JPH0150310B2 - - Google Patents

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention has a rotor that rotates around a stator, and the rotor rotates two members, an inner member and an outer member, which have different coefficients of thermal expansion. The present invention relates to an outer rotary electric motor configured to be stacked in a radial direction, and particularly to a structure for mutual attachment of two members constituting the rotor.

(b) Background of the Technology This type of external rotary electric motor is sometimes used to rotate a disk, such as a magnetic disk, which requires rotational precision. Such a disc expands or contracts due to changes in environmental temperature or the heat generated by the motor itself, so it must be installed on the motor to prevent eccentricity, deformation, vibration, etc. from occurring during rotation due to this expansion and contraction action. There is a need. Therefore,
This type of external rotating electric motor has a structure in which the rotor to which the disc is attached is capable of reliably preventing eccentricity, deformation, vibration, etc. of the disc due to expansion and contraction of the disc due to temperature changes. It is requested that

(c) Prior Art and Problems FIG. 1 is a diagram showing a first prior art example, and is a diagram showing an example in which a conventional outside rotary electric motor is used in a magnetic disk device. In the figure, reference numeral 11 indicates the main body of the device, 12 indicates the boss portion of the main body 11, and 13 indicates the boss portion 12.
A stator (stator) attached to the outer periphery of 14
16 is a rotating shaft that is rotatably supported in the boss portion 12 via a bearing 15, and 16 is a rotating hub that is fitted and fixed to the upper end of the rotating shaft 14 by a method such as shrink fitting, and is rotatable together with the rotating shaft 14. , 17 is a rotor adhesively fixed to the inside of a hollow cylindrical portion 16b formed integrally with the end wall 16a of the rotating bub 16, 18 is a rotor composed of the rotating hub 16 and the rotor 17, and 19 is the rotating hub 16. A plurality of magnetic disks (discs) inserted into the outside of the cylindrical portion 16b and arranged in multiple stages with a ring-shaped spacer 20 interposed therebetween, 2
Reference numeral 1 indicates a disc-shaped clamp for fixing the magnetic disk 19 under salt pressure, and 22 indicates a fastening screw for fastening the disc-shaped clamp 20. In this case, a rotor 18 is composed of a rotating hub (outer member) 16 and a rotor (inner member) 17.
Although not shown in detail, the stator 13 is composed of a stator core and stator windings. The rotating hub 16 is made of aluminum (Al) or an Al alloy in this case, and the magnetic disk 19 is also made of Al or an Al alloy.
They are formed from an Al alloy substrate, and both have substantially similar coefficients of thermal expansion. Incidentally, the ring-shaped spacer 20 also has substantially the same coefficient of thermal expansion as both the above-mentioned 16 and 19. The rotor 17 includes a cylindrical iron housing 17a and a permanent magnet 17b fixed to the inside of the housing 17a.
It is composed of. The upper portion of the outer periphery of the cylindrical housing 17a of the rotor 17 is adhesively fixed to the inner periphery of the cylindrical portion 16b of the rotating hub along the circumferential direction. Therefore, in this case, the coefficient of thermal expansion of the rotating hub 16 as the outer member is larger (approximately twice) than that of the rotor 17 as the inner member.
It is. The electric motor of this first conventional example includes a stator 13 formed in this manner and a rotor 18 that rotates around the stator 13. The magnetic disk 19 is formed into a donut-shaped disk, and as described above, the magnetic disk 19 is attached to the cylindrical portion 16 of the rotating hub 16.
It is inserted on the outer periphery of b. The inner diameter of the magnetic disk 19 is set to be slightly larger (for example, about 20 to 30 μm) than the outer diameter of the cylindrical portion 16b. Therefore, there is a slight gap (clearance) between the inner circumferential end surface of the magnetic disk 19 and the outer circumferential surface of the cylindrical portion 16b. Now, with this first conventional example, there is almost no problem when the environmental temperature changes to the high temperature side (e.g. 80℃), but when it changes to the low temperature side (e.g. -40℃)
In this case, the amount of contraction of the rotary hub 16 is greater than the amount of contraction of the housing 17a, so relatively speaking, the contraction action of the cylindrical portion 16b is partially blocked by the housing 17a. Then, the magnetic disk 19 also contracts in the same way as the cylindrical portion 16b, but since the contraction action of the cylindrical portion 16b is blocked midway as described above, the contraction action of the magnetic disk 19 is now caused by the cylindrical portion 16b. It will be stopped on the way. As a result, there is no clearance between the inner circumferential end surface of the magnetic disk 19 and the outer circumferential surface of the cylindrical portion 16b. in this case,
The magnetic disk 19 is rarely inserted into the cylindrical portion 16b with uniform clearances along the circumferential direction, but in most cases it is inserted with uneven clearances. Therefore, when the magnetic disk 19 contracts, the inner peripheral end surface portion with a smaller clearance first contacts the outer peripheral surface of the cylindrical portion 16b, and then the inner peripheral end surface portion with a larger clearance contacts the outer peripheral surface of the cylindrical portion 16b. become. For this reason, the magnetic disk 19 has its center of rotation shifted toward the inner circumferential end surface where the clearance is smaller with respect to the center of rotation of the rotating hub 16, resulting in eccentricity. Due to this eccentricity, the center of rotation and the center of gravity of the magnetic disk 19 are shifted, and when the magnetic disk 19 is rotated at high speed (for example, 3600 rpm), there is a problem in that undesirable phenomena such as vibration are likely to occur. Further, since the magnetic disk 19 is prevented from contracting midway through, there is a problem in that deformation such as waviness in the horizontal direction is likely to occur. This waviness deformation has undesirable effects on the magnetic head for writing and reading information on the magnetic disk 19.

