JP2000341907A - Cooling fan motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately suppress a moving amount in an axial direction of a rotor to a fixed amount or less with a simple structure, by providing a lock member opposed by interposing a base and the rotor with a prescribed space apart in a rotor and motor axial direction, and connecting the lock member to the base. SOLUTION: A bottomed cylindrical sleeve 4 is fixed coaxially into a cylindrical part 1a of a base 1, a dynamic pressure generating groove is provided in an internal diametric surface of this sleeve 4 to constitute a bearing surface of a dynamic pressure radial bearing, and a bottom surface of the sleeve 4 is formed in spherical shape to constitute a bearing surface of a thrust bearing. Here, a lock member 10 having a thin plate shape is provided to oppose the base 1 by interposing a rotor 6, a main unit 10a of the lock member 10 is opposed by providing a prescribed space H to a mounting member 8 of the rotor 6, and tip ends of legs 10b extended to four directions are integrally connected to a frame unit 10c abutting to an end face of a wall unit 2. In this way, breaking of a seal in a bearing clearance is prevented against a shock of dropping down or the like, and rotational performance of the bearing is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling fan motor used for cooling a heat generating portion such as an MPU in an information device and a heat generating portion in an electric device.

[0002]

2. Description of the Related Art Conventionally, as a fan motor used in office machines, personal computers and the like, a motor using a dynamic pressure bearing is disclosed, for example, in Japanese Utility Model Application No. Hei 1-282786. . This fan motor is
As shown in FIG. 6, a shaft member 52 is rotatably inserted into a cylindrical sleeve 51 integrated with the base 50, and a groove for generating dynamic pressure is provided on the outer peripheral surface of the shaft member 52. A dynamic pressure radial bearing is constituted by 52 and the sleeve 51. In addition, a thrust bearing is formed by the upper surface of the receiving member 53 attached to the hole opening in the base 50 and the lower end of the shaft member 52.

The bearing gap between the shaft member 52 and the sleeve 51 is filled with lubricating oil. The stator 54 is mounted on the sleeve 51 side (base 50), and the rotor 55 is supported on the upper end of the shaft member 52 on the rotating side. The rotor 55 includes a magnet 55b disposed on the radially outer side of the stator 54, and a cap-shaped mounting member 55a for connecting the magnet 55b to the shaft member 52. A plurality of blades 56 are mounted on the radially outer peripheral surface of the rotor mounting member 55a along the circumferential direction.

Thus, the blades 56 and the rotor 44 are radially supported by the shaft member 52 (base 50) via the dynamic pressure radial bearing, and the blades 56 and the rotor 55 rotate around the stator 54. Become free,
The rotor 55 is rotated by a rotating magnetic field generated by the stator 54 to rotate the blades 56 to generate an air flow.

Here, in a cooling fan motor in which the rotation of the shaft member 52 is supported by a dynamic pressure bearing, unless means for preventing the rotor 55 from moving in the axial direction (retaining stopper) is provided, dropping during transportation is not possible. The rotor 55
The (shaft member 52) moves largely in the axial direction, and the lubricating oil in the bearing is scattered, or air enters the dynamic pressure bearing, and the performance as a dynamic pressure bearing, that is, the motor rotation performance is significantly reduced.

In the following description, the amount of movement in the axial direction may be simply referred to as the amount of movement. In the fan motor described above, an outward flange 57 is provided above the sleeve 51 (at a position higher than the magnet 55b) to prevent the rotor 55 (the shaft member 52) from coming off.
A plurality of claw-like projections 58 made of synthetic resin projecting radially outward with respect to the outer peripheral surface are fixed along the circumferential direction. And
The protrusion 58 has a thinner shape toward the tip so that the upper surface forms a taper, and the outer diameter of the protrusion 58 is elastically deformed by the contact of the magnet 55b when the mounting member is assembled. The dimension is set so as to allow the magnet 55b to pass in the axial direction and to limit the magnet 55b from passing in the axial direction after assembly.

