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Camshaft Design System
| Any automotive system that moves – engine, driveline, or chassis – can benefit from FunctionSim's analysis of loads, reaction forces and displacements. Racing teams are finding that our unique capabilities are ideally suited to optimizing the performance of vehicles designed to travel above highway speeds and engines with red lines above 10,000 RPMs. In particular, valvetrain analysis is an area of growing interest in the motorsports community. Design goals include maximizing valve lift, minimizing loft and bounce, and choosing the best combination of valvetrain component masses and springs. This article (2MB PDF) in the July 2007 Performance Racing Industries Magazine describes the role of RecurDyn in computer-aided design, manufacturing, and engineering (CAD/CAM/CAE) for motorports. |
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A number of Toolkits and interfaces have been developed to provide detailed models of valvetrain components:
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Camshaft Design System
CDS is a modern, powerful software developed to calculate cam profiles for the simulation of engine valve trains and for actual grinds. The use of state-of-the-art computer algorithms allows the user to design valve lift curves, without being confronted with the underlying math. A basic knowledge of valve train design is sufficient, but necessary, to successfully design a valve train system. To the right, you will see a cam superimposed with its Herzian stress distribution and oil film thinkness through a range of 600-7000 RPMs.
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Multi-Mass Springs
The difference between desired valve lift and actual valve lift at high RPMs is governed in large part by the behavior of the valve spring. In particular, the natural frequency of the spring – at the maximum lift compression – will determine whether positive contact between the cam and lifter is maintained, or whether valve loft occurs. RecurDyn provides a number of multi-mass spring models to handle round, elliptical and ovate wire profiles, cylindrical, cone and beehive springs in single or dual-rate configurations.
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MFBD Springs
Progressive springs are typically used for modern high speed combustion engines, which can often break directly over the sharp edge of the flattened end of the last coil. In this case the explanation is fairly easy: failure due to high contact pressure in this area. But in many cases the spring breaks between 180° - 270° after this point, at a location where a breakage is least expected. To fully understand the reason for these failures, true dynamic stresses have to be calculated by considering the correct geometrical shape of the spring, contact forces due to coil clash and the dynamic behavior of the highly flexible spring. The M
FBD technology of RecurDyn allows the correct representation of these flexible and complex contacts under full consideration of the spring dynamics. On the right, you can see a close up of a beehive spring's tensile stress at maximum lift.
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