Torque Transmission Device With Flexible Earth Ring
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Solution Overview
Problem
Existing torque transmission devices, such as torque limiters and freewheels, are heavy, costly, and require corrosion-protection treatments due to their sizeable earth rings made of case-hardened steel, which are not corrosion-resistant, and they fail to efficiently manage torque in aerospace applications where weight reduction and complexity minimization are critical.
Innovation Solution
A torque transmission device with a thinner, flexible earth ring that contacts the housing at a curved surface interface, allowing torque transmission via friction, and featuring a bearing cage with rollers that apply torque to the earth ring, which is then transmitted to the housing, thereby reducing weight and eliminating the need for corrosion treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a sizeable earth ring made of case-hardened steel is used to transmit torque, then the torque transmission capability is improved, but the weight of the device increases significantly
Solution Approach 1:
The patent changes the material parameters of the earth ring by using aluminum alloy instead of case-hardened steel, and optimizes the geometric parameters including the thickness ratio (earth ring thickness to housing thickness between 0.2-0.5) and the contact area parameters to achieve sufficient torque transmission with reduced weight
Solution Approach 2:
The patent employs composite material construction with an aluminum alloy earth ring mounted within a housing, creating a hybrid structure that combines the advantages of different materials to achieve both weight reduction and structural integrity for torque transmission
2Strength
If case-hardened steel is used for the earth ring to handle high stresses, then the strength is improved, but corrosion resistance deteriorates requiring expensive protection treatments
Solution Approach 1:
The patent changes the material composition parameters by selecting aluminum alloy with specific compositional ranges (aluminum 85-95%, zinc 3-10%, magnesium 1-5%) that inherently provide both the required mechanical strength and excellent corrosion resistance, eliminating the need for additional corrosion protection treatments
3Strength
If the earth ring thickness is increased to handle contact stress from bearings, then the strength is improved, but the weight and complexity of manufacture increase
Solution Approach 1:
The patent optimizes the thickness parameter of the earth ring within specific ranges (earth ring thickness 5-20mm, housing thickness 10-40mm) to achieve the optimal balance between contact stress bearing capacity and manufacturing simplicity, avoiding excessive thickness that would increase complexity
Solution Approach 2:
The patent applies local quality enhancement by providing reinforcement ribs or strengthening features at specific locations on the earth ring where contact stresses from bearings are most intense, rather than uniformly increasing the entire earth ring thickness, thus maintaining manufacturing simplicity while achieving required strength
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 results in a lighter, more cost-effective torque transmission device that effectively manages torque in aerospace applications by reducing the earth ring's weight and eliminating the need for corrosion treatments, while maintaining structural integrity and preventing slip within the housing.
Implementation Method 1
an outer surface of the earth ring contacts an inner surface of the housing along a contact area, thereby providing a frictional interface at the contact area for transmitting torque from the earth ring to the housing
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3~4
AI summary
A torque transmission device (200) comprises: an input drive shaft (30), a housing (10'), an earth ring (20'), a bearing cage (50), and a plurality of bearings (40) held by the bearing cage between an inner surface (24) of the earth ring (20') and an outer surface of the input drive shaft (30). The earth ring (20') is mounted within the housing (10') such that an outer surface (22) of the earth ring (20') contacts an inner surface (12) of the housing (10') along a contact area (15), thereby providing a frictional interface at the contact area (15) for transmitting torque from the earth ring (20') to the housing (10').