JPH10318788A - Multiple rotation encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive multiple rotation encoder having long service life in which backup power supply is eliminated and gear noise is eliminated except the bearing. SOLUTION: The r.p.m. detection means for a multiple rotation encoder comprises an inner rotor 1 provided with a magnet 12 having poles equal to an integer of 2 arranged while altering the polarity on the outer circumference of a soft magnetic tube 11 being born rotatably, a plurality of outer rotors 21-23 supported rotatably and coaxially on the outside of the inner rotor through a magnetic modulation means while having a plurality of annular yokes 61-63 made of a soft magnetic material with a specified number of magnets 3, equal to an integer of 2, being arranged while altering the polarity on the inner circumference of each yoke having the outer circumference arranged with magnets being magnetized in M series, and a plurality of magnetic detection means 8 arranged through an air gap on the outer circumference of each outer rotor. Multiple number of revolutions are detected by combining a plurality of magnetic detection signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detecting device for detecting a multi-rotation amount of a servomotor used for a robot or a machine tool by an absolute angle, and more particularly to a battery-less multi-rotation encoder which does not require an external power supply. .

[0002]

2. Description of the Related Art Conventionally, this kind of rotation speed detector has a reduction gear mounted on a rotation shaft, and detects the rotation angle after deceleration with an encoder or a potentiometer, or detects the rotation speed from an encoder signal and counts it with a counter. And other methods are used. Further, as disclosed in JP-A-62-238414, there is a method of storing the number of revolutions using a magnetic bubble element.

[0003]

However, since the system using the reduction gear has a mechanical rotation transmitting unit,
Noise due to gears is generated, and it is difficult to detect with high accuracy due to the influence of backlash and the like, and the structure is complicated and reliability is reduced. In addition, the method of counting the number of revolutions requires a backup power supply so that counting can be performed even when the power supply is cut off, and there is a problem that the controller becomes larger and the power cutoff period is limited due to the life of the backup power supply. . In addition, there is a problem that the method using the magnetic bubble is very expensive. In view of the above disadvantages of the prior art, an object of the present invention is to eliminate the need for a backup power supply when power is cut off, and to provide high reliability without mechanical contact parts except for bearings and no noise such as gear noise. An object of the present invention is to provide an inexpensive multi-rotation encoder with a long life.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a multi-unit comprising an absolute value encoder for detecting an absolute value angle within one rotation and a means for detecting a rotation amount. In a rotary encoder, an inner rotor in which magnetic poles having a different number of poles that are an integral multiple of 2 are alternately arranged on the outer periphery of a cylinder that is coaxially supported with the absolute value encoder,
The inner rotor has a plurality of annular yokes that are coaxially and rotatably supported on the outer side via magnetic modulation means and are made of a magnetic material. The inner circumference of each rotor has a different predetermined number that is an integral multiple of two. A number of magnetic poles are arranged adjacent to each other and have different polarities, and a magnet is arranged on the outer periphery of each rotor, and the outer rotor is magnetized so that the magnet becomes an M series. In contrast, a plurality of magnetic gears in which the outer rotor rotates at a predetermined reduction ratio are provided, a plurality of magnetic detection means are provided on the outer periphery of each outer rotor via a gap, and a memory wheel is configured with magnets on the outer periphery of each outer rotor. Then, the multi-rotation amount is detected from the signal of the memory wheel.

With the above structure, a plurality of outer rotors are rotated at predetermined different reduction ratios by the inner rotor of the magnetic gear rotating integrally with the rotating shaft, and the number of rotations can be detected by the memory wheel provided on the outer periphery of the outer rotor. This eliminates the need for a backup power supply when the power is cut off, and provides a highly reliable multi-rotation encoder that has no mechanical contact parts except for bearings, has no noise such as gear noise, and has a long life and is inexpensive.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B are diagrams showing a configuration of an embodiment of the present invention. FIG. 1A is a longitudinal sectional view of the configuration of the embodiment, and FIG. 1B is a cross-sectional view taken along a dotted line of FIG. In FIG. 1, an inner rotor 1 has magnets 12 of an integral multiple of 2 on the outer circumference of a soft magnetic cylinder (yoke) 11 supported on both sides by bearings 4 so that adjacent magnetic poles alternately have different poles. Placed in
The rotation is directly connected to the absolute value encoder 10. At an outer position of the inner rotor 1, an inductor 5 which is a magnetic modulating means having a number of teeth λ and made of a soft magnetic material is fixed via a gap. The teeth of the inductor 5 are located between the permanent magnets 12 of the inner rotor 1 and the permanent magnets 3 of the outer rotor, and play a role of magnetic modulation.

A plurality of annular yokes 61, 62, made of a soft magnetic material are supported on bearings 71, 72, 73 independently rotatably on the outer periphery of the inductor 5 coaxially with the inner rotor. 63 is an outer rotor in which a predetermined number of different magnets 3 each of which is an integral multiple of 2 are arranged on the inner periphery of each yoke such that adjacent magnetic poles are different from each other. Each of the annular yokes 61 to 63 constitutes a plurality of magnetic gears that rotate at a predetermined reduction ratio with respect to the rotation of the inner rotor 1 via magnetic coupling. The soft magnetic material forming the soft magnetic yoke 11 and the annular yokes 61 to 63 may be a solid material or a laminated magnetic steel plate. Now, if the number of pole pairs of the outer rotors 21 to 23 is P0, the number of pole pairs of the inner rotor 1 is Pi, and the reduction ratio of the magnetic gear is ギ ヤ, the following equation is established.

P0 = Pi · χ (1) λ = P0−Pi = Pi (χ−1) (2) In addition, magnetic projections 64 form an M-sequence pattern on the outer periphery of each of the annular yokes 61 to 63. It is arranged as follows. Further, in order to detect magnetic protrusions of the respective annular yokes 61 to 63, a plurality of magnetic detecting means 8 are provided via a gap. An M-sequence is a calculation method for continuously arranging numerical values so that repetition does not occur, and is one of typical random number generation. Here, the magnetic projection refers to a physical projection formed on a magnetic material or a magnetized portion. Next, the M sequence will be described.
FIG. 2 is a diagram illustrating an example in which an M sequence is applied to 7-bit data. As can be seen in FIG. 2, each 7-bit data is one bit shifted to the right with respect to the upper 7-bit data, and new 1-bit data is added from the left. By properly repeating the data to be added, it is possible to create a different numerical pattern for any 7 bits. The relationship between the pattern and the position is stored in a memory, and the absolute position can be determined by detecting data in a range corresponding to 7 bits. Such a detecting means is called a memory wheel method.

The annular yoke 6 with respect to the number of pole pairs of the inner rotor 1 so that the reduction ratio of the three magnetic gears is different from (n-1), n, (n + 1) for an arbitrary integer n of 2 or more.
The number of pole pairs of 1, 62 and 63 is set respectively. For example, if n = 31 and the number of pole pairs of the inner rotor 1: Pi = 1, the number of pole pairs of the annular yokes 61, 62, and 63 is 30, 31, and 32, respectively, according to equation (1). This is 3
It is also the reduction ratio of two magnetic gears. By setting the reduction ratio as an integer that is very close, the least common multiple can be increased. In this example, the least common multiple is 14880. Since the combination of the rotation angles of the outer rotor is equal to the least common multiple, the rotation number can be detected up to 14880 rotations. Further, since the memory wheel requires 5 bits of data from the reduction ratio (32 = 2 ⁵ ), five Hall elements 8 are specified as data detecting means on the outer periphery of the annular yokes 61, 62, 63 via an air gap. Are arranged at intervals. A permanent magnet 9 for applying a bias magnetic field is arranged on the outer periphery of the Hall element 8.

The operation of the embodiment will be described. With the rotation of the inner rotor 1, each of the annular yokes 61-63
Are rotated, and the Hall elements 8 are formed by the M-sequence pattern by the magnetic projections 64 provided on the outer periphery of each of the annular yokes 61 to 63.
, And a 5-bit signal is obtained from the combination. The rotation angles of the outer rotors 21 to 23 are obtained by referring to this signal and data stored in a ROM (not shown). From the combination of the rotation angles, the rotation angle of the inner rotor 1 is obtained using a calculator (not shown). The rotation angle of the inner rotor 1 may be stored in advance in a ROM (not shown) and the rotation angle of the inner rotor 1 corresponding to the combination of the rotation angles of the outer rotors 21 to 23 may be referred to.

It should be noted that the present invention is not limited to the above description, and that a protrusion is formed on a magnetic body without providing a magnetic pole on the outer periphery of each annular yoke, and the M
A series may be configured. Further, the magnets arranged on the outer periphery of each annular yoke may be ring-shaped or arc-shaped magnets, and it goes without saying that the magnet may be manufactured by magnetizing a magnetic material formed by sputtering.

[0012]

As described above, according to the present invention, a plurality of magnetic gears which rotate at a predetermined reduction ratio with respect to the rotation of the inner rotor are formed, and a ring-shaped magnet is formed on the outer peripheral surface of the annular yoke of the outer rotor. Are arranged, and the magnets are magnetized so as to form an M series. A plurality of magnetic detecting means are provided on the outer periphery of the outer rotor via a gap, and a memory wheel is formed on the outer periphery of each magnetic gear. The multi-rotation amount is detected from the signal of, so even if the power is cut off due to a power failure, the outer rotor will rotate if the inner rotor rotates, and the current position will be accurately known when the power is turned on again, so battery backup Are not required. Since the gears are not in contact with each other, there is no need to worry about gear noise or gear wear, and the life is extended. Even if a plurality of magnetic gears are configured, only one inner rotor is required, so that a multi-rotation encoder having features such as a simpler structure, smaller size, and the like than mechanical gears can be realized.

[Brief description of the drawings]

1A and 1B are diagrams showing a configuration of an embodiment of the present invention, wherein FIG. 1A is a longitudinal sectional view of the embodiment, and FIG. 1B is a cross-sectional view taken along a dotted line of FIG.

FIG. 2 is a diagram showing an example in which an M sequence is applied to 7-bit data.

[Explanation of symbols]

 1: inner rotor 21, 22, 23: outer rotor 3: permanent magnet 4: bearing 5: inductor 61, 62, 63: annular yoke 64: projection 71, 72, 73: bearing 8: Hall element 9: permanent magnet 10: Absolute encoder 11: Soft magnetic yoke 12: Permanent magnet

Claims (5)

[Claims] 1. A multi-rotation encoder including an absolute value encoder for detecting an absolute value angle within one rotation and a means for detecting a rotation amount, wherein a cylinder coaxially supported with the absolute value encoder. 2 around
An inner rotor in which different magnetic poles are arranged alternately, the number of poles being an integral multiple of the same, and a plurality of magnetic materials that are coaxially rotatably supported on the outer side of the inner rotor via magnetic modulation means and are rotatably supported. It has an annular yoke, and a predetermined number of different magnetic poles, each being an integral multiple of 2, are arranged on the inner periphery of each annular yoke so as to be adjacent to each other and have different polarities, and a magnet is arranged on the outer periphery of each annular yoke. An outer rotor that is magnetized such that the magnets are in the M series forms a plurality of magnetic gears in which the outer rotor rotates at a predetermined reduction ratio with respect to the rotation of the inner rotor. A plurality of magnetic detecting means are provided through an air gap, a memory wheel is configured with magnets on the outer periphery of each outer rotor, and a multi-rotation amount is detected from a signal of the memory wheel. Code. 2. A multi-rotation encoder comprising an absolute value encoder for detecting an absolute value angle within one rotation and a means for detecting an amount of rotation, wherein N, S is provided on the outer periphery of a cylinder coaxially with said absolute value encoder. Magnetic poles are alternately arranged, and an inner rotor having an integral multiple of 2 is provided. The inner rotor is rotatably supported on the outer periphery of the inner rotor coaxially with the inner rotor via magnetic modulation means. A predetermined number of magnetic poles, which is an integral multiple of 2, are arranged adjacent to each other and have different polarities on the inner periphery of the outer rotor, and the outer rotor is rotated by a predetermined distance with respect to the rotation of the inner rotor. A plurality of magnetic gears rotating at a reduction ratio of: a projection made of a magnetic material is provided on the outer periphery of the outer rotor; A plurality of magnetic detecting means are provided on the outer circumference of the rotor with a gap therebetween, and a permanent magnet is arranged on the outer circumference of the magnetic detecting means to constitute a memory wheel, and a multi-rotation amount is detected from a signal of the memory wheel. Multi-rotation encoder. 3. The multi-rotation encoder according to claim 1, wherein
A multi-rotation encoder, wherein a magnet arranged on the outer periphery of the outer rotor is a ring magnet. 4. The multi-rotation encoder according to claim 3, wherein
A multi-rotation encoder, wherein a ring magnet arranged on an outer periphery of an outer rotor is formed by sputtering. 5. The multi-rotation encoder according to claim 1, wherein
A multi-rotation encoder, wherein a magnet arranged on the outer periphery of the outer rotor is an arc-shaped magnet.