Tom Stephens, GMís group VP of powertrains, details GMís hybrid powertrain strategy at the 2003 NAIAS.At the 2003 North American International Auto Show in Detroit, GM dropped a bomb on env" />

Issue: Feb 2003


Even Stephens



GM powertain czar Tom Stephensí three hybrid strategy evens the score with Honda, Toyota and Ford.

by Gerry Kobe






 
Tom Stephens, GMís group VP of powertrains, details GMís hybrid powertrain strategy at the 2003 NAIAS.
At the 2003 North American International Auto Show in Detroit, GM dropped a bomb on environmental skeptics by announcing that it would field three hybrid gas/electric powertrains beginning in 2004. The systems will be offered in volumes of up to one million units annually if customer demand requires. GM said it expects at least 7,000 hybrid SUVs will be sold in the first year, making good on its promise to target low mileage/high volume vehicles to achieve maximum environmental benefit. AI editor Gerry Kobe spoke with Tom Stephens, GMís group vice president of powertrains about the specifics of GMís decision.

Q. After being criticized for not having hybrid technology, what prompted GM to introduce not one but three hybrid systems?
A.
Hybrids are a bridge to our long-term strategy, which is fuel cells. And naturally you want to get the cost down for that strategy. So the first thing you want to do is break that longterm plan into its major systems. Then you want to figure out what you need to learn on those major systems to get cost out of the design as well as manufacturing the components so you can get the cost out of the process.

Q. How much do hybrids and fuel cell vehicles actually share?
A.
If you look at the fuel cell, obviously you have to do all those things on the fuel cell stack by itself, but what about the electric motors that are in there? What about the electronics that make it all work together? Well, you can pick all of that knowledge up on a hybrid. So we decided to start working on the hybrid, knowing that it will in fact help bridge us to the fuel cell strategy. You still have the rest to do but itís a nice start.

Q. So are the hybrids a good value in and of themselves or are they just a stepping stone to fuel cell vehicles?
A.
GMís hybrids will be very effective. Some of the technologies we have, like displacement on demand (DOD), is ideal to mate up with a flywheel alternator system. Any hybrid powertrain tends to improve the city mileage more than the highway economy, but DOD tends to improve highway better than city. You put them together and all of a sudden its like a super position, you have great city and highway.

Q. How is that different from other hybrids like those from Honda and Toyota?
A.
If you look at all hybrids out there today, especially the Toyota hybrids, all of them are designed for congested stop and go driving. And I think you can read that to be Tokyo. And they do a good job for that kind of driving. But if you look at America, we only drive 40 percent of the time in city traffic, the rest is highway driving. So it would be better to have a system that improves both city and highway and we have done that. So itís really an American solution.

Q. Having driven the Japanese hybrids Iím not sure U.S. drivers will embrace the lower power output of these vehicles. Have you found a way around that?
A.
Again, that is where DOD comes in. Americans like the power they get now. They still like to put their families in the truck. They like to get groceries. They like to pull their boat and with DOD, the power is there when you need it and off when you donít. Itís a no compromise American solution. Doesnít compromise performance in any way and youíve got utility. So we donít just have a hybrid system, we have a hybrid system designed for the way we drive in the U.S. Thatís why we feel it is a good bridging strategy toward our long-term solution, which is fuel cells.

Q. Why three approaches to hybrids? Why not just one?
A.
We have a mid-, near- and long-term strategy. The companies that have already done hybrids have taken a small slice or a sliver of the market. We chose not to do that. We thought, why donít we try to look at the entire portfolio of the market and do it by choosing three of our highest volume architectures. The first is our full-size truck and that is our highest volume going. That volume gives it a lot of leverage and that is why we are introducing it later this year to commercial fleets and then later to retail, two pickups, the Silverado and Sierra with a hybrid option that improves economy 10 to 12 percent. By the way, we are going to follow that in 2007 with this displacement on demand technology and take the 10 to 12 percent to 15 to 20 percent from todayís level.

Q. What other platforms did you choose for hybrids?
A.
Next was Theta architectures, mid-size SUVs like the Saturn VUE or new Chevy Equinox and after that we will do the mid-size platform called Epsilon. We will do the Malibu first and then others to follow.

Q. And each will take a different approach?
A.
We will have three levels of hybridization. Everything from the flywheel alternator on the truck to the belt alternator starter that will go on some of the small FWD cars and small intermediate cars as well as well as FWD sport /utility vehicles. And then we have another one that is a dual electric motor system that has twin electric motors that control a 6-speed manual transmission and shifts automatically. That system will be on a mid-size SUV like the VUE and can improve mileage by 50 percent.

