Patent Description:
<FIG> and <FIG> disclose a typical prior art automated storage and retrieval system <NUM> with a framework structure <NUM>. <FIG> and <FIG> disclose prior art container handling vehicles <NUM>,<NUM> operating in the system <NUM> disclosed in <FIG> and <FIG>, respectively.

The framework structure <NUM> defines a storage grid <NUM> comprising a plurality of upright members <NUM> and optionally a plurality of horizontal members <NUM> supporting the upright members <NUM>. The members <NUM>, <NUM> may typically be made of metal, e.g. extruded aluminium profiles.

The storage grid <NUM> comprises multiple grid columns <NUM>. A large majority of the grid columns are also termed storage columns <NUM>, in which storage containers <NUM>, also known as bins, are stacked one on top of another to form stacks <NUM>.

Each storage container <NUM> may typically hold a plurality of product items (not shown), and the product items within a storage container <NUM> may be identical or may be of different product types depending on the application.

The storage grid <NUM> guards against horizontal movement of the of storage containers <NUM> in the stacks <NUM>, and guides vertical movement of the containers <NUM>, but does normally not otherwise support the storage containers <NUM> when stacked.

The automated storage and retrieval system <NUM> comprises a rail system <NUM> (or a top rail grid) arranged in a grid pattern across the top of the storage grid <NUM>, on which rail system <NUM> a plurality of container handling vehicles <NUM>,<NUM> (as exemplified in <FIG> and <FIG>) are operated to raise storage containers <NUM> from, and lower storage containers <NUM> into, the storage columns <NUM>, and also to transport the storage containers <NUM> above the storage columns <NUM>. The horizontal extent of one of the grid cells <NUM> constituting the grid pattern is in <FIG> and <FIG> marked by thick lines.

Each grid cell <NUM> has a width which is typically within the interval of <NUM> to <NUM>, and a length which is typically within the interval of <NUM> to <NUM>. Each grid opening <NUM> has a width and a length which is typically <NUM> to <NUM> less than the width and the length of the grid cell <NUM> due to the horizontal extent of the rails <NUM>,<NUM>.

In this way, the rail system <NUM> defines the upper ends of the grid columns <NUM> above which the container handling vehicles <NUM>,<NUM> can move laterally, i.e. in a plane which is parallel to the horizontal X-Y plane. Commonly, at least one of the sets of rails <NUM>,<NUM> is made up of dual-track rails allowing two container handling vehicles to pass each other on neighbouring grid cells <NUM>. Dual-track rails are well-known and disclosed in for instance <CIT> and <CIT>.

Each prior art container handling vehicle <NUM>,<NUM> comprises a vehicle body and a wheel arrangement of eight wheels <NUM>,<NUM>, wherein a first set of four wheels enable the lateral movement of the container handling vehicles <NUM>,<NUM> in the X direction and a second set of the remaining four wheels enable the lateral movement in the Y direction. One or both sets of wheels in the wheel arrangement can be lifted and lowered, so that the first set of wheels and/or the second set of wheels can be engaged with the respective set of rails <NUM>, <NUM> at any one time.

Each prior art container handling vehicle <NUM>,<NUM> also comprises a lifting device (not shown) for vertical transportation of storage containers <NUM>, e.g. raising a storage container <NUM> from, and lowering a storage container <NUM> into, a storage column <NUM>. The lifting device comprises one or more gripping/engaging devices (not shown) which are adapted to engage a storage container <NUM>, and which gripping/engaging devices can be lowered from the vehicle <NUM>,<NUM> so that the position of the gripping/engaging devices with respect to the vehicle <NUM>,<NUM> can be adjusted in a third direction Z which is orthogonal the first direction X and the second direction Y.

Conventionally, and also for the purpose of this application, Z=<NUM> identifies the uppermost layer of the grid <NUM>, i.e. the layer immediately below the rail system <NUM>, Z=<NUM> the second layer below the rail system <NUM>, Z=<NUM> the third layer etc. In the prior art storage grid disclosed in <FIG> and <FIG>, Z=<NUM> identifies the lowermost, bottom layer of the grid <NUM>. Consequently, as an example, and using the Cartesian coordinate system X, Y, Z indicated in <FIG> and <FIG>, the storage container identified as <NUM>' in <FIG> can be said to occupy grid location or cell X=<NUM>, Y=<NUM>, Z=<NUM>. The container handling vehicles <NUM>,<NUM> can be said to travel in layer Z=<NUM> and each grid column can be identified by its X and Y coordinates.

Each container handling vehicle <NUM> comprises a storage compartment or space (not shown) for receiving and stowing a storage container <NUM> when transporting the storage container <NUM> across the top of the storage grid <NUM>. The storage space may comprise a cavity arranged centrally within the vehicle body, e.g. as is described in <CIT>.

Alternatively, the container handling vehicles <NUM> may have a cantilever construction as described in <CIT>.

The container handling vehicles <NUM> may have a footprint, i.e. an extent in the X and Y directions, which is generally equal to the horizontal area of a grid cell <NUM>, i.e. the extent of a grid cell <NUM> in the X and Y directions, e.g. as is described in <CIT>.

Alternatively, the container handling vehicles <NUM> may have a footprint which is larger than the horizontal area of a grid cell <NUM>, e.g. as is disclosed in <CIT>.

In a storage grid <NUM>, a majority of the grid columns <NUM> are storage columns <NUM>, i.e. grid columns where storage containers <NUM> are stored in stacks <NUM>. However, a grid <NUM> normally has at least one grid column <NUM> which is not used for storing storage containers <NUM>, but is arranged at a location wherein the container handling vehicles <NUM>,<NUM> can drop off and/or pick up storage containers <NUM> so that they can be transported to a second location (not shown) where the storage containers <NUM> can be accessed from outside of the grid <NUM> or transferred out of or into the grid <NUM>. Within the art, such a location is normally referred to as a "port" and the grid column at which the port is located may be referred to as a transfer column <NUM>,<NUM>. The drop-off and pick-up ports are the upper ends/openings of a respective transfer column <NUM>,<NUM>.

The prior art storage grids <NUM> in <FIG> and <FIG> comprise two transfer columns <NUM> and <NUM>. The first transfer column <NUM> may for example comprise a dedicated drop-off port where the container handling vehicles <NUM>,<NUM> can drop off storage containers <NUM> to be transported through the transfer column <NUM> and further to e.g. a picking/stocking station, and the second transfer column <NUM> may comprise a dedicated pick-up port where the container handling vehicles <NUM>,<NUM> can pick up storage containers <NUM> that have been transported through the transfer column <NUM> from e.g. a picking/stocking station. A storage container may be transported through a transfer column by use of the lifting device of a container handling vehicle <NUM>,<NUM> or by use of a storage container lift arranged in the transfer column. Each of the ports of the first and second transfer column may be suitable for both pick-up and drop-off of storage containers.

The second location may typically be a picking/stocking station, wherein product items are removed from and/or positioned into the storage containers <NUM>. In a picking/stocking station, the storage containers <NUM> are normally never removed from the automated storage and retrieval system <NUM> but are returned into the storage grid <NUM> once accessed.

For monitoring and controlling the automated storage and retrieval system <NUM>, e.g. monitoring and controlling the location of respective storage containers <NUM> within the storage grid <NUM>; the content of each storage container <NUM>; and the movement of the container handling vehicles <NUM>,<NUM> so that a desired storage container <NUM> can be delivered to the desired location at the desired time without the container handling vehicles <NUM>,<NUM> colliding with each other, the automated storage and retrieval system <NUM> comprises a computerized control system (not shown) which typically comprises a database for keeping track of the storage containers <NUM>.

A conveyor system comprising conveyor belts or rollers is commonly employed to transport the storage containers from a lower end of the transfer columns <NUM>,<NUM> to e.g. a picking/stocking station.

A conveyor system may also be arranged to transfer storage containers between different storage grids, e.g. as is described in <CIT>.

Further, <CIT> discloses an example of a prior art access system having conveyor belts (Figs. 5a and 5b in <CIT>) and a frame mounted rail (Figs. 6a and 6b in <CIT>) for transporting storage containers between transfer columns and stations where operators can access the storage containers.

When a storage container <NUM> stored in the storage grid <NUM> disclosed in <FIG> is to be accessed, one of the container handling vehicles <NUM>,<NUM> is instructed to retrieve the target storage container <NUM> from its position in the grid <NUM> and transport it to or through the transfer column <NUM>. This operation involves moving the container handling vehicle <NUM>,<NUM> to a grid location above the storage column <NUM> in which the target storage container <NUM> is positioned, retrieving the storage container <NUM> from the storage column <NUM> using the container handling vehicle's lifting device (not shown), and transporting the storage container <NUM> to the transfer column <NUM>. If the target storage container <NUM> is located deep within a stack <NUM>, i.e. with one or a plurality of other storage containers positioned above the target storage container <NUM>, the operation also involves temporarily moving the above-positioned storage containers prior to lifting the target storage container <NUM> from the storage column <NUM>. This step, which is sometimes referred to as "digging" within the art, may be performed with the same container handling vehicle <NUM>,<NUM> that is subsequently used for transporting the target storage container <NUM> to the transfer column, or with one or a plurality of other cooperating container handling vehicles <NUM>,<NUM>. Alternatively, or in addition, the automated storage and retrieval system <NUM> may have container handling vehicles <NUM>,<NUM> specifically dedicated to the task of temporarily removing storage containers <NUM> from a storage column <NUM>. However, the removed storage containers may alternatively be relocated to other storage columns <NUM>.

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

A problem associated with known automated storage and retrieval systems <NUM> is that the area surrounding the pick-up and drop-off ports may become congested with container handling vehicles <NUM>,<NUM> instructed to drop off or pick up storage containers <NUM>. This may seriously impede the operation of the automated storage and retrieval system <NUM>. In small systems this situation may possibly be alleviated by adding further transfer columns to the grid, as this will allow the container handling vehicles <NUM>,<NUM> to be distributed among a larger number of ports of transfer columns in order to avoid congestion. However, if further ports and columns are added, the number of picking/stocking stations as well as the conveyor system infrastructure must be increased. This requires space, which may not necessarily be available. Also, adding conveyor system infrastructure and additional picking/stocking stations is costly.

In the prior art solutions for transfer of storage containers out of or into the storage grid, the ports and the respective transfer columns <NUM>,<NUM> are required to be arranged at a grid column <NUM> in/at the periphery of the storage grid, or the ports are arranged at an extension of the rail system <NUM> extending beyond the grid columns <NUM> at the periphery of the storage grid <NUM>. Examples of such prior art solutions are disclosed in for instance <CIT>, <CIT>, <CIT> and <CIT>. This requirement entails that the number of transfer columns <NUM>,<NUM> and any associated structure for storage container handling, such as picking/stocking stations, are restricted by the available space at the periphery of the storage grid. Further, by having the transfer columns <NUM>,<NUM> arranged at or outside the periphery of the storage grid, the container handling vehicles are often required to travel long distances upon the storage grid to reach the closest port. The latter is a hindrance to obtaining an optimum efficiency, in particular when operating large storage grids, wherein the distance from a centre section of the storage grid to the periphery is long. Finally, <CIT> describes, in accordance with its abstract, systems, methods and machine-executable coded instruction sets for the fully- and/or partly automated handling of goods. In particular, the disclosure provides developments in the storage and retrieval of containers in systems such as order processing systems wherein containers may be brought to a grid, engaged by an overhead load handler at a port or a bottom-access lifter/ clamp, and stored within a stack of the grid until needed for further order fulfillment processes and wherein at the port, the container can be lowered to or otherwise placed on a conveyor or other conveyance for delivery to a an order picking station.

A further issue with the prior art solutions is the lack of flexibility regarding the handling of storage containers exiting or entering the storage grid. That is, a storage container from which an item is to be picked or in which an item is to be stocked must be delivered to a port specifically designated for the purpose of picking/stocking items. Similarly, a storage container exiting the grid for the purpose of being transported to e.g. a neighbouring storage grid or assembly line must be delivered to a port specifically designated for this purpose.

Some of the above-mentioned issues regarding flexibility may be solved by use of extensive conveyor systems, i.e. conveyor belts, rollers etc., as well as dedicated storage container lifts. However, such systems are expensive, service intensive and are vulnerable to single point of failure events that may disrupt the operation of the storage system.

An efficiency issue with prior art automated storage and retrieval systems <NUM> is that the separate drop-off ports and pick-up ports of the transfer columns <NUM>,<NUM> require the container handling vehicles <NUM>,<NUM> to move to a storage column <NUM> or a pick-up port after drop-off to retrieve a new storage container <NUM>. Likewise, the container handling vehicles <NUM>,<NUM> have to be empty of a storage container <NUM> when they are sent to a pick-up port <NUM> to pick up a storage container. This is often inefficient and causes increased congestion around the ports, as container handling vehicles <NUM>,<NUM> are moving around on the grid without a storage container <NUM> as payload.

Yet an efficiency issue with prior art automated storage and retrieval systems is the way items to be shipped out are transported from a picking/stocking stations, wherein the items are packed in boxes, to a loading station wherein the packed items are for instance loaded onto a truck for transport to a customer.

In view of the above, the aim of the present invention is to provide an automated storage and retrieval system, and a method for operating such a system, that solves or at least mitigates one or more of the aforementioned problems related to the use of prior art storage and retrieval systems.

The main objective of the present invention is to provide an automated storage and retrieval system in which items may be transported between a picking/stocking station of the storage system and a site external to the storage system in a more efficient manner.

The present invention is defined by the appended claims and in the following:
In a first aspect, the present invention provides a storage system comprising a storage grid structure having a top rail grid upon which container handling vehicles work to store and retrieve storage containers in and from storage columns beneath the top rail grid, wherein the storage system comprises multiple transfer rails forming a horizontal transfer rail grid arranged at a level below the top rail grid, at least one transport vehicle operating on the transfer rail grid, a picking/stocking station for picking/stocking items between a storage container and a packaging box, and an unloading/loading assembly for unloading/loading packaging boxes containing such items, the transport vehicle is arranged to move upon the transfer rail grid in two perpendicular directions and comprises a carrier platform, wherein the transfer rail grid is arranged to allow access for the transport vehicle to transport one or more packaging boxes at a time between the picking/stocking station and the unloading/loading assembly.

In other words, the transfer rail grid extends between the picking/stocking station and the unloading/loading assembly such that an item picked from a storage container and loaded onto the transport vehicle may be transported by the transport vehicle from the picking/stocking station to the unloading/loading assembly.

In other words, the picking/stocking station is for picking/stocking items from/in a storage container after retrieving the storage container from the storage grid or before introducing the storage container into the storage grid. The picking/stocking station is, according to the invention to which this European patent relates, operatively connected to a transfer column of the storage grid structure, such that a storage container may be transferred between the picking/stocking station and a storage column.

The unloading/loading assembly may comprise any of a pallet lifter and/or a conveyor system arranged to load/unload packaging boxes and/or pallets to/from the transport vehicle.

In other words, the transfer rail grid may be arranged such that the transport vehicle can access or be arranged at the unloading/loading assembly.

