JPH01247797A - Fan - Google Patents

Abstract

PURPOSE:To improve fan characteristics and reduce noise by a method wherein a front edge of the circumferential section is jointed with the front rim of a blade and a rear edge is jointed with an outmost circumferential section respectively via an arc section so that a rectifying wing part is formed. CONSTITUTION:A fan 11 consists of a boss 12 and a number of blades 13. A blade 13 consists of a front rim 14 which extends in a direction of a radius, another front rim 14 which extends in a direction of a radius and an outmost circumferential section 15 in an arc shape. A front edge at the tip of the blade 13 is cut so that a circumferential section 16 having a diameter smaller than that of the outmost circumferential section 15 is provided. The front edge of the circumferential section 16 is jointed with the front rim 14 via an arc 17. The rear edge of the circumferential section 16 is also jointed with the outmost circumferential section 15 via an arc 18. A rectifying wing part 19 is formed on the circumferential section 16. This modifies flow in a fan wing, improving fan characteristics and reducing noise.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a fan used as a blower for an air conditioner, for example.

(Prior Art) An axial flow (mixed flow) fan is used as a blower for an air conditioner. As shown in FIGS. 10 to 12, for example, this fan is composed of a boss 1 and a plurality of blades 2..., each blade 2... A radially extending front edge 3 and a tip portion 4 are smoothly joined via a circular arc portion 5. That is, the tip portion 4 is the maximum outer diameter portion of the fan, and is formed into an arcuate surface centered on the boss 1.

However, LDV shows that the fan configured as described above does not work on the air volume in the range of about 5% of the maximum outer diameter from the tip 4 of the blade 2 toward the boss 1. This was revealed by measuring the flow velocity inside the blade using a laser Doppler anemometer (laser Doppler anemometer). That is, FIG. 13(A) (
The wind will flow as shown in B). Here, the vortex is turbulent,
The arcuate arrow represents the flow of wind from the positive pressure surface 6 to the negative pressure surface 7, and the broken line represents the boundary line between the part doing work and the part not doing work. As is clear from this figure, this is caused by the development of a vortex formed at the tip of the blade 2 and the generation of a flow of wind from the pressure surface 6 of the blade 2 to the suction surface 7. The reality is that there is currently no known way to improve the flow in this area.

(Problems to be Solved by the Invention) As described above, the shape of the blades of conventional fans affects the air blowing characteristics, causing a reduction in air volume and noise.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a fan that can improve air blowing characteristics and reduce noise by improving the shape of the blades.

[Structure of the invention] (Means and effects for solving the problem) This invention has the following features:
The front end of the tip of the blade is cut out to form an outer circumferential portion having an outer diameter smaller than the maximum outer circumferential portion, the front end of this outer circumferential portion is the leading edge of the blade, the rear end of the outer circumferential portion is the maximum outer circumferential portion, The reason is that they are connected via arcuate portions to form a rectifying blade portion. This also suppresses the development of vortices created at the tip of the blade, reducing the flow from the front of the blade to the negative pressure side, improving air blowing performance.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIGS. 1 to 3, 11 is a fan used as a blower for an air conditioner, etc., and this fan 11 has a boss 12 molded from a synthetic resin material, and a boss 12 formed from a synthetic resin material.
It is composed of a plurality of blades 13 attached to the outer peripheral surface of the blade 2. These blades 13... have the same shape, so to explain one, the fan 11
It consists of a front edge 14 extending radially from the boss 12 with reference to the rotational direction of the engine, and a maximum outer peripheral portion 15 having an arcuate curvature centered on the boss 12. Furthermore, the front end of the tip portion of the blade 13 is notched,
An outer peripheral portion 16 having an outer diameter smaller than the maximum outer peripheral portion 15 is provided. The front end of this outer peripheral portion 16 is smoothly connected to the front edge 14 via a circular arc portion 17.

Furthermore, the rear end of the outer circumferential portion 16 is also smoothly connected to the maximum outer circumferential portion 15 via a circular arc portion 18. and,
A rectifying blade portion 19 is formed in an outer circumferential portion 16 having an outer diameter smaller than the maximum outer circumferential portion 15 .

