EP1649170A1

EP1649170A1 - A tangential fan

Info

Publication number: EP1649170A1
Application number: EP04740424A
Authority: EP
Inventors: Nathaniel Mulcahy
Original assignee: Emerson Appliance Motors Europe SRL
Current assignee: Askoll P&C SRL
Priority date: 2003-06-30
Filing date: 2004-06-29
Publication date: 2006-04-26
Also published as: ITTO20030495A1; WO2005003568A1

Abstract

A tangential fan (1) includes an air guide structure (2) with a bladed impeller (3) mounted therein for rotation about an axis (A). This structure (2) includes two facing end walls (5, 6), and at least one side wall (13, 14) extending about the said axis (A), between the end walls (5, 6) and in which are defined an intake or suction aperture (15) and an output or delivery aperture (16), angularly spaced from one another about the said axis (A); an intermediate wall (14) extending between the said apertures (15, 16), including contiguous first and second wall portions (14a, 14b) adjacent the intake aperture (15) and the output aperture (16) respectively. At least part of the first portion (14a) of the said intermediate wall (14) has a plurality of closely arranged through holes (17), arranged in a substantially random configuration.

Description

A tangential fan

The present invention relates to a tangential fan.

More specifically, the subject of the invention is a _^tangential fan having an air guide structure with a bladed impeller mounted therein for rotation about an axis; the said structure including: two facing end walls, and at least one side wall extending around the said axis, between the end walls, with an intake or suction aperture and an outlet or delivery aperture, angularly spaced with respect to the said axis; extending between the said two apertures, there being, an intermediate wall including first and second contiguous wall portions, adjacent the intake aperture and the outlet aperture respectively.

One object of the present invention is to provide a tangential fan of the type described above, having improved characteristics and performance, with regard in particular to operating noise, air delivery and the effectiveness of the cooling action.

This and other objects are achieved according to the invention by a tangential fan of the type specified above, characterised in that at least part of the said first portion of the intermediate wall has a plurality of closely spaced through holes, arranged in a substantially random pattern.

Other characteristics and advantages of the invention will become apparent from the detailed description which follows, provided purely by way of non-limitative example, with reference to the appended drawings, in which: figure 1 is a perspective view of a tangential fan according to the present invention; and figure 2 is a partially sectioned view, taken substantially on the line II-II of figure 1.

A tangential electric fan according to the invention is indicated 1 in figure 1.

This electric fan includes a support and air guide structure, generally indicated 2.

An impeller or fan, generally indicated 3 in figure 1, is mounted for rotation in the structure 2 in a manner known per se. The fan 3 is rotatable by means of an electric motor 4, an a.c. motor for example, such as a shielded-pole asynchronous motor.

In the embodiment illustrated by way of example, the support and air guide structure 2 includes, for example, two facing end walls 5 and 6, made of cut, pressed and folded sheet metal. Respective supports 7 (in figure 1) and 8 (in figure 2) are mounted on these walls 5 and 6 for the impeller or fan 3, which in operation is rotatable about an axis indicated A in figure 2.

The fan 3 could be made of metal or a plastics material and in the embodiment illustrated is configured as a .generally cylindrical cage-like structure, with two end rings 9 and 10 and a pair of intermediate rings 11 with a circular array of preferably arcuate blades 12 connected thereto. The support and air guide structure 2 also includes at least one side wall, and preferably a pair of side walls, extending around the axis of rotation A of the fan, between the end walls 5 and 6.

In the embodiment illustrated by way of example, the structure 2 essentially includes two side walls, indicated 13 and 14. The wall 13 includes a first arcuate wall portion 13a, the concave face of which faces the axis A. Preferably, though not necessarily, the distance from the arcuate wall portion 13a to the axis A increases gradually in the sense of rotation of the fan 3 , shown by the arrow F in the drawings .

The wall 13 includes a second wall portion 13b (figure 2) , which, in the example illustrated, is essentially planar and joins the arcuate portion 13a described above.

The side wall 14 of the embodiment shown by way of example is C-shaped in cross section, with the convex face thereof facing the axis A.

In particular, this wall 14 has a main intermediate portion 14a, between two end portions 14b and 14c.

Between the wall 13 and the wall 14 in the support and air guide structure 2 is defined an air intake or suction aperture 15 and an air output or delivery aperture 16, the two apertures being angularly spaced.

