Bag filling valve for viscous fluids

A housing (10) has a cavity (18) to which fluid product can be fed, and which opens into a terminal neck (20) adapted to be inserted over a bag straw. A hollow bolt (28), having a bore at its tip, is slidable in the housing between a neck-shutting position and a position in which its tip is remote from the neck mouth. A needle (34) is axially slidable in the bolt and protrudes with an enlarged head (35) within the terminal neck through the terminal bore. The needle is biased by a spring (38) to a position where the enlarged head abuts against the tip of the bolt. A drive cylinder (44) is provided for moving the bolt and the needle away from the terminal neck, for connecting the bolt to the internal cavity of the housing, for subsequently bringing the bolt near the neck in order to break the connection and to push the needle so that its enlarged head moves away from the bolt. The portion of the needle adjacent to its enlarged head is smaller than the bore, so that gas fed to the hollow bolt is allowed to flow through.

BACKGROUND OF THE INVENTION 
This invention is concerned with a filling or metering valve for use in 
filling flexible bags with viscous fluids, such as with cream, yoghurt, 
honey, fruit juices, medicines and other viscous products. 
The process of filling flexible bags with viscous substances, particularly 
foods, has been difficult to automate. Firstly, the very viscosity of the 
material requires injection under pressure. Secondly, it is necessary that 
a vacuum is preliminarily made in the bag, in order to avoid that air 
pockets are trapped inside it. Lastly, considerations of convenience 
require that the bag is only filled up to a certain level, a sterile, 
non-oxidizing atmosphere (typically nitrogen) being formed above it. 
These steps should be completed while preventing the product both from 
dripping outside the bag and soiling it and from leaking into undesired 
areas of the equipment, so as to avoid, on the one hand, that the product 
causes clogging of the duct, which would adversely affect the operation of 
the apparatus, and also, on the other hand, that hotbeds of bacterial 
proliferation may develop in places that are difficult to access and 
therefore difficult to sanitize. Known filling bags achieve one or the 
other of the aims above, but they generally fail to satisfy all 
requirements. 
It is the main object of the invention to provide a filling valve for 
flexible bags, by which a predetermined dose of a fluid substance, even of 
a high viscosity, can be injected into a bag, with preliminary suction and 
subsequent introduction of an inert gas, and while preventing the viscous 
product both from dripping onto the bag and from coming into contact with 
pairs of the valve not directly belonging to its path. 
SUMMARY OF THE INVENTION 
The above object, as well as other objects and advantages such as will 
appear from the disclosure, are achieved by the invention with a bag 
filling valve having the features recited in claim 1.