[0007]

However, the above-mentioned conventional cooling fan motor has the following problems. In other words, it is troublesome to attach a plurality of claw-like projections 58 made of synthetic resin to the outer peripheral surface of the flange portion 57 on the upper part of the sleeve 51 as a stopper, because it takes a lot of man-hours. Further, even if a problem is found after assembling the motor, it is difficult to disassemble the motor.

In a dynamic pressure bearing in which one end of a sleeve 51 which receives a thrust force on the shaft end face is sealed, if the amount of movement is less than a certain amount even if the shaft member 52 (rotor 55) moves in the direction in which it comes off. For example, the outer peripheral surface of the shaft member 52 and the sleeve 5
Since the lubricating fluid filled in the gap between the inner diameter surfaces of the first piece acts as a pressure-resistant seal, no air enters the bearing. Therefore, when the force in the direction in which the shaft member 52 is pulled out disappears, the shaft member 52 returns to the original position.

However, even if the shaft member 52 (rotor 55) moves in the axial direction (the direction in which the shaft member 52 moves) by a certain amount or more even if the above-mentioned stopper is provided, the pressure resistance of the lubricating fluid is reduced to the internal negative pressure. As a result, air enters into the dynamic pressure bearing and loses its performance as a dynamic pressure bearing. Therefore, as a function of preventing the shaft member 52 from coming off, it is required to prevent the shaft member 52 from coming off and to suppress the amount of movement in the axial direction to a certain value or less. However, in the above-described conventional retaining structure of the cooling fan motor, it is difficult to obtain the precision of the retaining position and the position of the magnet 55b, and thus it is difficult to reliably suppress the amount of movement of the shaft member 52 to a certain value or less. Was.

In the conventional dynamic pressure bearing portion of the fan motor, the number of parts on the sleeve 51 side constituting the bearing is two.
(The sleeve 51 and the receiving member 53). Therefore, the number of assembling steps is large and the structure is complicated. Further, there is a problem that cost reduction cannot be achieved because a high assembling accuracy is required for a perpendicularity and the like when assembling the radial bearing and the thrust receiving member.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a simple structure and a cooling fan motor capable of accurately suppressing the axial movement amount of a rotor to a certain amount or less. The challenge is to provide

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a dynamic pressure radial bearing and a thrust bearing in which a shaft member is rotatably inserted into a bottomed cylindrical sleeve. The rotor and the rotor are fixed to the rotating side of the sleeve and the shaft member in a state where the non-rotating side of the sleeve and the shaft member is fixed to the base, and the blades and the magnet of the rotor are arranged radially outward of the sleeve. And a cooling fan motor supporting the blades, wherein a retaining member facing the base with the rotor interposed therebetween and facing the rotor at a predetermined gap in the motor axial direction is provided, and the retaining member is connected to the base. It is intended to provide a cooling fan motor characterized by doing the above.

[0013] Here, the connection of the retaining member to the base is as follows.
Usually, since a wall or a fan rises from the outer periphery of the base, the wall or the fan may be connected to the base via the wall or the fin. However, the retaining member may be directly connected to the base itself.
According to the present invention, when the rotor moves by a predetermined amount of movement in the direction away from the base, the rotor comes into contact with the retaining member and further movement is restricted.

Although the gap between the retaining member and the rotor becomes the maximum value of the axial movement amount of the rotor as it is, the retaining member of the present embodiment is opposed to the rotor so as to cover the rotor from the axial direction. The maximum value of the axial movement amount of the rotor can be accurately suppressed to a certain amount or less. Further, after the rotor is assembled, the retaining member may be attached so as to cover the rotor, so that the assembly and disassembly are easy.

