EP4671541A1

EP4671541A1 - COMPRESSOR DEVICE FOR A PRESSURE SYSTEM OF A PACKAGING MACHINE FOR THE PRODUCTION OF SEALED PACKAGING WITH A FLOWABLE FOOD PRODUCT

Info

Publication number: EP4671541A1
Application number: EP25182913.1A
Authority: EP
Inventors: Paolo SANIBONDI; Claudio Ferrari; Filippo Ferrarini; Renzo Bellei; Angelo MARSELLA; Danilo Veroni
Original assignee: Tetra Laval Holdings and Finance SA
Current assignee: Tetra Laval Holdings and Finance SA
Priority date: 2024-06-28
Filing date: 2025-06-16
Publication date: 2025-12-31
Also published as: WO2026002691A1

Abstract

There is described a compressor device (13) for a pressurization system (12) of a packaging machine (1) configured to produce packages (2) starting from a tube (3) of packaging material, the compressor device (13) comprises an impeller (16) and a casing body (17) internally defining an impeller vane (18) and a receiving seat (19) for the impeller (16), the impeller (16) and the receiving seat (19) are separated by a gap (24) which fluidically connects the impeller vane (18) with an external environment (50) outside of the compressor device (13) for allowing the passage of air in overpressure from the impeller vane (18) through the gap (24) and towards the external environment (50); the compressor device (13) comprises a seal member (25) arranged at said gap (24), the seal member (25) is configured to be controlled in: an opening position, in which it delimits a passage together with said impeller (16) or said receiving seat (19) for allowing the passage of air in overpressure through the gap (24); and a closing position, in which it fluid-tightly seals the gap (24).

Description

TECHNICAL FIELD

The present invention relates to a compressor device for a pressurization system of a packaging machine configured to produce sealed packages containing a pourable food product. The present invention also relates to a pressurization system and a packaging machine. The present invention also relates to a method for producing sealed packages.

BACKGROUND ART

As it is generally known, many pourable food products, such as fruit juice, UHT (ultra-high temperature-treated) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material.
A typical example is the parallelepiped-shaped package for pourable food products known as Tetra Brik Aseptic (registered trademark), which is made by folding and sealing a laminated web of packaging material. The packaging material has a multilayer structure comprising a base layer, e.g. made of paper, covered on both sides with layers of heat-seal plastic material, e.g. polyethylene. In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of oxygen-barrier material, e.g. an aluminum foil, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material forming the inner face of the package eventually contacting the food product.
Packages of this sort are normally produced on fully automatic packaging machines, which form and fill the packages starting from a multilayer web of packaging material.
In particular, in such packaging machines a continuous tube is formed from the web of packaging material which is initially wound in a reel and fed through a plurality of unwinding rollers.
The web of packaging material is typically fed through a sterilization apparatus for sterilizing the web and then into an isolation chamber which encloses an environment controlled in sterile and/or aseptic conditions, i.e. containing sterile and/or aseptic air.
While advanced by the aforementioned unwinding rollers, the web is folded to form the tube by means of a known web folding unit and then sealed longitudinally. Hence, the tube is provided with a longitudinal seal before exiting the isolation chamber.
In order to perform the package forming operations, the tube is continuously fed along a first direction, normally a straight vertical direction, is filled with the sterilized food product from above and is formed, sealed and subsequently cut along equally spaced transversal cross-sections extending along a second direction, normally a direction orthogonal to the first direction.
A sequence of pillow packs is thereby obtained, which pillow packs are then fed to a folding device of the packaging machine for the final folding thereof.
Fully formed and folded packages are thereby obtained.
A packaging machine of the above type further comprises a filling system configured to fill the tube with the pourable product, while the tube is continuously formed, sealed and advanced along said first direction.
In detail, the filling system comprises a filling pipe which is inserted in, and surrounded by, the tube in formation, and which delivers the pourable product into the tube, so that a column of pourable product is defined and maintained within the tube.
In order to correctly form the pillow packs, and therefore in order to obtain finished fully-folded packages which reproduce a nominal desired conformation, it is required that the hydrostatic pressure provided within the tube is sufficiently high, since otherwise irregularly shaped packages may be obtained.
According to a known configuration, such hydrostatic pressure is provided by the column of pourable product within the tube. However, depending on the package format and on the desired production speed, such column of pourable product can reach a relatively large extension in order to guarantee the needed hydrostatic pressure. Furthermore, during a starting transient of the packaging machine, the column of pourable product may have not yet reached the nominal extension required for defining the nominal hydrostatic pressure.
This may result in a relatively large number of discarded packages.
In order to overcome the aforementioned drawbacks, EP-A-3456638 discloses a packaging machine of the above type and comprising a pressurization system configured to feed compressed (i.e. pressurized) air towards the column of pourable product.
The pressurization system includes:

a compressor device configured to suction sterile and/or aseptic air from the isolation chamber and to compress this suctioned air;
a gas feeding duct fluidically connected to the delivery of the compressor device and designed to feed the compressed air towards the column of pourable product; and
a delimiting element or flange or plate fixed to the gas feeding duct, arranged within the tube and dividing the tube in a first space being in fluidic connection with the sterile environment and a second space being arranged downstream of the first space.

