JP6448233B2 - Sensor - Google Patents

Description

  The present invention relates to a technique for determining a traveling direction of a vehicle.

  There is a technique for determining that a train has passed a predetermined point and its traveling direction by detecting a change in magnetic field caused by the proximity of wheels. In order to determine the direction of the vehicle, for example, two sets of loop coils are arranged, and a change in inductance with time in each coil is detected (Non-Patent Document 1).

Internet, URL <http://www.fu-rex.co.jp/product1/ps_pst.html>, searched on June 26, 2014

However, with the conventional technology, it has been difficult to detect a vehicle having a small wheel diameter with respect to the coil installation interval while ensuring safety.
An object of the present invention is to detect a wheel having a small diameter with respect to a coil installation interval.

According to one aspect of the present invention, two pairs of a transmission coil and a reception coil that detect an approach of an object by detecting a change in a magnetic field using an alternating current of a predetermined frequency are arranged, and one reception coil and the other Is a sensor that determines the advancing direction of the object based on the detection order when a change in the magnetic field is detected in the receiving coil and a part of the detected period is common, and is detected by each receiving coil. There is provided a sensor having correction means for extending the period of at least one of the receiving coils so that an overlap occurs in the period of change in the phase of the magnetic field .
In another preferred aspect, the object is a vehicle traveling on a track, and the pair of transmission coils and reception coils are provided on both sides of one rail constituting the track, respectively.
In another preferred embodiment, when the one receiving coil detects a change in the magnetic field before the other receiving coil, the correction means detects the change in the phase of the magnetic field detected in the one receiving coil. The end point of the period is shifted backward, and the start point of the period of the phase change of the magnetic field detected in the other receiving coil is shifted forward .
In another preferred embodiment, the amount of shifting the end point of the change period of the magnetic field detected by the one receiving coil is generated in the other transmitting coil and detected in the one receiving coil. It is set based on the magnitude of the magnetic field.

  ADVANTAGE OF THE INVENTION According to this invention, a wheel with a small diameter is detectable with respect to the installation space | interval of a coil, ensuring safety | security.

The figure which shows the signal processing apparatus. The figure which shows the function of the sensor 800. (A) is an example of a signal before correction, and (b) is a diagram showing an example of a signal after correction. The figure which shows the outline | summary of the railway management system 990. FIG. The figure which shows the detail of the wheel detection part 200. FIG. The figure which shows the signal processing apparatus 199 concerning a prior art. The figure which shows the relationship between the advancing direction of a vehicle and the detected signal concerning a prior art. The example of the signal detected when a wheel diameter concerning a prior art is small.

First, a method for detecting the traveling direction of a railway vehicle according to the related art will be described with reference to FIGS.
FIG. 4 shows an outline of the railway management system 990. The railway management system 990 includes a wheel detection unit 200, a signal processing device 199, and a central management device 300. The railway vehicle travels on the track 400. Both directions of travel of the vehicle are possible. The vehicle includes any vehicle that can travel on the track 400, such as a maintenance vehicle and a truck, in addition to a normal passenger car. That is, in the railway management system 990, a plurality of types of vehicles can travel in either direction on the track 400. The wheel diameter (size) can be different for different types of vehicles. The track section (S (x)) defines a section set on the track 400.

The signal processing device 199 is an ACD (Axel count device) for detecting the passing and traveling direction of the vehicle, and one signal processing device 199 is provided at the boundary of the track section S. That is, each boundary portion of the track section S is a point where the passage and the traveling direction of the vehicle are detected. A signal detected by each signal processing device 199 is supplied to the corresponding wheel detection unit 200.
One wheel detection unit 200 is an AD (Axel detector), and one wheel detection unit 200 is provided corresponding to one signal processing device 199. One signal processing device 199 and one wheel detection unit 200 are electrically connected via a signal line. The wheel detection unit 200 applies an AC voltage to the signal processing device 199 and acquires a signal supplied from the signal processing device 199.
Only one central management device 300 is provided, and from all the wheel detection units 200, it is ascertained in which direction each point (boundary portion of the track section S) has passed, and which track section all trains have. Information on whether or not it exists in S and its traveling direction are collected and managed.

