JP2013002302A - Exhaust system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly discharge exhaust gas from a bypass passage.SOLUTION: This exhaust system includes a first bypass passage 271 and a second bypass passage 272 (a bypass passage 27) respectively connected to an exhaust gas outlet passage by bypassing an exhaust gas passage for supplying the exhaust gas to a turbine wheel 21 from a first scroll passage 241 and a second scroll passage 242, and a waste gate valve 28 for opening-closing the bypass passage 27 by opening or press-fitting a valve element on or to an outlet end surface of the bypass passage 27. In the outlet end surface 29 of the bypass passage 27, an outer peripheral wall end surface 294 being the outlet end surface of an outer peripheral wall 274 for constituting an outer peripheral surface of the bypass passage 27, is formed in a circumferential shape. A partition wall end surface 293 being the outlet end surface of a partition wall 273 formed in a boundary of the bypass passage 27, is formed in an S shape, and its both ends are connected to the outer peripheral wall end surface 294.

Description

  The present invention relates to an exhaust system for an internal combustion engine including a twin scroll supercharger in which two scroll passages are formed around a turbine wheel.

  2. Description of the Related Art Conventionally, a twin scroll type turbocharger in which two scroll passages are formed around a turbine wheel has been known in order to avoid exhaust interference of an engine mounted on a vehicle and increase the rotational efficiency of the turbine wheel.

  Further, in the twin scroll turbocharger, in order to adjust the amount of exhaust gas supplied to the turbine wheel, the exhaust gas passage for supplying exhaust gas from the two scroll passages to the turbine wheel is bypassed, Two bypass passages connected to the exhaust gas outlet passage are formed, and a waste gate valve for opening and closing the two bypass passages is provided (see Patent Document 1).

JP 2006-348894 A

  However, the twin scroll turbocharger described in Patent Document 1 has a problem in that a time required for warming up the catalyst at the time of starting increases because pressure loss occurs in the bypass passage. This pressure loss is mainly due to the fact that turbulence is generated by the collision of the exhaust gas flowing through the bypass passage with the partition wall formed at the boundary between the two bypass passages.

  That is, when the engine is started, the catalyst wheel is warmed up by avoiding the turbine wheel having a large heat capacity, opening the wastegate valve, and exhausting exhaust gas toward the catalyst via the bypass passage. As the pressure loss in the bypass passage increases, the pressure (flow rate) of the exhaust gas discharged toward the catalyst decreases, and the period required for catalyst warm-up increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an exhaust device for an internal combustion engine that can smoothly exhaust exhaust gas from a bypass passage.

  In order to solve the above problems, an exhaust device for an internal combustion engine according to the present invention is configured as follows.

  That is, an exhaust system for an internal combustion engine according to the present invention is an exhaust system for an internal combustion engine including a twin scroll type supercharger in which two scroll passages are formed around a turbine wheel. By bypassing the exhaust gas passage for supplying exhaust gas to the turbine wheel, the valve body is opened or pressure-bonded to the two bypass passages connected to the exhaust gas outlet passage and the outlet end faces of the two bypass passages, respectively. A wastegate valve that opens and closes the two bypass passages, and of the outlet end surfaces of the two bypass passages, the outlet end surface of the outer peripheral wall constituting the outer peripheral surface of the two bypass passages is substantially circular. The outlet end surface of the partition wall formed at the boundary between the two bypass passages is in contact with the outlet end surface of the outer peripheral wall at two points. It is, is characterized in that it is formed into a linear shape including a curve protruding against the bypass passage of at least one side.

  According to the exhaust system for an internal combustion engine having such a configuration, the exhaust gas in the two scroll passages bypasses the exhaust gas passage for supplying the exhaust gas to the turbine wheel via the two bypass passages, respectively. The exhaust gas outlet passage can be discharged. Further, the wastegate valve opens and closes the two bypass passages by opening or pressing the valve body on the outlet end surfaces of the two bypass passages. Of the outlet end faces of the two bypass passages, the outlet end face of the outer peripheral wall constituting the outer peripheral face of the two bypass passages is formed in a substantially circumferential shape, so that the wastegate valve has a compact configuration. Can be realized. Further, the outlet end face of the partition wall formed at the boundary between the two bypass passages is connected to the outlet end face of the outer peripheral wall at two points, and is formed in a linear shape including a curve protruding from at least one of the bypass passages. Therefore, the exhaust gas can be discharged smoothly from the bypass passage. Therefore, the period required for catalyst warm-up can be shortened.

  That is, when the exhaust gas flowing through one of the two bypass passages collides with a partition wall formed at the boundary between the two bypass passages to generate a turbulent flow, the two bypass passages By forming the outlet end face of the partition wall formed at the boundary into a line including a curve protruding with respect to the other bypass passage, it is possible to prevent the occurrence of turbulent flow, so that exhaust gas can be smoothly discharged from the bypass passage. Can be discharged.

