Noisy planetary gear

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deletraz
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Noisy planetary gear

Hello Everybody,

First of all, my English is not my mother tongue, so if you cannot read me properly, just let me know, and I will try to improve...:-)

I am new on this forum, but I read a lot of things about the VX-1, since I own one for about a year, with about 4'200 km.
I am - almost - totally satisfied with this great machine. When - and if - new LiFePo batteries will be officialy available the VX-1 will really be an even greater machine.

My only - and main - concern is the noisy planetary gearbox. I do not mean noise due to gear problems, but just the whirling noise due to the use of spur gear parts.
I plan to revisit it by using helical gear, or even better, double helical gear.
Helical gear offers about 30-33% more contact between teeth, and several teeth are always meshed together, dramatically reducing the whirling noise which is in fact due to small vibration each time teeth "mesh" and "unmesh" in each together.
I am pretty sure that we could have an almost totally silent planetary gearbox. After all, just drive a race car with spur gearbox versus a standard sedan car, and you will understand what I mean. Today's car gearboxes run very silently.

So the reason of this thread just because if I would take some of my time to build such a gearbox - either helical or double helical - for the VX-1, I could maybe offer a solution, at least for those who - like me - find that such a nice electrical vehicle producing such an horrible mechanical noise is just not great...

Or maybe that somebody already planed this and realized what I am looking for?

Herve - Geneva - Switzerland

R
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Re: Noisy planetary gear

such a nice electrical vehicle producing such an horrible mechanical noise is just not great...

I completely agree... How much would that new gears cost?

AndY1
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Re: Noisy planetary gear

I believe a user named Sai (or something like that) already suggested that he will make helical gears for his Vectrix. I think his post is at least 1 year old.

I think this is it: http://visforvoltage.org/forum/4592-vectrix-gear-noise-driving-me-crazy

Anderson
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Re: Noisy planetary gear

Here is some more on siai47 chronicling his not 100% successful building a helical planetary gear for his Vectrix. http://visforvoltage.org/forum/4193-mik-question-about-gear-noise

Can it be that no one can see the forest for the trees, I'm no gear expert but if you ask me I think this gear box tries to do to many things, namely being a wheel hub and a gearbox combined into one. Wind turbines have a
similar situation and consequently usually have a separate hub bearing to take the large axial loads thus greatly reducing the size of the input gearbox bearing which allows it to have much higher tolerances.

updated motor-hub.PNG

deletraz
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Re: Noisy planetary gear

Hello R,

Well, I don't know yet, since I will have to make a prototype with my CNC maker. It will mostly depend on how many I could produce.
I just wanted to know if Vectix owners would be interested in. You are the first to agree, so it is a good start... :-)
I plan to study and make a prototype during this summer, or early this fall.
My only problem is that I will have to dismantle my own bike, and I could not drive it during the sunny days... I am trying to find out a complete engine assembly, possibly out of order, but if I can't find one I will have to canibalize my own one...

I will keep you posted as soon as I will have started.

Herve

deletraz
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Re: Noisy planetary gear

Hello Anderson,

Thank you for your comment and the very nice picture!
Well, a planetary gear is to be seen here as a fixed ratio gear reducer, not like a automatic gear with planetary blocking scheme in order to obtain different ratios.
So the internal geometry is quite simple.

The biggest problem here is that when using helical gear, there is an axial force which is developed and then - you are right - bearing must be different.
Furthermore, when you accelerate the axial force is in one direction and when you brake using the electrical regen, the axial force is reversed.

The solution here would using double helical gear, but they are very costly to make. Another possibility is using twice the number of helical gear located in opposite way, thus cancelling all axial forces.

As I told R, I am thinking about this...

Hervé

deletraz
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Re: Noisy planetary gear

Hello AndY1,

Well, in the topic you mention, the problem was a problem of unbalanced gear. By relocating (swapping) planetary gear the noise has been reduced, but just to the "normal" level all Vectrix behave when there is no problem. What I am thinking about is a true modification which could lead to dramatically reduced noise by design.

