JPH11277653A - High strength thin wall honeycomb structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage of an outer peripheral wall and corner of a honeycomb structure by improving in good balance an isostatic strength and heat resistant impact resistance of the thin-walled honeycomb structure. SOLUTION: The honeycomb structure 1 comprises a plurality of cell passages 3. A thickness tc of a basic cell partition 2b of a cell partition 3 for constituting the structure 1 is tc<=0.11 mm, a thickness ts of an outer wall 4 is ts>=0.2 mm, an open area ratio of a thick part of the partition 2b is 80% or more, and a thickness tr of the outermost circumferential cell partition 2a and a thickness tc of the partition 2b and a thickness ts of the wall 4 have the relationships of formulae of 0.7<=tc/tr<=0.9, and 0.3<=tr/ts<=0.7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a high-strength thin-walled honeycomb structure that can be suitably used as a carrier for an automobile exhaust gas purifying catalyst or the like.

[0002]

2. Description of the Related Art Conventionally, a honeycomb catalyst for purifying an automobile exhaust gas has a structure in which a honeycomb carrier (honeycomb structure) is held in the axial direction of the honeycomb carrier because the axial strength of the honeycomb carrier is higher than that in a cross-sectional direction. However, in order to prevent breakage near the outer periphery when gripping in the axial direction, the cell partition walls (ribs) at the outer periphery are made thicker than the inside, thereby increasing the axial pressure resistance of the honeycomb carrier.

However, recently, due to the demand for reduction of pressure loss in the honeycomb catalyst due to the trend toward higher output of the engine, and the effective use of the entire catalyst carrier due to the tightening of exhaust gas regulations, the honeycomb catalyst carrier is not gripped in the axial direction. A structure in which the outer peripheral surface of the catalyst carrier is mainly held has begun to be adopted.
This was partly due to the fact that the catalyst volume increased and the catalyst mass increased due to stricter exhaust gas regulations, so that the gripping area in the axial gripping was too small for the engine vibration and the gripping could not be performed sufficiently.

On the other hand, in order to improve the purification performance of the catalyst, the thickness of the cell partition walls of the honeycomb carrier is reduced to reduce the weight of the honeycomb carrier, so that the heat capacity of the catalyst is reduced and the warm-up characteristics of the purification performance are reduced. The movement to improve is starting.

[0005] For this reason, the breaking strength due to external pressure from the outer peripheral surface of the honeycomb carrier tends to further decrease due to the thinning of the cell partition walls. Furthermore, the exhaust gas temperature has been increasing year by year with the aim of improving engine combustion conditions and catalyst purification performance in order to further strengthen the recent exhaust gas regulations, and the thermal shock resistance required for honeycomb carriers has also become severe. Is coming. As described above, the thickness of the outer peripheral wall of the honeycomb carrier has become a serious problem due to recent thinning of the cell partition walls, the use of the outer peripheral surface of the honeycomb carrier, and an increase in the exhaust gas temperature.

[0006] In view of the above, Japanese Patent Publication No. 54-1101
No. 89 proposes a structure in which the thickness of the helip of the honeycomb carrier in the center direction in the cross section is regularly reduced. However, in this structure, the partition wall cannot be made thinner over the entire honeycomb carrier. This is a problem in characteristics. Further, it is not preferable in terms of pressure loss.

In Japanese Patent Application Laid-Open No. 54-150406 or Japanese Patent Application Laid-Open No. 55-147154, a structure is proposed in which the outer cell partition is thicker than the inner cell partition. Nothing is mentioned about the wall thickness, and nothing is described about the relationship between the outer peripheral wall thickness and the cell partition. Further, in these prior arts, the thickness of the outer peripheral wall was not a problem because the honeycomb structure had a thick internal partition wall thickness of 0.15 mm or more and was gripped in the axial direction. It was merely pointed out that if the outer peripheral wall thickness is too thick, the thermal shock resistance is reduced.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and has as its object the isostatic strength and thermal shock resistance of a thinned honeycomb structure. The present invention provides a high-strength thin-walled honeycomb structure capable of improving the balance of the honeycomb structure and preventing damage to the outer peripheral wall and corner portions of the honeycomb structure.