  In the exhaust system for an internal combustion engine according to the present invention, the outlet end face of the partition wall formed at the boundary between the two bypass passages is formed in a substantially S shape, and both ends thereof are connected to the outlet end face of the outer peripheral wall. It is preferable.

  According to the exhaust system for an internal combustion engine having such a configuration, the outlet end surface of the partition wall formed at the boundary between the two bypass passages is formed in a substantially S shape, and both ends thereof are connected to the outlet end surface of the outer peripheral wall. Therefore, exhaust gas can be discharged more smoothly from the bypass passage. Therefore, the period required for catalyst warm-up can be further shortened. In addition, when the partition wall is expanded by exhaust heat, the stress acting on the partition wall end can be reduced.

  The exhaust system for an internal combustion engine according to the present invention further includes a catalyst disposed in the exhaust gas outlet passage, wherein the two bypass passages respectively exhaust gas discharged from the two bypass passages. It is preferably formed so as to be discharged toward the catalyst.

  According to the exhaust device for an internal combustion engine having such a configuration, a catalyst is disposed in the exhaust gas outlet passage, and the two bypass passages respectively discharge exhaust gas discharged from the two bypass passages. Since it is formed so as to be discharged toward the catalyst, the period required for catalyst warm-up can be further shortened.

  The exhaust system for an internal combustion engine according to the present invention further includes an exhaust sensor disposed in the exhaust gas outlet passage, wherein the two bypass passages respectively discharge exhaust gas discharged from the two bypass passages. It is preferably formed to discharge toward the exhaust sensor.

  According to the exhaust device for an internal combustion engine having such a configuration, the two bypass passages are formed to discharge the exhaust gas discharged from the two bypass passages toward the exhaust sensor, respectively. The detection sensitivity in the exhaust sensor can be increased. Therefore, since the control accuracy of the engine can be further improved, the fuel consumption can be further improved, and the emission amount of the regulated substance in the exhaust gas can be further reduced.

  In the exhaust system for an internal combustion engine according to the present invention, it is preferable that the exhaust sensor is disposed at a position close to the downstream side of the waste gate valve.

  According to the exhaust device for an internal combustion engine having such a configuration, since the exhaust sensor is disposed at a position close to the downstream side of the waste gate valve, the detection sensitivity of the exhaust sensor can be further increased. Therefore, since the control accuracy of the engine can be further improved, the fuel consumption can be further improved, and the emission amount of the regulated substance in the exhaust gas can be further reduced.

  According to the exhaust system for an internal combustion engine according to the present invention, the exhaust gas in the two scroll passages bypasses the exhaust gas passage for supplying the exhaust gas to the turbine wheel via the two bypass passages, respectively. The exhaust gas outlet passage can be discharged. Further, the wastegate valve opens and closes the two bypass passages by opening or pressing the valve body on the outlet end surfaces of the two bypass passages. Of the outlet end surfaces of the two bypass passages, the outlet end surface of the outer peripheral wall constituting the outer peripheral surface of the two bypass passages is formed in a substantially circumferential shape and formed at the boundary between the two bypass passages. The outlet end face of the partition wall is connected to the outlet end face of the outer peripheral wall at two points, and is formed in a linear shape including a curve protruding at least with respect to the bypass passage on one side. Can be discharged.

It is a block diagram which shows an example of a structure of the intake / exhaust system by which the exhaust apparatus of the internal combustion engine which concerns on this invention is arrange | positioned. It is a side view which shows an example of the external appearance of a scroll channel | path and an exhaust gas exit channel | path. It is sectional drawing which shows an example of the BB cross section of FIG. It is sectional drawing which shows an example of the AA cross section of FIG. It is sectional drawing which shows an example of the CC cross section of FIG. It is a figure which shows an example of the exit end surface of a bypass channel. It is a graph which shows an example of a change of pressure loss. It is a figure which shows another example of the exit end surface of a bypass channel. It is a figure which shows another example of the exit end surface of a bypass channel.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

-Engine 1 intake and exhaust system-
FIG. 1 is a configuration diagram showing an example of a configuration of an intake and exhaust system in which an exhaust device for an internal combustion engine according to the present invention is arranged. First, the overall configuration of the intake and exhaust system of the engine 1 will be described with reference to FIG. The engine 1 is, for example, a 4-cylinder (1st cylinder to 4th cylinder) gasoline engine, and an intake manifold 2 for distributing intake air to each cylinder is connected to a cylinder head. Here, the engine 1 corresponds to an “internal combustion engine” described in the claims.

  An intake passage 4 is connected to the inlet of the intake manifold 2 to take air from the atmosphere and lead it to the intake manifold 2. An air cleaner 5 is disposed at the inlet of the intake passage 4. A throttle valve 6 that adjusts the intake air amount of the engine 1 is disposed upstream of the intake manifold 2 (upstream of the intake flow).

