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(11) | EP 0 753 281 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A device for controlling the level of feed water of dishwasher machines and the like |
| (57) A device for the regulation of the volume of feed water in the washing drum (16)
of a dishwasher machine, having a chamber (104) for controlling the volume of water
for feeding the washing drum (16), a first drain syphon (114) communicating with said
control chamber (104) and having an overflow threshold (120) defining a threshold
of measurement of the feed water volume, a compression chamber (122) connected to
the first drain syphon (114) and to a second drain syphon (126), a chamber (134) for
generating a pressure signal connected to the compression chamber (122) by means of
which air is compressed in said pressure signal generation chamber (134) after the
water has passed the measurement threshold (120) of said first drain syphon (114),
said pressure signal generation chamber (134) sending a pressure signal to a pressure
sensing element (144) by means of which said pressure signal is converted into a command
signal suitable for blocking the feed of water to the washing drum (16) of the dishwasher;
said second drain syphon (126) being connected to the washing drum (16) of the dishwasher
wherein it drains the water from inside the control section (102). |
[0001] The present invention relates to a device for regulating the volume of water for feeding the washing drum of dishwasher machines and the like.
[0002] Dishwasher machines are normally provided with a washing drum for washing dishes containing a liquid or washing water whose volume is regulated by means of a level regulation device.
[0003] The traditional version of this regulation device consisted either of a float chamber or of an air trap or compression chamber which commanded a valve for controlling the feed of water for the drum of the dishwasher.
[0004] Said level control chambers of the traditional type were connected to vessels communicating with the washing drum with the disadvantage that the dirt present in the washing water could then encrust them or clog them, making them inoperative.
[0005] These traditional regulation systems were also extremely inaccurate in that by measuring the level directly in the drum, in the case of a measuring error of a few millimetres, which is within normal working tolerances, inaccurate feed water measurements were obtained.
[0006] To avoid this, the Applicant has provided a device for controlling the feed of water, described in the Italian patent application no. Ml92A002636 by the same Applicant, wherein a pneumatic chamber was provided for the generation of a pressure signal which served to command the interruption in the flow of water towards the washing drum. Said pressure chamber was connected by means of a syphon to a control chamber fed with water via a calibrated nozzle formed in the pipe for feeding mains water to the washing drum. At the end of the washing cycle, the water contained in the control chamber was drained by the suction provided by the drain pump of the washing drum which was connected, via a suitable pipe, to the outlet of said syphon for connection to the pneumatic chamber.
[0007] With the use of this device however, the trigger pressure was reached gradually, starting from zero pressure which gradually increased as the water entered the control chamber, via said small calibrated nozzle. Given this gradual pressure increase, at the trigger pressure there was uncertainty in actuation of the pressure sensing element, so that the water feed level in the drum was not accurately determined. Thus excessive water or else a lower quantity of water than that required for washing was used.
[0008] According to other known provisions, it was preferred to empty the control chamber directly by means of a solenoid valve connected to a hole formed on the base of the control chamber. Said solenoid valve was controlled by the control timer of the dishwasher.
[0009] The use of the drain pump or of a suitable solenoid valve for emptying or resetting the control chamber is disadvantageous both from the point of view of costs which the arrangement of a connection to the drain pump involves and in the adaptations whereto the structure of said pump has to be subjected in order to provide this additional function, as well as due to the cost inherent in the use of a solenoid valve and the relevant electrical connections to the timer of the dishwasher.
[0010] The fact that the hard mains water passes through the nozzle for filling the control chamber may in the long term entail, given its small size, clogging of the same caused by calcareous encrustations.
[0011] In the device described in the Italian patent application no. Ml92A002636 provision was also made, in the control chamber, for a float connected to a Reed switch which acted as a second safety level device. Said float and said switch occupy a relatively large volume which therefore requires said chamber to be configured with excessively large dimensions.
[0012] The object of the present invention is that of providing a device for regulating the volume of feed water of the washing drum of dishwasher machines and the like wherein the use of solenoid valves or connections to the drain pump of the washing drum of the dishwasher is avoided, in order to achieve emptying of the chamber for controlling the feed volume of the washing drum. The present invention substantially sets out to provide a regulation system whose resetting or restoring in view of a new feed cycle takes place fully automatically without requiring the use of pumps or solenoid valves.
[0013] Another object of the present invention is that of providing a system of regulation of the feed of water which is small in size and not bulky and suitable for integration with other elements to form a single, small block. Nowadays the need is felt to provide, integrated in a single plastic block, several accessory systems for dishwashers, such as the system for controlling the water feed, the system of condensation of the steam released by the washing drum, the system of regeneration of the decalcifcation resins and others. A small size of these individual systems or devices is therefore extremely desirable in view of their arrangement in a single integrated block.
[0014] A further object of the present invention is that of providing a system for the regulation of the feed of water to the washing drum of dishwasher machines wherein any risk of encrustation or clogging is avoided, and moreover which allows the water used for the control to be drained directly into the washing drum where only decalcified water has to be present.
[0015] The previous objects are achieved by providing a device for the control of the volume of water fed to the washing drum of a dishwasher machine and the like having, as disclosed in claim 1 attached hereto, a section for control of the water feed comprising a first chamber for control of the volume of water for feeding the washing drum wherein a quantity of water is fed proportional to the volume of water for feeding the washing drum, characterized in that it further comprises a first drain syphon having an inlet communicating with said control chamber at the base of the latter, an outlet and an overflow threshold defining a threshold of measurement of the feed water volume; an intermediate compression chamber connected to said outlet of the first drain syphon and to the inlet of a second drain syphon of the device; a pressure signal generation chamber communicating for an air compression with said intermediate compression chamber whereby air is trapped and compressed in said primary pressure signal generation chamber after the water has passed the measurement threshold of said first drain syphon, said pressure signal generation chamber providing a pressure signal to a pressure sensing element whereby said pressure signal is converted into a command signal suitable for blocking feeding of water to the washing drum of the dishwasher; said second drain syphon having also a respective outlet and a respective overflow and drain trigger threshold, said outlet of the second drain syphon directly communicating with the washing drum of the dishwasher in which it drains the water from inside the control section on passing of said drain threshold of the second drain syphon.
[0016] In this way a system is obtained for level regulation which is automatically reset without requiring the use of any electrical valve, pump or mechanical part of another type, as was however required for the systems of the prior art. For this reason a system of measurement and regulation of the level of feed water of dishwasher machines is obtained which is extremely simple, free from risks of malfunctioning linked to breakages of the pumps or solenoid valve and which also has a lower cost than similar devices of the prior art.
[0017] With the use of this regulation system, the pneumatic chamber for generation of the pressure signal is provided, thanks to the triggering of the first control syphon after the water has reached the first measurement threshold of the latter, with a sharp increase in the pressure of the air contained therein and hence reliable and prompt triggering of the sensing element at the increase of the pressure of the air in said chamber.
[0018] Said pressure sensing element is often formed by a pressure switch wherein the calibration of the trigger pressure is usually irksome and difficult to obtain. The sharp pressure increase in the pneumatic chamber means that an accurate calibration of the pressure switch is no longer required, with a further saving in working hours and costs.
[0019] The present invention will be made clearer on reading of the following description, relating to preferred embodiments of the invention, to be read with reference to the accompanying drawings, in which:
Figure 1 is a schematic perspective view of a dishwasher;
Figures 2 and 3 are sectioned views of a first preferred embodiment of the present invention, referring respectively to two different working conditions of the system;
Figures 4 to 11 are sectioned views of a second preferred embodiment of the present invention referring respectively to different working conditions of the system of the present invention;
Figure 12 is a sectioned view of a third preferred embodiment of the present invention.
[0020] Figure 1 shows, denoted by reference numeral 10, a dishwasher of the traditional type comprising at least one external framework 12 having a front door 14 for closing an aperture 15 through which the dishes are placed in the washing drum 16.
[0021] The device of the present invention, as shown in Figure 1, is situated in a block 18, together with other devices not shown and described, which is housed between the lateral wall of the washing drum 16 and the opposite wall of the covering shell or framework 12 of the dishwasher.
[0022] The feed water of the dishwasher is taken from the water supply system via a suitable tap 20 or the like.
[0023] As shown in the following Figures 2 and 3, the device 100 for the regulation of the volume of feed water of the washing drum 16 of dishwashers, the object of the present invention, has a primary section 102 for controlling the feed of water comprising a primary chamber 104 for controlling the volume of feed water of the washing drum wherein a quantity of water proportional to the volume of feed water of the washing drum is fed, via two nozzles 106 formed in the pipe 108 for feeding water to said washing drum 16.
[0024] Obviously for the present invention even a single tapping nozzle 106, provided it is adequately shaped, as also a larger number than the two shown, would be suitable for the purpose.
[0025] The arrows in the figures are intended to indicate the fluid which flows dynamically inside the system. In Figure 2, after a proportional portion of the fluid has been diverted towards the control section 104 at the sections of the tapping nozzles 106, the main flow of the fluid reaches the washing drum 16 via the outlet 110 and the pipe 112.
[0026] According to the present invention said regulation section 102 further comprises a first control syphon 114 having an inlet 116 communicating with said control chamber 104 at the base of the latter, an outlet 118 at a lower level than said inlet 116 and an overflow threshold 120 placed between said inlet and outlet 116, 118, defining the first threshold of measurement of the feed water volume.
[0027] The outlet 118 of the first syphon 114 is also connected via a pipe or intermediate chamber 122 to the inlet 124 of a second drain syphon 126. The second syphon 126 also has an outlet 128 at a level lower than said inlet 124 and a drain trigger and overflow threshold 130 placed between said inlet and outlet 124, 128.
[0028] In said intermediate connection chamber 122, arranged between said outlet 118 of the first syphon 114 and said inlet 124 of the second syphon 126, there is a feed mouth 132 of a pressure signal generation chamber 134 in which air is trapped and compressed, after the water, as will be made clearer hereinbelow, inside the control chamber 104 and the first syphon 114 has passed the measurement threshold level 120 of the first syphon.
[0029] The intermediate chamber 122 forms a compression chamber for the air trapped in the chamber 134.
[0030] Said pressure signal generation chamber 134 has a further aperture 138 which connects the chamber 134 via the opening 140 and the air pipe 142 to a pressure switch 144 connected in turn to the control parts of the dishwasher, such as for example the timer. This fact has not been expressly shown in the drawings.
[0031] Obviously, instead of said pressure switch 144, the air trapping chamber 134 could have been connected to any other means suitable for interrupting the flow of feed water towards the washing drum of the dishwasher, for example as described in the patent Ml92A002636, it could have been connected directly to a pneumatic valve suitable for blocking the feed of water at the tap for inflow from the mains 20.
[0032] When, inside said pneumatic chamber 134, the air pressure has reached a predetermined trigger value, the respective pressure signal reaches said pressure switch 144, which is triggered in order to convert said trigger pressure signal into an electric signal entering the control device of the dishwasher.
[0033] The outlet 128 of the second syphon directly communicates with the washing drum 16 of the dishwasher via a passage 145 in the block 18, which flows into an opening 146 and an external pipe 148.
[0034] Reference numeral 150 denotes in the figures a hole which opens towards the outside and with which the air is progressively expelled while the water rises inside the chamber 104.
[0035] As shown, said first and second syphons of the primary section for regulation of the feed water level are arranged one above the other, enclosing one with the other said air trapping chamber, so as to provide a particularly compact arrangement which occupies a small volume inside the block 18 wherein said regulation device is housed together with other devices for the dishwasher, such as for example the device for release of steam from the washing drum and the storage tank for the regeneration water.
[0036] The operation of the system is briefly as follows: as shown in Figure 2, during feeding of washing water to the drum 16 of the dishwasher machine, via the nozzles 106 a quantity of water proportional to the water which enters the washing drum 16 is poured into the control chamber 104. The water rises in the control chamber 104 and in the first section of the syphon 114 until it reaches the threshold 120 of the latter. This threshold 120 is naturally reached when the level required for washing is reached in the drum 16. As shown in Figure 3, as soon as the water passes said measurement threshold 120, the syphon 114 triggers and the water rapidly flows out of the control chamber 104 and rushes towards the intermediate compression chamber 122 so as to compress with force, making its pressure level rise sharply, the air trapped inside the chamber for compressed air 134, providing a pressure signal to the pressure switch 144 which reliably commands interruption of the feed of water to the drum of the dishwasher. The impulse with which the water descends from the control syphon 114 is sufficient for passing the threshold 130 of the second syphon 126, with a height considerably lower than that (120) of the first syphon 114. Said drain syphon 126 allows constant suction of water from the first syphon 114 and the two syphons 114, 126 remain triggered until the control chamber 104 is completely emptied and is thus ready to be filled again at a new feed cycle of the drum of the dishwasher.
[0037] It is not therefore necessary to use any electromechanical means for resetting the control system. Having reached and passed the measurement level the system is automatically emptied.
[0038] In the subsequent figures another preferred embodiment of the present invention is shown, wherein the regulation section described above cooperates with another secondary regulation section which triggers in the event of non-intervention by the pressure switch of the primary control section.
[0039] The primary control section of this second preferred embodiment is wholly similar to the one described above for the first preferred embodiment and will not therefore be described again here in detail.
[0040] In this second preferred embodiment, said first control section does not drain directly into the drum of the dishwasher but provides for the use of a solenoid valve 200 or any other part for shutting off the flow which can be adequately controlled to allow emptying of the feed water control system.
[0041] In the present case, the gate of said solenoid valve 200, normally closed, is opened to allow the water to flow to the washing drum 16 when, after the washing cycle, the drum 16 of the dishwasher has to be filled again, or the device for regulating the water fed into said washing drum 16 has to be emptied.
[0042] With special reference to Fig. 4, it can be seen that this second preferred embodiment of the device for regulation of the volume of feed water of the washing drum of dishwasher machines of the present invention comprises a secondary section 202 for regulation of the feed of water, having a second chamber 204 for controlling the volume of feed water of the washing drum wherein a quantity of water proportional to the volume of feed water of the washing drum is fed via two nozzles 206 formed in the pipe 108 for feeding water to said washing drum 16.
[0043] As shown, said nozzles 206 are arranged downstream of said nozzles 106 of the first control section 102. However according to a further embodiment said nozzles 206 could be arranged upstream of these nozzles 106 without thereby departing from the concept claimed here.
[0044] Here again, naturally, the use of a single tapping nozzle 206 is equally suitable for the purpose, provided it is adequately shaped, as also a number higher than the two shown.
[0045] According to the present invention, said secondary control section 202 further comprises, like the first, a respective third control syphon 214 having an inlet 216 communicating with said secondary control chamber 204 at the base of the latter, an outlet 218 at a level lower than said inlet 216 and an overflow threshold 220 placed between said inlet and outlet 216, 218, defining a second threshold of regulation and measurement of the level of the feed water volume.
[0046] Here again, the outlet 218 of the third syphon is also connected, via a pipe or intermediate chamber 222 for compression, to the inlet 224 of a respective fourth drain syphon 226.
[0047] The fourth drain syphon 226 also has an outlet 228 at a level lower than said inlet 224 and an overflow and drain threshold 230 placed between said inlet and outlet 224, 228.
[0048] In said second compression chamber 222, between said outlet 218 of the third syphon 214 and said inlet 224 of the fourth syphon 226, there is a feed mouth 232 of a respective second pressure signal generation chamber 234 wherein air is trapped and compressed, after the water, in the second control chamber 204 and the third syphon 214, has passed the level of the second measurement threshold 220 of the third syphon.
[0049] This second air trapping chamber 234 also has on the opposite side an aperture 238 which connects the chamber 234, via the opening 240 and the air pipe 242, to a second pressure switch 244 connected in turn to the control parts of the dishwasher, for example to the timer of the latter. This fact is not expressly shown in the drawings.
[0050] Naturally, here too, instead of said pressure switch 244, the second air trapping chamber 234 could have been connected to any other means suitable for interrupting the flow of feed water towards the washing drum 16 of the dishwasher.
[0051] When the pressure in said second pneumatic chamber 234 for trapping air has reached a predetermined value, the respective pressure signal triggers the second pressure switch 244. Said second pressure switch 244 thus converts said predetermined trigger pressure signal into an electric signal in input at the control device of the dishwasher which blocks the feed of water from the water supply system to the interior of the dishwasher.
[0052] The outlet 228 of the fourth drain syphon 226 communicates with the washing drum 16 of the dishwasher via the passage 245, the opening 146 in the block 18 and the external pipe 148.
[0053] The passage 245 of the second regulation section 202 and the passage 145 of the first regulation section 102 communicate one with the other and both flow into the opening 146.
[0054] As already referred, in this second preferred embodiment the gate of the aforementioned solenoid valve 200 is however present in the pipe 148.
[0055] The reference numeral 250 denotes in the figures a hole whereby the chamber 204 opens to the outside and whereby the air is progressively expelled while the water rises inside the chamber 204.
[0056] From this second preferred embodiment a further innovative aspect of the present invention can be seen.
[0057] In fact, according to a further feature of the present invention, shown in this second preferred embodiment, the device of the present invention is equipped with a safety system which triggers when all the previous control systems have failed, for example in the event of the two control pressure switches having broken down.
[0058] This first safety device comprises a filling or backflow pipe 160 downstream of the outlet 128 of said second drain syphon 126. Said backflow pipe 160 opens via an aperture 162 in a pipe 154 for connection to means for detecting water leaks and has at this aperture 162 a respective overflow threshold 164. When the latter has been passed, the water flows towards said means for detecting leakage of water 156 and allows shutting-off of the feed of water to the drum 16 of the dishwasher to be commanded.
[0059] Said means for detecting water leaks 156 may for example consist of sponges which swell when in contact with water and which cause a suitable stop contact of the dishwasher machine or other to close.
[0060] 168 in the figures denotes a hole for communication with the outside which allows the water to rise freely in the backflow pipe 160.
[0061] The presence of a solenoid valve in the common drain pipe 148, towards the washing drum 16 of the dishwasher, allows, in respect of the first preferred embodiment, all the safety levels described above to be actuated, subsequent to the first and second control levels.
[0062] As referred, known systems use safety systems which generally consist of floats which close a switch, for example a Reed switch, which define together a somewhat voluminous assembly which also requires a special electrical safety circuit which extends in the control device. On the contrary the system with several safety levels of the present invention has small size and bulk which make it particularly suitable for its integration in blocks 18 provided alongside the washing drum of dishwasher machines, and does not require the immersion in its interior of floats and electrical switches, nor the provision of electrical terminals for connection to electrical safety circuits, thus saving the costs of these components and relevant costs of assembly. Moreover any risk of breakages of the electrical safety circuit with hazardous dispersion of electrical current in the control system is thus avoided.
[0063] As shown the primary regulation section 102 has also been equipped here with a safety system against malfunctionings both of the first and of the second pressure switch 144, 244, as well as of the first safety system. The regulation section 102 has been equipped with a safety threshold 152, referred to here as second threshold, at a height higher than the first measurement threshold of the first syphon 114, as well as a pipe 154 for connection to means for detecting leaks of water 156, via an aperture 155, an opening 157 and an external pipe 159.
[0064] The water which rises inside the first control chamber 104, in the event of failure to shut off the feed of water, reaches and passes the threshold 152, and then flows towards the means 156 for detecting the leaks of water, which send a signal to the timer or control part of the dishwasher or act on any other device in order to block any feed of water to the washing drum 16 of the latter.
[0065] Moreover, as shown in the figures in this second preferred embodiment according to the present invention, the second regulation section 202 has also been equipped, like the first, with a respective safety threshold 252, referred to here as third safety threshold, at a height higher than the measurement threshold 220 of the third syphon 214 and higher than the second safety threshold 152 of the first control section 102. The water inside the second control chamber 204, similar to the procedure of the first control chamber 104, after it has reached and passed the threshold 252, flows, via an upper passage 255 for connection to said control chamber 104 of said primary regulation section 102, towards said connection pipe 154 and the means 156 for detecting leaks of water, suitable for sending a signal to the control timer of the dishwasher such as to block any feed of water to the washing drum of the latter.
[0066] This third safety system intervenes when all the previous systems of interruption mentioned previously, i.e. the first control section, the second control section and the first and second safety systems, for any reason, have not intervened.
[0067] The operation of this second preferred embodiment of the present invention is briefly as follows: the first phases of operation of the system of this second preferred embodiment are wholly similar to those of the first preferred embodiment, and we shall not therefore go into details.
[0068] As shown in Figure 4, during feeding of water to the washing drum of the dishwasher, via the nozzles 106 and 206 a proportional quantity of water is poured respectively towards the primary control chamber 104 and the secondary control chamber 204. The two chambers 104 and 204 or the respective tapping nozzles 106, 206 are shaped so that, when the water in the first control chamber 104 reaches first the first measurement level corresponding to the first measurement threshold 120 of the first syphon 114, simultaneously, the level of water in the second control chamber 204 is below the second measurement threshold 220 of the third syphon 214.
[0069] As soon as the water passes the level defined by the threshold 120 of the corresponding first syphon 114 it overflows towards the second syphon 126 in the same way as for the first preferred embodiment. Here too, following this overflow, there is strong compression of the air trapped inside the pressure chamber 134 and a pressure signal is given by the pressure switch 144 which commands the timer of the dishwasher machine to block transfer of water to the washing drum. Starting from this signal the timer likewise commands opening of the gate of the solenoid valve 200 in order to drain both the first control chamber 104 and the second control chamber 204, as shown in Figure 5.
[0070] According to the present invention, it could likewise be foreseen to delay slightly the opening of the gate of the solenoid valve 200 so as to maintain the air in the pressure chamber compressed at a level of pressure sufficient for maintaining the pressure switch 144 actuated.
