JP2009121439A - Exhaust system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust system of an internal combustion engine capable of immediately starting exhaust gas purification of a bypass catalyst converter just after starting the internal combustion engine whose a main catalyst converter is not activated. <P>SOLUTION: The exhaust system of an internal combustion engine includes a plurality of upstream-side main bypass passages 2 respectively branched from a branching point arranged at an upstream-side of four upstream-side main passages, and an opening and closing switching valve 6 for opening and closing the upstream-side main passages 2 at a downstream-side rather than the branching point. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust system for an internal combustion engine that performs exhaust purification using a catalytic converter, and in particular, opens and closes to guide the exhaust to the bypass channel side provided with another catalytic converter immediately after a cold start when the main catalytic converter is not activated. The present invention relates to an exhaust device for an internal combustion engine including a switching valve.

Conventionally, as an exhaust device of this type of internal combustion engine, an upstream main passage for each cylinder connected to each cylinder, a downstream main passage formed by joining the upstream main passages of a plurality of cylinders, and this downstream Side main passage or a main catalytic converter interposed in a downstream flow passage, a bypass passage branched from the upstream main passage and including a bypass catalytic converter, and exhaust discharged from each cylinder A flow path opening / closing switching valve that opens and closes the upstream main passage so as to flow to the bypass passage, and shuts off communication between the upstream main passages when the upstream main passage is closed. A housing in which valve openings for each cylinder corresponding to the side main passage are formed in two rows, and arranged on both sides of the housing so as to sandwich the plurality of valve openings. There is known a structure including a pair of rotating shafts and a plurality of valve bodies attached to the rotating shafts and swinging integrally with the rotating shafts to open and close the valve openings. (For example, see Patent Document 1).
JP 2007-46556 A

  However, in the exhaust system of the internal combustion engine of the conventional example, the bypass catalytic converter is arranged at a position upstream of the main catalytic converter, but since the distance from the exhaust port of each cylinder is large, immediately after the start of the internal combustion engine Therefore, there is a problem that exhaust gas purification by the bypass catalytic converter cannot be started immediately.

  The problem to be solved by the present invention is to provide an exhaust system for an internal combustion engine that can immediately start exhaust purification by a bypass catalytic converter immediately after the start of the internal combustion engine.

  In order to solve the above-mentioned problem, an exhaust system for an internal combustion engine according to claim 1 includes a plurality of upstream main passages connected to a plurality of exhaust ports of the internal combustion engine, and a downstream side of the plurality of upstream main passages. Branching from a branching point provided on the upstream side of each of the plurality of upstream main passages, a merging portion for collecting the two in the downstream main passage, a main catalytic converter interposed in the downstream main passage, A plurality of the upstream bypass passages, a bypass catalytic converter connected in a state where the downstream sides of the plurality of upstream bypass passages are combined into a single bypass passage, and a downstream side of the bypass catalytic converter A downstream bypass passage connected between the junction and the main catalytic converter, and an open / close switching valve for opening and closing the upstream main passage downstream from the branch point. It was a means, characterized in that.

  In the exhaust system for an internal combustion engine of the present invention, as described above, a plurality of upstream bypass passages branched from the branch points provided on the upstream side of the plurality of upstream main passages, and the branch points By adopting a configuration including an open / close switching valve that opens and closes the upstream main passage on the downstream side, the distance from the exhaust port of each cylinder to the bypass catalytic converter can be reduced.

  Therefore, it is possible to obtain an effect that exhaust gas purification by the bypass catalytic converter can be started immediately after starting the internal combustion engine in which the main catalytic converter is not activated.

  Embodiments of the present invention will be described below with reference to the drawings.

  The exhaust system for an internal combustion engine according to the first embodiment corresponds to the invention described in claims 1, 2, 4, and 5.

  First, an exhaust system for an internal combustion engine according to the first embodiment will be described with reference to the drawings.

  1 is an overall configuration diagram showing an exhaust system for an internal combustion engine according to the first embodiment, FIG. 2 is a perspective view showing the exhaust system for the internal combustion engine according to the first embodiment, and FIG. 3 is an open / closed view from the direction of arrow A1 in FIG. FIG. 4 is a perspective view showing a single on-off switching valve in the exhaust device for an internal combustion engine according to the first embodiment, and FIG. 5 is an enlarged longitudinal sectional view taken along line BB in FIG.

  The exhaust system of the internal combustion engine includes a cylinder head 1 of the internal combustion engine, four upstream main passages 2, one downstream main passage 3, a merging portion 4, a main catalytic converter 5, and an open / close switching valve 6. Four upstream bypass passages 7, one bypass passage 8, a bypass catalytic converter 9, and a downstream bypass passage 10 are provided.

  More specifically, as shown in FIGS. 1 and 2, the four exhaust ports # 1 to # 4 arranged in series with the cylinder head 1 of the internal combustion engine are fixed to the cylinder head 1 with fixing bolts 12. The upstream main passages 2 are connected to the head flanges 11 respectively.

  At the downstream side of the four upstream main passages 2, a merging portion 4 that connects the downstream sides to one downstream main passage 3 is connected. The main catalytic converter 5 is interposed in the downstream main passage 3 that is downstream of the junction 4.

  The main catalytic converter 5 has a large capacity disposed under the floor of the vehicle, and includes a three-way catalyst and an HC trap catalyst as the catalyst.

  The four open / close switching valves 6 open and close the respective upstream main passages 2 at the same time, and serve to switch the flow of exhaust gas to the respective upstream bypass passages 7 when the valves are closed. It is installed on the upstream side.

  The four on-off switching valves 6 are interposed in a state where they are arranged side by side so that the switching operation can be performed on one axis.

  As shown in FIG. 5, each open / close switching valve 6 includes a valve opening 61 having a tapered seating surface 61 a whose inner surface communicating with the upstream main passage 2 is a part of a spherical surface on the downstream side of the housing 60. A valve body 62 for opening and closing the valve opening 61 is provided.

The valve body 62 includes a valve portion 62b having a curved seat portion 62a whose outer surface is a part of a spherical surface, and a bolt (valve shaft) 62c screwed to the shaft center portion of the valve portion 62b. .
The bolt 62c is swingably connected to a mounting hole 63a having a diameter slightly larger than the diameter of the bolt 62c formed at the tip of the rotating arm 63, and the rotating arm 63 is connected to the rotating operation shaft 64. The valve opening 61 is opened and closed by the valve 62b by rotating with the rotation of the rotation operation shaft 64.

  That is, the bolt 62c of the valve body 62 is swingably connected to the rotating arm 63 so that the centering function of the valve body 61 with respect to the valve opening 61 is exhibited when the valve body 62 is closed. It has become.

  The rotation operation shaft 64 is an actuator (not shown) arranged over the four open / close switching valves 4 so that the four open / close switching valves 6 can be switched in one axis. By being rotationally driven, the four open / close switching valves 6 can be switched simultaneously by only one actuator.

On the other hand, when the valve element 62 is opened, the tip end surface of the head 62d of the bolt 62c comes into contact with the inner surface of the housing 60, thereby preventing the valve element 62 from swinging with respect to the rotating arm 63. .
That is, in the first embodiment, the tapered portion 62e is formed on the outer peripheral edge of the tip 62d of the head 62d of the bolt 62c, and the tapered inner peripheral wall 6a with which the tapered portion 62e abuts is provided on the inner surface side of the housing 60. A recess 6b is formed.

  A communication hole 65 that communicates with the upstream bypass passage 7 is formed in the housing 60 of each open / close switching valve 6.

  The upstream bypass passage 7 connected to each communication hole 65 has a sufficiently smaller passage cross-sectional area than the upstream main passage 2, and is adjacent to each other among the four upstream bypass passages 7. The downstream sides of the upstream exhaust passage # 1 and the upstream bypass passage 7 on the # 2 side join each other as one intermediate bypass passage 8a at the junction P1. Similarly, the exhaust port # 3 and the upstream bypass passage 7 on the # 4 side that are adjacent to each other join each other as one intermediate bypass passage 8b at the junction P2.

  Further, the downstream sides of the intermediate bypass passages 8a and 8b merge together as one intermediate bypass passage 8c at the junction P3, and the bypass catalytic converter 9 is connected to the downstream side of the intermediate bypass passage 8c.

  The downstream side of the bypass catalytic converter 9 is connected to the downstream main passage 3 between the junction 4 and the main catalytic converter 5 via the downstream bypass passage 10.

  The bypass catalytic converter 9 includes therein a first catalyst 9a and a second catalyst 9b which are two monolith catalyst carriers divided in the front and rear directions.

  One end of the exhaust gas recirculation passage 9d is connected to a gap 9c between the first catalyst 9a and the second catalyst 9b. The other end of the exhaust gas recirculation passage 9d extends to the engine intake system via an exhaust gas recirculation control valve (not shown).

