Automatic Transmission Lubricant Control to Prevent Shift Shock
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Solution Overview
Problem
Existing automatic transmission systems face challenges in controlling lubricant supply to friction engagement elements during gear changes, leading to increased stirring resistance, drag, and gear change shocks due to varying thermal loads and lubricant viscosity, which affect durability and engagement timing.
Innovation Solution
A control device with a processor that executes gear change control logic and lubricant supply control logic to independently manage lubricant supply to friction engagement elements based on vehicle operating states, ensuring non-overlapping operations to prevent friction coefficient changes and minimize gear change shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricant supply amount is increased to cool friction plates during gear change, then durability is improved, but stirring resistance and drag increase during disengagement
Solution Approach 1:
The lubricant supply amount is dynamically adjusted based on the operational state of the friction engagement element. During engagement, full lubricant supply is provided to cool the friction plates and ensure durability. During disengagement, lubricant supply is reduced or stopped to minimize stirring resistance and energy loss. This dynamic control is achieved through a lubricant supply control valve that responds to control signals from the control device.
Solution Approach 2:
The supply amount parameter of lubricant is changed according to the operational phase of the friction engagement element. The control device switches between different lubricant supply rates (high supply during engagement, low or zero supply during disengagement) based on detected operational states, thereby optimizing both durability and energy efficiency.
2Reliability
If lubricant supply amount is switched based on thermal load, then durability is secured, but gear change shock occurs when switching and gear change operations overlap
Solution Approach 1:
The control device detects the start of gear change operation in advance and preemptively prevents lubricant supply amount switching during this period. By identifying the gear change timing through detection of hydraulic pressure changes or control signals, the system ensures that lubricant supply remains stable throughout the gear change process, avoiding friction coefficient variations that would cause engagement timing deviation and gear change shock.
Solution Approach 2:
The control device acts as an intermediary between the lubricant supply control valve and the gear change control system. It receives information about gear change operations and transmits appropriate control signals to the lubricant supply control valve, coordinating the timing of lubricant supply adjustments with gear change operations to prevent harmful overlaps.
3Loss of energy
If lubricant supply is limited during low thermal load, then stirring resistance is suppressed, but friction plates overheat during high thermal load
Solution Approach 1:
The lubricant supply system operates dynamically with two distinct modes: during engagement, high lubricant supply is provided to cool friction plates even when thermal load is low, preventing overheating. During disengagement, lubricant supply is minimized to reduce stirring resistance. The control device switches between these modes based on the engagement state and thermal load conditions.
Solution Approach 2:
Different lubricant supply strategies are applied to different operational phases of the friction engagement element. During engagement, the friction plates receive abundant lubricant for cooling. During disengagement, the lubricant supply is reduced. This localized quality adjustment ensures optimal performance for each operational phase without compromising overall system efficiency.
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 effectively suppresses stirring resistance and drag while maintaining durability by optimizing lubricant supply according to vehicle conditions, preventing gear change shocks and ensuring precise engagement timing.
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
AI summary
A control device for an automatic transmission is provided, which includes a friction engagement element, and a processor configured to execute gear change control logic configured to control a gear change operation by supplying and discharging hydraulic fluid for forming a gear stage to/from the friction engagement element, and lubricant supply control logic 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 processor controls the gear change operation and the switching operation to not overlap with one another.