Twin injector system?

[richard vandervoort]

>With all this talk of using twin injectors etc. can anyone tell me the
reason 
>why injectors don't work well with short pulses? I can think of two possible 
>reasons:

Injectors are on off valves(also called bang bang 
valves) and are only designed to work at some mimimum 
on time.  Anything less than the min on time does not 
gaurantee the valve will open fully.  The electromagnet 
in a valve is just an inducter and it takes a while for 
the magnetic field to build and collapse. Remember an 
inducter resist changes in current.  When the magnetic 
field is at its peak the forces to move the plunger are 
relatively larger than the frictional forces and the 
pressure forces.  Several variable forces are involved 
in the plunger movement including; the pressure 
differential between the fuel and the intake pressure, 
stick slip friction (varies randomly) between the core 
and the valve body, temperature induced resistance 
changes, contamination induced friction, etc.  When a 
valve is turned on for less than the min on time the 
magnetic field does not build fully and the valves may 
open partually or not at all therefore if you are 
trying to use a partual opening for low flow there will 
be large fluctuations in the fuel flow.

end



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