JPH08149748A - Motor - Google Patents

Abstract

PURPOSE: To obtain a highly reliable motor in which highly accurate bearing can be sustained without causing leakage or depletion of lubricant fluid while reducing the size with high speed rotation. CONSTITUTION: The motor comprises a housing 1, a shaft member 2 secured to the housing 1, a rotor 3 supported rotatably with relative to the shaft member 2, and a dynamic bearing means of fluid lubricant interposed between the shaft member and a rotor 3. In order to prevent leakage of the lubricant fluid, a tapered sealing structure is employed such that the radial gap between the shaft member 2 and the rotor 3 increases gradually toward the outside of the motor at the opposite ends of a dynamic pressure bearing means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor using a hydrodynamic bearing as a bearing portion with a fluid lubricant.

[0002]

2. Description of the Related Art For example, an electric motor such as a spindle motor incorporated in a recording disk drive requires a rotating member with high precision due to the nature of the driving load, and also requires accurate rotation support that minimizes runout and rattling. To be done. In order to meet such demands, the conventional ball bearing has been replaced in the bearing portion by a dynamic pressure bearing means using a fluid lubricant, and various configurations accompanying it have been proposed. In particular, the electric motor used for the above-mentioned applications is required to have the axial (thrust) play of the rotor as little as possible. Therefore, in addition to the radial dynamic pressure bearing, a configuration using a thrust dynamic pressure bearing in combination is adopted.

For example, in Japanese Patent Publication No. 63-43606,
A thrust dynamic bearing configuration is shown. The dynamic pressure generating groove 1 is formed on both end faces of the thrust bearing collar (thrust plate) 10.
3, 13 ′ are provided, and the housing 11 is configured so as to sandwich the thrust plate 10. A lubricating oil 12 is filled between the thrust plate 10 and the housing 11. However, in such a structure, there is a drawback that the lubricating oil is pushed out and leaks out due to rotation / stop operation around the bearing, change in ambient temperature, and the like.

On the other hand, the applicant of the present application filed a patent application for a structure in which an air chamber is provided on the outer peripheral end side of the thrust plate 10 so as to separate the lubricant in the dynamic pressure generating grooves 13, 13 '. It was proposed in Japanese Patent Application No. 208-237 and Japanese Patent Application No. 5-259052. As a result, the pressure difference surrounding the bearing inside the dynamic pressure bearing is eliminated, and the lubricant is prevented from being pushed out.

[0005]

However, in recent years,
Various OA devices and the like in which electric motors are incorporated are becoming smaller in size and rotating at a higher speed. Therefore, the amount of fluid lubricant such as lubricating oil retained at both end surfaces of the thrust plate is reduced, while The centrifugal force generated by the high-speed rotation of the rotor makes it easier for the fluid lubricant in the thrust plate to flow out. The leakage of the fluid lubricant makes it impossible to maintain stable and highly accurate bearing support in the dynamic pressure bearing portion, which causes a significant reduction in bearing life.

The present invention has been made in view of the above-mentioned problems existing in the prior art, and the problem is that it is possible to realize downsizing and high speed rotation, and An object of the present invention is to provide a highly reliable electric motor capable of maintaining highly accurate bearing support without leakage or depletion.

[0007]

In order to achieve the above object, an electric motor according to the present invention includes a housing, a shaft member fixed to the housing, and a rotor which is rotatably supported relative to the shaft member. , A dynamic pressure bearing means by a fluid lubricant interposed between the shaft member and the rotor, and in order to prevent leakage of the fluid lubricant, the shaft is provided at both ends of the dynamic pressure bearing means. An electric motor having a taper seal structure in which a radial gap between a member and the rotor is provided with a tapered gap that increases with the outside of the electric motor; the shaft member protrudes radially outward over the entire circumference. A thrust plate is provided, and the rotor includes a sleeve rotatably supported by the shaft member, and a thrust cover that covers the thrust plate; between the sleeve and the shaft member. Dialkyl bearing portion is provided between an end portion of said sleeve and said thrust plate, and between the thrust cover and the thrust plate, respectively,
A thrust bearing portion is provided; a radial gap between the thrust plate and the sleeve is set to be smaller than a maximum gap of the taper seal structure, and the sleeve and the sleeve are provided on the outer peripheral end side of the thrust plate. An annular gap having a substantially constant gap defined by the thrust cover is provided, and a larger concave portion is provided on the sleeve side in the annular gap; the concave portion serves as an air chamber, and the air chamber pressure of the concave portion is provided outside the electric motor. A communication hole is provided to make the pressure substantially equal to the atmospheric pressure.

Further, in the above electric motor, the communication hole in the annular gap is provided as a hollow projecting portion which is provided so as to project inward from the inner surface defining the annular gap, and the shaft member and the rotor are connected to each other. With the relative rotation, the hollow protrusion serves as pushing means for pushing the fluid lubricant in the annular gap to the upper and lower end portions of the thrust plate, and the sleeve side wall surface in the annular gap and the annular gap. It is preferable that the fluid lubricant in and is integrated with the fluid lubricant on both upper and lower ends of the thrust plate of the thrust bearing portion.

Further, the thrust plate is provided with a hole communicating from the outer peripheral end of the thrust plate to the inner peripheral side of the thrust plate bearing portion.
It is desirable to supply the fluid lubricant on the outer peripheral end side of the thrust plate to the thrust bearing portion. Further, a groove portion that is opened outward in the radial direction is provided on the outer peripheral end portion of the thrust plate over the entire circumference, and an electric motor that provides the fluid lubricant on the outer peripheral end portion side of the thrust plate is provided by the groove portion. It

[0010]

According to the electric motor of the present invention, the radial gap between the thrust plate and the sleeve is set to be smaller than the maximum gap of the taper seal structure provided at both ends of the electric motor. For this reason, the fluid lubricant held in the thrust bearing portion is held inside the electric motor without being subjected to an acting force that leaks out of the electric motor. As a result, the fluid lubricant is retained and retained even in the annular gap. Further, in the annular gap, a larger concave portion is provided on the sleeve side, and further, in this concave portion, there is provided a communication hole for making the air chamber pressure substantially equal to the atmospheric pressure outside the electric motor. At, the pressure difference between the inside and outside of the electric motor is eliminated. This prevents the fluid lubricant from being extruded from the inside of the electric motor to the outside.

Further, according to the electric motor of the present invention, the communication hole in the annular gap is provided as a hollow protrusion provided inwardly from the inner surface defining the annular gap, and is connected to the shaft member. With the relative rotation with the rotor, the hollow protrusion serves as a pushing means for pushing the fluid lubricant in the annular gap to both upper and lower end sides of the thrust plate, and the inside and the annular gap. The fluid lubricant on the side wall surface of the sleeve is integrally connected to the fluid lubricant on both upper and lower end sides of the thrust plate of the thrust bearing portion. As a result, the fluid lubricant retained / held in the annular gap is easily recovered or supplied to the thrust dynamic pressure bearing portion, and exhaustion or shortage of the fluid lubricant is eliminated.

Further, the thrust plate is provided with a hole communicating from the outer peripheral end of the thrust plate to the inner peripheral side of the thrust plate bearing portion, and the hole is provided on the outer peripheral end side of the thrust plate. The fluid lubricant can be supplied to the thrust bearing portion. In addition, a groove portion that is open outward in the radial direction is provided at the outer peripheral end portion of the thrust plate, and the fluid lubricant on the outer peripheral end portion side of the thrust plate is captured by the groove portion. As a result, the fluid lubricant can be easily collected or supplied to the thrust bearing portion.

[0013]

Embodiments of an electric motor according to the present invention will be described with reference to the accompanying drawings. To do. FIG. 1 is an overall sectional view of an electric motor for rotating a recording disk, for example. 2 is an enlarged sectional view showing the upper portion of FIG. 1 and the peripheral portion of the thrust plate 5, and FIG. 3 is an enlarged sectional view showing the lower peripheral portion of the sleeve 4 of FIG. In these drawings, the same numbers are given to the same members and parts.

