WO2025132107A1

WO2025132107A1 - Leak testing method and station for containers and filling method and line for such containers

Info

Publication number: WO2025132107A1
Application number: PCT/EP2024/086340
Authority: WO
Inventors: Filippo Furlotti
Original assignee: IMA Industria Macchine Automatiche SpA
Current assignee: IMA Industria Macchine Automatiche SpA
Priority date: 2023-12-18
Filing date: 2024-12-13
Publication date: 2025-06-26
Anticipated expiration: 2026-06-18

Abstract

A leak testing station (50) for containers (C) accommodated in respective transport pucks (3), characterized in that it comprises a testing carousel (51) that can rotate with continuous motion about a central axis (L) and which comprises a plurality of testing devices (5), each one of which comprises: - a movable bell (53) which is adapted to engage directly the puck (3) so as to form a chamber (67) containing said container (C); - an opening (38) which is in fluid communication with the interior of the puck (3), with the vacuum generation means (54) and with the detection means (55); - inside the bell (53), tracer gas injection means (59) which are adapted to engage, in a gas-tight manner, the intake (30) of the container (C) in the chamber (67).

Description

LEAK TESTING METHOD AND STATION FOR CONTAINERS AND FILLING METHOD AND LINE FOR SUCH CONTAINERS

The present invention relates to a method and a station for testing the seal of containers, particularly for batteries to be filled with electrolyte, for example with a dense liquid, a semi-liquid (gel), or with any fluid. The invention also relates to a method and a line for filling such containers, in particular with electrolyte, that comprises such testing method and such testing station, respectively.

In the sector of filling containers with liquids, semi-liquids or gases, a test may be required of the seal of the container before operations to fill it.

This test is critically important for containers of batteries to be filled with an electrolyte, considering the risks that a spill of electrolyte can entail.

In fact, the electrolytes used for batteries, which can be in the form of liquids or gels, have highly corrosive properties, so much so that an accidental leak of such an electrolyte would result in injury to bodies present in the surrounding environment, as well as a drop in performance of the battery. Furthermore, electrolytes are highly inflammable in non-dry environments.

The aim of the present invention is to devise a testing method and to provide a testing station capable of identifying defective containers that cannot guarantee complete gas-tightness.

Within this aim, an object of the invention is to devise a testing method and to provide a testing station capable of standalone operation and/or operation as part of a filling line.

In particular, an object of the invention is to perform seal testing in a line for continuous production of batteries, without stopping the containers or slowing down production speed.

A specific object of the invention is to execute the above-mentioned test while keeping the bulk of the testing station substantially low, for example by using continuously -rotating carousels with diameter and number of devices that are commonly used in the sector of filling lines that use carousels.

Furthermore, the present invention sets out to overcome the drawbacks of the background art in a manner that is alternative to any existing solutions.

Another object of the invention is to provide a testing method and station that are highly reliable, easy to implement, and at low cost.

This aim and these and other objects which will become better apparent hereinafter are achieved by a method according to claim 1, optionally provided with one or more of the characteristics of the dependent claims.

The aim and the objects of the invention are likewise achieved by a testing station according to claim 9, optionally provided with one or more of the characteristics of the dependent claims.

The aim and objects of the invention are likewise achieved by a method and a filling line according to claims 6 and 11, respectively.

Further characteristics and advantages of the invention will become better apparent from the description of preferred, but not exclusive, embodiments of the invention, illustrated by way of non-limiting example in the accompanying drawings characterized in that:

Figure 1 is a plan view from above of a testing station according to the invention;

Figure 2 is a perspective view of the testing station shown in Figure 1;

Figure 3 is a cross-sectional view of a portion of the testing station shown in Figure 1 and taken along the line III-III;

Figure 4 shows a filling line provided with a testing station according to the invention;

- Figures 5a-5b show respectively the path of the containers and the path of the filling units in the line of Figure 4; - Figure 6 is a perspective view of a filling kit that can be used in the filling line in the previous figures;

- Figure 7 is an axial cross-sectional view of the kit of Figure 6;

- Figure 8 corresponds to the previous figure while the filling unit is being fixed to the puck that accommodates the container;

- Figure 9 corresponds to the previous figure with the fixing means activated to form a unitary assembly;

- Figure 10 is a perspective view of the unitary assembly at the end of filling the container with electrolyte.

With reference to the figures, the leak testing station for containers C, generally designated by the reference numeral 50, is configured preferably for closed containers that have an intake 30, in particular an upper intake 30, as the only point of access to the inside of the container. Through the respective intake 30, the containers C can be filled with a fluid in a filling line 1 (in particular, they can be filled with an electrolyte). When such intake 30 is sealed, the interior of the container C should be completely gastight, unless there are defects present.

The containers C are preferably containers for electrochemical cells, or batteries, in particular for secondary cells such as, for example, lithium- ion cells or batteries. The cells can be, for example, cylindrical or prismatic cells.

The containers C arriving at the testing station 50 are accommodated in respective transport pucks 3, which are preferably beaker-like trays that leave the intake 30 exposed upwards.

The containers C arrive at the testing station 50 one after the other, and each one inside its own puck 3. The arriving containers C preferably contain the electrodes of the electrochemical cell, for example a so-called "jelly roll".

