JP3194830U - Freezing prevention structure - Google Patents

Abstract

An anti-freezing structure capable of heating a pipe more uniformly using a PTC heater wire is provided. A freezing prevention structure 1A includes at least a pipe 80 through which water flows and a PTC heater wire 30 attached to the pipe 80, and prevents freezing of water flowing into the pipe 80. The PTC heater wire 30 includes a plurality of heating elements 13, 13,... Having a positive temperature coefficient characteristic that are connected in parallel between the pair of power supply lines 11, 12. Are connected to the pair of power supply lines 11 and 12 at equal intervals along the longitudinal direction of the pair of power supply lines 11 and 12. The PTC heater wire 30 is attached to the outer wall surface of the pipe 30 so that the pair of power supply lines 11 and 12 are along the direction in which the water in the pipe 30 flows. [Selection] Figure 7

Description

  The present invention relates to a freeze prevention structure using a PTC heater wire having a positive temperature coefficient characteristic.

  Conventionally, a PTC heater wire having a heating element having a positive temperature coefficient (PTC) characteristic has been known, and since it is flexible and easy to lay, it is widely used for applications such as snow melting and prevention of freezing of water pipes. It is used. Here, the PTC characteristic is an acronym for Positive Temperature Coefficient, which means that the electrical resistance changes by a positive coefficient as the temperature increases.

  For example, in Patent Document 1, a pair of long power supply lines, a heating element having a plurality of positive temperature coefficient characteristics connected in parallel between the pair of power supply lines, and the power supply line and the heating element are surrounded. An anti-freezing PTC heater wire having a covering material made of an insulating material is described. Here, the PTC heater wire is used by being spirally wound around a pipe through which water flows, such as a water pipe, and is configured as a part of the freeze prevention structure.

Japanese Patent Laid-Open No. 08-41936

  However, it is difficult to wind the PTC heater wire spirally at the same pitch around the pipe, and it is extremely difficult to wind the PTC heater wire at an equal pitch around the bent portion of the pipe. As a result, temperature unevenness occurs in the pipe heated by the PTC heater wire. Since the pipe having the temperature unevenness has a local thermal expansion difference, the winding of the PTC heater wire around the pipe is easy to loosen, and the non-uniform heating of the pipe by the PTC heater wire is promoted.

  This invention is made in view of such a point, and is providing the freezing prevention structure which can heat piping more uniformly using a PTC heater wire.

  In view of such a problem, the antifreezing structure according to the present invention includes at least a pipe through which water flows and a PTC heater wire attached to the pipe, and the freezing that prevents freezing of water flowing into the pipe. A PTC heater wire, a plurality of heating elements having a positive temperature coefficient characteristic connected in parallel between the pair of power supply lines, and a pair of power supply lines arranged in parallel; A pair of power supply lines and a covering material made of an insulating material surrounding the heat generating element, and the plurality of heat generating elements are arranged at equal intervals along the longitudinal direction of the pair of power supply lines. The PTC heater wire is connected to a power supply line, and is attached to an outer wall surface of the pipe so that the pair of power supply lines are along a direction in which water of the pipe flows.

  According to the anti-freezing structure of the present invention, since the pair of power supply lines of the PTC heater wire is attached to the outer wall surface of the pipe so as to follow the direction of water flow, the PTC heater is equally spaced in the direction of water flow of the pipe. Wire heating elements can be arranged. Thereby, compared with the case where the PTC heater wire is wound around the pipe spirally, the pipe can be heated more uniformly.

  As a more preferable aspect, the anti-freezing structure includes a plurality of the PTC heater wires connected in series, and the PTC heater wires and the piping are covered with a heat insulating member in a state where the PTC heater wires are attached to the piping. In the structure, the heat insulating member circulates the binding member on the outer wall surface of the heat insulating member along the circumferential direction of the piping at least at the positions of both ends of each PTC heater wire, and tightens the heat insulating member with the binding member Therefore, it is attached to the PTC heater wire and the pipe.

