Grounding contact and method for operating a railway vehicle

Abstract

The invention relates to a method for operating a rail vehicle having a grounding contact (20), to a grounding contact and to a monitoring system, wherein the rail vehicle has the grounding contact on a wheelset with an axle and wheels, wherein the grounding contact has a housing unit (22), a contact device (26) and a sensor device (61), wherein the contact device has a contact piece (28) arranged on a contact surface of an axle, wherein an electrical sliding contact is formed between the contact surface and the contact piece, wherein the grounding contact comprises a measuring unit having a measuring device (63), wherein at least one sensor (65) of a sensor device (61) of the measuring device is arranged on the contact device and / or adjacent to the contact device, wherein a measured value of the contact device is detected by means of the sensor device, wherein the measured value is processed by means of the processing device (62) of the measuring device, and a characteristic value describing an operating state of the wheelset and / or a rail is determined.

Description

[0001] The invention relates to an earthing contact and a method for operating a rail vehicle, wherein the rail vehicle has an earthing contact on a wheelset with an axle and wheels, wherein the earthing contact is formed with a housing unit, a contact device and a sensor device, wherein the contact device has a contact piece arranged on a contact surface of an axle, wherein an electrical sliding contact is formed between the contact surface and the contact piece.

[0002] Such grounding contacts and methods are well known from the prior art and are regularly used on axles of railway vehicles, particularly electrically powered railway vehicles. Grounding contacts serve to transmit electrical currents via an axle of a wheelset to a rail. The known grounding contacts can be arranged on an axial side of an axle and be rotationally fixed to an axle bracket of the railway vehicle or rotatably connected to it relative to the axial side. The grounding contact comprises a housing with an axially arranged, flange-like housing cover, wherein graphite contact elements inside the housing are contacted with the axle or corresponding slip rings or grinding wheels for the transmission of a current. It is also known to attach a sensor device or a flange-like sensor housing to the housing cover.The housing cover has an opening through which, for example, a rotary encoder of the sensor device can detect signals generated by axle rotation. These signals are transmitted via a cable to a vehicle control unit, which uses them to generate axle speed, pulses for engine control, or a braking system. The sensor thus transmits a signal to a vehicle control unit, which processes the signal for control purposes. Such a grounding contact is known, for example, from EP 2 423 068 A1. Another grounding contact with a sensor device designed to detect rotational speed can be found in EP 0 958 984 A1. To increase reliability, the sensors can be monitored so that a sensor failure can be detected as quickly as possible.

[0003] Since the contact pieces of the grounding contact are always in contact with the axle or rotating components of the axle, they wear down due to abrasive wear of the material or graphite of the contact pieces. It is therefore necessary to regularly maintain grounding contacts to ensure their proper function. This maintenance is always carried out at a rail vehicle depot as part of a scheduled service interval, requiring partial disassembly of the housing unit to inspect the contact pieces. This allows for the replacement of any contact pieces that are not yet completely worn. Overall, this results in increased effort for the maintenance of grounding contacts and the replacement of contact pieces.

[0004] The invention is therefore based on the objective of proposing a method for operating a rail vehicle as well as an earthing contact and a monitoring system with an earthing contact that enables improved operation.

[0005] This problem is solved by a method having the features of claim 1, an earthing contact having the features of claim 15 and a monitoring system having the features of claim 16.

[0006] In the inventive method for operating a rail vehicle, the rail vehicle is equipped with at least one grounding contact on a wheelset with an axle and wheels, wherein the grounding contact is formed with a housing unit, a contact device and a sensor device, wherein the contact device has a contact piece arranged on a contact surface of an axle, wherein an electrical sliding contact is formed between the contact surface and the contact piece, wherein the grounding contact comprises a measuring unit with a measuring device, wherein at least one sensor of a sensor device of the measuring device is arranged on the contact device and / or adjacent to the contact device, wherein a measured value of the contact device is detected by means of the sensor device.wherein the measured value is processed by means of a processing unit of the measuring device and a characteristic value describing an operating state of the wheelset and / or a running rail is determined.

