JPS6332965B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention accommodates a crank web that connects connecting rods leading to pistons in a crank chamber at the bottom of an engine body, and supplies fuel and air from an air supply port opened in the crank chamber. The present invention relates to a lubricating oil guide device for a two-stroke engine that supplies lubricating oil together with an air-fuel mixture. Conventionally, in this type of engine, the lubricating oil contained in the air-fuel mixture collides with the wall of the air intake port, part of which becomes a wall flow and is separated from the air-fuel mixture flow, and remains in the form of a mist inside the crank chamber. The inflowing lubricating oil is also scattered on the circumferential surface and outer surface of the crank web, and most of it is scavenged without reaching the connection part with the connecting rod on the inner surface of the web, resulting in insufficient oil supply to the connection part, resulting in damage to the connection part. This is accompanied by the inconvenience of having to increase the amount of lubricating oil to ensure the lubricity of the parts.

In order to eliminate such inconveniences, the present invention provides a lubricating oil guide device that can guide lubricating oil to the joint between the web and the connecting rod without scattering the lubricating oil at locations where lubrication is not required, such as the circumferential surface or outer surface of the web. Its purpose is to extend onto the inner wall surface of the crank chamber into the gap between the skirt portion of the piston and the crank web when the piston is at the bottom dead center position, and to have its tip end contact the web. The tongue wall portion facing the sliding surface of the large end portion of the cooking stove and the large end portion of the cooking stove is formed continuously on the lower wall surface of the opening of the air supply passage. The present invention will be explained below with reference to the illustrated embodiments.

Referring to FIGS. 1 and 2, reference numeral 1 designates an engine body composed of an upper cylinder 1a and a crankcase 1b consisting of left and right halves of the lower cylinder 1a, and a crank chamber in the crankcase 1b. A pair of left and right crank webs 4, 4 integral with the crankshaft 3 are accommodated in the crankshaft 2, and a connecting rod 7 connected to the piston 6 is connected to a crank pin 5 that spans both webs 4, 4.
is pivoted at its lower large end 7a, and the cylinder insertion hole 1c at the upper end of the crankcase 1b.
An air intake port 10 that opens into the crank chamber 2 and communicates with an external air intake passage 8 via a reed valve 9 is formed on one side in the lateral direction of the air supply passage 8, and a mixture of fuel and air flows into the air intake passage 8. The lubricating oil pumped from the oil pump is mixed with the lubricating oil, and the lubricating oil is supplied to the crank chamber 2 along with the air-fuel mixture from the air supply port 10, thereby creating a side reed valve type two-stroke engine with a separate lubrication system as a whole. Configured. 11 in drawings
indicates a scavenging passage.

Although the above is not particularly different from the conventional one, according to the present invention, the skirt portion 6a of the piston 6 and the crank web 4 are formed on the inner wall surface of the crank chamber 2 when the piston 6 is at the bottom dead center position. A tongue wall portion 12 is formed continuously on the lower wall surface 10a of the air supply port 10, extending into the gap between the two, and having its tip facing the sliding surface between the crank web 4 and the large end 7a of the connecting rod 7. To explain this in more detail, in the embodiment shown in FIGS. 1 and 2, the tongue wall portion 12 integrally extends inward from the inner edge of the lower wall surface 10a of the air supply port 10. A tongue wall portion 12', which is substantially symmetrical to the tongue wall portion 12, is also formed at the entrance of the scavenging passage 11 formed at a position facing the air supply port 10.

Next, to explain the operation, as the piston 6 moves upward from the bottom dead center position, lubricating oil is supplied to the crank chamber 2 along with a mixture of fuel and air from the reed valve 9 through the air supply port 10. It is something that
At this time, the lubricating oil with a large specific gravity collides with the wall surface of the air supply port 10, and a part of it becomes a wall flow, but this wall flow is transmitted from the lower wall surface 10a to the tongue wall portion 12 continuous thereto. The lubricating oil that is guided into the opposing gap between the crank webs 4 and 4 and flows into the crank chamber 2 in the form of a mist along with the flow of the air-fuel mixture is also coated on the circumferential surface of the web 4 due to the presence of the tongue wall portion 12. The lubricating oil is guided to the center of the crank chamber 2 without being scattered and collides with the connecting rod 7, and the connecting portion between the web 4 and the connecting rod 7 is formed by the wall flow and the lubricating oil that collides with the connecting rod 7 and falls. That is, the sliding surface of the bearing part around the crank pin 5 and the large end 7a of the connecting rod 7 and the web 4 is lubricated.

In addition, during the scavenging stroke due to the downward movement of the piston 6 from the top dead center position, a part of the lubricating oil flowing into the scavenging passage 11 together with the air-fuel mixture collides with the wall surface of the passage 11 and becomes a wall flow and flows toward the crank chamber 2 side. In this case, if a tongue wall portion 12' is extended at the entrance of the passage 11 as in the above embodiment, this backflow lubricating oil can also be advantageously used to lubricate the connecting portion.

3 and 4 show other embodiments,
In this case, an air scavenging passage 11 is formed in the cylinder insertion hole 1c in a direction opposite to the rotation direction X of the crank web 4 with respect to an air intake port 10 formed on one side in the lateral direction. Lower wall surface 10 of
A tongue wall portion 12 is provided to extend along the circumferential direction of the insertion hole 1c so as to be continuous with each of the front and rear ends of the web 4. The tongue wall portion 12 extending in the portion A that generates the downward airflow is formed to be relatively long so as to reach the split surface of the crankcase 1b, and the wall surface flow of lubricating oil from the air supply port 10 flows through the tongue wall portion 12. The connecting portion of the web 4 and the conrod 7 located on the split surface are guided along the connecting rod 7.

As described above, according to the present invention, the inner wall surface of the crank chamber 2 extends into the space between the skirt portion of the piston 6 and the crank web 4 when the piston 6 is at the bottom dead center position, and its tip end Since the tongue wall portion 12 facing the sliding surface of the web 4 and the large end portion 7a of the cooking rod is continuously formed on the lower wall surface of the air supply port 10, the air-fuel mixture at the air supply port 10 is The lubricating oil that has flowed in at the same time is guided by the tongue wall 12 that is continuous with the lower wall surface of the port 10 and is supplied toward the sliding surface between the connecting rod large end 7a and the crank web 4. The proportion of lubricating oil that is supplied to the large end 7a without scattering on the circumferential surface of the large end 7a increases, and even if the amount of lubricating oil supplied is reduced, the lubricity of the large end 7a can be ensured.

[Brief explanation of the drawing]

Fig. 1 is a cutaway front view of an example of a two-stroke engine equipped with the device of the present invention, and Fig. 2 is a - of Fig. 1.
FIG. 3 is a cross-sectional side view of another embodiment, and FIG. 4 is a plan view taken along the line -- of FIG. 3. 1...Engine body, 2...Crank chamber, 4...
...Crank web, 6...Piston, 7...Conrod, 10...Air supply port 10a...Lower wall surface,
12... tongue wall part.

Claims (1)

[Claims] 1 A crank web connecting a conrod connected to a piston is housed in a crank chamber at the bottom of the engine body, and lubricating oil is supplied together with a mixture of fuel and air from an air supply port opened in the crank chamber. In the two-stroke engine,
On the inner wall surface of the crank chamber, the piston extends into the space between the skirt portion of the piston and the web when the piston is at the bottom dead center position, and its tip portion is the large end of the web and the connecting rod. A guide device for lubricating oil in a two-stroke engine, characterized in that a tongue wall portion facing a sliding surface with the intake port is formed continuously on a lower wall surface of the air intake port.