EP1101435B1

EP1101435B1 - Device for intercepting the flow of a fluid, in particular for washing machines

Info

Publication number: EP1101435B1
Application number: EP00124811A
Authority: EP
Inventors: Giovanni Perucca; Paolo Savini; Stefano Belfiore
Original assignee: Eltek SpA
Current assignee: Eltek SpA
Priority date: 1999-11-16
Filing date: 2000-11-14
Publication date: 2009-04-01
Anticipated expiration: 2020-11-14
Also published as: ATE427065T1; DE60041905D1; ES2325051T3; EP1101435A2; ITTO990997A1; ITTO990997A0; EP1101435A3; IT1311444B1

Abstract

A device is described, for intercepting the flow of a fluid that passes through a distributing circuit (4,6), in particular of a washing machine, where the said device (10) comprises an actuator (15) presenting a displacement organ (15A) capable of working in two opposite directions, said displacement organ (15A) being able to move a movable shutter member (14) until the latter reaches at least a first working position, striker means (AP,AP') that follow the movement of said shutter member (14) and capable of coming into contact with respective fixed stopping surfaces (18A,18B), the contact of said striker means (AP,AP') with a first of said stopping surfaces (18A,18B) corresponding to the attainment by said shutter member (14) of said first working position. According to the invention, under constancy of power supply to said actuator (15), the latter is capable of automatically inverting the direction of movement of said displacement organ (15A), as a result of the effect, in particular the mechanical effect, that the contact of said striker means (AP,AP') with one of said stopping surfaces (18A,18B) determines on said displacement organ (15A). <IMAGE>

Description

The present invention refers to a device for intercepting the flow of a fluid that passes through a distributing circuit, in particular for washing machines.
As known, in the field of washing machines, the use of flow diverting or intercepting devices applied to dishwashers has a particular importance.
Usually, dishwashers for household usage comprise a box-shaped structure defining a washing chamber that houses an upper loading basket and a lower loading basket, being intended for containing the items to be washed. A sprayer is positioned under each loading basket which, by rotating around a substantially vertical axis, hits the dishes placed in the basket with a plurality of washing liquid jets; to this purpose, a special motor-driven recirculation pump conveys the liquid under pressure to the sprayers.
In some known applications, especially aimed at reducing water consumption, the hydraulic circuit of the dishwasher is obtained in such a way to execute a washing cycle by feeding a single sprayer, or by feeding both sprayers alternately.
The first solution is typical of cases in which the dishwasher must be able to carry out a so-called "reduced" washing program, i.e. when only one of the basket is used to contain the dishes, and only the sprayer that corresponds to the used basket must be fed with the washing liquid.
The second solution mentioned above, concerning the alternate feeding of the sprayers, is spreading currently in dishwashers and its aim is substantially to:

allow for the use a single recirculation pump, for both sprayers, whose electric motor has relatively small dimensions; it is clew that, on this score, should the same pump feed at the same time two sprayers, it must have a more powerful and hence bigger motor;
reduce the operating noise of the machine, being determined by the impact against the walls of the washing chamber of the liquid jets streaming through the sprayers;
allow for a certain saving in water consumption.

