Pneumatic actuator of a rail vehicle brake and method for detecting damage to a pneumatic actuator

Abstract

A pneumatic actuator of a rail vehicle brake comprises: an actuator housing (21); a brake piston (3) which is disposed in the actuator housing (21) and is coupled to an actuating tappet (4) and to a restoring spring (9), the brake piston (3) being movable from a release position into a brake application position as a result of feeding of compressed air into a service brake chamber (23) and being movable back into the release position by means of the restoring spring (7) as a result of venting; a position detection device (5) coupled to an inner mechanism of the actuator; a pressure sensor (6) for sensing the air pressure in the service brake chamber (23); an evaluation unit (8) connected to the position detection device (5) and to the pressure sensor (6), the position detection device (5) being designed to sense the release position of the brake piston (3), and the evaluation unit (8) being designed to sense, over a multitude of braking processes, a reaction time (t) between the reaching of a predefined air pressure (p) and the reaching of the release position of the brake piston (3) after brake application and to store and compare said reaction times. A method for detecting damage to a pneumatic actuator of a rail vehicle brake is also described.

Description

[0001] Pneumatic actuator of a rail vehicle brake and method for damage detection of a pneumatic actuator

[0002] DESCRIPTION

[0003] The present invention relates to a pneumatic actuator of a rail vehicle brake according to the preamble of claim 1.

[0004] The invention further relates to a method for detecting damage to a pneumatic actuator of such a rail vehicle brake.

[0005] Pneumatic actuators are safety-relevant components of rail vehicle brakes, as they provide the force required for a braking process, for example, with which brake pads attached to brake calipers are pressed against a brake disc.

[0006] It is therefore important to regularly check such pneumatic actuators for damage. This is usually done by conducting regular test disassemblies at predetermined overhaul intervals.

[0007] However, such sample decompositions can only provide an overview of the state of individual actuators. These findings based on individual sample decompositions must then be used to infer the state of other actuators.

[0008] Individual predictions for individual actuators are therefore not possible, so a certain degree of safety must always be taken into account to prevent individual actuators from failing prematurely.

[0009] In addition, the assessment of such findings based on sample dissections requires a great deal of experience from the specialist personnel carrying out the findings.

[0010] It would be desirable to replace the costly and resource-intensive preventive maintenance of such actuators described above with a condition- or function-dependent overhaul. However, since the pneumatic actuators known from the state of the art generally do not have force sensors, direct measurement and assessment of the condition of the individual actuators is not possible.

[0011] Actuators with simple sensors or switches are known, which are used to monitor the actuator, for example by detecting the released state of a brake.

[0012] The object of the present invention is therefore to provide a pneumatic actuator for rail vehicle brakes which enables the simplest possible early detection of damage without disassembling the actuator.

[0013] This object is achieved by a pneumatic actuator of a rail vehicle brake having the features of claim 1.

[0014] The object is further achieved by a method for damage detection of a pneumatic actuator of a rail vehicle brake having the features of claim 6.

[0015] The pneumatic actuator according to the invention comprises an actuator housing and a brake piston arranged in the actuator housing, which is coupled to an actuating plunger and a return spring.

[0016] The brake piston can be moved from a release position to an application position by applying compressed air to a service brake chamber and can be moved back to the release position by venting it using the return spring.

[0017] The pneumatic actuator further comprises a position detection device coupled to an internal mechanism of the actuator and a pressure sensor for detecting the air pressure in the service brake chamber, as well as an evaluation unit connected to the position detection device and the pressure sensor.

[0018] The position detection device is configured to detect the release position of the brake piston. The evaluation unit is configured to record, store, and compare a reaction time between reaching a predetermined air pressure and reaching the release position of the brake piston over a plurality of braking operations after application of the brake. The storage and comparison can be performed both on the vehicle side via the evaluation unit and on the track side via a storage and comparison unit wirelessly connected to the evaluation unit.

[0019] With a pneumatic actuator designed in this way, it is possible to easily detect damage to the actuator by evaluating a braking history stored in the evaluation unit, since the return time after braking from the braking position back to the release position is extended as soon as damage or wear occurs on the pneumatic actuator, which is noticeable by an extended return time.

[0020] Another advantage is that, despite a tolerance of components in each individual actuator, with the result that the position in different actuators is not always identical, the time required by the respective brake piston of a pneumatic actuator to return to its release position is not compared with a predetermined absolute value, but with the value of the respective individual pneumatic actuator in its new state.

