Dual Fuel Injection for Catalytic Converter Heating

The fuel injection process is divided into two distinct phases: a first injection before top dead center that creates a lean air/fuel mix, and a second post-injection after top dead center that enriches the mixture. This segmentation allows each injection to serve a specific purpose - the first for stable combustion and the second for generating high exhaust temperatures to quickly heat the catalytic converter.

The first fuel injection is performed in advance (before top dead center) to establish a lean air/fuel mixture that ensures stable combustion. This preliminary action prepares the combustion chamber with a controllable base mixture, allowing the subsequent second injection to effectively enrich the mixture and generate the desired thermal effects without causing uncontrolled combustion.

The injection process is segmented into two phases with distinct functions. The first injection before top dead center ensures combustion stability by establishing a lean mixture that ignites reliably. The second injection after top dead center focuses on enriching the mixture to increase exhaust gas temperature, thereby separating the stability function from the temperature enhancement function.

The patent applies different air/fuel mixture qualities at different stages of the combustion process. The initial lean mixture provides stable combustion characteristics, while the subsequently injected fuel creates localized enriched regions that burn more completely and generate higher temperatures in the exhaust gases, thus optimizing both stability and temperature through spatial and temporal variation in mixture quality.

The lean air/fuel mixture is prepared in advance through the first injection before top dead center, ensuring good fuel utilization and reduced emissions during the main combustion phase. Subsequently, a second fuel injection enriches the mixture after ignition has begun, allowing the combustion to progress at higher temperatures to heat the catalytic converter, thus achieving both efficient fuel use and high temperature in sequence.

The fuel injection is applied periodically in two distinct pulses during the combustion cycle. The first pulse creates a lean mixture for efficient combustion, and the second pulse periodically enriches the mixture during the combustion stroke to boost temperature. This periodic injection strategy allows the system to alternate between fuel-efficient lean burn and temperature-enhancing rich burn phases within a single cycle.