JP2002235737A - Thrust bearing device and small-type motor having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce loss and noise by surely rotating a ball on its own axis responding to the rotation of the axis in receiving the base end of a shaft by a simple constitution, and revolving about an axial center so as to almost eliminate a sliding loss. SOLUTION: In receiving the base end of the energized shaft, this thrust bearing device is provided with a crest projection 1a in the center of a metal base of a bearing housing as a means of positioning, at least, a single ball eccentrically from the center, and a concentric groove 1b formed around the projection. At least, a ball B is disposed in the groove and the base end 3a of the shaft 3 formed by flattening a part abutting on the ball is received via the ball.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thrust bearing device with small sliding loss and a small motor with low loss and low noise provided with the bearing device.

[0002]

2. Description of the Related Art Conventionally, low-loss bearings utilizing ball rolling are well known as radial and thrust bearings.
In general, a small shaft rotating type motor needs to be biased toward the base end of the shaft in order to prevent movement in the axial direction so as not to generate noise during rotation. If this urging force is strong, sliding loss will occur this time. Particularly, in a slotless (fixed yoke) type axial gap type brushless motor, a large loss is caused, which leads to an increase in current consumption. In order to avoid such a loss, a thrust bearing receiving the base end of the shaft may be used by rolling the ball. However, it cannot be used when the shaft diameter is 1 mm or less, and even if it can be used for a slightly large one, the cost is reduced. Will be high.

[0003]

Accordingly, a thrust bearing has been disclosed in which a recess is provided at the center of a bearing housing for receiving a base end of a shaft and one ball is housed therein to constitute a thrust bearing. Although such a structure is simple, the ball is arranged at the center and is received at one point around the base end of the shaft, so that it does not rotate even if the shaft rotates. Therefore, it does not constitute a rolling bearing while utilizing a ball, so that it is not a fundamental solution.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-loss thrust bearing device and a small motor having the same so that the ball can rotate and revolve around the shaft center with a simple structure when receiving the base end of the shaft. It is intended to provide.
Another object of the present invention is to provide a small motor with low noise.

[0005]

A thrust bearing device for solving the above-mentioned problems is a thrust bearing device in which a base end of a biased shaft is received by a ball as in the first aspect of the present invention. Means can be achieved by providing means for displacing at least one ball from the center so that the ball rotates in accordance with the rotation of the shaft and revolves around the axis. With this configuration, the ball rotates reliably in response to the rotation of the shaft with a simple configuration, and revolves around the axis, so that the sliding loss can be minimized. Specifically, as in the invention as set forth in claim 2, the means has a mountain-shaped projection at the center of the bearing housing, a concentric groove around the projection, and at least one ball disposed in the groove. Then, the base end of the shaft having a flat portion in contact with the ball is received through the ball. In this case, the processing of the base end face of the shaft requires only the press cutting barrel polishing, and there is no need to pursue precision. Claim 3
It is preferable that the ball is composed of one ball as shown in FIG. 4 or that the ball is composed of three balls. With a single ball, the shaft generates a force in the radial direction deviated from the center, so that the shaft comes into sliding contact with the radial bearing side, and the clearance noise is reduced. With three balls, the abutting force at the base end of the shaft can be dispersed. According to another configuration of such a thrust bearing device, as in the invention as set forth in claim 5, the means provides a ball housing recess at the bottom of the bearing housing and arranges at least one ball in the recess. By providing a taper from the center of the base end of the shaft, it is possible to achieve the above-described configuration in which the balls are stored eccentrically from the center. Even with this configuration, the ball will rotate and revolve reliably in response to the rotation of the shaft with a simple configuration,
Sliding loss is almost eliminated, and machining of the bearing housing is simplified. In this case as well, one ball is used as described in claim 6, or three balls are used as described in claim 7. In order to make a small motor using such a thrust bearing device, the rotor according to any one of claims 2 to 4 is urged in the proximal direction of the shaft as described in claim 8. 4. A small motor as described above, wherein
This can be attained by providing the thrust bearing device described in the section and a radial bearing device that supports the shaft in the radial direction. A small motor that uses another thrust bearing device and urges the rotor in the proximal direction of the shaft as shown in claim 9. The present invention can also be achieved by providing the above-described thrust bearing device and a radial bearing device that supports the shaft in the radial direction. All of these small motors have low sliding loss and low loss.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is an enlarged sectional view of an essential part of a first embodiment of the thrust bearing device of the present invention. FIG. 2 is a plan view of a main part of the modification of FIG. 1 as viewed from the shaft side. FIG. 3 is an enlarged sectional view of a main part of a second embodiment of the thrust bearing device of the present invention. FIG. 4 is a sectional view of a main part of a modification of FIG. FIG. 5 is a sectional view of an essential part of an axial gap type fixed yoke type small brushless motor using the thrust bearing device of FIG. FIG. 6 is a cross-sectional view of a main part of a radial gap type cored type small motor using the thrust bearing device of FIG.

