Roller-Wedge Cable Dial for Silent, Consistent Tension
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Solution Overview
Problem
Current dial-based cable tensioning systems are noisy and fail to maintain consistent pressure over time, leading to irritation and discomfort in applications such as headwear and footwear.
Innovation Solution
A silent, non-back-drivable tensioning system featuring a roller-and-wedge mechanism with a cam wheel and rollers that lock and unlock based on cable direction, combined with an angular restraint mechanism to prevent over-spooling and ensure consistent tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional dial-based cable tensioning system is used, then the structure is simple and easy to manufacture, but the system produces noise during operation and fails to maintain consistent tension over time
Solution Approach 1:
The patent employs a dynamic roller-and-wedge mechanism where rollers move along a cam profile to automatically adjust and maintain cable tension. The cam profile is designed to provide varying radial forces as the roller traverses its path, creating a dynamic balancing effect that compensates for cable elongation and maintains consistent tension without manual intervention.
Solution Approach 2:
The invention changes the geometric parameters of the cam profile to control the roller's motion and the resulting tension forces. By carefully designing the cam's curvature and slope, the system transforms rotational dial movement into controlled linear cable tension adjustments, maintaining optimal tension parameters throughout the adjustment range.
2Object-affected harmful factors
If a traditional dial-based cable tensioning system is used, then the device is simple in structure, but the system generates noise during dial manipulation
Solution Approach 1:
The patent replaces traditional friction-based mechanical engagement with a roller-and-wedge system that uses controlled rolling motion and geometric locking. The rollers roll along the cam surface without sliding friction, and the wedge geometry provides mechanical locking that prevents back-driving, eliminating the noise associated with traditional dial mechanisms while maintaining structural simplicity.
3Reliability
If a roller-and-wedge mechanism with cam wheel is used, then the system maintains consistent tension and operates silently, but the device complexity increases
Solution Approach 1:
The tensioning mechanism is segmented into distinct functional components: the cam wheel with its profiled surface, multiple rollers positioned at different locations, and the dial assembly. This segmentation allows each component to be manufactured separately using standard machining processes, with the cam wheel being a simple rotated extrusion that can be produced efficiently.
Solution Approach 2:
The cam wheel serves multiple functions simultaneously: it guides the roller motion, generates the tensioning force through its profile, and provides the mechanical advantage for tension adjustment. The rollers serve dual purposes by both sensing cable tension and actuating the cam mechanism, reducing the need for separate sensing and actuation components.
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 system provides silent operation, maintains consistent tension, and prevents cable from being pulled out without rotating the dial, ensuring the headwear or footwear remains securely in place without noise or pressure fluctuations.
Implementation Method 1
The roller can be configured to roll along the ramped surface to lock the cam wheel and the dial housing in response to the cable moving in a first direction
Implementation Method 2
The ramped surface is inclined relative to a line tangential to a point on the dial housing in contact with the roller
Data Source
AI summary
A cable tensioning system including a roller-and-wedge clutch is disclosed. The cable tensioning system can be used in an adjustable headband for a head-mountable display. In an example, a tensioning system includes a cable; a cam wheel including a roller opening, the cam wheel including a ramped surface adjacent the roller opening; a dial housing encircling the cam wheel; and a roller in the roller opening, the roller being configured to roll along the ramped surface, the roller being configured to lock the cam wheel and the dial housing when the cable moves in a first direction, the roller being configured to unlock the cam wheel and the dial housing when the cable moves in a second direction opposite the first direction.