The testing station 50 extends along a predefined path for the pucks 3 and, as a consequence, for the containers C, which path transits along the circumference traced by a testing carousel 51 interposed between two transfer starwheels 52 and 106.

In more detail, the testing carousel 51 is designed as a circular array in order to be able to simultaneously handle a plurality of pucks 3 which are continuously supplied by the first transfer starwheel 52 and removed by the second transfer starwheel 106.

In this manner, the entire process of testing the individual container C is performed during the continuous rotation of the testing carousel 51.

According to the invention, the testing carousel 51 comprises a plurality of individual testing devices 5 along its periphery, each one of which can be associated temporarily with a respective puck 3 conveyed by the testing carousel 51. The testing devices 5, which are integral in rotation with the carousel 51, are equidistant from the central rotation axis L of the testing carousel 51 and are arranged at regular intervals along the circumference of such carousel. Each testing device 5 preferably comprises:

- a bell 53 which can be associated in a gas-tight manner with the puck 3, in order to define a chamber 67 between the bell 53 and the puck 3. This chamber 67 can be associated with vacuum generation means 54 and is also functionally connected to tracer gas detection means 55, for the detection of any presence of said tracer gas inside the chamber 67;

- injection means 56 which can be associated, in a gas-tight manner, with the upper intake 30 of the container C and are configured to inject a tracer gas exclusively into the container C, for example helium, for a preset time or until a preset pressure inside the container C is reached.

Each bell 53 can move (in a direction substantially parallel to the axis of rotation L of the testing carousel 51) toward or away from a respective supporting base 37 (for supporting the puck 3) which is integral with the carousel 51 in the rotation of the latter. By moving toward said base 37, the lower portion of the bell 53 is coupled in a gas-tight manner with the upper

which can engage the base of the bell 53, as illustrated in Figure 3.

In the preferred embodiment, the bell 53 can be coupled to the puck 3 by means of an actuator that moves the bell 53 toward the puck 3 until it engages said puck after it is transferred to the testing carousel 51.

The vacuum generation means 54 comprise an aspirator or a vacuum pump, not shown, in communication with the supporting base 37 and, through this base, with the internal volume of the chamber 67 by means of a vacuum valve 57, which is in communication with a through hole 34 defined in a base 33 of the puck 3.

At the base 33 of the puck 3, in the supporting base 37, an opening 38 is provided which is positioned so as to be in fluid communication with the hole 34 in the puck 3 (when the puck is transported by the carousel 51), with the vacuum valve 57 and with the detection means 55. The opening 38 can comprise a hollow plunger 58 which is coaxial thereto and shaped so as to adhere to the through hole 34 and so as to place the puck 3 in communication with the vacuum valve 57 and/or the detection means 55.

Similarly, the injection means 56 comprise an injection plunger 59 which is accommodated inside the bell 53 and can move coaxially with respect to the bell 53 between a position of disengagement from the container C, in which the upper intake 30 is free from obstructions so as to communicate with the internal volume of the chamber 67, and a position of engagement with the container C, in which the upper intake 30 is in communication (in a gas-tight manner with respect to the outside of the container C) with an injection channel 60 defined inside the injection plunger 59.

The injection channel 60, which comes out toward the supporting base 37 so as to lead to the intake 30, is surrounded by sealing means 39 (for example, an axial sealing ring) which are adapted to engage the container C around the intake 30 in order to prevent the leakage of the tracer gas from the injection channel 60 and from the intake 30 toward the chamber 67. The injection channel 60 is connected, in turn, with a circuit for supplying tracer gas by means of a gas inlet valve 61.

Between the inside of the bell 53 and the outside of the injection plunger 59, a radial gasket 66 is provided, which is adapted to prevent leaks of gas from the chamber 67.

Conveniently, the injection means 56 further comprise a first venting valve 63 which is adapted to evacuate the tracer gas from the chamber 67 once the testing method has concluded.

Advantageously, the detection means 55 comprise a detector or “sniffer”, located on a venting conduit 64 of the puck 3 and interposed between the through hole 34 and a second venting valve 65 which is adapted to restore the internal pressure of the chamber 67 once the testing method has concluded.

As mentioned previously, the testing carousel 51 comprises a plurality of the testing devices 5 described above, so as to handle the containers C arriving from the first transfer starwheel 52 continuously and in sequence.

Conveniently, in order to enable the removal of defective containers 3, bypass and/or pickup means can be provided which are configured to make the puck 3 containing the container C found to be defective drop out from the path.

With reference to what has been described so far, in general the testing method according to the invention entails the following steps:

1. feeding the pucks 3 in sequence to the testing carousel, so that each arriving puck is received onto the supporting base 37 around the carousel 51;

2. and, during the continuous rotation of the carousel 51:

- in a gas-tight manner, engaging each bell 53 with the puck 3 arranged on the respective supporting base, so that the container C in the puck 3 is accommodated in a respective chamber 67 enclosed between the bell 53 and the puck 3. In this condition, the upper intake 30 of the container C is in fluid communication with the chamber 67;

- generating a vacuum in the chamber 67 by means of the vacuum generation means 54, so as to remove the air and/or other gases present in the chamber 67 and, therefore, also in the container C;

- following the step of generating the vacuum, lowering the plunger 59 toward the supporting base 37 and injecting the tracer gas exclusively into the respective container C through the upper intake 30;

- while the intake 30 of the container C is kept sealed from the outside by the sealing means 39, detecting any traces of the tracer gas in the venting conduit 64 using the detection means 55;

- venting the container C and moving the bell 53 away from the supporting base 37, so as to then hand over the container C to the starwheel 106.

