Method for detecting a state of a brake, brake and brake system having a brake

Abstract

The invention relates to a method for detecting a state of a brake (2), to a brake and to a brake system having such a brake. The method comprises the steps of: moving an action element (9) of a brake actuator (6) in a direction in which a friction element (5) connected to the action element (9) is moved in a direction of action towards an element (4) to be braked; detecting, as a first key position, a position of the action element (9), in which, by means of an increase in force, a contacting of the friction element (5) on the element (4) to be braked is identified.

Description

[0001] DESCRIPTION

[0002] Method for detecting a state of a brake, brake and braking system with a brake

[0003] The invention relates to a method for detecting a state of a brake, a brake and a braking system with a brake, in particular in connection with rail vehicles.

[0004] Determining the wear of friction material in disc brakes, namely the wear of the brake disc and the brake pad, has so far usually been carried out in the rail vehicle sector by means of visual inspection by maintenance personnel, which involves a great deal of effort.

[0005] Wear of the friction material can also be measured using image processing devices (train scanners) installed in the track bed or sensors installed in the vehicle or its brake actuator. However, these image processing devices pose the problems of high costs and, as mentioned above, their fixed and thus inflexible nature. The sensors are also expensive and prone to failure.

[0006] Another way to determine friction material wear is with wear calculation programs that use specific system variables, such as braking forces and vehicle speeds, to model wear based on the converted braking energy. However, these calculations can be very inaccurate.

[0007] Furthermore, the functioning of a wear adjustment device to ensure braking despite wear can only be determined when the required braking effect is no longer present. Therefore, the object underlying the invention is to eliminate the above-mentioned disadvantages and to provide a method and a brake that determine the condition of the brake cost-effectively and reliably.

[0008] The object is achieved by a method according to claim 1, a brake according to claim 10 and a braking system according to claim 13. Advantageous further developments are contained in the dependent claims.

[0009] According to one aspect of the invention, a method for detecting a state of a brake comprises the steps of:

[0010] - moving an operating member of a brake actuator in a direction in which a friction element connected to the operating member is moved in an effective direction towards an element to be braked;

[0011] - Detecting a position of the active element in which a contact of the friction element with the element to be braked is detected by an initial increase in force on the active element, as the first corner position.

[0012] These steps form the basis for detecting a state of the brake without the need to install additional sensors in the brake actuator, in particular without such sensors being required in the area of ​​the element to be braked, namely in the area of ​​a brake disc, and in the area of ​​the braking element, namely a brake pad.

[0013] An electromechanical drive as the drive has position and force measurement. For example, the position can be determined indirectly via the rotation of the motor. For electrically commutated DC motors, an angle sensor is required. The position of the brake cylinder can be determined from the rotation of the motor and the ratio of the actuator. A measurement of the brake cylinder force is required in rail vehicle braking systems to control the brake application force. In electromechanical braking systems, the brake cylinder force is determined via dedicated force sensors or via a motor torque. The motor torque can be determined via the phase current, whereby the phase current is usually a known value. In the case of pneumatic or hydraulic cylinders, corresponding sensors can be provided on the cylinder or in a brake mechanism.

[0014] In an advantageous embodiment of the method, in which a travel of the active element from a rest position of the active element to the first corner position corresponds to a corresponding distance of the friction element from the element to be braked, the wear is compensated such that the corresponding distance is within a predetermined tolerance range. This embodiment of the method includes the step of determining a functionality of the wear adjustment device by determining that the corresponding distance is within the predetermined tolerance range after a predetermined number of braking operations, based on the travel of the active element.

[0015] If it is determined via the path of the active element from the rest position of the actuator to the first corner position after the predetermined number of braking operations that the predetermined distance is within the predetermined tolerance range, a functionality of the adjustment mechanism, i.e. ensuring the adjustment and thus a safe deceleration of the rail vehicle, can be determined.

[0016] In a further advantageous embodiment of the method, it comprises the following steps:

[0017] - Continuing the movement of the active member and the associated friction element in the direction of action to generate a braking process;

[0018] - Moving the active member and the associated friction element in the opposite direction of action to terminate the braking process;

[0019] - Detecting a position of the operating element in which a lifting of the friction element from the element to be braked is detected by terminating a force drop on the operating element, as a second corner position.

[0020] These further steps form the basis for detecting further states of the brake without the need to install additional sensors in the brake actuator, in particular without the need for sensors in the area of ​​the element to be braked, in particular in the area of ​​a brake disc, and in the area of ​​the braking element, in particular a brake pad.

[0021] In an advantageous embodiment of the method, it includes the step of determining wear of the friction element and of the element to be braked by calculating the position difference between the first corner position and the second corner position.

[0022] Specifically, the wear of the friction element and the element being braked during the last braking operation can be determined without, for example, the need to install sensors in the friction element or image processing devices. This determines the wear status of the entire friction material. Based on empirical values, a breakdown of the wear of the element being braked and the friction element can be determined.

[0023] According to a further advantageous embodiment of the method, it includes the step of determining a total wear of the friction element and the element to be braked by summing the wear of the friction element and the element to be braked after several braking operations.

[0024] This step makes it possible to determine the total wear, for example since replacing the friction material, in order to signal preventive maintenance, for example.

[0025] In a further advantageous embodiment of the method, the total wear of the friction element and the element to be braked is determined after each braking operation. This enables a precise determination of the wear pattern, even under recorded boundary conditions, such as the speed or weight of the rail vehicle.

[0026] In a further advantageous embodiment of the method, it includes the step of determining a thermal expansion of the friction element and of the element to be braked by calculating the position difference between the first corner position and the second corner position.

[0027] By determining the thermal expansion of the friction element and the element to be braked, whereby the total expansion of both elements is determined, it is possible, for example, to estimate a thermal load on the brake.

[0028] According to a further aspect of the invention, a brake has a brake actuator, a friction element, an element to be braked and a brake mechanism which has the brake actuator and which is designed to move the friction element in an effective direction towards the element to be braked for a braking operation as a function of a movement of an active element of the brake actuator and to move the friction element away from the element to be braked in the opposite direction to the effective direction to end the braking operation, and the brake actuator is designed to detect, via the brake mechanism, a force exerted on the friction element along the effective direction and a position of the friction element along the effective direction by means of a force exerted on an active element of the brake actuator and a position of the active element.

[0029] With this brake, its condition can be detected without the need for additional sensors in the area of ​​the element to be braked, in particular in the area of ​​a brake disc, and in the area of ​​the braking element, in particular a brake pad, or image processing devices. According to an advantageous embodiment of the brake, it is designed to carry out the above-mentioned method, thereby achieving the above-mentioned advantages.

[0030] In another advantageous embodiment of the brake, wherein the brake mechanism has a wear adjustment device, the brake is designed to carry out one of the above-mentioned methods with a compensation of the wear, whereby the above-mentioned advantages can be achieved.

[0031] According to a further aspect of the invention, a braking system comprises a brake and a control device configured to control the brake, wherein the control device is configured to evaluate and process the detected first corner position and second corner position.

[0032] The invention is explained below using exemplary embodiments with reference to the accompanying drawings.

[0033] In particular,

[0034] Fig. 1 : a schematic diagram of a braking system with an electro-mechanical brake;

[0035] Fig. 2 shows schematic representations of a piston position and a piston force of a piston of an electro-mechanical brake actuator of the electromechanical brake in a case without brake wear;

[0036] Fig. 3 basic representations of the piston position and the piston force in a case with brake wear;

[0037] Fig. 4 shows basic representations of the piston position in a case of adjustment after brake wear; and Fig. 5 shows basic representations of the piston position in a case of thermal expansion of the electro-mechanical brake.

[0038] Fig. 1 shows a schematic diagram of a braking system 1 with an electromechanical brake 2 and a control device 3. In alternative embodiments, the brake is not designed as an electromechanical brake, but as a pneumatic or hydraulic brake.

[0039] The electromechanical brake 2 comprises a brake disc as an element 4 to be braked and brake pads as friction elements 5. Furthermore, the electromechanical brake 2 comprises an electromechanical brake actuator 6, which is connected by means of an eccentric shaft to a brake mechanism 7 of the electromechanical brake 2 and to a wear adjustment device 8. In alternative embodiments, the brake disc can also be replaced by a wheel body or a brake drum. In further alternative embodiments, only one friction element 5 or more than two friction elements 5 are provided. In the alternative embodiments in which the brake is designed as a pneumatic or hydraulic brake, a pneumatic or hydraulic brake actuator is provided accordingly.

[0040] In this embodiment, the electromechanical brake actuator 6 is designed as an electromechanical cylinder with a piston rod as an actuating element 9. In alternative embodiments, the electromechanical brake actuator 6 can also be designed, for example, as a rotary cylinder. The position of the piston rod is determined indirectly via the rotation of the motor of the electromechanical brake actuator 6 using an angle sensor, with the position of the brake cylinder being determined via the rotation of the motor and the ratio of the actuator. In alternative embodiments, the position of the actuating element 9 can also be detected via displacement sensors on the pneumatic or hydraulic cylinder or at another location in the brake mechanism 7, for example, on an eccentric described below.By extending the piston rod, an eccentric is deflected via a lever, which is supported within the brake mechanism 7 in such a way that the friction element 5, which is directly connected to the eccentric, is moved in an effective direction towards the element 4 to be braked. When this friction element 5 is supported on the element 4 to be braked, the entire brake mechanism 7 is displaced with continued extension of the piston rod in such a way that the other friction element 5 also moves in its effective direction towards the element 4 to be braked and rests there. With a subsequent further extension of the piston rod, the braking force of the electro-mechanical brake 2 is generated in a braking process. To end the braking process, the piston rod retracts into the electro-mechanical brake actuator 6, whereby the friction elements 5 are moved away from the element 4 to be braked.

[0041] The electromechanical brake actuator 6 is, on the one hand, controlled by the control device 3 to generate the required braking force. On the other hand, the electromechanical brake actuator 6 supplies the control device 3 with data about a force exerted on the friction element 5 along the direction of action and about a position of the friction element 5 along the direction of action by means of a force exerted on the actuating element 9 of the electromechanical brake actuator and a position of the actuating element 9. In alternative embodiments, the data is not provided to the control device 3, which controls the electromechanical brake actuator 6, but rather to a separate evaluation device. In further alternative embodiments, the control device 3 is integrated into the electromechanical brake actuator 6.In other alternative embodiments, the data regarding position and force are not provided by the electromechanical brake actuator 6, but by sensors within the brake mechanism 7.

[0042] The wear adjustment device 8 detects when the element 4 to be braked and / or the friction elements 5 are wearing and, as is known in the art, automatically compensates for the wear. Compensation for the wear occurs either when the friction elements 5 move toward the element 4 to be braked or when the friction elements 5 move away from the element 4 to be braked.

[0043] Fig. 2 shows basic representations of a piston position and a piston force of a piston as the active element 9 of the electro-mechanical brake actuator 6 of the electromechanical brake 2 in a case without brake wear.

[0044] The upper bar chart shows piston positions, i.e. paths of the actuator 9, depending on their effect.

[0045] Starting from the piston position of 0 mm as a rest position of the actuator 9, an idle stroke LH is performed up to an extended piston position of 17 mm. The idle stroke LH is a stroke that must be traveled by the piston from the rest position in order to bring the friction elements 5 into contact with the element 4 to be braked.

[0046] Following the idle stroke LH, a so-called elastic stroke EH is performed. The elastic stroke EH is a stroke that must be traveled by the piston to compensate for the elasticity of the braking system when a force builds up between the friction elements 5 and the element 4 to be braked. The elasticity of the braking system is an approximately constant, particularly linear, system property. The elastic stroke EH depends on the braking force and, in this example, is 22 mm. The braking process is carried out using the elastic stroke EH.

[0047] To end the braking process, the elastic stroke is again carried out in the reverse direction -EH by a piston stroke of 22 mm and subsequently a piston stroke of 17 mm is carried out as the reverse idle stroke -LH, so that the friction elements 5 are again in their original position and the piston as the active member 9 is again in its rest position.

