JPS60243526A - Apparatus for measuring axial force of rail - Google Patents

Abstract

PURPOSE:To make it possible to measure the stress in the axial direction of a rail, by differentially connecting magnetic anisotropy detecting coils so that disturbance magnetic fields are offset. CONSTITUTION:Detecting coils 17-1 and 17-2 of one magnetic anisotropy sensor 15-1 are cumulatively connected. Detecting coils 19-1 and 19-2 of another magnetic anisotropy sensor 15-2 are similarly connected. When the sensors 15-1 and 15-2 are arranged at an equal angle with respect to a rail, the voltages, caused by disturbance magnetic fluxes, which are induced in the detecting coils 17-1 and 17-2 and 19-1 and 19-2, become equal. When the coils 17-1 and 17-2 and 19-1 and 19-2 are differentially connected, the voltages are offset, and no output appears across output terminals 12. When exciting coils 18-1 and 18-2 are connected out of phase, the signal voltages, which are induced in the detecting coils 19- 1 and 19-2 become out of phase. Since the detecting coils 19-1 and 19-2 and 17-1 and 17-2 are differentially connected, the signals are added, i.e., the result is the twice the original voltage. Therefore, the detected signal of the degree of magnetization of the rail by the exciting coils of the sensors themselves becomes twice the original value. The disturbances are offset, and the proper signal can be positively detected.

Description

[Detailed description of the invention] [Field of application of the invention] 10 'l* RFI l→ kl 'F4.1:kl
m 64m 91ia nA hk ↓n r-l
Section 4 -1 This invention relates to a rail axial force measuring device that can measure the force without any effort.

[Background of the invention]

In recent years, the use of magnetic anisotropy sensors has been proposed as a method for nondestructively measuring stress in steel materials (for example, XS, kbwklL: :fapantzt:J
our own of Applied Physics,
? , vol. 16. A7゜1977, p1161
．． ) When a sample that has been well demagnetized in advance is excited with a constant alternating magnetic field using a magnetic anisotropy sensor that generates a relatively weak excitation magnetic field, the voltage output to the detection filter increases as the stress increases. , for compressive stress and tensile stress, the direction of the output voltage rectified in synchronization with the excited alternating current is reversed. (3 Haka Aiya, Institute of Electrical Engineers of Japan, Magnetics Research Group sample MAG-85-87.

(September 10, 1983) For example, the basic structure of a magnetic anisotropic sensor is shown in Figure 1 (Mountain 1) - 2 others, Journal of the Institute of Electrical Engineers of Japan B: 1984 4
197-203) Since there is something like this, the inverted U-shaped excitation core 1 and detection core 2 are orthogonal to each other. A pair of excitation coils 3 and a pair of detection filters 4 are arranged in the plane and wound around the n part. As these core materials, permalloy or the like is used, which has a much higher magnetic permeability than the magnetic material to be measured, that is, ordinary steel. When this is placed on the magnetic material to be measured, if the material does not have magnetic anisotropy or if there is an axis of easy magnetization in the plane of the excitation core, the magnetic flux due to the excitation coil will be as shown in Figure 2. As shown in (α), no output appears in the detection coil. However, 1-1.1-
2 is a leg of the excitation core, and 2-1.2-2 is a leg of the detection core. However, magnetic anisotropy exists in the magnetic material to be measured,
When the axis of easy magnetization is in the direction shown by arrow A in FIG. 2(A), the magnetic flux due to the excitation fill becomes as shown in FIG. 2Cb), and an output appears in the detection coil. The state shown in FIG. 2 (α) corresponds to the case where the resistances on each side of the known bridge circuit are balanced, and the state shown in FIG.
and 2-1 and between legs 1-2 and 2-2 can be treated as corresponding cases where the resistance is small.

Figure 3 shows the corresponding bridge circuit, and the resistances on sides 6-1 and 6-2, where arrow A crosses, are small), and the resistances on sides 6-3 and 6-4 are large, so that an output appears on detector 7. ing.

