An engine includes a cylinder, a rocker chamber, an air filter, a crankcase and a rocker chamber cover, wherein the rocker chamber cover is disposed above the cylinder. The engine further includes a cover plate, wherein the cover plate is located at the top of the rocker chamber cover, and the rocker chamber cover and the cover plate are spliced to form a separation cavity and a connection channel. According to the engine provided by the invention, the top structure of the rocker chamber is re-designed and the top space of the rocker chamber is sufficiently used so as to achieve the objects of optimizing a lubricating system and reducing emission, as well as reducing the manufacturing cost and difficulty.

An engine includes a crankcase defining a crankcase space, a first shaft disposed at least partially within the crankcase and supported for rotation by the crankcase, and an oil pump coupled to the first shaft and operable to draw low pressure oil from the crankcase and discharge a flow of high pressure oil. A pressure relief path is positioned to selectively receive a portion of the flow of high pressure oil and a pressure relief assembly is coupled to the pressure relief path and is arranged to spray the portion of the high pressure flow that passes through the pressure relief passage against an interior surface of the crankcase.

An engine includes a crankcase defining a crankcase space, a first shaft disposed at least partially within the crankcase and supported for rotation by the crankcase, and an oil pump coupled to the first shaft and operable to draw low pressure oil from the crankcase and discharge a flow of high pressure oil. A pressure relief path is positioned to selectively receive a portion of the flow of high pressure oil and a pressure relief assembly is coupled to the pressure relief path and is arranged to spray the portion of the high pressure flow that passes through the pressure relief passage against an interior surface of the crankcase.

The present invention discloses an engine oil pan, which includes a cylinder block, wherein a plurality of arc-shaped grooves are disposed on the second end surface of the cylinder block along the axial direction of a crank shaft; the arc-shaped grooves form arc-shaped bulges in a sunk portion on the first end surface of the cylinder block; the arc-shaped bulges divide the sunk portion into first space and second space; a platform is disposed inside the sunk portion of the cylinder block; and the height of the platform is lower than the height of the arc-shaped bulges. The technical solution employed by the present invention enables lubricating oil in the engine oil pan to flow more effectively, and enables the lubricating oil in the oil pan to be utilized more effectively when the engine is used in any position.

The present invention discloses an engine oil pan, which includes a cylinder block, wherein a plurality of arc-shaped grooves are disposed on the second end surface of the cylinder block along the axial direction of a crank shaft; the arc-shaped grooves form arc-shaped bulges in a sunk portion on the first end surface of the cylinder block; the arc-shaped bulges divide the sunk portion into first space and second space; a platform is disposed inside the sunk portion of the cylinder block; and the height of the platform is lower than the height of the arc-shaped bulges. The technical solution employed by the present invention enables lubricating oil in the engine oil pan to flow more effectively, and enables the lubricating oil in the oil pan to be utilized more effectively when the engine is used in any position.

A mixture-lubricated four stroke engine has a cylinder in which a combustion chamber is formed. The combustion chamber is delimited by a piston which is mounted movably in the cylinder. The engine has an intake channel which discharges into the combustion chamber via an inlet opening controlled by an inlet valve. A mixture formation unit includes at least one fuel opening which discharges into the intake channel. For the lubrication of the crankcase interior, a flow connection connects the intake channel to the crankcase interior via a connecting opening which discharges into the intake channel downstream of the mixture formation unit. The fuel quantity is controlled by a fuel valve. A control unit is configured to activate the fuel valve in a manner dependent on the position of the crankshaft such that the fuel valve is opened at least also during a part of the compression stroke.

A mixture-lubricated four stroke engine has a cylinder in which a combustion chamber is formed. The combustion chamber is delimited by a piston which is mounted movably in the cylinder. The engine has an intake channel which discharges into the combustion chamber via an inlet opening controlled by an inlet valve. A mixture formation unit includes at least one fuel opening which discharges into the intake channel. For the lubrication of the crankcase interior, a flow connection connects the intake channel to the crankcase interior via a connecting opening which discharges into the intake channel downstream of the mixture formation unit. The fuel quantity is controlled by a fuel valve. A control unit is configured to activate the fuel valve in a manner dependent on the position of the crankshaft such that the fuel valve is opened at least also during a part of the compression stroke.

An oil treatment system for an internal combustion engine in one implementation includes an elongated dipstick tube defining a tube axis and a first flow passageway, a housing arranged on the dipstick tube and defining an internal cavity, an oil treatment apparatus disposed in the internal cavity, and a retainer coupled to the housing. The retainer may have a cylindrical body comprising an elongated first flow protuberance insertably received through the oil treatment apparatus to establish fluid communication between the oil treatment apparatus and the first flow passageway of the dipstick tube. The retainer comprises a cavity through which oil may be added directly to the first flow passageway of the dipstick which may be fluidly coupled to an oil sump of the engine. The oil treatment apparatus may be an oil filter. An oil treatment additive may optionally be added to the housing.

An oil treatment system for an internal combustion engine in one implementation includes an elongated dipstick tube defining a tube axis and a first flow passageway, a housing arranged on the dipstick tube and defining an internal cavity, an oil treatment apparatus disposed in the internal cavity, and a retainer coupled to the housing. The retainer may have a cylindrical body comprising an elongated first flow protuberance insertably received through the oil treatment apparatus to establish fluid communication between the oil treatment apparatus and the first flow passageway of the dipstick tube. The retainer comprises a cavity through which oil may be added directly to the first flow passageway of the dipstick which may be fluidly coupled to an oil sump of the engine. The oil treatment apparatus may be an oil filter. An oil treatment additive may optionally be added to the housing.

The present disclosure is directed towards an engine assembly comprising a crankcase, a crankshaft, a lubrication system and fluid guide arrangement. During rotation the crankshaft is configured to drive a crankcase fluid flow in a crankcase chamber. The lubrication system comprises a lubricant drain for a drain fluid flow therethrough extending to a drain aperture at the crankcase chamber. The fluid guide arrangement is located adjacent or in proximity to the drain aperture. The fluid guide arrangement is configured for guiding crankcase fluid flow away from the drain aperture and/or for reducing the pressure of the crankcase fluid flow past the drain aperture, such that drain fluid flows from the lubricant drain.