|The Buick LaCrosse Eco-Hybrid.|
The Buick LaCrosse Eco-Hybrid (earlier post), is making its auto show debut at the 2008 Beijing International Automotive Exhibition (Auto China Beijing). Introduced by Shanghai GM in January, the LaCrosse uses the GM Hybrid System (a mild-hybrid, belt-alternator-starter system) to deliver a 15% improvement in fuel consumption: 8.3 L/100km (28.3 mpg US), compared with 9.8 L/100km (24 mpg US) for the non-hybrid version.
GM also introduced the Cadillac Escalade 2-Mode Hybrid for the first time in China at the event. The company plans to begin sales of the 2-Mode luxury full-size SUV there in 2009.
The LaCrosse Eco-Hybrid represents the first application of the GM Hybrid System in Asia Pacific and will be available in China before the opening of the Beijing Olympics this summer.
The hybrid is powered by GM’s Ecotec D-VVT 2.4-liter all-aluminum engine. Hybrid functions include start-top; early fuel shut off during deceleration; regenerative braking; and intelligent battery charging.
At the show, Joseph Liu, GM China’s vice president for sales, said that the company did not expect to see a very high volume of sales of the hybrid model in a short period of time. “But we bring this technology to help China support sustainable growth and bring consumers in that direction,” he said.
Escalade 2-Mode. Fitted out with a 2-Mode powertrain similar to that in the Tahoe and Yukon, the Escalade hybrid can achieve a 50% reduction in fuel consumption in city driving when compared to non-hybrid Escalade models.
The powertrain combines a 6.0-liter V-8 featuring late-intake valve closing (LIVC) technology to enable a modified Atkinson-cycle combustion process and Active Fuel Management (cylinder deactivation) with the 2-Mode advanced electrically variable transmission (EVT) and 300-volt NiMH Energy Storage System (ESS).
The EVT is an assemblage of two 60 kW electric motors, three planetary gearsets and four traditional hydraulic wet clutches. This arrangement allows continuously variable operation, as well as providing four fixed gear ratios (with operation comparable to that of a standard electronically controlled automatic transmission). (Earlier post.)
A Hybrid Optimizing System (HOS) constantly receives torque-based data from the powertrain and other vehicle systems, and then determines the most efficient means of propelling the vehicle—either via electric power, gasoline engine power or a combination of the two. The EVT is like having two transmissions in one—continuously variable drive for light-load conditions and fixed-ratio drive for high-load situations.
All functions of the EVT are controlled by the HOS, which constantly searches for the optimal transmission operation (using either variable or fixed ratios) to meet current operating conditions.
AFM enables the V-8 engine to seamlessly shut off half of its cylinders when less power is needed, such as during highway cruising. This new hybrid system not only enables the Escalade Hybrid to drive low speeds on electricity alone, it also allows the 6.0-liter V-8 engine to operate in its more economical four-cylinder mode for longer periods.
The HOS also bases its decisions on allowing the Vortec 6.0L V-8 to take full advantage of its Active Fuel Management system and, because of an equivalent 30-horsepower (22 kW) boost of electric power, remain in V-4 mode as long as possible for maximum fuel economy.
The 2-Mode hybrid features a new exhaust system and resonator specially tuned for the 6.0-liter LIVC engine’s Active Fuel Management operation to ensure comfortable interior acoustics and a pleasant exhaust note during both V-4 and V-8 operation.
An electrically driven, 300-volt air conditioning compressor reduces vibration and allows the HVAC system to cool the passenger compartment even when the gasoline engine is shut off. It includes a standard tri-zone climate system. (The Escalade seats 8 passengers.)
Electrically driven, 42-volt variable-assist power steering reduces vibration and provides up to a 0.5-mpg fuel economy improvement by reducing parasitic losses common in belt-driven hydraulic systems.
The Energy Storage System cooling system’s internal fan is tuned to be quiet at low vehicle speeds, when the fan could more easily be heard by the occupants.