BLOWER DEVICE

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-21395, filed on Feb. 8, 2017, the entire contents of which are incorporated herein by reference.

BACKGROUND
(i) Technical Field

The present invention relates to a blower device.

(ii) Related Art

There is conventionally known a blower device equipped with a fan that is driven by a motor and is housed within a case (see, for example, Japanese Unexamined Patent Application Publication No. 2005-299433). The rotation of the fan introduces air from an air inlet of the case thereinto, which discharges air from an outlet of the case.

SUMMARY

According to an aspect of the present invention, there is provided a blower device including: a fan; a case housing the fan for rotation; and a motor of an outer rotor type fixed to an outer surface of the case and rotating the fan, wherein the motor includes: an outer rotor; and a rotatable shaft rotating together with the outer rotor, the fan includes: a hub fixed to the rotatable shaft; a main plate rotating together with the hub; and blades provided on a first surface of the main plate and provided radially about the hub, the case includes an air inlet through which air is introduced into the case from an outside by rotation of the fan and through which an axis of the rotatable shaft passes through, R indicates an outer diameter of the fan, r indicates an outer diameter of the outer rotor, D indicates an inner diameter of the air inlet, d indicates an outer diameter of the hub, H indicates a maximum height of the blades from a second surface of the main plate opposite to the first surface in a direction of the axis of the rotatable shaft, h indicates a maximum height of the hub from the second surface of the main plate in the direction of the axis of the rotatable shaft, and (r/R)≥0.35, 0<(d/D)<0.5, and 0<(h/H)<0.5 are satisfied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of a blower device according to the present embodiment;

FIG. 2 is an external view of the blower device according to the present embodiment;

FIG. 3 is a sectional view taken along line A-A of FIG. 1;

FIG. 4 is a sectional view of a blower device according to a comparative example; and

FIG. 5A is a table illustrating ratios of dimensions between the present embodiment and the comparative example, and FIG. 5B is a graph illustrating a comparison between the present embodiment and the comparative example in fan efficiency.

DETAILED DESCRIPTION

FIGS. 1 and 2 are external views of a blower device A according to the present embodiment. FIG. 3 is a sectional view taken along line A-A of FIG. 1. The blower device A includes cases 10 and 20, a motor M, a fan 80, and the like. The cases 10 and 20 are half case bodies assembled into each other from an axial direction TD of a rotatable shaft 42 of the motor M, which will be described later. The cases 10 and 20 cooperatively define a single scroll shaped case. The cases 10 and 20 are made of, but not limited to, a synthetic resin. The case 10 includes a circumferential wall portion 12, an upper wall portion 14, and a projecting wall portion 18. The circumferential wall portion 12 surrounds the outer circumferential portion of the fan 80 and has a substantially cylindrical shape. The upper wall portion 14 is continuous with the circumferential wall portion 12 and positioned axially above the fan 80. The upper wall portion 14 is positioned in the upper side in the axial direction of the fan 80. An air inlet 15a is formed in the upper wall portion 14. An upper portion of the fan 80 is partially exposed from the air inlet 15a. The projecting wall portion 18 extends partially radially outward from the circumferential wall portion 12 and the upper wall portion 14.

The case 20 includes a circumferential wall portion 22, a bottom wall portion 24, and a projecting wall portion 28. The circumferential wall portion 22 surrounds the outer circumferential portion of the fan 80 and has a substantially cylindrical shape. The circumferential wall portions 12 and 22 are fixed to each other. The bottom wall portion 24 is positioned in the lower side in the axial direction of the fan 80 and is continuous with the circumferential wall portion 22. An escape hole 25 is provided substantially at the center of the outer side of the bottom wall portion 24. As will be described later in detail, a holder 60 of the motor M fixed to the bottom wall portion 24 penetrates though the escape hole 25. That is, the fan 80 is housed within in the cases 10 and 20, and the motor M is arranged outside the cases 10 and 20. The motor M will be described later in detail. The projecting wall portion 28 extends partially and radially outward from the circumferential wall portion 22 and the bottom wall portion 24. The projecting wall portions 18 and 28 are fixed to each other. The projecting wall portions 18 and 28 define a single air outlet 15b. The rotation of the fan 80 introduces air from the air inlet 15a, and air flows within the case 10 and 20, which discharges air from the air outlet 15b.

