JPH01249982A - Centripetal type blower - Google Patents

Abstract

PURPOSE:To improve the performance of a blower in the low flow region by disposing a plurality of guide blades having each a plane including a segment orthogonal to a rotary shaft of an impeller in the suction region of the impeller. CONSTITUTION:When a motor 26 is driven under the opened condition to rotate an impeller 21, air flow W sucked radially from an inflow guide plate 25 through a guide blade 27 is accelerated by each blade 23 while being discharged axially or obliquely outward. On the other hand, when the flow is throttled from the opened condition, the effect of a centrifugal force is successively increased, so that a contraflow is generated in the suction region. However, since a mounting angle alpha=0 deg., i.e. the guide blade 27 radially mounted exists in the suction region, the contraflow is prevented by blocking air flow flowing out the outer peripheral direction of the impeller.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a blower that sucks in fluid centripetally from the outer circumference and discharges it from the center.

BACKGROUND OF THE INVENTION A conventional blower of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-593.
There is something like the one shown in the publication, and specifically it had a structure as shown in Figure 4.

That is, an impeller 1 having a hub 2 and a plurality of blades 3 implanted on the outer peripheral surface thereof, a bell mouth 4 surrounding the outer periphery of the impeller 1, and 2 constituting a passage in the suction area.
It is composed of two inflow guide plates 5. When the impeller 1 is rotationally driven by the motor 6, the air flow W sucked in from the radial direction through the passage between the inflow guide plates 5 is accelerated by each blade 3 and discharged in the axial direction or diagonally outward. .

Problems to be Solved by the Invention However, with the above configuration, work is done against the centrifugal force acting on the fluid flow, so when the flow rate is throttled down, backflow occurs in the suction region, causing a stall phenomenon. In other words, in the individual performance of the blower shown in the dimensionless characteristics in Figure 3,
As shown by the dotted line P', the pressure coefficient ψ3 obtained in the low flow rate region
The problem is that the stable operating region, the so-called right-sloping curve range, in the flow coefficient-pressure coefficient characteristic, which is a dimensionless characteristic, is low, and the centripetal flow becomes unstable.

The present invention solves these conventional problems, and aims to improve the performance of the blower of the prior application as described above in a low flow rate region.

Means for Solving the Problems In order to solve the above problems, the present invention provides an impeller configured by providing a plurality of blades on the outer peripheral surface of a hub, a bell mouth that covers the outer periphery of the impeller, an inflow guide plate constituting a passage in a suction region, and a plurality of guide vanes each having a plane including a line segment orthogonal to the rotation axis of the impeller are disposed in the suction region of the impeller. be.

Effect The present invention has the above-described configuration, so that even when the flow rate is reduced, the guide vanes block the airflow flowing toward the outer circumferential direction of the impeller due to centrifugal force, thereby suppressing backflow in the suction region and reducing the tendency to stall. This results in a stable operating area of the blower and a stable centripetal flow.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

As shown in Fig. 1 and Fig. 2, this blower has no.
an impeller 21 having a plurality of blades 23 planted on its outer circumferential surface; a bell mouth 24 surrounding the outer circumference of the impeller 21; and two inflow guide plates constituting a passage in the suction area. It consists of 25. Furthermore, a plurality of guide vanes 27 are provided on the suction side of the impeller 21 to prevent airflow from flowing out toward the outer circumferential direction of the impeller due to centrifugal force. Also, the installation angle α of these guide vanes 27 with respect to the center line is α=
o', that is, in the radial direction, and at the same time, the guide blade 27 is thickened and has a substantially triangular prism shape with an apex angle θ of 30°. In addition, 26 is a motor, and 28 is an impeller 2.
1 rotation axis is shown. Solid arrows indicate air flow W.

Next, the operation of the illustrated blower will be explained.

When the impeller 21 is rotated by driving the motor 26 in the open state, the air flow W sucked in from the inflow guide plate 25 in the radial direction through the guide vanes 27 is accelerated by each vane 23 and axially Alternatively, it is discharged diagonally outward. On the other hand, when the flow rate is reduced from the open state, the influence of centrifugal force gradually increases, causing backflow in the suction region, which tends to cause a stall phenomenon.

However, since there is a guide vane 27 installed in this suction region with the installation angle α set to α=0°, that is, in the radial direction, backflow is prevented by blocking the airflow flowing toward the outer circumferential direction of the impeller. be done. As a result, a stable operating range of the blower and a stable centripetal flow can be ensured even in a low flow rate range, and high static pressure can be obtained.

In addition, in this embodiment, the apex angle θ of the guide vane 27 attached to the suction region is set to θ=30°, and by making the guide vane 27 into a thick substantially triangular prism shape, It is possible to suppress the swirling flow along the line and obtain higher static pressure.

FIG. 3 shows the performance improvement effect of the embodiment of the present invention in terms of dimensionless characteristics of a single blower in comparison with the conventional one. In the figure, the curve P (shown by a solid line) is for the embodiment of the present invention, and the curve P' (shown by a broken line) is for the conventional example, showing the flow coefficient-pressure coefficient characteristics made dimensionless by the impeller outer diameter. It will be understood that the curve P gives better results than the curve P'.

Effects of the Invention As described above, the blower of the present invention provides the following effects.

Backflow in the medium suction region is suppressed, preventing the tendency to stall, and stable operation is possible even in low flow regions.

(II) It has the excellent effect of being able to obtain a higher static pressure in a low flow rate range and being applicable to applications with higher internal resistance.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a blower according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. FIG. 4 is a sectional view of a conventional blower. 21... Impeller, 22... Hub, 23
...feather, 24 ...bellmouth, 25
...Inflow guide plate, 27...Guide vane, 2
8...Rotation axis. Name of agent: Patent attorney Toshio Nakao and 1 other person 2I
・°゛impeller 22-hub Fig. 1 23 ・・
・Feather 24-・Bellmouth F! Figure 2, Figure 3, Flow Rate, Diagram 4, Figure 4

Claims (1)

[Claims] (1) an impeller configured with a plurality of blades provided on the outer circumferential surface of a hub; and a bell mouth that covers the outer circumference of the impeller;
an inflow guide plate that constitutes a passage in a suction region, and a centripetal type in which a plurality of guide vanes having a plane including a line segment orthogonal to the rotation axis of the impeller are disposed in the suction region of the impeller. Blower.