“A HOT AIR FLOW GENERATOR, PREFERABLY A HAIRDRYER, HAND DRYER, ELECTRIC HEATER, OR PAINT REMOVER”

This invention relates to an air heating device for a hot air flow generator, preferably a hairdryer, hand dryer, electric heater, paint remover, or any device operating by Joule effect.

This invention also refers to a hot air flow generator, preferably a hairdryer, comprising said device and a method for assembling said heating device. Therefore, this invention finds its main application in the field of small household appliances and, more precisely, in the production and manufacture of the heating components to be inserted inside the blow duct, more preferably of a hairdryer.

For the sake of descriptive simplicity, explicit reference will be made below to hairdryers as the sector with the highest rate of development in recent years. However, where technically applicable, everything that is described with explicit reference to a hairdryer is also applicable, mutatis mutandis, to a different hot air flow generator operating by Joule effect.

The hairdryer sector, which for several years has seen little innovation with regard to the final product, has recently had a considerable innovative boost both from the point of view of technology and from the point of view of design.

In particular, new shapes of blow ducts have been developed, which differ from the classic tapered tubular body and have different and more attractive geometries.

A shape that is having particular success is the annular one, wherein the blow duct is not“trivially” delimited by a more or less cylindrical tubular duct, but extends annularly inside a chamber suitably delimited by a pair of concentric tubes.

This shape, in addition to allowing a particular and efficient air ejection, gives the product an attractive and distinctive appearance due to the “through” light passing through the main body of the appliance. A solution of this kind, however, brings with it considerable assembly problems, since there are many components to be connected, both mechanically and electrically, in a very limited space.

Moreover, increasing performance demands make it complicated for the manufacturer to find solutions that can be adapted to different hairdryers or even to different versions of the same hairdryer, with significant impact in terms of production costs and, therefore, competitiveness.

The purpose of this invention, therefore, is to provide an air heating device for a hot air flow generator, a hot air flow generator comprising said device and a method for assembling said heating device, which are capable of overcoming the above-mentioned drawbacks of the prior art.

In particular, the purpose of this invention is to provide an air heating device for a hot air flow generator that is both efficient and simple to assemble.

In addition, another purpose of this invention is to provide an air heating device for a versatile and cost-effective hot air flow generator.

In addition, one purpose of this invention is to provide a particularly versatile and efficient method for assembling said heating device.

Said purposes are achieved with an air heating device for a hairdryer having the features of one or more of the claims below.

In particular, the purposes of this invention are achieved with an air heating device for a hot air flow generator comprising an inner tubular support extending along a central axis between a first and a second axial end and provided with an outer surface.

A plurality of radial baffles, extending from said outer surface of the inner tubular support and angularly spaced apart from each other so as to define a plurality of angular sectors, is preferably provided.

The device preferably comprises a resistive coil provided with at least one corrugated wire helically extending about said inner tubular support, resting on said radial baffles, and defining a plurality of turns arranged in succession along the central axis. Each radial baffle preferably has a radially outer edge provided with a plurality of receiving grooves for said resistive wire arranged in axial succession.

One or more auxiliary devices (e.g. thermostat, thermistor, ionizer, or fuse, etc.) are also, preferably, provided; these are attached to said inner tubular support.

According to one aspect of the invention, the receiving grooves of the same turn formed on the outer edge of said radial baffles are placed at an increasing distance from said first or second axial end of the inner tubular support.

The arrangement of the grooves advantageously follows the helix angle of the design, thus improving the ease of assembly as much as the efficiency of the heating device.

With reference to each turn of the resistive coil, each receiving groove of a radial baffle is preferably axially offset from the receiving groove of the immediately following radial baffle by a step“p”.

This step“p” is preferably equal to: p = d ^* tan(P)

wherein:

- p is the step defining the axial offset between two receiving grooves of two successive radial baffles;

- d is the circumferential distance between said two successive radial baffles;

- b is the helix angle defining said resistive coil.

Moreover, the plurality of radial baffles preferably comprises a plurality of first baffles having the same geometry to each other and being fixed on said inner tubular support so that each first baffle is axially offset from the two first baffles adjacent to it (i.e. immediately preceding and following according to the circumferential direction).

