Electro-conductive flat cable structure

Abstract

 57 An electro-conductive cable structure (a) comprises four sets of leads (1), each set forming a cable (b) and a central steel cable (2). The cable 2 is the sole element which is resistant to tensile stress and acts as the core of the cable structure (a). The cables (b) and the steel cable (2) are held in a mass of isolating material which acts as a lining sleeving. The isolating material forms co-planar units (3) and (3') which are separated from each other by grooves (4).

Description

[0001] This invention relates to an electroconductive flat cable structure which may be used, inter alia, in a vertical transportation system. Such a cable structure may be employed in the power supply intended for the operation of elevators, freight elevators or the like, and also for the lighting, ventilation, etc. In as far as the knowledge of the present art goes, it can be said that there exist electro-conductive flat cable structures having steel cables acting as carrying members located along both sides of the structures. Such cable structures can connect elevators, freight elevators or crane-bridge receptacles with the general supply network.

[0002] When one of these known cable structures is used with an elevator, it generally runs along one of the sides of the elevator cabin and is connected thereto through one or more of the cabin walls.

[0003] Such cable structures are permanently subjected to variable flexural stress and, to a minor degree, variable tensile stress. The stress depends upon the position of the cabin in the up/down direction and the position of the cabin relative to the end of the cable structure remote from the cabin.

[0004] The use of flat cable structures has assisted, to a large extent, the positioning of the cable structure. However, problems have arisen in relation to the steel cables being positioned on the sides of the cable structure. Such problems are caused by lack of equalization of stresses in the two cables, resulting in swinging, warping and other torsional effects, which give rise to different bending radiuses and, consequently, lead to mechanical stress differences between the various electrical leads incorporated in the cable structure.

[0005] One of the most common problems in the known cable structure, wherein the carrying steel cables are mounted within the sides of the-structure, is the difficulty in getting the same or homogenous stress in both carrying cables.

[0006] In fact, said situation causes, in said known cable structure, the twisting thereof with respect to its own geometric longitudinal axis.

[0007] Moreover, said twisting causes the cable structure to shorten and collide with the elevator cabin, often rubbing against it, which often results in the flat cable structure being broken or torn, primarily because of the lack of space which usually exists between the cabin and the sides of the shaft wherein the elevator moves.

[0008] Another negative aspect derived from said distribution of the carrying cables along the sides of the flat cable structure is that, because of the above mentioned twisting, the cable structure is prematurely overstressed and eventually failure occurs. Even if the failure is only partial, it causes the subsequent disabling of the whole cable structure bearing in mind that the leads are intended to channel the power serving different parts of the elevator, such as the operating keys, the alarm, lights, ventilation etc.

[0009] Although the co-planar arrangement of the various electro-conductive leads in single column confers greater flexibility to the flat cable structure, it also markedly increases its width according to the number of electro-conductive leads required.

[0010] This greater width of the cable structure presents the disadvantage of facilitating the twisting thereof because of the reasons above mentioned and, what is worse, it also creats a greater surface resistance to the air generated by the cabin displacement, thereby increasing the space occupied by the cable structure. All these factors increase the tendency from the cable structure to approach the cabin or collide therewith, thus accelerating the destructive process by action of the mechanical friction.

[0011] In order to limit the problems indicated above, flat cable structures have been used which are either of limited length or which are used together with a travel box mounted in the elevator shaft. This makes the use of these known flat cable structures impracticable and their installation extremely expensive.

[0012] It is an object of this invention to provide a new or improved electro-conductive flat cable structure in which the problems mentioned above are overcome or reduced.

[0013] According to this invention there is provided an electro-conductive flat cable structure, said cable structure being of elongate configuration and comprising a sheath forming the lining sleeving of a plurality of longitudinally extending individual leads which are formed into sets separated from each other, characterised in that the cable structure further comprises at least one longitudinally extending flexible member which is mechanically resistant to tensile stress and which acts as the core of the cable structure, said at least one flexible member being located at an intermediate position in relation to said plurality of individual leads so as to be flanked on each side by said leads together with their associated lining sleeving.

[0014] In the cable structure of this invention said at - least one flexible member and the individual leads are co-planar thereby permitting a certain degree of cross-bending of the individual leads.

[0015] Because the individual cables and said at least one flexible member are co-planar and arranged as set out above, the cable structure can be connected directly between the machinery hall and the cabin of an elevator thereby avoiding the use of travel boxes and the resulting high cost of providing such boxes.

