GB2040545A

GB2040545A - Current Conductor Cable

Info

Publication number: GB2040545A
Application number: GB7943719A
Authority: GB
Original assignee: Volvo AB
Current assignee: Volvo AB
Priority date: 1978-12-21
Filing date: 1979-12-19
Publication date: 1980-08-28
Also published as: FR2445086A1; DE2951431A1; SE7813174L

Abstract

A liquid-cooled welding current cable comprises a flexible insulating liquid-tight hose (1) in which a plurality of separate electrical conductors (2), each consisting of bunched fine copper wires, are loosely arranged without twisting, so that they are movable transversely relative to each other. The coolant flows freely inside the hose and between the conductors. <IMAGE>

Description

SPECIFICATION Current Conductor Cable The present invention relates to a current conductor cable, especially a welding current cable, according to the preamble to the attached Claim 1.

Requirements placed on cables of this type are, in part, incompatibie. Such a cable must be able to conduct high amperages without power loss, i.e. have low resistance. Also, the cable must not heat up during operation. At the same time the cable must have low weight and be readily flexible. Finally, it must have a long life.

Known cables of the type described above have the flexible metal conductors twisted into a single core or arranged in a certain pattern, and coolant channels are arranged at predetermined locations around the conductors. The purpose of the present invention is to provide a current conductor cable which is lighter and more flexible than known cables without sacrificing conductivity, temperature stability or length of life. The concept on which the invention is based is the improvement of the cooling of the individual conductors, and a cable according to the invention has the characterisics disclosed in Claim 1. The individual conductors are loosely arranged in the surrounding hose, essentially without being twined, or else twined with a very long pitch.

Preferably, the conductors are drawn without mechanical tension between the terminals and thus lie "limp" in the hose. With this cable construction, the coolant, water for example, or another cooling liquid, can flow along the conductors in good contact with all of the surfaces of the same. The cooling function is further enhanced by the fact that the separate conductors move in relation to each other at every current pulse passing through the cable, thus improving the washing action of the coolant, a type of "pumping action".

In order for the metal conductors to be able to move freely laterally and for the coolant to wash unimpeded over all of the surfaces of the conductors, according to a further development of the invention, the ratio between the total area of the coolant channels and the total area of the metal conductors should exceed 1:2 and preferably be 1:1-1:0.75.

One embodiment of the invention is described below in more detail with reference to the accompanying drawing, in which Fig. 1 shows a cross section through a welding current cable, and Fig. 2 shows a longitudinal section through one end of the welding current cable according to Fig.

1; The welding current cable shown in Figs. 1 and 2 has an outer casing in the form of an electrically insulating, flexible rubber hose 1. Inside the hose there are a plurality of separate conductors 2.

Each conductor 2 consists of a number of bunched fine copper wires. The conductors 2 are arranged inside the hose 1 without twisting or are twisted with a long pitch (about 100 cm), so that they lie essentially parallel to each other. The ends of the conductors 2 are fixed to terminals 3 at each end of the hose 1. The hose 1 is slipped onto one end of the terminal 3 and is sealingly tightened against the same by means of a clamping ring 4. The terminal 3 is made as a sleeve, and the conductors 2 are clamped fast in the closed end 5 of the sleeve 3. The closed sleeve end 5 is provided on the outside with a lug 6. The sleeve 3 has a through-hole 7 for supplying or removing coolant.

The conductors 2 can be overlong, i.e. be somewhat longer than the distance between the bottoms 5 of the two terminals 3. The conductors 2 will thereby lie loosely in the hose 1 and be able to move laterally in relation to each other as a result of the forces created when current pulses pass through the conductors, thereby making a pumping movement. The conductors 2 thus do not assume a predetermined position relative to each other in the hose 1 nor do they assume a predetermined position relative to the inner circumference of the hose. Thus there are no exactly defined coolant channels within the hose 1. Rather, the coolant is allowed to pass freely around all of the surfaces of the conductors 2.

Very effective cooling of all of the conductor surfaces is achieved in this manner since the conductors move relative to each other in operation, both as a result of the bending of the hose and the pumping movement just mentioned.

The conductors 2 are thus also relieved of mechanical load: the supporting mechanical function of the cable is taken over by the hose 1.

The copper conductors 2 thus do not completely fill up the interior of the hose 1. The ratio between the cross-sectional area available to the coolant and the total area of the copper conductors 2 should be greater than 1:2. A ratio of 1:1 has been shown to be suitable even if lower ratios down to 1:1.5 and higher ratios up to 1:0.75 can be used in certain applications depending on, for example, the desired amperage and the intermittance factor of the current pulses.

In the example described above, water is used as a coolant. Within the scope of the invention, however, other coolants can also be used, both liquid and gas.

The attached drawing and the above description relate to a cable with one single cable part. The scope of the invention also encompasses cables with several cable parts. For example, several cable parts can be intertwined with a short pitch (20--50 cm) and be held together with an outer, flexible cover of rubber or plastic, for example. This cover can be reinforced to guard against wear. Inside the cover, the cable parts can be potted in lubricant. A coaxial design is also conceivable, in which a thicker cable part is arranged in the center and is surrounded by thinner cable parts with short pitch around the thicker cable part. In this case as well the cable parts are enclosed in a cover.

Claims

1. Cooled current conducting cable for high amperages, especially a water-cooled welding current cable, which'has at least one cable part comprising a plurality of flexible metal conductors; a flexible, insulating casing surrounding the conductors, an electric terminal joined to the conductors at each end of the casing; and longitudinal coolant channels arranged within the casing; characterized in that the metal conductors along at least the major portion of their length lie loose in a hose, forming the casing, of flexible, insulating material which is impermeable to the coolant, so that the conductors are easily transversely movable in relation to each other and in relation to the hose, especially under the influence of current pulses conducted through the cable parts, whereby the coolant channels are formed of the changing spaces between the conductors and the hose and between the conductors themseives.

2. Cable according to Claim 1, characterized in that the conductors are arranged without mechanical tension between the two terminals of the cable part so that the conductors are mechanically relieved and the hose assumes the essential supporting mechanical function of the cable part.

3. Cable according to Claim 1 or 2, characterized in that the ratio between the total area of the coolant channels and the total area of the metal conductors of the cable part is greater than 1:2, suitably 1:1.5 and preferably 1:11:0.75.

4. Cable according to one or more of Claims 1-3, characterized in that each metal conductor is formed of a plurality of bunched (twisted) thin metal wires.

5. Cable according to one or more of Claims 4, characterized in that the cable comprises several cable parts twisted together with a common pitch and held together by an outer, flexible cover.

6. Cable according to one or more of Claims 1-4, characterized in that the cable comprises several cable parts of which a thicker part is arranged centrally and the rest are twisted with a common pitch around the central cable part, the cable parts being held together by an outer, flexible cover.

7. Cooled current conducting cable for high amperages substantially as hereinbefore described with reference to and as shown in the accompanying drawing