JP5313597B2 - Anti-freezing heater and anti-freezing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antifreezing heater suitable for a piping system with a heater guide pipe. <P>SOLUTION: The antifreezing heater 20 comprises a heater cable 30 including a heater line inserted in a heater guide pipe 15 which is disposed along water supply and/or hot-water supply piping, a power supply line 40 which supplies power to the heater line, a sensor unit 70 including an in-pipe temperature sensor inserted with the heater line in the heater guide pipe 15, and a control box 60 where at least a switching element for turning on and off the power supplied to the heater line via the power supply line 40 and a control unit which controls the switching element based on a temperature detected by the in-pipe temperature sensor are housed. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a freeze prevention system and a freeze prevention heater for piping for water supply and / or hot water supply.

  In Patent Document 1, in a self-temperature control type heater in which two or more electrodes are embedded in close proximity to each other in a resin composition in which carbon black as a conductivity imparting agent is dispersed, the average particle diameter of carbon black is defined as carbon black. Medium particle size carbon black having a DBP absorption of 60 to 160 cc / 100 g and a large particle size carbon black having an average particle size exceeding 70 μm, and having a medium particle size carbon The mixing ratio of carbon black having a large particle size with respect to black is set to 20 to 50% by mass, and both these carbon blacks are added to 15 to 30 parts by mass with respect to 100 parts by mass of the base resin composition. It is described to provide a self-temperature controlled heater with improved output stability against fluctuations. A self-temperature control type heater having PTC characteristics is used as a water-freezing prevention heater or the like because the electrical resistance increases and the energization current value automatically decreases as the body temperature rises.

Patent Document 2 discloses a technique related to a heat insulation tube that can prevent the polybutene tube from freezing in a cold region in winter and can be easily replaced and repaired if the polybutene tube is damaged by freezing. For this reason, a flexible water sheath tube having a bellows-like uneven portion formed of a polyethylene resin material or the like is inserted into a flexible sheath tube made of a synthetic resin material, particularly a polybutene resin material, and the outside of the sheath tube is inserted. In order to prevent freezing of the flowing water pipe, a heater pipe formed of a synthetic resin material through which a self-control heater wire is inserted is positioned, and a foamed resin material such as polyurethane is provided on the outer peripheral surface of the heater pipe and the sheath pipe. It is disclosed that the heat insulating tube formed by the above method is coated.
JP 2008-123764 A Utility Model Registration No. 3084455

  Position the heater pipe formed of a synthetic resin material through a self-controlling heater wire to prevent the free flowing pipe from passing through the inside of the sheath pipe and prevent the water pipe from freezing outside the sheath pipe. A system in which the outer periphery of a pipe is covered with a heat insulating pipe is being adopted as a freeze prevention system for water pipes in areas where water supply is expected to freeze. However, in the self-temperature control type heater having PTC characteristics, the heater output tends to fluctuate with time. This is thought to be due to fluctuations in the resistance characteristics of the carbon black particles in the resin composition when the heater itself is exposed to heat fluctuations from outside and subjected to a thermal history. It has been. In general, a self-temperature control type heater having PTC characteristics is likely to be thicker and not very flexible in order to obtain a resistance value with sufficient sensitivity to temperature changes.

  For this reason, there is a demand for an anti-freeze heater suitable for being inserted into a heater tube of the anti-freeze system as described above.

  One aspect of the present invention includes a heater wire inserted into a heater guide tube provided along a pipe for water supply and / or hot water supply, a power supply line for supplying power to the heater wire, and a heater guide tube together with the heater wire And a control unit for controlling the switching element for turning on and off the power supplied to the heater line via the power supply line and the switching element based on the detected temperature of the pipe temperature sensor. An anti-freezing heater having a built-in control box.

  This anti-freezing heater is inserted into a heater guide pipe installed along a pipe for water supply and / or hot water supply together with a heater wire, and an internal temperature sensor for detecting the temperature in the heater guide pipe and a detection temperature of the internal temperature sensor And a control unit capable of turning on and off the switching element. Therefore, the output of the heater wire inserted into the heater guide tube can be controlled by the detected temperature of the temperature sensor inserted into the heater guide tube together with the heater wire without using the self-control heater wire. Therefore, a heater wire that does not require a resin layer for realizing PTC characteristics, for example, a nichrome wire, other nickel-plated copper wire, or a nickel-plated copper twisted wire covered with an appropriate coating material. It is possible to adopt a heater wire that is sufficiently high in flexibility and durability. In addition, since a thin heater wire that does not require a resin layer for realizing the PTC characteristic can be employed, a space for inserting the temperature sensor into the pipe can be secured together with the heater wire.

