Solenoid diesel injection pumps

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I just finished moving and am months away from getting my shop to be functional. That being said I am picking away at the issues I will need to solve to build a small two stroke diesel.

Currently my thoughts are a 1" bore with a 4" stroke.

My initial plan is to build a single cylinder proof of concept unit and supply it with shop air at 15psi.

From there I want to build a 5 cylinder version that will use a bought roots blower as the air supply.


I want to start with the fuel system and perfect that before building the engine.

To that end, I plan on designing a small injector that will use minimal lapped parts and a separate fuel pump to generate the flow to run the injector. They will be connected with some sort of schedual 80 small bore stainless pipe.

For the fuel pump I am thinking that the easiest solution is to do away with mechanically driven pumps and to use a series of solenoids with a common plunger. One coil would extend a 1mm diameter plunger into a true plunger pump, the other coil would take the place of a return spring and withdraw the plunger.

With off the shelf solenoids, a 1mm plunger pump should easily generate 10,000psi.

The stroke length and timing would be arduino controlled. The dual coil solenoid pump would only need a single double pole relay to control it.

I have a few quadrat sensors somewhere that could be used to adjust timing, injection duration and injection volume.


The plunger pump will have a positive pressure feed pump, which will also allow for a fuel filter to be used.

Can anyone see any foreseeable problems with this set up?
 
Sounds like a very interesting build in my opinion.

Some of my thoughts.
You may need a crosshead with that big stroke to bore ratio.

At 1000rpm and a injection cycle of 40 degrees you will have about 6.6 milliseconds of injection time.
40 degrees may be a bit long especially for low rpm?

So you need enough speed in your solenoids.
And at 10000 psi you will need about 12 pounds of force for a 1mm plunger.
I wonder if a servo motor could drive a injector pump?

Your 50cc cylinder will also consume 100 liter of atmospheric shop air a minute at 1000 rpm and 2 to 1 pressure ratio (15psi).

You could also use your solenoid system to operate the injector as a common rail with a constant fuel pressure. if it will give you any advantage I don't know.

If you succeed I would like yo try it for myself, model diesel is something I have been wanting to do some time in the future and this could simplify the injection if it works well.

Best of luck to you!
 

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