Wave Gear Device With Three-Dimensional Involute Tooth Profile
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wave gear devices face challenges in maintaining continuous meshing over the entire tooth trace, especially at high reduction ratios, and are prone to ratcheting due to insufficient load torque performance, with existing methods failing to adequately account for coning of external teeth.
Innovation Solution
A wave gear device with a three-dimensional contacting involute positive deflection tooth profile is developed, featuring an involute tooth profile with a low pressure angle less than 20°, where the external teeth are shifted to conform straight-line portions in axis-perpendicular cross sections, increasing effective tooth depth and preventing ratcheting by ensuring continuous meshing across the tooth trace.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard involute tooth profile with conventional pressure angle is used, then the tooth depth is sufficient for basic meshing, but the effective tooth depth is insufficient to prevent ratcheting at high reduction ratios
Solution Approach 1:
The patent changes the pressure angle parameter from the standard value (typically 20°) to a lower value (10°-15°), which increases the effective tooth depth and allows for better meshing engagement. This parameter change enables the gear teeth to maintain contact over a longer portion of the tooth height, preventing ratcheting at high reduction ratios while maintaining proper involute geometry for smooth power transmission.
Solution Approach 2:
The patent transitions from a two-dimensional tooth profile design to a three-dimensional contacting tooth profile that accounts for the coning effect along the tooth trace direction. By considering the spatial distribution of contact points and adjusting the tooth profile in multiple dimensions, the design achieves continuous meshing throughout the tooth trace, increasing the effective utilization of tooth depth and preventing ratcheting.
2Reliability
If the external teeth are designed without accounting for coning in the tooth trace direction, then the manufacturing is simpler, but continuous meshing cannot be maintained over the entire tooth trace
Solution Approach 1:
The patent applies different tooth profile characteristics at different locations along the tooth trace direction to account for the coning effect. By locally adjusting the tooth profile geometry based on the specific bending conditions at each position, the design achieves continuous meshing throughout the entire tooth trace while maintaining manufacturability through systematic design rules.
3Length of moving object
If a low pressure angle involute profile is adopted, then the effective tooth depth increases, but the manufacturing precision requirements increase due to the shifted tooth profile
Solution Approach 1:
The patent incorporates the tooth profile shift and three-dimensional contacting characteristics into the preliminary design stage, establishing the correct geometry before manufacturing. By pre-calculating and pre-adjusting the tooth profile to account for the low pressure angle and coning effects, the design ensures that standard manufacturing processes can achieve the required precision without excessive complexity.
Data Source
AI summary
In a wave gear device, an involute tooth profile with the low pressure angle α (<20°) is employed as a basic tooth profile of external teeth of a flexible external gear. In the principal section of the external teeth, the tooth depth thereof satisfies 2κ0mn=2(1+c) mn (deflection coefficient κ0=1+c, 0<c<0.5), which is larger than the standard one. The shifting of the teeth which takes into account coning is performed along the tooth trace direction of the external teeth, so that straight portions of a rack tooth profile on the respective sections perpendicular to the axis in the tooth trace direction of the external teeth are conformed as viewed along the tooth trace direction. The rack tooth profile of the involute tooth profile is a straight line.