JP4546265B2 - Exhaust system for multi-cylinder engine - Google Patents

Description

  The present invention relates to an exhaust device that constitutes at least a part of an exhaust system (exhaust system) of a multi-cylinder engine.

  In a vehicular multi-cylinder engine, exhaust gas discharged from each cylinder is led to an exhaust pipe on the downstream side through an exhaust manifold. As a configuration form of such an exhaust system, a single exhaust structure in which all branch pipes (branches) constituting the exhaust manifold are gathered into one exhaust pipe or a single pipe structure is common. In a cylinder engine, a dual exhaust structure can also be adopted. In the dual exhaust structure, generally, two branch pipes corresponding to two cylinders selected in consideration of the ignition order are combined into one unit to set one unit exhaust passage, and two units of such exhaust passages are arranged in parallel. The exhaust system below the exhaust manifold is constructed. According to the dual exhaust structure, it is possible to avoid exhaust interference that tends to be a problem in the single exhaust structure and to improve the output. The engine performance tends to improve as the length of the exhaust passage in the two-unit parallel state (generally referred to as “dual length”) is secured longer.

  As an example of the dual exhaust structure, an exhaust device of an in-line four-cylinder engine disclosed in Patent Document 1 can be given. In the exhaust system, both the exhaust manifold and the front tube connected thereto are dualized. In particular, for the exhaust manifold, a double structure comprising an outer cylinder and an inner cylinder is adopted, and the inner cylinder disposed in the outer cylinder is bifurcated. The exhaust gases from the No. 2 and No. 3 exhaust ports are combined into one by a bifurcated inner cylinder, and the exhaust gases from the No. 1 and No. 4 exhaust ports are combined into an outer cylinder (more precisely, the It is put together by the gap space). According to this exhaust device, it is possible to easily realize the equal length of the four branch pipes without complicating the three-dimensional shape of each branch pipe, and there is a merit for back pressure countermeasures.

  By the way, in recent vehicle engines, an A / F sensor (air-fuel ratio sensor), which is a kind of oxygen concentration sensor, is installed in an exhaust system for the purpose of cleaning exhaust gas from the engine as much as possible. There is a tendency to use the oxygen concentration value in the exhaust gas measured in step 1 for feedback control of an engine or the like. As a matter of course, the A / F sensor needs to be positioned upstream of the exhaust gas purifying catalytic converter and the stress relaxation mechanism (such as a ball joint) just before the exhaust gas purifying catalytic converter. For this reason, even in an exhaust system that adopts the dual exhaust structure as described above, it is necessary to monitor the oxygen concentration of exhaust gas exhausted from all cylinders with a single A / F sensor. A single pipe portion (single exhaust passage portion) was set at an intermediate position between the two and the dual exhaust passage portion, and an A / F sensor was attached to the single pipe portion.

  However, as described above, if the sensor mounting single pipe portion must be set immediately after the dual exhaust passage portion, the dual length must be shortened by at least the length of the sensor mounting single pipe portion, There is a possibility that the merit of adopting the dual exhaust structure may be impaired. Patent Document 1 does not disclose a gas sensor such as an oxygen concentration sensor, and does not disclose or suggest the relationship between the dual exhaust structure and the gas sensor.

JP 2001-65340 A

  An object of the present invention is to provide an exhaust device for a multi-cylinder engine in which a gas sensor can be installed in an exhaust system without impairing the merit of the dual exhaust structure.

The invention of claim 1 is an exhaust system comprising a dual-structure exhaust collecting portion for collecting a plurality of branch pipes corresponding to the exhaust ports of each cylinder of a multi-cylinder engine,
The dual structure exhaust collecting portion includes an inner pipe member having two or more inlet portions and a single outlet portion, and constructing an inner exhaust passage for collecting two or more branch pipes into one, and the inner pipe member And an outer pipe member that constructs an outer exhaust passage that collects other branch pipes together in the outer peripheral area of the inner pipe member,
The outlet portion of the inner tube member is formed in a single tube, the outlet portion of the outer tube member surrounding the single tube outlet portion is also formed in a single tube, and the single tube outlet portion of the inner tube member is an outer tube. It is arranged eccentrically with respect to the single tubular outlet of the tube member,
Wherein the exhaust collector of a dual structure, gas sensor, so as to penetrate the outer pipe member and the inner pipe member, and, the cross-sectional area by the eccentric arrangement of the outer gas exhaust path at the outlet portion of the exhaust collector An exhaust system for a multi-cylinder engine is provided so as to occupy a relatively large portion .

According to the first aspect of the present invention, the gas sensor is provided so as to penetrate the outer tube member and the inner tube member with respect to the exhaust structure having a dual structure including the inner tube member and the outer tube member. Therefore, the single gas sensor can simultaneously detect the exhaust gas flowing in both the inner exhaust passage constructed by the inner tube member and the outer exhaust passage in the outer peripheral region of the inner tube member constructed by the outer tube member. Further, since the gas sensor is installed in the exhaust structure having a dual structure, the installation of the gas sensor cannot be a cause for shortening the dual length. Therefore, a gas sensor can be installed in the exhaust system of a multi-cylinder engine without impairing the merit of the dual exhaust structure.
In addition, the outlet part of the inner pipe member and the outlet part of the outer pipe member are both formed into a single tube, so that the outlet part of the exhaust collecting part has a double pipe structure, and the outer exhaust passage is cross-sectionally crossed by the inner exhaust passage. It becomes a shape surrounding the ring. Furthermore, since the single tubular outlet portion of the inner tube member is eccentrically arranged with respect to the single tubular outlet portion of the outer tube member, the outer cross-sectional area of the outer pipe of the double tube structure outlet portion is relatively A big part and a small part are born. In this configuration, since the gas sensor is provided so as to occupy a portion where the cross-sectional area of the outer exhaust passage is relatively large due to the eccentric arrangement, the contact area of the gas sensor with respect to the exhaust gas flowing through the outer exhaust passage is sufficiently large. The detection of exhaust gas flowing through the outer exhaust passage is not neglected. Therefore, exhaust gas flowing through both the inner exhaust passage and the outer exhaust passage can be detected by a single gas sensor.

According to a second aspect of the present invention, in the exhaust system for a multi-cylinder engine according to the first aspect, an opening for inserting the gas sensor is formed in a single tubular outlet of the inner tube member. To do.

According to the second aspect , by providing the gas sensor insertion opening at the single tubular outlet of the inner pipe member, the single gas sensor can detect the exhaust gas flowing through both the inner exhaust passage and the outer exhaust passage.

According to a third aspect of the present invention, in the exhaust system for a multi-cylinder engine according to the first aspect , the single tubular outlet portion of the inner tube member has an opening through which the gas sensor is inserted and an upstream side of the opening. The gas communication hole which is located is formed.

According to the third aspect , in addition to the gas sensor insertion opening, the single tubular outlet portion of the inner tube member is provided with a gas communication hole located on the upstream side thereof. This gas communication hole mixes the exhaust gas flowing in the outer exhaust passage (outside of the inner pipe member) and the exhaust gas flowing in the inner exhaust passage (inner side of the inner pipe member) at the upstream position of the gas sensor so as to moderate the gas flow. Provided to disturb. Due to the presence of the gas communication hole, the exhaust gas flowing through both the outer exhaust passage and the inner exhaust passage uniformly strikes the gas sensor that penetrates the inner tube member and the outer tube member. Therefore, the single gas sensor can further improve the performance of uniformly detecting the exhaust gas flowing through both the inner exhaust passage and the outer exhaust passage. Note that the gas sensor insertion opening and the gas communication hole may exist separately, but they may be integrated and exist as one opening.

Additional remarks: Further preferred embodiments and additional components of the present invention are listed below.
4. The gas sensor according to claim 1 , wherein the gas sensor is an oxygen concentration sensor that detects an oxygen concentration in exhaust gas.

  According to the exhaust system for a multi-cylinder engine described in each claim, it is possible to install a gas sensor in the exhaust system without impairing the merit of the dual exhaust structure.

  Several embodiments of the present invention embodied in an exhaust manifold for an in-line four-cylinder engine will be described below with reference to the drawings. Note that cylinder numbers # 1, # 2, # 3, and # 4 are sequentially assigned to the cylinders of the four-cylinder engine to which the exhaust manifold is attached. The engine includes exhaust ports P1 to P4 corresponding to the four cylinders (see FIG. 1).

(First embodiment)
As shown in FIGS. 1 and 2, an exhaust manifold as an exhaust device constituting the most upstream part of the exhaust system includes four branch pipes 1, 2, 3, and 4, and the four branch pipes 1 to 1. 4 includes at least an exhaust collecting portion 5 for bundling four members.

