Jacket heater, method for manufacturing a jacket heater, and heat insulation structure

Abstract

A jacket heater (10) includes: a first heat insulation layer (11); a reflection layer (13) that is disposed outward of the first heat insulation layer (11); a second heat insulation layer (12) that is disposed outward of the reflection layer (13); and a heater wire (14) that is disposed inward of the first heat insulation layer (11). Thus, piping can be sufficiently heated while suppressing power consumption.

Description

Technical Field

[0001] The present invention relates to a jacket heater for covering piping, a method for manufacturing a jacket heater, and a heat insulation structure.

Background Art

[0002] In order to prevent condensation and precipitation of gas inside the piping, the piping may be covered with a jacket heater. For example, various gases are used in film formation processes and etching processes in the manufacture of semiconductor devices. Jacket heaters are sometimes used to prevent these gases from condensing and precipitating inside the piping. Patent Document 1 discloses an example of such a jacket heater.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Reducing power consumption in manufacturing equipment is important for manufacturing costs, environmental impact, and other factors. Therefore, reduction of power consumption is also required for jacket heaters. If the thickness of the heat insulation layer of the jacket heater is increased, power consumption can be suppressed. However, when the thickness of the heat insulation layer increases, a large space around the piping is required for installing the jacket heater. Accordingly, increasing the thickness of the heat insulation layer to reduce power consumption may not be desirable in some cases.

Means for Solving the Problem

[0005] The jacket heater proposed in this disclosure is a jacket heater for mounting on the outer circumference of a pipe, and comprises a first insulation layer, a reflective layer disposed outside the first insulation layer, a second insulation layer disposed outside the reflective layer, and a heater wire disposed inside the first insulation layer. Because this jacket heater has a reflective layer, the power consumption of the jacket heater is reduced and the pipe is sufficiently heated. In addition, because there is a second insulation layer outside the reflective layer, the outer surface of the jacket heater can be cooled to an appropriate temperature. As a result, workability around the jacket heater can be improved.

[0006] The method for manufacturing a jacket heater proposed in this disclosure includes the steps of sewing together a first insulating layer covering a heater wire, a reflective layer covering the outside of the first insulating layer, and a second insulating layer covering the outside of the reflective layer, and sewing the heater wire to the first insulating layer. According to the jacket heater manufactured by this method, the power consumption of the jacket heater is reduced and the piping is sufficiently heated. In addition, because there is a second insulating layer outside the reflective layer, the outer surface of the jacket heater can be cooled to an appropriate temperature. As a result, workability around the jacket heater can be improved.

[0007] The thermal insulation structure proposed in this disclosure is a thermal insulation structure for attachment to the outer circumference of a pipe, and comprises a first thermal insulation layer, a reflective layer disposed outside the first thermal insulation layer, a second thermal insulation layer disposed outside the reflective layer, and a heater wire disposed inside the first thermal insulation layer. With this thermal insulation structure, power consumption in the heater wire is reduced, and the pipe is sufficiently heated. In addition, because the second thermal insulation layer is located outside the reflective layer, the outer surface of the thermal insulation structure can be cooled to an appropriate temperature. As a result, workability around the jacket heater can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing how the jacket heater proposed in this disclosure is attached to piping. [Figure 2] This is a cross-sectional view obtained along the line II-II shown in Figure 1. [Figure 3A] This diagram illustrates an example of stitching around a third sensor passage hole formed in the reflective layer, and is a schematic diagram showing the view from the reflective layer side to the first insulating layer side in the thickness direction of the jacket heater. [Figure 3B] This diagram illustrates another example of stitching around a third sensor passage hole formed in the reflective layer, and is a schematic diagram showing the view from the reflective layer side to the first insulating layer side in the thickness direction of the jacket heater. [Figure 4] This is a perspective view showing another example of a through hole formed in the reflective layer. [Modes for carrying out the invention]

[0009] The jacket heater proposed in this disclosure will be described below. In this specification, as an example, the jacket heater 10 shown in Figure 1, etc., will be described.

[0010] As shown in Figure 1, the jacket heater 10 covers the pipe 90. By heating the pipe 90, the jacket heater 10 prevents the gas flowing inside the pipe 90 from condensing or precipitation.

[0011] As shown in Figure 2, the jacket heater 10 has a heater wire 14 and a heater wire base material 18 to which the heater wire 14 is attached. The heater wire 14 is, for example, a nickel-chromium metal resistor. As the heater wire base material 18, for example, an inorganic fiber cloth made of inorganic fibers such as glass fiber, silica fiber, alumina fiber, or silica-alumina fiber can be used. The heater wire 14 is sewn onto the heater wire base material 18. The heater wire 14 is connected to an external power supply via lead wires 14b.

[0012] As shown in Figure 2, the jacket heater 10 has a first insulation layer 11 and a second insulation layer 12. The first insulation layer 11 is located outside the heater wire 14 and the heater wire base material 18 and covers them. The second insulation layer 12 is located further outside the first insulation layer 11 and covers the first insulation layer 11.

[0013] The first insulation layer 11 and the second insulation layer 12 are formed from, for example, an inorganic fiber insulation material. The inorganic fiber may be, for example, glass fiber, ceramic fiber, or silica fiber. Alternatively, the first insulation layer 11 and the second insulation layer 12 may be inorganic or organic insulation materials containing polyimide or silica, having voids with an average void width of less than or equal to a certain value (for example, voids with an average void width smaller than the mean free path of air molecules). The materials of the first insulation layer 11 and the second insulation layer 12 may be the same or different.

[0014] The first insulation layer 11 may consist of a single layer or multiple layers stacked on top of each other. Similarly, the second insulation layer 12 may consist of a single layer or multiple layers stacked on top of each other. If each insulation layer 11 and 12 consists of multiple layers, they may be made of the same material or different materials.

[0015] The thickness of the first insulation layer 11 may be, for example, 5 mm to 100 mm. The thickness of the second insulation layer 12 may also be 5 mm to 100 mm. With such thicknesses, insulation performance can be ensured while keeping the space required for installing the jacket heater 10 down. Preferably, the thickness of the first insulation layer 11 may be 5 mm to 50 mm. More preferably, the thickness of the first insulation layer 11 may be 8 mm to 30 mm. The thickness of the second insulation layer 12 may also be 5 mm to 50 mm. More preferably, the thickness of the second insulation layer 12 may be 8 mm to 30 mm.

[0016] As shown in Figure 2, the jacket heater 10 has a reflective layer 13 positioned between the first insulation layer 11 and the second insulation layer 12. This allows heat (electromagnetic waves) emitted from the piping 90 and heater wire 14 to be reflected by the reflective layer 13. As a result, the piping 90 is heated efficiently. Furthermore, because the second insulation layer 12 is located outside the reflective layer 13, the outer surface of the jacket heater 10 can be cooled to an appropriate temperature. Consequently, workability around the jacket heater 10 can be improved.

[0017] The reflective layer 13 is desirably made of a material having high reflectivity for infrared rays. The material of the reflective layer 13 is, for example, metal. Aluminum is suitable as the material of the reflective layer 13, but other metals such as copper and stainless steel may also be used. Further, the reflective layer 13 may be formed of a non-metallic material such as ceramic, silicon carbide, or zirconia.

[0018] The reflective layer 13 is, for example, a metal foil having a thickness of 10 µm to 700 µm. With this thickness, unintended breakage of the reflective layer 13 can be prevented while maintaining the flexibility of the reflective layer 13. The thickness of the reflective layer 13 is preferably 10 µm to 200 µm.

[0019] As shown in FIG. 1, the reflective layer 13 may be formed over substantially the entire circumference of the pipe 90. That is, the reflective layer 13 may surround the pipe 90 over substantially 360 degrees. Further, the reflective layer 13 may be provided over substantially the entire length of the jacket heater 10 in the longitudinal direction of the pipe 90.

[0020] As shown in FIG. 2, the jacket heater 10 has an inner skin 16 provided inside the heater wire base material 18. An insulating layer 15 for reliably insulating the heater wire 14 from the pipe 90 may be disposed between the inner skin 16 and the heater wire base material 18. Further, the jacket heater 10 has an outer skin 17 that covers the outside of the second heat insulating layer 12.

[0021] As the outer skin 17 and the inner skin 16, for example, heat-resistant sheets (including cloths) can be used. The material of the outer skin 17 and the material of the inner skin 16 may be the same or different. For the outer skin 17 and the inner skin 16, for example, a porous sheet, an inorganic fiber sheet, a resin sheet, or the like can be used. An example of the porous sheet is a sheet of PTFE (polytetrafluoroethylene). Glass cloth can be cited as an example of the inorganic fiber sheet. The resin sheet is, for example, a fluororesin sheet. Further, the inorganic fiber sheet may be coated with silicon or fluorine.

[0022] The jacket heater 10 has flexibility. That is, each of the heat insulating layers 11 and 12, the reflective layer 13, the outer skin 17, the inner skin 16, the heater wire 14, and the heater wire base material 18 constituting the jacket heater 10 has flexibility. The jacket heater 10 is formed into a cylindrical shape by being wound around the outside of the pipe 90 in the installation process.

[0023] The jacket heater 10 has a fixing member that fixes the jacket heater 10 in a state where the jacket heater 10 is wound around the pipe 90. As the fixing member, the jacket heater 10 has, for example, a plurality of hook-and-loop fasteners 22 (see FIG. 1) arranged along one edge of the jacket heater 10. The hook-and-loop fasteners 22 may be attached to the outer surface of the jacket heater 10. The hook-and-loop fasteners 22 are attached to the opposite edge of the jacket heater 10 in a state where the jacket heater 10 is wound around the pipe 90. Note that the fixing member is not limited to the hook-and-loop fasteners 22. The fixing member may be constituted by, for example, hooks, or may include a belt wound around the outside of the jacket heater 10.

[0024] [Lead wire passage hole] As shown in FIG. 2, a first lead wire passage hole 11b is formed in the first heat insulating layer 11. A second lead wire passage hole 12b is formed in the second heat insulating layer 12. A third lead wire passage hole 13b is formed in the reflective layer 13. The lead wire passage holes 11b, 12b, 13b penetrate the heat insulating layers 11, 12 and the reflective layer 13 in the thickness direction thereof. The positions of the first, second, and third lead wire passage holes 11b, 12b, 13b in the length direction and the circumferential direction of the pipe 90 may be substantially the same. That is, when the jacket heater 10 is viewed in the thickness direction, a part of the second lead wire passage hole 12b and a part of the third lead wire passage hole 13b may overlap the first lead wire passage hole 11b. The first, second, and third lead wire passage holes 11b, 12b, 13b may constitute one passage hole extending in the thickness direction of the jacket heater 10.

[0025] As shown in Figure 2, a lead wire 14b is connected to the heater wire 14. The lead wire 14b extends from the heater wire 14, through the first lead wire passage hole 11b, the third lead wire passage hole 13b, and the second lead wire passage hole 12b, to the outside of the second insulation layer 12.

[0026] The lead wire 14b may extend to the outside of the jacket heater 10 by passing through an opening 17a formed in the outer sheath 17. The heater wire 14 may be connected to an external power source (a control device that controls the current supplied to the heater wire 14) via the lead wire 14b. In the example shown in Figure 2, the lead wire 14b extends to the outside of the jacket heater 10 by passing through an opening 17a that penetrates the outer sheath 17 in the thickness direction of the outer sheath 17 (radial direction of the pipe 90). Alternatively, the lead wire 14b may extend to the outside of the jacket heater 10 through a gap formed in the edge of the outer sheath 17.

[0027] Two lead wires 14b may be connected to the heater wire 14. These two lead wires 14b may pass through common lead wire passage holes 11b, 12b, and 13b in that order and extend to the outside of the second insulation layer 12. Alternatively, each of the two lead wires 14b may have its own separate lead wire passage holes 11b, 12b, and 13b. That is, the lead wire passage holes 11b, 12b, and 13b through which the first lead wire 14b passes may be formed in the first insulation layer 11, the second insulation layer 12, and the reflective layer 13, while the lead wire passage holes 11b, 12b, and 13b through which the second lead wire 14b passes may be formed in the first insulation layer 11, the second insulation layer 12, and the reflective layer 13.

[0028] The third lead wire passage hole 13b may be formed inside the outer edge of the reflective layer 13. That is, the inner edge of the third lead wire passage hole 13b may be annular, surrounding the lead wire 14b. Similarly, the first and second lead wire passage holes 11b and 12b may be formed inside the outer edges of the insulating layers 11 and 12. That is, the inner edges of the first and second lead wire passage holes 11b and 12b may be annular, surrounding the lead wire 14b.

[0029] In contrast, the third lead wire passage hole 13b may be a recess formed on the outer periphery of the reflective layer 13. Similarly, the first and second lead wire passage holes 11b and 12b may be recesses formed on the outer periphery of the heat insulating layers 11 and 12. Furthermore, the positions of these recesses in the longitudinal and circumferential directions of the piping 90 may be substantially the same.

[0030] The size of the third lead wire passage hole 13b is larger than the sizes of the first and second lead wire passage holes 11b and 12b, respectively. Specifically, the diameter Rb of the third lead wire passage hole 13b (see Figure 2) is larger than the diameters of the first and second lead wire passage holes 11b and 12b, respectively. As a result, the positional change of the lead wire 14b inside the third lead wire passage hole 13b is restricted by the lead wire passage holes 11b and 12b. Consequently, contact between the lead wire 14b and the reflective layer 13 is suppressed. In this way, even if the outer sheath of the lead wire 14b is broken, for example, charging of the reflective layer 13 due to the current from the lead wire 14b to the reflective layer 13 can be prevented.

[0031] The size of each lead wire passage hole 11b, 12b, and 13b may be the diameter of the passage hole if they are circular. If they are rectangular, the size of each lead wire passage hole 11b, 12b, and 13b may be the width of one side of the inner edge of the passage hole. The first and second lead wire passage holes 11b and 12b may be located in the center of the third lead wire passage hole 13b.

[0032] Unlike the example shown in Figure 2, the diameter Rb of the third lead wire passage hole 13b may be larger than the diameter of one of the two lead wire passage holes 11b and 12b, but the same as or smaller than the diameter of the other lead wire passage hole 11b and 12b. For example, the diameter Rb of the third lead wire passage hole 13b may be larger than the diameter of the first lead wire passage hole 11b, but the same as or smaller than the diameter of the second lead wire passage hole 12b. Even in this case, the positional change of the lead wire 14b inside the third lead wire passage hole 13b is restricted by the first lead wire passage hole 11b.

[0033] The shape of the third lead wire passage hole 13b may be, for example, rectangular. In this case, the width of one side of the inner edge of the third lead wire passage hole 13b may be greater than the width of one side of the inner edge of the lead wire passage holes 11b and 12b.

