Water dispenser with cooling function and control method thereof

Abstract

A water dispenser with cooling function comprises a cooling device for cooling water in an internal path. A temperature sensor detects of the water, and a temperature controller controls the temperature of water in the internal path to a temperature set-point value in accordance with the detected temperature value. A temperature set-point setting means is provided for setting a temperature set-point of the temperature controller. The temperature controller determines a change of the detected temperature value in a predetermined time interval, and the temperature set-point setting means increases the temperature set-point stepwise starting with a normal-state temperature set-point if the detected temperature value does not decrease or remains constant in said predetermined time interval, until a predetermined maximum temperature set-point is set. The water dispenser can be operated reliably and at relatively low costs even at relatively high ambient temperatures.

Description

[0001] BDP-PA-22096-DEWO

[0002] Water dispenser with cooling function and control method thereof FIELD OF INVENTION

[0003] The present invention relates to controlling methods for water dispensing devices, and relates more specifically to a water dispenser with cooling function for cooling water to be dispensed, to a method for controlling the temperature of cooled water in such a water dispenser and a computer program product for such a control method.

[0004] BACKGROUND OF INVENTION

[0005] Water dispensing devices are generally known from the prior art and often include a filtering device to filter input water, such as tap water or water from a water storage container, and dispense filtered water of a particular type, such as water at ambient temperature or water that may be carbonated to a certain degree. Especially for applications at elevated temperatures, such water dispensing devices may include a cooling device, such as a compressor or thermoselectric element, to cool water before it is dispensed.

[0006] At relatively high ambient temperatures, it may occur that the nominal temperature preset by a temperature controller cannot be reached by the cooling device, because the cooling power of the cooling device is not sufficient. This would cause the cooling device to run continuously, resulting in higher costs for operation, unnecessary wear of components but also in higher maintenance costs.

[0007] EP 1 742 001 A2 discloses a method for controlling a refrigerator or freezer in which the compressor is switched on and off depending on the ambient temperature. An evaporator temperature sensor is arranged near the evaporator, and a control unit is configured so that the compressor is switched on when the temperature measured by means of the evaporator temperature sensor exceeds an upper limit value (switch-on value). An ambient temperature sensor is provided which detects the ambient temperature of the refrigerator or freezer, and at higher ambient temperatures the control unit sets a lower switch-on value than at lower ambient temperatures.BDP-PA-22096-DEWO

[0008] US 5 158506 A discloses an apparatus for manufacturing soft-ice-cream and the like by beating and refrigerating at a preset temperature an ice-cream mix supplied from a hopper into refrigeration cylinders. A temperature controller is provided to monitor refrigeration time and refrigeration temperatures of certain components so that, in case the refrigeration time becomes too long due to wrong temperature setting, the preset lower temperature limit is raised to correct a wrong temperature setting.

[0009] EP 3 929 502 Al discloses a cooling system that uses CO2 as a refrigerant. A controller is provided to compute a condenser approach temperature based on a temperature of the coolant exiting the gas cooler / condenser and a temperature of the airflow caused by a fan, to operate the fan to modulate the amount of heat removed from the refrigerant flowing through the gas cooler / condenser in order to maintain the condenser approach temperature at or below a condenser approach set-point, and to automatically adjust the condenser approach set-point in response to the amount of heat removed from the refrigerant being insufficient to maintain the condenser approach temperature at or below the condenser approach set-point.

[0010] US 2017 030 7288 Al discloses a method for controlling the cooling of a water dispenser in multiple stages, using n predetermined ever decreasing temperatures. Upon reaching a first predetermined temperature, the cooling system stops for a predetermined time period before resuming operation. Then, the temperature set-point is iteratively lowered, and operation of the cooling system resumed and stopped again for a predetermined time period, to thereby reach a very low target temperature. If the nth predetermined temperature cannot be reached, the cooling system repeats the previous stages and tries to reach the n-l-th temperature.

[0011] SUMMARY OF INVENTION

[0012] It is an object of the present invention to provide a water dispenser with cooling function that can be operated reliably and at relatively low costs even at relatively high ambient temperatures. It is a further object of the present invention to provide a method for controlling the temperature of cooled water in such a water dispenser, and a corresponding computer program product for such a method.