The delimiting plate has a central passage through which the filling pipe extends.
In particular, the pressurization system is operable in:

a operational configuration in which the impeller 16 rotates and the seal member 25 is controlled in the opening position thereby allowing the passage of air in overpressure through the gap 24, and
a cleaning configuration in which the impeller 16 is stopped from rotating and the seal member 25 is controlled in the closing position, thereby preventing a cleaning medium to leak through the gap 24.
The feeding duct is configured to supply the compressed air into the second space (with the pressurization system being controlled in the operational configuration), thereby controlling the pressure therein to be greater than the pressure within the first space and the sterile environment delimited within the isolation chamber.

An overpressure is thereby defined within the second space with respect to the first space and the isolation chamber. In this way, the aforementioned pressure can be controlled, and in particular increased, so that the extension of the column of pourable product can be reduced while obtaining the same value of hydrostatic pressure.
A narrow passage is defined between the delimiting plate and the inner wall of the tube, so as to allow a smooth advancement of the tube without wearing this latter.
Hence, some of the compressed air fed into the second space returns, due to the aforementioned overpressure within the second space, into the first space, and from this latter back into the isolation chamber.
Therefore, the pressure within the isolation chamber is maintained constant throughout the packaging operation (in particular, under nominal operating conditions).
The compressor device typically includes a casing body, an impeller and a motor for driving the impeller.
The casing body defines a seat for the impeller.
A calibrated narrow gap is defined between the impeller and the seat, i.e. between the impeller and the casing body. Such gap fluidically connects an impeller vane housing the impeller blades and the external environment. In this way, part of the air suctioned by the compressor leaks through this narrow gap and towards the external environment. In fact, the compressor device defines a high pressure zone at the impeller, with a pressure higher than the pressure of the external environment.
Hence, with the pressurization system being controlled in the operational configuration, an overpressure is defined between the high pressure zone and the external environment, which determines a flow of air through the gap and towards the external environment, thereby avoiding contamination from the external environment towards the impeller vane.
The need is known for cleaning the aforementioned components, and in particular the filling system and the pressurization system.
In order to perform the cleaning operation, the packaging machine is stopped, the compressor device is stopped and the filling system, the pressurization system and/or the isolation chamber are fed with a cleaning medium, such as water or chemically treated/enhanced water.
Preferably, the packaging machine 1 and/or pressurization device 12 comprises a cleaning medium supplier (not shown), configured to supply the cleaning medium to the pressurization system and/or the isolation chamber and/or the impeller vane 18. The packaging machine 1 is configured to set the pressurization system 12 in the cleaning configuration when the cleaning medium supplier supplies the cleaning medium to the impeller vane 18. In such a way, leakage of the cleaning medium through the gap is prevented.
Although the packaging machines, pressurization systems and compressor devices of the above-mentioned type work satisfyingly well, the Applicant observed that they are still open to further improvements, in particular as per the cleanability, hygiene and durability thereof.

