Variable Displacement Engine Cylinder Control for NVH Management
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Solution Overview
Problem
Variable displacement engines face limitations in fuel economy gains due to noise, vibration, and harshness (NVH) constraints, which reduce the available window for operation and lead to unnecessary cylinder activation, decreasing fuel efficiency.
Innovation Solution
A method is implemented to control engine stability using vehicle acceleration sensors to identify and mitigate engine vibration, allowing for adaptive cylinder reactivation and deactivation, thereby improving fuel economy by extending the operating conditions of partial-cylinder mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If cylinder deactivation is used to improve fuel economy, then fuel efficiency increases, but noise, vibration, and harshness (NVH) increase
Solution Approach 1:
The system dynamically adjusts the number of active cylinders based on real-time operating conditions (vehicle speed, load, temperature). The engine transitions between different cylinder activation states (e.g., 4-cylinder, 2-cylinder, or 0-cylinder modes) to optimize fuel economy while maintaining acceptable NVH levels through adaptive control
Solution Approach 2:
The system changes operational parameters including cylinder deactivation timing, valve timing, and injection strategies to manage NVH characteristics. By adjusting these parameters, the system can operate with fewer cylinders during conditions where NVH is less critical while maintaining fuel efficiency
2Object-affected harmful factors
If the engine is calibrated for worst case NVH conditions, then NVH is reduced, but the available window for VDE operation decreases
Solution Approach 1:
The system uses feedback from sensors monitoring vehicle speed, engine load, and operating conditions to dynamically determine when cylinder deactivation is appropriate. This feedback mechanism allows the system to operate in VDE mode during conditions where NVH is acceptable while automatically transitioning to full cylinder operation when NVH becomes critical
Solution Approach 2:
Rather than using a static calibration for worst-case NVH, the system dynamically adapts its operation based on real-time conditions. The available window for VDE operation expands during conditions where NVH is less sensitive (e.g., steady-state cruising) and contracts when NVH becomes critical, optimizing both comfort and fuel economy
3Object-affected harmful factors
If the degree of continuation parameter is used to discontinue partial-cylinder mode, then NVH is controlled, but fuel economy gains are reduced due to unnecessary cylinder activation
Solution Approach 1:
The system continuously monitors operating conditions and provides feedback to the control system. When conditions indicate that NVH will not be problematic (e.g., steady-state operation at appropriate speed/load), the system maintains cylinder deactivation. When conditions change to indicate potential NVH issues, the system transitions to full cylinder operation, avoiding unnecessary activation and maintaining fuel economy
Solution Approach 2:
The system dynamically adjusts cylinder activation based on real-time operating conditions rather than using a fixed threshold. This allows the engine to operate in partial-cylinder mode during extended periods when conditions are favorable, maximizing fuel economy while only activating all cylinders when truly necessary for NVH control
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 enhances fuel economy by enabling the engine to operate with fewer cylinders over extended conditions while reducing NVH, thus optimizing the window for variable displacement engine operation.
Implementation Method 1
engine vibration can cause the vehicle chassis to exhibit acceleration. In particular, the engine firing-frequency component of the vehicle acceleration can be used to identify undesirable engine vibration
Data Source
AI summary
A method for operating an engine of a vehicle, the engine having one or more deactivatable cylinders, the method including controlling the stability of a vehicle in response to vehicle acceleration, and reactivating or deactivating combustion in at least a cylinder in response to vehicle acceleration.