Patent Publication Number: US-7904981-B2

Title: Water supply control for a steam generator of a fabric treatment appliance

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application constitutes a divisional application of U.S. patent application Ser. No. 11/464,509, allowed, entitled “WATER SUPPLY CONTROL FOR A STEAM GENERATOR OF A FABRIC TREATMENT APPLIANCE” filed Aug. 15, 2006. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to methods and structures for controlling supply of water to a steam generator of a fabric treatment appliance. 
     2. Description of the Related Art 
     Some fabric treatment appliances, such as a washing machine, a clothes dryer, and a fabric refreshing or revitalizing machine, utilize steam generators for various reasons. The steam from the steam generator can be used to, for example, heat water, heat a load of fabric items and any water absorbed by the fabric items, dewrinkle fabric items, remove odors from fabric items, etc. 
     Typically, the steam generator receives water from a household water supply. It is important that the steam generator has a sufficient amount of water to achieve a desired steam generation rate and to prevent damage to the steam generator. Prior art fabric appliances incorporate pressure sensors and electrical conduction sensors in the steam generator to determine the level of water in the steam generator. Based on the output of the sensor, water can be supplied to the steam generator to maintain a desired water level. While these pressure and electrical conduction sensors provide a couple ways of controlling the supply of water to the steam generator, other possibly more economical, reliable, and elegant methods and structures for controlling the water supply to a steam generator of a fabric treatment appliance are desirable. 
     SUMMARY OF THE INVENTION 
     A fabric treatment appliance according to one embodiment of the invention comprises at least one of a tub and drum defining a fabric treatment chamber; a steam generator having a steam generation chamber and configured to supply steam to the fabric treatment chamber; a conduit fluidly coupling a household water supply to the steam generation chamber; and a flow controller fluidly coupled to the conduit and configured to effect a flow of water through the conduit at a restricted flow rate less than a flow rate of the household water supply for a predetermined time based on the restricted flow rate to deliver a predetermined volume of water to the steam generation chamber. 
     The flow controller can comprise a restrictor configured to restrict the flow of water through the conduit to the restricted flow rate. The flow controller can further comprise a valve operable to turn the flow of water through the conduit on and off. The restrictor and the valve can each have a corresponding flow rate, and the restricted flow rate used to determine the predetermined time can be the smaller of the flow rates. The restrictor can positioned upstream from the valve. Alternatively, the restrictor can be positioned downstream from the valve. Optionally, the restrictor can be integrated with the valve. The restrictor can comprise a rubber flow restrictor. 
     The flow controller can comprise a proportional valve operable to turn the flow of water through the conduit on and off and to restrict the flow of water through the conduit to the restricted flow rate. 
     The predetermined volume of water can correspond to a volume of the steam generation chamber. 
     The steam generator can be an in-line steam generator. 
     A method according to one embodiment of the invention of operating a fabric treatment appliance having a fabric treatment chamber and a steam generator for supplying steam to the fabric treatment chamber comprises restricting a flow rate of water to the steam generator from a water supply to less than a flow rate of the water supply; supplying a predetermined volume of water to the steam generator by supplying water from the water supply to the steam generator for a predetermined time based on the restricted flow rate; and generating steam in the steam generator from the supplied water. 
     The method can further comprise resupplying water to the steam generator. The resupplying of the water can comprise supplying water to the steam generator based on a steam generation rate of the steam generator. The resupplying of the water can comprise maintaining the predetermined volume of water. The resupplying of the water can comprise supplying a second predetermined volume of water for a second predetermined time. The second predetermined volume of water can be less than the initial predetermined volume of water, and the second predetermined time can be less than the initial predetermined time. 
     The predetermined volume of water can correspond to an internal volume of the steam generator. 
     A method according to another embodiment of the invention of operating a fabric treatment appliance having a fabric treatment chamber and a steam generator for supplying steam to the fabric treatment chamber comprises supplying water to the steam generator; determining the volume of water supplied; stopping the supplying of water once a predetermined volume of water has been supplied to the steam generator; and generating steam in the steam generator from the supplied water. 
     The determining of the volume of water can comprise sensing a flow of water to the steam generator. The sensing of the flow can comprise measuring a flow rate of water to the steam generator. The flow rate can be a volumetric flow rate. The determining of the volume of water can comprise calculating the volume of water from the volumetric flow rate and a time the water is supplied. The sensing of the flow can comprise measuring a volume of water supplied to the steam generator. 
     The method can further comprise resupplying water to the steam generator. The resupplying of the water can comprise supplying water to the steam generator based on a steam generation rate of the steam generator. The resupplying of the water can comprise maintaining the predetermined volume of water. 
     The predetermined volume of water can correspond to an internal volume of the steam generator. 
     The determining of the volume of water can occur during the supplying of the water to the steam generator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic view of a steam washing machine comprising a steam generator according to one embodiment of the invention. 
         FIG. 2  is a schematic view of a first embodiment steam generator for use with the washing machine of  FIG. 1 . 
         FIG. 3  is a flow chart of a method of operating the steam washing machine of  FIG. 1  according to one embodiment of the invention to control a supply of water to the steam generator. 
         FIG. 4  is a schematic view of a second embodiment steam generator for use with the washing machine of  FIG. 1 . 