A thrust bearing device J according to a first embodiment of the present invention has a metal base 1 constituting a part of a bearing housing H and a poly-base constituting another part of the bearing housing H as shown in FIG. A bearing mounting hole 2a is provided at the center of phenylene sulfide resin 2 and integrally formed by outsert molding. At the center of the metal base 1, a mountain-shaped projection 1a is provided by press working and this projection 1a is formed. And a concentric inverted mountain-shaped groove 1b is provided by pressing strongly to obtain a working hardness.
And the base end 3a of the flat shaft 3 is received via the ball B. Further, the sintered oil-impregnated bearing 4 is mounted on the bearing mounting hole 2a for use. In the drawing, reference numeral 1c denotes a reinforcing portion that stands up from a metal base. With such a configuration of the thrust bearing, the ball B contacting the base end 3a of the shaft 3 urged in the base end direction can be used.
Is rotated by the rotation of the shaft, and the groove 1b is
And roll around. Here, in order to prevent noise, the base end of the shaft is preferably filled with grease G. With this configuration, the configuration is extremely simple, and the sliding loss of the shaft in the thrust direction can be greatly reduced.

As shown in FIG. 2, three balls B may be used. Also, if cost is acceptable, 3 or more,
For example, a five-piece arrangement may be used. In such a case, it is suitable for use in a relatively large one, and the force can be dispersed when an impact is applied to the heavy rotor in the axial direction.

FIG. 3 is an enlarged cross-sectional view of an essential part of a thrust bearing device JJ showing a second embodiment of the present invention, and a recess for storing a metal base 11 for restricting a circumferential movement of a dish-shaped ball. 11a is provided, and a rounded 33 is provided toward the base end of the thick shaft 33.
a is formed. In this case, the ball B
Is stored eccentrically from the center, and rotates in accordance with the rotation of the shaft 33, and revolves around the corner of the storage recess 11a. Again, three balls B may be used.

Further, as shown in FIG. 4, a groove 33b for accommodating the ball B may be provided at the base end of the shaft 33 so as to be concentric with the axis. By doing so, the situation is exactly the opposite of that of FIG. 1, but it is clear that the functions are equivalent.

FIG. 5 is a cross-sectional view of a main part of an axial gap type fixed yoke type small brushless vibration motor using the thrust bearing device of FIG. 1. The axial gap type fixed yoke type is generally a face-to-face type. It is said that it is characterized by a large urging force toward the base end of the shaft due to a large attraction force of the magnet.
By providing the above thrust bearing device, brake loss is reduced. Here, the metal base 1 constituting the bearing housing H extends laterally to constitute a stator base, and the polyphenylene sulfide resin 2 constituting the other part of the bearing housing H also extends laterally. In addition, an arrangement guide portion 2b for mounting the air-core armature coil 5 serving as a stator is provided integrally. The rotor R has a diameter of 0.8 mm at the center.
A rotor case 6 to which a thin shaft 3 of a small thickness is attached by laser welding, an arc-shaped tungsten alloy weight 7 and a thin ring-shaped magnet 8 are provided inside the rotor case 6, and the air-core armature coil 5 is provided with an axial gap therebetween. The shaft 3
And is rotatably mounted on the bearing 4. In the drawing, 9 is a non-magnetic stainless steel cover provided with heat insulation function and having poor heat conductivity provided for reflow, and 1d is formed of the same material as the metal base 1 and is separated outside to form a device side. A terminal which is also used for mounting on the printed wiring board 1e by reflow soldering. Reference numeral 6a denotes a through hole provided on the opposite side of the weight in order to move the center of gravity. Reference numeral 1f denotes a printed wiring board for coil terminal relay connection, which does not increase the thickness of the motor itself by being disposed on the inner diameter portion of the ring-shaped magnet 8. With this configuration, a motor in which brake loss is reduced by the thrust bearing device of the present invention can be provided.

