2016 GS 6 speed transmission
11-24-15, 08:01 AM
#31
"electronic continuously variable transmission" usually refers to the planetary gear transmission used in Toyota and Ford hybrid cars.
More precisely the eCVT transmission is a Power Split Device transmission, using just one single planetary differential gearset to combine the power from two electric motors and one gasoline engine.
How the eCVT works: http://www.eahart.com/prius/psd
It is an excellent transmission system because mechanically it is so simple. One single planetary gearset, no gear-shifting wear-and-tear, no clutch, no hot-running torque converter, no regular-CVT friction belts.
Unlike a regular-car multispeed gear-shifting transmission that has over 100 moving parts, the PSD transmission in the Prius has all of 22 moving parts. Less moving parts = less potential failure points = lower maintenance.
The other chief advantage of the PSD transmission is that the electric motor can be used to brake the car (convert the car's forward momentum into storable electricity), which saves brake pad wear tremendously. That is why PSD cars like the Prius do not need brake pad changes until well after 100,000 miles (not a typo).
Cars that use the eCVT/PSD transmission:
- Toyota Prius, Camry Hybrid, Highlander Hybrid
- Ford Escape Hybrid, Fusion Hybrid
- Nissan Altima Hybrid
- Lexus Hybrids.
The eCVT is not to be confused with a regular CVT, which uses a friction belt driven by two pulley wheels that change their diameter on the fly. Honda's hybrids use the belt-and-pulley CVTs.
More precisely the eCVT transmission is a Power Split Device transmission, using just one single planetary differential gearset to combine the power from two electric motors and one gasoline engine.
How the eCVT works: http://www.eahart.com/prius/psd
It is an excellent transmission system because mechanically it is so simple. One single planetary gearset, no gear-shifting wear-and-tear, no clutch, no hot-running torque converter, no regular-CVT friction belts.
Unlike a regular-car multispeed gear-shifting transmission that has over 100 moving parts, the PSD transmission in the Prius has all of 22 moving parts. Less moving parts = less potential failure points = lower maintenance.
The other chief advantage of the PSD transmission is that the electric motor can be used to brake the car (convert the car's forward momentum into storable electricity), which saves brake pad wear tremendously. That is why PSD cars like the Prius do not need brake pad changes until well after 100,000 miles (not a typo).
Cars that use the eCVT/PSD transmission:
- Toyota Prius, Camry Hybrid, Highlander Hybrid
- Ford Escape Hybrid, Fusion Hybrid
- Nissan Altima Hybrid
- Lexus Hybrids.
The eCVT is not to be confused with a regular CVT, which uses a friction belt driven by two pulley wheels that change their diameter on the fly. Honda's hybrids use the belt-and-pulley CVTs.
Hope this helps,
~ Im2bz2p345
Btw - as someone who owns the 4GS hybrid & driven both the GS350 a countless number of times, in manual mode the 13' GS hybrid 6 speed behaves almost identical to the 6 speed in the 13' GS350. But my original comment was comparing a 13' GS350 and 14' GS350 as I've test driven both of those vehicles.
11-24-15, 08:34 AM
#32
Now I understand.
Amazing this eCVT twin planetary gear system for gasoline-electric hybrids only.
http://www.eahart.com/prius/psd/
.
Amazing this eCVT twin planetary gear system for gasoline-electric hybrids only.
http://www.eahart.com/prius/psd/
.
Last edited by peteharvey; 11-24-15 at 02:43 PM.
11-24-15, 08:42 AM
#33
Lexus Fanatic
2016 GS 6 speed transmission
Reviews of the GS450h don't agree that the CVT and the 6 speed behave the same. Perhaps in manual mode, but in normal driving I'm sure the CVT feels like a CVT.
11-24-15, 12:55 PM
#34
11-24-15, 01:14 PM
#35
Lexus Fanatic
In one video review of the GS450h you can actually hear that drone during the review, I will try and find it. Just not my thing.
11-24-15, 01:38 PM
#36
I have driven the GS450h 1st and 2nd gen a number of times, but I still don't completely understand if this eCVT with twin planetary gears delivers truly continuous gear ratios between two set points?
