Method and apparatus for determining an imbalance condition in an appliance

Abstract

In one embodiment of the invention, an appliance and method is provided that can determine load imbalance or out-of-balance conditions. The appliances that typically apply load imbalance detection are clothes washers. A method of imbalance detection includes identifying parameter values that fluctuate with load imbalance over a predetermined sample period and determining a target parameter value from the identified parameter values. The method further includes calculating a parameter spread of the parameter values by comparing parameter values to the target parameter value. The method further includes converting the parameter spread into a weight value that reflects an imbalance condition.

1 . A method for determining an imbalance condition in an appliance, comprising:
 identifying parameter values that fluctuate with load imbalance over a predetermined sample period;   determining a target parameter value from the identified parameter values;   calculating a parameter value spread of the parameter values by comparing parameter values to the target parameter value;   converting said parameter spread into a weight value that reflects an imbalance condition.   
   
   
       2 . The method of  claim 1  wherein the predetermined sample period comprises a moving sample period. 
   
   
       3 . The method of  claim 1  wherein the target parameter value comprises an average. 
   
   
       4 . The method of  claim 1 , further comprising periodically recalculating the target parameter value and identifying additional parameter values. 
   
   
       5 . The method of  claim 1  wherein calculating said parameter value spread comprises:
 calculating an average parameter value from said parameter values; and   comparing said average parameter value to each said parameter value to arrive at an average deviation value;   
   
   
       6 . The method of  claim 1  wherein converting said parameter spread into a weight value comprises:
 dividing said parameter spread by a load constant value.   
   
   
       7 . The method of  claim 6 , wherein said parameter spread is multiplied by current motor speed. 
   
   
       8 . The method of  claim 1 , wherein the said parameter value comprises speed. 
   
   
       9 . The method of  claim 1 , wherein the said parameter value comprises voltage amplitude required to maintain a constant speed. 
   
   
       10 . The method of  claim 1 , wherein said appliance is an automatic washing machine. 
   
   
       11 . The method of  claim 1 , wherein said washing machine is a horizontal axis washer. 
   
   
       12 . The method of  claim 1 , wherein said washing machine is a vertical axis washer. 
   
   
       13 . A computer program embodied on a computer-readable medium, comprising:
 identifying parameter values that fluctuate with load imbalance over a predetermined sample period;   determining a target parameter value from the identified parameter values;   calculating a parameter value spread of the parameter values by comparing parameter values to the target parameter value;   converting said parameter spread into a weight value that reflects an imbalance condition.   
   
   
       14 . An appliance comprising:
 a vessel mounted for rotation about an axis;   a motor for rotating the vessel about an axis;   a processor configured to determine load imbalance; and   a memory for receiving and storing parameter data and instructions for determining load imbalance;   wherein the load imbalance is determined by:   identifying parameter values that fluctuate with load imbalance over a predetermined sample period;   determining a target parameter value from the identified parameter values;   calculating a parameter value spread of the parameter values by comparing parameter values to the target parameter value;   converting said parameter spread into a weight value that reflects an imbalance condition.   
   
   
       15 . The device of  claim 14  wherein the predetermined sample period comprises a moving sample period. 
   
   
       16 . The device of  claim 14  wherein the target parameter value comprises an average. 
   
   
       17 . The device of  claim 14 , wherein the load imbalance is further determined by periodically recalculating the target parameter value and identifying additional parameter values. 
   
   
       18 . The device of  claim 14  wherein calculating said parameter value spread comprises:
 calculating an average parameter value from said parameter values; and   comparing said average parameter value to each said parameter value to arrive at an average deviation value;   
   
   
       19 . The device of  claim 14  wherein converting said parameter spread into a weight value comprises:
 dividing said parameter spread by a load constant value based on the weight of the load in a washer.   
   
   
       20 . The device of  claim 14 , wherein said parameter spread is multiplied by current motor speed. 
   
   
       21 . The device of  claim 14 , wherein the said parameter value comprises speed. 
   
   
       22 . The device of  claim 14 , wherein the said parameter value comprises voltage amplitude required to maintain a constant speed. 
   
   
       23 . The device of  claim 14 , wherein said appliance is a washing machine. 
   
   
       24 . The device of  claim 23 , wherein said appliance is a horizontal axis washer. 
   
   
       25 . The device of  claim 23 , wherein said appliance is a vertical axis washer.