Coolant Pipe Press Fit Study 2011-01-0421

Coolant pipes are a prime connection units present in any engines that facilitates the flow of coolant and thereby keeping the engine under its optimum operating condition. Among the several influencing factors that deteriorate engines performance, the coolant leak is also one of the contributors. This could be caused primly due to leakage issues that arises from the pipe press fit zones. Henceforth it is very important to understand the root cause of this press-fit connection failure. The present study deals with press-fit between the pipe and housing in an engine which is subjected to extreme thermal loads (min of -40°C to a max temperature of +150°C) thereby causing the press-fit loosening effect. The main objective of this study is to perform a DOE using non-linear Finite Element analysis with seven input parameters (pipe insertion length, pipe wall thickness, pipe outer diameter, housing wall thickness, interference between the pipe and housing, coefficient of friction of the interaction and the hardness of the stainless steel pipe material). A converged response surface of the metrics output parameters (contact force, contact area and insertion force) are obtained to predict the quality of the press fit design and help to identify potential coolant leakage. The study shows that pipe insertion length is the most significant factor for both the output parameters contact force and insertion force and pipe outside diameter for the output parameter contact area. The results obtained from this study will help the designer to come up with the correct design parameters without performing any complex analysis, which reduces the design cycle time significantly.