JP6818329B2 - Wheel detector - Google Patents

Description

The present invention relates to a device for detecting a train wheel (axle).

Conventionally, a wheel (axle) detector that detects a wheel (axle) passing on a rail has been known in order to count the number of axles of a train. In a conventional wheel detector, a pair of coils (transmit coil and receive coil) are arranged on both sides of the rail, and both coils form an AC magnetic circuit. When the wheels are located between the two coils, the wheels As a result of the change in the magnetic circuit, the presence of the wheel is detected by utilizing the change in the magnetic field input to the receiving coil.

In a wheel detector having such a configuration, generally, the induction voltage V1 induced in the receiving coil when the wheel is not detected (when there is no wheel) and the induction voltage V1 induced in the receiving coil when the wheel is detected (when there is a wheel). It is desirable that the ratio to the voltage V2 (V1 / V2) is as large as possible.

It should be noted that, in Japanese Patent Application Laid-Open No. 7-15807, a transmission coil and a reception coil are provided on both sides of the rail, and a current is passed through the transmission coil to generate a magnetic flux, which is received by the reception coil. A wheel detector that detects a wheel by utilizing the fact that the reception level drops when entering between both coils is disclosed.

Jikken No. 7-15807 (Fig. 4a)

An object of the present invention is the ratio (V1) of the induced voltage V1 induced in the receiving coil when the wheel is not detected (without the wheel) and the induced voltage V2 induced in the receiving coil when the wheel is detected (when the wheel is present). / V2) is to provide a wheel detector capable of increasing.

The wheel detector according to the present invention is a wheel detector including a transmitting coil and a receiving coil arranged so as to sandwich a rail, and the receiving coil is a planar coil (single planar coil or laminated coil). It is composed of a flat coil), and the flat coil is characterized in that it is arranged along a magnetic flux formed by the transmission coil. That is, the electromotive force due to the magnetic flux that vertically penetrates the plane coil surface of the receiving coil can be approximately ignored, and the plane coil surface is arranged at a position that approximately falls within the gentle magnetic flux diffusion surface. To do.

In this case, the planar coil may be configured by a planar coil. Further, in this case, the planar coil may include a plurality of the planar coils, and the plurality of planar coils may be stacked in the vertical direction. Further, in this case, the connecting line connecting the first planar coil and the second planar coil adjacent to the first planar coil may not cross the coil surface of the planar coil. Further, in this case, both the end end of the first flat coil and the start end of the second flat coil adjacent to the first flat coil may be arranged near the center of the coil.

Further, in the above case, the flat coil may be wound in a rectangular shape and may be arranged so that the long side is parallel to the rail.

Further, in the above case, the planar coil may further include an electrostatic shield member. In this case, the electrostatic shield member may be composed of a blind wire grounded on one side.

Further, in the above case, the transmission coil may be formed of a tubular coil.

Further, in the above case, a metal plate for adjusting the magnetic flux of the transmission coil may be further provided behind the transmission coil. In this case, the metal plate may be configured so that the angle of the transmission coil with respect to the main shaft can be adjusted.

Further, in the above case, a tubular magnetic member may be further provided in front of the transmission coil.

Further, in the above case, a magnetic member may be further provided below the receiving coil. Further, in this case, a second magnetic member may be further provided on the rail side below the receiving coil.

Further, in the above cases, a compensation coil for compensating for the influence of the orbital current may be further provided. In this case, the compensation coil may be formed of a planar coil and may be arranged in the vicinity of the receiving coil. Further, in this case, a filter may be further provided to remove the signal of the drive frequency of the transmission coil from the output of the compensation coil.

According to the present invention, the induced voltage V2 induced in the receiving coil at the time of wheel detection (with wheels) can be minimized to about the noise level. Therefore, conventionally, when wheels are not detected (without wheels). It is possible to increase the ratio (V1 / V2) of the induced voltage V1 induced in the receiving coil to the induced voltage V2 induced in the receiving coil when the wheel is detected (when there is a wheel).

It is a figure (the 1) which shows the state of the magnetic flux divergence from a transmission coil L1. It is a figure (the 2) which shows the state of the magnetic flux divergence from a transmission coil L1. It is a figure which shows the state of the change of the voltage detected by the receiving coil L2 when a wheel passes. It is a figure for demonstrating the outline of embodiment of this invention. It is a figure (the 1) for demonstrating the effect of this invention. It is a figure (the 2) for demonstrating the effect of this invention. It is a figure which shows the structural example of the planar coil used in this invention. It is a figure which shows the structural example of the planar coil which constitutes the planar coil. It is a figure for demonstrating the structure of the 1st wheel detector (1st Embodiment) by this invention. It is a figure for demonstrating the structure of the 2nd wheel detector (second embodiment) by this invention. It is a figure for demonstrating the structure of the 3rd wheel detector (third embodiment) by this invention. It is a figure for demonstrating the structure of the 4th wheel detector (fourth embodiment) by this invention. It is a figure (the 1) for demonstrating the structure of the fifth wheel detector (fifth embodiment) by this invention. It is a figure (the 2) for demonstrating the structure of the 5th wheel detector (fifth embodiment) by this invention. It is a figure which shows the configuration example of the signal processing system which processes the output signal of the receiving coil L2 and the compensation coil L3.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the outline of the principle of the present invention will be described.

