JPH025791A - Axial fan - Google Patents

Abstract

PURPOSE:To suppress noise without making air capacity small by installing a cylinder made of plural concentric thin cylinder members between an inlet port and a bucket. CONSTITUTION:The rotary axis of a motor 2 juts out toward the side of an inlet port 1a and a bucket 5 for sending wind to discharge port side is coaxially installed thereto. The outside diameter of this bucket 5 is a little smaller than the inside diameter of a case 1 and a gap g is present between them. Between the discharge port and the bucket 5, there lies a member 4 which becomes a resistance against wind flow. The outer most thin cylinder member 6a of a cylinder 6 consisting of plural thin cylinder members 6a, 6b, 6c has a smaller outside diameter than the inside diameter of the case 1 and further the outside diameter of the bucket 5 to form a space S1. Between the thin cylinder members 6a and 6b; and 6b and 6c, a little smaller space S2 than the space S1 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an axial flow fan that sends air in the axial direction of rotor blades suitable for hair dryers and the like.

[Prior Art] In recent years, office automation equipment and home appliances have become more compact, and blowers are also required to be small, highly efficient, and generate large amounts of air and low noise.

As general blowers, there are sirocco type fans and single flow type fans. In these cases, during the discharge period between the rotor blades and the blower, there are no components such as motors, circuit parts, or heaters that create resistance to the wind flow, or even if they are present, the required pressure P - wind iQ characteristics can be obtained, but the current It consumes a lot, has low efficiency, and is difficult to adapt to miniaturization.

In addition, there is an axial fan that blows air in the axial direction of the rotor blades, which has low current consumption, high efficiency, and can be easily adapted to miniaturization. However, even in this case, it is difficult to say that the air flow is smooth because there is a member that acts as a resistance to the air flow between the rotor blades and the blower. descend.

[Problem to be Solved by the Invention 1] In the conventional axial fan, it is hard to say that the air flow is smooth as described above. That is, as in No. 8 and 1,
The wind flow Wl in case A, which has a cylindrical shape and has one end for suction and the other end for discharge, is caused by the moving blades B and members that act as resistance to the wind flow between the blower and the blower.
Stall occurs on the 8 surfaces of the rotor blades because the rotor blades cannot maintain a parallel state with the axis. Then, in the range indicated by X, part of the flow becomes the opposite flow W2, and in the range indicated by Y, both flows WIW2
collide, and a vortex W3 is generated. Therefore, this collision generates noise (turbulence noise) and lowers the wind pressure or wind wall.

The present invention has been made in view of the above reasons, and its purpose is to provide an axial flow fan that does not reduce air volume and has low noise.

[Means for Solving the Problems] In order to solve the problems, the axial fan of claim 11 is provided with It consists of a rotor blade and a cylindrical case with one end for suction and the other end for discharge, in which parts including the motor and rotor blades are housed and fixed, and the air flows between the discharge port and l1rl]vfj. In an axial fan in which there is a member that acts as resistance, a cylindrical body consisting of a plurality of concentric thin-walled cylindrical members is arranged between the suction port and the rotor blade, and the thin-walled cylindrical body is arranged between the case and the outermost thin-walled cylindrical member and A space is formed between the cylindrical members.

In the axial fan according to claim (2), the end surface of the cylindrical body on the suction port side in claim (1) is located inside one end surface of the case.

The axial fan according to claim (3) is the same as the axial fan according to claim fl) or claim (2), wherein the large diameter part is joined to one end of the case and the straight pipe-shaped small diameter part enters inside the cylindrical body. A bell mouth is provided to form a space between the cylindrical body and the small diameter portion.

In the other flow fan of claim (1), by disposing a cylindrical body made of a plurality of concentric thin-walled cylindrical members, the main flow discharged from the main flow and the reverse flow opposite thereto are separated and collide with each other. can be suppressed.

In addition to the above-mentioned action, the axial flow fan of claim (2) is configured such that the reverse flow is attracted by the viscosity of the main flow into which it has been sucked, and joins the main flow again by utilizing the space between the thin cylindrical members. Become.

In addition to the above-described effects, the axial fan of claim (3) allows the backflow to be more reliably recovered to the main stream by the bell mouth, and furthermore shields noise from the rotor blades.

