Reliability Assessment of the Casted Steel Function Block in Gasoline Fuel Rails

In this study, the reliability of the casted function block, a critical component of the fuel rail assembly (FRA), is examined under the pressure and thermal loads typically encountered in an engine compartment. The function block serves a dual purpose: it acts as a holder for the fuel rail, securing it to the cylinder head (CH), and it includes the injector cup, which connects the injectors to the rail. This component is manufactured as a single piece using casting methods. To assess the stress experienced by the function block, Finite Element Analysis (FEA) techniques are employed. Additionally, a specialized mechanical pulse test is developed to determine the fatigue limits of the casted function block. This testing is crucial for understanding how the component will perform under cyclic loading conditions. The failure probability of the function block is quantified by generating S-N (stress-cycle) curves based on the results from the mechanical pulse tests. These curves illustrate the relationship between the applied stress and the number of cycles to failure, allowing for a comprehensive analysis of the component's durability. Ultimately, the study demonstrates that the failure probability of the casted function block is estimated to be less than 1 ppm (parts per million) for serial production. This finding confirms that the function block meets the stringent reliability requirements necessary for automotive applications, ensuring its performance and safety in the demanding environment of an engine compartment.