The present invention is a wheel detector that uses magnetic flux coupling between a pair of coils (transmit coil L1 and receive coil L2) arranged across a rail, and when the wheels pass between both coils, the wheels have a magnetic flux. When the position is a predetermined distance before the maximum shielding position (or a predetermined distance after the maximum shielding position) (hereinafter referred to as "without wheels"), the high-frequency magnetic flux generated by the transmitting coil L1 causes the receiving coil L2 to receive the voltage. The induced voltage V1 is maximized, and the induced voltage V2 induced in the receiving coil L2 is minimized when the wheel is in a position where the magnetic flux is maximally shielded (hereinafter, referred to as “when the wheel is present”). It makes it possible to achieve things at the same time.

Since the noise voltage V3 caused by the magnetic flux noise and the circuit noise is usually superimposed on the voltages V1 and V2 observed in the receiving coil L2, the S / N as an evaluation index for determining the presence or absence of wheels is as follows. It is represented by Equation 1.

S / N = (V1 + V3) / (V2 + V3) ... (1)

Normally, V3 is negligibly smaller than V1, so in order to maximize S / N, the maximization of V1 and the minimization of V2 + V3 may be satisfied at the same time. Further, when the distance between the L1 and L2 coils and the spindle angle of the coils are fixed, V1 is mainly determined by the exciting current of the transmitting coil L1, so maximizing the S / N makes V2 + V3 a noise level regardless of the exciting current. It will be attributed to minimization.

Conventionally, it is composed of a solenoid having a concentric shaft length of a cylindrical type or a square cylinder type in which each of the transmitting coil L1 and the receiving coil L2 is wound in multiple layers, and under a constant L1 exciting current, the transmitting coil L1 and the receiving coil L2 By adjusting the relative position of the coil and the relative angle between the coil spindles, V1 was maximized and V2 was minimized. However, the magnetic flux vector field diverging from the transmitting coil L1 symmetrically with respect to the coil spindle has a non-uniform distribution in both the spindle direction and the cross-sectional direction of the receiving coil L2 even at the position of the receiving coil L2, and is shielded even when there are wheels. As a result of the remaining leakage magnetic flux that surrounds the rail and the wheel without being affected by the above, a voltage component of V2 >> V3 remains in V2 in proportion to the L1 drive current, and the S / N is, for example, , About 15 dB was the limit.

In the present invention, the receiving coil L2 is composed of a planar coil (consisting of a single planar coil or a laminated planar coil), and a sensitivity region capable of planar approximation along the diffusion magnetic flux vector flow from the transmitting coil L1. The receiving coil L2 is arranged in S. Further, by providing an adjusting member (specifically, a metal plate) for adjusting the L1 magnetic flux vector penetrating the surface of the receiving coil L2 on the back side of the transmitting coil L1, V2 can be adjusted to be almost 0. It is something to do.

By adopting the above configuration, S / N = V1 / V3, and V1 is proportional to the L1 drive current. Therefore, for example, a high S / N of about 30 to 60 dB can be obtained.

Here, the sensitivity region S that can be approximated in a plane is the thickness of the flat coil in a range in which the magnetic flux formed by the transmission coil L1 does not form a recirculation magnetic field together with the axial length distance of the coil (a range in which magnetic flux inversion does not occur). In a scale range of about, it means a range in which the amount of gradual vector change of magnetic flux can be regarded as linear, and in the sensitivity region S, the maximum width of the planar coil is defined as the wheel movement direction (X-axis direction in FIG. 1). The magnetic flux can be regarded as almost uniform over the same range, and the voltage change due to the wheel movement becomes gradual, which is an advantage in the signal detection band. On the other hand, in the direction orthogonal to the wheel moving direction, the magnetic flux penetrates the coil surface, so that the magnetic flux vector angle range that can be approximated by a plane becomes narrow, and the magnetic flux adjustment by the adjusting member (metal plate) becomes effective.

Next, the details of the principle of the present invention will be described.

1 and 2 are views showing the state of magnetic flux divergence from the transmission coil L1. FIG. 1 shows the state of magnetic flux divergence on the YZ plane (cross section viewed from the axle movement direction), and FIG. 2 shows the state of magnetic flux divergence on the XY plane (rail upper surface).

Here, the direction along the rail 10 (wheel moving direction 11) is the X-axis direction, orthogonal to this, the direction connecting the transmitting coil L1 and the receiving coil L2 is the Y-axis direction, and the direction perpendicular to the ground is the Z-axis direction. There is. Then, for example, in the case of the X-axis direction, it is basically assumed that both positive and negative directions are included. Further, for the sake of simplicity, the rail 10 is omitted in FIG.

The magnetic flux generated by applying an exciting current to the transmission coil L1 wound up in a tubular shape diverges symmetrically with respect to the coil spindle, and forms a magnetic flux loop that goes around through the outer space of the coil. The inductance of the transmission coil L1 is, for example, about several mH, and resonance is usually used to generate a highly efficient magnetic flux.

For both the transmitting coil L1 and the receiving coil L2, an air-core coil is usually used due to restrictions such as temperature and stability in an actual installation environment. Further, in order to avoid interference with various train operation system signals and commercial power frequency, an alternating current of about 30 kHz is usually used as the L1 exciting current.

