JPS60154490A - Ceramic heater - 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 (Field of Industrial Application) The present invention relates to the shape of a ceramic heater for regeneration used in, for example, a device for collecting and purifying particulates contained in the exhaust gas of a diesel engine.

(Prior art) In order to collect and purify exhaust system particulates, a heat-resistant ceramic honeycomb or foam filter is used. The idea is to burn it with a heater and regenerate the filter. In this case, the heater should be flat and U-shaped for reasons such as handling the electrodes, preventing damage to the heater, protecting the electrodes, and unifying the shape of the heater.
It is preferable to arrange a plurality of heaters formed in a character shape or a seven character shape.

Usually, a heater formed in a U-shape or V-shape is connected to a metal lead at both ends of the heater as shown in Figure 1, and is heated by electricity, so the cross-sectional area of the electrode part is The cross-sectional area of the electrode section is made considerably larger than that of the heat generating section to suppress heat generation of the electrode section. However, when attempting to arrange such a heater on the filter surface, the heat generating area is small in spite of the large space of the electrode portion, and it is therefore impossible to widely heat the surface of the filter.

(Objective of the Invention) An object of the present invention is to provide a ceramic heater that allows a fluid to be heated to flow and has high heating efficiency with low electric power.

(Example) An example of the present invention will be described in detail with reference to FIG. 2. The ceramic heater has a figure 7 shape, and the open ends are electrodes g, B, and a, respectively, and the other parts are the heat generating part 1.

The electrode portion 2.3 and the heat generating portion 1 are made of a ceramic heat generating resistor material consisting of titanium nitride and silicon nitride. The electrode part 2.3 has PT, Ni, or MO on the front and back surfaces of the terminal part 21.31.
It is constructed by fixing metals such as by paste baking or vapor deposition. The heat generating part 1 has two openings 4 on each side near the electrode parts 2 and 3. ．． 5, 6.7, and one opening 8.9 at each V-shaped tip. Due to the openings 4, 5.8 and 6° 7.9, the heating parts are 10, 11, 12, 16, 17 and 1'3.14
．． ts, :ts, 19. Further, the presence of each of the above-mentioned openings forms a gathering portion 21, 22 and a tip portion 20.

Further, the branch portions 10, 11 . Total cross-sectional area of '12 (in the direction perpendicular to the current flow; the same applies hereinafter) Σslo + 1
Similarly, the total cross-sectional area of the branch parts 13 to 1'5 is ΣSI6+17, the total cross-sectional area of the branch part 18°19 is ΣSI8+19, and the cross-sectional area S20 of the tip part 20 is ΣSIO+11+ΣS 'l 8+ 19'''S 2
The positions and sizes of the openings 4 to 9 are set so that the relationship is 0.

In this state, when a metal electrode (not shown) is fixed to the electrode part 2.3 and current is applied between the electrode part 2.3, the current flows from the electrode part 2 to the branch part 10, 11.12=collecting part 21 to branch part 16.
．． 17-Tip part 2〇-Branch part 18.19→Collecting part 22→
It flows from the branch parts 13, 14, 15 to the electrode part 3. In this case, since the collecting parts 21 and 22 do not have a closed part, their cross-sectional area is larger than that of other parts, making it difficult for them to generate heat. Therefore, the heat generation temperature is high at each of the branch portions 10 to 15, the tip, and the end portion 20. Electrode parts 2, 3. Since the cross-sectional area of the bar is larger than the cross-sectional area of each branch and tip, no heat is generated. By adopting such a structure, an effect is obtained in which the heat generating parts are scattered, making it effective as a ceramic heater for ignition having many scattered sources over a wide area.

Note that this ceramic heater was manufactured as described below. That is, the average particle size is 1. 30 wt% of TiN (titanium nitride) of um and 7 Qwt% of 5i3Na (silicon nitride) having an average particle size of 0.8 μm were mixed in a wet method, and after drying, a small amount of polyvinyl alcohol was added as a binder to obtain a molding powder. This was pressed into a heater shape using a mold press and fired at 1800° C. for 2 hours in an N2 atmosphere. 120% Ni paste was applied to the terminals of the obtained ceramic heater.
Baking was performed at 0° C. for 1 hour in an H2 atmosphere.

The overall shape of the ceramic heater that is the object of the present invention may be a U-shape or a 7-shape in plan view, or may be a modification thereof or a combination of the two, and its thickness is not limited. However, the planar shape or thickness needs to satisfy the condition that the sum of the cross-sectional areas of the branch parts other than the electrode part and the gathering part and the cross-section of the tip part are equal to each other as described above.

For example, FIG. 3 shows a U-shaped heater 60,
It branches into four sections 61, 62, 63, and 64, and the sum of the cross-sectional areas of the sections 61-64 is equal to each other as described above, and is also the same as the cross-sectional area of the tip 65. Furthermore, the branches of each section, such as branches 66, 67, 68 in section 61, are of varying length and cross-sectional area so that their respective resistances are equal. Note that the above cross-sectional area is smaller than the cross-sectional area of the gathering portion 69.70. This reduces uneven heat generation and each section 61~
64 can generate heat.

