Device and process for filling containers with a liquid

The invention relates to a device and a process for filling containers closed off at one end, in particular folded carton packings, with a liquid, comprising at least one transport device for moving the container (1), a storage container (5) for holding the liquid, and at least one filling head (2) connected to the storage container (5) and able to be closed off by a filling valve; the said filling head (2) being vertically movable in relation to the container (1) and being able to be lowered into this container (1). Reliable control of the relative movement between container (1) and filling head (2) has been achieved by a simple design, and in this way foaming has been safely eliminated in that a flow meter (8) is arranged between the storage container (5) and the filling valve and in that a control device (9) for converting the impulses of the flow meter (8) into vertical movements of the filling head (2) and/or the container (1) is provided and in that the relative movement between the folded carton packing and the filling head (2) is regulated on the basis of the volume of filling liquid flowing into the container (1); this volume being determined by a flow meter (8).

BACKGROUND OF THE INVENTION 
The invention relates to a device and a process for filling containers with 
a liquid, in particular folded carton packings closed off at one end, 
comprising at least one transport device for moving the container, a 
storage container for holding the liquid and at least one filling head 
connected to the storage container and able to be closed off by a filling 
valve; the said filling head being vertically movable in relation to the 
container and being able to be lowered into this container. 
Many designs of fast filling machines for filling milk, juice or similarly 
foaming products are known. In order to avoid a defoaming aggregate in 
these machines which even without it are quire complex from a design point 
of view, it is well known for the filling head to be movable in relation 
of the container in order--at the beginning of, and during, the filling 
process--to have as small a distance as possible between the filling head 
and the bottom of the container or the liquid level so as to avoid 
foaming. 
The relative movement between container and filling head either takes place 
by raising and lowering the container or else by lowering and raising the 
filling head. In addition, a combination of both variants is possible, 
even though this makes little sense from a design point of view. 
From CH-A-681 291 a device for filling liquids is known in which the 
filling head is always to be submerged evenly in the liquid. Control of 
this filling device is quite cumbersome because height measuring takes 
place by weight measuring cells. To this effect, the signals from the 
weight measuring cells have to be processed into weight information by an 
evaluation circuit. The weight information has to be processed in a 
computer for dose rate control to select the position of the filling valve 
in relation to the position of the container to be filled. 
In order to minimise foaming, the task is to synchronise the mechanical 
movement of the container or the filling head with the filling level, 
because for reasons of hygiene the filling head should not be immersed in 
the liquid already held in the container. This task has already been 
solved in prior art by synchronising the lifting movement with the 
movement of a dose rate piston. In the case of older filling machines, 
synchronisation is by means of cam control; in the case of more modern 
machine designs, the movements of the container or of the filling head 
respectively, are carried out by electric servo motors, and movement 
synchronisation is realised by program control. Such a synchronisation of 
two movements is technically demanding and in addition, the use of a dose 
rate piston is expensive and susceptible to wear and malfunction. 
SUMMARY OF THE INVENTION 
From this starting point it is the object of the present invention to 
design and further develop the device for filling containers with a liquid 
or the respective process for this, as mentioned and described in more 
detail above, to the point where reliable control of the relative movement 
between container and filling head can be achieved by a simple design, and 
in this way significantly reduce foaming of the fill product in order to 
avoid subsequent defoaming. 
In a device according to the precharacterizing part of claim 1 this object 
is met in that a flow meter is arranged between the storage container and 
the filling valve and in that a control device for converting the impulses 
of the flow meter into vertical movements of the filling head and/or the 
container is provided. 
In regard to the process according to the invention, the object is met in 
that the relative movement between the container and the filling head is 
regulated on the basis of the volume of liquid flowing into the container; 
this volume being determined by a flow meter. 
The device or the process according to the invention does not need the 
movement of a dose rate piston, because the dose rate flow for the 
container to be filled is measured by a flow meter and processed to a dose 
rate volume in a control device. 
In a further embodiment of the invention, the flow meter is a magnetically 
inductive sensor located in the line carrying liquid between the storage 
container and the filling valve. In this way, the exact volume of 
through-flow can be achieved reliably without any mechanical contact with 
the fill liquid. 
According to a further development of the invention, the filling head is 
fixed in place, and below the filling head, a lifting device for 
raising/lowering the container is provided. As already described, it is 
however also imaginable that the container about to be filled is fixed in 
place below the filling head and that a lifting device for 
lowering/raising the filling head is provided. 
Irrespective of the type of design, it is particularly advantageous if the 
lifting device comprises an axis driven in uniform straight-line motion, 
and a distance measuring device. This allows control of the lifting device 
which is simple from a design point of view and yet very reliable. 
It is particularly advantageous to combine the flow metering--in particular 
the inductive flow metering--with the movement of the lifting device, 
because the movement is realised by an electric servo axis which in turn 
derives its control function from the impulses, proportional to the flow 
rate, of the flow meter. In this way there is a direct--and from a design 
point of view simple realisable--dependence between the movement of the 
lifting device in relation to the container or the filling head and the 
actual filling volume, so that expensive synchronisation of two movements 
can be avoided.

DETAILED DESCRIPTION OF THE INVENTION 
A container 1 which is closed off at one end is arranged on a lifting 
device 3 below a filling head. In this arrangement, the filling head 2 is 
supplied by a filling pipe 4 from a storage container 5 which is fed by a 
supply line 6 only hinted at. Measuring out the filling volume, which 
depends on the size of the containers, is via a filling valve 7 above the 
filling head 2. 
According to the invention, a flow meter 8 is located between the storage 
container 5 and the filling valve 7, and a control device 9 serves to 
convert the impulses of the flow meter 8 into relative vertical movements 
between container 1 and filling head 2. 
In the embodiment shown which so far is the preferred embodiment, the 
filling head 2 is arranged in a fixed position, and the lifting device 3 
serves to raise/lower the container 1. In this way it is possible to 
reliably maintain a constant distance h between the filling head and the 
liquid level. 
It is however also possible, as seen in FIG. 2, for the container to be 
arranged in a fixed position below the filling head and for the vertical 
movement to be carried out by the filling head by the action of the 
lifting device 16. 
In a further embodiment of the invention, the lifting device 3 comprises an 
axis 10 driven in uniform straight-line motion, and a distance measuring 
device 11. In addition, it is particularly advantageous if the flow meter 
8 is designed as a magnetically inductive sensor. 
In the embodiment illustrated, the control device 9 comprises a 
synchronisation controller 12, a position controller 13 and a speed 
controller 14. In this arrangement, selection of the synchronisation 
controller 12 and the position controller 13 is by way of a switch 15 
depending on the impulses of the distance measuring device 11. 
Direct dependence between the volume of liquid already filled into the 
container 1 and the position of the lifting device 3 can be mathematically 
expressed in the formula .DELTA.V.times.c=.DELTA.s, where .DELTA.V 
represents the volume of the product measured out into the container and 
.DELTA.s represents the travelling distance of the lifting device 3.