[0048] The lower diagram shows a piston force curve as a function of the piston position. The force-displacement curve is represented by the solid thick line. For clarity, the idle strokes LH, -LH and the elastic strokes EH, -EH are drawn next to the solid thick line, but are actually located on the solid thick line. As in the upper diagram, it can be seen here that the idle stroke LH occurs up to a piston position of 17 mm, whereby no force is applied to the friction elements 5 and thus the piston force also remains at "0". As soon as the friction elements 5 come into contact with the element 4 to be braked, the piston force increases during the elastic stroke EH. The position of the piston at which the friction elements 5 contact the element 4 to be braked, i.e. the piston force begins to increase, is referred to as the first corner position.In this case, the piston is extended by 22 mm to a piston position of 39 mm in order to achieve the currently desired braking force. To end the braking process, the friction elements 5 are moved in the other direction, which again reduces the piston force, down to the piston position at which the friction elements 5 lift off the element 4 to be braked, so that the piston force again remains constant at "0". The position of the piston at which the friction elements 5 lift off the element 4 to be braked, from which the piston force then remains constant at "0", is referred to as the second corner position. In the case of no wear, the second corner position corresponds to the first corner position.

[0049] The first corner position is thus detected by detecting an initial increase in force. The second corner position is detected by detecting a constant force curve after a decrease in force.

[0050] The force curves are idealized here as straight lines. In reality, however, the force curves exhibit a turbulent pattern due to friction and inertia of the components involved, which is smoothed and / or averaged using appropriate algorithms for evaluation.

[0051] Fig. 3 shows basic representations of the piston position and the piston force in a case with brake wear.

[0052] As can already be seen in the diagrams in Fig. 2, an idle stroke LH is carried out up to a piston position of 17 mm and an elastic stroke of 22 mm, i.e. up to a piston position of 39 mm, is carried out. Due to a prolonged braking process, for example during a long downhill ride, the friction elements 5 and / or the element 4 to be braked wear out, so that in order to maintain the necessary braking force it is necessary to carry out an additional wear stroke VH. The wear stroke VH is a stroke that must be traveled by the piston in order to compensate for the wear of the friction material, i.e. the friction elements 5 and the element 4 to be braked, during braking so that the desired braking force is maintained. The wear stroke VH in this example is 3 mm, i.e. up to a piston stroke of 42 mm.To end the braking process, the friction elements 5 are then moved back in the other direction, whereby the piston force is again reduced until the piston position at which the friction elements 5 lift off the element 4 to be braked is reached. Since the elastic stroke EH / -EH of 22 mm is the constant system property, the friction elements 5 lift off the element 4 to be braked at a piston position of 20 mm, which here represents the second corner position. The actuating element 9 then moves back to the rest position, covering 20 mm, namely the 17 mm path of the -LH and the 3 mm path of the -VH. The second corner position therefore differs from the first position in this case by 3 mm, which corresponds to the wear stroke VH and the wear of the element 4 to be braked and the friction elements 5.

[0053] Fig. 4 shows basic representations of the piston position in a case of adjustment after brake wear.

[0054] The representation of the upper bar chart corresponds to that of the upper bar chart in Fig. 3, according to which wear of the element 4 to be braked and of the friction elements 5 occurs during braking. It can also be seen here that the return stroke -LH-VH, i.e. -20 mm, corresponds to the wear corresponding to 3 mm of piston travel, thus not yet compensated. Following this braking process, a next braking process takes place, shown in the lower bar chart, which is basically already shown in Fig. 2. In the lower diagram of Fig. 4, the idle stroke LH is also 17 mm, from which it can be seen that the wear of the last braking process during the idle stroke LH was compensated for the next braking process by the wear adjustment device 8, so that the idle stroke LH corresponds to the usual idle stroke LH of 17 mm. Alternatively, there is also the possibility that the wear adjustment device 8 already compensates for the wear during the

[0055] The wear is compensated during the return stroke -LH-VH, whereby this return idle stroke -LH would then again be 17 mm. Alternatively, there is the possibility that the wear is partially compensated during the return idle stroke -LH and partially during the idle stroke LH during the next braking operation.

[0056] Fig. 5 shows basic representations of the piston position in a case of thermal expansion of the electro-mechanical brake.

[0057] In this illustration, the first part of the braking process, until the currently desired braking effect is achieved, corresponds to the braking processes shown in Figures 3, 4, and 5. First, the idle stroke LH of 17 mm piston stroke is performed, followed by the elastic stroke EH of 22 mm.

