JPH04289749A - Motor - Google Patents

Abstract

PURPOSE:To sufficiently hold a suitable prepressure state of a plurality of rows of radial ball bearings by providing an adhesive reserving gap including a part crossing with a boundary between an outer race and an outer race support at least in a load direction line of each row of rolling spheres on the entire periphery of the boundary. CONSTITUTION:A stress tending to externally expand at parts in which load direction lines 54 and 56 of rolling spheres of rolling sphere rows 38 and 40 are passed, is operated at an outer race 36 of this spindle motor. However, since parts in which the lines 54 and 56 cross a boundary between an outer race 36 and a cylindrical support 12, include outer peripheral adhesive reserving grooves 42, a deformation of the race 36 due to the stress is allowed in a certain degree. Thus, adverse influence to a prepressure state such as collapses of a prepressure balance over an entire periphery, a prepressure balance between the rows 38 and 40 due to a state of accuracy, etc., of parts of the support 12, a hollow rotary shaft 34 and a plurality of rows of radial ball bearings 35 associated therebetween, thermal expansions, etc., is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor equipped with a double row radial ball bearing with fixed position preload.

0002

2. Description of the Related Art In order to reduce the wobbling of the rotational axis of a motor as much as possible, it is necessary to apply preload to the ball bearings used to remove play in the raceway of the rolling balls. In this sense, double-row ball bearings, in which fixed-position preload is applied through the interaction of both rows of rolling balls, are conveniently used in motors because no special work is required to apply preload.

0003

[Problem to be Solved by the Invention] However, the outer ring of such a double-row ball bearing is subjected to stress that tends to bulge outward around the area through which the load direction line of each row of rolling balls passes. However, since the outer ring is integral with each row of rolling balls, the preload balance over the entire circumference or between both rows of rolling balls may be disrupted due to assembly accuracy, thermal expansion, etc. An adverse effect on the condition could occur, which could lead to an unacceptable runout of the axis of rotation and noise, as well as a deterioration in rotation accuracy and bearing life.

The present invention has been made in view of the above-mentioned problems existing in the prior art, and its purpose is to sufficiently maintain an appropriate preload state of a double row radial ball bearing. Our goal is to provide you with a motor that you can use.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the motor of the present invention is a double-row radial motor that is preloaded in a fixed position by the interaction of both rows of rolling balls having contact angles opposite to each other. The ball bearing includes an outer ring support portion whose inner circumference side is bonded to the outer circumference side of the outer ring of the double-row radial ball bearing, and at least one of the rolling balls of each row is provided at the boundary between the outer ring and the outer ring support portion. An adhesive reservoir gap including a portion where the load direction line intersects with the boundary portion is provided all around the circumference.

[0006]

[Operation] The adhesive that accumulates in the adhesive reservoir gap ensures that the outer ring of the double row radial ball bearing is securely fixed to the outer ring support portion.

On the other hand, stress acts on the outer ring that tends to bulge outward centering on the area where the load direction lines of the rolling balls in each row pass, so that at the boundary between the outer ring and the outer ring support, By providing an adhesive pool gap around the entire circumference, including at least the portion where the load direction line of each row of rolling balls intersects with the boundary, the outer ring support and inner ring support and the accuracy of each part of the double-row radial ball bearing assembled between them, as well as the preload balance over the entire circumference and between both rows of rolling balls may be disrupted due to thermal expansion, etc., which may adversely affect the preload condition. is prevented from occurring.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described with reference to the drawings. 1 to 3 relate to a brushless spindle motor for driving a hard disk as an embodiment of the present invention, of which FIG. 1 is a cross-sectional view of a completed state, and FIG.
and FIG. 3 is a sectional view of main parts showing an assembled state.

[0009] 10 is a fixed bracket. A cylindrical support part 12 (outer ring support part) is provided on one side of the fixed bracket 10.
The annular portion between the cylindrical support portion 12 and the brim portion 14 is formed into a recess 16, and the inside of the cylindrical support portion 12 is a penetrating portion.

A stator core 18 is fixed to the outer peripheral side of the cylindrical support portion 12, and a stator coil 20 is wound around the stator core 18. Reference numeral 22 denotes a lead wire of the stator coil 20, which is led out to the outside of the motor through a through hole 24 provided in the recess 16 of the fixed bracket 10. 26 is a sealing material that seals the through hole.

Reference numeral 28 denotes a cup-shaped rotor hub to which a hard disk is fitted and fixed. An annular rotor magnet 32 is fixed inside an outer peripheral wall 30 of the rotor hub 28 . 34 is a hollow rotating shaft that projects inside the cup at the center of the cup-shaped rotor hub 28.

