Inductive wheel sensor for rail traffic

Abstract

The invention relates to an inductive wheel sensor for rail traffic, comprising at least one printed circuit board with at least one sensor coil, wherein the at least one sensor coil has two D-shaped coil regions each with a straight side and a curved side, wherein the D-shaped coil regions of the at least one sensor coil are arranged next to one another in such a way that their straight sides face one another and their curved sides face away from one another, and wherein the two D-shaped coil regions of the at least one sensor coil are arranged in the wheel sensor in such a way that, when the wheel sensor is mounted on a rail as intended, the two D-shaped coil regions each lie in a substantially horizontal plane and their straight sides run transversely to the longitudinal direction of the rail.

Description

[0001] D / PINUXR-039-P2

[0002] - 1 -

[0003] INDUCTIVE WHEEL SENSOR FOR RAIL TRANSPORT

[0004] TECHNICAL AREA OF INVENTION

[0005] 5

[0006] The invention relates to an inductive wheel sensor for rail transport as well as methods for simulating the passage of a wheel of a rail vehicle over an inductive wheel sensor and for calibrating such a wheel sensor.

[0007] BACKGROUND OF THE INVENTION

[0008] Wheel sensors, particularly in the form of inductive wheel sensors, have long been known for use as so-called wheel sensors, e.g., from DE 235 26 089 A1, DE 32 34651 A1, and DE 33 13 805 A1. They comprise at least one sensor element, typically in the form of an AC-powered resonant circuit coil, which responds to relative movement between the sensor element and a metallic object, e.g., a railway wheel rolling past the sensor element, and triggers a pulse. This pulse can be used, for example, for counting or for triggering specific control signals. If the sensor element is an AC-powered resonant circuit coil, also called a sensor or response coil, it is typically connected to a capacitor to form an LC resonant circuit and is located in a quiescent current monitoring circuit.If a metallic object moves through the electromagnetic field of the coil, the electrical behavior of the monitoring circuit changes, so that counting or control pulses can then be generated via appropriate trigger circuits in a manner known per se.

[0009] A typical application of wheel sensors is the monitoring of track sections of a rail system, where wheel sensors arranged at the beginning and end of a track section to be monitored are used to count whether the number of wheels entering the track section (and thus also the corresponding number of axles of a rail vehicle) is correct, which is why in the railway sector a D / PINUXR-039-P2 is not typically used.

[0010] - 2 -

[0011] (Wheel count, but axle count) corresponds to the number of wheels or axles that have left the track section, in order to then report the corresponding track section to a higher-level control system as free or occupied.

[0012] 5

[0013] If a wheel sensor has two sensor elements arranged one behind the other, the direction of travel and possibly even the speed of travel can be determined from the sequence in which the sensor elements respond.

[0014] In recent years, intensive research has been conducted to improve coils, particularly to enhance detection performance. For example, EP 3569467 B1 discloses a coil with a core oriented orthogonally to the direction of wheel movement. This configuration aims to attenuate magnetic interference fields emitted by rail vehicles. The corresponding wheel sensor5 utilizes the different polarities of the induced voltages in the coil sections to achieve compensation.

[0015] EP 3569466 B1 describes a similar approach, but uses an air-core coil instead of a coil with a core. The windings of this coil are arranged in a figure-eight configuration to achieve improved compensation of interference fields. This arrangement allows for precise configuration of the sensor coil's detection direction and focusing of the detection cone.

[0016] EP 3521131 B1 discloses a system for detecting railway wheels that uses a sensor coil and a compensation coil. The compensation coil is arranged to reduce the effects of external magnetic interference fields on the sensor coil. This configuration aims to improve the accuracy of wheel detection by reducing sensitivity to environmental disturbances. 0 D / PINUXR-039-P2

[0017] - 3 -

[0018] BRIEF SUMMARY OF THE INVENTION

[0019] Despite advances in technology, significant technical challenges remain in the development of wheel sensors. These technical challenges include...

[0020] The 5 challenges include, in particular, the following aspects:

[0021] 1. Optimization of the field geometry to improve sensitivity while minimizing susceptibility to external interference fields, especially in critical detection areas such as the swarm area.

