Dual-Ring Radial Shaft Seal for High-Speed Bidirectional Sealing
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Solution Overview
Problem
Radial shaft seals fail to provide reliable sealing at high rotational speeds and circumferential speeds due to the inefficiency of slanted ribs as return elements, which are not suited for reliable medium return at speeds above 10,000 rpm and 25 m/s.
Innovation Solution
The addition of second return elements on the air side of the second ring, which are slanted and positioned to ensure efficient medium return to the medium side, combined with the first return elements, enhances the radial shaft seal's return efficiency and prevents vacuum generation, allowing for effective sealing at high speeds and alternating rotational directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If slanted ribs are used as return elements, then the seal works at low to medium rotational speeds, but the return efficiency deteriorates at high rotational speeds above 10,000 rpm
Solution Approach 1:
The return elements are segmented into two distinct circumferential rings: a first ring with first return elements and a second ring with second return elements. Each ring handles medium return for a specific rotational direction, ensuring reliable sealing performance across high-speed operations in both forward and reverse directions.
Solution Approach 2:
The first return elements and second return elements are configured with asymmetric orientations relative to the circumferential direction. The first return elements are slanted in one direction while the second return elements are slanted in the opposite direction, optimizing medium return efficiency for respective rotational directions at high speeds.
2Device complexity
If single ring with return elements is used, then the structure remains simple, but vacuum generation occurs reducing pump action at high speeds
Solution Approach 1:
The seal structure is divided into two functional rings: the first circumferential ring handles medium return in one rotational direction, while the second circumferential ring handles medium return in the opposite rotational direction. This segmentation prevents vacuum generation by providing dedicated return paths for each direction, maintaining pump action at high speeds.
Solution Approach 2:
The dual-ring configuration with differently oriented return elements enables the seal to universally handle medium return for both forward and reverse rotational directions. Each ring serves as a specialized return path, ensuring consistent pump action and preventing vacuum effects regardless of rotation direction.
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 enhanced radial shaft seal achieves high return efficiency and pump action, ensuring proper sealing between the medium and air sides, even at rotational speeds up to 50,000 rpm, making it suitable for electric motors in the automotive industry, particularly in electromobility applications.
Implementation Method 1
the return elements are provided at the side of the first ring facing the air side and convey leakage medium to the medium side independent of the rotational direction of the shaft
Implementation Method 2
The return efficiency as well as the pump action of the radial shaft seal is therefore raised to a very high level
Data Source
AI summary
A radial shaft seal for a shaft to be sealed operating at high rotational speeds and circumferential speeds in both rotational directions has a sealing lip with a first circumferential ring and a second circumferential ring. The first circumferential ring is resting seal-tightly against the shaft to be sealed and seals the medium side. At the side of the first circumferential ring facing the air side, there are first return elements that convey leakage medium back to the medium side. The second circumferential ring is provided at the side of the first circumferential ring facing the air side and second return elements are provided at its air side. The second return elements guide medium that has passed underneath the second circumferential ring back underneath the second circumferential ring to the medium side.