JPH0783048A - Car exhaust manifold - Google Patents

Abstract

(57) [Abstract] [Purpose] To simplify the production of the exhaust manifold block of a 4-cylinder engine and to increase the engine output. [Structure] In an exhaust manifold block 1 of a four-cylinder engine mounted on an automobile, a first collecting pipe 12 is formed by collecting a pair of adjacent branches 3 and 4 whose ignition order is not continuous.
And the first collecting pipe 12 is assembled with another pair of branches 2 and 5 which are adjacent to each other and are not consecutive in ignition order to form a second collecting pipe.
14 was formed, and the cross-sectional area of the first collecting pipe 12 was made substantially equal to the cross-sectional area of each branch. Branches 3 and 4 next to each other
Since the exhaust manifold block 1 has a shape in which the branches 2 and 5 adjacent to the first collecting pipe 12 are joined in order, only one core 8 is required for casting, and the exhaust gas flows smoothly. become.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold of an automobile equipped with a 4-cylinder engine.

[0002]

2. Description of the Related Art The exhaust system of an engine mounted on an automobile is
A catalyst and a muffler are connected in series through an exhaust pipe to an exhaust manifold block composed of a plurality of branches connected to an exhaust port of each cylinder. Therefore, it takes some load to release the exhaust gas, so even when connecting the branches, the flow of the exhaust gas at the confluence point should be smooth, and the space in the engine room should be taken into consideration. Has been decided.

The exhaust manifold block 1 shown in FIGS. 4 and 5 has four cylinders.
The bolts 3, 4 and 5 are attached to a cylinder head (not shown) by bolts 6. This branch 2,
3, 4, 5 extend toward the collecting portion 7 and are connected to each other. Since this structure has one outlet, only one exhaust pipe needs to be connected, and it is simple because only one core is used during casting.

Here, FIG. 6A shows the amount of exhaust generated by the ignition sequence of each cylinder of the exhaust manifold block 1 shown in FIG. Then, since the exhaust gas of the exhaust manifold block 1 merges with the collecting portion 7, it becomes a continuous exhaust flow as shown in FIG. 6B, but the hatched portions cause exhaust interference.

On the other hand, in the exhaust manifold block 1 shown in FIGS. 7 and 8, the branches 3 and 4 are assembled to form the branches 2 and 5.
The number of exhaust pipes to be connected is two, but the exhaust pipe does not cause exhaust interference as shown in FIG. 6C. Therefore, the output of the engine is increased. The exhaust manifold block 1 shown in FIGS. 9 and 10 has a single exhaust pipe connected thereto (see Japanese Utility Model Laid-Open No. 52-152912). In addition to this, an exhaust manifold block having a structure in which two branch pipes are formed by dividing and collecting branches so as not to cause exhaust interference has been proposed (see Japanese Utility Model Publication No. 51-55117). .

[0006]

By the way, in the exhaust manifold block 1 shown in FIG. 4, immediately before the collecting portion of each branch, the passages are adjacent to each other and their cross-sectional areas are integrated to form a large volume space portion. Has been done. Therefore, the exhaust gas enters the space portion and expands, and then enters the collecting portion 7 and contracts. Therefore, the smooth flow of the exhaust gas is obstructed, and the engine output is reduced. Further, since the flow of exhaust gas becomes non-uniform, even if the O ₂ sensor is attached to the collecting portion 7, it is not possible to accurately measure the oxygen concentration in the exhaust gas.

On the other hand, the exhaust manifold block 1 shown in FIGS. 7 and 9 described above enables a smooth flow of exhaust gas. However, each branch 2, 3, 4, 5
Since the relative positions of the two become three-dimensional and two cores are required during casting, the production is complicated. For example, the branches 2, 3, 4, 5 of the exhaust manifold block 1 shown in FIG.
Is divided into two as shown in FIG. 11, and two cores 8 are prepared and cast by a mold 9 as shown in FIG. In this method, if a burr is generated in the branch connection portion 10, it takes time and effort for molding, and the weight increases, resulting in an increase in cost. Further, in these exhaust manifold blocks 1, the bolts 6 are located behind any of the branches, which makes it difficult to tighten the bolts 6.

An object of the present invention is to provide an automobile exhaust manifold for improving engine output, which is easy to manufacture.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first exhaust gas manifold block of a multi-cylinder engine mounted on an automobile, by collecting a pair of adjacent branches whose ignition order is not continuous. A collecting pipe is formed, and the first collecting pipe is assembled with another pair of adjacent branches whose firing order is not continuous to form a second collecting pipe, and a cross-sectional area of the first collecting pipe is cut off from each branch. It is characterized in that it is almost equal to the area.