[0009]

That is, according to the present invention, there is provided a honeycomb structure having a plurality of cell passages, and the basic cell partition wall thickness (tc) of the cell partition walls constituting the honeycomb structure is tc. ≦ 0.11 mm, outer wall thickness (t
s) is ts ≧ 0.2 mm, the opening ratio of the basic cell partition wall thickness portion is 80% or more, and the outermost peripheral cell partition wall thickness (tr), the basic cell partition wall thickness (tc), and the A high-strength thin-walled honeycomb structure is provided in which the outer wall thickness (ts) has the following relationship. 0.7 ≦ tc / tr ≦ 0.9 0.3 ≦ tr / ts ≦ 0.7

In the present invention, within a range of three cells from the outermost periphery of the honeycomb structure toward the inside,
The partition wall thickness is set to 0.
It is preferable to increase the thickness at a ratio of 7 ≦ tc / tr ≦ 0.9. In the high-strength thin-walled honeycomb structure described above, the portion where the outermost peripheral cell partition of the honeycomb structure is in contact with the outer wall is built up, or the adjacent partition is in contact with the outer wall while the space between the partitions is narrowing. It is more preferable to build up the inside of the outer wall at least between the partition walls.

Further, according to the present invention, there is provided a honeycomb structure having a plurality of cell passages, wherein a basic cell partition wall thickness of a cell partition wall constituting the honeycomb structure is 0.11 mm or less, and an outer wall thickness is zero. .2 mm or more, an opening ratio of the basic cell partition wall thickness portion is 80% or more, and a portion where the outermost cell partition and the outer wall of the honeycomb structure contact each other is built up. A wall honeycomb structure is provided. Further, according to the present invention, it is a honeycomb structure having a plurality of cell passages, wherein a basic cell partition wall thickness of a cell partition wall constituting the honeycomb structure is 0.11 mm or less, and an outer wall thickness is 0.2 mm or more. Where the opening ratio of the basic cell partition wall thickness portion is 80% or more and the adjacent partition walls are in contact with the outer wall while the space between the partition walls is narrowing,
A high-strength thin-walled honeycomb structure characterized by being built up on the inside of an outer wall at least between the partition walls.

In the present invention, it is preferable that the cell shape of the honeycomb structure is any one of a square, a rectangle, a rhombus, and a hexagon. Also, the honeycomb structure is
It is preferable to be formed of ceramic materials such as cordierite, alumina, mullite, silicon nitride, and silicon carbide. Further, the high-strength thin-walled honeycomb structure of the present invention is suitably used as a carrier for an automobile exhaust gas purification catalyst, and generally, a catalyst component is carried on the surface of a cell partition wall, and the outer peripheral surface of the structure is generally used. It is gripped and incorporated into a catalytic converter.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The mainstream of the honeycomb carrier is a cordierite ceramic material, and the honeycomb carrier is formed into a honeycomb structure by extrusion using a die having a lattice-shaped slit, dried, and fired to obtain a product. Conventionally, there was no problem when the partition wall thickness was as thick as 0.15 mm or more, but when the partition wall thickness is thin, since the partition walls are easily deformed during extrusion molding, when the isostatic strength test of the obtained fired body is performed At the deformed portion of the partition wall, the partition wall is broken with low strength.
If the partition wall is formed straight, when pressure is applied from the outer peripheral surface, it theoretically becomes a compressive stress field, and the honeycomb structure is destroyed by buckling of the partition wall or buckling of the outer wall. If the partition wall is deformed or the outer peripheral wall thickness is extremely thin, a bending stress, that is, a tensile stress is generated in the partition wall at that location. In general, the tensile strength is much lower than the compressive strength, especially for ceramic materials, where the ratio of the tensile strength to the compressive strength is about 1/10, and the tensile strength is much lower than the compressive strength compared to about 1/3 for metallic materials . Therefore, if the partition is deformed, the partition will be broken at a considerably lower strength than usual. In addition, the thin-walled honeycomb structure causes a problem that the corners of the honeycomb are lost or the outer wall is isolated when the honeycomb carrier is gripped and stored in the converter or in the handling or transporting process of the carrier.

A honeycomb carrier for an automobile exhaust gas purifying catalyst carrier is required to have not only a catalyst carrying performance but also a structure having “isostatic strength”, “thermal shock resistance”, and “outer wall corner strength”. Isostatic strength
Usually, when adopting the structure by gripping the outer peripheral surface of the carrier, the gripping surface pressure is a minimum guaranteed value of 0.5 MPa, desirably 1.0 MPa, for this reason, the average level of the isostatic strength of the carrier is 3.0 MPa or more, desirably. Is required to be 4.0MPa or more. Regarding thermal shock resistance, the exhaust gas temperature is increasing year by year, and the thermal shock resistance required for honeycomb carriers is also becoming severer.The thermal shock resistance is practically 750 ° C or more, preferably 800 ° C The above is required.

