JP2007107495A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine which is hardly influenced by the deterioration of an exhaust purifying catalyst easily even at a time of cold start of the internal combustion engine, and keeping exhaust emission control performance high. <P>SOLUTION: This exhaust emission control device is provided with the exhaust purifying catalyst 20 arranged in an engine exhaust passage, and exhaust gas flows in the exhaust purifying catalyst from an upstream side end part and flows out of the same from a downstream side end part. Moreover, the exhaust emission control device is provided with a grinding means 30 grinding the upstream side end part of the exhaust purifying catalyst by moving on the upstream side end part of the exhaust purifying catalyst dyeing operation of the internal combustion engine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine.

Generally, an exhaust purification catalyst for purifying exhaust gas is provided in the exhaust passage of the internal combustion engine, and the exhaust purification catalyst is in exhaust gas flowing into the exhaust purification catalyst (hereinafter referred to as “inflow exhaust gas”). Harmful components such as hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO _x ) and the like are oxidized or reduced for purification.

  The ability to purify harmful components by such an exhaust purification catalyst is not always constant, such as lead components, phosphorus components and sulfur components in the inflowing exhaust gas (hereinafter referred to as “catalyst poisoning components”). Is reduced by being stored in the exhaust purification catalyst. As described above, when the purification capacity of the exhaust purification catalyst is reduced, that is, when the exhaust purification catalyst is deteriorated, harmful components in the inflowing exhaust gas are not sufficiently purified, and harmful components are also contained in the exhaust gas flowing out from the exhaust purification catalyst. Will be included.

  For this reason, the exhaust purification catalyst described in Patent Document 1 is provided with a trap layer that collects catalyst poisoning components in the vicinity of the upstream end face of the exhaust purification catalyst. By providing the trap layer on the exhaust upstream side of the exhaust purification catalyst in this manner, the catalyst poisoning component in the exhaust gas discharged from the engine body is collected in the trap layer. Is less likely to flow in, so that the deterioration of the exhaust purification catalyst can be reduced.

JP 2002-172329 A

  By the way, the reduction of the purification ability of the exhaust purification catalyst, that is, the deterioration of the exhaust purification catalyst gradually proceeds from the upstream end of the exhaust purification catalyst. This is because catalyst poisoning components in the exhaust gas flowing into the exhaust purification catalyst are occluded from the upstream end of the exhaust purification catalyst, and only those not occluded at the upstream end are occluded on the downstream side. It is.

  On the other hand, when the internal combustion engine is cold-started, the temperature of the exhaust purification catalyst is low, and the exhaust purification catalyst is heated by the exhaust gas discharged from the engine body. The temperature rise of the exhaust purification catalyst gradually proceeds from the upstream end of the exhaust purification catalyst toward the downstream side. Therefore, when the internal combustion engine is cold started, the temperature in the vicinity of the upstream end of the exhaust purification catalyst tends to be high. In order for the exhaust purification catalyst to exhibit its purification capability, the temperature of the exhaust purification catalyst needs to be somewhat high, so that the temperature of the portion other than the portion near the upstream end of the exhaust purification catalyst becomes high Exhaust gas purification is mainly performed in the vicinity of the upstream end.

  Here, if the portion in the vicinity of the upstream end of the exhaust purification catalyst has deteriorated, at the time of the cold start of the internal combustion engine, the exhaust gas is exhausted due to deterioration even though the temperature of only the portion in the vicinity of the upstream end is first increased. The gas will not be purified. That is, when the exhaust purification catalyst deteriorates, the purification performance of the exhaust purification catalyst particularly at the time of cold start is lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust purification device for an internal combustion engine that is hardly affected by the deterioration of the exhaust purification catalyst even during a cold start of the internal combustion engine and that maintains its exhaust purification performance at a high level. .

In order to solve the above-mentioned problems, in the first invention, an exhaust purification catalyst is provided in the engine exhaust passage, and exhaust gas flows into the exhaust purification catalyst from its upstream side end, and the downstream side end. In the exhaust gas purification apparatus for an internal combustion engine that flows out from the section, there is provided a grinding means for grinding the upstream end portion of the exhaust purification catalyst by moving on the upstream end portion of the exhaust purification catalyst during operation of the internal combustion engine.
According to the first aspect, since the grinding means for grinding the upstream end portion of the exhaust purification catalyst is provided, the upstream end portion of the deteriorated exhaust purification catalyst can be gradually ground. As a result, the deterioration of the upstream end of the exhaust purification catalyst, which is a particular problem during cold start of the internal combustion engine, is suppressed.

According to a second aspect, in the first aspect, the exhaust purification catalyst is disposed such that its upstream end is positioned vertically above the downstream end, and the grinding member flows into the exhaust purification catalyst. The exhaust gas moves on the upstream end of the exhaust purification catalyst by the flow of exhaust gas or the vibration of the vehicle on which the exhaust purification catalyst is mounted.
According to the second invention, since the grinding member is moved by the flow of exhaust gas or the vibration of the vehicle, it is not necessary to separately provide power for moving the grinding member.

  According to a third invention, in the second invention, the weight of the grinding member is such that the grinding member does not fly up from the upstream end of the exhaust purification catalyst even when the exhaust gas flows. It is such a weight that it moves along.

  According to a fourth aspect, in the third aspect, the weight of the grinding member is determined according to the displacement per cylinder.

  In a fifth invention, in any one of the first to fourth inventions, the grinding member is made of a material whose wear resistance is higher than the wear resistance of the material constituting the exhaust purification catalyst.

  In a sixth invention, in any one of the first to fifth inventions, the grinding member has a protruding portion that protrudes toward the outside of the grinding member, and the protruding portion has a pointed tip.

  In a seventh invention, in any one of the first to sixth inventions, the exhaust purification catalyst is formed in a honeycomb shape, and the size of the grinding member is the same as that of the exhaust purification catalyst. The size is such that it does not completely enter the exhaust flow passage.

According to an eighth invention, in any one of the first to seventh inventions, the exhaust purification catalyst is located at a position of a predetermined length from the downstream end face of the exhaust purification catalyst toward the upstream side. A partition member made of a material having higher wear resistance than the wear resistance of the grinding member is provided between the upstream catalyst portion and the downstream catalyst portion.
Here, the “predetermined length” is, for example, the length of the exhaust purification catalyst necessary for purifying harmful components in the exhaust gas, and is equal to the “limit length” in an embodiment described later.

