JP2012207590A - Converter system for engine exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for making erosion hardly generated at a honeycomb structure even if the thin-walled cordierite-made honeycomb structure is used in a converter and even if the installation position of the converter is close to an engine.SOLUTION: This converter system for engine exhaust gas comprises the honeycomb structure whose cell shape is square and in which a catalyst is held at a partition wall, a case for holding the honeycomb structure, and an exhaust gas introduction pipe which is connected to the case so that the exhaust gas is introduced into the honeycomb structure. When the number of the exhaust gas introduction pipes is one, an angle formed of the exhaust gas introduction pipe and the partition wall of the honeycomb structure when viewing the end face of the honeycomb structure at the front so as to make the cell shape appear is 45±10°, an angle formed of the exhaust gas introduction pipe and the end face of the honeycomb structure is not smaller than 67.5° and not larger than 90°. When the engine is a multicylinder engine and there are plural exhaust gas introduction pipes, an angle formed of a half or more of the exhaust gas introduction pipes and the partition wall of the honeycomb structure when viewing the end face of the honeycomb structure at the front so as to make the cell shape appear is 45±10°, and an angle formed of a half or more of the exhaust gas introduction pipes and the partition wall of the honeycomb structure is not smaller than 67.5° and not larger than 90°.

Description

  The present invention relates to an engine exhaust gas converter system in which erosion hardly occurs in a honeycomb structure.

  With the strengthening of exhaust gas regulations for automobiles, converters having a honeycomb structure carrying a catalyst are being used. This converter is an engine exhaust gas treatment unit disposed at a stage subsequent to an exhaust manifold (also referred to as an exhaust manifold).

  Conventionally, the converter is located behind the exhaust manifold (also referred to as an exhaust manifold) and is located under the floor (a car) slightly away from the engine. Recently, however, the converter is located immediately after the exhaust manifold (directly under the engine). May be provided. In the converter disposed directly under the engine, the catalyst supported on the honeycomb structure is exposed to high-temperature exhaust gas and immediately activated. Therefore, harmful substances discharged immediately after starting the automobile engine are removed. It is possible to reduce.

  The honeycomb structure constituting the converter is usually formed of a plurality of cells whose outer shape is columnar (cylindrical or prismatic) and communicates between the two end faces. The cross-sectional shape (cell shape) perpendicular to the cell length direction (axial direction of the column) is often a quadrangle, and there are other shapes such as a triangle and a hexagon. The honeycomb structure is a porous body made of, for example, cordierite, and the cells are partitioned by porous partition walls having a large number of pores. And a catalyst is carry | supported by this partition.

  In such a honeycomb structure, higher purification performance is required, and for that purpose, the partition walls are preferably thin. This is because if the partition wall on which the catalyst is supported becomes thinner, the heat capacity of the catalyst is reduced and the warm-up characteristic of the purification performance is improved. The desired thickness for the partition walls of the honeycomb structure is about 100 μm or less.

  On the other hand, if a converter having a honeycomb structure is disposed in the rear stage of the exhaust manifold and in the immediate vicinity of the engine (directly under the engine), erosion may occur mainly due to foreign matters mixed in the exhaust gas. This erosion is a phenomenon in which foreign matter that collides with the honeycomb structure at high speed due to a fluid (exhaust gas) wears or beats the end face portion of the honeycomb structure. The foreign matter is, for example, particulate matter having various particle diameters derived from the peeling of the inner surface of the casting exhaust manifold due to oxidation or the welding material used when manufacturing the exhaust manifold. The erosion is considered to occur, for example, when a foreign substance in exhaust gas collides with the partition wall or slides and passes through, and the partition wall is damaged and repeated. In addition, it is considered that a broken piece of the partition wall is generated by damaging the partition wall itself.

  Patent Document 1 can be cited as a prior art document that mentions an erosion countermeasure for a honeycomb structure of a converter disposed directly under an engine.