[0015] In addition, the honeycomb carrier is loaded with a catalyst in the catalyzing step and then is held in the can of the converter. In some cases, the carriers are in contact with each other or are damaged. Therefore, to evaluate the strength of the carrier during transport,
The end face of the carrier was pressed against a thick rubber plate, and the strength of the outer wall corner was evaluated by generating stress concentration at the outer wall corner of the carrier with the force that the rubber extends outward when a pressing load was applied. . When a carrier of each strength was applied to the process, it was found that the carrier outer wall corner strength was 3.5 kN or more, the damage during transportation was small, and that the carrier outer wall corner strength was hardly generated at 4.0 kN or more.

Conventionally, it has been considered that increasing the outer peripheral wall thickness can increase the strength against the outer peripheral surface pressure. However, the outer diameter is actually 90 mm, the length is 110 mm, the cell shape is square, and the partition wall thickness is increased. 0.11 mm, cordierite thin-walled honeycomb structure with 600 cpsi cells (separation between walls 1.04 mm) with outer wall thickness of 0.1 to 0.9
As shown in FIG. 8, as a result of producing a sample having a thickness of up to 0.4 mm and performing an isostatic strength test, the strength did not improve even if the outer wall thickness was more than 0.4 mm, and on the contrary, it tended to decrease. . Here, the cell number of 600 cpsi is 60 per square inch.
It means that there are 0 cells, cpsi is cells
Persquare inch. On the other hand, if the outer wall thickness is too thin, the outer wall is broken from the outer peripheral wall due to insufficient rigidity of the outer wall.

Therefore, the inventors investigated the reason why the isostatic strength was not improved simply by increasing the thickness of the outer peripheral wall. As the outer wall thickness was increased, the molded body immediately after extrusion molding was used to form the partition walls (ribs) of the outer peripheral cell. It was found that the deformation was large and the amount of the deformed partition wall also tended to increase. This is because when the raw material passes through the slit of the die at the time of extrusion molding, if the outer wall thickness is increased, the flow rate of the raw material through the slit forming the outer peripheral wall increases, so that the ribs of the outer peripheral cell are dragged toward the outer wall. This was due to the remarkable imbalance between the raw material flow on the outer wall and the raw material flow on the partition walls. Another major factor is that the partition walls themselves tend to be buckled and deformed as they become thinner. After extrusion molding, the honeycomb structure is received on the outer peripheral surface with a jig,
At that time, the outer wall and the outer peripheral partition may be deformed by the weight of the honeycomb structure.

According to the material mechanics, the buckling strength is basically given by the following equation, and the buckling strength is proportional to the square of the partition wall thickness. It can be seen that thinning of the partition walls has a very large effect on the strength of the honeycomb carrier. Buckling strength P = (kπ ² E) x (t / L) ² (k: coefficient, E: Young's modulus, L: partition length, t: partition thickness)

In the related art, since the partition wall thickness was large, the partition wall itself was not easily buckled and deformed, and the thickness was close to the outer wall thickness, so that imbalance during molding did not cause much problem. . When extruding with ceramic materials such as alumina, mullite, silicon nitride, silicon carbide, zirconia, etc. as well as cordierite, since the raw material water and binder are mixed and kneaded, the honeycomb structure in the extrusion molding process is used. The same theory holds for the deformation of the bulkhead of the body. As described above, the deformation of the partition wall is mainly caused by buckling due to the compression load. Therefore, the same problem occurs not only in the case of a square cell but also in a case of a rectangle, a triangle, and a hexagon. Also, as seen in the prior art, when the strength of a carrier whose outer peripheral wall was made thicker than the inner wall was measured, the strength was certainly improved, but when the thickness was too large, the strength tended to decrease. Was done. Examination of a carrier having a considerably increased outermost partition wall thickness revealed that the outermost partition wall was deformed. This is considered to be due to the same reasoning as increasing the thickness of the outer wall.

Further, after a carrier having a partition wall thickness of 0.11 mm was heated in an electric furnace for a predetermined time to obtain a uniform temperature, a supercooling thermal shock resistance test was taken out from the furnace, and as a result, as shown in FIG. It was confirmed that as the outer wall thickness was increased, the thermal shock resistance was reduced. However, the thermal shock resistance was more likely to be reduced when the outer wall thickness was 0.7 mm or more. This is presumably because the thickness of the outer wall increases the influence of the heat capacity of the outer wall itself, and the temperature difference between the inside and outside of the outer wall increases. JP-A-54 mentioned above
As seen in -150406, the idea of providing a cutout in the outer wall to reduce the heat capacity of the outer wall is effective if the outer wall is sufficiently thick, but in the case of an extremely thin partition wall having a partition wall thickness of 0.11 mm or less, However, the outer wall cannot be made too thick, and the effect of the notch cannot be expected. Conversely, there is a danger of reducing the rigidity of the outer wall.

