Diesel engine.
Diesel cycle

Endothermic engine

Types of Engines

Types of engines

A motor or motor is a machine designed to convert a form of energy into  mechanical energy . An engine can be classified into a category according to two criteria: the form of energy it accepts to create movement and the type of movement it produces.

As a general rule, engines have an axle, which in rotary offset and through mechanical devices such as drive gears. The exceptions are rocket motors and linear motors . Nowadays, combustion engines and electric motors are of the utmost importance.

Heat Engine or Heat Engine

In thermal mechanics, a thermal engine is a physical or theoretical device capable of exchanging heat and working with the environment or with other physical systems. Thermal machines are typically cyclical and, therefore, are physically described by a thermodynamic cycle. The name of a thermal machine is usually that of the associated thermodynamic cycle . Some have names like diesel engine , Otto engine , turbine engine or  steam engines .

The combustion engines are  thermal engines driven by the heat of a combustion process.

Internal Combustion Engine

The internal combustion engine is a motor in which the combustion of a fuel (usually fossil fuels) occurs with an oxidant (usually air) in a combustion chamber. In an  internal combustion engine , the expansion of high temperature and high pressuregases , which are produced by combustion, applies force directly to engine components, such as  pistons or turbine blades or a nozzle, and moving it at a distance, it generates mechanical work.

External Combustion Engine

External combustion engines are a type of engines in which the fuel is used to heat a working fluid, through which the conversion of  thermal energy into mechanical work is carried out . The alternative  steam engine , the steam turbine and the Stirling enginebelong to this category.

An external combustion engine is a thermal engine in which an internal working fluid is heated by combustion from an external source, through the engine wall or a heat exchanger. The fluid then, as it expands and acts on the mechanism of the motor, produces movement and usable work. Then, the fluid is cooled, compressed and reused (closed cycle), or (less frequently) discharged, and cold fluid is introduced (open-cycle air motor).

The working fluid can be a gas, vapor or a liquid, as it happens in a Stirling engine , a steam engine or an organic liquid respectively. The fluid can be of any composition. Gas is by far the most common, although sometimes even single-phase liquid is used. In the case of the  steam engine , the fluid changes the phases between liquid and gas.

Combustion Engines with Breathing Air

Combustion engines that breathe air are combustion engines that use oxygen in atmospheric air to oxidize ("burn") the fuel, instead of transporting an oxidant, as in a rocket. Theoretically, this should result in a better specific boost than for rocket engines.

A continuous flow of air flows through the air breathing motor. This air is compressed, mixed with fuel, ignited and expelled as exhaust gas.

Examples of typical air breathing motors include:  reciprocating engine, steam engine , gas turbine, air jet engine, turboprop engine, pulse detonator engine, pulse jet, ramjet, ccramjet, m liquid air cycle engine / SABRE reaction engines.

Non-combustible Heat Engines

Some engines convert heat from non-combustible processes into mechanical work, for example, a nuclear power plant uses the heat of nuclear reaction to produce steam and drive a steam engine , or a gas turbine in a rocket engine can be driven by the decomposition of hydrogen peroxide.

Apart from the different sources of energy, the engine is often designed much like an internal or external combustion engine. Another group of non-fuel engines includes thermoacoustic heat engines (sometimes called "TA engines") that are thermoacoustic devices that use high amplitude sound waves to pump heat from one place to another, or use a heat difference to the contrary. induce high amplitude sound waves. In general, thermoacoustic motors can be divided into stationary wave and traveling wave devices.

Non-thermal Motor Chemically Fed

Non-thermal motors are usually driven by a chemical reaction, but they are not thermal motors . Examples:

  • Molecular engine - engines found in living beings.
  • Synthetic molecular engine.

Electric Motor

The  electric motor is a rotating electric machine that transforms the input electrical energy, applied to the supply terminals, into  mechanical energy in the production shown available on the motor shaft. This type of electrical machine is based, in a similar way to what happens in the electrical generator , the electromagnetic forces that interact between a current system and a magnetic field.

The electric motors can be powered by direct current (for example, a portable battery powered device or motor vehicle), or by alternating current from a central electrical distribution network.

The smallest motors can be found in electric wristwatches. Medium-sized engines with highly standardized dimensions and characteristics provide a convenient mechanical power for industrial uses. Larger electric motors are used for the propulsion of large vessels, and for purposes such as pipe compressors, with ratings of thousands of kilowatts.

The electric motors can be classified by the electric power source, by its internal construction and by its application.

Physical Power Motor

Some engines work with kinetic or potential energy, for example, some funiculars, gravity plane carriers and cable cars have used the energy of water or moving rocks, and some watches have a weight that falls under gravity. Other forms of potential energy include compressed gases (such as pneumatic motors), springs (watchmaking motors) and elastic bands.

Pneumatic Motor

The pneumatic motor, also called a compressed air motor, is a particular type of motor that performs mechanical work by exploiting the expansion of strongly compressed air. Pneumatic motors generally convert the compressed air into mechanical work through linear or rotary motion.

The linear movement can come from a diaphragm or from a piston actuator, while the rotary movement is supplied by a pneumatic type vane motor or by a pneumatic pistonmotor . Pneumatic motors have found widespread success in the hand tool industry and continuous attempts are being made to expand their use to the transportation industry.

Pneumatic motors have existed for several centuries in different forms and vary in size, from the turbines of portable motors to feed up to several hundred horses. Some types are based on  pistons and  cylinders , others use turbines. Many compressed air engines improve their performance by heating the incoming air or the engine itself. Pneumatic motors are popularized in portable equipment, although there are continuous attempts to expand their use in the transport industry.

Hydraulic Engine

A hydraulic motor is one that derives its power from a pressurized fluid. This type of motor can be used to move heavy loads or produce movement.

The designs of hydraulic motors are similar to those of hydraulic pumps. Some structural differences are associated with the reverse power flow through the hydraulic machine that operates in the hydraulic motor mode. Unlike hydraulic pumps, in the hydraulic motor, the working fluid is supplied to the input under  pressure , and the torque is eliminated from the shaft at the output.


Published: November 30, 2018
Last review: November 30, 2018