Patent Publication Number: US-9416476-B2

Title: Laundry treating appliance and method of controlling the heater thereof

Description:
BACKGROUND 
     Laundry treating appliances, such as clothes washing machines and clothes dryers, may include current drawing components for treating laundry items in a rotatable drum that defines a treating chamber according to a cycle of operation. The current drawing components may include a motor or a heating element. Current/power drawn by the components may be controlled to avoid circuit breaker tripping. 
     BRIEF SUMMARY 
     According to an embodiment of the invention, a method of operating a laundry treating appliance having a drum at least partially defining a treating chamber, and a plurality of electrical components including a motor rotatably driving the drum, and a heater heating fluid provided to the treating chamber, comprises determining a parameter indicative of the electricity consumed by at least some of the plurality of electrical components and providing the parameter to the controller, comparing, with the controller, the consumed electricity to a threshold value for the parameter, and adjusting the thermal output of the heater to maintain the parameter below the threshold value. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic view of a laundry treating appliance in the form of a washing machine according to a first embodiment of the invention. 
         FIG. 2  is a schematic of a control system of the laundry treating appliance of  FIG. 1  according to the first embodiment of the invention. 
         FIG. 3  is a schematic heating cycle for the first and second heating elements with respect to the motor operation according to a second embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic view of a laundry treating appliance according to a first embodiment of the invention. The laundry treating appliance may be any appliance which performs a cycle of operation to clean or otherwise treat items placed therein, non-limiting examples of which include a horizontal or vertical axis clothes washer; a combination washing machine and dryer; a tumbling or stationary refreshing/revitalizing machine; an extractor; a non-aqueous washing apparatus; and a revitalizing machine. 
     The laundry treating appliance of  FIG. 1  is illustrated as a washing machine  10 , which may include a structural support system comprising a cabinet  12  which defines a housing within which a laundry holding system resides. The cabinet  12  may be a housing having a chassis and/or a frame, defining interior enclosing components typically found in a conventional washing machine, such as motors, pumps, fluid lines, controls, sensors, transducers, and the like. Such components will not be described further herein except as necessary for a complete understanding of the invention. 
     The laundry holding system comprises a tub  14  supported within the cabinet  12  by a suitable suspension system and a drum  16  provided within the tub  14 , the drum  16  defining at least a portion of a laundry treating chamber  18 . The drum  16  may include a plurality of perforations  20  such that liquid may flow between the tub  14  and the drum  16  through the perforations  20 . A plurality of baffles  22  may be disposed on an inner surface of the drum  16  to lift the laundry load received in the treating chamber  18  while the drum  16  rotates. It is also within the scope of the invention for the laundry holding system to comprise only a tub with the tub defining the laundry treating chamber. 
     The laundry holding system may further include a door  24  which may be movably mounted to the cabinet  12  to selectively close both the tub  14  and the drum  16 . A bellows  26  may couple an open face of the tub  14  with the cabinet  12 , with the door  24  sealing against the bellows  26  when the door  24  closes the tub  14 . 
     The washing machine  10  may further include a suspension system  28  for dynamically suspending the laundry holding system within the structural support system. 
     The washing machine  10  may further include a liquid supply system for supplying water to the washing machine  10  for use in treating laundry during a cycle of operation. The liquid supply system may include a source of water, such as a household water supply  40 , which may include separate valves  42  and  44  for controlling the flow of hot and cold water, respectively. Water may be supplied through an inlet conduit  46  directly to the tub  14  by controlling first and second diverter mechanisms  48  and  50 , respectively. The diverter mechanisms  48 ,  50  may be a diverter valve having two outlets such that the diverter mechanisms  48 ,  50  may selectively direct a flow of liquid to one or both of two flow paths. Water from the household water supply  40  may flow through the inlet conduit  46  to the first diverter mechanism  48  which may direct the flow of liquid to a supply conduit  52 . The second diverter mechanism  50  on the supply conduit  52  may direct the flow of liquid to a tub outlet conduit  54  which may be provided with a spray nozzle  56  configured to spray the flow of liquid into the tub  14 . In this manner, water from the household water supply  40  may be supplied directly to the tub  14 . 
     The washing machine  10  may also be provided with a dispensing system for dispensing treating chemistry to the treating chamber  18  for use in treating the laundry according to a cycle of operation. The dispensing system may include a dispenser  62  which may be a single use dispenser, a bulk dispenser or a combination of a single and bulk dispenser. 
