JPH02188145A - Motor provided with rotary encoder - Google Patents

Abstract

PURPOSE:To facilitate mounting/dismounting of a motor by detecting the pole position and the rotational displacement through a pair of printed boards fixed to a cup-shaped fitting section surrounding a shaft projected from the bracket of the motor, and a photo-interrupter. CONSTITUTION:A rotary shaft 4 is projected from a bracket 2 fixed to the case 1 of a motor, and a cap-shaped fitting section 11 having a cylindrical face and end faces is fixed to the bracket 2. A pair of fan-shaped printed boards 21, 31 are fixed through a gap (a) to the fitting section 11 movably in the circumferential direction. A U-shaped pole detecting photo-interrupter 22V is fixed to the motor side of the printed board 21 and faced with a disc 23 for magnetic pole fixed to the shaft 4. A U-shaped photo-interrupter 32a for detecting rotational displacement is fixed to the opposite side from the motor and facing a disc for rotational displacement fixed to the shaft 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a permanent magnet rotor type electric motor equipped with a detection device consisting of a photointerrupter and a disk for detecting magnetic pole position and rotational displacement, respectively. Regarding electric motors with rotary encoders.

[Prior Art] FIG. 3 is a sectional view showing a conventional example of an electric motor equipped with a rotary encoder. A permanent magnet rotor 5 mounted on a shaft 4 rotatably supported by a bracket 2 is provided on the inner periphery of a stator 3 attached to a frame 1. Bracket 2
A rotary encoder 7 is attached to the motor via an intermediate bracket 6, and an input shaft 8 of the rotary encoder 7 is coupled to the shaft 4 of the electric motor via a coupling 9.

Although the internal structure of the rotary encoder 7 is not particularly shown, a magnetic pole position detecting device and a rotational displacement detecting device each consisting of a photointerrupter and a disk are built into the outer jacket of the rotary encoder 7, and both the photoinclaves The controller is attached to a single disc-shaped printed circuit board.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, the electric motor, the mouth, and the encoder are assembled separately and then connected using couplings, so that the linearity of both shafts is maintained and unreasonable force is not applied to both shafts or bearings. There are operational difficulties in combining them. Moreover, not only is the coupling required as a component, but the overall length is correspondingly long.

A printed board with a magnetic pole disk and a rotational displacement disk fixed to the shaft protruding from the end of the motor without using a coupling as described above, and a photointerrupter for each of the disks attached to the outer cover side. There are various possible structures for fixing the . However, this involves some operational difficulties.

Particularly when the electric motor is a servo motor, high precision is required for the rotational displacement disk.
There are fine slits corresponding to 1,000 pulses per cycle, the thickness of the disk is, for example, 70 μm, and it is delicate and requires great care when handling manually.

An object of the present invention is to assemble both disks and both photointerrupters individually at the end of an electric motor with a protruding shaft, so that no unreasonable assembly force is applied to the disks, especially the delicate rotational displacement disks. An object of the present invention is to provide an electric motor equipped with a rotary encoder.

(Means for Solving the Problems) An electric motor with a rotary encoder of the present invention has a shaft of the motor protruding from an outer sheath of the electric motor including a rotor with a permanent magnet, and a cylindrical surface and an end surface of the electric motor are provided on the outer sheath. A pair of printed circuit boards having a sector-shaped gap that can be moved in the circumferential direction are fitted to this fitting part, and a U-shaped part is formed on the motor side of one of the printed circuit boards. A magnetic pole detection photo-interrupter is attached so as to face each other so as to surround the outer periphery of the magnetic pole disk fixed to the shaft, and a U-shaped rotational displacement detection photo-interrupter is attached to the side opposite to the motor side of the other printed circuit board. These disks are arranged to face each other so as to surround the outer periphery of a rotary displacement disk fixed to a shaft.

[Effect]

When disassembling, remove the cover and attach the rotational displacement detection photointerrupter with one printed circuit board with the magnetic pole detection photointerrupter attached to the mating part and the rotational displacement disk fixed to the shaft. Remove the other attached printed circuit board from the fitting part. At this time, if the depth of the fitting part is approximately the same as or shallower than the axially outer gap between the disk and the U-shaped photointerrupter, the other printed circuit board can be moved axially from the fitting part. By pulling it out a little, only the other printed circuit board can be moved in the radial direction from the position where it contacts the outer end of the fitting part.

This radial movement eliminates radial dimensional interference between the rotational displacement detection photointerrupter and the disk.

Therefore, in this state, the thin and delicate rotary displacement disk can be removed straight in the axial direction by removing the screw, and no excessive external force is applied. Preferably, then the depth of the fitting portion may be only slightly deeper than the axial outer gap.

Here, if we assume that the pair of printed circuit boards are made of a single piece as in the past, the magnetic pole detection photointerrupter will also move with the movement in the radial direction, and the U-shaped The printed circuit board can only be moved in the radial direction up to the limit where the magnetic pole disk hits the radial odor area.

