Blower fan

Abstract

To provide a blower fan capable of suppressing generation of abnormal noise caused by vibration of an impeller.SOLUTION: Since the covering member formed of an elastic material is interposed between the inner periphery of the insertion hole of the impeller and the outer periphery of the shaft (tapered portion) in a state where the impeller is attached to the shaft of the motor, vibration transmitted from the shaft to the impeller can be suppressed. Further, since the tapered portion and the covering member are reduced in diameter toward the distal end side of the shaft, when the shaft is passed through the insertion hole of the impeller from the distal end side, the tapered portion and the covering member come into contact with each other at a point where the inner diameter of the insertion hole and the outer diameter of the covering member coincide with each other. Therefore, a gap due to manufacturing variations is less likely to occur between the inner periphery of the insertion hole and the outer periphery of the covering member that covers the shaft, and the impeller can be stabilized with respect to the shaft, so that vibration of the impeller can be suppressed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a blower fan that blows air by rotating an impeller attached to a shaft of a motor. [Background technology]

[0002] A blower fan, which rotates an impeller driven by a motor to send air, is connected to a combustion device such as a water heater and used to send air for combustion. The impeller has a through-hole at the center of a rotating disk that supports multiple blades, through which the motor shaft passes. The impeller is typically attached by inserting the shaft into the through-hole with two washers sandwiching both sides of the rotating disk, and then tightening a nut from the tip of the shaft to hold the rotating disk between the base of the shaft and the nut.

[0003] In such blower fans, when the impeller is rotated by the motor, an abnormal noise can occur. This abnormal noise is mainly caused by the vibration of the motor being transmitted to the impeller, which can resonate in the combustion device to which the blower fan is connected, resulting in a loud noise. Therefore, it has been proposed to suppress the transmission of vibration to the impeller by inserting a damping member that attenuates the vibration between the rotating disk and the washer (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-23750 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a blower fan in which a damping member is interposed between the rotating disk and the washer as described above, although it is possible to suppress vibrations transmitted from the base of the shaft or the nut to the rotating disk via the washer, there is still a problem in that the inner periphery of the insertion hole in the rotating disk may come into direct contact with the outer periphery of the shaft, causing abnormal noise due to vibrations being transmitted from the shaft to the impeller.

[0006] An object of the present invention is to provide a blower fan that can suppress the generation of abnormal noise caused by vibration of the impeller. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the blower fan of the present invention employs the following configuration: <First aspect> In a blower fan that blows air by rotating an impeller attached to the shaft of a motor, The impeller is provided with an insertion hole through which the shaft is inserted, The shaft has a tapered portion whose outer diameter decreases toward the tip end, a covering member formed of an elastic material in a cylindrical shape, the diameter of which decreases toward the tip side of the shaft and which is substantially parallel to the outer circumferential surface of the tapered portion, capable of covering at least a part of the outer circumferential surface of the tapered portion; The impeller has an inner diameter of the insertion hole that is smaller than the maximum outer diameter of the tapered portion, and when attached to the shaft, the inner periphery of the insertion hole is in contact with the outer periphery of the covering member. It is characterized by:

[0008] In the blower fan of the first aspect, when the impeller is attached to the motor shaft, a covering member made of an elastic material is interposed between the inner periphery of the impeller insertion hole and the outer periphery of the shaft (tapered portion), thereby suppressing vibration transmitted from the shaft to the impeller. Furthermore, because the tapered portion and covering member have diameters that decrease toward the tip of the shaft, when the shaft is inserted into the impeller insertion hole from the tip, the inner diameter of the insertion hole and the outer diameter of the covering member come into contact with each other at the same point. Therefore, compared to when the shaft does not have a tapered portion (when the portion inserted into the insertion hole is straight), a gap due to manufacturing variations is less likely to occur between the inner periphery of the insertion hole and the outer periphery of the covering member that covers the shaft. This stabilizes the impeller relative to the shaft and makes it possible to suppress impeller vibration.

