WO2015046169A1

WO2015046169A1 - Exhaust pipe structure

Info

Publication number: WO2015046169A1
Application number: PCT/JP2014/075131
Authority: WO
Inventors: 高志井上
Original assignee: フタバ産業株式会社
Priority date: 2013-09-27
Filing date: 2014-09-22
Publication date: 2015-04-02
Also published as: JP2015068223A

Abstract

An exhaust pipe structure equipped with: an exhaust manifold having multiple branch pipes connected in correspondence with the multiple outlet ports of an internal combustion engine, and an outlet pipe provided on the downstream side of the multiple branch pipes and in which the exhaust gas flowing from the multiple branch pipes converges into a single flow; an exhaust gas sensor that detects abnormalities in the exhaust gas flowing in the outlet pipe; a tapered section which is provided on the downstream side of the outlet pipe, and the aperture area of the cross section of which increases in the downstream direction; a catalyst that purifies the exhaust gas supplied through the tapered section; a housing section which is provided on the downstream side of the tapered part, and which houses the catalyst; and an annular protruding part that protrudes from the inner circumferential surface of the tapered part toward the catalyst.

Description

Exhaust pipe structure

Cross-reference of related applications

This international application claims priority based on Japanese Patent Application No. 2013-2001966 filed with the Japan Patent Office on September 27, 2013. The entire contents are incorporated into this international application.

One embodiment of the present invention relates to an exhaust pipe structure.

For example, in an exhaust pipe structure as disclosed in Patent Document 1, an exhaust gas sensor (O ₂ sensor) is provided near the outlet of an exhaust manifold (aggregation part) in which two or more branch pipes (exhaust pipes) gather, A catalyst is provided downstream of the exhaust manifold. According to this type of exhaust pipe structure, the concentration of O _{2 in} the exhaust gas before being supplied to the catalyst is detected by the exhaust gas sensor.

Further, in the exhaust pipe structure of Patent Document 1, the exhaust gas flow path flowing from the exhaust manifold toward the catalyst side has a tapered portion (throat portion) whose cross-sectional opening area increases toward the downstream side. Yes. In addition, the center of the upstream end face of the catalyst is recessed so that the exhaust gas sensor does not directly detect the exhaust gas that bounces directly on the catalyst, thereby ensuring a sufficient distance between the exhaust gas sensor and the catalyst.

JP 2002-266635 A

∙ Some of the exhaust gas that hits the catalyst may flow back to the exhaust gas sensor along the inner peripheral surface of the taper. In this case, the exhaust gas sensor may detect the exhaust gas that has flowed back, and the detection accuracy of the exhaust gas may decrease.

In one aspect of the present invention, there is provided an exhaust pipe structure capable of suppressing as much as possible that exhaust gas that hits the catalyst and flows back to the exhaust gas sensor along the inner peripheral surface of the tapered portion reaches the exhaust gas sensor. It is desirable.

The exhaust pipe structure according to one aspect of the present invention includes an exhaust manifold, an exhaust gas sensor, a taper portion, a catalyst, a housing portion, and a protruding portion. The exhaust manifold collects a plurality of branch pipes connected to each of a plurality of outlet ports of the internal combustion engine and exhaust gas flowing from the plurality of branch pipes provided downstream of the plurality of branch pipes. It has an outlet piping. The exhaust gas sensor is provided in the vicinity of the outlet pipe and detects whether there is an abnormality in the exhaust gas flowing through the outlet pipe. The taper portion is provided on the downstream side of the outlet pipe, has a cylindrical shape, and an opening area of a cross section increases toward the downstream side. The catalyst purifies the exhaust gas supplied through the tapered portion. The accommodating portion is provided on the downstream side of the tapered portion and accommodates the catalyst. The protruding portion is annular and protrudes from the inner peripheral surface of the tapered portion toward the catalyst.

