JP2018076851A - Exhaust system structure for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust system structure capable of effectively utilizing an exhaust emission control part without increasing the cost.SOLUTION: The exhaust system structure includes a turbo supercharger having an exhaust port opened in a predetermined direction, and the exhaust emission control part arranged at a position away from the exhaust port in a predetermined direction and having an axis inclined to the predetermined direction for purifying exhaust gas from the exhaust port. A first edge on the peripheral edge of the upstream side end face in the exhaust gas flowing direction of the exhaust emission control part, located at the nearest position from the exhaust port, is provided on a line extending from a predetermined position on the peripheral edge of the exhaust port in a predetermined direction.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to an exhaust system structure of an internal combustion engine.

  2. Description of the Related Art Conventionally, there has been known an exhaust purification device that is provided in an exhaust system of an internal combustion engine and includes a catalyst that removes carbon monoxide, unburned hydrocarbons, and the like in exhaust gas discharged from the internal combustion engine. In order to effectively use the catalyst of the exhaust gas purification device, it is desired that the exhaust gas be allowed to uniformly flow into the upstream end of the catalyst.

  As an exhaust system structure of a conventional internal combustion engine, for example, in Patent Document 1, an exhaust pipe bent portion is provided downstream of a turbocharger, an exhaust purification contact is disposed immediately after the bent portion, and exhaust gas that has passed through the bent portion. Has been disclosed that flows into the exhaust inflow surface, which is the upstream end surface of the exhaust purification catalyst.

  In Patent Document 2, an exhaust purification device is provided in an exhaust passage connected to an exhaust manifold via a turbocharger turbine, and the direction of the outlet of the turbocharger and the direction of the inlet of the exhaust purification device are 90 degrees. What is made is disclosed.

JP 2010-159719 A JP 2009-108724 A

  However, the exhaust purification catalyst described in Patent Document 1 is disposed immediately after the bent portion, and is not disposed in the opening direction of the exhaust port of the turbocharger. Further, the exhaust gas uniformly flows into the exhaust inflow surface after passing through the baffle from the bent portion. Thus, if the rectifying plate is provided, the cost is increased, and if the rectifying plate is not provided, the exhaust gas does not uniformly flow into the exhaust inflow surface, and the catalyst cannot be effectively used. .

  Further, in the exhaust emission control device described in Patent Document 2, the direction of the inlet and the direction of the outlet of the turbocharger form 90 degrees. Since the flow rate of the exhaust gas in the exhaust passage bent at 90 degrees is higher on the outer side than on the inner side, the exhaust does not flow uniformly into the upstream end face of the exhaust gas purification device. As a result, there is a problem that the catalyst cannot be used effectively.

  An object of the present disclosure is to provide an exhaust system structure capable of effectively utilizing an exhaust purification unit without increasing costs.

The exhaust system structure of the internal combustion engine of the present disclosure is:
A turbocharger having a discharge port opened in a predetermined direction;
An exhaust gas purification unit that is disposed at a position in the predetermined direction from the exhaust port, has an axis that is inclined with respect to the predetermined direction, and purifies exhaust gas from the exhaust port;
With
A first edge located closest to the discharge port at the peripheral edge of the upstream end surface in the exhaust gas flow direction of the exhaust gas purification unit is provided on a line extending from the predetermined position of the peripheral edge of the discharge port in the predetermined direction. It is done.

The exhaust system structure of the internal combustion engine of the present disclosure is:
An exhaust passage provided such that exhaust gas flows along a predetermined direction;
An exhaust purification unit that has an axis inclined with respect to the predetermined direction and purifies exhaust gas from the exhaust passage;
With
The most upstream edge of the peripheral edge of the upstream end surface of the exhaust gas purification unit in the exhaust gas flow direction is provided on a line extending in a predetermined direction from a predetermined position of the peripheral edge of the exhaust passage.

  According to the exhaust system structure of the internal combustion engine of the present disclosure, the exhaust purification unit can be effectively used without increasing the cost.

Schematic showing an exhaust system according to an embodiment of the present disclosure Partial enlarged view of FIG. Sectional view taken along line III-III in FIG. Projection diagram of hollow cross-sectional shape projected on the upstream end face when the hollow cross-sectional shape of the straight tube is projected in the -X direction Sectional drawing which fractured | ruptured the connection structure where DOC and the straight pipe were connected along the ellipse minor axis

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, embodiment described below is an example and this invention is not limited by this embodiment.

