Propeller for blowing device comprising radial channels for air flow

Abstract

The present invention relates to a propeller (10) for a blowing device, configured to be driven in rotation about a longitudinal axis (A), the propeller comprising: - a proximal wall (4) defining an inlet opening (40) admitting an airflow directed along the longitudinal axis (A), - a plurality of air passage channels (3) in fluidic communication with the inlet opening (40), said air passage channels (3) being positioned around the longitudinal axis (A), each air passage channel (3) extending radially between an inlet end and an outlet end, the outlet end having an outlet cross-section (34) having a maximum dimension parallel to the longitudinal axis (A) greater than or equal to 4 millimeters. The present invention further relates to a blowing device, preferably a hair dryer or a vacuum cleaner, comprising such a propeller.

Description

DOMAINE DE L'INVENTION

[0001] The invention falls within the field of mechanical design of electric blowing devices, and in particular domestic devices dedicated to hairdressing, such as hair dryers in particular.

[0002] The invention relates on the one hand to a rotating part for a blowing device comprising air passage channels, and on the other hand to a blowing device comprising such a rotating part. ETAT DE LA TECHNIQUE

[0003] Many household fan heaters incorporate a rotating part to produce a radial airflow inside the unit. The rotating part (propeller) is, for example, driven by an electric motor built into the unit.

[0004] Rotating parts like these are used in devices such as hair dryers to produce an outgoing airflow. A hair dryer typically consists of a handle held by the user and a longitudinal section, usually perpendicular to the handle, for air circulation. The airflow emerging from this longitudinal section is usually heated by a heating element.

[0005] In state-of-the-art hair dryers, the airflow is generated by a rotating propeller-type part that moves the air from an air inlet area to an air outlet area.

[0006] Rotating parts of the aforementioned type can also be included in other household appliances such as vacuum cleaners, extractor hoods, etc.

[0007] A known type of rotating part is a propeller comprising a plurality of blades regularly distributed around its periphery, and exhibiting rotational symmetry. Such a propeller is, for example, described in international application WO 2017 / 017330 A1.

[0008] The propeller in this document has the advantage of a simple mechanical structure. However, such a propeller can be a significant source of noise during the operation of blower devices.

[0009] Noise is primarily caused by airflow. The volume of air set in motion between two blades collides with adjacent fixed components, particularly the stator vanes. Other examples of fixed components of the hairdryer that can interact with the airflow set in motion by the fan and generate noise include the support arms and the volute nozzle.

[0010] Furthermore, changes in the turbulence regime of the fluid flow are observed within the air streams, particularly in the boundary layers of air near the lower and upper surfaces of the propeller blades. Such changes in the turbulence regime exacerbate noise pollution.

[0011] The perceived level of noise is primarily related to the amplitude of the acoustic noise generated by the blades. This amplitude depends mainly on the type of fluid flow observed and the natural frequencies of vibration.

[0012] There is a commercial interest in reducing the nuisances perceived by the user, for hair dryers and for many other household appliances.

[0013] Other hair dryer propellers with optimized mechanical structures have been proposed to reduce the noise generated. However, existing propellers either have insufficient airflow (increasing the hair dryer's energy consumption), unsatisfactory noise reduction performance, or a complex mechanical structure that makes them difficult to manufacture.

[0014] For example, US patent 2009 / 0185906 discloses a propeller designed to reduce noise. In other fields, propellers designed to reduce noise are also known, such as in building ventilation (see JP2002213391A) or in electronic component cooling (see US patent 2007 / 116561).

[0015] These different centrifugal propellers all have a plurality of radial air passage channels but still have room for improvement. DESCRIPTION GENERALE DE L'INVENTION

[0016] In view of the above, there is a need for a rotating blower part that generates a high flow radial airflow by setting in motion an incoming airflow, while causing little noise during operation.

[0017] Specifically, the amplitude of the acoustic noise generated by the turbulence of the rotating part must be minimized. With the same goal of reducing noise, the blade passage frequency of the rotating part should be as high as possible. Indeed, a high blade passage frequency minimizes the energy of the noise emitted by the rotating part. The noise level perceived by the user is therefore minimized.

[0018] The part sought must in particular be suitable for use in a domestic appliance dedicated to hairdressing, such as a hair dryer, and be limited to noise levels acceptable for these applications.

[0019] There is an additional need for a rotating part capable of generating a high-volume radial airflow, while requiring a moderate amount of material for its manufacture. Preferably, the desired rotating part should have a small footprint and low mass. The device incorporating the part must also remain compact.

[0020] We are also looking for a part that is not complex to manufacture.

[0021] The present invention relates to a propeller according to claim 1, preferred embodiments according to claims 2 to 13 and a blowing apparatus according to claim 14.

[0022] According to a first aspect of the invention, a propeller for a blowing device is proposed for this purpose, the propeller being configured to be driven in rotation around a longitudinal axis, the propeller comprising a proximal wall defining an inlet opening provided to admit into the propeller a flow of air directed along the longitudinal axis,

[0023] the propeller further comprising a plurality of air passage channels in fluidic communication with the inlet opening, said air passage channels being positioned around the longitudinal axis, each air passage channel extending radially outwards from the longitudinal axis, between an inlet end and an outlet end, in which the outlet end has an outlet section having a maximum dimension parallel to the longitudinal axis greater than or equal to 4 millimeters, the respective outlet sections of the air passage channels are arranged in a staggered pattern, so that said outlet sections together form a honeycomb structure, at least one air passage channel is delimited by a plurality of channel walls extending between the inlet end of said channel and the outlet end of said channel,and at least one of said channel walls having a thickness at the inlet end greater than the thickness of said channel wall at the outlet end.

[0024] In a rotating propeller according to the invention, in response to the propeller's rotation, an airflow is admitted at the inlet opening and then radially expelled outwards. The radial airflow passes through the inlet and outlet ends of the air passage channels. A high flow rate of radial output can be achieved.