FIG. 2 is an explanatory diagram of a second conventional example devised to solve the above-mentioned problem, and is similar to that of FIG.
FIG. 7 is a diagram showing the main parts of the second conventional example, corresponding to a cross section taken along the line AA'. In this second conventional example, the bonded portion between the cylindrical portion 16b and the housing 17a is not provided all around the circumference as in the first conventional example, but is provided at three partial bonded portions 16c, 16d, A clearance S is provided except for 16e. By providing the clearance S in this way, this second conventional example allows the cylindrical portion 16 to
The contraction action of b causes the partial bonding parts 16c, 16d, 16
Since the portion of the cylindrical portion 16b provided with the clearance S can be almost freely contracted only by being blocked by the point e, the problems in the first conventional example described above can be largely solved. However, in this second conventional example, when the environmental temperature is high, the cylindrical portion 16
The expansion action of b causes the partial adhesive parts 16c, 16d, 16
e, and the clearance S section can expand almost freely, so that the overall planar cross-sectional shape does not expand into a perfect circle, but in extreme terms, deforms and expands into a triangular shape. Therefore, the magnetic disk 19
becomes susceptible to deformation due to the force of partially pushing the inside part apart. In particular, the lowermost magnetic disk 19 (see FIG. 1) is easily deformed by the deformation and expansion of the cylindrical portion 16b because the lower surface of its inner side is in contact with the flange portion 16f of the cylindrical portion 16b. There is a problem. Incidentally, such a cylindrical portion 16
It is conceivable to make the inner diameter of the magnetic disk 19 sufficiently large so that it has a large clearance with the outer peripheral surface of the cylindrical portion 16b so as not to be affected by the deformation expansion and contraction of the magnetic disk 16b. If it is made too large, it becomes very difficult to center the magnetic disk 19 with respect to the rotating hub 16.
In practice, this is not possible.

As described above, in the conventional example, two members, the rotating hub (outer member) 16 and the rotor (inner member) 17, which have different coefficients of thermal expansion, are rotated by gluing their radially inner and outer circumferential surfaces. Because of the structure of the child 18, the above-mentioned problems are likely to occur when the environmental temperature changes to either a high or a low temperature side.

