JPS6322273B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a point detection device that electromagnetically detects a metal object provided at a predetermined point on a track on a vehicle.

Currently, in the track maintenance departments of Japanese National Railways, track deviations are measured using track inspection vehicles, and the measured data is recorded on pen-written chart paper and, if necessary, recorded in a data recorder. At this time, it is absolutely necessary to accurately include so-called distance marks in the recorded data.
Maintenance work such as defective areas is performed based on the recorded distance marks.

The above-mentioned distance mark has conventionally been created by extracting pulses at constant distance intervals from a pulse generator directly connected to the axle and integrating the pulses with a pulse counter. However, there is a risk that errors may occur and accumulate due to wear of the vehicle diameter or vehicle slippage, and once they occur, they remain until the final point. For example, in the case of Shinkansen track inspection cars, if the error is 0.1%, then for a total length of 1000 km, the position error would be 1 km, making track maintenance based on measured data completely impossible.

In order to eliminate such inconveniences, on the Shinkansen, reflectors 3 are installed on the sleepers 2 of the rails 1 at intervals of a certain distance, for example, 1 km, as shown in Figure 1a.
On the other hand, as shown in Fig. 1b, a light emitter 6 and a light receiver 7 are provided on the bogie frame 5 of the inspection vehicle, and the point signal is obtained optically, and the integrated value of the pulse counter is corrected and maintained. This allows accurate distance marks to be recorded on chart paper.

However, the above-mentioned optical point detection device has a serious drawback in that the reflective plate 3 loses its function due to winter rain and snow accumulation, and the reflective plate 3 must be cleaned or cleaned in a timely manner to maintain its function even outside of winter. It requires adjustment of the optical axes of the light projector 6 and light receiver 7, and although it has a simple configuration, it has the disadvantage that it is not necessarily easy to maintain its functionality.

This invention was made to completely eliminate the drawbacks of the above-mentioned optical point detection device.
The purpose is to provide a point detection device based on an electromagnetic method that operates stably throughout the year, regardless of rainfall or snowfall.

The main point of this invention is based on the principle of a differential transformer, which will be explained in detail below.

Figure 2a shows a differential transformer 8 (three-stage type) that electromagnetically measures the displacement of an object in a mechanical device, etc.
In this cross-sectional view, a core 11 made of a magnetic material is inserted into a hollow bobbin 8a in a movable state in the direction of arrow A (axial direction), and the outer circumference of the bobbin 8a is divided into three sections, with a primary coil 9 in the center. , secondary coils 10a and 10b are provided at the upper and lower parts of the figure, and the secondary coils 10a and 10b are differentially connected to each other as shown in FIG. 1b. When a current of an appropriate frequency is passed through the primary coil 9, a differential voltage υ between the induced voltages of the secondary coils 10a and 10b is outputted, which is why it is called a differential transformer.

Now the center of the core 11 is the secondary coil 10a, 10
When the core 11 is at the center position (x = 0), the output voltage υ = 0 due to symmetry, but when the core 11 moves from the -x side to the +x side, the induced voltage of the secondary coils 10a and 11b changes. A difference occurs and the output voltage becomes the second
A waveform shown by curve A in Figure c is obtained. When so-called synchronous detection is performed on this waveform using a current having the same frequency from the power supply 12 as the current flowing through the primary coil 9, a voltage shown in curve C is obtained. This invention will be described in detail below with reference to FIGS. 3a to 8.

As shown in FIGS. 3a and 3b, a test object 15 made of a magnetic material is provided on the track, and an excitation coil 13 corresponding to the primary coil 9 and detection coils 14a and 14b corresponding to the secondary coil 10 are mounted on the vehicle. By providing this, a detection signal of curve C in FIG. However, since there is a switch (point) part of rail 1 on the track, and rail 1 is a magnetic material, the above method inevitably detects rail 1 at the point part, and this does not correspond to the point detection signal. There is a high possibility that it will be a false signal. Therefore, in order to eliminate this erroneous signal, we will further study the principle of the differential transformer and make improvements. That is, in the above description, the core 11 shown in FIG. 2a is made of a magnetic material, but if it is made of a non-magnetic metal such as aluminum and the characteristics of the output voltage υ are examined, in this case, the core 11 shown in FIG. It has been found that curve D has the opposite polarity to curve C for magnetic materials.

