A method, a system and an aisle cart

Abstract

A method for storing an item (2) at a storage position (16) in a rack (10), the rack (10) comprising: an aisle (20) extending in a first direction (11 ); and a plurality of rows (30), each row (30) extending in a second direction (12) from a respective entrance (35) at the aisle (20), the storage position (16) being a position, for storing the item (2), in a designated row (30) of the plurality of rows (30); the method using an aisle cart (40) and a row cart (60) for transporting the item (2) in the rack (10), the aisle cart (40) comprising at least one wheel (46) for moving the aisle cart (40) along the aisle (20) and the row cart (60) comprising at least one wheel (66) for moving the row cart (60) along the rows (30); the method comprising: transporting the row cart (60) and the item (2) along the aisle (20) using the aisle cart (40), the aisle cart (40) comprising a platform (42) supporting the at least one wheel (66) of the row cart (60) while the aisle cart (40) transports the row cart (60); stopping the aisle cart (40) at the entrance (35) of the designated row (30); displacing the platform (42), relative to the at least one wheel (46) of the aisle cart (40), in the second direction (12) such that a gap between the platform (42) and the entrance (35) of the designated row (30) is reduced; transferring, by the row cart (60), the item (2) into the designated row (30), wherein the at least one wheel (66) of the row cart (60) crosses the reduced gap; transporting, by the row cart (60), the item (2) along the designated row (30); placing, by the row cart (60), the item (2) at the storage position (16) in the designated row (30).

Description

[0001] A METHOD, A SYSTEM AND AN AISLE CART

[0002] TECHNICAL FIELD

[0003] The present inventive concept relates, in general, to storage of items in a rack.

[0004] BACKGROUND

[0005] Automated storage systems are often used in warehouses and distribution facilities. Such a system may comprise a rack, wherein automated vehicles transport items to and from their storage positions in the rack. The rack often comprises several stones, wherein each story comprises aisles and rows. For each aisle, there are generally a plurality of rows extending from the aisle, wherein the items are stored in the rows.

[0006] There are many types of automated vehicles that can be used to transport items within the rack. In some cases, aisle carts and row carts are used. The aisle cart transports the row cart and the item to the entrance of a row. The row cart then leaves the aisle cart and carries the item into the row and places the item at the storage position in the row.

[0007] SUMMARY

[0008] It is an objective of the present inventive concept to enable fast transport of an item in a rack, by an aisle cart and a row cart. It is a further objective to prevent damages to the item and / or to the aisle cart and / or to the row cart and / or to the rack, during transport. It is a further objective to enable a simple and / or low cost aisle cart. It is a further objective to enable a simple and / or low cost row cart. It is a further objective to enable a simple and / or low cost rack.

[0009] These and other objectives of the inventive concept are at least partly met by the invention as defined in the independent claims. Preferred embodiments are set out in the dependent claims. According to a first aspect there is provided a method for storing an item at a storage position in a rack, the rack comprising: an aisle extending in a first direction; and a plurality of rows, each row extending in a second direction from a respective entrance at the aisle, the storage position being a position, for storing the item, in a designated row of the plurality of rows; the method using an aisle cart and a row cart for transporting the item in the rack, the aisle cart comprising at least one wheel for moving the aisle cart along the aisle and the row cart comprising at least one wheel for moving the row cart along the rows; the method comprising: transporting the row cart and the item along the aisle using the aisle cart, the aisle cart comprising a platform supporting the at least one wheel of the row cart while the aisle cart transports the row cart; stopping the aisle cart at the entrance of the designated row; displacing the platform, relative to the at least one wheel of the aisle cart, in the second direction such that a gap between the platform and the entrance of the designated row is reduced; transferring, by the row cart, the item into the designated row, wherein the at least one wheel of the row cart crosses the reduced gap; transporting, by the row cart, the item along the designated row; placing, by the row cart, the item at the storage position in the designated row.

[0010] The item may be a pallet, with or without goods. Alternatively, the item may be any form of goods, crate or box.

[0011] The aisle may comprise a track for the at least one wheel of the aisle cart to run on. The aisle cart may comprise a set of wheels, e.g. four wheels, e.g. a left pair of wheels and a right pair of wheels. The track of the aisle may comprise a pair of rails, e.g. a left rail for the left pair of wheels of the aisle cart to run on and a right rail for the right pair of wheels of the aisle cart to run on.

[0012] Similarly, each row may comprise a track for the at least one wheel of the row cart to run on. The row cart may comprise a set of wheels, e.g. four wheels, e.g. a left pair of wheels and a right pair of wheels. The track of the row may comprise a pair of rails, e.g. a left rail for the left pair of wheels of the row cart to run on and a right rail for the right pair of wheels of the row cart to run on. Both the left and right rail may thus comprise a rolling surface for the wheels of the row cart to roll on. Additionally, the left and right rail may comprise a support surface for the items to be placed on. The support surface of a rail may be arranged above the rolling surface of said rail.

[0013] The first direction, in which the aisle extends, may be perpendicular to the second direction, in which the rows extend. There may be rows extending from the aisle both on the left and right side of the aisle.

[0014] The designated row may be any one of the plurality of rows in which the item is intended to be stored.

[0015] The rack may further comprise at least one loading position where the aisle cart may collect the item. The aisle cart may approach the loading position and collect the item by pulling the item onto the aisle cart, e.g. by using a belt conveyor of the aisle cart. The loading position may be a position at the edge of the rack. The loading position may be an elevator configured to transport the item to a designated story of the rack. The loading position may be a buffer conveyor, e.g. a buffer conveyor at a designated story of the rack, where items are waiting for further transport to their respective designated storage position.

[0016] Thus, the method may be applicable when moving the item from the loading position, via the aisle and the designated row, to the storage position. However, it should be understood that the method is also applicable when moving the item from a first storage position in a first row to a second storage position in a second row, via the aisle. Thus, the method is applicable when rearranging items to new storage positions within the rack. Herein, storing an item at a storage position in a rack refers to any kind of transport of the item to the storage position.

[0017] When the aisle cart transports the row cart and the item along the aisle, the row cart may stand on the platform under the item. When the aisle cart transports the row cart and the item along the aisle, the item may stand on the belt conveyor.

[0018] Before the row cart transfers the item into the designated row, the row cart may lift the item using a lifting device. Thus, the item may be lifted up from the belt conveyor of the aisle cart. The lifting device may be configured to lift the item by lowering the wheels of the row cart, e.g. lowering the wheels of the row cart relative to the chassis of the row cart. In other words, a separation between the wheels of the row cart and the chassis of the row cart may be increased to lift the item. The row cart may place the item at the storage position in the designated row by lowering the item using the lifting device. The lifting device may be configured to lower the item by raising the wheels of the row cart, e.g. raising the wheels of the row cart relative to the chassis of the row cart. In other words, a separation between the wheels of the row cart and the chassis of the row cart may be reduced to lower the item. The row cart may place the item on the support surfaces of the left and right rail of the designated row at the storage position in the designated row.

[0019] The platform of the aisle cart may be arranged on the aisle cart such that when the aisle cart is standing in the aisle in front of the entrance of the designated row, the platform is at the same height as the track of the row. However, it may also be possible to use a platform which is above or below the track of the row. The platform may be at the same height as the rolling surface of one of the rails of the designated row.

[0020] The gap between the platform and the entrance of the designated row may be a gap in the second direction. The gap between the platform and the entrance of the designated row may be a gap between the platform and the track of the designated row, e.g. between the platform and a rolling surface of a rail of the designated row. The gap between the platform and the entrance of the designated row may be a gap which the at least one wheel of the row cart rolls across when the row cart moves from the platform onto the track of the designated row.

