JP5095329B2 - Motor and blower fan - Google Patents

Description

  The present invention relates to a motor and a blower fan bearing structure having high impact resistance.

  Conventionally, blower fans have been used for cooling electronic devices and the like. Conventional electronic devices are often used in a state where they are installed on a table like a personal computer, for example. However, in recent years, products that are small and easy to carry have been developed as electronic devices. An electronic device that is easy to carry is required to have a higher impact resistance due to dropping or the like than a desktop electronic device. That is, higher impact resistance than before is also required for the blower fan mounted inside the electronic device.

  The main use of the conventional blower fan is for cooling, but in recent years, the use of the cooling fan is diversified. For example, there are an in-vehicle blowing fan, a notebook computer cooling fan, and the like, and a structure having impact resistance has become indispensable.

  Ball bearings are used as bearing members for models that require a long life among blower fans. The ball bearing is mainly composed of an outer ring, an inner ring, and a plurality of balls that roll between them. A plurality of balls roll while making point contact between the inner ring and the outer ring, and the outer ring rotates relative to the inner ring. For example, in a sliding bearing, high dynamic friction is generated by sliding on the bearing surface, and energy loss occurs. Further, in the fluid dynamic pressure bearing, since dynamic pressure is generated on the bearing surface, energy loss occurs. However, in the ball bearing, the dynamic friction is small and no dynamic pressure is generated due to the above-described configuration, so that the energy loss is small compared to the slide bearing and the fluid dynamic pressure bearing. However, since the ball is in point contact with the inner ring and the outer ring, the ball, the outer ring, and the inner ring are liable to be damaged during an impact such as dropping. When scratches are generated, noise or the like is generated during rotation.

  The following patent documents are disclosed as a bearing structure used for a conventional blower fan.

  For example, in the axial fan described in Patent Document 1, a ball bearing is used as a bearing member, and in order to avoid a creep phenomenon of the ball bearing that depends on operational vibration, an outer ring of the ball bearing and a bearing box It is disclosed that a hard rubber is interposed therebetween.

JP 2000-192893

  By the way, in recent blower fans, as described above, impact resistance against impacts caused by dropping or the like is required.

  In the axial fan described in Patent Document 1, the creep phenomenon of the ball bearing, that is, the outer ring of the ball bearing can prevent relative rotation with respect to the bearing housing. Further, by interposing a hard rubber between the ball bearing and the bearing housing, it is possible to buffer the impact from the outside with the hard rubber. Therefore, it was possible to satisfy the impact resistance standards that have been required so far. However, it is becoming difficult to satisfy the impact resistance standards required for recent blower fans. For this reason, it is necessary to constitute a blower fan having a bearing structure with higher impact resistance.

  The present invention has been made in view of the above problems, and an object of the present invention is to obtain a bearing structure for preventing damage to a ball bearing from an impact caused by dropping or the like in a blower fan.

  The present invention has been made in view of the above prior art. That is, the motor according to claim 1 of the present invention is a motor, and includes a rotor portion having a shaft and a rotor magnet that rotates about a central axis, and a rotor magnet that is disposed to face the rotor magnet. A stator portion that generates torque between the rotor portion, a base portion that is supported by the stator portion and disposed below the rotor portion in the direction of the central axis, and the center portion is centered on the central axis A substantially cylindrical bearing holding portion, and a pair of ball bearings spaced from each other in the direction of the central axis and inserted through the inner ring, and the shaft includes the pair of ball bearings. There is provided a movement restricting portion for restricting relative movement of the ball bearing with respect to the inner ring of the ball bearing from the side opposite to the direction in which the ball bearings are separated from each other. Inside of the bearing holder, characterized in that the pair of elastic members holding surface for supporting the pair of ball bearings via the elastic member between the outer ring of the ball bearing is configured.

  According to a second aspect of the present invention, the motor according to the second aspect is the motor according to the first aspect, wherein a pair of movement restricting surfaces are formed such that a gap between the pair of ball bearings is smaller than the pair of elastic member holding surfaces. It is characterized by being.

  According to a third aspect of the present invention, the motor according to the third aspect is the motor according to the first or second aspect, wherein the movement restricting portion located below the central axis is fixed in the vicinity of the tip of the shaft. It is a retaining member.

