JP6204617B2 - Exhaust purification device - Google Patents

Description

  The present invention relates to an exhaust purification device in which a catalyst is provided in an exhaust passage.

  As an apparatus for purifying exhaust gas discharged from an internal combustion engine, an exhaust purification apparatus in which a catalyst is disposed in an exhaust passage is known. In such an exhaust purification device, there is a problem that the flow velocity distribution of the exhaust gas flowing into the catalyst is biased, for example, the flow velocity at the outer peripheral portion is lower than the flow velocity at the central portion in the exhaust flow path.

  In order to solve such a problem, by providing an inhibiting member that inhibits part of the flow of the exhaust gas flowing out from the catalyst on the downstream side of the catalyst, the deviation of the flow velocity distribution of the exhaust gas flowing into the catalyst is reduced. An exhaust emission control device has been proposed (see Patent Document 1).

JP 2014-122596 A

  The configuration described in Patent Document 1 described above is premised on a catalyst whose shape when viewed from the central axis direction is a perfect circle, and is a circular recess that is reduced in size by a small size when viewed from the central axis direction. It obstructs part of the flow of exhaust gas. However, an inhibitor member that is particularly suitable for a catalyst having a shape whose longitudinal direction is defined when viewed from the central axis direction, such as an elliptical shape, has not been considered.

  In one aspect of the present invention, in an exhaust gas purification apparatus including a catalyst having a shape whose longitudinal direction is defined when viewed from the central axis direction, it is desirable to increase the effect of reducing the deviation in the flow velocity distribution of exhaust gas flowing into the catalyst. .

  One aspect of the present invention is an exhaust emission control device, which is provided in an exhaust passage and is provided with an exhaust gas purification catalyst, and is provided in the exhaust passage and inhibits part of the exhaust gas flow to flow into the catalyst. And an inhibiting member that reduces unevenness in the flow velocity distribution of exhaust gas. The inhibiting member has a recessed portion that is recessed on the upstream side of the exhaust passage and a support portion that supports the recessed portion at a predetermined position with respect to the catalyst, and inhibits a part of the flow of exhaust gas at the recessed portion. The concave portion has a shape in which the longitudinal direction is defined when viewed from the central axis direction of the concave portion, and the first concave portion center line that is the central line along the longitudinal direction and the center perpendicular to the first concave portion center line. This is a shape that is line symmetric even if any of the second recess center lines that are lines is the axis of symmetry. The catalyst has a shape in which a longitudinal direction is defined when viewed from the central axis direction of the catalyst, and a first catalyst center line that is a center line along the longitudinal direction and a center orthogonal to the first catalyst center line The shape is symmetrical with respect to any of the second catalyst center lines, which are lines. The inhibiting member is disposed in a direction in which the first recess center line and the first catalyst center line are orthogonal to each other with respect to the catalyst.

  According to such a configuration, it is possible to increase the effect of reducing the deviation of the flow velocity distribution of the exhaust gas flowing into the catalyst having a shape whose longitudinal direction is defined when viewed from the central axis direction. The term “orthogonal” as used in the above configuration does not require a strict angle, but may be in a range where an effect can be obtained.

  In the above configuration, the concave portion may have a shape in which the width of the concave portion at a position along the first concave portion center line becomes larger as it is closer to the center when viewed from the central axis direction of the concave portion. According to such a configuration, for example, compared with a case where the width of the recess at a position along the first recess center line is constant, the effect of reducing the unevenness in the flow velocity distribution of the exhaust gas flowing into the catalyst is increased. be able to.

In the above-described configuration, the catalyst may have a shape in which the width of the catalyst at a position along the first catalyst center line is larger as it is closer to the center when viewed from the central axis direction of the catalyst.
In the above-described configuration, the length of the recess along the first recess center line may be shorter than the length of the catalyst along the second catalyst center line in the inhibition member. According to such a configuration, a gap is formed at the end of the catalyst in the direction along the second catalyst center line so that the flow of exhaust gas is not hindered by the recess. For this reason, it is possible to suppress an increase in pressure loss due to the provision of the blocking member while reducing the uneven flow velocity distribution of the exhaust gas flowing into the catalyst.