In this regard, the plurality of first baffles preferably comprises at least one first proximal baffle, placed at a minimum distance from the first axial end of the inner tubular support, and one first distal baffle, placed at a maximum distance from said first axial end. The axial displacement“D” between the first proximal baffle and the first distal baffle is preferably quantified by the following formula:

D = a - p

wherein:

- D is the axial displacement between the first proximal baffle and the first distal baffle;

- a is the centre distance between two successive grooves of the radially outer edge of a first baffle;

- p is the step defining the axial offset between two receiving grooves of the same turn in two first successive baffles.

The heating device also preferably comprises at least one connector anchored to said inner tubular support and provided with a first end, radially protruding and connected to the resistive wire, and a second end that can be connected to a power source.

The plurality of radial baffles preferably comprises at least one second baffle, which is different from the first baffles, placed near said connector and provided with at least one first housing groove.

Said first housing groove is preferably shaped to divert the resistive wire towards the first end of the connector and spaced from the adjacent housing groove (i.e. immediately preceding/following along the axial direction) by a greater centre distance compared to the centre distance between said adjacent housing groove and the successive housing groove (i.e. distal from the first housing groove in relation to the adjacent housing groove).

The inner tubular support preferably has a plurality of axial grooves for receiving said radial baffles extending from an abutment shoulder placed at the first axial end. It should be noted that, the abutment shoulders preferably have different axial extensions depending on the axial position of the respective first or second baffle.

According to another aspect of this invention, alternative or complementary to those described above, the axial grooves comprise at least one first undercut made at said abutment shoulder and at least one second undercut made in an intermediate portion of the groove.

Each baffle is preferably provided, at a radially inner edge thereof, with a first and a second coupling portion coupled to said first and second undercut respectively.

In accordance with this aspect of the invention, the first coupling portion preferably comprises an axial protrusion shaped to define a forced coupling with said first undercut.

More preferably, the second coupling portion comprises an axial tongue slidably inserted in said second undercut.

More preferably, the radially inner edge of said radial baffles has a first axial section and a second axial section placed at different radial heights and separated by a notch defining said second undercut.

According to another aspect of this invention, alternative or complementary to those described above, the inner tubular support comprises a tubular portion having the above-mentioned plurality of axial grooves for receiving said radial baffles and extending axially between a first and a second end portion, the latter corresponding to said second axial end.

This tubular support also comprises an annular bottom member coupled to the first end portion of the tubular portion to define the first axial end of the inner tubular support and provided with a plurality of abutment shoulders, each positioned in axial alignment with a corresponding axial groove.

Thus the production of the two (plastic) components for moulding is, advantageously, simple, as well as economical, since the axial dimension of the abutment shoulders only affects the annular bottom member. The annular bottom member preferably comprises a plurality of axial mechanical invitations, each extending from a respective abutment shoulder and aligned with a respective axial groove to define an extension thereof.

The tubular portion and the annular bottom member of the inner tubular support are preferably reversibly coupled to each other by means of a quick coupling.

More preferably, this quick coupling comprises a hook axially protruding from said tubular portion and circumferentially interposed between two successive axial grooves and a seat produced in said annular bottom member and shaped to receive said hook and axially attach the annular bottom member and the tubular portion.

Even more preferably, the quick coupling comprises a plurality of hooks and a corresponding plurality of angularly spaced seats.

This also, advantageously, simplifies and speeds up the assembly of the inner tubular support.

The first end portion of the tubular portion and the annular bottom member preferably have respective pluralities of substantially U-shaped and two- by-two complementary notches to define through eyelets on the inner tubular support.

This, advantageously, simplifies the production of the mould for the tubular portion, making the process more economical.

Moreover, the heating device preferably comprises an outer tubular body made of insulating material and arranged coaxially to said inner tubular support about said resistive coil.

In this respect, the annular bottom member preferably comprises a plurality of radial arms angularly spaced apart from each other and abutted against said outer tubular body to prevent said outer tubular body from axially slipping off the first axial end of the inner tubular support.

This advantageously makes it easier to position the outer tubular body (insulating), which, in the assembly condition, is interposed between the body of the hairdryer (usually tapered at the end) and the radial arms.

In addition, each radial arm preferably defines an extension along a radial direction of a corresponding abutment shoulder, so that it is aligned with a respective radial baffle and minimises the size of an air passage section. According to another aspect of this invention, alternative or complementary to those described above, the heating device comprises a plurality of first connection terminals fixed to said inner tubular support, each provided with a first end electrically connected to said resistive coil and/or to said one or more auxiliary devices and a second free end.