  According to a fourth aspect of the present invention, the motor according to the fourth aspect is the motor according to any one of the first to third aspects, wherein the movement restricting portion located above the central axis direction is a part of the rotor portion. It is characterized by that.

  According to a fifth aspect of the present invention, the motor according to the fifth aspect is the motor according to the fourth aspect, wherein the pair of movement restricting portions are separated so that an elastic force acts on at least one of the pair of elastic members. It is characterized by being arranged.

  According to a sixth aspect of the present invention, the motor according to the sixth aspect is the motor according to the fifth aspect, wherein substantially the same elastic force is generated in the pair of elastic members when the rotor portion is stopped. It is characterized by being.

  According to a seventh aspect of the present invention, the motor according to the seventh aspect is the motor according to the fifth aspect, wherein the elastic member positioned downward in the central axis direction is a preload spring.

  The motor according to claim 8 is the motor according to claim 7, wherein the elastic member positioned above the central axis direction has a larger elastic force than the preload spring. And

  According to the present invention, the motor according to claim 9 is the motor according to claim 1 or 2, wherein a ring-shaped retaining member that is fixed near the tip of the shaft is fixed, and the lower side in the central axis direction The movement restricting portion located at a position is a preload spring interposed between the inner ring of the ball bearing located below the central axis and the retaining member.

  According to a tenth aspect of the present invention, the motor according to the tenth aspect is the motor according to the first or second aspect, wherein the movement restricting portion located above the central axis direction is located above the rotor portion and the central axis direction. The preload spring is interposed between the ball bearing and the inner ring.

  According to the present invention, the motor according to claim 11 is the motor according to any one of claims 1 to 10, wherein the elastic member is at a maximum when a load is applied to the ball bearing by the movement restricting portion. Before the deflection is reached, the inner ring of the ball bearing is in contact with the movement restricting surface.

  The present invention provides a blower fan according to a twelfth aspect of the present invention, in which the motor according to any one of the first to eleventh aspects is mounted, and the rotor portion rotates around the central axis. A blower fan comprising a plurality of blades for generating an air flow.

  According to the motor of the present invention, since the outer ring of the ball bearing is supported by the elastic member, the impact transmitted to the ball bearing is buffered by the elastic member when an impact is applied to the motor. Further, when an impact is applied to the motor and the outer ring of the ball bearing presses the elastic member, the inner ring of the ball bearing comes into contact with the movement restricting surface before the elastic member reaches the elastic limit. As a result, an inertia force due to the impact acts on the outer ring of the ball bearing when an impact is applied to the motor, and a reaction force from the elastic member acts on the inner ring in a direction opposite to the inertia force. Here, when the elastic member reaches the elastic limit, the reaction force by the elastic member increases rapidly. Therefore, when the inner ring comes into contact with the movement restricting surface, the inertial force acting on the inner ring can be suppressed, and at the same time, a sudden increase in the reaction force due to the elastic member can be prevented. If a large force acts between the inner ring and the outer ring in opposite directions, the ball is more likely to be damaged, which causes noise. According to the present invention, it is possible to prevent the ball bearing from being damaged.

  Hereinafter, a centrifugal fan according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. In the embodiment of the present invention, the vertical direction of each drawing is referred to as “vertical direction” for convenience, but the direction and the direction of gravity in the actual attachment state are not limited.

  FIG. 1 is a diagram showing a configuration of a centrifugal fan 1 according to a first embodiment of the present invention, and shows a longitudinal sectional view cut along a plane including a central axis J1.

  The blower fan according to the first embodiment of the present invention will be described. Here, a centrifugal fan is used as an example of the blower fan. As shown in FIG. 1, the centrifugal fan 1 includes an impeller unit 2 that generates an air flow by rotating, and a motor unit 3 that is connected to the impeller unit 2 and rotates around the central axis J <b> 1. The impeller unit 2 and the motor unit 3 are accommodated in the casing 10. As shown in FIG. 1 and FIG. 2, the casing 10 is assembled by attaching a cover portion 12 having an intake port 121 to the side wall portion 101 of the casing 10, and surrounds the periphery of the impeller portion 2. (That is, the flow direction is formed in the air flow generated by the rotation of the impeller 2 and the air is discharged to the outside). The centrifugal fan 1 is used, for example, as an electric fan for cooling electrical products and electronic devices.