As shown in FIG. 2, the magnetic flux of the transmission coil L1 is partially cut off by the rail 10 but diverges as a whole to form a magnetic flux loop. The magnetic flux radiated from the transmission coil L1 which is an air-core coil forms a steep return magnetic flux along the side surface of the coil near the coil as the vector sum of the leakage magnetic flux of each winding ring. In the direction of the main axis, the magnetic flux density decreases with the distance from the coil end, and in the direction deviating from the main axis, the position where a part of the magnetic flux rotates and turns back as a recirculation vector shifts in the direction orthogonal to the main axis.

For V1, it is advantageous in terms of S / N that the distance between the transmitting coil L1 and the receiving coil L2 is small, but at that time, the lower limit of the distance between the transmitting coil L1 and the receiving coil L2 is the folding back of the L1 reflux magnetic flux vector. The position is determined within the range where the position does not reach the receiving coil L2 position. This is, for example, about 100 to 200 mm, which is the same dimensional distance as the spread of the transmission coil L1 determined from the actual rail size.

When the wheels (and rails) block part of the magnetic flux loop of the transmit coil L1, the magnetic flux of the transmit coil L1 creates an eddy current in the high frequency skin effect depth range of the metal surface. As a result of most of the electrical resistance of iron materials such as rails and wheels being consumed as Joule heat, the generation of reverse magnetic flux from these iron material eddy currents is at a negligible level, and the magnetic flux of the transmission coil L1 is determined by the wheels and rails. It will be simply shielded. As the wheel passes, the magnetic flux shielding region moves in the sensitivity region S where the receiving coil L2 is placed, and as a result, the amount of magnetic flux penetrating the fixed receiving coil L2 changes with time, and an induced voltage is induced.

In the examples shown in FIGS. 1 and 2, for convenience, the main shaft of the transmission coil L1 is arranged so as to be horizontal (Y-axis direction) toward the rail direction, but regarding the angular arrangement on the YZ plane. There is an appropriate angle that maximizes the magnetic flux shielding when there are wheels. In the actual wheel detection, the angle at which V1 is maximized is adopted.

When the main axis of the transmission coil L1 is oriented in the Y-axis direction, a divergent magnetic flux vector as shown in FIG. 1 is generated. For example, when the size of the transmitting coil L1 is 50 × 50 × 50 mm ³ (about 10 mH), the divergence angle θ from the end of the transmitting coil L1 to the region that can be approximated in a plane over the receiving coil L2 region (about 100 mm) in the XY plane is , About 60 degrees.

The density of the magnetic flux diverging in the main axis direction of the transmitting coil L1 rapidly decreases with the distance between the transmitting coil L1 and the receiving coil L2, and the sensitivity that the magnetic flux shielding effect on the receiving coil L2 is effective when passing through the wheels. As the region S, a range determined by the magnetic flux divergence angle is used in the Y-axis direction and close to the wheel in the X-axis direction.

Conventionally, in order to obtain a high S / N without impairing the transient response transmission characteristics of the detection voltage pulse when passing through the wheel, a multi-layer winding is applied as the receiving coil with almost the same shape and cross-sectional area as the transmitting coil. A tubular broadband solenoid having a coil shaft length of about 10 mH has been used.

Since the sensitivity region S where the magnetic flux shielding effect can be expected with respect to the receiving coil L2 is restricted by the flange position of the wheel in the Z-axis direction, the upper limit comes to a hanging portion of about several cm from the upper surface of the rail. When a tubular coil is used as the receiving coil L2, since the tubular coil has a shaft length, the leakage magnetic flux wraparound condition differs between the lower end and the upper end of the coil, and the magnetic flux shielding effect by the wheels is also obtained by the receiving coil L2. There is a problem that it decreases on the lower surface as compared with the upper surface, and the effective winding ratio that contributes to S / N decreases.

Of the positions a, b, and c on the rail 10 shown in FIG. 2, the point b corresponds to the position where the YZ surface including the main shaft of the transmission coil L1 intersects the rail 10 when there are wheels. When there are wheels, the magnetic flux vector of the transmitting coil L1 penetrating the receiving coil L2 placed in the sensitivity region S is in the X-axis direction (rail direction) on the receiving coil L2 surface with the YZ plane at this point b as a boundary. Since the distribution is symmetrical, the minimum voltage V2 is shown at point b, and the maximum voltage V1 is shown at point a before passing and point c after passing.

FIG. 3 is a diagram showing a state of change in voltage detected by the receiving coil L2 when the wheel passes through.

As shown in the figure, the voltage detected by the receiving coil L2 shows a minimum value when the wheel is located at point b.

The detected voltage at each position due to the wheel movement shown in the figure is finally detected as a pulse voltage signal determined by the train speed. Normally, the ac interval is about several cm, so if the train speed is 100 km / h, this pulse waveform becomes a transient response signal of about 1 msec, and in order to process this as a wideband signal such as amplification, it is 20 dB or more in this band. S / N is required.

In the present invention, first, the receiving coil L2 is a flat coil (consisting of a single flat coil or a laminated flat coil). For example, the distance between the transmitting coil L1 and the receiving coil L2 is about 20 cm so that the coil pair in the wheel detection is close to the rail and the wheel (when passing), and the receiving coil L2 is horizontal in the sensitivity region S. It is placed at a position several cm away from the wheel (when passing) in both vertical directions.

