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6 Application

ARIADNE Knock Control 13

6 Application

ARIADNE monitors up to 20 vibration sensors placed on the engine structure. Depending on

the configuration, one sensor is assigned to one or several cylinders. In comparison to normal

cycles, knocking combustion produces high frequency pressure oscillations which act as a

vibration source on the engine structure and make the knock sensor signal clearly higher for

certain frequencies. By using a configurable bandpass filter ARIADNE only monitors this

engine specific knock frequency suppressing all non knock-related usual engine vibrations.

ARIADNE also needs engine speed and phase to determine, for each cylinder individually,

the time window where knock combustion is susceptible to occur (usually, knock is measured

just after cylinder top dead centre , for example between TDC and TDC+50°crank) (↑ Figure

5 ARIADNE functional Overview).

Several measures can be taken to reduce knock:

 In case of light knocking, the first action is normally to reduce step by step the spark angle

(for example in steps of 0,5° crank). If knock combustion disappears the spark angle is

progressively increased back to its nominal value.

 If knock combustion is still present after the spark angle has been reduced to its minimum,

the engine has to be gradually derated to avoid potential damages: the load is reduced step

by step and increased back to its nominal value if knock disappears.

 If the 2 previously described actions have not allowed to reduce the knock level signifi-

cantly, a correction of the air-fuel ratio might be necessary.

 If the knock level detected increases up to the heavy knocking limit, indicating a very high

knock severity with potential fatal damages, the engine must be stopped.

ARIADNE is particularly adapted to following engine types:

 V- or inline gas engines

 Rated speed of 300 … 1800 rpm

 Rated load from 100 … 8000 kW

 Number of cylinders from 4 … 20

ARIADNE has been designed to suit all gas engine control system applications. In order to

give an idea of the range of possible applications, 2 usual configurations are described in the

following in some more details.

Heinzmann ARIADNE User Manual

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