JPH0578675B2 - - Google Patents

Description

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

Conventional structure and problems thereof Conventionally, in this type of electric blower, as shown in FIG. The air guide 2 is integrated with the impeller 1 and the air guide 2.
It consists of a casing 4 provided to cover the casing 4. The casing 4 presses the upper end of the differential user section and is attached to the motor bracket upper 3 by press fitting or the like.

5 is an inlet of the casing 4, from which the air flow is sucked. 6 is a motor shaft. 7 is a blade of the impeller, 8 is a front shroud, and 9 is a rear shroud. When expressed as a distance from the motor shaft 6, the inlet shape of the blade 7 is approximately equal to the distance to the front shroud inlet, and is approximately parallel to the motor shaft.

In the conventional electric blower having the above configuration, the rotation of the impeller 1 generates dynamic pressure, which is kinetic energy, and static pressure, which is pressure energy. The air guide 2 attempts to guide the discharge flow having a dynamic pressure discharged from the impeller 1 to the atmosphere where the dynamic pressure is O while keeping the static pressure loss as small as possible.

One of the major problems with such conventional electric blowers is that they cause pulsation in the airflow in a low flow rate region, that is, a surging phenomenon occurs. One of the reasons for this is that in the low flow area, the airflow entering from the inlet 7 is immediately bent in the radial direction near the front shroud 8, as shown by the arrow.
In order not to reach the vicinity of rear shroud 9,
It was believed that the air inside the impeller became unnatural and caused pulsation.

Purpose of the Invention The present invention aims to eliminate these conventional drawbacks, and improves air blowing efficiency by modifying the impeller, and thereby reduces the surging phenomenon, which is the pulsation of airflow that occurs in low flow areas. The aim is to provide an electric blower that can be pushed to a lower flow rate range.

Structure of the Invention In order to achieve the above-mentioned object, the present invention makes the shape of the front edge of the blade on the inlet side so that the shape on the shroud side is the same as the inlet diameter and parallel to the motor shaft, and the shape on the rear shroud side is smaller than the inlet diameter. The front shroud is made to protrude toward the motor shaft side so as to have a small diameter, and the leading edge end is parallel to the motor shaft, and the connecting part of the leading end ends of the front shroud side and the rear shroud side is formed into a substantially dogleg shape. In addition, the connecting portion between the front shroud side having the same diameter as the inlet diameter at the front edge of the blade and the rear shroud side protruding toward the motor shaft is curved.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. In Figures 2 to 8, 10
is a motor, and the motor shaft 11 which is this rotation axis
The impeller 12 is connected to the spacer 13 and washer 14.
It is attached by tightening with a nut 15 via. An air guide 18 in which a diffuser part 16 and a return passage part 17 are integrated is located around the impeller, and a casing 20 is attached to the motor bracket upper part 19 by press fitting, covering the impeller 12 and the air guide 18. ing. The impeller 12 consists of a front shroud 21, a rear shroud 22, and blades 23, which are swaged together with a swage 24 provided on the blades 23. 25 is an inlet of the impeller 12. The inlet shape of the blade 23 is expressed by the distance from the center of the motor shaft 11 to the blade inlet end, and the distance near the front shroud 21 side is approximately the same as the distance to the inlet of the front shroud. They are substantially parallel, and the above-mentioned distance becomes smaller halfway toward the rear shroud 22.

In the above configuration, the operation is explained. The impeller 12 rotates as the motor shaft 11 rotates, and air is sucked into the impeller 12 through the inlet 25. At this time, as shown by the arrow in FIG. Since the impeller inlet 25 and the motor shaft 11 are approximately parallel to each other near the front shroud 21 at the inlet end of the blades 23, the air passes through the inlet 25 of the front shroud 21 even in a low flow range, and the air is immediately No centrifugal force is applied to the blade, and centrifugal force is applied when the blade inlet end comes closer to the motor shaft 11 than the inlet 25 of the front shroud 21. Therefore, a large amount of air flows to fill the rear shroud 22.

As shown in FIGS. 2 to 5, the impeller blade shape that achieves this effect includes a rear shroud 22 with a radius 27 from the vicinity of the end point 26 of a portion substantially parallel to the motor shaft 11 at the blade inlet end. An embodiment having a shape that leads to , and FIG. 6,
As shown in FIG. 7, an embodiment may be considered in which the inlet end of the blade 28 approaches the motor shaft 11 in a stepped manner from the inlet portion 30 of the front shroud 29 to a portion substantially parallel to the motor shaft 11.

FIG. 8 shows the relationship between the blade inlet shape, air blowing efficiency, and surging flow rate. Semi-conventional A
It can be seen that, compared to the samples B and C according to the present invention, the air blowing efficiency is higher and the flow rate at which surging occurs is lower.

Effects of the Invention As is clear from the above embodiments, in the electric blower of the present invention, the shape of the front edge of the blade on the inlet side is made so that the shape on the shroud side is the same as the inlet diameter and parallel to the motor shaft, and the shape on the rear shroud side is the same as the inlet diameter and parallel to the motor shaft. In this case, the diameter is smaller than the inlet diameter, and the leading edge is made to extend toward the motor shaft side so that it is parallel to the motor shaft. With this configuration, the airflow fills the impeller even in the low flow rate range, improving air blowing efficiency and reducing the flow rate that causes surging. be.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts of a conventional electric blower, FIG. 2 is a cross-sectional view of the main parts of an embodiment of the electric blower according to the present invention, and FIG. 3 is a front shroud of an embodiment of the impeller according to the present invention. 4 is a sectional view of one embodiment of the impeller according to the present invention, FIG. 5 is a developed view of the blades in one embodiment of the impeller according to the present invention, and FIG. 6 is a diagram of the impeller in another embodiment. 7 is a sectional view thereof, and FIG. 8 is a characteristic diagram showing the surging flow rate in the conventional example and each embodiment. 11... Motor shaft, 12... Impeller, 21...
...Front shroud, 22...Rear shroud, 2
3...Blade, 25...Entrance, 27...R.

Claims (1)

[Claims] 1. The impeller has a plurality of blades, a front shroud, and a rear shroud, and the shape of the blades at the front edge on the inlet side is such that the shape on the front shroud side is the same as the inlet diameter and the same as the motor shaft. The front shroud side and the rear shroud side are parallel to each other, and the rear shroud side is made to protrude toward the motor shaft side so that the diameter is smaller than the inlet diameter, and the front edge end is parallel to the motor shaft. An electric blower with a dogleg-shaped joint at the front edge. 2. The electric blower according to claim 1, wherein the connecting portion between the front shroud side having the same diameter as the inlet diameter at the front edge of the blade and the rear shroud side protruding toward the motor shaft is curved.