Low-water-consumption rinsing and/or washing device, and dishwashing machine featuring such a device

Abstract

 A rinsing and/or washing device (1) for an electric household appliance (2), consisting in an arm (20) rotationally mounted about a generally vertical axis (A) in a washing chamber (3) of the electric household appliance, e.g. immediately either over or under a container basket (4) of the dishes (5) to be washed, the arm delimiting a cavity (22) therein connected in use to delivering means (7) of a pressurized service fluid (8) and being provided with a plurality of spraying nozzles (23) arranged and oriented, in use, towards the dishes to be washed, reciprocally spaced in the direction of length of the arm and communicating with the internal cavity of the latter; wherein opposite ends (25,26) of the arm radially and overhangingly extend, on opposite sides, from the rotation axis (A), this being preferably positioned at the middle line of the arm (20); and wherein the number, the size and the position of the nozzles (23b,23c) are chosen so that the flow rate (Q1-Q4) of the washing fluid delivered in use by the nozzles (23b,23c) along each concentric circumference (C1-C4) which the same trace about the rotation axis (A) of the arm during a complete rotation of the same is an increasing function, preferably in an essentially linear manner, of the radius (R1-R4) of the circumference itself.

Description

[0001] 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 drastically reduce the consumption of water. The invention further relates to the electric household appliance equipped with such a device.

[0002] A washing/rinsing device for a dishwashing machine including a rotating arm provided with spraying nozzles and epicyclic movement in order to perform a better distribution of washing/rinsing fluid inside the washing chamber of the dishwashing machine, usually accessible through a front pivoting door, is known from EP1050263.

[0003] However, the known device, in addition to be costly and complex to be manufactured, has considerable dimensions and in any case does not solve the problem of drastically reducing the amount of water needed by the machine for carrying out the washing cycle and, in particular, the rinsing cycle, simultaneously obtaining good washing results on the dishes to be treated.

[0004] Indeed, a study internally carried out by the Applicant has recently brought to light that all the dishwashing machines manufactured nowadays, in order to ensure a "minimum guaranteed" delivery of water in all points of the washing chamber, deliver more water than needed in many points of the chamber itself. This drawback causes a considerable waste of water resources and, above all, of energy resources, in particular in dishwashing machines for professional use (for bars, restaurants, communities, etc.) which, even if largely work with recirculated water (closed cycle), must however resort to the water from the water network (open cycle) at least for the rinsing cycle and, in all cases, must heat the washing and rinsing water before delivering it onto the dishes at relatively high temperatures for hygienic reasons.

[0005] It is the object of the present invention to provide an improved rinsing and/or washing device for an electric household appliance, in particular a dishwashing machine for professional use, which overcomes the aforesaid drawbacks, allowing a high reduction of water and energy consumptions of the dishwashing machine, in particular during the 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 is a further object of the invention to provide a dishwashing machine provided with such a device which, therefore, has reduced energy and water consumptions.

[0006] According to the invention, a rinsing and/or washing device for an electric household appliance, in particular a dishwashing machine, is thus provided as defined in claim 1.

[0007] The invention further relates to an electric household appliance, as defined in claim 11.

[0008] In particular, the device according to the invention comprises 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 delimits a cavity therein connected in use to delivering means of a pressurized service fluid, e.g. a washing and/or rinsing fluid, of the electric household appliance and is provided with a plurality of spraying nozzles arranged and oriented, in use, towards the dishes to be washed, reciprocally spaced in 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 the dishes.

[0009] According to the main aspect of the invention, the arm is shaped so that its opposite ends radially and overhangingly extend from the rotation axis, in a manner diametrically opposite to the rotation axis itself, according to a configuration which is generally known; however, in combination with such a feature, the number, the size and the position of the existing nozzles are chosen so that the total flow rate of the service fluid delivered in use by the nozzles present on the arm at each concentric circumference that the same nozzles trace about the rotation axis of the arm during a complete rotation of the same is an increasing function, in particular linearly increasing, of the radius of such a circumference.

[0010] 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 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 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 calculations allow to establish that by means of the device of the invention a saving of water, which may reach even 30% in the rinsing cycle, may be obtained, with a consequent, drastic reduction of water consumptions and, above all, of energy consumptions of the dishwashing machine equipped with such a device.

