The Effect of the Back-Pressure Changes in an Exhaust System on Vibration When Attaching a Variable Device during Idling.

The vibration of the ignition frequency component of the engine during idling causes driver discomfort. To minimize this, an optimal exhaust system with a variable device that can exert optimal pressure is required. In this study, the geometry of the variable device was designed in orifice and cylinder types. Next, the designed variable devices were implemented in a conventional exhaust system with an X chamber. A comparative analysis was conducted to propose an optimal geometry through back-pressure and vibration measurements. During the experiment, the orifice geometry exhibited higher back pressure than the conventional geometry and a large difference in back pressure before and at the exhaust gas merging position. Furthermore, the orifice geometry showed a 2.56% increase in the vibration of the 1X component in the Y-axis direction. By contrast, the cylinder geometry exhibited slightly higher back pressure than the conventional geometry and the smallest difference in back pressure before and at the exhaust gas merging position. The cylinder geometry showed a 2.45% reduction in the vibration of the 1X component in the Y-axis direction.