EP3569467A1 - Sensor for detecting metal parts and method for reducing a magnetic field - Google Patents

Abstract

Sensor for detecting metal parts, in particular metal or partially metal wheels of a rail vehicle, with an electrical oscillating circuit which has at least one sensor capacitance and a sensor coil that includes a coil core and generates a magnetic field, the coil core of the sensor coil, based on its longitudinal axis, being approximately in is arranged at an orthogonal angle to a direction of movement of the metallic or partially metallic wheels of the rail vehicle in order to weaken a magnetic field emanating from the rail vehicle. The use of at least two such sensors and a method for weakening a magnetic field emanating from a rail vehicle are also specified.

Description

The present invention relates to a sensor for detecting metal parts, in particular metal or part metallic wheels of a rail vehicle, a use of at least two such sensors and a method for attenuating an emanating from a rail vehicle magnetic field.

In general, devices for detecting metal parts, in particular for detecting metallic or semi-metallic wheels of rail vehicles, are realized with the aid of inductive sensors. This requires the highest level of security despite sporadic application. An example of such an area of application is rail transport. In the following, reference will be made to the use of such sensors or such a method in railway traffic. However, there is no restriction on this area of application.

In the field of railway traffic, it is customary for a sensor for detecting metal parts, in particular metal or part metallic wheels of a rail vehicle, to be parallel in the rail longitudinal direction, ie parallel to the direction of movement the wheels of the rail vehicle, is arranged. Such a sensor provides high availability signals, which are usually routed via a cable in an indoor facility and processed accordingly. As a result, functions, such as the presence of a rail vehicle, the direction of travel detection or a track vacancy in the form of an axis count can be realized.

It is also common for each sensor to consist of a sensor coil and an oscillator circuit. The sensor coil forms a resonant circuit with a capacitor and builds up an alternating magnetic field in its environment. A penetrating into the effective range of the sensor coil metallic part of a railway wheel dampens the resonant circuit, since this is withdrawn by the iron of the railway wheel energy through eddy current losses. This has the consequence that the voltage amplitude or the voltage frequency of the resonant circuit changes, which is converted into a change in the current consumption of the sensor. This measuring signal is conducted via a two-wire cable into the internal system of a security system where it is processed or processed for processing.

The mounting position of the sensor is predetermined by the geometry of the rail or by the railway wheel within narrow limits. Irrespective of this, however, a problem arises that magnetic fields can also be emitted by the rail vehicle with such a high intensity that a voltage is induced in the sensor coil. This process can lead to a condition in the electronics that falsely passes on the presence of a wheel to the higher-level evaluation electronics. There, this leads to incorrect information that can interfere with the operation of the railway network. Such magnetic fields emitted by the rail vehicle are generated, for example, by eddy current brakes, magnetic rail brakes or a strong current consumption by the drive units of the rail vehicles.

It is known, for example, from the prior art document DE 199 15 597 A1 an arrangement of an eight-coil, which is aligned in the direction of travel of the rail vehicle. The two sub-coils of the eight-coil are connected in such a way that a magnetic field which is emitted from a distance significantly larger than the extension of the eight-coil, is already compensated in this.

The state of the art document DE 101 37 519 A1 tries to solve the problem described above by an additional coil, which is embedded in the actual transmitting or receiving coil.

The WO 2010/052081 A1 describes an arrangement in which a coil is the transmitting or receiving coil and a second coil is used exclusively for the compensation. This second coil is arranged at least one third of the coil diameter of the transmitting or receiving coil below.

The DE 10 2009 053 257 A1 discloses an arrangement of sensor and compensation coil with a total of three coils.

However, there have been various disadvantages in the prior art. Thus, the magnetic field emitted by the rail vehicle either hits the sensor coil at different times or a compensation arrangement for an induced voltage is very demanding to realize.

