Self-Centering Double Cardan Joint Ball Socket Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing self-centering double cardan joints face issues with angular velocity fluctuations and component wear due to excessive bending angles, leading to vibration, noise, and early wear, and current designs for ball and socket associations in cardan shafts are difficult to manufacture and maintain, with challenges in achieving precise fits and preventing sharp edges.
Innovation Solution
A self-centering double cardan joint design featuring a ball with complete spherical geometry and opposed mounting recesses on the ball socket, allowing for concentric placement and rotation without lathing, which eliminates the need for precise diameter reduction and reduces friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ball is tightly placed into the cylindrical cavity with a socket insert, then the ball is constrained to rotate freely, but the tight fit causes increased friction and wear on the ball
Solution Approach 1:
The patent introduces a spherical seat as an intermediary component between the ball and the cylindrical cavity. The spherical seat has a spherical surface that contacts the ball, allowing the ball to rotate freely with reduced friction compared to direct contact with the cylindrical cavity. This mediator resolves the contradiction by providing both constraint stability and reduced wear.
Solution Approach 2:
The patent replaces the cylindrical cavity with a spherical cavity (spherical seat) to match the spherical geometry of the ball. This curvature matching allows the ball to rotate smoothly within the cavity with minimal friction and wear, while still maintaining proper constraint. The spherical geometry enables free rotation without the sliding friction inherent in cylindrical constraints.
2Ease of manufacture
If the ball diameter is reduced by lathing to fit the ball socket, then the ball can be installed, but sharp edges are formed on the ball surface
Solution Approach 1:
The patent removes the lathing operation entirely by designing the ball socket with a diameter larger than the ball diameter. This eliminates the need to machine the ball surface, thereby preventing the formation of sharp edges while still allowing proper installation. The extraction of the harmful machining step resolves the contradiction between ease of installation and surface quality.
Solution Approach 2:
Instead of reducing the ball diameter to fit the socket (traditional approach), the patent inverts the approach by making the socket larger than the ball. This reversal eliminates the need for diameter reduction machining while maintaining proper fit and installation ease, simultaneously preventing sharp edge formation.
3Manufacturing precision
If the ball and socket are machined with very precise tolerances, then the fit is ideal, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies partial constraint by making the ball socket diameter slightly larger than the ball diameter, rather than achieving a tight interference fit. This excessive clearance design provides ideal functional performance (free rotation with constraint) while significantly reducing machining precision requirements and manufacturing complexity.
Solution Approach 2:
The patent changes the dimensional parameter relationship between ball and socket from tight tolerance (near-equal diameters) to clearance fit (socket diameter > ball diameter). This parameter change maintains functional precision while dramatically reducing manufacturing complexity and tolerance stringency.
4Reliability
If the ball socket mouth diameter is smaller than the ball diameter, then the ball is prevented from coming off, but special processes are required to install the ball
Solution Approach 1:
The patent segments the ball socket into two functional zones: an upper mouth portion with diameter larger than the ball for easy installation, and a lower constraint portion with diameter smaller than the ball for retention. This segmentation allows the ball to be easily inserted through the large mouth while still being securely retained by the smaller lower portion, resolving the contradiction between retention and ease of installation.
Solution Approach 2:
The patent uses the vertical dimension of the ball socket to resolve the contradiction. The socket has a tapered or stepped geometry where the upper opening is larger than the ball diameter for easy installation, while the lower constraining portion has a smaller diameter for retention. This dimensional variation along the vertical axis allows both easy installation and secure retention without requiring special installation processes.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Centering ball (22) and a ball socket (21) for placement of said ball on self-centering double cardan joints, which is generally used in the cardan shafts transmitting the rotation motion and torque in the motor vehicles and enabling the axis of rotation to be changed, provides bending of two connection pieces of said joint with equal angle.