Ford Blends Math, Creative Thinking, Computing Power to Bring Superior Shift Quality to Focus
* 2012 Ford Focus, featuring a 2.0-liter direct-injection gasoline engine and PowerShift dry-clutch six-speed automatic transmission, incorporates Ford’s patented Torque Hole Filling (THF) technology for smoother, more seamless shift quality
* THF uses a combination of mathematical modeling and computer-aided engineering tools, along with other enabling transmission technologies to deliver smoother upshifts
* Originally penned in 1986, the Ford-developed THF invention disclosure came to fruition as computing power and transmission technologies caught up with the pioneering idea
* In internal evaluations, THF improved shift quality ratings by up to 2 points (out of 10) in comparison to baseline shifts with conventional controls
DEARBORN, Mich., – The 2012 Ford Focus will offer up exceptional shift quality to drivers, powered in part by an inventive Ford transmission technology that has been waiting nearly 25 years for computing power to catch up to make it a reality.
Focus features the Ford PowerShift dry-clutch six-speed automatic transmission, one of the first transmissions to benefit from Torque Hole Filling (THF), a Ford-developed and patented concept and methodology conceived a quarter century ago. THF uses a combination of mathematical algorithms, computer-aided engineering (CAE) tools and transmission control technologies to fill what is commonly known as the torque hole – the slight hesitation drivers may feel during an upshift when there is a momentary drop in transmission torque output followed by a rise in torque.
The torque hole has been inherent to automatic transmissions since the 1940s, said Ford Research Technical Expert Chris Teslak. “Even though much work in controls and calibration has been done over the years, it has remained a major challenge,” he said.
To address this challenge, Dr. Davor Hrovat, a Ford Technical Fellow in Controls Research, authored an invention disclosure in the mid-1980s on how to coordinate engine and transmission controls to help eliminate the torque hole. Further analytical work and simulation revealed this pioneering concept was promising, but the technology needed to implement it wasn’t fully mature yet.
“Although the team has known what was needed to create smoother shifts, the actual implementation had to wait for drive-by-wire technologies, electronic throttle control and processing power to catch up to transform this inventive idea into a reality,” said Teslak, who credits THF project technical leaders Yuji Fujii and Eric Tseng, along with other core technical experts/engineers Jahan Asgari, Tom Brown, Chad Griffin, Don Levens and Brad Riedle for helping to bring THF to fruition under Hrovat’s guidance.
Enabling technologies such as electronic throttle control and improved actuators and sensors, coupled with the THF methodology, gave the team of Ford engineers the tools needed to precisely sync transmission and engine to transfer and smooth out the torque during a portion of an upshift lasting a fraction of a second. Adding that little extra torque during the shift helps fill the hole, creating a smoother drive experience for the customer.
In internal engineering evaluations using a PowerShift prototype, THF improved shift quality ratings by up to 2 points on a scale of 1 to 10 in comparison to baseline shifts with conventional controls.
“THF uses dynamic modeling and proprietary algorithms to command the additional engine torque that’s essential for maintaining driver-desired (communicated via the gas pedal) wheel torque in a precise, coordinated way with the clutch control,” said Riedle, Ford technical expert in transmission electronics.
To pre-stage this fraction-of-a-second “conversation” between engine and transmission, a certain degree of finesse, coordination and upfront knowledge of what customers perceive as a quality shift was needed. The technology also required the Ford engineering teams from several disciplines to throw away preconceived notions about conventional engine and shift controls.
In total, the team logged approximately three years or 6,000 man-hours of computer-aided mathematical modeling, simulation and analysis of engine speeds, torque and clutch capacity in only 24 months real time to prove the THF concept was production-ready.
“This methodology is the result of persistence, teamwork, creative thinking and a desire to move beyond existing shift dynamics,” said Teslak. “THF enables a consistently smooth shift feel with minimum calibration effort and no incremental hardware cost.
“More importantly, it’s a portable technology that can be applied across multiple powertrain/transmission powerpacks, giving us the ability to quickly deliver best-in-class shift quality across platforms.”
Ford has two U.S. patents covering broad THF applications and several other related patents are pending. Further research on how to most effectively incorporate THF into more conventional planetary gear-based transmissions is ongoing.
About Ford Motor Company
Ford Motor Company, a global automotive industry leader based in Dearborn, Mich., manufactures or distributes automobiles across six continents. With about 163,000 employees and about 70 plants worldwide, the company’s automotive brands include Ford and Lincoln. The company provides financial services through Ford Motor Credit Company. For more information regarding Ford’s products, please visit www.ford.com.
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