Husqvarna Outdoor Products Inc.

Shiro Kawamoto

Andrew L Curtis

Derek J Egerstaffer

Edward Mikell Wallace

Hugh B McCullough

A four-stroke engine employs engine vibration for lubricating engine components. The engine vibration induces a ripple in a surface portion of the oil in an oil reservoir, which is located within a crankcase of the engine. The oil ripple causes misting of the oil, which lubricates exposed engine components. Providing a crankcase wall thickness of about 1.5 mm or less can increase the engine vibration. Alternatively, a clearance area located within the crankcase can be decreased to facilitate contact of the oil surface ripple with a counterweight, thereby splashing the oil onto exposed engine components. Vibration of the engine can be further increased by coupling a vibration plate or spring to a portion of the crankcase.

Four-stroke engine system

A four-stroke engine includes a piston cylinder, and a piston located in the cylinder and movable within the cylinder. The engine includes a crankcase attached to the cylinder, the piston providing a separation boundary of a combustion portion of the cylinder from the crank case, and a crank member located within the crankcase and operatively connected to the piston. The engine including components for operating the engine in a four-stroke sequence, and components for introducing a fuel mixture into the combustion portion of the cylinder, the fuel mixture having an ability to lubricate. The engine including a construction and/or configuration for promoting passage of a portion of the mixture from the combustion portion of the cylinder to the crankcase in a sufficient amount to provide lubrication within the crankcase without reservoir lubricant in the crankcase.

Four-stroke engine lubricated by fuel mixture

A power tool includes vibration isolation material positioned between an engine shroud and a drive shaft housing. The vibration isolation material isolates the drive shaft housing from engine vibration for radial, axial, and torsional movement without utilizing intermediate components.

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Texarkana, AR, United States of America

Shiro Kawamoto