FIG. 6 is a cross-sectional view of a main part of a small-diameter radially-cored type cored motor using the thrust bearing device of FIG. 3. An armature coil 55 is wound around a core 12 made of a plate via an insulating coating layer (not shown), and its terminal (not shown) is connected to a cylindrical commutator C1. The cylindrical magnet 88 is housed in a case 99 provided inside so as to face through a radial gap, and the bearing 44 provided on the output side of the case 99 and the thrust provided in the opening of the case 99 It is rotatably mounted by a bearing device JJ. Here, the metal base 11 of the thrust bearing device JJ functions as a bracket for closing the opening of the case 99. As means for biasing the shaft toward the base end side, here, the core 1 is used.
Known conventional means for intentionally shifting the center of the cylindrical magnet 88 from the center of the cylindrical magnet 88 is used. This way,
Since the sliding loss is small and the base 33a of the shaft 33 is rounded, the center of the magnet 88 and the core is shifted by A, so that the biasing force of the shaft 33 causes the ball B to be unevenly distributed. Since the motor 33 moves to the opposite side of the ball and is pressed against the bearing 4, the motor can reduce the clearance noise.

The present invention can take various other embodiments without departing from the technical concept and characteristics thereof. Therefore, the above-described embodiments are merely examples and should not be construed as limiting. The technical scope of the present invention is defined by the appended claims, and is not limited by the description.

[0014]

According to the present invention, as described above, when receiving the base end of the shaft, the ball rotates reliably in response to the rotation of the shaft and revolves around the shaft center with a simple structure. Since the sliding loss can be reduced to a small value, it is possible to provide a low-loss, low-noise thrust bearing device and a small motor provided with the same. Specifically, according to the second aspect of the present invention, the processing of the base end face of the shaft only requires cutting barrel polishing, so that it is not necessary to pursue precision and a rolling bearing can be easily formed. As shown in claims 3 and 4, this ball is 1
In the case of a single ball, a force is generated in the radial direction which is shifted from the center, so that the shaft comes into sliding contact with the radial bearing side while being pressed, so that the clearance noise is reduced. Butting force can be dispersed. Claim 5
With a simple configuration, the ball rotates reliably in response to the rotation of the shaft, and revolves around the axis. Processing becomes simple. All of the small motors provided with these thrust bearing devices have low sliding loss and low loss.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of an essential part of a first embodiment of a thrust bearing device of the present invention.

FIG. 2 is a plan view of a main part of the modification of FIG. 1 as viewed from the shaft side.

FIG. 3 is an enlarged sectional view of an essential part of a second embodiment of the thrust bearing device of the present invention.

FIG. 4 is a sectional view of a main part showing a modification of FIG. 3;

FIG. 5 is a sectional view of an essential part of an axial gap type fixed yoke type small brushless motor using the thrust bearing device of FIG. 1;

6 is a cross-sectional view of a main part of a small-diameter radially-geared cored type motor using the thrust bearing device of FIG. 3;

[Explanation of symbols]

 B Ball R Eccentric rotor R1 Rotor H Bearing housing 1, 11 Metal base 1a Projection 1b Groove 2 Resin 3, 33 Shaft 3a, 33a Shaft base 4,44 Sintered oil-impregnated bearing 5 Air-core armature coil 55 Armature coil

Claims (9)

[Claims] 1. A thrust bearing device in which a base end of a biased shaft is received by a ball, wherein a means for displacing at least one ball from a center is provided, and the ball rotates the shaft. A thrust bearing device that rotates on its own axis and revolves around its axis. 2. The method according to claim 1, wherein the projection has a projection at the center of the bearing housing, and a concentric groove around the projection. At least one ball is disposed in the groove, and a portion contacting the ball is provided. The thrust bearing device according to claim 1, wherein a base end of the flattened shaft is received through the ball. 3. The thrust bearing device according to claim 2, wherein the ball comprises one ball. 4. The thrust bearing device according to claim 2, wherein the number of the balls is three. 5. The device according to claim 1, wherein the ball housing is provided with a ball receiving recess, at least one ball is disposed in the recess, and the ball is tapered from a center of a base end of the shaft. The thrust bearing device according to claim 1, wherein the thrust bearing device is accommodated. 6. The thrust bearing device according to claim 5, wherein the number of the balls is one. 7. The thrust bearing device according to claim 5, wherein the number of the balls is three. 8. A small motor in which a rotor is urged in a direction toward a base end of a shaft, wherein the small motor is provided with the thrust bearing device according to any one of claims 2 to 4. 9. A small motor in which a rotor is urged toward a base end of a shaft, wherein the small motor is provided with the thrust bearing device according to any one of claims 5 to 7.