JP2018091152A - Exhaust system structure for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust system structure capable of improving the exhaust emission control ability of an exhaust emission control device provided in the outlet of a supercharger.SOLUTION: In the exhaust system structure for an internal combustion engine in which the exhaust emission control device is provided in the outlet of the supercharger, the upstream side end of an exhaust emission control part of the exhaust emission control device is located on the upside in the vertical direction further than the lower end in the vertical direction of the outlet of the supercharger, and the downstream side end of the exhaust emission control part is located on the downside in the vertical direction further than the lower end in the vertical direction of the outlet of the supercharger.SELECTED DRAWING: Figure 2

Description

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

  2. Description of the Related Art Conventionally, an exhaust system structure provided with an exhaust purification device (a catalyst, a filter, etc.) that is provided in an exhaust system of an internal combustion engine and purifies exhaust gas discharged from the internal combustion engine is known.

  Patent Document 1 discloses an exhaust system structure in which a catalytic converter is provided at the outlet of a turbocharger. In the exhaust system structure described in Patent Document 1, a catalytic converter is disposed at the outlet of the turbocharger via a straight pipe and a bent pipe.

JP 2003-49640 A

  By the way, in recent years, it has been desired to improve the exhaust gas purification capability in the exhaust gas purification apparatus by strengthening the exhaust gas regulations.

  An object of the present invention is to provide an exhaust system structure capable of improving the exhaust gas purification ability in an exhaust purification device.

  An exhaust system structure of an internal combustion engine according to the present invention is an exhaust system structure of an internal combustion engine in which an exhaust purification device is provided at an outlet of a supercharger, and an upstream end of the exhaust purification unit of the exhaust purification device is the supercharger. It is located above the lower end in the vertical direction of the outlet of the turbocharger in the vertical direction, and the downstream end of the exhaust gas purification unit is located below the lower end in the vertical direction of the outlet of the supercharger in the vertical direction To do.

  According to the exhaust system structure of the internal combustion engine of the present invention, the exhaust purification device provided at the outlet of the supercharger can be enlarged, and the exhaust gas purification capability of the exhaust purification device can be improved.

Schematic showing an exhaust system according to an embodiment of the present invention. Partial enlarged view of FIG. AA sectional view of FIG. BB sectional view of FIG. Schematic showing how exhaust gas diffuses in the diffusion section Partial enlarged view of the exhaust system according to the reference example

  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. FIG. 2 is a partially enlarged view of FIG. 1 and 2, the X axis, the Y axis, and the Z axis are drawn. In the following description, the left-right direction in FIGS. 1 and 2 is referred to as the X direction or the vehicle front-rear direction, the right direction is referred to as “+ X direction” or “forward”, and the left direction is referred to as “−X direction” or “rearward”.

  1 and 2 are referred to as the Y direction or the vehicle up-down direction, the upward direction is referred to as “+ Y direction” or “upper side”, and the downward direction is referred to as “−Y direction” or “lower side”. In the following description, “upper side” and “lower side” are used to mean “upper side in the vertical direction” and “lower side in the vertical direction”, respectively.

1 and 2, the direction perpendicular to the paper surface is referred to as the Z direction or the vehicle width direction, the front direction is referred to as “+ Z direction” or “right side”, and the back direction is referred to as “−Z direction” or “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 FIGS. 1 and 2, the exhaust system 1 includes an exhaust manifold 3 provided on the right side of the engine 2, a turbocharger 4 connected to a collective portion of the exhaust manifold 3, and a turbocharger 4. An upstream exhaust passage 5, an aftertreatment device 6, and a downstream exhaust passage 7. In the case of the present embodiment, the above-described members are arranged on the right side of the engine 2. However, the arrangement of the above 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 of the turbocharger 4 are comprehensively determined based on the shape, size, installation location, and the like of the aftertreatment device 6. 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 constituted by an internal space of a hollow tubular tube 8. The pipe 8 serves as a flow path for allowing the exhaust gas flowing into the internal space from the upstream opening to flow along the extending direction of the pipe 8 (that is, the direction of the axis 8a) and to flow out from the downstream opening. It has a function. In the case of this configuration example, the shaft 8 a corresponds to the central axis of the tube 8.

