JP2019035349A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

To provide an exhaust emission control device of an internal combustion engine enabling uniformization for gas to a catalyst converter, and capable of preventing flow of exhaust from one cylinder from interrupting flow of exhaust from another cylinder.SOLUTION: An exhaust emission control device of an internal combustion engine is configured such that a bent part 132 bent downward on a downstream side of an exhaust sensor is provided at an exhaust pipe; at the bent part 132, a swollen part 134 swollen to the outside of bending with respect to an inlet of exhaust emission control means is provided; and a swollen amount on the other side of the swollen part 134 swollen to the outside of the bending with respect to an inlet 151 of the exhaust emission control means is larger than a swollen amount of one side thereof.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine. More specifically, the present invention relates to an exhaust gas purification apparatus for an internal combustion engine that rectifies exhaust gas.

  Conventionally, various studies have been made on the rectifying structure of an exhaust system of an internal combustion engine, and a technique for improving the gas contact with an exhaust sensor provided in the exhaust system is known. For example, the exhaust sensor is arranged without being inclined with respect to a vertical line (usually a vertical line) perpendicular to the vertical axis of the central axis of the exhaust passage, but from the viewpoint of ensuring layout restrictions and good maintainability Therefore, the exhaust sensor is arranged with an inclination with respect to the perpendicular, and the exhaust sensor is pushed into the exhaust passage together with the mounting seat surface. Techniques for improvement are known (see, for example, Patent Document 1).

Japanese Patent No. 5875564

  In the prior art described in the above publication, the gas contact to the exhaust sensor is improved, but further, it is required to make the gas contact to the catalytic converter disposed downstream of the exhaust sensor uniform. It was.

  The present invention has been made in view of the above problems, and an object of the present invention is to make the per-gas uniformity to the catalytic converter uniform, and the exhaust flow from one cylinder backflows and the exhaust from the other cylinders. An object of the present invention is to provide an exhaust emission control device for an internal combustion engine capable of suppressing the obstruction of the flow of the engine.

  In order to achieve the above object, the present invention provides an exhaust port (for example, exhaust ports 11a to 11f to be described later) extending from each cylinder (for example, a first to third cylinders to be described later) of an internal combustion engine (for example, an engine to be described later). An exhaust collecting portion (for example, an exhaust manifold 12 described later) that is formed by collecting and collects exhaust discharged from each cylinder, and an exhaust gas that is provided on the downstream side of the exhaust collecting portion and collects at the exhaust collecting portion. Are attached to an exhaust pipe (for example, an after-mentioned exhaust pipe 13) that guides the exhaust gas to a downstream side exhaust purification means (for example, an after-mentioned catalytic converter 15), and an upper surface wall (for example, an after-mentioned upper surface wall 131a) of the exhaust pipe, In a cross-sectional view orthogonal to a central axis (for example, a later-described center axis X) of the exhaust collecting portion in a connection portion (for example, a flange 10 described later) of the exhaust collecting portion and the exhaust pipe, An exhaust sensor (for example, an air-fuel ratio sensor 14 described later) disposed at a possible position, and a bent portion (for example, a bent portion 132 described later) provided in the exhaust pipe and bent downward on the downstream side of the exhaust sensor. And a bulging portion (for example, a later-described bulging portion 134 described later) that is provided in the bent portion and bulges outward from the inlet (for example, an opening 151 described later) of the exhaust gas purification unit. An exhaust purification device (for example, an exhaust purification device 1 described later) is provided. In the exhaust gas purification apparatus for an internal combustion engine according to the present invention, a mounting seat surface (for example, a mounting seat surface 14a described later) of the exhaust sensor protrudes into the exhaust pipe, and the exhaust sensor is vertically The exhaust sensor is arranged so as to be inclined with respect to a perpendicular (for example, a perpendicular Y described later) perpendicular to the direction, and the area of the exhaust sensor on both sides of the perpendicular in the sectional view is one side (for example, the third cylinder side described later). ) Is smaller than the other side (for example, the first cylinder side described later), and the other side bulge bulges outward from the inlet of the exhaust gas purification means at the bulge portion. The amount is larger than the bulging amount on the one side.