[0009] <Second aspect> In the blower fan of the first aspect, The inner peripheral surface of the insertion hole is formed substantially parallel to the outer peripheral surface of the tapered portion. It is characterized by:

[0010] In the second aspect of the blower fan, the inner surface of the insertion hole and the outer surface of the covering member attached to the tapered section are in surface contact, which allows the impeller to sit better on the shaft than if the inner surface of the insertion hole had a uniform diameter with no change in inner diameter, thereby improving stability.

[0011] <Third aspect> In the blower fan of the second aspect, the impeller has a cylindrical protruding portion at the center of a rotating disk that supports a plurality of blades, the protruding portion being generally parallel to an outer circumferential surface of the tapered portion and having a diameter that decreases toward a tip end of the shaft, The inside of the protrusion serves as the insertion hole. It is characterized by:

[0012] In the third aspect of the blower fan, by providing a protrusion in the center of the rotating disk, it becomes easier to ensure a contact area between the inner surface of the insertion hole and the outer surface of the covering member attached to the tapered portion, even without making the rotating disk thicker, making it possible to further stabilize the impeller (rotating disk) relative to the shaft.

[0013] <Fourth aspect> In the blower fan according to any one of the first to third aspects, The shaft has a male threaded portion formed on a tip side of the tapered portion, the male threaded portion being adapted to thread with the female thread of the nut, a cylindrical portion having an inner diameter larger than that of the insertion hole is provided concentrically with the female screw on a surface of the nut facing the impeller, An elastic body is provided between the end face of the cylindrical portion and the impeller. It is characterized by:

[0014] In the blower fan of the fourth aspect, when the nut is fastened to the male threaded portion of the shaft, the end face of the cylindrical portion comes into contact with the impeller via the elastic body before the female thread of the nut reaches the end of the male threaded portion on the tapered portion side. This makes it possible to press the impeller with the nut and fix it to the shaft even if the insertion hole for the impeller is located on the larger diameter side than the smaller diameter end of the tapered portion. Furthermore, because the elastic body is interposed between the end face of the cylindrical portion and the impeller, vibration transmitted from the shaft to the impeller via the nut can be suppressed.

[0015] <Fifth aspect> In the blower fan of the second or third aspect, The shaft has a male threaded portion formed on a tip side of the tapered portion, the male threaded portion being adapted to thread with the female thread of the nut, a minimum outer diameter of the tapered portion is larger than an outer diameter of the male thread portion, and a minimum inner diameter of the insertion hole is larger than the outer diameter of the male thread portion and smaller than the minimum outer diameter of the tapered portion, An elastic body is provided between the nut and an end face of the insertion hole on the small diameter side of the impeller. It is characterized by:

[0016] In the fifth aspect of the blower fan, the shaft is inserted through the impeller's insertion hole from the tip end. When the inner circumferential surface of the insertion hole contacts the outer circumferential surface of the covering member attached to the tapered portion, positioning the impeller relative to the shaft, the narrow-diameter end of the insertion hole does not contact the outer circumferential surface of the covering member but protrudes toward the male threaded portion. Therefore, even when a typical nut is used, the narrow-diameter end face of the insertion hole in the impeller can be pressed before the female threads of the nut reach the end of the male threaded portion on the tapered portion side, thereby securing the impeller to the shaft. Furthermore, an elastic body is interposed between the narrow-diameter end face of the insertion hole in the impeller and the nut, thereby suppressing vibrations transmitted from the shaft to the impeller via the nut. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is an exploded view showing the general structure of a blower fan 1 according to the present embodiment. [Figure 2] 2 is an enlarged perspective view showing a configuration in which the impeller 10 of the blower fan 1 of the present embodiment is attached to the shaft 31 of the motor 30. FIG. [Figure 3] 10 is an explanatory diagram showing an enlarged view of how the impeller 10 is fixed to the shaft 31 using a nut 43. FIG. [Figure 4] 10 is an explanatory diagram showing an enlarged view of a configuration for attaching the impeller 10 to the shaft 31 of the motor 30 in the blower fan 1 of the first modified example. FIG. [Figure 5] 10 is an explanatory diagram showing an enlarged view of a configuration for attaching the impeller 10 to the shaft 31 of the motor 30 in the blower fan 1 of the second modified example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1 is an exploded view showing the general structure of a blower fan 1 according to this embodiment. As shown in the figure, the blower fan 1 according to this embodiment includes an impeller 10 that generates air by rotating, a fan case 20 that houses the impeller 10, a motor 30 that rotates the impeller 10, and a fixing plate 35 for fixing the motor 30 to the fan case 20.

