JPH059459Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an intake system for an internal combustion engine suitable for performing inertial supercharging using intake pressure vibration.

[Conventional technology]

Some internal combustion engines employ an intake air supply system called inertial supercharging or resonance supercharging.

This device utilizes the fact that a negative pressure wave generated near the intake port at the start of intake propagates to the end of the intake pipe at the speed of sound, creating an intake pressure vibration that becomes a positive pressure wave and returns toward the intake port. There is. In other words, by matching the period of intake pressure oscillation and the opening/closing period of the intake valve so that the positive pressure wave is transmitted to the intake valve just before the intake valve closes, the air that has generated the positive pressure wave becomes inertial. Therefore, it is pushed into the cylinder, and the intake air filling efficiency is improved by supercharging due to this inertia.

However, in the past, intake ports with a fixed shape were used, and the swirl ratio of these was almost constant regardless of engine operating conditions, so it was difficult to handle injection engines that varied depending on engine speed and engine load. I couldn't always get the matching.

Therefore, Jitko No. 54-8246, Jitko No. 60-14169
As described in the publication, a swirl control valve is installed in a branch pipe that branches from the intake manifold and guides intake air to the combustion chamber of each cylinder, and the swirl ratio is changed according to the operating state of the engine.
A system has been proposed in which the intake air filling efficiency is constantly improved regardless of the operating state of the engine.

[Problems to be solved by the invention] However, the conventional device has a problem in that it requires movable members such as a swirl control valve and a complicated control device.

Furthermore, as shown in Japanese Patent Application Laid-open No. 56-27025, there is an intake system for an internal combustion engine in which a replenishment chamber of the required volume is connected to the intake passage in the vicinity of the intake valve, but the system becomes large and has multiple cylinders. It is not suitable for engines, and the constant flow of intake air into the combustion chamber from the supply chamber increases intake swirl even at high speeds. Generally, the fuel injection period expressed in crank angle as shown in Fig. 11 is longer in the higher speed range of the engine rotation, so as shown in Fig. 10, the fuel spray flowing in the swirl may interfere with the adjacent fuel spray. This may cause problems such as smoke generation. Therefore, it is necessary to weaken the swirl ratio as shown by the ideal line shown by the broken line in FIG. However, in the conventional intake system structure, the swirl ratio is almost constant over the entire operating range of the engine. Therefore, it is difficult to obtain a swirl ratio suitable for all operating conditions of the engine.

The present invention was developed in view of the above-mentioned conventional problems, and its purpose is to make the device compact and suitable for multi-cylinder engines, and to improve intake air filling efficiency without using a swirl control valve. An object of the present invention is to provide an intake device for an internal combustion engine that can obtain a swirl ratio that matches all operating conditions of the engine.

[Means to solve the problem]

In order to solve the above object, the present invention provides a structure in which each branch pipe that branches from the intake manifold and guides intake air to the combustion chamber of each cylinder and each resonance pipe whose one end faces each combustion chamber are installed in parallel to the intake manifold. At the same time, each air reservoir chamber with the required volume connected to the end of each resonance pipe is integrally provided in the intake manifold, and in the low speed range of the engine, as the air flows into each air reservoir chamber through each resonance pipe, the intake manifold The intake air from the intake manifold is guided to each combustion chamber, and in the engine high speed range, the intake air from the intake manifold is combined with the return intake air from each air storage chamber through each resonance pipe, and the intake swirl from the intake manifold is weakened. It is characterized in that the resonance tube is arranged so as to lead to the chamber.

[Effect]

By arranging each branch pipe and each resonant pipe in parallel and integrally providing the intake manifold, and providing each air reservoir chamber integrally with the intake manifold, the apparatus becomes compact and becomes an optimal device even for a multi-cylinder engine.

In addition, when the engine is operating in a low speed range, intake air from the intake manifold flows into each air reservoir chamber through each resonance pipe, and as the intake air flows in, the intake air from the intake manifold becomes stronger and is supplied to each combustion chamber. This makes it possible to strengthen the swirl ratio.

On the other hand, when the engine is operating in a high-speed range, the intake from the intake manifold is combined with the return intake from each air reservoir chamber via each resonance pipe, and is guided into each combustion chamber in a direction that weakens the intake swirl from the intake manifold. Thus, the swirl ratio can be weakened.

