A 1.0-L three-cylinder gasoline engine may not seem a likely candidate for cylinder deactivation, but Ford is doing just that with diminutive EcoBoost triple. Production is slated to begin by early 2018 with the technology—which turns the engine into a 670-cc twin under certain load conditions—expected to deliver up to a 6% fuel saving with associated CO2 emissions reduction.
Claimed as a “world first” for a triple, Ford believes its deactivation technology will meet refinement requirements and confound skeptics that such a system applied to a 3-cylinder engine would be unacceptable in NVH terms.
The EcoBoost effectively enters twin-cylinder operation in some cruise and light engine load conditions. Depending on throttle position it reverts to 3-cylinder operation when conditions change—in a claimed 14 ms.
According to Bob Fascetti, Vice President Global Powertrain Engineering, the development demonstrates the continuing potential of gasoline engine technology.
Ford worked with Schaeffler Group on the variable displacement system, which will operate up to 4500 rpm, using oil pressure to activate a special valve rocker to interrupt the connection between the camshaft and one cylinder. Ford engineers reveal that a single-piece camshaft module similar to that used for its EcoBlue diesel provides added space in the cylinder head for new oil channels and the valve switching components.
Further changes to the regular engine include the use of a new dual-mass flywheel and a vibration damping clutch disc to help counter engine oscillations set up in twin-cylinder mode that would otherwise manifest vibration, particularly at low revs. Intake and exhaust valves are closed when the system is active, trapping gases to provide a “spring effect” to help balance forces across all cylinders and to retain temperatures inside the cylinder to ensure fuel efficiency when reactivated, engineers report.
Also included in the system are new engine mounts, drive shafts and suspension bushes, a new camshaft chain and metal-injection-molded valve rockers.
About 20% of all Ford models sold in Europe during 2015 used the 1.0-L triple, which can be specified for 11 models sold there.
Ford gave no indication as to what the cylinder deactivation system will add to unit cost, nor how much, if any, of that would be passed to the end-user.