JP2009072007A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor which is simple in a shape of a component, and is inexpensive while maintaining strength and accuracy. <P>SOLUTION: The brushless motor includes a rotor 10 which has a rotor case 11, a shaft 12 fixed to the rotor case 11, and a magnet 13 fixed to an inner peripheral face of the rotor case 11, a bearing to rotatably support the shaft 12, a bearing holder 24 to hold the bearing, a stator core 27 which is arranged oppositely to the magnet 13, and around which a coil 26 is wound, and a stator base 21 on which a printed wiring board 22 is mounted, whererin a terminal of the coil 26 is connected to the printed wiring board. In the brushless motor, a bar ring portion 21a provided at the stator base 21 is fitted with a throughhole 24c provided at a flange portion 24b of the bearing holder 24, then the stator core 27, the bearing holder 24, and the stator base 21 are screwed in the bar ring portion 21a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an outer rotor type brushless motor used for driving a disk such as an optical disk or a magnetic disk.

  For example, Patent Document 1 discloses a brushless motor for rotating a disk used in a mini disk (MD) of an optical disk device.

As shown in FIG. 4, the brushless motor described in Patent Document 1 has a rotating shaft 112 and a magnet 113 fixed to a central portion of a cup-shaped rotor case 111 and an inner peripheral surface thereof. A ring-shaped preloading magnet 114 is fixed to the peripheral surface portion 111 a of the insertion base portion of the rotating shaft 112.
A stator core 127 around which a coil 126 is wound is fixed to the outer peripheral side of the bearing holder 124, and the terminal of the coil 126 is connected to a connection pattern of a printed wiring board 122 provided on the upper surface of the stator base 121 by soldering or the like. The
A radial bearing 123 and a thrust bearing 123 a are held inside the bearing holder 124, and the bearing holder 124 is fixed to the stator base 121.
Reference numeral 130 denotes a turntable on which an information recording disk is placed, and is inserted into the output side end of the rotating shaft 112.

JP 2003-79095 A

  Since the bearing portion of such a brushless motor is required to have accuracy and strength, conventionally, the bearing holder 124 is formed with high precision by cutting a brass member, and then firmly fixed to the stator base 121 by caulking or press-fitting. I was trying to fix it.

  However, with such a configuration, the bearing holder 124 is expensive in terms of both material and processing, which has been an obstacle to lowering the motor cost.

Further, since the bearing holder 124 is fixed to the stator base 121 by caulking or press-fitting, there is a problem that the stator base 121 and the bearing holder 124 are deformed and the shaft perpendicularity is finally deteriorated.
Further, when the bearing holder 124 is fixed to the stator base 121 by caulking, the bottom portion of the bearing holder 124 protrudes from the lower surface of the stator base 121, which not only obstructs the low profile of the motor, There was also a problem that the mounting surface was limited.

  In addition, since not only the bearing holder 124 but also the stator core 127 has been fixed by press fitting, disassembly is difficult and repair and reuse are virtually impossible.

  An object of the present invention is to solve these problems and provide an inexpensive brushless motor while maintaining strength and accuracy with a simple component shape.

  The brushless motor of the present invention configured to achieve the above object is a rotor having a rotor case, a shaft fixed to the rotor case, and a magnet fixed to an inner peripheral surface of the rotor case, A bearing that rotatably supports the shaft, a bearing holder that holds the bearing, a stator core that is disposed opposite to the magnet and wound with a coil, and a printed wiring board to which the end of the coil is connected are placed. A brushless motor including a stator base, wherein the bearing holder has a flange portion mounted on the stator base, the stator core has an annular portion on an inner peripheral side, and the annular portion is used as the bearing holder. It is characterized by being screwed to the stator base together with the bearing holder in a state of being placed on the flange portion.

