JPS628627B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims at increasing the combustion rate of a gasoline engine to improve output and make exhaust gas cleaner.

In a gasoline engine, the inner diameter of the intake port that guides the air-fuel mixture into the combustion chamber is set so that sufficient output can be obtained in the engine's high load and high rotation range. Lean burn cannot be achieved as it is, since the flow velocity within the combustion chamber is low and the combustion velocity cannot be increased due to the slow flow velocity within the combustion chamber.

Therefore, recently, as described in Japanese Patent Application Laid-Open No. 55-101725, etc., the intake ports of multiple cylinders of a multi-cylinder internal combustion engine are connected with each other by a jet communication passage, and when the intake air is drawn into one cylinder, The air-fuel mixture in the intake ports of other cylinders is guided and ejected into the intake port of the relevant cylinder via the jet flow passage, thereby accelerating the flow rate of the air-fuel mixture into the combustion chamber and promoting the combustion speed. A so-called intake jet type internal combustion engine has been proposed.

However, even in this type of engine, in order to reduce NOx in the exhaust gas in order to make the exhaust gas cleaner, it is necessary to recirculate a part of the exhaust gas to the intake system. In jet type internal combustion engines, the exhaust gas recirculation passage to the intake system is connected to the jet flow communication passage together with the slow system fuel passage in the idling or low load range, which causes the following problems. .

That is, connecting the slow system fuel passage and the exhaust gas recirculation passage to the jet communication passage in this way means that the exhaust gas that is recirculated to the intake system enters the jet communication passage cooled by the slow system fuel. Not only does the moisture in the exhaust gas condense and corrode the inner wall surface of the jet communication passage, but also the carbon in the exhaust gas often adheres to the inner wall surface of the jet communication passage, causing damage to the jet communication passage. Since the area is reduced and the amount of exhaust gas recirculated decreases, the air-fuel ratio of the intake air-fuel mixture during exhaust gas recirculation will change from the set value, and furthermore, due to the flow of recirculated exhaust gas in the jet communication passage, Fuel is sucked out of the slow system fuel passage, which also causes changes in the air-fuel ratio. Such a change in the air-fuel ratio of the intake air-fuel mixture not only greatly affects the performance of the engine, but also increases the amount of harmful gases in the exhaust gas.

The present invention aims to solve this problem and to further improve the effect of the intake jet by recirculating the exhaust gas to the intake system.

For this reason, the present invention connects one carburetor to the intake ports of a plurality of cylinders in a multi-cylinder internal combustion engine via a throttle passage provided with a throttle valve corresponding to each intake port. The respective intake ports of the cylinder are connected to each other via a jet flow communication passage which guides and blows out the air-fuel mixture in the intake port of the other cylinder to the intake port of the cylinder when the cylinder takes air. In the internal combustion engine, a balance passage is provided independently of the jet flow communication passage, the balance passage communicating between each of the throttle passages or between each intake port on the downstream side of the throttle valve, and in the balance passage, A slow system fuel passage from the carburetor is connected, and an exhaust gas recirculation passage for the intake system is connected to the jet flow communication passage, and a pressure chamber is normally biased closed by a spring in the exhaust gas recirculation passage. A reflux control valve is provided that opens against the spring when negative pressure is applied to the reflux control valve, and a pressure chamber in the reflux control valve is connected to a sensing port provided at a location upstream of the closed position of the throttle valve. The exhaust gas recirculation passage is connected to the exhaust gas recirculation passage, and is connected to the exhaust gas recirculation passage in conjunction with the throttle valve so that the throttle valve starts opening after reaching a certain opening degree and becomes fully open before the throttle valve is fully open. This configuration includes a sub-recirculation control valve.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, reference numeral 1 indicates the first cylinder A1 and the second cylinder A1.
It shows a 2-cylinder 4-stroke engine with cylinder A2,
The cylinder head 3 attached to the top surface of the cylinder block 2 has intake ports 4, 4' with intake valves 5, 5' for intake of air-fuel mixture into the combustion chamber of each cylinder, and intake ports 4, 4' with intake valves 5, 5' for discharging exhaust gas. Exhaust ports 6 and 6' with exhaust valves 7 and 7' are provided, respectively, and an exhaust passage 8 is connected to both exhaust ports 6 and 6'.

Reference numeral 9 in the figure indicates a variable ventilee type carburetor, and the variable ventilee type carburetor 9 has a piston-shaped sliding body 10, a float chamber 11, a main nozzle 12 and a main The piston-shaped sliding body 1 consists of a needle valve 13 and the like attached to the sliding body 10 so as to fit into the nozzle 12.
The carburetor 9 moves up and down in response to the negative pressure in the ventilate section 14 directly below it so that the negative pressure remains approximately constant. 16
and a slow system fuel passage 17.

