Abstract:
A drying apparatus such as a hand dryer has a casing, a fan located within the casing and capable of creating an airflow, and an inlet arranged in the casing through which air is drawn into the apparatus by the fan. At least one outlet opening communicates with the fan and is arranged in the casing so as to direct an airflow towards an object to be dried. The inlet comprises at least one inlet opening and a corresponding shield member which is spaced apart from and overlies the inlet opening such that air drawn into the apparatus by the fan passes through the inlet opening and is then deflected around the shield member. This allows air to be drawn freely into the casing while preventing objects which might cause damage to a filter or the fan or motor from being inserted into the casing via the inlet.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a national stage application under 35 USC 371 of International Application No. PCT/GB07/000106, filed Jan. 16, 2007, which claims the priority of United Kingdom Application No. 0600869.2, filed Jan. 17, 2006, the contents of both of which prior applications are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to drying apparatus. Particularly, but not exclusively, the invention relates to a hand dryer in which air is drawn into a casing via an inlet and emitted through at least one opening in the casing. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is known to provide a filter immediately downstream of the inlet to remove any debris which may be drawn into the drying apparatus via the inlet. It is also known to provide a simple passageway leading from the inlet to the motor and fan unit which draws the airflow into the casing. One of the problems of the prior art is that the filter, or the motor and fan unit, can be accessible from outside the casing and so can be vulnerable to damage. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the invention to provide drying apparatus which is less prone to damage than prior art apparatus. 
         [0005]    The invention provides drying apparatus having a casing, a fan located within the casing and capable of creating an airflow, an inlet arranged in the casing through which air is drawn into the apparatus by the fan, and at least one outlet opening communicating with the fan and arranged in the casing so as to direct an airflow towards an object to be dried, wherein the inlet comprises at least one inlet opening and a corresponding shield member which is spaced apart from and overlies the inlet opening such that air drawn into the apparatus by the fan passes through the inlet opening and is then deflected around the shield member. 
         [0006]    The provision of a shield member which is spaced apart from but overlies the inlet opening allows air to be drawn freely into the casing whilst preventing objects which might cause damage to a filter or the fan or motor from being inserted into the casing via the inlet. The shield member also provides some protection against fire damage in the event of a flame being placed beneath the drying apparatus. 
         [0007]    Preferably, the shield member has substantially the same shape as the inlet opening and, more preferably, the shield member overlaps at least a part of the periphery of the inlet opening. This arrangement prevents there being a direct line of access to the filter, fan or motor via the inlet which reduces the risk of deliberate damage being inflicted on these components. 
         [0008]    Preferably, the shield member carries a vane which projects towards, and more preferably terminates in, the plane of the inlet opening. The provision of the vane helps to divert the incoming airflow more smoothly around the shield member and improves the efficiency of the apparatus. 
         [0009]    In a preferred embodiment, the inlet comprises a plurality of inlet openings, the preferred number of openings being between three and six. This allows the size of each inlet opening to be kept relatively small whilst permitting a suitable flow of air to enter the casing via the inlet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    An embodiment of the invention in the form of a hand dryer will now be described with reference to the accompanying drawings, in which: 
           [0011]      FIG. 1  is a side view of a hand dryer according to the invention; 
           [0012]      FIG. 2  is a perspective view from above of the hand dryer of  FIG. 1 ; 
           [0013]      FIG. 3  is a side sectional view of the hand dryer of  FIG. 1 ; 
           [0014]      FIG. 4  is a side sectional view, shown on an enlarged scale, of the upper ends of the air ducts forming part of the hand dryer of  FIG. 1 ; 
           [0015]      FIG. 5  is a perspective view from below of the hand dryer of  FIG. 1 ; 
           [0016]      FIG. 6  is an underneath view of the hand dryer of  FIG. 1 ; and 
           [0017]      FIG. 7  is a section taken on line VII-VII of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Referring firstly to  FIGS. 1 and 2 , the hand dryer  10  shown in the drawings comprises an outer casing  12  having a front wall  14 , a rear wall  16 , an upper face  18 , a lower face  19  and side walls  20 ,  22 . The rear wall  16  can incorporate fixing devices (not shown) for securing the hand dryer  10  to a wall or other structure prior to use. An electrical connection (not shown) is also provided on the rear wall or elsewhere on the casing  12 . A cavity  30  is formed in the upper part of the casing  12  as can be seen from  FIGS. 1 and 2 . The cavity  30  is open at its upper end and delimited thereat by the top of the front wall  14  and the front of the upper face  18 . The space between the top of the front wall  14  and the front of the upper face  18  forms a cavity entrance  32  which is sufficiently wide to allow a user&#39;s hands to be introduced to the cavity  30  through the cavity entrance  32 . The cavity  30  is also open to the sides of the hand dryer  10  by appropriate shaping of the side walls  20 ,  22 . 
