FCA US’ Andrew Morris and Craig DeYoung created a system to reduce the compression ratio while you’re starting your car, to cut back on the starter’s workload. The system uses the engine’s cam phaser system to increase valve lift to the point that compression falls to 5:1-6:1 from the usual roughly-10:1.
While starting an engine seems to only happen once per trip, engine stop-start systems have become a common way to cut fuel use by shutting the engine instead if idling it while waiting for a traffic light to change or a train to pass. Valve control systems have already been used to make restarting the car easier and quieter, e.g. by changing the opening duration or by changing its timing.
A cam with multiple profiles or a control system such as MultiAir can be quite expensive and have performance issues, e.g. hurting emissions or economy. This invention uses a simpler setup—cam and phaser motor. The phaser can advance the intake cam between 120 crank degrees and 150°, and can set up an “early valve closing Miller-style strategy.”
The patent application was filed just last year—March 2023—and published in early January 2024. If nothing else, it shows that the former Chrysler is still working on ICE (or at least gasoline) engines.