Abstract:
A hand held appliance comprising a fluid flow path extending from a fluid inlet into the appliance to a fluid outlet from the appliance, the fluid flow path being at least partially defined by a wall, a switch mechanism housed by the wall having a cooperating externally accessible actuating button and a switch cover extending within the wall and containing the switch mechanism. The switch cover may maintain a spatial location of the switch mechanism relative to the actuating button. The switch cover may encase the switch mechanism. The switch cover may isolate the switch mechanism from the fluid flow path. The switch cover may maintain a spatial location of the switch mechanism relative to the wall. The switch cover may be curved towards an upstream end to reduce disturbance to the flow of fluid within the fluid flow path.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of United Kingdom Application No. 1508811.5, filed May 22, 2015, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    This invention relates to a hand held appliance and in particular a hair care appliance. 
       BACKGROUND OF THE INVENTION 
       [0003]    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 inlet to the blower. The fan and heater require power in order to function and this is provided via internal wiring from either a mains power cable or batteries attached to the appliance. 
         [0004]    Conventionally, a hairdryer has a body and a handle with a fluid flow path within the body and the controlling electronics within the handle i.e. removed from the fluid flow path. However, there are hairdryers where at least some of the fluid flows in the vicinity of the electronic controls and this can cause difficulties particularly when the hairdryer is used in humid environments. 
       SUMMARY OF THE INVENTION 
       [0005]    According to embodiments of the invention, a hand held appliance comprises a fluid flow path extending from a fluid inlet into the appliance to a fluid outlet from the appliance, the fluid flow path being at least partially defined by a wall, a switch mechanism housed by the wall having a cooperating externally accessible actuating button and a switch cover extending within the wall, the switch cover housing the switch mechanism. 
         [0006]    Preferably, the switch cover maintains a spatial location of the switch mechanism relative to the actuating button. 
         [0007]    In a preferred embodiment, the switch cover encases the switch mechanism. 
         [0008]    Preferably, the switch cover isolates the switch mechanism from the fluid flow path. 
         [0009]    In a preferred embodiment, the switch cover maintains a spatial location of the switch mechanism relative to the wall. 
         [0010]    Preferably, the switch cover is curved towards an upstream end to reduce disturbance to the flow of fluid within the fluid flow path. 
         [0011]    In a preferred embodiment, the wall has an inner surface and an outer surface, the fluid flow path being at least partly defined by the inner surface of the wall wherein, the inner surface of the wall comprises a lip which extends from the inner surface. 
         [0012]    Preferably, the lip engages with the switch cover to define a location of the switch cover with respect to the wall. 
         [0013]    In a preferred embodiment, the lip engages with the switch mechanism to define a location of the switch mechanism with respect to the wall. 
         [0014]    Preferably, the lip forms a part of a labyrinth seal around the switch mechanism. 
         [0015]    In a preferred embodiment, the switch cover forms another part of a labyrinth seal around the switch mechanism. 
         [0016]    Preferably, the switch mechanism includes an activation knob which cooperates with the externally accessible actuating button. 
         [0017]    In a preferred embodiment, the switch cover additionally houses a second switch. 
         [0018]    Preferably, the appliance is a hair care appliance. 
         [0019]    Preferably, the hair care appliance is a hairdryer. Alternatively, the hair care appliance is a hot styling appliance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0021]      FIG. 1  shows a hairdryer according to the invention; 
           [0022]      FIG. 2  shows a cross section through the hairdryer of  FIG. 1 ; 
           [0023]      FIG. 3  shows a further cross section through the hairdryer of  FIG. 1 ; 
           [0024]      FIG. 4  shows an exploded view of some of the internal components of a hairdryer according to the invention; 
           [0025]      FIG. 5  is a further cross section through the handle of hairdryer shown in  FIG. 1 ; 
           [0026]      FIG. 6  is an enlarged view of a cross section through the handle of hairdryer shown in  FIG. 1 ; and 
           [0027]      FIG. 7  is an enlarged view of the cross-section shown in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]      FIGS. 1, 2 and 3  show a hairdryer  10  with a handle  20  and a body  30 . The handle has a first end  22  which is connected to the body  30  and a second end  24  distal from the body  30  and which includes a primary fluid inlet  40 . Power is supplied to the hairdryer  10  via a cable  50 . At a distal end of the cable  50  from the hairdryer  10  a plug (not shown) is provided, the plug may provide electrical connection to mains power or to a battery pack for example. 
