Radial Shaft Seal Recirculation Structure for Bidirectional Sealing
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Solution Overview
Problem
Existing radial shaft seals fail to provide effective sealing and recirculation of leakage oil at high rotational speeds and cannot operate efficiently in both rotational directions, leading to wear and leakage issues.
Innovation Solution
A radial shaft seal element with a support ring and a sealing portion featuring an annular projection and a recirculating structure, where the spacing between them varies to recirculate oil effectively in both rotational directions, using a metal or fiber-reinforced plastic material for the support ring and an elastomer or PTFE for the seal body, with a profile that ensures equal recirculating action in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard radial shaft sealing rings made of elastomers are used, then the seal can be simple in structure, but it cannot achieve the required tightness at high rotational speeds due to frictional heat damaging the seal material
Solution Approach 1:
The sealing lip is divided into multiple functional zones: a first sealing zone with a first sealing lip for primary sealing, and a second sealing zone with a second sealing lip for recirculation. This segmentation allows each zone to perform its specific function optimally, with the first zone providing tight sealing and the second zone managing leakage recirculation, thereby achieving required tightness at high rotational speeds
Solution Approach 2:
A recirculation channel is introduced as an intermediary structure between the sealing lip and the shaft. This channel receives leakage oil from the first sealing zone and guides it back to the oil side, creating a recirculation path that prevents direct contact between leakage oil and the environment, thereby maintaining sealing tightness without requiring excessive contact force
2Adaptability or versatility
If the seal is designed for one rotational direction, then it can optimize performance in that direction, but it cannot accept brief reversing movements with the same performance
Solution Approach 1:
The recirculation channel is designed with an asymmetric cross-sectional shape that is elongated in the circumferential direction. This asymmetric geometry creates different flow characteristics for forward and reverse rotation, allowing the channel to effectively recirculate leakage oil in both rotational directions while maintaining optimal sealing performance, thereby enabling bidirectional operation without sacrificing reliability
3Productivity
If spiral-shaped grooves or recirculating elements are provided on the sealing lip, then recirculation function is improved, but tightness problems occur in the static state depending on the material used
Solution Approach 1:
The sealing lip is segmented into a first sealing zone for primary sealing and a second sealing zone for recirculation. The first sealing zone maintains continuous contact with the shaft to ensure static tightness, while the second sealing zone contains the recirculation channel that is only activated during rotation. This segmentation allows recirculation elements to improve productivity without compromising static tightness
Solution Approach 2:
The recirculation channel is designed to be dynamically activated only during rotational operation. During static conditions, the first sealing lip maintains contact pressure for tight sealing. When rotation begins, the recirculation channel becomes active to handle leakage oil. This dynamic behavior allows the seal to optimize for recirculation efficiency during operation while maintaining static tightness when stationary
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 seal element effectively recirculates oil in both rotational directions, reducing leakage and wear, suitable for high-speed applications, and eliminates the need for separate seals based on rotational direction, thereby reducing storage and costs.
Implementation Method 1
the recirculating structure can run on a thin oil film on the shaft and thus can be lubricated. As a result, it can potentially lead to the ingress of oil (leakage oil) or liquid so that the leakage oil passes into the region between the annular projection and the recirculating structure
Data Source
AI summary
A radial shaft seal element includes a support ring and a seal body mounted on the support ring. The seal body includes a sealing portion configured to assume a cylindrical shape and bear against a shaft to be sealed and to separate an air side of the radial shaft seal from an oil side of the radial shaft seal. The seal body has a distal end at the oil side and an annular projection configured to bear against the shaft around a circumference of the shaft and a recirculating structure between the annular projection and the distal end. An axial spacing between the annular projection and the recirculating structure varies between a minimum and a maximum, and the recirculating structure has at least one gap that may be located at a region of the minimum spacing.