         FIG. 5  is a schematic view of a third embodiment steam generator for use with the washing machine of  FIG. 1 . 
         FIG. 6  is a schematic view of a fourth embodiment steam generator for use with the washing machine of  FIG. 1 , wherein the steam generator comprises a weight sensor shown in a condition corresponding to a steam generator weight greater than a predetermined weight. 
         FIG. 7  is a schematic view of the steam generator of  FIG. 6  with the weight sensor shown in a condition corresponding to a steam generator weight less than a predetermined weight. 
     
    
    
     DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     The invention provides methods and structures for controlling a supply of water to a steam generator of a fabric treatment appliance. The fabric treatment appliance can be any machine that treats fabrics, and examples of the fabric treatment appliance include, but are not limited to, a washing machine, including top-loading, front-loading, vertical axis, and horizontal axis washing machines; a dryer, such as a tumble dryer or a stationary dryer, including top-loading dryers and front-loading dryers; a combination washing machine and dryer; a tumbling or stationary refreshing machine; an extractor; a non-aqueous washing apparatus; and a revitalizing machine. For illustrative purposes, the invention will be described with respect to a washing machine, with it being understood that the invention can be adapted for use with any type of fabric treatment appliance having a steam generator. 
     Referring now to the figures,  FIG. 1  is a schematic view of an exemplary steam washing machine  10 . The washing machine  10  comprises a cabinet  12  that houses a stationary tub  14 . A rotatable drum  16  mounted within the tub  14  defines a fabric treatment chamber and includes a plurality of perforations  18 , and liquid can flow between the tub  14  and the drum  16  through the perforations  18 . The drum  16  further comprises a plurality of baffles  20  disposed on an inner surface of the drum  16  to lift fabric items contained in the drum  16  while the drum  16  rotates, as is well known in the washing machine art. A motor  22  coupled to the drum  16  through a belt  24  rotates the drum  16 . Both the tub  14  and the drum  16  can be selectively closed by a door  26 . 
     Washing machines are typically categorized as either a vertical axis washing machine or a horizontal axis washing machine. As used herein, the “vertical axis” washing machine refers to a washing machine comprising a rotatable drum, perforate or imperforate, that holds fabric items and a fabric moving element, such as an agitator, impeller, nutator, and the like, that induces movement of the fabric items to impart mechanical energy to the fabric articles for cleaning action. In some vertical axis washing machines, the drum rotates about a vertical axis generally perpendicular to a surface that supports the washing machine. However, the rotational axis need not be vertical. The drum can rotate about an axis inclined relative to the vertical axis. As used herein, the “horizontal axis” washing machine refers to a washing machine having a rotatable drum, perforated or imperforate, that holds fabric items and washes the fabric items by the fabric items rubbing against one another as the drum rotates. In horizontal axis washing machines, the clothes are lifted by the rotating drum and then fall in response to gravity to form a tumbling action that imparts the mechanical energy to the fabric articles. In some horizontal axis washing machines, the drum rotates about a horizontal axis generally parallel to a surface that supports the washing machine. However, the rotational axis need not be horizontal. The drum can rotate about an axis inclined relative to the horizontal axis. Vertical axis and horizontal axis machines are best differentiated by the manner in which they impart mechanical energy to the fabric articles. The illustrated exemplary washing machine of  FIG. 1  is a horizontal axis washing machine. 
     The motor  22  can rotate the drum  16  at various speeds in opposite rotational directions. In particular, the motor  22  can rotate the drum  16  at tumbling speeds wherein the fabric items in the drum  16  rotate with the drum  16  from a lowest location of the drum  16  towards a highest location of the drum  16 , but fall back to the lowest location of the drum  16  before reaching the highest location of the drum  16 . The rotation of the fabric items with the drum  16  can be facilitated by the baffles  20 . Alternatively, the motor  22  can rotate the drum  16  at spin speeds wherein the fabric items rotate with the drum  16  without falling. 
     The washing machine  10  of  FIG. 1  further comprises a liquid supply and recirculation system. Liquid, such as water, can be supplied to the washing machine  10  from a household water supply  28 . A first supply conduit  30  fluidly couples the water supply  28  to a detergent dispenser  32 . An inlet valve  34  controls flow of the liquid from the water supply  28  and through the first supply conduit  30  to the detergent dispenser  32 . The inlet valve  34  can be positioned in any suitable location between the water supply  28  and the detergent dispenser  32 . A liquid conduit  36  fluidly couples the detergent dispenser  32  with the tub  14 . The liquid conduit  36  can couple with the tub  14  at any suitable location on the tub  14  and is shown as being coupled to a front wall of the tub  14  in  FIG. 1  for exemplary purposes. The liquid that flows from the detergent dispenser  32  through the liquid conduit  36  to the tub  14  enters a space between the tub  14  and the drum  16  and flows by gravity to a sump  38  formed in part by a lower portion  40  of the tub  14 . The sump  38  is also formed by a sump conduit  42  that fluidly couples the lower portion  40  of the tub  14  to a pump  44 . The pump  44  can direct fluid to a drain conduit  46 , which drains the liquid from the washing machine  10 , or to a recirculation conduit  48 , which terminates at a recirculation inlet  50 . The recirculation inlet  50  directs the liquid from the recirculation conduit  48  into the drum  16 . The recirculation inlet  50  can introduce the liquid into the drum  16  in any suitable manner, such as by spraying, dripping, or providing a steady flow of the liquid. 
