JPS6045292B2 - Exhaust manifold of supercharged internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust manifold for a supercharged internal combustion engine.

Since considerable pressure fluctuations occur within the exhaust pipe as the exhaust gas is blown out of the internal combustion engine, the quality of the exhaust pipe system has a relatively large effect on the performance of the internal combustion engine. As the exhaust valve opens, gas having enough energy to be expanded within the cylinder flows into the exhaust manifold.

It is becoming important to increase the recovery rate of this exhaust energy in the turbocharger turbine. Also, the large positive pressure wave generated at the exhaust valve outlet propagates within the manifold, is reflected by the turbine section, and returns as a negative pressure wave. The combination of these waves creates steady pressure oscillations within the exhaust manifold. On the other hand, if the length and diameter of the exhaust manifold are appropriately selected so that the primary or secondary negative pressure wave after the exhaust blows out is synchronized near the exhaust valve closing time, the residual gas in the cylinder can be blown out. Scavenging air will be improved and volumetric efficiency will be improved. However, in order to achieve the above-mentioned synchronization, the length of the exhaust manifold becomes quite long, and while the layout of the exhaust manifold is relatively free, such as in marine engines, the length of the exhaust manifold is affected by the overall configuration of vehicle engines. Due to constraints, I couldn't make it too long.

The present invention was developed in view of the above, and it not only reduces the diameter of the exhaust manifold, but also artificially generates a negative pressure wave within the exhaust manifold.
Blowdown energy is guided to the turbocharger turbine with as little attenuation as possible, and the negative pressure generated at the inlet prevents exhaust interference, improving scavenging efficiency and therefore volumetric efficiency. It is an object of the present invention to provide an exhaust manifold for a supercharged internal combustion engine.

The configuration will be explained below based on the embodiment shown in the drawings.

1 in the figure is a two-part manifold for 6 cylinders,
It is constructed symmetrically.

1a is the first branch pipe connected to the first cylinder, lb is the second branch pipe connected to the second cylinder, lc, ld, le,
lf is the 3rd, 4th, 5th...branch, and the 1st on the left
, the second and third branch pipes 1a, lb, and lc are connected to the collecting pipe 2a, and the fourth, fifth, and sixth branch pipes on the right side are connected to another collecting pipe 2b and led to the outlet. Each of the above branch pipes 1a, 1b,
Among 1c,..., the first on both sides farthest from the exit,
A bulge is formed on the inner surface of the side wall at the connection between each of the second to fifth branch pipes 1b to 1e, excluding the sixth branch pipes 1a and 1f, and the collecting pipes 2a and 2b, and further from the above-mentioned outlet of each connection part. 3a, 3b, 3c, 3d are provided, whereby each branch pipe 1b, except the branch pipe 1a, 1f which is farthest from the above-mentioned outlet.
1c,... and a connecting passage 4 connecting the collecting pipes 2a, 2b.
a, 4b, . . . are constricted to a smaller diameter than the other portions, and the collecting pipe passage 5a is further away from the outlet of the connection portion between each of the branch pipes 1b, 1c, .
, 5b, . . . are similarly narrowed to a smaller diameter than the other parts. Each reduction ratio is about 40 to 70%, preferably about 50 to 60%. Generally, the firing order of this type of internal combustion engine is 1-3-5-6-4-2,
The exhaust valves of adjacent cylinders open at intervals of 240 degrees in crank angle.

Further, in this type of internal combustion engine, the exhaust period is approximately 240 degrees (crank angle), and exhaust interference is likely to occur when the exhaust gases are combined into one collecting pipe. If the exhaust valve of the first cylinder is now opened, a large pressure wave will propagate to the first branch pipe 1a connected to the first cylinder.

In the conventional manifold, this pressure wave propagates to the second and third branch pipes 1b and 1c connected to the second and third cylinders, but in the manifold shown in FIG.
The pressure wave generated in Negative pressure is generated in the connecting passage 4a. Similarly, the pressure waves from the first and second branch pipes 1a and 1b are throttled and accelerated when passing through the collecting pipe passage 5b immediately before the connection between the third branch pipe 1c and the collecting pipe 2a, and the pressure waves from the third branch pipe 1c are accelerated. and the connecting passage 4 between the collecting pipe 2a and the collecting pipe 2a.
A negative pressure is created at b. Therefore, the first and sixth branch pipes 1a, 1 located on the most upstream side connected to the first and sixth cylinders on both end sides
Each branch pipe other than f becomes a negative pressure by opening the exhaust valve of the adjacent cylinder, and it is possible to improve the scavenging efficiency and volumetric efficiency of each cylinder connected thereto.

The table below compares the internal combustion engine performance when using a conventional exhaust manifold and when using the exhaust manifold according to the present invention.

In the table, ηROr% is the overall efficiency of the supercharger, S. F. C is the fuel consumption rate, A/F is the air-fuel ratio, and as is clear from this table, η. 5. F. It can be seen that the Cl volumetric efficiency and A/F1 boost ratio are improved in the internal combustion engine using the exhaust manifold according to the present invention compared to the conventional manifold.

This is due to improved scavenging efficiency by preventing exhaust interference and effective use of exhaust energy. In addition, when looking at the effect on cylinder scavenging efficiency by the cylinder longitudinal fluctuation pressure during valve polymerization, at the rated point, the conventional example is shown in Fig. 2A, and the present invention example is shown in Fig. 2B, respectively. Further, the torque points are shown in FIG. 3A in the conventional example and in FIG. 3B in the example of the present invention.

Note that the solid line in the figure shows the cylinder outlet pressure (exhaust valve outlet pressure), and the chain line shows the cylinder inlet pressure (intake valve inlet pressure). As is clear from this figure, in the example of the present invention, the cylinder outlet pressure (exhaust valve outlet pressure) becomes significantly negative at the rated point, and the cylinder outlet pressure (exhaust valve outlet pressure) also becomes significantly negative on average at the torque point. It was found that this has a great effect on the scavenging efficiency of the cylinder. In addition, T. D. C indicates top dead center, 10 indicates the intake valve open position, and EC indicates the exhaust valve closed position.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIGS. 2A and 2B and 3A and 3B are diagrams showing effects on cylinder scavenging efficiency of a conventional example and an example of the present invention. 1 is an exhaust manifold, 1a, 1b, 1c... are branch pipes, 2a, 2b are collecting pipes, 3a, 3b, 3c... are bulges, 4a, 4b... 5a, 5b... are passages.

Claims (1)

[Claims] 1 First and second connected to each of the plurality of cylinders
, 3rd...branch pipes 1a, 1b, 1c,...
In the exhaust manifold of a supercharged internal combustion engine, which is connected to the collecting pipes 2a, 2b and guided to the outlet, each of the branch pipes 1a, 1b, 1c, ... connected to the collecting pipes 2a, 2b,...
Each branch pipe 1 except the branch pipe farthest from the exit
Connecting passages 4a, 4b, . ...
... and collecting pipes 2a, 2b, respectively, and a collecting pipe passage 5a, 5b, . exhaust manifold.