JPS59173518A - Two-cycle internal-combustion engine with layers of scavenging air - Google Patents

Abstract

PURPOSE:To improve the efficiency of an engine and reduce unburned ingredients by providing small chambers on the inner wall of a cylinder, allowing scavenging air flow to collide against these small chambers to damp down the quantity of motion of said scavenging air, and producing layers of scavenging air. CONSTITUTION:A scavenging flow damping chamber 18 is provided on the inner wall of a cylinder on the opposite side of an exhaust port 14 against the axis of the cylinder 1. A plural number of scavenging ports which are symetrically positioned to each other with respect to a line connecting the center of the cylinder 1 to the center of the exhaust port 14, are divided by 27, and 19, 20 respectively. Thereby scavenging air flowing out partitions 15, 16 for controlling scavenging flow, into each pair of ports 17, of the scavenging ports 17, 19 collide against each other, while also against the inner wall of the chamber 18, and are prevented from being diffused. Scavenging airs flowing out of the scavenging ports 27, 20 also collide against each other, pushing out incinerating gas toward the exhaust port 14. Thereby, new air is distributed on the opposite side of the port 14 within the cylinder 1, while incinerating gas is distributed on the exhaust port side.

Description

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

In order to reduce blow-through of fresh air and significantly improve thermal efficiency in a two-cycle internal combustion engine, it is necessary to prevent the mixing of fresh air and residual gas in the cylinder as much as possible, exhaust combustion gas in a stratified manner, and trap fresh air in the cylinder. The realization of scavenging is inevitable.

If the momentum of the scavenging flow is large, a large amount of fresh air blows through at the tip, and the fresh air is mixed well with the residual gas and is discharged as a mixed gas. Therefore, in order to realize stratified scavenging, it is necessary to attenuate the momentum of the scavenging air flow within the cylinder and distribute the fresh air mass away from the exhaust hole.

The present invention effectively attenuates the momentum of the scavenging air by utilizing collisions between the scavenging air flows and collisions between the scavenging air flows and the wall to achieve stratified scavenging, thereby achieving excellent thermal efficiency and purifying the exhaust gas. The purpose is to provide internal combustion engines.

A feature of the present invention is that a scavenging air flow attenuation chamber for colliding and attenuating the scavenging air flow is provided on the inner wall of the cylinder on the opposite side of the exhaust hole with respect to the cylinder axis, or the momentum of the scavenging air is The present invention will be described in detail with reference to the drawings below.

Fig. 1 is a sectional view including the cylinder axis of a crank chamber compressed cotton schnula scavenged air-cooled two-stroke internal combustion engine having a scavenging air flow damping chamber, and Fig. 2 shows the action of the scavenging air flow damping chamber in the engine of Fig. 1. FIG.

In FIGS. 1 and 2, with respect to the central axis of the cylinder (1),
A scavenging airflow damping chamber (18) is provided on the inner wall of the cylinder opposite to the exhaust hole (14), and the scavenging boat is located symmetrically with respect to a line connecting the center of the cylinder and the center of the exhaust hole, and is used to control the scavenging airflow. The partition walls (i5) and (16) divide the pair of scavenging boats into (17) and (18) and (19) and (2), respectively.

Now, when the piston rises, air flows into the crank chamber (8) through the mixture throttle valve (12) and the intake pipe (11).
The fuel mixture is compressed by the descent of the piston (4),
When the scavenging cage is opened, the scavenging air flow flows into the cylinder. Among the scavenging airflows whose directions are controlled by the scavenging boats with bulkheads, the scavenging air coming out of the scavenging boats (17) and (19) collides with each other as shown in Figure 2, and at the same time, the scavenging air flows into the scavenging air flow damping chamber (18).
It collides with the inner wall and is prevented from spreading.

On the other hand, the direction of scavenging air is controlled upwards in the cylinder) (27
), (20) collide with each other and push out the combustion gas to the exhaust hole (14). In this way, fresh air is well distributed in the cylinder interior space in the direction opposite to the exhaust hole with respect to the cylinder center axis, and combustion gas is distributed on the exhaust hole side.

3 and 4 show an example of the invention in which a piston having a stepped crown is used in place of the normal piston (4) in the internal combustion engine of FIG. 1.

FIG. 5 is a cross-sectional view including the cylinder axis, and FIG. 4 is a cross-sectional view in the cylinder radial direction. In both figures, the piston crown (1
3) The exhaust side is higher than the part that touches the wall on the exhaust side of the scavenging boat, and it is also stepped and steep.

This step provides better directional control of the scavenging air flow exiting from the scavenging boats (27) and (20), and also prevents fresh air from dispersing near the scavenging air flow attenuation chamber. Such a piston shape further promotes stratification of scavenging air.

Figure 5 shows a sub-scavenging air bow (for scavenging and airflow damping) (2
1) is a diagram showing an example of a crank chamber pressure cotton schnule scavenging type air-cooled two-stroke internal combustion engine.

In Fig. 5, as the piston descends, the sub-scavenging air bow) (2
When 1) is opened, an auxiliary scavenging passage (2) that communicates with the crank chamber is opened.
Fresh air flows into the cylinder through 2).