  According to this aspect, since the heat insulating member covers them with the PTC heater wire attached to the pipe, the heat from the heating element of the PTC heater wire can be efficiently transmitted to the pipe. Since the bundling member wraps around the outer wall surface of the heat insulating member and tightens the heat insulating member at least at the positions of both ends of each PTC heater wire, the heat of the heating element is prevented from escaping from the position of the end portion of the PTC heater wire. Can do. In particular, when foamed resin or foamed rubber having cushioning properties is used for the heat insulating member, even if the heat insulating member is tightened with the bundling member, it is possible to avoid damaging the heating element due to the tightening force. it can.

  As a more preferable aspect, on the premise that a plurality of PTC heater wires are connected in series, a connector for connecting the PTC heater wires in series is attached to the end of each PTC heater wire. The connector is a resin molded body formed so as to cover a connection line connected to each of the pair of power supply lines and a connection portion between the pair of power supply lines and the connection line connected thereto. The PTC heater wires are connected in series by connecting the connecting wires of connectors attached to the ends of the PTC heater wires, and the PTC heater wires connected in series are connected to each other. The connectors attached to the end portions are arranged side by side in the circumferential direction of the pipe.

  According to this aspect, since the connectors at the ends of the PTC heater wires connected in series are arranged side by side in the circumferential direction of the piping, the heating elements near the ends of the PTC heater wires connected in series are connected, It can be close to the direction of water flow in the pipe.

  In addition, since the connectors (resin moldings) of the PTC heater wires connected in series are arranged side by side in the circumferential direction of the piping, the bundling member is circulated at the position where both of the resin moldings of the connector are arranged. Then, the heat insulating member can be tightened with the binding member. Thereby, the clamping force by a binding member can be made to act on a resin molding, and it can avoid that a heat generating body etc. are damaged by the clamping force.

  Moreover, as another preferable aspect, the said piping is arrange | positioned along the horizontal direction or incline with respect to the horizontal direction, and the said PTC heater wire is attached to the outer wall surface of the lower part of the said piping. .

  According to this aspect, since the PTC heater wire is attached to the outer wall surface of the lower part of the pipe, the water in the pipe can be heated or kept warm from the lower part of the pipe. Thereby, freezing of the water in piping can be prevented more efficiently.

  Furthermore, the end of the PTC heater wire that is not connected in series with the other PTC heater wires among the PTC heater wires may be sealed by heat-sealing a power supply wire and a covering material surrounding the heating element. . Since it is not necessary to separately prepare a member for insulation sealing at the end of the PTC heater wire, the number of parts can be reduced. Further, since the sealing is performed by heat-sealing the covering material, high sealing and airtightness of the end portions are maintained for a long time.

  Further, the heating element having a positive temperature coefficient characteristic may be made of a ceramic obtained by adding an additive to barium titanate, and is made of a resin composition containing a conductive powder such as carbon black. May be. In the latter case, since the heating element has flexibility, the PTC heater wire is more flexible and flexible.

  According to this invention, piping can be heated more uniformly using a PTC heater wire.

It is a typical perspective view for demonstrating the heat-emitting part of the PTC heater wire which comprises the freezing prevention structure of 1st Embodiment of this invention. It is a typical perspective view for demonstrating the heat generating part covering body which covered the heat generating part shown in FIG. 1 with the 1st coating | covering material. It is a typical perspective view for demonstrating the PTC heater wire which covered the metal braided wire and the 2nd coating | covering material in the heat generating part covering body shown in FIG. It is a schematic diagram for demonstrating the connector for connecting PTC heater wires among the PTC heater wires shown in FIG. 1, (a) is a typical perspective view of the connector attached to the edge part of a PTC heater wire. (B) is the sectional view on the AA line of (a), (c) is sectional drawing on the BB line of (a). It is the schematic diagram which showed the edge part (tip part) of the PTC heater wire which is not connected between PTC heater lines among the PTC heater lines shown in FIG. 1, (a) is the edge part (tip part) of a PTC heater wire. (B) is sectional drawing along the longitudinal direction of (a). It is the typical perspective view showing the freeze prevention structure concerning a 1st embodiment. It is sectional drawing which cut | disconnected the antifreezing structure shown in FIG. 6 in the direction orthogonal to the water flow direction of piping. It is the typical perspective view which showed the freeze prevention structure which concerns on 2nd Embodiment, and is the typical perspective view which showed the connection part of PTC heater wires. It is typical sectional drawing which showed the freeze prevention structure which concerns on 3rd Embodiment.

