The HVA system utilizes proprietary ultrafast digital latching valves which allows for precise control of the gas exchange process. The Miller cycle will be employed to vary the effective compression ratio over the operating range. This approach allows us to take advantage of a high expansion ratio while avoiding knock. The flexibility will also allow us to achieve precise air fuel ratios without the typical throttling losses associated with spark ignited natural gas engines. Engine efficiency is expected to increase by 10-15% especially at light to medium loads. In addition, as part of this project, Sturman will use HVA to investigate the benefits of high turbulence and internal EGR through independent intake valve phasing and exhaust valve timing control, respectively.

—Dan Giordano, Principal Investigator on the project

Performing the engine management will be Sturman’s Condor HVA controller and the Sturman Total Engine Controller (STEC) which closes the loop on combustion to continuously adapt to varying fuel quality.

Although generator sets typically only run at a few discrete points, raising the questioning of the need for flexibility, the situation highlights the greatest benefit of Sturman’s HVA and closed-loop engine controls, the company says. The ability to adapt to varying fuel quality and continuously optimize the combustion process for maximum efficiency means that a single engine architecture can be used for power generation, as well as on-highway and off-road mobile applications.

The core Sturman controls utilized in this demonstration program are part of the Sturman Digital Hydraulics technology platform.

Sturman Industries is an industry leader in HVA technology, referred to as camless systems. HVA eliminates the mechanical linkage between the engine valves and the crankshaft, allowing for fully flexible engine valve operation and enabling improved engine power, efficiency, and emissions.

Since 1996, Sturman has produced systems ranging from basic open loop single-lift systems to advanced closed-loop systems with variable timing, lift, and multiple event operation. Sturman HVA technology has been installed in more than 60 applications ranging from 250cc single cylinder motorcycle engines to 13L heavy-duty diesel engines for research and demonstration programs.