JPH08163818A - Motor - Google Patents

Abstract

PURPOSE: To suppress deterioration of fluid lubricant at a dynamic bearing part as much as possible and to enhance the durability and reliability. CONSTITUTION: A substantially constant annular gap 60 is defined by a sleeve 4 and a thrust cover 6 on the outer circumferential end 79 side of a thrust plate 5 and a hole 81, opening radially outward, is made in the surface of the thrust plate 5 at the outer circumferential end thereof. Holes 82, 83 are also made at the positions on the surface of a shaft 2 corresponding to the positions at radial bearing parts A, B where substantially maximum dynamic pressure is produced and the holes 81, 82, 83 constitute a first communication hole 80. Furthermore, a hole 91 is made in the surface 44 at the end part of the sleeve 4 corresponding to the annular gap while a hole 92 is made at a position corresponding to the central part between the radial bearing parts A, B and the holes 91, 92 constitute a second communication hole 90.

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 called a spindle motor incorporated in a recording disk drive or the like supports a rotor hub, which is a rotating member, with high accuracy due to the nature of a drive load, and also has a high accuracy in which shake and rattling are suppressed as much as possible. Rotational support is required. 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 such as oil, and various configurations have been proposed. Particularly in a spindle motor, since there must be no rattling in the direction of the rotation axis, a thrust bearing portion is provided in addition to the radial bearing portion.

As an example of the bearing structure, for example, Japanese Examined Patent Publication Sho 63
─43606 discloses a thrust dynamic pressure bearing. Dynamic pressure generating grooves 13 and 13 'are provided on both end surfaces of a flange (thrust plate) 10 of the thrust bearing, and a housing 11 is configured to sandwich the thrust plate 10. Lubricating oil 12 is filled between the thrust plate 10 and the housing 11, and the two rotate relative to each other in accordance with the dynamic pressure generation pressure.

In recent years, the size and capacity of the above drive devices have been reduced, and the demands on electric motors have become more and more stringent. That is, in addition to the downsizing of the electric motor itself, the temperature of the surrounding environment rises remarkably due to the high density of mounted parts, and the influence on the electric motor has become high. As a characteristic of the electric motor, high-speed rotation is required, and the conventional motor has several thousand r.s.r. p. m to 10,000 r. p. High-speed rotation of m or more has become necessary.

[0005]

However, in the electric motor having the above-mentioned structure, the dynamic pressure bearing is caused by the temperature rise around the electric motor or the temperature rise of heat generated from the heat-generating components (eg armature) inside the motor or the bearing portion. The lubricating oil in the part is likely to deteriorate. That is, the deterioration of the lubricating oil is promoted.
In addition, with the start / stop operation of the electric motor, the lubricating oil is polluted by the abrasion powder generated as a result of the inevitable abrasion particularly in the thrust bearing portion, and the deterioration is similarly promoted. When such deterioration of the lubricating oil progresses, it becomes difficult to maintain high-precision rotary bearing support for a long time, and continuous operation by high-speed rotation becomes difficult. Therefore, in order to improve the durability and reliability of the electric motor, it is necessary to take some measures.

The present invention has been made in view of the above-mentioned problems existing in the prior art. The problem is that the heat generation inside and outside the electric motor and the start / stop operation are performed. However, the deterioration of the fluid lubricant interposed in the dynamic pressure bearing portion can be suppressed as much as possible, and thus the initial characteristics can be maintained for a long time in an environment such as long-term continuous operation or high-speed rotation. It is to provide an electric motor with high durability and reliability.

[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. An electric motor comprising: a hydrodynamic bearing means that is interposed between the shaft member and the rotor and is made of a fluid lubricant; the shaft member is provided with a thrust plate that projects radially outwardly around the entire circumference; The rotor is a sleeve rotatably supported by the shaft member,
A thrust cover covering the thrust plate;
A plurality of radial bearing portions are provided between the sleeve and the shaft member, and thrust bearing portions are respectively provided between the end portion of the sleeve and the thrust plate and between the thrust cover and the thrust plate. 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; the outer peripheral end surface of the thrust plate has a radial outer surface. A hole portion that is opened toward one side is provided, and on the surface of the shaft member, at a corresponding portion where substantially the maximum dynamic pressure of the plurality of radial bearing portions is generated,
Hole portions are respectively provided; the hole portions in the shaft member and the thrust plate are configured as first communication holes that communicate with each other through the inside of the thrust plate and the shaft member respectively; A hole is provided in the end surface of the corresponding sleeve, and between the inner peripheral surfaces of the sleeve facing the shaft member, the maximum dynamic pressure of the radial bearing is generated. A hole is provided at a portion corresponding to the center of the sleeve, and the both holes of the sleeve are configured as a second communication hole that communicates with each other through the inside of the sleeve; , The first communication hole serves as a fluid lubricant return path through which the fluid lubricant flows from the radial bearing portion to the thrust bearing portion, while the second communication hole defines the fluid lubrication There is obtained by the backward fluid lubricant reflux flowing from the thrust bearing portion to the radial bearing portion.