JP 2002-326035 A

  As described above, it is required to make the partition walls of the honeycomb structure thin (thin walls). When the walls are thin, the breaking strength against external force is reduced, and erosion is likely to occur in the honeycomb structure.

  Also, the closer the converter is located to the engine, the more erosion is likely to occur in the honeycomb structure. This is because the honeycomb structure is exposed to higher-temperature and higher-pressure exhaust gas and receives a greater thermal load such as a thermal shock as compared with the case where the converter is disposed under the floor. This is because it is easily affected by pulsation.

  When erosion occurs in this way, the catalyst is lost in the vicinity of the end face of the honeycomb structure on the side where the exhaust gas enters, resulting in a decrease in catalyst performance. Further, if the honeycomb structure is rolled not only in the vicinity of the end face but also deep inside the honeycomb structure, the honeycomb structure is damaged. Further, when the vicinity of the outer peripheral portion of the honeycomb structure is damaged, the mat member that plays a role of gripping (canning) the honeycomb structure in the (converter) case is exposed. If it does so, a mat member will be scattered by injection of exhaust gas, and the scattered mat may become a foreign substance further and may damage a honeycomb structure. Thus, various problems are caused by erosion.

  The present invention has been made in view of the above circumstances, and is a case where a cordierite honeycomb structure is used for a converter with a thin wall, and the converter is disposed close to the engine. However, it is an object of the present invention to provide means for making erosion unlikely to occur in the honeycomb structure.

  As a result of diligent studies to solve this problem, as for the honeycomb structure having a square cell shape, it is difficult for erosion to occur in the honeycomb structure by specifying the incident angle of the exhaust gas with respect to the partition walls of the honeycomb structure. As a result, the present invention has been completed as shown below.

  That is, according to the present invention, an engine exhaust gas converter system that is disposed directly under an engine and purifies the exhaust gas of the engine, the honeycomb structure in which the cell shape appearing on the end face is a square and the catalyst is supported on the partition walls A body, a case for holding the honeycomb structure, and an exhaust gas introduction pipe connected to the case so that the exhaust gas is introduced into the honeycomb structure. The angle formed by the exhaust gas introduction pipe and the partition walls of the honeycomb structure when the end face of the honeycomb structure is viewed from the front so that the cell shape appears is 45 ± 10 ° (degrees), and the exhaust gas The angle formed between the introduction pipe and the end face of the honeycomb structure is 67.5 ° (degrees) or more and 90 ° (degrees) or less, the engine is multi-cylinder, and the exhaust gas introduction pipes are plural. In some cases, an angle formed by more than half of the exhaust gas introduction pipes and the partition walls of the honeycomb structure when the end face of the honeycomb structure is viewed from the front so that the cell shape appears is 45 ± 10 ° (degrees). In addition, an engine exhaust gas converter system in which an angle formed by more than half of the exhaust gas introduction pipes and the partition walls of the honeycomb structure is 67.5 ° (degrees) or more and 90 ° (degrees) or less is provided. .

  The honeycomb structure in the engine exhaust gas converter system according to the present invention has a columnar body (cylindrical body or prismatic body), and is formed with a plurality of cells communicating between the two end surfaces. The cross-sectional shape (cell shape) perpendicular to the cell length direction (axial direction of the column) is a quadrangle. The cell is defined by a porous partition wall having a large number of pores, and the catalyst is supported on the partition wall.

  In the engine exhaust gas converter system according to the present invention, the case where there is one exhaust gas introduction pipe means that the engine is a single cylinder, and the engine is a multi-cylinder engine, but the exhaust pipe coming out of the engine is a collecting pipe In this case, the exhaust gas is connected to the case as one exhaust gas introduction pipe. That is, the number of exhaust gas introduction pipes is determined by the number of (exhaust gas introduction) pipes connected to the case. The phrase “the converter system is disposed directly under the engine” means that the length of the exhaust gas introduction pipe from the exhaust manifold inlet to the exhaust gas inlet side end face of the honeycomb structure is within 80 cm. When the engine is multi-cylinder and there are a plurality of exhaust gas introduction pipes, the shortest long exhaust gas introduction pipe has a length of 80 cm or less.

