JPH0654293U - Submersible heater - Google Patents

Abstract

(57) [Summary] [Structure] A case having a heat dissipation plate 2, a heater 3 closely attached to the heat dissipation plate 2, and opening surfaces 1a and 1a and holes 1b for accommodating the heat dissipation plate 2 and the heater 3. 1 and 1. The heater 3 is internally provided with a heating element made of a positive temperature coefficient thermistor, has electrodes on the upper and lower surfaces of the heating element, and a pair of metal terminals electrically connected to each electrode,
A pair of lead wires electrically connected to these metal terminals are provided, and the periphery thereof is covered with an insulating case. [Effect] It has a waterproof function and can be safely installed in water. Further, the water temperature can be kept constant without separately providing a thermostat. Furthermore, the occurrence of local heating can be suppressed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an underwater heater having a PTC (Positive Temperature Coefficient) characteristic constant temperature heater, for example, a heater made of barium titanate-based porcelain semiconductor in order to maintain a constant water temperature in an aquarium for appreciating fish.

[0002]

[Prior art]

 Generally, for example, when breeding tropical fish or saltwater fish in an aquarium, in order to create an optimal environment for these fish, use a heater or the like to keep the water temperature in the aquarium constant (26 ° C to 28 ° C). Is being done. A conventional heater 21 used for this purpose is, as shown in FIG. 9, that an alumina electric insulating plate 23 around which a heating element 22 such as a nichrome wire is wound is housed in an alumina hollow tube 24. It is formed by fitting rubber caps 25, 25 into both ends of the hollow tube 24 to seal the inside and electrically insulate the heating element 22 from the outside. The lead wire 26 electrically connected to the heating element 22 is drawn out to the outside through a hole (not shown) opened in the cap 25.

The lead wire 26 of the heater 21 is electrically connected to a thermostat 29 connected to a power source, as shown in FIG. When the heater 21 is used, it is placed on, for example, gravel 28 spread on the bottom of the water tank 27, and the thermostat 29 turns the power on and off to control the heat generation temperature and keep the water temperature constant. It is like this.

[0004]

[Problems to be solved by the device]

 However, since the heat generation temperature of the conventional heater 21 is controlled by turning on / off the power by the thermostat 29, if the thermostat 29 fails, the heat generation temperature is not controlled and the water temperature is kept constant. There is a problem that it is impossible to keep it at.

Further, when the heater 21 is buried in the gravel 28, the heat generated in the heater 21 is not transferred to the water, so that the water temperature does not rise and the power is constantly turned on. Therefore, the heater 21 is locally overheated. There is a risk that it will be damaged. Further, if the heater 21 is in contact with the glass of the water tank 27 and locally overheats, the glass generated by the heater 21 may break the glass.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a highly safe underwater heater which does not cause local overheating and the like and can keep the water temperature constant at all times. Especially.

[0007]

[Means for Solving the Problems]

 In order to solve the above problems, the submersible heater of the present invention includes a radiator plate, a heater closely attached to the radiator plate, and a tubular container having an opening for accommodating the radiator plate and the heater. In addition to the above, the above-mentioned heater has a heating element composed of a positive temperature coefficient thermistor inside, has electrodes on the upper and lower surfaces of the heating element, and has a pair of metal terminals electrically connected to each electrode. It is characterized in that it has a pair of power supply lines electrically connected to these metal terminals, respectively, and the surroundings are covered with an electrically insulating and waterproof covering member.

[0008]

[Action]

 According to the above configuration, since the heater is surrounded by the electrically insulating and waterproof coating member, it is electrically insulated from the outside and has a waterproof function. Therefore, the heater can be safely installed in the water. Also, since the heating element consisting of a positive temperature coefficient thermistor has a self-temperature control function, it is necessary to separately provide a so-called thermostat such as a control circuit for keeping the heating temperature constant and a circuit for preventing overheating. Absent. Furthermore, since the heater is in close contact with the heat sink, the heat generated by the heater can be efficiently transferred to the heat sink. Further, since the heater is housed in a cylindrical container having an opening, water flows and convects through the opening. Therefore, for example, when buried in gravel or in contact with glass, the occurrence of local heating can be suppressed.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. 1 to 8.

