Transmitter device, sensor device and method for sensing a magnetic field change

Abstract

A transmitter device for a sensor device detects a magnetic field change caused by an object approaching or moving past the sensor device, in particular by a wheel of a rail vehicle. The transmitter device has at least two alternating-current-fed transmitter oscillating circuits. In order to implement error disclosure of the sensor device in a particularly simple manner, the at least two transmitter oscillating circuits are formed in such a way that the resonance frequencies thereof are different from each other. A sensor device and a method for detecting a magnetic field change are also provided.

Claims

1. A sensor device for detecting a magnetic field change caused by an object approaching or moving past the sensor device, the sensor device comprising: at least one transmitter device including at least two alternating-current-fed transmitter oscillating circuits for forming a transmitter frequency of said at least one transmitter device, said at least two transmitter oscillating circuits being constructed to have resonance frequencies being different than each other; at least one monitoring device for determining the transmitter frequency of said at least one transmitter device and for checking whether the determined transmitter frequency is in a predetermined frequency range; and at least one receiver device.

2. The sensor device according to claim 1, wherein the object is a wheel of a rail vehicle.

3. The sensor device according to claim 1, wherein said monitoring device is configured for outputting a warning signal when the determined transmitter frequency is outside the predetermined frequency range.

4. The sensor device according to claim 1, wherein the sensor device is a wheel sensor for detecting a magnetic field change caused by a wheel moving past the wheel sensor on a rail in a direction of movement along a longitudinal direction of the rail.

5. A method for detecting a magnetic field change caused by an object approaching or moving past a sensor device in a direction of movement of the sensor device, the method comprising the following steps: using at least two alternating-current-fed transmitter oscillating circuits to form a transmitter frequency of a transmitter device; forming the transmitter frequency from at least two different resonance frequencies of the at least two transmitter oscillating circuits; forming each of the at least two resonance frequencies with a frequency outside a predetermined frequency range of the transmitter frequency; and determining the transmitter frequency and generating a warning signal when the determined transmitter frequency is outside the predetermined range.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention will be explained in the following with reference to the accompanying drawing.

(2) The single FIGURE shows a schematic illustration of an exemplary embodiment of an inventive sensor device.

DESCRIPTION OF THE INVENTION

(3) A sensor device 1 of the embodiment illustrated by way of example in the FIGURE comprises a transmitter device 2 and a receiver device 3. The sensor device 1 is arranged on both sides of a rail 4 which is part of a railroad engineering system (not shown) and is driven on by at least one rail vehicle (not shown) in a direction of movement along the longitudinal direction of the rail.

(4) The transmitter device 2 has two transmitter oscillating circuits 5.1, 5.2 connected in parallel, an electronic circuit 6 and a monitoring device 7. These components of the sensor device 1 are electrically connected to each other by electrical connections 8, which are shown only simplistically in the FIGURE for reasons of clarity. In the sensor device 1 illustrated by way of example in the FIGURE the two transmitter oscillating circuits 5.1, 5.2 are arranged in a housing 9 and the electronic circuit 6 and the monitoring device 7 in a further housing 10. Of course, the transmitter device 2 could be also completely arranged in a shared housing. The transmitter oscillating circuits 5.1, 5.2 each have an inductance 11.1, 11.2, for example a coil, and a capacitance 12.1, 12.2, for example a capacitor. The transmitter oscillation circuits 5.1, 5.2 are designed as parallel oscillating circuits.

(5) The receiver device 3 has two receiver oscillating circuits 13.1, 13.2, and an evaluation device (not shown). The receiver oscillating circuits 13.1, 13.2 are arranged in a housing 14 opposite the transmitter oscillating circuits 5.1, 5.2 on the other side of the rail 4. The receiver device 3 could alternatively have, for example, even just one receiver oscillating circuit 13.

(6) The mode of operation of the inventive sensor device 1 is described below.

(7) During operation, the electronic circuit 6 of the transmitter device 2 generates an alternating current with a transmitter frequency f.sub.s of, for example, 50 kHz. This alternating current feeds, via the electrical connections 8, the two transmitter oscillating circuits 5.1, 5.2 connected in parallel. According to the invention, the two transmitter oscillating circuits 5.1, 5.2 are configured so they have mutually different resonance frequencies f.sub.r. The resonance frequencies f.sub.r are configured so they are each outside a predetermined range of 50 kHz+/3 kHz. In the exemplary embodiment in the FIGURE, for example, the transmitter oscillating circuit 5.1 has a resonance frequency of 45 kHz and the transmitter oscillating circuit 5.2 a resonance frequency of 55 kHz. The two transmitter oscillating circuits 5.1, 5.2 and the electronic circuit 6 jointly form a self-oscillating oscillator circuit 15. Due to the parallel connection of the transmitter oscillating circuits 5.1, 5.2, the transmitter frequency f.sub.s is established as the mean of the mutually different resonance frequencies f.sub.r of the two transmitter oscillating circuits 5.1, 5.2. In the embodiment illustrated by way of example in the FIGURE the transmitter frequency f.sub.s is therefore 50 kHz. The transmitter frequency f.sub.s is an operating frequency of the transmitter device 2. During operation, the monitoring device 7 determines the transmitter frequency f.sub.s of the transmitter device 2 and checks whether the determined transmitter frequency f.sub.s is in the predetermined frequency range of 50 kHz+/3 kHz here. If the determined transmitter frequency f.sub.5 is outside the predetermined frequency range, the monitoring device 7 outputs a warning signal.

(8) If in the inventive transmitter device 2 one of the transmitter oscillating circuits 5.1, 5.2 fails as a result of a fault, such as, for example a cable or wire breakage or a component failure, the transmitter frequency f.sub.s of the oscillator circuit 15 inevitably changes because it is now determined only by the one remaining transmitter oscillating circuit 5.1, 5.2. The one transmitter oscillating circuit 5.1, 5.2 pulls the transmitter frequency f.sub.s outside the predetermined range since the transmitter frequency f.sub.s now matches the resonance frequency f.sub.r of the remaining transmitter oscillating circuit 5.1, 5.2. This change in the transmitter frequency f.sub.s outside the predetermined range is detected by the monitoring device 7 and the corresponding warning signal indicates the fault in the transmitter device 2. The warning signal can, for example, be transmitted to a control center (not shown) of the railroad engineering system which initiates appropriate measures.

(9) Due to the alternating current generated by the oscillator circuit 15 of the transmitter device 2, a magnetic field is generated which induces a current in the receiver oscillating circuits 13.1, 13.2 of the receiver device 3 by way of the magnetic coupling 16. An object moving past the rail 4, for example the wheel of a rail vehicle, influences this magnetic coupling 16, so the magnetic field change can be detected on the receiver side by the evaluation device (not shown) of the receiver device 3.

(10) The transmitter device 2 and receiver device 3 are each designed in the exemplary embodiment of the FIGURE with two transmitter oscillating circuits 5.1, 5.2 and two receiver oscillating circuits 13.1, 13.2. Therefore, the sensor device 1 is also referred to as two-channel, with each transmitter oscillating circuit 5.1, 5.2 or receiver oscillating circuit 13.1, 13.2 forming one channel respectively. The inventive transmitter device 2 in the FIGURE has two channels but could of course also have more channels.