Control device for loading differentiated volumes of washing liquid in a dishwashing machine

Abstract: A device for controlling the loading of washing liquid in a dishwashing machine comprises a first tank (8) arranged as an offtake to the supply of liquid by a solenoid valve (4) for supplying a washing tank (1) of the dishwashing machine so as to receive a smaller first fraction of liquid, connecting means (15, 50) that keep the first tank (8) in communication with the tank (1) during the loading of the washing liquid so that the level of the liquid in the first tank (8) coincides with the level of the liquid in the washing tank (1), level detection means (9, 10, 13) associated with the first tank (8) to perform the closing of the supplying solenoid valve (4) when the level of the liquid in the first tank (8) and in the washing tank (1) exceeds a first predetermined level (L1), a second tank (16) also arranged as an offtake to the supply of liquid by the supplying solenoid valve (4) so as to receive a smaller second fraction of said liquid, and a syphon-like conduit (19) associated with said second tank (16) that is triggered when the level of the liquid in the second tank (16) reaches a second prescribed level (L2) so as to transfer the liquid present in the second tank (16) completely into the first tank (8) so as to determine the intervention of said level detection means (9, 10, 13). The second tank (16) is provided with a first baffle (20, 21) suitable for circumscribing a portion of tank (A, C). Air venting means (22, 23) are associated with said portion of tank (A, C) that can be opened or closed to allow or to prevent, when open or when closed, respectively, the liquid from filling said portion of tank (A, C), so that said second prescribed level (L2) is reached when a first or a second volume of liquid, respectively, is present in the second tank (16), the first volume of liquid being larger than the second volume of liquid.

Description: The present invention relates to a control device for loading differentiated volumes of washing liquid in a dishwashing machine. In the Italian patent application No. MI94A002144 filed on 20 October 1994 in the name of the same applicant a control device for loading differentiated volumes of washing liquid in a dishwashing machine is described that performs a double check of the volume of water loaded into the washing tank of the dishwashing machine, that is a check of the volumetric type on a flow of liquid proportional to the main flow of liquid that supplies the tank directly, and a check of the level of liquid present in the washing tank. The abovementioned control device comprises a single block wherein there are obtained: a first tank supplied by a flow of Liquid partialized by means of a nozzle with respect to the main flow that supplies the tank directly; a pressostatic chamber associated with the first tank that, when the level of the liquid in the first tank exceeds a given level (coincident with the level of liquid that it is desired to have in the tank) is filled by the liquid that overflows from the first tank to determine the activation of a pressure switch, which interrupts the introduction of liquid; a second tank also supplied by a flow of liquid partialized with respect to said main flow; a first and a second syphon-like conduit associated with said second tank both running into the first tank. The bottom of the first tank is connected to the bottom of the washing tank by means of a one-way valve that allows the passage of the liquid from the first tank to the washing tank, but not vice versa. While the washing liquid is being loaded, the liquid that is supplied as an offtake from the main flow to the first tank flows into the washing tank, keeping the one-way valve open, so that the washing tank and the first tank form two communicating vessels: the level of the liquid in the washing tank is thus always coincident with the level of the liquid in the first tank, so that when the level of the liquid in the tank reaches the desired value, the liquid in the first tank overflows into the pressostatic chamber determining the activation of the pressure switch. The first tank thus constitutes a system for controlling the level. The second tank and the two syphon-like conduits, on the other hand, constitute a system of volumetric control, of the type described for example in the Italian patent application No. MI94A000353 again in the name of the same applicant, that allows the introduction of liquid into the tank to be cut off when a given quantity of liquid has been loaded into the second tank. The first syphon-like conduit is automatically triggered when the level of the liquid in the second tank reaches a first level, and once it is triggered it transfers all the liquid present in the second tank into the first tank, determining the overflow of the liquid in the first tank into the pressostatic chamber and the intervention of the pressure switch. The second syphon-like conduit has a triggering level that is higher than the triggering level of the first syphon-like conduit. With the first syphon-like conduit there is also associated a solenoic valve that is kept closed (so as to prevent the triggering of the first syphon-like conduit) when it is desired that the second syphon-like conduit trigger, while it is kept open when when it is desired that the first syphon-like conduit trigger. In this way it is possible to execute differentiated loadings of volumes of liquid. The described device is somewhat complex, as it requires the presence of two syphon-like conduits with differentiated triggering levels. In view of the described state of the art, the object of the present invention is to provide a control device that has the same functional features of the device according to the state of the art described above, but that has a simpler structure. According to the present invention, such an object is attained thanks to a device for controlling the loading of washing liquid in a dishwashing machine, comprising a first tank arranged in such a way as to take off the supply of liquid by a solenoid valve for supplying a washing tank of the dishwashing machine so as to receive a smaller first fraction of said liquid, connecting means that keep said first tank in communication with said washing tank during the loading of the washing liquid so that the level of the liquid in the first tank coincides with the level of the liquid in the washing tank, level detection means associated with said first tank to perform the closing of the supplying solenoid valve when the level of the liquid in the first tank and in the washing tank exceeds a first predetermined level, a second tank being arranged as an take off tank for the supply of liquid by the supplying solenoid valve so as to receive a smaller second fraction of said liquid, and a syphon-like conduit associated with said second tank that is triggered when the level of the liquid in the second tank reaches a second prescribed level so as to transfer the liquid present in the second tank completely into the first tank so as to determine the intervention of said level detection means, characterized in that said second tank is provided with a first baffle suitable for circumscribing a portion of tank, and in that it comprises air venting means associated with said portion of tank that can be opened or closed to allow or to prevent, when open or when closed, respectively, the liquid from filling said portion of tank, so that said second prescribed level is reached when a first or a second volume of liquid, respectively, is present in the second tank, said first volume of liquid being larger than said second volume of liquid. The control device according to the present invention allows a check both of the volumetric type and of the level of the volume of liquid loaded into the washing tank of the dishwashing machine, also allowing the loading into the tank of differentiated volumes of liquid without, on the other hand, requiring, as in the case of the device according to the known art, the presence of two syphon-like conduits with differentiated triggering levels. The control device according to the invention thus has a simpler structure. These and other features of the present invention will be made more evident by the reading of the following detailed description of an embodiment thereof, illustrated as a non-limiting example in the enclosed drawings, wherein: Fig. 1 is a cross-sectional diagrammatic view taken along a vertical plane of a dishwashing machine provided with a control device according to the present invention, in a first operative condition; Fig. 2 is similar to Fig. 1, but it refers to a second operative condition of the control device; Fig. 3 is similar to Figs. 1 and 2, but it shows a third operative condition of the control device. With reference to Fig. 1, there is shown, partially in cross-section along a vertical plane, a washing tank 1 of a dishwashing machine. On the bottom of the tank 1 there is a sump 2, that communicates with the washing tank 1 through a filtering plate 3. To the sump 2 there are also connected a washing pump that supplies a pair of distribution rotors (not shown) inside the washing tank 1, and a discharge pump (also not shown) to discharge the liquid present in the tank 1. There is also shown diagrammatically in Fig. 1 a supplying solenoid valve 4 connected to a conduit for supplying clean water. At the outlet of the supplying solenoid valve 4, the water is sent, by means of a conduit 5, directly into the sump 2, from which the water flows into the washing tank 1. The water issuing from the supplying solenoid valve 4 is also sent, by means of a conduit 6 as an offtake to the conduit 5, to a device 7 for controlling the quantity of water loaded into the washing tank 1. The control device 7 is preferably made in the form of a single block comprising a first tank 8, a pressostatic chamber 9 associated with the first tank 8 and connected to a pressure switch 10, a first loading column 11 with a partializing nozzle 12 opposite the point where it connects with the conduit 6, said loading column 11 opening at its upper end into the first tank 8, a baffle 13 that separates the first tank 8 from the pressostatic chamber, so that the water present in the first tank 8 overflows into the pressostatic chamber 9 when it reaches a level L1 (that, as will be seen later, coincides with the level of water that it is desired to have in the tank 1), a syphon 14 that places the bottom of the pressostatic chamber 9 in communication with the bottom of the first tank 8. To the bottom of the first tank 8 there is connected a conduit 15 that communicates, through a one-way valve 50 in the sump 2, with the washing tank 1. The control device 7 also comprises a second tank 16, or measuring tank, to which there is connected a second loading column 17 provided at its mouth with a partializing nozzle 18. A syphon-like conduit 19 has a mouth placed opposite the bottom of the tank 16, it extends almost to the top of the tank 16, it bends like an elbow and descends again until it reaches the upper part of the first tank 8. From an upper wall 51 of the second tank 16 there extend vertically downward a first baffle 20 and a second baffle 21; the baffle 20 defines with the walls of the tank 16 a portion of tank A; the baffle 21 extends downward for a part that is greater than the baffle 20. In the upper wall 51 of the tank 16, in a part included between the baffle 21 and the syphon-like conduit 19, there is an aperture 52 for venting the air. At the top of the tank 16, in a vertical wall of the