JPH0213256A - Motor - Google Patents

Abstract

PURPOSE:To absorb rattling or vibration of a rotor shaft by fixing a magnet at a position of a stator facing with a rotor such that the rotor shaft is pushed unilaterally in the radial direction of the bearing for the stator. CONSTITUTION:A cored spindle motor 1 for a disc drive comprises a rotor 2 and a stator 3 which supports the rotor 2 rotatably. The rotor 2 comprises an approximately disc type rotor yoke 4, a shaft(spindle) 7, a chuck yoke(turn table) 8, an annular rotor magnet having large diameter secured to the outer circumference of the upper face of the rotor yoke 4, etc. The stator 3 comprises a disc stator yoke 9, a cylindrical housing 11 provided with a disc flange section 11a, a bearing 13, multi-phase driving coils 14, a pair of disc cores 15, 16 secured to the flange section 11a and a magnet 17. By such arrangement, rattling in the thrust direction can be absorbed reliably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor used in a disk drive device or the like that rotates a floppy disk.

[Summary of the Invention] The present invention provides a motor in which a shaft of a rotor is rotatably supported on a bearing of a stator, and the stator and rotor are opposed to each other with a predetermined clearance therebetween. Attaching a magnet with an unbalanced magnetic attraction or repulsion force so as to attract or repel the rotor toward the stator and to cause the shaft of the rotor to volatilize in one direction in the radial direction of the stator bearing. This makes it possible to reliably absorb backlash and axial vibration in the radial and thrust directions of the rotor sleeve with a simple structure and at low cost.

[Prior Art] For example, a turntable of a disk drive device that rotates a floppy disk is rotated by a spindle motor. To briefly explain this using Figure 3, 20 is a chuck yoke (turntable).
It is a simple iron core type spindle motor that rotates the 2+. This spindle motor 20 has a shaft (spindle) 24 of a rotor 23 consisting of a rotor yoke 22, rotor magnets (not shown), etc., and a stator 2 consisting of a stator yoke, multi-phase drive coils (none of which are shown), etc.
It is configured such that it is rotatably supported by a pair of ball bearings 27 and 27 fitted in a substantially cylindrical housing 26 as a bearing.

In order to absorb backlash in the thrust direction of the shaft 24 of the rotor 23 and to stably rotate the pair of ball bearings 2727, a wave is inserted between the lower ball bearing 27 and the rotor yoke 22 via a ring 28. The pair of ball bearings 2727 are constantly pressed upward (a constant preload is applied) with the washer (slope spring) 29 interposed.

[Problems to be Solved by the Invention] However, as described above, the conventional spindle motor 20 uses an expensive ball bearing 27 in order to absorb the backlash of the shaft 24 of the rotor 23 in the thrust direction.
A pair of upper and lower ball bearings 27 are provided, and this pair of ball bearings 27
．． In order to stably rotate the ball bearings 27, a plate spring such as a wave washer 29 is used to constantly push the pair of ball bearings 27 upward, which makes the overall structure complicated and increases costs. There was a disadvantage.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a motor that has a simple structure and low cost and can reliably absorb backlash and axial vibration in the thrust direction and radial direction of the rotor shaft.

[Means for solving the problem] In a motor in which a shaft of a rotor is rotatably supported on a bearing of a stator, and the stator and rotor are opposed to each other with a predetermined clearance, the stator is opposed to the rotor of the stator. At the position, a magnet can be attached with an unbalanced magnetic attraction or repulsion force so as to attract or repel the rotor toward the stator and to press the shaft of the rotor in one direction in the radial direction of the stator bearing. be.

[Function] The rotor is attracted or repelled toward the stator by the unbalanced magnetic attraction or repulsion of the magnets attached to the stator, so that the backlash of the rotor shaft in the thrust direction is reliably absorbed. As a result, the rotor shaft is pressed in one direction in the radial direction of the stator bearing, so that radial backlash and shaft vibration of the rotor shaft are reliably absorbed.

[Example] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a ferrous core type spindle motor used in a disk drive device, and is composed of a rotor 2 and a stator 3 that rotatably supports the rotor 2. As shown in FIG.

