Description

A liquid dispensing unit-

Technical Field

The present invention relates to a unit for dispensing liquids. The invention finds application particularly in the art field of machines for filling containers with a variety of substances, for example liquid food products such as milk or fruit juices, and non-food products such as mineral lubricating oils, detergents, and the like.

Background Art

Such filling machines comprise a tank supplying one of the aforementioned liquid substances and equipped at the bottom with a plurality of dispensing units, each connectable to the mouth of a relative container.

Each dispensing unit comprises a nozzle presenting a duct and, slidable along the axis of the duct, a valve element rigidly associated with the bottom end of a rod in which motion is induced by a linear actuator consisting of a pneumatically operated cylinder.

According to practical experience, dispensing units of the type in question, and especially units incorporated into filling machines capable of operating at high output speeds, cannot be guaranteed to fill containers with suitable and repeatable precision.

This is a drawback attributable to the relatively sluggish response of the aforementioned actuators, and consequently the valve element, when piloted to open and close the nozzle, usually by devices monitoring the weight of the containers.

A further drawback associated with dispensing units representative of the prior art is that they afford limited flexibility; that is to say, they cannot be adapted for use with liquids having dissimilar properties, and in particular,

adapted for use both with foamable liquids and with viscous liquids, except by making significant structural modifications.

Normally, in the case of foamable liquids, containers receive a jet dispensed at a relatively low flow rate, in particular during the initial stage of the fill, so as to avoid excess foaming and spillage of the product, whereas in the case of viscous liquids, the flow rate of the jet needs to be relatively high in order to overcome the resistance created by the viscosity of the product.

The object of the invention is therefore to overcome the drawbacks in question by providing a unit for dispensing liquids that offers precision and flexibility, and is of simple embodiment.

Disclosure of the Invention

The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which:

- figure 1 is a side view of a machine for filling containers with liquid substances, equipped with a dispensing unit according to the present invention; - figure 2 is an enlarged sectional view of a dispensing unit as in figure 1, shown in a first operating configuration;

- figure 3 shows the dispensing unit of figure 2 in a second operating configuration;

- figure 4 is a schematic and sectional view of a dispensing unit according to the present invention, illustrated in a second embodiment.

With reference to figure 1, numeral 1 denotes a filling machine, in its entirety, suitable for dispensing liquid or powder products into containers 2, each presenting a filler mouth 3.

Reference is made in the present specification to a machine by which containers are filled with a liquid product.

The machine 1 comprises a carousel 4 set in rotation about a vertical axis A.

The carousel 4 comprises a disc 5 with peripheral pedestals 6 supporting single containers 2 and, associated with each pedestal 6, means schematized as

a block denoted 7, by which the container 2 is weighed during the filling step.

The filling step occurs along a path extending between an infeed station 8, at which empty containers 2 are taken up, and an outfeed station 9 at which the filled containers 2 are released from the carousel 4 by way of a transfer unit, not illustrated in the drawings.

The machine 1 comprises a tank 10 containing the aforementioned liquid product, and, aligned vertically above each pedestal 6, a dispensing unit 11 mounted to the carousel 4, connected to the tank 10 by way of an outlet duct 12 and caused to engage the neck or mouth of a respective container 2 during the passage of the selfsame container between the infeed station 8 and the outfeed station 9.

Referring in particular to figure 2, the single dispensing unit 11 is substantially cylindrical in shape, centred on a vertical axis B, and comprises a nozzle 13 at the bottom from which the product is released, surmounted and operated by an actuator assembly 14.

The dispensing unit 11 also presents a box element 15, mounted above the actuator assembly 14, in which a monitoring and control module 16 is housed.

The nozzle 13 comprises a cylindrical sleeve 17 serving to establish a flow duct 18 of funnel-like embodiment that extends along the axis B and is connected at the top, by way of a tubular coupling 19 aligned on a horizontal axis, with the aforementioned outlet duct 12 of the tank 10.

The duct 18 presents a dispensing outlet 20 at the bottom and houses a valve element 21, attached to a stem 22, capable of movement between a lowered position (figure 2) and a raised position (figure 3) in which the outlet 20 is closed and open, respectively.

The valve element 21 and the inside surface of the duct 18 are contoured in such a way that the product flow will assume predetermined shape, velocity and pressure characteristics during the course of the filling step.

