Water hardness measuring device for a washing machine

Abstract

Water hardness measuring device for a washing appliance (1), such as a washing machine or a dishwasher, comprising at least one measuring tank container (4) arranged in a washing interior (2) of the washing appliance (1), which is filled with a first predeterminable volume of measuring tank process water (3), and at least one optically measuring transmission sensor device (10) for measuring an optical transmission and thus a degree of water hardness of a liquid mixture consisting of the measuring tank process water (3) and a successively supplied reagent liquid (8) within the measuring tank container (4) as a function of a quantity and a solution concentration of the supplied reagent liquid (8), characterized in that the measuring tank container (4) has a closure element (5) on its underside, which can close and open the measuring tank container (4) and is filled with process water from the washing interior (2).

Description

[0001] The invention relates to a water hardness measuring device for a washing device, such as a washing machine or a dishwasher, according to the preamble of patent claim 1.

[0002] Washing appliances, such as washing machines or dishwashers, often have the problem that the desired level of cleanliness of the laundry or dishes depends, among other things, on the amount of detergent or cleaning agent used. Therefore, one would normally strive to use a little too much detergent / cleaner rather than too little.

[0003] On the other hand, with increasing environmental pollution, there is a growing desire to use as little detergent / cleaning agent as possible in washing processes. In order to better adapt the amount of detergent / cleaning agent used per wash to the environment and the water used for washing / cleaning processes, it is necessary to know the water hardness of the water used in the respective environment. The higher the water hardness of the water used for the washing / cleaning process, the more detergent / cleaning agent is required for a washing / cleaning process to maintain a sufficiently clean condition of the laundry / dishes.

[0004] In addition, automated dosing systems are increasingly being used in washing machines and dishwashers to automatically allocate and dispense the desired amount of detergent / cleaning agent to the wash cycle. However, these automated dosing systems cannot currently determine and dispense the detergent / cleaning agent dosage based on the water hardness in the area where the washing machine / dishwasher is located.

[0005] Currently, it is not possible to directly measure the water hardness of the water used in washing machines and dishwashers. Currently available systems and machines use conductivity sensors to measure the water conductivity of the water used in order to draw conclusions about the water hardness. However, these measurement methods are not very accurate.

[0006] When determining water hardness using the water conductivity described above, there is also the disadvantage that if the domestic water or the water used in the machine comes from springs or wells near the sea, it may have a relatively high conductivity due to the salt content (sodium chloride), while exhibiting a low water hardness (calcium and magnesium ions). This leads to the washing machine / dishwasher actually detecting high water hardness based on the measurement and thus recommending a high consumption of detergent / detergent, but this is incorrect in this case.

[0007] Another possibility would be to locate the location of a washing machine / dishwasher and collect information about the water hardness in that geographical region. This can be done via an internet connection. If there is no internet connection, the washing machine / dishwasher can obtain and use information about the water hardness from stored maps. However, this data is not available everywhere and is not known for every location, and internet access cannot always be guaranteed.

[0008] Another problem with map-based data on water hardness is that the data becomes invalid as soon as the water supply changes, such as using a different source or well. This is known to happen by switching to different sources / wells several times a day.

[0009] Another option is for the end customer or the user of the washing machine / dishwasher to set the water hardness level or to enter it using a machine user interface or a smartphone app. For this, the user must first be familiar with the relevant information.

[0010] Manually entering the water hardness level depends on the user's willingness to enter the hardness level into the washing machine / dishwasher. Experience shows that few people are willing to do this. Furthermore, changing the water source during the day or over a longer period of time is also not taken into account.

[0011] It is therefore an object of the invention to provide a water hardness measuring device for a washing device which can reliably and automatically determine the water hardness of the water used within the washing device at any time and as often as required.

[0012] This object is achieved according to the features of patent claim 1.

[0013] According to the invention, a water hardness measuring device for a washing device, such as a washing machine or a dishwasher, comprises at least one measuring tank container arranged in a washing chamber of the washing device, which is filled with a first predeterminable volume of measuring tank process water, and at least one optically measuring transmission sensor device for measuring an optical transmission and thus a water hardness level of a liquid mixture consisting of the measuring tank process water and a reagent liquid within the measuring tank container as a function of a quantity and a solution concentration of the supplied reagent liquid. The reagent liquid is supplied successively.

[0014] By successively adding the reagent liquid with a known solution concentration and in predetermined dosages or volume quantities, it is achieved that a reaction caused by the reagent liquid within the measuring tank process water can be observed simultaneously, i.e. with increasing amount of reagent liquid in the measuring tank container with the measuring tank process water, sooner or later a desired reaction takes place in the form of a color change of the measuring tank process water depending on the elements within the process water that are decisive for the water hardness.Thus, a color change in the measuring tank wastewater, which is part of the total wastewater of the washing machine or dishwasher, is obtained when the reagent liquid is added successively and represents a sufficient amount within the resulting liquid mixture to trigger this reaction. For example, calcium and magnesium ions within the measuring tank wastewater could react with the reagent liquid through such a reaction.

[0015] Such a reaction, which determines a specific amount of elements or substances within the process water or used water, is then automatically measured optically using the transmission sensor device. This transmission sensor device measures a color change within the measuring tank and thus within the process water in the measuring tank. The transmission sensor device consists of an emitter in the form of an LED, such as a red LED, and a receiver in the form of a phototransistor or photodiode. The process water can be located between these two components.

[0016] There are various methods for inducing such a reaction and thus a change within the process water using reagent liquids to determine certain properties, such as the water hardness within the process water. However, in this case, a titrimetric water hardness measurement method and an associated measuring device are preferred, as these can be easily and inexpensively installed in a washing machine / dishwasher in addition to automated dosing systems for detergents / cleaning agents. In this titrimetric method, the reagent solution with a known solution concentration is added successively, i.e., in portions, and sequentially to the process water as the solution to be analyzed until a complete reaction between the reagent solution and the solution to be analyzed has occurred.This reaction in the form of a color change is clearly recognizable as the end point of the reaction, because the amount of the substance sought and, in this case, the amount of ions in the water responsible for the water hardness and thus the degree of water hardness can be calculated from the solution concentration of the reagent solution or reagent liquid and the total volume of the added reagent solution or reagent liquid required to reach the theoretical end point of the reaction.

[0017] A feed pump device is provided for the metered, sequential supply of a plurality of metered reagent liquid quantities with second predeterminable volumes into the measuring tank container. This feed pump device has the task of pumping a second predeterminable volume into the measuring tank process water in batches, each with a single pump stroke. Each quantity from the plurality of metered reagent liquid quantities is thus assigned to a pump stroke.

[0018] The feed pump device is connected on the inlet side to a storage tank for storing the reagent liquid with a predeterminable solution concentration.

[0019] During the continuous or intermittent measurement of the transmission or transmittance of the liquid mixture within the measuring tank, and thus of the process water within this tank, using the transmission sensor device, the reagent solution is continuously and successively fed into the measuring tank by the metering feed pump device. The predeterminable second volume of the reagent solution fed per pump stroke is known.

[0020] After a certain number of pump strokes, it can then be determined that the color of the process water or the water used within the measuring tank container changes, for example, from red to green. This is detected by an optical sensor of the transmission sensor device. The number of dosing pump strokes performed up to this point in time is then determined, and from this, the water hardness of the process water is determined using a calculation device. For this purpose, the calculation device for calculating the water hardness of the measuring tank process water in the liquid mixture can advantageously reliably determine the water hardness from the first volume, the second volumes, the solution concentration of the reagent liquid, and the number of pump strokes at the time of a color change in the liquid mixture measured by the transmission sensor device.Advantageously, the reaction of the reagent liquid with the process water to bring about the color change is based on a titrimetric method.

[0021] A method for measuring the hardness of water within a washing device, such as a washing machine or dishwasher, uses the following steps: - filling at least one measuring tank container arranged in a washing chamber of the washing device with measuring tank process water with a first predeterminable volume; - Dosed, sequential addition of a plurality of dosable reagent liquid quantities with second predeterminable volume quantities of the reagent liquid with predeterminable solution concentration into the measuring tank container by means of a feed pump device, and - simultaneous measurement of an optical transmission and thus a water hardness of a liquid mixture consisting of the measuring tank process water and the reagent liquid within the measuring tank container by means of at least one optically measuring transmission sensor device.

[0022] In addition, each quantity from the plurality of dosed reagent liquid quantities is assigned to a respective pump stroke of the feed pump device and the number of pump strokes is measured up to a point in time of a color change in the liquid mixture measured by the transmission sensor device as a function of the quantity of reagent liquid supplied.

[0023] In a preferred embodiment, the number of pump strokes is assigned to a water hardness level of the measuring tank's process water using a calculation device. This occurs with a known solution concentration and a known second volume of the reaction liquid.

[0024] It is advantageous to empty and clean the measuring tank after the water hardness measurement has been completed. This is done through a separate water outlet.

[0025] Further advantageous embodiments emerge from the subclaims in conjunction with the drawing

[0026] They show: Fig. 1 shows a schematic representation of the basic principle of a water hardness measuring device for a washing device according to the present invention; Fig. 2 shows in a graph the dependence of the pump strokes on the water hardness as calculated by the calculation device of the present invention.

[0027] In Fig. Figure 1 shows a schematic representation of a water hardness measuring device according to the invention for a washing device. This device is intended for a washing device, such as a washing machine or a dishwasher, as indicated by reference numeral 1. This washing machine 1 contains, in its interior washing chamber 2, water to be used, or service water 3, which is intended for the washing process. The housing of the washing machine 1 is only partially shown.

[0028] Within this housing of the washing machine 1, a measuring tank container 4 with an at least partially optically transparent housing is arranged, which has a closure element on its underside, such as a sliding element 5, which can close and open the measuring tank container 4, for example by linear movement according to reference numeral 14. Alternatively, any other type of closure element can be used, such as a type of lid with a folding hinge or with a rotating hinge in order to open the closure element by means of a folding movement or a rotating movement.

[0029] Initially, the closure element 5 is closed and the measuring tank container 4 is then filled with process water 3 or water to be used from the working area or the washing interior 2 of the washing machine.

[0030] A continuous or sequential optical transmission measurement is then performed using a transmission sensor device 10 located within the measuring tank container 4. The purpose of this transmission measurement is to detect a color change in the process water 3 within the measuring tank container 4 due to a changing transmission. At the same time, a reagent liquid 8 is metered from a storage container 9 via a feed pump device 7 (not shown in detail) and fed successively in steps. For this purpose, the feed pump device uses individual pump strokes, with each pump stroke delivering a second, predeterminable volume of reagent liquid with a predeterminable solution concentration.This second predeterminable volume quantity is determined during the supply, so that with each pump stroke a defined second volume quantity of reagent liquid 8 is supplied to the process water 3 within the measuring tank container 4.

[0031] Reagent liquid 8 may be EDTA with color-changing agents.

[0032] After a certain number of pump strokes, it is determined that the water or process water 3 within the measuring tank container 4 changes color, for example, from red to green. This is measured by the transmission sensor device 10. For this purpose, this device has an LED 11, the emitted light waves of which are received by a receiver in the form of a phototransistor 12. For this purpose, the process water 3 is measured for its color change between the emitter and the receiver in the area designated by reference numeral 13. Of course, this is a liquid mixture of the process water 3 and the reagent liquid 8, but the water hardness of the process water 3 is determined by the measurement taking place.

[0033] By counting the number of pump strokes until a color change occurs, for example, due to the application of a titrimetric method in area 13 of the measuring tank process water 3, it is determined how many pump strokes have been used or applied up to that point. Since the second volume of reagent liquid 8 introduced per pump stroke is known, the water hardness of the measuring tank process water 3 can be determined using the calculation device. In addition, the first volume of the measuring tank process water 3 is known, which can be used for the calculation. Furthermore, the solution concentration of the reagent liquid 8 must be known.

