Simulation of Contact Loss in a Heavy Duty Diesel Engine Valvetrain; Classical Approaches vs. Multibody Dynamic Model

The design of a cam profile and its effect on the dynamic performance of the operated mechanisms has long been a centre of attention. The main issue which restricts the cam design is maximum negative acceleration which can lead to contact loss. On the other hand the heavier parts in heavy duty diesel engine and existing pushrod in their valvetrain system aggravate this problem. The valvetrain mechanism is modeled by a multi-body system, using ADAMS, including discontinuities because of the loss of contact between two consecutive components of the valvetrain. Two classical contact separation criterion approaches is presented and they were investigated by MDB model. The correction in the approach lead to achieving the final generated cam lift which ensures permanent contact without change in spring properties and at the same time preserved engine performance.

کلیدواژه ها:

valve train dynamics ، multi-body dynamics ، contact separation criterion