Design Article
TECH TRENDS: When is a hybrid not a hybrid?
Rick DeMeis
10/6/2011 9:06 PM EDT
Buick's 2012 LaCrosse comes standard with a hybrid electric power train, but the company just calls it "electric assist" for its luxury car buyers (a decision apparently made by the marketing types).
Earlier this week, this editor and fellow members of the New England Motor Press Association were given a detailed preview of the new LaCrosse—which significantly is the first car model (other than a dedicated hybrid line) to be sold with its "base" version (called eAssistTM) having a hybrid powertrain. The V6 version sells for the same price ($30,620, delivered).
What impressed me was how GM engineers took last year's 4-cylinder engine and integrated a hybrid drive and battery, along with a new 6-speed automatic transmission, to produce an economical and smooth functioning package. A motor/generator replaces the conventional alternator and also functions as both a regenerative brake to charge the battery pack and a start/stop motor to allow shutting down the internal combustion engine when stopped in traffic. The motor/generator links to the engine/transmission via a 7-groove mechanical belt design to be under tension in either direction (thus dual tensioners) during application of electrical power or regenerative braking.
The motor/generator is liquid cooled and produces 15 hp, with 110 ft-lb (150 Nm) of torque to crank the engine in start/stop operation and 79 ft-lb (107 Nm) for assist at launch, on grades, and for highway acceleration. For initial start on a day's drive, there is a conventional 12V battery and starter motor.
The 115V, 0.5 kWh Li-ion battery pack consists of 32 cells the size of Red Bull cans and weighs 65 lb (29 kg)—about half the size of other hybrid car packs. The pack and control electronics sit over the rear axle, and, even with its fan and cooling air ducting, is small enough to allow clearance for a usable pass-through to the passenger cabin, about 16 inches wide.
Warranty period for the eAssist system is eight years or 100,000 miles, with the motor/generator belt specified for a 75,000 mile service interval.
According to Al Houtman, GM vehicle performance manager for front wheel drive hybrid programs, the hybrid system electrical management algorithms are based on those developed for the Chevy Volt. Operation is optimized to use the motor/generator augmentation for "torque smoothing" and to allow the internal combustion engine (2.41L, 182 hp, and 172 ft-lb torque) to run near its most efficient point as well as maintain battery state of charge.
Engine control architecture also implements a deceleration fuel cutoff regimen to further improve fuel economy. The result is U.S. EPA mileage ratings of 25 mpg (city) and 36 mpg (highway) using regular gas, improvements over last year's 4-cylinder model of 32 and 20%, respectively. (The V6 LaCrosse comes in at 17 mpg (city) and 27 mpg (highway) with its 303 hp.)
Earlier this week, this editor and fellow members of the New England Motor Press Association were given a detailed preview of the new LaCrosse—which significantly is the first car model (other than a dedicated hybrid line) to be sold with its "base" version (called eAssistTM) having a hybrid powertrain. The V6 version sells for the same price ($30,620, delivered).
What impressed me was how GM engineers took last year's 4-cylinder engine and integrated a hybrid drive and battery, along with a new 6-speed automatic transmission, to produce an economical and smooth functioning package. A motor/generator replaces the conventional alternator and also functions as both a regenerative brake to charge the battery pack and a start/stop motor to allow shutting down the internal combustion engine when stopped in traffic. The motor/generator links to the engine/transmission via a 7-groove mechanical belt design to be under tension in either direction (thus dual tensioners) during application of electrical power or regenerative braking.
The motor/generator is liquid cooled and produces 15 hp, with 110 ft-lb (150 Nm) of torque to crank the engine in start/stop operation and 79 ft-lb (107 Nm) for assist at launch, on grades, and for highway acceleration. For initial start on a day's drive, there is a conventional 12V battery and starter motor.
The 115V, 0.5 kWh Li-ion battery pack consists of 32 cells the size of Red Bull cans and weighs 65 lb (29 kg)—about half the size of other hybrid car packs. The pack and control electronics sit over the rear axle, and, even with its fan and cooling air ducting, is small enough to allow clearance for a usable pass-through to the passenger cabin, about 16 inches wide.
Warranty period for the eAssist system is eight years or 100,000 miles, with the motor/generator belt specified for a 75,000 mile service interval.
According to Al Houtman, GM vehicle performance manager for front wheel drive hybrid programs, the hybrid system electrical management algorithms are based on those developed for the Chevy Volt. Operation is optimized to use the motor/generator augmentation for "torque smoothing" and to allow the internal combustion engine (2.41L, 182 hp, and 172 ft-lb torque) to run near its most efficient point as well as maintain battery state of charge.
Engine control architecture also implements a deceleration fuel cutoff regimen to further improve fuel economy. The result is U.S. EPA mileage ratings of 25 mpg (city) and 36 mpg (highway) using regular gas, improvements over last year's 4-cylinder model of 32 and 20%, respectively. (The V6 LaCrosse comes in at 17 mpg (city) and 27 mpg (highway) with its 303 hp.)
