Quote:
Just the Facts:
* Despite promises that the Chevy Volt will operate as an electric car at all times, it will in fact at times be directly driven in part by its internal combustion engine.
* The mechanical link between Ecotec internal combustion engine and drive wheels will be at high speed.
DETROIT — It's the big headline currently on GM's media news site:
"2011 Chevrolet Volt Reinvents Automotive Transportation IN A Complete No Compromises Electric Package"
Um, well, no. Even conceding that all engineering projects involve compromise and chalking that phrase up to marketing hyperbole, the Chevy Volt isn't as electric as GM pretends it is. And it isn't as electric as GM has been saying for the past three years. You know, GM statements like this one:
"The Chevrolet Volt is not a hybrid. It is a one-of-a-kind, all-electrically driven vehicle designed and engineered to operate in all climates."
In fact the Chevy Volt is a hybrid and it has more in common with conventional "parallel" hybrids like the Toyota Prius than the marketing hype led us to believe. There are circumstances in which the Volt operates with the internal combustion engine directly driving the front wheels. That's right, like a Prius.
At the heart of the Volt is the "Voltec" propulsion system and the heart of Voltec is the "4ET50" electric drive unit that contains a pair of electric motors and a "multi-mode transaxle with continuously variable capacity." This is how GM describes it:
"Unlike a conventional powertrain, there are no step gears within the unit, and no direct mechanical linkage from the engine, through the drive unit to the wheels."
The 4ET50 is, however, in fact directly bolted to the 1.4-liter, four-cylinder Ecotec internal combustion engine. When the Volt's lithium-ion battery pack runs down, clutches in the 4ET50 engage and the Ecotec engine is lashed to the generator to produce the electric power necessary to drive the car. However under certain circumstances — speeds near or above 70 mph — in fact the engine will directly drive the front wheels in conjunction with the electric motors.
As in the Prius, the Volt's drivetrain includes a planetary gear set that acts as a transmission. The intricacies of planetary gears are many, but in rough terms each element (electric engines and internal combustion engine) of the Prius or Volt drivetrains are hooked up to different elements of the gear set. In the Volt, its Ecotec engine is clutched to the outer ring gear and as the car's speed reaches the edge of efficiency for the electric motor, that ring is set from its normally rigid mounting in the 4ET50's case and allowed to spin. That has the Ecotec driving the front wheels.
The Volt's Vehicle Line Engineer Doug Park confirmed that there is, on occasion, a direct mechanical connection between the internal combustion engine and drive wheels in an interview with Norman Mayersohn of The New York Times. This isn't idle speculation or educated inference, it's an admitted fact.
What's vexing here is that GM hasn't been forthright in explaining this. It's not like this sort of operation isn't an integral part of the Volt's drivetrain — the engineering team has to have known this is how the car would work for a while now. But even today, GM's press releases and consumer information insist that the Volt is always and solely electrically driven. That's simply not true.
Frankly, we were lied to. Back in June, John O'Dell who edits Edmunds.com's eco-obsessed sister site The Green Car Advisor reported on rumors that last minute revisions would have the Volt using a direct mechanical connection between its Ecotec engine and drive wheels. So O'Dell asked GM's spokesman Robert Petersen directly if the rumors were true. Petersen clearly denied the rumors and insisted the Volt (and its European brother the Opel Ampera) would be driven solely by electricity.
Inside Line says: Don't believe everything GM says. No matter how many times they say it.— John Pearley Huffman, Correspondent
http://www.insideline.com/chevrolet/volt/2011/gm-lied-chevy-volt-is-not-a-true-ev.html
Just the Facts:
* Despite promises that the Chevy Volt will operate as an electric car at all times, it will in fact at times be directly driven in part by its internal combustion engine.
* The mechanical link between Ecotec internal combustion engine and drive wheels will be at high speed.
DETROIT — It's the big headline currently on GM's media news site:
"2011 Chevrolet Volt Reinvents Automotive Transportation IN A Complete No Compromises Electric Package"
Um, well, no. Even conceding that all engineering projects involve compromise and chalking that phrase up to marketing hyperbole, the Chevy Volt isn't as electric as GM pretends it is. And it isn't as electric as GM has been saying for the past three years. You know, GM statements like this one:
"The Chevrolet Volt is not a hybrid. It is a one-of-a-kind, all-electrically driven vehicle designed and engineered to operate in all climates."
In fact the Chevy Volt is a hybrid and it has more in common with conventional "parallel" hybrids like the Toyota Prius than the marketing hype led us to believe. There are circumstances in which the Volt operates with the internal combustion engine directly driving the front wheels. That's right, like a Prius.
At the heart of the Volt is the "Voltec" propulsion system and the heart of Voltec is the "4ET50" electric drive unit that contains a pair of electric motors and a "multi-mode transaxle with continuously variable capacity." This is how GM describes it:
"Unlike a conventional powertrain, there are no step gears within the unit, and no direct mechanical linkage from the engine, through the drive unit to the wheels."
The 4ET50 is, however, in fact directly bolted to the 1.4-liter, four-cylinder Ecotec internal combustion engine. When the Volt's lithium-ion battery pack runs down, clutches in the 4ET50 engage and the Ecotec engine is lashed to the generator to produce the electric power necessary to drive the car. However under certain circumstances — speeds near or above 70 mph — in fact the engine will directly drive the front wheels in conjunction with the electric motors.
As in the Prius, the Volt's drivetrain includes a planetary gear set that acts as a transmission. The intricacies of planetary gears are many, but in rough terms each element (electric engines and internal combustion engine) of the Prius or Volt drivetrains are hooked up to different elements of the gear set. In the Volt, its Ecotec engine is clutched to the outer ring gear and as the car's speed reaches the edge of efficiency for the electric motor, that ring is set from its normally rigid mounting in the 4ET50's case and allowed to spin. That has the Ecotec driving the front wheels.
The Volt's Vehicle Line Engineer Doug Park confirmed that there is, on occasion, a direct mechanical connection between the internal combustion engine and drive wheels in an interview with Norman Mayersohn of The New York Times. This isn't idle speculation or educated inference, it's an admitted fact.
What's vexing here is that GM hasn't been forthright in explaining this. It's not like this sort of operation isn't an integral part of the Volt's drivetrain — the engineering team has to have known this is how the car would work for a while now. But even today, GM's press releases and consumer information insist that the Volt is always and solely electrically driven. That's simply not true.
Frankly, we were lied to. Back in June, John O'Dell who edits Edmunds.com's eco-obsessed sister site The Green Car Advisor reported on rumors that last minute revisions would have the Volt using a direct mechanical connection between its Ecotec engine and drive wheels. So O'Dell asked GM's spokesman Robert Petersen directly if the rumors were true. Petersen clearly denied the rumors and insisted the Volt (and its European brother the Opel Ampera) would be driven solely by electricity.
Inside Line says: Don't believe everything GM says. No matter how many times they say it.— John Pearley Huffman, Correspondent
http://www.insideline.com/chevrolet/volt/2011/gm-lied-chevy-volt-is-not-a-true-ev.html
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