EP3367840B1 - Hairdryer with improved acoustic performance - Google Patents

Description

Subject of the invention

The present invention relates to a hair dryer with improved acoustic performance, and more particularly to a hair dryer with low noise level comprising at its air inlet a hollow tubular elbow equipped with one or more blades.

State of the art

Hairdryers on the market continue to be relatively noisy despite numerous efforts on the part of manufacturers to make them quieter. There is therefore a real demand from customers to reduce the noise level and make the spectrum of sound frequencies emitted more pleasant to the ear.

Many attempts have been made in this direction with mixed success because the means available to achieve this objective are limited, more particularly by budgetary constraints which do not allow the introduction of active noise reduction technologies, such as sounds in phase opposition, and because of the size and weight of the devices which must remain acceptable to the user.

One of the possible approaches to reduce the noise level of a hair dryer is the positioning at the air inlet of a silencer generally consisting of a hood fitted with open-cell foam or even pleated surfaces capable of absorbing the noise generated by the engine and the air flow. The documents FR 2 926 704 ; FR 2 983 043 ; WO 2010/045698 A1 as well as EP 2,412,272 A1 and EP 2 327 327 A1 belong to this category.

Another approach is that of reducing the air speed because the noise generated by an air flow in a hollow body is proportional to the power speed 8 (jet noise). To control this phenomenon, we imagined the use of several successive turbines. This type of provision is disclosed in WO 98/49500 .

The document US 2015/0237984 A1 discloses a high performance hairdryer with a reduced noise level comprising an insulating coating lining the inside of the housing. The air flow at the inlet of the turbine undergoes a particular deflection and the turbine comprises a ring with fins for rectifying a turbulent air flow.

The document DE 88 05 910 U1 discloses a hair dryer with a device designed to reduce noise. The air flow, before passing through the turbine, enters a box comprising baffles. The box comprising the baffles is aligned along the same axis as the body of the hair dryer comprising the turbine.

The document JP S53 164377 U describes a hair dryer comprising an anteroom located at the rear of a main body including a turbine. The passage of the flow from the anteroom to the main body of the device is done through baffles allowing to deflect the air flow before entering the turbine.

To our knowledge, there is currently no hair dryer on the market constituting a satisfactory compromise between weight, size and manufacturing cost, and acceptable acoustic performance.

Objects of the invention

The present invention aims to provide a quieter hair dryer than the devices of the prior art, with a sound spectrum from which the most troublesome frequencies have been eliminated, and constituting a good compromise between the weight, the bulk and the manufacturing cost.

Summary of the invention

• un corps tubulaire selon un axe longitudinal avec, à ses extrémités opposées, une entrée et une sortie d'air;
• une turbine située dans ledit corps tubulaire qui, en utilisation, est entraînée en rotation par un moteur selon la direction de l'axe longitudinal, ce qui permet d'aspirer l'air par l'entrée et d'expulser l'air par la sortie dudit corps tubulaire, caractérisé en ce que le sèche-cheveux comprend un coude d'entrée d'air comportant une ou plusieurs aubes globalement parallèles à la courbure du coude.

The present invention discloses a hair dryer comprising:

• a tubular body along a longitudinal axis with, at its opposite ends, an air inlet and outlet;
• a turbine located in said tubular body which, in use, is rotated by a motor in the direction of the longitudinal axis, which makes it possible to draw air in through the inlet and expel the air through the outlet of said tubular body, characterized in that the hair dryer comprises an air inlet bend comprising one or more blades generally parallel to the curvature of the bend.