A spacer ring, abutted against said first axial end of the inner tubular support and equipped with second terminals, each coupled to a corresponding first terminal, is preferably provided.

More preferably, there is a printed circuit board housed within said spacer ring and electrically connected to said second terminals.

Advantageously, this solution takes advantage of the presence of the spacer, making it an active component to rigidly connect the resistor and the printed circuit board (usually supplied/used by the hairdryer manufacturer).

This limits the number of wires and facilitates the connection of the device with the control electronics, making assembly quicker and easier.

The first terminals are preferably connected to the outer surface of the tubular support and the second terminals are placed on a radially outer surface of the spacer ring.

In order to facilitate the coupling between the two components, the first terminals axially protrude from said first axial end of the inner tubular support.

Moreover, the device preferably comprises a plastic support counter shaped to a radially internal cross-section of said spacer ring and shaped to fix the printed circuit board to said spacer ring.

In this way, the production of a plastic support dedicated to the specific shape of the printed circuit board, without the need for additional modifications to the other components of the resistor, is, advantageously, easy and economical.

These and other features, together with the advantages related thereto, will become more apparent from the following illustrative, and therefore non-limiting, description of a preferred, and thus non-exclusive, embodiment of an air heating device for a hot air flow generator, as illustrated in the accompanying figures, wherein:

- Figure 1 shows a perspective view of an air heating device for a hot air flow generator according to this invention, in a first embodiment;

- Figure 2 shows a perspective view of the heating device in Figure 1 , with some parts removed to highlight others;

- Figure 3 shows a side view of a heating device in Figure 1 , with some parts removed to highlight others;

- Figure 4 schematically shows, and flatly, the axial arrangement of the radial baffles of the heating device in Figure 1 ;

- Figure 5 shows a cross-section view along the section line V-V in Figure 3;

- Figures 6a and 6b schematically show the assembly of a radial baffle in two successive steps;

- Figure 7a shows an exploded perspective view of an early embodiment of an inner tubular support for a heating device according to this invention;

- Figures 7b and 7c show, respectively, a perspective view of the inner tubular support in Figure 7a in the assembly configuration and a detail of it in cross-section;

- Figures 8a and 8b respectively show an exploded perspective view and a perspective view in the assembly configuration of a second embodiment of an inner tubular support for a heating device according to this invention;

- Figures 9a, 9b, and 9c show successive steps for assembling a heating device according to this invention with a printed circuit board according to a first embodiment; - Figures 10a, 10b, and 10c show successive steps for assembly a heating device according to this invention with a printed circuit board according to a second embodiment;

- Figures 1 1 a, 1 1 b, and 1 1 c show successive steps for assembling a component of the heating device according to this invention.

With reference to the accompanying figures, the reference number 1 indicates an air heating device for a hairdryer according to this invention. For the sake of descriptive simplicity, explicit reference will be made below to hairdryers as the sector with the highest rate of development in recent years. Flowever, where technically applicable, everything that is described with explicit reference to a hairdryer is also applicable, mutatis mutandis, to a different hot air flow generator operating by Joule effect.

The heating device 1 is of the type commonly defined as“resistor” in that it comprises, in addition to a support (better described below), a resistive coil that, when an electric current passes through it, overheats so as to raise the temperature of an air flow hitting it.

In general, therefore, the air heating device 1 comprises a support about which at least one resistive wire is wound, which is hit, in use, by an air flow generated by ventilation/blowing means, operatively placed upstream, in order to raise its temperature.

With reference to this invention, in particular, the device 1 comprises an inner tubular support 2, from which a plurality of radial baffles 3 branch out, about which a resistive coil 4, provided with at least one resistive wire 4a (preferably two parallel to each other), is wound.

The inner tubular support 2 is preferably made of electrically and thermally insulating material, more preferably of plastic.

Instead, the radial baffles 3 are made of an electrical insulating and thermal resistant material, for example mica or another antistatic material. Moreover, in order to maximise heat transfer, the resistive wire 4a forming the resistive coil 4 is shaped according to at least one predetermined waveform, which can comprise sinusoidal and/or zig-zag and/or square and/or spiral undulations, and, more generally, undulations of any form.

