JP2003262221A - Bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a bearing unit capable of keeping the least setting length of a compression coil spring giving preload onto a pair of outer bearing rings without decrease in a wire diameter and winding the number of turns and easily realizing pulling-in and out of a holding plate during assembling work body means of compression of the compression coil spring. <P>SOLUTION: In the bearing unit 21 arranging the compression coil spring 22 between a pair of the outer bearing right 5 and 7 rotatably supporting a shaft 3 via rolling bodies 4a and 4b, the compression coil spring 22 is provided with a winding diameter changing section changing a winding diameter by a difference two times as much as or more than an outer diameter of a wire material during winding so that a part of winding wire is housed inside other winding wire while compressed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is incorporated in, for example, a drum spindle motor for a VTR or a tape streamer, a disk memory spindle motor such as an LBP motor or an HDD motor, a rotation support portion of a swing arm of an HDD, and other motors. Bearing device

[0002]

2. Description of the Related Art For example, in a drum spindle motor for a VTR or a tape streamer, a bearing device 1 as shown in FIG. 8 is conventionally incorporated as a bearing for supporting the spindle.

This bearing device 1 has raceway grooves 3a and 3b formed at two positions separated from each other in the axial direction on the outer circumference of a shaft 3 which is a spindle of a motor, and rolling elements 4a mounted in the raceway grooves 3a and 3b. , 4b for rotatably supporting the shaft 3 and a pair of bearing outer rings 5, 7.
A pair of spring seats 8a, 8b fitted and attached to the opposite ends of 7.
And a compression coil spring 9 that is mounted between the pair of spring seats 8a and 8b in a compressed state to apply a preload to the pair of bearing outer races 5 and 7.

In the case of the bearing device 1 shown here, the rolling element 4
a and 4b are a large number of balls, and the rolling elements 4a and 4b mounted between the bearing outer rings 5 and 7 and the shaft 3 are the cage 6 respectively.
The distance between rolling elements arranged in the circumferential direction is regulated by a and 6b. In the case of the bearing device 1 shown here,
The compression coil spring 9 is a compression coil spring having a constant winding diameter from a start end seated on one spring seat to an end end seated on the other spring seat.

In the above-described assembly of the bearing device 1, one outer bearing ring 7 is first fitted to the shaft 3, and the rolling element 4b is loaded between the outer bearing ring 7 and the raceway groove 3b of the shaft 3 to form the rolling element. The space between the bearings 4b is regulated by the cage 6b, and the assembly of one bearing outer ring 7 is completed. Next, on the end surface of the bearing outer ring 7, the spring seat 8b, through which the shaft 3 is inserted, the compression coil spring 9, the spring seat 8a, and the pressing plate 11, which is a jig for assembly, are set in this order, and the other bearing outer ring 5 is set. Insert the shaft 3. That state is shown in FIG.

As shown in FIG. 10, the pressing plate 11 has a crescent-shaped rolling element receiver 12 in plan view on a large-diameter collar portion 11b formed with a notch 11a which allows the shaft 3 to be taken in and out from the radial direction. Is projected. When the bearing outer ring 5 inserted through the shaft 3 is eccentric to the shaft 3 in the radial direction, the shaft 3
A crescent-shaped space 14 is formed between the outer ring 5 and the bearing outer ring 5. As shown in FIG. 11, the rolling element receiver 12 supports the rolling element 4 a inserted in the space 14 by being inserted into the space 14.

Then, as shown in FIGS. 11 and 12,
Crescent space 1 between eccentric bearing outer ring 5 and shaft 3
4 is loaded with the rolling element 4a, the pressing plate 11 is pushed down to move the bearing outer ring 5 into the shaft 3 as shown in FIGS.
The positions of the rolling elements 4a are adjusted to be concentric with each other, and the loaded rolling elements 4a are evenly distributed in the circumferential direction. Next, the retainer 6a (see FIG. 8) is mounted, the pressing plates 11 are pulled out in the radial direction of the shaft 3 in a state where the rolling elements 4a are positionally regulated, and the compression coil spring 9 biases the spring seat 8a. When the bearing is seated on the bearing outer ring 5, the assembled state shown in FIG. 8 is obtained.

