Acro air storage method

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Acro air storage drawing.
Above: Side view
Below: Top view of

air reservoir on the left in the picture, injection nozzle on the right.

The Acro-air storage method is an injection method for diesel engines of Acro . It was developed by Franz Lang in the 1920s , and Bosch has held the patents for the Acro air storage process since 1925 (DRP 52 82 44/1926). It is counted as an indirect injection process because the fuel is injected into the combustion chamber, but not onto the piston crown, but in front of an auxiliary combustion chamber, the so-called air reservoir. Motors with acro air storage process run very smoothly and are easy to start even at low temperatures. Compared to direct injection, however, the possible power is reduced and fuel consumption is greatly increased. As a result, they were already considered technically obsolete in the 1970s. The method was only considered for smaller engines with medium loads, in which high fuel consumption can be tolerated. Acro air storage motors experienced a certain spread in American engine construction.

functionality

With the Acro air storage process, there is another combustion chamber, the so-called air storage, which is housed in the cylinder cover at an angle above the actual combustion chamber and is connected to the main combustion chamber. The fuel is injected in front of the air reservoir in such a way that part of the fuel enters the main combustion chamber and the other part enters the air reservoir. The fresh air flowing into the combustion chamber during the intake stroke is compressed in the air reservoir and pushed out of the air reservoir again during ignition; it is directed in the opposite direction to the fuel jet in order to improve the turbulence and thus the mixing of fuel and air through the violent gas movement. As with all engines with indirect fuel injection, the combustion chamber surface is larger compared to the engine with direct (direct) fuel injection, which results in greater heat transfer, which is further increased by the violent gas movements. This reduces the efficiency of the engine and thus increases fuel consumption. In addition, the combustion is only ended very late and the effective expansion ratio is reduced, as a result of which the output is reduced.

literature

  • Walter Pflaum and Klaus Mollenhauer: Heat transfer in the internal combustion engine . Springer, Vienna, 1977. ISBN 978-3-7091-8453-0 . P. 59 ff.
  • Harry R. Ricardo: The high-speed internal combustion engine . Translated by Heinrich Niermeyer. Springer, Berlin / Heidelberg, 1954. ISBN 978-3-662-11454-4 . P. 93 ff.
  • Robert Bosch GmbH (Ed.): Diesel engine management: systems and components . Springer, Wiesbaden, 2004. ISBN 9783528238735 . P. 17 ff.
  • Olaf von Fersen: A Century of Automotive Technology: Commercial Vehicles . Springer, Berlin / Heidelberg, 1987. ISBN 9783662011195 . P. 130

Individual evidence

  1. ↑ v. Heels: A Century of Automotive Technology: Commercial Vehicles . P. 130
  2. ↑ Bosch: Diesel engine management: systems and components . P. 17
  3. ^ ATZ, Automobiltechnische Zeitschrift, Volume 75. Franck, 1973. P. 118
  4. ↑ a b Pflaum, Mollenhauer: Heat transfer in the internal combustion engine , p. 61 ff.
  5. ↑ a b Ricardo: The high-speed internal combustion engine . P. 94