It is a remarkable feature that the output voltage waveform shows completely opposite phases depending on whether the core of the differential transformer is magnetic or non-magnetic (metal). Let's consider the reason.

Now, in FIGS. 3a and 3b, even if there is a specimen 1 between the excitation coil 13 and the detection coils 14a and 14b,
Even if 5 is not present, a certain degree of magnetic coupling exists as a so-called air-core coil, forming a differential transformer. When the test object 15 is a magnetic material, the magnetic resistance between these coils decreases and the magnetic coupling increases. Therefore, in this case, when the position of the test object 15 is biased to either side from the center, for example on the -x side in FIG. The detection coil 14b is smaller, and as a result, the differential voltage becomes positive on the -x side, as shown by curve C in FIG. 3c, for example. It is clear that when the test object 15 is biased toward the +x side, the differential voltage has the opposite phase to the above.

On the other hand, if the test object 15 is a non-magnetic metal such as aluminum or copper, the coupling between the excitation coil 13 and the detection coils 14a, 14b is rather reduced due to the eddy current effect that occurs within this metal. It is interpreted that this results in a phenomenon in which the output voltage υ becomes out of phase as described above.

In this invention, a test object 15 made of non-magnetic metal such as aluminum is placed at a predetermined point on the orbit.
An excitation coil 13 made of an air-core coil and differentially connected detection coils 14a, 1 are installed on the vehicle.
4b is provided, and the polarity of the detection signal obtained from this is determined to remove erroneous signals caused by the rail etc.
It is capable of outputting a correct point detection signal.

Considering the axial directions of the excitation coil 13 and the detection coils 14a and 14b (hereinafter simply referred to as each coil) in the above explanation, in FIG. Direction of vehicle travel (arrow B
). On the other hand, the fourth
In figure a, the axial direction of each coil is perpendicular to the direction of travel of the vehicle. However, even in this case, as shown in FIG. 4b, magnetic coupling is effected between the coils by the lines of magnetic force H, so that a differential transformer can be constructed. Therefore, the axial direction of each coil is quite arbitrary, and can be any direction as long as a differential transformer can be constructed.

Next, looking at the configuration of the differential transformer from the point of view of noise removal, the detection coils 14a, 14
A noise voltage is induced at b. In this case, the induced voltages of both detection coils 14a and 14b are equal (amplitude,
One of the advantages of this method is that the signal-to-noise ratio increases because the noise voltage is significantly reduced even when the induced voltages are unequal, and the noise voltage is significantly reduced even when the induced voltages are unequal.

The coil specifications such as the diameter, length, and number of turns of each coil, as well as the arrangement spacing of each coil, depend on the material and size of the test object 15 and the test object 1.
The optimum value can be determined through experiments, etc., taking into consideration the possible distance intervals between the coils.

More specific embodiments of the present invention will be described in detail below with reference to FIGS. 5 to 8. Fig. 5 shows an embodiment of the installation arrangement of the vehicle point detection device according to the present invention, in which a non-magnetic material such as an aluminum plate or a copper plate is installed in the center of the sleeper 2 (the center between the left and right rails) at a desired point on the track. A test object 16 made of a metal material is provided. In the figure, the test object 16 is "ko"
The structure is bent into the shape of a letter, but this is not necessarily the case. Generally, the eddy current effect is limited to the vicinity of the surface by setting the operating frequency to an appropriately high value, so a non-magnetic metal plate such as an aluminum plate of an appropriate thickness can be used. .

Next, a point detection sensor 17 consisting of an excitation coil 13 and a detection coil 14 is attached to a suitable location on the trolley 5 of the inspection vehicle, facing the object 16 to be inspected. It goes without saying that the bottom surface of the point detection sensor 17 should be maintained at a specified height above the rail surface in accordance with the vehicle limits. The axial direction of each coil inside the detection sensor 17 may follow the above-mentioned theory. It is also desirable that each coil, wiring, etc. have a moisture-proof structure using a molding method or the like.