In general, in the first case mentioned previously, a device can be provided for a continuous interception of the liquid flow coming from the recirculation pump to one of the two feeding branches of the sprayers; the intercepting device, being duly controlled by the machine control system, keeps one of the two branches of the hydraulic circuit closed, in such a way as to feed with the liquid, throughout the washing program, only the sprayer related to the used basket.
In the second case mentioned above, an intercepting device is instead provided for directing alternately the liquid in one of the two branches mentioned above; in other words, the control system of the machine controls the intercepting device in such a way that the latter opens and closes alternately the two branches of the hydraulic circuit, in such a way that the washing cycle is obtained by feeding alternately the upper and lower sprayer.
It should be noticed that, in some solutions, a same intercepting device can execute both of the above-mentioned functions, i.e. continuous closing on one of the two circuit branches, in order to carry out a "reduced" washing program, and flow deviation in the two branches, in order to carry out a washing with alternate feeding of the sprayers.
In general, an intercepting device used to obtain an alternate washing comprises substantially a movable flap or plug, placed in correspondence of the point where the two above-mentioned branches of the hydraulic circuit depart; said plug can assume at least a first operating condition, characterised by the opening of the branch that feeds the upper sprayer and by the closing of the branch that feeds the lower sprayer, and a second operating condition, opposed to the previous one.
In some cases, the movement of the above-mentioned plug from one position to the other is obtained by means of a electric-thermal actuator.
The actuators of the thermal type are well known and do not need an in-depth description here (see for example EP-A-940 577 ). It is enough to specify here that these actuators comprise usually a body containing a thermoexpansible material and, at least partially, a piston; a heater is associated to the mentioned body, like a resistor with a positive temperature coefficient, or PTC.
The heating of the actuator's body, induced by the resistor, determines a volume expansion of the expandable material, and the resulting exit movement of the piston, whose thrust is used to move the plug of the flow diverting device from the first to the second operating condition. Later, when the electric supply to the resistor is interrupted, the temperature of the actuator's body decreases, with the ensuing volume contraction of the thermoexpansible material; the piston can therefore retract towards the inside of the body, upon the action of an elastic element, like a spring, and in this way switch back the plug of the flow intercepting device from the second to the first operating condition.
Therefore, as it can be imagined, through a series of repeated activations and deactivations of the actuator's heater, it is possible to feed the washing liquid alternately to the two sprayers.
For example in EP 0 705 561 in the name of CANDY SPA is disclosed a device for controlling a valve device which regulates a flow of washing liquid and which is placed between means for pumping the washing liquid and two feed pipes of two respective spraying rotors of a dishwasher, for the selective feeding of said rotors, which comprises means for selecting the working condition of said valve device, housed in a control Panel of the dishwasher and operatively connected to said valve device by mechanical transmission means.
Another example of a known device is described in DE3904359 in the name of LICENTIA GMBH which discloses a changeover device for a dishwashing machine having a common inlet connection and separate outlet connections, via which spray devices can be connected in terms of flow in a variable sequence to a circulation pump; for this purpose, the changeover device has a multi-way valve in the form of a multiple rotary disc valve which has at least two perforated discs adjustable independently of one another in a common housing; the perforated discs have main and secondary passages of different configuration and can be turned relative to one another so that main and secondary passages in different combinations move into a mutual covering arrangement and into alignment with at least one of the outlet connections.
Although the technique described above is reliable on the average, it presents some drawbacks.
The first drawback derives from the fact that the control system of the dishwasher, whether electromechanical or electronic, presumes a certain complexity to obtain the required feeding cycles of the thermoactuator.
Another drawback of the mentioned solution derives from the fact that the operating times of a thermal actuator are relatively long, since the movements obtained from it are linked to the heating and cooling phenomena of a thermoexpansible material. A drawback connected to the previous one consists of the fact that the operating times of a thermal actuator are different in the two operating stages; in other words, the time required to produce the heating of the thermoexpansible material and the ensuing exit movement of the piston from the actuator's body is different from the time required to obtain the cooling of the same material, and the ensuing backing of the piston.
It follows that the opening times of the two different branches of the dishwasher's hydraulic circuit can be different.
In other known solutions, in order to obtain the desired movement of the plug or shutter of the intercepting device, a double winding motor is provided, instead of a thermal actuator.
In this case, the motor is initially operated with a first direction of rotation, by energising its first winding, to move the shutter from its first to its second working position; then, the direction of rotation of the motor is inverted, energising its second winding, in order to return the shutter to its initial position.
In the simplest solutions, the supply of the mentioned double winding is time-controlled, i.e. it is supplied for a fixed period being considered sufficient to determine the passage of the shutter from one working position to the other.
However, as time goes by, the calibration or adjustment of the diverting device can be compromised; for example, this is due to the fact that some plastic parts of the intercepting device are exposed to continuous thermal stresses, and hence potentially subject to variations in size. In these circumstances, the time set for the motor supply may result longer or shorter of the one strictly required to obtain a correct positioning of the shutter, with ensuing operating extrastrokes or efforts, which can break the intercepting device or cause the failure of its motor, or make it impossible to reach the correct working position of the shutter.
In most sophisticated solutions, special sensors like microswitches are provided, apt to detect that the shutter has reached the proper working position; at this point, the control system of the machine controls the inversion of the direction of rotation of the motor, until the attainment of the new working position is detected, and so on throughout the "reduced" washing cycle.
Although the solution mentioned above is reliable on the average, it assumes however the use of a relatively expensive motor, as it is expensive and complex the system for controlling the supply and the direction of rotation of such a motor.
The present invention has the aim of solving the above drawbacks of the prior art.
Within this frame, the aim of the invention is to indicate a device for intercepting the flow of a fluid, in particular for washing machines, being of simple design and manufacturing, being highly reliable in time and being of low cost.
These and other aims are achieved, according to the present invention, by a device for intercepting the flow of a fluid, in particular for a washing machine, having the characteristics of the annexed claims, which form an integral part of the present description.
Further aims, features and advantages of the present invention will become apparent from the following detailed description and the annexed drawings, which are supplied by way of non limiting example, wherein:

