Author Topic: Fuel injection systems  (Read 54975 times)

Offline Roger B

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Re: Fuel injection systems
« Reply #15 on: May 06, 2015, 12:48:10 PM »
And a little bit more. I found the article your drawing came from along with a translation on the RC groups forum:

http://www.rcgroups.com/forums/showthread.php?t=1054975&page=148

Thank you to JMP_blackfoot  :ThumbsUp:  :ThumbsUp:
Best regards

Roger

Offline Ian S C

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Re: Fuel injection systems
« Reply #16 on: May 06, 2015, 01:48:42 PM »
Twenty or so years ago i made a new injector piston for a Lanz Bulldog, can't remember the actual size, but near an inch diameter, the stroke is only a few thou. Other than the Lanz, the only fuel injection system I'v had anything to do with is that used by Continental on their aircraft engines,ie., the IO 470 etc. this system is a constant flow directed directly behind the intake valve, probably not the most economical method, but it's simple, and it works, and at a low pressure.
Oops, forgot there is also the Ruston Hornsby HR 6 at the museum.
Ian S C
« Last Edit: June 25, 2015, 02:50:24 PM by Ian S C »

Offline Graham Meek

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Re: Fuel injection systems
« Reply #17 on: May 06, 2015, 04:16:18 PM »
Hi Roger,

Thank you for finding out so much information on this engine, as well as the translation. I honestly did not expect to find any more information, given the date I am surprised the information has survived at all, especially as this developement was going on before and during WWII.

My best regards
Gray,

Offline Roger B

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Re: Fuel injection systems
« Reply #18 on: May 08, 2015, 02:24:36 PM »
Hi Gray,

The search required some lateral thinking as well as using German  ::)

The stated injection pressure seems very high, especially as the article suggests that an open nozzle was used. The fuel metering looks to be using the inlet valve as a spill valve (like in Lohring's picture) but part of the mechanism is not illustrated. It's always encouraging to know that someone has made it work before.

I also have a copy of Maschinen in Modelbau in the attic in England that has some details of a 7cc true diesel based on a Deutz horizontal prototype. I must dig that out next time I go back.
« Last Edit: May 12, 2015, 02:43:32 PM by Roger B »
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #19 on: May 09, 2015, 10:25:59 AM »
A few more tries at making bits. I made a new bracket for the grinder. Its only two bits from the offcuts drawer with a few holes but I managed to get both wrong the first time  :facepalm:

I then tried to improve the finish from the grinding operation with the following variables: Lathe at 2000rpm or 250rpm, grinder at 5000rpm or 25000rpm, aluminium oxide or silicon carbide grinding wheel, grinding with or against the workpiece direction.

None of the results were very good, but the best so far was both at low speed, aluminium oxide wheel and grinding with the workpiece. I need to get some sort of microscope to really see what is going on  ::)

Next I wanted to make some filing/polishing guides for the D bit. They were to be 8mm silver steel with a 1.5mm hole down the middle, a flat milled on the end to just over half diameter and hardened. On the first attempts the drill wandered way off the centre line  :headscratch: I then tried a brand new, hopefully good quality, drill which seemed to improve things. Yet more to learn  :headscratch:
Best regards

Roger

Offline cfellows

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Re: Fuel injection systems
« Reply #20 on: May 09, 2015, 04:13:37 PM »
Don't know if you are familiar with Find Hansen's engines, but he has had a fair degree of success with model injected engines.  Here is a link to his youtube channel...

https://www.youtube.com/channel/UCxv370lnEXq7MLmLuXMqklA

and a link to his website...

http://www.findsminimodelhotbulbengines.dk/

Here's some further links to his website that show pictures of his injectors and injector pumps...

http://www.findsminimodelhotbulbengines.dk/Side9.html

http://www.findsminimodelhotbulbengines.dk/Side1.html

He doesn't offer any drawings or plans for his work but he did tell me that a possible method for making the injector pump was to fill the pump cylinder with melted solder then insert the plunger, coated with oil.  You can see pictures of his pumps on his website.  His website makes tantalizing reading and is worth exploring thoroughly.

Chuck
So many projects, so little time...

