Sheath heater

Abstract

The invention relates to a sheathed heater. Provided is a technique capable of efficiently heating a liquid. The sheath heater may also include a tubular housing disposed in the flow of the liquid, a heating element housed in the housing, and a convex portion or a concave portion provided on the surface of the housing. The convex portion or the concave portion may be provided in a portion where the liquid flowing from the upstream side to the downstream side of the housing is separated from the surface of the housing after coming into contact with the surface of the housing.

Description

Technical Field

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

[0002] Patent Document 1 discloses a sheath heater. The sheath heater includes a tubular casing and a heating element accommodated in the casing.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-223375 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] For example, the sheath heater is sometimes arranged in the liquid flow, and the liquid in contact with the surface of the shell is heated by the heat of the heating element. At this time, in the sheath heater, the liquid sometimes stays in the part of the downstream side of the shell in the flow direction of the liquid. In the part where the liquid stays, the liquid cannot flow to the downstream side in sequence, so there is a problem that the heat of the heating element cannot be efficiently transferred to the liquid. As a result, there is a problem that the liquid cannot be efficiently heated. This specification provides a technology that can efficiently heat the liquid.

[0008] Solutions for solving problems

[0009] In the first technical solution of the present technology, it may be a sheath heater that heats liquid, wherein the sheath heater comprises: a tubular shell that is arranged in the liquid flow; a heating element that is accommodated in the shell; and a convex portion or a concave portion that is provided on the surface of the shell. It may also be that the convex portion or the concave portion is provided at a portion where the liquid flowing from the upstream side to the downstream side of the shell leaves the surface of the shell after contacting the surface of the shell.

[0010] According to this structure, since the convex part or the concave part is provided at the part where the liquid flowing from the upstream side to the downstream side of the shell leaves the surface of the shell, turbulence is generated in the liquid flow on the downstream side of the shell starting from the convex part or the concave part. As a result, the part of the liquid flowing in the direction of the liquid close to the downstream side of the shell is stirred, so that the liquid can be suppressed from being retained in the part close to the downstream side of the shell. As a result, the liquid heated by the surface of the shell can flow to the downstream side in sequence, and the heat of the heating element can be efficiently transferred to the liquid. Therefore, the liquid can be efficiently heated.

[0011] In a second technical solution, according to the first technical solution, a portion of the surface of the housing other than a portion where the convex portion or the concave portion is provided is not provided with a convex portion or a concave portion, but is configured in a curved surface shape.

[0012] According to this structure, the liquid can flow smoothly in the portion of the shell surface where no convex or concave portion is provided, and the liquid can be turbulent in the portion where the convex or concave portion is provided, thereby efficiently transferring the heat of the heating element to the liquid via the shell.

[0013] In a third aspect, according to the first or second aspect, the housing may be configured to be spiral-shaped in a plan view. According to this configuration, the liquid flowing in the radial direction of the spiral housing can be efficiently heated. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a side view of the sheath heater of the first embodiment.

[0015] Figure 2 yes Figure 1 II-II sectional view.

[0016] Figure 3 It is a top view of the sheath heater according to the second embodiment.

[0017] Figure 4 is a cross-sectional view of a sheath heater of a modified example (equivalent to Figure 2 ).

[0018] Description of Reference Numerals

[0019] 2. Sheath heater; 10. Heating portion; 12. Heater; 14. Insulating material; 16. Center portion; 20. Shell; 20a. Surface; 22. Protrusion; 60. Terminal portion; 90. Flow path; 92. Piping; 94. Opening; 200. First protrusion group; 202. Second protrusion group; P. Specific portion. DETAILED DESCRIPTION

[0020] (First embodiment)

[0021] The sheath heater 2 of the first embodiment will be described with reference to the accompanying drawings. Figure 1 As shown, the sheath heater 2 includes a heating portion 10 and a terminal portion 60. The sheath heater 2 is a device that performs heating by the heating portion 10. The sheath heater 2 heats, for example, liquid flowing in a flow path 90 by the heating portion 10. The sheath heater 2 is used in a state of being fixed to a pipe 92 constituting the flow path 90 of the liquid, for example.