Hervé

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Re: Noisy planetary gear

Wouldn't it be easier to redesign the rear swing arm? let's place the engine outside the wheel and transmit the power with a plastic belt like BmW?...

Mik
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Re: Noisy planetary gear

Wouldn't it be easier to redesign the rear swing arm? let's place the engine outside the wheel and transmit the power with a plastic belt like BmW?...

I think that might be too hard.

But a helical gear set will reduce the range.

I'd be quite happy with a perfectly well working straight cut gear box. When the standard Vectrix gear bow is working as it should, it is not too bad.

This information may be used entirely at your own risk.

There is always a way if there is no other way!

Anderson
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Re: Noisy planetary gear

Hello Anderson,

Thank you for your comment and the very nice picture!
Well, a planetary gear is to be seen here as a fixed ratio gear reducer, not like a automatic gear with planetary blocking scheme in order to obtain different ratios.
So the internal geometry is quite simple.

The biggest problem here is that when using helical gear, there is an axial force which is developed and then - you are right - bearing must be different.
Furthermore, when you accelerate the axial force is in one direction and when you brake using the electrical regen, the axial force is reversed.

The solution here would using double helical gear, but they are very costly to make. Another possibility is using twice the number of helical gear located in opposite way, thus cancelling all axial forces.

As I told R, I am thinking about this...

Hervé

I think you misunderstood me I wasn't making a statement about helical gears I was merely bringing up the point that when you use a disproportionately large sized bearing in a gearbox you are decreasing it's tolerances the more the bearing is larger than necessary. In the Vectrix's gearbox it might be a 6 times reduction in tolerances.

hub.PNG

Paul
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Re: Noisy planetary gear

If you try to re-manufacture the planitary gearbox with helical gears, you may well make the whole thing more quiet.
There are also a few other things to consider.
The motor shaft has a straight cut profile, how will a helical gear be incorporated? Perhaps turn down the original shaft and press on another helical sleeve? This may work if you are prepared to also replace the outside hub gear in a similar manner as well as manufacture intermediate gears to suit.
May I suggest a solution as pioneered by eyeinthesky, and that is to replace the intermediate gears with nylon replacements. This will isolate the mechanical noise of the motor shaft and outer gear and also eliminate most of the wear in the gearbox.
To replace the three intermediate straight cut gears with nylon replacements is not too dificult and any half-way competant machining shop can achieve this without dificulty as straight cut gears are straight forward.

Helical gears: I think Mik pointed out that they are quieter, but absorb more torque/power and therefore are not ideal in an EV drivetrain. Better to replace what we can with materials which will do the job better!

Cheers

Paul

deletraz
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Re: Noisy planetary gear

Hello Paul,

Well, you are right, with a simple helical gear you loose some torque and power because of the axial forces induced.
My plan is using double helical, in French they are called "chevrons", like used first in Citroen cars. Using them torque is not affected and there is no axial forces.
As it is very costly to design these, the best way is using to sets of helical gear installes face-to-face.
Of course the motor shaft will be redesigned, as well as the outside hub.

But, and your comment is very interesting here, using Nylon intermediate gear could be a very nice solution.
I will also consider this.

Thank you so much!

Hervé

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Re: Noisy planetary gear

My plan is using double helical, in French they are called "chevrons", like used first in Citroen cars.

I remember now. They used the look of double helical as their company logo:
//www.origincomputers.co.uk/images/categories/citroen%20Logo.jpg)
//imghost.indiamart.com/data/8/3/MY-1159703/double-helical-gears_10655385_250x250.jpg)

R
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Re: Noisy planetary gear

If double helical is better, why was abandoned? I don't remember any new engine using this kind of gears...

turok
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Re: Noisy planetary gear

Hey Deletraz,

Fyi,
Whatever the solution is, I'd be glad to spend some money to make my V quiter.

But whatever the cost, a reduction of the range would not be acceptable to me.

Nylon sounds good, but will it not fail/wear out?

