JPH09296733A - Exhaust system for vehicle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust system capable of satisfying a desired engine performance, reducing an overhang level in an exhaust gas turbocharger, reducing an associated engine in its size, and having advantages in mounting an exhaust gas turbocharger on a vehicle. SOLUTION: Branch pipes 36 to 42 of an exhaust manifold 34 which are attached on a cylinder head 10 of a multiple cylinder engine 6 are provided at their one ends with a head-mounting flange 54, and are formed halfway in parallel to the flange face of the head-mounting flange 54. The branch exhaust passages, one ends of which are respectively to be connected to exhaust ports 16 to 22 of cylinders #1 to #4 of the engine the exhaust timings of which do not overlap, are at the other ends made confluent with each other to be connected to united exhaust passages at that end side. The branch pipes 36 to 42 are joined to unite the united exhaust passages at the other end side, and are then respectively joined to the first to fourth exhaust ports 24 to 30 in the cylinder head 10 at their middle portions with respect to the parallel direction of the exhaust ports. A connection-mounting flange 64 is provided for uniting the united exhaust passages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for a vehicle engine, and more particularly, it is possible to eliminate exhaust interference, which is advantageous in terms of engine performance, and to mount an exhaust supercharger close to the engine. A vehicle that can meet the requirements of engine performance, can reduce the amount of overhang of the exhaust supercharger, can make the engine compact, and can be advantageous in mounting the exhaust supercharger on the vehicle. Regarding an exhaust system of an engine.

[0002]

2. Description of the Related Art A vehicle engine (hereinafter referred to as an "engine") mounted on a vehicle or the like is provided with an exhaust device for discharging exhaust gas. As an exhaust device, there is one shown in FIGS.

In FIG. 17, the exhaust system 102 is provided with an exhaust manifold 104 attached to a cylinder head of an engine having four cylinders mounted on a vehicle (not shown). The exhaust manifold 104 has a short first portion.
~ Fourth branch pipes 106 to 112 are provided.

The first to fourth branch pipes 106 to 112 are provided with first to fourth branch exhaust passages 114 to 120 communicating with the first to fourth exhaust ports (not shown) of the cylinder head, and each one side. A head mounting flange 122 that is mounted on the cylinder head is provided at the end.

The short first to fourth branch pipes 106 to 112
The other end side thereof is joined to a merging pipe 124 substantially parallel to the cylinder head, and the first to fourth branch exhaust passages 114 to 120 are provided so as to join the merging exhaust passage 126. Confluence pipe 124
Connecting flanges 128 are provided at the other ends of the first to fourth exhaust ports in the parallel direction.

In FIGS. 18 and 19, 202 is an engine, 204 is a cylinder block, 206 is a cylinder head, 208 is a head cover, 210 is an oil pan, and 212 is an exhaust device. The exhaust device 212 is an engine 202 having four cylinders mounted on a vehicle (not shown).
Exhaust manifold 2 attached to the cylinder head 206 of
14 are provided. The exhaust manifold 214 is provided with first to fourth branch pipes 216 to 222.

The first to fourth branch pipes 216 to 222 are first to fourth exhaust ports (not shown) of the cylinder head 206.
First to fourth branch exhaust passages 224 to 230 communicating with the head mounting flange 234 to be mounted on the head side mounting surface 232 of the cylinder head 206.

The other ends of the first and fourth branch pipes 216 and 222 are respectively joined to the one ends of the first joining pipe 236 to join the first and fourth branch exhaust passages 224 and 230 into the first joining pipe. It is provided so as to join the exhaust passage 238. The other ends of the second and third branch pipes 218 and 220 are respectively joined to the one ends of the second merging pipe 240 to form second and third branch exhaust passages 226 and 22.
8 are provided so as to merge with the second merged exhaust passage 242.

The other ends of the first and second merging pipes 236 and 240 are joined to the one ends of the third merging pipe 244, respectively, to join the first and second merging exhaust passages 238 and 242 to the third merging. It is provided so as to join the exhaust passage 246. At the other end of the third merging pipe 244, a connecting mounting flange 248 is provided.

Further, in FIG. 20, 302 is a vehicle,
304 is an engine room, 306 is an engine, and 308 is an exhaust device. The exhaust device 308 is provided with an exhaust manifold 312 attached to a cylinder head 310 of an engine 306 having four cylinders # 1 to # 4 mounted in an engine room 304 of a vehicle 302. The exhaust manifold 312 is provided with first to fourth branch pipes 314 to 320.

