Adaptive drain algorithm for clothes washers

Abstract

This disclosure is related to a system and method which minimizes the period of time in which a drain pump is running in a washing machine unit. The method includes determining the amount of washer fluid used to fill a washing machine tub when the washing machine has entered the draining portion of the cycle, measuring the time it takes in order to trip a water level sensor. The method generally continues with calculating a predicted time to drain and operating a drain pump according to the predicted time to drain. Use of this method minimizes the opportunities for machine malfunctions while further minimizing the opportunity for the pump to run dry, creating noise and increasing the length of the entire washing cycle.

1 . A method for minimizing the period of time in which a drain pump is running in a vertical load washing machine comprising:
 determining an amount of fluid to fill a washing machine tub;   measuring a time between a first level and a second level in said washing machine tub during draining;   calculating a predicted time to drain based at least in part on said time and said amount to fill; and   operating a drain pump for a period of time related to said predicted time to drain.   
   
   
       2 . The method according to  claim 1 , further comprising:
 deriving a minimum drain time; and   operating said drain pump for at least said minimum drain time.   
   
   
       3 . The method according to  claim 1 , further comprising:
 setting minimal threshold for said predicted time to drain; and   if predicted time to drain does not meet said threshold, operating said drain pump for said predicted time to drain and operating said drain pipe a second time for at least a portion of time until said threshold is meet.   
   
   
       4 . The method according to  claim 1 , wherein at said first level there is a first pressure switch and at said second level there is a second pressure switch. 
   
   
       5 . The method according to  claim 4 , further comprising checking for defects in said first and second pressure switches. 
   
   
       6 . The method according to  claim 4 , wherein said first pressure switch is configured to act as a safety switch in order to prevent flooding. 
   
   
       7 . The method according to  claim 1 , wherein determining said amount of fluid to fill said washing machine tub includes using a constant flow rate valve. 
   
   
       8 . The method according to  claim 1 , wherein the determining said amount of fluid to fill said washing machine tub included using a flow meter. 
   
   
       9 . The method according to  claim 1 , further comprising proceeding to the next cycle after said period of time has passed. 
   
   
       10 . The method according to  claim 1 , wherein calculating said predicted time is according to the formula
   A+B(TTT)−C(GTF)   where A, B and C are constants and TTT is the time to trip and GTF is said measure of fluid.   
   
   
       11 . A method of operating a drain pump in order to minimize the length of time a drain pump is running to drain a washer tub comprising:
 determining a measure of fluid to fill said washer tub;   initiating a timer;   initiating a drain pump;   recording a time to trip where said time to trip is the time it takes from the start of said drain pump to when a lower switch trips; and   calculating a predicted time to drain based at least in part on said time to trip and said measure of fluid to fill said washer tub.   
   
   
       12 . The method according to  claim 11 , further comprising:
 turning off the drain pump if an upper level switch does not trip and said lower level switch does trip; and   registering a fault of the upper level switch.   
   
   
       13 . The method according to  claim 11 , further comprising if said lower level switch has not tripped when said timer reaches a predetermined amount of time turning off said drain pump; and
 registering a lower switch fault.   
   
   
       14 . A system for an adaptive drain that calculates a predicted time for a washing machine to drain out fluid comprising:
 a washer tub having an upper level switch and a lower level switch;   a drain pump configured to pump an amount of fluid out of said washer tub; and   a controller adapted to regulate said drain pump to drain said washer tub for a period of time calculated to reflect a relationship between the time between the initiation of said drain pump, the time for said upper level switch to trip, and the time for said lower level switch to trip and the amount of fluid that said tub is holding.   
   
   
       15 . The system according to  claim 14  wherein said upper level switch is a control switch that signals when said washer tub is in danger of overflowing. 
   
   
       16 . The system according to  claim 14  wherein said upper level switch and lower level switch are pressure switches. 
   
   
       17 . The system according to  claim 14  wherein said upper level switch and said lower level switch include fault detection. 
   
   
       18 . The system according to  claim 17  wherein said upper level switch and said lower level switch reset after a fault is cleared. 
   
   
       19 . The system according to  claim 14  wherein said controller is further configured to calculate said period of time to drain based on a predicted to drain according to the formula
   A+B(TTT)−C(GTF)   where A, B and C are constants and TTT is the time to trip and GTF is said measure of fluid.   
   
   
       20 . The system according to  claim 14  further comprising a constant flow rate value adapted to measure the amount of fluid used to fill said washer tub.