Abstract:
A hair brushing appliance includes a housing, a motor located within the housing, a brush extending from the housing, and a transmission relaying output torque of the motor to the brush. A slippage mechanism associated with the transmission allows the motor to turn, should the brush stop turning such as might occur if the brush snags with long hair in use.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to hair curling brushes. More particularly, although not exclusively, the invention relates to an electric hair curling brush having a motor-driven roller and a clutch for preventing continuous rotation of the roller; should a user&#39;s hair become entangled upon the roller in use.  
         [0002]     Electric hair curling brushes comprise a bristled roller through which heated air is blown for passage through a plurality of apertures against a user&#39;s hair wrapped around the roller and passing in between the bristles. Whilst placing the bristled roller against the hair in such manner that the hair strands pass in between the bristles, the user grasps a handle extending longitudinally of the roller and turns the handle manually to cause the hair to be wrapped around the roller. An electric fan blows air across a heater for passage through the roller, out through the apertures in between the bristles to impinge upon the hair.  
         [0003]     A problem with such known hair curling brushes is in the requirement to manually turn the handle and thus the roller. One can only turn the handle throughout a limited angle without re-gripping the handle and turning again.  
         [0004]     A hair curling brush having a motor-driven roller would ameliorate the above problem, but would present another problem—namely that of hair-pulling and possible injury, should the user&#39;s hair become snagged upon the roller in use.  
       OBJECTS OF THE INVENTION  
       [0005]     It is an object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages and/or more generally to provide an improved hair curling brush having a motor-driven roller and safety clutch interposed between the motor and the roller.  
       DISCLOSURE OF THE INVENTION  
       [0006]     There is disclosed herein a hair curling appliance comprising: 
        a housing,     a motor located within the housing,     a brush extending from the housing,     a transmission relaying output torque of the motor to the brush, and     a slippage mechanism associated with the transmission to allow the motor to turn, should the brush stop turning in use.        
 
         [0012]     Preferably, the hair curling brush further comprises a heater and a fan blowing air across the heater to the roller.  
         [0013]     Preferably, the transmission comprises a gearbox.  
         [0014]     Preferably, the slippage mechanism comprises a clutch associated with gears in the gearbox.  
         [0015]     Preferably, the clutch comprises a plurality of profiled intermeshing teeth.  
         [0016]     Preferably, the appliance further comprises a spring biasing the profiled teeth into engagement with one another and wherein force applied by the spring upon the clutch defines a pre-set torque transmission limit of the gearbox.  
         [0017]     Preferably, the clutch is formed integrally with a gear of the gearbox. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:  
         [0019]      FIG. 1  is a schematic cross-sectional elevation of a hair curling appliance,  
         [0020]      FIG. 2  is a schematic parts-exploded perspective illustration of the hair curling appliance&#39;s gearbox,  
         [0021]      FIG. 3  is a schematic parts-exploded perspective illustration of the appliance,  
         [0022]      FIG. 4  is a schematic perspective illustration of the gearbox and motor, and  
         [0023]      FIG. 5  is a schematic cross-sectional elevation of the gearbox and motor of  FIG. 4 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]     In the accompanying drawings there is depicted schematically a hair curling appliance  10 . The appliance comprises a housing having a handle portion  12  by which the appliance is grasped in use. There is a bristled roller or brush  11  projecting from front end of the device  10  through which heated air is blown for delivery via a plurality of surface apertures as depicted.  
         [0025]     Situated immediately behind the brush  11  is cap a  39  behind which a roller gear  19  is located. As shown in  FIG. 3 , the roller gear  19  is drum-shaped having gear teeth about its rear-most periphery. A heater shroud  40  extends into the roller gear  19  and houses a heater  42  hating a number of radially projecting elongate heating fins as shown in  FIG. 3 .  
         [0026]     A fan motor  44  is mounted within a fan motor mounting frame  45  immediately behind the heater  42  and draws air in through a grille  48  that sits behind a removable end cap  49  upon which a filtering net  50  and filtering mesh  51  are positioned. Small capacitors  43  are associated with the fan motor  44  and/or heater  42 .  
         [0027]     The housing comprises a pair of housing halves  52  and  53  of moulded plastics material between which the above-described components are mounted.  
         [0028]     There is a brush rotation control button set  20  in a trigger position of the housing. A number of buttons  15  for adjusting the speed of the fan motor  44  and the heater  42  are also provided. There is a cold shot button  17  which when depressed cuts electric power to the heater  42 .  
         [0029]     At the bottom of the handle  12 , there is a power cord sleeve  13  and a hanging loop  14 . An electric power cord  54  extends through the power cord sleeve  13 . A cable tie  55  and connector  56  would be provided for the cord  54 .  
         [0030]     Also located within and supported between the housing halves  52  and  53  is a gearbox  16  comprising a gearbox casing upper  33  and a gearbox casing lower  22  each formed as a metal casting or plastics moulding. An electric motor  23  drives the gearbox which in turn drives the roller gear  19  to cause rotation of the brush  11 .  
         [0031]     Electric motor  23  has an output shaft passing through the gearbox casing lower  22  to receive a pinion  24 . The pinioned  24  drives the large-diameter teeth of an intermediate gear  38 . The small diameter teeth of the intermediate gear drive a clutch gear  25 . The clutch gear  25  is mounted slidably upon a shaft  27  having a retainer  28  at its bottom end that is fitted upon a boss  29  of the gearbox casing lower  22 . A coil spring  26  surrounds the shaft  27  to bias the clutch gear  25  upwardly. It should be noted that the thickness of the clutch gear  25  is less than that of the pinion  24  to enable continuous intermeshing of the pinion with the clutch gear, should the clutch gear move up and down along shaft  27 . The clutch gear has a number of profiled clutch teeth  31  formed integrally therewith. The clutch teeth press against and mesh with correspondingly profiled clutch teeth at the underside of a crown wheel  30 . The crown wheel rotates upon the shaft  27  and intermeshes with a pinion  34 . The pinion  34  is fixed upon a shaft  35  at the opposite end of which another pinion  36  is fixed. Pinion  36  engages with the roller gear  19 .  
         [0032]     The spring  26  maintains contact between the profiled teeth  31  during normal use of the appliance. Should the user&#39;s hair becomes snagged about the brush  11 , there will be a reaction torque build-up in the gearbox and the spring  26  will be unable to maintain engagement between the profiled teeth. That is, the teeth will ride upon one another as the clutch gear  25  continues to rotate by action of the motor  23 . This might produce an audible and/or tactile feedback to the user whereupon she can release finger pressure from the brush rotation control button.  
         [0033]     It should be appreciated that modifications and alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention. For example, instead of providing a clutch with profiled teeth, a flat plate clutch might be provided. Furthermore, instead of providing a clutch, there might be provided a pair of pulleys about which a belt extends—which belt might slip upon one or both of the pulleys, should the brush becomes snagged.