Author Topic: Fuel injection systems  (Read 52740 times)

Offline Roger B

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Re: Fuel injection systems
« Reply #210 on: December 18, 2018, 10:10:59 AM »
I think you are right about the injector shaking, I was concentrating onholding the camera in one hand and turning the engine with the other. If not that would have been an excellent spray pattern for the Junkers  ::)
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Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #211 on: July 29, 2019, 06:57:32 PM »
Having reached a bit of a dead end on the diesel with the 'conventional' nozzle design I decided to try some further experiments with the mushroom needle design. The first attempt was based on a 2mm shaft and is working fine on my horizontal petrol engine. For this series of experiments I have reduced the base size to 1.4mm. I have made two nozzles, one with a 30░ angle and one with a 40░ angle. Both were turned on my Proxxon PD150. As I don't have a tailstock die holder for it I glued a washer on the back of my small die stock to help keep things square. The M2 2mm AF nuts were made a while ago in anticipation of this step.
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Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #212 on: July 29, 2019, 07:00:27 PM »
The second needle was made in the same way and then I moved onto the nozzle and body. As they are both from hex bar I started with the 3 jaw sc chuck and will move to an ER chuck for the final steps.
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Roger

Offline Admiral_dk

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Re: Fuel injection systems
« Reply #213 on: July 29, 2019, 08:32:12 PM »
Glad to see that you found another "angle" to try and solve the problem from  :ThumbsUp:

I really hope that you will "nail it" this time - nice start to the first parts of the next gen. :cheers:

Offline Roger B

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Re: Fuel injection systems
« Reply #214 on: August 01, 2019, 01:47:14 PM »
 :)  :)  :)  :)  :wine1:

As the nozzle is quite short I used my ER11 chuck to complete it. The nozzle was drilled 1.3mm and reamed 1.45mm based on experience with the other injectors. The bore that the cone seats in needs to be round. I did consider lapping but will try without. The seating for the fuel supply union was cut with a centre drill and seemed to fit well with a Regner 2mm union and nut. When I first tried to assemble it the spring jammed on the needle so I drilled a small recess to keep it central.

Next step is to harden and polish the needles followed by a trial with petrol on the horizontal engine.
Best regards

Roger

Offline Ye-Ole Steam Dude

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Re: Fuel injection systems
« Reply #215 on: August 01, 2019, 03:46:19 PM »
Hello Roger,

Like the others, I do admire your efforts and appreciate the various parts that you are making.

Have a great day,
Thomas

Offline Roger B

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Re: Fuel injection systems
« Reply #216 on: August 01, 2019, 03:55:54 PM »
Thank you Thomas  :ThumbsUp:

I hardened the ends of the two needles and then had to set up the Proxxon drill for polishing. The 30░ setup was fairly easy but to get enough space for the 40░ one I had to turn the drill support upside down and had very little clearance against the milling column. I need to look at a more compact toolpost grinder system, maybe even one that will fit the PD150  :thinking:
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Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #217 on: August 10, 2019, 05:29:30 PM »
I made a clamping plate to suit the new injector and connected it up to my horizontal engine. Priming the system took some time as there is quite an volume in this style of injector compared to the needle type. Once primed I fitted it to the manifold and the engine started up without any problems. The response seems similar to the other injectors. One problem I found was that overtime the stroke adjusting system has become looser and now vibrates round on its own  ::) not useful  :toilet_claw: I am not sure whether just to add a friction spring somewhere or to make a new system that I can couple to the throttle opening  :thinking:

I also need to think about spring pressures for the diesel trials. With the needle type the compression pressure will tend to open the valve. With the mushroom type compression will tend to keep it closed  :headscratch:

« Last Edit: August 11, 2019, 07:49:39 AM by Roger B »
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Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #218 on: August 11, 2019, 08:04:41 PM »
While looking at  a solution to the adjustment screw problem I realised that when I changed the petrol feed pump the pipe ended up much too close to the exhaust system. This was quickly corrected. There was enough material in the stroke adjuster that I could drill through 2.5mm and tap M3 for about 4mm deep. I turned a little pressure plug from 2.4 mm brass rod and using a piece of the 1.4 mm injector spring made a spring loaded clamp. This seems to work and also stops the adjustor block tipping as plunger moves. Ready for some more trials  :)
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #219 on: August 18, 2019, 07:00:50 AM »
I decided that I needed to make a simple test pump for the injectors, fixed stroke and without a helix. There was a 18mm stub of 1.98mm pin gauge left from the previous pumps so I scaled it around that. The end of the gauge was annealed and threaded M2.
The frame is from piece of 50mm angle iron roughed out in the band saw. The spring seat as turned and the body bored and reamed as before.
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #220 on: August 18, 2019, 07:47:53 AM »
I reversed the body in the chuck and drilled 4.5mm dia 4mm deep for the delivery valve thread and milled the seat to 4.5mm deep. This is where the problems started, there were no threads at the start of the hole  :headscratch:  :( I made a new body and got much the same result  :thinking: this is something I had done at least 10 times before. Then I realised the difference, previously I had used a 'once through' M5 x 0.5 tap. This time I had used a pair of progressive taps I had bought as I thought that they should be better in blind holes. They are all Volkel taps so the quality shouldn't be a problem. So cut a new blank and try again  ::) My metre length of 10mm black bar is slowly disappearing with my injection experiments.
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #221 on: August 21, 2019, 07:39:17 PM »
The third version was no better  :( After some thought I tried with a  piece of 3mm flat bar. This was drilled first 2mm and then 4.5mm using the same drill. I then tried the once through tap, the progressive taps fully through and the taper just three turns followed by the plug. All were good threads  :headscratch: I then tried from the other end of the three trial (scrap) pieces, drilling 4.5mm again with the same drill. Once through tap pushing was ok. Once through tap with very light pressure was ok. Tape followed by plug was ok  :headscratch:  :headscratch:  ::)
I turned yet another body and tried again using the once through tap but withdrawing every couple of turns to see if all was ok. No problems  :thinking: Finally I milled the valve seating but there was plenty of clearance between the endmill and the thread so no problem there.
All is underway again but I have no idea what was going wrong  :toilet_claw: and hence no idea how to avoid it when I drill and tap the inlet port.
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #222 on: September 02, 2019, 05:27:35 PM »
The inlet port was drilled and tapped without problems as were the fixing holes. The bore was then lapped to size and the body was cleaned in the ultrasonic bath. A bit more work on the bracket and then the tappet for the plunger was turned from 10mm silver steel and hardened.
Best regards

Roger

Online Vixen

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Re: Fuel injection systems
« Reply #223 on: September 02, 2019, 05:44:33 PM »
More fiddly small parts. Nice  :ThumbsUp: :ThumbsUp:

Not sure my eyes would let me make those without a magnifier headband.

What ultrasonic bath do you use? I bought a cheap one once, it lasted a month before it failed. I may try again.

Mike
It is the journey that matters, not the destination

Offline Roger B

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Re: Fuel injection systems
« Reply #224 on: September 03, 2019, 07:20:48 AM »
Thank you Mike  :ThumbsUp:  :wine1:

There was a thread on ultrasonic baths a little while ago:

http://www.modelenginemaker.com/index.php/topic,8499.msg184738.html#msg184738

Mine is just a cheap (as far as cheap is possible in Switzerland) unit from Conrad.
Best regards

Roger