EXHAUST MANIFOLD FOR ENGINE

BACKGROUND OF THE INVENTION
(1) Field of the Invention

[0001]
The present invention relates to an exhaust manifold for an engine, and specifically, to an exhaust manifold for an engine with which deterioration of sealability between a cylinder head and an exhaust inlet flange can be suppressed.

(2) Description of Related Art
[0002]
A conventional exhaust manifold for an engine includes an exhaust merging portion arranged at the center of the exhaust manifold and a plurality of branch pipes arranged on the both ends of the exhaust merging portion, in which the branch pipes are each provided with an exhaust inlet flange to be attached to a cylinder head (for example, see JP 2001-207841 A).

However, this conventional technique involves problems, since an opposite-head side built-up portion is provided to each of the exhaust merging portion and the branch pipes in forming a rib-like opposite-head side built-up portion at and along the longitudinal direction of an opposite-head side face, out of a head side face facing the cylinder head and the opposite-head side face opposing thereto.

[0003] «Problem»
Sealability between the cylinder head and the exhaust inlet flange of the exhaust manifold tends to deteriorate.

Since the opposite-head side built-up portion is formed at each of the exhaust merging portion and the branch pipes, when the driving engine is stopped, sealability between the cylinder head and the exhaust inlet flange of the exhaust manifold tends to deteriorate.

[0004]
An object of the present invention is to provide an exhaust manifold for an engine with which deterioration of sealability between the cylinder head and the exhaust inlet flange of the exhaust manifold can be suppressed.

[0005]
«Process of Arriving at the Invention»
The inventors of the present invention have studied an exhaust manifold for an engine, to make the following findings.

While the engine is driven, since streams of high-temperature exhaust having passed through the branch pipes merge and pass through the exhaust merging portion, the thermal storage capacity of the wall of the exhaust merging portion is greater than that of the branch pipes. Therefore, the temperature dropping rate difference, and eventually the temperature difference, between them after the engine is stopped become great. Accordingly, due to the thermal strain of the exhaust manifold, sealability between the cylinder head and the exhaust inlet flange of the exhaust manifold tends to deteriorate. In particular, this problem becomes noticeable after heavy-load driving, which is associated with high-temperature exhaust.

The inventors of the present invention have arrived at the present invention based on such findings.

[Means for Solving Problems]

[0006]
(Invention According to claim 1)

The inventive particular matters according to claim 1 are as follows.

As shown in Figs. 1A to 3B, an exhaust manifold for an engine includes an exhaust merging portion (2) arranged at a center of the exhaust manifold (1); a plurality of branch pipes (3), (3) arranged at both ends of the exhaust merging portion (2); and an exhaust inlet flange (4) provided to each of the branch pipes (3) to be attached to a cylinder head, wherein in forming a rib-like opposite-head side built-up portion (7) at and along a longitudinal direction of an opposite-head side face (1b) out of a head side face (1a) of the exhaust manifold (1) facing the cylinder head and the opposite-head side face (1b) being opposite to the head side face (1a), the opposite-head side built-up portions (7), (7) are formed at the branch pipes (3), (3) on the both ends, and the opposite-head side face (1b) with no opposite-head side built-up portion (7) is formed at the exhaust merging portion (2).

[0007] (Invention According to claim 3)
The inventive particular matters according to claim 3 are as follows.
As shown in Figs.4A and 4B, an exhaust manifold for an engine includes an exhaust merging portion (2) arranged at a center of the exhaust manifold (1); a plurality of branch pipes (3), (3) arranged at both ends of the exhaust merging portion (2); and an exhaust inlet flange (4) provided to each of the branch pipes (3) to be attached to a cylinder head, wherein in forming a rib-like head side built-up portion (8) at and along a longitudinal direction of a head side face (la) of the exhaust manifold (1) facing the cylinder head, the head side built-up portions (8), (8) are formed at the branch pipes (3), (3) on the both ends, and the head side face (la) with no head side built-up portion (8) is formed at the exhaust merging portion (2).

SUMMARY OF THE INVENTION [Effect of the Invention]
[0008] (Invention According to Claim 1)

The invention according to claim 1 exhibits the following effect.
«Effect»

It becomes possible to suppress deterioration of sealability between the cylinder head and the exhaust inlet flange of the exhaust manifold.

