Abstract:
A controller for a washing machine including an agitation element operable at a plurality of speeds during an agitation phase of a wash cycle is provided. The controller comprises a microcomputer configured to adjust an actuation of the agitation element in response to at least one input, said at least one input indicative of a characteristic of a laundry load.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to washing machines, and, more particularly, to methods and apparatus for controlling agitation time and agitation speed during agitation phases of wash cycles. 
   Washing machines typically include a cabinet that houses an outer tub for containing wash and rinse water, a perforated clothes basket within the tub, and an agitator within the basket. A drive and motor assembly is mounted underneath the stationary outer tub to rotate the clothes basket and the agitator relative to one another, and a pump assembly pumps water from the tub to a drain to execute a wash cycle. See, for example, U.S. Pat. No. 6,029,298. 
   Periodically as the washing machine is used, the agitator is actuated by a control mechanism and imparts an oscillatory motion to articles and liquid in the basket, thereby producing mechanical washing action and energy to clean articles in the basket. Traditionally, the agitator is actuated for a fixed time period and at a fixed, predetermined actuation speed or intensity during agitation phases of a wash cycle. For certain laundry loads, however, the agitation speed and/or the agitation duration may be excessive. Aside from energy considerations associated with unnecessary agitation, excessive agitation extends the time for the wash cycle to complete and can lead to excessive wear of laundered articles washed in the machine. 
   BRIEF DESCRIPTION OF THE INVENTION 
   In one aspect, a controller for a washing machine including an agitation element operable at a plurality of speeds during an agitation phase of a wash cycle is provided. The controller comprises a microcomputer configured to adjust an actuation of the agitation element in response to at least one input, said at least one input indicative of a characteristic of a laundry load. 
   In another aspect, an agitation phase control system for a washing machine is provided. The control system comprises a drive system comprising an agitation element, and a controller operatively coupled to said drive system. The controller is configured to vary operation of said agitation element in response to laundry load characteristics. 
   In another aspect, a washing machine is provided. The washing machine comprises a cabinet, a basket mounted within said cabinet, an agitation element mounted within said basket, and a drive system coupled to said agitation element. The drive system is configured to move said agitation element in an oscillatory manner at a plurality of speeds. A controller is operatively coupled to said drive system, and the controller comprises a microcomputer and a memory, and the memory comprises a plurality of agitation time values and a plurality of agitation speed values. The microcomputer is configured to select one of said agitation time values and one of said agitation speed values in response to laundry load inputs. 
   In another aspect, a method for controlling a washing machine in an agitation phase of a wash cycle is provided. The washing machine includes an agitation element therein and a controller operatively coupled thereto, and the method comprises accepting at least one laundry load input, and operating the agitation element at one of a plurality of settings based upon the laundry load input. 
   In still another aspect, a method for controlling a washing machine in an agitation phase of a wash cycle is provided. The washing machine includes a multi-speed drive system coupled to an agitation element and a controller operatively coupled to the drive system. The method comprises accepting a laundry soil level input, selecting one of a plurality of agitation time parameter settings in response to said soil level input, accepting a laundry load size input, selecting one of a plurality of agitation speed parameter settings in response to said load size input, and operating the drive system in accordance with the selected agitation time parameter setting and the selected agitation speed parameter setting. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective cutaway view of an exemplary washing machine. 
       FIG. 2  is front elevational schematic view of the washing machine shown in  FIG. 1 . 
       FIG. 3  is a schematic block diagram of a control system for the washing machine shown in  FIGS. 1 and 2 . 
       FIG. 4  is a washer agitation control algorithm executable by the controller shown in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a perspective view partially broken away of an exemplary washing machine  50  including a cabinet  52  and a cover  54 . A backsplash  56  extends from cover  54 , and a control panel  58  including a plurality of input selectors  60  is coupled to backsplash  56 . Control panel  58  and input selectors  60  collectively form a user interface input for operator selection of machine cycles and features, and in one embodiment a display  61  indicates selected features, a countdown timer, and other items of interest to machine users. A lid  62  is mounted to cover  54  and is rotatable about a hinge (not shown) between an open position (not shown) facilitating access to a wash tub  64  located within cabinet  52 , and a closed position (shown in  FIG. 1 ) forming a sealed enclosure over wash tub  64 . As illustrated in  FIG. 1 , machine  50  is a vertical axis washing machine. 
