CVT with shift sensation

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This defeats the purpose of the CVT, which is programmed to keep the engine at its optimal power band. Each shift reduces the benefit. Either get an automatic or a stick if you want shift sensation.
 
Originally Posted By: gregoron
Either get an automatic or a stick if you want shift sensation.


The point is that CVTs are increasingly replacing automatics altogether, and the customer has no choice but the CVT. The nice part about it is if they want the smooth feel of the CVT, they can have it. If they want the feel of a stepped transmission, they can have it. Flexibility is great.
 
How many shift points does it have? None going up, and six going down? 8 going up, and 9 going down? Not only that, but nothing says it has to be the same "ratio" at each point. It could decide to make a step this time and do a slide next time.

I think the rubber band effect would drive me nuts. Lately I've been wondering how people managed before lockup torque convertors. The two hundred rpm "rubber" effect I can hear when it's unlocked bugs me. I could imagine a 1,000rpm effect or more.

Then again, I prefer an engine to lug down and just torque its way out of something.

I am pretty sure I've asked this in the past, but never gotten a good answer: what would manual control of a CVT look like? On an automatic it's pretty easy: up/down manual selection of the fixed gear ratios. On a CVT, would it just be a slide switch? Seems like manually fixed ratios would be required on a CVT--otherwise, one could not have manual control.
 
Originally Posted By: Hokiefyd
The point is that CVTs are increasingly replacing automatics altogether, and the customer has no choice but the CVT. The nice part about it is if they want the smooth feel of the CVT, they can have it. If they want the feel of a stepped transmission, they can have it. Flexibility is great.

Increased choice is a good thing only if the additional options are worthwhile. If I could only have toast for breakfast, adding eggs to the menu would be a meaningful increase in choice. Adding cyanide tablets wouldn't be.

"The feel of a stepped transmission" is three things:

1. Shift shock
2. Interruption in power delivery
3. The engine falling in and out of the optimal RPM range for whatever you're trying to do

In other words, all bad things.

I put up with all of those things in my car because it's manual, which means my toleration buys me a measure of control that I couldn't get otherwise. What is the argument for putting up with -- let alone WANTING -- those bad things in an automatic?

So far, all people have said is that stepless transmissions make the car feel broken. Everyone seems to understand that they only feel that way because they're used to "the feel of a stepped transmission." In other words, it's just habit. Why is nobody thinking "maybe I should look at it differently?"
 
Originally Posted By: d00df00d
"The feel of a stepped transmission" is three things:

1. Shift shock
2. Interruption in power delivery
3. The engine falling in and out of the optimal RPM range for whatever you're trying to do

In other words, all bad things.


I do agree that they made the package less efficient. If efficiency is your only metric, then sure, they're all "bad".

Life isn't always so black-and-white. I like to hear the engine rev up "through the gears". I like to feel the engine as it climbs through its power curve. I like to listen to the change in tone as it steadily increases in speed. I like to be able to load the engine down in a gear and not have it flare up in speed if I know that the load is temporary (like climbing a short hill or momentarily increasing my speed).

Variable ratios are boring to me. They further isolate the driver from the actions, from the feel, of the powertrain. I don't want that isolation. I want to feel it work. I want to hear it work. I actually LIKE that about stepped transmissions. I don't have manual transmissions in our vehicles for a few reasons, but it doesn't mean that I want to miss that feeling, that sensation, of a good engine/transmission combo going about its business.

I fully know that variable ratios are more efficient. I fully know that variable ratios enable better performance. That doesn't matter to me. If getting that last 1/10th of an MPG or that last 1 MPH in the 1320 means having to put up with a limp-feeling powertrain all the time, then I don't want it.