In FIG. 1, the housing 1 is made of an aluminum alloy, and a boss portion 16 is formed at the center of the housing 1 so as to bulge upward (inside the electric motor). The boss portion 16 is provided with the hole portion 15 at the center thereof,
The lower end of the shaft 2 is fitted and fixed. The shaft 2 is mounted substantially perpendicular to the mounting surface of the housing 1. The shaft 2 is made of, for example, an iron-based alloy, and a disk-shaped thrust plate 5 is integrally provided on the upper end side. The thrust plate 5 is provided with respect to the longitudinal (axial) direction of the shaft 2.
The upper and lower ends 33, which are formed substantially at right angles,
The surfaces 34 are formed so as to be substantially parallel to each other.

The rotor 3 rotatably supported on the shaft 2 is
It has a substantially cylindrical sleeve 4 and a hub 10 fixed to the outer peripheral side of the sleeve 4. The hub 10 is formed of, for example, an aluminum alloy, and a recording disk (not shown) as a rotational load is externally fitted and mounted on the outer peripheral portion 49 of the hub 10. The flange 41 of the hub 10 is for receiving the recording disk, the hole 20 is a screw hole for attaching a clamp member, and the hole 21 is a stick hole for preventing rotation when fixing the recording disk.

The sleeve 4 is composed of a cylindrical peripheral wall 24 occupying most of the entire length of the sleeve 4, and an enlarged diameter portion 25 integrally provided on the upper portion thereof, which are formed coaxially with the shaft 2. . The sleeve 4 is made of a copper alloy material such as lead bronze. Expanded portion 25 of sleeve 4
Has a step portion 27 formed on the inner peripheral side thereof, an intake pipe 26 is provided in the lower portion of the step portion 27, and a through hole 30 communicating with the outside of the electric motor is formed in the lower portion thereof. The intake pipe 26 and the through hole 30 are provided in two symmetrical positions with respect to the axis of the sleeve 4. In addition,
The electric motor internal space 38 communicating with the through hole 30 communicates with the electric motor external space (in this embodiment, a recording disk storage space) 39 through a gap between the housing 1 and the flange portion 41 of the hub 10.

A thrust cover 6 is mounted on the step 27 of the sleeve 4. The thrust cover 6 has a ring shape, the outer peripheral portion of which is fitted on the inner peripheral side of the upper portion of the sleeve 4, and the upper end portion 32 is caulked and tightly fixed to the sleeve 4. The inner peripheral portion 57 of the thrust cover 6 faces the outer peripheral portion 19 of the shaft 2 with a slight gap. The sleeve 4, the hub 10, and the thrust cover 6 fixed to the sleeve 4 are rotatably supported on the shaft 2.

The boss portion 16 of the housing 1 is provided with a step portion 17 on the upper outer periphery thereof, and the stator 7 is fixed to the step portion 17. In the stator 7, the stator coil 11 is wound around a stator core 12 having predetermined magnetic pole teeth. The coil lead wire 13 drawn out from the stator coil 11 is connected to the flexible circuit board 14 adhered on the housing 1, and a connection wire not shown is led out of the electric motor via the insulating bush 23. A rotor magnet 8 is mounted via a magnetic yoke 9 on the hub 10 side (the inner peripheral portion 18 of the hub 10) that faces the stator 7 in the radial direction. Therefore, when a predetermined electric signal is applied to the coil lead wire 13, electromagnetic interaction between the rotor magnet 8 and the stator 7 causes the rotor 3 (hub 1
0) is driven to rotate.

Rotational support of the rotor 3 with respect to the shaft 2 is achieved by a dynamic pressure bearing via a fluid lubricant made of lubricating oil. In the substantially central portion of the outer peripheral portion 19 of the shaft 2,
There is provided a reduced diameter portion 35 formed by slightly reducing the outer diameter of the outer peripheral portion 19. Outer peripheral portions 47 and 48 having outer peripheral surfaces formed with a predetermined outer diameter dimension are provided on both sides in the vertical direction. The outer peripheral portions 47 and 48 are
The radial dynamic pressure bearing portions A and B are constituted by these and the sleeve 4 which is fitted in the radial direction and faces each other. In order to configure the radial dynamic pressure bearing portions A and B, a herringbone-shaped dynamic pressure generating groove formed at predetermined intervals in the circumferential direction is formed at the corresponding portion of the inner peripheral portion 31 of the sleeve 4, although not shown. It is provided all around. The dynamic pressure generating groove may be provided on the outer peripheral portions 47, 48 side of the shaft 2 facing the sleeve 4 side.

