More On Ford's New Hybrids: Advances Explained, Ford Technology Stressed
By John O'Dell October 31, 2008
Fighting the long-held perception that much of the technology in their company's first "full"-hybrid system for the Escape hybrid SUV was bought or licensed from Toyota, executives and engineers at Ford were crystal-clear during this week's media preview of the all-new hybrid architecture for the company's upcoming Ford Fusion and Mercury Milan hybrid sedans: Everything, they said, was designed by Ford in North America.
The new hybrid system is "100 percent Ford technology; 100 percent Ford design, invented right here in North America," said Nancy Gioia, Ford Motor Co.'s director of sustainable mobility technologies and hybrids. She and other engineers say every major component was developed under Ford engineering.
In detailing the key components, engineers said they stressed an interdisciplinary approach that helped optimize all components for maximum system efficiency. The process developed several intriguing new components and advances, they said.
Perhaps most impressive is the nickel-metal hydride battery pack, put together by Delphi Corp. using individual cells supplied by Sanyo.
The latest NiMH chemistry enabled Ford to use 17 percent fewer cells (208) in the pack and to reduce total system voltage to 275 volts from the previous 330 volts because cell power has been increased by 20 percent.
The pack nonetheless is 30 percent smaller and 23 percent lighter that the nickel-metal hydride pack used in the automaker's Ford Escape and Mercury Mariner hybrid SUVs.
The new battery chemistry also means the batteries can deliver their utmost at higher temperatures. As a result, engineers were able to ditch the previous system's dedicated cooling system - the battery pack now will be cooled with cabin air.
Ford engineers tell Green Car Advisor that losing the dedicated cooling architecture delivered a weight savings on the order of 15 pounds. That's on top of the enormous 50 pounds. chopped from the battery pack itself.
The system's more-powerful 93-kilowatt drive motor, higher-capacity generator (73 kW vs. 45 kW) and "power-split device" (CVT for lack of a better term) all are housed in one monolithic transaxle casting (top illustration). There is no increase in size or weight, despite the higher-power components.
A variable-voltage converter allows the motor to be operated most of the time with a lower, more-efficient voltage, despite the fact the motor itself has increased power capacity.
When full power is necessary, the variable-voltage converter boosts the system voltage to address the additional power required by the motor.
Engineers say the main advantage from the larger motor isn't the increased power to drive the wheels; it is the ability to run purely on electric power at much higher speed - up to 47 mph - than was available in the old system, which was good for only about 25 mph.
They say the huskier motor provides another advantage: it can absorb more braking energy from the regenerative braking, and absorb that energy more quickly.
The higher-capacity generator, meanwhile, facilitates blending drive power from the electric motor and the 2.5-liter, 4-cylinder gasoline engine.
That's important for the reduced levels of noise, vibration and harshness engineers insisted upon, and for inconspicuous transitions, between internal-combustion and electric propulsion.
A final improvement: The brake pedal incorporates an all-new (and rather complicated-looking) "simulator" that engineers claim will markedly improve the artificial and wooden feel typical of many braking systems incorporating regenerative function - particularly at initial brake "tip in."
Ford claims that the innovation replaces antiseptic hybrid braking feel with "premium brake-pedal feel."
Bill Visnic, Senior Editor, Edmunds AutoObserver
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