Automatic Transmission Lubricant Control for Smooth Gear Shifts
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Solution Overview
Problem
Existing automatic transmission systems face issues with gear change shocks due to variations in lubricant supply during gear changes, leading to suboptimal engagement timing and reduced durability of friction engagement elements.
Innovation Solution
A control device that adjusts lubricant supply to friction engagement elements based on vehicle operating state, preventing overlap between gear change and lubricant supply switching operations to maintain consistent friction coefficient and prevent premature engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricant supply amount is increased to cool friction engagement elements during high thermal load, then durability is improved, but stirring resistance and drag increase causing gear change shock
Solution Approach 1:
The lubricant supply amount is dynamically adjusted based on the operating state of the friction engagement element. The control device increases lubricant supply when thermal load is high to cool the friction plates, and reduces supply when thermal load is low to minimize drag and stirring resistance, thereby preventing gear change shock while maintaining durability
Solution Approach 2:
The supply amount of lubricant is changed as a controllable parameter based on thermal load conditions. By monitoring the operating state and adjusting the lubricant flow rate accordingly, the system optimizes the balance between cooling effectiveness and minimization of harmful drag effects during gear changes
2Temperature
If lubricant supply is switched based on thermal load, then cooling effectiveness is improved, but supply amount varies during gear change causing engagement timing deviation
Solution Approach 1:
The control device detects a gear change command in advance and prohibits lubricant supply switching during the gear change period. This preliminary action ensures that the lubricant supply amount remains stable throughout the gear change process, preventing any variation that could cause engagement timing deviation, while still allowing thermal load-based switching during normal operation
Solution Approach 2:
The control device acts as an intermediary between the thermal load monitoring system and the lubricant supply system. It mediates by blocking supply switching commands during gear change periods, thus protecting the precision of engagement timing while maintaining the ability to switch supply based on thermal load during stable operation
3Loss of energy
If lubricant supply is limited during low thermal load, then stirring resistance is reduced, but friction plates may overheat during high thermal load
Solution Approach 1:
The lubricant supply system operates dynamically with two modes: limited supply during low thermal load to minimize stirring resistance and energy loss, and increased supply during high thermal load to effectively cool the friction plates. The control device continuously monitors thermal load and switches between these modes accordingly
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 ensures smooth gear changes by maintaining optimal engagement timing and enhancing the durability of friction engagement elements by controlling lubricant supply according to vehicle conditions, thereby reducing gear change shocks and ensuring reliable operation.
Implementation Method 1
supplying lubricant to the friction engagement elements to cool the friction plates
Implementation Method 2
supplying lubricant to the friction engagement elements
Data Source
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AI summary
A control device for an automatic transmission is provided, which includes a friction engagement element, and a control unit configured to control a gear change operation by supplying and/or discharging hydraulic fluid for forming a gear stage to/from the friction engagement element, and configured to control to switching operation of a supply amount of lubricant to the friction engagement element according to an operating state of a vehicle. The control unit controls the gear change operation and the switching operation to not overlap with one another.