continuously variable automatic

Honda lists it as an Electronic Continuously Variable Transmission (E-CVT). Maybe they put in automatic so people know it's not a stick shift?

 

It's too bad Honda lists the Clarity as an ecvt. That hides the fact that it is a motor driving the wheels that simply increases the motor speed to accelerate. There is no gear switching, no pauses, no shift noises, no lurching. It is a smooth increase in speed all the way from zero to maximum.

There are no belts to slip out wear out. No gear synchros to go bad.

The Clarity drive system is one step better than the Prius Synergy drive which I thought was brilliant.

 

The electronic variator in the Clarity behaves just like a belt driven variator for acceleration with the engine. The car will rev to a certain RPM depending on load and stay there through acceleration. Reliability remains to be seen, but should be good. Modern "belts" should last now too, unless they slip... they are actually metal bands.

 

I believe you are speaking of the gas engine right? Yes the gas engine runs at RPMs not associated with wheel spin. It seems to me there is no variator type action with the BEV side of the car. The whine of the electric motor (which I love hearing and hope they don't design that out in future electric cars) is locked to the speed of the car.

 

There are two electric motors, yes, the main is tied directly to the wheels, but the car has CVT action between the gas engine/generator and main motor using essentially an electric "belt" with the balance of energy going to or coming from the battery. Running with the engine on in this mode really feels just like a CVT.

 

As said above, it is not what is thought of as a conventional CVT with metal “belts” sliding between 2 opposed cones to give an infinite range of torque with engine RPMs independent of wheel rotation. I think it’s unfortunate that Honda chose to call it and eCVT as that is highly misleading to most people.
The e stands for electronic and merely means the gas engine is decoupled from the wheels by way of providing varying torque according to how much electrical power is directed to the traction motor. So like a “real” CVT, engine rpm does not necessarily match wheel rotation. And when under certain conditions the engine mechanically couples to the output shaft, there is no gearing to change. Only in this special case is there a one to one ratio of engine rpm and output rotation.
I wish Honda had put as much effort into naming their technology as they did designing it.

 

I am not a auto geek but find this discussion enlightening.

Question - Does this all mean less problems and less chance of future repairs or new technology and its associated troubles ?

 

Yes I would think so. It seems the weakest link in the chain might be the clutch which engages the connection between the gas engine and the drive train directly. that doesn't happen until the car reaches highway speeds, and it kicks in and out. Hopefully Honda knows how to make a clutch that will last.

One of the strong attractions of the Prius for me was the fact that it doesn't have gears that engage and disengage, nor does it have slippy belts. The Synergy drive was to me a very reliable transmission alternative. I think Honda has one-up'd Toyota in the Clarity design and I would be surprised if anyone reports problems with the drive train. Gas engines have become quite reliable and electric motors are even more reliable. I fully expect the Clarity to prove to be very reliable over time. We all know the startup quirks we've run into; nothing serious though.

 

Ab

Absolutely! It’s one of the best things about EV cars and is one of the reasons why traditional dealers hate them since they make most of their money off the service dept. We have no real tranny with all it’s parts or even a conventional CVT which has less parts to fail but also costs more to repair. Factor in no fan belts, no power steering pump or fluid, and a gas engine that runs much less of the time and we can reasonably expect much lower maintenance costs. However, I think your concern about the high tech and electronics is valid especially since the Clarity has no track record. That’s why I bought an extended warranty for the first time.

 

Yes. Honda simplified the drivetrain to have very few mechanical parts between the electric motor and the wheels to increase mechanical efficiency and responsiveness. In essence, they eliminated the traditional transmission gearbox. The ICE acts a generator usually but there’s a clutch that the computer may activate at higher speeds if the ICE is running already to connect it to the wheels at a fixed gear ratio if the RPMs and speed range is appropriate for better gas use efficiency (temporarily bypassing the generator to electric motor path and associated losses). No CVT. No multi speed gearbox. This is the magic of the Clarity.

 

The hybrid system in the Clarity is identical (other than ICE size) to those in the Accord, Insight, and CR-V (recently launched in Japan and Europe). Because those are always in hybrid mode, I expect the Clarity hybrid system to last far longer because most Clarity owners are in EV most of the time. For many of us, our biggest problem is making sure the gasoline in the tank doesn't go bad.

 

I think what is meant by eCVT is a virtual CVT as was commented above - something to fill in the transmission field on the brochure.
Best determination of reliability would be checking 200K mile examples with this powertain.
It is simpler in theory to have a generator and motor driving the car instead of a typical transmission.
In practice, transmissions have had much more development time and real world warranty feedback - so the jury is still out.
The expectation is that Honda put their best foot forward on the Hybrid iMMD and there will be no issues.

 

While I do not do a lot of highway driving in HV mode, the durability of this clutch does indeed seem to me to be the potential weak point in the design. During HV mode on the highway, the clutch is constantly cycling in and out as the ICE and Motor (and the combination of the two) take turns providing energy. If the system is truly sophisticated, it would start the engine and bring it up to the same RPM as the input shaft that it is going to drive. The cheap way to do it would be to simply engage the clutch and let the rotation of the input shaft provide the power to spin the engine up, but this would create a lot of wear on the clutch.

The reason I am sensitive to this is that I had an original Honda Insight (Gen 1) and the clutch wore out in 80,000 miles. This car had a CVT, but it also used a clutch for when the car came to a stop. When you pressed on the accelerator, the clutch would engage. I was pretty disappointed and angry that I was on my 3rd traction battery and had a clutch in 80,000 miles on the Gen 1 Insight and I had considered never buying another Honda again. In the end, the Transmission valve went bad and Honda would only replace the transmission ($4500).

This fact caused me a lot of concern when I purchased the Clarity there really was not enough detail on the power train to answer this simple question (does the ICE have rev matching). Now my primary driving has been all EV and I only use HV mode on trips, and I only take a few highway trips a year, but if I thought I would have to use HV mode a great deal, it would have given me pause about buying the Clarity.

I wish Honda would simply publish a video that shows the power transmission arrangement. Then we would know.

 

Thanks all for the informational replies here.

 

If the engine isn't running, the starter motor/generator is responsible for getting the engine spinning to the appropriate speed. If the engine is running, the i-MMD computer can match the engine speed to the road speed. I would expect a computer-controlled wet-clutch would experience less stressful and less frequent engagements than the human-controlled clutch in a manual transmission automobile. Honda makes more gas-powered engines than any other company in the world, so I have confidence they understand how to make a reliable clutch (says this Honda fan-boy, er, fan-geezer).

 

Did you see the part where I said my Gen 1 insight clutch in the CVT wore out at 80,000 mi? That does not seem all that fantastic to me. Multi-plate clutch and the friction surfaces were down to .03".

I had expected that Honda had the technical prowess to do speed matching, and I had suspected that they do, but I have seen no reference material for it. If you have a citation that you can add so I can see the technical details, I would very much appreciate a link.

Again, I rarely use HV mode so in the end, I decided that it was not worth worrying about, but having also owned a Gen 3 Prius and having admired the absolute beauty of the dual motor e-CVT design, I keep wishing that Honda had eliminated the need for a friction clutch. Gen 3 Prius transmissions are going 350,000 mi in taxi duty with no transmission failures. Now that is what I call reliable.

(And while I say I rarely use HV mode, I took a 2000 mile trip in my Clarity two months ago and with 3000 miles on the car, more miles were put on it in HV mode than in EV mode, and I must have seen that clutch icon come on a couple of hundred times on that trip. That is a lot of clutch engagements. At home though I never use EV mode and have been on the same tank of gas as I ended the 2000 mile trip with).