HEATING DEVICE FOR HEATING WATER, AND WATER CONDUCTING APPLIANCE COMPRISING A HEATING DEVICE

A heating device for heating water, having a container having an inlet channel and an outlet channel, two spaced-apart plates which act as electrodes and each comprise an electrical connection for connection to an electrical voltage source for generating a current flow through the water located between the plates, wherein at least one plate is mounted movably in order to change the distance between the plates and thereby the volume provided between the plates. A water-conducting device such as a washing machine, dishwasher or hot beverage maker, includes a flow conducting system and a heating device arranged therein, as described above.

TECHNICAL FIELD

The disclosure relates to a heating device for heating water, comprising a container having an inlet channel and an outlet channel.

BACKGROUND

Water-conducting devices, such as washing machines, dishwashers or beverage makers, require heated water during operation, which is provided by means of a heating element or an instantaneous water heater mounted in the treatment container. In this case, electrical resistance heating elements are used which heat up when connected to electrical current and, due to contact with the water, transfer the heat into the water. This means that a heat transfer from the heating element to the water always takes place, which is lossy or prolongates heating of the water.

DE 10 2014 217 842 A1 discloses a heating device for a beverage maker in the form of an instantaneous water heater.

SUMMARY

The object of the disclosure is to provide an improved heating device for efficient and safe operation when heating water.

According to the disclosure, this object is achieved, inter alia, by a heating device having the features of independent claim1and by a water-conducting device according to claim12. Advantageous embodiments and developments of the disclosure can be found in the respective dependent claims.

An advantage that can be achieved with the disclosure is that heating is very precise and the temperature specified by the user or the process control is maintained very precisely with extremely small deviations. Furthermore, the water is heated more quickly than with conventional instantaneous water heaters, hotplates, or immersion heaters.

For this purpose, the heating device comprises two spaced-apart plates within the container, which act as electrodes and each comprise an electrical connection for connection to an electrical voltage source in order to generate a current flow through the water located between the plates. At least one plate is mounted movably in order to change the distance between the plates and thereby the volume provided between the plates. The electrodes conduct the voltage applied to the plates directly into the liquid so that an electrical current flows through the water which is located in the spanned space between the two plates. Due to the electrical conductance or resistance of water, it is heated without a heat transfer from a heated body to the water taking place. The water is thus heated directly. Preferably, an AC voltage in the frequency range of the usual mains frequency is used on the electrodes in order to prevent electrolysis, i.e., to reduce it or not allow it to occur. The conductance is changed with the variable distance between the plates, wherein the electric conductance between the plates increases at a smaller distance and decreases at a greater distance. The conductance is furthermore strongly dependent on the properties or composition of the water, in particular on mineral additives, so that the distance between the plates can be adjusted accordingly in order to enable the desired electrical current flow. The plates are preferably spaced parallel to one another. Since the plates act as electrodes, they must have only a low transition resistance to the water so that they preferably consist of graphite or have a graphite surface. Overall, the heating device is designed for use in a water-conducting device, preferably for use in a washing machine, a dishwasher, or a hot beverage maker.

In an advantageous embodiment, the heating device comprises a drive means for moving the movable plate, and a control device for controlling or activating and deactivating the drive means. The distance can thus be set automatically, depending on the process requirements of the device in which the heating device is inserted.

In a preferred development, the heating device comprises a detection means for detecting the conductance of the water located between the plates. The control device is preferably configured to set the distance of the plates from one another as a function of the detected conductance. The conductance is furthermore strongly dependent on the properties or composition of the water, in particular on mineral additives and the temperature, so that the distance between the plates can be adjusted automatically as a function of the properties and process requirements.

In an overall expedient embodiment, the drive means comprises a controllable motor/actuator with a lever mechanism for connecting the motor/actuator to the movable plate. This is a particularly simple variant because the actuator must be arranged outside the reactor container, wherein coupling and guidance of the movable plate take place by means of the lever transmission.

In another, overall advantageous embodiment, the drive means comprises a controllable motor with a spindle coupled thereto for connecting or coupling the motor to the movable plate. A plurality of different distances can thus be set in a simple manner. In combination with the detection of the conductance, a very delicate control of the current flow can be provided. Guidance of the movable plate can be provided by means of a lever mechanism or a rail guide in order to provide a linear movement transverse to the surface area of the plate.

In an overall expedient embodiment, the container volume is in the range of 50 ml to 2000 ml. This is sufficient for a heating device of the aforementioned type for most applications in water-conducting household appliances and can be accommodated in the corresponding devices without notable constructive effort.

In a further, overall expedient embodiment, the plate size has a value in the range of 10 cm2 to 500 cm2, wherein the distance of the plates is configured to be variable in a range of 5 cm to 0.5 cm.

The disclosure further relates to a water-conducting device such as a washing machine, dishwasher or hot beverage maker, comprising a flow conducting system and a heating device arranged therein according to one of the above-mentioned embodiments.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG.1schematically shows the heating device9in a first embodiment. This device9comprises a container90having an inlet channel91and an outlet channel92and two spaced-apart plates93,94in the container90, which act as electrodes and each comprise an electrical connection for connection to an electrical voltage source102for generating a current flow I through the water W located between the plates, wherein at least one plate94is mounted movably in order to change the distance between the plates93,94and thus the water volume provided between the plates93,94.FIG.1shows the situation in which the plates93,94have a large distance A from one another. The movable plate94is guided in the container90by means of a lever mechanism96. A drive means95serves to drive the lever mechanism in order to move the plate94in order to change the parallel distance between the plate94and the stationary plate93. The control device100is configured to switch the corresponding AC voltage to the plates93,94and to activate the drive means95in order to set the distance A of the plates93,94to one another. With the detector98, such a conductivity detector, sensor, probe or equivalent detection means, the conductance of the liquid W located in the container can be detected and supplied to the control device100. The control device100can activate the drive means95on the basis of the detected conductance and the defined requirements for water heating in order to set the distance A such that an electrical current flow I is established which leads to the desired heating of the water W. In this case, the heating device9is designed as an instantaneous water heater, but it can also be designed as a boiler. Due to the AC voltage applied to the plates93.94, the current I is an alternating current with the same frequency.

