Im still trying to get my head around this one, and I only had a quick look at the engineering report. But I think Gizmag missed the problem in this update.
As I understand it a brake is all that is needed on the control shaft, not a powerful motor. When the brake is on full the drive is in top gear. When the control is allowed to move freely and there is a load on the output the drive will be in neutral.
The problem that I can see is that the brake on the control creates a source of friction and therefore energy loss.
17th May, 2010 @ 6:03 a.m. (California Time)
Perhaps a better use of planetary gear sets would be to combine them in series to produce a nine speed transmission and eliminate the need for gear reduction in the drive axle. Combined with a high torque engine - electric or long stroke diesel - you could achieve good performance and a one to one drive ratio with a smaller engine.
17th May, 2010 @ 7:51 a.m. (California Time)
It can be done with just two moving parts - I did it in 1982.
17th May, 2010 @ 8:22 a.m. (California Time)
How about instead of using a friction brake, you use a motor operating in reverse as a generator to recover the power? This is starting to sound like a perpetual motion machine, but it\'s really not (if your \"understanding\" is correct.)
17th May, 2010 @ 8:32 a.m. (California Time)
After reading the first article it occurred to me that you\'d still need a clutch at least to get started.
If you start a gas motor directly connected to the D Drive, you\'ll start in gear until some kind of motive force starts turning the other shaft and matches it exactly to the primary shaft\'s rotation speed. It seemed to me no matter how you arranged it the shaft speeds could not be matched from the initial cranking of the motor to the engine starting.
Hence at least for start up you need a clutch that maybe would only be needed at engine start and engine shut down, but it would be needed.
You could arrange a gear system that drives both shafts equally at start, but now after start up you need a way to disconnect that gear, again you\'d need some kind of clutch.
17th May, 2010 @ 9:12 a.m. (California Time)
If only it had been as stated. Just think, no clutch, no torque convertor, a semi pulling a hill, with just a lever to pull down to keep the r\'s up on the diesel. Darn it, I watched this video three times before I realized the torque pressure from the load would transmit back to the \"control\" shaft, (which was mislabled, should have been additional input shaft). My older brother, (80yrs), saw it immediately, and only watched 2/3 of the video to see it. This will work in a hybrid with electric on the \"control shaft\", and when you pull out on the highway, the infernal combustion is then added.
17th May, 2010 @ 9:31 a.m. (California Time)
I think this is a valuable lesson for GIZMAG. And a valuable and unrealized resource. I don\'t know how many people read this newsletter everyday but it seems to me that you have a very large number of interested and knowledgeable people. Why don\'t you send out a questionaire every day, in addition to one of your articles at the end? Also, why don\'t the authors start developing relationships with the best \"COMMENTORS\"? I mean if one \"OF THE CHOSEN\" have a suggestion, they could leave a quick voice mail or email or you could even have a video conference!!!
17th May, 2010 @ 9:47 a.m. (California Time)
HToad\'s comment bring me another idea. If we need to break the control shaft then we can attach an electric motor to it. Not for driving, just for breaking. We can convert this breaking energy to the main shaft with another electric motor.
We can eliminate most of the energy loss but the system become too complex I guess :(
I hope more ideas will come out. My 2 electric 1gasoline system doesnt look good.
17th May, 2010 @ 10:21 a.m. (California Time)
These are the very same concerns that came to mind for me upon reading the first article. The conclusion I\'ve come to (upon this article confirming my thinking) is -
With one main drive source/engine two D-drives would be needed, one for the main drive and one for the \'control\' drive. The \'control\' drive D-drive is then operated by an electric motor. I\'m relatively sure that the software is doable.
I sure hope some outfit gets it all going.
GOOD LUCK Steve!
17th May, 2010 @ 10:39 a.m. (California Time)
The control shafts could be driven by hydraulic motors powered by the same type of pump conventional automatic transmissions use.
Resistance to reverse torque would be simple to control by a variable orifice valve, possibly also with a quick acting one way valve that can be electronically enabled or disabled.
Another possibility, if the control shafts only need to rotate in one direction, would be one way roller clutches, also similar to those used in conventional automatics. They have next to zero resistance in their forward direction but quickly lock when torque is applied the other direction.
