JPS5924816Y2 - Exhaust gas purification device for spark ignition internal combustion engines - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a spark-ignition internal combustion engine, particularly a stratified combustion internal combustion engine.

By the way, air is sucked into the cylinder near the end of the suction stroke, forming a layer of rich mixed gas at the top of the cylinder and a layer of air or lean mixture near the top of the piston. An opening is provided in the inner wall of the cylinder that opens when the piston approaches bottom dead center, and air is sucked into the cylinder through the opening via a reed valve to perform so-called stratified charge combustion and improve the exhaust gas purification effect. An example of the prior art that does this is, for example, Japanese Patent Application Laid-Open No. 51-48008.
It is known from the publication No. 1, and it also has an opening provided in the inner wall of the cylinder at a position that opens within 50 degrees from the bottom dead center and communicates with the exhaust pipe. An example of prior art in which a part of the exhaust gas is inhaled to increase the purification effect of the exhaust gas is disclosed in Japanese Patent Laid-Open No. 48
It is known from the publication No.-48832.

The present invention improves these prior art techniques by pre-mixing air with the exhaust gas recirculated to the cylinder in the latter, thereby achieving rapid combustion up to the end of the explosion stroke in the latter EGR using only the exhaust gas. The latter problem, such as a decrease in combustion speed and a significant decrease in output, can be eliminated by preventing the deterioration of the air and the exhaust gas, depending on the operating condition of the engine. By automatically controlling the amount of mixed gas and by making it possible to appropriately select the mixing ratio, it is possible to maintain a simple configuration for optimal combustion conditions and even operational conditions, thereby improving exhaust gas purification. It is characterized by being able to achieve further improvement.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the figure, 1 is a cylinder, 2 is a piston, 3 is an intake valve,
4 is an exhaust valve, 5 is an intake pipe, 6 is an exhaust pipe, and 7 is an air cleaner.The cylinder 1 is provided with an opening 8 that opens near the bottom dead center of the piston 2, and this opening and the middle of the exhaust pipe 6 are used for intake. tube 9
Connect with.

The intake pipe 9 is provided with a flow rate adjusting throttle valve 10, and the throttle valve 11 in the intake pipe 5 is interlocked with the throttle valve 11.

Furthermore, a suction pipe 12 that communicates with the atmosphere via a check valve 13 is branched into the suction pipe 9, and this suction pipe has a
A restrictor 14 is provided to adjust the flow rate.

As shown in FIG. 2, the piston 2 is also provided with a piston ring 15 at a position below the opening 8 at the top dead center, so that the opening 8 does not communicate with the inside of the crankcase.

With the above configuration, when the piston 2 descends near the bottom dead center during the suction stroke, the opening 8 opens, and the exhaust gas in the exhaust pipe 6 passes through the suction pipe 9 and is sucked into the cylinder due to the negative pressure inside the ring cylinder. At the same time, air is also sucked in through the suction pipes 12 and 9 via the check valve 13, and therefore,
A mixture of air and exhaust gas is drawn into the cylinder.

At this time, by appropriately adjusting the throttle 14, the mixture ratio of air and exhaust gas can be made suitable for combustion control.

In addition, since the flow rate adjustment throttle valve 10 is linked with the throttle valve 11 of the carburetor, the intake amount of the mixed gas of air and exhaust gas is controlled according to the operating state of the engine, so that That amount of gas will be inhaled.

The mixture of air and exhaust gas sucked in in this way mixes with the air-fuel mixture in the cylinder at the top of the piston, so the air-fuel mixture in that area becomes lean, while the air-fuel mixture near the spark plug has a moderate amount of air. The fuel ratio, and therefore the air-fuel mixture, becomes what is called a stratified mixture.

FIG. 2 shows the state at the time of ignition. Since a rich air-fuel mixture layer 17 is formed near the spark plug 16, ignition is ensured, and then combustion of a lean air-fuel mixture is achieved. The exhaust gas purification effect can be improved.

Moreover, since the maximum combustion temperature can be controlled by partially recirculating the exhaust gas, the generation of nitrogen oxides can be particularly suppressed.

