JPH0139102Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to an improvement of a motor speed detection device used for detecting the speed of a small motor.

(b) Prior Art Conventionally, for example, in the case of a brushless motor, it has been possible to generate a frequency signal according to the rotation speed for the purpose of constant speed rotation control, and to process this frequency signal in a control circuit to control the rotation of the rotor. It is being done.

As methods for detecting the rotational speed of the rotor, optical detection and magnetic detection are known.

For optical detection, multiple holes are formed in an annular shape around the periphery of a disk attached to the rotor shaft of the motor, and light emitting diodes and phototransistors are placed facing each other to sandwich the holes. It detects and outputs intermittent light as a frequency signal.

In addition, magnetic detection systems are equipped with a rotor magnet disk, which generates leakage magnetic flux partially from a rotor yoke attached to the rotor shaft, and a secondary coil is placed on the outer periphery of the rotor yoke to detect rotation of the rotor yoke. Accordingly, leakage magnetic flux approaching the vicinity of the secondary coil is detected and extracted as a frequency signal.

However, in the case of optical detection, a light emitting diode and a phototransistor are statically opposed to each other, and it is necessary to separately provide a rotating body for passing and blocking light between them.

On the other hand, in the case of magnetic detection, the rotor is equipped with a magnet, which is a means of generating magnetism, so there is no need to separately provide the above-mentioned rotating body in the case of optical detection. Since it is used for various purposes, it is easily influenced by the magnetism of other magnetic circuits and has the disadvantage of being susceptible to magnetic and electrical noise that enters from outside the system.

(C) Purpose of the invention The present invention has been devised to solve the drawbacks of the conventional technology, and uses optical detection to reduce speed detection errors. The present invention aims to provide a speed detection device that does not necessarily require a rotating body.

(d) Structure of the invention In order to achieve the above object, the invention includes a stator, a rotor supported by the stator, a plurality of photoconductors provided on the end face of the rotor, and a plurality of photoconductors provided on the periphery of the end face of the rotor. a plurality of light-receiving elements arranged in a distributed manner to face each other, and one end of the plurality of photoconductors faces in the axial direction at the center of rotation of the rotor, and the other end faces in the radial direction of the end surface of the rotor. The light receiving element is characterized in that it can face the light receiving element.

(E) Embodiment FIGS. 1 and 2 are a sectional view and a schematic front view showing an embodiment of the present invention.

In FIG. 1, a rotor shaft 5 having a rotor yoke 4 to which a magnetic disc 3 is fixedly attached is pivotally supported by a bearing portion 2 of a stator 1. As shown in FIG.

A circuit board 6 is attached to the stator 1, and a drive coil for rotating the rotor yoke 4 and an electronic circuit (none of which are shown) for switching and operating the drive coil are arranged on the circuit board 6. .

A rotating body 7 is attached to the rotor shaft 5. The rotating body 7 is formed by embedding a plurality of optical fibers 8 linearly and radially from the center of rotation toward the periphery. When molding this rotary body 7 with synthetic resin or other materials, the optical fiber 8
It may be formed by embedding and molding radially.

The end face of the optical fiber 8 at the center of rotation of the rotating body 7 can be irradiated with light by an irradiation means (not shown).

As shown in FIG. 2, a plurality of phototransistors 9 as light-receiving elements are arranged on the circuit board 6 so as to be distributed outside the rotational periphery of the rotating body 7 toward the end of the optical fiber 8. Note that these phototransistors 9 are connected so that the output signals are combined.

Therefore, when light is irradiated toward the optical fiber 8 at the center of rotation of the rotating body 7, the phototransistor 9 detects the light from the optical fiber 8 at the periphery of the rotating body 7, and outputs a composite signal.

Note that the other configurations and rotational operations are similar to conventionally known brushless motors and general small motors.

This type of motor speed detection device detects the rotating body 7.
When the optical fiber 8 at the center of rotation is irradiated with light, the rotor shaft 5 rotates and the rotating body 7
When rotates, each time the end of the optical fiber 8 of the rotating body 7 comes in front of each phototransistor 9, an output signal is output from the phototransistor 9, and the signals from each phototransistor 9 are combined to increase the rotational speed of the rotating body 7. It becomes possible to extract a composite frequency signal corresponding to the .

This signal is input to the control circuit, processed, and fed back to the electronic circuit, causing the brushless motor to rotate at a predetermined speed.

In addition, although the rotating body of the present invention described above shows an example in which the optical fibers 8 are arranged in a linear radial pattern, it is also possible to arrange them in a curved radial pattern.

Furthermore, the invention is not limited to the configuration in which the optical fiber 8 is arranged so as to be buried, but the present invention can be achieved by arranging the photoconductors 10 in addition to the optical fiber 8 radially at predetermined intervals as shown in FIG. It is possible to achieve the goal.

Furthermore, the photoconductor can also be provided on the rotor yoke 4, in which case the special rotating body 7 can be omitted.

(f) Effects of the invention The motor speed detection device of the present invention is as follows:
A plurality of photoconductors that propagate light are arranged in a distributed manner facing the periphery of the end surface of the rotor, with one end facing the rotational center of the rotor in the axial direction and the other end facing the radial end of the end surface of the rotor. Since the sensor can face multiple light-receiving elements, it is not necessary to provide a rotating body between the light emitting source and the light-receiving element to pass and block light, unlike conventional optical speed detection devices. In addition, since one end of the plurality of photoconductors faces in the axial direction at the center of rotation, the light from the light emitting source can be propagated almost equally to the light receiving element, reducing variations in detection output between the light receiving elements. Moreover, it is not affected by magnetic leakage from other magnetic circuits, has the advantage of being strong against noise, and has great practical value.

[Brief explanation of the drawing]

1 and 2 are a cross-sectional view and a schematic partial plan view showing the motor speed detection device of the present invention, and FIG.
The figure is a sectional view showing another example of the rotating body according to the present invention. 1... Stator, 3... Magnetic disc, 4...
... Rotor yoke, 5 ... Rotor shaft, 6 ... Circuit board, 7 ... Rotating body, 8 ... Photoconductor (optical fiber), 9 ... Light receiving element (phototransistor).

Claims (1)

[Claims for Utility Model Registration] A stator, a rotor pivotally supported by the stator, a plurality of photoconductors provided on the end surface of the rotor, and a plurality of photoconductors distributed opposite to the periphery of the end surface of the rotor. a light-receiving element, wherein the plurality of photoconductors have one end facing in the axial direction at the center of rotation of the rotor, and the other end facing the radial end of the end surface of the rotor and facing the light-receiving element. A motor speed detection device characterized by the following.