[0008]

However, the shaft 3 is HD.
In the case of a spindle used in a D motor or the like, the winding diameter of the compression coil spring 9 is usually 10 mm or less,
Further, the space between the bearing outer rings 5 and 7 is also considerably narrowed. Therefore, if the material, wire diameter, and number of turns of the compression coil spring 9 are simply designed from the preload required for each bearing outer ring 5, 7, etc., the close contact length of the compression coil spring 9 becomes large.
As shown in, even if the compression coil spring 9 is contracted to remove the pressing plate 11, the rolling element receiver 12 may not be completely removed from the bearing outer ring 5, and the pressing plate 11 may not be removable. In order to prevent such an inconvenience from occurring, if the wire diameter and the number of turns of the compression coil spring 9 are reduced so that the contact length becomes short, it is necessary to use an expensive spring wire material having high spring performance. As a result, there arises a problem that the manufacturing cost is increased.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to reduce the contact length of a compression coil spring for applying a preload to a pair of bearing outer rings to reduce the wire diameter and the number of turns. Without using expensive spring wire rods that can be kept small and have high spring performance, the pressing plate can be easily inserted / removed during assembly work by compressing the compression coil spring, resulting in low cost assembly. An object is to provide a bearing device having excellent properties.

[0010]

In order to achieve the above object, the bearing device according to the present invention has, as described in claim 1, raceways formed at two positions on the outer periphery of the shaft, which are spaced apart in the axial direction. A groove, a pair of bearing outer rings that rotatably support the shaft via rolling elements that are mounted in the raceway grooves, and a pair of spring seats that are fitted and mounted at opposite ends of the pair of bearing outer rings.
In a bearing device including a compression coil spring that is mounted between the pair of spring seats in a compressed state to apply a preload to the pair of bearing outer rings, the compression coil spring, when compressed,
A winding diameter changing part that changes the winding diameter by a dimensional difference of more than twice the outer diameter of the wire is provided in the middle of winding so that some windings are housed inside other windings. Is characterized by.

In the compression coil spring of the bearing device configured as described above, at the time of compression, a part of the winding having a small winding diameter contracts while being accommodated inside another winding having a large winding diameter. Therefore, the close contact length is a length excluding the winding of a part of the windings accommodated inside the other winding, and has a value smaller than the actual sum of the wire diameter × the number of windings. Therefore, the close contact length of the compression coil spring that applies a preload to the pair of bearing outer rings can be kept small without relying on the reduction of the wire diameter or the number of turns, and without using an expensive spring wire material with high spring performance. A sufficient stroke can be ensured when the compression coil spring is contracted. Therefore, the pressing plate can be easily inserted and removed during the assembling work by compressing the compression coil spring, and the bearing device that is inexpensive and excellent in the assembling property can be provided.

In order to achieve the above object, a bearing device according to a second aspect of the present invention is the bearing device according to the first aspect, wherein the spring seat further includes a seat at an end of the compression coil spring. It is characterized in that a fitting portion that tightly fits the winding portion is provided. With this configuration, the end portion of the compression coil spring can be connected to the spring seat by a simple operation of fitting the end turn portion of the compression coil spring to the fitting portion of the spring seat during assembly. Assembling workability can be improved even in the case of a small bearing having a diameter of 10 mm or less.

In order to achieve the above object, the bearing device according to a third aspect of the present invention is the bearing device according to the first or second aspect, wherein the compression coil spring further has a maximum outer diameter dimension in a preloaded state. Is set to be smaller than the outer diameter dimension of the bearing outer ring having the smaller outer diameter of the pair of bearing outer rings. With this configuration, the compression coil spring does not project radially outward from the bearing outer ring having a small diameter. Therefore, the inner diameter of the housing of a motor or the like incorporating the bearing device is divided into a large diameter portion that matches the outer diameter dimension of the bearing outer ring with one large diameter and a small diameter portion that matches the outer diameter dimension of the bearing outer ring with the other small diameter. Furthermore, the inner diameter of the housing between the large-diameter portion and the small-diameter portion may be adjusted to the outer diameter of the bearing outer ring having a small diameter or only slightly increased, and the end portion of the bearing outer ring having a large diameter abuts. The stepped portion having the inner diameter of the housing can be formed large, so that the housing can be easily processed, and at the same time, the supporting strength of the bearing device by the housing can be improved.

