Wedge Clutch Demagnetization via Reverse Polarity Current
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Solution Overview
Problem
A wedge clutch in a motor vehicle often fails to return to its one-way clutch mode after deenergizing, resulting in a residual magnetic field that keeps it in a freewheel mode even after being powered off, due to strong residual magnetic fields.
Innovation Solution
An electric circuit with a clutch coil, power relay, H-bridge, and microcontroller is used to magnetize and demagnetize the clutch coil by sending current in specific directions, allowing the wedge clutch to switch between locked and unlocked states, ensuring it returns to the one-way clutch mode by demagnetizing the clutch coil through a controlled signal flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current is sent through the clutch coil to magnetize it for wedge clutch operation, then the wedge clutch can be locked or unlocked as needed, but a strong residual magnetic field remains after deenergizing that prevents the clutch from returning to one-way clutch mode
Solution Approach 1:
The patent applies reverse polarity current through the clutch coil to actively demagnetize the residual magnetic field. By sending current in the opposite direction through the same clutch coil, the magnetic field is reversed and neutralized, converting the harmful residual magnetism into a beneficial demagnetization process that enables reliable mode switching.
2Ease of operation
If the wedge clutch is designed to operate in freewheel mode during certain conditions, then the transmission can achieve smooth shifting and reduced friction, but the clutch may fail to return to one-way clutch mode after deenergizing due to persistent magnetic field
Solution Approach 1:
The control module monitors the operational state of the wedge clutch and automatically applies reverse polarity current when detecting that the clutch fails to return to one-way clutch mode. This feedback mechanism detects the persistent magnetic field condition and triggers the demagnetization process, ensuring reliable mode transitions while maintaining ease of operation during freewheel conditions.
3Speed
If the clutch coil is energized strongly to ensure reliable locking and unlocking, then the wedge clutch responds quickly and reliably, but the residual magnetic field becomes stronger and prevents return to one-way clutch mode
Solution Approach 1:
The patent employs reverse polarity current application to demagnetize the clutch coil after operation. By inverting the current direction through the same coil, the strong magnetic field used for reliable locking/unlocking is actively cancelled out, allowing fast response while eliminating the harmful residual field that would otherwise prevent mode recovery.
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 solution effectively manages the magnetic field of the wedge clutch, ensuring it can transition back to the one-way clutch mode after deenergizing, preventing freewheel mode persistence and maintaining proper operational states.
Implementation Method 1
a clutch coil configured to magnetize or demagnetize based on a direction of current received at the clutch coil
Data Source
AI summary
A transmission control unit for a wedge clutch, comprising a controller configured to send one or more signals to a switch connected to the wedge clutch, the switch being configured to demagnetize the wedge clutch by sending current in a first direction to a coil of the wedge clutch.