Patent Publication Number: US-7900372-B2

Title: Clothes dryer with louvre cover

Description:
FIELD OF THE INVENTION 
     The present invention relates to a clothes dryer and, more particularly, relates to one or more covers placed over air entry louvres to restrict the flow of ignited particles, and other debris as a result of a fire, from escaping from the dyer through the louvres should a fire develop in the dryer cabinet. 
     BACKGROUND OF THE INVENTION 
     In a clothes dryer air is typically circulated across clothing contained in a rotating dryer drum. The air is heated prior to entry into the drum by means of electrically energized heating elements or by a gas burner contained in a heating assembly. Air is either drawn, or blown, through the drum by a fan that moves the air out of the drum across a lint filter and through exhaust venting out of the dryer. Typically, the rear wall of the dryer is provided with louvres comprising horizontal extending openings having fixed sloping fins that allow ambient air to enter the dryer cabinet and pass through the heater assembly. The ambient air is drawn through the louvres into the cabinet due to the negative pressure created in the dryer cabinet by the air moving out of the cabinet via the exhaust venting. 
     When the dryer is subjected to recent and more stringent fire testing, sparks of ignited particles of cheese cloth, representing dust or lint, rise and fall within the dryer cabinet and in some instances escape from the dryer cabinet through the louvre. Accordingly, there is a need to develop an air flow entry for a dryer that permits ambient air to flow into the dryer during normal dryer operation and restricts the flow of ignited particles and other debris escaping from the dryer cabinet so as to help contain a fire in the cabinet should one develop. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention relates to a clothes dryer and, more particularly, relates to one or more covers placed over air entry louvres to restrict the flow of ignited particles and other debris from escaping from the dyer through the louvres should a fire develop in the dryer cabinet. 
     In accordance with one embodiment of the present invention, a clothes dryer comprises a cabinet having a wall and a louvre located in the wall to allow ambient air to enter the cabinet. The clothes dryer comprises a cover mounted inside the cabinet and mounted to the wall. The cover extends over the louvre to define an air flow channel that permits air to flow into the cabinet through the louvre and along the air flow channel while restricting flow of ignited particles and debris from exiting through the louvre. 
     In accordance with another embodiment, the cover overlays the louvre and is spaced therefrom. The cover extends along the louvre to define an air flow channel between the cover and the wall where the airflow channel has an at least one opening between the wall and an end portion of the cover to permit air to flow into the cabinet through the louvre, along the air flow channel and out the at least one opening while restricting flow of ignited particles and debris from exiting through the louvre. 
     By having the cover spaced from the louvre, an airflow channel is defined between the cover and rear wall that extends along the length of the louvre. While this airflow channel forms a restriction to air flowing into the dryer cabinet, this restriction is inconsequential due to the negative pressure induced in the dryer during dryer operation by the blower fan. The blower fan draws ambient air in through the louvre and along the airflow channel into the dryer cabinet space while at the same time pushing heated air from the dryer drum out the dryer exhaust vent. The advantage associated with the use of the cover is that it helps to contain a fire within the dryer should one occur. Any particles which are ignited in the dryer, or other debris as a result of a fire, have a tendency to rise and fall within the dryer cabinet. The cover extending over the louvres restrict flow of rising and falling particles from exiting directly out of the louvre without having to first enter into the airflow channel. 
     It should be understood that one or more covers preferably extends at least along the entire length of the louvre to form the air flow channel along the length of the louvre and perhaps beyond. This air flow channel is open at the ends of the cover to permit air flow into the dryer. 
     In an embodiment of the present invention a plurality of louvres are located in a rear wall of the cabinet. Each louvre has a cover that defines an airflow channel extending along the corresponding louvre. 
