JPH0734393B2 - PTC heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a heating device using a positive temperature coefficient thermistor,
In particular, it relates to protection of positive temperature coefficient thermistors.

(B) Prior Art As a conventional positive temperature coefficient heating device, there is one described in Japanese Patent Publication No. 61-17351. What is described in this publication is "a combination of a corrugated and flat aluminum thin plate and an aluminum brazing sheet, or a combination of aluminum brazing meats, and these are brazed to form a heat radiator. The electrode parts provided on both sides of the positive temperature coefficient thermistor element were fixed so that they were in contact with each other.

(C) Problems to be Solved by the Invention Generally, when a certain amount of oil permeates from the surface of a positive temperature coefficient thermistor, the characteristic may change from positive to negative due to the oil content. It is known that the amount of electricity supplied to the thermistor increases, leading to short-circuit breakdown. Further, if dust or dirt is accumulated on the surface of the positive temperature coefficient thermistor at the time of this short circuit, the dust or dirt may be ignited.

Therefore, in the positive temperature coefficient heat generating device as shown in the prior art, although the heat radiation efficiency of the positive temperature coefficient thermistor is improved by the shape of the heat radiation fin, the wind resistance increases and dust, dust, oil, etc. in the air are increased. It was easy to deposit. Due to the accumulation of dust, dust, and oil, the PTC thermistor is likely to be short-circuited, and at the same time dust and dust are easily ignited.Therefore, the use conditions of the PTC device using the conventional technology are narrowly limited. It was

In order to solve such a problem, the present invention provides a positive temperature coefficient heating device which secures air permeability to the positive temperature coefficient thermistor and prevents oil from entering.

(D) Means for Solving the Problem The present invention is to mount positive radiation coefficient fins made of a conductive metal on two opposing heat generating surfaces of a positive temperature coefficient thermistor formed in a rectangular parallelepiped, and energizing between these heat radiation fins to apply the positive temperature coefficient thermistor. In a positive temperature coefficient heat generating device configured to generate heat, the end of the heat generation surface to which the heat radiation fin is attached is sealed with a silicon-based sealing material, and the sealing material is provided with a resinous cover, It is a ventilation path through the gap.

In addition, the case surrounding the positive temperature coefficient thermistor thus formed is provided with a wire net covering the heat radiation fins.

(E) Action In the positive temperature coefficient heating device configured as described above, the ends of the two opposing heat generating surfaces of the rectangular parallelepiped to which the heat radiation fins are attached are reinforced and positioned by the silicon-based sealing material, and the silicon-based sealing material is used. The gap between the sealing material and the radiation fin ensures air permeability to the PTC thermistor. In addition, the resin cover provided on the silicon-based sealing material prevents oil from entering the PTC thermistor.

Furthermore, the amount of dust and dirt adhering to the PTC thermistor is reduced by the wire mesh provided in the casing surrounding the PTC thermistor.

(F) Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a top view of a PTC thermistor with a radiation fin attached. In this figure, 1 and 2 are positive temperature coefficient thermistors (barium titanate-based semiconductor porcelain heating elements having a positive temperature coefficient of resistance) formed in a rectangular parallelepiped, and 3 and 4 are heat radiation fins, which are formed by die casting or cutting aluminum. It is formed integrally. A large number of fins are formed on one side of the heat radiation fins 3 and 4, and a mounting surface for a PTC thermistor is formed on the other side. 5
Is a radiating fin, and the mounting surface for the PTC thermistor is formed on both sides, and the fin is formed inside. Therefore, the positive temperature coefficient thermistors 1 and 2 are sandwiched by the mounting surfaces of the radiation fins 3 to 5 as shown in FIG. Reference numerals 6 to 9 denote silicon layers for joining the positive temperature coefficient thermistors 1 and 2 to the mounting surfaces of the radiation fins 3 to 5. As shown in FIG. 1, the silicon layers 6 to 9 are pressed and heat-cured to bond the positive temperature coefficient thermistors 1 and 2 to the radiation fins 3 to 5. Since the silicon layer is conductive, it does not affect the current flow to the positive temperature coefficient thermistors 1 and 2. 10 and 11 are the silicon layers coated with a thermosetting sealant (silicone sealant). It is provided at the ends of the characteristic thermistors 1 and 2 and the ends of the radiation fins 3 to 5. In addition, 12 to 14 are terminals attached to the radiation fins 3 to 5, and the conductivity with the radiation fins 3 to 5 is maintained. 15 and 16 are side caps made of resin such as PPS, which are pressed against the end portions of the positive temperature coefficient thermistors 1 and 2 and the heat radiation fins 3 to 5 so as to adhere to the silicon layers 10 and 11, respectively, and then thermally cured. It is fixed. As a thermosetting condition, 150 ° C for about 60 minutes was suitable. The side caps 15 and 16 are sectional views for the sake of explanation. Figure 2 shows the first
FIG. 7 is a side view after covering the positive temperature coefficient thermistors 1 and 2 and the heat radiation fins 3 to 5 shown in the drawing from the end (the side without the terminals 12 to 13) and covering them.

21 to 24 are thermosetting sealing materials (silicon-based sealing materials)
Then, the positive characteristic thermistors 1 and 2 are arranged on the surface where the heat radiation fins 3 and 4 are not attached, in other words, at the end of the heat generation surface to which the heat radiation fins 3 and 4 are attached.