  For this reason, it is possible to provide an anti-freezing heater that can be more easily inserted into a heater guide pipe provided along a pipe for water supply and / or hot water supply, has durability, and can be controlled by the temperature in the heater guide pipe. . Therefore, it is possible to provide an antifreeze heater suitable for an antifreeze system having a heater guide tube.

  It is desirable that the freeze prevention heater further has an outside air temperature sensor for detecting the outside air temperature. Furthermore, the control unit turns on the switching element when the detected temperature of the outside temperature sensor is equal to or lower than the first temperature and the detected temperature of the pipe temperature sensor is equal to or lower than the second temperature, and the detected temperature of the outside temperature sensor is the third temperature. It is desirable to include a function of turning off the switching element when the temperature is equal to or higher than the temperature or the temperature detected by the in-tube temperature sensor is equal to or higher than the fourth temperature. The first to fourth temperatures are preset temperatures. The third temperature is a predetermined temperature that is equal to or higher than the first temperature, and may be the same as the first temperature. The first temperature and the third temperature are preferably in the vicinity of a temperature at which water in the pipe is expected to freeze, for example, in the range of 0 to several degrees Celsius. The fourth temperature is a predetermined temperature equal to or higher than the second temperature, and may be the same temperature as the second temperature. It is desirable that the second temperature and the fourth temperature are in a range in which water in the pipe is not expected to be frozen and an operation trouble is not caused in the system including the pipe and the heater guide pipe. It is the range of -60 degreeC, and it is still more preferable that it is the range of 20-50 degreeC.

  By providing a control unit that includes this function, this anti-freeze heater can be turned on when water in the pipe is expected to be frozen, and can be prevented when water in the pipe is not expected to be turned off. It is possible to prevent troubles in operation of the system including the inner pipe and the heater guide pipe, for example, hot water instead of water or damage to the pipe due to heat. In addition, since the power is not turned on unless the outside air temperature is equal to or lower than the first temperature or the temperature in the vicinity thereof, the power consumed for preventing freezing can be reduced, and there is no need to newly provide a temperature control for power saving. .

  The control box is an inline type box connected to the power supply line, and the outside temperature sensor is preferably built in the control box. Since the control box is connected inline with the power supply line and integrated with the anti-freeze heater, a compact and easy-to-use anti-freeze heater can be provided.

  The control box includes a first shell and a second shell combined so as to sandwich the power supply line, the switching element and the control unit are accommodated in the first shell, and the outside temperature sensor is accommodated in the second shell. It is desirable that Even in a compact box, the distance between the switching element and control unit serving as a heating element and the outside air temperature sensor can be secured, so that the outside air temperature can be detected with higher accuracy.

  The second shell includes first and second protrusions and a third protrusion sandwiched between the first and second protrusions, and an outside air temperature sensor is accommodated in the third protrusion. It is desirable that The third protrusion sandwiched between the two protrusions is less likely to be buried in the ground even when the control box is placed directly on the ground, and also provides a space for outside air to flow around the third protrusion. Cheap. Therefore, the outside air temperature can be detected with higher accuracy.

  The anti-freezing heater is preferably an in-pipe sensor line for connecting the in-pipe temperature sensor and the control unit, and has an in-pipe sensor line covered with the heater line. Since the in-pipe sensor line connecting the in-pipe temperature sensor and the control unit is covered and integrated with the heater line, the operation of inserting the heater line and the in-pipe temperature sensor into the heater guide pipe is facilitated. In addition, by fixing the in-pipe temperature sensor in a predetermined position of the heater wire in advance, the position of the in-pipe temperature sensor can be controlled only by inserting the heater wire into the heater guide tube.

