Abstract
A GDI* (Gasoline Direct Injection) engine exhibits the high fuel efficiency associated with a diesel engine under light loading and the high output associated with a pre-mixed gasoline engine under heavy loading. To achieve stable combustion in a gasoline direct injection engine, it is necessary to concentrate the air/fuel mixture around the spark plug for stable flame propagation. Unfortunately, since the permissible range of mixture concentrations is narrow, it has been considered difficult to achieve stable combustion over a wide range of operating conditions. Mitsubishi Motors invented a concept known as "wide spacing" to overcome this limitation. By providing a high degree of freedom in the control of mixture preparation, the wide spacing concept has allowed the adoption of new combustion control technologies such as two-stage mixing for knock prevention and two-stage combustion for quicker catalyst light-off. Thus, the wide spacing concept has greatly expanded the potential of a gasoline direct injection engine.