Chapter 3 Ventilation system Section 1 Valve train 3.1.1 Intake valve timing phase (1)intake advance angle a: Near the end of the exhaust stroke,when the crankshaft rotates to an angle away from upper dead point,the intake valve opens. (2)intake lag angle B: Through the intake stroke,after passing the lower dead point,the piston then ascends for a while,the intake valve closes. intake process duration t:180+a+B Early intake valve opening,when the intake stroke begins,the valve has opened larger,air flow can smoothly fill into the cylinder. When the piston reaches lower dead point,the cylinder gas p is still lower than po,and exists still vacuum.Under the inertia of air flow and vacuum suction,gas still also fills into the cylinder.Late intake valve closing is conductive to aeration. 机被电子工程学膜 Automobile and Tractor Northwest A&F UniversityAutomobile and Tractor Northwest A&F University Chapter 3 Ventilation system 3.1.1 Intake valve timing phase (1) intake advance angle α： Near the end of the exhaust stroke, when the crankshaft rotates to an angle away from upper dead point, the intake valve opens. (2) intake lag angle β： Through the intake stroke， after passing the lower dead point，the piston then ascendsfor a while, the intake valve closes. intake process duration t：180+α+ β Early intake valve opening, when the intake stroke begins, the valve has opened larger, air flow can smoothly fill into the cylinder. When the piston reaches lower dead point, the cylinder gas p is still lower than po, and exists still vacuum. Under the inertia of air flow and vacuum suction, gas still also fills into the cylinder. Late intake valve closing is conductive to aeration . Section 1 Valve train