Sheathed heater

Abstract

To provide technique enabling liquid to be efficiently heated.SOLUTION: A sheathed heater may comprises a tubular housing disposed in liquid flow, a heat-generating element housed in the housing, and a projected portion or recessed portion provided on a surface of the housing. The projected portion or recessed portion may be provided at a portion where the liquid flowing from the upstream side to the downstream side of the housing comes in contact with the surface of the housing and then leaves the surface of the housing.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] A sheathed heater is disclosed in Patent Document 1. The sheathed heater includes a tubular housing and a heating element housed in the housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-223375 A Summary of the Invention [Problem to be solved by the invention]

[0004] A sheathed heater, for example, is disposed in a liquid flow, and may heat the liquid in contact with the surface of the housing by heat from a heating element. In this case, in the sheathed heater, the liquid may stagnate in a portion immediately downstream of the housing in the direction of the liquid flow. In the portion where the liquid stagnates, the liquid does not flow sequentially downstream, so there is a problem in that the heat from the heating element cannot be efficiently transferred to the liquid. As a result, there is a problem in that the liquid cannot be efficiently heated. This specification provides a technology that can efficiently heat liquid. [Means for solving the problem]

[0005] In a first aspect of the present technology, a sheathed heater for heating a liquid may include a tubular housing disposed in a flow of the liquid, a heating element accommodated in the housing, and a protrusion or recess provided on a surface of the housing. The protrusion or recess may be provided in a portion where the liquid flowing from the upstream side to the downstream side of the housing comes into contact with the surface of the housing and then leaves the surface of the housing.

[0006] According to this configuration, a convex or concave portion is provided at the portion where the liquid flowing from the upstream side to the downstream side of the housing separates from the surface of the housing, and the convex or concave portion is the starting point for generating turbulence in the flow of the liquid on the downstream side of the housing. This causes the portion immediately downstream of the housing in the direction of the liquid flow to be agitated, and it is possible to prevent the liquid from accumulating in the portion immediately downstream of the housing. As a result, the liquid heated on the surface of the housing can be made to flow sequentially downstream, and the heat of the heating element can be efficiently transferred to the liquid. Therefore, the liquid can be efficiently heated.

[0007] In a second aspect, in the first aspect described above, the surface of the housing other than the portion in which the convex portion or the concave portion is provided may be configured in a curved shape without having any convex portion or concave portion.

[0008] With this configuration, the liquid can flow smoothly in the areas of the surface of the housing where there are no protrusions or recesses, and turbulence can be generated in the liquid in the areas where there are protrusions or recesses, allowing the heat from the heating element to be efficiently transferred to the liquid via the housing.

[0009] In a third aspect, in the first or second aspect, the housing may be configured in a spiral shape when viewed in a plan view. With this configuration, the liquid flowing in a radial direction of the spiral housing can be efficiently heated. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a side view of the sheath heater of the first embodiment. [Diagram 2] Cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 6 is a plan view of a sheathed heater according to a second embodiment. [Figure 4] FIG. 3 is a cross-sectional view of a modified sheath heater (corresponding to FIG. 2). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First Example) A sheathed heater 2 of a first embodiment will be described with reference to the drawings. As shown in Fig. 1, the sheathed heater 2 includes a heating unit 10 and a terminal unit 60. The sheathed heater 2 is a device that performs heating using the heating unit 10. The sheathed heater 2 heats, for example, a liquid flowing through a flow path 90 using the heating unit 10. The sheathed heater 2 is used, for example, in a state fixed to a pipe 92 that constitutes the liquid flow path 90.

[0012] The configuration of the heating unit 10 of the sheathed heater 2 will be described. The heating unit 10 is configured, for example, in a U-shape when viewed from the side. The heating unit 10 is inserted into a flow path 90 through which 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 disposed in the flow of the liquid flowing through the flow path 90, and heats the liquid flowing through the flow path 90.

[0013] The heating unit 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 configured. The first portion 51 and the second portion 52 each extend in a substantially straight line. The first portion 51 and the second portion 52 each extend in a direction intersecting the flow direction of the liquid flowing through the flow channel 90 (the longitudinal direction of the flow channel 90). For example, the first portion 51 and the second portion 52 each extend in a direction perpendicular to the flow direction of the liquid flowing through the flow channel 90. The second portion 52 is disposed downstream of the first portion 51 in the flow direction of the liquid flowing through the flow channel 90. The third portion 53 is disposed between the first portion 51 and the second portion 52. The third portion 53 is curved and connects the first portion 51 and the second portion 52.

[0014] As shown in FIG. 2, the heating unit 10 includes a heating element 12, a tubular housing 20 that houses the heating element 12, and a powdered insulating material 14 that fills the gap between the heating element 12 and the housing 20.

