Heater

Abstract

To provide a technique capable of maintaining a withstand voltage even when a metal tube is deformed.SOLUTION: A heater includes a metal tube, a wound resistance heating portion disposed inside the metal tube, a terminal portion disposed between an inside and an outside of the metal tube and having one end connected to the resistance heating portion inside the metal tube and the other end led out from an opening portion of the metal tube to the outside, and an insulating material filled around a resistance heating portion and the terminal portion inside the metal tube. The terminal portion may include a winding-shaped first portion connected to the resistance heating portion inside the metal tube, and a linear second portion having a diameter larger than a wire diameter of a first portion, one end portion of which is connected to the first portion inside the metal tube, and the other end portion of which is led out to the outside from the opening portion of the metal tube.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a heater. [Background technology]

[0002] Patent Document 1 discloses a heater. The heater in Patent Document 1 includes a metal tube, a wound resistance heating part disposed inside the metal tube, a terminal part disposed inside and outside the metal tube, one end of which is connected to the resistance heating part inside the metal tube and the other end of which is drawn out from an opening of the metal tube to the outside, and an insulating material filled inside the metal tube around the resistance heating part and the terminal part. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-69256 Summary of the Invention [Problem to be solved by the invention]

[0004] The heater in Patent Document 1 is arranged inside the main body in a spirally wound state. In such a configuration, the metal tube of the heater may be deformed by bending. In this case, if the metal tube is deformed in the area where the terminal is arranged inside the metal tube, a gap may occur between the terminal and the surrounding insulating material, which may reduce the withstand voltage of that area. Therefore, this specification provides a technology that can maintain the withstand voltage even if the metal tube is deformed. [Means for solving the problem]

[0005] In a first aspect of the present technology, a heater includes a metal tube, a wound resistance heating portion disposed inside the metal tube, a terminal portion disposed across the inside and outside of the metal tube, one end connected to the resistance heating portion inside the metal tube and the other end drawn out to the outside through an opening of the metal tube, and an insulating material filling the inside of the metal tube around the resistance heating portion and the terminal portion. The terminal portion may include a wound first portion connected to the resistance heating portion inside the metal tube, and a linear second portion having a wire diameter larger than that of the first portion, one end connected to the first portion inside the metal tube and the other end drawn out to the outside through the opening of the metal tube.

[0006] In a heater in which a resistance heating element is disposed inside a metal tube, the metal tube may be bent, for example, to position the portion where the resistance heating element is disposed appropriately relative to the object to be heated. In this case, the metal tube may be deformed at the portion where the terminal portion is disposed inside the metal tube. In this case, according to the above configuration, since the terminal portion connected to the resistance heating element includes a wound first portion, the wound first portion follows the deformation of the metal tube, thereby preventing gaps from occurring between the terminal portion and the insulating material surrounding it. This allows the withstand voltage to be maintained even if the metal tube is deformed.

[0007] In a second aspect, the metal pipe in the first aspect may include a straight portion extending linearly in the axial direction and a curved portion extending curvedly in the axial direction. The first portion of the terminal may be disposed inside the metal pipe across the straight portion and the curved portion of the metal pipe. The second portion of the terminal may have one end connected to the first portion inside the straight portion of the metal pipe and the other end drawn out to the outside from the opening provided in the straight portion of the metal pipe.

[0008] With this configuration, the second portion of the terminal is disposed inside the straight portion of the metal pipe, and the first portion of the terminal is disposed inside the curved portion of the metal pipe, so that the first portion of the terminal follows the shape of the curved portion of the metal pipe, thereby preventing gaps from occurring between the terminal and the insulating material around it, thereby maintaining the withstand voltage.

[0009] In a third aspect, in the first or second aspect, the terminal portion may be connected to the resistance heating portion by welding.

[0010] The welded portion is easily weakened and prone to poor electrical conductivity, but with the above configuration, the wound first portion follows the deformation of the metal pipe, thereby maintaining electrical conductivity in the welded portion. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. [Figure 2] 1. FIG. 2 is a cross-sectional view of part II of FIG. [Figure 3] Cross-sectional view of III-III in Figure 2. [Figure 4] IV-IV cross section of Figure 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] A heater according to an embodiment will be described with reference to the drawings. As shown in Figures 1 and 2, the heater 2 according to the embodiment includes a metal tube 10, a resistance heating part 20 disposed inside the metal tube 10, and terminal parts 30 disposed both inside and outside the metal tube 10. The heater 2 is wound around a shaft member 90, for example.

