JP2005256705A - Elongated centrifugal fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elongated centrifugal fan of novel structure further reducible in radial dimension. <P>SOLUTION: An impeller 12 having a blade part 14 with a plurality of elongate blades arranged at predetermined spaces along a circumferential direction, and a motor 13 rotationally driving the impeller 12, are disposed in a line in an axial direction. The diameter of the impeller 12 is 25 mm or less, and a radius r of the impeller 12 and its axial length h satisfies the relation of 2r≤h≤20r. Out of members constituting the motor 13, a turning force generating part 13a having an armature 21 and a field magnet 22, and a bearing part 13b for holding a rotating member 12 rotatably to a fixed member 23, are arranged in a line in the axial direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an elongate centrifugal fan for cooling built in an electronic device and a motor thereof.

  In recent years, cooling fans built in electronic devices such as personal computers have become smaller and thinner. Conventionally, an axial flow type cooling fan is used in many electronic devices because the axial flow type fan has a structure suitable for thinning. On the other hand, for example, a centrifugal fan as described in Patent Document 1 or 2 has an advantage that the static pressure is higher than that of an axial flow fan. It is disadvantageous compared.

  The inventors of the present application, as a centrifugal fan that can be incorporated in a thin electronic device such as a notebook personal computer, has a structure in which an impeller having a small radial dimension and a large axial length rotates at high speed. And applied for a patent for its structure.

  FIG. 4 is an axial sectional view showing the structure of the elongated centrifugal fan according to the previous patent application. FIG. 5 is a cross-sectional view in a direction perpendicular to the axis of a general centrifugal fan housing and impeller. 4 and 5, the shape and scale of each member do not match, but members having the same function are denoted by the same reference numerals. The elongated centrifugal fan shown in FIG. 4 has a substantially cylindrical housing 101 elongated in the axial direction, and an impeller 102 and a motor 103 that rotationally drives the housing are accommodated therein. The impeller 102 is located mainly on the distal end side (right side in FIG. 4) in the housing 101, and the motor 103 is located on the proximal end side (left side in FIG. 4) in the housing 101.

  The impeller 102 includes a wing portion 104 (front end side) in which a plurality of wings 104a elongated in the axial direction are arranged at predetermined intervals along the circumferential direction, and a substantially cylindrical base end portion 105 that supports the wing portion 104. An annular connecting portion 106 that connects and supports the tip portions of the plurality of wings 104 a is provided at the tip portion of the wing portion 104. When the impeller 102 rotates, external air is taken in as shown by an arrow IN from a suction port 107 formed at the front end of the housing 101 in the axial direction. And it sends out from the blower outlet (equivalent to 108 of FIG. 5) formed in a part of the circumferential direction of the housing 101 (as indicated by an arrow OUT in FIG. 5).

  The motor 103 includes a rotating shaft 110, a sleeve 111 that forms a bearing thereof, a sleeve holder 113, a base 114, an armature 115 that is a stator (stator), a magnet 116 that is a rotor (rotor), a rotor yoke 117, and the like. Has been. The base end portion of the rotating shaft 110 abuts on a thrust plate 118 that constitutes a thrust bearing. The distal end portion of the rotating shaft 110 is fitted in the rotor yoke 117, and the proximal end portion 105 of the impeller 102 is fitted on the outer peripheral surface of the distal end side of the rotor yoke 117. A plurality of rotor magnets 116 are disposed in the circumferential direction on the inner peripheral surface of the base end side of the rotor yoke 117. Therefore, the rotor magnet 116, the rotor yoke 117, the rotating shaft 110, and the impeller 102 rotate as a unit.

A stator armature 115 is disposed on the outer periphery of the sleeve holder 113 so as to face the rotor magnet 116 with a certain gap therebetween. When the stator armature 115 is driven (excited) so as to generate a rotating magnetic field, the rotor magnet 116, the rotor yoke 117, the rotating shaft 110, and the impeller 102 rotate integrally according to the rotating magnetic field. Then, as described above, the air taken in from the suction port 107 at the front end in the axial direction of the housing 101 by the rotation of the impeller 102 is sent out from the blowout port formed in a part of the housing 101 in the circumferential direction.
JP 55-32942 A JP-A 61-179394

  With the further thinning of thin electronic devices such as notebook personal computers, there is a demand for further thinning of cooling fans. In order to meet such a demand with the elongated centrifugal fan having the above-described structure, it is necessary to further reduce the radial dimension of the cylindrical outer shape. When the diameter of the impeller is reduced, the air blowing capacity is reduced. However, it is possible to compensate for the reduction in the air blowing capacity by increasing the axial length of the impeller and increasing the rotation speed.

