Automated Gearbox Thermal Protection for Overheat-Limited Launch
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Solution Overview
Problem
Current thermal protection methods for motor vehicle gearboxes rely on driver intervention, which is often ineffective, and require oversized cooling systems, increasing costs and mass, while failing to prevent critical temperature rises that degrade lubrication and mechanical components.
Innovation Solution
A controlled thermal protection method that automatically activates reduction in engine speed and torque setpoints, inhibits creeping driving modes, and modifies gear shift strategies when temperature thresholds are exceeded, with alerts to the driver only when necessary, to prevent temperature rises without increasing cooling system dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If driver warning and manual intervention are used for thermal protection, then driver awareness is improved, but protection effectiveness deteriorates because drivers rarely modify their behavior
Solution Approach 1:
The control unit automatically monitors temperature and executes protection measures without requiring driver intervention. The system serves itself by detecting temperature thresholds and autonomously adjusting engine torque, gear ratios, and cooling system operation, eliminating reliance on driver behavior modification while ensuring reliable thermal protection
Solution Approach 2:
The control unit continuously monitors temperature sensors and uses this feedback to automatically adjust protection measures. When temperature exceeds thresholds, the system receives feedback and autonomously modifies engine torque setpoints, gear shift timing, and cooling fluid flow, creating a closed-loop control system that ensures effective thermal protection without driver involvement
2Reliability
If cooling system dimensioning is increased to prevent temperature rise, then thermal protection is improved, but equipment cost and powertrain mass increase
Solution Approach 1:
The cooling system operates dynamically with variable capacity rather than being continuously oversized. The control unit adjusts cooling fluid flow rate and pump operation based on real-time temperature conditions, enabling a compact cooling system to provide adequate thermal protection only when needed, thereby reducing overall system mass while maintaining protection capability
Solution Approach 2:
The system changes operational parameters (cooling fluid flow rate, pump speed, valve positions) based on temperature conditions rather than maintaining fixed high-capacity settings. This allows a smaller cooling system to achieve the same thermal protection effect by operating at higher capacity only when temperature thresholds are exceeded, reducing equipment mass and cost
3Reliability
If engine torque setpoints are reduced to lower temperature, then thermal protection is improved, but vehicle acceleration performance deteriorates
Solution Approach 1:
The control unit applies torque reduction periodically or intermittently based on temperature thresholds rather than continuously. When temperature exceeds thresholds, torque setpoints are reduced; when temperature returns to normal ranges, full torque is restored. This periodic adjustment provides thermal protection while minimizing impact on acceleration performance during normal operating conditions
Solution Approach 2:
The system applies partial torque reduction only to the extent necessary to control temperature, rather than continuously reducing torque to low levels. The control unit calculates the minimum torque reduction needed to bring temperature back within thresholds, allowing the engine to deliver near-full torque during normal operation while providing sufficient thermal protection when needed
Data Source
Figure 1~2
AI summary
The invention concerns a method for thermal protection for a controlled gearbox of a motor vehicle powertrain, comprising: in the event of detection by a control unit of an estimated temperature exceeding a first protection threshold (STp1), the activating of a first protection mode (22) in which at least the speed and torque setpoints of the heat engine have reduced values according to a first reduction coefficient for the execution of a start-up phase of the vehicle; and, in the event of detecting an estimated temperature exceeding a second protection threshold (STp2), the activating of a second protection mode (23) comprising at least one inhibition command (23) inhibiting a driving mode, termed the crawling driving mode, for executing a start-up phase. The invention is suitable for motor vehicles.