  In the engine exhaust gas converter system according to the present invention, there are two required angles. One angle is an angle (also referred to as angle A) formed by the exhaust gas introduction pipe and the partition walls of the honeycomb structure when the end face of the honeycomb structure is viewed from the front so that the cell shape appears. This angle A is also simply referred to as an angle formed by the exhaust gas introduction pipe and the partition walls of the honeycomb structure. The other angle is an angle (also referred to as angle B) formed by the exhaust gas introduction pipe and the end face of the honeycomb structure. This angle B is an angle when the side surface of the honeycomb structure is viewed from the extended line of the end surface of the honeycomb structure, and the end surface is an end surface on the inlet side (inlet end surface). Since the exhaust gas flows in the exhaust gas introduction pipe, the angle formed by the exhaust gas introduction pipe can be rephrased as the angle formed by the exhaust gas. That is, the angle A is an angle formed by the exhaust gas and the partition walls of the honeycomb structure, and the angle B is an angle formed by the exhaust gas and the (inlet) end face of the honeycomb structure.

  In the engine exhaust gas converter system according to the present invention, the requirements for the angles A and B can be divided into a case where there is one exhaust gas introduction pipe and a case where there are a plurality of exhaust gas introduction pipes. I can do it. When there is one exhaust gas introduction pipe, there are one angle A and one B. Further, when there are a plurality of exhaust gas introduction pipes, there are a plurality of angles A and B, respectively. In the engine exhaust gas converter system according to the present invention, when there is one exhaust gas introduction pipe, the angle A is 45 ± 10 °, and the angle B is 67.5 ° or more and 90 ° or less. When there are a plurality of exhaust gas introduction pipes, the angle A of more than half is 45 ± 10 °, and the angle B of more than half is 67.5 ° or more and 90 ° or less.

  The engine exhaust gas converter system according to the present invention is suitably used when the material forming the honeycomb structure is any one selected from the material group consisting of cordierite, mullite, and zeolite.

  The engine exhaust gas converter system according to the present invention is preferably used when the partition wall thickness of the honeycomb structure is 105 μm or less. The lower limit of the partition wall thickness is a practical lower limit of the partition wall thickness, and is about 30 μm. That is, the engine exhaust gas converter system according to the present invention is preferably used when the partition wall thickness of the honeycomb structure is 30 to 105 μm or less. The converter system for engine exhaust gas according to the present invention is particularly preferably used when the partition wall thickness of the honeycomb structure is 30 to 100 μm or less.

  The engine exhaust gas converter system according to the present invention is preferably used when the porosity of the honeycomb structure is 35% or less. The lower limit of the porosity of the honeycomb structure is about 22%. That is, the engine exhaust gas converter system according to the present invention is suitably used when the honeycomb structure has a porosity of 22% or more and 35% or less. The engine exhaust gas converter system according to the present invention is particularly preferably used when the porosity of the honeycomb structure is 25% or more and 35% or less.

  The engine exhaust gas converter system according to the present invention is disposed immediately below the engine. However, when there is one exhaust gas introduction pipe, the end face of the honeycomb structure is faced forward so that the cell shape appears. The angle formed between the exhaust gas introduction pipe and the partition walls of the honeycomb structure is 45 ± 10 °, and the angle formed between the exhaust gas introduction pipe and the end face of the honeycomb structure is 67.5 ° or more and 90 °. When the engine is multi-cylinder and there are a plurality of exhaust gas introduction pipes, more than half of the exhaust gas introduction pipes and honeycomb structure when the end face of the honeycomb structure is viewed from the front so that the cell shape appears. The angle formed by the partition walls is 45 ± 10 °, and the angle formed by more than half of the exhaust gas introduction pipes and the partition walls of the honeycomb structure is 67.5 ° or more and 90 ° or less. D Lojon is unlikely to occur. If the angle is as described above, the incident angle of the exhaust gas and foreign matter on the partition walls of the honeycomb structure becomes small at the time of use, so that the collision energy is small and erosion hardly occurs (the amount of erosion is small). Therefore, it is inferred.