17th May, 2010 @ 3:41 p.m. (California Time)
ah well, they say pigs can\'t fly,,,,,,,,, bloody hell, there goes another one !
17th May, 2010 @ 6:44 p.m. (California Time)
@ HToad to Facebook User
It's nice to see the interest and ideas you people are expressing in your comments. But I have to regretfully inform you that the proposed ideas to solve the 'friction brake' or 'ratio control' issues efficiently have already been resolved and have been successfully implemented in the Prius Hybrid Synergy Drive. Please see comments from other astute readers and those from myself explaining this on the original article about the dDrive. If you are interested in the way the torque is controlled and some of the benefits of using the Prius system please find a rather lengthy explanation way down that same comments page.
@ froginapot Gizmag
I wholeheartedly agree with your comments on making Gizmag more interactive with its readers. One thing I suggested was to speed up the comments section, I have posted comments and they have taken over 5 hours to show up on Gizmag. I am not sure what is causing this delay and it tends to make any real discussion or information exchange impossible. Comments made do not and cannot 'self-correct' with such long delays in posting. Is it possible that Gizmags web servers are on Pluto given the time it takes for it to go up? ;) Maybe it would be possible to migrate the comments to a forum type environment and from there the authors can tag some reliable contributors? Just an idea.
@ Grunchy if you read this...
Which version of the Ikona transmissions are you referring to? The non-involute profile gears (aka Harmonic Drive) were used on the Lunar Rover in the sixties, but I have not yet found a variable speed/ratio version. Could you post a link to the actual drive please? Thx
17th May, 2010 @ 8:18 p.m. (California Time)
why not place a motor on each output shaft of a common differential? each could play as a power/control motor. The output shafts would then be the input shafts. The speed and power of the main shaft, now the output shaft would depend on the direction and speed of the respective input shafts.
18th May, 2010 @ 8:32 a.m. (California Time)
Well, since it has two input shafts, could a high torque electric motor be used as the second input? Electric motors have huge, instant torque curves...
Making an electric motor stay in \"stop\" position for full gear input is not that hard. The Segway does this with its two motors to stop itself. So in this regard I do not think a clutch would be needed for the second input shaft.
In this way the system could work with little energy input into the second shaft.
I am also wondering how much energy is needed to get the transmission into the neutral setting. Granted, it has to spin the shaft, but it is not powering a load.....
At that point the question would be whether the energy expended on the motor is justified by the simplicity and efficiency of the design.
As opposed to a six speed automatic, which are becoming common as auto manufactures seek better MPG....
Or am I still missing it?
18th May, 2010 @ 8:40 a.m. (California Time)
Poor Steve, it looks like you\'ve gone to huge effort to build a beautifully complicated model of something that has already been invented. I don\'t really care whether this has been used before in jet engines or Toyota hybrids and the other comments here do enough to knock it down on technical points.
The simple fact is that once you realise that the power of the input and control shaft needs to be balanced, then you could achieve the same result using any old differential or planetary gear set.
Keep trying Steve, but don\'t pump more money into this one!
18th May, 2010 @ 8:51 p.m. (California Time)
I\'m not sure why commenters are suggesting \'work-arounds\' for the \'control\' shaft (e.g. CVT & clutch to transition to neutral at start-up) when it works against the input shaft anyway. While an stop-start ICE would reduce the \'control\' shaft inefficiency there\'s no avoiding the energy loss when on the move just to maintain the required ratio. Solving the friction problem by meshing gears surely gives the inventor a clue that the assertion that the energy for the \'control\' shaft \'doesn\'t have to be anywhere near the energy that you\'re putting into the input drive because it doesn\'t have to work against that power\' (Gizmag presenter, but surely from the inventor) is ridiculous.
What astounds me is that an \'inventor\' would spend 20 years of his life working on something without doing basic research - even before the internet & Wikipedia made it simple. Why not just bolt an identical electrical motor to the input shaft of his plastic prototype and watch it freeze up? The use of planet gears (the essence of the \'invention\') for power-splitting is very old (well before Toyota used it to combine 2 motors), so why would anyone think that one motor can be almost independent of the other?
