JP4512886B2 - Coreless motor - Google Patents

Description

  The present invention relates to a coreless motor used in a vibration alarm device or the like.

For example, a vibration alarm device that is incorporated in a mobile phone and notifies an incoming call is configured by attaching an eccentric weight to a rotating shaft of a motor. As such a motor, there is a coreless motor as disclosed in Japanese Patent Laid-Open No. 9-23628.
This coreless motor has the configuration shown in FIG. That is, the columnar field magnet 3 is fixed to the bottom of the cylindrical housing case 2, while the bearing house 70 is fixed to the opening end side of the housing case 2. A cylindrical coil 8 is attached to one end of the rotating shaft 6 rotatably supported by the bearing house 70 via a coil support 7 in the housing case 2. The cylindrical coil 8 extends in the gap between the inner wall of the housing case 2 and the field magnet 3 toward the bottom of the housing case 2. The rotating shaft 6, the coil support 7 and the cylindrical coil 8 constitute a rotor 5, and the coil support 7 is provided with a commutator 9.
The other end of the rotating shaft 6 extends outward from the bearing house 70, and an eccentric weight 30 is attached to the tip thereof. A collar 32 is provided between the eccentric weight 30 and the end face of the bearing house 70.

FIG. 7 is an enlarged sectional view showing details of the bearing house in the conventional coreless motor as described above.
The bearing house 70 includes a large-diameter portion 11 fitted into the housing case 2 and a small-diameter portion 72 extending outward from the large-diameter portion. The small-diameter portion 72 has an end surface 73 whose tip is perpendicular to the axial direction. The straight portion has a constant diameter over a predetermined distance from the vicinity of the large-diameter portion 11. At the tip of the small-diameter portion 72, the corners of the end surface 73 and the outer peripheral surface 74 in the longitudinal section of FIG.

The shaft hole 75 of the small diameter portion 72 is provided with slide bearing portions 76, 76 at both ends in the axial direction, and a section sandwiched between the slide bearing portions 76, 76 becomes an escape portion 77 having an inner diameter larger than the diameter of the rotary shaft 6. ing. The boundary between the sliding bearing portion 76 and the escape portion 77 has an R shape that is smoothly connected to the sliding bearing portion 76.
The coreless motor configured with the bearing house 70 as described above can use a columnar field magnet 3 that does not have a hole through which the rotating shaft passes, and thus can reduce the diameter of the magnet. There is an advantage that the entire size can be easily reduced, such as a rotation shaft diameter of 0.7 mm.
Japanese Patent Laid-Open No. 9-23628

Incidentally, a molding die as shown in FIG. 8 is used to manufacture such a bearing house 70.
The fixed mold 81 is provided with a resin injection gate 48 on a surface 83 corresponding to the outer peripheral surface 74 of the small diameter portion.
The movable side mold 85 defines the outer shape of the large diameter part 11, and the boundary between the large diameter part 11 and the small diameter part 72 is a parting line between the fixed side mold 81 and the movable side mold 85.
The core 86 forming the shaft hole 75 through which the rotary shaft 6 is inserted has a tip having a diameter corresponding to the sliding bearing portion 76 inserted into the fixed side mold 81.
As shown in FIG. 9, the portion 89 corresponding to the escape portion 77 of the core 86 has a larger diameter than the portion 87 corresponding to the sliding bearing portion 76, and the boundary is a portion 87 corresponding to the sliding bearing portion. By gradually separating the cutting blade from, the portion 87 corresponding to the sliding bearing portion is smoothly connected, and the portion 89 corresponding to the escape portion has a cross-sectional shape connected by the edge 90.

  In the manufacture of the bearing house 70 using the molding die as described above, after the resin is injected into the set molding die, the movable-side die 85 is separated from the fixed-side die 81 from the parting line, whereby the small-diameter portion 72 is formed. The core 86 is extracted from the bearing house 70 remaining in the movable side mold 85 after being extracted from the fixed side mold 81. Finally, the bearing house 70 is pushed out from the movable mold 85.

  However, in the conventional bearing house 70 manufactured as described above, the accuracy of the sliding bearing portion 76 in the small-diameter portion 72 of the product is unstable, and the inner diameter of the sliding bearing portion 76 is larger than the design value, or There was a problem that the inner peripheral surface was damaged. When the sliding bearing portion 76 supports, for example, the rotating shaft 6 having a diameter of 1 mm or less, if the accuracy of the contact surface of such a relatively rotating member decreases, it may cause fluctuations in motor rotation and generation of vibration. This greatly affects motor performance and is a major cause of product failure.