  FIG. 1 is a schematic view showing an exhaust system according to the present invention. 1 and 2, the X axis, the Y axis, and the Z axis are drawn. In the following description, the left-right direction in FIG. 1 is referred to as the X direction or the vehicle front-rear direction, the right direction is referred to as “+ X direction” or “vehicle front side”, and the left direction is referred to as “−X direction” or “vehicle rear side”. Further, the vertical direction in FIG. 1 is referred to as the Y direction or the vehicle vertical direction, the upward direction is referred to as “+ Y direction” or “vehicle upper side”, and the downward direction is referred to as “−Y direction” or “vehicle lower side”. Further, in FIG. 1, a direction perpendicular to the paper surface is referred to as a Z direction or a vehicle width direction, a front direction is referred to as “+ Z direction” or “vehicle right side”, and a back direction is referred to as “−Z direction” or “vehicle left side”. Further, the upstream side and the downstream side in the flow direction of the exhaust gas flowing through the exhaust passage are simply referred to as “upstream side” and “downstream side”.

  As shown in FIG. 1, the exhaust system 1 extends from an exhaust manifold 3 provided on the right side of the vehicle of the engine 2, a turbocharger 4 connected to a collecting portion of the exhaust manifold 3, and the turbocharger 4. An upstream exhaust passage 5, a post-treatment device 6, and a downstream exhaust passage 7. In the case of the present embodiment, the respective members are arranged on the right side of the engine 2 in the vehicle. However, the arrangement of the members with respect to the engine 2 in the vehicle width direction is not limited to the illustrated structure.

  The direction (opening direction), size, and shape of the exhaust gas outlet 4a (corresponding to the “exhaust port” of the present invention), the size, and the shape of the turbocharger 4 are based on the shape, size, installation location, and the like of the aftertreatment device 6. It is determined comprehensively. Here, the direction of the exhaust gas outlet 4a is the -X direction. The shape of the exhaust gas outlet 4a is a general circular shape. The installation location of the post-processing device 6 is set at a position in the −X direction of the turbocharger 4.

  The upstream exhaust passage 5 is configured by an internal space of a hollow tubular straight tube 8. The straight pipe 8 causes the exhaust gas flowing into the internal space from the upstream opening to flow linearly along the extending direction of the straight pipe 8 (that is, the direction of the axis 8a (see FIG. 2)), and downstream. It has a function as a flow path that flows out from the side opening. In the case of this configuration example, the shaft 8 a corresponds to the central axis of the straight tube 8.

  The upstream end of the straight tube 8 is connected to the exhaust gas outlet 4a. On the other hand, a downstream end 8b (see FIG. 2) of the straight tube 8 is fixed to an upstream end of a case 10 (described later) of the post-processing device 6. The extending direction (the direction of the shaft 8a), the length, and the hollow cross-sectional shape of the straight tube 8 are based on the direction of the exhaust gas outlet 4a, the position, size, and shape of the DOC 11 (described later) in the aftertreatment device 6. It is determined comprehensively.

  Note that the hollow cross-sectional shape of the straight tube 8 refers to a cross-sectional shape of the internal space defined by the inner peripheral surface of the straight tube 8 (a cross-sectional shape related to a virtual plane orthogonal to the axis 8a). In other words, the hollow cross-sectional shape of the straight tube 8 matches the cross-sectional shape of the inner peripheral surface of the straight tube 8 with respect to a virtual plane orthogonal to the axis 8a.

  The extending direction of the straight tube 8 is tilted three-dimensionally based on, for example, the position of the DOC 11. Here, in order to make the explanation easy to understand, as shown in FIG. 1, the straight tube 8 is extended linearly in the same −X direction as the exhaust gas outlet 4 a. Moreover, the hollow cross-sectional shape of the straight tube 8 is the same circular shape as the shape of the exhaust gas outlet 4a.

  The reason why the extending direction and the hollow cross-sectional shape of the straight pipe 8 are the same direction and shape as the exhaust gas outlet 4a is that the flow speed of the exhaust gas flowing into the straight pipe 8 from the turbocharger 4 is reduced by the straight pipe 8 as much as possible. It is for making it flow out to DOC11, maintaining it in a high state without doing. Further, the length of the straight pipe 8 is preferably as short as possible in order to prevent heat dissipation between the turbocharger 4 and the DOC 11 and to suppress a decrease in the flow rate of the exhaust gas.

