JPS5827058Y2 - Internal combustion engine intake system - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an intake system for an internal combustion engine.

In order to increase the combustion speed in the engine combustion chamber and thereby obtain stable combustion, the intake port is formed in a helical shape or a shroud valve is used to generate a strong swirling flow around the cylinder axis in the combustion chamber during the intake stroke. There are known ways to do this.

However, if the intake port is formed into a henocal shape or a shroud valve is used, flow resistance increases during high-speed, high-load operation with a large amount of intake air, resulting in a decrease in filling efficiency and the inability to obtain high output. There is a problem.

This invention is an internal combustion engine that can generate a strong swirling flow in the combustion chamber during low-speed, low-load operation with a small amount of intake air, while ensuring high charging efficiency during high-speed, high-load operation with a large amount of intake air. The purpose of the present invention is to provide an intake device for the following.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1 and FIG. 2, 1 is a cylinder block, 2 is a piston that reciprocates within the cylinder block 1,
3 is a cylinder head fixed on the cylinder block 1, 4 is a combustion chamber formed between the piston 2 and the cylinder head 3, 5 is an ignition plug, 6 is an exhaust valve, 7 is an exhaust passage, 8 is a main nozzle 9 The vaporizers are shown respectively.

Referring to FIG. 2, it can be seen that a pair of intake valves, a first intake valve 10 and a second intake valve 11, having the same shape are provided in the combustion chamber 4.

Furthermore, a first intake passage 12 connected to the combustion chamber 4 via the first intake valve 10 and a second intake passage 13 connected to the combustion chamber 4 via the second intake valve 11 are connected to the cylinder. The first intake passage 12 and the second intake passage 13 are assembled together in an intake manifold 14 and connected to a common carburetor 8 .

As shown in FIGS. 1 and 2, the first intake passage 1
2 is formed in a helical shape A near the back surface of the first intake valve 10, while the second intake passage 13 is formed in a substantially linear port shape with the smallest flow resistance.

Furthermore, a first throttle valve 15 is disposed at the outlet of the carburetor 8, and a second throttle valve 16 is disposed within the second intake passage 13.

As shown in FIG. 2, a model recess 17 is formed in the side wall of the intake manifold 14, and a valve shaft 18 of the second throttle valve 16 is disposed within this recess 17.

Therefore, as shown by the broken line in FIG. 2, when the second throttle valve 16 is fully opened, the second throttle valve 16 and the valve shaft 18 do not provide resistance to the air mixture flow. The flow resistance of the second intake passage 13 becomes extremely small.

The first throttle valve 15 is connected to an accelerator pedal on the driver's seat of the vehicle, and gradually opens depending on the amount of depression of the accelerator pedal.

The second throttle valve 16 may include, for example, a link mechanism (not shown).
is connected to the first throttle valve 15, whereby the second throttle valve 16 is held in a fully closed state when the first throttle valve 15 is below a predetermined opening degree, and the first throttle valve 1
5 becomes a predetermined opening or more, the second throttle valve 16 gradually opens, and when the first throttle valve 15 is fully opened, the second throttle valve 16 opens gradually.
The throttle valve 16 is also controlled to be fully open.

However, when the second throttle valve 16 is connected to a negative pressure diaphragm device that responds to the negative pressure generated in the venturi section B of the carburetor 8, when the negative pressure generated in the venturi section B becomes larger than a predetermined negative pressure, The second throttle valve 16 may be opened.

During low-speed, low-load operation with a small amount of intake air, the second throttle valve 16 is kept fully closed, so the air-fuel mixture formed in the carburetor 8 flows only through the first intake passage 12 into the combustion chamber 4.
flow inside.

At this time, since the first intake passage 12 is formed in the rectangular shape A as described above, the air-fuel mixture flowing into the combustion chamber 4 generates a swirling flow around the cylinder axis indicated by the arrow W.

In the present invention, the ignition plug 5 is connected to the first intake valve 1 as shown in FIG.
0 and the exhaust valve 6 at the periphery of the combustion chamber 4.

By arranging the spark plug 5 at the periphery of the combustion chamber 4 in this manner, the electrode of the spark plug 5 is exposed to a strong swirling air mixture flow, whereby the electrode of the spark plug 5 is effectively scavenged.

The swirling air-fuel mixture within the combustion chamber 4 is then ignited by the spark plug 5.