     The exemplary washing machine  10  further includes a steam generation system. The steam generation system comprises a steam generator  60  that receives liquid from the water supply  28  through a second supply conduit  62 . A flow controller  64  controls flow of the liquid from the water supply  28  and through the second supply conduit  62  to the steam generator  60 . The flow controller  64  can be positioned in any suitable location between the water supply  28  and the steam generator  60 . A steam conduit  66  fluidly couples the steam generator  60  to a steam inlet  68 , which introduces steam into the tub  14 . The steam inlet  68  can couple with the tub  14  at any suitable location on the tub  14  and is shown as being coupled to a rear wall of the tub  14  in  FIG. 1  for exemplary purposes. According to one embodiment of the invention, the steam inlet  68  is positioned at a height higher than a level corresponding to a maximum level of the liquid in the tub  14  to prevent backflow of the liquid into the steam conduit  66 . The steam that enters the tub  14  through the steam inlet  68  subsequently enters the drum  16  through the perforations  18 . Alternatively, the steam inlet  68  can be configured to introduce the steam directly into the drum  16 . The steam inlet  68  can introduce the steam into the tub  14  in any suitable manner. The washing machine  10  can further include an exhaust conduit that directs steam that leaves the tub  14  externally of the washing machine  10 . The exhaust conduit can be configured to exhaust the steam directly to the exterior of the washing machine  10 . Alternatively, the exhaust conduit can be configured to direct the steam through a condenser prior to leaving the washing machine  10 . 
     The steam generator  60  can be any type of device that converts the liquid to steam. For example, the steam generator  60  can be a tank-type steam generator that stores a volume of liquid and heats the volume of liquid to convert the liquid to steam. Alternatively, the steam generator  60  can be an in-line steam generator that converts the liquid to steam as the liquid flows through the steam generator  60 . The steam generator  60  can produce pressurized or non-pressurized steam. 
     In addition to producing steam, the steam generator  60 , whether an in-line steam generator, a tank-type steam generator, or any other type of steam generator, can heat water to a temperature below a steam transformation temperature, whereby the steam generator  60  produces hot water. The hot water can be delivered to the tub  14  and/or drum  16  from the steam generator  60 . The hot water can be used alone or can optionally mix with cold water in the tub  14  and/or drum  16 . Using the steam generator to produce hot water can be useful when the steam generator  60  couples only with a cold water source of the water supply  28 . 
       FIG. 2  is a schematic view of an exemplary in-line steam generator  60  for use with the washing machine  10 . The steam generator  60  comprises a housing or main body  70  in the form of a generally cylindrical tube. The main body  70  has an inside surface  72  that defines a steam generation chamber  74 . The steam generation chamber  74  is fluidly coupled to the second supply conduit  62  such that fluid from the second supply conduit  62  can flow through the flow controller  64  and can enter the steam generation chamber  74 . The steam generation chamber  74  is also fluidly coupled to the steam conduit  66  such that steam generated in the steam generation chamber  74  can flow into the steam conduit  66 . The flow of fluid into and steam out of the steam generation chamber  74  is represented by arrows in  FIG. 2 . 
     The flow controller  64  effects a flow of water through the second supply conduit  62  and also restricts a flow rate of the water through the second supply conduit  62 . The pressure and, therefore, flow rate of water associated with the water supply  28  can vary depending on geography (i.e., the pressure can vary from country to country and within a country, such as from municipality to municipality within the United States). To accommodate this variation in pressure and provide a relatively constant flow rate, the flow controller  64  restricts the flow rate through the second supply conduit  62  to a restricted flow rate that is less than the flow rate of the water supply  28 . 
     The flow controller  64  can take on many forms, and one example of the flow controller  64  comprises a valve  90  and a restrictor  92 . The valve  90  can be any suitable type of valve that can open to allow water to flow through the second supply conduit  62  to the steam generation chamber  74  and close to prevent water from flowing through the second supply conduit  62  to the steam generation chamber  74 . For example, the valve  90  can be a solenoid valve having an “on” or open position and an “off” or closed position. The restrictor  92  can be any suitable type of restrictor that restricts the flow rate of water through the second supply conduit  62 . For example, the restrictor  92  can be a rubber flow restrictor, such as a rubber disc-like member, located within the second supply conduit  62 . 
     Both the valve  90  and the restrictor  92  have a corresponding flow rate. According to one embodiment and as illustrated in  FIG. 2 , the restrictor  92  can have a restrictor flow rate that is greater than a valve flow rate, which is the flow rate of the valve  90 . With such relative flow rates, the restrictor  92  can be located upstream from the valve  90  whereby the restrictor  92  restricts the flow rate of the water supply  28  to provide a relatively constant flow rate, and the valve  90  further restricts the flow rate and simultaneously controls the flow of water through the second supply conduit  62 . 
     According to another embodiment, the restrictor flow rate can be less than the valve flow rate, and the restrictor  92  can be located downstream from the valve  90 . For this configuration, the valve  90  can open to allow the water to flow through the valve  90  at the valve flow rate, and the restrictor  92  reduces the flow rate of the water from the valve flow rate to the restrictor flow rate. 
