JPS6270694A - Motor fan - Google Patents

Abstract

PURPOSE:To realize a large air flow and a low noise motor fan, by furnishing the second vane rotating in the same direction and in the same cycle as the first vane, between the first vane and a rib. CONSTITUTION:A cylindrical casing 4 envelopes a motor 2, the first vane 3, and the second vane 7. The second vane 7 is between the first vane 3 and a rib 5, and rotates in the same direction and in the same cycle as the first vane 3. The second vane 7 is installed at a rotor 8 turning in the same direction nd in the same cycle as the hub 9 of the first vane 3. Therefore, a compact and a large air flow motor fan with a low noise is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an axial fan used for cooling electronic equipment, etc.

[Background technology]

In recent years, as OAi equipment has progressed and become more compact, there has been a need for small, yet large-sized fans for cooling electronic components. As shown in FIG. 6, a conventional motor fan 11 for cooling electronic components includes a motor 1 having a rotor blade 13 attached to its tip.
2 is supported by ribs 15 within a cylindrical casing 14. In order to make such a motor fan 11 small and to prevent the air volume from decreasing, the number of rotations of the rotor blades 13 may be increased. For example, if the blade span of the rotor blade is reduced to 1/2, the number of rotations should be increased eight times in order to obtain the same amount of air. However, if you do this,
A problem arises in that the noise becomes louder.

[Purpose of the invention]

In view of the above, an object of the present invention is to provide a small fan with a large air volume and low noise.

[Disclosure of the invention]

In order to achieve the above object, the present invention includes a motor, a first rotor blade attached to the tip of the motor and driven by the motor, a cylindrical casing that encloses the motor and the first rotor blade. In the motor fan, each of which includes a rib that supports and fixes the motor to the cylindrical casing at the other end, between the first rotor blade and the rib,
A second rotor blade is provided which rotates in the same direction and at the same period as the first rotor blade.
l! The main focus is on motor fans.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows one embodiment of this invention. As shown in FIG. 1, this motor fan 1 includes a motor 2, a first rotor blade 3, a second rotor blade 7, a cylindrical casing 4, and a rib 5. The illustrated part is
This is the rotor 8. The first moving blade 3 is attached to the tip of the motor 2 and is driven by the motor 2. A cylindrical casing 4 encloses the motor 2, the first rotor blade 3, and the second rotor blade 7. The cylindrical casing is often cylindrical, but may have other shapes. The rib 5 supports and fixes the motor 2 to the cylindrical casing 4 at the other end (the side opposite to the side to which the first rotor blade 3 is attached, which is also the downstream side of the flow). Second
The rotor blade 7 is located between the first rotor blade 3 and the rib 5 and rotates in the same direction and at the same period as the first rotor blade 3. The second rotor M7 is provided in the rotor portion 8 that rotates in the same direction and at the same period as the hub 9 of the first rotor blade 3.

Figure 2 fat, (bl is an example of the shape of the first rotor blade 3. Of course, the number of blades is not limited to one and may be two or more. Figure 3 (al, (bl is , is an example of the shape of the second rotor blade 7.Of course, the number of blades is not limited to one, but may be two or more.The first rotor blade and the second rotor blade have the same number. It is preferable that the number of sheets is different, but the number of sheets may be different.
(b) does not show the blades at the same position in the rotational direction, but shows one side shifted so that the center of the blade is in the front. The positional relationship in the rotational direction between the first rotor blade and the second rotor blade is, for example, as shown in FIG. In the case of this motor fan, it has a single blade configuration with only the rotor blades 13, so simply increasing the area of the rotor blades 13 does not increase the pressure much.The characteristics of this conventional motor fan are shown in Fig. 5. It is indicated by D on the graph.

In contrast, in the present invention, two of the first rotor blade and the second rotor blade are
Heavy wing configurations are effective in increasing pressure. As shown in Figure 4, the area of the rotor blades increases, so the air volume increases. Moreover, when the length of only the first rotor blade is increased to increase the area of the rotor blade, a vortex is generated, but this can be prevented by dividing the blade into a double blade configuration. . Therefore, the flow in the axial direction increases, and the characteristics improve as shown by C in the graph of FIG. In other words, the air volume increases.

Note that if the gap δ1 between the first rotor blade and the second rotor blade is too large, the effect of increasing the area of the rotor blade cannot be obtained, and if it is too small, the effect of dividing the rotor blade by creating a double blade configuration cannot be obtained. There is a risk that it will disappear. For this reason, it is preferable to set it to an appropriate size.

As shown in FIG. 2 (bl) and FIG. The rotor blade is preferably provided such that its upstream end is along the downstream end of the first rotor blade.

Therefore, in this embodiment, the second moving blade 7 is arranged so that its center is at ψ=45° with the normal direction of the rotor 8.
It is attached to the rotor 8.

In this embodiment, the rib 5 has a guide vane 6 extending towards the side on which the second rotor blade 7 is located. Therefore, the guide vanes can be provided without increasing the size of the motor fan. If the lip and the guide vane are integrally formed from the beginning, the number of parts and manufacturing steps will not be increased.

