Consumer Reports Testing

They still lump PHEVs in with all HEVs. Two different animals.

 

Comparing Clarity with Volt which CR did


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Like most here the CR review left me scratching my head. To characterize the engine noise the way they did, was absolutely false and misleading. One would think that upon using up the battery charge, the ICE comes on with a hideous racket every time. Wrong. In fact most people, driving on a highway, would have trouble identifying the point that the engine came to life.

In our 6,500+ miles of driving, I’d say I can count on one hand the number of times the engine made the kind of noise that CR claims was typical with the ICE engaged. Granted, in our case, the few times that it did it was very noisy. But clearly this was the exception rather than the rule.

Then the ‘fussy’ transmission. Never has ours been ‘fussy’. Lift the little R lever and the car goes into reverse. Every time. No exceptions. Amazingly, we get the same 100% response depressing the ‘D’. The car goes forward! Every time. No exceptions. Incredible! How is this ‘fussy’?

As for cornering, it seems to me the car corners very flat with its low center of gravity. It’s a nice handling car. No, it’s not a sports car, but it handles as well or better than other cars in its class.

Me thinks CR has lost its way when it comes to car reviews.

 

Mr. Google says the Honda Clarity PHEV has a MSRP of $33,400. Maybe he meant the advertised MSRP for the Tesla Model 3 of $35,000... but that base trim level won't be available for at least a few more months. The lowest priced TM3 you can actually order at the moment is $49,000 plus delivery charge, and other Tesla models are considerably more expensive.

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I stopped reading CR a while back, when they voted the Renault “Le Car” a Best Buy.... Just before they all disintegrated !


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The Clarity has a CVT, it is the source of the angry bees in the sense the engine can run at any RPM vs the wheel speed. Just because it is an electronic variator instead of a belt driven variator doesn't mean it isn't a CVT.

Source:
Honda themselves refer to it as a CVT.

 

There's nothing variable about it. It's a clutch with binary action - engaged or disengaged.

 

It is electronically variable, imagine an electric belt between the two motors. The motor RPM can be varied vs the wheel RPM. It is multi mode and has a fixed ratio as well when the clutch is engaged.

 

There is a fixed gear ratio between the ICE and the Generator. There is a fixed gear ratio between the driving motor and the wheels. There is a clutch between the generator and the driving motor. When the clutch is engaged, the speed of the ICE and the wheels is fixed. As the ICE gains rpms so does the speed of the car. When the clutch is not engaged, the ICE can provide power for the driving motor and/or charging the battery. The speed of the engine will vary depending on the amount of power needed to drive the car and/or charge the battery.
Some of the early documentation from Honda indicated the car had a CVT. That documentation was later changed to indicate there was no transmission in the Plug in Honda Clarity, and all gear ratios were fixed.

 

aka CVT.

 

With a CVT in any car but the Honda Clarity there is a direct connection between the ICE and the driving wheels. The gear ratio is variable in the transmission that connects between the ICE and the wheels. I think we need another term rather than CVT to describe the workings of the Honda Plug In Clarity because it is different than any other car with a CVT.

 

The clutch connects the engine to the differential and, in turn, the wheels. When this happens, the electronic CVT is no longer in effect--the transmission is no longer variable.

 

Electric variator is the term I have seen thrown around in some tech papers, hence the term eCVT some use. As you say, every company's design is a bit different, and I haven't looked into each in any detail beyond a high level understanding.

It would be nice to see the patents on it, anyone have them? Or maybe SAE paper?

 

This is one I was looking at:
http://docplayer.net/36534016-A-comparison-study-between-power-split-cvts-and-a-push-belt-cvt.html

 

Here is a description of the technology by Honda which was originally used in the Honda Accord Plug In Hybrid and then copied to the Honda Clarity Plug In Hybrid.

The traction motor directly connected to the
driveshaft and the generator directly connected to
the engine are integrated into the equivalent size of
a conventional transmission and the engine-drive
clutch which combines the motor shaft with the
generator shaft is also integrated. Engine power
can be directly transferred to the driveshaft by
engagement of the clutch. Since mechanical
transmission efficiency surpasses electrical
transmission only in the domain of a high-speed
cruise in actual driving cycles, gear ratio of the
engine direct drive is fixed at equivalent of the
top gear of a conventional transmission without
any shifting.

 

All the official Honda sourced material I have read says the Clarity has an e-CVT (whatever that is!) not a CVT.

 

I'd have to tear the clutch down to know exactly what it's doing but I suspect the only variability is in the way it engages and avoids tearing up the drivetrain. The ratio once engaged is fixed. It's not any flavor of transmission, it's a clutch.

 

That paper predates Honda's i-MMD 2-motor hybrid system. It refers instead to my Insight with its single-motor Integrated Motor Assist (IMA) "mild" hybrid system.

I found a new link to the paper where I've learned the most about the i-MMD system:
www.mdpi.com/2032-6653/6/2/325/pdf

 

Can you review a review?