[0015] The heating element 12 is made of, for example, a spiral nichrome wire. The heating element 12 generates heat when electricity is applied. The insulating material 14 is made of, for example, magnesium oxide powder. The insulating material 14 insulates the heating element 12 from the housing 20. The principle by which the heating unit 10 of the sheathed heater 2 generates heat is already known, so a detailed explanation will be omitted.

[0016] The housing 20 covers the heating element 12 and the insulating material 14. The housing 20 is disposed in the flow of liquid flowing through 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 through the housing 20.

[0017] The housing 20 is configured, for example, in a circular tube shape in cross section. In a modified example, the housing 20 may be configured in an elliptical tube shape or an oval tube shape in cross section. The housing 20 has a plurality of protrusions 22 provided on its outer surface 20a. The plurality of protrusions 22 are provided all around the housing 20. The plurality of protrusions 22 are provided in a line at intervals in the circumferential direction of the housing 20. The plurality of protrusions 22 extend in parallel in the longitudinal direction of the housing 20 (not shown). In a modified example, the plurality of protrusions 22 may be provided in a dot pattern on the surface 20a of the housing 20.

[0018] Some of the protrusions 22 on the surface 20a of the housing 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 housing 20 comes into contact with the surface 20a of the housing 20 and then leaves the surface 20a of the housing 20. The specific portion P is also called a separation point. For example, the specific portion P is a portion between a portion where the surface 20a of the housing 20 faces the upstream side and a portion where the surface 20a of the housing 20 faces the downstream side in the flow direction of the liquid flowing through the flow path 90. The specific portion P is, for example, a portion within a range of ±10° on the upstream and downstream sides with respect to a virtual line V1 that passes through the center of the heating element 12 and extends in a direction perpendicular to the flow direction of the liquid (the longitudinal direction of the flow path 90) when the housing 20 is viewed in cross section.

[0019] Next, the configuration of the terminal portion 60 (see FIG. 1) will be described. The terminal portion 60 is electrically connected to a power source (not shown) that supplies power to the sheathed heater 2. The terminal portion 60 is disposed 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, for example, around the periphery of an opening 94 of the pipe 92.

[0020] The terminal unit 60 includes a positive terminal 60a and a negative terminal 60b. The positive terminal 60a of the terminal unit 60 is electrically connected to a positive terminal (not shown) of the heating element 12. The negative terminal 60b of the terminal unit 60 is electrically connected to a negative terminal (not shown) of the heating element 12. Electricity is supplied to the heating element 12 through the terminal unit 60. When the heating element 12 generates heat by energizing it, the heat is transferred to the liquid via the housing 20. The liquid in contact with the surface 20a of the housing 20 is heated by the heat of the heating element 12.

[0021] (effect) The sheathed heater 2 of the first embodiment has been described above. As is clear from the above description, in the above sheathed heater 2, a plurality of protrusions 22 are provided on the surface 20a of the housing 20. Some of the plurality of protrusions 22 are provided in a portion (specific portion P) where the liquid flowing from the upstream side to the downstream side of the housing 20 moves away from the surface 20a of the housing 20 after coming into contact with the surface 20a of the housing 20.

[0022] According to this configuration, turbulence occurs in the flow of the liquid downstream of the housing 20, starting from the protrusion 22 provided on the specific portion P. This agitates the portion B immediately downstream of the housing 20 in the direction of the liquid flow, making it possible to prevent the liquid from accumulating in the portion B immediately downstream of the housing 20. As a result, the liquid heated on the surface 20a of the housing 20 can be made to flow sequentially downstream, and the heat of the heating element 12 can be efficiently transferred to the liquid. Thus, the liquid can be efficiently heated.

[0023] Although the first embodiment has been described above, the aspect of the sheathed heater 2 is not limited to the above embodiment. In the following description, detailed description of the same configuration as in the above description may be omitted.

[0024] (Second Example) In the second embodiment, as shown in Fig. 3, the heating section 10 of the sheathed heater 2 is configured in a spiral shape in a plan view. The heating section 10 of the sheathed heater 2 is housed inside the outer housing 4. The outer housing 4 includes a housing section 40 that houses the spiral heating section 10.

[0025] The spiral heating part 10 has an inner end 17 and an outer end 18 in the spiral direction. The inner end 17 and the outer end 18 each have an electrode terminal (not shown). Electric power is supplied to the heating element 12 of the heating part 10 through the electrode terminal of the inner end 17 and the electrode terminal of the outer end 18. Each of the multiple windings of the spiral heating part 10 makes one revolution in the spiral direction of the heating part 10.

