AU2018366851A1

AU2018366851A1 - Sensor device

Info

Publication number: AU2018366851A1
Application number: AU2018366851A
Authority: AU
Inventors: Rainer Freise
Original assignee: Siemens Mobility GmbH
Current assignee: Siemens Mobility GmbH
Priority date: 2017-11-14
Filing date: 2018-10-16
Publication date: 2020-04-30
Anticipated expiration: 2038-10-16
Also published as: PL3681777T3; ES2887281T3; WO2019096514A1; CN111315628A; EP3681777A1; AU2018366851B2; DE102017220281A1; EP3681777B1; CN111315628B

Abstract

The invention relates to a sensor device (1) for sensing a change in a magnetic field, which change is caused by an object approaching the sensor device (1) in a longitudinal direction (L) or moving past the sensor device (1) in the longitudinal direction (L). According to the invention, the sensor device (1) comprises at least one receiving coil (10), an AC-fed transmitting coil (30) arranged upstream or downstream of the receiving coil (10) based on the longitudinal direction (L) and two compensation coils (11, 12), one of which is arranged upstream of the transmitting coil (30) and the other of which is arranged downstream of the transmitting coil (30) based on the longitudinal direction (L), the two compensation coils (11, 12) are each permeated by the magnetic field generated by the transmitting coil (30) and are electrically connected in series in such a manner that the voltages induced in the two compensation coils (11, 12) by the magnetic field of the transmitting coil (30) have different signs, and the receiving coil (10) and the two compensation coils (11, 12) are electrically connected in series, wherein the electrical polarity of the coils is selected in such a manner that a magnetic interference field (M) acting on the receiving coil (10) and the two compensation coils (11, 12) induces a voltage in the receiving coil (10) with a sign which differs from that in the two compensation coils (11, 12).

Description

Sensor device

The invention relates to sensor devices for sensing magnetic field changes, in particular for detecting objects approaching the sensor device or passing same.

A sensor device based on the sensing of a magnetic field change resulting from an iron wheel of a railroad vehicle traveling over a track is described in the German published patent application DE 101 37 519 Al for example.

In the field of railroad technology, magnetic interference fields are produced to a significant degree by electric rail currents, which are injected in to the track by electric railroad vehicles or respectively electric locomotives.

The object underlying the invention is to specify a sensor device which is as insensitive as possible to magnetic interference fields, and also enables reliable object identification even in the case of an interference field influence .

According to the invention this object is achieved by a sensor device with the features according to claim 1. Advantageous embodiments of the inventive sensor device are specified in dependent claims.

Accordingly, the invention provides that the sensor device comprises at least one receiving coil, an AC-fed transmitting coil arranged upstream or downstream of the receiving coil

PCT/EP2018/Ο78139 / 2017P18986WO based on the longitudinal direction of the sensor device, and two compensation coils, one of which is arranged upstream and the other downstream of the transmitting coil based on the longitudinal direction, the two compensation coils are each permeated by the magnetic field generated by the transmitting coil and are electrically connected in series in such a manner that the voltages induced in the two compensation coils by the magnetic field of the transmitting coil have different signs, and the receiving coil and the two compensation coils are electrically connected in series, wherein the electrical polarity of the coils is selected in such a manner that a magnetic interference field acting on the receiving coil and the two compensation coils induces a voltage in the receiving coil with a sign which differs from that in the two compensation coils.

A fundamental advantage of the inventive sensor device can be seen in the fact that the arrangement of the two compensation coils, the electrical connection of the compensation coils to the receiving coil, and the resulting variability of the voltages make it possible to completely or at least substantially suppress, during signal sensing, an interference field (e.g. a magnetic field of a rail current) which is permeating the coils.

In the case of an established magnetic field change the sensor device preferably generates an object identification signal which indicates an object approaching or moving past. The object identification signal can be generated for example whenever falling electric voltage at the series connection of the receiving coil and the compensation coils reaches or exceeds a predetermined threshold or changes abruptly.