Further, as a contact surface of the relatively rotating member, there is an end surface 73 at the tip of the small diameter portion 72 of the bearing house. The end surface 73 is attached to the rotary shaft 6 and faces the collar 32 that rotates together with the rotating eccentric weight 30, so that a mirror finish is desirable, but even if the corresponding surface of the mold is a mirror surface, the end surface of the product is the desired mirror surface There is also a problem that cannot be obtained.
Therefore, in view of the above-described conventional problems, an object of the present invention is to provide a coreless motor in which a stable desired accuracy is ensured on a contact surface of a relatively rotating member.

  As a result of repeated investigations on the cause of the above problems, especially in the case of slide bearings, the part corresponding to the relief part with a large core diameter is replaced with the part corresponding to the slide bearing part with a smaller diameter by the elasticity of the resin material. The inner diameter of the part corresponding to the slide bearing after pulling out should be restored to the design value after the drawing, but the edge of the boundary between the part corresponding to the clearance and the part corresponding to the slide bearing is the slide bearing It has been found that the portion corresponding to the portion is damaged to cause so-called musiness, or that the shape of the boundary portion affects the return of the inner diameter of the portion corresponding to the slide bearing portion whose diameter has been once expanded.

Furthermore, since the runner gate is opened in the radial direction of the small-diameter portion of the end face of the bearing house small-diameter portion, the resin injected from the gate must flow in the radial direction and then turn in the axial direction. In addition to the decrease in fluidity, the corners of the end surface and the outer peripheral surface of the small-diameter portion have a right-angled edge shape. It is thought that it is not supplied.
Furthermore, when using a composite material in which glass fiber or the like is mixed with resin, the fiber direction becomes random and affects the shrinkage rate of the resin, which makes it difficult to obtain a perfect circular shaft hole.

  Therefore, in the present invention of claim 1, the bearing house is fixed to one end of the housing case, and the columnar field magnet extending in the axial direction in the housing case is fixed to the other end and supported by the bearing house. A coreless having a rotor comprising a rotating shaft, a coil support fixed to one end of the rotating shaft facing the housing case, and a cylindrical coil coupled to the coil support and surrounding the outer periphery of the field magnet with a gap The bearing housing includes a small-diameter portion extending outward, and a sliding bearing portion in which shaft holes through which the rotation shaft passes along the axial center of the small-diameter portion are spaced apart from each other in the axial direction. And a clearance part larger in diameter than the inner diameter of the sliding bearing part sandwiched between the sliding bearing parts, and the boundary between the clearance part and each sliding bearing part is inclined by 30 ° or less with respect to the axial direction. It was a surface.

  According to a third aspect of the present invention, in the molding die for the bearing house, the corner portion between the surface corresponding to the end surface of the small diameter portion and the surface corresponding to the outer peripheral surface is an inclined surface or a curved surface, and corresponds to the end surface. It was assumed that there was a runway gate on the surface.

  In the first aspect of the present invention, the boundary between the shaft hole relief portion through which the rotating shaft passes and each sliding bearing portion is inclined at an angle of 30 ° or less with respect to the axial direction. The boundary between the portion corresponding to と and the portion corresponding to the relief portion is an inclined surface with a small angle. Therefore, since the sliding bearing portion is smoothly and gradually enlarged in diameter when the core is pulled out, high surface accuracy is ensured without causing damage or plastic deformation to the inner peripheral surface of the sliding bearing portion.

A third aspect of the present invention is the molding die for a bearing house according to the first aspect, further comprising a core that forms the shaft hole, wherein the core includes a portion corresponding to the escape portion, and the sliding bearing portion. And a slope portion provided at the boundary between these portions and corresponding to the slope.

Embodiments of the present invention will be described below. FIG. 1 is a longitudinal sectional view of a coreless motor according to an embodiment.
In the coreless motor 1, a bearing house 10 is fixed to an opening side which is one end of a cylindrical housing case 2, and a columnar field magnet 3 is fixed to a bottom portion which is the other end side of the housing case 2 to thereby form a housing case. 2 extends in the axial direction.