The first to fourth branch pipes 314 to 320 are formed to be short and communicate with the first to fourth exhaust ports 322 to 328 of the cylinder head 310.
30 to 336. The first to fourth branch pipes 31
A head mounting flange 340 that is mounted on the head side mounting surface 338 of the cylinder head 310 is provided at one end of each of 4 to 320.

The short first to fourth branch pipes 314 to 320
The other end side of each of the first to fourth branch exhaust passages 33 is joined to the first merging pipe 342 which is substantially parallel to the cylinder head 310.
0 to 336 are provided so as to merge with a first merged exhaust passage 344 substantially parallel to the cylinder head 310. First merging pipe 34
In the middle of 2, the one end of the second merging pipe 346, which is formed to be short, is joined, and the second merging exhaust passage 348 is merged in the middle of the first merging exhaust passage 344. Second merging pipe 34
At the other end of 6, an attachment flange 350 for communication is provided, and an exhaust supercharger 352 is attached.

Exhaust systems for such vehicle engines are disclosed in Japanese Utility Model Laid-Open No. 58-191339 and Japanese Utility Model Laid-Open No. 1-15.
7225 and JP-A-63-289216.

In the exhaust system disclosed in Japanese Utility Model Laid-Open No. 58-191339, the cylinders that do not interfere with each other are divided into two groups, and a resonance pipe is connected to the exhaust manifold of each of these groups, and the inlet of the exhaust turbine is connected. The two resonance pipes are merged with each other, and the output of the exhaust turbine is transmitted to the engine output shaft via the transmission gear.

The exhaust system disclosed in Japanese Utility Model Laid-Open No. 1-157225 divides a cylinder of a multi-cylinder engine into a first cylinder group and a second cylinder group, and exhausts each cylinder in each cylinder group. Make sure that the valve opening times do not substantially overlap each other,
In the first cylinder group, the exhaust ports of the cylinders adjacent to each other are made common, and the exhaust ports are merged by the first exhaust manifold, and the exhaust ports of the cylinders adjacent to each other in the second cylinder group are connected to each other. In addition to being common, each exhaust port is joined by a second exhaust manifold.

The exhaust system disclosed in Japanese Patent Laid-Open No. 63-289216 has an independent exhaust passage connected to the exhaust port of each cylinder in the exhaust passage upstream of the exhaust turbine of the exhaust turbocharger. In an exhaust system for a multi-cylinder engine with an exhaust turbocharger, a communication passage that connects the independent exhaust passages of separate cylinders to each other in the vicinity of the exhaust port is provided only for some of all cylinders of the engine. The cylinders are provided and some of the cylinders are other than the cylinder closest to the exhaust turbine.

[0017]

By the way, as shown in FIG.
The exhaust device 212 shown in FIG. 19 is the exhaust manifold 21.
The first and fourth branch pipes 216 and 222 of the fourth connecting pipe 23
6 and the second and third branch pipes 218 and 220
Is joined to the second joining pipe 240, and the first and second joining pipes 236
・ By joining 240 to the third confluence pipe 244, 4
In an engine 202 having a cylinder, it is known as an ideal shape in which exhaust interference can be avoided, an exhaust passage length can be secured, and a pulsating effect can be utilized.

Also, when an exhaust supercharger (not shown) is attached to the engine 202, as shown in FIGS.
The shape of the exhaust manifold 214 of the exhaust device 212 shown in FIG.

However, the exhaust device 2 shown in FIGS.
In FIG. 12, the exhaust supercharger is connected to the exhaust manifold 214 at the outlet side of the third confluent pipe 244 with a connecting mounting flange 248.
It is attached to. This is because the space of the engine room is restricted and the mounting position of the exhaust supercharger is limited.

Therefore, in the exhaust device 212 shown in FIGS. 18 and 19, the distance from the engine 202 to the exhaust supercharger becomes long, and the exhaust supercharger is mounted away from the engine 202. There is a disadvantage that the overhang amount of the supercharger becomes large.

Therefore, in the exhaust system 308 shown in FIG. 20, the short first to fourth branch pipes 314 to 320 of the exhaust manifold 312 are arranged substantially parallel to the cylinder head 210.
By joining the joining pipe 342, joining the short second joining pipe 346 in the middle of the first joining pipe 342, and attaching the exhaust supercharger 352 to the connecting attachment flange 350 of the second joining pipe 346, The distance to the exhaust supercharger 352 is shortened, and the exhaust supercharger 352 is mounted close to the engine 306.

However, the exhaust device 308 shown in FIG.
The short first to fourth branch pipes 314 of the exhaust manifold 312
320 is a first converging pipe 3 that is substantially parallel to the cylinder head 310.
Since it is joined to 42, it causes exhaust interference, cannot secure the exhaust passage length, and cannot use the pulsation effect. Similarly, in the exhaust device 102 shown in FIG. 17, too, the short first to fourth branch pipes 106 to 112 are joined to the confluent pipe 124 substantially parallel to the cylinder head, which causes exhaust interference and the exhaust passage length. Cannot be ensured and the pulsating effect cannot be used.

Therefore, in a limited space, exhaust interference can be eliminated, the exhaust passage length can be secured, which can be advantageous in terms of performance, and the distance from the engine to the exhaust supercharger can be shortened. Thus, there is a desire for a time limit for an exhaust system that allows the exhaust supercharger to be mounted close to the engine.

[0024]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention provides an exhaust manifold attached to a cylinder head of an engine having multiple cylinders mounted on a vehicle. Each branch pipe having a branch exhaust passage communicating with each exhaust port of the cylinder head is provided, and a head mounting flange to be attached to the cylinder head is provided at one end of each branch pipe. Is formed so as to be parallel to the head flange surface of the head mounting flange, and the other end side of each branch exhaust passage that communicates one end side with each exhaust port of the cylinder where exhaust timing of the engine does not overlap The branch pipes so as to join each other to communicate with one end side of each of the combined exhaust passages and to join the other end side of each of the combined exhaust passages. It is provided by joining, and the other end side of each of these branch pipes is joined at an intermediate position in the exhaust port parallel direction of the cylinder head to provide a connecting mounting flange. It is characterized in that the ends are joined together.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The exhaust system for a vehicle engine according to the present invention merges the other end side of each branch exhaust passage, which communicates one end side with each exhaust port of a cylinder whose engine exhaust timing does not overlap, respectively. By connecting the branch pipes of the exhaust manifold to communicate with one end side of each combined exhaust passage and join the other end side of each combined exhaust passage, the exhaust timings from the cylinders that do not overlap each other The exhaust flow can be collected sequentially.

In the exhaust system for a vehicle engine according to the present invention, each branch pipe of the exhaust manifold is formed so as to be parallel to the head flange surface of the head mounting flange so that each branch pipe is provided. The length of the exhaust passage can be increased, and the exhaust passage length can be secured.

Further, in the exhaust system for a vehicle engine according to the present invention, the branch pipes of the exhaust manifold are formed so as to be parallel to the head flange surface of the head mounting flange, and the other side of each branch pipe is provided. By connecting the ends at the intermediate position in the direction parallel to the exhaust ports of the cylinder head and providing the connecting mounting flange, the distance from the engine to the connecting mounting flange can be shortened.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 16 show an embodiment of the present invention. 1 and 2, 2 is a vehicle, 4 is an engine room, 6 is a vehicle engine (hereinafter referred to as "engine"), 8 is a cylinder block, 10 is a cylinder head,
Reference numeral 12 is a head cover, and 14 is an oil pan.

A multi-cylinder engine 6 is mounted in the engine room 4 of the vehicle 2. Engine 6 of this embodiment
Has four cylinders of first to fourth cylinders # 1 to # 4.
The engine 6 has the centers of the first to fourth cylinders # 1 to # 4 oriented vertically in the engine room 4 and is mounted in parallel in the horizontal direction (the width direction of the vehicle 2).

The cylinder head 10 has first to fourth parts.
First to fourth intake ports 16 that communicate with the cylinders # 1 to # 4
22 and first to fourth exhaust ports 24 to 30 are provided. These first to fourth intake ports 16 to 22 and first to fourth
The fourth exhaust ports 24 to 30 are provided in the cylinder head 10 in parallel in the horizontal direction.

The engine 6 is provided with an exhaust device 32. The exhaust device 32 is provided with an exhaust manifold 34 attached to the cylinder head 10. The exhaust manifold 34 includes the first to fourth branch pipes 3 as shown in FIGS.
6 to 42 are provided.

