US 12,146,447 B1
Multimode engines with advanced valvetrain systems and methods of use
Shengrong Zhu, Ann Arbor, MI (US); Kyoung Pyo Ha, Gyeonggi-do (KR); Mark Shirley, Albion, MI (US); Ankith Ullal, Superior Township, MI (US); Nam Kyun Kang, Superior Township, MI (US); Jeffrey Hollowell, Commerce, MI (US); Nicholas Fantin, Ann Arbor, MI (US); and Vincent Costanzo, Superior Township, MI (US)
Assigned to Hyundai Motor Company, Seoul (KR); and Kia Corporation, Seoul (KR)
Filed by Hyundai Motor Company, Seoul (KR); and Kia Corporation, Seoul (KR)
Filed on Aug. 4, 2023, as Appl. No. 18/365,596.
Int. Cl. F02D 13/02 (2006.01); F02P 5/04 (2006.01)
CPC F02D 13/0265 (2013.01) [F02P 5/045 (2013.01); F02D 2200/1006 (2013.01); F02D 2200/1012 (2013.01); F02D 2250/21 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method of improving engine low load performance, comprising:
performing a negative valve overlap (NVO) mode of operation, using an early exhaust valve closing (EVC) timing that is earlier than an intake valve opening (IVO) timing and creates an NVO during a gas exchange top dead center, to compress in-cylinder gas and increase overall gas temperature for improved fuel vaporization, mixing, and reforming before a fuel-air mixture is burnt;
running an engine in a low temperature combustion-spark assisted (LTC-SA) mode with an approximately wide-open-throttle (WOT); and
when a rate of change (ROC) in the engine speed and a load is less than or equal to a predefined ROC (ROCmax):
transitioning from a spark ignition (SI) mode to an LTC-SA mode; or
transitioning from the LTC-SA mode to the SI mode; and
when the ROC is greater than the ROCmax:
when in the SI mode:
adjusting a throttle and a boost; and
adjusting a spark timing and a fueling strategy.