  In the above configuration, the inhibition member may be disposed on the downstream side of the exhaust flow path with respect to the catalyst. According to such a configuration, there is no need to provide any member on the upstream side for reducing the uneven flow velocity distribution of the exhaust gas flowing into the catalyst, or the necessity thereof is low. Therefore, it is possible to reduce the uneven flow velocity distribution of the exhaust gas flowing into the catalyst while suppressing the temperature drop of the exhaust gas flowing into the catalyst.

  In the above configuration, the inhibition member may be disposed upstream of the catalyst in the exhaust flow path. According to such a configuration, since the concave portion of the inhibition member directly acts on the exhaust gas before flowing into the catalyst, it is possible to easily adjust the flow velocity distribution of the exhaust gas flowing into the catalyst.

It is sectional drawing which shows the structure of the exhaust gas purification apparatus of 1st Embodiment. It is II-II sectional drawing in FIG. FIG. 3A is a perspective view of the inhibition member of the first embodiment as viewed from the catalyst side, and FIG. 3B is a perspective view of the inhibition member as viewed from the side opposite to the catalyst side. 4A is a rear view of the obstruction member of the first embodiment, FIG. 4B is a sectional view taken along the line IVB-IVB in FIG. 4A, and FIG. 4C is a sectional view taken along the line IVC-IVC in FIG. It is sectional drawing which shows the structure of the exhaust gas purification apparatus of 2nd Embodiment.

  DESCRIPTION OF SYMBOLS 100,200 ... Exhaust gas purification apparatus, 2 ... Flow path member, 2A ... 1st pipe part, 2B ... 2nd pipe part, 2C ... 3rd pipe part, 2D ... 4th pipe part, 2E ... 5th Tube portion, 3 ... catalyst, 4,5,6,7 ... center line, 10 ... inhibiting member, 11 ... recessed portion, 12 ... support portion, 111 ... end portion, 112 ... bottom surface, 113 ... rise surface, A ... center axis.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
An exhaust purification device 100 shown in FIG. 1 is a device for purifying exhaust gas discharged from an internal combustion engine (for example, a gasoline engine) of an automobile. The arrows in FIG. 1 indicate the direction in which the exhaust gas flows.

The exhaust purification device 100 includes a flow path member 2, a catalyst 3, and an inhibition member 10.
The flow path member 2 forms a part of an exhaust flow path for guiding the exhaust gas discharged from the internal combustion engine to the outside of the automobile. The flow path member 2 includes, in order from the upstream side, the first tube portion 2A, the second tube portion 2B, the third tube portion 2C, the fourth tube portion 2D, and the fifth tube portion 2E. . These are classifications for convenience of explanation. The division of the parts constituting the flow path member 2 is not particularly limited.

The first tube portion 2A is a straight circular tube portion.
The third tube portion 2C is a linear elliptic tube portion provided coaxially with the central axis A of the first tube portion 2A. The third tube portion 2C has at least an inner diameter along the major axis of the ellipse to accommodate the elliptical columnar catalyst 3 having a size that cannot be accommodated in the first tube portion 2A. It is formed larger than. The first tube portion 2A and the third tube portion 2C are gently connected by a second tube portion 2B that forms an enlarged flow passage for gradually expanding the inner diameter of the exhaust flow passage.

  The fifth tube portion 2E is a straight circular tube portion provided coaxially with the central axis A of the third tube portion 2C. The inner diameter of the fifth pipe portion 2E is smaller than at least the inner diameter along the major axis of the ellipse of the third pipe portion 2C. In this example, the first tube portion 2A and the fifth tube portion 2E have the same inner diameter. The 3rd pipe part 2C and the 5th pipe part 2E are gently connected by 4th pipe part 2D which forms the diameter-reduction channel for reducing the internal diameter of an exhaust flow path gradually.