[0013] The metal tube 10 has thermal conductivity and electrical conductivity. The metal tube 10 is made of, for example, stainless steel (SUS). The material of the metal tube 10 is not particularly limited, but a material having lower electrical resistance than the material of the resistance heating part 20 is used. As shown in FIG. 3, the metal tube 10 is configured to have a circular cross-sectional shape. The cross-sectional shape of the metal tube 10 is not particularly limited, and may be, for example, an elliptical or polygonal shape.

[0014] An opening 18 is provided at one axial end of the metal pipe 10. A similar opening 18 may be provided at the other axial end of the metal pipe 10 (not shown). In a modified example, the other axial end of the metal pipe 10 may not be provided with an opening 18, and the other axial end of the metal pipe 10 may be closed.

[0015] The metal tube 10 has a helical portion 12, a curved portion 14, and a straight portion 16. The helical portion 12, the curved portion 14, and the straight portion 16 are aligned in the axial direction of the metal tube 10. The helical portion 12 extends helically along the axial direction of the metal tube 10.

[0016] The curved portion 14 extends in a curved shape along the axial direction of the metal pipe 10. The curved portion 14 is curved or bent. The curved portion 14 is located between the spiral portion 12 and the straight portion 16. As shown in FIG. 4, the curved portion 14 is configured to have, for example, an elliptical shape in cross section. The cross-sectional shape of the curved portion 14 changes from a circular shape to an elliptical shape when the metal pipe 10 is bent.

[0017] The straight portion 16 extends linearly along the axial direction of the metal pipe 10. The straight portion 16 is located closer to the end of the metal pipe 10 (toward the opening 18) than the curved portion 14. The opening 18 is provided at the end of the straight portion 16.

[0018] The resistance heating part 20 has thermal conductivity and electrical conductivity. The resistance heating part 20 generates heat when electricity is applied. The resistance heating part 20 is made of, for example, nichrome wire. The material of the resistance heating part 20 is not particularly limited, but a material having a higher electrical resistance than the materials of the metal tube 10 and the terminal part 30 is used.

[0019] The resistance heating part 20 is configured in a wound shape and extends in the axial direction of the metal tube 10 in a wound state. All or a part of the resistance heating part 20 is disposed inside the spiral part 12 of the metal tube 10. The end of the resistance heating part 20 may be disposed inside the spiral part 12 of the metal tube 10, or may be disposed inside the curved part 14 of the metal tube 10.

[0020] The terminal portion 30 has thermal conductivity and electrical conductivity. The terminal portion 30 is made of, for example, stainless steel (SUS). The material of the terminal portion 30 is not particularly limited, but a material having lower electrical resistance than the material of the resistance heating portion 20 is used. The electrical resistance per unit length of the terminal portion 30 is lower than the electrical resistance per unit length of the resistance heating portion 20.

[0021] The terminal portion 30 is connected to the resistance heating portion 20. One end of the terminal portion 30 is connected to an end of the resistance heating portion 20 inside the metal tube 10. The terminal portion 30 and the resistance heating portion 20 are connected by, for example, welding. The terminal portion 30 extends in the axial direction of the metal tube 10. The other end of the terminal portion 30 is drawn out from the opening 18 of the metal tube 10 to the outside. The other end of the terminal portion 30 is electrically connected to an external power source (not shown). Power is supplied to the resistance heating portion 20 from the external power source via the terminal portion 30. This causes the resistance heating portion 20 to generate heat.

[0022] The terminal portion 30 includes a first portion 32 and a second portion 34. The first portion 32 is configured in a wound shape and is disposed inside the metal tube 10. The first portion 32 extends in the axial direction of the metal tube 10 in a wound state. All or part of the first portion 32 is disposed inside the curved portion 14 of the metal tube 10. One end of the first portion 32 is connected to an end of the resistance heating portion 20 inside the metal tube 10. The first portion 32 and the resistance heating portion 20 are connected by welding. The connection portion between the first portion 32 and the resistance heating portion 20 may be disposed inside the curved portion 14 of the metal tube 10 or inside the spiral portion 12 of the metal tube 10.

[0023] The other end of the first portion 32 is connected to an end of the second portion 34 inside the metal tube 10. The first portion 32 is located between the resistance heating portion 20 and the second portion 34. The first portion 32 and the second portion 34 are connected by welding. The connecting portion between the first portion 32 and the second portion 34 is located inside the straight portion 16 of the metal tube 10.

[0024] The second portion 34 is disposed both inside and outside the metal pipe 10. One end of the second portion 34 is connected to the other end of the first portion 32 inside the straight portion 16 of the metal pipe 10. The second portion 34 is configured in a straight line and extends in the axial direction of the metal pipe 10. The diameter of the second portion 34 is larger than the wire diameter of the wound first portion 32. The other end of the second portion 34 is disposed outside the metal pipe 10. The other end of the second portion 34 is drawn out from the opening 18 of the metal pipe 10 to the outside. The other end of the second portion 34 is electrically connected to an external power source (not shown).

