The development of electronic multipoint fuel-injection technology by Masahiko Miyaki, Yukihiro Shinohara, and Katsuhiko Takeuchi has revitalized the popularity of diesel engines by enabling high-power operation with better fuel efficiency and lower emissions than conventional injector technology. The trio’s concept of common rail direct fuel injection featured an electronically controlled multi-fuel injection system (ECMFIS) to overcome the limitations of common rail system prototypes of the 1960s. Incorporating an electronically controlled injector and sensors for speed, cylinder identification, and pressure, they were the first to successfully commercialize the diesel common rail system, which was put into production in 1995. Prior to their work, the popularity of conventional diesel engines was waning, almost to the point of extinction, due to significant black smoke emissions from poor atomization of fuel caused by low injection pressure. Miyaki, Shinohara, and Takeuchi’s system allowed high fuel injection pressure, even at low engine speeds, for finer atomization resulting in less unburned fuel and fewer particulates. Fuel efficiency is also achieved by the ability to store high-pressure fuel in the rails and electronically injecting it into the combustion chamber as needed. The first-generation ECMFIS reduced emissions of nitrogen oxides and particulates by half and cut combustion noise by as much as 10 dB, while increasing output and torque by 10% and 15%, respectively. Continuing to enhance the technology, the team’s fourth-generation common rail system (2013) provides up to nine divided fuel injections per cycle at extremely high pressure, cutting emissions by 80% and further reducing combustion noise compared to the early ECMFIS. They also developed an innovative feedback control system that can compensate for aging deterioration of the fuel injectors to ensure clean emissions and high drivability throughout the lifespan of the engine.
A Fellow of the Japan Society of Mechanical Engineers, Masahiko Miyaki is executive vice president at DENSO Corporation, Kariya-shi, Japan.