CV Joint Boot Ventilation Groove Pressure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Constant velocity universal joints experience increased internal pressure and reduced boot life due to heat generation during high-speed rotation, leading to lubricant leakage and compromised sealing properties.
Innovation Solution
A boot design featuring a lip portion on the inner peripheral surface of the end portion abutting the shaft and a ventilation groove on the inner peripheral surface, which controls internal pressure and prevents lubricant leakage through strategic placement and phase shifting of ventilation holes and grooves, along with a porous member to enhance sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the boot is sealed to prevent lubricant leakage, then sealing property is improved, but internal pressure increases due to heat generation during high-speed rotation
Solution Approach 1:
The boot incorporates a porous layer in its structure, allowing it to function as both a seal and a pressure relief mechanism. The porous structure permits controlled passage of lubricant and heat while maintaining overall sealing integrity, thus resolving the contradiction between preventing leakage and managing internal pressure during high-speed operation
2Reliability
If the boot is tightly sealed to prevent lubricant leakage, then sealing property is improved, but boot life is reduced due to heat generation
Solution Approach 1:
The porous layer in the boot structure enables heat dissipation while maintaining sealing functionality. This allows the boot to withstand high-speed rotation and heat generation for extended periods without degradation, thereby extending boot life while preserving sealing property
3Stress or pressure
If ventilation holes are added to reduce internal pressure, then internal pressure control is improved, but lubricant may leak through the ventilation holes
Solution Approach 1:
The porous layer acts as a selective filter that allows pressure equalization while blocking lubricant leakage. The pore structure and surface tension effects prevent lubricant from passing through while permitting air flow for pressure relief, thus resolving the contradiction between pressure control and lubricant retention
4Quantity of substance
If the lip portion is positioned close to the outer joint member to reduce lubricant volume, then cost is reduced, but sealing effectiveness may be compromised
Solution Approach 1:
The porous layer in the boot structure enhances sealing effectiveness at the lip portion by creating capillary action and surface tension barriers. This allows the lip to be positioned closer to the outer joint member, reducing lubricant volume and cost, while the porous structure maintains sealing effectiveness through controlled fluid 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 solution effectively prevents lubricant leakage, reduces internal pressure, and extends boot life by ensuring a satisfactory sealing property and heat radiating action, resulting in a high-reliability and long-lasting constant velocity universal joint.
Implementation Method 1
heat generation at the time of high-speed rotation of the propeller shaft
Implementation Method 2
control an increase in internal pressure of the joint due to heat generation
Implementation Method 3
the lip portion abutting on an outer peripheral surface of the shaft is provided on an inner peripheral surface of the small diameter end portion
Implementation Method 4
a porous member to enhance sealing
Data Source
Figure 1
Figure 2
Figure 3A~3D
AI summary
Disclosed is a constant velocity universal joint, comprising: an outer joint member (10) in which at least one end portion is open; an inner joint member (20) for transmitting torque together with the outer joint member (10) through balls (30) under a state in which angular displacement is allowed; a boot (70) for closing an opening portion of the outer joint member (10), the boot (70) having a small diameter end portion (72) fitted onto a shaft (50) extending from the inner joint member (20) ; a lip portion (75) abutting on an outer peripheral surface of the shaft (50) ; and a ventilation groove (76) for establishing communication between an inside and an outside of the boot (70), the lip portion (75) and the ventilation groove (76) being formed in an inner peripheral surface of the small diameter end portion (72) of the boot (70).