AUSTRALIA Patents Act COMPLETE SPECIFICATION (ORIGINAL) Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: Premark FEG L.L.C. Actual Inventor(s): Gianluca Pardini Address for Service and Correspondence: PHILLIPS ORMONDE & FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: LOW-WATER-CONSUMPTION RINSING AND/OR WASHING DEVICE, AND DISHWASHING MACHINE FEATURING SUCH A DEVICE Our Ref: 840909 POF Code: 1545/291215 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1la LOW-WATER-CONSUMPTION RINSING AND/OR WASHING DEVICE, AND DISHWASHING MACHINE FEATURING SUCH A DEVICE This application claims priority from TO2007A000753 filed 23 October 2007, the contents of which are to be 5 taken as incorporated herein by this reference. The present invention relates to a rinsing and/or washing device for an electric household appliance, specifically for a dishwashing machine of the professional type, able to reduce the consumption of 10 water. The invention further relates to electric household appliances equipped with such a device. EP1050263 discloses a washing/rinsing device for a dishwashing machine including a rotating arm provided with spraying nozzles and epicyclic movement, in order 15 to perform a better distribution of washing/rinsing fluid inside the washing chamber of the dishwashing machine, usually accessible through a front pivoting door. However, the device of EP1050263, in addition to 20 being costly and complex in manufacture, is large dimensionally and does not solve the problem of reducing the amount of water needed by the machine for carrying out the washing cycle and, in particular, the rinsing cycle, while simultaneously obtaining good washing 25 results on the dishes being washed. Indeed, a study internally carried out by the Applicant has recently brought to light that dishwashing P:\Su-Yin\Secretaria1 Work\Speci\940909 Amended Page.doc lb machines manufactured nowadays, in order to ensure a "minimum guaranteed" delivery of water in all points of P:\Su-Yin\5eCretarial Work\Speci\040909 Amended Pages.doc 2 the washing chamber, deliver more water than actually needed in many points of the chamber itself. This drawback causes a considerable waste of water resources and of energy resources, in particular in 5 dishwashing machines for professional use (for bars, restaurants, communities, etc.) which, even if largely working with recirculated water (closed cycle), must however resort to mains water (open cycle) at least for the rinsing cycle and must heat the washing and rinsing 10 water before delivering it onto the dishes at relatively high temperatures for hygienic reasons. It would be desirable to provide an improved rinsing and/or washing device for an electric household appliance, in particular a dishwashing machine for 15 professional use, which overcomes one or more of the aforesaid drawbacks. Thus, it would be desirable to provide an improved rinsing and/or washing device that allows a reduction of water and energy consumption of the dishwashing machine, in particular during the 20 rinsing cycle, and at the same time, which is simple and cost effective to be manufactured and managed, of reduced size and high reliability, in particular with regards to possible obstructions in use of the water delivering jets. It would also be desirable to provide a 25 dishwashing machine provided with such a device which, therefore, has reduced energy and water consumptions. According to the invention, a rinsing and/or P:\Su-Yin\Secretaria1 Work\Speci\840909 Amended Pages.doc 3 washing device for an electric household appliance, in particular a dishwashing machine, comprises a rinsing and/or washing device for an electric household appliance, in particular a dishwashing machine, 5 comprising at least one arm rotationally mounted about a generally vertical axis in a washing chamber of the electric household appliance, e.g. immediately either over or under a container basket of the dishes to be washed, the arm delimiting a cavity therein connected in 10 use to delivering means of a pressurized service fluid, e.g. a washing and/or rinsing fluid, of the electric household appliance and being provided with a plurality of spraying nozzles arranged and oriented, in use, towards the dishes to be washed, reciprocally spaced in 15 the direction of length of the arm and communicating with the internal cavity of the latter, so as to determine in use the exiting of the service fluid from the arm in form of jets directed against said dishes; wherein said arm is shaped so that its opposite ends 20 radially and overhangingly extend from the rotation axis, in a manner diametrically opposite to the rotation axis itself; and, in combination, so that the number, the size and the position of the existing nozzles are chosen so that the total flow rate of the service fluid 25 delivered in use by the nozzles at each concentric 4 circumference which the same nozzles trace about the rotation axis of the arm during a complete rotation of the same is an increasing function of the radius of said circumference; and wherein said arm has an assembly 5 portion for securing it to said rotation axis arranged essentially on the middle line of the arm itself, so that opposite longitudinal portions of the arm, provided with said nozzles and ending with said opposite ends of the arm, protrude