  However, the radial dimension of the motor cannot be easily reduced with the conventional structure. That is, since it is necessary to rotate the impeller at a high speed with a predetermined torque in order to ensure the necessary air blowing capacity, there is a limit to downsizing the stator armature and the rotor magnet. In addition, in order to obtain a stable rotation of the impeller, there is a limit to reducing the radial dimension of the rotating shaft, rotor yoke, sleeve holder, and the like.

  An object of the present invention is to provide an elongated centrifugal fan having a novel structure that enables further reduction of the radial dimension in view of the above-described conventional problems.

  The first configuration of the elongated centrifugal fan according to the present invention (Claim 1) includes an impeller having a blade portion in which a plurality of thin blades are arranged at predetermined intervals along the circumferential direction, and a motor that rotationally drives the impeller. An elongated centrifugal fan arranged in an axial direction, the impeller having a diameter of 25 mm or less, and the radius r of the impeller and the axial length h satisfy a relationship of 2r ≦ h ≦ 20r. Among the members constituting the rotational force generating portion having the armature and the field magnet, and the bearing portion for rotatably holding the rotating member with respect to the fixed member are arranged so as to be aligned in the axial direction. Features.

  By making the shape of the impeller elongated as described above, an elongated centrifugal fan that can be incorporated into a thin device is realized. Moreover, since it is a centrifugal fan, it has a higher static pressure than an axial fan, and is suitable for incorporation into a small electronic device having a high mounting density. Further, since the rotational force generating portion and the bearing portion of the motor are arranged so as to be aligned in the axial direction, it is possible to reduce the outer diameter of the motor. That is, when the rotational force generating part and the bearing part are arranged at substantially the same position in the axial direction, the outer diameter of the motor is the outer diameter of the bearing part plus the radial dimension (thickness) of the rotational force generating part However, when the rotational force generating part and the bearing part are arranged so as to be aligned in the axial direction, the outer diameter of the motor is either the outer diameter of the bearing part or the radial dimension (outer diameter) of the rotational force generating part. It depends on the larger one. Therefore, the outer diameter of the motor can be reduced, and as a result, the radial dimension of the elongated centrifugal fan can be further reduced.

  A second configuration of the elongated centrifugal fan according to the present invention (Claim 2) is characterized in that, in the first configuration, the impeller is rotationally driven at a rotational speed of 10,000 revolutions per minute or more. By performing such high-speed rotation of the impeller, a necessary air volume can be ensured even with a long thin centrifugal fan that has been reduced in size (particularly the radial dimension is reduced).

  The third configuration (Claim 3) of the elongated centrifugal fan according to the present invention is the above first or second configuration, wherein a plurality of integrally rotating members including the impeller and the rotating member are regarded as an integral member. The bearing portion is arranged near the center of gravity. With such a configuration, it is easy to stabilize the rotation of the impeller. That is, the vibration accompanying the rotation of the impeller is reduced and the load on the bearing portion is suppressed, so that the life can be extended. This is particularly useful when the impeller is rotated at a high speed as in the second configuration. When the bearing part is composed of a pair of bearings spaced apart in the axial direction, the configuration in which the bearing part is disposed near the center of gravity is configured such that the intermediate point between both bearings is disposed near the center of gravity. Means a configuration.

  The fourth configuration of the elongated centrifugal fan according to the present invention (Claim 4) is that, in any one of the configurations described above, the outer diameter of the impeller blade portion and the outer diameter of the rotational force generating portion of the motor are substantially the same. Features. According to such a configuration, a limited space can be effectively used when the impeller and the motor are incorporated into the housing or directly into the electronic device.