The fan 80 includes a hub 82, a main plate 84, an annular shroud 86, and blades 88. The fan 80 is made of a synthetic resin, but is not limited thereto. The hub 82 is fixed to a distal end of the rotatable shaft 42 of the motor M. The main plate 84 is fixed to the hub 82 and has a substantially disk shape. The main plate 84 includes: a surface 84a facing the air inlet 15a; and a surface 84b opposite to the surface 84a and facing the case 20. The surface 84a is an example of the first surface. The surface 84b is an example of the second surface. On the surface 84a of the main plate 84, the blades 88 are provided radially around the hub 82 at predetermined intervals in the circumferential direction. The annular shroud 86 is provided so as to sandwich the blades 88 with the main plate 84, and an opening 86a is formed in the center of the annular shroud 86. The rotation of the fan 80 introduces air from the opening 86a through the air inlet 15a to the space between the blades 88, and the air discharged from the radially outer side of the blades 88 is discharged from the air outlet 15b to the outside. Additionally, the hub 82 produced separately from the main plate 84 and the blades 88 is fixed to the main plate 84, but these may be integrally formed.

The motor M will be described. The motor M includes coils 30, a rotor 40, a stator 50, the holder 60, a printed circuit board PB, a support plate 70, and the like. The support plate 70 supports the holder 60 and the printed circuit board PB and is fixed to the bottom wall portion 24 of the case 20 by screws S. The holder 60 is fitted in a fitting hole formed in the support plate 70 and is supported thereby. The printed board PB is fixed to a surface of the support plate 70 opposite to the surface thereof fixed to the bottom wall portion 24. The holder 60 is formed into a substantially cylindrical shape. The holder 60 holds the rotatable shaft 42 for rotation through bearings in an inner circumferential side. The holder 60 is fixed such that the stator 50 is fitted onto an outer circumferential side thereof. The distal end of the rotatable shaft 42 projecting from the holder 60 into the case 10 is fixed to the hub 82 as described above. A proximal end of the rotatable shaft 42 is fixed to a connecting member 43. A yoke 44 is fixed to the outer circumferential side of the connecting member 43. Therefore, the rotation of the yoke 44 causes the connecting member 43 and the rotatable shaft 42 to rotate, whereby the fan 80 rotates together with the rotatable shaft 42.

The stator 50 is made of metal and has a shape to have teeth portions radially projecting outward from the annular portion through which the holder 60 penetrates. A coil 30 is wound around each tooth portion of the stator 50. The coil 30 is electrically connected to the printed circuit board PB. The printed circuit board PB has a conductive pattern formed on an insulating substrate with rigidity. An opening PB1 through which the holder 60 penetrates is formed in the printed board PB, and electronic components for supplying electric power to the coil 30 are mounted on the printed board PB. The electronic components are, for example, a component for controlling the energization state of the coil 30, a magnetic sensor whose output varies depending on the rotation of the rotor 40, and the like. The energization of the coil 30 excites the stator 50.

The rotor 40 includes a rotatable shaft 42, a yoke 44, and one or more permanent magnets 46. The yoke 44 has a substantially cylindrical shape and is made of metal. One or more permanent magnets 46 are fixed on an inner circumferential side surface of the yoke 44. In the yoke 44, vent holes 44a are provided around the rotation shaft 42 to promote heat dissipation of the motor M. The permanent magnet 46 faces the outside of the teeth portion of the stator 50. The energization of the coil 30 excites the teeth portion of the stator 50, which exerts magnetic attractive force and repulsive force between the permanent magnet 46 and the teeth portion, whereby the yoke 44, that is, the rotor 40 rotates relative to the stator 50. In this way, the motor M is an outer rotor type motor in which the rotor 40 rotates.

An inner rotor type motor is not used as described above, but the outer rotor type motor M is used in the present embodiment. Herein, to ensure the same output, the outer rotor type motor M may be thinner than the inner rotor type motor in the axial direction TD. This thins the blower device A in the axial direction TD.

Herein, a diameter D indicates an inner diameter of the air inlet 15a as illustrated in FIG. 3. A diameter d indicates an outer diameter of the hub 82. Specifically, the diameter d indicates a diameter of a portion projecting from the surface 84a of the blade 88 toward the air inlet 15a and projecting highly than a quarter of the maximum height from the surface 84a of the blade 88. In the present embodiment, the height of the hub 82 is adjusted to be substantially the same height as the distal end of the rotatable shaft 42 so as not to project toward the air inlet 15a side from the blades 88. A height H indicates the maximum height of the fan 80 in the axial direction TD, specifically, the maximum height from the surface 84b of the main plate 84 to the annular shroud 86 in the axial direction TD. A height h indicates the maximum height of the hub 82 in the axial direction TD, specifically, the maximum height of the hub 82 from the surface 84b of the main plate 84 to the air inlet 15a side in the axial direction TD. Also, a diameter r indicates an outer diameter of the yoke 44 of the rotor 40. A diameter R indicates an outer diameter of the fan 80.

Next, a comparative example will be described. FIG. 4 is a sectional view of a blower device Ax according to a comparative example. FIG. 4 corresponds to FIG. 3. In the comparative example, components similar to those of the present embodiment are denoted by similar reference numerals, and duplicate explanation will be omitted.

In the blower device Ax, a motor Mx as well as the fan 80x is housed in cases 10x and 20x. Therefore, the shape of the fan 80x is formed so as to receive the motor Mx, specifically, a hub 82x is formed to rise greatly from a main plate 84x. In addition, a distal end of the hub 82x and a distal end of the rotatable shaft 42x project outward from an air inlet 15ax. Herein, like the present embodiment, in the comparative example, a diameter Dx indicates an inner diameter of the air inlet 15ax, and a diameter dx indicates an outer diameter of the hub 82x. A height Hx indicates the maximum height of the fan 80x in the axial direction TD. A height hx indicates the maximum height of the hub 82x in the axial direction TD. Specifically, the height hx indicates the maximum height of the hub 82x from the surface 84bx of the main plate 84x to the air inlet 15ax side in the axial direction TD. Further, a diameter rx indicates an outer diameter of a yoke 44x of a rotor 40x. A diameter Rx indicates an outer diameter of the fan 80x.

FIG. 5A is a table illustrating ratios of dimensions between the present embodiment and the comparative example. In the present embodiment, d/D is about 0.3, whereas in the comparative example dx/Dx is about 0.7. This means that a ratio of the diameter dx to the diameter Dx is high in the comparative example, whereas a ratio of the diameter d to the diameter D is low in the present example. Further, h/H is about 0.2 in the present embodiment, whereas hx/Hx is about 1.6 in the comparative example. This also means that a ratio of the height hx to the height Hx is high in the comparative example, whereas a ratio of the height h to the height H is low in the present embodiment. Thus, the size of the hub 82x is large as compared with the inner diameter of the air inlet 15ax and the height of the blades 88x in the comparative example, whereas the size of the hub 82 is small as compared with the inner diameter of the air inlet 15a and the height of the blades 88 in the present embodiment. Therefore, the present embodiment reduces the pressure loss of the air introduced into the cases 10 and 20 from the air inlet 15a due to the hub 82, as compared with the comparative example.

FIG. 5B is a graph comparing the fan efficiencies of the present embodiment and the comparative example. These fan efficiencies are calculated by multiplying the flow rate by the static pressure and dividing it by the input electric power. The hub 82 is reduced in size in the present embodiment as described above, so that the fan efficiency is higher than that of the comparative example.

Further, as illustrated in FIG. 5A, r/R is 0.5 in the present embodiment, whereas rx/Rx is 0.3 in the comparative example. This means that a ratio of the diameter rx to the diameter Rx is low in the comparative example, whereas a ratio of the diameter r to the diameter R is high in the present example. This is because the motor M is fixed to the outside of the cases 10 and 20 and the size of the motor M can be determined without being restricted by the shape of the fan 80 in the present embodiment unlike the comparative example. Herein, as described above, the diameters r and rx respectively indicate the outer diameters of the yokes 44 and 44x, and the diameters R and Rx respectively indicate the outer diameters of the fans 80 and 80x. In addition, the rotation of the yokes 44 and 44x by magnetic force transmits the rotational power thereof to the fans 80 and 80x via the rotatable shafts 42 and 42x, which rotates the fans 80 and 80x, respectively. As described above, in the present embodiment, the outer diameter of the yoke 44, which is a portion to generate the rotational power, is larger than the outer diameter of the fan 80, which is a member to be rotated. This suppresses the swinging of the rotatable shaft 42, thereby suitably rotate the fan 80.

In the present embodiment, the following expressions are preferably satisfied.

(r/R)≥0.35 (1)

0<(d/D)<0.5 (2)

0<(h/H)<0.5 (3)

It is thus possible to suppress deterioration in the fan efficiency and to stably rotate the fan 80.

As described above, the motor M is fixed to the outer surface of the motor the case 20 in the present embodiment, whereas the motor Mx is housed within the cases 10x and 20x in the comparative example. Therefore, the present embodiment accelerates heat radiation of the motor M to outside air.

Also, the yoke 44 is formed with the vent holes 44a as described above. Further, as illustrated in FIG. 3, the printed circuit board PB faces the outer rotor 40 via a predetermined gap therebetween such that air can pass therebetween. This accelerates heat dissipation inside the yoke 44 and heat dissipation of electronic components mounted on the printed circuit board PB.

While the exemplary embodiments of the present invention have been illustrated in detail, the present invention is not limited to the above-mentioned embodiments, and other embodiments, variations and modifications may be made without departing from the scope of the present invention.

BLOWER DEVICE

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Priority Claims (1)