Next, the outline of the embodiment of the present invention will be described.

FIG. 4 is a diagram for explaining an outline of an embodiment of the present invention. In the figure, the divergent magnetic flux on the YZ plane is shown. Further, in the figure, for comparison, the conventional cylindrical coil 41 is shown together with the planar coil of the present invention.

The flat coil is composed of a flat coil wound in a rectangular shape, the long side of the flat coil wound in a rectangular shape is parallel to the rail, and is symmetrical with respect to the main axis of the transmission coil L1 in the XY plane. (The YZ plane including the main shaft of the transmission coil L1 passes through the center of the long side). Since the planar coil has little change in the in-plane magnetic flux with respect to the deviation from point b (equilibrium position when the wheel is present) in the wheel traveling direction (X-axis direction) in the sensitivity region S, it has almost no sensitivity. The adjustment of the receiving coil L2 for minimizing V2 is concentrated in the adjustment of the vertical positional deviation h from the coil spindle and the angle φ.

On the other hand, when the receiving coil L2 is a cylindrical coil, the magnetic flux divergence surface of the transmitting coil L1 is curved and distributed along the receiving coil L2 axis in any relative arrangement because of the coil spindle length. Therefore, unlike the flat coil, it cannot be adjusted at an angle and position, there is residual magnetic flux through it, and there is a limit to minimizing V2.

Since all the windings of the flat coil constituting the flat coil are in a single plane, the flat coil surface approximately matches the magnetic flux surface of the transmission coil L1 with an angular accuracy determined by the diameter of the winding material and the spread of the coil shape. Or you can follow along.

In order to maximize V1, the transmitting coil L1 is usually arranged near the upper surface of the rail, but the receiving coil L2 is restricted in the vertical direction so as not to come into contact with the flange of the wheel, and the main shaft of the transmitting coil L1 is restricted. It is arranged at a position displaced by a predetermined distance h in the vertical direction from the above. As a result, when there are wheels, the receiving coil L2 surface gives a V2 minimum value at the rotation angle φ corresponding to the deviation h in the YZ surface in order to match or follow the diffusion magnetic flux flow. The magnetic flux shielded under this condition recovers when there is no wheel, and V1 is output as the magnetic flux penetrating the receiving coil L2 surface.

In this way, the S / N can be maximized by adjusting the position and angle of the receiving coil L2 plane, but in order to realize a high S / N of approximately 20 dB or more, the magnetic flux diverging surface of the receiving coil L2 surface and the transmitting coil L1 It is necessary to remove the imperfections remaining in parallelism (due to the curvature of the L1 magnetic flux divergence vector) and bring the lower limit of V2 as close to zero as possible. However, since the magnetic flux diffusion of the transmission coil L1 is three-dimensional, it is not possible to completely eliminate the magnetic flux component penetrating the L2 surface only by adjusting the angle of the planar coil L2. The change in the magnetic flux vector curvature in the plane coil plane is easy to fine-tune because the current induced in the plane coil by the through magnetic flux is averaged as a path integral over the L2 winding.

In the present embodiment, as a means for finely adjusting the divergent magnetic flux vector near the surface of the receiving coil L2, a metal having low electrical resistance (for example, copper (Cu) or aluminum) is placed on the back side (opposite side of the receiving coil L2) of the transmitting coil L1. The adjusting plate M made of (Al)) is arranged, and the generated eddy current magnetic flux vector is used. The eddy current magnetic flux is diffused and radiated along the normal line perpendicular to the plane of the adjusting plate M, and the intensity distribution on the radiating plane is similar to the incident magnetic flux distribution, so that the reception is located at a position away from the transmission coil L1. The deviation of the L1 divergent magnetic flux in the coil L2 from the flatness can be corrected, and V2 can be set to approximately 0. At this time, S / N = V1 / V3, and S / N proportional to the drive current of the transmission coil L1 can be obtained.

5 and 6 are diagrams for explaining the effect of the present invention. FIG. 5 shows the relationship between the L1 drive current and the L2 detection voltage. The horizontal axis of the figure shows the L1 drive current (unit: A), and the vertical axis of the figure shows the L2 detection voltage (L2 detection voltage). Unit: mV) is shown. Further, FIG. 6 shows the relationship between the L1 drive current and the S / N, the horizontal axis of the figure shows the L1 drive current (unit: A), and the vertical axis of the figure shows the S / N. Indicates N.

In the conventional cylindrical coil pair, since the L1 magnetic flux proportional component remains in V2, as shown in the graphs 511 and 512 of FIG. 5, both V1 and V2 increase proportionally with the increase in the L1 drive current. , As shown in the graph 610 of FIG. 6, S / N = V1 / V2 remains a constant value.

On the other hand, in the present embodiment, by using the flat coil and the correction metal plate, V2 can be lowered to the residual noise level regardless of the L1 drive current, as shown in the graph 522 of FIG. As shown in the graph 521 of the figure, V1 is proportional to the L1 drive current, so that S / N = V1 / V3 can be arbitrarily set as shown in the graph 620 of FIG. ..

