But there was a time when the automobile we now consider something very normal was only a dream. Engineers and inventors of all kinds were trying to figure out how to build a moving vehicle people could sit in to go from one place to another. One of these inventive gentlemen was Karl Benz, a German engineer. In 1885 Karl figured out how to motorize a three-wheeled cart by fixing a small gasoline engine to it. Most people think this was the birth of the motor vehicle, but they may have forgotten about another German engineer named Nikolaus Otto. Almost 20 years before Karl invented what was basically a go kart, Nikolaus designed something that is still in use by car manufacturers – the four stroke engine. While it’s changed over time and has been improved, it remains the foundation of much of what makes cars work. It ran on gas, which is an energy producing, natural substance. Nikolaus’ engine built on the attempts of other inventors by compressing the gas needed to fuel them. This resulted in more efficient, less wasteful use of the fuel, which was very expensive at that time. (We’ll talk more about how Nikolaus’s invention works in a moment). Another very important person (whose name will sound familiar) is Rudolf Diesel. In 1893, Rudolf patented the compression ignition engine (which is named a diesel engine, after Rudolf). In 1900, his version of the car, fuelled by peanut oil, was a huge attraction at that year’s World’ Fair. So, cars have been around since the early 20th Century, but it wasn’t until about the 1950s they became such an important part of modern life. Until then, cars were seen as luxury items that only people with a lot of money could afford. As time when by, though, cars became available to almost everyone. They’re now seen as everyday items and even a modern necessity. While we all know what cars do and most of us are used to riding around in them, not many of us know how they work. What makes them go? It’s not magic! Its mechanics and physics that make the wheels go around. Let’s explore the mysterious life of cars and the basics about how they work.
As we found out above, Nikolaus Otto created an engine that could make better use of fuel. Many others had designed engines, but he believed he could produce one that wouldn’t be as wasteful and so, less expensive to run. In Otto’s engine, the mechanism for burning fuel to make the moving parts of the vehicle come to life was a four step process. Intake, compression, power and finally, exhaust were the logical sequence he came up with to make the maximum use of fuel to power a vehicle.Each of four strokes of a piston head inside a sealed chamber performs a very specific purpose, and each of them makes a full turn around a central component (called a crankshaft) to produce a stroke). As the piston moves up and down in a circular motion, this is what happens:
Intake: In the first stroke, vacuum pressure (the application of force which pulls a substance inward) sucks a mixture of air-fuel into the cylinder where the piston is located.
Compression: In the second stroke, the air-fuel mixture is compressed (this makes it take up less space through the use of pressure) to prepare for ignition (the spark that heats things up to create energy).
Power: The third stroke is where the magic happens! This is where the compressed fuel is litby the spark plug (if the engine uses gas) or heat (if the engine uses diesel – that’s named after Rudolf Diesel too). This is when all the parts of the car start to move, because the energy in the fuel has been lit upand is now ready to power the car with thermodynamic (literally – heat that makes moving parts spring into action) energy.
Exhaust: What goes in must come out, so stroke four sends the fuel that’s been burned to power the car out through its exhaust pipe, out of the car.
So what’s so special about petroleum that it makes cars move?
You may have noticed above that Nikolaus Otto was a pioneer in fuel efficiency because gas was so expensive in
those days. So what changed?
Crude oil is pumped out of the earth to become energy. As far back as the 4th Century, China figured out a way to get oil from the ground. Persia began extracting crude oil the in 9thCentury, using it for military purposes and lanterns. But in North America, the first oil wells were established in the mid-19th Century. Once large scale oil operations began, cars became more viable, because there was a plentiful source of energy to fuel them. But what is it? Basically, crude oil is the earth’s energy. Once refined, it becomes a variety of fuels, like gasoline and diesel. Its basic chemical makeup is hydrocarbons (carbon and hydrogen mixed together with a little oxygen). When you burn it (as you do with the four stroke engine), energy is created when its molecules are cracked open. Now released, a chemical reaction takes place in which those cracked open molecules are transformed into heat when it meets the abundant oxygen in the air. This is called combustion (the very rapid production of heat and/or light when some substances are combined with oxygen). That’s how it becomes energy. When it’s fed into a mechanism like Nikolaus Otto’s four stroke engine, the energy is released into the machine being powered (in this case, a car) when the spark plug lights it up, releasing energy. That’s when kinetic (moving) energy is created, which makes the car move through space. It’s pretty amazing to think about a world without cars, before all these great inventors found a way of creating a means to power them. Because of people like Nikolaus Otto, Karl Benz and Rudolf Diesel, the horseless carriage, propelled by energy produced by harnessing chemical properties and engineering principles, is a part of our daily life. It’s not magic, but there’s something magical about guys this smart!
Karl Benz: https://en.wikipedia.org/wiki/Karl_BenzRudolf Diesel: https://en.wikipedia.org/wiki/Rudolf_Diesel
Nicholas Otto: http://ae-plus.com/milestones/nicolaus-otto-developed-the-four-stroke-combustion-engine
A cool animation, showing how a four stroke engine works: https://www.youtube.com/watch?v=OGj8OneMjek