17 to 20 are covers made of resin (PPS, etc.) and sealing materials 21
~ 24 are provided. That is, the sealing materials 21 to 24 are applied to the surface on which the heat radiation fins 3, 4, and 5 are not attached, and left for several minutes. Then, cover the sealing material 21-24 with 17-
Sealing material by heating (baking) while pressing 20
21 to 24 are hardened and the covers 17 to 20 are attached to the sealing materials 21 to 24.

Recesses are provided at the positions facing the positive temperature coefficient thermistors 1 and 2 of the covers 17 to 20 and the side caps 15 and 16 shown in FIG.

As described above, since only the ends of the heat generation surface provided with the heat radiation fins 3, 4, 5 are sealed with the silicon-based sealing materials 21-24, and the resinous covers 17-20 are provided on the sealing materials. The gap between the radiating fins 3, 4 and 5 serves as a ventilation path.

FIG. 3 is an explanatory view showing another mounting state of the portion of the cover 17 shown in FIG. The cover 17 has a minimum application amount of the sealing materials 25 and 26 so that the space 27 is formed in the recess. As a result, the air can be directly supplied to the PTC thermistor 1.

FIG. 4 is an explanatory view showing another embodiment of the cover portion.
In this figure, a positive temperature coefficient thermistor 32 is provided so as to project from the ends of the radiation fins 33, 34, and a cover 28 made of resin and having a U-shaped cross section is provided.
After fitting in the protruding part of the positive temperature coefficient thermistor 32,
This cover 28 is attached by thermosetting 0, 31. Reference numeral 29 is a space formed inside the cover 28.

As described above, the air permeability is maintained by using the silicon-based material as the sealing material. By forming a space in the resin cover, the supply of air to the PTC thermistor is further secured.

FIG. 5 is an assembly explanatory diagram of the positive temperature coefficient thermistor and the positive temperature coefficient heating device in which a metal net is attached to the heat radiation fins shown in FIGS. 1 and 2. Reference numerals 35 and 36 denote housings that are fitted together. 37 to 44 are wire mesh portions provided on the casings 35 and 36. The U-shaped housing 35 has a positive temperature coefficient thermistor, a radiation fin,
After putting things such as side caps, the housing
Insert the 36 pieces 45-47 into the holes 48-50 in the housing 35 and insert the screws 51-53.
Are screwed into the screw portions 57 to 59 of the housing 35 through the screw holes 54 to 56, respectively, to form the heat generating device. At this time, the covers 17 and 18 of the positive temperature coefficient thermistor act as spacers and the wire mesh 43 and 44
Prevents the heat radiation fins 3 to 5 from directly touching. Further, by using the metal nets 37 to 44, large dust and dirt are prevented from adhering to the radiation fins.

(G) Effect of the Invention According to the present invention, heat radiation fins made of conductive metal are attached to two heat generating surfaces of a positive temperature coefficient thermistor formed in a rectangular parallelepiped, respectively, and heat is applied to the positive temperature coefficient thermistor by energizing between these heat radiation fins. In the positive temperature coefficient heat generating device configured as above, the end of the heat generating surface of the positive temperature coefficient thermistor to which the heat radiation fins are attached is sealed with a silicon-based sealing material, and the sealing material is provided with a resinous cover, Since the gap is used as the ventilation passage, the ends of the radiation fins are reinforced with the silicon-based sealing material and the gap between the radiation fins is secured as the ventilation passage. Moreover, the silicon-based sealing material ensures air permeability to the PTC thermistor. On the other hand, since the silicon-based sealing material is used for attaching the cover, air permeability is ensured through the sealing material, and the deterioration of the performance of the positive temperature coefficient thermistor can be suppressed. Therefore, the positive temperature coefficient heating device according to the present invention can be sufficiently used even in a bad environment with a lot of dust, dust and oil.

Further, by using the wire net, it is possible to reduce the attachment of dust and dirt and to suppress the reduction of the ventilation volume.

[Brief description of drawings]

FIG. 1 is a top view of a PTC thermistor with a radiation fin attached, FIG. 2 is a side view of the PTC thermistor and the radiation fin shown in FIG. 1 seen from the end, and FIG. FIG. 4 is an explanatory view showing another mounting state of the cover portion shown in the figure, FIG. 4 is an explanatory view showing another embodiment of the cover portion, and FIG. 5 is an assembly explanatory view of the heating device according to the present invention. 1, 2 ... Positive characteristic thermistor, 3-5 ... Radiating fins, 17-20
… Cover, 21 ～ 24… Sealant, 37 ～ 44… Wire mesh.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuki Fukushima 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-60-172192 (JP, A)

Claims (2)

[Claims] 1. A positive characteristic thermistor formed in a rectangular parallelepiped is provided with heat radiating fins made of a conductive metal on two opposing heat generating surfaces, and a positive characteristic thermistor is heated by supplying electricity between these heat radiating fins. In the heat generating device, the end of the heat generating surface to which the heat radiation fins are attached is sealed with a silicon-based sealing material, and a resinous cover is provided on the heat-radiating fins to form an air passage between the heat radiation fins. Characteristic PTC device. 2. A positive characteristic thermistor formed in a rectangular parallelepiped is provided with heat dissipating fins made of conductive metal on two opposing heat generating surfaces, and a positive characteristic thermistor is heated by energizing between these heat dissipating fins. In the heat generating device, the end of the heat generating surface to which this heat radiation fin is attached is sealed with a silicon-based sealing material, and this resin sealing material is provided as a ventilation path for the heat radiation of the heat radiation fin. A positive-characteristic heat-generating device, characterized in that a case surrounding the positive-characteristic thermistor to which the fins are attached is formed, and the case is provided with a wire mesh covering the heat-radiating fins.