   Tub  64  includes a bottom wall  66  and a sidewall  68 , and a basket  70  is rotatably mounted within wash tub  64 . A pump assembly  72  is located beneath tub  64  and basket  70  for gravity assisted flow when draining tub  64 . Pump assembly  72  includes a pump  74  and a motor  76 . A pump inlet hose  80  extends from a wash tub outlet  82  in tub bottom wall  66  to a pump inlet  84 , and a pump outlet hose  86  extends from a pump outlet  88  to an appliance washing machine water outlet  90  and ultimately to a building plumbing system discharge line (not shown) in flow communication with outlet  90 . 
     FIG. 2  is a front elevational schematic view of washing machine  50  including wash basket  70  movably disposed and rotatably mounted in wash tub  64  in a spaced apart relationship from tub side wall  64  and tub bottom  66 . Basket  12  includes a plurality of perforations therein to facilitate fluid communication between an interior of basket  70  and wash tub  64 . 
   A hot liquid valve  102  and a cold liquid valve  104  deliver fluid, such as water, to basket  70  and wash tub  64  through a respective hot liquid hose  106  and a cold liquid hose  108 . Liquid valves  102 ,  104  and liquid hoses  106 ,  108  together form a liquid supply connection for washing machine  50  and, when connected to a building plumbing system (not shown), provide a fresh water supply for use in washing machine  50 . Liquid valves  102 ,  104  and liquid hoses  106 ,  108  are connected to a basket inlet tube  110 , and fluid is dispersed from inlet tube  110  through a known nozzle assembly  112  having a number of openings therein to direct washing liquid into basket  70  at a given trajectory and velocity. A known dispenser (not shown in  FIG. 2 ), may also be provided to produce a wash solution by mixing fresh water with a known detergent or other composition for cleansing of articles in basket  70 . 
   In an alternative embodiment, a known spray fill conduit  114  (shown in phantom in  FIG. 2 ) may be employed in lieu of nozzle assembly  112 . Along the length of the spray fill conduit  114  are a plurality of openings arranged in a predetermined pattern to direct incoming streams of water in a downward tangential manner towards articles in basket  70 . The openings in spray fill conduit  114  are located a predetermined distance apart from one another to produce an overlapping coverage of liquid streams into basket  70 . Articles in basket  70  may therefore be uniformly wetted even when basket  70  is maintained in a stationary position. 
   A known agitation element  116 , such as a vane agitator, impeller, auger, or oscillatory basket mechanism, or some combination thereof is disposed in basket  70  to impart an oscillatory motion to articles and liquid in basket  70 . In different embodiments, agitation element  116  may be a single action element (i.e., oscillatory only), double action (oscillatory movement at one end, single direction rotation at the other end) or triple action (oscillatory movement plus single direction rotation at one end, singe direction rotation at the other end). As illustrated in  FIG. 2 , agitation element  116  is oriented to rotate about a vertical axis  118 . 
   Basket  70  and agitator  116  are driven by motor  120  through a transmission and clutch system  122 . A transmission belt  124  is coupled to respective pulleys of a motor output shaft  126  and a transmission input shaft  128 . Thus, as motor output shaft  126  is rotated, transmission input shaft  128  is also rotated. Clutch system  122  facilitates driving engagement of basket  70  and agitation element  116  for rotatable movement within wash tub  64 , and clutch system  122  facilitates relative rotation of basket  70  and agitation element  116  for selected portions of wash cycles. Motor  120 , transmission and clutch system  122  and belt  124  collectively are referred herein as a machine drive system. As will be appreciated below, the motor drive system is a multiple speed drive in that it is capable of operating agitation elements at different speeds to optimize the wash cycle agitation phase. 
   Washing machine  50  also includes a brake assembly (not shown) selectively applied or released for respectively maintaining basket  70  in a stationary position within tub  64  or for allowing basket  70  to spin within tub  64 . Pump assembly  72  is selectively activated to remove liquid from basket  70  and tub  64  through drain outlet  90  and a drain valve  130  during appropriate points in washing cycles as machine  50  is used. In an exemplary embodiment, machine  50  also includes a reservoir  132 , a tube  134  and a pressure sensor  136 . As fluid levels rise in wash tub  64 , air is trapped in reservoir  132  creating a pressure in tube  134  that pressure sensor  136  monitors. Liquid levels, and more specifically, changes in liquid levels in wash tub  64  may therefore be sensed, for example, to indicate laundry loads and to facilitate associated control decisions. In further and alternative embodiments, load size and cycle effectiveness may be determined or evaluated using other known indicia, such as motor spin, torque, load weight, motor current, voltage or current phase shifts, etc. 
   Operation of machine  50  is controlled by a controller  138  which is operatively coupled to the user interface input located on washing machine backsplash  56  (shown in  FIG. 1 ) for user manipulation to select washing machine cycles and features. In response to user manipulation of the user interface input, controller  138  operates the various components of machine  50  to execute selected machine cycles and features. 