FIG. 10 shows the results of evaluation of the outer wall corner strength. As the outer wall thickness decreases, the corner strength tends to decrease. In particular, when the outer wall thickness is smaller than 0.3 mm, the strength is reduced. In order to enhance the outer wall corner strength, simply increasing the thickness of the outer wall is effective. However, in the case of the above-mentioned isostatic strength, excessively thick outer wall tends to cause a reduction in strength. The same applies to the impact property, and it is not preferable to simply make the outer wall thick.

The present inventor has determined from the above various test results
In recent wall thinning of the partition walls of the honeycomb carrier, as seen in the prior art, it is not only necessary to thicken the partition walls constituting the outer peripheral cells simply considering the problem in use of the honeycomb carrier. In addition, the extrudability of the honeycomb structure must be taken into consideration. For this purpose, not only the relationship between the outermost peripheral cell partition wall thickness and the inner basic cell partition wall thickness, but also the outer wall thickness while considering the basic cell partition wall thickness. The inventors have thought that it is necessary to design the honeycomb structure while paying attention to the relationship between the honeycomb structure and the outermost cell partition wall thickness, and have completed the present invention. FIG. 11 schematically shows the relationship between the outermost cell partition wall thickness, the outer wall thickness and strength, and the thermal shock resistance.

Hereinafter, in the present invention, the basic cell partition wall thickness, the outer wall thickness, and the outermost peripheral cell partition wall thickness constituting the honeycomb structure will be described in detail. As described above, in the present invention, the basic cell partition wall thickness (tc) of the cell partition walls constituting the honeycomb structure is tc ≦ 0.11 m.
m, the outer wall thickness (ts) is ts ≧ 0.2 mm, the opening ratio of the basic cell partition wall thickness portion is 80% or more, and the outermost peripheral cell partition wall thickness (tr) and the basic cell partition wall thickness ( tc) and the outer wall thickness (ts) have a relationship of 0.7 ≦ tc / tr ≦ 0.9 0.3 ≦ tr / ts ≦ 0.7.

As described above, the honeycomb structure of the present invention is a thin wall in which the basic cell partition wall thickness tc of the cell partition walls constituting the honeycomb structure is 0.11 mm or less, and the outer wall thickness ts is 0.1 mm or less. Under the condition that the opening ratio of the basic cell partition wall thickness portion is 80% or more, the relationship between the outermost peripheral cell partition wall thickness tr and the basic cell partition wall thickness tc is 0.7.
≦ tc / tr ≦ 0.9, and the relationship between the outer wall thickness ts and the outermost peripheral cell partition wall thickness tr is 0.3 ≦ tr / ts ≦
By setting the range to 0.7, the "isostatic strength", "thermal shock resistance", and "outer wall corner strength" of the thinned honeycomb structure can be satisfied in a well-balanced manner.

Hereinafter, the high-strength thin-walled honeycomb structure of the present invention will be described in more detail. FIG. 1 (a) (b)
Shows an example of a honeycomb structure. The honeycomb structure 1 has a large number of through holes (cell passages) 3 partitioned by cell partition walls 2. 4 is an outer wall. FIG.
Is a partially enlarged view of the honeycomb structure, showing a portion represented by a term used in the present invention. An outermost peripheral cell 8 is closest to the outer wall 4, and 9 is a second cell from the outermost peripheral.
Reference numeral 10 denotes a partition wall of the outer peripheral cell.

FIGS. 3A and 3B show an example of a high-strength thin-walled honeycomb ellipsoid of the present invention. The honeycomb structure 1 has a plurality of cell passages 3 and basically has the following structure. The cell structure 2 and the outer wall 4 constitute the honeycomb structure 1. In the present invention, the cell partition 2 is divided into the basic cell partition 2b and the outermost cell partition 2a, and the relationship between the thicknesses of the basic cell partition 2b, the outermost cell partition 2a, and the outer wall 4 is defined. It was done. Reference numeral 5 denotes a boundary between the outermost cell partition 2a and the basic cell partition 2b.

That is, in the honeycomb structure 1 of the present invention, the thickness tc of the basic cell partition 2b is in the range of 0.7 to 0.9 times the thickness tr of the outermost cell partition 2a. This is the case when the basic cell partition wall thickness tc exceeds 0.9 times the outermost peripheral cell partition wall thickness tr, that is, the basic cell partition wall thickness tc is substantially the same as the outermost peripheral cell partition wall thickness tr. In this case, the breaking strength (isostatic strength) due to external pressure from the outer peripheral surface of the honeycomb structure cannot be sufficiently ensured. On the other hand, when the basic cell partition wall thickness tc is
When the outermost cell partition wall thickness tr is less than 0.7 times, the deformation of the outermost peripheral cell partition walls (ribs) during extrusion molding increases and the amount of deformed ribs increases. This is because the breaking strength (isostatic strength) due to the external pressure from the outer peripheral surface of the above decreases.