The first to fourth branch pipes 36 to 42 have first to fourth branch exhaust passages 44 to 50 communicating with the first to fourth exhaust ports 24 to 30 of the cylinder head 10, respectively. Each of the first to fourth branch pipes 36 to 42 has a head mounting flange 54 mounted on the head side mounting surface 52 of the cylinder head 10 at one end thereof. A mounting hole 56 is provided in the head mounting flange 54.

The exhaust manifold 34 is arranged so that the pipe center A is parallel to the head flange surface 58 of the head mounting flange 54, as shown in FIG. 3, in the middle of the first to fourth branch pipes 36 to 42. It is formed and provided. Further, in the exhaust manifold 34, in the middle of the first to fourth branch pipes 36 to 42, as shown in FIGS.
Are formed so as to be parallel to each other in the vertical direction.

The exhaust manifold 34 includes the first and fourth cylinders # which are arranged so that the exhaust timings of the engine 6 do not overlap.
One end side of the first merged exhaust passage 60 by merging the other end sides of the first and fourth branch exhaust passages 44 and 50 communicating one end side with the first and fourth exhaust ports 24 and 30 of 1 and # 4, respectively. The other end sides of the first and fourth branch pipes 36 and 42 are joined to each other so as to communicate with each other.

Further, the exhaust manifold 34 is connected to the engine 6
Of the second / third branch exhaust passages 46/48 whose one ends communicate with the second / third exhaust ports 26/28 of the second / third cylinders # 2 / # 3, respectively, where the exhaust timings of the two do not overlap. The other ends of the second and third branch pipes 38, 40 are joined together so that the two sides merge and communicate with one end of the second combined exhaust passage 62.

Further, the exhaust manifold 34 joins the other ends of the first to fourth branch pipes 36 to 62 so as to join the other ends of the first and second combined exhaust passages 60 and 62. It is provided.

As a result, the exhaust manifold 34 has its one end connected to the first and fourth exhaust ports 24 and 30 of the first and fourth cylinders # 1 and # 4 where the exhaust timings of the engine 6 do not overlap. 1 · 4th branch exhaust passage 44.5
The second and third exhaust ports of the second and third cylinders # 2 and # 3, in which the other end side of 0 is joined to communicate with one end side of the first combined exhaust passage 60 and the exhaust timings of the engine 6 do not overlap. The second merged exhaust passage 6 is formed by merging the other end sides of the second and third branched exhaust passages 46 and 48, which communicate one end side with the 26 and 28 respectively.
2 is connected to one end side of the first and second combined exhaust passages 6
First to fourth branch pipes 3 so that the other ends of 0.62 are joined.
6 to 42 are joined and provided.

In the exhaust manifold 34, the other ends of the first to fourth branch pipes 36 to 42 are joined at intermediate positions in the parallel direction of the first to fourth exhaust ports 24 to 30 of the cylinder head 10. A mounting flange 64 for communication is provided. A mounting hole 66 is provided in the connecting mounting flange 64.

As shown in FIG. 8, the exhaust manifold 34 is provided on the connecting flange surface 68 of the connecting mounting flange 64 by merging the other ends of the first and second merging exhaust passages 60 and 62. .

The exhaust manifold 34 is shown in FIG.
As shown in FIG. 2, the exhaust supercharger 70 is mounted on the connecting flange surface 68 of the connecting mounting flange 64 located in the middle of the first to fourth exhaust ports 24 to 30 of the cylinder head 10 in the parallel direction. Are provided. The first and second merged exhaust passages 60, 62 that merge at the connecting flange surface 68 of the connecting mounting flange 64 are communicated with an inlet port (not shown) of the exhaust supercharger 70.

As described above, the exhaust device 32 is shown in FIGS.
As shown in FIG. 13, the first and fourth exhaust ports 2 of the first and fourth cylinders # 1 and # 4 in which the exhaust timings do not overlap.
The other end of the first and fourth branch exhaust passages 44 and 50, which communicate with one end to 4 and 30, respectively, join together to form the first combined exhaust passage 60.
Second and third exhaust ports 2 of the second and third cylinders # 2 and # 3 that communicate with one end of the cylinders and do not overlap in exhaust timing.
The second combined exhaust passage 62 is formed by merging the other end sides of the second and third branched exhaust passages 46 and 48, which communicate one end side with the 6 and 28 respectively.
Of the first and second combined exhaust passages 60 communicating with one end side of the
By connecting the first to fourth branch pipes 36 to 42 of the exhaust manifold 34 so as to join the other end side of 62, the flow of exhaust gas from the first to fourth exhaust ports 24 to 30 is 4 Books → 2 → 1 can be collected in order.

That is, the first to fourth branch exhaust passages 44 to 50 of the exhaust manifold 34 are as shown in FIGS.
The first and fourth branch exhaust passages 44 and 50 and the second and third branch exhaust passages 46 whose exhaust timings do not overlap each other
The 48 are provided so as to join the first and second combined exhaust passages 60 and 62, respectively, and the first and second combined exhaust passages 60 and 62 are joined to communicate with the exhaust supercharger 70. , Exhaust timing does not overlap 1st ~
First to fourth exhaust ports 24 to 30 of the fourth cylinders # 1 to # 4
It is possible to sequentially collect the exhaust flow from 4 to 2 to 1 and supply it to the exhaust supercharger 70.

Therefore, the exhaust device 32 collects the flow of exhaust gas from the first to fourth exhaust ports 24 to 30 in order of 4 → 2 → 1 to obtain the exhaust manifold 34, and thus the exhaust manifold 34 is exhausted. Interference can be eliminated.

As shown in FIG. 3, the exhaust device 32 is arranged such that the midpoints of the first to fourth branch pipes 36 to 42 of the exhaust manifold 36 are parallel to the head flange surface 58 of the head mounting flange 54. It is formed on and is provided in FIG.
As shown in FIG. 7, the first to fourth branch exhaust passages 44 to 50 can be made longer by providing them so as to be arranged in parallel in the vertical direction of the engine 6, respectively. The length can be secured.

Therefore, the exhaust device 32 can secure the exhaust passage length, which is advantageous in the performance of the engine 6.

Further, the exhaust device 32 is provided such that the midpoints of the first to fourth branch pipes 36 to 42 of the exhaust manifold 34 are formed in parallel with the head flange surface 58 of the head mounting flange 54, respectively. In addition, the first to fourth branch pipes 36 to 42 are formed in parallel with each other in the vertical direction of the engine 6, and the other ends of the first to fourth branch pipes 36 to 42 are arranged in the parallel direction of the first to fourth exhaust ports 24 to 30 of the cylinder head 10. The exhaust manifold 34 can be formed compactly by providing the connecting mounting flange 64 by joining in the middle of the engine 6
Can be mounted in close proximity to, and the distance from the engine 6 to the connecting mounting flange 64 to which the exhaust supercharger 70 is mounted can be shortened.

Therefore, in the exhaust device 32, the exhaust supercharger 70 can be mounted close to the engine 6.

As described above, the exhaust system 32 can eliminate the exhaust interference and can be advantageous in the performance of the engine 6.
The exhaust supercharger 70 can be mounted in close proximity to the engine 6, whereby the requirements for engine performance can be satisfied, the amount of overhang of the exhaust supercharger 70 can be reduced, and the engine 6 can be made compact. As a result, the exhaust supercharger 70 can be advantageously mounted in the engine room 4 of the vehicle 2.

In this embodiment, as shown in FIG. 3, the center B of the connecting mounting flange 64 to which the exhaust supercharger 70 is mounted is set to the center C of the first to fourth exhaust ports 24 to 30 in the parallel direction. Although it is provided so as to be offset from the fourth exhaust port 30 side, the center B of the connecting mounting flange 64 may be provided so as to coincide with the center C in the first to fourth exhaust port parallel directions. In this way, the mounting flange for communication 6
By making the center C of 4 coincide with the center C of the first to fourth exhaust ports, the exhaust manifold 34 can be made even more compact, and the exhaust supercharger 70 is provided with the first to fourth exhaust ports.
The exhaust gases of the cylinders # 1 to # 4 can be made to flow in substantially evenly, which can contribute to the improvement of the supercharging characteristics.

[0050]

As described above, in the exhaust system for a vehicle engine of the present invention, exhaust interference can be eliminated by sequentially collecting the exhaust flows of the cylinders whose exhaust timings do not overlap, and each branch exhaust passage can be eliminated. Can be made longer and the exhaust passage length can be secured, which can be advantageous in terms of performance, and the distance from the engine to the connecting mounting flange can be shortened.

Therefore, according to the present invention, the exhaust system of the vehicle engine can eliminate the exhaust interference and can be advantageous in terms of engine performance, and the exhaust supercharger can be mounted close to the engine. The engine performance requirements can be satisfied, the overhang amount of the exhaust supercharger can be reduced, the engine can be made compact, and the exhaust supercharger can be advantageously mounted on a vehicle.

