JPS5968519A - Stratified scavenging two-stroke-cycle internal- combustion engine - Google Patents

Abstract

PURPOSE:To reduce a fuel blow over under high load conditions by providing channel-like grooves or protruding partitions on outboard walls of scavenging passages in the direction of the flow of the scavenging gas. CONSTITUTION:The fuel mixture enters into a cylinder 3 from a crank chamber 1 with circular tracks 2, 2'. As objects having a weight is affected by a centrifugal force when flowing through the passage, fuel particles and lubrication oil particles in the fuel mixture are densely distributed near outboard walls, and as shown in the drawings densely distributed in the upper area at scavenging port outlets in the cylinder. When the flow is converted from the vertically stratified distribution to the laterally stratified distribution at the scavenging port by grooves C and partitions D, a stratified scavenging gas which is denser in the forward part of the scavenging port (opposite to the exhaust port side) is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention collects lubricating oil particles, fuel droplets, and fuel particles in the air-fuel mixture supplied from the crank chamber into the cylinders in a scavenging air passage in a premixed two-stroke engine, and transports them into the cylinders. The present invention relates to a scavenging method and structure of the scavenging path, which suppresses the ineffective blowout of fuel that short-circuits or penetrates through the exhaust hole due to scavenging by intensively supplying the fuel to the opposite side of the exhaust hole.

In general, premixed two-cycle engines such as carburetor type use the Schnillet scavenging method and the reverse loop scavenging method, which supply air-fuel mixture into the cylinder via the scavenging passage using the crank chamber pressure. As the ratio of scavenging air increases, that is, as the air supply ratio increases, the amount of fuel that escapes ineffectively from the exhaust hole increases, which is the cause of the low thermal efficiency of this type of engine and the large amount of HO components in the exhaust gas.

An object of the present invention is to provide a two-stroke engine which improves this drawback of the conventional engine by performing effective stratified scavenging and achieves both an improvement in engine thermal efficiency and a reduction in exhaust components.

In general, the soft contact loss of fuel in a two-stroke carburetor engine is mainly caused by the reverse protrusion of the leading air-fuel mixture, a direct short circuit from the scavenging hole to the exhaust hole, and overflow of hot air mixture in the cylinder at the beginning of the piston rise. In both cases, it is observed that more air is blown through from the rear of the scavenging hole, which is closer to the exhaust hole.

In addition, there is a large amount of fuel in the form of liquid streams, droplets, and particles in the air-fuel mixture that reaches the cylinder from the carburetor, and this is more common in small engines than in large engines.
It is more common in water-cooled types than in air-cooled types.

This phenomenon is caused by the fact that the atomization characteristics of the carburetor, the time factor from the carburetor to the cylinder, the ambient temperature, etc. are dominant in the vaporization of the fuel.

The present inventor visually observed this phenomenon, and using the interlocking law of conservation and centrifugal force that fuel particles undergo in the air-fuel mixture flow in the scavenging passage, collects and guides the particles on the outer wall of the scavenging passage, and transfers and supplies them to the front of the scavenging hole. We confirmed that this is possible and that it is possible to control invalid fuel blow-through.

The structure of the present invention consists of liquid fuel having gravity in the air-fuel mixture, droplets,
A guide groove or guide partition wall is provided to collect and guide particles, lubricating oil components, etc. mainly on the outer wall of the scavenging air passage, and the flow energy of the air-fuel mixture diverted through the scavenging air passage at high speed is used to guide the particles and lubricating oil components into the cylinder. The purpose is to supply a rich and dense air-fuel mixture to the front position of the opening scavenging hole.

To explain the embodiment of the present invention with reference to the drawings, the scavenging passage system generally starts from the crank chamber (1) in a circumferential trajectory (
2) A heavy substance flowing through this channel is inevitably affected by centrifugal force. Therefore, fuel particles, lubricating oil particles, etc. in the air-fuel mixture naturally have a dense distribution on the outer wall, and as shown in Figure A, they form a dense distribution in the upper part at the exit of the scavenging hole of the cylinder. As shown in Figure 2, the groove (0) and partition (D) provided on the scavenging outer wall divert the flow from the upper and lower layered distribution in the scavenging hole to the left and right layered distribution, and the flow is transferred to the front part of the scavenging hole (on the opposite side of the hole). The stratified scavenging air (B) with high density is produced and is supplied into the cylinder.

It is obvious that if a richer mixture is supplied to the cylinder from the front of the scavenging hole, the mixture supplied from the rear can be too lean, such as air alone, to sufficiently achieve the purpose of the engine-required mixture. .

The present invention has achieved the remarkable result of reducing by 50% the ineffective fuel blow-through that was commonly seen under high loads (air supply ratio 0.7), which has resulted in an improvement in thermal efficiency, an increase in engine specific output, and an increase in exhaust gas. Engine performance such as reduced fuel consumption and unburned hydrocarbons is dramatically improved, and the effects are significant.

Although this example describes a gasoline-fueled engine, effective stratified scavenging is also possible when using kerosene, which is less volatile than gasoline, as fuel, or when using alcohol, and its effect on energy saving and low pollution of the engine. One of the features of the present invention is that it is large.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the scavenging passage system of a two-cycle engine with a circumferential locus. Figure 2 shows the density distribution of the mixed air flow. Fig. 2 is a three-dimensional diagram showing the configuration of the scavenging flow path according to the present invention, and its (,) and (d) cross-sectional views, where (0) is the groove structure, and (0) is the partition wall. Structure. Figure 6 is an explanatory cross-sectional diagram of a cylinder showing the blowout loss of a conventional two-stroke engine. In the figure, (1)...Crank chamber, (2)...Scavenging air passage, (3)...Cylinder, (4)...Ignition plug, (5
)...guiding groove in the scavenging passage, (6)...shelf wall in the scavenging passage, (7)...piston. Figure 1 (4) Figure 2 Figure 3 - ■Blade

Claims (1)

[Claims] In a crank chamber compressor mixed two-stroke engine, a concave groove or a convex partition wall in the flow direction of the scavenging air is provided on the outer wall of the scavenging air passage leading from the crank chamber to the cylinder. The rich air-fuel mixture, fuel droplets, lubricating oil particles, etc. in the air-fuel mixture supplied to the cylinders by the scavenging passages are diverted to the cylinders by the guide passage formed by grooves, partitions, etc. provided on the outside of the scavenging passages. A two-stroke stratified scavenging engine characterized by controlling blow-through of fuel due to scavenging action by supplying fuel intensively to the side opposite to the exhaust port.