Fig. 1 shows a schematic section of a dishwasher that uses a liquid flow intercepting device according to the present invention;
Fig. 2 represents a plan view of the intercepting device of the dishwasher of Fig. 1;
Fig. 3 represents a side view of the intercepting device of Fig. 2;
Fig. 4 represents a first exploded view of.some components of the intercepting device of Fig. 2 and 3;
Figs. 5 and 6 represent a second and third exploded view of some components of the intercepting device of Fig. 2 and 3, according to two different angles;
Figs. 7 and 8 represent sections of the intercepting device according to the invention, by axis B-B and axis C-C respectively of Fig. 3, in a first working position;
Figs. 9 and 10 represent sections of the intercepting device according to the invention, by axis B-B and axis C-C respectively of Fig. 3, in a second working position.

Fig. 1 shows a schematic representation of a dishwasher using an intercepting device obtained according to the principles of the present invention.
In this figure, 1 indicates the washing chamber of the machine, comprising a lower collecting sump, indicated with 2; 3 indicates a washing or recirculation pump, equipped with an electric motor.
3A indicates the suction branch of the mentioned pump, that draws the washing liquid from the sump 2; pump 3, by means of its delivery 3B, forces the washing liquid in a hydraulic circuit, comprising a first branch 4 feeding a lower sprayer 5, and a second branch 6 feeding an upper sprayer 7; baskets 8 and 9 are placed in a known way above of each sprayer.
10 indicates a device for intercepting a flow of liquid, placed between the inlets of the two branches 4 and 6, which is properly controlled by the machine's control system, as it will be clear later.
The intercepting device 10 is capable of assuming at least two different alternative operating conditions, and in particular:

a closing condition of branch 4, represented in Fig. 1, with opening of branch 6 at the same time;
a closing condition of branch 6, with opening of branch 4 at the same time.

