JP2986686B2 - Brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor which is effective for a flat and small brushless motor, and which is particularly suitable for a motor requiring high rotational accuracy, such as a floppy disk drive motor.

[0002]

2. Description of the Related Art As a thrust bearing structure of a brushless motor, there is one described in Japanese Patent Application Laid-Open No. 4-95609. FIG.
FIG. 1 shows such a conventional brushless motor. A substantially cylindrical sintered oil-impregnated bearing 2 is provided in a central hole of a substrate 1.
Is press-fitted and fixed. An annular race 13 is fixed to the outer peripheral portion of the sintered oil-impregnated bearing 2 on the substrate 1, and rolling elements 16 are arranged on the race 13, and the rolling elements 16, A thrust bearing is constituted by the wheel 13. Further, a plurality of air core coils 7 are provided on the outer peripheral portion of the substrate 1, and an FG coil 14 is provided on the outer peripheral portion of the air core coil 7.

A shaft 3 is inserted through the sintered oil-impregnated bearing 2 and is slidably supported. A rotor case 6 is integrally fixed to the tip of the shaft 3 via a hub 4. An annular chucking magnet 9 is fixed to the outer upper surface of the hub base 4, and a driving pin 8 is provided on the outer peripheral side of the rotor case with respect to the chucking magnet 9. The drive pin 8 is supported while being urged upward by an urging spring 17 attached to the bottom side of the rotor case 6. On the other hand, a flat annular driving magnet 5 is arranged on the outer peripheral portion of the bottom surface of the rotor case 6 so as to face the upper surface of the air core coil 7 at an appropriate interval. Further, an FG magnet 15 is fixed to the outer peripheral bottom surface of the rotor case 6 with respect to the drive magnet 5.
It faces the FG coil 14 at an appropriate interval.
The shaft 3, the hub 4 and the rotor case 6 constitute a motor rotor set 10.

An annular race 13 is fixed to the center of the substrate 1 and to the outer periphery of the sintered oil-impregnated bearing 2, and a rolling element 16 shown in FIG. Are in sliding contact with each other. In FIG. 11, a rolling element 16 is composed of a plurality of steel balls 11 and a retainer 12 for holding the steel balls 11 at regular intervals in a circumferential direction. The sintered oil-impregnated bearing 2 and the rolling element 16 partially overlap in the axial direction when viewed from the side. Also,
A plurality of holding holes 12a for holding the steel balls 11 are formed on the outer periphery of the center hole of the holder 12, and the steel balls 11 are slidably held in the holding holes 12a. The lower end of the steel ball 11 is in sliding contact with the upper surface of the bearing ring 13, and the upper end of the steel ball 11 is in sliding contact with the lower surface of the biasing spring 17 attached to the bottom surface of the rotor case. And a thrust bearing to be supported.

[0005]

In the brushless motor as described above, especially for a floppy disk drive, it is necessary to reduce the size of the brushless motor due to its characteristics. desired.

On the other hand, in a motor for driving a floppy disk or the like, while miniaturizing the motor, extremely high-precision rotation is required to prevent a tracking error or the like. Therefore, if the motor is reduced in size and flat,
It is said that the shaft causes so-called rubbing motion, which tends to cause rotational blurring, so that high rotational accuracy cannot be obtained. Conversely, if the bearing portion is enlarged to obtain high rotational accuracy, the motor cannot be downsized and flat. There was an inconvenience. In order to solve such a problem, the rolling element 16 as a thrust bearing and the sintered oil-impregnated bearing 2 as a radial bearing are arranged so as to partially overlap in the axial direction when viewed from the side, as in the above-described conventional example. Had been proposed.

SUMMARY OF THE INVENTION The present invention has been made to further improve the prior art, and provides a brushless motor in which the flatness of the brushless motor can be reduced and the rotational accuracy of the motor can be improved. The purpose is to:

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention not only arranges a radial bearing and a thrust bearing so as to partially overlap with each other, but also forms a hub base which is originally dead space. Based on the idea of effectively utilizing the recess to reduce the size of the motor in a flat shape, at least a part of the thrust bearing is housed in a recess formed in the hub base.