DISCLOSURE OF INVENTION

It is therefore an object of the present invention to provide a compressor device for a pressurization system of a packaging machine which is designed to meet the above-mentioned need in a straightforward and low-cost manner. Also, it is an object of the present invention to provide a pressurization system, a packaging machine and a method for producing sealed packages that meet the above-mentioned need.
This object is achieved by a compressor device as claimed in the appended independent claim 1, a pressurization system as claimed in claim 13, a packaging machine as claimed in claim 15 and a method as claimed in claim 16. Preferred embodiments of the present invention are laid down in the appended dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a schematic perspective view, with parts removed for clarity, of a packaging machine including a pressurizing system having a compressor device according to the present invention;
Figure 2 is a larger-scale, partially sectioned side view, with parts removed for clarity, of part of the packaging machine of Figure 1 showing the pressurization system;
Figure 3 is a sectioned view, with parts removed for clarity, of the compressor device according to a first preferred embodiment of the present invention;
Figures 4a and 4b are larger-scale sectioned views, with parts removed for clarity, of a detail of the section of the compressor device of Figure 3, during two distinct operative conditions;
Figure 5 is a sectioned view, with parts removed for clarity, of the compressor device according to a second preferred embodiment of the present invention; and
Figures 6a and 6b are larger-scale sectioned views, with parts removed for clarity, of a detail of the section of the compressor device of Figure 5, during two distinct operative conditions.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figure 1, number 1 indicates as a whole a non-limiting example of a packaging machine for producing a plurality of packages 2 containing a pourable product, preferably a pourable food product such as pasteurized or UHT milk, water, fruit juice, wine, peas, beans, etc.
In detail, packaging machine 1 is configured to form, seal and fold packages 2 starting from a web 4 of packaging material, which is initially wound in a reel 40, and then folded into a tube 3 of packaging material, as explained below.
Preferably, the packaging material has a multilayer structure (not shown), and comprises a layer of fibrous material, e.g. paper, covered on both sides with respective layers of heat-seal plastic material, e.g. polyethylene.
In the case of aseptic packages 2 for long-storage products, such as UHT milk, the packaging material also comprises a layer of gas-and-light barrier material, e.g. aluminum foil or ethylene vinyl alcohol (EVOH) film, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material, the latter forming the inner face of package 2 eventually contacting the pourable product.
As said, the packaging material is initially provided in the form of a web 4.
Packaging machine 1 comprises conveying means (only partially shown) configured to advance web 4 along an advancement path.
As visible in Figure 1, packaging machine 1 further comprises a web folding device 5 for progressively folding the advancing web 4 into a tube 3, in a manner known and not described in detail.
Packaging machine 1 further comprises a sealing device 6 for longitudinally sealing tube 3.
Packaging machine 1 also comprises a forming and sealing unit 7 (known per se and only partially visible in Figure 2) for repeatedly forming and transversally sealing tube 3 at successive cross-sections thereof, thereby obtaining a plurality of packs 2a from which packages 2 are subsequently obtained.
In detail, forming and sealing unit 7 is configured to sequentially impart a predetermined external shape, corresponding to a precursor of the shape of package 2, to successive longitudinal portions of tube 3, and to transversally seal tube 3 at equally spaced cross-sections.
Packaging machine 1 further comprises a folding unit (not shown) designed to fold packs 2a for obtaining packages 2.
As visible in Figure 1, packaging machine 1 comprises a filling system 8 configured for supplying pourable product into tube 3 (during its formation).
Furthermore, packaging machine 1 comprises an isolation chamber 10 enclosing a substantially sterile or aseptic environment. In detail, isolation chamber 10 is designed to contain sterile and/or aseptic air. In particular, isolation chamber 10 houses web folding device 5, the sealing device 6 and, preferably, at least part of the filling system 8.
Preferably, packaging machine 1 has an axis X along which tube 3 is fed, in use.
Axis X is parallel to a straight direction, which preferably is a straight vertical direction.
Hence, in use, tube 3 is fed along axis X, downwards, and while being filled from above by filling system 8 is formed and sealed by the forming and sealing unit, according to a manner known and not described in detail.
More specifically, tube 3 is drawn (downwards) along axis X by forming and sealing unit 7 in a known manner.
As visible in particular in Figure 2, filling system 8 comprises a product filling pipe 11 designed to be arranged (at least partially) within tube 3, i.e. arranged in use within tube 3 so that tube 3 surrounds filling pipe 11, and configured to supply pourable product within tube 3.
In particular, filling pipe 11 is in fluid connection or is controllable to be in fluid connection with a pourable product storage tank (not shown and known as such), which is adapted to store/provide for the pourable product, in particular the sterilized and/or sterile-processed pourable food product, to be packaged.
Preferably, at least a portion of filling pipe 11 is arranged coaxial with axis X, i.e. with tube 3.
Packaging machine 1 further comprises a pressurization system 12 configured for pressurizing tube 3, as explained hereinafter.
Pressurization system 12 comprises a compressor device 13 configured to suction air, in particular by means of an inlet duct 13a thereof, from isolation chamber 10, to pressurize (i.e. compress) the suctioned air, and to deliver the pressurized (i.e. compressed) air, in particular by means of an outlet duct 13b thereof, towards tube 3.
Pressurization system 12 further comprises a gas feeding duct 14 fluidically connected to outlet duct 13b and designed to feed the pressurized air into tube 3.
Pressurization system 12 further comprises a delimiting element 15, for example a delimiting flange or plate, connected to gas feeding duct 14, configured to be arranged, in use, within tube 3 for dividing tube 3 in a first inner compartment or space 3a and a second inner compartment or space 3b arranged downstream of first space 3a, relatively to the advancement direction of tube 3 along axis X.
In particular, as visible in Figures 1 and 2, first space 3a is in fluidic connection with isolation chamber 10, more in particular first space 3a is open towards isolation chamber 10.
Second space 3b is fluidically connected with gas feeding duct 14 and is configured to receive the pressurized air therefrom.
