Abstract:
A method for detecting an oversuds condition that can lead to a suds lock condition in a laundry treating appliance includes determining a baseline fill level prior to introducing wash liquid in the cycle of operation; sampling fill levels of the wash liquid during a wash phase of the cycle of operation while wash liquid is being drained; comparing each sampled fill level to the baseline fill level and determining a difference; continuing to sample fill levels for a predetermined period after the difference equals zero; identifying a minimum fill level for the predetermined period; sampling a final fill level after the predetermined period; calculating a difference between the minimum fill level and the final fill level; and identifying a potential suds lock condition if the difference exceeds a predetermined threshold.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Laundry treating appliances, such as clothes washers, typically include a tub in which is mounted a rotatable wash basket which receives laundry for treatment according to a cycle of operation. In a typical wash cycle, the laundry is often treated with a laundry detergent or other wash aid that includes surfactants. These surfactants may mix with liquid on the laundry and in the tub to generate suds. In some cases, the generation of suds may generate a suds lock condition and interfere with the rotation of the wash basket, thereby limiting the speed at which the wash basket may be rotated. 
       BRIEF DESCRIPTION 
       [0002]    A method for detecting an oversuds condition that may lead to a suds lock condition in a laundry treating appliance having a tub defining an interior, with a wash basket rotatably mounted within the interior and at least partially defining a treating chamber for receiving laundry for treatment in accordance with a cycle of operation using a wash liquid. The method comprises determining a baseline fill level in the treating chamber prior to introducing wash liquid into the treating chamber in the cycle of operation; sampling fill levels of the wash liquid in the treating chamber during a wash phase of the cycle of operation while wash liquid is being drained from the treating chamber; comparing each sampled fill level to the baseline fill level and determining a difference; continuing to sample fill levels in the treating chamber for a predetermined period after the difference equals zero; identifying a minimum fill level in the treating chamber for the predetermined period; sampling a final fill level after the predetermined period; calculating a difference between the minimum fill level and the final fill level; and identifying an over suds condition that can lead to a suds lock condition if the difference exceeds a predetermined threshold. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a schematic cross-sectional view of a laundry treating appliance according to one embodiment of the invention. 
           [0004]      FIG. 2  is a schematic view of a controller of the laundry treating appliance of  FIG. 1 . 
           [0005]      FIG. 3  is a flowchart illustrating a method for detecting an over suds condition according to an embodiment of the invention. 
           [0006]      FIG. 4  is a graphical representation of a treating chamber fill level profile according to an embodiment of the invention. 
       
    
    
     DESCRIPTION 
       [0007]    Referring now to the figures,  FIG. 1  is a schematic view of an exemplary laundry treating appliance  10  in the form of a washing machine according to one embodiment of the invention. While the laundry treating appliance  10  is illustrated as a vertical axis, top-fill washing machine, the invention may have applicability in other laundry treating appliances, such as a horizontal washing machine, combination laundry treating appliance and dryer, an extractor, a non-aqueous laundry treating appliance, and a tumbling or stationary refreshing/revitalizing machine, for example. 
         [0008]    The washing machine  10  may include a cabinet or housing  12  and an imperforate tub  14  that defines an interior  15  of the washing machine  10 . A sump  16  may be in fluid communication with the interior  15  of the tub  14 . A drum or perforated wash basket  18  may be located within and rotatable relative to the interior  15  of the tub  14  and may define a laundry treating chamber  19  for receiving a laundry load. The wash basket  18  may include a plurality of perforations or apertures (not shown) such that liquid supplied to the wash basket  18  may flow through the perforations to the tub  14 . An agitator or clothes mover  20  may be located within the laundry treating chamber  19  and rotatable relative to and/or with the wash basket  18 . 
         [0009]    The wash basket  18  and/or the clothes mover  20  may be driven by an electrical motor  22 , which may or may not include a gear case, operably connected to the wash basket  18  and/or the clothes mover  20 . The clothes mover  20  may be commonly oscillated or rotated about its axis of rotation during a cycle of operation in order to produce high water turbulence effective to treat the fabric load contained within the laundry treating chamber  19 . The wash basket  18  may be rotated at high speed to centrifugally extract liquid from the fabric load and to discharge it from the wash basket  18 . The top of the housing  12  may include a selectively openable lid  24  to provide access into the laundry treating chamber  19  through the open top of the wash basket  18 . 
         [0010]    Still referring to  FIG. 1 , a spraying system  30  may be provided to spray liquid, such as water or a combination of water and one or more treating agents into the open top of the wash basket  18  and onto laundry placed within the laundry treating chamber  19 . 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, surfactants, 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. 
