JP2005264896A - Centrifugal blower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal blower having a lower profile, a longer life and lower cost by eliminating a thrust bearing. <P>SOLUTION: The centrifugal blower 10 comprises an impeller 11 having a plurality of blades 12a, a magnet 17 for receiving a rotating magnetic field to generate rotating force and a rotating shaft 15, a bearing 23, a casing 21 having an iron core 24 for generating the rotating magnetic field, a winding 25 and a rotation driving circuit 26, and a cover 31. For the vertically symmetrical construction of blade portions of the impeller, for example, the upper and lower ends of the plurality of blades 12a are supported by annular blade supporting portions 12b, 12c, respectively, not to cause the thrusting force of the impeller 11 when rotated, and the thrusting position of the impeller is held as predetermined in a balance between magnetic force generated between the magnet 17 and the iron core 24 and the dead weight of the impeller. The thrusting position of the impeller when resting and rotated remains unchanged to achieve a lower profile. The thrust bearing is eliminated to achieve a longer life and lower cost. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a centrifugal blower capable of being thin and small.

  For example, in office electronic equipment, there are some conventional centrifugal blowers mounted for the purpose of cooling electronic components that generate heat, as shown in FIGS. The centrifugal blower 10A includes a blade portion 12 having a plurality of blades 12a and an annular spring support portion 12b that supports the plurality of blades 12a, a hub portion 13, a shaft 15 provided in the hub portion 13, and a hub portion 13. An impeller 11 including a magnet 17 and a magnet case 18 that function as a rotor of an outer rotary motor provided on the inner peripheral surface, an intake port 21a, an exhaust port 21b, a bearing portion 22, and a stator of an outer rotary motor. The iron core 24 and the winding 25 that generate a rotating magnetic field for rotating the magnet 17 and the magnet case 18, the casing 21 that includes the rotation drive circuit 26 that outputs to the winding 25, and the cover 31 that includes the air inlet 31 a. Etc.

  The shaft 15 of the impeller 11 is supported by the bearing portion 22 of the casing 21. Specifically, for example, when a slide bearing is used for the bearing 23, the radial direction of the shaft 15 is supported by the slide bearing, and the thrust direction of the shaft 15 is supported by the thrust receiver 27. In this way, the shaft 15 is supported by the two parts of the bearing 23 and the thrust receiver 27. The thrust receiver 27 is provided in the inner portion of the annular bulging portion 21 c that protrudes on the back surface of the casing 21 together with the holding plate 28.

  Also, as shown in FIG. 9, when a large external force is applied to the impeller 11 in the direction of arrow C due to impact or vibration, the movement amount of the impeller 11 in the direction of arrow C is regulated, and the impeller 11 is covered, for example, In order to prevent damage to the blade 12a and other parts such as the cover 31 due to contact with other parts such as 31 or the generation of noise, the shaft 15 is prevented from coming off at an appropriate interval from the bearing 23 or the casing 21. A washer 16 is provided.

  Here, if a predetermined energization is applied to the rotation drive circuit 26, the impeller 11 rotates about the shaft 15, sucks air from both the intake ports 21a and 31a, passes through the scroll portion, and blows air to the exhaust port 21b. It becomes.

10 and 11 show an axial blower having a bearing structure in which the thrust receiver 27 is omitted. In the axial blower 100, the position in the thrust direction when the impeller 111 is stopped is constant due to the balance between the magnetic force generated between the magnet 117 driving the impeller 111 and the iron core 124 and the own weight of the impeller 111. (See, for example, Patent Document 1).
No. 7-1528.

The conventional centrifugal blower includes a thrust receiver for supporting the thrust direction of the metal shaft. The provision of this thrust receiver has mainly caused the following problems.
1) Since a space for arranging the thrust receiver is required in the thrust direction, it is an obstacle to making the centrifugal blower thinner and smaller.
2) As a material of the thrust receiver on which the shaft slides, a resin having a low frictional resistance is generally used, and the thrust receiver is gradually worn by sliding with the metal shaft. Therefore, the lifetime of the centrifugal fan is determined by the wear of the thrust receiver.
3) Sliding between the shaft and the thrust receiver was one of the sources of vibration and noise.
4) In order to reduce the frictional resistance when the shaft and the thrust receiver slide, the tip of the shaft that slides with the thrust receiver is generally polished on a spherical surface, and the shaft is expensive. It was.

