Abstract:
A drying apparatus has a casing, a cavity formed in the casing for receiving an object, a fan located in the casing and creating an airflow, and at least one slot-like opening communicating with the fan and arranged in the casing so as to direct an airflow transversely across the cavity. The slot-like opening is formed between opposing walls so that one of the walls terminates substantially flush with the casing and the other wall protrudes beyond the casing. The slot-like opening may be formed between an upper wall and a lower wall, the lower wall may terminate substantially flush with the casing and the upper wall protrudes beyond the casing, reducing the effect of the air causing the user&#39;s hands to be pulled or sucked towards the slot-like openings but eliminating any protrusion of the walls of the slot-like opening on one side.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a national stage application under 35 USC 371 of International Application No. PCT/GB2006/002135, filed Jun. 12, 2006, which claims the priority of United Kingdom Application No. 0515741.7, filed Jul. 30, 2005, the contents of both of which prior applications are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to drying apparatus which makes use of a narrow jet of high velocity, high pressure air to dry an object, including part of the human body. Particularly, but not exclusively, the invention relates to a hand dryer in which the air jet is emitted through a slot-like opening in the casing of the hand dryer. 
       BACKGROUND OF THE INVENTION 
       [0003]    The use of air jets to dry hands is well known. Examples of hand dryers which emit at least one air jet through a slot-like opening are shown in GB 2249026A, JP 2002-034835A and JP 2002306370A. The walls of the slot-like openings shown in some of these prior art documents project beyond the walls of the casings in which the slot-like openings are formed. This reduces the likelihood of the user&#39;s hands being sucked towards the wall of the casing while the hand dryer is in use. However, the protrusion of the walls of the slot-like openings also presents a hazard in that the user&#39;s hands may be scratched on the walls, or articles such as watches, bracelets and the like may become caught or snagged thereon. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the invention to provide drying apparatus which, in use, is comfortable for the user to use and which reduces or eliminates any risk of objects becoming caught or snagged during use. 
         [0005]    The invention provides drying apparatus having a casing, a cavity formed in the casing for receiving an object, a fan located in the casing and capable of creating an airflow, and at least one slot-like opening communicating with the fan and arranged in the casing so as to direct an airflow transversely across the cavity, the slot-like opening being formed between opposing walls, wherein one of the walls terminates substantially flush with the casing and the other wall protrudes beyond the casing. 
         [0006]    Preferably, the slot-like opening is formed between an upper wall and a lower wall and, more preferably, the lower wall terminates substantially flush with the casing and the upper wall protrudes beyond the casing. 
         [0007]    This arrangement has been found still to reduce the effect of the air causing the user&#39;s hands to be pulled or sucked towards the slot-like openings but has the added advantage of eliminating any protrusion of the walls of the slot-like opening on one side thereof. It is particularly useful to eliminate the protrusion of the walls on the lower side of the slot-like opening as this helps to avoid clothing, watches, bracelets and the like becoming caught or snagged on what would otherwise be an overhanging lip as the hands are withdrawn from the cavity. 
         [0008]    In a preferred embodiment, the upper wall protrudes beyond the casing to a distance of substantially 5 mm. This distance has been found to be sufficient to avoid the user&#39;s hands being pulled towards the slot-like openings when only one wall protrudes beyond the casing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    An embodiment of the invention in the form of a hand dryer will now be described with reference to the accompanying drawings, in which: 
           [0010]      FIG. 1  is a side view of a hand dryer according to the invention; 
           [0011]      FIG. 2  is a perspective view of the hand dryer of  FIG. 1 ; 
           [0012]      FIG. 3  is a side sectional view of the hand dryer of  FIG. 1 ; 
           [0013]      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 ; 
           [0014]      FIG. 5  is a schematic sectional side view, shown on a further enlarged scale, of the slot-like opening located in the front wall of the cavity of the hand dryer of  FIG. 1 ; and; 
           [0015]      FIG. 6  is a schematic sectional side view, shown on the same further enlarged scale, of the slot-like opening located in the rear wall of the cavity of the hand dryer of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    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  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 . 
         [0017]    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. 
         [0018]    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 . 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 . 
         [0019]    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 . 
         [0020]      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 . Even greater detail can be seen in  FIGS. 5 and 6 .  FIG. 5  shows that the slot-like opening  60  has a width of W 1  and  FIG. 6  shows that the slot-like opening  62  has a width of W 2 . The width W 1  of the slot-like opening  60  is smaller than the width W 2  of the slot-like opening  62 . The width W 1  is 0.3 mm and the width W 2  is 0.4 mm. 
         [0021]    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 . 
         [0022]    As can be seen from  FIGS. 3 and 4 , the upper walls  54   a ,  56   a  of the ducts  50 ,  52  project slightly beyond the surface of the front and rear walls  34 ,  36  of the cavity  30  whilst the lower walls  54   b ,  56   b  terminate substantially flush with the front and rear walls  34 ,  36  of the cavity  30 . The distance by which the upper walls  54   a ,  56   a  project is selected to be substantially 5 mm. The inward projection of the upper walls  54   a ,  56   a  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. However, the elimination of any protrusion of the lower walls  54   b ,  56   b  beyond the front and rear walls  34 ,  36  means that a smooth surface is presented below the slot-like openings  60 ,  62 . 
         [0023]    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. 
         [0024]    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 at a rate of least 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 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 . 
         [0025]    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 or 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. 
         [0026]    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 . 
         [0027]    The protrusion of the upper walls  54   a ,  56   a  beyond the front and rear walls  34 ,  36  of the cavity reduces the risk of the user&#39;s hands being sucked towards either of the slot-like openings  60 ,  62  which provides more comfort for the user. As the user&#39;s hands are withdrawn from the cavity, a smooth surface is presented to the hands which does not include any overhanging or sharp projections. Thus, even if the user&#39;s hands are inadvertently drawn or moved towards the slot-like openings, there is no risk of the user&#39;s hands becoming scratched or grazed, nor of any items such as clothing, watches or bracelets becoming caught or snagged on the slot-like openings. 
         [0028]    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. 
         [0029]    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. 
         [0030]    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. 
         [0031]    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. 
         [0032]    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 cavity  30  and its entrance  32  may be altered without departing from the essence of the present invention.