Alternatively, the storage system may be defined as comprising the unloading/loading assembly.

In an embodiment of the storage system, the transfer rail grid may comprise a transfer grid area at which the unloading/loading assembly is arranged.

In an embodiment of the storage system, the carrier platform may be arranged to support a pallet. In other words, the transport vehicle may be suitable for transporting one or more packaging boxes arranged on a pallet between the picking/stocking station and the unloading/loading assembly.

In an embodiment of the storage system, the storage grid structure may comprise vertical column profiles defining multiple storage columns, in which storage containers can be stored one on top of another in vertical stacks, and at least one transfer column, the column profiles are interconnected at their upper ends by top rails forming the horizontal top rail grid upon which the container handling vehicles may move in two perpendicular directions.

In an embodiment of the storage system, the transport vehicle may have a wheel arrangement comprising a first set of wheels enabling movement of the transport vehicle in a first direction and a second set of wheels enabling movement of the transport vehicle in a second direction perpendicular to the first direction, and each set of wheels comprises at least two pairs of wheels arranged on opposite sides of the transport vehicle.

In an embodiment of the storage system, the carrier platform may comprise a conveyor assembly arranged to move an item arranged on the carrier platform in a horizontal direction off the transport vehicle. The conveyor assembly may comprise any suitable conveyor solution, such as multiple rollers, a belt conveyor and/or a chain conveyor. The item movable by the conveyor assembly may be any type of packaging boxes, pallets and storage containers.

In an embodiment of the storage system, the transport vehicle may comprise at least two adjacently connected wheel base units upon which the carrier platform is arranged. Each wheel base unit may feature a wheel arrangement, wherein a first set of wheels enable movement of the transport vehicle in the first direction upon the transfer rail grid and a second set of wheels enable movement in the second direction, and each set of wheels comprises two pairs of wheels arranged on opposite sides of the wheel base unit.

In an embodiment of the storage system, each wheel arrangement may comprise eight wheels and each set of wheels may comprise four wheels.

One or both sets of wheels in the wheel arrangement may be lifted and lowered, so that the first set of wheels and/or the second set of wheels can be engaged with the respective set of rails at any one time.

In an embodiment of the storage system, each wheel base unit may have a horizontal periphery fitting within the horizontal area defined by a grid cell of the transfer rail grid.

In an embodiment of the storage system, the carrier platform may be sized to accommodate at least two of the storage containers side by side. The carrier platform may be sized to accommodate four of the storage containers, preferably adjacently arranged in a two by two configuration. An advantage of having the carrier platform sized to accommodate at least two storage containers is the possibility of using the transport vehicle for loading or retrieving storage containers to/from the storage grid structure. This feature may for instance facilitate the initial loading of storage containers to the storage system and the retrieval of used storage containers from the storage grid structure to be replaced due to wear.

In an embodiment of the storage system, the transport vehicle may comprise four connected wheel base units, preferably connected in a two by two configuration. In other words, the four wheel base units are adjacently arranged two by two.

In an embodiment of the storage system, at least the transfer rails may extend in one of two perpendicular directions of the transfer rail grid are dual-track rails, such that the transport vehicle may pass another transport vehicle upon an adjacent grid cell of the transfer rail grid when moving in the one direction.

In an embodiment of the storage system, the storage grid structure may comprise at least one horizontal transfer section, and.

In other words, the at least one transfer column may extend from the top rail grid to the transfer section, such that a storage container may be transferred between the top rail grid and the container carrier of one of the container transfer vehicles when the container transfer vehicle is arranged on the transfer rail grid at a position below the transfer column.

The at least one transfer column may also be defined as a column for vertical transfer of a storage container between different levels of the grid structure, preferably by use of a container handling vehicle.

The transfer section may in other words be defined as being arranged at a level below the level of the top rail grid.

In an embodiment of the storage system, the transfer grid area may be accessible by the container transfer vehicles and may be termed a multi-use transfer grid area.

In an embodiment of the storage system, at least the transfer rails may extend in one of two perpendicular directions of the transfer rail grid may be dual-track rails, such that the container transfer vehicles and/or the transport vehicles may pass each other upon adjacent grid cells of the transfer rail grid when moving in the one direction. In other words, the transfer rails of the transfer rail grid may extend in two perpendicular horizontal directions, and at least the transfer rails extending in one of the two perpendicular directions of the transfer rail grid may be dual-track rails, such that the container transfer vehicles and/or the transport vehicles may pass each other upon adjacent grid cells of the transfer rail grid when moving in the one direction.

In an embodiment of the storage system, the transfer rails may be dual-track rails, such that the container transfer vehicles and/or the transport vehicles may pass each other upon adjacent grid cells of the transfer rail grid.

In an embodiment of the storage system, each of the container transfer vehicles may have a horizontal periphery fitting within the horizontal area defined by a grid cell of the transfer rail grid. In other words, the transfer rail grid may comprise multiple grid cells defined by the transfer rail grid, and each of the container transfer vehicles may have a horizontal periphery fitting within the horizontal area defined by one of the grid cells of the transfer rail grid, such that the container transfer vehicles may pass each other upon adjacent grid cells of the transfer rail grid; in other words, such that the container transfer vehicles may pass each other when moving on adjacent grid cells of the transfer rail grid.

In an embodiment of the storage system, the height of the transfer section may be sufficient to allow a container transfer vehicle to travel within the transfer section when carrying a storage container.

The transfer rails may be defined as forming, providing, and/or being a part of, the transfer rail grid upon which the container transfer vehicles may move in at least one horizontal directions. Further, the container transfer vehicles may move in two perpendicular horizontal directions upon at least the section of the transfer rail grid being part of the transfer section. In other words, at least the transfer rail grid being part of the transfer section provides at least two perpendicular transfer vehicle paths, allowing a container transfer vehicle to move upon the transfer rail grid in two perpendicular directions.

In an embodiment of the storage system, at least a part of the transfer rail grid may be formed or provided by transfer rails arranged external to the storage grid. In other words, at least a part of the transfer rail grid may be arranged external to the storage grid.

In an embodiment of the storage system, the design of the transfer rails and the transfer rail grid may be similar, or identical, to the top rails and the top rail grid, respectively.

In an embodiment of the storage system, the transfer rail grid and the top rail grid may have substantially similar or identical dimensions. In other words, the transfer rails and the top rails provide respective rail grids having grid cells of the same horizontal extent and/or dimension. This feature is advantageous in that it allows for multiple adjacent transfer columns, through which storage containers may be transferred simultaneously to respective adjacent container transfer vehicles arranged in the transfer section.

In an embodiment of the storage system, the transfer rail grid may extend from the position below the at least one transfer column to a second position external to the storage grid structure. In other words, the transfer rail grid extends from the position below the at least one transfer column to a second position external to the storage grid structure, such that a container transfer vehicle may move from the position below the at least one transfer column to the second position.

In an embodiment of the storage system, the transfer rails may provide at least one transfer vehicle path extending from a position below the at least one transfer column to a second position external to the storage grid structure, i.e. such that a container transfer vehicle may move from the position below the at least one transfer column to the second position. The transfer rails may provide a plurality of transfer vehicle paths extending from a position below the at least one transfer column to the second position external to the storage grid structure.

In an embodiment of the storage system, the wheel arrangement of each container transfer vehicle may comprise eight wheels, wherein a first set of four wheels enable the lateral movement of the container transfer vehicle in a first direction and a second set of the remaining four wheels enable the lateral movement in a second direction being perpendicular to the first direction. One or both sets of wheels in the wheel arrangement is connected to a wheel lifting mechanism and can be lifted and lowered, so that the first set of wheels and/or the second set of wheels can be engaged with the respective set of transfer rails of the transfer rail grid at any one time.