Reference numeral 18 in the figure is a throttle body interposed between the carburetor 9 and the side surface 2' of the cylinder head where each of the intake ports 4, 4' opens. Throttle passages 19, 19' each having a throttle valve 20, 20' are provided corresponding to both intake ports 4, 4' to guide the air-fuel mixture to both intake ports 4, 4'. ing. Both the throttle valves 20, 20' are attached to one shaft 21,
The throttle body 18 is opened and closed at the same time by a lever 22, and the joint surface of the throttle body 18 to the cylinder head 2 is formed with an appropriate shape, such as a rectangular cross section, in order to communicate the two throttle passages 19, 19' with each other. A balance passage 23 is carved,
The throttle body 18 has both throttle passages 1
A port 24 communicating with the balance passage 23 is bored in a region between 9 and 19', and the slow system fuel passage 17 in the carburetor 9 is connected thereto, and the opening area of the port 24 is adjusted. An idle adjustment screw 25 is provided for this purpose.

Note that the balance passage 23 may be provided in the intake port portion instead of the throttle body 18, and the cross-sectional area of the balance passage 23 is such that the cross-sectional area of the balance passage 23 is such that the pistons are separated from each other with a phase difference of 360° as in a four-stroke two-cylinder internal combustion engine. For those that move up and down at the same time,
Since the pulsations in both ports are large, it is desirable to minimize the inside of the balance passage 23 to the extent that the fuel can flow without any trouble, taking into consideration the uniformity of fuel distribution.

Further, reference numeral 26 in the figure indicates a jet communication passage carved in the side surface 2' of the cylinder head 2 where both intake ports 4, 4' open. port 4,
Jet holes 27, 27' are bored toward the inside of the intake valve 4', and the openings of the jet holes 27, 27' into the intake port are tangential to the intake port at approximately the back surface of the intake valve. , in other words, the jet holes 27,2
By the jet flow from 7' into the intake ports 4, 4',
It is oriented in a direction that can give a swirling flow to the air-fuel mixture in the intake port.

Furthermore, reference numeral 28 in the figure is a diaphragm pressure-operated exhaust gas recirculation control valve, the inlet of the recirculation control valve 28 is connected to the exhaust passage 8 via the exhaust gas recirculation passage 29, and the outlet is connected to the sub-recirculation control valve. The valve bodies 32 of the recirculation control valves 28 are connected to the jet flow communication passages 26 via exhaust gas recirculation passages 31 with valves 30, and the valve bodies 32 of the recirculation control valves 28 are biased in the normally closed direction by the springs 34 in the pressure chambers 33, and , a pressure chamber 33 is provided in a sensing port 35 in the throttle body 18 at a location appropriately upstream from the closed position (idle opening) of one of the throttle valves 20';
When the negative pressure in the sensing port 35 is large, the valve body 32 of the recirculation control valve 28 is connected via the negative pressure extraction passage 36 so as to open against the spring 34 .

Note that the spring 34 in the reflux control valve 28
If the throttle valve is near the idle position or
The valve body 32 closes only near the fully open position,
The valve body 32 is set to be open at other throttle opening positions.

A torsion spring (not shown) is provided on the valve shaft 37 of the sub-reflux control valve 30 to normally close the valve, while the trochanter 39 at the tip of the lever 38 fixed to the valve shaft 37 is Throttle valve 2
The cam plate 40 fixed to the valve shaft 21 of the cam plate 40 is configured to open the sub-reflux control valve 30 in conjunction with the opening of the throttle valves 20 and 20'. Depending on the shape, the opening degree of the sub-control valve 30 relative to the opening degree of the throttle valve, for example, as shown by curve B in FIG. The sub-recirculation control valve 30 is configured to be fully opened before the throttle valve 20 is fully opened.

In this configuration, when the engine is operated, for example, when the first cylinder A1 is in the intake stroke, its intake valve 5 is open and the intake negative pressure is large, while the intake valve 5' in the second cylinder A2 is closed and the intake negative pressure is high. Since a small but large pressure difference occurs between the first cylinder intake port 4 and the second cylinder intake port 4', the air-fuel mixture entering the second cylinder intake port 4' flows through the jet hole due to the pressure difference. 27' and the jet flow communication passage 26, and is ejected from the jet hole 27 into the intake port 4 of the first cylinder A1 during the intake stroke, and this jet flow accelerates the intake air mixture flow from the intake port 4 to the combustion chamber. At the same time, a swirling flow is provided and the combustion speed is accelerated because the fluid flows violently within the combustion chamber.In addition, during the intake stroke of the second cylinder,
By jetting the air-fuel mixture in the first cylinder intake port 4 from the jet hole 27' into the second cylinder intake port 4', the combustion speed in the second cylinder can be similarly promoted. In this case, both throttle valves 20, 2
The smaller the opening degree of 0', the larger the pressure difference between both intake ports 4, 4', and the stronger the jet flow, so the effect of promoting the combustion speed by the jet flow becomes stronger as the engine load becomes lower. As it grows, lean burn becomes possible.

