Technical Field

The present invention relates to the technical field of automated storage and retrieval systems.

In particular, the present invention relates to an automated storage and retrieval system comprising a container handling station.

Background and prior art

Fig. 1 discloses a framework structure 1 of a typical prior art automated storage and retrieval system and fig. 2 discloses a container-handling vehicle of such a system.

The framework structure 1 comprises a plurality of upright members 2 and a plurality of horizontal members 3, which are supported by the upright members 2. The members 2, 3 may typically be made of metal, e.g. extruded aluminium profiles.

The framework structure 1 defines a storage grid 4 comprising storage columns 5 arranged in rows, in which storage columns 5 storage containers 6, also known as containers, are stacked one on top of another to form stacks 7. Each storage container 6 may typically hold a plurality of product items (not shown), and the product items within a storage container 6 may be identical, or may be of different product types depending on the application. The framework structure 1 guards against horizontal movement of the stacks 7 of storage containers 6, and guides vertical movement of the containers 6, but does normally not otherwise support the storage containers 6 when stacked.

The horizontal members 3 comprise a rail system 8 arranged in a grid pattern across the top of the storage columns 5, on which rail system 8 a plurality of container- handling vehicles 9 are operated to raise storage containers 6 from and lower storage containers 6 into the storage columns 5, and also to transport the storage containers 6 above the storage columns 5. The rail system 8 comprises a first set of parallel rails 10 arranged to guide movement of the container -handling vehicles 9 in a first direction X across the top of the frame structure 1, and a second set of parallel rails 1 1 arranged perpendicular to the first set of rails 10 to guide movement of the container-handling vehicles 9 in a second direction Y, which is perpendicular to the first direction X, see fig. 3. In this way, the rail system 8 defines an upper end of grid columns 12 above which the container -handling vehicles 9 can move laterally above the storage columns 5, i.e. in a plane, which is parallel to the horizontal X-Y plane.

Each container-handling vehicle 9 comprises a vehicle body 13 and first and second sets of wheels 14, 15 which enable the lateral movement of the container-handling vehicle 9, i.e. the movement in the X and Y directions. In Fig. 2 two wheels in each set are visible. The first set of wheels 14 is arranged to engage with two adjacent rails of the first set 10 of rails, and the second set of wheels 15 arranged to engage with two adjacent rails of the second set 11 of rails. Each set of wheels 14, 15 can be lifted and lowered, so that the first set of wheels 14 and/or the second set of wheels 15 can be engaged with the respective set of rails 10, 1 1 at any one time.

Each container-handling vehicle 9 also comprises a lifting device (not shown in Fig. 1) for vertical transportation of storage containers 6, e.g. raising a storage container 6 from and lowering a storage container 6 into a storage column 5. The lifting device comprises a gripping device (not shown) which is adapted to engage a storage container 6, which gripping device can be lowered from the vehicle body 13 so that the position of the gripping device with respect to the vehicle body 13 can be adjusted in a third direction Z, which is orthogonal the first direction X and the second direction Y.

Conventionally, and for the purpose of this application, Z=l identifies the uppermost layer of the grid 4, i.e. the layer immediately below the rail system 8, Z=2 the second layer below the rail system 8, Z=3 the third layer etc. In the embodiment disclosed in Fig. 1, Z=8 identifies the lowermost, bottom layer of the grid 4. Consequently, as an example and using the Cartesian coordinate system X, Y, Z indicated in Fig. 1 , the storage container identified as 7' in Fig. 1 can be said to occupy grid location or cell X=10, Y=2, Z=3. The container-handling vehicles 9 can be said to travel in layer Z=0 and each grid column can be identified by its X and Y coordinates.

Each container-handling vehicle 9 comprises a storage compartment or space for receiving and stowing a storage container 6 when transporting the storage container 6 across the grid 4. The storage space may comprise a cavity arranged centrally within the vehicle body 13, e.g. as is described in WO2014/090684A1 , the contents of which are incorporated herein by reference.

Alternatively, the container-handling vehicles may have a cantilever construction, as is described in N0317366, the contents of which are also incorporated herein by reference.