Here, it is preferable that the retaining member is disposed so as to come into contact with the rotor at a rotational center position and as close to the rotational center position as possible when viewed from the motor axial direction. The retaining member may also serve as a heat sink. In addition, the bottomed sleeve having a substantially cylindrical shape is a radial-thrust integrated body in which a dynamic pressure radial bearing portion having a groove for generating dynamic pressure on the inner surface of the cylindrical portion and a thrust bearing portion provided on the bottom surface of the cylindrical portion connected thereto are provided. A resin dynamic pressure bearing,
It is preferable to use fluorine oil as a lubricant.

In this case, a radial thrust bearing in which a sleeve is provided with a dynamic pressure radial bearing portion having a groove for generating dynamic pressure on the inner surface of the cylindrical portion by injection molding, and a thrust bearing portion provided on the bottom surface of the cylindrical portion connected thereto. It becomes an integrated resin dynamic pressure bearing part, and the sleeve side of the bearing is easily processed, the number of parts is small, and the assembly is easy, so that the cost can be reduced.

Furthermore, if the sleeve is of a resin-integrated type,
The shaft member made of metal and the sleeve made of resin come into contact with each other due to vibration and impact, and both the shaft member and the sleeve are less likely to be damaged. In addition, by using a fluorine oil having good temperature characteristics as a lubricant, torque fluctuation with respect to a temperature change can be reduced. Moreover, the amount of evaporation of fluoro oil is small.

It is preferable that the maximum amount of movement of the rotor regulated by the retaining member is set to 20% or less of the distance (sleeve depth) from the opening end of the sleeve to the bottom surface of the inner diameter of the sleeve. However, the retaining member must not come into contact with the rotor in the normal state, and considering the ease of assembly, the maximum amount of movement of the rotor regulated by the retaining member is determined by the distance from the sleeve opening end to the sleeve inner diameter bottom surface. (Sleeve depth) is preferably set to 0.5% or more.

[0019]

Next, embodiments of the present invention will be described with reference to the drawings. 1A and 1B are diagrams showing a cooling fan motor according to the present embodiment, wherein FIG. 1A is a plan view thereof, and FIG. 1B is a sectional view thereof. First, the configuration will be described. At the center of the base 1, a cylindrical portion 1a that stands up in the axial direction is provided, and the wall 2 stands up from the outer periphery of the base 1. This base 1
The wall 2 forms a motor case. The base 1 has a plurality of outlets 1b arranged in a circumferential direction.
Is open.

A stator 3 is mounted on the outer periphery of the cylindrical portion 1a at the center of the base 1. A cylindrical sleeve 4 having a bottom is coaxially fixed in the cylindrical portion 1a. The sleeve 4 is integrally formed of a resin material in which PPS (polyphenylene sulfide resin) is filled with two or more kinds of fillers. Grooves for generating dynamic pressure are provided on the inner diameter surface of the sleeve 4 to form the bearing surface of the dynamic pressure radial bearing, and the bottom surface of the sleeve 4 is spherical to form the bearing surface of the thrust bearing.

A shaft member 5 is inserted into the sleeve 4 so as to be freely inserted and removed. The outer peripheral surface of the shaft member 5 and the inner diameter surface of the sleeve 4 constitute a dynamic pressure radial bearing,
A thrust bearing is constituted by one end surface of the shaft member 5 and the bottom surface of the sleeve 4. The bearing gap is filled with fluorine oil as a lubricant. At the other end of the shaft member 5,
The rotor 6 and the blade 7 are supported. The rotor 6 includes a mounting member 8 and a magnet 9. Mounting member 8
Is a cap-shaped member having a U-shaped cross section, the central portion of which is fixed to the other end of the shaft member 5 and extends radially outward, and the cylindrical outer peripheral portion 8a is It is arranged so that it may oppose in the direction.

A cylindrical outer peripheral portion 8a of the mounting member 8
When the magnet 9 is fixed to the inner surface, the magnet 9 faces the stator 3 in the radial direction. A plurality of blades 7 are fixed to the outer surface of the outer peripheral portion 8a along the circumferential direction. Further, a thin plate-shaped stopper member 10 is provided so as to face the base 1 with the rotor 6 interposed therebetween.

