AU2014389903A1

AU2014389903A1 - A hairdryer

Info

Publication number: AU2014389903A1
Application number: AU2014389903A
Authority: AU
Inventors: Stephen Courtney; Peter Gammack; Patrick MOLONEY; Edward Shelton
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2014-04-03
Filing date: 2014-04-03
Publication date: 2016-09-22
Also published as: CN207767746U; KR20180003197U; JP2017512589A; KR20190001036U; AU2018100162A4; AU2016101876A4; AU2016102122A6; AU2018101206B4; AU2018101095A4; CN208144696U; AU2018101206A4; AU2018100160B4; AU2018100157A4; AU2018100160A4; KR200490784Y1; KR20180003187U; JP6475261B2; AU2018100157B4; AU2017100592A4; AU2018100161A4

Abstract

Disclosed is a hairdryer (10) comprising a primary fluid flow path (400) extending from a primary fluid (40) inlet to a primary fluid outlet (440), a fan (70) unit for drawing primary fluid into the primary fluid flow path, a heater (80) for heating primary fluid in the primary fluid flow path wherein primary fluid flowing through the heater has a lower velocity than primary fluid flowing through the fan unit. The heater may be downstream of the fan unit. The cross sectional area of the primary fluid flow path may vary along the primary fluid flow path. The cross sectional area of the primary fluid flow path may be greater around the heater than around the fan unit. The hairdryer may comprise a handle and the primary fluid inlet is in the handle (20). The hairdryer (10) may comprise a body (30) and the primary fluid outlet is in the body and the primary fluid flow path extends within the handle from the primary fluid inlet to the body.

Description

A Hairdryer

This invention relates to a hand held appliance, in particular a hair care appliance such as a hairdryer or hot styling brush.

Blowers and in particular hot air blowers are used for a variety of applications such as drying substances such as paint or hair and cleaning or stripping surface layers. In addition, hot air blowers such as hot styling brushes are used to style hair from a wet or dry condition.

Generally, a motor and fan are provided which draw fluid into a body; the fluid may be heated prior to exiting the body. The motor is susceptible to damage from foreign objects such as dirt or hair so conventionally a filter is provided at the fluid intake end of the blower. Conventionally such appliances are provided with a nozzle which can be attached and detached from the appliance and changes the shape and velocity of fluid flow that exits the appliance. Such nozzles can be used to focus the outflow of the appliance or to diffuse the outflow depending on the requirements of the user at that time.

According to a first aspect, the invention provides a hairdryer.

In a preferred embodiment, the hairdryer comprises a primary fluid flow path extending from a primary fluid inlet to a primary fluid outlet, a fan unit for drawing primary fluid into the primary fluid flow path, a heater for heating primary fluid in the primary fluid flow path wherein primary fluid flowing through the heater has a lower velocity than primary fluid flowing through the fan unit.

Preferably, the heater is downstream of the fan unit.

In a preferred embodiment, the cross sectional area of the primary fluid flow path varies along the primary fluid flow path.

Preferably, the cross sectional area of the primary fluid flow path is greater around the heater than around the fan unit.

In a preferred embodiment, the hairdryer comprises a handle wherein the primary fluid inlet is in the handle.

Preferably, the hairdryer comprises a body and the primary fluid outlet is in the body wherein the primary fluid flow path extends within the handle from the primary fluid inlet to the body.

In a preferred embodiment, the fan unit is located in the handle.

Preferably, the handle is substantially orthogonal to the body.

In a preferred embodiment, the primary fluid flow path flows in a first direction within the handle and a second direction within the body.

Preferably, the first direction is substantially orthogonal to the second direction.

In a preferred embodiment, primary fluid flowing through the primary fluid outlet has a higher velocity than primary fluid flowing through the heater.

Preferably, primary fluid flowing into the primary fluid inlet has a similar velocity to primary fluid flowing through the heater.

In a preferred embodiment, the velocity of primary fluid increases from the primary fluid inlet to the fan unit.

Preferably, the velocity of primary fluid decreases from the fan unit towards the body.

In a preferred embodiment, the hairdryer comprises a fluid flow path that extends from a fluid inlet into the body to a fluid outlet from the body.

Preferably, within the body the primary fluid flow path surrounds the fluid flow path.

In a preferred embodiment, the body comprises an inner duct which separates the primary fluid flow path and the fluid flow path.

Preferably, the heater surrounds the inner duct.

In a preferred embodiment, the heater extends along the inner duct.

It is preferred that the hairdryer comprises a high speed motor. The hairdryer comprises a fan unit for creating an air current, the fan unit comprising an air inlet, an air outlet, an impeller and a motor for rotating the impeller to create an air flow passing from the air inlet to the air outlet, wherein the motor has a rotor which, in use, is capable of rotating at a speed of at least 50,000 rpm. Preferably, the rotor is capable of rotating at a speed of at least 80,000 rpm. It is preferred that the rotor is capable of rotating at a speed of up to 110,000 rpm. Preferably, the hairdryer is an amplifying hairdryer, thus the fan unit does not process all of the flow that exits from the hairdryer i.e. some flow through the hairdryer is entrained by fluid drawn into the hairdryer by the action of the motor. Preferably the fan unit is housed within a handle of the hairdryer.

The invention provides a hairdryer comprising a fan unit including a high pressure motor. Preferably, the pressure generated by the motor is between 1400 and 2250Pa. For a motor sitting within a cross sectional area of 25mm2 this equates to a flow rate of 9.4 to 12 1/s and a motor speed of 84,000 to 105,000rpm. Thus the motor resides within a grippable handle, preferably having a diameter of 35 to 42mm.