[0034] With reference to Fig. 2, which was created according to the invention from numerous tests and calculations of the water hardness using the device and the associated method described above, the water hardness is quickly determined using the graph shown therein.

[0035] In Fig. 2, the number of pump strokes 21 is plotted on the abscissa in a graph 20. The total hardness 22 is plotted on the coordinate. This graph clearly shows that, according to the linear curve 23, there is a direct relationship between the number of pump strokes 21 and the determined water hardness 22 when using the method and device according to the invention. Thus, the water hardness 22 can be determined quickly.

[0036] After the water hardness level has been determined, the closure element 5, which can be opened, for example, by linear movement, is opened again and the measuring tank container 4 is emptied and cleaned by means of the water outlet 6 in the direction of the arrow 15 in order to carry out a new filling to determine the water hardness level 22 again. List of reference symbols 1 washing device 2 washroom interior 3 measuring tank - domestic water 4 measuring tank containers 5 locking element 6 Water outlet 7 Feed pump device 8 Reagent liquid 9 storage tank containers 10 Transmission sensor device 11 LED 12 phototransistor 13 Area 14 Area 15 Arrow 20 graphs 21 pump strokes 22 water hardness 23 linear curve

Claims

[1] Water hardness measuring device for a washing device (1), such as a washing machine or a dishwasher, with at least one measuring tank container (4) arranged in a washing interior (2) of the washing device (1), which is filled with a first predeterminable volume of measuring tank process water (3), and at least one optically measuring transmission sensor device (10) for measuring an optical transmission and thus a water hardness level of a liquid mixture (3) consisting of the measuring tank process water (3) and a successively supplied reagent liquid (8) within the measuring tank container (4) as a function of a quantity and a solution concentration of the supplied reagent liquid (8). [2] Device according to claim 1, characterized bya feed pump device (7) for the metered, sequential feeding of a plurality of meterable reagent liquid quantities with second predeterminable volume quantities into the measuring tank container (4). [3] Device according to claim 2, characterized by that each quantity of the plurality of dosed reagent liquid quantities is assigned to a pump stroke (21). [4] Device according to claim 2 or 3, characterized by that the feed pump device (7) is connected on the inlet side to a storage tank (9) for storing the reagent liquid (8) with a predeterminable solution concentration. [5] Device according to claim 3 or 4 characterized bya calculation device for calculating the water hardness of the measuring tank process water (3) in the liquid mixture from the first volume quantity, the second volume quantities, the solution concentration of the reagent liquid (8) and the number of pump strokes (21) at the time of a color change in the liquid mixture (3) measured with the transmission sensor device (10). [6] Method for measuring a water hardness of water within a washing device (1), such as a washing machine or a dishwasher, characterized by following steps: - filling at least one measuring tank container (4) arranged in a washing interior (2) of the washing device (1) with measuring tank service water (3) with a first predeterminable volume quantity; - Dosed, sequential addition of a plurality of dosable reagent liquid quantities with second predeterminable volume quantities of the reagent liquid (8) with a predeterminable solution concentration into the measuring tank container (4) by means of a feed pump device (7) and, simultaneously with the previous step, measuring an optical transmission and determining a water hardness of a liquid mixture consisting of the measuring tank process water (3) and the reagent liquid (8) within the measuring tank container (4) by means of at least one optically measuring transmission sensor device (10). [7] Method according to claim 6, characterized by following steps: - Assigning each quantity from the plurality of dosed reagent liquid quantities to a respective pump stroke (21) of the feed pump device (7) - Measuring the number of pump strokes (21) up to a point in time at which a color change in the liquid mixture (3) measured by the transmission sensor device (10) occurs as a function of the amount of reagent liquid (8) supplied. [8] Method according to claim 6 or 7, characterized by that the number of pump strokes (21) is assigned to a water hardness level of the measuring tank process water (3) by means of a calculation device when the solution concentration and the second volume quantities of the reaction liquid are known. [9] Method according to one of claims 6-8, characterized by that the measuring tank (4) is emptied and cleaned after the water hardness measurement has been carried out.

Images