In an embodiment of the storage system, each of the container handling vehicles may comprise a wheel arrangement similar to the wheel arrangement of the container transfer vehicles, for engaging the respective set of top rails of the top rail grid.

In an embodiment of the storage system, the at least one transfer column may extend from the top rail grid to the transfer section, such that a container handling vehicle may transfer a storage container between the top rail grid and the container carrier of one of the container transfer vehicles. Each of the container handling vehicles may comprise a lifting device for vertical transfer of a storage container.

In an embodiment of the storage system, the transfer section may extend from a first opening at an external side of the storage grid structure to at least a second opening at an external side of the storage grid structure. In other words, the transfer section extends through an internal section of the storage grid structure from a first opening at an external side of the storage grid structure to at least a second opening at the same or different external side of the storage grid structure The term "opening" is intended to mean a gap in the storage grid structure through which gap (or opening) at least one container transfer vehicle may pass while carrying a storage container. Preferably, the first and/or second opening have a width allowing the passage of at least two container transfer vehicles simultaneously.

In an embodiment of the storage system, the first and second openings may be arranged at separate external sides of the storage grid structure, preferably the first and second openings are arranged at opposite external sides of the storage grid structure.

In an embodiment of the storage system, the transfer rails and/or the transfer rail grid may provide at least two adjacent transfer vehicle paths, such that at least two of the container transfer vehicles may pass each other in the transfer section, i.e. may pass each other when moving on the transfer rails or the transfer rail grid in the transfer section. Preferably the transfer rail grid comprises dual-track rail allowing the container transfer vehicles to pass each other at adjacent grid cells of the transfer rail grid. In a further embodiment, the transfer rails, or the transfer rail grid, provides at least three transfer vehicle paths, such that at least three container transfer vehicles may pass each other in one direction within the transfer section. In an embodiment, the storage system may comprise multiple transfer columns.

In an embodiment of the storage system, the transfer section may extend below the multiple transfer columns. Preferably, the transfer section extends below multiple adjacent transfer columns.

In an embodiment of the storage system, the multiple transfer columns may be arranged above one of the transfer vehicle paths.

In an embodiment, each of the multiple transfer columns may be arranged above a grid cell of the transfer rail grid and may be arranged above only one grid cell i.e. above a respective grid cell of the transfer rail grid.

In a further embodiment, the multiple transfer columns may be arranged above only one of several (e.g. two or three) transfer vehicle paths. In this manner, one (or a single) vehicle path may be dedicated to container transfer vehicles receiving or delivering storage containers from/to the at least one transfer column, while the remaining vehicle paths are dedicated for transfer/movement of container transfer vehicles, optionally carrying a storage container, out of or into the transfer section.

In an embodiment of the storage system, the transfer rail grid may extend from an external side of the storage grid to a second position external to the storage grid structure.

In an embodiment of the storage system, the transfer rail grid may extend from the position below the at least one transfer column to a second position external to the storage grid structure. The second position may be at any suitable area, arrangement or station for further processing or transfer of a storage container or its content, or at any suitable position for parking of a container transfer vehicle, e.g. a charging station for the battery driving the container transfer vehicle or a temporary storage position of a storage container arranged on a container transfer vehicle.

In an embodiment of the storage system, the second position may be arranged at a picking/stocking station or area, such that an operator/robot may access the content of a storage container when arranged on a container transfer vehicle.

In an embodiment of the storage system, the second position may be below a transfer column in a transfer section of a second storage grid structure. The second storage grid structure comprises any of the features of the storage grid structure of the first aspect, and its embodiments, as defined above. Alternatively, the first aspect may be defined as a storage system comprising at least a first storage grid structure. In yet another embodiment, the transfer rails or transfer rail grid extends to a third position below a transfer column in a transfer section of a third storage grid structure. In a storage system comprising a first and a second storage grid structure, the second storage grid structure may be arranged at any level and/or position relative the first storage grid structure. When the first and a second storage grid structure are arranged at different levels, the transfer rail grid may comprise a container transfer vehicle lift for lifting a container transfer vehicle between separate levels of the transfer rail grid.

An advantage of the present invention is the possibility of easily interconnecting multiple separate storage grid structures and optionally any third-party storage system. This provides an increase in fire safety since the multiple storage grid structures are easily separated in a manner which prevents a fire from spreading from one storage grid structure to another. Further, the use of multiple separate storage grid structures allows for an improved utilization of available space in a storage house or location. Thus, the storage system of the first aspect may also comprise multiple storage grid structures. Each storage grid structure may be interconnected by the transfer rail grid, such that the container transfer vehicles may move between any of the multiple storage grid structures.

In an embodiment of the storage system, the transfer rail grid may comprise an interface connectable to a third-party storage, production and/or distribution system. The transfer rail grid may be integrable with a third-party storage, production and distribution system such that storage containers, packaging boxes and/or pallets can be transported between the storage system of the first aspect and the third-party storage, production and/or distribution system. The transfer rail grid may be connectable to a third-party storage, production and distribution system such as production facility, a storage grid, assembling facility, reception or shipping location, etc. The connection may be by means of a connectable rail system or a conveyor system comprising conveyors employed to transport the storage containers, packaging boxes and/or pallets between the transfer rail grid and the third-party storage, production and/or distribution system.

In an embodiment of the storage system, the second position may be at a production facility, e.g. an assembly line or assembly station.

In an embodiment of the storage system, the transfer rail grid may comprise at least one transfer vehicle path arranged external to the storage grid structure and interconnecting the first and second openings of the transfer section arranged at separate external sides (or side sections) of the storage grid structure, e.g. such that the transfer section extends between two opposite sides/walls of the storage grid.

In an embodiment of the storage system, the at least one transfer column may be spaced from the horizontal periphery of the storage grid structure, i.e. the at least one transfer column is separated from the periphery of the storage grid structure by at least one column, e.g. a storage column.

In an embodiment of the storage system, the transfer section may extend to a section or part of, or a position within, the storage grid structure wherein the horizontal distance to any external side of the storage grid corresponds to the width of at least five adjacent grid columns or wherein the horizontal distance to the external side of the storage grid from which the transfer section extends corresponds to the width of at least five adjacent grid columns.

In an embodiment of the storage system, the length of the transfer section may be equal to at least half the length of an external side of the storage grid structure, which external side extends in the same direction as the transfer section.

In an embodiment of the storage system, the transfer section may comprise, or may be defined by, multiple horizontal ceiling profiles, vertical support profiles arranged at opposite ends of at least some of the ceiling profiles, e.g. at the opposite ends of at least some of the ceiling profiles, and the transfer rails, or a section of the transfer rail grid, arranged within the storage grid. The ceiling and support profiles may also be termed ceiling and support beams.

In an embodiment of the storage system, the multiple horizontal ceiling profiles may provide, or may be arranged as, a horizontal support grid.

In an embodiment of the storage system, the height of the transfer section may be defined by the distance between a lowermost surface of a ceiling profile and an upper surface of an opposing transfer rail of the transfer rail grid. In other words, the height is defined by the distance between a ceiling profile and an opposing transfer rail. Consequently, a container transfer vehicle carrying a storage container has a height being lower than the height of the transfer section when arranged on the transfer rail grid.

In an embodiment of the storage system, the width of the transfer section may be defined by the distance between the two support profiles connected at opposite ends of a common ceiling profile.

In an embodiment of the storage system, the multiple transfer columns may be defined by vertical column profiles extending from the top rail grid to the ceiling profiles and/or the support grid.

