Compression ignition engine by air injection from air-only cylinder to adjacent air-fuel cylinder

The internal combustion engine relies on air injection for ignition instead of Otto cycle spark or Diesel cycle fuel injection. Cylinder pairs are connected by a cylinder-connecting valve, which opens near top-dead-center on the compression stroke injecting high-pressure air from one cylinder into a second cylinder containing an air-fuel mixture thereby inducing detonation ignition at top-dead-center. During the expansion stroke, the cylinder-connecting valve remains open and provides equal pressure on both cylinders, which is substantially higher than possible in an Otto cycle. Constant volume heat addition makes this engine more efficient than the Diesel cycle. Compared to conventional engines, the absence of spark ignition or high pressure fuel injectors makes this engine more economical, more reliable, and scalable down to small sizes where fuel metering limitations of Diesel fuel injectors become problematic. The engine can serve as a reactor for generating high temperature hydrogen to power high temperature fuel cells.