Improvements to the water softening system in a washing machine

Abstract: It is described an improved water softening system in a washing machine, particularly a dishwasher for domestic use, comprising a vessel (1) for ions exchange resins which have to be periodically regenerated, by passing a sodium chloride solution through them; the main feature of the described system is that there are provided means for varying the sodium chloride concentration of a fixed volume of water, to be used for the regeneration, by changing the path of the water inside the salt vessel (3).

Description: The present invention relates to an improved water softening system in a washing machine, particularly a dishwasher for domestic use, comprising a vessel of ion exchange resins which have to be periodically regenerated by passing a sodium chloride solution through them. Softening systems of this type are known; in fact they are used in almost all the dishwashers for domestic use. In these systems water for the washing supplied from the mains is passed through a resins vessel in order to minimize percentage of calcium which could hinder the activity of the detergents and leave dull deposits at the end of washing. As the resins became exhausted after a certain volume of water has been softened, they have to be regenerated by passing a sodium chloride solution through them; in this way the resins' calcium ions are replaced by the sodium ions and the resins are so ready for a new water softening phase. The water and salt (brine) volume which passes in contact with the resins is equivalent to the volume of water which, generally by gravity, is conveyed in the salt vessel, by a command of the timer to an electric valve arranged in the circuit; the possibility is usually provided to regulate the resin decalcification in function of the hardness of the mains water, by acting on a fixed regulation which causes a volume variation of the water which falls and, consequently, a bigger or smaller inflow of brine into the resins (decalcification with variable regeneration volume). This system has the drawback that the resins are not always wetted by the same volume of brine, so that not always are all the resins treated by the brine, and the optimal resins regeneration is not achieved. The features of the precharacterising portion of claim 1 are known from EP-A-0 219 704 which discloses a water softening system comprising a water softener, a salt container having an inlet, adapted to be supplied with a metered quantity of water, and an outlet connected to said water softener, and adjustable means for selecting the flow path of said metered quantity of water from the inlet to the outlet of said salt container. The solution as disclosed in the cited EP-A-0 219 704 presents some operating drawbacks, namely when the salt in the salt container is at a minimum level. Object of the present invention is to provide a softening system wherein the resins regeneration regulation is not subject to the cited drawback of the above cited system. To obtain said object, the subject of the present invention is a water softening system in a washing machine, particularly a dishwasher for domestic use, comprising: a vessel for ion exchange resins which have to be periodically regenerated by passing a sodium chloride solution through them, a salt container for sodium chloride having an inlet, adapted to be supplied with a fixed volume of water, and an outlet connected to said vessel for ion exchange resins, means operable for changing the path of said water within said salt container for varying the sodium chloride concentration of said fixed volume of water to be used for the regeneration of said ion exchange resins, characterised in that said means allow the selection of the desired path or paths among a plurality of possible paths of different lengths, all located in the bottom of the salt container. Further objects and advantages of the present invention will be clear from the detailed description which follows and from the attached drawings, which are supplied only as an explanatory and not limiting example, wherein: figure 1 shows schematically a horizontal cross-section of the container where the brine is prepared in a system according to the invention, in a first operating condition; figure 2 shows schematically a horizontal cross-section of the same container of figure 1, in a second operating condition; figure 3 shows schematically in vertical cross-section the same container of figure 1. With reference to figure 1, where there is schematically shown a horizontal cross-section of the container wherein the brine is prepared in a system according to the invention, in a first operating condition, reference number 1 indicates the resins vessel; reference number 2 indicates the pipe connector through which the water exits from the vessel 1; reference number 3 indicates the salt (sodium chloride) container for the brine preparation; reference number 4 indicates the pipe connector through which the regeneration water is let in the container 3; reference number 5 indicates the inlet connector of the water from the mains, to be softened, which is let in the vessel 1. With reference numbers 6 and 7 there are indicated two alternative exits for the regeneration water coming from pipe 4; channel 6 has several exit holes 8a, 8b, 8c; channel 7 has other exit holes 9a, 9b, 9c. A deviation device 10, commanded by a rotating device 12, provides for deviating the regeneration water towards channel 6 (see direction-arrow 11 of fig. 1); in this way the water exits in the container 3 through the range of holes 8. The brine then arrives at the resins vessel 1, through the channel 14 when the electric valve 13 is open. As the holes 8 are relatively far away from the inlet of channel 14, the regeneration water follows a quite long path through the brine, before arriving at the channel 14; the brine which passes in the resins vessel is consequently quite concentrated, and therefore able to perform a regeneration in the case of resins which have treated water which was very hard. In figure 2, where there is schematically shown a horizontal cross-section of the same container of figure 1, in a second operating condition, there are represented the same elements, indicated with the same reference numbers. The device 12, however, has been rotated through 90°, so that the deviation device 10 now provides for deviating the regeneration water towards channel 7; the water consequently exits through the range of holes 9, which are relatively close to the inlet of channel 14, and follows a quite short path through the brine, before arriving at the channel 14; the resulting brine is consequently not very concentrated, and therefore able to perform a regeneration in case of resins which have treated water whose hardness level was not very high. In figure 3 there is schematically shown a vertical cross-section of the same container of figure 1; reference numbers 3, 4 and 12 indicates the same elements described with reference to figure 1. With reference number 15 there is indicated a plastic spoon, furnished with the machine for detergent dosage purposes, which can be advantageously used also for executing the rotation of the command device 12, in order to choose the most suitable position in function of the hardness of the available water. In fact the handle of the spoon 15 is so constructed that it can be inserted in an appropriate notch located in the rod of the command device 12. The characteristics of the described softening system are clear from the given description and the annexed drawings. From the description the advantages of the softening system that is the object of the present invention are also clear. Particularly, they are represented by the fact that: by using an always constant volume of water, equivalent to the optimum one, there is obtained a full wetting of the resins in every regulating condition; the path followed by the regeneration water in the salt always occurs at the bottom of the container 3, so to exploit the greater possible concentration of the brine, which is always arranged in a stratified manner with maximum density in the lower zone; furthermore, the result is constant, whatever the quantity of salt remaining in the vessel, because the drawing is always done from the bottom; the regulation can be done very easily by the user, every time that there is this necessity. It is clear that many variations to the softening system, described as an example, are possible for the man skilled in the art. For instance it is possible to provide more than two regulating positions, providing three or more exit channels for the regeneration water in the container 3, arranged at different distances from the inlet of the channel 14; providing a regulating system with three or more positions it is also easily possible to obtain a regulation of a gradual type, for example by selecting (in the case of three paths) firstly only the shorter path, then only the medium one, then the short and the medium ones together, then only the longer one, then the medium and the longer ones together.

Claims: Water softening system in a washing machine, particularly a dishwasher for domestic use, comprising: a vessel (1) for ion exchange resins which have to be periodically regenerated by passing a sodium chloride solution through them; a salt container (3) for sodium chloride having an inlet (4), adapted to be supplied with a fixed volume of water, and an outlet (14) connected to said vessel (1) for ion exchange resins; means (6-10,12) operable for changing the path of said water within said salt container (3) in order to vary the sodium chloride concentration of said fixed volume of water to be used for the regeneration of said ion exchange resins, characterised in that said means (6-10,12) allow the selection of the desired path or paths among a plurality of possible paths of different lengths (6,8a,8b,8c;7,9a,9b,9c) being located in the lower most zone of the salt container (3). Water softening system according to claim 1, characterised in that said means (6-10,12) for changing the path of the water within the salt container (3) are provided for directing the water which enters the salt container (3) at least to a first zone (9a,9b,9c) being nearer to said outlet (14) and to a second zone (8a,8b,8c) being further from said outlet (14). Water softening system according to claim 1 or 2, characterised in that said means (6-10,12) for changing the path of the water within said salt container (3) comprise a deviation device (10,12) for the selection of the desired path or paths, said deviation device (10,12) being in particular operable to direct the water coming from said inlet (4) either towards said first zone (9a,9b,9c) or said second zone (8a,8b,8c). Water softening system according to at least one of the previous claims, characterised in that said means (6-10,12) for changing the path of the water within the salt container (3) comprise at least a constraining channel (6,7) which is defined in the bottom of the salt container (3) and presents one or more holes (8a,8b,8c;9a,9b,9c), said constraining channel (6,7) being in particular provided so as to convey the water coming from said inlet (4) to a predetermined zone in the inside of the salt container (3). Water softening system according to claims 3 and 4, characterised in that the deviation device (10,12) is operable for directing the incoming water either to a first (7) or a second constraining channel (6), the water entering the salt container (3) through the holes (8a,8b,8c;9a,9b,9c) of the channel (6,7) selected by means of the deviation device (10,12). Water softening system according to at least one of the previous claims, characterised in that the deviation device (10,12) is arranged in the bottom of the salt container (3). Water softening system according to claims 5, characterised in that the deviation device (10,12) is interposed between the constraining channels (6,7) so as to be shielded from possible jamming by the salt contained in the salt container (3). Water softening system according to one or more of the previous claims, characterised in that said means (6-10,12) for changing the path of the water within said salt container (3) comprise more than two channels which have different lengths and can be selected through the deviation device (10,12). Water softening system according to one or more of the previous claims, characterised in that the deviation device (10,12) is of the rotating type. Water softening system according to the previous claim, characterised in that a rod shaped element (15,12) is provided vertically in the salt container (3), for allowing the operation of the rotating deviation device from the top of the salt container (3).

Inventors: BONGINI DINO, BONGINI, DINO
Applicants: MERLONI ELETTRODOMESTICI SPA, MERLONI ELETTRODOMESTICI S.P.A.
Application year: 1990
Main classification: A47L15
IPC codes: A47L15