"doing nothin = doing nothing wrong" is invalid when the subject is environment

deletraz
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Re: Noisy planetary gear

Hello Turok,

Yes, also for me, a recuded range wouldn't be acceptable, and Nylon wearing will have to be studied carefully.
But if go for the double helical solution, it will be full steel, not nylon. Nylon is just a possible solution in order to keep spur gear with some noise reduction.

Double helical gear was abandoned simply because the cost is prohibitive in machining. The trick here would be machining twice the helical gear required, then assemble them in a clever manner.
Double helical gear is silent and has no axial torque, and have even better efficiency than spur gear. Noise in a spur gear means some energy loss, no noise is less energy...

Herve

athlon
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Re: Noisy planetary gear

If double helical is better, why was abandoned? I don't remember any new engine using this kind of gears...

normal or helical gears can be made by machine , double helical can be made only by CNC , much more expensive (or by coupling 2 identical and opposite helical , with just the double of the cost of a single helical)

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Re: Noisy planetary gear

Ok Athlon. However, double cost and half noise make a lot of sense to me...

Keef Powling
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Re: Noisy planetary gear

YES BELT! why didnt they put the motor (INBOARD) + slap a belt on. no expensive + totally unnecessary noise, no stupidly heavy dead weight in the back wheel that makes the handling pathetic, just try cornering over any kind of bumps.. basicly vectrix has no pedigree in bikes , the frame is nice, but they lost the plot when they put the motor on. plus all the suspension is so inadequate (such a shame) plus theres the horn?? ..then theres the the lovely sickly safety concious controlled pull away ( probably a fudge to stop the skiping back wheel) ....but you NEED a bit of a kick pulling away, especially if your weaving thru traffic + you need to regain your balance ..... does any one get involved with tweaking the motor drive?

p.s. re. vibing motor..i think i'm gonna just put new r.wheel bearings. it just feels like a knackered bearing

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Re: Noisy planetary gear

.

R
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Re: Noisy planetary gear

Completelly agree. My wife has a govecs S 3.4, belt transmission, almpost 0 noise, it is like being in Heaven.
If only they have build an Electric TMAX!
2013-Yamaha-T-MAX-ABS-EU-Solar-Black-Detail-005[1].jpg

MEroller
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Re: Noisy planetary gear

Why not convert a T-Max to electric yourself? Others even do that with full-size cars :-)

My rides:
2017 Zero S ZF6.5 11kW, erider Thunder 5kW

R
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Re: Noisy planetary gear

LOL!
For the same reason I converted my vetrix with 2nd hand GBS cells, the ultimate dream barrier: MONEY!

Archi13
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Re: Noisy planetary gear

Reduce the weight is very important too for reduce the noise, of course.

Archi13
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Re: Noisy planetary gear

Hello all,
Noise what noise, my planetary gear is very quiet but I have a secret. After a thousand Km that I use these additive I forget the noise of my gear box.
http://www.warmup.eu.com/additifs-auto-gold-formula.html
I add just 10ml of these in the 80ml of the planetary oil and the silent is back.
http://www.warmup.eu.com/pdf/GF250.pdf

R
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Re: Noisy planetary gear

very interesting, Archi.
Alberto gave me an interesting idea:
The kevlar is a reinforced plastic, extremely resistant.
Now there are CNC machines that can cut Kevlar.

It may be possible to cnc kevlar gears to fit into the Vectrix's planetary system:V-kevlar.jpg

Three gears per vectrix. I guess that with this technology the vectrix would be extremely quiet...

does this idea make sense to you?

R
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Re: Noisy planetary gear

very interesting, Archi.
Alberto gave me an interesting idea:
The kevlar is a reinforced plastic, extremely resistant.
Now there are CNC machines that can cut Kevlar.

It may be possible to cnc kevlar gears to fit into the Vectrix's planetary system:V-kevlar.jpg

Three gears per vectrix. I guess that with this technology the vectrix would be extremely quiet...

does this idea make sense to you?

Archi13
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Re: Noisy planetary gear

2x

Archi13
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Re: Noisy planetary gear

Hello R,
I prefer knowing that my gears on my gearbox are on a good metal.

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