Field of the Invention

This application pertains to the storage of cargo containers in a multi-level rack capable of horizontally displaceably receiving multiple containers on each level under programmed control.

Background of the Invention

Inbound cargo shipping containers are conven- tionally unloaded from container ships by cranes and transported by container carrying vehicles into a dockside container storage yard. The same cranes and vehicles are used to transport outbound containers from the container yard and load them onto container ships for export.

If the container yard is large relative to the number of containers which must be stored then the con¬ tainers are laid on the ground in rows. If the container yard is small relative to the number of containers which must be stored (as is typically the case) then the con¬ tainers are stacked atop one another to conserve valuable space.

Containers stored in the yard are commonly shuffled from one location to another in a continuous effort to speed the loading and unloading of container ships. For example, a group of containers may be moved to clear an area in the yard to receive an inbound shipload of containers. The inbound containers can be unloaded and moved into the cleared common storage area more quickly than would be the case if each inbound container had to be moved into a random storage location in the yard. Similar¬ ly, a group of outbound containers may be moved into a pre- cleared yard storage area in preparation for loading the entire group of outbound containers onto a ship which is about to arrive, or which is being unloaded. The outbound containers can be loaded onto the ship from a common storage area more quickly than would be the case if each

outbound container had to be moved to the ship from a random storage location in the yard.

The continuous shuffling of stored containers causes a number of problems. Although records are usually kept of the yard location in which each newly arriving container is stored, those records are often not updated to reflect every shuffling movement of each container. For example, if an outbound container is stacked beneath two other containers which are not outbound, then those two must be lifted off the outbound container and moved to another storage location before the outbound container can be moved. The other two containers are not normally moved back into the stack location from which they were moved. Moreover, the operator who moves them may not note their new location(s) in the yard's records. Even though those two containers may be moved only a short distance, con¬ fusion can result when they have to be located for loading or for transport to an outbound ship, especially if they are repeatedly moved in a series of unrelated shuffling operations. Time is thus wasted while "lost" containers are located.

The ability to manage container movements is also adversely affected by the inability to precisely locate and track the movement of individual containers within the yard. Even if a container's location is known, repeated shuffling operations may have "buried" that container beneath and/or behind many other containers, all of which must be moved (i.e. shuffled) to gain access to the desired container. Repeated container shuffling also increases the potential for damaging the containers.

Computerized systems have been developed to automate the process of locating and tracking individual containers stored within a container yard. However, because such systems typically rely on human driven ve-

hides to move containers, they require human operator input to indicate that containers have been shuffled into different locations. Such systems are therefore subject to the same problems outlined above if the operator fails to input information respecting each and every container movement. In a busy container yard, with many simultaneous container movements continually ongoing, it is impractical to record each and every container movement. Even if the location of every container in the yard is known, and even if every container movement is tracked to reflect the new location of every shuffled container, significant time is still required for conventional container handling equip¬ ment to shuffle the containers about the yard and transport them to and from container ships.

The present invention provides a programmable, compact, high density container storage apparatus which facilitates precise location of every stored container; precise tracking of every container movement; and, control- lable container shuffling capable of significantly reducing the time required to move selected containers between container ships and the container storage apparatus.

Summary of the Invention In accordance with the preferred embodiment, the invention provides a multi-level container storage rack. A container transport aisle extends through the rack from top to bottom and between opposed ends of the rack. A plurality of container storage positions are provided on each of the levels and on each side of the aisle. A container elevator means is provided for vertically dis¬ placing containers within the aisle to a selected one of the levels. A container transfer means is also provided for transferring containers between the container elevator means and a selected side of the selected level. The storage positions on each side of the aisle are preferably

horizontally displaceable toward or away from the aisle, along each of the levels.

The container transfer means horizontally trans- fers inbound containers from the container elevator means onto the selected side of the selected level. Storage positions on each side of the aisle are interconnected (advantageously, in endless loop fashion) such that trans¬ fer of a container from the container elevator horizontally displaces, away from the aisle, containers previously transferred onto the side of the level to which the con¬ tainer is transferred. In other words, the container transfer means horizontally transfers the container from the elevator into a storage position adjacent the aisle on a selected side of the selected level, which in turn horizontally displaces all other storage positions on the selected side of the selected level one storage position away from the aisle.

