JP3709081B2 - Small motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a small motor for rotational driving such as a CD-ROM and a DVD-ROM and other various uses, and more particularly to a structure for preventing the rotor from coming off in the axial direction.
[0002]
[Prior art]
In small motors for various applications, removal prevention means is taken so that a rotor portion composed of a rotor case, a rotating shaft, a rotor magnet, and the like does not come off from the bearing. FIG. 3 shows an example of a structure for preventing the rotor from coming off, which is generally used conventionally. In FIG. 3, a cylindrical bearing 51 is fitted and fixed on the inner peripheral side of a cylindrical bearing holder 50 by press fitting or the like. The bearing 51 is made of sintered metal, and a rotation shaft 52 is inserted into the center hole thereof. The rotation shaft 52 is supported to be rotatable in the radial direction. A circumferential groove is formed at the lower end portion of the rotating shaft 52, and a washer 53 is fitted into the circumferential groove. When the rotating shaft 52 is about to be pulled upward from the bearing 51, the washer 53 comes into contact with the lower end of the bearing 51. So that it can be secured. After the washer 53 is fitted to the rotary shaft 52, a thrust receiver 54 is fitted and fixed to the inner periphery of the lower end of the bearing holder 50 so that the thrust receiver 54 receives a load downward in the thrust direction of the rotary shaft 52. ing.
[0003]
Although not shown in FIG. 3, the outer periphery of the bearing holder 50 is fitted into the hole of the substrate and is fixed to the substrate, and the stator core is fixed to the outer periphery of the bearing holder 50. The upper end portion of the rotating shaft 52 protrudes upward from the upper end surface of the bearing 51, and a rotor including a rotor case, a rotor magnet, and the like is fixed thereto.
[0004]
In addition to the general rotor slip prevention structure described above for small motors, a rotor slip prevention structure as described in Japanese Patent Application Laid-Open No. 10-201164 according to the applicant's application is also known. Yes. This is because the removal prevention ring is temporarily attached to the bottom plate of the bearing holder, and the removal prevention ring temporarily secured to the provisional attachment portion is inserted through the through hole of the bottom plate to insert the operation member. Are forcibly pushed and moved so that the slip-off prevention ring is transferred from the temporary fixing portion to the circumferential groove of the rotating shaft to prevent the rotor including the rotating shaft from being removed from the bearing. The drop prevention ring has an elastic urging force in the direction of diameter reduction, and is attached to the circumferential groove of the rotating shaft. According to the invention described in the above publication, the rotor can be prevented from being detached from the outside after the rotating shaft is inserted into the bearing held by the bearing holder.
[0005]
[Problems to be solved by the invention]
According to the structure for preventing the rotor from slipping in the conventional small motor as shown in FIG. 3, it is necessary to form a circumferential groove for fitting the washer at one end of the rotating shaft, and the washer and the washer are used as the rotating shaft. After the fitting, a thrust receiver that is fixed to the inner periphery of the lower end of the bearing holder is required, and there is a problem in that the cost of the parts increases due to the complexity of parts machining and the increase in the number of parts. Further, both the conventional small motor shown in FIG. 3 and the small motor described in the above publication are provided with a circumferential groove at one end portion of the rotating shaft and a washer or ring for preventing it from being removed. Cannot be supported by the radial bearing, and when the required bearing length is secured, the length of the rotating shaft becomes long, which becomes an obstacle to the reduction in thickness of the motor. This will be described with reference to the example of FIG. 3. As a space for providing a washer 53 for preventing slippage between the lower end surface of the radial bearing 51 and the upper surface of the thrust receiver 54, that is, the thrust load receiving surface of the rotating shaft 52, It is necessary to ensure the axial length A, and the range of the length A cannot be supported by the radial bearing 51. Therefore, if the length of the radial bearing 51 necessary to support the rotating shaft 52 is secured, It is necessary to increase the length of the rotating shaft 52 by the length A, which becomes an obstacle to the reduction in thickness of the motor.
[0006]
Furthermore, according to the conventional small motor described above, when it is attempted to disassemble due to replacement of defective parts or inaccuracy after assembly, the thrust receiver or bottom plate is removed from the bearing holder, and then removed from the rotating shaft. It is necessary to remove the locking washer and ring, which is cumbersome to disassemble and forcibly removes the thrust receiver or bottom plate from the bearing holder.Therefore, it is easy to damage the parts, and in many cases the damaged parts must be discarded. It was.