Regarding the propagation of flame in a swirling mixture flow, it is known that the propagation speed of flame from the periphery of the swirling flow toward the center of swirling is faster than the propagation speed of flame from the center of swirling toward the periphery of the swirling flow.

Therefore, by arranging the spark plug 5 at the periphery of the combustion chamber 4, the combustion speed can be greatly accelerated, and stable combustion can thus be obtained.

In order to effectively scavenge the electrode of the spark plug 5 and obtain a sufficiently high combustion rate, it is preferable to set the distance r from the cylinder center axis to the spark plug 5 to be greater than or equal to the radius R of the cylinder.

During high-speed, high-load operation with a large amount of intake air, the second throttle valve 16 is fully opened, so the air-fuel mixture formed in the carburetor passes through both the first intake passage 12 and the second intake passage 13 into the combustion chamber. 4.

In this way, during high-speed, high-load operation, the cross-sectional area of the air-fuel mixture flow path becomes significantly large, and since the second throttle valve 16 is retracted into the recess 17, the flow resistance in the second intake passage 13 becomes extremely small. In this way, high filling efficiency can be ensured.

Normally, when installing intake and exhaust valves in a vent roof type or hemispherical combustion chamber, the diameter of the intake valve is usually 0.48D to 0.50D when the diameter of the cylinder is D. range, the diameter of the exhaust valve is selected to be in the range of 0.41D to 0.43D, while the intake and exhaust valves are each
When installing two valves, the diameter of the intake valve is usually from 0.35D to 0.
．． 37D range, exhaust valve diameter from 0.28D to 0.3
2D range (Designer's
View Point IMEReport C34
3/73 H, W, Barnes-Moss).

The diameters of the intake and exhaust valves are selected to allow for convenient placement of the intake and exhaust valves within the combustion chamber and to maximize the area of the flow path formed between the intake and exhaust valves and their valve seats.

When two intake valves and one exhaust valve are provided as in the present invention, the diameter of the exhaust valve is within the normal value range of 0.
41D to 0.44D, and the diameter of the intake valve was set to 0.44D.
It has been found that a selection in the range 38D to 0.42D is optimal.

As described above, when the second throttle valve 16 is connected to the first throttle valve 15 via the link mechanism, the second throttle valve 16 is opened when the engine load exceeds a predetermined load.
However, when the second throttle valve 16 is controlled to open in response to the negative pressure generated in the carburetor venturi section B, the second throttle valve 16 opens at high speeds when the amount of intake air exceeds a predetermined amount. The valve will open during load operation.

In addition, as an intake swirl flow generating mechanism for generating an intake swirl flow in the combustion chamber 4 during the intake stroke, an intake valve such as a shroud valve is used instead of the recal type intake port shown in Figures 1 and 2. You can also do that.

Further, the opening/closing timing of the first intake valve 10 and the second intake valve 11 can be completely synchronized, or the opening timing of the second intake valve 11 can be made earlier than the opening timing of the first intake valve 10. can.

As described above, according to the present invention, high charging efficiency can be obtained during high-load operation, so high output can be obtained.On the other hand, during low-load operation, a strong swirling flow is generated in the combustion chamber, so the combustion speed is low. thus, stable low-load operation can be ensured.

[Brief explanation of drawings]

1 is a side cross-sectional view of an internal combustion engine according to the present invention taken along the line I--T in FIG. 2, and FIG. 2 is a cross-sectional view taken along the line ■--■ in FIG. 4... Combustion chamber, 6... Exhaust valve, 10.
...First intake valve, 11...Second intake valve,
12...First intake passage, 13...Second
Intake passage, 15...First throttle valve, 16.
...Second throttle valve.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine in which an engine combustion chamber is provided with a first intake valve and a second intake valve, the intake passage downstream of the first throttle valve for engine load control is divided into two into a first intake passage and a second intake passage; An intake passage is connected to the combustion chamber via a first intake valve, and a swirl flow generation mechanism is provided in the first intake passage,
The second intake passage is connected to the combustion chamber via a second intake valve, and the second intake passage is formed in a substantially straight shape with low flow resistance. An intake system for an internal combustion engine, wherein a two-throttle valve is provided, and the valve shaft of the second throttle valve is arranged on the L side wall surface of a second intake passage, so that the second throttle is fully opened when a high intake air amount is obtained.