EP0626340A1

EP0626340A1 - A valve filler group for container filler machines

Info

Publication number: EP0626340A1
Application number: EP94830131A
Authority: EP
Inventors: Yvon Van Neste
Original assignee: Procomac SpA
Current assignee: Procomac SpA
Priority date: 1993-05-25
Filing date: 1994-03-22
Publication date: 1994-11-30
Also published as: ITPR930024A1; ITPR930024A0; IT1265531B1

Abstract

A filler valve group comprises a device for activating an obturator (12) of a liquid flow pipe (1), which obturator (12) mechanically closes the liquid flow pipe (1) independently of filler machine speed. At the same time a hydraulic closure of the liquid flow pipe (1) is achieved by a filler liquid reaching a prefixed level, whereat the liquid contacts a lower end of a liquid return pipe (19).

Description

The invention relates to a valve filler group for container filler machines.
Isobarometric machines are well-known having filler valve groups provided with two coaxial pipes, one for the liquid and another for the gas (normally carbon dioxide or oxygen), both usually kept closed by the internal filler tank pressure, which is greater than the elastic spring force acting in favour of opening.
When a hermetic coupling has been achieved between the container mouth and the lower part of the filler valve group, a mechanical positioner opens the gas valve and brings the container to the same pressure as the gaseous phase of the filler tank, known as the isobarometric phase. Once equality of pressure has been reached, the liquid valve spontaneously opens following the spring action and the filling operation begins, the air in the container exiting through a return pipe.
The filling operation stops hydraulically when the liquid level in the container touches the lower end of the return pipe.
The liquid valve stays mechanically open up until it contacts with a command moving a mechanical positioner which in its turn closes both the liquid valve and the gas valve. Subsequently the pressure inside the container is expelled into the atmosphere through a small snift valve.
In such fillers, in the absence of a container or when a container explodes, the liquid valve closes automatically, notwithstanding the antagonist spring pressure, because of the pressure difference between the tank and the outside environment: in this way undue waste is avoided.
Delay in closure of the liquid valve, when the closure is hydraulic, can be significantly long, especially when the filler slows or stops, because the air closed in the container tends to invade the liquid valve, causing changes in filler levels, and the liquid also tends to rise internally of the return pipe up to a level which is equal to that of the tank level, obeying the principle of communicating chambers.
To avoid such air invasion, air barriers have been used, such as for example a syphon passage or a metal net: in traditional filler machines, to solve the problem of liquid flow-back, the liquid is usually blown out of the return pipe when the valve group is between the exit star conveyor and the entry star conveyor, that is at the end of each filling operation and before the next.
A further drawback of such valve groups is that they need to operate at rather a high pressure (about half a bar).
The principal aim of the present invention is to obviate the above-mentioned drawbacks by providing a filler valve group which is simple to construct and which affords considerable filler level precision, as it requires only a low pressure level to function.
A further aim is to guarantee mechanical closure of the liquid valve at the same time as the hydraulic closure which occurs when the desired level has been reached, independently of the machine rotation speed.
A still further aim is to regulate the filler delivery according to the shape of the containers to be filled, as well as providing a way to release the air in the containers through a different channel to the liquid-contacting return pipe.
The above aims are all fully attained by the filler valve group of the invention, as characterised in the following claims, and especially in that it comprises a device permitting the mechanical closure of the liquid pipe at the same time as the hydraulic closure caused by the liquid reaching a predetermined level, whereat the liquid contacts the air return pipe.
Further characteristics and advantages of the present invention will better emerge from the detailed description that follows, of a preferred but non-exclusive embodiment here illustrated in the form of a non-limiting example in the accompanying drawings, in which:

figures 1 and 2 show, in vertical section, the filler valve group respectively in the closed position and the open position of the liquid flow valve;
figure 3 shows, in vertical section, the valve group according to a further embodiment of the invention.

