The present invention relates to portable hairdryer devices, and in particular it relates to a hairdryer axial fan adapted to be rotated at high speeds to generate an axial air jet. The invention also relates to a method for implementing such fan.

Portable hairdryers that are known and widespread on the market, intended both for professional and household use, are electrical devices provided with an outer casing commonly made of plastics provided with a handle and an air duct, within which an electric motor, a fan of centrifugal or axial type, connected to and rotated by the electric motor, and one or more electrical resistors for heating air are housed.

When the hairdryer is in use, i.e. the electric motor is supplied and the current flows through the heating electrical resistors, the fan is driven in rotation by the electric motor and generates, inside the casing and more precisely inside the air duct, an air flow which is sucked into the rear part of the hairdryer by means of a suction aperture, flows into the duct and outflows from a front dispensing aperture. The air flow passes through the heating electrical resistors which produce heat upon passage of the current as for Joule effect, thereby it heats up and outflows heated through the hairdryer dispensing aperture.

It is known that the prolonged use of a bulky and heavy hairdryer, in particular by professionals in the hairstyling field who keep upper limbs lifted and perform cyclically repetitive movements, can lead to harmful consequences on muscles and tendons of the hand-wrist-elbow-shoulder system, in some cases resulting in a disease becoming chronic. Medical studies have demonstrated in fact that almost 40% of hairdressers suffers from diseases in the musculoskeletal apparatus, in particular related to posture or to the biomechanical overload of upper limbs due to the prolonged use of the hairdryer ln order to reduce the occurrence of musculoskeletal apparatus diseases among hairdressers, in addition to cautions such as keeping the right posture while working and rotation of working tasks with higher or lower functional requirement, it is extremely important to use handy and light-weight hairdryers, with little or no burden on the hand- wrist-elbow- shoulder system.

The trend in the field is thus to keep reducing the overall size and weight of hairdryers without reducing the power driving the fan and generating the air flow, in other words not increasing the time required to dry hair.

To this end, in latest-generation hairdryers small-sized and light-weight electric motors are used, that are in any case capable of supplying the same power as traditional electric motors by means of rotation of fans at higher speeds so as to obtain the required air flows. Hairdryer fans, of centrifugal or axial type, are generally made of plastics, still in order to reduce the device overall weight.

However, in new hairdryers provided with high speed electric motors, due to high centrifugal forces (and internal mechanical tensions) deriving from high rotation speeds, fans cannot be made of plastics, by contrast it is required to use metal materials, in particular light, more robust and resistant metal alloys.

Fans used are preferably of the axial type and have a disk-shaped central body that radially supports a plurality of angularly spaced-out blades or suitably twisted to generate an axial air flow. In order to reduce inner mechanical stresses due to high rotation speeds and guarantee concurrently appropriate air flows and pressure, fans comprise a high number of small-sized blades, angularly close and partially overlapped in the axial direction.

Known fans are generally made of aluminium alloy by mechanical processing removing swarf from the full piece (milling), i.e. starting from an initial single block or piece of alloy. Due to the constructive complexity of fans with twisted, close and overlapped blades, this processing is particularly complex, time-consuming and very expensive.

Alternatively, fans can be made by die casting, though such process is very expensive as proper metal moulds and devices for injecting at high pressure the melt metal material inside such moulds must be constructed. Furthermore, particular metal alloys adapted for die casting must be used.

An object of the present invention is to improve axial fans, in particular made of metal, for portable hairdryers and methods for making such fans.

Another object is to provide a hairdryer axial fan made of metal alloy that is cost-effective and easy to make and at the same time robust and reliable, capable of rotating at high speed and generating high air flows.

One further object is to provide a method for rapidly, easily and cost-effectively making a hairdryer axial fan of metal alloy that is robust and reliable and capable of rotating at high speed.

In one first aspect of the invention it is provided a hairdryer axial fan according to claim 1. In one second aspect of the invention it is provided a method for making a hairdryer axial fan according to claim 8.