   In an illustrative embodiment, clothes are loaded into basket  70 , and washing operation is initiated through operator manipulation of control input selectors  60  (shown in  FIG. 1 ). Tub  64  is filled with water and mixed with detergent to form a wash fluid, and basket  70  is agitated with agitation element  116  for cleansing of clothes in basket  70 . That is, agitation element is moved back and forth in an oscillatory back and forth motion. In the illustrated embodiment, agitation element  116  is rotated clockwise a specified amount about the vertical axis of the machine, and then rotated counterclockwise by a specified amount. The clockwise/counterclockwise reciprocating motion is sometimes referred to as a stroke, and the agitation phase of the wash cycle constitutes a number of strokes in sequence. Acceleration and deceleration of agitation element  116  during the strokes imparts mechanical energy to articles in basket  70  for cleansing action. The strokes may be obtained in different embodiments with a reversing motor, a reversible clutch, or other known reciprocating mechanism. 
   As explained further below, and unlike convention machines utilizing a fixed stroke rate (i.e., number of strokes per unit time) and a fixed time period in the agitation phase, the present invention accommodates adjustment of the stroke rate and the agitation time period to optimize the agitation phases of wash cycles. Optimization of the agitation phases reduces wear on clothes and reduces energy consumption by the machine. 
   After the agitation phase of the wash cycle is completed, tub  64  is drained with pump assembly  72 . Clothes are then rinsed and portions of the cycle repeated, including the agitation phase, depending on the particulars of the wash cycle selected by a user. 
     FIG. 3  is a schematic block diagram of an exemplary washing machine control system  150  for use with washing machine  50  (shown in  FIGS. 1 and 2 ). Control system  150  includes controller  138  which may, for example, be a microcomputer  140  coupled to a user interface input  141 . An operator may enter instructions or select desired washing machine cycles and features via user interface input  141 , such as through input selectors  60  (shown in  FIG. 1 ) and a display or indicator  61  coupled to microcomputer  140  displays appropriate messages and/or indicators, such as a timer, and other known items of interest to washing machine users. A memory  142  is also coupled to microcomputer  140  and stores instructions, calibration constants, and other information as required to satisfactorily complete a selected wash cycle. Memory  142  may, for example, be a random access memory (RAM). In alternative embodiments, other forms of memory could be used in conjunction with RAM memory, including but not limited to flash memory (FLASH), programmable read only memory (PROM), and electronically erasable programmable read only memory (EEPROM). 
   Power to control system  150  is supplied to controller  138  by a power supply  146  configured to be coupled to a power line L. Analog to digital and digital to analog converters (not shown) are coupled to controller  138  to implement controller inputs and executable instructions to generate controller output to washing machine components such as those described above in relation to  FIGS. 1 and 2 . More specifically, controller  138  is operatively coupled to machine drive system  148  (e.g., motor  120 , clutch system  122 , and agitation element  116  shown in  FIG. 2 ), a brake assembly  151  associated with basket  70  (shown in  FIG. 2 ), machine water valves  152  (e.g., valves  102 ,  104  shown in  FIG. 2 ) and machine drain system  154  (e.g., drain pump assembly  72  and/or drain valve  130  shown in  FIG. 2 ) according to known methods. In a further embodiment, water valves  152  are in flow communication with a dispenser  153  (shown in phantom in  FIG. 3 ) so that water may be mixed with detergent or other composition of benefit to washing of garments in wash basket  70 . 
   In response to manipulation of user interface input  141  controller  138  monitors various operational factors of washing machine  50  with one or more sensors or transducers  156 , and controller  138  executes operator selected functions and features according to known methods. Of course, controller  138  may be used to control washing machine system elements and to execute functions beyond those specifically described herein. 
   Controller  138  operates the various components of washing machine  50  in a designated wash cycle familiar to those in the art of washing machines. However, and unlike known washing machines, controller  138  executes optimized agitation phases in wash cycles for actuation of agitation element  116  (shown in  FIG. 2 ). Excessive agitation of clothes may therefore be minimized, thereby reducing associated wear on clothes, and energy consumption required by the agitation phase. Agitation phases of the wash cycle may be adjusted for selected or detected load sizes, types, and characteristics as further described below. 
     FIG. 4  is an exemplary washer agitation control method in the form of an algorithm  170  executable by controller  138  (shown in  FIG. 3 ) for achieving optimal agitation of articles in basket  70  (shown in  FIGS. 1 and 2 ). Algorithm  170  may be a user selected option, such as through user manipulation of one of input selectors  60  (shown in  FIG. 1 ), or may be automatically activated or deactivated by machine controls in various embodiments. 
   The methodology set forth below recognizes that effectiveness of a wash cycle agitation phase is primarily dependant upon two parameters, an amount of chemical cleansing action and an amount of mechanical cleansing action. While the chemical cleansing action is partly dependent upon the soil level of articles to be washed, detergent compositions and compositions of any additives utilized in the wash cycle, the primary machine parameter that contributes to chemical cleansing action in the agitate phase is the agitate time duration. In other words, chemical cleansing action in the agitate phase of a wash cycle is a function of the agitation time. Thus, chemical cleansing action may be approximated by the relationship:
 
