JP2010185401A - Exhaust passage structure of multi-cylinder engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently supply exhaust gas to an exhaust turbocharger. <P>SOLUTION: An exhaust passage structure has a collective portion 42 at which downstream sides of more than two independent branch passages 31A-31C (41A-41C) communicating with cylinders different from each other and independent from each other are collected. The exhaust turbocharger 26 is arranged downstream of the collecting part 32. Throttle valves 51A-51C for varying passage opening areas are arranged in the independent branch passages 31A-31C (41A-41C) upstream of the collective portion 42, respectively. The respective throttle valves 51A-51C are each formed with a gap passage part 52 in another independent branch passage direction so that it provides a gap when the throttle valves 51A-51C are fully closed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust passage structure for a multi-cylinder engine.

  In an engine equipped with an exhaust turbocharger, exhaust gases from a plurality of cylinders are gathered in a collecting part via an exhaust manifold, and the exhaust turbocharger is disposed downstream of the collecting part. . In order to operate the exhaust turbocharger efficiently, the exhaust gas immediately after being discharged from the exhaust port, that is, blowdown gas, is supplied to the exhaust turbocharger without reducing the force as much as possible. Is preferable.

In Patent Document 1, an exhaust turbo-type supercharger is disposed downstream of a collecting portion where independent branch passages of the exhaust manifold are gathered. There has been proposed a nozzle valve that is deflected toward the exhaust gas so that exhaust gas is supplied to the exhaust turbocharger as vigorously as possible.
JP 2007-231791 A

  By the way, the exhaust passage on the upstream side of the exhaust turbocharger is branched into a plurality of independent branch passages connected to different cylinders, but the exhaust gas discharged to a certain independent branch passage becomes another independent branch passage. As a result, the momentum of the exhaust gas supplied to the exhaust turbocharger is reduced, making it difficult to operate the exhaust turbocharger efficiently. In the thing of patent document 1, although it has the effect | action which concentrates the exhaust gas supplied to a gathering part so that it may go to an exhaust turbo supercharger, the exhaust gas from a certain independent branch passage goes to another independent branch passage. It will be difficult to prevent it from flowing.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an exhaust passage structure of a multi-cylinder engine that can supply exhaust gas to an exhaust turbocharger more efficiently. It is in.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1 in the claims,
Three or more independent branch passages connected to different cylinders and independent from each other, a collecting portion where the downstream sides of the independent branch passages are gathered together, and an exhaust turbo-type turbocharger disposed downstream of the gathering portion An exhaust passage structure of a multi-cylinder engine having a feeder,
Each of the independent branch passages is provided with a throttle valve for changing the passage opening area on the upstream side of the collecting portion,
Each throttle valve is formed with a gap passage portion in the direction of another independent branch passage so that the throttle valve becomes a gap when fully closed.
It is like that.

  According to the above solution, the exhaust gas ejector effect (suction effect) can be obtained by the exhaust gas flowing through the throttle portion formed by the gap passage portion of the throttle valve. That is, the exhaust gas discharged to a certain independent branch passage has its flow velocity increased by passing through the throttle portion, and flows vigorously toward the exhaust turbocharger side. When the exhaust gas passes through the throttle portion, the suction effect of sucking in the other independent branch passage is exhibited, and the exhaust gas from one independent branch passage is exhausted without being expanded to the other independent branch passage. It will be supplied directly to the turbocharger. Particularly, the suction effect is enhanced by vigorous exhaust gas, that is, blowdown gas immediately after the exhaust port is opened. Also, due to the suction effect, the exhaust gas discharged from a certain cylinder improves the scavenging of the other cylinders and increases the charging efficiency of the other cylinders (improvement of charging efficiency by 10 to 20%). . Furthermore, when dynamic pressure supercharging utilizing exhaust pulsation is obtained, exhaust gas flowing through one independent branch passage is prevented from flowing (expanding) to another independent branch passage, so the exhaust passage volume is reduced. As a result, the effect of dynamic pressure supercharging can be enhanced (the instantaneous flow rate due to the strong blowdown gas can be effectively supplied to the exhaust turbocharger). In summary, the engine torque, particularly the engine torque at low speeds, can be greatly improved. Of course, when a large amount of exhaust gas is discharged, such as during high load and high rotation, the exhaust gas can be discharged well by opening the throttle valve.