Another electric motor of the present invention includes a housing, a shaft member fixed to the housing, a rotor rotatably supported with respect to the shaft member, and an interposition between the shaft member and the rotor. And a dynamic pressure bearing means by means of a fluid lubricant, wherein the shaft member is provided with a thrust plate projecting outward in the radial direction, and the rotor is rotatably attached to the shaft member. A support sleeve and a thrust cover for covering the thrust plate; a plurality of radial bearing portions are provided between the sleeve and the shaft member, and between the end portion of the sleeve and the thrust plate; and Thrust bearing portions are provided between the thrust cover and the thrust plate, respectively. The three outer peripheral ends of the thrust plate are provided with the three thrust bearing portions. And annular gap substantially constant gap defined by said thrust cover is provided; the opposite surfaces of the thrust cover side of the thrust plate, corresponding to the inner peripheral edge portion of the thrust bearing portion,
A hole opening to the thrust cover side is provided; a hole is provided in a portion of the surface of the shaft member where the maximum dynamic pressure of the radial bearing portion is substantially generated; Each of the holes in the member and the thrust plate is configured as a first communication hole that communicates with the inside of the thrust plate and the shaft member respectively; the end surface of the sleeve corresponding to the annular gap. In the inner peripheral surface of the sleeve facing the shaft member, a portion corresponding to the center portion between the radial bearing portions where substantially maximum dynamic pressure is generated, A hole is provided; both holes of the sleeve are configured as a second communication hole that communicates with each other through the inside of the sleeve; Is the fluid lubricant recirculation outward path through which the fluid lubricant circulates from the radial bearing portion to the thrust bearing portion, while the second communication hole is formed by the fluid lubricant from the thrust bearing portion to the radial bearing portion. It is used as a return path for the fluid lubricant circulating to the.

Further, according to the electric motor of the present invention, in each electric motor having the above-mentioned structure, foreign matter in the fluid lubricant is present in the first communication hole and / or the second communication hole or in the opening hole portion. Alternatively, it is desirable to install a filter member for filtering impurities and the like.

[0010]

According to the electric motor of the present invention, the hole portion on the shaft member side in the first communication hole is provided corresponding to the portion of the radial bearing portion where substantially the maximum dynamic pressure is generated. For this reason, as the electric motor is driven to rotate, the pressure of the fluid lubricant becomes 1 atm or more due to the generated pressure of the radial dynamic pressure, and a part of the fluid lubricant acts so as to be pushed into the first communication hole. Then, the gas flows through the first communication hole to the end portion side of the thrust plate. This fluid lubricant stays in the annular gap on the end portion side of the thrust plate and is easily communicated and supplied to the thrust bearing portion by the capillary phenomenon. Then, the fluid lubricant which is supplied to the thrust bearing portion and which has become excessive or cannot be retained is retained in the annular gap.

On the sleeve inner peripheral surface side, the radial bearing portion is formed in the sleeve end portion corresponding to the annular gap and the second communicating hole having an opening hole portion in each of the sleeve inner peripheral surface corresponding to the shaft member. The negative pressure of 1 atm or less is acting as a reaction due to the generation of the dynamic pressure. This is because the holes are provided corresponding to the centers of the radial bearing portions where the maximum dynamic pressure is generated. Therefore, a part of the fluid lubricant staying in the annular gap receives an acting force so as to be sucked in the opening hole portion, and the fluid lubricant flows back to the radial bearing portion side through the second communication hole. Become.

That is, the first communication hole serves as a fluid lubricant return path through which the fluid lubricant flows from the radial bearing portion to the thrust bearing portion, while the second communication hole causes the fluid lubricant to flow from the thrust bearing portion to the radial direction. It acts as a return path for the fluid lubricant circulating to the bearing portion. As a result, the fluid lubricant circulates evenly inside the electric motor through the first and second communication holes. Therefore, the fluid lubricant is not partially heated to the temperature rise of the heat generated inside and outside the electric motor, and is evenly circulated and radiated, so that the temperature rise of the fluid lubricant is suppressed.
Further, even if abrasion powder is generated due to the start / stop operation, the contamination is homogenized by the circulation of the fluid lubricant without being partially contained or retained in the fluid lubricant. As a result, alteration / deterioration of the fluid lubricant can be reduced as much as possible, the initial characteristics can be maintained for a long time in an environment such as long-term continuous operation or high-speed rotation, and durability and reliability can be improved.

According to the above another electric motor, one opening hole of the first communication hole is provided on the thrust cover side of the thrust plate, and the hole is the inner peripheral edge of the thrust bearing portion. It is positioned corresponding to the department. Therefore, the fluid lubricant from the radial bearing portion is supplied to the thrust bearing portion on the thrust cover side of the thrust plate in the first communication hole serving as the fluid lubricant return path, and
Similarly, through the annular gap, it becomes the fluid lubricant recirculation return path.
Is distributed to the communication hole. According to the electric motor of the present configuration, durability and reliability can be improved by the same action as the above electric motor, and in the electric motor of the present configuration, mainly to the thrust cover side thrust bearing portion where the use posture of the electric motor is the upper side, First, the fluid lubricant is supplied. Therefore, first, a stable fluid lubricant can be supplied to the thrust bearing portion on the upper side of the thrust plate, which tends to flow out due to gravity, and smoother circulation of the fluid lubricant can be realized.