The intercepting device 10, which is shown in different views in Figs. 2 and 3, comprises a main body 11, for example realised in thermoplastic material, defining an inlet 12 for the connection to the delivery 3B of pump 3, and two outlets 13A and 13B for the connection to the feeding branches 4 and 6 respectively, of the lower sprayer 5 and the upper sprayer 7; the body 11 comprises an upper part 11A and a lower part 11B, coupled with known means, with a gasket placed in between, not represented in the figures.
Inside the body 11, a plug or shutter member 14 is placed between inlet 12 and outlets 13A and 13B; in the example, this plug is of the rotating or angular movable type.
An electric motor 15 is associated to the upper part of body 11, by means of screws 16 intended for being screwed in suitable seats 17 defined in the body 11.
Motor 15, which, if necessary, is equipped with a suitable internal gear-reducer, presents a shaft 15A that is connected to a suitable transmission element ET, made integral with plug 14 or realised as a single piece with the latter; obviously, on the upper part of body 11 a proper opening is defined, for the passage of a part of the transmission element ET, in correspondence of which proper sealing means are preferably provided.
AP indicates an additional member, coupled with the transmission element ET, presenting a radial projection AP'; 18A and 18B indicate two stops with which projection AP' is able to come into contact following an angular movement of the transmission element ET (see, to this purpose, also Figs. 7 and 9). It should be noticed that, in the given example, the above-mentioned stops 18A and 18B consist of projections of the upper part 11A of body 11, which are used also as supporting and positioning means for the motor 15.
In Figs. 4-6 some components of the intercepting device 10 according to the invention are represented in more detail.
In these figures notice the particular shape of plug 14, which is defined as a whole by an upper circular wall 14A and a lower circular wall 14B, joined together by means of a bent wall 14C extending for nearly half of the circumference of the said walls 14A and 14B; in other words, therefore, the plug 14 has substantially the shape of a hollow cylinder whose circumference wall lacks a portion. However, it is clear that, in the practical actuation of the invention, the shape of the plug 14 may differ from the one in the example of the figure, like for example a substantially spherical shape, where a passage or a discharge having a proper shape is defined in order to allow the required hydraulic connection between the inlet 12 and the outlet 13A, and between the inlet 12 and the outlet 13B.
It should be noticed that, in the given example, discharges or undercuts having substantially a semicircular shape are defined at the two side ends of the bent wall 14C, indicated with 14D, with dimensions being congruent to that of the outlets 13A and 13B of the device 10.
The transmission element ET is coupled to the upper wall 14A of the plug 14, or realised as single piece with the latter; in the lower part of the transmission element ET, i.e. the one that remains within body 11 of the intercepting device 10, are defined one or more seats ET', for the housing of an equal number of proper sealing means, like one or more o-rings, not represented.
The upper part of the driving element ET, i.e. the one remaining outside the body 11 of the intercepting device 10, is indicated in Figs. 4-6 with ET"; at the upper end of part ET", on its external surface, a discharge or undercut 19 is defined, whose function will be explained later; part ET" is internally hollow, for defining a seat 20 able to receive the end of shaft 15A of motor 15.
The end portion of shaft 15A and seat 20 present congruent sections, so that the angular movement of the shaft determines a corresponding movement of the transmission element ET; for this purpose, in the example of the figure, the end of shaft 15A and seat 20 present a substantially semicircular section, or an or equivalent one; on the other hand, it is clear that such a section can have any other shape proper for the object, like for example a square or hexagonal shape.
The additional member AP presents a housing (not visible in the figures) in its lower part, being able to receive and couple with the upper end of part ET" of the or transmission element ET, where the mentioned discharge or undercut 19 is defined.
Also in this case, therefore, the upper end of part ET" and the mentioned housing of the member AP are designed in such a way that the angular movement of the transmission element ET determines a corresponding movement of the member AP and of the relative radial projection AP'.
Anyway, in order to ensure further that to the angular movement of the driving element ET, and so of plug 14, corresponds an equivalent movement of the projection AP', the central passage of member AP, indicated with 21, can advantageously present a section congruent to that of seat 20 and to the end portion of shaft 15A (as said, in. the example of Fig. 4, this section has a substantially semicircular shape).
However, notice that the coupling between shaft 15A, member AP and element ET can be obtained with any known technique.
According to the present invention, motor 15 is a single-phase synchronous motor, having a single winding and a permanent magnet rotor.
As known, this kind of motor has no preferred starting direction, i.e. its rotor is able to start and rotate in both directions (clockwise and counter-clockwise) indifferently. It also known that, if during the angular movement in one direction, the rotor is subject to a braking moment or is exposed to a thrust in the opposite direction, the mentioned type of motor reaches a stall condition, which is automatically followed by a reversal of the direction of angular movement of the rotor, due to electromagnetic effect. It is also known that the rotor or the shaft of the mentioned type of motors has a substantially fixed revolution speed, which depends on the mains frequency, on the motor's specifications (for example the number of poles) and on the possible presence of a gear reducer.
Therefore, according to the invention, in order to invert the direction of rotation of motor 15, and of shaft 15A, the stops 18A and 18B are provided, with which projection AP' comes into contact alternately, according to the direction of clockwise or counter-clockwise rotation of the motor; as it can be imagined, in this way, plug 14 can be moved by the transmission element 14A in opposite directions, in order to open and close alternately, and with equal times, the outlets 13A and 13B of the intercepting device 11.
Finally, it should be noticed that, preferably, the end of projection AP' intended to come into contact with the stops 18A and 18B is equipped with elastic elements, such as a rubber covering, in order to create a bouncing effect, i.e. for contributing to give projection AP', as well as element ET and shaft 15A, an angular movement having a direction being opposite to that of impact on one of the stops.
Obviously, for this reason, the elastic elements can be provided on stops 18A and 18B, instead of on projection AP', or the same projection AP' can be shaped for giving the latter a certain elasticity that is useful for the purpose.
The dishwasher equipped with the intercepting device according to the present invention works as follows.
After loading the dishes in the baskets 8 and 9, the user selects the desired washing cycle and starts the machine; the washing cycle described later provides for this reason the alternate supply of the sprayers.
Therefore, the control system of the machine controls the execution of the washing cycle, including its usual phases, like for example one or more prewash phases, one or more washing phases, one or more rinsing phases, according to the technique of supply alternation the sprayers.
In general, each phase of the cycle starts by loading in tank 1 the required water quantity, measured with known modalities (for example by means of a pressure switch). Therefore, once the quantity of water required by the first prewash phase has been loaded from the external water mains, the control system controls the activation of the recirculation pump 3 by supplying the motor of the latter.