In the present invention, in the bulging portion, the bulging amount on the other side that bulges outward from the inlet of the exhaust gas purification means is larger than the bulging amount on the one side.
As a result, the exhaust discharged from each cylinder is guided along the bulging portion and is smoothly guided downward on the downstream side of the exhaust sensor by the portion of the bulging portion where the bulging amount is small. For this reason, the gas contact with the exhaust gas purification means is made uniform, and the exhaust flow from one cylinder is prevented from flowing back and obstructing the exhaust flow from the other cylinders. As a result, the purification rate of the exhaust gas purification means can be increased, and the engine output can be prevented from decreasing. At the same time, it is possible to suppress the separation of the exhaust gas while taking into consideration the restrictions on the layout and ensuring good maintainability, to improve the gas contact with the exhaust sensor, and to improve the detection accuracy of the exhaust sensor.

  The amount of protrusion of the mounting seat surface to the inside of the exhaust pipe is preferably larger on the other side than on the one side.

  In this invention, the amount of protrusion of the mounting seat surface to the inside of the exhaust pipe is larger on the other side than on the one side. As a result, the exhaust discharged from the other side can be guided downward on the downstream side of the exhaust sensor due to the difference in the protruding amount on the mounting seat surface.

  According to the present invention, it is possible to make the per gas per unit to the catalytic converter uniform and to prevent the flow of exhaust from one cylinder from flowing backward and obstructing the flow of exhaust from other cylinders. An exhaust emission control device for an internal combustion engine can be provided.

1 is a top view of an exhaust gas purification apparatus for an internal combustion engine according to an embodiment of the present invention. It is a side view of the exhaust emission control device of the internal combustion engine according to the embodiment. It is sectional drawing which cut | disconnected perpendicularly | vertically with respect to the central axis line of an exhaust manifold in the flange part, and looked at the exhaust gas purification apparatus of the internal combustion engine which concerns on the said embodiment from the upstream. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is a perspective view which shows a mode when removing an air fuel ratio sensor. It is the figure which looked at the mode when removing an air fuel ratio sensor from the vehicles front side. FIG. 3 is a cross-sectional view of the exhaust gas purification apparatus for an internal combustion engine according to the embodiment, as viewed from the downstream side, cut perpendicularly to the central axis of the exhaust manifold on the mounting seat surface of the air-fuel ratio sensor. FIG. 3 is a cross-sectional view of the exhaust gas purification apparatus for an internal combustion engine according to the embodiment, as viewed from the upstream side by cutting perpendicularly to the central axis of the exhaust manifold at the upstream end of the exhaust pipe. It is sectional drawing which cut | disconnected the exhaust gas purification apparatus of the internal combustion engine which concerns on the said embodiment in the up-down direction on the central axis line of an exhaust manifold. It is a top view for demonstrating operation | movement of the exhaust gas purification apparatus of the internal combustion engine which concerns on the said embodiment. It is a side view for demonstrating operation | movement of the exhaust gas purification apparatus of the internal combustion engine which concerns on the said embodiment. It is a schematic diagram for demonstrating operation | movement of the exhaust gas purification apparatus of the internal combustion engine which concerns on the said embodiment.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a top view of an exhaust purification device 1 of an internal combustion engine (hereinafter referred to as “engine”) according to an embodiment of the present invention. FIG. 2 is a side view of the exhaust emission control device 1 for the engine according to the present embodiment. FIG. 3 is a cross-sectional view of the engine exhaust purification device 1 according to the present embodiment as viewed from the upstream side by cutting perpendicularly to the central axis of the exhaust manifold at the flange portion. 4 is a cross-sectional view taken along line AA in FIG. 1 and 4 represents the central axis X of the exhaust manifold 12.

As shown in FIG. 1, the engine of the present embodiment is an inline three-cylinder engine for a light vehicle, and an exhaust purification device 1 includes exhaust ports 11a to 11f extending from three cylinders of an engine (not shown), and An exhaust manifold 12 as an exhaust collecting portion where the exhaust ports 11a to 11f gather, an exhaust pipe 13 provided on the downstream side of the exhaust manifold 12, an air-fuel ratio sensor 14 provided in the exhaust pipe 13, and an exhaust pipe 13 And a catalytic converter (not shown) provided on the downstream side.
Further, a flange portion 10 is provided between the downstream end portion of the exhaust manifold 12 and the upstream end portion of the exhaust pipe 13 as a connecting portion that connects and fastens them. That is, the exhaust purification device 1 is an exhaust purification device in which an exhaust manifold 12 and a cylinder head (not shown) are integrated.