  According to a ninth invention, in any one of the first to eighth inventions, a recess capable of at least partially accommodating the grinding member is provided at an upstream end of the exhaust purification catalyst.

  According to the present invention, since the grinding means for grinding the upstream end portion of the exhaust purification catalyst is provided, the deterioration of the upstream end portion of the exhaust purification catalyst, which is particularly problematic during cold start, is suppressed. Even at the time of starting, the exhaust purification performance is maintained high.

  Hereinafter, an exhaust emission control device of the present invention will be described in detail with reference to the drawings. FIG. 1 is a view showing an entire internal combustion engine in which the exhaust emission control device of the present invention is mounted.

  Referring to FIG. 1, 1 is an engine body, 2 is a cylinder block, 3 is a piston that reciprocates in the cylinder block 2, 4 is a cylinder head fixed on the cylinder block 2, and 5 is a piston 3 and a cylinder head 4. A combustion chamber formed therebetween, 6 is an intake valve, 7 is an intake port, 8 is an exhaust valve, and 9 is an exhaust port. As shown in FIG. 1, a spark plug 10 is arranged at the center of the inner wall surface of the cylinder head 4, and a fuel injection valve 11 is arranged around the inner wall surface of the cylinder head 4. A cavity 12 extending from the lower side of the fuel injection valve 11 to the lower side of the spark plug 10 is formed on the top surface of the piston 3.

  The intake port 7 of each cylinder is connected to a surge tank 14 via a corresponding intake branch pipe 13, and the surge tank 14 is connected to an air cleaner (not shown) via an intake duct 15 and an air flow meter 16. A throttle valve 18 driven by a step motor 17 is disposed in the intake duct 15. On the other hand, the exhaust port 9 of each cylinder is connected to an exhaust manifold 19, and the exhaust manifold 19 is connected to a casing 21 containing an upstream side exhaust purification catalyst 20. An outlet of the casing 21 is connected to a casing 24 containing a downstream side exhaust purification catalyst 23 via an exhaust pipe 22.

  FIGS. 2A and 2B show a front view and a cross-sectional side view of the upstream side exhaust purification catalyst 20. As shown in FIGS. 2A and 2B, the upstream side exhaust purification catalyst 20 has a honeycomb structure, and has a plurality of exhaust flow passages 20a extending in parallel with each other between the upstream end and the downstream end. The exhaust gas flows along these exhaust flow passages 20a with hardly passing through the partition walls 20b between the exhaust flow passages 20a. That is, the exhaust gas flows in the upstream side exhaust purification catalyst 20 in the direction of the axis A of the upstream side exhaust purification catalyst 20.

  The partition wall 20b of the upstream side exhaust purification catalyst 20 is formed by supporting a carrier made of alumina or the like as a porous material on a base made of cordierite or the like. Exhaust gas flowing into the upstream side exhaust purification catalyst 20 (hereinafter referred to as “inflowing exhaust gas”) passes through the pores formed on the carrier such as alumina and in the carrier when passing through the exhaust flow passage 20a. Flowing. A catalytic noble metal such as platinum (Pt) is supported on the surface of the carrier and on the surface of the pores, and harmful components in the exhaust gas when the exhaust gas passes on the surface of the carrier and on the surface of the pores ( For example, hydrocarbon (HC), carbon monoxide (CO), etc.) are oxidized and purified by the oxidizing action of the catalyst noble metal.

  When the upstream side exhaust purification catalyst 20 is used as, for example, a three-way catalyst, cerium (Ce) or the like is supported as an oxygen storage agent on a carrier made of alumina or the like in addition to platinum. The oxygen storage agent is oxygen in the exhaust gas when the air-fuel ratio of the inflowing exhaust gas (the ratio of the air and fuel supplied to the upstream exhaust passage, the combustion chamber 5 and the intake passage) is lean. When the air-fuel ratio in the inflowing exhaust gas is almost the stoichiometric air-fuel ratio or rich, the stored oxygen is released.

Alternatively, when the upstream side exhaust purification catalyst 20 is used as a NO _x storage reduction catalyst, potassium (K), barium (Ba) or the like is supported on the carrier as the NO _x storage agent in addition to platinum. _The NO _X storage agent, the air-fuel ratio of the inflowing exhaust gas is occluded NO _X in the exhaust gas when the lean, disengaging the NO _X when the air-fuel ratio of the inflowing exhaust gas is occluded when approximately stoichiometric or rich . Thus, NO _X is in the exhaust gas discharged stored in the NO _X absorbent from the upstream exhaust purification catalyst 20 NO _X even air-fuel ratio is a lean contained in the exhaust gas flowing into the exhaust gas together becomes not almost contain, hydrocarbons nO _X which are caused to leave from _the nO _X storage agent when the air-fuel ratio of the inflowing exhaust gas is substantially stoichiometric or rich is contained in the inflowing exhaust gas (HC) and a single Reduced and purified by carbon oxide (CO).

By the way, the exhaust gas flowing into the upstream side exhaust purification catalyst 20 contains lead component (Pb), phosphorus component (P) and sulfur component (S) in addition to HC, CO and NO _x in a small amount. . The lead component and the phosphorus component are mainly contained in the lubricating oil, and a part of the lubricating oil is contained in the exhaust gas discharged from the engine body 1 by burning in the combustion chamber 5. On the other hand, the sulfur component is contained in the fuel in a small amount, and is contained in the exhaust gas discharged from the engine body 1 by the combustion of the fuel in the combustion chamber 5.