As shown in FIG. 4, a magnetic anisotropy sensor 8 is installed on the rail 9 in order to measure the axial force of the installed rail 9.
Assuming that, a current 10 that is a combination of train drive and signal currents flows through the 0 rail 9, and as a result, a magnetic field 11 according to the right-handed screw rule is generated. This magnetic field 11 causes a magnetic flux 11-1 in the excitation core 1, as shown in FIG.
, a magnetic flux 11-2 is generated in the detection core 2, and the output of the detection coil is large, exceeding the dynamic range of the amplifier and saturating it. This magnetic field 11 is a magnetic field generated by a current flowing through the rail, and is orthogonal to the axial direction of the rail, and is an excited magnetic field that is excited by a magnetic anisotropy sensor in order to measure the stress in the rail. This is a completely different disturbance magnetic field.

FIG. 6 shows the direction of the current 10 flowing through the rail 9, the direction of the magnetic field 11 generated by this current, and the directions of the excitation coil 1 and the detection coil 2. Figure 6 (α) shows the detection coil 2
shows a state where it is most susceptible to the influence of the disturbance magnetic field 11, and (h) in the figure shows a state where it is least affected.

In the magnetic anisotropy sensor shown in FIG. 1, the entire coil system consisting of an excitation coil and a detection coil can usually be rotated with respect to the object to be measured. Figure 7 shows the position where the detection coil does not produce an output due to the disturbance magnetic field, that is, Figure 6 (A
) is the starting point of the angle 1)-0, and the figure shows the relationship between θ and the detection coil output V when θ is rotated from 0 to 560 degrees. 13 indicates the detection coil output, 14 indicates the amplification output, and the detection It can be seen that the coil is affected by the disturbance magnetic field and the amplifier suddenly becomes saturated.

When measuring the rail axial force with a magnetic anisotropic sensor, the angle at which the rail axial force can be most easily detected is arranged so that the excitation coil and the detection core are arranged at approximately 45 degrees with respect to the rail. FIG. 7 shows that in the case of a detection coil, it is not possible to detect the presence of an axis of easy magnetization or the degree of ease of magnetization due to stress in the direction of the side bottom or rail axis.

[Purpose of the invention]

An object of the present invention is to provide an apparatus that can measure the axial stress of a rail using a magnetic anisotropy sensor without being affected by a disturbance magnetic field during actual measurement.

[Summary of the invention]

In order to achieve the above object, in the present invention, each of the rails is approximately perpendicular to the rail surface, and each is orthogonal to the rail by approximately 4.
A magnetic anisotropy sensor in which a coil is wound around an inverted U-shaped core whose legs are arranged in two planes forming a 5 degree angle with the legs in contact with the rail surface, with one side used for magnetic anisotropy detection and the other used for excitation. , 2 pairs! The core surfaces for magnetic anisotropy detection and the excitation core surfaces of these two sets of magnetic anisotropy sensors are parallel to each other, respectively, and the magnetic anisotropy detection coils are differentially connected to each other. Then, the disturbance magnetic field is applied to the two export coils and the two excitation coils in the six-piece coil with a flame are excited in opposite phases, and the two detection coils are differentially connected. Each output corresponds to the rail axial force. ◇Since the detection coils are connected differentially and the excitation coils excite in opposite phases, the outputs of the detection filters are in phase and added together. become.

Note that when measuring the rail axial force using a magnetic anisotropy sensor, there may be cases where the rail is in a particular condition, such as when various currents are being passed as described above, or because the rail is laid in a direction that is easily affected by the earth's magnetic field. Since the magnet is often magnetized in the running direction, it should be erased using a gradually decreasing alternating current magnetic field prior to measurement.

[Embodiments of the invention]

FIG. 8 is a schematic connection diagram of main parts of an embodiment of the present invention. The detection coil 171%17-2 of one sensor 15-1 is connected in a harmonic manner and can be regarded as one coil.

Detection coil 19-1.19-2 of the other sensor 15-2
The same is true. Now, when sensors 15-1 and 15-2 are installed at equal angles to the rail, the voltages due to the disturbance magnetic flux induced in detection coils 17-1 and 17-2 and 19-1 and 19-2 will be equal, Detection coil 17-1.1
If 7-2 and 19-1 and 19-2 are differentially connected, they will be canceled and the output of output terminal 12 will not appear. However, as it is, the excitation coils 16-1.16-2 and 18-1.18
-2 cancels out the original signal induced from the detection coil 1'? The signal voltages induced at -1 and 19-2 have opposite phases, and since these detection coils are differentially connected to the detection coils 17-1 and 17-2, the signals are summed and doubled. In this way, the detection signal of the degree of rail magnetization due to the excitation coil of the magnetic anisotropy sensor itself is doubled, and the disturbance is canceled out and the original signal is returned to normal. r'!
It is actually detectable.