Basically, second space 3b is delimited between delimiting element 15 and forming and sealing unit 7.
More precisely, second space 3b is delimited between delimiting element 15 and the first subsequent transversal seal of tube 3 defined, in use, by forming and sealing unit 7 (Figure 2).
Filling pipe 11 is configured to supply the pourable product into second space 3b.
Preferably, gas feeding duct 14 extends, at least in part, parallel to axis X. More preferably, gas feeding duct 14 is arranged coaxially to filling pipe 11.
More precisely, gas feeding duct 14 surrounds filling pipe 11, so that an annular flow channel for the compressed gas is delimited between an outer (lateral) surface of filling pipe 11 and an inner (lateral) surface of gas feeding duct 14.
As visible in Figure 2, delimiting element 15 is mounted coaxially with gas feeding duct 14.
Appropriately, delimiting element 15 does not contact tube 3, so that first space 3a is not fluid-tightly separated from second space 3b.
Instead, a relatively small (annular) passage is defined between delimiting element 15 and tube 3. In such a way, it is allowed a fast advancement of tube 3 without contacting delimiting element 15, which would be detrimental to the wear of tube 3 itself.
Hence, second space 3b is fluidically connected to first space 3a.
In other words, delimiting element 15 is configured to be arranged at a non-zero distance from an inner wall of tube 3, thereby allowing a recirculation (schematized in Figure 2) of some of the compressed air from second space 3b towards first space 3a and from first space 3a back into isolation chamber 10.
In this way, the pressure within the isolation chamber 10 is maintained constant and higher than ambient pressure, i.e. than the pressure at an external environment 50 outside of isolation chamber 10 and outside of compressor device 13.
In light of the above, pressurization system 12 allows to control the pressure in second space 3b, i.e. in the inner space of tube 3 where the pourable product is fed in use.
In this way, as it is known, it is possible to reduce the extension of the column of pourable product while maintaining the hydrostatic pressure within the second space 3b of tube 3 at the desired value.
As visible in Figures 3 and 5, compressor device 13 comprises an impeller 16 and a casing body 17.
Casing body 17 internally defines an impeller vane 18 and a receiving seat 19 for impeller 16.
Furthermore, casing body 17 internally defines a volute 20 of compressor device 13.
Impeller vane 18 is arranged in fluidic communication with inlet duct 13a, on one side, and with volute 20, on the other side. In turn, volute 20 is arranged in fluidic communication with outlet duct 13b.
In use, the air suctioned via inlet duct 13a reaches impeller vane 18, is compressed/pressurized by the blades of impeller 16, flows into volute 20 and is then fed through outlet duct 13b to gas feeding duct 14.
Impeller 16 has a longitudinal axis A.
Compressor device 13 further comprises a motor 21 operatively coupled to impeller 16 and configured to drive impeller 16.
In particular, motor 21 is configured for actuating impeller 16 in rotation about axis A, which therefore defines a central rotation axis for the impeller 16 itself.
Impeller 16 includes a shaft 22, which extends along axis A and engages receiving seat 19, and a bladed body 23, which is carried by shaft 22 and develops about axis A. Bladed body 23 is partially arranged in impeller vane 18.
Preferably, shaft 22 and bladed body 23 are made in one single piece.
Motor 21 is coupled with impeller 16 via a driving shaft 22a axially extending from shaft 22, at a side thereof opposite to bladed body 23.
It is specified that driving shaft 22a is arranged outside receiving seat 19. In other words, only shaft 22 is arranged within receiving seat 19.
Bladed body 23 includes a front portion 23a which carries a plurality of blades and is arranged within impeller vane 18.
More precisely, front portion 23a engages impeller vane 18 and faces an internal surface of casing body 17 which delimits impeller vane 18.
Bladed body 23 also includes a discoidal rear portion 23b which extends from shaft 22, supports front portion 23a and faces receiving seat 19.
More precisely, rear portion 23b engages receiving seat 19, thereby being part of the portion of impeller 16 which is arranged within receiving seat 19, together with shaft 22.
In other words, rear portion 23b defines a so-called "back disk" of impeller 16.
As visible in Figures 3, 4a and 4b, impeller 16 and receiving seat 19 are separated by a gap 24 which fluidically connects impeller vane 18 with the aforementioned external environment 50 for allowing the passage of air in overpressure from impeller vane 18 through gap 24 and towards external environment 50.
More specifically, gap 24 is delimited between receiving seat 19, on one side, and shaft 22 and rear portion 23b, on the other side, as shown in Figure 3.
It is stated that the external environment 50 includes the environment which is not to be controlled and maintained in sterile and/or aseptic conditions, i.e. the environment external to isolation chamber 10, and casing body 17. That is, also the area of compressor device 13 at which motor 21 is located is encompassed in the external environment 50.
Gap 24 defines a narrow passage fluidically connecting impeller vane 18 and external environment 50.
The presence of gap 24 ensures that part of the air suctioned by compressor device 13 and compressed within impeller vane 18 leaks through this narrow passage and towards external environment 50 (e.g. towards motor 21).
In fact, compressor device 13 defines a high pressure zone at the impeller vane 18 having a pressure higher than the pressure of external environment 50.
Hence, an overpressure is defined between the high pressure zone and the external environment 50, which determines a positive flow of air through gap 24 and towards external environment 50, thereby preventing a contamination from external environment 50 towards impeller vane 18.
In this way, sterile and/or aseptic conditions of compressor device 13 are ensured throughout the packaging operation.
The need for cleaning various components of packaging machine 1 and of pressurizing system 12 is known.
In particular, various components as gas feeding duct 14, feeding pipe 11, and the internal parts of compressor device 13 such as impeller vane 18, impeller 16, receiving seat 19, volute 20, need to be cleaned.
To this end, a cleaning process is defined whereby packaging machine 1 is stopped and cleaning medium (such as water or chemically treated and/or enhanced water) is fed within the pressurization system 12.
Hence, the cleaning medium is also fed within impeller vane 18, receiving seat 19 and volute 20.
Therefore, due to the presence of gap 24, a significant amount of cleaning medium may leak through gap 24 and towards external environment 50.
According to an important aspect of the present disclosure, compressor device 13 comprises a seal member 25 arranged at gap 24 and configured to be controlled in:

