Patent Abstract:
A clothes dryer cabinet has a rear wall with a wire entry opening through which wiring enters into the dryer cabinet. A fuse supporting block is mounted closely adjacent to the wire entry opening and supports fuses which are connected directly to the wiring entering through the wire opening so as to limit or minimize the length of wiring contained in the dryer drum that is not protected by the fuses. This safety feature reduces the chance of fires occurring in the dryer as a result of arcing between wires due to mishandling of the wires, malmanufacturing of the wires or a fire occurring in the dryer.

Full Description:
FIELD OF THE INVENTION 
     The present invention relates to a clothes dryer and, more particularly, to the placement of fuses in the clothes dryer cabinet to reduce the risk of fire occurring in the dryer cabinet or outside the cabinet due to shorting of the live wire lines in the dryer cabinet with one another, with the dryer cabinet, or with components inside the dryer cabinet. 
     BACKGROUND OF THE INVENTION 
     In domestic clothes dryers there has been a concern with respect to the build up of lint in the dryer or the ducting exiting the dryer, which build up of lint may result in the possibility of a fire in the dryer. As lint builds up in the dryer it creates a restriction on the airflow through the dryer. U.S. Pat. No. 6,671,977 issued to Beaumount discloses a safety system located outside of the dryer that measures the airflow in the exhaust vent and disconnects power to the household dryer female plug receptacle in the event that the airflow drops below a predetermined value. 
     U.S. Pat. No. 6,655,047 issued to Miller, II discloses a fire arrester for use with a clothes dryer that has a fire detector in a dryer vent externally of the dryer that detects fires starting in the dryer and disconnects electricity to the dryer while at the same time releasing an extinguishing agent into the dryer to suppress a fire. Neither of these two U.S. patents teaches the use of fuses in the dryer to disconnect power to the dryer. 
     U.S. Pat. No. 5,315,765 issued to Holst discloses a circuitry for a high efficiency microwave dryer wherein the live wire lines each has a fuse connected in circuit therewith. A third fuse is connected in circuit with a DC power supply. This patent teaches these fuses being current limiting fuses. There is no teaching of the physical location of these fuses in the dryer cabinet. U.S. Pat. No. 4,663,861 also discloses a fuse in dryer circuitry for disconnecting power to the dryer control circuit. There is no teaching in this patent of the physical location of the fuses in the dryer cabinet. Further, neither of these two US patents discloses the purpose of these fuses other than to be current limiting fuses. 
     As a result of testing done on domestic clothes dryers, it has been determined that electrical arcing between wires in the cabinet of the dryer can cause fire on the wire coatings of the wire, can spread fire to other areas in the dryer or ignite a cheese cloth draped over the dryer cabinet where the cheese cloth represents clothing left on top of the dryer by a user. Testing has shown that this arcing has caused cheese cloth, representing dust or lint trapped in the dryer or other items placed on or beside the dryer, to catch fire. The mere use of fuses in the wiring circuitry of the power lines may not be sufficient to reduce the risk of fire due to arcing between live wires. Further, the use of power disconnect devices other than fuses may be too slow or not sufficiently sensitive to disconnect power from the dryer when initial arcing occurs between wires. Also, power disconnect devices may not protect against arcing due to fires being random and the power disconnect device not reacting to potential causes of the fire resulting in a fire being produced in the dryer cabinet or on the outside of the cabinet. Consequently there is a need in domestic clothes dryers to provide for power disconnection to the dryer electrical load in the cabinet such that the wiring in the cabinet is a reduced safety hazard. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention relates to a clothes dryer and, more particularly, to the placement of fuses in the clothes dryer cabinet to reduce the risk of fire occurring in the dryer cabinet, or outside the dryer cabinet, due to shorting of the live wire lines themselves in the dryer cabinet, with the cabinet, or components inside the cabinet. The placement of the fuses closely adjacent to the opening where the wiring enters the clothes dryers allows the fuses to be wired into the circuit in series with each of the live power lines and thereby limit or minimize the length or amount of wiring in the dryer cabinet that is not protected by the fuse. Hence the risk is diminished of a fire starting due to arcing between wires, between the wires and components in the cabinet, or between the wires and the cabinet as a result of mishandling of the wiring, malmanufacturing of the wires, or due to fire that melts or burns wire insulation and causes electrical shorting that may ignite clothing that drapes the dryer cabinet. 
     It is important to disconnect power to the clothes dryer circuitry in the event of a fire in the base of the cabinet or in the drum of the dryer thus preventing any further shorting of the wires so as to diminishes the chances of a fire spreading outside of the dryer cabinet. Hence it is advantageous to have as much wire protected as possible in the cabinet by the fuses as this reduces the risk of any fire initiating in the dryer cabinet as a result of the wiring in the cabinet arcing. 
     In accordance with one embodiment of the present invention, there is provided a clothes dryer having an electrical load, comprising a cabinet having a wall. A power cord is electrically connected to the wall of the cabinet. The power cord has a neutral wire line and at least one entry live wire line. The neutral line is connected in electrical circuit with the electrical load. The wall has a wiring entry opening through which the neutral wire line and the at least one entry live wire line pass into, and extend within, the cabinet. The electrical load is further connected in electrical circuit with at least one load live wire line extending within the cabinet. A fuse for each entry live wire line is connected in electrical circuit between a corresponding entry live wire line and a corresponding load live wire line for disconnecting power to the load live wire line and the electrical load. The fuse is located inside the cabinet closely adjacent to the wiring entry opening so as to limit length of the at least one entry live wire line within the cabinet. 
     In accordance with another embodiment of the invention there is provided a clothes dryer having an electrical load, comprising a cabinet having a wall. A power cord is electrically connected to a terminal block mounted on the wall outside of the cabinet. The power cord has a cord neutral wire line and two cord live wire lines respectively connected at the terminal block to a dryer neutral wire line and corresponding ones of two dryer entry live wire lines. The electrical load is connected in electrical circuit with the dryer neutral wire line and two load live wire lines extending only within the cabinet. The wall has a wiring entry opening through which the dryer neutral wire line and the two dryer entry live wire lines pass into the cabinet from the block. Two fuses are each connected in electrical circuit between a corresponding one of the dryer entry live wire lines and a corresponding one of the load live wire lines for disconnecting power to the corresponding one load live wire line and the electrical load. The fuses are located inside the cabinet closely adjacent to the wiring entry opening so as to limit length of the dryer entry live wire lines within the cabinet. 
    
    
     
       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 the rotating drum removed; 
         FIG. 4  is a partial exterior view of the rear wall showing the connection of the power cord to an exemplary terminal block for an exemplary electric clothes dryer; 
         FIG. 5  is an electrical schematic diagram for an exemplary clothes dryer heated by one or more electrical heating elements; and, 
         FIG. 6  is an electrical schematic diagram for and exemplary clothes dryer heated by a gas heater. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to a clothes dryer and in particular to the placement of fuses in the clothes dryer cabinet to reduce the risk of fire occurring in the dryer cabinet due to shorting of the live wire lines in the dryer cabinet. 
     Referring to  FIGS. 1 to 3 , an exemplary clothes dryer  10  that may benefit from the present invention is shown. 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, a floor  21  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 drum rear wall  34  rotatably supported within the main housing  12  by bearing  35 . The drum rear wall  34  includes a plurality of holes (not shown) that receive hot air that has been heated by a heater comprising electrical heating elements  64  located in heater housing  22 . The heater housing  22  receives ambient air passing through an inlet or louvres  36  and into the heater housing around circular flange  66  of the heater housing  22 . 
     Although the exemplary clothes dryer  10  shown in  FIG. 1  is an electric dryer having electrical heating elements  64  that warm the ambient air, it should be understood that the dryer may be a gas dryer having a gas burner for heating ambient air entering the dryer. The gas burner may be located below the drum  26  and have ducting extending from the gas burner up to the drum rear wall  34 . 
     Air heated by the heater is drawn into and 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  may be used to drive blower fan  48 . Air is drawn by the blower fan  48  from the heater housing  22 , into, through and out of the drum  26 , 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 blown by blower wheel  48  attached to motor  49  out of the clothes dryer  10  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 wheel  48  and the exhaust duct  52 . The exhaust duct  52  passes through the rear panel  16  and is usually connected to suitable venting (not shown) that vents the air outdoors. 
     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 panel  54  with touch and or dial controls  56  that permit the user to control operation of dryer  10 . 
     Referring to  FIGS. 3 ,  4  and  5  the wiring circuitry for clothes dryer  10  is shown. Power is supplied to the dryer in  FIG. 4  through a power cord  68 , the power cord  68  has two live power wire lines  70  and  72 , a neutral wire line  74  and a ground wire  76 . Ground wire  76  is shown connected by screw  78  to the rear wall  16  of the clothes dryer. The wire lines  70 ,  72 ,  74  and  76  of the power cord  68  are rated for 120/240 volts and 30 amps. The power cord  68  is connected to the dryer rear wall  16  through a strain relief bracket  80 . The live wire lines  70  and  72  as well as the neutral wire line  74  are connected by screws  82  to separate connection terminals in terminal block  84  of the terminal block assembly  86 . A cover  88  is fastened by screw  89  to the rear wall  16  to cover the terminal block assembly  86 . The terminal block  84  is shown mounted to the outside of the rear wall  16 . 