The container-handling vehicles 9 may have a footprint, i.e. an extension in the X and Y directions, which is generally equal to the lateral or horizontal extension of a grid column 12, i.e. the extension of a grid column 12 in the X and Y directions, e.g. as is described in WO2015/193278A1 , the contents of which are incorporated herein by reference. Alternatively, the container-handling vehicles 9 may have a footprint which is larger than the lateral extension of a grid column 12, e.g. as is disclosed in WO2014/090684A1. The rail system 8 may be a single rail system, as is shown in Fig. 3. Alternatively, the rail system 8 may be a double rail system, as is shown in Fig. 4, thus allowing a container-handling vehicle 9 having a footprint 44 generally corresponding to the lateral extension of a grid column 12 to travel along a row of grid columns in either an X or Y direction even if another container -handling vehicle 9 is positioned above a grid column neighbouring that row.

In a storage grid, a majority of the grid columns 12 are storage columns 5, i.e. grid columns where storage containers are stored in stacks. However, a grid normally has at least one grid column which is used not for storing storage containers, but which comprises a location where the container-handling vehicles can drop off and/or pick up storage containers so that they can be transported to an access station where the storage containers can be accessed from outside of the grid or transferred out of or into the grid, i.e. a container handling station. Within the art, such a location is normally referred to as a "port" and the grid column in which the port is located may be referred to as a port column.

The grid 4 in Fig. 1 comprises two port columns 19 and 20. The first port column 19 may for example be a dedicated drop -off port column where the container-handling vehicles 9 can drop off storage containers to be transported to an access or a transfer station (not shown), and the second port 20 column may be a dedicated pick-up port column where the container-handling vehicles 9 can pick up storage containers that have been transported to the grid 4 from an access or a transfer station.

The access station may typically be a picking or a stocking station where product items are removed from or positioned into the storage containers. In a picking or a stocking station, the storage containers are normally never removed from the automated storage and retrieval system, but are returned back into the grid once accessed. A port can also be used for transferring storage containers out of or into the grid, e.g. for transferring storage containers to another storage facility (e.g. to another grid or to another automated storage and retrieval system), to a transport vehicle (e.g. a train or a lorry), or to a production facility.

A conveyor system comprising conveyors is normally employed to transport the storage containers between the ports and the access station. If the port and the access station are located at different levels, the conveyor system may comprise a lift device for transporting the storage containers vertically between the port and the access station.

The conveyor system may be arranged to transfer storage containers between different grids, e.g. as is described in WO2014/075937A1, the contents of which are incorporated herein by reference. WO2016/198467A1 , the contents of which are incorporated herein by reference, disclose an example of a prior art access system having conveyor belts (Figs. 5a and 5b) and a frame mounted track (Figs. 6a and 6b) for transporting storage containers between ports and work stations where operators can access the storage containers. When a storage container 6 stored in the grid 4 disclosed in Fig. 1 is to be accessed, one of the container-handling vehicles 9 is instructed to retrieve the target storage container from its position in the grid 4 and transport it to the drop -off port 19. This operation involves moving the container-handling vehicle to a grid location above the storage column in which the target storage container is positioned, retrieving the storage container from the storage column using the container -handling vehicle's lifting device (not shown), and transporting the storage container to the drop-off port 19. If the target storage container is located deep within a stack 7, i.e. with one or a plurality of other storage containers positioned above the target storage container, the operation also involves temporarily moving the above-positioned storage containers prior to lifting the target storage container from the storage column. This step, which is sometimes referred to as "digging" within the art, may be performed with the same container-handling vehicle that is subsequently used for transporting the target storage container to the drop -off port 19, or with one or a plurality of other cooperating container-handling vehicles. Alternatively, or in addition, the automated storage and retrieval system may have container -handling vehicles specifically dedicated to the task of temporarily removing storage containers from a storage column. Once the target storage container has been removed from the storage column, the temporarily removed storage containers can be repositioned into the original storage column. However, the removed storage containers may alternatively be relocated to other storage columns.

When a storage container 6 is to be stored in the grid 4, one of the container- handling vehicles 9 is instructed to pick up the storage container from the pick-up port 20 and transport it to a grid location above the storage column where it is to be stored. After any storage containers positioned at or above the target position within the storage column stack have been removed, the container-handling vehicle 9 positions the storage container at the desired position. The removed storage containers may then be lowered back into the storage column, or relocated to other storage columns.

