JP4121143B2 - Brushless motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brushless motor used for driving a disk such as a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, and a DVD-RW.
[0002]
[Prior art]
CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, a conventional brushless motor used to drive the removable disk such as a DVD-RW, for example, a structure shown in FIG. 2 It has been known.
[0003]
This conventional brushless motor includes a shaft 110 rotatably supported by a bush 104 and a sleeve 108 which are fixing members, a rotor frame 115 which is externally fixed to the shaft 110 and rotates integrally, and a rotor frame 115. The mounted rotor magnet 116 and the stator 106 fixed to the bush 104 and opposed to the rotor magnet 116 in the radial direction are provided.
[0004]
A turntable 120 is fitted and fixed to an outer portion in the axial direction from the rotor frame 115 of the shaft 110, and an annular recess 120 a is provided on the inner peripheral portion of the turntable 120.
[0005]
An annular yoke 126 is fixed in the recess 120a of the turntable 120, and the fixing portion 126a provided in the yoke 126 is fitted to the resin pin 120b provided in the recess 120a. Thereafter, a method of melting and welding the resin pins 120b is used.
[0006]
An annular clamp magnet 128 is fixed to the upper end surface of the yoke 126 by means such as adhesion.
[0007]
In the brushless motor having the above construction, when the disk 124 on the turntable 120 is placed, by the clamp magnet 128, the clamp member 130 of the drive unit side shown by a two-dot chain line in FIG. 2 is magnetically attracted, thereby the turntable The disk 124 is held on 120.
[0008]
[Problems to be solved by the invention]
However, in the method (welding) in which the resin pin 120b of the turntable 120 is melted and fixed to the yoke 126, there is an error in the welding of the resin pin 120b depending on the management of the melting temperature, melting time or cooling time of the resin pin 120b. May occur.
[0009]
That is, in the manufacturing process, in the method of welding the resin pin 120b to the yoke 126 by ultrasonic welding or heat welding, if the melting time for melting the resin pin 120b is too long, the resin pin 120b may be melted too much, The resin may adhere to the welding tool consisting of the heating pin, which may hinder the next process.
[0010]
If the melting time of the resin pin 120b is too long, the turntable 120 itself formed of resin is deformed in the same manner as the resin pin 120b, the parallelism between the yoke 126 and the turntable 120 is lost, and the turntable 120 is lost. The magnetic attractive force with respect to the clamp member 130 by the clamp magnet 128 is affected by the dimensional accuracy from the disk 124 mounting surface to the upper end surface of the clamp magnet 128 fixed to the upper end surface of the yoke 126.
[0011]
When the magnetic force acting between the clamp magnet 128 and the clamp member 130 varies as described above, the holding force of the disk 124 by the clamp member 130 becomes uneven in the circumferential direction, and the disk 124 can be stably held. Not only is it difficult, but also reading and writing to the disk 124 by the drive device becomes difficult. In addition, the centrifugal force may exceed the magnetic force acting between the clamp magnet 128 and the clamp member 130 during high-speed rotation, and the clamp member 130 may come off and the disk 124 may scatter.
[0012]
On the contrary, if the melting time is too short, the resin pin 120b is not sufficiently melted and the welding of the yoke 126 to the turntable 120 becomes insufficient.
[0013]
If the resin pin 120b and the yoke 126 are not sufficiently welded as described above, the yoke 126 is peeled off from the resin pin 120b, and the disk 124 cannot be held by the clamp member 130 itself.
[0014]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to avoid a non-uniform holding force with respect to a disk by a clamp member and to achieve a uniform quality of process work, thereby achieving a highly reliable brushless motor. Is to provide.
[0015]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the brushless motor according to claim 1 of the present invention, a shaft, a turntable that rotates integrally with the shaft, and a yoke disposed on an inner peripheral portion of the turntable, In a brushless motor comprising
The yoke is fixed to the shaft.
[0016]
The brushless motor according to claim 2 of the present invention is characterized in that a gap is provided between the yoke and the turntable.