  On the other hand, the exhaust gas from each cylinder (the first cylinder to the fourth cylinder) of the engine 1 is discharged from the exhaust port of each cylinder to the first exhaust passage 31 to the fourth exhaust passage 34, respectively. In addition, the first exhaust passage 31 and the fourth exhaust passage 34 merge on the downstream side and are connected to the first relay passage 35. Further, the second exhaust passage 32 and the third exhaust passage 33 merge on the downstream side and are connected to the second relay passage 36. The first exhaust passage 31 to the fourth exhaust passage 34, the first relay passage 35, and the second relay passage 36 constitute an exhaust manifold.

  The first relay passage 35 and the second relay passage 36 are connected to a first scroll passage 241 and a second scroll passage 242 (see FIGS. 2 and 3), respectively. The first scroll passage 241 and the second scroll passage 242 correspond to “two scroll passages” recited in the claims. Exhaust gas supplied to the turbine wheel 21 from the first scroll passage 241 and the second scroll passage 242 (see FIGS. 2 and 3) is discharged to the exhaust gas outlet passage 8.

  As shown in FIG. 2, the A / F sensor 81 is inserted into the exhaust gas outlet passage 8 at a position close to the downstream side of a later-described wastegate valve 28 from the side surface (the front side in FIG. 2). Is arranged. The A / F sensor 81 has a first bypass passage when exhaust gas discharged from the first scroll passage 241 and the second scroll passage 242 via the turbine wheel 21 and a wastegate valve 28 described later are in an open state. 271 and a sensor that detects an air-fuel ratio with the exhaust gas discharged from the second bypass passage 272. The A / F sensor 81 corresponds to the exhaust sensor described in the claims.

A three-way catalyst 9 is connected to the downstream side of the exhaust gas outlet passage 8. The three-way catalyst 9 performs oxidation of CO, HC and reduction of NOx in the exhaust gas discharged from the engine 1 into the exhaust gas outlet passage 8, thereby converting them into harmless CO ₂ , H ₂ O, N ₂ . By doing so, the exhaust gas is purified. Here, the three-way catalyst 9 corresponds to a “catalyst” described in the claims.

  In the present embodiment, the case where the engine 1 is a gasoline engine and the catalyst is a three-way catalyst 9 will be described. However, the engine 1 is a diesel engine and the catalyst is a DPF (Diesel Particulate Filter) or the like. Form may be sufficient.

-Turbocharger 20-
A turbocharger 20 is disposed in the intake / exhaust system of the engine 1. The turbocharger 20 includes a turbine wheel 21, a compressor impeller 22, and a connecting shaft 23. The turbine wheel 21 is disposed in the turbine housing 24 connected to the downstream end portions of the first relay passage 35 and the second relay passage 36, and is rotated by the energy of the exhaust. The compressor impeller 22 is disposed in the intake passage 4. The connecting shaft 23 connects the turbine wheel 21 and the compressor impeller 22 integrally. Here, the turbocharger 20 corresponds to a “supercharger” described in the claims.

  The turbine wheel 21 disposed in the turbine housing 24 is rotationally driven by the energy of the exhaust gas, and the compressor impeller 22 disposed in the intake passage 4 is rotationally driven accordingly. The intake air is supercharged by the rotation of the compressor impeller 22, and the supercharged air is forcibly sent into the combustion chamber of each cylinder of the engine 1. Note that an intercooler 7 for cooling air supercharged by the compressor impeller 22 is interposed in the intake passage 4 on the downstream side (downstream of the intake air flow) of the compressor impeller 22.

-Bypass passage 27 and waste gate valve 28-
An exhaust gas passage for supplying exhaust gas to the turbine wheel 21 (here, the first scroll passage 241 and the first scroll passage 241) is provided at the downstream end of the first relay passage 35 and the second relay passage 36 (see FIGS. 2 and 3). The first scroll passage 271 and the second bypass passage 272 connected to the exhaust gas outlet passage 8 are connected to bypass the second scroll passage 242). Here, the first bypass passage 271 and the second bypass passage 272 correspond to “two bypass passages” recited in the claims.

  Further, a wastegate valve 28 is disposed on the outlet end face 29 (see FIGS. 3 to 5) of the first bypass passage 271 and the second bypass passage 272 so as to be freely opened and closed. The wastegate valve 28 is a valve for opening and closing the first bypass passage 271 and the second bypass passage 272, and by opening or press-bonding a plate-like valve body to the outlet end surface 29 (see FIGS. 3 to 5), The first bypass passage 271 and the second bypass passage 272 are opened and closed. The wastegate valve 28 is driven to open and close by a drive mechanism (not shown), and this drive mechanism drives the wastegate valve 28 to open and close in accordance with an instruction from an ECU (Electronic Control Unit) (not shown).

  FIG. 2 is a side view showing an example of the appearance of the first scroll passage 241, the second scroll passage 242 and the exhaust gas outlet passage 8. FIG. 3 is a cross-sectional view showing an example of the BB cross section of FIG. FIG. 4 is a cross-sectional view showing an example of the AA cross section of FIG. FIG. 5 is a cross-sectional view showing an example of the CC cross section of FIG. Hereinafter, the scroll passages 241 and 242, the bypass passages 271 and 272, and the wastegate valve 28 will be described with reference to FIGS. 2 to 5.