         [0029]    The handle  20  has an outer wall  200  which extends from the body  30  to a distal end  24  of the handle. At the distal end  24  of the handle an end wall  210  extends across the outer wall  200 . The cable  50  enters the hairdryer through this end wall  210 . The primary fluid inlet  40  in the handle  20  includes first apertures that extend around and along  42  the outer wall  200  of the handle and second apertures that extend across  46  and through the end wall  210  of the handle  20 . The cable  50  is located approximately in the middle of the end wall  210  so extends from the centre of the handle  20 . The handle  20  has a longitudinal axis X-X along which the outer wall  200  extends from the body  30  towards the distal end  24 . The handle  20  includes an outer wall  200  which is gripped by a user and an inner wall  220  which extends within the outer wall  200 . 
         [0030]    Downstream of the primary fluid inlet  40 , a fan unit  70  is provided. The fan unit  70  includes a fan and a motor. The fan unit  70  draws fluid through the primary fluid inlet  40  towards the body  30  through a primary fluid flow path  400  that extends from the primary fluid inlet  40  and into the body  30  where the handle  20  and the body  30  are joined  90 . The body  30  has a first end  32  and a second end  34 , the primary fluid flow path  400  continues through the body  30  towards the second end  34  of the body, around a heater  80  and to a primary fluid outlet  440  where fluid that is drawn in by the fan unit exits the primary fluid flow path  400 . The primary fluid flow path  400  is non linear and flows through the handle  20  in a first direction and through the body  30  in a second direction which is orthogonal to the first direction. 
         [0031]    The body  30  includes an outer wall  360  and an inner duct  310 . The primary fluid flow path  400  extends along the body from the junction  90  of the handle  20  and the body  30  between the outer wall  360  and the inner duct  310  towards the primary fluid outlet  440  at the second end  34  of the body  30 . 
         [0032]    Another fluid flow path  300  is provided within the body  30 ; this flow is not directly processed by the fan unit  70  or the heater  80  but is drawn into the hairdryer  10  by the action of the fan unit producing the primary flow through the hairdryer. This fluid flow is entrained into the hairdryer by the fluid flowing through the primary fluid flow path  400 . 
         [0033]    The first end  32  of the body includes a fluid inlet  320  and the second end  34  of the body includes a fluid outlet  340 . Both the fluid inlet  320  and the fluid outlet  340  are at least partially defined by the inner duct  310  which is an inner wall of the body  30  and extends within and along the body. A fluid flow path  300  extends within the inner duct  310  from the fluid inlet  320  to the fluid outlet  340 . At the first end  32  of the body  30 , a side wall  350  extends between the outer wall  360  and the inner duct  310 . This side wall  350  at least partially defines the fluid inlet  320 . The primary fluid outlet  440  is annular and surrounds the fluid flow path  300 . 
         [0034]    A printed circuit board (PCB)  75  including the control electronics for the hairdryer is located in the body  30  near the side wall  350  and fluid inlet  320 . The PCB  75  is ring shaped and extends round the inner duct  310  between the inner duct  310  and the outer wall  360 . The PCB  75  extends about the fluid flow path  300  and is isolated from the fluid flow path  300  by the inner duct  310 . 
         [0035]    The PCB  75  controls parameters such as the temperature of the heater  80  and the speed of rotation of the fan unit  70 . Internal wiring (not shown) electrically connects the PCB  75  to the heater  80  and the fan unit  70  and the cable  50 . The internal wiring includes a live wire  112  and a neutral wire  122  that extend from the cable towards the switch mechanism. Control buttons  62 ,  64  are provided and connected to the PCB  75  to enable a user to select from a range of temperature settings and flow rates for example. The control buttons  62 ,  64  are actuated by a user to change the state of a parameter of the hairdryer. 
         [0036]    In use, fluid is drawn into the primary fluid flow path  400  by the action of the fan unit  70 , is optionally heated by the heater  80  and exits from the primary fluid outlet  440 . This processed flow causes fluid to be entrained into the fluid flow path  300  at the fluid inlet  320 . The fluid combines with the processed flow at the second end  34  of the body. In the example shown in  FIG. 3 , the processed flow exits the primary fluid outlet  440  and the hairdryer as an annular flow which surrounds the entrained flow that exits from the hairdryer via the fluid outlet  340 . Thus fluid that is processed by the fan unit and heater is augmented by the entrained flow. 
