The development of four-stroke, spark-ignition engines that are designed to inject gasoline directly into the combustion chamber is an important worldwide initiative of the automotive industry. The thermodynamic potential of such engines for significantly enhanced fuel economy, transient response and cold-start hydrocarbon emission levels has led to a large number of research and development projects that have the goal of understanding, developing and optimizing gasoline direct-injection (GDI) combustion systems. The processes of fuel injection, spray atomization and vaporization, charge cooling, mixture preparation and the control of in-cylinder air motion are all being actively researched, and this work is reviewed in detail and analyzed. The new technologies such as high-pressure, common-rail, gasoline injection systems and swirl-atomizing gasoline fuel injectors are discussed in detail, as these technologies, along with computer control capabilities, have enabled the current new examination of an old objective; the direct-injection, stratified-charge (DISC), gasoline engine. The prior work on DISC engines that is relevant to current GDI engine development is also reviewed and discussed.

The fuel economy and emission data for actual engine configurations are of significant importance to engine researchers and developers. These data have been obtained and assembled for all of the available GDI literature, and are reviewed and discussed in detail. The types of GDI engines are arranged in four classifications of decreasing complexity, and the advantages and disadvantages of each class are noted and explained. Emphasis is placed upon consensus trends and conclusions that are evident when taken as a whole. Thus the GDI researcher is informed regarding the degree to which engine volumetric efficiency and compression ratio can be increased under optimized conditions, and as to the extent to which unburned hydrocarbon (UBHC), NOx and particulate emissions can be minimized for specific combustion strategies. The critical area of GDI fuel injector deposits and the associated effect on spray geometry and engine performance degradation are reviewed, and important system guidelines for minimizing deposition rates and deposit effects are presented. The capabilities and limitations of emission control techniques and aftertreatment hardware are reviewed in depth, and areas of consensus on attaining European, Japanese and North American emission standards are compiled and discussed.

All known research, prototype and production GDI engines worldwide are reviewed as to performance, emissions and fuel economy advantages, and for areas requiring further development. The engine schematics, control diagrams and specifications are compiled, and the emission control strategies are illustrated and discussed. The influence of lean-NOx catalysts on the development of late-injection, stratified-charge GDI engines is reviewed, and the relative merits of lean-burn, homogeneous, direct-injection engines as an option requiring less control complexity are analyzed. All current information in the literature is used as the basis for discussing the future development of automotive GDI engines.

Automotive Spark-Ignited Direct-Injection Gasoline Engines

A Review of Mixture Preparation and Combustion Control Strategies for Spark-Ignited Direct-Injection Gasoline Engines

The invention relates to a piston (10, 110, 210, 310, 410) for an internal combustion engine, comprising a piston crown (11) and a piston skirt (21), said piston crown (11) comprising a piston head (12), a peripheral top land (14), a peripheral annular zone (15) with annular grooves (16, 17, 18) and in the region of the annular zone (15), a peripheral cooling channel (19, 119, 419) which is open towards the base and which is closed by means of a closure element (35, 135, 235, 335, 435). Said cooling channel (19, 119, 419) has a cooling channel base (26, 126, 226, 326, 426) and a cooling channel cover (27), and the piston skirt (21) has two piston hubs (22) which are interconnected by means of two running surfaces (25a, 25b). According to the invention, the inner surface (37), exclusively a running surface (25a) of the piston (10, 110, 210, 310, 410) is connected to the lower side (11a) of the piston crown (11) by means of a connecting bar (38).

Piston for an internal combustion engine

An experimental study of a hydrogen-enriched ethanol fueled Wankel rotary engine at ultra lean and full load conditions

Effect of hydrogen addition on combustion and emissions performance of a gasoline rotary engine at part load and stoichiometric conditions

Cycle-resolved measurements of the fuel concentration near a spark plug in a commercial rotary engine were performed. An in situ laser infrared (IR) absorption method was developed using a spark plug sensor and a 3.392-μm He–Ne laser as the light source. This wavelength coincided with the absorption line of hydrocarbons. The newly developed IR spark plug sensor had a higher signal-to-noise ratio than its previous version due to the optimization of its quartz lens and two optical fibers. The new sensor provided quantitative cycle-resolved fuel concentration measurements around the spark plug with a high temporal resolution. At lean preset air/fuel (A/F) ratios, fuel was mixed with the surrounding air gradually by the rotor motion in the plug hole of the rotary engine. Strong mixture inhomogeneities were measured during the compression stroke; the magnitude of these inhomogeneities decreased throughout the compression stroke. Cycle-resolved measurements were made to investigate the effects of the fuel concentration near the spark plug on the combustion characteristics of the commercial rotary engine. There was a strong correlation between the fuel concentration measured with the spark plug sensor and the combustion characteristics during the initial combustion period, which occurred faster when conditions were slightly richer than stoichiometric near the spark plug. The indicated mean effective pressure (IMEP) was slightly related to the A/F ratio near the spark plug. It was possible to measure the cycle-resolved A/F ratio near the spark plug and investigate its cycle-to-cycle fluctuations to achieve stable operation using the newly developed spark plug sensor.

Cycle-resolved measurements of the fuel concentration near a spark plug in a rotary engine using an in situ laser absorption method

Hydrogen rotary engines are promising power sources for the future hydrogen society, and improving their thermal efficiency helps propel tomorrow's car farther. This research looked into the combustion process to reduce fuel consumption. Primary studies of combustion duration and location showed that increasing the local mass burning rate in the L-side of the combustion chamber by generating turbulence was beneficial. Experiments with optical and real rotary engines proved that turbulence effectively increased mass burning rate in L-side and consequently engine's thermal efficiency and its lean limit.

Amelioration of Combustion of Hydrogen Rotary Engine

A study of a direct-injection stratified-charge rotary engine for motor vehicle application

An exhaust gas purifying system, which is equipped with a catalytic converter having
a NOx absorbent capable of absorbing NOx emissions in an excessively oxygen concentrated
atmosphere and releasing NOx emissions absorbed therein in response to a drop in oxygen
concentration of the exhaust gas, estimates a level of NOx absorption of the NOx absorbent
and, when the level of NOx absorption has reached a predetermined level, while controlling
an air-to-fuel ratio to converge at an approximately stoichiometric air-to-fuel ratio, divides
the amount of fuel that is to be sprayed into two parts for early split fuel injection which is
made at the beginning of an intake stroke and later split fuel injection which is made at an
end of a compression stroke following the intake stroke. While the engine operates in a high
engine load region, an intake throttle valve is closed so as to decrease the amount of intake
air that is introduced into the engine.

Ryoji Kagawa

Papers

Cycle-resolved measurements of the fuel concentration near a spark plug in a rotary engine using an in situ laser absorption method

Amelioration of Combustion of Hydrogen Rotary Engine

A study of a direct-injection stratified-charge rotary engine for motor vehicle application

Exhaust gas purifying system for diesel engine

Simultaneous Observation of Combustion in Optical Rotary Engine by Bottom View and Side View