U-Shaped Shaft Seal Lip Geometry for Low-Torque Sealing
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Solution Overview
Problem
Existing shaft seals for scroll type compressors, such as those in in-vehicle air conditioners, face challenges in optimizing rotational torque and sealing performance due to unclear relationships between seal lip inclination, length, and torque, often resulting in high costs and inefficient sealing.
Innovation Solution
A shaft seal with a generally U-shape configuration, featuring a seal lip part that extends to the high-pressure side and an outer lip part, is designed with an inclined angle of 5-20 degrees relative to the rotational shaft and a length of 2.0-6.5 mm, formed from resin or thermoplastic elastomer compositions, including ETFE or PFA resin, to reduce rotational torque and enhance sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inclined angle of the seal lip is increased to improve sealing performance, then sealing performance is improved, but rotational torque increases
Solution Approach 1:
The patent optimizes the inclined angle parameter of the seal lip to a specific range (5-20 degrees) to achieve the best balance between sealing performance and rotational torque. This parameter optimization allows the seal lip to maintain effective contact with the rotating shaft for sealing while reducing the friction and torque required for rotation.
Solution Approach 2:
The seal lip length is optimized to a specific range (2.0-6.5 mm) to provide sufficient sealing contact without excessive length that would increase torque. This partial action approach ensures adequate sealing coverage while minimizing the rotational resistance.
2Reliability
If a metal core structure is used to enhance seal durability, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs composite material formulations (resin or thermoplastic elastomer compositions including ETFE or PFA resin) that provide enhanced durability and wear resistance without requiring a metal core structure. These composite materials offer a cost-effective alternative that maintains reliability while eliminating complex metal reinforcement.
Solution Approach 2:
The patent uses cost-effective resin or thermoplastic elastomer materials that, while potentially having shorter service life than metal, provide sufficient durability for the application at a significantly lower manufacturing cost, eliminating the need for expensive metal core structures.
3Reliability
If the seal lip length is increased to improve sealing performance, then sealing performance is improved, but rotational torque increases
Solution Approach 1:
The patent optimizes the seal lip length parameter to a specific range (2.0-6.5 mm) that provides sufficient sealing contact area for effective sealing performance while limiting the length to prevent excessive increase in rotational torque. This parameter optimization balances sealing effectiveness with energy efficiency.
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
This configuration effectively decreases rotational torque and improves sealing performance while offering superior cost efficiency by eliminating the need for metal cores and enhancing chemical and oil resistance, ensuring effective sealing in environments with refrigerants and oils.
Implementation Method 1
a seal lip part (2) that extends to the high-pressure side and is configured to slide on the rotational shaft (6)
Data Source
AI summary
A shaft seal having a ring shape adheres to an outer peripheral surface of a rotational shaft and thereby seals sealed fluid. The shaft seal partitions a gap between the rotational shaft and a housing to which the shaft seal is mounted, into a high-pressure side and a low-pressure side. The shaft seal is an injection-molded body having a generally U-shape in a sectional view about an axial direction. The shaft seal has a seal lip part that is configured to extend to the high-pressure side and slide on the rotational shaft, and an outer lip part that is disposed at an outer diametrical side relative to the seal lip part. An inclined angle of the seal lip part 2 relative to the outer peripheral surface of the rotational shaft is 5-20 degrees.