Abstract:
A hairdryer including: a handle; a body comprising a duct extending within the body; a fluid flow path extending through the duct from a fluid inlet through which a fluid flow enters the hairdryer to a fluid outlet for emitting the fluid flow from a front end of the body; a primary fluid flow path extending at least partially through the body from a primary fluid inlet through which a primary fluid flow enters the hairdryer to an annular primary fluid outlet at a front end of the body; a fan unit for drawing the primary fluid flow through the primary fluid inlet; and an attachment for adjusting at least one parameter of fluid emitted from the hairdryer, the attachment being attachable to the hairdryer so that the attachment protrudes from the front end of the body, wherein the attachment is configured to inhibit the generation of the fluid flow.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/934,692, filed Jul. 3, 2013, which claims the priority of United Kingdom Application No. 1211829.5, filed Jul. 4, 2012, United Kingdom Application No. 1211830.3, filed Jul. 4, 2012, United Kingdom Application No. 1211831.1, filed Jul. 4, 2012, and United Kingdom Application No. 1211833.7, filed Jul. 4, 2012, the entire contents of each of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to an attachment for a hand held appliance, in particular an attachment for a hairdryer and an appliance, particularly a hairdryer comprising such an attachment. 
       BACKGROUND OF THE INVENTION 
       [0003]    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. 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. 
       SUMMARY OF THE INVENTION 
       [0004]    According to a first aspect, the invention provides a hairdryer comprising a handle, a body comprising a duct, a fluid flow path extending through the duct and from a fluid inlet through which a fluid flow enters the hairdryer to a fluid outlet for emitting the fluid flow from a front end of the body, a primary fluid flow path extending at least partially through the body from a primary fluid inlet through which a primary fluid flow enters the hairdryer to a primary fluid outlet, a fan unit for drawing the primary fluid flow through the primary fluid inlet, and wherein the fluid flow is drawn through the fluid flow path by fluid emitted from the primary fluid outlet, and an attachment for adjusting at least one parameter of fluid emitted from the hairdryer, the attachment being attachable to the hairdryer so that the attachment protrudes from the front end of the body. 
         [0005]    The hairdryer has a primary flow which is that processed by and drawn into the appliance by the fan unit and a fluid flow which is entrained by the primary, processed flow. Thus the fluid flow through the hairdryer is amplified by the entrained flow. 
         [0006]    Preferably, the attachment is attached to the hairdryer through insertion of part of the attachment into the duct through the fluid outlet. Preferably, said part of the attachment is slidably insertable into the duct through the fluid outlet. It is preferred that the attachment is retained within the duct by way of friction between the attachment and the duct. 
         [0007]    Preferably, the attachment is in the form of a nozzle defining a nozzle fluid flow path extending from a nozzle fluid inlet through which the primary fluid flow enters the nozzle to a nozzle fluid outlet for emitting the primary fluid flow. Preferably, the nozzle comprises a first end which is insertable into the duct, and a second end remote from the first end, and wherein the nozzle fluid inlet is located between the first end and the second end of the nozzle. It is preferred that the nozzle fluid inlet comprises at least one aperture extending at least partially about the longitudinal axis of the nozzle. The longitudinal axis extends between the first end and the second end of the nozzle. 
         [0008]    Preferably, the nozzle fluid inlet comprises a plurality of apertures extending circumferentially about the longitudinal axis of the nozzle. 
         [0009]    It is preferred that the at least one aperture has a length extending in the direction of the longitudinal axis of the nozzle, and wherein the length of said at least one aperture varies about the longitudinal axis of the nozzle. 
         [0010]    Preferably, the primary fluid outlet is configured to emit the primary fluid flow into the duct, and part of the nozzle is insertable into the duct through the fluid outlet to receive the primary fluid flow from the primary fluid outlet. 
         [0011]    It is preferred that the nozzle comprises a side wall between the first end and the second end, and wherein a portion of the side wall which is located between the first end and the second end of the nozzle at least partially defines the nozzle fluid inlet. Preferably, the side wall is tubular in shape. Preferably, the nozzle fluid inlet is formed in the side wall. It is preferred the side wall extends about an inner wall, and wherein the nozzle fluid inlet is located between the inner wall and the side wall. Preferably, the inner wall is tubular in shape. 
         [0012]    It is preferred that the side wall extends from the first end to the second end, and the nozzle comprises an outer wall extending at least partially about the side wall, and wherein the nozzle fluid inlet is located between the outer wall and the side wall. Preferably, the outer wall is tubular in shape. It is preferred that the nozzle fluid outlet is located between the walls. 
         [0013]    Preferably, the nozzle comprises a further nozzle fluid inlet through which the fluid flow enters the nozzle. Preferably, the fluid flow and the primary fluid flow combine within the nozzle fluid flow path to form a combined fluid flow which is emitted from the nozzle fluid outlet. 
         [0014]    Preferably, the nozzle comprises means for closing the further nozzle fluid inlet depending on the extent to which the nozzle has been inserted within the duct. It is preferred that the means for closing the further nozzle fluid inlet is configured to move from an open position to a closed position when the primary fluid flow enters the nozzle. 
         [0015]    Preferably, the nozzle comprises a further nozzle fluid outlet for emitting the fluid flow, and wherein within the nozzle the primary fluid flow is isolated from the fluid flow. 
         [0016]    According to a second aspect, the invention provides a hairdryer comprising a handle, a body comprising a fluid outlet and a primary fluid outlet, a fan unit for generating fluid flow through the hairdryer, the hairdryer comprising a fluid flow path extending from a fluid inlet through which a fluid flow enters the hairdryer to the fluid outlet, and a primary fluid flow path extending from a primary fluid inlet to the primary fluid outlet, a heater for heating a primary fluid flow drawn through the primary fluid inlet, and a nozzle attachable to the body, the nozzle comprising a primary nozzle fluid inlet for receiving the primary fluid flow from the primary fluid outlet, and a primary nozzle fluid outlet for emitting the primary fluid flow, a further nozzle fluid inlet for receiving the fluid flow from the fluid outlet, a further nozzle fluid outlet for emitting the fluid flow, and wherein within the nozzle the fluid flow is isolated from the primary fluid flow. 
         [0017]    It is preferred that one of the nozzle fluid outlet and the further nozzle fluid outlet extends about the other of the nozzle fluid outlet and the further nozzle fluid outlet. Preferably, the nozzle fluid outlet and the further nozzle fluid outlet are located on opposing sides of the nozzle. It is preferred that the nozzle fluid outlet and the further nozzle fluid outlet are substantially coplanar. 
         [0018]    It is preferred that the nozzle comprises a further fluid flow path for conveying the fluid flow to the further fluid outlet, and wherein the primary fluid inlet extends at least partially about the further fluid flow path. Preferably, the primary fluid inlet surrounds the further fluid flow path. 
         [0019]    It is preferred that the nozzle comprises a first end and a second end remote from the first end, and wherein the second end of the nozzle comprises at least the further nozzle fluid outlet. Preferably, the second end of the nozzle comprises the primary nozzle fluid outlet. It is preferred that the primary nozzle fluid outlet is located between the first end and the second end of the nozzle. Preferably, the second end of the nozzle is deformable. It is preferred that the first end of the nozzle comprises the further nozzle fluid inlet. Preferably, the first end of the nozzle is insertable into the fluid flow path through the fluid outlet. It is preferred that the first end of the nozzle is slidably insertable into the fluid flow path through the fluid outlet. Preferably, the nozzle is retained within the duct by way of friction between the nozzle and the body. 
         [0020]    It is preferred that the primary fluid outlet is configured to emit the primary fluid flow into the primary nozzle fluid flow path, and wherein the primary nozzle fluid inlet is located between the first end and the second end of the nozzle. 
         [0021]    Preferably, the nozzle comprises a side wall between the first end and the second end, and wherein a portion of the side wall which is located between the first end and the second end of the nozzle at least partially defines the primary nozzle fluid inlet. It is preferred that the side wall is tubular in shape. Preferably, the side wall extends about an inner wall, and wherein the primary nozzle fluid inlet is located between the inner wall and the side wall. It is preferred that the inner wall is tubular in shape. 
         [0022]    Preferably, the side wall extends from the first end to the second end, and the nozzle comprises an outer wall extending at least partially about the side wall, and wherein the primary nozzle fluid inlet is located between the outer wall and the side wall. It is preferred that the outer wall is tubular in shape. 
         [0023]    According to a third aspect the invention provides a nozzle for a hairdryer comprising a handle, a body comprising a fluid outlet and a primary fluid outlet, a fan unit for generating fluid flow through the hairdryer, a fluid flow path extending from a fluid inlet through which a fluid flow enters the hairdryer to the fluid outlet, and a primary fluid flow path extending from a primary fluid inlet to the primary fluid outlet, and a heater for heating a primary fluid flow drawn through the primary fluid inlet, wherein the nozzle is attachable to the body, the nozzle comprising a primary nozzle fluid inlet for receiving the primary fluid flow from the primary fluid outlet, and a primary nozzle fluid outlet for emitting the primary fluid flow, a further nozzle fluid inlet for receiving the fluid flow from the fluid outlet, a further nozzle fluid outlet for emitting the first fluid flow, a primary nozzle fluid inlet for receiving the primary fluid flow from the primary fluid outlet, and a primary nozzle fluid outlet for emitting the primary fluid flow, and wherein within the nozzle the fluid flow is isolated from the primary fluid flow. 