[0034] The diameters of the lead wire passage holes 11b and 12b formed in the heat insulating layers 11 and 12 may correspond to the thickness of the lead wire 14b. In other words, the heat insulating layers 11 and 12 may be in contact with the lead wire 14b on the inner surfaces of the lead wire passage holes 11b and 12b. This allows for more effective suppression of positional changes of the lead wire 14b inside the third lead wire passage hole 13b.

[0035] Note that the diameters of the first lead wire passage hole 11b and the second lead wire passage hole 12b may be different. For example, the diameter of the first lead wire passage hole 11b may correspond to the thickness of the lead wire 14b, and the inner surface of the first lead wire passage hole 11b may be in contact with the lead wire 14b, while the diameter of the second lead wire passage hole 12b may be larger than the thickness of the lead wire 14b (in this case, the diameter of the first lead wire passage hole 11b). This makes it easier to pass the lead wire 14b through the second lead wire passage hole 12b. Note that the relationship between the sizes of the lead wire passage holes 11b and 12b may be the reverse of the example described here.

[0036] It is desirable that the distance from the inner edges of the lead wire passage holes 11b and 12b to the inner edge of the third lead wire passage hole 13b be 3 mm or more. It is even more desirable that this distance be 5 mm or more. This effectively prevents contact between the lead wire 14b and the reflective layer 13.

[0037] [Sensor pass-through hole] As shown in Figure 2, the jacket heater 10 has a sensor 19. The sensor 19 has a temperature sensing element 19A. Specifically, the sensor 19 is a thermocouple. In this case, the temperature sensing element 19A is a part that has two strands (not shown) made of different materials inside. The temperature sensing element 19A holds the two strands in an insulated state. The temperature sensing element 19A may have a sheath made of metal on its surface, and the strands may be arranged inside it. The number of strands in the temperature sensing element 19A may be more than two.

[0038] The tip 19e of the temperature sensing element 19A is located inside the first insulation layer 11. The tip 19e of the temperature sensing element 19A may be exposed inside the inner sheath 16 and in direct contact with the outer surface of the piping 90. The sensor 19 has a lead wire 19b and may be connected via the lead wire 19b to an external device (for example, a control device that controls the current supplied to the heater wire 14).

[0039] As shown in Figure 2, a first sensor pass-through hole 11a is formed in the first insulation layer 11. A second sensor pass-through hole 12a is formed in the second insulation layer 12. A third sensor pass-through hole 13a is formed in the reflective layer 13. The sensor pass-through holes 11a, 12a, and 13a penetrate the insulation layers 11, 12 and the reflective layer 13 in their respective thickness directions. The positions of the first, second, and third sensor pass-through holes 11a, 12a, and 13a in the longitudinal and circumferential directions of the piping 90 may be substantially the same. That is, when the jacket heater 10 is viewed in the thickness direction, a portion of the second sensor pass-through hole 12a and a portion of the third sensor pass-through hole 13a may overlap with the first sensor pass-through hole 11a. As a result, the first, second, and third sensor pass-through holes 11a, 12a, and 13a may constitute a single pass-through hole extending in the thickness direction of the jacket heater 10.

[0040] As shown in Figure 2, the sensor 19 extends from the tip 19e of the temperature-sensing part 19A located inside the first heat insulating layer 11, through the first sensor passage hole 11a, the third sensor passage hole 13a, and the second sensor passage hole 12a in that order, to the outside of the second heat insulating layer 12. Passage holes for the sensor 19 may also be formed in members located inside the first heat insulating layer 11, such as the inner skin 16.

[0041] As shown in Figure 2, the temperature-sensing part 19A may have a first portion 19g located inside the inner skin 16, a second portion 19h located inside the sensor passage holes 11a, 12a, and 13a, and a third portion 19i located outside the second insulation layer 12. The second portion 19h may be bent relative to the first portion 19g, and the third portion 19i may be bent relative to the second portion 19h. The third portion 19i may extend between the second insulation layer 12 and the outer skin 17 in the longitudinal direction of the pipe 90 or in the circumferential direction of the pipe 90. The temperature-sensing part 19A may be flexible to allow for such bending.

[0042] As shown in Figure 2, the temperature sensing element 19A and the lead wire 19b may be connected to each other at a location outside the second insulation layer 12. The lead wire 19b may extend to the outside of the jacket heater 10 from an opening 17a formed in the outer sheath 17. In the example shown in Figure 2, the lead wire 19b and the lead wire 14b extending from the heater wire 14 extend to the outside of the jacket heater 10 from a common opening 17a. However, the lead wire 19b and the lead wire 14b may extend to the outside of the jacket heater 10 from separate openings.

[0043] Furthermore, unlike the example shown in Figure 2, the entire temperature-sensing element 19A may be placed inside the first heat-insulating layer 11. In this case, lead wires 19b may be passed through the inside of the sensor passage holes 11a, 12a, and 13a.