• le coude d'entrée d'air comporte entre 3 et 6 aubes, de préférence 4 ou 5 aubes;
• le coude d'entrée d'air comporte en outre une ou plusieurs cloisons divisant les aubes;
• l'extrémité de sortie dudit coude d'entrée d'air, à l'entrée du cœur de l'enveloppe du sèche-cheveux, comprend une restriction de section, compensant la section occupée dans ledit coude par lesdites aubes;
• la distance entre les aubes est fixée de telle manière que le flux d'air à la sortie du coude d'entrée d'air et à l'entrée du cœur de l'enveloppe du sèche-cheveux possède substantiellement la même répartition de vitesse sur tout le diamètre d'ouverture;
• la turbine comporte des pales incurvées positionnées sur une base de forme essentiellement conique ou tronconique ;
• entre le cœur de l'enveloppe et la turbine, il y a un rétrécissement C restreignant le passage de l'air et obligeant l'air à pénétrer dans la turbine ;
• les pales de la turbine sont incurvées selon un angle ω compris entre 40 et 60°, de préférence entre 45 et 55°, et de manière particulièrement préférée entre 48 et 53° ;
• la turbine est entraînée par un moteur pouvant se loger au moins partiellement dans la partie creuse du cône supportant les pales de la turbine ;
• la région de réorganisation du flux (L-organiser) du sèche-cheveux comporte les ailettes de redressement du flux d'air à la sortie de la turbine ;
• le coude d'entrée d'air comporte sur sa paroi interne un moyen d'absorption du bruit sous forme de paroi comportant des ouvertures ;
• le moteur est du type moteur sans balais.

The preferred embodiments of the invention comprise at least one, or any suitable combination of the following characteristics:

• the air inlet elbow has between 3 and 6 blades, preferably 4 or 5 blades;
• the air inlet elbow further comprises one or more partitions dividing the blades;
• the outlet end of said air inlet elbow, at the inlet of the core of the envelope of the hair dryer, comprises a section restriction, compensating for the section occupied in said elbow by said blades;
• the distance between the blades is fixed in such a way that the air flow at the outlet of the air inlet elbow and at the inlet of the core of the envelope of the hair dryer has substantially the same speed distribution over the whole opening diameter;
• the turbine comprises curved blades positioned on a base of essentially conical or frustoconical shape;
• between the core of the casing and the turbine, there is a narrowing C restricting the passage of air and forcing the air to enter the turbine;
• the blades of the turbine are curved at an angle ω of between 40 and 60 °, preferably between 45 and 55 °, and particularly preferably between 48 and 53 °;
• the turbine is driven by a motor which can be housed at least partially in the hollow part of the cone supporting the blades of the turbine;
• the flow reorganization region (L-organize) of the hair dryer comprises the fins for rectifying the air flow at the outlet of the turbine;
• the air inlet elbow has on its internal wall a means of absorbing noise in the form of a wall comprising openings;
• the motor is of the brushless motor type.

By “generally” parallel, it is meant that the blades are substantially parallel to the curvature of the elbow. The more the blades are parallel to the curvature, the more the air inlet speed profile is linear over the entire width of the inlet diameter just before the turbine. The ideal position of the blades to reduce the noise of the flow is therefore this parallel position which must be approached as much as possible for an optimal result.

The terms “core of the envelope” and “region of reorganization of the flow” define regions of the tubular body of the hair dryer. According to the invention, the tubular body is composed of 3 regions. These are named, starting from the end of the body allowing the entry of air towards the end of air exit, the "heart of the envelope", the "flow reorganization region" and the "Air heating zone". The “core of the envelope” region (named “L-shroud” on the Figure 13 ) is the region comprising the turbine and which is attached to the outlet of the air inlet elbow. This region directs the air flow around the turbine. The “air flow reorganization” region (called “L-organize” on the Figure 13 ), is located at the outlet of the turbine 2, between the region of the core of the envelope and the air heating zone. It makes it possible to straighten, thanks to fins, the turbulent air flow leaving the turbine. Finally, the air flow enters the heating zone in order to be heated there before it leaves the appliance.

By “noise absorption means in the form of a wall”, it is meant that the various internal surfaces can comprise noise absorption means. The internal parts of the hair dryer can for example be coated or covered with noise-absorbing elements, or even with surface effects in the walls, such as perforations, openings, open-cell foam or non-woven fibers. -woven, etc.

