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NY Times- GM/Chrysler dual-mode full hybrid

Old 06-28-2005, 03:53 AM
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Default NY Times- GM/Chrysler dual-mode full hybrid

While I certainly agree that a smaller improvement over a large class of more popular vehicles (trucks, SUVs, family-size vehicles) nets a greater gain than large improvements in the not-as-numerous compact class most of us here drive, the fact that this is a GM initiative makes me suspicious of both the timeline and chances of fully achieving the stated goal. Still, my best wishes for success! Someday soon, 'hybrid' will be just another powertrain option for almost all vehicles- THEN we will see more mass acceptance.

New Hybrid May Curb Trucks' Thirst

FOR all the hoopla over hybrids, sales of the high-efficiency gas-electric vehicles in the United States are still just a small slice - about 1 percent - of the new-car market.

Until recently, hybrid vehicles, too, were small. But a growing stream of sport utilities and midsize sedans with hybrid powertrains is changing that profile.

For instance, Toyota's line of hybrid models has expanded from the first-generation Prius, a pipsqueak that arrived in the United States in 2001 with a 70-horsepower gasoline engine and a 44-horsepower electric motor, to include larger vehicles like the Highlander, a hybrid utility wagon with a total of 268 horsepower from its gas and electric power plants. Hybrid luxury sedans that promise V-8 performance from 6-cylinder engines, like the Lexus GS 450h that goes on sale next spring, are in the works.

The perception of hybrid vehicles broadened again with the announcement last December that DaimlerChysler had joined General Motors in developing a "two mode" hybrid system. To be used initially in full-size S.U.V.'s and pickups, the new system also represented a fundamental shift in the mechanical arrangement of hybrids: in contrast to the layouts used by Honda and Toyota, the two-mode hybrid places its electric motors inside the transmission housing, an arrangement made possible by the compact size of the motors.

The design, according to G.M., is part of a strategy to develop hybrids that improve fuel economy at highway speeds as well as in the city, using two separate modes of operation. The electric motors deliver their power through variable-ratio gear sets, which allows them to be smaller and lighter while drawing less electricity. Smaller batteries and power controls than those required by single-mode systems can also be used.

G.M. says that the ability to package the electric motors directly within the transmission housing also offers a competitive advantage, making it easier to adapt hybrid technology to the wide range of vehicle sizes, engine types and drive systems in its global model portfolio.

Rather than develop hybrid systems first for small vehicles and then scale it up for trucks - as other carmakers have done - G.M. borrowed the two-mode design from a system pioneered by its Allison division that is currently used in 350 city buses. G.M.'s position is that incremental economy gains on popular large vehicles - full-size pickups are best-sellers in the United States - will have a greater effect than big improvements on smaller, less popular cars.

The two-mode hybrid system will make its debut in the Chevrolet Tahoe and GMC Yukon in late 2007, and is expected in pickups the following year. (It is unrelated to the system currently used in Chevrolet and GMC pickups, which G.M., in something of a stretch, also labels a hybrid.) A hybrid Dodge Durango is expected soon after G.M. introduces its S.U.V.'s; Mercedes-Benz cars will use the two-mode design, too.

In designing a hybrid system for pickups and large S.U.V.'s , G.M. engineers took to heart the strong preference expressed by customers for V-8 engines. To minimize the V-8's fuel consumption, the two-mode system makes use of existing technologies like cylinder deactivation - a system G.M. calls "displacement on demand" - to shut down half the engine when full power is not needed. Like other hybrids, the engine shuts off when the vehicle comes to a stop, then instantly restarts when the accelerator is pressed.

The main distinction of the two-mode hybrid, though, is the use of a second set of gears configured specifically for moving big vehicles at highway speeds. The Honda and Toyota systems (and the Ford Escape Hybrid, which shares Toyota technology) use a single set of gears for both city and highway driving.

Larry Nitz, executive director for hybrid power train engineering at G.M., explained: "It's two electronically controlled, continuously variable modes, and they have a point, a gear ratio, at which all the speeds synchronize. At that gear ratio, the engine switches from one mode to the other mode without a speed change." As a result, Mr. Nitz said, the transition between modes, at a speed that is equivalent to second gear in a conventional car, is nearly imperceptible.

"When you're in the economy or city mode, you lean on the electric motors more, because the electric side allows you to operate more efficiently at light loads," Tim Grewe, chief engineer for rear-drive hybrids at G.M., said. "When you are in performance or highway mode, you use more gears, because gears operate more efficiently for the high loads."

Each of the two-mode hybrid's two electric motors is about half the size of a motor used in today's hybrids. Even so, the two-mode system is powerful enough to move a full-size pickup through stop-and-go traffic without assistance from the gasoline engine, a trait that qualifies it as a full hybrid.