The actuator assembly 14 operating the valve element 21 comprises a hollow cylindrical body 23 coaxial with the duct 18, isolated from the selfsame

duct by a wall consisting in a flexible diaphragm 24, and enclosed uppermost by a bottom wall 25 of the box element 15 housing the monitoring and control module 16.

The cylindrical body 23 is made up of three vertically stacked annular elements, denoted 26, 27 and 28 from bottom to top, secured one to another by fastening means consisting of bolts 29 contained within the wall thickness of the three annular elements 26, 27 and 28.

Located internally of and coaxial with the cylindrical body 23 is a rod 30 operating the valve element 21, secured by its bottom end to the top end of the aforementioned stem 22 at a point coinciding with the flexible diaphragm 24.

The body 23 also houses a disc 31, located between the bottom annular element 26 and the intermediate annular element 27, through which the rod 30 is insertable together with interposed axial slide means 32.

The disc 31 and the flexible diaphragm 24 combine to delimit a first fluid- tight enclosure, denoted 33.

The axial slide means 32 are associated permanently with a coil spring 35 ensheathing the rod 30, interposed between the selfsame slide means 32 and a plate 34 offered in contact to the flexible diaphragm 24, and providing spring bias means by which the valve element 21 is maintained in the position that closes the duct 18.

The intermediate annular element 27 and the top annular element 28 are separated by a flexible wall 36 anchored centrally to the rod 30 and peripherally to the cylindrical body 23.

The disc 31 and the flexible wall 36 combine to delimit a second fluid-tight enclosure, denoted 37.

The bottom wall 25 of the box element 15 and the flexible wall 36 combine to delimit a third enclosure 38 internally of the top annular element 28.

The top end of the rod 30 extends beyond the flexible wall 36 in axial alignment with a travel limiting element 39 anchored to the bottom wall 25 of the box element 15, which projects into the third enclosure 38 and, in the

example of figure 2, is separated by a predetermined distance from the free end face 30a of the rod.

The box element 15, which presents an essentially parallelepiped appearance, is delimited laterally by side walls 40 and enclosed uppermost by a lid 41.

The box element 15 contains a solenoid valve 42 supplied with electrical power by way of a cable 43 and connected by way of a hose 44 to a source of compressed air, not illustrated.

The solenoid valve 42 is connected on the outlet side, by way of hoses 45 and 46 inside the box element 15, to a first passage 47 and a second passage 48 formed within the wall thickness of two annular elements 27 and 28 making up the cylindrical body 23 and emerging into the intermediate enclosure 37 and the top enclosure 38, respectively.

The hoses 45 and 46, the first passage 47 and second passage 48 establish pneumatic connection means 100 associated with the dispensing unit 11.

In operation, starting from a condition in which the nozzle 13 is closed

(figure 2), a master controller, schematized as a block denoted 49, will general a signal coinciding with the entry of a container 2 at the infeed station 8, by which the solenoid valve 42 is piloted to connect the second enclosure 37 with the source of compressed air via the first passage 47.

With reference to figure 3, the pressure increase internally of the second enclosure 37 causes the flexible wall 36 to deform and lift, overcoming the resistance of the coil spring 35 and pulling the valve element 21 upward together with the rod 30, with the result that the nozzle 13 opens. The opening distance of the nozzle 13 is governed by the travel limiting element 39.

In this situation, and with the carousel 4 in rotation, the operation of filling the container 2 proceeds, monitored by the aforementioned weighing means 7, which conventionally will be of a type using load cells. Once the completion of the filling step is indicated by the weighing means 7,

the master controller 49 pilots the solenoid valve 42 to release the pressure from the second enclosure 37, whereupon the nozzle 13 closes through the action of the coil spring 35, which forces the flexible diaphragm 24 downwards, causing the stem 22 to shift toward the aforementioned starting condition in which the dispensing outlet 20 is closed.

To assist the action of the spring 25 and speed up the closing movement of the nozzle 13 in response to the control signal, the third enclosure 38 is connected to the source of compressed air by way of the relative passage 48 and the solenoid valve 42; this causes the selfsame third enclosure 38 to pressurize, deforming the flexible diaphragm 36 and forcing it downwards.

The dispensing unit 11 illustrated in figure 4 differs from the unit described thus far, inasmuch as the valve element 21 is able to assume two different open positions.