[0009] More specifically, a hub is provided for rotating a disk mounted thereon, a rotor case mounted with a drive magnet and rotating integrally with the hub, and a shaft fixed to the center of the hub. A rotor set, a radial bearing rotatably supporting the shaft in a radial direction, a thrust bearing having a rolling element and a bearing ring comprising a steel ball and a retainer and supporting a load in the thrust direction of the rotor set; In the brushless motor comprising: the rolling element is at least partially housed in a recess formed in the hub base,
The bearing ring is held in contact with the axial end face of the radial bearing, and the steel ball contacts the recess of the hub and the bearing ring. A side wall may be formed on the outer peripheral side of the bearing ring, and the position of the rolling element may be regulated by the inner peripheral surface of the side wall, or the position of the rolling element may be regulated by the inner peripheral surface of the concave portion of the hub base. Good. Further, an uneven portion may be formed on the race ring, and the position of the rolling element may be regulated by the uneven portion.

[0010]

Since at least a part of the rolling element is housed in the recess formed in the hub base, the motor can be reduced in flatness and size. In addition, by regulating the position of the rolling element by the side wall of the bearing ring or the inner peripheral surface of the concave portion of the hub stand, it is possible to improve the rotational accuracy of the motor. Thus, even if the position of the rolling element is regulated, the rotation accuracy can be improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a brushless motor according to the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show an embodiment in which the brushless motor according to the present invention is applied to a motor for driving a floppy disk. 1 and 2
In the figure, a central hole 21a is formed in a central portion of the substrate 21, and a sintered oil-impregnated bearing 22 is inserted and assembled into the central hole 21a. The sintered oil-impregnated bearing 22 has a cylindrical portion 22.
b and a flange portion 22a, and a central hole of the stator core 27 is fitted to an outer peripheral step portion of the flange portion 22a. The stator core 27 is fixed on the substrate 21 by screws 39, whereby the sintered oil-impregnated bearing 22 is also fixed to the substrate 21. The stator core 27 has a plurality of salient poles extending radially from the center toward the outer periphery, and a driving coil 37 is wound around each salient pole. The drive coil 37 is electrically connected to a control unit formed on the substrate 21, and is controlled to be energized by the control unit.

A shaft 23 is inserted through a center hole of the sintered oil-impregnated bearing 22 and is rotatable. Shaft 2
A hub table 24 on which a disk is placed is fixed to the upper end of 3, and rotates integrally with the shaft 23. The hub stand 24 has a disk mounting portion 24a and a flange portion 24b.
The disk mounting portion 24a is provided with a flange portion 24b.
It is formed so as to be located axially above. Thus, a step is formed between the disk mounting portion 24a and the flange portion 24b, and a concave portion 24c is formed on the bottom surface of the hub stand 24. The disk mounting part 24a
A central hole of a substantially cup-shaped rotor case 25 is fitted and fixed to a step portion between the rotor case 25 and the flange portion 24b so that the rotor case 25 rotates integrally with the shaft 23 via the hub stand 24. It has become. A drive pin 28 is provided at the center of the rotor case 25, and the drive pin 28 is engaged with an engagement hole of the disk to rotate the disk. At the center of the upper surface of the rotor case 25, a ring-shaped chucking magnet 29 is fixed along the outer periphery of the disk mounting portion 24a of the hub stand, and the chucking of the disk is performed by the chucking magnet 29. It has become.

A ring-shaped driving magnet 26 is fixed to the inner peripheral surface of the peripheral wall of the rotor case 25.
The drive magnet 26 is magnetized at regular intervals in the circumferential direction, and N poles and S poles are formed alternately. The inner peripheral surface of the drive magnet 26 faces the outer peripheral surface of the stator core 27 at an appropriate interval. doing. Further, a flange portion is formed from the peripheral wall of the rotor case 25 toward the outer peripheral direction, and a ring-shaped frequency generating magnet 34 is fixed to the bottom surface of the flange portion. The frequency power generation magnet 34 faces a magnetic detection element on the substrate 21 (not shown). A rotor set 30 is configured by the hub stand 24, the rotor case 25, the shaft 23, and the like. The rotor is biased by controlling the energization of the drive coil 37 based on a signal from the magnetic detection element. It is designed to rotate.