  First, as shown in FIGS. 2 and 3, the first scroll passage 241 and the second scroll passage 242 are formed around the turbine wheel 21 in the turbine housing 24. The first scroll passage 241 is a passage for supplying exhaust gas from the first and fourth cylinders of the engine 1 to the turbine wheel 21. The second scroll passage 242 is the second and third cylinders of the engine 1. This is a passage for supplying exhaust gas from the turbine wheel 21 (see FIG. 1).

  That is, the exhaust gas from the first cylinder and the fourth cylinder of the engine 1 passes through the first exhaust passage 31 and the fourth exhaust passage 34 respectively, and then sequentially passes through the first relay passage 35 and the first scroll passage 241. Via, it is supplied to the turbine wheel 21. Further, exhaust gas from the second cylinder and the third cylinder of the engine 1 passes through the second exhaust passage 32 and the third exhaust passage 33, respectively, and then sequentially passes through the second relay passage 36 and the second scroll passage 242. Via, it is supplied to the turbine wheel 21. Thus, a so-called “twin scroll type” turbocharger 20 is configured.

  In addition, as shown in FIG. 2, the exhaust gas discharged from the first bypass passage 271 and the second bypass passage 272 (collectively referred to as “bypass passage 27”) is the waste gate valve 28 that is opened. Is discharged in the direction of the broken arrow VA along the surface of the plate-like valve body (lower side in FIG. 2). That is, the bypass passage 27 is formed to discharge the exhaust gas discharged from the bypass passage 27 toward the A / F sensor 81 and the three-way catalyst 9. Further, as shown in FIG. 2, the A / F sensor 81 is arranged at a position close to the downstream side of the waste gate valve 28 in a manner of being inserted from the side surface (the front side in FIG. 2).

  In this manner, as indicated by the broken line arrow VA in FIG. 2, the bypass passage 27 is formed to discharge the exhaust gas discharged from the bypass passage 27 toward the A / F sensor 81. The detection sensitivity in the / F sensor 81 can be increased. Therefore, since the control accuracy of the engine 1 can be further improved, the fuel consumption of the engine 1 can be improved and the emission amount of regulated substances such as CO, HC, NOx contained in the exhaust gas can be reduced.

  In the present embodiment, the case where the bypass passage 27 discharges exhaust gas toward the A / F sensor 81 will be described. However, the tubular shape that guides the exhaust gas discharged from the bypass passage 27 to the A / F sensor 81. The form provided with a member may be sufficient. In this case, the detection sensitivity of the A / F sensor 81 can be ensured, and the degree of freedom of the arrangement position of the A / F sensor 81 can be increased.

  Further, as shown in FIG. 2, since the A / F sensor 81 is disposed at a position close to the downstream side of the waste gate valve 28, the detection sensitivity of the A / F sensor 81 can be further increased. Therefore, since the control accuracy of the engine 1 can be further improved, the fuel consumption of the engine 1 can be further improved, and the emission amount of regulated substances such as CO, HC, NOx contained in the exhaust gas can be further reduced. it can.

  In the present embodiment, the case where the A / F sensor 81 is disposed at a position close to the downstream side of the waste gate valve 28 has been described. However, the exhaust gas discharged from the bypass passage 27 is converted into the A / F sensor. The form provided with the cylindrical member which guides to 81 may be sufficient. In this case, the detection sensitivity of the A / F sensor 81 can be ensured, and the degree of freedom of the arrangement position of the A / F sensor 81 can be increased.

-Septum 273-
Further, as shown in FIGS. 3 and 4, the outlet end surfaces 29 of the first bypass passage 271 and the second bypass passage 272 are an exhaust hole 291 which is an end surface on the outlet side of the first bypass passage 271 and a second bypass passage. An exhaust hole 292 that is an end face on the outlet side of the 272, a partition end face 293 that is an exit end face of the partition 273 (see FIG. 5) formed at the boundary between the first bypass passage 271 and the second bypass passage 272, and a first bypass And an outer peripheral wall end surface 294 that is an outlet end surface of the outer peripheral wall 274 (see FIG. 5) constituting the outer peripheral surfaces of the passage 271 and the second bypass passage 272.

  The outer peripheral wall end surface 294 is formed in a circumferential shape, and the partition wall end surface 293 is formed in an S shape. The exhaust hole 291 is formed in the shape of a slanting ball that is widened on the lower side, and the exhaust gas from the first relay passage 35 passes through the first bypass passage 271 (see FIG. 5) as indicated by the broken arrow V1 in FIG. Via, it is discharged along the lower surface of the exhaust hole 291 to the front side of the sheet of FIG. Further, the exhaust hole 292 is formed in a slanted ball shape that widens upward, and the exhaust gas from the second relay passage 36 is supplied to the second bypass passage 272 (see FIG. 5) as indicated by the broken line arrow V2 in FIG. 3 is discharged along the upper side surface of the exhaust hole 292 to the front side of the sheet of FIG.