[0007]
The present invention has been made to solve the above-described problems of the prior art. It is easy to assemble, has a small number of parts, and can effectively use the length range of the rotating shaft as a radial bearing portion. It is an object of the present invention to provide a small motor that facilitates thinning of the motor, can be easily disassembled if necessary, and does not damage parts during disassembly.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 of the present application includes a cylindrical bearing holder, a radial bearing held in the bearing holder, a rotating shaft rotatably supported by the radial bearing, and fixed to one end of the rotating shaft. In a small motor comprising a rotor including a rotor case, a rotor magnet integrally attached to the rotor case, and a stator core fixed to the outer peripheral surface of the bearing holder so as to face the rotor magnet, the rotor motor is formed in a C shape. And a stopper formed with a hook portion. The stopper is attached to the outer peripheral portion of the bearing holder with the C-shaped inner peripheral side, and the hook portion faces a part of the rotor so that the shaft of the rotor The rotor has a through hole at a position corresponding to the hook portion of the stopper. And said that you are.
[0009]
As in the second aspect of the present invention, the inner peripheral edge of the stopper may be brought into contact with the engaging portion formed at the end of the bearing holder.
As in the third aspect of the present invention, a hook portion is provided on the outer peripheral side of the stopper, and a locking portion for locking the rotor case is provided at the tip of the hook portion when the rotor is about to come off in the axial direction. Good.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a small motor according to the present invention will be described with reference to FIGS. 1 and 2.
In FIG. 1, a hole 1 into which a bearing holder 3 is press-fitted is formed in a substrate 1 made of a metal plate such as iron, and the periphery of this hole is a burring portion 2 that is drawn into a cylindrical shape on the upper side. . The bearing holder 3 is press-fitted into the burring portion 2, and a stopper 25 is fitted in advance on the outer periphery of the bearing holder 3, and the stator core 5 is press-fitted from below. The bearing holder 3 is formed into a bottomed cylindrical shape by drawing a metal plate, and the outer periphery of the lower end thereof is press-fitted into the burring portion 2 of the substrate 1 and fixed. A small flange-like engaging portion 4 is formed on the outer peripheral side of the upper end portion of the bearing holder 3, and the stopper 25 is prevented from coming off by the engaging portion 4. The center hole of the stator core 5 is fixed by being press-fitted into the outer periphery of the bearing holder 3. The stopper 25 will be described in detail later. The stator core 5 is a laminated core composed of a plurality of core plates, and has a plurality of salient poles radially, and a drive coil 6 is wound around each salient pole.
[0011]
A thrust receiving plate 9 is disposed on the inner bottom of the bearing holder 3, and a radial bearing 7 is fitted on the inner periphery of the bearing holder 3, and the radial bearing 7 is held by the bearing holder 3. In this embodiment, the radial bearing 7 is a sintered oil-impregnated bearing, and the axial length of the radial bearing 7 is slightly shorter than the axial dimension on the inner peripheral side of the bearing holder 3. A rotary shaft 8 is inserted on the inner peripheral side of the radial bearing 7, and the rotary shaft 8 is supported by the radial bearing 7 so as to be rotatable around its central axis. The lower end of the rotating shaft 8 is in contact with the thrust receiving plate 9 so that the thrust load applied to the rotating shaft 8 is supported by the thrust receiving plate 9. The radial bearing 7 is impregnated with lubricating oil, and the space between the inner peripheral surface of the radial bearing 7 and the outer peripheral surface of the rotary shaft 8 is lubricated with the lubricating oil. Since the bearing holder 3 is formed in a bottomed cylindrical shape and has a bag shape, the bearing holder 3 has a structure capable of preventing the lubricating oil from flowing out of the bearing holder 3.
[0012]
The upper end portion of the rotary shaft 8 extends upward from the upper end portions of the radial bearing 7 and the bearing holder 3, and the auxiliary ring 17 is press-fitted into the upper end portion of the rotary shaft 8 and the hub base 11 is press-fitted from above. Has been. The auxiliary ring 17 is made of a metal plate and has a cylindrical downward burring portion around the center hole. The burring portion is press-fitted into the rotary shaft 8. The hub base 11 is also made of a metal plate press-molded product, and has a cylindrical upward burring portion 12 around the center hole. The burring portion 12 is press-fitted into the rotary shaft 8. The hub base 11 is raised so that a ring-shaped groove 13 whose upper side is open is formed on the outer side of the burring part 12, and further, a conical part 34 that gradually falls toward the outer side. A cylindrical portion 35 and a horizontal portion 36 following the cylindrical portion 35 are formed. A pad 16 is attached to the upper surface of the horizontal portion 36. As is apparent from the configuration of the hub base 11, the small motor shown in the figure is a motor for driving the disk, and the center hole of the disk is positioned on the outer peripheral side of the cylindrical portion 35 and is positioned on the pad 16. A disc is to be placed. A ring-shaped magnet 14 that functions as a chucking magnet is inserted and fixed in the groove 13. When a disk presser (not shown) descends with the disk placed on the pad 16, the disk presser is attracted to the hub base 11 side by the magnetic attractive force between the magnetic body of the disk presser and the magnet 14. The disk is pressed toward the hub base 11. The disk presser is rotatably provided together with the hub base 11, the rotor 10 of the motor including the rotating shaft 8, and the disk.
