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

More specifically the invention relates to a storage system for storing items.

The present invention is an improvement upon the applicant's AutoStore ® system generally (illustrated in Fig 1) and in particular is an improvement upon applicant's prior invention disclosed in

The Applicant's already known AutoStore® system is a storage system comprising a three dimensional storage grid containing storage bins that are stacked on top of each other to a certain height. The storage grid is constructed as aluminum columns interconnected by top rails. A number of vehicles, or robots, are arranged on the top rails. Each vehicle is equipped with a lift for picking up, carrying, and placing bins that are stored in the storage grid.

Such a storage system of the background art has been illustrated in fig. 1. The known storage system comprises a grid structure of storage cells. Each cell is arranged to accommodate a vertical stack of storage bins. The known storage system further comprises a vehicle which is arranged to move at the top level of the grid structure and also arranged to receive a bin from a storage cell. The known storage system may include a plurality of such vehicles, as illustrated. The top level of the grid structure includes rails arranged in a grid pattern across the top of the stacks. A first set of parallel rails guide movement of the vehicles in a first direction (X) across the top of the grid structure, and a second set of parallel rails, arranged perpendicular to the first set, guide movement of the vehicles in a second direction (Y), perpendicular to the first direction. In this way, the grid of rails allow movement of the vehicles in two dimensions in the X-Y plane, so that a vehicle can be moved into position above any of the stacks.

When an article is to be retrieved from a bin, the robot vehicle is arranged to pick up the storage bin containing the article and transport it to a bin lift device. The bin lift device will transport the storage bin to a delivery station, where the article is retrieved from the storage bin. The storage bin, typically having remaining articles, is thereafter returned to the storage grid by means of the bin lift device and a robot vehicle.

The same procedure is used for refilling and storing items into the storage grid. First, items are filled into a storage bin at a supply station, normally at the same location as the delivery station. The bin lift device is then lifting the storage bin up to the upper level where a robot vehicle is transporting the storage bin into its destination in the storage grid.

A storage control and communication system may be used to monitor inventory, location of storage bins (within the storage grid and/or during transport), charge level of robot vehicles, etc. The storage control and communication system may further be provided with communication means for controlling the traffic of robot vehicles in order to avoid collision.

During busy periods several robot vehicles will operate simultaneously, and to prevent the vehicles from colliding or having to wait, the vehicles need to be able to pass each other. This is traditionally achieved by designing at least some of the rails in one of the perpendicular directions with a double track.

In order to allow an increase in the number of remotely operated vehicles operating simultaneously on the top rails of the three dimensional storage grid, the applicant has also developed single cell vehicles, where each vehicle occupies only a single cell. Each vehicle will operate very close to each other, e.g. as close as 4mm. In order to make the traffic efficient, it is desirable that the vehicles may pass each other in both directions.

In order for such single cell vehicles to pass each other in both directions a dual track arrangement can be provided in both the X and the Y direction. A dual track arrangement will have at least a center ridge separating the two tracks of a dual track arrangement in both the X and the Y directions. In order for the vehicles to cross from one grid cell to another in a dual track arrangement, the intersection of the tracks in the X and Y directions must be free of the center rail at a "crossroads", otherwise the wheels will encounter a ridge as they pass a perpendicular track.

One arrangement to provide such a dual track having a center ridge separating the tracks (and a ridge-fee crossroads) is to provide a plurality of square frame elements at the top of the grid structure arranged adjacent to each other to define the cells of the grid. The square frame elements have inner ridges along each rail of the frame, and a "half ridge" of half thickness along the outer edges of the rails of the frame. When two such frames are arranged adjacent to each other, the "half ridges" will abut to form the center ridge of a dual track, while the inner ridges of the adjacent rails will cooperate to form two outer ridges of the dual track. The half ridges of the rails are arranged shorter than the length of the rails, such that the thusly formed center ridges stop short of a ridge-free crossroads.

A problem with such an arrangement is that if the grid structure comes out of vertical alignment, the adjacent square frames at the top of the grid may move out of alignment with each other. If that occurs, the "half ridges" defining the center ridge may be moved longitudinally with respect to each other. If this occurs, one of the half ridges will protrude into the "crossroads" and possibly impede the wheels of a vehicle. Alignment of the tracks is particularly important the closer the vehicles are designed to pass one another. The object of the invention is to provide a more flexible rail arrangement for vehicles in a storage system, where the needs for increased simultaneous vehicle operation are facilitated.

The object of the invention is achieved by means of the features of the patent claims.

A rail arrangement for vehicles in a storage system comprises a first set of parallel rails and a second set of parallel rails. The first and second sets form a grid in that the second set is arranged perpendicular to the first set and intersecting the first set. Each of the rails of both sets of rails comprises extruded elements having two parallel tracks separated by a center ridge adapted for receiving and guiding the wheels of the vehicles. The two parallel tracks ensure that vehicles may pass each other. To ensure this, the distance between the two parallel tracks should be adapted to the size of the vehicle.

