Spark-ignition engine

About: Spark-ignition engine is a research topic. Over the lifetime, 4352 publications have been published within this topic receiving 66550 citations.

Cylinder direct-injection type spark ignition engine

Abstract: PURPOSE:To optimize an interval between fuel injection timing of fuel injection and ignition timing in compression stroke and obtain excellent ignition and combustion by delaying the ignition timing when knocking is occurred, and also delaying the injection timing of the fuel injection in the compression stroke. CONSTITUTION:In the case of operating an engine, in the first place, the total fuel injection volume Q is calculated by means of an ECU 30 according to engine rotation speed and accel opening, and next, compression stroke fuel injection volume Qc is calculated according to the total fuel injection volume Q. Furthermore, according to a map, map ignition timing thetaigM is calculated. Next, a judgment is made on whether or not knocking is occurred, and when the knocking has been occurred, actual ignition timing thetaig is decreased by theta. Next, a judgment is made on whether or not Qc>0 is realized, and when Qc>0 is realized, that is, when compression stroke injection is carried out, compression stroke fuel injection timing thetac is calculated so that the compression stroke fuel injection timing can be delayed. Furthermore, a judgment is made on whether or not the compression stroke fuel injection volume Qc exceeds the maximum value QcMAX, and in the case of Qc>QcMAX, Qc is set as QcMAX.

Combustion Characteristics of Ammonia in a Modern Spark-Ignition Engine

Abstract: Ammonia is now recognized as a very serious asset in the context of the hydrogen energy economy, thanks to its non-carbon nature, competitive energy density and very mature production, storage and transport processes. If produced from renewable sources, its use as a direct combustion fuel could participate to the flexibility in the power sector as well as help mitigating fossil fuel use in certain sectors, such as long-haul shipping. However, ammonia presents unfavorable combustion properties, requiring further investigation of its combustion characteristics in practical systems. In the present study, a modern single-cylinder spark-ignition engine is fueled with gaseous ammonia/air mixtures at various equivalence ratios and intake pressures. The results are compared with methane/air and previous ammonia/hydrogen/air measurements, where hydrogen is used as combustion promoter. In-cylinder pressure and exhaust concentrations of selected species are measured and analyzed. Results show that ammonia is a very suitable fuel for SI engine operation, since high power outputs were achieved with satisfying efficiency by taking advantage of the promoting effects of either hydrogen enrichment or increased intake pressure, or a combination of both. The performances under NH3 fueling compare well with those obtained under methane operation. High NOx and unburned NH3 exhaust concentrations were also observed under fuel-lean and fuel-rich conditions, respectively, calling for additional mitigation measures. A detailed combustion analysis show that hydrogen mainly acts as an ignition promoter. In the engine, pure ammonia combustion is assumedly mainly driven by the ignition kinetics of ammonia and the flame response to turbulence rather than by the laminar burning velocity.