JPS61252896A - Motor driven blower - Google Patents

Abstract

PURPOSE:To reduce noise by projecting a portion of a side wall of an air guide return passage provided with a motor driven blower into a motor along motor communicating holes. CONSTITUTION:An air guide 20 is placed on a bracket 14 of a motor and the air guide 20 is provided with a return passage 22 for introducing air flow supplied from a centrifugal impeller 19 to communicating holes 21. A portion of a side wall 23 of the return passage 22 extends into the motor 10 along the communicating holes 21 of the motor 10. As a result, the air flow is introduced into a space between a frame 11 and a fixed member 12 along the side wall, which prevents a vortex to be produced and reduces noise.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an electric blower used in a vacuum cleaner or the like.

2. Description of the Related Art Conventionally, this type of electric blower has a structure as shown in FIG. That is, it is fixed to the rotating shaft 1 of the electric motor 6,
A centrifugal impeller 2 provided in the casing 7 sucks air through the intake hole 8 of the casing 7, and the air flow sent out from the impeller 2 is guided to the communication hole 6 of the electric motor 5 by installing an air guide 4 having a return passage 3. , and was designed to be discharged from an exhaust hole 9 of the electric motor 5.

Problems to be Solved by the Invention However, with such a structure, since the centrifugal impeller 2 rotates at high speed (20,000 to 30,000 Or, p, m), noise is generated due to multiple factors. Reduction has been a major issue for this type of electric blower.

One of the causes of noise generation is that the airflow sent out by the centrifugal impeller 2 is guided through the return passage 3 of the air guide 4 to the communication hole 6 of the electric motor 6, and when flowing into the motor, the airflow passes through the communication hole 6. Immediately after the passage, the flow path expands rapidly, creating a vortex as shown by the arrow, which is a contributing factor to noise generation. Also, this type of noise has a relatively low frequency (,1(K
Hz), so it is difficult to take soundproofing measures when incorporated into the vacuum cleaner body, and this is a major problem among electric blower noises.

Means for Solving the Problems The technical means of the present invention for solving the above problems is to make a part of the side wall of the return passage of the air guide protrude into the inside of the motor along the communication hole of the motor.

action The effect of this technical means is as follows.

In other words, when the airflow sent out by the centrifugal impeller is guided to the communication hole of the air guide motor that has a return passage and flows into the electric motor through the communication hole, a part of the side wall of the return passage passes through the communication hole. Since the airflow extends along this side wall to the inside of the motor, the airflow flows into the inside of the motor along this side wall, and the generation of vortices is suppressed without rapid expansion.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings. In FIG. 1, reference numeral 10 denotes an electric motor, which includes a stator 12 fixed in a frame 11 and a bearing provided in a bracket 14 and the frame 11 so as to maintain a minute gap 13 between the stator 12 and the stator 12. The rotor 16 is supported by a rotor 15. Rotation shaft 17 of rotor 16
The centrifugal impeller 1 has a plurality of blades 18.
9 is fixed. 2o is an air guide placed on the bracket 14 of the electric motor. The air guide 2o connects the airflow sent out from the centrifugal impeller 19 to the electric motor 1.
A return passage 22 is provided for leading to the communication hole 21 provided in the electric motor 1o, and a part of the side wall 23 of this return passage 22 extends into the electric motor 1o along the communication hole 21 of the electric motor 1o. 24 is a casing, a centrifugal impeller 19,
It includes an air guide 20 and is fixed to the outer periphery of the bracket 14. Reference numeral 26 indicates an intake hole provided in the air guide 2o, and reference numeral 26 indicates an exhaust hole provided in the frame 11 of the electric motor 10. FIG. 2 shows the return passage 22 of the air guide 2°, and the side wall 23 of the return passage 22 in the shaded area projects into the electric motor 10.

Figure 3 shows the communication hole 2 provided in the bracket 14 of the electric motor.
1, and a part of the side wall 23 of the return passage shown in FIG. 2 is fitted into the position shown by the dashed line.

Next, the operation of the configuration of this embodiment will be explained. By driving the electric motor 1o, the centrifugal impeller 19 rotates at a high speed of 20,000-30,000 r, p, m), sucks air through the intake hole 25, and sends it out from the outer periphery of the impeller 19. The emitted airflow is gradually expanded by the volute part 27 of the air guide 20 and returns to the return passage 22.
, and is guided into the motor through the communication hole 21 along the side wall of the return passageway that protrudes into the motor 1o. After that, the airflow flows through the gap 2 between the frame 11 and the stator 12 as shown by the arrow.
8 and is exhausted from the exhaust hole 26. Airflow return passage 2
24 through the communication hole 21 into the inside of the motor 1o, in the conventional configuration, the flow path expands rapidly and generates a vortex, which generates noise of 1 (KHz) or less, but this example In the configuration, the side wall 23 of the return passage 22
extends close to the stator 12 inside the motor 1o, so the airflow is guided to the gap between the frame 11 and the stator 12 while following this side wall 23 as shown by the arrow, thereby suppressing the generation of eddies. As a result, the frequency is mainly 1 (KHz
) The following noise is reduced and flow path loss is also reduced, greatly contributing to improving efficiency.

Effects of the Invention In the present invention, a part of the side wall of the air guide return passage protrudes into the inside of the electric motor along the communication hole. The generation of swirling currents can be minimized, noise mainly below 1 (KHz) can be reduced, and flow path loss is also reduced, which is useful for improving efficiency.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of an electric blower according to an embodiment of the present invention;
Figure 2 shows the air guide of the electric blower, with person showing its front view, B its bottom view, and Figure 3 showing the electric motor of the same electric blower, A being its top view, B its front view, and Figure 3 showing the motor of the same electric blower. FIG. 4 is a partial sectional view showing a conventional electric blower. 17...Rotating shaft, 19...Centrifugal impeller, 21...Communication hole, 22...Return passage, 20...Air guide , 24...
Casing, 23...Side wall. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] The motor has a centrifugal impeller fixed to the motor rotating shaft, an air guide having a return passage that guides the air flow sent out from the impeller from the outer periphery of the impeller to the motor communication hole, and a casing containing the impeller and the air guide. An electric blower in which a part of the return passage side wall of the air guide protrudes into the motor along the motor communication hole.