The exhaust ports 11a and 11b are connected to the first cylinder (CYL1). Exhaust gas discharged from the first cylinder is introduced into the exhaust manifold 12 via these exhaust ports 11a and 11b.
The exhaust ports 11c and 11d are connected to the second cylinder (CYL2). Exhaust gas discharged from the second cylinder is introduced into the exhaust manifold 12 through the exhaust ports 11c and 11d.
The exhaust ports 11e and 11f are connected to the third cylinder (CYL3). Exhaust gas discharged from the third cylinder is introduced into the exhaust manifold 12 through the exhaust ports 11e and 11f.
The first cylinder (CYL1), the second cylinder (CYL2), and the third cylinder (CYL3) are arranged in parallel.

The exhaust manifold 12 is configured to include three branch pipes 122a to 122c and a collecting portion 121 in which the three branch pipes 122a to 122c are gathered. The branch pipe 122a is formed by collecting exhaust ports 11a and 11b, the branch pipe 122b is formed by collecting exhaust ports 11c and 11d, and the branch pipe 122c is formed by collecting exhaust ports 11e and 11f. The exhaust manifold 12 collects exhaust from each of the exhaust ports 11a to 11f via the three branch pipes 122a to 122c and the collecting part 121.
The central axis X of the exhaust manifold 12 means the central axis of the collecting portion 121.

  The upstream end of the exhaust pipe 13 is connected to the downstream end of the exhaust manifold 12 via the flange portion 10. Exhaust gas collected by the exhaust manifold 12 flows into the exhaust pipe 13. As shown in FIG. 2, the exhaust pipe 13 is, in order from the upstream side, a straight portion 131 that extends substantially linearly in the horizontal direction, a bent portion 132 that bends downward from the straight portion 131, and the downstream side. And a connecting portion 133 that is connected to the catalytic converter 15 after being expanded in diameter. The exhaust gas introduced into the exhaust pipe 13 is introduced into the catalytic converter 15 below through the straight portion 131, the bent portion 132 and the connecting portion 133.

  The catalytic converter 15 includes an exhaust purification catalyst that purifies harmful components in the exhaust in a substantially cylindrical casing (not shown). As the exhaust purification catalyst, for example, a honeycomb structure in which a three-way catalyst for purifying HC, CO and NOx in the exhaust is carried is used. Exhaust gas introduced into the catalytic converter 15 is purified by removing harmful components by the action of the exhaust purification catalyst.

  The air-fuel ratio sensor 14 is an exhaust sensor that detects the oxygen concentration in the exhaust. As shown in FIGS. 1 and 2, the air-fuel ratio sensor 14 is attached to the upper surface wall 131 a of the straight portion 131 of the exhaust pipe 13 in an inclined state. The air-fuel ratio sensor 14 includes a detection unit 141 and a sensor main body unit 140, and only the detection unit 141 is inserted into the exhaust pipe 13 from above. As shown in FIG. 3, the air-fuel ratio sensor 14 is disposed at a position where the air-fuel ratio sensor 14 can be seen in a cross-sectional view orthogonal to the central axis X of the exhaust manifold 12 in the flange portion 10.

  The detection unit 141 has a substantially cylindrical shape and is provided at the tip of the sensor main body 140. The detection unit 141 is configured by covering a detection element (not shown) provided on the central axis of the air-fuel ratio sensor 14 with a cylindrical cover 142. The front end of the cover 142 has a reduced diameter, and a front end exhaust introduction hole 143 is formed at the center of the front end surface of the front end portion 142a. Further, a plurality of side exhaust introduction holes 144 are formed in the side surface portion of the cover 142 at substantially equal intervals in the circumferential direction. The exhaust gas is introduced from the tip exhaust introduction hole 143 and the side exhaust introduction hole 144, whereby the oxygen concentration in the exhaust is detected.

  As shown in FIGS. 1 to 3, the flange portion 10 is integrally formed with the upstream end portion of the exhaust pipe 13 by welding. The flange portion 10 is formed of a substantially triangular thin plate. Three fastening holes 10 a to 10 c for connecting and fastening the exhaust manifold 12 and the exhaust pipe 13 are provided at each apex of the flange portion 10. The flange portion 10 is formed with extending portions 10d and 10f provided with fixing holes 10e and 10g for fixing and supporting an exhaust purification device cover (not shown).

  As shown in FIG. 3, a communication hole 100 is formed in the center of the flange portion 10 to communicate the collecting portion 121 of the exhaust manifold 12 and the exhaust pipe 13. The communication hole 100 is a long hole extending in the left-right direction (horizontal direction), and both ends thereof are formed in an arc shape.