At high speeds, the second of the two gearing sets is engaged, essentially to reduce the demands placed on the electric components and to allow the V-8 engine to do what it does best: accelerate briskly and cope with high loads and towing.

The two-mode system is expected to achieve the same levels of fuel economy in both city and highway driving; typically, full hybrids get better fuel economy in the city than they do on the highway.

G.M. has not revealed exactly how it will pack so much functionality into such tight quarters, how much the system will cost or how many it expects to sell.

Competitors remain skeptical about the benefits of a hybrid with two modes and two sets of gears. "Until you see the mechanization, you don't know what those words mean," David W. Hermance, executive engineer for environmental engineering at Toyota, said, referring to the two-mode name.

Dave Reuter, a hybrid engineering consultant who worked on the Ford Escape Hybrid, sees the two-mode system as a logical evolution of the technology. "Hybrids started with a single motor concept, then a motor-generator was added, allowing multiple configurations for splitting the power between gas and electricity." Mr. Reuter considers this development another venture in the "discovery and development curve."

While small hybrid cars may carry fuel economy ratings that promise a savings of 40 percent compared with conventional vehicles of similar size (though it can be hard to make direct comparisons), G.M.'s projected improvement for the two-mode system is just 25 percent. But a 10 percent increase in fuel economy across the entire large-pickup truck market would save more than twice as many gallons of gasoline as an equal percentage gain in small cars, according to Walter McManus, director of the Office for the Study of Automotive Transportation at the University of Michigan.

The reason is simple: Americans buy millions of pickups every year. And while the mileage figures may be less remarkable than those of small cars, the savings are significant and the potentially high production volumes open opportunities to cut the cost of future hybrids.
Old 06-28-2005, 06:42 AM
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Default Re: NY Times- GM/Chrysler dual-mode full hybrid

As a 'Pipsqueak' II driver, I agree with your assessment:
while small improvements in mileage of high sales volume vehicle will do more for the overall reduction in oil consumption than large increases in low volume cars, I object to the whole idea of trying to make large, oversized, heavy vehicles socially acceptable. I think we should spend at least as much effort on convincing people that such vehicles are not always needed or justified. Improving efficiency of such large vehicle will make people feel better (or less bad) about buying them, and we will still end up with a very high fleet consumption, much higher than if the majority of vehicles sold were of a reasonable size (and efficient on top of that). Decades ago, most folks were happy with reasonably sized vehicles. Then marketing shoved SUVs and trucks down our collective throats, and who truly needs 4WD? 95% of vehicles that have such a feature never use it. I think the rush of some companies to develop 'large' hybrids, is very dangerous. They obviously do this to preempt those companies that have been thinking ahead, from gaining too much of a technological lead (it remains to be seen how fast they can really accomplish this catching up). Yet these vehicles will be large, they will be hybrids, yes, but I doubt they will be anywhere near as technologically advanced as the Pipsqueak. This will result in large SUVs being 'ok' once again, and with only a marginal increase in efficiency (but we now have a 'hybrid' in the garage, wohooo). I really wonder if this is not mostly driven by the companies that are pushing this making most of their $$$ with large SUVs and trucks, and that's how they would like to keep things. We've all heard about the disappointing performance / efficiency of the Allison buses.
I know some may beg to differ, and this is my very personal decision, but a Suburban or Expedition is just wrong 98% of the time (there are times when they are appropriate, if used to capacity as people or gear carriers!), and making them hybrid does not make them any less wrong. One again GM & Co are barking up the wrong tree, and I just hope that little pipsqueak will continue to run up to them and raise the leg....
Old 06-28-2005, 10:02 AM
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Default Re: NY Times- GM/Chrysler dual-mode full hybrid


___It is one thing to drive a Prius II because you want too. It is an entirely another matter to tell the rest of the country that a large, and heavy vehicle isnít socially acceptable. You happen to be in the minority on this one. What has to become more socially acceptable is much smaller automobiles for the masses. Even with todayís dire warnings of impending Peak Oil and Global Warming, I still like the creature comforts and safety of a true mid-sized or larger automobile compared to a small one.

___Another tact. A vehicle that weighs twice as much will always use more then twice as much energy to accelerate up to a given speed. All other efficiency terms being equivalent of course. The counterpoint to this is once up to speed, that larger vehicle does not necessarily consume twice the energy to maintain a given speed as the smaller one. A good case study for this is the Corolla vs. the MDX. With all the techniques I use today, the 4WD - 4,500 # MDX is good for between 33 and 37 mpg out on the highway. The much smaller, far lower performance, much less luxuriously equipped Corolla is good for ~ 50 mpg. I give up ~ 15 mpg to drive a fully loaded and semi-lux 4WD SUV. Was it worth it? Did you not give up ~ 20 mpg to drive the Prius II instead of an Insight 5-speed? How small is small? Should we not all be driving relatively smallish 1.6 L CDTi equipped Ford Focus C-Maxís or Prius IIís at a real world 50 and 48 mpg respectively? Let us all be mandated to an even smaller Honda Fit w/ a yet to be developed 1.5 L iCDTi for maybe 80 lmpg? One manís large and oversized vehicle is another mans basic want or need. In your case, you are sitting in the middle at ~ 2,890 + #ís although near the high end of the FE scale if course.

