DISHWASHER

Technical field

The present invention relates to a dishwasher.

State of the art

Dishwashers are known comprising:

i) a washing compartment suitable to contain the dishes to be washed; ii) first spraying means of the dishes;

iii) second spraying means of the dishes;

iv) directing means of a washing liquid at least towards the first or the second spraying means; said directing means comprising:

- an electric motor;

- a rotating element which can be set in rotation by the motor and comprising a plurality of outlet holes of the liquid; according to the degree of rotation of the rotating element the holes can be facing one or more holes that supply corresponding spraying means (in this way it is possible to decide whether to supply only the first spraying means, only the second spraying means or both the spraying means);

- a cam profile and a switch having a mobile part adapted to determine the opening/closing state of said switch; a rotation of the rotating element determining a rotation of the cam profile and consequently the sliding of the mobile part of the switch along the cam profile to determine the opening/closing of the switch; said cam profile comprises a plurality of grooves into which the mobile part of the switch is inserted determining the opening thereof; when the mobile element of the switch is in the stretch between two consecutive grooves the switch remains closed; according to which and how many spraying means are chosen to be supplied the switch can be found in a corresponding groove.

A drawback of this embodiment is connected with the complexity of identifying a reference angle zero on the cam profile.

Aim of the invention In this context, the technical task underpinning the present invention is to optimise the components of the dishwasher making the steps of unloading and loading the washing liquid from/into the dishwasher particularly quick. On this point, the object of the present invention is to provide a dishwasher that allows quicker identification of an angle zero of a cam profile being part of washing liquid directing means.

Brief description of the drawings

Further characteristics and advantages of the present invention will become more apparent from the following indicative, and hence non- limiting, description of a preferred, but not exclusive, embodiment of a dishwasher as illustrated in the appended drawings, in which:

- Figure 1 shows a schematic view of a dishwasher according to the present invention;

- Figure 2 shows a wiring diagram of a device according to the present invention;

- Figure 2a shows a modified wiring diagram of a device according to the present invention;

- Figure 3 shows a component of a dishwasher according to the present invention.

Detailed description of preferred embodiments of the invention

The subject matter of the present invention is a dishwasher 1 comprising a washing compartment 2 suitable to contain the dishes to be washed. Typically the dishwasher 1 comprises one or more dish support racks. Such racks, at least in an operating configuration of the dishwasher 1 , are inside the washing compartment 2. As exemplified in Figure 1 such racks may comprise an upper rack 42 and a lower rack 32.

The dishwasher 1 comprises first spraying means 3 for spraying the dishes, for example a rotating sprayer. Appropriately the first spraying means 3 could be positioned below the lower rack 32. The first spraying means 3 are positioned in the washing compartment 2.

The dishwasher 1 further comprises second spraying means 4 for spraying the dishes, for example a rotating sprayer. Appropriately the second spraying means 4 could be positioned between the lower rack 32 and the upper rack 42. The second spraying means 4 are positioned in the washing compartment 2. In a particular embodiment third spraying means 43 may be present comprising for example a shower positioned higher than the upper rack 42.

Appropriately the dishwasher 1 comprises directing means 5 for directing a washing liquid at least towards the first or the second spraying means 3, 4. The directing means 5 could also direct the washing liquid towards the third spraying means 43 (if present).

In particular, the directing means 7 can:

-supply alternatively the first or second or third spraying means 3, 4, 43 according to the specific requirements of the washing cycle;

-simultaneously supply at least one pair chosen from the first, second and third spraying means 3, 4, 43;

-simultaneously supply the first, second and third spraying means 3, 4, 43. The directing means 5 comprise:

-an electric motor 50 (typically an electric motor powered with alternating current; for example a synchronous motor);

-a rotating element 51 that can be set in rotation by the motor 50 and comprising a set consisting of one or more washing liquid outlet holes (such rotating element 51 is integral with a shaft moved by the electric motor 50); the washing liquid outlet holes are eccentric with respect to the axis of rotation of the rotating element 51 (this could also be repeated in the event of there being only one outlet hole, but this embodiment is not preferable).

The directing means 5 also comprise a cam profile 53 and a switch 54 having a mobile part adapted to determine the opening/closing state of said switch 54. Appropriately the mobile part of the switch 54 is in contact with the cam profile 53 at least when the switch 54 is closed.

Appropriately the liquid outlet hole is supplied by a pump 44 which takes the washing liquid from the bottom of the washing compartment 2.

A rotation of the rotating element 51 (in turn dictated by the motor 50) determines a relative shift of said cam profile 53 with respect to said switch 54 to determine the opening/closing of the switch 54.

