With its new Escape HEV, Ford Motor Company is aiming for nothing less than the hybrid electric vehicle crown.

The Escape HEV will feature a new PowerSmart™ transaxle that will offer improved power, performance and fuel economy benefits compared to hybrid electric vehicles currently on the road. The system was developed by Ford and Aisin AW.

Escape HEV combines an electric motor and fuel-efficient four-cylinder gasoline engine. It is designed to be the most fuel-efficient sport utility on the planet when it debuts in 2003. This hybrid electric vehicle technology will also be available later in Europe under the Maverick name.

With regenerative braking and nearly instantaneous start-stop capability, the Escape HEV will be especially fuel efficient in the city, delivering nearly 40 miles per gallon in urban driving.The hybrid electric Escape willbe able to travel more than 500 miles on a single tank of gasoline. Yet the innovative hybrid powertrain will deliver acceleration performance similar to an Escape equipped with the 200 horsepower, V-6 gasoline engine.

The PowerSmart™ transaxle further improves performance by offering many of the benefits of a continuously variable transmission, including nearly seamless shifting. The driver uses a familiar floor shifter with selections for Park, Reverse, Neutral, Drive and Low, but virtually all of these functions operate differently. The point is that these functions are seamless to the driver, who operates the vehicle in a familiar, comfortable way.

While a few automakers have introduced small, relatively low-volume hybrid electric cars, Ford is introducing its first HEV in a family-sized sport utility to increase mass customer appeal. The hybrid electric powertrain also has been developed with additional applications and vehicles in mind to expand the potential impact of the environmentally responsible technology.

The PowerSmart ™ system incorporates technology developed by Volvo and Aisin AW for Volvo's Dual Hybrid Electric System for Increased Efficiency and Economy (DESIREE) program, which debuted at the Geneva Auto Show in 1999.

Aisin AW, based in Aichi Prefecture in central Japan, was honored as a Gold Award winner in the 2000 Ford World Excellence Awards for its performance as a long-time supplier.

How it Works

The PowerSmart™ transaxle case houses the traction motor and motor generator. The transaxle eliminates shifting, much like a continuously variable transmission, because it uses an electrical power loop in combination with a traditional mechanical planetary gear set to join the engine, motor and generator to the drive wheels.

The drive system combines a 65 kW permanent magnetic electric motor and 28kW generator with an Atkinson cycle variant of the Escape's Zetec four-cylinder engine. An electronic controller continuously adjusts the contributions of all of these power sources to maximize fuel efficiency. In addition, energy normally dissipated as heat during breaking is recaptured as electric energy and stored in the battery. This controller was developed through Ford's participation in the Partnership for a New Generation of Vehicles (PNGV) program.

The Atkinson cycle engine is up to 10 percent more efficient than a conventional four-stroke Otto cycle engine. The increase in efficiency is due to controlling pumping losses and optimizing the expansion ratio while maintaining a constant compression ratio.

The Atkinson cycle - also called the "five-stroke cycle" - works like this: intake, back-flow (partial expulsion to eliminate pumping losses), compression, expansion and exhaust. The combustion chamber volume is adapted to maintain a constant compression ratio to avoid knock while increasing the expansion ratio to optimize efficiency. Engineers convert the Zetec I-4 engine to an Atkinson cycle by changing the intake cam shaft to one with a very late valve closing and installing pistons that decrease combustion clearance volume. These changes result in a higher, 12.3:1 compression ratio.

The electric drive motor makes up for the low-end torque losses that are characteristic of five-stroke engines, making the Atkinson cycle ideal for hybridization. The PowerSmart™ system offers both a series path and a parallel path for propulsion and can switch seamlessly between the two.

For example, the vehicle can run on the gasoline engine, the electric traction motor or both depending on the driving situation. The gasoline engine is most efficient at highway speeds, while the electric traction motor provides the most benefit at low-speed city driving.

The internal combustion engine shuts off when the vehicle is at rest, saving fuel. When the driver presses the accelerator, the electric motor restarts the vehicle almost instantly and has the ability to launch the vehicle on its own. When greater acceleration is needed, both the four-cylinder gasoline engine and the electric motor are used in tandem. This provides launch performance equivalent to the traditional Escape's powerful V-6 engine.

Regenerative Braking Recaptures Energy

The regenerative braking system on the Escape HEV is the subject of 51 patent disclosures. When the driver presses the brake pedal, the controller immediately determines the potential for the generator and electric motor to supply braking force through drag and switches them to function as electrical generators. This generator supplied braking force is used to its limit.

The vehicle's mechanical brakes provide the rest of the stopping force as needed. In operation, the friction braking from the vehicle's conventional disc brakes and the regenerative braking through the electric generator occur simultaneously. The gasoline engine also provides compression braking that is captured as energy by the battery.

Both the brake pedal and accelerator are fully electronic controls - known as "drive-by- wire." Pedal feel and overall braking response have been calibrated to closely resemble that of the traditional hydraulic braking system, for driver comfort and confidence.

Among other new technologies featured in the Escape HEV are a new permanent magnet motor. It offers better performance through the speed range and improved efficiency under partial load, in a smaller package.

A new microprocessor was specifically designed for this application, along with new thermal and moisture insulating technologies to improve performance and reliability. Electric power steering assist replaces the usual hydraulic power steering for greater efficiency. The Escape's instrument cluster is modified to include information about the HEV system's operation, including battery condition.

The vehicle's climate control system provides cooling to both the passenger area and the battery compartment. The 300-volt, 45 kW nickel-metal hydride traction battery pack and controller, supplied by SANYO Electric Co. Ltd. of Osaka, Japan, is located in the rear of the vehicle as part of the cargo area load floor. The pack features air cooling, a safety disconnect for service, relays and controllers that will disable the battery in the event of an accident or high voltage leak and tamper-proof safety screws that can only be removed by specially trained technicians.

The Escape HEV will undergo rigorous truck testing to ensure the vehicle is "Built Ford Tough." It will have available 4x4 capability, comparable cargo capacity and the same ground clearance as the base model Escape.

The Escape HEV will qualify as a Super Ultra Low Emission Vehicle (SULEV II) under California standards, meaning that it emits no more than .02 parts per million of smog-forming NOx. It also will meet Stage IV emissions requirements in Europe before they become mandatory in the 2005 model year.
 

Ford Escape HEV featuring PowerSmart transmission jointly devleoped by Ford Motor Company and Aisin A. W.

 Escape HEV engine with PowerSmart Transaxle conected to Duratec HE engine, either 2.0 or 2.3 version.
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NiMh battery pack.