The grid formed by the parallel rails comprises a number of cells according to the number of parallel rails of each set, i.e. two parallel rails of each set intersecting each other constitute a cell. The size of the grid is determined by the number of cells and the size of each cell and may vary according to the requirements for each application of the storage system.

In one embodiment, the rails comprise a number of longitudinal segments with two edge ridges running along each longitudinal edge of the longitudinal segments and a central ridge running parallel with the edge ridges with the same distance to each of the edge ridges. The area between the ridges forms the tracks for receiving and guiding the wheels of the vehicles. To ensure that two vehicles can pass each other when running on the two tracks in different directions on the same segment, the width of the central ridges may be adapted to the size of the vehicles. For example, the width of the central ridge may be a set distance larger than the distance from the outer edge of the wheels and the outer edge of the vehicle. If the outer edge of the wheels are flush with the vehicle's outer walls, the ridge may have the width of twice the set distance. In this case, if the vehicles are determined to travel with a distance of 4 mm, the ridge should be 4 mm wide.

In the intersection area between the first and second sets of rails there are no ridges in order to ensure the vehicles running freely over the intersections.

In one embodiment, the edge ridges of each intersecting rail are in contact with each other, thus forming a corner ridge. The corner ridges may be rounded to prevent the vehicles to catch at the intersections. The shape of the corner ridges may be semicircular, oval or other smoothed shape.

Other features of the invention are defined in the dependent claims. The invention will now be described in more detail and by reference to the accompanying figures.

Figure 1 illustrates a prior art rail arrangement.

Figure 2 illustrates a rail arrangement according to the invention with double tracks in two directions.

Figure 3 and 4 shows details of the rail arrangement of figure 2.

Figure 5 shows an example of a rail arrangement forming 4x4 cells.

Figure 1 illustrates the rail arrangement of a prior AutoStore® system described above. A first set of parallel rails guide movement of the vehicles in a first direction X across the top of the grid structure, and a second set of parallel rails, arranged perpendicular to the first set, guide movement of the vehicles in a second direction Y, perpendicular to the first direction. In this way, the grid of rails allows movement of the vehicles in two dimensions in the X-Y plane, so that a vehicle can be moved into any desirable position in the grid. In this embodiment the rails in the Y direction has double tracks, thus enabling the vehicles to pass each other. The rails in the X direction, however, have only a single track. This means that the vehicles only can pass each other in the Y direction.

Figure 2 illustrates and embodiment of a rail arrangement 20 according to the invention. Also this arrangement comprises a first set of rails in the X direction and a second set of rails, arranged perpendicular to the first set, in the Y direction.

Elongated elements in the X and Y direction are arranged perpendicular to each other, and the first and second sets are intersecting in "crossroads" 21. In this embodiment, however, the rails in both the X and the Y direction have double tracks, i.e. two parallel tracks adapted for receiving and guiding wheels of the vehicles, thus enabling passage of vehicles both when they drive in the X- and the Y direction.

The double tracks each comprises longitudinal segments with two edge ridges 23, 23 ', 24, 24' running along each longitudinal edge of the longitudinal segments, and a central ridge 25, 25 ' running parallel with the edge ridges with equal distance to each of the edge ridges. The two areas between the ridges are thus forming the two double tracks for receiving and guiding the wheels of the vehicles. In the intersection area/crossroad 21 between the first and second sets of rails there are no ridges.

At each intersection 21 , the edge ridges 23, 23 ', 24, 24' of each intersecting rail are in contact with each other, thus forming a corner ridge 26. The corner ridges are arranged tightly connected in order to prevent the vehicle from snagging to the joints. For the same reason, ie. in order for the vehicles to have a smooth drive across the intersections, the corner ridges are rounded at the insides. The vehicles then experience the corner ridges as a continuous, curved ridge.

Figure 3 and 4 shows details of the rail arrangement of figure 2, comprising a first set of rails 30 in the X direction and a second set of rails 40, arranged perpendicular to the first set, in the Y direction. Figure 3 shows the cross sections A-A and B-B from figure 2, where A-A is in the set of rails in the Y direction and B-B is in the first set of rails in the X direction.

The second set of rails 40 all comprises recess 41 into which the first set of rails 30 may be arranged when making the intersections between the first and second sets of rails. The first set of rails 30 comprises areas 31 where there are no ridges, which are adapted to be arranged coincident with the recesses 41 of the second set of rails, thus providing the intersection areas/crossroad 21 of figure 2. The recesses 41 and crossroads 31 are also present at the corners and intersections at the circumference of the grid, as can be seen in the example of figure 5, which shows an example of a rail arrangement forming a grid with 4x4 cells. As further shown in Fig. 5, the outermost rails of the grid structure intersect at corners. These side elements have an extended end portion free of a center ridge, such that a ridge free portion is provided at the corners of the grid as well.