Further, for each electric motor having the above structure, a filter member for filtering foreign matters, impurities, etc. of the fluid lubricant in the middle of or in the opening of the first communication hole and / or the second communication hole. By mounting the, the fluid lubricant is prevented from being contaminated, and the deterioration and deterioration of the fluid lubricant is further reduced.

[0015]

Embodiments of an electric motor according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is an overall cross-sectional view of an electric motor for rotationally driving a recording disk such as an optical / magnetic disk. FIG. 2 is an enlarged cross-sectional view mainly showing a portion where the rotor 3 is rotatably supported on the shaft 2 by the dynamic pressure bearing of FIG. 3 shows the members in FIG. 1, (a) is a side view showing a state in which the shaft 2 and the thrust plate 5 are fixed, (b) is a plan view seen from the upper end 33 side of the thrust plate 5,
Similarly, (c) is a plan view seen from the lower end portion 34 side of the thrust plate 5, and (d) is a sectional view of the sleeve 4. In these drawings, the same numbers are given to the same members and parts.

1 to 3, the housing 1 is made of an aluminum alloy, and a boss portion 16 formed so as to bulge upward (inside the electric motor) is provided at the center of the housing 1. A hole portion 15 is provided in the center of the boss portion 16, and a tubular bush 70 is fitted and fixed inside the hole portion 15. The bush 70 is formed of a steel material or the like. The lower end of the shaft 2 is fitted and fixed in the hole 71 of the bush 70. The bush 70 is an intervening member interposed between the housing 1 and the shaft 2, and adjusts the dimensions of the housing 1 and the shaft 2 and secures the fixed rigidity of the shaft 2 fitted to the aluminum alloy housing 1. It is for doing.

The shaft 2 is mounted substantially perpendicular to the mounting surface 72 of the housing 1. The shaft 2 is formed of, for example, an iron-based alloy or the like, and the outer peripheral portion on the upper end side is slightly reduced in diameter (reduced diameter portion 73),
The disk-shaped thrust plate 5 is externally fitted and fixed to the reduced diameter portion 73. Thrust plate 5 is shaft 2
Is formed substantially at a right angle with respect to the longitudinal (axial) direction thereof, and the surfaces of the upper and lower end portions 33 and 34 thereof are formed substantially parallel to each other.

The rotor 3 rotatably supported by 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, stainless steel which is a magnetic material, and a recording disk (not shown) as a rotational load is externally fitted and attached to the outer peripheral portion 49 of the hub 10. The flange 41 of the hub 10 is formed so as to project outward to receive the recording disk. The recording disk is integrally fixed to the hub 10 by a well-known clamp means (not shown).

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. The thrust cover 6 is mounted on the stepped portion 27 of the expanded diameter portion 25 of the sleeve 4. The thrust cover 6 has a ring shape, the outer peripheral portion of which is fitted on the upper inner peripheral side 74 of the sleeve 4 and is tightly fixed to the sleeve 4 by caulking the sleeve upper end portion 32. Inner peripheral portion 5 of thrust cover 6
7 is opposed to the outer peripheral portion 19 (reduced diameter portion 73) of the shaft 2 with a slight gap. These sleeve 4, hub 1
0 and an integral member including a thrust cover 6 fixed to the sleeve 4 are rotatably supported with respect to the shaft 2.

On the boss portion 16 of the housing 1, a step portion 17 is formed on the upper portion of the 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 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, the rotor 3 (hub 10) is rotationally driven by the electromagnetic interaction between the rotor magnet 8 and the stator 7.

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 form the radial dynamic pressure bearing portions A and B, a fluid lubricant is interposed, and at the corresponding portion of the inner peripheral portion 31 of the sleeve 4,
As shown in FIG. 3D, herringbone-shaped dynamic pressure generating grooves 75 and 76 formed at predetermined intervals in the circumferential direction are provided over the entire circumference. In addition, these dynamic pressure generating grooves 75, 7
6 is an alternative to the shaft 2 facing the sleeve 4 side.
It may be provided on the outer peripheral portions 47, 48 side.

On the other hand, the lower end portion 52 of the thrust cover 6 and the thrust plate 5 facing the lower end portion 52 in the axial direction (vertical direction).
Upper end 33 of the thrust plate 5 and lower end 34 of the thrust plate 5
Of the sleeve 4 (of the peripheral wall 24) facing in the same direction as
The upper end portion 44 constitutes thrust dynamic pressure bearing portions C and D. Since the thrust dynamic pressure bearing portions C and D are configured,
The fluid lubricant is interposed, and the upper and lower end portions 33, 34 of the thrust plate 5 are provided in FIGS. 3B and 3C.
As shown in, the herringbone-shaped dynamic pressure generating grooves 77 and 78 formed at predetermined intervals in the circumferential direction are provided over the entire circumference. In addition, the dynamic pressure generating grooves 77 and 78 may be formed in a spiral shape, although not shown. Further, the dynamic pressure generating grooves 77, 78 are respectively formed in the thrust plate 5
Instead of being formed on the side, it may be provided on the lower end portion 52 of the thrust cover 6 and the upper end portion 44 side of the sleeve 4 which face the thrust cover 6 respectively. Alternatively, a combination thereof may be used.

