JPH04112480A - Electric heater cable - Google Patents

Abstract

PURPOSE:To provide an electric heater cable which is free from risk of failure occurrence and which can serve in a wide temperature range, by connecting a heat emitting element formed from a braid at the core exposure part and installed alongside a feeder wire. CONSTITUTION:Exposure parts 7 are formed alternately at certain intervals L on two core wires 2, and a connecting piece 6 consisting of a braid is wound on these exposure parts 7. In each connection part 8 a heat emitting element 5 of braid structure is pressed to the core wires 2 and contacted in a plurality of places dottedly or linearly by the mentioned connecting piece 6 to generate electrical connection. Because in this fashion the heat emitting element 5 is connected with each feeder wire 1 in a plurality of places, heat emission in the range is enabled to continue even in case part of a braid element wire goes into severance due to change in the temperature cycle at heat emitting or application of an external force such as bending.

Description

[Detailed Description of the Invention] C. Industrial Field of Application] The present invention is used to heat piping, tanks, etc. by generating heat from a heating element in a cable to prevent internal objects from freezing and to maintain a constant temperature. This relates to electric heating cables used for heating purposes.

[Conventional technology] An example of a conventional electric heating cable of this type is shown in FIG.

In FIG. 9, (1) is a power supply line. (2) are the two core wires of the feeder line (1), (3), (4), (9
) is a coating of insulating material, and (5) is a single resistance wire spirally wound around the coating (4). Normally, the wire diameter of the resistance wire (5) is
AWG (American Wire Gauge)
A number of about 36 to 42 is used. (7) is 8 portions of dew provided alternately on two core wires (2), (8) is a core wire (
2) and the resistance wire (5).

Such electric heating cables are attached to, for example, instrumentation piping in cold regions. When an alternating current voltage is applied to the two core wires (2), each resistance wire (5) connected within the section of the adjacent exposed portion (7) generates heat. The heat generated by each resistance wire (5) heats the instrumentation piping etc. in each zone,
This prevents the fluid flowing inside the pipe from freezing.

[Problems to be Solved by the Invention] As described above, in the conventional electric heating cable, a single resistance wire (5) is spirally wound around the insulating coating of the power supply line (1). Then connect the core wire (2) to the resistance wire (5) or connection point (8).
are alternately connected to each other, and are configured to generate heat when energized. For this reason, when an external force such as a change in temperature cycle or bending is applied when an AC voltage is applied to generate heat, the resistance wire (5) may be disconnected and the disconnection zone may not generate heat. In addition, since the heat generation load associated with the temperature rise when one resistance wire (5) is energized is large,
It is unsuitable for keeping warm in high temperature ranges (50°C or higher).

Furthermore, since the resistance wire (5) is connected to the core wire (2) at the connection point (8), there is a problem that there is a risk of poor contact.

The present invention has been made to solve the problems of the conventional devices as described above, and has realized an electric heating cable that has various advantages such as no change in temperature cycle or disconnection due to external force.

[Means for Solving the Problems] The present invention provides, for example, a two-core feeder line in which core wire exposed portions are formed alternately at intervals, and a core wire exposed portion of the feeder wire is electrically connected to one feeder wire. In this electric heating cable, the heating element is a braided body, and the electric heating cable is equipped with a heating element that insulates the heating element from the power supply line.

In addition, the electric heating cable is provided with connectors that connect one of the power supply lines and the heating element in the exposed core portion by pressure contact at multiple locations.

[Function] The electric heating cable is routed along the piping through which the fluid flows. When the energization switch is turned on, voltage is applied between the two core wires. Then, current flows through the braided heating element, which is electrically connected at multiple points in each exposed part of the core wire.
Joule heat occurs. The Joule heat generated in the braided heating element heats the piping and maintains it at a constant temperature.

[Embodiment] Fig. 1 is an explanatory diagram of the configuration of an embodiment of the present invention, Fig. 2 is an exploded explanatory diagram of a part of Fig. 1, Fig. 3 (A), (B), (
C) is a perspective explanatory view of an embodiment of the fixing member, in which a case where the present invention is applied to an electric heating cable for low to medium temperature (O~50.50~120°C) is illustrated. In FIGS. 1 to 3, parts having the same functions as those in FIG. 9 are given the same reference numerals and some overlap, but will be explained in more detail here.