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The longitudinal axis of the transmitting coil preferably lies parallel or at least essentially parallel to the longitudinal direction of the sensor device, or itself forms the longitudinal direction of the sensor device.

The longitudinal axis of the receiving coil and that of the two compensation coils are preferably each aligned perpendicular or at least essentially perpendicular to the longitudinal axis of the transmitting coil.

The two compensation coils are preferably each arranged and/or dimensioned in such a manner that the magnetic field generated by the transmitting coil induces equally large voltages with different signs in the two compensation coils (corresponding to a phase shift of 180°).

The two compensation coils preferably have the same construction and are arranged in mirror symmetry with regard to the transmitting coil.

It is also regarded as advantageous if the receiving coil and the two compensation coils are arranged and/or dimensioned in such a manner that the voltage induced in the receiving coil by the magnetic interference field is as large as the sum voltage formed by the voltages induced in the two compensation coils, and the voltage induced by the interference field has a value of zero or at least approximately zero at the series connection consisting of the receiving coil and the two compensation coils.

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With regard to the electrical connection of the coils, it is considered advantageous if at least one capacitor is connected in parallel with the series connection of the two compensation coils and together with same forms a compensating oscillating circuit, at least one capacitor is connected in parallel with the receiving coil and together with same forms a receiving oscillating circuit, and the resonance frequency of the compensating oscillating circuit and the resonance frequency of the receiving oscillating circuit are the same or the resonance frequency range of the compensating oscillating circuit at least overlaps with the resonance frequency range of the receiving oscillating circuit.

The sensor device can be implemented as two-channel. In this case the aforesaid two compensation coils and the aforesaid receiving coil preferably form a first channel of the sensor device. Two further compensation coils and a further receiving coil preferably form a second channel of the sensor device, with one of the two further compensation coils being arranged upstream and the other downstream of the transmitting coil, and the transmitting coil being arranged between the two receiving coils.

Additionally, provision can be made advantageously for the compensation coils or at least one of them and/or the receiving coil(s) to each be formed out of two or more coil sections which are electrically connected to each other.

Moreover the invention relates to an arrangement with a rail, in particular a railroad rail, on which a sensor device as described above is mounted.

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It is advantageous if the sensor device is mounted on the rail in such a manner that the longitudinal direction of the sensor device and/or the longitudinal direction (or respectively the longitudinal axis) of the transmitting coil of the sensor device corresponds to the longitudinal direction of the rail.

The receiving coil or receiving coils and the transmitting coil preferably lie in the same horizontal plane. The compensation coils preferably likewise lie in a horizontal plane, whether the same plane as the transmitting coil or another plane, in particular parallel to same.

A preferred embodiment provides for the spacing of the compensation coils from the rail head to be greater than the spacing of the receiving coil or receiving coils. It is advantageous in an embodiment of this type if the compensation coils lie in a horizontal plane that lies at a deeper level than the horizontal plane in which the receiving coil or receiving coils and the transmitting coil lie.

An exemplary embodiment regarded as particularly advantageous provides for the receiving coil or receiving coils and the compensation coils to each be inclined compared to the horizontal, or respectively the longitudinal axes of the said coils compared to the vertical, wherein the receiving coil or receiving coils face toward the rail head and the compensation coils face away from the rail head.

The invention is explained in detail below on the basis of exemplary embodiments; in this respect the following show by way of example:

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Figure 1 A railroad rail on which an exemplary embodiment of a single-channel sensor device is mounted,

Figure 2 The electric circuitry of the components of the sensor device shown in Figure 1 in the form of an electrical circuit diagram, and

Fig. 3-6 Exemplary embodiments of two-channel sensor devices which are mounted on a rail.

For the sake of clarity, the same reference symbols are always used for identical or comparable components in the figures.

Figure 1 shows an exemplary embodiment of a single-channel sensor device 1 which is suitable for sensing magnetic field changes and for sensing objects such as iron wheels of railroad vehicles for example. In the event of identifying an object the sensor device 1 generates an object identification signal.

