JPS60145416A - Lamellar scavenging 2-cycle internal-combustion engine - Google Patents

Abstract

PURPOSE:To devise improvement of the thermal efficiency of an engine and quality of the exhaust gas by providing a sub-scavenging passage to connect a sub-scavenging port and the inside of a suction pipe in the downstream of a non- return valve, and forming a partition for dense and thin fuel-air mixture in the suction passage. CONSTITUTION:The suction of an engine is carried out by a reed valve 8 and a piston 18 which opens and closes a suction port 16. A partition to separate dense and thin fuel-air mixture is provided in a suction passage 9. When main scavenging ports 15 are opened in a scavenging stroke, the fuel-air mixture in a crankcase 17 flows into a cylinder 5 through the main scavenging ports 15. When a pair of subscavenging ports 12 are opened dence fuel-air mixture in the suction passage 9 flows into a sub-scavening passage 11 through an opening 10 and is supplied inside the cylinder 5 through the sub-scavenging ports 12. In this way, the blow-bye loss of fresh air is reduced and the thermal efficiency of the engine and the quality of the exhaust gas are improved.

Description

[Detailed description of the invention] The present invention relates to a stratified scavenged two-stroke internal combustion engine.

The inventor has already clarified that in a two-stroke internal combustion engine that has a check valve and a fuel supply device in the intake pipe, it is possible to separate rich and lean air-fuel mixtures in the intake pipe and achieve stratified scavenging (
Patent application: June 4, 1980 Patent application number: Patent application No. 1983
No. 8-100018). The present invention aims to achieve stratified scavenging by separating rich and lean air-fuel mixtures in an intake pipe in a two-stroke internal combustion engine that performs an intake action using a check valve and a piston valve.

An object of the present invention is to reduce the loss of fresh air in a two-stroke internal combustion engine by using a stratified Jfi of 1%, thereby improving thermal efficiency and exhaust gas.

Application examples of the present invention will be described below with reference to the drawings.

Figure 1 shows an example in which the present invention is applied to a Schneel scavenging crank chamber compressed air-cooled two-stroke gasoline engine, and Figure 2 is a three-dimensional view showing a part of the intake passage. It is symmetrical. This is done by the engine's intake beam valve (8) and a piston (18) that opens and closes the intake hole (16). This is the so-called piston lead method. Intake passage (9) near intake hole (16)
There is a separation wall (21) for rich and lean mixtures inside, 1m long! ! ! (21) V seen from beam valve (8)
The shape is close to a letter shape, and the middle side of the figure 7 is connected to the intake hole, and both sides of the figure 7 are connected to the openings (10) in the intake road of the auxiliary scavenging passage.

When the engine is running, the piston (18) rises and the intake hole (16)
) opens and the intake passage (9) and crank chamber (17) communicate with each other, the inside of the intake passage (9) becomes negative pressure, and the reed valve (8)
opens.

During the intake process, the mixture of fuel and air whose mixture ratio has been adjusted by the carburetor (6) normally flows into the crankcase through the intake passage and the intake hole, but the fuel supplied from the carburetor flows through the intake passage. Even within the intake passage, the unvaporized fuel has not yet sufficiently vaporized, and due to the difference in specific gravity with the surrounding gas, the unvaporized fuel flows in the lower part of the intake passage. Therefore, if a separation wall (21) having the shape shown in Fig. 2 is formed, components with a relatively heavy specific gravity including liquid fuel will be removed by inertia (see the arrows on both sides of the #I wall).
22) and is trapped in the intake passage, while the air-fuel mixture, which has a relatively light specific gravity and a low fuel component, mostly passes in the direction of the arrow (25) inside the upper part of the separation wall with a large cross-sectional area. It flows into the crank chamber (17) through the intake hole (16).