In addition, even during the expansion stroke, when the piston reaches the bottom dead center, the opening 8
However, as shown in Fig. 3, the exhaust valve 4 opens during the descent of the piston and the pressure inside the cylinder is about atmospheric pressure, so air and exhaust gas flow in through the suction pipes 9 and 12. Never.

FIG. 4 shows an embodiment in which the present invention is applied to a multi-stage combustion internal combustion engine.

The multi-stage combustion internal combustion engine includes a sub-piston 18 protruding from the top of the piston 2 and a recess 19 in the ceiling of the combustion chamber in which the sub-piston engages, and the sub-piston 18 moves into the recess during a predetermined period before and after top dead center. 19, the combustion chamber is divided, and combustion occurs in stages in each combustion chamber.

By performing combustion in multiple stages in this manner, the maximum combustion temperature can be lowered and the generation of nitrogen oxides can be suppressed.

In this embodiment, as in the previous embodiment, an opening 8 is provided which opens when the piston approaches the bottom dead center, and this is communicated with the exhaust pipe 6 and the atmosphere through suction pipes 9 and 12. is the same as the previous embodiment and has a similar effect.

In particular, in this embodiment, since the auxiliary piston protrudes, the intake air and exhaust gas are prevented from flowing upward, which prevents the air-fuel mixture near the ignition plug from diluting. , the air-fuel mixture can be ignited more reliably.

As is clear from the above, according to the present invention, air and exhaust gas are sucked by the negative pressure inside the cylinder, so there is no need to provide a special air injection device such as a pump. Furthermore, since the opening to the cylinder inner wall and part of the intake pipe are shared for supplying exhaust gas and fresh air, the configuration is simple and does not consume power. In addition to being able to economically supply exhaust gas and fresh air into the cylinder, the flow rate adjustment throttle valve is installed closer to the opening to the cylinder inner wall than the branch of the suction pipe, so that only one throttle valve can supply exhaust gas and fresh air into the cylinder. In addition to being able to easily control the amount of exhaust gas and air supplied, the throttle valve is designed to work in conjunction with the throttle valve in the intake pipe, so that the amount of intake gas and air can be easily controlled. Since the amount of mixed gas of air and exhaust gas is automatically controlled, the engine can be operated smoothly.

Moreover, the amount of air taken into the cylinder can be adjusted by operating the throttle valve, so the mixture ratio of this air and exhaust gas can be appropriately selected to achieve the optimal combustion state to achieve the desired exhaust gas purification effect. be able to.

From the above, in this invention, by pre-mixing air with the exhaust gas that is recirculated to the cylinder, the combustion condition deteriorates rapidly until the end of the explosion stroke compared to the conventional EGR that does not mix the air. Therefore, there is no significant decrease in combustion speed or output, and the amount of mixed gas of air and exhaust gas taken into the cylinder is automatically adjusted depending on the operating condition of the engine. Moreover, since these mixing ratios can be selected appropriately, the optimum combustion state and thus the operating state can be ensured with the above-mentioned simple configuration, and therefore, the purification of exhaust gas can be further improved. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, FIGS. 2 and 3 are views showing the operation, and FIG. 4 is a cross-sectional view showing another embodiment of the present invention. 1...Cylinder, 2...Piston, 3
...Intake valve, 4...Exhaust valve, 5...
...Intake pipe, 6...Exhaust pipe, 7...
Air cleaner, 8...Opening, 9...Suction pipe, 10...Flow rate adjustment throttle valve, 11...
... Throttle valve, 12 ... Suction pipe, 1
3... Check valve, 14... Throttle, 15... Piston ring, 16...
Spark plug, 17... Rich mixture layer, 18...
- Sub-piston, 19... recess.

Claims (1)

[Scope of utility model registration request] An opening is provided in the inner wall of the cylinder at a position that opens when the piston approaches bottom dead center, and the opening is connected to the middle of the exhaust pipe by a suction pipe, and the suction pipe is branched and a check valve is provided. A flow rate adjustment throttle valve that communicates with the atmosphere side and is interlocked with a throttle valve of the intake pipe is provided between the branch part of the intake pipe and the opening to the top of the cylinder; An exhaust gas purification device for a spark ignition internal combustion engine, characterized in that a throttle is provided between a check valve leading to the engine.