Further, in the honeycomb structure of the present invention, the thickness tr of the outermost peripheral cell partition wall 2 a is in a range of 0.3 to 0.7 times the thickness ts of the outer wall 4 of the honeycomb structure. This is because when the outermost cell partition wall thickness tr exceeds 0.7 times the outer wall thickness ts of the honeycomb structure, the breaking strength (isostatic strength) due to external pressure from the outer peripheral surface of the honeycomb structure is sufficient. The outer wall and corners are not
This is because they are easily damaged. On the other hand, when the outermost cell partition wall thickness tr is less than 0.3 times the outer wall thickness ts of the honeycomb structure, the outermost cell partition wall (rib) is formed at the time of extrusion molding.
This is because, as the deformation of the honeycomb structure increases, the amount of the deformation rib also increases, so that the breaking strength (isostatic strength) due to the external pressure from the outer peripheral surface of the honeycomb structure decreases.

At this time, as shown in FIG. 4, within a range of three cells from the outermost periphery to the innermost periphery of the honeycomb structure, the partition wall thickness is sequentially increased from the inner cells to the outermost peripheral cells by 0.7. By increasing the thickness at a ratio of ≦ tc / tr ≦ 0.9, the above “isostatic strength”, “thermal shock resistance”, and “outer wall corner strength” can be satisfied. In the honeycomb structure, the strength tends to decrease in a region where the ratio between the basic partition wall thickness and the partition wall thickness of the outermost peripheral cell is small, that is, in a region where the outermost peripheral rib thickness is relatively large. This is explained in the same way as described above, and is caused by the imbalance in the flow of the raw material in the die at the time of molding by the outermost partition and the inner partition. Therefore, the strength can be improved by increasing the thickness of the partition walls also for the cells inside the outermost peripheral cells. In this case, the rib thickness is gradually reduced toward the inside by only a few cells from the outermost periphery to match the basic rib thickness. The ratio of thinning may be in accordance with the range of the ratio between the basic partition wall thickness and the outermost peripheral partition wall thickness.

For example, when the thickness is increased from the outer periphery to the third cell, the ratio of the partition wall thicknesses of the inner cell, the third cell, the third cell and the second cell, the second cell and the first cell (the outermost cell) is respectively 0.
7 ≦ tc / tr ≦ 0.9, 0.7 ≦ tr ₃ / tr ₂ ≦ 0.9, 0.7 ≦
The ratio is set within the range of tr ₂ / tr ₁ ≦ 0.9, and is adjusted to the range of the ratio of tc / tr described above. It is desirable that the cells to be thickened are three cells from the outermost periphery. If the thickness is further increased to the inside, the pressure loss performance of the carrier is not negligibly affected. In addition, since the mass of the carrier becomes heavier than a predetermined amount, the heat capacity increases, which may affect the warm-up performance of the catalyst at the time of a cold start. In addition, within the range of three cells from the outermost periphery, there is practically no effect on the pressure loss.

As described above, the honeycomb structure in which the outer wall and the outermost peripheral cell partition wall are thickened in a predetermined range has been described. However, the honeycomb structure having such a configuration basically has a flow of raw material in a die at the time of molding. The imbalance is reduced. However, in the honeycomb structure having this configuration, there is another aspect that the weight of the honeycomb carrier increases due to the increase in the thickness of the entire wall of the outer peripheral portion. Therefore, in addition to this configuration, or as a means for further improving the characteristics of the honeycomb structure having this configuration, a portion where the outermost peripheral cell partition wall and the outer wall of the honeycomb structure are in contact is overlaid (contact overlaid).
In addition, it can be mentioned that adjacent partition walls are in contact with the outer wall while the space between the partition walls is narrowing, and at least between these partition walls, the inside of the outer wall is built up (V-shaped connection build-up).

FIG. 5 is a partial cross-sectional explanatory view showing one embodiment in which a honeycomb structure is provided with a contact overlay, and FIG. 6 is a partial cross-sectional view showing another embodiment in which a honeycomb structure is provided with a contact overlay. It is a figure and the outermost peripheral cell partition wall 2a of a honeycomb structure
An example is shown in which a portion where the outer wall 4 and the outer wall 4 are in contact is overlaid.
With such a configuration, it is possible to avoid an excessive increase in the thickness of the outer wall and suppress deformation of the cell partition. FIG. 7 is a partial cross-sectional explanatory view showing one embodiment in which a V-shaped connection buildup is applied to the honeycomb structure, and a portion (V) contacting the outer wall 4 while the space between adjacent partitions is narrowed at the outermost peripheral cell partition 2a.
In the U-shaped connection portion 7), the outer wall 4 was thickened inward by forming a buildup 6 on the inner side of the outer wall at least between the partition walls 2a. By employing such means, deformation of the partition wall (rib) can be suppressed, and the isostatic strength can be improved.

