Patent Publication Number: US-2021162436-A1

Title: Automatic humidification system for a dispensing head of a dosing machine of fluid products

Description:
FIELD OF THE INVENTION 
     The present invention relates, in general, to dosing machines for dispensing products such as dyes for paints or the like. 
     More precisely, the invention relates to the dispensing head of such a dosing machine and has been developed, in particular, in view of the application to dispensing of dyes for preparing paints. In the following description, reference will be made to this specific application field without, however, losing generality. 
     STATE OF THE ART 
     A dosing machine for dispensing dyes for preparing paints generally comprises a plurality of containers containing respective dyes which, in the case of so-called “simultaneous machines”, are connected to a single dispensing head by means of respective ducts. A plurality of metering pumps feed metered quantities of dyes from the containers to the dispensing head, which usually comprises a plurality of nozzles with vertical axis parallel to each other, open at the lower ends and enclosed in a tubular member having an open lower edge. 
     Dispensing of the dyes from the nozzles of the dispensing head is typically discontinuous. At the end of the dispensing, elongated drops of dyes are formed, which protrude from the lower ends of the nozzles of the dispensing head: for correct operation of the dosing machine, it is necessary that these drops of dye remain in a fluid state and do not harden. 
     To avoid or limit the risk of hardening of the drops of dye at the lower ends of the nozzles of the dispensing head, the dosing machines may be equipped with a closing device that closes the lower end of the dispensing head at the end of the dispensing of dyes. In this way, the area around the lower ends of the nozzles of the dispensing head is isolated from the external environment, and the drying of the drops of dye due to exposure to air is reduced. The quality of the insulation can be improved by means of a seal in the contact between the closing element and the lower end of the tubular member of the dispensing head, as well as with the aid of a sponge soaked in liquid arranged inside the closing element. This allows maintenance of a humid environment in the area of the dispensing head when the closing element is applied thereto, so as to further hinder the drying of the drops of dye. 
     A solution of this type is described and illustrated in the Italian patent application no. 102019000007192 by the same Applicant, not published at the date of filing/priority of this application, according to which the closing element can be moved with respect to the dispensing head according to a combined roto-translation movement. 
     To reduce the risk of drying of the drops it has also been proposed, in the European patent EP2745943B1, to provide a cooling system for the nozzles of the dispensing head in order to maintain a dew point state of the liquid present inside the nozzles, so as to keep them in a humid state, thus avoiding drying. According to this solution, a cooling element is provided, which is in cooling contact with at least one end part of the dispensing head. 
     This solution, as it is applied directly to the dispensing head, is relatively complicated and its functional effectiveness does not appear to be entirely satisfactory. 
     OBJECT AND SUMMARY OF THE INVENTION 
     The object of the present invention is to make a humidification system available for a dispensing head of a dosing machine for fluid products, particularly (though not exclusively) a tinting machine, which allows auto-humidifying the nozzles of the head, drastically reducing the possibility of drying of the metered product, without the need to be directly applied to the dispensing head. 
     Another object of the invention is to provide a humidification system that is relatively simple, functional and such as to be able to operate automatically in a reliable and safe manner. 
     According to the present invention, this object is achieved by means of a humidification system having the characteristics defined in claim  1 . 
     The claims form an integral part of the disclosure provided here in relation to the invention. 
     One of the characteristic aspects of the humidification system according to the present invention is that it is operatively associated with the cup of the closing element, which is movable between an inoperative distal position with respect to the dispensing head, and a proximal operative position wherein the dispensing head is hermetically sealed and isolated from the surrounding environment. The humidification system according to the invention is designed to automatically generate a humid environment inside the cup of the closing element when it is in the proximal position, and advantageously includes a cooling device consisting of a Peltier cell and a supply circuit of the condensed water from the Peltier cell into the cup of the closing element. Activation and deactivation of the supply circuit are controlled automatically according to the temperature and humidity of the ambient air, as well as the level of the water inside a condensate collecting tank from the Peltier cell and that contained inside the cup of the closing element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional characteristics and advantages of the present invention will become apparent from the detailed description that follows, given purely by way of non-limiting example, with reference to the attached drawings, wherein: 
         FIG. 1  is a schematic perspective view of a dosing machine provided with a humidification system according to the present invention, 
         FIG. 2  is a perspective view from below and on a larger scale of the dispensing head of the dosing machine, with the humidification system, 
         FIG. 3  is a front elevational view of  FIG. 2 , which is partially cross-sectioned, 
         FIG. 4  is a partial perspective view according to the arrow IV of  FIG. 3 , 
         FIG. 5  is a front elevational view of  FIG. 4 , which is on a greater scale and partially cross-sectioned, 
         FIG. 6  is a dorsal elevational view of  FIG. 3 , which is on a greater scale and partially cross-sectioned, and 
         FIG. 7  is a block diagram that exemplifies the operation of the humidification system according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     With initial reference to  FIG. 1 , numeral  10  indicates—in its entirety—a dosing machine suitable for dispensing metered quantities of fluid products, for example, dyes for preparing paints. The machine  10  comprises—in a known way—a stock  12 , which contains a plurality of containers (“canisters”) for the different dyes connected to respective ducts by means of respective metering pumps—not illustrated. 
