US3561906A

US3561906A - Centrifugal fan

Info

Publication number: US3561906A
Application number: US795585*A
Authority: US
Inventors: Karl-Erik Fermer
Original assignee: Svenska Flaktfabriken AB
Current assignee: Svenska Flaktfabriken AB
Priority date: 1968-01-31
Filing date: 1969-01-31
Publication date: 1971-02-09
Anticipated expiration: 1988-02-09
Also published as: NL6901501A; FR2001058A1; DE1904311A1; GB1234733A; BE727784A

Abstract

A CASING FOR A CENTRIFUGAL FAN COMPRISING A HOLLOW BOX STRUCTURE HAVING SQUARE CORNERS, ONE END WALL HAVING AN EXHAUST OPENING AT ONE CORNER AND AN ANGULARLY DISPOSED SHIELDING PLATE AT THE OTHER CORNER. THE FAN WHEEL AXIS IS OFFSET FROM THE CENTER OF THE BOX TOWARD SAID SHIELDING PLATE. THE CASING IS PREFERABLY FORMED BY FOUR UNIFORMSIZED BOX-SHAPED ELEMENTS WHICH ARE ABUTTED AND JOINED AS SHOWN IN FIG. 1.

Description

Feb. 9, 1971 KARL-ERIK FERMER 3,561,996

- CENTRIFUGAL FAN Filed Jan. 31, 1969 2 Sheets-Sheet 1 FIGI.

INVENTORZ KAR L ERI K FERME'R ATTYS.

1971 KARL-ERIK FERMER 3,561,906

CENTRIFUGAL FAN Filed Jan. 31, 1969 I 2 Sheets-Sheet 2 FIG. 2.

. INVENTOR'. B KARL-ERIK FERMER ATTYS,

United States Patent 3,561,906 CENTRIFUGAL FAN Karl-Erik Fermr, Jonkoping, Sweden, assignor to Aktiebolaget Svenska Flaktfabriken, Stockholm, Sweden Filed Jan. 31, 1969, Ser. No. 795,585 Claims priority, application Sweden, Jan. 31, 1968, 1 323/68 Int. Cl. F0 4d 29/40, 17/08 US. Cl. 415-206 2 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a new and simple design of a centrifugal fan consisting of a casing provided with inand outlets and a centrifugal fan wheel rotatably journalled in same.

The manufacture of centrifugal fans of conventional design, i.e. with a spiral-shaped casing, includes the following working moments:

(1) Contour cutting of the casing sides by means of a template.

(2) Forming the casing backplate to a curving radius varying in a certain manner.

(3) Joining the casing sides and backplate along a curved line.

These working moments depend on templates and special tools, and they have proved to be very time-consuming and represent a great lot of the total manufacturing cost. The invention is based on the discovery that the spiral-shaped fan casing without any worth mentioning deterioration of the efficiency of the fan can be substituted by' a casing of a more simple geometrical form, which has the result that the manufacturing cost can be considerably reduced. The new and characterizing feature for the invention is that the casing is provided with two end walls, of which one or both is equipped with said inlet and four intermediate plane walls, which walls are located mainly at such a distance from the centre of the wheel that the walls form tangents to an imaginary back plate of conventional spiral shape, and that the wall being located at the smallest distance from the centre of the wheel is provided with the above-mentioned outlet located close to the corner line at the one of the plane walls touching each other, which is located at the greatest distance from the centre of the wheel.

A suitable embodiment of the invention is characterized in that between the plane wall located next to the centre of the wheel and the subsequent plane wall is arranged a plate shielding the corner.