As shown in FIG. 1, the submersible heater of the present embodiment is provided with a heat radiating plate 2 inside a case 1 as a cylindrical container having an opening in a state of partitioning a circle. A heater 3 is closely attached to the heat dissipation plate 2.

The case 1 is formed in a cylindrical shape, and both ends thereof are open surfaces 1a, 1a as openings. Therefore, the radiator plate 2 to which the heater 3 is closely attached can be inserted, and when the underwater heater is installed in the water tank, water can pass through the cylinder of the case 1. Further, a large number of holes 1b ... Are formed on the outer peripheral surface of the case 1 to facilitate water convection. Further, the case 1 is made of plastic because it plays a role of protecting the heater 3, but it may be made of metal. When the case 1 is made of metal, the case 1 itself can also function as a heat dissipation plate. Note that the case 1 does not necessarily have to be formed in a cylindrical shape for the above purpose. For example, as shown in FIGS. 2 (a) and 2 (b), if the case 1 is formed in a cylindrical shape, the case 1 has a rectangular tube shape. It is also possible to form 20.

The heat dissipation plate 2 is made of a metal plate having excellent thermal conductivity, for example, an aluminum plate, and is formed in a rectangular shape having the diameter width and the tube length of the case 1. As shown in FIGS. 3 (a) and 3 (b), the heat dissipation plate 2 is provided with through holes 2a ... At three positions in the longitudinal direction in consideration of water convection.

Further, mounting holes 2 b for mounting the heaters 3 are formed in the heat dissipation plate 2 at, for example, two positions in the longitudinal direction of the heat dissipation plate 2, so that two heaters 3 can be mounted. It has become.

As shown in FIG. 4, the heater 3 is attached to the heat radiating plate 2 with, for example, a dish 6 and a nut 7. The heat radiation plate 2 is not always limited to one as in the present embodiment, but two heat radiation plates may be provided above and below the heater 3 as shown in FIG. It is possible to make the top and bottom uniform and to improve the heat transfer efficiency.

On the other hand, as shown in FIGS. 6 and 7, the heater 3 has a heating element 4, metal terminals 8 and 8, lead wires 9 and 9 as a power supply line, and an electrically insulating and waterproof covering member. It is composed of an insulating case 10.

The heating element 4 is made of a material having a positive temperature coefficient (Positive Temperature Coefficient), for example, a ceramic semiconductor whose main raw material is barium titanate, and has a low resistance from room temperature to the Curie temperature Tc (rapid change temperature). However, it is a positive temperature coefficient thermistor as a heat sensitive element having a characteristic that the resistance value sharply increases when the Curie temperature T c is exceeded. Due to this characteristic, the heating element 4 has a self-temperature control function. The Curie temperature Tc of the heating element 4 can be arbitrarily set within the range of about 30 to 300 ° C. depending on the material composition. Therefore, for example, in order to maintain the water temperature of the aquarium for raising tropical fish, saltwater fish, etc. using the heater 3 at 26 to 28 ° C, the Curie temperature Tc may be set to 36 to 38 ° C depending on the amount of water. .

The heating element 4 has a flat cylindrical shape and, as shown in FIG. 7, has electrodes 4a and 4a formed on its upper and lower surfaces by applying, for example, silver paint.

The metal terminals 8 and 8 are in close contact with the electrodes 4 a and 4 a, respectively, and are in the form of a circular flat plate having a diameter substantially equal to the outer diameter of the heating element 4, and the inner diameter of the heating element 4 is approximately equal to the central portion. It has equal holes. In addition, power supply portions 8a and 8a for connecting the lead wires 9 and 9 are formed on the metal terminals 8 and 8 respectively. These power supply parts 8a, 8a are parallel to each other and extend in the direction of introduction of the corresponding lead wires 9, 9.

