EP0119517B1

EP0119517B1 - Dishwashing machine with alternated supply of the rotating collectors

Info

Publication number: EP0119517B1
Application number: EP84102079A
Authority: EP
Inventors: Marcello Premoli
Original assignee: Indesit Industria Elettrodomestici Italiana SpA
Current assignee: Indesit Industria Elettrodomestici Italiana SpA
Priority date: 1983-03-02
Filing date: 1984-02-28
Publication date: 1988-10-05
Also published as: DE3474406D1; EP0119517A1

Description

The present invention relates to a dishwashing machine comprising a work programme controller, a wash chamber, a number of inlet pipes, at least two rotating spraying arms fitted inside the wash chamber, water pump means including an electric motor and two water pumping units, each unit being connected to a pipe supplying one of the said rotating spraying arms.
One of the main problems related to dishwashing machines is how to cut down the energy consumption and to that end certain types of dishwashing machines with more than one wash basket provide for supplying alternately the two rotating spraying arms.
In this way, without impairing the device efficiency for a given wash cycle, the amount of water required for wash steps is smaller and a less powerful wash pump can be used, reducing electricity consumption both for operating the pump motor and heating the water.
A number of devices are also known to alternately supply the two rotating spraying arms mentioned above, but they present the drawback of having to be controlled from outside the inlet pipes, raising the obvious problem of sealing said pipes to withstand the internal pressure exerted by the water at the point where the control device comes out.
A further drawback is caused by the seizing up or jamming of the control device caused by food waste and scale in the wash water in the form of detritus. During the wash operation, these matters get inside the sealing points so as to cause the said seizing up when the water is drained off and the inside parts of the appliance dry off.
Moreover, a functional complication the said devices usually cause is that the control device is generally driven by an additional electric motor or electromagnet.
It is also known (see patent US-A-4.004.600 by Corn) the use of devices presenting two centrifugal impellers splined to the same shaft of an electric motor. In said embodiment a one-direction electric motor is used and the two centrifugal impellers are placed at different heights, consequently according to the quantity of water present in the tank both the impellers or only the lower one work. In this way in the standard device cycle both the spray nozzles are supplied, whereas in the economy wash cycle only the lower spray arm is feeded. The quantity of water present in the tank is determined by the dishwashing machine timer depending if the wash cycle chosen is standard or economy, so that according to said choice both the spray nozzles work at the same time during the standard cycle or only the lower one during the economy cycle.
It is also known (see patent US-A-3.179.307 by Duncan) the use of a reversible electric motor with two impellers, one for the water inlet in the wash tank when the motor turns in a first direction of rotation and the other for the wash water outlet when the motor turns in a second direction of rotation.
It is also known (see German Patent application DE-A-2 304 035) the use of two separate impellers, one for supplying water to the upper spraying arm, and the other for supplying water to the lower spraying arm.
However these known devices do not give any teaching how to solve in a simple way the problem of the alternated supply of the lower rotating spraying arm and of the upper rotating spraying arm during the same wash cycle in order to reduce the quantity of water present in the tank and consequently the consumptions for all the wash cycles.
Thus aim of the present invention is to show a dishwashing machine avoiding the abovesaid drawbacks and to indicate a very simple and reliable way to obtain the alternated supply of the rotating spraying arms during a wash cycle, without the help of any device external as to the water supply pipes.
With these aims in view the present invention relates to a dishwashing machine comprising a work programme controller, a wash chamber, a number of inlet pipes, at least two rotating spraying arms fitted inside the wash chamber, water pump means including an electric motor and two water pumping units, each unit being connected to a pipe supplying one of the said rotating spraying arms, characterized in that said two water pumping units are combined in such a way that they are selectively activated or deactivated depending on the direction of rotation of said electric motor.
Further aims and advantages of the present invention will be clear from the following detailed description and the attached drawings, provided by way of an explanatory and nonlimiting example, in which:

figure 1 shows a cross section of the dishwashing machine subject of the present invention;
figure 2a shows a cross section and figures 2b and 2c two orthogonal projections of a variation of the present invention,
figure 3 shows an axial section of the variation shown in figure 2 and
figure 4 shows an axial section, 90° turned as to the section of figure 3, of the variation shown in figure 2.

With reference to fig. 1, it shows a sump 1 of a dishwashing machine, separated from the wash chamber (not visible in the figure) by means of a filter 2, in which the wash water is stored, and having at its bottom an outlet 3 which ramifies in a first pipe 4 and second pipe 5.
The first pipe 4 ends in an inlet 6 of an upper pressure chamber 7, which has also a lateral outlet 8, whereas the second pipe 5 ends in an inlet 9 of a lower pressure chamber 10, which has also a lateral outlet 11.
Pressure chambers 7 and 9 are superimposed and communicating and have their two inlets 6 and 9 in their lower central side, while from their lateral outlets 8 and 11 ramify two connecting pipes 12 and 13, from which the water flows respectively to the two rotating spraying arms of the dishwashing machine, not visible in the figure.
Connecting pipe 12 for example can supply the upper rotating spraying arm, while connecting pipe 13 can supply the lower rotating spraying arm.
Inside the upper pressure chamber 7 it is fitted an upper centrifugal impeller 14 and inside the lower pressure chamber 9 it is fitted a lower centrifugal impeller 15.
The paddles of the two centrifugal impellers are directed toward opposite directions, both protrude downwardly and are splined coaxially on the same shaft 16 of an electric motor 17, commanded by a work programme controller 18 of the dishwashing machine.
The electric motor 17 is placed laterally to sump 1, the shaft 16 of which is downwardly directed, and is fastened to the same sump 1 in a known way.
While functioning, the motor 17 is commanded by the work programme controller 18 of the dishwashing machine, which "decides", according to the programme chosen by the user, when, how long and in which direction it must turn.
It is obvious that when two centrifugal impellers with their opposite-directed and integrally connected paddles rotate in opposite directions, only one at a time is "working" since the impeller, which rotates in the direction opposite to the paddles direction, is idle because it does not create any pressure in the inlet pipe. Moreover it must be remembered that a number of pipes suitable to allow the air in, ease the dispriming of the "active" centrifugal impeller when the reversal of the motion of rotation occurs.
Consequently, when the direction of rotation of the electric motor 17 is reversed, also the centrifugal impeller, which pumps water, is changed: for example when the electric motor 17 turns clockwise, the upper centrifugal impeller 14 works and the water is pumped to the upper rotating spraying arm, but when the electric motor 17 turns counterclockwise it is the lower centrifugal impeller 15 that works and the water is pumped to the lower rotating spraying arm.
In this way, by means only of the work programme controller 18 command, which is consequently planned and built to carry out such inversion at the desired intervals, the direction of rotation of the electric motor 17 is reversed, and as a consequence the desired alternation in the supply of the two rotating spraying arms is obtained without any auxiliary device external to the water inlet pipes from sump 1 to the rotating spraying arms.
With reference to figures 2a, 2b and 2c, which show a variation to the alternated supply device as shown in the previous figure, we can see an impeller 21 consisting of a single piece with a hole 22 in the middle, across which said impeller is splined to the shaft 16 of the electric motor 17, an upper section 23 consisting of a number of radial blades 24, (that can be seen better in the top view showed in figure 2c), a lower section 25 including a number of helical blades 26, (that can be seen better in the bottom view shown in figure 2b). The upper section 23 of the impeller 21 includes also a first protruding collar 27, a second one 28 and a third one 29 whose function will be better explained afterwards. The lower section 25 of the impeller 21 is fundamentally represented by a flat ring 30 placed under helical blades 26, said flat ring 30 having also a hole 31 in its middle part for the wash water inlet.
From figure 3, in which the same particulars of figure 2 are indicated using the same numbers, we can see that the impeller 21 is placed inside a space between a sump 32 and a cover 33, both having a number of clearance holes 34 and 35 which permit to connect them by means of screws or nuts and bolts (not visible in the figure) in order to form the envelope of the impeller 21. The cover 33, has in its inner part in correspondence to the first 27 and the second 28 collar of the impeller 21, a first 36 and a second 37 protruding collar, which together with the first 27 and the second 28 collar of the impeller 21 form a labyrinth course 38 separating a first pressure chamber 39 from a second pressure chamber 40.
Figure 4, in which the same particulars of the above figures are indicated using the same numbers, shows an inlet pipe 42 for wash water, flowing into the central lower part of the first pressure chamber 39 and a first outlet pipe 43 which branches off at a side of the pressure chamber 39 itself allowing the wash water to reach a first rotating spraying arm of the dishwashing machine, not shown in the figure. A second inlet pipe 44 for the wash water flowing into the upper central part of the second pressure chamber 40 and a second outlet pipe 45 which branches off at a side of the pressure chamber 40 itself and allows the wash water to reach a second rotating spraying arm of the dishwashing machine, not shown in the figure. Both the two inlet pipes 42 and 44 draw the water from the wash tank 1. Besides it is visible a nut 46 used to fasten the impeller 21 to the shaft 16 of the electric motor 17.
The device for the alternated supply of the rotating spraying arms described in the present variation works as follows: when the electric motor turns, it makes the impeller 21 turn too, while the sump 32 and the cover 33 stand still so that the first 27 and the second 28 collar of the impeller 21 move within the first 36 and the second 37 collar of the cover 33. The helical blades 26 are set in such a way that in a first direction of rotation (clockwise for example) they work, consequently the wash water coming from the inlet pipe 42 is pumped from the first pressure chamber 39 to the outlet pipe 43 and from the latter to the first rotating spraying arm. Of course in the meantime also the radial blades 24 of the impeller 21 are turning, but the inlet pipe 44 and the outlet pipe 45 are positioned so that by means of this first direction of rotation of the electric motor 17 the radial blades 24 would suck the water (supposing that there is any) from the outlet pipe 45, which is connected with the second rotating spraying arm, for carrying it inside the second pressure chamber 40. Thus in this first direction of rotation no water is sent to the second rotating spraying arm. The labyrinth course 38 separating the first pressure chamber 39 from the second pressure chamber 40 limits the transfers of wash water from said second pressure chamber 40 to said first pressure chamber 39.
When the electric motor is caused to turn in a direction opposite to the former (counterclockwise for example), by means of a proper timer control, the helical blades 26 do not work and no water is sent to the first rotating spraying arm, whereas the radial blades 24 pump the water coming from the second inlet pipe 44 from the second pressure chamber 40 to the second outlet pipe 45 and from this to the second rotating spraying arm. In this wash phase too the labyrinth course 38 limits the transfer of water from the first pressure chamber 39 to the second pressure chamber 40 and therefore there is no mutual interference in the supply of the two rotating spraying arms.
In another variation the upper section 23 of the impeller 21 may have a number of helical blades set in a direction opposite as to those ones of its lower section 25.
In a further variation a number of holes may be done in the first outlet pipe 43 of the first pressure chamber 39 and in the second outlet pipe 45 of the second pressure chamber 40, in such a way that from such holes a certain amount of air may come in such section of the impeller 21, making the dispriming easier, when the relative section of the impeller 21 placed inside said second pressure chamber 40 turns in the direction in which it has not to work.
From the description made, the advantages of the dishwashing machine with alternated supply of the rotating spraying arms being subject of the present invention result clear. In particularthey are represented by the fact that said alternated supply is obtained without adding any device external to the water inlet pipes by means of a simple reverse of the motion of the electric motor, by the fact of having an en bloc double impeller which takes the place of two distinct impellers, by the fact of having a labyrinth course between the two pressure chambers limiting the wash water transfers and by the fact of having quite small dimensions, lower production and mounting costs in respect of the known technique.
Obviously numerous other variations are possible, for the man skilled in the art, to the dishwashing machine with alternated supply of the rotating spraying arms being subject of the present invention without, however, departing from the scope of the present invention.

Claims

1. Dishwashing machine comprising a work programme controller (18), a wash chamber, a number of inlet pipes, at least two rotating spraying arms fitted inside the wash chamber, water pump means including an electric motor (17) and two water pumping units, each unit being connected to a pipe supplying one of the said rotating spraying arms, characterized in that said two water pumping units (7, 14, 39, 23; 10, 15, 40, 25) are combined in such a way that they are selectively activated or deactivated depending on the direction of rotation of said electric motor (17).

2. Dishwashing machine according to claim 1, characterized in that each one ofthe said two water pumping units (7, 14, 39, 23; 10, 15, 40, 25) comprises a centrifugal impeller (14, 15) having the paddles directed toward opposite direction relatively to the paddles of the other centrifugal impeller.

3. Dishwashing machine according to claim 1, characterized in that said direction of rotation of said electric motor (17) is commanded by said work programme controller (18).

4. Dishwashing machine according to claim 1, characterized in that each one of the said two water pumping units (7, 14, 39, 23; 10, 15, 40, 25) comprise a pressure chamber (7, 10) in which the said centrifugal impeller (14, 15) is fitted and a shaft (16) of the said electric motor (17) is provided for having the two centrifugal impellers (14, 15) splined to it.

5. Dishwashing machine according to claim 4, characterized in that the said pressure chambers (7,10) are superimposed and communicating, that these are fitted close to a sump 1, have a number of inlet pipes (6, 9) in their lower central side to which the water flows from the wash chamber and a number of lateral outlets (8, 11) to which connecting pipes (12, 13), in-letting the water respectively to the two rotating spraying arms, are connected.

6. Dishwashing machine according to claim 2, characterized in that the blades of said centrifugal impellers (14,15) protrude downwardly in orderto guarantee the pumping of the water also with a minimum quantity of water in said sump (1).

7. Dishwashing machine according to claim 3, characterized in that the said work programme controller (18) is conceived to command the commutation between said first and second direction of rotation of said electric motor (17) with the desired frequency.

8. Dishwashing machine according to claim 1, characterized in that the said two water pumping units (7,14,39,23; 10,15,40,25) include an en bloc double impeller (21) having two distinct sections (23, 25) which are selectively activated depending on the direction of rotation of said electric motor (17).

9. Dishwashing machine according to claim 8, characterized in that the said impeller (21) has in the said upper section (23) a second set of blades (24) and in the said lower section (25) a first set of blades (26).

10. Dishwashing machine according to claim 9, characterized in that the said first set of blades (26) of the said impeller (21) are of the helical type whereas the second set of blades (24) of the said impeller (21) are of the radial type.

11. Dishwashing machine according to claim 9, characterized in that both the first and the second set of blades of said impeller (21) are of the helical type and are directed toward opposite directions.

12. Dishwashing machine according to claim 9, characterized in that said first set of blades (26) of said impeller (21) is placed inside a first pressure chamber (39) and that said second set of blades (24) of said impeller (21) is placed inside a second pressure chamber (40) connected to the first (39).

13. Dishwashing machine according to claim 12, characterized in that said first pressure chamber (39) is obtained by joining a part of a cover (33) and a part of a sump (32).

14. Dishwashing machine according to claim 12, characterized in that the said second pressure chamber (40) is obtained by joining a part of a cover (33) and a part of said upper section (23) of said impeller (21).

15. Dishwashing machine according to claim 12, characterized in that the two said pressure chambers (39, 40) are separated by flow limiting devices (27, 28, 36, 37).

16. Dishwashing machine according to claim 15, characterized in that said flow limiting devices (27, 28, 36, 37) form a labyrinth course (38) limiting fundamentally the flow of wash water from said first pressure chamber (39) to said second pressure chamber (40) and vice versa.

17. Dishwashing machine according to claim 15, characterized in that said flow limiting devices include a first (27) and a second (28) protruding collar positioned on said upper section of said impeller (21) and a first (36) and a second (37) protruding collar positioned on the inner part of said cover (33).

18. Dishwashing machine according to claim 17, characterized in that said first (27) and second (28) protruding collars of said impeller (21) and said first (36) and second (37) protruding collars of said cover (33) are positioned so as to result staggered one as to the other and to give rise to a labyrinth course (38).

19. Dishwashing machine according to claim 8, characterized in that said sections (23, 25) of said impeller (21) supply a first (43) and a second (45) outlet pipe and in that in said outlet pipes (43, 45) a number of holes are made, through which air may enter, with the purpose of making easier the dispriming of that section (23, 25) of the said impeller (21), that should not work during that wash phase.