Hereinafter, first to third embodiments of a freeze prevention structure according to the present invention will be described with reference to the accompanying drawings.
[First Embodiment]
1. Structure of PTC heater wire body First, the structure of the PTC heater wire will be described. FIG. 1 is a schematic perspective view for explaining a heat generating part 10 of a PTC heater wire constituting the freeze prevention structure of the first embodiment of the present invention. FIG. 2 is a schematic perspective view for explaining the heat generating portion covering 20 in which the heat generating portion 10 shown in FIG. 1 is covered with the first covering material 16. FIG. 3 is a schematic perspective view for explaining the PTC heater wire 30 in which the metal braided wire shield 21 and the second covering material 22 are covered with the heat generating portion covering 20 shown in FIG.

  The PTC heater wire 30 according to the present embodiment is an elongated flexible heater wire (see FIG. 3). As shown in FIG. 1, the PTC heater wire 30 includes a heat generating unit 10, and the heat generating unit 10 includes a first long power supply line 11 and a second long power supply line 12 that are stranded copper wires or braided wires. And a pair of feeders arranged in parallel. Between the first long power supply line 11 and the second long power supply line 12, a plurality of chip-like heating elements 13 having positive temperature coefficient characteristics are connected to these long power supply lines, and each heating element 13 are arrange | positioned in parallel at equal intervals along the longitudinal direction of these long feeders (for example, refer FIG. 2).

  The chip-like heating element 13 may be made of a ceramic obtained by adding an additive to barium titanate, or may be made of a resin composition containing a conductor powder such as carbon black. In the latter case, examples of the conductor powder include conductor powders such as carbon black and nickel. The carbon black is preferably acetylene black or furnace black having a large surface area. The conductor powder may have an average particle size of 40 to 70 μm, a larger average particle size, or a mixture with a smaller average particle size. The resin composition may be a polymer material generally used as a polymer, and examples thereof include polyethylene, polyethylene copolymer, polyester, fluororesin, fluororubber, acrylic rubber, and polyvinyl chloride.

  It is preferable that the addition amount with respect to the resin composition of conductor powder is 15-30 mass parts with respect to 100 mass parts of resin compositions. If the added amount of the conductor powder is too small, the resistance value becomes too large to generate heat. On the other hand, if the amount is too large, the resistance is lowered, and at the same time, the temperature dependence of the resistance value is lost and the PTC characteristic is not exhibited.

  The first elongate power supply line 11 and the second elongate power supply line 12 and the chip-like heating element 13 are caulked and integrated with a metal terminal 14 that mechanically and electrically connects them. The shape of the chip-shaped heating element 13 is not limited, but in this example, it is a rectangular parallelepiped having a width D, a length L, and a thickness H. As an example, the width D is 8 mm and the length L is 6 mm. , Thickness H: 1.6 mm. In order to improve flexibility, it is desirable that the value P of the width D / length L in the heating element 13 is 1 or 1 or more. As a material of the metal terminal 14, copper, phosphor bronze, iron, iron nickel alloy, gold, silver, aluminum, or the like can be used. Preferably, a conductive paste 15 is applied between the heating element 13 and the metal terminal 14.

