Trochoid Gear Tooth Profiles for Stronger Angular Position Adjustment
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Solution Overview
Problem
Existing angular position adjusting mechanisms using internal and external gears with cycloid tooth profiles face challenges in ensuring high meshing strength due to large tooth flank inclination, leading to reduced load-bearing capacity.
Innovation Solution
The mechanism employs tooth profiles formed according to trochoid curves with specific design features such as constant distance and angle from loop shapes, relief flank portions, and curved surfaces to enhance meshing strength and durability, along with a backlash adjusting mechanism to optimize gear engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tooth profiles are formed according to cycloid curve with large tooth flank inclination, then a large meshing ratio is obtained, but meshing strength is reduced due to large load on the gear
Solution Approach 1:
The patent changes the fundamental geometric parameters of the tooth profile from cycloid curve to trochoid curve. This parameter change fundamentally alters the tooth flank inclination angle, reducing it from a large value in cycloid gears to a smaller value in trochoid gears, thereby simultaneously improving meshing strength while maintaining adequate meshing ratio
Solution Approach 2:
The trochoid curve introduces asymmetry in the tooth profile geometry compared to the symmetric cycloid curve. The basic point is positioned at a specific distance from the rolling circle circumference, creating an asymmetric profile that optimizes the distribution of contact stresses and reduces the inclination angle of the tooth flanks
2Strength
If tooth flanks are formed at constant distance from loop shapes of trochoid curve, then meshing strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
By defining the tooth flank position as a constant distance offset from the trochoid loop shape, the patent transforms a complex curved profile into a more manufacturable form with clear geometric parameters. This parameter-based definition simplifies the manufacturing process while maintaining the strength benefits of the trochoid geometry
3Reliability
If relief flank portions are added to form gaps between bottom land and top land, then durability is improved through reduced interference, but device complexity increases
Solution Approach 1:
The tooth profile is segmented into distinct functional portions: the main trochoid loop shape for load bearing, and the relief flank portions for interference prevention. This segmentation allows each portion to be optimized independently, with the relief portions strategically placed to create gaps that prevent bottom land interference while maintaining overall profile simplicity
Data Source
AI summary
In an angular position adjusting apparatus, tooth profiles of an internal gear 31 and an external gear 21 are formed according to loop shapes 74a and 84a of predetermined trochoid curves 74 and 84.