JPS6034770Y2 - Internal combustion engine intake manifold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an intake manifold that improves the uniformity of distribution of recirculated exhaust gas to each cylinder, mainly in a multi-cylinder internal combustion engine for automobiles.

In order to reduce NOx emitted from an internal combustion engine, it is known that part of the exhaust gas is returned to the intake air (EGR), but the distribution of the exhaust gas that is returned to the intake manifold to each cylinder is determined by the recirculation rate. When the recirculation ratio was small, there was not much of a problem, but as the recirculation rate became large, the distribution became uneven depending on the cylinder, causing instability in driveability.

By the way, in the past, as shown in Figures 1 and 2, in the vicinity of the carburetor mounting seat 2 at the gathering part of the exhaust manifold 1, in order to reduce the installation space, it was previously installed along the outer wall of the manifold 1. Connect the exhaust recirculation passage 3 that has been
In most cases, the air is communicated with the intake air through ports a and 4b, but in this case, the flow rate on the nozzle port 4a side inevitably increases due to the inertia of the recirculated exhaust flow, causing excessive exhaust to the 11th and 2nd cylinder side. It had the disadvantage of being refluxed.

Further, although not shown, in the case where the nozzle is provided directly below the carburetor, there are problems in that the secondary venturi carburetor is contaminated with exhaust gas, and there are space problems.

The present invention solves these problems by bending the exhaust gas recirculation passage almost at right angles and creating a communication passage that almost eliminates the directionality based on the inertia of the recirculated exhaust flow, and eliminates the directionality based on the inertia that remains. Intake that aims to equalize the distribution of recirculated exhaust gas to each cylinder by making the diameter of the nozzle hole at the front of the two nozzle openings in the manifold smaller in the direction in which the recirculated exhaust gas travels to correct the imbalance in distribution due to directionality. It provides a manifold.

The present invention will be described below with reference to some examples.

The embodiment shown in Figs. 3 and 4 shows the main part of the intake manifold of a four-cylinder engine, and the manifold 1 has branch parts corresponding to the first to fourth cylinders, and a carburetor attached to the converging part. It has a seat 2 and is formed in the same manner as in FIG.

The exhaust gas recirculation passage 14 formed along the side wall 13 of the main body is connected to a communication passage 15 bent downward at an approximately right angle near the carburetor mounting seat 2, and furthermore, the exhaust gas recirculation passage 14 formed along the side wall 13 of the main body is connected to a communication passage 15 that is bent downward at an approximately right angle, and is also approximately perpendicular to the communication passage 15. The branch passages 16a and 16b are divided into two, and the branch passages 16a and 16b have a jet pipe 20a,
20b and opens into the intake passage 18 in the manifold.

Of these pipes 20a and 20b, the pipe 20a at the front in the direction of movement of the recirculated exhaust gas is made smaller in diameter than the other pipe 20b to reduce the directionality due to the inertia of the exhaust flow.

In other words, the recirculated exhaust gas flowing in the direction of the exhaust gas recirculation passage 14 is bent from the communication passage 15 to the branch passages 16a and 16b, so that the directionality based on inertia is almost eliminated, and the pipe 20a has a different effective diameter. Since the exhaust gas is ejected from the pipes 20a and 20b, substantially the same amount of exhaust gas is returned to the left and right intake passages 18 in the manifolds from both the pipes 20a and 20b.

As a result, the distribution of the recirculated exhaust gas to the first to fourth cylinders becomes almost uniform, and stable combustion can be ensured between each cylinder of the engine.

This is shown in Fig. 5 in comparison with the conventional example. In particular, with the present invention, even if the average exhaust gas recirculation rate (EGR rate) is increased to around 20%, almost no imbalance occurs between each cylinder. On the other hand, in the conventional example (in this case, the intake manifold shown in Figs. 1 and 2), as the average recirculation rate increases, the distribution becomes unbalanced, and even if the overall N
Even if the amount of Ox discharged is the same, as shown in FIG. 6, the combustion stability limit may be exceeded in the cylinders in which excessive recirculation occurs, causing practical problems such as poor drivability.

In other words, when trying to reduce NOx through EGR without impairing drivability, it is essential to maintain uniform EGR distribution among the cylinders of a multi-cylinder engine. It is something to be solved.

In order to change the direction of ejection from the pipes 20a, 20b, as shown in FIG. 8, the tips of the pipes 20a, 2ob are cut off diagonally, or the tips are closed and a small hole is made in the peripheral wall.

Further, in the above embodiment, the jet pipes 20at20b are fitted into the branch passages 16a and 16b to change their inner diameters, but the diameter of the jet openings of the branch passages 16a and 16b is set to be smaller in the forward direction of movement, and direct reflux is carried out. It is clear that a similar effect can be obtained by blowing out the exhaust gas.

As described above, the present invention almost eliminates the flow directionality based on the inertia of the recirculated exhaust gas by using the communication passage bent from the exhaust gas recirculation passage, and furthermore eliminates the imbalance in the distribution of the recirculated exhaust gas due to the remaining directionality. Of the two nozzles that open in the manifold, the diameter of the nozzle at the front in the direction of movement of the recirculated exhaust gas is made smaller, allowing the recirculated exhaust gas to be distributed almost uniformly to each branch, thereby reducing the imbalance in combustion between the cylinders. This will prevent engine instability caused by excessive exhaust recirculation and realize effective NOx reduction measures without impairing engine performance or fuel efficiency even under high-rate exhaust recirculation.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway plan view of a conventional intake manifold, Fig. 2 is an enlarged sectional view of Fig. 1, Fig. 3 is a cutaway plan view of the main part of the embodiment of the present invention, and Fig. 4 is a cross section of a pipe. An enlarged view, FIG. 5 is an explanatory diagram showing the distribution ratio of recirculated exhaust gas to each cylinder in comparison with the conventional one, and FIG. 6 is an explanatory diagram showing the relationship between the exhaust gas recirculation rate and the amount of NOx generated. 1... Manifold body, 2... Carburetor mounting seat, 14... Exhaust recirculation passage 15...
...Communication path, 16a, 16b... Branch path,
20a, 20b...Blowout pipe.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine equipped with an exhaust gas recirculation device that recirculates a portion of exhaust gas into intake air, an exhaust gas recirculation passage formed along an outer wall of an intake manifold body, and nozzles opening at at least two locations in the intake passage in the manifold gathering part; are connected via a communication passage bent from the exhaust gas recirculation passage near the carburetor mounting seat, and the diameter of the nozzle at the front of the nozzle in the direction of movement of the recirculated exhaust is smaller than the diameter of the other nozzle. An intake manifold for an internal combustion engine, characterized in that it is formed as follows.