AU2022218511B2 - Sensor device, arrangement, and method for detecting a change in a magnetic field - Google Patents

Abstract

Sensor device, arrangement and method for detecting a change in a magnetic field The invention relates to a sensor device (2) for detecting a change in a magnetic field (11) which is brought about by a wheel (7) of a rail vehicle (8) approaching the sensor device (2) on a running rail (1), with at least one receive oscillating circuit (3) which is configured to produce a receive voltage (UE) brought about by the magnetic field (11), and with at least one evaluator (4) which is connected to the receive oscillating circuit (3) and is configured to evaluate the receive voltage (UE). In order to avoid miscounts, the invention provides that the sensor device comprises at least one current source (5) which has at least two terminal contacts (9) connectable to the running rail (1) and which is configured to provide a rail current (I s) which can be fed into the running rail (1) at the terminal contacts (9), wherein the magnetic field (11) in a rail section (26) between the terminal contacts (9) can be produced from the rail current (Is) fed into the running rail (1) and the receive oscillating circuit (3) is configured to be arrangeable in the rail section (26) between the terminal contacts (9). The invention furthermore relates to a method for detecting a change in a magnetic field (11) which is brought about by a wheel (7) of a rail vehicle (3) approaching the sensor device (2) on a running rail (1). (Fig. 1) 1/4 FIG1 2 1 IsF 12 5Q 59 3 15 6

Description

1/4

FIG1 2

1

IsF

12 5Q

59 3

15

Description

Sensor device, arrangement and method for detecting a change

in a magnetic field

The present application claims priority to German Patent

Application No. 10 2021 209 644.1, filed on 2 September 2021,

the content of which is incorporated herein by reference in

its entirety.

The disclosure relates to a sensor device for detecting a

change in a magnetic field which is brought about by a wheel

of a rail vehicle approaching the sensor device on a running

rail, with at least one receive oscillating circuit which is

configured to produce a receive voltage brought about by the

magnetic field, and with at least one evaluator which is

connected to the receive oscillating circuit and is configured

to evaluate the receive voltage.

The disclosure furthermore relates to a method for detecting a

change in a magnetic field which is brought about by a wheel

of a rail vehicle approaching the sensor device on a running

rail.

Inductively operating axle-counting sensors are sufficiently

known in track vacancy detection technologies for railway

installations. They are used to count the axles or rather the

wheels of a train as it passes over a sensor device. It is in

this way established, for example, whether a specific track

section is or is not occupied by a train.

Such sensor devices are described for example in DE 10 2016 211 354 Al, DE 10 2016 201 896 Al or

DE 10 2014 207 409 Al.

As already mentioned above, in a railway engineering

installation, track sections are evaluated as vacant or

occupied by way of such sensor devices known as axle-counting

sensors. As a function thereof, track sections are or are not

cleared for transit by a train. It is therefore of particular

importance to the safety of the railway engineering

installation for the sensor devices used to ascertain the

wheel passages of the rail vehicles in as error-free a manner

as possible. "Miscounts" which may occur due to measurement

inaccuracies are to be avoided. Considerable effort is taken

to identify or avoid miscounts so that they cannot lead to

accidents. In any event, it is desirable to provide improved

sensor devices with which miscounts can be avoided.

It is an object of the present invention to substantially

overcome, or at least ameliorate, one or more disadvantage of

existing arrangements, or provide a useful alternative. Some

embodiments of the present invention are intended to provide a

sensor device and a method of the initially stated type with

which miscounts can be avoided.

According to one aspect, there is provided a sensor device for

detecting a change in a magnetic field which is brought about

by a wheel of a rail vehicle approaching the sensor device on

a running rail, with at least one receive oscillating circuit

which is configured for producing a receive voltage brought

about by the magnetic field, and with at least one evaluator

which is connected to the receive oscillating circuit and is

configured to evaluate the receive voltage, wherein at least one current source which has at least two terminal contacts connectable to the running rail and which is configured to provide a rail current which can be fed into the running rail at the terminal contacts, wherein the magnetic field in a rail section between the terminal contacts can be produced from the rail current fed into the running rail and the receive oscillating circuit is configured to be arrangeable in the rail section between the terminal contacts; and whe r e in the terminal contacts of the current source are arranged on one side of the running rail and the at least one receive oscillating circuit is arranged on the other side of the running rail.