  In a preferred embodiment of the converter system for engine exhaust gas according to the present invention, when the material forming the honeycomb structure is general cordierite (that is, the raw material for forming the honeycomb structure is a cordierite-forming raw material). Therefore, it can be applied to a conventional converter as it is.

  In the preferred embodiment, the converter system for engine exhaust gas according to the present invention is used when the thickness of the partition walls of the honeycomb structure on which the catalyst is supported is as thin as 105 μm or less, so that the heat capacity of the catalyst is reduced and the purification performance is reduced. Excellent warm-up characteristics.

  In the preferred embodiment, the converter system for engine exhaust gas according to the present invention is used when the honeycomb structure has a porosity of 35% or less, which is preferable for supporting a catalyst. Therefore, the converter system can be directly applied to a conventional converter. is there.

It is a figure which shows an exhaust system, and is a perspective view showing one Embodiment (whole structure) of the converter system for engine exhaust gas which concerns on this invention. 1 is a perspective view showing an example of a honeycomb structure that constitutes an engine exhaust gas converter system according to the present invention. FIG. FIG. 3 is a diagram partially showing an embodiment of an engine exhaust gas converter system according to the present invention, and an exhaust gas introduction pipe and a honeycomb structure partition wall when the end face of the honeycomb structure is viewed from the front so that a cell shape appears. It is a top view which shows the angle which is made. FIG. 3 is a diagram partially showing an embodiment of an engine exhaust gas converter system according to the present invention, and an exhaust gas introduction pipe and a honeycomb structure partition wall when the end face of the honeycomb structure is viewed from the front so that a cell shape appears. It is a top view which shows the angle which is made. FIG. 2 is a diagram partially showing an embodiment of an engine exhaust gas converter system according to the present invention, and an exhaust gas introduction pipe and a honeycomb structure when the side surface of the honeycomb structure is viewed from the extension line of the end face of the honeycomb structure. It is a side view which shows the angle which an end surface makes. It is a side view which shows the angle which the exhaust gas introduction pipe | tube and the end surface of a honeycomb structure make in an Example. It is a side view which shows the angle which the exhaust gas introduction pipe | tube and the end surface of a honeycomb structure make in an Example. It is a side view which shows the angle which the exhaust gas introduction pipe | tube and the end surface of a honeycomb structure make in an Example. It is a side view which shows the angle which the exhaust gas introduction pipe | tube and the end surface of a honeycomb structure make in an Example. It is a graph showing the result of an Example, and is a figure which shows the relationship between the angle which the waste gas (introduction pipe) and the partition of a honeycomb structure make, and the amount of erosion. It is a graph showing the result of an Example, and is a figure which shows the relationship between the angle which the waste gas (introduction pipe) and the (inlet) end surface of a honeycomb structure make, and the amount of erosion.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. However, the present invention should not be construed as being limited to these, and those skilled in the art will be able to do so without departing from the scope of the present invention. Various changes, modifications and improvements can be made based on the knowledge. For example, the drawings show preferred embodiments of the present invention, but the present invention is not limited by the modes shown in the drawings or the information shown in the drawings. In practicing or verifying the present invention, means similar to or equivalent to those described in the present specification can be applied, but preferred means are those described below.

