JPH1150850A - Two-cycle internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent blow-by of fuel and improve fuel consumption and exhaust gas characteristic. SOLUTION: This two-cycle internal combustion engine is constructed to blow out the collected liquid fuel adhered to the cylinder inner wall surface from a scavenge passage far away from an exhaust port into a cylinder and blow out lean mixture from a scavenge passage near the exhaust port into the cylinder and to form, in a combustion chamber 3, a directive wall surface 3' for directing thick mixture formed by such structure toward the opposite exhaust port side when the thick mixture trends to flow from the combustion chamber into the cylinder. In collecting the liquid fuel adhered to the cylinder inside wall surface, it is constructed to either collect it in an annular groove 11 formed on the cylinder inside wall surface or the crankcase inside wall surface as a first structure or, as a second structure, to collect it in a receiver 13 formed and equipped as a separate body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stroke internal combustion engine, and more particularly to a two-stroke internal combustion engine in which fuel supplied into a cylinder is reduced in blow-through loss.

[0002]

2. Description of the Related Art In general, in a crankcase compression type two-stroke internal combustion engine in which an air-fuel mixture is sucked into a crankcase, exhaust gas in a cylinder is scavenged by an air-fuel mixture in a substantially homogeneous state.
Blow-through of the air-fuel mixture is inevitable, but blow-through loss of fuel occurs in proportion to the amount of blow-through. Therefore, a large amount of fuel blow-through deteriorates fuel economy and increases harmful components in exhaust gas.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to collect liquid fuel adhering to the inner wall surface of a cylinder and eject the liquid fuel into a cylinder from a place far away from an exhaust port in a scavenging process. When trying to flow out of the combustion chamber into the cylinder, it is directed to the side opposite to the exhaust port by the direction wall formed in the combustion chamber to prevent blow-through, thereby improving fuel efficiency and exhaust gas characteristics. is there.

[0004]

SUMMARY OF THE INVENTION In order to solve the conventional disadvantages, the present invention collects liquid fuel adhering to the inner wall surface of a cylinder, ejects the collected liquid fuel from a scavenging passage far from an exhaust port into the cylinder, and exhausts the fuel. From the scavenging passage near the mouth, a lean mixture was injected into the cylinder. In addition, the combustion chamber is provided with an orienting wall that is oriented in the direction opposite to the exhaust port when the rich mixture formed by this configuration is about to flow out of the combustion chamber into the cylinder. In collecting the liquid fuel attached to the cylinder inner wall surface, the liquid fuel is collected in an annular groove formed in the cylinder inner wall surface or the crankcase inner wall surface as a first structure, or formed as a separate structure as a second structure,
It was configured to collect on the equipped receiver.

[0005]

FIG. 1 shows an embodiment of a two-stroke internal combustion engine according to the present invention. First, an annular groove 11 is formed at the lower end of a cylinder 2 in FIG. It is connected to a scavenging passage 10 formed at a position far away from the opening (opening of the exhaust passage 8 to the inner wall surface of the cylinder). A scavenging passage 9 (a pair) is formed at a position near the exhaust port. When the intake passage 6 is opened by the upward stroke of the piston 1, the air-fuel mixture is sucked into the crank chamber 5 via the carburetor 7. Collision and adhesion to liquid fuel,
Due to gravity and the scraping action of the piston 1, the annular groove 11
Collected in. The collected liquid fuel is transferred to the scavenging passage 10
When it is opened, it is ejected into the scavenging passage 10 through the communication hole 12 and further flows into the cylinder 2 from the scavenging passage 10.
Thus, since all the liquid fuel adhering to the inner wall surface of the cylinder is supplied into the scavenging passage 10 (formation of a rich mixture), a lean mixture is ejected from the scavenging passage 9 into the cylinder, and exhaust gas is mainly generated by the lean mixture. It is scavenged. Reference numeral 3 denotes a combustion chamber having an orienting wall surface 3 '. When the rich mixture injected from the scavenging passage 10 flows into the combustion chamber 3 and then reverses and tries to flow out into the cylinder, it is oriented in a direction opposite to the exhaust port. The gas flows in a direction away from the exhaust port and is prevented from flowing into the exhaust passage 8 (a direction away from the exhaust port means a direction away from the exhaust port). The mixture remaining in the cylinder is ignited near top dead center while being compressed by the rising stroke of the piston 1 and burns, generating explosive power. Regarding the scavenging passages 9 and 10, the latter should be opened slightly later than the former. FIG. 3A shows an embodiment in which the scavenging passage 10 communicates with the crank chamber 5 and the communication hole 12, but communicates only with the latter. Also, the annular groove 11
FIG. 1 (b) is a partial view of an embodiment in which is formed on the inner wall surface of the crankcase.

