More Volt Hybrid / EV drama for some Friday fun! Okay, there's not a lot of drama here, but if you, like me, miss college lectures, you should get a kick out of this GM Voltec powerflow demonstration. It's a neat piece of animation that shows the working of an incredibly tricky bit of tech. (Seriously, any of you kids seen a blown-out schematic of a planetary gearset? Whoa....)
You'll note that the combined ( gasoline engine--gasp-- + electric Motor ) returns 10-15% better fuel economy on the highway. That's not a smalll percentage for a vehicle that should see mid-30s.
Oh, fine, there we'll add some drama here, but it's after the jump and after the video.
GM Vice Chairman Tom Stephens to The Detroit Bureau 10-13-2010, "You can run that (gasoline) engine all day and the car won't move an inch because there is no clutch," he said. "I know because I'm the guy who decided there should be no clutch."
The guy presenting this video and pointing to stuff: "We're going to see the three clutches; the so called C1 that grounds the ring gear, C2 that connects the generator to the ring gear, and C3 that connects the engine to the generator."
3....0......We're just sayin....
120mmgun says:
02:15 PM, 10/15/10
What are you "just sayin"?
bankerdanny says:
02:34 PM, 10/15/10
I'm kind of leaning towards the IL is overreacting here school of thought.
I suspect that what he meant was there was not a driver controlled clutch, ie a 3rd pedal or a DSG. The clutches that control the connection between the engine and the generator and the transmission are controlled completely by the car and the driver has no ability to control the actuation other than to accelerate to and then hold speeds over 70 mph.
I agree that GM sold the Volt as something that it is not, a car directly powered by electricity 100% of the time. The car they are delivering is 100% electric motor driven most, but not all the time.
In the end, the distinction is not meaningful to me. A very limited electric only range means that for MOST drivers the gas engine was always going to to be needed at some point for the car to be able to continue to move, so for me this car has always been a type of hybrid rather than an EV which for me means a car with no internal combustion engine of any kind.
If the Motor Trend test is accurate, a mixed use average MPG of 124 is pretty damn amazing, and something that GM should rightly be proud of.
half_ton says:
03:38 PM, 10/15/10
It's a general inconsistency that IL is pointing out. You would think that after all the hype and controversy surrounding the Volt and GM over the past week that if nothing else EVERY GM employee who speaks on the Volt publicly would same the same thing and not contradict each other.
Apparently these guys STILL haven't figured it out . . .
lostboyz says:
05:05 PM, 10/15/10
I can't wait to see 1487's response, maybe the video is a lie planted by IL or something. Or to say a clutch doesn't constitute a direct linkage and its not actually providing any energy.
rotaryrocket says:
07:27 PM, 10/15/10
That looks like the back of Mike's head from MST 3000...
nimisys says:
10:25 PM, 10/15/10
Planetary gearsets are not that difficult or even new. They have been in every automatic transmission for the last 60 years and longer, and they have been coupled together in just about every way possible. Hybrid transmission planetary sets are about as simple as they come, generally a single simpsons gearset with one or two clutch packs and an electric motor.
As for this GM unit, looking at the 3 clutches used, i don't see one that is used with the primary intended purpose of running the vehicle off the engine. C1 links the electric motor to the wheels, C2 links the generator to the wheels, C3 links the generator to the engine. Which one is there to link the engine to the wheels? I think during testing they discovered by bringing on all 3 clutches at the same time they could gain more effiency, similar to bring on the converter lockup on an automatic transmission. End the end, isn't increasing efficency the goal? Having the engine being capable of driving the wheels is a simple by-product of the packaging, the engine is linked to the wheels through the generator. the simple fact is that the engine is not needed to run the vehicle outside of a generator function, however there are times that using it is more efficent than lugging it around and ignoring it. Additionally since the engine is clutched to the generator it must spin at the same rpm. This means the window for the engine to be used as an efficent booster is going to be narrow, increase the generator speed too much and you push the engine too fast, drop it too low and you stall the engine.
kyolml says:
11:39 PM, 10/15/10
Well, if this illustration are accurate, the engine really not really directly driving the wheel. It's a byproduct of driving the generator and instead of driving the generator to the battery, it drive the generator to the wheel. From strictly definition, GM could be better off saying that they are not lying it's 100% electric car because the "generator is driving the wheel". Smart!
opfreakx says:
02:37 PM, 10/17/10
kyolml
using that kind of GM logic the engine rarely directly turns the wheels. After all it almost always goes to a fly wheel. Which then can act on a clutch plate, which then connects to some gears, through some shafts, and finally the wheels.
If its an automatic, then its spinning a fluid, which then turns gears which then turn wheels. so again its not 'directly' turning the wheels.
GM gave the most typical PR spin to try to blind the public.
IMHO, I dont really care that the engine powers the wheels. I care about being lied to, and being told that this was an 'all electric' car. Which it isnt'.
Does any of this really matter to how the car peforms? not really.
on the other hand this car is INefficent when the gas engine is operating. MT had what 33-36mpg freeway? that sucks
allthingshonda says:
07:36 PM, 10/20/10
GM has always said that the Volt was going to be equipped with a gasoline engine. They initially said the engine would be used to power the generator to provide electricity to move the car. The only thing that I can see that changed is that the engine will be coming online earlier and more often than they originally stated. The engine's job is still to provide power to the generator. Looks like someone dug up old files from the days when GM owned the Electromotive Division.
The Volt is really very similar to how Locomotives are designed. They have huge powerful diesel engines, but the engines are only used to create electricity to power traction motors they are not directly connected to the wheels. Like locomotives the Volt's engine doesn't seem to have to rev very high to maintain speed or accelerate. It doesn't seem to have to rev more than a few thousand rpms to provide max juice.
They are staying firm that the Volt is capable of 100 mph on batteries alone on a full charge. I don't think it is a full EV but it is not really a Hybrid like a Prius. GM seems to have developed something in the middle. We could actually be looking at the future of automotive propulsion. The engines in vehicles will only be used as onboard electric power plants like the Volt. Performace will not be defined by the size of the engine but by how many KW the generator can put out and how much the traction motors can handle.