JP5158845B2 - Brushless motor - Google Patents

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, and more particularly to a retaining mechanism that prevents a rotor from coming out of a stator.

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

  Since the outer rotor type brushless motor described in Patent Document 1 has a structure in which the shaft is supported by the bearing in the bearing holder, a rotor retaining mechanism is required to prevent the shaft from coming out of the bearing holder. And

  As a rotor retaining mechanism, a shaft groove is provided near the lower end of the shaft, and a ring-shaped retaining member is disposed at the lower end of the inner peripheral portion of the bearing holder. When this retaining member is fitted in a shaft groove formed on the shaft, the rotor can be prevented from slipping against movement in the axial direction.

JP-A-8-33261

  However, since the conventional rotor retaining mechanism is disposed in the axially lower portion of the bearing, the axial height of the brushless motor is increased, which is a major problem in achieving a thinner brushless motor. It was.

  Recently, brushless motors have been miniaturized, and as the outer diameter of the rotor has decreased, the diameter of the shaft has also decreased. At that time, as a rotor retaining mechanism, a shaft groove is provided in the shaft, and when a retaining member is fitted into the shaft groove, the shaft groove is small, so that the shaft groove cannot be deeply provided, and the axial rotor It was not possible to obtain a sufficient retaining strength.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a brushless motor provided with a mechanism for preventing a rotor from coming off and reducing the thickness of the brushless motor and reducing the size of the brushless motor.

The brushless motor of the present invention configured to achieve the above object is:
A rotor case, a shaft fixed to the center of the rotor case, and a rotor having a cylindrical magnet fixed to the inner peripheral surface of the rotor case;
A brushless motor comprising: a bearing that rotatably supports the shaft; a bottomed cylindrical bearing holder that fixes the bearing; and a stator that has a stator core that is disposed opposite to the magnet and wound.
The bearing holder is provided with a cap for preventing oil leakage covering the open end,
The cap has a hole through which the shaft passes, has a bottomed cylindrical shape, and has a flange on the periphery of the open end,
A washer is disposed between the flange and the winding;
An inner diameter of the washer is formed slightly larger than an outer diameter of the bearing holder, and the washer is movable in an axial direction between the flange and the winding;
The washer is characterized in that when the rotor moves in the axial direction, the washer functions as a retaining member that contacts the magnet and restricts the movement of the rotor in the axial direction .

As a further preferable feature of the brushless motor of the present invention,
"The washer has a shape obtained by cutting out a semicircle on the outer periphery" .

  According to the brushless motor of the present invention, since the retaining mechanism of the rotor is provided in the space between the inner peripheral surface of the rotor case and the outer peripheral surface of the bearing holder, the brushless motor can be reduced in thickness and size.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view of a brushless motor according to the present embodiment. FIG. 2 is an assembly diagram of the brushless motor according to the present embodiment. FIG. 3 is a perspective view of the cap.
1 to 3, the brushless motor 1 includes a rotor 10 and a stator 11 that rotatably supports the rotor 10.

  The rotor 10 includes a rotor case 12, a shaft 13 that is press-fitted and fixed to the center of the rotor case 12, and a cylindrical magnet 14 that is fixed to the inner peripheral surface of the rotor case 12. The rotor case 12 is formed of a metal material in a bottomed cylindrical shape and rotates integrally with the shaft 13.

On the inner peripheral surface of the rotor case 12, there is a step portion 15 on which the magnet 14 provided on the entire circumference is placed, and a locking portion 16 for positioning the magnet 14 is provided at the end of the step portion 15. . When the magnet 14 is inserted into the step portion 15, the magnet 14 comes into contact with the locking portion 16 and is fixed by an adhesive. The fixed magnet 14 has a shape in which the inner diameter portion protrudes inward in the radial direction as compared with the inner peripheral surface of the rotor case 12.
Note that the magnet 14 may be positioned by providing only a plurality of protrusions on the inner peripheral surface of the rotor case 12 without providing the step portion 15.

  On the other hand, the stator 11 includes a bearing 17 that rotatably supports the shaft 13, a bottomed cylindrical bearing holder 18 that fixes the bearing 17, and an oil leakage prevention cap 19 that covers the open end of the bearing holder 18. And a stator core 20 having a winding 22 disposed opposite to the magnet 14 and a stator base 21 for fixing the bearing holder 18.

  The bearing holder 18 has a metal bottomed cylindrical shape, and a sintered oil-impregnated bearing 17 is press-fitted from an open end thereof. Lubricating oil for smooth rotation with the shaft 13 is injected into the bearing holder 18. . The shaft 13 is supported by a bearing 17 and the rotor 10 can freely rotate.