[0022] 2. Achieving a more compact design while maintaining or improving performance.

[0023] 3. Development of more flexible options for simulating wheel crossings, in order to enable more efficient testing of wheel sensors, in particular a self-test of wheel sensors already in operation.

[0024] 4. Improve robustness against manufacturing tolerances to ensure more consistent performance across different production batches.

[0025] The term "swarm zone" refers to the particularly critical detection range in which a wheel just enters the detection cone (the field generated by the coils) of a wheel sensor and the wheel (more precisely, the wheel rim) begins to cause a measurable change in the sensor's magnetic field. In this zone, the signal is still weak because only a small part of the wheel is within the sensor's range. If a wheel comes to a stop near or within the swarm zone, the sensor can oscillate, as trains often do not come to a complete standstill but roll slightly back and forth, making the evaluation of the corresponding detection results particularly difficult.

[0026] The present invention is based on the objective of improving the prior art in at least one of the aforementioned aspects and thus the D / PINUXR-039-P2

[0027] - 4 -

[0028] To increase the performance and reliability of wheel sensors in rail transport.

[0029] The task is solved by an inductive wheel sensor with the characteristics of

[0030] Claim 1, a method for simulating a wheel crossing with the features of claim 12, and a method for calibrating an inductive wheel sensor with the features of claim 19. The respective dependent claims relate to advantageous embodiments and further developments. In an embodiment of an inductive wheel sensor for rail vehicles according to the invention, the sensor comprises at least one printed circuit board with at least one sensor coil, wherein the at least one sensor coil has two D-shaped coil sections, each with a flat and a curved side. The D-shaped coil sections of the at least one sensor coil are arranged side by side such that their flat sides face each other and their curved sides point away from each other.The two D-shaped coil sections of the at least one sensor coil are arranged in the wheel sensor such that, in the intended mounting state of the wheel sensor on a rail, they each lie in a substantially horizontal plane, with their straight sides running perpendicular to the longitudinal direction of the rail. The two D-shaped coil sections form a so-called "double-D configuration" and enable an optimized field geometry with a more homogeneous field line distribution perpendicular to the rail, thereby improving coverage of the critical swarm area and increasing detection accuracy.

[0031] In one embodiment, the two D-shaped coil sections of the at least one sensor coil are formed by a continuous conductor track. This simplifies manufacturing and reduces production tolerances, as no separate connections between the coil sections are required. In another embodiment, each D-shaped coil section of the at least one sensor coil comprises two to six, preferably three to five, and more preferably four interconnected individual coils. This represents an optimal compromise between inductance, sensitivity, and compact design. D / PINUXR-039-P2

[0032] - 5 -

[0033] In one embodiment, the at least one sensor coil extends over several layers of the printed circuit board. The individual coils connected in parallel across multiple layers reduce the DC resistance and thereby increase the quality factor of the overall coil system. This allows for a higher number of turns.

[0034] 5. Simultaneously, a more compact design and improved magnetic properties of the sensor. "Quality" (also called "Q-factor") refers to a measure of the losses in a resonant circuit. Higher quality means lower energy losses and therefore improved sensor sensitivity.

[0035] In a further embodiment, the windings of the D-shaped coil sections of the at least one sensor coil are spatially arranged on the multiple layers such that, in the operating state, constructive magnetic coupling between the layers results in a total inductance that is greater than the sum of the individual inductances of the windings. This arrangement can, for example, result in an inductance eight times that of a single coil, even though only four individual coils are present, thereby strengthening the magnetic field and increasing the sensitivity of the sensor while maintaining compactness.

[0036] In one embodiment, the inductive wheel sensor further comprises at least one electronic unit for processing resonant circuit signals generated by the at least one sensor coil and for outputting detection signals to external units and / or for internal system functions. This electronic unit can be integrated on the same circuit board and enables a compact design with short signal paths.

