JP2006283586A - Exhaust pipe structure of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain a deviation of a flow speed of exhaust gas, in a catalyst for purifying the exhaust gas exhausted from an engine. <P>SOLUTION: This exhaust pipe structure has exhaust gas passages 13, 14 and 15 for flowing the exhaust gas exhausted from the engine 11, the catalyst 19 for purifying the exhaust gas, and an assembly part 16 having one end opening part 17 connected to outlets 13A, 14A and 15A of exhaust gas passages 13, 14 and 15 and having the other end opening part 18 connected to an inlet 19A of the catalyst 19. The exhaust gas passages 13, 14 and 15 and the catalyst 19 are arranged so that the axes 13C, 14C and 15C of the exhaust gas passages 13, 14 and 15 cross with the axis 19C of the catalyst 19, and comprise a projection part 21 formed in the assembly part 16 in a crossing place of the axes 13C, 14C and 15C of the exhaust gas passages 13, 14 and 15 and the axis 19C of the catalyst 19. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust pipe structure of an engine.

The engine exhaust system is generally provided with a catalyst for purifying exhaust gas. In recent years, a technology has been developed in which a catalyst is connected directly to the downstream side of the engine exhaust manifold so that the exhaust gas can be supplied to the catalyst at a high temperature before the temperature of the exhaust gas discharged from the engine decreases. Has been put to practical use.
This catalyst is a catalyst called a manifold direct-type catalytic converter (hereinafter simply referred to as MCC (Manifold Catalytic Converter)), and can be activated immediately after the engine is started so that the exhaust gas performance can be improved immediately after the engine is started. It has become.

In addition, the following patent document 1 is mentioned as a literature in which the technique about such MCC was disclosed.
JP-A-8-21231

However, there is a problem that the exhaust gas flow rate is uneven in the catalyst, and the exhaust gas flow rate locally increases or decreases. In particular, when a large-diameter MCC is provided in an exhaust passage connected to an engine having a small exhaust port diameter (for example, an engine having a small displacement), the above-described problem is conspicuous.
And when such a deviation in the exhaust gas flow velocity occurs, the exhaust gas circulates through only a part of the catalyst, and only that part of the catalyst is constantly heated, thereby causing local deterioration of the catalyst. Will be invited.

Further, the fact that exhaust gas circulates only in a part of the catalyst means that exhaust gas purification is not performed as a whole catalyst, but purification is performed only in the catalyst in the part where the exhaust gas circulates, and in other parts. This means that the purification is not performed, and the purification performance of the catalyst as a whole cannot be fully utilized effectively.
Such a problem will be described with reference to FIGS. 8 to 11 by taking a technique created in the process of creating the present invention as an example. 8 is a schematic top view of the exhaust manifold 100, and FIG. 9 is a schematic cross-sectional view taken along line AA in FIG. 10 is a schematic diagram showing the flow velocity distribution of the exhaust gas in the concentrating portion 106 in the BB cross section of FIG. 9, and FIG. 11 shows the flow velocity distribution of the exhaust gas in the catalyst 109 in the CC cross section of FIG. It is a schematic diagram.

As shown in FIGS. 8 and 9, the exhaust manifold 100 collects exhaust gases discharged from three exhaust ports (not shown) in the three-cylinder engine 101 and sends them to the exhaust pipe 102.
The exhaust manifold 100 is provided with a first branch pipe 103, a second branch pipe 104, a third branch pipe 105, and a collecting portion 106.

  The first branch pipe 103, the second branch pipe 104, and the third branch pipe 105 are configured to send exhaust gas discharged from the exhaust ports of the engine 101 to the aggregation unit 106. The inlets 103A, 104A, and 105A of the first to third branch pipes 103, 104, and 105 are connected to the exhaust ports of the engine 101, respectively. The outlets 103B, 104B, and 105B of the first to third branch pipes 103, 104, and 105 are all connected to the aggregation unit 106.

A branch pipe side opening 107 and an exhaust pipe side opening 108 are formed in the concentrating part 106, and exhaust gas sent from the first to third branch pipes 103, 104, 105 can be collected. Yes.
Further, outlets 103B, 104B, and 105B of the first, second, and third branch pipes 103, 104, and 105 are connected to the branch pipe side opening 107, and the exhaust pipe side opening 108 is connected to An inlet 102A of the exhaust pipe 102 is connected. Further, a catalyst 109 is disposed in the exhaust pipe 102.

