JPS6140492A - Blower - Google Patents

Abstract

PURPOSE:To reduce a vane sound, by making a tongue part movable so as to cause a distance between the tongue part of a casing of a crossflow fan and an outer circumferential surface of an impelller to be irregularly changed according to rotation of the impeller. CONSTITUTION:A tongue part 1 is constituted of a movable part 1a and a fixed part 1b. The movable part is provided with a lot of irregular jogs and made free of rotation around the center 1c. With the movable part 1a rotated, a distance between a tongue part 1a and an outer circumferential surface 4a of an impeller 4 is irregularly alterable. Accordingly, a cascade interfering state between an impeller vane and the tongue part becomes irregular in a timing manner, and pressure in and around the tongue part also irregularly varies so that a vane sound is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a blower that reduces blowing noise, particularly noise caused by interference between the blades and the casing tongue.

Conventional structure and its problems A conventional blower of this type was constructed as shown in FIG. That is, in a blower in which an impeller 4 is disposed in a casing 3 formed by the tongue part 1 and the rear guider 2 (t'4), and a blowing action is performed by rotating the impeller in the direction of arrow a, the tongue part 1 and the rear guider 2 are connected to each other. The distance ε from the outer circumferential surface 4a of the &l vehicle 4 was fixed.

It has been found that as the distance ε becomes narrower, the blower performance improves, but on the other hand, the blower noise, especially the noise caused by the interference between the blades and the tongue, becomes louder.

For this reason, the conventional design method has been to set an appropriate ε at the expense of either noise or air blowing performance, and it has not been possible to design a blower that satisfies both air blowing and noise performance at the same time. .

OBJECT OF THE INVENTION The present invention eliminates such conventional drawbacks by irregularly changing the distance between the tongue and the outer surface of the impeller during rotation of the impeller, thereby reducing interference between the blade row and the tongue. The purpose is to lower the frequency of the feathers that occur.

Structure of the Invention In order to achieve this object, the present invention provides a blower composed of a casing and an impeller, in which the distance between the tongue of the casing and the outer peripheral surface of the impeller is irregular in accordance with the rotation of the impeller. The tongue or a part thereof is movable so as to change the tongue.

With this configuration, the distance between the tongue and the outer peripheral surface of the impeller changes irregularly while the impeller is rotating.

Therefore, the state of interference between the impeller blade row and the tongue becomes irregular in time, and as a result, the pressure near the tongue also changes irregularly, so the specific frequency f determined by the number of blades Z and the rotation speed n [rpm] □ It is possible to reduce the sound of the blades at [Hz] to a low frequency range.

f()=n-Z/60 Description of Embodiment An embodiment of the present invention will be described below with reference to the drawing of FIG. In FIG. 2, the same parts as in FIG. 1 are given the same numbers.

In the figure, the tongue portion 1 is made up of a movable portion 1a and a fixed portion 1b, and the movable portion can rotate around a center 1C over a large number of irregular irregularities.

Then, when rotating the impeller to perform the blowing action,
By simultaneously rotating the movable part 1a, the tongue part 1
The distance between a and the outer peripheral surface 4a of the impeller 4 can be changed irregularly. As a result, the state of interference between the impeller blades and the tongue becomes irregular over time, and the pressure near the tongue changes irregularly, so that the blade noise can be reduced.

Here, we have described a case in which the movable part 1a is forcibly rotated using an external drive source (not shown), but the movable part uses the circulating flow 6 of the vortex 5 generated near the tongue part. A similar effect can be expected even if the device is rotated.

Effects of the Invention As described above, according to the blower according to the present invention, the tongue portion or a portion thereof is arranged such that the distance between the tongue portion of the casing and the outer peripheral surface of the impeller changes irregularly in accordance with the rotation of the impeller. Since the tongue part is movable, it is possible to reduce blade noise caused by interference between the impeller blade row and the tongue part, which is noticeable when the tongue part is fixed.

Therefore, the distance between the tongue and the outer periphery of the impeller can be narrowed to the extent that the noise level is reduced compared to a conventional blower with a fixed tongue, making it possible to improve the air blowing performance. It is.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional blower, and FIG. 2 is a cross-sectional view of a blower according to an embodiment of the present invention. 1... Tongue, 1a... Tongue movable part, 1
b0090. , tongue fixing part, 2... rear guider, 3... casing, 4... impeller. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
figure

Claims (1)

[Claims] It is composed of a casing and an impeller, and the tongue or a part thereof is movable so as to irregularly change the distance between the tongue of the casing and the outer peripheral surface of the impeller in accordance with the rotation of the impeller. blower.