Constant Velocity Joint Cage with Shorter Windows
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Solution Overview
Problem
Constant velocity fixed joints used in drive shafts face a decrease in breaking strength at large bending angles due to uneven force distribution on balls and increased loads on the cage, limiting their application and fatigue life, especially when the cage wall thickness and window design compromise load-bearing capacity and assembly requirements.
Innovation Solution
The design features shorter cage windows in the circumferential direction with stronger webs, achieved by providing alternative ball paths outside the standard raceway locations, allowing balls to escape radially and circumferentially during assembly, thus reducing window length and increasing web strength, and allowing for larger bending angles without compromising assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cage wall thickness is increased to strengthen the cage, then the breaking strength increases, but the ball wrap in the ball raceways decreases and load-bearing capacity drops
Solution Approach 1:
The invention changes the geometric parameters of the cage windows, specifically making them shorter in the circumferential direction. This allows the cage walls to be thinner while maintaining structural integrity, because the shorter window spans reduce the bending moments and stresses in the cage walls. Consequently, the ball wrap is improved without compromising cage strength.
2Adaptability or versatility
If the cage windows are made longer to accommodate ball displacement at large bending angles, then the joint can operate at larger deflection angles, but the webs between windows become weaker and breaking strength decreases
Solution Approach 1:
The invention optimizes the window length parameter to a specific value that simultaneously satisfies both requirements: it is long enough to accommodate the ball displacement at large bending angles (enabling operation at deflection angles greater than 40°), but short enough to maintain adequate web strength and breaking strength.
3Strength
If smaller balls are used to reduce window length and increase web strength, then the breaking strength improves, but the service life of the joint decreases
Solution Approach 1:
The invention changes the window length parameter independently of ball size. By optimizing the window length to a specific value, the design allows using larger balls (which improve service life) while still maintaining adequate web strength and breaking strength, thus resolving the contradiction between strength and durability.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a constant velocity fixed joint comprising an outer joint part (2) having a plurality of ball bearing races (4) on the inner circumference, an inner joint part (3) having a plurality of ball bearing races (5) on the outer circumference, a cage (10) having a plurality of windows (13) disposed between the outer joint part (2) and the inner joint part (3), and ball bearings (6) each disposed in a window (13) of the cage (10) and engaging with the ball bearing races (4, 5) of the outer joint part (2) and the inner joint part (3) for transmitting torque. Recesses (15) adjoin the ball bearing races (4, 5) of the outer joint part (2) and/or the inner joint part (3), and are expanded radially and/or in the circumferential direction relative to the ball bearing races (4, 5) of the outer joint part (2) or the inner joint part (3), in order to enable deflection of the affected ball bearings (6) relative to an imaginary extension of the ball bearing races (4, 5) in the radial direction and/or the circumferential direction when the joint is excessively bent into a position for installing the ball bearings. The fracture strength of a constant velocity fixed joint designed for large operating bend angles can hereby be considerably increased. The installation of the ball bearings (6) is also simplified.