The cam profile 53 comprises a plurality of geometric references 6. The positioning of said mobile part of the switch 54 at the geometric references 6 determines the opening of the switch 54. The positioning of said mobile part of the switch 54 between two consecutive geometric references 6 is associated with a closing state of the switch 54. Such geometric references 6 comprise at least a first and a second geometric reference 61 , 62. The first and the second geometric reference 61 , 62 are consecutive to one another and between them the switch 54 remains closed. As exemplified in Figure 3 the geometric references 6 constitute discontinuities of the profile 53.

Appropriately the cam profile 53 extends along a closed line onto itself. The profile 53 is asymmetrical (in particular the closed line along which the profile 53 extends is asymmetrical).

The plurality of geometric references 6 comprises/coincides with a plurality of concavities 63 distributed along the profile 53. Such concavities 63 define grooves in which the mobile part of the switch 54 is intended to be inserted determining the opening of the switch 54 itself. In fact, when the grooves and the mobile part of the switch 54 overlap, the mobile part penetrates into said grooves determining the opening of the switch 54 (usually following the thrust of elastic means).

The cam profile 53 comprises "n" geometric references 6 ("n" being a natural number greater than or equal to 2); in particular "n-1 " geometric references 6 are identical to one another. The remaining geometric reference 6 has different dimensions from the above-indicated "n-1 " geometric references 6.

Preferably the cam profile 53 rotates along with said rotating element 51 .

The switch 54, on the other hand, is constrained to a fixed point. The cam profile 53 is usually afforded on a separate disc from said rotating element 51 . The cam profile 53 comprises a plurality of teeth between which said geometric references 6 are interposed (which are hence concavities 63). An alternative situation may arise, however, wherein the geometric references 6 are projections. In the solution exemplified in Figure 3 the cam profile 53 comprises a series of more external stretches 65 which are staggered by said geometric references 6 (concavities 63). Said series of more external stretches 65 is defined by a set of circumference arches (appropriately such arches all lie on the same imaginary circumference).

Appropriately the directing means 5 comprise activation means 7 of the rotation of the motor 50. The activation means 7 of the rotation of the motor 50 are controlled by an electric signal. Appropriately such electric signal is pulse based. In an alternative embodiment such electric signal is continuous. As will be better explained below, this is very advantageous. The activation means 7 for the rotation of the motor 50 comprise/coincide with a TRIAC 70. On this point, the pulse based or continuous electric signal is applied to the TRIAC 70 through the gate 71 of the TRIAC 70. More generally, the TRIAC 70 enables the motor 50 to be driven. The advantages of continuous driving rather than pulse based driving are: taking less time to find the target position and allowing greater durability and reliability of the TRIAC 70 since fewer activations thereof are required. The dishwasher 1 comprises a first conduit 30 that extends between the first spraying means 3 and said rotating element 51 . In a first configuration of the directing means 5 said outlet hole is in communication with an inlet hole in the first conduit 30. In particular in the first configuration the outlet hole faces the inlet hole. In the first configuration the mobile part of the switch 54 is at said first geometric reference 61 (and advantageously it penetrates into the first geometric reference 61 ).

The dishwasher 1 comprises a second conduit 40 that extends between the second spraying means 4 and said rotating element 51 . In a second configuration of the directing means 5 said outlet hole is in communication with an inlet hole in the second conduit 40; in said second configuration the mobile part of the switch 54 is at said second geometric reference 62 (and advantageously it penetrates into the second geometric reference 62).

In one exemplary embodiment the rotating element 51 comprises a plurality of outlet holes (for example comprised between 4 and 6). According to the degree of rotation of the rotating element 51 one or more of such holes can overlap with the conduits that supply the first or the second or the third spraying means 3, 4, 43 (according to the degree of rotation of the element 51 it can then be decided which spraying means to supply).

The directing means 5 comprise an electric path 8 for electrically powering the motor 50. The path 8 comprises a first branch 81 along which said activation means 7 are arranged (the TRIAC 70). The path 8 further comprises a second branch 82 that by-passes the first branch 81 and along which the switch 54 is arranged. With the switch 54 closed, the second branch 82 short circuits the TRIAC 70 and the motor 50 is powered hence the rotation of the rotating element 51 and the cam profile 53. Appropriately along the second branch 82 there is a shunt resistor 93 (which preferably has a value comprised between 10 and 300 ohm). The directing means 5 comprise a splitter (indicated by reference number 90 in the figures). In particular the splitter 90 comprises a first resistor 91 and a second resistor 92. Purely by way of example the first resistor 91 has a value of approximately 39 kOhm while the second resistor 92 has a value of approximately 10 kOhm. Now reference is made to the embodiment of Figure 2a. This embodiment envisages the use of at least one zener diode 820 along the second branch 82. In particular the second branch 82 comprises two zener diodes 820 connected in series with a common anode. By way of example, the two zener diodes may be the same and such as to have a rated voltage of 5.1 V. With respect to the embodiment of figure 2 the first resistor 91 is replaced by a plurality of resistors 94, 95, 96, a diode 97 being interposed between two of them.