The lower end portion 52 of the thrust cover 6, the upper end portion 33 of the thrust plate 5 that axially opposes the lower end portion 52, and the lower end portion 34 of the thrust plate 5 that faces in the same direction as the peripheral wall of the sleeve 4 (the peripheral wall). The upper end portion 44 (of 24) constitutes thrust dynamic pressure bearing portions C and D.
Since the thrust dynamic pressure bearing portions C and D are configured, the upper and lower end portions 33 and 34 of the thrust plate 5 have a herringbone or spiral dynamic pressure formed at predetermined intervals in the circumferential direction although not shown. Generation grooves are provided all around. The dynamic pressure generating grooves may be provided on the lower end portion 52 side of the thrust cover 6 and the upper end portion 44 side of the sleeve 4 which face each other.

The electric motor of this embodiment will be described in more detail with reference to FIGS. 2 and 3. FIG. 2 mainly shows a portion of the thrust plate 5, (a) is a plan view of the thrust plate 5 seen from above with the thrust cover 6 removed, and (b) is a peripheral portion of the thrust plate 5. FIG. In FIGS. 2A and 2B, the thrust dynamic pressure bearing portions C and D are provided with a fluid lubricant interposed therebetween. The thrust cover 5 (lower end portion 52) and the sleeve 4 (step portion 25) are provided on the outer peripheral end side of the thrust plate 5.
An annular gap 60 defined by the inner peripheral portion 61 and the upper end portion 44) of the peripheral wall 24 is provided. The annular gap 60 communicates with the through hole 30 through the opening 22 of the intake pipe 26, so that the space pressure in the annular gap 60 is set to be substantially equal to the atmospheric pressure outside the electric motor.

At the outer peripheral end of the thrust plate 5, there is provided an annular groove 29 which is open to the outside over the entire circumference.
The annular groove 29 has a maximum opening at the outer peripheral end and is narrowed inward, and has a tapered shape in the illustrated example. The thrust plate 5 is provided with holes 50 and 51 communicating with the thrust dynamic pressure bearing portions C and D of the upper and lower end portions 33 and 34 to the annular groove 29.

The fluid lubricant retained in the thrust dynamic pressure bearing portions C and D is retained in the respective dynamic pressure generating portions, and the annular gap 60 eliminates the pressure difference between the inside and outside of the electric motor. Stable bearing support is maintained without the action of the lubricant moving. If, for example, the high-speed rotation drive of the electric motor or the shock applied to the electric motor,
Even if the fluid lubricant is scattered from the dynamic pressure generating portions to the annular gap 60 or leaks to the inner peripheral wall 61 or the end portion 44 that defines the annular gap, it is received and retained in the annular gap 60. The fluid lubricant retained in the annular gap 60 is captured by the annular groove 29. Since the annular groove 29 is formed in a tapered shape, the fluid lubricant can be easily captured by the capillary phenomenon. The fluid lubricant captured in the annular groove 29 is recovered again to the dynamic pressure generating portions of the thrust dynamic pressure bearing portions C and D via the internal supply passages 50 and 51.
Therefore, even if the fluid lubricant is insufficient in both the dynamic pressure generating portions, the required amount is constantly supplied, so that bearing support failure due to exhaustion or lack of the fluid lubricant does not occur. The annular gap 6
Since the opening 22 of the intake pipe 26 projects inward of the gap space, the fluid lubricant that has been scattered and leaked to 0 does not leak to the outside of the motor through this opening 22.

In addition to the above-mentioned unexpected accident, the annular gap 60
Since it is possible to supply a sufficient amount of fluid lubricant to the thrust dynamic pressure bearing portions C and D by previously filling it with an excess amount of fluid lubricant, this configuration ensures a sufficient bearing life. You can 4 and 5 correspond to FIG. 2 and show the movement of the fluid lubricant due to the rotation of the electric motor. The action of the intake pipe 26 on the fluid lubricant by the relative rotational movement of the sleeve 4 with respect to the shaft 2 will be described. In FIG. 4, the fluid lubricant is held in the annular gap 60 in the state as shown in FIG. At this time, it is assumed that the intake pipe 26 moves relatively to the supply paths 50 and 51 of the thrust plate 5 due to the rotation of the electric motor.

