Automatic Transmission Control System Shift Shock Suppression
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Solution Overview
Problem
Existing automatic transmission control systems experience shift shocks due to erroneous learning corrections when the torque converter's speed ratio is lower than desired, leading to increased torque and inadequate engine rotation speed variations.
Innovation Solution
A control system that measures actual time lag and adjusts the time lag map based on engine torque and vehicle operation conditions, incorporating a learning correction mechanism to stabilize hydraulic pressure instructions and minimize shift shocks, with additional features for eco-shift modes that adjust time lag maps according to turbine rotation speed and engine rotation speed increasing rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If learning correction is performed using a fixed time lag map based on engine torque data, then the control system can suppress shift shock under normal operating conditions, but erroneous learning occurs when the torque converter speed ratio is smaller than desired, leading to increased torque and reduced engine rotation speed variability
Solution Approach 1:
The time lag map is made dynamic by correcting reference time lag values based on detected engine rotation speed and turbine rotation speed. Instead of using a fixed time lag map based solely on engine torque data, the system adjusts the reference time lag according to the actual operating conditions, particularly the engine rotation speed and turbine rotation speed, to account for torque converter effects and prevent erroneous learning.
Solution Approach 2:
The system incorporates feedback mechanisms by detecting actual engine rotation speed and turbine rotation speed, then using this information to correct the reference time lag values in the time lag map. This feedback loop allows the system to adapt to varying torque converter conditions and maintain accurate time lag measurements across different operating scenarios.
2Power
If the torque converter operates at lower speed ratios, then torque capacity increases, but engine rotation speed variability decreases causing larger actual time lag that leads to erroneous learning
Solution Approach 1:
The system changes parameters by adjusting the reference time lag values based on detected engine rotation speed and turbine rotation speed. When the torque converter operates at lower speed ratios with higher torque capacity, the system detects the reduced engine rotation speed variability and compensates by modifying the reference time lag to reflect the actual operating conditions, preventing erroneous learning.
3Device complexity
If a common shift map is used for all operating conditions, then the control system is simple to implement, but it cannot account for torque converter effects under different speed ratio conditions
Solution Approach 1:
While maintaining a relatively simple control structure, the system introduces dynamic correction to the time lag map by incorporating detected engine rotation speed and turbine rotation speed. This allows the system to adapt to different operating conditions without requiring completely separate control maps for each scenario, balancing simplicity with reliability.
Data Source
AI summary
A control system for controlling an automatic transmission that is capable of establishing a given speed stage by engaging a given frictional element. The control system comprises an actual time lag measuring section that measures an actual time lag from the time when a speed change instruction for the given speed stage is issued to the time when a gear ratio of the automatic transmission starts to change for the purpose of establishing the given speed stage, a torque detecting section that detects a torque from an engine, a time lag map that provides a suitable time lag in accordance with the detected torque from the engine, a learning correction section that corrects, by learning control, an instruction value for the hydraulic pressure led to the frictional element in a manner to cause the actual time lag to have the same value as the suitable time lag; and a time lag map correcting section that corrects the suitable time lag in accordance with an operation condition of an associated motor vehicle.