  As shown in FIG. 1, the casing 10 includes a base portion 102 and a side wall portion 101. At the center of the base portion 102, a bearing holding portion 310 is fixed so as to be coaxial with the rotation axis of the impeller portion 2, that is, the central axis J1. Further, the side wall portion 101 is formed so as to protrude continuously from the outer peripheral portion of the base portion 102 toward the upper side in the direction of the central axis J1. As shown in FIG. 1, an exhaust port 103 is formed in the side wall portion 101, and an air flow generated by the rotation of the impeller 2 is discharged from the exhaust port 103 to the outside of the centrifugal fan 1. As described above, the cover portion 12 is attached to the upper end of the side wall portion 101. The intake port 121 formed in the cover part 12 is substantially circular. When the cover portion 12 is attached to the casing 10, the center of the air inlet 121 is configured to overlap the central axis J1. However, the center of the intake port 121 and the central axis J1 do not necessarily overlap, and the center of the intake port 121 may be shifted from the central axis J1.

  The shape of the casing 10 is formed in a cochlear shape when viewed from above the central axis J1 (not shown). Between the outer periphery of the impeller 2 and the inner peripheral surface of the side wall portion 101, a flow path for airflow generated by the rotation of the impeller is formed. The flow path is formed so that the cross-sectional area of the cross section of the flow path cut by a plane including a line segment parallel to the radial direction gradually increases from the upstream toward the exhaust port 103. However, the cross-sectional area of the flow path may be substantially the same from the upstream toward the exhaust port 103 in consideration of the size of the centrifugal fan and the air flow characteristics, and the shape of the flow path is not limited to the above. By forming the casing shape into a cochlea shape, it is possible to rectify the air flow generated by the rotation of the impeller 2 and to adjust the flow velocity direction of the air flow from the exhaust port. It is also possible to improve the pressure difference (static pressure) between the intake port 121 and the exhaust port side 103.

  As shown in FIG. 1, the motor unit 3 is an outer rotor type (a type in which a rotor magnet 322 included in the motor is positioned radially outward from the stator unit 31). The motor unit 3 mainly includes a rotor unit 32 that is a rotating body, a stator unit 31 that is a stationary body, and a bearing unit. The rotor part 32 is rotatably supported by a bearing part described later with respect to the stator part 31. The configuration of the bearing portion will be described in detail later.

  The stator part 31 is fixed to the outer surface of a bearing holding part 310 in which a bearing part described later is accommodated. The stator portion 31 mainly includes a stator core 311, first and second insulators 312 a and 312 b, a coil 313, and a circuit board 314.

  The stator core 311 is configured by stacking a plurality of stator laminations formed of thin magnetic materials. In particular, the centrifugal fan 1 of the present embodiment used for cooling electronic devices employs a single-phase bipolar or a two-phase unipolar as a driving method. In single-phase bipolar and two-phase unipolar, a 4-pole stator core is used. Therefore, the stator core 311 in this embodiment is configured by an annular core back portion and four magnetic pole teeth. The magnetic pole teeth 4 protrude outward from the outer surface of the core back portion in the radial direction, and are arranged in the circumferential direction with the central axis J1 as the center.

  The periphery of the stator core 311 is covered with an insulator 312 except for the outer surface and the inner surface. The first insulator 312 a covers the stator core 311 from above, and the second insulator 312 b covers the stator core 311 from below. A coil 313 is formed by winding a copper wire around the magnetic pole teeth of the stator core 311 via an insulator 312.

  A circuit board 314 supported by being connected to the second insulator 312b is disposed below the stator core 311. The circuit board 314 includes a board and circuit components. A conductive pattern formed of copper foil is printed on the substrate so that a control circuit is configured by mounting circuit components. Circuit components are mounted on the substrate, and the control circuit and the end of the copper wire constituting the coil 313 are electrically connected to the circuit substrate 314.

