Abstract:
An attachment for a hand held appliance, the attachment having a first wall, and a bung housed within the first wall wherein each of the first wall and the bung are moulded as a single unit which are subsequently joined together. One of the first wall and the bung may include a locating rib and the other of the first wall and the bung may include a locating recess and the locating rib and locating recess are adapted to cooperate together to position the bung with respect to the first wall. In addition to the locating rib and locating recess, the first wall and the bung may be secured using one or more of gluing, welding and screwing the parts together.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of United Kingdom Application No. 1500977.2, filed Jan. 21, 2015, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    This invention relates to an attachment for a handheld appliance, in particular it relates to an attachment for a hair care appliance such as a hairdryer. 
       BACKGROUND OF THE INVENTION 
       [0003]    Removable attachments for hairdryer can have a number of different uses. The usually circular flow exiting the hairdryer can be concentrated and flattened using a concentrator nozzle/attachment or it can be expanded and slowed by a diffuser. The different types of attachment dry the hair at different speeds with different flow rates enabling different styles to be created. 
         [0004]    The fluid flowing through the attachment is often heated causing the outer surface of the attachment to become uncomfortably hot to touch. It is desirable to mitigate any overheating whilst not impairing features of the hairdryer such as the thrust through the appliance and the noise produced during use. In addition it is desirable to have close control over the mitigation of any overheating so that undesirable features such as hot spots on the surface of the attachment do not occur. 
       SUMMARY OF THE INVENTION 
       [0005]    According to one aspect, the invention provides an attachment for a hand held appliance, the attachment comprising an outer wall with a first part which is generally conical in shape, and a fluid inlet into the outer wall, wherein the fluid inlet is formed from a discontinuity in the outer wall. 
         [0006]    Also provided is a hand held appliance comprising a handle and a body wherein an outer wall of the body decreases in diameter towards a front end of the body, a primary fluid flow path extending from a primary fluid inlet into the appliance to a primary fluid outlet for emitting the fluid flow from a front end of the body, a fan unit for drawing primary flow into the primary fluid inlet and an attachment, wherein the attachment comprises an outer wall formed from a first wall and a sleeve, the outer wall having a first part which is adapted at one end to connect with the appliance, wherein the first part is generally conical in shape, and the outer wall comprises a fluid inlet is formed from a discontinuity in the outer wall and wherein the outer wall of the first part of the attachment continues along substantially the same line as the body as the outer wall of the body decreases in diameter the towards the front end of the body. 
         [0007]    Preferably, the outer wall is formed from a first wall and a sleeve. Preferably, the first wall defines a fluid flow path through the attachment. In a preferred embodiment, the sleeve extends around the first wall forming a second fluid flow path from the fluid inlet in the outer wall, the second fluid flow path extending between the first wall and the sleeve. 
         [0008]    According to another aspect, the invention provides an attachment for a hand held appliance, the attachment comprises a first end and a second end, the attachment comprising a first wall extending from the first end and defining a fluid flow path through the attachment, a sleeve extending about the first wall and defining with the first wall a second fluid flow path through the attachment, the second fluid flow path comprising a fluid inlet formed between the first wall and the sleeve wherein an outer surface of the sleeve and an outer surface of the first wall are collinear. 
         [0009]    Also disclosed is a hand held appliance comprising a handle and a body wherein an outer wall of the body decreases in diameter towards a front end of the body, a primary fluid flow path extending from a primary fluid inlet into the appliance to a primary fluid outlet for emitting the fluid flow from a front end of the body, a fan unit for drawing primary flow into the primary fluid inlet and an attachment, wherein the attachment comprises a first end which is adapted to connect with the appliance and a second end, the attachment comprising a first wall extending from the first end and defining a fluid flow path through the attachment, a sleeve extending about the first wall and defining with the first wall a second fluid flow path through the attachment, the second fluid flow path comprising a fluid inlet formed between the first wall and the sleeve wherein an outer surface of the sleeve and an outer surface of the first wall are collinear and continue along substantially the same line as the body as the outer wall of the body decreases in diameter the towards the front end of the body. 
         [0010]    The outer surface of the attachment is formed from the sleeve and a part of the first wall. The fluid inlet is formed by a gap between the sleeve and the first wall. 
         [0011]    Preferably, the fluid flow path extends from a first fluid inlet into the attachment to a first fluid outlet. The fluid flow path is defined by the first wall and extends within the first wall. 
