Small-Displacement Engines Integrating Cylinder Shutdown

Cylinder deactivation, a fuel-saving technology that has made V-8-powered pickups and SUVs more palatable for economy-minded buyers, is on the brink of resurgence.

With a corporate average fuel economy mandate of 35.5 mpg (6.6 L/100 km) taking effect in 2016, the two primary suppliers of electronically controlled cylinder-deactivation (CD) systems each tell Ward’s they have about 20 programs in the works with OEM customers.

Together, Eaton Corp. and the Schaeffler Group’s INA division say they expect about 12 of those to reach production within the next three years. New V-8s are scarce among the likely prospects.

“Everybody’s interested in cylinder deactivation,” Bob Zito, director-engineering for engine components at Schaeffler Group USA Inc., says of OEM customers.

“There’s more money going into the powertrain for fuel economy these days than there was 10 years ago,” says David Genise, director of engineering-valvetrain at Eaton’s Vehicle Group, which manufactures 300 million engine valves annually.

Moving the technology forward is the trend toward downsized engines. Since 2004, CD has been heavily employed in OHV V-8 engines from General Motors Co. and Chrysler Group LLC for fullsize pickups, SUVs and cars.

GM says it has more than 2.7 million vehicles on the road globally with CD. In North America, Chrysler has produced 827,000 million CD V-8s for vehicles sold in the U.S. since 2004, according to Ward’s data.

Honda Motor Co. Ltd. also has the technology on a 3.5L SOHC V-6 and on 4-cyl. engines in hybrid applications.

Rocker arm enables Eaton’s cylinder-deactivation system.

The wave of new programs from Eaton and Schaeffler are focused on overhead-cam engines, mostly of the 4-cyl. variety.

For years, multi-valve dual overhead-cam engines were considered poor candidates for CD because they were twice as expensive – requiring twice the hardware – when compared with OHV engines.

That’s one reason Ford Motor Co., which has few OHV engines, has no CD programs in production, nor any planned, a Ford spokesman says.

But smaller engines make the cost differential less onerous, and new technologies are quelling some of the vibration issues associated with small-displacement engines, even those with just two cylinders.

Plus, the CD penetration rate is spurred along by mandates in the U.S. and elsewhere requiring higher fuel economy.

“I think that’s a primary motivation,” Eaton’s Genise says. “And in general if you look at fuel prices going up, it makes cylinder deactivation a salable point. Those two go hand in hand.”

Schaeffler’s INA division has exclusive agreement to market Fiat’s MultiAir valvetrain technology.

The technology idles unneeded cylinders during light-load driving cycles, generally boosting fuel economy between 6% and 12%.

Eaton’s CD system in GM’s 5.3L V-8 – a contract shared with Delphi Corp. – is marketed as Active Fuel Management.

Half the cylinders have unique 2-piece valve lifters, which incorporate two telescoping sections that can collapse into one another. An oil-pressure-activated locking pin in the lifters is engaged or disengaged – on command from the engine controller – based on driving conditions.

To deactivate half the cylinders, hydraulic pressure is used to unlock the pin, enabling the valve lifters' two sections to freely telescope into one another. As a result, camshaft motion is not translated to the pushrod, meaning intake and exhaust valves remain closed, until a throttle input causes them to reopen.

Looking forward, GM has hinted the 1.4L DOHC turbocharged I-4 in the new Chevrolet Cruze will offer AFM.

For Chrysler’s Multi-Displacement System on the 5.7L Hemi V-8 – available in many Chrysler Group vehicles – INA manufactures specially designed valve lifters that can selectively decouple the cam lift event from the respective poppet valves via electro-hydraulic actuation.

For new, high-revving OHC engines, Eaton and Schaeffler are introducing valvetrains that can operate with significantly more variability, even including CD if desired.

Eaton says its new variable valve-lift system can improve both fuel economy and power delivery, simply by switching valve-lift profiles. Combined with existing cam-phaser technology, for instance, the system can improve fuel economy up to 7%.

The technology switches modes the same way as the CD rocker arm and can be interchangeable, enabling different engines for diverse markets merely by changing the valvetrain components.

For customers who only want CD on future OHC engines, Schaeffler offers deactivating pivot elements.

But Zito argues that full variability of the valvetrain is the better route to achieve CD, while getting better performance and fuel economy, without a huge cost premium or the deactivating pivot element.

“If you can get deactivation for just a little more money because you put in all this other (valvetrain) variability, then the auto makers would take it,” he says.

As the supplier of Fiat Automobiles SpA’s MultiAir induction technology, Schaeffler has broad knowledge of fully variable valvetrains. Fiat pioneered the technology, introduced late last year in the Alfa Romeo MiTo in Europe and expected on as many as 1 million Fiat engines annually.

The first MultiAir engine arrives in the U.S. at the end of this year when the Fiat 500 goes on sale, powered by a 1.4L FIRE engine being built in Dundee, MI.

In addition, sources say Chrysler will offer MultiAir on a 2.4L 4-cyl. in midsize sedans and is considering it for the all-new 3.6L Pentastar DOHC 60-degree V-6 in the redesigned Jeep Grand Cherokee and other models. No word yet on whether those engines will integrate CD.

Through its relationship with Fiat, Schaeffler’s INA unit has exclusive rights to market the technology under the Uni-Air brand name to other auto makers, including supply of the patented valve actuators, solenoid valves and electronics.

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