JPS62139209A - Special heat resistant cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a special heat-resistant cable suitable for investigating underground resources.

[Conventional technology]

In recent years, the development of technology that utilizes geothermal energy has been attracting attention as a means of utilizing underground resources.

In this case, the heat source investigation target will be a polling survey centered on volcanic areas, but at the same time as the underground geological structure, the trend of underground hot water, the crust of high-temperature rock bodies, the presence or absence of geothermal gas, etc. will be detected. Therefore, it is necessary to hang various measuring instruments and cables several thousand meters deep underground.

Figure 2 is a diagram showing an example of such an investigation situation, in which sensor B connected to the tip of investigation cable C is pulled out from cable drum D for observation well H of several thousand meters polled from the ground, and It hangs down into the observation well H via rollers R1 and R2, and investigates the temperature, hot water, gas, etc. at each point underground.

In this case, the survey cable C is several thousand meters long, and must have tensile strength to withstand its own weight and flexibility to withstand bending, but especially since the crustal structure is several thousand meters underground in a volcanic region, They will be exposed to high-temperature rocks, hot water, corrosive gases, etc.

Therefore, in the conventional survey cable C, multiple signal wires coated with a heat-resistant insulation coating such as 47-fluoroethylene resin are twisted together around the central tensile strength wire using cotton thread or other intervening material, and the outer periphery is Previously, galvanized steel wire was used, but as geothermal development
Regardless of when searching for a heat source of about ℃ 300 to 35
When the target of investigation is gas, water vapor, etc. at 0℃, the cotton threads placed around the signal wires will be carbonized by the heat, and the shape of the support material will be distorted, as shown in P in Figure 3. As a result, the outer diameter and shape of the signal wire assembly are deformed, and as a result, the exterior steel wires A become untwisted. Furthermore, if this untwisting becomes even more severe due to the work of winding up and hanging the cable, there is a problem in that it may lead to a disconnection accident.

[Problem that the invention seeks to solve]

For this reason, when heat-resistant glass fiber was used as the material for intervening signal lines, such as cotton thread, it showed excellent heat resistance and corrosion resistance against gases, etc., but the temperature still exceeded 300°C. When used in a harsh operating environment and in a narrow observation well, the glass 9J1 and A fibers may be separated into pieces due to bending of the investigation cable, resulting in a change in the outer diameter of the cable and damage to the outer steel wire. Twisting collapse occurs and the steel wire breaks, which in turn leads to cable breakage.

The present invention was made in view of these problems, and it is an object of the present invention to provide a special heat-resistant cable that exhibits excellent properties in all conditions such as heat resistance, corrosion resistance, and bending resistance.

[Means for solving problems]

In the special heat-resistant cable of the present invention, when the signal wires are twisted together, a signal wire assembly is formed using carbon fiber as an intervening material, and the cable is provided with at least one layer of sheathing.

[Effect]

Carbon fiber is heat resistant and corrosion resistant, as described below.

Because it has excellent bending resistance, it protects the signal line from high temperatures even when hanging into an observation well several thousand meters underground, maintains good mechanical properties of the cable, and has an electrical shielding effect. It is possible to reduce the amount of noise mixed in.

〔Example〕

FIG. 1 shows a cross-sectional structure of an embodiment of the special heat-resistant cable of the present invention, in which 1 located in the center is a central tensile strength line that particularly strengthens the tensile strength of the signal line assembly, 2a, 2b,
2c, . . . 2f indicate six signal lines twisted around the central tensile line, and these signal lines 2a, 2b,
A heat-resistant insulating coating 3.3 made of tetrafluoroethylene resin (for example, trade name: Teflon) is applied to the outer periphery of 2c, . . . 2f. And each signal line 2a, 2b
, 2c.

. . . The gap 2f is filled with carbon fibers 4 as an intervening material, and further fixed with a coating layer 5 of tetrafluoroethylene resin to form a signal line assembly.