In parallel with the activation of pump 3, the control system of the machine enables the supply of motor 15 of the intercepting device 10. Motor 15 therefore starts turning in one direction, and so moves plug 14, for example towards the closing position of outlet 13A and simultaneous opening of outlet 13B of the intercepting device 10; this situation is shown in Fig. 8.
When plug 14 reaches this position, projection AP' reaches stop 18A, as shown in Fig. 7; the mechanical effect deriving from the contact between projection AP' and stop 18A is that the transmission element ET, as well as shaft 15A of motor 15, are subject to a braking and/or bouncing action as defined above; motor 15 reaches a stall condition and changes its direction of rotation.
This means that motor 15 starts turning in a second direction, being opposite to the previous one, and so moves plug 14 towards the closing position of outlet 13B and simultaneous opening of outlet 13A of the intercepting device 10; this situation is shown in Fig. 9.
In this case, when plug 14 reaches this position, projection AP' reaches stop 18B (as shown in Fig. 8); also in this case, the mechanical (i.e. braking and/or bouncing) effect that the contact between projection AP' and stop 18B determines on the driving element ET and on shaft 15A causes motor 15 to reach a stall condition, and the new subsequent reversal of its direction of rotation.
This operation of motor 15 and of the intercepting device 10 continues throughout the relative phase of the washing cycle, and preferably throughout the activation of pump 3; said phase then ends by discharging the washing water from tank 1 by means of a suitable pump, not represented in Fig. 1.
The above is followed a new supply of water in the tank, in order to carry out the following phase, which is executed in the same way as the one described previously, and so on for all the other phases of the washing cycle.
As said, motor 15 has no preferred starting direction, but as it can be imagined, this is practically irrelevant in view of the proper and efficient operation of the dishwasher; the position of plug 14 before starting motor 15 is practically irrelevant, too.
The alternate feeding of the sprayers is obtained as described above.
During manufacturing, the motor 15 will be realised with known modalities in order to obtain a proper speed of shaft 15A, which determines the desired switching speed of plug 14 from one working position to the other; these speed values depend on the mains frequency as well as on the motor specifications (for example, on the number of its poles) and/or on the possible presence of a gear reducer; for what concerns this aspect, it should be pointed out that the prevision of a proper gear reducer realised as known, seems to be preferable, in order to have a small motor 15, whose shaft 15A is anyway able to produce high forces or torques, being adequate to the purpose.
Advantageously, motor 15 can be connected electrically in parallel with respect to the motor of pump 3, in such a way as to ensure a simultaneous supply, and therefore a simultaneous operation of device 10 and of the said pump 3.
From the above description the features of the present invention are clear.
In particular, an intercepting device has been described, for a flow of a fluid that passes through a distributing circuit (branches 4 and 6), in particular of a washing machine; the device (10) comprises an actuator (motor 15) presenting a displacement part (shaft 15A) that can work in two opposite directions, said displacement part being able to displace a plug (14) which can move until it reaches at least a respective first working position.
The intercepting device (10) comprises striker means (member AP and corresponding radial projection AP') that follow the movement of plug (14) and are capable of coming into contact with respective fixed stopping surfaces (stops 18A and 18B), where the contact of the strikers with a first of the stopping surfaces corresponds to the attainment, by plug (14), of the said first working position.
According to the invention, under constancy of electric supply to the actuator (15), the latter is capable of inverting the direction of movement of the displacement part (15A) automatically, following the effect (in particular a mechanical one) that the contact of the striker means (AP,AP') with one of the stopping surfaces (18A,18B) determines on the displacement part (15A).
The plug (14) is capable of reaching at least a second working position, where the contact of the striker means (AP,AP') with a second one of the stopping surfaces corresponds to the attainment, by plug (14), of said second working position. In this way, following the automatic reversal of the direction of movement of the displacement part (15A) determined by the contact of the striker means (AP,AP') with the stopping surfaces (18A,18B), the plug (14) is continuously moved in opposite directions, in order to pass in an alternate way between the said first and the said second working position.
In the preferred embodiment by the invention, the actuator comprises at least one single-phase synchronous motor, in particular having a single winding and a permanent magnet rotor, and the speed of the displacement part is determined by the mains frequency and/or by a gear reducer.
The invention has a specially advantageous application in the field of dishwashers, for the realisation of washing cycles with alternate supply of the sprayers; however, it is clear that the described device can be applied also on other kinds of washing machines for household usage, like for example laundry washers and/or washer-dryers, and on other devices and systems where it is useful or necessary to realise a cyclical deviation or interruption of the flow of a fluid, whether liquid or aeriform.
Moreover, it should be pointed out that the device according to the invention must not be perceived as applicable exclusively to cases in which a first duct must be completely closed in favour of another one, but can be provided instead for partializing or adjust the flow-rate of the fluid which has to be cyclically fed to the two ducts.
Within this frame, the shape of plug 14 and the two end-of-stoke positions of the latter can be chosen in order to obtain only a suitable narrowing or throttling of the distributing circuit, between the inlet 12 and the outlet 13A on one side, and between the inlet 12 and the outlet 13B on the other side.
This variant can be applied when the two branches of the distributing circuit of the fluid that depart from the outlets of the device according to the invention must be fed substantially in an alternate way with different liquid flow rates, for example in order to obtain a wash with different washing pressures for sprayers 5 and 7, if the dishes contained in basket 9 are more fragile than those in basket 5.
Within this frame, the terms "intercepting device" and "plug member" used here must be intended in their more general meaning, i.e. indicating respectively a device that allows also the partial closure of a duct, and a member that allows to adjust the flow rate of a fluid.
For what concerns the application mentioned just now, it should also be pointed out the possibility of changing the realisation of the stops 18A and 18B, in order to allow for the adjustment of their position with respect to the shaft 15A or the projection AP'; for example, in the simplest embodiment, each stop can consist of the end of a threaded element, being screwed in a respective seat that extends substantially perpendicularly to the shaft 15, said seat being defined in a proper support that raises from the upper surface of body 11.
In this way, therefore, by screwing more or less the above-mentioned threaded elements in their seat, it is possible to adjust or vary the position of the stop points of projection AP', i.e. of its end-of-stroke points in the two opposite directions of movement, with the ensuing possibility of changing the two working positions of plug 14 and adjusting the flow-rate of fluid to be fed at outlet 13A and 13B of the device 10.
From the above description the advantages of the present invention are also clear.
After carrying out exhaustive practical tests, the device for intercepting the flow of a fluid according to the present invention resulted in resolving efficiently the previously mentioned typical problems of the prior art. In particular,