The directing means 5 (but more generally the dishwasher 1 ) comprise retroactive means 9 identifying the opening or closing state of the switch 54. The retroactive means 9 are therefore important for identifying time intervals in which the switch 54 is closed and time intervals in which the switch 54 is open. The directing means 5 (but more generally the dishwasher 1 ) comprise control means that identify the passage of said mobile part of the switch 54 at a predetermined zone of the profile 53 according to the opening or closing duration of at least one of the intervals in which the switch is open or closed.

The control means are operatively associated with said retroactive means 9.

This is in order to identify the passage of the mobile part of the switch 54 at a predetermined zone of the profile 53 (which is therefore identified as "angle zero"). In the preferred embodiment such predetermined zone of the profile is at the geometric reference 6 that is different from all the remaining geometric references 6. At this point the system, according to the rotation imposed by the motor with respect to such "angle zero", can determine which spraying means are supplied at a given moment. For example with reference to the embodiment illustrated in Figure 3 the concavities 63 are identical to one another with the exception of a predetermined concavity (identified by reference X in the example of Figure 3). The control means of the dishwasher 1 comprise means for comparing the duration of each interval in which the switch 54 is closed and a predetermined time interval that is compatible with the shift of the mobile part of the switch 54 along a path connecting said predetermined concavity X and a concavity consecutive to it. In an alternative embodiment, the control means of the dishwasher 1 comprise means for comparing the duration of each interval in which the switch 54 is open and a predetermined time interval that is compatible with the shift of the mobile part of the switch 54 along said predetermined concavity X.

Appropriately the feedback signal of the retroactive means 9 is "deaf" when the TRIAC 70 is driven. Consequently, as previously mentioned, the driving of the TRIAC 70 is pulse based so as to perform the readings of the feedback coming from the retroactive means 9 at the moments in which the driving is OFF.

The use of a zener diode 820 (in particular two connected in series with a common anode) is important since it introduces a decoupling between the first branch 81 and the second branch 82, making it possible to discriminate whether the switch 54 is open or closed even when the TRIAC 70 is closed; in this way the TRIAC 70 can be supplied continuously and at the same time the opening or closing state of the switch 54 can be identified through the retroactive means 9.

The retroactive means 9 and the comparison means comprise/are at least partially integrated in an electronic control unit.

The subject matter of the present invention is further an identification method of an angle zero of the cam profile 53 of a dishwasher 1 having one or more of the characteristics previously described. The method comprises the steps of:

-activating the rotation of the electric motor 50 when the switch 54 is open and is at one of said geometric references 6 (it is specified that the switch 54 being open means a situation in which current cannot transit through the switch 54 itself, as opposed to the situation in which the switch 54 is closed and in which the current can transit through the switch 54 itself); -powering said electric motor 50 making the electric current transit through said switch 54 when the switch 54 is closed and the mobile element is between two consecutive geometric references 6;

-comparing with a predetermined time interval the duration of the time interval in which the switch 54 remains closed during the shift of the mobile part of the switch 54 between two consecutive references or connected with the time in which the switch 54 remains open at one of said geometric references 6. Such predetermined time interval can at worst coincide with only one value.

A shift of the mobile part of the switch 54 along a path connecting a single pair of consecutive geometric references 6:

- is compatible with said predetermined time interval;

- is incompatible with the time connected with the passage of the mobile part of the switch 54 along paths that connect the remaining pairs of consecutive geometric references 6.

The invention as it is conceived enables multiple advantages to be attained.

First of all it enables the angle zero of the rotating element 51 of the directing means 5 to be determined extremely quickly, optimising the components. In fact, the dishwasher 1 is able to determine such angle zero with a simple turn of the rotating element 51 .

The invention as conceived is susceptible to numerous modifications and variants, all falling within the scope of the inventive concept characterised thereby. Furthermore all the details can be replaced by other technically equivalent elements. In practice, all the materials used, as well as the dimensions, can be any according to requirements.