  First, the overall configuration of the engine exhaust gas converter system according to the present invention will be described with reference to FIG. A converter system 10 shown in FIG. 1 includes a converter 11 and an exhaust gas introduction pipe 12 (exhaust manifold). Converter 11 includes case 15 and honeycomb structure 1 held by mat 14 therein. In FIG. 1, the converter 11 is drawn so as to be seen through.

  The converter system 10 is an engine exhaust gas converter system that is disposed immediately below the engine 16 (for example, three cylinders) and purifies the exhaust gas of the engine 16. The exhaust gas introduction pipe 12 is connected to each cylinder (cylinder) of a three-cylinder engine 16 on the one hand (for example), and these three pipes are gathered into one so that the exhaust gas discharged from each cylinder of the engine 16 is a honeycomb. It is connected to the case 15 so as to be introduced into the structure 1. The example of the converter system 10 corresponds to the case where the number of pipes connected to the case 15 is 1 (although the engine 16 is multi-cylinder), and thus there is one exhaust gas introduction pipe. In some cases, the three pipes are not assembled into one, but are connected to the case. In this case, the number of pipes connected to the case is 3, so that the engine is multi-cylinder. This corresponds to the case where there are a plurality of exhaust gas introduction pipes.

  The exhaust gas discharged from the engine 16 passes through the converter 11 (honeycomb structure 1 on which the catalyst is supported) via the exhaust gas introduction pipe 12, passes through another exhaust gas treatment device, and a muffler 13 (silencer) (not shown). After that, it is discharged out of the system.

  Next, a honeycomb structure constituting the engine exhaust gas converter system according to the present invention will be described with reference to FIG. The honeycomb structure 1 shown in FIG. 2 has a cylindrical body whose outer shape is composed of two end faces 2a and 2b and a peripheral surface 5 connecting them. In the converter system 10, when the honeycomb structure 1 is gripped by the case 15, the end face 2a is the exhaust gas inlet end face, and the end face 2b is the exhaust gas outlet end face.

  The honeycomb structure 1 is formed with a plurality of cells 3 communicating between the two end faces 2a and 2b. The cross-sectional shape (cell shape) perpendicular to the length direction of the cell 3 (axial direction of the cylindrical honeycomb structure 1) is a quadrangle. In the honeycomb structure 1, cells 3 are partitioned by porous partition walls 4 having a large number of pores, and a catalyst is supported on the partition walls 4.

  Next, with reference to FIG. 3A, FIG. 3B, and FIG. 4, two angles of the engine exhaust gas converter system according to the present invention will be described. 3A and 3B show a mode when the end surface 2a of the honeycomb structure 1 is viewed from the front so that the shape (cell shape) of the cell 3 appears, and the end surface 2a shown there is the entrance It is an end face. In FIGS. 3A and 3B, the case 15 is omitted and not drawn. FIG. 4 shows a mode when the side surface 5 of the honeycomb structure 1 is viewed from the front of the extended line of the end surface 2a of the honeycomb structure 1. FIG. 3A, 3B, and 4, the direction of the exhaust gas introduction pipe 12 is indicated by an arrow.

  The angle A shown in FIGS. 3A and 3B is an angle formed by the exhaust gas introduction pipe 12 and the partition walls 4 of the honeycomb structure 1. In FIG. 3A, the angle A is 45 °, and in FIG. 3B, the angle A is 90 °. The angle B shown in FIG. 4 is an angle formed by the exhaust gas introduction pipe 12 and the end face 2a of the honeycomb structure 1. In FIG. 4, the angle B is 45 °.

