Gas Engine Patents of Note

By Staff
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A drawing from August Otto’s 1877 U.S. patent, no. 194,047, for his “Improved Gas-Motor Engine.” It was the world’s first practical 4-stroke engine design.
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By the mid-1860s, the race was on to develop and perfect a
gas-powered engine. Although steam engines had been providing the
power to fuel a rapidly industrializing world, they were not
without their limitations: Chief among them, the requisite for a
large boiler to hold water and fuel to heat the water to steam.
Engineers knew that if they could control an explosion of fuel
driving a piston, they could create an engine with far-reaching
capacity and application.

In the early 1860s, German engineer Nicolaus August Otto and
industrialist Eugen Langen formed N.A. Otto & Cie, with the
express purpose of designing and building internal combustion
engines. By 1866 their company had produced its first – and in fact
the first – practical gas engine, the Otto-Langen atmospheric
engine. Not unlike firing a cannon ball, the engine worked by
exploding a charge to drive a piston vertically. The piston had a
cogged rack for a connecting rod, which engaged a pinion gear at
the top of the cylinder to turn a flywheel, translating its linear
force to rotational motion. The suction created by the piston’s
extended rise, along with the piston’s substantial weight, pulled
the piston back down its bore, driving the pinion as it did so.

The Otto-Langen was a commercial success, and along with
versions built under license, it is thought perhaps as many as
5,000 examples were built until production ended in about 1878. It
was, however, noisy and grossly inefficient (the largest, 3 HP
engines stood over 10 feet tall and weighed close to 5,000 pounds),
as there were no real means for controlling the explosion of gas to
drive the piston.

Otto continued experimenting, and in 1876 he designed and built
the world’s first 4-stroke engine. Originally called the Otto
cycle, its design quickly became known for its principal four
strokes of intake, compression, combustion and exhaust.

The patent

Shown here is Otto’s first United States patent for his engine,
no. 194,047, granted Aug. 14, 1877. A reading of Otto’s patent
shows he clearly understood the need to control the point of
ignition and to create a spreading flame front, rather than an
instantaneous explosion, as in the Otto-Langen.

His patent notes the engine’s introduction of “an intimate
mixture of combustible gas or vapor and air … together with a
separate charge of air or other gas, that may or may not support
combustion, in such a manner and in such proportions that the
particles of combustible gaseous mixture are more or less dispersed
in an isolated condition … so that on ignition, instead of an
explosion ensuing, the flame will be communicated gradually.”

In operation, a slide valve admitted a charge of air, followed
by a concentrated fuel/air charge, and finally opened a channel for
a pilot flame to ignite the concentrated charge, setting off the
process of combustion to drive the piston. A sideshaft controlled
the operation of the slide valve and the exhaust valve (a standard
poppet valve), and a flyball governor driven off the sideshaft
regulated speed. It is a design familiar to every gas engine
collector, its basic construction echoed in every engine that

It’s impossible to overstate the importance of Otto’s engine,
for it set the stage for a new order in motive power, becoming in
short order the dominant form of power for industry, farm and home.
From basic operating principle to working design, it set the
standard for the construction of efficient gas-powered engines and
in the process forever changed the world.

Know of an interesting patent? Contact Gas Engine Magazine
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