Here, the outer diameter L2 of the outer peripheral portion 16 is desirably in a range of 1 to 3% of the outer diameter L1 of the maximum outer diameter portion 15.

Furthermore, the cross-sectional shape of the tip portion of the blade 13 is formed into an inclined surface 22 that slopes from the negative pressure surface 20 toward the positive pressure surface 21, as shown in FIGS.
An edge portion 23 is formed on the positive pressure surface 21 side.

When the fan 11 configured as described above is mounted on the rotating shaft of an electric motor and rotated, the air flows as shown in FIGS. 6(A) and 6(B). Here, a vortex is a turbulent flow, an arcuate arrow is a flow of wind flowing from the positive pressure surface 21 to the negative pressure surface 20, and a broken line is a boundary line between a part doing work and a part not doing work. As is clear from this figure, the part of the straightening vane 19 that is not actually working outside the broken line is smaller than before, which increases the air volume and reduces turbulence. Noise is reduced.

FIG. 7 shows the influence of the length Ll of the straightening blade section 19 on the air volume and noise, and FIG. 8 shows the influence of the length Ll of the straightening blade section 19 (LI
This shows the influence of L2)/2 on the air volume and noise, and the length L3 and width (LI L2)/2 of the rectifying blade section 19 are shown.
A range of is most desirable for increasing air volume and reducing noise. The fan has a diameter of 400.90H.

4 blades, same bell mouth 50mm height,
A diameter of 420 is used.

Note that the present invention is not limited to the above-mentioned embodiment, and may be configured as shown in FIG. 9.

That is, (A) shows an inward circular arc 18a and an outward circular arc 18b at the connection part between one straightening blade and the maximum outer peripheral portion 15.
It has been established. (B) shows one rectifying blade section provided at an angle θ from the radial direction.

Further, in the above embodiment, an axial flow propeller fan has been described, but the same effect can be obtained with a forward-sweeping blade type fan, a mixed flow type fan, or an intermediate fan between a mixed flow type and a propeller.

[Effects of the Invention] As explained above, according to the present invention, by providing the straightening vane section at the tip of the blade, the flow of air within the fan blade is improved, the air blowing characteristics are improved, and the same outer diameter is improved. This fan reduces material costs and reduces noise, making it the most effective blower for air conditioners.

[Brief explanation of the drawing]

FIG. 1 is a front view of a fan showing an embodiment of the present invention, FIG. 2 is a side view, and FIG. 3 is a perspective view of the blade, and FIG. 4 is a cross-sectional view taken along line a-a in FIG. 1. , Fig. 5 is a cross-sectional view taken along line b-b in Fig. 1, Fig. 6 (A) CB) is an explanatory diagram showing the flow of air inside the fan blade, and Fig. 7 shows the length of the rectifying blade. A graph showing the influence of L3 on the air volume and noise; Figure 8 is a graph showing the influence of the width of the rectifier blade on the air volume and noise;
9(A) and 9(B) are front views showing other embodiments of the present invention, FIGS. 10 to 13 show conventional fans, FIG. 10 is a front view of the fan, and FIG. 11 is also a side view, FIG. 12 is a perspective view of the blade, and FIG. 13 (A)
(B) is an explanatory diagram showing the flow of air within the blades of the fan. DESCRIPTION OF SYMBOLS 11... Fan, 12... Boss, 13... Blade, 14... Front edge, 15... Maximum outer circumference part, 16...
... Outer circumference part, 17.18... Arc part, 19... Rectifying blade part. Applicant's agent Patent attorney Takehiko Suzue Figure 3 (A) Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] A fan comprising a boss and a plurality of blades, in which the blades have a front edge extending radially from the boss and a tip portion continuously formed via an arc portion, with the rotation direction as a reference, the tip portion of the blade. Cut out the front end of the outer peripheral part to form an outer peripheral part having an outer diameter smaller than the maximum outer peripheral part, and connect the front end of this outer peripheral part to the front edge and the rear end to the maximum outer peripheral part through circular arc parts. A fan characterized by forming a rectifying blade section.