[0021] Displacing the platform may be done after, during, or before stopping the aisle cart. As a first example, the displacement of the platform may begin when the aisle cart is standing still at the entrance of the designated row. As a second example, the displacement of the platform may begin after the aisle cart has begun to reduce its speed during the approach of the designated row. As a third example, the displacement of the platform may begin when the aisle cart is between the entrance of the designated row and the entrance of the closest adjacent row, e.g. before the aisle cart has begun to reduce its speed. The third example may facilitate faster transport than the first and second example. The first example may facilitate safer transport than the second and third example.

[0022] It is a realization that displacing the platform, relative to the at least one wheel of the aisle cart provides several advantages.

[0023] When the platform is displaceable it is possible to, during transport in the aisle, have a large gap between the platform of the aisle cart and the entrances of the rows that the aisle cart passes. When the aisle cart has arrived at the designated row, the platform may be displaced to reduce the gap between the platform and the entrance and thereby facilitate the transfer of the row cart and the item into the designated row.

[0024] Thus, while the aisle cart is moving along the aisle towards the designated row, the platform may be at a safe distance from the entrances of the other rows that the aisle cart passes. Thus, there may be little risk of damage to the aisle cart, row cart or item. Such damage may be caused by the platform, or anything that the platform supports (such as the row cart on top of the platform or the item on top of the row cart), bumping in to any element associated with the entrances of the passed row. Elements associated with the entrances of the rows may be: the tracks of the rows e.g. the rails of the rows, beams or posts for supporting the track of the aisle or the tracks of the passed rows, beams or posts for supporting the aisle or rows on the story above.

[0025] When the row cart moves from the aisle cart into the designated row across the reduced gap there may be little risk that a wheel of the row cart gets stuck in the gap, since the gap is reduced. Further, there may be little risk of damage to the row cart. Such damage may be caused by the wheel dropping into the gap and hitting the edge of the rail of the row. For example, the risk of damage to the wheel itself, to the wheel axle, or to the wheel suspension may be reduced. Further, the reduced gap may lessen the risk of bumps that may displace the item on the row cart and thereby lessen the risk of the displaced item knocking into beams or posts.

[0026] The method enables fast transport of the item.

[0027] The method facilitates fast movement of the aisle cart in the aisle. When the risk of the aisle cart and / or row cart and / or item bumping into anything is low, the risk of damage is low and higher speeds may be thereby be acceptable. Further, high speeds of the aisle cart may cause movements of the row cart standing on top of the aisle cart and / or movements of the item standing on top of the row cart. For example, loads may wobble or shift due to acceleration or deceleration. Such movements may be acceptable when there is a large gap between the platform of the aisle cart and the entrances of the rows that the aisle cart passes.

[0028] The aisle cart may move at a speed of at least 0.3 m / s along the aisle. For example, the aisle cart may move at a speed of at least 1 .5 m / s, or at least 3 m / s, or at least 5 m / s, along the aisle. The above speed limits may be applicable when the aisle cart is transporting the row cart and the item, when the aisle cart is transporting the row cart, or when the aisle cart is moving without a row cart.

[0029] The method facilitates fast movement of the row cart when the row cart enters the designated row. A high speed may be possible when the wheel runs smoothly across a small gap. Further, when the risk of a wheel of the row cart getting stuck, or dropping into the gap and hitting the edge of the rail, is low, the risk of damage is low and higher speeds may be acceptable.

[0030] The method enables a simple construction of the row cart. For example, fewer wheels may be needed than in a case where a non- displaceable platform is used. If a non-displaceable platform is used, the gap may be large, at least if the aisle cart is intended to run at high speed. Thus, many wheels may be needed to cross the gap smoothly. For example, eight or more wheels may be needed.

[0031] The method enables a cost effective system for storing items. Due to the fast transport of the items, more items may be transported to their respective storage positions per time unit, which saves cost. Further, few damages to the aisle cart, row cart and items also saves cost. Further, a simple construction of the row cart also saves cost.

[0032] In one implementation of the method, the aisle cart comprises a belt conveyor for pulling the item on or off the aisle cart and supporting the item while the aisle cart transports the item, the belt conveyor being attached to the platform and configured to be displaced relative to the at least one wheel of the aisle cart together with the platform; a motor for driving the belt conveyor, the motor being immovably attached to a chassis of the aisle cart such that the motor is prevented from being displaced relative to the at least one wheel of the aisle cart; the method further comprising: driving the belt conveyor by the motor, such that the item supported by the belt conveyor is moved by the belt conveyor in the second direction, wherein the belt conveyor belt is driven while the platform is displaced relative to the at least one wheel of the aisle cart; or declutching the belt conveyor from the motor before or while the platform is displaced relative to the at least one wheel of the aisle cart.

[0033] It may be advantageous to have the belt conveyor attached to the platform and configured to be displaced relative to the at least one wheel of the aisle cart together with the platform. This may enable a simple construction of the aisle cart. Further, a belt conveyor which can be displaced together with the platform may facilitate fast and / or safe loading of the item onto the aisle cart, e.g. at the loading position. Thus, the aisle cart may reach further by the displaceable belt conveyor. It is further advantageous to have the motor for driving the belt conveyor immovably attached to the chassis of the aisle cart. There may be more room for the motor if it is attached to the chassis than if it is attached to the displaceable platform.

[0034] The belt conveyor may be a chain belt conveyor comprising an endless chain running between a first and second sprocket. Between the first and second sprocket, a drive sprocket may be arranged to drive an upper or lower part of the endless chain. The motor may drive the drive sprocket which in turn drives the chain of the chain belt conveyor. The chain belt conveyor may be arranged such that a clockwise movement of the chain may moves the item in the second direction and an anti-clockwise movement of the chain may move the item in the opposite direction. Thus, an item may be pulled on or off the aisle cart by the chain belt conveyor. However, movements of the item relative to the platform during displacement of the platform may be unwanted.

[0035] If the belt conveyor is driven or declutched during displacement of the platform such unwanted movements may be prevented. To exemplify, consider the situation where the chain belt conveyor is not driven or declutched during displacement of the platform in the second direction. In this situation, when the chain belt conveyor is displaced together with the platform, the drive sprocket will pull on the chain and force it to move anticlockwise. Thus, even if the chain belt conveyor is displaced in the second direction, the item may remain at the same place relative to the chassis of the aisle cart and possibly fall off the back of the chain belt conveyor. As mentioned, this may be prevented by driving the belt conveyor by the motor, such that the item supported by the belt conveyor is moved by the belt conveyor in the second direction (in this case driving the belt conveyor clockwise) or declutching the belt conveyor.

[0036] According to a second aspect there is provided a system for storing an item at a storage position, the system comprising a rack comprising: an aisle extending in a first direction; and a plurality of rows, each row extending in a second direction from a respective entrance at the aisle; wherein the storage position is a position, for storing the item, in a designated row of the plurality of rows; an aisle cart and a row cart for transporting the item in the rack, the aisle cart comprising at least one wheel for moving the aisle cart along the aisle and the row cart comprising at least one wheel for moving the row cart along the rows; the aisle cart being a cart for transporting the row cart and the item along the aisle, the aisle cart comprising a platform, the platform being configured to support the at least one wheel of the row cart while the aisle cart transports the row cart, the platform being displaceable relative to the at least one wheel of the aisle cart; the row cart being a cart for transporting the item along the designated row; wherein the aisle cart is configured to, at the entrance of the designated row, displace the platform relative to the at least one wheel of the aisle cart in the second direction such that a gap between the platform and the entrance of the designated row is reduced.