That is, the flow path member 2 forms an exhaust flow path having an enlarged diameter flow path on the upstream side of the catalyst 3 and a reduced diameter flow path on the downstream side of the catalyst 3.
The catalyst 3 is a ceramic carrier that supports a noble metal such as platinum, palladium, or rhodium. The carrier is a filter having an elliptical columnar shape, and is configured such that the exhaust gas flowing into the inflow surface (upstream side end surface) flows out from the outflow surface (downstream side end surface). HC, CO, NOx, etc. in the exhaust gas are purified by oxidation reaction or oxidation / reduction reaction when passing through the catalyst 3. The catalyst 3 is provided coaxially with the central axis A of the third pipe portion 2C inside the third pipe portion 2C. As shown in FIG. 2, the catalyst 3 has an elliptical shape when viewed from the direction of the central axis A, and has a center line (long axis) 4 along the longitudinal direction and a short direction perpendicular to the center line 4. The shape is axisymmetric even if any of the center line (short axis) 5 along the axis is a symmetric axis.

The inhibition member 10 is provided only on the downstream side of the upstream side and the downstream side of the catalyst 3 in the exhaust passage.
As shown in FIGS. 3A-3B and 4A-4C, the inhibition member 10 includes a recess 11 and two support portions 12.

  The recess 11 is a container-like portion in which no through hole is formed, and the upstream side of the exhaust passage (the side facing the outflow surface of the catalyst 3) is recessed. The concave portion 11 is provided coaxially with the central axis A of the catalyst 3 inside the third pipe portion 2C. The concave portion 11 has an elliptical shape when viewed from the direction of the center axis A, and a center line (long axis) 6 along the longitudinal direction and a center line along the short direction perpendicular to the center line 6. (Short Axis) 7 is a shape that is line symmetric regardless of which of 7 is the axis of symmetry. An end 111 that is bent so as to rise to the upstream side of the exhaust passage is formed at the outer edge of the recess 11. In other words, a rising surface 113 that rises with respect to the bottom surface 112 is formed at the outer edge portion of the end portion 111 on the surface that forms the recess 11. The rising surface 113 has a smaller angle with respect to the straight line along the central axis A than the bottom surface 112.

  The two support portions 12 are portions in which a belt-like plate is bent in an L shape, and are provided at both ends of the recess 11 in the longitudinal direction. The outer surface on the tip side of the bent portion of the support portion 12 is a curved surface corresponding to the shape of the inner peripheral surface of the third tube portion 2C (a circle whose shape viewed from the direction of the central axis A is a part of an ellipse). Arc-shaped) and joined to the inner peripheral surface of the third pipe portion 2C by welding or the like. In the present embodiment, the L-shaped support portion 12 whose surface direction is parallel to the central axis A is exemplified, but the present invention is not limited to this, and for example, intersects the central axis A (for example, orthogonal). The structure in which the surface was formed in direction may be sufficient.

  The support portion 12 has a function of supporting the concave portion 11 at a predetermined position with respect to the catalyst 3 (in this embodiment, a position facing the center of the outflow surface of the catalyst 3). Specifically, as shown in FIG. 1, the recess 11 is arranged such that the position along the central axis A is at a predetermined distance from the outflow surface of the catalyst 3. In addition, as shown in FIG. 2, the recess 11 is oriented so that the center lines (center line 6 and center line 4) along the respective longitudinal directions are perpendicular to the catalyst 3 when viewed from the direction of the center axis A. Is arranged. In particular, in this embodiment, when viewed from the direction of the central axis A, the center line 7 along the short direction of the recess 11 overlaps the center line 4 along the longitudinal direction of the catalyst 3, and extends along the longitudinal direction of the recess 11. The recess 11 is arranged so that the center line 6 overlaps the center line 5 along the short direction of the catalyst 3.