According to another aspect, there is provided an arrangement with at least one running rail and with at least one sensor device for detecting a magnetic field change which is brought about by a wheel of a rail vehicle approaching the sensor device on the running rail, wherein the sensor device is arranged on the running rail, whe r e in the sensor device is configured according to the above aspect.

According to a further aspect, there is provided a method for detecting a change in a magnetic field which is brought about by a wheel of a rail vehicle approaching the sensor device on a running rail, wherein a rail current is fed into a rail section of the running rail between at least two terminal contacts of a current source, a magnetic field is produced from the alternating current and a receive voltage is produced from the magnetic field in a receive oscillating circuit, and the receive voltage and a change in receive voltage brought about by a magnetic field change are evaluated, wherein t he terminal contacts of the current source are arranged on

3a

one side of the running rail and the at least one receive oscillating circuit is arranged on the other side of the running rail.

The sensor device according to the present disclosure provides at least one current source which has at least two terminal contacts connectable to the running rail and which is configured to provide a rail current which can be fed into the running rail at the terminal contacts, wherein the magnetic field in a rail section between the terminal contacts can be produced from the rail current fed into the running rail and the receive oscillating circuit is configured to be arrangeable in the rail section between the terminal contacts.

According to the method disclosed below, a rail current is fed

into a rail section of the running rail between at least two

terminal contacts, a magnetic field is produced from the

alternating current and a receive voltage is produced from the

magnetic field in a receive oscillating circuit, and the

receive voltage and a change in the receive voltage brought

about by the magnetic field change are evaluated

In some embodiments, the rail current is fed into the running

rail during operation of the sensor device by way of the

terminal contacts and the magnetic field around the running

rail is produced by the alternating current flowing in the

running rail. This magnetic field is changed by the wheel of a

rail vehicle passing the sensor device, this being detectable

with the assistance of the receive oscillating circuit and the

evaluator. In comparison with known sensor devices, it is thus

possible to dispense with the "transmitter oscillating

circuits" for producing the magnetic field.

It has furthermore been found that the sensor device according

to some embodiments is less susceptible to miscounts brought

about, for example, by iron parts, such as for example

magnetic brakes, located on the bottom of the rail vehicle.

This should be considered particularly advantageous because

fewer miscounts occur as a consequence.

The magnetic field produced by way of the sensor device has

magnetic flux lines which extend approximately concentrically around the rail. This concentric course of the magnetic flux lines results in the lower sensitivity of the sensor device in the region above the upper edge of the rail.

The terminal contacts of the current source are preferably connected in a particularly low-resistance manner to the running rail in order to minimize power losses and to optimally conduct the rail current into the running rail. A powerful rail current of a number of amperes is advantageous for obtaining a clear and readily measurable change in receive voltage on passage of a wheel. The terminal contacts can also be connected to the running rail using existing fastening holes or the like. The receive oscillating circuit is made up of a receive coil, a capacitor and a resistor. The evaluator connected to the receive oscillating circuit may for example have a microcontroller which serves, for example, to perform computing operations. The receive voltage is evaluated by the evaluator and the magnetic field change brought about by the approaching or passing wheel is consequently identified. In the event of a magnetic field change representative of wheel passage being identified, the evaluator can form an output signal for further processing within the railway engineering installation. To this end, a threshold value for the change in receive voltage or also a change in phase angle, optionally taking account of the rail current, above which a magnetic field change is assumed to be brought about by a wheel, may be stored in the evaluator. This threshold value is parameterizable.

The solution may be further developed by advantageous embodiments as are described below.

The evaluator may accordingly be connected to the current source and be configured to evaluate the rail current. This has the advantage that a change in receive voltage relative to the rail current can be particularly unambiguously ascertained.

In one particularly advantageous embodiment, the evaluator can be configured to evaluate a change in the relative phase angles of the receive voltage and rail current. This has the advantage that, on consideration of the phase angles, a clearly measurable change in the magnetic field change brought about by a wheel is apparent. Passage of the wheel is consequently particularly simply detectable and mismeasurements can be particularly effectively avoided.

In order to detect a still clearer result in the magnetic field change brought about by a wheel, the current source can be configured to provide the rail current substantially with a resonant frequency of the receive oscillating circuit. In the case of a rail current operated at the resonant frequency, the magnetic field, which is an alternating magnetic field, is likewise alternated at the resonant frequency and so brings about optimum behavior of the receive oscillating circuit.

