JPS5843238A - Structural body of ceramic honeycomb and its production - Google Patents

Abstract

PURPOSE:To improve the purification efficiency of waste gases and the buffer effect against thermal impact by forming the structural body of ceramic honeycomb in such a way that plural penetrating fluid passages thereof snake from an inlet toward an outlet. CONSTITUTION:A honeycomb of a straight pipe is extruded through an extrusion die part 12 of an extrusion molding machine 11. The preceding end part thereof is gripped with a chuck 14 and the extrudate is rotated in the direction at right angles to the longitudinal direction of the molded extrudate. More specifically, an extruded molding 13 is rotated circumferentially and the rotation is reversed. By the reiterative repetition of these rotations, snaking is formed, and the fluid passages of the honeycomb are formed to desired snaking shapes by controlling the extrusion molding speed thereof, and the rotating speed and distance of the molding. Thus the contact surface area of the fluid at the specified length of such structural body is increased, and the mutual effect of the wall surfaces of the penetrating holes and the fluid is increased, whereby the purification efficiency for waste gases is improved. Since the snaking is larger in the parts nearer the outside circumferential parts of the structural body, a buffer effect against thermal impact is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic honeycomb structure and a method for manufacturing the same, and more specifically to a structure in which honeycomb fluid passages have a meandering shape and are suitable for use in purifying exhaust gas of internal combustion engines, etc. and its manufacturing method.

Ceramic honeycomb structures are lightweight, have secondary abrasion resistance, heat resistance, and a certain level of strength, and are therefore widely used as supports for automobile exhaust gas purification catalysts.

The ceramic honeycomb structure mentioned above is generally produced by extrusion molding method.
By being molded by an injection molding method or the like, the through hole serving as a fluid passage is parallel to the extrusion direction and is a direct pipe. When this conventional honeycomb structure is installed in the exhaust gas passage of an internal combustion engine, the exhaust gas inflow direction and the through holes of the honeycomb structure are in the same direction, which has the advantage of low ventilation resistance. This has the disadvantage that the interaction between the gas and the wall surface of the through hole is reduced.

Therefore, it is inefficient when collecting and purifying fine particles such as carbon in the exhaust gas on the wall surface of the through hole. Further, when the ceramic honeycomb structure is used as a heat exchanger, the interaction between the fluid and the wall surfaces of the through holes is small and the efficiency of heat exchange is reduced, as described above.

The present invention has been made in order to solve the above-mentioned drawbacks, and provides a cylindrical structure in which the fluid passage of the structure meanders from the inlet to the outlet, and allows the fluid passage to be adjusted as desired. The present invention provides a method for manufacturing a ceramic honeycomb structure formed into a meandering shape.

In the ceramic honeycomb structure of the present invention, since the structure meanders from the inlet to the outlet, the contact surface area of the fluid is increased over a certain length of the structure, and the interaction between the through hole wall surface and the fluid is increased. As a result, the purification efficiency of the exhaust gas is improved, and carbon particles in the exhaust gas are more likely to be collected in the pores of the structure passage. In addition, since the outer peripheral part of the honeycomb structure has a large □f% meandering, it has a buffering effect against thermal shock. The temperature improved by 100℃.

The meandering shape of the present invention is shown in the perspective view of FIG. 7, in which Figure A shows a configuration consisting only of a meandering curved pipe, and Figures B and 0 show a combination of a meandering pipe and a straight pipe.

By further changing the meandering pitch from the shapes shown in Figures A, B, and 0, a desired shape can be formed. The reasons for excluding the structure in which the penetrating fluid passage is formed in a spiral shape in the present invention are that the molded body deforms and it is difficult to form the desired shape, and that when installed in the exhaust gas passage of an internal combustion engine, the exhaust gas and the penetrating This is because it was determined that the interaction with the hole wall surface was relatively small and the purification efficiency was not much different from that of conventional direct pipes.

As described above, as a manufacturing method for a ceramic honeycomb structure, a device that rotates the extruded product in the circumferential direction from the extrusion mouth metal part of the extrusion molding machine in the longitudinal direction of the molded extruded product to meander is installed, and the molding extrusion speed is adjusted to Turns y″゛”One glance, Seven”””°“Pa=””
4 channels can be formed into a desired serpentine shape.

Furthermore, the extrusion die part of the honeycomb used for this
1 and the device is disclosed in Japanese Unexamined Patent Publication No. 4, filed recently by the present inventor.
44-17743 and JP-A-Sho t+-1ltoix
It is desirable to apply the molding die disclosed in the extrusion die part and extrusion device of a honeycomb structure to use a forming die that allows extrusion discharge speed to be faster in the outer peripheral part than in the central part. It is also preferable to use a honeycomb extruded material whose fluidity is increased by heating a portion of the extrusion cylinder to soften the outer circumference of the honeycomb extruded material. With common ferrules and equipment, the outer diameter of the extruded product becomes distorted and cracks occur. In addition, the present inventor has filed an application for Japanese Patent Application Laid-Open No. 2003-29003 and JP-A-3. z-i
The binder of the extruded material disclosed in the extrusion molding method for inorganic materials of iλOj is preferably a rubber-like flexible resin during curing during molding, and it is preferable to use a polyurethane resin that hardens in a few seconds. It is suitable for

Hereinafter, the present invention will be explained in more detail with reference to Examples.

