CV Joint Assembly With Offset Ball Spline and Separate Boots
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Solution Overview
Problem
Existing constant velocity stroking joints, such as the Rzeppa-type joint, are limited in angulation and stroking movement due to complex component designs and require excessive grease, leading to inefficiencies and size constraints in automotive applications.
Innovation Solution
A constant velocity joint assembly featuring an inner and outer annulus with a ball spline axially offset from the pivot axis, allowing decoupled angulation and axial stroking movements, and utilizing flexible boots for sealing and independent flexing to minimize size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single boot cover is used to accommodate both angulation and stroking movement, then the joint can provide combined movement capabilities, but the joint is limited to about 25 degrees of angulation and requires a relatively large amount of grease
Solution Approach 1:
The joint is divided into two separate functional sections: a Rzeppa constant velocity joint section for angulation movement with its own boot cover, and a stroking joint section for axial movement with its own boot cover. This segmentation allows each section to be optimized independently, eliminating the 25-degree angulation limit imposed by single-boot designs and reducing grease requirements for each section.
2Adaptability or versatility
If the ball spline is radially aligned with the pivot axis, then the joint can accommodate both movements, but the ball circle diameter of the ball splines must be larger than that of the Rzeppa balls, increasing joint size
Solution Approach 1:
The ball spline is repositioned from radial alignment with the pivot axis to axial alignment along the pivot axis. This dimensional change in the ball spline's position allows the ball circle diameter of the ball splines to be equal to or less than that of the Rzeppa balls, reducing joint size while maintaining both angulation and stroking movement capabilities.
3Ease of operation
If radially aligned ball splines are used, then axial stroking movement is supported, but excessive grease is required to lubricate both the Rzeppa portion and the stroking portion
Solution Approach 1:
The lubrication system is segmented into two separate boot-covered sections, each containing its own lubricant. The Rzeppa CV joint section contains grease for lubricating the constant velocity balls, while the stroking joint section contains grease for lubricating the ball splines. This segmentation eliminates the need for excessive grease quantity in a single combined section.
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 enables improved angulation and axial movement capabilities while reducing the size and weight of the joint, minimizing grease requirements and simplifying the design for enhanced performance and efficiency.
Implementation Method 1
A ball spline is disposed between the third race and the fourth race for axial stroking movement of the third race relative to the fourth race
Implementation Method 2
utilizing flexible boots for sealing and independent flexing
Data Source
AI summary
A constant velocity joint assembly includes an inner annulus having a first race and an outer annulus having a second race supporting the first race for pivotal movement relative to the second race about a pivot axis. A third race is provided by the outer annulus and a fourth race is provided by an interface member. A ball spline is disposed between the third race and the fourth race for axial stroking movement of the third race relative to the fourth race, wherein the ball spline is axially offset from the pivot axis. Separate boots seal and isolate the pivotal movement and the stroking movement from one another.