Dishwasher with device for recycling the rinse water

Abstract

 A dishwasher comprises a wash tank with a collecting sump at the bottom and a drain pump (1) that draws the water from said collecting sump and sends it to a drain pipe provided with check valve means suitable to prevent the water from flowing back to the wash tank as well as, downstream from said check valve means (3), an accumulator (4) arranged at a position higher than the collecting sump and having a capacity suitable for storing therein at least 30% of the water of the last rinse of the operating cycle of the dishwasher, there being further provided actuator means (7) operatively connected to a control unit of the dishwasher for the controlled deactivation of the check valve means (3) so as to allow at the proper time the flowing back of the rinse water from the accumulator (4) to the wash tank to perform the initial pre-wash phase of the following cycle.

Description

[0001] The present invention relates to dishwashers, and in particular to a dishwasher provided with a device for recycling the water of the last rinse phase.

[0002] It is known that in a dishwasher the operating cycle substantially consists of the pre-wash, wash, intermediate rinse, final rinse and drying phases. The initial pre-wash phase is useful to remove the largest residues from the dishes and the water used in said phase is then drained and replaced with clean water for the subsequent wash phase.

[0003] In order to reduce the amount of water used in the operating cycle of a dishwasher it is already known to recycle the water of the last rinse of the previous cycle for the pre-wash phase of the following cycle. This recycling is achieved by storing the rinse water in a specific reservoir that is connected to the collecting sump of the wash tank through a relevant hydraulic system with pipes and valves, such that the water can be introduced in the reservoir after the final rinse phase and returned to the tank at the beginning of the following cycle.

[0004] Examples of dishwashers provided with such a rinse water recycling system are found in US 2007-0277854A1 and DE 4243605A1, that disclose hydraulic connecting systems between the storage reservoir and the wash tank in which there is provided a specific valve that closes and opens the access to the reservoir or a two-way valve that directs the rinse water towards the reservoir or towards the drain pipe.

[0005] An alternative to using a specific rinse water storage reservoir is illustrated in WO 2009/027320A1, where the water coming from the hydraulic network is loaded into the wash tank through a reservoir also acting as a heat exchanger for pre-heating the water by recovering the heat released by the wash tank during the wash phases with hot water. In this case, such a reservoir can be used also for the storage of the final rinse water by means of a specific valved duct connecting the wash pump to the reservoir.

[0006] In both types of prior art dishwashers it is in any case necessary to provide the room for the storage reservoir and the relevant hydraulic connecting system. This obviously implies also a higher manufacturing cost both for the additional components (reservoir, pipes, valves, etc.) and the labour required for their installation.

[0007] Moreover, in case the time interval between two successive operating cycles is too long it is preferable not to use the water recycled from the last rinse because bacteria could have developed therein. Therefore, beyond a given time threshold said water is drained prior to the following cycle by suitably activating the drain pump and the valves of the hydraulic connecting system of the storage reservoir.

[0008] Therefore the object of the present invention is to provide a dishwasher that performs the rinse water recycling function with a structure which overcomes the above-mentioned drawbacks. This object is achieved by means of a dishwasher provided with a drain pipe that includes an accumulator arranged downstream from check valve means and at a position higher than the collecting sump, as well as with actuator means for the controlled deactivation of said check valve means. Other advantageous features of the present dishwasher are disclosed in the dependent claims.

[0009] The main advantage of this dishwasher stems from the fact that the rinse water recycling function is performed with a simpler and cheaper structure, which is less bulky and more reliable.

[0010] A further advantage of the present dishwasher is that the possible draining of the rinse water due to reach of the preset time threshold between two successive operating cycles does not require a specific activation of the machine since it can be normally carried out during the following operating cycle.

[0011] These and other advantages and characteristics of the dishwasher according to the present invention will be clear to those skilled in the art from the following detailed description of two embodiments thereof, with reference to the annexed drawings wherein:

Fig.1 is a top plan view, with a broken-away portion, of the wash tank bottom of a dishwasher according to a first embodiment of the invention;

Fig.2 is a diagrammatic side view of the dishwasher of Fig.1 illustrating the position and extension of the accumulator formed in the drain pipe with respect to the wash tank;

Fig.3 is a diagrammatic front view of the dishwasher of Fig.1;

Figs.4 and 5 are enlarged see-through side views of the check valve means and of the relevant actuator in the states, respectively, of active valve means and deactivated valve means; and

Figs.6 and 7 are enlarged see-through side views of the check valve means and of the relevant actuator in the states, respectively, of active valve means and deactivated valve means of a second embodiment.

[0012] Referring to figures 1 to 3, there is seen that a dishwasher according to the present invention is conventionally provided with a drain pump 1 that draws the water from the collecting sump and sends it to the drain pipe 2, that is provided with a check valve 3 suitable to prevent the drained water from flowing back towards the wash tank.

[0013] A first novel aspect of the present invention resides in the fact that the drain pipe 2 includes, downstream from the check valve 3, an accumulator 4 extending in the side portion of the dishwasher, between the wash tank and the outer casing, so as to form a container having a capacity suitable for storing therein at least 30% of the water of the last rinse intended for the following pre-wash phase (indicatively at least 1 liter). At the top of said accumulator 4 there is provided a passage 4a that leads to an adjacent vertical duct 5 which at its bottom end is connected to the terminal portion 6 of the drain pipe that continues outside the dishwasher up to a wall drain.