On the outer peripheral end 79 side of the thrust plate 5, the thrust cover 6 (lower end portion 52) and the sleeve 4 (inner peripheral portion 61 of the step portion 25, upper end portion 44 of the peripheral wall 24) are defined. An annular gap 60 that is formed over the entire circumference of the thrust plate 5 is provided. The outer peripheral end portion 79 of the thrust plate 5 is provided with an annular groove 29 that is open to the outside over the entire circumference, and the annular groove 29 has a shape in which the outer peripheral end is the maximum opening and the shape is narrowed toward the inside. I am in a shape.

Further, at the outer peripheral end 79 of the thrust plate 5, a hole 81 is formed in a part of the annular groove 29 so as to open radially outward. The hole 81 forms an opening on the thrust plate side of the communication passage 80 that communicates with the center of the inner shaft of the shaft 2. As shown in FIG. 2, the communication passage 80 (first communication hole) communicates with the axial center of the shaft 2 in the axial direction, and one of the branched portions opens at the outer peripheral portion 47 of the shaft 2 (hole portion). 82) and the other is formed so as to open (hole 83) in the outer peripheral portion 48 of the shaft 2. In addition, the through hole 84 formed on the upper end side of the shaft 2 has the communication passage 80.
This through hole 8 is generated by processing to form
4 is inserted with a closing member 85 for sealing it. Various metal materials and resin materials can be used for the closing member 85, and the through holes 84 may be filled by press fitting, bonding, or the like.

Holes 82 and 83 formed in the shaft 2
Are both the dynamic pressure generating central portions of the radial dynamic pressure bearing portions A and B, that is, the portions where the dynamic pressure generating pressure is the maximum (in the illustrated example, the portions 86 in the dynamic pressure generating grooves 75 and 76 in FIG. 3D). , 8
(Site corresponding to 7). Therefore, when the electric motor is rotationally driven and the rotor 3 is relatively rotated, a part of the fluid lubricant interposed in the radial bearing portions A and B flows into the holes 82 and 83 and passes through the communication passage 80, Through the hole 81 of the outer peripheral end portion 79 of the thrust plate. The flow of this fluid lubricant is shown by the arrow in FIG. This is because the dynamic pressure generation pressure of the dynamic pressure bearing portions A and B becomes larger than the atmospheric pressure, that is, 1 atmospheric pressure or more, while the thrust plate outer peripheral end 79 side is substantially 1 atmospheric pressure, so the fluid lubricant is the thrust plate. Receives acting force to move to side 5.

The holes 82 and 83 make use of a part of the dynamic pressure generation pressure generated in the dynamic pressure bearing portions A and B to cause the fluid lubricant to flow in. Therefore, in order to obtain the dynamic pressure generating pressure for sending the fluid lubricant to the thrust plate 5 side in advance, in addition to the dynamic pressure generating pressure necessary for maintaining the original bearing support, the dynamic pressure bearing portions A and B are provided in advance. The generated pressure is set. In order to send the fluid lubricant having an appropriate pressure to the holes 82, 83 side without damaging the dynamic pressure generation pressure to the dynamic pressure bearing portions A, B, the communication passage 80 has an appropriate flow resistance for the fluid lubricant. Need to have.

In this embodiment, the cross-sectional area of the communication passage 80 is preliminarily drilled so as to correspond to a predetermined size. Communication passage 80
In the case where the cross-sectional area of is larger than a predetermined value for the convenience of processing, the diameter of the hole portion 82, 83 or 81 which is the opening portion of the communication passage 80 may be reduced to provide a "throttle". . The “drawing” can be easily formed by plastic deformation processing or the like. Further, as shown in FIG. 4, the “diaphragm” is the diaphragm members 102 and 103 whose aperture diameter is reduced to a predetermined aperture area.
It can also be fitted and fixed to the shaft 2. (In the drawings shown below, the same parts and members as those of the electric motor of FIG. 1 are denoted by the same reference numerals.) Further, in FIG. 4, the throttle member 101 is fitted in the opening on the thrust plate 5 side. It may be fixed. A combination of these can also be provided. In addition, the opening shape is circle or arc,
By selecting various shapes such as a square and a star, the area can be substantially changed and adjusted. On the other hand, in contrast to this, in the present embodiment, one communication passage 80 is provided, but in order to increase the cross-sectional area, it is possible to use a plurality of passages for the shaft 2 as an example.
It may be arranged in the circumferential direction of. Further, as shown in FIG. 5, the screw 10 is inserted into the through hole 84 in the middle of the communication passage 80.
4 can be screwed on and can be arbitrarily adjusted depending on the degree of advance of the screw 104. In this case, after adjustment with the screw 104, the through hole 84 is sealed with the closing member 105.

The fluid lubricant sent from the radial bearing portions A and B flows out from the hole portion 81 of the thrust plate 5. Since the hole 81 is provided with the annular groove 29, the fluid lubricant from the hole 81 is transmitted to the annular groove 29 by the capillary phenomenon and the surface tension, and easily flows out to the thrust plate outer peripheral end 79 side. . Then, it is retained and held in the gap between the sleeve inner peripheral portion 61 and the thrust plate outer peripheral end portion 79, that is, in the annular gap 60 soon. The gap (radial direction) between the outer circumferential end portion 79 of the thrust plate and the inner circumferential portion 61 (of the step portion 27) of the sleeve 4 in the annular gap 60 is such that the fluid lubricant acts by a capillary phenomenon. ing. Therefore, the fluid lubricant retained and retained in the annular gap 60 is soon supplied to both thrust bearing portions C and D.

