Crankshaft Position Estimation for Faster Engine Start
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Solution Overview
Problem
Current methods for starting internal combustion engines require synchronization of the crankshaft position, which delays engine startup and increases pollutant emissions when fuel injection occurs before synchronization is complete, especially in indirect injection engines.
Innovation Solution
A method to estimate the angular position of the crankshaft prior to synchronization using events detected on camshaft and crankshaft targets, allowing for precise estimation of plausible positions without needing to detect a camshaft target event, using a formula to correlate events and reduce the angular window of possible positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronization is completed before fuel injection, then ignition timing precision is improved, but engine startup time increases and pollutant emissions increase
Solution Approach 1:
The patent performs preliminary fuel injection before synchronization is complete. By estimating the crankshaft position using camshaft target events and correlation formulas, the system enables injection to occur earlier than traditional methods, reducing startup time while maintaining acceptable timing precision for indirect injection engines
2Measurement precision
If synchronization is completed before fuel injection, then ignition timing precision is improved, but pollutant emissions increase
Solution Approach 1:
The patent performs preliminary fuel injection before synchronization is complete. By estimating the crankshaft position using camshaft target events and correlation formulas, the system enables injection to occur earlier than traditional methods, reducing startup time and associated pollutant emissions while maintaining acceptable timing precision for indirect injection engines
3Loss of time
If camshaft target events are used to estimate crankshaft position, then engine startup is accelerated, but measurement precision requirements increase
Solution Approach 1:
The patent uses feedback from camshaft target events to continuously refine the crankshaft position estimation. By correlating detected camshaft events with predefined profiles and updating the estimated position iteratively, the system achieves sufficient precision for injection timing without requiring full synchronization
Solution Approach 2:
The patent replaces the traditional mechanical synchronization requirement with an estimation system based on camshaft event detection and correlation algorithms. This substitution allows the engine to proceed with injection before mechanical synchronization is complete, reducing startup time while maintaining functional precision
Data Source
AI summary
A method for estimating the angular position of a crankshaft of a 4-stroke internal combustion engine prior to synchronization of the engine having a plurality of camshafts provided with a number n of targets (CAM_i) secured respectively to n camshafts, each target defining a plurality of events over one revolution of the camshaft to which it is secured, the crankshaft having a securely attached target (CRK) including a plurality of standard teeth and at least one reference tooth which define a plurality of events over one crankshaft revolution, the method including: estimating a range of plausible positions of the crankshaft prior to synchronization, at a given moment, from events detected on the n camshaft targets, correlated with events detected on the crankshaft target, as corresponding to the shortest angular window that is common to all the members of rank i using the following formula:Pos_Crk_est=⋂i=1i=n_CAMList_event_plaus_CAM_i+Dist_ang_CRK_since_last_event_CAM_i+Tolerances_i.