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A 4-cycle internal combustion engine including a crankcase, a cylinder, a cylinder head, a piston adapted to reciprocate within the cylinder, a combustion chamber formed by the piston, the cylinder and the cylinder head, and a crankshaft connected to the piston via a connecting rod, is improved in o

A 4-cycle internal combustion engine including a crankcase, a cylinder, a cylinder head, a piston adapted to reciprocate within the cylinder, a combustion chamber formed by the piston, the cylinder and the cylinder head, and a crankshaft connected to the piston via a connecting rod, is improved in order to enhance its thermal efficiency, to reduce exhaust emissions and to make it possible to operate the engine while the engine is in any attitude. The improvements reside in an intake passage and an exhaust passage provided in the cylinder head, a rotary valve rotating synchronously with the crankshaft at a speed one-half of that of the latter for placing the intake passage and the exhaust passage in communication with the cylinder during an intake stroke and an exhaust stroke of the piston, respectively, a check valve through which the intake passage communicates with the interior of the crankcase so that only flow is allowed from the crankcase towards the intake passage, and a carburetor device for feeding a fuel mixture of air, fuel and lubricant oil into the crankcase. The suction of the fuel mixture into the crankcase chamber as well as the feeding of the fuel mixture within the crankcase to the intake passage are made possible by the variation in pressure within the crankcase chamber caused by the reciprocation of the piston.

대표청구항 ▼

A 4-cycle internal combustion engine comprising: a crankcase, a cylinder integral with the crankcase, a cylinder head defining intake and exhaust passages therein and capping said cylinder, said intake passage communicating with the interior of said crankcase, a piston slidably fitted in said cylind

A 4-cycle internal combustion engine comprising: a crankcase, a cylinder integral with the crankcase, a cylinder head defining intake and exhaust passages therein and capping said cylinder, said intake passage communicating with the interior of said crankcase, a piston slidably fitted in said cylinder so as to be reciprocatable therewithin, said piston, cylinder and cylinder head delimiting a combustion chamber, a crankshaft extending within said crankcase and rotatably supported in the engine, a connecting rod connecting said piston and said crankshaft so as to limit the reciprocation of said piston between top and bottom dead center positions thereof, said cylinder having an exhaust port extending through a side wall of the cylinder and open to the interior of the cylinder at a location above the piston when the piston is in the bottom dead center position thereof, a rotary valve disposed between said intake and said exhaust passages and the combustion chamber, said rotary valve being operable to selectively place said passages in communication with said combustion chamber by opening said intake passage to the combustion chamber and opening said exhaust passage to the combustion chamber during one complete revolution of the valve, a synchronizing drive mechanism synchronizing said rotary valve with said crankshaft so as to rotate at a ratio of 1:2 with respect to the rotation of said crankshaft, so as to be in a rotary position which places said intake passage in open communication with the combustion chamber during the intake stroke of the piston, and so as to be in a rotary position which places the exhaust passage in open communication with the combustion chamber during the exhaust stroke of the piston, a check valve operatively interposed between said intake passage and the interior of said crankcase in communication therewith, said check valve allowing flow only in a direction toward said intake passage, and fuel feed means for introducing a mixture of air, fuel and lubricating oil to the interior of said crankcase, the mixture being aspirated into the crankcase and being fed from the interior of the crankcase to the intake passage by variations in pressure in the crankcase caused by the reciprocation of said piston.