JPH0629078A - Heater - Google Patents

Abstract

(57) [Summary] [Structure] Heating element 2, electrodes 2a, 2a provided on the upper and lower surfaces of heating element 2, metal terminals 3.3 connected to electrodes 2a, 2a, and metal terminals 3.3. Covering the exposed portions of the heating element 4, the electrodes 2a and 2a, and the metal terminals 3 and 3 and the connection portions of the lead wires 4 and 4 to the metal terminals 3. And an insulating case 5 electrically insulating from the outside. [Effect] The lead wire 4.4 is provided on the outer surface side of the metal terminal 3.3.
The insulating case 5 has a metal terminal
・ The outer surface of 3 can be thinly formed. Therefore, the main heater 1 can be made thin, and when the main heater 1 is attached to an object to be heated, the heat generated by the heating element 2 can be efficiently conducted to the object to be heated.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a PTC (Positive Tem)
The present invention relates to a heater that is made of, for example, a barium titanate-based porcelain semiconductor having a perature coefficient and can be used in many fields as a constant temperature heater or a local heating heater.

[0002]

2. Description of the Related Art Heretofore, there has been known a heater comprising a barium titanate-based porcelain semiconductor which is a positive temperature coefficient thermistor and having a plate-shaped heating element having a self-temperature control function.
This heater does not require a control circuit for keeping the heat generation temperature constant and a circuit for preventing overheating, and has extremely high safety.

As a heater of this type, Jitsuko Sho 47-26
In Japanese Patent Laid-Open No. 226, electrodes are provided on the upper and lower surfaces of a plate-shaped heating element made of a positive temperature coefficient thermistor, terminal plates are provided on the outer surfaces of both electrodes, and a heat dissipation plate is provided on the outer surface of one of the terminal plates. A structure in which an insulating plate is provided on the outer surface of the other terminal plate is disclosed. Further, in Japanese Utility Model Laid-Open No. 58-53498, electrodes are provided on both upper and lower surfaces of a plate-shaped heating element composed of a positive temperature coefficient thermistor.
That is, a structure in which terminal plates are provided and an insulating plate is provided on the outer surfaces of both of these terminal plates is disclosed. In both of the above heaters, a lead wire as a power supply wire is connected to the terminal plate by, for example, soldering, and the lead wire is connected to a power source to supply power to the heating element.

However, the above-mentioned structure has a problem that the insulating structure is insufficient and the safety is lowered particularly when it is used in a humid place.

On the other hand, as a means for solving such a problem, Japanese Utility Model Publication No. 3-9283 discloses that a plate-shaped heating element made of a positive temperature coefficient thermistor is provided with electrodes on both upper and lower sides.
A structure is disclosed in which lead wires are soldered to the outer surfaces of these electrodes, and the heating element, both electrodes, and the connection portions of the lead wires with the electrodes are covered with a heat conductive insulating resin such as a silicone resin. There is.

[0006]

However, in the structure of Japanese Utility Model Publication No. 3-9283 mentioned above, although a good insulation state is obtained, the lead wires are soldered to the outer surfaces of both electrodes. The coating with the heat conductive insulating resin must be thick enough to absorb the protrusions on the electrode surface caused by soldering the lead wires. As a result, the resin layer becomes thick, the heater becomes thicker and larger, and the heat generated by the heating element cannot be efficiently conducted to the object to be heated.

Therefore, the present invention can be made thin.
Moreover, it is an object of the present invention to provide a heater that can efficiently transfer the heat generated by the heating element to the object to be heated.

[0008]

In order to solve the above-mentioned problems, the heater of the present invention is a heater in which electrodes are provided on the upper surface and the lower surface of a heating element composed of a positive temperature coefficient thermistor. A pair of electrically connected flat plate-shaped metal terminals, a pair of power supply lines electrically connected to the facing surfaces of these metal terminals, and the exposed portions of the heating element, the electrodes and the metal terminals and the power supply lines. It is characterized in that it is composed of an electrically insulating coating member that covers the connection portion of the electric wire with the metal terminal and electrically insulates it from the outside.