The amount of the build-up is preferably で or more of the length of the outermost cell partition 2 a,
/ 3 or more is more preferable. The cell shape of the honeycomb structure of the present invention is not particularly limited, but is preferably any one of a square, a rectangle, a rhombus, and a hexagon. Further, the honeycomb structure of the present invention is preferably formed of a ceramic material such as cordierite, alumina, mullite, silicon nitride, and silicon carbide.

Further, the high-strength thin-walled honeycomb structure of the present invention is suitably used as a carrier for an automobile exhaust gas purifying catalyst, and usually, a catalyst component is supported on the surface of a cell partition wall.
It is gripped on the outer peripheral surface of the carrier and incorporated into the catalytic converter. FIGS. 12A and 12B are explanatory views showing an example in which a honeycomb carrier is incorporated in a converter container. A honeycomb carrier 13 is incorporated in a converter container 11 by being held by a ring 12 on the outer peripheral surface thereof.
The ring 12 is usually made of a metal mesh, but is not limited to this. Reference numeral 14 denotes a buffer member such as a mat or cloth interposed between the converter container 11 and the outer peripheral surface of the honeycomb carrier 13.

[0035]

EXAMPLES Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Incidentally, the honeycomb structure obtained in the example,
The performance was evaluated by the following method.

(Isostatic Strength Test) In this test, a carrier is placed in a rubber cylindrical container, covered with an aluminum plate, and subjected to isostatic pressing under water. This is a test that simulates a compressive load when the outer peripheral surface is gripped. The isostatic strength is indicated by a pressurized pressure value at the time when the carrier is broken, and is specified in the automotive standard JASO standard M505-87 issued by the Japan Society of Automotive Engineers.

(Thermal shock resistance test) In this test, a honeycomb carrier at room temperature was placed in an electric furnace maintained at a temperature higher than room temperature by a predetermined temperature, held for 20 minutes, then the carrier was taken out on a firebrick, and the appearance was observed. This is a test in which the outer periphery of the carrier is lightly tapped with a metal rod. If no cracks were observed on the carrier and the tapping sound was not a dull metal sound, the test passed and the temperature in the electric furnace was raised to 50
Each time the temperature is raised in steps of ° C, the same inspection is repeated until the test is rejected. If the test fails at a temperature 950 ° C. higher than room temperature, the thermal shock resistance is 900 ° C. different.

(External wall corner strength test)
In a test in which a honeycomb carrier is placed on m m neoprene rubber and a load is applied downward from the upper part of the carrier through an aluminum plate with a urethane sheet attached, the strength is the load when the outer wall of the carrier in contact with the neoprene rubber breaks. Indicated by value.

(Examples 1-33, Comparative Examples 1-37) In order to improve the outer peripheral strength, as shown in Tables 1 and 2,
The thickness of the partition wall constituting the outermost peripheral cell is made thicker than the thickness of the internal basic cell partition wall, and various types of honeycomb carriers with different outer wall thicknesses are manufactured to produce "isostatic strength test" and "thermal shock resistance test". , "Outer wall corner strength test" was performed. The results are shown in Tables 1 and 2.

The samples used in the examples were talc,
A cordierite honeycomb structure (carrier) having a diameter of 106 mm and a length of 155 mm obtained by extruding and firing a kneaded raw material such as kaolin and alumina. The number of cells shown in Tables 1 and 2,
Various honeycomb carriers having the basic cell partition wall thickness, the outermost cell partition wall thickness, and the outer wall thickness were prepared.

[0041]

[Table 1]

[0042]

[Table 2]

As is clear from the results of Tables 1 and 2, when the basic cell partition wall thickness is 0.17 mm and the opening ratio of the honeycomb carrier is less than 80%, the outer peripheral partition wall as seen in the prior art is formed. Although it had sufficient "isostatic strength", "thermal shock resistance", and "outer wall corner strength" even if it was not thickened, the basic partition wall thickness was 0.11 mm or less and the carrier opening ratio was 80%.
In the case described above, sufficient characteristics cannot be obtained with a structure in which the outer peripheral wall is not thickened. Also, from the results of Tables 1 and 2, “isostatic strength”, “thermal shock resistance”,
In order to satisfy all the “outer wall corner strength”, the thickness between the basic cell partition wall thickness (tc) and the outermost peripheral cell partition wall thickness (tr) must be
And outermost cell partition wall thickness (tr) and outer wall thickness (ts)
Between the appropriate ratio range, ie 0.7 ≦ tc / tr ≦ 0.9,
It can be seen that 0.3 ≦ tr / ts ≦ 0.7 exists.

