JPH07656Y2 - Lubricator for 2-cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a two-stroke gasoline engine.

[Conventional technology]

FIG. 4 shows an example of a conventional crank compression type two-stroke gasoline engine using mixed oil fuel, where 1 is a crankcase, 2 is a piston, 3 is a connecting rod,
4 is a cylinder, 5 is a cylinder head, 6 is a piston pin, 8 is a crank pin, 9 is a crank web, 20 is a carburetor, 21 is a muffler, 23 is an intake hole, and 24 is an exhaust port. In this engine, a mixed oil in which lubricating oil is mixed in gasoline in a predetermined ratio is used, and the mixed oil is supplied to the engine together with fuel through a carburetor.

The lubricating oil in the mixed oil discharged from the carburetor 20 exists in the form of a mist or a liquid film in the suction hole 23 and the crankcase 1, but the mist-like one rides on the flow of air during the scavenging stroke. It flows into the combustion chamber and is discharged from the exhaust port 24 after the combustion process.

Next, the lubrication action of the mixed fuel will be described.

The mist-like lubricating oil directly reaches the sliding part and contributes to lubrication, or the gasoline component evaporates while flowing by the flow of air, and the lubricating oil component mainly adheres to the wall surface to form a liquid film. The portion of the liquid film that has diffused and reached the sliding portion or rotating portion is used for lubrication. Since the liquid film inside the crankcase 1 moves violently, it does not stay for a certain amount or more, and the excess lubricating oil is carried away by the moving part or by the gas flow and becomes droplets or mist again and flows with the air. To do. As described above, in the conventional two-cycle engine lubrication system, the lubricating oil is not positively supplied to the necessary places, but is supplied by the air flow and liquid film diffusion inside the crankcase. Only the part reaches the necessary part and performs the lubricating action.

[Problems to be solved by the invention]

The conventional lubrication system has a drawback that the lubricating oil reaches the portion where the air flow is strong, while the lubricating oil does not reach the portion where there is no air flow. For example, in FIG. 4, the lubricating oil does not easily reach the piston pin portion 6 inside the piston, and in many cases, a countermeasure is taken to increase the lubricating oil mixing ratio of the mixed fuel. However, if such measures are taken, there is a drawback that the consumption of lubricating oil increases and the combustion chamber is contaminated, and smoke in the exhaust gas increases. That is, since the lubricating oil hardly burns, it becomes a carbon medium and accumulates in the combustion chamber, deposits inside the spark plug, and produces white smoke or blue smoke when discharged together with the exhaust gas.

Further, as a measure against the insufficient supply of lubricating oil to the piston pin portion as described above, an oil scraper (raised) is attached to the large end portion of the connecting rod as shown in the invention of Japanese Utility Model Laid-Open No. 60-110613. There is a type in which the oil scraper scrapes up the lubricating oil that has accumulated in the lower part of the crankcase, and splashes it on the piston pin part with this oil scraper. However, in this case, a member different from the connecting rod is bolted to the large end of the connecting rod where the high-speed rotation motion and the reciprocating motion are combined,
There is a risk of oil scraper falling off due to insufficient bolt rotation prevention. Further, since an oil scraper, a bolt for mounting the oil scraper, a member such as a rotation washer, etc. are required, the number of parts is increased. Accordingly, it is an object of the present invention to provide a lubrication device for a two-cycle engine capable of reducing the consumption of lubricating oil and generating a carbon medium in a combustion chamber and reducing white smoke in exhaust gas.

[Means and actions for solving problems]

In the crankcase compression type two-cycle gasoline engine, the present invention positively feeds the lubricating oil to the piston pin portion where the lubricating oil is hard to reach. That is, the lubricating oil mist existing in the crankcase becomes a liquid film flow because the lubricating oil adheres to the crankcase wall surface due to the vaporization of the gasoline and the centrifugal action due to the strong swirling flow. Even if a part of gasoline adheres to the crankcase, the high temperature of the crankcase evaporates and the lubricating oil mainly remains on the wall surface. The liquid film flow containing the lubricating oil as a main component is accumulated in the groove 31 provided on the wall surface of the crankcase 1. Lubricating oil stored in the groove 31 is scraped up by one projection 32 provided on the crank web 9 and is supplied to the piston pin 6 at the piston 2 position near the bottom dead center.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