[0019] The impeller 10 is a so-called sirocco fan and includes a substantially circular rotating disk 11, a plurality of blade plates 12 each having one end attached to the outer periphery of the rotating disk 11, and an annular connecting plate 13 connecting the other ends of the plurality of blade plates 12. The rotating disk 11 is formed with an insertion hole 14 at the position of the rotation center of the impeller 10, and a shaft 31 of a motor 30 is inserted through the insertion hole 14 as described below. Note that although the impeller 10 in this embodiment will be described as a sirocco fan, it may be another type of impeller, such as a propeller fan.

[0020] The fan case 20 is formed by combining sheet metal members and has a circular opening 21 that is larger than the outer diameter of the impeller 10, an inlet 22 formed in a bell-mouth shape through which air flows into the fan case 20, and an outlet 23 through which air flows out of the fan case 20.

[0021] Motor 30 is a three-phase AC motor with a roughly cylindrical exterior shape, with shaft 31 protruding from the center of one end face of the cylindrical shape and a male thread formed on the tip side of shaft 31. In addition, mounting portions 32 for mounting motor 30 to fixed plate 35 protrude radially outward from three locations on the outer periphery of the end face on the side from which shaft 31 protrudes.

[0022] The fixing plate 35 is a circular plate-like member, and its outer diameter is set to be larger than the diameter of the opening 21 formed in the fan case 20. Three screw holes 35a are formed on the inner edge of the fixing plate 35 for screwing the mounting portion 32 of the motor 30. Furthermore, three screw holes 35b are formed on the outer edge of the fixing plate 35 for screwing the fixing plate 35 to the fan case 20.

[0023] When assembling the blower fan 1, first, the mounting portion 32 of the motor 30 is screwed into the threaded hole 35a of the fixing plate 35 using a mounting screw (not shown). Then, the impeller 10 is attached to the shaft 31 of the motor 30 by inserting the shaft 31 of the motor 30 into the insertion hole 14 of the rotating disk 11 and tightening a nut 43 onto the male thread formed on the tip side of the shaft 31. After the impeller 10, fixing plate 35, and motor 30 are assembled together in this manner, the impeller 10 is inserted into the fan case 20 through the opening 21 formed in the fan case 20, and the fixing plate 35 is fixed to the fan case 20 using the threaded hole 35b of the fixing plate 35 and a mounting screw (not shown).

[0024] In the blower fan 1 assembled in this manner, when the impeller 10 is rotated by the drive of the motor 30, centrifugal force generates a flow of air that blows out from the inside of the impeller 10 to the outside, and the blown air travels along the outer periphery of the fan case 20 and is sent into the housing of a water heater or the like connected to the outlet 23. In addition, as the air blows out of the impeller 10, negative pressure is created inside the impeller 10, and air from outside the fan case is sucked into the inside of the impeller 10 through the inlet 22.

[0025] In such a blower fan 1, abnormal noise may be generated as the impeller 10 rotates due to the driving of the motor 30. This abnormal noise is mainly generated when vibrations of the motor 30 are transmitted to the impeller 10, and may resonate in the housing to which the blower fan 1 is connected, resulting in a loud noise. Therefore, in the blower fan 1 of this embodiment, in order to suppress the generation of abnormal noise due to vibrations of the impeller 10, the impeller 10 is attached to the shaft 31 of the motor 30 in the following manner.

[0026] Fig. 2 is an enlarged perspective view showing the structure for attaching the impeller 10 to the shaft 31 of the motor 30 in the blower fan 1 of this embodiment. Fig. 2 shows the state before the impeller 10 is attached to the shaft 31 of the motor 30. The motor 30 has already been attached to the fixing plate 35.

