Constant Velocity Ball Joint Cage Windows for Low-Pressure Contact
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Solution Overview
Problem
Constant velocity ball joints face challenges with a low degree of contact between torque-transmitting balls, especially when bent, leading to increased contact pressure and a higher risk of material failure, which existing solutions attempt to address with limited success through offset corrections or track form adaptations that are detrimental to structural volume.
Innovation Solution
The design incorporates three types of track pairs with varying opening angles and a multiple-ball cage window configuration, where at least one ball from each type is accommodated together, reducing friction and structural volume while maintaining mechanical stability by guiding balls along outer and inner center lines that intersect at a common joint center plane, even when bent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If offset correction or track form adaptation is applied to increase the degree of contact, then the contact pressure is reduced, but the structural volume increases
Solution Approach 1:
The ball cage is segmented into multiple cage windows, with each window accommodating specific balls (first, second, and third balls) associated with different track pairs. This segmentation allows optimized contact geometry for each ball without increasing overall structural volume, as each window is precisely shaped to guide its associated balls along the desired center lines.
Solution Approach 2:
Different cage windows are designed with different local geometries to accommodate balls in different track pairs with different opening angles. The first cage window is configured for balls in track pairs with opening angles opening toward the first attaching end, the second cage window for balls in track pairs with opening angles opening toward the aperture end, and the third cage window for balls in track pairs with smaller opening angles. This local differentiation optimizes contact for each position without requiring uniform volume increase throughout the structure.
2Reliability
If the joint is bent, then the degree of contact decreases and contact pressure increases, but the structural configuration remains fixed
Solution Approach 1:
The ball cage is designed to dynamically adapt to joint bending through its multiple cage window configuration. When the joint bends, the balls are guided along center lines that intersect at the joint center plane, and the cage windows maintain proper ball alignment despite the changing geometry. This dynamic guidance system ensures that balls remain in optimal contact positions throughout the bending range, preventing contact pressure spikes that would occur in fixed-geometry designs.
3Productivity
If counter track joint configuration is used to balance axial forces, then friction is reduced and efficiency increases, but the degree of contact becomes small
Solution Approach 1:
The invention merges the benefits of counter track joints (balanced axial forces, low friction) with enhanced contact geometry through the multiple-ball cage window configuration. Balls in adjacent cage windows work together to maintain both force balance and adequate contact. The first, second, and third balls in each cage window are positioned to simultaneously achieve the force-balancing effect of counter tracks and the high contact degree achieved through optimized cage window geometries that guide all three balls along intersecting center lines.
Data Source
AI summary
A constant velocity joint includes an outer joint portion with a first longitudinal axis, a first attaching end, an aperture end and outer ball tracks on an inner circumferential surface, an inner joint portion with a second longitudinal axis, a second attaching end, an inner face facing towards the outer joint portion and inner ball tracks on its outer circumferential surface, balls for torque transmission between the outer and inner joint portions, an annular ball cage between the outer and inner joint portions with several cage windows in which the balls are guided. The inner and outer joint portions are arranged so that one outer ball track and one inner ball track are in each case arranged opposite to each other to form three different types of track pairs to receive one respective balls. The balls have different controlling behaviors due to different track geometries.