Timken: Bearings Boost Fuel Economy

Against the looming possibility of federal legislators hiking auto-industry corporate average fuel economy standards by nearly 50%, one longtime supplier is holding out the promise of a large and immediate efficiency boost — for a comparatively minor investment.

Executives and engineers at the Timken Corp. say at a recent presentation at the company's technical center in Canton, OH, that it can make any existing automotive engine as much as 5% more efficient simply by installing the company's signature roller bearings to reduce friction for all key internal engine components that use conventional bearings.

What's the price tag for getting one-tenth of the way from today's 24-mpg (9.8 L/100 km) passenger-car CAFE standard to the 35-mpg (6.7 L/100 km) target set for 2020? Timken says a $50 to $80 premium over the cost of an engine using standard bearings.

Timken says it's time to approach bearings as another engine component that can, and should, be improved.

“It's definitely looking at the powertrain as a system,” says Al Deane, Timken's senior vice president-technology.

Although there has never been a mainstream automotive application, Deane says its “rollerized” engine concept is anything but unproven.

He and other Timken engineers note that roller bearings have for many years been used instead of conventional sleeve bearings for various engine components in the motorcycle and marine industries — a practice begun because those engines have, until recently, typically been 2-strokes, with unique friction characteristics and environmental factors that sometimes demanded the low-friction, low-lubrication qualities of roller bearings.

Deane says installing roller bearings in series-production automotive engines has not been tried largely because there has been no overwhelming excuse for the added cost. With the auto industry facing potential upheaval in its current fuel-efficiency paradigm, that no longer is the case.

Timken's rollerized engine concept places low-friction, split-pin roller bearings at all crankpin, main bearing, crankshaft journal positions and roller bearings at all cam-follower positions.

The result is a 25%-30% reduction in overall friction as measured at the crankshaft — and added fuel efficiency that amounts to about one gallon (3.8 L) of gasoline saved weekly for the average American driver whose vehicle has a V-6.

At $3 per gallon, Timken's rollerized engine would pay for itself in six months. In the context of the thousands of dollars in extra cost for the increased efficiency derived from hybrid-electric systems or diesel engines, investment in a rollerized engine appears to be a fuel-economy bargain.

“We've been using the same (bearing) technology for roughly the last 100 years,” says Stephen Johnson, director-friction management technology. “Why wouldn't you take (roller) bearing technology and apply it?” Johnson says the rollerized engine concept provides other meaningful benefits.

Because of the reduced friction, lubrication requirements are markedly less than for engines using conventional sleeve bearings.

That means a potential downsizing of the entire lubrication system — not to mention less oil needed in the crankcase. Johnson says a conventional engine that requires four quarts of oil would need just three when rollerized. Multiply that 25% reduction in lubrication oil by the millions of oil changes in the U.S. each year and the savings are obvious, he says.

The lower-friction rollerized engine also is much easier to start, say Timken engineers, offering potential for downsizing the starter and battery. And a rollerized engine would be ideal in a “mild” hybrid-electric vehicle application, they say, in which the engine is shut down every time the vehicle comes to rest.

Finally, Timken says an engine with reduced friction is able to produce more power. This is an aspect that had been exploited in motor sports, where Timken has close associations in NASCAR. But Deane says the rollerized engine was subsequently banned for having an unfair advantage.

There are hurdles to clear before rollerized-engine technology can be implemented in mass production.

First, roller bearings require more space, which can create packaging challenges in V-6s, which are popular in the U.S.

Deane also says an engine converted completely to rollerized bearings is noisier, but that the problem is being addressed.

Timken engineers hint a production contract for the rollerized engine may be coming, but they refuse to say if a definitive deal has yet been inked.