ECU Timer Cross-Check During Key-Off Diagnosis
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Solution Overview
Problem
Conventional techniques cannot diagnose the normal operation of a timer during the key-off time period, leading to potential abnormal diagnosis of vehicle parts, as they fail to detect temporary stops or defects occurring only during this period.
Innovation Solution
An electronic control device with a first power supply unit that includes a first timer, a diagnostic timer, and a timer diagnosis unit, which compares timer values at predetermined intervals during the key-off time period to determine if the timer is operating normally, using a battery voltage as a power supply to ensure continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the timer operates only during key-on time period to perform diagnosis, then the device complexity is reduced, but the reliability of timer diagnosis during key-off time period deteriorates
Solution Approach 1:
The timer operation is segmented into two distinct modes: a first timer that operates during key-off time period for continuous time measurement, and a second timer that operates during key-on time period for vehicle part diagnosis. This segmentation allows each timer to specialize in specific operational phases, enabling reliable timer diagnosis during key-off period while maintaining overall system functionality.
Solution Approach 2:
A timer diagnosis unit is introduced as an intermediary component that compares the operation status of the first timer with the second timer. This intermediary mechanism enables indirect verification of the first timer's accuracy by referencing the second timer's known accurate operation during key-on period, thereby ensuring timer reliability without requiring the first timer to operate independently in isolation.
2Measurement precision
If the timer measures time during key-off period continuously, then the measurement precision is improved, but the difficulty of detecting temporary stop or defect during key-off period increases
Solution Approach 1:
The timer diagnosis unit implements a feedback mechanism that continuously monitors the first timer's operation by comparing its measured time against the second timer's time during key-on period. This feedback loop enables real-time detection of any deviations, temporary stops, or defects in the first timer's continuous operation, thereby maintaining measurement precision while enabling defect detection.
Solution Approach 2:
The system performs preliminary comparison and validation of the first timer's operation against the second timer before the key-on period begins or during transition periods. This preliminary action ensures that any potential defects or inaccuracies in the first timer are detected before they can cause erroneous diagnosis of vehicle parts, thereby maintaining measurement precision while enabling proactive defect detection.
Data Source
AI summary
Provided is an electronic control device including a timer that operates during a key-off time period, the electronic control device having high reliability to diagnose whether the timer is normally operated even during the key-off time period. The electronic control device includes a first power supply unit to which a battery voltage is always supplied as a power supply voltage, the first power supply unit including a first timer that measures a key-off time period, a diagnostic timer different from the first timer, and a first timer diagnosis unit that compares a timer value of the first timer with that of the diagnostic timer during the key-off time period.