JP2021136108A - Micro heater - Google Patents

Abstract

To provide a micro heater capable of increasing durability of a joint part of a heating wire and a non-heating wire, increasing a filling density of a heat resistance insulation material, and preventing deterioration of a voltage resistance characteristic.SOLUTION: A heating wire 3 is extended from an end part 2a of a metal sheath pipe 2 of a heating part 10 by a predetermined length, and an external peripheral face 30 in a predetermined region reaching at least a tip of an extended part 3a provides a metal sleeve 6. An end part 6a on the side opposite to the end part on the side opposite to the metal sheath pipe of the sleeve 6 is jointed to an end part 5b of a non-heating wire 5. At least one part on the jointed side of the extended part 3a of the heating wire 3, the sleeve 6, and the non-heating wire 5 is housed in a cylindrical metal coated pipe 7 connected to the end part 2a of the metal sheath pipe, and a heat resistance insulation material 8 is filled in a gap in the metal coated pipe 7. Thus, a region where the sleeve 6 of the metal coated pipe 7 and the non-heating wire 5 are positioned is structured as a non-heating part 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a microheater in which a non-heating portion is provided in a series in the axial direction at an end portion of the heating portion.

Conventionally, this type of microheater has a heat generating portion in which a heating wire is housed in a metal sheath tube and a heat-resistant insulating material is filled in a gap, and the heating wire is emitted from the end of the metal sheath tube of this heat generating portion. A non-heating wire is joined to the extended portion by butt welding, and the extending portion of the heating wire and the non-heating wire are housed in a tubular metal cladding tube connected to the end of the metal sheath tube. However, there is provided a non-heat-generating portion in which a heat-resistant insulating material is filled in the gap (see, for example, Patent Document 1).

Patent Document 1 shows a heating wire and a non-heating wire having substantially the same diameter, and butt welding. However, in reality, the heating wire and the non-heating wire have different diameters, and in particular, the non-heating wire side is often relatively thick (the heating wire side is thin). The heating wire is required to be thin, whereas the non-heating wire is vulnerable to heat, and as a result, it tends to be relatively thicker than the heating wire.

FIG. 2 is a cross-sectional view showing a specific structure of a connecting portion between a heat generating portion and a non-heating portion of such a sheath heater. In the heat generating portion 10, the heating wire 3 is housed in the metal sheath tube 2, and the gap is filled with the heat resistant insulating material 4. A heating wire extends from the end 2a of the metal sheath tube 2, and a relatively thick non-heating wire 5 is joined to the end by butt welding. A large step portion 102 is formed at the welded joint portion 12 between the thin heating wire 3 and the thick non-heating wire 5.

The extending portion 3a of the heating wire and the non-heating wire 5 are housed in a tubular metal cladding tube 7 connected to the end portion 2a of the metal sheath tube, and the gap is filled with the heat-resistant insulating material 8. There is. In order to accommodate the thick non-heating wire 5, the inner diameter of the metal cladding tube 7 is larger than the outer diameter of the metal sheath tube 2, and bushings 9 are interposed at the connecting portions. Then, in order to increase the packing density of the filled heat-resistant insulating material 8, the diameter of the metal cladding tube 7 is reduced by pressure by dice pulling or aging.

By the way, due to heating-cooling during use of the microheater, thermal stress is generated in the welded joint 12 between the heating wire and the non-heating wire based on the difference in thermal expansion between the heating wire and the non-heating wire. When heating and cooling are repeated, the joint may break due to the thermal strain caused by this thermal stress, leading to disconnection. Further, depending on the shape of the end of the bushing 9 inside the metal cladding tube 7, the heat-resistant insulating material 8 is sufficient in the gap between the inner peripheral surface of the metal cladding tube 7 and the outer peripheral surface of the metal sheath tube 2 even by the pressure reduction. In some cases, it was difficult to fill the metal, the insulation was insufficient, and the withstand voltage characteristics deteriorated.