Further, as shown in Tables 1 and 2, depending on the combination of the basic cell partition wall thickness tc and the outer wall thickness ts, not only the partition wall constituting the outermost peripheral cell but also the outermost peripheral cell to the inside of several cells can be increased. By doing so, it is possible to satisfy each performance characteristic within the above-mentioned appropriate ratio range. Although not shown in the examples, when the outermost peripheral cell partition wall was thickened to almost the same thickness as the outer wall thickness of 0.3 mm, the same as in the case where the outer wall thickness was increased to 0.5 mm or more, `` Heat shock resistance '' was used. The tendency was to decrease. This is considered to be due to the fact that when the outermost peripheral cell partition wall thickness is too large, the heat capacity of the outer peripheral portion increases, and the temperature difference between the inside of the carrier and the outer peripheral portion increases.

(Examples 34 to 38, Comparative Example 38) In the same manner as in Example 1 described above, a cordierite-based honeycomb structure (honeycomb carrier) was used. Various honeycomb carriers having a partition wall thickness and an outer wall thickness were produced, and the contact and / or V-shaped connection were built up. The aperture ratio was 83%. Table 3 shows the results.

[0046]

[Table 3]

As is evident from the results in Table 3, the thermal shock resistance was slightly inferior to that of Comparative Example 38 having no built-up, but both the isostatic strength and the corner strength were improved. Further, by combining such a buildup with an increase in the thickness of the outermost peripheral cell partition wall, it was possible to further increase the corner portion strength. In order to investigate the reason, when FEM analysis was performed when isotropic pressure was applied to the outer periphery of the honeycomb structure, it was found that the maximum compressive stress was generated inside the outer wall of the V-shaped connection portion. . Therefore, V
It is considered that the outer wall is easily buckled and broken at the U-shaped connection portion. Also, at the point where the V-shaped connection is made, the contact point between the adjacent rib and the outer wall is close, so that the material flow in the base between the outer wall and the rib is unbalanced, and the flow of the raw material at the V-shaped connecting portion is increased. It is considered to be advantageous for mitigating.

[0048]

As described above, according to the high-strength thin-walled honeycomb structure of the present invention, the isostatic strength and the thermal shock resistance of the thinned honeycomb structure are improved in a well-balanced manner, and the honeycomb structure is improved. Damage of the outer peripheral wall and the corners can be prevented.

[Brief description of the drawings]

FIG. 1 shows an example of a honeycomb structure, and FIG.
Is a perspective view, and (b) is a plan view.

FIG. 2 is a partially enlarged view of a honeycomb structure.

FIG. 3 is an example of a high-strength thin-walled honeycomb structure of the present invention, (a) is a schematic partial cross-sectional view, and (b) is
It is the A section detailed view of (a).

FIG. 4 is a partial cross-sectional explanatory view showing an example of a structure for preventing deformation of a cell partition at an outermost peripheral portion of a honeycomb structure.

FIG. 5 is a partial cross-sectional explanatory view showing an embodiment in which a contact structure is provided on a honeycomb structure.

FIG. 6 is a partial cross-sectional explanatory view showing another embodiment in which a contact structure is applied to a honeycomb structure.

FIG. 7 is a partial cross-sectional explanatory view showing one embodiment in which a V-shaped connection overlay is applied to a honeycomb structure.

FIG. 8 is a graph showing the relationship between the outer wall thickness of the honeycomb structure and the isostatic strength.

FIG. 9 is a graph showing the relationship between the thickness of the outer wall of the honeycomb structure and the thermal shock resistance.

FIG. 10 is a graph showing a relationship between outer wall thickness and outer wall corner strength of the honeycomb structure.

FIG. 11 is a schematic diagram showing a relationship between outermost cell partition wall thickness and outer wall thickness.

FIG. 12 is an explanatory diagram showing an example in which a honeycomb carrier is incorporated in a converter container.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Honeycomb structure, 2 ... Cell partition, 2a ... Outermost cell partition, 2b ... Basic cell partition, 3 ... Cell passage, 4 ... Outer wall,
5: border line between outermost cell partition and basic cell partition, 6: build-up, 7: V-shaped connection part, 8: outermost cell, 9: second cell from outermost cell, 10: partition of outer cell , 11 ... Converter container, 12 ... Ring, 13 ... Honeycomb carrier, 1
4: Buffer member.