[0037] A system according to the second aspect may have the same advantages, or similar advantages, as the advantages described in conjunction with the first aspect.

[0038] There may be configurations of the system, wherein the designated row comprises a rail for the wheel of the row cart to travel on, the rail extending in the second direction; wherein the gap between the platform and the entrance of the designated row is a gap between a first edge of the rail of the designated row and a first edge of the platform of the aisle cart; wherein an angle of the first edge of the rail is an angle between the first edge of the rail and the second direction; wherein an angle of the first edge of the platform is an angle between the first edge of the platform and the second direction when the aisle cart is in the aisle; and wherein both the angle of the first edge of the rail and the angle of the first edge of the platform are larger or smaller than 90°.

[0039] Both the angle of the first edge of the rail and the angle of the first edge of the platform may be larger than 90°. Both the angle of the first edge of the rail and the angle of the first edge of the platform may be smaller than 90°. The first edge of the rail and the first edge of the platform may be substantially parallel or at least parallel within 15°.

[0040] The first edge of the rail may be an edge of the rolling surface of the rail.

[0041] It is a realization that the wheel of the row cart may roll easily over the first edge of the platform and the first edge of the rail when the angles of said edges are larger or smaller than 90°. Thus, the wheel may not roll in a direction perpendicular to the edges and may thereby be prevented from dropping into the gap.

[0042] If the platform is not displaceable, the most convenient choice may be to have both the angle of the first edge of the rail and the angle of the first edge of the platform to be 90°. However, this is not necessarily the case when the platform is displaceable.

[0043] When the platform is displaced in the second direction and both the angle of the first edge of the rail and the angle of the first edge of the platform are larger or smaller than 90°, said edges may interlock and prevent the aisle cart from moving either forward or backwards in the aisle. However, when it is time for the aisle cart to continue moving along the aisle, the platform may be retracted such that the first edge of the rail and the first edge of the platform no longer interlocks.

[0044] The system may be configured such that both the angle of the first edge of the rail and the angle of the first edge of the platform deviates from 90° by at least 10°. The system may be configured such that both the angle of the first edge of the rail and the angle of the first edge of the platform deviates from 90° by 30°-60°.

[0045] The aisle cart may be configured to, at the entrance of the designated row, displace the platform relative to the at least one wheel of the aisle cart by at least 20 mm. For example, the aisle cart may be configured to, at the entrance of the designated row, displace the platform relative to the at least one wheel of the aisle cart by at least 40 mm, 60 mm, or 80 mm. A preferred displacement is 85 mm but shorter or longer displacements may also be advantageous.

[0046] The system may be configured such that the gap between the platform and the entrance of the designated row is less than 50 mm, when the aisle cart, at the entrance of the designated row, has displaced the platform relative to the at least one wheel of the aisle cart. When the gap is smaller than 50 mm it may be sufficient to use four wheels for the row cart. When the gap is larger than 50 mm more than four wheels may be needed for the row cart, e.g. eight wheels. It may be advantageous with even smaller gaps. Such smaller gaps may facilitate faster and safer transfer of the row cart into the designated row. The system may be configured such that the gap between the platform and the entrance of the designated row is less than 30 mm, or less than 20 mm, when the aisle cart, at the entrance of the designated row, has displaced the platform relative to the at least one wheel of the aisle cart. It is preferred that the system is configured such that the gap between the platform and the entrance of the designated row is 5 mm, when the aisle cart, at the entrance of the designated row, has displaced the platform relative to the at least one wheel of the aisle cart.

[0047] The platform may be displaceable both forwards and backwards in the second direction from a first position of the platform, the first position of the platform being a position of the platform relative to the at least one wheel of the aisle cart during transport of the row cart and the item along the aisle.

[0048] Thus, the aisle cart may deliver the row cart either to a row on the right hand side of the aisle (e.g. by displacing the platform forwards) or to a row on the left hand side of the aisle (e.g. by displacing the platform backwards).

[0049] The aisle cart may comprise two platforms, the two platforms being a first and a second platform, the first platform being configured to support a left side wheel of the row cart and the second platform being configured to support a right side wheel of the row cart, wherein the first and second platform are separated by an open space; wherein both the first and second platform are displaceable relative to the at least one wheel of the aisle cart; and wherein the aisle cart is configured to, at the entrance of the designated row, displace both the first and second platform relative to the at least one wheel of the aisle cart in the second direction.

[0050] Thus, the first and second platforms may be rails. The first and second platforms may be rails corresponding to the rolling surfaces of the respective left and right rail of the rows. The first and second platform may be arranged such that part of the row cart, e.g. the body of the row cart, fits in the open space between the first and second platform. This may facilitate a low center of gravity of the row cart relative to the first and second platforms when the wheels of the row cart are supported by the first and second platform. For example, the center of gravity of the row cart may be below the first and second platform. A low center of gravity may facilitate stable transport of the row cart. Further, the open space between the first and second platform may make the first and second platform compatible with the left and right rail of the rows. The left and right rail of the rows may also have an open space between them which fits part of the row cart.

[0051] As previously discussed, the aisle cart may further comprise a belt conveyor for pulling the item onto the aisle cart and supporting the item while the aisle cart transports the item, the belt conveyor being attached to the platform and configured to be displaced relative to the at least one wheel of the aisle cart together with the platform.

[0052] The aisle cart may further comprise a motor for driving the belt conveyor, the motor being immovably attached to a chassis of the aisle cart such that the motor is prevented from being displaced relative to the at least one wheel of the aisle cart, wherein the aisle cart is configured to: drive the belt conveyor by the motor while the platform is displaced relative to the at least one wheel of the aisle cart; or declutch the belt conveyor from the motor before or while the platform is displaced relative to the at least one wheel of the aisle cart.

[0053] The aisle cart may comprise a blocking element, the blocking element being a movable element which: in a blocking position, blocks the row cart from leaving the platform; and in an unblocking position, unblocks the row cart from leaving the platform; wherein the aisle cart is configured to move the blocking element from the blocking position to the unblocking position such that the blocking element arrives at the unblocking position after the platform has started displacing relative to the at least one wheel of the aisle cart.

[0054] The blocking element may advantageously prevent the row cart from leaving the aisle cart too early, e.g. leaving the aisle cart before the gap has been sufficiently reduced.

[0055] The aisle cart may be configured such that the blocking element arrives at the unblocking position when the gap is smaller than 50 mm, such as smaller than 30 mm or smaller than 20 mm. Such limits may be considered to be a sufficient reduction for safe transfer of the row cart into the designated row, as discussed above. The row cart may still be configured to wait until the displacement of the platform is finished. However, the blocking element may provide an additional safety mechanism.

[0056] The aisle cart may be configured such that the blocking element arrives at the unblocking position when the platform has been displaced at least 50% of its travel length. For example, consider the situation where the system is configured such that the first edge of the platform is 90 mm from the first edge of the rail of the designated row, when the aisle cart is standing at the entrance of the designated row. The platform may have a travel length of 85 mm, i.e. it may be displaced 85 mm towards the rail of the designated row, such that when the displacement is finished the gap is 5 mm. The aisle cart may be configured such that the blocking element arrives at the unblocking position when the gap is smaller than 50 mm, i.e. when the platform has been displaced 40 mm, i.e. when the platform has been displaced 47% of its travel length.

[0057] The blocking element may be a lever pivotably attached to the platform. The blocking position may be a position in the travel path of the row cart.

[0058] The aisle cart may be configured to mechanically trigger the movement of the blocking element from the blocking position to the unblocking position by the platform being displaced.