  A post-processing device 6 is connected to the downstream end 8 b of the straight tube 8. The details of the structure connecting the downstream end 8b of the straight tube 8 and the post-processing device 6 will be described later.

  As shown in FIG. 1, the aftertreatment device 6 includes a cylindrical case 10, an oxidation catalyst (DOC) 11 for purifying exhaust gas (corresponding to the “exhaust purification unit” of the present invention), and a diesel particulate filter. (DPF) 12 is accommodated. In FIG. 1, the inorganic mat 13 (see FIG. 2) described later for holding the DOC 11 and the like and the plate thickness of the case 10 are omitted.

  The DOC 11 and the DPF 12 are held in the case 10 by the inorganic mat 13 (see FIG. 2). The DOC 11 is formed in a column shape having an axis 11a. In the present embodiment, the shaft 11a corresponds to the central axis of the DOC 11. The shaft 11a extends in the direction perpendicular to the upstream end surface 11b of the DOC 11. That is, the cross-sectional shape of the DOC 11 (the cross-sectional shape related to the virtual plane orthogonal to the axis 11a) is the same shape as the upstream end surface 11b.

  Similarly, the DPF 12 is formed in a column shape having a shaft 12a. In the case of the present embodiment, the shaft 12a corresponds to the central axis of the DPF 12. The shaft 12a extends in the direction perpendicular to the upstream end surface 12b of the DPF 12. That is, the cross-sectional shape of the DPF 12 (the cross-sectional shape related to the virtual plane orthogonal to the axis 12a) is the same shape as the upstream end surface 12b.

  As described above, the installation location of the post-processing device 6 is determined at the position in the −X direction of the turbocharger 4. Here, the DOC 11 and the DPF 12 are not arranged linearly in the −X direction in order to effectively use the installation location, but each of the axes 11a and 12a is 3 in the X direction, the Y direction, and the Z direction. It is arranged to tilt in a dimension. Details of the inclinations of the axes 11a and 12a will be described later.

  In DOC11, for example, platinum, iridium oxide or cobalt oxide as an oxidation catalyst is supported on alumina as a carrier. The DOC 11 has a function of oxidizing unburned gases such as hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas. Note that the basic structure and function of the DOC 11 are the same as those of conventionally known DOCs, and thus detailed description thereof is omitted.

  The DPF 12 arranges a number of cells forming a grid-like exhaust flow path partitioned by porous ceramic partition walls along the flow direction of the exhaust gas, and alternately seals the upstream and downstream sides of these cells. It is configured to stop. The DPF 12 has a function of collecting particulate matter (PM) contained in the exhaust gas. Since the basic structure and function of the DPF 12 are the same as those of conventionally known DPFs, detailed description thereof is omitted.

  A downstream exhaust passage 7 is connected to the downstream end of the aftertreatment device 6. The exhaust gas purified by the post-treatment device 6 is led out through the downstream exhaust passage 7. The downstream side of the downstream side exhaust passage 7 extends linearly in the −X direction, and the exhaust gas is led out from the rear end of the downstream side exhaust passage 7 toward the rear of the vehicle.

  Next, details of a structure for connecting the downstream end portion 8b of the straight pipe 8 and the post-processing device 6 will be described with reference to FIG. 1 and FIG. FIG. 2 is a partially enlarged view of FIG. FIG. 2 shows a circle C as the shape of the exhaust gas outlet 4a seen from the direction of the axis 8a (that is, the hollow cross-sectional shape of the straight tube 8), and an ellipse E as the shape of the exhaust gas outlet 4a seen from the direction of the axis 11a. Indicates. FIG. 2 shows the flow of exhaust gas in the straight tube 8 and the DOC 11 with broken lines.

  The upstream end surface 11b of the DOC 11 in the exhaust gas flow direction is provided at a position in the direction of the axis 8a of the straight pipe 8 from the exhaust gas outlet 4a.

  The direction of the axis 8a of the straight tube 8 is the -X direction as described above. The axis 11a of the DOC 11 is tilted three-dimensionally with respect to the axis 8a in the -X direction. Here, for easy understanding, as shown in FIG. 2, the shaft 11a is inclined at a predetermined angle α about the Z axis (counterclockwise) with respect to the shaft 8a in the −X direction. That is, the upstream end surface 11b of the DOC 11 is inclined at a predetermined angle (π / 2−α) around the Z axis (clockwise) with respect to the shaft 8a. The inclination angle of the shaft 11a with respect to the shaft 8a is determined based on, for example, the size and shape of the DOC 11 and the arrangement location thereof.