in use in an essentially symmetric 10 manner from the assembly portion in radial direction with respect to the rotation axis; wherein said arm is provided only with first nozzles adapted to deliver in use a first predetermined flow rate of service fluid; and with second nozzles adapted to deliver in use a 15 second predetermined flow rate of service fluid, smaller than said first flow rate; a first of said opposite longitudinal portions of the arm carrying - one said second nozzle arranged at a predetermined radial distance from the assembly portion so that this traces 20 in use a first circumference about said rotation axis, and - a pair of first nozzles arranged in tandem at a radial distance from the assembly portion so that each of them respectively traces in use a second and a third circumference about said rotation axis; and wherein, in 25 combination, a second longitudinal portion of the arm, 5 opposite to the first, carries - one said first nozzle arranged at a radial distance from the assembly portion so that this traces in use a fourth circumference about said rotation axis; - one said second nozzle arranged at 5 a radial distance from the assembly portion so that this traces in use said second circumference about said rotation axis; and - one said first nozzle arranged at a radial distance from the assembly portion so that this traces in use said third circumference about said 10 rotation axis. In this manner, the zones of the basket closest to the rotation axis of the arm are reached by less water, while more water is directed towards the furthermost zones, to reach which the nozzles of the arm, during the 15 rotation of the same, must cover a larger area and, thus, must necessarily have a lower water delivery "density" (ml/cmq), with the flow rate being equal. By appropriately balancing the flow rates during the design of the arm and of the nozzles thereof, it is thus 20 possible to obtain an essentially constant water delivery "density" throughout the dish-holding basket. Assuming to always use the minimum amount of water deemed sufficient to obtain adequate cleaning results (approximately 2.7 litres per basket), simple 25 calculations allow to establish that by means of the 5a device of the invention a saving of water, which may reach even 30% in the rinsing cycle, may be obtained, with a consequent, even drastic reduction of water consumptions and, of energy consumptions of the 5 dishwashing machine equipped with such a device. An electric household appliance, in particular a front-loading dishwashing machine may be provided comprising a washing chamber accommodating at least one container basket of the dishes to be washed, and 10 delivering means of a pressurized service fluid towards an inlet head arranged in the washing chamber and having a symmetry axis thereof arranged in the washing chamber in a substantially vertical position, wherein the appliance comprises a device of the above kind, wherein 15 said arm is idly and fluid-tightly mounted on said inlet head with a central assembly portion thereof, preferably immediately either over or under said basket. The arm may be provided with only two types of nozzles, namely with first nozzles, adapted to deliver 20 in use a first predetermined flow rate of service fluid, and second nozzles adapted to deliver in use a second predetermined flow rate of service fluid, lower than the first flow rate; and the nozzles are arranged along opposite longitudinal portions of the arm, which extend 25 radially and overhangingly from a central securing 5b portion of the arm to the rotation axis of the same so that at least one nozzle of a first of the opposite longitudinal portions of the arm is arranged in a radially symmetric position with respect to at least one 5 nozzle of a second of the opposite longitudinal portions of the arm, so as to trace in use the same circumference traced in use by the nozzle of the second longitudinal portion of the arm and therefore may add this to its own water flow rate. 10 In this manner, it is possible to obtain the desired water distribution with only two types of different nozzles (instead of with a plurality of 6 nozzles of progressively increasing flow rate arranged at progressively increasing distances from the rotation axis), as long as these are appropriately positioned in an asymmetric manner along the arm so that, for certain 5 circumferences they trace in use, the flow rates delivered thereby are appropriately added, while for other circumferences this does not occur. On one hand, this implies a reduction of production and assembly costs of the washing device according to the invention 10 and, on the other hand, avoids the risk that nozzles of excessively small flow rate (thus with a reduced water passage section) may be obstructed in use due to the dirt which is removed from the dishes. Further advantages of the invention will be 15 apparent from the following description of a non limitative embodiment thereof, provided only by way of example and with reference to the figures of the accompanying drawing, in which: - figure 1 diagrammatically shows a perspective 20 view of a dishwashing machine provided with a washing device manufactured according to the invention; - figure 2 diagrammatically shows a side elevation view of the washing device used in the dishwashing machine in figure 1 compared to a graph which provides 25 for the distribution of the washing/rinsing water obtainable according to the invention; and P:\Su-Yin\SecretarIl Work\Speci\840909 Aended Pages.doc 6a - figure 3 diagrammatically shows a bottom plan view of the washing device in figures 1 and 2. In figures from 1 to 3, numeral 1 indicates as a whole a rinsing and/or washing device for an electric 5 household appliance 2, in particular a dishwashing machine for professional use, of the front loading type in the example shown. The dishwashing machine 2 comprises in particular a washing chamber 3 accommodating at least one container 10 basket 4 (known) for the dishes 5 to be washed, the washing device 1 and delivering means 7 of a pressurised service fluid 8, e.g. washing and/or rinsing water, towards the device 1, in this case towards an inlet head P:\Su-Yin\Secretarial Work\Speci\840909 Ameded Pages.doc 10 arranged in the washing chamber 3 with its own symmetry axis A arranged essentially vertical and connected to the washing/rinsing device 1 in the manner disclosed below. 5 The delivering means 7 of the pressurized water are known and comprise, in this case, a pump 11, a tank 12 in which the water delivered onto the dishes 5 through the inlet head 10 and the device 1 is collected in use, and network water feeding means 13, the pump 11 being 10 able to use both the network water and the water in the tank 12. The device 1 comprises at least one arm 20 rotationally mounted about axis A, which is generally vertical, within the washing chamber 3 of the electric 15 household appliance 2, e.g. in a preferred embodiment, immediately over (or under) the container basket 4, in this case, idly and fluid-tightly mounted in a known manner and thus not described in detail for simplicity, on the inlet head 10 with its own central assembly 20 portion 21. The arm 20 delimits therein a cavity 22 (figure 3) connected in use to the delivering means 7 of the water through the inlet head 10 and is provided with a plurality of spraying nozzles 23 arranged oriented in 25 use towards the dishes 5 to be washed, reciprocally spaced in the sense of length of the arm 20 -and communicating with the internal cavity 22 of the latter, so as to determine in use the exiting of the service 8 fluid 8 (water or water and detergent) from arm 20 in the form of jets 24 (figure 2) directed towards the dishes 5. In accordance with the description, the arm 20, 5 according to a first aspect of the invention, is shaped so that its opposite ends 25,26 radially and overhangingly extend, in use, from rotation axis A in a manner diametrically opposite with respect to the rotation axis A itself; in combination with such a 10 feature, the arm 20 is constructed so that the number, the size and the position of the existing nozzles 23 is such that the total flow rate of the service fluid 8 delivered in use by the nozzles 23 at each ideal concentric circumference C (diagrammatically shown with 15 a dashed line in figure 3) which is traced by the nozzles 23 themselves about the rotation axis A of the arm 20 during a complete rotation of the same, is an increasing function of the radius of such a circumference. 20 Specifically, the total flow rate of the service fluid 8 delivered in use by the nozzles 23 at each concentric circumference C which they trace about the rotation axis A of the arm 20 during a complete rotation of the same, increases in an essentially linear manner 25 with the radius of the circumferences C, as diagrammatically shown in the graph in figure 2. Substantially, according to the invention, the arm 20 is designed to deliver by means of the nozzles 23 9 more water the farther the distance of the nozzles 23 from the rotation axis A is. Such a result might be obtained by an arm however shaped and mounted, provided that it is equipped with nozzles of gradually larger 5 opening according to their distance from the rotation axis A; however, in such a manner, the manufacturing cost of the arm 20 would be relatively high and, above all, the opening of the nozzles closest to the axis A would be so small that they risk being obstructed in use 10 by the dirt removed from the dishes 5. Therefore, according to one aspect of the invention, the assembly portion 21 to the inlet head 10 is arranged on the middle line of the arm 20, so as to split the arm into two opposite longitudinal portions 15 27,28, which are the only parts of the arm 20 provided with the nozzles 23; the portions 27,28 end, on the opposite side of the assembly portion 21, with the ends 25,26, which may be provided (figure 3) with propulsion nozzles 30 appropriately oriented and constructed so as 20 to determine a tangential pouring of service fluid 8 therethrough, so that the nozzles 30 represent in use reaction thrust generating means for determining the rotation of the arm 20 about the axis A. Alternatively, the nozzles 30 may be missing and 25 therefore the nozzles 23 will be oriented slightly askew with respect to axis A, so as to further determine in use, by P:\Su-YIn\Secretarial Work\Speci\840909 Amended Page.doc 10 means of the ejection from the washing/rinsing jets 24, the reaction rotation movement of the arm 20 about the axis A. In this manner, the assembly portion 21 serves the 5 two-fold function of securing, in use, the arm 20 to the rotation axis A so that the longitudinal portions 27,28 protrude in use in an essentially symmetric manner from the assembly portion 21 in a radial direction with respect to the rotation axis A; and of making the fluid 10 tight connection between the inlet head 10 and the corresponding delivering means 7 of the service fluid 8 and the internal cavity 22 of the arm 20. The latter is obtained either by manufacturing the portions 27,28 as tubular elements closed at the ends 25,26, or by 15 manufacturing the portions 27,28 by means of two reciprocally coupled concave parts (e.g. made of pressed metal sheet). In combination with the structure of the arm 20 described heretofore, the nozzles 23 are arranged along 20 the opposite longitudinal portions 27,28 of the arm 20 so that at least one nozzle 23 of the portion 27 is arranged in a radially symmetric position with respect to at least a corresponding nozzle 23 of the portion 28, so that these two nozzles 23 trace in use the same 25 circumference C, therefore adding their flow rates of service fluid 8 towards the basket 4, meaning that the jets 24 produced therefrom will insist, in use, on the same area (in this case, defined by a circular crown 11 centred on axis A) of the basket 4. According to a preferred but not limitative embodiment of the invention, the arm 20 is provided with only two different types of nozzles 23, namely with 5 nozzles 23b adapted to deliver in use a first predetermined flow rate ql of fluid 8, and with nozzles 23c adapted to deliver in use a second predetermined flow rate q2 of service fluid 8, smaller than the flow rate ql (the relation ql > q2 thus applies). 10 The nozzles 23b and 23c are further arranged according to an asymmetric configuration with respect to axis A so as to generate *in use, with the nozzles 23b and 23c of the portion 27, jets 24 which may be added (meaning that they insist on the same areas of the 15 basket 4 in use) or not, to the jets 24 generated by the nozzles 23b and 23c of the portion 28. In particular, the longitudinal portion 27 of the arm 20 carries a nozzle 23c arranged at a predetermined radial distance from the assembly portion 21 so as this 20 traces in use a first circumference Cl of radius R1 about the rotation axis A, and a pair of nozzles 23b arranged in tandem at a radial distance from the assembly portion 21 so that each of them traces in use a second circumference C2 of radius R2 greater than Rl and 25 a third circumference C3 of radius R3 greater than R2 about the rotation axis A, respectively. The opposite longitudinal portion 28 of the arm 20 instead carries a nozzle 23b arranged at a radial 12 distance from the assembly portion 21 so that this traces in use a fourth circumference C4 of radius R4 about the rotation axis A; gradually moving away from axis A, there is a second nozzle 23c arranged at a 5 radial distance from the assembly portion 21 so that this second nozzle 23c of the portion 28 traces in use the same circumference C2 traced by a nozzle 23b of the portion 27; and a third nozzle 23b arranged at a radial distance from the assembly portion 21 so that it traces 10 in use the same circumference C3 traced by a nozzle 23b of the portion 27. The position of the first nozzle 23b (in the sequence counted from axis A) of the portion 28 is finally chosen so that the radius R4 of the 15 circumference C4 which it describes in use about the axis A is greater than the radius R1 of the circumference Cl traced in use by the first nozzle (again according to a sequence counted from the axis A) of the portion 27 and smaller than the radius R2 of the 20 circumference C2 traced in use by both the second nozzle 23b of the portion 27, and the second nozzle 23c of the portion 28. In this manner, the areas of the basket 4 progressively further away from the axis A defined by 25 circular crowns placed at the circumferences Cl-C4 and each having a radial width depending on the opening angle of the jets 24 generated by the nozzles 23 tracing each circumference each time (therefore, areas of 13 progressively larger dimensions), are in use sprinkled by progressively increasing flow rates of service fluid 8, called Q1, Q2, Q3, Q4, the values of which will depend on the position (circumferences Cl-C4) and type 5 (nozzles 23b and 23c) of the nozzles 23 from which each circular crown is sprinkled in use. According to the description and the illustration in figure 3, the aforesaid overall flow rates will have the following values: 10 Q1 = q2; Q2 = ql; Q3 = ql + q2 Q4 = ql + ql It is thus apparent that by appropriately choosing 15 the position and sizes of the nozzles 23, each zone of the basket 4 may be invested in use by a total amount of water L which remains approximately constant, regardless of the distance from the rotation axis A which is taken into account. 20 Throughout the description and claims of this specification the word "comprise" and variations of that word, such as "comprises" and "comprising", are not intended to exclude other additives or components or integers. 25 The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood ?:\Su-Yin\Secretarial Work\SpecL\840909 Aended Pages.doc 14 that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description. 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