A central cross-sectional view of the extrusion molding apparatus according to the embodiment is shown in FIG.
3.Add water-curing polyurethane resin to ceramic powder of cordierite composition consisting of jsioi, put in a cross-wired base material, extrude a straight pipe honeycomb from an approximately 30m extrusion die/J, and hold the tip of the honeycomb with a chuck of 14t. grasp. This chuck l is operated by a variable motor /j to gears /l, /7. /I rotates and transmits the drive.

Still, the chuck/l can be moved along the shaft axis, and the rotational speed and rotational distance can be determined by the controller 2j to achieve a desired meandering. Chuck 14! and gear lt
Unlike the shaft 15', the base 20 and the bearing, 2/ are attached to the water tank 2.2 of the underwater 27, and the chuck part of the chuck / 4t and the gear, / Ir and the base 20 are used to extrude the honeycomb 13. It has a structure in which it moves downward by pressure, and the balance of the outer diameter, length, extrusion speed, weight of the chuck part, etc. of the honeycomb/3 is adjusted using the lever 23. The meandering shape of the honeycomb is determined by adjusting the extrusion speed, chuck rotation speed, and rotation distance.

In the above method, the extrusion speed was 2 o o wa/min, the chuck rotation speed was 0.1 rpm, the I-chan 2 rotation repetition rate was 1 g times/min, the outer diameter tθ--, the length/λ0, the pitch of the fluid passage through the dragon 2, t, 27 Adjustment, fluid passage wall thickness 0. /jm+The fluid passage shape is square and has a meandering pitch P, 2! as shown in Figure 1A. The meander-forming bacteria of - were molded into a shape that combines the meandering tube and straight tube shown in Figures B and 0, and a conventional straight tube was prepared as a comparison product for 2 hours in a dry layer at 1 aoooC. It was fired to form a honeycomb structure. Among these samples, the characteristics of three each of the shapes shown in Figures A and 0 were measured and are shown in Table 1 and Figure 3 below.

1 to 11 degrees (7) As is clear from the table above, the structural products of the present invention not only increased in surface area and bulk density, but also improved thermal shock resistance by about 100°C. Thermal shock resistance is -20% during electric furnace heating temperature.
After holding for a minute, it was taken out to λSC in air and the cooling layer and cracks were investigated.

In addition, the relationship between wind speed and pressure loss was investigated and shown in Figure 3.The shape of the product with the meandering fluid passage shown in Figure A is indicated by a broken line, the shape of the product shown in Figure 0 is indicated with a dotted line, and the comparative product with a straight passage pipe is indicated with a solid line. It is expressed. The honeycomb structured product of the present invention has a ventilation resistance that is approximately 30 - higher than that of conventional soft bacteria. It is clear that this improves the efficiency of collecting and purifying fine particles such as carbon in the exhaust gas on the wall surface of the through hole.

The honeycomb structure of the present invention has the above-mentioned superior properties compared to conventional products, and the manufacturing method thereof allows the required serpentine-shaped product to be easily formed using simple equipment.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a honeycomb structure according to the present invention, in which Fig. A shows a product in which the through-flow fluid passage is shaped like a meandering pipe, Figs. FIG. 2 is a cross-sectional view of the device that forms the meander, and FIG. 3 is a related curve representing the ventilation resistance. /, 4A, 7... Ceramic honeycomb structure, Ko,!
...through-fluid passage, 3. t...Meandering passage, l/...
・Cylinder, 7.2...cap, /3...extrusion,
14t... Chuck, l! ···motor,# , /
7, /I...gear, /? ...shaft, 20
...pace, 2/...bearing, 2.2...water tank, 2
3... Gun 1.21... Water, 2j... Controller (10)

Claims (2)

[Claims] (1) A cylindrical ceramic honeycomb structure having a plurality of through fluid passages, wherein the through fluid passages meander from an inlet toward an outlet. (2) Install a device that rotates the extruded product from the extrusion mouthpiece of the extrusion molding machine in a direction perpendicular to the length direction of the molded extruded product, and rotates the extruded molded product in the circumferential direction and reverses the rotation. The honeycomb is rotated to repeatedly form a meandering shape, and the extrusion speed, rotational speed of the molded body, and rotation distance are adjusted to form the fluid passages of the honeycomb into a desired meandering shape. A method for manufacturing a ceramic Nicam□ structure.