JPS61190115A - Intake air device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent blow-back of intake air under low speed by arranging a gate valve openable only under high speed in the intake path in upstream of one intake port of engine having two intake ports for every cylinder while providing a check valve in the intake path in upstream of another intake port. CONSTITUTION:A gate valve 21 openable only under high speed is arranged in an intake path 15 communicated to the intake port at the intake valve 11 side of engine having two intake valves 11, 12 for every cylinder while a check valve 22 comprised of a reed 22b is arranged in the intake path 16 communicated to the intake port at the intake valve 12 side. Said valve 21 will close under low speed of engine to take in the air only through the intake path 16 thus to block the gas in the cylinder to be blown back from the intake valve 12 to the intake path 16 upon overlap of intake/exhaust valve by mans of the check valve 22. Consequently, the output under low speed is increased to improve the fuel consumption and the exhaust characteristic while to improve the low speed performance even when overlapping the intake valve to high speed type.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a technique for improving an intake system for an internal combustion engine having a plurality of intake ports for each cylinder.

<Prior Art> As an example of an intake system for an internal combustion engine equipped with a plurality of intake ports, there is an intake system as shown in FIG.
(See No. 225356).

That is, for each cylinder, two intake valves 1a, 1b, two intake valves 2a, 2b, two exhaust valves 8a, 8b, and two exhaust ports 9 are provided.
a, 9b.

A butterfly-type opening/closing valve 3 is provided at one of the intake ports 2a and 2b, for example, the intake port 2b, and by closing the opening/closing valve 3 when the engine rotates at low speed (low speed range), only the other intake port 2a is closed. Intake air is introduced into the combustion chamber 4 from the combustion chamber 4. In this way, by taking in air only from one intake port 2a, a strong swirl is generated along the inner wall of the combustion chamber 4, and the blowback of intake air due to exhaust gas at the time of valve overlap is reduced. We are trying to improve combustion.

On the other hand, during high speed rotation (high speed range), the on-off valve 3 is opened.

By opening the two intake bows 2a and 2b, intake resistance is reduced, intake air filling efficiency is increased, and output is improved.

Further, since the on-off valve 3 is opened less frequently in the normal operating range, the two-way injector 5 is provided on the side of the intake port 2a, which is always open, in order to obtain stable air-fuel ratio control responsiveness. In addition, 6 is a spark plug.

<Problems to be Solved by the Invention> However, in the above-mentioned conventional example, the cross-sectional area (opening area) of the intake passage is simply halved in response to the blowback of intake air. That is, in an engine with a long overramp period in which the opening timing of the intake valve is advanced in anticipation of a delay in the introduction of intake air at high speed rotations, it is not possible to effectively prevent intake air blowback during low speed rotations where the intake inertia force is small. For this reason, when the engine rotates at low speed, the amount of intake air is small and the proportion of residual gas increases, causing a problem in that the filling efficiency is significantly reduced, that is, the output of the engine is reduced.

The present invention solves the above-mentioned disadvantages, effectively prevents intake air from blowing back during low-speed rotation, and improves engine charging efficiency.
The purpose of this is to improve the output when the engine rotates at low speeds.

(Means for solving the problem) Therefore, in the present invention, some intake ports are provided with on-off valves that are controlled to open and close according to engine speed, and other intake ports (low-speed rotation intake ports) are provided with on-off valves that are controlled to open and close according to engine speed. is equipped with a check valve to prevent backflow of intake air.

By providing the check valve in the intake port for low-speed rotation as described above, the blowback of intake air into the intake port is effectively prevented during low-speed rotation when the intake inertia force is small, and the filling efficiency of the engine is improved.

<Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view showing a first embodiment. In this embodiment, two intake valves 11.12 are provided for each cylinder of the internal combustion engine, and two intake ports 15, 16 and 2 are provided with these intake valves interposed therebetween.
Two exhaust valves 13, 14 and two exhaust ports 17a, 17b are provided.

Further, one of the intake ports 15 is equipped with an on-off valve 21 that is controlled to open and close depending on the engine speed, and the other intake port 16 is equipped with a reed valve 22 as a check valve. still,
6 is a spark plug, and 7 is a combustion chamber.

In the intake device having such a configuration, the opening/closing of the on-off valve 21 is as follows:
As shown in FIG. 2, this is performed by an actuator 23, and the operation of the actuator 23 is controlled by an output signal from a control device 24 to which detection signals such as engine speed and throttle opening are input. That is, the on-off valve 21 is closed when the engine rotates at low speed, and is opened when the engine rotates at medium and high speeds. Therefore, intake air is introduced into the combustion chamber 7 only from the intake port 16 during low speed rotation, and from both intake ports 15 and 16 during medium and high speed rotation.