For monitoring and controlling the automated storage and retrieval system, e.g. monitoring and controlling the location of respective storage containers within the grid 4, the content of each storage container 6 and the movement of the container- handling vehicles 9 so that a desired storage container can be delivered to the desired location at the desired time without the container-handling vehicles 9 colliding with each other, the automated storage and retrieval system comprises a control system, which typically is computerised and comprises a database for keeping track of the storage containers. A problem associated with known automated storage and retrieval systems is that the area surrounding the drop -off port and/or the pick-up port may become congested with container-handling vehicles instructed to drop off or pick up storage containers. This may seriously impede the operation of the automated storage and retrieval system.

A further problem associated with known automated storage and retrieval systems is the use of conveyor belts in transportation systems for transferring storage containers between the storage grid and a container handling station. Conveyor belts are both expensive and maintenance intensive. Especially the high maintenance requirements are to be avoided in a storage system that should preferably be operational 24/7.

In view of the above, it is desirable to provide an automated storage and retrieval system, and a method for operating such a system that solves or at least mitigates the aforementioned problem related to congestion of container-handling vehicles at the ports columns and/or the use of conveyor belts.

Summary of the invention

The present invention is defined in the attached claims and in the following:

In a first aspect, the present invention provides an automated storage and retrieval system comprising a three-dimensional grid and multiple container handling vehicles, wherein the three-dimensional grid comprises multiple storage columns, in which containers are stored one on top of another in vertical stacks, and multiple port columns through which the containers can be transferred between the top level of the grid and a container handling station; and the container handling vehicles are operated on a top level of the grid for retrieving containers from, and storing containers in, the storage columns and for transporting the containers horizontally across the grid to or from the multiple port columns; wherein

the container handling station comprises a horizontal container carousel comprising a first straight conveyor section and a second straight conveyor section interconnected by two intermediate conveyor sections, each of the conveyor sections comprises at least one conveyor device for

accommodating and moving a container in a horizontal direction;

the first straight conveyor section is arranged directly below the multiple port columns, such that any of the container handling vehicles may transfer a container between the top level of the grid and the first straight conveyor section via any of the multiple port columns; and

the second straight conveyor section is arranged to allow access to a container, wherein the container is retrieved from the grid via the first conveyor section (in other words, the second straight conveyor section is arranged to allow access to a container retrieved from the grid, wherein the container during use is initially positioned on the first straight conveyor section and then transported via one of the intermediate conveyor sections to the second straight conveyor section).

Preferably, each container handling vehicle comprises a container lift device able to lower or raise a container between the top level of the grid and the lowest level of a storage column or the first straight conveyor section.

In one embodiment of the automated storage and retrieval system, the container carousel is arranged within a support frame. Preferably, an upper part of the support frame arranged above the first conveyor section is connected to the lowermost ends of the multiple port columns. That is, the upper part of the support frame is connected to the lower ends of the upright members making up the multiple port columns.

Preferably, the intermediate conveyor sections are curved.

In a further embodiment of the automated storage and retrieval system, the multiple port columns comprise at least two adjacent port columns, preferably at least three adjacent port columns, even more preferred at least four adjacent port columns or most preferred at least five adjacent port columns.

In yet an embodiment of the automated storage and retrieval system, the container handling station comprises a work surface with a container access opening, and the second straight conveyor section is arranged below the work surface, such that an operator may access a container via the container access opening.

In yet an embodiment of the automated storage and retrieval system, the container access opening allows access to at least two adjacent containers arranged on the second conveyor section, preferably the container access opening provides access to at least three adjacent containers arranged on the second conveyor section.

In yet an embodiment of the automated storage and retrieval system, each of the conveyor devices is a container carriage and the horizontal container carousel, or each conveyor section, comprises multiple pivotably interconnected container carriages forming an endless chain. That is, each container carriage constitutes a link of the endless chain. In one embodiment, each container carriage is pivotably connected to an adjacent container carriage at an innermost corner of the carriage. Preferably, the endless chain consists of the first straight conveyor section, the second straight conveyor section and the two intermediate conveyor sections. Each container carriage is arranged to support and/or accommodate a single storage container and in one embodiment the container carriage comprises a frame featuring a bottom support, a first side wall and a second side wall arranged on opposite edges of the bottom support, and two opposite end walls.

