Abstract:
A hairdryer includes 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 the primary fluid flow drawn through the primary fluid inlet; and a nozzle attachable to the body, the nozzle comprising a nozzle fluid inlet for receiving the primary fluid flow from the primary fluid outlet, and a nozzle fluid outlet for emitting the primary fluid flow, and wherein the nozzle is configured to inhibit the emission of the fluid flow from the fluid outlet.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of United Kingdom Application No. 1211837.8, filed Jul. 4, 2012, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     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 
     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 
     According to a first 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 the primary fluid flow drawn through the primary fluid inlet, and a nozzle attachable to the body, the nozzle comprising a nozzle fluid inlet for receiving the primary fluid flow from the primary fluid outlet, and a nozzle fluid outlet for emitting the primary fluid flow, and wherein the nozzle is configured to inhibit the emission of the fluid flow from the fluid outlet. 
     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. 
     The primary fluid flow path starts at a primary fluid inlet into the hairdryer i.e. a primary fluid inlet through which a primary fluid flow enters the hairdryer. 
     Preferably, the nozzle is configured to inhibit the generation of the fluid flow. 
     It is preferred that the nozzle comprises means for inhibiting the flow of fluid along the fluid flow path to the fluid outlet. 
     Preferably, the means for inhibiting the flow of fluid along the flow path to the fluid outlet comprises a bather which is located within the fluid flow path when the nozzle is attached to the hairdryer. 
     It is preferred that the barrier is located at an end of the nozzle. 
     Preferably, the barrier is substantially orthogonal to the longitudinal axis of the nozzle. Alternatively, the barrier is inclined to the longitudinal axis of the nozzle. 
     It is preferred that the primary fluid outlet is configured to emit the primary fluid flow into the fluid flow path, and wherein the nozzle comprises a first end which is insertable into the fluid flow path through the fluid outlet, 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. 
     Preferably, wherein the nozzle fluid inlet comprises at least one aperture extending at least partially about the longitudinal axis of the nozzle. It is preferred that the nozzle fluid inlet comprises a plurality of apertures extending circumferentially about the longitudinal axis of the nozzle. 
     Preferably, 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. 
     It is preferred that the nozzle comprises a side wall between the first end and the second end of the nozzle, 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. It is preferred that the nozzle fluid inlet is formed in the side wall. 
     Preferably, the side wall extends about an inner wall, and wherein the nozzle fluid inlet is located between the walls of the nozzle. It is preferred that the inner wall is tubular in shape. 
     Preferably, the inner wall extends from the first end to the second end. It is preferred that the second end of the nozzle comprises the nozzle fluid outlet. 
     It is preferred that the nozzle fluid outlet is located between the first end and the second end of the nozzle. 
     According to a second 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 the primary fluid flow drawn through the primary fluid inlet, wherein the nozzle is attachable to the body, the nozzle comprising a nozzle fluid inlet for receiving the primary fluid flow from the primary fluid outlet, and a nozzle fluid outlet for emitting the primary fluid flow, and wherein the nozzle is configured to inhibit the emission of the fluid flow from the fluid outlet. 
     The primary fluid flow path starts at a primary fluid inlet into the hairdryer, i.e. a primary fluid inlet through which a primary fluid flow enters the hairdryer. 
     Preferably, the nozzle is configured to inhibit the generation of the fluid flow. 
     It is preferred that the nozzle comprises means for inhibiting the flow of fluid along the fluid flow path to the fluid outlet of the hairdryer. 
     Preferably, the means for inhibiting the flow of fluid along the flow path to the fluid outlet comprises a bather which is located within the fluid flow path when the nozzle is attached to the hairdryer. 
     It is preferred that the barrier is located at an end of the nozzle. 
     Preferably, the barrier is substantially orthogonal to the longitudinal axis of the nozzle. 
     Alternatively, the barrier is inclined to the longitudinal axis of the nozzle. 
     Preferably, the nozzle comprises a first end which is insertable into the fluid flow path through the fluid outlet, 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. 
     Preferably, the nozzle fluid inlet comprises a plurality of apertures extending circumferentially about the longitudinal axis of the nozzle. 