  In addition to the above, the gap passage portion is formed in the direction of the other independent branch passage, so that, for example, the exhaust gas contacts the passage wall surface as compared with the case where the gap passage portion is formed in the central portion of the independent branch passage. Therefore, the flow resistance of the exhaust gas is reduced by this amount, which is more preferable for vigorously supplying the exhaust gas to the exhaust turbocharger. Of course, the formation of the gap passage portion in the direction of the other independent branch passage is effective because the exhaust gas flow that obtains the suction effect by passing through this gap passage portion is located close to the other independent branch passage. It is also preferable for further improving the ratio.

A preferred mode based on the above solution is as described in claim 2 and the following claims. That is,
Each of the gap passage portions is formed at a position offset in the direction of the other independent branch passage when the throttle valve is in the closed position (corresponding to claim 2). In this case, the gap passage portion can be formed in the direction of another independent branch passage by a simple method called offset, and the inflow angle to the turbine wheel of the exhaust turbocharger can be made shallower (smaller). This is preferable in preventing or suppressing the situation where the gas is impinged on the wall of the passage.

  The plurality of gap passage portions provided in the throttle valves are arranged in a staggered manner (corresponding to claim 3). In this case, compared with the case where the gap passage portions are arranged in series on the same straight line, it is preferable to make the distance closer to each other and enhance the suction effect. Further, it is possible to easily cope with the case where the gap passage portion is enlarged.

The throttle valve is a butterfly valve;
The gap passage portion is constituted by a notch formed in an outer peripheral edge portion of the butterfly valve.
(Corresponding to claim 4). In this case, the gap passage portion can be configured with a simple structure in which a notch portion is formed in the outer peripheral edge portion of the butterfly valve while the throttle valve having a simple valve structure called a butterfly valve is used.

The downstream end of each of the independent branch passages is connected to the collective portion so as to surround the center of the collective portion,
The gap passage portion is offset and formed at a position toward the center side of the collecting portion.
(Corresponding to claim 5). In this case, the exhaust gas from each independent branch passage is preferable for concentrating the exhaust gas from the central portion of the collecting portion as much as possible, and also preferable for compactly forming the vicinity of the collecting portion.

The engine is an in-line four-cylinder engine in which the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder are arranged in series with each other, and the exhaust of the second and third cylinders that are the two cylinders in the center The processes are set not to be continuous with each other,
The independent branch passage includes a first independent branch passage that communicates with the exhaust port of the first cylinder, a second independent branch passage that communicates with the exhaust ports of the second and third cylinders, and an exhaust port of the fourth cylinder. The third independent branch passage and the three,
(Corresponding to claim 6). In this case, it is preferable to set the angle formed in the vicinity of the collecting portion of each independent branch passage as shallow as possible while minimizing the number of independent branch passages.

Each independent branch passage is configured in one exhaust manifold,
An intermediate member is disposed between the exhaust manifold and the exhaust turbocharger,
In the intermediate member, the downstream portion of each collecting portion and each independent branch passage is formed, and the throttle valve and an actuator for driving the throttle valve are provided,
The downstream portions of the independent branch passages formed in the intermediate member are parallel to each other;
(Corresponding to claim 7). In this case, by using an intermediate member, the exhaust manifold and the turbocharger turbocharger can adopt the same structure as the conventional one while realizing the present invention, which is preferable for practical use. Become. In addition, since the independent passages in the intermediate member are parallel to each other, the suction effect can be more fully exhibited.

  According to the present invention, the exhaust gas can be efficiently supplied to the exhaust turbocharger to improve the engine torque, particularly the engine torque at a low speed.

  In FIG. 1, reference numeral 1 denotes an engine (engine body), which is an in-line four-cylinder spark ignition engine in the embodiment. 2 is a cylinder block, 3 is a cylinder head, and 4 is a piston. The cylinder block 2, the cylinder head 3, and the piston 4 form a combustion chamber 5. An intake port 6 and an exhaust port 7 formed in the cylinder head 3 are opened in the combustion chamber 5, and a spark plug 8 is disposed at a substantially central portion of the combustion chamber 5. The intake port 6 is opened and closed by an intake valve 9, and the exhaust port 7 is opened and closed by an exhaust valve 10.

  The intake port 6 is connected to a surge tank 22 via an independent branch intake passage 21 formed by an intake manifold. One common intake passage 23 is connected to the surge tank 22. In this common intake passage 23, an air cleaner 24, a throttle valve 25, a compressor wheel 26 </ b> A of an exhaust turbocharger 26 and an intercooler 27 are sequentially arranged from the upstream side to the downstream side.

  An exhaust passage 30 described later is connected to the exhaust port 7, and a turbine wheel 26 </ b> B of the exhaust turbocharger 26 is disposed in the exhaust passage 30. The turbine wheel 26B is connected to the compressor wheel 26A by a connecting shaft 26C. When the turbine wheel 26B is driven to rotate by receiving the energy of the exhaust gas, the compressor wheel 26A is driven to rotate, and supercharging is performed. Will be done. When the supercharging pressure exceeds a predetermined value, a waste gate valve (not shown) is opened, and the supercharging pressure is restricted from exceeding a predetermined value.

  In FIG. 2, the four cylinders in series in the engine 1 are denoted by reference numerals C1, C2, C3, and C4. C1 is the first cylinder, C2 is the second cylinder, C3 is the third cylinder, and C4 is the fourth cylinder. In the embodiment, the firing order of the cylinders C1, C2, C3, and C4 (also referred to as the order of the exhaust stroke) is the order of the first cylinder C1, the third cylinder C3, the fourth cylinder C4, and the second cylinder C2. Yes. That is, the second cylinder C2 and the third cylinder C3 in the center are set so that the ignition order (exhaust stroke order) is not adjacent to each other. In each cylinder, the opening timing of the intake valve 9 is set before the intake top dead center, while the closing timing of the exhaust valve 10 is set after the intake top dead center, and the intake valve 9 and the exhaust valve 10 are It is set to have an overlap period in which both are opened. In the following description, when it is not necessary to distinguish between the cylinders, the cylinders may be simply indicated by a symbol C.

  Each cylinder C has two intake ports 6 (two intake valves 9) and two exhaust ports 7 (two exhaust valves 10). In each cylinder C, the intake port 6 is branched into two independently in the vicinity of the two intake valves 9, but opens to one side 1 a side of the engine 1 in a state where the intake ports 6 are assembled in the cylinder head 3. Has been. Similarly, in each cylinder C, the exhaust ports 7 are independent from each other in the vicinity of the two exhaust valves 10, but are opened to the other side surface 1 b side of the engine 1 in a state of being assembled in the cylinder head 3. . The exhaust ports 9 of the second cylinder C2 and the third cylinder C3 are opened to the other side surface 1b of the engine 1 in a state where they are gathered together in the cylinder head 3.

  2 and 3, the exhaust manifold constituting a part of the exhaust passage 30 is indicated by reference numeral 31. The exhaust manifold 31 includes first to third three branch pipes (branch independent passages) 31A, 31B, and 31C that are independent from each other. The first branch pipe 31A at one end is connected to the exhaust port 7 of the first cylinder C1, the second branch pipe 31B at the center is connected to the exhaust ports 7 of the second cylinder C2 and the third cylinder C3, and the second branch pipe 31B at the other end is connected. A 3-branch pipe 31C is connected to the exhaust port 7 of the 4C-th cylinder C4.

  The exhaust turbo supercharger 26 described above is connected to the exhaust manifold 31 via an intermediate member 40. The intermediate member 40 has three independent passages 41A, 41B, and 41C defined by the partition wall 40a at the upstream end thereof. The independent passages 41A, 41B, 41C are parallel to each other. Of course, the independent passage 41A is connected to the branch pipe 31A of the exhaust manifold 31, the independent passage 41B is connected to the branch pipe 31B of the exhaust manifold 31, and the independent passage 41C is connected to the branch pipe 31C of the exhaust manifold 31.

  A collecting portion 42 is formed in the intermediate member 40 at its downstream end. The downstream end of each independent passage 41A, 41B, 41C is gathered with respect to this gathering portion 42. The intermediate member 40 is integrated with the downstream end portion of the exhaust manifold 31 by the upstream flange portion 43. The intermediate member 40 is fixed to the inlet side end of the exhaust turbocharger 26 by the downstream flange portion 44. In the intermediate member 40, the opening area is gradually reduced in the portion from each of the independent passages 41A, 41B, 41C to the collecting portion 42, and the downstream end portion of the collecting portion 42 is finally circular (substantially). Open in a circular shape. The downstream opening end shape of the collecting portion 42 has the same shape and the same size as the inlet shape of the exhaust turbocharger 26.