Brief description of the figures

The figure 1 shows a three-dimensional view of the hair dryer according to the invention. The air inlet elbow is here integrated into a decorative element drawn in the open position.

The figure 2 shows a simplified drawing of the three-dimensional air inlet elbow with three blades. The part allowing the elbow to be opened is not shown for the sake of clarity of the figure.

The figures 3 and 4 represent the air inlet elbow in two parts with a central blade allowing the separation of the two elements constituting the air inlet elbow.

The figure 5 represents air intake elbows with blades varying in number and positioning. The figure shows examples with 3, 4 and 5 blades which are optimally positioned to generate an approximately linear air inlet speed profile over the entire width of the inlet diameter just before the turbine.

The figures 6 to 10 show different types of air inlet bends according to the invention. These can have shapes ranging from simple geometries to complex geometries that do not meet any precise geometric criteria.

The figure 11 shows an example of possible turbines according to the present invention.

The figure 12 shows the inner envelope of the housing of the hair dryer according to the present invention with fins for rectifying the air leaving the turbine. The inside of the shell can be lined with a noise absorption coating such as a perforated wall for example.

The figure 13 is a schematic representation of the hair dryer according to the invention which incorporates the main parameters influencing the air flow through the device.

The figure 14 is a sectional representation of a preferred embodiment of the hair dryer according to the invention.

List of reference symbols

1. 1. Hair dryer
2. 2. Turbine
3. 3. Air inlet elbow
4. 4. Air inlet elbow vanes
5. 5. Partition dividing the blades
6. 6. Turbine cone
7. 7. Handle
8. 8. Motor
9. 9. Blades
10. 10. Righting fins
11. 11. Restriction of section at the outlet of the elbow and at the inlet of the turbine

Detailed description of the invention

The present invention discloses a hair dryer 1 with improved sound performance comprising an air intake elbow 3 making it possible to reduce certain frequencies unpleasant to the ear, as well as the overall sound level up to 5 dB, preferably up to at 10 dB.

The figure 13 uses all the parameters defined for the construction of the hair dryer 1 according to the invention. To simplify the illustration of the invention, the apparatus has a symmetry of revolution about a central axis. he It is obvious that another configuration than that of symmetry of revolution about a central axis is also possible and can be envisaged according to the present invention. This is the reason why we will rather speak of a longitudinal axis.

The air inlet elbow 3 is compartmentalized by one or more blades 4 which substantially follow the curvature of the elbow 3. These blades are generally 3 to 6 in number. The best results have however been obtained with 4 or 5 blades. Although the air speeds are such as to obtain a Reynolds number classifying the flow thereof among the turbulent flows, the vanes 4 straighten the air flow to make it as laminar and parallel as possible before it does not enter the tubular body of the hair dryer 1. The blades (n = 1; 2; 3; 4; 5; 6 ...) also constitute a sound barrier between the turbine / engine compartment and the exterior of the hair dryer 1.

One or more partitions 5 dividing the curved blades 4 can also have a beneficial effect on the reduction of the sound level. A partition 5 vertically dividing the blades 4 also allows easier production of the manufacturing mold which avoids undercuts.

The air inlet elbow 3 can take different shapes and different regular or irregular curvatures, non-limiting examples are shown in figures 6 to 10 . When the elbow 3 is inscribed in a circle, the angle of the arc α formed by the air inlet elbow generally varies from 20 to 120 °, preferably from 25 to 90 °, or even from 30 to 80 ° and particularly preferably from 40 to 75 °. The axis of the radius of the air inlet elbow can be located close to or even away from the appliance, which directly influences the length of the elbow 3. The elbow 3 can also have a diameter varying over its length and that it can go up or down. All these parameters can obviously only vary by respecting the space constraints acceptable in practice for a hair dryer.