[0013]
An upper end surface of a rotor case 20 that forms a part of the rotor 10 is integrally fixed to the lower surface side of the hub base 11 by welding or other appropriate means. The rotor case 20 is shaped like an upside down cup, and a portion corresponding to the bottom of the cup is overlapped and fixed on the lower surface of the hub base 11. A cylindrical rotor magnet 21 is attached to the inner surface of the cylindrical peripheral wall of the rotor case 20. The rotor magnet 21 is also a part of the rotor 10 and can rotate together with the rotor case 20. The inner peripheral surface of the rotor magnet 21 faces the outer peripheral surface of the stator core 5 with an appropriate gap. By switching and controlling the energization of the drive coils of each phase according to the rotational position of each magnetic pole of the rotor magnet 21, the rotor 10 and the disk are continuously connected by the magnetic attractive repulsive force between the rotor magnet 21 and each salient pole. Are driven to rotate.
[0014]
In the embodiment shown in FIG. 1, the rotating shaft 8 has a simple columnar shape, and is not formed with a peripheral groove for fitting a washer or a ring for retaining it as in the above-described conventional example. Instead, means for preventing the rotor from coming off using the stopper 25 is provided. As shown in FIG. 2B, the stopper 25 has a C-shaped flat shape, that is, a shape viewed from the axial direction of the motor. The spread angle (center angle) of the C-shaped stopper 25 is slightly larger than 180 °, and is about 240 ° in the illustrated example. The stopper 25 is an integrally molded product of an elastic material such as resin, and can be expanded and contracted by applying external force. As shown in FIGS. 2A, 2 </ b> B, and 2 </ b> C, the stopper 25 is attached to the outer peripheral portion of the bearing holder 3 on the inner peripheral side of the planar C-shape. The inner peripheral edge of the stopper 25 rises to form a jetty 28, and the upper end of the jetty 28 abuts on the engaging portion 4 of the bearing holder 3 as described above to prevent the stopper 25 from coming off. . A hook portion 26 is formed on the outer peripheral side of the stopper 25. The hook portion 26 has a shape in which a part of the outer periphery of the stopper 25 rises, and is formed at three locations in the circumferential direction of the stopper 25, that is, at both ends and the center portion of the C-shape. At the tip of each hook portion 26 is formed a locking portion 27 that protrudes outward in the radial direction of the motor, and the outer upper end portion of each locking portion 27 is an inclined surface 29 that decreases radially outward. Yes.
[0015]
In FIG. 1, a central hole is formed in a portion corresponding to the bottom of the cup of the cup-shaped rotor case 20 described above, and a step portion along a concentric circle is formed outside the central hole. 22 is located below the lower surface of the hub base 11 and faces the lower side of the locking portion 27 of the stopper 25 with a slight gap. Accordingly, when the rotor 10 of the motor composed of the rotor case 20 and the like tries to come out of the radial bearing 7 together with the rotating shaft 8, the edge portion 22 of the rotor case 20 is brought into contact with the locking portion 27 and locked. Omission is prevented.
The rotor 10, more specifically, the hub base 11 constituting the rotor 10, has a through hole 15 at a position corresponding to the hook portion 26 of the stopper 25. The through holes 15 may be formed at only one place, but may be formed at three places so as to be able to correspond to the hook portions 26 at the same time. A thin jig 32 can be inserted from the through-hole 15 as shown by a chain line in FIG. 1, and the locking portion 27 of the hook portion 26 can be pushed inward in the radial direction at the tip of the jig 32. It can be done.
[0016]
A circuit board 30 is placed and fixed on the upper surface of the substrate 1. An appropriate circuit pattern is formed on the circuit board 30 and an appropriate circuit component, for example, a magnetic detection element 31 including a Hall element for detecting an index or a rotation speed of the rotor 10 is mounted.
