JPH04164196A - Impeller for multiblade blower - Google Patents

Abstract

PURPOSE:To suppress the reduction of the blowing performance by specifying the quantity of the blades of an impeller which is constituted into a cylindrical form by arranging a plurality of blades, keeping intervals. CONSTITUTION:An impeller 1 is constituted into a cylindrical form by arranging a number of blades 4 having an arcuate section in parallel to a rotary shaft between a disc-shaped main plate 2 and a subplate 3 having an air inflow inlet at the center, and the quantity Z of the blades 4 is set by using the expression I. When the impeller 1 having such constitution is revolved, the air drawn into the impeller 1 flows out into a casing 5 by the centrifugal force of the impeller 1, and further flows in the direction of arrow shown by the full line along the inner surface of the wall of the casing 5, and is discharged from a discharge port 6, and the impeller 1 acts as a blower. Accordingly, the lowering of the blowing performance is suppressed and the high performance can be maintained while suppressing the noise low.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an impeller for a multi-blade blower used in an air conditioner or the like.

2. Description of the Related Art Conventionally, as shown in FIG. 9, an impeller 11 of this type of multi-blade blower has a blade 1 having an arc-shaped cross section between a main plate 12 and a sub-plate 13.
A cylindrical structure is adopted in which a large number of 4 are arranged parallel to the rotation axis and spaced apart from each other. When designing the impeller 11, a design method has been adopted based on the law of proportionality, in which the impeller 11 is designed proportionally based on an impeller having a known blowing performance.

Problems to be Solved by the Invention However, when such an impeller 11 is injection molded using resin molding, etc., the thickness of the blades 14 must be within a certain range due to constraints such as processing strength of the blades 14. That is, specifically, it was impossible to set it to about 1 mm or less. Therefore, especially when reducing the outer diameter of the impeller 11, if a proportional design is performed based on the conventional proportionality law, in which the number of blades 14 is kept constant and the blades 14 have geometrically similar shapes, the inter-blade passage 15 There was a problem in that the performance of the blower was lower than the designed performance due to an increase in fluid resistance due to the spacing becoming too narrow.

That is, the standard impeller 1 with an outer diameter of D20 shown in FIG.
1' is designed to be reduced to a geometrically similar shape using the law of proportion as the impeller 11 with an outer diameter of D shown in FIG. 7, the following relationship exists.

1+o=p+ tlo -δpo -δto... (1) On the other hand, the 8th
As shown in the figure, the thickness t of the blade 14. 111-21-t when designed with constant.

- δI) o -to ... (2) (1) and (
In formula 2), δ: Proportional design ratio (-D2/D2o) D2°: Outer diameter p0 of standard impeller 11'': Pitch to of blades 14 of standard impeller 11°:
Thickness D2 of blades 14 of standard impeller 11'': Inner diameter p of proportionally designed impeller 11: Pitch 1 of blades 14 of proportionally designed impeller 11.: Inter-blade road 15 of proportionally designed impeller 11 Spacing j+o: Thickness 11□ of blades 14 of proportionally designed impeller 11
: Thickness of wing 14. Impeller 1 designed proportionally with constant
In other words, in equations (1) and (2), in the case of a reduced design, Dz<D2°. Therefore, 11°〉111, and the thickness t of the blade 14. When designed proportionally with constant
When the thickness of the blade 14 is also made proportionally thinner, the road 15 between the blades is
The distance between them becomes narrower. In FIGS. 6 to 8, D is the inner diameter of each impeller 11, and io is the interval between the inter-blade roads 15 of the reference impeller 11''.

The present invention solves the above problem, and suppresses the increase in fluid resistance on the inter-blade road by reducing the number of blades in order to suppress the decrease in the distance between the inter-blade roads due to the thickness of the blades. It is something.

Means for Solving the Problems In order to solve the above problems, the present invention provides an impeller having a cylindrical configuration in which a plurality of blades are spaced from each other, and the number Z of the blades is πD+45t(+-δ) (D = outer diameter of impeller, t: blade thickness, Z: number of blades, δ
: proportional design ratio -D/65).

Effect: With the above configuration, it is possible to suppress an increase in fluid resistance within the inter-blade passage due to a decrease in the interval between the inter-blade roads, and to suppress a decrease in air blowing performance.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 and 2 show cross sections of a multi-blade blower according to an embodiment of the present invention. As shown in FIGS. 1 and 2, the impeller 1 has blades 4 having an arc-shaped cross section between a disk-shaped main plate 2 and a sub-plate 3 having an air inlet in the center. A large number of blades are arranged in parallel to form a cylindrical shape, and the number Z of the blades 4 is set using the formula ( ]). That is, the outer diameter of the impeller 1 is D2, and the thickness of the blade 4 is Lo, where δ=D2/65. Note that 5 is the spiral casing, 6 is the discharge port of the casing 5, 7 is the air supply port, and 8 is the blade. solid arrows indicate air flow.