  The rotor part 32 includes an impeller 2, a rotor yoke 321, a rotor magnet 322, and a shaft 323. The impeller 2 includes a covered cylindrical cup portion 21, an annular hub 22, and a plurality of wings 23.

  A shaft 323 is fixed at the center of the cup portion 21 so as to be coaxial with the central axis J1. The impeller 2 rotates around the central axis J1 with the shaft 323 as a rotation axis. A cylindrical rotor yoke 321 is fixed to the inner surface of the cylindrical portion of the cup portion 21. Further, an annular rotor magnet 322 is fixed to the inner surface of the rotor yoke 321. The rotor magnet 322 is magnetized so that a plurality of magnetic poles are alternately arranged in the circumferential direction. The rotor yoke 321 is made of a magnetic material. Since the rotor yoke 321 is configured, the magnetic field formed by the rotor magnet 322 can be prevented from leaking from the blower fan 1 to the outside. The rotor magnet 322 is disposed so as to face the outer peripheral surface of the stator core 311 in the radial direction. Therefore, when a current is supplied to the circuit board 314 from an external power source, a magnetic field is generated in the stator core 311, and the central axis J <b> 1 is centered by the interaction between the magnetic field and the magnetic field formed in the rotor magnet 322. Torque is generated. Along with this, the impeller 2 rotates around the central axis J1.

  Next, the configuration of the bearing portion will be described. FIG. 2 is a diagram showing the configuration of the bearing portion of the blower fan 1 according to the first embodiment of the present invention, and shows a longitudinal sectional view cut along a plane including the central axis J1. The shaft 323 has an upper end fixed to the cup portion 21 and protrudes downward from the cup portion 21. Ball bearings 315 and 316 are fixed to the inner surface side of the bearing holding portion 310. The shaft 323 is rotatably supported by being inserted into the ball bearings 315 and 316. Near the upper end of the shaft 323, a preload spring 317 is attached to the upper side of the ball bearing 315 in the central axis J1 direction. A retaining member 318 is attached in the vicinity of the lower end of the shaft 323 so that the shaft 323 does not come off from the ball bearing 316. Since the retaining member 318 is configured to be displaced in the central axis J1 direction with respect to the preload spring 317, a preload is applied to the ball bearings 315 and 316 by the preload spring 317. As a result, the ball bearings 315 and 316 and the shaft 323 are held in the correct positions.

  The bearing portion will be further described in detail. The upper ball bearing 315 includes an outer ring 3151, an inner ring 3152, and a plurality of balls 3153 that are rolling elements. The outer ring 3151 has a raceway surface on which a plurality of balls 3153 roll on the inner peripheral surface. The inner ring 3152 has a raceway surface on which a plurality of balls 3153 roll on the outer peripheral surface. Although not shown, a retainer called a retainer is configured so that the plurality of balls 3153 do not come off the raceway surface. Therefore, the outer peripheral surface of the outer ring 3151 is supported by the bearing holder 310 in the ball bearing 315. A shaft 323 is inserted into the inner peripheral surface of the inner ring 3152. The lower ball bearing 316 has the same configuration.

  As described above, the ball bearings 315 and 316 need to be preloaded. Therefore, the preload applied to the ball bearing 315 will be described in detail below. A play is formed between the outer ring 3151 and the inner ring 3152 of the ball bearing 315 in the direction of the central axis J1. When play in the direction of the central axis J1 is configured between the outer ring 3151 and the inner ring 3152, there is a possibility that abnormal noise may be generated due to vibration and resonance in the direction of the central axis J1. Moreover, there is a possibility that a desired bearing life cannot be obtained. Here, a force is applied to the inner ring 3152 by the preload spring 317 toward the lower side in the central axis J1 direction with respect to the outer ring 3151 supported by the bearing holder 310. As a result, a preload in the direction of the central axis J1 is applied between the outer ring 3151 and the inner ring 3152. Therefore, the track on which the plurality of balls 3153 roll with respect to the raceway surface of the outer ring 3151 and the track on which the plurality of balls 3153 roll with respect to the raceway surface of the inner ring 3152 are stabilized. Since the retaining member 318 is fixed near the lower end of the shaft 323, the elastic force generated by the preload spring 317 applies preload between the outer ring 3161 and the inner ring 3162 of the lower ball bearing 316 in the same manner as the upper ball bearing 315. It is possible to grant. Therefore, the ball bearings 315 and 316 can supply stable rotation to the motor unit 3.