         [0024]    Preferably, one of the further nozzle fluid outlet and the primary nozzle fluid outlet extends about the other of the further nozzle fluid outlet and the primary nozzle fluid outlet. It is preferred that the further nozzle fluid outlet and the primary nozzle fluid outlet are located on opposing sides of the nozzle. Preferably, the further nozzle fluid outlet and the primary nozzle fluid outlet are substantially coplanar. 
         [0025]    It is preferred that the nozzle comprises a further fluid flow path for conveying the further fluid flow to the further fluid outlet, and wherein the primary fluid inlet extends at least partially about the further fluid flow path. Preferably, the primary fluid inlet surrounds the further fluid flow path. 
         [0026]    It is preferred that the nozzle comprises a first end and a second end remote from the first end, and wherein the second end of the nozzle comprises at least the further nozzle fluid outlet. Preferably, the second end of the nozzle comprises the primary nozzle fluid outlet. It is preferred that the primary nozzle fluid outlet is located between the first end and the second end of the nozzle. Preferably, the second end of the nozzle is deformable. It is preferred that the first end of the nozzle comprises the further nozzle fluid inlet. Preferably, the primary nozzle fluid inlet is located between the first end and the second end of the nozzle. 
         [0027]    It is preferred that the nozzle comprises a side wall between the first end and the second end, and wherein a portion of the side wall which is located between the first end and the second end of the nozzle at least partially defines the primary nozzle fluid inlet. Preferably, the side wall is tubular in shape. It is preferred that the side wall extends about an inner wall, and wherein the primary nozzle fluid inlet is located between the inner wall and the side wall. Preferably, the inner wall is tubular in shape. 
         [0028]    It is preferred that the side wall extends from the first end to the second end, and the nozzle comprises an outer wall extending at least partially about the side wall, and wherein the primary nozzle fluid inlet is located between the outer wall and the side wall. Preferably, the outer wall is tubular in shape. 
         [0029]    Preferably, the shape of the nozzle fluid outlet is adjustable. 
         [0030]    Preferably, the attachment is configured to inhibit the emission of the fluid flow from the hairdryer. Alternatively, the attachment is configured to inhibit the generation of the fluid flow. Preferably, the attachment comprises means for inhibiting the flow of fluid along the fluid flow path to the fluid outlet. 
         [0031]    It is preferred that the means for inhibiting the flow of fluid along the flow path to the fluid outlet comprises a barrier which is located within the duct when the attachment is attached to the hairdryer. Preferably, the barrier is located at the first end of the nozzle. It is preferred that the barrier is substantially orthogonal to the longitudinal axis of the nozzle. Alternatively, the barrier is inclined to the longitudinal axis of the nozzle. 
         [0032]    Preferably, said at least one parameter of the fluid flow emitted from the hairdryer comprises at least one of the shape, profile, orientation, direction, flow rate and velocity of the fluid flow emitted from the hairdryer. 
         [0033]    According to a fourth aspect, the invention provides a hairdryer comprising a handle, a body comprising a fluid outlet, the fluid outlet comprising at least one aperture, a fan unit for generating a fluid flow from a fluid inlet through which the fluid flow enters the hairdryer to the fluid outlet, means for occluding at least part of the fluid outlet, the occluding means being moveable relative to the fluid outlet, and means for receiving an attachment for varying the shape of a fluid flow emitted from the hairdryer, wherein the attachment comprises means for engaging the occluding means as the attachment is received by the receiving means to effect movement of the occluding means relative to the fluid outlet. 
         [0034]    Preferably, the engaging means is arranged to move the occluding means away from said at least part of the fluid outlet as the attachment is received by the receiving means. 
         [0035]    It is preferred that the occluding means is arranged to move in a direction parallel to a plane in which said at least part of the fluid outlet is located. Preferably, the occluding means is slidably moveable in said direction relative to said at least part of the fluid outlet. Alternatively, the occluding means is arranged to move in a direction substantially orthogonal to a plane in which said at least part of the fluid outlet is located. 
         [0036]    It is preferred that the engaging means is arranged to move the occluding means from a first position to a second position as the attachment is received by the receiving means. Preferably, the fluid outlet comprises a first aperture and a second aperture, and wherein in the first position the occluding means is arranged to occlude only the second aperture. It is preferred that the first aperture is spaced from the second aperture. 
         [0037]    Preferably, the first aperture is located in a first plane and the second aperture is located in a second plane which is angled relative to the first plane. It is preferred that the second plane is orthogonal to the first plane. Preferably, the second aperture is located at an end of the hairdryer. 
         [0038]    In one embodiment, the fluid outlet comprises an aperture which is partially occluded when the occluding means is in the first position, and wherein the engaging means is arranged to move the occluding means away from said aperture as the attachment is received by the receiving means. It is preferred that wherein the occluding means is biased towards the first position. 
         [0039]    Preferably, the engaging means extends about part of the attachment. It is preferred that the attachment comprises a side wall, and wherein the engaging means extends about the wall. Preferably, the engaging means surrounds the side wall. It is preferred that the side wall is tubular in shape, and the engaging means comprises a lip upstanding from the side wall. 
         [0040]    Preferably, the hairdryer includes a bore extending through the body, and wherein said at least part of the fluid outlet is arranged to emit fluid into the bore. 
         [0041]    It is preferred that said at least part of the fluid outlet is annular in shape. 
         [0042]    According to a fifth aspect the invention provides a hairdryer comprising a handle, a body comprising a duct, a fan unit for generating a fluid flow from a fluid inlet through which the fluid flow enters the hairdryer to an end of the duct for emitting the fluid flow from the body, and an attachment partially insertable into the end of the duct and which at least partially defines at least one aperture for emitting the fluid flow when the attachment is located in the duct, and wherein the attachment has an external surface located downstream from said at least one aperture and over which fluid emitted from said at least one aperture is directed. 
         [0043]    Preferably, the external surface of the attachment at least partially defines said at least one aperture. It is preferred that the external surface of the attachment is convex in shape. Preferably, the external surface of the attachment comprises a Coanda surface. It is preferred that a front portion of the external surface of the attachment tapers towards a longitudinal axis of the nozzle. Preferably, the front portion of the external surface of the attachment tapers to a point. 
         [0044]    It is preferred that the attachment comprises a collar at least partially surrounding the external surface, and wherein the internal surface of the collar and the external surface define an external fluid flow path through which fluid from outside the hairdryer is drawn by fluid emitted from said at least one aperture. Preferably, said at least one aperture is located between the internal surface of the duct and the external surface of the attachment. 
         [0045]    It is preferred that the body comprises a fluid outlet for emitting the fluid flow into the duct, and wherein the attachment comprises a fluid inlet for receiving the fluid flow from the fluid outlet, and a fluid flow path extending from the fluid inlet to said at least one aperture. 
         [0046]    Preferably, the attachment comprises a first end which is insertable within the duct, and a second end remote from the first end, and wherein the fluid inlet is located between the first end and the second end of the attachment. 
         [0047]    It is preferred that the fluid inlet comprises at least one aperture extending at least partially about the longitudinal axis of the attachment. 
         [0048]    Preferably, the attachment comprises a side wall between the first end and the second end of the attachment, and wherein a portion of the side wall which is located between the first end and the second end of the attachment at least partially defines the fluid inlet. It is preferred that the side wall is tubular in shape. 
         [0049]    Preferably, the attachment comprises an outer wall extending about an inner wall which at least partially defines the fluid flow path. It is preferred that the inner wall is tubular in shape. It is preferred that the external surface of the attachment extends about the inner wall. Preferably, the inner wall is open at each end, and wherein a fluid flow is drawn through the duct and the inner wall by the fluid flow emitted from said at least one aperture. 
