Field of the Invention

This invention relates to a method and system of tamping a product in order that the product may be more readily packed into a container. In this context, "container" refers to a receptacle such as a tray having an upwardly facing opening. In particular, this invention relates to the tamping of a food product for packing into containers on a food packaging production line. Background to the Invention

Food packaging production lines typically comprise a system for placing food items into a container and a system for sealing the container, for example the automatic application of a film lid onto a tray. The packed and sealed container can then be labelled and distributed to the desired outlet, such as a supermarket.

Preferably, as much of the production line as possible is automatically actuated, in order to both save costs and increase speed and efficiency of the packing. This can cause problems when packing loose items of food product, such as salad. For example, when a portion of loose leaf salad is automatically deposited into a container, the salad will typically flow, forming a "dome" shape which extends above the height of the container. Attempting to seal such a packed container can lead to poor and uneven sealing, and during tray transfer increases spillage and wastage of the food.

In order to overcome this issue, it is known in the art to tamp, or "press down" on the salad in the container such that all of the salad is contained within the container and the container rim is clear for the sealing process to occur. Typically, a portion of salad will be measured out and deposited into a pre- formed rigid container. The salad, due to its loose nature and variable bulk densities, will settle such that it extends above the height of the container and therefore the container is unsuitable for packaging. The container will then move along a conveyor to a tamping station, where the salad will be tamped down such that it is all contained within the container.

However, due to the unstable nature of the initially deposited salad, leaves tend to fall out of the container or onto the rim of the container as it moves along the conveyor to the tamping station. Manual operators can re-pack the loose leaves in order that the sealing can take place, but of course the use of manual operators negates the advantages of an automatic system. They also reduce the efficiency of the packaging process.

There is therefore the requirement in the art for an improved method and system of packing and sealing loose items of food product into a container such that the container can be sealed, and which minimises spillage of the food product and overcomes the above problems.

FR-A-2846624 discloses a method and apparatus of filling containers with a food material involving allowing the food material to fall by gravity from a food dispenser down a guide tube aligned with a container opening, in order to prevent food from dropping onto the peripheral edges. With the guide still in place, the food is then pressed down by a pressure plate that passes through the guide tube. The containers are then sealed in a conventional manner. The guide is positioned such that its lower portion is level with the top of, or is contained within, the container. However, there are disadvantages to this apparatus. For example, the guide must correspond exactly to the container size otherwise food product will either fall over the sides of the container (if the guide is too large), or the container will be under-filled (if the guide is too small). Also, in retracting the guide tube and pressure plate from the container, food items may get snagged and drop outside the container. Further, the method requires the container to be present, and the product having flowed through the guide tube, before the tamping process can begin. Summary of the invention

In accordance with a first aspect of the present invention, we provide a method for filling a container with a food product, comprising; delivering a food product into a hopper; tamping, by means of a tamping block, said food product whilst it is in said hopper; locating a container having an upwardly facing opening beneath said hopper; and opening the hopper such that the tamped food product falls from the hopper into the container.

The invention therefore provides a new and inventive step of tamping a food product to reduce its volume whilst it is still in the hopper. Conventional apparatus which tamps the food product only after it has been delivered to the container carries the risk of spilling the food product either outside of the container or onto the rim of the container, which affects the sealing process. Therefore conventional apparatus typically requires a number of manual operators to remove any loose or spilled food items (such as salad leaves) before the sealing or lidding process. By initially tamping the food product in the hopper, the food product falls from the hopper into the container in pre- compressed and tamped state. This significantly reduces the amount of food spilled from the containers and thus does not require the use of manual operators, immediately reducing costs and increasing the efficiency of the system.

The containers are typically pre-formed, rigid plastic trays. Further, when packaging food items on a production line, the food product is typically stored for a short period of time in a hopper prior to it being delivered to the container. Tamping the food product whilst it is still in the hopper makes use of this "dead time", improving the efficiency and throughput of the production line. Additionally, the container does not need to be in place beneath the hopper until the hopper is opened. This means that the tamping can occur before the container is located beneath the hopper, in contrast to FR-A-2846624. This advantageously means that throughput of trays can be increased. Preferably, the hopper comprises a lower part comprising a door, and the step of releasing the food product from the hopper comprises opening said door such that the food product falls from the hopper into the container. The door may be slidable, or hinged. Typically, the door is driven by a pneumatic mechanism, although it may alternatively be operated by an electronically actuated motor.

The method may further comprise the subsequent step of lowering the tamping block towards the container through the open door of the hopper. This advantageously assists in keeping the pre-tamped food product in its tamped state as it falls towards and into the container.

Preferably, the step of lowering the tamping block towards the container is performed simultaneously with opening the hopper. This means that the food product is released from the hopper with downwards pressure applied by the tamping block. This advantageously causes the food product to fall to the container quickly, and further the lowering of the tamping block with the food product helps to guide the food into the container. It also helps to prevent the "expansion" of the food product subsequent to it being tamped in the hopper. The tamping block may be lowered a sufficient amount such that the food product is tamped, by the tamping block, whilst the food product is in the container. This advantageously provides a further tamping process of the food product. Preferably, such a second tamping process tamps the food product such that the food product is below the seal line of the container. When the food product is below the seal line, it tends not to "re-expand" above the seal line due to the friction of the container side walls.

