Engine Heater Use Detection for Temperature Sensor Fault Diagnosis
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Solution Overview
Problem
Internal combustion engine heaters can cause incorrect fault diagnosis in temperature sensors when used during vehicle shutdown, leading to inaccurate temperature comparisons and potential engine reliability issues due to excessive heat generation.
Innovation Solution
A diagnostic system with a temperature derivative module and a heater use module that determines the derivative of engine fluid or component temperatures after startup, selectively indicating if an engine heater was used before vehicle startup based on the derivative, thereby distinguishing between heater use and sensor faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature sensors are used to monitor engine temperature for reliability, then engine reliability can be maintained, but heater use during shutdown causes incorrect fault diagnosis in temperature sensors
Solution Approach 1:
The system performs preliminary detection of heater use status before conducting temperature sensor fault diagnosis. By checking whether the heater was activated during the shutdown period prior to startup, the system can preemptively adjust its diagnosis logic to avoid false positives, ensuring accurate measurement assessment before reliability evaluation begins
Solution Approach 2:
The diagnostic system dynamically adjusts its fault detection criteria based on the operational history of the heater. Rather than using fixed threshold comparisons, the system adapts its temperature evaluation parameters according to whether heater use is detected, allowing the measurement precision to vary appropriately with system state while maintaining overall reliability
2Reliability
If engine heaters are used during shutdown to prevent excessive heat generation, then engine reliability is improved, but incorrect fault diagnosis occurs in temperature sensors
Solution Approach 1:
The system implements feedback by continuously monitoring heater operational status and using this information to adjust temperature sensor evaluation. The heater use detection creates a feedback loop where the system learns from past heater operation and adjusts its interpretation of temperature data accordingly, preventing loss of accurate temperature information while maintaining reliability benefits
Solution Approach 2:
The heater use detection mechanism acts as an intermediary between the heater system and the temperature sensor diagnostic system. This intermediary layer processes heater status information and translates it into appropriate diagnostic adjustments, preventing direct conflict between heater operation and temperature measurement accuracy
3Device complexity
If simple temperature comparison methods are used for fault diagnosis, then device complexity is reduced, but accuracy of fault detection decreases when heater use is involved
Solution Approach 1:
The diagnostic system is segmented into distinct functional modules: a heater use detection module that separately identifies heater operational status, and a temperature evaluation module that uses this information to adjust its fault detection logic. This segmentation allows each module to remain relatively simple while the combination achieves high accuracy by handling heater-related cases separately from normal operation cases
Data Source
AI summary
A diagnostic system includes a temperature derivative module and a heater use module. The temperature derivative module determines a derivative of a temperature of one of a fluid of an engine of a vehicle and a component of the engine measured by a temperature sensor after a vehicle startup event. The heater use module selectively indicates that an engine heater was used before the vehicle startup event based on the derivative.