ELECTRIC FAN

Abstract

An electric fan, for cooling a heat exchanger of a motor vehicle, has an electric motor including a rotor and a stator, and an axial impeller including a central hub from which a plurality of blades extends. The hub is connected to the rotor at a number of connecting points. At each connecting point, the hub of the impeller is connected to the rotor by means of a respective connecting device including a resilient vibration damper.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Utility Model Application No. TO 2014 U 000003 filed in Italy on Jan. 10, 2014, the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to an electric fan and in particular, to a cooling fan for a heat exchanger of a motor vehicle.

BACKGROUND OF THE INVENTION

More specifically, the invention proposes an electric fan of the type comprising: an electric motor, including a rotor and a stator, and an axial impeller, including a central hub from which a plurality of blades extends, the huh being connected to the rotor of the motor at one or more connecting points or areas.

In operation, the electric motor of an electric fan of this type generates considerable vibration, which is transmitted to the impeller and causes the generation of acoustic noise which is rather annoying to the human ear, particularly at low speeds.

SUMMARY OF THE INVENTION

Hence there is a desire for an electric fan of this type, made in such a way as to overcome the aforementioned drawback of electric fans according to the prior art.

This is achieved by the present invention with an electric fan of the type specified above, in which, at each of the aforesaid one or more connecting points or areas, the impeller hub is connected to the rotor of the electric motor by means of a respective connecting device including a resilient vibration damper.

Accordingly, in one aspect thereof, the present invention provides an electric fan, for a heat exchanger of a motor vehicle, comprising: an electric motor including a rotor and a stator; and an axial impeller including a central huh from which a plurality of blades extends, the hub being connected to the rotor of said motor at one or more connecting points or areas, wherein at these one or more connecting points or areas, the hub of the impeller is connected to the rotor of the electric motor by means of a respective connecting device including a resilient vibration damper.

Preferably, the hub of the impeller has a substantially bowl-like shape, with an end wall connected to an annular lateral wall which is at least approximately cylindrical, and wherein the rotor of the electric motor has a crown which extends inside the hub of the impeller, near the end wall of said hub, to which it is connected by means of a plurality of said connecting devices including respective resilient vibration dampers.

Preferably, each of these one or more connecting devices comprises an annular damping member of resilient material, positioned in a through opening of the hub and penetrated by a fastening member for fastening the hub to the rotor of the motor.

Preferably, the resilient material is an elastomeric material.

Preferably, a tubular element of essentially rigid material, is interposed between each damping member and the corresponding fastening member.

Preferably, the tubular element is of a metallic material.

Preferably, the fastening member is a screw or bolt having an end head, and said rigid tubular element has at one end a flange-like formation interposed between the head of the corresponding screw or bolt and said damping member.

Preferably, the or each resilient vibration damper is in the form of a cylindrical ring, and has an outer peripheral groove that engages with an edge of said through opening of the hub of the impeller.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to figures of the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same reference numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below.

FIG. 1 is a perspective front elevation view of an electric cooling fan according to the invention;

FIG. 2 is a partial, perspective view, on an enlarged scale, which shows, in particular, the hub of the impeller of FIG. 1; and

FIG. 3 is a partial sectional view taken along line III-III of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, an electric fan according to the present invention is indicated as a whole by 1. The electric fan 1 comprises, in a known way, a substantially plate-like supporting structure or cowl 2, having a main circular opening 3 in which an impeller, indicated as a whole by 4, is rotatably mounted. The impeller 4 is connected to the rotor 8 of an electric motor which is not visible in FIGS. 1 and 2, but is partially illustrated in FIG. 3, where it is indicated as a whole by 5.

The electric motor 5 comprises a stator 6, fastened in a known way to the supporting structure or cowl 2, for example by means of a plurality of spokes 7 as shown in FIG. 1. The electric motor 5 also comprises a rotor 8, including an axial end surface or crown.

The impeller 4 comprises a central hub 9 from which a plurality of curved blades 10 extends, the outermost ends of which are joined to a peripheral ring 11 (FIG. 1). The hub 9 of the impeller 4 is connected to the rotor 8 of the electric motor 5 at one or more connecting points or areas.

In the embodiment illustrated by way of example in the drawings, the hub 9 is connected to the crown of the rotor 8 of the motor 5 at three connecting points or areas, indicated by 12, located at the same distance d from the axis X-X of the impeller (FIG. 3).

In the illustrated embodiment, the hub 9 of the impeller 4 has a substantially bowl-like shape, with an end wall 9a connected to an annular lateral wall 9b which is at least approximately cylindrical. The crown of the rotor 8 of the electric motor 5 extends inside the hub 9, near the end wall 9a of the latter, to which it is connected at the aforesaid three connecting points or areas 12 by means of devices 13 including respective resilient vibration dampers, which are described more fully below.

With particular reference to FIG. 3, each connecting device 13 comprises an annular damping member 14 made of resilient material, preferably an elastomeric material (vulcanized rubber). The damping member 13 is positioned in a through opening 9c of the end wall 9a of the hub 9 of the impeller. The damping member 14 essentially takes the form of a cylindrical ring, and in its axially intermediate part it has an outer peripheral groove 14a in which the edge of the through opening 9c of the hub 9 of the impeller 4 is engaged.

The damping member 14 is penetrated by a corresponding member 15 for fastening the impeller to the rotor crown 8 of the electric driving motor 5. The fastening member 15 is, for example, a screw or a bolt, having an end head 15a. Between the annular damping member 14 and the screw or bolt 15 there is interposed a tubular element 16 of essentially rigid material, for example a metallic material. The rigid tubular element 16 conveniently has a flange-like end formation 16a, interposed between the head 15a of the screw or bolt 15 and the adjacent end of the annular damping member 14.

The threaded shank of the screw or bolt 15 engages in a correspondingly threaded opening in the crown of the rotor 8.

Tests conducted by the applicant have demonstrated that the use of the solution according to the present invention provides a noticeable reduction, of the order of 10 dBA or more, in the acoustic noise generated, particularly in the range from about 100 Hz to 1 kHz.

In the description and claims of the present application, each of the verbs “comprise”, “include”, “contain” and “have”, and variations thereof, are used in an inclusive sense, to specify the presence of the stated item or feature but do not preclude the presence of additional items or features.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of example only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims.

Claims

1. Electric fan, for a heat exchanger of a motor vehicle, comprising:

an electric motor including a rotor and a stator; and

an axial impeller including a central hub from which a plurality of blades extends, the hub being connected to the rotor of said motor at one or more connecting points or areas,

wherein at these one or more connecting points or areas, the hub of the impeller is connected to the rotor of the electric motor by means of a respective connecting device including a resilient vibration damper.

2. The electric fan of claim 1, wherein the hub of the impeller has a substantially bowl-like shape, with an end wall connected to an annular lateral wall which is at least approximately cylindrical, and wherein the rotor of the electric motor has a crown which extends inside the hub of the impeller, near the end wall of said hub, to which it is connected by means of a plurality of said connecting devices including respective resilient vibration dampers.

3. The electric fan of claim 1, wherein each of these one or more connecting devices comprises an annular damping member of resilient material, positioned in a through opening of the hub and penetrated by a fastening member for fastening the hub to the rotor of the motor.

4. The electric fan of claim 3, wherein each damping member is of elastomeric material.

5. The electric fan of claim 3, wherein a tubular element of essentially rigid material, is interposed between the damping member and the corresponding fastening member.

6. The electric fan of claim 5, wherein the tubular element is of a metallic material.

7. The electric fan of claim 5, wherein said fastening member is a screw or bolt having an end head, and said rigid tubular element has at one end a flange-like formation interposed between the head of the corresponding screw or bolt and said damping member.

8. The electric fan of claim 3, wherein the or each resilient vibration damper is in the form of a cylindrical ring, and has an outer peripheral groove that engages with an edge of said through opening of the hub of the impeller.