JPH0224897Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is a multi-cylinder engine installed in an automobile, etc., particularly an in-line multi-cylinder engine, in which the upstream end of the exhaust passage of the exhaust manifold communicates with the exhaust port of each cylinder. The present invention also relates to an exhaust manifold for a multi-cylinder engine, which is formed by collecting the downstream ends of the exhaust passages.

Prior Art As shown in FIG. 2, four exhaust passages 11
The upper ends of the branch parts 12a, 12b, 12c, 12d are arranged in series, and the branch parts 12a, 12b, 12d are arranged in series.
Among 12c and 12d, branch parts 12a and 1 on both sides
The lower ends of 2d are curved so as to approach each other and converge together, and the both sides 12a, 12d
The central branch portions 12b, 12c sandwiched by
As shown in the figure, the branch portions 12a, 12b, 12c,
Exhaust manifold 1 for a multi-cylinder engine that is stacked and assembled along a plane perpendicular to the arrangement direction A of 12d.
There is 0.

Problems to be solved by the invention In engines equipped with such exhaust manifolds, detection of exhaust gas properties,
Holes were provided in the exhaust manifold for exhaust system secondary air supply and exhaust recirculation to the intake system.

Only in a specific exhaust passage among the many exhaust passages,
A mounting hole is provided for mounting an O ₂ sensor, which is a type of exhaust gas component concentration detection sensor, and when the O ₂ sensor is mounted in this mounting hole, the O ₂ concentration in the exhaust gas flowing through the exhaust passage can be detected. However, it is not possible to detect the O ₂ concentration in the exhaust gas flowing through other exhaust passages, and therefore it is not possible to accurately determine the average O ₂ concentration in the exhaust gas of the entire engine. .

In addition, if a hole for installing an O ₂ sensor mounting hole is provided in the exhaust passage that has a hole for supplying secondary air to the exhaust system, the O ₂ concentration in the exhaust gas changes due to the supplied secondary air. It is not possible to accurately detect O ₂ concentration in exhaust gas.

Means and Effects for Solving the Problems The present invention relates to an improvement of an exhaust manifold devised to solve the above-mentioned problems, and the upstream end of the exhaust passage communicates with the exhaust port of an in-line four-cylinder engine. However, the No. 2 and No. 3 exhaust passages are adjacent to each other from the upstream side to the downstream side and are independent from each other, and their downstream ends converge, and the downstream ends of the No. 1 and No. 4 exhaust passages converge with each other. In the exhaust manifold for a four-cylinder engine, which is integrally formed so that the No. 2 and No. 3 exhaust passages overlap and gather along a plane perpendicular to the arrangement direction, the No. 2 and No. 3 exhaust passages are integrated. A communication hole elongated in the longitudinal direction of the passage that communicates the upstream parts of the two passages with each other is provided in the partition wall, and the passages No. 1 and No. 4 are located on the downstream side of the communication hole.
One of the exhaust passages No. 2 and one of the exhaust passages No. 2 and 3 adjacent thereto.
By providing the exhaust gas component concentration detection sensor mounting hole so as to face the exhaust passage, secondary air can be supplied to other exhaust passages in which the exhaust gas component concentration detection sensor mounting hole is not provided.

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

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

Further, in the downstream end opening 7 of the exhaust port 5 in the cylinder head 3, as shown in FIG. , 7b and the distance between the third and fourth downstream end openings 7c and 7d.

Further, the exhaust manifold 10 is formed by casting FCD55S, and the upper part of the exhaust manifold 10 is brought into contact with the side surface of the cylinder head 3, and is inserted into the bolt hole 23 of the upper flange 22 of the exhaust manifold 10 and screwed into place. The upper part of the exhaust manifold 10 is integrally attached to the cylinder head 3 through the bolt holes 24 formed therein.

The branched upstream parts 12b and 12c of the second and third exhaust passages 11b and 11c, which communicate with the second and third downstream end openings 7b and 7c, are curved downward so as to be closely parallel to each other. .

Further, the upper ends of the first and fourth branch upstream portions 12a and 12d that communicate with the first and fourth downstream end openings 7a and 7d approach each other from positions significantly separated from each other, and branch upstream part 12b,
It is curved downward in a state closer to the cylinder block 1 than 12c (see FIGS. 1 and 2).

In addition, these branch upstream parts 12a, 12b, 12
The exhaust manifold 10 is formed such that as it descends downward, the exhaust manifolds 10 and 12d converge into a substantially rectangular shape, as shown in FIGS. 5 to 7.

To explain this in more detail, the second and third exhaust passages 11b and 11c are separated from each other by a partition wall 14a, and the first and fourth exhaust passages 11a and 11d are separated from each other by a partition wall 14a.
The branch downstream parts 13a, 13d are separated from the partition walls 14b, 1 with respect to the second and third branch downstream parts 13b, 13c.
4c, and the first branch downstream part 13a and the fourth branch downstream part 13d are
They are separated from each other by a partition wall 14d.

As is clear from FIG. 3, the first branch downstream part 13a and the second branch downstream part 13b are gathered together at the edge 15b of the partition wall 14b, and the third branch downstream part 13c and the second branch downstream part 13b are 4 branch downstream part 13d
are the partition walls 14a and 14d that are gathered at the edge 15c of the partition wall 14c and are further located downstream of the edge 15c.
are gathered together at end edges 15a and 15d to form one merging portion 16.

Also, as illustrated in FIGS. 1 and 4,
A communication hole 18 is formed in the upstream portion of the partition wall 14a that partitions the second and third exhaust passages 11b and 11c, and is narrow on the upstream side and gradually thickens and elongated toward the downstream side.