9, the first to third branch pipes 103, 104, 105 (only the first branch pipe 103 is shown in FIG. 9) and the catalyst 109 are the first to third branch pipes. The axial lines 103C, 104C, and 105C (only the first branch pipe axis 103C is shown in FIG. 9) and the axis 109C of the catalyst 109 are arranged so as to be substantially orthogonal to each other.
Here, FIG. 10 shows the flow velocity distribution of the exhaust gas in the concentrating portion 106 in the BB cross section of FIG. 9, and FIG. 11 shows the flow velocity distribution of the exhaust gas in the catalyst 109 in the CC cross section of FIG. Note that the flow velocity distribution diagrams shown in FIGS. 10 and 11 show a case where exhaust gas is sent from the first branch pipe 103 to the concentrating unit 106. Further, in FIGS. 10 and 11, the dark color portion indicates that the flow velocity is high, and the light color portion indicates that the flow velocity is low.

That is, as shown in FIG. 10, the flow rate of the exhaust gas sent from the first branch pipe 103 into the aggregation unit 106 is fast near the outer periphery in the aggregation unit 106 and is substantially zero near the center. This is considered to be because the exhaust gas flows along the outer periphery of the gathering portion 106 as indicated by arrows in FIG.
Further, as indicated by reference numeral P ₁₀₉ in FIG. 11, a portion having an extremely low flow velocity is generated in the catalyst 109. For this reason, the catalyst 109 in the portion P ₁₀₉ does not function sufficiently and purifies exhaust gas. It turns out that it does not contribute to.

  In addition, in the technique demonstrated using FIGS. 8-11, the method of moving the catalyst 109 to the downstream in the exhaust pipe 102 and aiming at the stirring of exhaust gas is also considered. However, according to this method, although the exhaust gas is expected to be stirred to some extent, the distance until the exhaust gas discharged from the engine 101 reaches the catalyst 109 becomes long. For this reason, the original effect of MCC, in which exhaust gas is supplied to the catalyst 109 before the temperature of the exhaust gas lowers and the catalyst 109 is activated early, cannot be sufficiently obtained, and the exhaust gas purification efficiency is reduced. turn into.

On the other hand, according to the technique disclosed in Patent Document 1, the exhaust gas discharged from the exhaust manifold is deflected so as to flow spirally. In this method, the flow direction of the exhaust gas supplied to the MCC is aligned. Therefore, the deviation of the flow rate of the exhaust gas cannot be sufficiently suppressed in the MCC.
The present invention has been devised in view of such a problem, and an object of the present invention is to provide an engine exhaust pipe structure capable of suppressing a deviation in the flow rate of exhaust gas in a catalyst.

  In order to achieve the above object, an exhaust pipe structure for an engine according to the present invention (Claim 1) includes an exhaust gas passage through which exhaust gas discharged from the engine flows, a catalyst for purifying the exhaust gas, and an opening at one end thereof. And an exhaust pipe structure of an engine having an opening at the other end connected to an inlet of the catalyst, wherein the exhaust gas passage and the catalyst are connected to an axis of the exhaust gas passage and the exhaust gas passage. The catalyst is disposed so as to intersect with the axis of the catalyst, and the collecting portion includes a protrusion formed at a position where the axis of the exhaust gas passage intersects with the axis of the catalyst.

According to a second aspect of the present invention, there is provided the exhaust pipe structure of the engine of the present invention according to the first aspect, wherein the protrusion includes an axially orthogonal section of the exhaust gas passage projected along the axis of the exhaust gas passage. It is characterized by being formed.
According to a third aspect of the present invention, there is provided an exhaust pipe structure for an engine according to the present invention, wherein the collecting portion is an outer peripheral wall that forms the other end opening connected to the inlet of the catalyst. And a tip wall that covers the tip of the outer peripheral wall, and the protrusion is formed so as to protrude from the other end opening side of the tip wall.