In this manner, considering that the sole intake 30 is sealed with respect to the chamber 67 by the engagement between the plunger 59 and the intake, any tracer gas detected by the sniffer 55 must necessarily have leaked from another part of the container or from a defect in the intake 30. As a consequence, the container C has a manufacturing defect and will therefore be discarded downstream as defective.

Advantageously, the testing station 50 can be inserted in a filling line 1 as shown in Figures 4, 5a and 5b.

In more detail, as will be better described below, the testing station 50 can be inserted upstream of a filling station 13 along a portion of a first path Pl between an inlet 10 and a coupling station 14.

The filling line 1 comprises a first path Pl for conveying a series of containers C to be filled, which are conveyed, preferably with continuous motion, from an inlet 10, where containers C to be filled enter the line 1, to an outlet 11 , from which containers C filled with a predetermined volume of fluid (herein also designated C) exit from the line 1. The inlet 10 and the outlet 11 are respectively passed through by per se known linear conveyors 10a and I la, for example belt conveyors, chain conveyors or screw feeders.

The filling fluid can be any liquid or semiliquid, and may be dense and/or viscous. The invention is however particularly suitable for filling with fluids that are introduced slowly into the container C, owing to the particular density/viscosity of the fluid or owing to the presence of obstacles and/or interspaces inside the container that slow down its filling.

The container C can also be of any type, but in particular it can be of the type that comprises a plurality of obstacles, cells and/or interspaces inside it that slow down the filling of the container with the fluid.

In the preferred embodiment of the invention, the fluid is an electrolyte for batteries, for example an electrolytic gel, while the container C supplied at the inlet 10 is a container for batteries (for example, for cylindrical, prismatic, or pouch cells) which internally has anode and cathode sheets and optionally other materials and components that take up space inside the container C, obstructing what would otherwise be a rapid introduction of the electrolyte. The container C can have a cylindrical shape with a circular base, as in the case shown in the drawings, or a prismatic or pouch shape, in which the sheets of anode, cathode and other materials (for example insulators), not shown, are rolled to form a single multilayer roll inside the container C.

Each container C along the first path Pl is accommodated in the respective transport puck 3, which is a beaker-like body that is open above at a rim 31 thereof so as to allow the container C to be slid (automatically) into the puck through the rim 31, leaving the upper intake 30 thereof exposed, and to be stabilized during the various operations along all of the first conveyance path Pl. The puck 3 is preferably suitable to remain integral with the container C along all of the first path Pl, by interference-fit coupling and/or by form-fit coupling with the external surface of the container C, but leaving preferably at least one lateral interspace 36 in order to allow the creation of a vacuum in the container C before its filling and/or in order to allow the washing of the container C before and/or after it is filled with the fluid. For example, the puck 3 can also have a substantially cylindrical shape, and the container C is preferably accommodated in the puck 3 so that it does not protrude above the rim 31.

The puck 3 can have on its lateral surface a fixing surface, for example in the form of at least one depression 32 which, in the embodiment illustrated, is coaxial with the central axis of the puck and advantageously annular. The fixing surface 32 is preferably arranged proximate to the upper rim 31 of the puck 3.

On the end axially opposite to the rim 31 the puck 3 has _the base 33 which is suitable to give internal support to the container C and/or in any case to provide a resting surface outward, used for conveying the puck - and therefore the container C - along at least the first conveyance path Pl or some sections thereof. The base 33 is provided with the through hole 34, for example in the center.

The lateral surface of the puck 3 can have an enlarged radial portion 35 which substantially acts as a radial spacer when the pucks are arranged side-by-side, in particular in the buffer station 110 described below.

The filling line 1 also comprises a second conveyance path P2 for a series of filling units 2.

The filling units 2 are substantially faucets that can move with continuous motion along the second path P2, which is preferably a closed path and in any case is at least partially superimposed on the first conveyance path Pl so that, in the superimposed segments, the filling units 2 and the respective containers C are mutually superimposed in an axial direction, i.e. parallel to a (vertical) direction that is substantially perpendicular to the floor on which the line 1 is installed.

Each filling unit 2 substantially comprises a syringe-like body, provided with a reservoir 21 which is adapted to contain, in an internal first chamber 21a thereof, the predetermined volume of fluid (for example electrolyte) to be transferred to a respective container C. To this end, this reservoir 21 comprises a bottom opening 20 for the passage of the fluid, which can, although not necessarily, have a diameter in the order of a few millimeters (for example 2-3 mm) and which can advantageously be connected to the upper intake 30 of the respective container C, for example by making the opening 20 with a spout 20a protruding outward from the reservoir 21.

In the embodiment illustrated, the reservoir 21 is associated with a plunger 22, which can move axially with respect to the reservoir 21 by way of a guide body 24 which is fixed to the reservoir 21, for example, with a flanged coupling as in the embodiment shown. In particular, the guide body 24 of the plunger 22 is provided with a tubular guide 242 which is coaxial, but external, to the reservoir 21 and in which the plunger 22 is associated so that it can slide.

