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A smart waste gate (WG) turbocharger controls boost by bypassing turbine flow through the WG port which allows optimizing both low and high speed engine performance. However, the WG port in the turbine housing involves much complex geometry which leads to potentially higher thermal stress and plastic strain if design is improper. This paper first presents the common thermal cracking problems at port zone and then shows finite element analysis (FEA) results for one design. The predicted location correlates well with the observed failure port location. A design study with key parameters for the port is conducted under same boundary conditions. Key parameters include height H, inner diameter D and inner diameter fillet r of the port. Totally 13 designs are analyzed under packaging and performance limitation. Accumulated plastic strain (APS) from FEA is used to evaluate different designs. Curves are plotted to show the relationship between APS and design parameters.

In this work we have proposed an interesting clamping solution of V-band which has an important industrial impact by reducing the cost and assembly process as well compare to the traditional V-band. The design what we are focusing for is applied for all size of turbochargers which helps to connect the hot components such as manifold and turbine housing. The cost for V-band is mainly from T-bolt. It is made from special stainless steel which represents 50% of the total cost. In this work it is proposed a new V-band joint by changing bolt clamping status from tension to compression. From tension to compression we change the bolt material from high cost steel to low cost steel. The new total cost is reduced by 40%. The prototype is made and performed in static tests including anti-rotating torque test and salt spray test. The new joint meets the design requirements at static condition. Further work will focus on the dynamic qualification and at high temperature as well.