[0025] The heater 2 of the embodiment further includes an insulating material 40 filled around the resistance heating portion 20 and the terminal portion 30 inside the metal tube 10, and a sealing member 50 that seals the opening 18 of the metal tube 10. The heater 2 also includes an insulating porcelain 60 attached to the terminal portion 30 outside the metal tube 10.

[0026] The insulating material 40 is, for example, powdered magnesium oxide (MgO). The insulating material 40 electrically insulates the resistance heating portion 20 and the terminal portion 30 from the metal tube 10. The insulating material 40 is filled between the inner surface of the metal tube 10 and the outer surface of the resistance heating portion 20. The insulating material 40 is also filled between the inner surface of the metal tube 10 and the outer surface of the terminal portion 30.

[0027] The sealing member 50 is made of, for example, a resin (e.g., silicone rubber). The sealing member 50 is filled between the inner surface of the metal pipe 10 and the outer surface of the second portion 34 of the terminal 30 at the opening 18 of the metal pipe 10. Note that, in order to improve the sealing performance of the opening 18, a predetermined sealing treatment may be further applied to the sealing member 50.

[0028] (effect) The heater 2 of the embodiment has been described above. As is clear from the above description, in the heater 2, the terminal portion 30 includes a wound first portion 32 connected to the resistance heating portion 20 inside the metal tube 10, and a linear second portion 34 having a wire diameter larger than that of the first portion 32, with one end connected to the first portion 32 inside the metal tube 10 and the other end drawn out from the opening 18 of the metal tube 10 to the outside.

[0029] According to this configuration, the terminal portion 30 connected to the resistance heating portion 20 includes the wound first portion 32, and the wound first portion 32 follows the deformation of the metal tube 10, thereby preventing a gap from being generated between the terminal portion 30 and the surrounding insulating material 40. This makes it possible to maintain the withstand voltage even if the metal tube 10 is deformed. For example, as shown in FIG. 4, the withstand voltage can be maintained even if the metal tube 10 is deformed into an elliptical shape.

[0030] The first portion 32 of the terminal portion 30 is disposed inside the metal pipe 10 across the straight portion 16 and the curved portion 14 of the metal pipe 10. One end of the second portion 34 of the terminal portion 30 is connected to the first portion 32 inside the straight portion 16 of the metal pipe 10, and the other end is drawn out from an opening 18 provided in the straight portion 16 of the metal pipe 10 to the outside.

[0031] With this configuration, the second portion 34 of the terminal portion 30 is disposed inside the straight portion 16 of the metal pipe 10, and the first portion 32 of the terminal portion 30 is disposed inside the curved portion 14 of the metal pipe 10, so that the first portion 32 of the terminal portion 30 follows the shape of the curved portion 14 of the metal pipe 10, thereby preventing gaps from occurring between the terminal portion 30 and the surrounding insulating material 40. This makes it possible to maintain the withstand voltage.

[0032] The terminal portion 30 is connected to the resistance heating portion 20 by welding. Welded portions tend to be brittle and prone to electrical conductivity failure, but with the above configuration, the wound first portion 32 follows the deformation of the metal pipe 10, making it possible to maintain electrical conductivity in the welded portion.

[0033] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0034] 2: heater, 10: metal tube, 12: spiral portion, 14: curved portion, 16: straight portion, 18: opening, 20: resistance heating portion, 30: terminal portion, 32: first portion, 34: second portion, 40: insulating material, 50: sealing member, 60: insulator, 90: shaft core member

Claims

1. A metal tube, a wound resistance heating portion disposed inside the metal tube; a terminal portion disposed inside and outside the metal tube, one end of which is connected to the resistance heating portion inside the metal tube and the other end of which is drawn out from an opening of the metal tube to the outside; an insulating material filled around the resistance heating portion and the terminal portion inside the metal tube, the terminal portion comprises a first wound portion connected to the resistance heating portion inside the metal tube, and a second straight portion having a wire diameter larger than that of the first portion, one end of the second portion being connected to the first portion inside the metal tube and the other end being pulled out to the outside through the opening of the metal tube.

2. 2. The heater of claim 1, the metal tube includes a linear portion extending linearly in the axial direction and a curved portion extending curvedly in the axial direction, the first portion of the terminal portion is disposed inside the metal tube across the straight portion and the curved portion of the metal tube, a heater, wherein one end of the second portion of the terminal portion is connected to the first portion inside the straight portion of the metal tube, and the other end is drawn out to the outside from the opening provided in the straight portion of the metal tube.

3. 3. The heater according to claim 1 or 2, The terminal portion is connected to the resistance heating portion by welding.

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