According to the invention, the thickness of the outer wall is preferably less than 2mm and more preferably less than 1mm thick. Ideally the thickness is around 0.7mm.

In another aspect, the handle diameter is between 20 and 60 mm and is preferably between 30 and 50mm. Most preferably, the handle diameter is between 35 and 42mm.

According to the invention a hairdryer has handle comprising a motor and a wall of the handle is lined with material. Typically, the lining material is between 4 and 6mm thick.

According to the invention a hairdryer comprises a handle which houses a fan unit and the handle is lined with a lining material. The lining material preferably comprises at least one of an inlet silencer and an outlet silencer. It is preferred that the length of the outlet silencer So from a downstream end of the fan unit to a downstream end of the handle 20 is up to 100mm long. It is preferred that the inlet silencer Si from an upstream end of the fan unit to a downstream end of the inlet is 10 -200mm long. It is preferred that the ratio between the inlet silencer Si and the outlet silencer So is greater than 1.2. In a hairdryer 10 having a constant diameter handle 20, the ratio is preferably greater than 0.1.

According to the invention, the length Lx of the body from the fluid inlet to an upstream edge of the handle and the length Lz of the body from a downstream edge of the handle to the fluid outlet at the downstream end of the body has a relationship. Ideally Lz < 40mm and Lx < 20mm. Preferably, 2Lx=Lz.

According to the invention, the hairdryer has a relationship between the diameter da of the outer wall of the body and the diameter db of the inner duct. The ratio of db: da is preferably between 0.49 and 0.6 in a hairdryer having a constant diameter handle.

According to the invention, the ratio of db: da is preferably between 0.4 and 0.9 in a hairdryer having a non constant or varying diameter handle.

According to the invention, the hairdryer has a relationship between the length 12 of the body and the diameter dh of the handle. The ratio off: dh is preferably between 1.9 and 2.5 in a hairdryer having a constant diameter handle. The ratio of 12: dh is preferably between 1.9 and 2.5 in a hairdryer having a non constant or varying diameter handle.

According to the invention, the hairdryer has a relationship between the diameter da of the outer wall of the body and the diameter dh of the handle. The ratio of da: dh is preferably between 1.6 and 3.4 in a hairdryer having a constant diameter handle.

According to the invention, the hairdryer has a relationship between the length 12 of the body and the diameter da of the body. The ratio of 12: da is preferably between 1.1 and 1.6 in a hairdryer having a fan unit in the handle. For a hairdryer where the heater is in the body and the fan unit in the handle, the ratio of 12: da is preferably between 0.8 and 1.6.

According to the invention, the hairdryer has a relationship between the length 12 of the body and the diameter db of the inner duct. The ratio of 12: db is preferably between 1.8 and 3.4. For hairdryers where the heater is in the body and the fan unit in the handle, the ratio of 12: da is preferably between 1 and 3.4.

According to the invention, the hairdryer has an inner duct connected to an outer wall via a side wall. In one embodiment the side wall is orthogonal to the outer wall.

According to the invention, the hairdryer comprises a handle and a body wherein, flow in the primary fluid flow path in the body is at 90° to the flow in the primary fluid flow path in the handle. Preferably, the primary fluid flow within the body is parallel with the fluid that flows through a fluid flow path.

According to the invention, the hairdryer comprises a body having an inner duct comprising a conical part and a tubular part wherein the radius r between the conical part and the tubular part of the inner duct lies between 0.5 and 50mm.

According to the invention, the hairdryer comprises a body having an inner duct comprising a conical part and a tubular part wherein the conical part at least partially defines a fluid inlet and the tubular part at least partially defines a fluid outlet wherein the inner duct increases in diameter from the conical part towards the fluid outlet.

According to the invention, the hairdryer comprises a body comprises an outer wall, an inlet end and an outlet end wherein a chamfer is provided at the outlet end wherein at the chamfer the diameter of the outer wall decreases towards the centre A—A of the outer wall and wherein the chamfer is between 30° and 60°. Ideally the chamfer is between 30° and 60°. Preferably, a front chamfer of 35 to 55° and more preferably, a front chamfer of 45° is provided.

According to the invention, a hairdryer having a body comprising a primary fluid outlet defined by a first surface and a second surface of the body wherein , the first surface and second surface are substantially parallel surfaces defining and outer annular limit and an inner annular limit respectively for the primary fluid outlet. Preferably, the body comprises an inner duct and the first surface and second surface are additionally substantially parallel with the inner duct.

According to the invention, a hairdryer having a body comprising a primary fluid outlet defined by a first surface and a second surface of the body wherein , the first surface and second surface are substantially parallel surfaces defining and outer annular limit and an inner annular limit respectively for the primary fluid outlet. Preferably, the body comprises an inner duct and the first surface and second surface are additionally inclined towards the inner duct adjacent the primary fluid outlet.

According to the invention,, a hairdryer having a body comprising a primary fluid outlet defined by a first surface and a second surface of the body wherein , the first surface and second surface are substantially parallel surfaces defining and outer annular limit and an inner annular limit respectively for the primary fluid outlet. Preferably, the body comprises an inner duct and the first surface and second surface are additionally inclined away from the inner duct adjacent the primary fluid outlet.

According to the invention, a hairdryer comprises a body having a tubular outer wall and a handle substantially orthogonal to the body having a fluid inlet at least partially defined by a side wall that extends from the tubular outer wall towards a centre of the tubular outer wall wherein the side wall is angled at between 1 and 90° to the tubular outer wall. Preferably, the angle is between 30 and 60°. More preferably, the angle is 45°.

