System for detecting container leaks

Abstract

A system (100) for detecting leaks of sealed containers, comprising a conveyor belt (10) arranged to convey the containers in an advancing direction (F); a pressurization system (20) arranged to press the containers against the conveyor belt (10) to apply a compressive mechanical load to the containers; a suction and measurement system (40) comprising a suction unit (41, 42, 43) configured to suck gas from the vicinity of the pressurized vessel and one or more sensors for measuring the concentration of one or more of the sucked gas; and a processing unit configured to compare the gas concentration measured by the suction and measurement system (40) with a reference gas concentration to determine whether there is a leak in the container under test. The pressurization system (20) comprises a plurality of rollers (21, 22, 23, 24) associated with a moving member (25) controlled by a control unit. The movement means (25) comprise a height translation means configured to move the rollers (21, 22, 23, 24) in the vertical direction, the rollers being independent of each other and such that the movement of the rollers can follow the shape of the container under test.

Description

Technical Field

[0001] The present invention relates to a system for detecting container leaks, the system being configured to detect leaks in sealed containers, and more specifically, for detecting leaks in food containers packaged under a protective atmosphere. Background Technology

[0002] Detecting leaks in sealed food containers packaged under a protective atmosphere typically involves the following steps: a) Apply mechanical stress to a sealed container using a compression technique to promote the escape of gas from the inside of the container to the outside in the event of a leak.

[0003] The mechanical stress is necessary because the pressure inside the food container is usually equal to atmospheric pressure.

[0004] b) Detect the concentration of one or more gases in the external environment near the container using one or more gas sensors.

[0005] The purpose of this step is to detect whether any gas is escaping from the container. This gas is part of the gas mixture that makes up the protective atmosphere inside the container, and its concentration inside the container is usually much higher than the normal concentration outside the container.

[0006] The area typically inspected is the entire outer surface of the container, where micro-leaks may be present.

[0007] Alternatively, a fume extraction hood can be used to detect the lower part of the container. The fume extraction hood extracts gas from the area near the lower part of the container and transports it to the detection area, where the concentration is detected by a gas sensor.

[0008] If the container is a pallet, the inspection is usually limited to the top of the pallet, and especially the joint area between the pallet and the film sealing the pallet.

[0009] c) Compare the measured gas concentration with the reference gas concentration of a leak-free container to determine whether the container under test is leaking.

[0010] While existing leak detection systems can perform the above functions, they are generally unable to apply appropriate pressure to the container, for example, to allow gas to escape from the container without damaging it.

[0011] For example, patent document US2022228944A1, under the applicant's name, discloses a leak detection system capable of performing the aforementioned function. This system applies mechanical stress to a container via a pair of rotatable rollers, each roller suspended on a corresponding floating arm hinged to its own hinge axis and connected to a corresponding cylinder. The cylinder applies pressure to the corresponding arm, which in turn applies pressure to the roller suspended thereon. Thus, the cylinder operates passively, and the roller moves vertically as it passes beneath the container. The assembly consisting of the arm, the corresponding cylinder, and the roller associated with the arm constitutes a third type of lever, where the vertical movement of each roller is a pivoting motion about the hinge axis of the corresponding floating arm. Specifically, the first roller pivots counterclockwise upwards when it encounters the container; the second roller pivots clockwise upwards when it encounters the container. This movement of the rollers often causes the container to jam, not only because of the vertical rotation of the rollers but also because of the upward clockwise pivoting of the second roller.

[0012] The purpose of this invention is to overcome the shortcomings of the prior art and provide a leak detection system that can squeeze the container in an appropriate manner to improve detection sensitivity, that is, to detect leaks smaller than those in the prior art.

[0013] Another object of the present invention is to provide a leak detection system that can be adapted to various containers.

[0014] These and other objectives can be achieved by the detection system defined in the appended claims. Summary of the Invention

[0015] The system for detecting leaks in sealed containers according to the present invention includes: A conveyor belt, which is configured to transport containers in the forward direction; A pressurization system is configured to apply a compressive mechanical load (extrusion) to a container by pressing the container against the conveyor belt. A suction and measurement system comprising a suction unit for suctioning gas from an area near a pressurized container and one or more sensors for detecting the concentration of one or more gases in the suctioned gas. A processing unit is configured to compare the gas concentration detected by the suction and measurement system with a reference gas concentration to determine whether there is a leak in the container under test.

[0016] Preferably, the leak detection system of the present invention is a system included in a container conveyor line, i.e., a so-called "online" detection system.

[0017] The pressurization system includes multiple rollers (two or more, preferably four rollers) associated with a moving component controlled by a control unit.

[0018] The moving components include height translation components configured to move the rollers vertically, each roller being independent of the others, so that the rollers, during their movement, conform to the shape of the container being measured, applying the maximum pressure the container can withstand without damaging it. These height translation components include, for example, a set of pistons, one piston corresponding to each roller.

