Two-Point Contact Internal Gear for Load Distribution and Lubrication
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Solution Overview
Problem
Conventional gear modules in high-precision speed reducers suffer from uneven load distribution and lack of lubrication, leading to increased wear and friction, which reduces durability and performance due to single-point contact and absence of a lubricating film.
Innovation Solution
A gear module design featuring an internal gear with grooves allowing two-point contact with pins, where each groove is formed with specific curvature radii and angles to distribute load and accommodate lubricant, enhancing durability and reducing friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gear module with single-point contact is used, then the structure is simple, but the load is concentrated on one contact point causing increased wear and reduced durability
Solution Approach 1:
The groove is divided into multiple contact regions (first and second contact points) instead of a single contact point. The groove includes a first groove portion and a second groove portion that contact the pin at different locations, distributing the load across multiple segments to reduce wear at any single point.
Solution Approach 2:
Different portions of the groove are designed with different geometric properties to optimize local contact conditions. The first groove portion has a first curvature radius while the second groove portion has a second curvature radius, allowing each local region to be optimized for its specific contact function.
2Reliability
If there is no space between the internal gear and pin, then the structure is compact, but no lubricating film can be formed causing increased friction and surface damage
Solution Approach 1:
The groove is designed with a predetermined lubricant storage space formed by the overlapping portion of circular arcs. This space is prepared in advance to hold lubricant before contact occurs, ensuring that lubrication is immediately available when the pin contacts the groove, preventing direct metal-to-metal contact.
3Manufacturing precision
If the groove is formed with simple geometry, then manufacturing is easier, but two-point contact with proper curvature and angle control is difficult to achieve
Solution Approach 1:
The groove is formed using curved geometric paths (circular arcs) instead of straight lines or simple shapes. The first and second groove portions are defined by circular arcs with specific curvature radii that pass through the pin center, ensuring proper contact geometry. This curved approach naturally achieves the required two-point contact configuration while maintaining manufacturability through standardized arc-based forming processes.
Data Source
AI summary
A gear module includes: an external gear eccentrically rotating and having a plurality of teeth formed along an outer peripheral surface thereof; and an internal gear having a plurality of grooves formed along an inner peripheral surface thereof, wherein each groove and each pin come into contact with each other with two contact points, and each groove is formed concavely from an overlapping portion between a first circular sector having a first curvature radius r1 larger than a curvature radius of each pin and a first circular arc coming into contact with one contact point and a second circular sector having a second curvature radius larger than the curvature radius of each pin and a second circular arc coming into contact with another contact point, the first curvature radius and the second curvature radius passing through a center point of each pin and having the same size as each other.