Patent Description:
It is well known that a machine of this type works with high wash/rinse water temperatures that imply the production of a considerable amount of water vapour, which is also used in the final thermodisinfection phase by generating it in a special steam generator and then injecting it into the wash tank. Therefore, one of the problems in using this machine is to prevent a considerable amount of steam escaping when it is opened at the end of the operating cycle, as well as reducing the temperature in the wash tank so that the washed and disinfected items can be removed without the risk of scalding.

Of course, it would be possible to wait for the temperature in the wash tank to drop naturally so that the steam condenses on the walls of the wash tank and the articles cool down, but the waiting time for such spontaneous cooling is unacceptably long for a professional-type machine that is used frequently. To overcome these problems, the machine must also include a device that condenses the steam before the wash tank is opened, so as to prevent the steam from being discharged into the environment with adverse consequences for the operator and/or other machines in the environment, also due to the considerable variation in temperature and humidity.

<CIT> describes a machine of this type in which a compressor is used to inject cold air into the upper part of the wash tank in order to cool the articles and remove the steam. The air-steam mixture is conveyed downwards into a pipe branching upwards from the wash tank drain duct, this pipe comprising nozzles through which the air-steam mixture is sprayed with cold water from a storage reservoir, which is also used for rinse water. In this way, the steam condenses in the pipe and the water sprays and the water resulting from steam condensation are removed by gravity, as the pipe is connected to the drain duct, while the dehumidified air is discharged outside.

Another machine of this type is described in <CIT>, which differs from the machine described in <CIT> in that the steam is sucked from the top of the wash tank by means of an aspirator placed above it, and then condensed immediately downstream of the aspirator as well as in a condenser placed in the storage reservoir, again by spraying water from the storage reservoir. Other differences are found in the fact that the air is not discharged to the outside but recirculated to the wash tank via an overflow pipe from the storage reservoir, and that the water sprays and the water resulting from steam condensation are still removed by gravity but via a condenser drain pipe separate from that of the wash tank.

Both of these known solutions thus require the presence of an apparatus (compressor or aspirator) to remove the steam from the wash tank, as well as the consumption of a significant amount of water for steam condensation since this water is immediately discharged from the machine together with the water resulting from steam condensation <CIT> discloses a machine for washing and thermodisinfecting sanitary items.

It is therefore an object of the present invention to provide a machine for washing and thermodisinfecting sanitary items which is free from these drawbacks. This object is achieved by means of a machine comprising a storage reservoir which also acts as a condenser and is connected to the wash tank in such a way as to achieve steam removal by means of natural convection, as well as a hydraulic circuit which enables the steam to be condensed with water which is recycled. Other advantageous features of the present machine are specified in the dependent claims.

The main advantage of the present machine is thus that it does not necessarily require a specific apparatus for removing steam from the wash tank, although in an alternative embodiment a fan may be provided to accelerate the removal.

A second significant advantage of this machine derives from the fact that the water used for steam condensation is not discharged but rather recycled, together with the water resulting from steam condensation, so that water consumption in the steam condensation phase is eliminated or at least substantially reduced.

Yet another advantage of the aforementioned machine is that the storage reservoir also acts as a steam condensing device and has a simple structure, which is economical both to manufacture and to install and requires no maintenance.

Further advantages and characteristics of the machine according to the present invention will be apparent to those skilled in the art from the following detailed description of two embodiments thereof with reference to the accompanying drawings, wherein:.

Referring to <FIG> and <FIG>, it can be seen that a machine according to the invention traditionally comprises:.

The innovative aspects of this machine, as mentioned above, reside in the presence of a steam condensation device that receives steam from the wash tank <NUM> by natural convection, and a hydraulic circuit that allows the recycling of the water used in said device. More specifically, the features that distinguish the present machine from the machines of known technique described above are:.

The wash tank <NUM>, being connected to reservoir <NUM> equipped with window <NUM>, communicates with the external environment and is therefore not to be considered a pressure vessel even when saturated with steam during the thermodisinfection phase, although a modest overpressure is in practice present. The bulkhead <NUM>, during this thermodisinfection phase, thanks to the water present inside reservoir <NUM> at such a level as to realise the separation between its two chambers, prevents the steam escaping through the upper conduit <NUM> from passing in significant quantities to the convection chamber through opening <NUM> and thus from reaching the external environment through window <NUM>. Moreover, it is also possible to condense the steam during this phase, by operating pump <NUM> that feeds nozzles <NUM> with water taken from reservoir <NUM> and that is not discharged but falls back into reservoir <NUM> itself together with the water resulting from the condensation of the steam, thus making it possible not to consume water and indeed to accumulate more water, recovering the water used in the steam generator <NUM>.

In the final phase (<FIG>) of steam condensation after thermodisinfection, a portion of the water in the storage reservoir <NUM> is discharged by opening valve <NUM> located on the lower conduit <NUM>, so as to lower the water level to an elevation MIN1 lower than the elevation of the end of the convection pipe <NUM> but corresponding to a sufficient amount of residual water to keep pump <NUM> running without cavitation. The closing of valve <NUM> can be set in various ways, for example by using a level sensor which detects when the MIN1 elevation has been reached, or by using a flowmeter which detects the amount of water which has flowed out of reservoir <NUM>, or by calculating this amount of flowed out water on the basis of the flow rate of the lower conduit <NUM> and timing the closing of valve <NUM> accordingly.

The water drained through the lower conduit <NUM> is discharged to the bottom of the wash tank <NUM> and then reaches the drain siphon, achieving the dual effect of cooling the bottom of the wash tank <NUM> by lowering the temperature inside it without wetting (with non-disinfected water) the newly disinfected items, and of triggering natural convection in the wash tank <NUM> by opening the "water plug" that closed the convection pipe <NUM>.

