Author Topic: Fuel Injection Systems Part 2  (Read 21001 times)

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #120 on: March 25, 2023, 08:23:06 AM »
Continuing with the needle injector. Clearance slots for the clamping nuts were cut with an 8 mm ball end mill. This was easier than on the mark 1 as the clamping plate can be unscrewed. The bore was then lapped to a good fit on a 1.48mm pin gauge. The needle was then started from a piece of 1.5 mm silver steel. The tip was turned to 60°. Is a 60° cone in a 90° seating sensible? I am hoping for a very narrow seat so time will tell. The end of the needle was then turned down to 1mm to allow fuel flow into the nozzle. The tip and the first part of the shank were hardened and then lapped to 1.48 mm to be a close fit in the body. The needle tip and the nozzle seating were then lapped together. After that it all went in the ultrasonic bath to remove the residue of the diamond paste.
Best regards

Roger

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #121 on: March 25, 2023, 11:32:17 AM »
The needle was then parted off from the rest of the rod, which makes further lapping of the seat more difficult. I would need to make some sort of extension holder.

When the injector was assembled for the first trials the needle showed a tendency to stick open. Careful investigation showed the end of the needle was around 5 microns oversize. This was lapped down to size which seems to have resolved the problem  :)

I had also received the new springs for the mushroom/poppet style injectors which should allow the needles to seat freely. Time for some more Rorschach inkblot tests.

This is the new injector with the spring holding the needle shut, looks possible.

<a href="https://www.youtube.com/watch?v=DzFSroSf4nc" target="_blank">http://www.youtube.com/watch?v=DzFSroSf4nc</a>

This is with the spring removed and just the 0.2mm hole. Not enough atomisation.

<a href="https://www.youtube.com/watch?v=6Ds0Bn7oF7c" target="_blank">http://www.youtube.com/watch?v=6Ds0Bn7oF7c</a>

The mushroom injector with the new spring. Looks good.

<a href="https://www.youtube.com/watch?v=bCXCwJt1Ci4" target="_blank">http://www.youtube.com/watch?v=bCXCwJt1Ci4</a>

Now I need to find time for some running trials.
Best regards

Roger

Offline Admiral_dk

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Re: Fuel Injection Systems Part 2
« Reply #122 on: March 25, 2023, 12:17:07 PM »
My guess is that the Injector in the first video is the best, followed by the last - and that the middle has a too concentrated cone ....

Test runs might prove me very wrong  ;D

Looking forward to see the Test Results  :ThumbsUp:   :cheers:

Per

Online Kim

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Re: Fuel Injection Systems Part 2
« Reply #123 on: March 25, 2023, 03:58:00 PM »
Such fascinating, detailed work, Roger.  I love the careful, methodical way you go about building and testing your injectors!
I learn a lot from following your posts!

Kim

Offline jcge

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Re: Fuel Injection Systems Part 2
« Reply #124 on: March 28, 2023, 11:34:28 PM »
Hi Roger - I echo Kim's comments above.
Taking such time to develop your ideas, methods and to share your results is greatly appreciated
John

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #125 on: April 15, 2023, 02:35:57 PM »
Thank you all for your comments and support  :ThumbsUp:  :ThumbsUp:

A couple of the bodies had 2.4mm spring seats which I bored out to 2.5mm using a 2mm endmill as a boring bar.

I had previously made two nominal 10° needles. One works quite well and the other tends to jam. 10° is quite close to a self-locking taper so I needed to check what I actually had. A bit of experimenting with my protractor allowed reasonable measurements. The one that jammed was around 8°, the one the worked and the one from the last running trials were 10°.

I decided to try a 12° needle as well. I made a pair as before and selected the one that was the best fit in the body. The initial test had a lot of big droplets but this improved with some more lapping.

10° needle:

<a href="https://www.youtube.com/watch?v=FDyp44PP63o" target="_blank">http://www.youtube.com/watch?v=FDyp44PP63o</a>

12° needle first test:

<a href="https://www.youtube.com/watch?v=SB3FpXEC6t8" target="_blank">http://www.youtube.com/watch?v=SB3FpXEC6t8</a>

12° needle after more lapping:

<a href="https://www.youtube.com/watch?v=DFYyD5ss6KE" target="_blank">http://www.youtube.com/watch?v=DFYyD5ss6KE</a>

Time for some running trials  :)

Best regards

Roger

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #126 on: April 16, 2023, 12:56:52 PM »
I had some interesting but not very successful trials  ::)

The new needle injector started and ran immediately but was quite inconsistent. None of the 4 mushroom/pintle injectors ran but one produced some thick black clag from the exhaust rather than the usual unburnt fuel  :headscratch:

I then went back to the needle injector. It ran, but not stably, as before then there was a loud pop and the engine stopped and would not restart. The exhaust pushrod had dropped out due to an excessive clearance  :toilet_claw:

As there was no adjustment left on the screw I called it a day and started to pack up. When I pulled the fuel pipe off the injection pump to drain the fuel back into the container the pipe had become unsoldered  :( Maybe this was causing an air leak and some of the inconsistent running  :thinking:

More work to do.
Best regards

Roger

Online Kim

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Re: Fuel Injection Systems Part 2
« Reply #127 on: April 16, 2023, 04:42:49 PM »
The lab tests continue!  :popcorn:
Sorry that they weren't as successful as you'd hoped, Roger.  Hopefully resoldering the pipe fixes the issue and you can continue with your fascinating learning process.