These lead, phosphorus, and sulfur components contained in the inflowing exhaust gas lower the purification ability of the upstream side exhaust purification catalyst 20 and degrade the upstream side exhaust purification catalyst 20. That is, part of both the lead and phosphorus components in the inflowing exhaust gas is adsorbed on the pore surface of the carrier. When both the lead and phosphorus components are adsorbed on the pore surface of the carrier in this manner, the catalyst noble metal, oxygen storage agent, NO _X storage agent, etc. supported on the support are covered with these lead / phosphorus components. Further, when the adsorption of these lead / phosphorus components on the pore surface of the carrier proceeds, the pores of the carrier are blocked by these lead / phosphorus components. With this or pores or catalyst noble metal is covered is blocked by a lead-phosphorus component, the catalyst noble metal inflow exhaust gas is supported on a carrier, to contact the oxygen storage agent and _the NO _X storage agent Therefore, the exhaust purification ability of the upstream side exhaust purification catalyst 20 is reduced. A part of the sulfur component in the inflowing exhaust gas is occluded in the NO _X absorbent. Sulfur component in the NO _X absorbent is made to decrease _the NO _X storage ability of the occluded _the NO _X storage agent, thus the exhaust purification performance by the upstream exhaust purification catalyst 20 is made to decrease.

  FIG. 3 shows the length from the upstream end face of the upstream side exhaust purification catalyst after the exhaust gas has passed through the upstream side exhaust purification catalyst over a certain period, that is, the position in the direction of the axis A of the upstream side exhaust purification catalyst. It is a figure which shows the adsorption amount of the phosphorus to the upstream side exhaust purification catalyst according to this. In FIG. 3, the x-axis is the length from the upstream end surface of the upstream side exhaust purification catalyst (the plane on which the upstream end surface of the partition wall is located), and the y-axis is the amount of phosphorus adsorbed per unit length of the upstream side exhaust purification catalyst. Is shown.

  As can be seen from FIG. 3, after the exhaust gas is circulated through the upstream side exhaust purification catalyst, a large amount of phosphorus is adsorbed in the vicinity of the upstream end portion of the upstream side exhaust purification catalyst, and toward the downstream side. The amount of adsorption gradually decreases. There is a similar tendency for lead and sulfur. Therefore, all the components of lead, phosphorus and sulfur (hereinafter referred to as “catalyst poisoning components”) are abundant in the vicinity of the upstream end of the upstream side exhaust purification catalyst. Occluded and the amount of occlusion decreases toward the downstream side. This is because the catalyst poisoning component in the inflowing exhaust gas is occluded from the upstream side of the exhaust purification catalyst, and only what is not occluded at the upstream end is occluded at the downstream side. It is. Therefore, the degree of deterioration due to the catalyst poisoning component is large on the upstream side of the upstream side exhaust purification catalyst, and decreases toward the downstream side.

  On the other hand, as can be seen from FIG. 1, the upstream side exhaust purification catalyst 20 is disposed immediately downstream of the exhaust manifold 19, and the temperature is raised by the exhaust gas discharged from the engine body 1 even when the temperature is low. It is easy to be done. For this reason, the upstream side exhaust purification catalyst 20 is arranged mainly for the purpose of purifying exhaust gas when the internal combustion engine is cold-started.

  However, at the time of cold start of the internal combustion engine, first, the temperature in the vicinity of the upstream end of the upstream side exhaust purification catalyst 20 is raised by the high-temperature exhaust gas discharged from the engine body 1, and thereafter the upstream side exhaust purification catalyst is gradually increased. The temperature on the downstream side of 20 is increased. Therefore, immediately after the internal combustion engine is cold-started, the exhaust gas discharged from the engine body 1 until the downstream portion is heated after the temperature in the vicinity of the upstream end of the upstream exhaust purification catalyst 20 is raised. This purification is basically performed only by the portion in the vicinity of the upstream end portion of the upstream side exhaust purification catalyst 20.

  Here, as described above, the degree of deterioration due to the catalyst poisoning component is large in the vicinity of the upstream end portion of the upstream side exhaust purification catalyst. Therefore, even when the degree of deterioration of the entire upstream side exhaust purification catalyst is small, there is a case where the degree of deterioration in the vicinity of the upstream end is large. In such a case, the purification capability by the portion in the vicinity of the upstream end of the upstream side exhaust purification catalyst 20 becomes low. For this reason, in the period when only the temperature in the vicinity of the upstream end of the upstream side exhaust purification catalyst 20 is raised during the cold start of the internal combustion engine, the upstream side exhaust purification catalyst 20 sufficiently purifies the inflowing exhaust gas. I can't.

  Therefore, in the embodiment of the present invention, a grinding member for grinding the upstream end of the exhaust purification catalyst during operation of the internal combustion engine is used. Hereinafter, the grinding member will be described in detail.

  FIG. 4 is a sectional view of the upstream side exhaust purification catalyst 20 and the casing 21 containing the upstream side exhaust purification catalyst 20 of the present invention. In the present embodiment, the upstream side exhaust purification catalyst 20 is arranged substantially vertically so that its upstream end is positioned vertically above the downstream end.

  In the present embodiment, the grinding member 30 is disposed on the upstream end portion of the upstream side exhaust purification catalyst 20. The grinding member 30 is made of a material having higher wear resistance than the material constituting the upstream side exhaust purification catalyst 20. In the present embodiment, as described above, the upstream side exhaust purification catalyst 20 is formed of cordierite, and the grinding member 30 is formed of a material having higher wear resistance, such as stainless steel (SUS316, SUS310, etc.). .

  In this embodiment, the shape of the grinding member 30 is such that it has one or more protrusions extending outward from the grinding member 30, and these protrusions have a pointed tip. Composed. Specific examples of the shape of the grinding member 30 are shown in FIGS. In the example shown in FIG. 5 (a), the shape of the grinding member 30 is a cube or a rectangular parallelepiped, and in the example shown in FIG. 5 (b), the side of the grinding member 30 is trapezoidal. That is, it is configured to have a truncated pyramid shape. In the example shown in FIG. 5C, the shape of the grinding member 30 is a triangular prism shape, and in the example shown in FIG. Is a columnar shape with a star-shaped cross section, and in the example shown in FIG. 5D, the shape of the grinding member 30 is a columnar shape. However, the shape of the grinding member 30 is not limited to the five examples shown in FIGS. 5 (a) to 5 (e), and the protrusion is configured to extend outward and have a sharp tip. As long as it has at least one part, it may have any shape.

  Further, in the present embodiment, the grinding member 30 has a size that prevents the grinding member 30 from completely entering the exhaust flow passage 20a, that is, cannot pass through each cell defining the exhaust flow passage 20a. It is made such a size. For example, in the case of the grinding member 30 shown in FIG. 5A, the cross section of each side surface of the cube is larger than the cross section of each cell.

