AWD Drive Mode Control Using Estimated Tire Load Thresholds
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Solution Overview
Problem
Existing drive control systems face challenges in quickly switching between two-wheel drive and four-wheel drive modes, especially under heavy load conditions, which affects fuel efficiency and temperature management while compromising traveling performance and steering stability.
Innovation Solution
A drive control device that includes an estimated longitudinal acceleration acquisition part, an estimated lateral acceleration acquisition part, and a drive mode selection part, which calculates an estimated tire load based on both longitudinal and lateral accelerations to determine the optimal drive mode, ensuring quick switching between two-wheel and four-wheel drive modes by setting threshold values within friction circles, and considering sudden acceleration and LSD operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the region for selecting two-wheel drive is expanded to suppress deterioration of fuel efficiency or temperature rise, then fuel efficiency is improved, but traveling performance and steering stability deteriorate
Solution Approach 1:
The drive mode selection is made dynamic by continuously monitoring wheel speed differences between main drive wheels and other wheels. When a speed difference exceeding a threshold is detected, the system automatically switches from two-wheel drive to four-wheel drive mode, allowing the system to adapt to changing driving conditions and maintain both fuel efficiency and traveling performance
Solution Approach 2:
The system uses feedback from wheel speed sensors to detect slipping conditions and automatically adjusts the drive mode accordingly. The control device receives wheel speed information, compares it between main drive wheels and other wheels, and uses this feedback to determine when to switch drive modes, ensuring optimal performance under varying conditions
2Temperature
If two-wheel drive is selected to suppress temperature rise of each part of the vehicle, then temperature management is improved, but traveling performance deteriorates
Solution Approach 1:
The system dynamically adjusts drive mode based on real-time wheel speed monitoring. When temperature rise is not critical and driving conditions are normal, two-wheel drive is maintained for better temperature management. When slipping is detected through wheel speed comparison, the system automatically transitions to four-wheel drive, ensuring traveling performance is maintained when needed
3Reliability
If the system quickly switches to four-wheel drive to improve traveling performance, then traveling performance is improved, but fuel efficiency deteriorates
Solution Approach 1:
The system maintains two-wheel drive mode during normal conditions to preserve fuel efficiency, and only switches to four-wheel drive when wheel speed differences indicate slipping or adverse conditions. This dynamic switching ensures that the higher fuel consumption of four-wheel drive is avoided unless absolutely necessary for maintaining traveling performance
Solution Approach 2:
The system changes the operational parameters of the drive system by switching between two-wheel and four-wheel drive modes based on detected conditions. By monitoring wheel speeds and comparing them against thresholds, the system changes the drive configuration parameter to optimize the balance between fuel efficiency and traveling performance
Data Source
AI summary
A drive control device includes: an estimated longitudinal acceleration acquisition part acquiring an estimated longitudinal acceleration of a vehicle based on an estimated driving force of the vehicle and a wheel speed of main drive wheels of the vehicle; an estimated lateral acceleration acquisition part acquiring an estimated lateral acceleration of the vehicle; an estimated tire load calculation part calculating an estimated tire load of the main drive wheels based on the estimated longitudinal acceleration and the estimated lateral acceleration; and a drive mode selection part selecting one of a two-wheel drive mode driven only by the main drive wheels and a four-wheel drive mode driven by both the main drive wheels and auxiliary drive wheels. When the estimated tire load calculated by the estimated tire load calculation part is lower than a two-wheel drive threshold value, the drive mode selection part selects the two-wheel drive mode.