  3 is a virtual straight line that extends in the left-right direction (horizontal direction) through the center of the communication hole 100 and divides the communication hole 100 into two. In the cross-sectional view of FIG. 3, the air-fuel ratio sensor 14 is arranged so that at least a part of the side surface exhaust introduction hole 144 is located on this AA line. Thereby, the main flow of the exhaust gas flowing through the communication hole 100 is easily introduced into the side surface exhaust introduction hole 144.

  As shown in FIG. 4, the exhaust pipe 13 around the air-fuel ratio sensor 14 has a substantially circular shape in the cross-section taken along the line AA in FIG. 3, and the exhaust flow is disturbed around the air-fuel ratio sensor 14. There is no such thing. In addition, the air-fuel ratio sensor 14 is disposed so as to be positioned at the approximate center of the exhaust pipe 13 having a substantially circular cross section. Further, as will be described later, the air-fuel ratio sensor 14 is disposed on the central axis X of the exhaust manifold 12 so that the tip exhaust introduction hole 143 is located.

The attachment position of the air-fuel ratio sensor 14 will be described in more detail with reference to FIGS.
FIG. 5 is a perspective view showing a state when the air-fuel ratio sensor 14 is removed during maintenance. FIG. 6 is a view of the state when the air-fuel ratio sensor 14 is removed during maintenance as viewed from the front side of the vehicle (viewed from the direction of the white arrow in FIG. 5).
As shown in FIGS. 5 and 6, in the exhaust purification device 1 of the present embodiment, the air-fuel ratio sensor 14 is disposed directly below the bulkhead B as a structural wall that separates the engine room and the passenger compartment. This is because the target vehicle is a mini vehicle and there is no degree of freedom in the arrangement of the exhaust purification device 1 and there are restrictions on the layout.

  Incidentally, since the air-fuel ratio sensor 14 is attached to the upper surface wall 131a of the exhaust pipe 13 by screws, when removing the air-fuel ratio sensor 14 during maintenance, it is necessary to rotate the air-fuel ratio sensor 14 and remove it. Specifically, as shown in FIGS. 5 and 6, the operator uses the long tool T to open and close the operation units T <b> 1 and T <b> 1. Then, the main body T2 with which the air-fuel ratio sensor 14 is engaged is rotated, whereby the air-fuel ratio sensor 14 is rotated and can be removed. Thus, since it is necessary to use a long tool at the time of removal, there are further restrictions on the arrangement of the air-fuel ratio sensor 14 in order to ensure good maintainability.

  Here, FIG. 7 is a cross-sectional view of the exhaust purification device 1 according to the present embodiment as viewed from the downstream side by cutting perpendicularly to the central axis X of the exhaust manifold 12 on the mounting seat surface of the air-fuel ratio sensor 14. is there. FIG. 8 is a cross-sectional view of the exhaust emission control device 1 according to this embodiment as viewed from the upstream side by cutting perpendicularly to the central axis X of the exhaust manifold 12 at the upstream end of the exhaust pipe 13. FIG. 8 is a cross-sectional view of the flange portion 10 cut perpendicularly to the central axis X of the exhaust manifold 12 and viewed from the upstream side. In FIG. .

  As shown in FIGS. 7 and 8, due to the above-mentioned restrictions, first, the air-fuel ratio sensor 14 is arranged so that its mounting seat surface 14a protrudes into the exhaust pipe 13, and the exhaust gas on the mounting seat surface 14a is exhausted. The mounting seat surface 14a is inclined so that the amount of protrusion to the inside of the pipe 13 is larger on the other side (the first cylinder (CYL1) side) than on the one side (the third cylinder (CYL3) side). Projecting to the inside of the exhaust pipe 13. That is, the air-fuel ratio sensor 14 is disposed so as to protrude into the exhaust pipe 13 as compared with the conventional case.

  The air-fuel ratio sensor 14 is disposed so as to be inclined with respect to a vertical line Y perpendicular to the central axis X of the exhaust manifold 12 in the vertical direction (vertical direction). Specifically, in the present embodiment, the air-fuel ratio sensor 14 is inclined and arranged so that the sensor main body 140 faces the first cylinder (CYL1) side and the detection unit 141 faces the third cylinder (CYL3) side. (See FIG. 1).