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10/9/2011 1:05 PM EDT
Such complexity for such minimal results. I remember my 1989 Ford Festiva got 50 mpg regularly with just a manual clutch, an old-fashioned carburetor, and hand-adjusted distributor points. Interestingly, Ford would only admit to 36 mpg for that model, but I've never heard of anyone getting less than 48 mpg on the 1989 Festiva. When I bought it, there was only one of them at the dealership. The dealer never got any others, as far as I knew, only that one. It was almost as if Ford didn't want to sell these cars. So now car makers are coming out with Commando Cody, rocket-science cars with Lithium-ion batteries and special control electronics, and I have to laugh. If car makers started making something like the 1989 Ford Festiva again, they'd save a lot of wasted development time, save gas, and satisfy a lot of buyers.
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cbbear
10/13/2011 9:26 AM EDT
That was a Mazda design sold under Ford brand.
Royalties and internal competition with Ford's own brands might have been reasons for the poor marketing.
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Bert22306
10/10/2011 3:28 PM EDT
I think the best idea is to ignore marketing hype and catchy marketing names. This Buick is essntially the same car as yesterday's Saturn Aura Hybrid. Which means, mild hybrid, where the electric motor supplies primarily the start/stop feature, some minor amount of regenerative braking, and a short term, transient amount of torque boost when acelerating, to help out the otherwise anemic 4 cylinder engine.
The difference between this car and the Chevy Volt, IMO, is a matter of degree. The Volt has a massive battery pack, but it too is ultimately a hybrid. Which means, you cannot lift out the gasoline engine from the Volt and drop in a hydrogen fuel cell, without losing performance. It too depends on a mechanical linkage between gasoline engine and drivetrain.
And sure, the more battery you have, the less you rely on the gasoline engine when the gasoline engine is operating in an inefficient range.
Those interested in reality, vs marketing hype, ought to read the aricle comparing the Chevy Volt to the Chevy Cruze, in this month's Car and Driver magazine. Same basic car, but the Volt is saddled with two drivetrains. To make a long story short, the result in that comparison was also predictable. In city driving, the Volt did better. On the open road, the Cruze did better.
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Rick DeMeis
10/11/2011 2:22 PM EDT
Here is the take we did earlier on the Volt: http://eetimes.com/design/automotive-design/4218443/Driving-Impressions--Chevy-Volt?Ecosystem=automotive-design
And on the Chevy Cruze:
http://eetimes.com/electronics-blogs/pop-blog/4216290/Who-needs-a-hybrid-?Ecosystem=automotive-design
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Bert22306
10/11/2011 4:36 PM EDT
Yes, they were very informative, and I read the both.
But the title of this article is "When is a hybrid not a hybrid?" And given that a similar question arose of whether the Volt was an electric car or a hybrid, I thought it was time to bring all of these topics together.
A hybrid is a car with dual drivetrains - one electric and one mechanical. Both this Buick and the Volt fit that description, even though the Volt gives more emphasis on electric storage. And even though GM marketing types did their level best to obfuscate that. Bottom line: there is definitely a mechanical linkage between engine and wheels in the Volt, which comes into play when high horsepower is required (like freeway driving).
The Car and Driver article deliberately compared the Volt and the Cruze Eco under the same diving conditions. Given that the Cruze Eco incorporates most of the energy saving features of the Volt, and is built on exactly the same platform, I think that direct comparison was just what the doctor ordered. And the results were as I had expected (and commented on your Cruze Eco article).
I guess what I'm saying is, GM marketing can play word games, but we are engineers. We can happily ignore marketing terms and ferret out the truth.
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Eric Verhulst_Altreonic
10/12/2011 6:05 AM EDT
Sometimes I think technology has stalled. Porche had electric drives (hub motors in the wheel) 100 years ago with range and mileage almost the same as today. What happened the last 100 years? OK, we got more comfort and ease-of-use, etc. but you would expect a lot more over a 100 years time period. Even public transport (trains and busses) has not made a serious jump (with the exception of high speed trains). It's time for a radical rethinking of the established solutions.
KISS: Keep it Simple but Smart.
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1Sparky
10/12/2011 1:41 PM EDT
I think the Marketeers are a lot like Hydrologists: they're scared of electricity! I guess the Marketeers are guessing Joe Public is also scared of electricity...so lets call it something else...Me? I'm a sparky and I'm scared of Gasoline!
Funny the GM driveline looks a lot like my Golf Cart with electric start; gee those GM engineers are Brilliant, eh!
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kkersey
10/12/2011 1:56 PM EDT
I agree with Bert's comments. There are difficult and sometimes subtle tradeoffs in these various approaches. For example - if you want to capture more regenerative braking energy - you will need an electrical drivetrain capable of high horsepower (in braking mode)...which costs a lot. The main reason that adoption of hybrids has actually SLOWED in the last year is that the added cost of hybrids doesn't really pay-off in a reasonable time vs. just buying one of the new high-efficiency conventional cars (~40MPG EPA). In a hybrid, not only does the electric powertrain allow start-stop (helps only in urban cycle) and allows the gas engine to operate in higher efficiency modes - it allows that engine to be downsized and/or converted to atkinson cycle (larger expansion ratio), which has less horsepower but higher efficiency. The needed power for accelerating at an acceptable rate is then made-up by the electric powertrain. Efficiency and reduction of fossil fuel usage is important - but the public demands that it be cost-effective too!
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