[0025] The volume exiting each radial air passage channel is less than the volume set in motion between two blades of a standard hairdryer fan. This limits the noise caused by the collision of the small volume of air exiting each channel with fixed parts of the hairdryer.

[0026] Furthermore, an increase in blade passage frequency is observed compared to a prior art centrifugal propeller. The acoustic noise generated by the air movement within the propeller is therefore higher-pitched. The "blade passage frequency" is a concept well known to those skilled in the art and corresponds to the product of the number of propeller blades and the propeller's rotational speed.

[0027] The number of air discharge points is also increased due to the multiplication of radial air passage channels. The airflow generated in each radial air passage channel thus approaches laminar flow, and turbulent acoustic noise is limited. At a constant outlet airflow rate, the total energy of the generated acoustic noise is reduced compared to a prior art centrifugal propeller.

[0028] The propeller of the invention is similar to a centrifugal propeller which would have a high number of equivalent blades.

[0029] The proposed shape of the outlet sections of the air passage channels, and in particular the maximum dimension parallel to the longitudinal axis greater than or equal to 4 mm, makes it possible to significantly reduce noise pollution, while ensuring a sufficient flow rate of the outgoing radial flow for the main applications envisaged (in particular for incorporating the propeller into a hair dryer).

[0030] Furthermore, the proposed shape for the outlet ends of the air passage channels, and in particular the maximum dimension parallel to the longitudinal axis greater than or equal to 4 mm, limits the total amount of material required for the channel walls, which reduces the total mass of the propeller and optimizes its efficiency.

[0031] Optional and non-limiting characteristics of a propeller as defined above are as follows, taken alone or in any of the possible combinations: For at least one air passage channel, the maximum dimension of the outlet cross-section parallel to the longitudinal axis is between 4 and 10 millimeters, preferably between 5 and 7 millimeters, and advantageously equal to 6 millimeters. The outlet cross-section has a minimum dimension parallel to the longitudinal axis strictly less than the maximum dimension, the minimum dimension preferably being less than 10 millimeters and more preferably between 1 and 4 millimeters. The outlet cross-sections of the air passage channels are hexagonal in shape. The helix is ​​a helico-centrifugal type.the inlet opening has an inlet edge, and an angle γ between the longitudinal axis and a plane tangent to the proximal wall at the level of said inlet edge is between 50 degrees and 85 degrees, more preferably between 60 degrees and 70 degrees, the inlet end of at least one air passage channel has an inlet section having a maximum dimension parallel to the longitudinal axis less than or equal to the maximum dimension of the outlet section of said air passage channel, said maximum dimension of the inlet section being preferably between 2 millimeters and 12 millimeters, more preferably between 2 millimeters and 6 millimeters.The inlet section of said air passage channel has a shape identical to the shape of the outlet section of said air passage channel, and in which successive sections of said air passage channel from the inlet section to the outlet section have respective dimensions parallel to the longitudinal axis, progressively increasing in size. At least one air passage channel comprises an outlet section having a first center and further comprises an inlet section having a second center, an outlet radial direction passing through the first center being angularly offset by an angle β in a radial plane passing through the longitudinal axis, in a direction away from the inlet opening, relative to an inlet radial direction orthogonal to the longitudinal axis and passing through the second center.The number of air passage channels is between 30 and 100, preferably between 50 and 80, and more preferably 66. The propeller comprises a plurality of stages of air passage channels along the longitudinal axis, the number of stages being greater than 3, preferably greater than 5, and more preferably 6. The inlet opening has a circular cross-section with an inner diameter between 10 mm and 60 mm, preferably between 30 mm and 40 mm, and more preferably 36.5 mm. The propeller has an outer diameter between 30 mm and 90 mm, preferably between 50 mm and 70 mm, and more preferably 60 mm.The helix has a length along the longitudinal axis of between 3 millimeters and 40 millimeters, said length preferably being between 10 millimeters and 40 millimeters and more preferably equal to 26.5 millimeters. The helix further comprises a distal wall opposite the proximal wall, the air passage channels being interposed between the proximal and distal walls, and, preferably, a plurality of longitudinal separating walls connecting the proximal and distal walls, each of said longitudinal separating walls being contained in a respective radial plane passing through the longitudinal axis. The inlet ends together form a domed frustoconical surface extending around the longitudinal axis, the inlet opening forming a large base of the domed frustoconical surface.

[0032] According to a second aspect, the invention relates to a domestic blowing device dedicated to hairdressing, preferably a hair dryer, the device comprising a propeller as defined above.

[0033] A blowing apparatus according to the second aspect of the invention may have the following optional and non-limiting feature: the blowing apparatus includes an air straightening device, the air straightening device being designed to straighten a radial airflow emerging from the outlet ends of the propeller so as to form an axial airflow parallel to the longitudinal axis.

[0034] In particular, in the case mentioned above where the propeller has a distal wall opposite to the proximal wall of the propeller with respect to the longitudinal axis, the aforementioned air straightening device may include an external wall in line with the proximal wall, and / or an internal wall in line with the distal wall. DESCRIPTION GENERALE DES FIGURES

[0035] Other features, purposes and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings, among which: [ Fig. 1 ] There Figure 1 is a perspective view from above of a propeller for a blowing apparatus according to an embodiment of the invention. Fig. 2 ] There Figure 2 represents the helix of the Figure 1 view from the inside, in cross-section along a radial plane passing through the longitudinal axis A. Fig. 3 ] There Figure 3 schematically illustrates an inlet section of one end of a radial air passage channel formed by the propeller of the Figure 1 . [ Fig. 4 ] There Figure 4 schematically illustrates an outlet section of one end of a radial air passage channel formed by the propeller of the Figure 1 . [ Fig. 5 ] There Figure 5 schematically represents three juxtaposed air passage channels. Fig. 6 ] There Figure 6 schematically represents the helix of the Figure 1 cross-sectional view along a transverse plane orthogonal to the longitudinal axis A. Fig. 7a ] There Figure 7a illustrates the internal components of a hair dryer according to an example embodiment, including a propeller conforming to the example of the Figure 1 . [ Fig. 7b ] There Figure 7b is a view of the same hair dryer, in which some of the external components of the hair dryer are visible. Fig. 8 ] There Figure 8 is a longitudinal cross-sectional view of a hair dryer equipped with a propeller conforming to the Figure 1 . DESCRIPTION DETAILLEE DE MODES DE REALISATION DE L'INVENTION

[0036] We will describe in what follows a rotating part based on a specific embodiment, incorporated into a hairdryer, in which the rotating part is a propeller. It will be understood, however, that the propeller described below can be used, with the same advantages, in other types of blowing devices.