[0010]

Since the present invention is configured as described above, the interval between the cylinder tightening portions between each branch of the first collecting pipe and another adjacent branch whose ignition sequence is not continuous becomes wide, and , Can be made by setting each branch in a position where it does not intersect. Further, since the branches whose ignition order is not continuous are first assembled, the flow of exhaust gas is made smooth.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, in the exhaust manifold block 1 of a four-cylinder engine, the exhaust of the exhaust manifold block 1 according to the ignition order of the engine is divided into the branch 2
(1st), branch 3 (2nd), branch 5 (3rd), branch 4 (4th) are performed in this order. Further, as shown in the figure, the branches 3 and 4 are assembled to form the first collecting pipe 12 from the first collecting portion 11,
The branches 2 and 5 are assembled together with the first collecting pipe 12 to form the second collecting pipe 14 from the second collecting portion 13. Therefore, the first collecting portion 11 is located upstream of the second collecting portion 13, the cross-sectional area of the first collecting pipe 12 is substantially equal to that of each branch, and the second collecting pipe 14 does not hinder the flow. So that each branch has a larger cross-sectional area.

Further, since the exhaust manifold block 1 connects adjacent ones of the branches 2, 3, 4, 5 with each other, the branches are arranged side by side in the mold 9 as shown in FIGS. It is possible to cast and manufacture using one core 8.

In the four-cylinder engine thus constructed, the relationship between the two cylinders connecting the branch 3 and the branch 4 is 360 degrees in phase, so that exhaust gas flows alternately, so that the branches 3 and 4 are assembled. Does not cause exhaust interference,
Moreover, since the cross-sectional area of the first collecting pipe 12 hardly changes, the exhaust gas smoothly flows to the second collecting portion 13. Further, in the second collecting portion 13, since the three pipes are gathered at an angle close to 90 degrees, the space portion associated with the gathering is smaller than that of gathering four pipes.

That is, the exhaust manifold block 1 of the embodiment can obtain the same exhaust action as that of the conventional exhaust manifold block 1 shown in FIG. 7 or FIG.
Since the collecting portions 11 and 13 are provided at different positions on the upstream side and the downstream side, the last part of the exhaust stroke produces a suction effect of the branch performing the next exhaust stroke, and the output of the engine can be increased. In addition, conventionally, the flow of exhaust gas is unstable and O ₂
Since the flow of the exhaust gas becomes uniform even in a portion that was not suitable for measurement, it is possible to accurately measure the oxygen concentration in the exhaust gas by installing an O ₂ sensor.

In addition, the space between the branches 2 and 3 and the space between the branches 4 and 5 are widened because the exhaust passage is made compact, so that there is a margin around the bolts of the exhaust manifold block 1 and bolt tightening is possible. Will be easier. Also, in the production of the exhaust manifold block 1, since only one core 8 is used, casting is easy, deburring is not required, and the weight is reduced as compared with that in FIG. 7.
The cost can be reduced. Also in the case of the structure shown in FIG. 4, the first collecting pipe 12 is compact, so that weight reduction and cost reduction can be achieved.

[0016]

Since the present invention is configured as described above, the exhaust manifold block can be easily manufactured because the core used for casting is one because the branches do not intersect each other. Can be manufactured.
Further, since the area around the tightening portion of the exhaust manifold block is compact, tightening of the bolts becomes easy and the working time can be shortened. Also, due to the structure, the exhaust gas smoothly flows through the branch inside the collecting pipe,
Further, the engine output is improved by the suction effect in the collecting portion. Further, it is possible to accurately measure the oxygen concentration by attaching the O ₂ sensor in the set section.

[Brief description of drawings]

FIG. 1 is a perspective view of an exhaust manifold block of a four-cylinder engine according to an embodiment of the present invention.

FIG. 2 is a side view of the exhaust manifold block shown in FIG.

FIG. 3 is a schematic view of a mold for manufacturing the exhaust manifold block shown in FIG.

FIG. 4 is a perspective view of an exhaust manifold block of a conventional 4-cylinder engine.

5 is a side view of the exhaust manifold block shown in FIG. 4. FIG.

FIG. 6 is a graph showing an exhaust cycle of an exhaust manifold block of a 4-cylinder engine.

FIG. 7 is a perspective view of another exhaust manifold block of a conventional four-cylinder engine.

8 is a side view of the exhaust manifold block shown in FIG. 7. FIG.

FIG. 9 is a perspective view of another exhaust manifold block of a conventional four-cylinder engine.

10 is a side view of the exhaust manifold block shown in FIG. 9. FIG.

11 is a perspective view showing a branch of the exhaust manifold block shown in FIG. 9. FIG.

FIG. 12 is a schematic diagram of a mold for manufacturing the exhaust manifold block shown in FIG.

[Explanation of symbols]

 1 Exhaust manifold block 2 Branch 3 Branch 4 Branch 5 Branch 12 1st collecting pipe 14 2nd collecting pipe

Claims (1)

[Claims] 1. In an exhaust manifold block of a multi-cylinder engine mounted on an automobile, a pair of adjacent branches whose ignition order is not continuous are collected to form a first collecting pipe, and the first collecting pipe is used for another ignition. An exhaust manifold for an automobile, characterized in that a second collecting pipe is formed by gathering a set of adjacent branches that are not consecutive in order, and a cross-sectional area of the first collecting pipe is substantially equal to a cross-sectional area of each branch.