According to this aspect of the present invention, the exhaust gas that hits the catalyst and flows back to the exhaust gas sensor side along the inner peripheral surface of the tapered portion is caused by the annular protruding portion that protrudes from the inner peripheral surface of the tapered portion toward the catalyst. By being blocked, it becomes difficult to reach the exhaust gas sensor. Thereby, it is possible to suppress as much as possible the exhaust gas that hits the catalyst and flows back to the exhaust gas sensor side along the inner peripheral surface of the tapered portion, and to improve the detection accuracy of the exhaust gas. Can do.

In the exhaust pipe structure of one embodiment of the present invention, the protruding portion may be an end portion on the downstream side of the outlet pipe.
According to this aspect of the present invention, since the protrusion and the outlet pipe are integrated, the protrusion can be formed with a simple configuration.

In the exhaust pipe structure of one embodiment of the present invention, the protruding portion may be formed by bending the upstream end of the tapered portion inward.
According to this aspect of the present invention, since the protruding portion and the tapered portion are integrated, the protruding portion can be formed with a simple configuration.

In the exhaust pipe structure of one embodiment of the present invention, the protrusion may extend in parallel to the central axis of the catalyst.
According to this aspect of the present invention, the exhaust gas flowing from the upstream side of the projecting portion to the catalyst side is easily guided to the catalyst side along the projecting portion, and the exhaust gas stays inside the outlet pipe of the exhaust manifold. It becomes difficult. Thereby, the detection accuracy of the exhaust gas can be further improved.

Further, the exhaust pipe structure of one embodiment of the present invention may be a mesh-like member in which the protruding portion is provided on the inner peripheral surface of the tapered portion.
According to this aspect of the present invention, exhaust gas that hits the catalyst and flows back to the exhaust gas sensor side along the inner peripheral surface of the taper portion can be prevented from reaching the exhaust gas sensor as much as possible. The increase in the pressure loss of the exhaust gas flowing from the outlet pipe to the catalyst side can be suppressed as much as possible.

According to one aspect of the present invention, it is possible to suppress as much as possible that exhaust gas that hits the catalyst and flows back to the exhaust gas sensor along the inner peripheral surface of the tapered portion reaches the exhaust gas sensor.

The figure which represented typically the exhaust pipe structure of the 1st Embodiment of this invention. The perspective view of an exhaust pipe structure. The vertical side view of an exhaust pipe structure. IV-IV sectional drawing of FIG. FIG. 5 is a VV cross-sectional view of FIG. 3. FIG. 3 is an equivalent view of FIG. 3 showing an exhaust pipe structure of a second embodiment of the present invention. VII-VII sectional view of FIG. FIG. 3 is a view corresponding to FIG. 3 showing an exhaust pipe structure according to a third embodiment of the present invention.

DESCRIPTION OF SYMBOLS 11 ... Exhaust pipe structure 12 ... Internal combustion engine 13 ... Exhaust manifold 15 ... Branch pipe 16 ... Outlet pipe 19 ... Exhaust gas sensor (air-fuel ratio sensor)
21 ... Catalyst 23 ... Accommodating part 24 ... Taper part (upstream taper part)
26 ... Projection 31 ... Exhaust pipe structure 32 ... Projection 41 ... Exhaust pipe structure 42 ... Projection

<First Embodiment>
An exhaust pipe structure according to a first embodiment of the present invention will be described with reference to FIGS.
The exhaust pipe structure 11 shown in FIGS. 1 to 4 is a part of an exhaust pipe provided on the downstream side of an internal combustion engine 12 for automobiles (see FIG. 1), for example, on the downstream side of the exhaust pipe structure 11. An exhaust pipe connected to a silencer (not shown) is connected.

A plurality of, for example, four outlet ports (not shown) are formed in the internal combustion engine 12 in a line. Then, the exhaust gas generated by the internal combustion engine 12 is supplied to the exhaust pipe structure 11 through the outlet port.

The exhaust pipe structure 11 includes an exhaust manifold 13 and a catalytic converter 14.
The exhaust manifold 13 has, for example, a plurality of metal branch pipes 15 and, for example, a metal outlet pipe 16.