The rotor 5 includes a rotating shaft 6, a coil support 7 and a cylindrical coil 8. The rotary shaft 6 is rotatably supported by a bearing house 10, and a coil support 7 is fixed to one end of the rotary shaft 6 in the housing case 2. A cylindrical coil 8 is connected to the inner wall of the housing case 2 and a field magnet from the coil support 7. The gap between the three cases extends toward the bottom of the housing case 2. The coil support 7 is provided with a commutator 9. The commutator 9 is brought into contact with the brush 12 supported by the bearing house 10.
The other end of the rotating shaft 6 extends outward from the bearing house 10, and an eccentric weight 30 is attached to the tip thereof. On the rotating shaft 6, a collar 32 is provided between the eccentric weight 30 and the end face 21 of the bearing house.

FIG. 2 is an enlarged cross-sectional view showing details of the bearing house.
The bearing house 10 includes a large-diameter portion 11 that is fitted into the housing case 2 and a small-diameter portion 20 that extends outward from the large-diameter portion 11. The large-diameter portion 11 has a brush that can contact the commutator 9 of the rotor 5. A brush holding portion 13 for holding 12 is formed, and a commutator accommodating portion 14 for forming a contact space between the commutator 9 and the brush 12 is formed.
The small-diameter portion 20 has an end face 21 that is perpendicular to the axial direction, and has a straight portion shape with a constant diameter over a predetermined distance from the tip to the vicinity of the large-diameter portion 11. At the tip of the small-diameter portion 20, the corner portions of the end surface 21 and the outer peripheral surface 22 are inclined surfaces 23 (conical surfaces) by chamfering of 45 °. The width B of the inclined surface 23 is preferably 1/10 or more of the outer diameter of the small diameter portion 20 when viewed from the axial direction.

The shaft hole 15 penetrating to the commutator accommodating portion 14 of the small diameter portion 20 is provided with slide bearing portions 25 and 25 at both ends in the axial direction, and the section between the slide bearing portions 25 and 25 is larger than the diameter of the rotary shaft 6. The escape portion 27 has a large inner diameter. The boundary between the sliding bearing portion 25 and the relief portion 27 is an inclined surface 26 (conical surface) having an inclination of 15 ° with respect to the axial direction. The connecting portion between the inclined surface 26 and the sliding bearing portion 25 and the escape portion 27 may be curved with a predetermined R.
FIG. 3 is an enlarged view of a portion of the shaft hole extending from the sliding bearing portion 25 to the escape portion 27.

Further, the escape portion 27 is formed with a plurality of ring-shaped beads 28 at regular intervals in the axial direction. The ridge diameter of the bead 28 is slightly larger than the inner diameter of the sliding bearing portion 25, and therefore does not come into contact with the rotating shaft 6 supported by the sliding bearing portions 25, 25.
Lubricant (not shown) is held in the valleys between the beads 28 of the escape portion 27 and supplies the lubricant to the slide bearing portions 25 and 25.

FIG. 4 shows a mold used for manufacturing the bearing house 10. FIG. 4 is a cross section taken along the line BB in FIG.
The molding die 40 includes a fixed side die 41, a movable side die 60 and a core 52.
A parting line PL is set corresponding to the boundary between the large diameter portion 11 and the small diameter portion 20, the fixed side mold 41 defines the outline of the small diameter portion 20, and the movable side mold 60 defines the outline of the large diameter portion 11. To do.
The fixed-side mold 41 is mainly composed of an A-type 42 for the outer shape of the cylindrical portion of the small-diameter portion 20 and a B-type 43 mainly for the end surface portion of the small-diameter portion 20, and the B-type 43 is superimposed on the A-type 42.

  In the B-type 43, portions corresponding to the corners of the end surface 21 and the outer peripheral surface 22 of the small diameter portion 20 are inclined surfaces 46. In addition, a runner 47 for guiding the molten resin is formed in the B-type 43, and a resin injection gate 48 connected to the runner 47 is projected from the surface 44 corresponding to the end face 21 in the axial direction and opened. . A surface corresponding to the end surface 21 (hereinafter referred to as “surface corresponding to the end surface”) 44 has a mirror finish.

As shown in FIG. 5, two gates 48 are provided symmetrically on the diameter line of the surface 44 corresponding to the end surface.
In the center of the surface 44 corresponding to the end surface, a protrusion 49 having a hole 50 for inserting an alignment pin 53 described later is provided.
A resin injection gate (not shown) is also provided on the surface of the movable side mold 60 opposite to the fixed side mold 41.