The invention will be better understood and implemented referring to the accompanying drawings illustrating an exemplary and non-limiting embodiment, wherein:

figure 1 is a plan view of the hairdryer fan of the invention;

figure 2 is a side view of the hairdryer fan of figure 1 ; figure 3 is a perspective view of the hairdryer fan of figure 1 ;

figures 4 to 6 are respectively plan, side and perspective views of a first blade element of the fan of figure 1 ;

figures 7 to 9 are respectively plan, side and perspective views of a second blade element of the fan of figure 1 ;

Referring to figures 1 to 9 the hairdryer axial fan 1 according to the invention is provided with a blading 2 to produce, when rotated about a longitudinal main axis X, an axial air flow, i.e. parallel to said main axis X. The hairdryer axial fan or fan 1 is arranged to be assembled on a portable hairdryer, driven in rotation by a high-speed rotation electric motor.

The fan 1 comprises a first blade element 3 provided with a first central disk 4 and with a plurality of first blades 5 that are twisted, extend radially from, and are angularly spaced-out along, a peripheral edge of the first central disk 4 and with at least a second blade element 13 provided with a second central disk 14 and with a plurality of second blades 15 that are twisted, extend radially from, and are angularly spaced-out along, a peripheral edge of the second central disk 14.

The first central disk 4 and the second central disk 14 are almost flat and respectively provided with a first central hole 7 and a second central hole 17 for mounting the blade elements 3, 13 on the shaft of an electric motor.

The first blade element 3 and the second blade element 13, illustrated in particular in figures 4 to 9, are axisymmetric elements i.e. symmetrical with respect to respective longitudinal axes XI, X2, these latter being orthogonal to the central disks 4, 14.

As illustrated in figures 1 to 3, in an assembled configuration A of the fan 1 of the invention the first blade element 3 and the second blade element 13 are mutually fixed so that the respective central disks 4, 14 abut and are coaxial, in particular along the main axis X, and so that each first blade 5 of the plurality of first blades 5 is inserted between two adjacent second blades 15 of the plurality of second blades 15 and vice versa. Thereby, the plurality of first blades 5 and the plurality of second blades 15 form the blading 2 of the fan 1. The central holes 7, 17 of the central disks 4, 14 are also coaxial in the assembled configuration A, to allow mounting the fan 1 on the shaft of a hairdryer electric motor.

The first blades 5 and second blades 15 are twisted i.e. they are bent with twisting by means of plastic deformation by overlapping a torsion stress and a bending stress, such that each section is rotated with respect to the adjacent section.

It must be noted that the twisting of the first and second blades 5, 15 allows to insert the first blades 5 between the second blades 15 and vice versa, since in a non-bent configuration wherein the blades are not twisted but they are plane and coplanar to respective central disks

4, 14, the first blades 5 and second blades 15 would overlap due to minimum spacing provided between a blade and the other one in each blade element 3, 13.

In the illustrated embodiment, each blade element 3, 13 comprises seven respective blades

5, 15 such as to make a fan 1 provided with fourteen blades, which could not be made on a single blade element, unless sizes are reduced.

The first blade element 3 and the second blade element 13 are in fact obtained by cutting, in particular shearing off, and subsequently bending a sheet metal, for instance a flat sheet metal of constant thickness, in particular a spring steel sheet. More precisely, the blade elements 3, 13 are obtained from the flat sheet of metal by means of a combined process of shearing off and bending, each of the blade elements 3, 13 comprising a respective central disk 4, 14 and a plurality of blades 5, 15. These latter are in particular made by cutting or shearing off and are thus suitably bent.

The vent 1 comprises fixing means 6, 16 arranged to fasten the first blade element 3 to the second blade element 13 in the assembled configuration A. More precisely, the fixing means

6, 16 comprise a plurality of hooks 6 made on one of the central disks, for example on the first central disk 4 of the first blade element 3, and a plurality of through apertures 16 made on the other of the aforesaid central disks, for example on the second central disk 14 of the second blade element 13. In the assembled configuration A the hooks 6 are inserted, in particular by force fitting, into respective through apertures 16, so as to tightly fasten the blade elements 3, 13 between them.

The hooks 6 are protrusions, for instance eyelet- or bridge-shaped, made by shearing off and plastically deforming the metal of the first central disk 4, in particular by means of punching. Such hooks 6, that protrude from an abutting wall 4a of the first central disk 4, are arranged angularly spaced-out about a first longitudinal axis XI of the first blade element 3.

