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Patent: cylinder shutoff + lift

by David Zatz on

A recently granted Chrysler patent shows a system that combines cylinder deactivation and variable valve lift. Unlike the Hemi V8, it uses the rocker arms rather than the lifters, and is designed for overhead cam engines. This means it would be more effective on the company’s forthcoming four or six cylinder engines, or a V8 setup loosely based on the Pentastar V6 architecture.

AutoTechnician, who discovered the patent, noted that Chrysler has patented MultiAir heads for the Pentastar V6, but years ago, sources told Allpar that Chrysler would test the system but might not use it due to the high cost of MultiAir and the effectiveness of the cheaper cam phasing system Chrysler already has. The most recent word from within Auburn Hills is that the Pentastar Upgrade (PUG) will not have MultiAir.

The advantage of cylinder deactivation (or MDS as Chrysler calls it — Multiple Displacement System) is that some cylinders can be shut off when they are not needed. In Hemi V8 engines, four cylinders are shut off but can be reactivated within fractions of a second. Honda has a similar system on V6 engines, cutting two cylinders.

Chrysler valve lifter - cylinder deactivation systemThe patent application, originally filed in December 2011 and approved on January 27, 2015, credits Ira R. Stoody of Roseville, Michigan, as the inventor; the assignee is listed as Chrysler Group LLC.  Credit was given to Delphi’s system, used by General Motors, and to other past patents.

According to the patent, the rocker arm assembly can either reduce valve lift or shut off the cylinder entirely; in one position, inner and outer portions are locked together to provide traditional valve lift, while in another, the inner portion can rotate to cut lift or shut it entirely. Bearings on both sections keep the system in contact with the camshaft, using a hydraulic system to move between locked and unlocked positions. Camshaft phasing is presumably used to vary valve timing.

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