When the pair of main scavenging bows (2!l) are opened at approximately the same time as the sub-scavenging bows) (21), scavenging air whose direction is controlled in the direction of the sub-scavenging boats flows into the cylinder, and the scavenging air flows into the cylinder. It collides with the scavenging air from the boat. The new air collides oppositely and is attenuated, and is distributed in the cylinder space on the opposite side of the exhaust hole. The scavenging air that flows into the cylinder from the pair of scavenging holes (24) collides with each other and reduces the speed while sending the combustion gas to the exhaust hole (26).
push it out.

In this way, in the example of Fig. 5 as well, gas with a high concentration of fresh air is distributed in the space within the cylinder farthest from the exhaust hole, and gas with a high concentration of combustion gas is distributed in the space near the exhaust hole. This reduces the amount of fresh air blowing through.

In addition, some conventional two-cycle engines have a sub-scavenging boat installed on the cylinder wall opposite the exhaust hole to increase output, but in this case, the scavenging air outflow direction from the sub-scavenging boat is the exhaust direction. facing the hole side or above the exhaust hole,
Moreover, since the direction control of the main and subsurface scavenging air is not precise, blow-by of fresh air often increases. Therefore, the invention example shown in FIG. 5 is completely different from the conventional scavenging system.

In the case of the invention example shown in FIG. 5 as well, when a piston having a stepped crown shown in FIGS. 3 and 4 is used, the layered effect becomes even greater.

In the above invention example, precise fii (control force (control force) of the scavenging air flow is essential when the scavenging air collides with each other, or between the scavenging air and the wall, and for this purpose, a plurality of paired scavenging boats are used. ,
Alternatively, the partition wall for controlling the scavenging air flow may be J['.

When a main scavenging boat with such a shape is combined with a scavenging air flow attenuation chamber or a sub-scavenging air boat for scavenging air flow attenuation, in-shape scavenging is achieved, thereby improving engine thermal efficiency and reducing unburned fuel components in the air. koto power (able to do)

[Brief explanation of the drawing]

Fig. 1 is a sectional view including the cylinder axis of a crank chamber compression schnular scavenging air-cooled two-stroke engine with a scavenging airflow damping chamber, and Fig. 2 shows the action of the scavenging airflow damping chamber in the engine shown in Fig. 1. FIG. In Figures 1 and 2, (1)...Cylinder, (2)
... Cylinder IJ cylinder head, (3) ... Cylinder internal space, (4) ... Piston, (5) ... Combustion chamber, (6)
...Spark plug, (7)--Crankcase, (8
)...Crank chamber, (9)...Crank web, (
10)...Connecting rod, (11)...Intake pipe, (1
2)...Air mixture throttle valve, (14)...Exhaust hole, (1
5), (16)...Scavenging boat bulkhead, (17), (1
9), (20), (27)...Scavenging boat, (18)
...Scavenging air flow damping chamber, Figs. 5 and 4 are examples of the case where a piston with a stepped crown is used in the internal combustion engine of Fig. 1. FIG. 5 is a diagram showing the scavenging behavior of a crown chamber compression schnula scavenging air-cooled two-stroke engine equipped with a sub-scavenging boat for attenuating the scavenging air flow. (22)... Sub-scavenging passage, (23),
(24) Main scavenging boat bulkhead, (25) Main scavenging boat bulkhead, (26) Exhaust hole. 9

Claims (1)

[Claims] (1) A small chamber (hereinafter referred to as a "scavenging air flow damping chamber") is provided on the inner wall of the cylinder on the opposite side of the exhaust hole with respect to the cylinder center axis, and a part of the scavenging air flow or By colliding all of them, the momentum of the scavenging air is attenuated, preventing the scavenging air from reaching the exhaust hole from the cylinder inner wall along the combustion chamber wall, and allowing fresh air to stay in the cylinder interior space away from the exhaust hole. A two-cycle internal combustion engine with the following characteristics: (2) A sub-scavenging boat (hereinafter referred to as "sub-scavenging boat for scavenging air flow attenuation") is provided on the opposite side of the exhaust hole with respect to the cylinder center axis, and the outflow direction of the scavenging air from the sub-scavenging boat is the reciprocating direction of the piston. By colliding part or all of the main scavenging air flow and the sub-scavenging air flow, which are strongly directionally controlled toward the sub-scavenging boat side, with each other, the momentum of the scavenging air is attenuated and the new scavenging air is generated. A two-cycle internal combustion engine that distributes air between the cylinder chambers away from the exhaust hole. (3) In "Claim (1)," a pair of scavenging boats configured to strongly control the direction of part or all of the scavenging airflow to the scavenging airflow damping chamber prevent short circuits of fresh air to the exhaust hole. At the same time, part or all of the pair of scavenging air flows collide inside or near the scavenging air flow attenuation chamber to attenuate the momentum of the scavenging air, thereby causing fresh air to stay in the cylinder interior space away from the exhaust hole. (4) In "Claims (2) and (3)," the scavenging boat is divided into a plurality of parts to control the scavenging air flow, or a thin A reverse scavenging two-cycle internal combustion engine characterized in that a wall is provided inside the scavenging gate. (5) In "Claims (1) to (4)", the piston crown is provided on the exhaust side wall of the scavenging boat. The scavenging air flow can be controlled and the scavenging air flow of fresh air can be attenuated by making the exhaust side higher than the part that touches the vicinity, and lowering the scavenging air flow attenuation chamber or sub-scavenging boat for scavenging air flow attenuation, and making the steps steeper. A two-cycle internal combustion engine with even more reliable distribution of sub-scavenging air to the chamber or boat side for attenuating the scavenging air flow.