In order to achieve the above object, the bearing device according to a fourth aspect of the present invention is the bearing device according to any one of the first to third aspects, wherein the compression coil spring is further provided with a spring seat. The winding diameters of the end turn portions that are fitted to the fitting portion of the wire are the same, and the winding diameter of the intermediate winding is at least twice the outer diameter of the wire with respect to the winding diameter of the end turn portions. It is characterized in that the dimensional difference is set. By doing so, a common spring seat can be used as the pair of spring seats that support both ends of the compression coil spring, and the number of spring seats to be prepared can be reduced to a single type to reduce costs and improve assembly. be able to.

Further, in order to achieve the above object, the bearing device according to a fifth aspect of the present invention is the bearing device according to any one of the first to fourth aspects, further comprising an effective number of turns of the compression coil spring. The number of turns is 2.5 or more. By doing so, it is possible to prevent the biasing direction of the compression coil spring from tilting with respect to the axial direction due to the excessive number of turns, and the preload of the compression coil spring causes tilting of the bearing outer ring. Can be prevented. Therefore, by preloading the compression coil spring, each outer ring bearing can be held in a proper posture without inclination, and the bearing device can be easily assembled to a housing such as a motor.

Further, in order to achieve the above object, the bearing device according to a sixth aspect of the present invention is the bearing device according to any one of the first to fifth aspects, further comprising: The effective number of turns is set to 0. so that the start end and the end of the end turn are displaced by approximately 180 ° along the winding direction.
It is characterized in that it is set to an odd multiple of 5 turns. With this configuration, even if each bearing outer ring is tilted with respect to the axis of the shaft to be supported by the preload of the compression coil spring, the contact end of the compression coil spring is displaced by about 180 ° at each bearing outer ring. , The pair of bearing outer rings are inclined parallel to each other. Therefore, since the winding start and the winding end of the compression coil spring are set to the same position, compared to the case where the bearing outer rings are inclined in different directions in a V-shape, the bearing device is installed in the housing of the motor or the like. When assembled, even if the inclination due to the preload of the compression coil spring remains in each bearing outer ring, the vibration during rotation can be reduced, and a bearing device with low vibration and low noise can be obtained.

Further, in order to achieve the above object, the bearing device according to a seventh aspect of the present invention is the bearing device according to any one of the first to sixth aspects, wherein both ends of the compression coil spring are not provided. It is characterized by grinding. By doing so, it is possible to reduce the labor required for polishing the end portion of the spring, so that it is possible to improve the productivity and reduce the processing cost.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a bearing device according to the present invention will be described below in detail with reference to the drawings. In the embodiments described below, the same components as those already described with reference to FIGS. 8 to 14 will be denoted by the same or corresponding reference numerals in the drawings to simplify or omit the description.

FIG. 1 shows a first embodiment of a bearing device according to the present invention. The bearing device 21 according to the first embodiment is a bearing that supports a spindle of a drum spindle motor for a VTR or a tape streamer, for example, and is formed at two positions on the outer circumference of the shaft 3 that serves as the spindle in the axial direction. The raceway grooves 3a and 3b and this raceway groove 3
a pair of bearing outer rings 5 and 7 that rotatably support the shaft 3 via rolling elements 4a and 4b that are mounted on a and 3b, and a pair that is fitted and mounted on the opposite ends of the pair of bearing outer rings 5 and 7. 2 and the compression coil spring 22 that is mounted in a compressed state between the pair of spring seats 24 and 25 and applies a preload to the pair of bearing outer rings 5 and 7.

In the case of the bearing device 21 shown here, the rolling elements 4a and 4b are a large number of balls, and the rolling elements 4a and 4b mounted between the bearing outer rings 5 and 7 and the shaft 3 are cages. 6
The distance between rolling elements arranged in the circumferential direction is regulated by a and 6b.

In the case of the bearing device 21 shown here,
The compression coil spring 22 changes the winding diameter by a dimensional difference of at least twice the outer diameter of the wire during the winding so that some windings are accommodated inside other windings during compression. This is a configuration in which a winding diameter changing portion is provided.

More specifically, the compression coil spring 22
Is a first coil portion 22a whose end is seated on a spring seat 24 mounted on the upper bearing outer ring 5, and a third coil portion 22 whose end is seated on a spring seat 25 mounted on the lower bearing outer ring 7.
c and a second coil portion 22b located in the middle between the first coil portion 22a and the third coil portion 22c.

