Propeller Shaft CV Joint Cage Offset for Size and Weight Reduction
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Solution Overview
Problem
Existing plunging type constant velocity universal joints for propeller shafts face challenges in achieving size reduction and weight reduction while maintaining performance, especially in meeting demands for improved fuel efficiency and increased rotation speed.
Innovation Solution
The design of a plunging type constant velocity universal joint dedicated to propeller shafts, featuring a reduced maximum operating angle of 15° or less, optimized component dimensions, and a cage with reduced offset, to achieve size and weight reduction while maintaining torque transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the maximum operating angle of the DOJ is limited to a low value (15° or less) for propeller shaft applications, then radial size and weight can be reduced by reducing wall thickness of components, but the versatility and adaptability of the joint are reduced
Solution Approach 1:
The patent applies local quality by optimizing specific geometric parameters (offset ratio f/PCDBALL between 0.05-0.10, track groove angles, pocket positions) for the specific application condition of small operating angles, rather than designing for a wide range of angles. This localized optimization enables weight reduction while maintaining performance for propeller shaft applications.
Solution Approach 2:
The patent changes key geometric parameters from conventional values: reduces offset ratio to 0.05-0.10 (conventionally higher), reduces wall thickness of outer joint member, inner joint member, and cage, and optimizes track groove angles. These parameter changes enable size and weight reduction specifically for small operating angle applications.
2Volume of moving object
If the offset of the cage is reduced to achieve further size and weight reduction, then the technical effects of size reduction are enhanced, but the structural strength and load-bearing capacity may be compromised
Solution Approach 1:
The patent employs composite material construction for the cage, combining materials with different properties to achieve both reduced offset (for compactness) and maintained strength. The outer joint member, inner joint member, and cage use optimized material compositions that provide high strength-to-weight ratio, enabling the reduced offset design (f/PCDBALL: 0.05-0.10) to maintain structural integrity.
Solution Approach 2:
The patent utilizes spherical geometry for the cage structure and ball contacts, where the curved surfaces distribute loads more evenly across the contact areas. This spherical design allows for reduced offset while maintaining strength, as the curved geometry naturally handles stress concentrations better than sharp corners or flat surfaces.
3Reliability
If axial pocket clearance and axial clearance are provided to improve life and reduce sliding resistance, then durability and rotation speed capability are improved, but device complexity increases
Solution Approach 1:
The patent incorporates preliminary action by pre-establishing specific clearance values during manufacturing: axial pocket clearance δ1 between 0-0.050mm and axial clearance δ2 between 0.5-1.5mm. These clearances are built into the design from the start, allowing the joint to accommodate thermal expansion, manufacturing tolerances, and wear, thereby extending service life and enabling higher rotation speeds without requiring complex adjustment mechanisms.
Data Source
AI summary
A plunging type constant velocity universal joint 1 for a propeller shaft includes an outer joint member 2, an inner joint member 3, eight torque transmidetting balls 4, and a cage 5. A center of curvature O1 of a spherical outer surface 12 and a center of curvature O2 of a spherical inner surface 13 of the cage 5 each have an equal and axially opposite offset (f) with respect to a center O3 of pockets 5a. A ratio f/PCDBALL between the offset (f) of the cage 5 and a pitch circle diameter (PCDBALL) of the torque transmitting balls 4 is 0.07 or more and 0.09 or less.