[0037] In another embodiment, the inductive wheel sensor comprises two sensor coils, each sensor coil being configured in a double-D configuration and having two D-shaped coil sections, each with one flat and one curved side. The two sensor coils are arranged in the wheel sensor such that, in the intended mounting state of the wheel sensor on a rail, they lie one behind the other in the longitudinal direction of the rail. This arrangement enables the determination of the direction of travel and speed of rail vehicles by evaluating the temporal sequence of the signals. D / PINUXR-039-P2

[0038] - 6 -

[0039] In one embodiment, the inductive wheel sensor further comprises at least one damping coil associated with the at least one sensor coil. This damping coil enables both the simulation of wheel passes for testing purposes and the calibration of the sensor to compensate for

[0040] 5 manufacturing tolerances.

[0041] In a further embodiment, the at least one damping coil is configured in a double-D configuration with two D-shaped damping regions and is arranged as a coupling coil to the at least one sensor coil. This configuration ensures optimal magnetic coupling between the damping and sensor coils.

[0042] In an embodiment with two sensor coils, two damping coils are provided, with each sensor coil being assigned a damping coil. This enables the independent simulation and calibration of both sensor coils.

[0043] In a further embodiment, the inductive wheel sensor also includes a control unit for selectively activating the at least one damping coil for simulation or calibration purposes. This control unit coordinates the various operating modes and prevents conflicts between simulation, calibration, and normal detection, so that the damping coil can be used for two different operating modes, which can be executed separately in time: a simulation mode for functional testing and a calibration mode for adjusting the resonant frequency of the wheel sensor.

[0044] In simulation mode, the damping coil is temporarily activated according to a predefined pattern to simulate a wheel crossing. A reference pattern determined from laboratory tests is used, which replicates the characteristic temporal sequence of damping during a real wheel crossing. The damping coil generates eddy currents and / or a shift in the resonant frequency through magnetic coupling with the sensor coil, thereby changing the sensor coil's resonant circuit parameters in a manner corresponding to a real wheel crossing. An evaluation unit detects these changes and can thus verify the proper functioning of the detection system.5 During the simulation, a flag is typically set, which the D / PINUXR-039-P2

[0045] - 7 -

[0046] Forwarding the detected crossing information to external systems is prevented in order to avoid false alarms. This will be explained in more detail below in connection with the description of a method according to the invention.

[0047] 5. In calibration mode, the damping coil is used to fine-tune the resonant frequency of the sensor coil. Controlled activation of the damping coil couples additional capacitances into the sensor coil's resonant circuit, allowing its resonant frequency to be shifted precisely. This process can be used both during manufacturing to compensate for production tolerances and during operation to compensate for environmental influences such as temperature fluctuations or aging effects. The activation parameters required for optimal frequency setting are stored in the wheel sensor's memory and can be applied automatically as needed.

[0048] The two operating modes are typically mutually exclusive and are executed in a coordinated manner. Simulation mode is typically activated during periods of inactivity or during targeted maintenance cycles, while calibration mode is used either continuously at low intensity or for frequency stabilization during announced passing of a rail vehicle. Intelligent control logic ensures that neither simulation nor calibration interferes with the measurement during an active wheel crossing.

[0049] The dual function is enabled by a corresponding circuit configuration of the 5 damping coil, which supports various activation patterns and activation intensities. Dynamic, time-limited activation patterns are used for simulation, while static or slowly changing activation values ​​are used for calibration. Control is managed by the control unit, which retrieves the appropriate activation parameters from memory depending on the operating mode and forwards them to the damping hardware. Note that when the terms evaluation unit or control unit are used here, they are to be understood functionally. Such "units" are typically implemented using a single, appropriately designed electronic component. 5 D / PINUXR-039-P2

[0050] - 8 -

[0051] In an inventive method for simulating a wheel crossing with an inductive wheel sensor having at least one damping coil and at least one associated sensor coil, the at least one damping coil is used to dampen the associated sensor coil.

[0052] 5. Simulation of a wheel crossing is activated, and the resulting changes in the resonant circuit parameters of the sensor coil are recorded. This method enables a realistic simulation of wheel crossings for checking and optimizing the sensor system without actual train movements. Note that while this method can be advantageously implemented with a wheel sensor according to the invention with sensor coils in a double-D configuration, it is not limited to such sensor coils but can also be implemented with sensor coils of any other shape and associated damping coils. Furthermore, note that the association of sensor coils and damping coils is reciprocal; that is, one can speak of a damping coil associated with a sensor coil as well as of sensor coils associated with a damping coil.

