Control Cable Thermal Expansion Management
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Solution Overview
Problem
Control cables with synthetic resin outer casings experience thermal expansion issues in high-temperature environments, leading to malfunction due to mismatched thermal expansion coefficients with metal inner cables, causing the outer casing to extend or contract and affecting the inner cable's operation.
Innovation Solution
A control cable design featuring a metal reinforcing wire with both ends fixed, a slidable synthetic resin outer casing that allows thermal deformation, and a metal inner cable, ensuring the outer casing's expansion or contraction does not impact the inner cable's length, while the reinforcing wire supports tensile forces and maintains flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a synthetic resin outer casing is used to reduce weight and improve flexibility, then the cable becomes more flexible and lighter, but the outer casing extends/contracts according to ambient temperature due to high thermal expansion coefficient
Solution Approach 1:
The outer casing is constructed as a composite structure combining synthetic resin with glass fiber reinforcement. The glass fiber mesh or strands are embedded within the synthetic resin matrix to create a composite material that maintains the flexibility and light weight advantages of the resin while adding dimensional stability and resistance to thermal expansion.
Solution Approach 2:
The thermal expansion coefficient of the outer casing is modified by incorporating glass fiber reinforcement into the synthetic resin. This changes the physical parameters of the material, reducing its thermal expansion coefficient to match that of the metal inner cable, thereby preventing differential expansion and contraction that would cause malfunction.
2Reliability
If the outer casing is reinforced by embedding reinforcing fibers to suppress thermal expansion, then thermal expansion is reduced, but the flexibility becomes impaired because the rigidity becomes too large
Solution Approach 1:
The reinforcement is applied locally and selectively within the outer casing structure. Glass fiber mesh or strands are embedded only in specific regions or orientations where dimensional stability is most needed, rather than uniformly throughout the entire casing. This localized reinforcement provides thermal expansion control while preserving flexibility in other areas.
Solution Approach 2:
The outer casing maintains a thin-walled, flexible shell structure made of synthetic resin with embedded glass fiber reinforcement. This design allows the casing to remain flexible and adaptable for routing along curved paths while the embedded glass fibers provide sufficient resistance to thermal expansion. The flexible shell structure enables the casing to bend and conform without breaking, unlike rigid reinforcement structures.
3Reliability
If steel wires are used as reinforcing fibers to suppress thermal expansion, then thermal expansion is controlled, but the flexibility becomes impaired because the rigidity becomes too large
Solution Approach 1:
The material composition of the reinforcement is changed from steel wire to glass fiber. This parameter change reduces the rigidity and thermal expansion coefficient of the reinforcement, allowing the outer casing to maintain flexibility while still providing sufficient dimensional stability. The glass fiber's lower modulus of elasticity compared to steel enables the casing to bend more easily without compromising its ability to resist thermal expansion.
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 prevents malfunctions by keeping the inner cable's length constant and maintaining operational effectiveness, with improved flexibility and compressive force resistance, ensuring reliable transmission of operating forces without impairing the outer casing's shape or guiding ability.
Implementation Method 1
the pipe made of synthetic resin is very high in thermal expansion coefficient compared with metal, if it is laid in an engine room etc. there is a problem that outer casing extends/contracts according to ambient temperature
Data Source
AI summary
A remote control device is provided, which includes a control cable. The control cable includes a reinforcing wire 11 of which the both ends are fixed by anchors 14, 14, an outer casing 12 made of synthetic resin so as to be slidable to the reinforcing cable, and so as not to constrain the thermal deformation in the axial direction based on the variation of ambient temperature, and an inner cable 13 made of metal having flexibility housed in the outer casing 12 slidably. In the both ends of the inner cable, cable ends 17, 17 coupled to an operating member and an operated member are firmly fixed.