Cross Groove Joint Cage Web Strength via Skew Angles
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Solution Overview
Problem
Conventional cross groove joints with higher numbers of balls, such as eight-ball types, face challenges in maintaining durability and strength due to increased stress on the cage web, leading to potential ball locking issues and reduced load-bearing capacity compared to six-ball joints.
Innovation Solution
The cross groove joint design incorporates optimized skew angles and groove shapes, with different configurations for different groups of ball grooves, including linear and skewed grooves, to enhance the mechanical strength and durability of the cage web while minimizing ball locking risks, by using a combination of taper angles and varying skew angles to accommodate more balls without compromising strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the number of balls is increased from six to eight to make the joint more compact, then the ball diameter can be reduced and load per ball decreases, but the cage web thickness must be reduced to accommodate more cage windows, causing increased stress on the cage web and reduced durability
Solution Approach 1:
The patent applies different skew angles to different groups of ball grooves. Specifically, grooves in the 12 o'clock and 6 o'clock positions have one skew angle, while grooves at other positions have different skew angles. This local differentiation allows optimization of ball movement paths in critical areas, reducing the required cage window size and preserving cage web thickness and strength.
Solution Approach 2:
The patent changes the skew angle parameter across different groove positions rather than using a uniform skew angle. By adjusting the skew angle parameter locally, the design accommodates ball movement requirements while minimizing cage window dimensions, thereby maintaining cage web strength despite the increased number of balls.
2Adaptability or versatility
If the skew angle of ball grooves is increased to accommodate ball movement, then the joint can handle larger articulation angles, but the cage window size must be enlarged, reducing the cage web thickness and increasing stress on the cage web
Solution Approach 1:
The patent implements local quality by assigning different skew angles to different groove groups based on their positional requirements. Grooves at 12 o'clock and 6 o'clock positions have different skew angles compared to other grooves, optimizing ball movement for each location while minimizing overall cage window dimensions.
Solution Approach 2:
The patent segments the ball grooves into different groups with different skew angle characteristics. This segmentation allows each group to be optimized independently for its specific functional requirements, reducing the need for uniformly large cage windows and preserving cage web strength.
3Device complexity
If uniform skew angles are used for all ball grooves, then the design is simpler, but ball locking issues occur at certain articulation angles when grooves align
Solution Approach 1:
The patent introduces asymmetry by using different skew angles for different groups of ball grooves. This asymmetric configuration prevents all grooves from aligning simultaneously at any articulation angle, thereby eliminating the ball locking phenomenon that occurs with uniform skew angles.
Solution Approach 2:
By applying different skew angles to different groove positions, the patent creates local variations that prevent synchronous alignment of all grooves. This local differentiation ensures reliable operation across the full range of articulation angles without ball locking issues.
Data Source
AI summary
A constant velocity joint for a drive system comprises an outer joint member and an inner joint member each having a plurality of ball grooves in pairs for accommodating balls therein, the ball grooves consisting of a first group of grooves, each groove of which having a linear groove shape with no skew angle or a skewed groove shape with a relatively smaller skew angle, and a second group of grooves, each groove of which having a skewed groove shape with a relatively larger or regular skew angle. In addition to having the differentiated skew angles in the first and second groups of grooves, a taper angle is provided to the pair of grooves of at least one or both of the first and second groups of grooves in order to reduce the potential risk of ball locking in the grooves. In an alternative embodiment, all the grooves of the outer and inner joint members have a skewed groove shape with a skew angle which is less than the regular skew angle of the conventional cross groove joint, and a taper angle is provided to the pairs of grooves of the outer and inner joint members.