GB2313299A

GB2313299A - Rotary spray assembly for dishwasher

Info

Publication number: GB2313299A
Application number: GB9710162A
Authority: GB
Inventors: Ugo Favret
Original assignee: Electrolux Zanussi Elettrodomestici SpA
Current assignee: Electrolux Zanussi Elettrodomestici SpA
Priority date: 1996-05-22
Filing date: 1997-05-19
Publication date: 1997-11-26
Anticipated expiration: 2017-05-19
Also published as: ES1037337U; ES1037337Y; GB2313299B; FR2748927B3; FR2748927A1; GB9710162D0; ITPN960022U1; ITPN960022V0; IT241555Y1; DE29708597U1

Abstract

A dishwashing machine with at least one rotary assembly (5) provided with sprayers (10) for spraying jets of washing liquid under pressure on to the articles which are loaded with the washing tub on to at least one basket. The rotary assembly (5) comprises, on a tubular projection (15), a pair of oppositely disposed nozzles (21,22) which can be fed selectively by switchable means (25,35) with the same liquid under pressure. The nozzles generate thrust jets (23,24) which cause rotary movement of the rotary assembly (5) in the two directions. According to the invention the switchable means (25,35) are actuated by colliding with a bilateral engagement device (30,40) fixed to a stationary part of the machine, for example the bottom (31) of the washing tub. The switchable means can be a flap valve (25, fig 3), having a crank projecting from its spindle which collides with the device (30), or a ball valve (35, fig 6).

Description

IMPROVEMENTS IN DISHWASHING MACHINES WITH AT LEAST ONE ROTARY SPRAY ASSEMBLY The present invention relates to a dishwashing machine comprising a washing tub with at least one basket and at least one rotary assembly provided with sprayers for spraying jets of liquid which is fed under pressure onto the articles to be washed which are loaded on to the basket and at least one pair of nozzles with substantially horizontal axes which can be fed selectively with the same liquid by switchable means in such a way as to emit alternate thrust jets which cause the rotary movement of the rotary assembly in both directions in a substantially horizontal plane.

The effectiveness of the operations for washing the crockery is largely governed by the mechanical action of the fets of liquid which are sprayed by the sprayers of the rotary assembly. In order not to leave points 'in shadow', that is to say poorly sprayed by the jets, it is known to reverse periodically the direction of rotation of the rotary assembly during the washing operation.

The document US-A-3,797,509 provides for the use of bistable hydraulic valve for selectively supplying washing liquid under pressure to two nozzles which are disposed on the rotary assembly with the axes perpendicular, in such way as to produce periodic alternation of the direction of rotation. Switching of the valve is effected by virtue of programmed pauses in operation of the pump for recirculation of the washing liquid. Because of the increased complexity required in regard to the programmer that machine suffers from the disadvantages due to repeated starting and stopping of the pump in terms of level of noise and reliability.

The document GB-A-2,290,223 proposes generating a hydraulic thrust jet by means of at least one nozzle provided on a rotor pivoted on the rotary assembly in a displaced position with respect to the axis of rotation of the latter, which, during all the washing cycles, periodically reverses the direction of rotation of the rotary assembly, more precisely after the rotary assembly has completed at least one complete revolution about its axis. That construction is undoubtedly efficient but, by virtue of the strict dimensional tolerances of the nozzle and the rotor, it is rather expensive and rather unsuitable to being adopted on more economical dishwashing models.

The aim of the present invention is to provide a dishwashing machine having a high level of washing efficiency but of particularly simple and reliable construction, without the above-mentioned disadvantages due to periodic starting and stopping of operation of the recirculating pump and the associated actuating motor.

According to the present invention there is provided a dishwashing machine comprising a washing tub with at least one basket and at least one rotary assembly with a substantially vertical axis which is provided with sprayers for spraying jets of liquid supplied, in use, under pressure on to the articles to be washed which are loaded on said basket and provided with at least one pair of nozzles with substantially horizontal axes which can be selectively fed with the liquid by switchable means in such a way as to emit alternate thrust jets which cause rotary movement in the two directions of the rotary assembly wherein, said switchable means are actuated by colliding with a stationary bilateral engagement device.

In order clearly to show features and advantages of the invention, two embodiments thereof by way of example will be described herein after, as shown in the accompanying drawings in which: Figure 1 shows a simplified partial section of a dishwashing machine in accordance with a first embodiment of the invention; Figures 2, 3 and 4 are views in vertical section of the rotary assembly of the dishwashing machine of Figure 1 in three different angular positions during the rotary movement thereof; and Figures 5, 6 and 7 are respectively similar to Figures 2, 3 and 4 but relate to a second embodiment of the invention.