DESCRIPTION OF PREFERRED EMBODIMENTS 
With reference to FIG. 1, a filling valve according to the invention 
comprises a metallic tubular housing 10, which is assembled with an 
attachment 12 by means of a locking ring 14. Housing 10 is threaded at the 
bottom in a mounting bracket 16 of a filling equipment or machine, not 
shown, known in the art, suitable for filling flexible bags. 
Housing 10 has an inside cavity 18, downwardly tapering down to a neck 20, 
adapted to rest onto a filling straw 19 of a flexible bag, known per se. A 
transverse passage 21 opens into neck 20, and leads to a connector 22 for 
connection with a vacuum pump not shown. 
Cavity 18 is in communication with a product-feeding side duct 23, which is 
fed by a pump not shown. Cavity 18 extends upward into a cylindrical 
passage where a sleeve 24 is received. Within sleeve 24, which is provided 
with gaskets 26, a hollow bolt 28 is slidably received, which is provided, 
at its bottom end, with a sealing ring 30 for shutting off neck 20, and 
with a step 32 for upward stop abutment. 
A needle 34 is slidably received within hollow bolt 28. Needle 34 is 
partially jacketed in a sheath 36, which is itself sealingly slidable 
within hollow bolt 28 against the reaction of a helical compression spring 
38, and is provided, at its top, with a nut 40 adapted to slidably embrace 
the upper end of hollow bolt 28. The diameter of needle 34 is slightly 
less than the inside diameter of sheath 36, so that a gap is formed which 
is in communication with a connector 42 for connection with a source of 
nitrogen, not shown. 
Needle 34 projects downwardly through a bore in the tip of hollow bolt 28, 
and is provided with an enlarged head 35. The portion of needle 34 near 
head 35 is faceted, in order to allow gas to flow along the bore. 
A pneumatic cylinder 44 is vertically mounted on the top of attachment 12 
of housing 10. An operating rod 46 of pneumatic cylinder 44 integrally 
carries a mushroom-shaped hammer 48 at its end. Hammer 48 also elastically 
carries, by the intermediate of a helical compression spring 50, a bracket 
52 hanging from a groove 54 in sheath 36. 
The operation of the above-described filling valve will now be explained 
with reference to both FIGS. 1 and 2. After abutting the straw of the bag 
due to be filled against the flared mouth of neck 20, and while 
maintaining bolt 28 lowered against its funnel-shaped seat in order to 
shut off neck 20, suction is applied to connector 22 in order to create a 
vacuum in the flexible bag. At the end of this step, the straw of the bag 
is pushed home into neck 20, by means not shown, thus masking the 
transverse passage 21. 
Pneumatic cylinder 44 is then driven to raise rod 46 and consequently, 
through the intermediate of bracket 52, both sheath 36 and needle 34, 
until the enlarged head 35 of needle 34 abuts against the tip of bolt 28 
and drags it upwards, thus pushing the bolt away from its seat and 
allowing fluid product to be injected from cavity 18 to neck 20 and from 
there into the straw. 
After the desired dose of fluid product has been introduced, rod 46 is 
lowered, so that hammer 48 pushes needle 34 downwards, and immediately 
afterwards, after compressing spring 38 until abutment of the head of 
sheath 36 against the top of bolt 28, also pushes the latter until it 
abuts against its funnel-shaped seat, in order to intercept all 
communication between cavity 18 and neck 20, while head 35 of needle 34 
again moves away form the tip of bolt 28. Nitrogen is now blown in through 
connector 42. The nitrogen flows along the gap between needle 34 and 
sheath 36 and along the facets 37 of the needle and eventually through 
neck 20 and into the bag, thus shoving back into the bag any traces of 
product that might possibly stick to the free walls of neck 20, to the tip 
of bolt 28 or to the enlarged head 35 of needle 34. 
It can be seen from the above disclosure that the fluid product is strictly 
confined to cavity 18 and neck 20 (and the bag itself) at all times during 
the operating cycle. When suction is applied to passage 21, bolt 28 shuts 
off cavity 18 from the neck, and there is no opportunity that traces of 
product are sucked together with air. Subsequently, before bolt 28 is 
raised to allow the fluid product to flow from cavity 18 into neck 20, 
head 35 of needle 34 plugs the forward bore on bolt 20, while the bag 
straw has already entered completely into neck 20, thus plugging passage 
21. Finally, when bolt 28 is again lowered and head 35 moves away from it, 
the nitrogen pressure prevents any upward backflow within the bolt. 
FIG. 3 shows the terminal portion of a modification of the filling valve. 
The modification of FIG. 3 is similar to FIG. 1 in all respects not shown, 
and the same reference numbers are used for corresponding parts. 
In the modification, bolt 28 is identical to the bolt of FIG. 1, but its 
terminal portion protruding into cavity 18 of housing 10 is guided in a 
tubular projection 100, having a liner 102, and bored along its periphery 
with a number of apertures 104 to allow flow from cavity 18 to terminal 
neck 20. The valve and its operation are otherwise identical to what has 
been disclosed above. 
Although bolt 28 of FIG. 1 overhangs into cavity 18, in the modificationn 
of FIG. 3 the bolt is guided over all its length and in all positions, and 
is therefore stabler and less subjected to vibration and jamming, such as 
might arise in certain operating conditions.