Advantageously, the method may further comprise the step of lowering the hopper towards the container, wherein the step of lowering the hopper towards the container and the step of tamping said food product whilst it is in the hopper are performed simultaneously. The step of lowering the hopper towards the container aids in guiding the food product into the container once the hopper doors are opened. As this step is performed simultaneously with the tamping of the food product in the hopper, the hopper is lowered into position before the hopper doors are opened to release the food product.

The hopper may preferably be lowered such that its lower part is level and aligned with the top of the container. In this instance, the size of the hopper opening is substantially the same as that of the upper opening of the container, such that no food product is spilled over the side of the container. Alternatively, the hopper may be lowered to a position above and aligned with the top of the container. As a further alternative, the hopper opening may be smaller than the opening of the container, and the hopper is lowered into the container.

The method may further comprise the subsequent steps of tamping, by means of a second tamping block located separately to said first tamping block, the food product whilst said food product is in the container; lowering a shroud towards the container such that a lower part of the shroud is located below the opening of the container; and removing said second tamping block from the container whilst the shroud is still in the lowered position. This subsequent tamping advantageously ensures that any food product not initially tamped is sufficiently tamped below the level of the opening of the container in order to reduce spillage of food product and to ensure that the rim of the container is clear of food product for sealing.

The step of delivering the food product into a hopper may be performed at a first position, and the step of tamping the food product whilst it is in said hopper is performed at a second position, and wherein the first and second positions are spaced apart. When used in a food packaging production line, the first position may be at one location on the production line, and the second position at a different location on the production line. In such an instance, the hopper is moveable between the two locations, on a carriage for example. Having separate positions for delivering and tamping the food advantageously reduces the so-called "dwell time" of the system, thereby increasing the speed at which containers can be filled with food product, increasing throughput. This will be explained in more detail in the "detailed description" portion of the specification. Alternatively, the upper part of the hopper may be large enough to accommodate both the delivering of the food product and the tamping process at the same position. In such a case, the hopper has a substantially trapezoidal shape, with an angled side adapted to guide the delivered food product from the first position to the tamping position within the hopper.

In accordance with a second aspect of the present invention, we provide a tamping system for filling a container with a food product; the tamping system comprising; a hopper for holding a food product; a tamping block operable to tamp said food product in a first tamping process, whilst the food product is in the hopper; and wherein the hopper comprises a closable opening operable to release the food product from the hopper such that the food product falls from the hopper into a container having an upwardly facing opening.

Preferably, the tamping system of the second aspect of the invention may further comprise control apparatus adapted to actuate the tamping block in the first tamping process, and to open the closable opening; the control apparatus further adapted to actuate the tamping block before opening the closable opening.

The control apparatus actuating the tamping block before opening the closable opening ensures that the food product is tamped whilst it is in the hopper. The advantages of this "pre-tamping" of the food product in the hopper have been discussed above.

The closable opening may preferably comprise a door situated in a lower part of said hopper, the door operable to open such that food product falls from the hopper into the container. As explained above in relation to the first aspect of the present invention, the door may be electronically actuated, or driven by a pneumatic mechanism. Typically, the closable opening may comprise two hinged doors which abut one another in the closed position, providing a surface on which the food product can be tamped by the tamping block; and which hinge away from one another when the opened. The hinge is preferably located above the doors to provide a strong base on which to tamp the food product.

The tamping system may further comprise a first lowering apparatus operable to lower the tamping block towards the container through the open door of the hopper. This aids in keeping the food product in its compressed state after being tamped in the hopper, thus reducing spillage of food product from the containers.

The first lowering apparatus may be operable to lower the tamping block a sufficient amount such that the food product is tamped in a second tamping process, by the tamping block, whilst the food product is in the container. This advantageously provides a second tamping of the food product.

Preferably, the control apparatus is operable to simultaneously open the closable opening and activate the first lowering apparatus. This provides the benefit of the food product being released from the hopper under pressure from the tamping block. This means that the food product is guided to the container more quickly than if it simply fell from the hopper to the container under gravity. This feature of the invention also helps to prevent the food product expanding when moving from the hopper to the container after being tamped in the hopper.

Further, the tamping system of the present invention may comprise a second lowering apparatus operable to lower the hopper towards the container. Preferably, the control apparatus is adapted to simultaneously actuate the tamping block in the first tamping process, and the second lowering apparatus, such that the hopper is in the lowered position before the hopper is opened to release the food product. Lowering the hopper in this fashion provides a guide for the food product falling from the hopper to the container, thus preventing spillage of food product.

The second lowering apparatus may be operable to lower the hopper such that the lower part of the hopper is level and aligned with the opening of the container. Alternatively, the second lowering apparatus may be operable to lower the hopper such that the lower part of the hopper is above and aligned with the opening of the container, and in yet another alternative the second lowering apparatus may be operable to lower the hopper such that the lower part of the hopper is below the opening of the container.

