Valve system for engine

A valve system for an engine, the engine including a cylinder block having a crankcase formed integrally therewith and a cylinder bore formed therein, a cylinder head connected to the cylinder block, a crankshaft rotatably supported by the crankcase, a piston slidably fitted in the cylinder bore and being operatively connected to the crankshaft, and a camshaft having an axial line parallel to an axial line of the crankshaft, the camshaft being interlocked with the crankshaft at a reduction ratio of 1/2 and being disposed on one side of the crankshaft rotatably supported by the crankcase, said valve system comprising:

• a rocker shaft fixedly supportable by the cylinder head;
• a rocker arm supported by said rocker shaft for rocking motion thereon in accordance with rotation of the camshaft, said rocker arm being operatively connected to engine valves of the engine;
• said rocker shaft is arranged to have an axial line thereof crossing an axial line of the crankshaft on a projection plane perpendicular to an axial line of the cylinder bore;
• and
• an input arm extending on said projection plane from said rocker arm to said one side of said crankshaft is provided on said rocker arm rockably supported by said rocker shaft.

An engine, comprising:

• a cylinder block having a crankcase formed integrally therewith and a cylinder bore formed therein;
• a cylinder head connected to said cylinder block;
• a crankshaft rotatably supported by said crankcase;
• a piston, said piston being slidably fitted in said cylinder bore and being operatively connected to said crankshaft;
• a camshaft having an axial line parallel to an axial line of said crankshaft, said camshaft being interlocked with said crankshaft at a reduction ratio of 1/2, said camshaft being disposed on one side of said crankshaft and being rotatably supported by said crankcase;
• a first rocker shaft fixedly supported by said cylinder head;
• a second rocker shaft fixedly supported by said cylinder head
• a first rocker arm supported by said first rocker shaft for rocking motion thereon in accordance with rotation of said camshaft, said rocker arm being operatively connected to a pair of first engine valves;
• a second rocker arm supported by said second rocker shaft for rocking motion thereon in accordance with rotation of said camshaft, said rocker arm being operatively connected to a pair of second engine valves, said second engine valves being different than said first engine valves;
• said first rocker shaft and said second rocker shaft are arranged to have axial lines thereof crossing an axial line of said crankshaft on a projection plane perpendicular to an axial line of said cylinder bore;
• a first input arm and a second input arm extending on said projection plane from said first rocker arm and said second rocker arm, respectively, to said one side of said crankshaft are provided on said first rocker arm and said second rocker arm, respectively;
• a first rod and a second rod reciprocating in axial directions in accordance with the rotation of said camshaft, said first rod and said second rod being connected to said first input arm and said second input arm, respectively, to rock said first rocker arm and said second rocker arm in valve opening directions, respectively.