A new torque converter that is smaller and lighter in weight than its predecessor adds crucial functionality for vehicles powered by downsized engines paired with an automatic transmission.
“The downsizing trend means we’re seeing three-cylinder engines firing on two cylinders, which is an extraordinarily violent forcing-function for vibration," observed Jeff Hemphill, Chief Technology Officer for Schaeffler North America. At his company's recent technology symposium in Detroit, Hemphill and colleagues detailed the LuK iTC (integrated torque converter), a simplified design that incorporates a damper "to handle those vibrations and allow fuel to be saved by the downsized engine,” he said.
The new iTC eliminates the 3-mm to 4-mm (0.11-in to 0.15 -in)-thick piston plate used in Schaeffler's previous torque converter, noted Markus Steinberger, Section Leader of Advanced Torque Converter Design for LuK USA. As a result, the turbine is now thicker because engineers had to integrate the function of the piston with the turbine. Schaeffler combined "two components that we’ve had inside the torque converter for several decades, into one component,” Steinberger explained in an Automotive Engineering interview.
Reduced mass is another benefit. The iTC weighs 10.7 kg (23.5 lb), a 2.4 kg (5.20 lb) savings versus the predecessor’s 13.1 kg (28.8 lb). “And by taking a component out that was 3 to 4 mm thick plus the clearance around it, we’re saving about 5 to 6 mm (0.19 to 0.23 in) in axial space on the torque converter,” Steinberger said.
LuK’s multi-function iTC can be fitted with an impeller clutch, enabling the engine to operate at a higher speed than the impeller. Because the impeller is not connected directly to the engine, the engine can provide a higher torque faster. On a turbocharged engine configuration that helps reduce the effects of turbo lag.
The iTC designs allows for an impeller clutch without a major design change because the impeller clutch can be integrated into the iTC’s turbine clutch. In addition to two standard pressure channels, there is a third channel running from the back of the impeller clutch into the oil sump, Steinberger explained.
With 2025 U.S. fuel-economy mandates in play, improved fuel economy is an industry priority.
“We’re really hitting fuel efficiency from different sides," Steinberger said. "The iTC’s weight savings translates to fuel economy improvements. And because we can fit a bigger damper inside the torque converter that allows the powertrain to run more efficiently.”
The first production application of the iTC is possible as early as the 2017 model year. “We’re now working on front-wheel drive and rear-wheel drive application prototypes with American and Asian automakers,” he revealed.