The annular gap 60 is provided with a hole 91 that opens to the upper end 44 of the expanded diameter portion 25 of the sleeve 4. The hole 91 extends downward from the peripheral wall 24 of the sleeve 4 and communicates with a hole 92 formed in the sleeve inner peripheral portion 31. A communication passage 90 (second communication passage) is constituted by the holes 91 and 92. The hole 92 is
Substantially an intermediate portion of the radial bearing portions A and B in the sleeve inner peripheral portion 31 (a central portion between the radial bearing portions A and B).
It is provided in the part 93 located at. The intermediate portion 93 includes both radial bearing portions A, which accompany the rotational driving of the electric motor.
Due to the dynamic pressure generation pressure of B, the reaction produces a negative pressure of 1 atm or less. For this reason, the fluid lubricant retained and retained in the annular gap 60 is not supported by the hole 9 as shown by the arrow in FIG.
1 receives an acting force so as to flow to the hole portion 92 through the communication passage 90, and is soon supplied to both radial bearing portions A and B.

Similar to the communication passage 80, in the communication passage 90 as well, the cross-sectional area can be adjusted to adjust the flow of the fluid lubricant, and the holes 91, 9 corresponding to the openings thereof.
It is possible to provide a “diaphragm” in 2 and select various shapes for the cross-sectional shape and the opening shape. Further, a plurality of communication passages 90 may be provided in the sleeve 4. When a plurality of communication passages 90 are provided in the sleeve 4, it is desirable that they are evenly arranged in the circumferential direction in consideration of rotational dynamic balance.

Thus, as is clear from the above, the communication passages 80 and 90 form a circulation passage for circulating the fluid lubricant interposed in the dynamic pressure bearing portion inside the electric motor.
The communication passage 80 serves as a return path for circulating the radial bearings A and B to the thrust bearings C and D by the rotational driving of the electric motor, and the communication passage 90 functions from the thrust bearings C and D to the radial bearings A and B. It serves as a return path for circulation to. Therefore, the fluid lubricant is not partially heated by the temperature rise of the heat generated inside and outside the electric motor, and is evenly circulated and radiated, so that the temperature rise of the fluid lubricant is suppressed.

In the illustrated example of this embodiment, the radial bearing portion has a pair of bearing means at two locations A and B, but it is also possible to deal with radial bearing portions at three or more locations. At that time, a hole portion (the hole portion 82,
(Corresponding to 83) is provided corresponding to the part where each dynamic pressure generation pressure is maximum. Further, a hole portion (corresponding to the hole portion 92 of this embodiment) serving as an opening outlet of the return return path is provided in the center portion between the respective portions. Further, it is possible to deal with the case where the radial bearing portion is formed at one place. At that time, if the outflow hole 92 of the communication passage 90 serving as the return return path is set so as to be positioned in the vicinity of the end of the dynamic pressure generating groove of the radial bearing portion, a negative pressure action can be easily obtained.

Due to the rise in temperature of heat generated from the stator 7,
The internal temperature of the electric motor is raised, and the electric motor is frequently started and stopped repeatedly, so that the thrust bearings C and D and the thrust plate 5 are worn (which is inevitably generated at the time of starting and stopping) to generate heat. Occurs. However, according to this configuration, temperature alteration / deterioration of the fluid lubricant due to such temperature rise is prevented as much as possible, and the temperature rise distribution of heat generation inside the electric motor is homogenized to increase the temperature rise of the electric motor as a whole. Can be reduced.

Further, even if abrasion powder is generated by the thrust plate 5 and the sleeve 4 due to the start / stop operation, the fluid powder 9 is circulated by the circulation of the fluid lubricant 9 without being partially contained or retained in the fluid lubricant 9. The pollution is homogenized. As a result, alteration / deterioration of the fluid lubricant is reduced as much as possible,
The initial characteristics can be maintained for a long time in an environment such as long-term continuous operation or high-speed rotation, and durability and reliability can be improved.

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. Outer peripheral portion 19 of shaft 2 (reduced diameter portion 73)
An annular groove 36 is provided in the inner surface of the thrust cover 6, and an annular gap between the annular groove 36 and the annular groove 88 (of 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. For this reason,
The fluid lubricant in the dynamic pressure generator goes to the outside of the motor (to the upper side of the figure)
Even if an attempt is made to leak, these two gaps prevent leakage due to the surface tension acting on the fluid lubricant.

In particular, the gap 98 between the thrust plate 5 and the tapered portion 62 is constructed so as to gradually increase toward the outside of the electric motor. Therefore, even if the fluid lubricant moves or fluctuates, the fluid lubricant can be reliably held at the equilibrium portion corresponding to the predetermined gap width due to the surface tension / capillary phenomenon. That is, the taper portion 62 has a sealing function for preventing leakage of the fluid lubricant. And further, the annular groove 3
With 6,88, leakage can be prevented more effectively. It should be noted that these parts 57, 6 of the thrust cover 6 are
The leakage of the fluid lubricant can be further prevented by applying an oil repellent agent that repels the fluid lubricant to the outer peripheral portion 19 of the shaft 2 and the annular groove 36.

