Kioritz Corporation

Yumin Liu

Noboru Nagai

Tsuneo Araki

Yukio Sawadate

Yoshiaki Nagao

Masahiko Iizuka

The present invention provides an air-cooled four-stroke internal combustion engine capable of achieving a high degree of cooling. The present invention is directed to an air-cooled four-stroke internal combustion engine including a crankshaft and a fan rotor rotatably driven by the crankshaft to generate cooling air for cooling the engine. The engine comprises an oil pan disposed below the crankshaft. A space formed below the oil pan extends in the axial direction of the crankshaft along the lower surface of the oil pan and allows a cooling air to pass therethrough. An upstream portion of the lower surface is inclined upward, toward the upstream, in a vertical section taken along the axis of the crankshaft to receive the cooling air therein.

Air-cooled four-stroke internal combustion engine

An internal combustion engine capable of optimizing the amount of oil in the crank chamber with a simplified structure of lubrication system, in which a U-shaped oil reservoir is formed surrounding and adjacent to a crank chamber. At least one small hole is formed on a partition wall which separates the oil reservoir and the crank chamber from each other so that the crank chamber may always communicate with the oil reservoir through the small hole. Due to a flow resistance in the small hole, a pressure Po in the oil reservoir changes following a change of pressure Pc in the crank chamber with some delay, and where the pressure difference between the oil reservoir and the crank chamber caused by a delay in the change of the pressure Po in the oil reservoir, results in the introduction of the oil in the oil reservoir into the crank chamber. It further allows excessive oil in the crank chamber to be circulated back into the oil reservoir.

Internal combustion engine

A cooling system for an OHC type four-stroke cycle internal combustion engine having a valve chamber lubricated by oil mist. The system includes an accommodating space accommodating a transmission mechanism, a blower fan rotatably driven by a crankshaft, and a cooling air channel extending between a combustion chamber and the valve chamber disposed above the combustion chamber. The cooling air channel includes a primary air channel formed between intake and exhaust ports and extends toward a spark plug located on the downstream side of the cooling air channel. The cooling air channel also includes an air guide channel for guiding the air to an upstream inlet of the primary air channel and is defined by a wall which faces the upstream inlet of the primary air channel and extends laterally. The wall extends vertically in the accommodating space and is formed with an oil mist passage extending vertically therein.

Cooling system for four-stroke cycle internal combustion engine

The present invention relates to a four-stroke cycle internal combustion engine in which lubrication oil is atomized to generate oil mist so as to lubricate an internal mechanism of the engine with the oil mist. The four-stroke cycle internal combustion engine includes an oil-mist breather in fluid communication with a fuel tank of the engine. Any oil mist remaining after the lubrication of the internal mechanism is discharged into the fuel tank through the oil-mist breather Since no oil mist remains in the oil-mist breather the air filter of the engine is not contained by the oil mist.

Four-stroke cycle internal combustion engine

An air-preintroduction type two-stroke internal combustion engine which is capable of minimizing the quantity of blow-by, thus making it possible to improve the fuel consumption and to reduce the content of poisonous components in the exhaust gas, and is also capable of reasonably and compactly arranging the peripheral components of engine, thereby making it possible to reduce the number of parts, to lighten the weight thereof, to save the manufacturing cost thereof, and to simplify the working and assembling thereof. Specifically, this internal combustion engine is characterized in that an air inlet passageway for introducing air into the scavenging passageways is provided inside a wall portion of the cylinder.

Two-stroke internal combustion engine

A four-stroke cycle internal combustion engine in which an oil reservoir for storing lubricating oil is arranged below a crank chamber housing a crankshaft, and oil mist formed in the oil reservoir is supplied to the interior of the crank chamber and to a valve chamber through an oil mist passage for providing fluid communication between the oil reservoir and the valve chamber. The oil mist passage includes a pre-separation oil mist passage section formed in the crankshaft, a cylindrical centrifugal-separation chamber surrounding the outer-periphery of the crankshaft, a post-separation oil mist passage section extending from the centrifugal-separation chamber in the opposite direction of the rotational direction of the crankshaft and in fluid communication with the valve chamber, and an oil return passage providing fluid communication between the centrifugal-separation chamber and the oil reservoir.

In a compression stroke and an exhaust stroke, a part of a mixture in a downstream intake passage is introduced through a branch intake passage into a crank chamber . The mixture introduced into the crank chamber flows into a valve chamber 16 during the expansion stroke and the intake stroke. From which it flows back to an intake port through a circulation passage , and is eventually charged into a combustion chamber during the intake stroke. As the mixture passes through a first communicating passage which allows fluid communication between the crank chamber and the valve chamber , a gasoline component which is vaporized with comparative easy is vaporized by a heat released from a cylinder block so that the mixture is separated into the lubricating oil and gasoline components.

The present invention relates to a four-stroke cycle internal combustion engine which is adapted to lubricate the inside of the engine using a mixed fuel composed of fuel and lubricant. The four-stroke cycle internal combustion engine includes a combustion chamber; an intake port which opens toward the combustion chamber; an air intake passage communicating with the intake port, the air intake passage having a downstream side air intake passage which is located on a downstream side of a fuel supply device for supplying the mixed fuel to the air intake passage; a crank shaft; a crank chamber accommodating the crank shaft; a branch passage branching off from the air intake passage for communicating the downstream side air intake passage of the air intake passage with the crank chamber; a valve system; a valve chamber accommodating the valve system; a communication passage for communicating the crank chamber with the valve chamber; a circulation passage for communicating the valve chamber with the air intake passage; and a valve disposed in the branch passage for opening and closing the branch passage.

An object of the present invention is to provide an improved lubricating method and device for the internal combustion engine, which allows the engine to be lubricated by taking advantage of engine vibration without using other power source. The lubricating device includes a crankcase separated into a crank chamber and an oil reservoir by a partition wall. The partition wall has an opening provided with a wire net for covering the opening. A coil spring is suspended within the oil reservoir so as to form a U-shape. During operation, an engine vibration induces a vibration of the coil spring, and the oscillating coil spring agitates and/or splashes up an engine oil contained in the oil reservoir, and whereby an entire oil surface is ruffled. The engine oil introduced into the crank chamber impinges on a crankshaft and finer droplets or oil mist is formed to thereby lubricate the crankshaft and other engine components.

Lubricating method and device of internal combustion engine

The four-stroke cycle internal combustion engine for portable working machines, which employs a toothed belt in the power transmission mechanism thereof, is disclosed. There is provided an OHC type four-stroke cycle internal combustion engine including a power transmission mechanism disposed vertically along a cylinder portion for transmitting the rotation of a crankshaft to a camshaft, wherein the power transmission mechanism comprises intermediate transmission members linked to the camshaft through a toothed belt and a rotation speed transmission member for reducing the rotation speed from the crankshaft and for transmitting it to the intermediate transmission members.

A four-stroke cycle internal combustion engine comprises a connecting rod which has an oil dipper at a big-end thereof, a crankcase, a partition wall which surrounds the connecting rod to provide a separation between the crankcase and an oil reservoir and an outer wall which is outward of and surrounds the partition wall and is connected to the partition wall at upper ends thereof so as to define the oil reservoir below the crankcase. A slit is formed in the partition wall below the connecting rod to allow the oil dipper to protrude into and be withdrawn from the oil reservoir to splash oil in the oil reservoir for lubrication by the oil dipper through a swinging motion of the connecting rod. The depth of the oil reservoir is shallower at least in a part of an outer edge area thereof than that below the oil dipper so that a tip of the oil dipper reaches the oil level even when the oil flows into the outer edge area of the oil reservoir.

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Fussa, Japan

Yumin Liu