[0027] As shown in the figure, a truncated cone-shaped tapered section 31a whose outer diameter gradually decreases toward the tip side is formed on the base end side (the body side of the motor 30) of the shaft 31 of the motor 30, and a male threaded section 31b having a male thread that screws into the female thread of a nut 43, as will be described later, is provided on the tip side of the tapered section 31a on the shaft 31. In addition, a vibration-proof member 41 is attached to the tapered section 31a, covering the outer circumferential surface.

[0028] The vibration-damping member 41 is made of an elastic material such as rubber, has a thickness sufficient to reduce vibrations transmitted from the shaft 31, and has a shape that is roughly similar to the outer circumferential surface of the tapered portion 31a (a truncated cone shape that tapers toward the tip of the shaft 31). This allows the inner circumferential surface of the vibration-damping member 41 to be in close contact with the outer circumferential surface of the tapered portion 31a when the vibration-damping member 41 is attached to the tapered portion 31a. The vibration-damping member 41 corresponds to the "covering member" of this invention.

[0029] In the impeller 10, the inner diameter D1 of the insertion hole 14 formed in the rotating disk 11 is larger than the minimum outer diameter D2 of the tapered portion 31a of the shaft 31 and smaller than the maximum outer diameter D3 of the tapered portion 31a. Note that the minimum outer diameter of the vibration-damping member 41 is larger than the minimum outer diameter D2 of the tapered portion 31a due to the thickness of the vibration-damping member 41, but is smaller than the inner diameter D1 of the insertion hole 14. In addition, the maximum outer diameter of the male thread portion 31b is equal to or smaller than the minimum outer diameter D2 of the tapered portion 31a.

[0030] For this reason, when the shaft 31 with the vibration-damping member 41 attached to the tapered portion 31a is passed through the insertion hole 14 of the rotating disk 11, the inner periphery of the insertion hole 14 comes into contact with the outer periphery of the vibration-damping member 41 when the inner diameter D1 of the insertion hole 14 and the outer diameter of the vibration-damping member 41 coincide with each other, thereby positioning the rotating disk 11 relative to the shaft 31. Thereafter, the nut 43 is tightened onto the male thread portion 31b of the shaft 31, thereby fixing the impeller 10 to the shaft 31.

[0031] FIG. 3 is an explanatory enlarged view showing how the impeller 10 is fixed to the shaft 31 using the nut 43. FIG. 3 shows a cross section cut along a plane including the center of rotation of the shaft 31. First, FIG. 3(a) shows a state before the nut 43 is fastened to the male thread portion 31b of the shaft 31. As described above, the impeller 10 is positioned relative to the shaft 31 by the inner periphery of the insertion hole 14 of the impeller 10 contacting the outer periphery of the vibration-damping member 41 covering the tapered portion 31a of the shaft 31. In this state, the rotating disk 11 is positioned closer to the larger diameter side than the smaller diameter side end of the tapered portion 31a of the shaft 31, and therefore there is a gap between the rotating disk 11 and the end of the male thread portion 31b on the tapered portion 31a side.

[0032] As shown in the figure, the nut 43 of this embodiment has a female threaded portion 43a that screws onto the male threaded portion 31b of the shaft 31, and a cylindrical portion 43b that is formed concentrically with the female threaded portion 43a from the outer edge of the surface that faces the rotating disk 11. The inner diameter of this cylindrical portion 43b is larger than the inner diameter of the insertion hole 14 of the rotating disk 11. A flange portion 43c is formed at the end of the cylindrical portion 43b that faces the rotating disk 11, widening radially outward. An anti-vibration washer 42 made of an elastic material such as rubber and formed in an annular shape substantially the same as the flange portion 43c is interposed between the flange portion 43c and the rotating disk 11.