  Further, the length (major axis) of the recess 11 along the center line 6 is shorter than the length (minor axis) of the catalyst 3 along the center line 5. That is, the recess 11 is not large enough to cover the entire outflow surface of the catalyst 3 as viewed from the direction of the central axis A, but large enough to cover a part thereof. Further, on both outer sides of the recess 11 in the direction along the center line 6, a gap is formed in which the flow of exhaust gas that passes through the end of the catalyst 3 in the direction along the center line 5 is not inhibited by the recess 11. In addition, the recessed part 11 and the support part 12 which comprise the obstruction member 10 are divisions for convenience of explanation, and the division of the parts which comprise the obstruction member 10 is not specifically limited. For example, the obstruction member 10 is manufactured by pressing and bending a single metal plate material to form a half of the recess 11 and one support portion 12 and welding the two together. Also good. Further, for example, the inhibition member may be manufactured by pressing and bending a single metal plate and integrally forming the concave portion and the support portion.

According to the first embodiment described in detail above, the following effects can be obtained.
(A1) In the exhaust purification apparatus 100, the inhibiting member 10 (specifically, the recess 11) is oriented so that the center lines (center line 6 and center line 4) along the respective longitudinal directions are perpendicular to the catalyst 3. Is arranged. Therefore, according to the exhaust gas purification apparatus 100, it is possible to increase the effect of reducing the deviation in the flow velocity distribution of the exhaust gas flowing into the catalyst 3 having an elliptical shape when viewed from the direction of the central axis A.

  That is, for example, when the concave portion 11 is arranged in a direction in which the center lines along the respective longitudinal directions are parallel (including overlapping) to the catalyst 3, the flow rate of the exhaust gas flowing into the catalyst 3 is The catalyst 3 tends to be biased in the short direction (short axis direction). That is, with the same idea as the configuration described in Patent Document 1 described above, a part of the flow of exhaust gas is obstructed by an elliptical recess 11 in which the shape of the catalyst 3 is slightly reduced as seen from the direction of the central axis A. Even if comprised in this way, the deviation of the flow velocity distribution of the exhaust gas flowing into the catalyst 3 is not effectively reduced. In the case of the catalyst 3 whose longitudinal direction is defined, the flow rate of the exhaust gas tends to increase as it is closer to the center of the exhaust flow channel into which the exhaust gas flows, and conversely, the flow rate of the exhaust gas decreases as it is farther from the center of the exhaust flow channel. It is thought that it is easy.

  On the other hand, in the exhaust purification apparatus 100 of the present embodiment, the recess 11 is arranged so that the center line 5 that is the short direction of the catalyst 3 and the center line 6 that is the longitudinal direction of the recess 11 overlap. For this reason, in the exhaust purification apparatus 100, the flow of the exhaust gas tends to be hindered in the short direction (short axis direction) in which the flow rate of the exhaust gas tends to be larger than the longitudinal direction (long axis direction) of the catalyst 3. Therefore, according to the exhaust gas purification apparatus 100, it is possible to increase the effect of reducing the deviation in the flow velocity distribution of the exhaust gas flowing into the catalyst 3. Such an effect is obtained because the center line 6 and the center line 4 are arranged in directions orthogonal to each other. However, the degree of orthogonality does not have to be exact, and the range in which the effect can be obtained. If it is.

  (A2) The concave portion 11 has an elliptical shape when viewed from the direction of the central axis A, and has a shape in which the width of the concave portion 11 at a position along the center line 6 increases as it approaches the center. Therefore, for example, compared to a configuration in which the width of the recess is constant, the flow in the central portion where the flow rate of the exhaust gas tends to be larger than that in the outer peripheral portion in the exhaust flow path is further inhibited, and the flow velocity distribution of the exhaust gas flowing into the catalyst 3 The effect of reducing the bias can be increased.

  (A3) In the inhibiting member 10, the length of the recess 11 along the center line 6 is shorter than the length of the catalyst 3 along the center line 5. Accordingly, a gap is formed at the end of the catalyst 3 in the direction along the center line 5 so that the flow of exhaust gas is not hindered by the recess 11. For this reason, an increase in pressure loss due to the provision of the inhibiting member 10 can be suppressed while reducing the uneven flow velocity distribution of the exhaust gas flowing into the catalyst 3.