In an embodiment, the storage system may comprise multiple storage columns arranged above the transfer section, which columns comprise stopper elements, such that storage containers arranged in the storage columns are prevented from entering the transfer section.

In an embodiment, the storage system may comprise an operator access passage arranged adjacent to at least one side of the transfer section. The access passage may be arranged below multiple storage columns arranged adjacent to at least one side of the transfer section, which storage columns comprise stopper elements, such that storage containers arranged in the storage columns are prevented from entering the access passage. The access passage may run adjacent to the transfer section, such that an operator or service person may access a container transfer vehicle arranged on the transfer rail grid or vehicle path(s) within the transfer section. The stopper elements may be arranged at a suitable height for allowing an operator to walk beneath any storage container accommodated in the row of storage columns adjacent to the transfer section.

In an embodiment, the transfer of the storage container between the top rail grid and the container carrier of one of the container transfer vehicles may be performed by a dedicated container lift arranged in the transfer column. However, the transfer of the storage container between the top rail grid and the container carrier of one of the container transfer vehicles is preferably performed by any of the container handling vehicles, i.e. by use of a lifting device of any of the container handling vehicles.

The at least one transfer column is preferably arranged such that a container handling vehicle may lower a storage container from the top rail grid, via the transfer column, to a container transfer vehicle arranged below the transfer column. Consequently, the lower end of the transfer column has an opening allowing the storage container to enter the transfer section from above.

In an embodiment of the storage system, the transfer section may extend to an internal section of the storage grid structure, wherein the horizontal distance to an external side, side wall or section of the storage grid corresponds to the width of at least five, at least six or at least seven adjacent grid columns. In other words, the transfer section may extend to a position below a transfer column being separated from any external side section of the storage grid structure. The transfer column may for example be separated from any external side section of the storage grid structure by at least five, at least six or at least seven adjacently arranged storage columns, or may be arranged proximate to a center of the storage grid structure. Having a transfer section extending a sufficient length within the storage grid structure ensures that the distances between the storage columns and the transfer columns are minimized. Consequently, the container handling vehicles will spend less time travelling back and forth to the transfer columns and the operation of the system is optimized.

The container carrier may be arranged to receive a container from above and hence carry that container above the container transfer vehicle, e.g. carry the container at a level above a vehicle body of the container transfer vehicle. The storage system may be arranged such that in use containers are passed directly between container handling vehicles and container transfer vehicles.

The container transfer vehicle and/or the transport vehicle may comprise a weighing mechanism in order to measure the weight of a storage container, packaging box and/or pallet. The weighing mechanism may for example be based on a commercially available electronic weighing scale. The weighing mechanism may provide information concerning the contents inside each storage container, packaging box and/or pallet, such as the total weight, the number of units, the internal weight distribution and/or the location within the storage grid the storage container, packaging box and/or pallet should be placed.

The first aspect of the invention may alternatively be defined as a storage system comprising a storage grid structure and multiple container handling vehicles, the storage grid structure comprises vertical column profiles defining multiple storage columns, in which storage containers can be stored one on top of another in vertical stacks, and at least one transfer column, the column profiles are interconnected at their upper ends by top rails forming a horizontal top rail grid upon which the container handling vehicles may move in two perpendicular directions, the container handling vehicles are able to retrieve storage containers from, and store storage containers in, the storage columns, and transport the storage containers on the storage grid structure,.

In a second aspect, which is an example useful for understanding the invention to which this European patent relates, it provides a transport vehicle for a storage system according to any of the preceding claims, comprising a carrier platform and at least two adjacently connected wheel base units, the carrier platform supported upon the wheel base units, and each wheel base unit features a wheel arrangement having a first set of wheels enabling lateral movement of the transport vehicle in a first direction upon a rail grid and a second set of wheels enabling lateral movement of the transport vehicle in a second direction being perpendicular to the first direction.

In other words, each wheel base unit features a wheel arrangement having a first set of wheels enabling lateral movement of the wheel base unit, and consequently the transport vehicle, in a first direction upon a rail grid and a second set of wheels enabling lateral movement in a second direction being perpendicular to the first direction.

In an embodiment, each wheel arrangement may comprise eight wheels and each set of wheels may comprise four wheels.

In an embodiment, each set of wheels may comprise two pairs of wheels arranged on opposite sides of the wheel base unit.

In an embodiment of the transport vehicle, one or both sets of wheels in the wheel arrangement can be lifted and lowered, so that the first set of wheels and/or the second set of wheels can be engaged with a respective set of rails of the rail grid at any one time.

The wheels may be arranged such that the first set of wheels may be in contact with a first pair of opposite rails of a grid cell of the rail grid, while the second set of wheels are arranged above a second pair of opposite rails of the same grid cell, or vice versa.

In an embodiment of the transport vehicle, the rail grid upon which the transport vehicle may move features grid cells having a horizontal area within which a horizontal periphery of the wheel base unit may fit or be accommodated. In other words, the wheel base unit has a horizontal periphery fitting within the horizontal area of a grid cell of the rail grid.

In an embodiment of the transport vehicle, the carrier platform may comprise a conveyor assembly able to move an item arranged on the carrier platform in a horizontal direction off the transport vehicle. In other words, the conveyor assembly is arranged such that an item arranged on the carrier platform may be transferred off the carrier platform in a horizontal direction.

In a third aspect, the present invention provides a method of transporting items in a storage system according to the first aspect, comprising the steps of:.

In a fourth aspect, the present invention provides a method of transporting items into a storage system according to the first aspect, comprising the steps of:.

The term "transfer section" is in the present application intended to mean a substantially horizontal tunnel/passageway and/or recess in the storage grid structure, having at least one open end or side, i.e. opening, at an external side or wall of the storage grid. The opening allowing a container transfer vehicle to enter/exit the transfer section from a position external to the storage grid structure. Alternatively, the term "transfer section" may be replaced by "transfer section space" or "transfer space".

The present invention is described in detail below by way of example only and with reference to the following drawings:.

Furthermore, even if some of the features are described in relation to the system only, it is apparent that they are valid for the related methods as well, and vice versa.

An embodiment of a storage grid for an automated storage and retrieval system according to the invention is shown in <FIG> and <FIG> and the same storage grid featuring a container handling vehicle <NUM> and a container transfer vehicle <NUM> is shown in <FIG>. The number of storage columns of the grid is scaled down to better illustrate the features of the storage grid. The major part of the storage grid is constructed in the same manner as in the prior art systems shown in <FIG> and <FIG>. That is, the storage grid structure <NUM> comprises vertical column profiles <NUM> defining multiple storage columns <NUM>, in which storage containers <NUM> can be stored one on top of another in vertical stacks <NUM>. The column profiles <NUM> are interconnected at their top ends by top rails <NUM>,<NUM> forming a horizontal rail grid <NUM> (hereinafter termed the top rail grid) upon which container handling vehicles <NUM>,<NUM> may move in two perpendicular directions.

In addition to the storage columns <NUM>, the storage grid structure of the storage system comprises multiple transfer columns <NUM>,<NUM> through which storage containers may be transferred between the top rail grid <NUM> (i.e. the top level of the grid) and a transfer section <NUM> (or tunnel/passageway) extending within the storage grid structure at a level below the top rail grid. The transfer section extends from an opening in an external side of the grid structure <NUM> and below the multiple transfer columns <NUM>,<NUM>. In an advantageous embodiment, especially in connection with large storage grids, the transfer section may extend to a substantially central position of the storage grid, and even pass all the way through the storage grid via a substantially central section of the storage grid structure <NUM>, to reduce the distance a storage handling vehicle <NUM>,<NUM> must travel to reach a transfer column.