(iv) Purpose of the Invention In view of the above-mentioned problems of the prior art, the purpose of the present invention is to prevent the two members, the inner member and the outer member, having different coefficients of thermal expansion, even if the environmental temperature changes to either the high or low temperature side. It is possible to prevent deformation expansion and deformation contraction, especially of the outer member of the constructed rotor,
It is an object of the present invention to provide an outside rotary electric motor that does not adversely affect rotating members such as disks attached to a rotor.

(E) Structure of the invention In order to achieve the above object, the present invention has a rotor that rotates around a stator,
In an outer rotary electric motor in which the rotor is constructed by laminating two members, an inner member and an outer member having different coefficients of thermal expansion in the radial direction, the two members having different coefficients of thermal expansion are laminated in the circumferential direction. There is provided an outer rotary electric motor characterized in that the motors are separated from each other along the length through a gap and are fixed only between their mutual ends.

(f) Embodiments of the invention Examples of the invention will be described in detail below with reference to the drawings.

3 to 5 are diagrams for explaining embodiments of the present invention. In these figures, the same or equivalent parts as in the above-mentioned Figs. 1 and 2 are designated by the same reference numerals. Therefore, numeral 11 is the main body of the device, 12 is the boss portion of the main body 11, 13 is the stator (stator: inner member), 14 is the rotating shaft, 15 is the bearing, 16' is the rotating hub according to the present invention, and 17 is the rotor. , 18' is a rotor according to the present invention composed of a rotating hub (outer member) 16' and a rotor (inner member) 17, 19 is a magnetic disk, 20 is a ring-shaped spacer, 21 is a disk-shaped clamp, 22 indicate fastening screws. And rotating hub 1
6' and rotor 18', the description thereof will be omitted.

FIG. 3 shows an example in which the outer rotary electric motor of the present invention is used in a magnetic disk device.
0 is a diagram showing the appearance of 0. The external rotary electric motor of the present invention is housed inside the main body 11 of the device. In addition, the code|symbol 11a has shown the canopy of the main body 11.

FIG. 4 is a sectional view taken along the line B-B' in FIG. 3, and is a diagram schematically showing the inside of the magnetic disk device 10. As shown in FIG. Reference numeral 25 indicates a head positioner, and 26 indicates a magnetic head supported by the head positioner 25 via a support member 27. A plurality of magnetic heads 26 are arranged to face the plate surface of the magnetic disk 19, respectively. The head positioner 25 is formed to be able to move forward and backward in the direction of arrow C. The outer rotary electric motor of the present invention is installed inside the ring-shaped spacer 20 in order to rotate the magnetic disk 19.

FIG. 5 is a half-sectional view of the main part according to the present invention in FIG. 4, and corresponds to the above-mentioned FIG. 1 (conventional example). The rotating hub 16' is made of Al or Al alloy, as in the case of the conventional example described above, and is composed of an end wall part 16'a and a hollow cylindrical part 16'b formed integrally with the end wall part 16'a. has been done. Also,
The rotating hub 16' is fitted and fixed to the upper end of the rotating shaft 14 by a method such as shrink fitting, and is arranged to be rotatable together with the rotating shaft 14. A ring-shaped projection 16'c is formed on the inner surface of the end wall portion 16'a, protruding in the axial direction and continuous in the circumferential direction. The end of the rotor 17 is welded and fixed to the tip of this ring-shaped projection 16'c. The rotor 17 is arranged such that the outer circumferential surface in the radial direction of the cylindrical housing 17a and the inner circumferential surface of the rotating hub cylindrical portion 16'b are spaced apart from each other with a gap of size W over the entire circumferential direction. It is set up. Ring-shaped protrusion 1
6'c and the end of the rotor 17, the cross-sectional shape of the tip of the protrusion 16'c is as shown in FIG.
The radial outer peripheral surface of the stepped portion is bonded to the inner end surface of the cylindrical housing 17a of the rotor 17, and at the same time, the stepped end surface of the protrusion 16'c is permanently attached to the housing 17a of the rotor 17. magnet 1
They are configured by being adhered to the end faces of 7b, respectively. The value of the gap W may be very small, but as a guide, it is sufficient to set it slightly larger than (difference in coefficient of thermal expansion between the rotating hub 16' and the cylindrical housing 17a) x amount of environmental temperature change (°C)). Of course, the set value of this gap W is set when the environmental temperature is normal temperature (for example, about 20° C.). In this way, the outer rotary type electric motor of this embodiment is configured to include the stator 13 and the rotor 18' formed as described above.