[0019] According to the invention, the movement of the roller thus has a wave-like pattern: as the container passes through the detection system, the roller rises and falls, squeezing the container and adapting it to its shape. In this way, the container and the food inside are not damaged.

[0020] The rotation axis of the rollers of the pressurizing system (coinciding with their longitudinal axis) is parallel to the conveyor belt and perpendicular to the forward direction of the conveyor belt, and they are arranged one after another aligned along the forward direction of the conveyor belt.

[0021] Preferably, the moving component of the pressurization system is configured to drive the roller to rotate with the conveyor belt, and the circumferential speed of the roller is equal to the forward speed of the conveyor belt. The rotation of the roller at a circumferential speed equal to the forward speed of the conveyor belt prevents damage to the container, particularly to the sealing film of palletized containers.

[0022] The piston of the height translation member is operated, for example, in an active manner, and the initiation of its upward or downward movement of the roller is controlled by the passage of the container on the conveyor belt, which is detected by the phototube and encoder of the conveyor belt.

[0023] Alternatively, the piston of the height translation component can be operated passively, with a preloaded preset force.

[0024] Preferably, the multiple suction units of the suction and measurement system include at least one upper suction unit, at least one first lateral suction unit, and at least one second lateral suction unit.

[0025] The upper suction unit is arranged between two of the multiple rollers and is installed so that it can move in the height direction as a whole with one of the rollers, thereby minimizing the distance between the suction port of the upper suction unit and the test container passing near the upper suction unit.

[0026] The first and second lateral suction units are arranged laterally on opposite sides of the roller and fixed at a certain height and distance from the roller. The height and distance are selected according to the container to be tested, thereby minimizing the distance between the suction port of the lateral suction unit and the container to be tested passing near the lateral suction unit.

[0027] Optionally, the conveyor belt includes a first section and a second section arranged sequentially and spaced apart from each other. In this case, preferably, the suction and measurement system includes at least one lower suction unit disposed between the first and second sections of the conveyor belt, flush with the surface of the container placed on the conveyor belt, so that when the container to be tested moves from the first section to the second section of the conveyor belt, the suction port of the lower suction unit comes into contact with the container to be tested. Attached Figure Description

[0028] Referring to the accompanying drawings, these and other features and advantages of the invention will become apparent from the following description of preferred embodiments given by way of non-limiting example, wherein parts denoteed by the same or similar reference numerals have the same or similar functions and structures, and: Figure 1 A perspective view of the system for detecting container leaks according to the present invention is shown; Figure 2 It shows Figure 1 The side view shown is of a system used to detect container leaks. Figure 3 a-3g illustrates a schematic diagram of the different steps of the system for detecting container leaks in a first operating mode; and Figure 4 a-4d illustrates the different steps of the system for detecting container leaks in a second operating mode. Detailed Implementation

[0029] The following is combined Figure 1 and Figure 2 This describes an embodiment of the leak detection system 100 for sealed containers, especially food containers, according to the present invention.

[0030] The leak detection system 100 includes: A conveyor belt 10 is configured to transport containers, the conveyor belt comprising a first section 11 and a second section 12, which are arranged sequentially and spaced apart from each other. The pressurization system 20 is configured to apply a compressive mechanical load (extrusion) to the container by pressing it against the conveyor belt 10. A suction and measurement system 40 is configured to suction gas from an area near a pressurized container and measure the concentration of one or more gases in the suctioned gas. A processing unit (not shown) is configured to compare the gas concentration measured by the suction and measurement system 40 with a reference gas concentration to determine whether there is a leak in the container under test.

[0031] The pressurization system 20 includes four rollers, namely a first roller 21, a second roller 22, a third roller 23 and a fourth roller 24, which are associated with a motion member 25 controlled by a control unit (not shown).

[0032] The rotation axes of the rollers 21-24 (coinciding with the longitudinal axis of the rollers) are parallel to the conveyor belt 10 and perpendicular to the forward direction F of the conveyor belt 10, and are arranged one after another along the forward direction F.

[0033] The moving member 25 includes a rotating member, such as a belt (not shown), configured to drive rollers 21-24 to rotate with the conveyor belt (in the figure, the forward direction F of the conveyor belt 10 is from right to left, therefore the rollers 21-24 rotate clockwise). Furthermore, the rotating member is configured to drive the rollers 21-24 such that the rollers preferably have a circumferential speed (i.e., tangential speed) equal to the forward speed of the conveyor belt 10.

[0034] The motion component 25 further includes a height translation component configured to move the rollers 21-24 in a vertical direction, with each roller being independent of the others. Specifically, the height translation component includes a first piston 27 associated with the first roller 21 and a second piston (…) associated with the second roller 22. Figure 1 and Figure 2 (not shown in the image), the third piston 29 associated with the third roller 23, and the fourth piston associated with the fourth roller 24 (in the image). Figure 1 and Figure 2 (Not visible in the middle).