[0017]
Next, the assembly procedure of the small motor according to the above embodiment, particularly the assembly of the rotor 10 to the stator will be briefly described. A radial bearing 7 is press-fitted on the inner peripheral side of the bearing holder 3, a stopper 25 is inserted on the outer peripheral side of the bearing holder 3, and then the center hole of the stator core 5 is press-fitted and fixed. Next, the outer periphery of the lower end portion of the bearing holder 3 is lightly press-fitted into the burring portion 2 of the substrate 1. The light press-fitting is not a strong press-fitting, but means a press-fitting with a relatively weak strength that can correct the relative positional relationship and mutual posture of the members. Next, the rotary shaft 8 of the rotor 10 integrated around the rotary shaft 8 is inserted into the center hole of the radial bearing 7. At that time, the edge portion 22 of the rotor case 20 hits the inclined surface 29 of the locking portion 27 of the stopper 25, and the edge portion is bent while bending the hook portion 26 of the stopper 25 inward in the radial direction against its elastic force. 22 goes down. When the edge portion 22 reaches below the locking portion 27, the hook portion 26 is restored by its elastic force, and the locking portion 27 advances above the edge portion 22 to prevent the rotor from coming off. It becomes a structure. The contact portion of the edge portion 22 of the rotor case 20 with the engaging portion 27 is chamfered so that the edge portion 22 of the rotor case 20 can easily bend the hook portion 26 of the stopper 25 when the rotor 10 is assembled.
[0018]
The perpendicularity of the rotating shaft 8 to the surface of the substrate 1 needs to be adjusted with high accuracy. In particular, high accuracy is required for a disk drive motor. Therefore, when the assembly is completed, the perpendicularity of the rotary shaft 8 to the surface of the substrate 1 is confirmed using an appropriate jig or the like. If the accuracy is not high, the substrate 1 and the bearing holder 3 Correct the relative posture in the light press-fitting part to get the above verticality. In this state, the substrate 1 and the bearing holder 3 are finally fixed using means such as bonding or welding the light press-fitting portions.
[0019]
Even after the final assembly is completed as described above, a defective portion may be found, and it may be necessary to separate the rotor 10 from the stator and replace or adjust the defective portion. In that case, as shown in FIG. 1, the jig 32 is inserted from the through hole 15 of the hub base 11 constituting the rotor 10, and the inclined surface 29 of the locking portion 27 of the stopper 25 is radiused at the tip of the jig 32. Push inward. By doing so, the hook portion 26 is bent and the engaging portion 27 is retracted radially inward from the edge portion 22 of the rotor case 20. In this state, the rotor 10 including the rotating shaft 8 can be extracted from the stator.
[0020]
Thus, according to the above-described embodiment, the stopper 25 is interposed between the bearing holder 3 and the rotor 10, and the stopper 25 is attached to the outer peripheral portion of the bearing holder 25 and the locking portion 27 of the hook portion 26 is attached. The rotor 10 is prevented from coming off in the axial direction by facing the edge portion 22 of the rotor case 10 which is a part of the rotor 10. The rotor 10 has a through hole at a position corresponding to the hook portion 26 of the stopper 25. 15 is formed, if necessary, an appropriate jig or tool is inserted through the through-hole 15 and the locking portion 27 of the hook portion 26 is retracted from the edge portion 22 of the rotor 10 so that the rotor 10 and the stator Can be separated, and parts can be easily replaced and adjusted. In addition, when the rotor 10 and the stator are separated, an excessive force is not applied to each component. Therefore, the rotor 10 and the stator can be separated without damaging the components, and the components can be reused. Even if a specific part has a defect, the defective part of the part can be repaired and reused.
[0021]
If the rotor 10 and the stator are separated from each other, and if there is a problem that the hook portion 26 of the stopper 25 is broken or cracked, the stopper 25 is replaced. The stopper 25 has a C-shaped planar shape, a central angle that is slightly larger than 180 °, and is made of an elastic member. Therefore, the stopper 25 is made of elastic material with the rotor 10 separated from the stator. The C-shaped open part is pulled out from the bearing holder 3 while expanding 25, and the defective stopper 25 can be removed. In order to attach a new stopper 25 to the bearing holder 3, the stopper 25 may be expanded and fitted to the outer periphery of the bearing holder 3. As described above, even if a failure occurs in the parts when the rotor 10 and the stator are separated, the only part where the failure occurs is the inexpensive stopper 25, and the stopper 25 is easily attached to and detached from the bearing holder 3. There are advantages that can be made.
