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Internal Combustion Engines
Published in Don M. Pirro, Martin Webster, Ekkehard Daschner, Lubrication Fundamentals, 2017
Don M. Pirro, Martin Webster, Ekkehard Daschner
Crosshead-type engines are also built with double-acting pistons, or with two pistons acting in opposite directions in the same cylinder—this configuration is called an opposed piston engine. One of the chief disadvantages of crosshead construction is that it results in an engine that has a greater overall height than a trunk piston engine of the same horsepower. However, most engines with bores larger than 600 mm (24 in) are of the crosshead type.
Impact of ethanol, methyl tert-butyl ether and a gasoline–ethanol blend on the performance characteristics and hydrocarbon emissions of an opposed-piston engine
Published in Biofuels, 2020
The opposed-piston engine has a simpler structure than that of conventional reciprocating engines. Because there are two pistons per cylinder, the opposed-piston engine does not require cylinder blocks, which are the main cause of heat losses in conventional reciprocating engines [1]. In the opposed-piston engine, when the piston reaches bottom dead center, air is discharged from the intake ports of the cylinder and fresh air is taken from the ports under the cylinder. When the pistons are close to each other, the fuel is injected into the compressed air or the air–fuel mixture is ignited via spark plug. The upper and lower pistons each rotate on a separate crankshaft. These two crankshafts are fitted with gears to transmit power to the output shaft. In some opposed engine types, power transmission is carried out via a single crankshaft [1]. The opposed-piston engine does not have a camshaft, rocker arm, valve or valve spring. This reduces engine production costs and gives the engine a simple structure. In addition, opposed-piston engines have higher thermal efficiency, a more compact design, much lower fuel consumption, lower emissions, and lower engine weight than conventional reciprocating engines [2–6].