Jitsukosho No. 48-38599

Therefore, what the present invention seeks to solve in view of the above situation is that the durability of the joint between the heating wire and the non-heating wire can be increased, and the packing density of the heat-resistant insulating material can be increased. The point is to provide the ability to prevent deterioration of withstand voltage characteristics.

As a result of diligent studies in view of the current situation, the present inventor has found that the reason for the conventional problem is that the conventional microheater has a thin heating wire, so that it is difficult to join with a non-heating wire by welding or the like, and the joining area is also large. Insufficient removal, as a result, there is a limit to increasing the strength of the joint against thermal strain, and the amount of heat-resistant insulating material filled between the thin heating wire and the metal cladding tube is large. Since it is larger than the amount filled between the metal sheath tube and the metal cladding tube, the compression filling of the heat generating portion becomes weaker, the compression filling near the end of the metal sheath tube becomes weaker, and the heating wire We have found that the above problems can be solved by attaching a sleeve to the outer peripheral surface of the extending portion and connecting the sleeve to a non-heating wire, and completed the present invention.

That is, the present invention includes the following inventions.
(1) A heating wire is housed in a metal sheath tube and has a heating portion in which a heat-resistant insulating material is filled in a gap, and the end of the heating portion is composed of a non-heating wire thicker than the heating wire. A microheater in which non-heating portions are continuously provided in the axial direction, and a heating wire extends a predetermined length from the end of the metal sheath tube of the heating portion, and at least at the tip of the extending portion. A metal sleeve is attached to the outer peripheral surface of the predetermined region, and the end of the sleeve opposite to the end of the sleeve facing the metal sheath tube is joined to the end of the non-heating wire. The extending portion of the heating wire, the sleeve, and at least a part of the non-heating wire on the joined side are housed in a tubular metal cladding tube connected to the end of the metal sheath tube. At the same time, the gap in the metal cladding tube is filled with a heat-resistant insulating material, whereby the region where the sleeve and the non-heating wire of the metal cladding tube are located is configured as the non-heating portion. Characterized micro heater.

(2) The non-heating wire is a metal wire or a metal rod, and the opposite end of the sleeve and the end of the non-heating wire are welded and joined in a coaxially abutted state. 1) The microheater described.

(3) The microheater according to (1) or (2), wherein the metal cladding tube is pressure-reduced together with the sleeve and the non-heating wire inside.

(4) The metal cladding tube is connected to the outer peripheral surface of the metal sheath tube via a bushing, and is formed by the bushing, the inner peripheral surface of the metal cladding tube, and the outer peripheral surface reaching the end surface of the metal sheath tube. The microheater according to any one of (1) to (3), wherein a spacer material that fills the surplus space is interposed in the enclosed surplus space.

According to the microheater according to the present invention as described above, the sleeve thicker than the heating wire and the non-heating wire can be firmly joined by welding, the joining area can be increased, and the joining strength can be increased. .. Further, since the sleeve portion is a non-heating portion, the thermal strain itself generated in the joint portion can be reduced as compared with the conventional case, and the durability of the joint portion is further improved. Further, due to the presence of the sleeve, the heat-resistant insulating material on the heating wire side can be sufficiently compressed and filled, and the heat-resistant insulating material can be sufficiently compressed and filled on the end side of the metal sheath tube of the heat generating portion. Even if a gap is created between the outer peripheral surface of the metal sheath tube and the inner peripheral surface of the metal cladding tube 7 due to the shape of the bushing, the heat-resistant insulating material can be sufficiently filled in the gap, and the withstand voltage characteristics are deteriorated. Can be prevented.

In particular, if the excess space surrounded by the bushing, the inner peripheral surface of the metal cladding tube, and the outer peripheral surface leading to the end surface of the metal sheath tube is interspersed with a spacer material that fills the space, the heat-resistant insulating material is more sufficient. Can be filled in, and deterioration of withstand voltage characteristics can be prevented more reliably.