With reference to the figures, 1 denotes a liquid flow pipe containing a coaxial gas pipe 9 terminating below a return pipe 19 destined to penetrate inside an empty container 10 and, with its lower end, define the desired level which the liquid will reach.
The container 10 filling operation begins when a hermetic couple has been obtained between the container 10 and a gasket 15 of a centring element 11, of known type, which is associated to the valve group.
3 denotes a membrane connecting the pipe 1 to the pipe 9, which latter pipe 9 is slidable with respect to the former, between an upper position (see figure 1) and a lower position (figure 2), where a support 14 of the membrane 3, solid to the gas pipe 9, leans against an endrun stop constituted by a washer 8.
The gas pipe 9 is externally provided with a swelling functioning as an obturator 12 for the liquid flow pipe 1. The gas pipe 9 and the obturator 12 are normally kept forced upwards against a gasket 13 solid to the liquid flow pipe 1 so as to close it due to the effect of the different extensions of two surfaces on which the pressure present in the liquid flow pipe 1 is exerted. Said internal pressure in the liquid flow pipe 1, maintained by connection with an excess pressure channel 2, pushes the mobile gas pipe 9 upwards due to the fact that the upwards force F up = p* Sdown is greater than the sum of the gas pipe 9 weight, the force exerted on the column of liquid present between pipes 1 and 9, and the downwards force Fdown = 'p* Sdown, the surface of application of the force on the lower face of the membrane being much greater (preferably four times greater) than the corresponding Sdown in the obturator 12 zone.
With the obturator 12 in closed position, the pressure in a channel 4 at atmospheric pressure since communicating with the external atmosphere acts on the upper face of the connection membrane 3.
5 denotes a conventional type button valve, pressed by an opening skate (not illustrated) when the container 10 has been hermetically coupled with the gasket 15 of the centring element 11.
When the valve is opened the pressure in a chamber above the membrane 3 and the pressure in the container 10 are brought to the same level as the pressure in the channel 2. The valve 5 places the channel 2 in communication with the chamber 16.
The gas pipe 9 descent falls, its weight together with the weight of the liquid column no longer being antagonised by the pressure on the membrane 3. The liquid passage is opened and the filling operation begins, during which the air expelled from the container 10 keeps chamber 16 and not chamber 2 under pressure, as the button of the valve 5 is released at the end of the opening skate: the air flow, before reaching the channel 4, is choked in the passage through a calibrated orifice 6 made in a stem 7 of the valve group.
When the container 10 level reaches the lower end of the return pipe 19, the air flow from the container 10 to the valve group is stopped while the release of the air container in the chamber 16 continues towards the channel 4. The chamber 16 returns to atmospheric pressure, causing an almost immediate closure of the liquid flow obturator 12.
The connection membrane 3, together with the chamber 16 and the special configuration of the upper zone of the valve group, constitutee an activation device of the obturator 12 of the liquid pipe, causing its mechanical closure independently of the filler rotation speed, at the same time as causing the hydraulic closure of the pipe due to the liquid reaching a preestablished level in the container 10. The connection membrane 3, according to a further embodiment of the invention (not illustrated) could be substituted by a piston with a slidable gasket inside the liquid flow pipe 1 above the washer 8.
17 denotes a cam which brings the stem 7 into various angular positions, each said position corresponding to a special diameter of the calibrated orifice 6, so that each stem position corresponds to a particular filling speed. This can be useful when, for example, containers are being filled with gassy liquids, where the filling speed must be lower to avoid a build-up of froth.
In a stem 7 angular position used during valve group cleaning, the orifice is the of same diameter as a pipe 18 connecting it with the channel 4.
In the absence of pressure in the channel 2, the obturator 12 stays open and it is not possible to fill a channel 20 with the liquid for the contemporaneous opening of all of the filler valve groups. To obviate this, during the starting-up phase,the passage between the channel and the channel 2 (not illustrated) is closed by a valve (not illustrated), the channel 2 is pressurised, causing the obturator 12 to close, the channel 20 is filled with the liquid and the passage between the channel 20 and the channel 2 is closed.
The filler valve group of the invention is applicable both in conjunction with gassy and still liquids. In the case of gassy liquids, the pressure of channels 2 and 20 is typical of gassy liquids.
With reference to a further embodiment of the invention, illustrated in figure 3, 21 denotes a level sensor for the presence of liquid and also able to break the electric circuit formed between the sensor and a metal element 22 fixed below the pipe 9. In the illustrated example, the metal element 22 is bell-shaped, but it could be conformed with two metal bars or tongues.
Through an amplifier, the circuit breaker signal activates a solenoid valve 24 wich increases the air flow section towards the channel 4 and causes the closure of the liquid flow pipe.
The embodiment of figure 3 is particularly suited to filling containers with gassy liquids, since the sensor 21 is sensitive to the presence of liquid but not froth, so that precision of level reading is guaranteed.
The valve group is easy to clean in both flow directions, and is operative even in functioning environment pressures of 0.1 bar or less, which permits the filling of even very light plastic containers, or even square containers; that is, containers which are quite flimsy and unresistant to high pressures.

Claims

A valve filler group in filler machines for liquid containers, comprising
- a liquid flow pipe (1) for inflow of liquid from a tank to a container (10) positioned coaxially below the liquid flow pipe (1), said liquid flow pipe (1) being provided with an obturator (12) to close the liquid flow towards the container (10);

- a pipe (9, 19) for gas or air inserted at least partially in the liquid flow pipe (1), and coaxially to the liquid flow pipe (1);
characterised in that it comprises a device for activating the obturator (12) of the liquid flow pipe (1) in order to bring about a mechanical closure of said pipe (1), independently of a speed at which the filler machine is operating, and contemporaneously with a hydraulic closure of said liquid flow pipe (1) caused by a reaching of a desired level of liquid in a container (10), where the liquid contacts a lower end of a return pipe (19).
A valve group as in claim 1, characterised in that the device comprises a connection membrane (3) between the gas pipe (9) and the liquid flow pipe (1), said membrane (3) permitting movement of the gas pipe (9) with respect to the liquid flow pipe (1), and being of a sufficient length to guarantee that a pressure present in the two said pipes (1, 9) at a reaching of a predetermined liquid level in the container (10) is such as to force the gas pipe (9) upwards into a position in which the obturator (12) is closed.
A valve group as in claim 1, wherein the device comprises a level sensor (21) for perceiving a presence of liquid and for activating, through an amplifier (23), a solenoid valve (24) which, by increasing or diminishing an air flow section towards an outflow channel (4), causes either an opening or a closing of the liquid flow pipe (1).
A valve group as in claim 2, characterised in that it comprises a cam (17) for bringing a stem (7) of the valve group to assume a plurality of different angular positions, each said position corresponding to a diameter of a calibrated orifice (6) releasing air or gas.
A valve group as in claim 1, wherein the device comprises a chamber (16) situated above the gas pipe (9) and kept separate from the zone comprised between the pipes (1 and 9), a chamber internal pressure level depending either on an opening of a valve (5) placing said chamber (16) in communication with an outside environment, or on a return of air from the container (10) during a filling phase; a variation of pressure in the chamber (16) causing a descent of the gas pipe (9) with a flow of liquid, or a rising of the gas pipe (9) into a closed position.
A valve group as in claim 5, wherein the chamber (16) is provided with a calibrated orifice (6) for expelling the air into the outside environment, such that return air coming from the container (10) does not come into contact with a product.
A valve group as in claim 1, wherein the device is constituted by a floating piston provided with a gasket, said piston being solid with the gas pipe (9) and moving between an upper position in which it is open for a flow of liquid and a lower position in which it is closed to such flow.