In FIG. 1, (1) is a power supply line. (2) is the two core wires of the feeder line (1), (3) is an insulator that covers the feeder line (1), and (4) is an insulator for grouping.

For the core wire (2), for example, high-conductivity copper, nickel-plated copper, or silver-plated copper wire is used, and the insulators (3) and (4) are made of heat-resistant fluorine-based resin. used.

(5) is a heating element, and (6) is a connector. The above heating element (5) is a braided structure in which bare resistance wires (50) of about 0.08 to 0.1 diameter are woven in a manner such as "one wire alternately in and out" or "two wires alternately in and out". It consists of In addition, the connector (6) uses a thin wire with high conductivity equivalent to the core wire (2),
Like the heating element (5), it has a braided structure and is formed into a band shape. (7) is the exposed part (second
(see figure), (8) is the connection part between the core wire (2) and the heating element (5). The exposed portions (7) are formed alternately on the two core wires (2) at regular intervals, and a connector (6) made of a braided body is wound around the exposed portions (7). Then, the heating element (5) having a braided structure is pressed against the core wire (2) at each connection part (8) by the connector (6), and is electrically connected by contacting the core wire (2) at multiple points or in a linear manner. . (9) is the connector (
6) is an insulator that covers etc., and (10) is a protective outer covering. Thus, the electric heating cable (C) of the embodiment of the present invention is formed by the above-mentioned power supply line (1), heating element (5), connector 6), etc.
is configured.

The electric heating cable (C) having the above structure is made, for example, as follows.

First, an insulator (3) is layered around a core wire (2) made of a stranded wire such as a silver-plated copper wire to produce a coated conductive wire.

Arrange two of the conductive wires made and use an insulator (4
), and a two-core power supply line (1) with an oval cross section is molded with resin. Next, the outer portion of the insulator 4) around the power supply line (1) is cut out in a semicircular shape alternately at regular intervals. When cut into a semicircular shape, about half of the core wire (2) is exposed, forming an exposed portion (7) of a predetermined width.

After forming the exposed portion (A), a resistance wire is knitted around the power supply line (1), and the heating element (5) is pressed and wrapped around it.

In order to ensure contact between the heating element (5) and the two core wires (2), a braided connector (6) with a width approximately equal to the width of the exposed part (7) is placed at the position of the exposed part (7). ).

Furthermore, when a ring-shaped fixing piece (11) as shown in FIGS. 3(A) to (C) is placed on the opening, the claws (12) of the fixing piece (11) are pressed from both sides. It penetrates into the gap between the strands of the core wire (2) and is fixed. As a result, the heating element (5)
A plurality of wires (50) constituting the core wire (50) are pressure-welded in a point and linear manner, and the heating element (5) contacts the outer periphery of the core wire (2) at multiple locations to be electrically connected. A theoretical connection diagram between the heating element (5) and the core wire (2) is shown in FIG.

As illustrated, the plurality of wires (50) constituting the heating element (5) are connected to the core wire (2) in contact with each other at multiple points. Thereafter, the insulator (9) is molded and covered with resin by extrusion processing, and if necessary, the outermost layer is covered with a protective outer cover (lO) such as a braided fiber or a stainless steel sheath.

FIG. 5 is a configuration explanatory diagram of another embodiment of the present invention. Fifth
In the illustrated embodiment, the structure of the heating element (5) is different from that in FIG.
There are no differences in other parts. Here, the heating element 5) is woven flat using a plurality of strands (50) like "Sanada cord" [Figure 6 (A), (B)
). The flat knitted heating element (5) has an exposed part (
7) is wound spirally around the outside of the insulator (4) of the two-core electric wire. After that, the insulator (9
) is molded and covered with resin, and a protective outer cover (1
0) or covered.

In addition, as shown in FIGS. 7A and 7B, a heating element 5) is formed by knitting strands (50) on a heat-resistant core material (51).

The electric heating cable (C) of the present invention having such a configuration is applied to piping as shown in FIG. 8, for example.