The main body 10a of the retaining member 10 is shown in FIG.
As shown in (a), it faces the center of the mounting member 8 in the axial direction with a predetermined gap H therebetween, and is coaxial or substantially coaxial with the shaft member 5. The retaining member body 10a
The legs 10b extend in four directions, and the tip of the legs 10b is integrally connected to the frame 10c that comes into contact with the end surface of the wall 2, thereby forming the retaining member 10. The fixing of the frame 10c to the wall 2 may be performed by using an appropriate fixing means such as bonding, press-fitting, caulking, or screwing. Adhesion is less preferred when considering later disassembly.

The retaining member 10 of the present embodiment serves as a lid of the case, that is, a part of the case, together with the retaining of the rotor 6 and the shaft member 5. Further, even if the retaining member 10 also serving as the lid of the case is provided, the opening except for the central portion (the retaining member main body 10a) is largely opened, so that the suction of the air is not hindered. Next, the operation and operation of the above configuration will be described.

The rotor 6 is rotatably supported around the stator 3 via a dynamic pressure bearing, is rotated by a rotating magnetic field generated by the stator 3, and is rotated in the direction indicated by an arrow X by a blade 7 provided on its outer periphery. Blow. During this rotation, a pressure is generated in the fluorine oil by the groove for generating dynamic pressure provided on the inner surface of the sleeve 4 to be supported in the radial direction, and the inner surface of the sleeve 4 and the shaft member 5 rotate without contact. In addition,
During start and stop, the inner diameter surface of the sleeve 4 and the shaft member 5 come into contact with each other. The thrust load acting on the shaft member 5 is received by point contact between the end surface of the shaft member 5 and the spherical thrust bearing surface.

Even if the rotor 6 (shaft member 5) moves in a direction in which the rotor 6 (shaft member 5) comes off the sleeve 4 due to vibration or impact during transportation of the motor or impact when dropped, the mounting member 8 constituting a part of the rotor 6 The outer surface of the rotor 6 comes in contact with the inner surface of the main body 10a of the thin plate-shaped retaining member 10 also serving as a lid of the case.
Is prevented from falling off, and the amount of movement is also H or less.
It should be noted that the rotor 6 that has moved in the pull-out direction as much as possible
The main body 10a may be made to protrude toward the rotor 6 relatively to the foot 10b so that the main body 10a comes into contact only with the foot 10b.

Further, even when the buoyancy acting on the blades 7 becomes larger than the gravity while the motor is being driven, that is, while the rotor 6 and the blades 7 are rotating, the rotor 6 (the shaft member 5) moves in the pull-out direction. The detachment prevention member body 10a prevents the detachment. However, since the detachment prevention member body 10a comes into contact with the mounting member 8 of the rotor 6 at or near the center of rotation, the swinging of the shaft member 5 and the like at the time of the contact. Can be kept small.

The retaining member 10 is also assembled with the sleeve 6 fixed to the base 1 with respect to the rotor 6 and the blade 7.
After assembling the shaft member 5 which supports the case, it can be simply attached to the wall 2 constituting the case. Also, if a problem is discovered after assembling the motor,
Since the retaining member 10 can be easily removed, disassembly (removal and insertion of the rotor 6) is also easy.

Further, since the axial movement amount (H) of the rotor 6 can be set with high accuracy, it is possible to prevent air from entering the bearing even if the rotor 6 moves in the removal direction. If the amount of movement (H) of the rotor 6 (shaft) in the axial direction is set to 20% or less of the distance L from the open end of the sleeve 4 to the inner end surface (thrust bearing surface), the rotor 6 may fall or receive some impact. However, the seal in the bearing gap is not broken and no air enters the bearing. That is, even if the rotor 6 may move in the pull-out direction, deterioration of the rotational performance of the bearing is prevented.

