Multipoint Contact Bevel Gears With Conjugate Curves for Lower Wear
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Solution Overview
Problem
Conventional gear pairs, such as cylindrical, bevel, worm, and hypoid gears, suffer from low bearing capacity and severe abrasion due to line contact and high sliding rates, which limits their performance in high-speed and high-load applications, necessitating running-in processes that increase manufacturing costs.
Innovation Solution
A conjugate-curve-based multipoint contact bevel gear pair is developed, featuring convex and concave tooth gears with multiple contact points distributed across different cross-sections, utilizing circular helix curves to achieve smooth multipoint contact, thereby enhancing contact strength and reducing sliding rates without the need for running-in.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional gear pairs with line contact are used, then the structure is simple and easy to manufacture, but the bearing capacity is low and tooth face abrasion is severe
Solution Approach 1:
The patent applies spherical tooth profiles with circular arc conjugate curves instead of conventional straight or involute profiles. The convex and concave spherical surfaces with curved geometries enable point contact meshing, increasing contact density and bearing capacity while maintaining manufacturability through standardized spherical surface generation methods
2Ease of manufacture
If conventional gear pairs with line contact are used, then the manufacturing process is simple, but the sliding rate between tooth faces is large causing severe abrasion
Solution Approach 1:
The spherical tooth profiles with circular arc conjugate curves create point contact instead of line contact, significantly reducing the sliding rate between tooth faces. The curved spherical surfaces enable more favorable contact conditions that reduce friction and abrasion, eliminating the need for running-in processes while maintaining simple manufacturing
Solution Approach 2:
The patent changes the fundamental contact parameter from line contact to point contact through spherical tooth profiles. This parameter change reduces the sliding velocity and contact stress, thereby reducing tooth face abrasion and eliminating the need for running-in processes
3Strength
If point contact gears with single contact point are used, then the contact strength is high, but the contact pattern is small requiring running-in process
Solution Approach 1:
The patent segments the single contact point into multiple contact points along the tooth width direction by distributing circular arc conjugate curves at different positions. This creates a multipoint contact pattern that maintains high contact strength while eliminating the need for running-in, thereby reducing manufacturing costs
Solution Approach 2:
The patent extends the contact from a single point in three-dimensional space to multiple points distributed along the tooth width dimension. By arranging circular arc conjugate curves at different positions along the tooth width, the contact pattern is expanded from one point to multiple points, maintaining high contact strength while enabling direct use without running-in
4Area of stationary object
If soft tooth faces or medium-hard tooth faces are used for running-in, then the contact pattern can be increased, but the manufacturing cost increases and contact strength decreases
Solution Approach 1:
The patent segments the contact into multiple points along the tooth width direction through distributed circular arc conjugate curves, achieving a larger effective contact pattern without requiring running-in processes. This allows the use of hard tooth faces, maintaining both low manufacturing cost and high contact strength
Solution Approach 2:
The patent incorporates the multipoint contact characteristic directly into the gear design and manufacturing process, achieving the desired contact pattern beforehand without requiring a separate running-in process. This preliminary action eliminates the need for soft or medium-hard tooth faces, allowing direct use of hard tooth faces at lower cost
Data Source
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AI summary
The present invention discloses a conjugate-curve-based multipoint-contact bevel gear pair. It includes a convex tooth gear and a concave tooth gear which are of multipoint contact, and the meshing surface of the convex tooth gear or the concave tooth gear is a tubular surface. The contact curve formed by the contact points on the tooth profile of the convex tooth gear and the contact curve formed by the contact points on that of the concave tooth gear are conjugate curves. The meshing manner of the conjugate-curve-based multipoint-contact bevel gear pair of the present invention is that the convex tooth gear and the concave tooth gear are simultaneously in a multipoint contact situation. All the contact traces of the contact points on respective tooth surfaces are smooth space curve. Such transmission inherits meshing characteristics of conjugate curves, and the tooth profile of point contact has high contact strength, large bearing capacity, a high transmission efficiency, a low lubricating oil temperature rise, a greatly decreased sliding rate, a small abrasion.