With the arrangement of the test object 16 and the detection sensor 17 described above, the waveform of the point detection signal shown in FIG.
A detection signal is also output for the rail 18a or rail 18b marked with a circle at the point in the figure.
This is shown in waveform C in FIG.

FIG. 8 shows an embodiment of the general book structure of the point detection device according to the present invention, in which the oscillator 12 generates a sine wave of the above-mentioned appropriate frequency and supplies it to the excitation coil 13. Noise is removed from the differential output voltages of the detection coils 14a and 14b by a wave detector 19, and synchronous detection is performed by a synchronous detector 20. The output of the synchronous detector 20 is waveform C or waveform D in FIG. 7, but is shaped by the polarity discriminator 21 to become a pulse C' and a pulse D, respectively, and it is logically determined whether these pulses are correct or incorrect. That is, the logic circuit identifies and selects the pulse N' which is temporally negative first and positive later, and is determined to be a correct signal, and the point detection signal S is output. It goes without saying that pulses H' which are positive first and negative later, as well as invalid pulses due to noise other than these, are rejected.

In the above configuration, when the traveling direction of the vehicle is reversed (upward/downward relationship), waveforms C and D in FIG. A switch 23 is provided to make a correct logical judgment corresponding to the traveling direction of the vehicle and to always output a correct point detection signal.

As is clear from the above explanation, since the vehicle location detection device according to the present invention basically uses an electromagnetic method, it can be expected to operate without any problems even under various weather conditions including snowfall. be. In addition, we have captured the remarkable feature that the phase of the output voltage is reversed depending on whether the core material of the differential transformer is magnetic or non-magnetic metal. By doing so, we devised a method to eliminate false signals caused by rails, thereby providing a stable and highly reliable point detection device. In addition, each part of the device has a simple structure, is highly reliable, and is highly economical, and maintenance work during use is significantly reduced compared to the optical type. be.

[Brief explanation of the drawing]

Figures 1a and b are explanatory diagrams of a conventional point detection device for a vehicle. Figure 1a is a diagram showing the relationship between a reflector installed on the track and the rail, and Figure 1b is a diagram showing the relationship between a reflector installed on a track and a rail. Figures 2a, b and c are all diagrams explaining the principle of a differential transformer, and Figures 3a, b to 8 are all examples of the present invention. Figures 3a and 3b are respective layout diagrams of the detection sensor section and the object to be detected in the vehicle point detection device, Figure 3c is a waveform diagram of the detection signal in Figure 3a, and Figure 4a , b are diagrams explaining the arrangement of excitation coils and detection coils in a vehicle point detection device, FIG. An explanatory diagram of the vicinity of a point on a rail, FIG. 7 is a detection signal waveform diagram in a vehicle point detection device, and FIG. 8 is an overall block diagram of the vehicle point detection device. 1...Rail, 2...Sleeper, 3...Reflector, 4...Wheel, 5...Dolly (frame), 6...Emitter, 7...Light receiver,
8... Differential transformer, 9... Primary coil, 10... Secondary coil, 11... Core, 12... Oscillator, 13... Excitation coil, 14... Detection coil, 15... Metal test object,
16... Test object, 17... Detection sensor section, 18a, 1
8b...Point rail, 19...Wave, 20...
Synchronous detector, 21... Polarity discriminator, 22... Signal output terminal, 23... Up/Down switching switch.

Claims (1)

[Claims] 1. A test object made of a non-magnetic metal plate is provided at a specific position between the left and right rails at a fixed distance interval on the track, and the test object is mounted on the trolley of a track inspection vehicle. A point detection device for a vehicle, characterized in that a differential transformer including an excitation (primary) coil and a set of detection coils is provided at opposing positions to detect the presence or absence of the object to be inspected. 2. The vehicle point detection device according to claim 1, characterized in that the non-magnetic metal plate is bent into a U-shape. 3. The vehicle point detection device according to claim 1, wherein the excitation coil and the detection coil are comprised of air-core coils. 4. A vehicle according to claim 1, wherein the differential transformer according to claim 1 is disposed in a casing made of non-magnetic, non-metallic material and having an airtight and moisture-proof structure. Point detection device.