[0037] Any blowing device which requires generating a radial airflow outwards from an incident airflow may advantageously include a propeller described below.

[0038] Throughout this document, "axial flow" refers to a flow along a direction generally parallel to an axis of rotation of the rotating part, and "radial flow" refers to a flow along a direction that is generally perpendicular to an axis of rotation of the rotating part and that intersects the axis of rotation. The terms "upstream" and "downstream" refer to the direction of airflow.

[0039] Throughout the attached figures and the description below, similar elements bear identical alphanumeric references. Hélice hélico-centrifuge

[0040] We represented in Figure 1 A propeller 10 according to an embodiment of the invention. The propeller 10 is intended to be incorporated into a hair dryer 1, in a longitudinal portion of the hair dryer, generally called the barrel, which preferably extends perpendicularly to the direction of extension of a handle of the hair dryer. The propeller 10 is positioned downstream of an air inlet zone 2 of the hair dryer, and upstream of an air outlet zone 6 of the hair dryer. The propeller 10 is designed to be driven in rotation by a motor, preferably an electric one. During the operation of the hair dryer, the forced rotation of the propeller 10 causes the air to move inside the propeller 10, and consequently inside and near the hair dryer 1, as illustrated in the figures.

[0041] The propeller 10 is driven in rotation around an axis A. The axis A is an axis of rotation of the propeller 10. The axis A serves preferably and also as an axis of revolution symmetry for the propeller 10.

[0042] The helix 10 is preferably manufactured by injection molding. A major material of the helix 10 is preferably a polymer material, such as polypropylene (PP) or polyamide reinforced with glass fibers or glass beads (PAGF).

[0043] The helix 10 preferably comprises a proximal wall 4 and a distal wall 5. The "proximal" wall is arranged to be located on the side closest to an air inlet zone 2 of the hair dryer, and the "distal" wall is located on the far side of the air inlet zone 2. The distal wall 5 is axially opposed to the proximal wall 4.

[0044] The proximal wall 4 and the distal wall 5 are preferably circular, as can be seen on the Figure 1 These two walls preferably extend in substantially parallel planes. The helix 10 thus has a cylindrical external shape. A plurality of air passage channels 3, a detailed description of which is provided below, are interposed between the proximal wall 4 and the distal wall 5 in an axial direction (along axis A).

[0045] In the orientation of helix 10 illustrated on the Figure 1 , the proximal wall 4 is directed upwards and the distal wall 5 is directed downwards.

[0046] The proximal wall 4 has a concentric outer edge 400 and inner edge 401. The outer edge 400 is preferably circular. The inner edge 401 is also preferably circular, and this inner edge 401 defines an inlet opening 40 designed to admit an incoming airflow into the propeller 10. The inner edge 401 therefore also constitutes an inlet edge 401. The incoming airflow is typically axial, directed parallel to the axis A. The inlet opening 40 is therefore located around, and contains, the axis A.

[0047] The inner edge 401 is preferably contained in a plane perpendicular to the longitudinal axis A. Thus, the inlet opening 40 extends transversely to the axis A, and preferably perpendicularly to the axis A.

[0048] An intake opening diameter ID (40) is preferably between 10 and 60 millimeters, and more preferably between 30 and 40 millimeters. Here, the ID diameter is 36.5 millimeters. Such dimensional ranges were chosen by the inventors because they offer the best possible compromise between propeller performance (in particular the airflow it can generate) and propeller size.

[0049] The inlet opening 40 defines one side of a central cavity in the propeller 10. The propeller 10 is thus hollow. The central cavity of the propeller 10 is further defined by the inlet ends 320 of the air passage channels 3. According to the invention, the propeller is a centrifugal propeller, and in this example, the propeller 10 is a helico-centrifugal type propeller. The propeller operates as follows: air is drawn in through the inlet opening 40, enters the air passage channels 3 through their inlet ends 320, and is then expelled centrifugally, i.e., radially, through outlet ends 321, as will be detailed later. In addition to this centrifugal motion of the air, a helical motion is also imparted to the air, as explained below. In other words, the air undergoes two movements: a centrifugal (radial) movement combined with a helical (axial) movement.

[0050] As can be seen on the Figures 1 And 2 A plane P tangent to the inlet opening 40 at the level of the internal edge 401 and including the proximal wall 4 defines with the axis A an angle γ not equal to 90 degrees. The angle γ, which is illustrated on the Figure 2 The angle of inclination is preferably between 50 and 85 degrees, and more preferably between 60 and 70 degrees. Thus, the proximal wall 4 does not lie in a single plane perpendicular to axis A. In other words, the proximal wall 4 is inclined and not perpendicular to the axis A of rotation of the propeller. Such a design allows the airflow to be given a helico-centrifugal motion, taking into account the rotation of the propeller.

[0051] One advantage of the inclined proximal wall 4 is that using a helico-centrifugal type propeller allows for good pressure resistance of the propeller 10 during its rotation, while simultaneously moving air within the air passage channels 3 at a significant flow rate. Thus, by selecting the above value ranges for the angle γ, the inventors found the best possible compromise between the propeller's pressure resistance and the flow rate. "Pressure resistance" refers to the propeller's ability to continue functioning properly, i.e., to continue moving air, even if the pressure increases. This is particularly relevant when the air outlet is partially obstructed, for example, when a concentrator nozzle accessory 11 is attached to the end of the hairdryer, as can be seen, for instance, in the Figure 7a Or 7b .