More specifically, as shown in FIG. 8, in a cross-sectional view orthogonal to the central axis X of the exhaust manifold 12, the air-fuel ratio sensor 14 has an area of the air-fuel ratio sensor 14 on both sides of the vertical line Y, and one side is the other. Inclined so as to be smaller than the side. Specifically, in the present embodiment, the air-fuel ratio sensor 14 is such that the area of the air-fuel ratio sensor 14 on both sides of the vertical line Y is smaller on the third cylinder (CYL3) side than on the first cylinder (CYL1) side. It is inclined and arranged.
At the same time, as shown in FIGS. 7 and 8, the air-fuel ratio sensor 14 is arranged so that the tip exhaust introduction hole 143 is located on the vertical line Y in a cross-sectional view orthogonal to the central axis X of the exhaust manifold 12.

  Therefore, as is apparent from FIGS. 7 and 8, the distance from the side wall of the exhaust pipe 13 immediately upstream of the air-fuel ratio sensor 14 to the side exhaust introduction hole 144 of the air-fuel ratio sensor 14 is the third cylinder (CYL3) side. Is larger than the first cylinder (CYL1) side. Therefore, in the present embodiment, the upstream side of the air-fuel ratio sensor 14 is reduced so that the cross-sectional area of the exhaust pipe 13 is small on either the third cylinder (CYL3) side or the first cylinder (CYL1) side. A throttle structure is formed on the side wall of the exhaust pipe 13, and the throttle amount on the third cylinder (CYL3) side where the distance from the side wall to the side exhaust introduction hole 144 of the air-fuel ratio sensor 14 is large is the first cylinder (CYL1). ) Is set larger than the aperture amount on the side.

FIG. 9 is a cross-sectional view of the exhaust emission control device 1 according to the present embodiment as viewed in the vertical direction on the central axis X of the exhaust manifold 12. FIG. 9 shows a cross section of the exhaust pipe 13 on the third cylinder (CYL3) side in which the throttle amount is set larger.
As shown in FIG. 9, a throttle structure 13a is formed on the side wall of the exhaust pipe 13 immediately upstream of the air-fuel ratio sensor 14 so as to protrude into the exhaust pipe 13 and gently incline downward toward the downstream side. As described above, the throttling structure 13a on the third cylinder (CYL3) side has substantially the same shape as the throttling structure on the first cylinder (CYL1) side (not shown), but has a protrusion depth (throttle restriction). The amount is set larger on the third cylinder (CYL3) side.

  Further, the throttle structure 13a is formed at a position where the main flow of exhaust from the exhaust ports 11a, 11b on the first cylinder (CYL1) side facing each other via the exhaust manifold 12 collides. More specifically, as shown in FIG. 9, the throttle structure 13 a is formed to extend from the position where the main flow of exhaust collides to the vicinity of the detection unit 141 of the air-fuel ratio sensor 14.

  As shown in FIG. 9, the bent portion 132 is provided with a bulging portion 134. The bulging portion 134 bulges outside the bent portion 132 from the inlet of the catalytic converter 15. More specifically, the bulging portion 134 bulges up to a predetermined position radially outside the opening with respect to the edge of the opening 151 at the lower end of the connection portion 133 that forms the inlet of the catalytic converter 15.

  As shown in FIGS. 1 and 4, the bulging portion 134 has an asymmetric shape with respect to the central axis X, and bulges outward from the inlet of the catalytic converter 15 at the bulging portion 134. The bulge amount on the other side (the first cylinder (CYL1) side) is larger than the bulge amount on the one side (the third cylinder (CYL3) side). In addition, the inner surface of the bulging portion 134 on one side (the third cylinder (CYL3) side) where the bulging amount is small is subjected to press molding for making the asymmetric shape, so that the exhaust pipe An inwardly extending portion 135 suppresses the amount of outward bulging on the inner surface of the bulging portion 134 of the exhaust pipe 13. One side of the bulging portion 134 in the exhaust pipe 13 (the third cylinder (CYL3 ) Side) and the other side (the first cylinder (CYL1) side) portion of the bulging portion 134, the difference in the outward bulging amount is configured to be larger. .

The operation of the exhaust emission control device 1 for an engine according to this embodiment having the above configuration will be described with reference to FIG.
FIG. 10 is a diagram for explaining the operation of the engine exhaust gas purification apparatus 1 according to the present embodiment. Specifically, FIG. 10 is a top view showing an exhaust flow of the engine exhaust gas purification apparatus 1 according to the present embodiment. FIG. 10 shows the exhaust flow of each cylinder, and the black portion indicates that the exhaust flow rate is higher.

