JPH028127B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a spark ignition internal combustion engine, in which a sub-intake port is opened in an intake port to a combustion chamber, and a mixture is added from the sub-intake port. This invention relates to an internal combustion engine in which a strong swirl is generated within the combustion chamber by supplying pressure, thereby increasing the flame propagation speed and improving combustibility.

[Problems to be solved by conventional technology and invention]

Generally, it is known that in order to improve the ignition and combustibility of the intake air-fuel mixture in the combustion chamber, it is sufficient to increase the flow velocity of the intake air-fuel mixture in the combustion chamber. The flow velocity is high, the flame propagation velocity is high, and combustion is stable.However, in the low load/low rotation range, the flow velocity of the intake air-fuel mixture is slow, the flame propagation velocity is low, and combustion becomes unstable.

Therefore, as a prior art related to preventing this, for example, as described in Japanese Utility Model Application Publication No. 53-32217, air is supplied from another auxiliary intake port to the combustion chamber or intake port. Alternatively, it has been proposed to accelerate the flow rate of the intake air-fuel mixture and enhance the filling effect by supplying the air-fuel mixture under pressure.

However, among the prior art proposed here, those that supply air under pressure, such as the former,
Pressurized supply of air only has the meaning of increasing the flow velocity of the intake mixture, and pressurized supply of air tends to make the air-fuel ratio of the mixture in the combustion chamber unstable, so it is extremely light. The effect can only be obtained in a very narrow load operating range, and it is not possible to sufficiently improve ignition and combustibility in low load and low rotation ranges. Not only is a fuel supply means such as a separate carburetor required to form a pressurized air-fuel mixture, but it is also necessary to pressurize the air-fuel mixture to eliminate fluctuations in the total air-fuel ratio in the combustion chamber. In some cases, it is necessary to provide a fuel adjustment means to control the amount of fuel supplied from the intake port to the intake air-fuel mixture by the amount of fuel added to form the pressurized air-fuel mixture, so the structure is extremely complicated. It was hot because it became .

According to the present invention, when a dual downdraft type carburetor is used in the intake system of an internal combustion engine, liquid fuel or a relatively rich air-fuel mixture is present near the inner bottom surface of the collecting part where the carburetor is attached. The object of the present invention is to take advantage of this fact to provide a spark ignition internal combustion engine that solves the problems of the prior art.

[Means to solve the problem]

To achieve this object, the present invention provides an internal combustion engine in which the collecting part of the intake manifold attached to the side surface of the cylinder head faces upward, and a downdraft type carburetor is attached to the upper end of the collecting part of the intake manifold. The cylinder head is provided with a sub-intake port that opens into the intake port to the combustion chamber, and the sub-intake port is connected to the air compressor. The combustion chamber is connected to a discharge port of the combustion chamber, and furthermore, the opening of the sub-intake port into the intake port is oriented in a direction that produces a swirl within the combustion chamber.

[Action/effect of the invention]

With this configuration, the liquid fuel and rich air-fuel mixture that gather in a large amount in the area directly below the downdraft type carburetor are extracted by the air compressor and compressed to form a rich supercharged air-fuel mixture. can be injected from the auxiliary intake port into the intake port in a direction that creates a swirl in the combustion chamber, which can significantly promote ignition and combustion in the low load and low rotation range of the internal combustion engine. It is possible to improve the output of the engine and improve the fuel efficiency.

On the other hand, by extracting the liquid fuel and rich air-fuel mixture that gathers in the area directly below the downdraft type carburetor using an air compressor and creating a rich pressurized air-fuel mixture, this is supplied from the sub-intake port. , there is no need to provide a separate fuel supply means for forming a pressurized mixture, and since the pressurized mixture is supplied to the intake port, there is no fluctuation in the total air-fuel ratio in the combustion chamber, and the air-fuel mixture is Since the fuel ratio can be stabilized and there is no need for fuel adjustment means for the intake air-fuel mixture from the intake port to the combustion chamber as in the prior art described above, the structure is extremely simple and has the effect of being miniaturized. It is.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 indicates a cylinder block 2,
An internal combustion engine is shown having a cylinder head 3, a piston 4, a combustion chamber 5, an intake port 6 with an intake valve 7, an exhaust port 8 with an exhaust valve 9, and a spark plug 10. An intake manifold 11 connected to the intake manifold 11 is attached to the upper end of the upward gathering portion 12 of the intake manifold 11, and a conventionally known two-barrel downdraft type carburetor 13 is attached to the upper end of the upward gathering portion 12.

This downdraft type carburetor 13 is equipped with a secondary side carburetor 14 on the side closer to the cylinder head 3 and a primary side carburetor 15 on the far side, and the throttle valve 16 of the secondary side carburetor 14 is connected to the primary side carburetor 14. The throttle valve 17 of the side carburetor 15 starts to open when it is fully open or close to fully open, and the primary side carburetor 15 of the carburetor 13 is provided on the inner bottom surface of the gathering portion 12 in the intake manifold 11. A recess 18 is provided at a portion substantially directly below. Note that this recess 18 is not necessarily necessary, and may be provided when it is desired to collect liquid fuel more actively in a low load/low rotation range to further enhance the swirl effect.