The branch pipe 15 is a pipe connecting the outlet port of the internal combustion engine 12 and the outlet pipe 16. Therefore, the number of branch pipes 15 corresponds to the number of outlet ports of the internal combustion engine 12, and the number of branch pipes 15 in this embodiment is four. Each branch pipe 15 has one end connected to each of the four outlet ports of the internal combustion engine 12 and the other end connected to the outlet pipe 16. In addition, as needed, each branch pipe 15 is demonstrated as the branch pipe 151, the branch pipe 152, the branch pipe 153, and the branch pipe 154 in order from the left side in FIG. 1, FIG. 2, and FIG.

A flange 17 is provided at an upstream end (hereinafter referred to as one end) of the branch pipe 15. The flange 17 has a shape that covers the entire outlet port of the internal combustion engine 12, for example, a long plate shape. As shown in FIG. 4, the flange 17 has an opening at a location corresponding to the outlet port of the internal combustion engine 12. An opening 18 is formed. If necessary, each opening 18 will be described as an opening 181, an opening 182, an opening 183, and an opening 184 in order from the left side in FIG. 4.

The flange 17 is attached to the internal combustion engine 12 as shown in FIG. 1 by a fastening member (not shown) such as a bolt. Moreover, as shown in FIG. 4, the branch pipe 15 and the flange 17 are joined by welding or the like. Specifically, the inside of the branch pipe 151 communicates with the opening 181, the inside of the branch pipe 152 communicates with the opening 182, the inside of the branch pipe 153 communicates with the opening 183, and the branch pipe 154. And the opening 184 communicate with each other.

The outlet pipe 16 is a pipe that collects a plurality of exhaust gases flowing from the four branch pipes 15 in this embodiment, and is provided on the downstream side of the branch pipe 15. In this embodiment, the four branch pipes 15 are formed in a cylindrical shape corresponding to the combined size of the lower ends.

The branch pipes 15 and the outlet pipes 16 may be integrated, or separate members may be joined together by welding or the like.
In the vicinity of the outlet pipe 16, more specifically, the position closest to the portion where the four branch pipes 15 of the outlet pipe 16 are combined, an exhaust gas sensor as shown in FIGS. A sensor 19 is provided. The exhaust gas sensor is a sensor that detects whether there is an abnormality in the exhaust gas flowing through the outlet pipe 16. Here, the air-fuel ratio sensor 19 used as the exhaust gas sensor is a sensor for detecting the air-fuel ratio of the exhaust gas flowing through the outlet pipe 16 as the presence or absence of abnormality of the exhaust gas. Although not described in detail, the output signal (abnormality presence / absence signal) of the exhaust gas sensor (air-fuel ratio sensor 19) is sent to a control circuit (not shown) that controls the fuel supply amount of the internal combustion engine.

The air-fuel ratio sensor 19 has a substantially cylindrical shape, and the end on the detection side, that is, the tip is located near the center inside the outlet pipe 16. The other end of the air-fuel ratio sensor 19 is connected to the control circuit (not shown) described above. In this embodiment, the air-fuel ratio sensor 19 is held by the mount 20 so that the axial direction of the air-fuel ratio sensor 19 substantially coincides with the radial direction of the outlet pipe 16.

In this embodiment, the air-fuel ratio sensor 19 is described as the exhaust gas sensor, but the present invention can also be applied to other sensors such as an oxygen sensor.
The catalytic converter 14 includes a catalyst 21 and a catalyst case 22 made of, for example, metal.

The catalyst 21 is provided on the downstream side of the outlet pipe 16 to purify the exhaust gas. For example, the catalyst 21 is a catalyst for oxidizing or reducing the exhaust gas. The catalyst 21 has a cylindrical shape, for example. The catalyst 21 is formed to be relatively large in order to ensure a sufficient area for purification. For example, the cross-sectional area in the axial direction of the catalyst 21 is set larger than the cross-sectional area in the axial direction of the outlet pipe 16. . In this embodiment, the diameter of the catalyst 21 is set larger than the diameter of the outlet pipe 16.

