Volt - direct drive in Europe?

It become more clear that electric motor torque drop above 50 mph and the ICE sitting there as a dead weight has to do something. Running the generator won't help since the limit is not power but torque.

The thing a lot of people overlooked in the genius PSD design is 72% of the ICE torque goes to the wheel. Combine that with MG2, 50-70mph passing for Prius is outstanding, more pronounce in hilly highways. This will be the weakness of piggyback riding powertrain of the Volt (instead of teamwork).

An attempt to have a direct mechanical output make it more like a Prius but the face patent issue. I can't wait to find out more info.

 

If GM stalls for a few more years the patent will run out.

 

All of those "two-mode" transmissions sitting in warehouses?

Seriously, 'usbseawolf2000' is dead on about the physics and engineering. Toyota and Ford know the pattern that works. But GM and the Germans have a steep learning curve in front of them.

Bob Wilson

 

The more I read about the Volt, the more I am convinced that my initial thought was mostly accurate ... the Volt is GM's feeble response to "green" pressure from Washington.

It will be most interesting to read from afar drivers experiences with GM's offering. As a taxpayer, I hope it is a success .... but I imagine there will be many disappointments .... mostly related to limited range in the Winter, and Summer, and at Interstate speeds. There will be buyers that do not understand the ramifications of EV operation. Many knowledgable writers on PC do understand these limitations, some already have experience with EV's and I suspect they will readily recognize that the Volt is a very expensive, small, niche vehicle whose niche is very limited.

 

This has been debunked

Chevrolet Volt will not have direct engine drive, electric only — Autoblog Green

 

When I "test drove" one, they said 0-60 time would be around 8.5 seconds. I put it in quotes since we were only allowed to go around a little loop. I doubt there is much trouble even at 70, but the thing is really only designed to go up to 90. The could have easily fixed the problem with a more powerfull motor or a 2 speed transmittion. It looks like they designed the thing as a serial/parellel hybrid.

I think the series design is much cleaner when applied to a plug in hybrid. GM seems to have really specked some things to be wrong for series designs. We won't know until it can be objectively tested.

 

It sounds like they've got a long way to go - at least a couple of years, yet I understand they should be releasing this car in the US by the end of the year?

Now that should be interesting.

 

Ok, so there is no direct ICE mechanical output to the wheels but they are using the generator as a second motor (in parallel) to boost the torque.

However, new information was revealed about the hardware of the drivetrain. It has clutches (two or more) and a planetary gearset. That by itself make the Volt more complex than the Prius because Prius has no clutch.

My guess is that both the traction motor and the generator are high speed (13,000 to 15,000 RPM) just like Tesla EV connected to the wheel through reduction gears (~10:1). This result in generator speed not matching the gas engine so a planetary gearset is used to reduce the speed (SRU) of the generator.

Two clutches can be placed like so:

ICE -> C1 -> SRU + Generator(MG1) -> C2 -> Traction Motor (MG2)

If C1 = OFF and C2 = OFF, this is the low speed (<50 MPH) EV mode powered simply by the traction motor.

If C1 = OFF and C2 = ON, both MGs are used for acceleration in EV above 50 MPH.

If C1 = ON and C2 = OFF, this is Charge Sustain mode. ICE generates electricity and the power goes out thru MG2. Additional power goes to charge the battery to maintain SOC.

C1 = ON and C2 = ON would provide direct ICE mechanical output to the wheels. This is a taboo mode because Bob Lutz said so. This would violate and disqualify the Volt as being an electric car. Label matters because that was how the Volt was introduced (RE-EV).

What Andreas Voight probably was trying to say is the possibility of C1 and C2 being turned ON for the Ampera. This can be done by software since the hardware (clutches) are there already.

 

First you should get the misinformation from the first article out of your head. http://www.gm-volt.com/index.php?s=torque

50 mph is no magic number and the car doesn't fall apart there. 50-70 acceleration is a common stat that car magazines often quote, and some confused person decided it was a press release. Since the volt has not been officially launched and Lutz is not in charge I would not put any stock in taboos.

From the article we know that both motors can be turned on but not much else. From previous information the car can get to 90mph with the ice off. We also suspect that the car too close to launch to make anything but minor changes to the us version.

 

The Thread quite clearly states "Direct Drive In Europe?". It does not say the US version will have this and with only months until launch it is probably too late anyhow.

The comments are that GM apparantly said it never would have direct drive though personally does it really matter one way or the other? Perhaps the Volt and the Ampera could have different drive systems to suit different markets, but then this will end up getting more complex and expensive. Toyota keep costs down by having the Prius pretty much the same worldwide.

The Volt/Ampera is a stylish car and has many merits. Will it flop or be a winner? Did GM go into the EV project half a**ed because they were forced to? Who knows. If it does flop there's still Toyota and Nissan (and Renault too here in Europe) to carry on with EV's.