  The fifth configuration (Claim 5) of the elongated centrifugal fan according to the present invention is characterized in that, in any one of the above configurations, the motor is a DC brushless motor. The direct current brushless motor has the advantages of longer life and quieter operation than the brush motor, and these advantages are the advantages of the elongated centrifugal fan.

  The sixth configuration (Claim 6) of the elongated centrifugal fan according to the present invention is that, in any one of the configurations described above, the bearing portion is configured by a pair of ball bearings that are provided apart in the axial direction. Features. By using a ball bearing, bearing loss is reduced, and an efficient elongated centrifugal fan can be realized.

  According to a seventh configuration (seventh aspect) of the elongated centrifugal fan according to the present invention, in the sixth configuration, the pair of ball bearings are arranged so that the inner ring portions or the outer ring portions are separated from each other in the axial direction or mutually. A preload for urging in the approaching direction is added. The ball bearing eliminates rattling by applying a preload, and more stable rotation is obtained. As a method for applying the preload, a constant pressure preload by urging using an elastic member may be used, or a stationary preload that restricts the axial movement of both the inner ring portion and the outer ring portion with the preload applied.

  According to an eighth configuration (eighth aspect) of the elongated centrifugal fan of the present invention, in any one of the first to fifth configurations, the bearing portion has a rotating shaft fixed to the rotating member and a cylindrical shape loosely fitted thereto. And a sleeve holder having a cylindrical portion fitted on the sleeve and a shaft portion extending from the central portion of the base end side surface to the base portion to form a rotational force generating portion. The stator armature is fixed around the shaft portion of the sleeve holder. According to such a configuration, a configuration in which the outer diameter of the above-described elongated centrifugal fan is further reduced using a slide bearing that is less expensive than a ball bearing, that is, the rotational force generating portion and the bearing portion are aligned in the axial direction. The arranged configuration can be realized.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, when describing the positional relationship and direction of each member vertically and horizontally, it means the positional relationship and direction in the drawings to the last, and it means the positional relationship and direction when incorporated in an actual device. is not.

  FIG. 1 is a sectional view showing the structure of an elongated centrifugal fan according to a first embodiment of the present invention. This elongated centrifugal fan has a substantially cylindrical housing 11 that is elongated in the axial direction, and an impeller 12 and a motor 13 that rotationally drives the housing are accommodated therein. The impeller 12 is located mainly on the distal end side in the axial direction (right side in FIG. 1) in the housing 11, and the motor 13 is located on the proximal end side in the axial direction in the housing 11 (left side in FIG. 1).

  The impeller 12 includes a wing portion 14 (front end side) in which a plurality of wings elongated in the axial direction are arranged at predetermined intervals along the circumferential direction, and a substantially cylindrical base end portion 15 that supports the wing portion 14. An annular connecting portion 16 that connects and supports the tip portions of a plurality of wings is provided at the tip portion of the wing portion. When the impeller 12 rotates, external air is taken in as shown by an arrow IN from a suction port 17 formed at the front end of the housing 11 in the axial direction. And it sends out from the blower outlet (equivalent to 108 of FIG. 5) formed in a part of the circumferential direction of the housing 11 (as indicated by an arrow OUT in FIG. 5).

  The diameter of the impeller 12 elongated in the axial direction is 25 mm or less, and the radius r of the impeller and the axial length h thereof satisfy the relationship of 2r ≦ h ≦ 20r. By making the impeller 12 have such an elongated shape, an elongated centrifugal fan that can be incorporated into a thin device is realized. Moreover, since it is a centrifugal fan, it has a higher static pressure than an axial fan, and is suitable for incorporation into a small electronic device having a high mounting density. The impeller 12 is rotationally driven at a rotational speed of 10,000 revolutions per minute or more, more preferably 15,000 revolutions or more. By performing such high-speed rotation of the impeller 12, it is possible to ensure a necessary air volume even in the case of an elongated centrifugal fan that is miniaturized (particularly, the radial dimension is reduced).

  The motor 13 is arranged such that a rotational force generating portion 13a including a stator armature 21 and a rotor magnet 22 that is a field magnet and a bearing portion 13b that rotatably holds a rotating member (rotor yoke 25) are arranged in the axial direction. Has a structured. With such a structure, the outer diameter of the motor 13, and thus the radial dimension of the elongated centrifugal fan, can be reduced.