The tamping block may preferably have a tamping surface in a plane substantially perpendicular to the direction of motion of the tamping block when it is being lowered, said surface having an area substantially identical to the inner cross sectional area of the hopper. For example, the tamping surface may be substantially rectangular, and corresponds to the rectangular cross sectional shape of the inner walls of the hopper. This feature advantageously means that when the tamping block is lowered through the hopper, any food product snagged or stuck on the inner walls of the hopper will be pushed down and tamped, thus reducing wastage of food product. Other shapes are envisaged however, for example the tamping block could have a circular tamping surface and the hopper could be substantially cylindrical.

Typically, the tamping system may further comprise a food dispenser adapted to dispense food product into the hopper. Preferably, the food dispenser is located at a first position and the first tamping block is located at a second position, wherein the first and second positions are spaced apart, and even more preferably, the hopper is moveable between the first and second positions. As will be discussed in more detail in the "detailed description" section of the specification, this arrangement advantageously allows the throughput of containers to be increased.

Alternatively, the hopper may have a trapezoidal shape with the lower part of the hopper and an upper part of the hopper being parallel; and further wherein the tamping block and food dispenser are aligned with an upper opening of the hopper. The trapezoidal nature of the hopper means that it comprises a sloped surface which guides food product dispensed from the food dispenser to the lower part of the hopper in order to be tamped within the hopper. This particular geometry of the hopper is particularly beneficial as the hopper does not have to move between separate food filling and tamping locations, thereby reducing the number of moving parts required.

However, other shapes of the hopper are envisaged, provided they have a surface adapted to transport the food product from the food dispenser to the tamping location.

The tamping system may further comprise a second tamping block located separately to the first tamping block and operable to tamp the food product whilst it is in the container, in a third tamping process; the tamping system further comprising a shroud operable to be lowered towards the container by a third lowering apparatus, the shroud being lowered such that a lower part of the shroud is located below the opening of the container, and wherein the second tamping block is removed from the container whilst the shroud is still in the lowered position. Such a second tamping block advantageously ensures that any food product not sufficiently tamped in the first and second tamping processes is tamped to a level below that of the opening of the container. This reduces spillage and wastage of food product, as well as ensuring that the rim of the container is clear for sealing.

In accordance with a third aspect of the present invention, there is provided a method for filling a plurality of containers with food product, the method comprising the steps of; (a) delivering, at a first position, food product into a hopper; (b) moving the hopper to a second position spaced from the first position; and either: (c) tamping, by means of a first tamping block, said food product whilst it is in said hopper at the second position; (d) locating a container, having an upwardly facing opening, beneath said hopper at the second position; (e) opening the hopper such that the food product falls from the hopper into the container; (f) removing the container from beneath the hopper at the second position; and (g) moving the hopper back to the first position; and repeating steps (a) to (g); or: (c1 ) locating a container, having an upwardly facing opening, beneath said hopper at the second position; (d1 ) opening the hopper such that the food product falls from the hopper into the container; (e1 ) tamping, by means of a tamping block in a first tamping process, the food product in the container at the second position; (f1 ) removing the container from beneath the hopper at the second position; and (g1 ) moving the hopper back to the first position; and repeating the steps (a) to (g1 ).

Any of the features of the first and second aspects of the invention may be incorporated into the third aspect of the invention

The time required to fill a container with food product and tamp said food product can be split into a so-called "dwell time" and an "index time". The "dwell time" is the time during which the food product in the container is being tamped at the second position. Preferably the container is stationary for this process. The "index time" is the time taken between tamping processes. Typically, this is the time taken for an empty container to move from its position when a previous container is being filled, to when it is located beneath the hopper at the second position. In the manner of this third aspect of the invention, the inventors have reduced the "dwell time" without compromising on the "index time" and have thus increased the throughput of containers filled with tamped food product. Preferably, the container may be located beneath the hopper at the second position not earlier than the hopper is moved to the second position. This includes the container being located beneath the hopper at the same time as the hopper arrives at the second position. This advantageously means that the "index time" of the system is not limited by the time taken to move the hopper. Alternatively however, the container may be located beneath the hopper at the second position earlier than the hopper is moved to the second position. This aspect of the invention is explained in more detail in the "detailed description" section of the specification. In the third aspect of the invention, the tamping may occur in the hopper itself (so-called "pre-tamping"), or within the container. Alternatively, the food product may be pre-tamped in the hopper in a first tamping process, and subsequently tamped in the container in a second tamping process The plurality of containers may preferably be located on a moveable conveyor and spaced at a fixed pitch. As an example, containers are typically spaced apart at a fixed pitch on a conveyor, such as 14 inches. Therefore, while one container is being filled with food product and tamped, the next container to be processed is 14 inches away on the conveyor at a "holding" position. When the first container has been filled with tamped food product, the hopper moves from the second position to the first position and back to the second position having been re-filled with food product in a shorter or equal amount of time than it takes the next container to move the 14 inches from its "holding position" to being located beneath the hopper at the second position (the so-called "index time"). Alternatively, the hopper moves from the second position to the first position and back to the second position having been re-filled with food in a greater amount of time than it takes the second container to move the 14 inches from its "holding" position to being located beneath the hopper at the second location.