Embodiment] A first embodiment in which the axial fan of the present invention is applied to a hair dryer will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a side sectional view of the hair dryer cut along the central axis, showing only one side of the substantially symmetrical axis.

2 is a plastic case having a substantially cylindrical shape, with one end serving as an inlet port 1a and the other end serving as an outlet port (not shown). Inside the case 1 between the suction port 1a and the discharge port, there is a motor 2, such as a brushless motor of about 1600 Q rpm, a guide vane 3 located around the motor 2, and a rotation! A member 4 that acts as a wind flow resistance, such as a loft or a heater, is accommodated and fixed. The rotary shaft of the motor 2 protrudes toward the suction port 1a, and a rotor blade 5 that sends air in the axial direction, that is, in the direction of the discharge direction, is coaxially attached to this rotary shaft. The outer diameter of the rotor blade 5 is slightly smaller than the inner diameter of the case 1, and a gap g exists between them.

Therefore, a member 4 that acts as a resistance to the flow of wind is interposed between the outlet and the rotor blades 5.

Reference numeral 6 denotes a cylindrical body consisting of a plurality of concentric thin cylindrical members 6a, 6b, and 6c (in this embodiment, 3 (IM)), and the outermost thin cylindrical member 6a is closer to the inner diameter of the case 1 and further to the rotor blade 5. It is desirable that the outer diameter be smaller than the outer diameter, and that the distance between this and the inner diameter of the case 1 be 10 times or less the above-mentioned gap g, so that a space S1 is formed between the case 1 and the thin cylindrical member 6a.

Further, a space S2, which is slightly smaller than the space S1, is formed between the thin cylindrical members 6a, 6b, and 6c. It is desirable that the axial length of this cylindrical body 6 is shorter than that between the suction port 1a and the rotor blade 5. 6d is a thin-walled cylindrical member 6a, 6b, 6c.
The outermost thin rib 6d is fixed to the case 1 by press-fitting or adhesion. In addition to the method of forming the cylindrical body 6 separately from the case 1 as described above, the cylindrical body 6 may be molded integrally with the case 1.

Furthermore, it is desirable that the end surface 6e of the cylindrical body 6 on the side of the suction port la is located inside one end surface of the case l.

7 is a suction net provided in front of the suction port 1a.

In such an axial flow fan, as shown in FIG.
Due to the member 4 that acts as a resistance to the wind flow interposed between the moving g, 5 and the outlet 1, the air flow Wl inside cannot maintain the parallel state with the axis line as in the conventional example, and the moving In the vicinity of the tip of the blade 5 on the suction port la side, that is, in the range indicated by X, a part becomes a reverse flow (reverse swirling flow) W2. By the way, this flow (reverse flow) W2 flows through the space S1 formed between the case 1 and the cylindrical body 6, and is prevented from being separated from and colliding with the flow (main flow) Wl.

As a result, the generation of vortices is also suppressed, and the noise of conventional turbulence can be reduced by about 1 to 2 dB.

Furthermore, when the flow (reverse flow) W2 reaches the vicinity of the end surface on the suction port la side of the cylindrical body 6, the flow that has been sucked in (main flow)
attracted by the viscosity of Wl, the thin cylindrical member 6a,
Using the space S2 between 6b and 6c, much of it flows again (main stream > Wl).As a result, much of what was previously wasted outside Case I can be recovered.
++3 to 5 compared to when the rotation speed of Jm5 is the same
% air volume amplifier, in other words, the reduction in air volume due to the member 4 serving as a resistance can be suppressed. FIG. 4 compares the present invention with the conventional example regarding pressure P-wind fiQ characteristics. In the conventional example, the drop in wind pressure due to the generation of vortices is quite large, but in the present invention, this is reduced.

In addition, if the air volume is the same as that of the conventional example, motor 2
The rotational speed of the engine is lowered by about 100 rpm (a little less than 6 to 8%), thereby making it possible to further reduce the noise by about 1 to 2 dB.

Next, a second embodiment in which the axial fan of the present invention is applied to a hair dryer will be described based on FIGS. 5 and 6.

FIG. 5 is a side cross section IX+ of the hair dryer cut along the central axis, showing only one side of the substantially symmetrical axis.

This device has a bell mouth, which will be described later, added to the first embodiment, and other members are substantially the same as those in the first embodiment. Omitted.

