JPS59160767A - Velocity detecting device - Google Patents

Abstract

PURPOSE:To prevent generation of mechanical resonance in movable part and to heighten accuracy by conforming the axial direction of a fixed coil with moving direction of an object to be measured and opposing wound face of the fixed coil to the pole of a permanent magnet. CONSTITUTION:A movable york 7 consisting of a magnetic body is provided in a movable body 6 that makes linear movement. A permanent magnet 8 is fixed to the movable body 6 through the movable york 7. A face of a fixed coil 9 opposes to N-pole of the permanent magnet 8, and the axial direction of the coil 9 is so arranged that it coincides with direction of moving of the movable body 6. A fixed york 10 penetrates the coil 9. The moving velocity of the movable body 6 can be detected from the counter electromotive force generated in the coil 9.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a speed detection device that non-contact detects the moving speed of a movable body that performs linear motion, such as a head transfer mechanism of a disk memory device or a robot arm. It is.

Conventional configurations and their problems In recent years, linear motion mechanisms such as the head transfer mechanism of disk memory devices, robot arms, etc. have been required to be faster, more precise, and smaller and lighter. .

Along with this, there has been a demand for speed detection devices during movement to have high responsiveness, a wide linear range, highly accurate output stability, and be smaller and lighter.

As such speed detection devices, devices of various types and shapes have been devised in the past.

Among these, differential transformer type devices are the most common. The configuration of the differential transformer type device will be explained below using FIG. 1. In FIG. Secondary coil, 5
is a detection circuit having diodes DI, D2, capacitors 01.02, resistors R1, R2, and pointer 5'. Note that the movable core 3 is attached to the object to be measured, and the other parts are fixed.

The operation of the apparatus configured as described above will be explained below. First, mutual induction acts between the primary coil 2 and the secondary coil 4, which are excited by the oscillator 1, via the movable iron core 3, and an induced voltage is generated in the secondary coil 4. At this time, the position of the movable core 3 can be detected by positionally dividing the secondary coil 4 and detecting the difference between the voltage between A and B and the voltage between B' and 0, and the differential output The velocity of the movable iron core 3, that is, the velocity of the object to be measured, is detected by differentiating with time using a differentiating circuit (not shown).

However, in the above configuration, if the range in which the output is linear is, for example, 60 In, the fixed side is approximately 150 tn.
m, and must have a length approximately several times longer than the measurement range.

In addition, a power source for the excitation oscillation g31 and a circuit such as a differential circuit are required, making the entire device unstable.

Furthermore, since the movable core 3 is attached to the object to be measured in an elongated cantilevered manner, mechanical resonance is likely to occur during movement, making it impossible to obtain a high control gain. Therefore, it is unsuitable as a speed detector for an optical disk head transport mechanism or a robot arm, etc., which require highly accurate speed control.

Purpose of the Invention The present invention solves the above-mentioned conventional problems, and makes the speed detection word length approximately equal to the measurement range, and also eliminates the need for a circuit such as an excitation oscillator, thereby reducing the size of the device. In addition, by creating a structure in which the movable member attached to the object to be measured is unlikely to cause mechanical resonance when moving, it is possible to obtain a high control gain. The present invention provides a speed detection device that can be used with high reliability even for objects.

Structure of the Invention The present invention provides a fixed coil that is fixed so that the coil axis direction coincides with the moving direction of the object to be measured, and a fixed coil that is attached to the object to be measured so that the winding surface of the fixed coil and the magnetic pole face each other. By providing a fixed permanent magnet, the device can be made smaller in relation to the measurement range, and a circuit such as an excitation oscillator can be made unnecessary. By using a magnet with a difficult shape, the control gain can be increased and highly accurate speed control can be achieved.

DESCRIPTION OF THE EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 2 and 3. FIG. 2 is a side view of the speed detection device according to the first embodiment of the present invention, and FIG. 3 is a plan view thereof. Third
4, 6 is a movable body that moves linearly in the direction of arrow x-x', 7 is a movable yoke made of a magnetic material provided on the movable body 6, and 8 is indicated by N and S in the figure. A permanent magnet having magnetism, 9 a coil wound into a rectangular shape, and 10 a fixed yoke made of a magnetic material.

Note that the permanent magnet 8 is fixed to the movable body 6 via the movable yoke 7, and moves in the directions of arrows x- and x' together with the movable body 6, which is the object to be measured. Further, the coil 9 is arranged such that one surface thereof faces the ON pole of the permanent magnet 8, and the axial direction of the coil 9 coincides with the direction of the arrow xx'. Furthermore, the fixed yoke 10 is arranged to penetrate the coil 9.

According to the above configuration, the magnetic flux generated by the permanent magnet 8 crosses the coil 9 and reaches the fixed yoke 10.

Now, there is a gearbox on the way, and let the magnetic flux density in that gear, Yap A, be Bg. Further, the moving speed of the movable body 6 is v, and the length of the coil in the gear A having a width a is n.