The coil diameters of the first coil portion 22a and the third coil portion 22c at both ends, which are seated on the spring seats, are the same. The winding diameter of the intermediate second coil portion 22b is the same as the first coil portion 22a and the third coil portion 22c at both ends.
With respect to the winding diameter of, the wire diameter is set to be larger than the outer diameter of the wire being used by a dimensional difference of at least twice. Therefore, the two locations, that is, the portion that transitions from the first coil portion 22a to the second coil portion 22b and the portion that transitions from the second coil portion 22b to the third coil portion 22c, are at least twice the outer diameter of the wire rod. It is a winding diameter changing part that changes the winding diameter due to the dimensional difference.

Further, in the case of the present embodiment, the pair of spring seats 24 and 25 have the same structure, and the compression coil spring 22
This is a structure in which a fitting portion 23 that tightly fits with the inner diameter of the end turn portion of the first coil portion 22a or the third coil portion 22c at the end of is fitted and provided.

In the case of the present embodiment, the outer diameter of the upper bearing outer ring 5 is smaller than that of the lower bearing outer ring 7. Said compression coil spring 22, the maximum outer diameter of the preload (i.e., the outer diameter of the second coil portion 22b), and is set smaller than the outer diameter D ₁ of the small diameter of the bearing outer ring 5. Further, the effective number of turns of the compression coil spring 22 is 2.5 or more, and the start end and the end of the end turn of both ends are
The effective number of turns is set to an odd multiple of 0.5 so that the positions are shifted by about 180 ° along the winding direction. In the present embodiment, the effective number of turns of the compression coil spring 22 is 3.5. Both ends of the compression coil spring 22 are not ground.

In the assembly of the bearing device 21 described above, one outer bearing ring 7 is first fitted to the shaft 3, and the rolling element 4b is loaded between the outer bearing ring 7 and the raceway groove 3b of the shaft 3 to form the rolling element. The space between the bearings 4b is regulated by the cage 6b, and the assembly of one bearing outer ring 7 is completed. Next, on the end surface of the bearing outer ring 7, the spring seat 25 through which the shaft 3 is inserted, the compression coil spring 22, the spring seat 24, and the pressing plate 11 that is an assembly jig are set in order, and the bearing outer ring 5 is set on the shaft 3 Insert into. That state is shown in FIG.

The pressing plate 11 is, as shown in FIG.
A crescent-shaped rolling element receiver 12 is provided in a projecting manner on a large-diameter collar portion 11b in which a notch 11a that allows the shaft 3 to be taken in and out from the radial direction is formed. When the bearing outer ring 5 inserted through the shaft 3 is eccentric to the shaft 3 in the radial direction, a crescent-shaped space 14 is formed between the shaft 3 and the bearing outer ring 5. As shown in FIG. 3, the rolling element receiver 12 is inserted into the space 14 so that the rolling element 4 is inserted into the space 14.
support a.

Then, as shown in FIGS. 3 and 4, when the rolling element 4a is loaded in the crescent-shaped space 14 between the eccentric bearing outer ring 5 and the shaft 3, the pressing plate 11 is pushed down.
As shown in FIGS. 5 and 6, the bearing outer ring 5 is positionally adjusted to be concentric with the shaft 3, and the loaded rolling elements 4a are evenly distributed in the circumferential direction. Next, the retainer 6a (see FIG. 1) is attached, and the pressing plate 11 is pulled out in the radial direction of the shaft 3 with the mutual rolling element 4a position regulation, and the spring seat is pressed by the urging force of the compression coil spring 22. When 24 is seated on the bearing outer ring 5, the assembled state shown in FIG. 1 is obtained.

In the compression coil spring 22 of the bearing device 21 thus configured, the windings of the first coil portion 22a and the third coil portion 22c having a small winding diameter are compressed into the second coil portion having a large winding diameter during compression. Since the length of the first coil portion 22a and the third coil portion 22c is accommodated inside the winding of the second coil portion 22b, the contact length is reduced. Is a value excluding, and is a value smaller than the sum of the actual wire diameter x the number of turns.

Therefore, the contact length of the compression coil spring 22 for applying a preload to the pair of bearing outer rings 5, 7 can be kept small without relying on the reduction of the wire diameter or the number of turns, and the spring performance is high and expensive. Compression coil spring 2 without using spring wire
When 2 is contracted, a sufficient stroke can be secured. Therefore, the pressing plate 11 can be easily inserted and removed during the assembling work by compressing the compression coil spring 22, and the bearing device 21 that is inexpensive and has excellent assemblability can be provided.