  The grinding member 30 configured in this way moves on the upstream end of the upstream exhaust purification catalyst 20 by the flow of exhaust gas passing through the upstream exhaust purification catalyst 20 or by the vibration of the vehicle on which the exhaust purification catalyst is mounted. . As the grinding member 30 moves, friction occurs between the upstream end of the upstream side exhaust purification catalyst 20 and the grinding member 30. Since the grinding member 30 is made of a material having higher wear resistance than the material constituting the upstream side exhaust purification catalyst 20 as described above, the grinding member 30 is disposed between the upstream end of the upstream side exhaust purification catalyst 20 and the grinding member 30. When friction occurs, the grinding member 30 is hardly ground and only the upstream end of the upstream side exhaust purification catalyst 20 is gradually ground. In particular, since the grinding member 30 has a shape having a plurality of protrusions with sharp tips, it is easy to grind the upstream end of the upstream exhaust purification catalyst 20. Further, since the grinding member 30 is sized so as not to completely enter the exhaust flow passage 20a, the exhaust flow passage of the upstream side exhaust purification catalyst 20 even if the grinding member 30 receives the flow of exhaust gas. It does not pass through 20a.

  As described above, the upstream end portion of the upstream side exhaust purification catalyst 20 is gradually ground, thereby reducing the exhaust gas purification capability when the internal combustion engine is cold-started due to the deterioration of the upstream side exhaust purification catalyst 20. Can be prevented. That is, as described above, the deterioration of the upstream side exhaust purification catalyst 20 is large in the vicinity of the upstream end portion, but according to the present embodiment, the portion of the deteriorated upstream side exhaust purification catalyst 20 in the vicinity of the upstream end portion is It is gradually scraped off by the grinding member 30. For this reason, even if the upstream side exhaust purification catalyst 20 is used for a certain period of time, the degree of deterioration in the vicinity of the upstream end portion of the upstream side exhaust purification catalyst 20 remains relatively small. As described above, the exhaust gas purification capacity at the time of cold start of the internal combustion engine depends on the degree of deterioration in the vicinity of the upstream end portion of the upstream side exhaust purification catalyst 20, and therefore, the upstream side of the upstream side exhaust purification catalyst 20 According to the present invention in which the degree of deterioration in the vicinity of the end portion is maintained to be relatively small, the exhaust gas purification capability at the time of cold start of the internal combustion engine is maintained at a relatively high level.

  In the present embodiment, the weight of the grinding member 30 is such that the grinding member 30 moves in contact with the upstream end of the upstream exhaust purification catalyst 20 by the flow of exhaust gas flowing into the upstream exhaust purification catalyst 20. Weight. That is, since a part of the exhaust gas flowing into the upstream side exhaust purification catalyst 20 hits the upstream end face of the partition wall 20b of the upstream side exhaust purification catalyst 20, the exhaust gas flows on the upstream end portion of the upstream side exhaust purification catalyst 20. Disturbance occurs, but if the weight of the grinding member 30 is too light, the grinding member 30 is swung up from the upstream end of the upstream side exhaust purification catalyst 20 due to this disturbance, and moves while contacting the upstream end. Will not be able to. On the other hand, if the weight of the grinding member 30 is too heavy, the grinding member on the upstream end of the upstream side exhaust purification catalyst 20 also due to the disturbance of the exhaust gas flow generated on the upstream end of the upstream side exhaust purification catalyst 20. It becomes impossible to move 30. Here, in the present embodiment, the weight of the grinding member 30 is such that the grinding member 30 moves while being in contact with the upstream end, and therefore the grinding member 30 is at the upstream end of the upstream side exhaust purification catalyst 20. It is prevented that the grinding member 30 is swung up by the turbulence generated on the part, or the grinding member 30 hardly moves on the upstream end of the upstream side exhaust purification catalyst 20.

  In particular, in this embodiment, the weight of the grinding member 30 is set according to the displacement per cylinder. This will be described in detail below.

  FIG. 6 is a diagram showing a time transition of the flow rate of exhaust gas passing through the upstream side exhaust purification catalyst 20 (hereinafter referred to as “exhaust flow rate”) during one cycle of the internal combustion engine. As can be seen from the figure, the exhaust flow rate fluctuates up and down in accordance with the opening and closing of the exhaust valve 8 and causes so-called exhaust pulsation. In particular, in the example shown in FIG. 6, the exhaust flow rate is increased by first opening the exhaust valve 8 corresponding to the first cylinder, and then the exhaust flow rate is decreased by closing the exhaust valve 8. Thereafter, the exhaust valve 8 opens in the order of the third cylinder, the fourth cylinder, and the second cylinder, so that the exhaust flow rate similarly increases and decreases.

  Since the grinding member 30 tends to rise from the upstream end of the upstream exhaust purification catalyst 20 as the exhaust flow rate passing through the upstream exhaust purification catalyst 20 increases, the exhaust flow rate passing through the upstream exhaust purification catalyst 20 is maximized. When the exhaust gas is at the maximum, that is, when the exhaust gas having the maximum exhaust flow rate (the one-dot chain line in the figure) passes, it is most likely to soar. Therefore, the weight of the grinding member 30 needs to be a weight that does not rise even when the exhaust gas having the maximum exhaust flow rate passes, and needs to be set according to the maximum exhaust flow rate.

  Here, the maximum exhaust flow rate changes according to the exhaust amount per cylinder, and the maximum exhaust flow rate increases as the exhaust amount per cylinder increases. Therefore, in the present embodiment, the weight of the grinding member 30 is set according to the displacement per cylinder, and is set in proportion to the displacement per cylinder, for example.

