gorcorps

I'm just curious. I've had a CVT before and really enjoyed it. Not having that jerking feeling of shifting gears was one of the perks of a CVT. Now I read that companies are starting to program their CVTs to have these "gears" programmed in the CVT to mimic that same feeling.


I'm curious how the CVT works in the 450h. Is it one smooth gear like it should be, or do you have the deal with a fake jerk in the transmission as you "shift gears"?

kitlz

The 450h is seamless. There is the ability to upshift and downshift if you want. So best of both worlds IMO.

gorcorps

That's good to know. I saw something about being able to upshift and downshift which prompted my question in the first place. If those same "gears" aren't present during normal, everyday driving then I'll be happy.


Thanks

TexasRxh

You may have read about the paddle shifters on the F-Sport models...not sure if the Rxh even has those.

Anita?

kitlz

My 450h F-Sport has the paddle shifters in addition to sequential shifting. Haven't used either yet. I'm still trying to get used to the gas pedal sensitivity. It's much more responsive than the '10 and that's with eco mode on, LOL!

ericsan13

I can also confirm that my F-Sport 450h has paddle shifters. I too have not touched them yet!

No clue what they are for though...my guess is that it increases engine output to simulate gearing. But wouldn't stepping on the gas pedal have the same effect??

gorcorps

The paddle shifters are still changing your gear ratio like with any other transmission, the difference is that the gear ratios in a CVT aren't fixed during normal driving. They programmed set gear ratios into the computer for paddle shifting so that it acts like a traditional transmission, but it doesn't do anything to your engine output like stepping on the gas would.


For anyone curious about how CVTs work, there are a lot of good explanations out there:


It's pretty cool technology

ericsan13

I am not sure this video may be applicable as this is not a conventional conical CVT. The RX450h uses the same system as the Prius, and hence uses a power split device:
http://eahart.com/prius/psd/

If you take a look at the interactive diagram, how can the paddle shifting be explained?

gorcorps

You're right, I was stuck on traditional CVTs but since this is a hybrid (and a Lexus at that) it's different. Instead of changing the diameter of the pulleys involved, the eCVT uses two electric motors to perform basically the same function. I'll have to dig a little more to get into specifics, but to simulate gear settings (using the paddle shifters) it would basically be computer controlled ratios of how much the electric motor assists in propelling the car in addition to the engine.


In normal driving the computer calculates in real time how much power to get from the electric motors to keep the engine running at as efficient of speed as possible at that time. I imagine by "changing gears" using the paddle shifter you're just forcing the computer to use the gas engine to do more or less work. It won't be as efficient as just letting the computer do its thing, but you can have a little more fun driving this way as you have some control over how the motor and engine interacts.

ericsan13

Bingo, this is exactly what I was assuming. I have not heard an official answer though.

My guess is that down"shifting" will just tell the car to use more gas engine power. Upshifting will make the car use less engine power. But then both of these are almost pointless since the same can be accomplished by just using the gas pedal?

gorcorps

Ah, now I see what you mean in the first post I replied to with the video. My bad...


I guess the only difference is with the gas pedal you're also trying to adjust your speed. If you didn't want to also accelerate then you could set the cruise control, then with the paddle shifters (theoretically) shift in one direction or the other to change the balance between the ICE and electric motor. Still, I think we're both at the same conclusion that it's not really useful and most people won't bother at all.


I'm also trying to think through low gears vs. high gears. Wouldn't low gears be mostly (if not all) electric? Then you get more and more power from the ICE as you shift up, until you're fully using the engine with little or no electric power (like at highway speeds).

ericsan13

I never thought about it that way. In a normal car, downshifting normally produces higher RPMs and thus more engine power. Shifting up would lower engine RPMs.

But in a hybrid, did Lexus design the paddles to mimic a normal car? Or does it have the reverse effect that you mentioned?

My guess is that the paddle shfiters modulate the gas engine response. I should probably figure this out by using the paddle shifters.

Zift01

Fake gear I use for engine braking on a downhill. You can not do it with gas pedal. Using brakes for long period of time is bboarding.
RMF (read manual...) :-**

ggebhardt

The paddles only change the engine rpm. The higher rpm make more power instantly available to the driver, just like a regular tranny.