Loading Cam Retainer Segmentation for Friction Roller Speed Reducer Stability
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Solution Overview
Problem
Conventional friction roller-type speed reducers face issues with retainer instability and reduced transmission efficiency due to excessive axial force and stress concentration, as well as durability concerns related to traction coefficient variations with peripheral speed.
Innovation Solution
The loading cam device incorporates a retainer with offset projections and concave portions on both axial surfaces, and a hydraulic chamber mechanism that adjusts axial pressing force based on centrifugal force and rotation speed, ensuring retainer stability and optimal traction coefficient adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the axial pressing force is increased to improve transmission efficiency, then the traction coefficient increases, but the retainer becomes unstable and experiences axial rattling
Solution Approach 1:
The retainer is segmented into multiple projection elements distributed around its circumference. Each projection independently engages with corresponding cam surfaces, distributing the axial pressing force across multiple contact points rather than concentrating it at a single location. This segmentation prevents retainer instability while maintaining effective transmission force.
Solution Approach 2:
The retainer features localized projection structures at specific circumferential positions that engage with cam surfaces. These localized engagement points create stable contact zones that prevent axial rattling while allowing the rest of the retainer structure to maintain flexibility. The local quality enhancement at projection tips provides precise force application without compromising overall stability.
2Power
If the pressing force is increased to improve power transmission, then the traction coefficient increases, but stress concentrates at specific points reducing durability
Solution Approach 1:
The pressing force is segmented into multiple discrete projection elements around the retainer circumference. Each projection carries a portion of the total load, preventing stress concentration at any single point. This distribution of stress across multiple engagement points enhances retainer durability while maintaining effective power transmission capability.
Solution Approach 2:
The retainer projection design incorporates rounded tips and gradual transition zones that cushion the impact of axial forces before they reach critical stress points. This beforehand cushioning through geometric design prevents sudden stress concentrations that would otherwise reduce durability during high-power transmission operations.
3Device complexity
If the retainer structure is simplified to reduce manufacturing complexity, then the device complexity decreases, but the retainer cannot maintain stability under varying axial forces
Solution Approach 1:
The retainer uses simple segmented projection elements that are easy to manufacture yet effective at maintaining stability. Each projection is a basic geometric feature that can be produced through standard machining processes, keeping manufacturing complexity low while the collective arrangement of multiple projections provides the necessary stability under varying axial forces.
Solution Approach 2:
The retainer combines multiple functional features into a single integrated structure. The projections serve dual purposes: they maintain retainer position stability and transmit axial forces to the cam surfaces. This merging of positioning and force transmission functions into one structure reduces overall device complexity while maintaining stability.
4Force
If the cam surface axial depth is increased to improve pressing force, then the traction coefficient increases, but the retainer experiences excessive stress and potential failure
Solution Approach 1:
The axial pressing force is segmented across multiple projection elements rather than applied through a single deep cam surface engagement. This allows the total required force to be achieved through distributed shallower engagements, reducing stress on any single retainer point while maintaining overall pressing effectiveness for optimal traction coefficient.
Solution Approach 2:
The design changes the engagement parameter from deep single-point contact to shallow multi-point contact. By increasing the number of contact points and decreasing individual engagement depth, the total pressing force remains effective for power transmission while stress distribution across multiple points prevents retainer failure.
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
This configuration prevents retainer axial rattling, enhances strength and stiffness, and improves transmission efficiency by dynamically adjusting the axial pressing force and traction coefficient in response to changing peripheral speeds.
Implementation Method 1
a hydraulic chamber mechanism that adjusts axial pressing force based on centrifugal force and rotation speed
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
On both axial direction surfaces of a cage, projections that protrude towards a cam plate and a disc are provided at multiple places in the circumferential direction, the phases of the projections in the circumferential direction being offset from various pockets. On one axial direction surface of the cam plate and the disc, recesses, the axial direction depths of which are deepest at the center in the circumferential direction and become shallower towards both ends, are provided at the areas facing each projection.