For example, as shown in FIG. 7A, in a four-cylinder internal combustion engine having a total displacement of 1000 cm ³ , the displacement per cylinder is 250 cm ^{3. In} this case, the grinding member 30 serves as the upstream side exhaust purification catalyst 20. Assuming that the weight that moves while being in contact with the upstream end of the engine is 10 g, a four-cylinder internal combustion engine having a total displacement of 1000 cm ³ as shown in FIG. Also for the internal combustion engine provided with two communicating upstream exhaust purification catalysts 20, the weight of the grinding member 30 is set to 10 g. Further, as shown in FIG. 7C, in a 4-cylinder internal combustion engine having a total displacement of 2000 cm ³ , the displacement per cylinder is 500 cm ³ and the weight of the grinding member 30 is 20 g. Further, as shown in FIG. 7D, in a 6-cylinder internal combustion engine having a total displacement of 2000 cm ³ , the displacement per cylinder is 333 cm ³ and the weight of the grinding member 30 is about 13.3 g. .

  FIG. 8 is a diagram showing the relationship between the travel distance of a vehicle equipped with an internal combustion engine and the exhaust gas purification ability of the upstream side exhaust purification catalyst 20. The solid line in the figure indicates that the grinding member 30 is inserted on the upstream end portion of the upstream side exhaust purification catalyst 20 from the initial stage when the upstream side exhaust purification catalyst 20 is completed or when the upstream side exhaust purification catalyst 20 is assembled to the vehicle. The broken line in the figure indicates the case where the grinding member 30 is not inserted, and the alternate long and short dash line in the figure indicates the case where the grinding member 30 is inserted at time A.

  As can be seen from the figure, when the grinding member 30 is inserted from the beginning (solid line), the exhaust gas purification capability by the upstream side exhaust purification catalyst 20 is always higher than when the grinding member 30 is not inserted (dashed line). It is expensive. This is because, as described above, when the grinding member 30 is inserted, the portion of the upstream side exhaust purification catalyst 20 deteriorated by the grinding member 30 is gradually scraped off. On the other hand, if the grinding member 30 is inserted on the upstream end portion of the upstream side exhaust purification catalyst 20 at a time A when the vehicle has traveled a certain distance from the time when the upstream side exhaust purification catalyst 20 is assembled, the upstream side deteriorated. Since the portion in the vicinity of the upstream end portion of the side exhaust purification catalyst 20 is scraped off, the exhaust purification capability of the upstream side exhaust purification catalyst 20 is recovered as shown by the one-dot chain line in FIG. However, even if the exhaust purification capability of the upstream side exhaust purification catalyst 20 is recovered by inserting the grinding member 30 at time A, the exhaust purification capability of the upstream side exhaust purification catalyst 20 is shown in FIG. Thus, it does not recover beyond the exhaust gas purification capability when the grinding member 30 is inserted from the beginning. Therefore, if the grinding member 30 is inserted at the time A, the exhaust purification capability is lower than the case where the grinding member 30 is inserted from the beginning at least before the time A, and the exhaust purification capability is also from the initial stage after the timing A. Exhaust gas purification capacity when the grinding member 30 is inserted is not exceeded. Therefore, in this embodiment, the grinding member 30 is inserted from the beginning.

  In the above-described embodiment, the upstream side exhaust purification catalyst 20 is disposed substantially vertically so that the upstream end thereof is positioned vertically upward, but the upstream side exhaust purification catalyst 20 is not disposed vertically. Also good. For example, the upstream side exhaust purification catalyst 20 may be disposed such that its upstream end is positioned vertically above the downstream end, that is, inclined. However, in this case, the grinding member 30 tends to roll down to the position vertically below the position on the upstream end of the upstream side exhaust purification catalyst 20, so that the exhaust passing through the upstream side exhaust purification catalyst 20 is exhausted. The weight of the grinding member 30 must be set more carefully so that the grinding member 30 moves over the upstream end of the upstream side exhaust purification catalyst 20 by the gas flow and uniformly grinds the upstream end. Don't be. Alternatively, the upstream side exhaust purification catalyst 20 may be arranged so that its axis is horizontal. In this case, the weight of the grinding member 30 must be set more carefully.

  Further, the shape of the grinding member 30 is not limited to the shape having the protruding portion with the sharp tip as shown in FIG. 5, and may be any shape. Therefore, for example, the shape of the grinding member 30 may be spherical as shown in FIG. 9A, or may be a hemispherical cylinder with both ends as shown in FIG. 9B. As shown in FIG. 9, when the outer shape of the grinding member 30 is made smooth, the upstream end of the upstream side exhaust purification catalyst 20 has a pointed protrusion as shown in FIG. It becomes difficult to grind compared with the case where the shape grinding member 30 is used. Therefore, for example, when the upstream end of the upstream exhaust purification catalyst 20 is easily ground due to the relationship between the material constituting the upstream exhaust purification catalyst 20 and the material constituting the grinding member 30, the shape of the grinding member 30 is changed. If the upstream end of the upstream side exhaust purification catalyst 20 is difficult to be ground, the shape of the grinding member 30 is changed to the shape shown in FIG. The amount of grinding at the upstream end of the side exhaust purification catalyst 20 can be optimally controlled.

  Further, the grinding member 30 moving on the upstream end of the upstream side exhaust purification catalyst 20 contacts and rubs against the casing 21 containing the upstream side exhaust purification catalyst 20. For this reason, when the casing 21 is made of a material having a lower wear resistance than the wear resistance of the grinding member 30 or a material having the same degree of wear resistance, the side surface of the casing 21 is ground by the grinding member 30 and the casing 21 has holes. May open. For this reason, in this embodiment, it is preferable that the casing 21 is made of a material having higher wear resistance than the wear resistance of the grinding member 30. Alternatively, when the casing 21 is made of a material having the same wear resistance as that of the grinding member 30, the upstream end of the upstream side exhaust purification catalyst 20 on the inner surface of the casing 21 as shown in FIG. A reinforcing member 21a is provided at a position upstream of the position. As a result, the reinforcing member 21a is ground by the movement of the grinding member 30, but the casing 21 is not ground, so that the casing 21 is prevented from opening a hole.

  In the above description, the case where the grinding member 30 is used for the upstream side exhaust purification catalyst 20 has been described, but it is also possible to use a grinding member for the downstream side exhaust purification catalyst 23.

  Next, an exhaust emission control device according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 10 is an example of the relationship between the length from the upstream end face of the upstream side exhaust purification catalyst and the purification rate of hydrocarbons (HC) in the exhaust gas passing through the portion of the upstream side exhaust purification catalyst located at the length. FIG. Circles in the figure indicate that the flow rate of hydrocarbons flowing into the upstream side exhaust purification catalyst is 10 g / s. Squares in the figure indicate that the flow rate of hydrocarbons into the upstream side exhaust purification catalyst is 20 g / s. Each case is shown.