The plunger 22 comprises a piston 23 which is fixed thereto or integrated therewith, and which can slide with a gas-tight seal along the internal side walls of the reservoir 21 and divides the internal space of the reservoir into the first chamber 21a for containing the fluid to be transferred to the container C and into a second chamber 21b for containing a gas under pressure (for example air) which is suitable to move, through an expansion thereof, the piston 23 in a direction that expands the volume of the second chamber 21b and, simultaneously, decreases the volume of the first chamber 21a of the reservoir 21, in this manner making the fluid exit from the opening 20. To this end, the plunger 22 comprises an internal coaxial channel 25 which is connected to the second chamber 21b and which, at the other end along the axis of the plunger 22, is closed with a one-way valve (not shown), which can be opened mechanically only in order to introduce or vent the gas in the second chamber 21b of the reservoir 21.

The kit formed by the filling unit 2 and by the respective puck 3 also comprises means for removable fixing 27, which are suitable to render the filling unit 2 and the puck 3 temporarily mutually integral, and thus to form a unitary assembly 4 such as, for example, the one shown in Figures 9-10.

The means for removable fixing 27 are preferably associated with each filling unit 2, as in the embodiment shown, but they can, alternatively, be provided on the puck 3, if any.

The means for removable fixing 27 can be provided with one or more claws 271 , for example with a grapple formed by a plurality of said claws 271 which can be moved closer to/away from each other about the central axis of the filling unit 2.

In other embodiments, not shown, the means for removable fixing can perform the fixing using other snap-acting coupling means, either by interference fit or by friction (for example, with a threaded coupling).

In the embodiment shown, each claw 271 is a rocker with a fulcrum 276, for example provided on a respective pair of lugs 26a-26b which protrude from the reservoir, so as to oscillate with respect to a horizontal axis. Each claw 271 can have, at one end, a barb 272 which is adapted to grip the depression 32 of the puck 3.

Each claw 271 can further be pivoted to a respective link rod 273 at the opposite end of the arm with respect to the fulcrum 276. The link rod

273 is in turn hinged on a respective hinge eyelet 277 of a driving slider 274 which can move advantageously in a direction coaxial to the filling unit 2. For example, in the embodiment the driving slider 274 is fitted on the tubular guide 242 so as to be able to slide axially toward/away from the reservoir 21, i.e. with respect to the flanging of the guide body 24 fixed to the latter.

The mutual approach and spacing apart between the driving slider

274 and the guide body 24 along an axial direction result in, respectively, the decoupling and the fixing between the filling unit 2 and the puck 3, i.e. respectively the mutual spacing apart and approach of the hooks 272 of the claws 271 along respective axial planes. Furthermore, elastic return means are preferably provided for keeping the fixing means 27 elastically loaded in a locked condition with respect to the puck 3. This makes it possible to couple by snap action the filling unit 2 with the puck 3 (if any) or with the container C, simply by bringing them together in an axial direction and thus obtaining the unitary assembly 4.

In the preferred, but not exclusive, embodiment of the invention, in which the fixing means 27 are implemented with a grapple, the locked condition is a condition of minimum mutual distance between the hooks 272 with respect to the central axis of the filling unit 2 while the elastic return means consist substantially of compression springs 275, which are interposed between the driving slider 274 and the guide body 24 so as to oppose a mutual approach between the driving slider 274 and the guide body 24.

The driving slider 274 is advantageously implemented with a multi- lobed plate, so that the compression springs 275 are interposed between respective lobes of the slider 274 and the guide body 24. The lobes of the driving slider 274 are, furthermore, optionally offset with respect to the eyelets 277 for hinging the link rods 273, so that the region between one lobe and the next does not obstruct the movement away from the guide body 24 of the pivoting point of the link rods 273 with the respective claw 271.

According to a particular aspect of the invention, the conveyance paths Pl and P2 pass through an assembly 100 for producing filled containers C (filled with a predetermined volume of fluid) and a buffer station 110.

The production assembly 100 comprises a separation station 12, a filling station 13 for filling the filling units, downstream of the separation station (with respect to the direction of transport of the filling units 2, represented by the arrows of the second path P2), and a coupling station 14 downstream of the filling station 13. The stations 12-14 comprise respectively at least one separation carousel 120, at least one filling carousel 130 and at least one coupling carousel 140, each one being able to rotate, preferably with continuous motion, about a central rotation axis 121, 131, 141, respectively.

Each carousel 120, 130, 140 is provided with a plurality of grip means 122, 132, 142 which are arranged along the peripheral region and are suitable to hold at least a respective one of the filling units 2 (based on the embodiment considered) during the rotation of the respective carousel. The grip means 122, 132, 142 are mutually angularly equidistant about the respective central rotation axis 121, 131, 141 so as to form a circumference. The pitch of the grip means 122, 132, 142 about the respective central rotation axis 121, 131, 141 is preferably equal for all the carousels.

Carousels with grip means along their circumference are per se well known in the bottling sector.

