АКПП Ford 6F35 (GM 6T45)

All Six-Speed Transmission Lineup Improves Fuel Efficiency and Fun-to-Drive Factor of Ford Fusion

Oct-30-2008 12:00 AM ET
DEARBORN The addition of the 6F35 six-speed transmission to the 2010 Ford Fusion s powertrain lineup is a competitive advantage that helps deliver double-digit fuel efficiencies, increased horsepower and a more robust drive experience for customers.

All three of the 2010 Fusion s engine offerings the 2.5-liter I-4, the 3.0-liter V-6 and the 3.5-liter V-6 are mated to six-speed transmissions. The six-speed marriage is a first for Fusion I-4 models, replacing an outgoing five-speed gearbox, which remains the gearbox similar to those still offered by segment volume leaders Toyota and Honda.

The increased gear span offered by the advanced six-speed transmission allows the Fusion s powertrains to operate at more optimum levels. A higher first gear, for example, delivers more torque when accelerating from a stop while the deeper overdrive gear enables a vehicle s engine to use less energy at highway cruising speeds, saving fuel. As a result, Fusion customers will gain a 10 percent improvement in fuel efficiency on the 2.5-liter and at least 6 percent improvement on the V-6 powertrains, while enjoying enhanced acceleration and drive feel.

The 6F35 is a highly intelligent gearbox that provides all the customer wants, including increased power, smoother shift feel, a quieter ride, and good fuel economy in one package, said Adam Vahratian, transmission systems manager for Ford Powertrain Operations.

The 6F35 is designed to provide customers superior shift quality, improved fuel efficiency as well as best-in-class levels of noise and vibration.

The smooth ride is due in part to direct electronic shift control and short steps in between intermediate gears that find the right gear fast for optimal operating conditions. The 6F35 also has six available final drive gear ratios and utilizes adaptive learning algorithms, to make the transmission customizable to individual vehicles for better performance as well as fuel economy.

Shift quality of the 6F35 is further improved thanks to integrated engine and transmission controls in one powertrain control module (PCM). This smart PCM has custom trimmed solenoids and custom characterized clutches to give Fusion superior performance characteristics.

Running both engine and transmission in one microprocessor is not only more cost-efficient, but it helps us beat the pants off of our competitors in terms of shift quality, said Craig Renneker, chief engineer with Ford s automatic and manual transmission programs. Making it happen was no easy feat, requiring a highly complex cooperative effort between engine, transmission, product development and manufacturing.

While the six available gear ratios contribute to smooth shifting, they also play to better fuel economy as does a tall overdrive, more fuel-efficient pumps and a continuous slip torque converter clutch.

In terms of quiet quality, the 6F35 has hard finished gears for more precise fits and reduced whine, an improved die cast aluminum housing that reduces noise radiation and optimized pump porting to reduce pressure ripple and noise.

Joining Fusion s powertrains and the 6F35 gearbox required the Ford transmission team to make some specific modifications for optimal performance. Fusion, for example, uses a different set of final drive ratios than the 2009 Ford Escape/6F35 pairing to deliver better performance and fuel economy on the sedan s 2.5-liter and 3.0-liter engine applications.

Fusion also has an improved converter lock-up for improved efficiency, a recalibrated continuous slip torque converter clutch to accommodate a fuel-saving aggressive deceleration fuel shut-off system as well as other tweaks to diminish parasitic losses.

The Ford transmission team also revamped the 6F35 to accommodate a SelectShift function on Fusion s 3.0-liter engine configurations. SelectShift gives customers the option of a fun-to-shift manual experience. It has a second-gear start with a plus/minus control for each gear.

In SelectShift mode, the transmission doesn t second-guess the driver, giving him or her total control over gear selection and performance feel. Upshifts, for instance, are not commanded at redline and downshifts are allowed at the lowest gear possible as defined by the engine speed.

When the system is in manual mode, engine speed matching provides faster and smoother downshifts and the customer gets the gear they request within the limits of the rev limiter, said Vahratian.

To illustrate: When a lower gear is selected while descending a long downhill grade, the Fusion in SelectShift mode will hold that gear until the driver manually up-shifts or returns to the fully automatic setting. To ensure safe shifting, the transmission will downshift to the lowest acceptable gear, based on a calculated maximum speed. That means if a vehicle was travelling at highway speeds, the driver could not downshift to first gear in SelectShift mode.

Fusion I-4 andV-6 models also feature a grade-assist or hill mode to improve the drivability of the transmission in hilly terrain. This technical innovation uses vehicle input acceleration, pedal position, vehicle speed and brake status to automatically determine the correct gear ratio while on an incline or decline.

Hill mode eliminates sixth gear, extends lower gear operation on uphill climbs, and provides additional grade or engine braking for coast downs. In hill mode, the transmission can determine if a vehicle is accelerating and will downshift to maintain vehicle speed, said Vahratian.

The 6F35 is the company s newest six-speed, debuting earlier this year on the 2009 Ford Escape and Mercury Mariner, an addition that helped the compact SUVs capture best-in-class fuel economy leadership in their segment, beating out the Toyota RAV4 and the Honda CR-V.

By the end of 2012, nearly 100 percent of Ford s North American transmissions will be advanced six-speed gearboxes, building on Ford s sustainability strategy to improve fuel economy and reduce greenhouse gas emissions by 30 percent in new vehicles by 2020.