Folded Strip Coupling for Misalignment and Low-Friction Torque Transfer
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Solution Overview
Problem
Existing couplings face challenges in achieving low friction, dynamic stress resistance, and cost-effectiveness while accommodating misalignment between rotary components, particularly in aerospace applications, where weight minimization and ease of assembly are critical.
Innovation Solution
A coupling design featuring a strip with alternating outer and inner folds, connected to female and male members via pivotal connections, allowing for compression and accommodating misalignment through elastic deformation, made from materials with lower Young's modulus and higher thermal expansion than the members, facilitating torque transfer and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional rigid coupling designs are used to ensure structural strength, then dynamic stress resistance is improved, but friction increases and weight increases
Solution Approach 1:
The coupling employs a flexible strip with alternating outer and inner folds that can elastically deform under load. This flexible structure replaces traditional rigid coupling elements, allowing the coupling to accommodate dynamic stresses through elastic deformation while maintaining low friction contact without requiring lubrication or cooling systems.
Solution Approach 2:
The patent utilizes materials with specific parameter characteristics - the strip is made of material with lower Young's modulus and higher thermal expansion coefficient than the male and female members. This parameter selection allows the strip to be more compliant under dynamic loads, reducing stress concentration and friction while the thermal expansion properties facilitate assembly through thermal growth.
2Ease of operation
If alignment tolerance is increased to ease assembly, then ease of operation is improved, but torque transfer efficiency deteriorates
Solution Approach 1:
The coupling design incorporates a dynamic flexible strip that can adapt its shape during operation. The alternating folds allow the strip to deform and accommodate misalignment between the male and female members, maintaining effective torque transfer even when assembly alignment is not perfectly precise. This dynamic adaptation resolves the contradiction between ease of assembly and torque transfer efficiency.
3Strength
If material with high Young's modulus is used to ensure stiffness, then strength is improved, but ease of manufacture and assembly deteriorates
Solution Approach 1:
The patent deliberately selects material parameters opposite to traditional rigid coupling designs - the strip uses material with lower Young's modulus than the male and female members. This lower stiffness material is easier to form into the complex folded geometry and allows for simpler manufacturing processes. The material's lower stiffness also facilitates assembly by allowing the strip to flex into position, while the overall structure maintains sufficient strength through its geometric configuration.
4Strength
If complex cooling and lubrication systems are added to reduce friction, then dynamic stress resistance is improved, but device complexity increases
Solution Approach 1:
The flexible strip coupling operates without external lubrication or cooling systems. The material selection and fold geometry enable the coupling to self-regulate friction and heat generation through elastic deformation. The strip's ability to flex and conform to misalignment reduces sliding friction, and the inherent elasticity provides thermal management without requiring additional cooling components, thus resolving the contradiction between dynamic stress resistance and system complexity.
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 design enhances torque transfer efficiency, accommodates misalignment, reduces manufacturing and assembly complexity, and minimizes weight, while maintaining performance under varying operational conditions.
Implementation Method 1
allowing for compression and accommodating misalignment through elastic deformation
Implementation Method 2
the strip has a coefficient of thermal expansion larger than a coefficient of thermal expansion of a material forming the female member and male member
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
The coupling (30; 230) can have a female member (32; 232) having a plurality of female member connections (266) circumferentially arranged along a radially inner face (38; 238); a male member (34; 234) having a plurality of male member connections (268) circumferentially arranged along a radially outer face (40; 240); and a coupling member (231) extending annularly around the axis (264), the coupling member (231) having a strip (233), the strip (233) having, circumferentially relative the axis (264), an alternating sequence of outer folds (260) and inner folds (262), the outer folds (260) connected to the female member (32; 232) via respective ones of the female member connections (266), the inner folds (262) connected to the male member (34; 234) via respective ones of the male member connections (268), the inner folds (262) being circumferentially offset from the outer folds (260) in a given angular direction.