JPS61205327A - Intake device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent an opening and closing valve from biting at the wall surface of a high speed use intake port when the valve receives an influence of its thermal expansion in high speed operation, by slidably mounting the opening and closing valve in the axial direction of a rotary shaft which controls the opening and closing valve in at least two cylinders to be simultaneously opened and closed. CONSTITUTION:A plane part 23 is formed in one portion of a rotary shaft 22, which controls an opening and closing valve 21 contained in a housing of at least two cylinders to be simultaneously opened and closed, and this plane part 23 mounts the opening and closing valve 21 of butterfly type by screws 27 through a spacer 24 having a cylindrical part 25 and a flange part 26. And the opening and closing valve 21, providing in two symmetrical positions long holes 28 from the peripheral surface toward the center, forms their width a little larger than the external diameter of the cylindrical part 25 in the spacer 24. While the opening and closing valve 21 forms its thickness slightly thinner than the length of the cylindrical part 25, further the plane part 23 of the rotary shaft 22 forms its length larger than the external diameter of the opening and closing valve 21. In this way, the opening and closing valve 21, being slidably mounted in the axial direction of the rotary shaft 22, attains the desired end.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a technique for improving the intake system of an internal combustion engine having two intake valves for each cylinder.

(Prior Art) An example of an intake system for this type of internal combustion engine is shown in FIG. 5 (see Japanese Patent Application No. 59-60918).

To explain this, the opening timing of the low-speed intake valve 1 and the high-speed intake valve 2 provided for each cylinder is changed, and the low-speed intake port 13 and the high-speed intake port 4 that communicate with each intake valve 1, 2 are changed. In addition, an on-off valve 6 is provided in the high-speed intake port 4, which is equipped with a high-speed intake valve 2 that has a large overlap with the exhaust valve 5. One intake throttle valve 8 is interposed in the intake passage 7 on the upstream side of '4.

In an operating range where the intake air flow rate is less than a predetermined value, the on-off valve 6 is fully closed to create a strong swirl inside the combustion chamber by utilizing the airflow flowing only from the low-speed intake port 3 along the peripheral wall of the combustion chamber. The company is trying to improve flammability by ordering

On the other hand, when the intake air flow rate exceeds a predetermined value, as the flow rate increases, that is, the rotational speed.

As the load increases, the opening degree of the on-off valve 6 is gradually increased to gradually increase the opening area of the high-speed intake port 4, and the on-off valve 6 is approximately fully opened in the maximum output range of the engine.
This aims to improve the intake air filling efficiency while suppressing an increase in the amount of unburned HC discharged immediately after the on-off valve 6 is opened.

By the way, in the above-mentioned device, when the on-off valve 6 is closed, the air pressure close to the atmospheric pressure on the upstream side of the intake throttle valve 8 is passed through the fresh air introduction passage 9 in which an orifice is inserted in the high-speed intake port 4 portion on the downstream side. Fresh air is inhaled between the time when the high-speed intake valve 2 closes and the time when it opens again, and the pressure difference between the high-speed intake valve 2 and the exhaust pressure is reduced, and the exhaust gas flows into the high-speed intake port 4 during the overlap period with the exhaust valve 5. This prevents the inflow of burned gas and significantly reduces the amount of burned gas that gets mixed into the air-fuel mixture, improving combustion performance.

(Problems to be Solved by the Invention) However, as described above, even in the case where the backflow of exhaust gas is prevented by introducing fresh air, as shown below,
However, there was room for improvement.

That is, in the configuration described above, since both the low-speed and high-speed intake ports 3.4 are provided downstream of the intake throttle valve 8, the upstream pressure of the on-off valve 6 becomes equal to the intake negative pressure during idling.

For this reason, when fresh air is introduced into the high-speed intake port 4 and the pressure inside the intake port 4 is increased to near atmospheric pressure, the differential pressure across the on-off valve 6 becomes large, causing problems with the sealing performance of the on-off valve 6. It's coming.

By the way, when the on-off valves 6 of a plurality of cylinders are controlled to open and close by the same rotating shaft 10, the following problem occurs when the sealing performance of the on-off valves 6 is improved.

Generally, the cylinder head is made of aluminum, and the housing of the on-off valve 6 is also preferably made of aluminum in order to reduce weight.

However, it is difficult to make the rotating shaft 10 sufficiently large in diameter (which creates resistance to air intake), and the rotating shaft 10 is made of aluminum because it has to be ground down to a flat surface in order to install the on-off valve 6 and holes for the mounting screws are formed. It is difficult to use steel in terms of strength, so it is necessary to use iron-based materials.

In this case, depending on the operating condition of the engine, the temperature of each component including the cylinder head may range from -20°C at the start in winter to around +130°C when running at high speed.
It varies in the range of around 0 degrees, and therefore each component is affected by the heat.

The coefficient of thermal expansion is about twice as different between iron and aluminum, and if the on-off valve 6 is attached to the rotating shaft 10 with almost no gap between it and the high-speed intake port 4 at room temperature, in the operating region where the temperature rises. At a certain high speed, the difference between the amount of expansion of the rotating shaft 10 in the axial direction due to thermal expansion and the amount of expansion of the housing of the on-off valve 6 in the same direction becomes large, and as a result, the on-off valve 6 touches the wall of the high-speed intake port 4. This causes the problem that the valve gets stuck and becomes unable to open, resulting in a reduction in engine output.

For this reason, it is necessary to provide a certain amount of clearance in advance between the on-off valve 6 and the wall of the high-speed intake port 4, which inevitably deteriorates the sealing performance.