     According to yet another embodiment, the valve  90  and the restrictor  92  can be integrated into a single unit whereby the valve  90  and the restrictor effectively simultaneously effect water flow through the second supply conduit  62  and restrict the flow rate through the second supply conduit  62  to a flow rate less than that associated with the water supply  28 . 
     Regardless of the relative configuration of the valve  90  and the restrictor  92 , the valve  90  can be configured to supply the fluid to the steam generator  60  in any suitable manner. For example, the fluid can be supplied in a continuous manner or according to a duty cycle where the fluid is supplied for discrete periods of time when the valve  90  is open separated by discrete periods of time when the valve  90  is closed. Thus, for the duty cycle, the periods of time when the fluid can flow through the valve  90  alternate with the periods of time when the fluid cannot flow through the valve  90 . 
     Alternatively, the flow controller  64  can comprise a proportional valve that performs the functions of both the valve  90  and the restrictor  92 , i.e., the controlling the flow of water and controlling the rate of the flow through the second supply conduit  62 . In this way, the proportion valve can provide a continuous supply of water at the desired flow rate, without the need for cycling the valve in accordance with a duty cycle. The proportional valve can be any suitable type of proportional valve, such as a solenoid proportional valve. 
     The steam generator  60  further comprises a heater body  76  and a heater  78  embedded in the heater body  76 . The heater body  76  is made of a material capable of conducting heat. For example, the heater body  76  can be made of a metal, such as aluminum. The heater body  76  of the illustrated embodiment is shown as being integrally formed with the main body  70 , but it is within the scope of the invention for the heater body  76  to be formed as a component separate from the main body  70 . In the illustrated embodiment, the main body  70  can also be made of a heat conductive material, such as metal. As a result, heat generated by the heater  78  can conduct through the heater body  76  and the main body  70  to heat fluid in the steam generation chamber  74 . The heater  78  can be any suitable type of heater, such as a resistive heater, configured to generate heat. A thermal fuse  80  can be positioned in series with the heater  78  to prevent overheating of the heater  78 . Alternatively, the heater  78  can be located within the steam generation chamber  74  or in any other suitable location in the steam generator  60 . 
     The steam generator  60  further includes a temperature sensor  82  that can sense a temperature of the steam generation chamber  74  or a temperature representative of the temperature of the steam generation chamber  74 . The temperature sensor  82  of the illustrated embodiment is coupled to the main body  70 ; however, it is within the scope of the invention to employ temperature sensors in other locations. For example, the temperature sensor  82  can be a probe-type sensor that extends through the inside surface  72  into the steam generation chamber  74 . 
     The temperature sensor  82  and the heater  78  can be coupled to a controller  84 , which can control the operation of heater  78  in response to information received from the temperature sensor  82 . The controller  84  can also be coupled to the flow controller  64 , such as to the valve  90  of the flow controller  64  of the illustrated embodiment, to control the operation of the flow controller  64  and can include a timer  86  to measure a time during which the flow controller  64  effects the flow of water through the second supply conduit  62 . 
     The washing machine  10  can further comprise a controller coupled to various working components of the washing machine  10 , such as the pump  44 , the motor  22 , the inlet valve  34 , the flow controller  64 , the detergent dispenser  32 , and the steam generator  60 , to control the operation of the washing machine  10 . The controller can receive data from the working components and can provide commands, which can be based on the received data, to the working components to execute a desired operation of the washing machine  10 . 
     The liquid supply and recirculation system and the steam generator system can differ from the configuration shown in  FIG. 1 , such as by inclusion of other valves, conduits, wash aid dispensers, and the like, to control the flow of liquid and steam through the washing machine  10  and for the introduction of more than one type of detergent/wash aid. For example, a valve can be located in the liquid conduit  36 , in the recirculation conduit  48 , and in the steam conduit  66 . Furthermore, an additional conduit can be included to couple the water supply  28  directly to the tub  14  or the drum  16  so that the liquid provided to the tub  14  or the drum  16  does not have to pass through the detergent dispenser  32 . Alternatively, the liquid can be provided to the tub  14  or the drum  16  through the steam generator  60  rather than through the detergent dispenser  32  or the additional conduit. As another example, the recirculation conduit  48  can be coupled to the liquid conduit  36  so that the recirculated liquid enters the tub  14  or the drum  16  at the same location where the liquid from the detergent dispenser  32  enters the tub  14 . 
     The washing machine of  FIG. 1  is provided for exemplary purposes only. It is within the scope of the invention to perform the inventive methods described below or use the steam generator  60  on other types of washing machines, examples of which are disclosed in: our Ser. No. 11/450,365, titled “Method of Operating a Washing Machine Using Steam;” our Ser. No. 11/450,529, titled “Steam Washing Machine Operation Method Having Dual Speed Spin Pre-Wash;” and our Ser. No. 11/450,620, titled “Steam Washing Machine Operation Method Having Dry Spin Pre-Wash,” all filed Jun. 9, 2006, which are incorporated herein by reference in their entirety. 
