JPH0639958B2 - Electric blower - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric blower, and particularly to an electric blower suitable for an electric vacuum cleaner.

[Prior Art] In an electric blower, the air pressure between the fixed guide vanes and the back surface of the centrifugal impeller pushes air toward the outer peripheral direction due to the frictional effect of the back surface of the centrifugal impeller, and the centrifugal impeller side of the fixed guide vanes and the motor side. The pressure difference between the two causes a circulating flow.

In order to prevent this circulating flow, JP-A-55-69797
As described in Japanese Patent Publication No. JP-A-2003-264, there has been proposed a technique for press-fitting the inner peripheral cylindrical portion of the fixed guide vane and the outer peripheral surface of the bearing support portion of the end bracket of the motor to prevent a circulating flow generated therebetween. .

[Problems to be solved by the invention]

However, the air pressure difference between the centrifugal impeller side of the fixed guide vane and the motor side is large because the air is pushed out in the outer peripheral direction due to the frictional effect of the back surface of the centrifugal impeller, and the air pressure difference becomes larger toward the inner circumferential side of the centrifugal impeller. In the technique described in Japanese Patent Laid-Open No. 55-69797, there is a drawback that the circulating flow cannot be easily prevented because the airtightness is to be obtained at the place where the pressure difference is large.

In addition, the fixed guide vanes are often integrally molded of thermoplastic resin, and the fixed guide vanes receive a force in the direction toward the centrifugal impeller side due to the heat from the motor side and the agitating heat of the air flow, causing thermal deformation. Therefore, there is a possibility of contacting the centrifugal impeller and inhibiting rotation.

Therefore, an object of the present invention is to solve the above problems, and to provide an electric blower that prevents a circulating flow and prevents thermal deformation of fixed guide vanes.

[Means for solving problems]

In order to achieve the above object, a feature of the present invention is that an air hole is provided on an outer peripheral side surface of an end bracket, and an inner peripheral portion of a fixed guide vane that guides air from the air hole to an outer peripheral surface of the end bracket. It is to fit airtightly to the side surface.

[Action]

According to the present invention, since the inner peripheral portion of the fixed guide vane and the outer peripheral side surface of the end bracket are airtightly fitted to each other on the outer peripheral portion of the end bracket having a small pressure difference, the circulating flow can be easily prevented. It is possible to prevent the thermal deformation of the fixed guide vane.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
The figure is a vertical cross-sectional view showing an example applied to an electric blower used for an electric vacuum cleaner or the like.

The motor 1 is composed of a housing 2 and an end bracket 3, and an inner circumference of a fixing plate 4 is fitted and fixed to an outer circumference of the end bracket 3. An air hole 20 is provided on the outer peripheral surface of the end bracket 3, and the inner periphery 21 of the fixed guide vane 7 made of synthetic resin is press-fitted to the outer periphery of the end bracket 3 so that the fitting portion is airtight. ing. In the axial direction of the end bracket 3, the centrifugal impeller 6 is fastened and fixed to the rotating shaft 8 with a screw 9. The casing 5 covers the centrifugal impeller 6 and the fixed guide blade 7, and is fitted and fixed to the outer periphery of the fixed plate 4. At this time, the fixed guide blade 7 is sandwiched and fixed between the inner peripheral bottom surface of the casing 5 and the flat surface portion of the fixed plate 4.

The airflow generated by the rotation of the centrifugal impeller 6 exits from the centrifugal impeller 6 as shown by the arrow in FIG.
After passing through the flow path formed by the differential user 7a, the return guide vane 30 on the rear surface, and the casing 5, the air flows into the motor 1 through the air holes 20 of the end bracket 3 to cool the inside of the motor. At this time, in the space 50 between the fixed guide vane 7 and the end bracket 3 and the centrifugal impeller 6, air is pushed out to the outer periphery by the friction with the back surface of the rotating centrifugal impeller 6 and the centrifugal force, and the space 50 becomes negative pressure,
The air pressure decreases toward the inner circumference. In addition, since positive pressure is generated in the return flow passage 55 formed on the return guide vane 30 side of the fixed guide vane 7, a differential pressure is applied to the fitting portion between the inner circumference 21 of the fixed guide vane 7 and the outer circumference of the end bracket 3. Will occur.

