Dryer appliance with thermal condition detection

Abstract

A dryer appliance operable to detect an extreme thermal event therein and related methods of detecting an extreme thermal event are provided. The dryer appliance includes a cabinet, a drum rotatably mounted within the cabinet, a heating system upstream of the drum, and an outlet duct downstream of the drum. The method includes and/or the dryer is configured for monitoring an outlet temperature, determining a temperature gradient of the monitored outlet temperature, and detecting the extreme thermal event based on the determined temperature gradient.

What is claimed is: 
     
         1 . A method of detecting an extreme thermal event in a dryer appliance, the dryer appliance comprising a cabinet, a drum rotatably mounted within the cabinet, a heating system upstream of the drum, and an outlet duct downstream of the drum, the method comprising:
 monitoring a temperature at the outlet duct of the dryer appliance;   determining a temperature gradient of the monitored temperature at the outlet duct of the dryer appliance;   detecting the extreme thermal event based on the determined temperature gradient; and   completely shutting down the dryer appliance after detecting the extreme thermal event.   
     
     
         2 . The method of  claim 1 , wherein determining the temperature gradient comprises calculating the difference between a current temperature at the outlet duct of the dryer appliance and a previous temperature at the outlet duct of the dryer appliance. 
     
     
         3 . The method of  claim 2 , wherein the previous temperature at the outlet duct of the dryer appliance is chronologically separated from the current temperature by a predetermined time period. 
     
     
         4 . The method of  claim 3 , wherein the predetermined time period is N seconds, and wherein N is a whole number. 
     
     
         5 . The method of  claim 3 , wherein the predetermined time period is between about three seconds and about ten seconds. 
     
     
         6 . The method of  claim 1 , wherein detecting the extreme thermal event based on the determined temperature gradient comprises comparing a current value of the temperature gradient to a threshold and detecting the extreme thermal event based on the current value of the determined temperature gradient exceeding the threshold. 
     
     
         7 . The method of  claim 1 , wherein detecting the extreme thermal event based on the determined temperature gradient comprises comparing a moving summation of the temperature gradient to a threshold and detecting the extreme thermal event based on the moving summation of the determined temperature gradient exceeding the threshold. 
     
     
         8 . The method of  claim 1 , wherein detecting the extreme thermal event based on the determined temperature gradient comprises determining a total cumulative length of time the temperature gradient has exceeded a threshold and detecting the extreme thermal event based on the total cumulative length of time the temperature gradient has exceeded the threshold being greater than a cumulative time threshold. 
     
     
         9 . The method of  claim 1 , wherein monitoring the temperature at the outlet duct of the dryer appliance comprises continuously measuring an air temperature in the outlet duct of the dryer appliance with a thermistor in the outlet duct. 
     
     
         10 . A dryer appliance operable to detect an extreme thermal event therein, the dryer appliance comprising:
 a cabinet;   a drum rotatably mounted within the cabinet, the drum defining a chamber for the receipt of articles for drying;   a heating system fluidly coupled to the drum whereby heated air flows from the heating system to the chamber of the drum for drying of articles therein;   an outlet duct fluidly coupled to the drum downstream of the chamber; and   a controller, the controller configured to:
 monitor a temperature at the outlet duct; 
 determine a temperature gradient of the monitored temperature at the outlet duct; 
 detect the extreme thermal event based on the determined temperature gradient; and 
 completely shut down the dryer appliance after detecting the extreme thermal event. 
   
     
     
         11 . The dryer appliance of  claim 10 , wherein the controller is configured to determine the temperature gradient by calculating the difference between a current temperature at the outlet duct of the dryer appliance and a previous temperature at the outlet duct of the dryer appliance. 
     
     
         12 . The dryer appliance of  claim 11 , wherein the previous temperature at the outlet duct of the dryer appliance is chronologically separated from the current temperature by a predetermined time period, the predetermined time period stored in a memory of the controller. 
     
     
         13 . The dryer appliance of  claim 12 , wherein the predetermined time period stored in the memory of the controller is N seconds, and wherein N is a whole number. 
     
     
         14 . The dryer appliance of  claim 12 , wherein the predetermined time period stored in the memory of the controller is between about three seconds and about ten seconds. 
     
     
         15 . The dryer appliance of  claim 10 , wherein the controller is configured to detect the extreme thermal event based on the determined temperature gradient by comparing a current value of the temperature gradient to a threshold and detecting the extreme thermal event based on the current value of the determined temperature gradient exceeding the threshold. 
     
     
         16 . The dryer appliance of  claim 10 , wherein the controller is configured to detect the extreme thermal event based on the determined temperature gradient by comparing a moving summation of the temperature gradient to a threshold and detecting the extreme thermal event based on the moving summation of the determined temperature gradient exceeding the threshold. 
     
     
         17 . The dryer appliance of  claim 10 , wherein the controller is configured to detect the extreme thermal event based on the determined temperature gradient by determining a length of time the temperature gradient has exceeded a threshold and detecting the extreme thermal event based on the length of time the temperature gradient has exceeded the threshold being greater than a time limit. 
     
     
         18 . The dryer appliance of  claim 10 , wherein the controller is configured to monitor the temperature at the outlet duct of the dryer appliance by continuously measuring an air temperature in the outlet duct of the dryer appliance with a thermistor in the outlet duct.