     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. 
     Preferably, the nozzle comprises a side wall between the first end and the second end of the nozzle, 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. 
     It is preferred that the side wall is tubular in shape. 
     Preferably, the nozzle fluid inlet is formed in the side wall. 
     It is preferred that the side wall extends about an inner wall, and wherein the nozzle fluid inlet is located between the walls of the nozzle. 
     Preferably, the inner wall is tubular in shape. It is preferred that the inner wall extends from the first end to the second end. 
     It is preferred that the second end of the nozzle comprises the nozzle fluid outlet. 
     Preferably, the nozzle fluid outlet is located between the first end and the second end of the nozzle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example and with reference to the accompanying drawings, of which: 
         FIGS. 1   a    1   f  show various representations of a single flow path nozzle according to the invention; 
         FIGS. 2   a  to  2   c  show various representations of a single flow path nozzle attached to a hairdryer; 
         FIGS. 3   a  to  3   d  show a nozzle with an end valve; 
         FIG. 4   a  shows an alternate single flow path nozzle attached to a hairdryer; 
         FIGS. 4   b  to  4   g  show an alternate single flow path nozzle; 
         FIGS. 5   a  to  5   e  show a further single flow path nozzle; 
         FIGS. 6   a  to  6   f  show another single flow path nozzle with a hairdryer; 
         FIGS. 7   a  to  7   c  show a nozzle and hairdryer having two inlets into a single flow path; 
         FIGS. 8   a  to  8   d  show an alternate two outlet arrangement; 
         FIGS. 9   a  to  9   d  show a further nozzle and hairdryer combination; 
         FIGS. 10   a  to  10   g  show yet another single flow path nozzle and hairdryer; 
         FIGS. 10   h  and  10   i  show the hairdryer without a nozzle; and 
         FIGS. 10   j  to  10   m  show a further attachment with a hairdryer. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       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 . 
     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 . 
     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. 
       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 . 
     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 . 
     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 . 
     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 . 
     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. 
     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. 
     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. 
     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. 
     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. 3   a  to  3   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. 3   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 . 
     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. 3   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. 
     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. 
     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. 
       FIGS. 6   a  to  6   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 . 
     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. 6   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 . 
     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. 
       FIGS. 4   a  to  4   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 . 
     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. 
     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. 
     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 ‘hugging’ 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. 
     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 
     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. 4   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 . 
     When the nozzle  600  is attached to a hairdryer  200  as shown in  FIG. 4   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. 
     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.    
       FIGS. 5   a  to  5   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. 
     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 . 
     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. 
     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 . 
       FIGS. 7   a  to  7   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. 
     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.    
     Referring to  FIG. 7   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 . 
     Referring now to  FIG. 7   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 . 
     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. 
     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. 7   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. 
     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. 
     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 . 
       FIGS. 8   a  to  8   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. 
     Referring now to  FIG. 8   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. 
     Referring now to  FIG. 8   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. 
     The nozzle  1190  is inserted as shown in  FIGS. 8   b  and  8   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 . 
       FIGS. 9   a  to  9   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. 
     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 . 
     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 . 
     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. 9   a  and  9   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. 9   c  and  9   d ). 
     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. 
       FIGS. 10   a ,  10   b ,  10   h  to  10   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 . 
     Referring in particular to  FIGS. 10   h  and  10   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. 
     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. 10   l  and  10   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. 10   j  and  10   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 . 
     Referring now to  FIGS. 10   c  to  10   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 . 
     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 . 
     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 . 
     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 . 
     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. 
     The hairdryers are preferably provided with a filter  222  ( FIGS. 2   b  and  2   c ) 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. 
     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. 
     The appliance can be used with or without a heater; the action of the outflow of fluid at high velocity has a drying effect. 
     The fluid that flows through the appliance is generally air, but may be a different combination of gases or gas and can include additives to improve performance of the appliance or the impact the appliance has on an object the output is directed at for example, hair and the styling of that hair. 
     The invention is not limited to the detailed description given above. Variations will be apparent to the person skilled in the art.