JPS5851375Y2 - 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.

Usually, particularly in gasoline engines, the intake port is formed in a port shape with small fluid resistance in order to increase charging efficiency during high-speed, high-load operation and thereby obtain sufficient output.

However, if such a port shape is used, during high-speed, high-load operation, a naturally occurring and quite strong turbulence will occur in the combustion chamber, so the combustion speed will be sufficiently increased, but during low-speed, low-load operation, sufficient turbulence will not occur within the combustion chamber. First, there is a problem that the combustion rate cannot be sufficiently increased.

There are ways to generate strong turbulence during low-speed, low-load operation by making the intake port a helical shape or by using a shroud valve to forcefully generate a swirling flow in the combustion chamber. There is a problem in that charging efficiency decreases during high-speed, high-load operation due to increased resistance.

Therefore, in order to increase the combustion rate during low-speed, low-load operation while ensuring high charging efficiency during high-speed, high-load operation, the intake port should be formed with a port shape that has low fluid resistance, and the combustion chamber should be closed during low-speed, low-load operation. must be controlled so as to generate a strong disturbance.

Furthermore, as a method of improving combustion during low-speed, low-load operation, in addition to generating strong turbulence within the combustion chamber, there is also a method of promoting vaporization of the fuel.

That is, during low-speed, low-load operation, the flow rate of air flowing through the venturi section of the carburetor is slow, and therefore the relative speed between the injected fuel and the air flow is slow, making it impossible to atomize the fuel sufficiently. A large amount of fuel is supplied into the combustion chamber in liquid form, which is one of the causes of worsening combustion and exhaust emissions.

In order to solve these problems, an internal combustion engine has been proposed in which an auxiliary intake passage is branched from the intake passage upstream of the carburetor throttle valve and opened again into the intake passage downstream of the carburetor throttle valve. There is.

In this internal combustion engine, when the engine is operated at low load with a small opening of the carburetor throttle valve, a large amount of air-fuel mixture is supplied into the combustion chamber through the sub-intake passage, which has a smaller cross-sectional area than the intake passage.

At this time, as described above, since the sub-intake passage has a small cross-sectional area, the air-fuel mixture flows at a high speed within the sub-intake passage, thus promoting vaporization of the fuel.

Furthermore, strong turbulence is generated within the combustion chamber due to the air-fuel mixture jetting out at high speed from the sub-intake passage.

However, in this internal combustion engine, most of the air-fuel mixture is supplied into the combustion chamber through the auxiliary intake passage during idle-link operation, and at this time, the negative pressure in the intake pipe is extremely large, so the flow velocity of the air-fuel mixture ejected from the auxiliary intake passage is low. becomes extremely fast.

As a result, there is a problem in that the turbulence generated in the combustion chamber during idle-link operation becomes too strong, which actually worsens combustion.

This invention is capable of generating strong turbulence in the combustion chamber when the engine is operating at low speed and low load while ensuring high charging efficiency during engine high speed and high load operation, and also prevents excessively strong turbulence from occurring within the combustion chamber during idling operation. The objective is to provide an internal combustion engine with improved performance.

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

Referring to FIGS. 1 and 2, 1 is an engine body, 2 is a cylinder block, 3 is a piston that reciprocates within the cylinder block 2, 4 is a cylinder head fixed on the cylinder block 2, and 5 is a piston 3 and the cylinder head 4, 6 is an intake port, I is an intake valve, 8
1 is an exhaust port, 9 is an exhaust valve, 10 is a spark plug, 11 is an intake manifold, 12 is a carburetor, 13 is a carburetor throttle valve, 14 is a carburetor main nozzle, and 15 is an exhaust manifold.

1 and 2, a distribution passage 16 extending in the longitudinal direction of the engine body 1 is formed between the outer wall surface of the cylinder head and the intake manifold 11, and is further provided in the cylinder head 4 with the intake port 6 of each cylinder. A distribution branch 17 is formed which communicates with the passage 16.

The openings 18 of these distribution branches 17 are oriented toward the gap formed between the intake valve and its valve seat when the intake valve is open, and these openings 18 are oriented toward the periphery of the combustion chamber 5 .

On the other hand, the central part of the distribution passage 16 is connected to an opening 21 opening into the mixture passage 20 upstream of the throttle valve 13 via an auxiliary intake passage 19. A valve 22 is provided.

The flow rate control valve 22 has a negative pressure chamber 24 and an atmospheric pressure chamber 25 separated by a diaphragm 23.
A compression spring 26 for pressing the diaphragm is inserted therein.

Further, a valve body 28 that controls opening and closing of the valve port 27 is connected to the diaphragm 23 .

On the other hand, when the throttle valve 13 is in the idle link position as shown in FIG.
3 opens into the upstream mixture passage 20 and opens into the throttle valve 13
When the valve opens, a negative pressure port 29 that opens into the mixture passage 20 downstream of the throttle valve 13 is formed, and the flow control valve 22
A negative pressure chamber 24 is connected to this negative pressure port 2 via a negative pressure conduit 30.
9.

On the other hand, a negative pressure diaphragm type EGR control valve 32 is provided in a recirculating exhaust gas (hereinafter referred to as EGR) supply conduit 31 that connects the inside of the exhaust manifold 15 and the inside of the intake manifold 11 .

This EGR control valve 32 has a negative pressure chamber 34 and an atmospheric pressure chamber 35 separated by a diaphragm 33.
A compression spring 36 for pressing the diaphragm is inserted into the spring 4 .

On the other hand, a valve element 38 for controlling opening and closing of a valve port 37 is connected to the die and diaphragm 33, and the negative pressure chamber 34 is connected to a negative pressure conduit 30 via a negative pressure conduit 39.

