Method for maximizing drum rotational speed by continuously monitoring inertia during extraction

Abstract

A laundry treating appliance may have a rotatable drum defining a treating chamber for receiving a laundry load, a motor rotatably driving the drum, and a controller controlling the operation of the motor. The laundry treating appliance may be operated by accelerating the drum with the motor toward a final speed greater than a satellizing speed, determining a mass value indicative of the mass of the rotating drum and contents within the treating chamber during the accelerating, determining a current rotational speed during the acceleration, calculating a force value indicative of a force acting on the drum based on the determined mass value and the current rotational speed, comparing the force value to a reference force value, and repeating the determining, calculating, and comparing during the acceleration, and ceasing the accelerating when the force value obtains a predetermined relationship with the reference force value.

What is claimed is: 
     
         1 . A method of operating a laundry treating appliance having a rotatable drum defining a treating chamber for receiving a laundry load for treatment, a motor rotatably driving the drum, and a controller controlling the operation of the motor to effect the rotation of the drum, the method comprising:
 a) accelerating the drum with the motor to increase a rotational speed of the drum toward a final speed greater than a satellizing speed;   b) determining a mass value indicative of the mass of the rotating drum and laundry load within the drum during the accelerating;   c) determining a current rotational speed during the acceleration;   d) calculating a force value indicative of a force acting on the drum based on the determined mass value and the current rotational speed;   e) comparing the force value to a reference force value; and   f) repeating b-e during the accelerating, and terminating the accelerating when the force value satisfies a predefined relationship with the reference force value.   
     
     
         2 . The method of  claim 1  wherein the accelerating of the drum is continuous. 
     
     
         3 . The method of  claim 2  wherein the accelerating of the drum is constant. 
     
     
         4 . The method of  claim 2  wherein the accelerating of the drum defines a speed profile without any speed plateaus. 
     
     
         5 . The method of  claim 1  wherein the determining the mass value comprises determining an inertia of the rotating drum and laundry load within the drum. 
     
     
         6 . The method of  claim 5  wherein the determining the inertia comprises determining at least a combined inertia of the drum and the laundry load within the drum. 
     
     
         7 . The method of  claim 5  wherein the determining the inertia comprises determining a change in torque of the motor or power utilized by the motor. 
     
     
         8 . The method of  claim 1  wherein the calculating a force value indicative of a force acting on the drum comprises calculating at least one of a first force value indicative of a hoop stress on the drum and a second force value indicative of a bending moment acting on the drum shaft. 
     
     
         9 . The method of  claim 8  wherein the calculating a force value indicative of a force acting on the drum comprises calculating both the first and second force values. 
     
     
         10 . The method of  claim 9  wherein the comparing the force value comprises comparing both the first and second force values to corresponding first and second reference force values, and terminating the accelerating comprises terminating the accelerating when at least one of the first and second force values satisfies a predefined relationship with the corresponding first and second reference force values. 
     
     
         11 . The method of  claim 1  wherein the reference force value comprises a threshold force value and the predefined relationship comprises the force value satisfying the threshold force value. 
     
     
         12 . The method of  claim 11  wherein the satisfying the threshold force value comprises the force value exceeding the threshold force value. 
     
     
         13 . A method of operating a laundry treating appliance having a rotatable drum defining a treating chamber for receiving a laundry load for treatment, a motor rotatably driving the drum, and a controller controlling the operation of the motor to effect the rotation of the drum, the method comprising:
 setting a maximum rotational speed of the drum, which is greater than a satellizing speed, based on a maximum force condition of the drum that is a function of the mass of the drum and the rotational speed of the drum;   accelerating the drum, with the motor, to increase a rotational speed of the drum toward the maximum rotational speed;   repeatedly determining the mass and the rotational speed during the accelerating;   re-setting the maximum rotational speed based on the determined mass and rotational speed; and   terminating the accelerating when the determined rotational speed satisfies a predefined relationship with the maximum rotational speed.   
     
     
         14 . The method of  claim 13  wherein the accelerating of the drum is continuous. 
     
     
         15 . The method of  claim 14  wherein the accelerating of the drum is constant. 
     
     
         16 . The method of  claim 14  wherein the determining the mass comprises determining an inertia of the rotating drum and laundry load. 
     
     
         17 . The method of  claim 16  wherein the maximum force condition comprises at least one of a maximum hoop stress on the drum and a maximum bending moment acting on the drum shaft. 
     
     
         18 . A laundry treating appliance for treating a laundry load according to at least one cycle of operation, comprising:
 a rotatable drum defining a treating chamber for receiving a laundry load for treatment;   a motor operably coupled to and rotatably driving the drum;   a speed sensor providing a speed output indicative of the rotational speed of the drum;   a mass sensor providing a mass output indicative of the mass of the rotating drum; and   a controller receiving as input the speed output and the mass output, and controlling the motor to effect an accelerating of the drum toward a maximum rotational speed of the drum, which is calculated by the controller based on a maximum force condition of the drum that is a function of the mass of the drum and the rotational speed of the drum, while re-setting the maximum rotational speed during the accelerating based on the received speed output and mass output, and terminating the accelerating when the rotational speed satisfies a predefined relationship with the maximum rotational speed.   
     
     
         19 . The laundry treating appliance of  claim 18  wherein the maximum force condition comprises at least one of a maximum hoop stress on the drum and a maximum bending moment acting on the drum shaft. 
     
     
         20 . The laundry treating appliance of  claim 19  wherein the speed output and the mass output are both outputs related to the operation of the motor.