  Further, as shown in FIG. 5, the first bypass passage 271 is formed with an inlet on the outer peripheral side (the upper end side in FIG. 5) of the first scroll passage 241, and the second bypass passage 272 is connected to the second scroll passage 242. An inlet is formed on the outer peripheral side (the upper end side in FIG. 5). Further, the outer peripheral wall 274 has an inlet of the outer peripheral wall 274 formed on the outer peripheral side (the upper end side in FIG. 5) of the first scroll passage 241 and the outer peripheral end side (the upper end side in FIG. 5) of the second scroll passage 242. Has been. Further, the partition wall 273 has a flow of exhaust gas that passes through the first bypass passage 271 and a flow of exhaust gas that passes through the second bypass passage 272 at the boundary between the first bypass passage 271 and the second bypass passage 272. It is formed in a manner that does not inhibit as much as possible.

  In other words, the partition wall 273 is a position where the pressure losses ΔP1 and ΔP2 (see FIG. 7) in the first bypass passage 271 and the second bypass passage 272 when the wastegate valve 28 is open are equal to or less than a preset threshold value. And formed into a shape. Specifically, the partition wall 273 is configured by a smooth curved surface so that turbulent flow does not occur when exhaust gas passes through the first bypass passage 271 and the second bypass passage 272, respectively. In other words, the exhaust gas passing through the first bypass passage 271 and the second bypass passage 272 is exhausted along the inner peripheral surfaces of the first bypass passage 271 and the second bypass passage 272 including the partition wall 273, respectively. It is guided to the hole 292 and is smoothly discharged from the exhaust hole 291 and the exhaust hole 292.

  Further, the partition wall 273 is formed in a position and a shape that substantially match the pressure losses ΔP1 and ΔP2 in the first bypass passage 271 and the second bypass passage 272 when the wastegate valve 28 is open (see FIG. 7). . Specifically, as will be described later with reference to FIGS. 6 and 7, conventionally, the shape of the partition formed between the first bypass passage 271 and the second bypass passage (particularly on the outlet side of the partition wall). The pressure loss ΔP2 in the second bypass passage 272 was larger than the pressure loss ΔP1 in the first bypass passage 271 due to the shape of the end face of the partition wall which is the end face. Accordingly, the position and shape of the partition wall 273 according to the present invention are set so that the pressure loss ΔP2 in the second bypass passage 272 is reduced as compared with the prior art and substantially matches the pressure loss ΔP1 in the first bypass passage 271. It is.

  In this way, the partition wall 273 formed at the boundary between the first bypass passage 271 and the second bypass passage 272 is a pressure loss in the first bypass passage 271 and the second bypass passage 272 when the wastegate valve 28 is open. Since ΔP1 and ΔP2 are formed at positions and shapes that are equal to or less than a preset threshold value, exhaust gas can be discharged smoothly from the first bypass passage 271 and the second bypass passage 272, so that the catalyst warm-up It is possible to shorten the period required for the process.

  That is, when the engine 1 is started, the turbine wheel 21 having a large heat capacity is avoided, the waste gate valve 28 is opened, and the exhaust gas is discharged toward the three-way catalyst 9 via the bypass passage 27, thereby three-way. Although the catalyst 9 is warmed up, the pressure (flow rate) of the exhaust gas discharged toward the three-way catalyst 9 decreases as the pressure loss ΔP1, ΔP2 in the bypass passage 27 increases, so that it is necessary to warm up the catalyst. The period increases. Therefore, as described above, the exhaust gas can be discharged smoothly from the first bypass passage 271 and the second bypass passage 272, so that the period required for catalyst warm-up can be shortened.

  Further, since the outer peripheral wall end surface 294 that is the outlet end surface of the outer peripheral wall 274 constituting the outer peripheral surfaces of the first bypass passage 271 and the second bypass passage 272 is formed in a circumferential shape, the waste gate valve 28 can be made compact. It can be realized with a configuration.

  In the present embodiment, the case where the partition wall 273 is formed in a position and shape where the pressure loss ΔP1, ΔP2 is equal to or less than a preset threshold value has been described. However, at least a part of the partition wall 273 including the partition wall end surface 293 is What is necessary is just the form currently formed in the position and shape which make pressure loss (DELTA) P1, (DELTA) 2 below a predetermined threshold value.

  Further, as described above with reference to the broken line arrow VA in FIG. 2, the bypass passage 27 is formed to discharge the exhaust gas discharged from the bypass passage 27 toward the three-way catalyst 9. The period required for warming up the catalyst can be further shortened.

  In the present embodiment, the case where the exhaust gas discharged from the bypass passage 27 is discharged toward the three-way catalyst 9 will be described. However, the cylinder that guides the exhaust gas discharged from the bypass passage 27 to the three-way catalyst 9 is described. A form provided with a shaped member or the like may be used. In this case, the period required for catalyst warm-up can be shortened, and the degree of freedom of the arrangement position of the three-way catalyst 9 can be increased.