         [0037]    Referring now to  FIGS. 2 to 7  in particular, the invention will now be described. The primary fluid flow path  400  flows from the primary fluid inlet  40  through the handle  20  and into the body  30  to the primary fluid outlet  400 . On the handle, a first set of control buttons  62  are provided. These control buttons  62  for example include an on/off button  62   a  and a cold shot button  62   b . Each of the control buttons  62   a , 62   b  cooperates with a switch mechanism. In this example, the on/off control button  62   a  cooperates with a switch mechanism  100  such that activation of the on/off control button  62   a  causes activation of the switch mechanism  100  via an activation knob  102 . When a user activates the on/off control button  62   a , the on/off control button slides and engages with the activation knob  102  moving it from the off position to the on position or vice versa. 
         [0038]    The control buttons  62   a ,  62   b  cooperate with their respective switches  100 ,  120  through apertures  202 ,  204  in the outer wall  200 . The control buttons  62   a ,  62   b  engage with their respective switches directly or indirectly. In this embodiment the control buttons  62   a ,  62   b  engage indirectly with their switches via an switch assembly  150  which forms part of an inner wall  220  of the handle  20 . The switch assembly  150  is a flexible barrier to block ingress of dirt etc. into the fluid flow path. The switch assembly  150  engages directly with both the control button  62   a  and the activation knob  102  so any movement of the control button  62   b  is reflected by a corresponding movement of the activation knob  102 . 
         [0039]    Alternatively, the control buttons  62   a , 62   b  engage directly with their respective switches  100 , 120  in which case the inner wall  220  and the switch assembly  150  can be dispensed with. In this embodiment, the switch cover  110  is attached to an inner surface  200   a  of the outer wall  200  of the handle  20 . 
         [0040]    The switch mechanism  100  is housed within a switch cover  110  which is attached to an inner surface  220   a  of the inner wall  220  of the handle  20 . The switch cover  110  has a number of functions: to retain the switch mechanism  100  in its location with respect to the control button  62   a , to provide a controlled change in cross section for the fluid flow path  400 , and to reduce the chance of dirt and fluid ingress into the controls of the hairdryer. 
         [0041]    The switch cover  110  is attached to the inner wall  220 . The inner wall  220  is provided with an aperture  226  through which the activation knob  102  of switch  100  protrudes in order to cooperate with the control button  62   a . This in turn retains the switch mechanism  100  in position with respect to the control button  62   a  either by direct contact between the activation knob  102  and the control button  62   a  or via the switch assembly  150 . 
         [0042]    The inner surface  220   a  of the inner wall  220  is shaped to receive and retain the switch cover  110 . The inner surface  220   a  is provided with a lip  222  which extends radially inwards of the inner wall  220 . The switch cover  110  has an outer edge  140  which extends over the lip  222  and is retained in position via screws  116  which engage with screw holes  224  in the lip  222 . The lip  222  engages with the switch cover  110  to define a location of the switch cover  110  with respect to the inner wall  220 . 
         [0043]    In addition to housing the switch mechanism  100 , the switch cover  110  routes a live wire  112  through a wire holder  124  and into the switch mechanism  100  to enable the hairdryer to be switched on and off. The neutral wire  122  ( FIG. 5 ) is routed passed the switch mechanism  100  and retained in a position using a wire clip  114 . 
         [0044]    A second switch comprising a PCB extension  120  which includes an electronic switch  126  to enable a user to activate and deactivate the cold shot button  62   b  is also housed within the switch cover  110 . The switch cover  110  additionally maintains the spatial location of this switch with respect to the control button  62   b.    
         [0045]    The switch cover  110  is shaped to reduce disturbance of fluid flowing within the primary fluid flow path  400 . The switch cover  110  has an upstream end  110   a  which is positioned towards the primary fluid inlet  40  and a downstream end  110   b  which is positioned towards the primary fluid outlet  440 . The upstream end  110   a  curves away from the inner surface  220   a  of the inner wall  220  providing a gradual decrease in the cross-sectional area of the primary fluid flow path  400  to provide room to accommodate the switch  100 . This causes less disturbance to the flow of fluid which reduces pressure loss and noise created by the switch cover  110 . 
         [0046]    The combination of the lip  222  and the switch cover  110  provides a convoluted path or a labyrinth seal to prevent fluid and dirt from entering the cavity  118  housing the switch mechanism  100 . The lip  222  enables the switch cover  110  and the switch mechanism  100  to be accurately positioned with respect to the inner wall  220  of the handle  20  and to the control button  62   a.    
         [0047]    The invention has been described in detail with respect to a hairdryer however, it is applicable to any appliance that draws in a fluid and directs the outflow of that fluid from the appliance. 
         [0048]    The appliance can be used with or without a heater; the action of the outflow of fluid at high velocity has a drying effect. 
         [0049]    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. 
         [0050]    The invention is not limited to the detailed description given above. Variations will be apparent to the person skilled in the art.