The sensor device 1 comprises a receiving coil 10, two compensation coils 11, 12, and a transmitting coil 30. The transmitting coil is driven with the aid of an AC voltage Us (see Fig. 2); a capacitor C can be connected in parallel with the transmitting coil (see Fig 2).

The receiving coil 10 can be arranged upstream or downstream of the transmitting coil 30 - based on the longitudinal direction L of the sensor device 1. In the exemplary embodiment shown in Figure 1 the receiving coil 10 is located downstream of the transmitting coil 30 when viewed in the longitudinal direction L. The longitudinal direction L30 of

PCT/EP2018/Ο78139 / 2017P18986WO the transmitting coil 30 defines the longitudinal direction L of the sensor device.

One of the two compensation coils 11 and 12 - again based on the longitudinal direction L - is positioned upstream and the other downstream of the transmitting coil 30.

The sensor device 1 is attached on a side wall of a rail 40 which is suitable for guiding a railroad vehicle, and can be a railroad rail for example. The sensor device 1 is located below the rail head 50 of the rail 40. The components of the sensor device 1 are preferably accommodated in a housing 70 which is fixed, for example bolted on, to the side wall of the rail 40.

Moreover Figure 1 shows a magnetic interference field M which can be produced for example by an electric rail current flowing through the rail 40. A rail current of this type usually occurs when an electrically driven railroad vehicle travels over the rail 40.

In the case of the exemplary embodiment shown in Figure 1 the longitudinal axis L10 of the receiving coil 10, the longitudinal axis Lil of the compensation coil Lil, and the longitudinal axis L12 of the compensation coil 12 is aligned perpendicular or at least essentially perpendicular (+ 15°) to the longitudinal direction L of the sensor device 10.

With the aim of detecting vehicles traveling on the rail 40 the arrangement of the sensor device 1 on the rail 40 is selected in such a manner that the longitudinal direction L of the sensor device 1 and therefore the longitudinal direction

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LIO of the transmitting coil 30 lies parallel to the longitudinal direction of the rail 40.

The magnetic field generated by the transmitting coil 30 preferably generates equally sized voltages with different signs in the two compensation coils. The different signs of the voltages are already produced by the circumstance that one of the compensation coils is arranged upstream and the other downstream of the transmitting coil 30, and to this degree the direction of the magnetic field in the two compensation coils 11 and 12 is different. Equal-sized voltages induced by the magnetic field of the transmitting coil 30 can be achieved particularly easily if the two compensation coils 11 and 12 have the same construction and are arranged in mirror symmetry with regard to the transmitting coil 30.

To prevent errors in detection, or respectively to minimize the influence of the magnetic interference field M on the generation of an object identification signal, the arrangement and dimensioning of the receiving coil 30 is coordinated with the arrangement and dimensioning of the two compensation coils 11 and 12, and in fact in such a manner that the voltage induced in the receiving coil 10 by the magnetic interference field M is as large as the sum voltage induced in the two compensation coils 11 and 12 by the magnetic interference field M, and moreover has the opposite sign.

The two compensation coils 11 and 12 preferably lie in the same plane, which is identified in Figure 1 by the reference symbol 80. The recording coil 10 and the transmitting coil 30 preferably likewise lie in a common plane, which bears the reference symbol 90 in Figure 1. In the exemplary embodiment

PCT/EP2018/Ο78139 / 2017P18986WO shown in Figure 1 the plane 80 lies below the plane 90 in spatial terms. In other words the distance of the compensation coils 11 and 12 from the head of the rail 50 is greater than the distance of the receiving coil 10 and the transmitting coil 30 from the head of the rail in the exemplary embodiment shown in Figure 1.