The electrical connection between the metal terminals 8 and the heating element 4 is made by attaching the electrode 4a of the heating element 4 and the metal terminal 8 with, for example, a conductive adhesive of epoxy / silver mixture. Is being done. Further, the electric connection between the power feeding portions 8a and 8a and the lead wires 9 and 9 is made by, for example, soldering the corresponding lead wires 9 and 9 to the facing surfaces of the power feeding portions 8a and 8a. .

The insulating case 10 is composed of an insulating case lower portion 10a as a covering base and an insulating case upper portion 10b. The insulating case 10 covers the heat generating element 4 and the metal terminals 8 and 8 to hermetically seal it, that is, a fixing hole 3a is formed at the center for fixing the heater 3 to the heat radiating plate 2. Has been done. A female screw groove may be formed in the fixing hole 3a if necessary. In addition, the insulating case 10 has a metal terminal 8 side end of the lead wires 9 and 9 so that a mechanical load is not applied to a soldered portion of the lead wire 9 and the power feeding portion 8a of the metal terminal 8 and a disconnection or the like does not occur. It also covers the part.

The above-mentioned insulating case 10 becomes the insulating case upper part 10b after the heating element 4 and the like are housed in the insulating case lower part 10a which is preformed by injection molding or the like and installed in the injection molding die. The insulating case lower part 10a and the insulating case upper part 10b are integrally formed by injection molding of plastics. As a result, the heating element 4 and the like are sealed and fixed inside the insulating case 10.

The insulating case 10 has a small heat shrinkage ratio, is excellent in thermal conductivity and mechanical strength, has heat resistance capable of withstanding the heat generation temperature of the heating element 4, and is water-proof that does not allow moisture such as water vapor to pass therethrough. In addition, it is necessary to have airtightness that does not allow air to pass inside and to have good adhesion to the coating material of the lead wires 9 and 9, and for example, it is formed by a polymer alloy made of nylon, polypropylene and glass. ing.

Further, the lead wires 9 and 9 connected to the metal terminal 8 are connected to a power cord (not shown), and are connected to an external power source through this power cord.

A method of manufacturing the underwater heater having the above configuration will be described.

First, in order to attach the heater 3 to the heat radiating plate 2, as shown in FIG. 4, countersunk screws 6 are inserted from the back surface 2 b of the heat radiating plate 2 into the mounting holes 2 a. Subsequently, the fixing hole 3a of the heater 3 is fitted into the screw portion 6b of the flat head screw 6 protruding from the surface 2c of the heat dissipation plate 2. After that, the flat head screw 6 is tightened with the nut 7 to bring the heater 3 and the heat sink 2 into close contact with each other. When tightening the flat head screw 6 with the nut 7, a washer, a washer, or the like may be arranged between the heater 3 and the nut 7 if necessary.

Subsequently, as shown in FIGS. 8A and 8B, the heat dissipation plate 2 to which the two heaters 3 are attached is inserted from the opening surface 1 a of the case 1, and the contact portion of the case 1 is attached. The underwater heater is completed by attaching the adhesive 11 or soldering (when the case 1 is made of metal).

As described above, in the underwater heater of the present embodiment, the heater 3 is covered with the insulating case 10 as the electrically insulating and waterproof covering member, which is made of resin, so that the heater 3 is electrically connected to the outside. It is insulated and has a waterproof function. Therefore, the heater 3 can be safely installed in water.

Further, since the heating element 4 composed of the positive temperature coefficient thermistor has the self-temperature control function, the temperature rises rapidly after energization, and when the temperature reaches a predetermined temperature, the temperature is maintained. As a result, the water temperature of the water tank rises, and it becomes possible to maintain a constant temperature. Further, this eliminates the need for separately providing a so-called thermostat such as a control circuit for keeping the heat generation temperature constant and a circuit for preventing overheating.

Furthermore, since the heater 3 is in close contact with the heat dissipation plate 2, the heat generated by the heater 3 can be efficiently transmitted to the heat dissipation plate 2, and the heat transfer area for water can be expanded. This makes it possible to further improve the heat transfer efficiency.