In the illustrated embodiment, each turn S of the coil 4 extends circumferentially about the inner tubular support 2 according to an undulating pattern defining a succession of peaks and grooves.

Preferably, but not necessarily, the device 1 may also comprise an outer tubular body 19, also made of insulating material and arranged coaxially to the inner tubular support 2 about the resistive coil 4.

Structurally, the inner tubular support 2 extends along a central axis“A” between a first 2a and a second axial end 2b and is provided with an outer surface 2c.

The radial baffles 3 (or thin plates) extend from said outer surface 2c of the inner tubular support 2 and are angularly spaced apart from each other about the inner tubular support 2 so as to define a plurality of angular sectors.

Each radial baffle 3 axially extends (i.e. along the central axis“A”) between a first 3c and a second end 3d and has a radially outer edge 3a and a radially inner edge 3b.

The radially outer edge 3a is provided with a plurality of receiving grooves 5 for the resistive wire 4a arranged in axial succession, so as to enable a precise positioning of the same during the production of the resistive coil 4. In this respect, in fact, the resistive wire 4a helically extends about said inner tubular support 2, resting on the radially outer edge of the radial baffles 3, at the grooves 5, and defines a plurality of turns S arranged in succession along the central axis A.

According to one aspect of this invention, the receiving grooves 5 of the same turn S formed on the outer edge 3a of said radial baffles 3 are placed at an increasing distance from said first 2a or second axial end 2b of the inner tubular support 2.

In other words, a receiving groove 5 formed on the outer edge 3a of a radial baffle 3 is placed at an axial distance from the first axial end 2a of the inner tubular support 2 that is greater (or lesser) than the receiving groove 5 of the same turn S of the resistive coil 4 formed on the radial baffle 3 immediately preceding (or following) in accordance with a helix angle b with which the resistive coil 4 extends. It should be noted that the expression “immediately preceding (or following)” refers to the circumferential direction or the direction of the wire’s winding.

Thus, the winding of the resistive wire 4a about the tubular support 2 is advantageously simplified and highly precise, reducing defects and limiting the stress zones on the wire itself.

With reference, again, to each turn S of the resistive coil 4, each receiving groove 5 of a radial baffle 3 is preferably axially offset from the receiving groove 5 of the immediately following radial baffle 3 by a step“p” equal to:

p = d ^* tan(P)

wherein:

- p is the step defining the axial offset between two receiving grooves 5 of two successive radial baffles;

- d is the circumferential distance between said two successive radial baffles;

- b is the helix angle defining said resistive coil 4.

It is clear, therefore, that the arrangement of the receiving grooves 5 is consistent with the helix angle b of the design, maximising the quality of the product.

In order to make the production of the component economical, the radial baffles 3 preferably comprise a plurality of first baffles 6 having the same geometry.

In other words, the first baffles 6 have the same shape and the same arrangement as the receiving grooves 5, since they are preferably produced from the same mould/design.

These first baffles 6 are fixed on the inner tubular support 2, or on its outer surface 2c, so that each first baffle 6 is axially offset compared to the two first adjacent baffles 6. The term “adjacent” refers, again, to the circumferential or winding direction of the resistive wire 4a; therefore, the term“adjacent” is in this context synonymous with the expression “immediately preceding or following” used previously.

According to this (preferable but optional) aspect of the invention, therefore, the offset of the receiving grooves 5 in successive baffles is obtained by varying the axial position of the baffles in an appropriate way. More specifically, the first baffles 6 comprise at least a first proximal baffle 6’, placed at a minimum distance from the first axial end 2a of the inner tubular support 2, and a first distal baffle 6”, placed at a maximum distance from said first axial end 2a.

The axial displacement D between the first proximal baffle 6’ and the first distal baffle 6” is preferably quantified by the following formula:

D = a - p

wherein:

- D is the axial displacement between the first proximal baffle 6’ and the first distal baffle 6”;

- a is the centre distance between two successive grooves of the radially outer edge 3a of a first baffle 6;

- p is the step defining the axial offset between two receiving grooves 5 of the same turn in two first successive baffles.

The maximum axial displacement between the radial baffles 3, and, in particular, between the first baffles 6, is, therefore, preferably less than the centre distance between two successive grooves; once this maximum displacement is reached, in fact, the successive baffle is positioned again as the first proximal baffle 6’, taking advantage of the succession of axial grooves.

