GB2344619A

GB2344619A - Air duct for an electric fan

Info

Publication number: GB2344619A
Application number: GB9923754A
Authority: GB
Inventors: Andrea Giribaldi; Riccardo Ghio
Original assignee: Gate SRL
Current assignee: Gate SRL
Priority date: 1998-10-08
Filing date: 1999-10-07
Publication date: 2000-06-14
Anticipated expiration: 2019-10-07
Also published as: DE19948074A1; FR2784423A1; FR2784423B1; IT1304683B1; ITTO980849A1; GB9923754D0; GB2344619B

Abstract

The duct 3, comprises an outer annular element 10 which extends in the vicinity of the periphery of the blades 5 of the impeller, at least one inner annular element 11 coaxial with the outer annular element 10 and with the impeller, and a plurality of interconnection elements 13 which extend, spaced apart angularly, between the inner and outer annular elements 11, 10; the interconnection elements 13 are shaped in a manner such that they can deflect the flow towards the axial direction, reducing the tangential component of the velocity of the air-flow between the annular elements 10, 11 when the impeller is in operation. The impeller blades may be curved forwardly and the interconnection elements may be curved rearwardly relative to the direction of rotation of the impeller. The interconnection elements may have a constant set angle or a radially outwardly decreasing angle of inclination (fig. 4).

Description

1 2344619 AIR DUCT FOR AN ELECTRIC FAN The present invention relates to an

air duct for an electric fan comprising an impeller with a plurality of blades and w_'th L a hub to which an electric drive motor is connected, particularly for cooling the radiator of a motor vehicle.

More specifically, the subject of the invention is a duct comprising:

an outer annular element which extends. in the vicinity of the periphery of the blades of the impeller, at least one inner annular element coaxial with the outer annular element and with the hub of the impeller, and a plurality of fixed interconnection elements which extend, spaced apart angularly, between the inner and outer annular elements.

In known ducts, the fixed interconnection elements are in the form of substantially radial strips and have a predominantly structural function.

The object of the present invention is to provide a duct of the type specified above which can reduce the noise generated by the electric fan in operation and which achieves an advantageous recovery of the kinetic energy of the air-flow induced by the impeller through the duct.

Claims

This and other objects are achieved, according to the invention, by an air

duct, the main characteristics of which are defined in appended Claim 1.

f a (Uct according to the inven-ion, the xe a elements perform an advantageous flow- ccrrec-:ing func-ion in addi-:_'on r-o a structural function.

Further characteristics and advantages of the invention will become clear from the following detailed description, given wizh reference to the appended drawings, provided purely by way of non-limiting example, in which:

Figure 1 shows an electric fan with an air duct according to the prior art, partial ly-sectioned in an axial plane, Figure
2 is a projection of the electric fan of Figure 1 and of the associated duct i n a frontal plane, taken in accordance with the arrow II in Figure 1, Figure
3 is a projection, in a frontal plane, of an electric fan with a duct according to the invention, Figure 4 is a view similar to that of Figure 3 and shows a variant, and Figures 5 and 6 are 'linearized views, in section and on an enlarged scale, taken on the lines V-V and VI-VI of Figures 3 and 4.

In Fiqure 1, a cooling unit to be associated with a radiator (not shown) of a motor vell-ic-le, is generally indicated 1.

The uni-I comprises an electric fan 2 mounted in an air-duct, generally indicated 3.

The electric fan 2 comprises an impeller 4 with a plurality cff blades 5 which extend between a cen-,--al hub 6 and a per 4 -phera-- ring coaxial with tre hub.

The electric fan 2 also comprises an electric motor 8 for rotating the impeller 4, for example, in the direct-ion of the arrow F of Figure 2.

In the embodiment illustrated, the blades 5 of the impeller 4 are arcuate and have respective leading edges 5a which, in the projection in a frontal plane (Figure 2), are curved (at least predominantly) forwardly, in the direction of rotation F of the impeller.

The air duct 3 comprises an annular band 9 coaxial with the axis of the electric fan 2 and surrounding the impeller 4.

Downstream of the impeller 4 in the direction K (Figure 1) of the airflow brought about by the impeller, the duct 3 has an outer annular element 10 connected to the band 9 and an inner annular element 11 coaxial with the annular element 10 and with the electric fan 2.

