Four-Wheel-Drive Vibration Suppression via Thermal Load Control
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Solution Overview
Problem
Four-wheel-drive vehicles experience repeated self-excited vibration when starting on low friction surfaces, leading to potential damage from thermal overload in the drive force transfer device due to alternating slip between main and auxiliary drive wheels.
Innovation Solution
A four-wheel-drive vehicle control device that detects alternating slip states and reduces drive force transfer to auxiliary wheels via a drive force transfer device when a thermal load threshold is met, preventing damage by adjusting the torque transfer accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drive force is transferred to auxiliary drive wheels in four-wheel-drive state, then vehicle traction on low friction surfaces is improved, but thermal damage to drive force transfer device may occur due to repeated self-excited vibration
Solution Approach 1:
The control device monitors wheel speeds of main and auxiliary drive wheels, detects self-excited vibration states, and adjusts drive force transfer accordingly. This feedback mechanism allows the system to maintain four-wheel-drive traction while preventing thermal damage by reducing torque transfer when vibration is detected
Solution Approach 2:
The drive force transfer device dynamically adjusts its torque transfer characteristics based on real-time vibration detection. The system transitions between different operational states (normal four-wheel-drive, vibration suppression) to balance traction requirements with component protection
2Object-generated harmful factors
If engine torque or braking force is controlled to suppress self-excited vibration, then vibration is reduced, but vehicle start performance may be degraded
Solution Approach 1:
Instead of completely reducing engine torque or applying braking force, the system applies partial correction by selectively reducing drive force to auxiliary wheels only when vibration is detected. This partial action suppresses vibration while maintaining sufficient overall drive force for vehicle startup
3Reliability
If drive force transfer device operates continuously to maintain four-wheel-drive state, then wheel slip is suppressed, but clutch heating and damage may occur
Solution Approach 1:
The control system implements periodic monitoring of wheel speeds and conditional reduction of drive force transfer. By intermittently adjusting torque transfer based on vibration detection rather than continuous operation at full torque, the system suppresses wheel slip while allowing thermal management of the clutch
Data Source
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AI summary
A control device 10 is mounted on a four-wheel-drive vehicle 1, and includes a detector and a vibration suppression controller. The detector detects the occurrence of a vibrating state, in which drive wheels and auxiliary drive wheels slip alternately in a four-wheel-drive state in which a drive force is transferred to the auxiliary drive wheels, or the occurrence of a preliminary state for the vibrating state. The vibration suppression controller reduces the drive force which is transferred to the auxiliary drive wheels via a drive force transfer device 2 when the vibrating state or the preliminary state is detected by the detector. The vibration suppression controller reduces the drive force which is transferred to the auxiliary drive wheels on condition that a thermal load of the drive force transfer device 2 is less than a predetermined threshold.