an opening position, in which it delimits a passage together with impeller 16 or receiving seat 19 for allowing the passage of air in overpressure through gap 24 (and towards external environment 50); and
a closing position, in which it fluid-tightly seals gap 24.

In particular, seal member 25 is carried by one of the impeller 16 and casing body 17.
Accordingly, seal member 25 is configured to cooperate in fluid-tight contact with the other of the impeller 16 and casing body 17 when controlled in the closing position.
According to a preferred embodiment of the invention, seal member 25 is carried by casing body 17 at receiving seat 19.
Accordingly, seal member 25 is configured to abut in fluid-tight manner against impeller 16 for closing and sealing gap 24 when controlled in the closing position.
In other words, seal member 25 is fitted on the casing body 17, at receiving seat 19, and is configured to selectively abut against impeller 16 when controlled in the closing position. In this way, no gas or liquid (such as the cleaning medium) can flow and escape through gap 24 and leak towards external environment 50.
Conversely, when controlled in the opening position, seal member 25 is spaced from impeller 16 by a non-zero distance.
Thanks to the presence of seal member 25, selectively controllable in the opening position and closing position, a two-fold operative configuration of compressor device 13 can be obtained in a rather simple manner: during the nominal packaging process, seal member 25 is controlled in the opening position, thereby allowing the passage of air in overpressure through the gap 24; whereas, during the cleaning process, seal member 25 is controlled in the closing position, thereby preventing the cleaning medium to leak through gap 24, thereby enhancing the hygiene conditions and cleanliness of pressurization system 12 and packaging machine 1.
Moreover, the use of seal member 25 as described above is significantly more advantageous than the use of a dynamic seal which is arranged in sliding contact with impeller 16 throughout the packaging process. In fact, seal member 25 according to the disclosure is controlled to be in contact with impeller 16 only when necessary, such as during cleaning operations (during which impeller 16 is stopped, i.e. is not actuated in rotation by motor 21); conversely, dynamic seals that are always in contact with the impeller generate constant friction, which can lead to heat buildup; the described seal member 25 prevents this friction by only engaging when necessary, i.e. when the impeller 16 is not rotating, reducing heat generation and associated wear. This selective sealing contact reduces the wear and tear on both the impeller and, most importantly, the seal member, extending their operational life. Furthermore, when the seal member 25 is in the opening position, it does not impede the rotation of the impeller 16, leading to more efficient operation of the compressor device 13; this results in lower energy consumption and improved overall performance of the packaging machine 1.
Opportunely, compressor device 13 comprises an actuator device configured for controlling seal member 25 between the opening position and the closing position.
Preferably, seal member 25 is made of an elastomeric material, is hollow and internally defines an inflatable chamber 27.
Advantageously, the actuator device includes a pneumatic circuit 28 (only partially shown) configured to selectively:

supply gas (e.g. air) into inflatable chamber 27 for determining an inflation of seal member 25 thereby controlling seal member 25 in the closing position;
suction air from inflatable chamber 27 for determining a deflation of seal member 25 thereby controlling seal member 25 in the opening position.

