Automatic Transmission Select Operation Determination
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Solution Overview
Problem
Existing automatic transmission systems face challenges in accurately determining select operations, particularly from the parking range to the drive range, leading to potential shocks and decreased start responsiveness due to incorrect engagement delay controls.
Innovation Solution
The system employs a combination of time measurement and input rotation speed detection to differentiate between select operations from the reverse range to the drive range and from the parking or neutral range to the drive range, using a moving inhibitor switch and hydraulic pressure indicators to determine the correct engagement sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engagement of the forward frictional engagement element is delayed to avoid transmission interlocking and shock, then the transmission interlocking is avoided, but the start responsiveness of the vehicle deteriorates due to select lag
Solution Approach 1:
The patent changes the parameter of engagement timing based on the detected select operation type. When a select operation from parking range or neutral range to drive range is detected, the engagement timing of the forward frictional engagement element is advanced (not delayed). When a select operation from reverse range to drive range is detected, the engagement timing is delayed. This parameter change based on operational context resolves the contradiction by avoiding unnecessary delays that cause select lag while still preventing transmission interlocking when needed.
2Device complexity
If the select operation determination is based solely on switch ON/OFF states, then the determination process is simple, but the determination accuracy deteriorates leading to erroneous operation identification
Solution Approach 1:
The patent introduces feedback mechanisms including a timer that measures the duration of the select operation and a rotation speed detector that provides feedback on input rotation speed. These feedback elements allow the control unit to accurately distinguish between different select operations (parking/neutral to drive vs. reverse to drive) by analyzing the temporal and rotational characteristics of the operation, thereby improving determination accuracy without excessive complexity.
Solution Approach 2:
The patent adds temporal dimension (operation duration measured by timer) and rotational speed dimension (input rotation speed detected by rotation speed detector) to the select operation determination process. By considering these additional dimensions beyond simple switch ON/OFF states, the system can accurately differentiate between similar select operations and avoid erroneous determination.
Data Source
AI summary
A transmission controller determines that a select operation has been performed from a reverse range to a drive range if a time during which a range other than the drive range has been selected is longer than a predetermined time threshold value and an input rotation speed of a transmission is lower than a predetermined rotation speed threshold value and determines that the select operation has been performed from a parking range or a neutral range to the drive range if the time during which the range other than the drive range has been selected is shorter than the time threshold value or the input rotation speed is higher than the rotation speed threshold value when the select operation has been performed from the range other than the drive range to the drive range during vehicle stop.