[0021] Since the positions of the respective components of an individual pneumatic actuator do not change, this response time can be used as a baseline measure. As soon as damage occurs to the individual pneumatic actuator, this response time will increase, so this increased response time can be used as an indicator of actuator damage.

[0022] Advantageous embodiments are the subject of the subclaims.

[0023] According to an advantageous embodiment, the position detection device comprises a switch and a pin coupled to the brake piston, the pin activating the switch when the brake piston reaches the release position. Such a switch and pin are available as cost-effective components and can be easily mounted on the pneumatic actuator.

[0024] According to an advantageous further development, the position detection device is coupled to an actuator housing.

[0025] It is also conceivable, according to a further design variant, to couple the position detection device with the brake piston.

[0026] According to a further design variant, the pressure sensor is arranged in an anti-skid valve or a relay valve of the pneumatic system of the rail vehicle brake.

[0027] The method according to the invention for detecting damage to a pneumatic actuator of a rail vehicle brake comprises the following method steps: a) detecting and storing a predetermined first number of duration values ​​of a movement of the brake piston after the braking operation has been completed, from reaching a predetermined air pressure in the service brake chamber until the release position of the brake piston is reached, b) calculating a first average value of the stored duration values ​​from the predetermined first number of duration values, c) detecting and storing a predetermined second number of duration values ​​of the movement of the brake piston after the braking operation has been completed, from reaching a predetermined air pressure in the service brake chamber until the release position of the brake piston is reached, d) calculating a second average value of the stored duration values ​​from the predetermined second number of duration values,e) comparing the two mean values ​​of the stored duration values, f) issuing a warning message if the second mean value is greater than the first mean value by a predetermined difference.

[0028] In an advantageous development of the method according to the invention, the predetermined air pressure in the service brake chamber for the start of the time measurement is approximately 1000 hPa. In an advantageous development, the first number of duration values ​​corresponds to a number of braking operations carried out over a period of at least one year during normal operation of the rail vehicle.

[0029] By recording duration values ​​over such a period of at least one year, a reliable baseline value for the reaction time is created, whereby the recorded values ​​also reflect seasonal or weather-related changes.

[0030] The second number of duration values ​​preferably corresponds to a number of braking operations carried out over a period of at least one week during normal operation of the rail vehicle.

[0031] This ensures that individual deviations from duration values ​​are not immediately assessed as a damage indicator.

[0032] For calculating the first mean value of the stored duration values ​​in method step b), preferably only duration values ​​of movements of the brake piston related to specific operating events are used.

[0033] Preferably, the specific operational events are brake tests before or at the start of the rail vehicle's journey, where, unlike braking operations along the route, and especially on different routes, more reproducible conditions prevail. Other specific operational events include, for example, holding brakes at stops / stations / stations. Such holding brakes are also highly reproducible and are performed very frequently.

[0034] A preferred embodiment is explained in more detail below with reference to the accompanying drawings. They show:

[0035] Figure 1 is a schematic partially sectioned view of a pneumatic actuator with position detection device,

[0036] Figure 2 is a schematic sectional view of the position detection device and Figure 3 is an exemplary measurement diagram for reaction times of the brake piston over the service life of the pneumatic actuator for several individual pneumatic actuators.

[0037] In the following description of the figures, terms such as top, bottom, left, right, front, rear, etc., refer exclusively to the exemplary representation and position of the actuator, brake piston, service brake chamber, position detection device, and the like chosen in the respective figures. These terms are not to be understood as limiting; i.e., these references may change due to different operating positions or the mirror-symmetrical design, etc.

[0038] In Figure 1, the reference number 2 designates an embodiment variant of a pneumatic actuator of a rail vehicle brake.

[0039] The pneumatic actuator 2 has an actuator housing 21 and a brake piston 3 arranged in the actuator housing 21, which is coupled to an actuating plunger 4 and a return spring 9.

[0040] The brake piston 3 is limited on one side by a service brake chamber 23, which can be moved from a release position to an application position with compressed air via a compressed air valve. For this purpose, the service brake chamber 23 is filled with compressed air.

[0041] Together with the brake piston 3, the actuating plunger 4 is pressed through an opening in the actuator housing 21 against a gear which is preferably connected to brake calipers, at the ends of which brake pads are arranged which, in the applied position, come into contact with a brake disc of the rail vehicle brake.

