Oddball engines and prototypes

[Frits Overmars]

A prototype for a CVT transmission that uses gear

That CVT transmission is bogus, Shane. the only infinitely variable in the whole setup is the rpm of the electric motor, and that is accomplished in the usual way via a frequency generator. The gears are only there to enhance the controllable amount of torque at the cost of reducing the ratio spread of the electromotor. But the gears do not vary anything.

By the way: I just discovered this oddball-thread by mistake. It's great, but how on earth do you kiwis find the time to contribute to all those threads?

[Frits Overmars]

This is a good description of Honda's Moto GP seamless gearbox (was looking for this when I came across the silly video above) However, Yamaha have now gone the same way and are leaving the Honda behind! http://www.highpowermedia.com/blog/3212/motogp-transmissions

think I'm slipping behind with all these new inventions.... Maybe I'll have to go back to looking at the ESE thread again

Then you might want to start here, Will: http://www.kiwibiker.co.nz/forums/sh...post1130431455
The picture you posted on the previous page shows a Zeroshift seamless gearbox; Honda uses a fundamentally different approach.

[WilDun]

That CVT transmission is bogus, Shane. the only infinitely variable in the whole setup is the rpm of the electric motor, and that is accomplished in the usual way via a frequency generator.
but how on earth do you kiwis find the time to contribute to all those threads?

I had looked at that one maybe a couple of years ago and thought I would like to copy it (as near as possible) but I never really looked into it in any depth. As I saw it then, the gears seemed to be acting like an amplifier for a very small controllable electric motor and I think that's probably what you are getting at - but as I say I didn't really go into it and as my mind grows more feeble I may never do that! - same thing goes for seamless gearchange transmissions which I still haven't completely grasped! - Doesn't stop me from being interested though.

As for hydrostatic type transmissions, I think they are too inefficient for small engines (motorcycles cars etc.) however they are used a lot in earthmoving industry.
I once had a great pile of old swasplate pumps and motors under my bench for experimenting with, (for a couple of years I worked for a company who manufactured hydraulic pumps and motors ) but I never had the time then to do anything and they all got dumped when we downsized to a smaller home.

There was a Swedish company back in the seventies, who built a prototype motorcycle for the military (Hagglunds from memory) fitted with this type of motor/pump setup, but it just seemed to disappear into the haze of history. Think I've got an article on it in an old scrapbook somewhere.

I am retired and sometimes have the time to think about these things, as well as experimenting with metal casting in my garage/workshop - but then, only in between grandchild minding sessions - they come first (that's how it seems anyway).

I will look through the link you gave me a little more thoroughly, seems to be very interesting.

[Frits Overmars]

....seamless gearchange transmissions which I still haven't completely grasped!....I will look through the link you gave me a little more thoroughly, seems to be very interesting.

Seamless transmissions enable gear changes while the engine still delivers its full torque through the gearbox, so there is no need to close the throttle, cut the ignition or interrupt the injection. In a normal gearbox, when you engage two gears at the same time, the whole thing blocks and you'll get hurt.

You'll find the working principle of the Zeroshift box explained here:
http://www.youtube.com/watch?v=HJHji...yer_detailpage
http://www.youtube.com/watch?v=UL5h-...yer_detailpage
http://www.zeroshift.com/transmissio...animation.html

The Honda seamless box performs the same function, but via a different principle.

The clutch and the primary gearbox shaft of the Honda gearbox are quite conventional; they could have come out of an old Maico, Zündapp or Simson engine:


All secrets are brought together in the secondary gearbox shaft:


This secondary shaft looks like a cylinder from a security lock, with pawls that are operated from the inside by a rod that slides through the hollow gearbox shaft:


The essence of the Honda box can be seen in the picture below. The pawls in the shaft connect and disconnect the gears to the shaft:

In this drawing a tumbler Rao connects the gear to the shaft when the gear is rotating clockwise. And a tumbler Rbo is connecting the gear to the shaft when the gear is rotating anticlockwise. So in this drawing the gear is locked to the shaft.
The tumblers are governed from within the shaft via an axially moving rod.

Now if we perform an upshift, the shaft will need to rotate faster than the gear. Let us assume that the shaft is rotating clockwise. So we need to retract tumbler Rbo. Now the gear can still drive the shaft, but the shaft cannot drive the gear any more.

Next we engage tumbler Rao of the next gear, so it can also drive the shaft. Then we retract tumbler Rao of our original gear, so it can now freewheel in both directions. And finally we engage tumbler Rbo of the next gear so that it is now locked to the shaft.
That's all, folks: transporting torque from the gears to the shaft without interruption, both while shifting up and down.

Honda has filed patent applications for their seamless gearbox in Japan and the United States (patent applications 2010-203478 and US20110023639, respectively).
You can download the US patent document here: http://www.freepatentsonline.com/y2011/0023639.html

[WilDun]

That's all, folks: transporting torque from the gears to the shaft without interruption, both while shifting up and down.

Thanks very much Frits, - seems to me that with with this type of change gearbox and an engine with a little bit of torque (ie not "peaky" like the sixties and early seventies) then the normal automatics and CVT are not really needed anymore ie. so long as the cost of producing it can be reduced to acceptable levels.

[Frits Overmars]

Thanks very much Frits, - seems to me that with with this type of change gearbox and an engine with a little bit of torque (ie not "peaky" like the sixties and early seventies) then the normal automatics and CVT are not really needed anymore ie. so long as the cost of producing it can be reduced to acceptable levels.

