Diesel Engine

"Early Theories and Successes Nicholas Sadi Carnot, a French scientist, formulated theories on the thermodynamics of engine operation that would influence both Otto, and to a greater extent, Diesel. In papers published in 1824, Carnot introduced the idea of a cycle in heat engine operation. The cycle consisted of a series of steps that would both produce power and return the engine to its original position. Carnot theorized that a piston could be driven back and forth in a cylinder by first heating and then cooling a gas trapped inside the cylinder. The controlled expansion of the gas as it is heated and the contraction of the gas as it cooled would drive the piston. In theory, Carnot’s engine was 100% efficient. All heat generated would be turned into useful power. Carnot admitted that a 100% efficient engine was an impossibility, but it was an idea that would intrigue a young Rudolf Diesel over fifty years later. Although Carnot never attempted to build a working model based on his theory, his ideas on engine cycling and the use of an expanding gas to move a piston were major contributions to small engine design. In 1860, Etienne Lenoir demonstrated a double-acting internal combustion engine fueled with street lamp gas. It used many of the principles found in modern engines. A mixture of air and lamp gas was drawn into one end of a long cylinder that housed a piston connected to a crank- shaft. The mixture was ignited by an electric spark. The resulting explosion drove the piston along the cylinder to the end of its stroke. The process was then repeated at the other end of the cylinder with the explosion occurring on 14 Diesel Technology Figure 1-6. Diesel injection pumps are quite complex and must be built to exacting tolerances. (Caterpillar) This sample chapter is for review purposes only. Copyright © The Goodheart-Willcox Co., Inc. All rights reserved. the opposite face of the piston. This drove the piston back to its original position. On its return trip, the piston helped clear the cylinder of the waste gases remaining from the previous explosion. The two firings per cycle were timed to occur at 180 ° of crankshaft rotation apar"