As shown in FIG. 2, when the throttle valve 13 is in the idling position, almost atmospheric pressure is applied to the negative pressure port 29.
Therefore, at this time, the inside of the dual pressure chamber 24.degree. 34 becomes approximately atmospheric pressure.

Therefore, at this time, both diaphragms 23 and 33 are moved toward the atmospheric pressure chamber 25 and 35 by the spring force of the compression springs 26 and 36, respectively, and each valve body 28 and 38 is moved to the corresponding valve port 21.
.

37 is closed, so that on the two sides the auxiliary intake passage 19 is blocked, so that the air-fuel mixture is supplied into the combustion chamber 5 via the intake manifold 11, and on the other hand, the EGR supply conduit 31 is blocked, so that the EGR Gas supply is cut off.

Next, when the throttle valve 13 is opened and low-load operation is performed, a large negative pressure acts in both the pressure chambers 24.34, so that both diaphragms 23.33 are affected by the spring force of the compression spring 26.36. The valve bodies 28, 38 move toward the negative pressure chambers 24, 34, respectively, against this, and thus both valve bodies 28, 38 open their corresponding valve ports 27, 37, respectively.

Therefore, at this time, on the one hand, the EGR supply conduit 31
R gas is supplied into the intake manifold 11, and on the other hand, a part of the air-fuel mixture formed in the carburetor 12 is fed into the intake ports of the cylinders under the intake stroke via the auxiliary intake passage 19 and the distribution passage 16. It ejects from the distribution branch 17.

As shown in FIGS. 1 and 2, the cross-sectional areas of the sub-intake passage 19, distribution passage 16, and distribution branch passage 17 are quite small;
Therefore, since the air-fuel mixture flows through these passages 19, 16, 17 at a high speed, the vaporization of the fuel in these passages 16, 17, 17 is greatly promoted.

Further, the air-fuel mixture is ejected from the distribution branch 17 into the intake port 6 at high speed, but as described above, the opening 1 of the distribution branch 17
8 is directed toward the gap formed between the intake valve 7 and its valve seat when the intake valve is opened, so the air-fuel mixture ejected from the distribution branch 1T flows at high velocity into the combustion chamber 5 through the gap,
In this way, a strong swirling flow as shown by arrow W in FIG. 1 is generated within the combustion chamber 5.

As a result, the combustion rate is greatly increased.

On the other hand, during high-load operation with a large opening degree of the throttle valve 13, the negative pressure applied to the negative pressure port 29 becomes extremely small.
is closed, and the supply of EGR gas is thus stopped.

At this time, the air-fuel mixture formed in the carburetor 12 is supplied into the combustion chamber 5 through the intake manifold 11 and the intake port 6, which have low fluid resistance, thereby ensuring high charging efficiency.

As described above, according to the present invention, the auxiliary intake passage is blocked during engine idling operation, so the turbulence generated in the combustion chamber is not excessively strong, thus ensuring good combustion.

In addition, since the supply of EGR gas is stopped during idle link operation, there is no need to create a large turbulence in the combustion chamber at this time, and in particular, the flow velocity of the air-fuel mixture flowing in the carburetor 12 is lower than during idle link operation. Therefore, when fuel vaporization is slow and not good, most of the fuel ejected from the main nozzle adheres to the throttle valve in a liquid state, and the air-fuel mixture supplied from the opening 21 into the sub-intake passage 19 is extremely diluted. It becomes.

Therefore, from these points of view, it is preferable to stop supplying the air-fuel mixture from the auxiliary intake passage into the combustion chamber during idle-link operation.

Further, since the negative pressure port 29 for controlling the flow rate control valve 22 and the EGR control valve 32 only needs to be provided on one side, manufacturing of the carburetor becomes easy.

On the other hand, during low-load operation when the throttle valve is open, the air-fuel mixture is supplied to the combustion chamber through the auxiliary intake passage, which can cause strong turbulence within the combustion chamber, and furthermore, during high-load operation, almost all of the air-fuel mixture is supplied into the combustion chamber through the intake manifold with low fluid resistance, ensuring high charging efficiency.

[Brief explanation of drawings]

Fig. 1 is a plan view of an internal combustion engine according to the present invention, and Fig. 2 is a plan view of an internal combustion engine according to the present invention.
FIG. 6...Temporary air port, T...Intake valve, 11
...Intake manifold, 12... Carburizer, 13... Throttle valve, 16... Distribution passage, 17... Division branch passage, 19 ...Sub-intake passage, 22...Flow rate control valve, 31...
- EGR supply conduit, 32...EGR control valve.

Claims (1)

[Scope of utility model registration request] Branching a sub-intake passage from the mixture passage upstream of the carburetor throttle valve and opening it again into the intake port downstream of the throttle valve, and interconnecting the exhaust manifold and the intake manifold by a recirculating exhaust gas supply conduit. In the internal combustion engine, a flow control valve that is provided with a negative pressure chamber and that closes when the negative pressure in the negative pressure chamber becomes larger than a predetermined negative pressure is arranged in the sub-intake passage, A recirculation exhaust gas control valve having a pressure chamber and closing when the negative pressure in the negative pressure chamber becomes larger than a predetermined negative pressure is provided in the recirculation exhaust gas supply conduit, and One negative pressure port is installed in the mixture passage, which opens into the mixture passage upstream of the throttle valve when the throttle valve is in the idle link position, and opens into the mixture passage downstream of the throttle valve when the throttle valve is opened. An intake device for an internal combustion engine, which is provided on a wall surface and connects a negative pressure chamber of the flow control valve and a negative pressure chamber of the recirculation exhaust gas control valve to the negative pressure port.