The through apertures 16 are also made by shearing off the metal of the second central disk 4, in particular by means of punching, and have slightly lower dimensions than those of the hooks 6. Thereby, the hooks 6 can be inserted into the through apertures 16 only by force fitting, i.e. applying an established inserting force which guarantees stability and tightness to the connection between the blade elements 3, 13. The through apertures 16 are, for example, equal in number as hooks 6 and are arranged angularly spaced-out about a second longitudinal axis X2 of the second blade element 13.

In one variant of the hairdryer axial fan 1 of the invention that is not illustrated in the figures, it is provided a third blade element provided with a third central disk and with a plurality of third blades, that are twisted, extend radially from and are angularly spaced-out along, a peripheral edge of the third central disk. In the assembled configuration A of such a variant of the fan 1, the third blade element is fixed to the first and second blade elements 3, 13 such that the third central disk abuts and overlaps with the first central disk 4 or the second central disk 14, with each third blade inserted between one first blade 5 and one second blade 15 that are adjacent; the plurality of first blades 5, second blades 15 and third blades form the blading 2 of the hairdryer axial fan 1.

The hairdryer axial fan 1 of the invention formed by coupling and fixing at least two blade elements 3, 13 made of metal by means of shearing off and bending, is thus more cost- effective and easy to make than known axial fans obtained by mechanical processing with swarf removal or with die casting processes. Furthermore, as it is made of metal, the fan is robust and reliable, and it is capable of rotating at high speed to generate high air flows.

It must be noted that by joining and overlapping two or more blade elements 3, 13 it is possible to obtain an axial fan provided with a relevant number of blades 5, 15 to generate a high air flow.

The method according to the invention to make the hairdryer axial fan 1 described above and illustrated in figures 1 to 9 comprises:

cutting, in particular shearing off, a sheet metal, in particular a spring steel sheet, to obtain a first blade element 3 comprising a first central disk 4 and a plurality of first blades 5 that extend radially from, and are angularly spaced-out along, a peripheral edge of the aforesaid first central disk 4, and at least one second blade element 13 comprising a second central disk 14 and a plurality of second blades 15 that extend radially from, and are angularly spaced-out along, a peripheral edge of the aforesaid second central disk 14;

bending with twisting each blade of said plurality of first blades 5 and of second blades 15 with respect to the respective central disks 4, 14, in particular by means of deformation by overlapping a torsion stress and a bending stress;

fixing the first blade element 3 to the second blade element 13 in order to realize the hairdryer axial fan 1 so that the respective central disks 4, 14 abut and are almost coaxial along a main axis X of the fan 1 thereof and that each first blade 5 is inserted between two adjacent second blades 15 and vice-versa, the plurality of first blades 5 and the plurality of second blades 15 forming the blading 2 of the fan.

The method also provides that the steps of cutting and bending the sheet metal are performed in a same operation. The method comprises making fixing means 6, 16 by shearing off and/or punching on the first central disk 4 and on the second central disk 14, to fasten the first blade element 3 to the second blade element 13. In particular, said making comprises making a plurality of hooks 6 of the fixing means 6, 16 on the first central disk 4 and a plurality of through apertures 16 of the fixing means 6, 16 on the second central disk 14. Fixing the first blade element 3 to the second blade element 13 comprises inserting, in particular by force fitting, hooks 6 in respective through apertures 16.

The method provides to make the shearing off and/or punching for making the fixing means 6, 16 during said cutting the sheet metal.

Thanks to the method of the invention it is therefore possible to make rapidly, easily and cost-effectively a hairdryer axial fan 1 adapted to be used in combination with a high speed rotation electric motor in a portable hairdryer. It is in fact cost-effective to make the two blade elements 3, 13 of metal, provided with respective pluralities of twisted blades 5, 15 and with suitable hooking means 6, 16, by means of shearing off and bending processes. More precisely the first blades 5 of the first blade element 3 combined with the second blades

15 of the second blade element 13 make a blading 2 able to generate a high air flow. The hooking means 6, 16 comprising hooks 6 and corresponding through apertures 16 made by means of shearing off and deformation on central disks 4, 14, allow to mutually fasten and block the two blade elements 3, 13 in an assembled configuration A of the fan 1, which is robust and reliable, and capable of rotating at high speed.