SR C ∝t agitate    (1)
 
where SR C  is the chemical cleansing action and t agitate  is the agitate time period.
 
   The mechanical cleansing action is partly dependant upon many machine parameters, but is primarily influenced by three parameters: the agitate time period, the amount of mechanical energy introduced into the basket during agitation, and the size of the laundry load. Therefore, it may be seen that the mechanical action is approximated by the relationship: 
                   SR   m     ∝       t   agitate     *       E     Agitate   Load       Load               (   2   )               
where SR m  is the mechanical cleansing action, t agitate  is the agitation time period, E Agitate     Load    is the mechanical energy input by drive system  151  (shown in  FIG. 3 ) during the agitate phase, and Load is the size of the load to be washed. The Load may be indicated by a selected or detected load size input (e.g., small, medium, large).
 
   Considering the mechanical energy input E Agitate     Load    it may be deduced that the primary machine parameter affecting the energy input is the speed or intensity of the agitate phase of the wash cycle. In other words, the rate of oscillatory strokes (i.e., oscillatory movements per unit time) primarily determines the mechanical energy input to clothes or laundry articles. It is therefore evident that the mechanical energy input is a function of agitation speed, and that the mechanical energy input may be approximated by the relationship:
 
E Agitate     Load   ∝N Agitate    (3)
 
where N Agitate  is the agitation speed.
 