     The ducts coming from the various containers of the machine  10  are connected to a dispensing head  14  inside which a plurality of vertically-oriented nozzles are arranged in a known way, and connected to the metering pumps. The nozzles of the dispensing head  14  are enclosed within a tubular member  16  having an open lower edge  17  ( FIGS. 3 and 6 ). 
     A base  18  is arranged below the dispensing head, on which containers are placed in which the dyes dispensed by the dispensing head  14  are poured each time. 
     A closing device  20  is operatively associated with the dispensing head  14 , configured to isolate the lower ends of the nozzles of the dispensing head  14  from the external environment, at the end of each dye-dispensing step. 
     The closing device  20  is described and illustrated in the aforementioned Italian patent application no. 102019000007192 by the Applicant: briefly it comprises a stationary support  22  containing a motorized unit for moving a closing element  25  bearing a cup  27  upwardly open. The closing element  25  is carried by an arm  23 , which can be moved angularly and vertically between an open distal position and a closed proximal position, represented in the drawings, relative to the dispensing head  14 . This actuation assembly will not be described in detail here: for the purposes of the present invention it is sufficient to specify that it can perform the combined movement of vertical translation and rotation of the arm  23  and, therefore, of the closing element  25  with the cup  27 . In this proximal closing position, the upper face of the closing element  25  is sealingly engaged, by means of an annular seal  26 , against the lower edge  17  of the tubular member  16 , with the cup  27  isolated from the external environment and arranged below the nozzles of the dispensing head  14 . 
     According to the unique characteristic of the invention, the cup  27  defines a chamber configured for containing water generated by condensation at a temperature equal to or less than the dew point of ambient air. The humid environment thus generated inside the sealed volume delimited between the cup  27  and the tubular member  16  of the dispensing head  14  allows, when the dispensing head  14  is sealed by the closing device  20 , increasing the protection of the dispensing head thanks to the further reduction of the possibility of drying the products that are stationed at the ends of the various nozzles when no dosages are in progress. 
     The humidification system according to the invention, which as will be seen is automatic even if it can be supplemented by a manual refilling when necessary, envisages the intake of ambient air by means of one or more electric fans  28  positioned at the end of a forced duct  29  in communication with a suction mouth  30 . 
     Inside the forced duct  29  there is a cooling device consisting of a Peltier cell  32  and two heatsinks  32   a ,  32   b  arranged, respectively, on the cold side and on the hot side of the cell, of which at least the cold sink  32   a  is crossed by the airflow produced by the fan(s)  28 . The hot sink  32   b  can be crossed in series by the same airflow that passes through the cold sink  32   a , after the latter, in order to achieve a particular efficiency advantage due to the cooling effect of the airflow that hits the hot sink  32   b , by previously crossing the cold sink  32   a ; alternatively, depending on the embodiment, the hot sink  32   b  may have its own independent ventilation. In any case, the heat dissipation created by the hot sink  32   b  has the object of allowing the effective operation of the cell  32  and, therefore, of obtaining the appropriate amount of cooling of the cold sink. The function of this cooling system is to create water by condensing or frosting the humidity from the ambient air drawn into the duct  29  onto the cold sink  32   a  of the Peltier cell  32 . Frost instead of condensation may be due to the occurrence of an environmental condition such that the dew point is lower than the freezing point of the local atmospheric humidity, or it may be desired for functional reasons, even if the dew point is higher than said freezing point, in order to collect—per unit of time—a quantity of water from the atmosphere greater than that allowed by simple condensation; in the case of frost, the work cycle envisages a periodic shutdown step of the Peltier cell  32  and, therefore, the cessation of the cooling action of the cold sink  32   a , which allows, also thanks to the continued forced ventilation of ambient air through the forced duct  29 , liquefaction of the deposited frost. The collection of the water necessary for the humidification function takes place by making the water collected on the cold sink  32   a  drip by gravity into an underlying collecting tank  33 ; this tank  33  acts as a reserve of water, which is always available and the withdrawal of which can be activated/deactivated instantly at any time, regardless of the times associated with the start/stop transients of the condensation/frosting process. 