         [0050]    In one embodiment, the attachment comprises a first side wall extending from the first end to the second end, and a second side wall extending at least partially about the first side wall, and wherein the fluid flow path is located between the side walls. Preferably, each of the first and second side walls is tubular in shape. It is preferred that the external surface of the attachment extends about the first side wall. Preferably, the first side wall is open at each end, and wherein a fluid flow is drawn through the duct and the first side wall by the fluid flow emitted from said at least one aperture. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0051]    The invention will now be described by way of example and with reference to the accompanying drawings, of which: 
           [0052]      FIGS. 1 a  to 1 f    show various representations of a single flow path nozzle according to the invention; 
           [0053]      FIGS. 2 a  to 2 c    show various representations of a single flow path nozzle attached to a hairdryer; 
           [0054]      FIGS. 3 a  to 3 g    show various representations of a double flow path nozzle according to the invention; 
           [0055]      FIGS. 4 a  to 4 c    show a double flow path nozzle attached to a hairdryer; 
           [0056]      FIGS. 5 a  to 5 f    show a laminar flow nozzle; 
           [0057]      FIGS. 6 a  to 6 d    show a nozzle with an end valve; 
           [0058]      FIGS. 7 a  to 7 f    show a further double flow path nozzle; 
           [0059]      FIGS. 7 g  to 7 j    show the further double flow path nozzle attached to a hairdryer; 
           [0060]      FIG. 8 a    shows an alternate single flow path nozzle attached to a hairdryer; 
           [0061]      FIGS. 8 b  to 8 g    show an alternate single flow path nozzle; 
           [0062]      FIG. 9 a    shows an alternate double flow path nozzle; 
           [0063]      FIGS. 9 b  to 9 g    show an alternate double flow path nozzle; 
           [0064]      FIGS. 10 a  to 10 e    show a further single flow path nozzle; 
           [0065]      FIGS. 11 a  to 11 c    show another single flow path nozzle; 
           [0066]      FIGS. 11 d  to 11 f    show the another single flow path nozzle with a hairdryer; 
           [0067]      FIGS. 12 a  to 12 c    show a nozzle and hairdryer having two inlets into a single flow path; 
           [0068]      FIGS. 13 a  to 13 d    show an alternate two outlet arrangement; 
           [0069]      FIGS. 14 a  to 14 d    show a further nozzle and hairdryer combination; 
           [0070]      FIGS. 15 a  to 15 d    show an alternative nozzle with a hairdryer; 
           [0071]      FIGS. 16 a  to 16 g    show yet another single flow path nozzle and hairdryer; 
           [0072]      FIGS. 16 h  and 16 i    show the hairdryer without a nozzle; 
           [0073]      FIGS. 16 j  to 16 m    show a further attachment with a hairdryer; 
           [0074]      FIGS. 17 a  to 17 c    show a single flow path nozzle attached to a hairdryer; and 
           [0075]      FIGS. 18 a  to 18 e    show a double flow path nozzle attached to a hairdryer. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0076]      FIGS. 1 a  to 1 f    show a nozzle  100  comprising a generally tubular body  110  with a longitudinal axis A-A extending along the length of the body, having a fluid inlet  120  through a wall  112  of the body  110  and a fluid outlet  130  downstream of the fluid inlet  120 . The fluid inlet  120  has a length that extends in the direction of the longitudinal axis A-A of the nozzle and is located between a first or upstream end  100   a  and a second or downstream end  100   b  of the nozzle  100 . 
         [0077]    In this example, the fluid outlet  130  is slot shaped and the length of the slot B-B is greater than the diameter C-C of the body  110 . In this example, the fluid inlet  120  comprises a number of discrete apertures  120   a  separated by reinforcing struts  120   b . The apertures  120   a  extend circumferentially about the longitudinal axis of the nozzle  100 . 
         [0078]    In use, fluid flows into the fluid inlet  120  along the length of the body  110  along fluid flow path  160  and out through the fluid outlet  130 . The upstream end  100   a  of the nozzle  100  is closed by an end wall  140  thus fluid can only enter the nozzle  100  via the fluid inlet  120  when in use. 
         [0079]      FIGS. 2 a  to 2 c    show the nozzle  100  attached to a hairdryer  200 . The nozzle  100  is inserted into the downstream end  200   b  of the hairdryer until a stop  210  is reached. In this position, the fluid inlet  120  of the nozzle  100  is in fluid communication with a primary fluid outlet  230  of the hairdryer  200 . The nozzle is an attachment for adjusting at least one parameter of the fluid flow emitted from the hairdryer and the downstream end  100   b  of the nozzle protrudes from the downstream end  200   b  of the hairdryer  200 . 
         [0080]    The hairdryer  200  has a handle  204 ,  206  and a body  202  which comprises a duct  282 ,  284 . A primary fluid flow path  260  starts at a primary inlet  220  which in this example is located at the upstream end  200   a  of the hairdryer i.e. at the distal end of the hairdryer from the fluid outlet  200   b . Fluid is drawn into the primary fluid inlet  220  by a fan unit  250 , fluid flows along primary fluid flow path  260  located on the inside of the outer body  202  of the hairdryer between the outer body  202  and the duct  282 , along a first handle portion  204  to the fan unit  250 . 
         [0081]    The fan unit  250  includes a fan and a motor. The fluid is drawn through the fan unit  250 , along a second handle portion  206  and returns to the body  202  of the hairdryer in an inner tier  260   a  of the body. The inner tier  260   a  of the body  202  is nested within the primary fluid flow path  260  between the primary fluid flow path  260  and the duct  282  and includes a heater  208 . The heater  208  is annular and heats the fluid that flows through the inner tier  260   a  directly. Downstream of the heater  208 , fluid exits the primary fluid flow path at the primary outlet  230 . 
         [0082]    With the nozzle  100  attached to the hairdryer  200 , the primary outlet  230  is in fluid communication with the fluid inlet  120  of the nozzle  100 . Fluid that flows out of the primary outlet  230  flows along the body  110  of the nozzle  100  to the nozzle outlet  130 . 
         [0083]    The hairdryer  200  has a second fluid flow path  280 . This second fluid flow path  280  flows from a second inlet  270  along the length of the body  202  of the hairdryer through duct  282  to a second outlet  290  outlet where, when there is no nozzle attached to the hairdryer, fluid flowing through the second fluid flow path  280  mixes with the primary fluid at the primary fluid outlet  230 . This mixed flow continues along duct  284  to the fluid outlet  200   b  of the hairdryer. The fluid that flows through the second fluid flow path  280  is not processed by the fan unit  250 ; it is entrained by the primary fluid flow through the primary fluid flow path  260  when the fan unit is switched on. 
         [0084]    The second fluid flow path  280  can be considered to flow along a tube defined by an upstream duct  282  and a downstream duct  284  where the primary outlet  230  is an aperture in the tube between the ducts  282  and  284 . The nozzle is partially inserted into the tube defined by the ducts  284 ,  282 . In this example the nozzle  100  is slidably inserted into hairdryer outlet  200   b  along downstream duct  284  past the aperture or primary fluid outlet  230  into the upstream duct  282 . The nozzle  100  is retained in the duct  282 ,  284  by friction. In this example, the friction is provided between stop  210  and the duct  284  of the hairdryer. 
         [0085]    Nozzle  100  is a single flow path nozzle and only fluid that has been processed by the fan unit  250  from the primary fluid flow path  260  flows through the nozzle  100 . The end wall  140  of the nozzle  100  is a barrier that blocks the second fluid flow path  280  and thereby prevents entrainment into the second fluid flow path when the nozzle is properly attached to the hairdryer. The nozzle  100  prevents emission of the entrained fluid and inhibits the generation of the entrained fluid. 
         [0086]    As an alternative, the nozzle could extend into downstream duct  284  of the hairdryer  200  but not as far as the primary fluid outlet  230 . In this example, fluid from the primary fluid flow path  260  would mix with entrained fluid from the second fluid flow path  280  at the primary fluid outlet  230  and the mixed flow would enter the nozzle at the upstream end of the nozzle and continue to the fluid outlet  130  of the nozzle producing a combined fluid flow at the nozzle outlet. 
         [0087]    It is advantageous that the end wall  140  of the nozzle  100  comprises a valve. This assists if the nozzle  100  is inserted into the hairdryer whilst the hairdryer is switch on. The valve is designed to open and let the full fluid flow through it this is for example around 22 l/s. Referring now to  FIGS. 6 a  to 6 d   , the operation of a valve in the nozzle will now be described. When the nozzle  100  is initially inserted into the outlet end  200   b  of a hairdryer  200  as is shown in  FIG. 6 a   , the valve  150  in the upstream end wall  140  of the nozzle  100  opens. The valve  150  is attached to a central strut  152  of the end wall  140  and when the force of the fluid flow is high enough the valve  150  folds into the nozzle  100  to make an opening  154 , for example an annular opening, in the end wall  140  of the nozzle  100 . The valve  150  is pushed downstream by the force of the fluid flowing into the nozzle  100 . 
         [0088]    Once the inlet  120  is partially aligned with the primary outlet  230  of the hairdryer  200 , some of the primary flow will flow through the inlet  120  which results in a reduction in the pressure at the valve  150 . Once at least the majority of the primary flow goes through the inlet  120 , the valve  150  will shut as is shown in  FIG. 6 c   . When the valve  150  is shut the end wall  140  of the nozzle is blocked so fluid cannot flow through the second fluid flow path  280 . Thus the only flow is from the primary outlet  230  of primary fluid flow path  260  into the inlet  120  of the nozzle. 
         [0089]    Nozzle  100  is a hot styling nozzle. Although around only half of the normal flow through the hairdryer will flow through the nozzle to the outlet  130  the velocity of the flow is increased by the shape of the nozzle so a user will feel a similar force to that of normal flow. Normal flow is the total flow through the hairdryer without an attachment i.e. the primary flow plus the second or entrained flow. The shape of the nozzle outlet  130  reduces the cross sectional area compared with the hairdryer outlet  200   b  which increases the velocity of the flow. 
         [0090]    Whilst the hairdryer shown has the primary fluid flow path flowing through the handles of the hairdryer, this is not required. The primary fluid flow path can alternatively flow from the primary inlet  220  along the body  202  through the heater to the primary fluid outlet  230  and thence into the nozzle. 
         [0091]      FIGS. 11 a  to 11 f    show a nozzle  800  and a nozzle  800  attached to a hairdryer  200 . In this embodiment, components illustrated and described with respect to  FIGS. 2 a  to 2 c    have like reference numbers. The nozzle is similar to nozzle  100  but instead of a valve  150 , this nozzle  800  is provided with a slanted upstream end  800   a  and fluid inlet  820  i.e. the fluid inlet  820  has a length that extends in the direction of the longitudinal axis of the nozzle  800  and varies about the longitudinal axis of the nozzle. The fluid inlet  820  is defined by a side wall  822  of the body  810  of the nozzle  800  where the side wall  822  is substantially orthogonal to the wall  812  of the body and the longitudinal axis A-A of the nozzle  800 . 
         [0092]    When the nozzle  800  is inserted into the outlet end  200   b  of a hairdryer  200 , the fluid inlet  820  gradually aligns with the primary fluid outlet  230  of the hairdryer ( FIG. 11 f   ). When the nozzle  800  is fully inserted as is shown in  FIG. 11 d   , the whole of the annular primary fluid outlet  230  is in fluid communication with the nozzle inlet  820 . 
         [0093]    There will be an initial resistance to the insertion of the nozzle  800  when the hairdryer is switched on as there will be both primary and second fluid flowing through the hairdryer however, the entrainment effect will gradually reduce as the hairdryer outlet end  200   b  is blocked by the slanted nozzle inlet end  800   a  until the hairdryer outlet end  800   b  is completely blocked. At this point, primary flow from the primary fluid outlet  230  that cannot enter the fluid inlet  820  is redirected down a second fluid flow path  280  towards the rear or upstream end  200   a  of the hairdryer. So, when the nozzle is initially inserted the primary flow cannot exit the downstream end  800   b  of the nozzle but can flow in a reverse direction along the second fluid flow path  280 . This feature provides protection from the heater overheating during the nozzle insertion process as there will always be some fluid flowing through the primary fluid flow path. 
         [0094]      FIGS. 3 a  to 3 f    show a double flow path nozzle  300  comprising a generally tubular body  310  having an outer wall  312  and an inner wall  382 . The outer wall  312  extends from an upstream end  300   a  to a downstream end  300   b  of the nozzle  300  and about the inner wall  382 . The outer wall  312  has an aperture which forms a fluid inlet  320  and a fluid outlet  330  is provided downstream of the fluid inlet  320 . In use, fluid flows into the fluid inlet  320  along the length of the body  310  along fluid flow path  360  provided between the outer wall  312  and the inner wall  382  and out through the fluid outlet  330 . The inner wall  382  is generally tubular however, at the fluid inlet  320  it curves outwards  322  and joins the outer wall  312  forming an upstream end to the fluid inlet  320 . 
         [0095]    A further inlet  370  is provided in the upstream end  300   a  of the nozzle  300  and fluid flows along a further fluid flow path  380  to further fluid outlet  390 . The further fluid flow path  380  flows within a tube defined by the inner wall  382 . The further fluid flow path  380  is nested within the fluid flow path  360  and surrounded by the fluid flow path  360 . The fluid outlet  330  and further fluid outlet  390  have substantially the same shape and configuration and in this example, comprise a rounded slot with a central wider region. This means that fluid flow is directed mainly in the central region but that the drying area is increased by the slot portion. 
         [0096]    The fluid outlet  330  and the further fluid outlet  390  can comprise alternative shapes such as a simple double slot  330   a ,  390   a  as is shown in  FIG. 3   g.    
         [0097]    In use, when the nozzle is attached to a hairdryer the fluid inlet is in fluid communication with a primary fluid outlet of the hairdryer and the further fluid inlet is in fluid communication with a second fluid outlet of the hairdryer. Having two fluid flow paths is advantageous as it enables manipulation of the fluid outflow to create different styling conditions depending on user requirements. 
         [0098]      FIGS. 4 a  to 4 c    show the nozzle  300  attached to a hairdryer  200 . In this embodiment, components illustrated and described with respect to  FIGS. 2 a  to 3 f    have like reference numbers. As previously described, a primary fluid flow path  260 ,  260   a  has a primary inlet  220  at an upstream  220   a  end of the hairdryer  200 , continues along the length of the body  202  of the hairdryer, down a first handle  204 , through the fan unit  250 , up a second handle  206 , back into the body  202  in an inner tier  260   a  through the heater  208  and to the primary outlet  230 . 
         [0099]    A second fluid flow path  280  is also provided and travels straight through the body  202  of the hairdryer  200  from a second inlet  270  to a second outlet  290 . With the double flow path nozzle  300  attached to the outlet end  200   b  of the hairdryer  200 , both the primary and second fluids flow from their respective inlet  220 ,  270  to a nozzle outlet  330 ,  390 . 
         [0100]    When nozzle  300  is attached to the hairdryer  200 , fluid that flows through the primary fluid flow path  260  flows to the primary outlet  230  enters the inlet  320  of the nozzle  300 , flows along the fluid flow path  360  between the outer wall  312  and the inner wall  382  to an outlet  330  of the nozzle  300  and appliance. Fluid that flows through the second fluid flow path  280  flows towards the second outlet  290 , enters the further inlet  370  of the nozzle  300  and flows along further fluid flow path  380  within the inner wall  382  to the further outlet  390  of the nozzle  300 . 
         [0101]    In this embodiment, the further flow path  380  is central to and concentric with the fluid flow path  360  i.e. the fluid flow path extends about the further fluid flow path. The further outlet  390  is surrounded by the outlet  330  and this results in a central cool fluid path with an outer perimeter of hot fluid exiting the nozzle. In order that the integrity of the hot and cold fluid flow paths are maintained and that they are isolated within the hairdryer and nozzle, the inserted nozzle  300  must seal the primary fluid outlet  330  to prevent mixing of the hot and cold flows. In this example, the outer wall  312  is provided with an upstanding collar  312   a  that extends about the outer wall  312  and seals the duct  282  thus preventing ingress of fluid from the second fluid flow path  280  into the nozzle inlet  320  and egress from the primary fluid outlet  230  into the second fluid flow path  280 . The collar  312   a  of outer wall  312  provides the friction between the nozzle and the hairdryer that retains the nozzle within the hairdryer. 
         [0102]    A second collar  312   b  is provided downstream of the fluid inlet  320  and this seals the nozzle with respect to hairdryer duct  284  and the hairdryer outlet  200   b  that surrounds the nozzle outlet  330 . This is to stop leakage around the nozzle and to provide a more focused outflow from the nozzle. 
         [0103]      FIGS. 5 a  to 5 f    show various representations of a laminar nozzle according to the invention. A nozzle  400  has a body  410  with a generally tubular outer wall  412 , and an inner wall  424  which divides the body  410  substantially in half lengthways. The outer wall  412  has an inlet  420  through the wall  412  and an outlet  430  downstream of the inlet and connected to the inlet  420  by a fluid flow path  460 . The inlet  420  is a single semicircular aperture in the outer wall  412  and is defined by the outer wall  412 , a side wall  422  and the inner wall  424 . The inlet  420  is located between a downstream end  400   b  and an upstream end  400   a  of the nozzle  400 . The side wall  422  connects between the outer wall  410  and the inner wall  424  and together with the outer wall  412  and the inner wall  424  defines the fluid flow path  460 . 
         [0104]    A further inlet  470  is provided in the upstream end  400   a  of the nozzle  400 . In this example the further inlet  470  is substantially circular to provide a fluid connection with substantially circular hairdryer ducting  284  (for example at the second fluid outlet  290  of  FIG. 2 c   ). The further inlet  470  is in fluid communication with a further outlet  490  via a further fluid flow path  480 . 
         [0105]    In order to create a laminar flow out of the nozzle  400 , the two outlets  430 ,  490  of the nozzle are situated one on top of the other or side by side depending on the orientation of the nozzle i.e. they are coplanar and located on opposing sides of the nozzle. The fluid flow path  460  and further fluid flow path  480  are also bilateral along the length of the nozzle from the inlet  420 . Upstream of inlet  420 , where there is only the further fluid flow path  480 , the further fluid flow path  480  extends from a semicircular cross-section to a circular cross-section at the further inlet  470 . This change in shape is facilitated by the side wall  422  that forms part of the fluid inlet  420 . 
         [0106]    As the nozzle  400  provides fluid communication with an annular primary flow, the diameter of the further fluid flow path  480  at the fluid inlet  420  is reduced slightly enabling fluid that exits the primary outlet of the hairdryer radially spaced  420   a  away from the inlet  420  to flow around the circumference of the nozzle and into the inlet  420 . Without this feature, flow from the primary outlet would be restricted at the inlet. 
         [0107]    In addition, a collar  412   a  is provided around the outer wall  412  at or near the upstream end of the fluid inlet  420  to seal the nozzle  400  against internal ducting  284  of a hairdryer to prevent any primary flow from a hairdryer mixing with entrained flow. 