Therefore, resonance supercharging improves the filling efficiency of the intake air amount without using a swirl control valve, and also increases the swirl ratio in operating conditions in the low engine speed range and weakens the swirl ratio in operating conditions in the high engine speed range. This provides a swirl ratio that matches all operating conditions of the engine.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 and 2 show the structure of a preferred embodiment of the present invention. In the figure, engine 1
A branch pipe 18 that branches from the intake manifold 14 and guides intake air to the combustion chamber 16 of each cylinder is disposed at the intake port 12 of No. 0. Resonant pipes 20 are arranged in parallel to each branch pipe 18 and are integrally provided with the intake manifold 14 . Each resonance tube 20 has one end open and the opening faces the combustion chamber 16.
Each air reservoir chamber 22 having a required volume is connected to the other end and is integrally provided with the intake manifold 14 . Note that an intake valve 24 is provided in the intake port 12.

The flow of intake air at each crank angle in the branch pipe 18 and each resonance pipe 20 is in the direction of the arrows shown in FIGS. 3 and 4 in the engine low speed range and the engine high speed range.

Incidentally, the branch pipe 18, the resonance pipe 20, and the air reservoir chamber 22 have, for example, a cross-sectional area of the branch pipe 18 of 15 cm ² and a length of 50 cm, and a cross-sectional area of the resonance pipe 20 of 7 cm ² and a length of 60 cm.
cm, and the container volume of the air reservoir chamber 22 is 1100 ^cm3 .

And, per cylinder, combustion chamber (stroke volume) 1
In an internal combustion engine with a size of 2000 cm ³ and an intake system having the above dimensions, resonance occurs in the low speed range around 1100 rpm, the swirl is strengthened, and the intake air filling efficiency is increased.

Also, near 2200 rpm, high-speed resonance occurs, weakening swirl and increasing intake air filling efficiency.

Immediately after the intake valve opens near top dead center, the intake air begins to flow slightly (flow velocity ≒ 0), reaches its maximum flow velocity (flow velocity = maximum) in the middle of the intake valve opening period, and immediately before the intake valve closes near bottom dead center, the intake air begins to flow slightly (flow velocity ≒ 0). , the flow velocity becomes very small (flow velocity≈0).

In the engine low speed range shown in FIG. In the engine high speed range shown in FIG. 4, the intake air from the intake manifold 14 is combined with the return intake air from each air reservoir chamber 22 via each resonance pipe 20, and the intake air from the intake manifold is The pressure vibration mode is such that the intake air swirl from 14 is guided to each combustion chamber 16 in a direction that weakens it.

The pressure vibration mode and the velocity vibration mode are
At the end of the air reservoir chamber 22, the velocity amplitude is always 0 (node of velocity amplitude mode), and the intake manifold 14
Inside, the intake pulses (negative pressure waves) of all the cylinders merge with each other at different phases and cancel each other out, so the pressure amplitude becomes 0 (node of pressure oscillation mode).

Therefore, the first (low engine speed range) natural vibration mode is as shown in FIG. 3, and the second (engine high speed range) natural vibration mode is as shown in FIG. In other words, in a low engine speed range where low frequency intake vibration occurs, intake resonance occurs in the mode shown in Figure 3, and in a high engine speed range where high frequency intake vibration occurs, intake resonance occurs in the mode shown in Figure 4. occurs.

When the intake valve 24 is opened in the low speed range,
Intake air is supplied to each air reservoir chamber 22 through the resonance pipe 20, and the intake air intensified in the branch pipe 18 is supplied to each combustion chamber 16, thereby increasing the swirl ratio. When the intake valve 24 is closed, there is no effect due to the return of intake air from each air storage chamber 22.

On the other hand, in the high speed range, intake air is supplied to the air reservoir chamber 22 while the intake valve 24 is closed. Intake valve 2
When 4 is opened, the intake air stored in each air storage chamber 22 is returned to each combustion chamber 16, so it becomes difficult to supply intake air from each intake manifold 14 to each combustion chamber 16, and the swirl is weakened.