  Next, the effect of making the shape of the partition wall end surface 293 in the outlet end surface 29 of the bypass passage 27 S-shaped will be described in comparison with the conventional partition wall end surface 293A with reference to FIG. FIG. 6 is a diagram illustrating an example of the outlet end surface 29 of the bypass passage 27. FIG. 6A is a view showing an example of the outlet end face 29 of the bypass passage 27 in the present invention, and FIG. 6B is a view showing an example of the outlet end face 29A of the conventional bypass passage.

  As shown in FIG. 6A, the outlet end surface 29 of the bypass passage 27 in the present invention is an exhaust hole 291 that is an end surface on the outlet side of the first bypass passage 271 and an end surface on the outlet side of the second bypass passage 272. An exhaust hole 292, a partition wall end surface 293 that is an end surface on the outlet side of the partition wall 273, and an outer peripheral wall end surface 294 that is an end surface on the outlet side of the outer peripheral wall 274 (see FIG. 5) are provided. The outer peripheral wall end surface 294 is formed in a circumferential shape. Further, the partition wall end surface 293 is connected to the outer peripheral wall end surface 294 at two points, and is formed in a linear shape including a curve that protrudes with respect to at least one bypass passage (here, the first bypass passage 271). Specifically, the partition wall end surface 293 is formed in an S shape in which both ends are connected to the outer peripheral wall end surface 294. The exhaust hole 291 is formed in the shape of a slanted ball that expands on the lower side. In addition, the exhaust hole 292 is formed in the shape of a slanted ball that widens upward.

  On the other hand, as shown in FIG. 6B, the outlet end surface 29A of the conventional bypass passage is an exhaust hole 291A that is an end surface on the outlet side of the first bypass passage and an exhaust surface that is an end surface on the outlet side of the second bypass passage. It has a hole 292A, a partition wall end surface 293A that is an end surface on the outlet side of the partition wall, and an outer peripheral wall end surface 294A that is an end surface on the outlet side of the outer peripheral wall. The outer peripheral wall end surface 294A is formed in a circumferential shape. Further, the partition wall end surface 293A is formed in a straight line (substantially I shape). Further, the exhaust holes 291A and the exhaust holes 292 are formed in a semicircular shape.

  As shown in FIG. 6B, when the partition end face 293A is formed in a straight line (substantially I shape), the outlet end face 29A is configured when the partition end face 293A is thermally expanded by heat from the exhaust gas. In the cylindrical outer peripheral member, the stress acts on the position (upper and lower ends in FIG. 6B) where the partition wall end surface 293A is connected. This stress may cause the bypass passage to be deformed.

  On the other hand, as shown in FIG. 6A, when the partition wall end surface 293 is formed in an S shape, the partition wall 273 is left and right even if the partition wall end surface 293 is thermally expanded by heat from the exhaust gas. The stress acting on the position where the partition wall end surface 293 is connected (upper and lower ends in FIG. 6B) is reduced. Therefore, it is possible to prevent the bypass passage 27 from being deformed.

  In the present embodiment, the case where the partition wall end surface 293 is formed in an S-shape will be described, but it is sufficient that the partition wall end surface has a smooth curve. For example, the form (refer FIG. 9) by which the partition end surface 293 was formed in the substantially C shape may be sufficient.

  FIG. 7 is a graph showing an example of changes in pressure loss. The horizontal axis represents the pressure loss ΔP1 of the second bypass passage 272, and the vertical axis represents the pressure loss ΔP2 of the first bypass passage 271. The graph G1 is a graph showing the relationship between the pressure loss ΔP1 and the pressure loss ΔP2 when the partition wall end surface 293A is formed in a straight line (substantially I shape) (see FIG. 6B). The graph G2 is a graph showing the relationship between the pressure loss ΔP1 and the pressure loss ΔP2 when the partition wall end surface 293 is formed in an S shape (see FIG. 6A).

  As shown in the graph G1, when the partition wall end surface 293A is formed in a straight line (substantially I shape) (conventional case), a turbulent flow is generated at the end surface on the outlet side of the second bypass passage. The loss ΔP2 becomes larger than the pressure loss ΔP1. On the other hand, when the partition wall end surface 293 is formed in an S shape (in the case of the present invention), the generation of turbulent flow at the end surface on the outlet side of the second bypass passage 272 is suppressed, so that the pressure loss ΔP2 is substantially the same value as the pressure loss ΔP1.

