Four-Wheel Drive Clutch Torque Correction for Turning Bias
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing four-wheel drive systems with a multi-plate clutch between the rear-wheel differential gear and rear wheels experience bias torque during turning, leading to varying torque splits between front and rear wheels, affecting turning performance regardless of direction.
Innovation Solution
A control device with an electronic control unit that adjusts the friction clutch torque based on the vehicle's turning direction, using sensors to detect yaw rate and wheel speeds, to maintain a consistent torque split and improve turning performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-plate clutch is provided between the rear-wheel differential gear and the right rear wheel to adjust torque split, then torque distribution between front and rear wheels can be controlled, but bias torque occurs during turning causing turning-round performance to change according to turning direction
Solution Approach 1:
The electronic control unit calculates and corrects the clutch torque in advance based on detected turning direction before the turning maneuver is completed. By determining the turning direction and pre-adjusting the clutch torque compensation amount, the system ensures consistent turning-round performance regardless of turning direction.
Solution Approach 2:
The system changes the clutch torque parameter dynamically based on turning direction. When right-turning is detected, a first correction amount is applied; when left-turning is detected, a second correction amount (different from the first) is applied. This parameter adjustment compensates for bias torque and maintains consistent turning performance.
2Power
If friction clutch torque is increased to improve torque transmission to rear wheels, then four-wheel drive performance is enhanced, but fuel efficiency decreases due to increased friction losses
Solution Approach 1:
The friction clutch is engaged only partially or selectively based on actual driving conditions. The electronic control unit determines whether four-wheel drive is necessary and engages the clutch only when needed, rather than maintaining continuous engagement. This partial action provides sufficient torque transmission for four-wheel drive performance while minimizing friction losses and improving fuel efficiency during two-wheel drive operation.
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
The control device ensures consistent turning performance by adjusting clutch torque to compensate for bias torque, maintaining the desired torque split between front and rear wheels, and enhancing fuel efficiency by preventing dragging during two-wheel drive running.
Implementation Method 1
a friction clutch for adjusting a torque split to be transmitted to the front and rear wheels
Implementation Method 2
sensors to detect yaw rate and wheel speeds, to maintain a consistent torque split
Data Source
AI summary
A control device for a vehicle four-wheel drive device includes a drive source, front wheels, rear wheels, a rear-wheel differential gear, a friction clutch, and an electronic control unit. The electronic control unit is configured to correct a calculated clutch torque to decrease in a case where a four-wheel drive running is performed and it is determined that the turning direction is a direction in which the vehicle turns such that an outer wheel is a rear wheel on a side where the friction clutch is provided. The electronic control unit is configured to correct the calculated clutch torque to increase in a case where the four-wheel drive running is performed and it is determined that the turning direction is a direction in which the vehicle turns such that an inner wheel is the rear wheel on the side where the friction clutch is provided.