[0013] These problems are solved by a water dispenser with cooling function as claimed in claim 1, by a method for controlling the temperature of cooled water in such a water dispenser as claimedBDP-PA-22096-DEWO

[0014] in claim 8, and by a computer program as claimed in claim 15. Further advantageous embodiments are the subject-matter of the dependent claims.

[0015] According to the present invention there is provided a water dispenser with cooling function, comprising a housing having an internal path for cooled water, which is disposed in the housing, a cooling device for cooling the water in the internal path, a temperature sensor for detecting a temperature corresponding to a temperature of water in the internal path and outputting a detected temperature value, and a temperature controller, configured for controlling the temperature of water in the internal path to a temperature set-point value in accordance with the detected temperature value by controlling an operation of the cooling device, wherein a temperature set-point setting means is provided for setting a temperature set-point of the temperature controller. According to the present invention the temperature controller is further configured to determine a change of the detected temperature value in a predetermined time interval, wherein the temperature set-point setting means is configured to increase the temperature set-point stepwise starting with a normal-state temperature set-point if the detected temperature value does not decrease or remains constant in said predetermined time interval, until a predetermined maximum temperature set-point is set.

[0016] Determining that the temperature value corresponding to the temperature of water in the internal path for cooled water has decreased during the predetermined time period enables to determine whether the temperature set-point can be reached. If the temperature value does not decrease during the predetermined time period this is a clear indication that the cooling power of the cooling device is not sufficient under the conditions prevailing and that the temperature setpoint could also not be reached if the cooling device is operated for a much longer time period resulting in unnecessary high power consumption. In such a case, the temperature set-point is automatically increased and over-written by a next higher temperature set-point. This loop is repeated iteratively until it is determined that the temperature value has decreased during the predetermined time period, which is a clear indication that the cooling power of the cooling device is sufficient under the conditions prevailing and that the temperature set-point could be reached. In this way, an excessively long operation of the cooling device without reaching the temperature set-point can be avoided, which helps to prevent overloads and thus to reduce maintenance costs and also enables an operation at lower power consumption.BDP-PA-22096-DEWO

[0017] The control method starts with a normal-state temperature set-point that may be a predetermined temperature set-point set when the water dispensing device is turned on or switched from an idle mode (e.g. during night-time) to a standard operation mode (e.g. during normal office hours or day-time). The normal-state temperature set-point may also be input by a user when the water dispensing device is turned on or switched from the idle mode to the standard operation mode, and may also be varied and input by a user as an input cooling temperature set-point during operation of the water dispensing device while the control method is performed. This input cooling temperature set-point may be different to the normal-state temperature set-point, depending on individual preferences of a user.

[0018] According to a further embodiment, the temperature controller is configured as an on-off controller having a first output state in which the cooling device is switched on and the detected temperature value is higher than the temperature set-point, and a second output state in which the cooling device is switched off and the detected temperature value is lower than or equal to the temperature set-point. An on-off controller enables a very quick, reliable and cost-efficient operation of the cooling device, in particular for compressor-type cooling devices.

[0019] According to a further embodiment, the temperature controller is configured to output an error signal if the detected temperature value does not reach the predetermined maximum temperature set-point in a predetermined time interval. The error signal may be used to trigger a re-start of the water dispensing device, preferably after expiry of a predetermined time period, to avoid a continuous operation of the cooling device over a long time period. Operation of the water dispensing device may then be started again with a standard initial predetermined temperature set-point or a higher temperature set-point, which should be lower than a predetermined maximum temperature set-point corresponding to a relatively high temperature where operation of the cooling device does not make sense, e.g. if the maximum temperature set-point more or less corresponds to the ambient temperature of the water dispensing device.

[0020] According to a further embodiment, the temperature set-point setting means is further configured to, after the predetermined time interval has elapsed, overwrite the temperature setpoint with the normal-state temperature set-point to restore the normal-state temperature setpoint before the temperature controller starts a new cycle of controlling the temperature of water in the internal path. Hence, if the conditions are such that the cooling power of the cooling device is not sufficient to reach the temperature set-point, a continuous operation of the coolingBDP-PA-22096-DEWO

[0021] device is prevented, to thereby avoid overloads. Instead, operation of the cooling device is resumed with the normal-state temperature set-point, which may also be adjusted to a higher temperature value based on the input by a user.