In yet an embodiment of the automated storage and retrieval system, the first straight conveyor section comprises at least two adjacent container carriages arrangeable directly below at least two adjacent port columns, preferably the first straight conveyor section comprises at least three, four or five container carriages, wherein each of the container carriages is arrangeable directly below a

corresponding number of adjacent port columns.

In yet an embodiment of the automated storage and retrieval system, the multiple port columns comprise at least two adjacent port columns dedicated for transfer of a container from the first straight conveyor section to the top level of the grid, and at least two adjacent port columns dedicated for transfer of a container from the top level of the grid to the first straight conveyor section

In yet an embodiment of the automated storage and retrieval system, the first straight conveyor section and the second conveyor section are parallel.

In yet an embodiment of the automated storage and retrieval system, the horizontal container carousel comprises at least two horizontal drive wheels, the two horizontal drive wheels are spaced apart and the endless chain is operatively connected to an outer periphery of the drive wheels, such that the endless chain will move when the drive wheels rotate. At least one of the drive wheels is connected to a motor able to rotate the drive wheel. A drive wheel not connected to a motor may alternatively be termed a guide wheel.

In yet an embodiment of the automated storage and retrieval system, each of the container carriages is supported by a roller arrangement. The roller arrangement may comprise any suitable arrangement for supporting the container carriages, while allowing them to move in the horizontal plane, such as support wheels and wheel-like devices such as roller balls and rollers.

In yet an embodiment of the automated storage and retrieval system, the roller arrangement comprises an outer support wheel and two inner support wheels.

In yet an embodiment of the automated storage and retrieval system, each of the container carriages share an inner support wheel with an adjacent container carriage.

In yet an embodiment of the automated storage and retrieval system, each of the container carriages is supported by an outer support wheel and two inner support wheels and features a first side section and a second side section, the first side section being part of an inner periphery of the endless chain and the second side section being part of an outer periphery of the endless chain. Preferably, the roller arrangement of the container carriages run upon a horizontal surface of a support element arranged within the support frame of the container handling station.

In yet an embodiment, each of the container carriages share an inner support wheel with an adjacent container carriage.

In yet an embodiment of the automated storage and retrieval system, the outer support wheel is centrally arranged at the second side section, and the two inner support wheels are arranged at opposite ends of the first side section.

In yet an embodiment of the automated storage and retrieval system, the outer periphery of each drive wheel comprises multiple recesses, and a vertical shaft is arranged at each of the pivotable connections between the container carriages, each recess is arranged to accommodate a vertical shaft, such that the endless chain is operatively connected to the outer periphery of the drive wheels.

In yet an embodiment of the automated storage and retrieval system, the outer periphery of each drive wheel comprises multiple recesses and each pivotable connection between the container carriages comprises a vertical shaft.

Preferably, the centreline of a pivotable connection and its corresponding vertical shaft is aligned. Each recess is arranged to accommodate the vertical shaft of a pivotable connection, such that the endless chain is operatively connected to the outer periphery of the drive wheels, i.e. the endless chain is moved when the drive wheels rotate.

Preferably, each of the inner support wheels is connected to a corresponding vertical shaft of, or at, a pivotable connection.

In yet an embodiment of the automated storage and retrieval system, each container carriage comprises two opposite end sections, each end section facing an end section of an adjacent container carriage, and the first end section comprises at least one connecting element pivotably connected to an adjacent container carriage and extending beyond one of the end sections such that facing end sections of the two adjacent container carriages are spaced apart.

In yet an embodiment of the automated storage and retrieval system, the outer support wheel is centrally arranged at and/or adjacent to the second side section, and the two inner support wheels are arranged at and/or adjacent to opposite ends of the first side section.

