Wheel Disconnect Clutch Engagement Using Oscillating Torque
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Solution Overview
Problem
Conventional wheel disconnect clutches in all-wheel-drive vehicles face challenges in smooth engagement due to speed mismatches between the motor and wheel, leading to spinning losses and inefficient energy transfer.
Innovation Solution
A controller is programmed to command a series of motor speeds based on wheel speed with an alternating offset that oscillates between positive and negative values, facilitating the engagement of the clutch by aligning the relative speeds between the mating components, thereby reducing spinning losses and improving energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional clutch engagement is used without speed alignment, then the engagement process is simple, but speed mismatches cause spinning losses and inefficient energy transfer
Solution Approach 1:
The controller preliminarily aligns the rotational speeds of the motor and wheel before clutch engagement by commanding the motor to rotate at a speed matching the wheel speed. This preliminary speed synchronization prevents speed mismatches during engagement, eliminating spinning losses and ensuring efficient energy transfer from the outset.
2Productivity
If the motor speed is continuously adjusted to match wheel speed, then energy transfer efficiency is improved, but the control system complexity increases
Solution Approach 1:
The controller employs periodic monitoring and adjustment of motor speed relative to wheel speed. Rather than continuous complex control, the system periodically checks the speed difference and makes necessary adjustments, achieving efficient engagement while maintaining manageable control system complexity through rhythmic, interval-based control actions.
3Ease of operation
If the clutch engagement time is extended to allow speed synchronization, then engagement smoothness is improved, but the time required for activation increases
Solution Approach 1:
The controller performs preliminary speed synchronization before the actual clutch engagement occurs. By pre-aligning the motor and wheel speeds in advance, the system ensures that when engagement happens, the components are already matched, achieving smooth engagement without requiring extended engagement time.
4Loss of energy
If the motor and wheel speeds are precisely aligned before engagement, then spinning losses are reduced, but the control algorithm complexity increases
Solution Approach 1:
The controller uses feedback from speed sensors monitoring both motor and wheel rotational speeds to dynamically adjust motor speed. This closed-loop feedback mechanism automatically maintains speed alignment, reducing spinning losses while keeping the control algorithm manageable through straightforward sensor-based feedback rather than complex predictive algorithms.
Data Source
AI summary
A vehicle includes a primary axle powered by an actuator and a secondary axle powered by a motor and including a wheel and a clutch selectively coupling the wheel to the motor via mating components. A controller is electrically connected to the clutch and the motor. The controller is programmed to, in response to an engagement of the clutch being unsuccessful within a first duration of time, command a series of speeds to the motor based on wheel speed and an alternating offset that changes between positive and negative signs at predefined periods so that relative speeds between the mating components oscillate due to the alternating offset to jiggle the clutch into engagement.