[0059] A mechanically triggered movement of the blocking element may have several advantages, e.g. advantages over an electronically triggered movement of the blocking element. A mechanically triggered movement of the blocking element may be easy and / or cheap to implement. A mechanically triggered movement of the blocking element may be safe. For example, updates of the software of the aisle cart may not affect the function of the blocking element.

[0060] According to a third aspect there is provided an aisle cart for transporting a row cart and an item along an aisle of a rack, the aisle cart being movable along the aisle in a first direction, the aisle cart comprising: at least one wheel for moving the aisle cart along the aisle; and a platform configured to support at least one wheel of the row cart while the aisle cart transports the row cart, the platform being displaceable relative to the at least one wheel of the aisle cart; wherein the aisle cart is configured to displace the platform relative to the at least one wheel of the aisle cart in a second direction when the aisle cart is at an entrance of a designated row, wherein the designated row is a row extending in the second direction from the entrance of the row, the entrance of the row being an entrance at the aisle.

[0061] An aisle cart according to the third aspect may have the same advantages, or similar advantages, as the advantages described in conjunction with the first and second aspect.

[0062] BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The above, as well as additional objects, features and advantages of the present inventive concept, will be better understood through the following illustrative and non-limiting detailed description, with reference to the appended drawings. In the drawings like reference numerals will be used for like elements unless stated otherwise.

[0064] Fig. 1 illustrates a system for storing an item.

[0065] Fig. 2a-c illustrate an aisle cart, a row cart, aisle rail, and row rail.

[0066] Fig. 3 illustrates an aisle cart, a row cart, aisle rail, and row rail.

[0067] Fig. 4 illustrates an aisle cart.

[0068] Fig. 5 illustrates an aisle cart.

[0069] Fig. 6a-c illustrate an aisle cart, a row cart, and aisle rail,

[0070] Fig. 7 illustrates an aisle rail and a guide member.

[0071] Fig. 8 illustrates an aisle cart and aisle rail.

[0072] Fig. 9a-b illustrate an aisle rail.

[0073] Fig. 10 illustrates a row cart and row rail.

[0074] Fig. 11 illustrates a row rail.

[0075] Fig. 12 illustrates a bridge rail.

[0076] Fig. 13 illustrates an aisle cart, a row cart, aisle rail, and row rail.

[0077] Fig. 14 illustrates a row rail.

[0078] Fig. 15 illustrates a bridge rail, a row rail, and a platform.

[0079] DETAILED DESCRIPTION

[0080] In cooperation with attached drawings, the technical contents and detailed description of the present invention are described thereinafter according to a preferable embodiment, being not used to limit the claimed scope. This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0081] Fig. 1 illustrates a system 1 for storing an item 2. The system comprises a rack 10, the rack 10 comprises an aisle 20 and a plurality of rows 30. The illustrated rack 10 comprises three stories, each story comprising an aisle 20 and a plurality of rows 30. The aisle 20 extends in a first direction 11 and each row 30 extend in a second direction 12. In the figure, the first direction is the X direction and the second direction is the Y direction. It should be understood that the directions may be denoted differently. For example, in the FEM (European materials handling federation) standard, the direction in which the aisle extends (the first direction 11 ) is referred to as the X direction and the direction in which the rows extends (the second direction 12) is referred to as the Z direction, while the vertical direction is referred to as the Y direction.

[0082] Each row 30 comprises an entrance 35 and a far end 39. The entrance 35 of the row 30 being at the aisle 20 and the far end 39 being at the opposite end of the row 30.

[0083] In Fig. 1 , for clarity, the item 2 is not illustrated. However, the item 2 may be a pallet 3, with or without goods 4. Alternatively, the item 2 may be any form of goods 4, crate or box. The rack 10 of Fig. 1 is suitable to store items 2 in the form of pallets 3, with or without goods 4.

[0084] The system 1 further comprises an aisle cart 40, and a row cart 60. The aisle cart 40 and row cart 60 are configured to transport the item 2 to a storage position 16 in a designated row 30, e.g. from a loading position 14 to the storage position 16. The storage position 16 may be any position along the designated row 30. The designated row 30 may be any row 30 of the plurality of rows 30.

[0085] In the following, the top story of the rack 10 in Fig. 1 will be discussed as an illustrative example. The top story of the rack 10 comprises an aisle 20 and a plurality of rows 30. The aisle 20 extends in the X direction, starting at a loading position 14 at the at the edge of the rack 10. A plurality of rows 30 extend to the left (in the positive Y direction) and to the right (in the negative Y direction) of the aisle 20. Each row 30 has an entrance 35 at the aisle 20. In Fig. 1 , an aisle cart 40 is seen in the aisle 20 of the top story of the rack 10. A row cart 60 is seen in the first row 30 to the right of the top story of the rack 10. As mentioned, the storage position 16 may be any position along the designated row 30, e.g. a position furthest from the entrance 35 of the row 30 which is free to accept the item 2. A storage position 16 is indicated in the last row 30 to the left of the aisle 20 of the top story of the rack 10 in Fig. 1 . Since said row 30 is empty in the figure, the storage position may be at the far end 39 of said row 30.

[0086] The far end 39 of the rows 30 may be arranged to allow the row cart 60 being: received by the row cart 60 being lowered onto the row rail 32; and / or collected by the row cart 60 being lifted off the row rail 32.

[0087] For example, the far end 39 may be open, such that a fork lift or an elevator may deliver the row cart at the far end of the row rail 32. Thus, row carts 32 (e.g. empty row carts 32) may be delivered into (or retrieved from) the rack 10 without having to take the path through the aisle 20. Thus, congestion in the rack 10 may be avoided.

[0088] Further, as illustrated in Fig. 1 , a row 30 may, at the far end 39, be free from horizontal support elements connecting the row rails of the pair of row rails, within a distance from the outermost point of the row rails. This is for example seen at the marked storage position 16. The distance may be 0.5 m or 1 m. Alternatively, the distance may be equal or larger than the length of the row cart (not shown). Thus, a row cart supported from below by e.g. the fork of a forklift may be lifted into the row without the fork being obstructed by a horizontal support element.

[0089] Figs 2a-c illustrate the aisle cart 40 arriving at a designated row 30 and the row cart 60 moving into the designated row 30. Again, for clarity, the item 2 is not illustrated.

[0090] The illustrated aisle 20 comprises a rail 22 (henceforth called aisle rail 22). In the illustrations, the aisle rail 22 is in the form of a hollow beam 50. As illustrated, there may be a pair of aisle rails 22. The aisle cart 40 may comprise a wheel 46 (also called support wheel 46 of the aisle cart 40) for rolling on the aisle rail 22. The aisle cart 40 may comprise two pairs of support wheels 46.

[0091] In Figs 2a-c, there is one row 30 to the left of the aisle 20 and one row 30 to the right of the aisle 20, with a respective entrance 35 at the aisle 20. Each illustrated row 30 comprises a rail 32 (henceforth called row rail 32). As illustrated, each row 30 may comprise a pair of row rails 32. The row cart 60 may comprise a wheel 66 (also called support wheel 66 of the row cart 60) for rolling on the row rail 32. The row cart 60 may comprise two pairs of support wheels 66.

[0092] The illustrated aisle cart 40 comprises a platform 42. The platform 42 is best seen in Fig. 2b and Fig. 2c, and in the insets of Fig. 2a and Fig. 2b. The illustrated platform 42 is configured to support the at least one wheel 66 of the row cart 60 while the aisle cart 40 transports the row cart 60, the platform 42 being displaceable relative to the at least one wheel 46 of the aisle cart 40. As illustrated, the aisle cart 40 may further comprise a belt conveyor 52 for pulling the item 2 onto the aisle cart 40 and supporting the item 2 while the aisle cart 40 transports the item 2, the belt conveyor 52 being attached to the platform 42 and configured to be displaced relative to the at least one wheel 46 of the aisle cart 40 together with the platform 42.