     A method  100  of operating the washing machine  10  to control the supply of water to the steam generator  60  according to one embodiment of the invention is illustrated in the flow chart of  FIG. 3 . In general, the method  100  comprises a step  102  of supplying water to the steam generator  60  followed by a step  104  of generating steam from the supplied water. Either during or after the generation of steam in the step  104 , water can be resupplied to the steam generator  60  in a step  106  to replenish the water in the steam generator  60  that has converted to steam. In step  108 , it is determined if the steam generation is complete, which can be determined in any suitable manner. For example, the steam generation can occur for a predetermined period of time or until a fabric load in the fabric treatment chamber achieves a predetermined temperature. If the steam generation is not complete, then the steps  104 ,  106  of generating the steam and resupplying the water to the steam generator  60  are repeated until it is determined that the steam generation is complete. The steps  104 ,  106 ,  108  can be performed sequentially or simultaneously. 
     The method  100  can be executed in the following manner when using the steam generator  60  having the flow controller  64 . Because the flow rate of the flow controller  64  is known, the flow controller  64  can supply a first known volume of water during the step  102  of supplying water to the steam generator  60  by operating for a first predetermined time. In other words, the first predetermined time for operating the flow controller  64  (units=time) can be calculated by multiplying the first known volume of water (units=volume) by the inverse of the flow rate of the flow controller  64  (units=time/volume). When calculating the first predetermined time, the flow rate of the controller  64  equals the smaller of the valve flow rate and the restrictor flow rate (assuming the flow controller  64  comprises both the valve  90  and the restrictor  92 ) as the smaller flow rate determines the flow rate of the water that enters the steam generation chamber  74 . Once the first predetermined time is determined, the controller  84  opens the valve  90  for the first predetermined time, which can be measured by the timer  86 , to supply the first known volume of water. 
     In practice, the controller of the washing machine  10  might not actually execute the above calculation of the first predetermined time. Rather, the controller can be programmed with data sets relating volume and time for one or more flow rates, and the controller can refer to the data sets instead of performing calculations during the operation of the washing machine  10 . 
     The first known volume of water can be any suitable volume. In an initial supply of water to the steam generator  60 , for example, the first known volume of water can correspond to the volume of the steam generation chamber  74  to completely fill the steam generation chamber  74  with water. 
     The steam generator  60  converts the supplied water to steam and thereby consumes the water in the steam generation chamber  74 . Knowing a rate of steam generation during the steam generation step  104  enables a determination of the volume of water converted to steam and thereby removed from the steam generation chamber  74 . The resupplying of the water in the step  106  can comprise supplying a second known volume of water to increase the water level in the steam generation chamber  74  and replace the water that has converted to steam and exited the steam generation chamber  74 . The second known volume of water can be supplied during the step  106  of resupplying the water for a second predetermined time, which can be calculated in a manner similar to that described above with respect to the first predetermined time. Once the second predetermined time is determined, the controller  84  opens the valve  90  for the second predetermined time, which can be measured by the timer  86 , to supply the second known volume of water. 
     Optionally, the resupplying of the water can maintain the first known volume of water supplied to the steam generator  60 . Alternatively, the resupplying of the water can increase the water level in the steam generation chamber  74  above that achieved with the first predetermined known of water or maintain a water level the steam generation chamber  74  below that achieved with the first known volume of water. When the second known volume of water is less than the first known volume of water, the second predetermined time is logically less than the first predetermined time as the flow rate through the second supply conduit  62  remains constant. The resupplying of the water can occur at discrete intervals, such as after certain time periods of steam generation, or continuously during the generation of steam. 
     An alternative steam generator  60 A is illustrated in  FIG. 4 , where components similar to those of the first embodiment steam generator  60  are identified with the same reference numeral bearing the letter “A.” The steam generator  60 A is a tank-type steam generator comprising a housing or main body  70 A in the form of a generally rectangular tank. The main body  70 A has an inside surface  72 A that defines a steam generation chamber  74 A. The steam generation chamber  74 A is fluidly coupled to the second supply conduit  62  such that fluid from the water supply  28  can flow through a valve  94  in the second supply conduit  62  and can enter the steam generation chamber  74 A, as indicated by the solid arrows entering the steam generation chamber  74 A in  FIG. 4 . The steam generation chamber  74 A is also fluidly coupled to the steam conduit  66  such that steam from the steam generation chamber  74 A can flow through the steam conduit  66  to the drum  16 , as depicted by solid arrows leaving the steam generation chamber  74 A in  FIG. 4 . 
     A flow meter  96  located in the second supply conduit  62  determines a flow of water through the second supply conduit  62  and into the steam generation chamber  74 A. The flow meter  96  can have any suitable output representative of the flow of water through the second supply conduit  62 . For example, the output of the flow meter  96  can be a flow rate of the water through the second supply conduit  62  or a volume of water supplied through the second supply conduit  62 . 
     The steam generator  60 A further comprises a heater  78 A, which is shown as being embedded in the main body  70 A. It is within the scope of the invention, however, to locate the heater  78 A within the steam generation chamber  74 A or in any other suitable location in the steam generator  60 A. When the heater  78 A is embedded in the main body  70 A, the main body  70 A is made of a material capable of conducting heat. For example, the main body  70 A can be made of a metal, such as aluminum. As a result, heat generated by the heater  78 A can conduct through the main body  70 A to heat fluid in the steam generation chamber  74 A. The heater  78 A can be any suitable type of heater, such as a resistive heater, configured to generate heat. A thermal fuse  80 A can be positioned in series with the heater  78 A to prevent overheating of the heater  78 A. 
     The steam generator  60 A further includes a temperature sensor  82 A that can sense a temperature of the steam generation chamber  74 A or a temperature representative of the temperature of the steam generation chamber  74 A. The temperature sensor  82 A of the illustrated embodiment is a probe-type sensor that projects into the steam generation chamber  74 A; however, it is within the scope of the invention to employ temperature sensors in other locations. 
     The temperature sensor  82 A and the heater  78 A can be coupled to a controller  84 A, which can control the operation of heater  78 A in response to information received from the temperature sensor  82 A. The controller  84 A can also be coupled to the valve  94  and the flow meter  96  to control the operation of the valve  94  and can include a timer  86 A to measure a time during which the valve  94  effects the flow of water through the second supply conduit  62 . 
     The method  100  of operating the washing machine  10  illustrated in the flow chart of  FIG. 3  can also be executed with the second embodiment steam generator  60 A of  FIG. 4 . The execution of the method  100  differs from the exemplary execution described above with respect to the first embodiment steam generator  60  due to the use of the flow meter  96  in the second embodiment steam generator  60 A rather than the flow controller  64 . 
     The method  100  can be executed in the following manner when using the steam generator  60 A having the flow meter  96 . For the step  102  of supplying the water to the steam generator  60 A, output from the flow meter  96  can be used to determine a volume of water supplied to the steam generation chamber  74 A while the water is being supplied through the second supply conduit  62 . 
     For example, in one embodiment, the flow meter  96  can sense the flow rate of the water through the second supply conduit  62  (units=volume/time), and the flow rate can be multiplied by the time the water has been supplied as determined by the timer  86 A (units=time) to calculate the volume of water supplied (units=volume). In practice, the controller of the washing machine  10  might not actually execute the above calculation of the volume of water supplied. Rather, the controller can be programmed with data sets relating time and volume for one or more flow rates, and the controller can refer to the data sets instead of performing calculations during the operation of the washing machine  10 . Alternatively, the flow meter  96  can directly output the volume of water supplied, thereby negating the need to calculate the volume. 
     The output from the flow meter  96  can be used to supply a first predetermined volume of water to the steam generator  60 A in the step  102 , whereby the controller  84 A opens the valve  94  to begin the supply of the first predetermined volume of water and closes the valve  94  when the output from the flow meter  96  communicates that the first predetermined volume of water has been supplied. 
     The first predetermined volume of water can be any suitable volume. In an initial supply of water to the steam generator  60 A, for example, the first predetermined volume of water can correspond to the volume of the steam generation chamber  74 A to completely fill the steam generation chamber  74 A with water. 
     The steam generator  60 A converts the supplied water to steam and thereby consumes the water in the steam generation chamber  74 A. Knowing a rate of steam generation during the steam generation step  104  enables a determination of the volume of water converted to steam and thereby removed from the steam generation chamber  74 A. The resupplying of the water in the step  106  can comprise supplying a second predetermined volume of water to increase the water level in the steam generation chamber  74 A and replace the water that has converted to steam and exited the steam generation chamber  74 A. The second predetermined volume of water can be supplied during the step  106  of resupplying the water in the manner described above for supplying the first predetermined volume of water. In particular, the controller  84 A opens the valve  94  to begin the supply of the second predetermined volume of water, the output of the flow meter  96  can be used to determine the volume of water supplied through the second supply conduit  62  as the water is being supplied, and the controller  84 A closes the valve  94  to stop the supply when the second predetermined volume of water has been supplied. 
     Optionally, the resupplying of the water can maintain the first predetermined volume of water supplied to the steam generator  60 A. Alternatively, the resupplying of the water can increase the water level in the steam generation chamber  74 A above that achieved with the first predetermined volume of water or maintain a water level the steam generation chamber  74 A below that achieved with the first predetermined volume of water. The resupplying of the water can occur at discrete intervals, such as after certain time periods of steam generation, or continuously during the generation of steam. 
     While the flow controller  64  has been described with respect to an in-line steam generator, and the flow meter  96  has been described with respect to a tank-type steam generator, it is within the scope of the invention to utilize any type of steam generator with the flow controller  64  and any type of steam generator with the flow meter  96 . For example, the flow controller  64  can be used on a tank-type steam generator, and the flow meter  96  can be employed with an in-line steam generator. Further, any type of steam generator can be utilized for executing the method  100 . The execution of the method  100  is not intended to be limited for use only with steam generators comprising the flow controller  64  and the flow meter  96 . 
     An alternative steam generator  60 B is illustrated in  FIG. 5 , where components similar to those of the first and second embodiment steam generators  60 ,  60 A are identified with the same reference numeral bearing the letter “B.” The steam generator  60 B is substantially identical to the first embodiment steam generator  60 , except the fluid flow through the second supply conduit  62  is controlled by a valve  94 , the main body  70 B includes an ascending outlet portion  98 , and the temperature sensor  82 B is positioned to detect a temperature representative of the steam generation chamber  74 B at a predetermined water level in the steam generation chamber  74 B, which in the illustrated embodiment is at the ascending outlet portion  98 . The controller  84 B is coupled to the temperature sensor  82 B, the heater  78 B, and the valve  94  to control operation of the steam generator  60 B. 
     The ascending outlet portion  98  is illustrated as being integral with the main body  70 B; however, it is within the scope of the invention for the ascending outlet portion  98  to be a separate component or conduit that fluidly couples the main body  70 B to the steam conduit  66 . Regardless of the configuration of the ascending outlet portion  98 , the interior of the ascending outlet portion  98  forms a portion of the steam generation chamber  74 B. In other words, the steam generation chamber  74 B extends into the ascending outlet portion  98 .  FIG. 5  illustrates the predetermined water level as a dotted line WL located in the ascending outlet portion  98 . The predetermined water level can be a minimum water level in the steam generation chamber  74  or any other water level, including a range of water levels. 
     The temperature sensor  82 B can detect the temperature representative of the steam generation chamber  74 B in any suitable manner. For example, the temperature sensor  82 B can detect the temperature by directly sensing a temperature of the main body  70 B or other structural housing that forms the ascending outlet portion  98 . Directly sensing the temperature of the main body  70 B can be accomplished by locating or mounting the temperature sensor  82 B on the main body  70 B, as shown in the illustrated embodiment. Alternatively, the temperature sensor  82 B can detect the temperature by directly sensing a temperature of the steam generation chamber  74 B, such as by being located inside or at least projecting partially into the steam generation chamber  74 B. Furthermore, it is within the scope of the invention to locate the temperature sensor  82 B at the location corresponding to the predetermined water level or at another location where the temperature sensor  82 B is capable of detecting the temperature representative of the steam generation chamber  74 B at the predetermined water level. 
     In general, during operation of the steam generator  60 B, the temperature sensor  82 B detects the temperature representative of the steam generation chamber  74 B at the predetermined water level in the steam generation chamber  74 B and sends an output to the controller  84 B. The controller  84 B controls the valve  94  to supply water to the steam generator based on the output from the temperature sensor  82 B. 
     The operation of the steam generator  60 B with respect to the temperature sensor  82 B illustrated in  FIG. 5  will be described with an initial assumption that water has been supplied to the steam generation chamber  74 B via the second supply conduit  62  and the valve  94  to at least the predetermined water level. Once the water has been supplied to at least the predetermined water level and the heater  78 B is powered to heat the water to a steam generation temperature, the temperature sensor  82 B detects a relatively stable temperature as long as the water level in the steam generation chamber  74 B remains near the predetermined level. The output of the temperature sensor  82 B will inherently have some fluctuation, and the determination of whether the output is relatively stable can be made, for example, by determining if the fluctuation of the output is within a predetermined amount of acceptable fluctuation. 
     As the water converts to steam and the water level in the steam generation chamber  74 B drops below the predetermined water level, the temperature sensor  82 B detects a relatively sharp increase in temperature. The sharp increase in temperature results from the absence of water in the steam generation chamber  74 B at the predetermined water level. The controller  84 B can recognize the sensed temperature increase as a relatively unstable output of the temperature sensor  82 B. As stated above, the output of the temperature sensor  82 B will inherently have some fluctuation, and the determination of whether the output is relatively unstable can be made, for example, by determining if the fluctuation of the output exceeds the predetermined amount of acceptable fluctuation. In response to the increase in the temperature, the controller  84 B opens the valve  94  to supply water to the steam generation chamber  74 B. It is within the scope of the invention for the water level to exceed the predetermined water level when the water is supplied into the steam generation chamber  74 B, especially when the predetermined water level corresponds to the minimum water level. The controller  84 B closes the valve  94  to stop the supplying of the water when the output of the temperature sensor  82 B is relatively stable, thereby indicating that the water level has achieved or exceeded the predetermined water level. The detection of the temperature and the supplying of the water can occur at discrete intervals or continuously during the generation of steam. 
     The controller  84 B can open and close the valve  94  based on any suitable logic in addition to the stable output method just described. For example, the controller  84 B can compare the sensed temperature to a predetermined temperature, whereby the controller  84 B opens the valve  94  when the sensed temperature is greater than the predetermined temperature and stops the supplying of water by closing the valve  94  when the sensed temperature returns to or becomes less than the predetermined temperature. In this example, the predetermined temperature can alternatively comprise an upper predetermined temperature above which the valve  94  opens and a lower predetermined temperature below which the valve  94  closes. Utilizing the upper and lower predetermined temperatures provides a range that can account for natural fluctuation in the output of the temperature sensor  82 B. Alternatively, when the temperature increases, the controller  84 B can compare the sensed temperature increase to a predetermined temperature increase and determine that the water has dropped below the predetermined level when the sensed temperature increase exceeds the predetermined temperature increase. 
     While the use of the temperature sensor  82 B to control the supplying of water to the steam generation chamber  74 B has been described with respect to an in-line steam generator, it is within the scope of the invention to utilize any type of steam generator, including a tank-type steam generator, with the temperature sensor  82 B and the corresponding method of controlling the supply of water with the temperature sensor  82 B. 
     An alternative steam generator  60 C is illustrated in  FIG. 6 , where components similar to those of the first, second, and third embodiment steam generators  60 ,  60 A,  60 B are identified with the same reference numeral bearing the letter “C.” The steam generator  60 C is substantially identical to the second embodiment steam generator  60 A, except that the former lacks the flow meter  96  and includes a weight sensor  120  that outputs a signal responsive to the weight of the steam generator  60 . The controller  84 C is coupled to the weight sensor  120 , the heater  78 C, and the valve  94  to control operation of the steam generator  60 C. 