The transfer section <NUM> is defined or constructed by multiple horizontal ceiling profiles <NUM>, vertical support profiles <NUM> and a section of a horizontal rail grid <NUM> (hereinafter termed a transfer rail grid). The ceiling profiles <NUM> providing a horizontal support grid <NUM>. The height H of the transfer section <NUM> may be defined by the distance between a lowermost surface of a ceiling profile <NUM> and an upper surface of an opposing rail <NUM>', <NUM>' of the transfer rail grid <NUM>, and the width W of the transfer section is defined by the distance between an inner surface of two support profiles <NUM> connected to a common ceiling profile <NUM>. The multiple transfer columns <NUM>,<NUM> are defined by vertical column profiles extending from the top rail grid to the ceiling profiles <NUM>. The height H of the transfer section <NUM> is sufficient to allow a container transfer vehicle <NUM> to travel within the transfer section <NUM> when carrying a storage container.

The ceiling profiles <NUM>, and/or the support grid <NUM>, are supported by the vertical support profiles <NUM> arranged at the periphery of the transfer section <NUM>.

<FIG> shows a situation in which a storage container <NUM> is being transferred between a container transfer vehicle <NUM> and a container handling vehicle <NUM>.

The transfer rail grid <NUM> in the transfer section <NUM> comprises rails <NUM><NUM>', <NUM>' (i.e. transfer rails), similar to the rails <NUM>,<NUM> (i.e. top rails) of the top rail grid <NUM>, upon which a container transfer vehicle <NUM> (or delivery vehicle) may move in two perpendicular directions. The container transfer vehicle <NUM>, see <FIG> for an embodiment of a suitable transfer vehicle, features a wheel base unit <NUM>, see <FIG>, having a wheel arrangement. The wheel arrangement comprises a first set of wheels 32a enabling movement of the transport vehicle in a first direction and a second set of wheels 32b enabling movement of the transport vehicle in a second direction perpendicular to the first direction, allowing the vehicle to travel upon the transfer rail grid <NUM>. On top of the wheel base unit <NUM> the container transfer vehicle <NUM> features a container carrier <NUM> for accommodating a storage container to be transferred. The disclosed container transfer vehicle <NUM> features a container carrier <NUM> in the form of a deep tray, in which a lower portion of a storage container <NUM> may be accommodated. However, numerous alternative solutions for suitable container carriers are envisaged and the main functional feature of all suitable containers carriers is the ability to receive a storage container being lowered on top of the container carrier and retain the storage container during movement of the container transfer vehicle upon the transfer rail grid <NUM>. Further, the horizontal periphery of the container transfer vehicle <NUM> is preferably such that each of the multiple adjacent transfer columns <NUM>,<NUM> may be used to transfer a storage container <NUM> to a respective container transfer vehicle <NUM> simultaneously. To obtain the latter function, the horizontal periphery of the container transfer vehicle <NUM> fits within the horizontal area defined by one of the grid cells <NUM>' of the transfer rail grid <NUM>. Further, the transfer rails <NUM>',<NUM>' extending in one of the two perpendicular directions are dual-track rails, see below, to allow multiple container transfer vehicles to be arranged adjacently below the multiple adjacent transfer columns <NUM>,<NUM>.

The transfer section <NUM> has a width W providing room for three separate transfer vehicle paths <NUM>, <NUM>', <NUM>" in a longitudinal direction of the transfer section. By having three separate transfer vehicle paths, three transfer vehicles <NUM> may pass each other at the same time. To allow this feature, at least the rails <NUM>'extending in the longitudinal direction of the transfer section are dual-track rails. Suitable dual-track rails are disclosed in for example <CIT> and <CIT>. A dual-track rail <NUM>', <NUM>' comprises two parallel tracks. In other words, three parallel dual-track rails may provide two parallel transfer vehicle paths. The rails <NUM>' arranged in a perpendicular direction relative the rails <NUM>' extending in the longitudinal direction of the transfer section may be single-track rails or dual-track rails. In particular, when the storage grid structure <NUM> comprises multiple adjacent transfer columns <NUM>,<NUM>, it may be advantageous that all rails <NUM><NUM>',<NUM>' in the transfer rail grid <NUM> are dual-track rail as it provides an optimum flexibility for movement of the container transfer vehicles <NUM> to/from the positions below the transfer columns <NUM>,<NUM>. The design of the transfer rails <NUM>',<NUM>'and the wheel arrangement 32a,32b of the container transfer vehicles <NUM> allows the vehicles to change tracks when needed, i.e. the container transfer vehicle <NUM> may move in two perpendicular directions upon the transfer rail grid <NUM>. The wheel arrangement may preferably be similar to the ones described for the prior art container handling vehicles <NUM>,<NUM>.

Depending on the requirements of the storage system (i.e. the size of the storage grid, turnover of storage containers etc.) one or more of the transfer vehicle paths <NUM>, <NUM>', <NUM>"are arranged below an optional number of transfer columns <NUM>,<NUM>. The grid columns <NUM> arranged above the transfer section and not designated as transfer columns may be used as storage columns <NUM>' (see <FIG> and <FIG>). This is achieved by adding stopper elements <NUM> (e.g. brackets fastened to the relevant column profiles) at the lower end of the respective grid columns <NUM> (the stopper elements in the storage columns <NUM>' arranged above the transfer section <NUM> is not visible in the drawings). The stopper elements <NUM> are designed to support a storage container <NUM> being lowered into the respective grid column <NUM> and prevent it from entering the transfer section <NUM> below. In this manner a minimum of potential storage space is lost from the storage grid structure <NUM> due to the transfer section <NUM>. The stopper elements <NUM> may also be used to provide an operator passage <NUM> below a row of storage columns <NUM>' adjacent to the transfer section <NUM>. In this manner, an operator or service person may access a container transfer vehicle <NUM>, for instance in case of a failure preventing the vehicle from exiting the transfer section.

The transfer rail grid <NUM> extends out of the storage grid structure <NUM> and depending on the design and extent of the transfer rail grid <NUM>, the container transfer vehicles <NUM> may be used to transfer storage containers <NUM> between multiple separate storage grid structures, transfer containers from a storage grid to a picking/stocking stations, transfer to dedicated stocking zones, transfer to an assembly line for delivery of parts, etc..

A second embodiment of the storage grid <NUM> for an automated storage and retrieval system according to the invention is shown in <FIG> and <FIG>. In this embodiment, the differentiating feature in view of the embodiment discussed above is that the transfer section <NUM> is arranged along or adjacent an external side section <NUM> of the storage grid <NUM>.

A third embodiment of the storage grid <NUM> for an automated storage and retrieval system according to the invention is shown in <FIG> and <FIG>. The main differentiating feature of the third embodiment in view of the embodiments discussed above is the construction of the support grid <NUM> allowing the container transfer vehicles to exit/enter the transfer section via the longitudinal side of the transfer section.

The preferred arrangement and size of the transfer section <NUM> in any given storage system, as well as the positioning of the transfer columns <NUM>,<NUM>, will depend on the size of the storage grid structure <NUM>, the intended use of the storage system <NUM>, the available space in which the storage system is arranged, the shape/layout of said space, etc. Independent of the specific positioning of the transfer section <NUM> within the storage grid structure, the storage system according to the invention will provide a number of advantages in view of the prior art storage systems, as disclosed throughout the present specification.

A schematic overview of an exemplary layout of an exemplary storage system <NUM> is shown in <FIG> and <FIG>. The exemplary layout illustrates some of the many advantages of the storage system.

