Nutation Gear Reducer Power-Split Layout
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Solution Overview
Problem
Existing nutation reducers with knuckle bearings have complex structures, large volumes, and low power density, limiting their application in fields requiring high output torque and small volume.
Innovation Solution
A nutation reducer design with a power-split layout on both sides of the nutation generating mechanism, utilizing a tilted disc and symmetrically arranged nutation gear pairs, reduces volume and increases output torque by 100% while maintaining compactness and improving mechanical efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If knuckle bearing is adopted to realize nutation movement, then nutation movement is achieved, but structure becomes complicated and volume increases
Solution Approach 1:
The patent extracts and removes the knuckle bearing from the system, replacing it with a simplified nutation generating mechanism consisting of a nutation gear, non-nutation gear, and tilted disc. This extraction eliminates the complexity associated with knuckle bearings while maintaining the essential nutation movement function through gear meshing and tilted disc geometry.
Solution Approach 2:
The patent replaces the mechanical knuckle bearing system with a gear-based mechanical system. The nutation movement is generated through the meshing of nutation gear and non-nutation gear combined with the tilted disc, substituting the complex knuckle bearing mechanism with a more manufacturable and compact gear-based approach.
2Reliability
If knuckle bearing is adopted to realize nutation movement, then nutation movement is achieved, but volume becomes larger
Solution Approach 1:
By removing the knuckle bearing and its associated components, the patent significantly reduces the volume required for the nutation mechanism. The compact gear and tilted disc arrangement occupies less space while achieving the same nutation function, directly addressing the volume reduction requirement.
3Reliability
If knuckle bearing is adopted to realize nutation movement, then nutation movement is achieved, but power density becomes lower
Solution Approach 1:
The removal of the knuckle bearing eliminates a major source of friction and energy loss. The resulting gear-based nutation mechanism has lower mechanical losses, improving the power density by a factor of 2 or more compared to knuckle bearing systems, as the gear meshing and tilted disc mechanism are more efficient.
4Force
If output torque is doubled in existing nutation reducer, then output torque is increased, but volume should also be doubled
Solution Approach 1:
The patent introduces a power-split layout that segments the torque transmission path into multiple parallel channels. Two sets of nutation gear pairs work simultaneously, each handling a portion of the total torque. This segmentation allows the system to double the output torque while maintaining the same volume, as the torque is distributed across multiple gear pairs rather than requiring a single oversized gear set.
Solution Approach 2:
The patent combines multiple torque transmission paths by symmetrically arranging two sets of nutation gear pairs on opposite sides of the tilted disc. The torques from both sides are merged at the output, achieving doubled torque capacity within the same volume envelope through parallel torque paths.
5Force
If power-split layout with tilted disc is adopted, then output torque is increased by 100%, but thickness (axial) increased by 30-40%
Solution Approach 1:
The patent utilizes the axial dimension through the tilted disc geometry, where the tilt angle creates the nutation motion. While this does increase axial thickness by 30-40%, it enables the power-split configuration that doubles torque capacity. The tilted disc transforms rotational motion into nutation motion while accommodating multiple gear pairs in the radial direction, effectively trading some axial space for significant torque multiplication.
6Power
If single-stage reducer with transmission ratio 160 is designed, then transmission ratio is achieved, but friction loss between tooth surfaces is high
Solution Approach 1:
The patent segments the single high-ratio transmission stage into multiple lower-ratio gear pairs working in parallel. Instead of one gear pair with 160:1 ratio, two gear pairs with lower individual ratios work simultaneously, reducing the contact stress and friction loss in each gear pair while achieving the same overall transmission ratio through their combined effect.
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 achieves a 30-40% increase in output torque with a 30% reduction in volume and friction loss, enhancing power density and reducing equipment heating, making it suitable for high-power density applications.
Implementation Method 1
the annular elastic portion (103) in said annular spring film will transform the nutation movement of said nutation gears into single rotary movement of said output shaft by means of an elastic deformation of the annular elastic portion
Implementation Method 2
make the teeth of the nutation gear (400) roll on the teeth of the non-nutation gear (500)
Implementation Method 3
planar high-density ball bearing (200), which are respectively provided between the tilted disc (600) and the nutation gears (400) of each nutation gear pair, and two sides of the tilted disc (600) and the back sides of each nutation gear (400) of the two nutation gear pairs serve as the raceways of the planar high-density ball bearings (200)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A nutation reducer, to solve a problem that a knuckle bearing adopted in existing nutation reducers to perform nutation movement is complicate in structure, its volume is large, leading to low power density. A nutation reducer in this application includes: a case, two pairs of nutation gear pairs, each pair being disposed in the case and composed of a nutation gear and non-nutation gear in engagement, and the non-nutation gear being fixed in the case or integrated formed in the case; an output shaft, rotationally disposed in the case; two annular spring films, each nutation gear of the gear pair is connected to the output shaft through one annular spring film; a nutation generating mechanism disposed in the case, two nutation gear pairs being respectively disposed on both sides of the nutation generating mechanism. Power-split arrangement is applied in this application, symmetric layout of the nutation gear pairs is adopted. In this way, the working efficiency of the reducer is obviously improved, meanwhile the volume and weight of the reducer, and the heat generated in working process are reduced, and power density is improved.