JPH01257202A - Displacement detection - Google Patents

Abstract

PURPOSE:To determine a displacement of an object desired to detect a displacement, by bringing a magnetic detection means close or into contact with a magnetic material on the object being detected to detect a magnetic field change pattern formed on the magnetic material. CONSTITUTION:A magnetic reading unit 14a of a detector 14 for detecting a displacement of work 11 is brought close or into contact with the surface 12a of a magnetic material 12 on the work 11 to detect a magnetic change pattern of the surface 12a with Hall elements of the unit 14a. The magnetic change pattern detected is picked up as electrical signal with a signal processing/output device 4c while being converted into digital from analog and a displacement of the work 11 is detected as a change pattern of a magnetic flux density. Then, a waveform processing is performed thereby enabling determination of the displacement of the work 11 at a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for detecting the position or displacement of a workpiece or the like at a high V4 degree.

Conventional technology Wheel speed sensors, crank angle sensors, and other methods of magnetically detecting mechanical displacement in the driving state of a vehicle,
For example, in a conventional wheel speed sensor, as shown in FIG. A method of detection using a coil 6 is generally used.

Problems to be Solved by the Invention However, in the case of the conventional wheel speed sensor described above, since the hub rotor that is detected by the sensor is attached separately,
Installation requires space, and the position is detected from dynamic changes in magnetic flux density using a pickup coil.
At low speeds, the change in magnetic flux is small, making it difficult to detect the position, and when stopped, the magnetic flux does not change, making position detection impossible. Furthermore, since the spacing between the uneven teeth formed on the outer periphery of the hub rotor is as large as about 3 to 10 mm, there is a problem in that the detection resolution is low.

This enlightenment was made against the above-mentioned technical background.
The object of the present invention is to provide a displacement detection method that has little detection error and can easily detect positions at low speeds and when stopped.

Means to Solve the Problem As a means to solve the above problem, Komei's displacement detection method detects the displacement of a plurality of rows in which a plurality of spots each having a small area with a different magnetic field strength than the surrounding area are arranged in a nearly straight line. By arranging the spots in parallel in a direction crossing the displacement direction of the object and by making the arrangement pattern of the spots different in each row, a group of magnetic field change patterns is formed in advance on the displacement detection object, and the holes are A magnetic field change pattern formed on the displacement detection object is detected by a magnetic detection means such as an element array, a magnetoresistive element array, or a pickup coil, and the detected magnetic field change pattern is converted into an electric signal to detect the displacement detection object. It is characterized by finding the displacement of an object.

Effect According to the above method, a Hall element array is attached to the magnetic material on the object whose displacement is to be detected while it is moving or stopped.

A magnetic detection means such as a magnetoresistive element array or a pickup coil is brought close to or in contact with each other to detect the magnetic field change pattern formed in the magnetic material, and the detected magnetic field change pattern is converted into an electric signal depending on the strength of the magnetic field and displacement is detected. Find the displacement position of the object to be detected.

EXAMPLE Hereinafter, an example of the method of the present invention will be explained based on FIGS. 1 to 4.

1 to 3 show a first embodiment, in which the upper surface of a flat steel workpiece 11 is made of Fe-A I-N.
A magnetic material 12 such as a 1-Co alloy is overlay-welded using, for example, a CO2 laser beam, and its surface 12a is ground into a smooth plane.

Then, after magnetizing the entire magnetic material 12 so that the surface magnetic field becomes uniform, the surface 12a of the magnetic material 12 is magnetized.
By irradiating the irradiated area with CO2 laser light or YAG laser light, etc. focused on the area, the irradiated area is locally demagnetized by heating it above the Gurie temperature, and the surrounding area (the shaded area in Figure 1) is A demagnetized portion 13 of a minute area treated to have a different magnetic field strength is formed on the surface 12a of the magnetic material 12, and a demagnetized portion 13 of a minute area treated to have a different magnetic field strength from the surrounding area is formed on the surface 12a of the magnetic material 12. 11
They are arranged in a direction perpendicular to the direction of movement (the direction of the arrow in FIG. 1), and are formed in a plurality of rows with different arrangement patterns.

On the other hand, the detector 14 that detects the displacement of the workpiece 11 in this displacement detection method includes a magnetic reading unit 14a in which 5@ Hall elements are arranged in a row, and a lead wire 14b from each Hall element of the magnetic reading unit 14a. The magnetic reading unit 14a is configured to read the displacement of the workpiece 11 in the moving direction with a resolution of 4 bits remaining after sampling.

When detecting the displacement of the workpiece 11, the magnetic reading unit 14a of the detector 14 is brought close to or in contact with the surface 12a of the magnetic material 12 on the workpiece 11,
The magnetic field change pattern formed on the surface 12a is detected by each Hall element of the magnetic reading unit 14a.

The detected magnetic field change pattern is processed by the signal processing/output device 1.
4c as an electrical signal and A/D
For example, the demagnetized portion 13 of the minute area is converted to a signal level of 1, and the other portions that are not demagnetized are converted to a signal level of O (or conversely, the demagnetized portion 13 is set to a signal level of 0, and the other portions are converted to a signal level of 0. As the signal level 1), the second
As shown in the figure, the displacement of the workpiece 11 is detected as a change pattern of magnetic flux density, and the waveform processing is performed as shown in FIG. 3, so that the displacement position of the workpiece 11 can be determined with high precision.