However, since the fitting portion is located near the outer periphery of the centrifugal impeller 6, the fitting portion portion in the space 50 has a small pressure drop and a small pressure difference from the return flow passage 55, Easy to keep the fitting part airtight. Therefore, it is possible to prevent the circulating flow, eliminate the loss due to the circulating flow without requiring airtightness due to the strong press-fitting, and improve the blowing efficiency.

Here, the fitting method of the inner circumference 21 of the fixed guide vane 7 and the outer circumference of the end bracket 3 may be a method such as press fitting or bonding, but since the pressure difference in the fitting portion is small, only a light press fitting is used. It can be airtight and prevent the circulating flow. In this case, as shown in FIG. 3, it suffices to assemble linearly only in the axial direction, and the assembly can be facilitated.

Further, in the past, the structure was such that the inner circumference 21 of the fixed guide blade 7 and the outer circumference of the bearing support portion 25 of the end bracket 3 were fitted, but in this case, the flat portion 22 of the fixed guide blade 7 in the radial direction. The length was getting longer. For this reason, the influence of heat from the motor 1 and heat generation due to agitation of the air flow are easily received,
This deforms and contacts the back of the rotating centrifugal impeller,
There is a risk that the motor may be agitated and that the stationary guide vanes 7 and the centrifugal impeller 6 may be damaged. On the other hand, by adopting a structure in which the inner circumference 21 of the fixed guide vane 7 is fitted to the outer circumference of the end bracket 3, the radial length of the flat plate portion 22 can be shortened, and thus the heat from the motor is reduced. Hard to receive and hard to deform. Further, since the length of the flat plate portion 22 facing the back surface of the centrifugal impeller 6 is shortened, the flat plate portion 22 is hard to be deformed, and even if it is deformed, contact with the back surface of the centrifugal impeller 6 is unlikely to occur.

When the inner circumference 21 of the fixed guide vane 7 and the outer circumference of the end bracket 3 are fitted together, the flow passage configuration is such that the dynamic pressure of the air flow emitted from the centrifugal impeller 7 is kept in the flow passage formed by the differential user 7a. The pressure is converted and repeated on the outer peripheral portion, and is introduced into the motor 1 through the air holes 20 of the end bracket 3 through the return passage 55 formed by the return guide vane 30. The larger the flow passage cross-sectional area, the smaller the loss of the return flow passage. However, since the return flow passage is provided on the end face of the end bracket 3 on the side of the centrifugal impeller 6 in the related art, the return flow passage cross-sectional area is reduced. However, if the size of the blower is increased, the length in the axial direction becomes longer, and the blower section must be enlarged. In this embodiment, since the return flow passage is formed on the outer peripheral portion of the end bracket 3, the return flow passage cross-sectional area can be increased without increasing the size of the electric blower. After the folded-back portion 7b from the differential user 7a to the return flow passage 55 is folded back as a smooth inclined surface as shown in FIG. 3, the ventilation loss can be reduced by increasing the flow passage cross-section unless turbulent flow is generated.
It is desirable that the height ratio between the differential user 7a and the return guide vane 30 be 1: 1.5 or more. Further, the height of the return guide vane 30 is as shown in FIG.
Only the blade 30a at the position where 0 is partitioned divides each flow path so that the blade 30a abuts the fixed plate 4. Reference numeral 30c is a rib that is in close contact with the outer peripheral surface of the end bracket 3 to provide airtightness between the channels. 40 is a positioning boss that fits into a hole provided in the fixed plate 4. The number of blades 30b having a small height between the blades 30a is set to correspond to the number of flow paths formed by the blades of the differential user 7a, and the continuous flow path is provided from the differential user 7a to the folded-back portion 7b so that the flow is disturbed. Is being prevented. After folding back, it is desirable to increase the cross-sectional area of the flow path as described above, rather than to raise the blade 30b to divide the flow path into smaller pieces, and to join the large flow path to increase the cross-sectional area as in this embodiment. However, the effect of loss reduction can be obtained. The effect is particularly great in the large air volume range.