By finely branching the ceramic heater in this way, the high temperature heat generating parts can be scattered over a wide range.

Here, the shape of the openings, their number, and their installation positions are not particularly limited, but depending on the external shape of the heater, power specifications, etc., the shape may be triangular or rectangular so as to obtain uniform heat generation and uniform distribution of the branch parts. ,square.

Trapezoidal, round shapes, etc. are good.

Next, application examples of the ceramic heater of the present invention will be explained.

FIG. 4 is a front view of a heating device 23 using six ceramic heaters of the above embodiment. This device 23 is for regenerating a filter for collecting particulates in the exhaust gas of a diesel engine vehicle. In FIG. 4, the ceramic heaters 24 are installed radially such that their electrode portions are placed on the outer periphery.

Each ceramic heater 24 is fixed with a fixing screw 25 via a metal case 32. Each of the ceramic heaters 24 is connected to an electrode terminal portion 26 via a metal lead. FIG. 5 shows a sectional view taken along line AA in FIG. 4. In FIG. 5, the ceramic heater 24 is sandwiched from above and below by insulating rings 28 and 29 made of alumina sintered bodies, with a cushion material 30 intertwined with ceramic fibers and an electrode plate 31 made of nickel interposed therebetween, and further interposed between metal It is housed in a case 32. The insulating ring 28 is fixed to the case 32 using a fixing screw (25 in Fig. 4).
This is done by tightening it to the case 32.

The electrode plate 30 is connected to a nickel lead (not shown) at a portion not shown, and this lead is embedded in the insulating ring 28 and sealed at the electrode terminal portion (26 in FIG. 3).
) and is taken out to the outside and can be energized. In addition, the negative side is connected to the metal case 3 by a lead (not shown).
2 and is grounded.

FIG. 6 shows a schematic cross-sectional view of the above-mentioned heating device attached to the particulate collector.

The heating device 231 is sandwiched between an inlet 50 and an upstream part of a cylindrical particulate collection structure 49 (hereinafter referred to as a filter) housed in a casting case 43 via a sealing material 44 and cushioning materials 45 and 46. It is held in this state by flanges 47 and 48. In addition, flanges 51, 51
1 is connected to an exhaust pipe of an engine (not shown). Note that arrows 52 and 521 indicate the gas flow direction.

The reason why there are a plurality of ceramic heaters 24 is that the power consumption of the heaters 24 cannot be unnecessarily increased.

That is, in order to regenerate the filter 49 by heating the ceramic heater 24, a method is adopted in which the heaters 24 of a plurality of ceramic heaters are sequentially and intermittently energized.

For reference, the purification device of this example was installed in the exhaust gas system of an actual diesel engine (2000cc class) and tested. Further, as a comparative example, a purification device using the ceramic heater shown in FIG. 1 and having the same configuration was used, and was similarly installed in the exhaust system of a diesel engine and tested. The results are shown in the table.

The ceramic heater of the purification device of this example can burn and remove particulates over a wide range even if the heater area and power are the same as those of the comparative example. In other words, this effect is obtained because the heating source is scattered over a wide area, and in the example shown in the table, the particulate removal effect is approximately 1.8 times higher with the same electric power.

Therefore, by using this ceramic heater, it is possible to burn and remove many particulates with a small amount of electric power, and because it has a 0- or V-shape, it can be placed extremely well on a filter surface with a circular or elliptical cross section. can. Therefore, the ceramic heater of the present invention is extremely suitable for use in the floor of a heater for regenerating a filter for collecting particulates contained in automobile exhaust gas.

It goes without saying that the present invention can be used for various purposes in addition to regenerating particulate filters and heating heaters.

(Effects of the Invention) In summary, according to the present invention, the heat generating portions can be scattered at a plurality of locations, and as a result, effective heating can be performed.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a conventional example, FIG. 2 is a front view showing an embodiment of the present invention, FIG. 2(a) is a front view, and FIG.
bl is a side view, FIG. 3 is a plan view showing another embodiment of the present invention, FIG. 4 is a plan view showing an application example of the present invention, FIG. FIG. 6 is a sectional view showing a particulate collection device incorporating the heating device of FIG. 4. 1... Heat generating part, 21.31... Terminal part. Representative Patent Attorney Takashi Okabe 11th; 1 2nd [? 1 (6) (b) No. 3171 5 Fig. 4 Fig. 6 Fl

Claims (1)

[Claims] It comprises terminal parts spaced apart from each other and an arch-shaped heat generating part connected between the terminal parts, the heat generating part is made of a ceramic resistance material that generates heat when electricity is passed between the terminal parts, and the heat generating part A ceramic heater with multiple openings.