In a further advantageous embodiment, the sensor device may have at least one signal processing device for the receive voltage and/or the rail current which is configured for level adaptation, filtering and/or amplification. This has the advantage that the signals from the receive oscillating circuit are optimally conditioned and can accordingly be particularly effectively evaluated by the evaluator. In addition, conversion to a square-wave signal, which is simpler to process and in which for example a modification in phase angle is more readily identifiable, may also proceed.

In order likewise to ascertain the direction of movement of

the detected wheel, the sensor device may have at least two

receive oscillating circuits arrangeable adjacent one another

in the longitudinal direction of the rail. The receive

oscillating circuits arranged adjacent one another of this

embodiment are influenced timewise in succession by the

approaching wheel of the rail vehicle, such that the direction

of movement can be ascertained from the time difference.

In order to ensure optimum protection from environmental

influences, the sensor device may have at least one housing in

which the at least one receive oscillating circuit is

arranged.

The disclosure further also relates to an arrangement with at

least one running rail and with at least one sensor device for

detecting a magnetic field change which is brought about by a

wheel of a rail vehicle approaching the sensor device on the

running rail, the sensor device being arranged on the running

rail. The disclosure provides that the sensor device is

configured according to one of the previously described

embodiments.

In order to improve mounting and installation of the

arrangement, the terminal contacts of the current source can

be arranged on one side of the running rail and the at least

one receive oscillating circuit on the other side of the

running rail.

In a further advantageous embodiment of the disclosed arrangement, a receive coil of the receive oscillating circuit may be positioned relative to the running rail in such a way that a receive voltage measurable by the evaluator is produced in each case both with and without a magnetic field change. This has the advantage that the magnetic field change brought about by the approaching wheel can be particularly effectively detected.

Embodiments of the invention are explained below on the basis of exemplary embodiments in the drawings, in which:

Figure 1 shows a schematic representation of exemplary embodiments of a disclosed arrangement and sensor device;

Figure 2 shows a schematic representation of the embodiments in Figure 1 with the influence of a passing wheel of a rail vehicle;

Figure 3 shows a schematic representation of a circuit diagram of the exemplary embodiment of Figures 1 and 2;

Figure 4 shows a schematic representation of a further exemplary embodiment of the sensor device;

Figure 5 shows a schematic representation of the embodiment in Figure 4 in another view.

Embodiments of the invention are firstly explained on the basis of the exemplary embodiment in Figures 1-3.

Figure 1 shows a running rail 1 depicted in cross-section which is part of a route of a railway engineering installation and over which rail vehicles transit. An exemplary embodiment of the sensor device 2 is provided in order to detect axles or rather wheels 7 of rail vehicles 8 passing along the running rail 1.

In the exemplary embodiment of Figures 1-3, the sensor device 2 comprises a receive oscillating circuit 3, an evaluator 4 and a current source 5. The sensor device 2 forms, together with the running rail 1 on which the sensor device 2 is arranged, an arrangement 6. Figure 2 depicts a state in which a wheel 7 of a rail vehicle 8 is located in the region of the sensor device 2.

The current source 5 is configured to provide an alternating current and comprises two terminal contacts 9. A rail current I s produced by a current source 5 is provided to the terminal contacts 9 via lines 10. The terminal contacts 9 are in each case connected in as low-resistance a manner as possible to the running rail 1, such that the rail current I s can be fed into the running rail 1. The terminal contacts 9 are spaced apart from one another by a distance A in a longitudinal direction L of the rail. During operation of the sensor device 2, the rail current I s thus flows in a rail section 26 between the terminal contacts 9.

As is conventional, the running rail 1 is produced from electrically conductive material, such as for example steel. As a consequence, due to the flowing current Is, a magnetic field 11 forms substantially concentrically around the running rail 1. Figures 1 and 2 depict the magnetic flux lines diagrammatically with dashed arrows. So that a magnetic field

11 optimized for function of the sensor device 2 is produced,

the current source 5 in the embodiment in Figs. 1 to 3

provides a relatively strong rail current I s of a strength of

a number of amperes.

For reasons of space and for simple installation, in the

exemplary embodiment of Figures 1-3, the terminal contacts 9

are arranged opposite the receive oscillating circuit in a

central region of the running rail 1 below the rail head. The

terminal contacts 9 may for example be installed in existing

holes in the running rail 1. The frequency of the rail current

I s produced by the current source 5 preferably corresponds to

a resonant frequency of the receive oscillating circuit 3,

which can also be denoted the working frequency.

