All-Wheel Drive Controller Torque Balance
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Solution Overview
Problem
All-wheel-drive vehicles experience noise (gear rattle) during coasting when the steering wheel is turned, due to differential rotation between front and rear wheels causing a torque imbalance, leading to gear vibration and noise, despite existing solutions that reduce clutch engagement force to mitigate noise, which can result in gear rattle when the accelerator pedal is turned on from off mode.
Innovation Solution
An all-wheel-drive-vehicle controller with a transfer clutch that adjusts torque distribution between main and sub driving wheels, using a first and second determination unit to identify conditions where torque applied to the drive gear is zero and hydraulic pressure is applied, and a control unit to apply hydraulic pressure to the reverse brake to adjust torque, preventing noise without reducing clutch engagement force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the engaging force of the transfer clutch is reduced to suppress gear rattle noise during coasting, then noise from the transmission mechanism is minimized, but gear rattle occurs when the accelerator pedal is turned on from off mode
Solution Approach 1:
The control unit applies preliminary action by detecting the coasting state and steering operation beforehand, then adjusts the transfer clutch engaging force to prevent gear rattle noise during coasting turns. This preliminary adjustment prevents the harmful effect (noise) before it occurs, while the system monitors readiness to restore engaging force when acceleration is needed
Solution Approach 2:
The transfer clutch engaging force is made dynamic rather than static. The control unit continuously adjusts the clutch engaging force based on real-time detection of vehicle state (coasting, steering angle, acceleration requests), allowing the system to optimize noise suppression during coasting while maintaining proper engagement when acceleration is required, thus preventing gear rattle in both scenarios
2Object-affected harmful factors
If the transfer clutch engaging force is reduced to minimize vibrations in the front-wheel output shaft, then noise from the transmission mechanism is suppressed, but the clutch engagement force becomes insufficient when acceleration is needed
Solution Approach 1:
The control unit implements feedback control by continuously monitoring vehicle state (accelerator position, steering angle, wheel speeds) and adjusting the transfer clutch engaging force accordingly. When coasting with steering input is detected, the system reduces engaging force to minimize vibrations and noise. When acceleration is requested or coasting ends, the system restores adequate engaging force, ensuring reliability is maintained while suppressing harmful vibrations during specific operating conditions
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
Effectively prevents gear rattle noise during coasting without reducing hydraulic pressure on the transfer clutch, maintaining clutch engagement force and ensuring smooth operation by balancing torque in the gear system.
Implementation Method 1
a second determination unit configured to determine whether a second condition in which hydraulic pressure is applied to the transfer clutch
Data Source
AI summary
An all-wheel-drive-vehicle controller includes: a drive gear coupled to a driving source; a driven gear meshed with the drive gear and coupled to main and sub driving-wheel axle shafts transmitting torques to main and sub driving wheels, respectively; a transfer clutch interposed between the driven gear and the sub-driving-wheel axle shaft and adjusting the torque transmitted to the sub driving wheel; a first determination unit determining whether a first condition in which a torque applied to the drive gear is substantially zero is satisfied; a second determination unit determining whether a second condition in which hydraulic pressure is applied to the transfer clutch and a torque applied to the driven gear is substantially zero is satisfied; and a control unit controlling a torque adjuster to adjust the torque applied to either one of the drive gear and the driven gear if the first and second conditions are satisfied.