EP2215953B1

EP2215953B1 - Dishwashing machine and relative system for drying dishes

Info

Publication number: EP2215953B1
Application number: EP20100152220
Authority: EP
Inventors: Luciano Berti; Lucio Tiziano Gaetano Araneo; Marco Colombo
Original assignee: Comenda Ali SpA
Current assignee: Comenda Ali SpA
Priority date: 2009-02-04
Filing date: 2010-02-01
Publication date: 2015-04-08
Anticipated expiration: 2030-02-01
Also published as: EP2215953A1; ITMI20090135A1; IT1398727B1; ES2541675T3

Description

The present invention refers in general to a dishwashing machine and, more in particular, to a system for drying dishes for a dishwashing machine.
In order to take care of the washing and the subsequent drying of the dishes in big canteens, hospitals, hotels and, in general, in any situation in which there is a continuous and considerably large work load, it is known to use dishwashing machines of the so called "tunnel" type. These dishwashing machines generally comprise a plurality of operation areas, or modules, arranged in series that are crossed, during the operation of the machine, by the dishes to be washed placed on suitable transport means, such as conveyor belts or mobile baskets. A tunnel type dishwashing machine normally comprises, in order, a pre-washing area of the dishes, an actual wash area, a rinse area and a drying area of the dishes themselves.
The dish transport means can be actuated according to at least two operation speeds, which can be selected depending on the type and on the number of dishes, as well as depending on how dirty they are. The variation of the speed of such transport means is, clearly, in inverse proportion to the variation of time the dishes have been subjected to the water jets in the pre-washing and washing areas of the machine.
In tunnel type dishwashing machines, the drying of the dishes is commonly carried out within modules provided with one or more fans, which recirculate the air from the drying area itself and take a portion of air from outside to convey it onto the dishes passing through. Suitable heating means thus provide for increasing the temperature of the air conveyed by the fans, so as to ensure a more effective drying of the dishes.
An embodiment of such a tunnel type dishwashing machine is disclosed, for example, in document DE 78 00 591 U1
However, conventional tunnel type dishwashing machines are not without drawbacks.
In a tunnel type dishwasher the temperature rises from the area in which the dishes come into the machine towards the area in which the dishes come out from the machine itself. Consequently, the thermal gradient generates a convective motion that ends up outside the machine (tunnel effect), causing there to be a great energy dispersion and a worsening of the working conditions of the operators.
Moreover, in a tunnel type dishwasher the drying module sucks in a portion of air from outside, recycling the remaining part of air from inside the module itself. This causes hot air to come out into the surrounding area, increasing the tunnel effect and uselessly heating the dishes.
Finally, in a tunnel type dishwasher the dishes accumulate heat while passing within the tunnel. The quantity of heat accumulated is related to the material such dishes are made from. The heat accumulated by the dishes is let off into the area surrounding the machine, thus reducing the energy efficiency of the machine itself.
The purpose of the present invention is, therefore, that of solving the problems of tunnel type dishwashers according to the prior art, by providing a dishwashing machine and a relative system for drying dishes that make it possible to carry out the drying step of the dishes themselves in an effective manner, independently from the outside conditions in which the dishwashing machine is operating.
Another purpose of the present invention is that of providing a dishwashing machine and a relative system for drying dishes which make it possible to optimize the electric energy used to carry out the treatment of the dishes.
A further purpose of the present invention is that of providing a dishwashing machine and a relative system for drying dishes which do not negatively affect the surrounding environment in which the machine is operating, i.e. limiting the emissions of heat and of moist air by the machine itself.
These purposes according to the present invention are achieved by making a dishwashing machine and a relative system for drying dishes as outlined in claim 1.
Further characteristics of the invention are highlighted in the dependent claims, which are integral part of the present description.
The characteristics and the advantages of a dishwashing machine and of a relative system for drying dishes according to the present invention shall become clearer from the following description, given as an example and not for limiting purposes, with reference to the attached schematic drawings in which:

figure 1 is a schematic view that shows the main constructive components of a dishwashing machine according to the present invention;
figure 2 is a schematic view of the dishwashing machine of figure 1, in which the energy balance is highlighted;
figure 3 is a schematic view of a component of the dishwashing machine of figure 1, in particular adapted to carry out the drying of the dishes; and
figure 4 is a perspective view of the component shown in figure 3.