the control system of the intercepting device 10, and therefore of the apparatus comprising it, is not complicated; the control of motor 15 is obtained simply, through a constant electric supply of the same, which in the case of dishwashers is obtained preferably together with the activation of the recirculation pump 3;
the operating times of the intercepting device 10 are practically fixed and the duration of the alternate opening/closing phases of branches 4 and 6 of the hydraulic circuit of the machine is always the same;
the motor 15 of the intercepting device 10 is simple and cheap, since it does not need a double winding for allowing the controlled reversal of its direction of rotation, and is of a common and reliable type;
thanks to the intrinsic characteristics of the motor 15, possible accidental changes in the calibration or adjustment of the intercepting device 10 are irrelevant for the purpose of the proper operation of the latter, without extra-stroke risks or operating efforts being typical of the prior art;
in order to control the supply and the direction of rotation of motor 15, the intercepting device 10 does not require sensors for the detection of both working positions of the plug 14.

It is obvious that many. changes are possible for the man skilled in the art to the intercepting device described as an example, without departing from the inventive idea.
For example, the possibility is mentioned of providing a single sensor for the intercepting device 10, in order to detect the attainment of one of the two working position of the plug 14; this variant, which remains in any case advantageous with respect to the prior art mentioned previously, can prove to be useful when it is desired to assign to the switching device 10 also the function of continuous closing of one of the two branches 4 and 6 of the supply circuit of sprayers 5 and 7, in order to obtain a "reduced" washing programme, i.e. obtained by using only one of the basket 8 and 9.
For example, a magnetic element can be associated to projection AP' and a proper known position switch or sensor (for example a reed sensor or a Hall effect sensor) can be associated to the intercepting device 10; in this case, the position switch or sensor shall be properly connected to the control system of the machine, and calibrated for detecting the attainment, by the projection AP', of the contact position on one of the two stops, like for example the stop 18A.
The operation of the dishwasher according to the proposed variant is the following.
The user loads the dishes in the basket set for the execution of the reduced washing cycle (indicated on the machine's handbook), which in the example is the upper basket 9.
After selecting and starting the said cycle, the first phase (prewash) starts with the corresponding loading in tank 1 of the required water quantity.
During said loading, the control system of the machine checks, by means of the mentioned position switch or sensor, if the projection AP' and plug 14 are in the correct closing position of the outlet 13A and opening of the outlet 13B of the intercepting device 10.
In the negative, the control system of the machine enables the power supply of motor 15, until the switch or sensor detects that the above-mentioned correct position has been reached (notice that, in compliance with this variant, the device 10 can be provided with an electric supply being independent from that of pump 3, so that the motor of the first one and of the second one can be driven by the machine control system also at different moments).
At this point, the supply to motor 15 is interrupted, and plug 14 is in closing position of outlet 13A and opening of outlet 13B of the intercepting device 10. This phase of correct positioning of plug 14 is obviously obtained in quite a short time, and during the water loading step in tank 1. In the case in which, on the contrary, the position sensor informs initially the control system that plug 14 is already in the correct position, the motor 15 is not supplied.
Therefore, once the quantity of water required by the first prewash phase has been loaded from the external water mains, the control system controls the activation of the recirculation pump 3, by supplying the motor of the latter.
Due to the closing of branch 4 of the hydraulic circuit, all the washing water shall be pushed by pump 3 in branch 6, and then to the upper sprayer 7, in order to wash the dishes contained in basket 9; the cycle phase proceeds in this way until the washing water is drained from tank 1 by means of the proper pump.
The above-mentioned operating condition of intercepting device 15 is maintained throughout the following phases of the washing cycle, i.e. without the need to carry out further positioning controls of plug 14.
As seen, therefore, in the above way the intercepting device 10 can also be used to execute a reduced washing cycle, with a given basket of the machine (i.e., in the example, the upper basket 9).
On the other hand, it is clear that a washing machine using the fluid intercepting device according to the present invention can be easily prearranged in order to offer the user the possibility to select the basket to be used in order to execute the reduced washing cycle.
For this case, the control system of the machine can be equipped with a special selector means, placed on the control panel of the machine, provided for the choice of the basket to be used; on the other hand, the intercepting device 10 shall be equipped with two position sensors able to detect the required positioning of plug 14 according to what the user has selected, i.e.