Then, in the idling or low load range where the throttle valves 20, 20' open to the sensing port 35, and in the full load range where the throttle valve is fully open or close to fully open, the sensing port 35 is exposed to exhaust gas at approximately atmospheric pressure. Since no negative pressure acts on the pressure chamber 33 of the recirculation control valve 28, the valve body 32 does not open and the exhaust gas is not recirculated to the intake system, but when the throttle valves 20, 20' are opened from closed. During acceleration, the negative pressure in the sensing port 35 increases, and this negative pressure acts on the pressure chamber 33 of the recirculation control valve 28, so that when the valve body 32 opens, part of the exhaust gas in the exhaust passage 8 is recirculated. aisle 29,
31 and the sub-recirculation control valve 30, the exhaust gas enters the jet communication passage 26, and is ejected together with the jet flow to the intake port during the intake stroke, thereby performing exhaust gas recirculation. When gas is introduced into the jet communication passage 26, both jet holes 27,
The jet from 27' to the intake port will be further accelerated by the recirculating exhaust gas.

Therefore, since the flow of the air-fuel mixture in the combustion chamber becomes more intense than when the exhaust gas is recirculated, a reduction in the combustion speed due to the exhaust gas recirculation can be avoided. 30 as described above, the throttle valve 20,
20', the sub-reflux control valve 30 starts to open after the throttle valve opens to a certain opening degree as shown by curve B in FIG. By configuring the throttle valve to open fully, it is possible to control the amount of exhaust gas recirculated to the intake system without too much or too little, and in the partial load range where the throttle valve is partially opened, it is possible to control the amount of exhaust gas recirculated to the intake system. It can be controlled so that it increases proportionately.

In addition, when the variable ventillary type carburetor 9 is used as in the above embodiment, the intake negative pressure in the load range where the opening degree of the throttle valve is large is lower than that when using a fixed ventillary type carburetor instead of a variable ventilated type carburetor. Therefore, when accelerating with the throttle valve wide open, the intake negative pressure rapidly decreases, causing the exhaust gas recirculation control valve 28 to close in a short period of time, resulting in insufficient exhaust gas recirculation. In this case, a negative pressure holding mechanism 43 consisting of a check valve 41 and an orifice 42 may be provided in the negative pressure extraction passage 36 from the sensing port 35 to the reflux control valve 28. That is, the large negative pressure at the 35 sensing ports at the beginning of acceleration is transmitted to the reflux control valve 28 without delay by the opening of the check valve 41 in the negative pressure holding mechanism 43, and while the reflux control valve 28 opens, the Even if the negative pressure in the sensing port 35 becomes small after a while, the negative pressure in the diaphragm chamber 33 of the reflux control valve 28 becomes smaller after a delay due to the negative pressure holding mechanism 43. Since the open state is maintained for the negative pressure holding time at , the time for exhaust gas recirculation during acceleration can be increased.

On the other hand, when the engine is idling or in a low load range, fuel is equally distributed and supplied from the slow system fuel passage 17 to both intake ports 4 and 4' via the balance passage 23 in an amount regulated by the idle adjustment screw 25. . In this case, when the exhaust gas recirculation passage 31 is connected to the balance passage 23, the cross-sectional area of the balance passage 23 must be considerably large in order to ensure a sufficient flow rate of the exhaust gas flowing through the balance passage 23. Must. However, if the cross-sectional area is increased, the pressure difference between the two intake ports 4 and 4' is reduced, and the pressure fluctuations between the two intake ports are large, making it difficult to perform fuel distribution properly. This will reduce the effect of accelerating the combustion rate.

In contrast, in the present invention, a balance passage 23 is provided independently from the jet communication passage 26, and the slow system fuel passage 17 is connected to the balance passage 23, while the exhaust gas is recirculated to the jet communication passage 26. The cross-sectional area of the balance passage 23 can be made small regardless of the recirculated exhaust gas, so the existence of the balance passage 23 reduces the effect of the jet flow from the jet communication passage 26. can definitely be avoided.

That is, by reducing the cross-sectional area of the balance passage 23 in this way, it is possible to prevent the pressure difference between both intake ports 4 and 4' from decreasing due to the existence of the balance passage 23. Fuel to both intake ports 4,
4', and the jet communication passage 2
The presence of the balance passage 23 can reduce the effect of the jet flow caused by the balance passage 23 being attenuated.