[0035] Due to the independent movement of the rollers 21-24, they can move vertically to conform to the shape of the container being tested, applying the maximum pressure the container can withstand without damaging it. Therefore, the movement of the four rollers 21-24 is wave-like: as the container passes through the detection system 10, the rollers 21-24 rise and fall, compressing and conforming to the container's shape. This prevents damage to the container and the food inside. Furthermore, the rollers 21-24 rotate at the same circumferential speed as the conveyor belt 10, preventing damage to the container, particularly the sealing film of tray-type containers.

[0036] Therefore, the pressurization system 20 can accommodate test containers of different sizes, shapes and hardnesses, such as small and large bags, trays, bags with trays, flat containers (such as so-called "piadine" packaging), trays sealed with plastic laminated paper film, plastic film or thermoformed film, etc.

[0037] According to the first embodiment, the pistons 27 and 29 of the height translation member operate in active mode, whereby the initiation of the upward or downward movement of the rollers 21-24 is controlled by the passage of the container 200 on the conveyor belt 10, which is detected by the phototube and encoder of the conveyor belt 10. Therefore, in this operating mode, the rollers 21-24 begin at a starting position where their height relative to the conveyor belt 10 is greater than the height of the container 200 under test, and descend as the container 200 advances on the conveyor belt 10 until the rollers reach a suitable height at which they can compress the container 200 with the maximum pressure it can withstand without damaging it. The height of the rollers at the starting position and the height of the rollers at the descending position are set according to the shape and size of the container under test. This operation of the pistons 27 and 29 is particularly advantageous for tray-type containers with a sealed top. In fact, in this configuration, the control unit of the pressurization system 20 is configured to drive the pistons 27 and 29 such that the rollers 21-24 act only on the top of the tray 200, and not on its front or rear, because the pressure exerted by the rollers on the front or rear could damage the tray (especially at the junction between the film and the tray). A schematic diagram of this operating mode of the leak detection system 10 is shown below. Figure 3 As shown in ag, the forward direction of container 200 is from right to left.

[0038] According to another embodiment, the pistons 27 and 29 of the height translation member operate in a passive mode, preloaded with a predetermined force. In this configuration, the rollers 21-24 start from a starting position where their height relative to the conveyor belt 10 is lower than the height of the container 300. Therefore, as the container 300 passes, each roller 21-24 (under the preload force of each roller) applies a certain pressure to the container and translates upward due to the resistance provided by the container 300, then returns downward under the push of the corresponding piston. The height of the rollers at the starting position is set according to the shape and size of the container to be tested. Furthermore, in this operating mode, the adjustment of the pistons is only used to determine the compressive force, while the timing of the rise / fall is determined by the interaction between the container 300 and the rollers 21-24. A schematic diagram of this operating mode of the leak detection system 10 is shown below. Figure 4 As shown in the diagram, the container 200 moves forward from right to left.

[0039] The suction and measurement system 40 includes multiple suction units, namely an upper suction unit 41, a first lateral suction unit 42, and a second lateral suction unit (in... Figure 1 and Figure 2 (Not visible in the middle) and the lower suction unit 43.

[0040] The upper suction unit 41 is disposed between the second roller 22 and the third roller 23, and preferably includes a plurality of downward-facing suction ports (not visible in the figure). The upper suction unit 41 is mounted so that it can move integrally with one of the rollers, for example, the second roller 22, in the height direction, thereby minimizing the distance (e.g., less than 5 mm) between its suction ports and the container being measured passing near the upper suction unit 41. The upper suction unit 41 may extend substantially the entire length of the roller. Alternatively, a plurality of upper suction units 41 may be provided, arranged sequentially along a direction parallel to the longitudinal axis of the roller, preferably arranged to substantially cover the entire length of the roller.

[0041] The first lateral suction unit 42 and the second lateral suction unit are arranged laterally relative to the rollers 21-24; specifically, the first lateral suction unit 42 is arranged on a first side of the rollers 21-24, and the second lateral suction unit is arranged on a second side of the rollers 21-24 opposite to the first side. When the system is viewed from the side, the two lateral suction units are located between the second roller 22 and the third roller 23. Each lateral suction unit has one or more suction ports (not visible in the figure) facing the rollers 21-24. The lateral suction units are fixedly mounted at a certain height and distance from the rollers, which is selected according to the container to be tested, in order to minimize the distance between the suction port of the lateral suction unit and the container to be tested passing near the lateral suction unit.

