|The Chrysler hybrid SUVs being introduced at the LA Auto Show.|
Chrysler has introduced its first two hybrids on the market—the 2009 Chrysler Aspen and Dodge Durango HEMI Hybrid full-size SUVs—both based on the two-mode advanced hybrid system developed with General Motors and BMW.
Capable of towing 6,000 lbs., the new 5.7-liter HEMI Hybrids develop 385 hp (287 kW) and are expected to deliver an overall fuel economy improvement of more than 25%, including an improvement of nearly 40% in the city. By comparison, the gasoline-only 2008 Aspen with 5.7-liter engine has an EPA fuel economy rating of 13 mpg city, 19 mpg highway and 15 mpg combined.
The HEMI engine applied in the hybrid will continue to feature Chrysler’s MDS, which allows the engine to seamlessly alternate between four-cylinder mode when less power is needed and V-8 mode when more power is in demand. The two-mode hybrid system provides assistance from electric motors allowing the HEMI V-8 to remain in four-cylinder mode more often than without a hybrid powertrain, improving overall fuel economy.
Built at the Newark Assembly Plant in Delaware, the new 2009 Chrysler Aspen and Dodge Durango HEMI Hybrid vehicles arrive in showrooms in mid-2008.
The two-mode two-mode full hybrid system offers low- and high-speed electric continuously variable transmission (ECVT) modes (“two-mode”) and four fixed-gear ratios for high efficiency and power-handling capabilities. During the two ECVT modes, the system can use the electric motors for acceleration, improving fuel economy, or for regenerative braking to utilize energy that would normally be lost during braking or deceleration. The energy is stored in the batteries for later use.
The system’s two ECVT modes are optimized for city and highway driving. In the first mode—at low speed and with light loads—the vehicle can operate in three ways:
Electric power only
Engine power only
Any combination of engine and electric power
The second mode is used primarily at highway speeds. In addition to electric assist, the second mode provides full power from the 5.7-liter HEMI V8 when conditions demand it, such as when passing, pulling a trailer or climbing a steep grade.
A sophisticated controller determines when the vehicle should operate in the first or second mode. Input from the controller determines the necessary torque for the driving conditions and sends a corresponding command to the engine and electric motors. The engine and electric motors transfer torque to a series of gears in the transmission, which multiply torque similar to a conventional automatic transmission to propel the vehicle. Unlike conventional continuously variable transmissions, however, the two-mode full hybrid’s electrically controlled system uses no mechanical belts or bands. Shifts between the two modes are synchronous—meaning no engine speed changes are necessary for the mode shift to occur—resulting in seamless accelerations.
The 300-volt NiMH battery pack provides electric power for the system, and is designed to fit in the vehicle without compromising passenger space. A rectifier located under the vehicle’s hood converts AC to DC, to power conventional 12-volt accessories, such as interior lighting, climate control and the audio system.