A FILLING VALVE

TECHNICAL FIELD AND BACKGROUND ART. The present invention relates to a filling valve. The present invention relates in particular to the food sector, in which filling machines are used, i.e. machines for filling a plurality of containers with a liquid product.

Filling machines generally comprise a carrousel provided with a plurality of filling valves, each of which is activated and deactivated during the motion of the valve itself integrally with the carrousel.

Each filling valve ordinarily comprises a shutter, movable between an open position and a closed position and able to assume also an intermediate position to throttle the flow of product introduced into the containers during the filling operation. With regard to filling valves with the shutter movable between an open position, a closed position and an intermediate position, known technical solutions provide for the use of a first and a second pistons, movable in a housing along their own longitudinal axis. The first piston is connected to the shutter and it is movable between a closed position, at a lower end stop and an open position, at an opening end stop. The second piston is movable between a position of non interference with the first piston and a second position, in which it defines an end stop for the first piston, when the first piston (integrally with the shutter) is in the intermediate position. In known solutions, at least the first piston is double action, so that it can

be moved both in the direction of opening and in the direction of closing. Moreover, prior art solutions provide constraining elements to limit the stroke of each of the two pistons. In particular, there are a first and a second constraining elements to limit the stroke of the second piston and corresponding constraining elements to limit the stroke of the first piston (in the open and closed position).

To optimise the filling according to the product to be poured and of the containers to be filled, the intermediate position of the shutter may be varied. In this light, known technical solutions provide that one of the constraining elements of the first piston is adjustable, to displace an end stop of the first piston. In other technical solutions, one of the constraining elements of the second piston is adjustable, to displace an end stop of the second piston. However, known technical solutions entail some limitations.

First of all, they do not allow to efficiently adjust the excursion of the first piston or of the shutter, from the open position to the closed position and from the closed position to the intermediate position. Moreover, prior art technical solutions do not allow to offset construction tolerances during the adjustment operation, with the consequence of introducing errors in the adjustments of the excursions of the shutter. A further drawback is that not all constraining elements can be adjusted independently, this preventing a complete and correct adjustment / calibration of the valve. DISCLOSURE OF THE INVENTION.

An object of the present invention is to eliminate the aforesaid drawbacks and to make available a filling valve with shutter having three positions that are precisely adjustable, with the capability of totally offsetting the effect of machining tolerances. Said object is fully achieved by the valve of the present invention, which is characterised by the content of the appended claims and in particular in that each of said first and second constraining element is adjustable independently of the other to displace axially the corresponding end stop of the second piston. According to another aspect of the present invention, the filling valve preferably comprises a spring positioned in the housing of the valve body in such a way as to exercise a thrusting action on the first piston in the direction of opening, with the advantage of using single action pistons, with no need to use double action pistons. According to another aspect of the present invention, said first and second constraining elements can be adjustable in such a way as to lock the second piston in contact with the first piston, when the latter is in a closed position of the valve; this enables, advantageously, to offset completely the play due to machining tolerances. BRIEF DESCRIPTION OF DRAWINGS .

These and other characteristics shall become more readily apparent from the following description of a preferred embodiment, illustrated purely by way of non limiting example in the accompanying drawing tables, in which: - figure 1 shows a sectioned view of a valve according to the present

Invention;

- figure 2 shows the valve of figure 1, in an operative condition of closure;

- figure 3 shows the valve of figure 1, in an operative condition of opening;

- figure 4 shows the valve of figure 1, in an operative condition of throttling;

- figure 5 shows the valve of figure 1, in a first adjustment step;

- figure 6 shows the valve of figure 1, in a second adjustment step; - figure 7 shows the valve of figure 1, in a third adjustment step;

- figure 8 shows the valve of figure 1, in a fourth adjustment step;

- figure 9 shows the valve of figure 1, in a fifth adjustment step;

- figure 10 shows a lateral view of the valve of figure 1. BEST MODE FOR CARRYING OUT THE INVENTION. In the figures, the reference number 1 designates a filling valve according to the present invention.

The valve comprises a shutter 2 able to open or close a conduit 3 for the passage of the products to be introduced into the container during the filling operation. The reference number 4 designates a first piston, having a first end 5 and a second end 6. The first piston 4 is movable in a housing at least partially defined within a valve body 7.

The shutter 2 is fastened to the first end 5 of the first piston 4 and moves integrally therewith. The reference number 8 designates a second piston, also movable in said

housing.

Said housing develops along a longitudinal axis. The first piston 4 and the second piston 8 are movable axially along said longitudinal axis. Moreover, the first piston 4 and the second piston 8 are aligned along said longitudinal axis, so that the first piston 4 is interposed between the shutter 2 and the second piston 8.

