Makita Corporation

Masaki Kurimoto

Masaki Sugiyama

Toshihiro Tomita

Hiroshi Kubota

Yuji Takahashi

Yuki Nakamura

Tetsuya Hasegawa

Masayuki Iwase

A four-stroke engine for a working machine with a rod is provided, where a tool is attached to one end of the rod in a longitudinal direction and the four-stroke engine is fixed to the other end of the rod in use. The four-stroke engine includes: an oil circulation pathway; and a gas-liquid separating chamber configured to separate oil from blowby gas. The gas-liquid separating chamber includes: an inflow part into which the blowby gas is introduced from the oil circulation pathway; oil discharge parts configured to flow the oil separated from the blowby gas back to the oil circulation pathway; and a blowby gas discharge part configured to discharge the blowby gas not containing oil mist from the gas-liquid separating chamber and supplies the blowby gas to an intake passageway to a combustion chamber.

Four-stroke engine

A lubrication apparatus for a four-stroke engine includes an oil tank, a supply passageway having an opening to supply oil mist from the oil tank to driving parts, the opening being provided in the oil tank. A partition is provided between the opening and a side wall of the oil tank, the partition being formed by partition plate members so as to divide an inside of the oil tank into an inner area and an outer area. The inner area includes the opening, and the outer area is defined between the inner area and the side wall. Oil can freely move between the inner area and the outer area, and the opening is placed in a position above a surface of the oil accumulated in the oil tank even when the four-stroke engine is tilted in every direction.

Lubrication apparatus for four-stroke engine

A lubrication apparatus for a four-stroke engine that prevents lubrication failure from occurring around the crankshaft and reliably prevents oil from remaining in a valve operating chamber includes: an intake part positioned below the level of an oil A in an oil reservoir even if the oil reservoir is tilted and the level of the oil A changes; an oil feeding passageway that sucks up the oil A from the intake part and supplies the oil A to the crank chamber; and an direct passageway that allows communication between a valve operating chamber and a crank chamber when a negative pressure is created in the crank chamber. Open end parts of the oil feeding passageway and the direct passageway which are open in the crank chamber are provided to open as the piston moves from a position near the top dead center to the top dead center.

A lubrication system for a portable four-stroke engine includes an opening end of the breather passage is disposed at substantially a center of a valve-operating chamber, and the valve-operating chamber is formed by attaching a valve-operating chamber cover. An inner cover is attached to an inner surface of the valve-operating chamber cover so as to be provided along and in contact with the inner surface of the valve-operating chamber cover. A suction passage is formed as a gap between the circumferential edge of the top plate portion and the inner cover. Three or more suction tubes that are in communication with the suction passage are provided in the inner cover, each of the suction tubes having an opening end. At least one of the opening ends of the suction tubes is provided lower than the opening end of the breather passage in an attitude of the engine during use.

Lubrication system for portable four-stroke engine

A lubrication system for a four cycle engine that lubricates the valve mechanism with the oil mist of the concentration, lowered by the liquefying means. The lubrication system has an oil feeding passage for connecting an oil reservoir with the crank chamber and sending the oil retained in liquid form in the oil reservoir to the crank chamber under a negative pressure of the crank chamber, a communication passage for connecting the crank chamber with the oil reservoir and sending oil mist generated in the crank chamber to the oil reservoir when under a positive pressure of the crank chamber, liquefying means in the oil reservoir for liquefying the oil mist sent from the communication passage to the oil reservoir to decrease the concentration of the oil mist, and a supply passage for supplying the oil mist from the oil reservoir to the valve operating chamber through the liquefying means.

Growing community of inventors

Numazu, Japan

Masaki Kurimoto