[0093] When the aisle cart 40 transports the row cart 60 and the item 2 along the aisle 20, the row cart 60 may stand on the platform 42 under the item 2. When the aisle cart 40 transports the row cart 60 and the item 2 along the aisle 20, the item 2 may stand on the belt conveyor 52. However, the aisle cart 40 does not necessarily need to comprise a belt conveyor 52. For example, when the aisle cart 40 transports the row cart 60 and the item 2 along the aisle 20, the item 2 may stand on the row cart 60, or on a support surface of the aisle cart 40, instead of on the belt conveyor 52.

[0094] The row cart 60 and the item 2 may be transported along the aisle 20 using the aisle cart 40. The aisle cart 40 may be stopped at the entrance 35 of the designated row 30, this is illustrated in Fig. 2a. The platform 42 may then be displaced, relative to the at least one wheel 46 of the aisle cart 40, in the second direction 12 such that a gap 36 between the platform 42 and the entrance 35 of the designated row 30 is reduced.

[0095] Fig. 2a illustrates a gap 36 between the platform 42 and the entrance 35 of the designated row 30.

[0096] Fig. 2b illustrates the platform 42 of the aisle cart 40 being displaced towards the entrance 35 of the designated row. In the figure, the row cart 60 is not displaced for reasons of clarity, such that the platform 42 is visible. In reality, the row cart 60 standing on the platform 42 would be displaced together with the platform 42. Fig. 2b further shows the gap 36 between the platform 42 and the rolling surface 81 (a.k.a. lower horizontal surface 81) of the row rail 32 being closed. The row cart 60 may then move into the designated row 30 by rolling from the platform 42, across the gap 36, and onto the rolling surface 81 of the row rail 32. This is illustrated in Fig. 2c. Part of the row rail 32 has been cut away for illustrative purposes, such that a wheel 66 of the row cart 60 can be seen rolling on the rolling surface 81 of the row rail 32.

[0097] In Fig. 2c, the row cart 60 is not carrying an item 2. This is for illustrative purposes. However, the row cart 60 may carry an item 2, e.g. resting on-top of the row cart 60. Thus, the row cart 60 may transfer the item 2 into the designated row, when the at least one wheel 66 of the row cart 60 crosses the reduced gap 36.

[0098] Before the row cart 60 transfers the item 2 into the designated row 30, the row cart 60 may lift the item using a lifting device 62. The lifting device 62 may be a raisable platform, e.g. part of the chassis of the row cart 60. Thus, the item 2 may be lifted up, e.g. from the belt conveyor 52, of the aisle cart 60. The lifting device 62 may be configured to lift the item 2 by lowering the wheels 66 of the row cart 60, e.g. lowering the wheels 66 of the row cart 60 relative to the chassis of the row cart 60. In other words, a separation between the wheels 66 of the row cart 60 and the chassis of the row cart 60 may be increased to lift the item 2.

[0099] After the row cart 60 has transferred the item 2 into the designated row 30, the row cart 60 may transport the item 2 along the designated row 30. The row cart 60 may then place the item 2 at the storage position 16 in the designated row 30.

[0100] The inset of Fig. 2a and the inset of Fig. 2b show a top view of the aisle cart 40 at the entrance 35 of the designated row 30 before and after displacing the platform 42, respectively. Thus, the insets of Fig. 2a Fig. 2b illustrate the gap 36 being reduced. The gap 36 in the inset of Fig. 2a may be 85 mm. The gap 36 in the inset of Fig. 2b may be 5 mm.

[0101] The insets of Fig. 2a and Fig. 2b illustrate the gap 36 extending between a first edge 43 of the platform 42 and a first edge 33 of the row rail 32. Further, the insets of Fig. 2a and Fig. 2b illustrate that the first edge 33 of the rail 32 may be arranged at an angle to the second direction 12 and that the first edge 43 of the platform 42 may be arranged at an angle to the second direction 12. The system 1 may be configured such that both the angle of the first edge 33 of the rail 32 and the angle of the first edge 43 of the platform 42 are larger or smaller than 90°, as illustrated. The angle of the first edge 33 of the rail 32 may have an absolute value in the range 10°-80°, e.g. 30°-60°. The angle of the first edge 43 of the platform 42 may have an absolute value in the range 10°-80°, e.g. 30°-60°. The angle of the first edge 33 of the rail 32 may be the same as the angle of the first edge 43 of the platform 42, as illustrated.

[0102] The platform 42 may be displaceable both forwards and backwards. While Figs 2a-c illustrate the platform 42 being displaced towards a row 30 to the right of the aisle 20 (as compared to the first direction 11 ), Fig. 3 illustrate the platform 42 being displaced towards a row 30 to the left of the aisle 20 (as compared to the first direction 11 ).

[0103] Fig. 4 is a side view of an aisle cart 40 carrying an item 2 in the form of a pallet 3 with goods 4. In Fig. 4, the pallet 3 is standing on the belt conveyor 52. For illustrative purposes the row cart 60 is not shown. However, the row cart 60 may stand on the platform 42 of the aisle cart 40, underneath the pallet 3.

[0104] Fig. 13 shows an aisle cart 40 at a designated row 30, in this case the row 30 to the right of the aisle 20 (as compared to the first direction 11 ). In the figure, the platform 42 is displaced towards the designated row 30 and the row cart 60 is entering the designated row 30. The row cart 60 may (as in Fig. 13) enter the designated row 30 empty, when collecting an item 2, e.g. the item 2 closest to the aisle 20. Alternatively, the row cart 60 may enter the designated row 30 while carrying an item 2 to be stored in the designated row 30. Fig. 13 further illustrates items 2 in the form of pallets 3 with goods 4 stored both in the row 30 to the left of the aisle 20 and in the row 30 to the right of the aisle 20.

[0105] Fig. 5 shows an aisle cart 40 comprising a first 42’ and a second 42” platform, the first platform 42’ being configured to support a left side wheel of the row cart 60 and the second platform 42” being configured to support a right side wheel of the row cart 60. The first 42’ and second 42” platform are separated by an open space 148. As seen in the figure, both the first 42’ and second 42” platform are displaceable relative to the at least one wheel 46 of the aisle cart 40. In the figure, both the first 42’ and second 42” platform have been displaced in the negative Y direction, towards the viewer. A platform 42 of the aisle cart 40 may be displaced by displacement means 58. The first 42’ and second 42” platform may be displaceable by a common displacement means 58, as illustrated. Displacement means 58 may comprise a motor of any sort (e.g. a stepper motor) or an actuator (e.g. a linear actuator). Alternatively or additionally, the displacement means 58 may comprise a hydraulic actuator or pneumatic actuator.

[0106] Fig. 5 further shows that the belt conveyor 52 may be attached to the platform 42 and configured to be displaced relative to the at least one wheel 46 of the aisle cart 40 together with the platform 42. The illustrated aisle cart 40 further comprises a motor 54 for driving the belt conveyor 52. Part of the aisle cart 40 in Fig. 5 is removed for illustrative purposes, to show the motor 54. The motor 54 may be immovably attached to the chassis 56 of the aisle cart 40 such that the motor 54 is prevented from being displaced relative to the at least one wheel 46 of the aisle cart 40. The aisle cart 40 may be configured to: drive the belt conveyor 52 by the motor 54 while the platform 42 is displaced relative to the at least one wheel 46 of the aisle cart 40; or declutch the belt conveyor 52 from the motor 54 before or while the platform 42 is displaced relative to the at least one wheel 46 of the aisle cart 40.