[0052] Alternatively, the propeller can be a strictly centrifugal type. The plane P, comprising the proximal wall 4 and tangent to the inlet opening, then defines an angle with axis A between 85 and 95 degrees, and preferably an angle of 90 degrees. Such a propeller prioritizes pressure resistance, possibly at the expense of flow rate, thus compensating for numerous pressure losses.

[0053] Optionally, as can be seen in the Figure 1 A plurality of separating walls 51 are provided in the body of the helix 10. Each separating wall 51 connects the proximal wall 4 and the distal wall 5. Each separating wall 51 extends between the central cavity of the helix 10 and an outer periphery of the helix 10.

[0054] By "outer periphery" is meant the surface formed by all the outlet ends 321 of the air passage channels 3, this outer periphery having a generally cylindrical shape in the present example. Preferably, each separating wall 51 lies in a radial plane passing through the longitudinal axis A of the helix 10. The separating walls 51 thus form radii of the helix 10. In the orientation of the Figure 1 The separating walls 51 have a vertical arrangement.

[0055] One advantage of incorporating the separating walls 51 is that it greatly facilitates the industrialization of the propeller, and in particular the demolding of the propeller 10 during its manufacture. For example, the construction of the propeller 10 of the Figure 1 requires only eleven demolding drawers. It is estimated that twenty-two demolding drawers would be required in the absence of the separating walls 51.

[0056] Advantageously, the outer diameter ED of the propeller 10 is between 30 millimeters and 90 millimeters. Thus, the propeller 10 remains compact and can be easily integrated into a hair dryer.

[0057] More preferably, the outer diameter ED is between 50 millimeters and 70 millimeters, and here it is equal to 60 millimeters, so as to correspond to the usual diameter of the barrel of hair dryers.

[0058] Advantageously, the length L of the helix 10 along axis A is between 3 millimeters and 40 millimeters. Thus, the helix 10 occupies a small volume between the air inlet and outlet of the hair dryer, and can be easily integrated into the hair dryer.

[0059] The length L is preferably between 10 millimeters and 40 millimeters, and this length L is here equal to 26.5 millimeters. This range was selected by the inventors to offer the best possible compromise between propeller size and aerodynamic performance: indeed, it will be understood that the greater the number of air passage channels 3, the better the performance, but the propeller is bulkier. Canaux radiaux de passage d'air

[0060] The centrifugal propeller 10, whether strictly centrifugal or helico-centrifugal, is used to generate an outgoing radial airflow outward from the axis A, from an incoming airflow at the inlet opening 40. The outgoing radial airflow is generated when the propeller 10 is driven in rotation around the axis A, for example by means of an electric motor.

[0061] For the generation of the outgoing radial airflow, the propeller 10 comprises a plurality of air passage channels 3.

[0062] The air passage channels 3 are distributed around the axis A. Each air passage channel 3 advantageously extends in a general radial direction with respect to the axis A, outwards from the axis A. Each air passage channel 3 has an inlet end 320, an outlet end 321 and channel walls 36 extending between the inlet end 320 and the outlet end 321. The inlet end 320 is closer to the axis A than the outlet end 321.

[0063] Thus, an airflow admitted into a given air passage 3, via the inlet end 320, is driven in a generally radial direction and away from the axis A by the centrifugal force generated by the rotation of the propeller. This airflow is directed by the channel walls 36 of the same air passage 3 and emerges at the outlet end 321 of the same air passage 3. Each air passage 3 is in fluidic communication with the inlet opening 40 of the propeller 10, allowing an airflow entering the inlet opening 40 to flow through the air passage 3.

[0064] The overall structure of the helix 10 can be described as a "multicellular" structure. The air passage channels 3 form juxtaposed cells that direct air outwards from the helix 10 under the effect of centrifugal force during the helix's rotation. The volume of air directed outwards from each "cell," that is, from each air passage channel 3, is small. This limits the noise generated by the collision between this volume of outgoing air and fixed components of the hairdryer (not included in the helix 10), such as, for example, the blades of a straightener. However, the number of these channels ensures sufficient airflow. In this example, the air passage channels 3 are axially interposed between the proximal wall 4 and the distal wall 5 of the helix 10.As stated above, the inlet ends 320 of the air passage channels define with the proximal wall 4 a central cavity of the helix 10. Said central cavity is concentric with the cylindrical outer periphery of the helix 10.

[0065] We have represented on the Figure 2 helix 10 seen from the inside, in section along a radial plane passing through the longitudinal axis A.

[0066] The distal wall 5 closes the side of the helix 10 that is opposite the inlet opening 40. Said opposite side is located at the bottom of the Figure 1 and at the bottom of the Figure 2 .

[0067] A mounting hub 54 is formed in the helix 10, at the center of the distal wall 5. The mounting hub 54 provides a central channel 52 extending along the axis A. A motor drive shaft can be inserted at the central channel 52 and then secured to the mounting hub 54 in order to rotate the helix 10.

[0068] The length of the mounting hub 54 must be sufficient to securely mount the propeller 10 onto a rotating shaft driven by a hairdryer motor. The length of the mounting hub 54 is preferably greater than 6 millimeters.

[0069] In this example, the inlet ends 320 together form a domed frustoconical surface 42. Successive cross-sections (perpendicular to axis A) of the domed frustoconical surface 42, in a direction away from the inlet opening 40, have a progressively smaller area until they reach a minimum cross-section 41. Thus, the inlet opening 40 forms a "large base" of the domed frustoconical surface 42. The minimum cross-section 41 is located at a "small base" of the domed frustoconical surface 42. As can be seen on the figure 2 , the small base is oriented towards the mounting hub 54, or towards the distal wall 5, while the large base is oriented towards the proximal wall 4.