  The upstream end of the pipe 8 is connected to the exhaust gas outlet 4a. On the other hand, the downstream end of the pipe 8 is fixed to the upstream end of a case 10 (described later) of the post-processing device 6. The extending direction (that is, the direction of the shaft 8a), the length, and the hollow cross-sectional shape of the straight tube 8 are comprehensive based on the direction of the exhaust gas outlet 4a, the position of the DOC 11 (described later) in the aftertreatment device 6, and the like. Determined.

  In addition, the hollow cross-sectional shape of the pipe | tube 8 means the cross section (cross-sectional shape regarding the virtual plane orthogonal to the axis | shaft 8a) of the internal space defined by the internal peripheral surface of the pipe | tube 8. FIG. In other words, the outer shape (the shape of the outer peripheral edge) of the hollow cross-sectional shape of the tube 8 matches the cross-sectional shape of the inner peripheral surface of the tube 8 with respect to the virtual plane orthogonal to the axis 8a.

  The extending direction of the 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, the pipe 8 is extended in the same −X direction as the exhaust gas outlet 4 a as shown in FIGS. 1 and 2. Moreover, the hollow cross-sectional shape of the pipe 8 is the same circle as the shape of the exhaust gas outlet 4a except for a part on the downstream side.

  The reason why the hollow cross-sectional shape of the pipe 8 is the same as that of the exhaust gas outlet 4a is that the flow rate of the exhaust gas flowing into the pipe 8 from the turbocharger 4 is kept high without being reduced as much as possible. It is for making it flow out to DOC11. The length of the 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 exhaust gas flow rate.

  As described above, the upstream end of the aftertreatment device 6 that is an exhaust purification device is connected to the downstream end of the pipe 8. The post-processing device 6 includes a tubular case 10 in which a DOC 11 (corresponding to the “exhaust gas purification unit” of the present invention) and a diesel particulate filter (DPF) 12 for purifying exhaust gas are accommodated. The details of the structure connecting the downstream end of the pipe 8 and the upstream end of the post-processing device 6 will be described later.

  The case 10 is fixed to the engine 2 via a bracket 14 that is fixed to the outer peripheral surface of the case 10 by welding. Specifically, in the case of this embodiment, the bracket 14 is attached to the second bracket 15 protruding from the engine 2 (in the case of this embodiment, protruding to the right from the engine 2) (in the case of this embodiment). , Mounted from the front).

  The DOC 11 and the DPF 12 are held in the case 10 with an inorganic mat 13. 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 is tilted three-dimensionally with respect to the shaft 8a. Here, for easy understanding, as shown in FIG. 2, the shaft 11a extends in the −Y direction.

  The shaft 11a extends in a direction perpendicular to the upstream end surface 11b and the downstream end surface 11c of the DOC 11. That is, the upstream end surface 11b and the downstream end surface 11c of the DOC 11 extend on the XZ plane, and the transverse cross-sectional shape of the DOC 11 (the cross-sectional shape related to the virtual plane orthogonal to the axis 11a) is the upstream end surface 11b and the downstream end surface. It becomes the same shape as the side end face 11c.

  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 is formed in a column shape having a shaft 12a. In this embodiment, the shaft 12a corresponds to the central axis of the DPF 12. Further, as shown in FIG. 2, the shaft 12a coincides with the shaft 11a. That is, the shaft 12a extends in the −Y direction.

  The shaft 12a extends in a direction perpendicular to the upstream end surface 12b and the downstream end surface 12c of the DPF 12. That is, the upstream end face 12b and the downstream end face 12c of the DPF 12 extend on the XZ plane, and the transverse cross-sectional shape of the DPF 12 (the cross-sectional shape related to the virtual plane orthogonal to the axis 12a) is the upstream end face 12b and the downstream end face. It becomes the same shape as the side end face 12c.

  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 post-processing device 6. The exhaust gas purified by the post-processing device 6 passes through the downstream exhaust passage 7 and is led out to the outside. The downstream side of the downstream side exhaust passage 7 extends linearly in the −X direction, and the exhaust gas is led backward from the rear end of the downstream side exhaust passage 7.

  Next, details of the positional relationship between the exhaust gas outlet 4a of the turbocharger 4 and the DOC 11 will be described. FIG. 2 shows a central axis 4 b of the exhaust gas outlet 4 a of the turbocharger 4. The central shaft 4b is an example of an axis line of the turbocharger 4. As shown in FIG. 2, the upstream end surface 11b of the DOC 11 is located above the central axis 4b. Further, the downstream end face 11c of the DOC 11 is located below the center axis 4b.