  The present invention has been made to solve such problems, and by supporting the thrust direction of the shaft other than the thrust receiver, it eliminates the thrust receiver, and is thin, small, long life, low noise, low vibration, It aims at providing the centrifugal blower which can implement | achieve low cost.

  The present invention relates to an impeller having a plurality of blades, a magnet that generates a rotational force by receiving a rotating magnetic field, a magnet case, and a shaft that serves as a rotation center, and an intake air that houses the impeller and serves as an outside air intake port. A cover provided with a bearing supporting the radial direction of the opening and the shaft, a casing provided with the iron core and windings for generating the rotating magnetic field and a rotation drive circuit, and an intake port which is an intake port for outside air In the centrifugal blower having the structure, the impeller is configured so that no thrust force is generated when rotating, and the thrust wheel position is determined by the magnetic force generated between the magnet and the iron core and the weight of the impeller. It is held at a fixed position by the balance.

  And when a large external force is applied to the impeller due to impact or vibration, the movement amount of the impeller in the thrust direction is restricted, and the blade or other part is damaged due to contact with the other part of the impeller, It is preferable to provide a retaining mechanism for preventing the generation of noise. The bearing is preferably a slide bearing or a dynamic pressure bearing.

According to the present invention, the impeller is configured such that no thrust force is generated when the impeller rotates, and the impeller thrust direction position is determined by the magnetic force generated between the magnet and the iron core and the impeller's own weight. Therefore, the following effects can be obtained.
1) Since the position of the impeller in the thrust direction is not changed when the impeller is stationary, when it is rotating, and when the rotational speed is changed, the thrust receiver can be eliminated. Therefore, a space in the thrust direction for arranging the thrust receiver is not necessary. Further, since the position of the impeller in the thrust direction at the time of stationary and rotation does not change, the centrifugal blower can be made thinner and smaller.
2) Since the thrust receiver is not worn, the life of the centrifugal fan can be extended.
3) Since there is no sliding between the shaft and the thrust receiver, the centrifugal blower can be reduced in vibration and noise.
4) Since there is no thrust receiver itself, spherical processing of the shaft tip of the impeller is unnecessary. Further, since the structure is simplified, the assembly time can be shortened and the cost of the centrifugal fan can be reduced. As a result, for example, in an office electronic device, a centrifugal blower suitable for a cooling device mounted for the purpose of cooling electronic components that generate heat can be provided.

Embodiment 1
1 and 2 show the cross-sectional structure and appearance of a centrifugal blower according to an embodiment of the present invention, and FIG. The centrifugal blower 10 includes an impeller 11, a casing 21 having an intake port 21a and an exhaust port 21b that are intake ports for outside air, and a cover 31 having an intake port 31a that is an intake port for outside air.

  The impeller 11 includes a plurality of blades 12a, a blade portion 12 including annular blade support portions 12b and 12c that respectively support upper and lower ends of the plurality of blades 12a, a hub portion 13, and a hub portion 13 and an annular shape. A plurality of ring stoppers 14 for connecting the blade support portions 12 b, an impeller shaft 15 provided at the center of the hub portion 13, a retaining washer 16 attached to the tip of the shaft 15, and a hub portion 13 The magnet 17 and the magnet case 18 function as a rotor of an outer rotary motor provided inside the motor. In addition, the blade | wing part 12, the hub part 13, and the ring stopper part 14 are integrally formed with resin. Further, a retaining protrusion 13 a is formed on the lower surface side of the center portion of the hub portion 13.

  The casing 21 has a cylindrical bearing portion 22 that protrudes inward and upward at the center, a bearing 23 is provided inside the bearing portion 22, and functions as a stator of the outer rotary motor on the outside to function as the impeller 11. An iron core 24 and a winding 25 for generating a rotating magnetic field for rotating the magnet 17 and the magnet case 18 are provided. In addition, a rotation drive unit 26 that outputs to the winding 25 is provided on the inner surface of the casing 21 that faces the hub portion of the impeller.

  Further, the cylindrical bearing portion 22 is formed such that the inner diameter and outer diameter of the lower portion are slightly larger than the upper portion, and a step portion 22a formed slightly below the bearing 23 is provided on the shaft 16 of the impeller. It faces the stop washer 17 with a predetermined gap g1. Further, the step portion 22 b formed outside the bearing portion 22 is a lower end positioning portion of the iron core 24. The upper end surface 22c of the bearing portion 22 faces the lower surface of the retaining projection 13a of the impeller 11 with a predetermined gap g2.