  In addition, although the distance between adjacent chip-shaped heat generating bodies 13 and 13 may be arbitrary on condition that a required heating environment is obtained, it is the range of about 1-100 mm normally. Further, the distances between the adjacent chip-like heating elements 13 may be the same or may be arranged at different intervals.

  The heating unit 10 shown in FIG. 1 is generally wound in a roll form on a winding drum (not shown), and is drawn out from the winding drum and shown in FIG. 2 using a conventionally known extrusion molding method. Thus, the heat generating part covering body 20 in which the heat generating part 10 is covered with the first covering material 16 made of an insulating material so as to surround the heat generating part 10 can be obtained. Examples of the insulating material include thermoplastic resins such as vinyl chloride resin having electrical insulation and flexibility.

  2 may be used as a PTC heater wire, but in this embodiment, as shown in FIG. 3, for example, a metal such as a tin-plated annealed copper wire is used with respect to the entire length of the heat generating portion covering 20. A shield 21 made of braided wire is wound, and further on the second covering material 22 made of the same insulating material as that of the first covering material 16 by appropriate means (for example, using a conventionally known extrusion molding method). The PTC heater wire 30 is formed by covering.

2. 2. Structure of end of PTC heater wire 30-1. End structure where PTC heater wires 30 are connected to each other In the present embodiment, a plurality of PTC heater wires 30 shown in FIG. 3 are used by being connected in series. In order to connect the PTC heater wires 30 and 30 in series, a connector 40 shown in FIGS. 4A to 4C is attached to the end of each PTC heater wire 30.

  FIG. 4 is a schematic diagram for explaining a connector 40 for connecting the PTC heater wires 30, 30 among the PTC heater wires 30 shown in FIG. 1, and (a) shows an end of the PTC heater wire 30. The typical perspective view of the connector 40 attached to the part, (b) is the AA arrow directional cross-sectional view of (a), (c) is the BB arrow directional cross-sectional view of (a). .

  Specifically, the connector 40 includes a connection line 50, and the connection line 50 includes a first connection line 51 electrically connected to the first long power supply line 11 via the first terminal 41, and a first connection line 51. 2 and a second connection line 52 electrically connected to the long power supply line 12 via a second terminal 42. Each of the first connection line 51 and the second connection line 52 is a wiring in which copper wires 51a and 52a are covered with an insulating coating material 51b and 52b, and the first and second connection lines 51 and 52 include The resin is further coated so as to be integrated.

  Furthermore, the connection part (The part containing the 1st terminal 41 and the 2nd terminal 42) of the 1st and 2nd elongate electric power feeding lines 11 and 12 and the 1st and 2nd connection lines 51 and 52 connected to this Are covered with shrinking tubes 43, 43 so that the metal portion is not exposed.

  The shrinkable tube 43 is a tube made of a thermoplastic resin that shrinks when heated. After the connection portion described above is covered with the contraction tube 43, it is contracted by heating to seal the connection portion. The connector 40 further includes a resin molded body 44 formed of, for example, polyvinyl chloride (PVC) so as to integrally cover these connection portions.

  By providing the connector 40 with the resin molded body 44, it is possible to reinforce the connection portions between the first and second long feeders 11 and 12 and the first and second connection wires 51 and 52 connected thereto. In addition, the connection portion can be reliably prevented from being directly exposed to water or the like.

2-2. Tip structure where PTC heater wires are not connected to each other FIG. 5 is a schematic diagram showing an end (tip portion) of a PTC heater wire which is not connected to PTC heater wires among the PTC heater wires shown in FIG. (a) is a typical perspective view of the edge part (tip part) of a PTC heater wire, (b) is sectional drawing along the longitudinal direction of (a).

  As shown in FIGS. 5A and 5B, the end portion of the PTC heater wire that is not connected to the PTC heater wires (the tip portion when the power source side is the base end portion) covers the heat generating portion covering 20. 2 The heat generating part covering 20 is sealed by heat-sealing the covering 22.