A large number of through holes (not shown) extending in the axial direction are formed inside the catalyst 21. And when exhaust gas passes the through-hole of the catalyst 21, purification | cleaning of exhaust gas is performed. The catalyst 21 is accommodated inside the accommodating portion 23 of the catalyst case 22.

The catalyst case 22 has an upstream end connected to the outlet pipe 16 of the exhaust manifold 13 and a downstream end connected to an exhaust pipe (not shown).
The catalyst case 22 has a housing part 23, an upstream taper part 24, and a downstream taper part 25.

The accommodating portion 23 has a cylindrical shape that accommodates the catalyst 21 therein, and is formed in a cylindrical shape corresponding to the outer shape of the catalyst 21 in this embodiment. Further, in this embodiment, the central axis of the accommodating portion 23 coincides with the central axis of the outlet pipe 16 so that the central axis of the catalyst 21 coincides with the central axis of the outlet pipe 16. Between the accommodating part 23 and the catalyst 21, the buffer member (not shown) for hold | maintaining the catalyst 21 in a predetermined position is provided.

The upstream taper portion 24 is provided on the downstream side of the outlet pipe 16, has a cylindrical shape, and has a tapered shape in which the opening area of the cross section increases toward the downstream side. In this embodiment, the upstream taper portion 24 has a conical taper shape so that the upstream end portion of the upstream taper portion 24 is connected to the outlet pipe 16 and the downstream end portion is connected to the accommodating portion 23. Yes. Thereby, the accommodating part 23 is provided downstream of the upstream taper part 24, and the exhaust gas supplied through the upstream taper part 24 is purified by the catalyst 21.

The housing portion 23 and the upstream taper portion 24 may be integrated, or separate members may be joined together by welding or the like. The integral part of the accommodating part 23 and the upstream taper part 24 is obtained, for example, by spinning. Further, when the housing portion 23 and the upstream taper portion 24 are formed of separate members, for example, the upstream taper portion 24 is formed in a cap shape, fitted into the housing portion 23, and joined by welding or the like.

The downstream taper portion 25 is provided on the downstream side of the housing portion 23, has a cylindrical shape, and has a tapered shape in which the opening area of the cross section decreases toward the downstream side. In this embodiment, the downstream tapered portion 25 is connected so that the upstream end of the downstream tapered portion 25 is connected to the accommodating portion 23 and the downstream end is connected to a cylindrical exhaust pipe (not shown). Conical taper. As a result, the exhaust gas that has passed through the through hole of the catalyst 21 accommodated in the accommodating portion 23 flows through the downstream taper portion 25 to the downstream exhaust pipe.

The housing part 23 and the downstream taper part 25 may be integrated, or separate members may be joined together by welding or the like. The integral part of the accommodating part 23 and the downstream taper part 25 is obtained by spinning, for example. Further, when the housing portion 23 and the downstream taper portion 25 are formed of separate members, for example, the downstream taper portion 25 is formed in a cap shape, fitted into the housing portion 23, and joined by welding or the like.

Here, a protrusion 26 is provided inside the upstream taper portion 24. The protruding portion 26 guides the exhaust gas that flows backward along the inner peripheral surface of the upstream taper portion 24 to the downstream side. The protruding portion 26 of this embodiment is an annular portion in which the downstream end of the outlet pipe 16 protrudes from the upstream end of the upstream tapered portion 24 to the inside of the upstream tapered portion 24. According to this configuration, the cylindrical protrusion 26 is formed at the upstream end of the upstream taper portion 24 so as to surround the periphery of the exhaust gas flowing out from the outlet pipe 16 in the circumferential direction.

In this embodiment, the central axis of the outlet pipe 16 and the central axis of the catalyst 21 coincide with each other, so that the protruding portion 26 extends in parallel to the central axis of the catalyst 21.
The axial length of the protruding portion 26 is appropriately set so that the exhaust gas flowing out from the inner peripheral side of the protruding portion 26 reaches the outer peripheral edge of the upstream end surface of the catalyst 21. That is, if the length of the protrusion 26 is too long, the exhaust gas flowing from the inner peripheral side of the protrusion 26 to the catalyst 21 is difficult to reach the entire upstream end surface of the catalyst 21, and the exhaust gas is only near the center of the catalyst 21. Will be purified. On the other hand, when the axial length of the protruding portion 26 is too short, it is difficult to sufficiently obtain the functions and effects of the present embodiment described later. Therefore, the length of the protruding portion 26 in the axial direction is set so that the operation and effect of the present embodiment described later can be sufficiently obtained.

