JPS61207898A - Electric blower - Google Patents

Abstract

PURPOSE:To cause a space part to form a muffler to perform a role of a side launch in an acoustic circuit and to enable reduction of the generation of noise, by a method wherein a space part is formed between an inner and an outer guide wall, and an opening part is formed in the outer periphery of the space part. CONSTITUTION:The guide wall of a diffuser part 26 is divided into an inner guide wall 29 and an inner guide wall 30, a space part 31 is formed between the two guide walls 29 and 30, and an outer peripheral end of a space 31 forms an opening part 32. This constitution causes the space part 31 to form a muffler and performs a role of a side launch in an acoustic circuit, and causes noise generated at the inlet of an air guide 25 to be prevented from outgoing to the outside. This enables reduction of noise of frequency. or so-called NZ noise, which is determined by a product of the number Z of blades and the number N of revolutions (rpm).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electric blower for use in a vacuum cleaner.

BACKGROUND OF THE INVENTION Conventional electric blowers of this type include, for example, the Japanese Patent Publication No. 52-4
There is one shown in Publication No. 9168.

That is, as shown in FIG. 6, an impeller 2 and an air guide 3 are provided in a casing 1, and the impeller 2 is rotated at high speed by a motor 4 to obtain air volume and vacuum pressure.

Problems to be Solved by the Invention In an electric blower having a structure in which the air guide 3 is provided on the outer periphery of the impeller 2, when the airflow discharged from the impeller 2 flows into the air guide 3, the air guide inlet The noise thought to be caused by collisions was a problem. This occurs as a product of the number of blades Z of impeller 2 and the rotation speed N (r, p, m) of impeller 2, and is commonly known as N
It is called the Z sound. Also, the efficiency of the blower varies depending on how smoothly the airflow is caused.

The present invention solves these problems by providing an improved configuration of the diffuser section of the air guide.

Means for Solving the Problems The technical means of the present invention for solving the above problems is to divide the guide wall of the diffuser part of the air guide into an inner guide wall and an outer guide wall, and to create a space between the two guide walls. A space is provided with an opening on the outer periphery of the space.

For production This technical means works as follows.

In other words, the space formed by the inner guide and outer guide wall of the air guide constitutes a muffler and serves as a side branch in the acoustic circuit, and has a structure that prevents the noise generated at the air guide entrance from being emitted to the outside. It has become.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 5. In FIG. 2, 21 is a casing containing an impeller and an air guide, which will be described later, and has an intake port 22 open in the center. Further, it is fitted and attached to the opposite side of the intake port 22 or to the motor frame 23 so as to prevent air leakage. A centrifugal impeller 24 has a plurality of blades and is driven by a motor. A diffuser portion 26 formed by a casing 21 and an air guide 26 is disposed on the outer periphery of the impeller 24 and has a passage that expands toward the outer periphery.
A return passage 28 that smoothly and independently communicates with each other to guide airflow to the motor intake hole 27 is formed at the end of the motor intake hole 27 . The air guide 26 guides the airflow sent out from the impeller 24 as described above. The guide wall of the diffuser section 26 is divided into an inner guide wall 29 and an outer guide wall 3o, and a space 31 is formed between both guide walls 29 and 30, and the outer peripheral end of this space 31 is connected to an opening 32. It has become.

Next, the operation of the configuration of this embodiment will be explained. Considering part A in Figure 1, it can be replaced with a simplified diagrammatic system as shown in Figure 3. This is known as a muffler or side branch in an acoustic circuit. Therefore, it is understood that this space portion 31 has a noise-muffling function. In particular, if the frequency at which the sound is muted is fN, then 1=c2N-1)・C/4・fN(N...1.2.3
... C... speed of sound) is given by.

As mentioned above, a particularly problematic type of noise from electric blowers is called NZ sound. The NZ sound is 5.3 in this study.
It occurs around KHz. It is also very harsh on the ears. The guide wall according to the embodiment of the present invention was provided, and as a result of the study, it was possible to reduce the NZ sound. A frequency analysis table of the embodiment is shown in FIG. 4, and a conventional one is shown in FIG. As can be seen from this figure, this example has a higher NZ sound (5.3K) than the conventional one.
Hz) and overall noise are lower. In the case of this example, e was found to be 17 lines when calculated using the above formula. After that, we conducted a study and found that l=14m. This is considered to be due to the effect that the space portion 31 has a curvature. As described above, in the embodiments of the present invention, noise reduction and efficiency improvement are sufficiently achieved.
The effect is great.

Effects of the Invention The present invention divides the guide wall of the diffuser part of the air guide into an inner and outer guide wall, and creates a space between the two guide walls to form a muffler called a side branch and reduce noise. The effect is great.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an air guide showing an embodiment of the present invention;
Fig. 2 is a partially cutaway side view of an electric blower showing an embodiment of the present invention, Fig. 3 is a side branch diagram showing the effects of the invention, and Figs. 4 and 6 are examples of the present invention. and a frequency analysis diagram of a conventional example, and FIG. 6 is a partially cutaway side view of a conventional electric blower. 21... Casing, 29... Inner guide wall, 24... Impeller, 30... Outer guide wall, 25... Air guide, 31...
... Space section, 26... Diffuser section, 32.
...Opening, 28...Return passage. Name of agent: Patent attorney Toshio Nakao and 1 other person31
1. Zuo Yanqi 3? ...Second T: J section? 5 Figure 2 27
Motor opening? 8. Performance - breath figure 3 input output

Claims (1)

[Claims] A centrifugal impeller, an air guide that guides the air flow sent out from the impeller, and a casing that encloses the impeller and the air guide, and includes an inner guide wall and an outer guide wall of the guide wall of the diffuser portion of the air guide. A space is provided between both guide walls, and the outer periphery of this space is an opening.