  In the heat fusion, first, a suitable means, for example, a tool such as a nipper is inserted from the cut end face side, and the first long power supply line 11 and the second long power supply line extend over several millimeters from the tip. 12, the first covering material 16 covering this, and the shield 21 are removed. After that, the second covering material 22 itself corresponding to the removed portion is self-fused by thermal fusion so that the inside of the second covering material 22 is hermetically sealed. Part 23 is formed. There is no limitation on the means for heat-sealing, but self-welding with an ultrasonic welder is particularly preferable because workability and high self-fusion can be obtained.

  Thus, without using a sealing member which is a separate member, the first and second long feeder wires 11 and 12 and the heating element 13 can be sealed inside the second covering material, The number of parts can be reduced. Furthermore, by providing the sealing portion 23 by thermal fusion, high airtightness can be maintained for a long time, and the PTC heater wire 30 in which the insulation performance does not deteriorate is obtained.

3. Anti-freezing structure FIG. 6 is a schematic perspective view showing the anti-freezing structure according to the first embodiment, and FIG. 7 shows the anti-freezing structure shown in FIG. It is sectional drawing cut | disconnected by.

  As shown in FIG. 6, the freeze prevention structure 1A according to the present embodiment is a structure that prevents freezing of water flowing in a pipe 80 made of metal such as copper or resin such as vinyl chloride, and includes a plurality of PTC heaters. The wires 30, 30,... Are connected in series, and the PTC heater wire 30 and the pipe 80 are covered with a heat insulating member 60 with the PTC heater wire 30 attached to the pipe 80. The pipe 80 has a portion arranged along the horizontal direction or inclined with respect to the horizontal direction, and each PTC heater wire 30 includes a pair of long power supply lines 11 and 12 (that is, the PTC heater wire 30). It is attached to the outer wall surface of the upper part of the piping 80 so that the water of the piping 80 may flow.

  When the PTC heater wire 30 is attached to the pipe 80, the resin-made adhesive tape 61 is attached to the PTC heater wire 30 while the PTC heater wire 30 is placed on the outer wall surface of the upper portion of the pipe 80 so that the water flows. At the same time, it is wound around the pipe 80. At this time, it is preferable to wind the adhesive tape 61 so that the adhesive tape 61 does not hang over the heating element 13. Thereby, the damage of the connection part of the heat generating body 13 and the 1st and 2nd elongate electric power feeding lines 11 and 12 by the winding force of the adhesive tape 61 can be avoided.

  The PTC heater wires 30 and 30 are connected to each other by connecting the first connection wires 51 and 51 and the second connection wires 52 and 52 of the connectors 40 and 40 attached to the ends of the PTC heater wires 30 and 30. Are connected in series. The PTC heater wire 30 newly connected to the PTC heater wire 30 attached to the pipe 80 is arranged on the outer wall surface of the upper part of the pipe 80 and is attached to the pipe 80 with the adhesive tape 61 in the same operation as described above. It is done.

  The heat insulating member 60 is a cylindrical member that covers the pipe 80 to which the PTC heater wire 30 is attached. The heat insulating member 60 has a heat insulating property made of foamed resin such as foamed rubber such as closed cell nitrile synthetic rubber or urethane foam, and Made of a cushioning material. As shown in FIG. 7, the heat insulating member 60 is formed with a cut 63 along the longitudinal direction. When the heat insulating member 60 is attached to the pipe 80, the cut 63 is opened downward and the heat insulating member 60 The piping 80 is covered together with the PTC heater wire 30. Thereby, it is possible to prevent the heat of the heating element 13 from escaping from the notches 63 of the heat insulating member 60.