         [0108]      FIGS. 7 a  to 7 j    show a further double flow path nozzle  500  and the nozzle attached to a hairdryer  200 . In this nozzle  500 , the relative positions of the inlets and outlets are reversed producing an inside out nozzle. 
         [0109]    The nozzle  500  has a generally tubular body  510  having a fluid inlet  520  through an outer wall  512  of the body  510  and a fluid outlet  530  downstream of the fluid inlet  520 . In use, fluid flows into the fluid inlet  520  along the length of the body  510  along fluid flow path  560  and out through the fluid outlet  530 . A further inlet  570  is provided in the upstream end  500   a  of the nozzle  500  and fluid flows from this further inlet  570  along a further fluid flow path  580  to a further fluid outlet  590 . 
         [0110]    Referring now to  FIGS. 7 g  to 7 j   , when the nozzle  500  is inserted into a hairdryer  200 , the inlet  520  aligns with a primary fluid outlet  230  of the hairdryer. Thus, fluid flows in the hairdryer from the primary fluid inlet  220 , through the primary flow path  260  past the fan unit  250  and heater  208  to a primary fluid outlet  230  then into the fluid inlet  520  of the nozzle  500  along fluid flow path  560  to fluid outlet  530 . 
         [0111]    The further inlet  570  of the nozzle  500  aligns with and is inserted into a second fluid outlet  290  of the hairdryer  200 . Fluid that is drawn into the hairdryer along a second fluid flow path  280  by the action of the fan unit  250  on the primary fluid flow path  260  enters the hairdryer at a second fluid inlet  270 , flows along a second fluid flow path  280  towards a second fluid outlet  290 . The fluid in the second fluid flow path  280  enters the further nozzle inlet  570 , flows along a further fluid flow path  580  to a further fluid outlet  590 . 
         [0112]    The fluid outlet  530  and further fluid outlet  590  are arranged so that the fluid from the primary fluid flow path  260  i.e. the fluid that has been processed by the fan unit  250  and heater by the heater  208  is surrounded by fluid from the second fluid flow path i.e. cool entrained fluid. Thus, the further outlet  590  surrounds the outlet  530  and this results in a central hot fluid path with an outer perimeter of cool fluid exiting the nozzle. In this example, the outlets  530 ,  590  of the nozzle  500  are slot shaped but they could be circular. 
         [0113]    In order to achieve this, the further inlet  570  has a circular opening to match shape and size of the second fluid outlet  290 , the further fluid flow path  580  is initially a pair of slots or a V-shaped channel  580   a  ( FIGS. 7 b , 7 d , and 7 f    in particular) formed from the outer wall  512  of the nozzle  500  and an inner wall  524  that divides the two fluid flow paths  560 ,  580  within the nozzle  500 . Downstream of the fluid inlet  520 , the inner wall  524  becomes circular and generally concentric to the outer wall  512  and the further fluid flow path  580  becomes annular in shape to form the radially outer outlet  590  of the nozzle  500  i.e. the further outlet  590  surrounds the fluid outlet  530 . 
         [0114]    Inlet  520  is annular and has a mouth  520   a  formed between the inner wall  524  and the outer wall  512  of the nozzle. The mouth  520   a  provides an entrance to the fluid flow path  560  which is generally circular within the body  510  of the nozzle  500  and surrounded by the further fluid flow path  580  downstream of the inlet  520 . 
         [0115]      FIGS. 8 a  to 8 g    show an alternate single flow path nozzle  600  having a generally tubular body  610 , a first or upstream end  600   a  and a second or downstream end  600   b . There is a fluid inlet  620  in an outer wall  612  of the body  610  between the first end  600   a  and the second end  600   b  of the nozzle  600  and a fluid outlet  630  downstream of the fluid inlet  620 . In this example, the fluid outlet  630  is ring shaped or annular and is formed by an inner wall  614  of the nozzle  600  and the outer wall  612 . 
         [0116]    The fluid inlet  620  is an opening in the outer wall  612  of the nozzle and is defined by an aperture formed from a slanted edge  622   b  of the outer wall and a curved side wall  622  provided at the upstream end of the fluid inlet which connects the outer wall  612  and the inner wall  614 . The slanted edge of the outer wall is slanted in the direction of fluid flow to reduce turbulence and pressure losses as the primary flow enters the nozzle. 
         [0117]    The outer wall  612  surrounds inner wall  614  and together walls  612 ,  614  define a fluid flow path  660  through the generally tubular body  610  from the inlet  620  to the outlet  630 . In the vicinity of the outlet  630 , the inner wall curves outwards  614   b  and increases in diameter causing a reduction in the cross section of the fluid flow path at the outlet  630 . The inner wall  614  continues beyond the outlet  630  and the end of the outer wall  612  of the nozzle  600  to a downstream nozzle end  600   b . The inner wall  614   b  is convex and is a Coanda surface i.e. it causes fluid that flows through the fluid flow path  660  to hug the surface of the inner wall  614   b  as it curves forming an annular flow at the outlet  630  and downstream nozzle end  600   b . In addition the Coanda surface  614  is arranged so a primary fluid flow exiting the outlet  630  is amplified by the Coanda effect. 
         [0118]    The hairdryer achieves the output and cooling effect described above with a nozzle which includes a Coanda surface to provide an amplifying region utilising the Coanda effect. A Coanda surface is a known type of surface over which fluid flow exiting an output orifice close to the surface exhibits the Coanda effect. The fluid tends to flow over the surface closely, almost ‘clinging to or bugging’ the surface. The Coanda effect is already a proven, well documented method of entrainment whereby a primary air flow is directed over the Coanda surface. A description of the features of a Coanda surface, and the effect of fluid flow over a Coanda surface, can be found in articles such as Reba, Scientific American, Volume 214, June 1963 pages 84 to 92. 
         [0119]    Advantageously, the assembly results in the entrainment of air surrounding the mouth of the nozzle such that the primary air flow is amplified by at least 15%, whilst a smooth overall output is maintained. 
         [0120]    By encouraging the fluid at the outlet  630  to flow along  616  the curved surface  614   b  of the inner wall to the downstream nozzle end  600   b , fluid is entrained  618  from outside the hairdryer  200  ( FIG. 8 c   ) by the Coanda effect. This action of entrainment increases the flow of air at the downstream nozzle end  600   b , thus the volume of fluid flowing at the downstream nozzle end  600   b  is magnified by the entrainment above what is processed by the hairdryer  200  through a fan unit  250  and heater  208 . 
         [0121]    When the nozzle  600  is attached to a hairdryer  200  as shown in  FIG. 8 a   , the fluid inlet  620  aligns with a primary fluid outlet  230  of the hairdryer. Hairdryer  200  has a second fluid flow path  280  through a central duct  282  but this is blocked by the nozzle  600 . In the example shown in  FIG. 2 a   , nozzle  100  blocked the second fluid flow path  280  at the upstream end  100   a  of the nozzle. In this example, the nozzle  600  uses an upstream continuation of curved wall  614   b  which curves inwards to form a rounded end  616  which blocks the second fluid flow path. 
         [0122]    In order to seal the nozzle fluid flow path  660  with respect to the primary fluid outlet  230 , the outer wall  612  of the nozzle is provided with a collar  612   a . The collar  612   a  is upstanding from the outer wall  612  so has a larger diameter than the outer wall and is designed to fit with ducting  282  within the hairdryer  200 . The collar  612   a  is upstream of the fluid inlet  620  of the nozzle  600 . A second collar  612   b  is ideally also provided downstream of the fluid inlet  620  and prevents fluid from the primary outlet  230  of the hairdryer flowing between the outer wall  612  of the nozzle and the hairdryer outlet  200   b.    
         [0123]      FIGS. 9 a  to 9 g    show an alternate double flow path nozzle  700  on a hairdryer  200 . In this embodiment, components illustrated and described with respect to  FIGS. 8 a  to 8 g    have like reference numbers. In this example, in addition to a fluid flow path  660  from an inlet  620  to an outlet  630 , a further fluid flow path  780  is provided. The inner wall  714  comprises a tube or bore through the nozzle  700  through which a fluid can flow from a further inlet  770  to a further outlet  790  along a further fluid flow path  780 . In this example, adjacent to and upstream of the fluid outlet  630  the inner wall  714  splits into an outer curved wall  714   b  along which fluid from the fluid flow path  660  flows to fluid outlet  630  and an inner straight wall  714   a  which continues to a further fluid outlet  790 . 
         [0124]    When the nozzle  700  is attached to a hairdryer a primary flow from a primary inlet  220  to a primary outlet  230  along a primary flow path  260  is in fluid communication with the nozzle inlet  620 . Fluid flows from the nozzle inlet  620  along fluid flow path  660  to nozzle outlet  630 . As the surface of the outer curved wall  714   b  is a Coanda surface, fluid that flows out of the outlet  630  is drawn to the surface and amplified by the Coanda effect which entrains fluid  618  from outside of the nozzle along the nozzle to a nozzle end  600   b . In addition, a second fluid flow path  280  is provided in the hairdryer  200  through which fluid is entrained by the action of fluid flowing in the primary fluid flow path  260 , 660  i.e. fluid that is drawn into the primary fluid flow path  260  directly by the fan unit  250 . This second fluid flow path  280  has an inlet  270  and an outlet  290 . The outlet  290  is in fluid communication with the further inlet  770  of the nozzle  700 . So fluid that is entrained into the second fluid flow path  280  by the action of the fan unit  250  flows along a further fluid flow path  780  the boundaries of which are defined by the inner wall  714 ,  714   b  of the nozzle  700  to a further outlet  790 . 