On the other hand, the number of blades of the diff user 7a is often determined in view of aerodynamic performance and noise, and the return guide 30
Since the selection is made regardless of the number of blades 30a corresponding to the number of the air holes 20 on the side, the ratio of the number of blades of the Diff user 7a to the number of blades 30a does not always become an integral multiple.

Even in this case, in the present embodiment, even if an unequal number of blades 30b are arranged between the blades 30a as shown in FIG. 4, they are eventually merged into a large flow passage so that the inflow condition from each flow passage is made uniform. Can be converted. The height of the blade 30b is preferably 1/2 or less of that of the blade 30a.

In addition, since the number of high-height blades 30a can be reduced, there is no problem that the mold is stuck in the mold and the mold release is deteriorated during molding by the mold.

〔The invention's effect〕

 According to the present invention, the following effects can be obtained.

(1) Since the inner circumference 21 of the fixed guide vane 7 is fitted to the outer circumference of the end bracket 3 where the pressure difference between the space 50 on the centrifugal impeller 6 side and the return flow passage 55 is small, airtightness can be easily obtained and the circulation flow can be improved. Can be prevented and the blowing efficiency can be improved.

(2) Since the inner circumference 21 of the fixed guide vane 7 and the outer circumference of the end bracket 3 are easily airtight, no special assembly such as adhesion or welding is required to achieve airtightness, and only press fitting is required. It is airtight and easy to assemble.

(3) Since the radial length of the flat plate portion 22 of the fixed guide vane 7 can be shortened and the heat from the motor is not easily received, the flat plate portion 2
2 is not easily deformed, and the flat plate portion 22 comes into contact with the bottom and back surfaces of the centrifugal impeller 6, and there is no possibility that the motor will be agitated or the centrifugal impeller 6 and the fixed guide blade 7 will be damaged.

(4) Since the air holes 20 are provided on the outer peripheral surface of the end bracket 3, the return flow passage 55 formed by the return guide vanes 30 is formed on the outer circumference of the end bracket 3. As a result, the axial dimension of the blower unit can be shortened, and the electric blower can be downsized. Moreover, the return flow passage cross-sectional area can be increased without increasing the size of the electric blower, the ventilation loss in the return flow passage 55 can be reduced, and the blow efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention, FIG. 2 is a partial sectional view of the embodiment, and FIG. 3 is a perspective view showing an assembly of a fixed guide vane and a motor. FIG. 5 is a plan view of the fixed guide vane on the return guide vane side, FIG. 5 is an exploded perspective view showing the assembly of the motor and the blower, and FIG. 6 is a perspective view showing the appearance of one embodiment. 1 ... Motor, 3 ... End bracket, 4 ... Fixing plate, 5 ...
Casing, 6 ... Centrifugal impeller, 7 ... Fixed guide vane, 7a
... Diff user, 20 ... Air vent, 21 ... Inner circumference, 30 ... Return guide vane.

Claims (1)

[Claims] 1. A motor, an end bracket of the motor, a centrifugal impeller provided in the axial direction of the end bracket, an air hole provided on an outer peripheral side surface of the end bracket, and the motor from the air hole. A fixed guide vane that guides the wind into the inside and a casing that covers the centrifugal impeller and the fixed guide vane are provided, and the inner peripheral portion of the fixed guide vane is airtightly fitted to the outer peripheral side surface of the end bracket. Electric blower characterized by the following.