| 摘要 |
A valve timing chain drive 10 in an internal combustion engine comprises a chain CH1 meshing with sprockets of the crankshaft S11 and the camshaft S13, S14, a movable guide G11 pressed against a slack side of the chain, a second pivoted guide G12 slidably engaged with the tension side of the chain, said second guide being operated by a cam C1, the rotation of the cam being synchronized with the rotation of the camshaft or the crankshaft such that the tension on the chain oscillates according to cyclic variations in the torque of the camshaft. The second shoe G12 moves fastest towards the chain when the chain experiences minimum tension, and moves quickest away from the chain when the chain experiences maximum tension. In this way the chain experiences a somewhat uniform tension. The cam may be oval, or rectangular, and may be mounted directly on the crankshaft or camshaft, or may be operated via a gear train. |
