V-band joint was originally developed during World War II by the Marmon Corporation for use in the aircraft industry. The U.S. Military used Marman clamp to secure the atomic bombs during transport at the end of the Second World War. It has been widely used in a variety of applications including pumps, engines, exhaust systems, turbochargers to offer effective fastening solutions and greatly simplify assembly and service. In addition, the orientation of the connected components can be easily adjusted according to customer's request. So it has been popularly adopted in the field of turbochargers.
The axial clamping force and anti-rotating torque are two key parameters in turbocharger applications to verify the quality of the v-band joint during its operation. It is important for the v-band joint to have sufficient axial clamping force to prevent leakage and wheel damage. Meanwhile, it is necessary to have enough anti-rotating torque to prevent separation of the housings and relative rotation between housings and v-band joint. When the relative rotation happens, actuation setting may change leading to turbocharger overspeed.
This paper presents a methodology to predict axial clamping force and anti-rotating torque for turbocharger used in commercial vehicle at room temperature. This methodology can guide designers in the initial design stage for the v-band joint. It can also offer product engineers a fast solution to calculate the clamping level of the v-band joint.
In order to validate the methodology, finite element analysis (FEA) including v-band joint and end housings is performed. Because of contact phenomena between v-band and housings, the FEA simulation is highly non-linear and very time consuming. It is therefore impractical to use FEA to routinely design v-band joints. Nevertheless, FEA method does give a greater insight into the behaviors of v-band joint. In this paper, FEA is perceived as an effective validation methodology.
Testing hardware is usually considered as the most realistic and accurate validation. The anti-rotating torques of the v-band joints in 4 different platforms predicted by the current methodology is validated using the torques measurement from the tests. Test setup and procedure are also briefly introduced in this article.
Comparison among the results of theoretical models, FEA and experimental work definitely conclude that the analytical methodology for v-band joint is accurate within acceptable errors. As compared to FEA and testing, the current method is very efficient in predicting axial clamping force and anti-rotating torque. It is time-saving compared to FEA simulation and cost-saving with respect to the test. This methodology provides a knowledge base for the design and operation of v-band joint, and can be used for a wide rang of v-band joint especially for commercial vehicle applications.
Key words: Commercial vehicle, Power train system, Turbocharger, V-band joint, Axial clamping force, Anti-rotating torque, T-bolt