[0022] According to a further embodiment, the temperature set-point setting means is further configured, if the detected temperature value has decreased and reached the temperature setpoint in said predetermined time interval, to determine whether the detected temperature value is smaller than or equal to a input cooling temperature set-point, to continue operating the cooling device until the detected temperature value is smaller than or equal to the input cooling temperature set-point, and to overwrite the input cooling temperature set-point stepwise with a higher input cooling temperature set-point after a second predetermined time interval has expired.

[0023] Accordingly, the cooling device remains turned-on over a second time interval, and if this predetermined second time interval has expired but still the input cooling temperature set-point has not been reached, the method incrementally increases the input cooling temperature setpoint, e.g. with a fixed increment of 1 °C, and the method returns to the step of determining whether the temperature value corresponding to the temperature of water in the internal path for cooled water has decreased during the predetermined time period. An excessive continuous operation of the cooling device can thus be prevented and the control method is resumed with the next higher input temperature set-point. This loop is performed until it is determined that the temperature value has decreased and the input temperature set-point has been reached.

[0024] The increase of the input cooling temperature set-point may be performed by overwriting the previous input cooling temperature set-point in the controlling unit by means of the temperature set-point setting means with the next higher input cooling temperature set-point

[0025] According to a further embodiment, the water dispenser further comprises a temperature sensor for detecting an ambient temperature, for outputting a detected ambient temperature value, wherein the temperature set-point setting means is further configured to readjust the normalstate temperature set-point if the detected ambient temperature value has changed, in particular if the detected ambient temperature value has decreased. Accordingly, if the ambient temperature has increased significantly, in which case it might be likely that the cooling power of the cooling device is not sufficient to reach a relatively low temperature set-point, operationBDP-PA-22096-DEWO

[0026] of the cooling device may be resumed or continued at a higher temperature set-point to reduce overall power consumption. On the other hand, reducing the temperature set-point in case of a decrease in ambient temperature will help to ensure that the cooling effect of the water dispenser matches the standard performance expected by a user.

[0027] According to a further embodiment, the temperature controller is configured as an on-off controller with hysteresis behavior.

[0028] According to a further aspect of the present invention there is provided a method for controlling the temperature of cooled water in a water dispenser with cooling function, comprising a housing having an internal path for cooled water, which is disposed in the housing, a cooling device for cooling the water in the internal path, a temperature sensor for detecting a temperature value corresponding to a temperature of water in the internal path and for outputting a detected temperature value, and a temperature controller, said method comprising: initially setting a temperature setpoint value of the temperature controller to a normal-state set temperature value, detecting a temperature value of cooled water in the internal path, controlling the temperature of cooled water in the internal path to a temperature setpoint in accordance with the detected temperature value by controlling an operation of said cooling device, determining a change in the detected temperature value is determined in a predetermined time interval, and stepwise increasing the temperature setpoint if the detected temperature value does not decrease or remains constant in said predetermined time interval, until a predetermined maximum temperature setpoint is set.

[0029] OVERVIEW ON DRAWINGS

[0030] Hereinafter, the invention will be disclosed in an exemplary manner with reference to the annexed drawings, wherein

[0031] Fig. 1 is a schematic block diagram of a water dispensing device configured for performing the cooling method according to the present invention; and

[0032] Fig. 2 is a schematic flow diagram of a method for controlling a cooling device of a water dispensing device according to the present invention.BDP-PA-22096-DEWO

[0033] Throughout the description, the same or similar elements and the elements having same or similar functions are denoted by like reference numerals. The embodiments described herein with reference to the drawings are explanatory, illustrative, and used to generally understand the present disclosure. The embodiments shall not be construed to delimit the present disclosure.

[0034] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0035] As shown in Fig. 1, the water dispensing device 1 comprises a housing 30 in which the most important components may be installed. The water dispensing device 1 may be installed in a building or office space and a water inlet 10 may be connected to a water supply line or water tap of the building or office space via an inlet tube 11 for continuously supplying raw water upon demand, or the water dispensing device 1 may be connected to an external water reservoir or include an internal water reservoir, and includes a pump for supplying raw water from such a water reservoir. At the inlet-side of the water dispensing device 1 there may be a provided a central filtering unit, which may be a bacteria-proof filter with hollow fiber membrane (microfiltration) and a carbon block as pre-filter.