Further, since the heater 3 is housed in the cylindrical container having the opening surfaces 1a and 1a and the holes 1b, ..., The opening surfaces 1a and 1a and the holes 1b. Therefore, for example, when it is buried in gravel or comes into contact with glass, the occurrence of local heating can be suppressed. Further, since the heater 3 does not directly contact the glass, it is possible to avoid breaking the glass.

The attachment of the heater 3 to the heat dissipation plate 2 is not limited to screwing, and may be performed with an adhesive, for example. Therefore, in this case, the heating element 4, that is, the fixing hole 3a of the heater 3 becomes unnecessary. Further, the positions and the numbers of the fixing holes 3a formed in the heating element 4 and the heater 3 are not limited to those in the above embodiment, but can be changed depending on the size of the heater and the like. Moreover, the arrangement and number of the heaters 3 on the heat dissipation plate 2 are not limited.

Further, in the present embodiment, the opening in the case 1 is constituted by the opening surfaces 1a and 1a at both ends and the hole 1b formed in the circumferential surface, but the present invention is not limited to this. That is, for example, the flow of water can be ensured only by the opening surfaces 1a, 1a at both ends, so that the effect of the present invention is not hindered.

[0033]

[Effect of device]

 As described above, the submersible heater of the present invention includes the heat sink, the heater closely attached to the heat sink, and the cylindrical container having the opening for housing the heat sink and the heater. The above heater is internally provided with a heating element composed of a positive temperature coefficient thermistor, has electrodes on the upper and lower surfaces of the heating element, and has a pair of metal terminals electrically connected to each electrode, and these metal terminals. It has a pair of power supply lines that are electrically connected to each other, and the surroundings are covered with an electrically insulating and waterproof covering member.

Accordingly, the heater is electrically insulated from the outside and has a waterproof function, so that the heater can be safely installed in water. Further, since the heating element composed of the positive temperature coefficient thermistor has the self-temperature control function, the water temperature can be kept constant without separately providing a so-called thermostat.

Further, since the heater is in close contact with the heat sink, the heat generated by the heater can be efficiently transferred to the heat sink. Further, since the heater is housed in the cylindrical container having the opening, water flows and convects through the opening. Therefore, for example, when it is buried in gravel or comes into contact with glass, it is possible to suppress the occurrence of local heating.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an underwater heater structure according to an embodiment of the present invention.

2A and 2B show a rectangular tube-shaped case of the underwater heater, wherein FIG. 2A is a side view and FIG. 2B is a front view.

3A and 3B show how the submersible heater is attached to a heat radiating plate of a heater, wherein FIG. 3A is a plan view and FIG.
Is a front view.

FIG. 4 is a vertical cross-sectional view showing how the heater of the submersible heater is attached to a radiator plate.

FIG. 5 is a front view showing a state in which two heat radiating plates are provided above and below the heater.

FIG. 6 is a plan view showing a part of the heater of the submersible heater in a cutaway manner.

FIG. 7 is a sectional view of the heater.

FIG. 8 shows the structure of the underwater heater,
(A) is a side view and (b) is a sectional view.

FIG. 9 is an explanatory diagram showing a structure of a conventional heater.

FIG. 10 is an explanatory diagram showing a usage state of the conventional heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 case (cylindrical container) 1a opening surface (opening) 1b hole (opening) 2 heat sink 2a through hole 3 heater 4 heating element 4a electrode 7 nut 8 metal terminal 9 lead wire (feeding wire) 10 insulating case (electrical insulation) And waterproof covering member) 10a Lower part of insulating case 10b Upper part of insulating case

Claims (1)

[Scope of utility model registration request] 1. A heat radiating plate, a heater closely attached to the heat radiating plate, and a cylindrical container having an opening for accommodating the heat radiating plate and the heater, wherein the heater comprises a positive temperature coefficient thermistor. And a pair of metal terminals electrically connected to each of the electrodes, and a pair of metal terminals electrically connected to the respective metal terminals. An underwater heater having a power supply line, the periphery of which is covered with an electrically insulating and waterproof coating member.