However, in general, regarding the radial dimensional relationship between the disk and the interrupter, the outer circumference of the disk and the photo The radial gap to the back of the interrupter is quite small, so at the limit position of the radial movement determined by this gap, the outer periphery of the disk still partially interferes with the incrementer. In order to pull out the rotary displacement disk in the axial direction in this interference state, the disk that is fitted to the shaft with no gap at its inner diameter must be tilted slightly, or when pulled out straight, it must be bent at the interference part. I have to pull it out. At this time, the thin disk may be deformed at the fitting part with the shaft or at the interference part on the outer periphery, or fingerprints or the like may adhere to the slit, which may cause malfunction of rotational displacement detection, making the work delicate.

Returning to the original, when the printed circuit boards are separated as a pair, there is no limit to the movement in the radial direction, and the other printed circuit board can be moved in the radial direction to a position where there is no interference. After that, if you pull out the rotational displacement disk straight, no unreasonable external force will be applied. After that, remove the spacer tube and pull out the magnetic pole disk along with the pair of printed circuit boards from the shaft. This magnetic pole disk is generally thick, and even if it is hooked onto a magnetic pole detection photointerrupter and pulled out, it does not have the same problems as thin and delicate rotary displacement disks. Therefore, place the magnetic pole disk on the motor side.

During assembly, the procedure is reversed to that during disassembly, and the situation is approximately the same.

〔Example〕

FIG. 1 is a cross-sectional view showing an embodiment of an electric motor with a rotary encoder, showing the 1-1 cross section in FIG. 2, and FIG. 2 is a cross-sectional view taken along Illustrations of parts are omitted.

In these drawings, parts with the same reference numerals as those in the conventional example have approximately the same functions.In other words, on the inner periphery of the stator 3 attached to the frame l, there is a shaft 4 that is rotatably supported on the bracket 2. A permanent magnet type rotor 5 is provided.

As a characteristic structure of the embodiment, the shaft 4 protrudes from the bracket 2 that constitutes a part of the outer cover of the electric motor, and the bracket 2 is formed with a fitting part 11 consisting of a cylindrical surface and an end surface. . This fitting part 11 has a pair of printed circuit boards 21 and 3 which are fan-shaped and have a gap a that allows mutual movement in the circumferential direction.
1 are fitted together at their outer peripheries as mutually divided substrates. The - side printed circuit board 21 is equipped with a peripheral circuit for magnetic pole detection, and a U-shaped magnetic pole detection photointerrupter 2 is mounted on the motor side.
2u, 22v and 23- are fixed with screws corresponding to the USV and W phases. The printed circuit board 21 is fixed with the elongated hole 21a and the screw so that the magnetic pole detection photointerrupter can be adjusted to match the circumferential position of the permanent magnet of the rotor 5.

The other printed circuit board 31 is equipped with a peripheral circuit for detecting rotational displacement, and U-shaped rotational displacement detection photointerrupters 32a and 322 are screwed on the side opposite to the motor side, that is, on the outside, corresponding to the AB phase and Z phase. Fixed.

A magnetic pole disk 23 is fixed at the position on the motor side of the printed circuit board 21.31 with its inner periphery fitted to the shaft 4 without any gaps, and its outer periphery is fixed to the magnetic pole detection photointerrupter 22u.
, 22v and 22- are surrounded by U-shaped portions and face each other. At a position on the opposite side of the printed circuit board from the electric motor side, a rotational displacement disk 33 is fixed in its axial position by a spacer tube 41b, and is fitted onto the shaft 4 without any gap at its inner periphery.
Its outer periphery includes the rotational displacement detection photointerrupter 32a,
The opposing disks 23.33 surrounded by the U-shaped portions 32z are connected to the shaft 4 by the spacing tubes 41a, 41b and 4.
The axial position is determined by 1c, and it is fixed to the shaft 4 with a screw 43 through a washer 42. The detection part is a cover 44
protected by

The approximate dimensions of both disks 23 and 33 are illustrated.

If the electric motor has, for example, six poles, the magnetic pole disk 23 is
Three fan-shaped parts are provided on the outer periphery, and cutouts (slits may also be provided) opening on the outer periphery between the fan-shaped parts are provided at 60 degrees each, and the thickness thereof is, for example, 0.8 tsuru. Manufactured by punching together with the inner circumference from stainless steel. On the other hand, the rotational displacement disk 33 has, for example, 1,000 mm near the outer periphery.
The slits are precisely equally spaced, and the thickness is, for example, 70 μm, and the slits are formed from stainless steel by a photoresist method. For example, the slit width at a pitch circle of 40 is approximately 63 μm, and the slit pitch is approximately It will be 126μ steel.

Next, the outline of the mutual dimensions between the outer peripheries of both disks and the photointerrupter will be illustrated. 0.8m thick magnetic pole disk 23
is placed at the middle position of the U-shaped axial clearance of the photointerrupter, and the outer periphery of the disk has a clearance of 2.5 in the radial direction of the photointerrupter, and a radial clearance of 4.5fi. Having an interference dimension C, the light beam of the photointerrupter is cut at this interference portion.