In this way, an end 9 of the second piston 8 interacts with the second end 6 of the first piston 4 to define an end stop for the first piston 4. The reference number 10 designates a spring, positioned in said housing in such a way as to exert a thrusting action on the first piston 4 in the direction of opening. Said direction of opening corresponds to a movement of the shutter 2 such as to open the conduit 3; vice versa, an opposite direction of closure corresponds to such a movement of the shutter 2 as to close the conduit 3. Note that the spring 10 can be replaced by any other return means, i.e. any actuating means active on the first piston 4 to actuate it in the direction of opening.

The valve 1 also comprises a first actuator, operatively active on the first piston 4 to actuate it in the direction of closure and a second actuator operatively active on the second piston 8 to actuate it in the direction of closure.

Said actuators (not shown in the figures) are preferably pneumatic and they are known to those skilled in the art. However, other kinds of actuators may be used (e.g., actuators constituted by an electric motor combined with a reduction gear).

In the preferred embodiment illustrated, the first pneumatic actuator is connected to a first inlet 11, through which it inserts the fluid for actuating the first piston 4; the second pneumatic actuator is connected to a second inlet 12, through which it inserts the fluid for the actuation of the second piston 8. The second inlet 12 is in communication with said housing in which slides the second piston 8 through a hole having substantially radial development, relative to said longitudinal axis defined by the pistons (4 e 8) and by the housing. In the preferred embodiment illustrated, the second piston 8, originally, internally defines a passage 13 for the actuating fluid of the first piston 4, injected through the first inlet 11 by the first actuator. The stroke of the first piston 4 determines the (maximum) section for the passage of the filling fluid flowing out of the conduit 4, in the open position of the valve 1. This stroke is defined by an end stop for the first piston 4 in the direction of opening.

In the valve 1, said maximum opening end stop for the first piston 4 is constituted, originally, by the second piston 8. In this light, note that the housing in which the first and the second piston move, originally, lacks abutments or other means able to limit the stroke of the first piston 4 in the direction of opening.

The stroke of the second piston 8 is delimited, in the direction of opening, by a first constraining element 14 and, in the direction of closing, by a second constraining element 15. When the first constraining element 14 acts, i.e. when the second piston 8 is at the end stop in the direction of opening, the second piston 8 itself,

originally, defines (with its end 9) an end stop for the first piston 4, limiting its stroke in the direction of opening.

When the second constraining element 15 acts, i.e. when the second piston 8 is at the end stop in the direction of closing, it defines (with its end 9) an intermediate position for the first piston 4, limiting the end stop in the direction of opening such that the valve is throttled (i.e. with the shutter 2 in an intermediate position between the position of total opening and the position of closure). Note that the expressions "direction of opening" and "direction of closure" always refer to the direction whereby the shutter opens or closes the valve, regardless of whether said expressions are referred to the first or to the second piston, since the pistons are aligned and movable along the same direction. In the preferred embodiment illustrated, the first constraining element 14 is associated to the valve body 7. In particular, the first constraining element 14 comprises its own bushing 16 associated to the valve body 7 such as to be movable relative thereto along said longitudinal axis. For example, the bushing 16 is coupled to the valve body 7 by means of a threaded coupling. Moreover, the first constraining element 14 preferably comprises its own ring nut 17 interacting with the bushing 16 to lock it in a desired position. In this way, the position of the first constraining element 14 is adjustable in the longitudinal direction of actuation of the pistons 4 and 8. Also in the preferred embodiment illustrated, the second constraining element 15 is associated to the second piston 8. In particular, the second

constraining element 15 comprises its own bushing 18 associated to the second piston 8 such as to be movable relative thereto along said longitudinal axis. For example, the bushing 18 is coupled to the second piston 8 by means of a threaded coupling. Moreover, the second constraining element 15 preferably comprises its own ring nut 19 able to lock the bushing 18 in a desired position. In this way, the position of the second constraining element 15 is adjustable in the longitudinal direction of actuation of the pistons 4 and 8. Therefore, the end stops of the second piston 8 are, originally, both adjustable in the longitudinal direction of actuation of the pistons 4 and 8.

Operatively, the valve 1 according to the present invention operates as follows. When the first shutter is active, it actuates the first piston 4 in the direction of closing overcoming the resistance of the spring 10; therefore, the valve is in the closed position, as shown in figure 2. In this case, the second actuator is preferably, but not necessarily, inactive. When both actuators are inactive, the first piston 4 is subjected to the action of the spring 10, which actuates it in the direction of opening; the first piston 4 in turn acts on the second piston 8 actuating it in the direction of opening, until the first constraining element 14 intervenes to stop its stroke. In this situation (shown in figure 3) the valve 1 is in the open position. In this situation, the opening of the shutter 2 is determined by the first constraining element 14, which defines the end stop for the second piston 8 (and consequently also for the first piston 4) in the

direction of opening. Therefore, adjusting the position of the first constraining element 14, it is possible to adjust the opening of the valve 1 in the open position (maximum opening).

