Method for determining load size in a clothes dryer using an infrared sensor

1. A method for controlling the operation of a clothes dryer having a rotatable drum defining a drying chamber and an infrared temperature sensor directed toward the drying chamber, the method comprising:

rotating the drum with a load of laundry in the drying chamber;

taking a plurality of temperature readings over time of the load of laundry with the infrared sensor while the drum is rotating;

determining a temperature variation in the plurality of temperature readings; and

determining a load size estimation based on at least one of the temperature variation and a delay time wherein the delay time is a time it takes for the temperature variation to satisfy a predetermined threshold.

2. The method of claim 1 wherein the rotating of the drum comprises rotating the drum at a rotational speed to tumble the load of laundry within the drying chamber.

3. The method of claim 1 wherein the taking a plurality of temperature readings comprises taking temperature readings at a predetermined sampling rate to form a plurality of consecutive temperature values.

4. The method of claim 3 wherein the determining of the temperature variation comprises determining the difference between the plurality of consecutive temperature values.

5. The method of claim 4 wherein the determining of the difference between the plurality of consecutive temperature values comprises sequentially determining the difference between the plurality of consecutive temperature values.

6. The method of claim 1 wherein the determining of the delay time comprises determining a time it takes for the temperature variation to exceed the predetermined threshold in response to the spraying of a fluid on the laundry load.

7. The method of claim 6 wherein the determining of the delay time comprises determining the time between the initiation of the spraying and the exceeding of the predetermined threshold.

8. The method of claim 1 , further comprising adjusting a cycle of operation of the clothes dryer in response to the load size estimation.

9. The method of claim 8 wherein the adjusting the cycle of operation comprises setting an operating parameter for the cycle of operation.

10. The method of claim 9 wherein the at least one of the operating parameters comprises at least one of: a rotational speed of the drum, a direction of rotation of the drum, a temperature in the drying chamber, an air flow through the drying chamber, an energy profile for the cycle of operation, a cycle time, a cycle phase time, an operation of the infrared temperature sensor, an algorithm used by the clothes dryer, a type of treating chemistry, an amount of treating chemistry, a start or end of cycle condition, and a start or end cycle step condition.

11. The method of claim 1 , further comprising supplying heated air to the drying chamber.

12. The method of claim 11 wherein the supplying of the heated air is provided for a time sufficient for the load of laundry to reach a uniform temperature.

13. The method of claim 12 wherein the supplying of the heated air occurs prior to the taking of the temperature readings.

14. The method of claim 12 wherein the determining of the load size estimation is based on both the temperature variation and the delay time.

15. The method of claim 14 wherein when the predetermined threshold is satisfied by a delay time greater than the predetermined threshold, it indicates a large load.

16. The method of claim 14 wherein when the predetermined threshold is satisfied by a delay time greater than the predetermined threshold, it indicates a load of about 9 pounds and greater.

17. The method of claim 1 wherein the determining the temperature variation comprises determining the maximum temperature variation.

18. The method of claim 17 wherein the determining the maximum temperature variation comprises determining the maximum temperature variation from consecutive temperature readings for a predetermined time.

19. The method of claim 18 wherein the determining of the load size estimation is conducted as part of a drying cycle of operation and the predetermined time is less than the duration of the drying cycle of operation.

20. The method of claim 17 wherein load size estimation comprises determining whether the maximum temperature variation satisfies a predetermined maximum temperature variation threshold.

21. The method of claim 20 wherein the predetermined maximum temperature variation threshold is indicative of a small load.

22. The method of claim 20 wherein the predetermined maximum temperature variation threshold is indicative of a load of about 1.5 pounds and less.

23. The method of claim 1 wherein the determining the temperature variation comprises determining the difference between a first of the plurality of temperature readings at a first time and a second of the plurality of temperature readings at a second time, later than the first time, to define a temperature change.

24. The method of claim 23 wherein the plurality of temperature readings comprises taking temperature readings at a predetermined sampling rate to form the plurality of temperature readings, and the first and the second of the plurality of temperature readings are not consecutive temperature readings.

25. The method of claim 23 wherein load size estimation comprises determining whether the temperature change satisfies a predetermined temperature change threshold.

26. The method of claim 25 wherein the satisfying of the predetermined temperature change threshold is indicative of a small load.

27. The method of claim 25 wherein the satisfying of the predetermined temperature change threshold is indicative of a load of about 1.5 pounds and less.

28. The method of claim 25 wherein the load size estimation further comprises determining the delay time.

29. The method of claim 28 wherein when the predetermined temperature change threshold is satisfied by a temperature change greater than zero and the predetermined delay time threshold is satisfied, it indicates a medium load.

30. The method of claim 28 wherein when the predetermined temperature change threshold is satisfied by a temperature change greater than zero and the predetermined delay time threshold is satisfied, it indicates a load of about 3 to 8 pounds.

31. A cycle of operation of a clothes dryer have a rotatable drum defining a drying chamber and an infrared temperature sensor directed toward the drying chamber, the cycle of operation comprising:

rotating the drum with a load of laundry in the drying chamber;

supplying heated air to the drying chamber;

conducting a first spraying of fluid into the drum to wet the load of laundry;

taking a plurality of temperature readings of the load of laundry with the infrared sensor while the drum is rotating and after the initiation of the conducting of the first spraying;

determining a temperature variation in the plurality of temperature readings over time;

determining a delay time, wherein the delay time is a time it takes for the temperature variation to satisfy a predetermined threshold in response to the first spraying of fluid;

determining a load size estimation based on at least one of the temperature variation and the delay time; and

setting an operating parameter of the cycle of operation in response to the load size estimation.

32. The cycle of operation according to claim 31 , further comprising conducting a second spraying of fluid into the drum based on the load size estimation.

33. The cycle of operation according to claim 32 wherein the supplying of heated air is conducted after the conducting of the second spraying of fluid to dry the load of laundry.

34. The cycle of operation according to claim 31 wherein the supplying of heated air is conducted for a sufficient time for the load of laundry to reach a uniform temperature prior to the conducting of the first spraying of fluid.