  Next, a method for manufacturing the engine exhaust gas converter system according to the present invention will be described. In the engine exhaust gas converter system according to the present invention, when the exhaust gas introduction pipe, the case, and the honeycomb structure are produced, when there is one exhaust gas introduction pipe, the end face of the honeycomb structure is faced to the front so that the cell shape appears. The angle formed between the exhaust gas introduction pipe and the partition walls of the honeycomb structure is 45 ± 10 °, and the angle formed between the exhaust gas introduction pipe and the end face of the honeycomb structure is 67.5 ° or more and 90 ° or less. And Similarly, when the engine is multi-cylinder and there are a plurality of exhaust gas introduction pipes, more than half of the exhaust gas introduction pipes and honeycomb structure when the end face of the honeycomb structure is viewed from the front so that the cell shape appears. The angle formed by the partition walls is 45 ± 10 °, and the angle formed by more than half of the exhaust gas introduction pipes and the partition walls of the honeycomb structure is 67.5 ° or more and 90 ° or less. The honeycomb structure used has a rectangular cell shape. Except for this, the materials, shapes, sizes, etc. used can be produced based on conventionally known means and standards.

  Next, a method of using the engine exhaust gas converter system according to the present invention will be described. The converter system for engine exhaust gas according to the present invention is used by being incorporated into an exhaust system of an automobile (for example). Conventionally, there is no difference from known converter systems.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

(Example 1) [Production of sample (honeycomb structure)] As a raw material, a cordierite-forming raw material composed of talc, kaolin, and alumina was used, and they were prepared at a blending ratio to become cordierite after firing. A binder, a surfactant, and water were added to the raw material and mixed to obtain a clay. Subsequently, the obtained kneaded material was subjected to extrusion molding after firing using a die having a partition wall thickness of 0.09 mm, a cell density of 300 cells / inch ² , and a diameter of 105.7 mm. A molded body was obtained. The obtained honeycomb formed body was cut into a certain length and fired to obtain a honeycomb structure 51 (sample) having a diameter of 105.7 mm, a length of 105.7 mm, and a porosity of 35%. (See FIG. 5A).

  [Construction of test apparatus (corresponding to converter system)] The honeycomb structure 51 (sample) obtained above is wound with an alumina non-expanded mat 64 and is pushed into a metal case 65 (cylinder) for canning. And incorporated into the burner simulation test apparatus 50 (see FIG. 5A). The burner simulation test apparatus 50 is a test apparatus that can supply a gas having a constant temperature and flow rate to a sample. The gas used is LNG. Further, in the burner simulation test apparatus 50, in order to simulate the erosion phenomenon, a foreign substance input pipe 67 for introducing pseudo foreign substances is connected to the exhaust gas pipe 62 (corresponding to the exhaust gas introduction pipe) immediately before the sample.

  [Test conditions] When the sample was canned, the direction of the sample was set such that the exhaust gas hit the partition wall of the sample (honeycomb structure 51) in the direction of 45 ° (angle A, not shown in FIG. 5A). . Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas is 67.5 ° (angle B, see FIG. 5A) with respect to the inlet end surface 52a of the sample (honeycomb structure 51). I tried to win. Then, SiC abrasive grains were used as the pseudo foreign matters, and a total amount of 15 g was introduced from the foreign matter introduction pipe 67 so that the mass flow rate was 34 g / sec. As the SiC abrasive grains, those having a particle diameter of 50 μm close to the size of the foreign matter generated in an actual engine were selected. The exhaust gas temperature of a burner (not shown) was 900 ° C.

  [Test result (calculation of erosion amount)] The volume of the sample (honeycomb structure 51) cut was defined as the erosion amount. Since it is difficult to directly measure the volume from which the honeycomb structure 51 is cut, the amount of erosion was determined as follows. That is, first, before starting the test, the sample volume is obtained from the measurement result of the sample dry weight and the measurement result of the diameter and length of the sample. Then, the bulk density of the sample is obtained by (sample dry weight) / (sample volume (calculated value)). Then, after the test, the sample dry weight is measured in the same manner. Then, the scraped volume is obtained by (sample dry weight before test−sample dry weight after test) / (sample bulk density), and this is defined as the erosion amount. The results are shown in Table 1.