         [0125]    Thus, in this example the hairdryer emits a hot annular fluid which has a central cool core from the internally entrained fluid and an outer cool ring from the externally entrained fluid. 
         [0126]      FIGS. 10 a  to 10 e    show a further single flow path nozzle  10  which is similar to the one described with respect to  FIG. 8 . In this nozzle a fluid flow path  60  is provided from an inlet  20  to an outlet  30 . The inlet  20  is through an outer wall  12  of a generally tubular body  14  of the nozzle  10  between a first or upstream end  10   a  and a second or downstream end  10   b  of the nozzle  10 . The outlet  30  is a slit formed between the outer wall  12  and an inner wall  32  of the nozzle. 
         [0127]    The inner wall  32  is convex and formed by a bung  34  which is located in the downstream end  12   b  of the outer wall  12 . Fluid that flows through the fluid flow path  60  is funnelled by an upstream end  34   a  of the bung  34  towards the outlet  30 . As the inner wall  32  is convex, fluid that flows out of the outlet  30  is drawn to the surface  32  by the Coanda effect and this entrains fluid  18  from the environment around the nozzle  10 . 
         [0128]    The shape of the bung  34  at the downstream end  34   b  is generally rectangular so the fluid exits the nozzle in a generally rectangular profile. 
         [0129]    The rear or upstream end  10   a  of the nozzle has a cone shaped bung  70  so when the nozzle  10  is used in conjunction with hairdryer  200  (not shown), fluid from the second fluid flow path  280  is blocked by the cone shaped bung  70 . 
         [0130]      FIGS. 12 a  to 12 c    show a nozzle and hairdryer combination where the nozzle  1100  has a generally tubular body  1103  with a longitudinal axis D-D extending along the length of the body and having a first inlet  1102  and a second inlet  1104  into the fluid flow path  1106  of the nozzle  1100 . The hairdryer  1120  has a corresponding primary outlet  1122  and second primary outlet  1124  which provide fluid communication with the first inlet  1102  and the second inlet  1104  respectively. This arrangement means that the primary flow through the primary fluid flow path  1126  of the hairdryer has two outlet regions. The use of a nozzle  1100  on a hairdryer  1120  introduces a restriction to the flow through the hairdryer resulting in a drop in output by the hairdryer of up to around 4 l/s. By introducing a second primary outlet  1124  for the primary flow the drop in output is mitigated. 
         [0131]    The second inlet  1104  is similar to first inlet  1102  in that is extends in the direction of the longitudinal axis of the nozzle and radially round through outer wall  1110  of the generally tubular body  1103  of the nozzle  1100 . The second inlet  1104  consists of a number of discrete apertures  1104   a  separated by reinforcing struts  1104   b.    
         [0132]    Referring to  FIG. 12 a   , which shows a portion of a hairdryer having a primary fluid outlet comprising first  1122  and second  1124  primary outlets when there is no nozzle attached to the hairdryer  1120 , the second primary outlet  1124  is closed as it is not required to increase flow through the primary fluid flow path  1126  of the hairdryer  1120 . A closure  1130  is provided which occludes, blocks, covers or restricts the second primary outlet  1124 . The closure  1130  is biased into the closed position by a spring  1132 , in this example, which pushes against the closure  1124  to occlude the second primary outlet  1124 . The first  1122  and second  1124  primary outlets both comprise apertures and are spaced apart along the longitudinal axis D-D of the nozzle  1100 . 
         [0133]    Referring now to  FIG. 12 c   , the nozzle  1100  is provided with a lip  1108  which is upstanding from the generally tubular wall  1101  of the nozzle. The lip  1108  can be continuous or discontinuous around the perimeter of the generally tubular outer wall  1105  of the body  1103  of the nozzle  1100  and is of sufficient depth or height upstanding from the wall  1105  to firstly engage with the closure  1130  and secondly to allow the nozzle to be inserted up to the point of engagement of the lip  1108  with the closure  1130  without snagging of the nozzle  1100 . 
         [0134]    The lip in this example is formed from an O-ring which is held in a recess formed in the body  1103  of the nozzle. Alternatives will be apparent to the skilled person and include, but are not limited to an integral moulded lip, a plastic/hard rubber ring, a living hinge, an overmoulded lip and a push fit arrangement. 
         [0135]    The closure  1130  is ring shaped and has an S-shaped profile. Central to the ring is an aperture  1126  to enable fluid flowing through the primary fluid flow path  1126  of the hairdryer to exit the downstream end  1120   b  of the hairdryer from the first primary fluid outlet  1122  of the hairdryer. A first end  1125  of the S-shaped profile of the closure  1130  engages with one end of spring  1132  and provides the means by which the closure  1130  is biased into an occluded or closed position. A second end  1127  of the S-shaped profile protrudes into the fluid flow path  1129  of the hairdryer between the primary outlet  1122  and the downstream end  1120   b  of the hairdryer. This second end  1127  of the closure  1130  engages with the lip  1108  of the nozzle  1100  when the nozzle is inserted far enough into the downstream end  1120   b  of the hairdryer  1120  (see  FIG. 12 b   ) and as the nozzle is inserted past the point of engagement, the closure  1130  is pushed against the action of the spring  1132  and slides, opening the second primary outlet  1124  to allow fluid flowing in the primary fluid flow path  1126  to exit via either the first primary outlet  1122  or the second primary outlet  1124  thus mitigating any restriction on fluid flow through the hairdryer from the use of a nozzle. 
         [0136]    In order to prevent egress of fluid from the primary fluid flow path  1126  from the hairdryer outlet  1120   b  around the outside of the nozzle  1100 . The outer wall  1103  is provided with an upstanding collar  1110  that extends about the outer wall  1103  and seals the nozzle with respect to the hairdryer outlet  1120 . The collar  1110  additionally provides a point of friction between the nozzle and the hairdryer that retains the nozzle within the hairdryer. 
         [0137]    The nozzle  1100  has a downstream end  110   b  where fluid is output through a nozzle outlet  1112  and an upstream end  1100   a . In one embodiment the upstream end  1100   b  of the nozzle comprises an end wall  1114 . In this embodiment, the primary flow from the hairdryer is the only flow that is output from the nozzle outlet  1112 . Alternatively, the upstream end  1100   a  of the nozzle comprises an opening  1116  which provides a further nozzle inlet for a second fluid flow path  1140  in the hairdryer. The second fluid flow path is for fluid that is entrained into the hairdryer by the action of the fan unit (not shown) drawing fluid into the primary fluid flow path  1126 . The entrained fluid enters the hairdryer at a second inlet  1142 , flows along the second fluid flow path  1140  into the further nozzle inlet  1116 . The entrained fluid mixes with primary fluid flow within the nozzle before exiting at the nozzle outlet  1112 . Alternatively, the second fluid flow is provided with a further fluid flow path through the nozzle as described with respect to  FIGS. 3, 4, 5, 7 and 9  to provide isolated hot and cool fluid from the nozzle. 
         [0138]      FIGS. 13 a  to 13 d    show a different arrangement. In this example, the second primary outlet  1174  from the primary fluid flow path  1176  is in an end wall  1160  of the hairdryer  1150  rather than through an internal wall. 
         [0139]    Referring now to  FIG. 13 a   , the hairdryer has a generally tubular body  1152  having an inner wall  1154   a    1154   b  and an outer or external wall  1156 . At the downstream end  1150   b  of the hairdryer an end wall  1160 ,  1180  is provided between the inner  1154   b  and outer  1156  wall. The end wall is orthogonal to a longitudinal axis E-E of the body  1152  and includes a fixed portion  1160  and a moveable portion or closure  1180 . The closure  1180  is annular and is biased by a spring  1182  to be substantially flush with the fixed portion of the end wall  1160 . When a nozzle is inserted into the hairdryer  1150 , the closure  1180  is pushed against the spring  1182 , causing the spring to compress and open the second primary outlet  1174 . In this example, the closure  1180  is adjacent to the inner wall  1154   b  of the hairdryer however the closure could be located anywhere between the inner and outer walls. In addition, the closure need not be continuous around the end wall. 
