Cleanse your mind of what you think you know about the Chevy Volt. It is not just an electric car. It does not operate as implied by GM for the past three years. Now that production has begun and customer deliveries are about to commence, the secrets are out. A true explanation of exactly what makes the wheels turn can finally be told.
According to Larry Nitz, GM's executive director of electric and hybrid powertrain engineering, this bit of bait and switch was necessary to safeguard the intellectual properties necessary to make the Volt a true technological leap forward. During the past three-plus year of engineering and development, GM applied for several patents to protect many small and large inventions. Those patents have been issued and Nitz is finally comfortable speaking frankly about what's under Volt's hood.
The Volt concept car, which debuted at the 2007 North American International Auto Show in Detroit, had an AC motor connected to and permanently driving the front wheels. A turbocharged 1.0-liter 3-cylinder gasoline engine powered a generator which supplied current to the drive motor, but only after the onboard lithium ion battery pack was depleted. This system, which GM called E-Flex, provided an electrical connection between the two portions of the powertrain but no mechanical connection.
When the evolution of the promising concept into a practical production car began in earnest, GM engineers immediately ventured beyond E-Flex. Maintaining a strong emphasis on electric propulsion, they added parts and increased the role of the gasoline engine. The finished product-now called Voltec--is much closer to a Toyota Prius than a Nissan Leaf. Volt is the first extended-range electric car, as advertised, and more.
Secret Gears and Clutches!
1. The previously undisclosed heart of the matter is an automatic transmission consisting of one planetary gear set and three electronically controlled, hydraulically activated multi-plate clutches. This ingenious transmission efficiently blends electrical and mechanical attributes to drive the wheels with utmost efficiency. All Volt powertrain components-two electric motor-generators, the 1.4-liter 84-hp gasoline engine, the aforementioned transmission, and a final-drive differential-are bolted together in a single unit to save space and weight and to optimize NVH characteristics.