According to the first embodiment, the following operations and effects are achieved.
Exhaust gas discharged from the outlet port of the internal combustion engine 12 flows through the predetermined branch pipe 15 of the exhaust manifold 13 to the outlet pipe 16. Exhaust gas that has flowed into the outlet pipe 16 is, as shown by arrows A in FIGS. And through the downstream taper portion 25, the exhaust pipe connected to the downstream side of the catalytic converter 14 is supplied.

According to this configuration, the air-fuel ratio sensor 19 detects whether or not the exhaust gas flowing through the outlet pipe 16 is in an abnormal state, in this embodiment, the air-fuel ratio of the exhaust gas.
Here, the direction of the flow of the exhaust gas that hits the catalyst 21 and flows back to the air-fuel ratio sensor 19 side along the inner peripheral surface of the upstream taper portion 24 is indicated by an arrow B. The exhaust gas flowing as shown by the arrow B is blocked by the protruding portion 26, so that it becomes difficult to reach the air-fuel ratio sensor 19 and is easily guided downstream.

As a result, the exhaust gas that hits the catalyst 21 and flows back to the air-fuel ratio sensor 19 along the inner peripheral surface of the upstream taper portion 24 can be prevented from reaching the air-fuel ratio sensor 19 as much as possible. Detection accuracy can be improved.

Further, since the protruding portion 26 is an end portion on the downstream side of the outlet pipe 16 and the protruding portion 26 and the outlet pipe 16 are integrated, the protruding portion 26 can be formed with a simple configuration.
Further, since the projecting portion 26 extends in parallel to the central axis of the catalyst 21, the exhaust gas flowing from the upstream side of the projecting portion 26 to the catalyst is easily guided along the projecting portion 26 to the catalyst 21 side, and the outlet The exhaust gas is less likely to stay inside the pipe 16. Thereby, the detection accuracy of the exhaust gas can be further improved.
<Second Embodiment>
An exhaust pipe structure according to a second embodiment of the present invention will be described with reference to FIGS. Of the members constituting the exhaust pipe structure 31 of the second embodiment, members substantially the same as those constituting the exhaust pipe structure 11 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Is omitted.

As shown in FIGS. 6 and 7, the exhaust pipe structure 31 is different in the structure of the protrusion 32 from the structure of the protrusion 26 of the first embodiment.
The projecting portion 32 of the exhaust pipe structure 31 is formed by bending the upstream end portion of the upstream taper portion 24 inward, and the end portion of the tip faces downstream. In this case, the protrusion 32 is provided in contact with the outer peripheral surface of the downstream end of the outlet pipe 16 and protrudes downstream from the end of the outlet pipe 16. Accordingly, the protruding portion 32 has a cylindrical shape concentric with the outlet pipe 16, and surrounds the outer periphery in the circumferential direction of the exhaust gas flowing out from the outlet pipe 16 at the upstream end of the upstream tapered portion 24. A cylindrical protrusion 32 is formed.

The protrusion 32 of this embodiment has the same function as the protrusion 26 of the first embodiment. Therefore, the exhaust pipe structure 31 of the second embodiment also has the same operations and effects as the exhaust pipe structure 11 of the first embodiment.

Moreover, since the protrusion part 32 is an upstream edge part of the upstream taper part 24 and the protrusion part 32 and the upstream taper part 24 are integral, the protrusion part 32 can be formed with a simple configuration.
<Third Embodiment>
An exhaust pipe structure according to a third embodiment of the present invention will be described with reference to FIG. Of the members constituting the exhaust pipe structure 41 of the third embodiment, substantially the same members as those constituting the exhaust pipe structure 11 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Is omitted.

