Automatic Transmission Control Device for Friction Element Heat Protection
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Solution Overview
Problem
Existing automatic transmission control systems inadequately manage heat generation in frictional engagement elements during speed changes, leading to potential burnout and inefficient driving force delivery, as they either rely on timer-based delays that are not condition-specific or fail to consider heat generation during downshifts.
Innovation Solution
A control device that includes a speed change controller, temperature calculator, rotation difference calculator, and determining unit to assess the engageability of frictional engagement elements based on temperature and rotation difference, delaying engagement until safe conditions are met to prevent heat damage and optimize driving force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upshift timing is delayed by a predetermined time to cool the frictional engagement element, then the frictional engagement element can be protected from heat damage, but the driving force provided to the driver becomes insufficient due to response delay
Solution Approach 1:
The patent applies dynamics by making the delay time variable rather than fixed. The control device dynamically adjusts the delay time based on real-time temperature conditions of the frictional engagement element, allowing the system to optimize between protection and response speed depending on the actual thermal state. This resolves the contradiction by adapting the delay duration to current operating conditions rather than applying a uniform predetermined delay.
Solution Approach 2:
The patent changes the parameter of delay time from a constant predetermined value to a variable parameter that depends on temperature conditions. By calculating the actual temperature of the frictional engagement element and adjusting the delay time accordingly, the system modifies this critical parameter to balance heat protection needs with driving performance requirements.
2Device complexity
If the temperature of the frictional engagement element is calculated only during speed change, then the control is simpler, but heat generation during in-gear with high load is not considered leading to insufficient protection
Solution Approach 1:
The patent makes the temperature calculation function universal by applying it to all operating conditions where heat generation occurs, not just during speed change. The control device calculates temperature during both speed change operations and in-gear high-load conditions, ensuring comprehensive protection coverage across all scenarios that generate significant heat in the frictional engagement element.
3Reliability
If a timer operation time is set under the most severe condition to reliably protect the frictional engagement element, then protection is ensured, but the regulation time becomes excessively long causing insufficient driving force
Solution Approach 1:
The patent changes the regulation time parameter from a fixed conservative value based on worst-case conditions to a dynamic parameter calculated based on actual temperature conditions. By using real-time temperature data to determine the appropriate delay time, the system avoids the excessive regulation time that would result from always using the most severe condition timing, while still ensuring reliable protection when needed.
4Reliability
If the upshift timing is uniformly delayed at the temperature of a predetermined threshold or higher, then the frictional engagement element is protected, but the control is rough and driving force is insufficient
Solution Approach 1:
The patent applies dynamics by replacing uniform delayed control with dynamic, condition-specific control. Instead of applying a fixed delay whenever temperature exceeds a threshold, the system dynamically calculates the appropriate delay time based on the actual temperature and operating conditions, resulting in smoother and more precise control that maintains protection while improving driving comfort.
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
This solution effectively protects frictional engagement elements from heat damage by dynamically adjusting engagement timing according to real-time temperature and rotation differences, ensuring efficient driving force delivery and reducing the need for excessive regulation or timing delays.
Implementation Method 1
a heat quantity of heat that is generated during the engagement operation of the frictional engagement element used for the speed change tends to be increased
Implementation Method 2
the frictional engagement element whose temperature is at a high temperature due to the heat generated during the speed change operation is cooled to a temperature equivalent to automatic transmission fluid (ATF) of the automatic transmission mainly through heat exchange with the ATF
Data Source
AI summary
A control device for an automatic transmission includes a speed change controller configured to generate a speed change instruction. A temperature calculator is configured to calculate a temperature of at least one frictional engagement element among frictional engagement elements. A rotation difference calculator is configured to calculate a rotation difference between an input and an output of the at least one frictional engagement element. A determining unit is configured to determine whether the frictional engagement element is engageable or non-engageable based on the temperature and the rotation difference of the frictional engagement element and a pattern of the speed change instruction. The delay unit is configured to delay engagement until the determining unit determines that the frictional engagement element is engageable, if the determining unit determines that the frictional engagement element is non-engageable when the speed change controller generates the speed change instruction.