  The four branch pipes 1 to 4 are provided corresponding to the # 1 to # 4 cylinders. Each of the branch pipes 1 to 4 is configured as a branch pipe having a double pipe structure in which the inner pipe is stacked inside the outer pipe. In the branch pipe of this double pipe structure, it is preferable to make the thickness of the inner pipe thinner than the thickness of the outer pipe, thereby preventing the temperature reduction of the exhaust gas due to heat transfer to the inner pipe as much as possible. be able to. The inlet ends of these branch pipes 1 to 4 are connected to the corresponding exhaust ports P1 to P4 via the head flange 6 respectively. The outlet ends of the branch pipes 1 to 4 are connected to the exhaust collecting portion 5.

  As shown in FIGS. 1 to 3, an out flange 7 is mounted near the outlet of the exhaust collecting portion 5. The out flange 7 is a portion for connecting the outlet end of the exhaust collecting portion 5 to a stress relaxation mechanism (not shown), and the outlet end of the exhaust collecting portion 5 is connected to the exhaust gas purifying catalyst via the stress relaxation mechanism. It is connected to a converter (not shown). An A / F sensor 8 as a gas sensor is attached to the exhaust collecting portion 5 so as to pierce from the side. The A / F sensor 8 is a kind of oxygen concentration sensor that detects the oxygen concentration in the exhaust gas. However, the A / F sensor 8 is more than the conventional so-called O-to sensor (narrow sense oxygen concentration sensor) particularly for the purpose of use in lean combustion control. A wide range oxygen concentration sensor designed to detect a wide range of oxygen concentrations.

  As shown in FIGS. 4 to 7, the exhaust collecting portion 5 mainly includes an inner pipe member 10 and an outer pipe member 20 that includes or surrounds the inner pipe member 10.

  As shown in FIG. 6, the inner tube member 10 is a hollow member having two inlet portions 11 and 12 and one outlet portion 13 and having a substantially Y-shaped longitudinal section. The outlet portion 13 of the inner tube member is formed in a single tubular shape, and two inlet portions 11 and 12 branched in a bifurcated shape are provided on the upstream side of the single tubular outlet portion 13. Two branch pipes 1 and 4 corresponding to the # 1 and # 4 two cylinders are connected to the two inlet portions 11 and 12, respectively. Therefore, an inner exhaust passage 14 that collects the two branch pipes 1 and 4 together is constructed in the inner pipe member 10. As shown in FIG. 5, an opening 15 for inserting the distal end portion of the A / F sensor 8 is formed in the wall portion constituting the single tubular outlet portion 13 of the inner tube member.

  As shown in FIG. 6, the outer tube member 20 is provided so as to encompass the entire inner tube member 10. Of the outer tube member 20, the front half (or inlet portion) 21 of the outer tube member that surrounds the two inlet portions 11 and 12 of the inner tube member is formed in a substantially conical surface cover shape (see FIG. 3). The latter half portion (that is, the outlet portion) 23 of the outer tube member surrounding the single tubular outlet portion 13 of the inner tube member is also formed in a single tubular shape. Further, as shown in FIGS. 3 and 6, a closing cover member 26 is fixed to the conical cover-shaped outer tube member front half 21. The closing cover member 26 closes the front opening end in the outer tube member front half 21 and connects the two branch pipes 2 and 3 corresponding to the # 2 and # 3 two cylinders to the outer tube member 20. It also plays a role as a connecting element.

  The outer tube member 20 and the closing cover member 26 ensure a clearance space having a substantially annular cross section in the outer peripheral region of the inner tube member 10, that is, in the region between the inner tube member 10 and the outer tube member 20. . Since the two branch pipes 2 and 3 communicate with this gap space, the outer exhaust passage 24 that collects the two branch pipes 2 and 3 together in the outer peripheral area of the inner pipe member 10 is constructed by the gap space. Is done. In this way, the exhaust collecting portion 5 having a dual exhaust structure is constructed by the inner tube member 10, the outer tube member 20 and the closing cover member 26. As shown in FIG. 7, the four branch pipes 1 to 4 assembled in the exhaust collecting portion 5 are arranged of two branch pipes 1 and 4 corresponding to the # 1 and # 4 two cylinders. The state and the arrangement state of the two branch pipes 2 and 3 corresponding to the # 2 and # 3 two cylinders are relatively arranged so as to be in the diagonal positions of the quadrangle.