Observing the arrangement of the first baffles 6 on a plane (Figure 4), it is therefore evident that they are arranged according to a triangular wave, first increasing linearly (in several steps) from the first proximal baffle 6’ to the first distal baffle 6” and then decreasing directly from the axial height of the first distal baffle 6” to that of the first proximal baffle 6’.

This advantageously and significantly limits the distance between the first proximal baffle 6’ and the first distal baffle 6”, making it easier to assemble and design the device.

In this respect, it should be noted that the inner tubular support 2 preferably has a plurality of axial grooves 9 for receiving said radial baffles 3 made on the outer surface 2c and extending from an abutment shoulder 10 placed at the first axial end 2a.

The abutment shoulders 10 preferably have different axial extensions depending on the axial position of the corresponding first baffle 6.

This is particularly advantageous during the production of components, as it is sufficient to design/size the abutment shoulders 10 (in plastic material) without needing to modify or differentiate the radial baffles.

It should be noted that to connect the resistive wire 4b (or resistive wires) to the power electronics, the heating device 1 comprises at least one connector 7 anchored to said inner tubular support 2. There are, preferably, at least two connectors 7 arranged at the first 2a and the second axial end 2b, respectively, of the inner tubular support to connect to a first 4b and a second end 4c of the resistive wire 4a, respectively.

In the preferred embodiment, there are four connectors 7, arranged in pairs at the first 2a and second axial end 2b of the inner tubular support 2. More precisely, in the embodiment illustrated, the two connectors 7 placed at the second axial end 2b of the inner tubular support 2 are made of a single component.

Structurally, each connector 7 comprises a first end 7a radially protruding and connected to the resistive wire 4a, and a second end 7b that can be connected to a power source.

The radial baffles 3 preferably comprise at least one second baffle 8 (preferably at least two), which is different to the first baffles 6 and placed near said connector 7. The second baffle 8 (or the second baffles 8) is also anchored to the inner tubular support 2 at a corresponding axial groove 9 and in abutment on a corresponding abutment shoulder 10 that is suitably sized.

The second baffle 8 is preferably provided with at least one housing groove 5’ shaped to divert the resistive wire 4a towards the first end 7a of the connector 7 and spaced apart from the adjacent housing groove 5” at a greater centre distance than the centre distance between said adjacent housing groove 5” and the successive housing groove 5’”.

This first groove 5’ is the housing groove of the last (or first) turn S of the resistive coil 4, the end 4b, 4c of which is coupled to the connector 7.

Thus, the second baffle 8 is shaped so that near one axial end (or both) thereof, the centre distance between two grooves (first groove 5’ and adjacent groove 5”) is greater than the centre distance“a” between the other grooves (successive grooves 5’).

Advantageously, this makes it possible to divert the end portion of the resistive wire 4a by an angle greater than the helix angle b, thus creating a greater axial space between two successive turns that is useful for enabling the automated clamping of the wire.

In this respect, the second baffle 8 is preferably placed near the connector 7 (or the connectors 7) placed at the second axial end 2b of the inner tubular support 2.

In the preferred embodiment, the device 1 comprises two second baffles 8 arranged in succession upstream of the connector 7, with reference to a resistive wire 4a winding direction.

Similarly, the first groove 5’ is preferably made near that of the second axial end 2b, so as to favour the“diverting” of the resistive wire towards the connector 7.

This arrangement advantageously facilitates the clamping of the resistive wire 4a to the connector 7 at the end of the winding. It should be noted that, in embodiments that require winding the resistive wire 4a beginning from the second axial end 2b towards the first axial end 2a of the tubular support, the arrangement of the second baffles 8 could be reversed.

According to another aspect of the invention (alternative or complementary to the preceding), in order to ensure that the assembly of the radial baffles 3 (first 6 and/or second 8) is simple and reliable, the axial grooves 9 comprise at least one first undercut 1 1 a made at said abutment shoulder 10 and at least one second undercut 1 1 b made in an intermediate or end portion of the groove 9.

In this respect, each baffle 3 is provided, on the radially inner edge 3b thereof, with a first 12 and a second coupling portion 13 coupled respectively to said first 1 1 a and second undercut 1 1 b.

Since both undercuts 1 1 a, 1 1 b are of the“axial” type, the coupling with the first 12 and the second coupling portion 13 of the baffle prevents a radial detachment of the same from the inner tubular support 2.

Moreover, the first coupling portion 12 preferably comprises an axial protrusion 12a shaped to define a forced coupling to said first undercut 1 1 a.

In this way, the coupling is, advantageously, also able to counteract the axial movement of the baffle 3 in relation to the tubular support 2.

In the preferred embodiment, the axial protrusion 12a has a tapered shape to define a cone clamping coupling with the first undercut 1 1 a.

The second coupling portion 13 instead comprises an axial tongue 13a slidably inserted in said second undercut 1 1 b, preferably freely (i.e. unforced coupling).

In addition, the portion of the radially inner edge 13 between the first 12 and the second coupling portion 13 is preferably coupled in the axial groove 9 with clearance.

In the embodiment illustrated (for example in Figure 5), the radially inner edge 3b of the radial baffles 3 has a first axial section 3b’ and a second axial section 3b” located at different radial heights and separated by a notch counter-shaped to said second undercut 1 1 b.

In this way, the baffle 3 is, advantageously, easier to produce and the device 1 is easier to assemble.

In this respect, in fact, the presence of the two undercuts 1 1 a, 11 b shaped thus makes it possible to assemble the baffles 3 with the inner tubular support 2 according to a more conservative procedure for the components and in the same reliable way.

In fact, in the embodiment in accordance with this aspect of the invention, the assembly procedure, which normally involves a highly forced axial insertion over the entire length of the baffle, involves:

- placing each radial baffle 3 in a radially outer position and aligned with a respective axial groove 9;

- inserting the radially inner edge 3b of each radial baffle 3 in the respective axial groove 9 according to a radial insertion direction“B”;

- moving each radial baffle 3 along an axial locking direction C until said abutment shoulder 10 is reached and, preferably, until the creation of said forced coupling between the first undercut 1 1 a and the first coupling portion 12;

- helically winding said resistive wire 4a about said inner tubular support 3 resting on the receiving grooves 5 of said radial baffles 3.

According to another aspect of the invention (alternative or complementary to those described above), the inner tubular support 2 is made by means of coupling two components.

Therefore, the inner tubular support 2 preferably comprises a tubular portion 14 and an annular bottom member 15 axially coupled together.

The tubular portion 14 has said plurality of axial grooves 9 and extends axially between a first 14a and a second end portion 14b, the latter corresponding to said second axial end 2b.

The annular bottom member 15 is coupled to the first end portion 14a of the tubular portion 14 to define the first axial end 2a of the inner tubular support 2 and is provided with a plurality of abutment shoulders 10, each positioned in axial alignment with a corresponding axial groove 9.

The annular bottom member 15 preferably comprises a plurality of axial mechanical invitations 15a, each extending from a corresponding abutment shoulder 10 and aligned with a corresponding axial groove 9 to define an extension thereof.

Advantageously, thanks to the bi-component tubular support, it is clear that any modification to the axial dimensions of the abutment shoulders 10 only impacts the shape of the annular bottom member 15, enabling the manufacturer maximum flexibility in varying design specifications.

The tubular portion 14 and the annular bottom member 15 of the inner tubular support 2 are preferably reversibly coupled to each other by means of a quick coupling 16, more preferably of the axial snap type.

In the embodiment illustrated (see for example Figures 7a, 7b, and 7c) the quick coupling 16 comprises an axially protruding (flexible) hook 16a and a receiving seat 16b of the same.

The quick coupling 16 preferably comprises a plurality of hooks 16a and a corresponding plurality of seats 16b that are angularly spaced apart from each other.

More specifically, the hook 16a is made in the tubular portion 14 and protrudes from the first end portion 14a and is circumferentially interposed between two successive axial grooves 9.

The seat 16b is made in the annular bottom member 15 and is shaped to receive said hook 16a and axially attach the annular bottom member 15 and the tubular portion 14.

Moreover, the first end portion 14a of the tubular portion 14, and the annular bottom member 15 preferably have respective pluralities of substantially U-shaped and two-by-two complementary notches 17 to define through eyelets 18 on the inner tubular support 2.

Advantageously, this makes it significantly easier to make the eyelets and the shape of the mould for producing the tubular portion 14 and the annular bottom member 15.