  The upstream end surface 11b of the DOC 11 is a surface that can project the hollow cross-sectional shape (here, the circle C) of the straight tube 8 in the linear direction (−X direction). The image of the hollow cross-sectional shape projected on the upstream end surface 11b of the DOC 11 is an ellipse (ellipse E ′) having a long axis that is aligned with the long axis of the ellipse E. As shown in FIG. 2, the long axis end of the ellipse E ′ near the exhaust gas outlet 4 a coincides with the first edge 11 d as the long axis end of the ellipse E near the exhaust gas outlet 4 a. The cross-sectional shape of the DOC 11 is a circle (circle C ′ shown in FIG. 2) having the major axis of the ellipse E ′ as a diameter. Here, the “surface capable of projecting a hollow cross-sectional shape” refers to a surface capable of projecting the entire hollow cross-sectional shape. For example, when the surface is arranged out of the −X direction (projection direction), the surface is hollow. A surface on which only a part of the cross-sectional shape is projected is not required. In the present embodiment, the short axes of the ellipse E and the ellipse E ′ (the image of the hollow cross-sectional shape projected onto the upstream end face 11b of the DOC 11) are positioned on a straight line, and the short axis end Since they match each other, the ellipse E ′ is equal to the ellipse E.

  As shown in FIG. 2, the downstream end portion 8b of the straight tube 8 is formed along the peripheral edge 11c of the upstream end surface 11b of the circle C ′. In the present embodiment, the downstream end 8b of the straight pipe 8 is fitted to the upstream end edge 10a of the case 10 and welded, whereby the straight pipe 8 and the case 10 are sealed.

  Below, the connection structure which connects the downstream edge part 8b of the straight pipe 8 and the post-processing apparatus 6 is demonstrated in detail.

  The first edge 11d located closest to the exhaust gas outlet 4a at the peripheral edge 11c of the upstream end surface 11b is provided on a line extending in the −X direction from the first position 4d at the peripheral edge of the exhaust gas outlet 4a. In the case of the present embodiment, the first edge 11d corresponds to the lower end of the upstream end surface 11b in the vehicle vertical direction. The lower end as the first edge 11d is located at the same height as the lower end of the inner wall 8c of the straight tube 8 in the vehicle vertical direction.

  As shown in FIG. 2, the second edge 11e located farthest from the exhaust gas outlet 4a at the peripheral edge 11c of the upstream end surface 11b is a second position 4e (the center of the exhaust gas outlet 4a) at the peripheral edge of the exhaust gas outlet 4a. ) On the line extending in the −X direction from the position opposite to the first position 4d). In the case of this embodiment, the second edge 11e corresponds to the upper end of the upstream end surface 11b in the vehicle vertical direction. The upper end as the second edge 11e is located at the same height as the upper end of the inner wall 8c of the straight tube 8 in the vehicle vertical direction.

  The flow of exhaust gas in the connection structure as described above will be described with reference to FIG. Here, the flow of exhaust gas that hits each position in a linear region between the vicinity of the first edge 11d and the vicinity of the second edge 11e on the upstream end face 11b will be described.

  In the vicinity of the first edge 11d, the exhaust gas flowing along the −X direction from the vicinity of the first position 4d directly hits at high speed. A part of the flow flows into the DOC 11. Since the part that did not flow into the DOC 11 is blocked by the inner wall 8c of the straight tube 8 in contact with the first edge 11d from the vicinity of the first edge 11d to the outside of the upstream end face 11b, It flows from the vicinity of the first edge 11d to the vicinity of the second edge 11e along the side end face 11b. However, the ratio of the amount of exhaust gas flowing along the upstream end face 11b to the amount of exhaust gas flowing into the DOC 11 is slight. That is, most of the exhaust gas hitting the vicinity of the first edge 11d flows into the DOC 11.

  At each position between the vicinity of the first edge 11d and the vicinity of the second edge 11e on the upstream end face 11b, the ratio of the exhaust gas does not differ greatly. That is, most of the exhaust gas hitting each position flows into the DOC 11.