[0053] In one embodiment of the method, using a wheel sensor with two damping coils, each associated with a sensor coil, the two sensor coils are arranged in the wheel sensor such that, in the intended mounting state of the wheel sensor on a rail, they lie one behind the other in the longitudinal direction of the rail. The two damping coils are activated sequentially to generate a time-shifted damping of the two sensor coils. This simulates the natural sequence of a wheel passing over both sensor coils.

[0054] In another embodiment, different wheel sizes are simulated by varying the activation duration of the damping coils, and different speeds are simulated by varying the time offset between activations. This enables comprehensive testing of the wheel sensor under various operating conditions.

[0055] In one embodiment, the output of 5 detection signals to external units is suppressed during the simulation. This prevents false alarms. D / PINUXR-039-P2

[0056] - 9 - during the test phase and enables undisturbed functional testing. Such suppression can, for example, include setting a flag to prevent the transmission of a detected crossing during the simulation and issuing an error message only in the case of an undetected crossing. Standard practice.

[0057] 5. A flag is understood to be an indicator that displays a specific state or condition. In software development, a flag is typically a variable that can assume two states (e.g., set / not set or true / false). In hardware, a flag can be implemented by a special bit in a register that is set or reset by electrical signals. Both software and hardware flags can be used in this context.

[0058] In another embodiment, a status message is issued after the simulation. This message includes an error message if a crossing is not detected and / or a calibration request if the signal strength is outside a predefined range. Predefined target values ​​are compared with the measured signal strengths to evaluate the functionality of the wheel sensor. Predefined target values ​​are understood to be, in particular, reference values ​​that were determined during the development or calibration of the wheel sensor and stored as a benchmark for proper function.

[0059] In one embodiment, the simulation is based on a reference pattern determined from laboratory tests. The reference pattern represents the characteristic temporal sequence of damping during a real wheel crossing and ensures a realistic simulation.

[0060] In another embodiment, after the wheel sensor has been mounted on a rail as intended, a simulated wheel crossing is performed for self-testing. This allows for immediate functional testing after installation.

[0061] In an inventive method for calibrating an inductive wheel sensor with at least one damping coil and at least one associated sensor coil, a resonance frequency of the at least one sensor coil is adapted to a target frequency by activating the D / PINUXR-039-P2

[0062] - 10 -

[0063] Damping coil for coupling additional capacitances into a resonant circuit built with the sensor coil. This method enables precise calibration of the sensor and compensates for manufacturing variations.

[0064] 5 In one embodiment, the resonant frequency of the at least one sensor coil is checked before delivery of the wheel sensor, and if it deviates from a target frequency, the resonant frequency is adjusted by activating the damping coil, the activation parameters used to activate the damping coil being stored in a memory of the wheel sensor. This ensures optimal tuning of the sensor at the factory.

[0065] In another embodiment, the damping coil is automatically activated during operation of the wheel sensor according to the five stored activation parameters for continuous compensation of manufacturing tolerances. This automatic readjustment increases manufacturing efficiency and quality.

[0066] In one embodiment, an automated recalibration is performed at regular or irregular intervals during operation of the wheel sensor. During this recalibration, updated activation parameters of the damping coil are determined and stored in a memory of the wheel sensor. This ensures consistently high sensor performance throughout the entire service life of the device by compensating for environmental influences and aging effects.

[0067] Further details and advantages of the invention will become apparent from the following purely exemplary and non-limiting description of embodiments in conjunction with the drawing comprising ten figures. D / PINUXR-039-P2

[0068] - 11 -

[0069] BRIEF DESCRIPTION OF THE DRAWING

[0070] Fig. 1 shows a highly schematic representation of a section of a rail with a wheel sensor according to the invention arranged on it.

[0071] 5. Design.

[0072] Fig. 2 shows an isometric view of a lower housing part of the wheel sensor according to Fig. 1.

[0073] Fig. 3 shows the lower part of the housing according to Fig. 2 in a side view.

