Conjugate-Curve Cylindrical Gears With Multipoint Tooth Contact

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Solution Overview

Problem

Traditional gear transmission systems face limitations in load capacity, sliding rate, and wear due to convex-to-convex contact styles, and existing point contact gears have only single-point contact, which is not suitable for high-speed and heavy-load applications.

Innovation Solution

A multipoint contact cylindrical gear pair based on conjugate curves is developed, featuring multiple meshing points distributed across different cross-sections, with specific contact curves and surfaces defined by equations that enable smooth transition and high contact strength, allowing for one-point, two-point, or multipoint contact depending on requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional spiral gear or worm gear drive with convex-to-convex contact is used, then the structure is simple, but the load capacity is low and sliding rate is large

Engineering Contradiction:
Improveload capacityVSAvoidtooth profile complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The tooth profile is divided into multiple contact zones along the meshing line, creating multiple discrete contact points instead of a single contact point. This segmentation allows the load to be distributed across multiple points, increasing overall load capacity while maintaining a manageable tooth profile structure

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from traditional two-dimensional tooth profile contact to three-dimensional multipoint contact by introducing contact points at different positions along the tooth height and width. This dimensional expansion allows simultaneous engagement of multiple points, significantly increasing load capacity without excessive profile complexity

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Strength

If single-point contact gear is used, then the manufacturing is simpler, but the contact strength is insufficient for high-speed and heavy-load applications

Engineering Contradiction:
Improvecontact strengthVSAvoidmeshing pair complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

Multiple contact points are merged into a unified meshing system where all points work simultaneously to transmit load. The tooth profiles are designed so that multiple contact points engage at the same time, combining their load-bearing capabilities to achieve high contact strength for heavy-load applications

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention changes the contact parameters by introducing multiple contact points with specific spacing and positioning along the meshing line. By adjusting parameters such as contact point distribution, tooth geometry, and profile curvature, the system achieves optimized contact strength while controlling manufacturing complexity

Inventive Principle:
Principle #35Parameter changes

3Reliability

If convex-to-convex contact style is used, then the manufacturing is easier, but the wear of tooth profiles is large

Engineering Contradiction:
Improvetooth profile durabilityVSAvoidtooth profile manufacturing
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Different regions of the tooth profile are designed with locally optimized characteristics. The contact zones are positioned and shaped to distribute wear across multiple points, while non-contact regions maintain simpler geometries for ease of manufacture. This local differentiation improves durability without requiring complex manufacturing throughout the entire tooth profile

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3348869B1Conjugate curve-based cylindrical gear meshing pair having multiple contact points
Publication Date: 2021.03.10 CHONGQING UNIV
  • EP3348869B1 patent drawingFigure 1~3
  • EP3348869B1 patent drawingFigure 4~7
  • EP3348869B1 patent drawingFigure 8~10

AI summary

The present invention discloses a multipoint contact cylindrical gear meshing pair based on conjugate curves, it includes a convex gear and a concave gear which show the multipoint-contact mutually, and the meshing tooth profile of the convex gear and the concave gear is a tubular surface, the contact curve formed by the meshing points on the tooth profile of the convex gear and the contact curve formed by the meshing points on the concave gear are conjugate curves, the engagement form of the multipoint contact cylindrical gear meshing pair based on conjugate curves of the present invention is that the convex gear tooth surface and the concave gear tooth surface are simultaneously in multipoint contact, all the contact traces of the contact points on respective tooth profiles are smooth space curves. Such gear transmission inherits meshing characteristics of conjugate curves, and the point-contact tooth profile has the advantages of the high contact strength, large bearing capacity, high transmission efficiency, low temperature rise of lubricating oil, low sliding rate, and small wear, etc.