Switchable Ratcheting Wedge Clutch for Multi-Mode Torque Transfer
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Solution Overview
Problem
Ratcheting clutches lack a mechanism to seamlessly switch between locked, one-way, and freewheel modes, limiting their versatility and efficiency in torque transmission and braking applications.
Innovation Solution
A switchable ratcheting clutch design featuring an inner and outer race, a pivotable pawl, and a radially disposed cage with a ramp, allowing for contact transitions between different surfaces to enable locked, one-way, and freewheel modes through an actuator-driven rotation of the cage and ramp, facilitating non-rotatable or rotatable connections between the races.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional ratcheting clutch design is used, then the structure is simple, but the clutch cannot switch between locked, one-way, and freewheel modes, limiting versatility
Solution Approach 1:
The clutch design incorporates a pivotable pawl that can dynamically shift between different engagement positions with the ramp structure. The pawl rotates about a pivot axis to engage different surfaces (first surface for locked mode, second surface for one-way mode, no engagement for freewheel mode), enabling the system to adapt its mechanical constraints based on operational requirements rather than being fixed in a single configuration
Solution Approach 2:
The ramp structure is segmented into distinct functional surfaces: a first surface that slopes radially and circumferentially for locked mode engagement, and a second surface with different orientation for one-way mode engagement. This segmentation allows the single pawl-ramp interface to provide multiple operational modes by engaging different geometric features of the divided ramp surface
2Strength
If the pawl engages the first surface for locked mode, then load-bearing capacity is high, but kick-out forces may occur reducing reliability
Solution Approach 1:
The first surface of the ramp is designed with specific geometric properties - it slopes radially and circumferentially in a controlled manner to distribute contact forces. The pawl engagement geometry is optimized locally at the contact point to prevent kick-out forces while maintaining high load-bearing capacity, creating a specialized interaction zone that balances strength and reliability requirements
3Ease of operation
If the pawl is free of contact with the ramp for one-way mode, then relative rotation is enabled, but the mechanism becomes less stable
Solution Approach 1:
The second surface of the ramp acts as an intermediary engagement surface that provides partial constraint during one-way mode operation. When the pawl engages the second surface, it allows rotation in one circumferential direction while providing mechanical guidance and stability, serving as a mediator between complete freedom of rotation and full locked engagement
Data Source
AI summary
A switchable clutch, including: a first race including a pocket; a second race radially offset from the first race; a pawl including a portion disposed in the pocket and pivotable within the pocket; and a cage radially disposed between the first race and the second race and including a ramp. The ramp includes: a first surface; and a second surface sloping radially and circumferentially from the first surface. The first surface does not slope radially along a first circumferential direction. In a locked mode of the switchable ratcheting clutch, the pawl is in contact with the first surface and the outer race, and the first race and the second race are non-rotatably connected. In a freewheel mode of the switchable ratcheting clutch, the pawl is in contact with the second surface, and relative rotation of the first race with respect to the second race is enabled.