Method to detect an empty load in a clothes dryer

#Clothes dryers may have means to detect an empty load and end a drying cycle based upon such detection. Such detection may be conducted with the use of various sensors, such as humidity sensors and temperature sensors. By making a quick detection, energy consumption in the clothes dryer could be reduced. Additionally, a quick detection of an empty load condition may allow the dryer to be available to run a useful cycle of operation rather than operating on an empty load. On the other hand, a false detection of an empty load may result in incomplete drying of clothes.

#One embodiment of the invention is related to a method for determining an empty load in a clothes dryer having a drying chamber with an air inlet and an air outlet, and operable according to a predetermined cycle of operation. Air may be supplied through the drying chamber by introducing air into the air inlet and exhausting air from the air outlet. The air may be selectively heated such that the outlet temperature of the air repeatedly cycles between an upper temperature limit and a lower temperature limit threshold and repeatedly determining a local minimum temperature of the inlet air. An inlet temperature difference of the local minimums may be repeatedly determined and used to determine that the drying chamber is empty when the inlet temperature difference satisfies a predetermined threshold.

#In the drawings:

#FIG. 1 is a perspective view of a clothes dryer.

#FIG. 2 is a schematic sectional view through the clothes dryer of FIG. 1 showing a drying chamber with an air inlet and an air outlet.

#The present invention relates generally to a clothes dryer and detecting an empty load condition. More specifically, the invention is related to detecting an empty load condition by controlling the clothes dryer outlet air temperature and monitoring the corresponding inlet air temperature.

#FIG. 1 is a schematic view of a clothes dryer 10 with a cabinet formed by panels mounted to a chassis. There is a rear panel 20, side panel 22, top panel 24, and front panel 26. There may be an opening within the front panel 26 that a door 32 selectively opens/closes. The door 32 may be opened to access a drying chamber 34, which is illustrated being formed by a drum 28, located within the interior of the cabinet. The drum 28 may be rotatable and may be rotated by a drive belt 52 connected to a motor 54 (FIG. 2). A user interface 36 may be disposed on the front housing panel 26 of the clothes dryer 10. The user interface 36 may provide for a user to select or modify a predetermined cycle of operation of the clothes dryer.

#While the invention is described in the context of a clothes dryer, it is applicable to other types of laundry treating devices where drying occurs. For example, “combo” machines, which perform both a clothes washing and a clothes drying function may incorporate the invention.