Speed Sensor Short Circuit Diagnosis via Current Monitoring
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Solution Overview
Problem
Current motor vehicle engine control systems face challenges in accurately diagnosing short circuits in speed/position sensors, as they cannot distinguish between a short circuit with the sensor's power supply and another power supply, such as the battery power supply, leading to incorrect diagnostics.
Innovation Solution
A method is introduced that involves detecting a short circuit between the speed/position sensor's output and power supply, and performing an excess current consumption test to determine if the short circuit is within the sensor's power supply or another power supply, such as the engine control's power supply, without requiring additional hardware components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a short circuit detection is performed in the speed/position sensor output, then the diagnostic capability is improved, but the ability to distinguish between different power supply short circuits deteriorates
Solution Approach 1:
The diagnostic method segments the short circuit detection into two distinct phases: first detecting the presence of a short circuit at the sensor output, then separately testing for excess current consumption to determine the specific location. This segmentation allows the system to maintain both detection accuracy and location information without requiring additional hardware.
Solution Approach 2:
The engine control unit acts as an intermediary that coordinates between the short circuit detection and the excess current consumption test. By using the existing power supply current monitoring capability as an intermediary measurement, the system can infer the location of the short circuit without adding dedicated diagnostic hardware components.
2Measurement precision
If additional diagnostic functions are added to distinguish power supply short circuits, then the diagnostic accuracy is improved, but the device complexity increases
Solution Approach 1:
The engine control unit's existing current monitoring functionality is made multi-functional by using it both for normal power supply management and for diagnostic purposes. The same power supply lines and current sensing circuits used for operation are also used to detect excess current consumption during diagnostics, eliminating the need for separate diagnostic hardware.
Solution Approach 2:
The diagnostic system performs self-diagnosis by utilizing the inherent current consumption characteristics of the power supply circuitry. The system monitors its own power supply current to detect abnormalities, allowing the speed/position sensor and engine control to diagnose their own faults without external diagnostic equipment.
Data Source
AI summary
Disclosed is a method for diagnosing a speed/position sensor of an internal combustion engine, of the type including a toothed wheel, which rotates as one with a shaft, and a matter detector, which is arranged so as to be fixed opposite the toothed wheel and controls a base of a transistor. The method includes: detecting a short circuit between an output of the speed/position sensor and a power supply; and testing for excess current consumption by a power supply of the speed/position sensor when the transistor is activated. If the test is positive, the short circuit is identified between the power supply of the speed/position sensor and the output of the speed/position sensor. Alternatively, if the test is negative, the short circuit is identified between another power supply and the output of the speed/position sensor.