[0036] The water dispensing device 1 is configured to dispense water of at least one type, namely cooled water, but may also dispense water of selected other types, such as water at ambient temperature or water that may be carbonated to a certain degree. Hence, for applications at elevated temperatures the water dispensing device 1 includes a cooling device 2 to cool water in the internal water path 15 before it is dispensed. The cooling device 2 is preferably a compressor, but may also be embodied as an electric cooling device, such as a thermo-electric element. To simplify the following description, other internal water paths for different types of water to be dispensed are omitted in Fig. 1.

[0037] The cooled water from the internal water path 15 is dispensed via the cooled water outlet 12 and an outlet tube 13. At least one three-way valve 21 is provided inside the housing 30 to control the internal flow of water, preferably of different types of water, in the at least one internal water path 15 of the water dispensing device 1. At least one recirculation path 20 may be provided inside the housing 30, in order to circulate water that has stagnated in the at least one internal water path 15 via a sterilization or filtering unit, to prevent the build-up of biofilms or germ growth.BDP-PA-22096-DEWO

[0038] At a proper location inside the housing 30 there is provided a temperature sensor 5 for detecting a temperature corresponding to the temperature of cooled water in the internal path 15. The temperature sensor 5 may be immersed into the cooled water, or may be disposed directly at or near an internal water conducting tube, e.g. directly in or on a housing of the cooling device 2, near or at an outlet of the cooling device, on a heat-sink used for heat-exchange between the cooling device 2 (or an output thereof) and the internal path 15.

[0039] In a preferred embodiment, the water dispensing device 1 is driven by means a power supply 32 and operated under the central control of a controlling unit 36 that may receive input commands of a user via an input unit 31, such as a touch panel that may visualize a graphical user interface (GUI) or a keyboard, for controlling the whole operation of the water dispensing device 1. The functions of the controlling unit 36 may also be performed by several interconnected controllers. The temperature sensor 5 is connected to the controlling unit 36 to input a temperature value corresponding to the temperature of water in the internal path 15 for cooled water. As explained below in more detail, a temperature rate-of-change sensor 35 is provided, which is preferably integrated into the controlling unit 36. The sensor 35 is configured to determine or calculate a rate-of-change of the detected temperature on the basis of the temperature values provided by the temperature sensor 5. Or simpler, the sensor 35 may be configured to detect a change of temperature corresponding to the temperature of water in the internal path 15 for cooled water in a predetermined time period. The controlling unit 36 is connected to the cooling device 20 to control the operation of the cooling device and the temperature of water in the internal path 15 for cooled water, as outlined below.

[0040] As shown in Fig. 1, an additional temperature sensor 4 may be provided outside or on the housing 30 in order to detect the ambient temperature of the water dispensing device 1, e.g. the temperature inside a building or office space. The additional temperature sensor 4 is also connected to the controlling unit 36.

[0041] The controlling unit 36 is preferably embodied as a two-point controller, namely a discontinuous controller that works with the two output states ON and OFF in accordance with a control program executed by the controlling unit 36. Such a controller may consist basically of a comparator and a subtractor for the reference variable (set-point temperature value) and the control variable (temperature value corresponding to the temperature of water in the internalBDP-PA-22096-DEWO

[0042] path 15 for cooled water). The controller's output variable is the manipulated variable, which is input to the cooling device 2 via e.g. a power stage driving the cooling device 2.

[0043] According to the present invention, the controlling unit 36 is integrated with the controlled system to form a control loop. In operation, after the temperature set-point has been reached, the detected temperature constantly fluctuates around the temperature set-point. The main advantage of a two-point controller is generally that it can be implemented and operated at low costs. Moreover, a two-point controller is a fast controller, its main strength being its simplicity and reliable long-term operation.

[0044] Hereinafter, a preferred embodiment of a method for controlling the temperature of cooled water in a water dispenser 1 with cooling function as outlined above will be described with reference to Figs. 1 and 2.

[0045] In a first step (‘Start’) that is performed e.g. when the water dispensing device 1 is turned on or switched from an idle mode (e.g. during night-time) to a standard operation mode (e.g. during normal office hours or day-time), the water dispensing device 1 including the controlling unit 36 is initialized and a predetermined temperature set-point for the cooled water to be dispensed is set. This initial temperature set-point may be fixed, but may also be dependent on preferences of a user input e.g. via input device 31 and stored in an internal memory. The initial temperature set-point may be a value in the temperature range between 4 °C and 8 °C.