The receive oscillating circuit 3 comprises a receive coil 12

together with a capacitor 13 and a resistor 14, which are

shown in Figure 3. The receive oscillating circuit 3 is

constructed as an antiresonant circuit. The receive

oscillating circuit 3 is arranged in a housing 15 for

protection.

As shown in Figures 1 and 2, the receive oscillating circuit 3

is positioned such that the magnetic field 11 passes through

the receive coil 12. The coil, which is depicted by way of

example as a cylinder in Figs. 1-3, is arranged with the

cylinder axis substantially transverse of the magnetic field

lines. This is substantially also transverse of the

longitudinal direction L of the rail. The receive coil 12 is

furthermore positioned in the magnetic field 11 such that the

magnetic field lines pass through it in the state both with

wheel 7 and without wheel 7. An electrical voltage is

consequently induced in the receive oscillating circuit 3 during operation. As shown Figures 1 and 2, the magnetic field

11 is modified by the passing wheel 7 of the rail vehicle 8.

Due to the magnetic field change, the voltage induced in the

receive oscillating circuit 3 is also modified, this being

ascertained by the evaluator 4 and described in greater detail

below. The receive coil 12 is positioned such that the

magnetic field 11 passes through in a transverse direction Q

which is located substantially transverse of the longitudinal

direction L of the rail. The receive coil 12 is fixedly

arranged relative to the running rail 1, so that the position

thereof is not modified, for example not even due to passing

rail vehicles 8 or the effects of weather. This may proceed,

for example, by suitable fastening means on the running rail

1.

In the embodiment in Figs. 1-3, the evaluator 4 is connected

for signaling both to the current source 5 and to the receive

oscillating circuit 3. The evaluator 4 accordingly receives

both the rail current I s provided by the current source 5 and

the voltage induced in the receive oscillating circuit 3,

which is hereinafter denoted U_E and shown in Figure 3.

In the exemplary embodiment of the sensor device 2 shown in

Figures 1-3, the evaluator 4 comprises two signal processing

devices 16, 17. The signal processing devices 16, 17

preprocess the input signals, i.e. the rail current I s and

the voltage U_E. This signal preprocessing may be for example

amplification, level adaptation or filtering. The signals are

then in each case converted into a square-wave signal in a

further processing device 18, 19.

In the exemplary embodiment of Figures 1-3, the evaluator 4

furthermore comprises an analog analytical device 20 which produces an analog signal 23 corresponding to the phase shift t p from the square-wave signals 21 and 22. The resultant voltage Udiff is forwarded within the evaluator 4 for further processing for example on a downstream microprocessor 24 which is likewise part of the evaluator 4.

The microprocessor 24 determines a control signal 25 which is

output by the evaluator 4 for further processing in the

railway engineering installation, for example in a switch

tower. The control signal 25 is for example output when the

voltage Udiff exceeds a predetermined threshold value which

may be considered representative of the identified wheel.

Alternatively to the signal routing, shown with dashed arrows

in Fig. 3, via the analytical device 20, the square-wave

signals 21, 22 may also be routed within the evaluator 4

directly to the microprocessor 24, as shown with solid arrows

in Fig. 3, for further processing.

Additionally or also alternatively, the signal UE may be

supplied directly to the microprocessor 25 for level

evaluation. This receive voltage UE would in itself be

sufficient to identify the wheel 7 passing by the sensor

device 2, because the magnetic field and thus also the receive

voltage UE is changed thereby. Evaluation of the receive

voltage UE is thus in itself sufficient to identify the wheel

7.

A further exemplary embodiment of the sensor device 2 and of

the arrangement 6 is described below with reference to

Figures 4 and 5. For simplicity's sake, only the differences

from the exemplary embodiment of Figs. 1-3 will be looked at.

In contrast with the embodiments of Figures 1-3, the sensor device 2 in the embodiment in Figures 4 and 5 comprises two receive oscillating circuits 3 arranged adjacent one another in the longitudinal direction L of the rail. The two receive oscillating circuits 3 are arranged in a common housing 15 and in each case configured in the same way as the receive oscillating circuit 3 of the embodiment of Figs. 1-3.