[0033] 3(b), when such a nut 43 is fastened to the male thread portion 31b of the shaft 31, the flange portion 43c comes into contact with the rotating disk 11 via the vibration-isolating washer 42 before the female thread portion 43a of the nut 43 reaches the end of the male thread portion 31b of the shaft 31 on the tapered portion 31a side. Therefore, even if there is a gap between the end of the male thread portion 31b on the tapered portion 31a side and the rotating disk 11, the nut 43 can press the rotating disk 11, thereby fixing the impeller 10 to the shaft 31.

[0034] The range over which the vibration-damping member 41 covers the tapered portion 31a of the shaft 31 does not need to be the entire outer peripheral surface of the tapered portion 31a, but only needs to cover an area that includes the vicinity of the point at which the outer diameter of the vibration-damping member 41 and the inner diameter of the insertion hole 14 coincide in design. The cylindrical portion 43b of the nut 43 may be formed by providing a deep countersunk hole concentric with the female thread portion 43a on the rotating disk 11 side of a known nut, or by fastening a separately manufactured cylindrical member to the end face of the known nut on the rotating disk 11 side.

[0035] As described above, the shaft 31 of the motor 30 in the blower fan 1 of this embodiment is provided with a tapered portion 31a whose outer diameter decreases toward the tip, and the vibration-damping member 41 is attached to cover the outer circumferential surface of the tapered portion 31a. The inner diameter of the insertion hole 14 of the impeller 10 is smaller than the maximum outer diameter of the tapered portion 31a, and the inner periphery of the insertion hole 14 is in contact with the outer periphery of the vibration-damping member 41 when the impeller 10 is attached to the shaft 31.

[0036] In the blower fan 1 of this embodiment, when the impeller 10 is attached to the shaft 31 of the motor 30, the vibration-damping member 41 is interposed between the inner periphery of the insertion hole 14 of the impeller 10 and the outer periphery of the shaft 31 (tapered portion 31a), thereby suppressing vibrations transmitted from the shaft 31 to the impeller 10. Furthermore, because the tapered portion 31a and the vibration-damping member 41 have diameters that decrease toward the tip of the shaft, when the shaft 31 is inserted into the insertion hole 14 of the impeller 10 from the tip side, the inner diameter of the insertion hole 14 and the outer diameter of the vibration-damping member 41 come into contact with each other at the same location. Therefore, compared to when the shaft 31 does not have the tapered portion 31a (the portion inserted into the insertion hole 14 is straight), a gap due to manufacturing variations is less likely to occur between the inner periphery of the insertion hole 14 and the outer periphery of the vibration-damping member 41 covering the shaft 31. This stabilizes the impeller 10 relative to the shaft 31 and makes it possible to suppress vibrations of the impeller 10.

[0037] Furthermore, if the shaft 31 does not have the tapered portion 31a (the portion that is inserted into the insertion hole 14 is straight), it is necessary to interpose an elastic body such as a rubber washer between the impeller 10 (rotating disc 11) and the base end of the shaft 31 in order to suppress vibrations that are transmitted from the base end of the shaft 31 (the body side of the motor 30) to the impeller 10. In contrast, in the blower fan 1 of this embodiment, the vibration-proof member 41 is not only interposed between the inner periphery of the insertion hole 14 of the impeller 10 and the outer periphery of the shaft 31, but is also interposed between the impeller 10 and the base end of the shaft 31. Therefore, even if an elastic body is omitted, it is possible to suppress vibrations that are transmitted from the base end of the shaft 31 to the impeller 10.

[0038] In the blower fan 1 of this embodiment, a cylindrical portion 43b is provided concentrically with the female thread portion 43a on the surface of the nut 43 facing the impeller 10 (rotating disk 11), and the inner diameter of the cylindrical portion 43b is larger than the inner diameter of the insertion hole 14 of the rotating disk 11. A flange portion 43c is formed radially outward from the end of the cylindrical portion 43b facing the rotating disk 11, and a vibration-isolating washer 42 is interposed between the flange portion 43c and the rotating disk 11. In this manner, when the nut 43 is fastened to the male thread portion 31b of the shaft 31, the flange portion 43c (the end face of the cylindrical portion 43b) comes into contact with the rotating disk 11 via the vibration-isolating washer 42 before the female thread portion 43a of the nut 43 reaches the end of the male thread portion 31b facing the tapered portion 31a. As a result, even if the insertion hole 14 of the rotating disk 11 is located on the larger diameter side than the smaller diameter end of the tapered portion 31a, the flange portion 43c of the nut 43 can press the rotating disk 11 and fix it to the shaft 31. Furthermore, since the vibration-isolating washer 42 is interposed between the flange portion 43c and the rotating disk 11, vibrations transmitted from the shaft 31 to the impeller 10 via the nut 43 can be suppressed.