[0044] The size of the third sensor passage hole 13a is larger than the sizes of the first and second sensor passage holes 11a and 12a, respectively. Specifically, as shown in Figure 2, the diameter Ra of the third sensor passage hole 13a is larger than the diameters of the first and second sensor passage holes 11a and 12a, respectively. As a result, the positional change of the sensor 19 inside the third sensor passage hole 13a is restricted by the sensor passage holes 11a and 12a. Consequently, contact between the sensor 19 and the reflective layer 13 is suppressed. In this way, even if the reflective layer 13 becomes charged, it is possible to prevent that electricity from flowing through the sensor 19 to the piping 90.

[0045] Here, the size of the sensor through holes 11a, 12a, and 13a may be the diameter of the through hole if they are circular. If they are rectangular, the size of the sensor through holes 11a, 12a, and 13a may be the width of one side of the inner edge of the through hole.

[0046] Furthermore, it is desirable that the distance from the inner edges of the through holes 11a and 12a to the inner edge of the third sensor through hole 13a be 3 mm or more. It is even more desirable that this distance be 5 mm or more. This effectively prevents contact between the sensor 19 and the reflective layer 13.

[0047] Unlike the example shown in Figure 2, the diameter Ra of the third sensor passage hole 13a may be larger than the diameter of one of the first and second sensor passage holes 11a and 12a, but the same as or smaller than the diameter of the other sensor passage hole 11a and 12a. For example, the diameter Ra of the third sensor passage hole 13a may be larger than the diameter of the first sensor passage hole 11a, but the same as or smaller than the diameter of the second sensor passage hole 12a. Even in this case, the positional change of the sensor 19 inside the third sensor passage hole 13a can be restricted by the first sensor passage hole 11a.

[0048] The shape of the third sensor passage hole 13a may be, for example, rectangular. In this case, the width of one side of the inner edge of the third sensor passage hole 13a may be greater than the width of one side of the inner edge of the sensor passage holes 11a and 12a.

[0049] The diameters of the sensor passage holes 11a and 12a formed in the heat insulating layers 11 and 12 may correspond to the thickness of the sensor 19. That is, the heat insulating layers 11 and 12 may be in contact with the sensor 19 (for example, the temperature sensing part 19A) on the inner surfaces of the sensor passage holes 11a and 12a. This allows for more effective suppression of positional changes of the sensor 19 inside the third sensor passage hole 13a.

[0050] The diameters of the first sensor passage hole 11a and the second sensor passage hole 12a may be different. For example, the diameter of the first sensor passage hole 11a may correspond to the thickness of the sensor 19 (e.g., the temperature sensing element 19A), and the inner surface of the first sensor passage hole 11a may be in contact with the sensor 19, while the diameter of the second sensor passage hole 12a may be larger than the thickness of the sensor 19 (in this case, the diameter of the first sensor passage hole 11a). This makes it easier to pass the sensor 19 through the second sensor passage hole 12a. The relationship between the sizes of the sensor passage holes 11a and 12a may be the reverse of the example described here.

[0051] As shown in Figure 2, the third sensor passage hole 13a may be formed inside the outer edge of the reflective layer 13. That is, the inner edge of the third sensor passage hole 13a may be annular, surrounding the sensor 19. Similarly, the first and second sensor passage holes 11a and 12a may be formed inside the outer edges of the heat insulating layers 11 and 12.

[0052] Unlike the example shown in Figure 2, the third sensor passage hole 13a may be a recess formed on the outer edge of the reflective layer 13. Similarly, the first and second sensor passage holes 11a and 12a may be recesses formed on the outer edges of the heat insulating layers 11 and 12. Furthermore, the positions of these recesses in the longitudinal and circumferential directions of the piping 90 may be substantially the same.

[0053] [Seaming the reflective layer and the insulating layer] The heat insulating layers 11 and 12 and the reflective layer 13 may be sewn together with heat-resistant thread. Examples of heat-resistant threads that can be used include glass yarn, silica yarn, alumina yarn, and even those coated with fluororesin.

[0054] As shown in Figures 3A and 3B, the area around the third sensor passage hole 13a may be surrounded by thread 31a. That is, the reflective layer 13 and the first heat insulating layer 11 may be sewn together by the thread 31a surrounding the third sensor passage hole 13a. This effectively suppresses misalignment between the third sensor passage hole 13a and the first sensor passage hole 11a. As a result, contact between the sensor 19 and the reflective layer 13 is more effectively suppressed.

[0055] As shown in Figure 3A, the thread 31a may include a portion located inside the inner edge of the third sensor passage hole 13a and a portion located outside the inner edge of the third sensor passage hole 13a. Alternatively, as shown in Figure 3B, the entire thread 31a surrounding the third sensor passage hole 13a may be located only outside the inner edge of the third sensor passage hole 13a.

[0056] The area around the third lead wire passage hole 13b through which the lead wire 14b of the heater wire 14 passes may also be sewn together with thread 31a, similar to Figures 3A and 3B. That is, the reflective layer 13 and the first heat insulating layer 11 may be sewn together with thread 31a surrounding the third lead wire passage hole 13b.