The container transfer means horizontally trans¬ fers outbound containers from the selected side of the selected level onto the container elevator means. Slidable transfer of a container from a selected side of a selected level onto the elevator horizontally displaces, toward the aisle, containers remaining on the selected side of the selected level. In other words, the container transfer means horizontally transfers the container from a storage position adjacent the aisle on a selected side of a se¬ lected level onto the elevator, which in turn horizontally displaces all other storage positions on the selected side of the selected level one storage position towards the aisle.

Brief Description of the Drawings Figures 1(a) through l(n) are elevation views showing one end of a cargo container storage apparatus constructed in accordance with the preferred embodiment of

the invention and depicting the sequence of steps by which four selected containers may be retrieved from storage for transportation to a container ship.

Detailed Description of the Preferred Embodiment

The drawings depict a container storage rack 10 having multiple levels 12 through 30. A suitably anchored framework (not shown) supports rack 10 and containers stored therein. A container transport aisle 32 extends through rack 10 from top to bottom and between opposed ends of rack 10. A plurality of container storage positions are provided on each of levels 12 through 30, on both sides of aisle 32. Rectangles depict the ends of containers stored in individual storage positions within rack 10. Empty storage positions in rack 10 are denoted by the absence of rectangles at the outer ends of levels 12 through 30, on either side of aisle 32.

A container elevator means such as a powered hoist, container spreader, crane or elevator 34 is mounted in aisle 32 for vertically displacing containers within aisle 32 to a selected one of levels 12 through 30. A container transfer means such as a double acting hydraulic cylinder 36 is mounted on elevator 34 for transferring containers between elevator 34 and a selected side of a selected one of levels 12 through 30. The storage posi¬ tions on each side of aisle 32 are interconnected in endless loop fashion so that they may be horizontally displaced toward or away from aisle 32, along each of levels 12 through 30.

Double acting cylinder 36 horizontally transfers inbound containers from elevator 34 onto a selected side of a selected one of levels 12 through 30. Transfer of a container from elevator 34 horizontally displaces, away from aisle 32, containers previously transferred onto the same side and level of rack 10 to which the inbound con-

tainer is transferred. More particularly, double acting cylinder 36 horizontally transfers the inbound container from elevator 34 into a storage position adjacent aisle 32 on a side and level of rack 10 selected for storage of the inbound container. Because the storage positions are interconnected as aforesaid, transfer of the inbound container from elevator 34 frees a storage position adjac¬ ent aisle 32 to receive the inbound container by horizon¬ tally displacing, one storage position away from aisle 32, all other storage positions on the side and level of rack 10 selected for storage of the inbound container.

Double acting cylinder 36 horizontally transfers outbound containers onto elevator 34 from storage positions adjacent aisle 32. Transfer of an outbound container onto elevator 34 horizontally displaces, toward aisle 32, any containers remaining on the same side and level from which the outbound container was transferred. More particularly, double acting cylinder 36 horizontally transfers the outbound container from its storage position adjacent aisle 32 onto elevator 34. Because the storage positions are interconnected as aforesaid, transfer of the outbound container onto elevator 34 does not leave an empty storage position adjacent aisle 32. Instead, transfer of the outbound container onto elevator 34 horizontally displaces, one storage position toward aisle 32, all other storage positions on the side and level of rack 10 from which the outbound container is withdrawn, by dragging the entire group of storage positions (together with any containers stored therein) toward aisle 32 as the outbound container is transferred onto elevator 34. Accordingly, any con¬ tainers remaining on the same side and level from which the outbound container was transferred remain adjacent one an¬ other, with the innermost container immediately adjacent aisle 32.

The operation of elevator 34 and double acting cylinder 36 may be programmed to store, retrieve, and/or shuffle containers in any desired fashion. For example, Figures 1(a) through l(n) depict one possible sequence of steps by which four outbound containers labelled 1, 2, 3 and 4 previously stored in rack 10 in the positions shown in Figure 1(a) may be retrieved for transportation to a container ship. As will be seen, the outbound containers are initially moved into a contiguous group of storage positions on the right hand side of level 12 immediately adjacent aisle 32. The contiguously grouped outbound containers are then sequentially transferred into aisle 32 onto container carrying vehicles which transport the containers to the container ship. Those skilled in the art will recognize that this enables the container yard personnel to plan and schedule container movements with considerable flexibility. For example, outbound containers may be contiguously grouped well before the ship is ready to receive them. As soon as the ship is ready the con- tainers may be transferred to the ship rapidly and effi¬ ciently. As will be seen, the exact position of every stored container is always known, notwithstanding complex shuffling of containers stored within rack 10.

