Known dispensing or distributing machines for fluid products, such as for example dyes of different shade or color, able to be mixed with each other and/or added to a base substance in order to make up a varnish or a paint of a determinate color, comprise a plurality of delivery nozzles, variable in number, from a few to several dozen units, which are grouped together in a delivery head. Each delivery nozzle is connected to a corresponding tank containing a determinate dye and is governed by pump means which cause the selective delivery of the fluid product in a suitably chosen quantity, for example with the aid of an electronic processor.
Normally, in the use of said dispensing machines, it is necessary to deliver only a few fluid products at a time, and consequently the fluid products, which are not delivered frequently, remain in correspondence with the inactive nozzles and tend to dry out, creating problems when they are required to be delivered.
Moreover, there is also the disadvantage that the exsiccation of the fluid products in correspondence with the respective delivery nozzles leads to mistakes in measuring the quantities delivered, and can determine the introduction of coagulated, unmixable particles into the container that collects the finished product.
In addition, with the present situation in the market of dyes, it is necessary to use, ever more frequently, families of dyes that contain few or no solvents with a high boiling point, the so-called “high-boilers”, which generally consist of glycols, for environmental reasons and for reasons of pollution. Parallel to this situation, there has been an ever more frequent increase in the concentration of pigments, so that the fluid products have a high concentration of dry content, imposed by reasons of competition and made possible also by the ability, typical nowadays, of current dispensers to meter, accurately and repeatedly, ever smaller quantities of fluid products.
All this consequently leads fluid products in general, and dyes in particular, to dry out ever more quickly, and requires solutions able to solve this problem.
A mechanical device is known (also called “autocap”) applied to a delivery head provided with delivery nozzles and comprising a spongy cap which is able to selectively close the chamber made below the delivery nozzles. To be more exact, when all the nozzles are inactive, the chamber is closed and inside it a saturated or almost saturated environment of solvent and/or steam is formed. On the contrary, when at least one of the fluid products has to be delivered, the chamber is opened so that all the delivery nozzles are exposed to the atmosphere and can be activated. This solution alone is no longer sufficient to prevent exsiccation, because the time the delivery nozzles of the fluid products are exposed during the normal working of a dispenser allows the fluid products exposed, but not involved in the metering, to dry out, thus making it almost impossible to use them when they are subsequently required.
A device is also known to prevent the exsiccation of the delivery nozzles in a dispensing machine, wherein a continuous flow of humidified gas, taken from a tank containing a liquid, is introduced into a zone surrounding the delivery nozzles, by means of a pipe which ends parallel to the latter, as if it were one of them. This solution, however, has a series of problems, the most important of which is the tendency to an excessive concentration of liquid around the nozzles with a consequent saturation of the atmosphere and possible dripping of the fluid products. In other words, to prevent the exsiccation of the fluid products in the delivery nozzles there is a risk of exaggerating in the opposite direction, that is, by excessively fluidizing the fluid products themselves.
It is also known from JP-A-2001-009332 a coating apparatus comprising a plurality of coating material droplets of a coating material able to be diluted with water are attached to the surface of a board. A control system is provided to control the ambient conditions in the periphery of the nozzle tip end as to keep the relative humidity about 70% by supplying water to the ambient atmosphere from a humidifying mechanism on the basis of the sense data from a humidity sensor. Consequently, the coating material able to be diluted with water is prevented from deposition on the nozzle tip end in the dry atmosphere. However, this known apparatus is able to control only the relative humidity in the periphery of the nozzle tip end and to eventually increase the relative humidity by means of the humidifying mechanism, without the possibility to modify the other significant parameters which influence the exsiccation of fluid products.
One purpose of the present invention is to achieve a device and perfect a method to prevent the exsiccation of fluid products which will ensure the efficient and precise functioning of a dispensing machine for said fluid products, also for extended periods of inactivity of the delivery nozzles, preventing the products, in correspondence with the delivery nozzles, from deviating from the conditions of optimum fluidity in which they can be correctly delivered in the desired quantities.
Another purpose of the present invention is to achieve a device which is simple and economical to make and to use.
Another purpose of the present invention is to prevent the exsiccation of fluid products able to be delivered by a dispensing machine for said products possibly without using a protection cap to be arranged in correspondence with the delivery nozzles.
The present Applicant has devised, tested and embodied this invention, which brings a significant technical contribution to the state of the art, in order to obtain these and other purposes.