Alternatively, in order to determine the deflation of seal member 25 the pneumatic circuit 28 may only release the pressure within the inflatable chamber 27, e.g. by opening a valve, without actively suctioning air from inflatable chamber 27. In this case, the "spring-back" effect of the elastomeric material of the seal member 25 is exploited to push the air out from the inflatable chamber 27.
The inflated condition of seal member 25 is shown in Figure 4b, which also corresponds to the closing position of seal member 25.
The deflated condition of the seal member 25 is shown in Figure 4a, which also corresponds to the opening position of seal member 25.
Thanks to the actuator device of the pneumatic type, seal member 25 can be controlled between the opening position and closing position in an easy and simple manner, without involving a large number of components and without the need for a lot of dedicated space within compressor device 13. In fact, pneumatic actuators generally have fewer moving parts and simpler mechanisms compared to other type of actuators; this simplicity results in reduced maintenance requirements and easier servicing, lowering the overall operational costs and downtime. Furthermore, pneumatic actuators do not generate significant heat, making them safe for use in sterile and aseptic environments, which are common in packaging machines handling sensitive products. Moreover, pneumatic actuators can apply a consistent and precisely adjustable sealing force, ensuring that seal member 25 achieves a reliable seal against impeller 16. This consistency is crucial for maintaining the integrity of the seal over repeated cycles of operation.
Figure 3 illustrates a first preferred embodiment of the present disclosure, according to which seal member 25 is configured to abut against shaft 22 when controlled in said closing position.
In particular, according to this first preferred embodiment, receiving seat 19 includes a recess 26 facing shaft 22 along a radial direction, relative to axis A (i.e. radial direction is perpendicular to axis A).
Accordingly, seal member 25 is arranged within recess 26 when controlled in the opening position and is configured to abut against shaft 22 when controlled in the closing position, so that the abutment direction is parallel to the radial direction.
These two conditions are respectively shown in Figures 4a (opening position) and Figure 4b (closing position).
The Applicant has found that this peculiar configuration (i.e. the radial abutment direction of seal member 25) is particularly advantageous for improving the cleanability of the rear part of impeller 16, i.e. the part of impeller 16 which faces receiving seat 19.
In fact, during the cleaning process, when seal member 25 is controlled in the closing position, seal member 25 abuts against shaft 22. This results in the entirety of the rear portion 23b (i.e. the "back disk" of impeller 16) being reachable by the cleaning medium via gap 24. Also, part of shaft 22 is reachable by the cleaning medium.
Seal member 25 has an annular shape and, according to the aforementioned first embodiment, annularly extends about axis A and shaft 22.
Expediently, also recess 26 has an annular shape and annularly extends about axis A and shaft 22.
Opportunely, the surface of seal member 25 that abuts against impeller 16 is oriented radially, with respect to axis A.
Advantageously, seal member 25 has a substantially W-shaped cross section (Figures 3, 4a, 4b).
In detail, seal member 25 has two free ends and two concave middle portions which determine the W-shape cross section.
In greater detail, the two free ends of seal member 25 are fixed to recess 26, whereas the two concave middle portions are configured to protrude (i.e. exit) from recess 26 when seal member 25 is controlled in the closing position, up to reach shaft 22 in abutment.
The Applicant has observed that such conformation of seal member 25 improves the elasticity thereof, ensuring that seal member 25 effectively and promptly returns in its opening position. In fact, the elastic properties deriving from a seal member 25 with a W-shaped cross section help it return to its original shape (i.e. within recess 26) after being compressed against impeller 16; this resilience ensures that the seal can undergo repeated cycles of compression and decompression without permanent deformation, maintaining its sealing integrity over time.
Furthermore, when compressed, the W-shape allows for more uniform distribution of the compressive forces; this uniformity reduces the risk of localized wear and tear, enhancing the longevity of the seal member 25. Moreover, the W-shape provides multiple contact points and sealing surfaces against impeller 16. Even if one part of the seal becomes compromised, the other parts can still maintain an effective seal, increasing the overall reliability of the sealing mechanism.
Alternatively, seal member 25 may have a substantially D-shaped cross section.
This configuration is easier and cheaper to manufacture and install and also provides for a stronger sealing abutment against impeller 16.
Figure 5 shows a second preferred embodiment of compressor device 13 according to the present disclosure.
In particular, compressor device 13 according to this second preferred embodiment is substantially similar to the one according to the first embodiment, with the difference that sealing member 25 is configured to abut against bladed body 23 when controlled in the closing position, instead of abutting against shaft 22.
In particular, casing body 17 includes a recess 26 facing rear portion 23b of bladed body 23 along the axial direction, relative to axis A.
According to the second preferred embodiment, seal member 25 is arranged within recess 26 when controlled in the opening position and is configured to abut against rear portion 23b when controlled in the closing position, so that the abutment direction is parallel to the axial direction.
These two conditions are respectively shown in Figures 6a (opening position) and Figure 6b (closing position).
The Applicant has found that this peculiar configuration (i.e. the axial abutment direction of seal member 25) is particularly advantageous for maintaining the position of impeller 16 during the cleaning process.
More specifically, during the cleaning process, impeller 16 must be stopped; however, the supply of the cleaning medium may cause the impeller 16 to rotate, due to the interaction between the cleaning medium and the blades.
The Applicant has observed that the abutting action of seal member 25 against the rear portion 23b of the bladed body 23, i.e. against the "back disk" of impeller 16, determines an efficient braking action on the impeller 16 itself. In fact, according to this configuration seal member 25 applies a higher braking torque compared to the aforementioned case in which seal member 25 abuts against shaft 22. Such higher braking torque may be preferable in some operative conditions. Thus, there is no need for an auxiliary braking system and/or a smaller pneumatic pressure can be applied for maintaining impeller 16 in position (i.e. stopped) during the cleaning process.
Furthermore, the Applicant has observed that a seal member 25 axially abutting against rear portion 23b is easier to manufacture, given also the fact that the size of compressor device 13, and therefore of shaft 22, is rather small. In fact, the small size of seal member 25 may affect the elasticity of the material thereof.
Also in this case, seal member 25 has an annular shape and, according to the aforementioned second embodiment, annularly extends about axis A.
However, the surface of seal member 25 that abuts against impeller 16 is oriented axially with respect to axis A, instead of radially.
Preferably, seal member 25 according to this second embodiment has a substantially D-shaped cross section.
The Applicant has observed that this configuration works better with the axial abutment direction of seal member 25, since it enhances the braking action of the seal member 25. In fact, a D-shaped seal member 25 provides for a larger abutment surface.
Alternatively, seal member 25 may have a W-shaped cross section as mentioned above, thereby obtaining the elastic return properties described above.
Preferably, compressor device 13 further comprises a pressure sensor 29 configured to detect a pressure within inflatable chamber 27.
Accordingly, compressor device 13 may include a control unit logically connected to pressure sensor 29.
Thanks to pressure sensor 29, it is possible to verify if the nominal pressure requested for maintaining the sealing action at gap 24 during cleaning is reached within seal member 25.
In fact, pressure sensor 29 provides real-time data on the pressure within inflatable chamber 27, thereby allowing for continuous monitoring and ensuring that seal member 25 is functioning correctly at all times. Furthermore, the system can dynamically adjust the inflation and deflation of seal member 25; this responsiveness ensures that the seal is always at the optimal pressure, providing effective sealing without overinflation or underinflation. In fact, an overpressure could damage the seal member 25 or the impeller 16, whereas and underpressure could result in inadequate sealing. Accordingly, the control unit provides alerts when the pressure deviates from the optimal range; this automated alert system helps in proactive maintenance, reducing the risk of unexpected failures and downtime.
According to an alternative embodiment not shown, the actuator device may include, instead of pneumatic circuit 28, mechanical or electromechanical or magnetic or electromagnetic means for controlling seal member 25 between the opening position and the closing position.
An actuator device of such type may provide a more reliable, secure and enhanced sealing action when controlling seal member 25 in its closing position, despite requiring a more complicated architecture.
The present description also provides a method for producing sealed packages 2 containing a pourable product starting from a web 4 of packaging material.
The method comprises a step of advancing the web 4 of packaging material.
The method comprises a step of folding the web 4 into a tube 3.
The method comprises a step of longitudinally sealing the tube 3.
The method comprises a step of supplying the pourable product into the tube 3; wherein a delimiting element 15 (as disclosed above) is arranged within the tube 3 for dividing the tube 3 in a first space 3a being in fluidic connection with the isolation chamber 10 containing sterile and/or aseptic air and a second space 3b being arranged downstream of the first space 3a along a tube advancement path.
The method comprises a steps of suctioning air from the isolation chamber 10, pressurizing the suctioned air, and delivering the pressurized air to the gas feeding duct 14, by means of the compressor device 13.
It is noted that seal member (25) is controlled in the opening position, during the steps of suctioning air, pressurizing the suctioned air and delivering the pressurized air.
The method comprises the step of feeding pressurized air from the gas feeding duct 14 into the second space 3B.
The method comprises the step of forming and transversally sealing the tube 3 at successive cross-sections thereof, thereby obtaining a plurality of packs 2a from which the packages 2 are subsequently obtained.
The method further comprises the steps of:

moving the seal member 25 into a closing position, in which it fluid-tightly seals the gap 24,
- with the seal member 25 being in the closing position, feeding a cleaning medium within the impeller vane 18 and/or the pressurization device 12 and/or the isolation chamber 10.The advantages of compressor device 13, and therefore of the pressurizing system 12, packaging machine 1 comprising the same and the method, according to the present invention will be clear from the foregoing description.