35 is a double row radial ball bearing. The outer ring 36 of this double row radial ball bearing 35 is connected to the fixed bracket 1
The inner ring 37 is adhesively fixed to the inner peripheral side of the cylindrical support part 12 of
is adhesively fixed to the outer peripheral side of the hollow rotating shaft 34 of the rotor hub 28. Through this double row radial ball bearing 35,
The rotor hub 28 is rotatably supported by the fixed bracket 10.

38 is an upper rolling ball row, and 40 is a lower rolling ball row. Reference numeral 42 denotes an annular outer adhesive reservoir groove provided all around the inner circumference of the cylindrical support portion 12, and 44 denotes an annular outer adhesive reservoir groove provided all the way around the inner circumference of the inner ring 37 of the double-row radial ball bearing 35. This is an annular inner circumferential adhesive reservoir groove provided over the entire length. Both axially outer ends of the inner circumferential adhesive reservoir groove 44 are connected to both rolling ball rows 3
The positions in the axial direction of the inner ends of Nos. 8 and 40 approximately coincide with each other.

The vertically rolling ball rows 38 and 40 are approximately 20°
have opposite contact angles. The diameter of the rolling balls in the vertical rolling ball rows 38 and 40 and the outer ring 36
The distance between the upper and lower raceway grooves 46 and 48 and the inner ring 37
A fixed position preload is applied by setting the relationship between the distance between the upper and lower raceway grooves 50 and 52 so that the upper and lower rolling ball rows 38 and 40 both receive some pressure due to their interaction.

54 and 56 are the rolling ball rows 38 and 40, respectively.
is the load direction line of the rolling ball. Both load direction lines 54
and 56 intersect with the boundary between the outer ring 36 and the cylindrical support portion 12, respectively, in such a positional relationship that one outer circumferential adhesive reservoir groove 42 includes the portions thereof. In this embodiment, the load direction lines 54 and 56 intersect on the outer circumferential side of the double row radial ball bearing 35, but of course they may intersect on the inner circumferential side. 58 is an airtight rubber ball fitted into the hollow hole of the hollow rotating shaft 34.

[0016] This spindle motor can be assembled, for example, as follows. As shown in FIG. 2, a relatively high viscosity adhesive 60 that does not easily drip is applied to the inner circumferential surface of the upper end of the cylindrical support part 12 over the entire circumference, and then a comparative An adhesive 62 with low target viscosity is applied over the entire circumference. Then, the relatively high viscosity adhesive 60 on the lower side can prevent the relatively low viscosity adhesive 62 applied on the upper side from dripping. Note that these adhesives 60 and 62 may be applied at the same time.

After coating, double row radial ball bearing 35 is inspected from above.
Insert. Then, the upper and lower adhesives 60 and 62 mix and spread between the inner peripheral surface of the cylindrical support part 12 and the outer peripheral surface of the outer ring 36, and the adhesive accumulates in the outer peripheral adhesive reservoir groove 42. Become. At this time, since the adhesive 62 with relatively low viscosity is mixed with the adhesive 60 with relatively high viscosity, the fluidity is relatively increased as a whole, and the adhesive is spread uniformly and inside the outer adhesive reservoir groove 42. Since the adhesive will accumulate in the area, the reliability of adhesive fixation will be increased. Also extra adhesive 6
4 accumulates at the lower end of the outer ring 36 as shown in FIG. 3, so there is no risk of it adhering to the rotor hub 28. Note that the adhesive used here is one that cures both the adhesive that spreads between the inner circumferential surface of the cylindrical support portion 12 and the outer circumferential surface of the outer ring 36 and the adhesive that protrudes from the lower end of the outer ring 36. It requires that. Therefore, for example, a material having both anaerobic properties and ultraviolet curing properties can be used. However, it goes without saying that the mixture of both adhesives must not cause any kind of reaction that would significantly reduce fluidity.

Next, as shown in FIG. 3, a relatively high viscosity adhesive 60 that does not easily drip is applied to the inner peripheral surface of the upper end of the inner ring 37, and then the upper side of the adhesive 60 is applied. After applying a relatively low viscosity adhesive 62 all around the circumference, the hollow rotating shaft 34 of the rotor hub 28 is fitted from above. Then, the upper and lower adhesives 60 and 62 mix and spread between the inner circumferential surface of the inner ring 37 and the outer circumferential surface of the hollow rotary shaft 34, and the adhesive accumulates in the inner circumferential adhesive reservoir groove 44, resulting in the adhesion. Fixation becomes more reliable. Also extra adhesive 6
6 accumulates between the lower end of the hollow rotating shaft 34 and the inner circumference of the inner ring 37 as shown in FIG. 1, so there is no risk of it adhering to the rotor hub 28.

