The Power Within

The Evolution and Mechanics of Combustion Engines

Throughout centuries, the combustion engine has been pivotal in advancing human travel, exploration, and territorial expansion. Originating as early as the late 1700s with the gas turbine's invention, its significance was cemented when Nicolaus Otto patented the concept in 1876, which was further enhanced by Gottlieb Daimler and Wilhelm Maybach in 1885.

Ever since, the combustion engine has been the cornerstone of gasoline engines and the broader scope of modern transportation, propelling cars, boats, aircraft, and more. Despite the shift towards hydrogen-powered engines and electric vehicles (EVs), the profound influence of the combustion engine on human progress cannot be overstated. Understanding its impact requires knowledge of its operation. Modern internal combustion engines are primarily of two types: spark-ignition and compression-ignition, each with subtle yet significant differences.

A Combustion Engine Utilizes a Combination of Heat, Pressure, and Fuel to Pump Itself

Before delving into the variants, it's essential to understand the workings of combustion engines. While they may appear complex at first glance, when reduced to their fundamental scientific principles, they are quite straightforward. The power generated by a combustion engine is derived from a combination of heat and pressure, generated through a series of pistons. An engine block contains several cylinders, topped off with an air-tight seal, within which are pistons. All of these pistons are connected to a crankshaft, which spins the gears in a car's powertrain and makes the wheels turn, for example.

Within each of the cylinders is a constant, compact science experiment. An intake valve pulls fuel from a connected fuel tank along with air from outside and sprays it underneath the piston, which presses down tightly to compress it. This

compressed fuel and air is then heated. This combination of heat and pressure causes the mixture to ignite, creating a tiny explosion. The force from this explosion pushes the piston back up, and force from the push is transferred to the crankshaft, generating power.

Four-Stroke and Two-Stroke Designs

Beyond the primary types of combustion engines, the system can also be categorized by the number of strokes in the energy generation cycle. Here, a "stroke" denotes the phases of the energy generation cycle. Engines are typically designed as either four-stroke or two-stroke.

A four-stroke engine operates in four phases: intake of air and/or fuel, compression of the piston, ignition to produce power, and expulsion of exhaust. These phases are essential for generating energy in the crankshaft. Conversely, a two-stroke engine simplifies the process by merging the phases of a four-stroke engine into two steps. The first stroke involves the piston rising to draw in and compress air and/or fuel, followed by ignition. The second stroke sees the piston descend to expel the exhaust.

Although both engine types can be designed as four-stroke or two-stroke, spark-ignition engines commonly use the four-stroke model, while compression-ignition engines frequently employ the two-stroke model. Two-stroke engines, with their lighter build and quicker operation, are suitable for simple machines like scooters, but environmental concerns have diminished their prevalence. On the other hand, four-stroke engines, which run smoothly at lower RPMs and are more fuel-efficient, are preferred for consumer vehicles.