A central hole of a cup-shaped race ring 33 is fitted to the upper end of the cylindrical portion 22b of the sintered oil-impregnated bearing 22, and the upper end surface of the flange 22a of the sintered oil-impregnated bearing 22 is fitted. Held in contact. A steel ball 31 and a retainer 32 are provided in the inner peripheral portion of the bearing ring 33 and in the concave portion 24c on the bottom surface of the hub base.
Are accommodated so as to be movable in the circumferential direction. The retainer 32 has a disk shape, and is provided with an appropriate number of notches cut out in an arc shape from the outer peripheral side toward the center of rotation over the entire circumference. 31 is rotatably held. The steel balls 31 have end faces protruding from the upper and lower surfaces of the retainer 32, respectively. The upper end of the protruding steel ball 31 contacts the recess 24 c of the hub stand, and the lower end of the steel ball 31 contacts the upper surface of the bearing ring 33. The outer end surface of the steel ball 31 also protrudes from the notch of the retainer 32, and the position of the protruding end surface is regulated by contacting the inner peripheral surface of the side wall 33 a of the bearing ring 33. And the steel ball 31
And a cage 32, and a rolling element 36,
Thus, a thrust bearing for supporting the load in the thrust direction of the rotor set 30 is configured.

In the brushless motor constructed as described above, the rolling element 36 is formed of the sintered oil-impregnated bearing 2 when viewed from the side.
Not only is it arranged to overlap with 2 in the axial direction,
Since the upper portion of the rolling element 36 is housed in the recess 24c of the hub base, which is essentially a dead space, the thickness of the motor can be further reduced, and a flat and small motor can be obtained. Further, since at least a part of the rolling element 36 is housed in the recess 24c of the hub base, the recess 24c of the hub base also serves as the upper race.
There is no need to separately provide an upper race, and the number of parts can be reduced, so that assembly becomes easier and manufacturing costs can be reduced. Furthermore, steel ball 31
Is in direct contact with the recess 24c of the hub base, so that the hub base 24 and the steel balls 3
1 and the assembling accuracy such as the deflection of the hub stand 24 can be improved.

When the steel ball 31 rotates, the retainer 32
The position of the inner circumferential side is regulated by the
Since the position is regulated by a, the steel ball 31 does not deviate from the predetermined sliding trajectory, and the rotation accuracy of the motor can be improved.

Further, since the raceway ring 33 is provided with the side wall 33a, it is possible to prevent the lubricating oil from seeping from the sintered oil-impregnated bearing 22 from scattering.

Next, various modified embodiments of the brushless motor according to the present invention will be described. The same components as those of the embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 3, a cup-shaped race ring 5 is provided on a cylindrical portion 22b of a substantially cylindrical sintered oil-impregnated bearing 22.
5 is assembled and held. A rolling element 36 composed of a steel ball 31 and a retainer 32 is mounted on the bearing ring 55 so as to be movable in the circumferential direction. The rolling element 36 is the same as that of the embodiment shown in FIGS. 1 and 2, and is housed in a recess 54c on the bottom surface of the hub base 54. Rolling element 3
The steel ball 31 of No. 6 has a recess 54 on the bottom surface of the hub base.
c, and its lower end is in contact with the upper surface of the bearing ring 55. The outer peripheral end of the steel ball 31 is in contact with the side surface of the recess 54c of the hub base. Thus, the steel ball 31
Is restricted in position by contacting the inner peripheral side surface of the concave portion 54c.

As described above, also in the embodiment shown in FIG. 3, the upper end portion of the rolling element 36 is housed in the concave portion 54c on the bottom surface of the hub and the position is regulated by the inner peripheral side surface of the concave portion 54c. The same effects as those of the embodiment shown in FIGS. 1 and 2 can be obtained.

Next, another embodiment shown in FIG. 4 will be described. In FIG. 4, the hub base 44 has a disk hub mounting portion and a flange portion, and the disk hub mounting portion protrudes axially upward from the flange portion, so that the hub base 44 has a bottom surface. A recess 44c is formed. This recess 44c
A rolling element 46 is housed therein. The rolling element 46 includes a steel ball 41 and a retainer 42, and the steel ball 41 is slidably supported by the retainer 42. The rolling elements 46 are the same as the rolling elements of the conventional example shown in FIG. 11, and an appropriate number of holes for holding the steel balls 41 are formed on the outer peripheral portion of the retainer 42 formed in an annular shape. The steel ball 41
Are rotatably held.