[0016] Because the sets of leads are aligned with said at least one flexible member, all of them adopt the same bending radius, thereby avoiding partial rupture of any of them and, as a consequence, the lifetime of the cable structure is considerably extended.

[0017] Preferably, said at least one flexible member is flanked on each side by two sets of leads, the leads of each set being disposed at two different levels with respect to each other relative to the thickness of the cable structure.

[0018] By disposing the individual leads of each set at at least two levels, the width of the cable structure may be reduced thereby avoiding the torsional effects associated with a wide cable structure.

[0019] The leads of each set may be disposed in two columns or in three columns, or in a zig-zag formation, or in a group around an imaginary axis.

[0020] The leads of each set may also be diposed in a group comprising a central lead surrounded by the remaining leads of the group, thete existing gaps between said remaining leads. The provision of gaps improves the flexibility of the cable structure and facilitates virtual movement thereof.

[0021] The provision of disposing the leads of a see around an axis assists in the manufacture of the cable structure by extrusion.

[0022] Said at least one flexible member may be constituted by a cable which coincides with the longitudinal geometrical axis of the cable structure.

[0023] The provision of a single cable acting as the core of the cable structure avoids stress differences between the sides of the cable structure and, as a consequence, the twisting effect which occurs in the prior art cable structure is avoided.

[0024] The provision of a single cable which acts as the core of the cable structure and which is resistant to mechanical stress makes it possible to use longer cable structures. The single cable bears the stress arising both from its own weight and also from the weight of the other part of the cable structure.

[0025] Conveniently, said at least one flexible member and said sets of individual leads are disposed in a longitudinally extending mass of isolating material which forms said sheath, said mass of isolating material having longitudinally extending grooves which define a series of co-planar units joined to each other by material of reduced cross-sectional width, each of said co-planar units containing either a respective one of said sets of leads or said at least one flexible member.

[0026] The sheath formed in this way provides the advantage that it does not permit the cable structure to flicker.

[0027] Preferably, said isolating material comprises an incombustible plastics material. The use of such material makes the cable structure safe in the event of short circuits, sparks, or other factors leading to spotaneous combustion.

[0028] The electro-conductive flat cable structure set out above is suitable for use in any type of vertical transportion system such as high and low speed elevators, freight elevators, crane-bridges etc.

[0029] This invention will now be described in more detail, by way of example, with reference to the drawings in which:-

Figure 1 is a cut-away perspective view of a length of flat cable structure according to one embodiment of this invention and showing sets of aligned leads which flank a central longitudinally extending steel cable; and

Figures 2 to 5 are cross-sectional views of further embodiments of this invention showing alternative arrangements for the sets of leads.

[0030] In all figures, the same reference numerals indicate the same or corresponding parts while sets of elements are indicated by letters, the numerals and letters being as follows:-

[0031] Referring now to Figure 1, the cable structure a comprises four sets of leads 1 which, together with their individual isolating sheaths, form four cables b. The four cables b flank a central zone c in which there is a flexible member in the form of a steel cable 2. The steel cable 2 is the sole element which is mechanically resistant to tensile stress and acts as the core of the cable structure. As may be observed in Figure 1, both the leads 1, and the cable 2 extend longitudinally along the cable structure a.

[0032] Both the steel cable 2 and the cables b formed from the sets of leads 1 together with their individual isolating sheaths are held in a sheath formed from a mass of isolating material and which acts as a lining sleeving. The isolating material is an incombustible plastics material. The isolating material forms co-planar units 3 and 3' which are separated from each other by grooves 4. The grooves 4 reduce the width of the cable structure a and increases its flexibility.

[0033] Within the cable structure a, the stress resistant steel cable 2 coincides with the longitudinal geometrical axis of the cable structure a and is symmetrically flanked by the sets of leads 1 together with their individual isolating sheaths. The set of leads 1 also extend longitudinally along the cable structure a. Although not illustrated, the leads 1 maybe co-planar with each other and with the cable 2 so as to form a single column. Alternatively, the leads 1 in each set may be positioned at at least two different levels with respect to the thickness of cable structure a. This latter arrangement is the more interesting one because it makes it possible to accommodate more leads in the cable structure without increasing its width or to reduce the width of the cable structure without reducing the number of leads. This avoids the problems indicated above.

