Temperature Sensor Diagnosis Device for Automatic Transmission
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Solution Overview
Problem
Existing diagnosis techniques for temperature sensor output voltage stuck malfunctions in automatic transmissions are prone to erroneous diagnoses due to balanced heat generation and cooling, leading to inaccurate detection of sensor malfunctions.
Innovation Solution
A diagnosis device that calculates output voltage estimation values for both hot and cold external air states and determines a malfunction only if the change in these values exceeds specific thresholds and the output voltage remains unchanged for a predetermined time, ensuring accurate detection of output voltage stuck malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output voltage stuck malfunction is determined based on accumulated running time and substantial unchanged output voltage, then the malfunction detection capability is improved, but erroneous diagnosis occurs when heat generation and cooling are balanced causing actual temperature to be substantially constant
Solution Approach 1:
The system pre-calculates and stores expected output voltage values corresponding to various vehicle operating conditions (speed, acceleration, gear position) before actual diagnosis occurs. During operation, these pre-calculated reference values are retrieved and compared against actual sensor readings, enabling rapid and accurate malfunction detection without requiring complex real-time thermal modeling.
Solution Approach 2:
The invention introduces an intermediary expected output voltage value that mediates between the complex thermal dynamics of the transmission system and the simple voltage reading from the temperature sensor. This expected value serves as a reference bridge, allowing the system to detect malfunctions by comparing actual voltage against what should be expected under current operating conditions, thereby avoiding false positives from temporary thermal equilibria.
2Speed
If the diagnosis system continuously monitors output voltage changes, then the response time for detecting malfunctions is improved, but the complexity of the diagnosis device increases
Solution Approach 1:
The system pre-calculates and stores expected output voltage values corresponding to various vehicle operating conditions (speed, acceleration, gear position) before actual diagnosis occurs. During operation, these pre-calculated reference values are retrieved and compared against actual sensor readings, enabling rapid and accurate malfunction detection without requiring complex real-time thermal modeling.
Solution Approach 2:
The diagnosis system utilizes existing vehicle operating data (speed, acceleration, gear position) that is already being collected for other control functions. By leveraging this existing information to calculate expected temperature sensor output, the system achieves comprehensive monitoring capability without adding separate sensors or complex dedicated diagnostic hardware.
Data Source
AI summary
A diagnosis device for a temperature sensor provided to a power transmission device transmits driving force generated by a driving power source of a vehicle. The diagnosis device includes: an output voltage estimating unit to calculate an output voltage estimation value of the temperature sensor, based on the operating state of the vehicle; and an output voltage stuck malfunction determining unit to determine an output voltage stuck malfunction of the temperature sensor, in a case where the amount of change of the output voltage estimation value is equal to or above a first threshold value, and the amount of change of output voltage of the temperature sensor is equal to or below a second threshold value.