A stator core 20 having a plurality of salient poles arranged opposite to the magnet 14 is fixed to the outer periphery of the bearing holder 18, and the stator core 20 is wound with a winding 22 according to the number of salient poles.
A stator base 21 is disposed and fixed at the lower end of the outer periphery of the bearing holder 18. On the stator base 21, a substrate 23 (not shown) on which Hall elements and driving members are arranged is provided.
With this configuration, the brushless motor 1 can rotate the rotor 10 relative to the stator 11 by energizing the winding 22 from the driving member.

  The brushless motor of this example is provided with a cap 19 that covers the open end of the bearing holder 18. The cap 19 has a hole 19a through which the shaft 13 passes in the center, and the shaft 13 can rotate without contact with the hole diameter while maintaining a slight gap. The cap 19 is made of resin and has a bottomed cylindrical shape, and has a circular flange 19b that spreads radially outward at the periphery of the open end. The outer diameter of the flange 19 b is designed to be larger than the inner diameter of the magnet 14 and smaller than the inner diameter of the rotor case 12. The cap 19 is fixed to the open end side of the bearing holder 18 by screwing, press-fitting, adhesive, or the like, and functions to prevent oil leakage.

When assembling the rotor 10 to the stator 11, the rotor 10 is inserted into the stator 11 from above as shown in FIG. The outer diameter of the flange 19b of the cap 19 is designed to be larger than the inner diameter of the magnet 14 and smaller than the inner diameter of the rotor case 12, but the flange 19b is made of resin and can be elastically deformed. The magnet 14 can pass downward in the axial direction, and the axial movement of the rotor 10 can be restricted after assembly.
Therefore, by providing the cap 19 at the open end of the bearing holder 18, the lubricating oil in the bearing holder 18 can be prevented from scattering inside the motor, and when the rotor 10 moves in the axial direction, the flange 19 b It can contact the magnet 14 in the rotor 10 and function as a retaining member.

As described above, according to the brushless motor 1 of the present embodiment, the retaining member that restricts the axial movement of the rotor 10 in the space between the inner peripheral surface of the rotor case 12 and the outer peripheral surface of the bearing holder 18 ( Since the cap flange) is provided, the brushless motor 1 can be reduced in thickness and size.
Further, since the oil leak prevention cap 19 also serves as a retaining member, the number of members and the number of assembly steps can be reduced.

  In the above embodiment, the cap 19 is made of resin, but a thin metal plate may be used as long as the flange 19b has elasticity. In this case, a thin metal plate is formed into a cylindrical shape with a bottom by pressing, and a flange 19b is formed on the periphery of the open end.

(Second Embodiment)
FIG. 4 is a sectional view of the brushless motor according to the present embodiment. In FIG. 4, the same components as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the present embodiment, the difference from the first embodiment is that, as shown in FIG. 4, a flange portion 19 c is provided upward on the outer peripheral edge of the flange shape of the cap 19.

  There is a slight gap between the shaft 13 and the hole 19a of the cap 19, and the lubricating oil in the bearing holder 18 may leak from the gap. However, according to the present embodiment, in addition to the effects of the first embodiment, even when the lubricating oil flows out from the central hole of the cap 19, the upward flange portion 19c is provided on the outer peripheral edge of the flange 19b. Therefore, there is an effect that the lubricating oil can be more reliably prevented from flowing into the rotor 10.

(Third embodiment)
FIG. 5 is a cross-sectional view of the brushless motor 1 according to the present embodiment, and FIG. 6 is a plan view of the washer 24. In FIG. 5, the same components as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the present embodiment, the difference from the first embodiment is that, as shown in FIG. 5, a washer 24 is disposed between the flange 19b and the winding 22, and the washer 24 is a resin shown in FIG. The washer 24 has an outer diameter larger than the inner diameter of the magnet 14 and smaller than the inner diameter of the rotor case 12, and the inner diameter of the washer 24 is slightly larger than the outer diameter of the bearing holder 18. It is possible to move in the axial direction between them and abut against the magnet 14 so as to function as a retainer.

