Motorized Gear Reducer With Sunless Planetary Train
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Solution Overview
Problem
Conventional motorized gear reducers are bulky due to excessive axial length, which limits their application in environments with limited longitudinal length, and they often have low gear reduction ratios, making them inefficient for high torque applications.
Innovation Solution
A motorized gear reducer design featuring a multi-stage sunless planetary gear train with a support shaft and two ring gears, where the number of teeth in the rotatable ring gear differs from the stationary ring gear by a multiple of the planet gear sets, allowing for high gear reduction ratios while reducing the overall size by eliminating the sun gear and accommodating a support shaft within the planetary gear trains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional motorized gear reducer uses a planetary gear train mounted coaxially with the motor shaft, then speed reduction is achieved, but the axial length becomes excessive making the device bulky
Solution Approach 1:
The patent removes the sun gear from the conventional planetary gear train, extracting the problematic central component that contributes to axial length. This creates a sunless planetary gear mechanism where only planet gears and ring gears remain, significantly reducing the axial dimension while maintaining speed reduction functionality.
Solution Approach 2:
The patent reconfigures the planetary gear arrangement by eliminating the sun gear and allowing planet gears to mesh directly with two different ring gears (one stationary, one rotatable). This dimensional reorganization transforms the traditional coaxial layout into a more compact configuration that achieves the same speed reduction ratio with reduced axial length.
2Ease of manufacture
If the number of teeth of stationary and rotatable ring gears are made equal, then manufacturing is simplified, but gear reduction ratio becomes low
Solution Approach 1:
The patent explicitly changes the tooth count parameter of the ring gears, specifying that the stationary ring gear and rotatable ring gear must have different numbers of teeth. This parameter modification enables achievement of high gear reduction ratios while the patent simultaneously provides guidance on selecting appropriate tooth numbers to balance manufacturing feasibility with performance requirements.
Data Source
AI summary
A motorized gear reducer is provided with an axial support shaft in a housing; a speed reduction device including at least three stages of a sunless planetary gear train, each stage including a stationary ring gear, a rotatable ring gear served as a torque output, and a carrier on the support shaft and served as a torque input of each stage; planet gear sets, each in the carrier and including a first planet gear meshing the stationary ring gear, and a second planet gear meshing the rotatable ring gear, the rotatable ring gear of the last stage extending out of the housing to serve as a torque output of the speed reduction device; and a hollow motor surrounding the first stage and including a stator, a rotor surrounded and driven by the stator, and windings for rotating the rotor.