Hoisting device

A hoisting device includes a trolley travelling along a support structure, and a hoisting member to be lowered and lifted therefrom by means of hoisting ropes, as well as a current supply cable between the trolley and the hoisting member, wherein the structure of the current supply cable is made to assume a spiral shape such that in an uplifted position it forms an at least substantially flat-spiral structure wherein turns of the spiral structure lie in turns of increasing diameter.

BACKGROUND OF THE INVENTION

The invention relates to a hoisting device comprising a trolley travelling along a support structure, and a hoisting member to be lowered and lifted therefrom by means of hoisting ropes, as well as a current supply cable between the trolley and the hoisting member.

In prior art, energy transfer has been solved by drum-reeling chains or ladder-type collapsible structures. Twist spiral structures are also known wherein the twists of the spiral are stacked on top of one another, in to the shape of a tubular cylinder, like those of a screw thread. When the hoisting device is used for instance as a pick-up robot embodiment in an automatic warehouse, the known current supply cable structures have caused vibration of the hoisting member, which, in this use in particular where moving takes place in accurately and narrowly dimensioned aisle passages, is undesired. Further, in an upper position of the hoisting member, the drum-reeling and collapsible or superimposable structures require a considerable amount of space above the hoisting member.

SUMMARY OF THE INVENTION

An object of the invention is to eliminate the above disadvantages. This object is achieved by the solution according to the invention, which is characterized in that the structure of the current supply cable is made to assume a spiral shape such that in an uplifted position it forms an at least substantially flat-spiral structure wherein turns of the spiral structure lie in turns of increasing diameter.

The invention is thus based on using a current supply cable which in the upper position of the hoisting member settles in the shape of a flat-spiral structure.

It would be most preferable that all turns of the spiral structure were substantially in the same plane, but an incomplete flat spiral is also possible where the turns of the spiral structure lie in a plurality of planes but where the number of these planes is substantially smaller than that of said turns. The limiting and determining point herein is in how small a space it would be advantageous to place the current supply cable in a height direction.

Preferably, a frame of the current supply cable is made of a material which by means of heating is formed into a flat-spiral structure and which, after the heating, has a memory striving to return an unwound cable in to the shape of the flat-spiral structure. The frame of the current supply cable may be formed for instance from a pneumatic hose by curing it in to the shape of a flat spiral. The necessary wiring, such as electric lines, and preferably also data cable(s), is/are drawn into the frame of the current supply cable after its heating.

The solution according to the invention is less expensive, contains fewer movable parts, requires less space and causes no vibration of the hoisting member. In addition, it enables data transfer cables, which are nowadays necessary in more and more uses, to be installed in the same space as the electric lines, making them all well protected.

This new structure enables the life of the current supply cable to be enhanced so as to last even ten times longer than that in the previous solutions. It is now possible by the same cable to achieve endurance of about 400 000 liftings and lowerings. The new structure is also considerably more inexpensive to implement.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, a hoisting device1according to the invention comprises a trolley3travelling along a support structure2, and a hoisting member5to be lowered and lifted therefrom by means of hoisting ropes4, as well as a current supply cable6between the trolley3and the hoisting member5.

A use of such a hoisting device1is as a pick-up robot in an automatic warehouse, where the structure of the current supply cable6according to the present invention is extremely advantageous.

The (internal) structure of the current supply cable6is made to assume a spiral shape such that in an uplifted position it strives to form a flat-spiral structure wherein preferably all turns of the spiral structure lie substantially in the same plane in turns of increasing diameter. This is not always possible, but the current supply cable6may, in accordance withFIG. 4, also wind up into an incomplete flat spiral where the turns of the spiral structure lie in a plurality of planes but where the number of these planes is considerably smaller than that of said turns.

In the example presently described, the current supply cable6assuming a spiral shape is formed such that a first end r of the current supply cable6, which is closest to a centre line of the spiral structure, is attached up to the trolley3while a second end R, which resides outermost from the centre line of the spiral structure, is attached to the hoisting member5. A portion of the spiral settling and curling on top of plane surface A of the hoisting member5is supported by plane surface A of the hoisting member5as well as by an inner edge of the spiral that has settled earlier, with a slightly larger radius, on plane surface A, an outer edge of the portion of the spiral settling and curling being arranged to be supported against the inner edge.

The frame6aof the current supply cable6(FIG. 3) is made of a material which by means of heating is formed into a flat spiral and which, after the heating, has a memory striving to return an unwound cable in to the shape of the flat spiral. For this purpose, a pneumatic hose, for instance, may preferably be used.

The necessary wiring, such as electric lines7, may be drawn into a passage6bof the frame6aof the current supply cable6after its heating.

When using a pneumatic hose, the pneumatic hose is placed for instance in a mould machined out of aluminium and heated without any cables, such as electric lines7, since they would not withstand a temperature of the order of about 150° C. The heating carried out in the mould leaves no recognizable mark in the pneumatic hose. In practice, the hose does not adopt a molten state but, through heating, “learns” the shape forced thereon by the mould.

The cavity6bof the frame6aof the current supply cable6is also provided with at least one data transfer cable8(for instance an Ethernet cable).

The height of the structure of the flat-spiral structure formed by the current supply cable6is in the order of about 10 to 50 mm while the lifting height of the hoisting device1(the path of the loading member) enabled by the down unwound current supply cable6is of the order of about 5 m.

Upon lowering the hoisting member5of the hoisting device1, the spiral current supply cable6opens up in a downwards expanding circle, providing the necessary transfer chain for electricity and data transfer from the trolley3to the hoisting member5.

Upon lifting the hoisting member5, the current supply cable6becomes wound through its memory of shape into a flat-spiral structure on top of plane surface A of the hoisting member5.

Another implementation of the current supply cable6assuming a spiral shape could be one wherein a spring made of spring steel and bent in to the shape of a spiral is used, installed inside a loose protecting tube together with necessary conductors. This implementation has not been separately shown in the drawings.

The above description of the invention is only intended to illustrate the basic idea of the invention. A person skilled in the art may thus vary its details within the scope of the attached claims. Thus, for instance, the use of the hoisting device according to the invention is not limited to the above-described implementation, but it may also be applied to other uses where the lifting height enables a current supply cable winding up in to the shape of a flat-spiral structure to be used.