Conventionally the dishwashing machine of Figure 1 comprises, enclosed in an external casing 1, a washing tub 2 with baskets 3,4 for loading the articles to be washed (not shown). Associated with the baskets 3,4 are respective rotary assemblies having two arms 5,6 which, by way of vertical tubes 7 and 8, are supplied with washing liquid under pressure by a recirculation pump (not shown), the pump taking in the liquid from the bottom well 9 in the lowest region of the washing tub 2. The rotary assemblies 5 and 6 are mounted freely rotatably on the respective tubes 7 and 8 whereby they can rotate in a substantially horizontal plane.

The rotary assemblies 5 and 6 are also provided, on their upward surfaces 12 and 13, with sprayers 10 and 11 for spraying jets of washing liquid under pressure on to the articles loaded on the baskets 3 and 4.

In accordance with the invention, extending from its lower surface 14 which is the surface opposite to the surface 12 at which the sprayers 10 are disposed, the lower rotary assembly 5 is provided with a vertical tubular projection 15. The jets sprayed by the sprayers 10 give rise to a substantially zero reaction torque in the plane of rotation of the rotary assembly 5. The tubular projection 15 of rectangular section has its upper end 16 open and thus communicating with the interior 17 of the rotary assembly 5 and it is provided, adjacent its closed bottom 18 and on oppositely disposed walls 19,20 with two nozzles 21,22 having their axes substantially horizontal. As will be described in greater detail hereinafter, the nozzles 21 and 22 are capable of selectively generating oppositely directed hydraulic thrust jets 23 and 24 which cause the rotary movement of the rotary assembly 5 in the two directions.

In the embodiment shown in Figures 2, 3 and 4, accommodated in the interior of the projection 15 are switchable means for the selective supply to the nozzles 21,22 of washing liquid under pressure. In accordance with the invention, the switchable means are formed by a flap valve 25 with a blade or flap 26 which extends over substantially the entire inside width of the tubular projection 15 to a crank 28 and thus a projection 29 which is substantially parallel to the pivot pin 27. The invention includes a stationary engagement device 30 which is fixed to the bottom surface 31 of the washing tub 2 and which extends upwardly until it goes beyond the vertical position of the projection 29. Desirably the engagement device 30 is bilateral insofar as it is of a flat shape with two oppositely disposed faces 32 and 33, as can be seen in Figures 3 and 4.

The mode of operation of this first embodiment of the invention is as follows. At the beginning of the washing program when the recirculation pump of the machine begins to feed the rotary assemblies 5,6 with the washing liquid the above-mentioned switchable means are in any angular position for example the position shown in Figure 2 in which the flap 26 of the flap valve 25 bears against the wall 19 of the tubular projection 15. The flap 26 diverts the flow of liquid under pressure which passes into the tubular projection 15 by way of the upper opening 16 into the nozzle 22, thus producing a thrust jet 23 which, by virtue of the reaction effect, causes the rotary assembly 5 to rotate in the direction of the arrow F1. That rotation continues until the moment that the rotary assembly is in the position shown in Figure 3 whereby the projection 29 of the flap valve 25, colliding against the face 33 of the engagement device 30, is angularly displaced in the clockwise direction as indicated by the arrow R1 in Figure 3, entraining the crank 28 with it.

The flap 26 of the valve 25 thus switches its position, coming into contact with the opposite wall 20 of the tubular projection 15. In that way the flow of liquid under pressure is diverted from the nozzle 22 to the oppositely disposed nozzle 21 so as to spray the thrust jet 24 which, by a reaction effect, causes the rotary assembly 5 to rotate in the direction of the arrow F2 opposite to the previous direction F1. The rotary movement in the direction F2 continues through about 360 , that is to say to the moment at which the rotary assembly 5 is in the position shown in Figure 4 in which the projection 29 of the flap valve 25 collides with the face 32 of the engagement device 30, entraining with it the crank 28 which is angularly displaced in the anti-clockwise direction, that is to say as indicated by the arrow R2 in Figure 4. The flap 26 of the valve 25 again switches in position, coming back into contact with the wall 19 of the tubular projection 15 whereby the flow of liquid under pressure is diverted from the nozzle 21 to the nozzle 22 which thus sprays the thrust jet 23 which, by the reaction effect, causes the rotary assembly 5 to rotate in the direction F1.