  Further, as shown in FIGS. 4 and 5, the single tubular outlet portion 13 of the inner pipe member constituting the inner exhaust passage 14 constitutes the outer exhaust passage 24 at the outlet portion (or the latter half portion) of the exhaust collecting portion 5. The inner tube member outlet portion 13 is connected and supported to the inner peripheral wall of the outer tube member outlet portion 23 by the three support ribs 16 in a state of being eccentrically arranged with respect to the single tubular outlet portion 23 of the outer tube member. More specifically, as shown in FIG. 5, on the downstream side (closer to the outlet) than the position of the A / F sensor 8, the central axis L <b> 1 of the single tubular outlet portion 13 of the inner tube member is a single tubular outlet of the outer tube member. It is eccentric by a predetermined distance from the central axis L2 of the portion 23. Further, on the upstream side of the position of the A / F sensor 8, the cross-sectional area of the single tubular outlet portion 13 of the inner tube member is slightly narrowed. The axis L1 ′ is also more eccentric from the central axis L2 of the single tubular outlet 23 of the outer tube member. As a result, the outer exhaust passage 24 having a substantially annular cross section secured between the single tubular outlet portion 13 of the inner tube member and the single tubular outlet portion 23 of the outer tube member has a relatively large passage sectional area. A part (24a) and a part with a relatively small passage cross-sectional area other than that are born.

  In the exhaust collecting portion 5, the A / F sensor 8 is provided so as to penetrate the outer tube member 20 and the inner tube member 10. At this time, the A / F sensor 8 is positioned so as to occupy a portion (24a) in which the cross-sectional area of the passage is relatively large due to the eccentric arrangement in the outer exhaust passage at the outlet of the exhaust collecting portion 5 ( 4 and 5). The A / F sensor 8 is fixed to a wall portion constituting the single tubular outlet portion 23 of the outer tube member via a ring-shaped sensor boss 9. The front end portion of the A / F sensor 8 is inserted into the opening 15 formed in the single tubular outlet portion 13 of the inner tube member and exposed to the inner exhaust passage 14. Therefore, the oxygen concentration in the exhaust gas flowing through both the inner exhaust passage 14 and the outer exhaust passage 24 can be detected and measured by the single A / F sensor 8.

According to the first embodiment, the following effects can be obtained.
A single A / F sensor 8 can simultaneously detect the exhaust gas flowing through both the inner exhaust passage 14 and the outer exhaust passage 24 in the exhaust collecting portion 5, and the sensor 8 is installed in the dual structure exhaust collecting portion 5. Therefore, the installation of the A / F sensor 8 does not cause the shortening of the dual length, and the dual length can be secured as long as possible.

  Since the A / F sensor 8 is provided in the outer exhaust passage 24 so as to occupy a portion (24a) whose passage cross-sectional area is relatively large due to the eccentric arrangement of the inner pipe member 10, the exhaust gas flowing through the inner exhaust passage 14 Not only that, the contact area of the sensor 8 with the exhaust gas flowing through the outer exhaust passage 24 can be sufficiently secured. Therefore, even if the number of the A / F sensors 8 is one, the single sensor 8 can uniformly detect and measure the oxygen concentration of the exhaust gas flowing through both the inner exhaust passage 14 and the outer exhaust passage 24. As a result, engine control and the like can be performed accurately.

  The exhaust gas flowing through the inner exhaust passage 14 constructed by the inner tube member 10 is kept warm by the exhaust gas flowing through the outer exhaust passage 24 constructed by the outer tube member 20, and reaches the downstream catalytic converter with almost no temperature drop. Therefore, the exhaust gas purification catalyst can be activated early. Further, according to this exhaust device, the exhaust collecting portion 5 has the dual exhaust structure as described above, so that the four branch pipes 1 to 4 can be easily lengthened, and the engine output The improvement etc. can be aimed at.