The bell mouth 28, which is approximately trumpet-shaped, has a large diameter portion 28a having an outer diameter between the case 1 and the passage, and a small diameter portion 28b formed in a straight tube shape smaller than the inner diameter of the innermost thin-walled cylindrical member 6C. . The outer diameter of this straight tubular portion is such that the gap between it and the thin cylindrical member 6C is the same as that between the case 1 and the outermost thin cylindrical member 6a.
The gap should be approximately equal to the gap between Further, the length of the straight tubular portion is desirably at least half the length in the axial direction of the cylindrical body 6, but it may be shorter than this if there is a curved portion.

Thus, the large diameter portion 28a of the bell mouth 28 is joined to one end of the case 1 by clamping or adhesive, and the straight pipe-shaped small diameter portion 28b enters inside the cylindrical body 6, so that the bell mouth 28 is connected to the cylindrical body 6 in the axial direction. It is desirable that at least half of them overlap. Therefore, a space S3 can be formed between the cylindrical body 6 and the small diameter portion 28b.

In this axial flow fan, in addition to the same effect as in the first embodiment, the bell mouth 28 more reliably recovers the flow (reverse flow) W2 into the flow (main flow) Wl, and furthermore, Approximately 3 to 4 d including noise shielding and turbulence noise
The noise of B can be reduced.

FIG. 7 is a cross-sectional view of the dryer according to the second embodiment.

Although the cylindrical body 6 of each embodiment has been described as being composed of three thin-walled cylindrical members, it is needless to say that the number is not limited to this number.

Effects of the Invention] Since the axial fan of the present invention is configured as described above, it has the following effects.

The axial flow fan according to claim 11 is provided with a cylindrical body made of a plurality of concentric thin-walled cylindrical members, so that the discharged main flow and the opposite reverse flow can be separated and prevented from colliding with each other, Therefore, noise can be reduced.

In addition to the above-mentioned action, the axial flow fan of claim (2) is configured such that the reverse flow is attracted by the viscosity of the main flow into which it has been sucked, and joins the main flow again by utilizing the space between the thin cylindrical members. Therefore, deterioration in quality and forgeries can be suppressed.

In addition to the above-mentioned effects, the axial flow fan of claim (3) more reliably recovers the backflow to the main stream by the bell mouth, and further shields noise from the rotor blades, thereby further suppressing the reduction in wind clearness. , and can further reduce noise.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of the first embodiment, Fig. 2 is a perspective view of its main parts, Fig. 3 is an explanatory diagram of its operation, Fig. 4 is a wind pressure-air volume characteristic diagram, and Fig. 5 is a side sectional view of the second embodiment, FIG. 6 is an explanatory diagram of its operation, FIG. 7 is a sectional view of a hair dryer that is used in the second embodiment, and FIG. 8 is a side sectional view of the conventional example. It is. ■-...Case, la...Suction port, 2-Motor,
3-Guide blade, 4...-Resistance member, 5-@wing, 6-
Cylindrical body, 6a, 6b, 6c...~Thin cylindrical member, 7...
Suction net, 28-・bell mouth, 28 a-m
- large diameter part, 28b - small diameter part, Wl - main flow, W2 - continuous flow, g - gap, SL, S2. S3 space.

Claims (3)

[Claims] (1) A motor, a rotor blade coaxially attached to the rotating shaft of the motor to send air in the axial direction, and a cylindrical blade with one end as a suction port and the other end as a discharge port, and the motor and rotor blades are connected between them. In an axial fan, which consists of a case that houses and fixes parts including the rotor blades, and in which there is a member that acts as a wind flow resistance between the outlet and the rotor blades, there are multiple concentric parts between the suction port and the rotor blades. An axial fan in which a cylindrical body made of a thin cylindrical member is arranged to form a space between the case and the outermost thin cylindrical member and between the thin cylindrical members. (2) The axial fan according to claim (1), wherein the end surface of the cylindrical body on the suction port side is located inside one end surface of the case. (3) Claim (1) or (2) wherein a bell mouth is provided in which the large diameter part is joined to one end of the case and the straight pipe-like small diameter part enters inside the cylindrical body to form a space between the cylindrical body and the small diameter part. ) Axial fan as described.