In this instance, the actuator assembly 14 comprises not three but five enclosures denoted 50, 51, 52, 53 and 54, viewed from the bottom upwards, interposed between the flexible diaphragm 24 and the bottom wall 25 of the box element 15.

The five enclosures 50, 51, 52, 53 and 54 are delimited laterally by a cylindrical body 55 constructed substantially as described above, with the addition of two further annular elements 56 and 57 interposed between the intermediate annular element 27 and the top annular element 28, establishing the enclosures denoted 52 and 53 respectively.

In the case of the enclosures denoted 50 and 51, the same considerations apply respectively as for the enclosures 33 and 37 described above, and accordingly, the walls and mechanical components are denoted by the same numerals as in figures 2 and 3.

The first additional enclosure 52 is located between the flexible diaphragm 36 and a disc 58, the second additional enclosure 53 between the disc 58 and a further flexible wall 59, and the uppermost enclosure 54 between the flexible wall 59 and the bottom wall 25 of the box element 15.

Still referring to the example of figure 4, the rod operating the valve element, denoted 60, comprises a lower first portion 61 rigidly associated with the stem 22, and an upper second portion 62.

The upper second portion 62 of the rod 60 passes through the disc denoted 58 together with interposed slide means 63, similar to the slide means 32 first mentioned, extending beyond the flexible wall 59 in axial alignment with the aforementioned travel limiting element 39.

The rod 60 is deployed with the bottom end 62a of the second portion 62 and the top end 61a of the first portion 61 located internally of the first additional enclosure 52, coupled one to another.

More exactly, the end 61a of the first portion 61 is free to slide axially in a cylindrical cavity 64 afforded by the second portion 62, between an upper limit position denoted 65 and a lower limit position denoted 66.

In the example of figure 4, the box element 15 houses both the solenoid valve 42 mentioned above, and a further solenoid valve 67 connected to the second additional enclosure 53 by way of a passage 68 in the two annular elements 28 and 57 uppermost.

In operation, starting from the situation of figure 4, in which the first portion

61 of the rod 60 occupies the aforementioned lower limit position 66 relative to the second portion 62, the operation of filling the container 2 comprises a first step during which the master controller 49 pilots the first solenoid valve 42 to connect the enclosure denoted 53 to the source of compressed air, with the result that the flexible wall 59 deforms and the valve element 21 opens at a first position corresponding to a first specified flow rate of the liquid product. In a second step of the filling operation, the master controller 49 pilots the second solenoid valve 67 to connect the enclosure denoted 51 to the source of compressed air, whereupon the relative flexible wall 36 will deform and draw the stem 22 into the upper limit position of the valve element 21, determining a second open configuration of the nozzle corresponding to a second specified flow rate of the liquid product, higher than the first.

The relative duration of the two filling steps, as the container 2 advances from the infeed station 8 to the outfeed station 9, is supervised by the master controller 49 according to the characteristics of the dispensed liquid.

More exactly, in the event that the liquid product is highly foamable, the duration of the first step, coinciding with the first raised position of the valve element 21, will be longer that of the second step; where the liquid is highly viscous, the opposite will be the case.

In extreme cases where the viscosity of the liquid is particularly high, the control signal piloting the valve element 21 to assume the second open position will be generated substantially at the same moment as the passage from the closed position to the first open position.

The bottom enclosure 33 or 50 is furnished with a sensor 69 serving to detect the presence of liquid in the selfsame enclosure 33 or 50, which would indicate a failure of the flexible diaphragm 24. In the event of such a failure, advantageously, the flexible diaphragm 24 need not be replaced immediately, since the mechanical components accommodated internally of the enclosure 33 or 50 will be fashioned from stainless steel and the adjoining enclosure 51 or 37 is isolated from the bottom enclosure 33 or 50 by the disc 31, which is mounted internally of the cylindrical body 23 together with interposed seals 70.

It will be seen that the dispensing unit 11 can be removed easily and swiftly from the filling machine 1 by unfastening connection means denoted 71, allowing its transfer to another machine, or its replacement for example in the event of mechanical failure. Similarly, as will be evident from the foregoing description, the modular structure of the actuator assembly 14 is such that the unit of figures 2 and 3 can be converted simply and speedily to assume the configuration of figure 4 by fitting the additional annular elements 56 and 57.

Also, reference notches will ensure that the various annular elements are assembled in the correct angular positions one relative to another, with the

parts affording the air passages and the holes for the fastening bolts properly aligned.