Abstract: An engine body includes a crankcase with a crank chamber therein, a cylinder block attached to the crankcase, and a breather passage which selectively permits fluid communication between the crank chamber and an area outside of the crank chamber. The engine body includes a one-way valve between the crank chamber and the breather passage, which allows a one-way flow of gases from the crank chamber to the breather passage. The one-way valve is pressure-operated and is operatively attached to a side wall of the engine body proximate a cylinder sleeve. The one-way valve may be mounted in a mounting window in a side wall of the crankcase, and a timing chamber may function as the breather passage. In an illustrative embodiment, the one-way valve includes a base plate having a valve hole formed therein, and a flexible reed valve plate with one end affixed to the base plate.

Abstract: An engine body includes a crankcase with a crank chamber therein, a cylinder block attached to the crankcase, and a breather passage which selectively permits fluid communication between the crank chamber and an area outside of the crank chamber. The engine body includes a one-way valve between the crank chamber and the breather passage, which allows a one-way flow of gases from the crank chamber to the breather passage. The one-way valve is pressure-operated and is operatively attached to a side wall of the engine body proximate a cylinder sleeve. The one-way valve may be mounted in a mounting window in a side wall of the crankcase, and a timing chamber may function as the breather passage. In an illustrative embodiment, the one-way valve includes a base plate having a valve hole formed therein, and a flexible reed valve plate with one end affixed to the base plate.

Abstract: In an internal combustion engine in which air-intake valves reciprocate in parallel to the direction of reciprocal motion of pistons, an air-intake structure of an internal combustion engine includes an outward projection of the air-intake port that is reduced to achieve a downsizing of a cylinder head. An air-intake structure includes air-intake valves that are supported by a cylinder head having integrally formed air-intake ports so as to reciprocate in parallel with the direction of reciprocal motion of the pistons. Fuel injection devices are formed integrally with a throttle body on intake manifolds to be connected to the air-intake ports. The air-intake ports extend toward the cylinder head cover along a recess formed on the outer surface of the cylinder head that is connected to the intake manifolds at positions just before reaching the identical plane to a mating surface between the cylinder head and the cylinder head cover.

Abstract: A decompression apparatus includes a plunger and a decompression shaft. The plunger is provided in a plunger hole formed in a cam shaft which is configured to move an engine valve of an internal combustion engine. The plunger is movable in the plunger hole between a decompression position in which the plunger opens the engine valve and a decompression cancel position in which the plunger does not open the engine valve. The plunger hole has a first opening which partially locates on a cam surface of a valve cam which is provided on the cam shaft. A first end portion of the plunger protrudes from the first opening to open the engine valve in the decompression position. The decompression shaft is provided in the cam shaft and configured to move the plunger between the decompression position and the decompression cancel position.

Abstract: An oil filter mounting structure in an internal combustion engine in which the outside a crankcase in the direction of a crankshaft is covered by a case cover. A spacer is interposed between the crankcase and the case cover. The spacer is formed with a lubrication system. An oil filter is mounted to an oil filter mounting surface of the spacer which is flush with a mating surface with respect to the crankcase. A part of the crankcase to which the oil filter mounting surface of the spacer faces is formed with a recess opening on top to which the oil filter is mounted. The resulting configuration provides an oil filter mounting structure in which an oil filter is reliably protected from stones. Further, oil channels are shortened to achieve a compact light-weight internal combustion engine.

Abstract: In an internal combustion engine in which air-intake valves reciprocate in parallel to the direction of reciprocal motion of pistons, an air-intake structure of an internal combustion engine includes an outward projection of the air-intake port that is reduced to achieve a downsizing of a cylinder head. An air-intake structure includes air-intake valves that are supported by a cylinder head having integrally formed air-intake ports so as to reciprocate in parallel with the direction of reciprocal motion of the pistons. Fuel injection devices are formed integrally with a throttle body on intake manifolds to be connected to the air-intake ports. The air-intake ports extend toward the cylinder head cover along a recess formed on the outer surface of the cylinder head that is connected to the intake manifolds at positions just before reaching the identical plane to a mating surface between the cylinder head and the cylinder head cover.

Abstract: An oil filter mounting structure in an internal combustion engine in which the outside a crankcase in the direction of a crankshaft is covered by a case cover. A spacer is interposed between the crankcase and the case cover. The spacer is formed with a lubrication system. An oil filter is mounted to an oil filter mounting surface of the spacer which is flush with a mating surface with respect to the crankcase. A part of the crankcase to which the oil filter mounting surface of the spacer faces is formed with a recess opening on top to which the oil filter is mounted. The resulting configuration provides an oil filter mounting structure in which an oil filter is reliably protected from stones. Further, oil channels are shortened to achieve a compact light-weight internal combustion engine.

Abstract: A decompression apparatus includes a plunger and a decompression shaft. The plunger is provided in a plunger hole formed in a cam shaft which is configured to move an engine valve of an internal combustion engine. The plunger is movable in the plunger hole between a decompression position in which the plunger opens the engine valve and a decompression cancel position in which the plunger does not open the engine valve. The plunger hole has a first opening which partially locates on a cam surface of a valve cam which is provided on the cam shaft. A first end portion of the plunger protrudes from the first opening to open the engine valve in the decompression position. The decompression shaft is provided in the cam shaft and configured to move the plunger between the decompression position and the decompression cancel position.

Abstract: To provide a crankcase emission control system that enables the miniaturization of an internal combustion engine and the reduction in the manufacturing cost. In a crankcase emission control system of an internal combustion engine, a collecting part for collecting blowby gas conveyed in a breather tube on the case side and a breather tube on the cylinder head side and directing the blowby gas to a breather tube on the air cleaner side is provided over a connection, a connecting pipe on the case side, of the breather tube on the case side and a breather on the case side, below a connection, a connecting pipe on the cylinder head side, of the breather tube on the cylinder head side and a breather on the cylinder head side and below a connection of the breather tube on the air cleaner side and an air cleaner.

Abstract: An internal combustion engine including a torque converter on a crankshaft, and a single oil passage provided in the crankshaft for supplying, in common, both a working oil for the torque converter and a lubricating oil for the engine. A pump impeller of the torque converter is fixed to the crankshaft, and a clutch for connection and disconnection of engine output is provided on the side of a transmission.

Abstract: A structure has individual oil passages for different applications of oil. A torque converter is provided on a crankshaft having an axially extending center hole. A crank chamber and a transmission chamber are separated from each other through a one-way valve. A pipe is inserted in the center hole of the crankshaft to form an oil passage for supplying hydraulic oil for driving the torque converter, an oil passage returned from the torque converter, and an oil passage for supplying a lubricating oil to the area surrounding the crankshaft. The oil passage returned from the torque converter is in communication with a chamber defined by a pair of inner and outer oil seals for sealing a bearing mounted on the crankshaft, a lower portion of the transmission chamber, and an oil passage having a check valve at the downstream end thereof.

Abstract: To provide a crankcase emission control system that enables the miniaturization of an internal combustion engine and the reduction in the manufacturing cost. In a crankcase emission control system of an internal combustion engine, a collecting part for collecting blowby gas conveyed in a breather tube on the case side and a breather tube on the cylinder head side and directing the blowby gas to a breather tube on the air cleaner side is provided over a connection, a connecting pipe on the case side, of the breather tube on the case side and a breather on the case side, below a connection, a connecting pipe on the cylinder head side, of the breather tube on the cylinder head side and a breather on the cylinder head side and below a connection of the breather tube on the air cleaner side and an air cleaner.

Abstract: In an oil passage structure in a rotary shaft, including two systems of oil passages different in pressure that are provided extending from both ends of the shaft, the rotary shaft is provided with oil supply holes in the radial direction of the shaft for connection between a center hole in the shaft and locations to be supplied with oil. The oil supply holes are bored from the outside of the shaft. At this time, burrs are generated at end portions of the oil supply holes on the side fronting on the center hole. Where the depth of the shaft center hole is a dead end, removal of the burrs is not easy. The shaft center hole is used as an oil passage wherein burrs, if any, in the hole can be easily removed. The two oil passages are in communication with each other through a communication passage smaller than the oil passages in diameter. The smaller-diameter communication passage is closed by pressing a steel ball therein, thereby making both of the oil passages independent from each other.

Abstract: An overhead-valve internal combustion engine with a breather chamber arranged below a camshaft housing chamber for housing the camshaft and formed between a cylinder head and a cylinder block. A driving force transmission chamber is formed between a cylinder and a crankcase. Thus, the discharge of oil from the breather chamber is performed smoothly so as to enhance the vapor-liquid separation performance. A breather inlet passage has an upper end thereof in communication with an inside of a camshaft housing chamber and a lower end thereof in communication with a breather chamber at a position corresponding to a mating face between a cylinder block and a crankcase is formed in the cylinder block such that the breather inlet passage extends vertically. An oil discharge hole is in communication with a lower portion of the inside of the breather chamber and is formed in the crankcase.

Abstract: An overhead-valve internal combustion engine with a breather chamber arranged below a camshaft housing chamber for housing the camshaft and formed between a cylinder head and a cylinder block. A driving force transmission chamber is formed between a cylinder and a crankcase. Thus, the discharge of oil from the breather chamber is performed smoothly so as to enhance the vapor-liquid separation performance. A breather inlet passage has an upper end thereof in communication with an inside of a camshaft housing chamber and a lower end thereof in communication with a breather chamber at a position corresponding to a mating face between a cylinder block and a crankcase is formed in the cylinder block such that the breather inlet passage extends vertically. An oil discharge hole is in communication with a lower portion of the inside of the breather chamber and is formed in the crankcase.

Abstract: To provide a lubricating oil supply structure for an internal combustion engine, which requires no lubricating oil passage to be defined in a crankshaft, is capable of ejecting lubricating oil to a lubrication object, is free of limitations on the layout of the generator and peripheral devices, is capable of cooling generating coils of the generator, and allows the area of the lubrication object to which the lubricating oil is applied to be set with large freedom. A lubricating oil supply structure for an internal combustion engine has a generator having a stator with generating coils and a rotor. A one-way clutch is disposed opposite to the stator across the rotor. The lubricating oil supply structure includes a first nozzle disposed on a stator support of a generator cover for continuously ejecting lubricating oil. The lubricating oil is ejected from the first nozzle to the one-way clutch through holes which are disposed in a position confronting the one-way clutch in an ejected direction.

Abstract: A structure has individual oil passages for different applications of oil. A torque converter is provided on a crankshaft having an axially extending center hole. A crank chamber and a transmission chamber are separated from each other through a one-way valve. A pipe is inserted in the center hole of the crankshaft to form an oil passage for supplying hydraulic oil for driving the torque converter, an oil passage returned from the torque converter, and an oil passage for supplying a lubricating oil to the area surrounding the crankshaft. The oil passage returned from the torque converter is in communication with a chamber defined by a pair of inner and outer oil seals for sealing a bearing mounted on the crankshaft, a lower portion of the transmission chamber, and an oil passage having a check valve at the downstream end thereof.

Abstract: An oil passage extending from an oil pump to a discharge port in an internal combustion engine is, at its halfway point, branched into at least two oil passages, for example, a first oil passage and a second oil passage. One of the at least two branched oil passages, for example, the second oil passage is provided with a restricting portion configured as a first orifice for restricting a flow amount of oil by reducing a diameter of the first orifice. A bypass valve is provided which acts, when a hydraulic pressure in the second oil passage exceeds a specific value, to bypass the first orifice so as to increase the flow rate of oil. It is possible to increase the hydraulic pressure at the time of low speed rotation up to a necessary pressure only by providing the restricting portion, without enhancing the performance of the oil pump.

Abstract: An internal combustion engine including a torque converter on a crankshaft, and a single oil passage provided in the crankshaft for supplying, in common, both a working oil for the torque converter and a lubricating oil for the engine. A pump impeller of the torque converter is fixed to the crankshaft, and a clutch for connection and disconnection of engine output is provided on the side of a transmission.

Abstract: In an oil passage structure in a rotary shaft, including two systems of oil passages different in pressure that are provided extending from both ends of the shaft, the rotary shaft is provided with oil supply holes in the radial direction of the shaft for connection between a center hole in the shaft and locations to be supplied with oil. The oil supply holes are bored from the outside of the shaft. At this time, burrs are generated at end portions of the oil supply holes on the side fronting on the center hole. Where the depth of the shaft center hole is a dead end, removal of the burrs is not easy. The shaft center hole is used as an oil passage wherein burrs, if any, in the hole can be easily removed. The two oil passages are in communication with each other through a communication passage smaller than the oil passages in diameter. The smaller-diameter communication passage is closed by pressing a steel ball therein, thereby making both of the oil passages independent from each other.