JPH0788838B2 - Electric blower - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric blower used in a vacuum type vacuum cleaner.

2. Description of the Related Art Conventionally, this type of electric blower has a structure as shown in FIGS. 6 and 7. A centrifugal impeller 5 is provided in a casing 4 on a rotating shaft 3 of a motor 2 whose both ends are supported by ball bearings 1. Then, the rotation of the centrifugal impeller 5 sucks in air from the intake hole 6 provided in the casing 4, and the airflow of the arrow sent from the centrifugal impeller 5 is installed by the air guide 8 having the return passage 7. 2 to the intake hole 9 of the motor 2 and the exhaust hole 10 of the motor 2
It was supposed to be discharged more.

However, in such a structure, since the motor 2 rotates at a high speed (20000 rpm to 30000 rpm), the vibration caused by the unbalance of the centrifugal impeller 5 and the bearing of the bearing 1 is caused. Is generated, vibration is transmitted to the main body of the vacuum cleaner when it is incorporated into the main body of the cleaner, which causes unpleasant noise, which is a serious problem.

Among them, the vibration caused by the imbalance means that the vibration frequency is equal to or higher than the rotation speed, and the first cause is the imbalance of the rotating body including the centrifugal impeller 5, that is, the imbalance. Is. Second, there is uneven rigidity of the support system for these rotating bodies. That is, when the unbalanced rotating body rotates, the rotating body swirls and generates vibration. At this time, if the rigidity of the rotating body support system varies depending on the direction (for example, when the rigidity is weak only in the lateral direction), whirling vibration is increased. Such a phenomenon becomes more prominent as the number of rotations increases and approaches the resonance frequency of the rotation support system, and the effect of uneven rigidity of the rotation body support system is strongly exerted on unbalanced vibration.

The present invention solves the above-mentioned problems of the conventional technique, and provides an electric blower that reduces rotational vibration and generates less noise.

Means for Solving the Problems The technical means of the present invention for solving the above problems is a rotor having a rotary shaft whose both ends are supported by an intake side bracket and an exhaust side bracket by bearings, and is press-fitted and fixed to a motor frame. Fixed stator, a plurality of intake holes of substantially the same shape provided on the intake side bracket, a plurality of exhaust holes of the same shape provided on the exhaust side bracket or the motor frame, and a centrifugal unit fixed to the rotating shaft. Type impeller, an air guide arranged outside the centrifugal type impeller, and a casing containing the air guide and the centrifugal type impeller. The number of exhaust holes, the number of intake holes, and the number of stator press-fitting points In between 1
Other than the common divisor, and the above numbers are not equal.

Action The action of this technical means is as follows.

That is, in general, when there are common divisors other than 1 between the numbers of the intake holes, the exhaust holes, and the press-fitting positions of the stator, for example, when these numbers are 4, 4, 2, the rotation shaft support system The stiffness (rigidity) is 2 during one rotation when viewed from the rotation axis.
It changes cyclically. When the rotation speed becomes high and approaches the resonance frequency of the rotary shaft support system, the rate of change of this rigidity becomes large. This change in rigidity increases vibrations due to the imbalance of the impeller. However, in the present invention, since there is no common divisor other than 1 in the number of press-fitting positions of the intake hole, the exhaust hole, and the stator, the rigidity of the rotary shaft support system as viewed from the rotary shaft is made uniform, and the impeller The vibration due to the imbalance does not increase, and the harmonic component becomes small.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 denotes a motor, an exhaust side bracket 11 formed integrally with a motor frame, a stator 12 press-fitted and fixed to the exhaust side bracket 11, and an intake side bracket 1.
3. The rotor 15 is fixed to the rotary shaft 14. Both ends of the rotor 15 are supported by both brackets 11 and 13 by ball bearings 16 so as to maintain a minute gap between the rotor 15 and the stator 12. A centrifugal impeller 18 having a plurality of blades 17 is fixed to the rotating shaft 14. Reference numeral 19 denotes an air guide, which is mounted on the intake side bracket 13. Reference numeral 20 denotes a casing, which includes the centrifugal impeller 18 and the air guide 19, and is fixed to the outer periphery of the intake side bracket 13,
A blower intake hole 21 is provided in the center.

The intake side bracket 13 is provided with five motor intake holes 22 as shown in FIG. The stator 12 has four press-fitting points 23, as shown in FIG. Fourth
As shown in the figure, there are three motor exhaust holes 24 provided in the exhaust side bracket 11.

Next, the operation of the above-described embodiment will be described.