[0014] For the normal draining of the water, once accumulator 4 is full the water overflows through passage 4a into the adjacent duct 5 that leads it to the terminal portion 6 to be definitively discharged outside the dishwasher.

[0015] As better illustrated in the details of figures 4 and 5, the check valve 3 has an outlet 3a shut by an external flap 3b hinged at the top, so as to allow only the passage of water from the drain pipe 2 to accumulator 4.

[0016] A second novel aspect of the present dishwasher resides in the fact that it is provided with a linear actuator 7, arranged on top of valve 3, whose stem 7a is hinged to a lever 8 connected to a ring 9 rotatable around a pivot 10 located between actuator 7 and valve 3. Ring 9 is arranged around outlet 3a of valve 3, such that it extends at the portion of flap 3b projecting below outlet 3a.

[0017] When the dishwasher control unit, not illustrated, activates actuator 7 extending stem 7a thereof, lever 8 causes the rotation of ring 9 around pivot 10, as shown in Fig.5. The rotation of ring 9 causes in turn the lifting of flap 3b against the pressure of the water column present in accumulator 4, and therefore the deactivation of the check valve 3 thus allowing the water to flow back.

[0018] In this way the water contained in accumulator 4, merely by gravity, crosses valve 3 in the opposite direction passing through outlet 3a and then pipe 2 and the drain pump 1, thus returning to the wash tank to be used by the wash pump in the pre-wash phase. After the water has flowed back from accumulator 4 to the wash tank, it is sufficient to return the linear actuator 7 to its rest position illustrated in Fig. 4 so that flap 3b can return in abutment on outlet 3 a to have the check valve 3 active again.

[0019] It should be noted that the projecting portion of flap 3b on which ring 9 acts may be located also laterally rather than at the bottom, or there could be multiple projections or even a single continuous projection along the whole periphery of flap 3b.

[0020] In the second embodiment illustrated in figures 6 and 7, where the same reference numbers indicate corresponding members, actuator 7 is located to the side of the check valve 3 and rather than acting directly on it by lifting flap 3b, the rotation of lever 8 causes the opening of a plug 11 that normally closes a bypass passage 3c formed in the body of valve 3 under outlet 3a.

[0021] In this way, even if flap 3b remains in abutment on outlet 3a the water contained in accumulator 4 can flow back to the wash tank through the bypass passage 3c that is then closed again by plug 11 by returning actuator 7 to its rest position, which in this case corresponds to the position with stem 7a extended.

[0022] It should be noted that if the control unit determines that too much time has passed since the last cycle to be able to safely recycle the water from the last rinse, it simply does not activate actuator 7 whereby the check valve means remain active. Therefore the pre-wash of the following cycle will be carried out with clean water loaded from the hydraulic network and the water stored in accumulator 4 will be drained during the cycle on the occasion of the first draining phase. Moreover it is obvious that even when the rinse water is recycled it is always possible to add clean water from the hydraulic network to perform the pre-wash.

[0023] It is clear that the above-described and illustrated embodiments of the dishwasher according to the invention are just examples susceptible of various modifications. In particular, the exact structure and relative position of the check valve means and of the actuator means for their controlled deactivation can change somewhat according to specific manufacturing needs. For example, the lifting of flap 3b could be achieved through different means although technically equivalent to the kinematic chain formed by members 7, 7a, 8, 9 and 10 or the opening and closing of the bypass passage 3c could be achieved through different means although technically equivalent to plug 11 and still controlled by actuator 7.

[0024] Similarly, the exact shape and arrangement of accumulator 4 can change according to the required capacity thereof and to the room available between the tank and the outer casing. For example, accumulator 4 could extend also on multiple sides of the tank and/or have a capacity sufficient for storing also the water of the intermediate rinse so as to subsequently perform a longer pre-wash.

Claims

1. Dishwasher comprising a wash tank with a collecting sump at the bottom and a drain pump (1) that draws the water from said collecting sump and sends it to a drain pipe (2) provided with check valve means suitable to prevent the water from flowing back to said wash tank, characterized in that said drain pipe (2) includes, downstream from said check valve means, an accumulator (4) arranged at a position higher than the collecting sump and having a capacity suitable for storing therein at least 30% of the water of the last rinse of the operating cycle of the dishwasher, and in that it further includes actuator means operatively connected to a control unit of the dishwasher for the controlled deactivation of the check valve means.

2. Dishwasher according to claim 1, characterized in that the accumulator (4) extends in the side portion of the dishwasher, between the wash tank and the outer casing, and is provided with a passage (4a) that leads to an adjacent vertical duct (5) which at its bottom end is connected to a terminal portion (6) of the drain pipe (2).

3. Dishwasher according to claim 1 or 2, characterized in that the check valve means consist of a check valve (3) having an outlet (3a) shut by an external flap (3b) hinged at the top and provided with at least one portion projecting with respect to said outlet (3a), and in that the actuator means consist of a linear actuator (7) arranged on top of said valve (3) and whose stem (7a) is hinged to a lever (8) connected to a ring (9) rotatable around a pivot (10) located between said actuator (7) and the valve (3), said ring (9) being arranged around the outlet (3a) such that it extends at said at least one projecting portion of said flap (3b).

4. Dishwasher according to claim 1 or 2, characterized in that the check valve means consist of a check valve (3) provided with a bypass passage (3c) closed by a plug (11), and in that the actuator means consist of a linear actuator (7) suitable to move said plug (11) so as to control the opening and closing of said bypass passage (3c).

Drawing