Then, as shown in FIG. 5, the intake pipe 26
When the liquid lubricant reaches the position of the supply passages 50, 51, the liquid lubricant rises due to the capillary action by the side wall 28 of the intake pipe 26, and the action force of the intake pipe 26 accompanying the rotation causes the annular groove 29. It is pushed into the supply paths 50 and 51 via. That is, the intake pipe 26 serves as an extruding means for adjusting the air pressure inside the annular gap 60 and forcibly sending the fluid lubricant to the thrust dynamic pressure bearing portions C and D. As is apparent from the above description, the side wall 28 of the intake pipe 26 is provided close to the annular groove 29 side of the thrust plate 5 and the inner peripheral wall 61 of the sleeve 4, respectively, so that the thrust of the fluid lubricant is Dynamic bearing C, D
The push-out effect to the Furthermore, the intake pipe 2
By making the height of 6 protruding as high as possible,
It is possible to promote the capillary phenomenon of the fluid lubricant into the annular groove 29 and prevent the fluid lubricant from leaking from the opening 22 by itself. Then, due to the retained amount (reserved amount) of the fluid lubricant staying in the annular gap 60, the side wall 28 of the intake pipe 29 causes the fluid lubricant of the peripheral wall 61 and the end portion 44 forming the annular gap 60 to pass through the thrust bearing portion C. Needless to say, it becomes easy to integrate and integrate the fluid lubricants of D and D.

In FIG. 2, the fluid lubricant retained in the dynamic pressure generating portion on the thrust dynamic pressure bearing portion C side is prevented from leaking to the outside of the motor, that is, the upper side of the drawing by the following configuration. There is. An annular groove 36 is provided in the outer peripheral portion 19 of the shaft 2, and the gap between the annular groove 36 and the inner peripheral portion 57 of the thrust cover 6 is increased. Further, the inner side 62 of the inner peripheral portion 57 of the thrust cover 6 is formed in a tapered shape. Therefore, even if the fluid lubricant of the dynamic pressure generating portion leaks to the outside of the electric motor (to the upper side of the drawing), the two gaps prevent the fluid lubricant from leaking due to the surface tension acting on the fluid lubricant. It should be noted that these parts 57 and 62 of the thrust cover 6, the outer peripheral portion 19 of the shaft 2, and the annular groove 36.
By applying an oil repellent agent that repels the fluid lubricant to the above portion, leakage of the fluid lubricant can be prevented more effectively.

On the other hand, on the lower side of the sleeve 4 shown in FIG. 3, a radial dynamic pressure bearing portion B is provided. In order to prevent the fluid lubricant in the dynamic pressure generating portion from leaking to the outside of the electric motor, the following structure is provided. That is, the inner peripheral portion 31 of the sleeve is provided with the taper portion 40 on the lower end side thereof, and the gap between the inner peripheral portion 31 and the outer peripheral portion 48 of the shaft 2 balances the movement of the fluid lubricant with a predetermined surface tension. It is held at the part where it is opened and is prevented from leaking to the outside of the electric motor (lower side in the figure). In the unlikely event that an action force acts on the fluid lubricant to leak due to impact or other reasons, the surface tension of the annular groove 37 of the shaft 2 and the annular groove 43 of the inner peripheral portion of the sleeve 4 is reduced by the clearance. It is possible to prevent leakage. In particular, by applying an oil repellent agent that repels the fluid lubricant to the portions of the annular grooves 37 and 43, the leakage prevention effect can be enhanced.