When a wheel of a rail vehicle passes over the sensor coil, first the outer and then the middle coil is influenced by the magnetic field. Only when both coils are flooded with the magnetic field emitted by the rail vehicle, it comes to an optimal compensation. Another disadvantage of the prior art is that compensation coils are usually mounted below the actual transmitting or receiving coils, whereby the compensation coils do not experience the same intensity of the magnetic field emitted by the rail vehicle as the transmitting or receiving coils. This is because as the distance from the source increases, the magnetic field becomes weaker. As a result, a complete compensation is prevented and an interference voltage remains. Another disadvantage is shown by very demanding to realize coil structures, which in particular require a lot of space, especially for the railway sector. Also, with the complicated coil designs, the drawback already described is that the coil is not exposed to the same magnetic field at any time during the passage of a wheel of a rail vehicle.

It is therefore an object of the present invention to eliminate or at least minimize the disadvantages known from the prior art.

This object is achieved by a sensor according to claim 1. Accordingly, a sensor for detecting metal parts, in particular of metal or part metallic wheels of a rail vehicle, is provided with an electrical resonant circuit having at least one sensor capacitance and a coil core comprehensive and a magnetic field generating sensor coil, wherein the coil core of the sensor coil, based on the longitudinal direction of which is approximately at an orthogonal angle to a direction of movement of the metal or part metallic wheels of the rail vehicle in order to attenuate a magnetic field emanating from the rail vehicle.

The term "approximately in an orthogonal angle" is understood to mean, in particular, an arrangement of the coil core of the sensor coil at an angle of 70 ° to 110 ° to a direction of movement of the metallic or semi-metallic wheels of the rail vehicle, this arrangement being based on the longitudinal axis of the coil core , Preferably, this arrangement is carried out at an angle of 80 ° to 100 °, more preferably 85 ° to 95 °. It is also possible that it is an orthogonal angle in the mathematical sense, ie a right-angled (90 °) angle.

The sensor according to the invention offers the advantage that the magnetic field emitted by a rail vehicle is attenuated. This prevents induction of a voltage induced in the sensor coil by such a magnetic field. This is achieved by arranging the coil core of the sensor coil approximately at an orthogonal angle to the direction of movement of the metallic or semi-metallic wheels of the rail vehicle. As a result, the magnetic fields emanating from the rail vehicle are weakened at the moment they reach the sensor coil due to the coil structure and the coil positioning. The construction of the sensor coil also ensures that only the magnetic fields emanating from the rail vehicle are compensated. The magnetic field generated by the sensor coil, which is influenced by the metallic or partially metallic wheels and is used by the sensor for detecting the presence of the wheel of a rail vehicle, is not impaired by the article according to the invention. In particular, the present invention is based on the finding that the magnetic fields emitted by the rail vehicle are in good approximation at each location of the rail contact have the same direction and similar intensities. The generators of this magnetic field emitted by the rail vehicle are at a distance from the sensor coil which is large compared to the dimensions of the sensor coil. This is used both in the construction and in the approximately orthogonal positioning of the sensor coil, which ensures the compensation of the voltage induced by the magnetic field emitted by the rail vehicle.

Preferably, the bobbin consists of highly permeable material. A highly permeable material is understood below to mean a material which has a relative permeability greater than 10. As a result, using a material known in the prior art, the advantage is achieved that a cost-effective, yet high-quality spool core is available.

Likewise, it has proved to be advantageous that the coil core is a ferrite core. As a result, for example, a soft magnetic coil core can be realized.

In functional terms, it has proved to be advantageous that the coil core along the longitudinal axis encloses a surface and has at its ends at least two end faces from which the majority of the magnetic field enters and / or exits. An advantage of this is that the coil core is not closed, whereby the largest part of the magnetic flux enters and exits through the at least two end faces on the coil core. Since the bobbin is disposed at an approximately orthogonal angle to the direction of movement of the metal or part metallic wheels of the rail vehicle, the magnetic field in the air above the sensor coil propagates, directed where the metallic or semi-metallic wheel of a rail vehicle to be detected is expected. This ensures that hit at any time, including during the passage of a wheel of a rail vehicle, the magnetic fields emitted by the rail vehicle at the same time on the two end faces of the sensor coil. As a result, a voltage is induced, which, however, due to different signs, cancel each other out.