In particular, seal member 25 selectively controllable in the opening position and closing position allows for optimally performing both the packaging process and the cleaning process, in a rather simple and cost-effective manner.
In fact, during the packaging process, the seal member 25 is controlled in the opening position, thereby allowing the passage of air in overpressure through the gap 24 thus preventing contaminants to enter in the sterile/aseptic zone of the compressor device 13 and allowing impeller 16 to rotate with a significatively reduced friction. Conversely, during the cleaning process, seal member 25 is controlled in the closing position, thereby preventing the cleaning medium to leak through gap 24, thereby enhancing the hygiene conditions and cleanliness of pressurization system 12 and packaging machine 1.
This selective double configuration of seal member 25 avoids the use of a dynamic seal arranged in sliding contact with impeller 16 throughout the packaging process, which is highly detrimental for wear of both the seal and the impeller.
The selective sealing contact according to the invention reduces the wear and tear on both the impeller and, most importantly, the seal member, extending their lifespan.
Furthermore, when the seal member 25 is in the opening position, it does not impede the rotation of the impeller 16, leading to more efficient operation of the compressor device 13; this results in lower energy consumption and improved overall performance of the packaging machine 1.
In summary, cleanability, hygiene and durability of compressor device 13, and therefore of pressurization system 12 and packaging machine 1 are significantly improved.
Clearly, changes may be made to compressor device 13 as described herein without, however, departing from the scope of protection as defined in the accompanying claims.

Claims

Compressor device (13) for a pressurization system (12) of a packaging machine (1) configured to produce sealed packages (2) containing a pourable product starting from a tube (3) of packaging material, the compressor device (13) being configured to suction air from an isolation chamber (10) of the packaging machine (1) designed to contain sterile and/or aseptic air, to pressurize the suctioned air, and to deliver the pressurized air towards said tube (3),
the compressor device (13) comprising an impeller (16) and a casing body (17), wherein the casing body (17) internally defines an impeller vane (18) and a receiving seat (19) for the impeller (16), the impeller (16) and the receiving seat (19) being separated by a gap (24) which fluidically connects the impeller vane (18) with an external environment (50) outside of the compressor device (13) for allowing the passage of air in overpressure from the impeller vane (18) through the gap (24) and towards the external environment (50);

wherein the compressor device (13) comprises a seal member (25) arranged at said gap (24), the seal member (25) being configured to be controlled in:
- an opening position, in which it delimits a passage together with said impeller (16) and/or said receiving seat (19) for allowing the passage of air in overpressure through the gap (24); and

- a closing position, in which it fluid-tightly seals the gap (24).
Compressor device (13) as claimed in claim 1, wherein the seal member (25) is carried by one of said impeller (16) and casing body (17); and wherein the seal member (25) is configured to cooperate in fluid-tight contact with the other of said impeller (16) and casing body (17) when controlled in said closing position.
Compressor device (13) as claimed in claim 2, wherein the seal member (25) is carried by the casing body (17) at said receiving seat (19); and wherein the seal member (25) is configured to abut in fluid-tight manner against the impeller (16) for closing and sealing the gap (24) when controlled in said closing position.
Compressor device (13) as claimed in claim 3, wherein the impeller (16) has a longitudinal axis (A) and includes a shaft (22), which extends along the longitudinal axis (A) and engages the receiving seat (19), and a bladed body (23), which is carried by the shaft (22), develops about the longitudinal axis (A) and is arranged in the impeller vane (18);
wherein the seal member (25) is configured to abut against the shaft (22) when controlled in said closing position.
Compressor device (13) as claimed in claim 4, wherein the receiving seat (19) includes a recess (26) facing the shaft (22) along a radial direction, relative to the longitudinal axis (A);
and wherein the seal member (25) is arranged within the recess (26) when controlled in said opening position and is configured to abut against the shaft (22) when controlled in said closing position, so that the abutment direction of the seal member (25) is parallel to the radial direction.
Compressor device (13) as claimed in claim 3, wherein the impeller has a longitudinal axis (A) and includes a shaft (22), which extends along the longitudinal axis (A) and engages the receiving seat (19), and a bladed body (23), which is carried by the shaft (22) and develops about the longitudinal axis (A);
wherein the sealing member (25) is configured to abut against the bladed body (23) when controlled in said closing position.
Compressor device (13) as claimed in claim 6, wherein the bladed body (23) includes a front portion (23a), which carries a plurality of blades and is arranged in the impeller vane (18), and a rear portion (23b), which extends from the shaft (22), supports the front portion (23a) and faces the receiving seat (19);
wherein the casing body (17) includes a recess (26) facing the rear portion (23b) along an axial direction, parallel to the longitudinal axis (A);

and wherein the seal member (25) is arranged within the recess (26) when controlled in said opening position and is configured to abut against the rear portion (23b) of the bladed body (23) when controlled in said closing position, so that the abutment direction of the seal member (25) is parallel to the axial direction.
Compressor device (13) as claimed in any one of the foregoing claims, and comprising an actuator device configured for controlling the seal member (25) between the opening position and the closing position.
Compressor device (13) as claimed in claim 8, wherein the seal member (25) is made of an elastomeric material, is hollow and internally defines an inflatable chamber (27);
wherein the actuator device includes a pneumatic circuit (28) configured to selectively:
- supply gas into the inflatable chamber (27) for determining an inflation of the seal member (25) thereby controlling the seal member (25) in said closing position;