  One of the different aspects of the present invention is an anti-freezing system having the above-described plurality of anti-freezing heaters and a plurality of heater guide tubes provided along each of a plurality of water supply and / or hot water supply pipes. In this anti-freezing system, the heater wires of the plurality of anti-freezing heaters and the in-pipe temperature sensors are respectively inserted into the plurality of heater guide tubes. Instead of self-control heater wires, heater wires that do not require a resin layer to achieve PTC characteristics, for example, anti-freeze heaters equipped with heater wires for resistance heating such as nichrome wires, can be used at low cost. Freezing prevention system that can be constructed can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the outline | summary of the building 1 provided with the freeze prevention system 50 of embodiment of this invention is shown. This building 1 is constructed on a fabric foundation 2, and the underfloor 4 under the floor 3 on the first floor is surrounded by the fabric foundation 2. A piping system 5 is installed under the floor 4 using a header method. The piping system 5 includes a water supply pipe 6, a water supply header 9 connected to the water supply pipe 6, a hot water supply pipe 8 from the boiler 7, and a hot water supply header 10 connected to the hot water supply pipe 8. .

  The piping system 5 further includes pipes 12a to 12e with heat insulating materials for water supply piped (arranged) from the header 9 for water supply to the devices 11a to 11e on the consumption side. Moreover, the piping system 5 includes the hot water-supplied pipes 13a to 13c for hot water supply piped (arranged) from the header 10 for hot water supply to each of the devices 11a, 11d and 11e on the consumption side.

  In this example, the consumer device 11a is a sink faucet, the device 11b is a washing machine faucet, the device 11c is a toilet, the device 11d is a toilet faucet, and the device 11e is for a bath. It is a faucet. The consumer device is not limited to these.

  FIG. 2 is a cross-sectional view (FIG. 2 (a)) and a part of FIG. 2 (b) showing the configurations of the heat-insulating pipes 12a to 12e for water supply and the heat-insulating pipes 13a to 13c for hot water supply. ). These pipes with a heat insulating material have the same configuration, and the following description will be made on behalf of the pipe 12a with a heat insulating material. The heat insulating tube 12a has a flexible flowing water guide tube 14 and a heater guide tube 15 which are provided with a bellows-like uneven portion with a polyethylene resin material or the like, and these guide tubes 14 and 15 are arranged in parallel. In this state, it is integrally covered with a heat insulating tube 16 formed of a foamed resin material such as polyurethane. A flowing water pipe 17 made of a synthetic resin material, typically a polybutene resin, is inserted into the flowing water guide pipe 14 and used as piping for water supply and / or hot water supply. A heater cable 30 of the antifreezing heater 20 is inserted into the heater guide pipe 15 in order to prevent the flowing water pipe 17 from freezing. Therefore, in the piping system 5 that employs this type of heat insulating material pipe 12a, the antifreezing heater 20 is provided along the water supply and / or hot water supply pipe 17 by inserting the heater cable 30 into the heater guide pipe 15. The heater cable 30 is laid and water can be prevented from freezing inside the pipe 17.

  FIG. 3 shows a schematic configuration of the freeze prevention heater 20. FIG. 4 shows an example in which the freeze prevention heater 20 is installed. This antifreeze heater 20 is connected to a plug 21 to be inserted into a power supply outlet 49, a power cable 22 connected to the plug 21, a control box 60 connected to the power cable 22, and a control box 60. An electric power supply cable (electric power supply line) 40 and a heater cable 30 connected to the electric power supply line 40 via a connection portion 23 are provided. A temperature sensor unit 70 is provided in the middle of the heater cable 30, and the tip of the heater cable 30 is a terminal unit 39. The heater cable 30 is inserted into the heater guide tube 15 of the heat insulating material-attached tube 12a.

  FIG. 5 shows the structure of the heater cable 30 using a cross section. The heater cable 30 includes two heater wires 33 in which a nichrome wire 31 is covered with an insulating material (insulation coating) 32, and two lead wires (sensor wires) 36 in which a copper wire 34 is covered with an insulating material 35. The two heater wires 33 and the two lead wires 36 are integrally covered with an exterior insulating coating (exterior coating) 37 and are bundled to form one heater cable 30. The inner insulating coatings 32 and 35 and the outer insulating coating 37 are made of a fluororesin such as PVDF or ETFE. The heater cable 30 has a heat resistance of about 150 ° C. The heater wire 33 is set to an output of about 5-10 W per meter (voltage AC 100 V), typically about 7 W, and a suitable one for the output of that level is selected. Therefore, instead of the nichrome wire 31, a nickel-plated copper wire, a nickel-plated copper stranded wire, or a copper alloy may be employed as a means for performing resistance heating. The two heater wires 33 and the two lead wires 36 are respectively connected (terminal processing) at the terminal portion 39 and covered with a mold resin (for example, a polypropylene resin).