In a further embodiment, the coil core has a U-shape, an E-shape, or an F-shape. By such a shape can in the state of Technically known coil cores are used in the sensor of the present invention.

Advantageously, the spool core, due to its shape, at least two legs. Through these two legs, the excitation direction of the sensor coil can be accurately adjusted.

In a further embodiment, the windings of the sensor coil are wound asymmetrically around the legs. This is particularly advantageous if the magnetic fields emitted by the rail vehicle impinge asymmetrically on the legs of the coil core. As a result, a possible induced voltage, which occurs due to the asymmetrical emitted magnetic fields, can be further reduced.

It is also possible that the sensor coil has different winding numbers at different points of the coil core. As a result, inter alia, the advantages of the preceding embodiment can be achieved. In particular, it is thereby possible that a magnetic field emitted by the rail vehicle, which induces a voltage in the sensor coil, is further attenuated.

It is also possible that a winding is applied along the spool core. This achieves a simple and inexpensive possibility of production known in the art.

In a further embodiment, at least one winding of the sensor coil is arranged at an arbitrary location of the coil core. This makes it possible in particular for the purpose of further signal processing, the winding can be arranged at any point of the bobbin without affecting the functionality of the sensor.

Also, it has proven to be advantageous in functional terms that the legs are dimensioned differently. Since the magnetic fields emitted by the rail vehicle are more in the vicinity of a rail head, the emitted magnetic field is asymmetrical and consequently also asymmetrically impinges on the legs of the sensor coil. As a result, it may happen that a residual voltage can be measured on the sensor coil even after the compensation, which can continue to disturb the function of the electronics. By doing that, the thighs are dimensioned differently, the residual voltage can be reduced to a minimum, or reduced to the value zero, so as not to affect the detection of metal parts, in particular metallic or semi-metallic wheels of a rail vehicle.

In a further embodiment, the sensor is installed in a housing, wherein the magnetic field of the sensor coil is dimensioned such that it goes out of the housing. As a result, in particular, the sensor can be protected against environmental influences, damage or vandalism, and nevertheless effect a reliable detection of metal parts, in particular metallic or semi-metallic wheels of a rail vehicle.

The problem posed at the beginning is also solved by the use of at least two sensors according to one of the preceding exemplary embodiments for determining a direction of movement of a rail vehicle. This achieves the advantages of the sensor.

The object is also achieved according to the invention by a method for attenuating a magnetic field emanating from a rail vehicle, comprising the step of attaching a sensor coil of an electrical oscillating circuit, the sensor coil having a coil core which, with respect to its longitudinal axis, approximately at an orthogonal angle a movement direction of the metallic or semi-metallic wheels of the rail vehicle is arranged to attenuate an emanating from the rail vehicle magnetic field.

By the method according to the invention, the advantages of the sensor are achieved. In addition, by attaching the sensor coil at approximately an orthogonal angle to a direction of movement of the metal or part metallic wheels of the rail vehicle, attenuation of a magnetic field emanating from a rail vehicle is achieved, largely independent of local conditions.

Advantageously, the coil core is designed and arranged such that the magnetic field generated by the sensor coil is radiated in the direction of the metallic or partially metallic wheels of the rail vehicle. hereby In particular, it is achieved that the sensor coil is set very sensitive in the direction of the expected metallic or partially metallic wheels of the rail vehicle.

It is also possible that the coil core along the longitudinal axis encloses a surface and at its ends has at least two end faces, from which the majority of the magnetic field enters and / or exits, wherein the coil core is positioned such that the two end faces in one Plane lie, which is spanned by a rail head to this opposite second rail head.

One advantage of this is that the spool core is not closed, whereby the largest part of the magnetic flux enters and exits through the at least two end faces on the spool core. Since the bobbin is disposed at an approximately orthogonal angle to the direction of movement of the metal or part metallic wheels of the rail vehicle, the magnetic field in the air above the sensor coil propagates, directed where the metallic or semi-metallic wheel of a rail vehicle to be detected is expected. This ensures that hit at any time, including during the passage of a wheel of a rail vehicle, the magnetic fields emitted by the rail vehicle at the same time on the two end faces of the sensor coil. As a result, a voltage is induced, which, however, due to different signs, cancel each other out. In addition, it is ensured by such a positioning that the coil core is arranged in the direction of the expected, emanating from the rail vehicle magnetic field.

