JPS62182418A - Ceramic heating device - Google Patents

Abstract

PURPOSE:To prevent any crack in a ceramic heater due to oxidation of a bonding material from occurring, by attaching a holding electrode to a tip of the electrode inserted into a through hole of ceramic heater, and installing a bank part for the bonding material between the holding electrode and the electrode. CONSTITUTION:A through hole 12 is installed in a ceramic heater 11, while a holding electrode 16 is connected to a tip of an electrode 14 being inserted into this through hole 12, and the ceramic heater 11 is held between a flange 15 of an electrode body 13 and the holding electrode 16. And, a bonding material bank part 20 is installed in a circumferential part coming into contact with the electrode 14 of the holding electrode 16. A bonding material layer 17 is interposed between the flange 15, the holding electrode 16 and the ceramic heater 11. With this constitution, since a superfluous bonding material being extruded at the time of joining is stored in the bond part, the bonding material is not filled up inside the through hole, any crack in the ceramic heater due to oxidation of the bonding material is preventable from occurring.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat generating device using a ceramic heater used for regenerating a filter for purifying exhaust gas such as collecting black smoke emitted from a diesel engine. .

[Background Art] For example, a ceramic heater used for regenerating a filter used in an exhaust gas purification processing device is attached to the upstream end of the filter, and heats and burns fine particles mainly composed of carbon collected in the filter. It is being played. Incidentally, the electrode structure for energizing the ceramic heater is usually constructed by pressing a metal electrode against the electrode portion of the ceramic heater. In this case, there are problems in that in order to reduce the contact resistance between the metal plate and the ceramic heater, the smoothness of the contact surface must be increased and the pressing force of the metal plate must be considerably increased.

Therefore, in order to solve the above problems, an electrode structure as shown in FIG. 5 has been devised.

In this electrode structure, a through hole 12 is formed in the electrode mounting portion of the ceramic heater 11, and an electrode body 18 is formed in the through hole 12.
The electrode rod 14 is inserted up to the flange 15, and the holding electrode 16 is fitted and fixed to the tip of the electrode rod 14, so that the ceramic heater 11 is held between the flange 5 and the holding electrode 16. In this case, since the electrode body 13 and the holding electrode 16 are made of metal with a relatively large coefficient of thermal expansion, for example, if this electrode structure is attached at a high temperature and then cooled to room temperature, the ceramic heater 11 The contraction of the electrode rod 14 of the electrode main body 13 is greater than the contraction, so that the ceramic heater 11 and this electrode structure are firmly connected.

In this case, in order to ensure that the flange 15 and holding electrode 16 are in contact with the ceramic heater 11, a conductive bonding material layer 17 is interposed between them. Further, a gap is formed around the electrode rod 14 so that unnecessary stress does not act on the ceramic heater.

However, when configured as described above, the bonding material flows into the through hole 12 and accumulates in the set gap. This bonding material is used in a high temperature atmosphere such as 830°
It has the property of oxidizing and expanding in C. therefore,
If the ceramic heater 11 is operated as a heater in this state, the bonding material accumulated inside the through hole 12 will oxidize and expand, pushing the through hole 12 wider and causing cracks in the ceramic heater 11 .

[Problems to be Solved by the Invention] This invention has been made in view of the above points, and is intended to prevent accidents such as cracks occurring in ceramic heaters due to oxidation of bonding materials, and to improve electrode bonding. The present invention aims to provide a ceramic heating device with improved reliability.

[Means for Solving the Problems] That is, in the ceramic heating device according to the present invention, for example, a bonding material reservoir is provided at a position of the holding electrode facing the through hole of the ceramic heater, and the bonding material is This is to allow excess bonding material that comes out during the process to accumulate in this bonding material reservoir.

[Function] In the ceramic heating device configured as described above, even if the bonding material used to bond the electrode and the ceramic heater flows into the through hole for attaching the electrode, the bonding material will not flow. , accumulated in the bonding material reservoir. Therefore, the bonding material does not accumulate inside the through hole, and even when the ceramic heater is operated as a heater and reaches a high temperature, it is possible to prevent the ceramic heater from cracking due to oxidative expansion of the bonding material.

[Embodiment of the Invention] An embodiment of the invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the ceramic heater at the electrode junction. The ceramic heater 11 is provided with a through hole 12 serving as an electrode attachment portion, and the electrode rod 14 of the electrode body 13 is inserted into the through hole 12. The holding electrode 1B is coupled to the tip of the electrode rod 14 that penetrates through the through hole 12, so that the ceramic heater 11 is held between the collar 15 of the electrode body 13 and the holding electrode 16.

