What are engines?
Motors are mechanisms that are capable of transforming one type of energy (electric, combustion, etc.) into mechanical energy. This transformation makes it possible to carry out a task that makes a system or machinery work. Motors are usually made out of cast aluminum or steel parts, which are ideal for supporting and counteracting the heat generated in the mechanical process of energy transformation.
What are the characteristics of engines?
There are different types of engines, and each has its own characteristics. Still, there are some elements they all have in common:
- Stability: the ability to keep running at high speeds without consuming an excessive amount of fuel or electrical energy.
- Power: the work engines generate in a certain amount of time at a specific speed. An engine’s power is expressed in kW (kilowatts), according to the International System of Units; in HP (horsepower) in Anglo-Saxon systems; or metric horsepower.
- Performance: the output obtained between the useful power of the engines and the power absorbed.
- Engine torque: the moment of force that affects the axis of the engines and which determines their rotation.
- Rated speed: the number of revolutions per minute at which the engines spin.
What types of engines are there?
According to the type of energy they require to fulfill their functions, engines can be classified as:
- Electric motors: those whose work is made possible by an electric current that can be stored in rechargeable batteries. They can also be reversible in nature, meaning they convert mechanical energy into electrical energy, operating as generators. There are even traction systems that combine both tasks.
Electric motors can be powered by direct current (DC) sources, or those that come from batteries, solar panels, or installations inside appliances that use this system; or by sources of alternating current (AC), meaning it is taken directly from the power grid, plant alternators, or other two-phase or three-phase currents such as power inverters.
This type of motor is more advantageous in terms of environmental sustainability compared to combustion engines because its carbon dioxide emission is minimal, besides not emitting heat or noise.
- Thermal engines: use the thermal energy coming from the combustion of a fluid, either diesel or gasoline, to convert it into mechanical energy. The heat needed for running the machine is generated thanks to the chemical reactions of combustion. Heat engines can, in turn, be classified into:
- External combustion engines: their combustion process occurs outside the engine, and the released heat is transmitted to an intermediate fluid, which is what generates mechanical energy. This is the case with the steam engine, where the intermediate fluid is water vapor, and the place where combustion occurs is the boiler, which is located outside the engine.
- Internal combustion engines: the combustion process occurs inside the engine itself, in an internal chamber where the gases that produce the machine’s operation are generated. The most common are gasoline engines. They have four strokes (intake, compression, combustion, and exhaust) in their operation, where gasoline is mixed with air before being sucked into the cylinder to produce combustion. There are also diesel engines, which use combustion injectors to bathe the cylinder with fuel. This type of engine doesn’t have a spark plug, unlike gasoline engines, so it needs a higher compression for the fuel and air to mix and the engine can start.
- Hybrid engines: these use two different types of power: electric and thermal, through gasoline, which are combined to start a vehicle or machine. They can work together, either separately or in parallel, and their aim is to maximize the performance of fuels such as gasoline while keeping the battery charged so that it doesn’t need to be charged again.
- Jet engines: these are based on Newton’s Third Law; they consist of a gas turbine used to discharge jets of fluids at high speed and cause the propulsion of a machine. A few examples of this type of engine are turbojets, rockets, and pulse jets.