Torque Converter Lockup Clutch Slip Control During Coasting
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Solution Overview
Problem
Conventional torque converters with lockup clutches face challenges in optimizing fuel economy during coasting conditions, as the engagement and disengagement of the lockup clutch can lead to inefficient energy transfer and increased fuel consumption, particularly when the vehicle is traveling downhill or in idle operations.
Innovation Solution
A vehicle control module is used to detect coasting conditions and selectively engage or disengage the lockup clutch to maintain the rotational speed of the drive unit above a reference threshold, employing partial engagement to control slip between the pump and turbine, thereby reducing fuel consumption and extending coasting distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lockup clutch is engaged during coasting conditions, then mechanical coupling between drive unit and transmission is achieved, but fuel consumption increases and energy transfer efficiency decreases
Solution Approach 1:
The lockup clutch engagement state is dynamically adjusted based on vehicle operating conditions. The controller monitors coasting conditions and selectively engages or disengages the lockup clutch to optimize the balance between mechanical coupling reliability and fuel consumption, transitioning from a static engagement approach to a dynamic control strategy.
Solution Approach 2:
The system changes the engagement parameter of the lockup clutch based on detected operating conditions. During coasting conditions, the clutch engagement torque is reduced or disengaged entirely, while during normal operation it remains engaged, allowing the system to adapt the mechanical coupling parameter to minimize fuel consumption while maintaining reliability when needed.
2Use of energy by moving object
If the lockup clutch is disengaged during coasting conditions, then fuel consumption is reduced, but drive unit stalling risk increases
Solution Approach 1:
The control system continuously monitors vehicle operating parameters including vehicle speed, engine RPM, and load conditions. Based on this feedback, the controller determines whether coasting conditions exist and adjusts lockup clutch engagement accordingly, disengaging during sustained coasting to save fuel while maintaining engagement during conditions that could lead to stalling, thus resolving the contradiction between fuel economy and stability.
Solution Approach 2:
The system detects coasting conditions in advance and proactively adjusts lockup clutch engagement before stalling risk becomes critical. By monitoring trends in vehicle speed and engine load, the controller can disengage the clutch during beneficial coasting periods while maintaining engagement when approaching stalling thresholds, preventing the contradiction from manifesting.
3Device complexity
If conventional lockup clutch control is used, then simple control logic is maintained, but coasting distance is limited due to inefficient energy transfer
Solution Approach 1:
The controller uses feedback from vehicle speed sensors and engine parameters to detect coasting conditions and selectively control lockup clutch engagement. This feedback-based control extends coasting distance by maintaining momentum during downhill or idle coasting while preserving the relatively simple overall control architecture, thus improving productivity without excessive complexity.
Solution Approach 2:
The system dynamically adjusts lockup clutch engagement based on real-time detection of coasting conditions, transitioning from static to dynamic control. This allows the vehicle to maximize coasting distance during appropriate conditions while maintaining adequate control logic complexity only where needed, achieving extended productivity with minimal added system complexity.
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 enhances fuel economy by minimizing fuel consumption during idle operations and reducing the likelihood of drive unit stalling, while maintaining efficient energy transfer, thus promoting longer coasting distances and reducing the demand for additional power.
Implementation Method 1
a lockup clutch that is engageable to mechanically couple the drive unit to the transmission
Implementation Method 2
a pump that is driven by the drive unit, a turbine that is fluidly coupled to the pump
Data Source
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AI summary
A method and system are provided for operating a lockup clutch of a torque converter (116) of a motor vehicle. The torque converter includes a pump (134) rotatably driven by a drive unit (112), a rotatable turbine (136) fluidly coupled to the pump and configured to drive an input shaft of a transmission (114), and a lockup clutch (140) selectively engageable to non-fluidically couple the pump to the turbine to transmit torque from the drive unit to the transmission. The operation of the lockup clutch is controlled by the system in response to detecting that the motor vehicle is coasting.