As a further preferable feature of the brushless motor of the present invention,
“A burring portion provided in the stator base is fitted into a through-hole provided in the flange portion of the bearing holder, and the stator core, the bearing holder, and the stator base are screwed to the burring portion.” ,
“A cap that covers the open end of the bearing holder is screwed together with the stator core in a state of being placed on the annular portion of the stator core.”
"The cap functions as a retaining means for the rotor",
Is included.

  According to the brushless motor of the present invention, the bearing holder and the stator core can be fixed without caulking or press-fitting, and can be repaired and reused while maintaining the accuracy and strength by suppressing the deformation of the stator base with a simple component shape. An inexpensive brushless motor can be realized. In addition, by adjusting the tightening torque of a plurality of screws, the shaft suspension can be easily adjusted, and a more accurate brushless motor can be realized. Furthermore, since the lower surface of the stator base can be made flat, the motor can be thinned, and the mounting surface is not limited, and the versatility is high.

  In addition, a burring portion provided in the stator base is fitted into a through hole provided in the flange portion of the bearing holder, and in the burring portion, the stator core, the bearing holder, and the stator base are screwed. The positioning of the bearing holder can be performed automatically and the assembly is easy, and a high-strength motor can be realized even if a thin stator base is used.

  Also, in the case where a cap covering the open end of the bearing holder is screwed together with the stator core in a state of being placed on the annular portion of the stator core, especially when an oil-impregnated bearing is used as the bearing, the lubrication oil scattering prevention of the bearing is prevented. Means can be easily assembled.

  Further, when the cap is used as a means for preventing the rotor from coming off, one member can have a plurality of functions, and the number of members and assembly man-hours can be reduced.

  Hereinafter, embodiments of the present invention will be exemplarily described based on the drawings. However, the material, shape, relative arrangement, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(First embodiment)
FIG. 1 shows a brushless motor according to the present embodiment, and the right side of the center line shows a cross section. FIG. 2 is an assembly view of the motor.
The brushless motor includes a rotor 10 and a stator 20 that rotatably supports the rotor 10.

The rotor 10 is fixed to a rotor case 11 formed of a metal material having a magnetic body in a bottomed cylindrical shape, a shaft 12 press-fitted and fixed to the center of the rotor case 11, and an inner peripheral surface of the rotor case 11. A disk guide 14 and a friction sheet 15 are fixed to the upper surface of the rotor case 11 so as to function as a turntable. The turntable may be fixed to the shaft 12 separately from the rotor case 11 like the conventional one in FIG.
A disk (not shown) is placed on a turntable provided in the rotor 10, and the disk is centered by a disk guide 14.

  The stator 20 includes a stator base 21 on which a flexible printed wiring board 22 on which a hall element and a drive member (not shown) are arranged is placed and fixed, a radial bearing 23a and a thrust bearing 23b that rotatably support the shaft 12, A bearing holder 24 that holds the outer periphery of the radial bearing 23a, a cap 25 for preventing oil leakage, and a stator core 27 on which a coil 26 is wound so as to face the magnet 13 are provided.

The stator base 21 is provided with a recess 21b for accommodating the thrust bearing 23b and three burring portions 21a, and the inside of the burring portion 21a is threaded.
The bearing holder 24 is made of metal having a cylindrical portion 24a and a flange portion 24b. The flange portion 24b is placed on the stator base 21, and a burring portion 21a of the stator base 21 is inserted into a through hole 24c provided in the flange portion 24b. Is inserted.

  A thrust bearing 23b is accommodated in the concave portion 21b of the stator base 21, and a radial bearing 23a in which a cylindrical sintered metal is impregnated with a lubricating oil is press-fitted into the cylindrical portion 24a of the bearing holder 24, and the shaft 12 The rotor 10 can be freely rotated by being supported by the bearings.

  The stator core 27 is composed of a laminated plate of plate-like cores in which an annular portion 27a on the inner peripheral side provided with a through hole 27c and a plurality of salient poles 27b connected to the outer periphery of the annular portion 27a are formed. A coil 26 is wound around the pole with an insulating sheet 28 inserted.