  As can be seen from FIG. 10, HC in the exhaust gas flowing into the upstream side exhaust purification catalyst is mainly purified in the vicinity of the upstream end portion of the upstream side exhaust purification catalyst. In particular, in the example shown in FIG. 10, when the exhaust gas flowing into the upstream side exhaust purification catalyst passes through a position where the length from the upstream end face is 50 mm, HC is purified by nearly 90%, and the position at 80 mm At the time of passing through HC, HC has been purified by nearly 100%. Therefore, the upstream exhaust purification catalyst shown in FIG. 10 can sufficiently purify the inflowing exhaust gas if the upstream exhaust purification catalyst has a total length of about 80 mm or more, and conversely, the upstream exhaust purification catalyst has a full length of It can be seen that if it is shorter than 80 mm, HC or the like remains in the exhaust gas flowing out from the upstream side exhaust purification catalyst. That is, it can be seen that a certain length of the upstream side exhaust purification catalyst is required in order to sufficiently purify harmful components in the exhaust gas by the upstream side exhaust purification catalyst.

  Therefore, in the present embodiment, even if the upstream end of the upstream side exhaust purification catalyst 20 is ground by the grinding member 30, the upstream side exhaust purification catalyst 20 having a certain length (hereinafter referred to as “limit length”). The part of remains. Here, the limit length is a length that allows the upstream side exhaust purification catalyst 20 to sufficiently purify harmful components in the exhaust gas if the upstream side exhaust purification catalyst 20 of the length remains. For example, in the case of an exhaust purification catalyst showing a tendency as shown in FIG.

  FIG. 11 is a sectional view of the upstream side exhaust purification catalyst of the present invention and its casing according to the second embodiment. As shown in FIG. 11, in the present embodiment, the downstream end face of the upstream side exhaust purification catalyst 20 remains so that the upstream side exhaust purification catalyst 20 part of the limit length remains without being scraped off by the grinding member 30. A partition member 35 is provided at a position of the limit length L toward the exhaust upstream side. In other words, the upstream side exhaust purification catalyst 20 is divided into the upstream side catalyst portion 201 and the downstream side catalyst portion 202 at the position of the limit length L from the downstream end face of the upstream side exhaust purification catalyst 20 toward the upstream side. A partition member 35 is provided between the upstream catalyst portion 201 and the downstream catalyst portion 202. The partition member 35 extends on a plane perpendicular to the axis of the upstream side exhaust purification catalyst 20.

  FIG. 12A is a plan view of the partition member 35. As can be seen from FIG. 12A, the partition member 35 includes an outer frame member 36 having substantially the same radius as the outer peripheral portion of the upstream side exhaust purification catalyst 20, and a transverse member extending perpendicularly to each other within the outer frame member 36. 37. In the embodiment shown in FIG. 12A, the partition member 35 includes two transverse members 37 extending perpendicularly to each other. The outer frame member 36 and the transverse member 37 constituting the partition member 35 are preferably aligned with the partition wall 20b of the upstream side exhaust purification catalyst 20 to prevent the partition member 35 from becoming exhaust resistance, but are aligned with the partition wall 20b. Without extending, it may extend across the exhaust flow passage 20a.

  The partition member 35 is formed of a material whose wear resistance is higher than the wear resistance of the grinding member 30. Accordingly, when the upstream side exhaust purification catalyst 20 portion located upstream of the partition member 35, that is, the upstream catalyst portion 201 is scraped by the grinding member 30, the partition member 35 comes into contact with the grinding member 30. The grinding member 30 is ground by friction between the partition member 35 and the grinding member 30. Thus, when the grinding member 30 is ground by contact with the partition member 35 and is reduced to such a size that it can completely enter the exhaust flow passage 20a, the grinding member 30 passes through the exhaust flow passage 20a by the flow of exhaust gas. To the downstream side of the upstream side exhaust purification catalyst 20. For this reason, the upstream side exhaust purification catalyst 20 is prevented from being further ground by the grinding member 30, so that the upstream side exhaust purification catalyst 20 part of the limit length, that is, the downstream side catalyst part 202 remains. Thereby, even if the upstream side exhaust purification catalyst 20 is ground by the grinding member 30, it is maintained so that harmful components in the exhaust gas can be sufficiently purified.

  In the above-described embodiment, the partition member 35 includes the two transverse members 37 extending perpendicularly to each other, but the shape of the partition member 35 may be other shapes. For example, the partition member 35 may include three or more cross members 37. In the example shown in FIG. 12B, a set of five cross members 37a extending in parallel with each other, and this set of cross members. Another set of five cross members 37b extending perpendicular to the cross member 37a.

  Further, the cross-sectional shape of the partition member 35 may be any shape, but as shown in FIG. 12C, which is a cross-sectional view of the partition member 35 viewed from the line cc in FIG. A shape having a plurality of corners facing the exhaust upstream side is preferable. By setting the cross-sectional shape of the partition member 35 to such a shape, the grinding member 30 is easily worn, and the grinding member 30 can be quickly removed from the upstream end of the upstream side exhaust purification catalyst 20. become.

  Further, in the above embodiment, the partition member 35 is provided so that the upstream side exhaust purification catalyst 20 part of the limit length remains even when the grinding member 30 is ground. The amount of the upstream side exhaust purification catalyst 20 of the limit length may be left by adjusting the amount. That is, by appropriately selecting the material and the shape of the grinding member 30, the limit length is reached when the vehicle on which the upstream side exhaust purification catalyst 20 is mounted travels a target travel distance (for example, 100,000 km or 70,000 km). The portion of the upstream side exhaust purification catalyst 20 may remain.

  Next, an exhaust emission control device according to a third embodiment of the present invention will be described with reference to FIGS. 13 is a cross-sectional side view of the upstream side exhaust purification catalyst 40 and its casing 21 according to the third embodiment, and FIG. 14 is a cross section of the upstream side exhaust purification catalyst 40 and the casing 21 as seen from line XIV-XIV in FIG. It is a top view.