In this way, in this embodiment, each branch pipe 1
8 and each resonance pipe 20 are arranged side by side and integrally provided in the intake manifold 14, and each air reservoir chamber 22 connected to each resonance pipe 20 is provided integrally in the intake manifold 14, making it compact and suitable for multi-cylinder engines. Become the perfect device.

In addition, in the engine low speed range, the intake manifold 14
The intake air from the air chamber 2 passes through the resonance pipe 20
Since the fuel is supplied to each combustion chamber 16 as it flows into the combustion chamber 2, the swirl ratio can be increased as shown in FIG. In addition, in the engine high speed range, the intake air from the intake manifold 14 is combined with the return intake air from each air reservoir chamber 22 via each resonance pipe 20 to flow into each combustion chamber 16 in a direction that weakens the intake swirl from the intake manifold 14. Therefore, the swirl ratio can be weakened as shown in the figure. For this reason,
Even without using a swirl control valve as in the past, the filling efficiency (volume efficiency) of the intake air can be increased as shown in Figure 8, and the swirl control valve can be adjusted to suit all operating conditions of the engine as shown in Figure 9. You can get the ratio.

Furthermore, in the embodiment described above, when disposing the resonance tube 20, the resonance tube 20 is formed by disposing the partition plate 26 integrally within the branch tube 18; Depending on the method of inserting the partition plate 26, the shapes of the branch pipe 18 and the resonance pipe 20 can be arbitrarily configured.
Shown in figures a to d. When inserting the partition plate 26 into the branch pipe 18, as shown in FIG.
It is also possible to insert it into

Also, as shown in Fig. 7, 2 per cylinder
It is also possible to apply this embodiment to a device having two intake valves 24a and 24b. In this case, it is desirable that the port 30 be communicated on the downstream side, and that the resonance pipe 20 be directed upstream of the intake valve 24a, which is closer to the port 30 inlet.

[Effect of idea]

As explained above, according to the present invention, the device becomes compact and becomes optimal for multi-cylinder engines.
Furthermore, excellent effects can be obtained in that the intake air filling efficiency can be improved without using a swirl control valve, and a swirl ratio that is suitable for all operating conditions of the engine can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view of the main part showing an embodiment of the present invention, FIG. 2 is a cross-sectional view of the main part of the device shown in FIG.
Figure 3 is a diagram for explaining the effects of the engine in the low speed range.
Figure 4 is a diagram to explain the action in the engine high speed range.
Fig. 5 is a diagram showing an example of the shape of a branch pipe and a resonant pipe, Fig. 6
Figure 7 is a perspective view showing another embodiment of the partition plate, Figure 7 is a main part configuration diagram when this embodiment is applied to an engine having two intake valves per cylinder, and Figure 8 is the engine rotation speed. A diagram showing the relationship between and volumetric efficiency,
Figure 9 is a diagram showing the relationship between engine rotation speed and swirl ratio, Figure 10 is a plan view showing the fuel spray state, Figure 11 is a diagram showing the relationship between engine rotation speed and injection period, and Figure 12 is a diagram showing the relationship between engine rotation speed and injection period. FIG. 3 is a diagram showing a conventional swirl ratio and an ideal swirl ratio with respect to engine rotational speed. 14...Intake manifold, 16...Combustion chamber,
18... Branch pipe, 20... Resonance pipe, 22... Air reservoir chamber, 24, 24a, 24b... Intake valve, 26
...Partition board.

Claims (1)

[Scope of utility model registration request] Each branch pipe that branches from the intake manifold and guides intake air to the combustion chamber of each cylinder and each resonance pipe whose one end faces each combustion chamber are arranged side by side and integrated with the intake manifold, and at the end of each resonance pipe. Each air reservoir chamber with the required volume to be connected is provided integrally with the intake manifold, and in the engine low speed range, the intake air from the intake manifold is guided to each combustion chamber through each resonance pipe as it flows into each air reservoir chamber, and the engine In the high speed range, the resonance pipes are arranged so that the intake air from the intake manifold is combined with the return intake air from each air storage chamber through each resonance pipe, and is guided to each combustion chamber in a direction that weakens the intake swirl from the intake manifold. An intake system for an internal combustion engine characterized by: