Double-Cable Motion Transmission Device Tension Adjustment
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Solution Overview
Problem
Existing double-cable rotating control assemblies face issues with variations in transmitted torsional force and hysteresis due to tolerances in Bowden cables and plastic parts, making it difficult to maintain consistent cable tension.
Innovation Solution
Incorporating a sleeve that surrounds the cables and is separate from the nipples, allowing the cables to be locked to the rotating pulley, which compensates for play and maintains consistent tension by being integral with the sleeve, thus isolating the effect of plastic part tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional Bowden cables with nipples are used to connect actuator devices, then the control assembly can be manufactured with simple structures, but tolerances in plastic parts cause variations in transmitted torsional force and hysteresis
Solution Approach 1:
The patent introduces a sleeve as an intermediary component between the cable assembly and the rotating pulley. This sleeve acts as a mediator that absorbs and compensates for tolerance variations in the plastic parts, thereby maintaining consistent cable tension and reducing hysteresis effects while preserving the overall simplicity of the control assembly structure.
Solution Approach 2:
The patent employs adjustable cable tension mechanisms that allow for parameter adjustment during assembly or operation. By enabling parameter changes in cable tension, the system can compensate for manufacturing tolerances in plastic parts, ensuring consistent torsional force transmission and reduced hysteresis without requiring extremely tight manufacturing tolerances.
2Ease of operation
If adjustable guide parts with resilient wings are used to control cable position, then cable tension can be adjusted, but it becomes difficult to place the guide part in the correct position
Solution Approach 1:
The patent designs the sleeve and cable assembly with self-aligning features that allow the components to automatically position themselves correctly during assembly. The sleeve's interaction with the rotating pulley and cable ends creates a self-positioning mechanism that eliminates the need for precise pre-positioning of guide parts, making the assembly process easier while maintaining manufacturing precision.
3Manufacturing precision
If plastic parts with tight tolerances are used to reduce hysteresis and torsional force variations, then cable tension consistency improves, but manufacturing cost and complexity increase
Solution Approach 1:
The sleeve serves as a tolerance-absorbing intermediary that decouples the relationship between plastic part dimensions and cable tension consistency. By introducing this intermediate component, the system can use standard-tolerance plastic parts while still achieving uniform cable tension and reduced hysteresis, thereby simplifying manufacturing without sacrificing performance.
Data Source
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AI summary
Double-cable rotating control assembly comprising a first and a second motion transmission device (12, 14), both provided with a respective case (22) and a respective rotating pulley (24) carried by the case (22), and a pair of cables (106, 108) fastened to the rotating pulleys (24) for connecting the motion transmission devices (12, 14) to each other, the cables being joined to each other by means of a first and a second nipple (112a, 112b) at each end of the pair of cables (106, 108). The pair of cables (106, 108) further comprises a sleeve (114) consisting of an element separate from the first and second nipple (112a, 112b), which surrounds the pair of cables (106, 108) and is placed adjacent to the first nipple (112a) and fastened to the seat (61) formed on the rotating pulley (24) of the first motion transmission device (12). The pair of cables (106, 108) is in a locked condition, in which the pair of cables (106, 108) is made integral with the sleeve (114).