Subject: Re: Brian's Live Diesel Tue Mar 26, 2013 9:33 pm
Even if it's half ready we'll make room somehow!
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Thu May 16, 2013 3:34 pm
I think my frustrations with "engrenages" gears have been well aired on other threads so I decided to try a different route...
I know that Carl, Troy and others have experimented with "direct" drives from i/c engine to brushless motor with varying degrees of success, reverting to the use of clutches and pinions.
Being of a somewhat obstinate nature, I decided to have a go myself, exploring three options...
Rubber coupling
Proving to be far too long to fit comfortably in a Baguley chassis, but OK for a bigger model. Usual problems of grip with grub screws
Universal joint
Potentially OK, but still far too long and unstable
It was then that I noticed a series of mounting holes on the rotating body of the brushless motor...
Could then the motor be directly mounted to the Kyosho flywheel becoming simply an extension of the motor itself and thus avoiding the problems of torque and slippage with grub screws on 5mm and 4mm shafts.
1. Remove two spigots from one Kyosho flywheel 2. Drill out and mount this Kyosho flywheel direct to the brushless motor (Use "nutlock" throughout) 3. Then remove M5 extension from engine, shorten thread and remount flywheel with a an M5 nut 4. Press fit the two units together in a vice, and voila a single unit..
Here compared with an UJ
I think the natural extension of this approach for those that have lathes and engineering skills is to incorporate some kind of cooloing fan into the "double" flywheel design????
Carl Hibbs Admin
Location : Haute Normandie - visitors welcome
Subject: Re: Brian's Live Diesel Thu May 16, 2013 4:21 pm
Very enterprising and I'm always keen on other people's developments.
Obviously you haven't tried these in action yet.
I'll be surprised if the red UJ lasts more than a few seconds. Be careful of the flying pieces.
The other rubber coupling looks interesting. How is it constructed/connected to the 2 metal pieces?
The idea of mounting the alternator directly on the flywheel could be a real step forward. A long time ago I looked at a Canadian aircraft engine with a similar arrangement and was then drawn to a motorcycle dynamo, many of which are mounted around the crankshaft. See this pic for an example: M/C dynamo. I never pursued the idea though.
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Thu May 16, 2013 5:15 pm
Not sure of the bonding but it seems very tough, the shafts could also be shortened. Do you think a GX12 can run without a flywheel if it's connected via a shaft to the alternator?
Carl Hibbs Admin
Location : Haute Normandie - visitors welcome
Subject: Re: Brian's Live Diesel Thu May 16, 2013 5:19 pm
It will run but it doesn't start very well. I tried this with Van's diesel, no clutch, directly connected gears and no flywheel. It seems to need the flywheel when hand starting.
dtsteam
Location : Preston, England
Subject: Re: Brian's Live Diesel Thu May 16, 2013 5:48 pm
I like the direct coupling, but I'm not sure I could get the second flywheel to run true. It will be interesting to see how smooth it is when you fire it up. I do have a lathe so I'm tempted to have a go at a solid coupling.
Carl Hibbs Admin
Location : Haute Normandie - visitors welcome
Subject: Re: Brian's Live Diesel Fri May 17, 2013 5:00 pm
Taking this a stage further and going back to the radial motorcycle dynamo idea why not make the Kyosho engine crankshaft spigot the rotor of the BLDC motor?
First seperate the rotor casing and the stator by removing the e clip at the stator bearing. You would need to knock out the rotor shaft from the BLDC motor casing which for the 910 and 790 KV models from RC timer is 5mm - the same dia as the Kyosho crankshaft spigot. This is only located by grub srews to the casing boss but still tight fit. Then fix the the casing with the permanent magnets to the crankshaft spigot with the open end facing away from the engine block. The crankshaft spigot will then run in the bearing of the stator when refitted. There is even a slot in the end crankshaft spigot for an e clip to fit over the stator bearing. Then you just need to stop the stator from turning with a simple bar or anti rotational attachment. It may even stay still by attaching the 3 power cables.
If you have followed all that then I'm impressed, however the downfall is that the Kyosho crankshaft spigot is too short... blx!
But.... there are some very flat large diameter outrunner motors available that are used for 'multicopters' and 'gimbals'.
I am also looking at a PC hard drive motor which is very flat......
If any anyone is a good machinist (not me) you could make up a longer crankshaft spigot.
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Fri May 17, 2013 5:22 pm
Well the simple double flywheel solution it seems to have worked...
The following video is a compilation of three or four trial runs this afternoon and so far so good!
