Page 13 - Piston Engine-Based Power Plants

6 Piston Engine-Based Power Plants

One of the first was designed by Belgian engineer Jean Joseph
Etienne Lenoir. His single cylinder engine was an adapted steam recip-
rocating engine that was fired with fuel gas that was ignited inside the
cylinder using ‘jumping sparks’, an early electrical ignition system.
Lenoir’s engine was derived from a double-acting steam engine in
which steam is used to drive the piston in both directions. (In the
Newcomen engine steam drives it in one direction and atmospheric
pressure in the other.) Lenoir engines were primarily used for station-
ary applications such as pumping but Lenoir did also develop carriages
driven by his engine, some using liquid hydrocarbon fuel.

The Lenoir engine was primitive and noisy but it did work and it
inspired the German engineer Nikolaus August Otto, who together with
his brother built a copy of the Lenoir engine in 1861. The brothers tried
to obtain a patent for their engine in Prussia, but failed. The same year
they experimented with a charge of fuel and air that was compressed
instead of at atmospheric pressure. Although this compressed charge
engine only ran for a short time before failing, this idea was to prove an
essential component of the internal combustion engine.

By 1864 Otto had set up a partnership with Eugen Langen to
develop engines. The first Langen Otto engine was an atmospheric
engine that used internal combustion to drive the piston through the
first part of the cycle while the force of atmospheric pressure returned
the piston as in the Newcomen engine. This proved a successful inter-
nal combustion engine but it developed only low power and required
significant head room to operate.

Otto continued to work on improvements and in 1876 the company,
now called Deutz AG Gasmotorenfabrik, developed the four-stroke,
compressed charge engine based on an engine cycle that is now known
as the Otto cycle. This forms the basis for all the spark ignition engines
that are in use today. One of the main differences between this and
earlier engines was that it did not rely on atmospheric pressure to
return the cylinder after the power stroke. Instead a large flywheel on
the power shaft was used to provide sufficient angular momentum to
complete the cycle. The engine was fuelled with coal gas and used a
live flame to ignite the fuel air mixture at the top of the compression
stroke of the engine.