(Second and third embodiments)
As an embodiment in which the shape and size of the opening (the kind of the opening 15) provided in the wall portion constituting the single tubular outlet portion 13 of the inner tube member 10 is optimized, the second embodiment (FIGS. 8 and 9) is used. ) And the third embodiment (FIGS. 10 and 11) will be described. The configuration of the exhaust collecting portion 5 in the second and third embodiments is basically the same as the configuration of the first embodiment shown in FIGS. 4 to 7, but a single inner pipe member described below is used. The configuration of the opening in the tubular outlet portion 13 is different.

  As shown in FIG. 8 and FIG. 9, in the second embodiment, a single ship-shaped opening 17 is formed through the wall portion constituting the single tubular outlet portion 13 of the inner tube member 10. The ship-shaped opening 17 includes a substantially circular sensor insertion opening 17a for inserting the tip of the A / F sensor 8 and a substantially circular gas positioned upstream of the sensor insertion opening 17a. The communication hole portion 17 b is configured as one continuous opening 17. Since the area of the gas communication hole 17b is smaller than the area of the sensor insertion opening 17a, the opening 17 has a boat shape.

  Further, as shown in FIGS. 10 and 11, in the third embodiment, the distal end portion of the A / F sensor 8 is inserted into the wall portion constituting the single tubular outlet portion 13 of the inner tube member 10. A circular sensor insertion opening 18 and a circular gas communication hole 19 positioned on the upstream side of the sensor insertion opening 18 are separately penetratingly formed. The area of the gas communication hole 19 is set smaller than the area of the sensor insertion opening 18.

  Both the gas communication hole 17b and the gas communication hole 19 in the boat-shaped opening 17 are located upstream of the sensor insertion opening 17a or the sensor insertion opening 18, and the exhaust gas flowing through the outer exhaust passage 24 The exhaust gas flowing through the inner exhaust passage 14 is mixed at an upstream position of the A / F sensor 8 to appropriately disturb the gas flow. That is, due to the presence of the gas communication hole portion 17b or the gas communication hole 19, a part of the exhaust gas flowing through the inner exhaust passage 14 enters the outer exhaust passage 24 through the gas communication hole portions (17b, 19). It becomes possible. As a result, a reverse or reverse flow of the gas flow is generated on the upstream side of the tip shaft portion of the A / F sensor 8 (see FIG. 12), so that the exhaust gas flowing in the outer exhaust passage 24 and the exhaust gas flowing in the inner exhaust passage 14 are generated. Gas mixes and the exhaust gas in a mixed state strikes the tip shaft portion of the A / F sensor 8 sideways.

  As shown in FIG. 12, the tip shaft portion of the A / F sensor 8 has a cylindrical structure in which a sensing portion main body 81 (a portion that generates electromotive force in contact with gas) is covered with a cylindrical cover member 82. . The cylindrical cover member 82 has a plurality of side holes 83 provided in the outer peripheral wall portion thereof, and at least one top hole 84 provided in the tip top wall portion of the cover member 82. In the A / F sensor 8, the exhaust gas that has laterally contacted the tip shaft portion enters the sensor through a part of the side holes 83, contacts the sensing unit main body 81, and then receives the top hole 84 and Retreat out of the sensor through the other side hole 83. Therefore, the gas communication hole 17b or the gas communication hole 19 is added to the single tubular outlet portion 13 of the inner pipe member, and the lateral contact property of the exhaust gas with respect to the tip shaft portion of the A / F sensor 8 is improved. The performance of uniformly detecting the exhaust gas flowing through both the inner exhaust passage 14 and the outer exhaust passage 24 can be enhanced by the single A / F sensor 8.

  In addition, since the gas communication hole 17b or the gas communication hole 19 exists upstream of the sensor insertion opening 17a or the sensor insertion opening 18, a part of the exhaust gas flowing through the outer exhaust passage 24 is partly connected to the inner exhaust passage 14. The exhaust gas flow velocity V crossing the vicinity of the top hole 84 of the tip shaft portion of the A / F sensor 8 is increased, and the negative pressure outside the top hole 84 is increased. As a result, the exhaust gas that strikes the A / F sensor 8 passes through the side hole 83 and is guided to the top hole 84 along the sensing unit main body 81 (that is, around the gas in the sensor). It is possible to pass through the A / F sensor 8 quickly. Therefore, the gas detection sensitivity of the A / F sensor 8 is remarkably improved, and the ability to uniformly detect the exhaust gas flowing through both the inner exhaust passage 14 and the outer exhaust passage 24 by the single A / F sensor 8 is further improved. Can be increased.

