Boretti, A., "Compressed Natural Gas and Hydrogen Fuelling of a Naturally Aspirated Four Stroke Engine with One Intake and One Exhaust Horizontal Rotary Valve per Cylinder and Central Direct Injection and Spark or Jet Ignition," SAE Technical Paper 2015-01-0325, 2015, doi:10.4271/2015-01-0325.
The paper discusses the benefits of a four stroke engine having one intake and one exhaust rotary valve. The rotary valve has a speed of rotation half the crankshaft and defines an open passage that may permit up to extremely sharp opening or closing and very large gas exchange areas. This design also permits central direct injection and ignition by spark or jets. The dual rotary valve design is applied to a naturally aspirated V-four engine of 1000cc displacement, gasoline, methane or hydrogen fuelled with central direct injection and spark ignition. The engine is modeled by using a 1D engine & gas dynamics simulation software package to assess the potentials of the solution. The novelty in the proposed dual rotary valve system is the combustion chamber of good shape and high compression ratio with central direct injector and spark plug or jet ignition, coupled to the large gas exchange areas of the rotary system. The proposed design works for gasoline and alternative liquid or gaseous fuels. Introduction of load control by quantity of fuel injected is possible by replacing the spark plug ignition with a jet ignition device that delivers a much faster and effective bulk ignition. This latter option is not covered in the present study.