The rotor 2 includes, for example, a substantially disk-shaped rotor yoke 4,
A single shaft (spindle) 7 protrudes vertically upward through a boss fixed to the center of the rotor yoke 4 with a screw 5;
It is roughly composed of a chuck yoke (turntable) 8 press-fitted into the upper part of the shaft 7, a large-diameter annular rotor magnet (not shown) fixed to the outer circumferential side of the upper surface of the rotor yoke 4, etc. .

The stator 3 is fitted into a plate-shaped stator yoke 9 and a center hole 9a formed approximately in the center of the stator yoke 9, and is secured to the stator yoke 9 by a plurality of screws 10.
A cylindrical housing 11 has a circular disc-shaped flange 11a attached to the lower surface thereof, and a bearing is press-fitted into the upper and lower parts of the housing 11 to rotatably support the shaft 7 of the rotor 2. It is equipped with a ball bearing 12, an oil-impregnated bearing 13 made of resin, and a plurality of phase drive coils [4] facing each other with a predetermined clearance from the rotor magnet on the outer peripheral side, and the lower surface of the flange 11a of the housing 11. A pair of upper and lower disc-shaped annular iron cores 15, 1'6 are fastened and fixed to the sides by the above-mentioned screws 10, respectively, and a small-diameter disc-shaped annular magnet is fixed to the lower iron core 16 with adhesive or the like. ! It is roughly composed of 7.

The magnet 17 magnetically attracts the rotor yoke 4 toward the stator 3 and presses the shaft 7 of the rotor 2 in one radial direction of the bearings 12 and 13 of the stator 3 (for example, the left side in FIG. 1). The force is set to be unbalanced, and the rotor yoke 4 faces the upper surface of the rotor yoke 4 with a predetermined clearance. In other words, this magnet 17 strongly magnetizes the half of the annular disc (left side in the figure) and weakly magnetizes the remaining half (right side in the figure), thereby eliminating the magnetic attraction force. It is in equilibrium.

The attraction force of the magnet 17 can be varied depending on the magnetic flux (KG) on the magnet surface and the magnet surface area (mm''), so it is not limited to the case where the magnetic attraction force is made unbalanced by the magnetization, and it is possible to The magnetic attraction force of the magnet may be made unbalanced by fixing a plate-shaped ferromagnetic material and a weak magnetic material, or, for example, the magnetic attraction force of the magnet may be increased by removing a part of the magnet and changing the surface area. The magnetic attraction force of the magnet 17 may also be made unbalanced by changing the wall thickness of the magnet or by changing the air gap.

The magnet 17 has three small holes 17λ formed at equal intervals (every 120 degrees), and each of these small holes 17λ
The head of the screw 10 is exposed from 7a.

According to the spindle motor l of the above embodiment, the stator 3
Magnet attached to! Due to the magnetic attraction of 7,
Since the rotor yoke 4 is attracted toward the stator 3 (upward) as shown by the arrow in the figure, it is possible to reliably absorb and remove backlash of the shaft 7 of the rotor 2 in the thrust direction. Further, due to the unbalanced magnetic attraction force of the magnet 17, the rotor 2 1d17 is pressed in one direction (left side in the figure) in the radial direction of the bearing 12.13 of the stator 3, so that the shaft 7 of the rotor 2 Radial backlash and shaft runout can be reliably absorbed and removed.

In addition, since the shaft 7 of the rotor 2 is always pressed upward by the magnetic attraction force of the magnet 17 (a constant pressure preload is applied), the ball bearing 12 is made into a tortoise piece, and the other is an oil-impregnated bearing made of inexpensive resin. 13, the thrust backlash of the shaft 7 of the rotor 2 can be sufficiently absorbed, and a motor can be provided at a correspondingly low cost. In this case,
The upper and lower positions of the ball bearing 12 and the oil-impregnated bearing 13 may be changed, and since they are simply press-fitted into the housing 11 and there is no need to bond them with an adhesive or the like, costs can be further reduced. In this way, the thrust direction, radial direction, and shaft vibration of the shaft 7 of the rotor 2 are prevented.
This can be done by simply managing the amount of magnetic flux (surface magnetic flux) of the magnet 17, so the structure is simpler and lower cost than conventional ones, and the ball hair ring 12
It is possible to obtain a constant pressing amount with little variation in the pressing force m (preload amount).