Figur 1

eine schematische Darstellung des Spulenkerns der Sensorspule nach einer ersten Ausführungsform;

Figur 2

die Ausführungsform der Figur 1 mit einem eingezeichneten und schematisch abgebildeten zweiten Schienenkopf;

Figur 3

die erste Ausführungsform mit einem schematisch eingezeichneten Rad eines Schienenfahrzeuges;

Figur 4

eine zweite Ausführungsform des Sensors, wobei auf dem Spulenkern unterschiedliche Wicklungen aufgetragen sind;

Figur 5

eine dritte Ausführungsform des Sensors, wobei der Spulenkern unterschiedlich dimensionierte Schenkel aufweist;

Figur 6

eine vierte Ausführungsform des Sensors, wobei der Spulenkern Uförmig ist;

Figur 7

eine Kombination des zweiten, dritten und vierten Ausführungsbeispiels des Sensors.

Further details and advantages of the invention will now be explained in more detail with reference to some shown in the drawings and preferred embodiments. Show it:

FIG. 1

a schematic representation of the coil core of the sensor coil according to a first embodiment;

FIG. 2

the embodiment of the FIG. 1 with a drawn and schematically illustrated second rail head;

FIG. 3

the first embodiment with a schematically drawn wheel of a rail vehicle;

FIG. 4

a second embodiment of the sensor, wherein on the spool core different windings are applied;

FIG. 5

a third embodiment of the sensor, wherein the coil core has differently dimensioned legs;

FIG. 6

a fourth embodiment of the sensor, wherein the coil core is U-shaped;

FIG. 7

a combination of the second, third and fourth embodiment of the sensor.

In particular, it should be noted that the sensor coil of the present invention is constructed so that the emitted magnetic fields from the rail vehicle at the moment they reach the sensor coil, due to the coil structure and due to the position of the sensor coil, generate a voltage in the sensor coil that compensates. Thus, it is achieved by the structure and by the positioning of the sensor coil that compensate only the externally disturbing magnetic fields. The desired magnetic field, that is to say the magnetic field which is used to detect metal parts, in particular metallic or semi-metallic wheels of a rail vehicle, is not impaired by this structure and by this positioning.

The FIG. 1 schematically shows a first embodiment of the sensor for detecting metal parts, in particular metallic or semi-metallic wheels of a rail vehicle. Shown is a sensor coil 1, which has a coil core 2. With the dashed arrow 3, a direction of movement of a not shown wheel of a rail vehicle is indicated. The illustrated coil core 2 has a longitudinal axis 6, and two legs 8, 8 '. Each of these legs 8, 8 'has, on the end face 7, 7' spaced from the winding 9, a magnetic field induced by the winding 9, which is indicated schematically. From the FIG. 1 It can be seen that the spool core 2 is at an approximately orthogonal angle to the rail head 10. The electronics, which can drive the sensor coil 1 through the winding 9, is in the FIG. 1 and not shown in the following figures.

In the FIG. 2 is, analogous to FIG. 1 , a sensor coil 1 shown, which has a coil core 2. Likewise, the direction of movement 3 is not shown schematically by dashed arrows of wheels of the rail vehicle. From the FIG. 2 In particular, it can be seen that the end faces 7, 7 'of the spool core 2 are located in a plane which is spanned by the first rail head 10 and the second rail head 10' opposite thereto. The spool core 2 is located in an approximately orthogonal angle to the direction of movement 3 of the wheels of the rail vehicle.

