Lubrication structure for four-stroke engine
Inactive Publication Date: 2012-03-15
MAKITA CORP
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Benefits of technology
[0011]It is therefore an advantage of an aspect of the present invention to provide a lubrication structure for a four-stroke engine that can prevent oil from being consumed for a short period of time by lubricating a crank chamber having a crank axle and a valve operating mechanism, with respective appropriate amount of oil.
Problems solved by technology
However, the above-described patent document discloses a configuration where oil mist is supplied from a crank chamber having a crank axle to the valve operating mechanism without adjusting the concentration of the oil mist.
In this way, the configuration disclosed in the above-described patent document has a technical problem that oil is oversupplied to the valve operating chamber, and therefore extra oil is discharged to the combustion chamber, so that oil is consumed in a short period of time.
Therefore, oil consumption for a short period of time causes the period of time over which oil is refilled until the next time, to be shortened, and therefore, if refilling of oil is neglected, lubrication trouble may occur.
In addition, unburned oil is discharged from the combustion chamber to the outside, and this may cause environmental damage.
Method used
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Embodiment Construction
[0044]A lubrication structure for a four-stroke engine 30 according to the present embodiment lubricates driving parts by supplying oil stored in an oil tank 55 provided separately from a crank chamber 35, using pressure fluctuation in the crank chamber 35 due to the reciprocating motion of a piston 34.
[0045]Now, an embodiment of the present invention will be described in detail with reference to the drawings. First, the configuration of the four-stroke engine 30 according to the present embodiment will be explained with reference to FIG. 1A, FIG. 1B and FIG. 2. FIG. 1A is a perspective view schematically showing the configuration of the four-stroke engine 30 according to one embodiment of the present invention; FIG. 1B is a plan view schematically showing the configuration of the four-stroke engine 30 according to one embodiment of the present invention; and FIG. 2 is a cross sectional view schematically showing the four-stroke engine taken along I-I′ line shown in FIG. 1B.
[0046]As...
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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
BACKGROUND[0001]1. Field of the Invention[0002]The present invention relates to a lubrication structure for a four-stroke engine, and more specifically, to a lubrication structure for a four-stroke engine mounted in a portable working machine such as a brush cutter and a backpack blower.[0003]2. Description of the Related Art[0004]Conventionally, a lubrication structure for a four-stroke engine mounted in a portable working machine has been required to reliably lubricate driving parts in an engine whatever postures the working machine takes, because the working machine is tilted at various angles in use.[0005]A lubrication structure for a four-stroke engine mounted in a portable working machine is disclosed, for example, in Japanese Patent Application Laid-Open Publication No. HEI8-260926, which includes an oil storage chamber enclosing substantially the circumference of a crank chamber.[0006]Generally, a lubrication structure for a four-stroke engine needs a larger amount of oil in...
Claims
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Patent Timeline
Login to View More IPC IPC(8): F01M1/04
CPCF01M1/04F16N7/32F01M13/025F01M11/065
Inventor SUGIYAMA, MASAKIHASEGAWA, TETSUYA
Owner MAKITA CORP