METHOD FOR DETERMINING THE LIQUID LEVEL IN A BOILER

• US 20100107886A1
• Filed: 03/21/2008
• Published: 05/06/2010
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Xiao, Taikang, Estrada, Jose Luis, Thirumazhisai Sankaralingam, Tamilselvan, Tiew, Hock Soon, Tay, Barry Eng Keong, Belle, Chaithra, Chadha, Jasmeet Singh
• Granted Patent: US 9,593,975 B2
• Time in Patent Office: Days
• US Class Current: 99/281
• CPC Class Codes: D06F 75/12 the steam being produced from water supplied to the iron from an external source
• CPC Class Codes: F22B 1/285 the water being fed by a pump to the reservoirs
• CPC Class Codes: F22B 37/78 Adaptations or mounting of level indicators level indicators per se G01F
• CPC Class Codes: G01F 23/22 by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water involving the use of floats G01F23/30
• CPC Class Codes: G01F 23/246 thermal devices

Abstract

The present invention relates to a method of determining a liquid level in a boiler (12) of an apparatus (10) having a temperature sensor (24) for sensing a temperature (T) which is indicative of a temperature of the liquid inside the boiler (12), comprising the steps of: inducing a temporary deflection of the temperature (T) sensed by the temperature sensor (24); determining an evaluation temperature (T_ev) sensed by the temperature sensor (24) after inducing the deflection; and determining the liquid level from at least the evaluation temperature (T_ev). Advantageously, the invention provides that the evaluation temperature (T_ev) is determined by monitoring the deflection and by defining an extreme value (T_max, T_min) of the deflection as the evaluation temperature (T_ev). Further, the present invention relates to an steam generating apparatus adapted for executing such a method, a domestic appliance having such a steam generating apparatus.

Claims

1. A method of determining a liquid level in a boiler (12) of an apparatus (10) having a temperature sensor (24) for sensing a temperature (T) which is indicative of a temperature of the liquid inside the boiler (12), comprising the steps of:

inducing a temporary deflection of the temperature (T) sensed by the temperature sensor (24);

determining an evaluation temperature (T_ev) sensed by the temperature sensor (24) after inducing the deflection; and

determining the liquid level from at least the evaluation temperature (T_ev), characterized in that

the evaluation temperature (T_ev) is determined by monitoring the deflection and by defining an extreme value (T_max, T_min) of the deflection as the evaluation temperature (T_ev).

2. The method according to claim 1, wherein the temporary deflection of the temperature (T) is induced by turning on a heating device (14) for heating the liquid.

3. The method according to claim 1, wherein the liquid level is determined as low, if the evaluation temperature (T_ev) is greater than or equal to a first low level threshold (T_low1).

4. The method according to claim 2, wherein the heating device (14) stays turned on until the temperature is greater than or equal to a first threshold temperature (T_th1).

5. The method according to claim 4, wherein the liquid level is determined as low, if the difference between the evaluation temperature (T_ev) and the first threshold temperature (T_th1) is greater than or equal to a second low level threshold (T_low2).

6. The method according to claim 1, wherein the temporary deflection of the temperature (T) is induced by filling liquid into the boiler (12).

7. The method according to claim 6, wherein the liquid level is determined based on a difference between a comparison temperature (T₁) and the evaluation temperature (T_ev), wherein the comparison temperature (T₁) is sensed when filling liquid into the boiler (12) is started.

8. The method according to claim 7, wherein the comparison temperature (T₁) is sensed after an accumulated time of extracting steam from the boiler (12) is greater than or equal to a steaming threshold.

9. The method according to claim 8, wherein the steaming threshold is varied depending on the liquid level as determined before.

10. The method according to claim 1, wherein it is concluded that a liquid tank (40) from which a pump (38) supplies the boiler (12) with liquid is empty, if the liquid level within the boiler (12) does not rise despite of operating the pump (38).

11. A steam generating apparatus (10) comprising a boiler (12) for storing liquid and steam, a temperature sensor (24) for sensing a temperature (T) which is indicative of a temperature of the liquid inside the boiler (12), wherein the temperature sensor (24) is arranged outside of the boiler (12), and an electronic control unit (26) which is adapted for executing the method according to claim 1.

12. A domestic appliance comprising the steam generating apparatus according to claim 11.

13. The domestic appliance according to claim 12, wherein the domestic appliance is a coffeemaker, an ironing system, a rise cooker, a steam cleaner, a facial sauna or a cooking device.