GEAR ASSEMBLY, GEAR TRAIN ASSEMBLY AND ITS ASSEMBLING METHOD

摘要

PROBLEM TO BE SOLVED: To effectively reduce backrush by providing a backrush preventing gear assembly in a part of a timing gear train in order to change the fuel injection timing, and constituting this assembly by relatively rotatably superpos ing two gears differed in tooth width by a specified quantity. SOLUTION: This backrush preventing gear assembly 58 formed by relatively rotatably superposing two gears differed in tooth width by about 50% is meshed with a drive gear 42 on a crank shaft 24 in the timing gear train 40 of an internal combustion engine 20, and an idle gear 100 supported by a block 22 is meshed with this gear in such a manner as to be positionally adjustable by a positioning mechanism 120. The idle gear 100 is meshed with a backrush preventing gear assembly 200 having gears similarly formed by relatively rotatably superposing two gears to rotate a fuel injection camshaft 32, and the fuel injection timing is regulated. Further, a valve camshaft 34 is rotated through a gear 300 to regulate the opening and closing timing of a valve.