  The centrifugal blower 10 is not provided with a thrust receiver (27 in FIG. 8) that supports the thrust direction of the shaft 15, the radial direction of the shaft 15 is supported by the bearing 23, and the shaft 15 and thus the impeller 11 in the thrust direction. The position is held at a fixed position where the magnetic force generated between the magnet 17 and the iron core 24 and the weight of the impeller 11 are balanced. The position of the impeller 11 in the thrust direction is determined by the positional relationship and dimensions of the magnet 17 and the iron core 24 or the magnitude of the magnetic force of the magnet 17. Therefore, the thrust direction position of the impeller 11 when the impeller rotation is stopped seems to be held at a constant thrust direction position by the balance between the magnetic force generated between the magnet 17 and the iron core 24 and the own weight of the impeller 11. It is. In addition, a plurality of blades 12a are supported by annular blade support portions 12b and 12c of the same size so that the flow of air flowing through the blades 12a is vertically symmetric, so that the blade portions 12 have a vertically symmetric structure. The torque in the thrust direction is made small. By the way, as a result of numerical analysis of the thrust force of the centrifugal blower of both sides suction and the axial flow blower having the same blowing performance (typical blowing performance of the cooling fan of the CPU of the notebook PC), about 0.04 gf in the centrifugal blower, It was about 4 gf in the axial blower.

  Therefore, unless the external force in the thrust direction is applied to the centrifugal blower 10, the impeller 11 hardly moves in the thrust direction. Accordingly, the gap g1 between the retaining washer 17 and the step 22b of the bearing 22 and the gap g2 between the upper end surface 22c of the bearing 22 and the retaining projection 13a of the impeller 11 are reduced, and the casing 21 and the cover The gap between 23 is made smaller than that of the conventional centrifugal blower. Further, since a thrust receiver is not required, the bulging portion (21c in FIG. 8) on the lower surface of the conventional casing is eliminated.

  Next, the operation of the centrifugal blower 10 will be described. The centrifugal blower 10 is maintained in a thrust direction position by a balance between the magnetic force generated between the magnet 17 and the iron core 24 and the weight of the impeller 11 in a stopped state. When a predetermined energization is applied to the rotation drive circuit 26 of the centrifugal blower 10, the impeller 11 rotates and is sucked from both the intake ports 21a and 31a as shown in FIG. 1, and is blown from the exhaust port 21b through the scroll portion. . Since the blade portion 12 including the plurality of blades 12a and the annular blade support portions 12b and 112c has a vertically symmetric structure, the flow of air flowing through the blade portion 12 is vertically symmetric, and the impeller 11 has torque in the thrust direction. It hardly occurs. Therefore, the impeller 11 rotates at the same position as the position in the thrust direction when in a stopped state, and hardly moves in the thrust direction even if the rotation speed changes. Therefore, it is possible to reduce the thickness of the centrifugal blower 10 by reducing the gaps g1 and g2.

  The centrifugal blower 10 is provided with the annular blade support portion 14c on the plurality of blades 12 so that the flow of air flowing through the blade 12a portion is vertically symmetric, but is not limited thereto. . For example, as shown in FIG. 5, the flow of the air flowing through the blades 12a can be made closer to the vertical symmetry by providing the annular blade support portion 14a so as to be at the center of the plurality of blades 12a.

  With respect to the centrifugal fan 10, the conventional axial fan 100 (FIGS. 10 and 11) has a position in the thrust direction when the impeller 111 is stationary, the positional relationship and dimensions of the magnet 117 and the iron core 124, or the magnetic force of the magnet 117. However, unlike the centrifugal blower 10 of the present invention, air flows in the thrust direction when the impeller 111 rotates, and as a reaction force, the impeller 111 has a thrust in the direction of arrow D (thrust thrust). D) occurs. Therefore, the position of the impeller 111 in the thrust direction during rotation is determined by the balance between the magnetic force generated between the magnet 117 and the iron core 124, the weight of the impeller 111, and the thrust D in the thrust direction. Further, the thrust D in the thrust direction varies depending on the rotational speed of the impeller 111. Accordingly, setting the positional relationship and dimensions of the magnet 117 and the iron core 124 or the magnitude of the magnetic force of the magnet 117 so that the position in the thrust direction during rotation of the impeller 111 becomes a predetermined position is described above. It is difficult compared with the centrifugal blower 10.

