Lubrication structure for four-stroke engine

Abstract

A lubrication structure for a four-stroke engine to lubricate driving parts by supplying oil stored in an oil tank provided separately from a crank chamber, using pressure fluctuation in the crank chamber, includes: a first circulating route to supply the oil from the oil tank to the crank chamber and return oil mist generated in the crank chamber to the oil tank; a second circulating route to supply the oil mist from the oil tank to a valve operating mechanism and return to the oil tank; a discharge passageway to discharge blowby gas contained during circulation of the oil from the second circulating route to a combustion chamber; and a partition wall to separate between the crank chamber and the oil tank. A central part of the partition wall is located vertically above a surface of the oil stored in the oil tank even if an engine body is tilted.

Description

technical field [0001] The present invention relates to a lubricating structure for a four-stroke engine, and more particularly, to a lubricating structure for a four-stroke engine mounted in a portable working machine such as a brush cutter and a backpack blower. Background technique [0002] Conventionally, since the lubrication structure of the four-stroke engine mounted in the portable work machine is inclined at various angles when the operator performs work, the lubrication structure is required to reliably lubricate the driving parts of the engine regardless of the posture. [0003] As a lubricating structure for a four-stroke engine mounted in a portable working machine, for example, Patent Document 1 discloses a lubricating device for a four-stroke engine in which a lubricating oil reservoir is formed to substantially surround the outer periphery of the crank chamber. room. [0004] Patent Document 1: Japanese Patent Application Laid-Open No. 8-260926 [0005] Th...

AI Technical Summary

Problems solved by technology

[0009] In this way, in the invention described in Patent Document 1, since excess lubricating oil is supplied to the valve train, there is a technical disadvantage that the lubricating oil is discharged into the combustion chamber and the lubricating oil is consumed in a short time. question

[0010] Therefore, since the lubricating oil is consumed in a short period of time, the replenishment period of the lubricating oil is shortened, and if the replenishment of the lubricating oil is neglected, it will cause poor lubrication.

In addition, since lubricating oil is discharged from the combustion chamber to the outside in an unburned state, it has an adverse effect on the environment

Images