  Next, the support in the center axis J1 direction of the outer rings 3151 and 3161 of the ball bearings 315 and 316 will be described. Here, the description will be given focusing on the upper ball bearing 315. As shown in FIG. 2, an annular small-diameter cylindrical portion 3101 is formed on the inner side surface of the bearing holding portion 310 so as to protrude toward the central axis J1. Here, the inner diameter dimension of the small diameter cylindrical portion 3101 is larger than the outer diameter of the shaft 323, and when the shaft 323 is inserted into the bearing holding portion 310, the small diameter cylindrical portion 3101 and the shaft 323 are not in contact with each other. An elastic member 319 is disposed radially outward of the upper end surface of the small diameter cylindrical portion 3101. That is, the elastic member 319 is interposed between the upper end surface of the small diameter cylindrical portion 3101 and the outer ring 3151 of the ball bearing 315. Thus, in the ball bearing 315, when an impact in the direction of the central axis J1 is applied to the rotor portion 32 due to dropping or the like, the inner ring 3152 is absorbed by the preload spring 317 and the outer ring 3151 is absorbed by the elastic member 319, so that the rotor The impact applied to the portion 32 does not reach the outer ring 3151 and the inner ring 3152 directly. The small diameter cylindrical portion 3101 is cylindrical in the present embodiment, but a plurality of convex portions project from the inner peripheral surface of the bearing holding portion 310 toward the central axis J1, thereby forming the small diameter cylindrical portion. The same effect as 3101 can be exhibited.

  When the outer ring 3152 is directly supported by the bearing holding portion 310 without the elastic member 319, when an impact is applied to the rotor portion 32, the preload spring 317 exceeds the elastic limit, and the rotor portion 32. May directly contact the inner ring 3152 of the ball bearing 315. In this case, there is a possibility that the impact may directly reach a plurality of balls 3153 interposed between the outer ring 3151 and the inner ring 3152. When the impact reaches a plurality of balls 3153, the surface of the balls 3153 may be damaged, which may cause abnormal noise during rotation. However, in the above structure, even if an impact is applied to the rotor portion 32, the impact does not easily reach the ball bearing 315.

  The same applies to the lower ball bearing 316 with respect to the above configuration. However, in the lower ball bearing 316, the preload spring 317 is not configured, and the inner ring 3162 is supported upward in the central axis J1 direction by a retaining member 318 fixed near the lower end of the shaft 323.

  As the elastic member 319, a coil spring may be used similarly to the preload spring. Moreover, you may comprise with materials which have elasticity, such as rubber | gum. The elastic member 319 may be selected so as to obtain a desired elastic force according to the design, and the material and shape used are not limited. In the first embodiment, since the elastic member 319 is used to cushion the impact, it is preferable that the preload spring 317 has a smaller Young's modulus than the elastic member 319. Even if an impact occurs in the upper or lower direction of the central axis J1 direction with respect to the rotor portion 32, the two elastic members 319 should have the same Young's modulus in order to exhibit the same buffering effect. desirable.

  In the radially inner side of the upper end surface of the small-diameter cylindrical portion 3101, as shown in FIG. 2, an annular convex portion protrudes toward the upper side in the central axis J <b> 1 direction (hereinafter referred to as an annular shape). The upper end surface of the convex portion is referred to as a movement restricting surface 3102). In addition, an annular convex portion is also formed so as to protrude downward in the central axis J1 direction on the radially inner side of the lower end surface of the small diameter cylindrical portion 3101 (hereinafter, the lower end surface of the annular convex portion is also defined). This is referred to as a movement restricting surface 3103.) The movement restricting surface 3102 is formed below the upper end surface of the elastic member 319 in the central axis J1 direction with the upper end surface of the small-diameter cylindrical portion 3101 as a reference surface. Virtually, when pressure is applied toward the lower side in the central axis direction with respect to the upper end surface of the elastic member 319, the elastic member 319 is elastic (that is, the force and the displacement of the pressure surface of the elastic member 319 are proportional). Relationship). If pressure is continuously applied, the elastic member 319 will not bend. That is, since the elastic member 319 in this state exceeds the elastic limit in the direction of compression, it is considered that there is almost no buffering effect against an external impact. Therefore, the movement restricting surface 3102 is disposed on the upper side in the direction of the central axis J1 from the height that becomes the elastic limit when the elastic member 319 is pressurized.

