Exhaust manifold for four-cylinder engine

• US 20060005535A1
• Filed: 09/12/2005
• Published: 01/12/2006
• Est. Priority Date: 03/08/2002
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Nishizawa, Kimiyoshi, Ashida, Masaaki
• Granted Patent: US 7,520,127 B2
• Time in Patent Office: Days
• US Class Current: 60/302
• CPC Class Codes: F01N 13/08 Other arrangements or adaptations of exhaust conduits pipes, joints or supports therefor in general F16L; collecting or removing exhaust gases of vehicle engines in workshops B08B15/00, on highways E01C1/005
• CPC Class Codes: F01N 13/10 of exhaust manifolds with cooling jacket F01N3/046
• CPC Class Codes: F01N 3/28 Construction of catalytic reactors
• CPC Class Codes: F02B 27/04 in exhaust systems only, e.g. for sucking-off combustion gases
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

In an exhaust manifold of a four-cylinder engine four cylinders of which line up in order of cylinder #1, cylinder # 2, cylinder # 3 and cylinder #4, temperature rise performance of a manifold catalyst improves by shortening a total length of the exhaust manifold while preventing exhaust gas interference between the cylinders. Therefore, an exhaust manifold branch of cylinder # 1 and an exhaust manifold branch of cylinder # 4 in outward sides of the engine that are not fired in succession are made convergent with its convergence angle θ1 being equal to or below 20 degrees to form a first convergent exhaust manifold branch and an exhaust manifold branch of cylinder # 2 and an exhaust manifold branch of cylinder # 3 between the cylinder # 1 and cylinder # 4 that are not fired in succession are made convergent at a minimum distance having a laterally projected shape to form a second convergent exhaust manifold branch. The first and the second convergent exhaust manifold branches are thereafter convergent at a convergence angle θ3 from 0 degrees to 20 degrees.

Claims

1. An engine comprising:

at least four cylinders;

an exhaust manifold mounted to a cylinder head of the engine; and

at least four exhaust manifold branches included in the exhaust manifold and arranged to each cylinder, wherein

two exhaust manifold branches of two cylinders that are not fired in succession are convergent at a first convergence point to form a first convergent exhaust manifold branch;

two exhaust manifold branches of another two cylinders that are not fired in succession are convergent at a second convergence point to form a second convergent exhaust manifold branch,

the exhaust flow path between the cylinder head and the first convergence point is substantially shorter than the exhaust flow path between the cylinder head and the second convergence point, and

the first convergent exhaust manifold branch and the second convergent exhaust manifold branch are thereafter made convergent at a third convergence point just downstream of the second convergence point.

2. An engine as set forth in claim 1, wherein the third convergence point is at an entrance to a catalyst.

3. An engine as set forth in claim 1, wherein the first convergent exhaust manifold branch is straight between the first convergence point and the third convergence point.

4. An engine comprising:

four cylinders;

an exhaust manifold mounted to a cylinder head of the engine; and

exhaust manifold branches included in the exhaust manifold and arranged to each cylinder, wherein

two exhaust manifold branches of two cylinders that are not fired in succession are convergent to form a first convergent exhaust manifold branch, two exhaust manifold branches of another two cylinders that are not fired in succession are convergent to form a second convergent exhaust manifold branch, the first convergent exhaust manifold branch and the second convergent exhaust manifold branch are opened to a collection portion,

two center axes lines of two exhaust manifold branches connected to the first convergent exhaust manifold branch intersect at a first convergent point being located in the first convergent exhaust manifold branch, two center axes lines of two exhaust manifold branches connected to the second convergent exhaust manifold branch intersect at a second convergent point being located in the collection portion, and

the exhaust flow path between the cylinder head and the first convergent point is shorter than the exhaust flow path between the cylinder head and the second convergent point.

5. An engine comprising:

at least four cylinders;

an exhaust manifold mounted to a cylinder head of the engine;

at least four exhaust manifold branches included in the exhaust manifold and arranged to each cylinder;

means for converging two exhaust manifold branches of two cylinders that are not fired in succession at a first convergence point to form a first convergent exhaust manifold branch;

means for converging two exhaust manifold branches of another two cylinders that are not fired in succession at a second convergence point to form a second convergent exhaust manifold branch; and

means for converging the first convergent exhaust manifold branch and the second convergent exhaust manifold branch at a third convergence point just downstream of the second convergence point;

wherein

the exhaust flow path between the cylinder head and the first convergence point is substantially shorter than the exhaust flow path between the cylinder head and the second convergence point.

6. An engine as set forth in claim 5, wherein the third convergence point is at an entrance to a catalyst.

7. An engine as set forth in claim 5, wherein the first convergent exhaust manifold branch is straight between the first convergence point and the third convergence point.