JPS61142316A - Exhaust gas purifying device with slip layer - Google Patents

Abstract

PURPOSE:To prevent a honeycomb catalyst from its destructive failure while maintaining a sealing characteristic of a seal mat, by housing the ceramic made honeycomb catalyst in a metallic case through the seal mat which has at least on its one side a slip layer and is formed by a heat resisting fiber. CONSTITUTION:A ceramic made honeycomb catalyst 1 is contained in a case 3 made of stainless steel through a cushion 2 consisting of a wire net. Here a clearance between the case 3 and the honeycomb catalyst 1 is charged with a seal mat 4 having a slip layer 4a. And the seal mat 4 is arranged so that its slip layer 4a is placed in a side of the honeycomb catalyst 1. While the seal mat 4 contains a heat expanding agent. In this way, the ceramic made honeycomb catalyst 1 can be prevented from its destructive failure while maintaining an excellent sealing characteristic of the seal mat 4 consisting of a heat resisting fiber.

Description

[Detailed Description of the Invention] [Field of Application] The present invention relates to a novel sliding layer material exhaust gas that prevents breakage of ceramic honeycomb catalysts for purifying gases emitted from various engines such as gasoline engines and diesel engines. 0 [Prior Art] Conventionally, a honeycomb catalyst for purifying exhaust gas consists of a ceramic cylinder body integrally formed in a honeycomb shape and a catalyst, and the catalyst is wound around the side shoulder of a honeycomb catalyst for purifying exhaust gas. Sealing mats made of heat-resistant fibers (for example, Intatummat [trade name] manufactured by 3M Company in the United States, which is made by bonding ceramic fibers and vermiculite with a binder) are known. This sticker mat is
The previous method of wrapping a corrugated wire mesh around the side shoulders of the honeycomb catalyst resulted in exhaust gas leakage of 5% to 7, so this method was devised as a poor method to improve sealing performance. ◎ [Problem to be solved] The above sealing mat is wrapped around the side shoulder of a ceramic honeycomb catalyst and housed in a metal case, but at that time, it is necessary to improve the sealing performance. Therefore, it is necessary to apply the seal mat in a compressed state within the purification device.

However, there is a problem in that the ceramic honeycomb catalyst in the device breaks during use when the device is mounted in an automobile or the like. In many cases, fracture occurs approximately at the center of the honeycomb catalyst. [Means for solving the problem] The present invention overcomes the above problems while taking advantage of the excellent sealing function of the seal mat made of heat-resistant fibers. This was done for that purpose.

That is, the present invention uses a ceramic honeycomb catalyst,
The present invention provides an exhaust gas purification device housed in a metal case via a seal mat made of heat-resistant fibers having a slip layer on at least one side.

[For production]

In the present invention, the sliding layer has a tensile force applied to the honeycomb catalyst in the length and width directions through the seal mat, which is caused by the large difference in thermal expansion coefficient between the ceramic honeycomb catalyst and the metal case that houses it. In other words, the metal case expands as the temperature of the purification device increases while it is in use.
When the seal mat also tries to expand following this expansion, the tensile force acting on the ceramic honeycomb catalyst with an extremely small coefficient of thermal expansion is relaxed or eliminated, effectively preventing the honeycomb catalyst from breaking. It is for.

In particular, if the seal mat contains a thermally expandable additive such as vermiculite and has thermal expansion properties, the frictional force will increase due to the increase in surface pressure due to the thermal expansion. However, the tensile force is greatly alleviated by the action of the sliding layer, and breakage of the honeycomb catalyst is effectively prevented.

〔Example〕

In the embodiment shown in the attached drawings, a ceramic honeycomb catalyst 1 is housed in a stainless steel case 3 via a wire mesh shoe 2, and a gap between the case 3 and the honeycomb catalyst 1 is provided. is filled with a seal mat 4 having a sliding layer 4a. The seal mat 4 is made of, for example, asbestos, rock wool, ceramic fiber, carbon fiber, glass fiber, puffer wool, or metal fiber in order to withstand the high temperature of exhaust gas. It is made from heat-resistant fibers such as.

A material made of fine fibers is preferably used from the viewpoint of airtightness.