[0070] The edges of the domed frustoconical surface 42 (visible in radial planes including axis A, for example in the cutting plane of the Figure 2 The edges are preferably not straight, but curved. The frustoconical surface is thus convex, and advantageously has a general bowl shape. The convex frustoconical surface is concave.

[0071] One advantage of the curved shape of the edges of the domed frustoconical surface 42 (general bowl shape) is that it increases the total airflow inlet area, particularly compared to a cylindrical inlet surface 320. Therefore, the domed frustoconical surface 42 is advantageous for reducing overall size while maintaining good aerodynamic performance.

[0072] However, the surface formed by the inlet ends 320 of the air passage channels 3 can alternatively have a general shape of a straight cylinder, or of a truncated cone or a right cone.

[0073] The number of air passage channels 3 is advantageously between 60 and 120, and is preferably between 60 and 80. The number of air passage channels 3 is here equal to 66.

[0074] The number of air passage channels 3 of the propeller 10 is chosen to be high. This increases the number of air discharge points, which reduces the energy of the acoustic noise generated when the propeller 10 is rotated. It also increases the volume of air set in motion and therefore the flow rate generated by the propeller. However, the total number of air passage channels 3 must not be excessive, in order to limit the amount of material required for the channel walls 36 and to reduce manufacturing complexity. This also allows, for a given outside diameter ED, for channel cross-sections to be maintained with sufficient dimensions, as will be detailed later. This ensures a good material volume / air passage volume ratio. It is also observed that, thanks to the increased number of air passage channels 3, the peaks of the acoustic noise due to the rotation of the propeller 10 are of low amplitude.

[0075] The air passage channels 3 are preferably stacked in at least two tiers along axis A. Thus, the airflow entering the inlet opening 40 encounters several successive tiers of channels. The number of tiered channels is preferably greater than 3, and even more advantageously greater than 5. The propeller 10 therefore has a large number of air passage channels 3 and thus numerous air discharge points. The total energy of the acoustic noise generated by the rotation of the propeller 10 is reduced, while maintaining a substantial flow rate, as explained previously.

[0076] Furthermore, the number of channel levels is preferably less than 10, to limit the overall size of the room as well as the amount of material needed to manufacture the channel walls 36.

[0077] In this example, the number of channel stages is 6.

[0078] These numbers of channel stages were chosen by the inventors for their remarkable compromise between aerodynamic performance (flow rate, noise, etc.) and propeller size, particularly along the A axis.

[0079] The number of air passage channels per floor is preferably between 10 and 15 channels per floor. In this example of the Figure 1 There are eleven air passage channels 3 for each channel level. It should be noted that a hexagonal channel divided in the middle by a separating wall 51 is counted as a single air passage channel 3. It is advantageous for the number of air passage channels 3 per level to be a prime number (here 11), in order to limit harmonics. Noise due to the rotation of the room is thus further reduced.

[0080] Advantageously, each air passage channel 3 has, at its outlet end 321, an outlet section 34, illustrated in the Figure 3 , of which a maximum dimension b (oriented parallel to the axis of rotation A of the helix 10) is between 4 millimeters and 10 millimeters. The outlet section 34 and the inlet section 33 are taken respectively perpendicular to a plane containing the outlet end 321 and to a plane containing the inlet end 320.

[0081] The maximum dimension b of the outlet section 34 influences the volume of air exiting the air passage channel 3 when the propeller 10 is set in motion. The maximum dimension b is chosen here to be sufficiently small to reduce this exiting air volume. This reduces noise caused by the collision of this exiting air volume with adjacent fixed elements, such as the blades of a hairdryer straightener.

[0082] More advantageously, the maximum dimension b of the outlet section 34 is between 5 millimeters and 7 millimeters, which represents a remarkable compromise between noise reduction and a substantial flow rate. The inlet end 320 of each air passage channel 3 has an inlet section 33, illustrated in the Figure 3 , of which a maximum dimension a (oriented parallel to the axis of rotation A of the propeller 10, as is the maximum dimension b) is preferably less than or equal to the maximum dimension b of the outlet section 34.

[0083] In other words, the internal volume of the air passage channel 3 increases radially with respect to the axis of rotation A, between its inlet end 320 and its outlet end 321.

[0084] Advantageously, the maximum dimension a of the inlet section 33 of a given air passage channel 3 is between 70% and 95% of the maximum dimension of the outlet section 34 of the same air passage channel 3. More preferably, the maximum dimension a is between 75% and 85% of the maximum dimension b, and amounts for example to 80% of the maximum dimension b.

[0085] The maximum dimension a of the inlet section 33 is chosen to be small enough to allow a plurality of stages of air passage channels to be arranged along the axis of rotation A, as well as the mounting hub 54. The total length L of the propeller 10 (which is preferably between 10 millimeters and 40 millimeters) must be sufficient to accommodate said hub and several stages of channels, but not too large to allow easy integration of the propeller 10 into a hair dryer.

[0086] As an example, we have represented in Figure 3 the inlet section 33 of an air passage channel 3 of the propeller 10. The Figure 4 represents the outlet section 34 of the same air passage channel 3.

[0087] In this example, output section 34 presents (on the Figure 4 ) a hexagonal shape.

[0088] The maximum dimension b of the exit section 34 along the axis of rotation A corresponds here to the length of the median segment which connects the top vertex and the bottom vertex.

[0089] In the example of the Figure 4 , the maximum dimension b is equal to 6 millimeters.

[0090] A hexagonal shape for the outlet sections 34 of the propeller 10 is advantageous because the free area available for airflow is optimized. The flow rate of the outgoing radial airflow is maximized.

[0091] Another advantage of the hexagonal shape of the outlet sections 34 is the possibility of arranging the outlet sections 34 of the air passage channels 3 in a staggered pattern relative to each other. This reduces the overall size and mass of the propeller 10 as a whole.

[0092] The outlet sections 34 form a "honeycomb" structure. The honeycomb structure ensures good rigidity and mechanical resistance of the propeller 10. In addition, the space available for airflow is maximized while limiting the overall size of the propeller.