  In FIG. 6, the configuration of the temperature sensor unit 70 provided in the middle of the heater cable 30 is shown through. The temperature sensor unit 70 includes a thermistor 71. The thermistor 71 is connected to one lead wire 36 exposed by removing a part of the outer sheath 37 from the two lead wires 36 included in the heater cable 30. Therefore, the control unit inside the control box 60 can detect the resistance value of the thermistor 71 or a change in the resistance value via the lead wire (sensor wire) 36, and can detect the temperature of the environment where the thermistor 71 is installed. A portion of the cable 30 from which the outer sheath 37 has been peeled is elongated by a mold resin (for example, polypropylene resin) 72 including the thermistor 71 and is formed to be slightly thick with respect to the cable 30. Unlike the thermostat, the thermistor 71 having the function of detecting the temperature without having the function of turning the power on / off depending on the temperature is compact. For this reason, in this anti-freezing heater 20, the diameter of the heater cable 30 is about 4.5 mm, whereas the diameter of the temperature sensor unit 70 is within about 7.5 mm. It can be inserted into the heater guide tube 15.

  In the temperature sensor unit 70, a thermistor 71 is connected to one of the lead wires 36 of the heater cable 30, and the lead wire 36 is used as a sensor wire for transmitting a signal of the temperature sensor (thermistor) 71 to the control box 60. The heater wire 33 of the heater cable 30 functions as a tropical region over the entire length of the heater cable 30 without being cut by the temperature sensor unit 70. The thermistor may be connected as a sensor using two lead wires. By connecting a thermistor 71 between one of the heater wires 33 and one of the lead wires 36, the heater cable 30 including the temperature sensor unit 70 can be formed using the three wires of the heater cable 30. It is.

  The heater cable 30 includes a temperature sensor unit 70 including a thermistor 71 on the way. For this reason, when the heater cable 30 is inserted into the heater guide tube 15, the sensor unit 70 is inserted into the heater guide tube 15 together with the heater wire 33. Therefore, just by inserting the heater cable 30 into the heater guide pipe 15 and installing the heater wire 33 along the flowing water pipe 17 for water supply or hot water supply, the thermistor 71 is placed in the middle of the heater guide pipe 15 as shown in FIG. It can be installed at a position suitable for measuring the temperature inside the tube.

  FIG. 7 is a cross-sectional view showing the configuration of the power supply line 40 that connects the heater cable 30 and the control box 60. The power supply line 40 is a four-wire power cord, and four conductive wires 43 in which a power line 41 such as a copper wire is covered with an insulating covering material 42 are covered with an outer covering material 44 and bundled together. . Of these four conductive wires 43, two wires are used to supply power to the heater wire 33 of the heater cable 30, and two wires store the signal of the thermistor 71 from the sensor wire 36 of the heater cable 30 in the control box 60. Used to supply the control unit. A typical power supply line 40 is of the VCTF type, and vinyl resin is used as the insulation coating materials 42 and 44. The connecting portion 23 between the power supply line 40 and the heater cable 30 is molded with polypropyne resin.

  FIG. 8 shows an expanded configuration of the control box 60. The control box 60 of the freeze prevention heater 20 is an inline type control box that is connected to the power supply line 40 and is provided so as to connect the power supply line 40 and the power cable 22. Therefore, the compact and easy-to-use anti-freezing heater 20 in which the power supply line 40, the control box 60, and the power cable 22 are connected in series like a single wiring is realized.