Now, in this embodiment configured as described above, when the environmental temperature changes to a low temperature side (for example, -40°C), the amount of contraction of the cylindrical portion 16'b, which is larger than the amount of contraction of the housing 17a, is reduced to the gap W. It is absorbed by the
The cylindrical portion 16'b can freely and evenly contract without being blocked by the housing 17a. Therefore, the cylindrical portion 16'b is prevented from deforming and contracting, and the magnetic disk 19 will not be adversely affected by eccentricity, deformation, or the like. That is, in this case, the end wall portion 16'a of the rotating hub 16 also contracts, but most of the displacement with respect to the rotor 17 is absorbed by the projection 16'c.
The contraction effect of the cylindrical portion 16b is not adversely affected. This time, the environment temperature is on the high temperature side (for example, 80
℃), for the same reason as in the case of the low temperature side, the cylindrical portion 16b becomes free without being inhibited from expanding, deformation and expansion are prevented, and eccentricity, deformation, etc. with respect to the magnetic disk 19 are prevented. There will be no negative impact.

In the case of the above embodiment, the ring-shaped projections 16'c are formed continuously in the circumferential direction, but even if they are formed intermittently in the circumferential direction, the same effect as in the above embodiment can be obtained. can be obtained. In addition, ring-shaped protrusion 1
The end face of the rotor 17 is connected to the rotating hub 1 without providing 6'c.
Even if it is directly adhesively fixed to the inner surface of the end wall 16'a of 6', substantially the same effect as in the above embodiment can be obtained.

(g) Effects of the Invention As explained above in detail, the outer rotary electric motor of the present invention has two members having different coefficients of thermal expansion, the inner member and the outer member constituting the rotor, in the circumferential direction. By forming a structure in which the outer members are separated from each other through gaps and are fixed only between their mutual ends, the outer member can freely expand and contract without being inhibited. It is possible to prevent deformation expansion and deformation contraction of the outer member, and as a result, it is possible to prevent adverse effects such as eccentricity and deformation on the rotating body (for example, a disk) attached to the outer member,
It has the great effect of increasing the rotation precision of the rotating body, and contributes to improved product performance and reliability.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first conventional example, which shows an example in which a conventional outside rotary electric motor is used in a magnetic disk device, and FIG. 2 is an explanatory diagram of a second conventional example.
FIG. 3 is a diagram showing the main parts of the second conventional example corresponding to the cross section taken along the line A'. FIG. 4 is a cross-sectional view taken along the line B-B' in FIG. 3, schematically showing the inside of the magnetic disk device 10, and FIG. 5 is a half-sectional view of the main parts of the present invention in FIG. 4. DESCRIPTION OF SYMBOLS 10...Magnetic disk device, 11...Device main body, 12...Boss portion of main body 11, 13...Stator (stator), 16'...Rotating hub, 16'a...
End wall, 16'b...Hollow cylindrical part, 16'c...Ring-shaped projection (protrusion-like adhesive part), 17...Rotor, 1
7a...Cylindrical housing, 17b...Permanent magnet, 18'...Rotor composed of rotating hub (outer member) 16' and rotor 17, 19...Magnetic disk (disk).

Claims (1)

[Claims] 1. An outer body having a rotor that rotates around a stator, the rotor being constructed by laminating two members, an inner member and an outer member, having different coefficients of thermal expansion in the radial direction. In the rotary electric motor, the two members having different coefficients of thermal expansion are separated from each other via a gap along the circumferential direction, and are fixed only between their mutual ends. Rotary electric motor. 2. The outer rotary electric motor according to claim 1, wherein the end of the inner member of the two members is adhesively fixed to a protruding adhesive portion provided in advance inside the end wall of the outer member.