Continuously Variable Displacement Drive for Engines Part 1, Performance Simulation

A new type of drive system has been designed, analyzed, patented, prototyped, and tested. The drive’s unique capabilities include the ability to vary the bottom dead center position to reduce the stroke, and simultaneously vary the top dead center position to achieve the desired compression ratio with one simple, low friction mechanism. The purpose of the concept is to reduce losses associated with operation at partial load as most engines spend a preponderance of their operating life at partial load. Cummins sponsored engine simulation of the CVD configured as a 9-cylinder gasoline engine cycle and a baseline engine which was a conventional V8 engine of the same displacement and compression ratio. The study showed a ~30% improvement in fuel economy on a 10-mode weighted cycle that was designed by Cummins to simulate the FTP cycle. This paper covers the performance analysis while SAE 2021-01-0451, “Continuously Variable Displacement Drive for Engines, Part 2, Design, Analysis, and Test” covers the remaining work.