Q. Why not just have one system across all of those platforms?
A.
It allows us to mix and match. We cover the entire spectrum, not only in different models, but we cover that with different complexity of systems. They represent a minimum, midlevel and maximum hybridization. We have to see what is popular with our customers. And if something is well received we know to bring up our volume or add more models. Or, if it doesnít have any interest, we can adjust down as well.

Q. Are all of the gains you mention strictly from the powertrain or are there other factors?
A.
Of the 50 percent improvement you can get, the hybridization part of the equation might be 30 to 35 percent and the rest will come from aero, lower rolling resistance tires, electric components like brakes and electric power steering. It even takes the AC and runs it belt driven off the electric motors. But all of that points to where our end game will be which is fuel cells in the future.

We decided to start working on the hybrid, knowing that it will in fact help bridge us to the fuel cell strategy.

Q. Do you think people care about fuel mileage with gas prices as low as they are?
A.
In the U.S. probably not. I think people still would like to have high fuel economy but I think they donít want to pay for it because the value equation isnít there. Thatís why I think with this kind of technology, if it is important from a national perspective, that we conserve fuel and reduce dependence on foreign oil, then we have to work together and come up with a value for the consumer. It has to represent a value or they wonít buy it and if they donít buy it, it doesnít do us any good to develop it.

Q. How will you proceed when you start getting real-world feedback on your new systems?
A.
Well, Iíll make things up, but letís say that it is popular to have the version that has an electronic power take-off with commercial guys who buy work trucks who want them to power skill saws and planers and drills and things at the work site. And letís say it is also popular with campers or people that want to go tailgating at football games on the weekend. If that happens, we can make a lot of those.

Q. And what if itís not accepted at all?
A.
Remember, we have multiple approaches. On the other end of the spectrum, letís say somebody likes performance and they are willing to pay for performance. With our twin motor mid-size SUV we currently have a 125 hp 2.0L 4-cylinder engine and two 20 kW motors, thatís 175 hp. We could just change the engine and use a 2.4L engine at say 170 or 180 hp and combined with the electric motors bring the horsepower up to 230 or 240 and all of a sudden we have a performance vehicle that also gets great economy. So depending on what we see, I can mix and match propulsion systems and make some pretty neat things.

Q. Are the components of the system inherently expensive or can economies of scale bring prices down?
A.
Inherently, when you have two propulsion systems it is going to be expensive. Volume does wonders for getting prices down but prices for hybrids are high. Much higher than you would probably anticipate. And the volume will get it down but regardless there is still a lot of content. That being the case, we will get the cost down as low as it can be and once we get it down the other thing we have to work on is how low can we get the end product down , which is the fuel cell.

Q. What kind of volumes make these components affordable?
A.
You canít know that until you know what the customer is willing to pay, but what we can control is picking large volume architectures and then not going willy nilly with component sets but picking three that satisfy everything. And then mixing and matching and all of a sudden you have a lot of models using the same components set and by definition, your volume per component set is going to be high.

Q. Will you ever get to the point where a hybrid option is available on any model the way air conditioning is now?
A.
We are already thinking that way when we do the high volume architectures. On our full size truck for example, we already laid out the space for the hybrid system on our pickups and SUVs and if you looked at the number of models of those vehicles, it is very significant. Weíve laid out space already for the option. Same on Epsilon. We did that thinking that if people do want this we can take new models off the same architecture so they are already packaged and ready to go.

We cover the entire spectrum, not only in different models, but we cover that with different complexity of systems.

Q. How much space do you have to protect for with these systems?
A.
The space needed varies from system to system. There is not much mass or packaging difficulty for the belt alternator system. With the dual motor system ó such as on the VUE ó that are actually packaged inside a transaxle, it is significant. Thereís a lot associated with that. Hopefully we will get the complexity and size down and we do it for the next generation. Iíve seen a lot of that where you get smarter each time.

Q. Howís the durability of these systems?
A.
We havenít had durability, reliability or quality issues to be honest with you. And high volume helps electronics because it tends to make them better. In electronics, it has been my experience that its not necessarily a situation where you can test to failure, itís more what kind of variation you have in the production of those components and the higher the volume production the more robust system you can put in place.

Q. As you move toward fuel cell cars will the electronics become even more complicated?
A.
If you think about control systems and control algorithms, you have a tougher time controlling something that has an internal combustion engine, two electric motors and a manual transmission. Add to that the drive-bywire and brake-by-wire and trying to get all that stuff to work together. It seems to me that itís far more difficult than if you had just electric motors and a fuel cell generating electricity and then some kind of drive by wire.

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