Rolling Cam Centering Structure for Low-Hysteresis Rotary Assemblies
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing centering structures generate hysteresis torque and suffer from durability issues due to friction slide and constant contact at a single point, leading to degradation in vibration attenuation and member durability.
Innovation Solution
A centering structure featuring outer and inner peripheral cam surfaces with rolling elements that reduce hysteresis torque and enhance durability by dispersing contact points and using rolling instead of friction slide, allowing for relative rotation within a predetermined angular range while preventing it outside that range, and incorporating a torque limiter and damper functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If friction slide contact is used between two members for centering, then the structure is simple, but hysteresis torque is generated and vibration attenuation performance degrades
Solution Approach 1:
The patent replaces the friction slide contact mechanism with a rolling contact mechanism using rolling elements (balls or rollers) between the first and second members. This substitution eliminates friction slide and hysteresis torque generation while maintaining the centering function, thereby improving vibration attenuation performance without significantly increasing structural complexity.
Solution Approach 2:
The patent introduces rolling elements as intermediary components between the first member's inner peripheral surface and the second member's outer peripheral surface. These rolling elements mediate the contact interaction, enabling centering through rolling motion rather than direct friction slide contact, thus resolving the contradiction between simplicity and vibration attenuation performance.
2Manufacturing precision
If two members make constant contact at the same part for centering, then centering accuracy is maintained, but abrasion of the contact part progresses and durability degrades
Solution Approach 1:
The patent segments the contact interface by distributing multiple rolling elements around the circumference between the first and second members. This segmentation divides the centering function across multiple contact points rather than concentrating it at a single location, preventing localized abrasion and improving durability while maintaining centering accuracy through the collective action of all rolling elements.
Solution Approach 2:
The patent enables dynamic rotation of the rolling elements relative to the contact surfaces. As the second member rotates within the predetermined angular range, different portions of the outer peripheral surface contact different rolling elements, distributing wear across multiple contact points over time. This dynamic contact pattern prevents progressive abrasion at a single location while maintaining accurate centering.
3Reliability
If rolling elements are used instead of friction slide contact, then hysteresis torque is reduced and durability is enhanced, but device complexity increases
Solution Approach 1:
The patent designs the rolling elements and their supporting structures to perform multiple functions simultaneously: providing centering through rolling contact, accommodating relative rotation within a predetermined angular range, limiting torque transmission, and dampening vibrations. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving improved reliability and durability.
Solution Approach 2:
The patent merges the centering function with torque limiting and vibration damping functions into a single integrated structure using rolling elements. The accommodation spaces and cam surfaces are designed to combine these functions, eliminating the need for separate centering mechanisms, torque limiters, and dampers, thus minimizing the increase in device complexity while achieving enhanced 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 reduces hysteresis torque, enhances durability, and allows for accurate centering with lower manufacturing precision, while functioning as a torque limiter and damper, improving the overall performance of the centering mechanism.
Implementation Method 1
The plurality of rolling elements are disposed in the plurality of accommodation spaces. Each of the plurality of rolling elements is capable of rolling along each of the plurality of outer peripheral cam surfaces and each of the plurality of inner peripheral cam surfaces.
Implementation Method 2
Hence, friction slide occurs at the contact part of the two members. A hysteresis torque is generated between the two members by the friction slide.
Data Source
AI summary
A centering structure is provided in a device including a first member with an inner peripheral surface and a second member with an outer peripheral surface opposed to the inner peripheral surface. The centering structure includes outer peripheral cam surfaces circumferentially aligned on the inner peripheral surface of the first member, inner peripheral cam surfaces opposed to the outer peripheral cam surfaces, and rolling elements. The inner peripheral cam surfaces form accommodation spaces together with the outer peripheral cam surfaces therebetween. The rolling elements are disposed in the accommodation spaces. Each rolling element rolls along each outer peripheral cam surface and each inner peripheral cam surface. The rolling elements move the first or second member in a direction to cause a center of the inner peripheral surface and a center of the outer peripheral surface to be matched when the first and second members are rotated relative to each other.