The vertical sectional view which shows the microheater which concerns on the typical embodiment of this invention. A vertical cross-sectional view showing a conventional microheater.

Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the microheater 1 of the present invention has a heat generating portion 10 in which a heating wire 3 is housed in a metal sheath tube 2 and a heat-resistant insulating material 4 is filled in a gap, and the heat generation is generated. A non-heating portion 11 composed of a non-heating wire 5 thicker than the heating wire 3 is connected to the end portion 10a of the portion 10 in the axial direction. As each material of the metal sheath tube 2, the heating wire 3, the non-heating wire 5, and the heat-resistant insulating material 4, the same materials as those conventionally known can be widely used, and the heating wire 3 has an electric resistance value. A nichrome wire or the like that generates Joule heat by energizing a large amount is preferable, and nickel, copper, stainless steel or the like having a small electric resistance value is suitable for the non-heating wire 5.

A heating wire 3 extends from the end 2a of the metal sheath tube 2 of the heat generating portion 10 by a predetermined length, and a metal having a small electric resistance value is formed on an outer peripheral surface 30 of a predetermined region reaching at least the tip of the extending portion 3a. A sleeve 6 made of metal is attached. The end portion 6a of the sleeve 6 on the side opposite to the end portion 6b on the side facing the metal sheath tube 2 is joined to the end portion 5b of the non-heating wire 5.

Here, the non-heating wire 5 is a metal wire or a metal rod such as a metal screw rod, and the tip (end 6a) of the sleeve 6 and the end 5b of the non-heating wire 5 are coaxially abutted against each other. It is preferably welded. Reference numeral 12 is a welded joint. Such welding joining of the sleeve 6 and the non-heating wire 5 can increase the joining area, facilitate the welding work, and have high bonding strength as compared with the conventional welding joining of the heating wire and the non-heating wire. It can be a durable joint.

The extending portion 3a of the heating wire 3, the sleeve 6, and at least the portion of the non-heating wire 5 on the side to be welded are a tubular metal cladding tube connected to the end portion 2a of the metal sheath tube 2 on the heating side. It is housed in the metal cladding tube 7, and the gap inside the metal cladding tube 7 is filled with the heat-resistant insulating material 8. The non-heating wire 5 may be partially housed by the metal cladding tube 7 or may be completely housed.

The diameter of the metal cladding tube 7 is reduced by pressure together with the sleeve 6 and the non-heating wire 5 inside, and the heat resistant insulating material 8 inside is compressed and filled by the pressure reduction, and the sleeve 6 inside is inside. It is in close contact with the outer peripheral surface 30 of the extending portion 3a of the heating wire 3. In this way, the sleeve 6 made of the non-heating material is brought into close contact with the outer peripheral surface 30 of the extending portion 3a of the heating wire, so that the sleeve side outside the inner heating wire 3 is energized and the outer peripheral surface 30 of the heating wire 3 is energized. Since the region where is located is the region of the non-heating portion 11, both sides sandwiching the welded joint 12 become non-heat-generating portions, and the thermal strain generated in the welded joint 12 can be suppressed to a small value, and the joint portion is broken or the like. Can be prevented more reliably.

The metal cladding tube 7 is connected to the outer peripheral surface of the end portion of the metal sheath tube 2 via a bushing 9. Further, a spacer material 13 that fills the space is interposed in the surplus space surrounded by the bushing 9, the inner peripheral surface 71 of the metal cladding tube 7, and the outer peripheral surface 20 that reaches the end surface of the end 2a of the metal sheath tube 2. ing. The end surface 13c of the spacer material 13 is set so as to be substantially flush with the end surface of the metal sheath tube 2, whereby the excess space is almost eliminated.

