Steam machine

Alternative engine

Alternative engine

The reciprocating engine uses the reciprocating motion of one or more pistons to convert the pressure into a working fluid. Generally this work is in the form of rotation movement, that is, we obtain mechanical energy. In the opposite direction we find ourselves with the rotating machines in which the movement of the parts of the machine is already rotating like the turbines or the Wankel engine.

The reciprocating engine is also known as a piston engine. The most common alternative engines are internal combustion engines. These thermal engines are widely used in motor vehicles.

The combustion engines are classified in two ways:

  • The gasoline engine. It is also known as the spark ignition engine, otto engine or explosion engine. In this case, the spark plug starts combustion of fuel.
  • The diesel engine. It is also known as a compression ignition engine. In the diesel engine the air inside the cylinder is compressed, when compressed it is heated allowing to ignite the fuel.

Despite the importance of endothermic engines, there are other types of alternative engines:

Classification of the alternative engine

Alternative engines can be classified in many different ways. The main forms of classification are the following:

  • According to the arrangement of the cylinders in the engine
  • According to the displacement
  • According to the compression ratio
  • According to the diameter and stroke ratio
  • According to the number of movements of each cycle

Terminology of alternative engines

Alternative motor piston

Not all alternative engines correspond to the scheme described, but the essential parts and their operation are similar.

Below we attach a terminology used universally in the field of internal combustion engines or endothermic engines. This terminology is used to indicate some dimensions and fundamental values of this type of motor.

Top dead center (P.M.S.) Position of the piston closest to the cylinder head. Bottom Dead Center (P.M.I.). Piston position furthest from the cylinder head. Lower Dead Center (P.M.I.) Position of the piston furthest from the cylinder head.Diameter (in English: Bore) .Inner diameter of the cylinder. Expressed generally in millimeters (mm). Carrera (in English: Stroke). Understand the distance between P.M.S. and P.M.I., is equal, except for rare exceptions, to twice the radius of the crank shaft crankshaft. It is usually expressed in mm. Total volume of the cylinder (V1). It is the space between the cylinder head and the piston when it is in the P.M.I. It is usually expressed in cm3Volume of the combustion chamber (V2) .It is included between the cylinder head and the piston when it is in the P.M.S. It is usually expressed in cm3 Volume dislodged by the piston or displacement (V1 - V2). It is the generator by the piston in its alternative movement from the P.M.S. up to P.M.I: It is usually expressed in cm3. Volumetric compression ratio (


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  • ).) This is understood to be that between the total volume of the cylinder V1 and the volume of the combustion chamber V2. In general, for short, it is simply called compression ratio:
    ro equals volume 1 match by volume 2

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    Last review: December 13, 2016