The signal when passing through the wheels is a time pulse waveform obtained by dividing the dimension in the direction (X-axis direction) along the rail of the receiving coil L2 by the train speed. However, the planar coil of the present invention has a time pulse waveform as compared with the tubular coil. Since the sensitivity range can be set longer in the rail direction, the pulse width can be increased several times. As a result, the transient response signal frequency is lowered and the band constraint of the signal processing system is reduced, so that there is a practical merit in terms of improving the reliability of the calculation system from the signal to the wheel detection and the cost. The distance f1 between the adjusting plate M and the end face of the transmission coil L1 is, for example, about 0 to 10 mm, and the tilt angle of the adjusting plate M is adjusted to be V2 = 0, for example, in the range of 0 to 45 degrees. It will be possible.

Next, the details of the planar coil used in the present invention will be described.

FIG. 7 is a diagram showing a configuration example of a planar coil used in the present invention. The figure (a) shows a plan view, and the figure (b) shows a front view.

As shown in the figure, the planar coil 700 includes two planar coils 711 and 712, and the two planar coils 711 and 712 are stacked in the vertical direction.

In the present embodiment, each of the planar coils 711 and 712 uses a litz wire obtained by twisting 20 to 30 copper strands having a diameter of about 50 μm in order to reduce the loss due to a high frequency current in the 30 kHz band, and has a rectangular shape. It is formed by winding in a plane, and is mounted as a flat coil sheet with a thickness of 0.5 mm or less. The maximum value of the shape dimension of the rectangular flat coil is determined by the divergence angle of the magnetic flux of the transmission coil L1 and the distance from the transmission coil L1, and the long side along the wheel moving direction is, for example, about 10 cm.

When such a single-layer flat coil is used, it is possible to obtain a transient signal that is easy to process, for example, with a pulse width of about 1 ms at a train speed of about 100 km / h.

As the distance between the transmitting coil L1 and the receiving coil L2 increases, the divergent magnetic flux density decreases, and the magnetic flux shielding effect of the wheels also decreases. Therefore, the effective length of the short side of the flat coil is, for example, about 3 to 8 cm. Since the flat coil detects signals in a non-resonant manner, in order to increase the magnetic flux detection sensitivity, the winding must have the maximum winding length within the range where the self-resonant frequency of the coil does not fall below the L1 drive frequency, and the winding length is long or short. The litz wire diameter will be determined so that it fits in the area surrounded by both sides. Normally, the maximum inductance per flat coil is about 1 to 2 mH, so the detection sensitivity can be increased by stacking a plurality of flat coils.

Although an example of a two-layer coil is shown in FIG. 7, for example, about 10 layers can be laminated to form a multi-layer coil having a coil thickness of 5 mm or less and a self-inductance of about 10 to 20 mH. Regarding the angular resolution accuracy of the magnetic flux change, for example, the accuracy obtained with a flat coil having a short side of 5 cm is about ± 0.5 degrees, and the receiving coil L2 in the diffused magnetic flux plane of the transmitting coil L1 is used to minimize V2. Highly accurate adjustment is possible by adjusting the placement position of. Regarding the thickness of the laminated flat coil, for example, 1 to 10% of the coil side length is in the practical range.

Although the impedance of the laminated coil is high, the noise voltage V3 can be lowered by using the electrostatic shield. In the example shown in FIG. 7, a pair of electrostatic shield members 721 and 722 are provided so as to sandwich the flat coils 711 and 712. Each electrostatic shield member 721, 722 is composed of, for example, a copper wire blind (sliding wire) having a wire diameter of about 0.3 mm, and by using one end of the copper wire blind as a shield ground, high-frequency magnetic flux is transmitted. It is possible to perform electrostatic shielding without affecting the voltage.

FIG. 8 is a diagram showing a configuration example of each planar coil constituting the planar coil shown in FIG. 7. FIG. 8A shows a plan view of the flat coil arranged on the upper side, and FIG. 8B shows a plan view of the flat coil arranged on the lower side.

As shown in the figure, the upper flat coil 810 is wound counterclockwise from the winding start end 811 arranged near the outer edge of the coil toward the winding end end 812 arranged near the center of the coil. ..

On the other hand, the lower flat coil 820 is wound counterclockwise from the winding start end 821 arranged near the center of the coil toward the winding end end 822 arranged near the outer edge of the coil.

By winding a pair of flat coils adjacent to each other in the vertical direction as shown in the figure, the winding end point 812 of the upper flat coil 810 and the winding start end 821 of the lower flat coil 820 are both. Since the coil is arranged near the center of the coil, the connection between the upper flat coil 810 (winding end end 812) and the lower flat coil 820 (winding start end 821) can be easily performed. For example, even when a two-layer flat coil is mounted by a wiring pattern formed on both sides of a printed wiring board, by forming a winding pattern as shown in the figure, the printed wiring can be made with one through connection hole. Wiring between the flat coils formed on both sides of the substrate can be realized. In addition, when a flat coil is mounted with a wire rod, the connecting wire connecting the adjacent flat coils does not cross the coil surface, so that the laminated surface does not have irregularities and the flatness of the flat coil can be ensured. Become.

Further, since the winding start end 811 of the upper flat coil 810 and the winding end end 822 of the lower flat coil 820 are both arranged near the outer edge of the coil, they can be easily connected to the outside. Will be.