In accordance with a fourth aspect of the invention, there is provided a tamping system for filling a plurality of containers with food product, the tamping system comprising; a hopper for holding a food product and comprising a closable opening; a food dispenser located at a first position operable in use to dispense food into the hopper at the first position; hopper transport apparatus operable in use to transport the hopper between the first position and a second position spaced from said first position; container transport apparatus operable in use to transport a container; a tamping block located at the second position; and control apparatus operable to: (a) actuate the food dispenser to deliver a food product into the hopper at the first position; (b) actuate the hopper transport apparatus to move the hopper containing the food product to the second position; and either: (c) lower the tamping block so as to tamp the food product whilst it is in said hopper at the second position; (d) actuate the container transport apparatus to locate a container, having an upwardly facing opening, beneath the hopper at the second position; (e) open the closable opening to release the food product from the hopper into the container; (f) actuate the container transport apparatus to remove the container from beneath the hopper at the second position; and (g) actuate the hopper transport apparatus to move the hopper back to the first position; and wherein the control apparatus is further adapted to repeat the steps (a) to (g); or: (c1 ) actuate the container transport apparatus to locate a container, having an upwardly facing opening, beneath the hopper at the second position; (d1 ) open the closable opening to release the food product from the hopper into the container, and to lower the tamping block into the container to tamp the food product in the container; (e1 ) actuate the container transport apparatus to remove the container from beneath the hopper at the second position; and (f1 ) actuate the hopper transport apparatus to move the hopper back to the first position; and wherein the control apparatus is further adapted to repeat the steps (a) to (f1 ).

Any of the features of the first, second and third aspects of the invention may be incorporated into the fourth aspect of the invention.

As briefly described above and as will be described in more detail later, the system of the fourth aspect of the invention advantageously increases the throughput of containers filled with tamped food product. In the fourth aspect of the invention, the tamping may occur within the hopper (so-called "pre-tamping"), or within the container. Alternatively, the food product may be pre-tamped in the hopper in a first tamping process, and subsequently tamped in the container in a second tamping process The control apparatus may further be adapted to control the container transport apparatus and the hopper transport apparatus such that the container is located beneath the hopper at the second position not earlier than the hopper is moved to the second position. Typically, the container transport apparatus is a movable conveyor on which the containers are located and spaced apart at a fixed pitch. Brief description of the drawings

The present invention will now be compared and contrasted with the prior art through reference to the following drawings, in which:

Figure 1 is a perspective view of a first embodiment of the present invention; Figure 2 is a perspective view of a third embodiment of the present invention at a time instant T1 ;

Figure 3 is a perspective view of the third embodiment of the present invention at a time instant T2 later than T1 ;

Figure 4 is a perspective view of the third embodiment of the present invention at a time instant T3 later than T2;

Figure 5 is a perspective view of the third embodiment of the present invention at a time instant T4 later than T3;

Figure 6 is a perspective view of the third embodiment of the present invention at a time instant T5 later than T4;

Figure 7a is a perspective view of a tamping apparatus according to a second embodiment of the invention, in a first position;

Figure 7b is a perspective view of a tamping apparatus according to a second embodiment of the invention, in a second position;

Figure 8 is a perspective view of a dual lane system food packaging system comprising one embodiment of the present invention;

Figure 9 is a flow chart summarisng the steps of the first and second embodiments of the invention;

Figure 10 is a flow chart summarising the steps of the third embodiment of the invention, and;

Figure 11 is a flow chart summarising the steps of a fourth embodiment of the invention.

Detailed description of the drawings

In a first embodiment of the invention, a tamping system 200 is provided, as seen in Figure 1. Tamping system 200 comprises a container conveyor (not shown) on which there is a plurality of containers spaced at a predetermined pitch. The conveyor is typically a fixed-pitch indexing conveyor comprising a plurality of indexing flights spaced at fixed pitch. Two such containers are labelled at 1 a and 1 b. Here, the containers are moving in the direction of arrow

Tamping system 200 further comprises a trapezoidal hopper 35 comprising an upper part 36, a lower part 37 and an angled side 38. The lower part 37 comprises a pair of doors 6a, 6b hinged at 21. A tamping block 7 and food product dispenser 30 are provided at the upper part 36 of the hopper 35.

Doors 31a, 31 b on food dispenser 30 are opened and food product 20 is released from the food dispenser 30 into the hopper 35 onto the angled side 38. The food product 20 is guided down the angled side 38 under gravity until it comes to rest on the closed doors 6a, 6b of the lower part 37 of hopper 35. In the closed position, the doors 6a, 6b abut one another so as to form a base to the hopper.

