Cylinder Deactivation Pattern for Camshaft Phasing
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Solution Overview
Problem
In engines with variable cam timing and cylinder deactivation, the deactivation of cylinders can lead to reduced camshaft phasing ability due to diminished torsional signatures, which affects engine performance.
Innovation Solution
An engine controller adjusts cylinder deactivation patterns to reactivate or deactivate cylinders based on camshaft torsional signatures, ensuring sufficient energy for camshaft phasing by optimizing the number and identity of active and inactive cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cylinders are deactivated to improve fuel economy, then fuel efficiency is improved, but camshaft phasing ability deteriorates due to diminished torsional signatures
Solution Approach 1:
The system dynamically adjusts cylinder deactivation patterns based on real-time camshaft phasing requirements. The engine control system monitors phasing demands and selectively activates or deactivates cylinders to maintain sufficient torsional signatures on the camshaft, enabling the camshaft phaser to maintain proper timing while still achieving fuel economy benefits when conditions permit deactivation.
Solution Approach 2:
The system changes the operational parameters of individual cylinders by switching between active and deactivated states based on specific conditions. By carefully selecting which cylinders to deactivate and under what conditions, the system optimizes the balance between fuel economy (reduced pumping losses) and maintaining adequate torsional energy for camshaft phasing operations.
2Adaptability or versatility
If a vane type cam phaser is used for variable cam timing, then cam timing adjustment is enabled, but the phaser's phasing ability is reduced when torsional input is diminished by cylinder deactivation
Solution Approach 1:
The system dynamically manages the interaction between the cam phaser and cylinder deactivation by monitoring phasing demands. When phasing is required, the system ensures adequate torsional input is available to the phaser by adjusting which cylinders remain active, allowing the vane type phaser to maintain its timing adjustment capability while preventing phasing degradation.
Solution Approach 2:
The engine control system employs feedback mechanisms to monitor camshaft phasing requirements and adjust cylinder deactivation patterns accordingly. This feedback loop ensures that the torsional signature delivered to the cam phaser remains sufficient to maintain proper phasing operation, preventing the phaser from losing its ability to adjust timing when cylinder deactivation is active.
3Loss of energy
If cylinder deactivation pattern is optimized for fuel economy, then fuel efficiency is improved, but camshaft torsional signature is reduced affecting engine performance
Solution Approach 1:
The system optimizes engine performance by dynamically changing the operational parameters of cylinders based on real-time conditions. By selectively activating or deactivating specific cylinders rather than using fixed deactivation patterns, the system maintains adequate torsional signatures for camshaft phasing while still achieving fuel economy benefits, thereby preserving overall engine performance across varying operating conditions.
Solution Approach 2:
The system transitions from static cylinder deactivation patterns to dynamic patterns that adapt to instantaneous engine conditions. This dynamic approach allows the engine to maintain optimal performance by ensuring sufficient torsional energy is available for camshaft phasing operations while still capturing fuel economy benefits when deactivation is appropriate, resolving the trade-off between fuel efficiency and performance.
Data Source
AI summary
Methods and systems are provided for adjusting a cylinder deactivation pattern to improve camshaft phasing. In response to a request for actuating a camshaft phaser of a variable cam timing device, a cylinder deactivation pattern is adjusted by reactivating cylinders that were deactivated while deactivating other cylinders that were active, while maintaining a total number of deactivated/active cylinders. Cylinders are selected for reactivation or deactivation based on their individual camshaft torsion signatures so that sufficient cam torque is generated to actuate the phaser and provide the requested phasing.