[0007] The grounding contact is located on the wheelset, which can be a running wheelset, a driving wheelset, or a loose wheelset with one or more axles. The axle(s) of the wheelset each have two wheels that rest on and roll on a running rail of the rail vehicle. The grounding contact is located on the axle and, within the housing unit, includes the contact device with at least one contact piece. The contact device serves to hold and electrically connect the contact piece. The axle or a component located on the axle forms the contact surface of the axle, which is rotatable relative to the contact piece. The axle can be contacted radially or axially by the contact piece. Furthermore, the contact device can comprise multiple contact pieces. The contact piece can be made of graphite.

[0008] In the method according to the invention, the grounding contact comprises a measuring unit with a measuring device, which in turn includes a sensor assembly with at least one sensor. The sensor is arranged on and / or adjacent to the contact device, or preferably in close proximity to the contact device or contact piece. A measured value of the contact device or contact piece is acquired by means of the sensor assembly or the sensor. This measured value is a physical quantity that is directly related to the contact device and changes during operation of the grounding contact. The measured value or quantity is then processed by the processing unit, and a characteristic value is determined that is suitable for describing an operating state of the grounding contact and / or the rail.The characteristic value can be a parameterized value, a characteristic parameter, a key figure, or a data set. The characteristic value can also be contained within a data set. In particular, the measured values ​​are to be digitally processed by the processing device in order to obtain a characteristic value that can be further processed digitally. The processing device is therefore comprised of at least one digital electronic circuit capable of processing analog and / or digital signals from the sensor. The processing device can, for example, also be a programmable logic controller (PLC), an integrated circuit (IC), or a computer.

[0009] Because the processing unit determines the characteristic value suitable for describing the operating state of the grounding contact, it becomes possible to determine or monitor the operating state of the grounding contact, the wheelset, and / or the running rail. Since the operating state of the grounding contact is also significantly dependent on the condition or operating state of the wheelset and / or the running rail, the characteristic value can also describe the operating state of the wheelset and the running rail. For example, the operating state could be a state of wear, making it possible to make a statement about the wear state based on the characteristic value. Overall, this allows for more targeted maintenance of the grounding contact, the wheelset, and the running rail without having to adhere to regular maintenance intervals. In short, this makes it possible to monitor a grounding contact, a wheelset, or...One track is more cost-effective, and therefore a rail vehicle is more economical to operate overall.

[0010] Thus, a measured value such as axle rotation, acceleration, frequency, temperature, humidity, force, current, voltage, distance, mass, and / or position can be continuously or discontinuously recorded and processed. The axle rotation can be used to measure the speed or distance traveled by the rail vehicle. For this purpose, a rotary encoder on the axle or another suitable sensor can be used. Temperature can be measured with a temperature sensor at the grounding contact or directly on the housing unit or contact device, allowing, for example, the detection of potential overheating of an axle bearing. Force can be determined using a strain gauge, force sensor, pressure sensor, or similar device. For example, the contact force of the contact piece can then be measured. Current or...Voltage can be measured using an ammeter or voltmeter as a sensor. For example, a current diverted through the grounding contact can then be determined. The position of the grounding contact can be easily determined using a satellite navigation system, such as GPS. The measured value(s) can be continuously acquired and processed. It is also possible to acquire and process the measured value(s) discontinuously, for example, at set times or on specific occasions.

[0011] It is particularly advantageous if at least one accelerometer is used as the sensor, which can then be arranged on the contact device, preferably on the contact piece. The accelerometer or vibration sensor can be used to measure a natural frequency and / or resonance frequency of the contact piece or the entire grounding contact. For example, movement of the contact piece on the axle can be detected by means of the accelerometer, whereby conclusions can then be drawn from the movement about the shape of the guide rail or a flat spot on a wheel rim. In this way, for example, an unevenness in the guide rail can be easily determined. Special test runs or on-site inspections of the guide rail to determine such defects are then no longer necessary. Furthermore, a change in the contact piece due to wear orWear on the axle causes a change in the natural frequency and / or resonance frequency of the contact piece. This can result in a difference between a new and a worn contact piece. Since the contact piece is in regular contact with the axle during the movement of the rail vehicle, the processing device can deduce a change in the contact piece from a change in its natural frequency and / or resonance frequency. For example, the processing device could store natural frequencies and / or resonance frequencies of new and worn contact pieces, allowing it to perform a comparison and determine the wear condition or consumption of the contact piece without further calculations. This wear can then be output as a characteristic value. Furthermore, damage to the contact piece can be easily detected.

