Environmental Engineering Reference
In-Depth Information
Table 9.3 Main parameters of spark ignition engines
Construction
Operation
Combustion chamber profile
Combustion chamber design
Compression ratio
Spark plug position
Ignition point
Idle stroke-bore relationship to cylinder volume
Mixture generation
Mixture regulation
Valve timing
Internal mixture creation
Injection system
Lean running
9.2.1 Spark Ignition Engines
A spark ignition engine takes in a mixture of air and fuel and compresses it. The
fuel is usually gasoline, but other hydrocarbons such as LPG or CNG are also
becoming more and more common. It uses a spark plug to ignite the mixture when
it is compressed by the piston head in the cylinders.
The efficiency of a spark ignition engine mainly depends on its construction and
operation (see Table 9.3 ).
9.2.1.1 Main Construction Elements
Construction elements determine the design, the size, and the frame conditions of
operations (see Table 9.4 ).
9.2.1.2 Main Operation Parameters
Operation modes can be regulated depending on driving conditions (see
Table 9.5 ). Changes of operation conditions intensively impacts fuel consumption
and exhaust gas emissions.
9.2.2 Self Ignition Engine
In the past, self ignition engines were generally heavier and noisier than spark
ignition engines. The newest models are small and of a very similar size to a spark
ignition engine in the same performance class. On the other side, self ignition
engines are more efficient in fuel consumption and more powerful at lower speeds
than spark ignition engines, but differences are disappearing [ 22 ].
In Europe, sophisticated cars with self-ignition engine have about a 40% share
of the market. The portion in the USA and in other regions of the world is lower
but it is continuously increasing [ 23 ]. Most self-ignition engines operate in road
vehicles, locomotives, construction machinery, tractors, buses, and ships.
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