     In one embodiment the cover may comprise a bracket that has side walls that extend from the wall of the cabinet to form the airflow channel. In a preferred embodiment the cover has an additional end wall so that it has a u-shaped configuration where the end wall extends between the side walls of the bracket. The side walls further each comprise a flange that lies flush with and may be mounted to the wall of the cabinet. The cover bracket has opposing open ends through which air entering through the louvre moves along the air flow channel and passes through the open ends into the cabinet. It should be understood that while the preferred embodiment is directed to a bracket having a square u-shaped cross-sectional configuration, alternative suitable shapes may be employed such as, for example, a triangular V-shaped cross-sectional shape, a rounded u-shaped cross-sectional shape, or a semi-circular cross-sectional shape. Each of these embodiments provides the airflow channel that extends along the length of the louvre. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more thorough understanding of the nature and objects of the present invention reference may be had, by way of example, to the accompanying diagrammatic drawings in which: 
         FIG. 1  is a perspective view of an exemplary clothes dryer that may benefit from the present invention; 
         FIG. 2  is a side sectional view of an exemplary clothes dryer that may benefit from the present invention; 
         FIG. 3  is an interior perspective of the exemplary clothes dryer showing the rear wall of the clothes dryer cabinet with most of the internal components removed; 
         FIG. 4  is a closer perspective view of the rear wall of the dryer cabinet from inside the dryer cabinet; 
         FIG. 5  is an enlarged partial perspective sectional view of the covers of the present invention; and, 
         FIGS. 6A , to  6 C show cross-sectional shapes of alternative embodiments for the cover. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 and 2  show perspective and side sectional views of an exemplary clothes dryer  10  that may benefit from the present invention. The clothes dryer  10  includes a cabinet or a main housing  12  having a front wall  14 , a rear wall  16 , a pair of side walls  18  and  20  spaced apart from each other by the front and rear walls, and a top cover  24 . Within the housing  12  is a drum or container  26  mounted for rotation around a substantially horizontal axis. A motor  44  rotates the drum  26  about the horizontal axis through, for example, a pulley  40  and a belt  42 . The drum  26  is generally cylindrical in shape, has an outer cylindrical wall  28 , and has an open end  27  that typically comprises a metal ring  29  attached by welding to the drum  26  for reducing the diameter of the opening of the drum  26  to match a front bulkhead wall or front bearing  30 . The bearing  30  further defines an opening  32  into the drum  26 . Clothing articles and other fabrics are loaded into the drum  26  through the opening  32 . A plurality of tumbling ribs (not shown) are provided within the drum  26  to lift the articles and then allow them to tumble back to the bottom of the drum as the drum rotates. The drum  26  includes a rear wall  34  rotatably supported within the main housing  12  by bearing  35 . The rear wall  34  includes a plurality of holes (not shown) that receive hot air that has been heated by a heater such as electrical heating elements (not shown) in the heater housing  22 . The heater housing  22  receives ambient air via an inlet  36 . Although the exemplary clothes dryer  10  shown in  FIG. 1  is an electric dryer, it could just as well be a gas dryer having a gas burner. 
     Heated air is drawn from the drum  26  by a blower fan  48  which is also driven by a second motor  49  in the embodiment shown. In an alternative embodiment, motor  44  could be used to drive blower fan  48 . The air passes through a grill  45  and screen filter  46 . Grill  45  keeps clothing articles tumbling in the drum  26  from contacting the filter  46  and touching the lint trapped by the filter  46  within the trap duct  50 . As the air passes through the screen filter  46 , it flows through lower duct portion  51  and is drawn by blower fan  48  attached to motor  49  out of the clothes dryer through an exhaust duct  52 . In this embodiment, the drum  26  is in air flow communication with the trap duct  50  whose lower duct portion  51  has an outlet that is in air flow communication with the blower fan  48  and the exhaust duct  52 . The exhaust duct  52  passes through the rear wall  16  and is usually connected to suitable venting (not shown) that provides an exhaust path for the dryer heated air to leave the room where the dryer  10  is located. 
     It should be understood that the blower fan  48  creates a negative type pressure within the dryer cabinet by its operation during normal dryer use. By negative pressure it is meant that because the blower fan  48  is forcing air out of the exhaust duct  52  it is creating a negative pressure in the dryer cabinet which draws air from the ambient outside of the dryer into the dryer cabinet for circulation through the dryer drum  26 . In order to have ambient air enter the cabinet  12  the dryer, as shown in  FIG. 2 , dryer  10  is provided with one or more louvres  70  and covers  72  which will be described in more detail hereinafter. 