[0012] The processing unit can acquire and store sensor readings and / or characteristic values ​​at regular intervals, upon change, or continuously. Accordingly, it can be configured to acquire and store readings and / or characteristic values ​​only when they change, in order to minimize the amount of data. Alternatively, continuous acquisition and storage is possible. Storing the readings and / or characteristic values ​​allows for processing even after acquisition. For example, readings can be acquired during a train journey, while the determination of the characteristic values ​​can only be carried out during maintenance of the train in a depot. For instance, the condition of a rail along a train's route can be determined in this way after a journey.

[0013] The measuring device can transmit the measured values ​​and / or characteristic values ​​to an evaluation unit, whereby the measured values ​​and / or characteristic values ​​can be stored in a database of the evaluation unit and / or further processed by means of an evaluation device of the evaluation unit. The evaluation unit can therefore comprise the database and the evaluation device. The evaluation unit can thus serve to collect and further process the measured values ​​and / or characteristic values ​​and can be a computer. For example, the evaluation device can display or output the result of an evaluation to an operator. The evaluation unit can have a range of functions that extends beyond the range of functions of the processing device. In principle, however, it is also possible to integrate the processing device into the evaluation unit and vice versa.In principle, such an evaluation unit can also exist independently of the grounding contact as a component of the rail vehicle.

[0014] A transmission device within the measuring instrument allows the measured values ​​and / or characteristic values ​​of the measuring instrument to be transmitted to the evaluation unit via a data connection. The evaluation unit can be located at a distance from the measuring instrument or integrated within it. If the control device or the evaluation unit is integrated into the measuring instrument, the data connection can be established simply via a cable connection. This also allows parts of the measuring instrument, such as the processing unit, the control device, and the evaluation unit, to be installed elsewhere on the rail vehicle, for example, in a driver's cab. Data exchange, for example, based on a transmission protocol, can take place during the transmission of the measured values ​​and / or characteristic values. The data connection can be established continuously, at regular intervals, or event-driven.Overall, this makes it possible to collect and analyze data gathered by the measuring device. Numerous evaluation options then enable the analysis of specific conditions and events, allowing for the optimization of the operation of the grounding contact, the wheelset, and the running rail or the rail vehicle.

[0015] The data connection can be established via an external data network. This connection can be established via a mobile network, WLAN, a satellite connection, the internet, or any other wireless standard, either alone or in combination. If the evaluation unit is located at a distance from the measuring unit, it can also be positioned outside the rail vehicle, for example, in a building. This makes it possible, in particular, to monitor the function of the grounding contact and the wheelset on the rail vehicle without requiring a person to perform this task on the rail vehicle itself.

[0016] A user unit can establish a data connection to the evaluation unit and / or the measuring unit, allowing the measured values ​​and / or characteristic values ​​to be transmitted to and output by the user unit. The user unit can be a computer independent of the evaluation unit and / or the measuring unit. This computer can be a desktop computer, a mobile device, or similar, enabling a separate data connection for data exchange with the evaluation unit and / or the measuring unit. This data exchange can occur, for example, via an external data network such as the internet. In this way, data processed by the evaluation unit or measured values ​​and / or characteristic values ​​further processed by the evaluation device could be made available to a wider group of users.The evaluation unit can, for example, consist of a server with software that transmits the information contained in the evaluation unit's database to the user unit. This transmission can take the form of providing a web page with selected information, such as the current wear status of the contact piece.

[0017] The processing unit or evaluation system can analyze the temporal profile of measured values ​​and / or characteristic values ​​and determine the wear state of the contact piece, wheelset, and / or rail, taking into account a time-dependent component relevant to wear and / or a measurement-dependent component. This allows not only for an assessment of the current wear state but also for an approximate determination of when, for example, a contact piece or wheel is likely to become worn. This makes it possible to precisely define and optimize the maintenance interval for the grounding contact or other components of the wheelset. Furthermore, the temporal profile can also reveal when specific events occurred. If events occur repeatedly, a pattern can be derived.For example, when traveling along a particular section of track, a poorer condition of a rail or increased wear and tear may be observed.

[0018] The sensor device can detect vibrations of the contact piece, and the processing unit can determine a natural frequency and / or a resonance frequency of the contact piece and / or the axle. The processing unit or the evaluation unit can determine the wear state of the contact piece, the wheelset, and / or the rail. When the contact piece wears, its shape, in particular its height, can change, and this change in shape can alter the natural frequency and / or the resonance frequency of the contact piece. The processing unit can determine the degree of wear of the contact piece and / or the axle from the natural frequency and / or the resonance frequency. If the natural frequency and / or the resonance frequency decreases with increasing carbon abrasion of the contact piece, the processing unit can determine the wear level of the contact piece and / or the axle.If a component of the axle changes, this change can provide information about the degree of wear of the contact piece and / or the axle. This allows not only the determination of whether the contact piece is new or completely worn, but also the extent to which the contact piece is worn.

[0019] The processing unit or evaluation unit can perform a pattern analysis of the measured values ​​and / or characteristic values ​​stored over a period of time and derive a key figure from this analysis. It may also be possible to perform the pattern analysis using artificial intelligence. The processing unit or evaluation unit can relate the measured values ​​from different sensors and / or characteristic values ​​to each other and derive functional dependencies between them. This allows for the investigation of functional dependencies between the sensors. For example, vibrations or oscillations can be correlated with temperature, potentially revealing that an axle bearing is damaged. A range of other operating states and events resulting from functional dependencies can also be detected and interpreted, such as the load status of the rail vehicle.the respective carriages, gradients and curves of the running track, wear of the contact piece as a result of mechanical friction on the axle or its components, sections of a running track with particularly uneven running characteristics of the axle and thus with particularly high or particularly low wear, a wear rate depending on driving behavior, such as acceleration or standstill of the rail vehicle, damage to components of the wheelset, the axle, the wheels, bearings and the contact device, current leakage via the grounding contact and resulting faults in components, a condition of wear components of the wheelset, such as bearings, joints, structural elements, a loss of components, for example as a result of an impact on an obstacle, as well as a position, speed, acceleration and direction of travel of the rail vehicle.These previously mentioned conditions and events can be addressed through maintenance measures, adjustments to the driving behavior of the rail vehicle, or other suitable measures.

[0020] It may also be provided that the processing device or evaluation unit relates signals or measured values ​​from sensors and / or characteristic values ​​not associated with the grounding contact to signals or measured values ​​from sensors and / or characteristic values ​​associated with the grounding contact. For example, by additionally considering signals or measured values ​​and / or characteristic values ​​from sensors of a current collector for a conductor rail, a roof-mounted current collector, a flange lubrication system, a shaft grounding system, etc.

[0021] A position sensor in the sensor system can determine the location of the grounding contact. This location can then be assigned to specific parameters, allowing the evaluation unit to determine the wear condition of the rail. For example, the position sensor can use satellite navigation to determine the position of the grounding contact and thus the vehicle. This allows, among other things, the identification of the point along a track where a specific measurement from another sensor in the sensor system was recorded. This enables the assignment of the corresponding location to an event or measurement. Furthermore, the evaluation unit can determine the wear condition of the rail, for example, by analyzing vibrations transmitted from the wheels to the contact device or contact piece along the rail.The contact device may exhibit altered vibration behavior if the guide rail is heavily worn. Furthermore, steps, unevenness, and curves on the guide rail can be detected and assigned to a specific location along the track. This allows for influencing the speed of the rail vehicle in these localized sections of the track.

[0022] The evaluation unit can process characteristic values ​​from measuring units of multiple grounding contacts. This allows the evaluation unit to process characteristic values ​​from several grounding contacts located on a single rail vehicle or wheelset. By comparing the characteristic values ​​of the grounding contacts, the accuracy of a measurement or monitoring can be further increased. Furthermore, the evaluation unit can process characteristic values ​​from grounding contacts located on different rail vehicles.

[0023] This also significantly improves the accuracy of measurements and monitoring of rail vehicles and their respective tracks. Among other things, it allows for the acquisition of a current and constantly changing picture of the condition of a rail network and the rail vehicles operating on it. The resulting optimization of operational conditions can substantially reduce operating costs. Furthermore, regular and frequent inspections of the infrastructure and rail vehicles are no longer entirely necessary, and vehicle safety during operation is significantly increased. The need for special test runs can also be eliminated.

[0024] The grounding contact according to the invention for an axle of a wheelset of a rail vehicle is designed with a housing unit, a contact device and a sensor device, wherein the contact device has a contact piece arranged on a contact surface of the axle, wherein an electrical sliding contact can be formed between the contact surface and the contact piece, wherein the grounding contact comprises a measuring unit with a measuring device, wherein at least one sensor of a sensor device of the measuring device is arranged on the contact device and / or adjacent to the contact device, wherein a measured value of the contact device can be detected by means of the sensor device, wherein the measured value can be processed by means of a processing device of the measuring device and a characteristic value describing an operating state of the wheelset and / or a ticket can be determined.Regarding the advantages of the grounding contact according to the invention, reference is made to the description of advantages of the method according to the invention. The housing unit can be formed from a housing body and a housing cover. Further advantageous embodiments of a grounding contact will become apparent from the descriptions of features in the dependent claims relating to claim 1 of the method.

[0025] The monitoring system according to the invention comprises at least one rail vehicle with at least one grounding contact according to the invention.

[0026] The monitoring system can comprise multiple measuring units and an evaluation unit for processing measured values ​​and / or characteristic values ​​from the measuring units of several grounding contacts. As previously described, this makes it possible to monitor multiple grounding contacts of a rail vehicle or multiple rail vehicles with grounding contacts using a single evaluation unit.

[0027] The monitoring system can therefore include multiple rail vehicles, each with at least one grounding contact. It is also possible for the rail vehicles to each have multiple grounding contacts.

[0028] Further advantageous embodiments of a monitoring system result from the feature descriptions of the dependent claims relating back to method claim 1.

[0029] The invention will now be explained in more detail with reference to the accompanying drawings.

[0030] They show: Fig. 1 a first embodiment of an earthing contact on a rail vehicle in a side view; Fig. 2 a second embodiment of an earthing contact on a rail vehicle in a sectional view; Fig. 3 a schematic representation of an embodiment of a measuring unit; Fig. 4 A schematic representation of a monitoring system.

[0031] The Fig. 1 Figure 1 shows an earthing contact 10 on an axle 11 of a rail vehicle 12, which is only partially shown here. The axle 11 has two wheels 13, each of which can roll on a running rail 14. A bearing device 16 for the rotatable mounting of the axle 11 is arranged at one axial end 15 of the axle 11. The axle 11 is connected to the frame 18 of a wheelset 19 of the rail vehicle 12 via a damping device 17 at the bearing device 16. The earthing contact 10 is flanged to the bearing device 16.

[0032] The Fig 2 Figure 1 shows a sectional view of an earthing contact 20 on an axle of a rail vehicle (not shown in detail here). An axial end cap 21 of the axle is indicated by a dashed line. For the sake of simplicity, a bearing block of the axle, to which the earthing contact 20 is screwed, is also omitted. The earthing contact 20 comprises a housing unit 22, which consists solely of a housing body 23 and a housing cover 24. Furthermore, a contact device 26 of the earthing contact 20 is formed here from a contact disc 27 and contact pieces 28, which are essentially made of graphite. The contact pieces 28 are held in a contact piece holder 29 and are each pressed against the contact disc 27 by a spring device 30 to form an electrical sliding contact.The contact pieces 28 are further electrically connected to the contact piece holder 29 by means of strands 31, wherein a connecting piece 32 is connected to the contact piece holder 29 with a cable 33, which electrically connects the earthing contact 20 to a motor as is generally known.

[0033] A sensor device 61, comprising an accelerometer (not shown in detail), is arranged within the housing cover 24. The accelerometer, or another suitable sensor, can be arranged on the housing unit 22, the contact device 26, or the grounding contact 20. Signals acquired by the accelerometer are further processed by a processing unit 62 or a measuring device 63 within the housing cover 24 and transmitted via a transmission device 64 to an external network (not shown). The sensor device 61 also includes a temperature sensor 65, which is arranged on the housing body 23.