If sufficient sealing performance is not achieved, the introduced fresh air will leak from the on-off valve 6 into the intake passage 7 on the upstream side, causing variations in the pressure in the high-speed intake port 4 of each cylinder. .

In this case, the proportion of residual gas differs for each cylinder, which may cause variations in combustion and unstable rotation.

The present invention was developed in view of these conventional problems, and solves the sealing problem while preventing the on-off valve from digging into the wall of the high-speed intake port even if it is affected by thermal expansion at high speeds. An object of the present invention is to provide an intake device for an internal combustion engine in which combustion performance during idling is improved as much as possible.

Means for Solving the Problems> For this reason, the present invention provides a method in which the on-off valves are attached to a rotating shaft that simultaneously controls the opening and closing of the on-off valves of two cylinders so as to be able to slide freely in the axial direction of the rotating shaft. The structure is as follows.

(Function) According to this configuration, the on-off valve can be slid in the axial direction of the rotating shaft.

<Example> The example shown in FIGS. 1 to 4 will be described below. still,
Elements that are the same as those in the conventional example are given the same reference numerals as in FIG. 5, and their explanation will be omitted.

A butterfly-type on-off valve 21 is formed on a flat surface 23 formed by cutting down a part of the rotating shaft 22 into a flat surface, which simultaneously controls the opening and closing of the on-off valves 21 housed in the housing 20 of at least two cylinders by a control device (not shown). is the cylindrical part 2
5 and a flange portion 26 via a spacer 24 with mounting screws 27 .

This on-off valve 21 has a long diameter 28 extending from the outer peripheral surface toward the center.
However, two points are located symmetrically with respect to the center of the on-off valve 21.
The width of this long length 28 is equal to the spacer 24.
The size is slightly larger than the outer diameter of the cylindrical portion 25.

Further, the thickness of the on-off valve 21 is the same as that of the cylindrical portion 2 of the spacer 24.
slightly thinner than the length of 5 (in this example, 0
．． 02 to 0.05 m), and the rotating shaft 22
The length of the flat portion 23 is larger than the outer diameter of the on-off valve 21, and is long enough to allow the on-off valve 21 to move sufficiently.

Here, the housing 20 is made of aluminum to reduce weight, and the rotating shaft 22 is made of iron to ensure strength.

According to this configuration, when the on-off valve 21 is attached to the rotating shaft 22, a gap is formed between the spacer 24 and the elongated part 28 of the on-off valve 21, which is large enough to allow sliding.
are formed at two locations, so rotation of the on-off valve 21 is restricted, and only movement in the axial direction of the rotating shaft 22 is possible.

Even if the mounting screw 27 is sufficiently tightened, the on-off valve 2
Since there is a gap Δh (approximately 0.02 to 0.05 m as described above) between 1 and the bottom surface of the flange portion 26 of the spacer 24, the movement of the on-off valve 21 in the axial direction of the rotating shaft 22 is There is no obstruction, and the on-off valve 21 does not rattle.

Therefore, at high speeds, which is an operating range where the temperature increases, the difference between the amount of expansion of the rotating shaft 22 in the axial direction due to thermal expansion and the amount of expansion of the housing 20 of the on-off valve 21 in the same direction becomes large, and the on-off valve 21 Even if the on-off valve 21 starts to hit the wall of the high-speed intake port 4, the on-off valve 21 is free to slide in the axial direction of the rotating shaft 22, so it can move according to the difference in the amount of elongation. This prevents the valve from digging into the wall, making it impossible to open the valve, and reducing engine output.

In addition, when only two on-off valves 21 are attached to the same rotating shaft 22, if one of the on-off valves 21 is allowed to slide freely as described above, the difference in the amount of elongation can be absorbed. .

<Effects of the Invention> As explained above, according to the present invention, the on-off valve is attached to the rotating shaft so that it can slide freely in the axial direction of the rotating shaft.
At high speeds, which is an operating range where the temperature rises, the difference between the amount of expansion in the axial direction of the rotating shaft due to thermal expansion and the amount of expansion in the same direction of the housing member of the on-off valve becomes large, and the on-off valve becomes attached to the high-speed intake port. Even if it starts to hit the wall, the on-off valve can slide freely in the axial direction of the rotating shaft, so it can move according to the difference in the amount of elongation. This has the effect that the output of the engine does not decrease due to the engine.

[Brief explanation of the drawing]

Fig. 1(A) is a plan view showing the on-off valve part in one embodiment of the present invention, Fig. 1(B) is a vertical cross-sectional view of the main part of Fig. 1(A), and Fig. 2 is the installed state of the on-off valve. FIG. 3 is an enlarged sectional view of the main part of FIG. 2. FIG. 4 is an overall schematic diagram of the above embodiment, and FIG. 5 is a plan sectional view showing a conventional intake system for an internal combustion engine.

Claims (1)

[Scope of Claims] For each cylinder, a high-speed intake port, a low-speed intake port, and the high-speed intake port are controlled to close at least in a low-speed range including idling and open and close in a high-speed range according to changes in operating conditions. In an intake system for an internal combustion engine, which is provided with a butterfly-type on-off valve and has a fresh air introduction passage that introduces fresh air close to atmospheric pressure to the downstream part of the on-off valve, the rotation control method simultaneously controls the opening and closing of the on-off valves of at least two cylinders. An intake device for an internal combustion engine, characterized in that the on-off valve is attached to a shaft so as to be slidable in the axial direction of the rotating shaft.