JPH045758Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an electric blower used in a vacuum cleaner or the like.

BACKGROUND ART Conventionally, electric blowers used in vacuum cleaners and the like have adopted a configuration as shown in, for example, Japanese Patent Publication No. 52-49168.

That is, as shown in FIG. 6, a centrifugal 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 However, in a structure in which the air guide 3 is provided on the outer periphery of the impeller 2 like the electric blower described above, when the airflow discharged from the impeller 2 flows into the air guide 3, the air guide Noise, thought to be caused by collisions at the entrance, had become a problem. This is the number of blades Z of impeller 2,
The rotation speed of impeller 2 is generated by the product of N (rpm),
It is commonly called NZ sound.

The present invention solves these problems and provides an electric blower that has a simple configuration and is highly effective in reducing noise.

Means for Solving the Problems The technical means of the present invention for solving the above-mentioned problems is to form a sound-absorbing space between the outer wall of the motor and the motor frame projecting from this in cooperation with these members. A communication port A on the upstream side is provided between the motor frame and the sound absorption space, and a communication port B on the downstream side is provided between the outer wall of the motor and the sound absorption space.

Effect This technical means acts as follows. That is, when the airflow generated by the impeller is guided into the motor, the energy of high-frequency sounds including the NZ sound is reduced due to the effect of the sound-absorbing space, and the sound pressure level is lowered.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 to 4, a centrifugal impeller 11 having a plurality of blades is attached to a shaft 13 of a motor 12, and this impeller 11 is attached to a shaft 13 of a motor 12.
An air guide 14 is disposed on the air blowing side. These impeller 11 and air guide 14 are
The motor frame 16 has an intake port 15 on the top wall, and the lower part of the circumferential wall of the motor frame 16 is surrounded by a casing 17 that is airtightly attached by press fitting.

The air guide 14 receives the air flow sent out from the impeller 11 on its upper surface, and has a plurality of differential users 18 whose passage area is gradually expanded toward the downstream side, and has a plurality of differential users 18 on its lower surface that are smoothly connected to the terminal ends of the differential users 18. A plurality of return passages 20 are formed in communication with each other to guide the airflow to the motor intake port 19 of the motor frame 16, and to guide the airflow sent out from the impeller 11 into the motor 12. In this embodiment, the side of the differential user 18 is closed and separated from the outside by a part of the casing 17, but if it is formed into a hole shape,
The differential user 18 can be formed independently of the casing 17.

By the way, the impeller 11 and the air guide 14
is configured to be larger than the diameter of the motor 12 in order to increase the fan capacity. Further, the motor frame 16 protrudes beyond the outer wall 12' of the motor, and its outer periphery is bent downward to form a corner portion 16a for press-fitting the casing 17. At the corner between the outer wall 12a of the motor and the cylindrical portion 16a of the motor frame 16 that extends from the outer wall 12a, a member 22 which together with these members 12a and 16a constitutes a sound absorption space 23 is press-fitted or tightened. It is attached by means of. This member 22 has an L-shaped cross section and an annular shape. Considering the installation work of the member 22, it is necessary to divide it into two parts and separate the outer wall 12a and the cylindrical part 16a of the motor.
It is desirable to have a structure that is press-fitted between the two. and a motor frame 16 and an outer wall 12 of the motor.
In a, there is a communication port A on the upstream side that communicates with the sound absorption space 23.
21, a communication port B25 on the downstream side is provided so that the airflow flows to the air intake port 19 and the sound absorption space 23 as shown in FIG. The sound absorption space 23 is
Although it may be a simple space, in this example, the sound absorbing material 2
3a is enclosed. Note that 24 is the outer wall 1 of the motor.
This is an exhaust port provided at 2a.

In the above configuration, the airflow sent out from the impeller 11 is decelerated in the process of flowing through the differential user 18 of the air guide 14, and its kinetic energy, that is, dynamic pressure is replaced by static pressure. The airflow flowing through the differential user 18 reaches a return passage 20, then flows through the motor 12 from the intake port 19 of the motor 12, performs a cooling effect, and is discharged from the exhaust port 24.

By the way, the airflow generates a considerable amount of high-frequency sound along the way, and the NZ sound is particularly loud.
However, in addition to being guided to the intake port 19, the airflow is also directed to the communication port A21, the sound absorption space 23, and the communication port B25.
When high-frequency sounds including NZ sound enter the sound absorption space 23 from the communication port A, these sounds expand, and when sent into the motor from the communication port B, the expansion type Due to the action of the silencer,
Harmonic sounds including NZ sound are reduced. At the same time, a phase shift occurs between the harmonic sounds including these NZ sounds accompanying the flow that does not pass through the sound-absorbing space, and the noises cancel each other out within the motor, reducing the noise. Experiments have confirmed that harsh sounds around 5.3KHz are reduced. Note that if the sound absorbing space 23 is filled with a sound absorbing material 23a, the sound absorbing effect will be further enhanced. Similar to the previous embodiment, this embodiment also aims to reduce high frequency sounds including NZ sound.

Effects of the invention As described above, according to the invention, high-frequency sound, which is a particular problem in electric blowers, is reduced by the effect of the sound-absorbing space, and noise reduction can be achieved without reducing fan efficiency. This sound absorption space is made up of the outer wall of the motor, the motor frame, and the members provided between them, and is a rational space that utilizes the space between the outer wall of the motor and the motor frame. , and its practical effects are significant.

[Brief explanation of the drawing]

Figure 1 is an enlarged sectional view of the main parts of the electric blower of the present invention.
FIG. 2 is an overall view with the same part cut away. FIG. 3 is a perspective view showing some of the constituent members, FIG. 4 is a plan view showing the relationship between the casing and the air guide, and FIG.
The figure is an exploded perspective view of a conventional electric blower. 11... Impeller, 12... Motor, 12a...
...Motor outer wall, 14...Air guide, 16...
Motor frame, 17...Casing, 21, 2
5...Sound absorption port, 22...Sound absorption space member, 23...
...Sound absorbing space.

Claims (1)

[Claims for Utility Model Registration] (1) A centrifugal impeller driven by a motor, an air guide having a passage that guides the air flow sent out by the impeller from the outer periphery of the impeller to the motor, and covering these impeller and air guide. A casing is airtightly attached to the motor frame, and between the outer wall of the motor and the motor frame projecting from the motor frame, there is provided a member that together with these members constitutes a sound-absorbing space, and the motor frame and the sound-absorbing space are separated. An electric blower with a communication port A on the upstream side in between, and a communication port B on the downstream side between the outer wall of the motor and the sound absorption space. (2) The electric blower according to claim 1 of the utility model registration claim, in which a sound-absorbing material is provided in the sound-absorbing space.