  In the second and third embodiments, the area of the gas communication hole 17b or the gas communication hole 19 is set to an appropriate size (or small) (specifically, the sensor insertion opening 17a). (Or, it is set to be smaller than the area of the sensor insertion opening 18), the exhaust gas is not mixed more than necessary, and the merit of the dual exhaust structure is hardly impaired.

(Modification) The embodiment of the present invention may be modified as follows.
In the said 1st-3rd embodiment, although the branch pipes 1-4 were made into the thing of a double pipe structure, the branch pipe of a single pipe structure may be sufficient. In order to reduce the manufacturing cost, for example, the double pipe structure is adopted for the branch pipes 1 and 4 corresponding to the # 1 and # 4 two cylinders, while the other pipes 2 and 3 are single pipes. A structure may be adopted.

  In the first to third embodiments, the branch pipes 1 and 4 corresponding to the # 1 and # 4 two cylinders are connected to the inner pipe member 10, but instead, the # 2 and # 3. The branch pipes 2 and 3 corresponding to the two cylinders may be connected to the inlet portions 11 and 12 of the inner pipe member 10.

The top view which shows the principal part of an exhaust apparatus. The perspective view from the front side of the exhaust apparatus shown in FIG. FIG. 3 is a side view of the exhaust collecting portion viewed from the direction of arrow A in FIG. 2. FIG. 4 is a front view of the exhaust collecting portion viewed from the direction of arrow B in FIG. 3. The schematic sectional drawing in the CC line of FIG. The schematic sectional drawing in the DD line | wire of FIG. The schematic sectional drawing in the EE line of FIG. The schematic sectional drawing equivalent to FIG. 5 in 2nd Embodiment. The schematic sectional drawing in the FF line of FIG. The schematic sectional drawing equivalent to FIG. 5 in 3rd Embodiment. The schematic sectional drawing in the GG line of FIG. The schematic sectional drawing of the front-end | tip axial part vicinity of an A / F sensor.

Explanation of symbols

  1, 2, 3, 4 ... branch pipes, 5 ... exhaust collecting part, 8 ... A / F sensor (gas sensor), 10 ... inner pipe member, 11, 12 ... inlet part of inner pipe member, 13 ... inner pipe member Outlet part, 14 ... inner exhaust passage, 15 ... opening for sensor insertion, 17 ... opening for ship shape, 17a ... opening for sensor insertion of ship opening, 17b ... gas communication hole part for ship opening, 18 ... opening for sensor insertion , 19 ... Gas communication hole, 20 ... Outer pipe member, 21 ... Front half or inlet part of outer pipe member, 23 ... Rear half part or outlet part of outer pipe member, 24 ... Outer exhaust passage (gap space), 24a ... Outer side A portion of the exhaust passage having a relatively large cross-sectional area, P1 to P4, which are exhaust ports of a multi-cylinder engine.

Claims (3)

An exhaust system having a dual-structure exhaust collecting portion for collecting a plurality of branch pipes corresponding to exhaust ports of each cylinder of a multi-cylinder engine,
The dual structure exhaust collecting portion includes an inner pipe member having two or more inlet portions and a single outlet portion, and constructing an inner exhaust passage for collecting two or more branch pipes into one, and the inner pipe member And an outer pipe member that constructs an outer exhaust passage that collects other branch pipes together in the outer peripheral area of the inner pipe member,
The outlet portion of the inner tube member is formed in a single tube, the outlet portion of the outer tube member surrounding the single tube outlet portion is also formed in a single tube, and the single tube outlet portion of the inner tube member is an outer tube. It is arranged eccentrically with respect to the single tubular outlet of the tube member,
Wherein the exhaust collector of a dual structure, gas sensor, so as to penetrate the outer pipe member and the inner pipe member, and, the cross-sectional area by the eccentric arrangement of the outer gas exhaust path at the outlet portion of the exhaust collector An exhaust system for a multi-cylinder engine, characterized in that it is provided so as to occupy a relatively large portion . The exhaust device for a multi-cylinder engine according to claim 1 , wherein an opening for inserting the gas sensor is formed in a single tubular outlet of the inner tube member. A single tubular outlet portion of the inner tube member, according to claim 1, characterized in that an opening for inserting the gas sensor, the gas hole located on the upstream side of the opening is formed Exhaust system for multi-cylinder engines.

Images