The upper end of the steel ball 41 is formed in the recess 4 of the hub base.
4c, the lower end of the steel ball 41 is in contact with the upper surface of the bearing ring 43. The race 43 is provided with the sintered oil-impregnated bearing 22.
Is held at the upper surface of the sintered oil-impregnated bearing 22 by being in contact with the upper surface of the flange of the sintered oil-impregnated bearing 22. The upper surface of the bearing ring 43 is formed such that a surface on the inner peripheral side of the contact portion with the steel ball 41 is higher than a surface on the outer side in the rotation direction, and thereby the convex portion 4 is formed on the inner peripheral portion of the bearing ring 43.
3a is formed over the entire circumference. The step between the convex portion 43a and the outer peripheral portion of the bearing ring is formed in an arc shape according to the outer peripheral shape of the steel ball 41, and the rolling position of the steel ball 41 is regulated by the convex portion 43a. .

As described above, according to the embodiment shown in FIG. 4, the upper end portion of the rolling element 46 is housed in the recess 44c of the hub base 44, similarly to the embodiment shown in FIGS. Therefore, the thickness of the motor can be reduced. In addition, since the steel ball 41 directly contacts the recess 41c of the hub base, no additional intervening member is required, and the assembling is facilitated, so that not only the cost can be reduced but also the assembling accuracy is improved. Can also be planned. Further, FIG.
According to the embodiment shown in (1), since the steel ball 41 rotates while being positioned by the convex portion 43a, the rotation accuracy can be further improved.

Next, another embodiment shown in FIG. 5 will be described. The same components as those of the embodiment shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. The embodiment shown in FIG. 5 is different from the embodiment shown in FIG. 4 in that a convex portion 53a is provided on the outer peripheral side of the race 53, and the position of the steel ball 41 is regulated by the convex portion 53a. The configuration is the same as that of the embodiment shown in FIG.

As described above, according to the embodiment shown in FIG. 5, since at least a part of the rolling element 46 is housed in the recess 44c of the hub base, the same effect as that of the embodiment shown in FIG. be able to. In addition, the steel ball 41 has the convex portion 5
3a, the position is regulated by this.
The same effects as the embodiment shown in FIG.

Next, another embodiment shown in FIG. 6 will be described. The same components as those in the embodiment shown in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 6, an inner peripheral portion 63b and an outer peripheral portion 63c are formed at an upper end portion of the annular race 63, and the outer peripheral portion 63c protrudes higher than the inner peripheral portion 63b in the axial direction and is higher. A concave portion 63a is formed in the outer peripheral portion 63c, and the concave portion 63a has a deepest portion of the concave portion, that is, a surface with which the lower end portion of the steel ball 41 abuts has substantially the same height as the upper surface of the inner peripheral portion 63b. It is formed so that it becomes.

As described above, also in the embodiment shown in FIG. 6, since the upper end portion of the rolling element 46 is housed in the recess 44c of the hub base, the same effect as that of the embodiment shown in FIGS. Can be played. Further, since the position of the steel ball 41 is regulated by the concave portion 63a, the same effect as in the embodiment shown in FIG.
The concave portion 63a is formed so that the deepest portion of the concave portion, that is, the height of the surface with which the lower end portion of the steel ball 41 abuts is substantially the same as the upper surface of the inner peripheral portion 63b. Even if 41 is incorporated, the thickness of the motor does not increase.

Next, another embodiment shown in FIG. 7 will be described. The embodiment shown in FIG. 7 is an example in which the present invention is applied to a brushless motor in which a hub base and a rotor case are integrated, and an integrally formed member 74 of the hub base and the rotor case is provided at the upper end of the shaft 23. It is fixed and rotates integrally with the shaft 23. The integrally formed member 74 includes a hub base 74a and a rotor case 74b. The hub base portion 74a protrudes axially above the upper surface of the rotor case portion 74b.
A concave portion 74c is formed on the bottom side of 4. Recess 74
The rolling element 36 is accommodated in c, thereby constituting a thrust bearing of the rotor set 70.

As described above, also in the embodiment shown in FIG. 7, since the rolling element 36 is housed in the concave portion 74c formed on the bottom surface of the hub base 74a, the embodiment shown in FIGS. Similar effects can be obtained.

Next, another embodiment shown in FIG. 8 will be described. The same components as those in the embodiment shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 8, a central hole 85a is formed in the center of the substrate 85. The inner peripheral surface of the central hole 85a is formed in a conical shape whose diameter decreases upward in the axial direction. The lower end of the sintered oil-impregnated bearing 82 is inserted into the conical center hole 85a. The sintered oil-impregnated bearing 82 includes a cylindrical portion and a flange portion 82a, and a ridge 82b protruding downward in the axial direction is formed at a lower end portion of the flange portion 82a. And this jetty 8
By caulking 2b along the inner periphery of the central hole 85a, the sintered oil-impregnated bearing 82 is fixed to the substrate 85. An annular bearing ring 83 is inserted into the cylindrical portion of the sintered oil-impregnated bearing 82, and is disposed on the flange portion 82a. The upper surface of the bearing ring 83 is formed in a flat plate shape.
The rolling element 46 is in contact with the upper surface of the roller 3. The rolling element 46 is housed in a recess 44c of the hub base 44, and the rolling element 4
6 and the hub base 44 are the same as those in the embodiment shown in FIG.