[0042] After braking, the brake piston 3 is moved back to the release position by venting the service brake chamber 23. To do this, the return spring 7 pushes the brake piston 3 back into the release position.

[0043] As can be further seen in Figure 1, a position detection device 5 is coupled to an internal mechanism of the actuator 2, which is shown in an enlarged view in Figure 2. The position detection device 5 can be coupled, for example, to an actuating device 9 or to the brake piston 3.

[0044] Furthermore, a pressure sensor 6 is provided, which serves to detect the air pressure in the service brake chamber 23. The pressure sensor 6 is preferably arranged in an anti-skid valve or a relay valve of the pneumatic system of the rail vehicle brake.

[0045] The position detection device 5 and the pressure sensor 6 are connected to an evaluation unit 8, preferably via an electrical cable connection or wirelessly.

[0046] The position detection device 5 is designed to detect the release position of the brake piston 3.

[0047] For this purpose, as shown by way of example in Figure 2, the position detection device 5 is designed with a switch 51 and a pin 52 coupled to the brake piston 3.

[0048] The pin 52 activates the switch 51 when the release position of the brake piston 3 is reached. As can be seen in Figure 1 and Figure 2, an actuating web 53 is attached to the pin 52, which engages behind the switch 51 and, when the release position of the brake piston 3 is reached, strikes a switching element 56 and thus activates the switch 51.

[0049] The position detection device 5 can also be designed in another form, for example as a light barrier or the like.

[0050] It is important that the position detection device 5 sends a signal to the evaluation unit 8, which serves as an end signal for time recording.

[0051] The evaluation unit 8 is configured to record, store, and compare a reaction time t between reaching a predetermined air pressure p and reaching the release position of the brake piston 3 over a plurality of braking operations after application of the brake. The storage and comparison can be performed both on the vehicle side via the evaluation unit 8 and on the track side via a storage and comparison unit (not shown) wirelessly connected to the evaluation unit 8.

[0052] A method for detecting damage to a pneumatic actuator of a rail vehicle brake is carried out via this evaluation unit 8 or the storage and comparison unit wirelessly connected to the evaluation unit 8, comprising the following method steps:

[0053] In a method step a), a predetermined first number m of time duration values ​​t of a movement of the brake piston 3 after the braking operation has taken place is first recorded and stored, starting from reaching a predetermined air pressure in the service brake chamber 23 until the release position of the brake piston 3 is reached.

[0054] The release position of the brake piston 3 is achieved by the signal from switch 51.

[0055] In the evaluation unit 8, as method step b), a first mean value Mi of the stored duration values ​​t from the predetermined first number m of duration values ​​t is then calculated.

[0056] This first number m of duration values ​​t preferably lies within a range of braking operations performed over a period of at least one year during normal operation of the rail vehicle, assuming that the durations within this measurement window, without external influences on the pneumatic actuator, are relatively equal in this initial range. Normal operation of the rail vehicle is defined as use of the rail vehicle for approximately 320 to 350 days per year.

[0057] Figure 3 shows an example measurement diagram for reaction times of individual actuators over their respective service life.

[0058] The framed area in Figure 3 indicates a service life range for at least two of the four actuators shown, in which the reaction times increase significantly compared to the previous reaction times. The other two measurement curves only increase noticeably in a region beyond the framed area, so that the service life of the actuators assigned to these measurement curves is significantly longer than the service life of the actuators where the reaction times increase noticeably after fewer braking operations.

[0059] Method step c) relates to the detection and storage of a predetermined second number n2 of time duration values ​​t of the movement of the brake piston 3 after the braking operation has taken place, from reaching a predetermined air pressure in the service brake chamber 23 until the release position of the brake piston 3 is reached.

[0060] This means that after a predetermined number of braking operations, from which a reference value for the reaction time was determined, the duration values ​​after each braking operation are continuously recorded and saved.

[0061] In a further method step d), a second mean value M2 of the stored duration values ​​t is determined from the predetermined second number n2 of duration values ​​t.

[0062] This means that not a single reaction time measurement value is used to indicate damage to the pneumatic actuator, but rather a plurality of measurement values ​​recorded, preferably over a period of at least one week during normal operation of the rail vehicle, are averaged and then compared in a process step e) with the mean value Mi, which represents the reference value.

[0063] If the second mean value M2 is higher than the first mean value Mi by a predetermined difference d, a warning message is issued in a method step f) indicating that the pneumatic actuator is damaged.

[0064] In particular, differences of at least 10% of the mean value Mi are considered as predetermined differences d.