[0093] As can be seen in the figures, the hexagonal shape of the outlet sections 34 is particularly well suited to creating a honeycomb structure. As an alternative to the hexagonal shape, the outlet sections of the air passage channels could be square or rectangular.

[0094] Furthermore, the minimum dimension of the outlet section 34 along the axis of rotation A is here denoted w. This minimum dimension w is, preferably, strictly less than the maximum dimension a; the outlet section 34 thus preferably has a non-rectangular shape.

[0095] The minimum dimension w of the outlet section 34 corresponds, on the Figure 4 , to the length of the left and right sides of the perimeter of the outlet section 34. The minimum dimension w is preferably less than 10 millimeters, and is more preferably between 1 millimeter and 4 millimeters.

[0096] We also illustrated on the Figure 4 the width c of the outlet section 34 of the outlet end 321.

[0097] The width c, measured perpendicular to the axis of rotation A, is preferably between 4 millimeters and 20 millimeters. In this example, the width c is equal to more than 150% of the maximum dimension b.

[0098] The inlet section 33 preferably has the same general shape as the outlet section 34, that is to say here a hexagonal shape (visible on the Figure 3 ).

[0099] The maximum dimension a of the inlet section 33 along the axis of rotation A, which also corresponds to the length of the segment connecting the upper and lower vertices, is preferably between 2 millimeters and 12 millimeters. The maximum dimension a is more preferably between 2 millimeters and 6 millimeters.

[0100] As previously stated, the maximum dimension a of the inlet section 33 is, preferably, less than or equal to the maximum dimension b of the outlet section 34. The minimum dimension w of the inlet section 33 along the axis of rotation A is, in this example, equal to the minimum dimension w of the outlet section 34, i.e. preferably between 1 millimeter and 4 millimeters.

[0101] There Figure 5 illustrates three juxtaposed air passage channels 3 of the propeller 10. These three channels are shown isolated from the rest of the propeller 10 structure and viewed from above. The outlet ends 321 and the inlet ends 320 of each of these channels have shapes conforming to the diagrams of the Figure 3 and of the Figure 4 respectively.

[0102] As seen on the Figure 5 The channel walls 36 of the air passage channels 3 are bonded together. The channels are arranged in a staggered pattern. Two adjacent air passage channels 3 preferably share a common channel wall 36.

[0103] As an example, the right-hand wall of channel 36 for the channel located to the left of the Figure 5 is identical to the left canal wall for the canal to the right of the Figure 5 .

[0104] Advantageously, for each air passage channel 3, the successive sections of said channel, from the inlet end 320 to the outlet end 321, have respective dimensions parallel to the axis of rotation A which gradually increase in size.

[0105] We illustrated on the Figure 5 two hexagonal intermediate sections of the same air passage channel, at different radial positions from axis A, between the inlet end 320 and the outlet end 321 of said air passage channel. The first intermediate section is closer to the inlet end 320 than the second intermediate section.

[0106] The maximum dimension b1 of the first intermediate section, taken parallel to the axis of rotation A of the propeller 10, is advantageously strictly less than the maximum dimension b2 of the second intermediate section taken parallel to the axis of rotation A. This latter maximum dimension b2 is, itself, strictly less than the maximum dimension b of the outlet section 34 at the outlet end 321.

[0107] Preferably, the respective dimensions of successive sections of the same air passage channel 3 perpendicular to the axis of rotation A, from the inlet end 320 to the outlet end 321, also gradually increase in size.

[0108] At the outlet end 321, the channel walls 36 for a given air passage channel (six walls here) preferably have the same thickness in the plane of the outlet section 34. Said thickness is preferably between 0.5 millimeter and 1 millimeter, and is here equal to 0.75 millimeter.

[0109] In the case where a vertical separating wall 51 passes through the middle of the outlet end 321 (which is not the case on the Figure 5 ), the separating wall 51 preferably also has a thickness between 0.5 millimeter and 1 millimeter, for example equal to 0.75 millimeter.

[0110] According to the invention, at least one of the channel walls 36 of a given air passage channel 3 has a greater thickness at the inlet end 320 of said channel than at the outlet end 321 of said channel. Preferably, all six channel walls 36 of said channel have such a difference in thickness between the inlet end 320 and the outlet end 321.

[0111] For example, a channel wall thickness 36 at the inlet end 320 is equal to 1.3 millimeters.

[0112] One advantage of the difference in thickness between the inlet and outlet of the air passage channels 3 is to facilitate demolding during the manufacture of the propeller 10. A draft is formed at the channel walls 36; the channel walls 36 are thinner on the outside than on the inside.

[0113] There Figure 6 illustrates a cross-sectional view of propeller 10. The cross-sectional plane is a transverse plane orthogonal to the axis of rotation A of propeller 10. The cross-sectional plane thus passes through a single channel stage; the eleven air passage channels 3 included in said channel stage are visible on the Figure 6 .

[0114] As seen on the Figure 6 , the channel walls 36 of helix 10 are advantageously not included in radial planes.

[0115] As an air passage channel 3 of the upper half of the propeller (depending on the orientation of the Figure 6 ) extends radially outwards, the walls of channel 36 delimiting said channel shift to the right.

[0116] We have represented on the Figure 6 a center 340 of the outlet section 34 and a center 330 of the inlet section 33 of the same air passage channel 3. It is recalled here that the inlet section 33 and the outlet section 34 are hexagonal.

[0117] We have represented on the Figure 6 A transverse output direction F1 is shown; the direction F1 is orthogonal to the axis of rotation A, passes through the axis of rotation A and passes through the center 340 of the output section 34. A transverse input direction F2 is also shown; the direction F2 is orthogonal to the axis of rotation A, passes through the axis of rotation A and passes through the center 330 of the input section 33.

[0118] The direction F1 is offset by an angle α, relative to the direction F2. The angle α is for example between 1 degree and 10 degrees.