  With the above configuration, when an impact is applied to the rotor portion 32 toward the lower side in the central axis J1 direction, the preload spring 317, the inner ring 3152, the plurality of balls 3153, the outer ring 3151, and the elastic member 319 are sequentially arranged from the rotor portion 32. Shock is transmitted. Here, the elastic member 319 bends downward in the direction of the central axis J1 due to the stress caused by the impact. Therefore, since the inner ring 3152 is configured to contact the position restricting surface 3102 before the elastic member 319 reaches the elastic limit, the plurality of balls 3153 formed between the inner ring 3152 and the outer ring 3151 are formed. Can be suppressed.

  Also in the lower ball bearing 316, when an impact is applied toward the upper side in the central axis J1 direction with respect to the rotor portion 32, a retaining member 317, an inner ring 3162, a plurality of balls 3163, an outer ring 3161, an elastic member from the rotor portion 32. The impact is transmitted in the order of 319. Here, the elastic member 319 bends upward in the central axis J1 direction due to the stress caused by the impact. Therefore, since the inner ring 3162 is configured to contact the position restricting surface 3103 before the elastic member 319 reaches the elastic limit deflection, the plurality of balls 3163 formed between the inner ring 3162 and the outer ring 3161 are formed. Can be suppressed.

  Next, a blower fan according to a second embodiment of the present invention will be described. The centrifugal fan according to the second embodiment has the same configuration as the centrifugal fan 1 shown in FIG. 1 and FIG. 2 except that the configuration of the bearing portion is partially different. The other components are denoted by the same reference numerals.

  FIG. 3 is a view showing the configuration of the bearing portion of the centrifugal fan 1A according to the second embodiment of the present invention, and shows a longitudinal sectional view cut along a plane including the central axis J1. The shaft 323 has an upper end fixed to the cup portion 21 and protrudes downward from the cup portion 21. Ball bearings 315 and 316 are fixed to the inner surface side of the bearing holding portion 310. The shaft 323 is rotatably supported by being inserted into the ball bearings 315 and 316. A retaining member 318 is attached in the vicinity of the lower end of the shaft 323 so that the shaft 323 does not come off from the ball bearing 316. A preload spring 317A is attached between the retaining member 318 and the ball bearing 316. Since the retaining member 318 is configured to be displaced in the central axis J1 direction with respect to the preload spring 317A, preload is applied to the ball bearings 315 and 316 by the preload spring 317A. As a result, the ball bearings 315 and 316 and the shaft 323 are held in the correct positions.

  A force is applied to the inner ring 3162 toward the upper side in the central axis J1 direction by the preload spring 317A with respect to the outer ring 3161 supported by the bearing holder 310. As a result, a preload in the direction of the central axis J1 is applied between the outer ring 3161 and the inner ring 3162. Therefore, the track on which the plurality of balls 3163 roll with respect to the raceway surface of the outer ring 3161 and the track on which the plurality of balls 3163 roll with respect to the raceway surface of the inner ring 3162 are stabilized. Near the upper end of the shaft 323, a boss portion 211 configured as a part of the cup portion 21 is in contact with the inner ring 3152 in the direction of the central axis J1. Therefore, the elastic force generated by the preload spring 317A can apply a preload between the outer ring 3151 and the inner ring 3152 of the upper ball bearing 315 in the same manner as the lower ball bearing 316. Therefore, the ball bearings 315 and 316 can supply stable rotation to the motor unit 3A. Also in the second embodiment, the same effect as in the first embodiment is exhibited.

  Next, a blower fan according to a third embodiment of the present invention will be described. The centrifugal fan according to the third embodiment has the same configuration as the centrifugal fan 1 shown in FIG. 1 and FIG. 2 except that the configuration of the bearing portion is partially different. The other components are denoted by the same reference numerals.

