Automotive spark-ignited direct-injection gasoline engines

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Many new mixture-preparation and combustion-control
strategies for direct-gasoline-injection, four-stroke, sparkignition
engines have been proposed and developed since
1990 by automotive companies, fuel system manufacturers
and research institutions. Currently, five automotive companies
have already put this engine technology into production
in both the Japanese and European markets. These types of
engines are classified as third-generation GDI engines [50].
Based on the information available in the literature, the key
features of these specific GDI engines that have been developed
during this recent time period are briefly summarized
in Table 2 and the details of some of these combustion
systems are given below.
6.2. Mitsubishi combustion system
F. Zhao et al. / Progress in Energy and Combustion Science 25 (1999) 437–562
Fig. 103. The cutaway of the Mitsubishi I4 GDI engine [194].
The Mitsubishi GDI combustion system was discussed in
detail by Kume et al. [20], Ando et al. [15–19], Kuwahara
et al. [49,134,207,245,246], Kamura and Takada [194],
Iwamoto et al. [50,51], Yamamoto et al. [247], Yamaguchi
[248–251,370], McCann [46], Auer [252], Schreffler
Fig. 104. The Mitsubishi GDI control map [50,51].
[253,352,353], Demmler [254], Lewis [328], Ward [364]
and Treece [362]. The schematic of the engine layout, the
engine cutaway, and the piston geometry are shown in Figs.
101–103. The combustion mode calibration is illustrated in
Fig. 104. An early injection strategy is utilized for engine
operation at high loads. In most of this zone, the engine uses
a stoichiometric mixture and is operated at a slightly rich
condition at full load. For the lowest-load conditions in this
zone, the engine operates with a homogeneous, lean mixture
for further improvement of fuel economy. The air–fuel
mixture is in the range of 20–25. The first GDI engine
that was launched in Japan in 1996 is based on the production
4G93 SI engine, using dual overhead camshafts, four
valves per cylinder, in an inline four-cylinder configuration.
The main differences from the 4G93 are the cylinder head
and piston design, and a high-pressure fuel pump and injectors.
In the Mitsubishi dual-catalyst system, the first catalyst
uses pure iridium, which works during the lean period. A
normal platinum catalyst is mounted downstream to catalyze
the gases during non-lean periods. Mitsubishi’s Galant
and Legnum, the station wagon variant, are powered by this
GDI engine. The fuel economy provided by the Mitsubishi
4G93 GDI engine was reported to show a significant
improvement when compared to the comparable displacement,
conventional PFI engine on the Japanese urban test
cycle, while the 0–100 km/h acceleration time is enhanced
by 5%. Due to the inherent in-cylinder charge cooling and
improved intake port design, the volumetric efficient of the
Mitsubishi GDI engine is increased by 5% over the entire
engine operating range. In combination with an increased
compression ratio of 12, the total power output is increased
by 10% [50,51], which is shown in Fig. 105. The principal
features of Mitsubishi 1.8L four-cylinder GDI system are:
• four cylinders;
• four-valve DOHC pentroof combustion chamber;
• bore × stroke : 81 × 89 mm;
• displacement—1864 cm 3 ;
• compression ratio—12:1;