         [0140]    Referring now to  FIG. 13 d   , the nozzle  1190  has a generally tubular body  1192  having an outer wall  1194 . A first inlet  1196  is provided in the outer wall  1194  between an upstream or first end  1190   a  and a downstream or second end  1190   b  of the nozzle but towards the upstream end  1190   a  of the nozzle. This first inlet  1196  is in fluid communication with a first primary outlet  1172  of the hairdryer provided in the inner wall  1154  of the body of the hairdryer and a fluid flow path  1197  is provided through the nozzle from the first inlet  1196  through the body  1192  of the nozzle to a nozzle outlet  1198  at the downstream end  1190   b  of the nozzle. The outer wall  1194  of the nozzle is designed to be insertable into the outlet end  1150   b  of the hairdryer. At the downstream end  1194   b  of the outer wall  1194  a hook shaped lip  1193  is provided. When the nozzle  1190  is inserted in the hairdryer, the hooked shaped lip  1193  covers the end of inner wall  1154   b  of the hairdryer and engages with closure  1180  pushing it against the action of the spring  1182 . In order to provide a second fluid flow path  1184  from the second opening  1174  to the downstream end  1190   b  of the nozzle, a collar  1195  is provided on the nozzle. When the nozzle is inserted into the hairdryer, the collar  1195  fits over the outer wall  1156  of the body  1152  of the hairdryer and forms together with the fixed portion of the end wall  1160  and the hook shaped lip  1193  a second fluid inlet  1184  for the nozzle which combines with fluid from the first inlet  1196  in the fluid flow path  1197  within the nozzle. 
         [0141]    The nozzle  1190  is inserted as shown in  FIGS. 13 b  and 13 c   ; the lip  1193  engages with the closure  1180  and forces the closure back against the action of the spring  1182  opening the second primary outlet  1174 . 
         [0142]      FIGS. 14 a  to 14 d    show an alternate arrangement for mitigating flow restriction when a nozzle  1200  is used on a hairdryer  1252 . In this example, insertion of a nozzle  1200  results in the primary fluid outlet  1250  of the hairdryer  1252  increasing in size. 
         [0143]    The nozzle  1200  has a generally tubular body  1202  with a longitudinal axis F-F extending along the length of the body  1202 . A fluid inlet  1208  comprising a number of apertures  1210  separated by struts  1212  has a length that extends in the direction of the longitudinal axis F-F of the nozzle  1200  and is located between a first or upstream end  1200   a  and a second or downstream end  1200   b  of the nozzle  1200  in an outer wall  1204  of the body  1202 . 
         [0144]    The hairdryer  1252  has a generally tubular body having an inner wall  1254   a ,  1254   b , an outer wall  1256  and a primary fluid flow path  1258  provided therebetween. The primary fluid flow path  1258  flows from a primary inlet  1220  to a primary outlet  1250  provided as an aperture between two sections of the inner wall  1254   a ,  1254   b  and then through a central bore  1260  in the body of the hairdryer  1252  to a hairdryer outlet  1262 . 
         [0145]    The primary outlet  1250  is formed from a fixed surface  1270  attached to the downstream section of inner wall  1254   b  and a moveable surface  1272  which is connected to an upstream section of the inner wall  1254   a . In order that the primary outlet  1250  can be opened, a moveable portion  1254   aa  of the upstream inner wall  1254   a  is slidably moveable against the direction of fluid flow at the primary fluid outlet  1250  towards the upstream end  1252   a  of the hairdryer  1252 . The upstream section of the inner wall  1254   a  and the moveable portion  1254   aa  form a lap joint  1282  ( FIG. 14 d   ) which is biased apart by a spring  1280  ( FIGS. 14 a  and 14 b   ). The moveable portion  1254   aa  has an internal surface which describes a duct  1262  within the hairdryer and is provided with a rim or lip  1264  which is upstanding from the duct  1262  and extends radially into the duct  1262 . When a nozzle  1200  is inserted into the outlet  1262  of the hairdryer, the upstream end  1200   a  of the outer wall  1204  of the nozzle engages with the rim or lip  1262  on the moveable portion  1254   aa  and pushes the moveable portion  1254   aa  against the biasing action of the spring  1280  so the moveable portion  1254   aa  slides towards the upstream inner wall  1254   a  and opens the primary fluid outlet  1250  ( FIGS. 14 c  and 14 d   ). 
         [0146]    When the nozzle  1200  is subsequently removed, the moveable portion  1254   aa  slides back towards the downstream end  1252   b  of the hairdryer  1252  causing the primary outlet  1250  to reduce back to its&#39; original size. 
         [0147]      FIGS. 15 a  and 15 b    show a hairdryer  170  and  15   c  and  15   d  a nozzle  190  attached to the hairdryer  170 . The hairdryer  170  has a body  177  that defines a duct  176 , a pair of handles  172 ,  173 , a primary inlet  171  in the upstream end  170   a  of the hairdryer and a fluid outlet  178  in the downstream end  170   b  of the hairdryer. 
         [0148]    A primary fluid is drawn into the primary inlet  171  and flows along a first handle  172  though a fan unit (not shown) which draws the fluid in, along a second handle  173  through a heater  174  and out of a primary outlet  175  into a duct  176  of the hairdryer to the fluid outlet  178 . A second fluid flow path  180  is provided from a second inlet  181  at the upstream end  170   a  of the hairdryer through the duct  176  to the hairdryer outlet  178 . Fluid is entrained into the second fluid flow path  180  by the action of the fan unit (not shown) drawing fluid into the primary inlet  171  to the primary outlet  175  and mixes or combines with the primary flow at the primary fluid outlet  175 . The fluid that flows through the duct  176  is a combined primary and entrained flow. 
         [0149]    In this example, not all of the primary flow flows through the heater  174  to the primary outlet  175 . A portion of the primary flow bypasses the heater  174  though an internal cooling duct  179  which is formed where the second handle  173  joins the body  177  and surrounds the duct  176 . The internal cooling duct  179  extends around the duct  176  from the primary outlet  175  to the downstream end  170   b  of the hairdryer and around 1 l/s of fluid bleeds through an annular opening  182  of the internal cooling duct  179  which surrounds the fluid outlet  178 . The internal cooling duct  179  has two functions, firstly it provides an insulation for the tubular wall that forms the body  177  and secondly it provides a cool annular ring of fluid that surrounds the combined fluid flow out of the fluid outlet  178 . 
         [0150]    Nozzle  190  ( FIG. 15 c   ) is essentially nozzle  100  ( FIGS. 1 a  to 1 f   ) with the addition of an outer collar  191  adapted to engage with the annular opening  182  of the hairdryer  170  and provide a cooling fluid flow path  192  from the annular opening  182  along a cooling fluid flow path  192  to a cooling outlet  193  of the nozzle  190 . The same reference numerals have been used for features that have been described with reference to  FIGS. 1 a  to 1 f    and that are in common with nozzle  190 . 
         [0151]    The nozzle  190  has a generally tubular body  110  which is insertable into a hairdryer at an upstream end  100   b . The downstream end  100   b  of the nozzle is generally rectangular and the nozzle  190  changes shape from tubular to rectangular outside the hairdryer  170 . The collar  191  surrounds the body  110  from the downstream end  100   b  of the nozzle to the point where the nozzle is inserted into the duct  176  of the hairdryer and generally maintains a constant distance between the body  110  and the collar  191 . 
         [0152]    When a nozzle  190  is attached to the hairdryer  170  ( FIGS. 15 c  and 15 d   ), the collar upstream end  191   a  abuts with the downstream end of the tubular body  177   a  of the hairdryer to provide fluid communication between the annular opening  182  of the internal cooling duct  179  and the cooling fluid flow path  192  of the nozzle  190  so fluid that flows along the internal cooling duct  179  flows into the cooling fluid flow path  192  to the nozzle cooling outlet  193 . 
         [0153]    As the nozzle  190  is a hot styling nozzle so a barrier  140  is provided to prevent entrainment along a second fluid flow path  180  of the hairdryer, all the fluid that flows out of the nozzle outlet  130  is hot. By having a cooling fluid flow path  192  which surrounds the nozzle fluid flow path  160  and the nozzle outlet  130 , the part of the nozzle that is gripped by a user to remove the nozzle  190  from the hairdryer  170  is cooled and the hot flow from the nozzle outlet  130  is surrounded by a cooling flow. 
         [0154]      FIGS. 16 a , 16 b , 16 h  to 16 k    all show a hairdryer  670  having a primary fluid flow path  671  which is processed by a fan unit  672  and a heater  673  second fluid flow path  680  which comprises fluid that has been entrained into the hairdryer by the action of the fan unit  672  drawing fluid into the primary fluid flow path  671 . 
         [0155]    Referring in particular to  FIGS. 16 h  and 16 i   , a primary fluid flow is drawn into the primary fluid flow path  671  at a primary inlet  674  and flows along a first handle  676  though a fan unit  672 , along a second handle  677  through a heater  673  and out of a primary outlet  675  into a duct  678  of the hairdryer to the fluid outlet  679 . A second fluid flow path  680  is provided from a second inlet  681  at the upstream end  670   a  of the hairdryer through the duct  678  to the hairdryer outlet  679 . Fluid is entrained into the second fluid flow path  680  by the action of the fan unit  672  drawing fluid into the primary inlet  674  to the primary outlet  675  and mixes or combines with the primary flow at the primary fluid outlet  675 . The fluid that flows through the duct  678  to the outlet  679  is a combined primary and entrained flow. 
