Flat Strain Wave Gear with Bellows Diaphragm for Uniform Meshing
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Solution Overview
Problem
Strain wave gearings with a 'cup' profile require a minimum axial length to maintain torque capacity and transmission characteristics, and existing configurations with flexible and rigid gears facing each other axially struggle to achieve suitable meshing and sufficient rigidity for effective torque transmission.
Innovation Solution
A flat strain wave gearing design featuring a flexible gear with second teeth on a flat truncated-cone shape, a diaphragm with a bellows-form cross-section, and a wave generator with a rigid cam plate and cylindrical rollers to enhance supporting rigidity and ensure proper meshing between gears, allowing for reduced axial length while maintaining torque transmission characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the axial length is reduced to achieve a flat profile, then the device complexity is reduced and ease of operation is improved, but the torque capacity and transmission characteristics deteriorate
Solution Approach 1:
The patent changes the fundamental geometric parameters of the flexible gear, transitioning from a cylindrical shape to a flat truncated-cone shape with a specific vertex angle range (165°-180°). This parameter change allows the gear to achieve both reduced axial length and maintained torque capacity through the optimized conical geometry that distributes loads more effectively across the meshing surfaces.
Solution Approach 2:
The patent introduces a new dimensional configuration by using a flat truncated-cone shape instead of a traditional cylindrical form. This dimensional change from a vertical cylinder to a flattened cone allows the gear to operate effectively with reduced axial length while maintaining sufficient contact area between meshing teeth for reliable torque transmission.
2Strength
If the tooth width and diaphragm length are increased to ensure torque capacity, then the strength is improved, but the axial length increases and the flat profile is lost
Solution Approach 1:
The patent optimizes the diaphragm length and tooth width parameters within specific ranges that balance strength requirements with axial length constraints. The conical geometry allows for shorter tooth widths compared to cylindrical designs while maintaining adequate load-bearing capacity through the increased contact area provided by the tapered shape.
Solution Approach 2:
The patent applies local quality optimization by varying the thickness and structural properties of different parts of the flexible gear. The diaphragm and barrel part have optimized local geometries that provide sufficient flexibility and strength where needed, while maintaining overall compact dimensions. The conical shape naturally provides thicker sections at the base and thinner sections at the periphery, optimizing material distribution.
3Stability of the object's composition
If the flexible gear is made more rigid to improve supporting rigidity, then the reliability is improved, but the ease of flexing deteriorates
Solution Approach 1:
The patent optimizes the material and geometric parameters of the flexible gear to achieve an optimal balance between rigidity and flexibility. The conical shape with specific vertex angles and the optimized diaphragm structure provide sufficient radial rigidity to maintain gear tooth geometry while allowing the necessary axial flexing motion for wave generation and meshing.
Solution Approach 2:
The patent applies different structural characteristics to different parts of the flexible gear. The rigid boss provides a stable mounting interface with high supporting rigidity, while the diaphragm and barrel part maintain optimized flexibility for axial deformation. This local differentiation of structural properties allows the gear to simultaneously achieve both rigidity where needed and flexibility where required.
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 effective torque transmission with reduced axial length by ensuring high supporting rigidity and uniform meshing of gears, suppressing local deviations in load torque and maintaining ease of flexing, thus improving transmission characteristics.
Implementation Method 1
a flexible gear, which faces the rigid gear in the axial direction and in which second teeth that are capable of meshing with the first teeth in the axial direction are formed
Implementation Method 2
a wave generator that causes a tooth formation portion of the flexible gear where the second teeth are formed to flex in the axial direction
Data Source
AI summary
The flat strain wave gearing is provided with an axially arranged rigid gear, flexible gear and wave generator. The flexible gear forms a flat truncated cone shape, has a tooth formation portion connected via a bellows-shaped cross-sectional diaphragm to a rigid boss which is an output shaft linking part. The flat strain wave gearing can ensure axial flexibility of the tooth formation portion, and can enable teeth of the flexible gear to mesh favorably with teeth of the rigid gear in the axial direction in each position in the tooth trace direction. Local bias of the load torque in the meshing portion in the tooth formation portion can also be suppressed.