Ignition and knock tolerance in internal combustion engine by controlling EGR composition

摘要

A method for improving ignition of a spark ignited internal combustion engine by controlling the composition of recirculated exhaust gas. It is assumed that the engine has a spark ignition system and an exhaust gas recirculation (EGR) loop such that at least one of the combustion cylinders is an EGR cylinder that generates an EGR stream carried by the EGR loop. Thus, the combustion charge is a mixture of air, fuel and recirculated exhaust. A first step is receiving combustibility data representing the current ignitability of the charge. It is then determined whether the energy of the ignition system is sufficient to ignite the charge. If not, the amount of hydrogen in the EGR stream is increased, which increases the ignitability of the charge.

主权项

1. A method of matching the ignitability of the charge provided to combustion cylinders of an internal combustion engine to the current state of the engine's ignition system, the engine having an exhaust gas recirculation (EGR) loop such that at least one of the combustion cylinders is an EGR cylinder that generates an EGR stream carried only by the EGR loop, comprising:
receiving current combustion charge data representing at least air, fuel and EGR components of the combustion charge; estimating the ignitability of the combustion charge based on the combustion charge data; determining whether the current ignition energy of the ignition system is sufficient to ignite the charge based on at least data representing whether the engine is in cold start mode and further based on the results of the estimating step; and if the current energy of the ignition system is not sufficient to ignite the charge, increasing the amount of hydrogen in the EGR stream; wherein the step of increasing the amount of hydrogen in the EGR stream is performed in at least one of the following ways: providing a more rich air-fuel ratio to one or more of the EGR cylinder(s), by providing post-combustion fuel injection to one or more of the EGR cylinder(s) for one or more engine cycles, by injecting hydrogen into the EGR stream, or by injecting fuel into the EGR stream and using a reformer catalyst to generate hydrogen from this injected fuel.