When it comes to sustainable mobility – including electric vehicles and gasoline/electric hybrid systems, Nissan is known for its innovative approach. More than 50,000 Nissan LEAF EVs have been sold around the world in just its first two years, affirming Nissan's position as the global leader in affordable production electric vehicles and advanced Lithium-ion (Li-ion) battery technology. The company's "one-motor, two-clutch" gasoline/electric powertrain parallel hybrid system made its production debut in the United States in spring 2011 in the rear-wheel drive Infiniti M Hybrid – a vehicle delivering more than 350 horsepower and 30 miles per gallon fuel efficiency.
Now Nissan has adapted its advanced Intelligent Dual Clutch System to create a new front-wheel/four-wheel drive hybrid system that will debut in the U.S. in late summer 2013 in the fourth-generation Nissan Pathfinder SUV (for full details on the 2014 Pathfinder Hybrid, please go to NissanNews.com).
While the high performance hybrid system utilized in the premium Infiniti M Hybrid is highly appropriate to a luxury sports sedan, the new Pathfinder's hybrid system is designed to provide milder performance and fuel economy gains at a more affordable price for a wider customer base. Said Nissan North America, Inc. Vice President, Product Planning Pierre Loing: "The new system used in the 2014 Pathfinder Hybrid serves as the natural evolution from conventional internal combustion powertrains to the wider adaption of hybrid systems. With its compact packaging and light weight design, it is ideal for use in family vehicles such as the Pathfinder where interior passenger and cargo space are critical – and where the system's design preserves the same abundant amount of space offered by the conventional Pathfinder."
Three key elements are critical to the design of the new hybrid system, all of which are already available in the Nissan technology catalog:
A range of downsized internal combustion engines, such as the new Pathfinder Hybrid's 2.5-liter inline 4-cylinder – which has been fitted with a Roots-type supercharger to give it horsepower (250 hp) and torque (243 lb-ft) similar to the non-hybrid Pathfinder's standard 3.5-liter V6.
An advanced Xtronic CVT® (Continuously Variable Transmission) that maximizes engine operating efficiency with both the gasoline engine and electric motor compared to a fixed gear ratio transmission. Nissan's industry leadership in CVT design includes the latest generation Xtronic CVT®, used in all Pathfinder models, that features greatly reduced internal friction, a wider ratio coverage than most automatic transmissions, and compact size – allowing the Pathfinder's CVT and integrated motor-clutch configuration fit in the same space as the conventional vehicle's transmission.
And finally, a compact Li-ion battery system that is both powerful and easily configurable for a variety of applications so as not to intrude into the passenger or cargo areas. For use in the new Pathfinder Hybrid, the battery fits compactly under the 3rd row passenger seat, so there is no difference in passenger or cargo volume versus the conventional Pathfinder models.
"This new system is not only adaptable to front-wheel drive and four-wheel drive configurations like with the new Pathfinder, it is completely scalable depending on vehicle design or segment," said Loing. "For example, with Pathfinder it is used with the supercharged 2.5-liter engine, 15 kW electric motor and relatively small battery pack – retaining solid SUV capabilities including standard towing capacity of 3,500 pounds. For use in an urban compact or sedan, the system might include a smaller 2.0-liter engine but a more powerful electric motor and larger battery to extend the pure electric driving range for city stop-and-go traffic use. There is complete design flexibility with this system – along with an affordability factor because it uses readily available components."
The New Nissan FF-Hybrid System in Detail
Compact and adaptable to vehicles of any size, the new FF-Hybrid powertrain achieves smooth and direct acceleration, excellent fuel economy and it significantly narrows the price premium over conventional internal combustion engines.
As with the FR-Hybrid, the FF-Hybrid utilizes the unique one-motor, two-clutch configuration known as the Nissan Intelligent Dual Clutch System. The electric motor is linked with a Lithium-ion battery. Positioned between the gasoline engine and the Xtronic CVT® (where the torque converter would normally be), the motor also functions as a generator, conveying deceleration force from the CVT to the battery. As for the two clutches, one is installed between the gasoline engine and the electric motor, the other between the motor and the CVT.
When both clutches are engaged, the engine and electric motor connect directly to the CVT, allowing the electric motor to augment torque from the engine as required. This creates the potential for powerful acceleration.
The high input/output Li-ion battery is automatically topped up by regenerative power from the brakes by converting the vehicle's kinetic energy otherwise lost in braking.
FF-Hybrid system for 2.5L, supercharger
Pairing this battery with a smaller engine than conventional gasoline vehicles, closely integrated with an electric motor and CVT, results in a highly compact and cost-effective package that can be adapted for use in a range of applications.