Vehicle ECU Wake-Up Circuit ON Sticking Malfunction Detection
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Solution Overview
Problem
Existing malfunction detection methods for power relays in vehicle power supply circuits often result in erroneous determinations due to changes in stored information, leading to potential CPU damage from repeated reset operations.
Innovation Solution
The proposed method involves an electronic control device with a wake-up circuit that monitors actual voltage and operation states to detect ON sticking malfunctions, preventing reliance on stored information for malfunction determination and reducing CPU reset repetitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If malfunction detection is performed based on stored information, then malfunction detection capability is improved, but erroneous determinations occur due to information changes leading to CPU damage
Solution Approach 1:
The system performs preliminary actions by storing voltage threshold values (ON threshold and OFF threshold) in advance in the controller's storage unit. These pre-stored thresholds enable the controller to compare against actual voltages during operation without needing to store historical malfunction information, thus preventing erroneous determinations while maintaining detection capability
Solution Approach 2:
The patent introduces voltage threshold values as intermediary reference standards between the power supply voltage and the controller's malfunction determination logic. By using these intermediary threshold values stored in the storage unit, the system avoids directly storing and relying on historical malfunction information that may become erroneous, thus preventing CPU damage from repeated reset operations
2Measurement precision
If real-time voltage monitoring is implemented, then malfunction detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the voltage monitoring function with the existing controller by integrating a voltage detection circuit and storage unit into the controller structure. This allows the controller to simultaneously perform its normal control functions and monitor power supply voltage against stored thresholds, improving measurement precision without significantly increasing overall device complexity
Solution Approach 2:
The controller performs self-diagnosis by comparing the detected power supply voltage against its own pre-stored threshold values. This self-service approach allows the controller to autonomously detect malfunctions without requiring external monitoring equipment, thereby improving measurement precision while avoiding additional complexity from separate monitoring systems
Data Source
AI summary
A malfunction detection method detects a malfunction in an electronic control device. The electronic control device includes a normal power supply terminal connected to a normal power supply mounted on a vehicle, a starting power supply terminal connected to a starting power supply, a controller activated by supply of a normal voltage, and a wake-up circuit having a wake-up switch to open and close a power supply path from the normal power supply terminal to the controller. The wake-up circuit turns on the wake-up switch when a starting voltage input to the starting power supply terminal is equal to or greater than an ON threshold. The malfunction detection method includes determining by the controller that the wake-up switch has an ON sticking malfunction when the normal voltage is equal to or greater than a threshold and the starting voltage is less than the ON threshold.