SOUTHFIELD, Mich. — Federal-Mogul has developed a new seal design called MicroTorq, which the company says reduces friction by up to 70 percent versus conventional lip-type seals. The new seal can provide an improvement in vehicle fuel economy of up to 0.49 percent and a reduction in CO2 emissions of 1-2 g/km compared to traditional seal designs, according to Federal-Mogul.
The company says the new seals also are easier to install, more accommodating of shaft misalignment or eccentricity and require less package space. Benefits of the product can be achieved relatively simply, even on existing engines as the new MicroTorq seal can be utilized without changing the design of adjacent components.
The friction contribution from a pair of conventional crankshaft oil seals can account for up to 3.5 g/km of a vehicle’s CO2 output, depending on the sealing technology, even at modest engine speeds of around 2000 rpm. "By adopting a fundamentally new design approach, we have developed a family of low friction seals that offer vehicle manufacturers a simple, cost-effective and easily implemented route to reduced emissions and improved fuel economy," said Larry Brouwer, director, sealing technology and innovation, Federal-Mogul Powertrain Sealing and Bearings. "There are very few technologies that offer such an affordable route to CO2 reduction, making this an extremely attractive solution for all vehicle manufacturers."
Friction occurs because conventional lip seals are preloaded against the crankshaft to maintain sealing when the crankshaft moves within the bearing clearance under varying load conditions. As well as consuming energy, friction at the seal’s lip creates heat that degrades the oil, causing a build-up of carbon that destroys the hydrodynamic function of the seal lip, leading to oil leakage.
Federal-Mogul says the MicroTorq seal overcomes these problems by virtue of its innovative “dual-hinge” lip design that allows the main sealing element to maintain uniform contact with the shaft under conditions of varying geometry while maintaining a light contact load at both the main lip and the dirt excluder lip. Unique hydrodynamic features molded into the seal are shaped to efficiently pump oil back into the engine while the crankshaft is turning, and provide static sealing when it is not. The MicroTorq seal is also equipped with a piloting foot that allows error-free installation every time, without the use of special tools, simultaneously simplifying the assembly process and improving installation robustness. Additionally, while conventional seals require 7-10 mm of axial space on the crankshaft, the MicroTorq seal can be packaged in under 5 mm, contributing to the design of compact lightweight engines.
The company says it has carried out extensive validation and durability testing on the new seal technology, confirming the advantages of the new approach. Dynamic tests at various speeds showed MicroTorq to generate approximately one-third to half the friction torque of conventional seal designs on average, while pressure/vacuum testing and air sealability tests demonstrated substantial benefits for the MicroTorq design. When conventional crankshaft seals were replaced with MicroTorq seals, calculated fuel consumption yielded improvements between 0.25 percent for a compact car equipped with a two-liter engine and a 6-speed automatic transmission and 0.49 percent for a V8 pickup truck.
"MicroTorq seals can offer an immediate CO2 savings of 1-2 g/km on current engine applications and up to 3.5 g/km for new engine development with almost no additional cost," said Gerard Chochoy, senior vice president, Federal-Mogul Powertrain Sealing and Bearings. "That’s a big opportunity for Federal-Mogul customers using combustion engines in their vehicles or power generation applications." Federal-Mogul expects to announce the first high-volume production application of the new seals later this year.