[0057] The reflective layer 13 may also be sewn to the first insulating layer 11 at other locations using heat-resistant thread. The locations of these sewn seams may be along the outer edge of the reflective layer 13, surrounding the entire reflective layer 13, or they may be provided only at multiple locations inside the outer edge of the reflective layer 13. The second insulating layer 12 may also be sewn to the first insulating layer 11 and the reflective layer 13 with thread. Furthermore, to increase the strength of the seams, the first insulating layer 11 and the reflective layer 13 may also be sewn to the heater wire base material 18 to which the heater wire 14 is sewn, and to the inner sheath 16 with thread.

[0058] [Common passage hole] Note that the structure of each lead wire passage hole 11b to 13b and each sensor passage hole 11a to 13a is not limited to the examples shown in Figure 2, etc.

[0059] Figure 4 shows a modified example of the through-hole. In the example shown in this figure, a lead wire through-hole 13c is formed in the reflective layer 13. When the jacket heater 10 is viewed from above (when the through-hole 13c is viewed in the radial direction of the piping 90), the sensor through-holes 11a and 12a and the lead wire through-holes 11b and 12b are located inside the lead wire through-hole 13c. Therefore, the lead wire 14b of the heater wire 14 extends to the outside of the heat insulating layer 12 by passing through the lead wire through-holes 11b and 12b and the lead wire through-hole 13c. The sensor 19 also extends to the outside of the heat insulating layer 12 by passing through the sensor through-holes 11a and 12a and the lead wire through-hole 13c. This structure reduces the number of through-holes formed in the reflective layer 13. As a result, the manufacturing process of the reflective layer 13 can be reduced.

[0060] The size of the lead wire passage hole 13c is larger than the size of the sensor passage holes 11a and 12a and the lead wire passage holes 11b and 12b. For example, it is desirable that the distance from the inner edge of the lead wire passage hole 13c to the inner edges of the passage holes 11a, 12a, 11b, and 12b be 3 mm or more. This distance may preferably be 5 mm or more. This suppresses contact between the lead wire 14b and the reflective layer 13. Furthermore, even if the outer sheath of the lead wire 14b is broken, it is possible to prevent electricity from flowing from the lead wire 14b to the reflective layer 13 and causing the reflective layer 13 to become charged. In addition, contact between the sensor 19 and the reflective layer 13 is suppressed. In this way, even if the reflective layer 13 becomes charged, it is possible to prevent that electricity from flowing through the sensor 19 to the piping 90.

[0061] [thermostat] As shown in Figure 2, the jacket heater 10 may have a thermostat 21. The thermostat 21 may be connected to the heater wire 14 via lead wires (not shown), or to an external power source (a control device that supplies current to the heater wire 14). The thermostat 21 turns off when it detects overheating of the heater wire 14, stopping the current to the heater wire 14.

[0062] As shown in Figure 2, a housing chamber 12d for housing a thermostat 21 may be formed in the second insulation layer 12. The thermostat 21 may be placed outside the reflective layer 13. With this arrangement of the thermostat 21, the temperature of the thermostat 21 will be lower than the temperature of the inner surface of the jacket heater 10 where the heater wires 14 are located, and the temperature of the piping 90. As a result, even if it is necessary to increase the output of the jacket heater 10 to raise the temperature of the piping 90, a small thermostat with a low operating temperature (the temperature at which the current is cut off) can be used as the thermostat 21 to prevent the jacket heater 10 from overheating. For example, if the temperature of the piping rises to 300°C due to heating by the jacket heater, a large thermostat with an operating temperature set to 300°C or higher is usually required. However, in the jacket heater 10 proposed in this disclosure, the thermostat 21 is located outside the reflective layer 13, so the ambient temperature around the thermostat 21 does not reach 300°C. Therefore, a thermostat with an operating temperature lower than 300°C (for example, a small thermostat with an operating temperature of about 200°C) can be used as the thermostat 21, and the piping 90 can be heated to a temperature sufficiently higher than its operating temperature (300°C in the example described here).

[0063] Unlike the example shown in Figure 2, the thermostat 21 may be located inside the reflective layer 13.

[0064] [Manufacturing method for jacket heaters] An example of a manufacturing method for the jacket heater 10 will be described. The worker prepares a first insulation layer 11 and a second insulation layer 12. The worker forms a first lead wire passage hole 11b and a first sensor passage hole 11a in the first insulation layer 11, and a second lead wire passage hole 12b and a second sensor passage hole 12a in the second insulation layer 12. The worker also prepares a reflective layer 13 and forms a third lead wire passage hole 13b and a third sensor passage hole 13a in it. At this time, a lead wire passage hole 13c may be formed in the reflective layer 13, as shown in Figure 4.

[0065] The worker sews the first insulation layer 11, the reflective layer 13, and the second insulation layer 12 together with heat-resistant thread 31a. At this time, the worker may sew the first insulation layer 11 and the reflective layer 13 together, and then sew the second insulation layer 12 to the first insulation layer 11 and the reflective layer 13. As another example, the worker may sew the first insulation layer 11, the reflective layer 13, and the second insulation layer 12 together. The worker also sews the heater wire 14 to the heater wire base material 18. At this time, the worker may sew the insulating layer 15 to the heater wire 14 and the heater wire base material 18.

[0066] Next, the worker passes the lead wire 14b of the heater wire 14 through the lead wire passing holes 11b, 12b, and 13b and leads it out to the outside of the second insulation layer 12. Next, the worker covers the inside of the heater wire 14, the insulating layer 15, and the heater wire base material 18 with the inner sheath 16. Then, the worker passes the sensor 19 through the inner sheath 16, the insulating layer 15, and the holes formed in the heater wire base material 18, and further through the sensor passing holes 11a, 13a, and 12a to lead it out to the outside of the second insulation layer 12. Then, the worker covers the outside of the second insulation layer 12 with the outer sheath 17 and leads the lead wires 14b and 19b through the opening 17a formed in the outer sheath 17 to the outside of the jacket heater 10. Then, the worker sews the inner sheath 16 and the outer sheath 17 together and houses the heater wire 14, the first insulation layer 11, etc. inside them.

[0067] [summary] (1) The jacket heater 10 has a first insulation layer 11, a reflective layer 13 located outside the first insulation layer 11, a second insulation layer 12 located outside the reflective layer 13, and a heater wire 14 located inside the first insulation layer 11. Because the jacket heater 10 has a reflective layer 13, it can sufficiently heat the piping 90 while keeping power consumption down. Also, because the second insulation layer 12 is located outside the reflective layer 13, the outer surface of the jacket heater 10 can be cooled to an appropriate temperature. As a result, workability around the jacket heater 10 can be improved.

[0068] (2) In the structure of (1), a lead wire 14b may be connected to the heater wire 14. A first lead wire passage hole 11b may be formed in the first heat insulating layer 11, a second lead wire passage hole 12b may be formed in the second heat insulating layer 12, and a third lead wire passage hole 13b (or passage hole 13c, Figure 4) may be formed in the reflective layer 13. The lead wire 14b may pass through the first lead wire passage hole 11b, the third lead wire passage hole 13b (or passage hole 13c), and the second lead wire passage hole 12b to the outside of the second heat insulating layer 12. The size of the third lead wire passage hole 13b (or passage hole 13c) may be larger than the size of at least one of the first lead wire passage hole 11b and the second lead wire passage hole 12b. With this structure, contact between the lead wire 14b connected to the heater wire 14 and the conductive reflective layer 13 is suppressed. As a result, charging of the reflective layer 13 can be prevented.

[0069] (3) In the structure of (1) or (2), the jacket heater 10 may have a sensor 19 having a temperature sensing part 19A, at least at its tip 19e located inside the first heat insulating layer 11. A fourth sensor pass-through hole may be formed in the first heat insulating layer 11, a second sensor pass-through hole 12a may be formed in the second heat insulating layer 12, and a third sensor pass-through hole 13a (or pass-through hole 13c, Figure 4) may be formed in the reflective layer 13. The sensor 19 may extend from its tip 19e, through the first sensor pass-through hole 11a, the third sensor pass-through hole 13a (or pass-through hole 13c), and the second sensor pass-through hole 12a to the outside of the second heat insulating layer 12. The size of the third sensor pass-through hole 13a (or pass-through hole 13c) may be larger than the size of at least one of the first sensor pass-through hole 11a and the second sensor pass-through hole 12a. This structure prevents the sensor 19 from coming into contact with the conductive reflective layer 13. As a result, even if the reflective layer 13 becomes charged, the flow of that electricity through the sensor 19 to the piping is suppressed.

[0070] In the structure of (4)(2), the jacket heater 10 may have a sensor 19 having a temperature sensing part 19A, at least at its tip 19e located inside the first heat insulating layer 11. The first heat insulating layer 11 may have a first sensor pass-through hole 11a, and the second heat insulating layer 12 may have a second sensor pass-through hole 12a. The sensor 19 may extend from its tip 19e through the first sensor pass-through hole 11a, the lead wire pass-through hole 13c (see Figure 4), and the second sensor pass-through hole 12a to the outside of the second heat insulating layer 12. With this structure, since the sensor 19 and the lead wire 14b pass through the same pass-through hole 13c, the number of pass-through holes formed in the reflective layer 13 is reduced. As a result, the manufacturing process of the reflective layer 13 can be reduced.

[0071] (5) In the structure of (2), the size of at least one of the first lead wire passage hole 11b and the second lead wire passage hole 12b may correspond to the thickness of the lead wire 14b. With this structure, the positional change of the lead wire 14b inside the third lead wire passage hole 13b is suppressed more effectively. As a result, contact between the reflective layer 13 and the lead wire 14b is suppressed more effectively.

[0072] In the structure of (6)(3), the size of at least one of the first sensor passage hole 11a and the second sensor passage hole 12a may correspond to the thickness of the sensor 19. With this structure, the positional change of the sensor 19 inside the third sensor passage hole 13a is suppressed more effectively. As a result, contact between the reflective layer 13 and the sensor 19 is suppressed more effectively.