According to a fourth aspect of the present invention, there is provided the exhaust pipe structure of the engine according to the first aspect of the present invention, wherein the projection has a conical shape whose top is raised toward the opening of the other end. It is characterized by being formed.
The exhaust pipe structure of the engine of the present invention according to claim 5 is the content of claim 4, wherein the exhaust gas passage and the catalyst have an obtuse angle between the axis of the exhaust gas passage and the axis of the catalyst. In addition, the peripheral surface of the projecting portion formed in the conical shape is disposed at an obtuse angle with respect to the axis of the exhaust gas passage.

The exhaust pipe structure of the engine of the present invention according to claim 6 is the content of any one of claims 1 to 5, wherein a plurality of the exhaust gas passages are provided, and the central axis of the projection is It arrange | positions so that it may be located in the intersection of the axis line of several waste gas passage.
According to a seventh aspect of the present invention, in the exhaust pipe structure of the engine of the present invention, the peripheral surface of the projection on the side of the exhaust passage is relative to any axis of the plurality of exhaust gas passages. Is also formed to intersect at the same angle.

According to the exhaust pipe structure of the engine of the present invention, the exhaust gas supplied to the catalyst is agitated, whereby the deviation of the flow rate of the exhaust gas in the catalyst can be suppressed. As a result, the entire catalyst can be effectively used, exhaust gas performance can be improved, and durability of the catalyst can be improved. (Claim 1)
In addition, the exhaust gas flowing through the exhaust gas passage is surely applied to the protrusions, whereby stirring of the exhaust gas can be promoted. (Claim 2)
In addition, by causing the exhaust gas to collide with the protrusion and the outer peripheral wall, the exhaust gas can be allowed to flow into the catalyst after being well stirred, so that it is possible to effectively suppress the deviation of the exhaust gas flow velocity in the catalyst. it can. (Claim 3)
Moreover, exhaust gas can be rapidly guided with respect to a catalyst, stirring exhaust gas by applying exhaust gas to a cone-shaped projection part. In addition, the processability of the protrusion can be improved. (Claim 4)
Moreover, by setting the intersection angle between the axis of the catalyst and the axis of the exhaust gas flow path to be an obtuse angle, and setting the intersection angle of the peripheral surface of the protrusion and the axis of the exhaust gas passage to be an obtuse angle, While promoting the stirring of the exhaust gas, it is possible to guide the exhaust gas to quickly flow into the catalyst. (Claim 5)
In addition, the exhaust gas flowing through the plurality of exhaust gas passages can be reliably applied to the protrusions and stirred. (Claim 6)
In addition, the exhaust gas flowing through a plurality of exhaust gas passages collide with the protrusions under the same conditions, respectively, so that each exhaust gas is agitated in the same manner so that the exhaust gas flow rate does not become uneven in the catalyst. Can do. (Claim 7)

  Hereinafter, an engine exhaust pipe structure according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic top view showing the exhaust manifold, and FIG. 2 is a schematic view of FIG. 1 showing the exhaust manifold. FIG. 3 is a schematic external view showing the exhaust manifold, FIG. 4 is a schematic view showing the flow of exhaust gas flowing through the exhaust manifold shown in FIG. 1, and FIG. 5 is an exhaust manifold shown in FIG. FIG. 6 is a schematic diagram showing the exhaust gas velocity distribution in the exhaust manifold, and FIG. 7 is a schematic diagram showing the exhaust gas velocity distribution in the catalyst.

As shown in FIGS. 1, 2, and 3, an exhaust manifold 10 is provided in the three-cylinder engine 11, and exhaust gases discharged from three exhaust ports (not shown) are gathered to the exhaust pipe 12. Can be sent out.
The exhaust manifold 10 is provided with a first branch pipe (exhaust gas passage) 13, a second branch pipe (exhaust gas passage) 14, a third branch pipe (exhaust gas passage) 15, and a collecting portion 16.

These first, second and third branch pipes 13, 14 and 15 have respective inlets 13A, 14A and 15A connected to exhaust ports of the engine 11, respectively, while the respective outlets 13B, 14B and 15B All are connected to the collecting section 16. Thereby, the exhaust gas discharged from each exhaust port of the engine 11 can be sent to the collecting portion 16.
Further, the collecting portion 16 is formed with a branch pipe side opening 17 and an exhaust pipe side opening 18. Among these, the branch pipe side opening 17 is connected to the outlets 13B, 14B, 15B of the first, second and third branch pipes 13, 14, 15 and the exhaust pipe side opening 18 is connected to the outlet pipe side opening 18. The inlet 12A of the exhaust pipe 12 is connected. A catalyst 19 is disposed in the exhaust pipe 12.