[0009]

According to the above construction, since the pair of power supply lines for supplying power to the heating element are connected to the facing surfaces of the metal terminals, the protrusion of the connection portion when this connection is made by soldering, for example. The portion is formed on the opposite surface side of the metal terminal and is not formed on the outer surface side of the metal terminal. Therefore, the electrically insulating covering member does not need to be formed thick on the outer surface side of the metal terminal in order to absorb the above convex portion, and can be formed thin. As a result, the present heater can be made thin, and when the present heater is attached to an object to be heated, the heat generated by the heating element can be efficiently conducted to the object to be heated. That is, the object to be heated can be efficiently heated.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

As shown in FIGS. 1 and 2, the heater 1 according to the present embodiment comprises a flat cylindrical heating element 2, metal terminals 3 and 3, lead wires 4 and 4 as a power supply wire, and electrical insulation. It is composed of an insulating case 5 as a covering member.

The above heating element 2 has a positive temperature coefficient (Positive).
Barium titanate-based ceramic semiconductor barium titanate based on barium titanate, which has a low temperature coefficient and is doped with a small amount of an oxide of a rare earth element such as La or Y or an oxide such as Nb or Bi. It is formed by a positive temperature coefficient thermistor made of a ceramic semiconductor as a main raw material. This positive temperature coefficient thermistor has a low resistance from room temperature to the Curie temperature Tc (rapid change temperature), but has a characteristic that the resistance value sharply increases when the Curie temperature Tc is exceeded. Due to this characteristic, the heating element 2
When a voltage is applied, the resistance value is small at first because of the low temperature, a large current flows, and the power consumption is large, so the temperature rises rapidly. Then, when the temperature exceeds the Curie temperature Tc, the resistance value sharply increases, so that the power consumption is significantly reduced. As a result, the temperature of the heating element 2 does not rise above a certain temperature, and the certain temperature is kept stable, thus exhibiting a self-temperature control function. The Curie temperature Tc of the heating element 2 can be arbitrarily set within the range of about 30 to 270 ° C. by adjusting the material composition. For example,
If a part of barium of barium titanate is replaced with Pb, the Curie temperature Tc can be increased from the normal value of about 120 ° C. Further, if a part of barium is replaced with Sr, the Curie temperature Tc can be lowered. Therefore, the Curie temperature Tc may be set in consideration of the condition of using the heater 1, safety and power saving.

As shown in FIG. 3 (a), the heating element 2 is formed into a flat cylindrical shape. The upper surface and the lower surface of the heating element 2 are coated with, for example, silver paint so that the electrodes 2a.
2a is provided. In addition, in the central portion of the heating element 2,
A positioning hole 2b penetrating the upper and lower surfaces is formed.

As shown in FIGS. 3 (b) and 3 (c), the metal terminal 3 is formed in a flat plate shape substantially equal to the outer diameter of the heating element 2 and has a positioning hole 2b for the heating element 2 at the center thereof. It has a positioning hole 3b having a diameter substantially equal to that of the hole. Also, the metal terminal 3
A power feeding portion 3a for connecting the lead wire 4 is formed on the. These power feeding portions 3a, 3a are parallel to each other and are displaced from each other in the facing direction, and extend in the introduction direction of the corresponding lead wires 4, 4.

The metal terminal 3 and the heating element 2 are electrically connected to each other by connecting the electrode 2a provided on the heating element 2 and the metal terminal 3 to each other.
For example, it is carried out by bonding with an epoxy / silver mixed conductive adhesive (for example, DEMETRON 6290-0343 manufactured by Degussa). Further, the lead wires 4 are connected to the power feeding portions 3a, 3a by soldering or the like on the facing surfaces of the power feeding portions 3a, 3a. In this case, the power feeding unit 3a
Due to the positional relationship of 3a, one lead wire 4 is connected to one metal terminal 3 at the first position, the other lead wire 4 is connected to the other metal terminal 3 at the second position, and the first position is , Is arranged on one side of a plane perpendicular to the electrode 2a, and the second position is arranged on the other side of the plane. As a result, the lead wires 4 and 4 do not hinder the further thinning of the heating element 2. The lead wires 4 and 4 are parallel to the mounting surface of the insulating case 5 on the object to be heated, and the distances to the mounting surface are the same.
Is derived from. Then, the heating element 2, the metal terminals 3 and 3 and the lead wires 4 and 4 constitute the heating unit 8 shown in FIG.

The insulating case 5 is made of, for example, an electrically insulating thermoplastic such as 6-nylon, and is composed of an insulating case lower portion 6 and an insulating case upper portion 7 as shown in FIG. The insulating case 5 is formed so as to cover and seal the heat generating unit 8, and a fixing hole 1a used when the heater 1 is screwed to the object to be heated is provided in the central portion. The insulating case 5 has a pre-molded insulating case lower part 6 in which the heating element 2 and the like are housed, and after being installed in an injection molding die, an insulating case upper part 7 is made of plastic as an electrically insulating material. The insulating case lower part 6 and the insulating case upper part 7 are integrally formed by injection molding. As a result, the heat generating unit 8 excluding the open end side portions of the lead wires 4 is sealed and fixed inside the insulating case 5.

Fixing hole 1 in lower part 6 of the insulating case
The portion corresponding to the peripheral portion of a is a positioning hole 2 for the heating element 2 when the heating unit 8 is arranged on the lower portion 6 of the insulating case.
b and the positioning holes 3b and 3b of the metal terminals 3.3, which are positioning protrusions 6a for positioning the heat generating unit 8.

The lead wires 4 and 4 are connected to the power feeding portions 3a and 3a.
Since there is no protrusion on the outer surface of the metal terminals 3 and 3 connected to the opposing surface of a, the insulating case 5 is located on the outer surface of the metal terminals 3 and 3, that is, to be heated. The part to be attached to the object is thinly formed.

Further, as described above, the insulating case 5 is connected to the power feeding portion 3a so that the soldering portion of the lead wire 4 and the power feeding portion 3a of the metal terminal 3 is not subjected to a mechanical load and is not broken. Metal terminal 3 of lead wire 4 including connection part
It also covers the side ends. The insulating case 5 has a small heat shrinkage, is excellent in thermal conductivity and mechanical strength, is heat resistant to withstand the heat generation temperature of the heat generating element 2, is waterproof so as not to pass moisture such as water and water vapor therein, and It is necessary to have airtightness that prevents air from passing inside and to have good adhesion to the coating material of the lead wires 4 and 4. Therefore, the insulating case 5 is made of nylon, for example.
It is also formed by a polymer alloy made of polypropylene and glass fiber. The insulating case 5 can also be made of thermosetting plastics.

Further, if the insulating case lower part 6 and the insulating case upper part 7 are made of the same or the same electric insulating material, the mutual affinity is good and the thermal expansion coefficients are equal, so that they are integrated. Then it is desirable. However, from the viewpoint of heat conduction, it is preferable that the insulating case lower part 6 satisfactorily conducts heat to the object to be heated, while the insulating case upper part 7 is difficult to dissipate heat into the air. Therefore, when the latter point of view is prioritized, the insulating case lower portion 6 is made of a material having both good thermal conductivity and good electrical insulation, for example, the above-mentioned polymer alloy, while considering mutual affinity and thermal expansion coefficient. It is preferable to use a material having relatively low thermal conductivity, such as an epoxy resin, for the upper part 7 of the insulating case.

Next, a method of manufacturing the heater 1 having the above structure will be described with reference to FIGS.

First, as shown in FIG. 3A, a flat cylindrical heating element 2 is prepared and fired. Next, the silver coating is applied to the upper surface and the lower surface of the heating element 2 and fired to form the electrode 2
a.2a is formed.

Next, as shown in FIG.
The metal terminals 3 and 3 are attached to the electrodes 2a and 2a by a conductive adhesive, and the lead wires 4 are soldered to the facing surfaces of the metal terminals 3 and 3a and 3a, respectively. Alternatively, the lead wires 4 may be soldered to the facing surfaces of the power feeding portions 3a and 3a, respectively, and then the metal terminals 3 and 3 may be attached to the electrodes 2a and 2a with a conductive adhesive. In this way, the heat generating unit 8 as shown in FIG.

Next, as shown in FIG. 4, the heat generating unit 8 is placed on the lower portion 6 of the insulating case which has been preformed by injection molding or the like. At this time, the heat generating unit 8 is arranged so that the positioning convex portion 6a of the insulating case lower portion 6 is fitted into the positioning hole 2b of the heating element 2 and the positioning holes 3b and 3b of the metal terminals 3.3.