  Next, how to prevent the impeller 11 of the centrifugal blower 10 from coming off will be described. When an external force is applied in the direction of arrow A as shown in FIG. 4A, a stepped portion 22 a in which a retaining washer 16 provided on the shaft 15 at an appropriate distance from the casing 21 is formed inside the bearing portion 22. At this time, since the amount of movement of the impeller 11 in the thrust direction is restricted, it is possible to prevent damage to the blade portion 12 and other parts due to contact with the other parts of the impeller 11 or generation of noise.

  When an external force is applied in the direction of arrow B as shown in FIG. 4B, the retaining projection 13a provided on the impeller 11 hits the tip surface 22c of the iron core mounting portion 22 and the arrow B of the impeller 11 Since the amount of movement in the direction is restricted, it is possible to prevent the blade 12 and other parts from being damaged and noise generated due to contact with the other parts of the impeller 11.

  At this time, as shown in FIG. 9, when the retaining washer 17 or the retaining projection 13 a comes into contact with the bearing 23 and stops, the retaining washer 17 or the retaining projection 13 a removes the bearing oil of the bearing 23, There is a possibility that the bearing 23 is seized due to insufficient bearing oil. Therefore, it is desirable to set the dimensions and shapes of the retaining washer 17, the retaining projection 13b, the bearing 23, and the bearing portion 22 so that they stop at a portion on the casing 21 side other than the bearing 23 as shown in FIG.

The longitudinal cross-sectional view which shows the structure of a centrifugal blower (embodiment). (A) And (B) is a perspective view which shows the external appearance of the upper surface side and lower surface side of a centrifugal blower (embodiment). The longitudinal cross-sectional view which expands and shows the principal part of a centrifugal blower (embodiment). Explanatory drawing of the function to prevent the centrifugal blower from coming off (embodiment). The longitudinal cross-sectional view which shows the structure of a centrifugal blower (modification). The longitudinal cross-sectional view which shows the structure of a centrifugal blower (conventional example). (A) And (B) is a perspective view which shows the external appearance of the upper surface side and lower surface side of a centrifugal blower (conventional example). The principal part expansion longitudinal cross-sectional view of a centrifugal blower (conventional example). Explanatory drawing of the function to prevent the centrifugal blower from coming off (conventional example). Structural explanatory drawing of an axial blower (conventional example). The perspective view which shows the external appearance of an axial blower (conventional example).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 10A ... Centrifugal blower, 11 ... Impeller, 12 ... Blade part, 12a ... Blade, 12b, 12c ... Blade support part, 13 ... Hub part, 13a ... Retaining protrusion, 15 ... Shaft, 16 Retaining washer 17 DESCRIPTION OF SYMBOLS ... Magnet, 18 ... Magnet case, 21 ... Casing, 22 ... Bearing part, 23 ... Bearing 23 ... Iron core, 25 ... Winding, 26 ... Drive circuit, 27 ... Thrust receiver, 31 ... Cover, 100 ... Centrifugal blower, 111 ... impeller, 112 ... vane, 113 ... hub, 115 ... shaft, 116 ... retaining washer, 117 ... magnet, 118 ... magnet case, 121 ... casing, 122 ... bearing, 114 ... iron core, 115 ... winding 116: Driving circuit.

Claims (4)

An impeller having a plurality of blades and a magnet that generates a rotational force by receiving a rotating magnetic field, a magnet case, and a shaft serving as a rotation center; an intake port that stores the impeller and is an intake port for outside air; and the shaft A centrifugal bearing having a bearing that supports the radial direction of the motor, a casing that includes the iron core and windings for generating the rotating magnetic field, and a rotation drive circuit, and a cover that is provided with an intake port that is an intake port for outside air. In the blower,
The impeller is configured so that no thrust force is generated when the impeller rotates, and the position of the impeller in the thrust direction depends on the balance between the magnetic force generated between the magnet and the iron core and the weight of the impeller. A centrifugal blower characterized by being held at a fixed position. When a large external force is applied to the impeller in the thrust direction due to impact or vibration, the movement amount of the impeller in the thrust direction is restricted, and the blade or other parts are damaged due to contact with other parts of the impeller or noise The centrifugal blower according to claim 1, further comprising a retaining mechanism for preventing occurrence and the like. The centrifugal blower according to claim 1, wherein the bearing is a sliding bearing. The centrifugal blower according to claim 1, wherein the bearing is a dynamic pressure bearing.

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