Tamping block 7 is then lowered by a linear actuator (not shown) such that it compresses the food product 20 between the tamping block 7 and the closed doors 6a, 6b in a first tamping process. The area of the tamping block 7 perpendicular to its motion is substantially the same as that of the lower part 37 of the hopper such that all of the food product is tamped. The doors 6a, 6b are "scraper style" doors hung with the hinge 21 above the doors themselves. This means that the doors provide a solid base on which to carry out the first tamping process. At the same time as the food product 20 is being tamped in the first tamping process, hopper 35 is lowered by a mechanism (not shown) such that the lower part 37 is at the same height as the top of container 1 a. The cross-sectional area of the lower part 37 is smaller than the area of the open part of the top of the container, such that all of the food product falls from the hopper 35 into the container. Typically, when the lower part 37 is in the lowered position, there is a 15mm gap between the lower part 37 and the container rim on all sides of the container. Alternatively, the cross sectional areas of the lower part and the top of the container may be identical, or the cross sectional areas of the lower part may be larger than the top of the container.

In use container 1 a is moved along the container conveyor until it is located beneath the lower part 37 of hopper 35. When the container 1 a is in position, the container conveyor is stopped. When the hopper 35 is in the lowered position, pneumatic mechanism 1 1 is actuated and causes the doors 6a, 6b swing open about hinge 21 , allowing the food product 20 to fall from the hopper 35 into the container 1 a. The container does not need to be in position until the doors 6a, 6b are opened. The lowering of the hopper 35 towards the container acts as a guide for the food product 20 falling from the hopper 35 to the container 1 a.

The doors 6a, 6b are opened as the food product 20 is being compressed by tamping block 7 in the first tamping process, such that the food product 20 is released under pressure from the tamping block 7. The tamping block 7 continues to be lowered through the hopper 35 and into the container 1 a so as to further compress the food product 20 in a second tamping process.

Once the second tamping process is complete, the tamping block 7 is raised back to its original position, the doors 6a, 6b are closed and the hopper 35 returns to its original position. During this time the food dispenser 30 is re-filled with food product. The next container 1 b to be filled is then transported along container conveyor until it is located beneath the hopper 35. The process then repeats.

Meanwhile, the filled container 1a (an example of a filled container is shown at 25) is transported along the container conveyor to the next apparatus in the food production line.

Although the tamping system 200 has been described in relation to a single hopper 35, a two-hopper system where two containers are filled with tamped product simultaneously is envisaged. Similarly, systems comprising three or more hoppers are envisaged. In a second embodiment, the next apparatus in the food production line is a secondary tamping system 300 operable to perform a third tamping process. Such a secondary tamping system 300 is shown in Figures 7a and 7b. The secondary tamping apparatus comprises tamping blocks 301 a, 301 b and shrouds 302a, 302b. The shrouds are connected by rigid cross member 306 such that they move in synchrony. Figures 7a and 7b show a secondary tamping apparatus comprising two tamping blocks; however the following description will refer to a single block for clarity purposes. The filled container 1 a will move from the tamping system 200 and stop on the conveyor beneath the tamping block 301 a. The tamping block 1a is connected by rigid member 308 to pneumatic mechanism 310. In use, hydraulic mechanism 310 lowers tamping block 301 a into the filled container 1 a to tamp the food product in a third tamping process. Straight after the third tamping process has occurred, and with the tamping block still located in the container, shroud 302a is lowered by pneumatic system 305. As seen in Figure 7b, the shroud is smaller than the container such that it is lowered into the container itself. The tamping block 301 a is then raised with the shroud still in the container in order to prevent spillage of food product when the tamping block is raised. The shroud is then raised and the container moves along the conveyor to the next apparatus in the food production line, typically a container sealer. As will be appreciated by the skilled person, the mechanism 310 may be driven by means other than pneumatics, such as hydraulics.

Figures 7a and 7b show a dual secondary tamping system 300 which two side- by-side tamping blocks. However, a secondary tamping system with one tamping block, as well as a system with three of more blocks is envisaged. It should also be pointed out that figures 7a and 7b show the secondary tamping system 300 in use in a "dual lane" container sealing line, with two lines of containers running adjacent each other. However, the secondary tamping system 300 is also suitable for use in a single lane container sealing line, or in a container sealing line comprising three or more lanes. The tamping system 200 of the first embodiment of the invention therefore advantageously "pre-tamps" the salad in the hopper before releasing it into the containers. This means that less food product (such as salad) is spilled out of and onto the rims of the containers, thereby reducing wastage and increasing the reliability of the subsequent container sealing.

Figure 9 is a flow chart summarising the steps outlined above. At step 901 food product is delivered to the hopper from food dispenser. At step 902 the food product which has been delivered to the hopper is tamped by tamping block whilst it is in the hopper. At step 903 a container is located beneath the hopper such that the tamped food product is able to fall from the hopper into the container. Optionally, as step 904, the hopper may be lowered towards the container such that the food product does not have to fall so far from the hopper to the container. At step 905, the hopper doors open and the pre- tamped food product falls into the container.

