JPS61244816A - Exhaust manifold in multicylinder engine - Google Patents

Abstract

PURPOSE:To generate a crack only in a small thickness part so as to be provented from reaching a peripheral wall in an exhaust passage, by forming the small thickness part, positioned from the downstream end edge of a partitioning wall toward the upstream in the exhaust passage, in at least one of the both side surfaces of the partitioning wall in which each exhaust passage adjoins. CONSTITUTION:If an engine is operated, an exhaust manifold 10 is heated to a high temperature expanding due to an outflow of high temperature exhaust gas to an exhaust port 5. As a result, the exhaust manifold 10, generating in its peripheral walls 29a, 29d to a cylinder block in the bottom part of the manifold upward direction reaction force F1 in a boss 23 by restricting thermal expansion by a stay 25, generates shearing force by said reaction force F1 and downward directional thermal expansive tensile force F2 in the other peripheral walls 29b, 29c, causing a crack toward a direction A in the drawing to be generated in each partitioning wall 14a, 14d between each exhaust passage 11b, 11d. Here the partitioning wall 14a, forming a recessed part 17 being directed in the upstream direction of the wall in its both side surfaces, enables the crack to be directed in the lengthwise direction of the recessed part 17.

Description

[Detailed Description of the Invention] Ll Two Fish Dish Danshi 1 The present invention relates to an exhaust passage whose upstream end communicates with the exhaust port of each cylinder in a multi-cylinder engine mounted on an automobile, particularly an in-line multi-cylinder engine. This relates to an exhaust manifold for a multi-cylinder engine, which is formed by collecting the downstream ends of the exhaust manifold.

Let's do it.

In the exhaust manifold of a multi-cylinder engine, which is made up of a collection of upstream parts of exhaust passages, the partition wall of the exhaust passage collection part is exposed to high-temperature exhaust on both wall surfaces. Compared to this, temperature changes are rapid and thermal strain is large.Moreover, the downstream edge of the partition wall is thinner to allow the exhaust gas to join and flow with less resistance, and the heat load tends to concentrate on the downstream edge.As a result, Below the partition wall t1M
Cracks tend to form on the edges.

When the cracks formed at the lower edge of the partition wall develop and reach the peripheral wall of the exhaust passage, the exhaust gas leaks outside through the cracks in the peripheral wall without being purified by the catalyst, etc., and from the viewpoint of exhaust gas countermeasures and noise countermeasures, Furthermore, this is not preferable in terms of measures against heat damage to other devices.

Therefore, the present invention relates to an improvement of an exhaust manifold for a multi-cylinder engine that overcomes the above-mentioned difficulties. In an exhaust manifold for a multi-cylinder engine in which the downstream ends of the exhaust passages are assembled together, each of the exhaust passages in the exhaust passage gathering portion is attached to at least one of both sides of a partition wall adjacent to the downstream end of the partition wall. By forming a thin wall portion toward the upstream side of the exhaust passage, if a crack occurs in the partition wall, a crack is generated in the thin wall portion, and the crack is moved upstream of the exhaust passage along the thin wall portion. It is possible to prevent the exhaust gas from reaching the circumferential wall of the exhaust passage due to the loose direction.

Friend JJI An embodiment of the present invention illustrated in the drawings will be described below.

The illustrated four-stroke gasoline engine installed in a passenger car has four cylinders 2 arranged in series inside a cylinder block 1, and each cylinder 2 has an exhaust port 4 provided in a cylinder head 3 at the top thereof. The exhaust port 4 is connected to four exhaust boats 5, each exhaust port 4 is provided with an exhaust valve 6, and the downstream end 7 of the exhaust boat 5 is open to the side surface of the cylinder head 3.

Further, in the lower part of the cylinder head 3 between the downstream ends of the exhaust boat 5, as shown in FIG. The distance between the third downstream end lower b and 7c is the same as the first. The distance between the second downstream end lowers a, 7b and the third. The distance between the fourth downstream end lowers c and 7d is set to be narrower.

Furthermore, the exhaust manifold 10 is formed by casting FCD55S, and the upper part of the exhaust manifold 10 is in contact with the side surface of the cylinder head 3, and the exhaust manifold 10 is
The upper part of the exhaust manifold 10 is integrally attached to the cylinder head 3 by bolts 21 inserted into bolt holes 20 of the upper 7 langes 19 of the exhaust manifold 10.

And the second one. The second. Branch upstream section 12b of third exhaust passages 11b and 11c
, 12C are curved downward in close parallel to each other.

Also, the above-mentioned No. 1. The first... The upper ends of the fourth branch upstream parts 12a and 12d approach each other from positions significantly separated from each other, and
．． It is curved downward in a state closer to the cylinder block 1 than the third branch upstream parts 12b and 12c (see FIG. 5).

Furthermore, these branch upstream parts 12a, 12b, and 12c.

Branch upstream parts 13a, 13b, 13c following 12d,
t3d, the exhaust manifolds 10 are assembled in a substantially rectangular shape as shown in FIG. 6 as they descend downward.
is formed.

