Jerry Overturf, age 10, of Edgar, Neb., for his question:
WHEN WAS THE FIRST DIESEL ENGINE MADE?
Diesel engines have what is called a high thermal efficiency. This is an ability to convert the stored chemical energy in the fuel into mechanical energy, or work. A diesel engine burns cheap fuel and can perform heavy work under highly overloaded conditions. This is why they are used for heavy duty work, such as powering locomotives, buses and huge trucks.
A diesel engine is a type of internal combustion engine used chiefly for heavy duty work. The engine is often used to power ships and run the generators of electric power stations.
The diesel engine is a compression ignition engine. When air confined in a cylinder is suddenly compressed, the temperature of the air rises. In a diesel engine, each piston compresses air in a cylinder. Fuel is injected and the heat of the air makes it ignite.
A German engineer named Rudolf Diesel invented the engine in 1893. His first engine exploded and almost killed him, but it proved that fuel could be ignited without a spark. He operated his first successful engine in 1897. Diesel engines burn fuel oils which require less refining and are cheaper than higher grade fuels such as gasoline. During the combustion process, the stored chemical energy in the fuel is converted to thermal or heat energy.
In a diesel engine, the temperature in each cylinder rises as high as 4,500 degrees Fahrenheit. The temperature creates pressures of 1,500 pounds per square inch and it pushes against the tops of the pistons, forcing them to the other end of their cylinders. The pistons are connected by a rod or other suitable connecting mechanism to a crankshaft which they turn.
There are two main types of diesel engines: The four stroke cycle engine and the two stroke cycle engine.
In a four stroke engine, the first downstroke draws air into the cylinder and the first upstroke compresses the air. The second downstroke is the power stroke while the second upstroke exhausts the gases produced by combustion. This engine requires exhaust and air intake valves. In a two stroke engine, the exhaust and intake of fresh air happen through openings in the cylinder near the end of the down, or power, stroke. The one upstroke is the compression stroke. Valves are not needed in a two stroke engine.
A two stroke engine has twice as many power strokes per cycle as four stroke engines, and for this reason they are often used where high power is needed in a small engine. The two stroke diesel engine was developed in Great Britain by an engineer named Sir Douglas Clerk.