Therefore, when the movable body 6 moves at a speed V, that is, when the permanent magnet moves at a speed V, it is equivalent to a conductive wire relatively corresponding to the length of the coil 9 crossing a magnetic field with a magnetic flux density Bg at a speed V, From Faraday's law, E=BgVj! ! A back electromotive force is generated, and the moving speed V of the movable body 6 can be directly detected from this back electromotive force.

As described above, according to this embodiment, the length of the coil 9 is the sum of the length a of the permanent magnet 8 and the measurement range S, that is, the length a+
3, and the permanent magnet length a can be made sufficiently smaller than the measurement range S by, for example, increasing the winding density of the coil 9. Therefore, the overall length of the speed detector can be reduced to approximately the same extent as the measurement range S.

However, the speed signal can be directly detected by the back electromotive force in the form of E = 33gvi, so the power supply and excitation oscillator.

The entire device can be miniaturized without the need for a differential circuit or the like.

Furthermore, since the permanent magnet 8 is flat and does not easily generate resonance, a high control gain can be obtained, and it can be used in optical disk head transfer mechanisms, robot arms, etc. that require highly accurate speed control.

Next, a second embodiment of the present invention will be described using FIG. 4.

FIG. 4 is a side view of a speed detection device according to a second embodiment of the present invention. In FIG. 4, 6 is a movable body, 7 is a movable yaw shaft 1Q is a fixed yoke. 8' is a permanent magnet having a spherical surface and magnetic poles in the radial direction. Reference numeral 9' denotes a cylindrical coil, which is arranged so as to face the N pole formed on the spherical surface of the permanent magnet 8', and so that its coil axis substantially coincides with the direction of arrow x-x', which is the moving direction of the movable body 6. ing.

In the above configuration, if the magnetic flux density in the gear A is Bg, the coil group is 1, and the speed of the movable body 6 is ■, then E
A back electromotive force is generated at =BgVJl, and the same effect as in the first embodiment can be obtained. Furthermore, according to the second embodiment, by winding the coil into a cylindrical shape, the winding process is easier than with a rectangular coil.

Next, a third embodiment of the present invention will be described with reference to FIGS.

FIG. 6 is a side view of a speed detection device according to a third embodiment of the present invention, and FIG. 6 is a plan view thereof.

5 and 6, 6 is a movable body, 7 is a movable yoke, 8 is a permanent magnet, and 9 is a coil, which has the same structure as that shown in FIG. 2.

The difference from the configuration in Figure 2 is that the fixed yoke 1 is made of magnetic material.
0', a yoke member 10'a that passes through the coil 9, and a yoke member 10t that connects the yoke 1σa thereof and provides a gap B with the movable yoke 7.

This is the point formed by

With this configuration, the magnetic flux generated from the permanent magnet 8 passes through the fixed yoke 10' and the movable yoke 7, and
It reaches the magnet 8 and forms a closed magnetic path.

By forming the closed magnetic path as described above, for example, it is possible to make the movable body 6 less susceptible to the influence of an external magnetic field such as a leakage magnetic field from a drive motor, and to obtain a stable output.

Effects of the Invention As described above, the present invention provides a permanent magnet that is used as a movable object to be attached to an object to be measured and has a shape that does not easily generate mechanical resonance.
By providing a fixed coil whose magnetic pole and winding surface face each other, the overall length of the speed detector can be shortened by detecting the moving speed of the object to be measured from the generated back electromotive force. Since this circuit is not required, the device can be made smaller, and furthermore, since mechanical resonance is less likely to occur in the movable part, a high control gain can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional speed detecting device, Fig. 2 is a side view of main parts of a speed detecting device according to a first embodiment of the present invention, Fig. 3 is a plan view thereof, and Fig. 4 is a circuit diagram of a speed detecting device according to a first embodiment of the present invention. FIG. 6 is a side view of a main part of a speed detection device according to a second embodiment of the present invention, FIG. 6 is a side view of a main part of a speed detection device according to a third embodiment of the present invention, and FIG. 6 is a plan view thereof. 7...Movable yoke, 8,8'...Permanent magnet, 9°...Coil, 10110'...
...Fixed yoke. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3

Claims (1)

[Claims] (1) A fixed coil fixed so that the moving direction of a movable body that performs linear motion matches the coil axis direction, and a fixed coil fixed so that the winding surface of the fixed coil and its magnetic pole face each other. A speed detection device that includes a permanent magnet fixed to the movable body and detects the moving speed of the movable body in a non-contact manner.The G2 permanent magnet is a flat permanent magnet having magnetic poles in the thickness direction, and the fixed coil is The speed detection device according to claim 1, wherein the speed detection device is a rectangular coil wound in a rectangular shape, and is arranged so that one magnetic pole of the flat permanent magnet and one surface of the rectangular coil face each other. 3) The permanent magnet is a permanent magnet with a spherical surface and magnetic poles in the radial direction, and the fixed coil is a cylindrical coil.
The speed detection device according to claim 1, wherein the concave spherical surface of the permanent magnet and the winding surface of the cylindrical coil are arranged to face each other. (4) The speed detection device according to claim 1, wherein yokes each made of a magnetic material are arranged to form a closed magnetic path between the permanent magnet and the fixed coil.