To explain this in more detail, see the second section. The third exhaust passage 11b and IIG are mutually separated by a partition 114a, and the third
．． Fourth exhaust passage 11a, lid branch downstream part 13a
, 13d is the second. Third branch downstream section 13b.

13c is partitioned off by partition walls 14b and 14C, and the first branch downstream section 13a and the fourth branch downstream section 13d are separated from each other by a partition wall 14d.

As is clear from FIG. 4, the first branch downstream section 13
a and the second branch downstream portion 13b are the edge 1 of the partition wall 14b.
5b, and the third branch downstream part 13C and the fourth branch downstream part 13d are connected to the edge 15c of the partition wall 14c.
Partition wall 1 located further downstream
The end edges 15a and 15d of the ends 4a and 14d are assembled to form one merging portion 16.

Also second. From the end edge 15a of the partition wall 14a that partitions the third exhaust passages 11b, 11c, a recess 17 that is narrower and longer in width is located at the center in the width direction of the partition wall 14a and extends toward the upstream side of the exhaust passages 11b, 11c. are formed on both sides of the partition wall 14a.

Further, on the upstream side of the partition 114a, a second. A long hole 18 is provided that communicates the third exhaust passages 11b and 11c with each other.

Further, an exhaust pipe (not shown) is integrally connected to the lower 7 langes 22 of the exhaust manifold 10.
An upper part 26 of an abbreviated stay 25 is integrally attached to a boss 23 protruding toward the engine side of the merging portion 16 by bolts 24, and a lower part 27 of the stay 25 is integrally attached to the cylinder block 1 by bolts 28. The inertial force and vibration force acting on the exhaust manifold 10 are firmly fixed and supported by the upper and lower parts of the exhaust manifold 10.

The embodiment shown in the drawings is configured as described above, so that when the engine starts operating, high-temperature exhaust gas generated in the combustion chamber flows out from the plowing port 4 to the exhaust boat 5 and is discharged from the exhaust manifold 10. Passing through passage 11, exhaust manifold 10 is heated to a high temperature and expands.

In this case, when the engine is running, the exhaust manifold 10 is heated and expands in its longitudinal direction.
9d, its thermal expansion is restrained by the stay 25 and an upward reaction force F1 is generated on the boss 23, causing the exhaust manifold 10
a peripheral wall 29b remote from the lower cylinder block 1;
The downward thermal expansion tension F2 and the reaction force F1 at 29c
A shearing force is generated between the partition walls 14a and 14d, and cracks are generated in the direction A in the partition walls 14a and 14d.
There is a tendency to reach b, 29c, but partition wall 1
Since concave portions 17 are formed on both sides of partition wall 14a and are oriented in the upstream direction, cracks that are oriented in the longitudinal direction of partition wall 14a occur in partition wall 14a, and even if the cracks develop, peripheral walls 29b and 29c are formed. without reaching
Cracks can be prevented from occurring in the peripheral walls 29a, 29b, 29c, and 2M, and leakage of exhaust gas can be prevented.

In the present invention, a thin wall portion is formed on at least one of both sides of the partition wall of the exhaust passage gathering portion from the downstream edge of the partition wall toward the upstream side of the exhaust passage. Cracks are generated only inside the exhaust passage, and the cracks are directed upstream of the exhaust passage and do not reach the peripheral wall of the exhaust passage, thereby preventing cracks from occurring on the peripheral wall, and removing unpurified exhaust gas from the peripheral wall. It is possible to prevent the leakage of gas and adequately deal with exhaust gas treatment.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view illustrating an embodiment of an exhaust manifold for a multi-cylinder engine according to the present invention, FIG. 2 is a perspective view thereof, FIG. 3 is a front view thereof, and FIG. 4 is an exhaust passage of the exhaust manifold. 5 is a vertical cross-sectional side view taken along the line v-v in FIG. 4, and FIG. 6 is a cross-sectional horizontal plane taken along the line VT-VI in FIG. 5. It is a diagram. 1...Cylinder block, 2...Cylinder, 3...
- Cylinder head, 4... Exhaust port, 5... Exhaust boat, 6... Exhaust valve, 7... Downstream end opening, 10... Exhaust manifold, 11... Exhaust passage, 12
... Branch upstream part, 13... Branch downstream part, 14...
Partition wall, 15...edge, 16...confluence, 17...
・Concavity, 18...Long hole, 19...Top flange, 2
0... Bolt hole, 21... Bolt, 22... Lower 7 lange, 23... Boss, 24... Bolt, 25...
...stay, 26...upper, 27...lower, 28.
... Bolt, 29... Peripheral wall.

Claims (1)

[Claims] In an exhaust manifold for a multi-cylinder engine, in which the upstream ends of the exhaust passages of the exhaust manifold are communicated with the exhaust ports of each cylinder of the multi-cylinder engine, and the downstream ends of the exhaust passages are collected, each exhaust of the exhaust passage collection part is connected to the exhaust manifold. 1. An exhaust manifold for a multi-cylinder engine, characterized in that a thin wall portion is formed on at least one of both sides of a partition wall adjacent to the passage from the downstream edge of the partition wall toward the upstream side of the exhaust passage.