  In particular, in this embodiment, the bearing portion 13b is disposed on the distal end side (impeller side) in the axial direction, and the rotational force generating portion 13a is disposed on the proximal end side. That is, the bearing portion 13b is disposed between the impeller 12 and the rotational force generating portion 13a. More specifically, when a plurality of integrally rotating members including the impeller 12 and the rotating member (rotor yoke 25) are regarded as an integral member, the bearing portion 13b is disposed near the center of gravity. Such a configuration makes it easier to stabilize the rotation of the impeller. That is, the vibration accompanying the rotation of the impeller is reduced and the load on the bearing portion is suppressed, so that the life can be extended. In particular, this is useful when the impeller 12 is rotated at a high speed as described above.

  The motor 13 in this embodiment is a direct current brushless motor, and the stator armature 21 of the rotational force generator 13a is disposed on the outer periphery of a fixed shaft 23 that is a fixed member. The metal fixed shaft 23 is press-fitted and fixed in the central through hole of the resin (or metal) base portion 24, and the base portion 24 is fixed to the inner wall on the proximal end side of the resin (or metal) housing 11. The In this way, as shown in FIG. 1, the fixed shaft 23 extends from the proximal end side to the distal end side to about half of the axial length along the central axis of the substantially cylindrical housing 11. The stator armature 21 and the fixed shaft 23 are also fixed by press-fitting as in the case of fixing the base portion 24 and the fixed shaft 23. You may fix with an adhesive agent after press injection.

  The rotor magnet 22 of the rotational force generator 13a is fixed to the inner peripheral surface of a rotor yoke 25 that is a rotating member. That is, a plurality of rotor magnets 22 are arranged at a predetermined pitch in the circumferential direction on the inner peripheral surface of a rotor yoke 25 made of a substantially cylindrical magnetic body, and each rotor magnet 22 and the stator armature 21 have a certain gap. It is comprised so that it may oppose on both sides.

  The substantially cylindrical rotor yoke 25 is long in the axial direction and extends from the rotational force generating portion 13a to the bearing portion 13b. As can be seen from the cross section shown in FIG. 1, the rotor yoke 25 has a stepped portion so that the diameter is slightly reduced from the proximal end side to the distal end side. The rotor magnet 22 is fixed to the inner surface of the large-diameter portion 25a on the proximal end side, and the outer ring portions of a pair of ball bearings 26 constituting the bearing portion 13b are fixed to the inner surface of the small-diameter portion 25b on the distal end side. The pair of ball bearings 26 are disposed so as to be separated from each other in the axial direction, and each outer ring portion is press-fitted and fixed to the inner surface of the small-diameter portion 25 b of the rotor yoke 25. In this case, the adhesive may be further fixed after press-fitting. Further, the base end portion 15 of the impeller 12 is externally fitted and fixed to the outer peripheral surface of the small diameter portion 25b of the rotor yoke 25. Therefore, the rotor yoke 25 and the impeller 12 rotate as a unit.

  FIG. 2 is a partially enlarged sectional view showing a detailed structure of the bearing portion in the first embodiment. A pair of ball bearings 26 (a ball bearing 26P on the base end side and a ball bearing 26D on the front end side) constitute the bearing portion 13b. Each ball bearing 26 (26P and 26D) has a structure in which a plurality of balls 26c are rotatably accommodated between an outer ring portion 26a and an inner ring portion 26b. As described above, the outer ring portion 26 a of each ball bearing 26 is fixed to the inner surface of the small diameter portion 25 b of the rotor yoke 25. On the other hand, the inner ring portion 26 b is loosely fitted with a small clearance so as to be slidable with respect to the fixed shaft 23.

