Press Release
Powertrain
Thanks to its advanced powertrain, the Mercury Mariner Hybrid provides environmental stewardship without sacrifice. It offers the versatility of a sport-utility, including impressive acceleration, cargo and companion capacity, and the ability to tow 1,000 pounds. Yet, Mariner Hybrid also delivers remarkably low emissions that are expected to qualify for Advanced Technology Partial Zero Emissions Vehicle (AT-PZEV) certification in California, and other states that have adopted California's clean-air standards. Mariner is also remarkably frugal with gasoline, with an estimated fuel economy of 33 mpg in the city, 29 mpg highway.This remarkable feat is accomplished by six powertrain components that work in perfect unison. Ford Motor Company has received more than 40 patents, and has another 70 patents pending, on these powertrain technologies shared with the Ford Escape Hybrid. The integration of these technologies into a customer-friendly, advanced powertrain helped the Escape Hybrid recently receive the 2005 North American Truck of the Year Award.
Gasoline Engine: Duratec 23 is lightweight, fuel efficient
Mariner Hybrid features a lightweight version of Ford's Duratec 23 2.3-liter four-cylinder engine. The block and head are aluminum, which saves 40 pounds compared with the conventional Duratec 23. A second mass-saving feature is a friction-welded plastic intake manifold. Finally, the piston, ring and connecting rod assembly is 15 percent lighter than comparable modern engines. Less weight aids both fuel efficiency and acceleration.Mariner Hybrid's gasoline powerplant is a double-overhead-cam design with four valves per cylinder, pent-roof combustion chambers, and centrally located spark plugs for optimum breathing and efficient combustion. Direct-acting mechanical bucket tappets require no lash adjustment during a 10-year, 150,000-mile service life. Four-orifice fuel injectors provide a better spray pattern and finer atomization than is possible with more common single-orifice injectors. Butterfly valves positioned in the intake runners restrict airflow at low speeds to induce tumble as the fuel-to-air mixture enters the combustion chamber. Counter-rotating balance weights help eliminate vibration.
Unlike most modern engines, Mariner Hybrid's engine uses a special Atkinson combustion cycle for improved efficiency. This consists of a 12.3:1 expansion ratio to extract more energy from every drop of gasoline and late-closing intake valves to minimize pumping losses. Keeping the intake valve open longer yields a compression ratio below 9.0:1 at low speeds for good drivability (no detonation) and a much higher compression ratio at high rpm for increased peak power.
Tuned for hybrid applications, the Duratec 23 generates 133 horsepower at 6000 rpm and 129 foot-pounds of torque at 4500 rpm.
The engine switches off at low speeds and light loads to conserve fuel, while propulsion is handled solely by the traction motor (below). The engine can also shut down during coasting and while the vehicle pauses at a stoplight to further reduce unnecessary fuel consumption.
Electric Traction Motor: Assisting the gasoline engine
The small and efficient four-cylinder engine is augmented by an electric motor during periods of high demand ??????????????????????????????????????? for accelerating smartly to freeway speeds, transporting five occupants and their gear, or towing a 1,000-pound trailer. This arrangement contributes to reduced fuel consumption and increased performance. Combined, the gas and electric hybrid partners provide an effective 155 peak horsepower from 35 mph to the speed limit, yielding performance that feels similar to a V-6-powered Mariner, especially during passing maneuvers.Mariner Hybrid's traction motor is a compact permanent magnet design that operates on AC power drawn both from the generator and battery pack (via a power inverter that converts stored DC to AC). Its peak power is 70 kilowatts (equivalent to an extra 94 horsepower) at 3000 to 4000 rpm. Since electric motors deliver maximum torque at low rpm, they are an ideal complement to gasoline engines, which generate peak torque at higher rpm.
During braking, the traction motor temporarily becomes a generator. That generates negative torque to slow the vehicle, lessening the burden placed on Mariner's four disc brakes, and helping recharge the electric battery pack. Engineers call this conversion of momentum into electricity regenerative braking, and it represents a major part of Mariner Hybrid's efficiency advantage over conventional vehicles.