By providing the spacer material 13 in this way, it is possible to eliminate the excess space in which the heat-resistant insulating material 8 is difficult to be compression-filled, prevent deterioration of the withstand voltage characteristics, and also because of the presence of the sleeve 6, the heat-resistant insulating material as a whole. The packing density of 8 can be uniformly increased, and the withstand voltage characteristics can be improved.

Similar to the conventional microheater, various forms can be adopted, such as providing a terminal portion (nut / lead wire extension) on the end side of the non-heating portion 11 opposite to the heat generating portion 10. The metal cladding tube 7 may be lengthened to serve as a routing wire for the non-heating portion. Further, although the single-core type is illustrated in this embodiment, it is of course possible to use a multi-core type in which a plurality of sets of heating wires and non-heating wires are present. In this case, the sleeve 6 may be provided at the joint portion between the heating wire and the non-heating wire of each set.

In the manufacturing procedure of the microheater 1 of the present embodiment, first, the heating wire 3 extends from the end of the metal sheath tube 2 of the heat generating portion 10 by a predetermined length, and a predetermined region extending to at least the tip of the extending portion 3a is formed. With the sleeve 6 attached to the outer peripheral surface 30, the end portion 6a of the sleeve 6 is joined to the end portion 5b of the non-heating wire 5 by welding or the like.

Next, the metal cladding tube 7 is made of metal via the bushing 9 and the spacer material 13 so as to cover at least a part of the joining side of the heating wire extending portion 3a, the sleeve 6, and the non-heating wire 5. It is connected to the end portion 2a of the sheath tube 2, and further, the gap inside the metal cladding tube 7 is filled with a heat-resistant insulating material 8 from the opening on the non-heating wire side thereof to seal the opening.

Then, the metal cladding tube 7 is pressure-reduced by die pulling or aging as in the conventional case. By this pressure reduction, the heat-resistant insulating material 8 inside is compressed and filled, and the sleeve 6 inside is brought into close contact with the outer peripheral surface 30 of the extending portion 3a of the heating wire 3 inside.

Although the embodiments of the present invention have been described above, the present invention is not limited to these examples, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

1 Microheater 2 Metal sheath tube 2a End 3 Heating wire 3a Extended part 4 Heat-resistant insulating material 5 Non-heating wire 5b End 6 Sleeve 6a End 6b End 7 Metal cladding tube 8 Heat-resistant insulating material 9 Bushing 9a End Part 10 Heat-generating part 10a End part 11 Non-heating part 12 Welded joint part 13 Spacer material 13c End face 20 Outer peripheral surface 30 Outer peripheral surface 71 Inner peripheral surface 101 Microheater 102 Stepped part s1 Surplus space

Claims (4)

A heat-generating portion is provided in which a heating wire is housed in a metal sheath tube and a heat-resistant insulating material is filled in a gap. Is a microheater that is connected in the axial direction.
A heating wire extends a predetermined length from the end of the metal sheath tube of the heating portion.
A metal sleeve is attached to the outer peripheral surface of a predetermined region reaching at least the tip of the extending portion.
The end of the sleeve opposite to the end facing the metal sheath tube is joined to the end of the non-heating wire.
The extending portion of the heating wire, the sleeve, and at least a part of the non-heating wire on the joined side are housed in a tubular metal cladding tube connected to the end of the metal sheath tube. At the same time, the gap in the metal cladding tube is filled with a heat-resistant insulating material.
As a result, the microheater is characterized in that the region where the sleeve and the non-heating wire of the metal cladding tube are located is configured as the non-heating portion. The first aspect of the present invention, wherein the non-heating wire is a metal wire or a metal rod, and the opposite end of the sleeve and the end of the non-heating wire are welded and joined in a coaxially abutted state. Micro heater. The microheater according to claim 1 or 2, wherein the metal cladding tube is pressurized and reduced in diameter together with the sleeve and the non-heating wire inside. The metal cladding tube is connected to the outer peripheral surface of the metal sheath tube via a bushing.
3. Or the microheater according to item 1.

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