[0046] A user may also input an input temperature set-point, e.g. when the water dispensing device 1 is turned on or switched from an idle mode to a standard operation mode in step ‘Start’. This input temperature set-point may be different to the initial temperature set-point and is also stored in an internal memory.

[0047] The initial temperature set-point may also be varied and input by a user as an input cooling temperature set-point during operation of the water dispensing device 1, while the control method shown in Fig. 2 is performed, as outlined in the following in more detail.

[0048] The temperature sensor 5 detects a temperature and inputs a temperature value corresponding to the temperature of water in the internal path 15 for cooled water (hereinafter also named the ‘detected temperature’) to the controlling unit 36. When the controlling unit determines thatBDP-PA-22096-DEWO

[0049] the current temperature exceeds a temperature set-point, the cooling device 2 is turned-on, to thereby cool the internal water path 15 for cooled water. The controlling unit 36 constantly monitors the temperature value corresponding to the detected temperature, and the temperature rate-of-change sensor 35 constantly monitors the rate-of-change of the detected temperature in step SI, or simply the change of the detected temperature over a predetermined time period, which may be in the range between 5 min and 20 min, more preferably in the range between 7.5 min and 15 min and even more preferably in the range between 9 min and 11, e.g. 10 min, which will depend in particular on the desired cooling characteristics of the water dispending device 1. The temperature rate-of-change sensor 35 may determine an average rate-of-change (or change) of the detected temperature, e.g. by sampling temperature values at fixed time intervals over the predetermined time period and inputting an average value of these temperature values to the controlling unit 36, which may be a positive value, a negative value or basically be zero.

[0050] Under normal conditions, when the cooling power of the cooling device 2 is sufficient and the ambient temperature not too high, the temperature detected by temperature sensor 5 will decrease, resulting in a negative rate-of-change of the temperature value corresponding to the detected temperature, i.e. a decrease of the detected temperature.

[0051] If such a negative rate-of-change of the temperature value (decrease in temperature) is determined by the temperature rate-of-change sensor 35 in step SI, the method proceeds with step S4 and the cooling temperature set-point is kept constant. On the other hand, if such a negative rate-of-change of the temperature value (decrease in temperature) is not determined by the temperature rate-of-change sensor 35 in step SI, the method proceeds with step S2, where it is first checked, whether the current cooling temperature set-point is larger than or equal to a predetermined maximum cooling temperature, which is set initially to a reasonable value justifying a cooling operation at all, and which may be in the range e.g. between 4 °C and 8 °C.

[0052] This predetermined maximum cooling temperature may also be dependent on the ambient temperature prevailing when initializing the water dispensing device 1. E.g. if the ambient temperature is reasonable, such as of the order of between 20 °C and 25 °C, the predetermined maximum cooling temperature may be relatively low, e.g. of the order of 4 °C to 8 °C, whereas if the ambient temperature is relatively high, such as of the order of between 25 °C and 30 °CBDP-PA-22096-DEWO

[0053] or above, the predetermined maximum cooling temperature may be relatively high, e.g. of the order of 8 °C to 12 °C or even higher, to avoid a too low temperature of the dispensed water.

[0054] A reasonable safety margin may be provided around the zero-point in step SI. E.g. a temperature change is only considered as positive (or negative), if it exceeds or is lower than 0 °C plus a safety margin, that may be of the order of e.g. 0.2 °C or 0.1 °C.

[0055] If it is determined in step S2, that the current cooling temperature set-point is larger than or equal to the predetermined maximum cooling temperature, then the method proceeds with step S3, where the cooling temperature set-point is increased for further operation of the control loop. This increase of the cooling temperature set-point is preferably performed incrementally with fixed increments, e.g. with a fixed increment of 1 °C. The increase of the cooling temperature set-point is performed by overwriting the previous cooling temperature set-point in the controlling unit 35 with a new temperature set-point by means of the temperature setpoint setting means 36.

