JPS59169089A - Heat generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat generating device that can be applied to an intake air heating device or a combustion device of an internal combustion engine.

Conventional heat generating devices include those that utilize a heating element such as a nichrome wire, and those that utilize a positive characteristic ceramic semiconductor (1). However, in the case of nichrome wire, there is no self-temperature control ability, and a complicated external control circuit is required to maintain a constant temperature. On the other hand, a heat generating device using a PTC ceramic semiconductor is capable of constant temperature control, but due to the characteristics of the material, the upper limit of the control temperature is at most 300°C.

The present invention provides a heat generating device that eliminates the above-mentioned drawbacks.

That is, the present invention has a honeycomb-structured substrate made of an electrically insulating ceramic material, and N having a high positive temperature coefficient as a heating resistor is provided on the surface of the lattice and through holes of this substrate.
11 films of i-based gold metal were formed.

A heat generating device with this configuration can generate up to 500
It can maintain a constant temperature at a high temperature of ~800°C and has excellent heat uniformity.

Hereinafter, the present invention will be explained in detail with reference to specific examples.
.

In FIGS. 1 and 2, reference numeral 1 denotes a substrate, which is made of, for example, cordierite material. (2) The substrate 1 has a honeycomb structure having a large number of through holes 1a as shown in the figure. 2 is a Ni-based metal thin film layer as a heater member, and this thin film layer 2 covers the lattice surface (
It is formed to a thickness of about 5 μm, for example, by electroless plating on both end surfaces of the substrate 1, the surface of the through hole 1a, and the side surfaces. The material of this thin film layer 2 is pure Ni (purity 9
(8.5% or more) containing small amounts of P (phosphorus) and B (boron) can be used. Preferably, as described later, N1-
It is B series.

Reference numeral 3 denotes thin film electrodes, which are formed on two opposing sides of the substrate 1. This electrode 3 is constructed by applying and baking Ag (silver) paste, for example.

The heating element having such a structure is assembled as shown in FIG. 3, and functions as a heating device.

That is, the heating element is attached to the terminal 4.4 made of a metal plate via a metal fitting 6 using screws 5. The electrode 3.3 of the heating element is therefore electrically connected to the terminal 4.4. These terminals 4, (3) 4 are connected to a power source 8 via a switch 7.

According to the above configuration, the Ni-based N film layer 2 generates heat by passing current between the electrodes 3 and 3. On the other hand, if a fluid such as air is blown through the through hole 1a, the air will be heated.

Of course, it is not necessary to pass fluid through the through hole 1a.

By the way, in the above embodiment, the substrate 7 of the heating element is made of cordierite that has low thermal expansion, so it can be used up to high temperatures, and it has excellent thermal shock resistance, so it can not be easily affected by temperature changes like the present heating element. Durable enough to withstand harsh conditions.

Furthermore, since the surface of cordierite is extremely porous, when the thin film layer 2 is formed on the substrate 1 made of cordierite, its mechanical adhesion strength is extremely excellent.

Furthermore, since the thin film layer 2 is formed on the lattice surface of the honeycomb substrate 1, even if a part of the thin film layer 2 peels off due to some reason, electrical passages in other areas can be ensured. It has great advantages as a heating element.

(4) Next, the experimental results will be explained. The heating elements of the two samples used in the experiment had dimensions of 35 squares x 65 nm + thickness Iotm, a through-hole mesh size of 100 mesh, and an initial resistance of 0.07Ω. The above II of one of the heating elements
The material of the film layer is Nt-P (P is 5 mol in internal mol %), and the material of the other thin film layer is N1-B (B is 2 mol in internal mol %). In addition, as another sample, a conventionally known one made of a pure NI wire wound into a coil shape was used.

The experimental results are shown in Figure 4. As is clear from FIG. 4, the Ni-B heating element has excellent heat resistance. On the other hand, conventionally known wires in which Ni wire is wound into a coil form generate local heat due to the influence of adjacent coils and are prone to wire breakage. In addition, the 'N1-P heating element melted down, but this is thought to be due to the lowering of the melting point by P. However, since it has a self-temperature control function and the control temperature is higher than that of conventionally known PTC porcelain semiconductors, N1-P type heating elements can also be used depending on the suitability of the application.

(5) Next, durability tests were conducted on the Ni-B based heating element based on its Ni-B composition ratio, and the results will be explained. The dimensions and resistance value of the sample used in the experiment were the same as those of the heating element explained in FIG. 4 above.

The durability test conditions were as follows: energization was applied for 1 minute at an applied voltage of 6 V (DC), and then energization was stopped for 5 minutes as one cycle, and this cycle was repeated for 2000 cycles.

The results are shown in Table 1.

Table 1 As understood from Table 1 above, the desirable composition range of N i-B is 1 mol % to 10 mol % of B, and the remainder (99 mol % to 90 mol %) of N(6) 1. That is, B
When Ni is included, oxidation of pure Ni is prevented and heat resistance is improved.

However, increasing the amount of B conversely deteriorates the heat generation characteristics.

The present invention is not limited to the embodiments described above, but can be modified as follows.

+l) It goes without saying that the planar shape of the through holes 1a in the honeycomb structure may be various shapes such as square, rectangle, hexagon, and triangle.

(2) The material for the substrate 1 should preferably be one with low thermal expansion, and suitable materials include cordierite, 343N4, L
i 203-AIl 203-3 i02 series, AIl
It may also be T i O3.

(3) Metal thin film 152 (7) For example, the outer surface
It can also be coated with an electrically insulating ceramic material such as g A 12204 (spinel). Such a coating layer can improve durability under a poor atmosphere.

(4) As the material for the metal thin film layer 2, it is of course possible to use a known material made by adding a rare earth element such as Y to pure Ni to improve heat resistance.

(7)

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a heating element in a heating device of the present invention;
2 is a cross-sectional view taken along line 1-1 in FIG. 1, FIG. 3 is a perspective view showing the mounting state of the heating element in the present invention, and FIG. 4 is a characteristic diagram for explaining the operation of the present invention. 1... Substrate, la... Through hole, 2... Metal thin film layer,
3... Electrode, 8... Power supply. Representative Patent Attorney Takashi Okabe (8)

Claims (1)

[Claims] +11 A substrate made of an electrically insulating ceramic material having a honeycomb structure with a large number of through holes, the lattice surface of the honeycomb structure of the substrate and the inner surface of the through holes having positive resistance temperature characteristics. A heat generating device in which a metal thin film layer of NjM is formed and the thin film layer is connected to a power source. (2) The heat generating device according to claim 1, wherein the i** layer contains 0.1 to 10 mol% of B, and the balance is Ni. (3) The heat generating device according to claim 2, wherein the substrate is made of cordierite.