Strain Wave Gearing as a Mechanical Fuse in Rotation Transmission
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Solution Overview
Problem
Prior rotation transmission mechanisms face issues with increased mass and assembly errors due to the addition of torque limiters and other components to prevent damage from overloading, which complicates the powertrain and affects its efficiency.
Innovation Solution
A rotation transmission mechanism utilizing a strain wave gearing as a speed reducer, where the strain wave gearing is designed to function as a mechanical fuse by adjusting the tooth depth, fastening force, or flexure of its gears to absorb overload, thereby preventing damage to other powertrain components without adding additional components like torque limiters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a torque limiter is added to the power transmission path to prevent overload damage, then the reliability of the powertrain is improved, but the device complexity and mass increase
Solution Approach 1:
The patent combines the speed reducer and torque limiting functions into a single integrated strain wave gearing unit. The strain wave gearing simultaneously performs speed reduction and acts as a mechanical fuse that limits torque transmission, eliminating the need for separate torque limiter components while maintaining both functions.
Solution Approach 2:
The strain wave gearing is designed to serve multiple functions: it acts as both the speed reducing mechanism and the torque limiting device. The same component that reduces speed also provides overload protection through its inherent torque characteristics, making the system more compact and less complex.
2Reliability
If a torque limiter is added to the power transmission path to prevent overload damage, then the reliability of the powertrain is improved, but the system mass increases
Solution Approach 1:
The patent combines the speed reducer and torque limiter functions into a single integrated strain wave gearing unit. The strain wave gearing simultaneously performs speed reduction and acts as a mechanical fuse that limits torque transmission, eliminating the need for separate torque limiter components and reducing overall system mass.
3Reliability
If additional components like torque limiters are added to the powertrain, then the protection against overload is improved, but the assembly precision requirements increase
Solution Approach 1:
The patent combines the speed reducer and torque limiter functions into a single integrated strain wave gearing unit. By eliminating separate torque limiter components, the number of assembly interfaces and potential sources of assembly error are reduced, simplifying the manufacturing and assembly process while maintaining overload protection.
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 strain wave gearing effectively absorbs overload, protecting other powertrain components from damage while maintaining its function as a speed reducer, reducing the risk of overloading without increasing system mass or complexity.
Implementation Method 1
a strain wave gearing provided with a rigid internally toothed gear, a flexible externally toothed gear disposed on the inner side of the internally toothed gear, and an ellipsoidally contoured wave generator fitted to the inner side of the flexible externally toothed gear
Data Source
AI summary
In a rotation transmission mechanism that transmits the rotational driving force of a motor to a load-side member via a speed reducer, a strain wave gearing is used as the speed reducer, and the allowable load torque of members in the powertrain other than the strain wave gearing is greater than a predetermined upper-limit load torque. The allowable load torque of the strain wave gearing is dictated by the ratcheting torque, which is set so as not to exceed the upper-limit load torque. In an overload state, ratcheting is generated in the strain wave gearing, so that the strain wave gearing functions as a mechanical fuse. Other power transmission members can be protected from an overload state without adding a separate member such as a torque limiter.