This shape of the communication hole 18 is effective in causing the exhaust flow to gradually flow into other exhaust passages, thereby minimizing the effects of disturbance of the exhaust flow and exhaust interference. The shape is also advantageous in terms of molding of the communication hole 18 with a core.

Further, as shown in FIGS. 3 and 6, exhaust port downstream end openings 7a, 7b, 7c, 7
The branching of both exhaust passages 11a, 11b at a position where the first and second exhaust passages 11a, 11b begin to overlap and on the downstream side of the communication hole 18 when viewed from the direction perpendicular to the arrangement plane of d (see Fig. 3). Part peripheral wall 17a,
17b, an O ₂ sensor mounting hole 19 is formed in a partition wall 14b that partitions both exhaust passages 11a and 11b.

Furthermore, the branch peripheral wall 17d of the fourth exhaust passage 11d has an exhaust gas take-off hole 20 for exhaust gas recirculation and a secondary air introduction hole 2 for introducing secondary air.
1 is formed.

Moreover, the lower flange 25 of the exhaust manifold 10
An exhaust pipe (not shown) is integrally connected to the exhaust manifold 10, and an upper part 29 of a substantially L-shaped stay 28 is integrally attached to a boss 26 protruding toward the engine side of the merging portion 16 of the exhaust manifold 10 with a bolt 27. , the lower part 30 of the stay 28 is integrally attached to the cylinder block 1 by a bolt 31,
The inertia force and vibration force acting on the exhaust manifold 10 are firmly fixed and supported at the upper and lower parts thereof.

The illustrated embodiment 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 exhaust port 4 to the exhaust port 5 and passes through the exhaust passage 11 of the exhaust manifold 10.
communicate.

In this case, the second and third exhaust passages 11b, 11
c is partitioned by a partition wall 14a, but since a communication hole 18 is formed in the partition wall 14a,
A part of the exhaust gas flowing through the second exhaust passage 11c can flow into the second exhaust passage 11b, and
The detection part of the O ₂ sensor (not shown) fitted in the O ₂ sensor mounting hole 19 is exposed to the exhaust gas flowing through the first and second exhaust passages 11a and 11b. The O ₂ concentration in the exhaust gas generated in the combustion chamber of the third cylinder can be detected on average.

Moreover, since the exhaust gas take-off hole 20 and the secondary air introduction hole 21 are provided in the fourth exhaust passage 11d which does not communicate with the O ₂ sensor mounting hole 19 on the upstream side thereof, the exhaust gas take-off hole 20 Since the influence of the exhaust gas extracted from the cylinder and the secondary air introduced from the secondary air introduction hole 21 does not affect the O ₂ sensor mounting hole 19, the exhaust gas generated in the combustion chamber of the cylinder The O ₂ concentration can be detected accurately.

Effects of the invention As described above, in the exhaust manifold of the present invention, the No. 4 or No. 1 exhaust passage that supplies secondary air is separated from the No. 1 or No. 4 exhaust passage and the No. 2 exhaust passage that supplies secondary air.
Since the properties of the exhaust gas flowing through the exhaust passages No. 3 and 3 can be detected, the average O ₂ concentration of the exhaust gas discharged from the engine can be accurately determined without being affected by O ₂ concentration changes due to the supplied secondary air. can be measured.

[Brief explanation of the drawing]

FIG. 1 is a vertical side view illustrating an embodiment of the exhaust manifold for a multi-cylinder engine according to the present invention;
The figure is a perspective view, the third figure is a front view showing the exhaust passage and boss of the exhaust manifold with dotted lines, and the fourth figure is a front view showing the exhaust passage and boss of the exhaust manifold with dotted lines.
The figure is a longitudinal cross-sectional side view taken along the - line of Fig. 3, Figs. 5 and 6 are cross-sectional views taken along the - line and - line of Fig. 3, and Fig. 7 is a cross-sectional view taken along the - line of Fig. 4. FIG. 1...Cylinder block, 2...Cylinder, 3
... Cylinder head, 4 ... Exhaust port, 5 ... Exhaust port, 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... End edge, 16... Merging part, 17...
Branching part peripheral wall, 18... Communication hole, 19... O ₂ sensor mounting hole, 20... Exhaust gas extraction hole, 21...
Secondary air introduction hole, 22... Upper flange, 23...
...Bolt hole, 24...Bolt, 25...Lower flange, 26...Boss, 27...Bolt, 28...
...stay, 29...upper, 30...lower, 31...
…bolt.

Claims (1)

[Scope of utility model registration request] The upstream end of the exhaust passage communicates with the exhaust port of the in-line four-cylinder engine, and the No. 2 and No. 3 exhaust passages are adjacent and independent from the upstream side to the downstream side, and their downstream ends converge. , a 4-cylinder engine in which the downstream ends of the No. 4 exhaust passages are integrally formed so that they converge and overlap along a plane perpendicular to the arrangement direction of the No. 2 and No. 3 exhaust passages. In the exhaust manifold, the partition wall that partitions the No. 2 and No. 3 exhaust passages is provided with an elongated communication hole in the longitudinal direction of the passage that communicates the upstream portions of the two passages with each other, and the communication hole is located downstream of the communication hole. So, number 1 above,
The exhaust gas component concentration detection sensor mounting hole is provided so as to face two exhaust passages: one of the No. 4 exhaust passages and one of the No. 2 and No. 3 exhaust passages adjacent thereto. Exhaust manifold for a multi-cylinder engine.