[0034] The Fig. 3 Figure 3 is a schematic representation of an embodiment of a measuring unit 34. The measuring unit 34 consists of a measuring device 35 and further comprises an evaluation unit 36. The measuring device 35, in turn, comprises a sensor assembly 37 with a plurality of sensors 38 and a processing unit 39. Furthermore, a power supply unit 40 is provided by means of which the measuring device 35 is supplied with electrical energy. The power supply unit 40 can be an energy storage device, a generator, or an external power supply, for example, via a rail vehicle or a diverted current. The evaluation unit 36 ​​has a database 41 and an evaluation device 42 and receives data or measured values ​​and / or characteristic values ​​from the processing unit 39. The processing unit 39 receives measured values ​​from the sensor 38 of the sensor assembly 37 and processes them. The measured values ​​relate to operating parameters or...physical measured quantities of a contact device of an earthing contact not shown here in the manner described in the . Fig. 1 und 2 The earthing contacts are shown as examples. The processing unit 39 processes the measured values ​​in such a way that a characteristic value describing an operating state of the respective current collector and / or busbar is determined. The characteristic values ​​determined in each case are continuously or successively transmitted from the processing unit 39 to the evaluation unit 36 ​​and stored there in the database 41 or further processed or prepared by the evaluation device 42.

[0035] The Fig. 4 Figure 47 shows a monitoring system 47 with a measuring unit 48. The monitoring system 47 can have multiple measuring units 48. The measuring unit 48 differs from the measuring unit shown in Figure 48. Fig. 3A measuring device 49 is provided, which includes a transmission device 50. The transmission device 50 receives data, specifically measured values ​​and / or characteristic values, from the processing device 39. Furthermore, a data connection 52 exists between the transmission device 50 and an external data network 51, via which measured values ​​and / or characteristic values ​​are transmitted using radio signals. An evaluation unit 54, comprising a database 55 and an evaluation device 56, is connected to the external data network 51 via another data connection 53 and exchanges data, specifically measured values ​​and / or characteristic values, with the transmission device 50 via the external data network 51. In principle, it is also possible to exchange this data directly via a direct data connection 52, bypassing the external data network 51. In addition, a user unit 58 is provided, which is connected to the external data network 51 via another data connection 59.The user unit 59 can thus exchange data with the evaluation unit 54; that is, data from the measuring units 48 processed by the evaluation unit 54 can be output or displayed via the user unit 58 and made available for further use. The user unit 58 can also be directly connected to the evaluation unit 54 via a direct data connection 60. Overall, this makes it possible to acquire measured values ​​via sensors 38 attached to grounding contacts (not shown here) and to transfer these directly to the evaluation unit 54 for storage and evaluation via the external data network 51, for example, the internet. Functional relationships within the data can thus be used, evaluated, and interpreted. The results of these evaluations can be made available to an end user via the user unit 58.

Claims

1. A method for operating a rail vehicle (12), the rail vehicle having a ground contact (10, 20) on a wheel set (19) having an axle (11) and wheels (13), the ground contact having a housing unit (22), a contact device (26) and a sensing device (37, 61), the contact device having a contact piece (28) which is disposed on a contact surface of an axle, an electrical sliding contact being formed between the contact surface and the contact piece, characterized in that the ground contact comprises a measuring unit (34, 48) having a measuring device (49, 63), the measuring device having the sensing device, at least one sensor (38, 65) of the sensing device (37, 61) of the measuring device being disposed on the contact device and / or adjacent to the contact device, a measured value of the contact device being registered by means of the sensing device, the measured value being processed by means of a processing unit (39, 62) of the measuring device and a parameter describing an operating state of the wheel set, a rail (14) and / or the ground contact (10, 20) being determined.

2. The method according to claim 1, characterized in that as a measured value, a speed, an acceleration, a frequency, a temperature, an air humidity, a force, a current, a voltage, a distance, a mass and / or a location is registered and processed continuously or discontinuously.

3. The method according to claim 1 or 2, characterized in that as a sensor (38, 65), at least one acceleration sensor is used, which is disposed on the contact device (26), preferably on the contact piece (28).