In yet an embodiment of the automated storage and retrieval system, each of the container carriages is pivotably connected to two adjacent container carriages at opposite ends of the first side section, and each of the two inner support wheels is arranged at a corresponding pivotable connection to an adjacent container carriage, preferably, each of the two inner support wheels are connected to a vertical shaft aligned with and/or part of the corresponding pivotable connection.

In yet an embodiment of the automated storage and retrieval system, the grid comprises multiple intermediate storage columns adjacent to the multiple port columns.

In a second aspect, the present invention provides a method of storing or retrieving a product from an automated storage and retrieval system according to any embodiment of the first aspect, comprising the steps of:

retrieving a target container from the grid by use of a container handling vehicle, the target container contains the product to be retrieved or is intended for receiving the product to be stored;

lowering the target container from the top level of the grid to the first straight conveyor section via any of the multiple port columns by use of a container handling vehicle; (the target container is transferred by use of the container handling vehicle, i.e. lowered from the top level to the first straight conveyor section by use of the container lifting device of the container handling vehicle)

transferring the target container from the first straight conveyor section to the second straight conveyor section by moving the conveyor devices; - retrieving the product from, or introducing the product into, the target container;

transferring the target container from the second straight conveyor section to the first straight conveyor section;

raising the target container from the first straight conveyor section to the top level of the grid via any of the multiple port columns by use of a container handling vehicle; (the target container is transferred by use of the container handling vehicle, i.e. raised from the first straight conveyor section to the top level by use of the container lifting device of the container handling vehicle) and

- returning the target container to a storage column.

In one embodiment of the method of storing or retrieving a product from an automated storage and retrieval system, the target container is lowered from the top level of the grid to a first position on the first straight conveyor section via a first port column, and the target container is raised from a second position on the first straight conveyor section to the top level of the grid via a second port column, the first and second positions are arranged such that the target container will have a shorter travel distance from the first position to the second straight conveyor section compared to the travel distance from the second position to the second straight conveyor section, when the conveyor devices are moved (i.e. moved in the same rotational direction).

In one embodiment of the method of storing or retrieving a product from an automated storage and retrieval system, the step of retrieving a target container from the grid, comprises intermediate storing of the target container in an intermediate storage column.

In a third aspect, the present invention provides a container handling station suitable for an automated storage and retrieval system according to the first aspect, featuring a horizontal container carriage carousel comprising multiple container carriages and at least two horizontal drive wheels, wherein the multiple container carriages are pivotally interconnected forming an endless chain comprising a first straight conveyor section and a second straight conveyor section, the straight conveyor sections being parallel and interconnected by two intermediate curved conveyor sections, the endless chain has an inner and outer periphery; the at least two drive wheels are spaced apart, preferably in a common horizontal plane, and each drive wheel comprises an outer periphery operatively connected to the endless chain, such that the endless chain will move when the drive wheels rotate; the first straight conveyor section is arrangeable directly below multiple adjacent port columns in the grid of the automated storage and retrieval system; and the second straight conveyor section is arranged below a work surface having a container access opening through which an operator may access a container. The container handling station may optionally comprise any of the features related to the container handling station of the automated storage and retrieval system according to the first aspect.

The term "horizontal container carousel" is in the context of the present

specification intended to define a container transport assembly having a looped horizontal transport path, wherein a container may be transported from an initial position, around the looped transport path and back to the initial position.

The term "conveyor device" is in the context of the present specification intended to define any element or device suitable for transporting a storage container in a horizontal direction, such as a conveyor belt, rollers and carriages. The conveyor sections of a horizontal container carousel may comprise the same or different types of conveyor devices, provided a looped transport path is obtained. Drawings

The present invention is described in detail by reference to the following drawings:

Fig. 1 is a perspective view of a grid of a prior art automated storage and retrieval system. Fig. 2 is a perspective view of a prior art container handling vehicle.

Fig. 3 is a top view of a prior art single rail grid.

Fig. 4 is a top view of a prior art double rail grid.

Fig. 5 is a perspective view of a storage and retrieval system according to the invention.

Fig. 6 are a front side view and a side view of the system in fig. 5.

Fig. 7 is a topside view of the system in fig 5.

Fig. 8 is a perspective view of a container handling station according to the invention.

Fig. 9 is a perspective view of the container handling station in fig. 8, wherein the work surface and side panels are removed for illustrative purposes.