  Further, the bypass catalytic converter 9 is a small one having a smaller capacity than the main catalytic converter 5, and preferably a catalyst excellent in low temperature activity is used.

Further, the bypass catalytic converter 9 is disposed as upstream as possible in the bypass passage.
That is, the upstream bypass passage 7 and the intermediate bypass passages 8a, 8b, and 8c are also formed as short as possible.

  Therefore, the exhaust gas flowing into the upstream bypass passage 7 is immediately purified by the bypass catalytic converter 9, then returns to the downstream main passage 3, flows through the main catalytic converter 5, and flows down while warming the main catalytic converter 5. .

  Next, the operation of the first embodiment will be described.

First, switching of the opening / closing switching valve 6 will be described.
In the exhaust system for an internal combustion engine configured as described above, the switching valve 6 is closed when the temperature of the main catalytic converter 5 or the temperature of the internal combustion engine or the exhaust gas temperature after the cold start of the internal combustion engine is low. In addition, illustration of a temperature detection sensor is abbreviate | omitted.
Therefore, the entire amount of exhaust discharged from the exhaust ports # 1 to # 4 flows to the bypass catalytic converter 9 via the upstream bypass passage 7 and the intermediate bypass passages 8a and 8b.

  The bypass catalytic converter 9 is located on the upstream side of the exhaust system, that is, near the exhaust ports # 1 to # 4, and is small in size, so that it is activated quickly and exhaust purification is started at an early stage.

The purified exhaust gas flows down while raising the temperature of the main catalytic converter 5. At this time, the four open / close switching valves 6 are closed, so that the upstream main passages 2 of the exhaust ports # 1 to # 4 are not in communication with each other on the upstream side.
Therefore, the phenomenon that the exhaust discharged from one exhaust port # 1 to # 4 flows into the upstream main passage 2 of the other exhaust ports # 1 to # 4 is prevented, and the exhaust temperature drop due to this wraparound is ensured. Avoided.

On the other hand, when the warm-up of the internal combustion engine progresses and the temperature of the main catalytic converter 5 is increased and activated by the exhaust gas flowing through the bypass catalytic converter 9, it is not shown based on the measured value of the temperature of the main catalytic converter 5. The actuator operates through the control circuit, and the four open / close switching valves 6 open simultaneously.
Alternatively, the open / close switching valve 6 may be opened when a measured value such as the cooling water temperature or the exhaust gas temperature of the internal combustion engine becomes sufficiently high.

  By opening the on / off switching valve 6, the exhaust discharged from the exhaust ports # 1 to # 4 mainly passes through the upstream main passage 2 and is gathered in the downstream main passage 3 at the junction 4. Passes through the main catalytic converter 5.

At this time, the bypass flow path side is not particularly shut off, but the bypass flow path side has a smaller passage cross-sectional area than the main flow path side, and the bypass catalytic converter 9 is interposed. Most of the exhaust flow passes through the main flow path side and hardly flows into the bypass flow path side.
Therefore, the thermal deterioration of the bypass catalytic converter 9 is sufficiently suppressed.

Next, the operation of the open / close switching valve 6 according to the first embodiment will be described.
When the open / close switching valve 6 is closed, the turning arm 63 is rotated through the turning operation shaft 64 to a predetermined angle, so that the curved seat 62a of the valve body 62 becomes a tapered seat 61a. The valve opening 61 is seated and closed.

Here, even when the center of the valve body 62 is slightly deviated from the center of the valve opening 61 when the valve body 62 closes the valve opening 61, The curved seat portion 62a slides on the tapered seat surface 61a and is aligned, so that the valve body 62 can be seated on the tapered seat surface 61a in a good posture and sealed well. .
Alternatively, the valve body 62 can be reliably seated and sealed on the tapered seat surface 61a even when the valve body 62 is slightly swung.

  Furthermore, the pressure difference between the upstream side and the downstream side of the valve opening 61 causes the valve body 62 to be pressed and brought into close contact with the tapered seat surface 61a, thereby improving the sealing performance.

  On the other hand, when the opening / closing switching valve 6 is opened, the rotation arm 63 is rotated through the rotation operation shaft 64 to reach a predetermined angle, thereby opening the valve opening 61. Then, the rotating arm 63 moves the head 62d so that the tapered portion 62e formed at the tip edge of the head 62d of the bolt 62c contacts the tapered inner peripheral wall 6a of the recess 6b formed on the inner surface of the housing 60. By pressing against the inner surface side of the housing 60, the swinging of the valve body 62 with respect to the rotating arm 63 can be restricted.