[0022] The structure of the heating unit 10 of the sheath heater 2 is described. The heating unit 10 is configured in a U-shape, for example, when viewed from the side. The heating unit 10 is inserted into the flow path 90 through which the liquid flows. The heating unit 10 is inserted into the flow path 90, for example, from an opening 94 provided in a pipe 92. The heating unit 10 is arranged in the liquid flow of the liquid flowing in the flow path 90, and heats the liquid flowing in the flow path 90.

[0023] The heating section 10 includes a first portion 51, a second portion 52, and a third portion 53. The first portion 51, the second portion 52, and the third portion 53 are integrally formed. The first portion 51 and the second portion 52 extend in a substantially straight line, respectively. The first portion 51 and the second portion 52 extend in a direction intersecting the flow direction of the liquid flowing in the flow path 90 (the length direction of the flow path 90), respectively. For example, the first portion 51 and the second portion 52 extend in a direction orthogonal to the flow direction of the liquid flowing in the flow path 90, respectively. In the flow direction of the liquid flowing in the flow path 90, the second portion 52 is disposed at a position downstream of the first portion 51. The third portion 53 is disposed between the first portion 51 and the second portion 52. The third portion 53 is bent to connect the first portion 51 and the second portion 52.

[0024] like Figure 2 As shown, the heating unit 10 includes a heating element 12 , a tubular housing 20 that accommodates the heating element 12 , and a powdery insulating material 14 that fills a gap between the heating element 12 and the housing 20 .

[0025] The heating element 12 is composed of, for example, a spiral nickel-chromium alloy wire. The heating element 12 generates heat by passing electricity. The insulating material 14 is composed of, for example, magnesium oxide powder. The insulating material 14 insulates the heating element 12 from the housing 20. In addition, since the principle of heat generation by the heating portion 10 of the sheath heater 2 is well known, a detailed description is omitted.

[0026] The housing 20 covers the heating element 12 and the insulating material 14. The housing 20 is disposed in the flow of the liquid flowing in the flow path 90. The liquid in contact with the surface 20a of the housing 20 is heated by the heat of the heating element 12. The heat of the heating element 12 is transferred to the liquid via the housing 20.

[0027] The shell 20 is configured as a circular tube when viewed in section. In a modified example, the shell 20 may also be configured as an elliptical tube or an oblong tube when viewed in section. The shell 20 has a plurality of protrusions 22 provided on a surface 20a of its outer side. A plurality of protrusions 22 are provided on the entire circumference of the shell 20. The plurality of protrusions 22 are arranged in an interval in the circumferential direction of the shell 20. The plurality of protrusions 22 extend in parallel in the longitudinal direction of the shell 20 (not shown). In a modified example, the plurality of protrusions 22 may also be provided in a dotted manner on the surface 20a of the shell 20.

[0028] Some of the protrusions 22 provided on the surface 20a of the shell 20 are provided in a specific portion P. The specific portion P is a portion where the liquid flowing from the upstream side to the downstream side of the shell 20 leaves the surface 20a of the shell 20 after contacting the surface 20a of the shell 20. The specific portion P is sometimes also referred to as a peeling point. The specific portion P is, for example, a portion between a portion of the surface 20a of the shell 20 facing the upstream side and a portion of the surface 20a of the shell 20 facing the downstream side in the flow direction of the liquid flowing in the flow path 90. The specific portion P is, for example, a portion within a range of ±10° deflected toward the upstream and downstream sides with an imaginary line V1 as the center, the imaginary line V1 passing through the center of the heating element 12 when the shell 20 is cross-sectioned, and extending in a direction orthogonal to the flow direction of the liquid (the length direction of the flow path 90).