         [0011]    The spraying system  30  may be configured to supply water directly from a household water supply  32  and/or from the tub  14  and spray it onto the laundry through a sprayer  33 . The spraying system  30  may also be configured to recirculate wash water from the tub  14 , including the sump  16 , and spray it onto the laundry. The spraying system  30  can also include additional sprayers and other components to supply liquid to one or more additional locations, such as a portion of the interior  15  between the wash basket  18  and the tub  14 , an exterior surface of the wash basket  18 , an interior surface of the wash basket  18  and an internal surface of the tub  14 . The nature of the spraying system is not germane to the invention, and thus any suitable spraying system may be used with the laundry treating appliance  10 . 
         [0012]    A pump  34  may be housed below the tub  14 . The pump  34  may have an inlet fluidly coupled to the sump  16  and an outlet configured to fluidly couple to either or both a household drain  36  or a recirculation conduit  38 . In this configuration, the pump  34  may be used to drain or recirculate liquid in the sump  16 , which is initially sprayed into the wash basket  18 , flows through the wash basket  18 , and then into the sump  16 . Alternatively, two separate pumps may be used instead of the single pump as previously described. 
         [0013]    As used herein, the term wash liquid refers to a combination of water and one or more treating agents capable of generating suds. The terms rinse liquid and rinse water are interchangeable and refer to water supplied from the household water supply  32  that has not been mixed with a treating agent prior to being applied to the laundry. The terms recirculated liquid and recirculated water refer to water or a combination of water and one or more treating agents that is pumped from the sump  16  and re-applied to the laundry, with or without the addition of additional rinse liquid from the household water supply  32 . 
         [0014]    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  60  located within the cabinet  12  and a user interface  62  that is operably coupled with the controller  60 . The user interface  62  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. 
         [0015]    The controller  60  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  60  may include the machine controller and a motor controller. Many known types of controllers may be used for the controller  60 . The specific type of controller is not germane to the invention. It is contemplated that the controller  60  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. 
         [0016]    As illustrated in  FIG. 2 , the controller  60  may be provided with a memory  70  and a central processing unit (CPU)  72 . The memory  70  may be used for storing the control software that is executed by the CPU  72  in implementing 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. A common wash cycle includes a wash phase, a rinse phase, and a spin extraction phase. Other phases for cycles of operation include, but are not limited to, intermediate extraction phases, such as between the wash and rinse phases, and a pre-wash phase preceding the wash phase, and some cycles of operation include only a select one or more of these exemplary phases. 
         [0017]    The memory  70  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  60 . 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. 
         [0018]    The controller  60  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  60  may be operably coupled with the motor  22 , the pump  34 , and the spraying system  30  to control the operation of these and other components to implement one or more of the cycles of operation. 
         [0019]    The previously described washing machine  10  may be used to implement one or more embodiments of the invention. The embodiments of the method of the invention may be used to control the operation of the washing machine  10  to detect the formation of surfactant foam or suds in the tub  14  to mitigate a potential suds lock condition. As used herein, mitigating a suds lock condition may include decreasing the formation of suds and/or removing suds from the tub  14  such that a suds lock condition is avoided or the effect of the suds on the tub  14  and wash basket  18  is decreased. 
         [0020]    A typical wash cycle includes a wash phase in which a wash liquid, e.g., a mixture of water and surfactants (and optionally other treating agents), is applied to the laundry, a rinse phase in which the wash liquid is removed from the laundry by rinsing the laundry with rinse liquid, and a spin extraction phase in which at least a portion of the rinse liquid is extracted from the laundry by spinning the laundry at high speeds. A suds lock condition occurs when the wash liquid forms suds and the suds interact with the wash basket  18  and tub  14 , causing excess frictional drag between the wash basket  18  and the tub  14 . The excess frictional drag may inhibit the wash basket  18  from accelerating to a desired wash basket rotation speed, such as a final or spin extraction rotation speed in which the laundry is rotated at high speeds to extract liquid from the laundry. The methods described herein may be used to detect an over suds condition that can lead to a suds lock condition prior to the rinse phase. 
         [0021]    Referring now to  FIG. 3 , a flowchart of a method  100  for detecting an over suds condition during a cycle of operation is illustrated. The method  100  may be used during a wash cycle or any other cycle of operation in which wash liquid has been applied to the laundry. The method  100  may be implemented as part of a wash or rinse phase of a wash cycle or may be implemented as a separate phase. The sequence of steps depicted for this method is for illustrative purposes only, and is not meant to limit the method in any way as it is understood that the steps may proceed in a different logical order or additional or intervening steps may be included without detracting from the invention. 
         [0022]    The method  100  starts with assuming that a cycle of operation in which a wash liquid is applied to the laundry in the treating chamber  19 , such as a wash cycle, has not yet been implemented. At  102 , the controller  60  implementing the method  100  may measure a baseline fill level in the treating chamber  19 . The baseline fill level is the initial level of liquid in the treating chamber  19  before wash liquid is introduced for the cycle of operation. The controller  60  may monitor the fill level of the wash liquid in the treating chamber  19  by sampling a sensor such as a pressure transducer (not shown) located in the treating chamber  19 . An example pressure transducer and sampling rate that may be used is the Panasonic ADP51B62 sampled once every 63 ms. Other fluid level sensing technologies and sampling rates may be used depending upon the implementation. 