Here, the tapered portion 6 of the thrust cover 6
2 and the tapered portion 40 of the sleeve 4 respectively, the tapered gap portions 98 and 99 are for preventing the leakage of the fluid lubricant outside the motor, as described above, and therefore, these are tapered. It has a seal structure.
These tapered seal structures prevent leakage of the fluid lubricant on both end sides of the electric motor. In addition, including this embodiment and another embodiment described below, the gap size of the members facing each other in each of the dynamic pressure bearing portions A, B, C, D is the maximum gap of the tapered gap portions 98, 99. It is set smaller than the part (as seen in the figure, the outside of the motor). As a result, the fluid lubricant interposed in each dynamic pressure generating portion is retained inside the electric motor due to the surface tension and the capillary phenomenon, and is not subjected to the acting force leaking to the outside of the electric motor.

Next, FIG. 6 shows another embodiment of the electric motor according to the present invention, (a) is a plan view of the thrust plate as seen from above with the thrust cover removed, and (b). Is a sectional view thereof. FIG. 6 is a configuration in accordance with FIG. 2 already shown, and the same parts are denoted by the same numbers. 2 is different from the configuration of FIG. 2 in that instead of the intake pipe 26 of FIG. 2, a stepped portion 63 is provided in the expanded diameter portion 25 of the sleeve 4 in FIG.
4 are provided. Also in this case, the same effect as that of FIG. 2 can be obtained. By increasing the height of the stepped portion 63 and bringing the side wall end portion 65 closer to the thrust plate 5 side, the fluid lubricant in the annular gap 60 and the fluid lubricants in the thrust bearing portions C and D are separated. Can be integrated with each other, and can be pushed into the thrust dynamic pressure bearing side of the fluid lubricant to improve the supply efficiency, or the fluid lubricant intake hole 64
It is possible to prevent the leakage from.

FIG. 7 shows still another embodiment according to the present invention, which has the same arrangement as that shown in FIGS. In the embodiment of FIG. 7, the thrust plate 5 side is further provided with a through hole 66 inside the supply passage 51 so as to penetrate the thrust plate 5. This allows
The pressure difference acting on the fluid lubricant retained in the dynamic pressure generating portion of the radial dynamic pressure bearing portion A can be eliminated, and stable retention of the fluid lubricant can be enhanced. Further, in FIG. 7, a concave portion 67 is provided in the peripheral wall 61 of the step portion 27 of the sleeve 4. In this case, the intake pipe 26 is located at the end of the recess 67, and this position is provided on the side of the rotor 2 (sleeve 4) in the relative rotational movement direction with respect to the shaft 2.

That is, as shown in FIGS. 8 and 9, the sleeve 4
Moves clockwise in the figure. In this embodiment, even if the gap size of the annular gap 60 is relatively small and the gap is filled with the fluid lubricant, a gap (air chamber) 68 is generated in the concave portion 67. . An intake pipe 26 communicating with the gap 68 is provided beside the gap 68. Therefore, even if the annular gap 60 is filled with the fluid lubricant by the void 68, the portion (void 68) in which the atmospheric pressure difference is always eliminated is always generated. It does not receive such acting force. Further, due to the presence of the intake pipe 26, the supply path 5
The fluid lubricant can be pushed into 0.51. At that time, since the intake pipe 26 is provided on the rotation direction side, the gap 68 can be constantly generated even when the sleeve 4 rotates at a high speed.

Here, the radial gap size of the annular gap 60 is determined by the outer peripheral end of the thrust plate 5 and the peripheral wall 6 of the sleeve 4.
1 and. The annular gap 60 has a substantially constant gap size except for the recess 67. Annular gap 6
In the case of 0, all of the fluid lubricant is filled in the gap 60 (excluding the gap 68 generated in the recess 67). Therefore, this gap size is the maximum of the gaps 98 and 99 of the taper seal structure at both ends of the motor. It is set smaller than the gap size. Therefore, similarly to the fluid lubricant intervening in each dynamic pressure bearing portion inside the electric motor, the fluid lubricant inside the annular gap 60 is not subjected to an action force that leaks to the outside of the electric motor. It should be noted that the gap size may be similarly set in the embodiments having the configurations shown in FIGS. 2 and 6 which have already been described.
This is particularly effective when the inside is filled with a fluid lubricant.