[0073] In the structure of (7)(2) or (5), the first heat insulating layer 11 and the reflective layer 13 may be sewn together with heat-resistant thread 31a (Figures 3A and 3B). The thread 31a may surround the third lead wire passage hole 13b. This structure suppresses the misalignment of the relative positions of the third lead wire passage hole 13b and the lead wire passage holes 11b and 12b. As a result, contact between the reflective layer 13 and the lead wire 14b is more effectively suppressed.

[0074] In the structure of (8)(3) or (6), the first heat insulating layer 11 and the reflective layer 13 may be sewn together with heat-resistant thread 31a (Figures 3A and 3B). The thread 31a surrounds the third sensor passage hole 13a. This structure suppresses the misalignment of the relative position between the third sensor passage hole 13a and the sensor passage holes 11a and 12a. As a result, contact between the reflective layer 13 and the lead wire 14b is more effectively suppressed.

[0075] (9) A method for manufacturing a jacket heater 10 to be attached to the outer circumference of a pipe 90 includes the steps of sewing together a first heat insulating layer 11 to cover the heater wire 14, a reflective layer 13 to cover the outside of the first heat insulating layer 11, and a second heat insulating layer 12 to cover the outside of the reflective layer 13, and sewing the heater wire 14 to the first heat insulating layer 11.

[0076] (10) The thermal insulation structure for attachment to the outer circumference of the pipe 90 includes a first thermal insulation layer 11, a reflective layer 13 located outside the first thermal insulation layer 11, a second thermal insulation layer 12 located outside the reflective layer 13, and a heater wire 14 located inside the first thermal insulation layer 11.

[0077] The jacket heater proposed in this disclosure is not limited to the examples described above, and various modifications may be made. For example, the jacket heater may have multiple thermal insulation structures, each of which may include a first thermal insulation layer 11, a reflective layer 13, and a second thermal insulation layer 12.

Claims

1. A jacket heater for mounting on the outer circumference of a pipe, The first insulation layer, A heater wire located inside the first insulation layer, A reflective layer is placed on the outside of the first insulation layer and reflects the heat emitted from the piping and the heater wire, A second insulating layer is located outside the aforementioned reflective layer. A jacket heater that has this feature.

2. Lead wires are connected to the aforementioned heater wire. The first insulation layer has a hole for passing the first lead wire. The second insulation layer has a hole for passing the second lead wire. The reflective layer has a hole for passing the third lead wire. The reflective layer is conductive, The lead wires extend to the outside of the second insulation layer, passing through the first lead wire passage hole, the third lead wire passage hole, and the second lead wire passage hole. The size of the third lead wire passage hole is larger than the size of at least one of the first lead wire passage hole and the second lead wire passage hole. A jacket heater as described in claim 1.

3. The sensor has a temperature-sensing portion, at least the tip of which is located inside the first heat insulating layer, The first heat insulating layer has a first sensor passage hole formed therein. The second heat insulating layer has a hole for passing the second sensor. A third sensor pass-through hole is formed in the reflective layer. The reflective layer is conductive, The sensor extends from its tip through the first sensor passage hole, the third sensor passage hole, and the second sensor passage hole to the outside of the second heat insulating layer. The size of the third sensor passage hole is larger than the size of at least one of the first sensor passage hole and the second sensor passage hole. A jacket heater as described in claim 1 or 2.

4. The sensor has a temperature-sensing portion, at least the tip of which is located inside the first heat insulating layer, The first heat insulating layer has a first sensor passage hole formed therein. The second heat insulating layer has a hole for passing the second sensor. The sensor extends from its tip through the first sensor passage hole, the third lead wire passage hole, and the second sensor passage hole to the outside of the second heat insulating layer. A jacket heater as described in claim 2.

5. The size of at least one of the first lead wire passage hole and the second lead wire passage hole corresponds to the thickness of the lead wire. A jacket heater as described in claim 2.

6. The size of at least one of the first sensor passage hole and the second sensor passage hole corresponds to the thickness of the sensor. A jacket heater as described in claim 3.

7. The first insulating layer and the reflective layer are sewn together with heat-resistant thread. The aforementioned thread surrounds the periphery of the third lead wire passage hole. A jacket heater as described in claim 2 or 5.

8. The first insulating layer and the reflective layer are sewn together with heat-resistant thread. The aforementioned thread surrounds the periphery of the third sensor passage hole. A jacket heater as described in claim 3.

9. A method for manufacturing a jacket heater to be attached to the outer circumference of a pipe, A process of sewing together a first insulating layer for covering the heater wire, a reflective layer covering the outside of the first insulating layer, and a second insulating layer covering the outside of the reflective layer, and Step of sewing the heater wire to the first insulation layer. including A method for manufacturing a jacket heater.

10. An insulating structure for attachment to the outer circumference of a pipe, The first insulation layer, A heater wire located inside the first insulation layer, A reflective layer is placed on the outside of the first insulation layer and reflects the heat emitted from the piping and the heater wire, A second insulating layer is located outside the aforementioned reflective layer. An insulating structure that has this feature.

Images