The following description illustrates how out¬ bound containers 1 through 4 may be contiguously pre- grouped so that they may be sequentially delivered, in ascending numeric order, to the container ship. It will however be understood that the outbound containers need not be grouped before they are delivered to the ship, although grouping will speed the container transfer operation, as aforesaid. It will also be understood that the outbound containers may be grouped in any desired sequence.

Container 4 is "buried" on level 12, on the left side of aisle 32, behind seven "static" containers which are to remain in storage. The seven static containers must

be shuffled into other storage positions in rack 10 in order to bring container 4 adjacent aisle 32 so that it may be transferred to the grouping area (which, for the pur¬ poses of this example, is the right hand side of level 12 immediately adjacent aisle 32) . As may be seen by compar¬ ing Figures 1(a) and 1(b) , the static container adjacent aisle 32 is transferred onto elevator 34 and lifted to level 14. Withdrawal of the static container from the left side of level 12 horizontally displaces (i.e. drags) all of the containers remaining on the left side of level 12 one storage position toward aisle 32. A suitably programmed computer tracks the movement of each container. When the static container aforesaid is withdrawn from level 12 as aforesaid, the computer updates its records to indicate that the containers remaining on the left side of level 12 have moved one storage position toward aisle 32

When the static container has been lifted to level 14, as depicted in Figure 1(b), double acting cylin- der 36 horizontally displaces the container to the left, storing it on the left side of level. The static con¬ tainers previously stored on the left side of level 14 are displaced one storage position away from aisle 32. The computer again updates its records to indicate that the containers previously stored on the left side of level 14 have moved one storage position away from aisle 32; and, that the static container withdrawn from level 12 has moved into the storage position on the left side of level 14 immediately adjacent aisle 32.

As may be seen by comparing Figures 1(a) and 1(c), the remaining six static containers behind which container 4 is buried are similarly sequentially shuffled from the left side of level 12 into other static storage positions on the left side of level 14,. the left side of level 18 and the right side of level 20 to bring container 4 into position immediately adjacent aisle 32 on the left

side of level 12, as shown in Figure 1(c). As each con¬ tainer is withdrawn from or inserted into a storage posi¬ tion, the computer updates its records to reflect the new position of that container and all other containers dis- placed therewith.

As may be seen by comparing Figures 1(c) and 1(d), container 4 is transferred onto elevator 34 from its position adjacent aisle 32 on the left side of level 12 and then immediately transferred from elevator 34 into the position adjacent aisle 32 on the right side of level 12. Container 4 is thus stored within the previously defined grouping area.

Container 3 is buried on level 20, on the left side of aisle 32, behind two static containers which are to remain in storage. The two static containers must be shuffled into other storage positions in rack 10 in order to bring container 3 adjacent aisle 32 so that it may be transferred to the grouping area. As may be seen by comparing Figures 1(d) and 1(e), the two static containers behind which container 3 is buried are sequentially shuf¬ fled from the left side of level 20 into other static storage positions on the right side of level 20 and the left side of level 22, _^ to bring container 3 into position immediately adjacent aisle 32 on the left side of level 20. As each container is withdrawn from or inserted into a storage position, the computer updates its records to reflect the new position of that container and all other containers displaced therewith.

As may be seen by comparing Figures 1(e) and 1(f), container 3 is transferred onto elevator 34 from its position adjacent aisle 32 on the left side of level 20, lowered to level 12, and then transferred from elevator 34 into the position adjacent aisle 32 on the right side of level 12, displacing container 4 and the other static

containers on the right side of level 12 one storage position away from aisle 32. Containers 3 and 4 are thus stored within the grouping area.

Container 2 is buried on level 26, on the left side of aisle 32, behind one static container which is to remain in storage. That static container must be shuffled into another storage position in rack 10 in order to bring container 2 adjacent aisle 32 so that it may be transferred to the grouping area. As may be seen by comparing Figures 1(f) and 1(g), the static container behind which container 2 is buried is shuffled from the right side of level 26 into another static storage position on the left side of level 24, to bring container 3 into position immediately adjacent aisle 32 on the right side of level 26. The computer again updates its records to reflect the new position of each shuffled container and all other con¬ tainers displaced therewith.

