Lean engine

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A lean- burn engine (also known as a lean-burn engine ) is an internal combustion engine whose air / fuel mixture is kept in the lean range. Lean means that there is more combustion air than is required for the stoichiometric combustion of the fuel in the cylinder ( lambda > 1). The excess air leads to a decrease in the combustion temperature, which increases the efficiency . Depending on the degree of leanness, the raw nitrogen oxide emissions can be above or below the values ​​of a stoichiometrically operated engine. However, conversion in a three-way catalytic converter is not possible, which is a major disadvantage of this technology.

In the case of lean-burn engines, direct injection is sometimes used to store the fuel near the spark plug in a concentration that is still ignitable ( stratified charge ).

literature

  • Hans-Hermann Braess, Ulrich Seiffert: Vieweg manual automotive technology. 2nd edition, Friedrich Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig / Wiesbaden, 2001, ISBN 3-528-13114-4