Further, in the bearing device 21 of the present embodiment,
Each spring seat 24, 25 is provided with a fitting portion 23 that tightly fits into the inner diameter of the end turn portion of the compression coil spring 22. At the time of assembly, the end turn portions of the compression coil spring 22 are provided. The end portion of the compression coil spring 22 is attached to the spring seats 24, 25 by a simple operation of fitting the spring seats 24, 25 to the fitting portion 23.
It is possible to connect to No. 25, and it is possible to improve the assembling workability even in the case of a small bearing having an outer diameter of 10 mm or less.

Further, in the present embodiment, the maximum outer diameter dimension of the compression coil spring 22 in the preloaded state is set smaller than the outer diameter dimension of the bearing outer ring 5 having the smaller outer diameter.
That is, the compression coil spring 22 does not protrude outward in the radial direction from the bearing outer ring 5 having a small diameter. Therefore, the inner diameter of the housing of the motor or the like in which the bearing device 21 is incorporated has a large diameter portion that matches the outer diameter dimension of the bearing outer ring 7 having a large diameter, and a small diameter portion that matches the outer diameter dimension of the small bearing outer ring 5.
Further, the inner diameter of the housing between the large-diameter portion and the small-diameter portion may be adjusted to the outer diameter of the bearing outer ring 5 having a small diameter or only slightly increased, and the housing with which the end portion of the bearing outer ring 7 having a large diameter abuts. Since the step portion having the inner diameter can be formed large, the housing can be easily processed, and at the same time, the supporting strength of the bearing device 21 by the housing can be improved.

Further, in the present embodiment, in the compression coil spring 22, the winding diameters of the first coil portion 22a and the third coil portion 22c having the end turn portion fitted to the fitting portion 23 of the spring seat are made the same. ing. Therefore, a common spring seat can be used for the pair of spring seats 24 and 25 that support both ends of the compression coil spring 22, and the number of spring seats to be prepared can be reduced to a single type to reduce costs and improve assemblability. Can be planned.

Further, in the present embodiment, since the effective number of turns of the compression coil spring 22 is 2.5 or more, the biasing direction of the compression coil spring 22 with respect to the axial direction is too small. Can be prevented from tilting. That is, it is possible to prevent the inconvenience that the preload by the compression coil spring 22 causes the bearing outer rings 5, 7 to tilt.
Therefore, by preloading the compression coil spring 22, the outer ring bearings 5 and 7 can be held in proper postures without inclination, and the bearing device can be easily assembled to a housing such as a motor.

Further, the compression coil spring 22 in the present embodiment has an effective number of turns of 0.5 so that the start end and the end of the end turn at both ends are displaced by about 180 ° along the winding direction. Since the bearing outer rings 5 and 7 are set to be an odd multiple of, even if the respective bearing outer rings 5 and 7 are inclined with respect to the axis of the shaft 3 supported by the preload by the compression coil spring 22, the pair of bearing outer rings 5 and 7 are parallel to each other Lean. Therefore, compared with the case where the winding start and the winding end of the compression coil spring 22 are set to the same position and the bearing outer rings are inclined in different directions in a V-shape, the bearing device 21 is mounted in a housing such as a motor. Even when the inclination due to the preload of the compression coil spring 22 remains in each of the bearing outer rings 5, 7 when assembled, the vibration during rotation can be reduced, and the bearing device 21 with low vibration and low noise can be obtained. You can

Further, in this embodiment, both ends of the compression coil spring 22 are not ground, and the labor required for polishing the spring end portions can be reduced, so that productivity can be improved and processing cost can be reduced. it can.

FIG. 7 is a vertical sectional view of the second embodiment of the bearing device according to the present invention. The bearing device 31 of the second embodiment has a pair of spring seats 27 and 28 and a compression coil spring 26 instead of the pair of spring seats 24 and 25 and the compression coil spring 22 of the first embodiment.
Is used. In the bearing device 31, the configuration other than the spring seats 27 and 28 and the compression coil spring 26 is common to the case of the first embodiment. The same components are designated by the same reference numerals and the description thereof will be omitted.

The compression coil spring 2 of the second embodiment
6 also includes a first coil portion 26a whose end portion is seated on a spring seat 27 attached to the upper bearing outer ring 5, and a third coil portion 2 whose end portion is seated on a spring seat 28 attached to the lower bearing outer ring 7.
6c and a second coil portion 26b located in the middle between the first coil portion 26a and the third coil portion 26c. Then, the first coil portion 26a
The winding diameters of the third coil portion 26c and the third coil portion 26c are set to be the same. Further, the winding diameter of the intermediate second coil portion 26b is
The diameter is set to be smaller than the diameters of the first coil portion 26a and the third coil portion 26c at both ends by a dimensional difference twice or more the wire diameter.