  In the configuration shown in FIG. 2, a stopper ring 27 that restricts movement of the inner ring portion 26 b of the ball bearing 26 </ b> P on the base end side to the axial base end side is attached to the fixed shaft 23. A compression coil spring 29 is interposed between a stopper ring 28 attached to the distal end portion of the fixed shaft 23 and the inner ring portion 26b of the ball bearing 26D on the distal end side. By this compression coil spring 29, the inner ring portion 26b of the ball bearing 26D on the distal end side is urged toward the proximal end side in the axial direction as indicated by an arrow. Further, the outer ring portion 26a of the ball bearings 26D and 26P on the distal end side and the proximal end side is fixed to the rotor yoke 25, and the inner ring portion 26b of the ball bearing 26P on the proximal end side is moved to the axial proximal end side by the stopper ring 27. Therefore, the inner ring portion 26b of the ball bearing 26P on the proximal end side is urged toward the distal end side in the axial direction as indicated by an arrow as a reaction from the stopper ring 27.

  In other words, the inner ring portions 26b of the pair of ball bearings 26 are urged in the axial direction toward each other by the compression coil springs 29 that are urging means. As a result, a preload is applied to each of the pair of ball bearings 26, and stable rotation of the rotor yoke 25, which is a rotating member, and the impeller 12 fixed thereto is obtained.

  As a configuration of the modified example of FIG. 2, a compression coil spring that is a biasing means may be interposed between the inner ring portion 26b of the ball bearing 26P on the proximal end side and the inner ring portion 26b of the ball bearing 26D on the distal end side. . By this compression coil spring 29, the pair of inner ring portions 26b are urged in the direction away from each other in the axial direction. In other words, the inner ring portion 26b of the ball bearing 26P on the base end side is biased toward the base end side in the axial direction, and the inner ring portion 26b of the ball bearing 26D on the tip end side is biased toward the front end side in the axial direction. As a result, a preload is applied to each of the pair of ball bearings 26, and stable rotation of the rotor yoke 25, which is a rotating member, and the impeller 12 fixed thereto is obtained.

  As described above, in the configuration of FIG. 2, the bearing portion 13 b is composed of a pair of ball bearings 26, the outer ring portion 26 a is fixed to the rotating member, the inner ring portion 26 b is loosely fitted to the fixed shaft, and the pair of inner ring portions There is provided a biasing means (compression coil spring) that applies a preload to the pair of ball bearings 26 by biasing 26b in the axial direction and in opposite directions. In the elongated centrifugal fan of the present invention in which the bearing portion 13b is provided not in the rotational force generating portion 13a but in a position shifted in the axial direction, the radial dimension can be sufficiently reduced even if such a structure is adopted. Can do. In any of the configurations, a high-viscosity lubricant such as grease is interposed between the inner ring portion 26b and the fixed shaft 23, so that it is possible to suppress operation noise due to sliding of both.

  As yet another modification of the configuration in which a ball bearing is employed as the bearing portion, a so-called stationary preload may be employed instead of a preload using a biasing means such as the compression coil spring 29 (so-called constant pressure preload). . That is, the pair of inner ring portions 26b is fixed to the fixed shaft 23 by means such as adhesion in a state where the pair of inner ring portions 26b are pressed in the axial direction and in opposite directions to apply a preload to the pair of ball bearings 26. To do. Such a stationary preload is simpler in structure and more advantageous in terms of cost than a constant pressure preload using an urging means such as a compression coil spring 29. However, the durability and stability of the bearing is superior to the constant pressure preload using the biasing means.

  In the elongated centrifugal fan having the above structure, when the stator armature 21 is driven (excited) to generate a rotating magnetic field, the rotor magnet 22, the rotor yoke 25, and the impeller 12 are integrated according to the rotating magnetic field. Rotate to. And the air taken in from the suction inlet 17 of the axial direction front-end | tip part of the housing 11 by rotation of the impeller 12 is sent out from the blower outlet formed in a part of the circumferential direction of the housing 11. FIG.

  FIG. 3 is a sectional view showing the structure of an elongated centrifugal fan according to the second embodiment of the present invention. This elongated centrifugal fan has a substantially cylindrical housing 11 that is elongated in the axial direction, and an impeller 12 and a motor 13 that rotationally drives the housing are accommodated therein. The impeller 12 is located mainly on the front end side in the axial direction (right side in FIG. 3) in the housing 11, and the motor 13 is located on the base end side in the axial direction in the housing 11 (left side in FIG. 3).