Advantageously, transfer starwheels 101-106 are also provided upstream and downstream of each one of the carousels 120, 130, 140 (with respect to the direction of transport of the path Pl and/or P2). The transfer starwheels 101-106 are also rotating, preferably with continuous motion, about a respective rotation axis parallel to the central rotation axes 121, 131, 141 of the carousels 120, 130 and 140. The transfer starwheels 101-106 can be of the type with receptacles arranged at a constant pitch about the rotation axis of the respective starwheel, in order to entrain the object received from the upstream carousel or conveyor and give it to the downstream carousel or conveyor.

Intermediate transfer starwheels 102 and 103 are interposed, respectively, between the carousels 120 and 130 and between the carousels 130 and 140, in order to transfer at least the filling units 2 between one carousel and the next.

A first inlet starwheel 101 (with respect to the direction of transport of the second path P2) is provided upstream of the separation carousel 120 and downstream of an unloading conveyor 108 for the unitary assemblies 4 which connects the outlet of the buffer station 110 to the production assembly 100 in order to return the unitary assemblies 4 after the corresponding containers C are filled.

A second inlet starwheel 106 is, instead, arranged downstream of the linear conveyor 10a and preferably upstream of the coupling carousel 140 (with respect to the direction of transport of the first path Pl), in order to feed the containers C to be filled, accommodated in the respective puck 3, to the coupling carousel 140. Alternatively, the second inlet starwheel 106 can be located upstream of the filling carousel 130 (with respect to the direction of transport of the first path Pl).

Such second inlet starwheel 106 corresponds to the second transfer starwheel of the testing station 50.

A first unloading starwheel 105 (with respect to the direction of transport of the second path P2) is provided downstream of the coupling carousel 140 and upstream of a feeding conveyor 107 for feeding the unitary assemblies 4 to the buffer station 110.

A second unloading starwheel 104 is instead arranged (with respect to the direction of transport of the first path Pl) downstream of the separation carousel 120, and upstream of the unloading conveyor I la for unloading the filled containers C, optionally accommodated in the respective pucks 3.

The first conveyance path Pl and the second conveyance path P2 comprise arcs of circumferences traced ideally by the grip means 122, 142 and, for P2, 132 with their rotation about the respective central rotation axes 121, 141 and 131. Arcs of the first and of the second path Pl and P2 are superimposed preferably along the circumferences traced ideally by the grip means 122 and 142 respectively of the separation carousel 120 and of the coupling carousel 140.

Other superimposed segments between the first and the second path Pl and P2 are provided along the buffer station 110 and along the feeding 107 and unloading 108 conveyors for the unitary assemblies 4 to/from the buffer station 110.

The grip means can be for example in the form of a gripper. In the separation carousel 120, the grip means 122 can be formed by two pairs of grippers superimposed in a direction parallel to the rotation axis 121, so as to grasp respectively the filling unit 2 and the container C (or the puck 3, if any) of the unitary assembly 4. Such pairs of grippers can be mutually movable in an axial direction (for example using a jack associated with each pair of superimposed grippers) in order to mutually space the filling unit 2 and the container C apart, or keep them separate from each other.

Advantageously, the grip means 122 or a suitable sloped cam fixed around the central axis 121 of the separation carousel 120 can comprise a thrust surface which is adapted to push the driving slider 274 toward the guide body 24 and so open the claws 271, allowing the separation of the filling unit 2 from the rest of the unitary assembly 4 during the rotation about the axis 121.

Also in the coupling carousel 140, the grip means 142 can be formed by two pairs of grippers superimposed in a direction parallel to the rotation axis 141, so as to grasp respectively the filling unit 2 and the puck 3 (or the container C) and such pairs of grippers can be mutually movable parallel to the rotation axis 141 (for example using a respective jack) in order to bring the filling unit 2 and the respective container C mutually together in an axial direction, so as to form the unitary assembly 4 in which the filling unit 2 and the respective container C are in fluid communication. If the fixing means 27 are of the snap-fit type, as in the example of the grapple illustrated, the unitary assemblies 4 are obtained by simply moving them closer to each other as above.

The coupling station 14 can also comprise means for pressurizing the filling units 2 which are adapted to open the one-way valve of the internal channel 25 and inject a gas under pressure (for example air) into the second chamber 21b which would gradually expand the second chamber 21b by making the plunger 23 translate toward the bottom of the reservoir 21.

Upon releasing the filling units 2 from the coupling station 14, the one-way valve will be closed, so trapping the gas under pressure in the second chamber 21b.

In an alternative embodiment, it is possible to have the means for pressurizing at the buffer station 110, by providing thereon a plurality of pressure taps which are automatically connected to the plungers 22 of the unitary assemblies 4 which are in transit at the accumulator 110. The pressure taps are then automatically removed before the unitary assemblies exit from the accumulator 110.

In other, alternative embodiments of the invention, the plunger 22 can be actuated electrically (for example, with a linear motor) or mechanically (for example, using springs or using inclined cam surfaces that interact with the plunger 22 in order to move it axially while the unitary assembly is moved forward in the buffer station 110) instead of with a pneumatic actuation obtained with the expansion of the gas.

