Automatic Transmission Static Disengagement via Turbine Torque
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Solution Overview
Problem
Existing automatic transmission systems with static disengagement functions based on engine speed require specific engine speed limiting values tailored to hydrodynamic characteristics, leading to high application effort and expense.
Innovation Solution
Implementing static disengagement in automatic transmissions based on a characteristic parameter of the turbine, such as turbine torque or speed, rather than engine speed, allowing for reduced application effort and improved fuel efficiency by shifting to neutral or parking positions or engaging clutches in slipping operation when vehicle speed is low and turbine parameters are below limiting values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static disengagement is implemented as a function of engine speed, then static disengagement can be achieved, but specific engine speed limiting values have to be established for each automatic transmission depending on hydrodynamic characteristics and idle speed, leading to high application effort and expense
Solution Approach 1:
The patent changes the control parameter from engine speed to turbine speed. This parameter change eliminates the need for transmission-specific calibration because the turbine speed directly reflects the hydrodynamic state of the torque converter, making the static disengagement function universally applicable across different transmissions without requiring establishment of specific limiting values for each application.
2Use of energy by moving object
If static disengagement is implemented based on engine speed, then the function can be activated, but the time fraction of vehicle stops with disengagement active is limited, reducing fuel efficiency
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring turbine speed and using it as the primary criterion for activating static disengagement. Since turbine speed directly indicates whether the vehicle is truly stopped or coasting, this feedback enables the system to maintain disengagement for the maximum appropriate duration during stops, thereby maximizing fuel efficiency without compromising drivability.
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 approach reduces application effort and fuel consumption by enabling more efficient static disengagement, particularly during vehicle stops, by using turbine parameters to determine when to disengage, thereby optimizing energy management and reducing the time fraction of stops with disengagement active.
Implementation Method 1
The automatic transmission comprises a hydrodynamical starting element, in particular a torque converter, such that the automatic transmission is connected to the engine of the motor vehicle by way of the hydrodynamical starting element. The hydrodynamical starting element comprises a pump on the engine side and a turbine on the transmission side.
Data Source
AI summary
A method for controlling an automatic transmission of a motor vehicle, namely for controlling a static disengagement function, such that if the motor vehicle's speed is lower than a limiting speed value and if, at the same time, at least one further initiation criterion is fulfilled, static disengagement is implemented. As a further initiation criterion, it is checked whether a characteristic parameter of a hydrodynamical starting element, in particular a torque converter, is below a limiting value of the characteristic parameter.