  (Example 2) When the sample was canned, the direction of the sample was set so that the exhaust gas hit the partition wall of the sample (honeycomb structure 51) in the direction of 35 ° (angle A, not shown). Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas hits the inlet end surface 52a of the sample (honeycomb structure 51) at 67.5 ° (angle B, not shown). I did it. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  (Example 3) When the sample is canned, the direction of the sample is set so that the exhaust gas strikes the partition wall of the sample (honeycomb structure 51) in the direction of 45 ° (angle A, not shown in FIG. 5B). did. Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas strikes the inlet end surface 52a of the sample (honeycomb structure 51) at 90 ° (angle B, see FIG. 5B). I made it. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  (Example 4) When the sample was canned, the direction of the sample was set so that the exhaust gas hit the partition wall of the sample (honeycomb structure 51) in the direction of 45 ° (angle A, not shown). Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas hits the inlet end surface 52a of the sample (honeycomb structure 51) at 79 ° (angle B, not shown). did. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  (Comparative Example 1) When the sample was canned, the direction of the sample was set so that the exhaust gas hit the partition wall of the sample (honeycomb structure 51) in the direction of 30 ° (angle A, not shown). Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas hits the inlet end surface 52a of the sample (honeycomb structure 51) at 67.5 ° (angle B, not shown). I did it. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  (Comparative Example 2) When the sample was canned, the direction of the sample was set so that the exhaust gas hit the partition wall of the sample (honeycomb structure 51) in the direction of 25 ° (angle A, not shown). Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas hits the inlet end surface 52a of the sample (honeycomb structure 51) at 67.5 ° (angle B, not shown). I did it. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  (Comparative Example 3) The orientation of the sample was set so that the exhaust gas hit the partition wall of the sample (honeycomb structure 51) in the direction of 15 ° (angle A, not shown) when canning the sample. Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas hits the inlet end surface 52a of the sample (honeycomb structure 51) at 67.5 ° (angle B, not shown). I did it. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  (Comparative Example 4) When the sample is canned, the orientation of the sample is set so that the exhaust gas strikes the partition wall of the sample (honeycomb structure 51) in the direction of 0 ° (angle A, parallel, not shown). did. Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas hits the inlet end surface 52a of the sample (honeycomb structure 51) at 67.5 ° (angle B, not shown). I did it. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  (Comparative Example 5) The orientation of the sample was set so that when the sample was canned, the exhaust gas hit the partition wall of the sample (honeycomb structure 51) in the direction of 45 ° (angle A, not shown). Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas strikes the inlet end surface 52a of the sample (honeycomb structure 51) at 56 ° (angle B, not shown). did. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  (Comparative Example 6) When the sample was canned, the direction of the sample was set so that the exhaust gas hit the partition wall of the sample (honeycomb structure 51) in the direction of 45 ° (angle A, not shown in FIG. 5C). did. Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas strikes the inlet end surface 52a of the sample (honeycomb structure 51) at 45 ° (angle B, see FIG. 5C). I made it. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  (Comparative Example 7) When the sample is canned, the direction of the sample is set so that the exhaust gas hits the partition wall of the sample (honeycomb structure 51) in the direction of 45 ° (angle A, not shown in FIG. 5D). did. Further, the shape of the jig for attaching the sample to the burner simulation test apparatus 50 is devised so that the exhaust gas strikes the inlet end surface 52a of the sample (honeycomb structure 51) at 34 ° (angle B, see FIG. 5D). I made it. Otherwise, the test was performed under the same conditions as in Example 1 to determine the amount of erosion. The results are shown in Table 1.

