Variable Valve Timing Control via Minimum Speed Positions
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Solution Overview
Problem
Existing variable valve timing systems in heat engines are deactivated when a position sensor fails, leading to inefficiencies and increased pollution, as they rely on target and position sensor information for camshaft control.
Innovation Solution
A method that controls variable valve timing systems by determining a reference minimum speed position of the crankshaft to calculate and adjust the phase shift of camshafts, allowing for continuous operation without camshaft targets or position sensors, using a computer program to implement this method and store necessary instructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor and target are used to control camshaft phase shift, then the variable valve timing system can be controlled precisely, but the system becomes complex and vulnerable to sensor failures
Solution Approach 1:
The invention extracts and eliminates the position sensor and target components from the variable valve timing system. Instead of using direct camshaft position sensing, the system uses crankshaft position sensing combined with calculated phase relationships to determine camshaft positions, thereby removing the vulnerable and complex sensor-target assembly while maintaining control precision
Solution Approach 2:
The invention introduces an intermediary computational approach where the microcontroller calculates camshaft phase positions based on crankshaft position data and stored phase relationships. This computational intermediary replaces the direct sensing approach, reducing hardware complexity while preserving measurement precision through mathematical derivation rather than direct physical measurement
2Measurement precision
If a position sensor is used for camshaft control, then accurate phase shift control is achieved, but the system reliability decreases when sensor failures occur
Solution Approach 1:
The invention performs preliminary action by pre-storing the relationship between crankshaft position and camshaft phase shift in the microcontroller's memory. This allows the system to quickly and accurately calculate camshaft positions from crankshaft data without requiring real-time sensor feedback on camshaft position, thereby maintaining reliability even when position sensors fail
Solution Approach 2:
The invention changes the measurement parameter from direct camshaft position (which requires a position sensor) to crankshaft position combined with phase relationship calculations. This parameter transformation eliminates the need for vulnerable camshaft position sensors while maintaining accurate phase shift control through computational methods
3Device complexity
If camshaft targets and position sensors are removed, then system cost and complexity are reduced, but the ability to control variable valve timing is lost
Solution Approach 1:
The invention replaces the mechanical sensing system (camshaft targets and position sensors) with an electronic computational system. The microcontroller uses crankshaft position data and stored phase relationships to calculate and control camshaft positions, substituting direct mechanical measurement with electronic computation while maintaining full variable valve timing control capability
Solution Approach 2:
The invention makes the crankshaft position sensor serve multiple functions: it provides both the primary timing reference and the basis for calculating camshaft positions. This multi-functionality eliminates the need for separate camshaft position sensors, reducing system complexity while preserving complete variable valve timing control through the microcontroller's computational capabilities
Data Source
AI summary
A method for controlling a variable valve timing system using minimum speed positions. The minimum speed positions allow the movement and the position of the various camshafts to be controlled.