     Referring to  FIGS. 3 and 4 , a dryer neutral wire line  90  and two cabinet live wire lines  92  and  94  pass through a wiring entry opening  100  located in the rear panel  16  of the dryer  10 . Wires  90 ,  92  and  94  are shown in  FIG. 4  entering the dryer cabinet  12  through the opening  100  and are shown in  FIG. 3  emerging from the opening  100  into the interior of the dryer cabinet  12 . The dryer entry live wires  92  and  94  are respectively connected through fuses  104  and  106  with respective load live wire lines  96  and  98 . Load live wire lines  96  and  98  together with neutral line  90  are connected in wiring harness  108  to provide power to various loads within the clothes dryer cabinet including for example motor  44  and heating elements  64  of heater housing  22 . It should be understood that the wiring harness  108  will also provide power to motor  42  and to a power supply (not shown) for the electronic components for the clothes dryer  10 . 
     Referring to  FIG. 5 , the distribution of the power to the loads  44 ,  49 ,  64  and  110  in the dryer drum is shown. Power line L 1  has fuse  104  between dryer load live wire line  98  and dryer entry wire line  92  to provide power to the drum motor  44  and the blower motor  49 . Power from the second power line L 2  is by dryer entry power live wire line  94 , fuse  106 , and load power live wire line  96  to the electrical heating element  64  and the electronic power supply  110 . In the event of shorting or arcing caused by the wire lines  96 ,  98 ; fuses  106 ,  104  open or blow disconnecting the load wires from the power. 
     As can be seen in  FIG. 3 , the placement of the fuses  104  and  106  on the fuse terminal block or supporting block  102  is closely adjacent to the entry opening  100  for the wiring. This limits the length of the wires  92  and  94  to extend a considerably short distance within the dryer cabinet. As a result, this is the only portion of the live wires in the cabinet that may be considered to be unprotected by the fuses. Accordingly the other live wiring associated with live load wire lines  96  and  98  are protected by the fuses  104  and  106  blowing to disconnect power to the live load wiring  96  and/or  98  in the event of any arcing or deterioration in the wiring thereby reducing the risk of a potential fire in the dryer cabinet or outside the dryer cabinet. 
     The wiring circuitry shown in  FIGS. 3 and 4  is for two power lines to the electric dryer and the fuses are each 30 amp fuses referred to as FLM fuses. A fuse suitable for the embodiment of the present invention of  FIGS. 3 and 4  is a 30 amp fuse manufactured by LITTEL FUSE of Illinois, USA under part number L7L12F. 
     It should be understood that for a gas dryer, the amount of power to the dryer is reduced since the heating is achieved by combustion of natural gas or propane gas, and not by electrical heating elements. As a result, typically wiring for this arrangement comprises one power line and one neutral line entering into the dryer drum and rated at 120V and 15 Amps. A power cord connected to the dryer includes a power line, a neutral line and a grounding wire line. The grounding wire is grounded to the chassis or cabinet  12  of the clothes dryer  10 . A block is used similar to that shown in  FIG. 4 , or alternatively, the power cord is connected directly through a strain relief bracket to the dryer so that the live wire line and the neutral wire line of the power cord pass directly through a wire entry opening into the clothes dryer cabinet. The fuse is located closely adjacent to the entry opening so as to minimize the length of unprotected live wire line of the power cord within the dryer cabinet. A schematic representation of the wiring diagram or such a system is shown in  FIG. 6  wherein the entry live wire line  116  and the neutral wire line  114  are provided for supplying power to the blower motor  49 , the drum motor  44 , the gas burner  120 , and the electronic power supply  110 . Fuse  118  is located in the circuit to disconnect power to the load live wire line  130  and the load  49 ,  44 ,  120 , and  110 . 
     The fuse  118  is located closely adjacent to the entry opening through which the power lines entered into the dryer cabinet similar to the arrangement shown in  FIG. 3 , save for one fuse instead of two, so as to minimize the length of the live wire line within the cabinet that is not protected by the fuse  118 . In this embodiment for a gas dryer, one 15 amp fuse may be used such as a CCMR fuse. Such a fuse is available by LITTEL FUSE under part number L8B22F. 
     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.

Technology Classification (CPC): 3