Lenoir (1822-1900) designed and innovated first sufficient and useful engineduring the 1860s. Then, many researchers try to invent many different enginedesign. But, most of the engine only produce power about 4.5kW (6hp) andreached mechanical efficiency up to 5%.
Nicolaus A. Otto (1832-1891) and EugenLangen (1833-1895) were most famous engine creators at that period. Otto-Langenengine reached mechanical efficiency up to 11% compared to any other enginedesign. During this decade, the enginewas functioning on the same basic four-stroke cycle (Otto cycle) as advancedautomobile engine start to grow. Otto engine was built in 1876 and givenrecognition as best engine prototype.
1 Thefollowing is an explanation of spark ignited four-stroke cycle engine: 1. IntakeStroke- As the exhaust valve closed and intake valve open, the piston movesfrom TDC to BDC. The vacuum generated the volume increase in the cylinder.
Air-thrust into cylinder due to the pressure difference between intake systemwhich has atmospheric pressure and vacuum inside the cylinder. Gasoline will beadded to the air flow through the intake system. 2. CompressionStroke- The intake valve closed as the piston passes BDC. Then, the piston moves back to TDC while intake and exhaustvalve closed.
During this process, the air-fuelmixture is compressed, increasingtemperature and pressure of the cylinder. In a normal present spark-ignited gasoline engine, the compression ratio is about 8:1 to11:1. 3. Expansionor Power Stroke- Spark ignited as the piston nears the TDC and combustionprocess started to occur.
Combustionprocess alters the air-fuel mixture into exhaust gas and increases the cylinderpressure and temperature. High pressureis generated by the combustion process push the piston from TDC to BDC. Thiscycle produces useable work and cylinder pressure and temperature start todecrease. 4. ExhaustStroke- Exhaust gasses fill the cylinder as the piston reached BDC. Then,exhaust valve opened to enable the exhaust gases to travel to the exhaustmanifold. The piston travels from BDC to TDC in the exhaust stroke.
Thisprocess pushes remaining exhaust gases out of the cylinder.