[0011] According to a further aspect of the invention, the arm is provided with only two types of nozzles, namely with first nozzles, adapted to deliver 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 radially and overhangingly from a central securing 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 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.

[0012] 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 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 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 drastic reduction of production and assembly costs of the washing device according to the invention 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.

[0013] Further objects and advantages of the invention will be 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 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 for the distribution of the washing/rinsing water obtainable according to the invention; and
• figure 3 diagrammatically shows a bottom plan view of the washing device in figures 1 and 2.

[0014] In figures from 1 to 3, numeral 1 indicates as a whole a rinsing and/or washing device for an electric household appliance 2, in particular a dishwashing machine for professional use, of the front loading type in the example shown.

[0015] The dishwashing machine 2 comprises in particular a washing chamber 3 accommodating at least one container 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 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.

[0016] 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 able to use both the network water and the water in the tank 12.

[0017] 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 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 portion 21.

[0018] 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 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 fluid 8 (water or water and detergent) from arm 20 in the form of jets 24 (figure 2) directed towards the dishes 5.

[0019] In accordance with the description, the arm 20, 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 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 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.

[0020] 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 with the radius of the circumferences C, as diagrammatically shown in the graph in figure 2.

[0021] Substantially, according to the invention, the arm 20 is designed to deliver by means of the nozzles 23 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 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 by the dirt removed from the dishes 5.

[0022] Therefore, according to a non negligible aspect of the invention, the assembly portion 21 to the inlet head 10, known per se, is essentially arranged on the middle line of the arm 20, so as to split the arm into two opposite longitudinal portions 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 (known per se) appropriately oriented and constructed so as 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.

[0023] Alternatively, the nozzles 30 may be missing and therefore the nozzles 23 (according to a method which is known per se) will be oriented slightly askew with respect to axis A, so as to further determine in use, by means of the ejection from the washing/rinsing jets 24, the reaction rotation movement of the arm 20 about the axis A.

[0024] In this manner, the assembly portion 21 serves the 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-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 manufacturing the portions 27,28 by means of two reciprocally coupled concave parts (e.g. made of pressed metal sheet).

[0025] In combination with the structure of the arm 20 described heretofore, the nozzles 23 are arranged along 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 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 centred on axis A) of the basket 4.

[0026] 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 nozzles 23b adapted to deliver in use a first predetermined flow rate q1 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 q1 (the relation q1 > q2 thus applies).

[0027] 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 basket 4 in use) or not, to the jets 24 generated by the nozzles 23b and 23c of the portion 28.

[0028] 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 traces in use a first circumference C1 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 R1 and a third circumference C3 of radius R3 greater than R2 about the rotation axis A, respectively.

[0029] The opposite longitudinal portion 28 of the arm 20 instead carries a nozzle 23b arranged at a radial 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 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 in use the same circumference C3 traced by a nozzle 23b of the portion 27.

[0030] 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 circumference C4 which it describes in use about the axis A is greater than the radius R1 of the circumference C1 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 circumference C2 traced in use by both the second nozzle 23b of the portion 27, and the second nozzle 23c of the portion 28.

[0031] In this manner, the areas of the basket 4 progressively further away from the axis A defined by circular crowns placed at the circumferences C1-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 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 C1-C4) and type (nozzles 23b and 23c) of the nozzles 23 from which each circular crown is sprinkled in use.

[0032] According to the description and the illustration in figure 3, the aforesaid overall flow rates will have the following values:

Q1 = q2;

Q2 = q1;

Q3 = q1 + q2

Q4 = q1 + q1

[0033] It is thus apparent that by appropriately choosing 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.

Claims

1. A rinsing and/or washing device (1) for an electric household appliance, in particular a dishwashing machine (2), comprising at least one arm (20) rotationally mounted about a generally vertical axis (A) in a washing chamber (3) of the electric household appliance, e.g. immediately either over or under a container basket (4) of the dishes (5) to be washed, the arm (20) delimiting a cavity (22) therein connected in use to delivering means (7) of a pressurized service fluid (8), e.g. a washing and/or rinsing fluid, of the electric household appliance and being provided with a plurality of spraying nozzles (23) arranged and oriented, in use, towards the dishes to be washed, reciprocally spaced in the direction 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 fluid from the arm in form of jets (24) directed against said dishes; wherein said arm (20) is shaped so that its opposite ends (25,26) radially and overhangingly extend from the rotation axis (A), in a manner diametrically opposite to the rotation axis itself; characterized in that, in combination, the number, the size and the position of the existing nozzles (23b,23c) were chosen so that the total flow rate (Q1-Q4) of the service fluid delivered in use by the nozzles (23b,23c) at each concentric circumference (C1-C4) which the same nozzles trace about the rotation axis (A) of the arm (20) during a complete rotation of the same is an increasing function of the radius (R1-R4) of said circumference (C1-C4).

2. A device (1) according to claim 1, characterized in that the total flow rate (Q1-Q4) of the service fluid delivered in use by the nozzles (23b,23c) at each concentric circumference (C1-C4) which the same trace about the rotation axis of the arm (20) during a complete rotation of the same increases in an essentially linear manner with the radius (R1-R4) of said circumference (C1-C4).

3. A device (1) according to claim 1 or 2, characterized in that said arm (20) has an assembly portion (21) for securing it to said rotation axis (A) arranged essentially on the middle line of the arm itself, so that opposite longitudinal portions (27,28) of the arm, provided with said nozzles (23) and ending with said opposite ends (25,26) of the arm, protrude in use in an essentially symmetric manner from the assembly portion (21) in radial direction with respect to the rotation axis (A).

4. A device (1) according to claim 3, characterized in that said nozzles (23b,23c) are arranged along said opposite longitudinal portions (27,28) of the arm so that at least one nozzle (23) of a first (27) of said opposite longitudinal portions of the arm is arranged in a radially symmetric position with respect to at least one nozzle (23) of a second (28) of said longitudinal portions of the arm, so that said at least one nozzle (23b,23b) of said first longitudinal portion (27) of the arm traces in use the same circumference (C2,C3) traced in use by at least one nozzle (23c,23b) of said second longitudinal portion (28) of the arm (20).

5. A device (1) according to claim 3 or 4, characterized in that said arm (20) is provided with first nozzles (23b) adapted to deliver in use a first predetermined flow rate (q1) of service fluid; and with second nozzles (23c) adapted to deliver in use a second predetermined flow rate (q2) of service fluid, smaller than said first flow rate (q1).

6. A device (1) according to claim 5, characterized in that said arm (20) is provided only with said first and second nozzles (23b,23c).

7. A device (1) according to claim 5 or 6, characterized in that a first (27) of said opposite longitudinal portions (27,28) of the arm (20) carries one said second nozzle (23c) arranged at a predetermined radial distance from the assembly portion (21) so that this traces in use a first circumference (C1) about said rotation axis (A), and a pair of first nozzles (23b) arranged in tandem at a radial distance from the assembly portion (21) so that each of them respectively traces in use a second (C2) and a third (C3) circumference about said rotation axis (A).

8. A device (1) according to claim 7, characterized in that a second longitudinal portion (28) of the arm (20), opposite to the first, carries: one said first nozzle (23b) arranged at a radial distance from the assembly portion (21) so that this traces in use a fourth circumference (C4) about said rotation axis (A); one said second nozzle (23c) arranged at a radial distance from the assembly portion (21) so that this traces in use said second circumference (C2) about said rotation axis; and one said first nozzle (23b) arranged at a radial distance from the assembly portion (21) so that this traces in use said third circumference (C3) about said rotation axis (A).

9. A device (1) according to claim 8, characterized in that said fourth circumference (C4) has a radius (R4) greater than that (R1) of said first circumference (C1) and smaller than the radius (R2) of said second circumference (C2).

10. A device (1) according to any preceding claim, characterized in that said arm (20) is provided with reaction thrust generating means (30; 23) to determine in use the rotation about said axis (A).

11. An electric household appliance (2), in particular a front-loading dishwashing machine, comprising a washing chamber (3) accommodating at least one container basket (4) of the dishes (5) to be washed, and delivering means (7) of a pressurized service fluid (8), e.g. a washing and/or rinsing fluid, towards an inlet head (10) arranged in the washing chamber (3) and having a symmetry axis (A) thereof arranged in the washing chamber in an essentially vertical position, characterized in that it comprises a device (1) according to any claim from 1 to 10, wherein said arm (20) is idly and fluid-tightly mounted on said inlet head (10) with a central assembly portion (21) thereof, preferably immediately either over or under said basket (4).

Drawing