the closing position of outlet 13A of the intercepting device 10, when the user has chosen to carry out the reduced washing using the upper basket 9,
or
the closing position of outlet 13B of the intercepting device 10, when the user has chosen to carry out the reduced washing using the lower basket 10.

It is obvious that the type and operation of the two mentioned position sensors shall be similar to the one described previously, and therefore one for detecting that projection AP' has reached the contact position on stop 18A, and the other on stop 18B.
Finally, it is obvious that the sensor/s provided may be provided for detecting directly the position of plug 14, and not indirectly by means of the projection AP'; in this case, the magnetic element mentioned previously shall be associated directly to the plug 14.
Appendix AP' can be integral with the shaft 15A of motor 15, rather than with the transmission element ET; likewise, the same projection AP' can be replaced by at least a projection or a part of the plug 14, and the stops 18A and 18B can be replaced by proper end-of-stroke means being defined within the body 11.
It is anyway obvious that many changes are possible for the man skilled in the art to the intercepting device described as an example, without departing from the inventive idea, and it is also clear that in the practical actuation of the invention the different components, elements and materials described previously may be replaced with technical equivalent elements, provided that such changes fall under the scope of the appended claims.

Claims

Device for intercepting the flow of a fluid that passes through a distributing circuit (4,6), in particular of a washing machine, where the said device (10) comprises
- an actuator (15) presenting a displacement organ (15A) capable of working in two opposite directions, said displacement organ (15A) being able to move a movable shutter member (14) until the latter reaches at least a first working position,

- striker means (AP,AP') that follow the movement of said shutter member (14)- and are capable of coming into contact with respective fixed stopping surfaces (18A,18B), the contact of said striker means (AP,AP') with a first one of said stopping surfaces (18A,18B) corresponding to the attainment by said shutter member (14) of said first working position,
characterised in that said actuator comprises a single phase synchronous motor, and under constancy of electric supply to said actuator (15), the latter is capable of automatically reversing the direction of movement of said displacement organ (15A), as a result of the effect, in particular the mechanical effect, that the contact of said striker means (AP,AP') with one of said stopping surfaces (18A,18B) determines on said displacement organ (15A).
Device, according to claim 1, characterised in that said shutter member (14) is capable of reaching at least a second working position, where the contact of said striker means (AP,AP') with a second of said stopping surfaces (18A,18B) corresponds to the attainment by said shutter member (14) of said second working position.
Device, according to claim 2, characterised in that
- in said first working position, said shutter member (14) provides for closing at least partially a first branch (4) of said circuit and allowing the passage of the flow of the fluid in a second branch (6) of said circuit, and

