Fluid entrapment detection

Abstract

A washing machine includes a cabinet, a wash tub supported within the cabinet, a spin basket for holding a wash load, the spin basket rotatable in the wash tub by a motor, and a controller for driving the motor to rotate the spin basket. The controller is adapted to detect water entrapment within a wash load in a spin basket of a washing machine by measuring a first parameter indicative of the rotational inertia of the spin basket when accelerated to a first spin speed, controlling the spin basket to dewater a wash load in the spin basket, measuring a second parameter indicative of the rotational inertia of the spin basket at the first speed, comparing the first and second parameters, and detecting whether there is water entrapped in the wash load based on the comparison between the first and second parameters.

1 . A washing machine comprising:
 a cabinet,   a wash tub supported within the cabinet;   a spin basket for holding a wash load, the spin basket rotatable in the wash tub by a motor,   a controller for driving the motor to rotate the spin basket, the controller adapted to detect water entrapment within a wash load in a spin basket of a washing machine by:   measuring a first parameter indicative of the rotational inertia of the spin basket when accelerated to a first spin speed,   controlling the spin basket to dewater a wash load in the spin basket,   measuring a second parameter indicative of the rotational inertia of the spin basket at the first speed,   comparing the first and second parameters, and   detecting whether there is water entrapped in the wash load based on the comparison between the first and second parameters.   
   
   
       2 . A washing machine according to  claim 1  wherein if the controller detects that there is water entrapped in the wash load, the controller operates the motor to rotate the spin basket a second spin speed, and wherein the controller detects that there is no water entrapped in the wash load, the controller operates the motor to rotate the spin basket at a third spin speed, the third spin speed being greater than the second spin speed. 
   
   
       3 . A washing machine according to  claim 1  wherein it is detected that there is water entrapped if the rotational inertia indicated by the second parameter is greater than the rotational inertia indicated by the first parameter. 
   
   
       4 . A washing machine according to  claim 1  wherein measuring the first parameter comprises:
 a) the controller operating the motor to apply a torque to the spin basket to rotate spin basket at the first spin speed,   b) the controller operating the motor to remove the torque and allow the spin basket to decelerate to an idle spin speed, and   c) the controller measuring a first time for the spin basket to decelerate to the idle speed,   wherein the measured first time is the first parameter.   
   
   
       5 . A washing machine according to  claim 4  wherein the step of measuring the second parameter comprises:
 a) the controller operating the motor to apply a torque to the spin basket to rotate spill basket at the first spin speed,   b) the controller operating the motor to remove the torque and allow the spin basket to decelerate to a idle spin speed, and   c) the controller measuring a second time for the spin basket to decelerate to the idle speed,   wherein the measured second time is the second parameter,   
   
   
       6 . A washing machine according to  claim 5  wherein it is detected that there is water entrapped if the second time is larger than the first time. 
   
   
       7 . A washing machine according to  claim 1  wherein the step of measuring the first parameter comprises:
 a) the controller operating the motor to apply a torque to the spin basket to rotate spin basket at the first spin speed,   b) the controller operating the motor to remove the torque and allow the spin basket to decelerate to a idle spin speed,   c) the controller measuring a time for the spin basket to decelerate to the idle speed,   d) the controller repeating steps a)-c) at least once to obtain one or more additional measured times, and   e) the controller calculating the average of the measured times,   wherein the average of the measure times is the first parameter.   
   
   
       8 . A washing machine according to  claim 7  wherein the step of measuring the second parameter comprises:
 a) the controller operating the motor to apply a torque to the spin basket to rotate spin basket at the first spin speed,   b) the controller operating the motor to remove the torque and allow the spin basket to decelerate to a idle spin speed,   c) the controller measuring a time for the spin basket to decelerate to the idle speed,   d) the controller repeating steps a)-c) at least once to obtain one or more additional measured times, and   e) the controller calculating the average of the measured times,   wherein the average of the measure times is the first parameter.   
   
   
       9 . A washing machine according to  claim 1  wherein the first parameter indicative of the rotational inertia of the spin basket when accelerated to a first spin speed is the time taken for the spin basket to decelerate from the first speed to an idle speed. 
   
   
       10 . A washing machine according to  claim 1  wherein the second parameter indicative of the rotational inertia of the spin basket when accelerated to a first spin speed is the time taken for the spin basket to decelerate from the first speed to an idle speed. 
   
   
       11 . A washing machine according to  claim 2  wherein the second spin speed is less 670 rpm. 
   
   
       12 . A washing machine according to  claim 2  wherein the third spin speed is greater than 670 rpm. 
   
   
       13 . A washing machine according to  claim 1  wherein the first speed is between 15 rpm and 150 rpm. 
   
   
       14 . A washing machine according to any one of  claims 4 ,  5 ,  7  or  8  wherein the idle speed is between 35 rpm and 0 rpm. 
   