In the present invention shown in FIG. 1 (c), the liquid fuel adhering to the inner wall of the cylinder is collected in a receiver 13 formed and provided as a separate body (the receiver 13 is separate from the cylinder and the crankcase). This is ejected into the scavenging passage 10 through the communication hole 12 in the scavenging process, and further flows into the cylinder from the scavenging passage 10 far away from the exhaust port. The receiver 13 has a shroud 14 inside and is held down by the lower end of the cylinder in order to guide the collected liquid fuel to the communication hole 12 (it is preferable to prevent leakage of the fuel by using packing). As described above, the rich mixture is ejected from the scavenging passage 10 and the lean mixture is ejected from the scavenging passage 9 into the cylinder. Reference numeral 3 'denotes an orienting wall surface which is oriented in the direction opposite to the exhaust port when the rich mixture from the scavenging passage 10 flows out in reverse.
It does not face the exhaust port side as completely as (a), but it reverses and flows out the rich mixture away from the exhaust port and plays a sufficient role to prevent fuel blow-through. in this case,
The orienting wall surface 3 'is located outside the inner wall surface of the cylinder in FIG. 1 (a), but is located inside the inner wall surface of the cylinder in FIG. 1 (c), and is located far away from the exhaust port as shown in FIG. (In FIG. 2B, FIG.
(B) It is farther from the exhaust port). By the way, many fuel particles that do not adhere to the inner wall surface of the cylinder and float in the crank chamber later adhere to the peripheral wall of the crank chamber and flow as liquid fuel.
It is desirable to introduce this liquid fuel into the scavenging passage 10 as indicated by the arrow by the rotation of, so that a leaner air-fuel mixture can be ejected from the scavenging passage 9. This scavenging passage 10 is more effective if an inlet is formed at the bottom of the crankcase. The scavenging passage 10 in FIG. 1A can also have such a configuration. FIG. 1 shows the scavenging passage 9
The normal type shown in (a) may be used.
A distance difference of a component in the diameter direction of the cylinder passing through the center of the exhaust port is provided between the outlet portion and the predetermined portion on the downstream side. It is desirable to have a configuration in which the roads are connected by a curved road. As a result, when the air-fuel mixture is ejected from the scavenging passage 9 into the cylinder, a rich air-fuel mixture is generated on the side opposite to the exhaust port by centrifugal separation.
The lean mixture is distributed toward the exhaust port side (Fig. 1
(A) The scavenging passage 9 can also be configured in this manner.)
In FIG. 1 (c), the liquid fuel adhered to the inner wall surface of the cylinder and collected from a plurality of locations enters, and then is ejected into the cylinder from a scavenging passage 10 far from the exhaust port. This is shown in FIG. That is, the liquid fuel adhered and collected on the inner wall surface of the cylinder enters from a plurality of locations (small holes 16 and communication holes 12) and then is ejected from the scavenging passage 10 into the cylinder. Small hole 1
The liquid fuel that has entered from the cylinder 6 is ejected into the scavenging passage 10 through the communication hole 12 through the annular passage 15 formed at the lower end of the cylinder.
This is because a pressure drop occurs due to the velocity energy ejected into the inside of the nozzle and the air is sucked through the small hole 16. In the drawing, packing is sandwiched between the lower end of the cylinder and the receiver 13. In FIG. 1, the number of the scavenging passages 10 far away from the exhaust port is one, but it is also possible to make a pair (two).
This is shown in FIG. 3 (c) when viewed from above the cylinder. Next, considering the flow inside the scavenging passage 9 in FIG. 1A, a part of the air-fuel mixture adheres to the inner wall surface of the scavenging passage 9 and liquefies, forming a liquid film toward the cylinder. Therefore, FIG.
By forming the transfer wall surface 17 (inclined surface) for causing the liquid fuel adhering to the inner wall surface of the scavenging passage 9 to flow to the inner wall surface of the scavenging passage 9 in the direction opposite to the exhaust port (arrow indicated by a broken line) as shown in (d), Since these liquid fuels are biased on the inner wall surface of the scavenging passage 9 in the direction opposite to the exhaust port, when injected into the cylinder, a rich mixture is distributed far away from the exhaust port, and a lean mixture is distributed near the exhaust port. In addition, it is possible to prevent fuel from flowing through. The transfer wall 17 also has a fence 18 inside, but need not be. The shaded area is the opening to the scavenging passage 9 and the inner wall surface of the cylinder. The above can be used in place of the scavenging passage 9 having a curved path also in FIG.

