Crank Signal Error Detection Using Cam Interval Counting
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Solution Overview
Problem
Existing methods for detecting crank signal errors in internal combustion engines, such as those based on time intervals, may fail to detect intermittent or occasional missing pulses, leading to potential engine control issues.
Innovation Solution
A method that increments a crank tooth counter in response to detected crank signals and compares it to an expected value using a cam signal, indicating an error if the counter is not substantially equal, allowing for adjustments based on cam interval and tolerance limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a time-based approach is used to detect crank signal errors, then the detection method is simple to implement, but it fails to detect intermittent or occasional missing pulses
Solution Approach 1:
The patent replaces the time-based detection method with a tooth counter-based method. Instead of measuring time intervals between crank pulses, the system counts the number of teeth detected by the crank sensor and compares the count to an expected value derived from cam sensor intervals. This substitution enables reliable detection of intermittent missing pulses while maintaining implementation simplicity.
2Reliability
If the crank sensor becomes damaged or the crank signal becomes inaccurate, then the ECU should detect the problem, but time-based methods cannot detect occasional errors
Solution Approach 1:
The patent introduces a tooth counter as an intermediary element between the crank sensor and the ECU's error detection logic. The tooth counter accumulates pulse counts over cam sensor intervals, providing a more robust measurement that filters out occasional noise or intermittent failures. This intermediary mechanism improves signal accuracy monitoring without significantly increasing device complexity, as it uses existing sensors and adds only counting logic.
Data Source
AI summary
A method of detecting a crank signal error that includes incrementing a crank tooth counter in response to detecting a crank signal, comparing the crank tooth counter to an expected value when a cam signal is detected, and indicating a crank signal error if the crank tooth counter is not substantially equal to the expected value. This method is advantageous because a cam interval used to determine when to start and stop counting crank tooth pulses is automatically adjusted for variations in engine speed, while the prior art time based methods must adjust the time interval for variations in engine speed.