Fuel Injection Systems Part 2

[jcge]

Hi Roger

Also interesting is the associated injection nozzle, which differs from the others in that the path of the spring-loaded nozzle needle is limited by a soft ring made of synthetic rubber. The interaction of rubber disc and spring means that a very good atomization of the fuel at the nozzle opening is achieved at large and small flow rates, regardless of the prevailing injection pressure.
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I can’t yet work out exactly what the rubber disc/ring in the injector does.

Roger - my guess is that the needle is limited in its lift ("path" above) under varying pressure and flow rate, much akin to the "lift stop" of the cutaway poppet nozzle of your post #46 above
Regards
John

[vtsteam]

I don't know anything about fuel injectors, other than what's in the name, but I am reading this Roger, and greatly enjoyed your 2-stroke diesel thread.    Took me a few days to read through it all, but definitely worth it!   

[Roger B]

Thank you  I have had a lot of fun with all this development stuff      Sometimes I feel a bit like the odd kid playing by himself in the corner so it is good to know others are enjoying it as well.

[Don1966]

Roger I admire your persistence!


 
Don

[Roger B]

Thank you Don 

Following some discussions I have decided to try and make a needle type injector for the four stroke diesel. This requires moving the fuel inlet a long way up the body to clear the head with some complicated deep drilling and silver soldering. I decided to try a few of the difficult stages first. The body will require a 20mm deep 1mm diameter hole which will then have to be plugged. The first 6mm depth was drilled 1.2mm to allow the silver solder to flow round the plug. The rest drilled 1mm with small pecks and frequent cleaning of the drill. That worked  I then started to drill the 1mm crosshole that will feed the needle. This can't be finished until the main bore is drilled otherwise it may deflect the bore. Next I turned a 1mm mild steel plug from some 5mm black bar, the smallest I had. This was supported on a piece of 1mm piano wire in the crosshole (I hoped the silver solder wouldn't wet the piano wire if it got that far) and silver soldered in place.

[Admiral_dk]

OK - so now you take us on the next leg of the Journey 

If not to the destination - then at least closer to it 

Best wishes and a Happy New Year 

Per

[vtsteam]

That's some pretty fine turning! 

[jcge]

Nice work getting a 1mm drill down 20mm Roger !!

[steamer]

 


Getting it done with what you got!   Love it!

Dave

[Kim]

That's some amazingly fine (in both senses of the word) work there, Roger! 

Kim

[Roger B]

Thank you all for your interest     

I know that the Proxxon machines don't tend to get good comments but 4800 rpm for drilling the deep 1mm holes and 2800 rpm for turning the 1mm plug are useful ( I could have  swapped the belt pulleys and gone to 4000 or 5000 rpm for the final cuts but it didn't seem necessary).

The next steps were to drill and tap the ends of the body. The bore was made as before, drilled 1.3mm and then reamed 1.45mm. It appears that the silver solder flowed down the plug.

The next step was to tap the first section of the cross bore M1.4 and screw a grub screw 2mm deep. The silver soldering didn't seem to flow well but hopefully it will hold the plug in place.

[Roger B]

The grub screw was filed flat and the end of the body was turned down to 8mm. The plug seemed to stay in place   

The next piece was the fuel inlet which will have to be set a 45° to clear the head studs and be drilled through to the passage in the body. The 1mm bore was only partially drilled to align the final hole through.

[Roger B]

The fuel inlet mating face was milled 45° and a 1mm hole for a locating pin was drilled. This hole was then spotted through to the body and the rest of the 1mm plug was used to hold the parts in place for silver soldering. With the inlet in place I then continued drilling the 1mm bore until it broke through into the 1mm bore in the body. Luckily the drill didn't break and the passages are well enough aligned that I can blow though from the inlet to the bore for the needle 

[steamer]

Nice fabrication job on that Roger.   I particularly like  the most elegant vise clamp straps.   Tastefully done!

I have found that small diameters don't need to have uber high rpm but they do need feed control     That said, the Proxxons seem to be performing well!

Dave

[RReid]

Always a pleasure to watch you work, Roger.