JP3274806B2 - Mounting structure of magnetic drum - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic drum mounting structure for a motor encoder, and more particularly to a magnetic drum mounting structure that can be mounted on a motor rotating shaft without causing stress distortion. .

[0002]

2. Description of the Related Art Some motors perform an encoder signal for detecting rotation on an outer peripheral surface of an annular magnetic drum.
In order to accurately magnetize the magnetic drum, it is necessary to mount the magnetic drum without causing stress distortion on the magnetic drum when mounting the magnetic drum on a drum holder fixed to the outer periphery of the motor rotation shaft.

FIG. 5 shows a conventional example of an encoder provided with such a magnetic drum.
It is described in Japanese Patent Publication No. In FIG. 5, a mounting portion for fixing a magnetic drum 23 having a magnetized surface 21 to be magnetized is provided at a center 24 of a bottom portion of the bowl shape.
Each of the mounting holes 25 is configured to be screwed with a screw 27 to a screwing portion 26 provided at the tip of the rotating shaft 28.

In such a magnetic drum 23, a predetermined magnetic substance powder is mixed into a resin such as PPS and stirred, and the magnetic resin is filled from a gate provided at the center of the bottom surface of the magnetic drum. The gate and the weld are formed by cutting the gate and the weld after the escape to the provided weld relief (not shown). A magnetic drum 23 formed by the above-described molding method and screwing and fixing the center 24 of the bottom surface of the magnetic drum to the tip of a rotating shaft 28 with a screw 27
Then, the occurrence of stress strain on the magnetized surface of the magnetic drum during mounting is relatively small.

[0005]

However, in order to reduce the weight of the rotating shaft or to insert a lead wire or the like into the rotating shaft, a motor formed with a hollow rotating shaft having a hollow rotating shaft has been conventionally used. It is not possible to take a mechanism of screwing and fixing the end of the rotating shaft with a screw as in the above. In addition, since the magnetic drum is formed of a resin containing a magnetic material, stress distortion may occur when the magnetic drum is attached by screws or the like, and the magnetic drum may be deformed. Even if an outer peripheral race is performed to correct this deformation, if it is subsequently used in a high-temperature environment, the stress will be removed and it will be deformed again. If the magnetic drum is deformed, the distance from the sensor fluctuates, and an appropriate encoder signal cannot be obtained.

[0006]

According to a first aspect of the present invention, there is provided a magnetic drum mounting structure having a rotating shaft and a plurality of magnetized surfaces provided with a plurality of magnetized surfaces to rotate integrally with the rotating shaft. A magnetic drum, comprising: a magnetic drum, the magnetic drum has a bottom portion having a hollow hole through which the rotating shaft is formed, and a plurality of mounting portions protruding from the bottom portion; A drum holder is fitted and fixed to an outer periphery of the rotating shaft, and a plurality of mounting portions of the magnetic drum are mounted so as to contact the drum holder.

According to a second aspect of the present invention, in the magnetic drum mounting structure, the drum holder has a mounting surface that is horizontal with respect to the axial direction of the rotating shaft, and three mounting portions for the magnetic drum are provided. The three mounting portions are in contact with the mounting surface.

An object of the present invention is to provide an encoder structure which reduces stress and strain on a magnetic drum, improves quality, and is easy to use with respect to a hollow rotary shaft by a mounting structure according to the present invention.

[0009]

FIG. 1 is a sectional view of an embodiment showing a mounting structure of a magnetic drum of an encoder for detecting rotation in combination with a motor according to the present invention.

In FIG. 1, a rotor 1 of a motor includes a hollow rotary shaft 5 supported by bearings 3 and 4 for receiving a radial direction, an annular magnet 6 fixed to the rotary shaft 5 to form a field pole, and the like. Be composed. The stator of the motor includes a yoke 8 around which a coil 7 is wound around the magnet 6 with a small gap, a body-shaped casing 9 for holding the yoke 8, and the like. An encoder E for detecting the rotation of the rotor according to the present invention is attached to the outside of the casing 9 and upward in the drawing.

A magnetic drum 10 constituting an encoder E for detecting rotation in combination with a motor according to the present invention.
Are engaged with the outer peripheral edge of the drum holder 11. The drum holder 11 is a coin-shaped member made of a non-magnetic material such as an aluminum alloy, and has a bore 20 through which a rotating shaft is formed, and is fixed to the rotating shaft 5 by shrink fitting or the like.
In addition, it has a mounting surface that is horizontal with respect to the axial direction of the rotating shaft. The magnetic drum 10 fitted to the outer peripheral edge of the drum holder 11 is provided with a plurality of attachment portions, which will be described later, protruding from the bottom portion 12 at the outer edge of the bottom portion 12 that comes into contact with the drum holder 11. And the drum holder 11
A magnetic drum 10 is coated and engaged on the outside, and a plurality of mounting portions of the magnetic drum are provided so as to abut against the drum holder 11, and the magnetic drum 10 is screwed through a through hole opened in the mounting portion. 15 is screwed to the drum holder 11.

The screwing in this mounting structure minimizes distortion on the magnetized surface of the magnetic drum 10 when screwed with equal pressure at three places, and substantially eliminates the influence on the magnetized surface. can do. That is, the mounting part is the bottom part 1
Since only three mounting portions are in contact with the mounting surface, the tightening pressure of the screw 15 is hardly exerted on the magnetized surface via the bottom surface portion 12.