[0042] The lower suction unit 43 is disposed between the first section 11 and the second section 12 of the conveyor belt 10 and includes multiple upward-facing suction ports (not visible in the figure). Preferably, the lower suction unit 43 is flush with the surface 10a of the container placed on the conveyor belt 10, so that its suction ports come into contact with the container being tested as the container moves from the first section 11 to the second section 12 of the conveyor belt 10. The lower suction unit 43 preferably extends substantially over the entire length of the rollers 21-24. The presence of the lower suction unit 43 allows gas to be drawn from the area below the container being tested, thereby enabling the detection of leaks at the bottom of the container.

[0043] The suction and measurement system 40 also includes a gas sensor connected to the suction unit via a suitable conduit 45, allowing the suction gas to reach the sensor 46 to measure the concentration of one or more gases. Specifically, the sensor 46 measures the gas concentration in a gas mixture forming a protective atmosphere within the container, where the gas concentration is significantly higher than its concentration in the external environment. Typically, multiple sensors can be used to detect the concentration of a single gas; in fact, the more sensors used, the more accurate the gas concentration detection. Furthermore, a single sensor can be configured to detect the concentration of several different gases. Preferably, the sensor 46 is positioned below the conveyor belt 10.

Claims

1. A system (100) for detecting leaks in a sealed container, comprising: A conveyor belt (10) is configured to convey containers in the forward direction (F); A pressurization system (20) is configured to apply a compressive mechanical load to the container by pressing the container against the conveyor belt (10); A suction and measurement system (40) includes a suction unit (41, 42, 43) configured to suction gas from a region near a pressurized container and one or more sensors for measuring the concentration of one or more gases in the suction gas. The processing unit is configured to compare the gas concentration measured by the suction and measurement system (40) with a reference gas concentration to determine whether there is a leak in the container under test; The pressurization system (20) includes multiple rollers (21, 22, 23, 24) associated with a motion component (25) controlled by a control unit. The feature is that the motion member (25) includes a height translation member configured to move the rollers (21, 22, 23, 24) in the vertical direction, with each roller being independent of the others and the movement of the rollers conforming to the shape of the container being tested.

2. The system according to claim 1, characterized in that: The rotation axes of the rollers (21, 22, 23, 24) are parallel to the conveyor belt (10) and perpendicular to the forward direction (F) of the conveyor belt (10), and are arranged one after another along the forward direction (F).

3. The system according to claim 1 or 2, characterized in that: The multiple rollers include a first roller (21), a second roller (22), a third roller (23), and a fourth roller (24).

4. The system according to any one of the preceding claims, characterized in that: The motion component (25) is also configured to drive the rollers (21, 22, 23, 24) to rotate with the conveyor belt (10) and to make the rollers (21, 22, 23, 24) have a circumferential speed equal to the forward speed of the conveyor belt (10).

5. The system according to any one of the preceding claims, characterized in that: The height translation component includes pistons (27, 29) that operate in active mode, and the initiation of the upward or downward movement of the rollers (21, 22, 23, 24) caused by the container passing over the conveyor belt (10) is controlled by phototubes and encoders of the conveyor belt (10).

6. The system according to claim 5, characterized in that: The rollers (21, 22, 23, 24) start from an initial position where the height of the container (200) relative to the conveyor belt (10) is greater than the height of the container (200) to be tested, and descend as the container (200) moves forward on the conveyor belt (10) until the rollers reach a height suitable for applying the maximum pressure that the container (200) can withstand without damaging it.

7. The system according to claim 6, characterized in that: The control unit of the pressurization system (20) is configured to drive the pistons (27, 29) such that the rollers (21, 22, 23, 24) act only on the top of the container (200) and not on its front or rear.

8. The system according to any one of claims 1 to 4, characterized in that: The height translation component includes pistons (27, 29) that operate in passive mode and are preloaded with a predetermined force.

9. The system according to any one of the preceding claims, characterized in that: The suction unit of the suction and measurement system (40) includes at least one upper suction unit (41); wherein the at least one upper suction unit (41) is disposed between two rollers (22, 23) of the plurality of rollers (21, 22, 23, 24) and is mounted to move integrally with one of the rollers (22) in the height direction.

10. The system according to any one of the preceding claims, characterized in that: The suction unit of the suction and measurement system (40) includes at least one first lateral suction unit (42) and at least one second lateral suction unit; wherein the at least one first lateral suction unit (42) and the at least one second lateral suction unit are arranged laterally on both sides relative to the rollers (21, 22, 23, 24) and are fixedly installed at a certain height and distance from the rollers.

11. The system according to any one of the preceding claims, characterized in that: The conveyor belt (10) includes a first section (11) and a second section (12) that are arranged sequentially and spaced apart from each other.

12. The system according to claim 11, characterized in that: The suction unit of the suction and measurement system (40) further includes at least one lower suction unit (43), which is disposed between the first section (11) and the second section (12) of the conveyor belt (10) and is flush with the surface (10a) on which the container is placed on the conveyor belt (10).

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