knocking

knocking

      in an internal-combustion engine, sharp sounds caused by premature combustion of part of the compressed air-fuel mixture in the cylinder. In a properly functioning engine, the charge burns with the flame front progressing smoothly from the point of ignition across the combustion chamber. However, at high compression ratios (compression ratio), depending on the composition of the fuel, some of the charge may spontaneously ignite ahead of the flame front and burn in an uncontrolled manner, producing intense high-frequency pressure waves. These pressure waves force parts of the engine to vibrate, which produces an audible knock.

      Knocking can cause overheating of the spark-plug points, erosion of the combustion chamber surface, and rough, inefficient operation. It can be avoided by adjusting certain variables of engine design and operation, such as compression ratio and burning time; but the most common method is to burn gasoline of higher octane number.

* * *


Universalium. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • Knocking-in — is a process done to new cricket bats to compress the wood and allow them to be ready for use as most brand new cricket bats will crack or badly dent if used in competition immediately.The Knocking In ProcessAfter the application of a thin layer… …   Wikipedia

  • Knocking — may refer to:*Knocking, Austria, a city in Austria * Knocking , a documentary about Jehovah s WitnessesKnocking may also call to mind:*Engine knocking, or the sound accompanying automotive combustion malfunction*Port knocking, a covert method of… …   Wikipedia

  • Knocking — Knock ing, n. A beating; a rap; a series of raps. [1913 Webster] The . . . repeated knockings of the head upon the ground by the Chinese worshiper. H. Spencer. [1913 Webster] …   The Collaborative International Dictionary of English

  • Knocking — Knock Knock (n[o^]k), v. i. [imp. & p. p. {Knocked} (n[o^]kt); p. pr. & vb. n. {Knocking}.] [OE. knoken, AS. cnocian, cnucian; prob. of imitative origin; cf. Sw. knacka. Cf. {Knack}.] 1. To drive or be driven against something; to strike against… …   The Collaborative International Dictionary of English

  • Knocking — Pareja de testigos de Jehová predicando en una puerta. Knocking (llamando a la puerta en inglés) es un documental producido en los EEUU en el año 2006. Se trata de un análisis de como los Testigos de Jehová se han enfrentado a su labor,… …   Wikipedia Español

  • knocking — noun the sound of knocking (as on a door or in an engine or bearing) (Freq. 1) the knocking grew louder • Syn: ↑knock • Derivationally related forms: ↑knock, ↑knock (for: ↑knock) …   Useful english dictionary

  • Knocking — Wappen Karte …   Deutsch Wikipedia

  • knocking — detonacija statusas T sritis chemija apibrėžtis Savaiminis oro ir degalų mišinio užsidegimas karbiuratoriniame vidaus degimo variklyje. atitikmenys: angl. knocking rus. детонация …   Chemijos terminų aiškinamasis žodynas

  • knocking —  Criticism, knocking shop Brothel …   A concise dictionary of English slang

  • Knocking (film) — Knocking is a 2006 documentary film directed by Joel Engardio [Miller, Lisa, Newsweek, May 28, 2007, Belief Watch: Witness, http://www.newsweek.com/id/34541] and Tom Shepard that focuses on the civil liberties fought for by Jehovah s Witnesses.… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”