[0058] During braking, thermal expansion of the electromechanical brake 2, particularly of the friction element 5 and the element 4 to be braked, occurs due to kinetic energy being converted into heat. Since this expansion leads to an increase in the braking force, the electromechanical brake actuator 6 is controlled to retract its actuator 9 by a so-called expansion stroke AH in order to reduce the braking force to the actually required braking force. The expansion stroke AH is therefore a stroke that the piston must travel to keep the application forces constant due to thermal expansion. In this example, the expansion stroke is -7 mm.

[0059] As can be seen from the following bars, the elastic stroke -EH is also 22 mm in this case, an approximately constant system property. The return stroke from the second corner position therefore results from the idle stroke -LH, which is reduced by the extension stroke AH. However, this extension stroke AH is not compensated for; rather, cooling of the components of electromechanical brake 2 restores the original state, so that the idle stroke LH shown in the lower bar chart is again 17 mm during the next braking operation.

[0060] During operation, a method for detecting the state of the electromechanical brake is carried out as described below. According to the diagrams shown in Figures 2 to

[0061] 5, the active element 9 of the electro-mechanical brake actuator

[0062] 6 is moved in a direction in which the friction element 5 connected to the active member 9 is moved in an active direction towards the element 4 to be braked. A position of the active member 9 in which a contact of the friction element 5 with the element 4 to be braked is detected by an initial increase in force on the active member 9 is detected as the first corner position, and the movement of the friction element 5 is continued in the active direction to generate the braking process. To end the braking process, the friction element 5 is moved counter to the active direction. This also reduces the force on the active member 9, and a position of the active member 9 in which a lifting of the friction element 5 from the element 4 to be braked is detected by an end of a drop in force on the active member is detected as the second corner position. The state of the electromechanical brake can be detected using these two corner positions.

[0063] By calculating the position difference of the active element 9 at the first corner position and the second corner position, the wear of the friction elements 5 and the element 4 to be braked can be determined. If there is no position difference between the first corner position and the second corner position, it can be seen that no noticeable wear occurred during the last braking operation.

[0064] In addition to determining wear during a single braking operation, it is also possible to determine total wear by summing the wear of the friction elements 5 and the element 4 to be braked. To determine the total wear as accurately as possible, it is determined after each braking operation. In alternative embodiments, this total wear is determined after a predetermined number of braking operations or, for example, after a predetermined period of time has elapsed.

[0065] If the wear of the friction elements 5 and the element 4 to be braked exceeds a predetermined limit, the wear is automatically compensated by the wear adjustment device 8. In the present embodiment, this is done via an automatic mechanical control of the wear adjustment device 8 within the brake mechanism 7. In alternative embodiments, this control can also be pneumatic, or the determination of the wear of the friction elements 5 and the element 4 to be braked by means of the first and second corner positions is used to control the wear adjustment device to compensate for the wear.

[0066] This compensation can, as already described above, take place during the return stroke of the friction elements 5 lifted from the element 4 to be braked, or during the idle stroke LH of the friction elements 5 to the element 4 to be braked during the next braking operation. Furthermore, it is also possible for the compensation to take place partly during the return stroke -LH and partly during the idle stroke LH of the subsequent braking operation. Alternatively, compensation may not take place immediately, but rather during one or more of the next braking operations, as long as it is ensured that wear does not lead to a functional impairment.

[0067] A path of the active member 9 from the rest position of the active member 9 to the first corner position corresponds to a corresponding distance of the friction elements 5 from the element 4 to be braked, wherein the wear is compensated such that the distance is within a predetermined tolerance range. In alternative embodiments, no reference is made to the predetermined tolerance range, but rather the wear is always compensated by a fixed amount. If the wear is compensated such that the distance is within the predetermined tolerance range, it is possible to determine a functionality of the wear adjustment device 8 by determining that the corresponding distance is within the predetermined tolerance range after a predetermined number of braking operations, over the path of the active member 9 from the rest position of the active member 9 to the first corner position.Alternatively, it is also possible to determine the functionality of the wear adjustment device 8 only via the first corner position, without determining the wear of the friction element 5 and the element 4 to be braked via the first corner position and second corner position.