Figure 2 specifically shows the electric circuitry for the coils of the sensor device 1 in detail. It can be seen that the two compensation coils 11 and 12 are connected electrically in series, and in fact in such a manner that the voltages induced in the two compensation coils 11 and 12 by the magnetic field of the transmitting coil 30 have different signs. The magnetic field of the transmitting coil 30 does not result in a sum voltage (compensation voltage) Ucompl at the series connection of the two compensation coils 11 and 12 therefore .

Moreover Figure 2 shows that the receiving coil 10 and the series connection made up of the two compensation coils 11 and 12 are likewise electrically connected in series, with the electrical polarity of the coils being selected in such a manner that a magnetic interference field M acting upon the receiving coil 10 and the two compensation coils 11 and 12 (see Figure 1) induces a voltage with a different sign in the receiving coil 10 than in the two compensation coils 11 and

12. It is advantageous if the voltage Uel induced in the receiving coil 10 by the interference field M is as large as the sum voltage Ucompl at the series connection made up of the two compensation coils 11 and 12; in this case the total voltage U1 through the magnetic field M is zero or at least approximately zero.

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U1 = Ucompl + Uel ~ 0

The variation in the signs of the voltages Ucompl and Uel - in the case of induction of a voltage by the magnetic interference field M - is achieved by the electrical connection of the coils relative to each other as shown in Figure 2.

A first capacitor Cl is preferably situated in parallel with the receiving coil 10, and a second capacitor C2 is preferably situated in parallel with the series connection made up of the compensation coils 11 and 12. The first capacitor Cl forms, together with the receiving coil 10, a receiving oscillating circuit SE with a resonance frequency fl. The second capacitor C2 forms, together with the series connection made up of the two compensation coils 11 and 12, a compensation oscillating circuit SK with a resonance frequency f2.

With the aim of creating a good compensation effect by the two compensation coils 11 and 12, it is advantageous if the resonance frequency fl of the receiving oscillating circuit SE and the resonance frequency f2 of the compensation oscillating circuit SK are the same size or the resonance frequency ranges of the two oscillating circuits at least overlap.

To damp the oscillating circuits SE and SK, resistances R1 or respectively R2 can be connected in series with the capacitors Cl and C2.

The total voltage U1 at the series connection of the coils 10, 11 and 12 can be evaluated for generating an object

PCT/EP2018/Ο78139 / 2017P18986WO identification signal: for example the object identification signal can be generated when the total voltage U1 changes abruptly or reaches or exceeds a predetermined threshold value .

Figure 3 shows an exemplary embodiment of a two-channel sensor device 1 which is mounted on a rail 40. In contrast to the sensor device 1 shown in Figure 1, the sensor device 1 shown in Figure 3 has a two-channel configuration and has two receiving channels A and B. The receiving channel A is formed by the receiving coil 10 and the two compensation coils 11 and 12, whose arrangement, mode of functioning, and electrical connection have already been explained in conjunction with Figures 1 and 2.

Channel B of the sensor device 1 is formed by means of a further receiving coil 20 and also two further compensation coils 21 and 22, whose arrangement is in mirror symmetry to the arrangement of the coils in channel A. The implementations relating to the receiving coil 10 and the compensation coils 11 and 12 in conjunction with Figures 1 and 2 therefore apply correspondingly to the second receiving coil 20 and the further compensation coils 21 and 22.

In the exemplary embodiment shown in Figure 3 the compensation coils 11, 12, 21, and 22 lie in the same plane 80, and in fact one behind the other when viewed in the longitudinal direction L of the sensor device 1 or respectively in the longitudinal direction of the rail 40.

Figure 4 shows a further exemplary embodiment of a two-channel sensor device 1 which is being traveled over by a wheel rim

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130 of an iron wheel 120. The sensor device 1 shown in Figure 4 has the components already explained in conjunction with Figure 3, that is to say a transmitting coil 30, two receiving coils 10 and 20, and also four compensation coils 11, 12, 21, and 22. With regard to the mode of functioning of the coils, the comments made in conjunction with Figures 1 to 3 for the exemplary embodiment shown in Figure 4 apply correspondingly.

