With carmakers zooming forward to meet stringent government goals of 54.5 miles per gallon per corporate average fuel, the lowly engine seal is playing a major role, thanks to products designed and manufactured by Freudenberg NOK and sold under the Levitex brand name.
The Levitex crankshaft seal is revolutionary, according to Matthew Portu, president of Freudenberg-NOK Sealing Technologies, because the gas-lubricated face seal functions with a cushion of air reducing both fuel consumption and CO2 emissions by as much as 1 gram per kilometer driven. A 1 gram reduction in CO2 emissions is the equivalent of approximately 0.2 mpg savings in gas for a vehicle rated at 33 mpg.
The Levitex crankshaft seal significantly reduces friction losses in the conventional drive system. Car buffs know that internal combustion engines are frustratingly inefficient. Less than a third of energy from fuel actually moves the car forward. Friction, which occurs when two surfaces contact, retards the fuel efficiency even more. If it happens with ease, the operation is smooth but inefficient. If the car is running low on oil, the parts heat up and wear faster. Friction uses fuel, increases wear and operating temperatures – a lose, lose, lose engineering problem.
A Levitex seal consists of two rings, one of which is firmly attached to the crankshaft and the other to the housing. One of the rings has specially designed grooves that are just a few micrometers deep. As the crankshaft rotates, the air is dragged against the sealing dam that encloses the grooves. The grooves taper to the closed tip, thereby producing a cushion of air that separates one sealing surface from the other. The sealing elements are the steel rings. The proprietary elastomeric compound provides the spring force that keeps the rings pressed together. This is versus standard seals where the elastomer is the actual sealing element.
“The stable air gap creates a nearly frictionless seal for the engine,” said Portu, speaking at the Society of Automotive Engineers in Detroit earlier this month. Freudenberg transposed gas-lubricated seals currently used in industrial facilities that could withstand temperatures from -40 to 150 degrees C or -40 to 302-degrees F.
The manufacturer – already dominant in the automotive sealing business – claims the elastomeric compound seals are so tight that they are impervious to dust and water. These seals can be installed easily on today’s smaller, more powerful engines and powertrains.
“In view of the ambitious C02 goals that become effective in 2020, the focus will be on saving every gram,” said Dr. Eberhard Bock, the head of strategic product development at Freudenberg Sealing Technologies.
The gas-lubricated crankshaft seals are not the only technology that Freudenberg-NOK is using to help automakers reduce the CO2 emissions of upcoming vehicles. The company also introduced a family of low friction simmering seals based on ACM 380, a rubber compound that reduces friction up to 20%. It also offers a cassette seal especially for commercial vehicles that reduces crankshaft friction by 60% while sealing out dirt.
These innovations are part of Freudenberg’s Low-Emission Sealing Solutions or LESS initiative that includes lightweight design innovations for the future of gas sipping vehicles.
