Frustoconical Epicyclic Traction Transmission With Adjustable Preload
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Solution Overview
Problem
Existing epicyclic traction transmissions suffer from low torque density and mechanical efficiency due to fixed preload systems that result in excessive wear and reduced lifespan, and variable preload systems introduce alignment issues and mechanical play.
Innovation Solution
The design incorporates frustoconical rolling elements that allow axial preload application, enabling variable preload adjustment to enhance torque density and mechanical efficiency while maintaining alignment through specialized lubrication and bearing structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed preload systems are used in epicyclic traction transmissions, then the transmission structure is simple, but the torque density and mechanical efficiency are reduced due to excessive wear
Solution Approach 1:
The invention applies a variable preload system where the preload force dynamically adjusts with torque transmission. The preload mechanism includes a spring element that automatically increases preload as torque increases, optimizing the contact force between rolling elements and traction surfaces at all operating conditions, thereby preventing excessive wear while maintaining high mechanical efficiency
Solution Approach 2:
The invention changes the preload parameter from a fixed value to a variable value that depends on torque transmission. The preload force is made proportional to the transmitted torque through a mechanical linkage system, allowing the transmission to operate with optimal contact pressure across the entire torque range, thus improving reliability without excessive complexity
2Reliability
If variable preload systems are used to reduce wear, then mechanical efficiency improves, but alignment issues and mechanical play are introduced
Solution Approach 1:
The invention introduces a compliant intermediary element (spring-loaded mechanism) between the preload application point and the rolling elements. This intermediary absorbs misalignment and mechanical play while transmitting the variable preload force, maintaining both high mechanical efficiency and stable alignment throughout operation
Solution Approach 2:
The invention employs flexible elastic elements and compliant mechanisms in the preload system that can deform to accommodate minor misalignments while maintaining consistent contact force. This flexibility compensates for manufacturing tolerances and thermal expansion, preventing alignment issues while preserving the benefits of variable preload
3Volume of stationary object
If smaller radii of rolling components are used to achieve compact design, then volume is reduced, but contact stresses increase and fatigue life decreases
Solution Approach 1:
The invention changes the contact pressure parameter by implementing variable preload that optimizes the force distribution on rolling elements. By maintaining optimal contact pressure through torque-proportional preload, the system achieves high torque density in a compact volume while preventing excessive contact stresses that would reduce fatigue life
Solution Approach 2:
The invention applies dynamic preload adjustment that increases with torque transmission. This allows the compact transmission with small rolling elements to operate safely under varying loads, with the preload automatically scaling to prevent excessive contact stresses during high-torque operations, thereby extending fatigue life despite reduced component sizes
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 improves torque density and mechanical efficiency by allowing adjustable preload, reducing wear and mechanical play, thus extending the transmission's lifespan and improving operational performance.
Implementation Method 1
epicyclic traction transmission with frustoconical rolling elements... rolling contact elements... frustoconical rolling elements that allow axial preload application
Data Source
Figure 1~2
AI summary
Actuator comprising a solar roller (104), planetary rollers (102), auxiliary rollers (103) and a fixed crown (101), wherein the solar roller (104) is in the centre, the fixed crown (101) positioned externally to all the elements; the auxiliary rollers (103) are positioned between the planetary rollers (102) and the fixed crown (101) and the planetary rollers (102) make contact with the solar roller (104), the auxiliary rollers (103) and the fixed crown (101), characterised in that the solar roller (104), the planetary rollers (102), the auxiliary rollers (103) and the fixed crown (101) all have a frustoconical or truncated cone geometry. A transmission is achieved that provides a simple method of varying the preload on the rolling contact elements, thus providing a means of improving the torque density and mechanical efficiency of the transmission.