When the first actuator is inactive and, at the same time, the second actuator is active, the second actuator actuates the second piston 8 in the direction of closing (overcoming the resistance of the spring 10 that acts on the second piston 8 indirectly, through the first piston 4). In this situation, the second constraining element 15 is active on the second piston 8, limiting its stroke in the direction of closing. Therefore, the valve 1 is in the intermediate position (i.e., of throttling), as shown in figure 4. In this operative configuration, the first piston is subjected to the action of the spring 10, which actuates it in the direction of opening until the second end 6 of the first piston 4 is in contact with the end 9 of the second piston 8, which defines an end stop for the first piston 4 in the direction of opening. Therefore, adjusting the position of the second constraining element 15, it is possible to adjust the opening of the valve

1 in the throttling position.

It should be noted that the valve 1 is originally configured so that said first and second constraining element are both adjustable. Moreover, said constraining elements are originally adjustable independently from each other.

The present invention achieves some important advantages. In the first place, the valve 1 enables to adjust the opening of the shutter

2 both in the position of opening and in the position of throttling, acting on the first or on the second constraining element, respectively, to limit

the stroke of the second piston 8.

Moreover, the present invention enables completely to offset, during the adjustment operation, the influence of the machining tolerances of the pistons, thereby assuring a particularly precise and accurate adjustment. Said total offset of the machining tolerances entails the application of an original method, as described hereafter.

Note also that the present invention is advantageous because it is particularly simple and economical to obtain. It enables to construct a filling valve with three positions (totally closed, totally open and throttled) using two pistons, each piston being of the single action type, i.e. able to be operated by actuation means (e.g., pneumatic) in a single direction of actuation. On the contrary, in prior art solutions at least one of the two pistons was double-action (i.e. movable in both directions). In this way, the present invention allows an additional cost reduction, because it does not necessarily require the presence of a three-way valve to feed the actuation means of the pistons.

A description follows of the method for adjusting / preliminarily calibrating the valve 1 and in particular its constraining elements 14 and 15, to define the maximum opening and the throttled opening. Said method comprises the following steps.

In a first step (figure 5), the valve 1 is managed in the closed configuration, i.e. with both actuators inactive. In this configuration, said first step provides for displacing the first constraining element 14 and the second constraining element 15 in the direction of closing, such that: - the first constraining element 14 is in contact with the second piston 8,

locking it against the first piston 4, which is in the closed position; - the second constraining element 15 is in contact with the second piston 8.

This configuration is illustrated in figure 5.

5 In a second step, the first constraining element 14 is positioned at a predetermined distance relative to the position assumed in the configuration of the first step. In other words, in the second step the first constraining element 14 is displaced in the direction of opening by a predetermined quantity (corresponding to the opening of the shutter 2 in io the throttled position).

According to the preferred embodiment illustrated, the second step in turn comprises two intermediate steps.

In a first intermediate step of the second step, the bushing 16 of the first constraining element 14 is displaced in the direction of opening (to this i5 intermediate step corresponds the configuration of the valve 1 illustrated in figure 6).

In a second intermediate step of the second step, the gear nut 17 of the first constraining element 14 is displaced in the direction of opening (to this intermediate step corresponds the configuration of the valve 10 illustrated in figure 7).

In a third step, the second constraining element 15 is positioned at a predetermined distance relative to the position assumed in the configuration of the second step. In other words, in the third step the second constraining element 15 is displaced in the direction of opening5 by a predetermined quantity (corresponding to the opening of the shutter

2 in the open position).

According to the preferred embodiment illustrated, the third step in turn comprises two intermediate steps.

In a first intermediate step of the third step, the bushing 18 of the second constraining element 15 is displaced in the direction of opening (to this intermediate step corresponds the configuration of the valve 1 illustrated in figure 8).

In a second intermediate step of the third step, the gear nut 19 of the second constraining element 15 is displaced in the direction of opening (to this intermediate step corresponds the configuration of the valve 1 illustrated in figure 9).

Note that the second and the third step can be performed in reversed order. On the contrary, the first step must necessarily be performed first.

In this light, note that said first and second constraining elements can be adjustable in such a way as to lock the second piston 8 in contact with the first piston 4, when the latter is in a closed position of the valve 1, to offset completely the influence of machining tolerances. This configuration corresponds to the first adjustment step.