  The control box 60 has a long and thin box shape as a whole, and includes a first shell 61 and a second shell 62 which are divided into upper and lower parts on a central plane along the longitudinal direction. The first shell 61 and the second shell 62 are combined so as to sandwich the power supply line 40 and the power cable 22, and the inside formed by the first shell 61 and the second shell 62 is waterproofed. Form a space. In the internal space of the control box 60, a board 65 mounted with an electronic device connected to the power supply line 40 and the power cable 22 is housed. On the first shell 61 side of the substrate 65, an IC 66 on which a microcomputer as a control unit is mounted, a triac 64 as a switching element, and LEDs 67a and 67b are mounted. A thermistor 68 which is a temperature sensor for measuring the outside air temperature is mounted on the second shell 62 side of the substrate 65.

  The second shell 62 includes three protrusions 62 a to 62 c that protrude in the short direction of the control box 60. The center third protrusion 62c is hollow so as to accommodate the thermistor 68, and does not protrude from the first and second protrusions 62a and 62b on both sides. A space through which air can pass can be secured between 62b and 62b. Therefore, even if the anti-freezing heater 20 is installed so that the control box 60 is placed on the ground 4a under the floor 4, the third protrusion 62c that houses the thermistor 68 reliably comes into contact with the outside air, and the third The protrusion 62c is difficult to be buried in the ground 4a. For this reason, the outside temperature can be reliably detected with high accuracy by the thermistor 68.

  Further, in the control box 60, electronic devices such as an IC 66, a triac 64, and LEDs 67a and 67b are mounted on the first shell 61 side of the substrate 65, and a thermistor 68 is inserted into the third protrusion 62c on the opposite side. It is mounted in a state protruding from the substrate 65 (at a distance). Therefore, the thermistor 68 is arranged so as not to be affected by the heat generated by the electronic device mounted on the substrate 65. In this respect, the thermistor 68 can measure the outside air temperature with high accuracy.

  FIG. 9 is a block diagram showing the circuit configuration of the antifreezing heater 20. FIG. 10 is a flowchart showing the control of the freeze prevention heater 20. The control box 60 stores an IC 66 serving as a control unit. The IC 66 is inserted into the heater guide tube 15 together with the temperature sensor 68 for measuring the outside air temperature stored in the control box 60 and the heater cable 30. The signal with the temperature sensor 71 which measures 15 pipe | tube internal temperature is input. A triac 64 serving as a switching element is connected to the IC 66, and the IC 66 can turn on / off the supply of power to the heater wire 33 included in the heater cable 30 based on the measurement results of the temperature sensors 68 and 71.

  Further, a green LED 67a and a red LED 67b are connected to the IC 66 so that the operating state of the freeze prevention heater 20 can be displayed. The display of these LEDs 67a and 67b can be seen through the display window 69 of the control box 60 shown in FIG. In this example, when power is obtained from the plug 21, the green LED 67a is turned on. When the triac 64 is turned on, the red LED 67b is also lit. The IC 66 performs failure monitoring of heater disconnection, sensor disconnection, and sensor short circuit, and when these failures are detected, the green LED 67a blinks at intervals of 0.5 seconds.

  The control box 60 further incorporates devices such as a power supply circuit 63a for generating control power (5V), a varistor 63b for preventing high voltage generation such as lightning, and a fuse 63c.

  The IC 66, which is a control unit, switches when the detected temperature (outside temperature) T1 of the outside temperature sensor 68 is equal to or lower than the first temperature S1 and the detected temperature (inside temperature) T2 of the in-tube temperature sensor 71 is equal to or lower than the second temperature S2. The TRIAC 64, which is an element, is turned on, and the TRIAC 64 is turned on when the outside air temperature T1 is equal to or higher than the third temperature S3 equal to or higher than the first temperature S1 or the inside temperature T2 is equal to or higher than the fourth temperature S4 equal to or higher than the second temperature S2. Includes the ability to turn off. In this anti-freezing heater 20, the first temperature is 5 ° C, the second temperature is 44 ° C, the third temperature is substantially the same as the first temperature, 5 ° C, and the fourth temperature is 45 ° C. Is set.

  Therefore, as shown in FIG. 10, in step 101, when the outside air temperature T1 is not 5 ° C. or lower, if the heater is turned on in step 105 (if the triac 64 is on), the heater is turned off in step 107 ( Triac 64 is turned off). Even if the outside air temperature T1 is 5 ° C. or lower, if the tube temperature T2 is 45 ° C. or higher in step 102, the heater is similarly turned off in step 107. If the outside air temperature T1 is 5 ° C. or lower, the tube temperature T2 is 44 ° C. or lower in step 103, and the heater is turned off in step 104, the heater is turned on in step 106 (triac 64 is turned on). .