latter's that, together with the baffle 20, defines the portion A of the tank 16, there is an aperture 22; a solenoid valve, mounted outside the control device 7, controls the opening or the closing of said aperture 22. As is visible in Fig. 1, a conduit 90 places the sump 2 in communication with a column 91 obtained in the tank 8; between the loading column 11 and the loading column 17 there is also obtained a safety column 70, with a height equal to that of the column 91, connected to a safety block pressostatic device (not shown) that equips the supplying solenoid valve 4. The control device 7 operates in the following manner. When during a washing cycle a step is reached wherein water is to be loaded, a programming unit or timer (not shown) that governs the dishwashing machine determines the opening of the supplying solenoid valve 4; water is sent directly to the sump 2, and then to the washing tank 1, through the conduit 5. A fraction of the water is, however, sent, through the conduit 6, the partializing nozzle 12 and the loading column 11, to the first tank 8, from which the water then flows, through the conduit 15 and the one-way valve 50, to the sump 2 and then to the tank 1; the one-way valve 50 is kept open by the flow of water from the first tank 8, and thus the tank 1 and the first tank 8 constitute communicating vessels: the level of the water in the washing tank 1 thus coincides with the level of the water in the first tank 8. When the level of the water in the tank 1 reaches the desired level L1, the water in the first tank 8 overflows into the pressostatic chamber 9 (because the baffle 13 that separates the pressostatic chamber 9 from the first tank 8 extends up to the height above ground corresponding to the level L1). The pressure of the air in the pressostatic chamber 9 determines the intervention of the pressure switch 10, that drives the closing of the supplying solenoid valve 4. The first tank 8, the pressostatic chamber 9 and the pressure switch 10 constitute a control system operating on the level of the water in the tank 1. As already described in the Italian patent application No. MI94A002144, this system can be influenced by the imperfect planarity of the dishwashing machine. In order to overcome this drawback, the device 7 also comprises a control system of the volumetric type, consisting of the second tank 16 and of the syphon-like conduit 19. Simultaneously with what has been described above, a fraction of water is also supplied, through the partializing nozzle 18 and the loading column 17, to the second tank 16. Supposing for a moment that the solenoid valve 23 is kept in the position wherein the aperture 22 is open, the water inside the tank 16 goes on to occupy the entire volume of the tank itself, except for a small portion of tank B defined by the baffle 20, by the baffle 21 and by the upper wall 51 of the tank 16. When the water in the tank 16 has reached a level L2 corresponding to the trigger of the syphon-like conduit 19, the latter is automatically triggered, and starts to transfer quickly the water present in the second tank 16 to the first tank 8, determining the sudden overflow of the latter into the pressostatic chamber 9 and thus the intervention of the pressure switch that drives the closing of the supplying solenoid valve 4. But if the solenoid valve 23 is in the position wherein the aperture 22 is closed, as shown in Fig. 2, the water inside the tank 16 cannot occupy a portion of the tank having a volume equal to the sum of the volumes of the portions A and B described earlier, and of the volume of a portion C included between the part of baffle 21 that extends beyond the baffle 20 and the side wall of the tank 16, due to the pressure of the air present in said portion of tank that finds no way of escape. The triggering level L2 of the syphon-like conduit 19 is thus reached when a sufficient quantity of water has been loaded into the tank 16 that is less than in the previous case. The triggering of the syphon-like conduit 19 determines the rapid transfer of the water present in the second tank 16 to the first tank 8, determining the rapid overflow of the latter into the pressostatic chamber 9 and thus the intervention of the pressure switch 10 that determines the closing of the supplying solenoid valve 4. Since the quantity of water that is loaded into the second tank 16 is a fraction of that which is loaded into the washing tank 11, in this second case where the aperture 22 is closed the supplying solenoid valve 4 is closed when a quantity of water has been loaded into the tank 1 that is less than in the previous case wherein the aperture 22 was open (for example, 3.5 l against the 4.5 l of the previous case), corresponding to a tank level L3. A controlled loading has thus been achieved of a partial volume of washing liquid, useful for example when a reduced load of dishes is to be washed. There is shown in Fig. 3 the case wherein a volume of liquid is to be loaded into the tank 1 that is intermediate between the maximum one (Fig. 1) and the reduced one (Fig. 2), corresponding to a level L4 in the tank. The tank 16 is provided on its upper wall 51, in an area between the baffles 20 and 21, with a venting appendix 55 that is normally closed, but that can be opened by hand (for example, by cutting off its upper end) so that when the solenoid valve 23 is in the position wherein the aperture 22 is closed, the only portion of the tank 16 that is not filled with water is the portion A, while portions B and C can be filled. In this way, the level L2 in the tank 16 (the level at which the syphon-like conduit 19 is triggered) is reached when a volume of water has been loaded into the tank 16 (and correspondingly into the tank 1) that is less than in the case of Fig. 1, but more than in the case of Fig. 2.

Claims: A device for controlling the loading of washing liquid in a dishwashing machine, comprising a first tank (8) arranged in such a way as to take off the supply of liquid by a solenoid valve (4) for supplying a washing tank (1) of the dishwashing machine so as to receive a smaller first fraction of said liquid, connecting means (15, 50) that keep said first tank (8) in communication with said washing tank (1) during the loading of the washing liquid so that the level of the liquid in the first tank (8) coincides with the level of the liquid in the washing tank (1), level detection means (9, 10, 13) associated with said first tank (8) to perform the closing of the supplying solenoid valve (4) when the level of the liquid in the first tank (8) and in the washing tank (1) exceeds a first predetermined level (L1), a second tank (16) being arranged as an take off tank for the supply of liquid by the supplying solenoid valve (4) so as to receive a smaller second fraction of said liquid, and a syphon-like conduit (19) associated with said second tank (16) that is triggered when the level of the liquid in the second tank (16) reaches a second prescribed level (L2) so as to transfer the liquid present in the second tank (16) completely into the first tank (8) so as to determine the intervention of said level detection means (9, 10, 13), characterized in that said second tank (16) is provided with a first baffle (20, 21) suitable for circumscribing a portion of said second tank (A, C), and in that it comprises air venting means (22, 23) associated with said portion of tank (A, C) that can be opened or closed to allow or to prevent, when open or when closed, respectively, the liquid from filling said portion of tank (A, C), so that said second prescribed level (L2) is reached when a first or a second volume of liquid, respectively, is present in the second tank (16), said first volume of liquid being larger than said second volume of liquid. A device according to claim 1, characterized in that said level detection means (9, 10, 13) comprise a pressostatic chamber (9) connected to a pressure switch (10) that intervenes when the pressure of the air in the pressostatic chamber (9) exceeds a pre-established value to determine the closing of said supplying solenoid valve (4), said pressostatic chamber (9) being separated from said first tank (8) by a second baffle (13) having a height equal to said first prescribed level (L1). A device according to claim 2, characterized in that said air venting means (22, 23) comprise a venting aperture (22) located substantially at the top of said portion of said second tank (A, C), and valve means (23) suitable for opening and closing said venting aperture (22). A device according to claim 3, characterized in that said valve means (23) comprise a solenoid valve. A device according to any of the claims 1-4, characterized in that said first baffle (20, 21) comprises a third baffle (20) and a fourth baffle (21), the third baffle (20) extending vertically from an upper wall (51) of the second tank (16) for a first part and circumscribing with a side wall of the second tank (16) a first portion of said second tank (A), and the fourth baffle (21) extending vertically from said upper wall (51) for a second part larger than said first part and circumscribing a second portion of said second tank (B), included between said third baffle (20) and fourth baffle (21), and a third portion of said second tank (C), below said first (A) and second (B) portions of said second tank. A device according to claim 5, characterized in that said air venting means (22, 23) are associated with said side wall of the second tank (16), substantially at the top of said first portion of said second tank (A). A device according to claim 6, characterized in that said air venting means (22, 23) prevent, when closed, that the liquid in the tank (16) fill said first (A), second (B) and third (C) portions of tank. A device according to claim 6, characterized in that at the top of said second portion of tank (B) there are second air venting means (55) that can be opened by hand to allow, when said air venting means (22, 23) are closed, the liquid in the second tank (16) to fill the second (B) and the third (C) portion of said second tank, so that said second pre-established level (L2) is reached when in the second tank (16) there is present a third volume of liquid, intermediate between said first volume and second volume.

Inventors: FUMAGALLI SILVANO, FUMAGALLI, SILVANO
Applicants: CANDY SPA, CANDY S.P.A.
Application year: 1996
Main classification: A47L15
IPC codes: A47L15