Single-Layer Hollow Transmission Shaft for Pure-Torque Sensing
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Solution Overview
Problem
Conventional multi-layered transmission shafts in robot joints face challenges in accommodating communication wiring and accurately measuring wide-range torsional angles without affecting power transmission, especially during high-speed rotation.
Innovation Solution
A single-layered hollow transmission shaft with a multi-start helix structure, featuring left- and right-coiling helix sections with equal pitch and width, enables pure-torque transmission, reducing reaction forces and allowing for precise torque measurement without external components, while maintaining a large bore for wiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-layered transmission shaft structure is used, then the shaft can provide wide-range torsional angle output, but it becomes difficult to arrange communication wiring inside the shaft
Solution Approach 1:
The transmission shaft is divided into multiple layers with different functions: the outer shell provides structural support and torsional flexibility, while the inner hollow core creates a dedicated passage for communication wiring. This segmentation allows both wiring arrangement and torsional functionality to coexist without interference.
2Device complexity
If the transmission shaft has a hollow passage with large bore for wiring, then the shaft becomes a thin-wall structure, but this reduces the shaft's strength and torsional capability
Solution Approach 1:
The transmission shaft employs a composite structure combining a thin-walled hollow core for wiring with an outer reinforcement layer. The hollow core provides adequate wiring space while the outer layer restores and maintains the necessary torsional strength, allowing the shaft to simultaneously accommodate wiring and transmit torque effectively.
3Measurement precision
If external measuring components such as strain gauges are installed on the transmission shaft, then torque measurement is enabled, but the wiring becomes more complicated and measurement of wide-range torsional angle becomes difficult
Solution Approach 1:
The transmission shaft incorporates torque measurement functionality through its own structural deformation characteristics. The hollow shaft structure naturally exhibits measurable torsional deformation under torque load, allowing integrated sensing capabilities without requiring separate external measuring components or additional wiring systems.
4Ease of manufacture
If a single-layered hollow structure is used, then manufacturing is simplified and interior space is expanded, but the shaft may lack sufficient torsional rigidity
Solution Approach 1:
The single-layered hollow transmission shaft features non-uniform wall thickness distribution, with thicker sections positioned at critical locations to enhance local torsional rigidity while maintaining overall structural simplicity. This localized reinforcement allows the shaft to achieve adequate strength without compromising manufacturing ease or interior space.
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 simplifies manufacturing, reduces bearing loads, prolongs bearing life, and enhances torque measurement precision, facilitating high-speed rotation without compromising interior space or increasing complexity.
Implementation Method 1
The left-coiling multi-start helix section and the right-coiling multi-start helix section have an equal pitch, number of circles, number of starts of helix and width of helix, such that a torsional power inputted from the power-inputting end is transmitted to the power-outputting end by the at least one multi-start helix set of the hollow shaft body in pure-torque transmission
Data Source
AI summary
A single-layered hollow transmission shaft comprises a hollow shaft body. The hollow shaft body has a power-inputting end and a power-outputting end, which are formed at two opposite ends of the hollow shaft body, and at least one multi-start helix set. The multi-start helix set has a left-coiling multi-start helix section and a right-coiling multi-start helix section, which are arranged axially and have an equal pitch, number of circles, number of starts of helix and width of helix. By a single-layered structure and a structural design of the multi-start helix set, the single-layered hollow transmission shaft provides sufficient space for wiring of communication and can transmit power with pure torque while the shaft rotates, therefore increasing precision of torque detection, and can detect torque while rotating at high speed without installing any other external element and without affecting size of the space inside the shaft.