The catalyst 19 can purify the exhaust gas discharged from the engine 11. The catalyst 19 is a manifold direct catalytic converter (MCC), and the activation of the catalyst 19 can be achieved early by supplying the exhaust gas at a high temperature before the temperature of the exhaust gas decreases. ing.
In the vertical sectional view as shown in FIG. 2, each branch pipe 13, 14, 15 (only the first branch pipe 13 is shown in FIG. 2) and the catalyst 19 are connected to the axis 13C, 14C, 15C of each branch pipe. The angle θ ₁ formed by the axis 19C of the catalyst 19 (only the axis 13C of the first branch 13 is shown in FIG. 2) intersects at about 100 degrees. In addition, each branch pipe axis line 13C, 14C, 15C means the axis line in the part connected to the gathering part 16 among each branch pipe 13,14,15.

Here, the angle θ ₁ formed between each branch pipe axis 13C, 14C, 15C and the axis 19C of the catalyst 19 is not a right angle or an acute angle, but an obtuse angle (about 100 degrees). This is a device for facilitating introduction of exhaust gas flowing through the pipes 13, 14, and 15 into the catalyst 19.
In this way, the collecting portion 16 is arranged in the downward direction in FIG. 2, that is, the catalyst 19 is disposed in the exhaust gas sent to the collecting portion 16 in a substantially horizontal direction through the branch pipes 13, 14, 15. By changing the direction of the flow in a certain direction, the catalyst 19 can be guided.

Further, the collecting portion 16 forms the other end opening 18 connected to the inlet 19A of the catalyst 19, and stands from the other end opening 18 in a direction opposite to the inlet 19A of the catalyst 19 (upward in FIG. 2). The outer peripheral wall 16A is provided, and a tip wall 16B that covers the tip of the outer peripheral wall 16A is formed. Further, the collective portion 16 is provided with a protruding portion 21.
The protrusion 21 is formed such that the top 21A is raised on the tip wall 16B on the other end opening 18 side (that is, in the direction of the catalyst inlet 19A; the downward direction in FIG. 2), and the shape thereof is the top 21A. Is a right cone shape located on the catalyst 19 side. Further, the top 21A and the bottom 21D of the projection 21 are formed to be perfect circles in a top view as shown in FIG.

Further, the protrusion 21 is formed so as to encompass the branch pipe axis @ 13 C, 14C, the axis perpendicular to the cross-section of each branch 13, 14, 15 are projected along the 15C (see in Fig. 2 numeral X ₁₎ Has been.
Further, the angle θ ₂ formed between the peripheral surface 21B of the projection 21 and each branch pipe axis 13C, 14C, 15C is arranged to be about 125 degrees in the sectional view shown in FIG.

  Further, the peripheral surface 21B is a perfect circle in a top view as shown in FIG. 1, and thereby makes contact with any axis 13C, 14C, 15C of each branch pipe 13, 14, 15 at the same angle. It is formed as follows. In other words, when the exhaust manifold 10 is viewed from above as shown in FIG. 1, the normal line at the intersection of the peripheral surface 21B of the protrusion 21 and the branch pipe axes 13C, 14C, 15C and the branch pipe axes 13C, 14C. , 15C are formed so as to coincide with each other.

Further, the protrusion 21 has its vertical axis 21C, that is, the center 21C of the protrusion 21 when the exhaust manifold 10 is viewed from above as shown in FIG. , 14C and 15C are arranged at the intersections.
The collecting portion 16 is formed so as to have a sufficient volume with respect to the flow rate of the exhaust gas flowing through the first to third branch pipes 13, 14, and 15. It is possible to avoid a substantial resistance.

