Radial Shaft Seal Geometry for Low-Friction Leak Control
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Solution Overview
Problem
Existing radial shaft seals for rotating shafts in coolant pumps with low-viscosity, water-based coolants suffer from high friction and leakage losses, premature wear, and reduced sealing effectiveness due to temperature variations, leading to thermal damage and leaks, especially at high speeds, and require complex and costly manufacturing processes.
Innovation Solution
A radial shaft seal design featuring an elastomeric sealing member and a PTFE sealing member with a metallic bracing system, including a frustoconically inclined sealing-member contact flange and a bracing-member web with a substance-to-substance bond, minimizes wear and friction through optimized contact geometry and secure positioning, using inexpensive stamped parts and a cord spring for optimal prestressing and vibration damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If cord springs are used to press the sealing lips against the running sleeve, then leakage losses are minimized, but friction losses and power losses increase
Solution Approach 1:
The patent changes the pressing mechanism from elastic cord springs to a geometric solution using the frustoconically inclined sealing-member contact flange. The inclination angle creates a mechanical advantage that generates sealing force through the prestressing of the elastomeric sealing member, eliminating the need for continuous elastic pressure while maintaining effective sealing.
Solution Approach 2:
The invention extracts and removes the cord spring component from the sealing system. By eliminating this elastic element, the design avoids the continuous friction and energy loss associated with spring-loaded sealing lips, while achieving sealing through the geometric configuration of the contact flange.
2Reliability
If lathe-turned metallic bracing members are used to position sealing members, then positional securing is achieved, but fabrication expenditure increases
Solution Approach 1:
The patent replaces solid lathe-turned metallic bracing members with thin-walled stamped metallic components. These stamped parts achieve the necessary positional securing and structural support through their formed geometry and interference fit installation, significantly reducing manufacturing complexity and cost compared to traditional lathe-turned components.
Solution Approach 2:
The invention changes the manufacturing method from precision lathe-turning to stamping processes. This parameter change in fabrication technique reduces tooling requirements, production time, and expenditure while maintaining the functional integrity and positional accuracy of the bracing members through precise stamping geometry.
3Reliability
If high assembly forces are applied during assembly, then reliable radial positional securing is achieved, but damage to elastomeric sealing member occurs
Solution Approach 1:
The patent introduces the cord spring as a dynamic, elastic element that provides continuous radial prestressing force to the sealing lips. This dynamic mechanism maintains reliable sealing pressure during operation without requiring excessive assembly forces, as the spring gradually establishes its prestressing force after installation, thereby protecting the elastomeric sealing member from damage.
4Loss of substance
If full-surface contact sealing cylinders are used, then leakage prevention is improved, but friction losses increase
Solution Approach 1:
The patent applies partial action by using the cord spring to press the sealing lips with sufficient force to achieve effective sealing, rather than excessive full-surface contact pressure. The elastic prestressing provides just enough contact pressure to prevent leakage while minimizing friction, avoiding the energy losses associated with overly aggressive full-surface sealing contact.
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 significantly reduces friction and leakage losses, enhances reliability and lifespan, prevents leaks while stationary, and allows for 'air-free' vacuum filling even after prolonged service, while simplifying manufacturing and assembly, thus reducing costs.
Implementation Method 1
a cord spring is disposed that presses the sealing cylinder together with the associated sealing lip against the running sleeve
Implementation Method 2
power losses, which are to be attributed to the friction losses at the sealing cylinders of the respective sealing lips pressed by means of the cord spring(s) with full-surface contact against the running sleeve
Data Source
AI summary
A radial shaft seal seals a rotating shaft guided out of a liquid-loaded interior chamber, has a seal housing, an annular sealing body therein bearing against and sealing the shaft using a sealing lip, and an annular, metallic supporting body positioning the sealing body/bodies to seal interior from exterior. The supporting body presses the sealing body against the housing rear wall and is press fit and weldable there. A positioning cylinder with an outer shell is on the supporting body. An elastomer sealing body positioning cap with an elastomer sealing body is press fit on the outer shell so that the sealing body bears against a supporting body supporting web press-on collar and has a self-supporting supporting arch web, at the pressure space-side end of which is the sealing lip. A cord spring is centrally above the arch web on the sealing body outer circumference in an outer groove.