The filling station 13 comprises, at each grip means 132, means for introducing a predetermined volume of fluid into the filling unit, in particular comprising a faucet and a filling nozzle for each grip means 132, which are connected to a main reservoir of the line 1 containing the fluid with which to fill the containers C. The faucets and the filling nozzles are mounted along the peripheral region of the filling carousel 130 so as to rotate integrally with such carousel about its own central rotation axis 131. The filling nozzles can be mounted under the grip means 132 and oriented upward, so as to be able to mate with the bottom opening 20 of the filling unit 2 held by the respective grip means 132.

In transferring the predetermined volume of fluid from the filling nozzle to the filling unit 2 the first chamber 21a thereof is gradually filled with the fluid, consequently moving the plunger 23 in the direction that reduces the volume of the second chamber 21b. The buffer station 110 is arranged along a superposition segment of the paths Pl and P2 which goes from the coupling station 140 to the separation station 120 and is associated with the feeding 107 and unloading 108 conveyors of the unitary assemblies 4 which respectively feed the unitary assemblies 4 to, and unload them from, the buffer station 110 at the production speed of the line 1.

The buffer station 110 is an accumulator of the FIFO (First In, First Out) type and can be an accumulation table or an assembly of accumulator conveyors. The FIFO accumulator can have one or more moving pads, conveyor belts, motorized roller conveyors or sliding surfaces, optionally arranged so as to form a serpentine route and in any case a route suitable to accumulate a (large) number of unitary assemblies 4 (in particular, N * t unitary assemblies, where N is the production speed of the line 1 in terms of containers per minute and t is the time - in minutes - to fill the individual container C with the predetermined volume of fluid), by distributing them over an ample surface or making them travel tortuous and/or lengthened paths in order to make them remain in the buffer station 110 for the length of time necessary for the containers C of the unitary assemblies to be filled with the respective predetermined volume of fluid.

The accumulator tables or the accumulator conveyors are per se known, for example from the patent US 5,282,525 or from the patent EP 1144285.

The unitary assemblies 4 arrive at the buffer station 110 preferably continuously, in a neat row and optionally mutually spaced apart with the same pitch as that between the grip means 122, 132, 142 of the carousels and between the receptacles of the transfer starwheels 101-106.

The buffer station 110 is adapted to advance the unitary assemblies 4 arriving from the feeder conveyor 107 toward the unloading conveyor 108, at a speed and on a path length defined by the time (t) necessary to fill the individual container C with the predetermined volume of fluid. Such incoming unitary assemblies 4 each comprise the filling unit 2 substantially filled with the predetermined volume of fluid and the container C not yet filled with such volume.

With the pressure exerted by the gas inside the second chamber 21b, the volume of fluid is slowly transferred to the container C of the unitary assembly 4 which can continue to remain on the accumulator table for as long as necessary to complete the transfer of the volume of fluid from the filling unit 2 to the container C of the unitary assembly 4.

By virtue of the buffer station 110, the production assembly 100 can operate at high production speeds N (for example, between 100 and 600 containers C per minute), by being able to rapidly fill the filling units 2 with a carousel 13 that has a limited number of grip means 132 and filling nozzles (for example, in the order of a few multiples of ten, for example between 30 and 60). At the buffer station 110, each filling unit 2 will then autonomously fill, in the (longer) time t required by the internal characteristics of the container C and/or by the nature of the fluid, the respective container C of the unitary assembly 4, by transferring to the container C over time t (for example 10 minutes) the predetermined volume of fluid that the filling unit 2 had received in a much shorter time (for example 5 seconds) from the filling station 13 of the production assembly 100. The filling station 13 can therefore have a relatively small number of filling nozzles and faucets (for example between 30 and 60 on the carousel 130).

The operation of the invention is evident from the foregoing description.

The containers C are transported in series inside the respective pucks 3 along the first conveyance path Pl between the inlet 10 and the outlet 11 of the production assembly 100, with continuous motion and at a certain desired (high) production rate N corresponding to the rate of the production line in which the filling line 1 is inserted. For example, the speed N with which the filled containers C exit from the outlet 11 of the production assembly 100 is a few hundred containers per minute (for example, between 100 and 600 per minute).

Immediately after the inlet 10, the pucks 3 follow the predefined path of the testing station 50. The pucks 3 can have a bar code or other (optical) identifier so as to identify the containers C detected as defective in the testing station 50 and discard them immediately or at the outlet 11, preferably without associating them with the filling units 2.

Along their conveyance path Pl, the pucks 3 are fixed to respective "mobile faucets" represented by the filling units 2 which were previously filled at speed N, in the filling station 13, with the volume of fluid required to fill the container C and which are pressurized in the coupling station 14.

In particular, in the filling station 13 the filling units 2 are grasped by respective grip means 132 of the filling carousel 130 and brought to a respective filling nozzle 135, which is coupled to the opening 20 of the reservoir 21.

During the rotation of the filling carousel 130 the fluid injected into the reservoir 21 via the opening of the faucet 134 of the nozzle 135 lifts the plunger 23 up to a height determined by the quantity of fluid injected, which is determined on the basis of the predetermined quantity required in order to fill the container C. In the example shown in the drawings, the quantity of fluid is the maximum permitted, and filling the first volume 21a of the reservoir 21 consequently lifts the plunger 23 up to the stroke limit.

Subsequently, each filling unit 2 is transferred to the coupling carousel 140 (through the intermediate starwheel 103) where it is coupled to a respective puck 3, in order to form the unitary assembly 4, and to a respective pressurization needle, which injects the gas (air) under pressure into the second chamber 21b. The gas under pressure begins to make the plunger 23 descend and to transfer the fluid into the container C.