However, in consideration of assemblability, the rotor 6 (shaft)
Is preferably 0.5% or more of the distance L from the opening end of the sleeve 4 to the inner diameter end surface (thrust bearing surface). Further, if the axial movement amount (H) of the rotor 6 (the shaft member 5) is set to 10% or less of the distance from the opening end of the sleeve 4 to the bottom surface of the inner diameter (thrust bearing surface), the thickness of the fan motor is further reduced, which is more preferable. .

The sleeve 4 constituting one of the bearing portions
Is processed by injection molding to form a radial and thrust integral body, in which a dynamic pressure radial bearing part having a groove for dynamic pressure generation on the inner diameter surface of the cylindrical part and a thrust bearing surface on the bottom connected to it are integrally formed. A resin-made dynamic pressure bearing may be used. In this case, the grooves for generating the dynamic pressure can be provided at the same time as the injection molding, so that the processing is easy, the number of parts is small, and the assembly is easy, so that the cost can be reduced. Further, both the shaft member 5 and the sleeve 4 are less likely to be damaged by dropping, impact, and vibration.

The bottomed sleeve 4 does not necessarily need to have the cylindrical portion and the bottom formed integrally. The bottomed sleeve 4 may be formed integrally with the base 1. In addition, by using a resin material in which PPS is filled with a filler as the resin material of the sleeve 4, the sleeve 4 has excellent dimensional stability, lower friction and excellent wear resistance, and thus has excellent durability.

Here, the resin material used for the resin sleeve 4 integrated with the radial and thrust is not limited to PPS (polyphenylene sulfide resin). And a resin that can maintain rigidity even at high temperatures is preferred. Examples of such a resin include polybutylene sulfide resin, polybutylene terephthalate resin, and polyethylene terephthalate resin.

In order to further improve the performance as a dynamic pressure bearing, it is preferable to mix a powdery or fibrous reinforcing material with the above resin. By doing so, the molding accuracy is improved, and the linear expansion coefficient is suppressed to a small value.
Changes in the radial gap due to temperature are reduced. Glass powder, glass peas, silica, calcium carbonate, and glass fiber and carbon fiber can be exemplified as the powdery reinforcing material to be mixed with the resin, and the fibrous reinforcing material.

Further, in the dynamic pressure bearing, the shaft member 5 and the sleeve 4 come into contact with each other at the initial rotation of the rotor 6 and each time the rotor 6 stops. Furthermore, in the thrust bearing, since the end face of the shaft member 5 and the bottom face of the sleeve 4 are always in contact even during rotation, wear resistance is also required. Therefore, the resin has abrasion resistance,
It is more preferable to incorporate a filler that improves slidability. Examples of the filler include polytetrafluoroethylene resin powder and carbonized phenol particles. These may be used alone or in combination of two or more.

Further, by using a fluorine oil having good temperature viscosity characteristics as a lubricating oil, torque increase at a low temperature is small and load capacity at a high temperature is hardly reduced. Here, even if the fluorine oil has poor lubricating properties, it is excellent in durability because it is a resin integrated with low friction and excellent wear resistance. Furthermore, since the amount of evaporation is small, oil is secured for a long time, and thus the durability is excellent.

Here, as described above, if the axial movement amount (H) of the rotor 6 (shaft) is set to 20% or less of the distance L from the open end of the sleeve 4 to the inner end surface (thrust bearing surface), Since the seal in the bearing gap is not broken by the movement of the shaft member 5 and the problem that the rotation performance of the bearing is reduced due to the incorporation of air can be avoided, mineral oil, silicon oil, and other various oils can be used instead of the fluorine oil. There is no problem even if the lubricating oil is applied.