The two receive oscillating circuits 3, which can also be denoted different channels of the sensor device 2, are separately evaluated by the evaluator 4. Evaluation proceeds in each case in the same manner as shown in Figure 3 for the embodiments of Figures 1-3.

When a wheel 7 of a rail vehicle 8 reaches the sensor device 2 of the embodiment in Figures 4 and 5, the magnetic field 11 which is formed in the entire rail section 26 between the terminal contacts 9 is modified. This magnetic field change which differs timewise between the receive oscillating circuits 3 is also reflected in a timewise different modification of the receive voltage UE of the two receive oscillating circuits 3. On the basis of the time offset, the evaluator 4 can determine, for example by way of the microprocessor 24, the direction of travel of the rail vehicle 8.

The two receive oscillating circuits 3 advantageously make use of the same rail current I s flowing between the terminal contacts 9. Since distance A between the terminal contacts 9 provides sufficient space, further receive oscillating circuits 3 could also be arranged adjacent one another. The number of receive oscillating circuits 3 used is limited solely by the distance A of the rail section 26.

In all the embodiments of Figs. 1-5, the receive oscillating

circuits 3 are fixed relative to the running rail 1.

As already mentioned in the embodiment of Figures 1-3, the

terminal contacts 9 are advantageously connected in a

particularly low-resistance manner to the running rail 1. This

minimizes power losses.

Figure 5 shows the embodiment in Figure 4 in plan view from

above.

Claims (10)

Claims

1. A sensor device for detecting a change in a magnetic field which is brought about by a wheel of a rail vehicle approaching the sensor device on a running rail, with at least one receive oscillating circuit which is configured for producing a receive voltage brought about by the magnetic field, and with at least one evaluator which is connected to the receive oscillating circuit and is configured to evaluate the receive voltage, whe r e in at least one current source which has at least two terminal contacts connectable to the running rail and which is configured to provide a rail current which can be fed into the running rail at the terminal contacts, wherein the magnetic field in a rail section between the terminal contacts can be produced from the rail current fed into the running rail and the receive oscillating circuit is configured to be arrangeable in the rail section between the terminal contacts; and whe r e in the terminal contacts of the current source are arranged on one side of the running rail and the at least one receive oscillating circuit is arranged on the other side of the running rail.

2. The sensor device as claimed in claim 1, whe r e in the evaluator is connected to the current source and is configured to evaluate the rail current.

3. The sensor device as claimed in claim 2, whe r e in the evaluator is configured to evaluate a change in relative phase angles of the receive voltage and rail current.

4. The sensor device as claimed in any one of the preceding claims, wherein the current source is configured to provide the rail current substantially with a resonant frequency of the receive oscillating circuit.

5. The sensor device as claimed in any one of the preceding claims, whe re in the sensor device has at least one signal processing device for the receive voltage and/or the rail current which is configured for level adaptation, filtering and/or amplification.

6. The sensor device as claimed in any one of the preceding claims, whe re in the sensor device has at least two receive oscillating circuits arrangeable adjacent one another in the longitudinal direction of the rail.

7. The sensor device as claimed in one of the preceding claims, whe re in the sensor device has at least one housing in which the at least one receive oscillating circuit is arranged.

8. An arrangement with at least one running rail and with at least one sensor device for detecting a magnetic field change which is brought about by a wheel of a rail vehicle approaching the sensor device on the running rail, wherein the sensor device is arranged on the running rail, whe r e in the sensor device is configured as claimed in any one of the claims 1 to 7.

9. The arrangement as claimed in claim 8, whe r e in a receive coil of the receive oscillating circuit is positioned relative to the running rail in such a way that a receive voltage measurable by the evaluator is produced in each case both with and without a magnetic field change.

10. A method for detecting a change in a magnetic field which

is brought about by a wheel of a rail vehicle approaching the

sensor device on a running rail,

wherein a rail current is fed into a rail section of the

running rail between at least two terminal contacts of a

current source,

a magnetic field is produced from the alternating current and

a receive voltage is produced from the magnetic field in a

receive oscillating circuit, and

the receive voltage and a change in receive voltage brought

about by a magnetic field change are evaluated,

wherein the terminal contacts of the current source are

arranged on one side of the running rail and the at least one

receive oscillating circuit is arranged on the other side of

the running rail.

Siemens Mobility GmbH Patent Attorneys for the Applicant SPRUSON & FERGUSON