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2011 Chevy Volt
But Volt's true nature may actually be an improvement, plus early reviews are complementary

In the week when auto editors turned in their first reviews of test drives of General Motors' upcoming 2011 Chevy Volt, there's been a bizarre twist that's largely overshadowed these initial impressions.

In a wild twist, Larry Nitz, GM's executive director of electric and hybrid powertrain engineering, has revealed that the gasoline engine actually will drive the Volt mechanically.

Previously, GM had maintained that the Volt was a battery electric vehicle (BEV).  When the battery's 40-mile range (since revised to "25 to 50 miles") was nearing exhaustion, a turbocharged 1.0-liter 3-cylinder gasoline engine kicked in, supply electrical current directly to the batteries and motor to provide more than 200 extra miles in range.

That platform was known as "E-Flex".  But unbeknownst to anyone, GM was pulling a bait and switch.

Today, Mr. Nitz revealed that 
actual powertrain.  The Volt, it turns out, is not a BEV like the 2011 Nissan Leaf.  It is actually a plug-in hybrid electric vehicle (PHEV) like the 2012 Ford Focus or 2012 Toyota Prius EV.

The internal combustion engine (ICE) -- now a 1.4L 84 hp 4-cylinder design -- and the 149 hp permanent-magnet AC electric motor both feed into a planetary gear set and three electronically controlled, hydraulically activated multi-plate clutches.  The resulting automatic transmission is marvel of electro-mechanical engineering offering a blend of efficiency and power.  The entire powertrain is bolted together to minimize noise, vibration, and harshness (NVH) and reduce space usage.

Arguably this advanced transmission is much better for customers than what GM initially 
said it was offering.  As Ford Motor Company pointed out in our recent interview with their head of electrification, BEVs suffer from poor performance in cold or hot weather, as the battery's performance deteriorates sharply. 

So why the bizarre farce on GM's part in claiming its BEV was really a PHEV, when the actual design would be more beneficial to the majority of customers?  Mr. Nitz claims that GM had to deceive the public in order to secure its patents on its unique transmission.  Now with the patents in hand, he was free to go public with the new powertrain platform, dubbed "Voltec", he says.

Turning to what GM had intended to be the focus this week, 
MotorTrend and The Detroit News have taken their first drives in the upcoming PHEV and are quite enthusiastic.

The Detroit News writes:

After I drove more than 32 miles on electric power only — in a very un-eco-friendly manner — the Volt’s little engine began powering the car. This was the moment I had been waiting for: It’s one thing to power a car with batteries, but it’s revolutionary to have a gas engine supply the power to electric motors.
The succession of power is more seamless than a presidential election. The engine is quiet and keeps humming along. There’s never a glitch, a pause or a moment when the engine noticeably kicks on or off. For the most part, once the initial battery charge is drained, the engine produces the electric power to drive the motor. 
...

Most of all, there's nothing to adjust to in the Volt. My 75-mile trip used a total of 0.9 gallons of gasoline. But I would have been happy to drive farther. 

And MotorTrend opines:

The Volt is no sports car, but it blows Toyota's plug-in Prius away (9.8 seconds to 60 mph), and runs neck and neck with a 2.4-liter Malibu in acceleration and handling tests. Figure-eight performance is virtually identical at 28.4 seconds and 0.59 g, and the Volt's 119-foot stops from 60 mph are just 3 feet longer-impressive, given its 226-pound weight disadvantage and low-rolling-resistance tires. (The Prius weighs 376 pounds less than the Volt, yet it just matches its 0.78g lateral grip, trails both Chevys by 0.4 second on the figure eight, and needs 131 feet to stop from 60 mph.)

Based on these reports it appears that GM's "surprise" of the ICE hooking up directly to the transmission to drive the wheels seems indeed to be a good one.  On the other hand, many will likely dwell on the fact that GM pulled a bait-and-switch on the customer.  