  Next, the effect of the first embodiment will be described.

  In the exhaust system for the internal combustion engine of the first embodiment, as described above, a plurality of upstream bypass passages 2 branched from the branch points provided on the upstream side of the four upstream main passages, and the branches By providing the structure with the open / close switching valve 6 that opens and closes the upstream main passage 2 downstream from the point, the distance from the exhaust ports # 1 to # 4 of each cylinder to the bypass catalytic converter 9 can be reduced. it can.

  Therefore, it is possible to obtain an effect that the exhaust purification by the bypass catalytic converter 9 can be started immediately after the start of the internal combustion engine in which the main catalytic converter 5 is not activated.

  In addition, since the communication holes 65 communicating with the upstream bypass passage 7 are formed in the housings 60 of the four on-off switching valves 6, the upstream bypass passages 7 are provided in the middle of the upstream main passages 2. The connection work can be simplified as compared with the case where each is connected.

  Further, since the four open / close switching valves 6 are arranged side by side in a row, the switching operation of the four open / close switching valves 6 can be performed by only one rotation operation shaft 64. Thereby, the number of parts can be reduced and simplified, and the degree of freedom of the arrangement position is improved. Also, four or more open / close switching valves can be handled by one axis (one rotation operation axis 64).

  Further, since each housing 60 of the on-off switching valve 6 is provided separately and separately, it can be easily handled according to the number of cylinders compared to the case where it is formed integrally, and the degree of freedom in design is increased.

  Further, the bolt 62c constituting the valve shaft of the valve body 62 is slidably connected to the rotating arm 63 so that the valve body 62 is aligned with the valve opening 61 when the valve body 62 is closed. It can be demonstrated. Thereby, the favorable sealing performance of the valve opening 61 can be ensured.

  Further, a tapered portion 62e is formed on the outer peripheral edge of the tip of the head 62d of the bolt 62c, while a concave portion 6b having a tapered inner peripheral wall 6a with which the tapered portion 62e abuts is formed on the inner surface side of the housing 60. With this configuration, it is possible to prevent the valve element 62 from swinging when the valve is opened. As a result, it is possible to prevent vibration noise and adverse effects on the exhaust system due to vibration.

  Next, another embodiment will be described. In the description of the other embodiments, the same components as those of the first embodiment are not shown, or the same reference numerals are given and the description thereof is omitted, and only the differences are described.

The exhaust system for an internal combustion engine according to the second embodiment corresponds to the invention described in claim 3.
In the second embodiment, as shown in FIG. 6, the flange 6 c provided on the upstream side of the four open / close switching valves 6 is connected and fixed to the cylinder head 1 of the internal combustion engine together with the head flange 11 by the fixing bolt 12. This is different from the first embodiment.

  That is, each open / close switching valve 6 is directly connected to the head flange 11 that requires high manufacturing accuracy, and the head flange 11 is fastened to the cylinder head 1 together.

  Therefore, in the second embodiment, the same effect as in the first embodiment can be obtained, and one shaft can be arranged with high accuracy by assembling a plurality of on-off switching valves 6 in a horizontal row state. The opening / closing operation by (one rotation operation shaft 64) can be performed satisfactorily.

  As shown in FIG. 7, the exhaust device for the internal combustion engine of the third embodiment is different from the first and second embodiments in that the rotation operation shaft 64 is on the communication hole 65 side to which the upstream bypass passage 7 is connected. Is different.

  Therefore, in the third embodiment, the same effects as in the first embodiment can be obtained, and the valve portion 62b is positioned so as to close the communication hole 65 when the on-off switching valve 6 is opened. The gas flow can be reduced.

  Furthermore, in the third embodiment, the tapered opening edge 6d formed at the opening edge of the communication hole 65 is in contact with the tapered portion 62e formed at the outer peripheral edge of the tip 62d of the head 62d of the bolt 62c. By making the communication hole 65 closed, it is possible to stop the flow of the exhaust gas to the bypass flow path side and to prevent the valve body 62 from swinging when the valve is opened. The adverse effect on the exhaust system due to vibration can be prevented.

