Engine Torque Limitation for Four-Wheel-Drive Thermal Management
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Solution Overview
Problem
Four-wheel drive vehicles face challenges with high fuel consumption and poor on-road performance due to difficulties in controlling engine torque, leading to front axle slipping and premature engagement of two-wheel drive mode, which reduces traction and control for drivers, especially in varying off-road conditions.
Innovation Solution
A system and method for controlling engine torque transfer in four-wheel drive vehicles, utilizing an actuator and calculation means to limit engine torque based on driving conditions and 4x4 system state, with mechanisms for immediate or gradual deactivation to maintain traction and control, including filtering and setpoint generation modules to manage torque variations and temperature-dependent performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the engine torque is increased to improve traction and off-road performance, then the crossing capability is improved, but the front axle begins to slip and the 4x4 device overheats, causing the system to switch to 4x2 mode
Solution Approach 1:
The system applies preliminary anti-action by proactively limiting engine torque before the 4x4 device overheats. The control module monitors temperature and torque levels, and reduces torque output in advance to prevent thermal overload and subsequent system failure, thereby maintaining 4x4 availability throughout the off-road sequence
Solution Approach 2:
The system changes the torque parameter dynamically based on operating conditions. The control module adjusts the engine torque setpoint according to the 4x4 device temperature and operational phase, optimizing the balance between crossing capability and thermal management to prevent overheating while maintaining progress
2Reliability
If the engine torque is limited to prevent overheating and maintain 4x4 mode, then the reliability is improved, but the crossing performance and traction capability are reduced
Solution Approach 1:
The system implements periodic action through phased torque management. During different phases of the off-road sequence (approach, crossing, exit), the control module applies different torque limiting strategies, allowing maximum torque when the device is cool and progressively reducing it as temperature increases, thereby maintaining crossing capability while preventing overheating
Solution Approach 2:
The system makes the torque limitation dynamic rather than static. The control module continuously adjusts the torque setpoint based on real-time temperature feedback and phase detection, optimizing performance at each moment rather than applying a fixed limitation, thus balancing reliability and productivity
3Productivity
If the torque transfer actuator is engaged to distribute torque to the rear axle, then the traction is improved, but the fuel consumption increases
Solution Approach 1:
The system applies partial action by engaging the torque transfer actuator only to the extent necessary for off-road traction. The control module calculates the minimum required torque transfer to maintain 4x4 operation and prevents excessive torque application that would unnecessarily increase fuel consumption, thus optimizing the balance between traction and energy use
Data Source
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AI summary
The invention relates to a system for limiting the engine torque of a four-wheel-drive motor vehicle, including an actuator that is controlled and configured to distribute the engine torque to the drive wheels, a computer means for calculating at least one variable characteristic of the operation of the vehicle, and a module for limiting the engine torque (2). In addition, the limitation system includes a means (21) for deactivating the module for limiting the engine torque according to the variables characteristic of the operation of the engine.