As may be seen by comparing Figures 1(g) and

1(h), container 2 is transferred onto elevator 34 from its position adjacent aisle 32 on the right side of level 26, lowered to level 12, and then transferred from elevator 34 into the position adjacent aisle 32 on the right side of level 12, displacing containers 3 and 4 and the other static containers on the right side of level 12 one storage position away from aisle 32. Containers 2, 3 and 4 are thus stored within the grouping area.

Container 1 is not buried, but is already adjac¬ ent aisle 32 so it may be directly transferred to the grouping area without first shuffling any static con¬ tainers. As may be seen by comparing Figures 1(h) and l(i), container 1 is transferred onto elevator 34 from its position adjacent aisle 32 on the right side of level 30, lowered to level 12, and then transferred from elevator 34 into the position adjacent aisle 32 on the right side of

level 12, displacing containers 2, 3 and 4 and the other static containers on the right side of level 12 one storage position away from aisle 32. Containers 1, 2, 3 and 4 are thus stored within the grouping area. The computer again updates its records to reflect the new position of each transferred container and all other containers displaced therewith.

When the container ship (not shown) is ready to receive the outbound containers, four conventional con¬ tainer carrying vehicles (not shown) are driven to rack 10. Aisle 32, elevator 34 and double acting cylinder 36 are constructed to allow the container carrying vehicles to pass through aisle 32 and to allow double acting cylinder 36 to transfer containers from rack 10 to the container carrying vehicles.

The first container carrying vehicle is driven into one end of aisle 32 and stopped adjacent container 1. Double acting cylinder 36 transfers container 1 from the grouping area to the first container carrying vehicle, which is then driven out through the opposite end of aisle 32 to the ship, as depicted graphically in Figure l(j). The computer then updates its records to reflect the fact that container 1 is no longer in storage, and to reflect the new storage positions of containers 2, 3 and 4 and the other static containers stored on the right side of level 12, all of which are horizontally displaced one storage position toward aisle 32 as container 1 is transferred to the first container carrying vehicle.

As the first container carrying vehicle exits aisle 32 with container 1, the second container carrying vehicle is driven into aisle 32 and stopped adjacent container 2, which is now adjacent aisle 32, as may be seen in Figure l(j). Double acting cylinder 36 transfers container 2 from the grouping area to the second container

carrying vehicle, which is then driven out through the opposite end of aisle 32 to the ship, as depicted graphi¬ cally in Figure 1(k) . The computer again updates its records to reflect the fact that container 2 is no longer in storage, and to reflect the new storage positions of containers 3 and 4 and the other static containers stored on the right side of level 12, all of which are horizontal¬ ly displaced one storage position toward aisle 32 as container 2 is transferred to the second container carrying vehicle.

As graphically depicted in Figures 1(1) and l(m) , containers 3 and 4 are similarly sequentially transferred to the third and fourth container carrying vehicles re- spectively and driven to the ship. Figure l(n) depicts rack 10 after the four outbound containers have been removed, with the remaining static containers in storage.

Roughly 5% of the container storage positions available within rack 10 should be left vacant at all times to ensure that containers may be shuffled with reasonable flexibility.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example, aisle 32 need not divide rack 10 into left and right halves, as depicted in the drawings. Instead, the aisle may be on one side or the other of rack 10, with no container storage levels on the opposite side of the aisle. It is however expected that greater con¬ tainer storage capacity and more efficient container shuffling and grouping capability will be attained by providing container storage levels on both sides of aisle 32. As another example, the apparatus may be extended, to provide additional container storage capacity and greater

shuffling and grouping flexibility, by placing a plurality of multi-level storage racks identical to rack 10 side by side such that aisle 32 extends longitudinally through the entire group of racks.

The operation of elevator 34 and double acting cylinder 36 may be programmed for storage, retrieval and/or shuffling of containers in any desired fashion. Con¬ tainers may be grouped in any desired manner to expedite their transfer between rack 10 and the container ship(s) . For example, containers may be grouped according to their destination port, their outbound shipping dates, their ports of origin, or any other desired parameter. The programming may also be optimized, with the aid of known queuing and programming techniques, to minimize the dis¬ placement of elevator 34, or to maximize the speed of the shuffling operation as containers are stored, retrieved and/or shuffled into groups. Accordingly, the scope of the invention is to be construed in accordance with the sub- stance defined by the following claims.