Abstract
GIE MOTUS (CRMT + METRAVIB R.D.S.) has developed for the account of PSA a new Diesel engine combustion noise measurement apparatus called 'CombustioMétre'.
The key of its principle consists in analysing, for each engine cycle and for each cylinder, the signal of accelerometer mounted onto the engine, either on the vehicle or in an engine test cell.
- In a first step, this signal processing provides combustion noise in 'physical units'.
- If necessary, the combustion noise, thus achieved in terms of acoustic pressure is converted into a subjective noise assessment, thanks to a
'learning session' with simultaneous CombustioMétre recordings and quotations established by a panel of experts. These data are used to determine, for each kind of engine, the values of the parameters to be used for converting 'physical noise' into 'subjective quotation'.
This new tool proves to be a very efficient help for mapping common-rail injection in order to compromise with emissions regulations, fuel economy and acoustic quality of the engine.
Besides this 'primary function' of noise assessment, CombustioMétre also proves to be a very useful tool for detecting, in a non-intrusive way, engine problems such as an unstable combustion, abnormal combustion on one cylinder, etc.