Out of this, the GM team selected several systems for more intensive study and comparison with two benchmark systems from other OEMs. About half of these were chosen for energy modeling in both EV and extended range operation, using a simulation tool developed by GMR&D. A team from GM Research and Development (GMR&D), Advanced Engineering, and Product Engineering examined more than 50 types of electric and hybrid propulsion systems to find the best type for the second-generation Volt. GM took a blank-sheet approach to designing the second-generation system. Transaxle configuration and operating modes. The range-extending engine is a 1.5-liter four-cylinder, naturally-aspirated direct-injection spark-ignition engine with sufficient power to continue normal driving after most of the battery energy has been depleted by EV driving or during conditions when available battery power is low because of extreme temperatures. The drive unit contains two newly developed electric motor-generators for propelling the vehicle and other duties power electronics to supply and control them a system of gears, clutches, and hydraulic controls to combine and deliver the mechanical power from the motor-generators and the engine and an electric oil pump. The major components of the propulsion system are the battery pack, the drive unit, and the engine. Whether the vehicle is operating in EV or range extended mode. Smooth, unobtrusive, power on demand regardless of.Increased charge sustaining fuel economy.(A fifth paper presented at the World Congress assessed one year of in-use operating data from first-generation Chevrolet Volt and projected the performance of the second generation.)įor the second-generation, GM wanted to enhance the electric performance of the Volt. A GM analysis of vehicle data collected from first generation found that Volt vehicles were driven more than half a billion miles in North America from October 2013 through September 2014, and that 74% of the miles were all-electric. Consider the Volt a well-engineered first step on the path to electrified vehicles.In designing the second-generation system, GM engineers built on the knowledge and data gained from the first-generation Volt. But of course, those two powertrains are why the Volt can be a primary vehicle that doesn't ask the owner to compromise driving cycles like a pure EV. As for the rather unremarkable fuel economy, it's useful to remember that the Volt carries two powertrains-electric and gas-and thus suffers a weight penalty that effects overall efficiency. Except for some of the materials, the interior cocoon fits a $41,000 car, which in practice drops to $33,500 after the $7500 federal EV subsidy. The Bottom LineĪfter our three days with the Volt, we're certain of a few things: One, the car is a well-engineered piece that integrates the various powertrain components with a refinement we didn't expect. If we factor in the distance traveled on the battery's energy the fuel economy jumps to 37.5 mpg city and 38.15 mpg highway. In the city, we recorded 31.67 mpg and achieved 36.0 mpg on the highway. In other words, we computed the fuel economy after the battery was depleted, both on our city loop and the highway trip. In addition to measuring EV range, we also recorded the fuel use when the car was in its "charge sustaining" mode. Still the Volt's EV range beat that first day when we were really trying: 33 miles. Also, we set the cruise at a typically brisk Michigan highway traffic speed-78 mph. Charge #3įinally, we drove the Volt for nearly 600 miles on the highway only, a tough test for any hybrid since there's no opportunity for brake regeneration. We must have recaptured more braking energy in the city streets than the previous day, because the Volt traveled 35 miles on just the battery. Charge #2įor the second charge, we stuck to city streets but operated the car normally, with the auto HVAC operating and without special driving techniques. Our hypermiling skill is clearly lacking: After 31 miles the engine kicked on. Our route meandered through Ann Arbor and the surrounding two-lane country roads. We turned off the climate control, which wasn't a problem since the outside temperature was roughly 55 degrees. It must have known of our usual lead-foot nature. The dash display said we had 48 miles of EV range, which dropped to 43 after the first quarter mile. After a 11-hour overnight charge using the cord stored in the cargo area and a 120-volt outlet in our garage (a 240-volt charger will sell for $490 before installation and will drop the recharge time by at least half), we set out to maximize EV range.
0 Comments
Leave a Reply. |