[0039] The following variations of the blower fan 1 of the above-described embodiment are also available. The following describes the variations, focusing on the differences from the above-described embodiment. In the description of the variations, the same components as those in the above-described embodiment are given the same reference numerals and will not be described again.

[0040] FIG. 4 is an explanatory diagram showing an enlarged view of the structure for attaching the impeller 10 to the shaft 31 of the motor 30 in the blower fan 1 of the first modified example. First, FIG. 4(a) shows the impeller 10 before it is attached to the shaft 31. As shown in the figure, a cylindrical protrusion 11a is provided at the center of the rotating disk 11 of the first modified example. The protrusion 11a protrudes in a generally parallel cylindrical shape from the outer circumferential surface of the tapered portion 31a, and the diameter of the protrusion 11a decreases toward the tip of the shaft 31. The inside of this protrusion 11a forms an insertion hole 14. The maximum inner diameter D5 of the insertion hole 14 of the first modified example is smaller than the maximum outer diameter D3 of the tapered portion 31a, and the minimum inner diameter D4 of the insertion hole 14 is larger than the minimum outer diameter D2 of the tapered portion 31a. When the rotating disk 11 is made of sheet metal, the protrusion 11a can be formed by drawing.

[0041] When the shaft 31 having the vibration-damping member 41 attached to the tapered portion 31a is passed through the insertion hole 14 of the rotating disk 11 of this first modified example, the inner peripheral surface of the insertion hole 14 comes into close contact with the outer peripheral surface of the vibration-damping member 41, as shown in Figure 4(b), thereby positioning the rotating disk 11 relative to the shaft 31. Note that the circle enclosed by the dashed line in Figure 4(b) shows an enlarged view of the contact area between the inner peripheral surface of the insertion hole 14 and the outer peripheral surface of the vibration-damping member 41.

[0042] In the blower fan 1 of this first modified example, the impeller 10 can be fixed to the shaft 31 using the nut 43 and the vibration-proof washer 42, as in the previously described embodiment, so a description thereof will be omitted.

[0043] As described above, in the blower fan 1 of the first modified example, a cylindrical protrusion 11a protrudes from the center of the rotating disk 11 of the impeller 10, the protrusion 11a tapering in diameter toward the tip of the shaft 31 and generally parallel to the outer circumferential surface of the tapered portion 31a, and the inside of this protrusion 11a forms the insertion hole 14. Because the inner circumferential surface of the insertion hole 14 tapers in diameter toward the tip of the shaft 31 and generally parallel to the outer circumferential surface of the tapered portion 31a, the inner circumferential surface of the insertion hole 14 and the outer circumferential surface of the vibration-damping member 41 attached to the tapered portion 31a come into surface contact. This improves the seating of the impeller 10 (rotating disk 11) on the shaft 31 compared to line contact when the inner circumferential surface of the insertion hole 14 has a uniform diameter with no change in inner diameter, making it possible to improve stability.

[0044] Furthermore, by providing a protrusion 11a in the center of the rotating disk 11, it becomes easier to ensure the contact area between the inner surface of the insertion hole 14 and the outer surface of the vibration-damping member 41 attached to the tapered portion 31a, even without making the rotating disk 11 thicker, thereby making it possible to further stabilize the impeller 10 (rotating disk 11) relative to the shaft 31.