   Inspection of equations (1) through (3) and substitution of Equation (3) into equation (2) reveals that: 
                   SR   m     ∝       t   agitate     *         N   Agitate     Load     .               (   4   )               
Now comparing Equations (1) and (4), it is apparent that mechanical action and chemical action are each a function of the agitate time duration, but only mechanical actuation is a function of the agitation speed and the load size. Therefore, the agitate phase of the wash cycle can be controlled by making control decisions based upon the parameters that have the greatest overall effect on agitate cycle efficacy.
 
   In one embodiment, controller  138  (shown in  FIG. 3 ), through algorithm  170  makes control decisions for agitation phases of wash cycles based upon characteristics of the laundry load to be washed in machine  50  (shown in  FIG. 1 ). Specifically, and in an exemplary embodiment, controller  138  adjusts agitation parameters based upon the laundry load size and the soil level of the laundry load. The soil level of the laundry affects the time duration of the agitation phase to optimize chemical cleansing action, and the load size affects the agitation speed or intensity of agitation element  116  (shown in  FIG. 2 ) to optimize mechanical cleansing action. 
   In an exemplary embodiment, algorithm  170  begins by accepting agitation inputs  174  that affect the agitation phase of the wash cycle. Inputs may be accepted through input selectors  60  (shown in  FIG. 1 ) and stored into controller memory  142  for later use when the agitation phase or portion of the wash cycle is commanded. In a further embodiment, controller  138 , or more specifically microcomputer  140 , may prompt a user for required inputs on display  61  (shown in  FIGS. 1 and 3 ). 
   Once inputs are accepted  174 , microcomputer  140  determines  176  whether the inputs include a SOIL LEVEL parameter. If the inputs do not include a SOIL LEVEL parameter, in one embodiment algorithm  170  returns to accept  174  additional inputs. 
   In a further and/or alternative embodiment controller  138  may retrieve  177  (shown in phantom in  FIG. 4 ) a default soil level parameter from controller memory  142  if no direct soil level input is made by a machine user, or if a soil level input is not received within a predetermined time period. The default parameter may be associated with a particular wash cycle selected by the user, or may be independent of the selected wash cycle. 
   In another further and/or alternative embodiment, controller  138  may detect  178  (shown in phantom in  FIG. 4 ) a soil level in the laundry load by known methods and techniques, including but not limited to the use of turbidity sensors and the like to monitor soil level of the water in the machine during use. 
   If a SOIL LEVEL parameter has been accepted  174 , controller sets  180  agitation time or agitation duration according to the input SOIL LEVEL parameter. For example, in an illustrative embodiment, control system  150  (shown in  FIG. 3 ) includes four SOIL LEVEL setting parameters, namely a light soil setting, a medium soil setting, a heavy soil setting, and a stain soil setting. Depending upon which of the soil level settings is selected, controller  138  sets an appropriate agitation time value corresponding to the selected setting. In general, as the accepted soil setting increases, the agitation duration increases to improve chemical cleansing action and to remove the soil, and as the accepted soil setting decreases the agitation duration decreases. Actual agitation time values may be calculated according to the above relationships or empirically determined for each of the available soil level settings. For instance, an exemplary agitation time versus soil level table for a load of cotton garments is set forth below in Table 1. 
   
     
       
             
             
             
           
         
             
                 
               TABLE 1 
             
             
                 
                 
             
             
                 
               SOIL LEVEL SETTING 
               AGITATION DURATION 
             
             
                 
                 
             
           
           
             
                 
               Light 
                9 minutes 
             
             
                 
               Medium 
               12 minutes 
             
             
                 
               Heavy 
               15 minutes 
             
             
                 
               Stain 
               18 minutes 
             
             
                 
                 
             
           
        
       
     