  In this way, as shown in FIG. 2, the A / F sensor 81 is disposed in the exhaust gas outlet passage 8, and the partition wall 273 formed at the boundary between the first bypass passage 271 and the second bypass passage 272 includes: Since the pressure loss ΔP1 and ΔP2 in the first bypass passage 271 and the second bypass passage 272 when the waste gate valve 28 is in the open state are formed at positions and shapes that substantially coincide with each other, the first bypass passage 271 and the second bypass passage 271 are formed. Of the exhaust gases discharged from the passages 272, the amount of exhaust gas reaching the A / F sensor 81 can be made substantially the same. Therefore, variation in detection sensitivity between the cylinders in the A / F sensor 81 is reduced, so that the control accuracy of the engine 1 can be improved, so that the fuel consumption of the engine 1 is improved and the CO, Emissions of regulated substances such as HC and NOx can be reduced.

-Other shapes of partition wall end face-
Next, with reference to FIGS. 8 and 9, another shape of the end face on the outlet side of the partition wall 273 formed at the boundary between the first bypass passage 271 and the second bypass passage 272 will be described.

  In the present embodiment, the case where the partition wall end surface 293 is formed in an S shape has been described. However, as illustrated in FIG. 8, the partition wall end surfaces 293B and 293C may be formed in a substantially S shape. FIG. 8 is a view showing another example of the outlet end face of the bypass passage 27. 8 (a) and 8 (b) are views showing other examples (outlet end surface 29B and outlet end surface 29C) of the outlet end surface of the bypass passage 27 in the present invention, respectively.

  The outlet end surface 29B shown in FIG. 8A includes an exhaust hole 291B that is an end surface on the outlet side of the first bypass passage 271, an exhaust hole 292B that is an end surface on the outlet side of the second bypass passage 272, and the first bypass passage. A partition wall end surface 293B which is an outlet end surface of the partition wall 273 (see FIG. 5) formed at the boundary between the 271 and the second bypass passage 272, and an outer peripheral wall 274 constituting the outer peripheral surface of the first bypass passage 271 and the second bypass passage 272. And an outer peripheral wall end surface 294B which is an outlet end surface (see FIG. 5).

  Similarly, the outlet end surface 29C shown in FIG. 8B includes an exhaust hole 291C which is an end surface on the outlet side of the first bypass passage 271, an exhaust hole 292C which is an end surface on the outlet side of the second bypass passage 272, and A partition wall end surface 293C that is an outlet end surface of the partition wall 273 (see FIG. 5) formed at the boundary between the first bypass channel 271 and the second bypass channel 272, and an outer peripheral surface of the first bypass channel 271 and the second bypass channel 272 are configured. And an outer peripheral wall end surface 294C which is an outlet end surface of the outer peripheral wall 274 (see FIG. 5).

  The partition wall end surface 293 shown in FIG. 6A is formed in an S shape, whereas the partition wall end surface 293B shown in FIG. 8A has a central portion of the partition wall end surface 293 shown in FIG. Since it is formed in a substantially S-shape that is linear, the same effect as the partition wall end surface 293 shown in FIG. Similarly, the partition wall end surface 293C shown in FIG. 8B is formed in a substantially S shape in which the partition wall end surface 293 shown in FIG. 6A is bent, so that the partition wall end surface shown in FIG. The same effect as 293 is produced.

  Further, in the present embodiment, the case where the partition wall end surface 293 is formed in an S shape has been described. However, as illustrated in FIG. 9, the partition wall end surfaces 293D and 293E include first bypass passages 271 (exhaust holes 291D and 291E). Any form including a curved line protruding to the side may be used. FIG. 9 is a view showing still another example of the outlet end face of the bypass passage 27. FIG. 9A and FIG. 9B are diagrams showing other examples (outlet end surface 29D and outlet end surface 29E) of the outlet end surface of the bypass passage 27 in the present invention, respectively.

  The outlet end surface 29D shown in FIG. 9A includes an exhaust hole 291D that is an end surface on the outlet side of the first bypass passage 271, an exhaust hole 292D that is an end surface on the outlet side of the second bypass passage 272, and the first bypass passage. A partition wall end surface 293D that is an outlet end surface of the partition wall 273 (see FIG. 5) formed at the boundary between the 271 and the second bypass passage 272, and an outer peripheral wall 274 that forms the outer peripheral surface of the first bypass passage 271 and the second bypass passage 272. And an outer peripheral wall end surface 294D which is an outlet end surface (see FIG. 5).

  Similarly, the outlet end surface 29E shown in FIG. 9B includes an exhaust hole 291E that is an end surface on the outlet side of the first bypass passage 271; an exhaust hole 292E that is an end surface on the outlet side of the second bypass passage 272; A partition wall end surface 293E that is an exit end surface of the partition wall 273 (see FIG. 5) formed at the boundary between the first bypass channel 271 and the second bypass channel 272 and an outer peripheral surface of the first bypass channel 271 and the second bypass channel 272 are configured. And an outer peripheral wall end surface 294E which is an outlet end surface of the outer peripheral wall 274 (see FIG. 5).

  The partition wall end surface 293 shown in FIG. 6A is formed in an S shape, whereas the partition wall end surface 293D shown in FIG. 9A is a first bypass of the partition wall end surface 293 shown in FIG. Since it is formed in a substantially S shape with a large amount of protrusion toward the passage 271 (exhaust hole 291), the same effect as the partition wall end surface 293 shown in FIG.