[0045] FIG. 5 is an explanatory enlarged view showing the structure for attaching the impeller 10 to the shaft 31 of the motor 30 in the blower fan 1 of the second modified example. First, FIG. 5(a) shows the impeller 10 before it is attached to the shaft 31. As shown in the figure, in the rotating disk 11 of the second modified example, as in the first modified example, the inside of the central cylindrical protrusion 11a forms an insertion hole 14, and the inner circumferential surface of the insertion hole 14 is formed substantially parallel to the outer circumferential surface of the tapered portion 31a. However, the protrusion 11a of the second modified example extends further toward the tip of the shaft 31 than the protrusion 11a of the first modified example. The minimum inner diameter D4 of the insertion hole 14 of the second modified example is larger than the outer diameter D6 of the male thread portion 31b of the shaft 31 and smaller than the minimum outer diameter D2 of the tapered portion 31a. The outer diameter D6 of the male threaded portion 31b formed on the tip side of the tapered portion 31a of the shaft 31 is smaller than the minimum outer diameter D2 of the tapered portion 31a.

[0046] When the shaft 31 having the vibration-damping member 41 attached to the tapered portion 31a is passed through the insertion hole 14 of the rotating disk 11 of this second modified example, the inner surface of the insertion hole 14 is in close contact with the outer surface of the vibration-damping member 41, and as shown in Figure 5(b), the end of the narrow diameter side of the insertion hole 14 does not come into contact with the outer surface of the vibration-damping member 41, and the tip of the protrusion 11a remains protruding toward the male thread portion 31b, and the rotating disk 11 is positioned relative to the shaft 31.

[0047] With the rotating disk 11 positioned relative to the shaft 31 in this manner, the tip of the protrusion 11a protrudes toward the male thread portion 31b, so that, as shown in Figure 5(c), if a typical nut 43 is used to fasten the male thread portion 31b of the shaft 31, the end face of the nut 43 facing the rotating disk 11 will come into contact with the tip face of the protrusion 11a before the female thread portion 43a of the nut 43 reaches the end of the male thread portion 31b on the tapered portion 31a side, and the nut 43 can press against the rotating disk 11 (the tip face of the protrusion 11a), thereby fixing the impeller 10 to the shaft 31. Furthermore, in the blower fan 1 of the second modified example, an annular vibration-damping washer 42 made of an elastic material such as rubber is interposed between the end face of the nut 43 facing the rotating disk 11 and the tip face of the protrusion 11a.

[0048] As described above, in the blower fan 1 of the second modified example, the inside of the cylindrical protrusion 11a provided in the center of the rotating disk 11 serves as the insertion hole 14, the inner circumferential surface of the protrusion 11a (insertion hole 14) is formed approximately parallel to the outer circumferential surface of the tapered portion 31a, and the minimum inner diameter D4 of the insertion hole 14 is larger than the outer diameter D6 of the male thread portion 31b and smaller than the minimum outer diameter D2 of the tapered portion 31a. As a result, when the shaft 31 is passed through the insertion hole 14 of the rotating disk 11 from the tip side, and the inner circumferential surface of the insertion hole 14 comes into contact with the outer circumferential surface of the vibration-damping member 41 attached to the tapered portion 31a, and the impeller 10 is positioned relative to the shaft 31, the tip of the protrusion 11a (the end on the smaller diameter side of the insertion hole 14) does not come into contact with the outer circumferential surface of the vibration-damping member 41 but protrudes toward the male thread portion 31b. Therefore, even when a general nut 43 is used, it is possible to press the tip surface of the protruding portion 11a before the female thread portion 43a of the nut 43 reaches the end of the male thread portion 31b on the tapered portion 31a side, thereby fixing the impeller 10 to the shaft 31. Furthermore, since the vibration-isolating washer 42 is interposed between the tip surface of the protruding portion 11a and the nut 43, it is possible to suppress vibrations transmitted from the shaft 31 to the impeller 10 via the nut 43.

[0049] The present embodiment and various modified examples have been described above, but the present invention is not limited to the above-described embodiment and modified examples, and can be implemented in various forms without departing from the spirit of the present invention.