FIG. 5 is a diagram showing details of the wheel detection unit 200. The wheel detection unit 200 includes a transmission / reception circuit 205A and a transmission / reception circuit 205B.
The transmission / reception circuit 205A and the transmission / reception circuit 205B are structurally identical. Therefore, hereinafter, when it is not necessary to distinguish the two, they are simply referred to as “transmission / reception circuit 205”. Each transmission / reception circuit 205 includes a transmission coil 210 and a reception coil 220 that are installed facing each other across one rail R. In the transmission coil 210 </ b> A and the transmission coil 210 </ b> B, magnetic fields corresponding to the alternating currents having the frequencies f <b> 1 and f <b> 2 applied from the signal processing device 199 are generated. Part of the generated magnetic field penetrates into the receiving coil 220A and the receiving coil 220B, respectively, thereby generating an induced current. An electrical signal corresponding to the induced current is output to the signal processing device 199 from each of the receiving coil 220A and the receiving coil 220B.

Here, when an object such as a metal such as a wheel is not positioned between the transmission coil 210 and the reception coil 220, the phase of the current applied to the transmission coil 210 and the current output from the reception coil 220 are The phase remains constant and does not fluctuate.
However, if there is a metal object such as a wheel between the transmission coil 210 and the reception coil 220, the relationship between the phase of the current applied to the transmission coil 210 and the phase of the current output from the reception coil 220 (relative) Shift). Typically, the relative phase changes when the object approaches between the transmitting coil 210 and the receiving coil 220, and reverses when the object moves across and moves away. The traveling direction of the vehicle is determined using such a phase change detected by each transmission / reception circuit 205.

The traveling direction determination method will be specifically described with reference to FIGS.
FIG. 6 shows a circuit configuration of the signal processing device 199. The signal processing device 199 includes a phase difference detection circuit 110-1, a reference signal generation unit 140-1, a bandpass filter 120-1, a phase difference detection circuit 110-2, a reference signal generation unit 140-2, and a bandpass filter 120-. 2 and a determination circuit 130. The reference signal generation unit 140-1 and the reference signal generation unit 140-2 apply alternating currents having frequencies f1 and f2 to the transmission coil 210A and the transmission coil 210B, respectively, and reference signals Ref (f1) and Ref. As (f2), it outputs to the phase difference detection circuit 110-1 and the phase difference detection circuit 110-2. The phase difference detection circuit 110-1 and the phase difference detection circuit 110-2 respectively receive the signal R0 (f1) and the signal R0 (f1) from the reception coil 220A and the reception coil 220B, respectively. The phase difference (time change) from the reference signal is detected.

  The band pass filter 120-1 and the band pass filter 120-2 respectively extract only the frequency f1 and f2 components of the signal representing the phase difference. This is because the band pass filter 120-1 removes the influence of the magnetic field having the frequency f2 generated by the reception coil 220B on the reception coil 220A. Similarly, the band pass filter 120-2 is for removing the influence of the magnetic field having the frequency f1 generated by the receiving coil 220A on the receiving coil 220B. The signals output from the bandpass filter 120-1 and the bandpass filter 120-2 are supplied to the phase difference detection circuits 110-1 and 110-2, respectively.

  The determination circuit 130 compares the signal P1 and the signal P2 and generates a signal that indicates the degree of overlap between the two signals. The generated signal is output to the central management device 300. In the central management device 300, it is determined whether or not a phase shift has occurred, and if there is a partial overlap in a phase shift phase (inversion period), it is based on the order in which the inversion occurred. To determine the direction of travel. As a result, the central management device 300 grasps that the vehicle has passed in the wheel detection unit 200 and represents the traveling direction thereof.

  FIG. 7 shows the relationship between the traveling direction of vehicle 500 and the detected signal. When the vehicle travels from left to right as shown in FIG. 5A, the waveforms of the signals P1 and P2 are as shown in FIG. (B) represents that the phase is inverted in the period from time t1i to t1e. This means that one wheel of the vehicle entered the detection range of the transmission / reception circuit 205A at time t1i and escaped from the detection range of the transmission / reception circuit 205A at t1e. Similarly, this means that the wheel enters the detection range of the transmission / reception circuit 205B at time t2i and escapes from the detection range of the transmission / reception circuit 205B at t2e. The order in which the inversion is detected is the transmission / reception circuit 205A first and the transmission / reception circuit 205B later. The inversion periods detected by the transmission / reception circuit 205A and the transmission / reception circuit 205B overlap in the period from time t2i to t1e.