     After the clothing articles have been dried, they may be removed from the drum  26  via the opening  32 . Opening  32  is shown closed by a window or port-hole like door  60 . Door  60  has a handle  62  for pivotally opening the door about hinge  64 . 
     The dryer  10  is shown to have a control wall  54  with touch and or dial controls  56  that permit the user to control operation of dryer  10 . 
     As shown in  FIGS. 3 to 5 , louvres  70  extend horizontally along the rear wall  16  and provide opening  74  in the rear wall through which ambient air may enter as shown by the airflow arrows  76  in  FIG. 4 . The airflow arrow  76  shows ambient air entering the dryer during normal dryer operation as a result of the operation of the blower fan  48  ( FIG. 2 ). 
     As shown in  FIGS. 3 to 5 , covers  72  cover the louvres  70  by overlaying the louvres  70  in spaced relation therefrom. The covers  72  extend along the horizontal length of the louvres  70 . In one embodiment, one cover  72  may cover more than one louvre or alternatively, one or more covers  72  may cover one louvre  70 . The purpose of the cover  72  is to restrict flow of ignited particles  80  ( FIG. 4 ) and other debris from leaving the dryer cabinet should a fire develop in the dryer. The airflow pattern of the rising ignited particles  80  is generally shown by arrows  82  to be generally upward. Such particles can also fall. However it should be understood that any changes in the current of the airflow may potentially result in the particles  82  moving through the openings  74  of the louvres  70  and exiting the dryer cabinet if the covers  72  are not present. Hence the covers guard against and restrict flow of particles  80 , and other debris rising and falling within the cabinet, from exiting the cabinet  12  through the louvre  70 . 
     In the embodiment shown, the covers  72  have a generally u-shaped cross-section provided by an end wall  90  with two side walls  92  that space the cover end wall  90  inwardly into the cabinet  12  away from the rear wall  16  of the dryer cabinet  12 . As a result, between the covers  72  and an inner side of the rear wall  16 , there is defined an airflow channel  100  which extends along the length of the louvre  70 . The side walls  92  further have flanges  94  which lie flush with and are mounted to the cabinet rear wall  16  by suitable means such as screws (not shown) which pass through openings  96  in the flange  94  and into the rear wall  16  of the cabinet  12 . The upper flanges  94  are elongate and co-extend, or at least partially co-extend, with the upper side wall  92  whereas the lower flange  94  is a button-like flange that extends out from the lower side wall  92  of the cover  72 . The cover  72  preferably is made from steel, similar to the material for the rear wall  16  of the dryer  10 . Alternatively, the cover  72  may comprise any suitable material that is resistant to fire. 
     The cover  72  effectively extends at least along the horizontal length of the louvre to define a horizontally extending airflow channel  100  that allows the ambient air  76  to flow out the horizontally opposed open ends portions  102 , defined between an end portion of the cover  72  and the wall  16  of the cabinet, during normal dryer operation. The cover also guards against or restricts the flow of particles  80  from escaping out of the cabinet through the openings  74  in the louvres  70  due to any shifts in air current or rising and falling of the particles or debris. Clearly advantage is found with the covers  72  as they reduce the risk of fires spreading from the dryer cabinet by impeding the flow of ignited particles, and other debris, from passing through opening  74  in louvre  70 . 
     Referring to  FIGS. 3 ,  4  and  5 , is can also be seen that the rear wall  16  of the cabinet is shown to include louvre  71  that is uncovered. Louvre  71  remains uncovered because, in the fully assembled dryer, the rear wall of the heater housing  22  (see  FIG. 2 ), or diffuser wall, is very close to the rear wall  16  of the dryer cabinet and covers the louvre  71  whereby debris and ignited particles are restricted from flowing between the heater housing  22  and the rear wall  16 . 
     Referring to  FIGS. 6A to 6C , the covers  70  are shown respectively to have a triangular V-shaped cross-sectional shape, a semi-circular cross-sectional shape, and a rounded u-shaped cross-sectional shape. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the scope of the present invention as disclosed herein.