___Finally, as far as $ís are concerned, if Toyota did not sell all the 4WD SUV and P/U trucks that they do, do you think they would still be making handsome profits thus allowing the healthy R&D budget to design and manufacture the Prius I, II, HH, and RXh? Making the same handsome profits and reinvesting those same profits back into R&D for future hybrid designs on the much smaller and probably far less profitable Camry, Corolla, and Echo would be a real stretch imho.

___Good Luck

___Wayne R. Gerdes
___[email protected]

Last edited by xcel; 06-28-2005 at 10:07 AM.
Old 06-28-2005, 11:54 AM
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Default Re: NY Times- GM/Chrysler dual-mode full hybrid

I'm painfully aware that I'm a minority in terms of the social acceptance of small size, vehicles that is. Personally, I do think small vehicles can have all the creature comforts and safety of large ones. My previous car was a 2003 MINI Cooper S, and stiff sports suspension aside (on purpose), it was the best vehicel by far I have ever driven, in terms of seat comfort, ergonomics, creature comfort, and for many reasons I felt much safer in it than in much larger vehicles (not just active safety, but the way it was built, 6 airbags, etc..). In terms of driver comfort and space, I'm sorry to say it far outranked my beloved Pipsqueak II. I do agree with you that by and large it would be nice to allow people to chose what they prefer. However, there are obvious limits to that idea, as we would for example not allow people to drive tanks on public roads (ok, we do, but they are called SUVs for political correctness, but you get what I mean). And yes, mass matters in terms of energy required to accelerate, largely not relevant at highway cruising, but size does matter for highway cruising, since larger vehicles create more drag, and require larger tires, which create more drag, etc.... Generally, size and mass are corellated afterall.
The last point is interesting, and I'm glad you bring it up. I don't know enough about the development cost of the Pipsqueak and HSD, and when most of those efforts were started vs when Toyota started making major profits from trucks and SUVs. I agree, in some ways it is disappointing that Toyota is pushing trucks and SUVs as much as hybrids. I would feel better about my Pipsqueak II if it hadn't been developed using profits from guzzlers. Still, it's better than nothing!
Good post though Wayne, thank you!
Old 07-01-2005, 02:38 AM
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Default Re: NY Times- GM/Chrysler dual-mode full hybrid

I would stand up and applaud if GM was to discontinue their non-hybrid vehicles, but that is obviously not the case. They will continue to manufacture and sell tons of conventional vehicles, while bathing in the publicity that the hybrid hype brings. It's good that they are introducing more FE products, but just as an option? I don't think that's really good enough, knowing how they push the profit-monkey SUVs and trucks. If catalytic converters were just an option, would they be significantly popular enough today to prevent any pollution? I really doubt it, in fact I think very few people would choose that option. FE is a bit different that pollution control, I know... but it is part of the same picture, less burnt gas, less pollution. Perhaps by 2010 there will be more concern for FE, and the "bugs" will have been worked out of the systems that we can get these corporations to stop selling stone age technology. I know that sounds drastic, but so did mandatory pollution control laws, and just look how people are "getting by" with catalytic converters etc.
Old 12-23-2006, 01:00 PM
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Default Re: NY Times- GM/Chrysler dual-mode full hybrid

Full hybrids hold a lot of promise when coupled with the idea of a plug in hybrid. Pickup and SUV drivers are not immune to gas prices or the idea of saving $$. I think that if you offered someone the idea of driving to work and back for less than a buck a day, there would be a lot of drivers that would take that option. But not if they have to drive a small vehicle. With 2 million + new pickups built every year the potential fuel savings are incredible!

That's what I am hoping happens with GM's big hybrid trucks. GM recently promised to build a plug in hybrid VUE. They just need a battery that's reasonably priced. If you drive a Prius, Camry, or Ford Escape, and have a little extra coin (well, OK, $12K is a lot of extra coin) there's a company called Hymotion (hymotion.com) in Canada that makes a battery that will make your vehicle a plug in hybrid. Today!

I think it is inevitable that we will switch to hybrids then probably electric, but for a lot of us, its not happening fast enough.
Old 12-23-2006, 05:04 PM
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Default Re: NY Times- GM/Chrysler dual-mode full hybrid

Hi folks,

I look forward to seeing more technical details about the GM dual-mode hybrid. There are some aspects that bother me from what little is known. For example, there appears to be a hydro-mechanical torque converter and those are often pretty lossy. Also, it looks like there are coolant tubing, another signature of energy loss. BUT we really need to see the product and test it.

I do have an engineering rule of thumb:
EV power / (ICE power + EV power) = quality of hybrid

So for my NHW11:
33 kW / ( 52 kW + 33 kW) = 38.8%

For the current NHW20:
50 kW / (57 kW + 50 kW) = 46.7%

For a recent GM hybrid:
4 kW / (126 kW + 4 kW) = 3.0%

I'm looking forward to seeing a significant improvement in the GM hybrid offerings.

Bob Wilson
Old 12-23-2006, 06:42 PM
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Default Re: NY Times- GM/Chrysler dual-mode full hybrid

Thanks for the "rule of thumb" Bob. No disagreement from me about GM needing to make improvements to their hybrid offerings. That said, I would like to see Toyota come up with cylinder deactivation for their V6s and V8s. They could really use that to improve the freeway mileage on their larger models.

I thought I had read where this two-mode hybrid transmission was a joint project involving BMW and Daimler-Chrysler. This made me hopeful that there would be a large volume of brands and models with a hybrid option. None of these companies will do themselves any good if their new offerings perform like the current GM hybrid offering.

I'm really hopeful, both for GM, and everyone else, that they have big success with this product. I think the real promise of hybrid technology will come when we can get hybrids technology into a large % of SUVs and light trucks. Especially a plug in.

I would love it if we were to have the problem of having so many plugins that we have to come up with more power plants. Wishful thinking maybe, but that's what I'm hoping for.

Thanks again for the "rule of thumb."
Old 12-23-2006, 09:34 PM
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Default A 16 mpg city-CC would be nice.

If I have the money,I would love to give GM CC a try. Most of the full sized V-8 trucks get about 11-13 mpg in pure city driving(the hemi gets much worse). It the GM crewcab got an honest 16 mpg city, it would be a heck of a truck. A buddy of mine get 23 mpg highway with his 2006 5.3 CC Chevy.
If Chevy cleans them up a bit more, then 25 mpg highway is possible with pure ice.Move to a small diesel-maybe a 3.5 liter straight six,and you might approach 30 mpg highway at 60-65 mph with a full sized pickup.It would be a good long trip vehicle,and a good evacuation,Home Depot/ house repairs type vehicle.
A true 4 door pickup is pretty versatile vehicle.
XCEL-Yep, the MDX is a really nice trip vehicle. We spent 16 hours going 250 miles in our Pilot last August; it was not too bad.
You can put an air mattress in the back,fold all the seats,fill in the space between the ft seats and the headrests of the backseats with plywood and foam, and you have about 78" of sleeping length-with enough width for two adults and two leggy greyhounds.
Old 12-27-2006, 08:10 PM
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Default Re: NY Times- GM/Chrysler dual-mode full hybrid

Originally Posted by xcel View Post
It is one thing to drive a Prius II because you want too. It is an entirely another matter to tell the rest of the country that a large, and heavy vehicle isnít socially acceptable. You happen to be in the minority on this one. What has to become more socially acceptable is much smaller automobiles for the masses. Even with todayís dire warnings of impending Peak Oil and Global Warming, I still like the creature comforts and safety of a true mid-sized or larger automobile compared to a small one.
A few hundred years ago, British scientists were warning that if actions were not taken, the white race would cease to exist as a result of the colored people. A few decades, scientists were warning that in the future we would experience global freezing. Now some scientists are saying that we are causing the planet's temperatures to rise, while others say otherwise and are being censored. Posterity will not remember those individuals that identified the charlatans for what they really are, much like hundreds of years ago or more recently, a few decades ago.

I find large vehicles, such as those pickup trucks that rival the Hummer, to be disgusting, not because of any potential to cause global warming that they are conjectured to have, but because those vehicles increase the demand for oil, raising gasoline prices and obstruct my view of the road, hurting my fuel economy by cutting my ability to coast to red lights. I really like it when I see a Toyota Prius because they contribute less to the demand for oil than other vehicles, lowering prices while allowing me to see the lights ahead. Being realistic, those are the two main reasons to encourage people to have smaller, more efficient vehicles, and if people would stop trying to get the government to fix things, we would see people buying them.

By the way, I cannot think of a more severe insult that could be attributed to Americans than "the masses;" every single American has an identity and is not part of some swaying mass, which is why we Americans do not use such a word to describe ourselves. I would appreciate it if you would show more consideration when selecting your choice of words.

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