[0107] In Fig. 5, the aisle cart 40 comprises blocking elements 47, each blocking element 47 being a movable element which: in a blocking position, blocks the row cart 60 from leaving the platform 42; and in an unblocking position, unblocks the row cart 60 from leaving the platform 42. In Fig. 5 there are two blocking elements 47 at each side of the aisle cart 40. Each illustrated blocking element 47 is a lever pivotably attached to the platform 42. The aisle cart 40 may be configured to move the blocking element 47 from the blocking position to the unblocking position such that the blocking element 47 arrives at the unblocking position after the platform 42 has started displacing relative to the at least one wheel 46 of the aisle cart 40. In Fig. 5, the first 42’ and second 42” platform have been displaced in the negative Y direction, towards the viewer.

[0108] In Fig. 5 the blocking elements 47 at the end of the platforms 42’, 42” towards the viewer are in the unblocking position wherein the lever 47 has pivoted downwards (out of a slit 49). Thus, said blocking elements 47 are not blocking the travel path of the row cart.

[0109] In Fig. 5 the blocking elements 47 at the end of the platforms 42’, 42” away from the viewer are in the blocking position wherein the lever 47 has not pivoted downwards (out of a slit 49). Thus, said blocking elements 47 are blocking the travel path of the row cart. In other words, in Fig. 5, a row cart 60 may move out of the aisle cart 40 in the negative Y direction but not in the positive Y direction.

[0110] Figs 6a-c illustrate that the aisle cart 40 may comprise a guide member 110. Fig. 6a shows an aisle cart 40 on aisle rail 22 in the form of hollow beams 50. The support wheels 46 of the aisle cart 40 roll on the top surfaces 54t of the respective hollow beams 50 of the aisle rail 22. The illustrated aisle cart 40 comprises a guide member 110, being a member configured to guide the aisle cart 40 along the hollow beam 50 of the aisle rail 22 by engaging the rack 10. As illustrated, the aisle cart 40 may comprise several guide members 110. Fig. 6b and Fig. 6c show close-up views of the frontmost guide member 110 in Fig. 6a, as seen from different perspectives. The illustrated guide member 110 has three different means for engaging the rack 10, a first guide wheel 111 , a second guide wheel 112, and a protrusion 113. However, it should be understood that either one could be used on its own or in any combination with the others.

[0111] In Figs 6a-c, the guide member 110 comprises a first guide wheel 111 , being a wheel arranged to roll on a first side surface 51s of the hollow beam 50 and a second guide wheel 112, being a wheel arranged to roll on second side surface 52s of the hollow beam 50, the second side surface 52s of the hollow beam 50 being opposite to the first side surface 51s of the hollow beam 50. The first side surface 51s of the hollow beam 50 may be the outer side surface of the hollow beam while the second side surface 52s of the hollow beam 50 is the inner side surface of the hollow beam, as illustrated, or vice versa.

[0112] In Figs 6a-c, the guide member 110 comprises a protrusion 113 protruding in a direction of an axis 46A of the support wheel 46. The illustrated protrusion 113 is a plate.

[0113] Fig. 8 illustrates that the protrusion 113 may slide under a surface 10s of the rack 10 when the aisle cart 40 travels on the aisle rail 22. In Fig. 8 said surface 10s of the rack 10 is a bottom surface 70s of a ledge 70 extending in parallel with the hollow beam 50 of the aisle rail 22. Thus, the protrusion 113 is configured to engage a portion 17 of the rack (in this case the ledge 70) that extends in parallel with the hollow beam 50 of the aisle rail 22 of the rack 10.

[0114] The protrusion 113 may be arranged at a distance below the ledge 70, said distance may be 1-15 mm, e.g. 5 mm. The protrusion 113 may extend 20 mm under the ledge 70, in a horizontal direction perpendicular to the ledge. The protrusion 113 may extend 50 mm under the ledge 70, in a horizontal direction parallel to the ledge.

[0115] Fig. 7 illustrates a close-up view of the guide member 110 engaging the hollow beam 50 by the first 111 and second 112 guide wheel. A spacing between the first 111 and second 112 guide wheel may be larger than the width of the hollow beam 50, e.g. 2% larger than the width of the hollow beam 50.

[0116] Fig. 7 and Fig. 6c shows a connector 48 for connecting the chassis 56 of the aisle cart 40 to the protrusion 113 and to the first 111 and second 112 guide wheel. The connector 48 may e.g. comprise one or more bars or rods, e.g. made of steel.

[0117] Figs 9a-b illustrate that an aisle rail 22 may comprise a plurality of hollow beams 50. Fig. 9a and 9b are views of the same aisle rail 22, as seen from opposite sides.

[0118] Fig. 9a-b illustrate a section of an aisle rail 22 comprising a first 50’ and a second 50” hollow beam. The joint between the first 50’ and a second 50” hollow beam may be smooth.

[0119] In Fig. 9a-b, the first 50’ and the second 50” hollow beams are supported by a first 55 and second 56 plate, the first 55 and second 56 plate being arranged perpendicular to each other, the first plate 55 being in contact with a respective bottom surface 53b of the first 50’ and the second 50” hollow beams, the second plate 56 being in contact with a respective side surface 52s of the first 50’ and the second 50” hollow beams. Similar first 55 and second 56 plates are also seen in Fig. 6c.

[0120] Fig 10 illustrate a row cart 60 on row rail 32, in a cross-sectional view of the row rail 32. In other words, the row cart is standing in a row 30. A left and a right support wheel 66 of the row cart 60 are standing on respective row rails 32. The illustrated row rail 32 comprise a upper metal sheet 87 and a lower metal sheet 85, both being arranged horizontally. A side metal sheet 86 is arranged to connect the upper metal sheet 87 with the lower metal sheet 85. A protruding metal sheet 84 protrudes downwards from the lower metal sheet 85. In Fig. 10 an item 2, in the form of a pallet 3, is resting (i.e. supported) on the respective upper metal sheets 87 of the left and right row rail 32. Thus, the pallet 3 is stored on the row rail 32. The support wheels 66 of the row cart 60 are supported by the respective lower metal sheets 85 of the left and right row rail 32. The illustrated row cart 60 comprises a lifting device 62. In Fig. 10 the lifting device 62 is in a lowered position. Thus, the row cart may travel under the stored item 2. By raising the lifting device 62, the row cart 60 may lift the item 2 from the row rail 32.

[0121] The row cart 60 of Fig. 10 comprises guide members 120 configured to guide the row cart 60 onto the row rail 32 by engaging the side surface 183 of the row rail 32. In this case, the side surface 183 is a surface of the side metal sheet 86. The guide member 120 may be a guide wheel.

[0122] Fig 11 is a cross-sectional view of a row rail 32, corresponding to the left row rail 32 of Fig. 10. As described above, the illustrated row rail 32 comprises a upper metal sheet 87, a side metal sheet 86, a lower metal sheet 85, and a protruding metal sheet 84.

[0123] The illustrated row rail 32 comprises an upper horizontal surface 82 for supporting the item 2, the upper horizontal surface 82 being a surface of the illustrated upper metal sheet 87.

[0124] The illustrated row rail 32 comprises a lower horizontal surface 81 for a wheel 66 of the row cart 60 to travel on, the lower horizontal surface 81 being a surface of the illustrated lower metal sheet 85.

[0125] In the figure, the upper horizontal surface 82 comprise an outer side 82o and an inner side 82i. Similarly, the lower horizontal surface 81 comprise an outer side 81 o and an inner side 81 i.

