CN1031904A

CN1031904A - Cable dielectric

Info

Publication number: CN1031904A
Application number: CN 88106590
Authority: CN
Inventors: 戴维·柯蒂斯
Original assignee: Volex Group PLC
Current assignee: Volex PLC
Priority date: 1987-09-08
Filing date: 1988-09-08
Publication date: 1989-03-22
Also published as: AU2328588A; WO1989002646A1; GB8721072D0

Abstract

A kind of dielectric cable comprises one by internal layer (14) and outer (12) institute conductor surrounded (10).Internal layer extends in vertical sine-shaped mode between skin and conductor, thereby defines the groove of a plurality of identical shaped sealings.This structure is by pushing conductor and inside and outside layer coaxially, and the pressure differential that repeatedly changes between each side of internal layer forms.

Description

Cable dielectric

The present invention relates to the dielectric structure of cable.

The cable of common pattern comprises an inner wire that is surrounded by medium, and medium itself is surrounded by an outer conductor.In a kind of design, medium is to be formed by a plurality of walls that radially extend, and the face of wall is parallel to inner wire, and the medium between them limits the space that is substantially fan shaped cross section.Although thisly manufacture and design economy and electric property is good, it has following such shortcoming, if cable bad and when making moisture enter the space, the reduction of the cable performance that then causes will be not limited to the regional area of damage.For dealing with this situation, many designs have been proposed, comprise the wall that is positioned at along all interval crosscut inner wire axles of cable, so that the longitudinal length in space is restricted.This design relates to additional operation and for making the special equipment of transverse wall, it has increased the expense of product, has limited the scope of the cable dimension that can make economically, and and is not suitable for the high-speed production cable.

The present invention has considered these problems and has made.

According to the present invention, a kind of dielectric structure of cable can be provided, this structure comprise one be parallel to substantially conductor extension and and the skin that separates of conductor, and one substantially with the internal layer that between skin and conductor, extends of word style so that limit the groove (cell) of a plurality of sealings.

In one embodiment of this invention, outer dielectric layer and inner medium layer are extruded around a conductor simultaneously.In extrusion process,, this internal layer is shifted towards conductor or towards outer dielectric layer by adjusting the relative air pressure on each side of internal layer.So can produce the internal layer of taking in a zigzag vertical or sinusoidal waveform trajectory.

All specific embodiments of the present invention illustrate by example with reference to the accompanying drawings, wherein:

Fig. 1 is a longitudinal axis schematic cross-section by coaxial cable;

Fig. 2 is the partial cross section schematic diagram of an explanation in order to the cable of production drawing 1, and

Fig. 3 is the perspective view of its outer brachymemma of cable of a Fig. 1.

Consult Fig. 1 and Fig. 3 of accompanying drawing, cable comprises an inner wire 10, and this inner wire 10 is surrounded by two-layer tubular polyethylene medium.Outer 12 separate with this conductor equably, and internal layer 14 extends along the length of cable, are alternately pasting outer field inner surface and pasting conductor to engage.Near inner wire, define the inside groove 16 of a series of sealings and the water jacket 18 of a series of sealings.Skin is surrounded by the outer conductor of for example braid, and this braid itself is to be wrapped in by crust.These elements are all habitually practised, thereby not shown in the accompanying drawings.

The most handy inner wire 10 two-layer method on every side of pushing simultaneously of dielectric structure is made.By increasing the air pressure of internal layer inboard, this layer is moved to skin contact.Pressure by reducing the internal layer inboard moves to conductor internal layer and contacts to the air pressure that is lower than between internal layer and the skin simultaneously.The variation of pressure can be controlled, so the layout of internal layer is clocklike substantially.In order to obtain good electrical properties, to it would be desirable having as far as possible near periodic structure.As long as each " groove " almost is identical, the true form or the style of each groove have nothing important aspect electric.

Now a kind of manufacture method easily is described with reference to Fig. 2.A pair of coaxial polyethylene pipe 12,14 is squeezed around copper conductor 10 by mould 20.Two pipes all are circular, and outer tube 12 is being supported by drawing-die pipe 22 in vacuum tank during its cooling mutually.(device of this tubulation is very common in coiled pipe and cable industry).