  Next, the structure of the pipe 8 and the details of the structure connecting the downstream end of the pipe 8 and the upstream end of the post-processing device 6 will be described. In FIG. 2, the flow of the exhaust gas passing through the pipe 8 and the DOC 11 is indicated by a broken line. FIG. 3 shows a cross section taken along the line AA of FIG. FIG. 4 shows a BB cross section of FIG. Further, in FIG. 5, when the upstream end surface 11b of the DOC 11 is viewed from the upper side, the exhaust gas diffuses from the downstream end portion of the bent portion 8b (described later) to the upstream end surface 11b by the diffusion portion 8c (described later). The state of doing is shown.

  As shown in FIG. 2, the tube 8 has a bent portion 8b and a diffusing portion 8c. The bent portion 8b extends from the exhaust gas outlet 4a of the turbocharger 4 in the -Y direction while being bent in the + Y direction, and is further bent in the -Y direction. Moreover, the diffusion part 8c is a part that spreads in the vehicle width direction and rearward from the downstream side end part (downstream side of the position of the BB cross section) of the bent part 8b. The axis 8a of the tube 8 coincides with the axis of the bent portion 8b. Therefore, in the following description, the “axis 8a” means the axis of the tube 8 and the axis of the bent portion 8b.

  The bent portion 8b has a function of guiding the exhaust gas discharged from the exhaust gas outlet 4a in the direction of the shaft 8a. The hollow cross-sectional shape at the position of the AA cross section of the bent portion 8b is a circle as shown in FIG. Further, the bent portion 8b gradually expands in the vehicle width direction while curving in the -Y direction. Therefore, the hollow cross-sectional shape in the position of the BB cross section of the bending part 8b becomes a substantially ellipse which has a long axis in a vehicle width direction, as shown in FIG.

  The diffusion part 8c has a function of guiding a part of the exhaust gas that has circulated through the bent part 8b in a direction away from the shaft 8a. The diffusion portion 8c includes a peripheral wall portion 8d and a lid portion 8e that closes the upper side of the peripheral wall portion 8d. A surface of the lid portion 8e that faces the upstream end surface 11b forms a facing surface 8f.

  A gap through which exhaust gas passes is provided between the upstream end face 11b and the facing face 8f. In the present embodiment, the lid portion 8e is provided in parallel to the upstream end surface 11b, and the gap between the upstream end surface 11b and the facing surface 8f is constant. The lid portion 8e may be tapered, and the gap between the upstream end surface 11b and the facing surface 8f may be made smaller toward the outer diameter side.

<Effect of this embodiment>
As described above, according to the exhaust system structure of the internal combustion engine according to the present embodiment, the upstream end surface 11b of the DOC 11 is located above the central axis 4b of the exhaust gas outlet 4a of the turbocharger 4. The downstream end face 11c is located below the central axis 4b.

  Thereby, the axial direction length of DOC11 can be lengthened, without changing the position of the up-down direction of the downstream end surface of DOC11. Therefore, the volume of the DOC 11 can be increased, and the exhaust gas purification ability can be improved.

  Further, according to the exhaust system structure of the internal combustion engine according to the present embodiment, the pipe 8 is curved in the + Y direction while extending in the −X direction from the exhaust gas outlet 4a of the turbocharger 4, and further in the −Y direction. There is a bent portion 8b that is curved, and a diffusion portion 8c that is provided at the downstream end of the bent portion 8b and diffuses the exhaust gas that has passed through the bent portion 8b to the upstream end surface 11b of the DOC 11.

  The effect of having such a configuration of the tube 8 will be described with reference to a reference example. As shown in FIG. 6, the pipe 18 in the exhaust system structure of the internal combustion engine according to the reference example does not include a diffusing portion, and gradually increases in diameter toward the upstream end surface 11 b of the DOC 11.

  The exhaust system structure of the internal combustion engine according to the reference example is different from the exhaust system structure of the internal combustion engine according to the above embodiment only in that the shape of the pipe 18 is different from the shape of the pipe 8, and the other structures are the same as those described above. Since it is the same as the structure of embodiment, detailed description is abbreviate | omitted.