[0126] The illustrated row rail 32 comprises a side surface 183, the side surface 183 being a surface of the side metal sheet 86. The illustrated side surface 183 is a flat inclined surface 83.

[0127] In Fig. 11 , the outer side 81 o of the lower horizontal surface 81 is connected to the inner side 82i of the upper horizontal surface 82 by the side surface 183. Further, in Fig. 11 , the inner side 82 i of the upper horizontal surface 82 is further away from the center axis of the row 30 than the outer side 81 o of lower horizontal surface 81 .

[0128] In Fig. 11 , the upper metal sheet 87, the side metal sheet 86, the lower metal sheet 85, and the protruding metal sheet 84 form a single metal sheet.

[0129] Fig. 11 further illustrates a row rail supporting bracket 130.

[0130] The illustrated row rail supporting bracket 130 comprises a first plate 131 arranged horizontally and supporting a back side 85b of a lower metal sheet 85 of the row rail 32.

[0131] The illustrated row rail supporting bracket 130 further comprises a second plate 132 supporting a back side 86b of the side metal sheet 86.

[0132] The illustrated row rail supporting bracket 130 further comprises a third plate 133. The third plate 133 may be fastened to the protruding metal sheet 84 by a fastener (not shown), e.g. a fastener in the form of a bolt, a screw, or a rivet.

[0133] Fig. 14 is a perspective view of a row rail 32 similar to the row rails 32 of Figs 10 and 11.

[0134] The illustrated row rail 32 comprises an upper horizontal surface 82 for supporting the item 2, the upper horizontal surface 82 being a surface of the illustrated upper metal sheet 87.

[0135] The illustrated row rail 32 comprises a lower horizontal surface 81 for a wheel 66 of the row cart 60 to travel on, the lower horizontal surface 81 being a surface of the illustrated lower metal sheet 85.

[0136] The illustrated row rail 32 comprises a side surface 183, the side surface 183 being a surface of the side metal sheet 86. The illustrated side surface 183 is a flat inclined surface 83.

[0137] The illustrated row rail 32 further comprises a protruding metal sheet 84.

[0138] Fig 12 is a close-up view of the row rail 32 at the entrance 35 of the row 30. As illustrated, the row rail 32 may comprise a bridge rail 90 forming a bridge for the row cart 60 to travel across. The bridge rail 90 may be part of the row rail 32. Thus, the row cart 60 may travel across the bridge rail 90 onto a further section of the row rail 32. Thus, the row rail 32 may be produced in a number of long sections which may be connected to form most of the row rail 32. The bridge rail 90 may then be a short section of the row rail 32 which acts as an adaptor for easing the transfer of the row cart 60 from the aisle cart 40 into the row 30.

[0139] The illustrated bridge rail 90 comprises a horizontal surface 81 for the wheel 66 of the row cart 60 to travel on. The illustrated bridge rail 90 has a first end 95 close to the aisle 20 and a second end 96 further away from the aisle.

[0140] The horizontal surface 81 of the illustrated bridge rail 90 may be wider at the first end 95 than at the second end 96.

[0141] The horizontal surface 81 of the illustrated bridge rail 90 comprises an edge 33 facing the aisle 20, wherein an angle of the edge 33 deviates from 90°.

[0142] The illustrated bridge rail 90 comprises a side surface 183. An angle between the side surface 183 of the bridge rail 90 and the horizontal surface 81 of the bridge rail 90 may be smaller in a first cross-section of the bridge rail 90 than in a second cross section of the bridge rail 90. The first cross-section of the bridge rail 90 may be at the first end 95. The second cross-section of the bridge rail 90 may be at the second end 96.

[0143] Fig. 15a-e illustrate a row rail 32 and a platform 42 of an aisle cart 40. For clarity, the rest of the aisle cart 40 is not shown. The row rail 32 comprising a bridge rail 90 for the row cart 60 to travel across. Fig. 15a is a perspective view. Fig. 15b is a cross-sectional view of the platform 42. Fig. 15c is a cross-sectional view of the bridge rail 90 at a first end 95 close to the aisle 20. Fig. 15d is a cross-sectional view of the bridge rail 90 at a second end 96 close to the aisle 20 further away from the aisle 20. Fig. 15e is a cross-sectional view of the row rail 32 at a section adjacent to the bridge rail 90.

[0144] In the Fig. 15e cross-sectional view of the row rail 32, the row rail 32 comprises an upper horizontal surface 82, for supporting the item 2, and a lower horizontal surface 81 , for a wheel 66 of the row cart 60 to travel on. The inner side of the upper horizontal surface 82 is further away from the center axis of the row 30 than the outer side of lower horizontal surface 81 . The upper horizontal surface 82 and the lower horizontal surface 81 are connected by a side surface 183, which is inclined.

[0145] In the Fig. 15b cross-sectional view of the platform 42, the platform 42 is connected to a side surface 283 which is in the illustration is vertical.

[0146] In the Fig. 15c-d cross-sectional views of the bridge rail 90, it is seen that the bridge rail 90 may act as an adaptor between the platform 42 and the further section of the row rail 32. In the cross-sectional view of the bridge rail 90 at the first end 95, Fig. 15c, the cross-section of the bridge rail 90 is similar to the cross-section of the platform 42 and the side surface 283 connected to the platform 42, seen in Fig. 15b. Further, in the cross-sectional view of the bridge rail 90 at the second end 96, Fig. 15d, the cross-section of the bridge rail 90 is similar to the cross-section of the further section of the row rail 32 in Fig. 15e. Thus, the horizontal surface 81 of the bridge rail 90 is wider at the first end 95 than at the second end 96. Further, an angle between the side surface 183 of the bridge rail 90 and the horizontal surface 81 of the bridge rail 90 is smaller at the cross-section at the first end 95 than at the second end 96. As seen in the figures, the angle (with respect to the direction of the row 30) of the first edge 33 of the bridge rail 90 and the angle (with respect to the direction of the row 30) of the first edge 43 of the platform 42 may both differ from 90°. Said angles may e.g. be the same. In the above the inventive concept has mainly been described with reference to a limited number of examples. However, as is readily appreciated by a person skilled in the art, other examples than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended claims.

Claims

CLAIMS1 . A method for storing an item (2) at a storage position (16) in a rack (10), the rack (10) comprising: an aisle (20) extending in a first direction (11 ); and a plurality of rows (30), each row (30) extending in a second direction (12) from a respective entrance (35) at the aisle (20), the storage position (16) being a position, for storing the item (2), in a designated row (30) of the plurality of rows (30); the method using an aisle cart (40) and a row cart (60) for transporting the item (2) in the rack (10), the aisle cart (40) comprising at least one wheel (46) for moving the aisle cart (40) along the aisle (20) and the row cart (60) comprising at least one wheel (66) for moving the row cart (60) along the rows (30); the method comprising: transporting the row cart (60) and the item (2) along the aisle (20) using the aisle cart (40), the aisle cart (40) comprising a platform (42) supporting the at least one wheel (66) of the row cart (60) while the aisle cart (40) transports the row cart (60); stopping the aisle cart (40) at the entrance (35) of the designated row (30); displacing the platform (42), relative to the at least one wheel (46) of the aisle cart (40), in the second direction (12) such that a gap between the platform (42) and the entrance (35) of the designated row (30) is reduced; transferring, by the row cart (60), the item (2) into the designated row (30), wherein the at least one wheel (66) of the row cart (60) crosses the reduced gap; transporting, by the row cart (60), the item (2) along the designated row (30); placing, by the row cart (60), the item (2) at the storage position (16) in the designated row (30).

