Skip Fire Engine Control for NVH Reduction
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Solution Overview
Problem
Conventional variable displacement engines face challenges in managing transitions between operational states, leading to undesirable noise, vibration, and harshness (NVH) issues, especially at higher torque levels, which results in inefficient fuel usage as the engine switches to higher cylinder modes prematurely.
Innovation Solution
Implementing skip fire engine control mechanisms that dynamically manage the firing and deactivation of working chambers, using algorithms and libraries to generate firing sequences that reduce NVH and facilitate smooth transitions between operational states, allowing the engine to remain in lower cylinder modes for longer periods, improving fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional variable displacement engine transitions between operational states are used, then the engine can switch between different cylinder modes, but undesirable noise, vibration, and harshness (NVH) issues occur especially at higher torque levels
Solution Approach 1:
The patent applies periodic action by implementing skip-fire operation patterns during transitions between cylinder modes. The engine control system alternates between firing and skipping combustion cycles in a periodic manner, which smooths out the torque delivery and reduces NVH during mode transitions while maintaining adaptability between different operational states.
2Power
If the engine switches to higher cylinder modes at higher torque levels, then torque demand is met, but fuel efficiency deteriorates due to premature switching from lower cylinder modes
Solution Approach 1:
The patent implements dynamics by using real-time monitoring and dynamic threshold adjustment for mode transitions. The control system continuously adapts the torque thresholds for switching between cylinder modes based on current operating conditions, allowing the engine to remain in fuel-efficient lower cylinder modes longer while still meeting torque demands through optimized skip-fire patterns during transitions.
3Object-affected harmful factors
If smooth transitions between operational states are implemented, then NVH is reduced, but the transition process becomes more complex requiring advanced control algorithms
Solution Approach 1:
The patent uses an intermediary approach by introducing predetermined transition profiles and lookup tables that store pre-calculated skip-fire patterns for different transition scenarios. This intermediary layer simplifies the real-time control logic while achieving smooth transitions, as the complex transition management is handled by pre-computed data rather than complex real-time algorithms.
Data Source
AI summary
A variety of methods and arrangements for managing transitions between operating states for an engine are described. In one aspect, an engine is operated in a particular operating state. A transition is made to another operating state. During that transition, the engine is operated in a skip fire manner.