The storage system in <FIG> comprises three separate storage grid structures <NUM>, <NUM>', <NUM>". Each of the first and the third storage grid structures <NUM>,<NUM>" features a transfer section <NUM>,<NUM>" extending through the whole respective storage grid structure, i.e. the transfer sections extend from a first opening <NUM> in an external side <NUM> of the storage grid to a second opening <NUM> in an opposite external side <NUM>'. In this manner, a container transfer vehicle <NUM> having received or delivered a storage container <NUM> via any of the multiple transfer columns <NUM>,<NUM> may exit the first <NUM> or the second opening <NUM> of the transfer section <NUM> depending on which pathway to a selected destination is most efficient.

Each of the transfer sections <NUM>,<NUM>',<NUM>" features three transfer vehicle paths <NUM>, <NUM>', <NUM>", see <FIG>. The first vehicle path <NUM> is arranged below multiple adjacent transfer columns <NUM>,<NUM>, through which storage containers <NUM> may be transferred between the top rail grid <NUM> and a container transfer vehicle <NUM>. The second and third vehicle paths <NUM>',<NUM>" are arranged below multiple storage columns <NUM>' and are predominantly used by the container transfer vehicles <NUM> to travel within the transfer section to or from a transfer column <NUM>,<NUM>. The transfer section <NUM>' in the second storage grid <NUM>' does not extend all the way through the storage grid, and a container transfer vehicle <NUM> will always enter and exit the transfer section via the first opening.

The transfer grid <NUM> interconnects the transfer columns <NUM>,<NUM> of the first storage grid <NUM> with transfer columns <NUM>,<NUM> of the second and third storage grid <NUM>', <NUM>", with rail loops/circuits <NUM> (that may for instance be arranged at a picking/stocking station, see <FIG>), with a multi-use transfer grid area <NUM> and any other destination to which the transfer of a storage container is desired. The multi-use transfer grid area <NUM> may for instance be used for stocking large amounts of new items to the storage grid, as temporary parking for transfer vehicles carrying storage containers comprising high-demand items, as a loading area for storage containers to enter the storage grids or may be arranged at a station for loading off pallets and/or packaging boxes with items picked from the storage system. To improve the efficiency of transporting goods/items between a picking/stocking station and the multi-use transfer grid area <NUM>, a dedicated transport vehicle may advantageously be used, see description below of the embodiments shown in <FIG>.

Use of an area or section of the transfer grid <NUM> to accommodate container transfer vehicles <NUM> carrying storage containers <NUM> comprising high-demand items, i.e. a parking section of the transfer grid, provides for a highly efficient method of retrieving items that have a very high picking rate, i.e. that have a particularly high turnover. In prior art systems such high turnover items entail that the specific storage container(s) in which these items are stored is transferred back and forth between a storage column <NUM> and a picking/stocking station more or less continuously. In the inventive storage system, items having a particularly high turnover may permanently (or at least intermediately) be stored in a storage container arranged on a transfer vehicle <NUM>. In this manner, high turnover items may be accessed in a very short time, crowding at the transfer columns are further minimized and unnecessary use of the container handling vehicles <NUM>,<NUM> are avoided.

The schematic overview in <FIG> shows details of the first storage grid <NUM> in <FIG> but may also illustrate an alternative layout of a storage system comprising a single storage grid <NUM>.

<FIG> discloses an embodiment of an inventive storage system having a layout substantially as shown in <FIG>. The storage system features two picking/stocking stations <NUM>, wherein each is arranged such that a container transfer vehicle <NUM> may pass beneath a container access opening <NUM> arranged in the picking/stocking station while moving on the transfer rail grid <NUM>. In other words, the picking/stocking stations <NUM> are arranged such that a container transfer vehicle <NUM> may pass through the picking/stocking station via rail loops <NUM> as shown in <FIG> and <FIG>. Thus, a storage container <NUM> containing an item to be picked (or a storage container into which an item is to be stocked) is first retrieved by a container handling vehicle <NUM>,<NUM> arranged on the top rail grid <NUM>, lowered to a container transfer vehicle <NUM> positioned inside the transfer section <NUM> beneath a suitable transfer column <NUM>,<NUM>, and transported by the container transfer vehicle <NUM> to a picking/stocking station <NUM>, wherein the transfer vehicle stops at a position beneath the container access opening <NUM> to allow an operator to pick the item.

The storage system <NUM> shown in <FIG> and <FIG>, features three laterally separated storage grid structures <NUM>, <NUM>', <NUM>" arranged at the same level. However, it is also envisioned that the storage system may comprise storage grid structures separated in a vertical direction, e.g. stacked on top of each other. When separated in the vertical direction, the transfer rail grid of the storage system may for instance comprise a container transfer vehicle lift for lifting a container transfer vehicle between separate levels of the transfer rail grid, such that a container transfer vehicle may access all areas of the transfer grid.

In the disclosed embodiments, the transfer section <NUM> comprises a section of the transfer rail grid <NUM> featuring three parallel vehicle paths <NUM>,<NUM>',<NUM>" allowing three transfer vehicles <NUM> to pass each other at the same time. However, many of the advantages of the present inventive storage system may also be obtained by use of a transfer section <NUM> comprising at least one vehicle path provided the track is arranged below at least one transfer column <NUM>,<NUM>.

In the disclosed embodiments, the transfer rails <NUM>', <NUM>' of the transfer rail grid <NUM> are dual-track rails identical to the rails <NUM>,<NUM> of the top rail grid. This feature is advantageous in a cost perspective since the number of different parts used in constructing the storage grid structure <NUM> is minimized. Further, it allows for the use of transfer vehicles <NUM> having a wheel arrangement similar to the one used in the container handling vehicles <NUM>,<NUM>, a feature which significantly simplifies the overall system cost. However, the main advantages of the inventive storage system and storage grid structure, e.g. a highly flexible and efficient transfer of storage containers in and out of the storage grid, as well as the avoidance of single point of failures disrupting the operation of the storage system, may also be obtained by embodiments of the invention, wherein the transfer rails of the transfer rail grid <NUM> are different from the rails of the top rail grid <NUM>. An important feature for avoiding a single point of failure is that the container transfer vehicles may pass each other and move in two perpendicular directions upon at least the section of the transfer rail grid arranged in the transfer section. This feature allows the container transfer vehicles to pass around for instance a non-functioning container transfer vehicle which would otherwise have caused an interruption of the storage system operation. The presence of multiple transfer columns may further minimize any risk of a single point of failure disrupting the operation of the storage system.

It is noted that the dimensions of the grid cells <NUM> (see prior art system in <FIG> and <FIG> and the relevant prior art description) of the top rail grid <NUM> are preferably similar or identical to the dimensions of the grid cells <NUM>' (see <FIG>) of the transfer rail grid <NUM>. Having the grid cells of similar dimensions allows for an optimum use of the inventive storage system by allowing adjacent transfer columns to be used simultaneously.

Although the use of dual-track rails <NUM>', <NUM>' in at least one direction of the transfer rail grid <NUM> provides several advantages with regards to for instance space efficiency by allowing container transfer vehicles <NUM> to pass each other at adjacent grid cells <NUM>', an advantageous storage system may also be obtained by having a transfer grid comprising only single-track rails. Use of only single-track rails would, however, require a larger transfer grid to allow container transfer vehicles <NUM> passing each other, as compared to dual-track rails, since such a grid would not allow the container transfer vehicles <NUM> to pass each other on adjacent grid cells <NUM>'. For instance, the dual-track transfer rails <NUM><NUM>',<NUM>' of the transfer grid <NUM> disclosed in <FIG> and <FIG> could be replaced by single-track rails. In that case, two container transfer vehicles <NUM> would still be able to pass each other upon the transfer grid <NUM>, for instance by having one of the container transfer vehicles travelling on vehicle path <NUM> and the other on vehicle path <NUM>".

