Shift Range Control with Temperature-Gated Valley Position Learning
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Solution Overview
Problem
In low-temperature environments, the viscosity of working fluid in automatic transmissions increases, causing the locking portion to be less prone to fall to the valley bottom of recesses, leading to erroneous learning of the valley position and subsequent incorrect shifting range switching and degradation in rotationally positioning the rotation member.
Innovation Solution
A shift range control device that includes an angle acquisition unit, a valley position learning unit, a temperature acquisition unit, a learning permission unit, a drive voltage-current correction unit, and a rotation number correction unit, which permits valley position learning only when the environmental temperature is higher than a predetermined value, and adjusts drive voltage or rotation number to ensure accurate learning by preventing learning in low-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If valley position learning is performed in low-temperature environments, then the system attempts to learn the valley position, but the learning accuracy deteriorates due to increased working fluid viscosity preventing the locking portion from falling to the valley bottom
Solution Approach 1:
The control device prevents valley position learning from being executed when the ambient temperature is below the predetermined threshold. By blocking the learning operation before it starts in low-temperature conditions, the system avoids the harmful effect of high viscosity preventing the locking portion from reaching the valley bottom, thereby maintaining learning accuracy.
Solution Approach 2:
The system changes the operational parameter (learning permission) based on temperature conditions. When temperature drops below the threshold, the learning function is disabled, effectively adapting the system's behavior to environmental conditions to prevent accuracy degradation caused by viscosity changes.
2Stability of the object's composition
If the locking portion is prevented from falling to the valley bottom due to high viscosity, then the rotation member positioning deteriorates, but allowing learning in these conditions would improve operational continuity
Solution Approach 1:
The system preemptively prevents valley position learning execution in low-temperature environments before positioning accuracy can deteriorate. This approach prioritizes positioning stability over operational continuity, accepting a temporary inability to learn rather than risking inaccurate positioning.
Solution Approach 2:
The system accepts that learning operations may need to be postponed or repeated later when conditions improve, rather than forcing a potentially failed learning attempt. This approach treats individual learning attempts as disposable operations that can be retried under better conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the accuracy of valley position learning by preventing erroneous learning in low-temperature environments, ensuring precise shifting range switching and maintaining the rotation member's correct positioning.
Implementation Method 1
a temperature acquisition unit that may acquire an environmental temperature
Data Source
AI summary
A shift range control device for a shift range switching mechanism that is rotatably coupled with a shift actuator and includes a rotation member having multiple recesses and a locking portion rotationally positioning the rotation member by being locked to one of the multiple recesses, controls a motor of the shift actuator to switch a shift range. The shift range control device includes: an angle acquisition unit that acquires a rotation angle of an output shaft of the shift actuator; a valley position learning unit that performs valley position learning for learning, as a valley position, the rotation angle of the output shaft; and a temperature acquisition unit that acquires an environmental temperature.