  In the vicinity of the second edge 11e, the exhaust gas flowing along the −X direction from the vicinity of the second position 4e hits directly at high speed. The exhaust gas hitting the vicinity of the second edge 11e is blocked by the inner wall 8c of the straight tube 8 in contact with the second edge 11e from the second edge 11e to the outside of the upstream end face 11b. As a result, most of the exhaust gas that hits the vicinity of the second edge 11 e flows into the DOC 11. Further, the exhaust gas flowing from the vicinity of the first edge 11d to the vicinity of the second edge 11e along the upstream end face 11b is blocked in the vicinity of the second edge 11e, and therefore flows into the DOC 11. .

  Next, a connection structure for connecting the straight tube 8 to the edge 11f other than the first and second edges 11d and 11e on the peripheral edge 11c of the upstream end face 11b will be described. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 3 shows a hollow cross-sectional shape of the straight tube 8 by a broken line. Further, in FIG. 3, the flow of exhaust gas is indicated by a broken line.

  As shown in FIG. 3, the straight pipe 8 has an inner wall 8f extending from the inner wall 8c to the edge 11f. The extended tip of the inner wall 8f is formed along the edge 11f of the peripheral edge 1c.

  The flow of exhaust gas in the above connection structure will be described with reference to FIG. Here, the flow of exhaust gas from each position in the region excluding the linear region on the upstream end surface 11b will be described. The exhaust gas flowing in the straight tube 8 along the −X direction changes its flow direction from the −X direction, flows along the expanded inner wall 8f, spreads in the vicinity of the edge 11f, and from the vicinity of the edge 11f. It flows into DOC11. Although the exhaust gas has a flow velocity that is reduced by the amount that spreads in the vicinity of the edge 11f, the exhaust gas directly hits the vicinity of the edge 11f, so that most of the exhaust gas that hits flows into the DOC 11.

  As described above, in the exhaust system structure of the internal combustion engine in the present embodiment, the exhaust gas from the exhaust gas outlet 4a uniformly strikes the upstream end face 11b as compared with the exhaust system structure of the conventional internal combustion engine.

<Effects of the present embodiment>
As described above, according to the exhaust system structure of the internal combustion engine according to the present embodiment, the first edge 11d located closest to the exhaust gas outlet 4a at the peripheral edge 11c of the upstream end surface 11b of the DOC 11 is the exhaust gas. It is provided on a line extending in the −X direction from the first position 4d at the periphery of the outlet 4a. As a result, in the vicinity of the first edge 11d, the exhaust gas flowing along the −X direction from the vicinity of the first position 4d directly hits at high speed. As a result, most of the exhaust gas that hits the vicinity of the first edge 11d flows into the DOC 11, so that the DOC 11 can be used effectively.

  Further, according to the above-described embodiment, the second edge 11e located farthest from the exhaust gas outlet 4a at the peripheral edge 11c of the upstream end surface 11b of the DOC 11 extends from the second position 4e at the peripheral edge of the exhaust gas outlet 4a. It is provided on a line extending in the X direction. Thereby, in the vicinity of the second edge 11e, the exhaust gas flowing along the −X direction from the vicinity of the second position 4e directly hits at high speed. As a result, most of the exhaust gas that hits the vicinity of the second edge 11e flows into the DOC 11, so that the DOC 11 can be used effectively.

  Further, according to the above-described embodiment, the straight pipe 8 is provided so that the exhaust gas from the exhaust gas outlet 4a flows along the shaft 8a, and the downstream end 8b of the straight pipe 8 is connected to the DOC 11. As a result, the exhaust gas from the straight pipe 8 is rectified along the axis 8a while maintaining a high flow rate, and hits the upstream end face 11b of the DOC 11 uniformly and directly. For this reason, the purification | cleaning capability of DOC11 can be raised. Further, the DOC 11 can be downsized by the amount that the purification ability of the DOC 11 is increased. Further, the cost can be reduced by the amount that the DOC 11 is miniaturized. Further, the straight pipe 8 can be made as short as possible, and the DOC 11 can be arranged immediately after the exhaust gas outlet 4a. Thereby, since the heat radiation between the turbocharger 4 and the DOC 111 can be prevented, warm-up can be promoted by preventing the engine heat in the warm-up operation from being released to the outside.

  Further, according to the above embodiment, the upstream end surface 11 b of the DOC 11 is inclined with respect to the axis 8 a of the straight tube 8. As a result, since the exhaust gas from the straight pipe 8 directly flows into the DOC 11, there is no need to provide a turning means for changing the flow direction of the exhaust gas from the straight pipe 8 to the direction of the upstream end face 11b. Can be reduced.