[0022]
Furthermore, since there is no need to provide a circumferential groove for mounting a retaining ring or the like on the rotating shaft 8 unlike a conventional small motor, the length of the rotating shaft 8 can be shortened accordingly. The motor can be thinned. If this is seen from another viewpoint, the bearing length of the rotating shaft 8 by the radial bearing 7 can be lengthened, and a smooth motor with less rotor runout can be obtained.
[0023]
In the illustrated embodiment, the motor is for driving the disk rotation, but the motor according to the present invention is not limited to this, and can be used as a general small motor.
Small motor according to the present invention, a small radial dimension, it is advantageous to small motor margin in the height direction.
[0024]
【The invention's effect】
According to the first aspect of the present invention, the stopper is interposed between the bearing holder and the rotor, the stopper is attached to the outer peripheral portion of the bearing holder, and the hook portion is opposed to a part of the rotor so that the axial direction of the rotor. Since the rotor has a through hole at a position corresponding to the hook portion of the stopper, if necessary, an appropriate jig or tool is inserted from the through hole and the hook portion is inserted into the rotor. The rotor and the stator can be separated from each other by retreating from a part of the rotor, and parts can be easily exchanged and adjusted. In addition, when the rotor and the stator are separated from each other, an excessive force is not applied to each component, so that the component can be reused without damaging the component. Even if a specific part has a defect, the defective part of the part can be repaired and reused.
[0025]
In addition, if a problem occurs such as when the stopper is damaged or cracked when the rotor and the stator are separated, the stopper may be replaced. Since the stopper is C-shaped in plan and is made of an elastic member, the C-shaped open part is pulled out from the bearing holder while expanding the stopper using elasticity, and the defective stopper is easily removed. be able to. In order to attach a new stopper to the bearing holder, it is only necessary to expand the stopper and fit it to the outer periphery of the bearing holder.
Furthermore, since there is no need to provide a circumferential groove on the rotating shaft for attaching a retaining ring or the like unlike a conventional small motor, the length of the rotating shaft can be shortened accordingly. Thinning can be achieved.
[0026]
According to the second aspect of the present invention, since the inner peripheral side edge of the stopper is in contact with the engaging portion formed at the end of the bearing holder, the stopper is disposed on the inner peripheral side of the bearing holder. It is possible to prevent the bearing holder from coming off by simply attaching it to the part, and there is no need to perform axial and circumferential positioning.
[0027]
According to the third aspect of the present invention, the hook portion is provided on the outer peripheral side of the stopper, and a locking portion for locking the rotor case when the rotor is about to come off in the axial direction is provided at the tip of the hook portion. Since it is provided, the locking portion may be retracted from a part of the rotor by an appropriate jig or tool inserted from the through hole, whereby the rotor and the stator can be separated.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of a small motor according to the present invention.
2A is a side view, FIG. 2B is a plan view, and FIG. 2C is a front sectional view showing a stopper in the embodiment.
FIG. 3 is a longitudinal sectional view showing an example of a structure for preventing a rotor from coming off in a conventional small motor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 3 Bearing holder 4 Engagement part 5 Stator core 7 Radial bearing 8 Rotating shaft 10 Rotor 15 Through-hole 20 Rotor case 21 Rotor magnet 22 Edge 25 which forms a part of rotor 25 Stopper 26 Hook part 27 Locking part

Claims (3)

A cylindrical bearing holder; a radial bearing held in the bearing holder; a rotary shaft rotatably supported by the radial bearing; a rotor including a rotor case fixed to one end of the rotary shaft; In a small motor provided with a rotor magnet integrally attached to the rotor case, and a stator core fixed to the outer peripheral surface of the bearing holder so as to face the rotor magnet,
Having a stopper formed in a C shape and a hook part;
The stopper is attached to the outer peripheral portion of the bearing holder with the C-shaped inner peripheral side, and the hook portion faces a part of the rotor to prevent the rotor from coming off in the axial direction.
A small motor, wherein a through hole is formed in the rotor at a position corresponding to the hook portion of the stopper. The small motor according to claim 1, wherein the inner peripheral edge of the stopper is in contact with an engaging portion formed at an end of the bearing holder. 2. The small-sized device according to claim 1, wherein a hook portion is provided on the outer peripheral side of the stopper, and a hook portion for locking the rotor case when the rotor is about to come off in the axial direction is provided at the tip of the hook portion. motor.

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