In the figure, a crankshaft 7 is axially supported in a crankcase 1 via a ball bearing, and a piston 2 is fitted in a cylinder 4. The piston 2 and the crankshaft 7 are connected to a piston pin 6 and a connecting rod 3 Then, they are connected via the crank pin 8. The engine is a crankcase compression type 2-cycle gasoline engine, and when the piston 2 rises, a negative pressure is generated inside the crankcase 1 and
A mixture of fuel and air is sucked from 23 through the carburetor 20. Lubricating oil is preliminarily mixed in the gasoline fuel at a certain ratio, and the lubricating oil is supplied to each part of the engine together with the flow of fresh air.

In the engine of the present invention, the outer surface of the crank web 9 is chamfered symmetrically as shown in FIG. 1, and the inner wall of the crankcase 1 is also tapered corresponding to this shape. Further, on the inner wall of the crank case corresponding to the maximum diameter of the crank web 9, a circumferential groove 31 concentric with the rotating shaft, that is, the crank shaft 7, is cut. Further, a protrusion 32 to be inserted into the groove 31 is provided at one place on the outer circumference of the crank web 9. The position where the protrusion 32 is provided is set so as to pass just through the upper end portion 33 of the crankcase groove 31 when the piston 2 is at the position before and after the bottom dead center.
At the upper end of the crankcase groove 31, a part of the inner wall surface that is transferred from the crankcase 1 to the cylinder portion is cut out so that the groove end is slightly convex as shown in FIG.

Next, the operation of the above embodiment will be described.

The mist of the lubricating oil introduced into the crankcase 1 adheres to the inner surface of the crankcase to form a liquid film. The gasoline content adhering to the crankcase 1 is gasified and introduced into the combustion chamber due to the high temperature wall surface. The liquid film attached to the inner surface of the crankcase is affected by the rotation of the crank web 9 and becomes a liquid film flow along the rotation direction. Since the inner wall surface of the crankcase is formed in a tapered shape, the liquid film flow is directed in the direction of the larger diameter and eventually flows into the groove 31 formed in the portion.
Lubricating oil accumulated in the groove 31 is forcibly conveyed in the rotation direction in the groove 31 by the protrusion 32 of the crank web 9, and the crankcase groove
The upper end 33 of 31 no longer has a guide, so that the lubricating oil is tangentially discharged as shown in FIG. As a result, the lubricating oil is scattered toward the inside of the piston near the bottom dead center and reaches the piston pin portion.

[Effect of device]

Since the lubrication device for a two-cycle engine according to the present invention is configured as described above, the protrusion of the crank web carries the lubricating oil accumulated in the groove of the crankcase along the groove, and at the portion past the upper end of the groove. By scattering toward the piston, the lubrication of the piston member such as the piston pin is promoted, the mixed oil component can be lowered, and the consumption amount of the lubricating oil can be reduced. Along with this, the production of carbon medium in the combustion chamber is suppressed, and the white smoke in the exhaust gas is reduced. Furthermore, since a protrusion that splashes the oil in the crankcase toward the piston is formed integrally with the crank web, there is no risk of falling accidents like conventional oil scrapers, and high reliability can be maintained. At the same time, the number of parts is reduced.

[Brief description of drawings]

1 to 3 relate to the present invention. FIG. 1 is a front sectional view, FIG. 2 is a side sectional view, FIG. 3 is an operation explanatory view, and FIG. is there. 1 ... Crank case, 2 ... Piston, 6 ... Piston pin, Crank shaft, 9 ... Crank web, 31 ... Groove, 32 ... Protrusion.

Continuation of front page (72) Masaaki Nakachi 1-1, Atsunoura-machi, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Research Institute (56) References: 60-110613 (JP, U) -15893 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. A crankcase compression type two-cycle gasoline engine, wherein an inner wall of the crankcase is formed in a cylindrical shape centering on a rotation axis of a crankshaft, and the rotation is carried out along an inner peripheral surface of the inner wall of the crankcase. A groove concentric with the shaft center is formed, and a protrusion to be inserted into the groove is provided at one location on the outer circumference of the crown web so that the protrusion passes through the upper end of the groove at a position near the bottom dead center of the piston. Lubricating device for a two-cycle engine configured in.