CVT gearbox explanation

[Chas G]

Watched this excellent video explanation of how cvt transaxle works. Worth a look.

https://www.motor1.com/features/706300/how-cvt-works/

Timoshenko's "Theory of Elasticity" will be covered next week. 🙂

[Mojo1010]

Is it any worthiness of you understanding the Toyota CVTe when "The theory of the 12v battery" is making you dizzy? 😂

[Chas G]

2 hours ago, Mojo1010 said:

Is it any worthiness of you understanding the Toyota CVTe when "The theory of the 12v battery" is making you dizzy? 😂

Yes but at least I didn't tell @Graham47 smart Yaris that I had already anticipated that my 12 volt Battery would be flat causing me to be on the hard shoulder hence my indicators would not be working in my previous post in response to you getting an Amber flashing light in the 12 volt Battery maintenance thread.

It's being so miserable that keeps him going tha knows. 🤪

Quote "I might buy a Battery powered one for my boot"

 

[Chas G]

@MOJOI saw this 245hp Skoda Octavia VRS at Marshalls garage in Reading today.

I wish I had bought it instead of a potential 1.5 ton 4 wheeled flat Battery, at least it would have been fun. 😁

[MikeSh]

2 hours ago, Mojo1010 said:

understanding the Toyota CVTe

That's not the 'e' version he's linked to, it's the mechanical 'DAF' one (that everyone uses a version of).

The Toyota e-CVT (aka HSD) is a completely different animal (and a lot harder to get the grey cells round than a CVT).

[Chas G]

1 minute ago, MikeSh said:

 

The Toyota e-CVT (aka HSD) is a completely different animal (and a lot harder to get the grey cells round than a CVT).

Timoshenko's theory of elasticity is a bit of a bugger to understand too. 🤔 

[Mojo1010]

46 minutes ago, Chas G said:

It's being so miserable that keeps him going tha knows. 

Quote "I might buy a battery powered one for my boot"

 

Yes had noticed you mentioned the Battery powered beacon. Practically its better than the wired 12v beacon, though it still drains a little Battery power especially in winter, unless checked and 'charged' periodically. 

My beacon's tucked in the boot, it will help in the event of a breakdown on fast roads at night 👍🏻

[Chas G]

@MikeSh i watched a video of someone explaining the Toyota hybrid system and I must admit that I would have had to make notes and watch it many times before I would grasp more than the general principles. As he was talking he was dismantling a transaxle and it had an incredible number of component parts.

[bathtub tom]

1 hour ago, MikeSh said:

The Toyota e-CVT (aka HSD) is a completely different animal (and a lot harder to get the grey cells round than a CVT).

I thought it was an epicyclic gearbox? If you can get your head round a conventional diff, then an epicyclic gearbox shouldn't be too difficult to understand.

The best CVT I've seen was in a Yamaha, petrol engined golf buggy. Lifting the seat revealed everything and it could be made to operate in 'neutral', as that was controlled by a forward/reverse lever that operated the back axle. The clutch was actually belt slip!

[Cyker]

The tricky bit that people miss is the epicyclic bit isn't what gives it the gear ratios - As you say it's just used like a differential to connect MG1, MG2 and the ICE together - MG1 is the secret sauce, so to speak, that simulates the infinite ratios.

[FROSTYBALLS]

Moved to General Discussions

[MikeSh]

1 hour ago, Chas G said:

@MikeSh i watched a video of someone explaining the Toyota hybrid system and I must admit that I would have had to make notes and watch it many times before I would grasp more than the general principles. As he was talking he was dismantling a transaxle and it had an incredible number of component parts.

Probably one of the WeberAuto videos I'd guess.

I think if you saw a dismantling of a conventional auto, or even a manual box, you'd need something much bigger than "incredible" to describe the number of bits. And quite a few of those are wearing parts like clutches, actuators and (in a manual) syncromesh.

[Fangz]

I like this explainer video.

 

And yeah the eCVT on a hybrid is completely different from a CVT and avoids most of the problems.

 

 

[Mjolinor]

I am sure this has been pasted somewhere on here before but maybe not so here it is:

http://eahart.com/prius/psd/

It is without doubt the best explanation of the way the Prius does it.

Nice animation.

[Cyker]

One fun thing with the HSD is it's the only multi-ratio 'gearbox' I know of that doesn't rely on friction to transmit torque to the wheels - The whole system is completely interlocked with gears and at no point can any part of it turn independently of the rest. Every other kind of multi-ratio gearbox relies on friction in some way - CVT (Belts), MMT and DSG (Clutches), Torque Converter (Fluid).

The HSD is really quite ingenious, and whoever came up with using it like this doesn't get enough credit!

[MikeSh]

11 minutes ago, Cyker said:

Torque Converter (Fluid).

Strictly that's not a friction drive but there are losses from friction as the fluid moves.

The HSD is partly an electro-magnetichere drive and there will be some losses in the fields and wires that sort of correspond to the fluid losses, but much smaller of course.

[Mjolinor]

That animation is one of the reasons I bought a Prius years ago. It is without doubt the best method of drive available in my opinion.

As I am not that familiar with the modern way of doing things I do wonder if it is still used universally in Toyota hybrids and do any other manufacturers use it or is it still a Toyota only patent?

The original patents must be expired or due to expire by now I would think.

 

 

[MikeSh]

4 minutes ago, Mjolinor said:

The original patents must be expired or due to expire by now I would think.

Not sure about the worldwide situation but I think patents are (or were) 20 years. In that case this must have expired some 5 years or more ago since the Prius appeared in 1997.

At that stage the advent of EVs was well under way, so other manufacturers may have decided it wasn't worth developing their own version of it just for a few years sales.

[Mjolinor]

Patents are twenty years but can be extended by "improvements" later than the original filing date.

They really are a proper stupid invention that favours the big boys because defending them is horrendously expensive and the small guy does not stand a chance of fighting against someone that can just throw money at it and wait for you to die of old age.

I have defended a couple of patents and it has to be the most ridiculous, boring pastime in the world explaining things to people that do not understand and having them make decision as to whether you are right or not.

[Cyker]

I think some other manufacturers use it under license from Toyota, e.g. Ford, but the rest of the manufacturers making full/plug-in hybrids tend to use either a series (Effectively a range extended EV, electrics drive the wheels, engine charges Battery and powers electric motor e.g. the Jazz and i3 REx) or parallel (engine drives one set of wheels, electrics drive the other, e.g. Golf, hyundai hybrids, i8,) set up.

To my knowledge, only Toyota make a series/parallel hybrid drivetrain (i.e. it can function as either or both!)