  In this state, the heat insulating member 60 is attached to the pipe 80 with a binding band (binding member) 72. More specifically, in this embodiment, at the positions of both ends of each PTC heater wire 30, the binding band 72 circulates on the outer wall surface of the heat insulating member 60 along the circumferential direction of the pipe 80, and the heat insulating member is formed by the binding band 72. By tightening 60, the heat insulating member 60 is attached to the pipe 80 to which the PTC heater wire 30 is attached. In this embodiment, the binding band 72 is used at the positions of both ends of each PTC heater wire 30. However, the binding band 72 may be further circulated at other positions, and the heat insulating member 60 may be tightened by the binding band 72.

  Thus, according to the freeze prevention structure 1A according to the present embodiment, the pair of long feeders 11 and 12 of the PTC heater wire 30 are attached to the outer wall surface of the pipe 80 so as to follow the direction of water flow. Therefore, the heating elements 13 of the PTC heater wires 30 are arranged at equal intervals in the direction of water flow in the pipe 80. Thereby, compared with the case where the PTC heater wire 30 is spirally wound around the pipe, the pipe 80 can be heated uniformly.

  Further, since the heat insulating member 60 covers the pipe 80 with the PTC heater wire 30 attached thereto, the heat from the heating element 13 of the PTC heater wire 30 can be efficiently transmitted to the pipe 80. Since the binding band 72 wraps around the outer wall surface of the heat insulating member 60 and tightens the heat insulating member 60 at least at both ends of each PTC heater wire 30, the heat of the heating element 13 escapes from the position of the end of the PTC heater wire 30. This can be suppressed. In particular, since foamed resin having cushioning properties or the like is used for the heat insulating member 60, even if it is tightened with the binding band 72, it is possible to avoid damage to the heating element 13 and the like due to the tightening force.

[Second Embodiment]
FIG. 8 is a schematic perspective view showing a freeze prevention structure according to the second embodiment, and is a schematic perspective view showing a connection portion between PTC heater wires. The anti-freezing structure according to the present embodiment is different from that of the first embodiment in the arrangement state of connecting portions (connectors) between the PTC heater wires. Therefore, the detailed description of the same configuration as that of the first embodiment is omitted.

  As shown in FIG. 8, in the freeze prevention structure 1 </ b> B according to the present embodiment, connectors 40, 40 attached to end portions of the PTC heater wires 30, 30 connected in series are arranged in the circumferential direction of the pipe 80. Has been placed. According to the present embodiment, the connectors 40, 40 of the PTC heater wires 30, 30 connected in series are arranged side by side in the circumferential direction of the pipe 80, so that they are connected in series as compared with the first embodiment. The heating elements near the ends of the PTC heater wires 30, 30 can be brought closer to the direction in which the water in the pipe 80 flows.

  Further, as described above, the adjacent connectors 40, 40 are arranged side by side in the circumferential direction of the pipe 80. Therefore, at the position where both the portions of the connectors 40, 40 covered with the resin molded bodies 44, 44 are arranged. The heat insulating member 60 can be tightened by the binding band 72 by rotating the heat insulating member 60 around the binding band 72. As a result, the heat insulating member 60 can be tightened at the position of the end portion of the PTC heater wire 30 using one binding band 72 and fixed to the pipe 80. Furthermore, the fastening force by the binding band 72 can be applied to the resin molded body 44, the fixing state of the PTC heater wire 30 can be stabilized by the fastening force, and damage to the heating element and the like can be avoided.

[Third Embodiment]
FIG. 9 is a schematic cross-sectional view showing the freeze prevention structure according to the third embodiment. The anti-freezing structure according to the present embodiment is different from that of the first embodiment in the position of the PTC heater wire with respect to the piping. Therefore, the detailed description of the same configuration as that of the first embodiment is omitted.

  In the freeze prevention structure 1A according to the first embodiment, the PTC heater wire 30 is attached to the outer wall surface of the upper part of the pipe 80 arranged along the horizontal direction. However, in the freeze prevention structure 1C according to the present embodiment, As shown in FIG. 9, the PTC heater wire 30 arranged along the horizontal direction is attached to the outer wall surface of the lower part of the pipe 80. The heat insulating member 60 is formed with a cut 63 along the longitudinal direction. When the heat insulating member 60 is attached to the pipe 80, the cut 63 is opened upward, and the pipe 80 together with the PTC heater wire 30 is opened by the heat insulating member 60. Cover.