- in said second working position, said shutter member (14) provides for closing at least partially said second branch (6) and allows the passage of the flow of the fluid in said first branch (4).
Device, according to claim 2 o 3, characterised in that following the automatic reversal of the direction of movement of said displacement organ (15A) determined by said contact of said striker means (AP,AP') with said stopping surfaces (18A,18B), said shutter member (14) is continuously moved in opposite directions for passing in an alternated way between said first and said second working position.
Device, according to claim 1, characterised in that said electric motor (15) of the single-phase synchronous type has a single winding and a permanent magnet rotor.
Device, according to claim 1, characterised in that the said rotor is capable of inverting its direction of angular movement following a braking moment and/or a thrust in the opposite direction, where in particular connection means (15A) are provided between said rotor and said striker means (AP,AP') and said braking moment and/or thrust in the opposite direction is caused by said effect that the contact of said striker means (AP,AP') with one of said stopping surfaces (18A,18B) determines on said displacement organ (15A).
Device, according to claim 1, characterised in that transmission means (ET) are provided between said displacement organ or shaft (15A) and said shutter member (14).
Device, according to claim 1, characterised in that said intercepting device (10) comprises a body (11) within which said shutter member (14) is placed, said body (11) comprising in particular two parts (11A,11B) that are seal coupled.
Device, according to claim 8, characterised in that said body (11) defines an inlet (12) and two outlets (13A;13B) for the fluid flow, said shutter member (14) being placed within said body (11), between said inlet (12) and said outlets (13A.13B).
Device, according to at least one of the previous claims, characterised in that said shutter member (14) has substantially the shape of a hollow cylinder, whose circumference wall lacks a portion.
Device, according to claim 1, characterised in that elastic means are provided, operating between said striker means (AP,AP') and said stopping surfaces (18A,18B), and/or said striker means (AP,AP') has at least partially elasticity features.
Device, according to claim 1 or 2, characterised in that sensor means are provided, for detecting the attainment by said shutter member (14) of at least one of said working positions.
Device, according to the previous claim, characterised in that means are provided for interrupting the electric supply of said motor (15), when said sensor means detect the attainment, by said shutter member (14), of a predetermined position among said working positions.
Device, according to claim 12 or 13, characterised in that said sensor means comprise at least one switch or sensor of the reed type or of the Hall effect type and in that a magnetic element is associated to said striker means (AP,AP)
Device, according to at least one of the previous claims, characterised in that adjustment means are provided, of at least one of said working positions, said adjustment means comprising in particular means for varying the position of at least one of said stopping surfaces (18A,18B).
Dishwashing machine for household usage comprising
- at least a hydraulic circuit having at least a collecting sump of the washing liquid (2), a washing pump (3), at least two liquid sprayers (5,7) and a supply branch (4,6) for each of said sprayers (5,7), where in order to wash the dishes said pump (3) forces the liquid from said sump (1) in said supply branches (4,6) of the hydraulic circuit,

- an intercepting device (10) comprising
- an actuator (15) having a displacement organ (15A) capable of working in two opposite directions, and able to move a movable shutter member (14) until at least a first working position of the latter is reached, in said first working position said shutter member (14) being in particular able to exclude from the hydraulic circuit a first one of said supply branches (4,6),

- striker means (AP,AP') that follow the movement of said shutter member (14) and are capable of coming into contact with respective fixed stopping surfaces (18A, 18B), the contact of said striker means (AP,AP') with a first one of said stopping surfaces (18A,18B) corresponding to the attainment by shutter member (14) of said first working position,
characterised in that said intercepting device is a device according to one or more of claims from 1 to 15.
Dishwashing machine, according to the previous claim, characterised in that said shutter member (14) is capable of reaching at least a second working position, where the second of said supply branches (4,6) is in particular excluded from the hydraulic circuit, where the contact of said striker means (AP,AP') with a second one of said stopping surfaces (18A, 18B) corresponds to the attainment by said shutter member (14) of said second working position.
Dishwashing machine, according to claim 16, characterised in that following the automatic reversal of the direction of movement of said displacement organ (15A) determined by the contact of said striker means (14B) with said stopping surfaces (18A,18B), said shutter member (14) results in being contiguously moved in opposite directions for cyclically passing between said first and said second working position, in particular in order to supply with liquid both said sprayers (5,7) in an alternated way.
Dishwashing machine, according to claim 16, characterised in that sensor means are provided, capable of detecting the attainment by said shutter member (14) of at least one of said working positions, and in that the control system of the machine is programmed to interrupt the power supply of said motor (15), when said sensor means detect that the shutter member (14) has reached a predetermined position among said working positions, in particular in order to supply in a continuous way with liquid only one of said sprayers (5,7).
Dishwashing machine, according to claim 16, characterised in that said actuator (15) is connected electrically in parallel with respect to the motor of said pump (3), in particular in order to realise a simultaneous operation of said intercepting device (10) and of said pump (3).