Although the above embodiments have been described in the case of a 4-cycle, 2-cylinder internal combustion engine, it goes without saying that the present invention can also provide similar effects in other multi-cylinder internal combustion engines. The device is not limited to variable ventilate type carburetors, but can also be applied to general compound type carburetors; however, it is said that the response will be much better if a variable ventild type carburetor is used. effective.

As described above, the present invention provides an intake jet type internal combustion engine with separate jet communication passages and balance passages, the jet communication passage is used as a recirculation passage for exhaust gas to the intake system, and the balance passage is used as a recirculation passage for exhaust gas from the carburetor. By connecting the system fuel passages to each other, the recirculated exhaust gas to the intake system does not suck out more fuel than necessary, while the recirculated exhaust gas is introduced to a location that is not cooled by the slow system fuel. There is no reduction in the communication area due to corrosion due to moisture in the exhaust gas or adhesion of carbon, and exhaust gas can be recirculated accurately and stably. can be significantly reduced, and the effect of the intake jet can be increased.

However, in an intake jet type internal combustion engine, the effect of promoting combustion by the jet flow through the jet flow communication passage is that as the load increases, that is, the opening degree of the throttle valve increases, the mutual communication in the jet flow communication passage increases. This is reduced by reducing the pressure difference between the intake ports.

On the other hand, in the present invention, when the exhaust gas is recirculated to the intake system by connecting the recirculation passage for the exhaust gas to the intake system to the jet flow communication passage as described above, the recirculation of the exhaust gas is A sub-recirculation control valve is provided in the passageway in conjunction with the throttle valve, and starts opening after the throttle valve opens to a certain opening degree, and is fully open before the throttle valve is fully opened. With this configuration, the amount of exhaust gas recirculated to the intake system can be controlled to be just the right amount and the amount of exhaust gas recirculated to the intake system can be controlled to increase in proportion to the opening of the throttle valve and the increase in load. Prevents the intake flow in the combustion chamber from decreasing in proportion to the throttle valve opening, or load, by increasing the exhaust gas recirculation amount in proportion to the throttle valve opening, or load, as described above. Therefore, the effect of promoting combustion by the jet stream can be reliably maintained even in a load range where the opening degree of the throttle valve is large.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a sectional view of the main parts of the engine, FIG. 2 is a sectional view taken from the side of FIG. 1,
Figure 3 is a cross-sectional view of Figure 1, and Figure 4 is a cross-sectional view of Figure 1.
5 is a diagram showing the movement mechanism of the throttle valve and the sub-reflux control valve, and FIG. 6 is a diagram showing the relationship between the throttle valve opening and the sub-reflux control valve opening. 1...Engine, A1...1st cylinder, A2...2nd
Cylinder, 4, 4'...Intake port, 9...Variable ventilate carburetor, 18...Throttle body,
19, 19'... Throttle passage, 20, 20'...
...Throttle valve, 23...Balance passage, 17...
... Slow system fuel passage, 25 ... Idle adjustment screw, 26 ... Jet communication passage, 27, 27' ... Jet hole, 29, 31 ... Exhaust gas recirculation passage, 28
...reflux control valve, 30...sub-reflux control valve, 35
...Sensing port, 36...Negative pressure extraction passage.

Claims (1)

[Claims] 1. One carburetor is connected to the intake ports of a plurality of cylinders in a multi-cylinder internal combustion engine via a throttle passage equipped with a throttle valve corresponding to each intake port, while each of the intake ports in the plurality of cylinders is In an internal combustion engine in which the air-fuel mixture is connected to the air-fuel mixture in the air-fuel mixture in the air-fuel mixture in the air-fuel mixture in the air-intake port in the other cylinder to the air-fuel mixture in the air-intake port in the other cylinder. , a balance passage is provided independently of the jet flow communication passage so that the throttle passages or the intake ports communicate with each other on the downstream side of the throttle valve; While connecting the slow system fuel passage, an exhaust gas recirculation passage for the intake system is connected to the jet communication passage, and the exhaust gas recirculation passage is normally biased closed by a spring and negative pressure is applied to the pressure chamber. Then, a reflux control valve is provided that opens against the spring, and a pressure chamber in the reflux control valve is connected to a sensing port provided at a location upstream of the closed position of the throttle valve via a negative pressure take-off passage. Further, in the exhaust gas recirculation passage, a sub-recirculation is provided in the exhaust gas recirculation passage, which is linked to the throttle valve and starts opening after the throttle valve opens to a certain degree, and is fully open before the throttle valve is fully opened. An internal combustion engine characterized by being equipped with a control valve.