         [0023]    At  104 , the fill and wash steps of the cycle of operation may be completed. During these steps, wash liquid may be introduced in the treating chamber  19 . 
         [0024]    At  106 , the pump  34  may drain the wash liquid from the treating chamber  19 . The operation of draining the treating chamber  19  may continue until the processor  60  determines the treating chamber  19  is empty. The controller  60  may determine that the treating chamber  19  is empty by sampling the fill level of the treating chamber  19  as the wash liquid is being drained and comparing the sampled fill level to the baseline fill level from  102 . When the sampled fill level is less than or equal to the baseline fill level from  102 , the controller  60  may consider the treating chamber  19  to be empty. 
         [0025]    Once the difference between the sampled fill level and the baseline fill level is zero, the controller  60  may start a timer at  108  for a predetermined period. The predetermined time period may be determined by the particular physical characteristics of an implementation of the washer. A predetermined time period of 60 seconds may be used but other predetermined time periods are possible depending upon the specific implementation. 
         [0026]    For the duration of the predetermined time period, the controller  60  may sample the fill level of the treating chamber  19  and store the minimum fill level. The controller  60  may make a check to determine if the predetermined time period has expired at  110 , and if it has not, may determine if the currently sampled fill level is less than the current minimum fill level for the predetermined time period. If the currently sampled fill level is less than the current minimum fill level for the predetermined time period, then the controller  60  may update the stored minimum fill level for the predetermined time period to be the currently sampled fill level at  112 . By repeating the steps at  110  and  112  until the expiration of the predetermined time period at  110 , the controller  60  may determine the minimum fill level in the treating chamber  19  for the predetermined time period. After the predetermined time period has expired, the controller  60  may stop draining the treatment chamber  19  at  114  and sample a final fill level at  116 . 
         [0027]    At  118 , the controller  60  may calculate the difference between the minimum fill level and the final fill level by subtracting the minimum fill level during the predetermined time period from the final fill level. If the difference is greater than a predetermined threshold as calculated at  120 , the controller  60  may identify at  122  that a suds lock condition may occur due to an excessive amount of suds. The predetermined threshold may be determined by the particular physical characteristics of an implementation of the washer. 
         [0028]    The controller  60  may then take action at  124  to mitigate or avoid a suds lock condition. For example, upon the identification of a potential suds lock condition, the controller  60  may rotate the wash basket in a progressive rinse phase of the wash cycle. The controller  60  may take other actions to mitigate the potential suds lock condition depending upon the specific implementation. 
         [0029]    If, at  120 , the difference is not greater than a predetermined threshold, the controller  60  may not identify a potential suds lock condition at  126 . The controller  60  may then continue to a normal phase of the cycle of operation at  128 . For example, the controller  60  may rotate the wash basket in a deep rinse phase of the wash cycle. 
         [0030]    Referring now to  FIG. 4 , an exemplary treating chamber fill level profile  200  is illustrated. The treating chamber fill level profile  200  illustrates the fill level of the treating chamber  19  during implementation of the method  100  of  FIG. 3  in the course of a cycle of operation. The treating chamber fill level profile  200  may not be indicative of actual data, but is included for the purposes of illustration. 
         [0031]      FIG. 4  illustrates the drain phase of a wash cycle  200  where excessive suds that may lead to a suds lock condition may be present. The profile shown is digital counts of a pressure sensor indicating fill level of a treating chamber  19  versus time in seconds. The fill level is shown to be decreasing at  202  as the treating chamber  19  drains. At  204 , the controller  60  may determine the treating chamber is empty and records a baseline fill level. The controller  60  may then continue to sample the fill level for a predetermined period of time and record the minimum fill level at  206 . When the predetermined period of time ends, the controller  60  may sample a final fill level and compare to the minimum fill level. If the controller  60  determines the minimum fill level at  206  is below the final fill level by a predetermined threshold, it may identify excessive suds that may lead to an suds lock condition and take appropriate action to mitigate or avoid a suds lock condition. 
         [0032]    The methods described herein may be used to detect and mitigate the formation of a suds lock condition in a washing machine. Excess suds in a washing machine may increase the frictional drag between the wash basket and the tub, which may result in the wash basket not reaching a desired rotational speed or may require additional energy to reach the desired rotation speed, which may increase energy costs during the cycle. During a spin extraction phase, the wash basket is rotated at high speeds to remove liquid from the laundry for subsequent treatment or drying. If the wash basket cannot be rotated at the desired spin extraction speed due to a suds lock condition, it may take longer to extract liquid from the laundry, which may provide an undesirable lengthening of the cycle, or the laundry may maintain more liquid at the end of the cycle, which may be undesirable to the user. The methods described herein may be used to identify a potential suds lock condition before it occurs and decrease the interaction between the tub and the wash basket during rotation of the wash basket. 
         [0033]    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. 
         [0034]    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.