Further, the outer shape of the motor is not limited to the embodiment, and the motor may be irregularly shaped or provided with a flange or the like. Further, the materials of the base 1 and the wall 2 constituting the case are not limited to metals, but may be resins. Further, the groove for dynamic pressure generation is not limited to the pattern shown in the figure, but may be any groove pattern and groove width ratio functioning as a dynamic pressure bearing, and the groove for dynamic pressure generation may be provided on the shaft member 5 side. May be provided.

The structure of the retaining member 10 is not limited to the above-described shape. The point is that it is only necessary to face the rotor 6 at a predetermined interval in the axial direction. For example, it may be composed of a wire mesh member. Further, the basic configuration of the cooling fan motor is not limited to the configuration described above, and another known motor configuration may be adopted.

As is clear from the above, the retaining member 1
Even if 0 is provided, the motor structure is simple, assembly is easy, and the cost is low. In addition, since the amount of axial movement of the rotor 6 can be accurately suppressed to a certain value or less, air can be prevented from entering the inside of the dynamic pressure bearing, so that the cooling fan motor has high performance and excellent durability. Next, a second embodiment will be described with reference to the drawings. In addition, about the member similar to the said embodiment, the same code | symbol is attached | subjected and the detail is abbreviate | omitted.

FIG. 2 is a sectional view of the cooling fan motor according to this embodiment. The basic configuration of this embodiment is the same as that of the first embodiment.
This is the same as the embodiment, except that the base 1 constitutes a heat sink made of a conductive metal having good thermal conductivity, and the outer periphery of the blade 7 is provided with metal fins 20 instead of the wall 2. is there. With this configuration, a thinned fan motor suitable as a cooling fan motor for directly cooling an MPU (microprocessor unit) is provided.

The frame 10c of the retaining member 10 is attached to the upper end of the fin 20. In this case, by making the retaining member 10 made of metal,
The retaining member 10 can also serve as a part of the heat sink. Other configurations, operations and effects are the same as those of the first embodiment. Next, a third embodiment will be described with reference to the drawings. In addition, about the member similar to the said embodiment, the same code | symbol is attached | subjected and the detail is abbreviate | omitted.

FIG. 3 is a sectional view of a cooling fan motor according to this embodiment. The basic configuration of this embodiment is the same as that of the first embodiment.
Same as the embodiment, except that the cylindrical portion 1
The difference is that the sleeve 4 is directly fixed to the base 1 without providing a. Accordingly, the stator 3 (the substrate on which the coil is provided) is directly attached to the outer diameter surface of the sleeve 4.

With this configuration, there is an advantage that the processing cost is reduced because the structure of the case is simplified. Further, in the present embodiment, the rotor 6 and the stator 3 are disposed so as to face each other not in the radial direction but in the axial direction. By doing so, there is an advantage that the motor can be made more compact (thin) because the axial dimension can be reduced.

Other functions and effects are the same as those of the first embodiment. Here, in the third example, a case similar to the first embodiment including the base 1 and the wall 2 is described as an example, but the base 1 constitutes a heat sink similarly to the second embodiment. Alternatively, the wall 2 may be configured by the fins 20. In this case, there is an advantage that a more compact (thin) cooling fan motor for MPU or the like can be provided as compared with the second embodiment.

Next, a fourth embodiment will be described with reference to the drawings. In addition, about the member similar to the said embodiment, the same code | symbol is attached | subjected and the detail is abbreviate | omitted. FIG.
1 shows a cross-sectional view of a cooling fan motor according to the present embodiment. In the present embodiment, the shaft member 5 is fixed to the base 1, and the sleeve 4 rotates.