As illustrated in Figs. 1A to 3B, since the opposite-head side built-up portions (7) (7) are formed at the branch pipes (3) (3) on the both ends, and the opposite-head side face (1b) with no opposite-head side built-up portion (7) is formed at the exhaust merging portion (2), the thermal storage capacity of the wall of the branch pipes (3) (3) while the engine is driven approximates that of the exhaust merging portion (2). Accordingly, the temperature dropping rate difference, and eventually the temperature difference, between them after the driving engine is stopped become small, and the thermal strain of the exhaust manifold (1) is suppressed. Therefore, deterioration of sealability between the cylinder head and the exhaust inlet flange (4) of the exhaust manifold (1) can be suppressed.

[0009] (Invention According to Claim 2)

The invention according to claim 2 exhibits the following effect in addition to the effect achieved by the invention according to claim 1.
«Effect»

The thermal strain of the exhaust manifold is suppressed.

As illustrated in Figs. 2A to 3B, since the function similar to that obtained by the opposite-head side built-up portion (7) can be obtained by the head side built-up portion (8) also, the thermal strain of the exhaust manifold (1) is suppressed. Further, the exhaust manifold (1) is reinforced by both the rib-like head side built-up portion (8) and the opposite-head side built-up portion (7). This also contributes toward suppressing the thermal strain of the exhaust manifold (1).

[0010] (Invention According to Claim 3)
The invention according to claim 3 exhibits the following effect. «Effect»
It becomes possible to suppress deterioration of sealability between the cylinder head and the exhaust inlet flange of the exhaust manifold.

As illustrated in Figs. 4A and 4B, since the head side built-up portions (8) (8) are formed at the branch pipes (3) (3) on the both ends, and the head side face (la) with no head side built-up portion (8) is formed at the exhaust merging portion (2), the thermal storage capacity of the wall of the branch pipes (3) (3) while the engine is driven approximates that of the exhaust merging portion (2). Accordingly, the temperature dropping rate difference, and eventually the temperature difference, between them after the driving engine is stopped become small, and the thermal strain of the exhaust manifold (1) is suppressed. Therefore, deterioration of sealability between the cylinder head and the exhaust inlet flange (4) of the exhaust manifold (1) can be suppressed.

[0011]
(Invention According to Claim 4)

The invention according to claim 4 exhibits the following effect in addition to the effect achieved by the invention according to any one of claims 1 to 3.
«Effect»

The thermal strain of the exhaust manifold is suppressed.
As illustrated in Figs. 1A to 4B, the exhaust merging portion (2) is provided with the exhaust inlet pipe (2a) and the exhaust outlet pipe (2b) lead out upward from the exhaust inlet pipe (2a); the exhaust outlet flange (6) is formed at the lead-out end of the exhaust outlet pipe (2b); and the rib-like top face built-up portion (10) is formed at the top face (5) of the branch pipe (3) while no rib-like built-up portion is formed at the bottom face of the branch pipe (3). Accordingly, the thermal storage capacity on the top side of the exhaust merging portion (2) and that on the top side of the branch pipe (3) approximate a state of equilibrium. Thus, the temperature dropping rate difference, and eventually the temperature difference, between them after the driving engine is stopped become small and, therefore, the thermal strain of the exhaust manifold (1) is suppressed.

[0012] (Invention According to Claim 5)
The invention according to claim 5 exhibits the following effect in addition to the effect achieved by the invention according to claim 4.
«Effect»
The top face built-up portion will present no obstacle in attaching a manifold attaching bolt.

As illustrated in Figs. 1A to 4B, the rib-like top face built-up portion (10) is aligned along the direction crossing the longitudinal direction of the exhaust manifold (1), and the top face built-up portion (10) is used as the bolt inserting boss (11) for a manifold attaching bolt. Therefore, the top face built-up portion (10) will present no obstacle in attaching the manifold attaching bolt.

BRIEF DESCRIPTION OF THE DRAWINGS [0013]
Figs. 1 A, IB, 1C, ID, and IE are diagrams illustrating an exhaust manifold according to a first embodiment of the present invention, in which Fig. 1A is a plan view, Fig. 1B.is a side view, Fig. 1C is a cross sectional view taken along line C-C in Fig. 1B, Fig. 1D is a cross sectional view taken along line D-D in Fig. 1B, and Fig. 1E is a view in the direction of arrow E in Fig. 1B;

Figs. 2A and 2B are diagrams illustrating an exhaust manifold according to a second embodiment of the present invention, in which Fig. 2A is a plan view and Fig. 2B is a side view;

Figs. 3 A and 3B are diagrams illustrating an exhaust manifold according to a third embodiment of the present invention, in which Fig. 3A is a plan view and Fig. 3B is a side view; and

Figs. 4A and 4B are diagrams illustrating an exhaust manifold according to a fourth embodiment of the present invention, in which Fig. 4 A is a plan view and Fig. 4B is a side view.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0014]

Figs. 1A to 4B are diagrams illustrating an exhaust manifold for an engine according to embodiments of the present invention, in which Figs. 1A to IE correspond to a first embodiment, Figs. 2A and 2B correspond to a second embodiment, Figs. 3A and 3B correspond to a third embodiment, and Figs. 4A and 4B correspond to a fourth embodiment.

