JP2955953B2 - Heating tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention causes an electric heating element provided outside a tube to generate heat, heats a fluid in the tube, and keeps the temperature of the internal fluid constant. It relates to a heating tube used in such a case.

2. Description of the Related Art A conventional heating tube of this type is, for example, an apparatus described in JP-A-51-22140. FIGS. 3A and 3B show a tubular heater described in Japanese Patent Application Laid-Open No. 51-22140.

In FIG. 3 (A), (10) is a composite tube, (11) is a sampling tube, (12) is a heating element, (13) is a control layer, (14) is a heat shield layer, and (15) is a jacket. (16) is a moisture-proof layer. An enlarged sectional view of the heating element (12) is shown in FIG. (B) In the figure, (17) is a conductive particle,
(18) is a web of a polymer substance in which conductive particles (17) are dispersed and arranged, and (19) and (20) are webs embedded in the web (18).
The book conductor, (21) is a jacket. The web (18) has a self-control characteristic in which the electric resistance has a positive temperature gradient, and the resistance increases in response to the rise in temperature to keep the temperature at a constant value.

Conductors (19), (20) in such a composite pipe (10)
Is connected to a power source, and current flows from one line of the conductors (19) and (20) to the other line via the web (18), and the temperature of the web (18) rises. Web (18) is sampling tube (11)
The heat generated in the web (18) moves to the sampling tube (11) so that the transfer fluid such as gas and liquid inside is maintained at a constant temperature.

[Problems to be Solved by the Invention] As described above, a conventional heating tube (1) uses a web (18) of a polymer substance in which conductive particles (17) are dispersed and arranged as a heating element (12). I have. The conductors (19) and (20) are electrically connected via the web (18), and the web (18) is configured to generate heat when energized.

On the other hand, when an external force is applied to the composite pipe (10), tension acts on the bending stress of the web (18). The tensioned web (18) has an increased electrical resistance and a reduced calorific value.
As a result, when the sampling tube (11) is bent,
When the web (18) is wound around the sampling tube (11) in order to make the heat transfer uniform, when the tube diameter is small, there is a problem that the heating amount is remarkably reduced.

The present invention has been made in order to solve the above-described problems of the conventional apparatus, and has realized a heating tube having various advantages such that the heat generation amount is not affected by a construction state.

In the present invention, the web of the above-mentioned polymer substance (18)
A substance having a self-control characteristic as described above is referred to as a “semiconductive heat body”.

Means for Solving the Problems The present invention relates to a tube through which a fluid flows, a feed line composed of two or three bare core wires provided in the length direction outside the tube, and a feed line and the tube. An eccentric heating element wrapped around a plurality of fibrous semiconductive heating elements and knitted;
The heating tube includes an insulated heating element and an insulating coating surrounding the power supply line.

[Operation] A heating tube is connected to, for example, a flow path through which a fluid flows. When the power switch is turned on, a voltage is applied to the power supply line. Then, current flows through the braided heating element electrically connected at multiple points via the core wire of the power supply line,
Joule heat is generated. Joule heat generated in the braided heating element heats the tube, is transmitted to the fluid flowing inside, and is maintained at a constant temperature.

[Embodiment] FIG. 1 is an explanatory view of the configuration of an embodiment of the present invention, and FIG. 2 is a principle electrical connection diagram of the embodiment of the present invention.

In FIG. 1, (1) is a heating tube,
(2) is a tube embedded in the heating tube (1). Tube (2) is a synthetic resin tube,
A metal pipe or the like whose outer periphery is insulated with a thin layer is used.
(3) is a power supply line, and (4) is two core wires constituting the power supply line (3). The core wire (4) is made of a material having high conductivity, such as copper, nickel plating of copper, or silver plating of copper. Is used. Two core wires (4)
Is wound around the tube (2) with a loose spiral.

(5) is an unbalanced heating element, and (50) is its element wire. As described above, the eccentric heating element (5) is made of an organic semiconductive substance having a positive temperature gradient and a self-control characteristic with an electric resistance of 0.1.
The element wire (50) is formed into a fibrous shape of about 1.0 mmφ. Then, the wire (50) is wrapped around the tube (2) along which the power supply line (3) is extended, so that "one alternately enters and exits" or "2.
A braided heating element (5) is constructed by knitting in "alternate entry / exit", etc. (6) is an insulating coating, which is made of an insulating material having corrosion resistance and heat insulation such as fluororesin. The element wire (50) of the conductive heating element is electrically connected to the two core wires (4) in a point or linear manner at many points by the insulating coating (6).