After all, some customers really want an honest-to-goodness BEV and may now being a bit bummed that they instead ordered what essentially amounts to a souped up plug-in hybrid.  Others have been vocal critics of the vehicle (and GM in general) and will likely jump on GM's deception as a platform to attack the vehicle (and GM in general).

Perhaps GM was right -- they had to mislead the public to protect their intellectual property.  But the move was certainly a very bad decision in terms of public relations.  GM can only hope that the public settles down and comes to realize the bottom line -- that it's offering them a superior package than what it initially promised to deliver.



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RE: MPG is all that matters
By MozeeToby on 10/11/2010 4:09:45 PM , Rating: 3
Maintenance matters quite a bit too. An all electric drive train is relatively indestructible and having the gas motor only running at the perfect point of its power curve also improves reliability, putting that mechanical power directly to the drive train adds all kinds of complexity and presumably adds full transmission into the mix as well. It takes this from a design that is far simpler than a traditional auto to a design that is far more complex than a traditional auto.

Also, secrecy needed to protect patents? That isn't how the patent system works. If you publish, you're protected. If you don't publish and the competition comes up with the same idea (either via convergent design or a leak) you're SOL. His explanation makes no sense (unless he really thinks that the design is so groundbreaking that it was worth the risk just to get an extra 6 months of coverage at the end of the patent's life).


RE: MPG is all that matters
By Gungel on 10/11/2010 4:20:55 PM , Rating: 2
So why should I route the power from the engine to generator to the battery tho the electric motor to a transmission and than to the wheel when I can just go strait from the engine to the transmission to the wheel without adding all that loss of efficiency. I think it's actually great news for the Volt that we combine range extender and hybrid.


RE: MPG is all that matters
By dubldwn on 10/11/10, Rating: 0
RE: MPG is all that matters
By tastyratz on 10/11/10, Rating: 0
RE: MPG is all that matters
By MozeeToby on 10/11/2010 4:40:58 PM , Rating: 2
A) With a serial hybrid there is little to no need for a mechanical transmission of any kind. Depending on the electric motors used they can power the wheels directly, and a properly tuned engine can directly run the generator.

B) If the gas engine is only being used to charge the battery, it can be highly tuned to a very narrow power band. That gets more power out of a smaller engine, something that is only possible because the engine can always be running at the same RPMs. Being able to tune the engine to a narrow power band allows you to greatly increase the efficiency, enough to overcome losses in the generator and batteries.

C) A drive train that is taking power from two different sources (an electric motor and a gas engine) will be, by definition, more complex than a drive train taking power from only one. That makes maintenance more difficult and failures more likely.


RE: MPG is all that matters
By 91TTZ on 10/11/10, Rating: 0
RE: MPG is all that matters
By foolsgambit11 on 10/11/2010 9:45:57 PM , Rating: 2
Because, amazingly, it is possible to have less total energy transmission losses by going from generator to alternator to batteries to electric motor to simple electric transmission to wheels than having an ICE-to-transmission-to-wheels setup. It's all about how much more efficient a generator running at peak efficiency is compared to a engine tuned for direct propulsion (which needs a wider, but inherently less efficient, power band), coupled with the fact that the losses in each step along the electrical trail are smaller than the losses along the mechanical one.

To be honest, most of my (albeit lay) knowledge of serial hybrid systems like this comes from reading up on sailboat propulsion systems, which do have different torque/horsepower requirements (and user priorities as far as fuel usage and engine running time), so losses in a car's transmission for an electric motor may be greater, and the trade-offs in other ways may make less sense. But serial hybrids have been in use on some high-end sailboats for a few years now, I think.


RE: MPG is all that matters
By bug77 on 10/11/2010 5:41:26 PM , Rating: 3
quote:
Maintenance matters quite a bit too. An all electric drive train is relatively indestructible...


The drive train may be relatively indestructible (the Titanic was supposedly unsinkable), but the battery is not. That's going to have a huge impact on both the maintenance cost and resell value.

There's only one thing sure about EVs: they're not ready yet.


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