Harmonic Drive Wave Generator With Integrated Roller Carrier
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Solution Overview
Problem
The assembly of strain wave gearing systems, particularly harmonic drives, is time-consuming and costly due to the need for numerous rollers and complex bearing components, which also results in a large and heavy assembly with multiple points of failure.
Innovation Solution
A harmonic gear assembly featuring an epicyclic carrier unit with roller assemblies that form an elliptical wave generator, reducing the need for multiple rollers and bearing components by integrating them into a single, pre-assembled unit that can be easily mounted on the input shaft, allowing for a compact and lightweight design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple rollers and bearing components are used to drive the flex spline, then the harmonic drive provides high gear ratio and compact design, but the assembly becomes time-consuming and costly to manufacture with many points of failure
Solution Approach 1:
The patent combines multiple rollers and bearing components into a single integrated epicyclic carrier unit. This unit includes a carrier with multiple roller assemblies that are permanently mounted to the carrier, eliminating the need to assemble and retain numerous separate rollers with grease or other means. The integration reduces the number of parts and assembly steps while maintaining the functional requirements for driving the flex spline.
Solution Approach 2:
The roller assemblies are pre-assembled and permanently mounted to the carrier in advance, creating a pre-assembled epicyclic carrier unit. This preliminary action eliminates the need to assemble and retain numerous separate rollers during final assembly, reducing assembly time and complexity while ensuring proper positioning and retention of all roller components.
2Productivity
If around sixty or more rollers are assembled into two rows for each flex spline, then the flex spline can be properly driven, but the assembly process becomes time and cost intensive
Solution Approach 1:
The patent merges multiple roller assemblies into a single epicyclic carrier unit that is assembled as one integrated component. Instead of assembling and retaining sixty or more separate rollers, the unit is assembled once and then permanently mounted to the carrier, dramatically reducing assembly time and complexity while maintaining the necessary roller configuration for proper flex spline engagement.
Solution Approach 2:
The roller assemblies are pre-configured and permanently mounted to the carrier in advance of final assembly. This preliminary action creates a ready-to-install epicyclic carrier unit that eliminates the time-consuming process of assembling and retaining numerous individual rollers during final assembly, thereby improving productivity and ease of manufacture.
3Weight of moving object
If numerous rollers and bearing components are used, then the harmonic drive achieves high gear ratio, but the resulting assembly becomes relatively large and heavy
Solution Approach 1:
The patent combines multiple rollers and bearing components into a single integrated epicyclic carrier unit, eliminating the weight of numerous separate components and their retention mechanisms. The merged unit maintains the necessary roller configuration for high gear ratio performance while significantly reducing the overall assembly weight by removing redundant parts and retention systems.
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
This solution simplifies assembly and maintenance by reducing the number of parts and points of failure, while maintaining the advantages of strain wave gearing, such as high gear ratio and compactness, making it suitable for applications like aircraft flight control surfaces.
Implementation Method 1
the outer surface of the carrier unit at locations other than the first and second locations defines a minor axis
Implementation Method 2
an epicyclic carrier unit removably mounted around, and coaxial with the input shaft
Implementation Method 3
The force from the drive shaft is applied to the flex spline via rollers or ball bearings to press the flex spline against the circular outer ring
Implementation Method 4
A flexible toothed ring (a flex spline) is mounted about the wave generator and engages, and conforms to the shape of, the output shaft
Data Source
Figure 1~3
AI summary
A drive for a harmonic gear assembly, comprising an input shaft having a shaft axis (A) and an epicyclic carrier unit removably mounted around, and coaxial with the input shaft, the epicyclic carrier unit comprising a carrier (40) having an interior circumference designed to match the outer circumference of the shaft and further comprising a first roller assembly (42a, 50a) mounted at a first location around the circumference of the carrier unit and comprising a first roller shaft (42a) extending substantially parallel to the shaft axis and a first roller (50a) rotatably mounted around the first rotor shaft, and a second roller assembly mounted at a second location around the circumference of the carrier unit and comprising a second roller shaft (42b) extending substantially parallel to the shaft axis and a second roller (50b) rotatably mounted around the second rotor shaft, the first and second rollers extending radially outwards from the carrier to define a major axis between the radially outer surfaces of the first and second rollers, and wherein the outer surface of the carrier unit at locations other than the first and second locations defines a minor axis: