JPH0261398A - Axial flow fan - Google Patents

Abstract

PURPOSE:To improve the tone color by dispersing the order component of the noise frequency by installing the first fan blade and the second fan blade each of which has different outer shape and workload, alternately in an unequal pitch onto a rotary boss. CONSTITUTION:The first and second fan blades 12 and 14 are installed alternately at an unequal pitch onto the periphery of the rotary boss part 10 of an axial flow fan. The both fans blades 12 and 14 are set so that the planery shape differs and also the workload differs. For example, if the size of the planary shape of the first fan blade 12 is 1, and the workload is 1 as a standard workload, the size of the planary shape of the second fan blade 14 is set to 0.9-0.94 and the workload is set to 0.6-0.7. Further, the pitch is set at 108 deg. between the first and second fan blades, and set at 72 deg. between the second and first fan blades. Therefore, the tone color can be improved by dispersing the order component of the noise frequency, and the generation of the rasping noise can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an axial flow fan, and particularly to an axial flow fan suitable for reducing noise by using blades having different specifications.

[Conventional technology]

In vehicles such as automobiles, axial fans are used as devices for cooling, for example, radiators for engine cooling or condensers for cooling air conditioners.

Conventionally, this type of axial fan has been developed, for example, in
As disclosed in Japanese Patent Publication No. 508 and Japanese Patent Application Laid-Open No. 54-32808, a plurality of fan blades are fixed to a rotating boss portion attached to a rotating shaft of an engine or a motor.

[Problem to be solved by the invention]

However, in conventional axial fans, the arrangement pitch of each fan blade is unequal in order to reduce the noise level, but as shown in Fig. 3, when the axial fan rotates, There has been a problem in that harsh noise is generated that contains many specific frequency components of n-order components such as the first-order component and the second-order component of rotation.

The present invention has been made to solve these conventional problems, and its purpose is to provide an axial flow fan that can disperse the frequency components of noise into n-order components of the blades.

[Means for Solving the Problems] An axial fan according to the present invention is an axial fan in which a plurality of fan blades are fixed to a rotary boss portion, and a first fan having a standard workload and a standard external shape. Two fan blades and two second fan blades whose workload and external shape are smaller than the standard workload and external shape are arranged alternately, and
The mounting pitch interval between the fan blade and the second fan blade is different.

[For production]

In the present invention, since the first fan blades and the second fan blades, which have different workloads and outer shapes, are installed alternately at unequal pitches, when each fan blade rotates, there is a difference between each fan blade. Interference between the blade rows is prevented, and the order components of the rotation are dispersed into the order components of the blades, making it possible to improve the timbre of the noise to make it easier to hear, and suppressing the harsh sound generated by the rotation of the axial fan. becomes possible.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an axial flow fan according to an embodiment of the present invention, and in the figure, 10 is a rotating boss portion.

Around this rotating boss 10, two first fan blades 12 and two second fan blades 14 are arranged alternately.
Moreover, they are attached at unequal pitches.

Each first fan blade 12 and each second fan blade 14
are configured to have different planar shapes and different amounts of work.

In this embodiment, assuming that the planar size of the first fan blade 12 is 1 (reference external shape), the planar size of the second fan blade 14 is set to 0.9 to 0.94. . For example, the outer diameter of the first fan blade 12 is 32 mm.
0φ, and the outer diameter of the second fan blade 14 was set to 290φ. Further, assuming that the amount of work of the first fan blade 12 is 1 as the standard amount of work, the amount of work of the second fan blade 14 is set to 0.6 to 0.7 of the standard amount of work.

For example, the amount of work of the first fan blade 12 is 5.4rr.
r/min, the amount of work of the second fan blade 14 is set to 3.6 m/ll1in. The amount of work performed by the first fan blade 12 and the second fan blade 14 arranged in this way is 10.
8rrf/min, and the second fan blade 14 has a speed of 7.2rd/min.

Also, among each of the first fan blades 12 and each of the second fan blades 14, one of the first fan blades 12 and one of the second fan blades
The pitch between the fan blades 14 and the fan blades 14 is set to approximately 10 degrees, and the pitch between the second fan blade 14 on one side and the first fan blade 12 on the other side is set at a pitch interval of approximately 72 degrees.

When the axial flow fan 16 with the above configuration was rotated and the noise level was measured, as shown in FIG.
High-order components such as the next component and the 100th order component are generated, and the frequency components of the entire noise level are dispersed and flattened to improve the tone, and the rotation of the axial fan 16 generates a harsh sound. It was confirmed that it suppresses

Furthermore, when comparing the noise level produced by the axial fan 16 according to this embodiment at the same air volume with the noise level produced by the conventional axial fan shown in FIG. 3, the noise level was also 2.4.
It was confirmed that the reduction was more than dB.

〔Effect of the invention〕

As explained above, according to the present invention, the blades having different external shapes and workloads are attached to the rotating boss at unequal pitches to disperse the order components of the noise frequency and improve the tone. Even if noise is generated by the rotation of the flow fan, it is possible to suppress generation of harsh sounds.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an axial fan according to an embodiment of the present invention. FIG. 2 is a characteristic diagram of the noise level of an axial fan according to an embodiment of the present invention. FIG. 3 is a characteristic diagram of the noise level of a conventional axial fan. [Description of symbols of main parts] 10... Rotating boss portion 12... First fan blade 14... Second fan blade 16... Axial flow fan. Patent applicant Calsonic Corporation

Claims (1)

[Claims] (1) In an axial flow fan in which a plurality of fan blades are fixed to a rotating boss part, a first fan blade having a standard amount of work and a standard external shape, and a first fan blade having a standard amount of work and a standard external shape, and a standard workload and external shape. An axial flow fan characterized in that two smaller second fan blades are arranged alternately, and the mounting pitch intervals of the first fan blade and the second fan blade are different.