曲轴转两周，发动机里的气缸完成一个作功行程。
By the time the crankshaft completes two revolutions, each cylinder in the engine will have gone through one power stroke.
在作功行程，进气门和排气门关闭，火花塞点燃混合气，活塞向下移动。
On the power stroke, the intake valve and exhaust valve close. The spark plug ignites the air-fuel mixture, the piston moves down.
作功行程：活塞处于汽缸中的上止点，火花塞点燃充分压缩后的混合气体。
Power stroke: As the fuel is compressed and the piston nears the top of the cylinder the spark plug fires and ignites the fuel and air.
通过理论分析和对比，提出采用主辅线圈串联励磁的方法来改善励磁线圈的作用效果，使动铁心在较长的运动行程下始终能获得足够的操作功。
As results, a novel excitation method with main coil and auxiliary coil in series is presented so as to make the armature obtain enough energy to move all through.
通过理论分析和对比，提出采用主辅线圈串联励磁的方法来改善励磁线圈的作用效果，使动铁心在较长的运动行程下始终能获得足够的操作功。
As results, a novel excitation method with main coil and auxiliary coil in series is presented so as to make the armature obtain enough energy to move all through.
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