The heating tube (1) having the above configuration is
For example, it is made as follows.

First, two strip-shaped bare core wires (4) made of silver-plated copper or the like in the power supply line (3) are wrapped around the tube (2) at a distance of about 180 degrees with a weak spiral. Next, the braided heating element (5) is formed by braiding a plurality of element wires (50) of a semiconductive heating element so as to wrap around the tube (1) around which the power supply line (3) is wound. .
After the braided heating element (5) is braided, an insulating coating (6) is formed on the outer periphery of the braided heating element (5) by, for example, extrusion molding so as to cover the fluororesin with a substantially uniform thickness. As a result, the plurality of strands (50) constituting the eccentric heating element (5) are pressed against the two bare core wires (4), and the eccentric heating element (5) is connected to the core wire (4).
At a plurality of places and electrically connected to the outer periphery.
FIG. 2 shows a principle electrical connection diagram between the eccentric heating element (5) and the core wire (4). As shown in the figure, a plurality of strands (50) constituting the unbalanced heating element (5) are connected to each other at intersections of the mesh, and a large number of resistors r are provided between the two core wires (4). Are connected in a matrix to form a parallel circuit of the resistance R over the entire length of the tube (2) and the feed line (2).

The heating tube (1) having such a configuration is used as an electric heating / insulating conduit for gas analysis or liquid for keeping temperature. In addition, as a medical tube, it is also piped to a medical instrument or the like. When a voltage is applied to the power supply line (3) of the heating tube (1), electric current flows to the braided heating element (5) through the two core wires (4), and Joule heat is generated. Joule heat generated in the braided heating element (5) is transmitted to the tube (2), and the liquid or gas inside the tube (2) is heated or maintained at a constant temperature.

In the above-described embodiment, the case where the single tube (2) is heated by the braided heating element (5) has been described as an example. However, a plurality of tubes (2) may be heated together. Also,
Although the case where the element wire of a semiconductive heating element made of a polymer material in which conductive particles are dispersed and arranged is used has been described as an example, carbon fiber or a combination of carbon fiber and ceramic or resin fiber may be used. Further, the case where an AC voltage is applied to the two core wires has been described. However, a configuration may be adopted in which three cores are used to apply a three-phase AC, or a dummy core wire may be provided in the middle.

[Effects of the Invention] The present invention provides a tube through which a fluid flows, a feed line composed of two or three bare core wires provided in the length direction outside the tube, and a plurality of fibers formed by connecting the feed line and the tube to a plurality of fibers. An eccentric heating element wrapped and knitted around a semi-conductive heating element strand,
A heating tube provided with an insulated heating element and an insulating coating surrounding the power supply line was constructed.

As a result, since the heating element has an eccentric structure, when an external force is applied, the eccentric heating element disperses the tension. For this reason, the change in the resistance value due to the tension is reduced, and the calorific value does not decrease as in the conventional resin-like semiconductive heating element, so that the heat retention of the small-diameter pipe is hindered. There are few things. In addition, since the heating element is formed in an unbalanced structure, there is no possibility of strong disconnection against bending stress. what if,
Even if a part of the wire breaks, another wire takes over the shoulder, so that there is almost no effect on heat generation.

Therefore, according to the present invention, construction is convenient without failure,
Moreover, a heating tube with high heating efficiency can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a configuration of an embodiment of the present invention, FIG. 2 is a principle electrical connection diagram of an embodiment of the present invention, and FIGS. 3A and 3B are explanatory views of a configuration of a conventional heating tube. is there. In FIGS. 1 and 2, (1) is a heating tube,
(2) tube, (3) feeder, (4) core,
(5) is an eccentric heating element, (6) is an insulating coating, and (50) is a strand.

Claims (1)

(57) [Claims] 1. A tube through which a fluid flows, a feed line composed of two or three bare core wires provided in a length direction outside the tube, and a plurality of fibrous wires formed by the feed line and the tube. A heating tube, comprising: an unbalanced heating element wrapped and braided by the semiconductive heating element element wires; and an insulating coating surrounding the unbalanced heating element and the power supply line.