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Liquid fuel inflow into the cylinder is considered to be an important source of exhaust hydrocarbon (HC) emissions from automotive spark ignition engines. These liquid-fuel-caused emissions are increased significantly during the start up and subsequent warm-up period. This study analyzes the influence of several engine and injector design variables, and fuel parameters, on the in-cylinder liquid fuel behavior. The effect of the following parameters on the characteristics of the fuel droplets entering the cylinder was studied: Fuel volatility, injection timing, intake valve timing, injector type, spray geometry, and spray targeting in the intake port. A Phase Doppler Particle Analyzer (PDPA) was used in a single-cylinder flow visualization combustion engine to assess this in-cylinder liquid fuel behavior. Measurements of fuel droplet characteristics (size and velocity) were taken in selected locations in the vicinity of the intake valve during starting and warm up.

As features in vehicles and their associated loading on the vehicle's power supply increase, the existing 14V power supply system is being pushed to its limits. At some point it will be necessary to provide a complementary higher supply voltage for higher power loads to ensure reliable operation. Industry efforts have been underway to define the next step(s) toward a common architecture. These efforts are currently focused on a dual voltage 14V/42V system with specified voltage limits. A change in the vehicle's power supply voltage and over-voltage specifications have a direct impact on semiconductors. Cost, reliability, available process technology, and packaging are among the areas that are affected. Reducing or eliminating the load dump transient can provide cost reduction, especially for power switching devices. Smart semiconductor switches with integrated diagnostic and protection features provide the potential to replace fuses in the new architecture.

Liquid fuel flow into the cylinder an important source of hydrocarbon (HC) emissions of an SI engine. This is an especially important HC source during engine warm up. This paper examines the phenomena that determine the inflow of liquid fuel through the intake valve during a simulated start-up procedure. A Phase Doppler Particle Analyzer (PDPA) was used to measure the size and velocity of liquid fuel droplets in the vicinity of the intake valve in a firing transparent flow-visualization engine. These characteristics were measured as a function of engine running time and crank angle position during four stroke cycle. Droplet characteristics were measured at 7 angular positions in 5 planes around the circumference of the intake valve for both open and closed-valve injection. Additionally the cone shaped geometry of the entering liquid fuel spray was visualized using a Planar Laser Induced Fluorescence (PLIF) setup on the same engine.

The occurrence of liquid fuel in the cylinder of automotive internal combustion engines is believed to be an important source of exhaust hydrocarbon (HC) emissions, especially during the warm-up process following an engine start up. In this study a Phase Doppler Particle Analyzer (PDPA) has been used in a transparent flow visualization combustion engine in order to investigate the phenomena which govern the transport of liquid fuel into the cylinder during a simulated engine start up process. Using indolene fuel, the engine was started up from room temperature and run for 90 sec on each start up simulation. The size and velocity of the liquid fuel droplets entering the cylinder were measured as a function of time and crank angle position during these start up processes. The square-piston transparent engine used gave full optical access to the cylinder head region, so that these droplet characteristics could be measured in the immediate vicinity of the intake valve.

Current demands for high fuel efficiency and low emissions in automotive powerplants have drawn attention to the two-stroke engine configuration. The present study measured trapping and scavenging efficiencies of a firing two-stroke spark-ignition engine by in-cylinder gas composition analysis. Intermediate results of the procedure included the trapped air-fuel ratio and residual exhaust gas fraction. Samples, acquired with a fast-acting electromagnetic valve installed in the cylinder head, were taken of the unburned mixture without fuel injection and of the burned gases prior to exhaust port opening, at engine speeds of 1000 to 3000 rpm and at 10 to 100% of full load. A semi-empirical, zero-dimensional scavenging model was developed based on modification of the non-isothermal, perfect-mixing model. Comparison to the experimental data shows good agreement.