In particular, the intake or suction aperture 15 is defined between the portion 14c of the wall 14 and the portion 13a of the wall 13 (see figure 2) . The outlet or delivery aperture 16 is in particular formed between the portion 13b of the wall 13 and the portion 14b of the wall 14.

Considering once again the intermediate wall 14, the contiguous portions 14a and 14b thereof preferably form a sort of. dihedral, the convex face of which faces into the support and air guide structure 2.

According to the present invention, at least part of the portion 14a of the wall 14 has a plurality of closely spaced through holes 17, arranged in a substantially random pattern, that is not in an organized configuration.

In the illustrated embodiment, the portion 14a of the intermediate wall 14 has through holes 17 over substantially its entirety. These apertures could all be of the same diameter or the diameters thereof could vary at random within a predetermined range.

Overall, the dimensions and the density of the holes 17 can conveniently be such that they occupy more than 50% of the surface of the portion 14a of the intermediate wall.

As illustrated indicatively, that is qualitatively, by the flow lines shown as broken lines in figure 2, a flow of air passes in operation through the holes 17 into the structure 2 as a result of the rotation of the impeller 3. The substantially random distribution of these apertures 17 means that any turbulence created is largely cancelled out. Consequently a considerable increase in air delivery can be achieved, without leading to an increase in noise during operation. Comparative tests run by the applicant have shown that, by comparison with a fan in which the wall 14 is entirely imperforate, it is possible to achieve an increase in air delivery by around 16%, accompanied by an absolute reduction in operating noise by around 2-3dB.

Although in the embodiment shown by way of example in the drawings the portion 14a of the intermediate wall 14 has holes all over it, the scope of the present invention extends to embodiments where this portion of the wall 14 has perforated areas and areas which are either not perforated and/or consist entirely of window. It is also possible to form areas with holes arranged in an organized configuration, at the ends of the wall 14a, for example, in order to create turbulent airflows which can be used to "contain" the rest of the exiting air flow. By a suitable distribution perforated areas and imperforate areas or areas formed entirely as windows it is possible to control the direction of the partial flows that make up the air flow delivered by the fan in order, for example, to satisfy particular requirements as to how the cooling action should be distributed in the environment where the fan is in use.

The provision of closely spaced holes, in a substantially random configuration in at least part of portion 14a of the intermediate wall 14 is both simple and inexpensive and offers the benefits described above.

In an embodiment not shown in the drawings, additional benefits can be obtained by associating a wall with closely spaced through holes, in a substantially random configuration, with at least part of the air intake or suction aperture 15. This arrangement is more complicated to construct and more expensive, however.

In a further embodiment which is not illustrated, a perforated diaphragm or wall, with closely arranged holes in a random configuration, can also be associated with the outlet aperture 16 of the air guide structure 2 of the fan. This arrangement makes it possible to homogenize the direction and speed characteristics of the outflow of air.

Naturally, the principle of 'the invention remaining unchanged, embodiments and manufacturing details may vary widely from those described and illustrated purely by way of non-limitative example, without departing thereby from the scope of the invention, as claimed in the appended claims.

Claims

A tangential fan (1) including an air guide structure (2) with a bladed impeller (3) mounted for rotation therein about an axis (A) ; the said structure (2) including two facing end walls (5, 6) ; and at least one side wall (13, 14) extending about the said axis (A) between the end walls (5, 6) , and in which are defined an intake or suction aperture (15) and an output or delivery aperture (16) angularly spaced from one another about the said axis (A) ; an intermediate wall (14) extending between the said apertures (15, 16) and including first and second contiguous wall portions (14a, 14b) , adjacent the intake aperture (15) and the output aperture (16) respectively; the fan being characterised in that at least part of the first portion (14a) of the said intermediate wall (14) has a plurality of closely spaced through holes (17) in a substantially random configuration.

2. A tangential fan according to claim 1, in which the said holes (17) through the intermediate wall (14) have substantially random dimensions within a predetermined range.

3. A tangential fan according to claims 1 or 2, in which the said holes (17) through the intermediate wall (14) are essentially circular.

4. A tangential f n according to any preceding claim, in which the aforesaid first portion (14a) of the intermediate wall (14) has one or more areas which are imperforate and/or one or more fenestrated areas .

5. A tangential fan according to any preceding claim, in which a perforated lateral wall with a plurality of closely spaced through holes in a substantially random configuration is associated with the intake or suction aperture (15) .

6. A tangential fan according to any preceding claim, in which a perforated wall, with a plurality of closely spaced through holes in a substantially random configuration is associated with the output or delivery aperture (16) .