As described above, also in the embodiment shown in FIG.
Since the upper end portion of the rolling element 46 is housed in the concave portion 44c of the hub base, and the position of the rolling element is regulated by the concave portion 44c, the same effect as the embodiment shown in FIG. Can be. Further, since the sintered oil-impregnated bearing 82 is fixed to the substrate 85 by caulking the jetty 82b, the fixing strength and the positional accuracy of the sintered oil-impregnated bearing 82 can be improved, and the rotation of the motor can be further improved. Accuracy can be improved.

Next, the embodiment shown in FIG. 9 will be described. The embodiment shown in FIG. 9 is an example in which the present invention is applied to a surface facing motor. In FIG. 9, a central hole is formed in the central portion of the substrate 91, and the lower end of the sintered oil-impregnated bearing 92 is inserted into the central hole. The sintered oil-impregnated bearing 92 includes a cylindrical portion and a flange portion, and a substantially annular race ring 103 is inserted into the cylindrical portion above the flange portion. The bearing ring 103 includes a contact portion with the steel ball 101 described later and a mounting portion, and the contact portion protrudes axially above the mounting portion. The contact portion of the bearing ring 103 is disposed on the flange of the sintered oil-impregnated bearing 92, and the mounting portion is disposed on the substrate 91. By attaching the mounting portion of the bearing ring 103 to the substrate 91 with a screw, the bearing ring 103 and the sintered oil-impregnated bearing 92 are fixed. An air-core coil 97 is provided around the shaft
Are appropriately arranged on an arc centered on the
It is electrically connected to the control unit formed above and is controlled to be energized.

A shaft 93 is inserted through a center hole of the sintered oil-impregnated bearing 92, and is rotatably supported.
A hub base 94 is fixed to the upper end of the shaft 93 so as to rotate integrally with the shaft 93.
The hub base 94 includes a disk hub mounting portion and a flange portion, and the disk hub mounting portion projects axially upward from the flange portion to form a stepped portion. A recess 94c is formed. A center hole of a substantially cup-shaped rotor case 95 is fitted and fixed to the step portion of the hub base 94. A drive pin 98 is provided at the center of the rotor case 95, and a ring-shaped chucking magnet 99 is fixed thereto. On the other hand, a drive magnet 96 is fixed to the bottom surface of the rotor case 95 at a position facing the upper surface of the air core coil 97 at an appropriate distance. A flange portion is formed from the peripheral wall of the rotor case 95 toward the outer peripheral direction. A magnet 104 for frequency generation is attached to the bottom surface of the flange portion. At the same time.

A rolling element 106 is accommodated in a concave portion on the bottom side of the hub base 94. The rolling conductor 106 comprises a steel ball 101 and a retainer 102. The rolling element 106 has the same configuration as that of the embodiment shown in FIG.

In the surface-facing type motor shown in FIG. 9 as described above, the rolling elements 106 are not only arranged so as to overlap the sintered oil-impregnated bearing 92 in the axial direction, but also viewed from the side. Since the upper portion of the housing 106 is housed in the recess 94c of the hub base, which is essentially a dead space,
The thickness of the motor can be further reduced, and a flat and small motor can be obtained. Further, since at least a part of the rolling element 106 is housed in the recess of the hub stand, and the recess of the hub stand also serves as the upper race, it is not necessary to separately provide an upper race. Can be reduced, the assembling becomes easy, and the manufacturing cost can be reduced. Further, since the steel ball 101 is in direct contact with the recess of the hub base, assembling of the right angle accuracy between the hub base 94 and the steel ball 101 and the deflection of the hub base 94 as compared with the case where an intermediate part is interposed. Accuracy can be improved.

The configuration of the rolling elements and races as shown in FIGS. 1 to 8 may be applied to the surface-facing type motor shown in FIG. Similar effects can be obtained. .