  FIGS. 3C and 3D show examples of signals obtained when the same vehicle travels in the reverse direction. (d) is the same as (b) in that there is an overlap in the inversion period, but the order in which inversion is detected is reversed. Thus, if the obtained signals P1 and P2 are compared, the traveling direction of the vehicle can be determined.

  Here, the existence of the overlapping section is a condition, for example, when a failure such as a detection error occurs at a certain moment and the inverted signal cannot be detected by only one of the transmission / reception circuit 205A and the transmission / reception circuit 205B. In the case of a normal train, the same vehicle has a plurality of axles (referred to as front wheels and rear wheels for convenience). This is because the detection order in 205A and 250B may be determined to be opposite to the actual traveling direction. A misjudgment of the direction of travel of a train can lead to a serious accident, so it must be reliably prevented. From this point of view, the railway management system 990 is designed not to determine the traveling direction because it is considered that some detection error has occurred when no overlap is detected.

However, in the case of a wheel having a diameter smaller than a certain value compared with L, no overlapping section occurs. This is because the length of the inversion period decreases as the wheel size decreases.
FIG. 8 is an example of a signal detected when the wheel diameter is small. As described above, in the conventional method, when the wheel diameter is small, there is a problem in that the traveling direction cannot be determined even though it can be detected that the vehicle has passed.
Even if L can be set small, there is a problem that the detection accuracy is lowered particularly in the detection when the wheel is large and the detection when the passing speed is large. In other words, it is difficult to determine the traveling direction of all the vehicles in a track in which vehicles having wheels of various diameters are mixed.

Hereinafter, the present invention will be described with reference to FIGS.
The system which is a premise in the present invention is the same as the railway management system 990. The difference from the railway management system 990 is that the signal processing device 100 is used instead of the signal processing device 199. Therefore, hereinafter, this difference will be mainly described.

  FIG. 1 shows a circuit configuration of the signal processing apparatus 100. The signal processing apparatus 100 includes a phase difference detection circuit 110-1, a phase difference detection circuit 110-1, a band pass filter 120-1, a band pass filter 120-2, a determination circuit 130, a reference signal generation unit 140-1, a reference signal. A generation unit 140-2 is included. The signal processing device 100 is different from the signal processing device 199 in that the signal processing device 100 includes a band-pass filter 125-1, a correction circuit 135-1, a band-pass filter 125-1, and a correction circuit 135-1. In other words, it can be said that the signal processing apparatus 100 has added a bypass circuit including the bandpass filter 125-1, the correction circuit 135-1, the bandpass filter 125-1, and the correction circuit 135-1 to the signal processing apparatus 199. This bypass circuit has a function of correcting the signal P1 and the signal P2 to the signal P1 ′ and the signal P2 ′, respectively. The operation in the determination circuit 130 is the same as that in the railway management system 990.

  The bandpass filter 125-1 removes frequency components other than f1 as with the bandpass filter 120-1. The bandpass filter 125-2 removes frequency components other than the frequency f2 as in the bandpass filter 120-2. The correction circuit 135-1 and the correction circuit 135-2 correct the input signals and output the signals as signals P1 'and P2'.

  FIG. 2 shows the function of the sensor 800. Sensor 800 includes a wheel detection unit 200 and a signal processing device 100. The wheel detection unit 200 is the same as the railway management system 990. The signal processing apparatus 100 includes a movement difference detection unit 820, a phase correction unit 830, and an overlap determination unit 840. The movement difference detection unit 820 is realized by the phase difference detection circuit 110-1 and the phase difference detection circuit 110-2 shown in FIG. 1, and is the same as the railway management system 990. The overlap determination unit 840 is realized by the determination circuit 130 illustrated in FIG. 1 and is the same as the railway management system 990. The phase correction unit 830 is realized by a bypass circuit including the band-pass filter 125-1, the correction circuit 135-1, the band-pass filter 125-1, and the correction circuit 135-1 shown in FIG. It is a function that does not.

  That is, as shown in the figure, the phase correction unit 830 detects the magnetic field detected in the receiving coil 220A based on the change in the magnetic field caused by the transmitting coil 210B detected by the receiving coil 220A. The change period is corrected, and the change period of the magnetic field detected in the reception coil 220B is corrected based on the change in the magnetic field caused by the transmission coil 210A detected by the reception coil 220B.

