Hydraulic Torque Converter Thermal Management via Predictive Torque Control
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Solution Overview
Problem
The existing control systems for hydraulic torque converters in motor vehicles face challenges in maintaining maximum crossing force against resistance forces without overheating, especially in off-road conditions, due to unpredictable driving conditions and limitations in gear ratio, leading to potential breakdowns and loss of power transmission.
Innovation Solution
A method and system that determine the temperature gradient of the hydraulic torque converter oil, estimate the resistance force curve based on the vehicle's practical mass, and adjust engine torque in real-time to anticipate and manage thermal stress, avoiding overheating while maintaining maximum crossing force without additional sensors or actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the vehicle uses maximum decoupling level in hydraulic torque converter to get moving under off-road conditions, then the torque transmission capability is improved, but the oil temperature increases leading to power loss and component failure
Solution Approach 1:
The control system performs preliminary action by predicting future oil temperature based on current temperature and rate of change, and proactively limiting engine torque before the temperature reaches critical levels. This prevents thermal stress accumulation while maintaining torque transmission capability during off-road conditions.
Solution Approach 2:
The system implements feedback control by continuously monitoring oil temperature and its rate of change, then adjusting engine torque limits dynamically. The control module uses this feedback to maintain torque transmission while preventing oil overheating through real-time torque adjustment.
2Reliability
If the vehicle limits engine torque to prevent oil overheating, then the thermal stress on torque converter is reduced, but the vehicle loses off-road capability to climb slopes or cross difficult terrain
Solution Approach 1:
The system applies dynamics by making the engine torque limit dynamic rather than static. The torque limit adjusts continuously based on real-time oil temperature and its rate of change, allowing maximum torque during cool conditions and reducing torque only when thermal stress becomes problematic, thus maintaining off-road capability while protecting components.
Solution Approach 2:
The control system changes the parameter of engine torque limit based on thermal conditions. By modifying the torque parameter dynamically according to oil temperature and heating rate, the system maintains reliability while preserving off-road performance when thermal conditions permit.
3Temperature
If the vehicle is equipped with transmission reduction gears to reduce thermal stress, then the oil temperature is controlled within permissible limits, but the device complexity and cost increase
Solution Approach 1:
The system replaces the mechanical solution of additional gear reduction with an electronic control solution. By using engine torque limiting based on thermal prediction, the system achieves oil temperature control without adding mechanical complexity, maintaining simplicity while managing thermal stress.
4Temperature
If the existing control systems abruptly lower engine torque when overheating is detected, then the oil temperature is reduced, but the vehicle experiences sudden torque breaks and unpredictable behavior
Solution Approach 1:
The control system performs preliminary action by limiting torque before critical temperature is reached. By predicting temperature trends and acting in advance, the system avoids sudden torque reductions and maintains stable, predictable vehicle behavior while still protecting against overheating.
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 allows for continuous and predictable vehicle behavior, anticipating critical situations and preventing abrupt torque breaks, while maintaining thermal resistance and crossing capacity without degrading transmission components, even in high-resistance areas like steep slopes or sandy terrain.
Implementation Method 1
A torque converter is a type of hydraulic coupling used to transmit power from a drive shaft to a rotating load
Implementation Method 2
A hydraulic torque converter also allows for gear reduction, meaning it increases torque when the input and output rotational speeds differ
Implementation Method 3
a pump, a stator and a turbine mounted in a common housing in which the oil transmits the torque and circulates in a closed circuit
Implementation Method 4
the power balance explicitly shows that the oil shear results in a power dissipation equal to the difference between the power supplied by the engine
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A system for controlling (20) a power train of a motor vehicle, the power train (20) being capable of delivering an engine torque to a hydraulic torque converter (13). The control system comprises means (21) for determining a temperature gradient of the oil of the hydraulic torque converter (13), means (22) for estimating a curve of the force of resistance to forward travel of the motor vehicle depending on a practical mass of the motor vehicle based on said temperature gradient, and means (23) for controlling said engine torque depending on said estimation.