Automatic Transmission Shift Control for Accurate Clutch Engagement Detection
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Solution Overview
Problem
Existing shift control technologies for automatic transmissions face challenges in accurately detecting the engagement start time point due to wear and individual differences in friction elements, leading to inefficiencies in hydraulic control and potential shift quality issues.
Innovation Solution
A shift control device that includes an engagement control unit, a hydraulic pressure detecting unit, and an engagement start detecting unit, which calculates a predicted hydraulic pressure and detects the engagement start time point based on the difference between detected and reference pressures, improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hydraulic pressure is monitored using conventional methods (hydraulic switches or fixed timing), then the control system remains simple, but the detection accuracy of engagement start time point deteriorates due to wear and individual differences
Solution Approach 1:
The patent implements feedback by continuously monitoring the actual hydraulic pressure in the engagement hydraulic chamber and comparing it with a pre-stored reference pressure value that corresponds to the engagement start point. The control unit detects the engagement start time point based on this feedback comparison, thereby achieving accurate detection despite wear and individual differences in friction elements.
Solution Approach 2:
The patent stores reference pressure values that correspond to different engagement start time points in a map or table structure. By selecting and comparing against the appropriate reference value based on current operating conditions, the system adapts to varying parameters such as wear程度 and individual differences without changing the physical structure of the detection system.
2Speed
If friction elements are replaced during shifting to achieve quick engagement, then engagement speed improves, but the risk of blow-up phenomenon or pull-in feeling increases due to timing control difficulties
Solution Approach 1:
The control unit uses feedback from the hydraulic pressure sensor to detect the actual engagement start time point by comparing the monitored pressure with the reference pressure. This feedback mechanism enables precise timing control of friction element replacement, ensuring that the release side friction element is released and the engagement side friction element is engaged at the optimal moment, thereby preventing both blow-up phenomenon and pull-in feeling while maintaining quick engagement.
3Manufacturing precision
If individual differences and wear of friction elements are not accounted for, then the control system remains simple, but the accuracy of shift control deteriorates
Solution Approach 1:
The system employs feedback by storing reference pressure values that account for individual differences and wear characteristics of friction elements. The control unit compares the actual hydraulic pressure with these pre-stored reference values to detect the engagement start time point accurately, thereby compensating for variations without requiring complex adaptive learning algorithms or additional sensors.
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
Enhances the accuracy of shift control by precisely determining the engagement start time point, thereby improving the overall accuracy and efficiency of shift operations in automatic transmissions.
Implementation Method 1
an engagement hydraulic pressure supplied to an engagement hydraulic chamber of an engagement side friction element
Implementation Method 2
In the precharge process, an engagement hydraulic pressure supplied to an engagement hydraulic chamber of an engagement side friction element is controlled so as to rise quickly, thereby quickly filling the engagement hydraulic chamber with operating oil
Data Source
AI summary
A shift control device for an automatic transmission includes: an engagement control unit that controls an engagement hydraulic pressure supplied to an engagement hydraulic chamber of an engagement side friction element; a hydraulic pressure detecting unit that detects the engagement hydraulic pressure; a reference setting unit that calculates a predicted value of the engagement hydraulic pressure during shifting, based on a rising characteristic of the engagement hydraulic pressure from when supply of the engagement hydraulic pressure is started to when engagement of the engagement side friction element is started, and sets the predicted value as a reference hydraulic pressure; and an engagement start detecting unit that detects an engagement start time point of the engagement side friction element, based on a difference between the hydraulic pressure detected by the hydraulic pressure detecting unit during the shifting and the reference hydraulic pressure.