On the other hand, a radial dynamic pressure bearing portion B is provided below the sleeve 4 shown in FIG. 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 outer peripheral portion 19 of the shaft is provided with the taper portion 40 on the lower end side thereof, and the gap with the inner peripheral portion 31 of the sleeve 4 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). The leakage prevention effect can be enhanced by applying an oil repellent agent that repels the fluid lubricant to the portions of the annular grooves 37 and 43.

FIG. 6 shown next is an electric motor showing another embodiment. A feature of the electric motor in FIG. 6 is that a filter 94 for filtering the fluid lubricant is mounted in the passage 80. The filter 94 is intended to separate and remove impurities such as abrasion powder contained in the fluid lubricant, and for example, porous metal, ceramics, fibers, and metal net can be used. Therefore, as compared with the embodiment of FIG. 1, the deterioration and deterioration of the fluid lubricant is further suppressed, and the initial characteristics can be maintained for a long time in an environment such as long-term continuous operation or high-speed rotation, and durability. And the reliability can be further improved. The filter 94 of FIG.
Since the upper end through hole 84 of the communication passage 80 is expanded,
Easy to put on. The upper end of the shaft has a closing member 95.
It is sealed with. Further, in the present embodiment, the filter 94 is provided on the side of the shaft 2 which is the fixing member, so that the filter 94 can be easily mounted and does not directly affect the rotation characteristics of the electric motor.

Further, the filter 94 may be made of the above-mentioned foreign substance removing material or member, or may be made of activated carbon or chemically activated substance to remove fine substances or denatured components of the fluid lubricant. It goes without saying that it is possible.

FIG. 7 shows an electric motor according to still another embodiment. In FIG. 6, the filter 94 is provided in the shaft 2 side, that is, in the return outward passage 80 of the fluid lubricant, whereas in FIG. In the embodiment, the filter 94 is provided on the sleeve 4 side, that is, on the return return side communication passage 90.
Specifically, the upper end portion 4 of the expanded diameter portion 25 of the sleeve 4
It is installed on the 4 side. Further, in FIG. 8, it is provided in the middle of the communication passage 90, and in FIG. 9, it is provided in the opening portion on the sleeve inner peripheral portion 31 side. With these, the filter 94 can be attached to any part or position, and the same effect can be obtained. Needless to say, filters may be attached to both the communication passages 80 and 90, and a combination of these may be set freely.

In the electric motor shown in FIGS. 1 to 9, the hole 81, which is the opening outlet of the communication passage 80, is provided on the outer peripheral end 79 side of the thrust plate 5. In the electric motor of another embodiment shown in FIG. 10, the hole 99 corresponding to the hole 81 is formed.
Are provided on the upper end portion 33 side of the thrust plate 5. The hole 99 is positioned on the shaft 2 side of the upper end portion 33, that is, on the inner peripheral edge side of the thrust dynamic pressure bearing portion C (the thrust plate upper end portion 33 corresponding to the tapered portion 62 of the thrust cover 6). There is. Therefore, the fluid lubricant from the radial bearing portions A and B is sent out to the hole portion 99 of the thrust plate 5 through the communication passage 80 which serves as the fluid lubricant return path. The opening of the hole 99 is a gap 98 formed by the thrust plate 5 (upper end 33) and the thrust cover 6 (tapered portion 62). This gap 98 prevents the fluid lubricant from leaking to the outside. (For use) This is a part that forms a seal function part and holds the fluid lubricant. Therefore, the fluid lubricant sent out from the hole portion 99 is
Is temporarily held in the thrust bearing portion C.

The fluid lubricant from the thrust bearing portion C is urged from the upper end portion 33 of the thrust plate 5 to the peripheral wall 61 or directly to the gap 6 by the centrifugal force of the sleeve 4 or other acting force.
Stay at 0. Then, while the fluid lubricant is supplied to the thrust bearing portion D, it is circulated through the opening 91 of the sleeve 4 to the communication passage 90 which serves as a return path. Therefore, also in the electric motor of this embodiment, durability and reliability can be improved by the same operation as that of the electric motor of FIGS. In this embodiment, the fluid lubricant is first supplied to the thrust bearing portion C on the thrust cover 6 side, where the use posture of the electric motor is the upper side. Therefore, a stable fluid lubricant can be supplied to the upper side of the thrust plate 5 that easily flows out due to gravity, and smoother circulation of the fluid lubricant can be realized.

Since the hole 99 is provided corresponding to the gap 98 of the thrust plate upper end portion 33, it does not engage with the dynamic pressure generating groove 77 on the thrust plate upper end portion 33. Therefore, there is no influence on the dynamic pressure bearing support of the thrust dynamic pressure bearing portion C.

FIG. 11 shown next shows still another embodiment, of which (a) is a plan view of the electric motor as seen from above, showing the state where the thrust cover 6 is removed. And (b) is a partial cross-sectional view thereof, and (c) is a perspective view of the state in which the thrust cover 6 is removed. Figure 11
In addition to the above-described embodiments, or in combination thereof, the following embodiments can be further used in combination. And FIG.
In FIG. 10, the communication passages 80 and 90 used in FIGS.
Although not shown for the sake of convenience, the following description will be given on the assumption that it is actually configured.

