Planetary Gear Rolling-Tooth Structure for Low-Slip Power Transmission
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Solution Overview
Problem
In planetary gear devices, slippage between external and internal gears leads to reduced power transmission efficiency and wear, affecting the durability of the teeth.
Innovation Solution
The design includes first and second internal gears with rotating bodies having roller members and pin members, which are supported by bearings and connected to external gears, preventing sliding and reducing friction through an epitrochoid parallel curvilinear tooth profile, and using thermally solidified grease for lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If involute gears are used for external and internal gears, then the gear structure is simple and easy to manufacture, but slippage is generated between teeth leading to reduced power transmission efficiency and increased wear
Solution Approach 1:
The patent replaces the traditional involute gear tooth profile with a cycloidal tooth profile. The cycloidal profile enables rolling contact between gear teeth instead of sliding contact, substituting the mechanical interaction mechanism to eliminate slippage while maintaining manufacturing feasibility through the defined mathematical profile equations.
Solution Approach 2:
The patent changes the fundamental geometric parameters of the gear teeth by adopting cycloidal curves (epicycloid for external gears, hypocycloid for internal gears) instead of involute curves. This parameter change in the tooth profile geometry transforms the contact mechanism from sliding to rolling, improving power transmission efficiency.
2Device complexity
If involute gears are used for external and internal gears, then the gear structure is simple, but the teeth are worn by slippage reducing durability
Solution Approach 1:
The patent substitutes the sliding contact mechanism of involute gears with a rolling contact mechanism using cycloidal tooth profiles. This mechanical substitution eliminates the relative sliding motion that causes wear, thereby improving tooth durability and reliability while keeping the overall gear structure relatively simple.
Solution Approach 2:
By changing the tooth profile parameters from involute to cycloidal geometry, the patent fundamentally alters the contact characteristics between gear teeth. The cycloidal profile ensures that teeth engage and disengage through rolling motion, preventing wear accumulation and extending the service life of the gear components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances power transmission efficiency, reduces wear, and improves durability by minimizing friction and tooth sliding, allowing for various reduction ratios and easier manufacturing with fewer parts.
Implementation Method 1
a rolling element which is disposed between the pin member and the roller member
Data Source
Figure 1
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AI summary
Provided is a planetary gear device which effectively transmits power. A planetary gear device includes a first internal gear and a second internal gear, a first external gear which meshes with the first internal gear, a second external gear which meshes with the second internal gear, and an eccentric body which circumferentially moves the first external gear and the second external gear. The first external gear and the second external gear each independently have external teeth and are connected to each other so as to integrally rotate with each other, the first internal gear and the second internal gear each independently have internal teeth, one of the first internal gear and the second internal gear is connected to a stationary side, and the other thereof is connected to an output side, and each of the first internal gear and the second internal gear has internal teeth which are constituted by a support body, and a rotating body rotatable to the support body.