Control Cable Armor Layer with Trapezoidal and Round Wire Configuration
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Solution Overview
Problem
Existing control cables face issues with varying freeplay length when bent, leading to increased stroke loss and reduced rigidity, as they either have high freeplay variation or low rigidity due to the design of their outer casings.
Innovation Solution
The control cable features an outer casing with a spiral armor layer composed of a trapezoidal wire and an intervening wire, where the trapezoidal wire has a narrow inside width and slanted sides, and the intervening wire is either round or oval, with specific ratios and angles optimized to balance rigidity and flexibility, along with a synthetic resin coating to reduce sliding resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pitch of the spiral armor layer is reduced to increase flexibility and reduce freeplay length variation, then the rigidity of the outer casing becomes small, but the stroke loss increases
Solution Approach 1:
The armor layer is segmented into alternating irregular shape wires and round wires, where each wire type contributes different mechanical properties. The irregular shape wires provide rigidity while the round wires allow relative movement to accommodate bending, thus maintaining both rigidity and flexibility without requiring pitch reduction.
Solution Approach 2:
The armor layer uses a composite structure combining irregular shape wires (providing rigidity) and round wires (providing flexibility), creating a composite material system that achieves both high rigidity and flexibility simultaneously, resolving the contradiction between these two properties.
2Ease of operation
If the thickness of the oval wire is reduced to increase flexibility, then the rigidity of the outer casing becomes small, but the stroke loss increases
Solution Approach 1:
The armor layer is segmented into alternating irregular shape wires and round wires, where each wire type contributes different mechanical properties. The irregular shape wires provide rigidity while the round wires allow relative movement to accommodate bending, thus maintaining both rigidity and flexibility without requiring pitch reduction.
Solution Approach 2:
The armor layer uses a composite structure combining irregular shape wires (providing rigidity) and round wires (providing flexibility), creating a composite material system that achieves both high rigidity and flexibility simultaneously, resolving the contradiction between these two properties.
3Loss of energy
If the outer casing is designed with only round wires in spiral winding, then the stroke loss is reduced, but the freeplay length varies when bending degree changes
Solution Approach 1:
The armor layer is segmented into alternating irregular shape wires and round wires. The irregular shape wires constrain the round wires to prevent excessive movement that would cause freeplay length variation, while the round wires still allow sufficient movement to minimize stroke loss.
Solution Approach 2:
Different wire types are placed in different positions within the armor layer. The irregular shape wires are positioned to provide structural support and constrain movement, while the round wires are positioned to allow bending accommodation, creating local quality differences that simultaneously reduce stroke loss and maintain freeplay length consistency.
Data Source
AI summary
An outer casing of a control cable has a small stroke loss and a small variation of freeplay length, even when the degree of bending varies. An outer casing is formed so that an armor layer of two threads configuration is formed, in which a trapezoidal wire made of metal and a round wire 17 or an oval wire are respectively aligned and wound spirally, and on the surface of the armor layer, a coating made of synthetic resin is provided. A control cable is formed so that an inner cable is inserted into the outer casing. The ratio of width in the axis direction of the round wire 17 or the oval wire to the width of the bottom of the trapezoidal wire 16 is 0.3 to 2, the ratio of the thickness of the round wire 17 or the oval wire to the thickness of the trapezoidal wire is 0.5 to 1, the ratio of the winding pitch P of the spiral to the outer diameter D2 of the armor layer 13 is 0.25 to 0.8.