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Multiple Point Ion Current Diagnostics in an HCCI Engine

In English

Författare

  • Andreas Vressner
  • Petter Strandh
  • Anders Hultqvist
  • Per Tunestål
  • Bengt Johansson

Summary, in English

Interest in ion current sensing for HCCI combustion arises when a feedback signal from some sort of combustion sensor is needed in order to determine the state of the combustion process. A previous study has revealed that ion current sensors in the form of spark plugs can be used instead of expensive piezoelectric transducers for HCCI combustion sensing. Sufficiently high ion current levels were achieved when using relatively rich mixtures diluted with EGR. The study also shows that it is not the actual dilution per se but the actual air/fuel equivalence ratio which is important for the signal level. Conclusions were made that it is possible to obtain information on combustion timing and oscillating wave phenomena from the measurements. However, the study showed that the ion current is local compared to the pressure which is global in the combustion chamber. This observation triggered the

present study where the aim is to investigate the ion current at different locations in the combustion chamber. The ion current was measured simultaneously at seven locations in the combustion chamber. In order to achieve this, 6 spark plugs were fitted circumferentially in a spacer placed between the cylinder block and the head. The seventh spark plug was placed in the cylinder head. Individual DC sources of 85 volts were applied across the spark plug gaps. The present study indicates that the combustion timing seems to be dependent on the wall temperature at the different spark plug locations. The largest difference in timing between different locations in the combustion chamber was 2 CAD. The ion current amplitude varies with different spark plug locations up to 1.5 μA. The signal strength increases with decreasing air/fuel ratio and is also affected by dilution.

Publiceringsår

2004

Språk

Engelska

Sidor

544-550

Publikation/Tidskrift/Serie

SAE Transactions, Journal of Engines

Volym

113

Issue

3

Dokumenttyp

Artikel i tidskrift

Förlag

Society of Automotive Engineers

Ämne

  • Energy Engineering

Nyckelord

  • HCCI
  • Multiple locations
  • Ion Current
  • Engine

Status

Published

Projekt

  • Competence Centre for Combustion Processes

ISBN/ISSN/Övrigt

  • ISSN: 0096-736X