         [0156]    The primary fluid outlet  675  is relatively large and unrestricted. In order to encourage entrainment into the second fluid flow path  680 , an attachment  685  is provided. The attachment  685  ( FIGS. 16 l  and 16 m   ) is inserted into the hairdryer outlet  679  and comprises a generally tubular body  686  between a first or upstream end  685   a  and a second or downstream end  685   b . In order to encourage entrainment by the Coanda effect, the attachment  685  is provided with a Coanda surface  687  at the upstream end  685   a . The Coanda surface  687  is in fluid communication with the primary fluid outlet  675  when the attachment is inserted in the hairdryer  670  ( FIGS. 16 j  and 16 k   ) and causes primary fluid to hug the Coanda surface  687  when the primary fluid flow exits the primary fluid outlet  675  into the nozzle fluid flow path  688  and to a nozzle outlet  689 . The downstream end  685   b  of the attachment  685  is provided with an upstanding lip  690  which protrudes from the downstream end  670   b  of the hairdryer and covers the downstream end  670   b  of the hairdryer. The nozzle outlet  689  is circular and has a smaller diameter than the hairdryer outlet  679 . 
         [0157]    Referring now to  FIGS. 16 c  to 16 g   , a second attachment  850  is provided. This second attachment  850  is a hot styling nozzle and only provides an outlet for the primary flow from the hairdryer  670 . 
         [0158]    The second attachment  850  has a generally tubular body  851  which defines a longitudinal axis G-G of the attachment from a first or upstream end  850   a  to a second or downstream end  850   b . At the upstream end  850   a , an end wall  852  is provided which is designed to block the second fluid flow path  680  of the hairdryer  670 . A fluid inlet  853  is provided in the body  851  downstream of the end wall  852  and fluid can flow from the fluid inlet  853  along a fluid flow path  854  to a fluid outlet  855  at the downstream end  850   b  of the nozzle. The nozzle  850  is designed to be partially insertable into hairdryer  670  such that the fluid inlet is in fluid communication with the primary fluid outlet  675 . The portion of the nozzle that is insertable is generally tubular and is provided with an upstanding lip of collar  856  around the body  850  which abuts the downstream end  670   b  of the hairdryer when the attachment  850  is inserted properly. Downstream of the lip  856 , the change of the attachment changes from generally circular to generally rectangular to provide a focused flow from the nozzle outlet  855 . 
         [0159]    When there is no nozzle of the first type of nozzle  685  attached to the hairdryer  670 , a primary fluid flow is augmented by an entrained flow through the second fluid flow path  680  and the total fluid output from the fluid outlet  679  is the combined value of the primary flow and the entrained flow. The second attachment  850  only allows primary flow from the hairdryer and blocks the entrained flow so, could suffer from a lower velocity of fluid output at the nozzle outlet  855 . However, this is mitigated as the upstream end  855   a  of the nozzle  855  is designed to sit in the duct  678  of the hairdryer  670  so it does not restrict flow from the primary outlet  675 . The upstream end of the nozzle body  851  has a curved wall  857  so turbulence and pressure losses as a result of the use of the second attachment  850  are minimised. This second nozzle  850  has the effect of opening up the amp gap or the primary fluid outlet  675 . 
         [0160]    The lip or collar  856 ,  690  has the effect of not only informing the user that the nozzle or attachment  850 ,  685  has been correctly inserted into the hairdryer outlet  679  but also provides a seal against fluid from the primary fluid outlet  675  exiting external to the nozzle or attachment  850 ,  685 . 
         [0161]      FIGS. 17 a  to 17 c    show a nozzle  900  attached to a conventional hairdryer  920 . The hairdryer  920  has a body  922  and a handle  924 . The body  922  includes a duct  923  that houses a fan unit  930  and a heater  940  and a fluid flow path  926  is provided from an inlet  928  located at the upstream end  920   a  of the hairdryer to an outlet  932  provided at a downstream end  920   b  of the hairdryer. In use, fluid is drawn through the fluid flow path  926  by the fan unit  930  from the inlet  928  to the outlet  932 . When there is no attachment, the hairdryer outlet  932  is circular. 
         [0162]    The nozzle  900  has an upstream end  900   a  which is inserted into duct  923  at the outlet  932  of the hairdryer  920  and a downstream end  900   b  which protrudes from the outlet  932  of the hairdryer  920 . The nozzle  900  has a convex outer surface  910  which curves inwards to a rounded point or dome at the upstream end  900   a  of the nozzle and at the downstream end  900   b  of the nozzle. The convex outer surface  910  of the nozzle together with the hairdryer outlet  932  define an annular fluid outlet or aperture  950  of the hairdryer at the downstream end  920   b  of the hairdryer. 
         [0163]    In the vicinity of the outlet  950 , the convex outer wall  910  curves outwards and increases in diameter causing a reduction in the cross section of the fluid flow path at the outlet  950 . The convex outer wall  910  continues beyond the outlet  950  and the downstream end  920   b  of the hairdryer to a downstream nozzle end  900   b . The convex outer wall  910  is a Coanda surface i.e. it causes fluid that flows through the fluid flow path  926  to hug the surface of the outer wall  910  as it curves forming an annular flow at the outlet  950  and downstream nozzle end  900   b . In addition the Coanda surface  910  is arranged so a fluid flow exiting the outlet  950  is amplified by the Coanda effect. 
         [0164]    The hairdryer achieves the output and cooling effect described above with a nozzle which includes a Coanda surface to provide an amplifying region utilising the Coanda effect. 
         [0165]    By encouraging the fluid at the outlet  950  to flow along the curved surface  910  of the outer wall to the downstream nozzle end  900   b , fluid is entrained  918  from outside the hairdryer  920  ( FIGS. 17 b  and 17 c   ) by the Coanda effect. This action of entrainment increases the flow of air at the downstream nozzle end  900   b , thus the volume of fluid flowing at the downstream nozzle end  900   b  is magnified by the entrainment above what is processed by the hairdryer  920  through a fan unit  930  and heater  940 . 
         [0166]    The entrainment provides an advantage as it results in the production of an annular ring of hot fluid which is surrounded by and the outer edges are partially cooled by the entrained cool fluid. 
         [0167]    The nozzle  900  is retained within the hairdryer outlet  932  by one of a number of methods such as providing a ring around the outer surface and attached thereto by a number of radially spaced struts, the ring engaging with the duct  922  when the nozzle  900  is partially inserted in the hairdryer outlet  932 . An alternative retention method is to use a central strut to support the nozzle. 
         [0168]      FIGS. 18 a  to 28 e    show an alternate nozzle  960  attached to a conventional hairdryer  920 . Features that have already been described with respect to  FIGS. 1 a  and 1 b    are provided with the same reference numerals. 
         [0169]    The nozzle  960  is provided with a collar  980  which surrounds the outer surface  970 . The internal surface  982  of the collar  980  and the outer surface  970  of the nozzle together define an entrained fluid flow path  984  through which fluid  978  that has been entrained from outside the hairdryer  920  by the action of the fan unit  930  drawing a fluid flow through the hairdryer to the annular outlet  990  formed by the convex outer surface  970  of the nozzle and the hairdryer outlet  932  can flow. 
         [0170]    The collar  980  has two portions, an upstream portion  986  which flares outwards and away from the body  922  of the hairdryer and a downstream portion  988  which is generally constant in diameter and follows the line of the convex outer surface  970  of the nozzle  960 . The flared end  986  is to increase the entrainment effect and the volume of fluid that flows through the entrained fluid flow path  984 . The downstream end  988  focuses the flow towards the Coanda surface namely the outer surface  970  of the nozzle to provide a focused ring of fluid output from the end of the nozzle. 
         [0171]    The entrained fluid  978  and fluid flow from the hairdryer fluid flow path  926  mix and combine at the downstream end  920   b  of the hairdryer and within the collar  980 . The collar  980  additionally provides a finger guard to prevent a person from touching the outlet  932  directly and the entrained flow  978  cools the surface of the collar  980  preventing the collar  980  getting hot. 
         [0172]    The nozzle is retained with respect to the hairdryer by one of a number of alternatives which include but are not limited to a felt seal, a bump stop, an o-ring, magnets, friction fit, a mechanical clip, snap fit or actuated snap fit. 
         [0173]    The hairdryers are preferably provided with a filter  222  ( FIGS. 2 b , 2 c  and 18 b   ) which covers at least the primary fluid flow inlet  220  of the hairdryer. The filter  222  is provided as is prevents ingress of dust, debris and hair into the primary fluid flow path upstream  260  of the fan unit  250  which includes a fan and a motor. These foreign objects could damage the motor and cause premature failure of the hairdryer. The filter  222  can cover the entire intake of the hairdryer i.e. both the primary fluid flow path  260  and the second fluid flow path  280  however this is not preferred as it interferes with a line of sight through the appliance. A line of sight through the appliance is restricted by the use of a nozzle on the appliance. 
         [0174]    The invention has been described in detail with respect to a nozzle for a hairdryer and a hairdryer comprising a nozzle however, it is applicable to any appliance that draws in a fluid and directs the outflow of that fluid from the appliance. 
         [0175]    The appliance can be used with or without a heater; the action of the outflow of fluid at high velocity has a drying effect. 
         [0176]    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. 
         [0177]    The invention is not limited to the detailed description given above. Variations will be apparent to the person skilled in the art.