1.2 ENGINE CLASSIFICATIONS

There are many different types of internal combustion engines. They can be classified by:

1. Appplication. Automobile, truck, locomotive, light aircraft, marine, portable power system, power generation.

2. Basic engine design. Reciprocating engines (in turn subdivided by arrangement of cylinders: e.g., in-line, V, radial, opposed), rotary engines (Wankel and other geometries)

3. Working cycle. Four-stroke cycle: naturally aspirated (admitting atmospheric air), supercharged (admitting precompressed fresh mixture), and turbocharged (admitting fresh mixture compressed in a compressor driven by an exhaust turbine), two-stroke cycle: crankcase scavenged, supercharged, and

turbocharged.

4. Valve or port design and location. Overhead (or I-head) valves, underhead (or L-head) valves, rotary valves, cross-scavenged porting (inlet and exhaust ports on opposite sides of cylinder at one end), loop-scavenged porting (inlet and exhaust ports on same side of cylinder at one end), through- or uniflowscavenged (inlet and exhaust ports or valves at different ends of cylinder)

5. Fuel. Gasoline (or petrol), fuel oil (or diesel fuel), natural gas, liquid petroleum gas, alcohols (methanol, ethanol), hydrogen, dual fuel.

6. Method of mixture preparation. Carburetion, fuel injection into the intake ports or intake manifold, fuel injection into the engine cylinder.

7. Method of ignition. Spark ignition (in conventional engines where the mixture is uniform and in stratified-charge engines where the mixture is non-uniform), compression ignition (in conventional diesels, as well as ignition in gas engines by pilot injection of fuel oil)

8. Combustion chamber design. Open chamber (many designs: e.g., disc, wedge, hemisphere, bowl-in-piston), divided chamber (small and large auxiliary chambers; many designs: e.g., swirl chambers, prechambers)

9. Method of load control. Throttling of fuel and air flow together so mixture composition is essentially unchanged, control of fuel flow alone, a combination of these.

10. Method of cooling. Water cooled, air cooled, uncooled (other than by natural convection and radiation)

Ref

Internal Combustion Engine Fundamentals, John B. Heywood