In contrast to the exemplary embodiment shown in Figure 3 the compensation coils in the embodiment variant shown in Figure 4 lie in pairs adjacent to each other (when viewed along the longitudinal direction of the rail). Thus it can be seen that the compensation coils 11 and 21 do in fact lie in the same plane 80, but the spacing of the compensation coil 11 from the rail 40 is smaller than the spacing of the compensation coil

21. The compensation coil 11 can therefore be designated as the inner compensation coil and the compensation coil 21 as the outer compensation coil. The compensation coils 12 and 22 are arranged adjacent to each other in a similar manner.

Figure 5 shows an exemplary embodiment of a two-channel sensor device 1 in which the planes 80 and 90, in which the receiving coils and the compensation coils are situated, are each inclined compared to the horizontal; the longitudinal axes of the receiving coil and the compensation coils are therefore inclined compared to the vertical. Thus it can be seen in Figure 5 that the receiving coil 10 or respectively its longitudinal axis L10 is facing toward the rail head 50 of the rail 40, whereas the compensation coils 11 and 21 or respectively their the longitudinal axes Lil and L21 are facing away from the rail head 50. The receiving coil 20, which is not shown in Figure 5, and the compensation coils 12

PCT/EP2018/Ο78139 / 2017P18986WO and 22, likewise not shown, are likewise arranged inclined in a corresponding manner.

The inclination of the receiving coils 10 and 20 toward the wheel flange or respectively rail head 50 results in a particularly high level of sensitivity of the receiving coils being achieved; the opposite inclination of the compensation coils 11, 12, 21, and 22 reduces the influence of the rail head 50 on the compensation coils.

Figure 6 shows an exemplary embodiment of a two-channel sensor device 1 in which the compensation coils 11, 12, 21, and 22 are each distanced further from the transmitting coil 30 than the receiving coils 10 and 20. In the embodiment shown in Figure 6 all the coils 10, 11, 12, 20, 22, and 30 can be arranged in the same plane and each have the same vertical spacing from the rail head 50 of the rail 40. In the exemplary embodiment shown in Figure 6 the coils 10, 11, and 12 belong to one receiving channel and the coils 20, 21, and 22 to a second receiving channel.

Although the invention has been closely illustrated and described in detail by means of preferred exemplary embodiments, the invention is not limited by the examples disclosed, and other variations can be derived from same by a person skilled in the art without departing from the scope of protection of the invention.

Claims

Claims

1. A sensor device (1) for sensing a change in a magnetic field, which change is caused by an object approaching the sensor device (1) in a longitudinal direction (L) or moving past the sensor device (1) in the longitudinal direction (L), characterized in that

- the sensor device (1) comprises at least one receiving coil (10), an AC-fed transmitting coil (30) arranged upstream or downstream of the receiving coil (10) based on the longitudinal direction (L) and two compensation coils (11,

12), one of which is arranged upstream of the transmitting coil (30) and the other of which is arranged downstream of the transmitting coil (30) based on the longitudinal direction (L) ,

- the two compensation coils (11,12) are each permeated by the magnetic field generated by the transmitting coil (30) and are electrically connected in series in such a manner that the voltages induced in the two compensation coils (11, 12) by the magnetic field of the transmitting coil (30) have different signs, and

- the receiving coil (10) and the two compensation coils (11, 12) are electrically connected in series, wherein the electrical polarity of the coils is selected in such a manner that a magnetic interference field (M) acting on the receiving coil (10) and the two compensation coils (11, 12) induces a voltage in the receiving coil (10) with a sign which differs from that in the two compensation coils (11, 12).
2. The sensor device (1) as claimed in claim 1, characterized in that

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- the longitudinal axes (LIO, Lil, L21) of the receiving coil (10) and the two compensation coils (11, 12) are each aligned perpendicular or at least essentially perpendicular to the longitudinal axis (L30) of the transmitting coil (30), and

