OIL ENGINES Although for decades the internal combustion} engine was neglected while the attention of the engineer was centered on the steam engine, still the former had been built and actually used long before Watts constructed his atmospheric steam engine. Because of defects of operation in the internal combustion engine that seemed impossible of solution, the steam engine took precedence, and it was only during the latter part of the nineteenth century that the gas engine began to come into commercial favor.
several scientists had suggested the use of gunpowder in a closed vessel as a source of power, Huyghens appears to have been the first who actually built an internal combustion engine (1680). His design embodied an open ended cylinder with a piston. The powder was exploded when the piston was at the bottom of the cylinder: the explosion forced the piston upward. The gases were expelled through leather valves, and the cooling of the gases that remained in the cylinder created a vacuum. The atmospheric pressure, acting on the piston, forced it downward into the cylinder, doing work by its movement. Many structural defects caused the abandon ment of this design.
Barber's Producer Gas internal combustion engine was practically ignored until 1791 when an Englishman, John Barber, built an engine which made use of gas distilled from coal. The essential features of Barber's engine were the use of a mixing chamber wherein the air and producer gas were mixed and ignited, and the employment of a paddle-wheel against the blades of which the gases, issuing from the chamber, im pinged. This machine was in reality a gas turbine rather than a gas engine, and several modern engineers have worked on the design of a gas turbine along the same lines. Barber patented this engine in 1791.
a number of experimenters interested themselves in the problem of building an internal combustion engine, Lenoir was the first to manufacture a marketable engine in 1860.
The Lenoir engine, Fig. 1, was double acting; the valves were of the flat-ported type, somewhat along steam engine practice, being operated by eccentrics. The gas and air were mixed in
the inlet valve and passed into the cylinder under the suction effect of the retreating piston. When the piston was almost halfway in its stroke, the charge was ignited. The pressure then rose to the vicinity of 75 pounds. The piston continued to the end of its stroke, being acted upon by the gas pressure. The exhaust valve then opened, and the burnt products were pushed out by the piston on the return stroke. Hundreds of these engines were placed in commercial use, but the gas consumption was high, the efficiency being but little above 4 per cent.
Otto's this' time, 1866, Otto, in Germany, designed an engine with a free piston. In this engine, which was built vertically with the cylinder below the crankshaft, the piston was forced upward by the explosion. The weight of the piston then caused it to descend into the cylinder, assisted by the vacuum formed by the cooling of the gases. In descending, the piston engaged a rack which turned the crankshaft through a clutch. The inertia of the flywheel started the piston on the upward stroke, and the vacuum formed drew in a gas charge. This charge was exploded when the piston was partly advanced on the upstroke. It is apparent that this embodied the same principles as did Lenoir's engine.
Beau de Rochas.—In 1862 Beau de Rochas, a Frenchman, proposed the cycle that is at present used by the majority of gas engines. His proposal, although he never actually built an engine, was as follows: The essential factors in obtaining high efficiency are: first, the highest possible compression pressure at the moment of ignition; second, the greatest possible expansion of the gases after combustion.
To achieve the desired efficiency in an engine, de Rochas proposed that an engine should operate on the four-stroke cycle principle, having the following events: Stroke 1. Draw in the air and gas charge.