During medium and high speed rotation, intake air is introduced into the combustion chamber 7 from both intake bows (15 and 16), making it possible to obtain high charging efficiency. At this time, the reed valve 22 installed in the intake port 16 causes intake resistance, but the effect is naturally smaller than when the reed valve 22 is installed in an intake device having only one intake port. Furthermore, when the intake air is introduced only from the intake port 16 during low-speed rotation, the amount of intake air is small, so the intake resistance of the reed valve 22 is negligible.

Here, the reed valve 22 will be explained in detail. As shown in FIGS. 3 and 4, the reed valve 22 is composed of a valve body 22a and a reed 22b. When the reed 22b bends toward the intake valve 12, an intake passage is opened and intake air passes through. On the other hand, even if a backflow, that is, a blowback of the intake air occurs, the reed 22b comes into close contact with the valve body 22a due to the pressure of the blowback and closes the opening, thereby preventing the intake air from flowing back.

It should be noted that the check valve is not limited to a fixed valve, and any type that has low suction resistance during forward flow may be used.

As explained above, according to this embodiment, the intake air is introduced into the combustion chamber 7 through the refueling valve 22 during low speed rotation, so that blowback of intake air does not occur, and filling during low speed rotation is prevented. Efficiency can be increased. In addition, during medium and high speed rotation, the intake air is introduced from the two intake bows (15.16), which reduces intake resistance and increases charging efficiency.
As a result, the charging efficiency can be increased over the entire operating range, and the engine output can be increased and the torque curve can be flattened. Furthermore, since blowback of intake air is prevented, a strong swirl of intake air from the intake port 16 is generated during low speed rotation, so that combustion can be improved.

FIG. 5 shows a second embodiment. That is, 2 for each cylinder.
two intake ports 15,16 and these intake ports H5,1
One intake valve 1 that simultaneously opens and closes two downstream opening ends of 6.
8 are provided, and one exhaust valve 25 and one exhaust port 26 are provided. An on-off valve 21 is attached to the intake port 15. The intake bow 6 is provided at a position offset from the center of the combustion chamber 27 so as to generate a strong swirl of passing intake air, and a glued valve 22 is installed as a check valve as in the first embodiment. .

The opening/closing valve 21 opens and closes in the same manner as in the first embodiment, and when the rotation speed is low, the intake air is transferred to the combustion chamber 27 via the fill valve 22.
be introduced within. Therefore, blowback of intake air is prevented,
Filling efficiency can be increased during low speed rotation.

Further, in this embodiment, the intake port 16 is formed to have a smaller cross-sectional area than the intake port 15, so that the intake flow rate of the intake port 16 is relatively small when the engine rotates at high speed.
This prevents the intake resistance of the reed valve 22 from increasing.

As described above, in this embodiment, as in the first embodiment, blowback of intake air during low-speed rotation can be prevented and charging efficiency can be increased, so that the output of the engine can be improved. In addition, according to the first and second embodiments, the blowback of intake air is improved, which makes it possible to use a high-speed camshaft with a larger overlap period compared to the conventional one, and from this point of view, the engine High output and flattening of the torque curve are achieved.

In addition, the above 1. Although the second embodiment has been described with reference to the same number of intake valves and exhaust valves, it is clear that the present invention is also applicable to a so-called three-valve intake system.

(Effects of the Invention) As explained above, according to the present invention, by providing a check valve in the intake port through which intake air passes when the engine rotates at low speed, the intake air is It is possible to improve filling efficiency by effectively preventing blowback.

Therefore, it is possible to improve engine output, fuel efficiency, exhaust characteristics, etc., and flatten the torque curve.

Furthermore, according to the present invention, blowback of intake air during low-speed rotation can be prevented, so it is possible to use a so-called high-speed camshaft with a long overlap period, and this also makes it possible to increase the output of the engine.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the first embodiment of the present invention, FIG. 2 is a configuration diagram showing the opening/closing mechanism of the on-off valve in the above, FIG. 3 is a perspective view showing the reed valve in the above, and FIG. A sectional view showing how the reed valve shown in Figure 3 is attached to the intake port;
FIG. 5 is a sectional view showing a second embodiment of the present invention, and FIG. 6 is a sectional view showing a conventional example. 11.12.18...Intake valve 15.16...Intake port 21...Opening/closing valve 22...Reed valve
22a...Valve body 22b...Lead patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio SasashimaFigure 3Figure 4Figure 5Figure 1a

Claims (1)

[Claims] In the intake system of an internal combustion engine, which has multiple intake ports for each cylinder, some intake ports are equipped with on-off valves that are controlled to close in the low speed range of the engine and open in the high speed range, and other intake ports are An intake system for an internal combustion engine, characterized in that it is equipped with a check valve that prevents backflow of the air.