Dynamic Skip Fire Engine Control for Fuel Efficiency
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Solution Overview
Problem
Current engine technologies, particularly in internal combustion engines, face challenges in achieving optimal fuel efficiency due to limitations in varying engine displacement, with conventional methods offering only a few fixed displacement modes and not adequately addressing the need for finer control of torque output, especially in autonomous driving vehicles.
Innovation Solution
The implementation of skip fire engine control and dynamic firing level modulation techniques, which allow for the determination of alternative engine torques and operational displacements that offer better fuel economy while maintaining performance, by selectively skipping cylinder firings and adjusting firing fractions based on real-time conditions, including vehicle speed, gear, and accessory loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional variable displacement engine control is used to deactivate a group of cylinders substantially simultaneously, then the engine can operate in fixed displacement modes, but the control granularity is coarse and fuel efficiency cannot be optimized further
Solution Approach 1:
The patent segments the cylinder deactivation control into individual cylinder-level decisions rather than group-level deactivation. Each cylinder can be independently controlled to fire or skip firing based on real-time conditions, enabling fine-grained control of effective displacement and optimizing fuel efficiency beyond conventional fixed modes
Solution Approach 2:
The patent implements dynamic skip fire control where the firing pattern of each cylinder is adjusted in real-time based on current operating conditions. This dynamic adjustment allows the engine to continuously optimize fuel efficiency by selecting the most appropriate firing pattern, transitioning smoothly between different effective displacement levels rather than being constrained to fixed modes
2Adaptability or versatility
If skip fire engine control is used to selectively skip cylinder firings, then finer control of effective displacement is achieved, but the complexity of determining optimal firing patterns increases
Solution Approach 1:
The patent pre-determines multiple candidate firing patterns with different effective displacement levels before real-time operation. During operation, the system selects from these pre-planned patterns based on current conditions, reducing the real-time computational burden while maintaining fine-grained control capability
Solution Approach 2:
The patent implements feedback mechanisms where the actual performance and operating conditions are continuously monitored, and the firing pattern selection is adjusted accordingly. This feedback loop enables the system to adapt to changing conditions while using the pre-determined patterns as a foundation, balancing adaptability with control complexity
3Use of energy by moving object
If engine torque output is reduced to improve fuel efficiency, then fuel consumption decreases, but the torque availability may be insufficient for operational demands
Solution Approach 1:
The patent changes the effective displacement parameter dynamically by selecting different firing patterns, allowing the engine to operate at lower displacement levels for fuel efficiency when full torque is not needed, while maintaining the capability to transition to higher displacement modes when torque demands increase
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables significant fuel savings by optimizing engine displacement and torque output, potentially reducing fuel consumption by up to 10% through the use of alternative firing fractions and torque levels, while ensuring acceptable noise, vibration, and harshness (NVH) characteristics, particularly beneficial for autonomous driving scenarios.
Implementation Method 1
Internal combustion engines typically have a plurality of cylinders or other working chambers where combustion occurs
Data Source
AI summary
The present invention relates generally to techniques for improving fuel efficiency of a vehicle powered by an internal combustion engine capable of operating at various displacement levels. An autonomous driving unit or cruise controller selects when possible an engine torque output that corresponds to a fuel efficient displacement level. The resultant vehicle speed profile and NVH level is acceptable to vehicle occupants.