JPH0328481Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a closed type positive temperature coefficient thermistor in which a positive coefficient thermistor element is sealed within an outer case.

(Prior Art) Generally, a closed type positive temperature coefficient thermistor is used to heat water or to heat a refrigerant in an electric refrigerator or the like.

Conventionally, as shown in FIG. 7, this type of positive temperature coefficient thermistor has a positive temperature coefficient thermistor body 3 having electrodes 1 and 2 formed on both opposing main surfaces, with lead wires 4 connected to electrodes 1 and 2, respectively. and 5 are soldered, and the PTC thermistor body 3 is placed in an exterior case (not shown) with an open end.
This exterior case is filled with a resin (not shown) with good thermal conductivity from the opening at one end,
It is generally known that a positive temperature coefficient thermistor body 3 is hermetically sealed within an exterior case.

By the way, a positive temperature coefficient thermistor is a self-contained thermistor that, in a temperature range below a predetermined temperature T ₀ determined by the material constituting the positive temperature coefficient thermistor body 3, the resistance value increases as the temperature rises, reducing or cutting off the amount of current. Although it has control characteristics, the above temperature T ₀
In a temperature range exceeding this temperature range, the self-control characteristic is lost, and if the temperature rises above this temperature, the resistance value decreases and the ability to regulate the amount of current is lost.
Therefore, if the temperature of the positive temperature coefficient thermistor exceeds T ₀ due to reasons such as overvoltage being applied,
When the temperature reaches a temperature range where the resistance value decreases, a large current flows through the PTC thermistor element 3, resulting in runaway, and the PTC thermistor element 3 is finally destroyed. In the above-described sealed PTC thermistor, when the PTC thermistor element 3 breaks down, the impact force is directly transmitted to the outer case through the resin surrounding the PTC thermistor element 3, and the resin There was also a problem in that cracks occurred in the exterior case, and water entered through the cracks in submersible heaters and the like, causing electrical leakage accidents.

Further, in the conventional PTC thermistor, the lead wires 4 and 5 are soldered directly to the electrodes 1 and 2 of the PTC thermistor body 3, so that the current supply to the PTC thermistor body 3 is turned on. , when the lead wires 4 and 5 are repeatedly turned off, the lead wires 4 and 5 may become damaged due to the difference in thermal expansion coefficient between the solder 6 that bonds the lead wires 4 and 5 to the electrodes 1 and 2, and the electrodes 1 and 2, and due to thermal deterioration of the solder. Sometimes it came off from electrode 1 or 2.

Furthermore, lead wires 4 and 5 are connected to electrodes 1 and 2.
The positive temperature coefficient thermistor element 3 soldered with
As shown in FIG. 8, the outer case 7 is open at one end.
When the resin 8 is filled into the outer case 7 through this opening, the PTC thermistor element 3 is not positioned within the outer case 7, so the PTC thermistor element 3 is tilted inside the outer case 7. The resin 8 is then filled. When such a positive temperature coefficient thermistor is tightened and fixed to a heated body (not shown), the stress of this tightening and fixing is locally concentrated on the positive temperature coefficient thermistor element 3, and the positive temperature coefficient thermistor element 3 is There was also the problem of cracks occurring.

Furthermore, in the conventional PTC thermistor, the PTC thermistor body 3 is molded with resin 8 in the outer case 7, so that the lead wires 4 and 5 may be separated by breakage of the PTC thermistor body 3. There were also problems with accidents such as short circuits occurring.

(Purpose of the invention) The present invention was devised in view of the above-mentioned problems with sealed PTC thermistors, and is designed to prevent cracks from occurring in the outer case even if the PTC thermistor body is destroyed, and It is an object of the present invention to provide a highly reliable positive temperature coefficient thermistor that does not cause cracks in the positive temperature coefficient thermistor element due to disconnection of the wire or attachment to a heated body.

(Structure of the invention) Therefore, in the present invention, a positive temperature coefficient thermistor element having electrodes formed on both opposing main surfaces is housed in an outer case, and the positive temperature coefficient thermistor element and the inner wall of the outer case A heat storage plate and a flat plate terminal are held between the positive temperature coefficient thermistor element body and another inner wall surface by the elasticity of a spring terminal housed in an elastically deformed state, and The positive temperature coefficient thermistor body is hermetically sealed within the exterior case with the lead wire conductively connected to the formed connection portion drawn out of the exterior case.

(Effects of the invention) According to the invention, the PTC thermistor element is biased almost uniformly toward one inner wall surface of the outer case by the spring force of the spring terminal and is held within the outer case. Strain applied from the outside of the outer case is absorbed by the spring terminal and space interposed between the PTC thermistor element and the outer case, preventing cracks from occurring in the outer case and preventing moisture and water from entering the outer case. Accidents caused by electrical leakage caused by intrusion can be avoided. In addition, since the lead wires are attached to the flat terminal and spring terminal to supply power to the positive temperature coefficient thermistor element, there is no possibility of the lead wire coming off like when soldering the lead wire to the electrode of the positive temperature coefficient thermistor element. It can be completely eliminated. Furthermore, according to the present invention, the positive temperature coefficient thermistor element is held in pressure contact with the inner wall surface of the outer case, so that the heat generated from the positive temperature coefficient thermistor element is almost uniformly transmitted to the outer case through the heat storage plate. , it is possible to obtain a heater with a large heat capacity and a uniform temperature distribution on the heat radiation surface of the outer case.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, a flat positive temperature coefficient thermistor element 13 having electrodes 11 and 12 formed on opposing main surfaces, respectively, is housed in an exterior case 14 with an open wound at one end. One electrode 11 of the positive temperature coefficient thermistor body 13 and this one electrode 11
One inner wall surface 14a of the exterior case 14 facing the
A heat storage plate 15 and a flat terminal 16 are interposed between the two. In addition, the above positive temperature coefficient thermistor element 1
Between the other electrode 12 of No. 3 and the inner wall surface 14b of the exterior case 14 facing this other electrode 12,
A spring terminal 17 is housed in an elastically deformed state.
The heat storage plate 15 and the flat terminal 16 are the spring terminal 1
The positive temperature coefficient thermistor element body 13 is held between the PTC thermistor element body 13 and the inner wall surface 14a of the outer case 14 with an elastic force of 7.

As shown in FIG. 2, the heat storage plate 15 is made of a material such as brass or copper that has approximately the same dimensions as the electrodes 11 of the rectangular positive temperature coefficient thermistor body 13, has good electrical conductivity, and has a large heat capacity. It is located on the electrode 11 of the positive temperature coefficient thermistor element body 13. Notches 15a, 15a are formed in the substantially central portions of both sides of the heat storage plate 15 in the longitudinal direction, and tongue pieces 13a, 16a formed on the flat terminal 16 are inserted into these notches 15a, 15a. It is inserted.

Like the heat storage plate 15, the flat terminal 16 is also made of stainless steel and has substantially the same dimensions as the electrodes 11 of the PTC thermistor body 13, and is located on the heat storage plate 15. The above flat plate terminal 16
has the center portions of its two longitudinal sides protrude outward, and the notches 15a of the heat storage plate 15,
Tongue pieces 16 each bent at a right angle toward 15a
a, 16a, and a lead wire connection portion 16b protruding in the longitudinal direction of the flat terminal 16. A lead wire 18 is soldered or spot welded to this lead wire connection portion 16b of the flat terminal 16.

On the other hand, the spring terminal 17 has its central portion curved in an arc shape on the side opposite to the electrode 12 of the PTC thermistor body 13 to form a spring portion 17a, which connects the lead wire of the flat terminal 16. It has a lead wire connection part 17b similar to the part 16b. A lead wire 19 is soldered or spot welded to this lead wire connection portion 17b.

The flat terminal 16, the heat storage plate 15, the positive temperature coefficient thermistor body 13, and the spring terminal 17 whose structure has been explained above are laminated in this order, and as shown in FIG. 3, an outer case 14 having an opening 14c at one end is formed. It is inserted into the interior through this opening 14c. Flat terminal 1
The connection portion 17 of the lead wire and the spring terminal 17 soldered or spot welded to the connection portion 16b of 6.
The lead wire 19 soldered or spot welded to the lead wire 19 is led out of the outer case 14 from the opening 14c, and a lid 21 as a closing member as shown in FIG.
is inserted until it abuts against the stepped portion 14d of the opening 14c, and is fixed with an adhesive (not shown).

The lid 21 has notches 21a and 21b into which the lead wires 18 and 19 fit, respectively.
The lid 21 also has a protrusion 21c that protrudes into the interior of the outer case 14.
As can be seen from FIG. 1, the soldered parts of the lead wires 18 and 19 are separated from each other,
This is to prevent the two from coming into contact. At the same time, the space between the positive temperature coefficient thermistor body 13 and the lid 21 is made as small as possible.