Fig. 10 is a partially transparent topside view of the container handling station in fig. 8.

Fig. 11 is a partially transparent front view of the container handling station in fig. 8.

Fig. 12 is a cross-sectional view of the container handling station in fig. 8.

Fig. 13 is a perspective view of the container carriage carousel of the container handling station in fig. 8. In the drawings, like reference numerals have been used to indicate like parts, elements or features unless otherwise explicitly stated or implicitly understood from the context.

Detailed description of the invention

In the following, embodiments of the invention will be discussed in more detail by way of example only and with reference to the appended drawings. It should be understood, however, that the drawings are not intended to limit the invention to the subject-matter depicted in the drawings.

An embodiment of an automated storage and retrieval system according to the invention will now be discussed in more detail with reference to Figs. 5- 13.

A perspective view and two side views of an embodiment of an automated storage and retrieval system according to the invention is shown in figs. 5 and 6. The main components of the disclosed system are the grid 4, comprising storage columns 5 and five adjacent port columns 19,20, the container handling vehicles 9 and the container handling station 21. In the embodiment of figs. 5- 13, only a section of the whole grid 4 is shown.

The container handling station 21 features a horizontal container carousel 24 arranged within a support frame 41 (see Fig. 9). The lower end of the adjacent port columns, i.e. the lower ends of the upright members 2 making up the port columns, are connected to the support frame 41. The container carousel 24 comprises a first straight conveyor section 25 and a second straight conveyor section 26

interconnected by two curved conveyor sections 27, 27' . The conveyor sections are made up of multiple pivotably interconnected container carriages 29 (i.e. conveyor devices) forming an endless chain 46. The container carriages comprise support wheels 32, 33.

The endless chain of container carriages is operatively connected to recesses 31 at the outer periphery of two horizontal drive wheels 30 via wheel connecting shafts 36. The shafts 36 are aligned with, or is a part of, pivotable connections 37 between the container carriages 29. In this embodiment, the support wheels 32, 33 are swivel wheels providing an improved wheel tracking along the curved conveyor sections. In addition, the swivel wheels enable a simple construction in that the vertical wheel connecting shaft 36 of the swivel wheels arranged at the inner circumference of the endless chain may provide both the pivot coupling between the container carriages 29 and the operative connection to the horizontal drive wheels 30.

Consequently, all adjacent container carriages share a support wheel 33. Rotational movement of the container carousel 24 is obtained by the motor 39 connected to one of the drive wheels.

Each carriage 29 is designed as a frame comprising a bottom support 43 and four side walls, defining a first side section 34, a second side section 35 and two opposite end sections 28,28 '. The side sections and end sections comprise the side walls preventing an accommodated storage container 6 from moving relative the carriage 29 during transport on the carousel 24. The first side section constitutes an inner periphery of the endless chain and the second side section 34 forms at least parts of the outer periphery of the endless chain.

To obtain a stable platform for accommodating a storage container 6, each of the container carriages 29 is supported by an outer support wheel 32, centrally arranged at the second side section 35, and two inner support wheels 33. The inner support wheels 33 are connected to the wheel connecting shafts 36 and arranged at opposite ends of the first side section 34. The support wheels 32,33 of the container carriages 29 run on top of a horizontal support surface 45 of the support element 40.

Each end section 28,28' of a container carriage faces an end section of an adjacent container carriage, at least while the carriages 29 are running along a straight section 25, 26. The first side section 34 comprises a connecting element 38 pivotably connected to the connecting element 38 of an adjacent container carriage. The connecting element 38 extends beyond the end sections 28, 28 ' of the carriage 29, such that facing end sections 28, 28 Of two adjacent container carriages 29 are spaced apart.

The first straight conveyor section 25 is arranged directly below the multiple port columns 19,20, such that any of the container handling vehicles 9 may transfer a storage container 6 between the top level of the grid 4 and the first straight conveyor section 25 via any of the multiple port columns 19, 20. In other words , each port column 19, 20 comprises a lower end arranged directly above the first straight conveyor section 25. The port columns 19, 20 are arranged to guide the vertical movement of a storage container 6 preventing the container 6 from moving in a horizontal direction until it is positioned on the first straight conveyor section

25 or has arrived at the top level of the grid 4. The second straight conveyor section

26 is parallel to the first straight conveyor section and is arranged to allow access to a container retrieved from the grid via the first conveyor section. The second straight conveyor section 26 is arranged below a work surface 22 of the container handling station and an operator may obtain access to a container arranged on the second straight conveyor section 26 via the container access opening 23 in the work surface 22. In the present embodiment, the container access opening 23 allows access to three adjacent storage containers 6 at the same time. The possibility of accessing multiple adjacent storage containers is advantageous in that the operator have more flexibility in managing the time spent in processing each storage container.

The disclosed automated storage and retrieval system allows for a highly efficient method of storing or retrieving a product from a target container in a storage grid. The method may advantageously comprise the following steps:

retrieving a target container 6 from the grid 4 by use of a container handling vehicle 9, the target container 6 contains the product to be retrieved or is intended for receiving the product to be stored; lowering the target container 6 from the top level of the grid 4 to a first straight conveyor section 25 via any of multiple port columns 19,20 by use of a container handling vehicle 9 - i.e. the target container is lowered from the top level to a first straight conveyor section 25 by use of the container lifting device of the vehicle 9 ;

rotating the drive wheels 30, such that the target container 6 is transferred from the first straight conveyor section 25 to a second straight conveyor section 26;

retrieving the product from, or introducing the product into, the target container 6; rotating the drive wheels 30, such that the target container 6 is transferred from the second straight conveyor section 26 to the first straight conveyor section 25;

raising the target container 6 from the first straight conveyor section 25 to the top level of the grid 4 via any of the multiple port columns 19, 20 by use of a container handling vehicle 9; and

returning the target container to a storage column.

The rotational direction of the drive wheel 30, and consequently, the direction in which the conveyor sections 25, 26, 27, 27' move, is the same for all steps of the method, when the drive wheels are rotated.

During use, the multiple port columns 19, 20 may for instance comprise two adjacent port columns 20 dedicated for transfer of a container 6 from the first straight conveyor section 25 to the top level of the grid 4, and two adjacent port columns 19 dedicated for transfer of a container 6 from the top level of the grid 4 to the first straight conveyor section 25. In other instances, none or any one, of the port columns are dedicated for a particular transfer function. The multiple adjacent port columns 19, 20 provide a highly flexible system for transfer of products and storage containers 6 in/out of the storage grid 4.

For example, in an embodiment of the above method, the target container 6 is lowered from the top level of the grid 4 to a first position 42 on the first straight conveyor section via a first port column 19, and the target container 6 is raised from a second position 42' on the first straight conveyor section 25 to the top level of the grid via a second port column 20. The first and second positions 42, 42' are arranged such that the target container 6 will have a shorter travel distance from the first position to the second straight conveyor section 26 when moving in the rotational direction of the drive wheels 30 compared to the travel distance from the second position 42' .

The system may also comprise multiple storage columns dedicated for intermediate storage of containers before or after transfer to/from the container handling station, i.e. intermediate storage columns 5 ' . The intermediate storage columns provide a storage buffer allowing for an improved logistics management. Thus, in the above described method, the step of retrieving a target container from the grid 4 may advantageously comprise intermediate storing of the target container in an intermediate storage column ' .

The invention is described by reference to a single embodiment, wherein the conveyor devices are container carriages 29. Although this is a preferred

embodiment, due to the low cost and low maintenance of such a container carousel design, other embodiments, wherein the conveyor devices comprise various types of container carriages, conveyor belts, rollers and similar solutions, would also provide an advantageous storage system due to the inherent flexibility of the general design of the container handling station. In preferred alternative embodiments, other suitable designs of container carriages may include any type of carriage, dolly or trolley featuring a support surface for accommodating a single storage container.

The support surface may be part of a horizontal frame, plate or similar element. The container carriages are preferably at least partially supported by a wheel

arrangement. The general design featuring a looped transport path comprising a straight conveyor section, allows for the use of multiple adjacent port columns, wherein each port column may be used for transfer of a storage container both to and from the grid depending on the current logistics needs.