The container C then continues its journey along the path Pl, again at the production speed N of the assembly 100, while the filling unit 2 coupled thereto fills it completely with the fluid by virtue of the expansion of the gas under pressure inside the second chamber 21b. The container C remains at the buffer station 110 for the predetermined time required for it to be filled, for example at least 2 minutes. Optionally the time t to fill the container C can also comprise, in addition to the time it remains in transit in the buffer station 110, the time to convey the unitary assembly 4 along the segments of the conveyors 107 and 108, along which the filling can respectively begin and continue.

When the unitary assemblies 4 arrive at the outlet of the buffer station 110, for example when they are on the unloading conveyor 108, the respective container C has been completely filled with the predetermined volume of fluid. The unloading conveyor 108 advances the unitary assemblies 4 at the high production speed required by the production assembly 100. At the separation station 12, after having optionally vented the gas, the driving slider 274 is activated mechanically so as to separate the emptied filling unit 2 from the filled container C, and each filled container is brought by the respective grip means 122 (for example, lower) of the separation carousel 120 to the second unloading starwheel 104, which conveys them to the unloading conveyor I la.

The filling units 2 are then made to recirculate continuously in the filling line 1 along the closed path P2, along a segment thereof at which they are once again rendered temporarily integral with a respective puck 3 (so forming respective independent unitary assemblies 4) in order to be able to fill the respective container C, mainly at the buffer station 110, in a time t (which may be long) longer than that necessary to fill said filling units with the same volume of fluid in order to ensure a preset production rate N of filled containers C in output from the line 1.

Therefore it has been found that the invention fully achieves the intended aim and objects. The invention, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements. In practice, the materials used, as well as the contingent shapes and dimensions, may be any according to the requirements and to the state of the art.

The disclosures in Italian Patent Application No. 102023000026895 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, such reference signs have been inserted for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A leak testing method for containers (C), particularly containers for cells, or batteries, to be filled with electrolyte, characterized in that said containers (C) have an intake (30) through which they can be filled with a fluid, in particular an electrolyte, in a filling line, characterized in that the method comprises the following steps:

- conveying said containers (C), preferably with a continuous motion, along a predefined path;

- enclosing each one of said containers (C) in a respective chamber (67), so that said containers (C) continue to be conveyed together with said chamber (67) along part of said predefined path; and in that, during the conveyance of said containers (C) enclosed in said respective chamber (67) along said part of the predefined path, the method comprises the steps of:

- generating vacuum in each one of said containers (C) by extracting air from said chamber (67);

- after said vacuum generation step, injecting a tracer gas into each one of said containers (C) through said intake (30);

- after said tracer gas injection step, detecting any presence of said tracer gas that has leaked into said respective chamber (67).

2. The method according to claim 1, characterized in that each one of said containers (C) is conveyed, along said predefined path, accommodated in a respective puck (3); and in that, in said enclosing step, said container (C) is enclosed between the respective puck (3) and a bell (53) which moves along a closed path which comprises said part of the predefined path, said bell being engaged in a gas-tight manner with said puck (3) to form said chamber (67) along said part of the predefined path.

3. The method according to the preceding claim, characterized in that said puck (3) comprises a through hole (34) and in that, in said vacuum generation step, the air is extracted from said puck toward the outside of said chamber (67) through said through hole (34).

4. The method according to the preceding claim, characterized in that, in said detection step, said through hole (34) communicates with detection means (55).

5. The method according to one or more of claims 2-4, characterized in that said bell comprises a plunger (59) for the injection of said tracer gas, said injection plunger being movable coaxially to the bell (53), and in that said injection step comprises engaging said plunger (59) with said intake (30) in a gas-tight manner.

6. A method for filling containers (C) with a fluid in a filling line, in which said containers (C) are conveyed in series and inside respective pucks (3) along a first conveyance path (Pl) between an inlet (10) for the empty containers (C) and an outlet (11) for the containers (C) filled with said fluid, characterized in that it comprises the steps of:

- conveying along a second conveyance path (P2) a series of filling units (2), said first and second paths (Pl, P2) being partially mutually superimposed;

- along a portion of said second path (P2), filling each filling unit (2) with said predetermined volume of fluid;

- along a superposition segment of said first and second conveyance paths (Pl, P2), making each filling unit (2) temporarily integral with a respective one of said pucks (3), so as to form a unitary assembly (4) in which the filling unit (2) and the respective container (C) contained in the puck (3) are in fluid communication;

- accumulating the unitary assemblies (4) in a buffer station (110) in which the filling units (2) transfer said volume of fluid to said container (C);

- upon completion of the transfer of said volume of fluid, separating the pucks (3), containing the containers (C) thus filled, from the filling units (2) thus emptied and conveying said pucks (3) toward said outlet (11); and in that it comprises a leak testing method according to one or more of the preceding claims, said predefined path being a portion of said first path (Pl) upstream of said superposition segment.

7. The filling method according to the preceding claim, characterized in that said second conveyance path (P2) is a closed path, the filling units (2) that are filled with said volume of fluid in said filling step being the ones that were previously separated from the unitary assemblies (4) in said separation step.

