E-CVT and rear hatch queries

[Pannett]

I'm trying to understand how the eCVT works. Am I correct in thinking that MG1 acts as a starter and charges the Battery whilst MG2 provides power to drive the car as well as providing recharging power to the Battery on braking, so there is no CVT belt with cones to 'change' gear? How does the powered rear hatch work? Is there a helical gear drive in the struts?

[Cyker]

There are a lot of videos on YouTube that explain this better, but essentially yes - The main function of MG2 is to turn the wheels and provide regen braking, while MG1 mediates power and torque flow from the engine to the wheels/MG2 (They're linked), but also acts as a generator and a starter for the engine. It can also act to  'bump start' the engine if the car is already moving

[flash22]

The e-cvt's from mid 2000 on are direct drive - no belts, cones or chains, they are more akin to a manual gearbox

https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive

the rear power hatch struts are usually linear actuators based on a screw, limit switches and rotary encoders - way more reliable and cost-effective than a hydraulic system

[Pannett]

Thank you for your prompt replies.

[Pannett]

I thought I understood how the eCVT works. However, if I use the paddles to change gear, a number appears in the dashboard display implying I've changed down or up. Without belts and cones, how does this work?

[Cyker]

Same way it does it in a normal belt-and-cone CVT - It fakes it.

 

[VanHiggy]

🤣

[sportse]

2 hours ago, Cyker said:

Same way it does it in a normal belt-and-cone CVT - It fakes it.

 

I had a 21 Honda jazz hybrid, which has no physical connection at all between engine generator and electric motor driving the wheels when accelerating… yet they have added ‘gear changes’ by programming it to make noise as though it was changing gears.

it did break up the mooing, but not needed now as the facelift corollas have very little mooing unless you use a lot of accelerator pedal. 

[Pannett]

Thanks for the replies. In practice I let the engine management system sort out the 'gear changes' but was wondering about the manual override and how it worked. Now I know.

[Obsidian Estate]

I think I've "changed gear" in my Corolla once in over 2 years.

[Chainbreaker]

On 3/10/2024 at 7:42 PM, flash22 said:

The e-cvt's from mid 2000 on are direct drive - no belts, cones or chains, they are more akin to a manual gearbox

https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive

the rear power hatch struts are usually linear actuators based on a screw, limit switches and rotary encoders - way more reliable and cost-effective than a hydraulic system

Ecvts don't really have much in common with a manual gearbox I'm afraid - no synchromesh, clutches or input/output shafts. The power split device uses planetary gears which is arguably more akin to a traditional torque converter auto, but this case only has a single gear.

https://mag.lexus.co.uk/perfect-partners-e-cvt-and-hybrid/

Technicalities aside, the eCVT is a simple yet brilliant piece of automotive engineering and doesn't get nearly as much credit as it should get. Smooth, efficient and reliable since there are no belts/clutches/selectors/mechatronics to go wrong. 

[flash22]

more akin to a manual gearbox (as in a metal container that houses gears) rather than a pressurised system with a TC or a belt and pulley like the Jatco grenade

[AndrueC]

On 3/12/2024 at 10:05 PM, sportse said:

I had a 21 Honda jazz hybrid, which has no physical connection at all between engine generator and electric motor driving the wheels when accelerating… yet they have added ‘gear changes’ by programming it to make noise as though it was changing gears.

it did break up the mooing, but not needed now as the facelift corollas have very little mooing unless you use a lot of accelerator pedal. 

Yes they added that on the last all-petrol version. I was in two minds about that change when I had a curtesy car. On the one hand it irked me that Honda had felt the need to emulate the (inefficient and power wasting) gear change sound just to please the ignorant on the other hand it seemed to be a purely auditory effect.

As far as I could tell the power was still being delivered smoothly just as it was on my older Jazz. One change I did like though was that they'd smoothed out the transition between Atkinson and Otto cycles.

My Jazz was the first to have that feature and it could be a bit lumpy climbing gentle hills (almost like old fashioned automatic hunting) and pulling away from roundabouts could be painful if you weren't forceful enough with the accelerator to 'kick down' into Otto cycle. That transition was fixed in the later versions.