After that, the insulating case lower portion 6 is placed in an injection molding die, and the insulating case upper portion 7 is formed by injection-molding plastics to be the insulating case upper portion 7 to insulate the insulating case lower portion 6 from the insulating case lower portion 6. An insulating case 5 is formed which is integrated with the case upper portion 7. As a result, the heat generating unit 4 is covered with the insulating case 5 with no gap except the open end side portions of the lead wires 4 and 4 to be hermetically sealed and insulated from the outside.

As described above, the heater 1 as shown in FIGS. 1 and 2 can be obtained. In addition, lead wire 4
A plug or the like may be attached to the tip of 4 to facilitate connection with an external power source, for example. Moreover, you may provide a female screw groove in the fixing hole 1a as needed.

As described above, in the heater 1 of this embodiment,
Since the lead wires 4 and 4 are connected to the opposing surfaces of the power supply portions 3a and 3a of the metal terminals 3 and 3, respectively.
The convex portion due to the connection of 4 does not occur on the outer surface side of the metal terminals 3 and 3. Therefore, the insulating case 5 need not be formed thick on the outer surface side of the metal terminals 3 to absorb the above-mentioned convex portions, and can be formed thin. This allows
The heater 1 can be made thin, and the heater 1
When the is attached to the object to be heated, the heat generated by the heating element 2 can be efficiently conducted to the object to be heated.

Further, since the fixing hole 1a for screwing is provided in the central portion of the heater 1, it is possible to screw the heater 1 to the object to be heated by inserting a screw into the fixing hole 1a, for example. Has become. As a result, the upper surface or the lower surface of the heater 1 can be brought into close contact with the object to be heated, which also allows the heat generated by the heating element 2 to be efficiently conducted to the object to be heated.

Further, since the flat metal terminal 3 is used, the insulating case 5 can be thinned by this, and the heat transmission efficiency can be further improved.

Further, in the present heater 1, the heating unit 8 including the heating element 2 and the like is covered with the insulating case 5 and electrically insulated from the object to be heated. Therefore, the heater 1 can be attached in close contact with an object to be heated such as metal. Further, since the insulating case 5 is waterproof, the heater 1
Can also be used to heat and keep warm liquids such as water and milk. Furthermore, if the insulating case 5 is made of, for example, a silicone resin, it is possible to impart flame retardancy to the heater 1.

In the above embodiment, the case where one heating element 2 is used for the heater 1 has been described as an example, but the number of heating elements 2 used is not limited to one. It may be two or more. The shape of the heater 1 is not limited to the cylindrical shape described above, and may be various shapes such as a square plate shape. Further, the shape of the heating element 2 is not limited to the flat cylindrical shape described above, and may be, for example, a disk shape or a rectangular parallelepiped shape. Further, the positions and the numbers of the fixing holes 1a formed in the heating element 2 and the heater 1 are not limited to those in the above embodiment, but may be changed depending on the size of the heater or the method of attaching to the object to be heated. It is possible.

In addition, in this embodiment, the electrode 2a of the heating element 2 is used.
The case where the connection between the metal terminal 3 and the metal terminal 3 is made with the conductive adhesive as described above is shown. However, although the method using the conductive adhesive is simple and excellent, it takes about one day to cure the conductive adhesive, and the conductive adhesive drips onto the side surface of the heating element 2 and both sides. The mass production efficiency of the heater 1 is restricted by the consideration that the electrodes 2a and 2a are not short-circuited.

Therefore, in order to further improve the mass production efficiency of the heater 1, as shown in FIG. 5 (a), the electrodes 2a, 2a of the heating element 2 and the metal terminals 3,
It is good to cover 3 with a cap 9. The cap 9 is made of the same electrically insulating material as the insulating case 5. Figure 5
As shown in (b), a positioning hole 9a is formed in the center of the upper surface of the cap 9, and a window 9b is formed on the side surface thereof to allow the feeding portions 3a, 3a to project. The diameter of the positioning hole 9a is substantially equal to the outer diameter of the positioning protrusion 6a in the lower portion 6 of the insulating case, and the width of the window 9b is equal to the width of the power feeding portion 3.
The height of the window 9b corresponds to the total of the thickness of the heating element 2 and the thickness of the single metal terminal 3 corresponding to the horizontal distance of a · 3a.

Here, an example of specific design values relating to the size of the heater 1 will be shown. The bottom wall of the insulating case lower part 6, the metal terminal 3, the heating element 2, the upper wall of the cap 9 and the upper wall of the insulating case upper part 7 have thicknesses of 1.0 mm and 0.2 m, respectively.
m, 2.5 mm, 0.5 mm and 0.5 mm, and the thickness of the heater 1 is 4.9 mm after all. Since the cap 9 is not used when the electrode 2a and the metal terminal 3 are attached with a conductive adhesive, the thickness of the upper wall of the insulating case upper part 7 is 1.0 m.
Set to m. The outer diameter of the heating element 2 is, for example, 15 m.
m.

Next, in order to manufacture the heater 1 using the cap 9, first, the lower metal terminal 3, the heating element 2 having the electrodes 2a and 2a formed thereon, and the upper metal terminal 3 are arranged in this order in the lower part of the insulating case. Fit in 6. Then, in the next soldering step, the lead wires 4 are soldered to the facing surfaces of the power feeding portions 3a, 3a, respectively. The time when the soldering process of the lead wire 4 is performed is not limited to this, and before the metal terminals 3 and 3 are fitted into the insulating case lower part 6, or each metal terminal 3 and 3 is fitted into the insulating case lower part 6. However, it may be at each point in time. After this, the positioning hole 9a of the cap 9
The heating unit 8 is obtained by covering with the cap 9 so that the positions of the window 9b and the window 9b match the positions of the positioning protrusion 6a and the power feeding portions 3a. Next, injection molding for providing the insulating case upper portion 7 is performed.

As described above, if the heating unit 8 is assembled by using the cap 9 instead of the conductive adhesive, the curing time of the conductive adhesive can be saved, and the electrodes 2a, 2a due to the dripping of the conductive adhesive can be removed. No more worrying about short circuits. As a result, if the cap 9 is prepared in advance, the mass production efficiency of the heater 1 is improved.

[0037]

As described above, the heater of the present invention has a pair of flat metal terminals electrically connected to the electrodes provided on the upper and lower surfaces of the heating element, respectively, and the opposing surface sides of these metal terminals. A pair of power supply lines electrically connected to the
It is configured by an electrically insulating coating member that covers the exposed portion of the heating element, the electrode, and the metal terminal and the connection portion of the power supply line with the metal terminal to electrically insulate from the outside.

As a result, no protrusions are formed on the outer surface of the metal terminal for connecting the power supply line, for example, by soldering, and the electrically insulating coating member can be thinly formed on the outer surface of the metal terminal. Therefore, the present heater can be made thin, and when the present heater is attached to an object to be heated, the heat generated by the heating element can be efficiently conducted to the object to be heated. Can be efficiently heated.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a heater according to an embodiment of the present invention.

FIG. 2 is a schematic front view showing the heater partially broken.

FIG. 3A is a view showing a manufacturing process of the above heater,
FIG. 3B is a perspective view showing a step of forming electrodes on the heating element, FIG. 2B is a perspective view showing a step of connecting lead wires to the metal terminals and a step of attaching the metal terminals to the electrodes, and FIG. It is a perspective view which shows the heat generating unit obtained through the process of the same figure (b).

FIG. 4 is a vertical cross-sectional view showing a state in which the heat generating unit is arranged on the lower part of the insulating case in the injection molding process of the upper part of the insulating case in manufacturing the heater.

5A is a sectional view showing another structural example of the heater, and FIG. 5B is a perspective view showing a cap used in the heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 heater 2 heating element 2a electrode 3 metal terminal 3a power supply section 4 lead wire (power supply line) 5 insulating case (electrically insulating covering member) 6 lower insulating case 7 upper insulating case 8 heating unit

Claims (1)

[Claims] 1. A heater in which electrodes are provided on an upper surface and a lower surface of a heating element composed of a positive temperature coefficient thermistor, and a pair of flat metal terminals electrically connected to the electrodes, respectively, and a pair of metal terminals of the metal terminals. A pair of power supply lines electrically connected to the facing surface side and the exposed portions of the heating element, the electrode and the metal terminal and the connection part of the power supply line with the metal terminal are covered to electrically insulate the outside. And an electrically insulating coating member.