Engine Firing Phase Transition Control
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Solution Overview
Problem
Existing engine technologies face challenges in managing firing sequence phase transitions during skip fire and cylinder output level modulation, particularly in ensuring consistent cylinder operation and minimizing noise, vibration, and harshness (NVH) issues during transitions between different firing fractions.
Innovation Solution
The implementation of a control method using a first-order sigma delta converter to dynamically adjust the firing sequence phase by adding offset values to an accumulator, ensuring that the desired set of cylinders fire consistently, and utilizing this approach to transition between different firing fractions while mitigating NVH effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic skip fire control is used to achieve finer control of effective engine displacement, then adaptability is improved, but noise, vibration, and harshness (NVH) increase during phase transitions
Solution Approach 1:
The system dynamically adjusts the phase of the firing sequence during skip fire operation. The controller monitors the current phase and actively transitions between different phase states (e.g., from firing every third cylinder to firing every fourth cylinder) based on operating conditions, enabling the engine to adapt its effective displacement dynamically while managing NVH characteristics through controlled phase changes
Solution Approach 2:
The invention utilizes phase transitions in the firing sequence as a controlled mechanism to change effective displacement. By transitioning the phase of which cylinders fire (e.g., changing from a pattern where cylinders 1,4,7 fire to where cylinders 2,5,8 fire), the system achieves variable effective displacement while the transition process itself is managed to minimize NVH impacts
2Adaptability or versatility
If the phase of the firing sequence is changed to achieve desired cylinder operation, then adaptability is improved, but the complexity of control increases
Solution Approach 1:
The controller implements feedback by monitoring the current phase of the firing sequence and comparing it to the desired phase. Based on this feedback, the controller determines when and how to transition between phases, automatically adjusting the firing pattern without requiring complex external intervention or manual control
Solution Approach 2:
The system performs self-service by automatically managing its own phase transitions. The controller independently determines the current phase state, identifies when a phase change is needed based on operating conditions, and executes the transition without external assistance, thereby managing the complexity internally while maintaining adaptability
Data Source
AI summary
Methods and controllers for dynamically altering the phase of a firing sequence during operation of an engine are described. The described methods and controllers are particularly useful in conjunction with cylinder output level modulation operation of an engine such as dynamic skip fire operation of the engine and/or multi-charge level operation of the engine.