Planetary CVT: Efficient power delivery
A conventional automatic transaxle serves as the intermediary between the engine and the drive wheels. Mariner Hybrid's advanced, electronically controlled transaxle handles that task plus several others. Inside this ingenious device, you'll find one planetary gear set versus the two or more usually found in a conventional automatic. But instead of shifting from one ratio (gear) to the next in steps, the transaxle engineered specifically for use in hybrids does its work seamlessly, with no jerks, jolts, power interruptions or detectable ratio changes. Engineers call this a continuously variable transmission or CVT. Note that this transmission differs from the more familiar CVTs that use a variable pulley and steel belt.Mariner Hybrid's transaxle is a key component of the full hybrid system, as it smoothly blends together contributions from the engine and traction motor. As a result, the gasoline engine can be shut down at low speeds and light loads to save fuel, while propulsion is handled solely by the traction motor. The transaxle also routes a portion of the power produced by the engine to a generator.
Generator: Keeps the current flowing, the engine starting
On the Mariner Hybrid powertrain, the generator handles three important tasks. Its primary responsibility is generating electric current. Most of that energy is used to charge the battery pack during cruising but some of it is routed directly to the traction motor during heavy-load situations such as climbing steep hills or accelerating briskly to cruising speed. The second task is restarting the gasoline engine after shutdown for stoplights and coasting. In this instance, the generator acts as an AC motor. Rated at 28 kilowatts or 38 horsepower, it has no difficulty refiring the engine more rapidly than a conventional starter. The generator's third responsibility is controlling the drive ratio in the transaxle's planetary gear set so that the gasoline engine runs at its most efficient load and rpm as often as possible.
Battery Pack: Electric fuel tank
Mariner Hybrid's battery pack stores electrical energy for starting the gasoline engine and for supplementing its power output (via the traction motor). The pack consists of 250 nickel-metal hydride D-size cells connected in series, packaged under the cargo floor.Thermal controls ??????????????????????????????????????? an electric heater and fan-driven cooling air ??????????????????????????????????????? maintain operating temperatures so this pack can operate in ambient temperatures ranging from -40 to 120 degrees Fahrenheit. "Batteries are like people," says Watson. "They don't like to work when they're cold, and get hot when they're stressed."
The temperature control duct is integrated into the driver's side of the cargo area, discreetly vented by the rear window.
Total battery capacity is 5.5 AmpHours and operating voltage varies between 216 and 397 volts. In the discharge mode, the battery pack can deliver up to 39 kilowatts of power and its maximum recharge rate is 31 kilowatts.
While it's never necessary to plug Mariner Hybrid into a charger, in the unlikely event that insufficient energy is available to start the gasoline engine, jump starts are possible. A conventional 12-volt lead-acid battery is also provided to power Mariner's accessories such as the keyless entry system.
Nickel-metal hydride batteries have been used with excellent success in notebook computers and cell phones for years. Mariner Hybrid's battery pack is covered by warranty for eight years or 100,000 miles. To meet AT-PZEV requirements in states that follow California's emissions standards, the warranty is extended to 10 years or 150,000 miles. Since the 12-volt battery has absolutely no engine cranking responsibilities, it, too, should provide a longer than normal service life.
Electronic Controller: Directs and integrates the powertrain systems
A suite of microprocessor-based control modules manage and integrate Mariner Hybrid's powertrain-related functions. The master device is a vehicle systems controller built into Mariner's powertrain control module. The engine controller is also housed within this under-hood device. The transmission control module, traction battery control module, brake system control module, and Intelligent 4WD controller are located near their respective components and wired so they can maintain two-way digital conversations with the vehicle systems controller by means of a high-speed data network.On-board electronic devices convert the AC current produced by the generator motor and the traction motor to DC voltage suitable for recharging the battery pack. Likewise, power from the batteries must be inverted to AC to power the traction motor. In addition there are circuits that start and stop the gasoline engine and others that switch the traction motor to a generator during braking. Safety measures are also included to isolate high-voltage circuits in the event of tampering or a collision. When the vehicle is switched off, connection to the battery pack is interrupted.
Intelligent 4WD System: Off-road and all-weather traction
Fully automatic, electronically controlled, Intelligent 4WD is standard Mariner Hybrid equipment. In normal dry-pavement driving, propulsion is provided solely by the front wheels. A control computer monitors wheel speeds and accelerator position dozens of times per second to avoid slip and to optimize traction. If slippage is detected, an electromagnetic clutch controlled by the computer apportions the ideal amount of torque to the rear wheels until traction is regained.Reaction times are faster than hydraulic or viscous-based systems and Intelligent 4WD engagement is so smooth and automatic that most drivers never sense its operation. There's no binding during tight turns and excellent traction on slippery surfaces.