[0119] One advantage of such an offset of the channel walls 36 is to accelerate the radial airflow as said flow progresses outwards. The flow rate of the outgoing flow is then increased.

[0120] Back to the cross-sectional view of the Figure 2 along a radial plane, as a given air passage channel 3 extends outwards, the channel walls 36 delimiting said channel also shift downwards.

[0121] We have represented on the Figure 2 a radial output direction F'1; the direction F'1 passes through the axis of rotation A and passes through the center 340 of the output section 34. A radial input direction F'2 has also been shown; the direction F'2 is orthogonal to the axis of rotation A, intersects the direction F'1 at a point located on the axis of rotation A, and passes through the center 330 of the input section 33.

[0122] Direction F'1 is offset downwards by an angle β relative to direction F'2. For example, angle β is between 5 and 20 degrees. This creates a gradual transition between the generally axial direction of the airflow entering through the intake opening 40 and the desired generally radial direction of the exiting airflow. This improves the performance of propeller 10. Exemple de sèche-cheveux

[0123] The propeller 10 is incorporated into an air circulation chamber of a hair dryer. Throughout this text, a hair dryer 1 comprising the propeller 10 is described.

[0124] The hair dryer 1 includes a handle allowing the user to hold the hair dryer 1. This handle is not shown in the Figures 7a , 7b And 8 The handle typically includes buttons for manually controlling the hair dryer.

[0125] The hair dryer also includes a longitudinal portion, also called a barrel, extending parallel to the axis of rotation A of the propeller 10.

[0126] An air inlet zone 2 of the hair dryer 1 is located at one end of the longitudinal portion and an air outlet zone 6 of the hair dryer 1 is located at the other end. An air circulation chamber extends between the inlet zone and the outlet zone.

[0127] During operation of the hair dryer 1, ambient air is drawn in at the air inlet zone 2. The ambient air enters the air circulation chamber through an inlet opening 20 in the air inlet zone 2, and is then moved along the air circulation chamber to the air outlet zone 6. The outlet zone 6 typically has a circular shape. As can be seen on the Figures 7a And 7bIt is also possible, in a manner known as such, to removably mount an accessory 11 onto the air outlet 4 to modify the shape of the airflow emitted by the hairdryer. In the illustrated example, accessory 11 is a concentrator nozzle used to focus the airflow to a specific point. As is known, this type of accessory is typically used for styling hair.

[0128] The inlet opening 20 is, for example, circular, and includes, for example, a grille through which the incoming airflow is admitted. The inlet opening 20 preferably has the axis of rotation A of the propeller 10 as its axis of rotational symmetry.

[0129] The propeller 10 is positioned downstream of the air inlet zone 2 of the hair dryer 1 and upstream of the air outlet zone 3, in the air circulation chamber. The propeller 10, through its rotation, is responsible for setting the air in motion within the air circulation chamber.

[0130] A general architecture of hair dryer 1, for example, conforms to the hair dryer in publication WO 2017 / 017330 A1, in relation to the Figure 1 of this document.

[0131] The hair dryer 1 includes an electric motor 8 carrying a rotating shaft. The electric motor 8 is visible on the Figure 7a , which illustrates some internal components of the hair dryer. The rotating shaft is mechanically connected to the propeller 10, so that the propeller 10 can be driven in rotation around the axis A. In this example, the rotating shaft extends along the axis A, and the propeller 10 is directly mounted on the rotating shaft via the mounting hub 54 described previously.

[0132] A shock absorber, also called a "silent block" according to common terminology, can be provided on the periphery of the electric motor 8 to dampen the vibrations of said motor.

[0133] The rotational speed of the electric motor 8 is sufficient to ensure a high flow rate of the air exiting the propeller 10. Preferably, the rotational speed of the electric motor is between 5,000 revolutions per minute and 30,000 revolutions per minute. The propeller 10 is preferably driven to rotate counterclockwise.

[0134] For example, if the electric motor rotates at 15,000 revolutions per minute, the flow rate of the air exiting the propeller 10 can be between 40 cubic meters per hour and 90 cubic meters per hour.

[0135] There Figure 7b illustrates the hair dryer 1 in the same orientation as the Figure 7a Additional components of the hair dryer 1, located on top of certain internal components visible on the Figure 7a are visible on the Figure 7b .

[0136] In particular, the hair dryer advantageously includes a straightener 7 located downstream of the helix 10. The straightener 7 has an outside diameter greater than the outside diameter ED of the helix 10. The straightener 7 is preferably positioned in the vicinity of the distal wall 5 of the helix 10.

[0137] One function of the straightener 7 is to channel the airflow exiting the propeller 10 and to straighten said flow. In this example, the straightener 7 has, on its periphery, several straightener blades 70 advantageously having a helical shape. Thus, the straightener will transform the radial or helico-radial flow generated by the propeller 10 into an axial airflow that will be emitted from the air outlet zone 6.

[0138] The rectifier 7 visible on the Figure 7b including the 70 rectifier blades is replaceable by a rectifier having a spiral shape (in "snail's spiral").

[0139] We have represented on the Figure 8 a longitudinal cross-sectional view of hair dryer 1, illustrating elements of the inside of the hair dryer.

[0140] An outer casing 6 of the hair dryer 1, extending around the motor block 8 and the rectifier 7, is visible on the Figure 8 .

[0141] The outer shell 6 notably has an inner shell wall 60. The inner shell wall 60 faces the straightener, in the air circulation chamber.

[0142] The straightener 7 forms with the inner shell wall 60 an air straightening device, designed to straighten the radial airflow emerging from the outlet ends 321 of the propeller 10 so as to form an axial airflow. In a preferred configuration, the inner shell wall 60 extends from the vicinity of the outer edge 40 of the proximal wall 4 of the propeller 10. Furthermore, the straightener 7 preferably extends from the outer edge 50 of the distal wall 5 of the propeller 10.