  Each independent passage 41 </ b> A, 41 </ b> B, 41 </ b> C in the intermediate member 40 is disposed so as to surround the center (substantially center) of the gathering portion 42. That is, the two independent passages 41A and 41C are arranged adjacent to each other so as to be parallel to the cylinder arrangement direction, and the central independent passage 41B is located between the two independent passages 41A and 41C. It is arranged. That is, the independent passages 41A, 41B, and 41C are staggered with respect to each other in the cylinder arrangement direction. Each of the independent passages 41A, 41B, and 41C has a circular cross section, and is configured to have a convex portion 45 in which the outer peripheral edge thereof is enlarged radially outward (center side of the collecting portion 42). . In other words, each independent passage 41A, 41B, 41C is arranged such that its center (substantially center) is positioned on a circular locus centered on the center (substantially center) of the assembly part 42, and the assembly part 42 Are arranged at substantially equal intervals around the center.

  In each of the independent passages 41A, 41B, 41C in the intermediate member 40, a butterfly valve 51A, 51B or 51C as a throttle valve is disposed. Each butterfly valve 51 </ b> A, 51 </ b> B, 51 </ b> C has an arcuate cutout 52 formed at the outer peripheral edge thereof. This notch portion 52 constitutes a gap passage portion. When the butterfly valves 51A to 51C are in the closed state shown in FIGS. 7, 8, and 10, the arc-shaped protrusions of the independent passages 41A, 41B, and 41C are formed. In cooperation with the portion 45, a substantially circular small opening, that is, a diaphragm portion 53 is formed. Further, when the butterfly valves 51A, 51B, 51C in the closed state are rotated by approximately 90 degrees, they are opened as shown in FIG. 11 (fully opened), and the opening areas of the independent passages 41A, 41B, 41C are increased. Increased.

  Each butterfly valve 51A, 51B, 51C is driven to open and close by an actuator 55 such as an electromagnetic motor. That is, the butterfly valve 51B is fixed to a rotation shaft 56 that is rotatably held by the intermediate member 40, and the remaining two butterfly valves 51A and 51C are a common that is rotatably held by the intermediate member 40. The rotating shaft 57 is fixed. One end of each of the rotating shafts 56 and 57 extends to the outside of the intermediate member 40 and is interlocked with each other by gears 58 and 59 (see FIG. 7) fixed to the extending end. The actuator 55 is connected to the rotation shaft 56. Thus, by driving one rotating shaft 56 by the actuator 55, the respective butterfly valves 51A, 51B, 51C are adjusted to have the same opening degree (fully closed or fully opened). In addition, the intermediate opening can be stepwise or continuously variable).

  FIG. 12 shows an example of changing the opening degree of the butterfly valves 51A, 51B, 51C. In FIG. 12, the engine speed and the engine torque (which can be regarded as a boost pressure or an engine load) are set as parameters. First, the X1 line indicated by the solid line indicates the engine torque when the turbocharger 26 is supercharged, and the α point in the figure is the intercept point (when the wastegate valve is opened). The X2 line indicated by a broken line having a higher torque than the X1 line indicates the engine torque when the waste gate valve is not opened. A Y1 line indicated by a one-dot chain line indicates an engine torque corresponding to natural intake without supercharging by the exhaust turbo supercharger 26.

  The Z1 line is a substantially equal horsepower curve passing through the α point, and the Z2 line is a substantially equal horsepower line set slightly higher than the Z1 line. The butterfly valves 51A, 51B, and 51C are fully closed in the low rotation range than the Z1 line, and are fully opened in the high rotation range than the Z2 line. Further, the butterfly valves 51A, 51B, 51C are open between the fully closed and fully open positions in the rotational range between the Z1 line and the Z2 line, and continuously open as the engine speed increases. Is made larger.

  Here, for each cylinder C, the configuration of the branch independent passages leading to the collecting portion 42 is from the exhaust port 7 through the branch pipes 31 </ b> A to 31 </ b> C (internal passages) of the exhaust manifold 31. There are independent passages 41A to 41C. When the total volume of the branch independent passages from the exhaust port 7 to the collecting portion 42 is defined as the total volume, the total volumes of the cylinders C1 to C4 are set to be equal to each other. More specifically, for example, the total volume of the first cylinder C1 is the total volume of the exhaust port 7, the first branch pipe 31A of the exhaust manifold 31, and the independent passage 41A in the intermediate member 40. It becomes. Similarly, the total volume of the fourth cylinder C4 is the total volume of the exhaust port 7, the third branch pipe 31C of the exhaust manifold 31, and the independent passage 41C in the intermediate member 40. On the other hand, the total volume of the second cylinder C2 and the third cylinder C3 in which the exhaust ports 7 are gathered together is the exhaust ports 7 of the quantity cylinders C2 and C3 and the second branch pipe 31B of the exhaust manifold 31. And the total volume of the independent passage 41B in the intermediate member 40.

  The total volume of the branch independent passages for each of the cylinders C1 to C4 is made equal to each other, while the second cylinder C2 and the third cylinder C3 have the exhaust port capacity of two cylinders, so that the second cylinder C2 and the third cylinder The volume of the second branch pipe 31B of the exhaust manifold 31 corresponding to the cylinder C3 is smaller than the volumes of the other branch pipes 31A and 31C. Since the cross-sectional areas of the branch pipes 31A, 31B, and 31C are substantially equal, the length of the second branch pipe 31B is shorter than the lengths of the other branch pipes 31A and 31C (31A and 31A). 31C is set to the same length). And the downstream end part of each branch pipe 31A-31C is extended so that it may cross substantially orthogonally with respect to the upstream flange part 43 of the intermediate member 40, and it merges by the shallow angle as much as possible near the gathering part 42. In addition to this, the independent passages 41A to 41C in the intermediate member 40 are set parallel to each other and set to the shallowest angle.

  In the above configuration, in the low rotation range (lower rotation range than the Z1 line in FIG. 12), the butterfly valves 51A, 51B, and 51C are fully closed, and the open areas of the independent passages 41A to 41C are the same. The aperture is reduced. The aperture area in this aperture state (the aperture area of the aperture portion 53) is an aperture area composed of the convex portion 45 and the cutout portion 52.

  The exhaust gas traveling from the cylinder in the exhaust stroke to the collecting portion 42 through the exhaust port 7 is accelerated in the flow rate by the throttle portion 53 (the convex portion 45 and the notch portion 52), and passes through the collecting portion 42 and is exhausted by the turbocharger. Supplied to the feeder 26. As a result, the exhaust turbocharger 26 is efficiently operated. In particular, exhaust gas (blowdown gas) having a high momentum generated immediately after the exhaust port 7 (exhaust valve 10) is opened is supplied to the exhaust turbocharger 26 in a state where the flow velocity is further increased. The engine torque is improved.

  By increasing the flow rate of the exhaust gas with the throttle, the ejector effect (suction effect) is exerted so that the exhaust gas flowing through one independent intake passage flows (expands) toward another independent passage. As a result, the residual exhaust gas in the other independent passage is also supplied to the exhaust turbocharger 26 by the suction effect, and the engine torque is improved accordingly.

  Furthermore, the scavenging effect of the cylinder in the intake stroke is enhanced by the suction effect, and the charging efficiency is improved by this amount (an improvement of about 10 to 20%), and the engine torque is further improved. The cylinder relationship in which the relationship between the exhaust stroke and the intake stroke is established is as follows. That is, the first cylinder C1 (exhaust stroke), the second cylinder C2 (intake stroke), the second cylinder C2 (exhaust stroke), the fourth cylinder C4 (intake stroke), the third cylinder C3 (exhaust stroke) and the first cylinder C1. (Intake stroke) No. 4 cylinder C4 (exhaust stroke) and No. 3 cylinder C3 (intake stroke).

  The downstream end portions of the branch pipes 31A to 31C in the exhaust manifold 31 are substantially parallel to each other, and the independent passages 41A to 41C configured immediately upstream of the collecting portion 42 are parallel to each other (completely parallel). Thus, the suction effect is sufficiently enhanced. Moreover, since each independent path | route 41A-41C is mutually adjoining, the suction effect in each independent path | route can fully be improved. In particular, since the narrowed portion 53 formed by the convex portion 45 notch portion 52 is positioned near the center of the collective portion 41, it is in a very close relationship, and is extremely preferable for enhancing the suction effect.

  Further, the independent passages 41A to 41C are set so that their relative positional relations are substantially the same, and the total volumes of the independent passages for the cylinders C1 to C4 are equal to each other. The suction effect in the passage can be obtained in the same way.