In FIG. 8, (20) is a main pipe through which fluid flows, (21) is a branch pipe, (22) is a heat insulating material provided around a part of the main pipe (20), and (23) is a manual control valve. Further, (24) is a power supply box, and (25) is a terminal for attaching the power supply box (24). The electric heating cable (C) of the present invention is wired along the main pipe (20) as shown in the figure. It is also branched off at a branch path (1a) and wired to a branch pipe (21). Particularly, in parts such as the manual control valve (23),
The wires are densely wired in a folded pattern to enhance heating. When voltage is applied from the power supply box (24), each braided wire (50) of the braided heating element (5) generates heat as described above. As a result, the main pipe (20) and branch pipes (
21) Alternatively, the fluid flowing inside the manual control valve (23) is heated, and the temperature is detected by a temperature sensor (not shown) and controlled to a constant temperature.

In addition, in the above-mentioned example, the case of the braided heating element (5) made of a plurality of resistance wires (50) such as nickel chromium was illustrated, but in addition to this, carbon fiber or carbon fiber may be used. A wire made of ceramic or resin fibers twisted together, or a wire made of ordinary metal resistance wire and carbon fiber may be used. Also, an insulator (3).

(4) and (9) are also not limited to the embodiments, and may be constructed of silica gel fibers, ceramic fibers, or the like. If these insulating materials such as ceramic fibers are used to form a sheath shape, an electric heater suitable for high temperature applications can be provided.

Furthermore, although the case has been described in which an alternating current voltage is applied to two core wires, it may be configured to have three cores and apply three-phase alternating current.

[Effects of the Invention] The present invention provides a power supply line that is coated with insulation and has exposed core parts formed at regular intervals, a heating element that is provided along the power supply line and is connected at the exposed core parts, and is constituted by a braided body; This is an electric heating cable that includes an insulator that surrounds a body and a power supply line.

In addition, an electric heating cable was constructed in which a connector was provided for electrically connecting the heating element to the power supply line at multiple points by press-contacting the heating element at the core wire exposed portion.

As a result, the heating element is connected to each feeder line at multiple points, so even if part of the braided wire breaks due to a change in the temperature cycle during heat generation or when an external force such as bending is applied, the band can be maintained. There is no such thing as not having a fever.

In particular, since a connector is provided for connecting the heating element to the power supply line by pressure contact, there is no possibility of contact failure. In addition, the heat generation load caused by the temperature rise when the heating element is energized is distributed, so it can be used not only in the medium humidity range (50 to 120 degrees Celsius) but also in the high temperature range (120 to 120 degrees Celsius).
It can also be applied to heat retention, etc. In this case, as described above, if a heat-resistant insulating material such as ceramic fiber or polyimide fiber is used in a sheath shape such as Inconel, it can withstand high temperatures.

Therefore, according to the present invention, it is possible to provide an electric heating cable that is free from failure and has a wide applicable temperature range.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of an embodiment of the present invention, Fig. 2 is an exploded explanatory diagram of a part of Fig. 1, and Fig. 3 (A), (B), (
C) is a perspective explanatory diagram of an embodiment of the fixator, FIG. 4 is a theoretical electrical connection diagram of a heating element, FIG. 5 is a configuration explanatory diagram of another embodiment of the present invention, and FIGS. 6 and 7. (A) and (B) are explanatory diagrams of a heating element, FIG. 8 is a detailed explanatory diagram of the present invention, and FIG. 9 is an explanatory diagram of the configuration of a conventional electric heating cable. In the figure, (1) is the feeder line, (2) is the core wire, and (3) is the feeder line. (4), (9) are insulators, (5) are heating elements, (6)
is the connector, (7) is the exposed part, (8) is the connection part, (10)
is the outer cover, (11) is the fixed piece, (12) is the claw, (20) is the main pipe, (21) is the branch pipe, (22) is the insulation material, (23) is the manual control valve, (24) is the power supply The box, (25) is a bunt, (50) is a wire, (51) is a core material, and (C) is an electric heating cable. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A power supply line that is coated with insulation and has exposed core parts formed at regular intervals; a heating element that is provided along the power supply line and is connected at the exposed core parts and is constituted by a braided body; and the heating element and the An electric heating cable comprising a power supply line and an insulator surrounding the power supply line. (2) The electric heating cable according to claim (1), further comprising a connector for press-contacting the heating element to the power supply line in the exposed core portion to electrically connect the heating element at multiple points.