Each of the annular gaps 60 already shown has a structure defined by the sleeve 4 and the thrust cover 6,
The inner peripheral wall 61 is formed by the step portion 27 of the sleeve 4, but instead, as shown in FIGS. 10 and 11, the peripheral wall of the annular gap 60 may be formed by using the thrust cover 6 side. is there. Although not shown, an intake pipe or an intake hole may be provided on the thrust cover 6 side. Also in this case, the same effect as that of the above-described embodiment can be obtained. In FIG. 7, four through holes 66 are evenly arranged in the circumferential direction on the axial center side (inner side) of the thrust plate 5.

Each of the through holes 66 is provided in the range of the thrust bearing portions C and D, that is, in a portion outside the dynamic pressure generating portion. The through hole 66 is a communication hole for venting the radial bearing portion A side to the outside of the electric motor through the tapered gap portion 98. As a result, the radial bearing portion A
It eliminates the pressure difference on the side and does not generate the acting force of leaking the intervening fluid lubricant. The through holes 66 may be provided at least at one place. Although the embodiments of the electric motor of the present invention have been described above, the design changes or modifications can be freely made without departing from the spirit of the present invention. Needless to say, the configuration of each part used in each embodiment, the arrangement and quantity or shape of the intake pipe 26, the step part 63, the supply paths 50 and 51, and the combination thereof can be freely performed.

[0035]

Since the electric motor of the present invention has the above-mentioned structure, it has the following effects. That is, according to the electric motor of the first aspect of the present invention, the radial gap between the thrust plate 5 and the sleeve 4 is set smaller than the maximum gap of the taper seal structures 98 and 99 provided at both ends of the electric motor. Has been done. For this reason, the fluid lubricant retained in the thrust bearing portions C and D is not subjected to an acting force that leaks to the outside of the electric motor, and is retained inside the electric motor. As a result, the fluid lubricant is retained and retained also in the annular gap 60. Then, in the annular gap 60, the larger recess 6 is formed.
7 is provided on the sleeve side, and this recess 67
Since the communication hole 22 for making the air chamber pressure substantially equal to the atmospheric pressure outside the electric motor is provided in this, the pressure difference between the inside and the outside of the electric motor is eliminated in this recess 67. This prevents the fluid lubricant from being extruded from the inside of the electric motor to the outside.

According to the electric motor of the second aspect of the present invention, the communication hole 22 in the annular gap 60 is provided.
Is provided as a hollow projecting portion 26 provided so as to project inward from an inner surface defining the annular gap, and as the shaft 2 and the rotor 3 rotate relative to each other, the hollow projecting portion 26 is provided in the annular gap 60. The above-mentioned fluid lubricant is pushed into both the upper and lower end portions of the thrust plate 5, that is, the thrust dynamic pressure bearing portions C and D to form a pushing means. Then, the hollow protrusion 26 is provided with the annular gap 6
The fluid lubricant in 0 and on the side wall surface 61 of the sleeve in the annular gap 60 is integrated with the fluid lubricant to the thrust plate upper and lower end portions 33, 34 of the thrust bearing portions C, D. As a result, the fluid lubricant retained / held in the annular gap 60 is easily collected or supplied to the thrust dynamic pressure bearing portions C and D, and the exhaustion or shortage of the fluid lubricant is eliminated.

Further, according to the electric motor of claim 3, the thrust plate 5 has a hole portion 50 communicating from the outer peripheral end portion of the thrust plate 5 to the inner peripheral side of the thrust plate bearing portion.
51 are provided, and the hole portions 50, 51 serve to apply the fluid lubricant on the outer peripheral end side of the thrust plate 5 to the thrust bearing portion C,
Can be supplied to D. Further, according to the electric motor of claim 4, the outer peripheral end portion of the thrust plate 5 is provided with the groove portion 29 opening outward in the radial direction over the entire circumference,
The groove 29 captures the fluid lubricant on the outer peripheral end side of the thrust plate 5. As a result, the fluid lubricant can be easily collected or supplied to the thrust bearing portions C and D.

As described above, according to the electric motor of the present invention, leakage and depletion of the fluid lubricant interposed in the dynamic pressure bearing portion can be prevented, and highly accurate bearing support can be realized. It is possible to obtain an electric motor that can be downsized and can be rotated at high speed.

