SBIR-STTR Award

Diesel engines are widely used in military and commercial vehicles, as well as some light duty vehicles. The compression ratio is a compromise between power, economy, and cold startability. The optimum ratio for economy is below 15:1, whereas the necessary compression ratio for cold starting ranges from 16 to 22:1 depending on the specific engine design. This is too high for best economy and optimum boost. The proposal objective is to demonstrate a combination of simple mechanisms designed for the Caterpillar C-12 to improve fuel economy particularly during idle as well as improve engine power output. The technology will include varying the compression ratio between high (for cold starting) and low (for warmed-up running). Minimal or no engine block modifications are anticipated. The work proposed is to demonstrate hardware viability in a bench test rig as well as estimate/model fuel economy and power improvement from the proposed technology. For the SBIR OPTION, a system will be installed on one cylinder of a multi-cylinder engine and motoring tests run to demonstrate effectiveness.

Benefit:
Anticipated benefits are an improvement in fuel economy of more than 15%, increase in engine power by more than 5%, and a significant reduction in engine out emissions.

Keywords:
ratio, ratio, Compression, efficiency, Power, Engine, VALVE, Variable, Actuation

Large, open chamber Diesel engines are designed with compression ratios of 16 to 18:1 to facilitate cold starting. This is too high for best economy which is 14 to 15:1. Furthermore, these engines are designed for high power for highway vehicles with reserve for hill climbing and maneuvering. The objective is to demonstrate a combination of simple mechanisms designed for the Caterpillar C-12 to improve fuel economy particularly during light load operation as well as to allow improved engine power. One device will allow the compression ratio to vary between high (cold starting) and low (warmed-up running). A second device will disable some cylinders to improve idle and light load fuel economy which is particularly important for military surveillance, but useful for stationary generators and other applications where significant lighter load operation occurs. Minimal or no engine block modifications are anticipated. The work proposed demonstrates hardware viability in a firing engine. For the SBIR Phase II, the technology will be installed on all cylinders of the C-12 engine to demonstrate both compression ratio and disabling effectiveness. Computer modeling will guide the technology design and testing. A relationship with an established company(s) will be formed for manufacturing the technology.

Benefit:
Anticipated benefits of the fully developed technology are light load fuel economy improvements of between 15% and 33%, engine power increases more than 5%, and a significant reduction in engine out emissions. These benefits depend on the strategy chosen in consideration of cost, complexity, risk and timing.

Keywords:
VALVE, efficiency, ratio, Power, Variable, Compression, Engine, Actuation