To straighten the air flow at the inlet of the turbine 2, the air inlet elbow 3 is compartmentalized by the presence of the blades 4. The distance between the blades 4 located in the air inlet elbow 3 is preferably chosen so that the pressure drop of the air flow through the compartments is the same, which makes it possible to obtain an almost homogeneous air speed profile over the entire section at air inlet, place where there is a section restriction 11 to compensate for the section occupied by the blades 4 and possible partitions 5, just in front of the turbine 2.

It is known that the pressure drop in a pipe for laminar flow depends at least on the length, the section and the perimeter as well as on the surface roughness, which is supposed to be the same for all the compartments. This pressure drop can be calculated by complex formulas including surface roughness, temperature, flow speed, etc. The formulas are generally reductive because they are based on simple geometries. In the present invention, however, we are not in the case of a laminar flow and profiles of homogeneous air velocities at the outlet of the elbow 3 compartmentalized by blades 4 could only be obtained experimentally by arranging the blades 4, and in particular the distances between blades, empirically by trial and error.

According to an example, the air inlet elbow 3 is defined in the following table. The value relates to the diameter D = 2R of the base of the cone 6 supporting the blades 9 of the turbine 2. (see Figure 13 or the radius of the cone is indicated) <b> Table 1: Air inlet elbow </b> Setting Value / D Dimension R inlet 0.36 23.5 mm r inlet 0.26 16.5 mm α 82.0 °

As already mentioned above, the air inlet in front of the turbine 2 also includes a section restriction 11 to compensate for the loss of section due to the presence of the blades 4 which reduce the effective diameter of the air inlet bend and which also constitute an obstacle to the flow of air at the inlet of the hair dryer, the aim being that the air flow does not enter a larger effective diameter after passing through the inlet elbow air 3.

The turbine 2 comprises curved blades 9 positioned on a base 6 of essentially conical or frustoconical shape (see Fig. 11 ). The level of curvature of the blades is determined by the angle ω (see Fig. 13 ). This angle generally varies from 20 to 50 °, preferably from 25 to 40 ° or from 28 to 37 °, and in a particularly preferred manner from 30 to 35 °.

The cone 6 supporting the blades 9 is defined in particular by the angle θ1 formed with respect to the central axis. It can vary from 45 to 65 °, preferably from 50 to 60 °, and particularly preferably from 53 to 58 °.

A non-limiting example of a turbine 2 for a specific embodiment of a hair dryer 1 is given in the following table. It gives dimension reports and an example of actual dimension for the execution mode shown in the figure 13 with a straight cone 6 and a shrinkage C of the envelope around the turbine 2: <b> Table 2: Turbine </b> Setting Value / D Dimension R 0.50 32.2 mm r _i 0.12 7.5 mm r _o 0.56 36.3 mm h 0.48 31.0 mm θ1 55.6 ° θ2 10.6 ° ω 50 ° r _i = the minimum radius of the lower edge of the turbine blades
r _o = the maximum external radius
h = maximum height of the blade from the base of the cone
θ = semi-angle of the cone relative to the longitudinal axis of the hairdryer
ω = angle of inclination of the pale relative to the radial direction

The turbine 2 is driven by a motor 8 which can be housed at least partially in the hollow part of the cone 6 supporting the blades 9 of the turbine 2. Preferably, a brushless motor 8 will be used which will be less noisy than an ordinary motor .

The core of the envelope is the region defined by the outlet of the air inlet elbow (L-shroud) before the reorganization of the air flow (L-organizer) at the outlet of the turbine 2. This area is very important. It comprises the turbine 2 and determines the air flow around it. According to a nonlimiting example, the core of the envelope is defined as follows: <b> Table 3: Heart of the envelope </b> Setting Value / D Dimension L shroud 0.69 44.7 mm R shroud 0.72 46.6 mm S 0.10 6.6 mm VS 0.031, 0.5 or 0.093 2, 4 or 6 mm (TBD)

At the outlet of turbine 2, the air flow is very turbulent, which is unfavorable to the objective of reducing noise. For this reason, the region of reorganization of the flow (L-organize), which begins at the exit of the core of the envelope (L-shroud) and goes to the entry of the air heating zone (L-heater), includes fins 10 for rectifying the air flow at the outlet of the turbine 2. These fins 10 are curved towards the direction of introduction of the air leaving the turbine 2 (see Fig. 12 ).