     The weight sensor  120  of the illustrated embodiment comprises a biasing member  122  and a switch  124 . The biasing member  122  can be any suitable device that supports at least a portion of the weight of the steam generator  60 C and exerts an upward force on the steam generator  60 C. In the exemplary embodiment of  FIG. 6 , the biasing member  122  comprises a coil compression spring. The switch  124  can be any suitable switching device and actuates or changes state when the weight of the steam generator  60 C decreases to below a predetermined weight. Because the supply of water into and evaporation of water from the steam generation chamber  74 B alters the weight of the steam generator  60 C, the weight of the steam generator  60 C directly corresponds to the amount of water in the steam generation chamber  74 B. Thus, the predetermined weight corresponds to a predetermined amount of water in the steam generation chamber  74 C. The switch  124  is illustrated as being located below the steam generator  60 C, but it is within the scope of the invention for the switch  124  to be located in any suitable position relative to the steam generator  60 C. 
     In general, during the operation of the steam generator  60 C, the weight sensor  120  outputs a signal representative of the weight of the steam generator  60 C, and the controller  84 C utilizes the output to determine a status of the water in the steam generator  60 C. For example, the status of the water can be whether the amount of water in the steam generator is sufficient (e.g., whether the water at least reaches a predetermined water level). Based on the determined status, the controller  84 C controls the supply of the water to the steam generator  60 C. 
     The operation of the steam generator  60 C with respect to the weight sensor  120  illustrated in  FIG. 6  will be described with an initial assumption that water has been supplied to the steam generation chamber  74 C via the second supply conduit  62  and the valve  94  to a level corresponding to an amount of water in the steam generation chamber  74 C greater than or equal to a predetermined amount of water. It follows that the amount of water greater than the predetermined amount of water corresponds to a weight of the steam generator greater than a predetermined weight of the steam generator  60 C. As shown in  FIG. 6 , when the amount of water/weight of the steam generator  60 C is greater than the predetermined amount of water/predetermined weight of the steam generator  60 C, the weight of the steam generator  60 C overcomes the upward force applied by the biasing member  122  and depresses the switch  124 , as shown in phantom in  FIG. 6 . The depression of the switch  124  communicates to the controller  84 C that the weight of the steam generator is greater than or equal to predetermined weight (i.e., the water level in the steam generation chamber  74 C is sufficient), and the controller  84 C closes the valve  94  to prevent supply of water to the steam generation chamber  74 C. 
     As the heater  78 C heats the water in the steam generation chamber  74 B, the water converts to steam and leaves the steam generation chamber  74 B through the steam conduit  66 , as illustrated by arrows in  FIG. 6 . Consequently, the amount of water in the steam generation chamber  74 B decreases. Referring now to  FIG. 7 , when the amount of water decreases to below the predetermined amount of water, the weight of the steam generator  60 C is no longer sufficient to overcome the upward force of the biasing member  122 , and biasing member  122  lifts the steam generator  60 C from the switch  124 , which thereby actuates or changes state to communicate to the controller  84 C that the weight of the steam generator  60 C is less than the predetermined weight (i.e., the water level in the steam generation chamber  74 C is not sufficient). In response, the controller  84 B opens the valve  94  to supply water to the steam generation chamber  74 B via the second supply conduit  62 , as indicated by arrows entering the steam generation chamber  74 B in  FIG. 7 . The controller  84 B can close the valve  94  to stop the supply of water when the amount of water/weight of the steam generator  60 C reaches or exceeds the predetermined amount of water/predetermined weight of the steam generator  60 C, as indicated by depression of the switch  124 . 
     The predetermined amount of water/predetermined weight of the steam generator  60 C can be any suitable amount/weight, such as a minimum amount/weight. Further, the predetermined amount/weight can be a single value or can comprise a range of values. The determining of the status of the water and the supplying of the water can occur at discrete intervals or continuously during the generation of steam. 
     As stated above, the switch  124  can be located in any suitable position relative to the steam generator  60 C. For example, the switch  124  can be located above the steam generator  60 C whereby the switch depresses when the weight of the steam generator  60 C falls below the predetermined weight or on a side of the steam generator  60 C, which can include a projection that actuates or changes a state of the switch  124  as the steam generator  60 C moves vertically due to a change in weight. The switch  124  can comprise any type of mechanical switch, such as that described above with respect to  FIGS. 6 and 7 , or can comprise any other type of switch, such as one that includes an infrared sensor that detects the relative positioning of the steam generator  60 C to determine the relative weight of the steam generator  60 C. 
     As an alternative to the weight sensor  120  comprising the biasing member  120  and the switch  124 , the weight sensor can be any suitable device capable of generating a signal responsive to the weight of the steam generator  60 C. For example, the weight sensor can be a scale that measures the weight of the steam generator  60 C. The controller  84 C can be configured to open the valve  94  to supply a predetermined volume of water corresponding to the measured weight of the steam generator  60 C. In other words, the predetermined volume of water can be proportional to the measured weight of the steam generator  60 C. 
     While the use of the weight sensor  120  to control the supplying of water to the steam generation chamber  74 C has been described with respect to a tank-type steam generator, it is within the scope of the invention to utilize any type of steam generator, including an in-line steam generator, with the weight sensor  120  and the corresponding method of controlling the supply of water with the weight sensor  120 . 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.