Like to learn more about the CVT in the 450h
07-20-17, 08:36 AM
#1
Pole Position
Thread Starter
Like to learn more about the CVT in the 450h
Does anyone have a site that will graphically show how the CVT works.
Are there parts that will wear out and need servicing. Notice there is not a point where the CVT seems to lock up to the motor RPM like a regular automatic tranny.
Just lots of questions, could not be more happy with the performance.
Are there parts that will wear out and need servicing. Notice there is not a point where the CVT seems to lock up to the motor RPM like a regular automatic tranny.
Just lots of questions, could not be more happy with the performance.
07-20-17, 02:21 PM
#2
Right here:
http://eahart.com/prius/psd/
The PSD is classified at an e-CVT and is at the heart of all toyota and lexus hybrids.
http://eahart.com/prius/psd/
The PSD is classified at an e-CVT and is at the heart of all toyota and lexus hybrids.
07-20-17, 02:27 PM
#3
Pole Position
Thread Starter
I have seen some YouTube videos on the Toyota CVT and it uses a belt between two pullies that change diameter by opening and closing with a belt. I understand the principle. What is the belt made of and does it ever need replacement. Seems like this would be a high wear item.
07-20-17, 02:31 PM
#4
I don't think there are any belts. Maybe in older priuses, but that would've been a chain, not a belt.
07-21-17, 08:56 AM
#5
Pole Position
Thread Starter
I believe you are right from this image. It would still have to take a lot wear
07-21-17, 10:24 AM
#6
Chains are supposed to be for the lifetime of the car. The regular 350 uses a chain and I haven't heard of anyone needing to replace it yet...but I have no idea how this chain differs.
07-21-17, 02:27 PM
#7
Pole Position
Thread Starter
Well what ever, I love both of my 450h units. My poor LX stays in the garage most days now.
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07-22-17, 10:05 AM
#8
Driver School Candidate
So Toyota does have some CVTs, like in the Corolla, but the e-CVT is really only called that since it feels like a CVT when you drive it. You'd probably really enjoy the video I've attached below. He knows his stuff and does a good job explaining it. They're long videos but worth a watch for sure. That video in the link shows a P112 from the Prius, our front transaxle is a P313 (here's a schematic from the repair manual) but it's pretty similar.
07-22-17, 11:19 AM
#9
Toyota/Lexus CVT's use planetary gears not the adjustable pulley system.
07-22-17, 11:59 AM
#10
Pole Position
Thread Starter
07-22-17, 02:00 PM
#11
Driver School Candidate
07-24-17, 08:11 AM
#12
Pole Position
Thread Starter
Still I do not understand what makes the hybrid transaxle variable like what the standard CVT does. The hybrid transaxle does look like it would be more robust with less parts to wear.
08-18-17, 11:45 AM
#13
It took me a while to wrap my head around this, too.
A conventional CVT allows for the input shaft and output shafts to rotate a different speeds so that the engine can spin fast enough to create adequate horsepower even when the vehicle is moving slowly. Some sort of control mechanism tells the splined cones on the two shafts to move in or out in order to change the ratio between them.
The Toyota/Lexus eCVT doesn't use a belt of splined cones at all. Instead, it uses a straightforward planetary gearset, similar to the one in a differential on the rear axle on conventional cars. One shaft goes to the engine, one goes to a motor, and the third is the output. The engine and motor can work completely independently to spin the output. The motor can also spin in the reverse direction. The computer tells the motor how to spin at that moment such that the engine can rev up to whatever rpm is needed to satisfy the throttle. So if you're moving slowly but you put your foot into the accelerator the computer tells the motor to spin backwards at high speed so that the engine can rev at high rpms and produce a lot of power.
There are many YouTube videos showing the complex interactions between components. Fascinating to watch.
So, no, here are no CVT belts and cones in the Toyota system. Just engine, electric motors, and a lot of computer smarts.
A conventional CVT allows for the input shaft and output shafts to rotate a different speeds so that the engine can spin fast enough to create adequate horsepower even when the vehicle is moving slowly. Some sort of control mechanism tells the splined cones on the two shafts to move in or out in order to change the ratio between them.
The Toyota/Lexus eCVT doesn't use a belt of splined cones at all. Instead, it uses a straightforward planetary gearset, similar to the one in a differential on the rear axle on conventional cars. One shaft goes to the engine, one goes to a motor, and the third is the output. The engine and motor can work completely independently to spin the output. The motor can also spin in the reverse direction. The computer tells the motor how to spin at that moment such that the engine can rev up to whatever rpm is needed to satisfy the throttle. So if you're moving slowly but you put your foot into the accelerator the computer tells the motor to spin backwards at high speed so that the engine can rev at high rpms and produce a lot of power.
There are many YouTube videos showing the complex interactions between components. Fascinating to watch.
So, no, here are no CVT belts and cones in the Toyota system. Just engine, electric motors, and a lot of computer smarts.
08-18-17, 12:45 PM
#14
Pole Position
Thread Starter
It took me a while to wrap my head around this, too.
