Dryer appliance and method for dryer cycle control

Abstract

A dryer appliance, a controller, and a method for dryer cycle control include positioning a heater control thermostat in thermal communication with air in fluid communication with a laundry chamber. The heater control thermostat includes a thermostat having a heater control set point relative to which a heater assembly operates to provide heated air. An outlet sensor is positioned in communication with air at an outlet portion of duct. The outlet sensor includes a sensing temperature set point or a conductivity threshold. The heater control thermostat is operably coupled to the heater assembly to selectively output heat based on the heater control set point and a pre-determined heating period. The outlet sensor is coupled to the heater assembly to operate the heater assembly until the sensing temperature set point or conductivity threshold is met after operating the heater assembly for the heating period based on the heater control set point.

What is claimed is: 
     
         1 . A dryer appliance, the dryer appliance comprising:
 a heater assembly configured to generate heated air through a duct, wherein the duct is in fluid communication with a chamber formed at a drum for receiving laundry articles for drying, wherein an inlet portion of the duct extends from the heater assembly to the chamber to provide heated air to the chamber, and wherein an outlet portion of the duct extends from the chamber to receive air from the chamber;   a heater control thermostat positioned in thermal communication with air at the duct, the heater control thermostat comprising a first bi-metal thermostat comprising a heater control set point relative to which the heater assembly operates to provide heated air to the chamber;   an outlet sensor positioned in communication with air at the outlet portion of duct, the outlet sensor comprising a second bi-metal thermostat comprising a sensing temperature set point or a conductivity sensor comprising a conductivity threshold;   a controller comprising a control circuit comprising a heater control circuit and a plurality of control stages in serial operational arrangement, the plurality of control stages comprising a timer stage and a sensing stage,   wherein the heater control circuit operably couples the heater control thermostat to the heater assembly to selectively output heat based on the heater control set point at the heater control thermostat,   wherein the timer stage is configured to operate the heater assembly for a pre-determined heating period and based on the heater control set point at the heater control thermostat,   wherein the control circuit is configured to commence the sensing stage after the heating period,   wherein the sensing stage is configured to operate the heater assembly until the sensing temperature set point or the conductivity threshold at the outlet sensor is met by air at the duct, and wherein the control circuit is configured to disable heat generation at the heater assembly after the sensing temperature set point or conductivity threshold is met.   
     
     
         2 . The dryer appliance of  claim 1 , wherein the heater control thermostat is positioned at the inlet portion of the duct. 
     
     
         3 . The dryer appliance of  claim 1 , wherein the outlet sensor is positioned at the outlet portion of the duct. 
     
     
         4 . The dryer appliance of  claim 1 , wherein the controller is an analog controller. 
     
     
         5 . The dryer appliance of  claim 1 , wherein the control circuit is configured to commence the sensing stage after two or more timer stages comprising respective heater periods. 
     
     
         6 . The dryer appliance of  claim 5 , wherein the timer stages comprise respective heater control thermostats and having respective heater control set points different from one another. 
     
     
         7 . A method for cycle control at a dryer appliance, the method comprising:
 positioning a heater control thermostat in thermal communication with air at an inlet portion of a duct in fluid communication with a chamber for receiving laundry articles for drying, wherein the heater control thermostat comprises a first bi-metal thermostat comprising a heater control set point relative to which a heater assembly operates to provide heated air to the chamber;   positioning an outlet sensor in communication with air at an outlet portion of duct, wherein the outlet sensor comprises a second bi-metal thermostat comprising a sensing temperature set point or a conductivity sensor comprising a conductivity threshold;   operably coupling the heater control thermostat to the heater assembly to selectively output heat based on the heater control set point and a pre-determined heating period; and   operably coupling the outlet sensor to the heater assembly to operate the heater assembly until the sensing temperature set point or conductivity threshold is met after operating the heater assembly for the heating period based on the heater control set point, wherein the outlet sensor disables heat generation at the heater assembly after the sensing temperature set point is met.   
     
     
         8 . The method of  claim 7 , wherein the cycle control is an analog cycle control. 
     
     
         9 . The method of  claim 7 , the method comprising operably coupling a plurality of heater control thermostats to the heater assembly, wherein the plurality of heater control thermostats comprise respective heater control set points and respective heating periods. 
     
     
         10 . The method of  claim 9 , the method comprising operably coupling the outlet sensor to the heater assembly to operate the heater assembly after operating the heater assembly for the respective heating periods of the plurality of heater control thermostats. 
     
     
         11 . The method of  claim 10 , wherein the respective heater control set points and respective heating periods of the plurality of heater control thermostats are different from respective ones of another. 
     
     
         12 . The method of  claim 9 , the method comprising operably coupling a plurality of outlet sensors to the heater assembly, wherein the plurality of outlet sensors comprise respective sensing temperature set points. 
     
     
         13 . The method of  claim 12 , wherein the respective sensing temperature set points of the plurality of outlet sensors are different set points from one another. 
     
     
         14 . A controller for a dryer appliance, the controller comprising:
 a control circuit comprising a first heater control circuit and a plurality of control stages, the plurality of control stages comprising a timer stage and a sensing stage,   wherein the first heater control circuit is operably coupled to a heater control thermostat configured to control heat output from a heater assembly based on a heater control set point,   wherein the timer stage is configured to operate the heater control circuit for a pre-determined heating period and based on the heater control set point,   wherein the control circuit is configured to commence the sensing stage after the heating period,   wherein the control circuit comprises a second heater control circuit operably coupled to an outlet sensor comprising a sensing temperature set point or a conductivity threshold, wherein the sensing stage is configured to disable the second heater control circuit after the sensing temperature set point or conductivity threshold is met.   
     
     
         15 . The controller of  claim 14 , wherein the heater control thermostat comprises a first bi-metal thermostat comprising the heater control set point relative to which a heater assembly operates to generate heated air. 
     
     
         16 . The controller of  claim 15 , wherein the outlet sensor comprises a second bi-metal thermostat comprising the sensing temperature set point at which heat generation at the heater assembly is disabled. 
     
     
         17 . The controller of  claim 14 , wherein the plurality of control stages comprises one or more sensing stages and two or more timer stages. 
     
     
         18 . The controller of  claim 17 , wherein the plurality of control stages comprises a temperature set point and an active heater period respective to each timer stage. 
     
     
         19 . The controller of  claim 14 , wherein the controller is an analog controller. 
     
     
         20 . The controller of  claim 14 , wherein the control circuit is configured to commence the sensing stage after two or more timer stages comprising respective heater periods.