  On the other hand, the partition wall end surface 293E shown in FIG. 9B is formed in a substantially C shape including a curve protruding toward the first bypass passage 271 (exhaust hole 291E), and therefore the exhaust gas flowing through the second bypass passage 272. It is possible to prevent the gas from colliding with the partition wall 273 and generating a turbulent flow. Therefore, exhaust gas can be discharged smoothly from the second bypass passage 272, and the same effect as the partition wall end surface 293 shown in FIG.

-Other embodiments-
In the present embodiment, the case has been described in which the partition wall 273 is formed in a position and shape in which the pressure losses ΔP1 and ΔP2 in the first bypass passage 271 and the second bypass passage 272 are equal to or less than a preset threshold value. It suffices if the first bypass passage 271 and the second bypass passage 272 are formed in positions and shapes that make the pressure losses ΔP1, ΔP2 equal to or less than a preset threshold value.

  In the present embodiment, the bypass passage 27 discharges the exhaust gas toward the A / F sensor 81 and the three-way catalyst 9, but the bypass passage 27 discharges the exhaust gas from the A / F sensor 81 or A form of discharging toward the three-way catalyst 9 may be employed.

In the present embodiment, the case where the exhaust sensor is the A / F sensor 81 has been described. However, the exhaust sensor may be another type of sensor (for example, an O ₂ sensor).

  In the present embodiment, the case where the engine 1 has four cylinders (first cylinder to fourth cylinder) has been described, but the engine 1 may have another number of cylinders (for example, six cylinders).

  In the present embodiment, the case where the partition wall 273 is formed at a position and shape that substantially matches the pressure losses ΔP1, ΔP2 has been described. However, at least a part of the partition wall 273 including the partition wall end surface 293 has the pressure loss ΔP1, ΔP2. Any form may be used as long as the positions and shapes are substantially matched.

  The present invention can be used for an exhaust device of an internal combustion engine including a twin scroll type supercharger in which two scroll passages are formed around a turbine wheel.

1 engine (internal combustion engine)
2 Intake manifold 20 Turbocharger (supercharger)
21 Turbine wheel 22 Compressor impeller 23 Connecting shaft 24 Turbine housing 241 First scroll passage (scroll passage)
242 Second scroll passage (scroll passage)
27 Bypass passage 271 First bypass passage 272 Second bypass passage 273 Bulkhead 274 Outer wall 28 Westgate valve 29, 29B, 29C, 29D, 29E Outlet end face 291, 291B, 291C, 291D, 291E Exhaust hole 292, 292B, 292C, 292D, 292E Exhaust hole 293, 293B, 293C, 293D, 293E Bulkhead end face 294, 294B, 294C, 294D, 294E Outer peripheral wall end face 4 Intake passage 5 Air cleaner 6 Throttle valve 7 Intercooler 8 Exhaust gas outlet passage 81 A / F sensor ( Exhaust sensor)
9 Three-way catalyst (catalyst)

Claims (5)

An exhaust system for an internal combustion engine comprising a twin scroll type supercharger in which two scroll passages are formed around a turbine wheel,
Bypassing an exhaust gas passage for supplying exhaust gas from the two scroll passages to the turbine wheel, respectively, two bypass passages connected to an exhaust gas outlet passage;
A wastegate valve that opens or closes the two bypass passages by opening or crimping a valve body to an outlet end face of the two bypass passages, and
Of the exit end faces of the two bypass passages,
The outlet end surface of the outer peripheral wall constituting the outer peripheral surface of the two bypass passages is formed in a substantially circular shape,
The outlet end face of the partition wall formed at the boundary between the two bypass passages is connected to the outlet end face of the outer peripheral wall at two points, and is formed in a linear shape including a curve protruding from at least one bypass passage. An exhaust system for an internal combustion engine characterized by comprising: The exhaust system for an internal combustion engine according to claim 1,
An exhaust system for an internal combustion engine, wherein an outlet end face of a partition wall formed at a boundary between the two bypass passages is formed in a substantially S shape, and both ends thereof are connected to the outlet end face of the outer peripheral wall. The exhaust system for an internal combustion engine according to claim 1 or 2,
Further comprising a catalyst disposed in the exhaust gas outlet passage;
The exhaust system for an internal combustion engine, wherein the two bypass passages are formed so as to discharge exhaust gases discharged from the two bypass passages toward the catalyst, respectively. The exhaust system for an internal combustion engine according to any one of claims 1 to 3,
An exhaust sensor disposed in the exhaust gas outlet passage;
The exhaust system for an internal combustion engine, wherein the two bypass passages are formed so as to discharge exhaust gases discharged from the two bypass passages toward the exhaust sensor. The exhaust system for an internal combustion engine according to claim 4,
An exhaust system for an internal combustion engine, wherein the exhaust sensor is disposed at a position close to the downstream side of the waste gate valve.

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