FIG.2shows the heating device9according to the embodiment described above, but with a changed position of the movable plate94. Here, the plate94is moved in the direction of the stationary plate93so that the two plates93,94are located at a smaller distance A from one another, relative to the situation outlined inFIG.1. In this case, the lever mechanism96serves to convert the rotational movement of the drive means95into a linear movement and to guide the movable plate94in a stable manner.

FIG.3schematically shows the heating device9in a second embodiment. This device9comprises a container90having an inlet channel91and an outlet channel92and two spaced-apart plates93,94in the container90, which act as electrodes and each comprise an electrical connection for connection to an electrical voltage source102for generating a current flow I through the water W located between the plates93,93, wherein at least plate94is mounted movably in order to change the distance A between the plates93,94and thus the water volume provided between the plates93,94.FIG.1shows the situation in which the plates93,94have a large distance from one another. The movable plate94is guided in the container90by means of a spindle97. A drive means95serves to drive the spindle97in order to move the plate94in order to change the parallel distance A between the plate94and the stationary plate93. In the example shown, the spindle97is designed as a stationary threaded rod which is attached to the rear side of the movable plate94. The motor95drives a corresponding driver which can move the threaded rod97linearly. A further guide means99serves to stabilize the movable plate94. The control device100is configured to switch the corresponding AC voltage to the plates93,94and to activate the drive means95in order to set the distance A of the plates93,94to one another. With the detection means98, the conductance of the liquid W located in the container can be detected and supplied to the control device100. The control device100can activate the drive means95on the basis of the detected conductance and the defined requirements for water heating in order to set the distance such that an electrical current flow I is established which leads to the desired heating of the water W. In this case, the heating device9is designed as an instantaneous water heater, but it can also be designed as a boiler. Due to the AC voltage applied to the plates93.94, the current I is an alternating current with the same frequency.

FIG.4shows the heating device9according to the embodiment described above, but with a changed position of the movable plate94. Here, the plate94is moved in the direction of the stationary plate93so that the two plates93,94are located at a smaller distance A from one another, relative to the situation outlined inFIG.3. In this case, the spindle drive97serves to convert the rotational movement of the drive means95into a linear movement and to guide the movable plate94in a stable manner.

FIG.5shows the example of a hot beverage maker1designed as a stand-alone device with all relevant components for the preparation of a hot beverage. The beverage maker1comprises, inter alia, a housing11in which the storage container71for coffee beans B with a grinder70mounted underneath with a motor, the water tank14and the possibility of accommodating the flow conducting system2. The housing11also serves as a support frame for the brewing unit40, wherein an inclination of the brewing chamber41results in the inserted position. In its front region, the hot beverage maker1has a height-adjustable outlet20in which multiple extraction elements, here outlet nozzles21,22, are accommodated. In the present case, the extraction element22is a steam nozzle for dispensing hot steam or hot water, for example for diluting a finished coffee or for preparing a tea beverage. The extraction element21constitutes a dispensing line or dispensing nozzle21for dispensing coffee beverages. A brewing unit40with a brewing chamber41in the interior of the device1serves to prepare the beverage, wherein the coffee powder is introduced into the brewing chamber41and is subsequently flooded with hot water so that the finished coffee beverage is dispensed to the discharge line and through the dispensing nozzle21. The upper end-plate of the storage surface33is formed by a drip tray32which is provided with openings and slits for discharging liquid residues into a drip pan34present below the drip tray32. Furthermore, the hot beverage maker1comprises a coffee grounds container35, into which the used coffee grounds, for example coffee pucks, are discharged once the beverage has been prepared. The device1further comprises a control device18, which is configured to control the individual functional assemblies, such as pumps8, valve arrangement V and heating device9(designed as an instantaneous water heater) and grinder70, if present, as is necessary for the preparation of the respectively selected beverage. In this embodiment, the control device18, which is designed as a microcontroller uC with an associated memory MEM, is moreover configured to control the valves V of the flow conducting system2such that the hot water is pumped through the brewing chamber41. An operating and display device15arranged on the front panel10provides the means for user inputs and a display for state displays or input options for preparing beverages. The operating and display device15is preferably designed as a touch screen. The control tasks for the heating device8can be implemented or integrated in the control device18beverage maker1.

FIG.6schematically illustrates a washing machine80as an example of a water-conducting device. The washing machine80contains a housing81in which all essential components for the performance of an automated washing process are necessary. Here, it is the suds container82, the drum84rotatably driven therein, and the control device18. Furthermore, there is also a water connection83for connection to the supply network and a controllable inlet valve85in order to introduce water W into the suds container82and the drum84. The drainage device86below the suds container82serves to connect a circulation pump87in order to convey the water W or the suds admixed with washing agent out of the suds container82through the circulation line88into the upper region of the drum84and to inject it there. The heating device9is arranged on the pressure side of the pump87, which heating device9is designed as an instantaneous water heater, wherein the circulation line88is connected at the outlet92(FIGS.1to4) of the heating device9. Furthermore, the drainage hose89is closed off at the drainage device86in order to convey the used up suds or water W out of the suds container82by means of the drainage pump87a.

The control device18serves to activate and deactivate the pump87, the drive for the drum94, the heating device9and the valves85in order to carry out the desired washing process for the laundry800. The control tasks for the heating device9can be implemented or integrated in the control device18of the washing machine80.