In the above configuration, when the impeller 1 rotates, the air sucked into the impeller 1 flows out into the casing 5 due to the centrifugal force of the impeller 1, flows along the inner wall of the casing 5, and flows through the discharge port. It is discharged from 6 and operates as a blower.

Next, equation (3) will be explained in detail. The impeller 11' shown in FIG. 6 has a blade 4 having a thickness t as shown in FIG.

When designing with constant
2) For the equation, the interval 1 of the interwing road 8 is 1-■. The number of blades 14 of the impeller 11', which is the design standard of 72 degrees, is changed to Z in the reduced design of the impeller 1. That is, the following relationship exists between the embodiment shown in FIG. 3 and FIGS. 6 and 8.

πD20 1-δpo-to-δ□ -to...(5) where l
=I+o, δ-D 2 / D 2゜ Therefore πD2
+ Z20 t o (1-σ) Here, for the impeller that is the standard for proportional design, its outer diameter D2° is D2
When o=65mm, the inner and outer diameter ratio ν is sea D1o/D
zo=0.88, the number of blades 3 is 220, Z2o-45,
Furthermore, it has been experimentally confirmed that an impeller in which the total area of the outer surface of the arcuate blades is larger than the surface area of the outer peripheral side surface of the impeller has higher performance than a conventional impeller. Figure 4 shows the blowing performance of this blower in comparison with a conventional blower. FIG. 4 is shown using dimensionless characteristics in which the horizontal axis is the flow coefficient φ and the vertical axis is the pressure coefficient φ. Further, FIG. 5 shows the experimental results of the relationship between the number of blades Z and aerodynamic performance in relation to the pressure coefficient φ, which is a dimensionless number. Figure 5 shows the pressure coefficient ratio φ/φ on the vertical axis.
. φ is the pressure coefficient near the normally used operating point in terms of the number of blades in the capacity for an impeller with an inner/outer diameter ratio of 0.88, and φ.

is the maximum value of the pressure coefficient near the operating point obtained when changing the number of blades. As shown in Figure 5, there is an optimal value for the number of blades Z for aerodynamic performance, but the
The results shown in the figure show that even if the number of impellers is increased or decreased to about 75% of the maximum performance, performance superior to that of conventional impellers can be obtained. That is, the lower limit of the number of blades Z is about 45. Therefore, the lower limit of the number Z of blades of the standard impeller is about 45, and by substituting other values into equation (6), we get δ=D/65. Although the number of blades determined by equation (3) is the lower limit, it goes without saying that the upper limit is less than 45, which is the number of blades of the impeller used as a reference.

Effects of the Invention As described above, the impeller of a multi-blade blower based on the design of the present invention provides the following effects.

In other words, when downsizing the impeller by injection molding or other methods that do not allow the thickness of the blades to be made thinner, it is possible to suppress the increase in fluid resistance within the inter-blade passages due to the reduction in the interval between the inter-blade passages, thereby suppressing the deterioration of air blowing performance. This makes it possible to downsize the blower while maintaining low noise and high performance.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an impeller of a multi-blade blower according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the E-I line in Fig. 1, Fig. 3 is an enlarged view of the main parts of the impeller, and Fig. 4. is a characteristic diagram comparing the performance of the same impeller with a conventional one, Figure 5 is a characteristic diagram showing the number of blades and aerodynamic performance of the same impeller, and Figures 6 to 8 are explanations of the design method of the same impeller. FIG. 9 is an enlarged sectional view of a main part of an impeller for a conventional multi-blade blower. ■...Blower, 2...Main plate, 3...
...Subplate, 4...Wing, butt...Road between the wings, Dl...Inner diameter, D2...Outer diameter, 1.
...The spacing between the wing passages. Name of agent: Patent attorney Akira Okaji and two others 1---
*Wind clothes 4- Tsubasa Figure 1 A Figure 6 Figure 7'll ``Kan' 41z 11 and tlo 勺謬 Figure 8 Figure 15 //

Claims (1)

[Scope of Claims] The number Z of the blades of an impeller configured in a cylindrical shape with a plurality of blades spaced apart from each other is Z≧45πD/{πD+45t(1−δ)} (D: outside of the impeller diameter, t: blade thickness, Z: number of blades, δ: proportional design ratio = D/65).