Optimizing fuel efficiency through the drivetrain

“The electrification of the powertrain additionally helps to keep the internal combustion engine operating in its optimum range, which means that hybridization will continue to make rapid advances. Start-stop systems are becoming increasingly widespread and are set to develop from conventional starters into systems that provide features previously only available in hybrid vehicles. Energy recovery will become more and more of an issue as the performance of on-board electric systems and equipment increases. 

After all, a reduction in the vehicle’s fuel consumption and CO2 emissions can also be achieved if this energy is used to drive the vehicle,” he says. Schaeffler has two demonstration vehicles on the road to showcase and test the technology on the road. For the United States market the company has installed its Efficient Future Mobility system in a SUV. “The optimization of powertrains based on internal combustion engines allows even vehicles of this size to achieve the values specified by the CAFE standard for the year 2020,” explains Jeff Hemphill, vice president and chief technical officer of Schaeffler North America. “Our ideas for the electrification of the powertrain also put Schaeffler in a position to give the automotive industry the solutions it needs to fulfill the requirements set out for 2025,” he says. The company also has a concept vehicle on the road in India.

Guzmer: The technology platform is based on the current version of a popular mid-size SUV that is fitted with an automatic transmission and torque converter. The concept vehicle employs Schaeffler systems such as a thermal management module and all-wheel drive (AWD) disconnect clutch. The thermal management module allows the engine to reach its operating temperature quickly and the temperature balance to be precisely controlled. Other solutions that are on board include Schaeffler innovations for engine start-stop systems such as the “permanently engaged starter generator” with a wrap-spring oneway clutch and a latching valve that allows the vehicle to be driven for longer with the engine switched off without the need for energy-consuming pumps. Impressive results have also been achieved through detailed friction optimization work carried out on the belt drive, the valve train and the balancer shafts, as well as the optimization of the torque converter. We have increased the efficiency of the vehicle by up to 15%. 

Guzmer: Schaeffler is documenting the reaction and experiences of customers in various regions of the world with its North America concept vehicle, as well as with the Efficient Future Mobility India concept car. The Indian test is based on a popular economical small car with a manual transmission. One of the products being showcased is an electronic clutch management (ECM) system, which replaces the clutch pedal with an actuator. When combined with gear detection sensors this allows automatic shifting. Other innovations on display in the Indian vehicle include an engine start-stop system, a variable camshaft phasing system, specially coated valve tappets, and an intelligent thermal management system. All of the solutions presented in this vehicle can be implemented cost-effectively, and can improve fuel economy by up to 10% when installed in small cars. Together with Honda we are working on a completely new double clutch transmission with integrated hybrid-electromotor offering a best-in-class fuel consumption in B-Class segment. 

Guzmer: Requirements with regard to CO2 emissions and fuel consumption are increasing all the time. Schaeffler’s innovations support the global automotive industry in meeting them. The product portfolio and product innovations reflect the company´s regional diversification strategy in the fields of optimization of drive trains based on internal combustion engines, electromobility and hybridization. With its close-knit global and flexible network of 17 development centers and 80 production sites, Schaeffler is an innovative and reliable partner for the automotive industry worldwide and able to spread the new Schaeffler strategies and technologies all over the world. 

Guzmer: Schaeffler presented innovations for entry-level 48 Volt hybridization. These solutions were bundled together in Schaeffler’s 48 V System exhibit, which demonstrated how the CAFE standards for 2025 can potentially be met in a cost-effective way. The central element is a compact 48-volt electric drive module that includes a clutch and planetary transmission. It can be placed on either the front or rear axle. This entry-level form of hybridization already offers the essential advantages of a hybrid vehicle, while at the same time, is a low-cost option that allows CO2 emissions to be reduced by up to 15%. 

Guzmer: The system offers potentially enables all-wheel drive (AWD) vehicles to achieve similar fuel consumption to front-wheel drive models without affecting the driving characteristics. The AWD disconnect system comprises of a hydraulically operated synchronizer clutch integrated into the input shaft on the power transfer unit (PTU) and electrically operated dog clutches on the rear axle. It can be integrated into conventional all-wheel drive trains without major modifications. The AWD disconnect clutch decouples the unused drive axle from the drive when AWD is not needed. This results in fuel savings of up to 6% on the highway and around 2% in city traffic. 

Guzmer: The integrated torque converter is a completely revised converter and clutch system in which the clutch function is carried out directly by the torque converter turbine instead of using a separate piston, as was previously the case. This reduces the weight and inertia while making the design envelope smaller, so making it possible to implement innovative damping concepts like the centrifugal pendulum-type absorber (CPA). This technology makes it possible to close the lockup clutch earlier and thus to simultaneously improve fuel economy and comfort. This opens the way for more widespread use of the CPA in the torque converters of automatic transmissions in the future. Over the past 10 years we have more than doubled the maximum torque capacity of our torque converters, while taking up less space. 

There is a further converter innovation that is customized to suit modern, turbocharged engines and represents a revolutionary invention in the field of converters: The multi-functional torque converter, or MFTC, is ideal for use in combination with start–stop systems and can compensate for the delayed response that is commonly experienced. Fuel savings of up to 5% can be achieved with the multi-functional torque converter, the optional idle disconnect function, and early torque converter lockup. The MFTC eliminates converter idling losses because the transmission can be decoupled from the engine.