The method may further comprise the optional steps 906, 907 and 908. At step 906, the food product is tamped by the first tamping block whilst it is in the container, with the container remaining located beneath the hopper. Preferably the tamping block continues to be lowered through the hopper as the doors are opened such that the pre-tamped food product falls into the container under force from the tamping block and is subsequently tamped within the container. At step 907, the container is positioned such that it is spaced from the hopper and the first tamping block. A shroud is lowered such that a lower part of the shroud is located below the opening of the container. Then, at step 908, the food product within the container is tamped by a second tamping block to advantageously further tamp the food product.

The description of the first and second embodiments with respect to Figures 1 , 7a and 7b includes the optional steps 904, 906, 907 and 908 of the flow chart in Figure 9. Figure 2 shows a schematic view of a tamping system 100 according to a third embodiment of the invention at time instant T1. A plurality of unfilled containers 1 are arranged on a container conveyor (not shown), with the conveyor configured to move the containers from left to right in the configuration of Figure 1 (see arrow "A"). The typical pitch between containers is 14 inches.

A filling position shown generally at 101 comprises two hoppers 2a, 2b. A hopper comprises a hopper main body 3, an upper part 4 and a lower part 5. The lower part 5 comprises a set of hinged "scraper style" doors 6a and 6b similar to those seen in Figure 1. Figure 2 shows an example of a "dual" tamping system 100 comprising two hoppers 2a, 2b, but it will be appreciated that the tamping system 100 may comprise a single hopper, or more than two hoppers.

At the filling position 101 , food product 20 is deposited into the hopper from food dispenser (not shown) as shown by the arrows in Figure 2. The upper part 4 of the hopper is flared so as to allow easy guidance of the food product into the hopper main body 3. The main body 3 has a rectangular cross section, although other geometries are envisaged, such as the main body 3 being a cylinder. At this time instant T1 , doors 6a and 6b abut one another such that the lower part 5 of the hopper is closed and forms a base to hopper 2. The food product is therefore contained within the hopper main body 3.

Figure 3 shows the tamping system at time instant T2 later than T1. As can be seen in the figure, the containers 1 a, 1 b have moved along the conveyor in the direction of arrow "A". Additionally, the hoppers 2a, 2b have moved along carriage 10 to the tamping position shown generally at 102. In this embodiment, the conveyor and carriage 10 are linear; however other geometries are envisaged to fit the particular packaging line, such as a curved conveyor and carriage. The hoppers 2a, 2b are connected together via rigid hopper cross beam 12a and moveably mounted to carriage 10 through mounting 12. Hopper cross beam 12a is connected to mounting 12 through vertical slide 12b (see Figure 3). The hoppers are mounted to the carriage in a conventional manner (such as using a quick release clamp) which will not be discussed further herein. The rigid hopper cross beam 12a keeps the hoppers 2a, 2b spaced apart at a fixed pitch.

The tamping position 102 comprises two tamping blocks 7a, 7b, although it will be appreciated that the tamping system may comprise a single tamping block or more than two tamping blocks. Ideally, the number of tamping blocks 7 corresponds to the number of hoppers 2. In the present embodiment the two tamping blocks 7a, 7b are mounted via respective rigid tamping rods 8a, 8b to rigid tamping cross beam 9. The tamping cross beam keeps the tamping blocks 7a, 7b spaced apart at a fixed pitch. The pitch of the tamping blocks 7 is equal to the pitch of the hoppers 2a, 2b such that the tamping blocks are coaxial with the hoppers. The tamping cross beam 9 is mounted to linear actuator 15.

As can be seen in Figure 3, at time instant T2, the tamping blocks 7a, 7b are aligned with and vertically spaced from the hopper upper parts 4 such that hoppers 2a, 2b can move from filling position 101 to tamping position 102 along the carriage 10 uninterrupted.

Figure 4 shows the tamping system 100 at time instant T3 later than T2. Here the containers 1a, 1 b have moved along the conveyor such that they are situated beneath their respective hoppers 2a, 2b. The pitch between containers 1 a, 1 b is the same as the pitch between the hoppers 2a, 2b and the tamping blocks 7a, 7b. The containers 1 a, 1 b are kept at the correct pitch through the use of a fixed-pitch indexing conveyor with indexing flights. However, other conveyors may be used such as a variable-pitch indexing conveyor, or a conveyor with no indexing flights but where the containers are positioned on the conveyor at the necessary pitch (for example by gripper arms).

The following description will refer to a single container 1 a and its corresponding hopper 2a for clarity purposes.

Tamping block 7a is lowered through the upper part 4 of hopper 2a in the direction of arrow B by linear actuator 15a (see Figure 4). The tamping block 7a comes into contact with food product 20, compressing it between the tamping block 7a and the closed hopper doors 6a, 6b in a first tamping process. The scraper style doors are hung with hinges above the doors themselves, therefore providing a strong solid base on which the first tamping process can occur. The first tamping process advantageously reduces the volume of the food product. The position of the tamping block 7a in the first tamping position is shown at 7a'. Similarly, the position of lowered tamping block 7b is shown at 7b'

The area of tamping block 7a perpendicular to the direction of its motion is substantially identical to the cross sectional area of hopper main body 3a, such that when the tamping block 7a is lowered, all of the food product 20 in the hopper is compressed. This also allows any food product that has snagged on the sides of the hopper main body (such as lettuce leaves for example) to also be tamped by tamping block 7a.