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[Procedure amendment]

[Submission date] March 5, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

[0009]

That is, according to the present invention, there is provided a ceramic honeycomb structure having a plurality of cell passages, and a basic cell partition thickness (tc) of a cell partition constituting the honeycomb structure. ) Is tc ≦ 0.11 mm, the outer wall thickness (ts) is ts ≧ 0.2 mm, the opening ratio of the basic cell partition wall thickness portion is 80% or more, and the outermost peripheral cell partition wall thickness (tr) And the basic cell partition wall thickness (t
A high-strength thin-walled honeycomb structure is provided, wherein c) and the outer wall thickness (ts) have the following relationship. 0.7 ≦ tc / tr ≦ 0.9 0.3 ≦ tr / ts ≦ 0.7

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

Further, according to the present invention, there is provided a ceramic honeycomb structure having a plurality of cell passages, wherein a basic cell partition wall thickness of a cell partition wall constituting the honeycomb structure is 0.11 mm or less, and an outer wall thickness is not more than 0.11 mm. Is 0.2 mm or more,
A high-strength thin-walled honeycomb structure is provided, wherein the opening ratio of the basic cell partition wall thickness portion is 80% or more, and a portion where the outermost peripheral cell partition wall and the outer wall of the honeycomb structure contact each other is built up. Is done. Further, according to the present invention, there is provided a ceramic honeycomb structure having a plurality of cell passages, wherein a basic cell partition wall thickness of a cell partition wall constituting the honeycomb structure is 0.11 mm or less, and an outer wall thickness is 0 mm or less. .2mm
The opening ratio of the basic cell partition wall thickness portion is 80%
In addition to the above, there is provided a high-strength thin-walled honeycomb structure characterized in that adjacent partition walls are in contact with the outer wall while the space between the partition walls is narrowed, and at least between the partition walls are built up inside the outer wall. .

Claims (10)

[Claims] 1. A honeycomb structure having a plurality of cell passages, wherein a basic cell partition wall thickness (tc) of a cell partition wall constituting the honeycomb structure is tc ≦ 0.11 mm, and an outer wall thickness (ts) is ts ≧ 0.2 mm, the opening ratio of the basic cell partition wall thickness portion is 80% or more, and the outermost peripheral cell partition wall thickness (tr), the basic cell partition wall thickness (tc), and the outer wall thickness (Ts) having the following relationship: a high-strength thin-walled honeycomb structure. 0.7 ≦ tc / tr ≦ 0.9 0.3 ≦ tr / ts ≦ 0.7 2. Within a range of three cells from the innermost periphery to the innermost periphery of the honeycomb structure, the thickness of the partition walls in the order of 0.7 ≦ tc / tr ≦ 0.9 from the internal cells to the outermost peripheral cells. The high-strength thin-walled honeycomb structure according to claim 1, wherein the honeycomb structure is thickened at a ratio. 3. The high-strength thin-walled honeycomb structure according to claim 1, wherein a portion where the outermost peripheral cell partition wall and the outer wall of the honeycomb structure contact each other is built up. 4. The high-strength thin-walled honeycomb structure according to claim 1, wherein adjacent partition walls are contacted with the outer wall while the space between the partition walls is narrowed, and at least between the partition walls is built up inside the outer wall. 5. A honeycomb structure having a plurality of cell passages, wherein a basic cell partition wall thickness of a cell partition wall constituting the honeycomb structure is 0.11 mm or less, and an outer wall thickness is 0.2 m.
m or more, and the opening ratio of the basic cell partition wall thickness portion is 80
% Of the honeycomb structure, wherein a portion where the outermost peripheral cell partition wall and the outer wall of the honeycomb structure are in contact with each other is built up. 6. A honeycomb structure having a plurality of cell passages, wherein a basic cell partition wall thickness of a cell partition wall constituting the honeycomb structure is 0.11 mm or less, and an outer wall thickness is 0.2 m.
m or more, and the opening ratio of the basic cell partition wall thickness portion is 80
%, And the adjacent partition walls are in contact with the outer wall while the space between the partition walls is narrowing, and at least between the partition walls are built up on the inner side of the outer wall. 7. The honeycomb structure has a square cell shape.
7. A rectangular, rhombic or hexagonal shape.
The high-strength thin-walled honeycomb structure according to any one of the above items. 8. The honeycomb structure according to claim 1, wherein the honeycomb structure is formed of at least one ceramic material selected from the group consisting of cordierite, alumina, mullite, silicon nitride, and silicon carbide. 2. The high-strength thin-walled honeycomb structure according to claim 1. 9. The high-strength thin-walled honeycomb structure according to any one of claims 1 to 8, which is used as a carrier for an automobile exhaust gas purification catalyst. 10. The high-strength thin-walled honeycomb according to any one of claims 1 to 9, wherein a catalyst component is carried on the surface of the cell partition wall, held on the outer peripheral surface of the structure, and incorporated into a catalytic converter. Structure.