Engine Management

The structure of the information, to follow, will be:

Timing - For whatever is being done with the motor, either ignition or fueling, it is necessary to know the current angle, and the angular velocity. This is obtained using the CAM and CRANK input signals.

Scheduling - Knowing location and velocity, it is possible to predict time to events.

                         The coils need to be charged and ignition has to occur at a specific time

                         The fuel injector solenoids need to open and close to supply the proper volume of fuel.

Calculation - Ignition and Fueling.

                         Ignition requires specific timing for angle of advancement, and start of dwell.

                         Fueling calculates the quantity of fuel and depends on mass air flow combined with target air fuel ratio.

Sensors - The calculated values depend on measured values during operation.  Using A/Ds and providing conversions.

                         Sensors provide measurements for pressure, temperature, throttle position and other values at different locations in the system.

Steady State vs Asynchronous behaviors - changes in load or demand, and making quick adjustments to improve performance. Math tricks and creative use of units.

Calibration - Providing adjustments to "tune" the operation and optimize behavior for whatever is required.

Monitoring - communication of operating parameters

Checking back to make sure I am covering things the way I said, and so far I haven't strayed too far. The only thing I skipped was the part about injectors. This is was because the only thing different about injectors is the schedule. There are different strategies with injectors, they are; throttle body injection (TBI), batch, staggered batch, sequential, and staged.

TBI is the simplest, and is quite similar to normal aspiration. Normal aspiration is when the fuel is drawn into the carburettor by the intake vacuum, and controlled by a needle valve. With throttle body injection, the injector shoots the fuel into the intake chamber.  With normal aspiration, the flow is continuous, with TBI, it is pulsed to control the volume of fuel, and with TBI it is pulsed four times per cam cycle. Batch is when the injectors are mounted along the intake manifold, closer to the cylinder intake, and usually an injector for each cylinder. Batch means all the injectors open at the same time, twice per cam cycle. Staggered fire, is the same as batch, except the injectors are divided into two groups, and each group fires together, twice per cam cycle, but out of phase so half then the other half then the first again, etc.

The last two are for performance systems, again with injectors close to the cylinder intake (or inside the cylinder). Sequential means the fuel is supplied during the intake fueling stroke of the cylinder and needs to be timed accordingly. Since it is sequential, each injector operates independently, and only fires once per cam cycle. Staged fueling is again, for high performance systems when the demand for fuel exceeds what can be supplied by a single injector. In these cases, a second bank of injectors is used to increase the volume. The timing follows the pattern of sequential injection.

Without getting into volume of fuel (yet), it is possible to see the scheduling of fuel injections becomes just another event pair to open and close the injectors, either individually or as a group. The timing can be associated again with an angle of event.  There is lots more to fueling, which will be covered, but I hope this provides how much of the work is already in place from the ignition timing operation.

Jack

Checking back to make sure I am covering things the way I said, and so far I haven't strayed too far. The only thing I skipped was the part about injectors. This is was because the only thing different about injectors is the schedule. There are different strategies with injectors, they are; throttle body injection (TBI), batch, staggered batch, sequential, and staged.

TBI is the simplest, and is quite similar to normal aspiration. Normal aspiration is when the fuel is drawn into the carburettor by the intake vacuum, and controlled by a needle valve. With throttle body injection, the injector shoots the fuel into the intake chamber.  With normal aspiration, the flow is continuous, with TBI, it is pulsed to control the volume of fuel, and with TBI it is pulsed four times per cam cycle. Batch is when the injectors are mounted along the intake manifold, closer to the cylinder intake, and usually an injector for each cylinder. Batch means all the injectors open at the same time, twice per cam cycle. Staggered fire, is the same as batch, except the injectors are divided into two groups, and each group fires together, twice per cam cycle, but out of phase so half then the other half then the first again, etc.

The last two are for performance systems, again with injectors close to the cylinder intake (or inside the cylinder). Sequential means the fuel is supplied during the intake fueling stroke of the cylinder and needs to be timed accordingly. Since it is sequential, each injector operates independently, and only fires once per cam cycle. Staged fueling is again, for high performance systems when the demand for fuel exceeds what can be supplied by a single injector. In these cases, a second bank of injectors is used to increase the volume. The timing follows the pattern of sequential injection.

Without getting into volume of fuel (yet), it is possible to see the scheduling of fuel injections becomes just another event pair to open and close the injectors, either individually or as a group. The timing can be associated again with an angle of event.  There is lots more to fueling, which will be covered, but I hope this provides how much of the work is already in place from the ignition timing operation.

Jack