FIELD OF THE INVENTION

The invention relates to a proportional volumetric doser with improved dosing regulation.

KNOWN PRIOR ART

As is known, a proportional volumetric doser is a device that allows a first fluid, normally water, to be mixed with a second fluid, for example containing an additive or active ingredient for a variety of applications in the industrial and agricultural field.

Said dosers operate without the need to be connected to sources of electrical energy, but only due to the effect of the pressure and flow rate of the water.

Volumetric dosers can be used in a variety of applications in all sectors in which it is necessary to mix with precise proportions a main fluid with an auxiliary fluid or an additive. The main fluid may typically be water and the auxiliary fluid may be, according to the applications, oils, fertilizers, detergents, chemical products or products intended for the pharmaceutical industry in solution or the like according to the application sector of the doser.

Application sectors of dosers according to the present patent application may be the sector of mechanical processing, water treatment, fertilization and irrigation, washing cars, the food, chemical or pharmaceutical industry or the like.

Such dosers have a motor inside which a piston is made to translate.

The lower portion of the body of the motor has an inlet conduit for the main fluid and an outlet conduit for the mixed fluid.

Below the body of the motor there is a sleeve inside which a dosing chamber is provided for an auxiliary fluid to be mixed in a prefixed amount with the main fluid and the volume of which can be regulated manually as explained below.

The upwards and downwards movement of the motor piston is communicated to a small doser piston, where said small piston slides within the dosing chamber and sucks into said chamber the auxiliary fluid to be mixed with the main fluid.

Because, due to the effect of the mechanism described above, the stroke of the small doser piston is constant, the regulation of the quantity of auxiliary fluid that is first sucked and then injected into the motor body is performed precisely by regulating the volume of the dosing chamber. In particular, the regulation of the volume of the dosing chamber is performed by varying the axial position of a cylinder housed within the sleeve and provided with an axial cavity in which the doser piston slides.

Once the desired position of the cylinder has been determined, it is locked in position through a nut/counternut system that enables the locking in the axial direction of the cylinder with respect to the sleeve.

A problem of this solution consists of the fact that the clamping of the locking system determines relative movements of the cylinder with respect to the sleeve and therefore a variation of the volume of the dosing chamber, which makes the regulation of the quantity of auxiliary fluid to be mixed with the main fluid imprecise and inconvenient.

A further problem of such solution is the possibility of accidental loosening of the locking system, e.g. following improper regulation by the operator and/or due to vibrations and/or the presence of oil in the locking system.

An object of the present invention is that of obtaining improved precision in the determination of the quantity of auxiliary fluid to be mixed with the main fluid, through the creation of more stable and secure locking.

It is a further object of the present invention to obtain the aforesaid result in a rational and cheap manner.

BRIEF SUMMARY OF THE INVENTION

Such purposes are accomplished by the characteristics of the invention given in the independent claim. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.

In particular, the invention makes available a proportional volumetric doser comprising a motor, provided with an inlet conduit of a main fluid and an outlet conduit, and a pump adapted to supply an auxiliary fluid to the motor, which pump comprises a tubular sleeve inside which a cylinder is housed in which a small doser piston slides, mechanically connected to an output shaft of the motor, wherein an inner surface of the cylinder and the small piston partially define a dosing chamber of an auxiliary fluid to be mixed in the motor in a prefixed quantity with the main fluid, where said cylinder has a threaded outer portion that meshes with a threaded portion of a ring nut so that a rotation of the ring nut causes an axial translation of the cylinder and the variation of the volume of the dosing chamber, said proportional volumetric doser being characterized in that the sleeve comprises a locking system configured to mechanically lock the cylinder with respect to the tubular sleeve by creating a shape constraint.

Thanks to such solution the proportional volumetric doser enables quicker and more precise regulation of the volume of the dosing chamber, and therefore a regulation of the amount of secondary fluid to be mixed with the main fluid.

Another aspect of the invention envisages that the shape constraint is created by acting radially on an outer surface of the ring nut.

This aspect contributes to further improving the adjustment precision of the volume of the dosing chamber, as by acting radially on the ring nut to lock the position thereof, the position of the ring nut does not change, and therefore the axial position of the cylinder with respect to the sleeve is not changed.

Yet another aspect of the invention envisages the locking system being able to comprise a lever that has a portion provided with reliefs and/or grooves, adapted to be engaged with a corresponding outer portion of the ring nut, provided with reliefs and/or grooves configured to create a shape constraint with reliefs and/or grooves of the portion.

In this way, the locking system is particularly efficient and precise.

According to an aspect of the invention, the lever is housed in a seat of the tubular sleeve and comprises a hinge and a spring configured to keep the portion of the lever in contact with the outer portion of the ring nut.

In this way, the practicality of the doser is increased as the spring, when an operator does not act manually on the lever, automatically brings the portion provided with reliefs and/or grooves into contact with the outer portion provided with conjugated reliefs and/or grooves, locking the ring nut in the position reached.

An aspect of the invention, which may be independent or additional with respect to the presence of the spring acting on the lever, envisages that the doser can comprise a safety device selectively activatable between a first position, in which it generates on the lever a force such as to keep the portion of the lever in contact with the outer portion of the ring nut, and a second position, in which it allows radial clearance between said portions.

In this way the safety of the locking device is further improved. In particular, it can prevent the accidental unlocking of the lever.

For example, the safety device can be regulated in the intensity of the force generated on the lever when activated in the first position.

According to yet another aspect of the invention, the ring nut has an enlarged end that is housed in a conjugated annular hollow obtained in an enlarged end portion of the tubular sleeve with which a closing cover is associated, configured to keep the enlarged end of the ring nut in the annular hollow obtained in an enlarged end portion of the tubular sleeve.

Thanks to this solution the rotation of the ring nut causes the axial translation of the cylinder, in this way varying the volume of the dosing chamber and therefore the quantity of auxiliary fluid contained therein.

Another aspect of the invention envisages that the cylinder comprises a seat for receiving a one-way valve positioned at a distal end from the motor body.

This solution enables the emptying of the dosing chamber to be prevented.

Another aspect of the invention envisages a second one-way valve separated from the first one-way valve by a tube.

Thanks to this solution, the quantity of auxiliary fluid sucked by the small doser piston on a case-by-case basis can be controlled and blocked thus guaranteeing, during the operation of the doser, the constant supply of the auxiliary fluid to the inside of the dosing chamber. Furthermore, this aspect allows the emptying of the tube when not in use to be prevented.

According to a further aspect of the invention, there may be at least one bleed hole.

This characteristic improves the versatility of the doser, as it allows optimal washing more quickly with respect to devices of the prior art. Furthermore, such characteristic allows mixed fluid to be collected in order to perform analyses thereon without the need to disassemble the doser.

According to an aspect of the invention, the motor can comprise a body inside which a piston slides connected to the output shaft of the motor, which divides the internal volume of the body of the motor into a first chamber in communication with the inlet conduit of the main fluid and a second chamber in communication with the outlet conduit, where the first and the second chamber are placed in communication with one another by means of a system of valves associated with the piston and activatable for placing the piston in movement.