  (A4) The inhibiting member 10 is disposed downstream of the catalyst 3 from the exhaust flow path. Therefore, there is no need to provide any member on the upstream side for reducing the uneven flow velocity distribution of the exhaust gas flowing into the catalyst 3. Therefore, it is possible to reduce the uneven flow velocity distribution of the exhaust gas flowing into the catalyst 3 while suppressing the temperature drop of the exhaust gas flowing into the catalyst 3.

[Second Embodiment]
As shown in FIG. 5, the exhaust purification device 200 of the second embodiment has a basic configuration similar to that of the exhaust purification device 100 of the first embodiment, and the inhibition member 10 described above includes the catalyst 3 in the exhaust passage. It differs in that it is provided only on the upstream side of the upstream side and the downstream side. Since other configurations are the same, description thereof is omitted.

  In the exhaust emission control device 200, the recess 11 is arranged such that the position along the central axis A is at a predetermined distance from the inflow surface of the catalyst 3. Specifically, the concave portion 11 is arranged on the upstream side of the catalyst 3 so that the surface on the concave side faces the upstream side of the exhaust passage. In addition, the position of the recessed part 11 seen from the direction of the central axis A is the same as that of 1st Embodiment, and the center line (center line 6 and center line 4) along each longitudinal direction is mutually orthogonal with respect to the catalyst 3. It is arranged in the direction to be.

According to the second embodiment described in detail above, the following effects are obtained in addition to the effects (A1) to (A3) of the first embodiment described above.
(B1) The inhibiting member 10 is disposed upstream of the catalyst 3 in the exhaust passage. Therefore, since the concave portion 11 of the inhibition member 10 directly acts on the exhaust gas before flowing into the catalyst 3, the flow velocity distribution of the exhaust gas flowing into the catalyst 3 can be easily adjusted appropriately.

  In each of the above embodiments, the center line 4 corresponds to an example of the first catalyst center line, the center line 5 corresponds to an example of the second catalyst center line, and the center line 6 corresponds to the first recess center line. The center line 7 corresponds to an example of the second recess center line.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention can take a various form, without being limited to the said embodiment.

  (C1) The flow path member 2 of each of the above embodiments is an example, and the present invention is not limited to this. For example, at least one of the first tube portion 2A, the third tube portion 2C, and the fifth tube portion 2E may be arranged so that the central axis does not overlap with the remaining at least one. Further, for example, the first tube portion 2A and the fifth tube portion 2E may have different inner diameters. For example, the cross-sectional shapes of the first tube portion 2A and the fifth tube portion 2E are not limited to a circular shape, and may be, for example, an elliptical shape or a polygonal shape.

  (C2) In each of the above embodiments, the catalyst 3 is exemplified by a ceramic three-way catalyst on which a noble metal such as platinum, palladium, or rhodium is supported. However, the present invention is not limited to this. For example, a metal catalyst may be used. Moreover, you may use catalysts and filters other than a three-way catalyst like a diesel particulate filter (Diesel Particulate Filter: DPF) and a selective reduction catalyst (Selective Catalytic Reduction: SCR).

  (C3) In each of the above embodiments, the catalyst 3 having an elliptical shape as viewed from the direction of the central axis A is exemplified, but the present invention is not limited to this. The catalyst has a shape in which the longitudinal direction is defined when viewed from the central axis direction, and has a shape that is symmetrical with respect to any of the center line along the longitudinal direction and the center line orthogonal to the center line. For example, a rectangular shape or a rhombus shape may be used.

  (C4) In each of the above embodiments, the concave portion 11 having an elliptical shape as viewed from the direction of the central axis A is exemplified, but the present invention is not limited to this. The concave portion has a shape in which the longitudinal direction is defined when viewed from the central axis direction, and the concave portion has a shape that is symmetric with respect to any of the central line along the longitudinal direction and the central line perpendicular thereto. For example, a rectangular shape or a rhombus shape may be used. Further, the concave shape of the concave portion 11 is not limited to the shape of the above embodiment.