- the longitudinal axis (L30) of the transmitting coil (30) is aligned parallel or at least essentially parallel to the longitudinal direction (L) of the sensor device (1).
3. The sensor device (1) as claimed in one of the preceding claims, characterized in that the two compensation coils (11, 12) are each arranged and/or dimensioned in such a manner that the magnetic field generated by the transmitting coil (30) induces equally large voltages with different signs in the two compensation coils (11, 12).
4. The sensor device (1) as claimed in one of the preceding claims, characterized in that the two compensation coils (11, 12) have the same construction and are arranged in mirror symmetry with regard to the transmitting coil (30) .
5. The sensor device (1) as claimed in one of the preceding claims, characterized in that the receiving coil (10) and the two compensation coils (11, 12) are arranged and/or dimensioned in such a manner that - the voltage induced in the receiving coil (10) by the magnetic interference field (M) is as large as the sum voltage formed by the voltages induced in the two compensation coils (11, 12), and

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- the voltage induced by the interference field (M) has a value of zero or at least approximately zero at the series connection consisting of the receiving coil (10) and the two compensation coils (11, 12) .
6. The sensor device (1) as claimed in one of the preceding claims, characterized in that at least one capacitor (C2) is connected in parallel with the series connection of the two compensation coils (11, 12) and together with same forms a compensating oscillating circuit (SK) , at least one capacitor (Cl) is connected in parallel with the receiving coil (10) and together with same forms a receiving oscillating circuit (SE), and the resonance frequency of the compensating oscillating circuit (SK) and the resonance frequency of the receiving oscillating circuit (SE) are the same or the resonance frequency range of the compensating oscillating circuit (SK) at least overlaps with the resonance frequency range of the receiving oscillating circuit (SE).
7. An arrangement as claimed in one the preceding claims characterized in that at least one of the compensation coils (11, 12) and/or at least one receiving coil (10) is formed out of two or more coil sections which are electrically connected to each other.
8. The sensor device (1) as claimed in one of the preceding claims, characterized in that

- the sensor device (1) is two-channel,

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- two compensation coils (11, 12) and the receiving coil (10) form a first channel of the sensor device (1),

- two further compensation coils (21, 22) and a further receiving coil (20) form a second channel of the sensor device (1) ,

- one of the two further compensation coils (21, 22) is arranged upstream and the other downstream of the transmitting coil (30), and

- the transmitting coil (30) is arranged between the receiving coils (10. 20).
9. An arrangement with a rail (40), in particular a railroad rail, characterized in that the sensor device (1) is a sensor device (1) as claimed in one of the preceding claims and the sensor device (1) is mounted on the rail (40) in such a manner that the longitudinal direction (L) of the sensor device (1) corresponds to the longitudinal direction of the rail.
10. An arrangement as claimed in claim 9, characterized in that the receiving coil (10) or receiving coils (10, 20) and the transmitting coil (30) lie in the same horizontal plane.
11. The arrangement as claimed in one of the preceding claims 9 to 10, characterized in that the compensation coils (11. 12) lie in the same horizontal plane .

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12. The arrangement as claimed in one of the preceding claims 9 to 11 characterized in that the spacing of the compensation coils (11, 12) from the rail head is greater than the spacing of the receiving coil (10) or receiving coils (10, 20) from the rail head.
13. The arrangement as claimed in one of the preceding claims 9 to 12, characterized in that the compensation coils (11, 12) lie in a horizontal plane (80) that lies at a deeper level than the horizontal plane (90) in which the receiving coil (10) or receiving coils and the transmitting coil (30) lie.
14. The arrangement as claimed in one of the preceding claims 9 to 13, characterized in that the receiving coil (10) or receiving coils and the compensation coils (11, 12) are each inclined relative to the horizontal, or respectively their longitudinal axes (L10, Lil, L21) relative to the vertical, wherein the receiving coil (10) or receiving coils face toward the rail head and the compensation coils (11, 12) face away from the rail head.