[0056] After step S3, the method returns to step SI to determine whether a negative rate-of-change of the temperature value (or decrease in temperature over a predetermined time period) occurs at the now higher temperature set-point. If in step S 1 a negative rate-of-change of the temperature value (or decrease in temperature over a predetermined time period) is again not determined by the temperature rate-of-change sensor 35, the method proceeds with step S2, where it is first checked, whether the current cooling temperature set-point is larger than or equal to a predetermined maximum cooling temperature, and if not, the method proceeds with step S3 to increase again the cooling temperature set-point by the fixed increment.

[0057] The loop of steps SI to S3 is followed until either a negative rate-of-change of the temperature value (or decrease in temperature over a predetermined time period) is determined by the temperature rate-of-change sensor 35 in step SI or until it is determined in step S2 that the current cooling temperature set-point is larger than or equal to the predetermined maximum cooling temperature, in which case the method proceeds with step S9 to output an error signal that may be displayed on a display, e.g. of the input device 31, to inform the user that the desired cooling function cannot be implemented, which may cause the user to switch off the cooling function of the water dispensing device 1 or input a higher input temperature set-point. Or, outputting the error signal in step S9 may trigger a standard operation mode of the waterBDP-PA-22096-DEWO

[0058] dispensing device 1 without cooling function, and after the expiry of a predetermined time period of e.g. 2-4 hours the controlling unit 36 is reset or initialized again and the control method is resumed at step ‘Start’, as outlined above.

[0059] Returning again to step S 1 , after a negative rate-of-change of the temperature value (or decrease in temperature over a predetermined time period) has been determined by the temperature rate-of-change sensor 35 in step SI and the method has proceeded with step S4 to keep the cooling temperature set-point constant, the method then proceeds with step S5, where it is determined whether the current temperature is less than or equal to the cooling temperature set-point. If this is not yet the case, but a negative rate-of-change of the temperature value (decrease in temperature) continues to be determined in step SI, the loop of steps SI, S4 and S5 is performed until it is determined in step S5, where it is determined that the current temperature is less than or equal to the cooling temperature set-point. The method then proceeds with step S6, where it is determined whether the value of the current temperature is less than or equal to the input cooling temperature set-point described above with reference to step ‘ Start’ .

[0060] If it is determined in step S6 that the value of the current temperature is less than or equal to the input cooling temperature set-point, then the method proceeds with step S 10 and tums-off the cooling device 2 for a predetermined time period, which may be of the order of e.g. 15 min to 20 min. After expiry of this predetermined time period, the controlling unit 36 checks the current value corresponding to the temperature of water in the internal path 15 for cooled water and decides, whether operation of the cooling device 2 shall be resumed or not. More specifically, operation of the cooling device 2 may be resumed if a difference between the current value corresponding to the temperature of water in the internal path 15 for cooled water and a set-point temperature value exceeds a predetermined threshold value.

[0061] On the other hand, if it is determined in step S6 that the value of the current temperature is not less than or equal to the input cooling temperature set-point, then the method proceeds with step S7, where the cooling device 2 remains turned-on over a predetermined time period. If this predetermined time period has expired (Y) but still the detected temperature has not reached the input cooling temperature set-point, the method proceeds with step S8, where the input cooling temperature set-point is increased by a fixed increment, e.g. by a fixed increment of 1 °C. The increase of the input cooling temperature set-point is performed by overwriting theBDP-PA-22096-DEWO

[0062] previous input cooling temperature set-point in the controlling unit 35 with a new (higher) input cooling temperature set-point by means of the temperature set-point setting means 36. The method then proceeds with step S 1.

[0063] The loop of steps SI, S4 to S8 is performed iteratively, until it is determined in step S6 that the current temperature value is less than or equal to the input cooling temperature set-point and the cooling device 2 is turned-off in step S10, or until a decrease in temperature is not detected in step SI and it is detected in step S2 that the current cooling temperature set-point is larger than or equal to a predetermined maximum cooling temperature, in which case an error signal is output in step S9 and the cooling device 2 is turned-off for a predetermined time period, before resuming operation with step ‘Start’, as outlined above.