  [Consideration] In actual automobiles and vehicles, it is estimated that the amount of erosion varies depending on complicated factors such as exhaust gas temperature, exhaust amount, exhaust manifold material, and applied catalyst amount. Therefore, it is difficult to determine the reference value of the erosion amount in the evaluation using the burner simulation test apparatus. Therefore, during the test, when the angle A at which the exhaust gas hits the partition walls of the honeycomb structure and the angle B with respect to the inlet end face are changed, the angle at which the erosion amount starts to change abruptly is determined as the desired angle in actual use. Thought. Under this concept, the angle (angle) formed between the exhaust gas and the partition wall of the honeycomb structure 51 (sample) when the exhaust gas hits the inlet end surface 52a of the honeycomb structure 51 (sample) at 67.5 ° (angle B). The relationship between A) and the amount of erosion is summarized in FIG. Further, the angle (angle B) formed by the exhaust gas and the inlet end surface 52a of the honeycomb structure 51 (sample) when the exhaust gas hits the partition wall of the honeycomb structure 51 (sample) in the direction of 45 ° (angle A). The relationship between the amount of erosion and the amount of erosion is summarized in FIG.

  Table 1 and FIGS. 6 and 7 show the following. That is, from Examples 1 and 2 and Comparative Examples 1 to 4, when the angle A at which the exhaust gas hits the partition walls of the honeycomb structure becomes smaller than 35 °, the amount of erosion increases rapidly. This is because, when the angle at which the exhaust gas hits the partition walls of the honeycomb structure becomes small, the velocity component perpendicular to the partition walls increases when a foreign substance riding on the exhaust gas collides with the partition walls. This is estimated to be because it becomes large and is easily destroyed. Similarly, from Examples 1, 3, 4 and Comparative Examples 5 to 7, it can be seen that when the angle B at which the exhaust gas hits the inlet end face becomes smaller than 67.5 °, the amount of erosion increases rapidly. Similarly, when the angle B at which the exhaust gas hits the inlet end face of the honeycomb structure becomes small, when a foreign substance riding on the exhaust gas collides with the partition, a velocity component perpendicular to the partition increases. It is presumed that the impact force received by the partition wall increases and is easily broken.

  The converter system for engine exhaust gas according to the present invention can be suitably used for purifying gas discharged from an automobile engine.

DESCRIPTION OF SYMBOLS 1,51: Honeycomb structure 2a, 2b, 52a: End surface 3: Cell 4: Partition 5: Peripheral surface 10: Converter system 11: Converter 12: Exhaust gas introduction pipe 13: Muffler 14, 64: Mat 15, 65: Case 16 : Engine 50: Burner simulation test device 62: Exhaust gas pipe 67: Foreign material input pipe

Claims (4)

An engine exhaust gas converter system that is disposed directly under an engine and purifies engine exhaust gas,
A honeycomb structure in which a cell shape appearing on an end face is a quadrangle, and a catalyst is supported on partition walls;
A case for holding the honeycomb structure;
An exhaust gas introduction pipe connected to the case so that the exhaust gas is introduced into the honeycomb structure,
When there is one exhaust gas introduction pipe, the angle formed by the exhaust gas introduction pipe and the partition walls of the honeycomb structure when the end face of the honeycomb structure is viewed from the front so that the cell shape appears is 45 ±. The angle formed by the exhaust gas introduction pipe and the end face of the honeycomb structure is 67.5 ° or more and 90 ° or less,
When the engine is multi-cylinder and there are a plurality of exhaust gas introduction pipes, more than half of the exhaust gas introduction pipes and the honeycomb structure when the end face of the honeycomb structure is viewed from the front so that the cell shape appears. The angle formed by the partition walls is 45 ± 10 °, and the angle formed by more than half of the exhaust gas introduction pipes and the partition walls of the honeycomb structure is 67.5 ° or more and 90 ° or less. Converter system.   2. The engine exhaust gas converter system according to claim 1, wherein a material forming the honeycomb structure is any one selected from a material group consisting of cordierite, mullite, and zeolite.   The engine exhaust gas converter system according to claim 1 or 2, wherein a thickness of the partition wall of the honeycomb structure is 105 µm or less.   The engine exhaust gas converter system according to any one of claims 1 to 3, wherein the honeycomb structure has a porosity of 35% or less.

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