[0143] One advantage of this preferred configuration is that the radial airflow exiting the propeller 10 is guided by the inner hull wall 60 and by the straightener 7, to form an axial airflow directed along the axis of rotation A towards the air outlet area 3.

[0144] As can be seen on the Figure 8 During the operation of the hair dryer 1, the axial airflow exiting through the air outlet area 3 emerges mainly parallel to the axis of rotation A. It will be understood that, the higher the flow rate of the radial airflow exiting the propeller 10, the higher the flow rate of the axial airflow emerging from the hair dryer 1.

[0145] The propeller 10, featuring a plurality of air passage channels 3 in a "multi-cell" configuration, thus provides an efficient solution for obtaining a high flow rate radial outgoing airflow, while greatly reducing the noise generated by the rotation of the propeller.

[0146] Due to the presence of a large number of air passage channels, propeller 10 has a high number of equivalent blades.

[0147] The amplitude of the acoustic noise is reduced. In addition, the blade passage frequency of propeller 10 is higher than the blade passage frequency of a standard centrifugal propeller, which makes the acoustic noise higher-pitched and less harmful to the human user.

[0148] Note that an alternative rotating part for a hairdryer can be formed by gluing two identical propellers back-to-back, for example conforming to the structure illustrated on the Figures 1 à 6 The term "back-to-back" means that the faces containing the mounting hubs can be arranged against each other, so as to obtain a rotating part with twice the length. One advantage of such a rotating part is to increase the flow rate of the outgoing radial airflow, for an unchanged rotational speed of the rotating part (preferably between 5,000 rpm and 30,000 rpm).

Claims

1. Propeller (10) for domestic blowing device dedicated to hairstyling, the propeller being configured to be driven in rotation around a longitudinal axis (A), the propeller comprising a proximal wall (4) defining an intake opening (40) intended to admit into the propeller an air flow directed along the longitudinal axis (A), the propeller further comprising a plurality of air passage channels (3) in fluid communication with the intake opening (40), said air passage channels (3) being positioned around the longitudinal axis (A), each air passage channel (3) extending radially outward from the longitudinal axis (A), between an inlet end (320) and an outlet end (321), the respective outlet sections (34) of the air passage channels (3) being arranged in staggered manner such that said outlet sections (34) collectively form a honeycomb structure, and at least one air passage channel (3) being delimited by a plurality of channel walls (36) extending between the inlet end (320) of said channel and the outlet end (321) of said channel, characterized in that the outlet end (321) has an outlet section (34) having a maximum dimension (b) parallel to the longitudinal axis (A) that is greater than or equal to 4 millimeters, and in that at least one of said channel walls (36) has a thickness at the inlet end (320) greater than a thickness of said channel wall (36) at the outlet end.

2. Propeller according to claim 1, wherein, for at least one air passage channel (3), the maximum dimension (b) of the outlet section (34) parallel to the longitudinal axis (A) is between 4 millimeters and 10 millimeters, preferably between 5 millimeters and 7 millimeters, and advantageously equal to 6 millimeters.

3. Propeller according to one of claims 1 or 2, the outlet section (34) having a minimum dimension (w) parallel to the longitudinal axis (A) strictly less than the maximum dimension (b), the minimum dimension (w) preferably being less than 10 millimeters and more preferably between 1 millimeter and 4 millimeters.

4. Propeller according to any one of claims 1 to 3, wherein the outlet sections (34) of the air passage channels (3) have a hexagonal shape.

5. Propeller according to any one of claims 1 to 4, the propeller (10) being of the helico-centrifugal type.

6. Propeller according to claim 5, wherein the intake opening (40) has an intake edge (401) and wherein an angle γ between the longitudinal axis (A) and a plane tangent to the proximal wall (4) at the intake edge (401) is between 50 degrees and 85 degrees, more preferably between 60 degrees and 70 degrees.

7. Propeller according to any one of claims 1 to 6, wherein the inlet end (320) of at least one air passage channel (3) has an inlet section (33) having a maximum dimension (a) parallel to the longitudinal axis (A) less than or equal to the maximum dimension (b) of the outlet section (34) of said air passage channel (3), said maximum dimension (a) of the inlet section (33) preferably being between 2 millimeters and 12 millimeters, more preferably between 2 millimeters and 6 millimeters.

8. Propeller according to any one of claims 1 to 7, wherein the number of air passage channels (3) is between 30 and 100, said number of channels preferably being between 50 and 80 and more preferably equal to 66.

9. Propeller according to any one of claims 1 to 8, wherein the intake opening (40) has a circular section with an inner diameter (ID) between 10 millimeters and 60 millimeters, said inner diameter (ID) preferably being between 30 millimeters and 40 millimeters and more preferably equal to 36.5 millimeters.

10. Propeller according to any one of claims 1 to 9, the propeller (10) having an outer diameter (ED) between 30 millimeters and 90 millimeters, said outer diameter (ED) preferably being between 50 millimeters and 70 millimeters and more preferably equal to 60 millimeters.

11. Propeller according to any one of claims 1 to 10, the propeller (10) having a length along the longitudinal axis (A) between 3 millimeters and 40 millimeters, said length preferably being between 10 millimeters and 40 millimeters and more preferably equal to 26.5 millimeters.

12. Propeller according to any one of claims 1 to 11, wherein the inlet ends (320) together form a convex truncated surface (42) extending around the longitudinal axis (A), the intake opening (40) forming a large base of the convex truncated surface (42).

13. Propeller according to any one of claims 1 to 12, the propeller (10) further comprising: ∘ a distal wall (5) opposite the proximal wall (4), the air passage channels (3) being interspersed between the proximal wall (4) and the distal wall (5), ∘ a plurality of longitudinal separating walls (51) connecting the proximal wall (4) and the distal wall (5), each of said longitudinal separating walls (51) being included in a respective radial plane passing through the longitudinal axis (A).

14. Domestic blowing device dedicated to hairstyling, preferably a hairdryer (1), comprising a propeller (10) according to any one of claims 1 to 13.

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