High praise for hybrids
Prius engineer: We must expand technology, preserve brand image
Toyota Prius chief engineer Satoshi Osigo
As chief engineer for the Toyota Prius, Satoshi Ogiso has strong opinions about the value of hybrid technology and about preserving the brand strength of the world's leading alternative-powertrain vehicle.
Ogiso has worked on Toyota's Prius family of hybrids from the original hatchback to the Prius V wagon launched last fall, and on the Prius C and plug-in hybrid that is rolling out this spring.
Ogiso spoke with Enterprise Editor Dave Guilford at the recent Geneva auto show.
Q: If you look at the range of powertrains from combustion engine to fuel cell, what is most practical?
A: At this moment, I think that from the practicality point of view, expanding hybrids -- regular hybrids -- is very important. Some companies say that the conventional gasoline engine will be improved more and more. But that also means that an improved gasoline engine together with hybrid also goes better.
On the plug-in hybrid Prius, your electric-drive range is about 25 kilometers, or 15.5 miles. The Chevrolet Volt has a range of about 35 miles, but the trade-off is a bigger, heavier battery. Was part of your thinking to reduce battery weight and cost?
We decided [on] that, because to optimize the battery size and weight is important for the plug-in hybrid. So our Prius plug-in hybrid electric vehicle range is 25 kilometers, but at the same time, no compromise, no trade-off happened in the interior space, including the luggage space. That is a little bit different from the Chevy Volt.
Also, what is very important is fuel economy in the hybrid mode. Our hybrid mode fuel efficiency is very, very good. For the United States, hybrid-mode mpg is 50. That is greatly different from the Volt.
Has working with Tesla on an electric drivetrain made you think about using lithium ion batteries? Or do you anticipate using nickel-metal hydride for quite some time?
At this moment, the nickel-metal hydride still has a good performance, especially for the cost. So we will use both nickel-metal hydride batteries and lithium ion batteries. For the regular Prius we use nickel-metal hydride because of the cost point of view. And, of course, the Prius plug-in has the lithium ion battery.
Do you anticipate any dedicated hybrid nameplates within Toyota that would be branded other than Prius?
This is my opinion, not a Toyota Motor Corp. announcement. But my opinion is that we should not expand hybrid-dedicated vehicles so much because hybrid-dedicated is not the key concept. Of course, Prius is hybrid-dedicated, but Prius is the high-technology car and fuel-efficient [car]. So probably the Prius family is the only group of dedicated hybrids that we need.
I personally think that Prius has a strong brand image, not only by [being] a hybrid model, but by iconic shape, dynamic performance, high-tech features in the interior, roomier interior -- this combination is the key for the Prius brand. Sometimes some persons, even in Toyota, misunderstand that if someone made a dedicated model, [it] easily could be as successful as Prius was.
Some companies favor using the different components of hybrid drive -- stop-start, regenerative braking, electric power steering and so forth -- selectively. Do you see that as a viable alternative?
For our full hybrid system, Hybrid Synergy Drive, cost performance is similar to the mild hybrid, or sometimes better than mild hybrid. One strong point for Hybrid Synergy Drive is that the system does not have the mechanical transmission. Our hybrid system only has the two motor generators and the power split device, that's all. So the timing of the power electronics devices is not expensive.
Based on our current production technology, our two-motor system has better performance compared to the one-motor mild hybrid system. And, of course, the fuel efficiency performance is much better than a mild hybrid.
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