[0007]

According to the present invention, the liquid fuel adhering to the inner wall surface of the cylinder is collected and ejected from the scavenging passage 10 far from the exhaust port into the cylinder (formation of a rich mixture). Since the lean mixture is ejected from 9, the lean mixture is distributed near the exhaust port. When the rich mixture injected from the scavenging passage 10 far away from the exhaust port flows into the combustion chamber 3 and then reverses and flows out into the cylinder, it is directed in the direction opposite to the exhaust port by the orienting wall 3 '. The part going to is very small. Thus, even if the air-fuel mixture blows through, it is a lean mixture and the fuel itself has very little blow-through. As a result, fuel economy is significantly improved and exhaust gas is also purified.

[Brief description of the drawings]

FIG. 1 shows a two-stroke internal combustion engine according to the invention.

FIG. 2 is a schematic diagram showing a fuel chamber.

FIG. 3 is a diagram showing each embodiment of a two-cycle internal combustion engine according to the present invention.

[Explanation of symbols]

1 is a piston, 2 is a cylinder, 3 is a combustion chamber, 3 'is an orienting wall, 4 is a crank web, 5 is a crank chamber,
6 is a suction passage, 7 is a carburetor, 8 is an exhaust passage, 9 is a scavenging passage, 10 is a scavenging passage, 11 is an annular groove, 12 is a communication hole,
3 is a receiver, 14 is a shroud, 15 is an annular passage,
16 is a small hole, 17 is a transfer wall surface, and 18 is a fence.

Claims (2)

[Claims] In a crankcase compression type two-stroke internal combustion engine that sucks an air-fuel mixture into a crankcase, liquid fuel adhering to a cylinder inner wall surface is collected in an annular groove formed in the cylinder inner wall surface or the crankcase inner wall surface. The fuel is ejected into the cylinder from the scavenging passage far away from the exhaust port in the scavenging passage, and when the rich mixture formed by this constitution tries to flow out of the combustion chamber into the cylinder, the exhaust gas is exhausted. A two-stroke internal combustion engine, characterized in that an orienting wall oriented in a mouth direction is formed in a combustion chamber. 2. In a crankcase compression type two-stroke internal combustion engine that draws an air-fuel mixture into a crankcase, liquid fuel adhering to the inner wall surface of the cylinder is separately formed and collected by a receiver provided, and the liquid fuel is transferred to a scavenging passage. Of the rich air-fuel mixture formed by the scavenging passage far away from the exhaust port into the cylinder. A two-stroke internal combustion engine, wherein an orienting wall is formed in a combustion chamber.