What should the control system design be? Whether controlling air and fuel mass flow rate separately or signal should come from lambda sensor to the ECU (Engine control unit) for control .
Please advise whether all the above control is required simultaneously?
That is the conundrum, right? You have a compression engine in which you cannot count on anything as deterministic as a spark from a spark plug, or a squirt of fuel from a fuel injector. Instead, you have to make it so that detonation occurs naturally, just by compressing the mixture, at exactly the right time (at or just barely before top dead center in the compression stroke).
Detonation is delayed if you admit more fuel for a given amount of air, and advanced if you admit less fuel, because fuel will tend to cool the cylinder. On the other hand, the amount of fuel and air admitted must also depend on the torque being requested by the driver. Then at higher RPM, detonation must occur a little bit sooner than at low RPM, to achieve maximum efficiency.
This suggests to me that air and fuel need to be controlled independently, and that the amount of each will depend on driver demands for torque, but also on ambient air temperature, air pressure, engine temperature, and engine RPM.
The answer here would be yes in my opinion ,first going to the basic part the air flow will be controlled by a throttle(under human control),the ECU could make a decision on how much fuel could be added before the mixture travels to the combustion chamber this would be decided by the target lambda value fed in the ECU ,in HCCI engines a lean mixture is preferred so the ECU gets a reading from the lambda sensor and controls the fuel flow such that it stays lean.
Hope this answers your question.
Cheers!
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