The outer periphery of this signal wire assembly is galvanized steel wire or 5
Two layers of tensile strength wires 6.7 made of alloys such as US31B (JIS standard) and 5US304 are twisted together to protect the cable and add tensile strength.

As previously proposed by the applicant, this double armor wire has an alternately twisted double armor (S-Z twist) to eliminate twisting when tensile force is applied, and to make the exterior clearance equal to the interior clearance. It is preferable to prevent the tensile strength line from protruding by making it larger (Utility Application No. 57-8)
No. 234) As is well known, carbon fiber has heat resistance,
It has excellent corrosion resistance, for example, 4
The strength retention rate hardly changes even after being left for 8 hours.

Further, the strength retention rate after being left in 50% sulfuric acid or 50% caustic soda solution at a temperature of 80° C. for 7 days is also 80% or more.

The following table simply shows the superiority and inferiority of carbon fiber and other intervening materials (glass fiber, cotton yarn) in terms of ox.

From this table, it can be understood that carbon fiber can be
It is superior to glass fiber #I) in all aspects, and in particular, its conductivity is 2.0 x 10Ω/cm3, so it exhibits an electrostatic shielding effect and improves the noise resistance of the cable. It also has the advantage of being able to

It is preferable that the signal lines 2a, 2b, 2c, .

Since the special heat-resistant cable of the present invention has the structure described above, the signal lines 2a and 2b.

2c,...2f have sufficient heat resistance against high heat due to the heat-resistant Teflon insulation coating, and
Since the intervening material that protects the signal lines 2a, 2b, 2c, . . . 2f and forms the signal line assembly is made of carbon fiber, there is no risk of carbonization even at high temperatures. , and bending resistance of carbon fiber: I-... If the shape of the signal line assembly does not collapse due to curvature,
It has the effect of "I".

In addition, since carbon #1lfI11 is conductive, it exhibits a shielding effect for the signal lines 2a, 2b, 2c, . . . 2f, so crosstalk between the signal lines can be prevented. , it can have an excellent effect of shutting out electrostatic noise applied from the outside.

Furthermore, since it is corrosion resistant and has higher tensile strength than glass fiber, it can also have high mechanical properties as a signal cable.

Note that although six signal lines are shown, it goes without saying that the number can be arbitrary depending on the data to be measured.

〔Effect of the invention〕

As explained above, the special heat-resistant cable of this invention is
Heat-resistant tetrafluoroethylene is used as the insulating coating for each signal line, and carbon fiber is used as the intervening material. Even under these conditions, there is no deterioration of the material due to carbonization, and it can stably function as a support material even against corrosive gases. Therefore, it is possible to prevent the outer shape of the cable from being distorted and the outer wires to become untwisted, thereby preventing failures such as wire breakage. Furthermore, since carbon fiber has conductivity, it has the advantage of having a shielding effect against underground noise leaking from the outer wall of an observation well, etc., and improving the resolution of observation data.

[Brief explanation of drawings]

FIG. 1 is a front view showing the cross-sectional structure of the special heat-resistant cable of the present invention, FIG. 2 is an explanatory view showing how the special heat-resistant cable is used, and FIG. 3 is an explanatory view of the cable deformed by carbonization or the like. In the figure, 1 is the center tensile strength line, 2a, 2b, 2c. ...2f is a signal line, 3, 3 is a heat-resistant insulation coating, 4
5 shows the carbon fiber as a supporting material, 5 shows the coating layer, and 6 and 7 show the tensile strength lines of the exterior. Ifr side view of fr heat treatment carpul Figure 1 Figure 3

Claims (1)

[Claims] Two or more signal wires made of stranded or single core wires with a heat-resistant insulation coating are twisted together, the outer periphery of the signal wire is covered with a heat-resistant material, and the outer periphery is covered with at least one layer of tensile strength wire. A special heat-resistant cable characterized in that, in the sheathed cable, carbon fibers are filled in the gaps between the twisted signal wires.