Planetary Traction Gear With Elastic Frames for Radial Load Control
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Solution Overview
Problem
Existing fixed-ratio planetary traction gears face challenges in achieving precise radial positioning due to manufacturing tolerances, leading to uncontrolled radial loads and reduced operational life, especially at high rotational speeds and under heavy vibrations.
Innovation Solution
Incorporating elastic flat frames with controlled radial stiffness between the housing and planet wheel bearings, allowing for radial displacements and optimal distribution of radial forces, thereby compensating for manufacturing deviations and enhancing operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stay is positioned with eccentricity to achieve maximum ramp effect, then the ramp effect is improved, but the manufacturing precision requirements increase significantly
Solution Approach 1:
The patent introduces a preliminary positioning mechanism that establishes the radial position of planet wheels before operation. The stay with eccentricity e pre-positions the planet wheels relative to the sun shaft, creating the necessary ramp effect. The bearing slots are pre-configured with specific radial positions that accommodate this eccentric positioning, ensuring consistent performance without requiring extremely tight manufacturing tolerances on all components.
Solution Approach 2:
The patent changes the geometric parameter of the stay by introducing eccentricity e relative to the planet wheel center. This parameter change creates the ramp effect by varying the radial distance between the stay and planet wheel contact points during rotation. The eccentricity parameter allows the system to achieve the desired ramp effect while maintaining reasonable manufacturing tolerances through the relationship: ramp effect ∝ e × ω, where ω is the rotational speed.
2Manufacturing precision
If the stay is positioned with zero eccentricity to tolerate manufacturing tolerances, then the manufacturing precision requirements are reduced, but the ramp effect cannot be achieved
Solution Approach 1:
The bearing slots are pre-configured in the housing at specific radial positions that are optimized for the eccentric stay positioning. This preliminary arrangement of bearing slots allows the planet wheels to be positioned with acceptable manufacturing tolerances while still achieving the desired ramp effect through the eccentric stay geometry.
3Reliability
If tight manufacturing tolerances are applied to all components, then the ramp effect control is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies different precision requirements to different components based on their functional importance. The stay's eccentricity position and the bearing slot radial positions require high precision to establish the ramp effect geometry. However, other components such as the planet wheel bodies and housing can be manufactured with standard tolerances. This localized quality approach reduces overall manufacturing complexity while maintaining ramp effect control.
4Reliability
If the clearance in movable planet wheel is reduced to improve positioning, then the ramp effect is improved, but the radial load on bearings increases
Solution Approach 1:
The bearing slots are pre-positioned to provide optimal clearance that balances ramp effect and bearing load. The radial position of bearing slots is calculated to allow sufficient clearance for the eccentric stay to function while limiting excessive radial movements that would overload the bearings. This preliminary optimization of bearing slot positions resolves the contradiction between positioning precision and bearing load.
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 solution significantly reduces the impact of manufacturing tolerances on technical characteristics, extending the gear's operational life and improving its ability to operate under heavy external vibrations by maintaining consistent performance and reducing dynamic loads.
Implementation Method 1
Incorporating elastic flat frames with controlled radial stiffness between the housing and planet wheel bearings, allowing for radial displacements and optimal distribution of radial forces
Data Source
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AI summary
The gear is used for driving pneumatic turbomachinery while providing insignificant impact of the tolerances on the performance parameters leading to extended service life. It comprises a sun shaft (1) supported and driven by at least three planet wheels (2) rotating around their axes, on each side of which in axial direction there is an identical radially-elastic flat frame (7) in the shape of a flat planar closed-contour element having at least three annular bearing slots (7.1) with a cylindrical hole accepting the respective bearings (4) of the planet wheels (2). The bearing slots (7.1) are equidistant from the center of the frame (7) and each two adjacent bearing slots (7.1) are connected to one another via a respective curvilinear bridge (7.2) whose inner bend, towards the center, has an ear formed thereon (7.4) accepting the respective support pillar (6) fixed to the rear housing (5).