When a predetermined voltage is applied to the terminal 16 of the motor having the above-described structure, power is supplied to the coil 7, and the rotor 1 is arranged in an annular shape by electromagnetic interaction with the magnet 6.
Rotates. At the same time, the drum holder 11 rotates, and the magnetic drum 10 also rotates. Now, the magnetic drum 10
When the magnetic sensor 17 is disposed at a slight distance from the outer peripheral surface, the magnetic sensor 17 detects a signal corresponding to the rotation of the rotor.

FIG. 2 is a view of one embodiment showing the structure of a magnetic drum according to the present invention. FIG. 2A is a view showing the molding method, and FIG. 2B is a top plan view and a side view thereof.

In FIG. 2A, the magnetic drum is a PPS.
A predetermined magnetic substance powder is mixed with resin and the like, and the mixture is agitated. The magnetic resin is press-fitted from a gate 18 provided at the center of the bottom of the magnetic drum 10, and is released from a lower portion of the magnetized surface 21 in the drawing to a weld relief 19. After that, it is formed by cutting the gate 18 and the weld relief 19. At this time, the flow of the resin injected from the gate 18 may cause a weld line to be generated by the through hole 14, but this is prevented from being generated by the escape to the weld escape 19 provided on the outer periphery of the magnetic drum 10. be able to.

In FIG. 2B, the magnetic drum 10 has a bottom surface portion 12 in which a hole 20 through which a rotating shaft passes is formed. , A plurality of projecting attachment portions 13 are provided. As described above, the drum holder having the surface to be mounted that is horizontal with respect to the axial direction of the rotating shaft is fitted and fixed to the outer periphery of the rotating shaft. The mounting portions 13 come into contact with each other.

Each mounting portion 13 has a through hole 14 at the center thereof, through which a screw can be inserted. The screw 15 uses only the mounting portion 13 in the pressing direction, for example, a pan-head screw, and does not use a flathead screw that also presses the magnetized surface 21 in the pressing direction. Therefore,
The magnetic drum 10 does not use the screw 15 to set the magnetized surface 21 in the pressing direction.
No stress-strain occurs in No. 1. Then, it is screwed into a screw hole provided in the drum holder and attached.

FIG. 3 is a side view and a plan view of another embodiment showing the structure of the magnetic drum according to the present invention, which is contrasted with FIG. Members having the same functions as those in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

In FIG. 3, the resin portion 22 connected to the magnetized surface 21-1 has an H-shaped cross section, and as shown in FIG.
Three mounting portions 13 protruding from the bottom surface portion 12 of the magnetic drum 10 so as to abut on the drum holder are provided. With such a structure, a magnetic medium for magnetic pole detection (not shown) can be attached to the space A in the drawing, and the drum holder described above can be attached to the space B in the drawing. The size can be reduced.

FIG. 4 is a side view and a plan view of another embodiment showing the structure of the magnetic drum according to the present invention, which is contrasted with FIG. Members having the same functions as those in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

In FIG. 4, the bottom 1 of the magnetic drum 10 is shown.
The three mounting portions 13 protruding from 2 are located near the magnetized surface 21-2, and the mounting portions 13 protrude in both up and down directions. As a result, the mounting direction of the magnetic drum 10 can be eliminated.

[0022]

According to the present invention, not only can the rotary shaft be used for an encoder having a hollow rotary shaft, but also the magnetic drum is formed of a magnetic material-containing resin. Since the mounting portion protrudes from the vicinity of the magnetized surface and engages with the outer peripheral edge of the drum holder via the mounting portion, when the magnetic drum is mounted on the drum holder with screws or the like, almost no stress distortion occurs. be able to. As a result, stress distortion on the magnetized surface is reduced, and the distance between the magnetized surface and the magnetic sensor does not change, so that an appropriate encoder signal can be obtained. In addition, the magnetic drum
Since it is resistant to environmental changes, it is possible to provide an encoder structure with improved quality and easy use.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment showing a mounting structure of a magnetic drum of an encoder that performs rotation detection and the like in combination with a motor according to the present invention.

FIG. 2 is a view of an embodiment showing a structure of a magnetic drum according to the present invention.

FIG. 3 is a view of another embodiment showing a structure of a magnetic drum according to the present invention.

FIG. 4 is a view of another embodiment showing the structure of the magnetic drum according to the present invention.

FIG. 5 is a conventional example of an encoder provided with a magnetic drum.

[Explanation of symbols]

 Reference Signs 5 Rotating shaft 10 Magnetic drum 11 Drum holder 12 Bottom part 13 Mounting part 14 Through hole 21 Magnetized surface E Encoder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01D 5/00-5/62 G01B 7/00-7/34 G01B 11/00-11/30 G01P 1 / 00-3/80

Claims (2)

(57) [Claims] A magnetic drum having a rotating shaft and a plurality of magnetized surfaces and rotating integrally with the rotating shaft;
In the magnetic drum mounting structure, the magnetic drum has a bottom portion formed with a hollow hole through which the rotating shaft is formed, and a plurality of mounting portions protruding from the bottom portion. Is a mounting structure for a magnetic drum, wherein a drum holder is fitted and fixed, and a plurality of mounting portions of the magnetic drum are mounted so as to contact the drum holder. 2. The drum holder has a surface to be mounted that is horizontal with respect to the axial direction of the rotating shaft, and three mounting portions for the magnetic drum are provided, and the three mounting portions are mounted on the magnetic drum. 2. The magnetic drum mounting structure according to claim 1, wherein the magnetic drum is in contact with the surface.