On the other hand, the rotational displacement disk 33 having a thickness of 70 .mu.m is arranged at an intermediate position of the axial clearance of the photointerrupter of 1.8 mm, the radial clearance d on the outer periphery is 2 fi, and the interference dimension e is 4.5 mm.

The above mutual dimensions are just an example, but generally speaking, the radial clearance (d) between the disk and the photointerrupter at the outer periphery of the disk is much smaller than the interference dimension C or e.Therefore, if a pair of printed circuit boards If it is in the shape of a single disk, it will still rotate at the limit dimension (determined by the radial gap or d) that allows the disk to be moved in the radial direction after the printed circuit board is pulled out a little in the axial direction from the fitting part 11. An interference dimension C or e of the displacement disk will exist. If you try to pull out the disk in the axial direction from this state, the rotational displacement disk 33 will receive an unreasonable force from the shaft 4 or the rotational displacement detection photointerrupters 32a and 32z and deform, resulting in the rotation of the disk with a thin and minute slit. Displacement detection accuracy may deteriorate, resulting in defective products.

For example, in a six-pole electric motor, the notch on the outer periphery of the magnetic pole disk is 60'' as described above, whereas U,
The pitch of each of the three photointerrupters V and W is 40″
, a total of 80'', using the 60@ notch
The interfering part of the 0@ photointerrupter cannot be removed in the axial direction.

This is one condition that must be resolved.

The procedure for assembling or disassembling parts having the structure of the above-described embodiments has been described in the [Operations] section above.

Note that if the dimension in which the fitting portion of the shaft 4 protrudes from the disk 33 is reduced, the rotational displacement detection photointerrupter 3 can be fixed while the pair of printed circuit boards 21 and 31 are fixed to the fitting portion 11.
Axial clearance between 2a, 32z and the disk 33 (in the above example dimensions, one side is (1,8fi-Q, Q7) /
2 = 0.865, and there is some deviation), the disk should come out straight in the axial direction without hitting the photointerrupter. However, even excluding the chamfering, the protruding dimension is much larger than the axial clearance on one side, and the clearance between the inner circumference of the disc 33 and the shaft is small due to detection accuracy, so such work is unreasonable and the disc is deformed.

〔Effect of the invention〕

An electric motor with a rotary encoder according to the present invention includes a motor having a rotor with a permanent magnet, the shaft of the motor protruding from the outer sheath, a fitting portion consisting of a cylindrical surface and an end surface formed in the outer sheath, and the shaft of the electric motor having a rotor with a permanent magnet. A pair of printed circuit boards having a sector-shaped gap that can be moved in the circumferential direction are fitted to the fitting portion, and a U-shaped magnetic pole detection photointerrupter is attached to the motor side of one of the printed circuit boards, and the shaft A U-shaped rotational displacement detection photo-interrupter is attached to the side opposite to the motor side of the other printed circuit board so as to surround the outer periphery of the magnetic pole disk fixed to the shaft. Since they are arranged to face each other so as to surround the outer periphery, the overall length can be shortened without the need for parts such as couplings.

In particular, since the printed circuit board is divided into a pair of printed circuit boards, when moving the printed circuit board on the rotational displacement detection side in the radial direction prior to disassembling and assembling the rotational displacement disk, the printed circuit board on the magnetic pole detection side must be remains fixed, and the magnetic pole disk does not radially hit the magnetic pole detection photointerrupter attached here, and the printed circuit board on the rotational displacement detection side, that is, the rotational displacement detection photointerrupter attached here Can move widely in the radial direction.

Therefore, the rotational displacement disk can be pulled out straight in the axial direction and fitted, and there is no deformation due to excessive external force or the attachment of fingerprints, and optical deformation of the rotational displacement disk or its slit, which is a precision component, is prevented. This has the advantage of being able to maintain detection accuracy and also allows for automatic assembly.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the embodiment, FIG. 2 is a cross-sectional view taken along the line -■ in FIG. 1, and FIG. 3 is a cross-sectional view of the conventional example. 2... Bracket, 4... Shaft, 7... Rotary encoder, 9... Coupling, 11... Fitting part,
21゜31...Printed circuit board, 22u, 22v, 22
-...Magnetic pole detection photointerrupter, 23...Magnetic pole disk, 32a, 32z...Rotational displacement detection photointerrupter, 33...Rotational displacement disk.

Claims (1)

[Claims] 1) The shaft of the motor is made to protrude from the outer sheath of a motor equipped with a rotor equipped with a permanent magnet, a fitting portion consisting of a cylindrical surface and an end surface is formed in the outer sheath, and a fan-shaped and mutually interlocking portion is formed in the fitting portion. A pair of printed circuit boards with a gap that can be moved in the circumferential direction are fitted together, and a U-shaped magnetic pole detection photo-interrupter is attached to the motor side of one of the printed circuit boards, and the outer periphery of the magnetic pole disk is fixed to the shaft. A U-shaped rotational displacement detection photo-interrupter is attached to the side opposite to the electric motor side of the other printed circuit board, and the two printed circuit boards are arranged to face each other so as to surround the outer periphery of the rotational displacement disk fixed to the shaft. An electric motor with a rotary encoder featuring: