Abstract: 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.

Abstract: 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.

Abstract: 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 include pre-separation oil mist passage section formed in the crankshaft, and having one end in fluid communication with the oil reservoir and the other end opened on the radial outer-periphery of the crankshaft; a cylindrical centrifugal-separation chamber surrounding the outer-periphery of the crankshaft on which the other end is opened; and 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A four-stroke cycle internal combustion engine is adapted to deliver oil mist from an oil reservoir to a cam chamber together with blow-by gas. It has an oil reservoir, a cam chamber, an oil dipper formed on a connecting rod for agitating oil in the oil reservoir to generate oil mist, a carburetor, and an oil separator provided between the cam chamber and the carburetor and for separating oil contained in oil mist from blow-by gas. The oil separator has a vertically extending first passage which communicates with the cam chamber at an upper end and communicates with the oil reservoir at a lower end and a second passage which communicates with the lower end of the first passage at one end and communicates with a venturi of the carburetor at the other end.

Abstract: In a two-stroke internal combustion engine, output power is increased and total hydrocarbon (THC) exhaust is decreased as a result of small structural changes. An exhaust port and scavenging ports are configured and disposed such that they are open in a reduced period of the combustion cycle.

Abstract: In a two-stroke internal combustion engine, total hydrocarbon (THC) exhaust is decreased as a result of small structural changes and without loss of output power. A Schnurle scavenging-type combustion chamber has a hemispherical main surface and an annular skirt-like squish band, and a spark plug is disposed for a spark point to be substantially at the center of the combustion chamber. The squish band has minimized width.

Abstract: A muffler for internal combustion engines is formed of vertically separable body sections so that the sound absorbing and filter members may be accessed easily for replacement and/or cleaning.

Abstract: A muffler with a catalyst A muffler closure is detachably attached to the muffler body of the muffler. A thermal insulation acoustic material layer and a catalyst layer are mounted to an inner surface of muffler closure through a porous holding plate along exhaust gas passage.

Abstract: An internal combustion engine exhaust muffler formed to be dividable and integratable wherein an exhaust gas introducing tube and a pair of supporting pillars positioned substantially parallelly on both sides of the exhaust gas introducing tube are arranged within the exhaust muffler and a tubular member holding a cloth-like catalyst between holding screens is deformed to be substantially elliptically tubular and is hung over the pair of supporting pillars so as to enclose the exhaust gas introducing tube.

Abstract: An exhaust device for a working machine in which a mixing tubular member is disposed opposite to an outlet opening of the muffler through a space interposed between them, and an air-flow passage is provided to introduce a portion of pressurized air from a blower into the inside of an air guide wall on the outer periphery of the outlet opening.