Spring-Ball Positioning via Slit Flexibility and Keyed Flanges
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Solution Overview
Problem
Existing spherical plain bearing configurations, such as those disclosed in European Patent Specification No. EP 2,986,862 B1, require an improved method to maintain axial and circumferential position of the spring-ball on a shaft while allowing for radial expansion and contraction to compensate for wear and maintain constant operating torque.
Innovation Solution
A ball and shaft arrangement featuring a spring-ball with a slit for radial flexibility, a circumferential movement limiter (key) to prevent rotation, and an axial movement limiter system comprising flanges on the shaft to limit axial movement, with keyways and flanges aligned to secure the spring-ball in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a spring-ball configuration is used to allow radial expansion and contraction to compensate for wear, then the bearing can maintain constant operating torque, but the axial and circumferential position of the spring-ball on the shaft becomes difficult to control
Solution Approach 1:
The position control system is segmented into two independent subsystems: a circumferential movement limiter (key-way structure) that prevents rotation, and an axial movement limiter system (flanges) that prevents axial displacement. This segmentation allows each subsystem to specialize in one direction of constraint while the spring-ball maintains radial flexibility for wear compensation.
Solution Approach 2:
Different parts of the spring-ball and shaft assembly have different mechanical properties: the spring-ball material provides radial elasticity for wear compensation, while the key-way and flange structures provide rigid constraints in axial and circumferential directions. This local differentiation of mechanical properties resolves the contradiction between radial adaptability and positional stability.
2Duration of action of stationary object
If the spring-ball is allowed to radially flex to compensate for wear, then operating torque remains constant, but the spring-ball may rotate or shift axially on the shaft
Solution Approach 1:
The key is installed in the key-way structure before the spring-ball is fully assembled onto the shaft. This preliminary action ensures that the circumferential constraint is already in place, preventing rotation during the subsequent assembly and operation phases, while the flanges are positioned to prevent axial movement.
Solution Approach 2:
The key-way structure acts as an intermediary element between the spring-ball and the shaft, providing a mechanical interface that prevents circumferential rotation while allowing the spring-ball to maintain its radial flexibility for wear compensation over the bearing's service life.
3Reliability
If a complex retention system is used to maintain spring-ball position, then axial and circumferential stability is improved, but the device complexity increases
Solution Approach 1:
The axial and circumferential constraint functions are merged into a single integrated key-way structure that combines the key (for circumferential constraint) and the flanges (for axial constraint). This merging reduces the number of separate components compared to using independent retention mechanisms for each direction, thereby reducing overall device complexity while maintaining position stability.
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 maintains the axial and circumferential position of the spring-ball relative to the shaft, allowing for radial expansion and contraction while preventing unwanted movement, thus ensuring consistent torque and extended bearing performance.
Implementation Method 1
The slit is configured to allow the spring-ball to radially flex
Data Source
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AI summary
A ball and shaft arrangement for a spherical bearing (10) includes a spring-ball (12) having a spherical exterior surface (12E) and an interior area (13) defined by an inner surface (14) extending between a first axial end (12A) and a second axial end (12B) thereof. The inner surface (14) defines a first inside diameter (D1) and a slit (15) extending through the spring-ball (12) from the first axial end (12A) to the second axial end (12B). The slit (15) is configured to allow the spring-ball (12) to radially flex. The shaft (20) has a ball receiving surface (22) formed thereon and is disposed partially in the interior area (13) of the spring-ball (12). A circumferential movement limiter is in communication with the spring-ball (12) and the shaft (20) and is configured to prevent circumferential rotation of the spring-ball (12) relative to the shaft (20). An axial movement limiter system is formed in portions of the spring-ball (12) and the shaft (20) and is separate from the circumferential movement limiter. The axial movement limiter system is configured to limit axial movement of the spring-ball (12) relative to the shaft (20).