[0017]
The brushless motor according to claim 3 of the present invention is characterized in that an adhesive is filled in a gap between the yoke and the turntable.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a brushless motor according to an embodiment of the present invention will be described with reference to FIG. This brushless motor is for rotating a disk such as a CD-ROM. In the description of the present embodiment, the vertical direction of each drawing is referred to as the “vertical direction” for convenience, but the direction in the actual mounting state is not limited.
[0019]
The brushless motor shown in FIG. 1 includes a frame 2 having a through hole 2a in the center, and a cylindrical bush 4 formed of iron, stainless steel or the like is inserted into the through hole 2a. The bushing 4 and the frame 2 are fixed by plastically deforming the caulking portion 4a provided at the lower part of the metal plate 4 outward in the radial direction.
[0020]
The bush 4 is configured as an opening having an upper end opened, a stator 6 is fixed to the outer periphery thereof by means such as adhesion, and a hollow cylinder impregnated with lubricating oil is provided on the inner periphery. A sleeve 8 of a porous sintered body is press-fitted and fixed. A thrust receiving plate 12 made of a resin material having excellent wear resistance and heat resistance is disposed at the bottom of the inner peripheral portion of the bush 4.
[0021]
A shaft 10 is rotatably inserted into the sleeve 8. At the time of rotation, the shaft 10 is supported by the inner peripheral surface of the sleeve 8 from the radial direction via the lubricating oil, and has a circular arc shape in cross section. The lower end is supported from the axial direction by contacting the thrust receiving plate 12.
[0022]
A stepped portion 4b is formed at the lower end portion of the inner peripheral surface of the bush 4 by, for example, pressing.
[0023]
An annular ring member 14 having an inner diameter smaller than the outer diameter of the shaft 10 is placed on the stepped portion 4b, and the lower end surface of the sleeve 8 is brought into contact with the upper end surface of the ring member 14, whereby the ring member 14 is clamped by the step part 4b and the sleeve 8 from the axial direction.
[0024]
An annular groove 10a is formed on the outer peripheral surface of the shaft 10 corresponding to the ring member 14, and the ring member 14 and the annular groove 10a are engaged with each other to prevent the shaft 10 from being removed.
[0025]
A cup-shaped rotor frame 15 is press-fitted and fixed to the shaft 10 which is a rotating member on the upper side in the axial direction of the upper ends of the bush 4 and the sleeve 8.
[0026]
The rotor frame 15 is formed of a magnetic material such as iron or stainless steel, and a rotor magnet 16 is fixed to the inner peripheral surface thereof by adhesion or the like so as to face the stator 6 fixed to the bush 4 in a radial direction with a gap therebetween. Has been.
[0027]
A hall element 18 is fixed to the frame 2 for detecting the rotational position at a position facing the rotor magnet 16 in the axial direction.
[0028]
A disc-shaped turntable 20 is fixed to the shaft 10 at the upper part in the axial direction of the rotor frame 15 by a combination of adhesion and press-fitting. An adhesive groove 10b is provided on the outer peripheral surface of the shaft 10 to which the turntable 20 is fixed, and the adhesive squeezed by press-fitting is accommodated in the adhesive groove 10b.
[0029]
The turntable 20 is a member molded from a resin or the like, and an annular cushioning material 22 is provided on the outer peripheral portion thereof. On the cushioning material 22, a disk 24 indicated by a one-dot chain line in the figure is placed.
[0030]
An annular recess 20a is provided in the inner periphery of the turntable 20, and a yoke 26 is disposed in the recess 20a as described later.
[0031]
The yoke 26 is an annular member formed by pressing a ferromagnetic material such as iron or stainless steel, and is fixed to the upper end portion of the outer peripheral surface of the shaft 10 by press fitting.
[0032]
A clamp magnet 28 having substantially the same outer diameter is bonded and fixed to the upper surface of the yoke 26. The yoke 26 and the clamp magnet 28 are accommodated with a gap between the bottom surface and the inner peripheral surface of the recess 20a.
[0033]
The clamp magnet 28 magnetically attracts the clamp member 30 on the drive device side indicated by a two-dot chain line in the drawing in the axial direction. With this magnetic attraction force, the clamp member 30 presses the disk 24 placed on the cushioning material 22 of the turntable 20 downward in the axial direction, whereby the disk 24 is held by the turntable 20. .
[0034]
As described above, the yoke 26 is not affected by the displacement of the fixing position of the turntable 20 by being press-fitted into the shaft 10 and fixed so as to have a gap between the yoke 20 and the recess 20a. The positioning of the fixed part can be arbitrarily set.
[0035]
In addition, the press-fit fixing of the yoke 26 and the shaft 10 with metal can make the fixing strength uniform, so that the quality of the process work can be made uniform, and the working efficiency is improved.
[0036]
In addition, the height and parallelism of the clamp magnet 28 can be set by the yoke 26, and processing errors in the component dimensions of each member can be corrected during assembly, so that the disk 24 on the cushioning material 22 of the turntable 20 can be placed. The magnetic attraction force to the clamp member 30 of the clamp magnet 28 resulting from the dimensional accuracy from the surface to the upper end surface of the clamp magnet 28 can be kept constant in the circumferential direction, and the yield is also increased.
[0037]
Note that an adhesive or the like may be filled in the gap between the lower surface of the yoke 26 and the bottom surface of the turntable 20 recess 20a.
[0038]
By doing so, the press-fitting and fixing of the yoke 26 to the shaft 10 enhances the strength of the fixing of the turntable 20 that is a resin material by bonding and press-fitting to the shaft 10 and the parallelism of the yoke 26 and the turntable 20. This is because it can be ensured with higher accuracy.
[0039]
As mentioned above, although embodiment which concerns on this invention was described, this invention is not limited to the above-mentioned embodiment, A various deformation | transformation is possible.
[0040]
For example, in the above-described embodiment, the configuration in which the yoke 26 and the clamp magnet 28 are provided on the motor side has been described. However, the clamp magnet is provided on the driving device side such as a clamp member, and the motor side is configured only with the yoke. The same action and effect as the form can be obtained.
[0041]
【The invention's effect】
The brushless motor according to claim 1, by the yoke is fixed to the shaft side, it becomes possible to maintain the parallelism between the yoke and the turntable easily and reliably, stably disk Can be held.
[0042]
Further, in the brushless motor according to claim 1, yoke and a gap is provided between the turntable, by that they are not in contact with each other, without being affected by displacement of fixed positions of the turntable, the shaft The positioning of the fixed part relative to can be arbitrarily set.
[0043]
In the brushless motor according to claim 2, the adhesive between the yoke and the turntable is filled with an adhesive, whereby the strength of fixing the yoke and the turntable to the shaft can be increased, and the yoke and the turntable. The parallelism can be ensured even better.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a conventional brushless motor.
[Explanation of symbols]
2 Frame 4, 104 Bush 4b Stepped portion 6, 106 Stator 8, 108 Sleeve 10, 110 Shaft 15, 115 Rotor frame 16, 116 Rotor magnet 20, 120 Turntable 20a, 120a Recess 120b Resin pin 22 Buffer material 24, 124 Disc 26, 126 Yoke 126a Fitting portion 28, 128 Clamp magnet 30, 130 Clamp member

Claims (3)

In a brushless motor comprising a shaft, a turntable that rotates integrally with the shaft, and a yoke disposed on an inner peripheral portion of the turntable,
The turntable is fixed to the shaft;
The yoke is fixed to the shaft;
The yoke and the brushless motor between the turntable, the gap is provided, which is characterized in that they are not in contact with each other. Said yoke and said the gap between the turntable, a brushless motor according to claim 1 Symbol mounting adhesive has characterized in that it is filled. 3. The brushless motor according to claim 1, wherein a clamp magnet having substantially the same outer diameter as that of the yoke is bonded and fixed on the yoke.

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