         [0019]    The cavity  30  has a front wall  34  and a rear wall  36  which delimit the cavity  30  to the front and rear respectively. Located in the lowermost end of the cavity  30  is a drain  38  which communicates with a reservoir (not shown) located in the lower part of the casing  12 . The purpose of the drain and reservoir will be described below. 
         [0020]    As shown in  FIG. 3 , a motor (not shown) is located inside the casing  12  and a fan  40 , which is driven by the motor, is also located inside the casing  12 . The motor is connected to the electrical connection and is controlled by a controller  41 . The inlet  42  of the fan  40  communicates with an air inlet  44  formed in the casing  12 . The inlet  44  will be described in more detail below. A filter  46  is located in the air passageway connecting the air inlet  44  to the fan inlet  42  so as to prevent the ingress of any debris which might cause damage to the motor or the fan  40 . The outlet of the fan  40  communicates with a pair of air ducts  50 ,  52  which are located inside the casing  12 . The front air duct  50  is located primarily between the front wall  14  of the casing  12  and the front wall  34  of the cavity  30 , and the rear air duct  52  is located primarily between the rear wall  16  of the casing  12  and the rear wall  36  of the cavity  30 . 
         [0021]    The air ducts  50 ,  52  are arranged to conduct air from the fan  40  to a pair of opposed slot-like openings  60 ,  62  which are located in the front and rear walls  34 ,  36  respectively of the cavity  30 . The slot-like openings  60 ,  62  are arranged at the upper end of the cavity  30  in the vicinity of the cavity entrance  32 . The slot-like openings  60 ,  62  are each configured so as to direct an airflow generally across the cavity entrance  32  towards the opposite wall of the cavity  30 . The slot-like openings  60 ,  62  are offset in the vertical direction and angled towards the lowermost end of the cavity  30 . 
         [0022]      FIG. 4  shows the upper ends of the air ducts  50 ,  52  and the slot-like openings  60 ,  62  in greater detail. As can be seen, the walls  54   a ,  54   b  of the air duct  50  converge to form the slot-like opening  60  and the walls  56   a ,  56   b  of the air duct  52  converge to form the slot-like opening  62 . In this embodiment, the slot-like opening  60  has a constant width of 0.3 mm and the slot-like opening  62  has a constant width of 0.4 mm. It is possible to arrange for one or both of the slot-like openings  60 ,  62  to have a non-constant width; for example, the width of the slot-like opening  62  may increase towards the centre of the apparatus to a width of approximately 0.7 mm. 
         [0023]    Sensors  64  are positioned in the front and rear walls  34 ,  36  of the cavity  30  immediately below the slot-like openings  60 ,  62 . These sensors  64  detect the presence of a user&#39;s hands which are inserted into the cavity  30  via the cavity entrance  32  and are arranged to send a signal to the motor when a user&#39;s hands are introduced to the cavity  30 . As can be seen from  FIGS. 1 and 3 , the walls  54   a ,  54   b ,  56   a ,  56   b  of the ducts  50 ,  52  project slightly beyond the surface of the front and rear walls  34 ,  36  of the cavity  30 . The inward projection of the walls  54   a ,  54   b ,  56   a ,  56   b  of the ducts  50 ,  52  reduces the tendency of the user&#39;s hands to be sucked towards one or other of the walls  34 ,  36  of the cavity, which enhances the ease with which the hand dryer  10  can be used. The positioning of the sensors  64  immediately below the inwardly projecting walls  54   a ,  54   b ,  56   a ,  56   b  of the ducts  50 ,  52  also reduces the risk of the sensors  64  becoming dirty and inoperative. 
         [0024]    As can be seen from  FIG. 2 , the shape of the cavity entrance  32  is such that the front edge  32   a  is generally straight and extends laterally across the width of the hand dryer  10 . However, the rear edge  32   b  has a shape which consists of two curved portions  33  which generally follow the shape of the backs of a pair of human hands as they are inserted downwardly into the cavity  30  through the cavity entrance  32 . The rear edge  32   b  of the cavity entrance  32  is substantially symmetrical about the centre line of the hand dryer  10 . The intention of the shaping and dimensioning of the front and rear edges  32   a ,  32   b  of the cavity entrance  32  is that, when a user&#39;s hands are inserted into the cavity  30  through the cavity entrance  32 , the distance from any point on the user&#39;s hands to the nearest slot-like opening is substantially uniform. 
         [0025]      FIGS. 5 to 7  show the inlet  44  of the hand dryer  10  in greater detail. The inlet  44  is provided in the lower face  19  of the casing  12 . The lower face  19  is downward-facing and so, in use, the inlet  44  faces the floor of a room in which the hand dryer is to be used. The inlet  44  comprises a plurality of inlet openings  80 . In this embodiment, four inlet openings  44  are provided. However, the number of inlet openings could be varied and it is envisaged that between three and six inlet openings will normally provide sufficient airflow whilst maintaining the structural integrity of the casing  12 . 
         [0026]    Each inlet opening  80  has a generally trapezoidal shape and is formed integrally with the casing  12  during manufacture. In the complete apparatus, each inlet opening  80  is closed at the rear side by the rear wall  16  of the casing  12  and extends toward the front wall  14  thereof. Each inlet opening  80  has a periphery  82  delimiting the opening  80 . A shield member  84  is provided adjacent each inlet opening  80 . Each shield member  84  is formed as a generally flat plate of generally trapezoidal shape similar to that of the corresponding inlet opening  80  and extends across the respective inlet opening  80  so as to overlie the opening  80  on the internal side thereof. The sides of the shield member  84  overlap the opposing long sides of the periphery  82  as can be seen from  FIGS. 6 and 7 . In this way, there is no direct line of sight from any point outside the casing  12  to the filter  46 . 
         [0027]    Each shield member  84  approaches the periphery  82  of the respective inlet opening  80  at the end thereof remote from the rear wall  16 . That part of the periphery  82  is therefore formed by one edge of the shield member  84 . A gap is formed between the shield member  84  and the periphery of the inlet opening  80 , the size of which gap increases towards the rear wall  16 . 
         [0028]    A vane  86  is carried by each of two of the four shield members  84  shown in  FIGS. 5 to 7 . The vane  86  is essentially planar and projects from the respective shield member  84  towards the lower face  19  of the casing  12 . The vane  86  is positioned centrally of the shield member  84  so that the vane  86  lies substantially midway between the opposing long sides of the periphery  82  of the inlet opening  80 . The vane  86  terminates in the plane of the inlet openings  80  (which is also the plane of the lower face  19  of the casing  12 ). Viewed from the side, the vanes  86  will have a generally triangular shape. Each vane  86  divides the space between the respective inlet opening  80  and the associated shield member  84  into two generally equal halves. 
         [0029]    A portion  88  of the lower face  19  of the casing  12  lies between each pair of adjacent inlet openings  80 . A vane  90 , similar to the vanes  86 , is carried by each of the casing portions  88 . Each vane  90  is substantially planar and extends towards the plane in which the shield members  84  lie. As before, each vane  90  terminates in the plane of the shield members and lies substantially midway between the edges of the shield members which lie closest to the vane  90 . 
         [0030]    The features of the inlet  44  described above are intended to be formed as a single unit with the shield members  84 , vanes  86  and vanes  90  being manufactured integrally with the front wall  14 , side walls  20 ,  22  and lower face  19  of the casing  12 . As can be seen from  FIG. 7 , the shield members  84  which are associated with the outermost inlet openings  80  can be supported by the outermost portions of the lower face  19  of the casing  12 . 
         [0031]    In the embodiment shown, four inlet openings  80  are provided. The innermost inlet openings have the same shape and configuration as one another whilst the outermost inlet openings differ therefrom. The inlet opening on the left hand side as shown in the drawings is similar to the innermost inlet openings, save that the corresponding shield member is supported along one of the long sides of the periphery and that no vane is provided on the shield member. The inlet opening on the right hand side as shown is similar to the left-hand inlet opening but is significantly narrower. 
         [0032]    As can be seen from  FIG. 7 , the arrangement described provides an inlet  44  which forces the incoming air to follow a convoluted path as it enters the drying apparatus  10 . The shape of the path defined between the vanes and the shield members includes two right-angled bends so that the air drawn into the dryer by the fan  40  is required to follow a “dog-leg” type path. There is thus no direct line of sight allowed from the outside of the casing  12  to any part of the interior of the casing  12  in which the filter, fan or motor might be housed. 
         [0033]    The hand dryer  10  described above operates in the following manner. When a user&#39;s hands are first inserted into the cavity  30  through the cavity entrance  32 , the sensors  64  detect the presence of the user&#39;s hands and send a signal to the motor to drive the fan  40 . The fan  40  is thus activated and air is drawn into the hand dryer  10  via the air inlet  44  at a rate of approximately 20 to 40 litres per second and preferably 25 to 27 litres per second, more preferably air is drawn into the hand dryer  10  at a rate of 31 to 35 litres per second. The incoming air passes through the inlet openings  80  between the vanes  86  and is deflected around the shield members before being passed to the filter  46 . 
         [0034]    The air passes through the filter  46  and along the fan inlet  42  to the fan  40 . The airflow leaving the fan  40  is divided into two separate airflows; one passing along the front air duct  50  to the slot-like opening  60  and the other passing along the rear air duct  52  to the slot-like opening  62 . 
         [0035]    The airflow is ejected from the slot-like openings  60 ,  62  in the form of very thin, stratified sheets of high velocity, high pressure air. As the airflows leave the slot-like openings  60 ,  62 , the air pressure is at least 15 kPa and preferably approximately 20 to 23 kPa. Furthermore, the speed of the airflow leaving the slot-like openings  60 ,  62  is at least 80 m/s and preferably at least 100 and 150 m/s, more preferably approximately 180 m/s. Because the size of the slot-like opening  62  located at the end of the rear duct  52  is greater than the size of the slot-like opening  60  located at the end of the front duct  50 , a larger volume of air is emitted from the duct  52  than from the duct  50 . This provides a greater mass of air for drying the backs of the user&#39;s hands which is advantageous. 
         [0036]    The two thin sheets of stratified, high velocity, high pressure air are directed towards the surfaces of the user&#39;s hands which, during use, are inserted fully into the cavity  30  and are subsequently withdrawn from the cavity  30  via the cavity entrance  32 . As the user&#39;s hands pass into and out of the cavity  30 , the sheets of air blow any existing water off the user&#39;s hands. This is achieved reliably and effectively because of the high momentum of the air leaving the slot-like openings  60 ,  62  and because the airflow is evenly distributed along the length of each slot-like opening  60 ,  62 . 
         [0037]    Each stratified sheet of air is directed towards the wall of the cavity  30  which is remote from the slot-like opening through which the respective sheet of air is emitted. Because the slot-like openings  60 ,  62  are also inclined towards the lowermost end of the cavity  30 , the emitted airflows are directed into the cavity  30 . This reduces the risk of turbulent air movement being felt by the user outside the casing, eg in the user&#39;s face. 
         [0038]    It is envisaged that it will take only a small number of “passes” of the hand dryer described above to dry a user&#39;s hands to a satisfactory degree. (By “pass”, we mean a single insertion of the hands into the cavity and subsequent removal therefrom at a speed which is not unacceptable to an average user. We envisage that a single pass will have a duration of no more than 3 seconds.) The momentum achieved by the airflows is sufficient to remove the majority of water found on the surface of the user&#39;s hands after washing during a single pass. 
         [0039]    The water removed by the airflows is collected inside the cavity  30 . Each airflow will rapidly lose its momentum once it has passed the user&#39;s hands and the water droplets will fall to the lower end of the cavity  30  under the forces of gravity whilst the air exits the cavity  30  either through the cavity entrance  32  or via the open sides of the cavity  30 . The water, however, is collected by the drain  38  and passed to a reservoir (not shown) where it is collected for disposal. The reservoir can be emptied manually if desired. Alternatively, the hand dryer  10  can incorporate some form of water dispersal system including, for example, a heater for evaporating the collected water into the atmosphere. The means by which the collected water is dispersed does not form part of the present invention. 
         [0040]    In an alternative embodiment, the slot-like openings  60   a ,  62   a  can be arranged so that the sheets of air which are emitted therefrom are directed generally along planes which are substantially parallel to one another. This minimises the amount of turbulent flow present inside the cavity  30  whilst the drying apparatus is in use. 
         [0041]    The invention is not intended to be limited to the precise detail of the embodiment described above. Modifications and variations to the detail which do not alter the scope of the invention will be apparent to a skilled reader. For example, the shape of the inlet openings and the shield members can be varied without departing from the essence of the present invention.