In FIG. 11, the thrust plate 5 is provided with holes 50, 51 which communicate with the annular groove 29 from the thrust dynamic pressure bearing portions C, D of the upper and lower end portions 33, 34. The hole 51 is provided so as to penetrate the thrust plate 5 in the axial direction, and the hole 50 is provided so as to penetrate from the hole 51 to the outer peripheral end 79 side substantially in parallel with the thrust plate 5. Further, a through hole 66 is provided on the shaft 2 side of the thrust plate 5.

On the other hand, on the side of the outer peripheral end portion 79 of the thrust plate on the sleeve 4 side, the annular gap 6 having a small gap width (to the extent that the fluid lubricant is sufficiently retained by the capillary phenomenon).
In addition to 0, the intake pipe 26 is provided in a 180-degree rotational symmetry. The sleeve inner peripheral portion 61 corresponding to the intake pipe 26 is further provided with an arcuate recess 67.
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 shaft 2 in the relative rotational movement direction of the rotor 3 (sleeve 4).

According to this embodiment, if the electric motor is driven to rotate at high speed or the electric motor is impacted, the fluid lubricant is scattered from the respective dynamic pressure generating portions to the annular gap 60, or the internal portion for defining the annular gap is defined. Even if it leaks to the peripheral wall 61 or the end portion 44 of
It is received and held 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 fluid lubricant scattered and leaked into the annular gap 60 does not leak to the outside of the electric motor through the opening 22 because the opening 22 of the intake pipe 26 projects inward of the gap space.

As shown in FIG. 11A, the sleeve 4 rotates and relatively moves as shown in the figure. In this embodiment, even if the gap size of the annular gap 60 is relatively narrow and the gap is filled with the fluid lubricant 9, the void 68 is formed in the recess 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 gap 68, the portion where the pressure difference is always eliminated (the gap 6).
Since 8) is always generated, it is not affected by the action force that moves the fluid lubricant even when the temperature changes. Further, due to the presence of the intake pipe 26, the supply path 50,
The fluid lubricant can be pushed into 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.

Therefore, the fluid lubricants retained in the thrust dynamic pressure bearing portions C and D are 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 acting force of the fluid lubricant moving. In the present embodiment, the through hole 6 penetrating the thrust plate 5 is provided inside the supply passage 51 on the thrust plate 5 side.
Since 6 is further provided, 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 the stable retention of the fluid lubricant can be further enhanced. As described above, the embodiment shown in FIG.
By using the electric motor in combination with or by combining these electric motors, it is possible to obtain an electric motor in which the fluid lubricant can be used stably and excellent bearing support can be realized in terms of both reliability and durability.

Although the embodiment of the electric motor of the present invention has been described above, the design change or modification can be freely made without departing from the gist of the present invention. For example, the annular gap 60 already shown in the embodiment has a structure defined by the sleeve 4 and the thrust cover 6, and the inner peripheral wall 61 is formed by the step portion 27 of the sleeve 4, but instead of this, It is also possible to use the peripheral wall of the annular gap 60 on the thrust cover 6 side. In addition, the groove shape, arrangement, and quantity of the dynamic pressure bearing portion can be arbitrarily selected. Although illustration is omitted, in FIG. 11, the intake pipe 26 or the intake hole 22 may be provided on the thrust cover 6 side. Further, instead of the intake pipe 26, it may have an integrally formed intake hole 22. Furthermore, in this embodiment,
Although the thrust plate 5 and the shaft 2 are formed of separate members, they may be integrally formed.

[0051]

Since the electric motor of the present invention has the above-mentioned structure, it has the following effects. That is, claim 1 of the present invention
According to the electric motor corresponding to, the communication hole 80 serves as a fluid lubricant recirculation outward path in which the fluid lubricant flows from the radial bearing portions A and B to the thrust bearing portions C and D, while the communication hole 90
The fluid lubricant is used as a return path for the fluid lubricant to flow from the thrust bearing portions C and D to the radial bearing portions A and B. As a result, the fluid lubricant circulates evenly inside the electric motor through the communication holes 80 and 90. Therefore, the fluid lubricant is not partially heated to the temperature rise of the heat generated inside and outside the electric motor, and is evenly circulated and radiated, so that the temperature rise of the fluid lubricant is suppressed. Further, even if abrasion powder is generated due to the start / stop operation, the contamination is homogenized by the circulation of the fluid lubricant without being partially contained or retained in the fluid lubricant. As a result, alteration / deterioration of the fluid lubricant can be reduced as much as possible, the initial characteristics can be maintained for a long time in an environment such as long-term continuous operation or high-speed rotation, and durability and reliability can be improved.

According to the electric motor of the second aspect of the present invention, one opening hole 99 of the communication passage 80 is provided on the thrust cover 6 side of the thrust plate 5, and the hole 99 is the thrust bearing. It is positioned corresponding to the inner peripheral edge of the portion C. Therefore, the fluid lubricant from the radial bearings A and B is supplied to the thrust cover 6 side of the thrust plate 5 in the communication passage 80 serving as the fluid lubricant return path, and similarly passes through the annular gap 60, The fluid lubricant is circulated to the communication passage 90 which serves as a return path. According to the electric motor of this configuration, durability and reliability can be improved by the same action as that of the electric motor of claim 1, and in the present configuration, particularly, the thrust cover 6 side in which the use posture of the electric motor is mainly on the upper side. First, the fluid lubricant is supplied to the thrust bearing portion C. Therefore, first, stable fluid lubricant can be supplied to the thrust bearing portion C on the upper side of the thrust plate 5 that easily flows out due to gravity, and smoother circulation of the fluid lubricant can be realized.