  In the third embodiment, since the valve opening 61 of the on / off switching valve 6 is inclined downward, when the valve element 62 rotates upward when the on / off switching valve 6 is opened, the on / off switching valve 6 Since the high-temperature exhaust gas flowing into the valve heads directly to the valve body 62, there is a problem with the durability of the valve body 62. In the third embodiment, the valve body rotates downward when the on-off switching valve 6 is opened. By moving, the amount of high-temperature exhaust gas that strikes the body 62 can be reduced, thereby improving the durability of the valve body 6.

  Although the present embodiment has been described above, the present invention is not limited to the above-described embodiment, and design changes and the like within a scope not departing from the gist of the present invention are included in the present invention.

  For example, in the embodiment, an example in which the present invention is applied to an internal combustion engine having four exhaust ports # 1 to # 4 is shown, but the number of exhaust ports is arbitrary.

  Moreover, although the example in which each housing 60 of the opening / closing switching valve 6 is provided separately and separately has been described in the embodiment, the housings of the plurality of opening / closing switching units 6 may be integrally formed.

1 is an overall configuration diagram illustrating an exhaust device for an internal combustion engine according to a first embodiment. 1 is a perspective view illustrating an exhaust device for an internal combustion engine according to a first embodiment. It is a figure which shows the on-off switching valve unit seen from the A1 arrow direction of FIG. FIG. 3 is a perspective view showing a single open / close switching valve in the exhaust device of the internal combustion engine according to the first embodiment. FIG. 5 is an enlarged longitudinal sectional view taken along line BB in FIG. 4. FIG. 6 is an explanatory cross-sectional view showing an attachment state of an open / close switching valve in an exhaust device for an internal combustion engine according to a second embodiment. FIG. 6 is an explanatory cross-sectional view showing an open / close switching valve in an exhaust device for an internal combustion engine according to a third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder head # 1-# 4 of an internal combustion engine 11 Head flange 12 Fixing bolt 2 Upstream main passage 3 Downstream main passage 4 Junction part 5 Main catalytic converter 6 Open / close switching valve 6a Tapered inner peripheral wall 6b Concave part 6c Flange 6d Tapered opening edge 60 Housing 61 Valve opening 61a Tapered seat surface 62 Valve body 62a Curved seat portion 62b Valve portion 62c Bolt (valve shaft)
62d Head 62e Tapered portion 63 Rotating arm 63a Mounting hole 64 Rotating operation shaft 65 Communication hole 7 Upstream bypass passage 8a Intermediate bypass passage 8b Intermediate bypass passage 8c Intermediate bypass passage 9 Bypass catalytic converter 9a First catalyst 9b Second catalyst 9c Gap 9d Exhaust recirculation passage 10 Downstream bypass passage P1 Merge point P2 Merge point P3 Merge point

Claims (5)

A plurality of upstream main passages respectively connected to a plurality of exhaust ports of the internal combustion engine;
A merging portion for gathering the downstream side of the plurality of upstream main passages into one downstream main passage;
A main catalytic converter interposed in the downstream main passage;
A plurality of each upstream bypass passage branched from a branch point provided on the upstream side of each of the plurality of upstream main passages;
A bypass catalytic converter connected in a state where the downstream side of the plurality of upstream bypass passages is assembled into one bypass passage;
A downstream bypass passage connected downstream of the bypass catalytic converter between the junction and the main catalytic converter;
An on-off switching valve that opens and closes the upstream main passage downstream from the branch point;
An exhaust system for an internal combustion engine, comprising:   The exhaust system for an internal combustion engine according to claim 1, wherein a communication hole communicating with the upstream bypass passage is formed in a housing of the plurality of on-off switching valves.   3. The exhaust system for an internal combustion engine according to claim 1, wherein upstream sides of the plurality of on-off switching valves are connected to a head flange. 4.   The exhaust system for an internal combustion engine according to any one of claims 1 to 3, wherein the plurality of on / off switching valves are arranged side by side so that the switching of the plurality of on / off switching valves can be performed in one axis. An exhaust system for an internal combustion engine characterized by the above. 5. The exhaust system for an internal combustion engine according to claim 1, wherein the plurality of on-off switching valves include a valve opening portion having a tapered seat surface communicating with each of the upstream main passages, and a curved surface. The valve body of the valve body having a cylindrical seat portion is provided with a pivoting arm that is swingably coupled, and the valve portion of the valve body and the seat surface of the valve opening are separated and closely contacted by the displacement of the pivoting arm. It has an alignment function that opens and closes,
An exhaust system for an internal combustion engine, wherein the valve body is configured to be prevented from swinging when the valve shaft is in contact with an inner surface of a housing of the valve body when the valve body is opened.

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