The patent category for engines receives 20 to 50 new applications annually. Robert Stirling patented his external combustion engine in 1816, which utilizes a temperature differential within a closed container and a regenerator to maintain heat.
Ford's EcoBoost engine line, under development since 2009, features a direct fuel injection system patented in 2014. This system uses sensors to optimize fuel mixtures and utilizes exhaust gas energy to drive a turbine and compressor.
RSC Energia has patented a helicon plasma electric engine for spacecraft. The design replaces the traditional heavy magnetic system with a coil made of ferromagnetic wire to reduce overall engine weight.
Nikola Tesla patented an induction alternating current motor in 1888. The device operates via a magnetic field generated by alternating current in a copper starter winding and is currently used in electric vehicles.
