Automatic Transmission Oil Temperature Sensor Offset Diagnosis
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Solution Overview
Problem
Existing abnormal state diagnosis methods for oil temperature sensors in automatic transmissions fail to detect offset abnormalities promptly and accurately, especially after engine restart, and are limited by requiring a predetermined time period for vehicle running and relying solely on sensor values without considering deviations from normal values.
Innovation Solution
The method involves a warm-up judgment step in the engine control module to assess engine side temperature sensors, a sensor normal operation judgment step to confirm temperature detection, a provisional judgment step in the automatic transmission control unit to compare sensor values within predetermined thresholds, and a final judgment step to determine abnormal states based on permission signals from the engine control module, enabling immediate detection of offset abnormalities post-engine restart without conditioning on vehicle running.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the abnormal state is judged only by using the oil temperature sensor value and waiting for a predetermined time period, then the judgment is simple to implement, but the offset abnormal state cannot be detected immediately after engine restart
Solution Approach 1:
The system performs preliminary warm-up judgment and sensor operation verification during the engine warm-up state before the actual abnormal state diagnosis. This preliminary action ensures that when the engine restarts, the comparison between engine side temperature sensor and oil temperature sensor can immediately detect offset abnormalities without waiting for a predetermined time period, thus resolving the contradiction between detection accuracy and time delay
Solution Approach 2:
The invention introduces the engine side temperature sensor as an intermediary reference to compare with the oil temperature sensor value. This intermediary enables the detection of offset abnormalities by providing a reliable reference temperature that reflects the actual thermal state, allowing immediate detection without time delay while maintaining high accuracy
2Measurement precision
If the judgment is performed only by the AT control unit after a predetermined time period of vehicle running, then the system structure is simple, but the offset abnormal state cannot be detected immediately after engine restart
Solution Approach 1:
The diagnosis function is segmented into two independent but coordinated parts: the engine control module performs warm-up judgment and sensor operation verification, while the AT control unit performs the abnormal state diagnosis by comparing temperature values. This segmentation allows each unit to perform its specific function independently, enabling immediate detection after restart while maintaining clear system architecture
Solution Approach 2:
The invention merges the warm-up judgment function and the abnormal state diagnosis function into a coordinated mutual diagnosis system. The engine control module's warm-up judgment result is combined with the AT control unit's temperature comparison to achieve immediate and accurate detection of offset abnormalities, resolving the contradiction between detection capability and system complexity
3Measurement precision
If the oil temperature sensor value is compared without considering deviation from normal value, then the judgment criterion is simple, but the offset abnormal state cannot be detected
Solution Approach 1:
The invention changes the judgment parameter from absolute temperature value comparison to deviation width comparison. By calculating the upper and lower deviation widths between the engine side temperature sensor value and the oil temperature sensor value, and comparing these deviations against predetermined thresholds, the system can accurately detect offset abnormalities while maintaining a clear and implementable judgment criterion
Data Source
AI summary
An abnormal state diagnosis method for an automatic transmission oil temperature sensor includes: a warm-up judging step of judging whether a sensor value from an engine side temperature sensor in an engine warm-up state indicates the engine warm-up state; a sensor normal operation judgment step of starting to judge whether the engine side temperature sensor including the warm-up judgment result normally performs a temperature detection operation; a provisional judgment step of judging whether an upper or lower deviation width between the sensor value of the engine side temperature sensor and an oil temperature sensor value from an automatic transmission oil temperature sensor is equal to or smaller than a predetermined threshold value; and a final judgment step of determining the judgment result by the provisional judgment step when the automatic transmission control unit receives a permission signal from the engine control module.