The core 52 that forms the shaft hole 15 through which the rotary shaft 6 is inserted is supported by the movable die 60 so that the base corresponding to the large diameter portion 11 can be stroked, and the alignment pin 53 provided at the tip is fixed. The mold 41 is set by being inserted into the hole 50 of the protrusion 49 provided at the center of the surface 44 corresponding to the end surface.
A portion 56 (hereinafter, “a portion corresponding to the relief portion”) 56 of the core 52 is larger than a portion (hereinafter, “a portion corresponding to the slide bearing portion”) 54 corresponding to the slide bearing portion 25. It has a diameter, and its boundary is an inclined surface 55 of 15 °. A plurality of ring-shaped grooves 57 corresponding to the beads 28 are formed side by side in the axial direction in the portion 56 corresponding to the escape portion. The valley diameter of each groove 57 is larger than the diameter of the portion 54 corresponding to the slide bearing portion, and the cross-sectional shape of the groove 57 is an arc in the longitudinal sectional view of FIG.

  The manufacturing procedure of the bearing house 10 using the molding die 40 is similar to the conventional example. First, after the resin is injected into the set molding die from the gate 48 or the like, the movable side die 60 is fixed from the parting line PL. The small-diameter portion 20 is pulled out from the fixed side mold 41 by being separated from 41, and then the core 52 is pulled out from the bearing house 10 remaining in the movable side mold 60. Finally, the bearing house 10 is pushed out from the movable side mold 60.

  At the time of resin injection, the resin from the gate 48 flows in the A-type 42 along the axial direction of the core 52, and a part of the resin diverges along the inner peripheral surface 45 of the A-type 42 and conversely in the B-type 43 direction. To flow. At this time, in the B-type 43, the portions corresponding to the corners of the end surface and the outer peripheral surface other than the opening of the gate 48 are the inclined surfaces 46, so that the resin flowing along the inner peripheral surface 45 of the A-type 42 is It is smoothly guided to the surface 44 corresponding to the end surface. Since the surface 44 corresponding to the end surface has a mirror finish, the end surface 21 of the small-diameter portion 20 to be molded becomes a highly accurate mirror surface.

The embodiment is configured as described above, and includes a small-diameter portion 20 extending outward, and a slide bearing in which shaft holes 15 through which the rotating shaft 6 passes along the axial center thereof are spaced apart from each other in the axial direction. In the bearing house 10 of the coreless motor which is a clearance portion 27 having a diameter larger than the inner diameter of the sliding bearing portion sandwiched between the sliding portions 25 and 25 and the sliding bearing portion 25, 25, the clearance portion 27 and each of the sliding bearing portions 25. Since the inclined surface 26 is 15 ° with respect to the axial direction, the angle between the portion 54 corresponding to the sliding bearing portion and the portion 56 corresponding to the relief portion is 15 °. The inclined surface 55 is small.
Therefore, when the core 52 having a portion 56 corresponding to the relief portion thicker than the portion 54 corresponding to the slide bearing portion is pulled out, the diameter of the slide bearing portion 25 is smoothly and gradually increased. Therefore, the inner circumference of the slide bearing portion 25 is increased. Since the surface is not damaged and the diameter is not expanded rapidly, plastic deformation does not occur, and after passing through the portion 56 corresponding to the escape portion, the diameter is surely returned to the original diameter, and relative rotation with the rotary shaft 6 is achieved. High surface accuracy of the sliding bearing portion 25 is ensured.

  In addition, since a plurality of ring-shaped beads 28 having a mountain diameter larger than the inner diameter of the slide bearing portion 25 are formed in the escape portion 27 of the bearing house 10, a certain amount of oil leaks from the slide bearing portion 25 to the outside. Even in such a case, the lubricant is held in the escape portion 27 for a long period of time, and the lubricant is stably supplied to the sliding bearing portion 25, so that the life of the motor is maintained for a long time.