<Modification of the present embodiment>
In the above embodiment, the cross-sectional shape of the DOC 11 has an outer shape of a circle C ′ whose diameter is the major axis of the ellipse E. In this case, the exhaust gas flowing in the straight tube 8 along the −X direction flows along the inner wall 8f and spreads in the vicinity of the edge 11f of the upstream end surface 11b, and the flow rate of the exhaust gas decreases by the amount of spread. . In order to further increase the exhaust processing capacity of the DOC 11, it is preferable to apply exhaust gas to the upstream end face 11b as fast as possible.

  Next, a modification of the present embodiment will be described with reference to FIGS. FIG. 4 is a projection of the hollow cross-sectional shape projected onto the upstream end surface 11b when the hollow cross-sectional shape of the straight tube 8 is projected in the −X direction. FIG. 5 is a cross-sectional view of the connection structure in which the DOC 11 and the straight tube 8 are connected, broken along the short axis of the ellipse E. In FIG. 4, the upstream side according to the above-described embodiment in which the ellipse E as the shape of the upstream end face 11 b ′ according to the modification, the circle C as the hollow cross-sectional shape of the straight tube 8, and the major axis of the ellipse E is the diameter. A circle C ′ as a shape of the end face 11b is shown. FIG. 4 shows the first and second edges 11d and 11e as intersections between the outer shape of the ellipse E and the major axis, and the third edge 11g as the intersection between the outer shape of the ellipse E and the minor axis. . FIG. 5 shows the exhaust gas flow in broken lines.

  The cross-sectional shape of the DOC 11 is such that the hollow cross-sectional shape of the straight tube 8 (here, the circle C shown in FIG. 2) is in the −X direction with respect to the upstream end surface 11b inclined at a predetermined angle (π / 2−α). When projected along, it has the same outer shape as the projected hollow cross-sectional shape. That is, the outer shape of the cross-sectional shape of the DOC 11 is an ellipse E shown in FIG.

  The downstream end portion 8b of the straight tube 8 is formed along the peripheral edge 11c of the upstream end surface 11b of the ellipse E as shown in FIG. In the modification, it is formed along the downstream end 8b of the straight tube 8 on the peripheral edge 11c including the third edge 11g. Further, the downstream end portion 8b of the straight tube 8 is fitted to the upstream end edge 10a of the case 10 and welded, whereby the straight tube 8 and the case 10 are sealed. The connection structure for connecting the straight tube 8 and the DOC 11 is different from the above-described embodiment in which the extended end of the inner wall 8f is formed along the edge 11g in the peripheral edge 11c.

  In the upstream end face 11b ′ according to the modification in which the hatched area is deleted from the circle C ′ shown in FIG. 4 and the outer shape is the ellipse E, the area of the ellipse E is within the straight tube 8 as shown in FIG. There is no room for the exhaust gas to spread linearly along the axis 8a and while maintaining a high flow rate, it is a region that hits more uniformly, and the exhaust gas that hits uniformly flows into the DOC 11 uniformly. Can be used more effectively. Compared with the DOC 11 according to the above-described embodiment, the DOC 11 can be reduced in size and the cost can be reduced by the amount that can effectively use the DOC 11. Here, when it is more uniform, the exhaust gas hits and flows into the upstream end face 11b ′ of the ellipse E according to the modified example and the exhaust gas hits and flows into the upstream end face 11b of the circle C ′ according to the above embodiment. It means that it is even more uniform with respect to the inflow.

<Effect of modification>
According to the exhaust system structure of the internal combustion engine according to the modification, the cross-sectional shape of the DOC 11 is projected when the hollow cross-sectional shape of the straight tube 8 is projected along the −X direction with respect to the upstream end surface 11b. It has the same outer shape as the outer shape of the ellipse E as a hollow cross-sectional shape. Thereby, since the area | region of the ellipse E in the upstream end surface 11b turns into an area | region where the exhaust gas from the straight pipe | tube 8 hits more uniformly, DOC11 can be utilized still more effectively.

<Other variations>
In the above embodiment, the exhaust purification unit as the DOC 11 is provided at a position in the −X direction from the exhaust gas outlet 4 a of the turbocharger 4. The present invention is not limited to this, and for example, an exhaust purification unit may be provided on the downstream side of the exhaust passage through which exhaust gas flows along a predetermined direction. In this case, the most upstream edge of the upstream end face 11b is provided on a line extending in a predetermined direction from a predetermined position on the periphery of the exhaust passage. Moreover, the edge located in the most downstream side in the upstream end surface 11b is provided on the line extended in a predetermined direction from the predetermined position of the periphery of an exhaust passage.

