EGR Cooler Warranty Return Prediction Based on Product and Application Variation 2019-01-0915
The automotive industry drives some of the most stringent product requirements to ensure long product life and customer satisfaction. To demonstrate compliance with these requirements new and more accurate product evaluation methods are needed. Thermal fatigue life in EGR coolers for heavy duty diesel applications has historically been a critical focus for engine manufactures. Being able to accurately predict product return rates due to thermal fatigue gives the customer confidence that all end users will be satisfied, and allows program management to properly make fiscal decisions. This is accomplished by accounting for product variation and application variation in the product’s life calculation. Including these variations requires a simplified numerical method to calculate product life, as tens of thousands of samples will be run through the analysis to create statistically significant data. First, time dependent component temperatures are calculated based on engine conditions. The component temperatures are used to determine strain, which is then used to predict life. Appling this life calculation method to individual customer duty cycles or all duty cycles allows warranty return schedules to be predicted in various ways. This method has been proven to predict correct warranty return trends by studying a legacy EGR cooler, which has sufficiency field experience. It was also found that specific application life can be different than the life of the entire fleet. This is a critical distinction as fleet life determines financial liability for the product, while application life is key to customer satisfaction. With a greater understanding of engine duty cycles, the physics of thermal fatigue, and a new predictive tool it is possible to more accurately predict EGR cooler life, which provides critical data for program management.
William M. Rixon, Ryan Collins, Brian Costello, Billy Holland