  The printed wiring board 22 and the stator base 21 facing the lower portion 26 a of the coil 26 are provided with a storage hole 21 c that avoids interference with the coil 26. Therefore, the height of the stator core 27 can be lowered by the height of the lower portion 26a of the coil 26, and the motor can be reduced in height.

  The stator core 27 is disposed such that the annular portion 27a surrounds the outer periphery of the cylindrical portion 24a of the bearing holder 24 in a state where the annular portion 27a is placed on the flange portion 24b of the bearing holder 24, and the plurality of salient poles 27b are magnets. 13 are arranged opposite to each other through a space.

  The brushless motor of this example is provided with an oil leakage preventing cap 25 that covers the open end of the bearing holder 24. The cap 25 has a hole 25a through which the shaft 12 penetrates in the center, and the shaft 12 can rotate without contacting it while maintaining a slight gap with the hole diameter. The cap 25 is made of resin and has a bottomed cylindrical shape, and has a circular flange 25b extending outward in the radial direction on the periphery thereof, and a through hole 25c is provided in the flange 25b.

  The through hole 25c of the cap 25, the hole 27c of the stator core 27, and the through hole 24c of the bearing holder 24 are screwed together by the burring portion 21a of the stator base 21, and are equally spaced at 120 degrees as shown in FIG. There are three places.

  In addition, a ring-shaped energizing magnet that is magnetized within an opening angle of 180 degrees when viewed from the top so as to face the top surface 11b of the rotor case 11 made of a magnetic material at the end of the bearing holder on the rotor side. M is provided so that the center thereof coincides with the center of the shaft 12. Therefore, it is always urged in the radial direction with a constant force, and a stable rotation performance of the motor can be realized.

  With such a configuration, the brushless motor can rotate the rotor 10 relative to the stator 20 by energizing the coil 26 from a driving member (not shown).

  When assembling the brushless motor of this example, first, the printed wiring board 22 on which the Hall element and the driving member are arranged is fixed on the stator base 21, and then the bearing holder 24 is mounted and the through hole provided in the flange portion 24b. The burring portion 21a of the stator base 21 is fitted into 24c. As a result, the bearing holder 24 is automatically positioned on the stator base 21.

  Next, a thrust bearing 23b is disposed in the recess 21b of the stator base 21, and after the radial bearing 23a is press-fitted into the cylindrical portion 24a of the bearing holder 24, the stator core 27 is disposed on the outer periphery of the cylindrical portion 24a of the bearing holder 24, Further, the cap 25 is disposed on the stator core 27.

  Next, the cap 25, the stator core 27, the bearing holder 24, and the stator base 21 are screwed at once by the screw material 29 from the cap 25 side using the burring portion 21a that has been threaded. At this time, the screw material 29 is prevented from protruding from the back surface of the stator base 21.

Next, the rotor 10 is inserted into the stator 20 from above.
Finally, a screwdriver is inserted from the through hole 11a provided in the rotor case 11, and the tightening torque of the three screw members 29 is finely adjusted to adjust the shaft perpendicularity.

  According to the present embodiment described above, the bearing holder 24 and the stator core 27 can be fixed while maintaining strength without being caulked or press-fitted, and a high accuracy brushless motor can be obtained by adjusting the shaft perpendicularity even with a simple component shape. be able to.

Further, since the bearing holder 24 and the screw material 29 do not protrude from the back surface of the stator base 21 and the lower surface of the stator base can be flattened, the motor can be thinned and the mounting surface is not limited when the motor is mounted. It becomes a thing with high property.
Furthermore, the motor can be easily disassembled with a screwdriver alone, and can be repaired and reused.

  Further, the bearing holder 24 can be positioned automatically by fitting the burring portion 21a provided in the stator base 21 into the through hole 24c provided in the flange portion 24b of the bearing holder 24. In addition to being easy, since the burring portion 21a is threaded, a sufficient number of threads can be formed even with a thin stator base, and the strength of screwing can be increased.