The automated storage and retrieval system shown in <FIG> is more effective than prior art systems by avoiding or at least reducing congestion of container handling vehicles at the transfer columns. Further advantages of the storage system include increased availability of a transfer column for container handling vehicles operating on top of the storage grid and reduced vulnerability to single point of failure events that may disrupt the operation of the storage system. The storage system is also highly flexible in that the storage container transfer capacity, as well as the purpose/function of the storage container handling system, can easily be increased or modified after installation.

An advantageous transport system for obtaining an efficient transport of items between the picking/supply station <NUM> and an unloading/loading assembly <NUM> is shown in <FIG>. The exemplary unloading/loading assembly <NUM> is shown schematically in <FIG> and features a conveyor for transporting boxes or pallets to and/or from the multi-use transfer grid area <NUM>.

In prior art systems, items to be retrieved from the storage grid <NUM> are picked from the relevant storage containers <NUM> by an operator at a picking/supply station and transferred to packaging boxes <NUM>. The packaging boxes <NUM> are often arranged on a pallet <NUM>, which the operator subsequently transports to the unloading/loading assembly <NUM>. At the unloading/loading assembly <NUM>, the packaging boxes <NUM>/pallet <NUM> are for instance loaded onto a truck for transport to customers, shops etc. The efficiency of the process of picking items, packing them in boxes and transferring them to an unloading/loading station is not optimized. In particular, the process requires that the operator use valuable time in transporting the packaging boxes/pallet from the picking/supply station to the unloading/loading assembly.

To provide an efficient transport of items between the picking/supply station <NUM> and an unloading/loading assembly <NUM>, the disclosed transport system features a transport vehicle <NUM> running on a transfer grid <NUM> extending between the picking/supply station <NUM> and the unloading/loading assembly <NUM>. The transfer grid <NUM> of the transport system may comprise any of the features described above for the transfer grids <NUM> shown in <FIG>.

The transport vehicles shown in <FIG>, as well as <FIG>, features four wheel base units <NUM> providing a wheel arrangement having a first set of wheels 32a enabling movement of the transport vehicle in a first direction and a second set of wheels 32b enabling movement of the transport vehicle in a second direction perpendicular to the first direction upon the transfer grid <NUM>.

A carrier platform <NUM> having a conveyor system <NUM> may be arranged on top of the wheel base units <NUM>, as shown. The carrier platform <NUM> may be sized to support four packaging boxes <NUM> and/or a pallet <NUM>, i.e. the area of the carrier platform is substantially equal to the footprint of four storage containers arranged two by two in such an embodiment. In the disclosed storage system, the storage containers may preferably have a width of <NUM> and a length of <NUM>. The preferred dimensions entail that a carrier platform having an area substantially equal to the footprint of four storage containers arranged two by two may accommodate a EUR <NUM> pallet.

In the exemplary embodiment, the conveyor system <NUM> is made up of multiple rollers <NUM>, but other conveyor systems, such as belt or chain conveyors, may also be used. The conveyor system <NUM> is advantageous in that it allows the packaging boxes and/or pallet arranged on the carrier platform <NUM> to be moved off the transport vehicle onto the conveyor of the unloading/loading assembly <NUM>. However, in alternative embodiments of the transport vehicle, the carrier platform may also be without a conveyor system provided the unloading/loading assembly features a lift device (e.g. a pallet jack) arranged to remove packaging boxes <NUM> or a pallet <NUM> from the carrier platform.

The wheel base units <NUM> of the exemplary transport vehicle <NUM> are similar to the wheel base units <NUM>, see <FIG>, of the transfer vehicles <NUM> described above. Each wheel base unit <NUM> features a first set of wheels 32a enabling movement of the wheel base unit in a first direction and a second set of wheels 32b enabling movement of the wheel base unit in a second direction perpendicular to the first direction upon the transfer grid <NUM>. In the exemplary wheel base unit, the second set of wheels 32b is connected to an arrangement for moving the second set of wheels in a vertical direction relative to the first set of wheels. The arrangement features wheel connecting plates <NUM> on opposite sides of the wheel base unit <NUM> and a displacement arm assembly <NUM> for moving the wheel connecting plates <NUM>, and consequently the second set of wheels, in a vertical direction. Each set of wheels 32a,32b of the wheel base unit comprises two pairs of wheels arranged on opposite sides of the wheel base unit.

In the exemplary embodiment, the wheel base units <NUM> are adjacently connected by multiple connecting profiles <NUM> and the carrier platform <NUM> connected to the connecting profiles. Alternative solutions for connecting the wheel base units are also possible and envisaged herein.

An advantage of having a transport vehicle <NUM> made up of multiple wheel base units <NUM> is that a desired size and transport capacity may easily be achieved by varying the number of wheel base units. A further exemplary transport vehicle <NUM>' having two wheel base units is shown in <FIG>.

A further advantage of having the transport vehicle <NUM> made up of multiple wheel base units <NUM> is that the transport vehicle is not only supported by the wheels along its periphery but also supported and driven by wheels along a centreline of the vehicle. This feature provides a high capacity transport vehicle <NUM> without requiring any further reinforcement of the wheels or drive motors to compensate for the increased load.

The transport system in <FIG> is disclosed with a picking/supply station <NUM> and transfer vehicles <NUM> for transferring storage containers between the storage grid and the picking/supply station. However, the transport system is not dependent on the transfer vehicles <NUM> and a transfer section <NUM> as discussed in connection with <FIG> and may alternatively comprise a prior art picking/supply station arranged to receive storage containers <NUM> directly via a transfer column <NUM>,<NUM> without the use of a transfer vehicle <NUM>. Exemplary prior art picking/supply stations suitable for the present transport system are disclosed in for instance <CIT>. In alternative embodiments, wherein a storage system comprising the transport system does not feature container transfer vehicles <NUM>, the multi-use transfer grid area <NUM> may simply be termed a transfer grid area as it is not used for the various operations requiring the container transfer vehicles.

In addition to providing a highly efficient transport of items from the picking/supply station to the unloading/loading assembly, the disclosed transport system is also highly efficient for restocking the storage system with new items brought to the storage system facility on pallets and/or in packaging boxes. The transport system may advantageously also be used for loading new storage containers into the storage grid structure and retrieving used storage containers (e.g. worn out storage containers to be replaced) from the storage grid structure.

Claim 1:
A storage system (<NUM>) comprising a storage grid structure (<NUM>) having a top rail grid upon which container handling vehicles (<NUM>,<NUM>) work to store and retrieve storage containers (<NUM>) in and from storage columns (<NUM>) beneath the top rail grid, a picking/stocking station (<NUM>) for picking/stocking items between a storage container (<NUM>) and a packaging box (<NUM>), and an unloading/loading assembly (<NUM>) for unloading/loading packaging boxes containing such items, wherein the picking/supply station (<NUM>) is operatively connected to a transfer column (<NUM>,<NUM>) of the storage grid structure (<NUM>), such that a storage container (<NUM>) may be transferred between the picking/stocking station (<NUM>) and the storage columns (<NUM>), characterised in that the storage system comprises multiple transfer rails (<NUM>',<NUM>') forming a horizontal transfer rail grid (<NUM>) arranged at a level below the top rail grid, at least one transport vehicle (<NUM>) operating on the transfer rail grid, wherein the transport vehicle (<NUM>) is arranged to move upon the transfer rail grid (<NUM>) in two perpendicular directions and comprises a carrier platform (<NUM>), and wherein the transfer rail grid is arranged to allow access for the transport vehicle (<NUM>) to transport one or more packaging boxes at a time between the picking/stocking station and the unloading/loading assembly (<NUM>).