[0029] Next, the terminal portion 60 (see Figure 1 ) is described below. The terminal portion 60 is electrically connected to a power source (not shown) that supplies power to the sheath heater 2. The terminal portion 60 is arranged between the power source and the heating portion 10. The terminal portion 60 supplies power from the power source to the heating portion 10. The terminal portion 60 is fixed around the opening portion 94 of the piping 92, for example.

[0030] The terminal portion 60 includes a positive terminal 60a and a negative terminal 60b. The positive terminal 60a of the terminal portion 60 is electrically connected to the positive terminal (not shown) of the heating element 12. The negative terminal 60b of the terminal portion 60 is electrically connected to the negative terminal (not shown) of the heating element 12. Electricity is supplied to the heating element 12 via the terminal portion 60. When the heating element 12 generates heat by being energized, the heat is transferred to the liquid via the shell 20. The liquid in contact with the surface 20a of the shell 20 is heated by the heat of the heating element 12.

[0031] (Effect)

[0032] The sheath heater 2 of the first embodiment has been described above. As is clear from the above description, in the sheath heater 2, a plurality of convex portions 22 are provided on the surface 20a of the shell 20. Some of the convex portions 22 are provided in the portion (specific portion P) where the liquid flowing from the upstream side to the downstream side of the shell 20 leaves the surface 20a of the shell 20 after contacting the surface 20a of the shell 20.

[0033] According to this structure, turbulence is generated in the liquid flow on the downstream side of the housing 20, starting from the convex portion 22 provided at the specific portion P. As a result, the portion B on the downstream side of the housing 20 in the flow direction of the liquid is stirred, so that the liquid can be suppressed from stagnating in the portion B on the downstream side of the housing 20. As a result, the liquid heated by the surface 20a of the housing 20 can flow to the downstream side in sequence, and the heat of the heating element 12 can be efficiently transferred to the liquid. Therefore, the liquid can be efficiently heated.

[0034] The first embodiment has been described above, but the form of the sheath heater 2 is not limited to the above embodiment. In the following description, detailed descriptions of the same configurations as those described above may be omitted.

[0035] (Second embodiment)

[0036] In the second embodiment, Figure 3 As shown, the heating portion 10 of the sheath heater 2 is formed in a spiral shape in a plan view. The heating portion 10 of the sheath heater 2 is accommodated inside the outer case 4. The outer case 4 includes an accommodation portion 40 for accommodating the spiral heating portion 10.

[0037] The spiral heating portion 10 includes an inner end 17 and an outer end 18 in the spiral direction. The inner end 17 and the outer end 18 each include an electrode terminal (not shown). Power is supplied to the heating element 12 of the heating portion 10 via the electrode terminal of the inner end 17 and the electrode terminal of the outer end 18. The plurality of surrounding portions of the spiral heating portion 10 each surround the heating portion 10 in the spiral direction.

[0038] In the second embodiment, liquid is introduced into the container 40 of the outer housing 4. The liquid introduced into the container 40 is introduced toward the center 16 of the vortex-shaped heating portion 10. The liquid introduced into the center 16 of the heating portion 10 flows radially from the center 16 of the heating portion 10 toward the outside in the radial direction of the heating portion 10. The liquid is heated by the heating portion 10 while flowing in the radial direction of the heating portion 10.

[0039] In addition, in a modified example, the liquid may be introduced toward the periphery of the vortex-shaped heating portion 10. The liquid introduced into the periphery of the heating portion 10 flows radially from the periphery of the heating portion 10 toward the central portion 16 of the heating portion 10 toward the radial inner side of the heating portion 10. The liquid is heated by the heating portion 10 while flowing in the radial direction of the heating portion 10.

[0040] exist Figure 2 The second embodiment is shown in Figure 3 II-II section view. Figure 2As shown, the heating portion 10 of the sheath heater 2 of the second embodiment includes a heating element 12, a housing 20, and an insulating material 14, similarly to the first embodiment described above. Since the cross-sectional structure of the heating portion 10 of the second embodiment is similar to that of the first embodiment described above, detailed description thereof will be omitted.