[0034] In all the illustrated embodiments, the sets of leads 1 are arranged in at least two different levels. Thus, in Figure 1, the leads 1 of each set are arranged in a zig-zag formation, in Figure 2 the leads 1 of each set are arranged in two columns or layers, and in Figure 3 the leads 1 of each set are arranged in three layers or columns. In Figure 4, in each set there are four leads 1 positioned around an imaginary central axis bearing no lead. In Figure 5, the leads 1 form sets disposed in wobbling form. In Figure 6, in each set the leads 1 are arranged in a group comprising a central lead surrounded by the remaining leads, there existing gaps between said remaining leads.

[0035] By arranging the sets of leads so that the leads are disposed at at least two levels, the width of the cable structure a is reduced and its thickness is increased. This reduces the surface area which provides resistance to wind and, consequently, flickering during movement of an elevator to which the cable strucutre is attached. It also reduced the cross-sectional area of the isolating material.

[0036] In order to avoid electric discharges, the cable 2 may be connected to ground by means of copper sleeving which acts as a jacket or sheath for the cable 2 and improves electrical conduction.

[0037] Also, in order to avoid electrical discharges, one of the leads 1 may laid bare and connected to the ground.

[0038] The cable structure a may be extended in a length located in an elevator shaft. Low voltage currents (9 - 12 volts) for the electronic system of the elevator and high voltage currents (220 - 380 volts) for the elevator lighting, alarm ventillation system, door opening system, etc and may flow through such cable structures.

[0039] Cable structures carrying high voltage currents may induce in low voltage cable structure currents of a magnitude similar to the current carried by the low voltage cable structures. This may cause equipment failure.

[0040] In order to avoid this problem, the two cable structures can conveniently be separated from each other by a distance ranging from 20 to 30 cm.

Claims

1. An electro-conductive flat cable structure, said cable structure being of elongate configuration and comprising a sheath (3) forming the lining sleeving of a plurality of longitudinally extending individual leads (1) which are formed into sets separated from each other, characterised in that the cable structure further comprises at least one longitudinally extending flexible member (2) which is mechanically resistant to tensile stress and which acts as the core of the cable structure, said at least one flexible member (2) being located at an intermediate position in relation to said plurality of individual leads (1) so as to be flanked on each side by said leads (1) together with their associated lining sleeving (3).

2. An electro-conductive flat cable structure as claimed in claim 1, characterised in that said at least one flexible member (2) is flanked on each side by two sets of longitudinally extending leads (1), said sets being co-planar with respect to each other and with respect to said at least one flexible member (2).

3. An electro-conductive flat cable structure as claimed in claim 1, characterised in that said at least one flexible member (2) is flanked on each side by two sets of leads (1), the leads (1) of each set being disposed at at least two different levels with respect to each other relative to the thickness of the cable structure.

4. An electro-conductive flat cable structure as claimed in any one of claims 1 to 3, characterised in that said at least one flexible member is constituted by a cable which coincides with the longitudinally geometrical axis of the cable structure.

5. An electro-conductive flat cable structure as claimed in claim 4, characterised in that the cable is grounded.

6. An electro-conductive flat cable structure as claimed in claim 3, characterised in that the leads (1) of each set are disposed in two columns.

7. An electro-conductive flat cable structure as claimed in claim 3, characterised in that the leads (1) of each set are disposed in three columns.

8. An electro-conductive flat cable structure as claimed in claim 3, characterised in that the leads (1) of each set are disposed in a zig-zag formation.

9. An elecro-conductive flat cable structure as claimed in claim 3, characterised in that the leads (1) of each set are disposed in a group around an imaginary central axis.

10. An electro-conductive flat cable structure as claimed in claim 3, characterised in that the leads (1) of each set are arranged in a group comprising a central lead surround by the remaining leads of the group, there existing gaps between said remaining leads.

11. An electro-conductive flat cable structure as claimed in any one of the preceding claims, characterised in that said at least one flexible member (2) and said sets of individual leads (1) are disposed in a longitudinally extending mass (3, 3') of isolating material which forms said sheath (3), said mass of isolating material having longitudinal grooves which define a series of co-planar units joined to each other by material of reduced cross-sectional width, each of said co-planar units containing either a respective one of said sets of leads (1) or said at least one flexible member (2).

12. An electro-conductive flat cable structure as claimed in claim 11, characterised in that said isolating material comprises an incombustible plastics material.

Drawing