the actuating member and the friction element (5) coupled to the actuating member to form a braking process; moving the actuating member and the friction element (5) coupled to the actuating member in a direction opposite to the actuating direction to end the braking process; and detecting the position of the actuating member (9) as a second corner position at which the lifting of the friction element (5) from the braking target element (4) is identified by the end of the decrease in force. The method according to claim 1 or 2.

4. specifying the wear of the friction element (5) and the braking target element (4) by calculating the difference in position between the first corner position and the second corner position. The method according to claim 3.

5. determining the total wear of the friction element (5) and the braking target element (4) by adding up the wear of the friction element (5) and the braking target element (4) after a plurality of braking processes. The method according to claim 4.

6. The method according to claim 5, wherein after each braking process, the total wear of the friction element (5) and the element to be braked (4) is determined.

7. The method according to claim 6, wherein the wear is at least partially compensated when the friction element (5) moves away from the element to be braked (4).

8. The method according to claim 5 or 6, wherein the wear is at least partially compensated when the friction element (5) moves towards the element to be braked (4).

9. The method according to any one of claims 3 to 8, having a step of identifying the thermal expansion of the friction element (5) and the element to be braked (4) by calculating the difference in position between the first corner position and the second corner position.

10. A brake (2) for a railway vehicle, a brake actuator (6), a friction element (5), an element to be braked (4), a braking mechanism (7), which has the brake actuator (6) and, depending on the movement of the actuating member (9) of the brake actuator (6), moves the friction element (5) in the actuating direction towards the element to be braked (4) for a braking process, and moves the friction element (5) away from the element to be braked (4) in the opposite direction to the actuating direction to end the braking process, The brake (2) for a railway vehicle, wherein the braking mechanism (7) is configured to detect the force exerted on the friction element (5) along the actuating direction and the position of the friction element (5) along the actuating direction by using the force exerted on the actuating member (9) of the braking mechanism (7) and the position of the actuating member (9).

11. The brake (2) according to claim 10, wherein the brake (2) is configured to perform the method according to any one of claims 1 to 9.

12. The brake (2) according to claim 11, wherein the braking mechanism (7) has a wear adjustment device (8), and the brake (2) is configured to perform the method according to any one of claims 1 to 9 having the features of claim 2.

13. A brake system (1), comprising the brake (2) according to any one of claims 10 to 12, and a control device (3) configured to drive and control the brake (2). The brake system (1), wherein the control device (3) is configured to evaluate and process the detected first corner position and the second corner position.

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