4. The method according to any one of the preceding claims, characterized in that the processing unit (39, 62) registers and stores the measured values of sensors (38, 65) and / or the parameters at regular time intervals or, when a change occurs, continuously.

5. The method according to any one of the preceding claims, characterized in that the measuring device (49, 63) transmits the measured values and / or parameters to an evaluation unit (36, 54), the measured values and / or parameters being stored in a database (41, 55) of the evaluation unit and / or being processed by means of an evaluation device (42, 56) of the evaluation unit.

6. The method according to claim 5, characterized in that the measured values and / or parameters of the measuring device (49, 63) are transmitted to the evaluation unit (36, 54) via a data link (52, 53, 57, 60) by means of a transmitting unit (50, 64) of the measuring device (49, 63), the evaluation unit being disposed at a distance to the measuring unit (34, 48) or being integrated in the measuring unit.

7. The method according to claim 6, characterized in that the data link (52, 53, 57, 60) is formed via an external data network (51).

8. The method according to any one of the claims 5 to 7, characterized in that a data link (52, 53, 57, 60) to the evaluation unit (36, 54) and / or to the measuring unit (34, 48) is formed by means of a user unit (58), the measured values and / or parameters being transmitted and output to the user unit.

9. The method according to any one of the claims 5 to 8, characterized in that the processing unit (39, 62) or the evaluation unit (36, 54) evaluates a time curve of the measured values and / or parameters and determines a state of wear of the contact piece (28), the wheel set (19) and / or the rail (14), taking into account a time-dependent component and / or a component depending on measured variables relevant for the wear.

10. The method according to any one of the claims 5 to 9, characterized in that a vibration of the contact piece (28) is registered by means of the sensing device (37, 61), the processing unit (39, 62) determining an eigen-frequency and / or a resonant frequency of the contact piece and / or the axle (11), the processing unit or the evaluation unit (36, 54) determining a state of wear of the contact piece, the wheel set (19) and / or the rail.

11. The method according to any one of the claims 5 to 10, characterized in that the processing unit (39, 62) or the evaluation unit (36, 54) carries out a pattern analysis of the measured values and / or parameters stored over a time period and derives a key figure from the pattern analysis.

12. The method according to any one of the claims 5 to 11, characterized in that the processing unit (39, 62) or the evaluation unit (36, 54) correlates the measured values of different sensors (38, 65) and / or parameters and derives functional dependencies of the measured values and / or parameters.

13. The method according to any one of the claims 5 to 12, characterized in that a location of the ground contacts (10, 20) is determined by means of a position sensor of the sensing device (37, 61), the location being associated to the parameters, the evaluation unit (36, 54) determining a state of wear of the rail (14).

14. The method according to any one of the preceding claims, characterized in that the evaluation unit (36, 54) processes parameters of measuring units (34, 48) of a plurality of ground contacts (10, 20).

15. A ground contact (10, 20) for an axle (11) of a wheel set (19) of a rail vehicle (12), the ground contact having a housing unit (22), a contact device (26) and a sensing device (37, 61), the contact device having a contact piece (28) which is disposed on a contact surface of the axle, an electrical sliding contact being formable between the contact surface and the contact piece, characterized in that the ground contact comprises a measuring unit (34, 48) having a measuring device (49, 63), the measuring device having the sensing device, and at least one sensor (38, 65) of the sensing device (37, 61) of the measuring device being disposed on the contact device and / or adjacent to the contact device, a measured value of the contact device being registerable by means of the sensing device, the measured value being processable by means of a processing unit (39, 62) of the measuring device and a parameter describing an operating state of the wheel set, a rail (14) and / or the ground contact (10, 20) being determinable.

16. A monitoring system (47) having at least one rail vehicle (12) having at least one ground contact (10, 20) according to claim 15.

17. The monitoring system according to claim 16, characterized in that the monitoring system (47) comprises a plurality of measuring units (38, 48) and an evaluation unit (36, 54) for processing measured values and / or parameters of the measuring units of a plurality of ground contacts (10, 20).

18. The monitoring system according to claim 16 or 17, characterized in that the monitoring system (47) comprises a plurality of rail vehicles (12), each having at least one ground contact (10, 20).

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