   
       15 . A method of detecting water entrapment within a wash load in a spin basket of a washing machine, comprising the steps of:
 measuring a first parameter indicative of the rotational inertia of the spin basket when accelerated to a first spin speed,   dewatering the wash load,   measuring a second parameter indicative of the rotational inertia of the spin basket at the first speed,   comparing the first and second parameters, and   determining whether there is water entrapped in the wash load based on the comparison between the first and second parameters.   
   
   
       16 . A method according to  claim 15  wherein if it is determined that there is water entrapped in the wash load, rotating the spin basket a second spin speed, and wherein if it is determined that there is no water entrapped in the wash load, rotating the spin basket at a third spin speed, the third spin speed being greater than the second spin speed. 
   
   
       17 . A method according to  claim 15  wherein it is determined that there is water entrapped if the rotational inertia indicated by the second parameter is greater than the rotational inertia indicated by the first parameter. 
   
   
       18 . A method according to  claim 15  wherein the step of measuring the first parameter comprises:
 a) applying a torque to the spin basket to rotate spin basket at the first spin speed,   b) removing the torque and allowing the spin basket to decelerate to a idle spin speed, and   c) measuring a first time for the spin basket to decelerate to the idle speed,   wherein the measured first time is the first parameter.   
   
   
       19 . A method according to  claim 18  wherein the step of measuring the second parameter comprises:
 a) applying a torque to the spin basket to rotate spin basket at the first spin speed,   b) removing the torque and allowing the spin basket to decelerate to a idle spin speed, and   c) measuring a second time for the spin basket to decelerate to the idle speed,   wherein the measured second time is the second parameter,   
   
   
       20 . A method according to  claim 19  wherein it is determined that there is water entrapped if the second time is larger than the first time. 
   
   
       21 . A method according to  claim 15  wherein the step of measuring the first parameter comprises:
 a) applying a torque to the spin basket to rotate spin basket at the first spin speed,   b) removing the torque and allowing the spin basket to decelerate to a idle spin speed,   c) measuring a time for the spin basket to decelerate to the idle speed,   d) repeating steps a)-c) at least once to obtain one or more additional measured times, and   e) calculating the average of the measured times,   wherein the average of the measure times is the first parameter.   
   
   
       22 . A method according to  claim 21  wherein the step of measuring the second parameter comprises:
 a) applying a torque to the spin basket to rotate spin basket at the first spin speed,   b) removing the torque and allowing the spin basket to decelerate to a idle spin speed,   c) measuring a time for the spin basket to decelerate to the idle speed,   d) repeating steps a)-c) at least once to obtain one or more additional measured times, and   e) calculating the average of the measured times,   wherein the average of the measure times is the second parameter.   
   
   
       23 . A method according to  claim 15  wherein the first parameter indicative of the rotational inertia of the spin basket when accelerated to a first spin speed is the time taken for the spin basket to decelerate from the first speed to an idle speed. 
   
   
       24 . A method according to  claim 15  wherein the second parameter indicative of the rotational inertia of the spin basket when accelerated to a first spin speed is the time taken for the spin basket to decelerate from the first speed to an idle speed. 
   
   
       25 . A method according to  claim 16  wherein the second spin speed is less 670 rpm. 
   
   
       26 . A method according to  claim 16  wherein the third spin speed is greater than 670 rpm. 
   
   
       27 . A method according to  claim 15  wherein the first speed is between 15 rpm and 150 rpm. 
   
   
       28 . A method according to any one of  claims 18 ,  19 ,  21  or  22  wherein the idle speed is between 35 rpm and 0 rpm. 
   
   
       29 . A method according to any one of  claims 18 ,  19 ,  21  or  22  wherein measuring a first or second time for the spin basket to decelerate to an idle spin speed comprises:
 measuring the time taken for the spin basket to decelerate from an intermediate spill speed between the first and idle spin speed to the idle spin speed.   
   
   
       30 . A washing machine according to any one of  claims 4 ,  5 ,  7  or  8  wherein measuring a first or second time for the spin basket to decelerate to an idle spin speed comprises:
 measuring the time taken for the spin basket to decelerate from an intermediate spin speed between the first and idle spin speed to the idle spin speed.   
   
   
       31 . A washing machine comprising:
 a cabinet,   a wash tub supported within the cabinet;   a spin basket for holding a wash load, the spin basket rotatable in the wash tub by a motor,   a controller for driving the motor to rotate the spin basket, the controller adapted to detect water entrapment within a spin basket of a washing machine by:   measuring a first parameter indicative of the rotational inertia of the spin basket when accelerated to a first spin speed,   controlling the spin basket to dewater a wash load in the spin basket,   measuring a second parameter indicative of the rotational inertia of the spin basket at the first speed,   comparing the first and second parameters, and   detecting whether there is water entrapped in the wash load based on the comparison between the first and second parameters.