The invention will now be described by way of example, with reference to the accompanying drawings, of which:

Figure 1 shows a perspective view of a hairdryer according to the invention;

Figure 2 shows a cross section through the hairdryer of Figure 1;

Figure 3a shows a side view of the inner wall of a hairdryer;

Figure 3b shows across section through the inner duct of a hairdryer;

Figure 4 shows a side view of a hairdryer;

Figure 5 shows a rear end view of a hairdryer;

Figure 6 shows another side view of a hairdryer;

Figure 7 shows a front end view of a hairdryer;

Figure 8 shows a bottom view of a hairdryer;

Figure 9 shows a rear perspective view of a hairdryer;

Figure 10 shows a graph of length of silencers in a handle of a hairdryer;

Figures 1 la to lid show end views of alternative hairdryers according to the invention;

Figure 12 shows a side view of a hairdryer according to the invention;

Figures 13a and 13b show side views of hairdryers according to the invention;

Figures 14a and 14b show end views of some other hairdryers according to the invention;

Figures 15a, 15b and 15c show side views of some hairdryers according to the invention;

Figures 16a, 16b, 16d and 16e show side views of alternative hairdryers according to the invention;

Figures 16c and 16f show corresponding end views of the alternative hairdryers of Figures 16a, 16b, 16d and 16e;

Figure 17a shows a side view through a hairdryer according to the invention;

Figures 18a to 18d show side views through other hairdryers according to the invention;

Figures 19a and 19b show alternate front chamfers for a hairdryer according to the invention;

Figures 20a to 20c show alternative outlet arrangements for a hairdryer according to the invention;

Figure 21 shows a side view through a hairdryer in use;

Figure 22a shows a graph of velocity profile through a hairdryer according to the invention; and

Figure 22b shows schematically the cross sectional area of the primary fluid flow path.

Figures 1 and 2 show a hairdryer 10 with a handle 20 and a body 30. The handle has a first end 22 which is connected to the body 30 and a second end 24 distal from the body 30 and which includes a primary fluid inlet 40. Power is supplied to the hairdryer 10 via a cable 50.

The body 30 has a first end 32 and a second end 34 and can be considered to have two parts. A first part 36 which extends from the first end 32 which is generally tubular and a second part 38 which extends from the second end 34 to join the first part 36. The second part 38 is cone shaped and varies in diameter along its length from the diameter of the first part 36 of the body 30 to a smaller diameter at the second end 34 of the body. In this example, the second part 38 has a constant gradient and the angle a subtended from the outer wall 360 of the first part 36 of the body 30 in this example is around 40°.

The handle 20 has an outer wall 200 which extends from the body 30 to a distal end 24 of the handle. At the distal end 24 of the handle an end wall 210 extends across the outer wall 200. The cable 50 enters the hairdryer through this end wall 210. The primary fluid inlet 40 in the handle 20 includes first apertures that extend around and along 42 the outer wall 200 of the handle and second apertures that extend across 46 and through the end wall 210 of the handle 20. The cable 50 is located approximately in the middle of the end wall 210 so extends from the centre of the handle 20. The end wall 210 is orthogonal to the outer wall 200 and an inner wall 220 of the handle.

Upstream of the primary fluid inlet 40, a fan unit 70 is provided. The fan unit 70 includes a fan and a motor. The fan unit 70 draws fluid through the primary fluid inlet 40 towards the body 30 through a primary fluid flow path 400 that extends from the primary fluid inlet 40 and into the body 30 where the handle 20 and the body 30 are joined 90. The primary fluid flow path 400 continues through the body 30 towards the second end 34 of the body, around a heater 80 and to a primary fluid outlet 440 where fluid that is drawn in by the fan unit exits the primary fluid flow path 400. The primary fluid flow path 400 is non linear and flows through the handle 20 in a first direction and through the body 30 in a second direction which is orthogonal to the first direction.

The body 30 includes an outer wall 360 and an inner duct 310. The primary fluid flow path 400 extends along the body from the junction 90 of the handle 20 and the body 30 between the outer wall 360 and the duct 310 towards the primary fluid outlet 440 at the second end 34 of the body 30.

Another fluid flow path is provided within the body; this flow is not directly processed by the fan unit or the heater but is drawn into the hairdryer by the action of the fan unit producing the primary flow through the hairdryer. This fluid flow is entrained into the hairdryer by the fluid flowing through the primary fluid flow path 400.

The first end 32 of the body includes a fluid inlet 320 and the second end 34 of the body includes a fluid outlet 340. Both the fluid inlet 320 and the fluid outlet 340 are at least partially defined by the duct 310 which is an inner wall of the body 30 and extends within and along the body. A fluid flow path 300 extends within the duct from the fluid inlet 320 to the fluid outlet 340. At the first end 32 of the body 30, a side wall 350 extends between the outer wall 360 and the duct 310. This side wall 350 at least partially defines the fluid inlet 320. At the second end 34 of the body a gap is provided between the outer wall 360 and the duct, this gap defines the primary fluid outlet 440. The primary fluid outlet 440 is annular and surrounds the fluid flow path. The primary fluid outlet 440 may be internal so the primary fluid flow path 400 merges with the fluid flow path 300 within the body 30. Alternatively, the primary fluid outlet 440 is external and exits from the body 30 separately to the fluid from the fluid flow path 300 at the fluid outlet 340.

The outer wall 360 of the body converges towards the duct 310 and a centre line A-A of the body 30. Having an outer wall 360 that converges towards the duct 310 has the advantage that the primary flow exiting the primary fluid outlet 440 is directed towards the centre line A-A of the body 30. The fluid exiting the primary fluid outlet 440 will cause some external entrainment of fluid 490 from outside the hairdryer due to the movement of the fluid from the primary outlet 440. This effect is increased by the outer wall 360 converging towards the duct 310. Partly this is because the primary flow is focused rather than divergent and partly this is because of the slope of the outer wall 360 of the body 30 towards the second end 34 of the hairdryer.

The duct 310 is an internal wall of the hairdryer that can be accessed from outside the hairdryer. Thus, the duct 310 is an external wall of the hairdryer. The duct 310 is recessed within the body 30 so the side wall 350 that connects between the outer wall 360 and the duct 310 is angled with respect to the outer wall 360. A PCB 75 including the control electronics for the hairdryer is located in the body 30 near the side wall 350 and fluid inlet 320. The PCB 75 is ring shaped and extends round the duct 310 between the duct 310 and the outer wall 360. The PCB 75 is in fluid communication with the primary fluid flow path 400. The PCB 75 extends about the fluid flow path 300 and is isolated from the fluid flow path 300 by the duct 310.

The PCB 75 controls such parameters as the temperature of the heater 80 and the speed of rotation of the fan unit 70. Internal wiring (not shown) electrically connects the PCB 75 to the heater 80 and the fan unit 70 and the cable 50. Control buttons 62, 64 are provided and connected to the PCB 75 to enable a user to select from a range of temperature settings and flow rates for example.

In use, fluid is drawn into the primary fluid flow path 400 by the action of the fan unit 70, is optionally heated by the heater 80 and exits from the primary fluid outlet 440.

This processed flow causes fluid to be entrained into the fluid flow path 300 at the fluid inlet 320. The fluid combines with the processed flow at the second end 34 of the body. In the example shown in Figure 2, the processed flow exits the primary fluid outlet 440 and the hairdryer as an annular flow which surrounds the entrained flow that exits from the hairdryer via the fluid outlet 340. Thus fluid that is processed by the fan unit and heater is augmented by the entrained flow.

The handle 20 has an outer wall 200 and an inner wall 250 which at least partially defines the primary fluid flow path 400 through the handle 20. The inner wall 250 extends from the body 30 to a downstream end 254 towards the second end 24 of the handle 20. The handle 20 is tubular and the outer wall 200 of the handle 20 is a cylindrical sleeve made from any suitable material such as moulded plastic or a rolled sheet of metal such as aluminium, an aluminium alloy or a steel. The handle connects to the body 30 at a first end 22 and at the distal, second end 24 a primary fluid inlet 40 is provided. The primary fluid inlet 40 is a first means of filtering fluid that enters the primary fluid flow path 400.

Referring now to Figure 3, a lining material 270 is positioned between the inner wall 250 and the outer wall 200. The lining material 270 is a foam or a felt which at least attenuates noise (has a silencing effect) produced when fluid is drawn into the handle 20 by the fan unit 70. For clarity, the lining material 270 has been shown around only a part of the inner wall 250. To enable contact between the lining material 270 and the fluid flowing in the primary fluid flow path 400 and thus attenuation of noise, the inner wall 250 is provided with perforations 256 that extend around and at least partially along the length of the inner wall 250.

The lining material 270 is provided to reduce noise produced when fluid is drawn into the primary fluid inlet 40 by the action of the fan unit 70.

The perforations 256 of the inner wall 220 are of a diameter which is chosen to attenuate noise most effectively. Diameters of 1mm to 10mm are suitable; the smaller diameters being better for obtaining a good sound power (reducing sound over the main human sound range) and the larger diameters are good for high frequency attenuation. The perforations preferably form at least 40% of the surface area of the inner wall 220, 250.

By having the lining material 270 disposed behind the inner wall 250 one is able to use a greater thickness of lining material than if the lining material 270 was directed exposed to the primary fluid flow path. This is because the diameter of the primary fluid flow path 400 is determined by the inner wall 250 which squashes the lining material 270 in to the gap between the inner wall 250 and the outer wall 200 of the handle 20. Typically, the lining material is between 4 and 6mm thick but will be compressed between the outer wall 200 and the inner wall 250.

An important feature of having a multi layered handle 20 is that the material properties can be used to improve the mitigation of noise produced by the product. Airborne noise produced by the fan unit 70 and fluid flowing into the primary fluid flow path 400 is attenuated by the lining material 270; however some noise is transmitted through the lining material 270.

An additional feature required by the handle 20 is for it to be of sufficient stiffness to provide a grippable handle which will not readily bend which would introduce a restriction into the primary fluid flow path. Thus, materials such as aluminium or carbon a fibre reinforced composite are ideal as they provide a lightweight and stiff tube. Alternatively the outer wall is produced from a plastic material. The skilled person will be aware that there are other materials that would provide similar benefits.

In order that the handle 20 diameter is not overly large for a user, the thickness of the outer wall 200 is preferably less than 2mm and more preferably less than 1mm thick. Ideally the thickness is around 0.7mm. Having a relatively thin outer wall 200 of the handle 20 also reduces the weight of the product.

When you have a high speed motor the noise produced is at high frequencies, some of which can be irritating to the human ear. However, this has an advantage as one is able to attenuate the higher frequencies more effectively.

The handle diameter is ideally between 20 and 60 mm and is preferably between 30 and 50mm. Most preferably, the handle diameter is between 35 and 42mm. In order to maximise the mitigation of noise and provide a grippable handle, the inventors have used a combination of materials in the handle 20. Firstly the outer layer 200 which is rigid but also thin so that the sound attenuation within the handle 20 by the silencing media namely lining material 270 can be maximised by maximising the thickness of the lining material 270 within the handle 20. Ideally at least 6mm of lining material 270 or silencing media is required to attenuate the higher frequency noises (typically around 1.8 to 2Khz) produced by a high speed motor.

Referring now to Figure 7, the length of the lining material 270 is also important. Ideally there is lining material 270 both upstream of and downstream of the motor 70; this is because the motor generates noise when fluid enters the motor and when fluid exits the motor.

Referring now to Figure 10 which shows a graph of noise produced by the high speed motor within a handle 20 in relation to the distance of the fan unit 70 from the inlet 40. Generally, the longer the length of the lining silencing material the more sound is attenuated but, there is a limit to how long a product can be and still be practical. Thus for a hairdryer having a motor in the handle 20 there is an optimum position between for the motor within the length of a handle from a noise perspective. The longer the inlet silencer the more noise is attenuated as can be seen on the graph as the motor moves away from the inlet, along the x-axis the inlet 280 noise decreases. However, for a given handle length lh the longer the inlet silencer Si the shorter the outlet silencer So must be.

For the outlet silencer So if the motor is located at the inlet (the zero value of the x-axis) the outlet noise level 282 for the outlet silencer So is minimised for a given handle length lh then, as the motor moves along the handle the outlet silencer So reduces in length and the noise attenuation decreases so the sound level rises. There is therefore an optimum distance for the motor from the inlet. In the amplifying hairdryer where the primary fluid flow path 400 flows from the handle 20 into the body 30 there is a change in the shape and size of the primary fluid flow path from a circular cross section 400a within the handle to an annular or doughnut cross section 400b within the body. For this reason the inlet and outlet silencers within the handle are not equal from a sound perspective as some of the noise created by fluid exiting the motor is attenuated by the fluid passing into the body 30.

The combined noise output 284 from both the inlet silencer Si and the outlet silencer So is the compressor value on the graph which decreases initially as the motor is moved away from the inlet to reach a sweet point where the noise levels of the inlet silencer Si and the outlet silencer So cross before rising again.

The total noise output 288 for the hairdryer is the addition of the compressor value 284 and the amplifier value 286 which is the noise produced within the body 30 of the hairdryer and this value is unaffected by the position of the motor within the handle 20. For this particular hairdryer 10, the optimum inlet silencer Si is 70 to 100mm. However, if for example any of the motor speed, the diameter of the handle, or inlet features is changed, this value will change.

It is preferred that the length of the outlet silencer So from the downstream end 70b of the fan unit 70 to the downstream end 22 of the handle 20 is up to 100mm long. It is preferred that the inlet silencer Si from the upstream end 70a of the fan unit to the downstream end 40b of the inlet 40 is 10 -200mm long. It is preferred that the ratio between the inlet silencer Si and the outlet silencer So is greater than 1.2. In a hairdryer 10 having a constant diameter handle 20, the ratio is preferably greater than 0.1.

Referring now to Figures 5, 1 la to lid, the hairdryer 10 has a relationship between the diameter da of the outer wall 360 of the body 30 and the diameter db of the inner duct 310. The ratio of db: da is preferably between 0.49 and 0.6 in a hairdryer 10 having a constant diameter handle 20 as show in Figures 11c and lid. The ratio of db: da is preferably between 0.4 and 0.9 in a hairdryer 130 having a non constant or varying diameter handle 132 as shown in Figures 11a and 1 lb.

Referring now in particular to Figure 12, the relationship between the length Lx of the body 30 from the fluid inlet 320 to an upstream edge 202 of the handle 20 and the length Lz of the body 30 from a downstream edge 204 of the handle 20 to the fluid outlet 340 at the downstream end of the body 30 has a relationship. Ideally Lz < 40mm and Lx < 20mm. Preferably, 2Lx=Lz.

Referring now to Figures 13a and 13b hairdryers 132, 134 have a relationship between the length 12 of the body 30 and the diameter dh of the handle 20. The ratio of F: dh is preferably between 1.9 and 2.5 in a hairdryer 10 having a constant diameter handle 20. The ratio of 12: dh is preferably between 1.9 and 2.5 in a hairdryer 160, 162 having a non constant or varying diameter handle 164 as shown in Figures 13c and 13d.

Referring now to Figures 14a and 14b, hairdryers 136,138 have a relationship between the diameter da of the outer wall 360 of the body 30 and the diameter dh of the handle 20. The ratio of da: dh is preferably between 1.6 and 3.4 in a hairdryer 10 having a constant diameter handle 20.

Referring now to Figures 15a to 15c, hairdryers 140 and 142 have a relationship between the length 12 of the body 30 and the diameter da of the body 30. The ratio of 12: da is preferably between 1.1 and 1.6 in a hairdryer 10 having a fan unit 70 in the handle 20. For a hairdryer 144 where the heater 80 is in the body 30 and the fan unit 70 in the handle 20 as shown in Figure 15c, the ratio of 12: da is preferably between 0.8 and 1.6.

Referring now to Figures 16a to 16c hairdryers 146, 148 have a relationship between the length 12 of the body 30 and the diameter db of the inner duct 310. The ratio of F: db is preferably between 1.8 and 3.4. Referring now to Figures 16cd to 16f, for hairdryers 150, 152 where the heater 80 is in the body 30 and the fan unit 70 in the handle 20, the ratio of 12: da is preferably between 1 and 3.4.

Another feature of the invention is that the flow in the primary fluid flow path 400b in the body 30 is at 90° to the flow in the primary fluid flow path 400a in the handle 20. The primary fluid flow within the body 30 is parallel with the fluid that flows through the fluid flow path 300.

Referring now to Figures 2, 3b and 9, the inner duct 310 has a generally tubular part 312 extending from the fluid outlet 340 towards the fluid inlet 320 and a generally conical part 314 that forms a side wall 350 that connects between the generally tubular part 312 and the outer wall 360 of the body 30.

The side wall 352 could be orthogonal to the outer wall 360 as shown in Figure 17a. Indeed, a separate side wall 350, 352 could be dispensed with and the inner duct 354 could extend from the fluid inlet 320 as a cylinder with gradually decreasing diameter towards the fluid outlet 340, in the form of a truncated cone.

Referring to Figure 18a, the inner duct 354a extends from the outer wall 360 at the first end 32 and curves towards a tube forming a circular duct at the second end 36. The form generated by inner duct 354a is trumpet shaped. Figure 18b shows a similar inner duct 354b to that of Figure 18a however the cone part 358 of the inner duct 354b is shorter giving a steeper gradient to the fluid inlet 320.

The gradually curving inner duct has benefits in that noise is reduced as there is less turbulence created as fluid enters the fluid flow path at the fluid inlet 320. Having a curved side wall is acoustically beneficial as flow entrained into the fluid flow path 300 does not encounter any sharp corner which would introduce eddies and increase the generation of noise. The side wall is blended into the tubular part of the inner duct 310

Figure 18c shows a combination of the inner duct 354a of Figure 18a and a flared bore 354c. The inner duct extends 362 from the first end 32 to a transition point 364 where the cylinder with gradually decreasing diameter changes to slightly increase in diameter towards the second end 34. This flaring of the inner duct increases entrainment of fluid into the fluid inlet 320.

Figure 18d shows a combination of the cone part 358 of Figure 18b and a flared inner duct 354d. By having a shorter cone region of the inner duct 354d, the flare can be longer.

In fact any angle between 1 and 90° could be selected for the angle β between the outer wall 360 and the inner duct 350, 354a, 354b, 354c and 354d.

Referring to Figures 18c and 18d in particular, the radius r between the conical part 358,362 and the tubular part 312 of the inner duct 354d, 354c can be varied. The radius preferably lies between 0.5 and 50mm.

Alternatively, the inner duct 310 could increase in diameter from the side wall 366 towards the fluid outlet 340, as is shown in Figures 17b and 17c. This is advantageous because it increases the entrained flow through the fluid flow path 300. Thus, either the total emission of fluid from the fluid outlet 340 and the primary fluid outlet 440 is increased, of the fan unit can be run at slower speeds to produce an equivalent total output, reducing noise of the product. The increase in diameter of the inner duct 310 is more pronounced in Figure 17c which results in more entrainment through the inner duct 310.

Referring now to Figure 7, the length of the lining material within the handle 20 can be varied. It is preferred that the length of the inlet lining Si from the downstream end 40b of the inlet 40 to the upstream end 70a of the fan unit 70 is between 10 and 200mm.

The front part 38 (Figure 2) of the hairdryer can have various chamfers 372, 374, 376 as shown in Figures 1,2, 6, 19a and 19b the front chamfer 372, 374, 376 is a change in the diameter of the outer wall 360 of the body 30. The diameter decreases towards the centre A—A of the outer wall 360. The front chamfer 372, 374, 376 influences external entrainment 490 from outside the hairdryer due to movement of fluid from the primary outlet 440. A blunt front face for the body 30 would restrict flow both for the external entrainment 490 and for flow through the fluid flow path 300. Ideally a front chamfer of between 30° as shown in Figure 19a and 60° as shown in Figure 19b is selected. Preferably, a front chamfer of 35 to 55° and more preferably, a front chamfer of 45° is provided as this provides a reasonable amount of external entrainment 490.

The direction of flow exiting the primary fluid outlet is variable depending on the desired outcome. Figures 20a, 20b and 20c show different air exits for the primary fluid. Referring firstly to Figure 20a, the primary fluid outlet 440 has first 442 and second 444 substantially parallel surfaces defining and outer annular limit and an inner annular limit respectively for the primary fluid outlet 440. The first 442 and second 444 substantially parallel surfaces are additionally substantially parallel with the inner duct 310. This arrangement provides a balance between externally entrained flow 490 and internally entrained fluid 492 namely that which is drawn into the fluid flow path 300.

In Figure 20b, the primary fluid outlet 440a is directed towards the centre of the outer wall 360 of the body 30. In this example, both the first 446 and the second 448 surfaces that define the primary fluid outlet 440a are substantially parallel to each other but are inclined to the inner duct 310. The primary fluid outlet 440a is directed towards the inner duct 310 and the centre of the outer body 360. Fluid 494 that exits the primary fluid outlet 440a is directed towards fluid emitted from the fluid outlet 340 as is the externally entrained fluid 490. This gives a more concentrated output from the hairdryer as the fluid is all directed towards the internally entrained fluid flowing through the inner duct 310 thus, the hairdryer will feel more powerful as the fluid jet emitted from the hairdryer is concentrated into a smaller cross sectional area. This arrangement will give relatively more externally entrained flow 490 and less internally entrained flow within the inner duct 310 than the non-inclined example described with reference to Figure 20a.

Figure 20c the primary fluid outlet 440b is directed away from the centre of the outer wall 360 of the body 30. In this example, both the first 450 and the second 452 surfaces that define the primary fluid outlet 440a are substantially parallel to each other but are inclined away from the inner duct 310. The primary fluid outlet 440b is directed towards the outer wall 360. Fluid 496 that exits the primary fluid outlet 440b is directed away from fluid emitted from the fluid outlet 340 and towards the externally entrained fluid 490. This gives a more diffuse output from the hairdryer as the fluid is all directed outwardly thus, the hairdryer will feel less powerful as the fluid jet emitted from the hairdryer is spread into a larger cross sectional area. . This arrangement will give relatively less externally entrained flow 490 and relatively more internally entrained flow along the inner duct 310 than the non-inclined example described with reference to Figure 20a.

Figure 21 shows the easy accessibility of the controlling buttons of the hairdryer 10 and the ergonomic benefit of positioning control buttons 64 (See Figure 2) on an angled surface of the body of the hairdryer. When a hairdryer is gripped normally by a hand 500, conventionally the thumb would be positioned around the handle forming a whole or partial circle with the index finger 502. In the present hairdryer 10 the thumb 504 may grip conventionally, but the thumb is also operable to change settings such as temperature and/or flow through the hairdryer by the control buttons 64 located on the side wall 350 which forms part of the fluid inlet 320 at the rear of the product. Thus without adjusting the grip, apart from perhaps moving the thumb radially from the handle 20 to the side wall 350 a user can change the settings of the hairdryer 10. The side wall 350 is preferably angled to the outer wall 360 of the body 390. This angle γ is ideally between 1 and 90° and preferably between 30 and 60°. An angle γ of 45° is most preferred.

Figure 22 shows a graph of the velocity profile through hairdryer 10. At the fluid inlet 40, fluid entering the fluid inlet 40 is at a relatively low velocity 402, as the fluid passes through the inlet silencer the velocity 404 increases as the cross sectional area within the handle 20 decreases. Also, as the fluid enters the fan unit the velocity 406 increases again due to further restriction of the fluid flow path 400 through the motor and impeller of the fan unit 70 upstream of the fan unit 70 the velocity 408 decreases through the outlet silencer as the fluid flow path becomes less restrictive again. A minimum velocity 410 is reached when the fluid passes from the handle 20 into the body 30 of the hairdryer 10. This is because the body 30 has a larger cross sectional area than the handle and acts as a plenum which fills up with fluid slowing the fluid down. Within the body the velocity 410 is similar to that at the inlet 402. When the fluid passes through the heater 80 the velocity 412 increases slightly as the heater element provides a small restriction to the flow of the fluid. As the fluid nears the primary fluid outlet 440 the cross sectional area within the body 30 reduces to an annular ring which defines the primary fluid outlet 440, the velocity within the body increases to a maximum velocity 414 at the primary fluid outlet 440.

Having the velocity decrease as the fluid moves from the fan unit 70 to the heater 80 has a number of advantages: the body 30 acts like a plenum which stabilises the flow as it moves from a circular flow 400a within the handle 20 to an annular flow 400b within the body 30 this slows the fluid down enables a more even flow through the heater 80 so velocity and turbulence are reduced; the noise produced by the hairdryer is reduced; there is more even loading around the annular ring that forms the primary fluid outlet 440.

The main reason the velocity reduces from a fan unit velocity 406 to a heater velocity 412 is that the cross section area of the fluid flow path changes from area Ai in the circular flow 400a within the handle to an cross sectional area A2 in the annular flow 400b within the body 30, this is shown schematically in Figure 22b, A2 > Ai.

Although the outer wall 200 of the handle 20 has been described as being made from a rolled sheet of metal, alternatives methods of manufacture and materials could be used; these include, but are not limited to, an extruded tube and a plastic extrusion/moulded tube or a composite tube such as carbon fibre reinforced plastic.

The invention has been described in detail with respect to a hairdryer however, it is applicable to any appliance that draws in a fluid and directs the outflow of that fluid from the appliance.

The appliance can be used with or without a heater; the action of the outflow of fluid at high velocity has a drying effect.

The fluid that flows through the appliance is generally air, but may be a different combination of gases or gas and can include additives to improve performance of the appliance or the impact the appliance has on an object the output is directed at for example, hair and the styling of that hair.

The invention is not limited to the detailed description given above. Variations will be apparent to the person skilled in the art.

Claims

1. A hairdryer comprising a primary fluid flow path extending from a primary fluid inlet to a primary fluid outlet, a fan unit for drawing primary fluid into the primary fluid flow path, a heater for heating primary fluid in the primary fluid flow path wherein primary fluid flowing through the heater has a lower velocity than primary fluid flowing through the fan unit.

2. A hairdryer according to claim 1, wherein the heater is downstream of the fan unit.

3. A hairdryer according to claim 1 or claim 2, wherein the cross sectional area of the primary fluid flow path varies along the primary fluid flow path.

4. A hairdryer according to claim 3, wherein the cross sectional area of the primary fluid flow path is greater around the heater than around the fan unit.

5. A hairdryer according to any preceding claim, comprising a handle wherein the primary fluid inlet is in the handle.

6. A hairdryer according to claim 5, comprising a body and the primary fluid outlet is in the body wherein the primary fluid flow path extends within the handle from the primary fluid inlet to the body.

7. A hairdryer according to claim 5 or 6, wherein the fan unit is located in the handle.

8. A hairdryer according to any of claims 5 to 7, wherein the handle is substantially orthogonal to the body.

9. A hairdryer according to claim 8, wherein the primary fluid flow path flows in a first direction within the handle and a second direction within the body.

10. A hairdryer according to claim 9, wherein the first direction is substantially orthogonal to the second direction.

11. A hairdryer according to any preceding claim, wherein primary fluid flowing through the primary fluid outlet has a higher velocity than primary fluid flowing through the heater.

12. A hairdryer according to any of claims 6 to 11, wherein primary fluid flowing into the primary fluid inlet has a similar velocity to primary fluid flowing through the heater.

13. A hairdryer according to claim 12, wherein the velocity of primary fluid increases from the primary fluid inlet to the fan unit.

14. A hairdryer according to claim 12 or claim 13, wherein the velocity of primary fluid decreases from the fan unit towards the body.

15. A hairdryer according to any preceding claim, comprising a fluid flow path that extends from a fluid inlet into the body to a fluid outlet from the body.

16. A hairdryer according to claim 15, wherein within the body the primary fluid flow path surrounds the fluid flow path.

17. A hairdryer according to claim 15 or 16, wherein the body comprises an inner duct which separates the primary fluid flow path and the fluid flow path.

18. A hairdryer according to claim 17, wherein the heater surrounds the inner duct.

19. A hairdryer according to claim 17 or claim 18, wherein the heater extends along the inner duct.

20. A hairdryer according to any preceding claim, wherein the fan unit comprises a high speed motor.

21. A hairdryer according to any preceding claim, comprising a handle which houses a fan unit and the handle is lined with a lining material.

22. A hairdryer according to claim 21, wherein the lining material is 4 to 6mm thick.

23. A hairdryer according to claim 22, wherein the lining material comprises at least one of an inlet silencer and an outlet silencer.

24. A hairdryer according to claim 23, wherein the outlet silencer So is up to 100mm long.

25. A hairdryer according to claim 23 or claim 24, wherein the inlet silencer Si is 10 -200mm long.

26. A hairdryer according to claim 16 when dependent on claim 6, wherein the length Lx of the body from the fluid inlet to an upstream edge of the handle and the length Lz of the body from a downstream edge of the handle to the fluid outlet at a downstream end of the body has the relationship 2Lx=Lz.

27. A hairdryer according to claim 17 when dependent on claim 6, wherein a ratio of the diameter da of the outer wall of the body and the diameter db of the inner duct is between 0.49 and 0.6 in a hairdryer having a constant diameter handle.

28. A hairdryer according to claim 27, wherein the ratio of db: da is between 0.4 and 0.9 in a hairdryer having a non constant or varying diameter handle.

29. A hairdryer according to claim 17 when dependent on claim 6, wherein a ratio between the length 12 of the body and the diameter dh of the handle is between 1.9 and 2.5 in a hairdryer having a constant diameter handle.

30. A hairdryer according claim 29, wherein the ratio of 12: dh is preferably between 1.9 and 2.5 in a hairdryer having a non constant or varying diameter handle.

31. A hairdryer according to claim 17 when dependent on claim 6, wherein the body has an outer wall and a ratio between the diameter da of the outer wall of the body and the diameter dh of the handle is between 1.6 and 3.4 in a hairdryer having a constant diameter handle

32. A hairdryer according to claim 6, wherein a ratio between the length 12 of the body and the diameter da of the body is between 1.1 and 1.6 in a hairdryer having a fan unit in the handle.

33. A hairdryer according to claim 32, wherein the ratio of 12: da is between 0.8 and 1.6 in a hairdryer having the heater in the body.

34. A hairdryer according to claim 6, wherein a ratio between the length 12 of the body and the diameter da of the body is between 1.1 and 1.6 in a hairdryer having a fan unit in the handle.

35. A hairdryer according to claim 34, wherein the ratio of 12: da is preferably between 0.8 and 1.6 in a hairdryer having the heater in the body.

36. A hairdryer according to claim 17 when dependent on claim 6, wherein a ratio relationship between the length 12 of the body and the diameter db of the inner duct is between 1.8 and 3.4.

37. A hairdryer according to claim 36, wherein the ratio of h'. da is preferably between 1 and 3.4 in a hairdryer having the heater in the body.

38. A hairdryer according to claim 17, wherein the inner duct comprises a conical part and a tubular part wherein the conical part at least partially defines a fluid inlet and the tubular part at least partially defines a fluid outlet wherein the inner duct increases in diameter from the conical part towards the fluid outlet.

39. A hairdryer according to 6, wherein the body comprises an outer wall, an inlet end and an outlet end wherein a chamfer is provided at the outlet end wherein at the chamfer the diameter of the outer wall decreases towards the centre A—A of the outer wall and wherein the chamfer is between 30° and 60°.

40. A hairdryer according to claim 6, wherein the body comprises a primary fluid outlet defined by a first surface and a second surface of the body wherein , the first surface and second surface are substantially parallel surfaces defining and outer annular limit and an inner annular limit respectively for the primary fluid outlet.

41. A hairdryer according to claim 40, wherein the body comprises an inner duct and the first surface and second surface are additionally substantially parallel with the inner duct.

42. A hairdryer according to claim 40, wherein the body comprises an inner duct and the first surface and second surface are additionally inclined towards the inner duct adjacent the primary fluid outlet.

43. A hairdryer according to claim 40, wherein the body comprises an inner duct and the first surface and second surface are additionally inclined away from the inner duct adjacent the primary fluid outlet.