     Regardless of the type of dispenser used, the dispenser  62  may be configured to dispense a treating chemistry directly to the tub  14  or mixed with water from the liquid supply system through a dispensing outlet conduit  64 . The dispensing outlet conduit  64  may include a dispensing nozzle  66  configured to dispense the treating chemistry into the tub  14  in a desired pattern and under a desired amount of pressure. For example, the dispensing nozzle  66  may be configured to dispense a flow or stream of treating chemistry into the tub  14  by gravity, i.e. a non-pressurized stream. Water may be supplied to the dispenser  62  from the supply conduit  52  by directing the diverter mechanism  50  to direct the flow of water to a dispensing supply conduit  68 . 
     Non-limiting examples of treating chemistries that may be dispensed by the dispensing system during a cycle of operation include one or more of the following: water, enzymes, fragrances, stiffness/sizing agents, wrinkle releasers/reducers, softeners, antistatic or electrostatic agents, stain repellants, water repellants, energy reduction/extraction aids, antibacterial agents, medicinal agents, vitamins, moisturizers, shrinkage inhibitors, and color fidelity agents, and combinations thereof. 
     The washing machine  10  may also include a recirculation and drain system for recirculating liquid within the laundry holding system and draining liquid from the washing machine  10 . Liquid supplied to the tub  14  through tub outlet conduit  54  and/or the dispensing supply conduit  68  typically enters a space between the tub  14  and the drum  16  and may flow by gravity to a sump  70  formed in part by a lower portion of the tub  14 . The sump  70  may also be formed by a sump conduit  72  that may fluidly couple the lower portion of the tub  14  to a pump  74 . The pump  74  may direct liquid to a drain conduit  76 , which may drain the liquid from the washing machine  10 , or to a recirculation conduit  78 , which may terminate at a recirculation inlet  80 . The recirculation inlet  80  may direct the liquid from the recirculation conduit  78  into the drum  16 . The recirculation inlet  80  may introduce the liquid into the drum  16  in any suitable manner, such as by spraying, dripping, or providing a steady flow of liquid. In this manner, liquid provided to the tub  14 , with or without treating chemistry may be recirculated into the treating chamber  18  for treating the laundry within. 
     The liquid supply and/or recirculation and drain system may be provided with a heating system which may include one or more heaters for heating laundry and/or liquid supplied to the tub  14 , such as a steam generator  82  and/or a sump heater  84 . Liquid from the household water supply  40  may be provided to the steam generator  82  through the inlet conduit  46  by controlling the first diverter mechanism  48  to direct the flow of liquid to a steam supply conduit  86 . Steam generated by the steam generator  82  may be supplied to the tub  14  through a steam outlet conduit  87 . The steam generator  82  may be any suitable type of steam generator such as a flow through steam generator or a tank-type steam generator. Alternatively, the sump heater  84  may be used to generate steam in place of or in addition to the steam generator  82 . In addition or alternatively to generating steam, the steam generator  82  and/or sump heater  84  may be used to heat the laundry and/or liquid within the tub  14  as part of a cycle of operation. 
     The heater, such as the sump heater  84  or the steam generator  82 , may include one or more heating elements. For example, the sump heater  84  may include dual heating elements for heating laundry and/or liquid in the tub  14  or a single heating element with separately energizable portions. In another embodiment, the sump heater  84  may include more than two heating elements. Each of the dual heating elements may be configured to have identical thermal output capability, while combining heating elements with different thermal output capabilities are also possible. Similarly, the steam generator  82  may include multiple heating elements in generating steam for treating laundry. 
     One or more temperature sensors  85  may be provided to the sump  70  or other suitable locations of the washing machine  10  to operably measure the temperature of the sump heater  84 , atmosphere in the tub  14 , and/or liquid supplied to the tub  14 . The temperature sensor  85 , without limitation, may be in the form of NTC temperature sensor or PTC temperature sensor. The temperature sensor  85  may be also coupled to the steam generator  82  to measure the temperature of the steam generator to provide the temperature to the controller  96 . 
     Additionally, the liquid supply and recirculation and drain system may differ from the configuration shown in  FIG. 1 , such as by inclusion of other valves, conduits, treating chemistry dispensers, sensors, such as water level sensors and weight sensor, and the like, to control the flow of liquid through the washing machine  10  and for the introduction of more than one type of treating chemistry. 
     The washing machine  10  also includes a drive system for rotating the drum  16  within the tub  14 . The drive system may include a motor  88 , which may be directly coupled with the drum  16  through a drive shaft  90  to rotate the drum  14  about a rotational axis during a cycle of operation. The motor  88  may be a brushless permanent magnet (BPM) motor having a stator  92  and a rotor  94 . Alternately, the motor  88  may be coupled to the drum  16  through a belt and a drive shaft to rotate the drum  16 , as is known in the art. Other motors, such as an induction motor or a permanent split capacitor (PSC) motor, may also be used. The motor  88  may rotate the drum  16  at various speeds in either rotational direction. 
     The motor  88  may include a motor torque sensor (not shown). The motor torque sensor may be any suitable sensor, such as a voltage or current sensor, for outputting a parameter, such as a continuous or discrete current or voltage signal, indicative of the current or voltage supplied to the motor  88  to determine the torque applied by the motor  88 . The motor torque sensor may be a physical sensor or may be integrated with the motor  88 . 
     The washing machine  10  also includes a control system for controlling the operation of the washing machine  10  to implement one or more cycles of operation. The control system may include a controller  96  located within the cabinet  12  and a user interface  98  that is operably coupled with the controller  96 . The user interface  98  may include one or more knobs, dials, switches, displays, touch screens and the like for communicating with the user, such as to receive input and provide output. The user may enter different types of information including, without limitation, cycle selection and cycle parameters, such as cycle options. 
     The controller  96  may include the machine controller and any additional controllers provided for controlling any of the components of the washing machine  10 . For example, the controller  96  may include the machine controller and a motor controller. Many known types of controllers may be used for the controller  96 . The specific type of controller is not germane to the invention. It is contemplated that the controller is a microprocessor-based controller that implements control software and sends/receives one or more electrical signals to/from each of the various working components to effect the control software. As an example, proportional control (P), proportional integral control (PI), and proportional derivative control (PD), or a combination thereof, a proportional integral derivative control (PID control), may be used to control the various components. 
     As illustrated in  FIG. 2 , the controller  96  may be provided with a memory  100  and a central processing unit (CPU)  102 . The memory  100  may be used for storing the control software that is executed by the CPU  102  in completing a cycle of operation using the washing machine  10  and any additional software. Examples, without limitation, of cycles of operation include: wash, heavy duty wash, delicate wash, quick wash, pre-wash, refresh, rinse only, and timed wash. The memory  100  may also be used to store information, such as a database or table, and to store data received from one or more components of the washing machine  10  that may be communicably coupled with the controller  96 . For example, the current/power requirement for current drawing components may be stored in the memory  100 . The current/power threshold for the washing machine  10  may be also stored in the table in the form of factory default values. The database or table may be used to store the various operating parameters for the one or more cycles of operation, including factory default values for the operating parameters and any adjustments to them by the control system or by user input. 
     The controller  96  may be operably coupled with one or more components of the washing machine  10  for communicating with and controlling the operation of the component to complete a cycle of operation. For example, the controller  96  may be operably coupled with the motor  88 , the pump  74 , the dispenser  62 , the steam generator  82  and the sump heater  84  to control the operation of these and other components to implement one or more of the cycles of operation. 
     The controller  96  may also be coupled with one or more sensors  104  provided in one or more of the systems of the washing machine  10  to receive input from the sensors, which are known in the art and not shown for simplicity. Non-limiting examples of sensors  104  that may be communicably coupled with the controller  96  include: a temperature sensor  85 , a moisture sensor, a weight sensor, a chemical sensor, a position sensor, a motor torque sensor. 
     In one example, the motor torque sensor may be operably coupled to the controller  96  to provide the torque information to the controller  96 . The torque information may be provided to the controller  96  in the form of speed, current, voltage, or torque. For example, the amount of current drawn by the motor  88  for rotating the drum  14  at a speed may be received by the controller  96 , and then stored in the memory  100  of the controller  96 . 
     The power consumption of other current drawing components may be also separately provided to the controller  96 . For example, the signal from the temperature sensor  85  coupled to the sump heater  84  or steam generator  82  may be provided to the controller  96  to determine the power supplied to the heating elements of sump heater  84  or steam generator  82 . The pump  74  may be provided with a current or voltage sensor to determine the current or voltage information applied to the motor of the pump  74 . The controller  96  may convert the current, voltage, temperature or other signals that are received from each component to power consumption by executing the control software stored in the controller  96 . 
     It may be understood that in most cases the power consumption of washing machine  10  is directly related to the treating capacity of the washing machine  10 . Increasing the treating capacity of the washing machine  10  may require increased drum size, which necessitates higher motor torque and increase current/power consumption. While it may be required to replace a small torque motor with a higher torque motor for the washing machine  10  with high treating capacity, it may be noted the total power consumption of the washing machine  10  may also need to be considered. The washing machine may be typically provided with a maximum allowable current for operating the washing machine according to a cycle of operation. The maximum allowable current level may be determined for the washing machine such that summation of current drawn by all components of the washing machine need to be maintained below the maximum allowable current threshold to avoid tripping. For example, in the United States, where a 115V, 15 ampere electrical supply is common, 12 ampere may be set as the maximum current threshold that may be drawn for the washing machine from the circuit breaker for operating a cycle of operation of the washing machine. The 12 ampere maximum is below that of the supply and provides a suitable safety margin. However, higher maximums can be set. The maximum current, in most cases, will be dependent on the electrical supply. The 115V, 15 ampere example is for illustration only, and is not meant to be limiting. 
     Due to the maximum current/power threshold allowed for the washing machine  10 , when more current/power is drawn to a component, such as the motor, than is required, only reduced current/power resources may be available for remaining components. For example, if the motor  88  draws more current than is designed, only reduced amount of current may be available for the operation of another current drawing component to avoid tripping of a breaker for the electrical supply. 
     In the clothes washer, the heater, such as the sump heater  84 , is another component, like the motor  88 , which draws a relatively large amount of the available power under normal operating conditions to function properly. If it is necessary to supply reduced power to the sump heater  84  to avoid tripping of the breaker, the reduced heat output can significantly increase the time to heat the liquid supplied to the tub  14  up to a predetermined temperature for the selected cycle of operation, which can delay the whole cycle time and cause customer dissatisfaction. In another example, if only limited current is provided to the heater and fails to heat the laundry and/or liquid to the predetermined temperature, treating chemistry, which may be designed to treat laundry for a specific temperature range, may not properly treat laundry items as designed. 
     The invention addresses the problem by selectively operating the first and second heating elements in response to the amount of power being consumed by other components in the appliance  10 . As the motor  88  is the component that consumes a relative large amount of power, the specific example will be in the interplay between the power consumption of the heater  84  and the motor  88 . However, the invention is applicable to the interplay of the power consumption of any combination of power-consuming components of the appliance. 
     Looking at the specific example of the interplay between the heater  84  and the motor  88 , to avoid an excessive current draw that would otherwise trip the breaker during a cycle of operation, the first heating element is configured to be ON throughout the entire cycle of operation, while the second heating element is configured to be only ON while the motor  88  is turned OFF. Selectively operating one of the dual heating elements in response to the ON/OFF state of the motor  88  provides for controlling the total current/power consumption of the washing machine  10  to keep it below the maximum current/power threshold. 
       FIG. 3  illustrates a schematic heating cycle for the first and second heating elements with respect to the motor operation according to a second embodiment of the invention. While both first and second heating elements may belong to one heater such as the sump heater  84  or steam generator  82 , other configuration may be also possible. For example, the sump heater  84  may have the first heating element, and the steam generator  82  may have the second heating element. For illustrative purposes, the maximum power for the first and second heating element may be set as 700 watts, respectively. The power threshold of the washing machine  10  may be assumed to be 1450 watts, and the motor power for rotating the drum  14  at 50 rpm may be set as 700 watts. 
     The rotation of the motor  88  may be illustrated in motor speed profile  110 . As illustrated, the motor  88  may be turned on to rotate the drum  16  in one direction for a predetermined time period (section A), then the motor  88  is turned off (section B). The motor  88  then rotates the drum  16  in an opposite direction (section C) for a predetermined time period, and then the motor  88  is turned off again (section D). The motor  88  may repeat the alternating ON/OFF operations for a predetermined time period before the motor  88  receives a signal from the controller  96  to stop the operation. Irrespective of the rotational direction of the drum  16 , power consumption profile  111  for the drum  16  illustrates that the drum  16  may consume 700 watts for rotating the drum  16 . 
     The consumed power for the first and second heating elements is illustrated in power consumption profiles for the first and second heating elements,  112 ,  114 , respectively. When a heating cycle begins, first heating element may be configured to be ON state for an entire heating cycle. For example, the first heating element is continuously provided with 700 watts of power to provide thermal output to the laundry and/or liquid in the tub  14 , regardless of the operation of motor  88  and/or the second heating element. 
     The second heating element may be configured to change the ON/OFF state, alternately with the ON/OFF state of the motor  88 . For example, whenever the motor  88  is turned ON, the second heating element may be configured to turn OFF, and vice versa. 
     When the motor  88  is turned on, with the first heating element in the ON state (section A), the power consumption of the motor  88 , first heating element and second heating element may be sensed by the sensors such as the motor torque sensor or temperature sensor. The sensors may provide the controller  96  with sensor signals that may be indicative of the current/power consumed by each component. 
     The power consumption for each electric component may be added, and then compared with the current/power threshold stored in the controller  96  to prevent any tripping of the washing machine  10 . For example, while operating the motor  88  and the first heating element may require drawing 1400 watts, operating the motor  88 , the first and second heating elements may necessitates drawing 2100 watts, which is above the maximum power threshold  118  of 1450 watts. Therefore, power may be supplied only to the motor  88  and the first heating element to maintain the total power consumption  116  at 1400 watts, while the second heating element may be turned off. 
     When the motor  88  is turned off to stop rotating the drum  14  (section B), the power consumption may be determined again by the sensors and controller  96 . As the power consumption by the first and second heating element is calculated to be 1400 watts, which is less than the current/power threshold  118  of 1450 watts, the second heating elements is provided with current to increase the thermal output of the second heating element up to 700 watts for heating the laundry and/or liquid. In this case, the total power consumption  116  for first and second heating elements may be 1400 watts, which is below the current/power threshold  118  for the washing machine  10 , and still provides safety margin. 
     When the motor  88  begins to rotate in an opposite direction according to a cycle of operation (section C), the power consumed by the motor  88  and the first heating element may be determined, and then compared with the current/power threshold to adjust the operation of electric components as necessary. Similar to section A, the second heating element may be turned off to avoid tripping. 
     Section D, which is similar to section B, may follow section C. The heating cycle comprising sections A, B, C and D, may continue for a predetermined time period before the heating elements receives a signal from the controller  96  to stop heating. It may be understood that the ON/OFF switching for the second heating element may be conducted by providing one or more relays or triac to the control circuit for heating elements. 
       FIG. 3  illustrates that the current/power may be discretely applied to the component. For example, the power consumption profile  114  may illustrate that the power level applied to the second heating element discretely switches between zero to 700 watts. While the current/power may be discretely adjusted between any two levels, it may be noted that current/power may be applied to the electric component in a continuous way. For example, the power consumption profiles,  111 ,  112  and  114  may be in the form of sinusoid wave such that the current/power that is applied to the component may increase or decrease in a continuous way. 
     Applying the current/power continuously to a component alternately with another component may be advantageous in terms of fully utilizing the maximum current/power allowable for the washing machine  10 . For example, when the rotational speed of the motor  88  is configured to vary during the heating cycle, the power applied to the motor  88  may also vary. As the current/power threshold  118  is a fixed value for the washing machine  10 , another component, such as the second heating element, may be provided with variable current/power such that the power applied to the second heating element may continuously increase when the motor speed continuously decreases. On the other hand, when the motor power increases, the power applied to the second heating element may be configured to continuously decrease. As a result, irrespective of the variable power consumption of the motor  88  during a cycle of operation, the components may use almost 100% of maximum current/power allowable for the washing machine  10 , which may be advantageous in efficiently consuming power supplied to the washing machine  10 . 
     While the claimed invention is described for the interplay between the motor  88  and heating elements, any combination of other power-consuming components for the washing machine  10  may be operably coupled to each other for controllably vary the power consumption level of the components. The non-limiting examples of other power-consuming components include interior lights, exterior lights, user interface, printed circuit board, memory, processor or the like. In one embodiment, one or more power-consuming components may be operably coupled to the motor  88 , for selective ON/OFF cycling of one or more power-consuming components, depending on the ON/OFF cycling of the motor  88 . In another embodiment, one or more power-consuming components may be operably coupled to the motor  88  and the heating elements for selectively varying the power consumption level of one or more power-consuming components. Selectively varying the power consumption level may include either discretely or continuously varying the power consumption level. Operating the laundry treating machine with all of the power drawing components coupled for selectively varying the power consumption levels of each component may be advantageous in further fully utilizing the power available for the laundry treating appliance. 
     To the extent not already described, the different features and structures of the various embodiments may be used in combination with each other as desired. That one feature may not be illustrated in all of the embodiments is not meant to be construed that it cannot be, but is done for brevity of description. Thus, the various features of the different embodiments may be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. 
     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. Reasonable variation and modification are possible within the scope of the forgoing disclosure and drawings without departing from the spirit of the invention which is defined in the appended claims.