  In the case of the exhaust system structure of the internal combustion engine according to the reference example, the pipe 18 does not include a diffusing portion and gradually increases in diameter toward the upstream end face 11b of the DOC 11, so that the flow of exhaust gas is as shown in FIG. As shown in FIG. 6, it concentrates on a part (-X direction side) of DOC11. As a result, the amount of exhaust gas flowing into the DOC 11 is biased.

  On the other hand, in the case of the present embodiment, the pipe 8 is provided with a diffusion portion 8c that diffuses the exhaust gas that has passed through the bent portion 8b to the upstream end surface 11b of the DOC 11 at the downstream end portion of the bent portion 8b. .

  Thereby, a part of exhaust gas which reached the upstream end surface 11b of the DOC 11 can be diffused in a direction away from the shaft 8a along the upstream end surface 11b. Therefore, the deviation of the inflow amount of the exhaust gas to the DOC 11 can be suppressed, and the DOC 11 can be used effectively.

<Modification>
In the above embodiment, the upstream end surface 11b of the DOC 11 is positioned above the central axis 4b of the exhaust gas outlet 4a of the turbocharger 4, and the downstream end surface 11c is positioned below the central axis 4b. However, the present invention is not limited to this.

  The upstream end surface 11b of the DOC 11 may be positioned above the lower end of the exhaust gas outlet 4a of the turbocharger 4, and the downstream end surface 11c may be positioned below the lower end of the exhaust gas outlet 4a. This also makes it possible to increase the axial length of the DOC 11 without changing the vertical position of the downstream end face of the DOC 11. Therefore, the volume of the DOC 11 can be increased, and the exhaust gas purification ability can be improved.

  Moreover, although the case where it applied to a vehicle was mentioned as an example and demonstrated in the said embodiment, it is not limited to this. The exhaust system structure of the present invention may be applied to an internal combustion engine in a state before being mounted on a vehicle, or may be applied to an internal combustion engine that is not assumed to be mounted on a vehicle.

  Moreover, in the said embodiment, although the pipe | tube 8 was extended back, this invention is not restricted to this, For example, according to the installation place of the post-processing apparatus 6, etc., you may be extended ahead.

  Moreover, although the said embodiment demonstrated what used DOC11 as a catalyst, it is not limited to this. As the catalyst, a lean NOx trap catalyst (LNT) may be used instead of DOC.

  Moreover, although the said embodiment demonstrated what provided DPF12 in the downstream of DOC11 of case 10, it is not limited to this. Only the DOC 11 may be carried on the case 10. Various exhaust purification sections (for example, SCR, SDPF having an SCR function, various slip catalysts, etc.) may be provided on the downstream side of the DOC 11.

  The exhaust system structure of the internal combustion engine of the present invention is useful as an exhaust gas aftertreatment device that requires a large volume of the exhaust purification unit.

DESCRIPTION OF SYMBOLS 1 Exhaust system 2 Engine 3 Exhaust manifold 4 Turbocharger 4a Exhaust gas outlet 4b Center shaft 5 Upstream exhaust passage 6 Post-processing device 7 Downstream exhaust passage 8, 18 Pipe 8a, 11a, 12a Shaft 8b Bending portion 8c Diffusion portion 8d peripheral wall 8e lid 8f facing surface 10 case 11 DOC
11b, 12b Upstream end face 11c, 12c Downstream end face 12 DPF
13 Inorganic mat 14 Bracket 15 Second bracket

Claims (3)

An exhaust system structure of an internal combustion engine provided with an exhaust purification device at the outlet of the supercharger,
The upstream side end of the exhaust gas purification unit of the exhaust gas purification device is located above the lower end in the vertical direction of the outlet of the supercharger in the vertical direction, and
The downstream end of the exhaust gas purification unit is located below the vertical lower end of the supercharger outlet in the vertical direction,
The exhaust system structure of an internal combustion engine. An upstream end portion of the exhaust gas purification unit of the exhaust gas purification device is located above the turbocharger in the vertical direction, and
The downstream end of the exhaust gas purification unit is positioned below the axis of the supercharger in the vertical direction;
The exhaust system structure of the internal combustion engine according to claim 1. The exhaust passage from the supercharger outlet to the exhaust gas purification device has a bent portion that curves downward after being curved upward from the axial direction of the supercharger outlet,
The downstream end portion of the bent portion is provided with a diffusion portion that diffuses the exhaust gas that has passed through the bent portion to the upstream end surface of the exhaust purification portion,
The exhaust system structure of the internal combustion engine according to claim 1 or 2.

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