Slip Ball Joint Cage Geometry for Higher Torque Capacity
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Solution Overview
Problem
Ball constant velocity sliding joints with inclined ball tracks face issues where the ball tracks intersect, preventing force transmission and limiting torque capacity due to the constraints on cage window width and web thickness.
Innovation Solution
The design incorporates a cage with progressively decreasing gradient of center lines in the end regions, allowing for wider webs and potentially larger ball diameters to enhance stability and torque capacity without increasing packing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cage window width is increased to accommodate ball displacement, then the balls can perform displacement along the circumferential direction, but the web thickness decreases making the cage more susceptible to breakage
Solution Approach 1:
The cage windows are designed with variable cross-sectional areas along the axial direction, being larger in end regions to accommodate ball displacement and smaller in middle regions to maintain web strength. This dynamic variation in geometry allows the cage to adapt to different operational requirements at different locations.
Solution Approach 2:
Different sections of the cage have different structural characteristics: end regions have larger cage windows for ball displacement accommodation, while middle regions have smaller cage windows to maintain web integrity. This local differentiation optimizes both displacement capability and structural strength.
2Adaptability or versatility
If the ball track inclination angle is increased to enable axial displacement, then the joint can articulate, but the ball tracks intersect at large displacements preventing force transmission
Solution Approach 1:
The ball tracks are designed with variable inclination angles along the axial direction. The inclination angle is larger in end regions to facilitate ball displacement during articulation, and smaller in middle regions to prevent track intersection and maintain force transmission capability throughout the displacement range.
Solution Approach 2:
Different axial regions of the ball tracks have different inclination characteristics: end regions have steeper inclines for articulation movement, while middle regions have gentler inclines to avoid track crossing and ensure continuous torque transmission.
3Power
If the ball diameter is increased to transmit higher torque, then the torque capacity increases, but the packing size increases
Solution Approach 1:
The cage windows have varying cross-sectional areas along the axial direction, with larger areas at the ends accommodating ball displacement and smaller areas in the middle. This allows optimization of ball diameter for torque transmission while controlling the overall packing size through strategic placement of larger balls where needed.
Solution Approach 2:
Instead of uniformly increasing ball diameter throughout, the design varies the effective ball engagement geometry along the axial dimension, allowing high torque capacity where large balls are positioned while maintaining compact overall dimensions through the variable cage window configuration.
Data Source
AI summary
A ball constant velocity sliding joint, comprises an outer joint part with an axis of rotation and with outer ball tracks and outer center lines, an inner joint part with inner ball tracks and inner center lines, a plurality of torque-transmitting balls, which are each guided in outer ball tracks and inner ball tracks assigned to one another and forming track pairs; and a cage, which is provided with a plurality of cage windows, which each receive one or more of the balls; wherein the cage has a web along a circumferential direction between the cage windows, which web is guided via a respective spherical contact surface at least on the outer joint part or on the inner joint part.