[0050] For example, in the first and second modified examples described above, the inside of the cylindrical protrusion 11a provided in the center of the rotating disk 11 is used as the insertion hole 14, and the inner peripheral surface of the protrusion 11a (insertion hole 14) is formed approximately parallel to the outer peripheral surface of the tapered portion 31a. However, without providing the protrusion 11a, the thickness of the rotating disk 11 may be left unchanged and the insertion hole 14 may be formed in a truncated cone shape in the center of the rotating disk 11 using a tapered end mill or the like, so that the inner peripheral surface of the insertion hole 14 is approximately parallel to the outer peripheral surface of the tapered portion 31a. Furthermore, when the rotating disk 11 is produced by resin molding, the plate thickness itself may be increased and the inner peripheral surface of the insertion hole 14 provided in the center may be made approximately parallel to the outer peripheral surface of the tapered portion 31a.

[0051] In the above-described embodiment and modified example, the cross section of the tapered portion 31a cut along a plane perpendicular to the axial direction of the shaft 31 is circular. However, the cross section of the tapered portion 31a perpendicular to the axial direction of the shaft 31 is not limited to a circular shape and may be non-circular (for example, D-shaped). In this case, the shape of the vibration-proof member 41 and the shape of the inner side of the insertion hole 14 in the rotating disk 11 may also be made to correspond to the shape of the outer side of the tapered portion 31a. In this way, it is possible to reliably prevent the rotating disk 11 from rotating relative to the shaft 31. [Explanation of symbols]

[0052] 1...blower fan, 10...impeller, 11...rotating disk, 11a...protrusion, 12...slat, 13...connecting plate, 14...through hole, 20...fan case, 21...opening, 22...inlet, 23...outlet, 30...motor, 31... shaft, 31a... tapered portion, 31b... male thread portion, 32...mounting portion, 35...fixing plate, 41...vibration-isolating member, 42...Anti-vibration washer, 43...Nut, 43a...Female thread portion, 43b...cylindrical portion, 43c...flange portion.

Claims

1. In a blower fan that blows air by rotating an impeller attached to the shaft of a motor, The impeller is provided with an insertion hole through which the shaft is inserted, The shaft has a tapered portion whose outer diameter decreases toward the tip end, a covering member formed of an elastic material in a cylindrical shape, the diameter of which decreases toward the tip side of the shaft and which is substantially parallel to the outer circumferential surface of the tapered portion, capable of covering at least a part of the outer circumferential surface of the tapered portion; The impeller has an inner diameter of the insertion hole that is smaller than the maximum outer diameter of the tapered portion, and when attached to the shaft, the inner periphery of the insertion hole is in contact with the outer periphery of the covering member. A blower fan characterized by:

2. The blower fan according to claim 1, The inner peripheral surface of the insertion hole is formed substantially parallel to the outer peripheral surface of the tapered portion. A blower fan characterized by:

3. The blower fan according to claim 2, the impeller has a cylindrical protruding portion at the center of a rotating disk that supports a plurality of blades, the protruding portion being generally parallel to an outer circumferential surface of the tapered portion and having a diameter that decreases toward a tip end of the shaft, The inside of the protrusion serves as the insertion hole. A blower fan characterized by:

4. The blower fan according to any one of claims 1 to 3, The shaft has a male threaded portion formed on a tip side of the tapered portion, the male threaded portion being adapted to thread with the female thread of the nut, a cylindrical portion having an inner diameter larger than that of the insertion hole is provided concentrically with the female screw on a surface of the nut facing the impeller, An elastic body is provided between the end face of the cylindrical portion and the impeller. A blower fan characterized by:

5. The blower fan according to claim 2 or 3, The shaft has a male threaded portion formed on a tip side of the tapered portion, the male threaded portion being adapted to thread with the female thread of the nut, a minimum outer diameter of the tapered portion is larger than an outer diameter of the male thread portion, and a minimum inner diameter of the insertion hole is larger than the outer diameter of the male thread portion and smaller than the minimum outer diameter of the tapered portion, An elastic body is provided between the nut and an end face of the insertion hole on the small diameter side of the impeller. A blower fan characterized by:

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