There is none of the meshing noise that you get with gears and the whole unit is very compact and sits low down behind the Baguley drive motor
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Fri May 17, 2013 5:45 pm
dtsteam wrote:
I like the direct coupling, but I'm not sure I could get the second flywheel to run true. It will be interesting to see how smooth it is when you fire it up.
As you will see from my pic and video, the two flywheels are far from exactly true, however as the drive is effectively being transferred by the two clutch spigots it allows for variations in alignment. It will be interesting to see how long the spigots last in the long term! However the unit is very smooth so far and with the double flywheel very easy to start!
Carl Hibbs Admin
Location : Haute Normandie - visitors welcome
Subject: Re: Brian's Live Diesel Fri May 17, 2013 6:26 pm
....mmm suitably impressed so far.
So the only thing holding the BLDC motor to the engine then is the press fit of the flywheel spigots?
What about if you bolted the BLDC motor directly to just the one engine flywheel with some spacers to allow for the crankshaft-flywheel bolt?
See this in action in a week's time.....
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Fri May 17, 2013 6:46 pm
Carl Hibbs wrote:
So the only thing holding the BLDC motor to the engine then is the press fit of the flywheel spigots?
Not really, the spigots are free to move within the second flywheel. The rigidity of the unit is maintained through the mounting of engine and BDLC
Carl Hibbs wrote:
What about if you bolted the BLDC motor directly to just the one engine flywheel with some spacers to allow for the crankshaft-flywheel bolt?
That was my first thought, and It's probably worth a try but I think more vibration would be generated unless you can get perfect alignment!
I think ultimately an engineered extended crankshaft with the BLDC mounted directly on it will be the perfect solution as outlined in your earler post!
In the meantime robbing a second flywheel from a 10 euro motor and keeping the glow plug, pull start and other bits for spares is a better option than all that money I spent on clutches and pinions etc.
Carl Hibbs Admin
Location : Haute Normandie - visitors welcome
Subject: Re: Brian's Live Diesel Fri May 17, 2013 7:26 pm
So the flywheel spigots are acting like a (permanent) dog clutch.
The 2 flywheels and consequently engine and BLDC motor still have to be aligned pretty well near perfect though otherwise it will be eccentric.
You can't have the motor shaft/rotor out of line to the crankshaft. They must rotate on the same axis at least at the point of the coupling of the two flywheels. There can be some angular misalignement. I now presume this is what you mean.
I suppose it is easier to try and align both on the same axis rather than parallel when using gears and clutch.
If I can find some suitable hexagon bar I'll try and turn and thread a long 5mm crankshaft spigot on the lathe.
David Grantham
Location : Midlands, England
Subject: Re: Brian's Live Diesel Fri May 17, 2013 10:10 pm
Brian,
can you please explain what stops the stator rotating on your twin flywheel modification. Is it just the power cables or is the stator fixed to something. Also what stops the whole BLDC motor assembly from moving away from the ic engine if the flywheels are a loose fit with the spigots.
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Sat May 18, 2013 2:40 am
Carl Hibbs wrote:
So the flywheel spigots are acting like a (permanent) dog clutch.
Well I suppose you could call it that, but you'd have to remove either the alternator or engine to disengage it
Carl Hibbs wrote:
They must rotate on the same axis at least at the point of the coupling of the two flywheels. There can be some angular misalignement. I now presume this is what you mean. I suppose it is easier to try and align both on the same axis rather than parallel when using gears and clutch.
Forgive my lack of engineering nomenclature, yes it is much easier to ALIGN the two shafts given that the two factory produced flywheels engage perfectly with the spigots and the two units are effectively locked together when mounting. And yes the system does allow for some ANGULAR disparity when running.
BTW my 910kv BDLC has a 4mm shaft and is a different model to the ones I've seen on your models.
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Sat May 18, 2013 2:47 am
David Grantham wrote:
Please explain what stops the stator rotating on your twin flywheel modification. Is it just the power cables or is the stator fixed to something. Also what stops the whole BLDC motor assembly from moving away from the ic engine if the flywheels are a loose fit with the spigots.
Hi David, it wasn't clear from my pics, the servo was obscuring the important detail. The engine and BDLC are mounted on the same piece of aluminium chassis (outlined in yellow here) It was salvaged from an old French car radio picked up at a local boot sale "vide grenier" for 50 cents.
This end view with temporary fuel tank removed better shows the stator mounting...
Carl Hibbs Admin
Location : Haute Normandie - visitors welcome
Subject: Re: Brian's Live Diesel Sat May 18, 2013 6:00 am
Ah all is clear.....I can even see the small angular misalignement now.