  Further, since the oil leakage preventing cap 25 can be fixed together with the stator core 27, the bearing holder 24 and the stator base 21 by screwing together, the lubricating oil scattering preventing means for the radial bearing 23a can be easily assembled.

  When the burring portion 21a of the stator base 21 is formed high enough to enter the through hole 27c of the stator core 27, not only the bearing holder 24 but also the stator core 27 can be positioned automatically, and the assembly can be performed more easily. It becomes easier.

(Second Embodiment)
FIG. 3 shows a brushless motor according to the second embodiment. In FIG. 3, the same components as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

This embodiment is different from the first embodiment in that an oil leakage prevention cap 25 is made to function as a means for preventing the rotor from coming off.
For this reason, in the present embodiment, the groove 12a is provided in the substantially central entire circumference of the shaft 12, and the three claw portions 25d are provided in the inner peripheral portion of the cap 25. However, when the rotor moves in the axial direction, the tip end portion of the claw portion 25d is caught in the groove 12a, so that the rotor is prevented from coming off.

  When the motor is assembled, the shaft 12 can be passed downward in the axial direction while elastically deforming the claw portion 25d of the cap 25, and the axial movement of the shaft 12 can be restricted after assembly. The cap 25 may be made of resin or metal as long as the claw portion 25d can be elastically deformed.

  According to the present embodiment, in addition to the effects of the first embodiment, the cap can be provided with a function of preventing the oil leakage as well as a function of preventing the rotor from coming off, and the number of members and assembly man-hours can be reduced.

It is a brushless motor concerning a 1st embodiment of the present invention, and the right side from a center line shows a section. 1 is an assembly diagram of a brushless motor according to a first embodiment of the present invention. It is the brushless motor concerning the 2nd Embodiment of this invention, and the right side from the centerline has shown the cross section. It is sectional drawing of the conventional brushless motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotor 11 Rotor case 11a Through-hole 11b Top surface 12 Shaft 12a Groove 13 Magnet 14 Disc guide 15 Friction sheet 20 Stator 21 Stator base 21a Burring part 21b Recess 21c Storage hole 22 Printed wiring board 23a Radial bearing 23b Thrust bearing 24 Bearing holder 24a Cylindrical part 24b Flange part 24c Through hole 25 Cap 25a Hole 25b Flange 25c Through hole 25d Claw part 26 Coil 26a Lower part 27 Stator core 27a Annular part 27b Salient pole 27c Through hole 28 Insulating sheet 29 Screw member 111 Rotor case 111a Circumferential surface part 112 113 Magnet 114 Preload Magnet 121 Stator Base 122 Printed Wiring Board 123 Radial Bearing 123a Thrust Bearing 124 Bearing Holder 126 Carp 127 stator core 130 turntable M-biasing magnet

Claims (4)

A rotor having a rotor case, a shaft fixed to the rotor case, and a magnet fixed to an inner peripheral surface of the rotor case;
A bearing that rotatably supports the shaft, a bearing holder that holds the bearing, a stator core that is disposed facing the magnet and wound with a coil, and a printed wiring board to which the end of the coil is connected are placed. A brushless motor comprising a stator base,
The bearing holder has a flange portion mounted on the stator base,
The stator core has an annular portion on an inner peripheral side, and is screwed to the stator base together with the bearing holder in a state where the annular portion is placed on the flange portion of the bearing holder. Brushless motor.   A burring portion provided in the stator base is fitted into a through hole provided in the flange portion of the bearing holder, and the stator core, the bearing holder, and the stator base are screwed to the burring portion. The brushless motor according to claim 1.   The brushless motor according to claim 1, wherein a cap that covers an open end of the bearing holder is screwed together with the stator core in a state of being placed on the annular portion of the stator core.   The brushless motor according to claim 3, wherein the cap functions as a retaining means for the rotor.

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