Planetary Traction Gear With Elastic Frames for Tolerance Compensation
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Solution Overview
Problem
Existing fixed-ratio planetary traction gears face challenges in achieving precise radial positioning and ramp effect 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 two identical, radially-elastic flat frames with controlled radial stiffness between the housing and planet wheels, allowing for radial displacements and optimal distribution of radial forces, which compensates for manufacturing deviations and enhances operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the stay is positioned with exceptional precision to achieve maximum ramp effect, then the ramp effect is maximized, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent changes the positioning parameter from fixed precise positioning to variable positioning with adjustable clearance. The movable planet wheel can shift radially within a controlled clearance range, allowing the system to adapt to manufacturing tolerances while maintaining functional performance through parameter variation rather than requiring exceptional precision.
Solution Approach 2:
The patent introduces dynamic adaptability by allowing the movable planet wheel to shift position dynamically within the clearance. This dynamic adjustment capability enables the system to compensate for manufacturing variations automatically, eliminating the need for static precise positioning and reducing manufacturing complexity.
2Manufacturing precision
If the clearance between stay and planet wheel center bore is minimized for precise positioning, then positioning accuracy improves, but the gear becomes sensitive to manufacturing tolerances and assembly difficulties increase
Solution Approach 1:
The patent employs dynamic positioning where the movable planet wheel can shift within a controlled clearance range. This dynamic capability allows the system to accommodate manufacturing tolerances in both the stay and planet wheel center bore while maintaining adequate positioning accuracy, thus improving ease of manufacture without sacrificing functional performance.
Solution Approach 2:
The patent creates a composite functional system combining the fixed stay structure with the movable planet wheel that has radial play. This composite approach integrates both precise positioning (through the fixed stay) and tolerance compensation (through the movable wheel's radial shift capability), resolving the contradiction between positioning accuracy and manufacturing ease.
3Manufacturing precision
If tight manufacturing tolerances are applied to all components, then the ramp effect is controlled precisely, but the operational life decreases due to stress concentration and the gear is more susceptible to vibration damage
Solution Approach 1:
The patent changes the system from requiring tight tolerances on all components to allowing controlled clearance variation. The movable planet wheel's radial play acts as a parameter that absorbs manufacturing variations, maintaining adequate ramp effect control while reducing stress concentration and improving operational life by eliminating the need for overly tight tolerances.
Solution Approach 2:
The patent incorporates beforehand cushioning by designing the movable planet wheel with intentional radial clearance. This clearance acts as a cushion that absorbs manufacturing tolerance accumulations and reduces stress peaks during operation, thereby extending operational life while maintaining sufficient ramp effect control without requiring tight tolerances on all components.
4Ease of manufacture
If the movable planet wheel is positioned with zero eccentricity to tolerate manufacturing deviations, then assembly ease improves, but the desired ramp effect cannot be achieved
Solution Approach 1:
The patent employs dynamic positioning where the movable planet wheel can shift radially within a controlled clearance to achieve the necessary eccentricity for ramp effect. This dynamic adjustment capability allows the system to start with easy assembly (zero initial eccentricity requirement) and then develop the required eccentric positioning through operational shifts, thus maintaining both assembly ease and ramp effect achievement.
Solution Approach 2:
The patent applies preliminary action by designing the movable planet wheel with pre-established radial clearance capability. This preliminary design feature enables the wheel to shift into the correct eccentric position during operation, achieving the ramp effect without requiring precise pre-positioning or high eccentricity during assembly, thus maintaining both assembly ease and functional reliability.
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 effectively minimizes 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 two identical, radially-elastic flat frames with controlled radial stiffness between the housing and planet wheels, allowing for radial displacements and optimal distribution of radial forces
Implementation Method 2
The outer ring is installed by pre-stretching it radially over the planet wheels, which position it radially and are driven by it
Data Source
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).