I don't have a problem with the mechanicals of a CVT. I like simple. I like easy. As a CVT owner, I would want to have a "D" mode where it would do its thing just like any other CVT. If I'm shuttling co-workers to lunch, or if my wife is driving the car, or if I'm just in the mood for quiet and smooth, "D" works. But I also want an "M" mode with paddle shifters so that I can work it up and down "through the gears" if I want to hear and feel the powertrain work. CVTs don't hold the engine for engine braking down hills or for switching back and forth on twisty roads. Sometimes that's what I want to do. Some may not want that, and that's cool; "D" is for them. Including an "M" mode costs very little and adds a huge degree of flexibility while still using the same equipment.
 
I suspect they're doing this because of customers who don't know anything about the transmission or what they bought.

I'm guessing Nissan is trying to avoid dealer warranty trips and bad surveys (J.D. Power, etc) from owners who say "it's not working right, it won't shift."

EDIT- I just read the article and it appears this is probably the main thing driving this update.
 
Bizarre. Employ a new technology just to defeat it.

About abnormal wear, I'd hope any self-respecting engineer would use some type of wear leveling logic in their pre-defined steps,ie alternating between say a 1.35 and a 1.28 (eg) 'virtual third gear' or whatever.
 
C'mon guys. Shift shock? Whazzat? No modern automatic trans has any. Retarded timing and throttle reduction are precisely timed in many cars so you don't feel nuttin' unless you got your foot in it.

And the whole advantage of a slushbox, as well as the reason most of them are much quicker at the strip than their identical manual transmission variants, is there is NO interruption of the power delivery, none at all.

Moving cams has widened powerbands so far that many engines have a table flat torque curve, this pretty much means you are always in the 'optimal' rev range as well.

Next I am waiting to hear someone try again to tell us that CVT's have no wear in normal use!
 
I looked at some videos of cvt that goes through shifts. I noticed the rpm drops but not sure if it's a real or fake drop.

Does the transmission pause the movement of the belt for that split moment or it disconnect engine and transmission like a clutch?

Maybe these cvt 2.0 will require more frequent fluid changes?
 
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Originally Posted By: wing0
I looked at some videos of cvt that goes through shifts. I noticed the rpm drops but not sure if it's a real or fake drop.

Does the transmission pause the movement of the belt for that split moment or it disconnect engine and transmission like a clutch?

Maybe these cvt 2.0 will require more frequent fluid changes?


The whole advantage of the CVT is continuously variable ratios. There is no interruption of power flow, only torque reduction in many applications to protect the unit itself...
 
Originally Posted By: Hokiefyd
Originally Posted By: gregoron
Either get an automatic or a stick if you want shift sensation.


The point is that CVTs are increasingly replacing automatics altogether, and the customer has no choice but the CVT. The nice part about it is if they want the smooth feel of the CVT, they can have it. If they want the feel of a stepped transmission, they can have it. Flexibility is great.


I hear ya, but what about durability and longevity? As long as there's a market for Pickups and larger SUV's for people who tow, I think the "traditional automatic" transmission will be around until they can beef up the CVT.
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Which is probably one reason ZF is making 8 and 9 speed units and pushing for more gears.
 
Originally Posted By: Hokiefyd
Variable ratios are boring to me. They further isolate the driver from the actions, from the feel, of the powertrain. I don't want that isolation. I want to feel it work. I want to hear it work. I actually LIKE that about stepped transmissions. I don't have manual transmissions in our vehicles for a few reasons, but it doesn't mean that I want to miss that feeling, that sensation, of a good engine/transmission combo going about its business.

The stepless feeling with a CVT IS the sensation of an engine/transmission combo going about its business. You're no more isolated from that than you are from the workings of a normal automatic.


Originally Posted By: Hokiefyd
I don't have a problem with the mechanicals of a CVT. I like simple. I like easy. As a CVT owner, I would want to have a "D" mode where it would do its thing just like any other CVT. If I'm shuttling co-workers to lunch, or if my wife is driving the car, or if I'm just in the mood for quiet and smooth, "D" works. But I also want an "M" mode with paddle shifters so that I can work it up and down "through the gears" if I want to hear and feel the powertrain work.