[0026] In the second embodiment, liquid is introduced into the accommodation section 40 of the outer housing 4. The liquid introduced into the accommodation section 40 is introduced toward the center section 16 of the spiral heating section 10. The liquid introduced into the center section 16 of the heating section 10 flows radially from the center section 16 of the heating section 10 to the outside in the radial direction of the heating section 10. This liquid is heated by the heating section 10 while flowing in the radial direction of the heating section 10.

[0027] In a modified example, the liquid may be introduced toward the periphery of the spiral heating unit 10. The liquid introduced to the periphery of the heating unit 10 flows radially from the periphery of the heating unit 10 toward the center 16 of the heating unit 10 inward in the radial direction of the heating unit 10. This liquid is heated by the heating unit 10 while flowing in the radial direction of the heating unit 10.

[0028] A cross-sectional view of the second embodiment taken along line II-II of Fig. 3 is shown in Fig. 2. As shown in Fig. 2, the heating section 10 of the sheathed heater 2 of the second embodiment includes a heating element 12, a housing 20, and an insulating material 14, similar to the first embodiment. The cross-sectional configuration of the heating section 10 of the second embodiment is similar to that of the first embodiment, and therefore a detailed description thereof will be omitted.

[0029] According to the above configuration, since the housing 20 is configured in a spiral shape when viewed in a plan view, the liquid flowing in the radial direction of the housing 20 can be efficiently heated.

[0030] (Modification) (1) In the above embodiment, the multiple protrusions 22 are provided around the entire circumference of the surface 20a of the housing 20, but the present invention is not limited to this configuration. In a modified example, as shown in Fig. 4, the multiple protrusions 22 may be provided on a specific portion P of the surface 20a of the housing 20, and no protrusions may be provided on a portion S of the surface 20a of the housing 20 other than the specific portion P.

[0031] In the modified example, the housing 20 includes a first convex group 200 and a second convex group 202. The first convex group 200 and the second convex group 202 are provided on the surface 20a of the housing 20. The first convex group 200 and the second convex group 202 each include a plurality of convex portions 22. The first convex group 200 and the second convex group 202 are provided at positions point-symmetrical with respect to the heating element 12. The first convex group 200 and the second convex group 202 are each provided at a specific portion P. The first convex group 200 and the second convex group 202 are each provided within a range of ±10° on the upstream side and downstream side of a virtual line V1 that passes through the center of the heating element 12 and extends in a direction perpendicular to the liquid flow direction (the longitudinal direction of the flow path 90) when the housing 20 is viewed in cross section. The first convex portion group 200 and the second convex portion group 202 are each 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.

[0032] In the modified example, a portion S of the surface 20a of the housing 20 other than the specific portion P (i.e., a portion where the first convex portion group 200 and the second convex portion group 202 are not provided) is configured to have a curved surface. The curvature of this portion S is smaller than the curvature of each convex portion 22.

[0033] According to the above configuration, the liquid can flow smoothly in the portion of the surface 20a of the housing 20 where no protrusions are provided, and turbulent flow can be generated in the liquid in the portion where the protrusions 22 are provided. This allows the heat of the heating element 12 to be efficiently transferred to the liquid via the housing 20.

[0034] (2) In the above embodiment, a plurality of protrusions 22 are provided on the specific portion P of the surface 20a of the housing 20, but the present invention is not limited to this configuration. In a modified example, a plurality of recesses (not shown) may be provided on the specific portion P of the surface 20a of the housing 20 instead of the plurality of protrusions 22. With this configuration, turbulence can be generated in the liquid starting from the recesses.

[0035] (3) There is no particular limitation on the number of protrusions 22 or recesses in the specific portion P of the surface 20a of the housing 20. It is sufficient that one or more protrusions 22 or recesses are provided in the specific portion P of the surface 20a of the housing 20.

[0036] Although specific examples of the present invention have been described above in detail, 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. In addition, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful. [Explanation of symbols]

[0037] 2: sheath heater, 10: heating portion, 12: heating element, 14: insulating material, 16: center portion, 20: housing, 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

Claims

1. A sheath heater for heating a liquid, a tubular housing disposed within the liquid flow; A heating element housed in the housing; and A protrusion or a recess is provided on a surface of the housing, A sheath heater, wherein the convex portion or the concave portion is provided in a portion where liquid flowing from the upstream side to the downstream side of the housing comes into contact with the surface of the housing and then leaves the surface of the housing.

2. The sheath heater according to claim 1, A sheath heater, wherein a portion of the surface of the housing other than the portion where the protrusion or recess is provided is configured to be curved without having any protrusion or recess.

3. The sheath heater according to claim 1 or 2, The housing of the sheath heater is configured in a spiral shape when viewed in a plan view.

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