For example, seal mats are produced using nonwoven fabrics made of heat-resistant fibers.
This can be done by impregnating a heat-resistant adhesive such as an alkali metal silicate-based inorganic adhesive, a phosphate-based inorganic adhesive, or an alkyl silicate-based inorganic adhesive and laminating the same, or by laminating aluminum powder, Liquid adhesives containing substances that have a lower melting point than the heat-resistant fibers used, such as calcium powder, lead powder, barium powder, sodium chloride, and calcium chloride, and that melt at a temperature higher than the temperature of the exhaust gas entering the purification device. Impregnating a nonwoven fabric of heat-resistant fibers with the agent and laminating them, heat-treating the formed mat to melt the substance, and then cooling and solidifying it to obtain a mat with heat-resistant fibers bonded with the substance. It can also be done by

The seal mat used in the present invention also contains a heat-expandable agent,
For example, a suitable amount of vermiculite, expandable mica, expandable graphite, nacre, etc. may be contained, for example, 1 to 100 parts by weight per 100 parts by weight of the heat-resistant fibers. Conventionally, when a seal mat containing a heat-expandable agent was used, there were many accidents, especially the breakage of the honeycomb catalyst described above, so the present invention has a remarkable effect when using such a seal mat. .

In the embodiment, the sliding layer 4a functions to improve the sliding between the seal mat 4 and the honeycomb catalyst 1. It is possible to use various materials and shapes as long as they can perform such an action. For example, sheets or wire mesh made of heat-resistant metals such as stainless steel, zirconium, or copper, or powders or sintered materials of heat-resistant inorganic substances such as starch disulfide, silicon nitride, and graphite are used. Although the sliding layer 4a and the seal mat 4 do not necessarily have to be integrally connected, it is preferable that they be integrally connected in terms of high efficiency and productivity of the apparatus of the present invention. Further, in the present invention, a sliding layer may be provided between the metal case and the seal mat or on both sides of the seal mat.

〔Effect of the invention〕

According to the present invention, since the sliding layer is provided, it is possible to reduce or eliminate the incidence of breakage accidents of ceramic honeycomb catalysts while taking advantage of the excellent sealing properties of the seal mat made of heat-resistant fibers.

[Application examples, comparative examples]

Intatum mat (product name,
(manufactured by 3M Company, USA) was wound once around the side circumference of a ceramic honeycomb catalyst having a diameter of 10aII and a length of 200mm, and this was pressed into one half of a stainless steel case. The gap between the honeycomb catalyst and the inner surface of the case upon completion of compression is 2.
It was off. Next, predetermined welding points were welded to produce a purifying device. The exhaust gas purification device of this comparative example is
5 heat cycles of holding at 800'C for 1 hour under 0G vibration and then holding at room temperature for 5 hours without vibration.
When repeated several times, breakage was observed in the center of the honeycomb catalyst in 5 out of 10 samples. On the other hand, the thickness was 41n+, the width was 163, and the compressibility in the thickness direction at room temperature was 6.
Except that an Intatum mat with a compression resistance of 90 # f /d at 5% and a stainless steel plate with a thickness of 0.51 El was used, with the layer of the stainless steel plate facing the honeycomb catalyst side. A purifying device as an example of the present invention was obtained in the same manner as in the comparative example, and a cycle test was conducted on the purifying device. As a result, no breakage occurred in the honeycomb catalyst in any of the 1O samples.

[Brief explanation of the drawing]

The figure is a sectional view of an embodiment of the invention. 1: Ceramic honeycomb catalyst, 3: Metal case,
4: Seal mat made of heat-resistant fiber, 4a: Slip layer. Patent applicant: Nippon Linez Co., Ltd. Former Dainichi Nippon Electric Cable Co., Ltd. Tsutomu Fujimoto

Claims (1)

[Scope of Claims] 1. An exhaust gas purification device comprising a ceramic honeycomb catalyst housed in a metal case via a seal mat made of heat-resistant fibers and having a sliding layer on at least one side. 2. The device according to claim 1, wherein the seal mat has a sliding layer on at least one side, and the seal mat is interposed so that the sliding layer is on the side of the ceramic honeycomb catalyst. 3. The apparatus according to claims 1 and 2, wherein the seal mat contains a heat-expandable agent.