As the tamping block 7a is lowered through the hopper main body 3a in the first tamping process, hopper cross bar 12a is lowered via vertical slide 12b (see Figure 5) such that hopper 2a is lowered towards container 1a. Preferably this is done simultaneously to the tamping block 7a compressing the food product 20 against the closed hopper doors 6a, 6b in the first tamping process. In this embodiment, the hopper 2a is lowered such that the lower part 5 of the hopper is level with the top of the container. The perimeter of the lower part 5 of hopper 2a substantially corresponds to the rim of the container. The cross-sectional area of the lower part 5 is smaller than the area of the open part of the top of the container, such that all of the food product falls from the hopper 2a into the container. Typically, when the lower part 5 is in the lowered position, there is a 15mm gap between the lower part 5 and the container rim on all sides of the container. Alternatively, the cross sectional areas of the lower part and the top of the container may be identical.

Figure 5 shows the tamping system 100 at time instant T4 later than T3. When the hopper 2a has been lowered as described above, the hopper doors 6a, 6b open (as seen in Figure 5) such that the food product 20 falls in the direction of arrow C from hopper 2a into container 1a, which has been positioned on the conveyor beneath the hopper 2a. When the container 1a is in position beneath the hopper 2a, the conveyor is stopped such that the container 1 a is stationary. The doors 6a, 6b are hinged at hinge 21 and are driven by pneumatic system 1 1 such that they open outwards away from container 1 a. However, other means for releasing the food product from the hopper are envisaged, such as a single sliding door. It is to be appreciated that the container 1 a only has to be in position beneath the hopper when the doors 6a, 6b are opened. For example, the container 1 a may still be moving along the conveyor when the first tamping process is taking place.

Tamping block 7a continues to be lowered via linear actuator 15 through the hopper main body 3a and into the container, as seen in Figure 6. This advantageously tamps the food product within the container 1 a itself, in a second tamping process. The hopper 2a is lowered towards container 1 a and the doors 6a, 6b are opened (as described above) whilst the tamping block is still compressing the food product against the doors 6a, 6b in the first tamping process. This means that when the doors 6a, 6b are opened, the food product is released under pressure from the tamping block 7a. This not only increases the speed at which the food product enters the container 1 a, it also aids in preventing the food product from losing its compressed shape.

Lowering the hopper 2a towards the container 1 a advantageously provides a guide surface for the food product as it is released into the container 1 a prior to the second tamping process. As described hereinabove, the hopper 2a is lowered such that the lower part 5 of the hopper 2a cooperates with the rim of the container. This prevents any spillage of food product during the second tamping process. However, in other embodiments, the hopper 2a may be lowered such that the lower part of the hopper is above the container. In yet another embodiment, the lower part of the hopper has a smaller area than the container, and the hopper is lowered into the container in order to protect even further against spillage of food product. Once the second tamping process has taken place, the tamping block 7a is retracted from the container 1 a and raised back up through the hopper main body 3a. The doors 6a, 6b close and the hopper 2a is raised, via vertical slide 12, back to its original position. During this time the food dispenser is re-filled with food product. The conveyor is then started again, transporting filled containers 1 a, 1 b to the next part of the production line. This is typically a container sealing apparatus, although it could also be the secondary tamping system 300 as described above in relation to figures 7a and 7b. Examples of filled containers are seen at 25 in Figure 6.

The inventors have realised a further technical advantage provided by the apparatus of the third embodiment, as will now be described. The time taken to fill a container can be split into a "dwell time" and an "index time". The "dwell time" is the time that the container is stationary beneath the hoppers whilst the tamping process occurs, and the "index time" is the time taken for the container to move from one index position to the next. It is difficult to reduce the "index time" because the containers are typically made of plastic and are very light, therefore making it difficult to move them along the conveyor quickly. The inventors have discovered that the "dwell time" is reduced through the use of hoppers 2a, 2b that are smaller than those used in the first embodiment. Specifically, the smaller height of the hoppers 2a, 2b means that the distance travelled by the tamping blocks 7a, 7b in the first and second tamping processes is reduced, thereby reducing the "dwell time" and increasing the throughput of containers.

The reason that the hoppers 2a, 2b can be made smaller in the third embodiment is due to the fact that they move between separate filling and tamping positions 101 , 102. With the trapezoidal-shaped hoppers of the first embodiment, there was the requirement to have the tamping block and food dispenser operating on the same hopper. However, the sloped side of a trapezoidal-shaped hopper (shown at 38 in the first embodiment) requires a steep angle with respect to the horizontal (typically 70°) in order to ensure that the food product dispensed from the food dispenser is able to fall down the sloped side and onto the doors 6a, 6b. This is particularly the case with salad which has a tendency to stick to the walls of the hopper. Consequently, the tamping block is required to move a long distance when used with a trapezoidal hopper, typically around 600-700mm, giving rise to a long "dwell time".

