Crankshaft Position Tracking for Fast Engine Restart
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Solution Overview
Problem
Existing engine management systems face desynchronization issues during engine stop and start cycles, leading to prolonged synchronization phases due to the increase in tooth period, which exceeds measurement capabilities, especially in 'Stop & Start' applications requiring frequent restarts.
Innovation Solution
A method to determine the absolute angular position of a crankshaft target by continuously tracking the number of the tooth passing in front of the sensor during engine stoppage, utilizing this information for rapid synchronization upon restarting, and employing a Bresenham algorithm for high-resolution signal interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the engine stops and starts frequently in Stop & Start applications, then the productivity is improved, but the synchronization phase duration increases due to tooth period increase exceeding measurement capabilities
Solution Approach 1:
The patent applies preliminary action by continuously tracking the tooth number during engine stoppage before restart is needed. The processor maintains knowledge of which tooth is currently detected, so when the engine restarts, the system already has the information needed to quickly resynchronize without waiting for the tooth period to be measured again from scratch.
Solution Approach 2:
The patent uses feedback by continuously monitoring and recording the tooth number during the stop phase, then using this recorded information as feedback to accelerate the synchronization process during restart. The processor leverages the feedback from the stop period to reduce the synchronization time needed during the restart period.
2Measurement precision
If the tooth period increases during engine stoppage, then the measurement precision is maintained, but the synchronization phase duration increases due to exceeding measurement capabilities
Solution Approach 1:
The system performs preliminary tracking of the tooth number during the stop phase when the tooth period is extended. By maintaining continuous count of the tooth number during this preliminary period, the system prepares synchronization data in advance, allowing rapid resynchronization during restart without being constrained by the extended measurement period.
Solution Approach 2:
The patent applies dynamics by adapting the synchronization strategy based on the engine's operational state. During stoppage, the system dynamically switches to tooth-number tracking mode to maintain precision despite increased tooth period. During restart, it dynamically switches back to standard synchronization mode, leveraging the preliminary tracking data to achieve fast resynchronization.
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
Significantly reduces the synchronization phase duration, enabling faster engine restarts and maintaining system synchronization even at low engine speeds, thus improving the efficiency of 'Stop & Start' applications.
Implementation Method 1
The signal delivered by the sensor is an analog signal in the case of a variable-reluctance sensor
Implementation Method 2
employing a Bresenham algorithm for high-resolution signal interpolation
Data Source
AI summary
A method for determining an absolute angular position of a crankshaft target of an internal combustion engine, including a plurality of teeth for which at least one signal is acquired representing the passage of each tooth in front of a sensor as a function of time comprising:i. generating during a phase with the engine running an absolute angular position from the at least one signal and from a period of a tooth;ii. continuously determining during a phase of stopping the engine when determination of the period is not possible, a number of teeth passing in front of the sensor; andiii. during a phase of restarting the engine, using a number of teeth to reduce the cycle synchronization time.