[0071] Should the first regulation section 102 not start up due for example to a fault in the pressure switch 144 and, as shown in Figure 6, the water continue to be fed to the washing drum 16, provision is made for the second regulation section 202 to intervene.
[0072] As shown in Figure 7, the water rises inside the second control chamber 204 of the second section 202 as far as the second measurement threshold 220 of the third control syphon 214. In this situation the water inside the first control chamber 104 is at a somewhat low level and the whole primary system downstream thereof contains water practically in a static condition. As shown in Figure 8, after the water in the second control chamber 204 has passed the threshold 220 of the third syphon 214, this latter syphon 214 triggers and the water is returned rapidly towards the fourth drain syphon 226, similarly to the procedure of the first control section 102, rapidly flowing from the second control chamber 204 and rushing towards the second intermediate compression chamber 222 so as to compress with force, making its pressure level rise sharply, the air trapped inside the second chamber for the generation of the pressure signal 234. Thus a pressure signal is supplied, in a wholly similar manner to what occurred for the first pressure switch 144, to the second pressure switch 244, whereby interruption of the feed of water to the drum 16 of the dishwasher and opening of the gate of the solenoid valve 200 are commanded.
[0073] The pressure impulse received by the pressure switch 244, as moreover occurred for the first pressure switch 144, is of such a size that no prior calibration is required, with saving of the relevant costs.
[0074] Following this opening of the gate of the solenoid valve 200, thanks to the fact that the third and fourth syphons 214, 226 of the second regulation section 202 remain triggered, like, moreover, the first and second syphons 114, 126 of the first regulation section 102, the two control chambers 104 and 204 are totally emptied and the regulation device is ready for being filled again at a new cycle of feeding of the drum 16 of the dishwasher.
[0075] However if, as already referred, the second pressure switch 244 does not work either, it is foreseen, in this second preferred embodiment of the invention, that, as shown in Figure 9, the water, which continues to flow inside the first control chamber 104 downstream of the outlet 128 of said second syphon 126, rises again along said backflow pipe 160 until it reaches said overflow threshold 160 of said aperture for connection of the backflow pipe to the pipe 154 for connection to means for detecting water leaks 156. By continuing to rise, the water passes this threshold 164 and flows towards said means for detecting water leakage 156 and thus allows shutting-off of the feed of the water to the drum of the dishwasher and opening of the gate of the emptying solenoid valve 200 to be commanded.
[0076] If then, as already referred previously, the first safety system 164 does not operate either, for example due to clogging of the opening 162 of the backflow channel 160, as shown in Figure 10, in this second preferred embodiment provision is made for the water to rise inside the control chambers 104 and 204 until it reaches the level of the second upper safety threshold 152 of the first control chamber 104, having passed which it overflows in the pipe 154 by means of which it reaches the means for detecting a water leak 156 which are connected to the control timer of the dishwasher and thus feeding of the water to the washing drum 16 can be blocked and the gate of the solenoid valve 200 opened in order to trigger in this other manner the process of emptying of the control chambers 104 and 204, as shown in Figure 10.
[0077] If this second safety system does not trigger either, for example due to the fact that the first control chamber 104 is clogged at the top and the mouth 162 of the backflow channel is also clogged, as shown in Figure 11, the water rises inside the second control chamber until it reaches the respective second safety threshold 252, having passed which it overflows via the passage 255 into the pipe 154 by means of which it reaches the means for detecting a water leak 156 and thus the feeding of water to the washing drum 16 is blocked with simultaneous opening of the gate of the solenoid valve 200 which triggers the process of emptying of the control chambers 104 and 204.
[0078] Thus a system has been provided for controlling the water for feeding the washing drum of dishwasher machines which has several possibilities of intervention, so as to avoid any risk of malfunctioning and failure to stop feeding of water to the dishwasher. Any damage arising from the inappropriate outflow of water from the dishwasher is thus avoided.
[0079] In order to obtain a required pressure impulse in the first and second air chambers it has been demonstrated experimentally that said first and third control syphons 114, 214 must be dimensioned in such away that the volume of water which can be contained in the first section of said first and third syphons which is between the respective inlet 116, 216 and the respective overflow threshold 120, 220 must be greater or substantially equal, that is to say of the order of magnitude of the volume of air contained in the respective pressure signal generation chambers 134, 234. In this way the head of water is achieved which triggers with prompt and reliable intervention the respective pressure switches 144, 244.
[0080] The height of the first and third syphons 114, 214 could be around 20-25 cm, while the second and fourth drain syphons 122, 226, smaller in size, could have a height of around 20-30 mm. Said second and fourth drain syphons 126, 226 are shaped somewhat small both in order to limit the overall dimensions to a maximum, that is to say the dimensions of the regulation device, and so that the latter do not create excessive resistance to the triggering of evacuation of the water from the respective control sections.
[0082] This third preferred embodiment of the present invention is wholly similar to the second preferred embodiment described above from which it is mainly distinguished due to the fact that decalcified water is fed inside the control sections 102, 202. This allows those disadvantages to be overcome which occur when hard water taken directly from the water supply system is used, that is to say the fact that encrustations form inside the regulation device which in the long term jeopardise its operation, as well as due to the fact that in this way the water which is drained, at the end of each cycle of feeding from said control chambers in the washing drum 16 of the dishwasher, is in a decalcified state which does not encrust the washing drum and does not interfere with the washing process, that is to say it does not interact negatively with the washing detergent.
[0083] For this purpose, according to the third preferred embodiment shown here, the pipe 300, for feeding the water taken from the mains by means of the tap 20, extends in the block 18 which houses the device of the present invention in a first section 302, in which the mains water enters via the opening 303, comprising an air break 304 which conveys the "hard" mains water via the opening 306 to the resins tank 307. The decalcified water flowing out of the resins tank 307 enters via an opening 308 a section 310 of the pipe for feeding water from which it flows via the opening 312 and then reaches the washing drum 16 of the dishwasher.
[0084] According to the preferred embodiment shown here, said tapping nozzles 106 and 206 for filling the control chambers 104 and 204 are provided on the part of the pipe 310 for feeding water for filling the washing drum which is downstream of the tank for the decalcification resins, and therefore feed decalcified water only in the first and second regulation sections 102 and 202.
[0085] Moreover this third preferred embodiment of the present invention comprises a first control section 102 which has the possibility of changing the controlled level of water feed in the washing drum 16. For this purpose said control chamber 104 has been provided with a filling store or volume 404 communicating below via the aperture 406 with the main portion 104 of said control chamber. Said store 404 has an end section 404' which has a port 408 which connects said store 404 with the outside. Said port 408 is normally closed by a gate (not shown) controlled by a coil 410 of a solenoid valve 412. When the volume of water contained in the drum of the dishwasher is to be increased, for example doubled, the timer of the dishwasher forces the coil of the solenoid valve which moves the closure gate and opens the port 408. The store 404 can thus be filled with water and the level 120 of the first control threshold is reached by the water in a longer time, with the level of the water in the second control chamber 204 which is still well below the level of the respective second control threshold 220, obtaining a second level of filling of the washing drum 16 of the dishwasher higher than that which can be obtained in normal conditions with the port 408 for communicating with the outside closed and the supplementary store 404 which remains virtually empty of water.
[0086] The system of regulation of the level of water feed of the present invention is extremely precise. Indeed the tolerance relating to triggering of the main syphons is mainly of the order of only 2 mm, so that it is sufficient to dimension adequately the size of the control chambers and of the tapping nozzles in order to obtain rapid increases in the level of water in these chambers comparable with the value of the trigger tolerance of the control syphons.
[0087] The block 18 containing the device of the present invention is preferably manufactured in polymeric material by sealing with a hot blade two detached and matching parts, one of which has projections defining the channels and the side walls of the tanks or chambers of the device. Such a manufacturing process is in any case wholly traditional.
1. A device for the regulation of the volume of water for feeding the washing drum (16)
of a dishwasher machine (10) and the like, having a section (102) for control of the
water feed comprising a first chamber (104) for control of the volume of water for
feeding the washing drum wherein a quantity of water is fed proportional to the volume
of water for feeding the washing drum (16), characterized in that it further comprises
a first drain syphon (114) having an inlet (116) communicating with said control chamber
(104) at the base of the latter, an outlet (118) and an overflow threshold (120) defining
a threshold of measurement of the feed water volume; an intermediate compression chamber
(122) connected to said outlet of the first drain syphon (114) and to the inlet (124)
of a second drain syphon (126) of the device; a pressure signal generation chamber
(134) communicating for an air compression with said intermediate compression chamber
(122) whereby air is trapped and compressed in said primary pressure signal generation
chamber (134) after the water has passed the measurement threshold (120) of said first
drain syphon (104), said pressure signal generation chamber (134) providing a pressure
signal to a pressure sensing element (144) whereby said pressure signal is converted
into a command signal suitable for blocking feeding of water to the washing drum (16)
of the dishwasher; said second drain syphon (126) having also a respective outlet
(128) and a respective overflow and drain trigger threshold (130), said outlet (128)
of the second drain syphon (126) directly communicating with the washing drum (16)
of the dishwasher in which it drains the water from inside the control section (102)
on passing of said drain threshold (130) of the second drain syphon (126).
2. A device according to claim 1, characterized in that the volume of water which can
be contained in the portion of the first drain syphon (114) of the control section
(102) between the inlet (116) and the overflow threshold (126) is greater or substantially
equal to the volume of air contained in the pressure signal generation chamber (134).
3. A device according to any of previous claims, characterized in that said outlet (128)
of said second drain syphon (126) is connected to said washing drum (16) of the dishwasher
by means of a normally closed gate part; and in that it comprises a second section
(202) for controlling the water feed comprising a second control chamber (204) for
controlling the volume of water for feeding the washing drum (16), wherein a quantity
of water proportional to the volume of water for feeding the washing drum (16) is
fed; a respective third drain syphon (214) having an inlet (216) communicating with
said second control chamber (204) at the base of the latter, an outlet (218) and a
respective overflow threshold (220) for a second measurement of the feed water volume
which can be reached by the upper surface of water after reaching of the threshold
for the first measurement of the water feed level of the primary control section (102);
a second compression chamber (222) connected to said outlet (218) of the third drain
syphon (214) and to the inlet (224) of a fourth drain syphon (226); a second pressure
signal generation chamber (234) communicating with said second compression chamber
(222) whereby air is trapped and compressed in said second pressure signal generation
chamber after the water has passed the second measurement threshold (220) of said
third drain syphon (214); said fourth drain syphon (226) also having a respective
outlet (228) and a respective drain trigger and overflow threshold (230), said outlet
(228) of the fourth drain syphon (226) communicating with the washing drum (16) of
the dishwasher by means of said normally closed gate part; said second pressure signal
generation chamber (234) communicating with a second pressure sensing element (244)
whereby said pressure signal is converted into a command signal suitable for blocking
feeding to the washing drum (16) and opening said emptying gate in order to empty
the water contained in the two control sections (102, 202).
4. A device according to claim 3, characterized in that the volume of water which can
be contained in the portion of the third drain syphon (214) of the second control
section (202) between the inlet (216) and the overflow threshold (220) is greater
or substantially equal to the volume of air contained in the second pressure signal
generation chamber (234).
5. A device according to any of previous claims, characterized in that a backflow pipe
(160) is provided downstream of the outlet (128) of said second drain syphon (126)
of the first control section (102), said backflow pipe (160) being connected via a
respective overflow threshold (164) to means for detecting leaks of water (156).
6. A device according to any of previous claims, characterized in that said control chamber
(104) is connected to means for detecting leaks (156) of water via a first safety
threshold (152) at a height greater than said measurement threshold (120) of the first
drain syphon (114) of the control section (102).
7. A device according to any of previous claims, characterized in that said second control
chamber (204) is connected to means (156) for detecting leaks of water via a second
safety threshold (252) at a height greater than said measurement threshold (220) of
the third drain syphon (214) of the second control section (202).
8. A device according to claims 6 and 7, characterized in that said first and second
safety thresholds (152, 252) of the first and second control sections (102, 202) flow
into the same pipe (154)for connection to means (156) for detecting leaks of water.
9. A device according to any of previous claims, characterized in that said pipe (300)
for feeding water of the washing drum (16) comprises a first part (302) for feeding
mains water to a decalcifier (307) and a second part (310) for feeding decalcified
water to the washing drum (16); and in that tapping nozzle means (106) for feeding
water to the control section (102) are provided in said second section (202) of the
feed pipe, so that only decalcified water is fed into the control section (102).
10. A device according to claim 9, characterized in that tapping nozzle means (206) for
feeding water to the second control section (202) is provided in said second part
(310) of the feed pipe (300), so that only decalcified water is fed in the second
control section (202).
11. A device according to any of previous claims, characterized in that said first and
second syphons (104, 126) of the control section (102) are arranged one on top of
the other, enclosing between them said air trapping chamber (134), so as to provide
an arrangement which occupies a small volume.
12. A device according to any of previous claims, characterized in that it comprises a
supplementary filling store (404) communicating with said first control chamber and
commandable means (412) suitable for allowing the flow of water from said control
chamber (104) inside of said supplementary filling store (404).