[0074] Fig. 4 shows a top view of a printed circuit board of a wheel sensor according to the invention with two sensor coils, each of which is designed in a double-D configuration with two D-5 shaped coil areas.

[0075] Fig. 5 shows an isometric view of the printed circuit board according to Fig. 4.

[0076] Fig. 6 shows the expected distribution of field lines for a sensor coil in a double-D configuration according to Fig. 4.

[0077] Fig. 7 shows a typical damping profile when a wheel of a rail vehicle passes a wheel sensor according to Fig. 1. 5

[0078] Fig. 8 shows a schematic exploded view of a sensor coil and an associated damping coil, each designed in a double-D configuration.

[0079] Fig. 9 shows a circuit diagram of a possible construction of a sensor coil in a double-D configuration according to Fig. 4.

[0080] Fig. 10 shows a schematic diagram of the sensor coil and associated damping coil according to Fig. 9. 5 D / PINUXR-039-P2

[0081] - 12 -

[0082] DESCRIPTION OF PREFERRED EXECUTION FORMS

[0083] Fig. 1 schematically shows a section of a rail designated in its entirety by 10, together with a device arranged on it and in its entirety

[0084] 5 with 12 the wheel sensor according to the invention with a protective plate 14 and a housing lower part 16.

[0085] The section of rail 10 shown is a typical railway rail with a rail head 18, the upper side of which forms a running surface 20, a rail web 22 and a rail foot 24.

[0086] In the illustrated embodiment, a device holder with a base bracket 26, which engages the rail foot 24, is used to attach the wheel sensor 12 to the rail 10. The base bracket 26 clamps the rail foot 24 in a claw-like manner, with the part of the base bracket 26 visible in Fig. 1 being clamped against a corresponding counterpart on the opposite side of the rail foot 24 by means of one or more clamping screws. The device holder shown is therefore a type that does not require drilling through the rail 10. Theoretically, the base bracket can also be attached to the rail web 22 via corresponding holes and retaining screws.

[0087] The device holder further comprises an adapter plate 28, wherein, in this embodiment, the adapter plate 28 and the base holder 26 are fixed by means of two clamping screws which are "height-adjustable" in two elongated holes 30. To clarify the design of the adapter plate 28, the clamping screws, which actually pass through the two elongated holes 30 in the adapter plate 28 to fix the adapter plate 28 relative to the base holder 26, as well as the fastening screws, which actually pass through the two mounting openings 32 to attach the wheel sensor 12 to the adapter plate 28, have been omitted from the schematic representation in Fig. 1. The term "height-adjustable" refers to the fact that by sliding the adapter plate along the elongated holes 30, the distance of the wheel sensor 12 to the running surface of the rail 10, and thus the height of the wheel sensor 12 above the rail foot 24, can be changed. D / PINUXR-039-P2.

[0088] - 13 -

[0089] Figures 2 and 3 show the lower housing part 16 from different angles. It has an elongated support section 34 for supporting a circuit board shown in Figures 4 and 5, which carries two sensor coils, and a recessed receiving section 36 for receiving further units and components such as

[0090] 5 evaluation and control units, cable connections, etc. and a connecting section 38 with two mounting openings 40, which correspond to the mounting openings 32 in the adapter plate 28 (Fig. 1).

[0091] The lower housing section 16 is completed by a protective plate 14 (Fig. 1) to form a housing designed to accommodate the circuit board with the integrated double-D coils, enabling a compact and flat design for the wheel sensor. It protects the circuit board and the integrated coils against environmental influences such as dust, moisture, and mechanical stress, and is made of a suitable material that withstands the harsh conditions typically encountered in railway environments. After the circuit board and other components are inserted, they can be potted in the housing with a curable plastic, resulting in a particularly stable and vibration-resistant wheel sensor unit. Depending on the plastic used, an upper layer can seal the housing on the coil side, eliminating the need for a separate protective plate 14.The housing may also contain shielding elements to protect the wheel sensor from electromagnetic interference.

