Engine Controller Firing Fraction Coordination During Transmission Shifts
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Solution Overview
Problem
During transmission shifts in internal combustion engines, undesirable NVH (Noise, Vibration, and Harshness) issues often occur due to changes in firing fractions, particularly in skip fire and other dynamic cylinder output level modulation operations, which existing technologies fail to adequately manage.
Innovation Solution
Implementing control schemes where an engine controller coordinates firing fraction transitions with transmission shifts by issuing 'do-not-shift' instructions and using transition protocols that involve skip fire or cylinder output level modulation, ensuring firing fraction changes occur before or during specific phases of gear shifts to minimize NVH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If firing fraction transitions are implemented during transmission shifts to improve fuel efficiency and torque control, then engine displacement variability is improved, but NVH (Noise, Vibration, and Harshness) characteristics deteriorate
Solution Approach 1:
The engine controller receives transmission shift information in advance and determines a transition protocol before the shift occurs. This allows the firing fraction transition to be planned and executed in coordination with the transmission shift timing, preventing NVH issues that would arise from uncoordinated transitions during the shift event.
Solution Approach 2:
The system dynamically adjusts the firing fraction transition protocol based on real-time transmission shift information. The transition timing and protocol are not fixed but are adapted dynamically according to the actual shift timing and duration, allowing optimal coordination between engine firing fraction changes and transmission gear shifts to minimize NVH.
2Object-affected harmful factors
If firing fraction changes are coordinated with transmission shifts to reduce NVH, then NVH characteristics are improved, but control system complexity increases
Solution Approach 1:
The engine controller acts as an intermediary that receives transmission shift information and translates it into appropriate firing fraction transition protocols. This intermediary role coordinates the two subsystems (transmission and engine) without requiring direct complex integration, simplifying the overall control architecture while achieving NVH reduction.
Solution Approach 2:
The system uses feedback from transmission shift information to adjust the firing fraction transition protocol. The engine controller continuously monitors transmission shift events and adjusts its firing fraction control strategy accordingly, creating a closed-loop control system that reduces NVH while maintaining manageable complexity through adaptive rather than purely predetermined control logic.
Data Source
AI summary
Methods and controllers for coordinating firing fraction transitions that occur in conjunction with transmission shifts are described. In one aspect, an engine controller transmits a do-not-shift instruction to a transmission controller based at least in part on a determination that a particular type of firing fraction transition is desired. The firing fraction transition is then implemented using a skip fire transition protocol. In this manner, the transmission is affirmatively prevented from shifting during the firing fraction transition. The described approaches are well suited for use in connection with transitions to DCCO or DFCO operation.