  The impeller 12 includes a wing portion 14 (front end side) in which a plurality of wings elongated in the axial direction are arranged at predetermined intervals along the circumferential direction, and a substantially cylindrical base end portion 15 that supports the wing portion 14. An annular connecting portion 16 that connects and supports the tip portions of a plurality of wings is provided at the tip portion of the wing portion. When the impeller 12 rotates, external air is taken in as shown by an arrow IN from a suction port 17 formed at the front end of the housing 11 in the axial direction. And it sends out from the blower outlet formed in a part of the circumferential direction of the housing 11 outside.

  The motor 13 has a structure in which a rotational force generating portion 13a including a stator armature 21 and a rotor magnet 22 and a bearing portion 13b that rotatably holds a rotating member are arranged in an axial direction. In particular, in this embodiment, the bearing portion 13b is disposed on the distal end side (impeller side) in the axial direction, and the rotational force generating portion 13a is disposed on the proximal end side. In the first embodiment, a ball bearing is used as the bearing portion 13b. However, in the second embodiment, a sleeve bearing is used as a slide bearing using an oil-impregnated metal or the like. That is, a sleeve bearing is constituted by a sleeve 31 in which lubricating oil is contained in a cylindrical sintered alloy, a sleeve holder 32 holding the sleeve 31 and the like.

  The sleeve holder 32 is made of metal, and has a cylindrical portion 32a that fits and holds the sleeve 31 and a shaft portion 32b that extends from the center of the base end side end surface to the base end side. The axial center of the cylindrical part 32a and the axial center of the axial part 32b correspond. The shaft portion 32b is press-fitted into the stator armature 21, and the base end portion is press-fitted and fixed in the central through hole of the base portion 24 made of resin (or metal). The base portion 24 is fixed to the inner wall on the base end side of the resin (or metal) housing 11. In this way, the sleeve holder 32 is fixed so that the axial center of the sleeve holder 32 coincides with the central axis of the substantially cylindrical housing 11. The sleeve holder 32 may be further fixed with an adhesive after being press-fitted into the stator armature 21 and the base portion 24.

  A sleeve 31 made of sintered metal containing lubricating oil is fitted into the cylindrical portion 32a of the sleeve holder 32 so that a metal rotation shaft 33 is rotatably inserted into the sleeve 31. The distal end side of the rotating shaft 33 is press-fitted and fixed to the small diameter portion 25c of the rotor yoke 25 that is a rotating member. The substantially cylindrical rotor yoke 25 is long in the axial direction and extends from the rotational force generating portion 13a to the bearing portion 13b. As can be seen from the cross section shown in FIG. 3, the rotor yoke 25 is formed with a stepped portion so that its diameter decreases in three steps from the base end side to the tip end side. That is, the rotor yoke 25 includes a large diameter portion 25a, a medium diameter portion 25b, and a small diameter portion 25c.

  A plurality of rotor magnets 22 are arranged at a predetermined pitch in the circumferential direction on the inner peripheral surface of the large-diameter portion 25a of the rotor yoke 25 so that each rotor magnet 22 and the stator armature 21 face each other with a certain gap therebetween. It is configured. The base end portion 15 of the impeller 12 is fitted on and fixed to the outer peripheral surface of the middle diameter portion 25b of the rotor yoke 25. The rotary shaft 33 is press-fitted and fixed to the small diameter portion 25c of the rotor yoke 25 as described above. Therefore, when the stator armature 21 is driven (excited) to generate a rotating magnetic field, the rotor magnet 22, the rotor yoke 25, the rotating shaft 33, and the impeller 12 rotate integrally according to the rotating magnetic field. And the air taken in from the suction inlet 17 of the axial direction front-end | tip part of the housing 11 by rotation of the impeller 12 is sent out from the blower outlet formed in a part of the circumferential direction of the housing 11. FIG.

  In the cylindrical portion 32a of the sleeve holder 32 constituting the sleeve bearing, a metal thrust plate 34 with which the proximal end portion of the rotating shaft 33 abuts is mounted inside the proximal end surface. This constitutes a thrust bearing. In addition, a seal that closes the annular gap between the opening on the distal end side of the sleeve holder 32 and the rotary shaft 33 is provided, thereby preventing dust from entering the cylindrical portion 32 a of the sleeve holder 32.