8. The filling method according to one or more of claims 6-7, characterized in that the time for filling each filling unit (2) with said volume of fluid is shorter than the time (t) for transferring said volume of fluid from the filling unit (2) to the container (C).

9. A leak testing station (50) for containers (C), for the execution of the method according to one or more of claims 1-5, said containers (C) having an intake (30) and being accommodated in respective pucks (3), characterized in that the leak testing station (50) comprises vacuum generation means (54), tracer gas supply means, tracer gas detection means (55), a testing carousel (51) which can rotate, preferably with a continuous motion, about a central axis (L) and which comprises a plurality of testing devices (5) which are integral with the rotation of said testing carousel (51), wherein each one of said testing devices (5) comprises:

- a bell (53) adapted to engage directly said puck (3) so as to form a chamber (67) which contains said container (C), said bell being movable with respect to a supporting base (37) for the puck (3), said supporting base (37) being integral with the rotation of the testing carousel (51);

- an opening (38) in said supporting base (37) which is in fluid communication with the vacuum generation means (54) and with the detection means (55);

- inside said bell (53), tracer gas injection means (59) which are adapted to engage, in a gas-tight manner, the intake (30) of the container (C) in said chamber (67).

10. The leak testing station (1) according to the preceding claim, characterized in that said tracer gas injection means comprise an injection plunger (59) which can move within the bell (53), said bell (53) and said injection plunger (59) being movable in a direction that is substantially parallel to said axis of rotation (L), said injection plunger (59) comprising an internal injection channel (60) which leads to said supporting base (37), said injection plunger (59) comprising sealing means (39) adapted to engage around the intake (30) of the container (C).

11. A filling line (1) for performing the method of one or more of claims 6-8, comprising:

- an inlet (10) for pucks (3) containing empty containers (C);

- an outlet (11) for the pucks (3) with containers (C) that have been filled;

- a first conveyance path (Pl) for conveying the pucks (3) between said inlet (10) and said outlet (11); said filling line (1) being characterized in that it comprises:

- a second conveyance path (P2) for a series of filling units (2), said first and second paths (Pl, P2) being partially mutually superimposed;

- a separation station (12), a filling station (13) for filling said filling units (2) downstream of said separation station, a coupling station (14) downstream of said filling station (13) and a buffer station (110) between said coupling station and said separation station, said stations being passed through by at least said second conveyance path (P2), the first and second conveyance paths (Pl, P2) being mutually superimposed at least at said coupling station (14) and at said buffer station (110);

- at said filling station (13), means (135) for introducing a predetermined volume of a fluid to be injected into said containers (C) into each one of said filling units (2);

- said coupling station (14) being suitable to couple to each one of said pucks (3) a respective one of said filling units (2) that arrive from said filling station (13), so as to form a unitary assembly (4) in which the filling unit (2) and the respective container (C) are in fluid communication;

- actuation means (23) for actuating the filled filling units (2) of said unitary assemblies (4) in order to transfer, at said buffer station (110), said volume of fluid from the filling unit (2) to the container (C) of the respective unitary assembly (4), which at the end of the transfer will be composed of the emptied filling unit (2) and by the filled container (C); said separation station (12) being adapted to disassemble said unitary assemblies (4) that exit from the buffer station (110), separating the emptied filling units (2) from the respective filled containers (C) of each unitary assembly (4); said filling line being further characterized in that it comprises a leak testing station (50) according to one or more of claims 9-10 arranged along a portion of said first path (Pl) between said inlet (10) and said coupling station (14).

12. The filling line according to the preceding claim, characterized in that said second conveyance path (P2) is a closed path, so that the filling units (2) that are filled with said volume of fluid in the filling station (13) are the ones that arrive from the buffer station (110) through the separation station (12).

13. The filling line according to one of claims 11-12, characterized in that said separation, filling and coupling stations comprise respectively at least one separation carousel (120), at least one filling carousel (130) and at least one coupling carousel (140), each one of said carousels (120, 130, 140) being able to rotate, preferably with continuous motion, about a respective central rotation axis (121, 131, 141) and being provided with a plurality of grip means (122, 132, 142) which are angularly mutually spaced apart around the central rotation axis, said first and second conveyance paths (Pl, P2) comprising arcs of circles traced by the rotations of said grip means (122, 142) at least of the separation (120) and coupling (140) carousels about the respective central rotation axes (121, 141) of said carousels.

14. The filling line according to one or more of claims 11-13, characterized in that one or both of said filling unit (2) and said puck (3) comprises means for removable fixing (27), which can be actuated on command, said coupling station (14) being adapted to activate said means for removable fixing (27) so that the puck (3) becomes integral with the respective filling unit (2) so as to form said unitary assembly (4).

15. The filling line according to one or more of claims 11-14, characterized in that each one of said filling units (2) comprises a syringe- like body which comprises a reservoir (21) provided with an opening (20) for the passage of the fluid and at least one first plunger (23) which can move inside the reservoir (21) and which separates said reservoir into a first chamber (21a) suitable to contain the predetermined volume of the fluid and a second chamber (21b) suitable to contain a gas under pressure which is adapted to move, by means of an expansion of the gas, said first plunger (23) toward said opening (20) of the reservoir (21).