[0041] According to the above configuration, since the casing 20 is formed in a spiral shape in a plan view, the liquid flowing in the radial direction of the casing 20 can be efficiently heated.

[0042] (Variation Example)

[0043] (1) In the above-mentioned embodiment, a plurality of protrusions 22 are provided on the entire circumference of the surface 20a of the housing 20, but the present invention is not limited to this structure. Figure 4 As shown, the following structure may be adopted: a plurality of protrusions 22 are provided in a specific portion P of the surface 20 a of the housing 20 , and no protrusions are provided in a portion S other than the specific portion P of the surface 20 a of the housing 20 .

[0044] In a modified example, the shell 20 includes a first protrusion group 200 and a second protrusion group 202. The first protrusion group 200 and the second protrusion group 202 are provided on the surface 20a of the shell 20. The first protrusion group 200 and the second protrusion group 202 each include a plurality of protrusions 22. The first protrusion group 200 and the second protrusion group 202 are provided at point-symmetrical positions with the heating element 12 as the center. The first protrusion group 200 and the second protrusion group 202 are provided at a specific portion P, respectively. The first protrusion group 200 and the second protrusion group 202 are provided within a range of ±10° deflected toward the upstream and downstream sides with an imaginary line V1 as the center, respectively, and the imaginary line V1 passes through the center of the heating element 12 when the shell 20 is viewed in section, and extends in a direction orthogonal to the flow direction of the liquid (the length direction of the flow path 90). The first convex portion group 200 and the second convex portion group 202 are respectively provided so as to straddle the imaginary line V1. In other modified examples, the first convex portion group 200 or the second convex portion group 202 may be omitted.

[0045] In the modified example, a portion S other than the specific portion P of the surface 20 a of the housing 20 (ie, a portion where the first convex portion group 200 and the second convex portion group 202 are not provided) is curved. The curvature of the portion S is smaller than that of each convex portion 22 .

[0046] According to the above structure, the liquid can flow smoothly in the portion without the protrusions on the surface 20a of the housing 20, and can generate turbulence in the portion with the protrusions 22. Thus, the heat of the heating element 12 can be efficiently transferred to the liquid via the housing 20.

[0047] (2) In the above-mentioned embodiment, a plurality of convex portions 22 are provided on a specific portion P of the surface 20a of the housing 20, but the present invention is not limited to this structure. In a modified example, a plurality of concave portions (not shown) may be provided on a specific portion P of the surface 20a of the housing 20 instead of the plurality of convex portions 22. According to this structure, turbulence can be generated in the liquid starting from the concave portions.

[0048] (3) The number of the convex portions 22 or concave portions in the specific portion P of the surface 20 a of the housing 20 is not particularly limited. It is sufficient that one or more convex portions 22 or concave portions are provided in the specific portion P of the surface 20 a of the housing 20 .

[0049] The specific examples of the present invention are described in detail above, but these are only examples and are not intended to limit the claims. The technology described in the claims includes technologies obtained by various deformations and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings are technically useful alone or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the technology illustrated in this specification or the drawings can achieve multiple purposes at the same time, and achieving one of the purposes itself has technical usefulness.

Claims

1. A sheath heater for heating a liquid, wherein: The sheath heater has: a tubular housing disposed in the flow of the liquid; a heating element contained in the housing; and a convex portion or a concave portion, which is provided on the surface of the housing, The convex portion or the concave portion is provided at a portion where the liquid flowing from the upstream side to the downstream side of the housing moves away from the surface of the housing after coming into contact with the surface of the housing.

2. The sheath heater according to claim 1, wherein: The surface of the housing is not provided with convex portions or concave portions except for the portion provided with the convex portions or the concave portions, and is configured in a curved surface shape.

3. The sheath heater according to claim 1 or 2, wherein: The housing is configured to have a spiral shape when viewed from above.

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