As shown in FIG. 8, the exhaust pipe structure 41 differs in the structure of the protrusion part 42 from the structure of the protrusion part 26 of 1st Embodiment.
The projecting portion 42 of the exhaust pipe structure 41 is, for example, a metal mesh member, and has an annular shape as a whole. The size of the mesh gap is a size through which the exhaust gas can pass.

The outer peripheral surface of the protruding portion 42 is fixed to the inner peripheral surface of the upstream taper portion 24 by welding or the like.
The protruding portion 42 of this embodiment has the same function as the protruding portion 26 of the first embodiment. Therefore, the exhaust pipe structure 41 of the third embodiment also has the same operations and effects as the exhaust pipe structure 11 of the first embodiment.

Further, part of the exhaust gas flowing from the outlet pipe 16 of the exhaust manifold 13 to the catalyst 21 side passes through the mesh gap of the protruding portion 42, so the pressure loss of the exhaust gas flowing from the outlet pipe 16 to the catalyst 21 side. Can be suppressed as much as possible.
<Other embodiments>
The present embodiment is not limited to the above, and can take various forms within the technical scope of the present invention.

For example, in the present embodiment, the internal combustion engine 12 has been described as having four outlet ports, but the number of outlet ports may be other than four.
You may combine suitably each protrusion part of the protrusion part 26 of 1st Embodiment, the protrusion part 32 of 2nd Embodiment, and the protrusion part 42 of 3rd Embodiment.

The exhaust gas sensor (air-fuel ratio sensor 19) has been described as being provided at a position closest to the portion of the outlet pipe 16 where the four branch pipes 15 are combined, but the present invention is not limited to this. Any position where an action / effect can be obtained may be used. For example, the position of the exhaust gas sensor may be from the portion where the branch pipes 15 are combined to the catalyst 21, more specifically, the upstream taper portion 24.

The protruding portion 26 of the first embodiment may be formed as a member different from the outlet pipe 16 and fixed to the outlet pipe 16 by welding or the like.
The protruding portion 32 of the second embodiment may be formed by a member different from the upstream taper portion 24 and fixed to the upstream taper portion 24 by welding or the like.

Moreover, the protrusion part of this invention is not limited to the shape extended in parallel with respect to the central axis of the catalyst 21, For example, it is good also as a shape which spreads as it goes downstream.
In addition, the said structure is only an example, You may change a shape, a number, material, a joining method, etc. suitably in the range which does not deviate from the meaning of invention. For example, the exhaust manifold 13 and the catalyst case 22 may be formed from a resin or the like. Further, the central axis of the accommodating portion 23, the central axis of the catalyst 21, and the central axis of the outlet pipe 16 do not have to coincide with each other.

Claims

A plurality of branch pipes connected corresponding to each of a plurality of outlet ports of the internal combustion engine, and an outlet provided downstream of the plurality of branch pipes and collecting exhaust gases flowing from the plurality of branch pipes into one An exhaust manifold with piping;
An exhaust gas sensor for detecting the presence or absence of abnormality of the exhaust gas flowing through the outlet pipe;
A taper portion provided on the downstream side of the outlet pipe, having a cylindrical shape, and having an opening area of a cross section that increases toward the downstream side;
A catalyst for purifying the exhaust gas supplied through the tapered portion;
A receiving portion that is provided on the downstream side of the tapered portion, and that contains the catalyst;
An annular protrusion protruding from the inner peripheral surface of the tapered portion toward the catalyst;
Exhaust pipe structure equipped with.
The exhaust pipe structure according to claim 1, wherein the protrusion is an end portion on the downstream side of the outlet pipe.
The exhaust pipe structure according to claim 1 or 2, wherein the protruding portion is formed by bending an upstream end portion of the tapered portion inward.
The exhaust pipe structure according to any one of claims 1 to 3, wherein the protrusion extends in parallel to a central axis of the catalyst.
The exhaust pipe structure according to claim 1, wherein the protrusion is a mesh-like member provided on an inner peripheral surface of the tapered portion.