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Getting an electronic fuel injector to only open partially
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joeqsmith:
I wonder how your other valve worked out?  I figured for sure you would have got a kick out of the old man's history on it.  Hard to argue with his success.

https://www.eevblog.com/forum/chat/200hz-air-valve/

At one point, we had a quartz window and laser that we could use to take photos of the patterns.  We did whole studies on how the orifice effected it.    That's been decades ago and before the piezo injectors.  Anything I have worked on was always an on/off type valve.   We did work on a multi-pulse system.  Basically firing the injectors several times for one combustion cycle.   Think of integrating the area under the curve.  We could then change the shape of it.  It also allowed us to trim individual cylinder.   Seems like a whole different life time......
ELS122:

--- Quote from: Miyuki on June 04, 2023, 06:26:21 pm ---Most fuel injectors are not spraying from the needle but from an array of tiny precisely machined orifices in a plate on its tip
Opening the valve just partially will decrease the spray pressure, so it will just make big droplets
Such ancient injector construction was used on throttle body injector with very low pressure spraying at the throttle plate and just evaporating the fuel in the long intake manifold

--- End quote ---


That's the fucking idea.
It's amazing how everyone here is unable to understand the question I asked.
bdunham7:

--- Quote from: ELS122 on June 05, 2023, 02:48:07 am ---That's the fucking idea.
It's amazing how everyone here is unable to understand the question I asked.

--- End quote ---

Perhaps you don't understand the question you asked since you seem to be stating it backwards.


--- Quote from: ELS122 on June 04, 2023, 05:13:44 am ---Well a big difference, smaller outlet orifice = higher velocity = more breakup, atomization.

--- End quote ---
TERRA Operative:
Injectors are optimised to spray correctly at a certain fuel pressure range.
Altering the pintle position when open will affect the pressure of the fuel exiting the valve portion of the injector before it hits the director plate that actually determines spray pattern and droplet size. Less open pintle = less flow = less pressure at the plate and sub-optimal spray pattern.
Also, the injectors in a manifold injection system don't actually spray directly into the open combustion chamber anyway, they spray onto the back of the intake valves to help keep them cool and to evaporate the fuel for better atomization.

My thinking to increase atomization would be to increase fuel pressure then decrease the injector on-time to compensate for correct air/fuel ratios.

But before diving into injector droplet size, I'd be doing more 'tried and true' methods of increasing efficiency and power, like forced induction, porting and polishing the intake system, flow matching the intake and exhaust ports, adjusting intake and exhaust runner lengths to optimise the powerband for the application at hand and designing the exhaust system to scavenge at the same RPM range.

Then use an aftermarket ECU to tune the car to a better/leaner tune on a dyno instead of relying on an overly conservative OEM tune.
Miyuki:

--- Quote from: joeqsmith on June 04, 2023, 07:57:43 pm ---I wonder how your other valve worked out?  I figured for sure you would have got a kick out of the old man's history on it.  Hard to argue with his success.

https://www.eevblog.com/forum/chat/200hz-air-valve/

At one point, we had a quartz window and laser that we could use to take photos of the patterns.  We did whole studies on how the orifice effected it.    That's been decades ago and before the piezo injectors.  Anything I have worked on was always an on/off type valve.   We did work on a multi-pulse system.  Basically firing the injectors several times for one combustion cycle.   Think of integrating the area under the curve.  We could then change the shape of it.  It also allowed us to trim individual cylinder.   Seems like a whole different life time......

--- End quote ---
Thar must be crazy work to do. I know how annoying it can be to just adjust the injection for different types of injectors with different on and off response times.
And now with modern piezo-style injectors, multi-injection is something all engines do.


--- Quote from: ELS122 on June 05, 2023, 02:48:07 am ---That's the fucking idea.
It's amazing how everyone here is unable to understand the question I asked.

--- End quote ---
Big droplets will always have worse efficiency
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