During the crank chamber compression stroke by the piston (18), the inside of the crank chamber (17) and the intake passage (9) are pressurized,
When the main scavenging air hole (15) opens during the scavenging stroke, the relatively lean air-fuel mixture in the crank chamber (17) passes through two pairs of main scavenging passages (14) and two pairs of main scavenging air holes (15) into the cylinder. (5). On the other hand, a pair of sub-scavenging holes (12)
When the holes are opened, the relatively rich mixture of fuel components trapped in the intake passages flows through the holes (10
) flows into a pair of sub-scavenging passages (11) and is supplied into the cylinder (5) via a pair of sub-scavenging holes (12).The timing of the main scavenging holes is earlier than that of the sub-scavenging holes. If you leave it there,
First, a 5-lean air-fuel mixture is supplied into the cylinder from the house air vent (15) near the exhaust hole (13), and a rich air-fuel mixture is supplied into the cylinder later from the sub-scavenging hole (12) far from the exhaust hole. Distributed in the lateral space. Therefore, in the cylinder, the rich mixture is distributed on the side opposite to the exhaust hole, and the lean mixture is distributed in the center in a manner that suppresses the flow of the rich mixture toward the exhaust hole, thereby achieving stratified scavenging.

Contrary to this application example, the sub-scavenging hole is provided on the exhaust hole side, the sub-scavenging passage connected to the sub-scavenging hole is connected to the intake passage, and the thick/thin separating wall in the intake passage is appropriately determined. It is also possible to easily guide the rich mixture into the crank chamber and the lean mixture into the sub-scavenging passage.

As described above, according to the present invention, stratified scavenging air can be obtained without complicating the engine structure or complicating operation control. According to experiments, the thermal efficiency was improved by 10% and the unburned hydrocarbon content in the exhaust gas was improved by about 15% by applying the present invention.

[Brief explanation of drawings]

FIG. 1 is a diagram of a Schnürle scavenging type crank chamber compressed air-cooled two-stroke gasoline engine to which the present invention is applied, and FIG. 2 is a three-dimensional view showing a part of the intake passage of the engine of FIG. 1. In Figures 1 and 2, (1)...Cylinder head, (2)...Cylinder, (3)...Crankcase, (4)...Spark plug, (5)...Cylinder internal space , (6)... Carburetor, (7)... Throttle valve, (8)... Reed valve, (9)... Intake passage, (1
0)...A pair of auxiliary M air passage intake passage internal holes, (11
)...1 pair of sub-scavenging passages, (12)-...1 pair of sub-scavenging holes, (15)...exhaust hole, (14)...2 pairs of main scavenging passages, (15)-・2 pairs of main scavenging holes, (16)・
...Intake hole, (17)...Crank chamber, (18)--
・Piston, (19)...Conrod, (20)...
- Crank arm, (21) - Rich-lean mixture separation wall, (22) - Direction of flow of rich mixture, (25) -
...This is the direction in which the lean mixture flows.

Claims (1)

[Claims] In a two-stroke internal combustion engine that opens and closes an intake hole provided in the inner wall of the cylinder by the side surface of the piston, and has a fuel supply device and a check valve in the middle of the intake pipe connected to the intake hole. In addition to the normal open scavenging hole and the normal scavenging passage that connects the normal scavenging hole and the crank chamber, there is a sub-scavenging hole provided on the inner wall of the cylinder, and the sub-scavenging hole downstream of the check valve. An auxiliary scavenging passage is provided downstream of the check valve to connect the air-fuel mixture containing a large amount of liquid fuel or fuel vapor to other air-fuel mixtures using gravity, inertia, centrifugal action, etc. A separate V & air passage is formed to separate the fuel-rich mixture from the lean mixture, and the mixture is supplied into the cylinder from the crank chamber through the normal scavenging passage and normal scavenging holes. , a crank chamber compression two-stroke internal combustion engine, characterized in that the fuel concentration of the air-fuel mixture supplied from the trachea to the cylinder through the sub-scavenging passage and the sub-scavenging hole is greatly changed.