     In order for the condensation/frost on the cold sink  32   a  to take place, it is necessary that the sink itself is brought to and maintained at a temperature not exceeding the dew temperature (target temperature): the system can, therefore, provide a temperature and relative humidity sensor of the ambient atmosphere  34 , positioned in the first part of the forced duct  29  and designed to be able to constantly calculate the dew point, and a local sensor  35  of the target temperature, represented by the temperature of the cold sink  32   a  of the Peltier cell  32 , in order to close the control ring and automate the cooling process. 
     Inside the collecting tank  33  there are two level sensors  36 ,  37 , which allow signaling the reaching of a minimum level and a maximum level of water, respectively, in order to also automate the activation/deactivation process of the condensation system (suction and cooling). 
     The water stored in the collecting tank  33  is withdrawn, if necessary, by a pump  38  to be sent inside the cup  27  of the closing element  25 , in the steps in which this is in the proximal closing position of the dispensing head  14  of the dosing machine  10 . The delivery duct  39  of the pump  38  feeds the water from the tank  33  to the cup  27  without affecting the temperature of the dispensing head  14 , since the temperature of the water is substantially the ambient one, thanks to its more or less prolonged stay inside the collecting tank  33 , and to the passage through the pump  38  and relative ducts, all exposed to the ambient temperature. 
     The cup  27  is also equipped with a level sensor system  40 , necessary to complete the automation of the system, consisting of three electrodes  40   a ,  40   b  and  40   c  protruding downwards from the dispensing head  14 : the electrodes  40   b  and  40   c  protrude for different lengths and the electrode  40   a  protrudes for a length not less than that of the electrode  40   b , and configured so as to detect a maximum and a minimum level of the water present inside the cup  27 . The maximum level electrode  40   c  has a shorter length, the minimum level electrode  40   a  is longer than the maximum level electrode  40   c , and the common electrode  40   b  has a length equal to or less than the minimum level electrode  40   a . When the closing element  25  is in the proximal closing position of the dispensing head  14 , these three electrodes are protruded inside the cup  27 , evidently at different depths, thus resulting immersed or emerged relative to the water present therein. The liquid acts as a conductor and consequently opens or closes an electric circuit (at very low voltage) between minimum  40   a  and common  40   b  and/or between maximum  40   c  and common  40   b , depending on the level of the liquid present in the tank  27 . 
     The closed-loop control circuit of the cooling system according to the invention is represented in the block diagram of  FIG. 7 : an electronic control unit  41  activates (minimum detected level) or deactivates (maximum detected level) the pump  38  to send the liquid present in the tank  33  to the cup  27  of the closing element  24 . Activating the airflow through the Peltier cell  32  by means of the electric fan(s)  28  is operated by the control unit  41 , according to the signals coming from the level sensors  36 ,  37 , when the water level inside the collecting tank  33  falls below a threshold value, as well as possibly (depending on whether for producing water the logic is chosen of cooling below the dew point, or of forced frosting at the minimum temperature that can be reached by the system at maximum power) according to the signals from the temperature and humidity sensors  34 ,  35 . The control unit  41  activates the pump  38  when the water level inside said cup  27  detected by the sensors  40 , in turn, drops below a threshold value. 
     In all the steps wherein no dosage is in progress and the closing element  25  of the dispensing head  14  is closed on the dispensing head itself, the humid environment thus created inside the cup  27  due to the progressive and spontaneous evaporation of the water present therein hinders the drying of the products to be dosed stagnant in the nozzles of the dispensing head  14 , thus eliminating possible problems of obstruction of the ducts due to coagulation or solidification of the products themselves. The possible additional use of a non-illustrated heater, also integral with the dispensing head  14  and protruding inside the cup  27  until it is immersed below the water level when it is closed under the dispensing head  14 , may improve the system by accelerating the evaporation of humidity and reducing the time required to reach a satisfactory humidity content in the atmosphere inside the cup  27  itself. 
     A manual refilling duct  42  ( FIG. 3 ) can be provided to allow the introduction into the tank  33  of possible support additives such as disinfectants or anti-algae products, or possibly an extra manual refilling of water if required. 
     Finally, an optional version of the humidification system can be created, which does not include the water condensation device. This optional version with reduced automation may be proposed to meet two possible additional needs:
         to offer users the possibility of a cheaper version of the auto-humidification system, giving up the automatic production of water from the atmosphere,   to allow the adoption of liquids other than water for auto-humidification in those cases of use of dosing machines where water would produce undesirable interactions with the products to be dosed if drops of the products fell into the cup  27  of the closing element  20 .       

     In both these cases, the humidifying liquid can be manually inserted into the tank  33  through the refilling duct  42 . 
     Of course, the details of construction and the embodiments can be widely varied with respect to those described and illustrated, without thereby departing from the scope of the present invention as defined by the claims that follow.