I'm quite surprised it works (starting as well as running) but there you go, another example of a simple solution by chance and imaginatiion rather than sophisticated engineering design.
No need to do anything more if you're happy with it.
We'll have to add this 'Bushell coupling' to the nomenclature.
..I have some spare flywheels.
David Grantham
Location : Midlands, England
Subject: Re: Brian's Live Diesel Sat May 18, 2013 6:40 pm
Tx Brian.
I often wondered in the past if the same result could be achieved doing the same with an oldham coupling, brushed motor (for starting) and a support bracket like you have. I figure the alignment could be achieved using the coupling and then tightening the bolts in a slotted hole on the back plate.
Probably less likely to work than your assembly due to the stress on the bearing if using a heavier brushed motor, but maybe worth a try. There are proprietory couplings that mimic your pair of modified flywheels.
What a great subject this live diesel thing is, so many ways to achieve the final objective. Well done to you and Carl..
on the back platassumed the lini coul
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Sat May 18, 2013 7:27 pm
David Grantham wrote:
I often wondered in the past if the same result could be achieved doing the same with an oldham coupling, brushed motor (for starting) and a support bracket like you have.
I'm not sure what an "Oldham Coupling" is from your description Do you have pics / links ???
David Grantham
Location : Midlands, England
Subject: Re: Brian's Live Diesel Sat May 18, 2013 7:32 pm
Subject: Re: Brian's Live Diesel Sat May 18, 2013 7:55 pm
Brilliant! Have these been mentioned before in relation to our efforts?
Are they available in 4mm and 5mm shaft diameters?
David Grantham
Location : Midlands, England
Subject: Re: Brian's Live Diesel Sat May 18, 2013 8:15 pm
Yes they have been mentioned. They may not be as good a solution as they appear at first glance. They are not usually rated above about 10 krpm though this depends on angular as well as lateral alignment errors. The other down size is that if you are trying to use a brushed motor for starting as well generating then obviously the Oldham coupling does not provide a gearing facility as would spur gears or timing belts.
They are widely available in many shaft sizes usually with a clamp or set screw option. 4mm and 5mm bore sizes are commonly available. They sell for around a fiver per end piece and say a pound for the fusible centrepiece.
Since it is a rigid and adjustable coupling when static it may make alignment with the dc motor and back plate fixings easier to determine.
I have a number of these couplings and have just started testing them after my 3 month house maintenance program. I will report as soon as I have something useful to say.
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Sat May 18, 2013 8:20 pm
Having finally got a drive system I'm at least 50% confident in, I've invested some time on the r/c and controls...
A is the Throttle servo B is the Track/Off/Alternator selector C is the reversing switch (servo operated) D is the rx battery on/off/charger switch E is the rx battery charge point
Carl Hibbs Admin
Location : Haute Normandie - visitors welcome
Subject: Re: Brian's Live Diesel Sun May 19, 2013 9:53 am
Just one point that I thought of on reflection.
You said that originally you chewed up the gears/clutch bell twice and you had screeching.
I looked at an old clutch/gear mounting set up of mine (I might actually try out a Bushell coupling) and found that it was not perfectly aligned but I worked ok.
Are you absolutely sure that the gears you used for the BLDC motor are 'module 1'? There are similar imperial gear pitches that look and feel like module 1 but are slightly out. I wrote about this somewhere in another thread.
Why I say this is that I notice module 1 gears often come in shaft sizes 5mm and upwards. Your motor has a 4mm shaft and although module 1 gears exist with this they seem less available.
This would certainly account for the gears stripping.
GWhizz
Location : Charente, France
Subject: Re: Brian's Live Diesel Sun May 19, 2013 10:00 am
The pinions I purchased from Conrad were definitely Module 1. However I drilled them out from 3.2mm to 4mm and maybe that's where the fault lies, I don't have a lathe and used a vertical drill
I'm not sure how I ended up with 4mm shaft BDLC's I went to the link page from the Live Diesel resource page and these were the only 910kv motors I could find
Carl Hibbs Admin
Location : Haute Normandie - visitors welcome
Subject: Re: Brian's Live Diesel Sun May 19, 2013 10:14 am
You would have to really drill out the holes badly to cause such misalignement so I don't think that's the reason.
I have just ordered some very flat 730KV motors from Hobbyking with a 5mm shaft these may just fit directly on the end of the Kyosho crankshaft spigot.
Saint-Oblas
Location : Lyon, France
Subject: Re: Brian's Live Diesel Wed Feb 19, 2014 5:56 am
It seems you have changed your muffler for a home made one. Is it more efficient or is it just a question of space?