[0065] Instead of recording the measured values ​​during normal operation, i.e. during the travel of the rail vehicle, it is also conceivable according to a preferred embodiment variant to use exclusively duration values ​​t of movements of the brake piston 3 related to specific operating events for calculating the first mean value of the stored duration values ​​in step b).

[0066] The preferred operating events are considered to be the brake tests before or during the start of the rail vehicle's journey, where well-reproducible conditions prevail, for example, where weather-related events during travel on the track that could affect the movement of the brake piston are (at least largely) absent. It is important to reliably detect sharp increases in the curves shown in Figure 3, which indicate actuator damage, during the evaluation.

[0067] Actuator Actuator housing Base Service brake chamber Brake piston Actuating plunger Position detection device Switch Pin Actuating bar Housing Guide holder Switching element Pressure sensor Return spring Evaluation unit Actuator housing

Claims

Claims 1 . Pneumatic actuator (2) of a rail vehicle brake, comprising - an actuator housing (21 ), - a brake piston (3) arranged in the actuator housing (21) which is coupled to an actuating plunger (4) and a return spring (7), - wherein the brake piston (3) can be moved from a release position to an application position by applying compressed air to a service brake chamber (23) and can be moved back to the release position by venting with the aid of the return spring (7), - a position detection device (5) coupled to an internal mechanism of the actuator (2), - a pressure sensor (6) for detecting the air pressure, - one with the position detection device (5) and the pressure sensor (6) connected evaluation unit (8), characterized in that - the position detection device (5) is designed to detect the release position of the brake piston (3), - the evaluation unit (8) is designed to record, store and compare a reaction time (t) between reaching a predetermined air pressure (p) and reaching the release position of the brake piston (3) over a plurality of braking operations after application of the brake.

2. Pneumatic actuator according to claim 1, characterized in that the position detection device (5) has a switch (51) and a pin (52) coupled to the brake piston (3), wherein the pin activates the switch (51) when the release position of the brake piston (3) is reached.

3. Pneumatic actuator according to claim 1 or 2, characterized in that the position detection device (5) is coupled to an actuator housing (9).

4. Pneumatic actuator according to one of the preceding claims, characterized in that the position detection device (5) is coupled to the brake piston (3).

5. Pneumatic actuator according to one of the preceding claims, characterized in that the pressure sensor (6) is arranged in an anti-skid valve or a relay valve of the pneumatic system of the rail vehicle brake.

6. Method for detecting damage to a pneumatic actuator of a rail vehicle brake according to one of the preceding claims, comprising the method steps: - a) detecting and storing a predetermined first number (m) of time duration values ​​(t) of a movement of the brake piston (3) after the braking operation has been carried out, from reaching a predetermined air pressure in the service brake chamber (23) until the release position of the brake piston (3) is reached, - b) calculating a first mean value (Mi) of the stored duration values ​​(t) from the predetermined first number (m) of duration values ​​(t), - c) detecting and storing a predetermined second number (n2) of time duration values ​​(t) of the movement of the brake piston (3) after the braking operation has been completed, from reaching a predetermined air pressure in the service brake chamber (23) until the release position of the brake piston (3) is reached, - d) calculating a second mean value (M2) of the stored duration values ​​(t) from the predetermined second number (n2) of duration values ​​(t), - e) comparing the two mean values ​​(Mi, M2) of the stored duration values ​​(t), - f) issuing a warning message if the second mean value (M2) is greater than the first mean value (Mi) by a predetermined difference (d).

7. Method according to claim 6, characterized in that the predetermined air pressure in the service brake chamber (23) for the start of the time measurement is approximately 1000 hPa.

8. Method according to claim 6 or 7, characterized in that the first number (m) of duration values ​​(t) corresponds to a number of braking operations carried out over a period of at least one year during normal operation of the rail vehicle.

9. Method according to claim 6, 7 or 8, characterized in that the second number (n2) of duration values ​​(t) corresponds to a number of braking operations carried out over a period of at least one week during normal operation of the rail vehicle.

10. Method according to one of claims 6 to 9, characterized in that for calculating the first mean value (Mi) of the stored duration values ​​(t) in step b) only duration values ​​(t) of movements of the brake piston (3) related to specific operating events are used.

11. Method according to claim 10, characterized in that the specific operating events are brake tests before or upon commencement of travel of the rail vehicle and / or holding brakes at stops / stations / stations of the rail vehicle.

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