Exhaust arrangement for internal combustion engine

Details Exhaust arrangement for internal combustion engine Exhaust arrangement for internal combustion engine

2002-12-12

2004-04-20

Denion, Thomas (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

Divider, collector, valve means, or boundary layer device...

C060S299000, C060S323000

Reexamination Certificate

active

06722126

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an exhaust arrangement for a multi-cylinder internal combustion engine of a vehicle.
For the purpose of effectively conducting emission control in a vehicle, there is a demand to provide an exhaust arrangement in which a catalyst is disposed near a combustion chamber of an engine in order to early activate the catalyst at a low temperature upon engine starting operation. In a front-engine front-wheel drive vehicle (FF vehicle) including an engine disposed on the right or left side of an engine room, a catalyst is arranged at substantially a central part of the vehicle and along a fore-and-aft direction of the vehicle. Accordingly, in the FF vehicle, an exhaust pipe connecting the engine and the catalyst has a generally crank shape.
On the other hand, there is known an exhaust manifold which includes a branch portion constituted of a plurality of branch pipes corresponding to engine cylinders. The branch pipes are merged into an exhaust collector on the downstream side. An exhaust pipe connects the exhaust collector with a catalyst disposed downstream of the exhaust collector. The exhaust pipe has a two-part split construction in which two separate exhaust passages extend between the exhaust collector and the catalyst. There is a demand for elongating the two exhaust passages in order to reduce the number of engine revolution required for avoiding the exhaust interference among the engine cylinders.
Japanese Utility Model Application First Publication No. 52-164602 discloses an exhaust arrangement in which two separate exhaust passages are provided.
FIGS. 10 and 11
show such an exhaust arrangement as described in this related art. As shown in
FIG. 10
, exhaust manifold
40
including four branch pipes
41
A-
41
D corresponding to engine cylinders of engine
39
, and exhaust collector
42
connected with downstream portions of branch pipes
41
A-
41
D. Exhaust collector
42
is coupled to first and second exhaust pipes
48
and
49
which are joined together at combined portion
50
. As illustrated in
FIG. 11
, partition wall
43
is disposed within exhaust collector
42
and divides an exhaust path within exhaust collector
42
into first and second exhaust passages
44
and
45
. Branch pipes
41
A and
41
D are communicated with first exhaust passage
44
, and branch pipes
41
B and
41
C are communicated with second exhaust passage
45
. Partition wall
43
has notch
46
in which oxygen sensor
47
is arranged to face an interior of each of first and second exhaust passages
44
and
45
. Oxygen sensor
47
detects an oxygen content in exhaust flowing in each of first and second exhaust passages
44
and
45
. First and second exhaust passages
44
and
45
are communicated with exhaust passages within first and second exhaust pipes
48
and
49
. The exhaust passages within first and second exhaust passages
44
and
45
are merged into a single exhaust passage via combined portion
50
.
SUMMARY OF THE INVENTION
In the related art described above, exhaust collector
42
as well as partition
43
are curved. Exhaust collector
42
has an outside curving portion with a longer curve length and an inside curving portion with a shorter curve length about a center of curvature. Partition wall
43
is similarly curved and has opposed surfaces perpendicular to a direction of a row of the engine cylinders. When viewed in
FIG. 11
, partition wall
43
is perpendicular to a sheet plane of FIG.
11
. Similar to exhaust collector
42
, the opposed surfaces of partition wall
43
respectively form outside and inside curving portions with respect to a center of curvature. Oxygen sensor
47
is disposed in notch
46
formed in partition
43
so as to be exposed an interior of each of first and second exhaust passages
44
and
45
. The exhaust flowing from the engine cylinders into first and second exhaust passages
44
and
45
gathers at the outside curving portion of exhaust collector
42
and the outside curving portion of partition wall
43
. Namely, the exhaust flowing in each of first and second exhaust passages
44
and
45
is concentrated at the respective outside curving portions of exhaust collector
42
and partition wall
43
. Therefore, the exhaust flowing in first exhaust passage
44
cannot be efficiently directed toward oxygen sensor
47
as compared with the exhaust flowing in second exhaust passage
45
. This leads to inaccurate detection of the oxygen content in the exhaust flowing in first and second exhaust passages
44
and
45
.
It would be therefore desirable to provide an exhaust arrangement for an internal combustion engine, in which both emission control and output performance of the engine can be improved.
In one aspect of the present invention, there is provided an exhaust arrangement for a multi-cylinder internal combustion engine of a vehicle, the engine including a row of cylinders, the exhaust arrangement comprising:
an exhaust manifold including a branch portion including a plurality of branch pipes corresponding to the cylinders;
a catalyst disposed downstream of the exhaust manifold;
an exhaust pipe connecting the exhaust manifold to the catalyst, the exhaust pipe defining an exhaust path;
a bend formed in the exhaust pipe, the bend including a plane which divides an interior of the bend into equal halves;
a partition dividing the exhaust path into first and second exhaust passages coextending in a longitudinal direction of the exhaust pipe, the partition extending in the bend in alignment with the plane; and
an oxygen sensor disposed at the bend of the exhaust pipe in alignment with the partition, the oxygen sensor projecting into both of the first and second exhaust passages through a periphery of the partition.
In a further aspect of the present invention, there is provided an exhaust arrangement for a multi-cylinder internal combustion engine of a vehicle, the engine including a row of cylinders, the exhaust arrangement comprising:
an exhaust manifold including a branch portion including a plurality of branch pipes corresponding to the cylinders;
a catalyst disposed downstream of the exhaust manifold;
passage means for defining an exhaust path having a length extending from the exhaust manifold to the catalyst;
bending means for bending the exhaust path to provide the exhaust path with a curve;
partition means for dividing the exhaust path into first and second exhaust passages coextending along the length of the exhaust path, the partition means equalizing the first and second exhaust passages at the curve; and
a sensor projecting into both of the first and second exhaust passages at the curve through the partition means.
In a still further aspect of the present invention, there is provided an exhaust arrangement for a multi-cylinder internal combustion engine of a vehicle, the engine including a row of cylinders, the exhaust arrangement comprising:
an exhaust manifold including a branch portion including a plurality of branch pipes corresponding to the cylinders;
a catalyst disposed downstream of the exhaust manifold;
an exhaust pipe connecting the exhaust manifold to the catalyst, the exhaust pipe defining an exhaust path, the exhaust pipe having a longitudinal axis;
a bend formed in the exhaust pipe, the bend including a plane in which the longitudinal axis of the exhaust pipe lies, the bend including an inner curving periphery and an outer curving periphery extending longer than the inner curving periphery;
a partition dividing the exhaust path into first and second exhaust passages, the partition extending in the bend in alignment with the plane; and
an oxygen sensor disposed at the outer curving periphery of the bend in alignment with the partition, the oxygen sensor projecting into both of the first and second exhaust passages through a periphery of the partition.


REFERENCES:
patent: 4484440 (1984-11-01), Oki et al.
patent: 4745742 (1988-05-01), Nada et al.
patent: 4815274 (1989-03-01), Piatti
patent: 5867985 (1999-02-01), Furuhashi et al.
patent: 6018946 (2000-02-01), Ma

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