The first coil portion 26a and the third coil portion 26, which are the maximum diameter portions of the winding diameter of the compression coil spring 26, are also included.
The outer diameter of c is set smaller than the outer diameter of the upper bearing outer ring 5 having a small diameter. Also in the case of the compression coil spring 26, the effective number of turns is set to 2.5.

Further, in the case of the present embodiment, the pair of spring seats 27, 28 includes the first coil portion 26a and the third coil portion 2
This is a structure in which a tubular fitting portion 29 that is tightly fitted is formed on the outer circumference of the end turn portion of 6c.

Even in the structure using the compression coil spring 26 described above, as in the first embodiment, at the time of compression, a small diameter is formed inside the first coil portion 26a and the third coil portion 26c having a large winding diameter. The second coil portion 26b is accommodated, and the contact length can be reduced. Therefore, also in the bearing device of this embodiment, it is possible to achieve the action and effect by reducing the contact length, as in the case of the first embodiment.

[0042]

As described above, according to the bearing device of the present invention as set forth in claim 1, the compression coil spring for preloading the pair of bearing outer rings has a small winding diameter when compressed. Since the wire contracts while being accommodated inside another winding with a large winding diameter, the close contact length is the length excluding the winding of some of the windings accommodated inside the other winding. , Which is smaller than the actual sum of wire diameter x number of turns. Therefore, the close contact length of the compression coil spring that applies a preload to the pair of bearing outer rings can be kept small without relying on the reduction of the wire diameter or the number of turns, and without using an expensive spring wire material with high spring performance. A sufficient stroke can be ensured when the compression coil spring is contracted. Therefore, the pressing plate can be easily inserted and removed during the assembling work by compressing the compression coil spring, and the bearing device that is inexpensive and excellent in the assembling property can be provided.

Further, in the bearing device according to the second aspect, at the time of assembly, the end portion of the compression coil spring is spring-loaded by a simple operation of fitting the end turn portion of the compression coil spring into the fitting portion of the spring seat. Even in the case of a small bearing that can be connected to a seat and has an outer diameter of 10 mm or less, the assembling workability can be improved.

Further, in the bearing device according to the third aspect, the compression coil spring does not protrude outward in the radial direction from the bearing outer ring having a small diameter. Therefore, the inner diameter of the housing of a motor or the like incorporating the bearing device is divided into a large diameter portion that matches the outer diameter dimension of the bearing outer ring with one large diameter and a small diameter portion that matches the outer diameter dimension of the bearing outer ring with the other small diameter And further,
The inner diameter of the housing between the large diameter portion and the small diameter portion is
It is only necessary to match or slightly increase the outer diameter of the bearing outer ring with a small diameter, and it is possible to form a large step portion of the housing inner diameter with which the end of the bearing outer ring with a large diameter contacts.
It is possible to facilitate the processing of the housing, and at the same time, improve the support strength of the bearing device by the housing.

Further, in the bearing device according to the fourth aspect, a common spring seat is used for the pair of spring seats that support both ends of the compression coil spring, so that the number of spring seats to be prepared can be reduced to a single type, and the cost can be reduced. Can be reduced and the assemblability can be improved.

Further, in the bearing device according to the fifth aspect, it is possible to prevent the biasing direction of the compression coil spring from being inclined with respect to the axial direction because the number of turns is too small. That is, it is possible to prevent the inconvenience that the preload of the compression coil spring causes the bearing outer ring to tilt. Therefore, by preloading the compression coil spring, each outer ring bearing can be held in an appropriate posture without inclination, and the motor or the like can be easily assembled to the housing.

Further, in the bearing device according to the sixth aspect, even if each of the bearing outer rings is inclined with respect to the axis of the shaft to be supported by the preload of the compression coil spring, the compression coil springs of the respective bearing outer rings are Since the contact ends are offset by about 180 °, the pair of bearing outer rings are inclined parallel to each other. Therefore, since the winding start and the winding end of the compression coil spring are set to the same position, compared to the case where the bearing outer rings are inclined in different directions in a V-shape, the bearing device is installed in the housing of the motor or the like. When assembled, even if the inclination due to the preload of the compression coil spring remains in each bearing outer ring, the vibration during rotation can be reduced, and a bearing device with low vibration and low noise can be obtained.

Further, in the bearing device according to the seventh aspect, the labor required for polishing the end portions of the spring can be reduced, so that the productivity can be improved and the processing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a bearing device according to a first embodiment of the present invention in an assembled state.

FIG. 2 is a vertical cross-sectional view of the bearing device shown in FIG. 1 in an initial state of assembly.

FIG. 3 is a vertical cross-sectional view showing a state in which rolling elements are mounted between a shaft and an outer ring in the state shown in FIG.

FIG. 4 is a transverse cross-sectional view showing the positional relationship among the shaft, the bearing outer ring, and the rolling elements at the stage of the assembly shown in FIG.

FIG. 5 is a vertical cross-sectional view of the state shown in FIG. 3 in which the bearing outer ring, which has been eccentric to the shaft after the loading of the rolling elements, is returned to the concentric state with respect to the shaft.

6 is a transverse cross-sectional view showing the positional relationship among the shaft, the bearing outer ring, and the rolling elements in the intermediate stage of assembly shown in FIG.

FIG. 7 is a vertical sectional view of a bearing device according to a second embodiment of the present invention in an assembled state.

FIG. 8 is a vertical cross-sectional view of a conventional bearing device in an assembled state.

FIG. 9 is a vertical cross-sectional view of a conventional bearing device in an initial stage of assembly.

FIG. 10 is a plan view of a holding plate used for assembling the bearing device.

FIG. 11 is a vertical cross-sectional view showing a state in which a conventional bearing device is being assembled.

FIG. 12 is a transverse cross-sectional view showing the positional relationship among the shaft, the bearing outer ring, and the rolling elements at the intermediate stage of assembly shown in FIG.

FIG. 13 is a vertical cross-sectional view showing a state in which the bearing outer ring, which has been eccentric to the shaft after loading the rolling elements, is returned to the concentric state with respect to the shaft.

14 is a transverse cross-sectional view showing the positional relationship between the shaft shown in FIG. 13 and an upper bearing outer ring.

[Explanation of symbols]

3 axes 3a, 3b Track groove 4a, 4b Rolling element (ball) 5,7 Bearing outer ring 11 Press plate 12 Rolling element support 21 Bearing device 22 Compression coil spring 22a 1st coil part 22b Second coil portion 22c Third coil section 24,25 spring seat 26 Compression coil spring 26a 1st coil part 26b Second coil section 26c Third coil section 27, 28 Spring seat 31 Bearing device

Claims (7)

[Claims] 1. A raceway groove formed at two positions on the outer circumference of the shaft, spaced apart in the axial direction, and a pair of bearing outer rings rotatably supporting the shaft via rolling elements mounted in the raceway groove,
A bearing provided with a pair of spring seats fitted and attached to the opposite ends of the pair of bearing outer rings, and a compression coil spring that is mounted between the pair of spring seats in a compressed state to apply a preload to the pair of bearing outer rings. In the device, the compression coil spring is wound with a dimensional difference of not less than twice the outer diameter of the wire during the winding so that a part of the winding is housed inside the other winding during compression. A bearing device having a winding diameter changing portion for changing the diameter. 2. The bearing device according to claim 1, wherein the spring seat is provided with a fitting portion that fits into the end turn portion of the compression coil spring. 3. The compression coil spring has a maximum outer diameter dimension set in a preload state smaller than an outer diameter dimension of a bearing outer ring having a smaller outer diameter of the pair of bearing outer rings. The bearing device according to claim 1. 4. In the compression coil spring, the winding diameters of the end winding portions fitted at the fitting portions of the spring seat are the same, and the winding diameter of the intermediate winding is the end winding portions at both ends. The bearing device according to any one of claims 1 to 3, wherein a dimensional difference of at least twice the outer diameter of the wire is set with respect to the winding diameter. 5. The effective number of turns of the compression coil spring is 2.
The bearing device according to any one of claims 1 to 4, wherein the number of turns is 5 or more. 6. The effective number of turns of the compression coil spring is set to an odd multiple of 0.5 so that the start end and the end of the end turn at both ends are displaced by about 180 ° along the winding direction. The bearing device according to any one of claims 1 to 5, which is characterized in that. 7. The bearing device according to claim 1, wherein both ends of the compression coil spring are not ground.