[0068] In addition, it is possible to determine a thermal expansion of the friction elements 5 and the element 4 to be braked as a whole by calculating the position difference between the first corner position and the second corner position before and after a braking operation.

[0069] Although the present invention has been described with reference to specific features and embodiments, it is obvious that various modifications and combinations may be made thereto without departing from the spirit and scope of the invention. Accordingly, the description and drawings are to be considered merely as an illustration of the invention as defined by the appended claims and are intended to cover all modifications, variations, combinations, or equivalents that fall within the scope of the present invention.

[0070] LIST OF REFERENCE SYMBOLS

[0071] 1 braking system

[0072] 2 electro-mechanical brake 3 control device

[0073] 4 element to be braked

[0074] 5 Friction element

[0075] 6 electro-mechanical brake actuator

[0076] 7 Brake mechanism 8 Wear adjustment device

[0077] 9 Actuator

[0078] LH, - LH idle stroke EH, - EH elastic stroke

[0079] VH wear stroke

[0080] AH expansion stroke

Claims

PATENT CLAIMS 1 . Method for detecting a state of a brake (2) for a rail vehicle, comprising the steps: Moving an active member (9) of a brake actuator (6) in a direction in which a friction element (5) connected to the active member (9) is moved in an active direction towards an element (4) to be braked; Detecting a position of the active element (9) in which a contact of the friction element (5) with the element (4) to be braked is detected by an incipient increase in force, as the first corner position.

2. Method according to claim 1, wherein a path of the active member (9) from a rest position of the active member (9) to the first corner position corresponds to an associated distance of the friction element (5) from the element (4) to be braked, and wear of the friction element (5) and the element (4) to be braked is compensated such that the associated distance is within a predetermined tolerance range, with the step: Determining a functionality of a wear adjustment device (8) for automatically compensating for wear by determining that the associated distance is within the predetermined tolerance range after a predetermined number of braking operations, via the path of the actuating member (9).

3. Method according to one of the preceding claims, comprising the steps of: continuing the movement of the active member and the associated Friction element (5) in the direction of action to generate a braking process; Moving the active member and the friction element (5) connected thereto in the opposite direction of action to terminate the braking process; Detecting a position of the active element (9) in which a lifting of the friction element (5) from the element to be braked (4) is detected by terminating a force drop, as a second corner position.

4. Method according to claim 3, comprising the step: Determining wear of the friction element (5) and the element to be braked (4) by calculating a position difference between the first corner position and the second corner position.

5. Method according to claim 4, comprising the step: Determining a total wear of the friction element (5) and the element to be braked (4) by summing the wear of the friction element (5) and the element to be braked (4) after several braking operations.

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

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

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

9. Method according to one of claims 3 to 8, comprising the step: Determining a thermal expansion of the friction element (5) and the element to be braked (4) by calculating the position difference between the first corner position and the second corner position.

10. Brake (2) for a rail vehicle, comprising: a brake actuator (6), a friction element (5), an element to be braked (4), and a brake mechanism (7) which has the brake actuator (6) and which is designed to actuate the brake in dependence on a movement of an active element (9) of the Brake actuator (6) to move the friction element (5) for a braking operation in an effective direction towards the element (4) to be braked and to end the braking operation to move the friction element (5) away from the element (4) to be braked opposite to the effective direction, wherein the brake mechanism (7) is designed to detect a force exerted on the friction element (5) along the effective direction and a position of the friction element (5) along the effective direction by means of a force exerted on an effective member (9) of the brake mechanism (7) and a position of the effective member (9).

11. Brake (2) according to claim 10, wherein the brake (2) is designed to carry out a method according to one of claims 1 to 9.

12. Brake (2) according to claim 11, wherein the brake mechanism (7) has a wear adjustment device (8), and the brake (2) is designed to carry out a method according to one of the preceding claims with the features of claim 2.

13. Braking system (1), comprising: a brake (2) according to one of claims 10 to 12, and a control device (3) which is designed to control the brake (2), wherein the control device (3) is designed to evaluate and process the detected first corner position and second corner position. REVISED SHEET (RULE 91) ISA / EP

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