Again, the steplessness IS the sound and feeling of the powertrain working. I'm still not sure what you're talking about here.

I dislike the feeling and sound of a CVT, too. But I dislike the feeling of automatics by definition, so...
 
Originally Posted By: d00df00d
Again, the steplessness IS the sound and feeling of the powertrain working.


It's really not. With a stepless transmission, you push the accelerator and the engine revs up to a point where the software believes the engine provides the best combination of power and efficiency, and it continually varies the ratios to keep the engine there. It drones. It's a constant HUMMMMMMMM as the car accelerates forward. Smooth for sure. But it sounds like a constant speed vacuum cleaner. Or a boat. Or a go kart with a centrifugal clutch. There's very little change in the way the powertrain sounds. I don't like that. It's boring; it's monotonous. It's drab. Stepped ratios provide different sounds and feels from the powertrain.

And then on the other hand, where you might WANT a constant engine speed (like to hold a gear through twisty corners), a conventional CVT without step control can't offer that. If you're on and off the throttle, that CVT is going to cycle the engine up and down and not keep the engine cooking where you want it to. CVTs offer no control; with a stepped transmission, automatic or otherwise, the driver has full control over the engine.

I like control over the engine, as apparently you do. Because of a foot injury my wife sustained years ago, a clutch pedal in our cars is out. What's the next best thing? The ability for me to control engine speed through ratio selection. Stepless CVTs don't offer that, and I'm not interested in them for that reason. Give me ratio control with a CVT, even if it's a separate "M" mode or something, and I'd be happy with it.
 
Originally Posted By: demarpaint
I hear ya, but what about durability and longevity?


Don't get me wrong; I'm not promoting CVTs. I'm saying that if my only choice in "automatic" transmission in a vehicle is a CVT, then I would like the ability to control it to some degree. Paddle shifters would be fine.

In the CVTs I've driven to date, the driver has ZERO control over what's going on. At least with a stepped automatic, you can dictate engine speed through gear selection.
 
Originally Posted By: SteveSRT8
C'mon guys. Shift shock? Whazzat? No modern automatic trans has any. Retarded timing and throttle reduction are precisely timed in many cars so you don't feel nuttin' unless you got your foot in it.


My 4 year old truck definately has shifts that can be felt. I won't say neck snapping but you know they occur.

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I still haven't heard of a good answer to my question: how would you have manual control over a CVT otherwise?
 
Originally Posted By: supton

I still haven't heard of a good answer to my question: how would you have manual control over a CVT otherwise?


I'll take a stab at that one.

Essentially, in order to have a full control over a CVT transmission, you would need a sliding lever, sort of like a dimmer. The ends of the lever's movements would represent the highest and lowest gear ratios and everything in between would be dictated by lever position.
The problem with this approach would be the need to constantly adjust the lever and the gas pedal position. Since there would be no gates, one would have to smoothly slide the lever back and forth to adjust the speed. That would be a major headache even for enthusiasts.
This is why the stepped CVTs are being implemented for those wanting to have some sort of manual control.
 
Personally I think it's a great idea. Think about this: you could program it to have say 5% steps in "race" mode. In "fun" mode you could have say 10% steps while accelerating, and say 20% downshifts--that way, it accelerates reasonably well, loaf along in a high gear--then with a click or two be deeply geared for passing. Without having to hit down ten times.

Imagine that: with a bit of software work, you could have as many (or few) gears as you wanted. And then when you aren't in the mode, set it to CVT mode. And then change your mind next week and redo it.
 
Having driven a few of them, I am doubtful that anyone consulted a BSFC chart for the engines.

The Nissans either lug the engine too much or have it running at redline all the time.

Seems like it would be possible to program in the BSFC chart and have it set the RPM according to throttle input (ie - low throttle, I don't want to accelerate fast, medium throttle - put it where it has the most volumetric efficiency , full throttle - best torque ,horsepower).
 
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