Further, in the molding die 40 of the bearing house 10 having the shaft hole 15 through which the rotary shaft 6 passes along the axial center of the small diameter portion 20 extending outward, the runner 47 is provided on the surface 44 corresponding to the end surface of the small diameter portion. On the other hand, since the corner portion of the surface 44 corresponding to the end surface 21 of the small diameter portion and the surface corresponding to the outer peripheral surface 22 (inner peripheral surface 45) is the inclined surface 46, the resin injected from the gate 48 Is smoothly guided to the surface 44 corresponding to the end surface. Thereby, transferability improves and the end surface 21 of a small diameter part can be made into a mirror surface finish, and the contact friction with the weight 30 attached to the rotating shaft 6 or the collar 32 can be reduced.
Further, since the basic flow of the resin from the gate 48 is directed in the axial direction, even when the glass fiber for reinforcement is included in the resin, the glass fiber is generally axially aligned with the flow of the resin. To align. Therefore, since the shrinkage direction of the resin is uniform, the roundness of the shaft hole of the sliding bearing portion 25 and the like is improved and high hole accuracy is obtained.
Further, the fixed-side die 41 for the small-diameter portion is divided into an A-type 42 and a B-type 43 in the vicinity of the inclined surface 46, so that maintenance and replacement of the “surface corresponding to the end face” 44 having a mirror-finished portion can be performed. Easy and reduces maintenance costs.

In the embodiment, the boundary between the portion 54 corresponding to the plain bearing portion of the core 52 and the portion 56 corresponding to the relief portion is the inclined surface 55 of 15 °, but is not limited to this, and the boundary is 30 ° or less. If it is an inclined surface, damage and plastic deformation of the inner peripheral surface of the sliding bearing portion 25 can be suppressed.
Further, in the molding die 40 of the bearing house, the peripheral corner portion of the surface 44 corresponding to the end surface of the small diameter portion is the inclined surface 46 by chamfering, but it may be a curved surface by R.

It is a longitudinal section of the coreless motor concerning an embodiment. It is an expanded longitudinal cross-sectional view which shows the detail of a bearing house. It is the elements on larger scale of a shaft hole. It is a longitudinal cross-sectional view which shows the shaping | molding die used for manufacture of a bearing house. It is A arrow directional view in FIG. It is a longitudinal cross-sectional view which shows the prior art example of a coreless motor. It is an expanded sectional view which shows the bearing house in a prior art example. It is a figure which shows the shaping | molding die of the conventional bearing house. It is the elements on larger scale of the core in the conventional shaping | molding die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coreless motor 2 Housing case 3 Field magnet 5 Rotor 6 Rotating shaft 7 Coil support 8 Cylindrical coil 9 Commutator 10 Bearing house 11 Large diameter part 12 Brush 13 Brush holding part 14 Commutator accommodating part 15 Shaft hole 20 Small diameter part 21 End surface 22 outer peripheral surface 23 inclined surface 25 plain bearing portion 26 inclined surface 27 escape portion 28 bead 30 eccentric weight 32 collar 40 molding die 41 fixed side die 42 A type 43 B type 44 surface 45 corresponding to the end surface 45 inner peripheral surface 46 inclined surface 47 Runway 48 Gate 49 Protruding part 50 Hole 52 Core 53 Positioning pin 54 Part corresponding to the sliding bearing part 55 Inclined surface 56 Part corresponding to the escape part 57 Groove 60 Movable side type PL parting line

Claims (3)

A bearing house is fixed to one end of the housing case, and a cylindrical field magnet extending in the axial direction in the housing case is fixed to the other end.
A rotating shaft supported by the bearing house, a coil support fixed to one end of the rotating shaft facing the housing case, and a cylindrical coil coupled to the coil support and surrounding the outer periphery of the field magnet with a gap A rotor consisting of
The bearing house includes a small-diameter portion extending outward, and a slide bearing portion provided with shaft holes through which the rotation shaft passes along the axial center of the small-diameter portion, spaced apart from each other in the axial direction, It is composed of a clearance portion that is sandwiched between the sliding bearing portions and has a diameter larger than the inner diameter of the sliding bearing portion, and the boundary between the clearance portion and each sliding bearing portion is an inclined surface of 30 ° or less with respect to the axial direction. A coreless motor characterized by that. The coreless motor according to claim 1, wherein a plurality of ring-shaped beads having a mountain diameter larger than an inner diameter of the sliding bearing portion are formed in the relief portion of the bearing house. A core that forms the shaft hole;
The core includes a portion corresponding to the escape portion, a portion corresponding to the sliding bearing portion, and an inclined portion provided at a boundary between these portions and corresponding to the inclined surface.
The mold for molding a bearing house according to claim 1.

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