FIG. 2 shows another embodiment of a spindle motor. This spindle motor l' has the same magnetic pole (N
The spindle motor 1 is the same as the spindle motor 1 of the above embodiment except that the magnets (18 and 19) are each attached by fixing them with an adhesive or the like. Therefore, the same reference numerals are given and detailed explanation thereof will be omitted. The magnet 18 also repels the rotor 2 toward the stator 3 by changing the magnetization strength on the left and right sides in the figure, as in the embodiment described above, and also aligns the shaft 7 of the rotor 2 with the shaft 7 of the bearing 1213 of the stator 3 in the radial direction. The magnetic repulsion force is set to be unbalanced so as to push in the direction (left side in the figure).

The repulsive force of these magnets 18 and 19 and the magnet 1
Since the shaft 7 of the rotor 2 is pushed downward as shown by the arrow in the figure due to the imbalance of the magnetic repulsion of the rotor 2, the backlash of the shaft 7 of the rotor 2 in the thrust direction can be reliably absorbed, as in the previous embodiment. It can be removed by Furthermore, due to the unbalanced magnetic repulsion force of the magnet 18, the shaft 7 of the rotor 2 is pressed in one direction (left side in the figure) in the radial direction of the bearings 12 and 13 of the stator 3. Furthermore, the radial backlash and shaft vibration of the shaft 7 of the rotor 2 can be reliably absorbed and removed.

Incidentally, according to the above-mentioned embodiment, the magnets 18 and 19 are respectively arranged at positions where the stator 3 and the rotor 2 face each other so that the same magnetic 1 ft (N poles) face each other, but different magnetic poles Each magnet may be arranged so that the (S and N poles) face each other so that the two magnets are attracted to each other.

[Effects of the Invention] As described above, according to the present invention, the rotor is attracted or repelled toward the stator at a position opposite to the rotor of the stator, and the shaft of the rotor is aligned in the radial direction of the bearing of the stator. Since the magnet is installed with an unbalanced magnetic attraction or repulsion force so as to push it in one direction, it has a simple structure and low cost, and ensures that the rotor shaft does not shake in the lanoidal direction and the thrust direction and swing out. can be absorbed respectively.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a motor according to an embodiment of the present invention;
The figure is a sectional view showing a motor of another embodiment, and FIG. 3 is a sectional view showing a conventional motor. 1. Motor, 2. Rotor, 3-way stator,
7...Shaft, 12.13...Bearing, 17.18...Magnet. 6゜Amendment contents procedure amendment document. , ■. Display of the case 1988 Patent Application No. 161949 2゜ Name of the invention Motor 3゜ Person making the amendment Relationship to the case Applicant (218) Sony Corporation 4゜ Embedded address 1 Akashicho, Chuo-ku, Tokyo 104 No. 29 Suiseikai Building 5° Subject of amendment (1) “Detailed description of the invention” column of the specification. (1) The phrase "floppy disk" on page 1, line 16 of the Middle East specification is corrected to read "disk." (2) "Floppy disk" on page 2, line 16 of the specification should be corrected to "disk." (3) The phrase "stator yoke" on page 3, line 4 of the Middle East specification is amended to read "stator base." (4) "Stator yoke 9" in the 9th, 10th, and 12th lines of page 6 of Specifications for Cattle are corrected to "stator base 9." (5) The words "made of resin" on page 6, line 16 and page 9, line 6 of the Middle East specification are amended to read "made of sintered metal." (6) Correct Figure 3 as shown in the attached sheet. Figure 3

Claims (1)

[Claims] (1) In a motor in which a shaft of a rotor is rotatably supported in a bearing of a stator, and the stator and rotor are opposed to each other with a predetermined clearance, the rotor is placed in a position opposite to the rotor of the stator. 1. A motor characterized in that a magnet is attached, the magnetic attraction or repulsion force being set unbalanced so as to attract or repel the shaft of the rotor in one direction in the radial direction of the bearing of the stator.