Hot water dispenser and method for determining a boiling point of water of a hot water dispenser

Abstract

A hot water dispenser and a method for determining a boiling point of water in the same. The hot water dispenser contains a reservoir, a heating element, and a sensor. The method includes heating water in the reservoir with a first power value of the heating element during a first period of time until a value indicative of a threshold temperature of water is determined; upon reaching the threshold temperature, heating the reservoir water with a second power value of the heating element, which is lower than the first power value, during a second period of time until a water-temperature-rise-per-time value is lower than a first predetermined value; subsequently, increasing the power value of the heating element to a third power value during a third period of time; determining the boiling-point temperature of water by determining the highest temperature of water between the first and third periods of time.

Claims

1. A method for determining a boiling-point temperature of water in a hot water dispenser, the hot water dispenser containing a reservoir, a heating element controlled by a controlling device, and a sensor, the method comprising the steps of: heating up water in the reservoir with a first power value of the heating element during a first period of time until a value indicative of a threshold temperature of water is determined; upon reaching the threshold temperature, heating up water in the reservoir with a second power value of the heating element, which is lower than the first power value of the heating element, during a second period of time; subsequently, increasing the power value of the heating element to a third power value during a third period of time; and determining the boiling-point temperature of water by determining the highest obtained temperature of water between the first period of time and the third period of time.

2. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 1; wherein the third period of time is less than or equal to 10 seconds.

3. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 1; wherein the heating element is shut off as soon as the water temperature rise per time in the third period of time approximates zero.

4. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 1; wherein the second power value of the heating element is 2 to 10 times lower than the first power value of the heating element.

5. The method for determining a boiling point temperature of water used in a hot water dispenser according to claim 4; wherein the second power value of the heating element is 4 times lower than the first power value of the heating element.

6. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 1; wherein the first power value of the heating element is a maximum power value.

7. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 1; wherein the first power value of the heating element is equal to the third power value of the heating element.

8. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 1; wherein the reservoir is open to atmosphere.

9. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 1; wherein the controlling device is an electronic controlling device.

10. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 1; wherein the threshold temperature is in a range of 60° C. and 95° C.

11. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 1; wherein the threshold temperature is approximately 90° C.

12. The method according to claim 1, wherein the method further comprises determining the set point temperature of the hot water dispenser by subtracting a fixed temperature value from the determined boiling-point temperature of water.

13. The method according to claim 12; wherein the subtracted fixed temperature value is two Kelvin.

14. The method for determining a boiling-point temperature of water used in a hot water dispenser according to claim 2; wherein the third period of time is less than or equal to 2 seconds.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically and exemplarily illustrates a hot water dispenser according to the present invention.

(2) FIG. 2 shows a flow chart diagram illustrating a method for determining a boiling point of water in a hot water dispenser according to the present invention.

(3) FIG. 3 illustrates the boiling point detection method, where the heat up for the boiling point detection is shown with the time on the X-axis, and the temperature and the power value on the Y-axis.

DETAILED DESCRIPTION OF EMBODIMENTS

(4) It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, many other elements which are conventional in this art. Those of ordinary skill in the art will recognize that other elements are desirable for implementing the present invention. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein.

(5) The present invention will now be described in detail on the basis of exemplary embodiments.

(6) FIG. 1 schematically and exemplarily illustrates a hot water dispenser according to an embodiment of the present invention. The hot water dispenser comprises a tank assembly 0 which comprises a water reservoir 1 with a cold water inlet tube 2 and a hot water outlet tube 3. The tank assembly 0 also has a sleeve or an insert for a sensor 4, preferably arranged near the bottom of reservoir 1, which is connected to an electronics board 5 via a wire 6 and is used for determining a temperature of water in reservoir 1. A heating element 7 is positioned in reservoir 1, preferably on the bottom of reservoir 1, which is controlled by the firing rate of a triac 8. The triac 8, which is controlled by a power electronics circuit, is connected to the electronics board 5 via a control wire 9 and a supply wire 10. Furthermore, a safety cut off 11 provides safety in case of a controller failure or a dry fire.