When I drive, I certainly can't feel any gear changes.
I still don't exactly understand how the planetary gears gives a continuous gear ratios?
In the old days, I thought we had to have a pulley with a V-groove and a belt for a CVT, and as the plates came together, the belt got extruded out of the pulley to mimic a larger gear.
If the eCVT with twin planetary gears really did give genuinely continuous gear ratios, then it is a major breakthrough, so why didn't I know about it?
Can this eCVT be used in conventional gasoline engines?
When I drive, I certainly can't feel any gear changes.
I still don't exactly understand how the planetary gears gives a continuous gear ratios?
In the old days, I thought we had to have a pulley with a V-groove and a belt for a CVT, and as the plates came together, the belt got extruded out of the pulley to mimic a larger gear.
If the eCVT with twin planetary gears really did give genuinely continuous gear ratios, then it is a major breakthrough, so why didn't I know about it?
Can this eCVT be used in conventional gasoline engines?
11-24-15, 02:03 PM
#37
Lexus Fanatic
I still hate the way they drive.
Can this eCVT be used in conventional gasoline engines?
11-24-15, 02:46 PM
#38
Better explanation of how eCVT works here:
http://john1701a.com/prius/documents...lit-Device.pdf
From now on, I'll call conventional CVT's "cone & belt drive", while power split device eCVT as "planetary drive".
Does this mean that the GS450h has only one electric motor, and that motor is located adjacent to the gearbox, rather than having two motors powering the rear wheels directly?
.
http://john1701a.com/prius/documents...lit-Device.pdf
From now on, I'll call conventional CVT's "cone & belt drive", while power split device eCVT as "planetary drive".
Does this mean that the GS450h has only one electric motor, and that motor is located adjacent to the gearbox, rather than having two motors powering the rear wheels directly?
.
Last edited by peteharvey; 11-24-15 at 02:49 PM.
11-25-15, 08:28 AM
#39
Better explanation of how eCVT works here:
http://john1701a.com/prius/documents...lit-Device.pdf
From now on, I'll call conventional CVT's "cone & belt drive", while power split device eCVT as "planetary drive".
Does this mean that the GS450h has only one electric motor, and that motor is located adjacent to the gearbox, rather than having two motors powering the rear wheels directly?
http://john1701a.com/prius/documents...lit-Device.pdf
From now on, I'll call conventional CVT's "cone & belt drive", while power split device eCVT as "planetary drive".
Does this mean that the GS450h has only one electric motor, and that motor is located adjacent to the gearbox, rather than having two motors powering the rear wheels directly?
According to the GS450h specs, there are two eletric motors:
Motor Generator 1 (MG1) - Function: Primary generator, engine starter, controls engine speed. Produces a maximum output of 180 hp (134 Kw).
Motor Generator 2 (MG2) - Function: Drives rear wheels; regenerative braking. Produces a maximum out of 200 hp (147 Kw).
I am not honestly not a subject matter expert, but this is a good topic that you may interested in: https://www.clublexus.com/forums/hyb...ary-gears.html
I threw in some videos in that topic that go over technicalities if you're interested.
~ Im2bz2p345
Last edited by Im2bz2p345; 11-25-15 at 06:26 PM.
11-25-15, 11:06 AM
#40
Yes, two sets of planetary gears can give four different discrete conventional gear ratios, but it is very difficult to understand how the eCVT actually gives a continuous/infinite set of gear ratios between two different limits.
I'm beginning to suspect that the eCVT gives a continuous/infinite set of gear ratios by being driven at different relative speeds by one/two electric motors, but I'm not sure if those are just small gearbox electric motors, or big electric motors used to actually drive the gasoline-electric hybrid car?
.
Last edited by peteharvey; 11-25-15 at 06:30 PM.
11-25-15, 06:19 PM
#41
Lexus Fanatic
How the HSD system works is fascinating. I remember when we had the Prius and I used to post on PriusChat people would post diagrams and all. Very cool.
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