A bonding material reservoir 20 is provided at the circumferential portion of the holding electrode 1e that contacts the electrode rod 14. This bonding material reservoir 20
In this case, the through hole 12 is formed in accordance with the gap formed on the outer periphery of the electrode rod 14. In this case, between each of the collar 15 and the holding electrode 16 and the ceramic heater 11,
A bonding material layer 17 is interposed.

That is, the ceramic heater 11, the collar 15, and the protector;
b The contact surface with the I electrode 16 is coated with a bonding material made of, for example, Ni-Co-based wax, and the ceramic heater 11 is
The electrode rod 14 of the electrode body 13 is inserted into the flange 15 so as to sandwich the electrode rod 14.
The holding electrode 16 is inserted into the through hole 12 until the end of the holding electrode 16 is inserted into the through hole 12. The electrode main body 13 and the holding electrode 16 are made of, for example, Kovar, and have a diameter of 1100''.
When heat treatment is performed at C and cooled to room temperature, the contraction of the electrode body 13, especially the electrode rod 14, is greater than the contraction of the ceramic heater 11, so stress is applied to the contact surface between the collar 15 and the holding electrode 16 and the ceramic heater 11. The state will be as follows. Therefore, sufficient electrical bonding can be obtained without requiring external stress.

Note that at this time, the bonding material flows out into the gap set in the through hole 12. However, this excess bonding material that has flowed out is accumulated in the bonding material warming portion 20 provided in the holding electrode 16, and therefore does not fill the inside of the through hole 12.

From the above, when operated as a heater,
Even if the bonding material is oxidized and expands in volume, the ceramic heater 11 can be prevented from cracking because the bonding material is not filled in the through hole 12.

FIG. 2 is a diagram for explaining the durability of the electrode structure according to the present invention. As shown in the figure, when the heater was operated for 600 hours and the resistance at the joint was examined, the solid line A
The product of this example shown in 2 maintains almost the same resistance value even after 600 hours or more, and no resistance deterioration is observed. On the other hand, in the conventional type without the bonding material warming section 20, the resistance value increases after 100 hours as shown by the dotted line B, and resistance deterioration is observed around 200 hours. Cracks begin to form near the area.

3 and 4 are diagrams for explaining the structure of the ceramic heater 11. FIG. The ceramic heater 11 is made of conductive ceramic and includes a heat generating part 30 and two electrode parts 31.
a and 31b. The heat generating portion 30 is provided with openings 32a to 32c as shown in the figure. Also,
Metal electrodes 33a are provided in the electrode parts 31a and 31b, respectively.
and 33b are attached in the same manner as in the embodiment shown in FIG. 1 above. These two metal electrodes 33
When a voltage is applied from a battery (not shown) between a and 33b, the heat generating portion 30 of the ceramic heater 11 is configured to generate heat.

In addition, in the above embodiment, the bonding material warming portion was formed only on the holding electrode, but it may be formed in correspondence with the flange of the electrode body to more reliably connect the through hole of the bonding material. It is possible to prevent entry into the

[Effects of the Invention] As described above, according to the present invention, by providing a bonding material warming portion corresponding to the electrode mounting portion and bonding, the excess bonding material that comes out during bonding is removed from the bonding material. It will accumulate in warm areas. Therefore, the inside of the through-hole of the electrode is not filled with the bonding material, it is possible to prevent the generation of cracks in the ceramic heater due to oxidation of the bonding material, and a highly reliable electrode structure can be obtained.

[Brief explanation of drawings]

FIG. 1 is a folded view of a ceramic heating device according to the present invention, FIG. 2 is a diagram for explaining the invention in detail, and FIG.
The figure is a front view of the ceramic heater, FIG. 4 is a partial view of FIG. 3, and FIG. 5 is a sectional view of a conventional ceramic heating device. 11... Ceramic heater, 12... Through hole, 13
... Electrode body, 14 ... Electrode rod, 15 ... Tsuba, 1
6... Holding electrode, 17... Bonding material layer, 20...
Warm part of bonding material. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 3 Figure 4

Claims (1)

[Scope of Claims] A ceramic heater having a through hole for taking out an electrode, an electrode body having an electrode rod inserted into the through hole of the ceramic heater, and having a flange formed at its base; is attached to the tip of the above electrode rod,
A holding electrode that holds the ceramic heater on both sides of the through hole; and a bonding material reservoir formed between the holding electrode or the collar of the electrode body and the electrode rod. Ceramic heating device.