Those alternate rotary movements, of an amplitude that is practically equal to 360 , are repeated for the entire duration of the washing procedure but without having recourse to starting and stopping the recirculation pump and therefore without the above-mentioned disadvantages.

The embodiment of the invention shown in Figures 5, 6 and 7 differs from the first embodiment by virtue of the following structural details: - the switching means for the hydraulic thrust jets 23,24 is provided as a valve with a bistable ball 35 capable of moving on the shaped closed bottom 36 of the projection 15 between two seats 37,38 in such a way as alternately to close the two coaxial, oppositely disposed nozzles 21 and 22; - the stationary bilateral engagement device 40 is provided on its faces 41,42 with two projections 43,44 of a shape and dimensions such as to be able to penetrate through the nozzles 21,22, causing closure thereof. Such penetration movements alternately displace the ball of the bistable valve 35 between the seats 37,38 in the direction of the arrows R1 (Figure 6) and R2 (Figure 7) so as alternately to produce the thrust jets 23,24 from the nozzles 21 and 22 and thus the alternate rotary movements of the rotary assembly 5 in the directions of the arrows F1 and F2 in ways and with effects which are the same as those described hereinbefore in relation to the first embodiment of the invention.

The advantages of the invention can be summarised as involving notable structural simplicity and consequently very low cost, a high level of reliability in operation and the total absence of adverse side effects due to the recirculation pump being repeatedly started and stopped.

Finally it will be appreciated that the man skilled in the art may derive further embodiments and alternative configurations of the invention which are also protected by the present patent. In particular it is possible to mount a tubular projection with oppositely disposed nozzles for generating the thrust jets also (or only) on the upper rotary assembly 6 rather than on the lower rotary assembly 5 as described herein before. In that case the associated engagement device can be fixed at a position corresponding to the crockery-carrying basket 4 which, during operation of the machine, constitutes a stationary part thereof.

Claims

CLAIMS 1. A dishwashing machine comprising a washing tub with at least one basket and at least one rotary assembly with a substantially vertical axis which is provided with sprayers for spraying jets of liquid supplied, in use, under pressure on to the articles to be washed which are loaded on said basket and provided with at least one pair of nozzles with substantially horizontal axes which can be selectively fed with the liquid by switchable means in such a way as to emit alternate thrust jets which cause rotary movement in the two directions of the rotary assembly wherein, said switchable means are actuated by colliding with a stationary bilateral engagement device.
2. A dishwashing machine according to claim 1 wherein, said engagement device has a flat body with two oppositely disposed faces.
3. A dishwashing machine according to claim 1 or claim 2 wherein, said nozzles are disposed in opposite relationship and with their axes parallel on a substantially vertical tubular projection which extends from a horizontal surface opposite to the surface on which said sprayers are disposed, and further wherein, said switchable means are also provided within the tubular projection.
4. A dishwashing machine according to claim 2 wherein, said switchable means are formed by a flap valve with a pivot pin and a flap, said pivot pin being supported in the interior of said tubular projection in such a way that said nozzles are disposed on opposite sides of the flap accommodated in the interior thereof, the flap valve further being provided on the outside of said tubular projection with a crank which is fixed with respect to the pivot pin and terminates with a rigid projection extending substantially parallel to the pivot pin and capable of alternately colliding with said two oppositely disposed faces of the stationary engagement device.
5. A dishwashing machine according to any one of the preceding claims wherein, said stationary engagement device is fixed with respect to a wall of the washing tub preferably to the bottom thereof.
6. A dishwashing machine according to any one of claims 1 to 3, wherein, said stationary engagement device is supported by the basket on which the articles sprayed by the rotary assembly are located.
7. A dishwashing machine according to any one of the preceding claims wherein, the axes of the jets of liquid sprayed by the sprayers of at least the rotary assembly provided with said switchable means involve an angulation such as not to produce any reaction effect which causes rotary movement thereof.
8. A dishwashing machine according to claim 1 wherein, said switchable means are formed by a bistable valve with a ball accommodated in the interior of said tubular projection and capable of moving between the two seats thereof due to the effect of colliding with substantially horizontal projections which are provided on the opposite faces of said stationary engagement device and which are capable of penetrating into the interior of the tubular projection in such a way as alternately to displace the ball of said valve from one of its two seats to the other.
9. A dishwashing machine constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4 or Figures 5 to 7 of the accompanying drawings