According to another aspect of the invention, complementary or alternative to the previous ones, the first axial end 2a of the inner tubular support 2 has a plurality of radial arms 20 angularly spaced apart from each other and abutted against said outer tubular body 19 to prevent said outer tubular body 19 axially slipping off said first axial end 2a.

This is particularly advantageous during assembly, as it attaches the only remaining degree of freedom to the outer tubular body 19 without the need for additional components or shoulders in the body of the hot air flow generator.

The radial arms 20 therefore have a greater radial extension than the baffles 3, so as to intercept the outer tubular body 19.

Each radial arm 20 preferably defines an extension along a radial direction of a corresponding abutment shoulder 10, so that it is aligned with a respective radial baffle 3 and minimises the size of an air passage section. In the preferred embodiment, illustrated for example in Figure 8a, 8b, the radial arms 20 are made of a single piece with the annular bottom member 15.

It should be noted that the heating device 1 preferably comprises one or more auxiliary devices 21 a, 21 b electrically connected to said winding. Such auxiliary devices may be a thermostat 21 a, a fuse 21 b, as well as, for example, an ionizing tip or a thermistor.

With reference to the thermostat 21 a and the fuse 21 b in particular, these devices are arranged electrically upstream of the resistive coil 4, in order to enable an interruption in the current flow before it passes through the resistive wire 4a.

The thermal fuse 21 b is preferably calibrated (with temperatures from 70°C to 260°C) to prevent excessive temperatures in abnormal operating conditions.

The thermostat 21 a, on the other hand, is preferably calibrated (with temperatures from 60°C to 170°C) to open the contact, in a reversible manner, when a temperature limit value is exceeded.

The fuse 21 b and the thermostat 21 a are preferably housed respectively in their respective angular sectors, preferably adjacent and separated from each other by a shared radial baffle 3.

In the preferred embodiment, the inner tubular support 2 has, at said angular sectors, respective slots for receiving the fuse 21 b and/or the thermostat 21 a.

This slot enables at least part of the thickness of the fuse 21 b or of the thermostat 21 b to be embedded in the inner tubular support 2, thus reducing its radial overall size within the respective angular sector.

According to another aspect of the invention, which is also complementary or alternative to those described above, the heating device 1 has a dedicated circuit 22 (illustrated in Figure 1 1 a) that, by means of suitable metallic bridge 22a, connects these devices with the resistive coil 4 (in addition to with each other).

This circuit 22 preferably has at least three metallic bridges 22a respectively connecting:

- a first electrical connection terminal with the thermostat 21 a;

- the thermostat 21 a with the fuse 21 b;

- the fuse 21 a with a second electrical connection terminal.

The first metallic bridge 22a’ is preferably defined by a connector fixed to the inner tubular support 2 and comprising a first end, defining said first electrical connection terminal, and a second end coupled to the thermostat 21 a.

The second metallic bridge 22a” is defined by a metallic band extending between a first and a second end coupled respectively with the thermostat 21 a and the fuse 21 b.

The metallic band preferably has at least one longitudinal section, parallel to the central axis“A”, and at least one section transverse to said central axis“A”.

The third metallic bridge 22a” is defined by another metallic band extending between a first end coupled with the fuse 21 b (and with the connector 7) and a second end defined by a connector.

The circuit 22, including the metallic bridges 22a, the fuse 21 b, and the thermostat 21 a, is preferably entirely fixed to the outer surface 2c of the inner tubular support 2.

Therefore, no component of the circuit 22 is arranged/coupled directly to the inner surface of the inner tubular support 2.

More preferably, this circuit 22 is pre-assembled and fixed to the inner tubular support 2 prior to the application of the baffles 3.

In this respect, at least the transverse section of the metallic band, defining the second metallic bridge 22a”, preferably transversely crosses a corresponding radial baffle 3.

In the preferred embodiment, therefore, the plurality of baffles 3 comprises a third baffle 30 (Figure 11 c) having, on the radially inner edge 30b thereof, a notch 31 defining a crossing span for said transverse section. Advantageously, this makes the assembly of the heating device 1 much simpler and more automated, since no internal work is required on the inner tubular support 2.

