Elastic Gear Speed Reducer for Higher Load and Longer Service Life
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Solution Overview
Problem
Existing speed reducers, particularly harmonic speed reducers, face challenges with reduced service life and bearing capacity due to the need for high forces to deform the flexspline, which is often made of medium-carbon alloy steel, limiting load-bearing capabilities and efficiency.
Innovation Solution
A speed reducer design featuring an elastic gear with an open structure, where the elastic gear is elastically deformable, allowing it to protrude towards an output member, driven by a fluctuating wheel, and engaging with output gear teeth to rotate the output member, using high-carbon alloy steel for enhanced strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the flexspline is pressed radially to form an elliptical shape for speed reduction, then speed reduction is achieved, but larger force is required which shortens service life and reduces efficiency
Solution Approach 1:
The patent employs a wave generator that dynamically deforms the circular spline from a circular shape to an elliptical shape during operation. This dynamic deformation allows the spline to engage with the harmonic gear teeth progressively, reducing the peak force required compared to static radial pressing, thereby extending service life while maintaining speed reduction functionality.
Solution Approach 2:
The patent changes the geometric parameters of the spline by transforming its cross-section from circular to elliptical through controlled elastic deformation. This parameter change enables the spline to accommodate varying engagement states with the harmonic gear, distributing the mechanical stress more evenly and reducing the overall force requirement, thus improving both speed reduction efficiency and service life.
2Strength
If the flexspline is made of medium-carbon alloy steel to ensure structural integrity, then strength is maintained, but bearing capacity and load-bearing capability are limited
Solution Approach 1:
The patent utilizes a composite structure where the circular spline is made of elastic material that can be dynamically deformed. This elastic material complements the medium-carbon alloy steel components, allowing the system to bear larger loads by distributing stresses across materials with different mechanical properties, thereby enhancing overall bearing capacity while maintaining structural integrity.
Solution Approach 2:
The dynamic deformation capability of the elastic circular spline allows it to adapt to varying load conditions. Under higher loads, the spline can deform more significantly to engage additional gear teeth, effectively increasing the bearing capacity beyond what a rigid medium-carbon alloy steel structure could achieve alone.
3Speed
If the wave generator applies larger force to deform the flexspline, then speed reduction is ensured, but efficiency is reduced
Solution Approach 1:
The patent optimizes the geometric parameters of the elliptical deformation, including the semi-major and semi-minor axes ratios, to achieve effective gear engagement with minimal force. By carefully controlling the deformation parameters, the system reduces energy loss while ensuring adequate speed reduction, improving overall efficiency.
Solution Approach 2:
The patent applies deformation locally at specific regions of the circular spline where gear engagement is most effective. Rather than uniformly deforming the entire spline, the wave generator concentrates elastic deformation in localized areas that directly contact the harmonic gear teeth, reducing the total force required and minimizing energy loss while maintaining speed reduction performance.
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
The design prolongs the service life and improves bearing capacity by reducing the force required for deformation, enabling the use of stronger materials and ensuring reliable operation with self-locking under reverse loads.
Implementation Method 1
at least a portion of the elastic gear which is located between the fluctuating wheel and the output member is elastic, and under the driving of the fluctuating wheel the portion is capable of elastically protruding toward the output member along the axis of the input shaft
Data Source
AI summary
A speed reducer has a housing (1), an input shaft (2), a fluctuating wheel (3), an output member and an annular elastic gear (5). The elastic gear (5) is located inside the chamber (10) and sleeved around the input shaft (2). An outer edge of the elastic gear (5) is fixed relative to the housing (1). The elastic gear (5) is located between the fluctuating wheel (3) and the output member, and under the driving of the fluctuating wheel (3), the portion is capable of elastically protruding toward the output member along an axis of the input shaft (2), so as to drive the output member to rotate around the central axis of the input shaft (2). An output power of the output member is balanced relative to an input power of the input shaft, so that the bearing capacity of the speed reducer is ensured.