Convection motion illustrated by the arrows is now created, with the hot steam exiting the top of the wash tank <NUM> through the upper conduit <NUM> and entering the storage reservoir <NUM>, which at this stage acts to all intents and purposes as a condenser in the condensation chamber equipped with nozzles <NUM>. The water remaining inside reservoir <NUM> is recirculated by pump <NUM> to nozzles <NUM> as done previously during the thermodisinfection phase, condensing all the incoming steam, while the dehumidified air passes through opening <NUM> and exits through window <NUM>. The exit of steam from the wash tank <NUM> generates the drawing in of external air entering through the convection pipe <NUM>, and the condensation phase ends when the temperature inside the wash tank <NUM> falls below a preset value.

In the second embodiment illustrated in <FIG>, the steam condensing device is substantially the same but the removal of steam from the wash tank <NUM> is not by natural convection but by forced convection, through the introduction of external air by a fan <NUM>, preferably preceded by a HEPA filter <NUM>, mounted on a branch <NUM> of the convection pipe <NUM>, but it could also be mounted in any other suitable position to make external air enter the wash tank <NUM>. The entry of air creates a slight overpressure in the wash tank <NUM>, so that the air-steam mixture exits the upper conduit <NUM> and the steam is condensed in reservoir <NUM> as explained above.

The addition of fan <NUM> thus does away with the first of the previously mentioned advantages, but allows the time of the steam condensation phase to be shortened since the evacuation flow rate of the wash tank <NUM> with forced convection is obviously greater than the flow rate with natural convection. In this respect, it should be noted that in this case opening <NUM> is preferably smaller in order to limit the passage through bulkhead <NUM>, otherwise the greater flow rate entering reservoir <NUM> could result in a transit time in the condensation chamber insufficient to obtain a complete condensation of the steam by nozzles <NUM> before the air exits through window <NUM>.

Therefore, even though opening <NUM> is unchanged in the figures in the two embodiments, in practice in <FIG> it could have an area of only about <NUM>% of that of <FIG>. Alternatively, bulkhead <NUM> could be provided with means for reducing the area of opening <NUM>, so as to adapt it depending on whether fan <NUM> is activated or not, preferably by correlating said reduction in area to the air flow rate introduced by fan <NUM>.

In addition, it should be noted that in this second embodiment the advantage of the recirculation of water in reservoir <NUM> and of the recovery of water resulting from the condensation of steam is maintained; the consumption of water is even less than in the first embodiment, since the water level is lowered to a MIN2 elevation greater than the MIN1 elevation and insufficient to open the "water plug" which closes the inlet of the convection tube <NUM>. In this way, it is still possible to cool the bottom of the wash tank <NUM>, and the air entering from branch <NUM> is conveyed to the drain duct <NUM>, since the upper end of the convection pipe <NUM> remains closed.

It is clear that the embodiments of the machine according to the invention described and illustrated above are only examples susceptible to numerous variations. In particular, the shape, size and arrangement of the wash tank <NUM>, reservoir <NUM>, pump <NUM>, conduits <NUM>, <NUM> and pipe <NUM> may be varied according to constructional requirements, as long as their relative arrangement allowing the operation described above is maintained.

Finally, the method for condensing the steam present in the wash tank in the final operating phase of a machine according to the first embodiment of the present invention can be summarised in the following steps:.

Similarly, the method for condensing the steam present in the wash tank in the final phase of operation of a machine according to the second embodiment of the present invention can be summarised in the following steps:.

Claim 1:
A machine for washing and thermodisinfecting sanitary items, comprising:
- a wash tank (<NUM>) with a drain duct (<NUM>) extending downwards and comprising a siphon;
- a reservoir (<NUM>), located higher than said wash tank (<NUM>), for the storage of hot or cold water which, during the wash and rinse phases, is sprayed by sprayers and/or nozzles present in said wash tank (<NUM>) and fed by a pump (<NUM>) which draws water from said reservoir (<NUM>);
- a steam generator (<NUM>) that injects steam into the wash tank (<NUM>) through a steam pipe (<NUM>) to achieve thermodisinfection; and
- a controller that manages the operation of the machine's components based on its programming and the values detected by the machine's sensors;
wherein the reservoir (<NUM>)
a) is connected to the wash tank (<NUM>) by means of an upper conduit (<NUM>) extending between the upper parts of said two elements, and a lower conduit (<NUM>) extending between the lower parts of said two elements and provided with a shut-off valve (<NUM>);
b) is connected to the external environment through a window (<NUM>) in its upper part;
c) is connected to said drain duct (<NUM>), upstream of its siphon, by means of a convection pipe (<NUM>) the upper end of which is shaped as an inverted siphon, so that its end is facing downwards and is situated inside the reservoir (<NUM>) at a lower elevation than the point where said convection pipe (<NUM>) enters the upper part of the reservoir (<NUM>);
d) is divided by a partial bulkhead (<NUM>), extending from its ceiling without reaching the bottom, into a condensation chamber into which said upper conduit (<NUM>) enters and a convection chamber into which said convection pipe (<NUM>) enters and said window (<NUM>) is present, said partial bulkhead (<NUM>) being provided with an opening (<NUM>) which puts said two chambers of the reservoir (<NUM>) into communication with each other and is situated at an elevation below said window (<NUM>) and above the end of the convection pipe (<NUM>);
e) is fitted in its condensation chamber with one or more nozzles (<NUM>) fed by said pump (<NUM>) and positioned to condense the steam entering through the upper conduit (<NUM>).