Reference numeral 19 denotes an air compressor that is attached to an appropriate location such as the lower surface of the intake manifold 11. The air compressor 19 is preferably a positive displacement type such as Roots, a movable blade, or a reciprocating type, but a centrifugal type air compressor is also preferable. Alternatively, power transmission from the internal combustion engine 1 or internal combustion engine 1 may be performed.
The engine is rotated by an exhaust gas turbine that utilizes exhaust gas energy, an electric motor, or the like.

And, the intake port 20 of this air compressor 19,
The cylinder head 3 is connected to the recess 18 in the inner bottom surface of the gathering part 12 of the intake manifold 11 through a passage 21, while a sub-intake port 22 is bored into the intake port 6 in the cylinder head 3. , the air compressor 1 is connected to the inlet end of the sub-intake port 22.
Furthermore, the opening of the sub-intake port 22 into the intake port 6 is connected to the intake valve 7.
The combustion chamber 5 is oriented in such a direction that a swirl is generated in the combustion chamber 5 at approximately the rear side of the combustion chamber 5. That is, the opening of the sub-intake port 22 into the intake port 6 is connected to the intake port 6 and the combustion chamber 5.
In other words, the air-fuel mixture ejected from the sub-intake port 22 causes the air-fuel mixture to flow into the intake port 6.
It is also oriented in the direction of giving a swirling flow to the air-fuel mixture inside and in the combustion chamber 5. Note that if the scavenging effect around the spark plug 10 is also improved, the opening of the sub-intake port 22 into the intake port 6 should be
It may also be directed toward the vicinity of 0.

Note that reference numeral 24 in FIG. 2 has inset portions 27 and 28 inside the circular contour 26 of the cylinder bore 25 between the intake valve 7 and the exhaust valve 9 and between the intake valve 7 and the spark plug 10. Indicates the stock area.

In this configuration, in the low load/low rotation range of the internal combustion engine 1, air is taken only from the primary carburetor 15 side of the carburetor 13, and in this state,
Because the intake air flow rate is slow and fuel atomization is poor,
A considerable amount of the fuel, in a liquid state without being atomized, will collect on the inner bottom surface of the collecting section 12 approximately directly below the primary carburetor 15, and this collecting section 1
The fuel and rich air-fuel mixture that have gathered on the inner bottom surface of the intake port 6 are sucked into the air compressor 19 and pressurized, so that the fuel is almost completely atomized and
The air-fuel mixture is richer than the air-fuel mixture that reaches the combustion chamber 5 from the combustion chamber 5, and this rich pressurized air-fuel mixture is ejected from the sub-intake port 22 into the intake port 6.

In this way, from the sub-intake port 22 to the intake port 6
The rich pressurized air-fuel mixture that is injected into the combustion chamber 5 accelerates the flow velocity of the intake air-fuel mixture in the combustion chamber 5 and increases the flame propagation speed. At the same time, the residual gas around the ignition plug 10 is blown away and the scavenging air around the ignition plug 10 is completely completed, and at the same time, a rich air-fuel mixture is supplied to the vicinity of the ignition plug, forming a so-called stratified supply air. The amount of fuel and rich air-fuel mixture that collects on the inner bottom surface of the section 12 increases as the rotational speed of the internal combustion engine 1 decreases, so the stratified air supply can be reliably achieved in the low rotational speed range of the internal combustion engine 1, so that the ignition of the fuel and rich mixture increases. In addition to significantly improving the flame propagation speed within the combustion chamber, combustion can be stabilized.

In addition, when the internal combustion engine 1 is under high load such that air is taken not only from the primary side carburetor 17 in the carburetor 13 but also from the secondary side carburetor 18,
Even in a high-speed operating range, if the air-fuel mixture is supplied under pressure from the auxiliary intake port 22, the flame propagation speed within the combustion chamber can be further increased and combustion can be further stabilized. Furthermore, in such high load and high rotation ranges, the flow velocity of intake air increases, improving fuel atomization, and the flow velocity within the combustion chamber also increases, improving ignition and combustibility. Machine 1
9 is provided with a power cut-off means (not shown) such as an electromagnetic clutch at its input part to operate in an operating range where pressurized supply of air-fuel mixture from the auxiliary intake port 22 is unnecessary, that is,
It is also possible to configure the rotary drive of the air compressor 19 to be stopped by the above-mentioned power cutoff means when the load and rotation speed are high.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of a main part of an internal combustion engine, and FIG. 2 is an enlarged bottom view of FIG. 1. 1...Internal combustion engine, 3...Cylinder head, 5...
...Combustion chamber, 6...Intake port, 7...Intake valve, 1
0... Spark plug, 11... Intake manifold, 12
...Gathering part, 13...Dual down draft type carburetor, 14...Secondary side carburetor, 15...
...Primary side carburetor, 19...Air compressor,
22...Sub-intake port.

Claims (1)

[Claims] 1. In an internal combustion engine in which the collecting part of the intake manifold attached to the side surface of the cylinder head faces upward and a downdraft type carburetor is attached to the upper end thereof, the vicinity of the inner bottom surface of the collecting part of the intake manifold and the air compression The cylinder head is connected to the intake port of the engine, and the cylinder head is provided with a sub-intake port that opens into the intake port to the combustion chamber,
A discharge port of the air compressor is connected to the auxiliary intake port, and an opening of the auxiliary intake port into the intake port is oriented in a direction that generates a swirl within the combustion chamber. A spark ignition internal combustion engine characterized by the following configuration.