A Purge Solenoid Structure-borne Noise Model 2001-01-1423
Evaporative emission control system purge solenoid valves in passenger cars and light-duty trucks are a noise source that engenders customer complaint. Valveonly noise tests produce results that are inconsistent with measured system noise. Such tests fail to account for variables introduced in situ. This study investigates valve-induced structure-borne noise as the major source of system noise. It researches a theoretical method to relate structure-borne purge solenoid system noise requirements, valve-only, and vehicle mounting system dynamic requirements. It aims to validate the researched method and determine the nature of a valve-only bench test and a mounting system dynamic test. Several systems' noise levels, inertance, and acoustic responses were measured. The bench test vibration for each solenoid valve was also measured. This study discovered that the internal force of the purge solenoid may change with the mounting system compliance. To produce an accurate bench test, it might be necessary to account for this fluctuation. The data collected by provisional tests validated the proposed methods. These tests, while more accurate than any previous tests, still require modification in order to predict with an accuracy demanded by today's competitive market.