18th May, 2010 @ 9:41 p.m. (California Time)
While I haven\'t looked at this concept I am inspired to see so many people reading, discussing and thinking about an issue.
Does anyone know of any websites set up to collaborate in this way?
Surely if a problem is presented in a forum-type environment with a lot of smart heads we could pretty much solve every problem humans encounter.
It would also prove an invaluable resource for inventors to prevent them from re-inventing the wheel all the time.
Theoretically patents are meant to act as a repository of information in this way. However, i haven\'t met many people who find reading patents enjoyable. Perhaps we need smart software engineers and linguistic experts to automate scanning of patents to extract a catalogue of information and then tag appropriate articles of Wikipedia with links to relevant patents. !!
What do you think?
19th May, 2010 @ 2:07 p.m. (California Time)
This sounds like a decent proposal. I can only see one drawback and that is human nature. People making comments about how good or bad, or how to improve a product or idea, will only continue as long as there is no competition between the parties involved. I think the only way this \'good will\' can be fully utilized is if like minded and goal driven individuals contribute without regard for their own compensation. Patents tend to always restrict the idea to an individuals benefit, and this benefit is nearly always financial. I strongly believe that any idea should be the property of all, especially those who can make the most of it in their communities (not just to make themselves rich or powerful).
The world we live in \'likes\' to protect the rights of the individual, but if every individuals rights are protected who is going to protect the rights of the community? After all we can not survive alone no matter how many rights we have, and many of the rights we have come at the cost of others rights.
But there is hope for us yet, if we can learn to trust each other and put the needs of others before our own wants.
In the meantime though, a interactive technology website/forum would be the go. Maybe Gizmag or its readers could get something like this going. I notice they\'ve done something similar for the Gulf of Mexico oil leak, but it is in no way interactive.
19th May, 2010 @ 9:59 p.m. (California Time)
Two electric motors would work just fine. The electronics to control the motors\' relative speed should be pretty straightforward to develop.
24th May, 2010 @ 11:25 a.m. (California Time)
I dont understand all you people saying to use electric motors with variable speed drives. The electric motor itself is an infinitely variable transmission already!!!!
4th June, 2010 @ 3:04 a.m. (California Time)
You know what? It occurs to me that both shafts are being powered by the same source. Everybody is getting it all wrong because they think the control shaft has to be powered by another source when in fact they are being powered by the same source. Look at the video. They are rotating off the same drive shaft then power is leached to the second shaft, the control shaft, to SLOW the final drive down. Thus it leaches power only to decelerate in to a new ratio, not accelerate.
1st January, 2011 @ 6:52 p.m. (California Time)
Resurrecting this again - after recently viewing the video for the first time, I thought there has got to be a simpler way. While tossing and turning in bed last night, I \"invented\" the same thing, only way simpler using planetary gears. I had no knowledge of how they work, it was all thought experiment. It woke me up to the point that I got up and grabbed my iPad and started Googling. Lo and Behold, I had re-invented the Toyota Prius\'s Power Split Device (PSD)!
As has been pointed out, differentials and planetary gears are nothing new. The Prius proves they can be used in a very elegant way to blend vastly different power inputs in order to achieve a very efficient and smooth CVT and utilize two very different power sources (ICE and EM) in their most efficient operating regimes, respectively. I think it is clear the D-Drive is just an obfuscated and needlessly complicated version of Toyota\'s PSD wherein the control input shafts are like the Motor Generator 1 & 2 (MG1 and MG2) in the Prius Hybrid Synergy Drive system.
16th April, 2011 @ 10:34 a.m. (California Time)
I\'m amazed that people fell for this. The thing is just an obfuscated differential, as was obvious from the video.
The transmission of the Model T Ford worked on similar principles. It used a planetary differential with a brake band on the outside ring gear. Applying the brake to the ring gear made it transmit power, thus combining a clutch and a gearbox. That\'s essentially what the D-Drive is doing, but with about four times as many parts.
17th November, 2011 @ 10:16 a.m. (California Time)
rxcited is exactly correct. The Prius planetary arrangement is quite brilliant, someone deserves an award for that. A differential is equivalent in that it has 3 input/output shafts. This allows you to have two power sources in and one output. The D-Drive is just a very complicated example of this principle.
