Automatic Transmission Sensor Diagnosis With Staged Torque Limiting
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Solution Overview
Problem
Conventional automatic transmission temperature sensor diagnosis systems face challenges in detecting double failures between primary and secondary temperature sensors, leading to adverse effects on driving performance and transmission condition when a single sensor failure is diagnosed, as immediate countermeasures can affect driving performance or fail to detect subsequent double failures.
Innovation Solution
A redundant system with independent primary and secondary board temperature sensors, where the diagnosis controller performs torque limitation during a predetermined travel section after detecting a single failure and applies transmission shift restriction after the section ends to prepare for potential double failure, ensuring driving performance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission shift restriction is applied immediately after single sensor failure diagnosis, then transmission protection is improved, but driving performance deteriorates
Solution Approach 1:
The system applies torque limitation as a preliminary protective measure immediately after single sensor failure diagnosis, while delaying the more restrictive transmission shift restriction until after a predetermined travel section is completed. This preliminary action protects the transmission from potential double failure damage while minimizing impact on driving performance during the transition period.
2Productivity
If transmission shift restriction is suspended after single sensor failure diagnosis, then driving performance is maintained, but transmission safety deteriorates due to undetected double failure
Solution Approach 1:
The system introduces a predetermined travel section as an intermediary period between single sensor failure diagnosis and full transmission shift restriction. During this intermediate period, torque limitation is applied as a less intrusive protective measure, allowing the system to monitor for double failure while maintaining better driving performance than immediate full restriction would provide.
3Measurement precision
If redundant temperature sensors are implemented, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The redundant temperature sensor system performs self-diagnosis by comparing readings between the primary and secondary sensors. When a discrepancy exceeds a predetermined threshold, the system automatically diagnoses sensor abnormality and applies appropriate protective measures. This self-service capability improves temperature detection reliability while minimizing the need for additional complex diagnostic infrastructure.
Data Source
AI summary
A diagnosis device determines diagnoses one of primary and secondary board temperature sensors as abnormal, in response to a condition that a state in which a primary temperature sensor value and a secondary temperature sensor value deviate from each other by a predetermined value or more continues for a predetermined duration or more; performs torque limitation to limit a torque inputted from an engine to an automatic transmission, during driving in a predetermined travel section based on a predetermined condition, after the one of the primary and secondary board temperature sensors is diagnosed as abnormal; and performs transmission shift restriction to restrict shifting of the automatic transmission along with the torque limitation, in response to a condition that the one of the primary and secondary board temperature sensors continues to be diagnosed as still abnormal after the driving in the predetermined travel section is completed.