Adaptive Torque Mitigation in Skip Fire Engine Control
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Solution Overview
Problem
Internal combustion engines generate unwanted noise, vibration, and harshness (NVH) due to the combustion process and firing of cylinders, which are challenging to mitigate effectively using existing technologies.
Innovation Solution
A dynamic firing level control system using a matched basis function control algorithm to generate a smoothing torque applied to the powertrain, which cancels out variations in torque generated by the skip fire firing sequence, reducing NVH through an electric motor/generator and energy storage/capture/release devices like batteries and capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If skip fire firing sequence is used to improve fuel efficiency, then fuel consumption is reduced, but noise, vibration and harshness (NVH) increases
Solution Approach 1:
The control system generates a smoothing torque signal in advance that is designed to counteract the torque variations and vibrations produced by the skip fire firing sequence. This preliminary anti-action allows the engine to operate in fuel-efficient skip fire mode while the smoothing torque preemptively neutralizes the resulting NVH before it propagates through the powertrain.
Solution Approach 2:
An auxiliary torque source/sink acts as an intermediary between the engine and the powertrain. This intermediary component generates or absorbs torque as needed to smooth out the irregular torque pulses from skip fire operation, thereby decoupling the fuel efficiency benefits of skip fire from its NVH penalties.
2Object-affected harmful factors
If dynamic firing level modulation is used to reduce NVH, then noise and vibration are reduced, but system complexity increases
Solution Approach 1:
The system dynamically adjusts the firing level modulation depth and frequency based on real-time operating conditions such as engine load, speed, and measured NVH levels. This dynamic adaptation allows the system to achieve effective NVH reduction across varying operating conditions without requiring a completely complex control architecture for every scenario.
Solution Approach 2:
The control system incorporates feedback from NVH sensors and engine operating parameters to continuously adjust the firing level modulation strategy. This feedback mechanism allows the system to learn and adapt to different operating conditions, reducing NVH effectively while avoiding the need for overly complex predetermined control logic.
3Object-affected harmful factors
If smoothing torque is applied to cancel torque variations, then NVH is reduced, but energy consumption increases
Solution Approach 1:
The control system applies smoothing torque selectively rather than continuously. It monitors NVH levels and engine operating conditions, applying torque cancellation only when and where needed to achieve acceptable NVH levels. This partial action approach avoids the excessive energy consumption that would result from continuous full-strength smoothing torque application.
Solution Approach 2:
The system dynamically changes parameters such as the amplitude and frequency of the smoothing torque based on real-time NVH measurements and engine operating conditions. By adjusting these parameters, the system minimizes the energy required for NVH reduction while maintaining effectiveness across different operating scenarios.
Data Source
AI summary
A variety of methods and arrangements for reducing noise, vibration and harshness (NVH) in a skip fire engine control system are described. In one aspect, a firing sequence is used to operate the engine in a dynamic firing level modulation manner. A smoothing torque is determined by adaptive control that is applied to a powertrain by an energy storage/release device. The smoothing torque is arranged to at least partially cancel out variation in torque generated by the firing sequence. Various methods, powertrain controllers, arrangements and computer software related to the above operations are also described.