Propeller Shaft CV Joint Assembly for Boot Inversion Resistance
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Solution Overview
Problem
Propeller shafts with cross groove constant velocity joints face issues with uneven axial load distribution and radial inversion of boots due to centrifugal forces and grease load, leading to reduced durability, especially under high-speed and high-temperature conditions.
Innovation Solution
A propeller shaft design incorporating two cross groove constant velocity joints connected by a connecting shaft, with a grease cover and a boot that resists radial inversion, featuring a cage with windows larger than the balls to maintain alignment and a spring mechanism to reduce axial loads and noise, ensuring even load distribution and increased durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a boot is used to enclose the constant velocity joint, then protection from dirt, debris and moisture is provided, but radial inversion occurs under high-speed and high-temperature conditions due to centrifugal forces and grease load
Solution Approach 1:
The patent applies preliminary anti-action by providing a grease cover that prevents grease from leaking onto the boot before the centrifugal forces can cause radial inversion. The grease cover acts as a preventive measure, blocking the source of the problem (grease load) before it can combine with centrifugal forces to invert the boot and reduce durability.
2Adaptability or versatility
If cross groove joints are used to permit axial movement, then adaptability to angular and axial displacement is improved, but uneven distribution of axial loads increases and durability decreases
Solution Approach 1:
The patent introduces an intermediary element - a spring mechanism positioned between the inner and outer races of the constant velocity joint. This spring acts as a mediator that distributes axial loads more evenly across the joint components, preventing the uneven load distribution that occurs in conventional cross groove joints while maintaining their axial movement capability.
3Stability of the object's composition
If the cage windows have dimensions larger than the balls, then alignment and retention of balls is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by making the cage window dimensions locally larger than the ball diameter in specific regions. This localized dimensional increase provides sufficient clearance for ball alignment and retention without requiring the entire cage structure to be more complex. The windows are strategically designed with increased dimensions only where needed for ball interaction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively prevents radial inversion and enhances the durability of the propeller shaft by maintaining center alignment of the joints, reducing noise and vibration, and distributing axial loads evenly, thereby improving the shaft's performance under high-speed and high-temperature conditions.
Implementation Method 1
a spring mechanism to reduce axial loads and noise
Implementation Method 2
reducing noise and vibration
Implementation Method 3
radial inversion of the boot is effected by the geometry of the first peak and valley of the convolutions because the boot typically has the largest swing diameter in this region. A larger swing diameter tends to create a higher degree of radial inversion.
Data Source
AI summary
A propeller shaft including a first shaft, a first constant velocity joint drivingly connected with the first shaft, a second shaft, a second constant velocity joint drivingly connected with the second shaft, a connecting shaft drivingly connecting the first constant velocity joint and the second constant velocity joint and a grease cover disposed about an axial end of the second constant velocity joint. The second constant velocity joint is provided with a spring mechanism including a spring, wherein a spring seat of the spring mechanism is positioned on one axial end of the spring and mates with the second shaft, and wherein another axial end of the spring mates with an additional spring seat that is formed in the grease cover of the second constant velocity joint. The second constant velocity joint further comprises a spacer positioned between the spring and the grease cover and attached to the grease cover, wherein the spring has an axial end portion and a reduced diameter portion, and wherein an outer diameter of the reduced diameter portion is less than an outer diameter of the axial end portion.