20th May, 2013 @ 12:54 p.m. (California Time)
Seriously this was done ages ago with tank drives and military vehicles.
Just go to youtube and watch the training video. . about 9 mins in they talk about using planetary gears and two inputs to deal with variable gear reduction. It's called "Planetary Gears, Principles of Operation, Multiple Sets 1953 US Army"
It's one of the basic principles of planetary gear systems. . .the rotational speed (tooth count) of the two inputs on the set maintains a speed between the two. With the lost speed being converted to torque. . . as all speed reduction does. . . . .the power is split between he two inputs and applied to the single drive output. . . .
why does this keep getting reinvented? That's the actual issue. . .I think it torques peoples head so much that they get confused and grant the patent again. .
29th September, 2013 @ 3:25 a.m. (California Time)
Use a torsen differential to split the power to the two shafts (input and control). Brake the control shaft to control its speed and the overall gear reduction. Of course effeciency will be lost through the braking action- but how much would depend upon the type of brake.
28th November, 2013 @ 7:20 p.m. (California Time)
multiple patents on the same principle, now if it can be shown to offer a big percentage on efficiency over other similar designs, then maybe a patent on that part of the design. Test ,test and retest, we need efficiency,not a repackaging of the same. I hope it is a step up
11th December, 2013 @ 10:02 a.m. (California Time)
I will give the short version: this is basically IMHO a differential gear setup. Once you accept that and stop concerning yourself with all the technical principles, and instead think about what you know of car differentials IN PRACTICE, you will figure what's wrong here.
In short, it's able to vary SPEED but NOT TORQUE.
And you all know why, because you've all been stuck in a patch of mud in a conventional, simple differential-operated car.
The wheel that is NOT turning when you are in the patch of mud - does it supply loads of torque, or is all the energy going into spinning the wheel that is already free?
That is correct - the wheel with NO GRIP spins its nuts off, pointlessly. The wheel with the grip, does not bother, because a differential gear arrangement is specifically designed to let the wheels run at different speeds, otherwise it would be like a solid axle, and judder as you drive around corners and the outer wheel needs to go faster to 'keep up' with the inner one, 'cos it has a smaller distance to cover.
Of course, all it needs is a brake attached to the freely-spinning wheel (shaft in Durnin's case) and then that would FORCE the other wheel to move! Hang on - that's friction. Oh dear.
To recap - it's a differential gear unit; it does NOT increase torque which is the whole point of gearboxes (making the engine put more revolutions in for every revolution of the wheel = mechanical advantage so more torque); his other motor is effectively producing a braking input to one shaft (by 'fighting against' whatever the natural free-spinning desire is of this er, invention).
Look, it came up in 2010 on youtube, and in 4 years apparently the guy never got some torque measurements.
That's it - a simple differential gear unit and like that device, it does NOT multiply torque on the SLOWER moving wheel (read 'shaft' here) and yet NEITHER does the FASTER-moving shaft have more torque.
Think differential, think free-spinning one of a pair of wheels (read 'shaft' here) and realise the reason it is difficult to get your head around is because this thing goes round and round in circles without doing the thing it is implied to do - it does NOT produce more torque as the output shaft is slowed down, nor does that happen at the other shaft that is spinning faster.
You can work out all sorts of additions to make it do something useful, but in practice, it'll need a brake on one shaft and some way of INCREASING the torque to the output shaft, to do anything other than bamboozle people. I am slightly surprised it made it to a plastic model, or that he did not simply modify a differential gear unit off an old car and try it on a go-kart or something, to verify that it could give a useful variation to torque on the output shaft.
Sorry, this is not what it's been billed as, or any new tech, or any real use. Took me 45 minutes to realise this, I am disappointed in myself!
7th December, 2014 @ 5:11 p.m. (California Time)
I registered just to comment on this story because of tone and detail of the conversation. I am NOT a mechanic, I am a computer nerd, but technical things still fascinate me. What I wanted to ask was if the D-Drive is just a IVT component, how did they get it working? See:
Or search youtube for the "Vrtddrive" channel if links are not allowed. The video doesn't show any technical details, but is it just a bluff?
17th December, 2015 @ 9:42 p.m. (California Time)