  The values of the set temperatures S1 to S4 are not limited to the above. For example, the set temperatures S1 and S3 compared with the outside air temperature T1 are preferably in the range of 0 to several degrees C. from the viewpoint of prevention of freezing. The set temperatures S2 and S4 to be compared with the in-pipe temperature T2 are ranges in which water in the pipe is not expected to freeze, and the piping system 5 with a heat insulating material including the pipe and the heater guide pipe 15 does not cause an operational trouble. It is desirable that For example, the set temperatures S2 and S4 are preferably in the range of 10 to 60 ° C, and more preferably in the range of 20 to 50 ° C.

  As described above, the anti-freezing heater 20 of this example incorporates the temperature sensor (thermistor) 68 for detecting the outside air temperature T1, and incorporates in advance a power saving function for turning on and off the heater at the outside air temperature. Therefore, a new device such as a power saving thermostat is not required to save power. Further, the freeze prevention heater 20 includes a sensor 68 for detecting the outside air temperature and a sensor 71 for detecting the temperature in the pipe. In the freeze prevention system 50 shown in FIG. 1, a plurality of freeze prevention heaters 20 are inserted into the heater guide tubes 15 of the heat insulating material-attached tubes 12 a to 12 e and 13 a to 13 c, respectively. Therefore, each antifreeze heater 20 is independently a heater based on the conditions of each of the tubes 12a to 12e and 13a to 13c with the heat insulating material, and the outside temperature and the inside temperature detected by the sensor of each antifreeze heater 20. Turn on and off. For this reason, the possibility that a plurality of heaters are simultaneously turned on in synchronization is very small, and a large inrush current will not occur unless the anti-freezing heater is turned on under special conditions. Therefore, the power supply equipment for processing an inrush current becomes unnecessary.

  Further, instead of a contact control device such as a thermostat, the temperature is detected by the thermistors 68 and 71, the triac 64 is adopted as a switching device, and a non-contact control circuit and a microcomputer control are adopted. Therefore, the antifreezing heater 20 having high reliability and durability can be provided.

  Therefore, the freeze prevention heater 20 can efficiently save power consumption only in the winter period. For this reason, it is effective not only for a heat insulating material pipe adopting a cross-linked polyethylene pipe but also for a conventional water pipe freezing prevention using a metal pipe or the like. In the anti-freezing system 50 shown in FIG. A heater 20 is also installed in the water pipe 6, the water supply header 9, the hot water supply pipe 8 from the boiler 7, the hot water supply header 10, and the like. In these tubes, the antifreeze heater 20 is disposed along the tube and the outside thereof is covered with a heat insulating material.

  Furthermore, this anti-freezing heater 20 employs a fluororesin for the outer sheath of the heater cable 30 inserted into the heater guide tube 15, and has high heat resistance (150 ° C.), cold resistance (flexibility at low temperature), High electrical insulation and further flame retardancy are obtained. Therefore, it is possible to provide an anti-freezing heater having high safety and durability and having a long life.

  Further, the heater cable 30 covered with the fluororesin is excellent in self-lubricating property with low friction and is easy to be inserted into the heater guide tube 15. In addition, a small device such as a thermistor is used instead of a large device such as a thermostat to detect the temperature, and the thermistor 71 that detects the temperature in the tube is integrated with the heater cable 30, so that the heater guide tube The installation of 15 internal sensors is also easy. Therefore, it is possible to provide an anti-freezing heater that can be easily applied to a tube with a heat insulating material.

  Further, by inserting a thermistor 71 for detecting the temperature inside the tube into the heater guide tube 15 together with the heater wire 33, it is strong against bending and pulling instead of a self-temperature control type heater that is weak against bending and pulling. A heater wire such as a nichrome wire is used to control the temperature based on the temperature inside the tube. Also, in contrast to self-temperature-controlled heaters that can be expected to deteriorate over time due to changes in resistance value, heater wires such as nichrome wire basically have no resistance change, have a long life, and are stable over a long period of time. Demonstrate ability as a heating element. Therefore, in this respect as well, it is possible to provide a freeze-proof heater having high safety and durability and having a long life.