A stress that tends to bulge outward is applied to the outer ring 36 of this spindle motor, centering on the portion through which the load direction lines 54 and 56 of the rolling balls of each row of rolling balls 38 and 40 pass. However, since the outer circumferential adhesive reservoir groove 42 includes the portions where both load direction lines 54 and 56 intersect with the boundary between the outer ring 36 and the cylindrical support portion 12, the outer ring 36 due to stress etc. Deformation is allowed to some extent,
As a result, the precision of each part of the cylindrical support part 12, the hollow rotating shaft 34, and the double row radial ball bearing 35 assembled between them, as well as the preload balance over the entire circumference due to thermal expansion, etc. This prevents adverse effects on the preload state, such as loss of preload balance between the rows 38 and 40.

In this embodiment, the adhesive reservoir gap is formed by providing an outer peripheral adhesive reservoir groove in the outer ring support portion, but it may also be formed by providing a groove on the outer ring side or by providing grooves on both sides. is also possible. Further, in this embodiment, one adhesive reservoir gap is provided along both load direction lines 54 and 56, but it may be provided for each load direction line.

[0021] Also, the inner peripheral side adhesive reservoir groove is connected to the hollow rotating shaft 3.
4, or may be provided on both the hollow rotating shaft 34 and the inner ring 37.

FIG. 4 is a sectional view of a brushless spindle motor for driving a hard disk as another embodiment of the present invention.

In this embodiment, two upper and lower adhesive reservoir grooves 70 and 72 each having a triangular cross-section are provided between both rows of rolling balls 38 and 40 in the axial direction. In other respects, this embodiment is similar to the embodiment described above.

FIG. 5 is a sectional view of essential parts of a brushless spindle motor for driving a hard disk as yet another embodiment of the present invention.

In this embodiment, outer circumferential adhesive reservoir grooves 80 and 82 are provided for each of the load direction lines 54 and 56. Inner circumferential adhesive reservoir grooves 84 and 86 are also provided substantially at inner circumferential positions of each rolling ball row 38 and 40, respectively.

88 and 90 are the top plate 9 of the rotor hub 28.
This is an annular stepped portion provided on the lower side of 2. The upper end surface of the inner ring 37 of the double-row radial ball bearing 35 is in contact with the lower surface of the innermost step 88, and the upper end surface of the outer ring 36 is separated from the outer step 90 by a gap. . An annular bending plate 94 projects from the upper end of the outer ring 36 toward the inner ring 37, and the bending plate 94, the outer ring 36, and the stepped portions 88 and 90 constitute a labyrinth seal.

[0027]

Effects of the Invention In the motor of the present invention, the outer ring of the double-row radial ball bearing is securely fixed to the outer ring support part by the adhesive pool gap, and the adhesive pool gap allows each row of the outer ring to be fixed securely. By allowing a certain degree of outward bulging deformation centered on the area where the load direction line of the rolling balls passes, the double row radial ball bearing maintains an appropriate preload state, preventing vibration of the rotational axis and generation of large noises. This maintains good rotational accuracy and extends the life of the bearing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a brushless spindle motor.

FIG. 2 is a sectional view of essential parts showing an assembled state of the brushless spindle motor.

FIG. 3 is a sectional view of essential parts showing an assembled state of the brushless spindle motor.

FIG. 4 is a sectional view of a brushless spindle motor.

FIG. 5 is a sectional view of essential parts of a brushless spindle motor.

[Explanation of sign]

12 Cylindrical support part 35 Double row radial ball bearing 36 Outer ring 38 Rolling sphere row 40 Rolling sphere row 42 Peripheral adhesive reservoir groove 54 Load direction line 56 Load direction line

Claims (1)

[Claims] 1. A double row radial ball bearing in which a fixed position preload is applied by the interaction of both rows of rolling spheres having opposite contact angles, the inner peripheral side being the outer peripheral side of the outer ring of the double row radial ball bearing. and an outer ring support portion bonded to the outer ring support portion, and an adhesive reservoir gap portion including at least a portion where the load direction line of each row of rolling balls intersects with the boundary portion at the boundary portion between the outer ring and the outer ring support portion. A motor characterized in that it has over the entire circumference.