These seamless boxes only came into being because CVT is not allowed in racing. No more than six gears are permitted, and CVT counts as an infinite number of gears. I'd choose CVT any time. It would give the rider (and the tuner) a much easier time and it would be ten times cheaper to produce than the Honda seamless gearbox.

By the way: I added some more text to my previous post. I thought I'd mention it, after I complained myself about not noticing texts that were added afterwards.

[WilDun]

These seamless boxes only came into being because CVT is not allowed in racing. No more than six gears are permitted, and CVT counts as an infinite number of gears.

Never mind, maybe I'll add a seamless box to my little lathe ( in the past I have used lathes with pre-selector gearboxes, these were a joy to use). you just selected the gear you wanted and when ready, just pressed a button and it changed gear.
BTW I have got a bit behind with the latest transmission trends - have CVT systems been perfected for other vehicle use now? How do they work? are they still based on the old DAF system, or have they moved on?

[husaberg]

Never mind, maybe I'll add a seamless box to my little lathe ( in the past I have used lathes with pre-selector gearboxes, these were a joy to use). you just selected the gear you wanted and when ready, just pressed a button and it changed gear.
BTW I have got a bit behind with the latest transmission trends - have CVT systems been perfected for other vehicle use now? How do they work? are they still based on the old DAF system, or have they moved on?

My mitzi has a electronically controlled CTV it has a manual model up and down (the computer selects the places where it is hydraulically locked) as a 6 speed.
The ratios of the gears in paddle selected manual mode are actually varied by the computer depending on how I am driving. it can also operate in a Constant CTV mode.

While this Is all pretty amazing if it goes pop it would cost more than $8000 to fix.
I would have rather had a manual.

[Frits Overmars]

I have got a bit behind with the latest transmission trends - have CVT systems been perfected for other vehicle use now? How do they work? are they still based on the old DAF system, or have they moved on?

DAF started by copying an existing rubber V-belt CVT, like the DKW Hobby scooter had. Then DAF developed a push belt, built up of steel elements, that ran with a lot less friction and could handle more torque. It was marketed by Van Doorne Transmissions, it even figured in a Williams Formula 1 car (but this was quickly forbidden by the FIA) and nowadays the whole world uses this idea. It is particularly popular with Japanese car makers. There were of course attempts to circumvent the Van Doorne patents, the most well-known being the Audi CVT chain.

[WilDun]

Awake early this morning for some reason.
I did use the 'tiptronic' system when we hired a Mitsubishi Lancer a few years ago, it was a joy to use I must say, but is it a manually (optional) controlled CVT or old fashioned automatic?

Is there any problem with slippage with the CVT transmissions, being (as I see it), friction drives?

BTW I owned a DKW Hobby scooter for about a year, but that was a long time ago ......... also a Triumph Tigress, that was a very good handling machine, better than some of the 'proper' motorcycles I had!

[Mental Trousers]

I did use the 'tiptronic' system when we hired a Mitsubishi Lancer a few years ago, it was a joy to use I must say, but is it a manually (optional) controlled CVT or old fashioned automatic?

The only TipTronic transmissions I've found to be any good are the twin clutch setups from the VW group of cars - VW, Audi, Skoda, SEAT etc. Most TipTronics you push the lever and then piss around waiting for it to decide it's going to change at it's normal change point anyway. With the twin clutch DSG boxes you push the lever and it's changed before the lever has hit the stop, it's as close to instant as you can get.

[WilDun]

The only TipTronic transmissions I've found to be any good are the twin clutch setups from the VW group of cars .

Oh ....... guess I'm at least 15 years behind the times - hadn't even heard of "tiptronic" before I hired that car and I thought then that I must be right on the cutting edge, should've gone to 'spec savers' then I'd have been able to keep abreast - sometimes I feel the need to catch up, but then why should I? - I'm happy being where I am at the moment! (Happy Daze)

[Flettner]

It's got nothing to do with high performance or competition, the crank arrangement and the movement of the piston and rod is the main thing of interest here, the rest is pretty ordinary and has most probably been done before, but if you look at the patent (there's a link to the patent there somewhere) it has everything covered and whether they ever use it or not, they've got everything sewn up and I very much doubt that keeping the patent going would be any problem for Honda!

Come on, what in this picture is actualy patentable, it's all been out there for years. This must be a ruse.

[Mental Trousers]

These seamless boxes only came into being because CVT is not allowed in racing. No more than six gears are permitted, and CVT counts as an infinite number of gears. I'd choose CVT any time. It would give the rider (and the tuner) a much easier time and it would be ten times cheaper to produce than the Honda seamless gearbox.

Interesting you should say that. I'm looking for a replacement for my Golf GTi and my mechanic, who is also a sponsor for my racing, has told me to stay the hell away from CVTs. Even on 2015 model CVTs he won't even change the transmission oil. Interesting cos he's up to ears in variable valve trains and alsorts of complex technical stuff, but he refuses to have anything to do with CVTs.

Given that I trust his word on all things car related I'm going for a twin clutch DSG seeing as it's bloody near impossible to find a modern manual these days.

[WilDun]

it's all been out there for years. This must be a ruse.

I'm sure you're right, but why did they bother to patent it?
Certainly not the major breakthrough as it's said to be I guess, however, its new to me - never seen it before!

The nearest I can think of is the old metal shaper drives (although they are basically 'Scotch Crank'). So it could be used for variable stroke I guess!