| 摘要 |
A timing chain (5) is looped over a driving sprocket (2) attached to a crankshaft (1) and driven sprockets (4) attached to camshafts (3). A pivotable chain guide (A 1 ) having a plurality of rotatable rollers (41) for guiding movements of the timing chain (5) is provided on one side of the slack side of the timing chain (5). Adjustment force of a chain tensioner is applied to a remote end of the chain guide remote from the center of pivoting movement of the chain guide, thereby pressing the rollers (41) against the timing chain (5). The ratio (D 1 /D 2 ) between the pitch circle diameter D 1 of the driving sprocket (2) and the outer diameter D 2 of the rollers (41) is determined within the range of 5/3 to 5/1. This prevents insufficient lubrication of the chain guiding rollers (41), makes it easy to lay out the engine. |