  By the way, when a grinding member is inserted into a new upstream exhaust purification catalyst, the upstream exhaust purification catalyst is not deteriorated, that is, when it exhibits sufficient exhaust purification capability, the upstream of the upstream exhaust purification catalyst. Grinding of the side end is started. In order to avoid such a situation, the upstream end of the upstream side exhaust purification catalyst is less likely to be ground by the grinding member 30 over a certain period after the use of the new upstream side exhaust purification catalyst is started. It is necessary to.

  Therefore, in the upstream side exhaust purification catalyst 40 of the present embodiment, as shown in FIG. 13, a recess 41 is provided at the upstream end portion thereof. The recess 41 is disposed on the axis A of the upstream side exhaust purification catalyst 40 and has a size capable of accommodating the grinding member 30 at least partially. Specifically, the depth D of the recess 41 in the axial direction of the upstream side exhaust purification catalyst 40 is the flow of exhaust gas passing through the upstream side exhaust purification catalyst 40 when the grinding member 30 is accommodated in the recess 41 or The depth of the recess 41 in the direction perpendicular to the axis A of the upstream exhaust purification catalyst 40 is set to such a depth that the grinding member 30 does not jump out of the recess 41 due to the vibration of the vehicle on which the upstream exhaust purification catalyst 40 is mounted. The width W is sized such that the grinding member 30 is completely contained within the width. More specifically, the upstream side exhaust purification catalyst 40 is configured such that a space having a depth D and a width W corresponding to the recess 41 is formed in a portion near the upstream end of the upstream side exhaust purification catalyst 40. The upstream portion of the partition wall 40b is removed.

  In the upstream side exhaust purification catalyst 40 configured in this manner, the grinding member 30 is accommodated in the recess 41 when the use is started from a new state. The grinding member 30 accommodated in the recess 41 cannot jump out of the recess 41 even if it receives the flow of exhaust gas, and therefore moves only in the recess 41. For this reason, the grinding member 30 cannot move over the upstream end portion of the upstream side exhaust purification catalyst 40, and therefore the upstream end portion of the upstream side exhaust purification catalyst 40 is basically ground by the grinding member 30. Not. However, since the grinding member 30 receives the flow of the exhaust gas and moves in the recess 41, friction occurs between the grinding member 30 and the partition wall 40b that defines the recess 41, and thus the partition wall that defines the recess 41. 40b is gradually ground. In particular, the grinding member 30 gradually grinds the partition walls that define the side surfaces of the recesses 41 among the partition walls 40 b that define the recesses 41 (that is, the partition walls positioned so as to surround the grinding member 30).

  For this reason, when the use is started from a new state, the partition wall 40b that defines the side surface of the recess 41 is gradually ground by the grinding member 30, so that the recess 41 gradually becomes lateral (that is, the upstream side exhaust purification catalyst). 40) (in a direction perpendicular to the axis A of 40), the step defining the recess 41 becomes smooth. As a result, the entire upstream end of the upstream side exhaust purification catalyst 40 becomes smooth, and the grinding member 30 can freely move over the entire upstream end of the upstream side exhaust purification catalyst 40. Thus, after the grinding member 30 can freely move over the entire upstream end of the upstream side exhaust purification catalyst 40, the upstream end of the upstream side exhaust purification catalyst 40 by the grinding member 30. The whole grinding starts.

  Thus, in the present embodiment, the recess 41 is provided at the upstream end of the upstream side exhaust purification catalyst 40, and the grinding member 30 is accommodated in the recess 41 when the upstream side exhaust purification catalyst 40 starts to be used from a new state. By doing so, it is possible to delay the start of grinding of the entire upstream end of the upstream side exhaust purification catalyst 40 by the grinding member 30. Thereby, since the grinding of the entire upstream end by the grinding member 30 is started after the upstream exhaust purification catalyst 20 has deteriorated to some extent, the upstream side from the time when the upstream exhaust purification catalyst 20 has hardly deteriorated. The start of grinding of the entire upstream end of the exhaust purification catalyst 40 is prevented.

  It should be noted that the deterioration rate of the portion in the vicinity of the upstream end portion of the upstream side exhaust purification catalyst 40 varies depending on the internal combustion engine and the vehicle on which the internal combustion engine is mounted. Therefore, in this embodiment, the grinding start timing of the entire upstream end of the upstream side exhaust purification catalyst 40 is adjusted in accordance with the deterioration rate of the upstream side exhaust purification catalyst 40.

  More specifically, the deterioration due to sulfur among the deterioration of the upstream side exhaust purification catalyst 40 makes the air-fuel ratio of the exhaust gas flowing into the upstream side exhaust purification catalyst 40 substantially the stoichiometric air-fuel ratio or rich, and the upstream side exhaust purification catalyst 40. Therefore, the most serious problem among the deterioration of the upstream side exhaust purification catalyst 40 is deterioration due to lead or phosphorus contained in the exhaust gas. The deterioration of the upstream side exhaust purification catalyst 40 due to lead or phosphorus is mainly caused by combustion of lubricating oil of the internal combustion engine and inclusion of these components in the exhaust gas. That is, the deterioration of the upstream side exhaust purification catalyst 40 is promoted with the consumption of the lubricating oil. Therefore, the deterioration rate of the upstream end portion of the upstream side exhaust purification catalyst 40 changes according to the consumption rate of the lubricating oil, and the deterioration rate of the upstream end portion of the upstream side exhaust purification catalyst 40 increases as the consumption rate of the lubricating oil increases. fast.

  On the other hand, if the width W of the concave portion 41 of the upstream side exhaust purification catalyst 40 is small in the new state, the grinding member 30 will not be much in the concave portion 41 even if it receives the flow of exhaust gas at the beginning of use of the upstream side exhaust purification catalyst 40. It cannot move, and the grinding amount of the partition wall 40b per unit time by the grinding member 30 is relatively small. Further, the amount of the partition 40b that must be ground by the grinding member 30 before the recess 41 is smoothed is large. For this reason, it takes time until the grinding of the entire upstream end of the upstream side exhaust purification catalyst 40 is started by the grinding member 30 after the use of the upstream side exhaust purification catalyst 40 is started in a new state. On the contrary, if the width W of the concave portion 41 of the upstream side exhaust purification catalyst 40 is large in a new state, the grinding member 30 moves greatly in the concave portion 41 when receiving an exhaust gas flow from the beginning of use of the upstream side exhaust purification catalyst 40. Therefore, the grinding amount of the partition 40b per unit time by the grinding member 30 is relatively large. Further, the amount of the partition 40b that must be ground by the grinding member 30 before the recess 41 is smoothed is small. For this reason, grinding of the entire upstream end of the upstream side exhaust purification catalyst 40 is started by the grinding member 30 relatively early after the use of the upstream side exhaust purification catalyst 40 is started in a new state.