- suction air from the inflatable chamber (27) for determining a deflation of the seal member (25) thereby controlling the seal member (25) in said opening position.
Compressor device (13) as claimed in claim 9, and comprising a pressure sensor (29) configured to detect a pressure within the inflatable chamber (27).
Compressor device (13) as claimed in claim 8, wherein the actuator device includes mechanical or electromechanical or magnetic or electromagnetic means for controlling the seal member (25) between the opening position and the closing position.
Compressor device (13) as claimed in any one of the foregoing claims, wherein the seal member (25) has a substantially D-shaped cross section or a substantially W-shaped cross section.
Pressurization system (12) for a packaging machine (1) configured to produce sealed packages (2) containing a pourable product starting from a tube (3) of packaging material, the pressurization system (12) comprising:
- a compressor device (13) as claimed in any one of the foregoing claims and configured to suction air, by means of an inlet duct (13a) thereof, from an isolation chamber (10) of the packaging machine (1) designed to contain sterile and/or aseptic air, to pressurize the suctioned air, and to deliver the pressurized air, by means of an outlet duct (13b) thereof, towards said tube (3) ;

- a gas feeding duct (14) fluidically connected to the outlet duct (13b) of the compressor device (13) and designed to feed the pressurized air into the tube (3); and

- a delimiting element (15) connected to the gas feeding duct (14), configured to be arranged within the tube (3) for dividing the tube (3) in a first space (3a) being in fluidic connection with the isolation chamber (10) a second space (3b) being arranged downstream of the first space (3a) and configured to receive the pressurized air from the gas feeding duct (14).
The pressurization system (12) according to claim 13, being operable in:
- an operational configuration in which the impeller (16) rotates and the seal member (25) is controlled in the opening position thereby allowing the passage of air in overpressure through the gap (24), and

- a cleaning configuration in which the impeller (16) is stopped from rotating, the seal member (25) is controlled in the closing position, the impeller vane (18) is fed with a cleaning medium and the seal member (25) is configured for preventing the cleaning medium to leak out through the gap (24).
Packaging machine (1) configured to produce sealed packages (2) containing a pourable product starting from a web (4) of packaging material, the packaging machine (1) comprising:
- conveying means configured for advancing the web (4) ;

- a web folding device (5) configured for folding the web (4) into a tube (3);

- a sealing device (6) configured for longitudinally sealing the tube (3);

- a filling system (8) configured for supplying pourable product into the tube (3);

- an isolation chamber (10) configured to contain sterile and/or aseptic air;

- a forming and sealing unit (7) configured for repeatedly forming and transversally sealing the tube (3) at successive cross-sections thereof, thereby obtaining a plurality of packs (2a) from which the packages (2) are subsequently obtained;

- a pressurization system as claimed in claim 14,

- a cleaning medium supplier, configured to supply a cleaning medium to the impeller vane (18), with the pressurization system (12) being set in the cleaning configuration.
Method for producing sealed packages (2) containing a pourable product starting from a web (4) of packaging material, the method comprising the following steps:
- advancing the web (4) of packaging material;

- folding the web (4) into a tube (3);

- longitudinally sealing the tube (3);

- supplying the pourable product into the tube (3); wherein a delimiting element (15) is arranged within the tube (3) for dividing the tube (3) in a first space (3a) being in fluidic connection with an isolation chamber (10) containing sterile and/or aseptic air and a second space (3b) being arranged downstream of the first space (3a) along a tube advancement path;

- through a compressor device (13), suctioning air from the isolation chamber (10), pressurizing the suctioned air, and delivering the pressurized air to a gas feeding duct (14),
wherein the compressor device (13) comprises an impeller (16) and a casing body (17), wherein the casing body (17) internally defines an impeller vane (18) and a receiving seat (19) for the impeller (16), the impeller (16) and the receiving seat (19) being separated by a gap (24) which fluidically connects the impeller vane (18) with an external environment (50) outside of the compressor device (13) for allowing the passage of air in overpressure from the impeller vane (18) through the gap (24) and towards the external environment (50),

wherein the compressor device (13) comprises a seal member (25) arranged at said gap (24),

- feeding pressurized air from the gas feeding duct (14) into the second space (3B);

- forming and transversally sealing the tube (3) at successive cross-sections thereof, thereby obtaining a plurality of packs (2a) from which the packages (2) are subsequently obtained,
wherein during the above mentioned steps, the seal member (25) is controlled in an opening position, in which it delimits a passage together with said impeller (16) and/or said receiving seat (19) for allowing the passage of air in overpressure through the gap (24);

wherein the method further comprises the steps of:

- moving the seal member (25) into a closing position, in which it fluid-tightly seals the gap (24),

- with the seal member (25) being in the closing position, feeding a cleaning medium within the impeller vane (18).