[0064] In the control method, determining a change of the detected temperature in a predetermined time interval is used to determine whether a temperature set-point can be reached. If not, the temperature set-point is automatically overwritten by a higher temperature set-point to protect the cooling device. This is done iteratively until it is determined that a temperature set-point has been be reached that may be identical with the initial temperature set-point or input cooling temperature set-point and is lower than or equal to a maximum temperature set-point. If the temperature set-point has been adjusted to a maximum temperature set-point but the detected temperature still cannot reach the temperature set-point, an error signal is output and operation of the cooling device may be interrupted for a predetermined time period, after the expiry of which operation of the cooling device and control method is resumed with a predetermined initial temperature set-point or an input cooling temperature set-point input by a user.

[0065] If the ambient temperature changes, the predetermined initial temperature set-point may be reset and operation may be resumed with step ‘ Start’ . If the controlling unit cannot reach a maximum temperature set-point either, an error signal is output and an error message may be displayed.

[0066] With the afore-mentioned control method, a water dispenser with cooling function can be operated reliably even at relatively high ambient temperatures, because the temperature setpoint is increased incrementally until a maximum temperature set-point has been adjusted or the temperature set-point has been reached. Operation of the water dispenser can be controlled at relatively low costs, because the costs for maintenance and repair of expensive components,BDP-PA-22096-DEWO

[0067] such as the cooling device, can be reduced as overloads caused by a too long operation of the cooling device while not reaching the temperature set-point can be avoided.

[0068] As will become apparent from the above disclosure, the control method can be performed with different types of cooling devices, including thermo-electric cooling components. The control method can be performed with a certain hysteresis, which can help to further reduce the frequency of tuming-on and -off operation of the cooling device.BDP-PA-22096-DEWO

[0069] LIST OF REFERENCE NUMERALS

[0070] 1 water dispensing device

[0071] 2 cooling device, in particular compressor

[0072] 3 controller

[0073] 4 sensor for ambient temperature

[0074] 5 sensor for temperature of cooled water

[0075] 10 water inlet

[0076] 11 inlet tube

[0077] 12 cooled water outlet

[0078] 13 outlet tube

[0079] 15 internal water path

[0080] 20 internal recirculation path for cooled water

[0081] 21 three-way valve

[0082] 30 housing

[0083] 31 input device

[0084] 32 power supply

[0085] 35 temperature rate-of-change sensor

[0086] 36 controlling unit / temperature set-point setting means

[0087] 51 decrease in temperature detected?

[0088] 52 cooling temperature set-point > maximum cooling temperature? 53 increase cooling temperature set-point

[0089] 54 cooling temperature set-point kept constant

[0090] 55 T < cooling temperature set-point?

[0091] 56 T < input cooling temperature set-point?

[0092] 57 predetermined time-period expired?

[0093] 58 increase input cooling temperature set-point

[0094] 59 output error signalBDP-PA-22096-DEWO

[0095] S10 cooling device is turned off

Claims

BDP-PA-22096-DEWOCLAIMS1. A water dispenser (1) with cooling function, comprisinga housing (30) having an internal path (15, 20) for cooled water, which is disposed in the housing,a cooling device (2) for cooling the water in the internal path (15, 20),a temperature sensor (5) for detecting a temperature corresponding to a temperature of water in the internal path (15, 20) and outputting a detected temperature value, anda temperature controller (3), configured for controlling the temperature of water in the internal path (15, 20) to a temperature set-point value in accordance with the detected temperature value by controlling an operation of the cooling device (2), whereina temperature set-point setting means (36) is provided for setting a temperature set-point of the temperature controller (3),characterized in that the temperature controller (3) is further configured to determine a change of the detected temperature value in a predetermined time interval, whereinthe temperature set-point setting means (36) is configured to increase the temperature set-point stepwise starting with a normal-state temperature set-point if the detected temperature value does not decrease or remains constant in said predetermined time interval, until a predetermined maximum temperature set-point is set.

2. The water dispenser (1) with cooling function as claimed in claim 1, wherein the temperature controller (3) is configured as an on-off controller havinga first output state in which the cooling device (2) is switched on and the detected temperature value is higher than the temperature set-point, anda second output state in which the cooling device (2) is switched off and the detected temperature value is lower than or equal to the temperature set-point.

3. The water dispenser (1) with cooling function as claimed any of the preceding claims, wherein the temperature controller (3) is configured to output an error signal (S9) if the detected temperature value does not reach the predetermined maximum temperature set-point in a predetermined time interval.