Offline Roger B

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Re: Fuel injection systems
« Reply #21 on: May 09, 2015, 05:07:17 PM »
Thank you Chuck  :ThumbsUp: Yes I do know his website, and he doesn't give many details. That's a rather interesting way of making a very close fitting cylinder  ::)  :headscratch: it deserves some thought  :wine1:
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #22 on: May 11, 2015, 08:13:22 PM »
Next steps on the D bit guides.
I mounted both in the milling vice and milled flats down to almost half thickness. The silver steel was 7.98mm diameter so the one for filling was taken down to 4.10mm and the one for polishing to 4.03 so that the flat on the D bit will not quite reach the centre.
Whilst still in the vice both were drilled and tapped for an M2 grubscrew. I don't like doing hot work at the end of a session so I will harden them tomorrow.

I don't know if I am taking this too far  ::) , but it seems to me that the quality of the finish from the D bit, especially on the cone, will depend on the finish of the cutting edges. The literature generally says 'file to exactly half diameter' but again it seems to me better to be slightly above half than below  :headscratch:
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #23 on: May 12, 2015, 07:15:35 PM »
I hardened and tried my D bit guides. The results look much better than my free hand efforts, but I need to do some more work on grinding the tips   ::)

I also received some 0.01 mm step reamers and pin gauges ready for my experiments on making precision bores. I am also going to order the appropriate needle laps from Acrolaps.

Looking at the pin gauges and their cost (~12 CHF/EUR/USD or 7) they are much better finished than anything I could achieve with my current machines and may be a useful/sensible source of precision pump plungers  :headscratch:
Best regards

Roger

Offline Frank Boyle

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Re: Fuel injection systems
« Reply #24 on: June 05, 2015, 10:00:28 PM »
Hi.   Rodger
I am trying to make an injector in 3" scale ,if succesful will continue with the hot bulb hornsby engine.I have the full plans for the injector and the fuel pump and have scaled these down to construct the injector .I would be willing to send a copy of these to you they may help.
Regards Frank

Offline Roger B

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Re: Fuel injection systems
« Reply #25 on: June 06, 2015, 07:40:39 AM »
Hello Frank,

That would be very kind of you  :) All information is helpful  :ThumbsUp:  :ThumbsUp:
Best regards

Roger

Offline Ian S C

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Re: Fuel injection systems
« Reply #26 on: June 06, 2015, 02:46:51 PM »
I can hardly imagine making a working nozzle, I'v got 4 nozzles from a Continental IO-470 engine (some where), these ones are not direct injection, but inject petrol into the intake manifold, just behind the inlet valve, so they work at low pressure.  They are about 1.5" long.  The only other one I'v had anything to do with would not be too hard to scale, it's on a Ruston Hornsby 6 HR, and is about 6" long, my nephew, a diesel mechanic, over hauled it for me, he'd never seen anything like.
Ian S C

Offline petertha

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Re: Fuel injection systems
« Reply #27 on: June 23, 2015, 04:31:57 AM »
I'm fascinated by your micro-drilling Roger. Very interesting tooling arrangements.

Would these 35K dental type drills provide appropriate rpm for those teeny drills & reamers? The electrics like pic tend to go for $100-150-ish with dedicated speed control boxes (ebay). I'm told by my dentist friend the pro versions have pretty high quality ceramic bearings & low run-out, but he might be referring to pneumatic drive which I thought he said was higher rpm yet. No idea if that's what is contained in these units.

Offline Roger B

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Re: Fuel injection systems
« Reply #28 on: June 24, 2015, 08:34:44 PM »
Peter (I guess),

I do have a Proxxon hand drill which will reach 25,000 rpm and a Proxxon bench drill that will do 8,000 rpm. The problem is drilling in the lathe which has a top speed of 2,000 rpm.

I decided to make some experiments on an injection pump. The first version will have an inlet port in the barrel like a full sized one. If this is not successful I will make one with an inlet valve. The piston will be 2mm Silver Steel (drill rod) hardened and polished/lapped. The body is from 10mm square hot rolled mild steel. The bore was drilled 1.8mm and reamed 1.95mm. My 1.98mm pin gauge would not enter so there is hope. The delivery valve will screw into the recess at the square end. the other end is turned down to 6mm for a return spring.
Best regards

Roger

Offline fumopuc

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Re: Fuel injection systems
« Reply #29 on: June 25, 2015, 04:10:45 AM »
Hi Roger, I am following along.
Kind Regards
Achim