While the Volt and its E-Flex architecture has been drawing most of the attention at GM these days, the engineers at GM Powertrain have been quietly updating the belt-driven motor/alternator system first introduced in 2006 on the Saturn Vue Green Line. Scheduled for production in late 2009, it promises more power and voltage than the current system, increased regenerative braking capability, more electrical boost throughout the drive cycle, greater fuel efficiency, better vehicle acceleration, and easier integration into GM’s global vehicle portfolio.
“The replacement of the nickel-metal hydride battery with a lithium-ion unit gives us increased electrical power that will enable us to use the hybrid system in a wide range of global powertrains, including downsized turbo engines, biofuel engines, and diesels,” says Dan Hancock, v.p. GM Powertrain Global Engineering. It may not stop there. “If the federal CAFE rules are split such that they allow California to go forward with its 40-mpg fleet average,” says Steve Poulos, chief engineer, GM Hybrid Systems, “this effect can be magnified to the point that we replace a 2.4-liter naturally aspirated non-hybrid engine with a 1.4- to 1.6-liter turbocharged direct-injection hybrid powertrain.” In addition, says Poulos, this system can be used on rear-drive vehicles and engines up to and including V8s, making it readily adaptable to a variety of GM products.
Compared to the current system, the lithium-ion battery pack from Hitachi Vehicle Energy, Ltd. (Ibaraki, Japan; www.hitachi.com is about 24% smaller, 40% lighter, and 33% more powerful. According to Poulus, “it’s a bit larger than a 12-pack of Coke.” Meanwhile the new motor/generator unit fits in the same package space, produces 15 kW of power instead of the previous unit’s 5 kW, and has a highly integrated design that results in a lower piece cost. GM is cagey about ultimate volumes for the system, saying only that it could sell more than 100,000 units per year soon after its introduction.—CAS.