Since the exhaust pipe structure of the engine according to one embodiment of the present invention is configured as described above, the following operations and effects are achieved.
Here, the flow velocity distribution of the exhaust gas in the collecting section 16 in the EE cross section of FIGS. 2 and 3 is shown in FIG. 6, and the flow velocity distribution of the exhaust gas in the catalyst 19 in the FF cross section of FIGS. Is shown in FIG. These flow velocity distribution diagrams shown in FIGS. 6 and 7 show a case where exhaust gas is sent from the first branch pipe 13 to the collecting portion 16 (see FIGS. 4 and 5). Moreover, in these FIG.6 and FIG.7, the part shown with a dark color has shown the part where the flow velocity is fast, and the part shown with a light color has shown the part where the flow rate is slow.

As shown in FIG. 6, the speed of the exhaust gas is not biased and is well distributed. As indicated by the arrows in FIG. 6, the exhaust gas sent from the first branch pipe 13 to the collecting portion 16 collides with the protrusion 21 in the collecting portion 16, and the outer peripheral wall of the collecting portion 16. It is considered that it was due to 16A hitting and sufficient stirring.
In this regard, when comparing FIG. 6 with FIG. 10, which is an exhaust gas distribution diagram in the collective portion 106 of the exhaust manifold 100 where the protrusions 21 are not provided, the difference is obvious.

  That is, as shown in FIG. 10, the flow rate of the exhaust gas sent from the first branch pipe 103 into the aggregation unit 106 is fast near the outer periphery in the aggregation unit 106, becomes substantially zero near the center, and the flow rate is extremely high. It is unevenly distributed. On the other hand, as shown in FIG. 6, in the present invention according to the present embodiment, although the flow velocity is high at a part of the protrusion 21, the flow velocity is uniformly distributed as a whole. There is no bias.

Further, as shown in FIG. 7, there is no portion in the catalyst 19 where the flow rate is extremely slow. This difference is clear when FIG. 7 is compared with FIG. 11 showing the flow velocity distribution of the exhaust gas flow in the catalyst 109 into which the exhaust gas has flowed through the exhaust manifold 100 where the protrusions 21 are not provided. In particular, the extremely slow flow rate portion generated as indicated by reference numeral P ₁₀₉ in FIG. 11 disappears in the present embodiment shown in FIG. 7, and the exhaust gas is purified by the entire catalyst 19. You can see that

As described above, according to the exhaust pipe structure of the engine according to the embodiment of the present invention, the exhaust gas supplied to the catalyst 19 is agitated, whereby the deviation of the flow rate of the exhaust gas in the catalyst 19 can be suppressed. As a result, the entire catalyst 19 can be used effectively, and the exhaust gas performance can be improved.
Further, the protruding portion 21 is formed so as to include a cross section of each of the first to third branch pipes 13, 14, 15 projected along the respective axis lines 13C, 14C, 15C of the first to third branch pipes. As a result, the exhaust gas discharged to the collecting portion 16 via the branch pipes 13, 14, and 15 can be reliably applied to the protruding portion 21, thereby promoting the stirring of the exhaust gas. .

Further, since the outer peripheral wall 16A is formed in the collecting portion 16, the exhaust gas stirred by the protrusion 21 can be further applied to the outer peripheral wall 16A to promote stirring.
In addition, since the protruding portion 21 is raised in the direction of the inlet of the catalyst 19 and formed in a conical shape at the tip portion 16B in the collecting portion 16, the exhaust gas is made to flow toward the catalyst 19 while stirring the exhaust gas. It can be guided promptly.

In addition, by forming the protrusion 21 in a conical shape, the protrusion 21 can be processed by pressing, and the mold can be easily extracted even when the protrusion 21 is processed by casting. Therefore, workability can be improved.
Moreover, each branch pipe axis @ 13 C, 14C, so that the angle theta ₁ formed between 15C and the catalyst axis 19C is an obtuse angle, with each branch pipe 13, 14, 15 and catalyst 19 are arranged, the protrusion 21 circumferential surface 21B and the branch pipe axes @ 13 C, 14C, the angle theta ₂ formed between 15C is so as to form an obtuse angle, the branch pipe 13, 14, 15 and the circumferential surface 21B is disposed. As a result, the exhaust gas that has hit the peripheral surface 21B of the protrusion 21 can be quickly introduced into the catalyst 19 while the flow direction is deflected at a gentle angle and stirred.