In the embodiment shown in Figures 1 and 2, appendages 12, to which the motor 8 of the electric fan is fixed firmly, in known manner, for example, by screws or bolts, extend from the inner edge of the ring 11.

An array of fixed, angularly spaced-apart interconnection elements 13 extends between the outer and inner annular elements 10 and 11.

As can be seen in Figures 1 and 2 and as stated above, according to the prior art, the interconnection elements 13 are substantially in the form of strips arranged predominantly radially and have a purely structural function.
4 Fiqure 3, which is similar -t:c F--:g,-,--e 2, shows a cooling unit I invention. I comprising an air duct according to the in Figure 3, parts and elements already described have again been attributed the same reference numerals.

in the cooling unit I of Figure 3 (and of Figures
5 and 6) the interconnection elements 13 are shaped in a manner such that they can deflect the flow towards the axial direction K (in Figure 1), reducing and potentially eliminating the tangential component of the velocity of the a 4 r-f low urged through the region between the annular elements 10 and 11 by the impeller 4 in operation. These interconnection elements thus perform a flow-dynamics function in addition to a structural function. In particular, they act as flow correctors.

T a _L_1 - as in the embodiment illustrated - the radially outer portions of blades 5 of the impeller 4 are curved (at least predominantly) forwardly, that is, in the direction of rotation F of the impeller, the interconnection elements 13 are advantageously curved, in the projection in the frontal plane (Figure 3), (at least predominantly) rearwardly, that is, in the opposite direction to the direction of curvature of the impeller blades.

Figure 4 shows a variant _n which (in the frontal projection) the interconnection elements 13 of the duct are again curved (at least predominantly) rearwardly, but with angles of inclination of their edges which decrease as the radial distance from the axis increases and which, at the limit, are substantially zero in the vicinity of the outer annular element 1C. This solution reduces disturbance effects induced by the radial components of the air-flow generated by the fan.

In the ducts according to the invention, the interconnection elements 13 act basically as fixed flow-diverting stator blades and, as can be seen in Figures 5 and 6, preferably have a set angle a which is substantially constant or at most increases, preferably monotonically, from the inner annular element 11 towards the outer annular element 1C.

The ring of interconnection elements 13 is preferably disposed radially facing the outer portions of the blades 5 of the impeller 4 and preferably faces the portion disposed between about 35% and 100% of the radial distance along the blades 5.

The duct according to the invention achieves an appreciable reduction in the noise generated by the cooling unit in operation and an advantageous recovery of the kinetic energy of the air-flow induced by the electric fan.

Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined by the appended claims.
6. An air duct substantially as hereinbef ore described with reference to Figures 3, 5 and 6, or Figures 4, 5 and 6, of the accompanying drawings.

6 CLAIMS 1. An air duct for an electric fan, the fan comprising an impeller wheel with a plurality of blades which extend f rom a hub to which an electric drive motor is to be connected, and the duct comprising: an outer annular element which extends in the vicinity of the periphery of the blades of the impeller, at least one inner annular element coaxial with the outer annular element and with the impeller, and a plurality of interconnection elements which extend, spaced apart angularly, between the inner and outer annular elements, wherein the interconnection elements are shaped in a manner such that they can def lect the f low towards the axial direction, reducing the tangential component of the velocity of the air-flow urged through the region between the annular elements when the impeller is in operation.

2. An air duct according to claim 1, wherein at least radially outer portions of the blades of the impeller are curved, in a projection in a frontal plane, at least predominantly forwardly, in the direction of rotation, and wherein the interconnection elements are curved, in the projection in the frontal plane, at least predominantly rearwardly relative to the direction of curvature of the blades of the impeller.

3. An air duct according to either preceding claim, wherein the interconnection elements have a set angle which is constant, or at most increases, from the inner annular element towards the outer annular element.

4. An air duct according to claim 3, wherein any increase of the set angle is monotonic.

7 5. An air duct according to any preceding claim, wherein the plurality of interconnection elements f ace the portions of the blades of the impeller which are disposed between about 35% and 100% of the radial extent of the blades.