(7) A heater assembly comprises a heating element 7, electronics board 5, and two wires 12, 13, wherein the heater assembly is connected to an electric grid via the two wires 12, 13. Furthermore, a push button 14, used for starting the hot water dispenser, is located on the electronics board 5 which is accessible via an enclosure window of the electronics board 5 for a user. In addition, LED's 15, 16, 17 are positioned on the electronic board 5 to be activated in different operation modes preset by the user via the push button 14 and shown on the enclosure front surface of the electronics board 5.

(8) For instance, LED 15 is activated during the boiling point detection. LED 16 is activated during a so called sleep function with reduced temperature settings and LED 17 is activated during heat up or flashing during a shut off failure. A venturi nozzle system for a displacement of the expansion of water during heat up is not shown in FIG. 1, but may be integrated as well. Of course, the shown arrangement of LEDs 15, 16, 17 is just an example and should not be interpreted as limiting in any way.

(9) FIG. 2 shows a flow chart diagram illustrating a method 300 for determining a boiling point of water in a hot water dispenser.

(10) The method 300 comprises a step 310 of heating up water in the reservoir 1 with a first power value of the heating element 7 during a first period of time until a value is determined indicative of a threshold temperature of water.

(11) Upon reaching the threshold temperature, in a step 320 water in the reservoir 1 is heated up with a second power value of the heating element 7 which is lower than the first power value of the heating element 7 during a second period of time until a value indicative of a temperature rise of water per time is lower than a first predetermined value.

(12) Subsequently, in a step 330, the power value of the heating element 7 is increased to a third power value during a third period of time.

(13) In a step 340, the boiling point temperature of water is determined by determining the temperature after the third period of time. Consequently, the highest temperature during first, second, and third period of time is determined as the boiling point temperature.

(14) An effect of the boiling point detection method 300 is shown in FIG. 3, where the heating up for the boiling point detection is shown with the time on the X-axis, and the water temperature ϑ in ° C. and heating power value P in W, respectively, on the Y-axis.

(15) First, water in the reservoir 1 of the hot water dispenser is heated up in step 310 via at least one heating element 7 during a first period of time until a well-defined value ϑ.sub.1 indicative of a threshold temperature of water, for instance 90° C., is determined by the sensor 4. The threshold temperature can vary depending on the different boiling point temperatures which depend on the installation elevations of the hot water dispenser. The heat up until the threshold temperature is reached is accomplished with a first power value P.sub.1, preferably with full power. The measured temperature values are then obtained by integration of the sensor signals over a certain period of time, e.g. in the range of several milliseconds to seconds.

(16) Once the sensor 4 determines the threshold temperature ϑ.sub.1, the power value of the heating element 7 is reduced to a second power value P.sub.2 in a step 320, which is two to ten times, preferably four times, lower than the first power value P.sub.1, during a second period of time.

(17) The heat-up from the threshold temperature close to the adequate boiling temperature happens with the reduced second power value P.sub.2 provided from the power electronics circuit with reduced firing rate until a value indicative of a temperature rise of water per time is lower than a predetermined value. The predetermined value hereby corresponds to approximately zero.

(18) Subsequently, in the step 330, the power value of the heating element 7 is increased to a third power value P.sub.3 during a third period of time. While the power value is increased to the third power value P.sub.3 and no temperature rise is determined, the resultant highest temperature value of the water is valid to be declared as boiling temperature.

(19) Lastly, in step 340, the power of the heating element 7 is shut off and a set point calculation using the determined boiling temperature as maximum follows. The set point temperature of water is determined by subtracting a fixed temperature value, for instance 2 kelvins, from the determined boiling temperature of water.

(20) While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the inventions as defined in the following claims.

LIST OF REFERENCE NUMBERS

(21) 0 water reservoir assembly 1 reservoir 2 cold water inlet tube 3 hot water outlet tube 4 sensor 5 electronic board 6 wire 7 heating element 8 triac 9 control wire 10 supply wire 11 safety cut off 12, 13 wire 14 push button 15, 16, 17 LED P power ϑ temperature t time