Torque Converter Stall Temperature Control via Slip Speed Torque Limiting
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Solution Overview
Problem
Conventional torque converters face challenges in controlling operating temperature during torque converter stall conditions, where the turbine rotational speed is at or near zero, and the pump rotational speed is above a threshold, leading to potential excessive heat generation.
Innovation Solution
A method and system that determine whether a torque converter is in a stall condition, calculate the slip speed, and adjust the engine output torque limit based on desired slip speeds to control the operating temperature, involving sensors for rotational speed monitoring and control circuits to manage engine output torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the pump rotational speed is maintained above threshold during stall conditions, then the torque converter can generate sufficient torque multiplication, but excessive heat is generated due to high slip speed between pump and turbine
Solution Approach 1:
The control system dynamically adjusts engine output torque limits based on real-time monitoring of pump and turbine rotational speeds to maintain slip speed within a desired range. By changing the torque parameter as a function of speed differential, the system achieves torque multiplication while preventing excessive heat generation during stall conditions
Solution Approach 2:
The system continuously monitors rotational speeds of both pump and turbine, calculates actual slip speed, and uses this feedback to determine appropriate engine output torque limits. This closed-loop control ensures that torque multiplication is maintained when needed while automatically reducing torque to prevent overheating when slip speed becomes excessive
2Temperature
If engine output torque is limited to control temperature, then excessive heat buildup is prevented, but torque multiplication capability is reduced
Solution Approach 1:
The engine output torque limit is not fixed but dynamically adjusted based on real-time operating conditions, specifically the slip speed between pump and turbine. The system transitions between different torque limit states (first and second engine output torque limits) depending on whether actual slip speed exceeds desired slip speed, allowing optimal balance between temperature control and torque multiplication
3Temperature
If slip speed is reduced to minimize heat generation, then operating temperature is controlled, but the ability to maintain torque multiplication during stall is compromised
Solution Approach 1:
The control system establishes desired slip speed thresholds in advance and uses these pre-defined parameters to guide real-time torque limiting decisions. By having predetermined performance characteristics and slip speed targets, the system can quickly respond to changing conditions while maintaining reliable torque multiplication without excessive heat generation
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
Effectively limits engine output torque to prevent excessive heat buildup during torque converter stall conditions, ensuring safe and efficient operation by monitoring and adjusting torque limits based on slip speed and temperature thresholds.
Implementation Method 1
a pump that is driven by the prime mover and fluidly coupled to a turbine that is connected to the transmission
Implementation Method 2
controlling the operating temperature of a torque converter during torque converter stall conditions... in which the rotational speed of the turbine is at or near zero and the rotational speed of the pump is above a threshold pump speed
Data Source
AI summary
A method and system are provided for controlling the operating temperature of a torque converter during torque converter stall conditions. The torque converter has a pump rotatably driven by an internal combustion engine and a rotatable turbine fluidly coupled to the pump. The system first determines whether the torque converter is currently in a torque converter stall condition, and, if so, determines a slip speed as a difference in rotational speeds between the pump and the turbine, determines an engine output torque limit as a function of the slip speed and a desired slip speed, and controls the operating temperature of the torque converter by limiting output torque produced by the engine based on the engine output torque limit.