2. Method according to claim 1 , wherein the aisle cart (40) moves at a speed of at least 0.3 m / s along the aisle (20).

3. Method according to claim 1 or 2, wherein the aisle cart (40) further comprises a belt conveyor (52) for pulling the item (2) on or off the aisle cart (40) and supporting the item (2) while the aisle cart (40) transports the item (2), the belt conveyor (52) being attached to the platform (42) and configured to be displaced relative to the at least one wheel (46) of the aisle cart (40) together with the platform (42); a motor (54) for driving the belt conveyor (52), the motor (54) being immovably attached to a chassis (56) of the aisle cart (40) such that the motor (54) is prevented from being displaced relative to the at least one wheel (46) of the aisle cart (40); the method further comprising: driving the belt conveyor (52) by the motor (54), such that the item (2) supported by the belt conveyor (52) is moved by the belt conveyor (52) in the second direction (12), wherein the belt conveyor (52) belt is driven while the platform (42) is displaced relative to the at least one wheel (46) of the aisle cart (40); or declutching the belt conveyor (52) from the motor (54) before or while the platform (42) is displaced relative to the at least one wheel (46) of the aisle cart (40).

4. A system (1 ) for storing an item (2) at a storage position (16), the system (1 ) comprising a rack (10) comprising: an aisle (20) extending in a first direction (11 ); and a plurality of rows (30), each row (30) extending in a second direction (12) from a respective entrance (35) at the aisle (20); wherein the storage position (16) is a position, for storing the item (2), in a designated row (30) of the plurality of rows (30); an aisle cart (40) and a row cart (60) for transporting the item (2) in the rack (10), the aisle cart (40) comprising at least one wheel (46) for moving the aisle cart (40) along the aisle (20) and the row cart (60) comprising at least one wheel for moving the row cart (60) along the rows (30); the aisle cart (40) being a cart for transporting the row cart (60) and the item (2) along the aisle (20), the aisle cart (40) comprising a platform (42), the platform (42) being configured to support the at least one wheel of the row cart (60) while the aisle cart (40) transports the row cart (60), theplatform (42) being displaceable relative to the at least one wheel (46) of the aisle cart (40); the row cart (60) being a cart for transporting the item (2) along the designated row (30); wherein the aisle cart (40) is configured to, at the entrance (35) of the designated row (30), displace the platform (42) relative to the at least one wheel (46) of the aisle cart (40) in the second direction (12) such that a gap between the platform (42) and the entrance (35) of the designated row (30) is reduced.

5. System (1 ) according to claim 4, wherein the designated row (30) comprises a rail (32) for the wheel of the row cart (60) to travel on, the rail (32) extending in the second direction (12); wherein the gap between the platform (42) and the entrance (35) of the designated row (30) is a gap between a first edge (33) of the rail (32) of the designated row (30) and a first edge (43) of the platform (42) of the aisle cart (40); wherein an angle of the first edge (33) of the rail (32) is an angle between the first edge (33) of the rail (32) and the second direction (12); wherein an angle of the first edge (43) of the platform (42) is an angle between the first edge (43) of the platform (42) and the second direction (12) when the aisle cart (40) is in the aisle (20); wherein both the angle of the first edge (33) of the rail (32) and the angle of the first edge (43) of the platform (42) are larger or smaller than 90°.

6. System (1 ) according to claim 5, wherein both the angle of the first edge (33) of the rail (32) and the angle of the first edge (43) of the platform (42) deviates from 90° by at least 10°.

7. System (1 ) according to any one of claims 4-6, wherein the aisle cart (40) is configured to, at the entrance (35) of the designated row (30), displace the platform (42) relative to the at least one wheel (46) of the aisle cart (40) by at least 20 mm.

8. System (1 ) according to any one of claims 4-7, the system (1 ) being configured such that the gap between the platform (42) and the entrance (35)of the designated row (30) is less than 50 mm, when the aisle cart (40), at the entrance (35) of the designated row (30), has displaced the platform (42) relative to the at least one wheel (46) of the aisle cart (40).

9. System (1 ) according to any one of claims 4-8, wherein the platform (42) is displaceable both forwards and backwards in the second direction (12) from a first position of the platform (42), the first position of the platform (42) being a position of the platform (42) relative to the at least one wheel (46) of the aisle cart (40) during transport of the row cart (60) and the item (2) along the aisle (20).

10. System (1 ) according to any one of claims 4-9, wherein the aisle cart (40) comprises two platforms, the two platforms being a first (42’) and a second (42”) platform, the first platform (42’) being configured to support a left side wheel of the row cart (60) and the second platform (42”) being configured to support a right side wheel of the row cart (60), wherein the first (42’) and second (42”) platform are separated by an open space (148); wherein both the first (42’) and second (42”) platform are displaceable relative to the at least one wheel (46) of the aisle cart (40); and wherein the aisle cart (40) is configured to, at the entrance (35) of the designated row (30), displace both the first (42’) and second platform (42”) relative to the at least one wheel (46) of the aisle cart (40) in the second direction (12).11 . System (1 ) according to any one of claims 4-10, wherein the aisle cart (40) further comprises a belt conveyor (52) for pulling the item (2) onto the aisle cart (40) and supporting the item (2) while the aisle cart (40) transports the item (2), the belt conveyor (52) being attached to the platform (42) and configured to be displaced relative to the at least one wheel (46) of the aisle cart (40) together with the platform (42).

12. System (1 ) according to claim 11 , wherein the aisle cart (40) further comprises a motor (54) for driving the belt conveyor (52), the motor (54) being immovably attached to a chassis (56) of the aisle cart (40) such that the motor(54) is prevented from being displaced relative to the at least one wheel (46) of the aisle cart (40), wherein the aisle cart (40) is configured to: drive the belt conveyor (52) by the motor (54) while the platform (42) is displaced relative to the at least one wheel (46) of the aisle cart (40); or declutch the belt conveyor (52) from the motor (54) before or while the platform (42) is displaced relative to the at least one wheel (46) of the aisle cart (40).

13. System (1 ) according to any one of claims 4-12, wherein the aisle cart (40) comprises a blocking element (47), the blocking element (47) being a movable element which: in a blocking position, blocks the row cart (60) from leaving the platform (42); and in an unblocking position, unblocks the row cart (60) from leaving the platform (42); wherein the aisle cart (40) is configured to move the blocking element (47) from the blocking position to the unblocking position such that the blocking element (47) arrives at the unblocking position after the platform (42) has started displacing relative to the at least one wheel (46) of the aisle cart (40).

14. System (1 ) according to claim 13, wherein the aisle cart (40) is configured to mechanically trigger the movement of the blocking element (47) from the blocking position to the unblocking position by the platform (42) being displaced.

15. An aisle cart (40) for transporting a row cart (60) and an item (2) along an aisle (20) of a rack (10), the aisle cart (40) being movable along the aisle (20) in a first direction (11 ), the aisle cart (40) comprising: at least one wheel (46) for moving the aisle cart (40) along the aisle; and a platform (42) configured to support at least one wheel of the row cart (60) while the aisle cart (40) transports the row cart (60), the platform(42) being displaceable relative to the at least one wheel (46) of the aisle cart (40); wherein the aisle cart (40) is configured to displace the platform (42) relative to the at least one wheel (46) of the aisle cart (40) in a second direction (12) when the aisle cart (40) is at an entrance (35) of a designated row (30), wherein the designated row (30) is a row (30) extending in the second direction (12) from the entrance (35) of the row (30), the entrance (35) of the row (30) being an entrance at the aisle (20).

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