In particular, the present invention relates to a system for the automatic detection of the liq- uid level in the feeding tanks of said machines, said system controlling automatically the feeding of one or more liquids (typically a mixture of wa- ter and a syrup) into said tanks when the level in the tank sinks below a given minimum value, and stopping said feeding when the pre-established maximum level is reached in the tank.

It is known about groups for the monitoring of the liquid level in the tank and for the automatic feeding of the liquid mixture, consisting of an aqueous solution of syrup, into the tanks of the above-mentioned machines. Said known systems sub- stantially consist of a box comprising: the dosing group for water and syrup; a connection to the wa- ter network; one or more pipes for the taking of the syrups from the various tanks; one or more pipes equipped with automatic joints with sin- gle/double interception for an easy and rapid en- gagement/release without any possibility of dis- charge of the mixture either from the pipe or from the tank, for the feeding of the water-syrup mix- ture into the tanks; pumping means for said mix- ture; sensors for the detection of the liquid level in the tanks according to the conductivity of the water-syrup system in the tank, said sensors being connected to the tank by means of electric cables, so that when said level is below a given limit, said sensors activate the means for the feeding of the mixture into the concerned tank, thus bringing the liquid level in the tank back to its optimum value.

In these known systems the presence of exter- nal electric cables for the transmission of the level signal from the tank is a serious disadvan- tage both from the practical and from the aesthetic point of view. As a matter of fact, during the op- erations of installation/disinstallation and clean- ing of the tanks, said electric cables have to be mounted and dismounted, thus wasting a lot of time.

The present invention therefore aims at carry- ing out a system to overcome the disadvantages and the drawbacks of the known technique.

According to the present invention, said aim is put into practice by introducing a stainless steel cable into the pipes for the feeding of the water-syrup mixture into the tank, said cable ex- tending on the whole pipe length and ending with its free end near the joint for the connection to the tank, so as to overcome the excessive electric resistance of the circuit, said cable being con- nected to said level sensor directly or indirectly on its other end, thus creating one of the two poles of the electric circuit closing on the second pole, consisting of the tank which is grounded through the machine frame and of its metal parts.

Said automatic systems for the filling-up of the tanks are provided with valve means switching the installation from a system for the addition of the mixture into the tank to a system for the auto- cleaning of said installation. To this purpose, the box of the filling system is provided with one or more controlling levers, each corresponding to a switching valve. However, said switching levers might be left in a false position while switching from the work position to the cleaning position (or vice versa) of the lever, that is to say, said lev- ers might be left in the position of total or par- tial closing of the liquid flow, thus obtaining an unwanted pressure increase.

According to another characteristic of the present invention, in order to avoid said drawback, it has been provided to introduce into the rotation area of the switching lever a switch stopping the switching of the lever and forcing to turn the ma- chine off and to turn it on again only when said lever has been positioned correctly.

Further characteristics and advantages of the present invention will be more evident from the following description of a preferred form of em- bodiment of said invention, carried out with refer- ence to the enclosed drawings, in which: Figure 1 is a schematic view in lateral eleva- tion of an installation consisting of a machine for the production of cold drinks, provided with an auto-supplying system according to the present in- vention; and Figures 2 to 4 show an enlarged detail of the group comprising the lever and the switch for the switching from the work position to the auto- cleaning position, and vice versa, belonging to the machine according to the invention.

With reference to the drawings, and in par- ticular to figure 1 of said drawings, the numeral 1 indicates a machine for the distribution of cold drinks. Said machine shows, in a known manner, in its upper portion one or more tanks (not shown) containing a mixture of water and syrup, and in its base a refrigerating group for the cooling of said mixture. The numeral 2 indicates a delivery tap for the distribution of the cold drink.

The numeral 3 indicates a box to which are linked, in a known manner, the pipe 4 for the con- nection to the water network and the pipe (or pipes) 5 for the connection to the tank 6 contain- ing the syrups. The box 3 contains the dosing group mixing water and syrup in dosed amounts, the level sensor, the pump for the feeding of the syrup-water mixture into the tank of the machine 1, and the various signaling systems, such as for instance the system signaling, by means of the led 7 and/or a sound signal, that the syrup tank 6 is empty and has to be replaced. Finally, the box 3 is the starting point of the pipe or pipes 8 for the feed- ing of the water-syrup mixture into the tanks of the machine 1. As indicated by the dashed line, ac- cording to the invention, the pipe 8 for the feed- ing of the water-syrup mixture houses a cable 9 in stainless steel, constituting one of the two poles of the electric circuit linked to the level sensor (not shown), the second pole consisting of the ca- ble 10 grounded through the frame of the machine 1.

The operation of the device described will now be evident. Thanks to the fact that one of the poles of the electric circuit of the level sensor for the liquid in the tank is housed within the flexible pipe 8, the problem of the connection and disconnection of external electric cables for the machine cleaning does not exist any more. Moreover, also from the aesthetic/functional point of view, the machine certainly shows a better aspect without external electric cables.

As mentioned before, the installation can un- dergo an auto-cleaning, thanks to the presence in the box 3 of the levers 11, which constitute switching valves apt to control alternately the flow of liquids through the pipes. Said levers 11 can be turned from a first position (for instance the position indicated with A in figure 2), which might be called the work position, in which the ma- chine works with the auto-feeding of the water- syrup mixture, to a second position, turned of 180° with respect to the previous one (position B of figure 2), in which the installation carries out an auto-cleaning. Obviously, in the switching from po- sition A to position B (or vice versa) the machine has to be turned off and then on again by means of the switch 12.

While doing this, it is necessary to avoid that in the switching from the work position to the cleaning position the levers 11 are left in a false position. To this purpose, the base of the levers 11 has been provided with a disc flange 13, equipped on its rim with two rectangular notches 14, cooperating with the switch 12, which is advan- tageously of the rocking type. Thanks to this ar- rangement, in order to turn the lever 11 it is nec- essary to turn off the machine by lowering one side of the switch below the plane of the flange 13, so as to allow the flange to pass over said switch, so that when the lever has been correctly turned of 180°, the switch 12 is on a notch 14 and can there- fore be reactivated (positions in figure 2 and 3).

If, on the contrary, the lever 11 is not turned correctly (position in figure 4), one side of the switch is below the flange 13, thus preventing the operation of said switch.

Obviously, the present invention is not lim- ited to the forms of embodiment here shown and de- scribed, but relates to all those changes and vari- ants within the ampler idea underlying the inven- tion, substantially as claimed below.