The separate filling and tamping positions of the third embodiment means that the hoppers can be made smaller, reducing the travel length of the tamping blocks, and therefore reducing the "dwell time".

In the view of Figure 6, containers 1c and 1d are the next containers to be filled with food product and are in their "holding" positions on the conveyor. Hoppers 2a and 2b are transported along carriage 10 back to filling position 101 where they are filled with food product from food dispenser as described in relation to Figure 2. They are then transported back along carriage 10 to the tamping position as previously explained in relation to Figure 3. The conveyor speeds and carriage speeds are such that in the time the hoppers 2a, 2b have been refilled with food product at the filling position 101 and returned to the tamping position 102, the containers 1 c and 1 d will have moved to the tamping position 102. (As explained above, the time taken for the containers 1 c and 1d to move from their "holding" positions in Figure 6 to the tamping position 102 is the "index time".) In other words, the hoppers 2a, 2b are transported to filling position 101 , filled with food and then returned to the tamping position 102 in a time equal to or less than the index time of the system. This advantageously means that in the third embodiment, the dwell time is reduced whilst the index time remains the same, thereby increasing throughput. However, it is also possible that the hoppers 2a, 2b are transported to filling position 101 , filled with food and then returned to the tamping position 102 in a time longer than the index time. Figure 10 is a flow chart summarising the steps of the third embodiment outlined above. At step 1001 , food product is delivered into a hopper located at a filling position. At step 1002 the hopper is moved to a tamping position, typically along a carriage. The hopper is now located at the tamping position, and contains food product. At step 1003, the food product is then tamped within the hopper using a first tamping block in order to "pre-tamp" the food product.

At step 1004, a container to be filled with the food product is located beneath the hopper at the tamping position, such that food product is able to fall from the hopper and into the container. At step 1006, the hopper doors are opened such that the pre-tamped food product falls into the container. Optionally, before the hopper doors are opened, the hopper may be lowered towards the container (step 1005) such that the food product falls a shorter distance than would otherwise be the case.

As a further optional step, the food product can also be tamped within the container (step 1007). This is done using the first tamping block which is lowered into the container after the hopper doors are opened in order to tamp the product in the container.

At step 1008, the container, now filled with tamped food product, is removed from beneath the hopper at the tamping position. Typically, the container will be transported along a conveyor to the next apparatus on the production line, such as a tray sealer. The hopper is moved back to the filling position along the carriage (step 1009) and the process then loops back to step 1001.

The above description of the third embodiment in relation to Figures 2 to 6 includes the optional steps 1005 and 1007.

As described above, the container is located beneath the hopper at the tamping position not earlier than the hopper is moved to the tamping position (more specifically, when the hopper doors are opened), which advantageously increases throughput.

Figure 11 is a flow chart summarising the steps of a fourth embodiment of the invention. At step 1 101 , food product is delivered into a hopper located at a filling position. At step 1 102 the hopper is moved to a tamping position, typically along a carriage. The hopper is now located at the tamping position, and contains food product. At step 1 103 a container is located beneath the hopper at the tamping position. At step 1 105, the hopper doors are opened such that food product falls from the hopper into the container. Optionally, before the hopper doors are opened, the hopper may be lowered towards the container (step 1 104) such that the food product falls a shorter distance than would otherwise be the case. At step 1 106, the food product, which is now located in the container, is tamped using a first tamping block. The first tamping block is typically lowered through the open base of the hopper and into the container so as to tamp the food product.

At step 1 107, the container, now filled with tamped food product, is removed from beneath the hopper at the tamping position. Typically, the container will be transported along a conveyor to the next apparatus on the production line, such as a tray sealer. At step 1108 the hopper is moved back to the filling position along the carriage and the process then loops back to step 1001.

As described above, the container is located beneath the hopper at the tamping position not earlier than the hopper is moved to the tamping position (more specifically, when the hopper doors are opened), which advantageously increases throughput.

A major advantage of both tamping systems 100 and 200 is their automatic nature. The automatic nature of the tamping system is provided by a timing control system (not shown). Once the input variables of the system are known, such as the pitch of the containers on the conveyor and the speed of the container conveyor, it is possible to automatically set the system 100, 200 such that the containers stop at the correct time and in the correct place, the first tamping process occurs at the correct time, the hopper doors open at the correct time and so on. Alternatively, sensors can be used to determine when a container is located underneath the hopper, at which instance the conveyor is stopped and the first and second tamping processes are automatically carried out.

The above embodiments have been described in relation to a single container conveyor (single lane production line). However, the tamping system of the present invention may also be used in a dual lane production line 400 with two production lines 401 , 402, as seen in Figure 8, or a production line with three or more lanes. In the present invention, up to 100 containers per minute can be filled with tamped food product on a dual lane production line (50 containers per minute per lane).

The features seen in the above described embodiments are not limited to that particular embodiment, and may be used in other embodiments. The above embodiments have been described predominantly in relation to food products, for example loose leaf salad, protein, vegetables and pasta. However, the invention is not limited to food products; for example it could be used to tamp other items such as clay, sand or dirt.