With reference to the figures, a dishwashing machine is shown according to the present invention, in particular of the so called tunnel type, wholly indicated with reference numeral 10.
The dishwashing machine 10 comprises, in a per se known manner, at least one pre-washing area or module 12, at least one washing area or module 14 and at least one rinsing area or module 16 that are crossed, during the operation of the machine 10, by the dishes to be washed, placed on suitable transport means 18 such as, for example, conveyor belts or baskets.
The pre-washing module 12 and the washing module 14 respectively have a pre-wash tank 20 and a wash tank 22, operatively connected to one another, and at least one pump 24, 26 adapted to supply pre-washing/washing liquid to a plurality of spray nozzles, upper 28, 30 and lower 32, 34, with respect to the transport means 18 of the dishes.
In turn, also the rinsing module 16 can comprise a pump 36 adapted to supply the rinse water, contained in a tank 38, to a series of spray nozzles, upper 40 and lower 42, with respect to the transport means 18 of the dishes. It can also be foreseen for there to be at least one boiler 44, or an equivalent heating device, which is able to heat the water to be supplied during the rinsing of the dishes within the rinsing module 16.
The machine 10 finally comprises at least one drying area or module 46, positioned downstream of the rinsing module 16. Inside the drying module 46, as shown in figure 3, one or more blade fans 48 are foreseen which are suitable for conveying the air taken from outside, at high speed onto the dishes passing through the drying module 46 itself. Advantageously, according to the present invention, the drying module 46 also has at least one dehumidifying device 50 which is able to dehumidify the air conveyed by the fans 48 onto the dishes passing through the drying module 46 itself. Therefore, thanks to the use of the dehumidifying device 50, the drying module 46 of the dishwashing machine 10 is able to carry out the drying of the dishes by blowing dry air onto them, at high speed.
In detail, the drying module 46 is provided with a plurality of closed ducts 54, that is to say without any type of openings that allow air to be exchanged with outside, which are able to convey the dry air, coming from the dehumidifying device 50, towards the dishes passing through the drying module 46 itself. In other words, the air used in the drying module 46 of the dishwashing machine 10 is completely recycled and there is no addition of air from outside. The temperature and humidity conditions of the air that licks the dishes is such as to absorb the drops of water on the dishes themselves while simultaneously absorbing their heat, bringing them back to a temperature that is close to room temperature.
According to the example embodiment of the machine 10 shown in the figures, the dehumidifying device 50 of the drying module 46 is made up of a heat pump, provided with an evaporator/condenser group 52 that in turn comprises a pair of evaporator elements and a pair of condenser elements. The dry air, dehumidified by the heat pump, hits the dishes passing through on the transport means 18 and makes the residual water present on the dishes themselves evaporate, becoming humid.
The moist air is thus sucked in by suitable suction means present in the drying module 46 and it is passed through the evaporator of the evaporator/condenser group 52, in such a manner that the moisture contained in it condensates and is able to be discharged.
The dehumidified air finally continues its path within one of the condensers of the evaporator/condenser group 52, thus returning to the initial temperature and humidity values. The possible excess energy of the refrigerating cycle, which is carried out inside the heat pump, is given up to the water of one of the tanks 20, 22 and/or 38 through the other condenser of the evaporator/condenser group 52.

By using the dehumidifying device 50 on the dishwashing machine 10 it is thus possible to efficiently eliminate the water from all the dishes passing through the machine 10 itself for numerous types of operative conditions. As an example, the following table shows the amount of water (in grams per single dish) that it is possible to eliminate from some dishes based upon the supplying conditions (in dishes per hour) of the dishwashing machine 10.

