JPS6343385Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an intake system for an internal combustion engine that allows effective combustion to be obtained at all times regardless of the operating state of the engine.

In general, a direct injection diesel engine differs from a gasoline engine in which fuel is mixed with air in a carburetor before being introduced into a combustion chamber, or a pre-combustion chamber type diesel engine in which the above mixing is performed in a pre-combustion chamber. The fuel and air meet for the first time at , and mixing must take place within a very short period of time. Therefore, the quality of the mixture of fuel and air directly affects the combustion state, and the performance of the engine, such as output, torque, and
It affects the smoke etc.

One of the factors directly related to the quality of this mixture is
The other is the fuel injection action of the injection valve, and the other is the flow of the intake air, that is, the swirl of the intake air around the axis of the combustion chamber (hereinafter referred to as swirl).

In order to obtain the above-mentioned swirl, various intake devices have been proposed in the past, and FIGS. 1a and 1b show a helical port that is a typical device.
In the figure, inside the cylinder head 1, there is a dome part or spiral part 2 that communicates with a combustion chamber (not shown).
The dome part 2 is formed with a port part 4 that is connected in a helical shape through a throat part, that is, a protrusion part 3, and the intake manifold 5 is connected to the helical port part 4 and the throat part 3. When the fuel flows into the combustion chamber, it generates a swirl as shown by the chain arrow.

By the way, the strength of the swirl depends on the speed at which the intake air passes through the port section 4, and the strength of the swirl is usually adjusted optimally when the engine speed is in the medium speed range, in which case good combustion can be obtained. However, at high speeds, the swirl is too strong and the atomized fuel overlaps, and at low speeds the swirl is too weak, making it impossible to achieve optimal combustion at high speeds and low speeds.

In order to solve the above problem, for example,
As shown in Publication No. 54007, the port section 4
is formed into two ports, an upper port and a lower port, and a swirl control plate that can be opened and closed is provided on the inlet side of the upper port to change the intake air inflow speed and direction according to the engine speed to achieve optimal combustion. It is known what made it possible to do so. However, in all of these prior art techniques, swirl control is not sufficient, and even if swirl can be controlled, the control mechanism is complicated.

For example, Japanese Utility Model Application Publication No. 57-13834 discloses a technique in which a variable plate is moved by the air flow velocity in order to increase the swirl in a low-speed operating range and to weaken the swirl in a high-speed operating range. However, operating the variable plate solely by the air flow rate is unstable, making control difficult and unable to perform suitable control.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an intake system for an internal combustion engine that can obtain an optimum swirl with a simple control device regardless of the operating state of the engine.

According to the present invention, there is provided an intake system for an internal combustion engine in which a dome portion communicating with a combustion chamber is formed inside a cylinder head, and a port portion helically connected to the dome portion via a throat portion. A swirl guide groove is formed along a part of the wall surface of the port section and communicates the intake manifold attached to the cylinder head with the dome section. A guide plate is provided which can expand or contract the opening area of the swirl guide groove on the dome side, and the guide plate is controlled in its forward and backward movement by an actuator attached to the intake manifold.

Therefore, the guide plate is moved back and forth by the actuation of the actuator, but it is sufficient to move the guide plate back and forth by setting the input signal of the actuator (for example, the supply of air to an air cylinder) according to the rotational speed of the engine. Therefore, when the engine speed is low, the guide plate reduces the opening area of the swirl guide groove, increasing the speed of the intake air flow and increasing the swirl. Conversely, when the engine speed is high, the intake airflow is decelerated and the swirl is weakened.
Swirl control is therefore reliable, so that an effective dome is obtained regardless of the engine speed.

In addition, since the guide plate is controlled in its forward and backward movement by an actuator such as an air cylinder attached to the intake manifold, when applying the present invention to a conventional engine, it is only necessary to slightly modify the intake manifold, and it is not necessary to modify the intake manifold. Easy to improve.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 2 and 3. In these drawings, all parts corresponding to those in FIG. 1 are designated by the same reference numerals.

In FIG. 2, a swirl guide groove 6 is formed along the convex side wall 4b of the port section 4 to communicate the intake manifold 5 and the dome section 2, and the groove 6 forms a part of the convex side wall 4b. It is covered by a guide plate 7.

On the other hand, an air cylinder 8 is attached to the outside of the intake manifold 5, and a rod 11 is attached to a piston 10 housed inside the air cylinder 8 and urged toward the contraction side by a spring 9.
protrudes into the intake manifold 5, and its tip is fixed to the end of the guide plate 7. This air cylinder 8 can expand or contract the opening area of the swirl guide groove 6 on the dome side by moving the guide plate 7 back and forth with the rod 11 via the piston 10 by supplying air controlled according to the engine speed. It's becoming like that. Air supply may be determined based not only on the engine speed but also on the load.

Next, the effect will be explained.

When the engine speed is low, a large amount of air is supplied to the air cylinder 8, which presses the piston 1.
0 connects the guide plate 7 to the second via the rod 11.
It is advanced as shown in Figure a, and the opening area of the swirl guide groove 6 on the dome side is reduced to almost zero. As a result, the intake air flow flows only through the port portion 4 as shown by the arrow, resulting in a high flow velocity, resulting in a strong swirl.

When the engine speed increases, the amount of air supplied decreases accordingly, and the piston 10 is urged by the spring 9 and moves toward the contraction side, thereby causing the guide plate 7 to move backward as shown in FIG. 2b. be done. Then, the opening area of the swirl guide groove 6 is enlarged as shown in the figure, and the amount of intake air flows through both the port portion 4 and the swirl guide groove 6, as shown by the two arrows, near the opening of the swirl guide groove 6. The air flow is canceled out and the flow velocity is therefore reduced, resulting in
Swirl is weakened.

In this way, when the engine speed is low, the opening area of the swirl guide groove 6 is reduced, so that the intake air flow is not obstructed, and as a result, a strong swirl is obtained, while at high speeds, the opening area is expanded,
This slows down the intake airflow and, as a result, reduces the swirl, thereby ensuring effective combustion at all times regardless of engine operating conditions. Further, since the guide plate 7 and the air cylinder 8 can be attached to the intake manifold 5, the structure is simplified.

FIG. 3 shows another embodiment of the present invention, in which a swirl guide groove 6 is provided in the concave side wall 4a of the port portion 4. This embodiment also has the same effects as in FIG. 2.

[Brief explanation of drawings]

FIG. 1 shows a conventional device, FIG. 1a is a side sectional view, FIG. 1b is a cross-sectional view, and FIGS.
is a cross-sectional view at low speed, b is a cross-sectional view at high speed, and c is A- of a.
It is a sectional view taken along the line A. 2... Dome, 3... Throat, 4... Port, 5... Intake manifold, 6... Swirl guide groove, 7... Guide plate, 8... Air cylinder, 11... Rod.

Claims (1)

[Scope of utility model registration request] In an intake system for an internal combustion engine, in which a dome portion communicating with a combustion chamber and a port portion helically connected to the dome portion via a throat portion are formed inside a cylinder head, a wall surface of the port portion is formed. A swirl guide groove is formed along a part of the cylinder head and has a concave portion that communicates the intake manifold attached to the cylinder head with the dome portion. 1. An intake system for an internal combustion engine, characterized in that a guide plate is provided that can expand or contract an opening area on the side of a dome part, and the guide plate is controlled to move back and forth by an actuator attached to an intake manifold.