If there is no guide vane 6, the flow flowing out from the second dynamic R7 becomes a swirling flow along the inner circumference of the casing 4 and flows out from the casing 4, so that swirling energy is not consumed as loss. In this embodiment, as shown in FIG. 1, a guide vane 6 is provided behind the second rotor blade 7 (on the downstream side of the flow), so that the flow along the inner circumference of the casing 4 is guided by the guide N6. The swirling energy of the flow is converted into pressure to produce an axial flow, which is directed along the guide vanes 6, as shown in FIG. For this reason, the characteristics are further improved as shown by F in the graph of FIG. In other words, the air volume is further increased. In FIG. 5, F shows the characteristics of the motor fan of the present invention with guide vanes.

It is preferable that the number of second rotor blades and the number of guide blades have a mutually prime relationship, that is, the number of second rotor blades should not be an integral multiple of the number of guide blades.

It is not limited to this. If this relationship does not exist, there is a possibility that the air volume cannot be increased much.

In this embodiment, there are nine first rotor blades and nine second rotor blades, and five guide blades.

The gap δ2 between the second rotor blade 7 and the guide blade 6 is the blade span of the second rotor blade 7 (the length in the radial direction of the blade) p, 1 of 2.
It is preferably 0 to 30%. δ, <0.1j! If it is z, the noise (wind noise) may become louder,
If δZ>0.312, the above-mentioned rectifying effect may not be obtained, and there is a possibility that the air volume will not increase.

Even if a guide vane is provided, if the guide vane is almost perpendicular to the rotational direction of the second rotor blade on the side where the second rotor blade is located, when the rotor blade is rotated, the guide vane Separation vortices may occur at the tip. This results in energy loss and noise generation. In contrast, Figures 1 and 4
As shown in the figure, if the guide blade 6 is inclined in the direction opposite to the second rotor blade rotation direction A on the side where the second rotor blade 7 is located, the guide blade 6 The tip of the guide blade 6 is oriented in the opposite direction to the outflow direction of the flow E (direction of the arrow E), so that no peeling vortex is generated at the tip of the guide vane 6. Therefore, the flow flows out smoothly along the guide vanes 6, reducing loss, increasing air volume, and reducing noise.

Angle θ between the inclination of the guide blade 6 and the second moving blade rotation direction A
is preferably 50 to 806. If θ is 50°, the inclined portion of the guide vane will act as resistance to the flow, reducing the pressure and potentially preventing an increase in air volume. If θ>80°, it is almost the same as when there is no inclination of the guide vanes, and there is a risk that the blowing vortex will not disappear and the air volume will not increase due to the pressure drop. In addition, rotation speed 14000 rpm, flow rate 0.35%
/min, the best effect can be obtained by setting θ within that range.

Note that this invention is not limited to the above embodiments.

The motor fan of your invention can be made smaller than a conventional fan for the same air flow, and has a larger air volume than a conventional fan for the same size. Therefore, the air volume can be increased without increasing the rotational speed of the motor, and noise can also be reduced. For example, if the motor fan of the present invention is used in electronic equipment to cool parts, noise can be reduced in an environment where such electronic equipment is installed. Moreover, it can be used for smaller electronic devices.

Note that the application of the motor fan of the present invention is not limited to this.

〔Effect of the invention〕

Since the motor fan of the present invention is as described above, it can be made smaller, have a larger air volume, and have lower noise than conventional ones.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of one embodiment, Fig. 2 is a fan, (b
FIG. 3(a) is an explanatory diagram of the shape of the first wing of the embodiment. (bl is an explanatory diagram of the shape of the second rotor blade in the example, Figure 4 is an explanatory diagram of the flow generated by the rotation of the first rotor blade and the second rotor blade, and Figure 5 is the characteristic of the motor fan. Figure 6 is a side sectional view of the conventional example. 1...Motor fan 2...Motor 3...First
Movement M 4...Cylindrical casing 5...Rib 7
...Second moving agent Patent attorney Takehiko Matsumoto Figure 1 Figure 2 Figure 3 (a)

Claims (7)

[Claims] (1) A motor, a first rotor blade attached to the tip of the motor and driven by the motor, a cylindrical casing that encloses the motor and the first rotor blade, and a cylindrical casing that encloses the motor at the other end. In the motor fan, a second rotor blade is provided between the first rotor blade and the rib and is configured to rotate in the same direction and at the same period as the first rotor blade. A motor fan characterized by being provided with rotor blades. (2) The motor fan according to claim 1, wherein the second rotor blade is provided at a position following the first rotor blade. (3) Claim 1 or 2, wherein the rib has a guide vane extending toward the side where the second rotor blade is located.
Motor fan as described in section. (4) The motor fan according to claim 3, wherein the guide blade is inclined on the side where the second rotor blade is located in a direction opposite to the rotational direction of the second rotor blade. (5) The inclination of the guide blade is 50 to 80 degrees with respect to the second rotor blade rotation direction.
The motor fan according to claim 4, wherein the motor fan forms an angle of .degree. (6) The motor fan according to any one of claims 3 to 5, wherein the gap between the second rotor blade and the guide blade is 10 to 30% of the blade span of the second rotor blade. (7) The motor fan according to any one of claims 1 to 6, which is used for cooling electronic equipment.