Q2. What are the key parameters to the ideal injection process?
Injection pressure, fuel quantity, injector opening and closing timings and other parameters are keys to the ideal injection process condition monitoring system.
Q3. What was the effect of the proposed adaptive scheme on the injector?
14To extract the injector operation impacts from the monitored airborne acoustic signals using the proposed adaptive scheme, the dominant harmonic components were removed using a high pass filter and the residual signal was used as an input to the proposed adaptive scheme.
Q4. What is the purpose of the second stage?
The second stage aims to reduce the broadband noise, for this the authors need a fast convergence algorithm such as a short Normalised Least Mean Square (NLMS).
Q5. Why is the improvement of diesel engines necessary?
Improvement of diesel engines performance necessities has arisen as a result of the increasing interest in environmental problems, and reduction of noise and pollutant emissions.
Q6. What is the effect of the injection on the engine?
Any decrease in the stiffness will change the injection time and therefore degrade the combustion process and the engine performance.
Q7. How long does it take to open the injector?
In the medium size, high speed diesel engines, the moving mass inside the injector is small in the order of 15 grams, and this mass takes a very short time, in the order of 1-3 milliseconds, from the fully open to fully closed position.
Q8. What is the importance of the proposed procedure in diagnosing injector related faults?
More importantly, SNR improvement allows various statistical methods to be successfully used in diagnosing injector related faults.
Q9. How was the air-borne acoustic signal measured?
The air-borne acoustic signals were measured using a high-bandwidth free-field condenser microphone, B&K model MK224, the sampling frequency was set to 80 kHz.
Q10. How much pressure was reduced by the injection pressure?
In this case the opening pressure of the healthy injector was 250 bars and by reducing the spring stiffness the injector opening pressure was reduced to 230 bars.
Q11. What is the common type of adaptive noise canceller?
Another scheme called Adaptive Self Tuning is depicted in Figure 3, this scheme in fact a degenerate form of the adaptive noise canceller in that its reference signal, instead of being derived separately, consists of a delayed version of the input signal [13].
Q12. What is the tap weight adaptation of LMS algorithm?
The tap weight adaptation of LMS algorithm can be written as )()()()1( nenxnwnw (3) Where )(nw is the coefficient vector at time ,n is the step size, )(ne is the adaptation error and )(nu is the input vector, respectively, at time n .
Q13. What type of engine was used for the test?
The experiments were performed with a four-stroke, four-cylinder, in-line OHV, direct injection, Ford FSD 425 type diesel engine.