Kim

Offline Admiral_dk

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Re: Fuel Injection Systems Part 2
« Reply #128 on: April 16, 2023, 08:11:43 PM »
Thinking out Loud - I wonder if that very long and unsupported Copper Fuel-Line between Pump and Injector, vibrations + posible resonance => breakage @ the ends  :noidea:

Some of your spray patterns are good (close to very good, if it wasn't for the bigger droplets present too).

Still hoping and wishing for your complete succes Roger  :ThumbsUp:    :cheers:

Per

Offline steamer

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Re: Fuel Injection Systems Part 2
« Reply #129 on: April 16, 2023, 09:29:26 PM »
Even a bad result is a good one!   sounds like a "reset" and try it again .     

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #130 on: May 06, 2023, 04:03:49 PM »
Thank you all  :)

I resoldered the fuel inlet pipe and then started to analyse the injectors.

The spray pattern from the mushroom injector that gave the thick black clag was tight with minimal big droplets.

The result from the needle injector was poor and I felt that the needle wasn’t sealing. When I took the nozzle off the needle was stuck, suggesting the engine was running (badly) with a 0.2mm open hole. Maybe a slightly smaller hole would run, avoiding most of the sealing problems. 0.15mm should be possible, maybe 0.1mm.

I felt that the needle was sticking/jamming due to the long (20mm) bore that the it runs in. This was reduced to 10mm by drilling first 10mm out to 2mm.
The pattern was still not improved so I will make a new needle.
Best regards

Roger

Offline Admiral_dk

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Re: Fuel Injection Systems Part 2
« Reply #131 on: May 06, 2023, 06:36:55 PM »
I really wish that I had the knowledge to tell you what to do .... but if I did - I would have done it a long time ago.

I have only see the spray from an old 'Oil-Burner' (Oil Boiler according to Google) and from the 'Carburator' on a 'Velo Solex' (French Moped) - this is actually a low pressure Fuel-Injection System and not a Carburator.
In both cases a very fine 'Mist' (I couldn't see any droplets with a preteen eyevision) - coming out as a cone ....

I have seen a number of press releases from introductions of new Motorcycles (or upgraded versions of a model) - 'More holes of a smaler diameter than previous xxxx, results in a better atomization of the fuel -> more complete combustion -> more power and better fuel economy'.
In your case more holes are not needed - but a smaler diameter might help .... as you think about doing.

Per                 :ThumbsUp:     :cheers:

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #132 on: May 15, 2023, 07:18:27 PM »
Thank you Per  :ThumbsUp: As you know I am just making it up as I go along  ::)

I Turned up a new needle and lapped it to fit the bore and into the nozzle seating. The pattern looks somewhat better  :)

I had another look at the first new generation needle injector and the bore has significantly drifted off centre so to be recycled  :(
Best regards

Roger

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #133 on: August 28, 2023, 05:58:17 PM »
As the diesel appeared to run with the needle stuck open and just a 0.2mm orifice I decided to make a simple open injector with a non return valve.

The nozzle was turned from brass, which may have a limited life but will show if it will work or not. The non return valve is based on the injection pump delivery valve. Setting all the depths for drilling to gat a suitable length orifice is a little tricky but I seemed to end up with around 0.5mm.
Best regards

Roger

Offline Roger B

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Re: Fuel Injection Systems Part 2
« Reply #134 on: August 28, 2023, 06:04:26 PM »
Not much special about the body, the bore was reamed 2mm and the ball seating was lapped with a 3mm diamond ball lap.

The injection seems to be more of a squirt than an atomisation with the hand test pump:

<a href="https://www.youtube.com/watch?v=S9XOfphk89w" target="_blank">http://www.youtube.com/watch?v=S9XOfphk89w</a>

<a href="https://www.youtube.com/watch?v=fS5owr5DIJQ" target="_blank">http://www.youtube.com/watch?v=fS5owr5DIJQ</a>

A mushroom injector appears better:

<a href="https://www.youtube.com/watch?v=9D-_l4zTTv0" target="_blank">http://www.youtube.com/watch?v=9D-_l4zTTv0</a>

As does the latest needle injector:

<a href="https://www.youtube.com/watch?v=V5M0mXQIXQ8" target="_blank">http://www.youtube.com/watch?v=V5M0mXQIXQ8</a>

Hopefully I can do some running trials in the next couple of weeks  :)






Best regards

Roger

 

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