The fins have an angle φ with respect to the plane which passes through the central axis of approximately 45 ° (see Figure 13 ). The function of these fins 10 is to reduce the rotational air flow around the central axis without adding substantial turbulence.

According to a nonlimiting example, the region of reorganization of the flow is defined as follows: <b> Table 4: Region of reorganization of the flow </b> Set up Value / D Dimension Organize it 0.90 58.0 mm W-blade 0.33 21.0 mm φ 45.0 °

The region where the air is heated (L-heater) has heating resistors and their support structure. This region begins at the end of the flow reorganization region (L-organize) up to the exit plane of the device. Insofar as this region is of frustoconical shape and characterized by a reduction in diameter at an angle β relative to the central axis, it accelerates the air flow. <b> Table 5: Heating zone </b> Setting Value / D Dimension L-heater 1.21 78.2 mm R-out 0.28 17.9 mm β 11.6 °

Different interior parts of the housing of the hair dryer according to the invention and in particular of the air inlet elbow 3 can be upholstered with surfaces or walls absorbing the noise of the air flow and of the turbine 2. These surfaces can be of the perforated partition, open-cell foam or non-woven fibers type, etc.

Claims (12)

1. A hair dryer (1) comprising:

   - a tubular body along a longitudinal axis with, at its opposite ends, an air inlet and an air outlet;

   - an impeller (2) located in said tubular body which, in use, is driven in rotation by a motor (8) in the direction of the longitudinal axis, which makes it possible to suction the air through the inlet and expel the air through the outlet of said tubular body, characterized in that the hairdryer (1) comprises:
   an air intake bend (3) comprising one or more vanes (4) that are globally parallel to the curve of the bend (3).
2. The hair dryer according to claim 1, wherein the air intake bend (3) comprises between 3 and 6 vanes (4), preferably 4 or 5 vanes (4).
3. The hair dryer according to any one of the preceding claims, characterized in that the air intake bend (3) further comprises one or more partitions (5) dividing the vanes (4).
4. The hair dryer according to any one of the preceding claims, characterized in that the outlet end of said air intake bend (3), at the entrance of the core of the hair dryer shroud, comprises a section constriction (11), compensating for the section occupied in said bend (3) by said vanes (4).
5. The hair dryer according to any one of the preceding claims, characterized in that the distance between the vanes (4) is set such that the air flow at the outlet of the air intake bend (3) and at the entrance of the core of the hair dryer (1) shroud has substantially the same speed distribution over the entire opening diameter.
6. The hair dryer according to any one of the preceding claims, characterized in that the impeller (2) comprises curved blades (9) positioned on a substantially conical or frustoconical base.
7. The hair dryer according to any one of the preceding claims, characterized in that between the core of the shroud and the impeller (2), there is a constriction C restricting the passage of air and forcing the air to enter the impeller (2).
8. The hair dryer according to any one of the preceding claims, characterized in that the blades (9) of the impeller (2) are curved at an angle ω between 40 and 60°, preferably between 45 and 55°, and particularly preferably between 48 and 53°.
9. The hair dryer according to any one of the preceding claims, characterized in that the blades of the impeller (2) are supported by a cone (6), and in that the impeller (2) is driven by a motor (8) that can be housed at least partially in the hollow portion of the cone (6).
10. The hair dryer (10) according to any one of the preceding claims, characterized in that the hair dryer comprises a region for reorganizing the flow including fins (10) for straightening the flow of air at the outlet of the impeller (2).
11. The hair dryer according to any one of the preceding claims, wherein the air intake bend (3) comprises, on its inner wall, a sound absorption means in the form of a wall including openings.
12. The hair dryer according to any one of the preceding claims, wherein the motor (8) is of the brushless motor type.

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