According to another aspect of this invention, which is also complementary or alternative to those described above, the heating device 1 comprises a plurality of first connection terminals 23 fixed to said inner tubular support 2a, each provided with a first end 23a electrically connected to said resistive coil 4 or to said one or more auxiliary devices 21 , 22 and to a second free end 23b.

Preferably, the first terminals 23 are partly defined by connectors 7 (or by their second end 7b) and/or by said first and second metallic bridge 22a connection terminals of the circuit 22.

In accordance with this aspect of the invention, the heating device 1 also comprises a spacer ring 24 abutted against the first axial end 2a of the inner tubular support 2 and equipped with second terminals 25, each coupled to a corresponding first terminal 23.

These second terminals 25 are, in turn, placed in electrical connection with a printed circuit 26 anchored to said spacer ring 24, preferably in a radially inner position inside it. In this respect, it should be noted that, the printed circuit board 26 is preferably fixed on the spacer ring 25 by means of one or more gripping or support portions 27.

In certain embodiments (Figures 10a, 10b, and 10c), the gripping and support portions have axial guide rails 27a and one or more holding clamps 27b for the printed circuit board 26. In this embodiment, the printed circuit board has one or more receiving seats for the holding clamps 27b.

In this respect, it should be noted that the embodiment described here requires that the printed circuit board 26 extends away from the spacer ring 24 inside the inner tubular support 2.

Alternatively, with reference, for example, to the embodiment in Figures 9a, 9b, and 9c, the gripping and support portions may have a peripheral shoulder 27c for receiving the printed circuit board 26 with coplanar orientation to the spacer ring 24.

In this embodiment, the radially inner surface of the spacer ring 24 has holding tabs 27d designed to keep the circuit abutted against the shoulder 27c.

It should be noted that, regardless of the type of spacer ring-electrical circuit connection, the spacer ring 24 is preferably coupled to the inner tubular support 2 using quick coupling means 29.

In the embodiment illustrated, these quick coupling means 29 comprise a coupling pin 29a snap-coupled into a slot 29b. The coupling pin 29a is preferably made in the inner tubular support 2, more preferably axially protruding from the annular bottom member 15 (or the first axial end 2a).

In accordance with this, the slot 29b is preferably made on one side of the spacer ring 24.

Alternatively, the coupling pin could be shaped to define a bayonet coupling (i.e. a coupling following an axial movement and rotation) between the inner tubular support 2 and the spacer ring 24.

From an electrical point of view, the first terminals 23 and the second terminals 25 are preferably coupled by means of a male-female coupling. More preferably, the first terminals 23 are male terminals and the second terminals 25 are female terminals.

This clearly significantly simplifies assembly, making the process highly automated.

In the preferred embodiments, the first terminals 23 are connected to the outer surface 2c of the tubular support 2 and the second terminals 25 are placed on a radially outer surface 24a of the spacer ring 24.

In some embodiments, the first terminals 23 axially protrude from said first axial end 2a of the inner tubular support 2 and are axially coupled to the second terminals 25 of the spacer ring 24.

Alternatively, however, in accordance with the type of mechanical coupling, the shape of the first and second terminals could also be such as to determine the electrical connection following a rotation between the components.

The invention achieves its intended purposes and significant advantages are thus obtained.

In fact, the provision of a heating device with radial baffles (or thin plates) at least partially equal to each other and axially offset makes it economical for the manufacturer to produce and, at the same time, in no way compromises its quality.

Furthermore, the possibility of coupling the baffles with the inner support without necessarily moving them axially along a groove in forced coupling reduces defects and undoubtedly improves product quality.

Moreover, the use of an bi-component and plastic inner tubular support makes it possible to easily modulate the design changes to be made to the product and, at the same time, makes the step for moulding the material easier.

The provision of a pre-assembled circuit containing the auxiliary devices and the metallic connection bridges undoubtedly facilitates the assembly of the device, making it particularly suitable for being inserted into an automated/robotised assembly process.

In this respect, the use of one or more second baffles to be angularly positioned near the connectors (or terminals) to widen the space between the last two turns of the winding is also of particular interest; this, in fact, makes the clamping of the resistive wire in the terminal less critical for an automatic manipulator.

Furthermore, the presence of an interface ring between the connectors (or terminals) on the support side and the printed circuit board driving the device is particularly interesting, especially in light of the fact that the spacer ring thus designed can be dedicated to the specific shape of the circuit and also adapted to the body of the hairdryer.