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This paper provides an overview of the analysis and design of the DigitalAir™ camless valve train including the architecture and design of the valve and head; the details of the electric valve actuator, and the flow characteristics of the valves and resulting charge motion in a motoring engine. This valve train is a completely new approach to fully variable valve actuation (FVVA), which allows almost unlimited continuously variable control of intake and exhaust valve timing and duration without the use of a camshaft. This valve train replaces conventional poppet valves with horizontally actuated valves located above the combustion deck. As the valves move, they open and close a number of slots connecting the cylinder with the intake and exhaust ports. The valve stroke necessary to provide the full flow area is approximately 25% of the stroke of the equivalent poppet valve, thus allowing direct electrical actuation with very low power consumption.

Home refueling systems for natural gas vehicles are commercially available but suffer from long refilling times and high system costs. A novel concept of selectively repurposing one cylinder of a compressed natural gas (CNG) engine to be used as a compressor would allow a CNG vehicle to refuel itself quickly and with low capital cost. Using funding from the DOE through the ARPA-E program, such a vehicle is being designed and built by Oregon State University with the help of Czero, Inc. This paper outlines some of the early design, analysis and simulation work done to prove the concept and arrive at a first prototype design. Some of the unique challenges associated with the concept are discussed and the solutions to them are presented. An accompanying paper will present test results for the system.