  As shown in FIG. 10, it is understood that all the exhaust discharged from each cylinder (each PORT) converges without being separated, and most of the exhaust flows toward the air-fuel ratio sensor 14. In particular, the exhaust gas (exhaust gas from the first cylinder in the present embodiment) flowing into the side where the distance from the side wall has become larger due to the air-fuel ratio sensor 14 being attached to the exhaust pipe 13 with an inclination is also peeled off. It can be seen that it converges without any problems and flows smoothly toward the air-fuel ratio sensor 14. In this way, in the exhaust purification device 1 of the present embodiment, the gas contact with the air-fuel ratio sensor 14 is good, thereby improving the detection accuracy of the air-fuel ratio sensor 14.

  Further, as shown in FIGS. 10 and 11, all the exhaust discharged from each cylinder is guided to the bulging portion 134, and the bulging portion 134 having an asymmetric shape with respect to the central axis X. It can be seen that the bulging portion 134 has a small bulging amount along the inner surface of the bulging portion 134 and is smoothly guided downward (lower side in FIG. 11). For this reason, the gas contact with the catalytic converter 15 is made uniform, and as shown in FIG. 10, the exhaust discharged from the first cylinder (CYL1), the second cylinder (CYL2), and the third cylinder (CYL3). It can be seen that there is almost no reverse flow to the other cylinders.

  That is, for example, as shown in “3PORT” in FIG. 10, the exhaust discharged from the third cylinder (CYL3) passes around the air-fuel ratio sensor 14 at the bent portion 132 as shown by the arrow in FIG. It goes around to the other side (the first cylinder (CYL1) side) and is guided along the bulging portion 134 to make a half turn.

Thereafter, at a position indicated by a broken-line circle, the exhaust gas does not turn horizontally from one side (the third cylinder (CYL3) side) to the first cylinder (CYL1), but is asymmetrical with respect to the central axis X. The flow along the portion of the protruding portion 134 along which the bulging amount is small is smoothly guided to the lower side of the air-fuel ratio sensor 14 (in the direction from the front to the back of FIG. 12). In particular, since the portion 135 located inside the exhaust pipe is provided on one side (the third cylinder (CYL3) side) of the bulging portion 134, the exhaust is guided more smoothly.
In this way, in the exhaust purification device 1 of the present embodiment, the purification rate of the catalytic converter 15 is increased, and the exhaust flow from one cylinder does not flow backward, obstructing the flow of exhaust from other cylinders. The engine output is kept from decreasing.

According to this embodiment, the following effects are produced.
In the present embodiment, the mounting seat surface 14 a of the air-fuel ratio sensor 14 provided on the upper surface wall 131 a of the exhaust pipe 13 on the downstream side of the exhaust manifold 12 is provided so as to protrude into the exhaust pipe 13. In addition, the air-fuel ratio sensor 14 is disposed at a visible position in a cross-sectional view perpendicular to the central axis X of the exhaust manifold 12 in the flange portion 10 and is perpendicular to the vertical line Y perpendicular to the central axis X. It was placed at an angle. Further, a bent portion 132 that is bent downward on the downstream side of the air-fuel ratio sensor 14 is provided in the exhaust pipe 13. Further, a bulging portion 134 that bulges outward from the inlet of the catalytic converter 15 is provided in the bent portion 132. Further, the bulging amount on the other side that bulges outward from the inlet of the catalytic converter 15 in the bulging portion 134 is configured to be larger than the bulging amount on one side.
As a result, the exhaust discharged from each cylinder is guided along the portion of the bulging portion 134 where the bulging amount is small, and smoothly led downward on the downstream side of the air-fuel ratio sensor 14. For this reason, the gas contact with the catalytic converter 15 is made uniform, and the exhaust flow from one cylinder is prevented from flowing back and obstructing the exhaust flow from the other cylinders. As a result, the purification rate of the catalytic converter 15 can be increased, and the decrease in engine output can be suppressed. At the same time, since it is possible to suppress the separation of exhaust gas while taking into consideration the constraints on the layout and ensuring good maintainability, the gas contact with the air-fuel ratio sensor 14 can be improved, and the detection accuracy of the air-fuel ratio sensor 14 is improved. it can.

