F2008-04-016
A Study of Optimization of FEM Carrier Stiffness for Reducing Idle Vibration
Nowadays, most of car manufacturing companies and suppliers have been focusing all of their abilities on improving a NVH (Noise, Vibration and Harshness) performance in a car because customers wanted to buy cars which have good NVH qualities - silence, comfortable and so on. So, idle vibration, one of the very important NVH performances, affected the customer longing for buying a car as a sales point of view.
However, a lot of engineers could not easy to know reasons why the idle vibration occurs and had difficult to define a clear mechanism of the idle vibration path because a car is assembled by a complicated process and composed of about 25,000 ~ 30,000 components. So, we, NVH engineers, have opportunity to try a variety of approaches for meeting the required idle vibration solutions and know that FEM(Front End Module), one of the car modularization components consisting of about 9 sub-components, gives so useful things for controlling the idle vibration.
Therefore, So many automotive companies and suppliers have been adopted FEM into a car in order to reduce manufacturing process, weight and cost. Otherwise FEM is on the way to becoming an automotive standard. However, in terms of NVH Performance, FEM has been giving some difficult problems related to Idle Vibration which comes out from a rotational vibration of the cooling fan at idle rpm to engineers. This means that a level of idle vibration can be high if FEM has not enough for the stiffness in order to support cooling system. So, this paper presents a design guideline of FEM carrier which can be a isolator reducing transferring vibration from the cooling fan to the body and a dynamic damper reducing body vibration itself at idle engine rpm by securing the FEM carrier stiffness through the analytical and experimental methods.
Poster presentation: Body design for passenger cars, trucks and buses