More specifically, correction as shown in FIG. 3 is performed. 3A shows an example of a signal before correction, and FIG. 3B shows an example of a signal after correction.
As shown in FIG. 5B, when the receiving coil 220A detects a change in the magnetic field before the receiving coil 220B, the phase correction unit 830 detects the phase of the magnetic field detected in the receiving coil 220A. The end point of the change period is shifted backward, and the start point of the change period of the magnetic field phase detected by the receiving coil 220B is shifted forward. When the order of inversion of the signals P1 and P2 is reversed, the end point of the phase change period of the magnetic field detected in the reception coil 220B is shifted backward, and the detection is detected in the reception coil 220A. Shift the start of the period of change of the magnetic field phase forward.

  In other words, when there is no overlap between the two inversion periods, the inversion period is extended for both the signal P1 and the signal P2 in the direction in which the overlap may occur. In the example shown in the figure, the two signals before correction are corrected so that there is no overlap period, and overlap occurs.

  The shift amount of the signal output from one transmitting coil (for example, the receiving coil 220A) is generated in the other transmitting coil (transmitting coil 210B), and is transferred to the one receiving coil (receiving coil 220A). Is set based on the magnitude (amplitude magnitude) of the detected frequency f2 magnetic field.

  According to the above embodiment, even if the same wheel detector 200 as the conventional one is used, it is possible to detect even a wheel having a smaller diameter. Therefore, it is possible to grasp the presence and traveling direction of a train on a track on which a vehicle in which wheels of different sizes are mixed is operated. Moreover, since only a bypass circuit is added to the conventional sensor system, it can be realized easily and at a lower cost than when a new sensor is manufactured from scratch.

The above embodiment is merely an example, and can be modified from various viewpoints.
For example, the signal to be corrected by the phase correction unit 830 may be at least one of the signals P1 and P2 instead of both. In short, at least one of a correction process in which the phase difference is detected earlier in time and the end point is extended backward in time, and a correction process in which the start point of the later detected is extended forward in time is executed. It only has to be done.
Further, the amount to be expanded (the length of time) may be a predetermined amount that is independent of the magnetic field, such as the signal strength of the receiving coil of the subject or the other party or the length of the inversion period.

  In addition, the application target of the present invention is not limited to a railway vehicle, and can also be applied to the determination of the traveling direction of an automobile or other moving body.

  The configurations, shapes, sizes, and arrangement relationships described in the above embodiments are merely schematically shown to the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the embodiments described above, and can be modified in various forms without departing from the scope of the technical idea shown in the claims.

DESCRIPTION OF SYMBOLS 100 ... Signal processing apparatus, 110 ... Phase difference detection circuit, 130 ... Determination circuit, 125 ... Band pass filter, 135 ... Correction circuit, 120 ... Band pass filter, 140 ... Reference signal generation unit, 300 ... central management device, 200 ... wheel detection unit, 400 ... track, 205 ... transmission / reception circuit, 210 ... transmission coil, 220 ... reception coil 820: Movement difference detection unit, 830 ... Phase correction unit, 840 ... Overlap determination unit, 800 ... Sensor, 990 ... Railway management system, 199 ... Signal processing device, 500. ··vehicle

Claims (4)

Two pairs of transmission coils and reception coils that detect an approach of an object by detecting a change in the magnetic field using an alternating current of a predetermined frequency are arranged, and a change in the magnetic field occurs in one reception coil and the other reception coil. A sensor that detects a traveling direction of the object based on a detection order when the detected period is partially common,
The sensor which has a correction means which extends the said period in at least any one receiving coil so that it may overlap in the period of the change of the phase of the magnetic field detected in each receiving coil . The object is a vehicle traveling on a track,
The sensor according to claim 1, wherein the pair of transmission coils and reception coils are provided on both sides of one rail constituting the line. When the one receiving coil detects a change in the magnetic field before the other receiving coil,
Wherein the correction means, the shifting back the end of the period of variation of one of the detected at the receiving coil a magnetic field in the phase, the start of the detected period of the change in phase of the magnetic field in the other receiver coil Shift the time forward,
The sensor according to claim 1 or 2.   The amount by which the end point of the change period of the magnetic field detected by the one receiving coil is shifted is generated by the other transmitting coil and is based on the magnitude of the magnetic field detected by the one receiving coil. The sensor according to claim 3, which is set as follows.

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