GB1589060A

GB1589060A - Impeller for cross-flow fans

Info

Publication number: GB1589060A
Application number: GB2043678A
Authority: GB
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1977-06-25
Filing date: 1978-05-18
Publication date: 1981-05-07
Also published as: AU524423B2; ATA429378A; FR2395415A1; AT362865B; DE2728727C2; AU3714678A; BE868435A; YU148778A; DE2728727A1; FR2395415B1

Description

(54) IMPELLER FOR CROSS-FLOW FANS (71) We, INTERNATIONAL STANDARD ELECTRIC CORPORATION, a Corporation organised and existing under the Laws of the State of Delaware, United States of America, of 320 Park Avenue, New York 22, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a cylindrical, bladed impeller for a blower, such as a transverse flow or tangential blower, comprising two circular end plates, and a number of curved fan blades extending therebetween.

Cross-flow fans are already known which have a particularly low running noise. Yet, as far as the low-noise level is concerned, increasing demands are placed on cross-flow fans because they are often used with apparatus, such as night current storage space heaters, heating ventilators, electric kitchen ranges, and the like, which are operated in low-noise environments, so that the inherent running noise of the cross-flow fan should be noticed as little as possible.

It is the object of the invention to further reduce the running noise of a fan embodying a cylindrical bladed rotor.

According to the invention, there is provided a cylindrical, bladed impeller for a fan comprising circular end plates and curved blades extending therebetween, wherein at least some of the blades are each provided with a longitudinal rib.

The invention will now be explained in greater detail with reference to Figures 1 to 4 of the accompanying drawings, in which: Figure 1 shows part of an impeller of a known cross-flow blower; Figure 2a shows the profile of a conventional blade of the impeller of Figure 1; Figure 2b shows the profile of a blade of an impeller according to an embodiment of the invention, and Figures 3 and 4 show graphs illustrating the noise behaviour of an impeller of the type shown in Figure 1, employing blades as shown in Figures 2a and 2b respectively.

As shown in Figure 1, the impeller of a cross-flow fan is a hollow cylindrical body provided at its ends with circular end plates 1, along the circumference of which blades 2 are arranged. In the case of conventional types of impellers, the blades 2 each consist of a narrow, smooth sheetmetal strip which, as is recognizable from Figure 2a, is curved by being bent. In contrast thereto, the blade according to the invention, in addition to being curved, as shown in Figure 2b, is provided with a longitudinal bead or rib 3 extending parallel to the longitudinal edges of the blade, and having a height a. The bead height a amounts to 0.03 times the blade width. The bead is preferentially located substantially along the centre of the blade.

The use of the blade of Figure 2b substantially reduces the noise of a cross-flow fan, as is illustrated in the graphs of Figures 3 and 4 based on comparative measurements. The measurements were carried out on a crossflow fan firstly with an impeller like that of Figure 1 with a diameter of 60 mm provided with blades according to Figure 2a, and then with a second impeller similar to the first but with blades according to Figure 2b. The results obtained with conventional blades are plotted by the solid lines, and the results obtained with the beaded blades are plotted by the dashlines.

In preparing the graphs shown in Figure 3, the evaluated sound pressure level for three operating points have been measured, and Figure 4 shows the maximum noise level at one third octave frequency bands across the noise spectrum relating to the same operating points.

As is evident from the ascertained measured values, the noise values produced by the impeller having the beaded blades, are considerably below those produced by impellers with blades without longitudinal beads.

WHAT WE CLAIM IS: 1. A cylindrical, bladed impeller for a fan comprising circular end plates and curved blades extending therebetween, wherein at least some of the blades are each provided with a longitudinal rib.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. (54) IMPELLER FOR CROSS-FLOW FANS (71) We, INTERNATIONAL STANDARD ELECTRIC CORPORATION, a Corporation organised and existing under the Laws of the State of Delaware, United States of America, of 320 Park Avenue, New York 22, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a cylindrical, bladed impeller for a blower, such as a transverse flow or tangential blower, comprising two circular end plates, and a number of curved fan blades extending therebetween. Cross-flow fans are already known which have a particularly low running noise. Yet, as far as the low-noise level is concerned, increasing demands are placed on cross-flow fans because they are often used with apparatus, such as night current storage space heaters, heating ventilators, electric kitchen ranges, and the like, which are operated in low-noise environments, so that the inherent running noise of the cross-flow fan should be noticed as little as possible. It is the object of the invention to further reduce the running noise of a fan embodying a cylindrical bladed rotor. According to the invention, there is provided a cylindrical, bladed impeller for a fan comprising circular end plates and curved blades extending therebetween, wherein at least some of the blades are each provided with a longitudinal rib. The invention will now be explained in greater detail with reference to Figures 1 to 4 of the accompanying drawings, in which: Figure 1 shows part of an impeller of a known cross-flow blower; Figure 2a shows the profile of a conventional blade of the impeller of Figure 1; Figure 2b shows the profile of a blade of an impeller according to an embodiment of the invention, and Figures 3 and 4 show graphs illustrating the noise behaviour of an impeller of the type shown in Figure 1, employing blades as shown in Figures 2a and 2b respectively. As shown in Figure 1, the impeller of a cross-flow fan is a hollow cylindrical body provided at its ends with circular end plates 1, along the circumference of which blades 2 are arranged. In the case of conventional types of impellers, the blades 2 each consist of a narrow, smooth sheetmetal strip which, as is recognizable from Figure 2a, is curved by being bent. In contrast thereto, the blade according to the invention, in addition to being curved, as shown in Figure 2b, is provided with a longitudinal bead or rib 3 extending parallel to the longitudinal edges of the blade, and having a height a. The bead height a amounts to 0.03 times the blade width. The bead is preferentially located substantially along the centre of the blade. The use of the blade of Figure 2b substantially reduces the noise of a cross-flow fan, as is illustrated in the graphs of Figures 3 and 4 based on comparative measurements. The measurements were carried out on a crossflow fan firstly with an impeller like that of Figure 1 with a diameter of 60 mm provided with blades according to Figure 2a, and then with a second impeller similar to the first but with blades according to Figure 2b. The results obtained with conventional blades are plotted by the solid lines, and the results obtained with the beaded blades are plotted by the dashlines. In preparing the graphs shown in Figure 3, the evaluated sound pressure level for three operating points have been measured, and Figure 4 shows the maximum noise level at one third octave frequency bands across the noise spectrum relating to the same operating points. As is evident from the ascertained measured values, the noise values produced by the impeller having the beaded blades, are considerably below those produced by impellers with blades without longitudinal beads. WHAT WE CLAIM IS:

1. A cylindrical, bladed impeller for a fan comprising circular end plates and curved blades extending therebetween, wherein at least some of the blades are each provided with a longitudinal rib.

2. An impeller as claimed in Claim 1, wherein each longitudinal rib is arranged along substantially the centre of the blade.

3. An impeller as claimed in Claim 1 or Claim 2, wherein each longitudinal rib extends parallel to the longitudinal edges of the blade.

4. An impeller as claimed in any of Claims 1 to 3, wherein the height of the longitudinal rib amounts to about 0.03 times the blade width.

5. An impeller substantially as hereinbefore described with reference to Figure 2b of the accompanying drawings.

6. A fan having an impeller as claimed in any preceding Claim.