  When dynamic pressure supercharging is performed, it is desirable to reduce the volume of the passage of exhaust gas as much as possible in order to increase the effect, but exhaust gas from one independent passage flows to another independent passage due to the suction effect. The situation (expanded) is prevented, and the same effect as that of substantially reducing the passage volume can be obtained. By the way, when there is no suction effect, part of the exhaust gas flowing through one independent passage flows to another independent passage, so the passage volume becomes substantially large, and the effect of dynamic pressure supercharging is It will be reduced.

  Here, although leakage of exhaust gas from the gaps around the rotation shafts 56 and 57 may cause a reduction in the suction effect, the rotation shafts 57 that are common rotation shafts are not adjacent to each other in the exhaust stroke 1. Since it is used for the No. cylinder C1 and No. 4 cylinder, the leakage around the rotation shaft 57 is not a problem. It should be noted that the opening change of the butterfly valves 51A, 51B, 51C is relatively insensitive to the suction effect, and a substantially similar suction effect can be obtained within a certain opening range.

  When the engine speed increases and becomes a higher rotation range than the Z2 line in FIG. 12, butterfly valves 51A to 51C are fully opened, and a large amount of exhaust gas can be discharged efficiently. In the rotation range between the Z1 line and the Z2 line in FIG. 12, the opening degree of the butterfly valves 51A to 51C is increased as the engine speed is higher, so that the exhaust gas discharge efficiency and the suction effect are balanced. It will be.

  FIG. 13 shows a second embodiment of the present invention. The same components as those in the above-described embodiment are given the same reference numerals, and redundant description thereof is omitted. In this embodiment, in an in-line four-cylinder engine, a branch independent passage is provided for each cylinder. That is, the exhaust manifold has four branch pipes corresponding to the number of cylinders, and four independent passages 47A to 47D (corresponding to 41A to 41C in the above embodiment) are provided in the intermediate member 40. It is. The independent passages 47A to 47D are arranged so as to surround substantially the center of the collecting portion 42, that is, the independent passages 47A to 47D are arranged at substantially equal intervals in the circumferential direction of the collecting portion 42 (substantially the center thereof). It is arranged.

  The independent passages 47 </ b> A to 47 </ b> D are formed with convex portions 45 that are enlarged toward the center side of the collecting portion 42. In the independent passages 47A to 47D, butterfly valves 49A to 49D (corresponding to the butterfly valves 51A to 51C in the above embodiment) are arranged. The butterfly valves 49 </ b> A to 49 </ b> D are each formed with a cutout portion 52, and the throttle portion 53 is configured by the convex portion 45 and the cutout portion 52 as in the above embodiment.

  The independent passage 47A is for the first cylinder C1, the independent passage 47B is for the second cylinder C2, the independent passage 47C is for the third cylinder C3, and the independent passage 47D is for the first cylinder C4. The common rotation shaft 56 is used for the first cylinder C1 and the fourth cylinder C4 that are not adjacent to each other in the exhaust stroke. Similarly, the common rotation shaft 57 is also the second cylinder C2 that is not adjacent to the exhaust stroke. And for the third cylinder C3. The arrangement of the independent passages 47A to 47D is set so that the connecting line connecting the center of the independent passage 4BA and the center of 47D is orthogonal to the connecting line connecting the center of the independent passage 47A and the center of 47C. Has been. Of course, the rotation shafts 56 and 57 are parallel to each other.

  Although the embodiment has been described above, the present invention is not limited to the embodiment, and can be appropriately changed within the scope described in the scope of claims. For example, the invention includes the following cases. . The same applies to multi-cylinder engines other than four cylinders. For example, in the case of a three-cylinder engine, each branch pipe 31A to 31C may be communicated with only one different cylinder (in the embodiment, the central branch pipe 31B is used for one central cylinder). And it is sufficient). Further, for example, in a six-cylinder engine (in-line six cylinders, V-type six cylinders), one exhaust turbo supercharger 26 is provided for every three cylinders, and a total of two exhaust turbo superchargers 26 are provided. (2 sets of exhaust passage structures are configured for a three-cylinder engine). In an eight-cylinder engine, particularly a V-type eight-cylinder engine, one exhaust turbocharger 26 is provided for each bank (every four cylinders), and a total of two exhaust turbochargers 26 are provided. (2 sets of exhaust passage structures are configured for a four-cylinder engine).