  FIG. 4 is a diagram showing the configuration of the bearing portion of the centrifugal fan 1B according to the third embodiment of the present invention, and shows a longitudinal sectional view cut along a plane including the central axis J1. The shaft 323 has an upper end fixed to the cup portion 21 and protrudes downward from the cup portion 21. Ball bearings 315 and 316 are fixed to the inner surface side of the bearing holding portion 310. The shaft 323 is rotatably supported by being inserted into the ball bearings 315 and 316. In the third embodiment, unlike the first and second embodiments, no preload spring is configured. However, as described in the description of the first embodiment, in the bearing structure using the ball bearing, it is necessary to generate a preload between the inner ring and the outer ring in the direction of the central axis J1. A method for generating the preload will be described later.

  As shown in FIG. 2, an annular small-diameter cylindrical portion 3101 is formed on the inner side surface of the bearing holding portion 310 so as to protrude toward the central axis J1. Here, the inner diameter dimension of the small diameter cylindrical portion 3101 is larger than the outer diameter of the shaft 323, and when the shaft 323 is inserted into the bearing holding portion 310, the small diameter cylindrical portion 3101 and the shaft 323 are not in contact with each other. An elastic member 319 is disposed radially outward of the upper end surface of the small diameter cylindrical portion 3101. That is, the elastic member 319 is interposed between the upper end surface of the small diameter cylindrical portion 3101 and the outer ring 3151 of the ball bearing 315. Thus, in the ball bearing 315, when an impact in the direction of the central axis J1 is applied to the rotor portion 32 due to dropping or the like, the inner ring 3152 is absorbed by the preload spring 317 and the outer ring 3151 is absorbed by the elastic member 319, so that the rotor The impact applied to the portion 32 does not reach the outer ring 3151 and the inner ring 3152 directly. The small diameter cylindrical portion 3101 is cylindrical in the present embodiment, but a plurality of convex portions project from the inner peripheral surface of the bearing holding portion 310 toward the central axis J1, thereby forming the small diameter cylindrical portion. The same effect as 3101 can be exhibited.

  A retaining member 318 is attached in the vicinity of the lower end of the shaft 323 so that the shaft 323 does not come off from the ball bearing 316. Further, a boss portion 211 configured as a part of the cup portion 21 is in contact with the inner ring 3152 in the direction of the central axis J1 near the upper end of the shaft 323.

  Next, the support in the center axis J1 direction of the outer rings 3151 and 3161 of the ball bearings 315 and 316 will be described. Here, the description will be given focusing on the upper ball bearing 315. As shown in FIG. 2, an annular small-diameter cylindrical portion 3101 is formed on the inner side surface of the bearing holding portion 310 so as to protrude toward the central axis J1. An elastic member 319 is disposed radially outward of the upper end surface of the small diameter cylindrical portion 3101. That is, the elastic member 319 is interposed between the upper end surface of the small diameter cylindrical portion 3101 and the outer ring 3151 of the ball bearing 315. Thus, in the ball bearing 315, when an impact in the direction of the central axis J1 is applied to the rotor portion 32 due to dropping or the like, the inner ring 3152 is absorbed by the preload spring 317 and the outer ring 3151 is absorbed by the elastic member 319, so that the rotor The impact applied to the portion 32 does not reach the outer ring 3151 and the inner ring 3152 directly.

  With the above method, the outer ring 3151, 3161 and the inner ring 3152, 3162 are restricted from moving in the direction of the central axis J1. At this time, in the method of restricting movement of the outer rings 3151 and 3161, the span in the direction of the central axis J1 of the boss portion 211 and the retaining member is set so that elastic force is generated in the elastic member 319 when the rotor portion 32 is stationary. The That is, the span between the lower end of the boss portion 211 and the retaining member 318 is smaller than the span at the natural length of the upper end surface and the lower end surface of the elastic member 319 disposed at the upper end and the lower end of the small diameter cylindrical portion 3101. Is set.

  With the above configuration, an elastic force is generated in the elastic member 319, and this elastic force serves as a preload generated between the outer ring and the inner ring of the ball bearing. As a result, the ball bearings 315 and 316 and the shaft 323 are held in the correct positions.

