Skip to main content

Ford mining mileage, new patents from Auto Start-Stop technology

The best technology does its job effectively and then gets out of the way.
Posted: July 5, 2012 - 11:12PM
Author: Don Bain


As they strive to engineer better fuel efficiency for millions of drivers, Ford has more than 25 patents pending from their Auto Start-Stop technology, which is a $295 option on the all-new 2013 Ford Fusion.

“We set out to make Auto Start-Stop in the 2013 Fusion as seamless to drivers as possible,” said Birgit Sorgenfrei, Ford’s Auto Start-Stop program manager. “We wanted the system to improve fuel efficiency but otherwise remain transparent, so we developed a number of unique control strategies to smooth out the performance.”

It was one of the early advantages of the hybrid drive system, which would allow a gas engine to shut down when stopped, such as in rush-hour gridlock. Now this technology is migrating to many straight gasoline vehicles after being developed 15 years ago in the very first hybrid vehicles.

Ford’s Auto Start-Stop will now be available on the new Fusion featuring the 1.6-liter EcoBoost four-cylinder engine.

An ever more common feature on the newest vehicles, Auto Start-Stop switches off the engine when the car stops, instantly restarting it when the driver lets off the brake. This description, however, is a simplification of what really happens and just the tip of an engineering iceberg. That’s why Kirk Pebley and the Ford team have filed over 25 patents for innovations beneath the surface of the electronic controller system.

The new Fusion is the first Ford vehicle to offer Auto Start-Stop with a self-shifting gearbox. Automatic transmission requires maintaining hydraulic pressure even when the engine’s off, so Ford added an electric pump to the transmission, an upgraded starter,as well as an absorbed glass mat battery.

Nevertheless, combining Auto Start-Stop technology with an automatic involved more than just adding a pump. To speed launch after a restart, the engineers wanted the transmission in gear with the engine off – instead of shifting to neutral.

“We had to develop some unique control algorithms for the engine and transmission to overcome this obstacle and still ensure an extremely quick, smooth and quiet restart,” said Sorgenfrei.

“As the vehicle slows down, the brains of Auto Start-Stop are already hard at work even before the Fusion comes to a standstill,” said Pebley. “One of many keys to getting a robust engine restart is to make sure the battery has enough power to spin it back up.”

The controlling software also includes a simulation of the electrical system that constantly monitors the added power loads from accessory systems. It factors in the draw from headlights, climate control, audio and window defoggers; calculating how much power is available while the engine is off and how quickly the battery will drain. If the load is too demanding, Auto Start-Stop may be disabled to prevent a tough restart or a flat battery.

Voltage blending is another aspect currently under evaluation by the United States Patent and Trademark Office.

When the engine is running, the alternator provides from 14 to 15 volts, but the battery only has 12 volts when fully charged. As the Fusion slows down when Auto Start-Stop is enabled, the model tracks vehicle speed and deceleration to decipher when to cut voltage from the alternator, going to battery-only before the car stops. This blending ensures little pleasantries – like the lights not dimming and the ventilation fan not stuttering.

Other patent applications are related to the sophisticated controls for the climate modification system. On hot summer days (is there any other kind these days?), the sun can heat a car interior in mere minutes, quickly making driver and passengers thoroughly uncomfortable. In addition to interior temperature and humidity, Auto Start-Stop monitors the evaporator core noting any rise even before occupants feel any change. In this instance, the engine will restart sooner, keeping heads and travel for all cooler.

In any type of car driver behavior is important to its ultimate efficiency. A more knowledgeable driver makes better decisions, saving dollars at the pump. An innovative SmartGauge instrument cluster has given Fusion drivers such valuable feedback since the current-generation Fusion Hybrid debuted in 2009.

“When Auto Start-Stop is disabled because of a high accessory load, we wanted drivers to understand why so that they could opt to switch some things off if it’s appropriate,” said Pebley. “If the rear defrost is still on but the window is clear, they can switch it off to gain the efficiency benefit of shutting down the engine when the car stops.”

The 2013 Fusion with Auto Start-Stop is unique in providing this sort of coaching in non-hybrid vehicle.

“Smart decisions are born from having more complete information,” said Sorgenfrei. “Whether it’s the messages we provide to drivers or the dozens of signals that help the control system look ahead in time, the 2013 Fusion Auto Start-Stop helps drivers save on gas without getting in the way.”

The bottom line is simply that even though drivers might not feel it working, the fuel savings of up to 10 percent can save up to $1,100 compared to other midsize sedans over five years of ownership. Finding a car that pays you back to drive it, is a significant part of the equation today.