Harmonic Pin Ring Tooth Geometry for Compact High-Torque Drives
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Solution Overview
Problem
Existing gear systems lack the ability to efficiently transmit large torques with high power density and flexibility in a compact design, while maintaining low play and rigidity, and offering a wide range of speed ratios and directional changes.
Innovation Solution
The Harmonic Pin Ring Drive (HPRD) system features a hollow shaft design with an inner ring, outer ring, and pin ring, where pins with a circular cross-section are deformed by a rotor to engage with both inner and outer teeth, ensuring continuous contact and providing a rotationally symmetrical gear with semi-circular tooth bases and elliptical or sine-superimposed circular pin trajectories for optimal torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional gear systems are used, then structural simplicity is maintained, but the ability to transmit large torques with high power density is insufficient
Solution Approach 1:
The gear system is segmented into multiple pins distributed around the circumference, each engaging with teeth on the inner and outer rings. This segmentation allows torque to be distributed across multiple contact points simultaneously, significantly increasing power density while maintaining a relatively simple overall structure.
Solution Approach 2:
The invention transitions from conventional single-plane gear engagement to a three-dimensional arrangement where pins move along elliptical or sine-superimposed circular trajectories. This dimensional change enables continuous contact between pins and teeth, maximizing power transmission capability within a compact volume.
2Adaptability or versatility
If conventional gear designs are used, then manufacturing simplicity is maintained, but flexibility in speed ratios and directional changes is limited
Solution Approach 1:
The gear system employs dynamic pin trajectories (elliptical or sine-superimposed circular paths) instead of fixed engagement points. This dynamic arrangement allows the same basic structure to achieve multiple speed ratios and directional changes by varying the trajectory parameters, providing versatility without requiring multiple specialized components.
Solution Approach 2:
The pin-ring mechanism serves multiple functions: it can transmit torque in different directions, achieve various speed ratios, and accommodate different load conditions all within a single unified structure. The universal design eliminates the need for separate mechanisms for each function, simplifying manufacturing while enhancing adaptability.
3Volume of moving object
If compact gear designs are used, then installation space is reduced, but maintaining low play and rigidity becomes difficult
Solution Approach 1:
The continuous contact between pins and teeth throughout the engagement cycle eliminates play and maintains rigid torque transmission. The pins remain constantly engaged with the tooth surfaces along their trajectories, ensuring uninterrupted force transmission and maintaining system rigidity within the compact volume.
Solution Approach 2:
The system combines rigid components (inner ring, outer ring, pins) with precisely controlled clearances and engagement geometries. This composite approach uses rigid materials throughout while achieving compact dimensions through optimized engagement patterns, maintaining both rigidity and space efficiency.
4Force
If pins with large cross-sections are used, then torque transmission capability is improved, but surface pressure on pins and teeth increases
Solution Approach 1:
By transitioning to three-dimensional pin trajectories (elliptical or sine-superimposed circular paths), the engagement is distributed over a longer path length. This dimensional change allows larger pin cross-sections for higher torque capacity while reducing peak surface pressure through extended contact duration and area.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present description discloses a harmonic pin ring gear system that has at least one inner ring (7) with external teeth and at least one outer ring (9) with internal teeth, and a pin ring (3) with pins that have a circular cross-section and a rotor with a transmitter (4) for pushing the pins of said pin ring (3) into the teeth of said outer ring and into the teeth of said inner ring. The shape of the teeth of the outer ring (9) and the shape of the teeth of the inner ring (7) are determined substantially by the envelope curve of the moving pins (1), each of the pins (1) being in engagement with the internal teeth of the outer gear (9) or in engagement with the external teeth of the inner gear (7).