In each of the embodiments, a description will be given of an exhaust manifold for a vertical inline-four cylinder diesel engine equipped with a supercharger.

[0015]

Firstly, a description will be given of the first embodiment.

As shown in Figs. 1A and IB, an exhaust manifold (1) includes an exhaust merging portion (2) arranged at the center of the exhaust manifold (1), and a plurality of branch pipes (3) (3) arranged at the both ends of the exhaust merging portion (2). Each branch pipe (3) is provided with an exhaust inlet flange (4) to be attached to a cylinder head.

The exhaust merging portion (2) is provided with an exhaust inlet pipe (2a) and an exhaust outlet pipe (2b) lead out from the exhaust inlet pipe (2a), and an exhaust outlet flange (6) is formed at the lead-out end of the exhaust outlet pipe (2b). To the exhaust outlet flange (6), a supercharger is attached. As shown in Fig. IB, the exhaust outlet pipe (2b) is lead out upward from the exhaust inlet pipe (2a), and a bottom wall (9) of the exhaust inlet pipe (2a) positioned below the exhaust outlet pipe (2b) is depressed upward. The branch pipe (3) is a pipe for allowing exhaust from the corresponding cylinder to pass, and the exhaust merging portion (2) is the portion where streams of exhaust from a plurality of branch pipes (3) (3) merge.

In a planar view, the exhaust manifold (1) forms a bow-shaped pipe with the exhaust merging portion (2) and a pair of branch pipes (3) (3) on the both ends, and a pair of centrally-positioned branch pipes (3) (3) is formed on the cylinder head side relative to the bow-shaped pipe. The adjacent exhaust inlet flanges (4) (4) of the pair of centrally-positioned branch pipes (3) (3) are coupled to each other by a bridging portion (12).

[0016]
As shown in Fig. 1(A), in forming the rib-like opposite-head side built-up portion (7) at and along the longitudinal direction of the opposite-head side face (lb) out of the head side face (la) of the exhaust manifold (1) facing the cylinder head and the opposite-head side face (lb) being opposite to the head side face (la), the opposite-head side built-up portions (7), (7) are formed at the branch pipes (3), (3) on the both ends, and the opposite-head side face (lb) with no opposite-head side built-up portion (7) is formed at the exhaust merging portion (2).

[0017]

As shown in Figs. 1A and IB, the exhaust merging portion (2) is provided with the exhaust inlet pipe (2a) and the exhaust outlet pipe (2b) lead out upward from the exhaust inlet pipe (2a). The exhaust outlet flange (6) is formed at the lead-out end of the exhaust outlet pipe (2b). A rib-like top face built-up portion (10) is formed at a top face (5) of each branch pipe (3), and no rib-like built-up portion is formed at the-bottom face of each branch pipe (3).

[0018]
As shown in Figs. 1 A, IB, 1C, and IE, the rib-like top face built-up portion (10) is aligned along the direction crossing the longitudinal direction of the exhaust manifold (1), and the top face built-up portion (10) is used as a bolt inserting boss (11) for a manifold attaching bolt.

Only the top face built-up portions (10) (10) of the branch pipes (3) (3) on the opposite sides are each used as the bolt inserting boss (11), and the top face built-up portions (10) (10) of the pair of branch pipes (3) (3) at the center are not used as the bolt inserting boss (11).

[0019]
The second embodiment shown in Figs. 2A and 2B and the third embodiment shown in Figs. 3 A and 3B include a head side built-up portion (8) in addition to the configuration of the first embodiment.

That is, as shown in Fig. 2A or Fig. 3 A, in forming the rib-like head side built-up portion (8) at and along the longitudinal direction of a head side face (la) of the exhaust manifold (1), the head side built-up portions (8) (8) are formed at the branch pipes (3) (3) at the both ends, and the head side face (la) with no head side built-up portion (8) is formed at the exhaust merging portion (2).

In the second embodiment, since both the opposite-head side built-up portion (7) and the head side built-up portion (8) are included, the vertical width (7a) of the opposite-head side built-up portion (7) is reduced as compared to that in the first embodiment, thereby achieving a reduction in the volume.