  The amount of protrusion of the mounting seat surface 14a toward the inside of the exhaust pipe 13 is greater on the other side (first cylinder (CYL1) side) than on one side (third cylinder (CYL3) side). As a result, the exhaust discharged from the other side can be guided downward on the downstream side of the air-fuel ratio sensor 14 due to the difference in the protruding amount on the mounting seat surface 14a.

Further, particularly in the present embodiment, a portion 135 positioned inward of the exhaust pipe 13 is provided on the inner surface of a portion on the one side (third cylinder (CYL3) side) of the bulging portion 134.
As a result, the amount of outward bulging on the inner surface of the exhaust pipe 13 at the portion of the bulging portion 134 on one side (the third cylinder (CYL3) side) is suppressed. For this reason, the inner surface of the exhaust pipe 13 on one side (the third cylinder (CYL3) side) of the bulging portion 134 and on the other side (the first cylinder (CYL1) side) of the bulging portion 134. The difference in the outward bulge amount can be further increased. As a result, the exhaust discharged from each cylinder is smoothly guided along the bulging portion 134 and smoothly guided downward on the downstream side of the air-fuel ratio sensor 14 by the portion where the bulging amount of the bulging portion 134 is small. Can be removed.

  Particularly in the present embodiment, one side is the side closer to the third cylinder in the direction in which the first cylinder, the second cylinder, and the third cylinder are in parallel, and the other side is the first in the direction in which the first cylinder is in parallel. The side closer to the cylinder. As a result, the exhaust discharged from the third cylinder flows along the bulging portion 134 and smoothly flows downward on the downstream side of the air-fuel ratio sensor 14 by the portion where the bulging portion 134 has a small bulging amount. It becomes possible to suppress obstruction of the flow of exhaust from the cylinder.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
In the above embodiment, the present invention is applied to the exhaust gas purification apparatus in which the exhaust manifold and the cylinder head are integrated. However, the present invention is not limited to this. For example, the present invention may be applied to an exhaust purification device in which the exhaust manifold is not integrated with the cylinder head but integrated with the downstream exhaust pipe.
Further, the configuration such as the shape of the bulging portion is not limited to the configuration such as the shape of the bulging portion 134 in the present embodiment.
Further, the inclination direction of the air-fuel ratio sensor may be reversed. In this case, the size of the diaphragm structure may be reversed.

DESCRIPTION OF SYMBOLS 1 ... Exhaust purification apparatus 11a-11f ... Exhaust port 12 ... Exhaust manifold (exhaust collection part)
13 ... Exhaust pipe 14 ... Air-fuel ratio sensor (exhaust sensor)
14a ... Mounting seat surface 15 ... Catalytic converter (exhaust gas purification means)
131a: upper surface wall 132 ... bent portion 134 ... bulged portion 135 ... portion located inward of exhaust pipe 151 ... opening X ... central axis Y ... perpendicular line

Claims (2)

Each exhaust port extending from each cylinder of the internal combustion engine is formed by collecting, and an exhaust collecting portion for collecting exhaust discharged from each cylinder;
An exhaust pipe that is provided on the downstream side of the exhaust collecting portion and guides the exhaust collected in the exhaust collecting portion to a downstream exhaust purification means;
An exhaust sensor attached to an upper surface wall of the exhaust pipe and disposed at a position where it can be seen in a cross-sectional view perpendicular to the central axis of the exhaust collection part at the connection part of the exhaust collection part and the exhaust pipe;
A bent portion provided in the exhaust pipe and bent downward on the downstream side of the exhaust sensor;
A bulging portion provided at the bending portion and bulging outward from the inlet of the exhaust gas purification means;
An exhaust purification device for an internal combustion engine comprising:
A mounting seat surface of the exhaust sensor is provided to protrude into the exhaust pipe,
The exhaust sensor is disposed so as to be inclined with respect to a vertical line orthogonal to the central axis in the vertical direction, and the area of the exhaust sensor on both sides of the vertical line in the cross-sectional view is larger on the one side than on the other side. Arranged to be smaller,
An exhaust gas purification apparatus for an internal combustion engine, wherein a bulge amount on the other side that bulges outward from the inlet of the exhaust gas purification means in the bulge portion is larger than a bulge amount on the one side.   The exhaust emission control device according to claim 1, wherein an amount of protrusion of the mounting seat surface to the inside of the exhaust pipe is larger on the other side than on the one side.

Images