  A force is applied to the inner ring 3152 by the elastic member 319 toward the upper direction in the central axis J1 with respect to the outer ring 3151 supported by the bearing holder 310. As a result, a preload in the direction of the central axis J1 is applied between the outer ring 3151 and the inner ring 3152. Therefore, the track on which the plurality of balls 3153 roll with respect to the raceway surface of the outer ring 3161 and the track on which the plurality of balls 3153 roll with respect to the raceway surface of the inner ring 3152 are stabilized. A preload is similarly applied to the lower ball bearing 316. Therefore, the ball bearings 315 and 316 can supply stable rotation to the motor unit 3A. In the third embodiment, the same effects as in the first and second embodiments are exhibited.

  As described above, the centrifugal fans of the first, second, and third embodiments have been described. However, the present invention is not limited to the above-described embodiments, and various modifications can be made.

As long as the outer ring of the ball bearing is supported by the elastic member, the method for applying the preload is not limited to the above. In the above-described embodiment, the centrifugal fan is used as the blower fan. However, the blower fan is not limited to the centrifugal fan, and can be used for an axial fan that generates an air flow in the central axis J1 direction, for example. It is a bearing structure. Furthermore, the bearing structure of the above embodiment can be employed as long as it is a motor having a bearing structure using a ball bearing as well as a blower fan.

It is sectional drawing which shows the structure of the centrifugal fan 1 which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the bearing part of the centrifugal fan 1 which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the bearing part of 1 A of centrifugal fans which concern on the 2nd Embodiment of this invention. It is sectional drawing which shows the bearing part of the centrifugal fan 1B which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Centrifugal fan 10 Casing 101 Side wall part 102 Base part 103 Exhaust port 12 Cover part 121 Inlet port 2 Impeller 21 Cup part 211 Through-hole 22 Hub 23 Blade 231 Main wing 232 Second wing 3 Motor part 31 Stator part 310 Bearing holding part 3101 Small diameter cylindrical portion 3102 Movement restricting surfaces 315, 316 Ball bearings 3151, 3161 Outer rings 3152, 3162 Inner rings 3153, 3163 Balls 314 Circuit board 317 Preload spring 318 Holding member
319 Elastic member

Claims (6)

A motor,
A rotor portion having a shaft and a rotor magnet and rotating around a central axis;
A stator portion that is arranged to face the rotor magnet and generates torque with the rotor magnet;
A base portion supported by the stator portion and disposed below the rotor portion in the central axis direction;
A substantially cylindrical bearing holding portion configured around the central axis at the center of the base portion;
A pair of ball bearings spaced apart in the direction of the central axis and disposed through the inner ring, and
With
The shaft is provided with a movement restricting portion that restricts relative movement of the pair of ball bearings with respect to the inner ring of the ball bearing from the side opposite to the direction in which the pair of ball bearings are separated from each other.
Inside of the bearing holder, a pair of elastic members holding surface for supporting the pair of ball bearings through the respective elastic members to the end face opposite to the movement restricting portion in the outer ring of the ball bearing is formed In addition, a pair of movement restricting surfaces are configured to come into contact with the end surface of the inner ring of the ball bearing opposite to the movement restricting portion before the deflection in the central axis direction of the elastic member reaches the elastic limit. A motor characterized by having The movement restricting portion is located in the central axial direction downward, the motor according to claim 1 wherein a ring-shaped retaining member which is fixed near the shaft distal end. The movement restricting portion located below the central axis direction is interposed between a ring-shaped retaining member fixed near the tip of the shaft, and the ball bearing located below the central axial direction. The motor according to claim 1, comprising a preload spring . Claim 1, wherein the movement limiting portion positioned in the central axis direction upwards is preload spring which is interposed between the inner race of the ball bearing is located in the central axis direction above said rotor portion The motor described in . 2. When the load is applied to the ball bearing by the movement restricting portion, the inner ring of the ball bearing comes into contact with the movement restricting surface before the elastic member reaches maximum deflection . 4. The motor according to any one of 4 above . A blower fan equipped with the motor according to any one of claims 1 to 5 ,
The blower fan, wherein the rotor portion includes a plurality of blades that generate an air flow by rotating about the central axis.

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