A conventional CVT allows for the input shaft and output shafts to rotate a different speeds so that the engine can spin fast enough to create adequate horsepower even when the vehicle is moving slowly. Some sort of control mechanism tells the splined cones on the two shafts to move in or out in order to change the ratio between them.
The Toyota/Lexus eCVT doesn't use a belt of splined cones at all. Instead, it uses a straightforward planetary gearset, similar to the one in a differential on the rear axle on conventional cars. One shaft goes to the engine, one goes to a motor, and the third is the output. The engine and motor can work completely independently to spin the output. The motor can also spin in the reverse direction. The computer tells the motor how to spin at that moment such that the engine can rev up to whatever rpm is needed to satisfy the throttle. So if you're moving slowly but you put your foot into the accelerator the computer tells the motor to spin backwards at high speed so that the engine can rev at high rpms and produce a lot of power.
There are many YouTube videos showing the complex interactions between components. Fascinating to watch.
So, no, here are no CVT belts and cones in the Toyota system. Just engine, electric motors, and a lot of computer smarts.
A conventional CVT allows for the input shaft and output shafts to rotate a different speeds so that the engine can spin fast enough to create adequate horsepower even when the vehicle is moving slowly. Some sort of control mechanism tells the splined cones on the two shafts to move in or out in order to change the ratio between them.
The Toyota/Lexus eCVT doesn't use a belt of splined cones at all. Instead, it uses a straightforward planetary gearset, similar to the one in a differential on the rear axle on conventional cars. One shaft goes to the engine, one goes to a motor, and the third is the output. The engine and motor can work completely independently to spin the output. The motor can also spin in the reverse direction. The computer tells the motor how to spin at that moment such that the engine can rev up to whatever rpm is needed to satisfy the throttle. So if you're moving slowly but you put your foot into the accelerator the computer tells the motor to spin backwards at high speed so that the engine can rev at high rpms and produce a lot of power.
There are many YouTube videos showing the complex interactions between components. Fascinating to watch.
So, no, here are no CVT belts and cones in the Toyota system. Just engine, electric motors, and a lot of computer smarts.
It works VERY well in my opinion delivering smooth power. When you punch it the electric motor kick in nicely.
Feeling better about longevity but do not keep my vehicle that long anyway.
If I had to do it again I would stick with the 450 just because of smooth extra power.
08-18-17, 01:05 PM
#15
Lead Lap
Check out http://ae.pwr.wroc.pl/filez/20110606...HEV_Toyota.pdf , but don't let the chain throw you, as the early Prius (you do know that your RXh is a Prius on steroids, don't you?) eCVTs had a chain - which has been replaced with a gear in all eCVTs currently produced by Toyota/Lexus.
Think of the eCVT as an electrically-managed CVT - so designated as to allow for advertisement as the familiar CVT-like gear-change-less transmission; and to seem (to the driver) to function like a CVT as opposed to a multi-speed (gear) transmission.
There are no wear items (clutches, bands, cones, belts, etc) in the eCVT, as it is a planetary similar to the gears in the more "Normal" transmissions until the end of the last century - I'm qualifying that time frame to keep out the Dual Clutch Automatic Transmissions (DCT) in vogue today (think of DCT's as formerly-manual transmissions with the addition of computer-electric-motor-shifted and slave-operated wet or dry clutches). Those former "Normal" auto trannies used a planetary gear set for two speeds; and each planetary gear set provided two speeds.
Like you, I was prejudiced against a pulley-and-belt CVT when shopping for cars; however after a thorough investigation into the Prius' transmission and the electric air compressor I decided on the superior Toyota/Lexus 6-cylinder hybrid.
Once your head stops spinning after digesting the drivetrain of the RXh, look into the even more interesting drivetrain of the two-speed/planetary GS-450h!
Think of the eCVT as an electrically-managed CVT - so designated as to allow for advertisement as the familiar CVT-like gear-change-less transmission; and to seem (to the driver) to function like a CVT as opposed to a multi-speed (gear) transmission.
There are no wear items (clutches, bands, cones, belts, etc) in the eCVT, as it is a planetary similar to the gears in the more "Normal" transmissions until the end of the last century - I'm qualifying that time frame to keep out the Dual Clutch Automatic Transmissions (DCT) in vogue today (think of DCT's as formerly-manual transmissions with the addition of computer-electric-motor-shifted and slave-operated wet or dry clutches). Those former "Normal" auto trannies used a planetary gear set for two speeds; and each planetary gear set provided two speeds.
Like you, I was prejudiced against a pulley-and-belt CVT when shopping for cars; however after a thorough investigation into the Prius' transmission and the electric air compressor I decided on the superior Toyota/Lexus 6-cylinder hybrid.
Once your head stops spinning after digesting the drivetrain of the RXh, look into the even more interesting drivetrain of the two-speed/planetary GS-450h!
Last edited by NateJG; 08-27-17 at 03:18 AM. Reason: Error correction
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