Also in the brushless motor 1 of the present embodiment, a retaining member (washer 24) that restricts the axial movement of the rotor 10 is provided in the space between the inner peripheral surface of the rotor case 12 and the outer peripheral surface of the bearing holder 18. Therefore, the brushless motor 1 can be reduced in thickness and size.
Moreover, since the thing of this embodiment is installed in the state in which the washer 24 is free, assembling is very easy, and when the upper end of the winding 22 is not lower than the upper end of the magnet 14, the winding 22 of the stator core 20 Even if the height varies, it can be attached without adjusting the height of the washer 24, so that variations in the winding 22 can be absorbed.
The washer 24 may be another example as shown in FIG. The washer 24 in FIG. 7 is dish-shaped and has a flange 24a on its outer periphery. The flange 24 a is set to a height that does not contact the magnet 14 even when the upper end of the winding 22 is lower than the upper end of the magnet 14. Therefore, the washer 24 of FIG. 7 is very easy to assemble, and even if the height of the windings 22 of the stator core 20 varies, the variation can be reliably absorbed.

The washer 24 is easy to install in a free state as described above, but may be fixed, for example, as shown in FIGS.
In the configuration shown in FIG. 8, the inner diameter of the washer 24 is designed to be substantially the same as the outer periphery of the bearing holder 18, and the washer 24 is fixed to the outer periphery of the bearing holder 18 at a predetermined height between the flange 19 b and the winding 22. This is an example. FIG. 9 shows an example in which the inner diameter of the washer 24 is designed to be substantially the same as the outer periphery of the bearing holder 18, and the washer 24 is fixed to the lower side of the flange 19 b of the cap 19. FIG. 10 shows an example in which a ring-shaped washer 24 is coaxial with the cap 19 and fixed on the flange 19b.

  8 to 10, when the rotor 10 moves in the axial direction, the washer 24 can abut against the magnet 14 and function as a retaining member. In particular, in the configuration of FIG. 10, even if the lubricating oil leaks from the gap between the shaft 13 and the central hole 19a of the cap 19, a ring-shaped washer 24 forms a step 24b on the flange 19b. Therefore, the lubricating oil can be effectively prevented from flowing into the motor.

Further, the washer 24 is not limited to the form shown in FIG. 6, and for example, those shown in FIGS. 11 to 13 can be used. FIG. 11 shows an example in which one cut is provided in the radial direction, FIG. 12 shows an example in which a part is cut into a C ring, and FIG. 13 shows an example in which a semicircle is cut out at three places on the outer periphery.
By using the washer 24 as shown in FIGS. 11 to 13, it can be easily deformed and easily attached when inserted into the outer periphery of the bearing holder 18. Further, by using the washer 24 having the form as shown in FIG. 13, the elastic deformation of the outer peripheral portion is facilitated, and the assembly of the rotor 10 and the starter 11 is facilitated.

(Fourth embodiment)
FIG. 14 is a cross-sectional view of the brushless motor according to the present embodiment. FIG. 15 is an enlarged perspective view of a main part of FIG. In FIG. 14, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the present embodiment, the difference from the first embodiment is that a locking portion 25 for positioning the magnet 14 protruding radially inward is formed inside the rotor case 12, and this locking portion 25 is When the rotor 10 moves in the axial direction, it contacts the flange 19b of the cap 19 and functions as a retaining member.
That is, the locking portion 25 can pass downward in the axial direction while elastically deforming the flange 19b at the time of motor assembly, and the axial movement of the rotor 10 can be restricted after assembly.

Also in the brushless motor of this embodiment, a retaining member (locking portion 25) that restricts the axial movement of the rotor 10 is provided in the space between the inner peripheral surface of the rotor case 12 and the outer peripheral surface of the bearing holder 18. Therefore, the brushless motor can be reduced in thickness and size.
Moreover, since the locking portion 25 for positioning the magnet 14 also serves as a retaining member, the number of members and the number of assembly steps can be reduced.

(Fifth embodiment)
FIG. 16 is a cross-sectional view of the brushless motor according to the present embodiment. In FIG. 16, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
In this embodiment, the difference from the first embodiment is that the bearing holder 18 is not provided with a cap 19 for preventing oil leakage covering the open end, and a hole of a burring shape 26a is provided at the center on the outer periphery of the bearing holder 18. A resin washer 26 having an inner diameter is fixed, and the outer diameter of the washer 26 is designed to be larger than the inner diameter of the magnet 14 and smaller than the inner diameter of the rotor case 12, and when the rotor 10 moves in the axial direction, the rotor It is a point which contacts the magnet 14 in the case 12 and functions as a retaining member.
That is, the magnet 14 in the rotor case 12 can pass downward in the axial direction while elastically deforming the washer 26 at the time of motor assembly, and the axial movement of the rotor 10 can be restricted after assembly.