In the embodiment shown in FIGS. 1 to 9, resin coating or plating may be applied to the upper surface of the hub base, that is, the mounting surface of the disk hub, so that the contact surface with the disk hub is smooth. And the sliding characteristics can be improved. In addition, the surface may be hardened by plating the contact surface with the steel ball, such as the bottom surface of the hub stand and the upper surface of the bearing ring, so that the life of the thrust bearing can be improved.

[0037]

According to the present invention, at least a part of the rolling element is housed in the recess formed in the hub base, the race is held in contact with the axial end face of the radial bearing, and the steel ball is held. Is in contact with the recess of the hub base and the raceway,
At least a part of the rolling elements is housed in the concave portion of the hub base, which is essentially a dead space, so that the thickness of the motor can be further reduced and the flatness of the motor can be reduced. Further, since at least a part of the rolling element is housed in the recess of the hub base, and the recess of the hub base also serves as the upper race, the number of parts can be reduced, and assembly is easy. Thus, the manufacturing cost can be reduced. Furthermore, since the steel ball directly contacts the recess of the hub base, the accuracy of the right angle between the hub base and the steel ball and the assembling accuracy of the hub base, such as deflection, should be improved as compared with the case where an intermediate part is interposed. Can be.

As described in the second aspect of the present invention, since the side wall is provided on the outer peripheral side of the bearing ring and the position of the rolling element is regulated by the inner peripheral surface of the side wall, the rotational accuracy of the motor can be improved. .

Further, the rotational accuracy of the motor can be improved by regulating the position of the rolling element on the inner peripheral surface of the concave portion of the hub base as in the third aspect of the present invention.

Further, the rotation accuracy of the motor can be improved by forming an uneven portion on the raceway and regulating the position of the rolling element by the uneven portion as in the invention of the fourth aspect. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a brushless motor according to the present invention.

FIG. 2 is an exploded side view of the embodiment.

FIG. 3 is a sectional view of a main part showing another embodiment according to the present invention.

FIG. 4 is a sectional view of a main part showing another embodiment according to the present invention.

FIG. 5 is a sectional view of a main part showing another embodiment according to the present invention.

FIG. 6 is a sectional view of a main part showing another embodiment according to the present invention.

FIG. 7 is a sectional view of a main part showing another embodiment according to the present invention.

FIG. 8 is a sectional view of a main part showing another embodiment according to the present invention.

FIG. 9 is a sectional view showing another embodiment according to the present invention.

FIG. 10 is a sectional view showing an example of a conventional brushless motor.

FIG. 11 is a plan view showing a rolling element of the conventional example.

[Explanation of symbols]

 22 Sintered oil-impregnated bearing as radial bearing 23 Shaft 24 Hub stand 24c Concave portion 25 Rotor case 26 Drive magnet 30 Rotor set 31 Steel ball 32 Cage 33 Track ring 33a Side wall 36 Rolling element 41 Steel ball 42 Cage 43 Track ring 43a Convex Part 44 hub mount 44c concave portion 46 rolling element 53 raceway ring 53a convex portion 54 hub mount 54c concave portion 63 raceway ring 63a concave portion 74 hub mount 74c concave portion 92 sintered oil-impregnated bearing 94 hub mount 101 steel ball 102 retainer 106 rolling element

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02K 29/00 F16C 33/10 H02K 5/16 H02K 5/173

Claims (4)

(57) [Claims] 1. A hub assembly for mounting and rotating a disk thereon, a rotor case mounted with a drive magnet and rotating integrally with the hub mount, and a rotor set having a shaft fixed to the center of the hub mount. A radial bearing rotatably supporting the shaft in the radial direction; and a thrust bearing having a rolling element including a steel ball and a retainer and a bearing ring, and supporting a load in the thrust direction of the rotor set. In the brushless motor, at least a part of the rolling element is housed in a recess formed in the hub base, the race is held in contact with an axial end face of the radial bearing, and the steel ball is a hub. A brushless motor, wherein the brushless motor is in contact with a recess of a base and a race. 2. The brushless motor according to claim 1, wherein the bearing ring has a side wall on an outer peripheral side, and a position of a rolling element is regulated on an inner peripheral surface of the side wall. 3. The brushless motor according to claim 1, wherein the position of the rolling element is regulated on the inner peripheral surface of the concave portion of the hub base. 4. The brushless motor according to claim 1, wherein an uneven portion is formed on the bearing ring, and the position of the rolling element is regulated by the uneven portion.