Peugeot and Michelin Say the Prize is in the Package
By Martin Schwoerer
Concept cars are often of limited interest because they tend to resemble the saying from post-war Britain: If we had ham, we could make ham and eggs, if we had eggs.
In that vein, many concepts that are being shown at the current, bi-annual international Frankfurt show seem to be saying: "if we had batteries, we'd have a viable electric car, if we could make a lightweight car".
So it's always a welcome change when a car maker employs a realistic technology that seems to offer a really new automotive perspective.
The first impression of Peugeot in Frankfurt is not good. They are showcasing the iOn, which is no more than a badge-engineered Mitsubishi i-MiEV. It could be considered commendable if the caption describing the iOn didn't say "Peugeot is a pioneer and world-wide leading maker of electric vehicles." That's not what you should claim when you're just slapping your badges on somebody else's car.
But Peugeot presented another electric vehicle, the miniscule BB1 (pictured below). You could call it an amusingly bizarre study in the tradition of the Zündapp Janus, best known as a car impossible to tell whether it was going forwards or backwards.
However, the Peugeot has acceptable space for four persons in a package as small as a Smart (actually, only 2.5 meters / 8.2 feet length). This is because the BB1 uses hub motor technology. In other words, it has its electric motors enclosed in the rear wheels.
Thus, no components are required to be under the hood. Indeed, there is no hood -- the batteries of this EV are under the floor.
Michelin, best known as a maker of tires, has been working on in-hub motor technology for years now, and already has a fleet of hub-engined cars -- the Heuliez Will -- undergoing log-term tests.
The Will employs the most advanced version of Michelin's "active wheel" system, which not only includes a motor and braking systems, but also active suspension. The BB1 in contrast has a simpler system which goes without active suspension.
Monsieur Pierre Varenne, Directeur at Michelin Recherche et Technique SA, kindly took the time to answer my questions about the differences between various in-hub motor systems, and their respective advantages and disavantages.
Q: Why does the BB1 do without active suspension?
A: Active suspension offers a leap forward in terms of handling and comfort characteristics, but for a city car as the BB1 is, the packaging advantage of a in-hub engine is the most important aspect -- especially when you can provide it at a lower price. Another advantage of the in-hub approach is a reduction in mass. There is no drive train, and we were able to shrink the electric motor.
Q: I imagine that in-hub motors increase unsprung weight by a considerable degree.
A: Actually, there is no real increase in unsprung weight. The total unsprung weight of the "simple" in-hub system is 30KG per wheel. For the version with active suspension, it is 35KG. This is a real advancement in comparison to other in-hub motor systems.
Q: A few months ago, I spoke with a Swiss engineer who works on electric car motors. He claimed an in-hub system generally would have thermal problems.
A: Well, perhaps he would think differently if he worked for Michelin! We have no thermal problems in normal usage. Of course, if we were talking about a race car, then an in-hub motor might not be such a good idea. But please keep in mind that the Venturi Volage has four in-hub motors, each of which have a power rating of 100 kW. In other words, it's a powerful, special car, and yet Venturi has no problems with brake fading or motor overheating. If the wheel is 15" or larger, enough air can get to the various components.
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