  Even in the configuration using the sleeve bearing as the bearing portion as in the second embodiment, by adopting a structure in which the rotational force generating portion 13a and the bearing portion 13b of the present invention are arranged in the axial direction, It becomes possible to further reduce the outer diameter of the elongated centrifugal fan. Further, as shown in FIG. 3, the outer diameter of the cylindrical portion 32 a of the sleeve holder 32 is preferably smaller than the outer diameter of the stator armature 21. According to such a configuration, the motor can be easily assembled while sufficiently securing the size of the stator armature 21 for obtaining the necessary drive torque of the motor 13. The outer diameter of the shaft portion 32 b of the sleeve holder 32 is preferably larger than the outer diameter of the rotating shaft 33. According to such a configuration, the rigidity of the sleeve holder 32 is increased, and the impeller 12 can be stably rotated.

  As mentioned above, although the Example of this invention was described including a modification, this invention is not restricted to these Examples and a modification, It can implement with a various form. Moreover, the material and shape of each member shown in description of the said Example are an example to the last, Comprising: The structure of this invention is not the meaning limited to those materials and shape.

It is sectional drawing which shows the structure of the elongate centrifugal fan which concerns on 1st Example of this invention. It is a partial expanded sectional view which shows the detailed structure of the bearing part in 1st Example. It is sectional drawing which shows the structure of the elongate centrifugal fan which concerns on 2nd Example of this invention. It is sectional drawing of the axial direction which shows the structure of the elongate centrifugal fan which concerns on a previous patent application. It is sectional drawing of the direction perpendicular | vertical to the axis | shaft of the housing and impeller of a general centrifugal fan.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Housing 12 Impeller 13 Motor 13a Rotation force generation part 13b Bearing part 14 Wing | blade part 17 Suction inlet 21 Rotor armature (armature)
22 Rotor magnet (magnetic material)
23 Fixed shaft (fixing member)
24 Base 25 Rotor yoke (rotating member)
26 (26P, 26D) Ball bearing 26a Outer ring portion 26b Inner ring portion 29 Compression coil spring (biasing means)
31 Sleeve 32 Sleeve holder 32a Tubular portion 32b Shaft portion 33 Rotating shaft

Claims (8)

An elongated centrifugal fan in which an impeller having a wing portion in which a plurality of elongated wings are arranged at predetermined intervals along the circumferential direction, and a motor that rotationally drives the impeller are arranged in an axial direction,
The diameter of the impeller is 25 mm or less, the radius r of the impeller and the axial length h thereof satisfy the relationship of 2r ≦ h ≦ 20r, and among the members constituting the motor, an armature and a field magnet are used. An elongated centrifugal fan, characterized in that a rotational force generating portion and a bearing portion that rotatably holds a rotating member with respect to a fixed member are arranged in an axial direction. The elongated centrifugal fan according to claim 1, wherein the impeller is rotationally driven at a rotational speed of 10,000 revolutions per minute or more. 3. The elongate according to claim 1, wherein when the plurality of integrally rotating members including the impeller and the rotating member are regarded as an integral member, the bearing portion is disposed in the vicinity of the center of gravity. Centrifugal fan. 4. The elongated centrifugal fan according to claim 1, wherein an outer diameter of a blade portion of the impeller and an outer diameter of a rotational force generating portion of the motor are substantially the same. 5. The elongated centrifugal fan according to claim 1, wherein the motor is a direct current brushless motor. The elongate centrifugal fan according to any one of claims 1 to 5, wherein the bearing portion includes a pair of ball bearings that are provided apart in the axial direction. The elongated bearing according to claim 6, wherein the pair of ball bearings is provided with a preload that urges the inner ring portions or the outer ring portions in a direction in which they are separated from each other in the axial direction or in a direction in which they are close to each other. Centrifugal fan. The bearing portion is a sliding bearing including a rotating shaft fixed to the rotating member and a cylindrical sleeve loosely fitted thereto, and a cylindrical portion that is externally fitted to the sleeve, and a central portion of a base side surface thereof A sleeve holder having a shaft portion extending from the base to the base portion is provided, and a stator armature constituting the rotational force generating portion is fixed around the shaft portion of the sleeve holder. 6. The elongated centrifugal fan according to any one of 5 above.

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