  As the throttle valve, for example, an appropriate type such as a swinging type swinging around one end can be used. The narrowed portion 53 (gap passage portion) may be configured by only the cutout portion 52 without providing the convex portion 45. The intermediate member 40 may be structured at the downstream end of the exhaust manifold 31 without providing the intermediate member 40 separately. The engine is not limited to a spark ignition type engine, but may be a compression ignition type engine typified by a diesel engine, or a reciprocating type rotary engine. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

The system diagram which shows an example of the engine to which this invention was applied. The top view which shows an exhaust path in detail among the engines shown in FIG. FIG. 3 is an exploded perspective view of the exhaust path shown in FIG. 2. The side view of an intermediate member. The left view of FIG. The upper perspective view of an intermediate member. The top view which looked at the intermediate member from the attachment surface side of the exhaust manifold. The top view which looked at the intermediate member from the attachment surface side of the exhaust turbo supercharger. The top view which shows an example of the butterfly valve as a throttle valve. FIG. 8 is a cross-sectional view corresponding to the line AA in FIG. Sectional drawing corresponding to FIG. 10 which shows the time of a butterfly valve being a full open state. The figure which shows the map used for the opening / closing control of a butterfly valve. The principal part top view corresponding to FIG. 7 shows the 2nd Embodiment of this invention.

1: Engine 7: Exhaust port 10: Exhaust valve 26: Exhaust turbo type turbocharger 31: Exhaust manifolds 31A to 31C: Branch pipe (independent branch passage)
40: Intermediate member 40a: Partition walls 41A, 41B, 41C: Independent branch passage 42: Collecting portion 45: Convex portion (for restricting portion formation)
47A-47D: Independent branch passage (FIG. 13)
48: Convex part (in FIG. 13, for forming the narrowed part)
48A-48D: Butterfly valve (FIG. 13)
51A, 51B, 51C: butterfly valve 52: notch (to form a throttle in the gap passage)
53: Aperture part 55: Actuator 56, 57: Rotating shaft

Claims (7)

Three or more independent branch passages connected to different cylinders and independent from each other, a collecting portion where the downstream sides of the independent branch passages are gathered together, and an exhaust turbo-type turbocharger disposed downstream of the gathering portion An exhaust passage structure of a multi-cylinder engine having a feeder,
Each of the independent branch passages is provided with a throttle valve for changing the passage opening area on the upstream side of the collecting portion,
Each throttle valve is formed with a gap passage portion in the direction of another independent branch passage so that the throttle valve becomes a gap when fully closed.
An exhaust passage structure for a multi-cylinder engine. In claim 1,
An exhaust passage structure for a multi-cylinder engine, wherein each of the gap passage portions is formed at a position offset in the direction of the other independent branch passage when the throttle valve is in a closed position. In claim 2,
An exhaust passage structure of a multi-cylinder engine, wherein the plurality of gap passage portions provided in each throttle valve are arranged in a staggered manner. In any one of Claims 1 thru | or 3,
The throttle valve is a butterfly valve;
The gap passage portion is constituted by a notch formed in an outer peripheral edge portion of the butterfly valve.
An exhaust passage structure for a multi-cylinder engine. In any one of Claims 1 thru | or 4,
The downstream end of each of the independent branch passages is connected to the collective portion so as to surround the center of the collective portion,
The gap passage portion is offset and formed at a position toward the center side of the collecting portion.
An exhaust passage structure for a multi-cylinder engine. In claim 5,
The engine is an in-line four-cylinder engine in which the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder are arranged in series with each other, and the exhaust of the second and third cylinders that are the two cylinders in the center The processes are set not to be continuous with each other,
The independent branch passage includes a first independent branch passage that communicates with the exhaust port of the first cylinder, a second independent branch passage that communicates with the exhaust ports of the second and third cylinders, and an exhaust port of the fourth cylinder. The third independent branch passage and the three,
An exhaust passage structure for a multi-cylinder engine. In any one of Claims 1 thru | or 6,
Each independent branch passage is configured in one exhaust manifold,
An intermediate member is disposed between the exhaust manifold and the exhaust turbocharger,
In the intermediate member, the downstream portion of each collecting portion and each independent branch passage is formed, and the throttle valve and an actuator for driving the throttle valve are provided,
The downstream portions of the independent branch passages formed in the intermediate member are parallel to each other;
An exhaust passage structure for a multi-cylinder engine.

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