By driving the motor 10, the centrifugal impeller 18 rotates at a high speed (about 30,000 rpm), sucks air from the blower intake hole 21, and the air guide 19 sends out the air. Then, the airflow is gradually reduced by the air guide 19 and flows into the motor intake hole 22, passes through the inside of the motor 10, and is exhausted by the motor exhaust hole 24. When the motor 10 rotates at a high speed in this way, the frequency of vibration caused by the rotational imbalance increases and approaches the resonance frequency of the rotary shaft support system. The rotating shaft support system has a stator mass of Ms25, a rotor mass of Mr26,
If the radial rigidity of both brackets 11 and 13 is K27, it can be approximated to a vibration system as shown in FIG. When the motor 10 is rotating at a rotation speed sufficiently lower than the resonance frequency of this vibration system, the stator mass Ms25 and the rotor mass Mr26 vibrate together. That is, the radial rigidity K27 of both brackets is hardly deformed. However, when the rotational speed increases and approaches the resonance frequency of the vibration system, the radial rigidity K27 of the brackets 11 and 13 gradually bends. The radial rigidity K27 of both brackets is determined by the motor intake hole 22 and the motor exhaust hole.
There are 24 so it is not uniform. That is, the radial rigidity K27 changes depending on the direction. Similarly, the press-fitting point 2 of the stator 12
Directionality appears in rigidity K27 also for 3. The direction of the force component of the vibration caused by the rotational unbalance is determined by the position of the unbalance. Therefore, while the rotor 15 makes one rotation, the direction in which the vibration force acts also makes one rotation. As described above, since the radial rigidity K27 of both brackets 11 and 13 is directional, the rigidity K27 periodically changes during one rotation of the rotor 15. That is, K27 in FIG. 5 is not constant but changes periodically. As a result, vibrations, especially harmonic components, increase.

Therefore, in this embodiment, the numbers of the motor intake holes 22, the motor exhaust holes 24, and the press-fitting points 23 of the stator 15 are 5, 4, and 3, respectively.
Since there is no common divisor other than 1 and 1, the radial rigidity K27 of both brackets 11 and 13 changes with the rotor 15
5 times as the influence of the motor intake hole 22 while
The influence of the motor exhaust hole 24 is three times, and the influence of the press-fitted portion of the stator 12 is four times.

As described above, since the influences of the respective factors on the change in the rigidity K27 are different, as a result, the change in the rigidity K27 in the radial direction is made uniform. Therefore, the distortion of the vibration due to the rotational imbalance becomes small, and the vibration, especially the high frequency component becomes small.

In addition, motor intake hole 22, motor exhaust hole 24, stator press-fitting point
There are many combinations of the number of 23 other than this embodiment.

As described above, the present invention does not have a common divisor other than 1 between the number of motor exhaust holes, the number of motor intake holes, and the number of stator press-fitting points, and the numbers are not equal. Since the radial rigidity of the intake side and exhaust side brackets of the motor has been made uniform, an increase in vibration due to rotational imbalance is prevented, and its harmonic components are reduced to reduce the noise and vibration of the electric blower. It has a great effect on reduction.

[Brief description of drawings]

FIG. 1 is a side sectional view of an electric blower according to an embodiment of the present invention, FIG. 2 is a plan view of a motor showing a position of a motor intake hole of the electric blower, and FIG. 3 is a press-fitting position of the motor stator. Fig. 4 is a plan sectional view of the motor, Fig. 4 is a plan sectional view of the motor showing the position of the motor exhaust hole, Fig. 5 is a model diagram showing a rotor support system, and Fig. 6 is a side sectional view showing a conventional electric blower. FIG. 7 and FIG. 7 are plan views of the motor showing the positions of the motor intake holes. 11 …… Exhaust side bracket, 12 …… Stator, 13 …… Intake side bracket, 14 …… Rotating shaft, 15 …… Rotor, 18 …… Centrifugal impeller, 19 …… Air guide, 20 …… Casing, twenty two
...... Motor intake hole, 23 ...... Stator press-fitting point, 24 ...... Motor exhaust hole.

Claims (1)

[Claims] 1. A rotor having a rotary shaft whose both ends are supported by an intake side bracket and an exhaust side bracket by bearings, a stator press-fitted and fixed to a motor frame, and a rotor provided on the intake side bracket. A plurality of shaped motor intake holes, a plurality of identical shaped motor exhaust holes provided on the exhaust side bracket or motor frame, a centrifugal impeller fixed to the rotary shaft, and arranged outside the centrifugal impeller. It has an air guide and a casing containing this air guide and a centrifugal impeller, and is 1 between the number of motor exhaust holes, the number of motor intake holes, and the number of stator press-fitting points.
An electric blower that does not have a common divisor other than, and has a relationship in which those numbers are not equal.