Tempareture Compensation Of Vehicle Engine Parts Leak Test

Air tightness test, also known as leak test, is proceeded during vehiclecylinder block and cylinder head manufacturing. It is observed that the resultsof leak tests are affected by parts and environment temperature. Thustemperature compensation is necessary during the leak test. There are twocategories of current methods of leak test temperature compensation, one ofthose based on ideal gas law and another based on regression analysis ofhistory manufacturing data. These methods are limited with specific conditionsor applying costs, which makes them not applicable in some occasions.Characteristics of Aluminum cast alloys leakage are analyzed from theperspective of poromechanics. Variation of part leak rate on air temperature,viscosity and pressure of cavity is developed based on the analysis. Processesof leak test are divided into two procedures, the charging–stabilizingprocedure and the testing procedure. Cavity temperature and pressure arefound stabilized at the end of the first procedure. Analysis and numericalsimulations are applied on the second procedure, coming up with therelationship between temperature variation and temperature differencebetween inside and outside of tested part. A low-cost high-accuracytemperature measurement instrument is developed based on digital ICtemperature sensors to meet the requirements of experiments, and regulatealgorithm is designed against the delay characteristics of the sensor. Atemperature compensation method is developed based on these results. Themethod is proven to be more accurate than previous methods by analyzingexperiment results.