[0092] Figures 4 and 5 show the printed circuit board 42 designed according to the invention in five different views. In this embodiment, it carries two sensor coils, designated 44 and 46 respectively. Each sensor coil 44, 46 has two D-shaped coil sections 48, 50 and 52, 54 respectively, each with one straight and one curved side. The D-shaped coil sections 48, 50 of sensor coil 44 are arranged side by side such that their straight sides face each other and their curved sides point away from each other. The D-shaped coil sections 52, 54 of sensor coil 46 are arranged in the same way. In the intended mounting state of the wheel sensor on a rail, all D-shaped coil sections 48–54 lie in a substantially horizontal plane, with their straight sides extending transversely to the longitudinal direction of the rail. D / PINUXR-039-P2

[0093] - 14 -

[0094] The two sensor coils 44 and 46 are arranged in the wheel sensor such that, in the intended mounting state of the wheel sensor on a rail, they lie one behind the other in the longitudinal direction of the rail.

[0095] 5 The sensor coils 44, 46 are implemented as conductive traces on the printed circuit board 42, instead of as discrete wound coils. This integration of the coils directly onto the printed circuit board reduces the manufacturing variability typical of wound coils and improves the consistency of the sensor performance across different units.

[0096] In this embodiment, each sensor coil 44, 46 is advantageously assigned a damping coil corresponding to it in shape and size, which is located on the other side of the circuit board 42 and is therefore not shown separately here. The shape and function of the damping coils will be discussed below. 5

[0097] Fig. 6 shows the expected distribution of field lines for a sensor coil 44 with two D-shaped coil sections 48, 50. During operation, the sensor coil generates a magnetic field, indicated by the field lines 56 (only some of which are labeled for clarity), which extends over the straight sections of the D-shaped coil sections 48, 50 and provides an optimized field geometry for improved detection. The double-D configuration of the sensor coils enables a more homogeneous field line distribution perpendicular to the rail to cover the critical detection area. This improves detection accuracy, especially in boundary regions, and reduces false detections.

[0098] Fig. 7 schematically shows two typical damping curves as they occur with a wheel sensor according to Figure 1, more precisely in the resonant circuits formed by the sensor coils 44 and 46 shown in Figures 4 and 5, when a wheel of a rail vehicle passes over them. The representation here is chosen so that the wheel first passes sensor coil 44, then sensor coil 46, i.e., from left to right in Figure 4. Damping curve K44 represents the response of sensor coil 44 (more precisely, the resonant circuit formed by it), and damping curve K46 represents the response of sensor coil 46. D / PINUXR-039-P2

[0099] - 15 -

[0100] (more precisely, of the resulting resonant circuit). The abscissa represents time t, and the ordinate schematically depicts a suitable unit of measurement for representing a changing amplitude A. The curve shows a characteristic pattern of amplitude changes, representing the different stages of wheel recognition.

[0101] 5 correspond. At time t1, sensor coil 44 is maximally damped, at time t2, sensor coil 46.

[0102] Such damping curves can also be generated in the laboratory and then used in installed wheel sensors to simulate wheel crossings under various conditions by damping the sensor coils using controlled damping coils. Figure 8 schematically shows a sensor coil 44 with two D-shaped coil sections 48, 50, to which a corresponding damping coil 58 with two D-shaped coil sections 60, 62 is assigned. By appropriately controlling the damping coil 585, wheel crossings can be simulated in the sensor coil 44. Additional capacitors can also be coupled into the sensor coil 44 to adjust the resonant frequency of the damping coil 44. In a preferred embodiment of the wheel sensor, a corresponding damping coil is also provided for the second sensor coil.

[0103] Fig. 9 is a highly schematic diagram illustrating the construction of a sensor coil with two D-shaped coil sections 48 and 50, each consisting of interconnected individual coils (four individual coils in the illustrated embodiment) on different layers PCB1, PCB2, PCB3, and PCB4 of a printed circuit board. The individual coils with inductances LL and LR are interconnected to provide eight times the inductance of a single coil.

[0104] The circuit is configured such that the inductances of the left D-half (LL) and the right D-half (LR) are equal, where L = LL = LR. The magnetic coupling between the individual coils (indicated by "M") is described by the mutual inductance M, which is calculated as M = kx A / (L LX LR) = kx L results, where k represents the coupling factor between the coils (k=1 idealized). The constructive magnetic coupling between the layers creates a D / PINUXR-039-P2

[0105] - 16 -

[0106] Total inductance L ges = 8L, which results in an inductance eight times that of a single coil despite only four individual coils.

[0107] The individual coils are connected via vias between the PCB layers.

[0108] The five coils are connected together, forming a continuous series circuit. This arrangement strengthens the magnetic field and increases the sensor's sensitivity while maintaining its compact size. Simultaneously, connecting coil elements in parallel across multiple layers reduces the DC resistance, thereby improving the overall coil system's quality factor.

[0109] The double-D coil geometry enables a stronger and better focused magnetic field through the coupling or superposition of the two coils. This allows the magnetic field to "look" very far upwards (and also downwards) and is superior to conventional measurement methods in the borderline regions (swarm range). 5

[0110] Fig. 10 shows a schematic diagram of a circuit for generating a damping effect. The circuit comprises a sensor coil 44 and an associated damping coil 58. The sensor coil 44 forms a first resonant circuit 66 with a capacitor 64 in a manner known per se. The damping coil 58 forms a second resonant circuit 70 with a switchable damping element 68. As indicated by the double arrow 72, the coils 44 and 58 are magnetically coupled to each other during operation. The damping element 68 is controlled by a control unit 76, typically implemented by a microcontroller, in the manner described above to generate a simulation or to set a specific resonant frequency in the first resonant circuit 66. In some embodiments, an algorithm is implemented in the wheel sensor that enables precise control of the damping effect.The length of the damping pattern and the time offset between the reproduced patterns can be adjusted to simulate wheels with different diameters or at different speeds.

[0111] REFERENCE MARK LIST

[0112] 10 Rail 12 Device D / PINUXR-039-P2

[0113] - 17 -

[0114] 14 Sensor plate

[0115] 16 sensor housings

[0116] 18 Railhead

[0117] 20 tread surface

[0118] 22 rail bridge

[0119] 24 rail foot

[0120] 26 Base bracket

[0121] 28 Adapter plate

[0122] 30 slotted holes

[0123] 32 Mounting opening

[0124] 34 Support section

[0125] 36 Recording section

[0126] 38 Connecting section

[0127] 40 Mounting opening

[0128] 42 circuit boards

[0129] 44 Sensor coil

[0130] 46 Sensor coil

[0131] 48 D-shaped coil area

[0132] 50 D-shaped coil area

[0133] 52 D-shaped coil area

[0134] 54 D-shaped coil area

[0135] 56 field lines

[0136] 58 Damping coil

[0137] 60 D-shaped coil area

[0138] 62 D-shaped coil area

[0139] 64 capacity

[0140] 66 Oscillating circuit

[0141] 68 Damper element

[0142] 70 Oscillating circuit

[0143] 72 Magnetic Coupling

[0144] 74 Control unit

[0145] K44 damping curve

[0146] K46 Damping curve t Time t1 Time D / PINUXR-039-P2

[0147] - 18- t2 time

[0148] A Amplitude

Claims

D / PINUXR-039-P2 - 19 - PATENT CLAIMS 1. Inductive wheel sensor for rail transport, comprising: at least one printed circuit board with at least one sensor coil, 5 wherein the at least one sensor coil has two D-shaped coil sections, each with a straight and a curved side, wherein the D-shaped coil sections of the at least one sensor coil are arranged side by side such that their straight sides face each other and their curved sides point away from each other, and wherein the two D-shaped coil sections of the at least one sensor coil are arranged in the wheel sensor such that, in the intended mounting state of the wheel sensor on a rail, they each lie in a substantially horizontal plane and their straight sides extend transversely to the longitudinal direction of the rail. 5 2. Inductive wheel sensor according to claim 1, wherein the two D-shaped coil sections of the at least one sensor coil are formed by a continuous conductor track.

3. Inductive wheel sensor according to claim 1 or 2, wherein each D-shaped coil section of the at least one sensor coil comprises two to six, preferably three to five, more preferably four interconnected individual coils.

4. Inductive wheel sensor according to one of the preceding claims, wherein the at least one sensor coil extends over several layers of the printed circuit board.

5. Inductive wheel sensor according to claim 4, wherein the windings of the D-shaped coil sections of the at least one sensor coil are spatially arranged on the multiple layers such that, in the operating state, a total inductance results from constructive magnetic coupling between the layers which is greater than the sum of the individual inductances of the windings.

6. Inductive wheel sensor according to one of the preceding claims, further comprising at least one electronic unit for processing by means of the D / PINUXR-039-P2 - 20 - at least one sensor coil generated resonant circuit signals and for outputting detection signals to external units and / or for internal system functions.

7. Inductive wheel sensor according to one of the preceding claims, 5 comprising two sensor coils, each sensor coil being configured in a double-D configuration with two D-shaped coil areas, each having a straight and a curved side, the two sensor coils being arranged in the wheel sensor such that, in the intended mounting state of the wheel sensor on a rail viewed in the longitudinal direction of the rail, they are located one behind the other.

8. Inductive wheel sensor according to one of claims 1 to 6, further comprising at least one damping coil associated with the at least one sensor coil. 5 9. Inductive wheel sensor according to claim 8, wherein the at least one damping coil is configured in a double-D configuration with two D-shaped damping regions and is arranged as a coupling coil to the at least one sensor coil.

10. Inductive wheel sensor according to claim 7 and claim 9, wherein two damping coils are provided and each sensor coil is assigned a damping coil.

11. Inductive wheel sensor according to one of claims 8 to 10, further comprising a control unit for selectively activating the at least one damping coil for simulation or calibration purposes.

12. Method for simulating the passage of a wheel of a rail vehicle using an inductive wheel sensor with at least one damping coil and at least one associated sensor coil, in particular a wheel sensor according to one of claims 8 to 11, comprising: Activating at least one damping coil to dampen its associated sensor coil to simulate a wheel crossing and D / PINUXR-039-P2 - 21 - Capturing the resulting changes in the resonant circuit parameters of the sensor coil.

13. Method according to claim 12 in a wheel sensor with two 5 damping coils, each of which is assigned a sensor coil, wherein the two sensor coils are arranged in the wheel sensor such that, in the intended mounting state of the wheel sensor on a rail viewed in the longitudinal direction of the rail, they lie one behind the other, wherein the two damping coils are activated sequentially to generate a time-shifted damping of the two sensor coils.

14. Method according to claim 13, wherein different wheel sizes are simulated by varying the activation duration of the damping coils and different speeds are simulated by varying the time offset between the activations.5 15. A method according to any one of claims 12 to 14, wherein the output of detection signals to external units is suppressed during the simulation.

16. A method according to any one of claims 12 to 15, wherein, after the simulation, a status message is output which includes an error message in the event of an undetected crossing and / or a calibration request in the event of signal strengths outside a predefined range. 5 17. Method according to claim 12, wherein the simulation is based on a reference pattern determined from laboratory tests.

18. Method according to one of claims 12 to 17, wherein, after the wheel sensor has been mounted on a rail as intended, a simulated wheel crossing is carried out for self-testing.

19. Method for calibrating an inductive wheel sensor for rail transport with at least one damping coil and at least one sensor coil associated with it, in particular a wheel sensor according to one of the D / PINUXR-039-P2 - 22 - Claims 8 to 11, comprising adapting a resonant frequency of the at least one sensor coil to a target frequency by activating the damping coil to couple additional capacitances into a resonant circuit constructed with the sensor coil. 5 20. Method according to claim 19, wherein, prior to delivery of the wheel sensor, a resonance frequency of the at least one sensor coil is checked and, if it deviates from a target frequency, the resonance frequency is adjusted by activating the damping coil, wherein the activation parameters used to activate the damping coil are stored in a memory of the wheel sensor.

21. Method according to claim 20, wherein during operation of the wheel sensor the damping coil is automatically activated according to the stored 5 activation parameters for continuous compensation of manufacturing tolerances.

22. The method of claim 19, wherein during operation of the wheel sensor an automated recalibration is performed at regular or irregular intervals, in which updated activation parameters of the damping coil are determined and stored in a memory of the wheel sensor. 5

Images