Further, according to claim 3, in the middle of the communication passage 80 and / or the communication passage 90 or in the opening hole portion,
By mounting the filter member 94 that filters the fluid lubricant 9, the fluid lubricant 9 is prevented from being contaminated, and the alteration / deterioration of the fluid lubricant is further reduced.

[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 shown in FIG.

3 is an enlarged view of a main part of the electric motor shown in FIG. 1, where (a) is a plan view, (b) is a sectional view, and (c) is a perspective view.

FIG. 4 is an enlarged sectional view of an essential part of an electric motor according to another embodiment of the present invention.

FIG. 5 is an enlarged sectional view of an essential part of an electric motor according to still another embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a main part of an electric motor according to still another embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view of a main part of an electric motor according to still another embodiment of the present invention.

FIG. 8 is an enlarged cross-sectional view of a main part of an electric motor according to still another embodiment of the present invention.

FIG. 9 is an enlarged sectional view of an essential part of an electric motor according to still another embodiment of the present invention.

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 view of a main part of an electric motor according to still another embodiment of the present invention, in which (a) is a plan view and (b) is a sectional view.
(C) is a perspective view.

[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

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[Procedure amendment]

[Submission date] April 7, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

FIG. 3 is an enlarged view of a main part of the electric motor shown in FIG. 1, where (a) is a side view.
Plan view, (b) is a plan view, (c) is a plan view, and (d)
Is a sectional view .

Claims (3)

[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. In the electric motor including pressure bearing means, the shaft member is provided with a thrust plate that projects radially outwardly over the entire circumference, and the rotor includes a sleeve rotatably supported by the shaft member, A thrust cover covering the thrust plate, a plurality of radial bearing portions are provided between the sleeve and the shaft member, between the end portion of the sleeve and the thrust plate, and between the thrust cover and the thrust plate. Thrust bearing portions are respectively provided between the sleeve and the thrust cover on the outer peripheral end side of the thrust plate. An annular gap having a substantially constant gap defined by the above, and a hole opening outward in the radial direction on the outer peripheral end surface of the thrust plate. Holes are provided in corresponding portions of the bearing portion where substantially the maximum dynamic pressure is generated, and the holes in the shaft member and the thrust plate are respectively inside the thrust plate and the shaft member. Is formed as a first communication hole that communicates with each other via the end surface of the sleeve that corresponds to the annular gap, and a hole is provided in the sleeve. A hole portion is provided at a portion corresponding to a center portion between the radial bearing portions where substantially maximum dynamic pressure is generated, and the both hole portions of the sleeve are inside the sleeve. Fluid lubrication in which the fluid lubricant flows from the radial bearing portion to the thrust bearing portion through the first communicating hole when the rotor is rotationally driven. The electric motor is characterized in that it is an outward flow path of the agent, and the second communication hole is a return path of the fluid lubricant in which the fluid lubricant flows from the thrust bearing portion to the radial bearing portion. 2. 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. In the electric motor including pressure bearing means, the shaft member is provided with a thrust plate that projects radially outwardly over the entire circumference, and the rotor includes a sleeve rotatably supported by the shaft member, A thrust cover covering the thrust plate, a plurality of radial bearing portions are provided between the sleeve and the shaft member, between the end portion of the sleeve and the thrust plate, and between the thrust cover and the thrust plate. Thrust bearing portions are respectively provided between the sleeve and the thrust cover on the outer peripheral end side of the thrust plate. An annular gap having a substantially constant gap defined by the above is provided, and an opposing surface of the thrust plate on the thrust cover side is opened toward the thrust cover side in correspondence with the inner peripheral edge of the thrust bearing portion. Holes are provided in the surface of the shaft member, and holes are respectively provided in corresponding portions of the radial bearing part where substantially maximum dynamic pressure is generated, and in the shaft member and the thrust plate. Each of the hole portions is configured as a first communication hole that communicates with each other through the inside of the thrust plate and the shaft member, and the hole portion is formed on the end surface of the sleeve corresponding to the annular gap. Of the inner peripheral surface of the sleeve facing the shaft member, a portion corresponding to the center portion between the radial bearing portions where substantially maximum dynamic pressure is generated. A hole is provided at a position, the both holes of the sleeve are configured as a second communication hole that communicates with each other through the inside of the sleeve, and the first communication is performed by rotationally driving the rotor. The hole is used as a fluid lubricant return path in which the fluid lubricant flows from the radial bearing portion to the thrust bearing portion, while the second communication hole is formed by the fluid lubricant from the thrust bearing portion to the radial bearing. An electric motor characterized in that it is a return path for a fluid lubricant that circulates to the section. 3. The first communication hole and / or the second communication hole.
In the middle of the communication hole of or in the opening hole, a filter member for filtering foreign matters and impurities in the fluid lubricant is mounted,
The electric motor according to claim 1 or 2.