[Brief description of drawings]

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

FIG. 2 is an enlarged view of a main part of the electric motor of FIG. 1, (a) is a plan view, and (b) is a sectional view.

FIG. 3 is an enlarged cross-sectional view of a main part of the electric motor of FIG.

4 is an enlarged view of an essential part showing the operation of the electric motor of FIG.
(A) is a plan view and (b) is a sectional view.

5 is an enlarged view of an essential part showing the operation of the electric motor of FIG.
(A) is a plan view and (b) is a sectional view.

FIG. 6 is an enlarged view of a main part of an electric motor according to another embodiment of the present invention, (a) is a plan view and (b) is a sectional view.

FIG. 7 is an enlarged view of a main part of an electric motor according to still another embodiment of the present invention, (a) is a plan view and (b) is a sectional view.

8 is an enlarged view of an essential part showing the operation of the electric motor of FIG.
(A) is a plan view and (b) is a sectional view.

9 is an enlarged view of an essential part showing the operation of the electric motor of FIG.
(A) is a plan view and (b) is a sectional view.

FIG. 10 is an enlarged sectional view of an essential part of an electric motor according to still another embodiment of the present invention.

FIG. 11 is an enlarged cross-sectional view of an essential part of an electric motor according to still another embodiment of the present invention.

FIG. 12 is an enlarged perspective view of an essential part of the electric motor shown in FIGS. 7 to 9;

[Explanation of symbols]

 1 Housing 2 Shaft 3 Rotor 4 Sleeve 5 Thrust Plate 6 Thrust Cover 7 Stator 8 Rotor Magnet 10 Hub A, B Radial Dynamic Pressure Bearing C, D Thrust Dynamic Pressure Bearing

Claims (4)

[Claims] 1. A housing, a shaft member fixed to the housing, a rotor rotatably supported with respect to the shaft member, and a movement by a fluid lubricant interposed between the shaft member and the rotor. And a pressure bearing means for preventing leakage of the fluid lubricant, a tapered shape in which a radial gap between the shaft member and the rotor is increased at the both ends of the dynamic pressure bearing means in accordance with the outside of the electric motor. An electric motor having a tapered seal structure provided with a gap portion, wherein the shaft member is provided with a thrust plate projecting outward in the radial direction, and the rotor is rotatably supported by the shaft member. And a thrust cover that covers the thrust plate, a radial bearing portion is provided between the sleeve and the shaft member, and an end portion of the sleeve and the thrust A thrust bearing portion is provided between the thrust plate and the thrust plate, and between the thrust cover and the thrust plate, and a radial gap between the thrust plate and the sleeve is larger than a maximum gap of the taper seal structure. Is also set small, and an annular gap having a substantially constant gap defined by the sleeve and the thrust cover is provided on the outer peripheral end side of the thrust plate, and a larger concave portion is provided on the sleeve side in the annular gap. The recess is an air chamber, and a communication hole is provided for making the air chamber pressure in the recess substantially equal to the atmospheric pressure outside the electric motor.
An electric motor characterized in that 2. The communication hole in the annular gap is provided as a hollow protrusion that is provided so as to protrude inward from an inner surface defining the annular gap, and is associated with relative rotation between the shaft member and the rotor. The hollow protrusion serves as pushing means for pushing the fluid lubricant in the annular gap to the upper and lower end portions of the thrust plate, and the fluid in the annular gap and the side wall surface of the sleeve of the annular gap. 2. The electric motor according to claim 1, wherein a lubricant is integrated with the fluid lubricant on both upper and lower end sides of the thrust plate of the thrust bearing portion. 3. The thrust plate is provided with a hole communicating from an outer peripheral end of the thrust plate to an inner peripheral side of the thrust plate bearing portion, the hole being formed on the outer peripheral end side of the thrust plate. The electric motor according to claim 1, wherein the fluid lubricant is supplied to the thrust bearing portion. 4. The outer peripheral end portion of the thrust plate includes:
4. The electric motor according to claim 3, wherein a groove portion that opens outward in the radial direction is provided over the entire circumference, and the fluid lubricant on the outer peripheral end side of the thrust plate is captured by the groove portion.