The radius of interior pipe 14 is by controlling in the air pressure at A point place.Be increased to more than the ambient pressure by the pressure with A point place, pipe 14 expands in causing, till touching outer tube 12.Then the pressure with A point place is decreased to below the ambient pressure, and the pipe radius reduces till touching conductor in making.The hole of using for conductor in mould 20 is opened to such an extent that can freely flow into and discharge even as big as the air between pipe and the conductor in making.

Therefore by this way by changing air pressure, can produce and be similar to Fig. 1 and dielectric structure shown in Figure 3 at A point place.The wavelength of interior pipe is controlled by speed and/or frequency, manages 12,14 and pushed by mould 20 under this speed, and the air pressure at A point place changes under this frequency.

The air source comprises an air valve 24 by electrical oscillator 26 controls.Valve 24 is by two air sources, 28,30 air feed, one more than the ambient pressure and one below ambient pressure.The output of valve is with oscillator changing-over between two inputs.

Alternation air source from valve 24 is to be drawn towards mould 20 by conduit 32.

Though in this device, be to flow freely into and freely discharge at the air of 12,14 of inner and outer pipes, if necessary, can control the air pressure between them, for example force it to the pressure between interior pipe 14 and the conductor 10 with anti-phase.

In this embodiment, air is used as the control medium, yet also can adopt handling safety and not influence any gas of cable end properties nocuously.

Use said modules as follows in order to an example of the approximate operating condition of production cable:

1.5 millimeters of diameters of wire

10 millimeters of outer tube diameters

2 millimeters of outer tube thickness

1 millimeter of interior pipe average thickness

10 meters/minute of extrusion speeds

1 hertz of oscillator frequency

The air source of ambient pressure+/-0.4 crust is used with adjuster, with the restraining air mass flow.

The required actual pressure that manufactures a product, depend on to a great extent employing polyvinyl pattern and depend on the operation conditions of extruder.

The example that provides is typical, but the unique size that can make anything but.

Stoping dielectric structure water to enter can be in conjunction with other many medium designs, and the conventional method of 5 grooves for example is possible with the inventive concept of the benefit of utilizing two kinds of technology.

The present invention is not limited to above-mentioned all embodiment, and can make many other change and improvement.

Claims

1, a kind of dielectric structure of cable is characterized in that, this structure comprise one be parallel to substantially conductor extension and and the outer and internal layer that between skin and conductor, extends that separates of conductor with word style substantially so that limit the groove of a plurality of sealings.

2, cable dielectric structure according to claim 1 is characterized in that, wherein the shape of the groove of all sealings is identical substantially.

According to claim 1 or the described cable dielectric structure of claim 2, it is characterized in that 3, wherein internal layer is a sinusoidal shape on vertical, axial cross section.

4, a kind of cable that comprises according to arbitrary above-mentioned described dielectric structure of claim.

5, a kind of method of making dielectric structure according to claim 1, it is characterized in that, this method comprises an outer and internal layer of compress one conductor coaxially, repeatedly change the fluid pressure differential on each side of the internal layer that is extruded, so that internal layer between conductor and skin with the word style by deflection, thereby form the groove of a plurality of sealings.

6, method according to claim 5 is characterized in that, wherein the pressure change on each side of internal layer is in check, and therefore all grooves form identical size substantially.

Therefore according to claim 5 or the described method of claim 6, it is characterized in that 7, wherein the pressure change on each side of internal layer is in check, make internal layer on vertical, axial cross section, have a sinusoidal shape.

8, according to the described method of any claim in the claim 5 to 7, it is characterized in that, wherein the fluid pressure differential on each side of internal layer is by increasing and reduce fluid pressure on the side of internal layer to changing more than the ambient pressure and to get off, and the fluid pressure on the internal layer opposite side is constant substantially.

9, according to the described method of any claim in the claim 5 to 7, it is characterized in that wherein the fluid pressure differential on each side of internal layer is by increasing and reducing the fluid pressure on a side of internal layer and reduce and the fluid pressure that is increased on the internal layer opposite side changes in anti-phase mode.

10, a kind of substantially according to here with reference to the dielectric structure of Fig. 1 in the accompanying drawing and 3 described cables.

11, a kind of substantially according to described in order to make the method for dielectric structure here with reference to the Fig. 2 in the accompanying drawing.