In the third embodiment, though both the opposite-head side built-up portion (7) and the head side built-up portion (8) are included, they are each small in the horizontal projecting dimension. Accordingly, the vertical width (7a) of the opposite-head side built-up portion (7) is increased to be greater than that in the first embodiment, to secure the volume.

Further, in the second embodiment and the third embodiment, all the adjacent exhaust inlet flanges (4) (4) are coupled to each other by the bridging portion (12).

Other configuration is similar to that in the first embodiment, and the elements in Figs. 2A to 3 B being identical to those in the first embodiment are denoted by the identical reference characters used in Figs. 1A to 1E.

[0020]
In the fourth embodiment shown in Figs. 4A and 4B, the opposite-head side built-up portion (7) is not provided and only the head side built-up portion (8) is provided.

As shown in Fig. 4A, in forming the rib-like head side built-up portion (8) at and along the longitudinal direction of the head side face (la) of the exhaust manifold (1) facing the cylinder head, the head side built-up portions (8), (8) are formed at the branch pipes (3), (3) on the both ends, and the head side face (la) with no head side built-up portion (8) is formed at the exhaust merging portion (2).

Further, in the fourth embodiment, similar to the second and third embodiments, all the adjacent exhaust inlet flanges (4) (4) are coupled to each other by the bridging portion (12).

Other configuration is similar to that in the first embodiment, and the elements in Figs. 4A and 4B being identical to those in the first embodiment are denoted by the identical reference characters used in Figs. 1A to IE.

While the embodiments of the present invention have been described as to the exhaust manifold for a diesel engine equipped with a supercharger, the present invention is not limited thereto, and it goes without saying that the present invention is also applicable to an exhaust manifold for a naturally aspirated diesel engine, an exhaust manifold for a spark-ignition engine equipped with a supercharger, and an exhaust manifold for a naturally aspirated spark-ignition engine.

What is claimed is:

1. An exhaust manifold for an engine comprising:
an exhaust merging portion 2 arranged at a center of the exhaust manifold 1;
a plurality of branch pipes 3, 3 arranged at both ends of the exhaust merging portion 2; and
an exhaust inlet flange 4 provided to each of the branch pipes 3 to be attached to a cylinder head, wherein

in forming a rib-like opposite-head side built-up portion 7 at and along a longitudinal direction of an opposite-head side face 1b out of a head side face la of the exhaust manifold 1 facing the cylinder head and the opposite-head side face 1b being opposite to the head side face 1 a,

the opposite-head side built-up portions 7, 7 are formed at the branch pipes 3, 3 on the both ends, and the opposite-head side face 1b with no opposite-head side built-up portion 7 is formed at the exhaust merging portion 2.

2. The exhaust manifold for an engine according to claim 1, wherein

in forming a rib-like head side built-up portion 8 at and along a longitudinal direction of the head side face la of the exhaust manifold 1,

the head side built-up portions 8, 8 are formed at the branch pipes 3, 3 on the both ends, and the head side face la with no head side built-up portion 8 is formed at the exhaust merging portion 2.

3. An exhaust manifold for an engine comprising:
an exhaust merging portion 2 arranged at a center of the exhaust manifold 1;

a plurality of branch pipes 3, 3 arranged at both ends of the exhaust merging portion 2; and
an exhaust inlet flange 4 provided to each of the branch pipes 3 to be attached to a cylinder head, wherein
in forming a rib-like head side built-up portion 8 at and along a longitudinal direction of a head side face la of the exhaust manifold 1 facing the cylinder head,
the head side built-up portions 8, 8 are formed at the branch pipes 3, 3 on the both ends, and the head side face la with no head side built-up portion 8 is formed at the exhaust merging portion 2.

4. The exhaust manifold for an engine according to any one of claims 1 to 3, further comprising:
an exhaust inlet pipe 2a provided to the exhaust merging portion 2;
an exhaust outlet pipe 2b lead out upward from the exhaust inlet pipe 2a;
an exhaust outlet flange 6 formed at a lead-out end of the exhaust outlet pipe 2b; and
a rib-like top face built-up portion 10 formed at a top face 5 of the branch pipe 3, wherein
no rib-like built-up portion is formed at a bottom face of the branch pipe 3.

5. The exhaust manifold for an engine according to claim 4, wherein the rib-like top face built-up portion 10 is aligned along a direction crossing a longitudinal direction of the exhaust manifold 1, the top face built-up portion 10 being used as a bolt inserting boss 11 for a manifold attaching bolt. Dated this 31 day of July 2013