4. The water dispenser (1) with cooling function as claimed in claim 3, whereinBDP-PA-22096-DEWOthe temperature set-point setting means (36) is further configured to, after the predetermined time interval has elapsed, overwrite the temperature set-point with the normalstate temperature set-point (S7) to restore the normal-state temperature set-point before the temperature controller (3) starts a new cycle of controlling the temperature of water in the internal path (15, 20).

5. The water dispenser (1) with cooling function as claimed any of the preceding claims, wherein the temperature set-point setting means (36) is further configured, if the detected temperature value has decreased and reached the temperature set-point in said predetermined time interval,to determine whether the detected temperature value is smaller than or equal to an input cooling temperature set-point,to continue operating the cooling device (2) until the detected temperature value is smaller than or equal to the input cooling temperature set-point (S6), andto overwrite the input cooling temperature set-point stepwise with a higher input cooling temperature set-point (S8) after a second predetermined time interval has expired (S7).

6. The water dispenser (1) with cooling function as claimed in any of the preceding claims, further comprising a temperature sensor (4) for detecting an ambient temperature, for outputting a detected ambient temperature value, whereinthe temperature set-point setting means (36) is further configured to readjust the input cooling temperature set-point to a normal-state temperature set-point if the detected ambient temperature value has changed, in particular if the detected ambient temperature value has decreased.

7. The water dispenser (1) with cooling function as claimed in any of the preceding claims, wherein the temperature controller (3) is designed as an on-off controller with hysteresis behavior.

8. A method for controlling the temperature of cooled water in a water dispenser (1) with cooling function, comprising a housing (30) having an internal path (15, 20) for cooled water, which is disposed in the housing, a cooling device (2) for cooling the water in the internal path (15, 20), a temperature sensor (5) for detecting a temperature value corresponding to aBDP-PA-22096-DEWOtemperature of water in the internal path (15, 20) and for outputting a detected temperature value, and a temperature controller (3), said method comprising:initially setting a temperature set-point value of the temperature controller (3) to a normal-state set temperature value,detecting a temperature value of cooled water in the internal path (15, 20), controlling the temperature of cooled water in the internal path (15, 20) to a temperature set-point in accordance with the detected temperature value by controlling an operation of said cooling device (2),determining a change in the detected temperature value is determined in a predetermined time interval, andstepwise increasing the temperature set-point if the detected temperature value does not decrease or remains constant in said predetermined time interval, until a predetermined maximum temperature set-point is set.

9. The method as claimed in claim 8, wherein the temperature controller (3) is designed as an on-off controller havinga first output state in which the cooling device (2) is switched on and the detected temperature value is higher than the temperature set-point, anda second output state in which the cooling device (2) is switched off and the detected temperature value is lower than or equal to the temperature set-point.

10. The method as claimed in claim 8 or 9, wherein further comprisingoutputting an error signal (S9) if the detected temperature value does not reach the predetermined maximum temperature set-point in a predetermined time interval.

11. The method as claimed in claim 10, further comprising, after the predetermined time interval has elapsed, overwriting the temperature set-point with the normal-state temperature set-point (S7) to restore the normal-state temperature setpoint before starting a new cycle of controlling the temperature of water in the internal path (15, 20).

12. The method as claimed in any of claims 8 to 11, further comprisingdetecting an ambient temperature value corresponding to an ambient temperature, andBDP-PA-22096-DEWOreadjusting the normal-state temperature set-point if the detected ambient temperature value has changed, in particular if the detected ambient temperature value has decreased.

13. The method as claimed in any of claims 8 to 12, further comprising, if the detected temperature value has decreased and reached the temperature set-point in said predetermined time interval,determining whether the detected temperature value is smaller than or equal to an input cooling temperature set-point,continuing operating the cooling device (2) until the detected temperature value is smaller than or equal to the input cooling temperature set-point (S6), andoverwriting the input cooling temperature set-point stepwise with a higher input temperature set-point (S8) after a second predetermined time interval has expired (S7).

14. The method as claimed in any of claims 8 to 13, wherein the temperature controller (3) is designed as an on-off controller with hysteresis behavior.

15. A computer program product comprising instructions which, when the program is executed by a temperature controller (3) of a water dispenser (1), cause the temperature controller (3) to carry out the steps of the method of any of claims 8 to 14.

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