  In addition, this invention is not limited to the antifreezing heater illustrated above. For example, the control box is not limited to the in-line type arranged in series with the cord, and various modifications such as an integral type with a plug are possible. In addition, one control box can be provided in common for a plurality of heater cables, and a switching element can be arranged for each heater cable and individually controlled. The heater wire is not limited to the nichrome wire, and may be a copper wire with a large amount of copper component. The heating value of the heater wire is not about 7 W per meter, and may be high or low. In addition, a self-temperature control type heater can be used as the heater, and power consumption can be further reduced by changing the heater output in a variable manner according to the temperature in the pipe.

  Although a thermistor whose resistance value varies is employed as the temperature sensor, other types of temperature sensors such as thermocouples may be used. Further, a plurality of temperature sensors connected in series or in parallel may be inserted into the heater guide tube. It is also possible to provide a heater cable with a plurality of temperature sensors. It is also possible to insert a sensor for detecting the temperature in the tube into the heater guide tube separately from the heater wire. However, as described above, it is possible to significantly ease the construction work by integrating the heater cable.

The figure which shows the outline | summary of the building provided with the freeze prevention system. The figure which shows schematic structure of piping with the heat insulating material for water supply and / or hot water supply provided with the freeze prevention system. The figure which shows the external appearance of a freeze prevention heater. Sectional drawing which shows the state which inserted the freeze prevention heater in the heater guide pipe | tube of piping with a heat insulating material intermittently. The figure which expands and shows the VV cross section of the freeze prevention heater of FIG. The figure which expands and shows the sensor part of the freeze prevention heater of FIG. The figure which expands and shows the VII-VII cross section of the antifreezing heater of FIG. The figure which expand | deploys and shows schematic structure of the control box of the freeze prevention heater of FIG. FIG. 4 is a circuit diagram of the freeze prevention heater of FIG. 3. The flowchart which shows operation | movement of the antifreezing heater of FIG.

Explanation of symbols

20 Antifreeze heater, 30 Heater cable 33 Heater wire, 36 Lead wire (sensor wire)
40 Power supply line 60 Control box 68, 71 Temperature sensor (thermistor), 70 Sensor section

Claims (7)

A heater wire inserted into a heater guide pipe provided along a pipe for water supply and / or hot water supply;
A power supply line for supplying power to the heater wire;
A temperature sensor in the tube inserted into the heater guide tube together with the heater wire;
A control box including at least a switching element for turning on and off power supplied to the heater line via the power supply line and a control unit for controlling the switching element based on a temperature detected by the in-pipe temperature sensor; Having an anti-freeze heater. In Claim 1, it further has an outside temperature sensor for detecting outside temperature,
The control unit turns on the switching element when the detected temperature of the outside temperature sensor is equal to or lower than a first temperature and the detected temperature of the pipe temperature sensor is equal to or lower than a second temperature, and the detected temperature of the outside temperature sensor is An anti-freezing heater comprising a function of turning off the switching element when the temperature is not less than a third temperature not less than the first temperature or the temperature detected by the in-pipe temperature sensor is not less than a fourth temperature not less than the second temperature.   The anti-freezing heater according to claim 2, wherein the control box is an in-line type box connected to the power supply line, and the outside air temperature sensor is built in the control box. The control box according to claim 3, comprising a first shell and a second shell combined so as to sandwich the power supply line.
An anti-freezing heater in which the switching element and the control unit are housed in the first shell, and the outside air temperature sensor is housed in the second shell.   5. The fourth shell according to claim 4, wherein the second shell includes first and second protrusions, and a third protrusion sandwiched between the first and second protrusions. An anti-freezing heater in which the outside temperature sensor is housed in a part.   6. The antifreeze heater according to claim 1, comprising an in-pipe sensor line for connecting the in-pipe temperature sensor and the control unit, the pipe being covered with the heater line. A plurality of antifreeze heaters according to any one of claims 1 to 6;
A freeze prevention system having a plurality of heater guide tubes provided along each of a plurality of water supply and / or hot water supply pipes,
The anti-freezing system, wherein the heater wires of the plurality of anti-freezing heaters and the in-pipe temperature sensors are respectively inserted into the plurality of heater guide tubes.

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