Further, since the exhaust gas flowing through the branch pipes 13, 14, and 15 can be applied to the protrusions 21 under the same conditions, the variation in the degree of stirring of the exhaust gas can be prevented, and the exhaust gas flow velocity in the catalyst 19 can be prevented. Can be avoided.
Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various modifications can be made without departing from the spirit of the present invention.

  In the above-described embodiment, the case where the protrusion 21 is a right cone and the bottom surface shape is a perfect circle has been described as an example, but the present invention is not limited to such a shape. For example, a pyramid shape, a cylindrical shape, a prism shape, or the like may be used.

1 is a schematic top view showing an exhaust manifold of an engine exhaust pipe structure according to an embodiment of the present invention. It is DD sectional drawing of FIG. 1 which shows the exhaust manifold of the exhaust pipe structure of the engine which concerns on one Embodiment of this invention. 1 is a schematic external view showing an exhaust manifold of an engine exhaust pipe structure according to an embodiment of the present invention. It is a typical top view showing the exhaust gas flow which flows through the inside of the exhaust manifold of the exhaust pipe structure of the engine concerning one embodiment of the present invention. It is DD sectional drawing of FIG. 1 which shows the exhaust gas flow which flows through the inside of the exhaust manifold of the exhaust pipe structure of the engine which concerns on one Embodiment of this invention. It is a schematic diagram which shows exhaust gas velocity distribution in the exhaust manifold of the exhaust pipe structure of the engine which concerns on one Embodiment of this invention. It is a schematic diagram which shows the exhaust gas velocity distribution in the catalyst of the exhaust pipe structure of the engine which concerns on one Embodiment of this invention. It is a typical top view which shows the exhaust manifold in the technique created in the process of creating this invention. It is AA sectional drawing of FIG. 8 which shows the exhaust manifold in the technique created in the process of inventing this invention. It is a schematic diagram which shows the exhaust gas velocity distribution in the exhaust manifold in the technique created in the process of creating the present invention. It is a schematic diagram which shows the exhaust gas velocity distribution in the catalyst in the technique created in the process of creating this invention.

Explanation of symbols

11 Engine 13 First branch pipe (Exhaust gas passage)
14 Second branch pipe (exhaust gas passage)
15 3rd branch pipe (exhaust gas passage)
16 Assembly part 16A Outer peripheral wall 16B End wall 17 One end opening 18 Other end opening 19 Catalyst 21 Projection part 21A Top part

Claims (7)

An exhaust gas passage through which exhaust gas discharged from the engine flows, a catalyst for purifying the exhaust gas, a collecting portion whose one end opening is connected to the outlet of the exhaust gas passage and the other end opening is connected to the inlet of the catalyst; The exhaust pipe structure of the engine with
The exhaust gas passage and the catalyst are disposed such that the axis of the exhaust gas passage and the axis of the catalyst intersect.
The exhaust pipe structure of an engine, wherein the collecting portion includes a protrusion formed at a location where the axis of the exhaust gas passage intersects with the axis of the catalyst. 2. The engine exhaust pipe structure according to claim 1, wherein the protrusion is formed so as to include a cross section orthogonal to the axis of the exhaust gas channel projected along the axis of the exhaust gas channel. The assembly includes an outer peripheral wall forming the other end opening connected to the catalyst inlet;
A tip wall covering the tip of the outer peripheral wall,
The engine exhaust pipe structure according to claim 1 or 2, wherein the protrusion is formed so as to protrude toward the opening of the other end of the tip wall. The protrusion is formed in a conical shape whose top is raised to the opening side of the other end.
The exhaust pipe structure for an engine according to any one of claims 1 to 3, wherein The exhaust gas passage and the catalyst are disposed so that the axis of the exhaust gas passage and the axis of the catalyst form an obtuse angle,
The engine exhaust pipe structure according to claim 4, wherein a peripheral surface of the projecting portion formed in the conical shape is disposed at an obtuse angle with respect to an axis of the exhaust gas passage. A plurality of the exhaust gas passages are provided,
6. The engine exhaust pipe structure according to claim 1, wherein a central axis of the protrusion is disposed at an intersection of axes of the plurality of exhaust gas passages. 7. The engine according to claim 6, wherein a peripheral surface of the protrusion on the exhaust passage side is formed so as to intersect at any angle with respect to any axis of the plurality of exhaust gas passages. Exhaust pipe structure.

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