That is, inside the material of the cylindrical portion 1a protruding at the center of the base 1, the cylindrical portion 1a
A shaft member 5 protrudes coaxially with the material, and a bottomed cylindrical sleeve 4 is rotatably inserted into the shaft member 5. The rotor 6 and the blade 7 similar to the first embodiment are supported on the end of the sleeve 4. In the present embodiment, the retaining member 1
Reference numeral 0 denotes a heat sink, which faces the mounting member 8 of the rotor 6 with a predetermined gap H from below. A plurality of fins 20 are raised from the outer peripheral portion of the retaining member 10 also serving as a heat sink toward the base 1 side, and the fins 20 and the base 1 are fixed by screws or the like, whereby the retaining member 10 is fixed. Is connected to the base 1. In the present embodiment, since it is not necessary to suck in air from the retaining member 10 side, the retaining member 10 is formed of a single metal flat plate. It is preferable that the center portion is relatively protruded toward the rotor 6 so that the center portion is in contact with the rotor 6.

In the configuration of this embodiment, the retaining member 10
The device itself can also serve as a heat sink. Other configurations, operations, effects, and the like are the same as those in the above embodiment. Here, in the present embodiment, the end surface of the shaft member 5 is a spherical surface, and the thrust bearing surface formed by the bottom surface of the sleeve 4 is a flat surface. As in the other embodiments, the sleeve 4
May be a spherical surface on the bottom side. Also, in other embodiments, the end surface of the shaft member 5 may be a spherical surface, and the thrust bearing surface formed by the bottom surface of the sleeve 4 may be a flat surface. Also,
The end surface of the shaft member 5 may be spherical, and the thrust bearing surface formed by the bottom surface of the sleeve 4 may be spherical.

Also, in another embodiment, the shaft member 5
May be the non-rotating side, and the sleeve 4 side may be the rotating side.
Next, a fifth embodiment will be described with reference to the drawings. In addition, about the member similar to the said embodiment, the same code | symbol is attached | subjected and the detail is abbreviate | omitted. FIG. 5 is a cross-sectional view of the cooling fan motor according to the present embodiment.

The basic structure of this embodiment is the same as that of the first embodiment, except that a gap adjusting means is provided on the retaining member 10. That is, the retaining member main body 10a
Is provided with a through hole 23 penetrating in the thickness direction.
3 is passed through a rod 24 for adjustment by press-fitting.
Are projected to the rotor 6 side.

Thus, the maximum amount of movement of the rotor 6 (shaft member 5) in the retaining direction is restricted by the amount of protrusion of the rod 24, and by adjusting the amount of protrusion of the rod 24,
Has the advantage that the maximum axial movement can be adjusted after the motor is assembled. Even if there is a dimensional error or the like in the height of the wall 2 constituting the case, the maximum amount of axial movement of the rotor 6 can be reliably set to be equal to or less than the predetermined amount of gap by the gap adjusting means. Further, by providing the gap adjusting means in the central portion, only one place for installing the gap adjusting means is required.

Other structures, operations and effects are the same as those of the above embodiment. In addition, the said gap adjustment means is not limited to the said structure. For example, the through hole 23 is a screw hole,
The rod 24 may be constituted by a screw. In addition, the gap adjusting means can be provided in other embodiments.

[0053]

EXAMPLE Using the cooling fan motor of the first embodiment, a test was performed on the gap H between the retaining member 10 and the rotor 6, that is, the maximum amount of movement of the rotor 6 (the shaft member 5) in the removing direction. went. Constructing a cooling fan motor by combining the following various dimensions with respect to the shaft member 5, the depth of the bottomed resin sleeve 4, and the bearing radial gap (ΔR), which are parts constituting the dynamic pressure bearing portion of the motor. The test was carried out. The viscosity of the lubricating oil used was 15 cSt / 40
° C, and the number of impacts of bringing the rotor 6 into contact with the retaining member 10 was set to 20 times.

Shaft diameter of shaft member 5: φ3 mm and φ5 mm Depth: 5 mm, 10 mm, and 15 mm as bottomed resin sleeve 4 Bearing radius gap (ΔR): 5 μm, 10 μm, 15 μm
As a result of the 20 μm test, no differences due to differences in the shaft diameter of the shaft member 5 and the depth of the bottomed sleeve 4 were found.
(The maximum amount of axial movement / depth of the bottomed sleeve 4) and the bearing radial clearance are summarized. Table 1 shows the test results.