With this configuration, the positive temperature coefficient thermistor element 13 is biased almost uniformly toward the inner wall surface 14a of the outer case 14 by the spring force of the spring terminal 17, and one electrode 11 is biased toward the inner wall surface 14a of the outer case 14. 15, the heat storage plate 15 is in close contact with the flat plate terminal 16, and the flat plate terminal 16 is in close contact with the inner wall surface 14a of the outer case 14, respectively.

Therefore, the heat generated from the PTC thermistor body 13 is stored in the heat storage plate 15, and this heat is transferred to the inner wall surface 14 of the outer case 14 to which the flat terminal 16 is in close contact.
a to this exterior case 14, and the outer surface 1 of the exterior case 14 opposite to the inner wall surface 14a.
Since the heat radiation surface 4e is applied to the heated object (not shown), a heater with a large heat capacity and uniform temperature distribution on the heat radiation surface can be obtained.

In the PTC thermistor shown in FIG. 1, the external case 1
Since the strain applied to the outer case 4 is absorbed by the spring terminal 17 and the space, it is possible to prevent cracks from occurring in the outer case 14.

Further, since the lead wires 18 and 19 are not directly soldered or spot welded to the electrodes 11 and 12 of the PTC thermistor body 13, it is possible to prevent short circuit accidents due to disconnection of these lead terminals. In addition, in the above example,
Preferably, as shown in FIG. 5, a narrow fuse part 16c is formed in the connecting part 16b of the flat terminal 16 by cutting in a direction perpendicular to the direction of protrusion thereof, and the terminals are separated by this fuse part 16c. If the two parts 16b ₁ and 16b ₂ are bent so that the cross section becomes U-shaped, and the lead wire 18 is soldered or spot welded to the tip side 16b ₁ of the connecting part 16b, a positive temperature coefficient thermistor can be obtained. When a large current flows through the element body 13, the fuse portion 16c is blown, and cracks occurring in the outer case 14 due to destruction of the PTC thermistor element body 13 can be more reliably prevented. In this case, in order to protect the narrow fuse part 16c from breakage, the connecting part 16b of the flat terminal 16 is made of alumina and has a groove 22a into which the lead wire 18 is inserted, as shown in FIG. It is preferable to fit and reinforce the reinforcing member 22. This reinforcing material 22 has parts 16b ₁ , 16
b ₂ , is held by bending each tip. The reinforcing material 22 not only has the function of reinforcing the fuse portion 16c, but also prevents adverse thermal effects on the case 14 due to the fuse portion 16c being blown out by being interposed between the fuse portion 16c and the inner wall surface 14a of the case 14. It has a function that eliminates

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of the PTC thermistor according to the present invention, FIG. 2 is an exploded perspective view of parts housed in the exterior case of the PTC thermistor of FIG. Figure 1 is a partially cutaway perspective view of the exterior case of the PTC thermistor, Figure 4 is a perspective view of the lid of the exterior case in Figure 3, Figure 5 is an explanatory diagram of the fuse portion formed on the flat terminal, Figure 6 7 is a perspective view of a PTC thermistor body of a conventional PTC thermistor, and FIG. 8 is a cross-sectional view of a conventional PTC thermistor. 11, 12... Electrode, 13... Positive temperature coefficient thermistor element, 14... Exterior case, 15... Heat storage plate,
16... flat plate terminal (16a... tongue piece, 16b...
connection part), 17... spring terminal (17a... spring part,
17b... Connection portion), 18, 19... Lead wire.

Claims (1)

[Scope of utility model registration request] A flat positive temperature coefficient thermistor body with electrodes formed on both opposing main surfaces is housed in an exterior case, and one electrode of the positive temperature coefficient thermistor body and an exterior case facing this one electrode. A heat storage plate and a flat terminal are interposed between the inner wall surface of the
A spring terminal is accommodated in an elastically deformed state between the other electrode of the positive temperature coefficient thermistor element and the inner wall surface of the outer case facing the other electrode, and the heat storage plate and flat terminal are positively deformed by the elasticity of the spring terminal. The lead wires, which are sandwiched between the characteristic thermistor element, the outer case, and the inner wall surface, and are electrically conductively connected to the connection parts formed on the flat plate terminal and the spring terminal, respectively, are drawn out of the outer case. A positive temperature coefficient thermistor, characterized in that the opening is closed by a closing member and the positive temperature coefficient thermistor element body is hermetically sealed within an exterior case.