  Moreover, in the said embodiment, although the straight tube 8 was extended to the vehicle rear side, this invention is not limited to this, For example, it is extended to the vehicle front side according to the installation place of the post-processing apparatus 6, etc. May be.

  In the above embodiment, the shaft 12a of the DPF 12 is tilted two-dimensionally at a predetermined angle β around the Z axis with respect to the shaft 11a of the DOC 11, as shown in FIG. Depending on the shape and the location of the arrangement, the shaft 11a may be tilted three-dimensionally.

  In the above embodiment, the first edge 11d is provided on the line extending in the −X direction from the first position 4d at the periphery of the exhaust gas outlet 4a, and is extended in the −X direction from the second position 4e. A second edge 11e is provided on the line. However, the present invention is not limited to this. For example, the first edge 11d is provided on a line extending in the −X direction from the first position 4d at the periphery of the exhaust gas outlet 4a. The second edge 11e does not have to be provided on the line extending to the line. Even in this configuration, the exhaust purification capacity of the DOC 11 can be increased as compared with the conventional art.

  Moreover, although the said embodiment demonstrated what provided DOC11 in the upstream of DPF12, it is not limited to this. Various catalysts for purifying exhaust gas such as a lean NOx trap catalyst (LNT) and a selective catalytic reduction catalyst (SCR) as other catalysts may be provided on the upstream side of the DPF 12, and the DOC 11 In addition, another catalyst may be provided. When the present invention is applied to this configuration, the axis of the LNT is inclined at a predetermined angle with respect to the axis 8 a of the straight tube 8.

  The exhaust system structure of the internal combustion engine of the present disclosure is useful as an exhaust gas aftertreatment device that requires effective use of an exhaust purification unit.

DESCRIPTION OF SYMBOLS 1 Exhaust system 2 Engine 3 Exhaust manifold 4 Turbocharger 4a Exhaust gas outlet 5 Upstream exhaust passage 6 Post-processing device 7 Downstream exhaust passage 8 Straight pipe 8a Shaft 8b Downstream end 10 Case 11 DOC
11a shaft 11b upstream end face 12 DPF
12a shaft 12b upstream end face

Claims (6)

A turbocharger having a discharge port opened in a predetermined direction;
An exhaust gas purification unit that is disposed at a position in the predetermined direction from the exhaust port, has an axis that is inclined with respect to the predetermined direction, and purifies exhaust gas from the exhaust port;
With
A first edge located closest to the discharge port at the peripheral edge of the upstream end surface in the exhaust gas flow direction of the exhaust gas purification unit is provided on a line extending from the predetermined position of the peripheral edge of the discharge port in the predetermined direction. An exhaust system structure of an internal combustion engine.   2. The exhaust system structure for an internal combustion engine according to claim 1, wherein the first edge is provided on a line extending in the horizontal direction from a lower end position of a peripheral edge of the discharge port opened in the horizontal direction.   A second edge located farthest from the discharge port at the peripheral edge of the upstream end surface extends in a predetermined direction from a position opposite to the predetermined position with respect to the center of the discharge port at the peripheral edge of the discharge port. The exhaust system structure for an internal combustion engine according to claim 2, wherein the exhaust system structure is provided on a line that is connected to the engine.   The exhaust system structure for an internal combustion engine according to claim 3, wherein the second edge is provided on a line extending in the horizontal direction from an upper end position of a peripheral edge of the discharge port opened in the horizontal direction.   The exhaust of the internal combustion engine according to any one of claims 1 to 4, further comprising an exhaust passage provided so that exhaust gas from the exhaust port flows along the predetermined direction and connected to the exhaust purification unit. System structure. An exhaust passage provided such that exhaust gas flows along a predetermined direction;
An exhaust purification unit that has an axis inclined with respect to the predetermined direction and purifies exhaust gas from the exhaust passage;
With
An exhaust system of an internal combustion engine in which the most upstream edge of the peripheral edge of the upstream end surface in the exhaust gas flow direction of the exhaust gas purification unit is provided on a line extending in a predetermined direction from a predetermined position of the peripheral edge of the exhaust passage. Construction.

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