[0055]

[Table 1]

Here, the bearing radial gap ΔR was tested up to 20 μm in consideration of the range in which performance could be used. In addition, the evaluation of the test was based on the presence or absence of performance deterioration during rotation due to the inflow of air into the sleeve 4.
In other words, when the lubricating oil in the bearing gap breaks and air enters, the force of the oil film to support the rotational force of the bearing becomes insufficient, so that a whirling corresponding to a half frequency of the so-called rotation speed is generated, and the vibration is reduced. As a result, the rotation performance of the bearing cannot be satisfied.

In Table 1, the mark x indicates the case where the pressure-resistant sealing effect of the bearing gap was broken and the whirling occurred due to the axial movement of the rotor 6 (shaft member 5). This is the case where the shaft member 5 has risen to the maximum amount regulated by the member 10, but no whirl occurs when the shaft member 5 is returned to its original position and rotated thereafter. As can be seen from Table 1, the smaller the amount of axial movement is, the better. By setting (maximum amount of axial movement / depth of bottomed sleeve 4) to 20% or less, generation of whirl is reliably prevented. It can be seen that deterioration of the rotation performance of the motor can be prevented even if there is movement in the axial direction.

[0058]

As described above, when the present invention is employed, the retaining member is attached so as to cover the rotor, and the gap between the retaining member and the rotor is left as it is.
Since the maximum value of the axial movement amount of the rotor is obtained, there is an effect that the maximum value of the axial movement amount of the rotor can be accurately suppressed to a certain amount or less.

Further, since the retaining member constitutes the outer peripheral portion of the motor, it can also serve as a part of the case or a heat sink. Also, after assembling the rotor,
Since the retaining members may be individually attached so as to cover the rotor, assembly and disassembly are easy.

[Brief description of the drawings]

1A and 1B are views showing a cooling fan motor according to a first embodiment of the present invention, wherein FIG. 1A is a plan view thereof, and FIG.
Is a sectional view thereof.

FIG. 2 is a sectional view showing a cooling fan motor according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a cooling fan motor according to a third embodiment of the present invention.

FIG. 4 is a sectional view showing a cooling fan motor according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view showing a cooling fan motor according to a fifth embodiment according to the present invention.

FIG. 6 is a cross-sectional view showing a conventional cooling fan motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base part 2 Wall body 3 Stator 4 Sleeve 5 Shaft member 6 Rotor 7 Blade 8 Mounting member 9 Magnet 10 Retaining member 10a Retaining member main body 10b Foot 10c Frame 20 Fin 23 Through-hole (gap adjusting means) 24 Rod ( Gap adjusting means)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 5/167 H02K 5/167 B 7/14 7/14 A F term (Reference) 3H034 AA02 BB02 BB08 BB20 CC03 DD28 EE03 EE05 EE09 3J011 AA04 AA09 BA02 BA10 CA02 QA11 SC01 5H605 AA07 AA08 BB05 BB14 BB19 BB20 CC04 EB02 EB06 5H607 BB13 BB14 BB17 BB25 CC01 DD03 FF04 GG01 GG02 GG12 GG15

Claims (1)

[Claims] 1. A shaft member is rotatably inserted into a bottomed cylindrical sleeve to form a dynamic pressure radial bearing and a thrust bearing by the sleeve and the shaft member, and a non-rotating side of the sleeve and the shaft member is formed. A cooling fan motor fixed to the base and having the blades and the rotor magnets disposed radially outward of the sleeve and having the rotor and the blades supported on the rotating side of the sleeve and the shaft member; A cooling fan motor, comprising: a retaining member that faces the rotor and that faces the rotor with a predetermined gap in the motor axis direction, and the retaining member is connected to the base.