<< First Embodiment >>
FIG. 9 is a diagram for explaining the configuration of the first wheel detector (first embodiment) according to the present invention.

As shown in the figure, the first wheel detector 900 according to the present invention includes a transmission coil L1, a reception coil L2, and an adjustment plate M. The transmitting coil L1 and the receiving coil L2 are arranged on both sides of the rail 10 so as to sandwich the rail 10.

The transmission coil L1 is composed of a tubular coil and is arranged so as to form a predetermined angle with respect to a horizontal plane (ground). On the other hand, the receiving coil L2 is composed of a planar coil and is arranged along the magnetic flux formed by the transmitting coil L1. That is, the electromotive force due to the L1 magnetic flux that vertically penetrates the flat coil surface of the receiving coil L2 can be approximately ignored, and the plane coil surface is arranged at a position that approximately falls within the gentle magnetic flux diffusion surface.

The adjusting plate M is composed of a metal plate and is arranged behind the transmission coil L1. The metal plate constituting the adjusting plate M is made of a highly conductive material such as copper or aluminum. For example, in the case of the minimum size, the metal plate is formed to have the same size as the coil cross section of the transmission coil L1 and has a maximum size. In the case of the size, it is formed to have the same size as the receiving coil L2. Further, the adjusting plate M is configured so that the angle of the plate surface with respect to the main shaft 901 of the transmission coil L1 can be adjusted by an angle adjusting mechanism (not shown).

The position of the receiving coil L2 in the Z-axis direction is, for example, 5 cm or more vertically downward from the upper surface of the rail 10 in order to avoid contact with the flange 21 of the wheel 20. The upper limit of the distance g between the transmitting coil L1 and the receiving coil L2 is, for example, about 40 cm as the range in which the divergence of the L1 magnetic flux is small, and the lower limit is the position where the receiving coil L2 has a high magnetic flux shielding effect by the wheels 20. As a range in which the magnetic flux plane can be approximated in a plane, for example, it is optimized within a range of about 25 cm.

The magnetic flux in the vicinity of the receiving coil L2 forms a magnetic flux surface that gently diverges so as to be axisymmetric with respect to the main shaft 901 of the transmitting coil L1.

The adjustment of the wheel detector 900 shown in the figure is performed, for example, as follows.

First, the electromotive force due to the magnetic flux component that vertically penetrates the L2 surface of the receiving coil is adjusted to zero when there are wheels. At this time, the magnetic flux that penetrates the receiving coil surface in the Z-axis direction is the L1 magnetic flux that is not shielded by the wheels. , The "deviation" from the flatness due to the magnetic flux diverging surface having a curvature remains. In order to eliminate this residual magnetic flux, the distance g between the coils for which the adjusting plate M is effective is, for example, in the range of 20 to 30 cm when the transmission coil L1 is a 50 mm square rectangular coil.

To adjust V2 to the minimum (zero) under the condition of having wheels, first, for example, when the position of the adjustment plate M is a distance f1 = 0 to 5 mm from the transmission coil L1, the L1 axis cross angle β = 0 and the reception coil L2 Is placed at a position closest to the wheel flange 21 within the allowable setting range, and the fanning angle δ is adjusted in the YZ plane so that V2 becomes the minimum. At this stage, the minimum value V2 = 0 is not always obtained.

Next, the fan angle α of the spindle 901 of the transmission coil L1 and the coil spacing g are adjusted in the YZ plane so that V1 is maximized under the condition without wheels. At this time, since the receiving coil L2 is located at a position deviated from the axis 901 by a vertical distance h, the divergence vector plane of the L1 magnetic flux is an inclined plane substantially equal to δ. This inclination is mainly determined by the distance between the coils g and the coil angle α of the transmission coil L1. For example, when g is 250 mm and α is 20 to 30 degrees, δ is about 20 to 30 degrees.

Next, when the fanning angle δ of the receiving coil L2 is finely adjusted so that V2 becomes the minimum again under the condition of having wheels, the position where V2 becomes the minimum is determined as the equilibrium position of the transmission / reception coil pair. As a final adjustment, V2 can be set to almost 0 by adjusting the tilt angle β of the adjustment plate M. By adjusting the β angle, the magnetic flux diffusion surface at the position of the receiving coil L2 is changed by a minute angle in the YZ surface, so that the component proportional to the L1 magnetic flux of V2 can be canceled.

Once the distance g between the coils is determined, a series of adjustments only need to be performed at the installation site for β, and g, α, and δ are determined in advance at another location (for example, in the factory before shipment). be able to. This greatly simplifies the on-site adjustment work of the wheel detector in S / N maximization including V2 = 0.

<< Second Embodiment >>
Next, another embodiment of the wheel detector will be described. In the following, basically, only the parts different from the above-described first embodiment will be described. The same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 10 is a diagram for explaining the configuration of the second wheel detector (second embodiment) according to the present invention.

As shown in the figure, the second wheel detector 1000 according to the present invention includes a transmitting coil L1, a receiving coil L2, an adjusting plate M, a tubular magnetic member D1, and a magnetic plate D2. The second wheel detector 1000 is obtained by adding a tubular magnetic member D1 and a magnetic plate D2 to the first wheel detector 900 described above.

The tubular magnetic member D1 is a magnetic material having a tubular shape, and is arranged in front of the transmission coil L1. The magnetic plate D2 is a magnetic material having a plate-like shape, and is arranged below the receiving coil L2.

The effect of the flat coil and the adjusting plate in the present invention is that V2 can be set to almost 0, but a tubular magnetic member D1 is further inserted as a magnetic pole member into the magnetic flux radiating portion on the L1 axis. By inducing the L1 magnetic flux divergence in the receiving coil L2 position direction, for example, V1 can be improved by 20 to 30%, and performance exceeding S / N = 60 dB can be realized.

When the planar coil surface is on the gentle divergence surface of the L1 magnetic flux, the detected voltage is obtained as a result of the path integral over the planar coil surface, so the final fine adjustment with wheels can be made part of the receiving coil surface. It can be realized by giving a minute magnetic flux vector change to.

Further, by inserting the magnetic plate D2 below the receiving coil L2, the magnetic flux diverging surface in the vicinity of the receiving coil L2 can be locally lowered in the vertical direction, and the adjustment by the adjusting plate M can be further facilitated. The magnetic plate D2 has an area of about 10 to 50% of the flat coil constituting the receiving coil L2, and a sufficient effect can be obtained.

The tubular magnetic member D1 and the magnetic plate D2 need to be adapted to the operating environment at the time of wheel detection, and are composed of, for example, ferrite, magnetic metal fine particle material, amorphous metal magnetic material, etc., which can operate stably up to high temperatures. ..

<< Third Embodiment >>
FIG. 11 is a diagram for explaining the configuration of the third wheel detector (third embodiment) according to the present invention.

As shown in the figure, the third wheel detector 1100 according to the present invention includes a transmission coil L1, a reception coil L2, an adjustment plate M, a tubular magnetic member D1, a magnetic plate D2, and a second magnetism. It is provided with a plate D3. The second magnetic plate D3 is arranged below the receiving coil L2 and at a position closer to the rail 10. The third wheel detector 1100 is obtained by adding a second magnetic plate D3 to the second wheel detector 1000 described above.

In addition to the magnetic plate D2, the second magnetic plate D3 is further inserted into the rail 10 side vertically below the receiving coil L2 to expand the operation of the magnetic flux balance in the flat coil when adjusting the magnetic plate D2. Can be done. After fixing the receiving coil L2, when a magnetic material having an area of about 20% of the area of the receiving coil L2 is used as the magnetic plate D2 and the magnetic plate D3, the magnetic plate D2 at the time of adjustment to make V2 approximately 0. The position operation can be performed over, for example, about 30 mm, which contributes to the efficiency of the adjustment work and the stable operation of the coil.

Like the tubular magnetic member D1 and the magnetic plate D2, the second magnetic plate D3 also needs to be suitable for the operating environment at the time of wheel detection. For example, ferrite or magnetic metal fine particle material capable of stable operation up to high temperature. , Amorphous metal magnetic material and the like.

<< Fourth Embodiment >>
FIG. 12 is a diagram for explaining the configuration of the fourth wheel detector (fourth embodiment) according to the present invention.

As shown in the figure, the fourth wheel detector 1200 according to the present invention includes a transmission coil L1, a reception coil L2, adjustment plates M1 and M2, a tubular magnetic member D1, a magnetic plate D2, and a second. The magnetic plate D3 of the above is provided.

In the present embodiment, the adjusting member for L1 magnetic flux correction is composed of two adjusting plates, that is, an adjusting plate M1 for coarse adjustment and an adjustment plate M2 for fine adjustment. The adjusting plates M1 and M2 are each configured to be able to adjust the angle of the plate surface with respect to the main shaft 901 of the transmission coil L1 by an angle adjusting mechanism (not shown).

The adjustment plate M1 for coarse adjustment is arranged at a position close to the transmission coil L1 and is responsible for most of the correction. On the other hand, the adjustment plate M2 for fine adjustment is arranged behind the adjustment plate M1 for coarse adjustment and is used for fine adjustment.

In the present embodiment, since the adjusting member for L1 magnetic flux correction is composed of two adjusting plates M1 and M2, the work when adjusting V2 at high S / N to 0 is performed at the installation site. Is even easier, and mounting reliability can be improved.

<< Fifth Embodiment >>
13 and 14 are diagrams for explaining the configuration of the fifth wheel detector (fifth embodiment) according to the present invention.

As shown in FIGS. 13 and 14, the fifth wheel detector 1300 according to the present invention includes a transmission coil L1, a reception coil L2, an adjustment plate M, a magnetic plate D2, and a compensation coil L3. The fifth wheel detector 1300 is a combination of the first wheel detector 900 described above, the magnetic plate D2, and the compensation coil L3.

The compensation coil L3 is composed of a flat coil like the reception coil L2.

The arrangement position of the compensation coil L3 is different between FIGS. 13 and 14. That is, FIG. 13 shows an example in which the compensation coil L3 is arranged so that the magnetic plate D2 is sandwiched between the receiving coil L2 and the compensation coil L3, and FIG. 14 shows an example in which the compensation coil L3 is sandwiched between the receiving coil L2 and the magnetic plate D2. As described above, an example in which the compensation coil L3 is arranged is shown.

As described above, the adjusting plate M and the magnetic plate D2 can minimize V2, and a high S / N can be obtained by adjusting only V1. However, in order to reduce the coil drive power, V3 is used. It is desirable to be small. Normally, a signal current (orbital current) of several tens of Hz to kHz flows through the rail for section control, etc., and when the L1 drive current is low and V1 is small or the orbital current level is high, The voltage from the magnetic flux Ψ2 caused by the current is superimposed on the detection voltage of the receiving coil L2 as signal noise, which causes a decrease in S / N. When there are wheels, the induced voltage due to the magnetic flux Ψ1 from the transmitting coil L1 penetrating the receiving coil L2 can be set to zero by the adjusting plate M, the magnetic plate D2, etc., but the orbital current is in space with the transmitting coil L1. Since it is an independent component, it does not match the condition of zero voltage component due to the magnetic flux Ψ2 with respect to the receiving coil L2.

In this embodiment, the compensation coil L3 is used to compensate for the contribution of the magnetic flux Ψ2. Since the detection voltage phase of the compensation coil L3 needs to match the detection voltage phase of the reception coil L2 in order for the compensation voltage to be effective, the compensation coil L3 is installed in the vicinity of the reception coil L2. As a result, the signal of the compensation coil L3 includes the induced voltage due to the magnetic flux of the transmission coil L1, and if it is left as it is, it causes an S / N decrease.

FIG. 15 is a diagram showing a configuration example of a signal processing system that processes the output signals of the receiving coil L2 and the compensation coil L3 in the wheel detector 1300.

As shown in the figure, the signal processing system 1500 includes a receiving coil L2, a compensation coil L3, a band elimination filter 1510, and a differential amplifier 1520.

The band-stop filter 1510 is for removing the signal of the drive frequency of the transmission coil L1 from the output of the compensation coil L3, and the output of the band-stop filter 1510 is the input of one (-) of the differential amplifier 1520. It is connected to the terminal.

The differential amplifier 1520 is for removing the influence of the orbital current from the output of the receiving coil L2, and is composed of, for example, an operational amplifier. The output of the receiving coil L2 is connected to one (+) input terminal of the differential amplifier 1520, and the output of the band elimination filter 1510 is connected to the other (-) input terminal of the differential amplifier 1520. The differential amplifier 1520 outputs a signal (voltage) proportional to the difference between the output signal (voltage) of the receiving coil L2 and the output signal (voltage) of the band removal filter 1510.

By using the signal processing system 1500 having the above configuration, the voltage due to the magnetic flux component of the transmission coil L1 can be excluded from the detection voltage of the compensation coil L3, whereby the reception coil does not decrease in S / N. It is possible to compensate for the influence of the orbital current included in the detection signal of L2.

Since the magnetic flux vectors at the positions of the compensating coil L3 and the receiving coil L2 have different curvatures for both Ψ1 and Ψ2, the elevation angle γ of the compensating coil L3 for compensating the orbital current magnetic flux has a value different from the elevation angle δ of the receiving coil L2.

As described above, according to the wheel detector described above, it is possible to realize a high S / N.

Further, once the positions and angles of the transmission coil L1 and the reception coil L2 are fixed, the subsequent adjustment to set V2 to almost 0 can be performed only by adjusting the elevation angle of the adjustment plate M and the horizontal position of the magnetic plate D2, which is practical. Time adjustment is simple. Further, since the magnetic flux shielding in which V2 becomes almost 0 is obtained as a detection signal only by the proximity of an object having a wheel size scale, the reliability of the wheel detection system is improved.

L1 Transmit coil L2 Receive coil L3 Compensation coil S Sensitivity area M, M1, M2 Adjusting plate D1 Cylindrical magnetic member D2 Magnetic plate D3 Second magnetic plate 10 Rail 11 Wheel movement direction 20 Wheels 21 Flange 41 Cylindrical coil 700 Flat type Coil 711,712 Flat coil 721,722 Electrostatic shield member 810 Upper flat coil 81 Winding start end 812 Winding end end 820 Lower flat coil 821 Winding start end 822 Winding end end 900 First wheel detector 901 Main shaft of transmission coil L1 1000 Second wheel detector 1100 Third wheel detector 1200 Fourth wheel detector 1300 Fifth wheel detector 1500 Signal processing system 1510 Band removal filter 1520 Differential amplifier

Claims (5)

A wheel detector equipped with a transmitting coil and a receiving coil arranged so as to sandwich a rail.
The receiving coil is composed of a flat coil.
The planar coil can approximately ignore the electromotive force generated by the magnetic flux that vertically penetrates the planar coil surface so as to follow the magnetic flux formed by the transmission coil , and the planar coil surface is approximated within the gentle magnetic flux diffusion surface. A wheel detector characterized by being placed in a position where it can be targeted. The wheel detector according to claim 1, wherein the flat coil is composed of a flat coil. The planar coil includes a plurality of the planar coils.
The wheel detector according to claim 2, wherein the plurality of flat coils are laminated. The wheel detector according to any one of claims 1 to 3, further comprising a metal plate for adjusting the magnetic flux of the transmission coil behind the transmission coil. The wheel detector according to any one of claims 1 to 4, wherein a magnetic member is further provided below the receiving coil.