Author Topic: Fuel Injection Systems Part 2  (Read 21614 times)

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #90 on: January 21, 2023, 03:44:54 PM »
Thank you  :)   A sharp insert, high speed (2800rpm) and shallow cuts (0.05mm).

I assembled it and tested it without the needle spring. The 0.35mm hole gave a nice jet but no atomisation.

<a href="https://www.youtube.com/watch?v=JAZUb5ams2E" target="_blank">http://www.youtube.com/watch?v=JAZUb5ams2E</a>

When I applied pressure to the needle there was a significant leak from the nozzle fixing thread. I decide to reduce the size of the anulus on the nozzle to increase the clamping pressure and to recut the seating in the body. This worked but I then had a leak from the fuel inlet union. After some inspection and thought I realised I had cut the seat 90° not 60°   :toilet_claw:   This was easily fixed.

The final step was to cut the needle to length and assemble it with the spring and spring cap from an existing injector.
The spray pattern is somewhat offset, probably due to a lack of concentricity between the nozzle and the needle. The atomisation looks good and the opening pressure is adjustable in the correct range.

<a href="https://www.youtube.com/watch?v=hv5i8zO_tx8" target="_blank">http://www.youtube.com/watch?v=hv5i8zO_tx8</a>

<a href="https://www.youtube.com/watch?v=pQytbUvBtBE" target="_blank">http://www.youtube.com/watch?v=pQytbUvBtBE</a>

Finally everything that had been in contact with the diamond paste went in the ultrasonic bath
Best regards

Roger

Offline Kim

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Re: Fuel Injection Systems Part 2
« Reply #91 on: January 21, 2023, 05:58:17 PM »
Incredibly small and meticulous work, Roger!  I find it just amazing!  :popcorn:

Kim

Offline jcge

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Re: Fuel Injection Systems Part 2
« Reply #92 on: January 21, 2023, 10:24:17 PM »
Roger - that is looking great !
Whilst the spray pattern may not be as concentric as you'd like, there appears to be good atomisation of the fuel stream.
And the video of the 0.35mm nozzle stream looks viable for non diesel manifold injection as well
Bravo !
Regards
John

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #93 on: February 12, 2023, 12:30:32 PM »
Thank you both  :)

I fitted it to the engine for a trial. It runs but there is still a lot of un atomised fuel coming out of the exhaust. You can also see some leakage past the needle coming out of the centre of the spring adjuster.

<a href="https://www.youtube.com/watch?v=NncOlT-Vfxw" target="_blank">http://www.youtube.com/watch?v=NncOlT-Vfxw</a>

This design has some problems for manufacture. The blind passages are the main one, followed by the sealing and alignment surface between the nozzle and the nut. I have been playing around with various designs and have come up with a version based on full size designs. The fuel passages are open at the end and the sealing faces are exposed and can be easily lapped, rather then one being buried. The nozzle and the end of the body will be 7mm diameter to keep the parts aligned and the clamping thread will be M8x1.
Best regards

Roger

Online steamer

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Re: Fuel Injection Systems Part 2
« Reply #94 on: February 12, 2023, 01:24:50 PM »
That is sweet Roger.    I admire the effort here.   Very few have accomplished what you have done and are doing!    Well done sir! :NotWorthy:
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline RReid

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Re: Fuel Injection Systems Part 2
« Reply #95 on: February 12, 2023, 03:11:10 PM »
Looks like a good plan. If development was easy...  :ThumbsUp: :wine1:
Regards,
Ron

Offline vtsteam

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Re: Fuel Injection Systems Part 2
« Reply #96 on: February 12, 2023, 03:43:17 PM »
Great to see it running, Roger, still following. Looking forward to your latest design, and hoping it will do exactly what you want it to!  :popcorn: :popcorn: :cheers:
Steve

Offline Admiral_dk

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Re: Fuel Injection Systems Part 2
« Reply #97 on: February 12, 2023, 05:30:28 PM »
Sound like a happy Runner  :ThumbsUp: and good to see it run again  :cheers:

I like the latest draft - but I have one small sugestion, to help with leakage .... (just thinking out loud).
Make the Blue Collar slightly longer so it goes up over the solid above the thread + remove the top end of the thread with a grooving tool and put a small O-Ring there.
Perhaps a bit premature - as you haven't disclosed where the leak is yet  :embarassed:

Per        :cheers:            :popcorn:

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #98 on: February 19, 2023, 05:39:13 PM »
Thank you all for your interest and support  :)

Per, I have attached a similar drawing of the current injector. The centring and sealing of the nozzle are via an M5 x 0.5 thread  and a narrow ring as in my delivery valves. The new version moves the centring to a closely machined 7mm diameter on the nozzle and the body. The sealing is then by a 1mm wide ring between the nozzle and the body.

Looking at this design there was limited space for M8 x 1 threads so I purchased an M8 x 0.5 set.

The nozzle is made from 8mm brass rod. I started in the Hobbymat as the headstock bore of the Proxxon is only 7mm. I have kept the 4 jaw SC chuck on for making the body. The flange was turned to 6.99mm and the nozzle bore was completed much as before. I decided to go for a 0.2mm orifice this time.
Best regards

Roger

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #99 on: February 19, 2023, 05:41:04 PM »
The final stage was to cut the fuel recess with a 5mm end mill. There was a little chatter at the start but this didn't affect anything important.
Best regards

Roger

Offline Admiral_dk

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Re: Fuel Injection Systems Part 2
« Reply #100 on: February 19, 2023, 06:48:04 PM »
Wauw - great finish down in this small size  :praise2:

So this absolute latest, looks like you fairly easy can change the Nozzle - if you want to test different Orifice versions ...?

Per

Offline Kim

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Re: Fuel Injection Systems Part 2
« Reply #101 on: February 19, 2023, 07:36:45 PM »
Very nice!  You make some REALLY tiny holes, Roger! No small feat there!  :popcorn:

Kim

Offline RReid

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Re: Fuel Injection Systems Part 2
« Reply #102 on: February 19, 2023, 08:41:08 PM »
OK, I like metric and I've happily worked in metric at times, but I don't think in metric. So 0.2/25.4 = 0.0078"! Wow. Not only is that a tiny drill to use, but I have to wonder just how they make those in the first place!
Regards,
Ron

Offline vtsteam

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Re: Fuel Injection Systems Part 2
« Reply #103 on: February 19, 2023, 09:42:13 PM »
I have a small book called "Making Tiny Drills" where it's done with a grinding wheel on a watchmaker's lathe. But not a twist drill! Amazing work Roger!  :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :cheers:
Steve

Offline jcge

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Re: Fuel Injection Systems Part 2
« Reply #104 on: February 19, 2023, 10:23:32 PM »
Roger - 0.2mm is a pretty small hole !! well done.
Does the nozzle hole, cleaned up with the D bit,  fit the shank of the drill to hold it concentric for drilling the final 0.2mm dia hole ? Or is there some other witchcraft going on ? Or did I just miss the explanation ?
Needless to say, I'm very impressed.
John

 

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