  (C5) In each of the above embodiments, the recess 11 is provided at a position where the exhaust gas flowing out from the center of the outflow surface of the catalyst 3 collides, assuming that the flow velocity distribution of the exhaust gas flowing into the catalyst 3 is biased toward the center. Although the configuration is exemplified, the configuration is not limited to this. For example, when at least one of the exhaust flow paths of the upstream side and the downstream side of the catalyst 3 is curved or eccentric, the exhaust gas flows from the direction different from the direction along the central axis A of the catalyst 3 to the upstream side of the catalyst 3. In the supplied configuration, the flow velocity distribution of the exhaust gas flowing into the catalyst 3 can be biased to a portion other than the central portion. In such a structure, you may make it provide the recessed part 11 in the position (position where the flow velocity of exhaust gas is high) where the deviation arises. That is, the concave portion 11 may be supported at a position shifted from the central axis A of the catalyst 3. In addition, even if the position of the recessed part 11 differs, recessed part 11 itself can be made into a common design.

  (C6) In each of the above embodiments, the configuration in which the inhibiting member 10 is provided only on the downstream side or only on the upstream side of the catalyst 3 in the exhaust flow path is illustrated, but the present invention is not limited to this. The inhibiting member 10 may be provided on both the downstream side and the upstream side.

  (C7) The functions of one component in each of the above embodiments may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of each of the above embodiments may be replaced with a known configuration having a similar function. Moreover, you may abbreviate | omit a part of structure of said each embodiment as long as a subject can be solved. In addition, at least a part of the configuration of each of the above embodiments may be added to or replaced with the configuration of the other above embodiments. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present invention.

Claims (7)

A catalyst provided in the exhaust passage for purifying exhaust gas;
An inhibiting member that is provided in the exhaust flow path and reduces a deviation in the flow velocity distribution of the exhaust gas flowing into the catalyst by inhibiting a part of the flow of the exhaust gas;
With
The inhibition member has a recess that is recessed on the upstream side of the exhaust flow path, and a support portion that supports the recess at a predetermined position with respect to the catalyst, and a part of the flow of exhaust gas is inhibited by the recess.
The concave portion has a shape in which a longitudinal direction is defined when viewed from the central axis direction of the concave portion, and is perpendicular to the first concave portion center line and the first concave portion center line which are center lines along the longitudinal direction. The shape of the second recess center line that is the center line to be line-symmetrical with respect to any of the symmetry axes,
The catalyst has a shape in which a longitudinal direction is defined when viewed from the central axis direction of the catalyst, and is perpendicular to the first catalyst center line and the first catalyst center line which are center lines along the longitudinal direction. The shape of the second catalyst center line that is the center line to be line-symmetrical with respect to any of the symmetry axes,
The exhaust purification device, wherein the inhibiting member is disposed in a direction in which the first recess center line and the first catalyst center line are orthogonal to each other with respect to the catalyst. The exhaust emission control device according to claim 1,
The exhaust emission control device, wherein the recess has a shape in which the width of the recess at a position along the first recess center line is closer to the center as viewed from the central axis direction of the recess. The exhaust emission control device according to claim 1 or 2,
The exhaust purification apparatus, wherein the catalyst has a shape in which the width of the catalyst at a position along the first catalyst center line is larger as it is closer to the center when viewed from the center axis direction of the catalyst. The exhaust emission control device according to any one of claims 1 to 3, wherein
The inhibition member is an exhaust purification device, wherein a length of the concave portion along the first concave portion center line is shorter than a length of the catalyst along the second catalyst central line. An exhaust emission control device according to any one of claims 1 to 4, wherein
The exhaust purification device, wherein the inhibition member is disposed on the downstream side of the exhaust flow path with respect to the catalyst. An exhaust emission control device according to any one of claims 1 to 4, wherein
The exhaust purification device, wherein the inhibition member is disposed upstream of the catalyst in the exhaust flow path. An exhaust emission control device according to any one of claims 1 to 6,
The recess is an exhaust purification device in which a through hole is not formed.

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