The FIG. 3 shows a detailed view of the first embodiment, as already with respect to the FIGS. 1 and FIG. 2 described. Also shown is the wheel 4 of a rail vehicle, which moves in the direction of movement 3. Also shown is the magnetic field 5 of the rail vehicle, which is emitted by this. This magnetic field 5 can be generated for example by an eddy current brake, by magnetic rail brakes or by a strong current consumption of the drive units of the rail vehicle. It should be noted that the magnetic field 5 of the rail vehicle is present here only very schematically. Nevertheless, it can be seen that the magnetic field of the rail vehicle 5 enters the end faces 7, 7 'of the spool core 2 and is attenuated both by the symmetrical configuration of the spool core 2 and by the approximately orthogonal positioning of the spool core 2 compensates for the induced by this magnetic field 5 in the respective end surfaces 7, 7 'voltage. The connected to the winding 9 electronics (not shown) is thus affected by no interference voltage.

The FIG. 4 shows a second embodiment of the sensor coil. Here, too, the sensor coil 1 has a coil core 2, which is arranged at an approximately orthogonal angle to a direction of movement 3 of a wheel of a rail vehicle 4. In the present embodiment, magnetic fields 5 are emitted, for example, by the electric drive (not shown) of the wheel of the rail vehicle 4, which respectively enter the end faces 7, 7 '. It can also be seen that more magnetic field lines enter into the end face 7 than in the end face 7 '. In order nevertheless to allow a weakening of the emitted magnetic field 5, or the voltage induced thereby, a winding 9 is wound around the leg 8, which has fewer turns than the winding 9 'around the leg 8'. This will achieved that the emitted magnetic field 5 is attenuated, or the voltage generated by this field in the two legs 8, 8 'is equal in magnitude, whereby no interference voltage to an electronics connected to the sensor coil occurs. This is achieved both by the orthogonal arrangement to the direction of movement 3 of the wheel of the rail vehicle 4, as well as by the shape of the spool core 2 and by the different windings 9, 9 '.

The FIG. 5 shows a third embodiment of the sensor coil 1 according to the invention, wherein the sensor coil 1 also has a coil core 2 here. The difference to the first or second embodiment is that the leg 8 'or the end face 7' is dimensioned larger than the leg 8 and the end face 7. By this different dimensioning of the legs 8, 8 'occurs in each of Leg 8, 8 'in total one with respect to the magnetic flux equal to a large magnetic field 5, and, due to the larger dimension of the leg 8', a magnitude of equal magnitude voltage is induced. This makes it possible that the same winding numbers 9 are used both for the leg 8 and for the leg 8 '. An electronics connected to the sensor coil 1 is consequently disturbed by no interference voltage.

The FIG. 6 shows a fourth embodiment of the sensor coil 1, wherein the coil core 2 has a U-shape. Of course it is also possible, although in the FIG. 6 not shown, that the sensor core 2, for example, an E-shape, or an F-shape. Regardless of the specific forms mentioned each coil core is possible, which has at least two legs due to its shape. At the in FIG. 6 embodiment shown, both the wheel of the rail vehicle 4, as well as with a dashed arrow, the direction of movement 3 of this wheel of the rail vehicle 4 is indicated. By the drive (not shown) of the wheel of the rail vehicle, a magnetic field 5 is generated. This magnetic field 5 strikes with different intensity on the end faces 7, 7 'and thus induces a voltage in the legs 8, 8'. Due to the orthogonal arrangement of the coil core, as well as due to the U-shaped form of the coil core, the resulting in the winding 9 voltages, which are induced by the magnetic field 5 of the rail vehicle, the same size, but with a different sign afflicted. As a result, these induced Tensions on each other. An electronics connected to the coil core 2 (not shown) thus experiences no interference voltage.

The FIG. 7 shows a combination of some of the preceding embodiments. With such a combination, for example, the direction of movement 3 of a vehicle can be detected very reliably. Likewise, this makes it possible that a wheel count is performed. In this way, for example, statements about a movement of various sections of a railway operating area can be made remotely. Each of the illustrated sensor coils 1 each have a coil core 2. For a better overview, the magnetic field generated by the wheel of the rail vehicle 4, for example by the drive of the wheel of the rail vehicle 4, is not shown in FIG FIG. 7 , Each of the coil cores 2 in each case has legs 8, 8 ', wherein these each comprise an end face 7, 7'. Windings 9 and 9 'are wound around these legs 8, 8'. It should be noted that the coil cores 2 are arranged in their longitudinal axis 6 of the respective bobbin 2 at an approximately orthogonal angle to the rail head 10. By such an arrangement and by such a construction of the coil cores, the magnetic fields actively emitted by the rail vehicle or the voltages induced by these magnetic fields in the respective end faces 7, 7 'are compensated, so that an electronics connected to the respective coil cores 2 (not shown) experiences no interference voltage.

LIST OF REFERENCE NUMBERS

1

sensor coil

2

Plunger

3

movement direction

4

Wheel of the rail vehicle

5

magnetic field of the rail vehicle

6

Longitudinal axis of the spool core

7, 7 '

faces

8, 8 '

leg

9, 9 '

windings

10, 10 '

railhead

Claims (16)

Sensor for detecting metal parts, in particular metallic or semi-metallic wheels of a rail vehicle,
with an electrical resonant circuit which has at least one sensor capacitance and a sensor coil (1) which comprises a coil core (2) and generates a magnetic field,
characterized in that
the coil core (2) of the sensor coil (1), with respect to its longitudinal axis (6), is arranged approximately at an orthogonal angle to a direction of movement (3) of the metallic or semi-metallic wheels (4) of the rail vehicle, around a magnetic signal emanating from the rail vehicle Attenuate field (5). Sensor according to claim 1,
characterized in that
the spool core (2) consists of highly permeable material. Sensor according to claim 1 or 2,
characterized in that
the coil core (2) is a ferrite core. Sensor according to one of the preceding claims,
characterized in that
the coil core (2) along the longitudinal axis (6) encloses a surface and at its ends at least two end faces (7, 7 '), from which the majority of the magnetic field enters and / or exits. Sensor according to one of the preceding claims,
characterized in that
the spool core (2) has a U-shape, an E-shape, or an F-shape. Sensor according to claim 5,
characterized in that
the spool core (2) due to its shape, at least two legs (8, 8 '). Sensor according to claim 6,
characterized in that
the windings (9) of the sensor coil (2) are wound asymmetrically about the legs (8, 8 '). Sensor according to one of the preceding claims,
characterized in that
the sensor coil (1) has different winding numbers at different points of the coil core (2). Sensor according to one of the preceding claims,
characterized in that
a winding (9) is applied along the spool core (2). Sensor according to one of the preceding claims,
characterized in that
at least one winding (9) of the sensor coil (1) at any location of the spool core (2) is arranged. Sensor according to one of claims 6 to 10,
characterized in that
the legs (8, 8 ') are dimensioned differently. Sensor according to one of the preceding claims,
characterized in that
the sensor is installed in a housing, wherein the magnetic field of the sensor coil (1) is dimensioned such that it goes out of the housing. Use of at least two sensors according to one of the preceding claims for determining a direction of movement (3) of a rail vehicle. Method for attenuating a magnetic field (5) emanating from a rail vehicle, comprising the step of attaching a sensor coil (1) of an electrical oscillating circuit, the sensor coil (1) having a coil core (2) which, relative to its longitudinal axis (6) , is arranged approximately at an orthogonal angle to a direction of movement (3) of the metallic or semi-metallic wheels (4) of the rail vehicle in order to attenuate a magnetic field (5) emanating from the rail vehicle. Method according to claim 14,
characterized in that
the coil core (2) is designed and arranged in such a way that the magnetic field generated by the sensor coil (1) is radiated in the direction of the metallic or partially metallic wheels (4) of the rail vehicle. Method according to one of claims 14 or 15,
characterized in that
the coil core (2) along the longitudinal axis (6) enclosing a surface and at its ends at least two end faces (7, 7 '), from which the majority of the magnetic field enters and / or exits, the coil core (2) in such a way is positioned so that the two surfaces (7, 7 ') lie in a plane which is spanned by a rail head (10) to a second rail head (10') opposite thereto.

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