In order to further reduce the manufacturing cost and to simplify the mounting especially of bigger fans the casing can be provided with two squared or rectangular wall elements and four, preferably between themselves uniform and box-shaped elements of same size each consisting of a bottom, two opposite rectangular side walls and an intermediate end wall, which box-shaped elements are arranged in a closed circuit in order to enclose together a space with a squared or rectangular cross-section and with the end wall of each box-shaped element located in the same plane as the bottom in the abutting box-shaped 3,561,906 Patented Feb. 9, 1971 "ice element and with the side walls of the box-shaped elements connected to the above-mentioned squared or rectangular wall elements, of which at least one is provided with an inlet opening.

The invention will now be closer described with reference to the enclosed drawing showing an exemplifying embodiment of the invention.

FIG. 1 is a perspective view of a centrifugal fan embodying the present invention; and

FIG. 2 is a sectional view through the fan shown in FIG. 1.

In the drawing 1 designates a fan casing provided with an inlet 2 and an outlet 3. 4 designates a fan wheel of centrifugal type, the shaft of which 5 is rotatably journalled in two bearing houses 6 supported by stiffening means 7 fastened to the casing. The casing :1 is according to the invention provided with two

end walls

8 and 8 and four

intermediate plane walls

10, 11, 12 and 13. The last-mentioned plane walls are located at such a distance from the centre of the wheel that they form tangents to an imaginary back plate 14 of conventional spiral shape. Between the walls 10 and 11 is in the case shown arranged a plate 15 shielding the intermediate corner.

As shown in FIG. 1, the casing 1 is formed by four box-shaped peripheral elements designated 21, 22, 23, and 24, each element comprising a bottom wall a, and end wall b and side walls 0. The

peripheral elements

21, 22, 23 and 24 are arranged in closed circuit order so that the bottom 21-a and the end 22-h form the wall 11, the bottom 22-a. and the end 23-b form the wall 12, the bottom 23a and the end 24-b form the wall 13, and the bottom 24-a and the end 21-b form the wall 10. The sides 0 form the marginal portions of the walls 8 and a filler element 25 having the inlet 2 is mounted to form the central part of the front wall 8, and a similar filler element is provided to form the central part of the rear wall 8.

What I claim is:

1. In a centrifugal fan consisting of a casing and a centrifugal fan wheel rotatably journaled in said casing, said casing comprising two sides having square corners, at least one of said sides having an inlet opening to the center of said fan wheel, four plane walls intermediate said sides around the boundary thereof to form a hollow box with square corners, said fan being journaled on an axis offset frorn'fthe center of said sides towards a corner of said hollow box formed between a first and a second of said plane walls so that all four of said Walls form tangents to an imaginary back plate of conventional spiral shape, said first wall having an outlet opening therein adjacent to the corner formed between said first wall and a fourth of said walls, and an oblique guiding surface in said first corner extending from said first plane wall to said second plane wall, tangential to said imaginary spiralshaped back plate, said four plane walls and said guide plate providing an open casing directly confronting the fan wheel without interposition of a back plate therebetween, the improvement wherein said casing comprises four boxlike peripheral elements interconnected in a closed circuit, each element having a bottom, two opposite side portions and an end, the bottom of each element being coplanar with the end of an adjacent element to provide said four plane walls, the respective side portions of all elements being coplanar to form the outer marginal area of said casing sides, and including filler elements positioned within the marginal area formed by said boxshaped elements to form the central parts of said casing sides, at least one of said filler elements having said inlet opening therein.

2. A centrifugal fan according to claim 1 wherein said 3,174,682 3/ 1965 Wilfert et a1. 230133 box-like peripheral elements are of the same size and 3,312,389 4/1967 Matsui "230-127 said filler elements are square. 3,286,914 11/1966 Bauerstock 230-133 References Cited 5 FOREIGN UNITED STATES PATENTS 741,975 12/1955 Great Britain 230128 2,482,519 9/1949 SchWarz 230128 HENRY F. RADUAZO, Primary Examiner 2,557,201 6/1951 Punt 230-433 2,659,294 11/1953 Hersperger 415-204 US. Cl. X.R.

2,854,188 9/1958 Shornphe 230-133 10 415204