[Brief description of drawings]

FIG. 1 is a plan view of an engine room of a vehicle showing an embodiment of an exhaust system for a vehicle engine according to the present invention.

FIG. 2 is a perspective view of an exhaust system of a vehicle engine.

FIG. 3 is a plan view of an exhaust manifold.

FIG. 4 is a front view of an exhaust manifold.

FIG. 5 is a rear view of the exhaust manifold.

FIG. 6 is a left side view of the exhaust manifold.

FIG. 7 is a right side view of the exhaust manifold.

FIG. 8 is a front view of a connecting mounting flange.

9 is a sectional view taken along line IX of FIG.

10 is a cross-sectional view taken along the line X of FIG.

11 is a sectional view taken along line XI of FIG.

12 is a sectional view taken along line XII of FIG.

13 is a sectional view taken along line XIII of FIG.

FIG. 14 shows a change in passage shape of a second combined exhaust passage,
(A) is a cross-sectional view of the XIV line portion of FIG. 3, (B) is a cross-sectional view of the XV line portion of FIG. 3, (C) is a cross-sectional view of the XVI line portion of FIG.

15A and 15B show changes in the shape of the first combined exhaust passage on the side of the first branch exhaust passage, FIG. 15A being a sectional view taken along the line XIV in FIG. 3, and FIG. 15B being a sectional view taken along the line XV in FIG. FIG. 3C is a sectional view taken along the line XVI of FIG.

16A and 16B show changes in the shape of the first combined exhaust passage on the side of the fourth branch exhaust passage, FIG. 16A being a cross-sectional view taken along the line XVI in FIG. 3, and FIG. 16B being a cross-sectional view taken along the line XVII in FIG. Figure, (C)
FIG. 4 is a sectional view taken along the line XVIII in FIG.

FIG. 17 is a plan view of an exhaust manifold showing a conventional example of an exhaust device.

FIG. 18 is a front view of an exhaust manifold showing another conventional example of the exhaust device.

19 is a side view of the engine with the exhaust manifold of FIG. 18 attached.

FIG. 20 is a plan view of an engine room of a vehicle showing still another conventional example of the exhaust device.

[Explanation of symbols]

 2 Vehicle 6 Engine 8 Cylinder Block 10 Cylinder Head # 1 to # 4 1st to 4th Cylinder 16 to 22 1st to 4th Intake Port 24 to 30 1st to 4th Exhaust Port 32 Exhaust Device 34 Exhaust Manifold 36 to 42 First to fourth branch pipes 44 to 50 First to fourth branch exhaust passages 52 Head side mounting surface 54 Head mounting flange 58 Head flange surface 60 First merging exhaust passage 62 Second merging exhaust passage 64 Connecting mounting flange 68 Connecting flange surface 70 Exhaust turbocharger

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F02B 37/02 F02B 37/00 301H

Claims (3)

[Claims] 1. A branch pipe provided with an exhaust manifold attached to a cylinder head of an engine having multiple cylinders mounted on a vehicle, the exhaust manifold having branch exhaust passages communicating with respective exhaust ports of the cylinder head. A head mounting flange to be mounted on the cylinder head is provided at one end of each branch pipe, and the middle of each branch pipe is formed to be parallel to the head flange surface of the head mounting flange. The other end of each branch exhaust passage, one end of which communicates with each exhaust port of the cylinder where the exhaust timings of the engine do not overlap, is joined to communicate with one end of each of the combined exhaust passages. The branch pipes are joined to each other so that the other ends of the exhaust passages merge, and the other ends of the branch pipes are connected to the exhausts of the cylinder head. An exhaust system for a vehicle engine, characterized in that a connecting mounting flange is provided so as to be joined at an intermediate position in the port parallel direction, and the other end side of each of the merging exhaust passages is joined to the connecting mounting flange. 2. The exhaust system for a vehicle engine according to claim 1, wherein the exhaust manifold is formed such that the midpoints of the respective branch pipes are arranged in parallel in the vertical direction of the engine. 3. The exhaust manifold according to claim 1, wherein an exhaust turbocharger is attached to the connecting attachment flange provided at an intermediate position in the exhaust port parallel direction of the cylinder head. Vehicle engine exhaust system.