 

Thanks but I was aware of that report before my post. It confirmed the existence of clutches and planetary gearset, which was the basis for my thought of it's operation and possibility of mechanical direct drive enabled through software. It is nothing more than a conjecture from my part (how I would have done).

"The author, Andrew English, claimed the 65% calibration version Ampera/Volt prototype seemed to have a flat torque curve at high velocity. He wrote that an engineer claimed GM was planning to correct this by connecting the gas engine driectly to the drivetrain. I had checked in with Rob Peterson who said the claim was untrue and unfounded, and is not the case. Rob explained to us the Volt uses clutches and a planetary gear system to maximize performance and efficiency."

 

Hummm, so let's look at this history of this vendor, GM:

• took perfectly good EV1s and crushed them instead of offering forsale at any price
• walked away from the Precept in 2001
• claimed 'hydrogen fuel cells' as replacement
• called auto-stop a "mild" hybrid
• touted "two-mode" transmissions but offered only in +$50k boats
• killed Saturn VUE with "two-mode" (then sold Saturn)
• went bankrupt
• announced Volt in 2007 and it won't be out until late 2010
• Volt development has been well publicized (aka., greenwash)

It reminds me of:


I'm not holding my breath on this one. GM could do the right thing but they've spent the last decade doing the wrong things time and time again. So I'll believe it when I see it on the show room floor of the local GM dealer. Until then, just more noise.

Bob Wilson

 

I feel a little sympathy for the good men and women in GM's design and engineering departments that have skills and abilities, but which appear to be "squashed" by managements yielding to congress ... and unions. I agree w/ bwlson4web, GM's management style certainly does not provide any basis for confidence in their program.

Many question GM's cancellation of the EV1 program, and with good reason. I have never understood why, and point to the cancellation of Saturn Division, in almost the same questionable way ... after all the hype about new inovations, technology, and marketing ..... then to drop it .... and retain Hummer????? (I know it too is gone now)

 

The possibility of direct drive has been speculated at since at least November when this gm clarified the generator could be used as a motor. This link was included in the above article.

Engineering Design of the Chevy Volt’s Two Electric Motors

I thought you were influenced by the first bogus article by giving operation of both motors in drive at 50. GM clearly does not want to tell us exactly what is going on, or when both motors are used and are keeping that information proprietary.

Reasons why they may not want to use the generator, clutches, and gearset to directly couple the ice are pure speculation. If the ice was needed for highway torque, then all of the ev range estimates are bogus.. The original bogus article said the engine is needed during ev driving, which definitely sounds like a bad idea. If on the other hand the motor was specified correctly directly coupling the ice might cause vibration, noise, and wear to the system that GM does not want. Doing this might increase efficiency in CS mode, but at least since last November GM has consistently saying they are not driving the wheels from the ice.

Only time and test drives will be able to tell if the motor has adequate torque at high speeds. This is a separate issue.

 

Problem is ... often, GM "truths" end up being lies. Thus, if GM says it's a lie - it may be a truth.
:thumb:

.

 

Although you may have a point i like to try a defend GM a little.

1. About the EV1 Toyota has never released one....
2. And the whole bankrupt thing, at least they paid their worker 20-75% more than i ever heard of Toyota paying. So at least up to now they were fair to their workers.
3. All companies are evil, when you really think about it...

 

Hmmm even little old me finds the above quite interesting

1, What about the Rav4 EV?
2, GM paid their workers upto 75% more than Toyota? No wonder GM went pop. lol. At least they're fair to their workers? Sounds like either Toyota are paying below minimum wage or GM were throwing money away.
3, Mine isn't.

 

see above in bold.

 

LOL you two guys got me I didn't know about the rav ev. I retract my statement.
Sorry for not doing my research. Did Toyota sell them? Or did they do like gm and take them back and stop selling them?

The second one about gm being hostage to their unions that was a good thing. For like 30 -50 years( i'm not postive how long the union was around) they had to pay thier workers a fair wage and still the ceo's of the company got their millions. I know they did fall apart in the last few years, but at least when they did make alot of money they paid everyone good money. But now in order to compete they make cars in Mexico so i will say there only fair to the us workers now and that has changed alot over the last few years.

yes they were very fair to the white collor as well, i knew many that made 100k to 200k a year. I still know some that make 150k a year. They were more fair the white than the blues.

I guess what i'm trying to say is that over the 30 years my dad work for gm they never needed a bailout, and during that whole time they gave the workers a pension and a very good wage. Now things are different and they need to learn to compete with other companies with way lower wages and no pensions.

Take walmart why can't they share the billions and billions of profit with the millions of people that make 7-9$ an hour that are a big part of the reason walmart does so well? I guess the walmart brats need more millions, and so do the share holders.