   
   A control lookup table, such as Table 1, may be stored in controller memory  142  (shown in  FIG. 3 ) so that microcomputer  140  may select the appropriate time duration value for the selected soil level setting. Chemical cleansing action during agitation portions is therefore substantially optimized. 
   To improve the mechanical cleansing action of the agitation phase of a wash cycle, and further according to algorithm  170 , controller  138  determines  192  whether a load size input has been accepted  174 . If the inputs do not include a LOAD SIZE parameter, in one embodiment algorithm  170  returns to accept  174  additional inputs. 
   In a further and/or alternative embodiment controller  138  may retrieve  184  (shown in phantom in  FIG. 4 ) a default load size parameter from controller memory  142  if no direct load size input is made by a machine user, or if a load size input is not received within a predetermined time period. The default parameter may be associated with a particular wash cycle selected by the user, or may be independent of the selected wash cycle. 
   In another further and/or alternative embodiment, controller  138  may detect  186  (shown in phantom in  FIG. 4 ) a laundry load size according to known methods and techniques. Load size may be inferred from an implicit measurement of machine operation, such as operating pressure via pressure sensor  136  (shown in  FIG. 2 ), spin torque, motor current, load weight, level sensors, voltage and/or current phase shifts, spin acceleration rates, brake stop time, or other known indicia of load size during wash operations. 
   If a LOAD SIZE input parameter has been accepted  174 , controller sets  188  agitation speed or intensity according to the accepted LOAD SIZE parameter. For example, in an illustrative embodiment, control system  150  (shown in  FIG. 3 ) includes five LOAD SIZE setting parameters, namely an extra small load size setting, a small load size setting, a medium load size setting, a large load size setting, and a giant load size setting. Depending upon which of the load size settings is selected, controller  138  sets an appropriate agitation speed value corresponding to the selected load size setting. As the load size setting increases, the agitation speed increases to improve mechanical cleansing action during the agitation phase, and as the load size setting decreases the agitation speed decreases. Actual agitation speed or intensity values may be calculated according to the above relationships or may be empirically determined for each of the available load size settings. For instance, an exemplary agitation speed versus load size table for a load of cotton garments is set forth below in Table 1. 
   
     
       
             
             
             
           
         
             
                 
               TABLE 2 
             
             
                 
                 
             
             
                 
                 
               AGITATION SPEED 
             
             
                 
               LOAD SIZE SETTING 
               (strokes per minute) 
             
             
                 
                 
             
           
           
             
                 
               Extra Small 
               100 
             
             
                 
               Small 
               130 
             
             
                 
               Medium 
               140 
             
             
                 
               Large 
               155 
             
             
                 
               Giant 
               155 
             
             
                 
                 
             
           
        
       
     
   
   A control lookup table, such as Table 2, may be stored in controller memory  142  (shown in  FIG. 3 ) so that microcomputer  140  may select the appropriate agitation speed value for the selected load size setting. Mechanical cleansing action during agitation portions of the wash cycle is therefore substantially optimized. 
   While four soil level settings and five load settings are set forth above in exemplary tables 1 and 2, it is anticipated that Tables 1 and 2 may include greater or fewer than four and five settings, respectively, without departing from the scope of the present invention. Further it is contemplated that additional soil level versus agitation time and load size settings versus agitation speed tables be included in controller memory  142  to provide agitation time and speed values for a variety of wash cycle types and profiles suited for particular garments or fabrics. Thus, agitation time and speed values may be customized across a wide variety of wash cycles and options that a user may select. 
   Once the agitation time duration value is set  180  and the agitation speed value is also set  188 , controller  138  executes  190  the agitation phase of the wash cycle when appropriate according to a main control program. When the agitation phase is complete, algorithm  170  ends  192 . 
   It is believed that those in the art of electronic controllers could construct and program controller  150  to implement the above-described methodology without further discussion. 
   A clothes washer control apparatus and method is therefore provided to substantially eliminate excessive wash cycle agitation. Consequently, laundry may be washed with less wear due to machine operations, and energy consumption in agitate portions is reduced. By controlling agitation portions of the wash cycle in response to the most pertinent input variables to the agitation process, both chemical and mechanical washing action are improved in an efficient and effective wash cycle. 
   While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.