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蓝魔 · Jul 20th, 2012, 16:34

http://www.e31.net/engines_e.html

The Inline-Four Engine

Now things get complicated. Although it seems that a four cylinder engine is free of vibration, it is not.
An inline four engine fires every 180° which means that always two pistons are in the same position and move in the same direction. Because of the symmetrical arrangement there is no end-to-end vibration as with the three cylinder engine (piston 1 and 4 plus 2 and 3 are pairs).
Thre problem is the vertival movement. At first glance it seems that the forces generated by the first piston are cancelled by the second and the forces of the third are cancelled by the fourth. But that is not the case!
As you can see in the picture, pistons which are moving up, are moving at different speeds than pistons that are moving down. So there are vibrations again which have to be cancelled by balancer shafts.

The crankshaft of an inline four engine.
Frontal view of crankshaft.

Forces generated by pistons and rods which are moving up and
down do not cancel themselves but result in 'second order forces'.

Jul 20th, 2012, 16:34	#1
蓝魔 Senior Gear 注册日期: Jan 2008 帖子: 10,896 积分:66 精华:18	不同种类引擎的平滑解释 http://www.e31.net/engines_e.html The Inline-Four Engine Now things get complicated. Although it seems that a four cylinder engine is free of vibration, it is not. An inline four engine fires every 180° which means that always two pistons are in the same position and move in the same direction. Because of the symmetrical arrangement there is no end-to-end vibration as with the three cylinder engine (piston 1 and 4 plus 2 and 3 are pairs). Thre problem is the vertival movement. At first glance it seems that the forces generated by the first piston are cancelled by the second and the forces of the third are cancelled by the fourth. But that is not the case! As you can see in the picture, pistons which are moving up, are moving at different speeds than pistons that are moving down. So there are vibrations again which have to be cancelled by balancer shafts. The crankshaft of an inline four engine. Frontal view of crankshaft. Forces generated by pistons and rods which are moving up and down do not cancel themselves but result in 'second order forces'.
蓝魔 Senior Gear 注册日期: Jan 2008 帖子: 10,896 积分:66 精华:18	Never argue with an idiot. He will consistently drag you down to his level and beat you with experience.