  Also in the brushless motor of this embodiment, a retaining member (washer 26) that restricts the axial movement of the rotor 10 is provided in the space between the inner peripheral surface of the rotor case 12 and the outer peripheral surface of the bearing holder 18. Therefore, the brushless motor 1 can be reduced in thickness and size.

(Sixth embodiment)
FIG. 17 is an assembly diagram of the brushless motor 1 according to the present embodiment. FIG. 18 is a cross-sectional view of the brushless motor 1 according to the present embodiment. 17 to 18, the same components as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the present embodiment, the difference from the first embodiment is that, as shown in FIG. 18, the rigid cap 19 having no elasticity is mounted without being fixed to the bearing holder 18, and the rotor 10 without magnets. Is inserted into the stator 11, and after the locking portion 16 of the rotor case 12 passes through the flange 19 b of the cap 19, the magnet 14 is fixed to the rotor case 12. Thereafter, a rod-shaped jig 28 is inserted through a plurality of holes 27 provided in advance on the bottom surface of the rotor case 12 and the cap 19 is pressed against the bearing holder 18 to be fixed by press-fitting or an adhesive.
That is, after the motor is assembled, the cap 19 abuts against the magnet 14 with respect to the movement of the rotor 10 in the axial direction, thereby functioning as an axial stopper.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these form examples, A suitable change is possible within the range of the summary of this invention.

For example, although the washer described above is made of resin, a thin elastic metal plate may be used.
Further, although the outer shape of the flange 19b of the cap 19 described above is circular, any shape that restricts the movement of the rotor as an axial retaining mechanism of the rotor 10 may be used. FIG. 19 shows another example of a cap 29, which is a claw portion 29 a, which has three claw portions on the outer periphery of the flange and is larger than the inner diameter of the magnet 14 and smaller than the inner diameter of the rotor case 12. The magnet 14 can be passed downward in the axial direction when the motor is assembled. After the assembly, the movement of the rotor 10 in the axial direction can be restricted.

It is sectional drawing of the brushless motor concerning the 1st Embodiment of this invention. 1 is an assembly diagram of a brushless motor according to a first embodiment of the present invention. It is a perspective view of a cap. It is sectional drawing of the brushless motor concerning the 2nd Embodiment of this invention. It is sectional drawing of the brushless motor concerning the 3rd Embodiment of this invention. It is a top view of a washer. It is a 1st modification of the brushless motor concerning the 3rd Embodiment of this invention. It is a 2nd modification of the brushless motor concerning the 3rd Embodiment of this invention. It is a 3rd modification of the brushless motor concerning the 3rd Embodiment of this invention. It is a 4th modification of the brushless motor concerning the 3rd Embodiment of this invention. It is a 1st modification of a washer. It is a 2nd modification of a washer. It is a 3rd modification of a washer. It is sectional drawing of the brushless motor concerning the 4th Embodiment of this invention. It is an expansion perspective view of the principal part of FIG. It is sectional drawing of the brushless motor concerning the 5th Embodiment of this invention. It is an assembly drawing of the brushless motor concerning the 6th Embodiment of this invention. It is sectional drawing of the brushless motor concerning the 6th Embodiment of this invention. It is a modification of a cap.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless motor 10 Rotor 11 Stator 12 Rotor case 13 Shaft 14 Magnet 15 Step part 16 Locking part 17 Bearing 18 Bearing holder 19 Cap 19a Hole 19b Flange 19c Eave part 20 Stator core 21 Stator base 22 Winding 23 Substrate 24 Washer 24a Flange 24 Step 25 Locking part 26 Washer 26a Burring 27 hole 28 Jig 29 Cap 29a Claw part 29b Hole

Claims (2)

A rotor case, a shaft fixed to the center of the rotor case, and a rotor having a cylindrical magnet fixed to the inner peripheral surface of the rotor case;
A brushless motor comprising: a bearing that rotatably supports the shaft; a bottomed cylindrical bearing holder that fixes the bearing; and a stator that has a stator core that is disposed opposite to the magnet and wound.
The bearing holder is provided with a cap for preventing oil leakage covering the open end,
The cap has a hole through which the shaft passes, has a bottomed cylindrical shape, and has a flange on the periphery of the open end,
A washer is disposed between the flange and the winding;
An inner diameter of the washer is formed slightly larger than an outer diameter of the bearing holder, and the washer is movable in an axial direction between the flange and the winding;
The washer functions as a retaining member that contacts the magnet and restricts the axial movement of the rotor when the rotor moves in the axial direction . The brushless motor according to claim 1, wherein the washer has a shape in which a semicircle is cut out on an outer periphery.

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