         [0012]    In a preferred embodiment, the first fluid inlet is annular. Preferably, the fluid flow path has a cross-sectional area that expands from the first fluid inlet towards the first fluid outlet. 
         [0013]    Preferably, the attachment has a second part which is generally rectangular in shape and the cross-sectional area of the first fluid flow path contracts within the second part. 
         [0014]    Preferably, the fluid inlet is formed with blended corners. Thus the edges defining the fluid inlet are not formed with sharp corners; they are rounded to encourage fluid to flow along the surfaces. 
         [0015]    According to another aspect, is an attachment for a hand held appliance, the attachment comprising a first wall wherein the first wall defines a fluid flow path through the attachment extending from an annular first fluid inlet into the attachment to a first fluid outlet, characterised in that the fluid flow path has a cross-sectional area that expands from the first fluid inlet towards the first fluid outlet. 
         [0016]    When fluid enters the attachment, the cross-sectional area of the fluid flow path increases from that of the annular first fluid inlet. This serves to slow down the flow which is advantageous as the flow direction is changed within the attachment to alter the flow profile from an annulus to the more concentrated outlet profile. By slowing the flow, the fluid is less likely to hit the walls of the attachment and more inclined to attach to the walls and follow the curves, which may reduce the generation of noise, may reduce the production of recirculation within the fluid flow path, and may produce more laminar flow. 
         [0017]    Preferably, the attachment comprises a first part and a second part and the first part extends from the first fluid inlet towards the first fluid outlet and the second part extends from the first fluid outlet towards the first fluid inlet and wherein the cross-sectional area expands within the first part. 
         [0018]    It is preferred that the first part is conical is shape. 
         [0019]    Preferably, the second part is elliptical or generally rectangular in shape. 
         [0020]    It is preferred that the annular first fluid inlet is formed from the first wall and a bung that extends within the first wall. 
         [0021]    Preferably, within the second part the fluid flow path has a cross-sectional area that at least initially contracts. Thus as fluid moves from the first part to the second part, the cross sectional area of the attachment decreases or is reduced. The attachment has a fluid flow path that starts at the first fluid inlet cross sectional area −X, increases above X within the first part of the attachment and then decreases towards X within the second part, as fluid flowing within the fluid flow path moves towards the first fluid outlet. 
         [0022]    It is preferred that the first fluid outlet has a cross-sectional area and within the second part, the cross-sectional area of the first fluid flow path contracts until it is the same as the cross-sectional area of the first fluid outlet. 
         [0023]    As the flow profile is changed within the attachment a number of things occur. The flow is slowed down during the initial expansion and turned to form the outlet profile. This expansion and slowing of the flow causes thrust to be lost. By contracting the cross-sectional area once the flow has been turned the fluid is re-concentrated which increases the thrust of fluid that exits from the first fluid outlet of the attachment. 
         [0024]    Preferably, the attachment comprises a sleeve wherein the sleeve extends over the first wall forming a fluid flow path through the attachment. 
         [0025]    It is preferred that the second fluid flow path extends from a second fluid inlet formed between the sleeve and the first wall. 
         [0026]    Also disclosed is a hair care appliance comprising a handle and a body, a primary fluid flow path extending from a primary fluid inlet into the appliance to an annular primary fluid outlet for emitting the fluid flow from a front end of the body, a fan unit for drawing primary flow into the primary fluid inlet and an attachment, the attachment comprising a first wall wherein the first wall defines a fluid flow path through the attachment extending from an annular first fluid inlet into the attachment to a first fluid outlet, wherein, in use the annular first fluid inlet is in fluid communication with the annular primary fluid outlet, characterised in that the fluid flow path has a cross-sectional area that expands from the first fluid inlet towards the first fluid outlet. 
         [0027]    Preferably, the attachment has a cross sectional area that is greater than that of the annular primary fluid outlet. 
         [0028]    A further aspect of the invention provides an attachment for a hand held appliance, the attachment having a first wall and a bung housed within the first wall wherein each of the first wall, the sleeve and the bung are moulded as a single unit which are subsequently joined together. 
         [0029]    It is preferred that one of the first wall and the bung comprises a locating rib and the other of the first wall and wherein the bung comprises a locating recess and the locating rib and locating recess are adapted to cooperate together to position the bung with respect to the first wall. 
         [0030]    Preferably, in addition to the locating rib and locating recess, the first wall and the bung are secured using one or more of gluing, welding and screwing the parts together. 
         [0031]    Preferably, the attachment comprises a fluid flow path extending between the first wall and the bung. It is preferred that the fluid flow path extends from a first fluid inlet into the attachment. Preferably, the first fluid inlet is annular. 
         [0032]    It is preferred that the attachment further comprises a sleeve extending about the first wall. 
         [0033]    Preferably, the sleeve is moulded as a single unit and is subsequently joined with the first wall. 
         [0034]    It is preferred that the first wall comprises at least one protrusion extending towards the sleeve. 
         [0035]    Preferably, the sleeve comprises at least one cooperating protrusion extending towards the first wall. 
         [0036]    It is preferred that the at least one protrusion and the at least one cooperating protrusion cooperate together when the sleeve and the first wall are assembled to provide a defined position for the sleeve with respect to the first wall. 
         [0037]    Preferably, at least one of the at least one protrusion and the at least one cooperating protrusion comprises a locating feature which locates the sleeve with respect to the first wall in the defined position. 
         [0038]    It is preferred that the attachment has a first part and a second part, wherein the first part is conical and the second part is generally elliptical. 
         [0039]    Preferably, the at least one protrusion and the at least one cooperating protrusion are located in the first part of the attachment. 
         [0040]    It is preferred that the attachment comprises a second fluid flow path extending between the first wall and the sleeve. 
         [0041]    Preferably, the second fluid flow path extends from a fluid inlet formed between the first wall and the sleeve. 
         [0042]    Also disclosed is a hand held appliance comprising an attachment according to any preceding claim. The hand held appliance is preferably a hair care appliance and more preferably a hairdryer. 
         [0043]    A further aspect of the invention provides a hair care appliance comprising a handle and a body, a primary fluid flow path extending from a primary fluid inlet into the appliance to a primary fluid outlet for emitting the fluid flow from a front end of the body, a fan unit for drawing primary flow into the primary fluid inlet and an attachment, the attachment having a first wall and a bung housed within the first wall wherein each of the first wall and the bung are moulded as a single unit which are subsequently joined together wherein the attachment comprises a fluid flow path extending between the first wall and the bung and, when the attachment is attached to the appliance, the fluid flow path is in fluid communication with the primary fluid outlet. 
         [0044]    Preferably, the primary fluid outlet is annular. 
         [0045]    Preferably, the attachment comprises a sleeve extending about the first wall and a second fluid flow path extending between the first wall and the sleeve wherein the second fluid flow path extends from a fluid inlet formed between the first wall and the sleeve. 
         [0046]    Preferably, the hair care appliance is a hairdryer. Alternatively, the hair care appliance is a hot styling appliance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0047]    The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0048]      FIG. 1  shows a hairdryer and attachment according to the invention; 
           [0049]      FIG. 2  shows a cross section through the hairdryer of  FIG. 1 ; 
           [0050]      FIG. 3  is a front isometric view of an attachment according to the invention; 
           [0051]      FIG. 4  is a rear isometric view of an attachment according to the invention; 
           [0052]      FIGS. 5 a  and 5 b    are cross sections through a top view of the attachment; 
           [0053]      FIG. 6  is a side cross section through the attachment when attached to the hairdryer; 
           [0054]      FIG. 7 a    is a simplified cross section through the attachment; 
           [0055]      FIG. 7 b    is an enlarged view of the fluid inlet into the attachment; 
           [0056]      FIG. 8 a    is a front exploded isometric view of the attachment; 
           [0057]      FIG. 8 b    is a rear exploded view of the attachment; and 
           [0058]      FIG. 9  shows a graph of variation in cross-sectional area through the first fluid flow path. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0059]      FIGS. 1 and 2  show a hairdryer  10  with a handle  20  and a body  30 . An attachment  100  is connected to the hairdryer  10  in  FIG. 1 . 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 . At a distal end of the cable  50  from the hairdryer  10  a plug (not shown) is provided, the plug may provide electrical connection to mains power or to a battery pack for example. 
         [0060]    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. The cable  50  is located approximately in the middle of the end wall  210  so extends from the centre of the handle  20 . 
         [0061]    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 body  30  has a first end  32  and a second end  34 , 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. 
         [0062]    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 inner duct  310  towards the primary fluid outlet  440  at the second end  34  of the body  30 . 
         [0063]    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 . 
         [0064]    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 inner 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 inner duct  310  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 inner duct  310 . This side wall  350  at least partially defines the fluid inlet  320 . The primary fluid outlet  440  is annular and surrounds the fluid flow path. 
         [0065]    A printed circuit board (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 inner duct  310  between the inner duct  310  and the outer wall  360 . The PCB  75  controls parameters such 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. 
         [0066]    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  FIG. 3 a   , 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. 
         [0067]    The body  30  of the hairdryer  10  decreases in diameter towards the second end  34 . This decrease in diameter has a constant gradient. The body  30  has a first part  30   a  which is generally tubular and extends from the first end  32  and a second part  30   b  which is conical and extends from a downstream end of the first part  30   a  to the second end  34 ; thus, the outer wall  360  of the body decreases in diameter towards a front end of the body. The angle δ subtended by the second part  30   a  in this example is around 30°. 
         [0068]    The attachment  100  will now be described in more detail with particular reference to  FIGS. 1 and 3 to 8   b . The attachment  100  is a concentrator nozzle which attaches to the second end  34  of the hairdryer  10 . The attachment  100  has a first part  180  and a second part  190 . The first part  180  attaches to the second end  34  of the hairdryer  10  and is conical. The second part  190  extends from the first part  180  towards a fluid outlet  140  from the attachment  100  and is generally elliptical or rectangular with rounded corners. This shape change concentrates the circular or annular flow from the hairdryer  10  to a more focused area. 
         [0069]    In this example, the attachment  100  includes a first wall  102 , a sleeve  110  and a bung  120 . Referring to  FIG. 6 , the first wall  102  engages with a front face  360   a  of the outer wall  360  of the hairdryer  10 . Magnets  370  are provided in the front face  360   a  of the outer wall  360  which engage with magnetic material  104  that extends around a mating face  106  of the first wall  102 . 
         [0070]    There are two fluid flow paths through the attachment  100 , however these do not correspond to the two fluid flow paths through the hairdryer  10 . A first fluid flow path  130  extends within the first wall  102  and is in fluid communication with the primary fluid outlet  440  of the hairdryer  10 , thus this first fluid flow path  130  can contain heated fluid. Any hot fluid will heat up the first wall  110  and the magnetic material  104  housed in the first wall  110 . The first fluid flow path  130  has a first fluid inlet  132  into the attachment  100  and a first fluid outlet  134 . 
         [0071]    A second fluid flow path  150  is formed between the first wall  102  and the sleeve  110 . The second fluid flow path  150  has a second fluid inlet  154  into the attachment  100  and extends to the fluid outlet  140  of the attachment  100 . This second fluid flow path  150  takes fluid from outside the hairdryer  10  and provides an insulating layer of fluid that takes heat from the first wall  102  to prevent the attachment  100  from getting too hot to touch if a user wishes to remove the attachment  100  from the hairdryer  10 . 
         [0072]    The sleeve  110  extends around the first wall  102  for the whole of the second part  190  of the attachment  100  and the majority of the first part  180  and is spaced from the first wall  102 . In this example, the sleeve  110  extends beyond the first wall  102  at the fluid outlet  140 . 
         [0073]    The first part  180  of the attachment  100  is conical and is formed from an outer face  108  of the first wall  102  and an outer face  112  of the sleeve  110 . Both of the outer face  108  of the first wall  102  and the outer face  112  of the sleeve  110  follow a line described by the second end  34  of the hairdryer  10 . Thus, as the body  20  of the hairdryer  10  decreases in diameter towards the second end  34 , the attachment also decreases in diameter over the first part  180 . This decrease, as with the body  30  of the hairdryer  10 , is of a constant gradient. The outer face  108  of the first wall  102  and the outer face  112  of the sleeve  110  are collinear. The angle δ subtended by the outer face  108  of the first wall  102  and the outer face  112  of the sleeve  110  in this example is around 30°. It is the same as the angle δ subtended by the second part  30   b  of the body  30  of the hairdryer  10 . 
         [0074]    The outer face  108  of the first wall  102  extends from the mating face  106  towards the fluid outlet  140  of the attachment  100 , initially matching the gradient of the second end  34  of the hairdryer  10 . After a short distance, the first wall  102  turns towards a central axis Y-Y of the attachment  100  producing a side wall  152 . This side wall  152  forms part of a second fluid inlet  154  into the attachment  100 . The side wall  152  is substantially orthogonal to the central axis Y-Y of the attachment  100  except at the junction  156  between the outer face  108  of the first wall  102  and the side wall  152  which has a blended corner with an internal angle  13  which is greater than 90°. Downstream of the side wall  152  is an inner wall  158 , this inner wall  158  is approximately parallel to the sleeve  110 , the distance d between the inner wall  158  and the sleeve is 1-3 mm and is constant along the first part  180  of the attachment  100 . 
         [0075]    The sleeve  110 , and in particular an upstream face  114  of the sleeve  110  forms the other part of the second fluid inlet  154 . This upstream face  114  is also substantially orthogonal to the central axis Y-Y of the attachment  100  apart from the junction  116  of the outer face  112  of the sleeve  110  with the upstream face  114  which has a blended corner with an internal angle α which is less than 90°. By having β&gt;α fluid that is drawn into the second fluid inlet  154  attaches to the side wall  152  which improves the heat removal from the magnetic material  104 . This is advantageous as the magnetic material tends to heat up more quickly than the surrounding attachment material which in this case is a plastic material. 
         [0076]    The distance between the side wall  152  and the upstream face  114  is approximately 1 mm. This has been found to allow sufficient flow of fluid through the second fluid flow path  150  to cool the attachment  100 . 
         [0077]    The first fluid flow path  130  extends within the first wall  102 . The first fluid flow path  130  accepts fluid from the primary fluid flow path  400  of the hairdryer  10 . As the primary fluid outlet  440  is annular, the first fluid inlet  132  is annular. The bung  120  is provided to block the fluid flow path  300  and to guide fluid exiting the primary fluid flow path  400  through the attachment  100  as the flow profile changes from annular at the first fluid inlet  132  to elliptical or generally rectangular at the first fluid outlet  134 . 
         [0078]    The bung  120  is circular at one end and this end is adapted to be inserted into the inner duct  310 . Within the first part  180  of the attachment, the bung  120  is also cone shaped then as the attachment transitions into the rectangular shape, the bung  120  flattens and narrows matching the shape change of the first wall  102 . This provides a smooth transition of the primary flow from an annular flow profile to a substantially rectangular profile. 
         [0079]    In order to provide maximum thrust at the fluid outlet  140  of the attachment  100  and to minimise pressure loss produced by the restriction formed in the attachment  100 , the cross-sectional area within the first fluid flow path  130  is non-constant. Referring now to  FIG. 9  in particular, fluid exiting the primary fluid outlet is at high velocity and it is desirable to focus this flow without losing momentum or producing noise. When the fluid exits the primary fluid outlet  440  and enters the first fluid flow path  130 , the cross-sectional area is increased  250 . This causes the fluid to slow or reduce in velocity, encourages the flow to stick to the walls and turn down the path. There is less recirculation of fluid and by slowing the flow down there are less pressure losses from non-laminar flow hitting the walls. 
         [0080]    Once the fluid has been turned around the corner produced by the bung  120  and the first wall  102 , the cross-sectional area of the first fluid flow path is reduced  260 . This corresponds approximately with the end of the bung  120 . Reducing the cross-sectional area increases the velocity of the fluid enabling maximisation of thrust from the fluid outlet  140  of the attachment  100 . 
         [0081]    Reduction of the production of noise is from the shape of the bung  120 . A first part of the bung  124  is conical and matches the profile of the first wall  102  and is the part that turns the fluid from an annular flow to a laminar flow from a substantially rectangular fluid outlet  14 . A second part of the bung  126  is downstream of the first part of the bung  124  and flattens to a line profile  128 . Two important features that reduce the production of noise are the angle of an inner face  102   a  the first wall  102  with respect to the central axis Y-Y of the attachment  100 . An angle γ of around 35° is beneficial to both thrust and acoustics. In addition the distance between the line profile  128  of the bung and the downstream end  102   b  of the first wall  102  should be 10 to 30 mm, preferably around 20 mm. Also, it has been found that the exit area of the first fluid outlet  134  impacts the thrust from the attachment  100 . For this attachment a first fluid outlet of 340-350 mm 2  has been found to maximise thrust. 
         [0082]    In addition to assisting with noise, the bung  120  flattening down with a duck billed shape to a line profile  128  produces more even flow from the outlet  140 . Often concentrator nozzles have uneven flow, with more flow at each side of the generally rectangular shape, whereas having the bung profile which smoothly transitions from conical through a duck bill to an edge provides much more even flow across the whole of the fluid outlet. 
         [0083]    Of course, the skilled person will appreciate that these figures and dimensions apply to this attachment  100  on this hairdryer  10  variations will be required for alternative schemes. 
         [0084]    Referring in particular to  FIGS. 8 a  and 8 b   , the construction of the attachment  100  will now be discussed. It is desirable to minimise connection points between each of the bung  120  with the first wall  102  and the first wall  102  with the sleeve  110  as each point or line of contact causes disturbance to flow and possibly a route for heat transfer to the sleeve  110 . In order to mitigate this, the separate parts of the attachment  100  are ultrasonically welded along welding ribs. 
         [0085]    The bung  120  comprises a slot  350  that extends along the first part  124  and the second part  126  to the line profile  128  on both sides of the bung  120 . This slot  350  is orthogonal to the flattened duck billed part of the bung  120  and the line profile  128 . The slot  350  is adapted to cooperate with and receive a “U-shaped” rib  352  extending from the inner face  102   a  of the first wall  102 . Once the rib  352  is correctly inserted into the slot  350 , the two parts are ultrasonically welded. As an alternative, the two parts are glued or screwed together. 
         [0086]    The inner wall  158  of the first wall  102  comprises two pairs of ribs  354 , one pair located on each side of the cone portion of the first wall  102 . These two pairs of ribs  354  are ideally spaced from the rib  352  and slot  350  so there is not a clear heat transfer path through the attachment  100 . A further set of two pairs of ribs  356  are located on the inner surface  120   a  of the sleeve  120 . This further set of two pairs of ribs  356  each have a locating feature  358  to ensure that the two pairs of ribs  354  of the first wall  102  are housed between the further set of two pairs of ribs  356  of the sleeve  102 . This helps to maintain concentricity of the sleeve  102  and the first wall  110  which reduces the chance of hot spots due to a variation in the distance between the sleeve  110  and the first wall  102 . The locating feature  358  defines the position of the sleeve  102  with respect to the first wall  110 . Once the various pairs of ribs are correctly aligned, the sleeve and first wall are ultrasonically welded. As an alternative, the two parts are glued or screwed together. 
         [0087]    By having the construction features only located on the first part  180  of the attachment  100 , the disruption to flow is minimised; and the risk of heat transfer is reduced. By moulding the sleeve from one part, unsightly mould lines of the more traditional two-part piece are removed. In addition, a user is more likely to hold the attachment by the second part  190  as this part is easier to grip. By restricting the construction features to being within the first part  180  there are no regions where the sleeve  102  and the first wall  110  contact within the second part  190  so there is no direct heat transfer path. 
         [0088]    The positioning of the different parts of the attachment with respect to each other is important as the sleeve  102  and the first wall  110  define a second fluid inlet  154  into the attachment and the first wall  110  together with the bung  120  define a first fluid inlet  132  into the attachment. Any non-concentricity between any of the different parts will result in uneven flow, hot spots and possibly a reduction in the life of the attachment and hairdryer to which it is attached in use. 
         [0089]    The invention has been described in detail with respect to a hairdryer and a hot styling appliance however, it is applicable to any appliance that draws in a fluid and directs the outflow of that fluid from the appliance. 
         [0090]    The appliance can be used with or without a heater; the action of the outflow of fluid at high velocity has a drying effect. 
         [0091]    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 that the output is directed at, for example, hair and the styling of that hair. 
         [0092]    The attachment has been described with a cool wall sleeve, however this sleeve is not essential to all embodiments herein described. For example, the same construction method is applicable for an attachment comprising the bung and the first wall; obviously the attachment ribs  354  are unnecessary if there is no sleeve. In addition, the concept of initially expanding the cross-sectional area of the fluid flow path as fluid enters the attachment is valid for any attachment that has a change in flow direction from the hairdryer to the attachment outlet. 
         [0093]    The attachment described has been described with respect to an amplifying hairdryer, again it will be apparent to the skilled person that this is an optional feature. The attachment described may be used with a conventional single fluid outlet hairdryer; the attachment described herein is useable with such a conventional hairdryer with or without the bung feature. Obviously the bung would not require insertion into a duct; it would require to be flush with or recessed within the end of the attachment that attaches to the conventional hairdryer. 
         [0094]    The attachment described is attached to the hairdryer using magnetic attraction. Again, this is not essential to the invention and alternative connection methods such as snap fit, friction fit and rotational securement of the attachment to the hairdryer are equally applicable. 
         [0095]    The invention is not limited to the detailed description given above. Variations will be apparent to the person skilled in the art.