Dishes	Amount of water eliminated [gldish]	*Number of dishes introduced into the machine [dish/h]*
dishes (porcelain, polycarbonate)	7.96	1800 ÷ 9500
trays (melamine, various plastic materials)	23.27	500 ÷ 4750
glasses (glass)	8.83	2500 ÷ 7500

By using the dehumidifying device 50 on the dishwashing machine 10 it is also possible to obtain, as shown in figure 2, an almost zero exchange air flowrate between the machine 10 itself and the outside, to the benefit of the operative conditions of the working personnel. At the same time it is ensured that the dishes come out from the machine 10 at room temperature once they have been washed and dried, so as to be able to be used again immediately. Finally, it can be noted how the energy recovered from the dishes, and the energy introduced by the compressor of the dehumidifying device 50 and by the fans 48, can be given up to a tank containing water that can be heated up to 70°C, with obvious advantages in terms of energy saving.
It has thus been seen that the dishwashing machine and the relative system for drying dishes according to the present invention achieve the purposes previously highlighted, in particular obtaining the following advantages:

effective drying of the dishes, since it is carried out with cold and dry air;
containment of the process air inside the machine, with consequent reduction of the energetic dispersion in the form of latent and sensible heat;
recovery of the heat from the dishes, that can be used for heating the tanks.

The dishwashing machine and the relative system for drying dishes of the present invention thus conceived can in any case undergo numerous modifications and variants, all covered by the same inventive concept; moreover, all the details can be replaced by technically equivalent elements. In practice the materials used, as well as the shapes and sizes, can be any according to the technical requirements.
The scope of protection of the invention is thus defined by the attached claims.

Claims

Dishwashing machine (10) comprising:
- at least one pre-wash area (12) provided with means (20, 24, 28, 32) for pre-washing dishes,

- at least one wash area (14) provided with means (22, 26, 30, 34) for washing dishes,

- at least one rinse area (16) provided with means (36, 38, 40, 42) for rinsing dishes, and

- at least one drying area (46) provided with means (48) for drying dishes,
said areas (12, 14, 16, 46) being arranged in series and being crossed by means (18) for transporting dishes, said drying area (46) comprising at least one dehumidifying device (50) which is able to dehumidify the air conveyed by said drying means (48) onto the dishes passing through said drying area (46), characterised in that said dehumidifying device (50) is made up of a heat pump provided with an evaporator/condenser group (52) which comprises in turn a pair of evaporator elements and a pair of condenser elements, said drying area (46) comprising suction means which suck moist air, coming from the drying of the dishes, and convey it through a first evaporator element of said evaporator/condenser group (52), in such a manner that the moisture contained in the air condensates and is able to be discharged, said drying area (46) being further provided with a plurality of closed ducts (54), that is to say without any type of openings that allow air to be exchanged with outside, that are able to convey dry air, coming from said dehumidifying device (50), towards the dishes passing through said drying area (46), said drying area (46) thus being able to carry out the drying of the dishes by blowing completely recycled dry air, at high speed, onto the dishes, one of the two condenser elements of said evaporator/condenser group (52) being capable to give the possible excess energy of the refrigerating cycle, which is carried out inside the heat pump (50), to one of the means (20; 22; 38) for pre-washing, washing and/or rinsing dishes.
Dishwashing machine (10) according to claim 1, characterised in that said means (20, 24, 28, 32) for pre-washing dishes comprise a pre-wash tank (20) and at least one pump (24) adapted to supply pre-wash liquid to a plurality of upper (28) and lower (32) spray nozzles with respect to said means (18) for transporting dishes.
Dishwashing machine (10) according to anyone of the preceding claims, characterised in that said means (22, 26, 30, 34) for washing dishes comprise a wash tank (22), operatively connected to said pre-wash tank (20), and at least one pump (26) adapted to supply wash liquid to a plurality of upper (30) and lower (34) spray nozzles with respect to said means (18) for transporting dishes.
Dishwashing machine (10) according to anyone of the preceding claims, characterised in that said means (36, 38, 40, 42) for rinsing dishes comprise a pump (36) adapted to supply the rinse water, contained in a tank (38), to a series of upper (40) and lower (42) spray nozzles with respect to said means (18) for transporting dishes.
Dishwashing machine (10) according to claim 4, further comprising at least one heating device (44) which is able to heat the water to be supplied during the rinsing of the dishes within said rinse area (16).
Dishwashing machine (10) according to anyone of the preceding claims, characterised in that said means (48) for drying dishes comprise one or more blade fans.