Therefore, in the displacement detection method of the first embodiment, since the magnetic reading unit 14a in which a plurality of Hall elements are linearly arranged is provided as the magnetic detection means, it is possible to detect the Displacement can be detected even when stopped.

Further, in this embodiment, the magnetic material 12 was built up using a laser beam, but a plate-shaped magnetic material may also be provided by welding, adhesion, vapor deposition, or the like.

FIG. 4 shows a second embodiment, which is a method using the detector 14 used in the first embodiment.

On the top surface of the flat workpiece 21, Fe-Al-H
A magnetic material 22 such as an l-Co alloy is overlay-welded using a CO2 laser beam, and its surface 22a is polished to a smooth finish.

Then, the magnetic material 22 is locally applied with a magnetic field by bringing a magnetizing electromagnetic coil or the like close to its surface 22a, and at the same time, the CO2 laser beam, YAG laser beam, etc. focused on the surface 22a is applied to the magnetic material 22. A magnetic field is applied to a given area and the area is heated to a high temperature close to or even higher than the magnetic transformation point. When the part to which the magnetic field is applied is heated to a high temperature close to the magnetic transformation point or higher, the magnetic domains in the magnetic material 22 tend to change direction due to thermal vibration, and as a result, the part heated by the laser beam irradiation Only the magnetic field is locally magnetized, and a magnetized portion 23 with a minute area is formed with a magnetic field strength different from that of the surrounding area. Then, on the surface 22a of the magnetic material 22, a magnetized portion 23 of a minute area, which is similarly formed to have a field strength of 11 different from the surrounding area, is formed in the direction of movement of the workpiece 21 (in the direction of the arrow in FIG. 2). They are arranged in a plurality of rows in the same arrangement pattern as the stone eraser portions 13 formed on the surface 12a of the magnetic material 12 in the first embodiment. Then, as in the case of the first embodiment, the magnetic reading unit 14a of the detector 14 is brought close to or in contact with the surface 22a of the magnetic material 22 on the workpiece 21, and each Hall element of the magnetic reading unit 14a is surface 22
Detects the magnetic field change pattern formed in a, and performs signal processing and
The output device 14c outputs an electrical signal and A/D converts it, so that, for example, the small-area magnetized portion 23 is set to signal level 1, and the other non-magnetized portions are set to signal level 1 and signaled by a bell O (or On the contrary, the magnetized part 23
If the signal level is O and the other parts are detected as signal level 1), the displacement of the workpiece 21 during movement, at low speed, and at rest can be detected with high accuracy, as in the case of the first embodiment. can do.

In addition, in the above-mentioned hanging embodiment, the flat workpiece 11.
Although the case where the displacement detection of 21 is performed has been described, if a magnetic material is built up on the surface of the crankshaft and a magnetic field change pattern is formed, the displacement of the crank angle can be detected in the same way.

Further, as another method for forming a magnetic field change pattern on the surface of a workpiece, etc., there is a method in which, for example, magnetic film pieces, magnetic rubber pieces, etc. are adhered in different arrangement patterns.

As described in detail, the displacement detection method of the present invention detects a plurality of rows in which a plurality of spots each having a small area having a magnetic field strength different from the surrounding area are arranged in a substantially straight line, with respect to the direction of displacement of the dye to be detected. By arranging the spots in parallel in intersecting directions and making the arrangement pattern of the spots different in each row, a group of magnetic field change patterns is formed in advance on the object to be detected for displacement. The magnetic field change pattern formed on the displacement detection object is detected by a magnetic detection means such as a pickup coil, and the detected magnetic field change pattern is converted into an electric signal to determine the displacement of the displacement detection object. Since the displacement of the object to be detected can be directly detected, by eliminating mechanical transmission parts such as gear meshing parts on the detector side, measurement errors caused by backlash etc. can be reduced, allowing for highly accurate displacement detection. becomes possible. Further, if a Hall element or a magnetoresistive element is used as the magnetic detection means, it is possible to detect the displacement of the displacement detection object at low speed and at a stop.

[Brief explanation of the drawing]

Figures 1 to 3 show the first embodiment of the method of this Komei. Figure 1 is a perspective view showing a state in which displacement is being detected, and Figure 2 is a perspective view showing a state in which displacement is being detected. A graph converted into a signal and output, Fig. 3 is a graph obtained by waveform processing of the amount of change in magnetic flux density shown in Fig. 2, and Fig. 4 is a perspective view showing the state in which displacement detection is performed in the second embodiment. FIG. 5 is an explanatory diagram showing a conventional example. 11.21... Workpiece, 12.22... Magnetic material, 12a, 22a... Surface, 13... Demagnetizing portion, 14... Detector, 14a... Magnetic reading unit, 23... ... Magnetized portion 1゜ Applicant Toyota Motor Corporation Agent Patent Attorney Yutaka 1) Takehisa (and 1 other person) Section 1 4c 14c Figure 4 Figure 2 Figure 3 Attenuation 1 Figure 5

Claims (1)

[Claims] A plurality of rows in which a plurality of spots with a small area of magnetic field strength different from the surroundings are arranged in a substantially straight line are arranged in parallel in a direction intersecting the displacement direction of the displacement detection target, and the spots in each row are By making the arrangement patterns different, a group of magnetic field change patterns is formed in advance on the displacement detection target object, and by magnetic detection means such as a Hall element array, a magnetoresistive element array, or a pickup coil,
A displacement detection method, comprising detecting a magnetic field change pattern formed on the displacement detection object, converting the detected magnetic field change pattern into an electric signal, and determining the displacement of the displacement detection object.