  According to this embodiment, since the PTC heater wire 30 is attached to the outer wall surface of the lower part of the pipe 80, the water in the pipe 80 can be heated or kept warm from the lower part of the pipe 80. Thereby, freezing of the water in the piping 80 can be prevented more efficiently.

  The three embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and is within a range not departing from the spirit of the present invention described in the claims for utility model registration. Various design changes can be made.

  In the first to third embodiments, the PTC heater wire is attached to the pipe with the adhesive tape. However, the PTC heater wire may be attached to the pipe with a binding band, and the PTC heater wire can be attached to the pipe. In particular, the attachment method is not particularly limited. Moreover, in the 1st-3rd embodiment, although the heat insulation member was attached to piping with the binding band, you may bind a heat insulation member to piping, for example using an adhesive tape.

DESCRIPTION OF SYMBOLS 1A, 1B, 1C ... Freezing prevention structure, 10 ... Heat generating part, 11 ... 1st elongate feeder, 12 ... 2nd elongate feeder, 13 ... Heating body, 14 ... Metal terminal, 15 ... Conductive paste, 16 ... 1st covering material, 20 ... heating part covering body, 21 ... shield, 22 ... 2nd covering material, 30 ... PTC heater wire, 40 ... connector, 41 ... 1st terminal, 42 ... 2nd terminal, 43 ... contraction tube, 44 ... Resin molding, 50 ... Connection line, 51 ... First connection line, 51a ... Copper wire, 51b ... Insulation coating material, 52 ... Second connection line, 52a ... Second connection line, 52b ... Insulation coating material, 60 ... heat insulation member, 61 ... adhesive tape, 63 ... notch, 72 ... binding band, 80 ... piping

Claims (4)

A freezing prevention structure comprising at least a pipe through which water flows and a PTC heater wire attached to the pipe, and preventing freezing of water flowing into the pipe,
The PTC heater line includes a pair of power supply lines arranged in parallel, a plurality of heating elements having a positive temperature coefficient characteristic connected in parallel between the pair of power supply lines, the pair of power supply lines, A covering material made of an insulating material surrounding the heating element, and the plurality of heating elements are connected to the pair of power supply lines at equal intervals along a longitudinal direction of the pair of power supply lines. And
The anti-freezing structure, wherein the PTC heater wire is attached to an outer wall surface of the pipe so that the pair of power supply lines are along a direction in which water of the pipe flows. The anti-freezing structure is a structure in which a plurality of the PTC heater wires are connected in series, and the PTC heater wires and the piping are covered with a heat insulating member in a state where the PTC heater wires are attached to the piping,
The heat insulating member, at least at the positions of both ends of each PTC heater wire, by rotating the binding member around the outer wall surface of the heat insulating member along the circumferential direction of the pipe and tightening the heat insulating member with the binding member, The anti-freezing structure according to claim 1, wherein the anti-freezing structure is attached to a PTC heater wire and the pipe. A connector for connecting the PTC heater wires in series is attached to the end of each PTC heater wire,
The connector includes a connection line connected to each power supply line of the pair of power supply lines, a resin molded body formed to cover a connection portion between the pair of power supply lines and the connection line connected thereto, The PTC heater wires are connected in series by connecting connection wires of connectors attached to ends of the PTC heater wires,
The antifreezing structure according to claim 2, wherein the connectors attached to the end portions of the PTC heater wires connected in series are arranged side by side in the circumferential direction of the pipe.   The said piping is arrange | positioned along the horizontal direction or inclining with respect to the horizontal direction, and the said PTC heater wire is attached to the outer wall surface of the lower part of the said piping. The antifreezing structure according to any one of 3 above.

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