By adopting this method, the disturbance is reduced to the sensor 15-1.
．． It is sufficient if it is equal to 15-2, and its direction 1 strength is irrelevant. Further, if the sensor 15-2 is used without excitation, disturbances can be canceled out, but the output signal will be the same as when using only one sensor. Note that, prior to measurement, it is desirable to sufficiently measure and calibrate the relationship between stress and output voltage using a sample made of the same material as the rail.

Note that it is also possible to realize the above-mentioned operation by a purely electrical method, which is shown in FIG. The voltage that is the sum of the signal detected by the sensor 15 and the disturbance is amplified by an amplifier 20 and converted to a DC voltage by a demodulator 21. This is held in the sample hold 23-1. Next, the switch 22 is reversed to create a non-excitation state, and only the disturbance voltage is similarly held in the sample hold 23-2, the difference is taken by the differential amplifier 24, and only the original signal can be output.

However, the drawback is that it cannot be used in cases where saturation occurs before demodulation (which often occurs).

〔Effect of the invention〕

As explained above, according to the present invention, the rail axial stress can be measured by the magnetic anisotropy detection device without being hindered by disturbances, amplifier saturation, or the like.

[Brief explanation of the drawing]

Figure 1 shows the basic structure of the magnetic anisotropic cross sensor.
Figures 2 (α) and (b) are diagrams explaining the operating principle of the magnetic anisotropy sensor, Figure 3 is a diagram of the bridge circuit corresponding to the magnetic anisotropy sensor, and Figure 4 is a rail using the magnetic anisotropy sensor. Explanatory diagrams of the axial force measurement state and the disturbance at that time, Figures 5 and 6 (
α), (h), Fig. 7 is an explanatory diagram of the causes and effects of disturbance, Fig. 8 is a schematic connection diagram of the main parts of an embodiment of the present invention, and Fig. 9 is a pure electric FIG. 3 is a diagram illustrating an example of a circuit that measures rail axial force while removing the influence of disturbance. 1... Excitation core 2... Detection core 3... Excitation coil 4... Detection coil 9... Rail 10... Current flowing in the rail 11... Disturbing magnetic field 15-1... One side magnetic anisotropy sensor 15-2...
The other magnetic anisotropy sensor 1 (S 1.10 2.18
1.18-2-...Excitation coil 17-1.17-2.1
9-1.19-2...Detection coil agent patent attorney Takashi
Akio Hashi Figure 1 Figure 2 (ρ) (shi) Sister 3 Continuation of Figure 1 page - @ Inventor Masayuki Ito @ Inventor Sugimura Personal interest 30 Hata, Kusho, Nakai-cho, Ashigarakami-gun, Kanagawa Prefecture Inside Hitachi Electronic Engineering Co., Ltd. 3001 Kusho, Nakai-machi, Ashigarakami-gun, Kanagawa Prefecture Inside Hitachi Electronics Engineering Co., Ltd.

Claims (1)

[Claims] Each coil is wound around an inverted U-shaped core whose legs are arranged in contact with the rail surface in two planes that are substantially perpendicular to the rail surface and mutually orthogonal, one for detecting magnetic anisotropy and the other for detecting magnetic anisotropy. Two sets of magnetic anisotropy sensors for excitation are arranged adjacently, and the core surfaces for magnetic anisotropy detection and the core surfaces for excitation of these two sets of magnetic anisotropy sensors are parallel to each other, respectively. , the magnetic anisotropy detection coils are differentially connected, the excitation coils are excited in opposite phases, and magnetic anisotropy corresponding to the rail axial force is generated in the rail. A rail axial force measuring device characterized in that the rail axial force is measured by removing the influence of a disturbance magnetic field by the output of a magnetic anisotropy detection coil.