  Therefore, in the present embodiment, an exhaust purification catalyst having a large width W of the recess 41 is used for an internal combustion engine with a high consumption rate of lubricating oil because the deterioration rate of the upstream portion of the upstream exhaust purification catalyst 40 is fast. ing. On the other hand, for an internal combustion engine with a slow consumption rate of lubricating oil, an exhaust purification catalyst having a small width W of the recess 41 is used because the deterioration rate of the upstream portion of the upstream exhaust purification catalyst 40 is slow. Thus, after the upstream portion of the upstream side exhaust purification catalyst 40 is deteriorated to some extent, the portion near the upstream end portion of the upstream side exhaust purification catalyst 40 is ground by the grinding member 30.

  The exhaust purification catalyst of the third embodiment can be combined with the exhaust purification catalyst of the second embodiment.

In the above description, the NO _X and sulfur components are described as being stored in the NO _X storage agent or the like, but the term “occlusion” is “absorption” (for example, sulfate for a sulfur component). forms that accumulate in) and "adsorption" etc. (e.g., used to include both concepts can) to adsorb in the form of ₂ such as SO and SO _X if sulfur component. Further, the term “detachment” from the NO _X storage agent or the like is also used to include both concepts of “release” corresponding to “absorption” and “desorption” corresponding to “adsorption”.

It is a figure which shows the whole internal combustion engine by which the exhaust gas purification apparatus of this invention is mounted. It is a figure which shows the structure of a catalytic converter. It is a figure which shows the adsorption amount of the phosphorus to the upstream side exhaust purification catalyst according to the position of the axial direction of an upstream side exhaust purification catalyst after distribute | circulating exhaust gas to an upstream side exhaust purification catalyst over a fixed period. It is sectional drawing of the upstream side exhaust purification catalyst of this invention, and its casing. It is a figure which shows the specific example of the shape of a grinding member. It is a figure which shows the time transition of the flow volume of the exhaust gas which passes an upstream exhaust-gas purification catalyst. It is a figure for demonstrating the relationship between the kind of internal combustion engine, and the weight of a grinding member. It is a figure which shows the relationship between the travel distance of the vehicle carrying an internal combustion engine, and the exhaust gas purification ability of the exhaust gas by an upstream side exhaust purification catalyst. It is a figure similar to FIG. 5 which shows the specific example of the shape of a grinding member. It is a figure which shows the example of the relationship between the length from the upstream edge part of an upstream side exhaust purification catalyst, and the purification rate of the hydrocarbon in the exhaust gas which passes through the part of the upstream side exhaust purification catalyst located in the said length. It is sectional drawing of the upstream side exhaust purification catalyst of 2nd embodiment, and its casing. It is the top view and sectional drawing of a partition member. It is a cross-sectional side view of the upstream side exhaust purification catalyst and its casing of a third embodiment. FIG. 14 is a cross-sectional plan view of the upstream side exhaust purification catalyst and casing 21 as seen from line XIV-XIV in FIG. 13.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine body 19 Exhaust manifold 20, 40 Upstream exhaust purification catalyst 20a, 40a Exhaust flow passage 20b, 40b Partition 21 Casing 22 Exhaust pipe 23 Downstream exhaust purification catalyst 24 Casing 30 Grinding member 35 Partition member 41 Recess

Claims (9)

In an exhaust gas purification apparatus for an internal combustion engine, comprising an exhaust gas purification catalyst disposed in an engine exhaust passage, wherein exhaust gas flows into the exhaust gas purification catalyst from its upstream end and flows out from its downstream end.
An exhaust gas purification apparatus for an internal combustion engine, comprising grinding means for grinding the upstream end portion of the exhaust purification catalyst by moving on the upstream end portion of the exhaust purification catalyst during operation of the internal combustion engine.   The exhaust purification catalyst is arranged such that its upstream end is positioned vertically above the downstream end, and the grinding member is mounted with the flow of exhaust gas flowing into the exhaust purification catalyst or the exhaust purification catalyst 2. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the exhaust gas purification apparatus moves on the upstream end of the exhaust gas purification catalyst due to the vibration of the vehicle.   The weight of the grinding member is such a weight that the grinding member moves along the upstream end portion without rising from the upstream end portion of the exhaust purification catalyst even when receiving the flow of the exhaust gas. Item 3. An exhaust emission control device for an internal combustion engine according to Item 2.   The exhaust gas purification apparatus for an internal combustion engine according to claim 3, wherein the weight of the grinding member is determined according to an exhaust amount per cylinder.   The exhaust gas purification apparatus according to any one of claims 1 to 4, wherein the grinding member is made of a material whose wear resistance is higher than the wear resistance of the material constituting the exhaust gas purification catalyst.   The exhaust purification device for an internal combustion engine according to any one of claims 1 to 5, wherein the grinding member has a protruding portion that protrudes toward the outside of the grinding member, and the protruding portion has a pointed tip. .   The exhaust purification catalyst is formed in a honeycomb shape, and the size of the grinding member is such that the grinding member does not completely enter the exhaust flow passage constituting the honeycomb of the exhaust purification catalyst. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 6.   The exhaust purification catalyst is divided into an upstream catalyst portion and a downstream catalyst portion at a position of a predetermined length from the downstream end face of the exhaust purification catalyst toward the upstream side, and the upstream catalyst portion and the downstream catalyst portion are separated from each other. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 7, wherein a partition member made of a material having higher wear resistance than the wear resistance of the grinding member is provided.   9. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein a recess capable of accommodating at least a part of the grinding member is provided at an upstream end portion of the exhaust gas purification catalyst.

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