Strain Wave Gear Inner Seal for Lubricant Leak Prevention
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Solution Overview
Problem
Conventional stress wave transmissions face issues with lubricant leakage and premature dry running due to the migration of used lubricant into the pivot bearing, leading to reduced sealing effectiveness and potential incompatibility between transmission and bearing lubricants.
Innovation Solution
An inner seal made of elastomer is introduced, designed as a static seal with O-ring configuration, arranged between the transmission component and the bearing ring, providing a sealing projection or lip to prevent lubricant ingress and featuring a prestressed or gap-seal design to enhance sealing efficacy, especially in small installation spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external radial shaft seal is used to seal the bearing space, then the bearing space is sealed against ingress of unwanted materials and escape of rolling bearing grease, but the seal cannot withstand exposure to large quantity of gearbox lubricant leading to lubricant leakage
Solution Approach 1:
The sealing system is divided into two separate seals: an inner seal (sealing lip 31) that seals the gear interior and an outer seal (radial shaft seal) that seals the bearing space. This segmentation allows each seal to be optimized for its specific function, with the inner seal protecting the outer seal from lubricant exposure.
Solution Approach 2:
The inner seal acts as an intermediary element between the gear interior and the bearing space. It prevents gearbox lubricant from reaching the outer seal, thereby protecting the outer seal from lubricant exposure while still allowing the outer seal to perform its sealing function.
2Reliability
If lubricant is supplied for lifetime lubrication of gear teeth and drive component bearing, then high torque transmission and positioning accuracy are achieved, but used lubricant migrates to the rotary bearing causing premature dry running
Solution Approach 1:
The harmful element (used lubricant) is extracted from the system by preventing it from reaching the bearing space. The inner seal removes the migration path of used lubricant from the gear interior to the bearing, ensuring that lubricant remains where it is needed.
Solution Approach 2:
The flexing motion of the transmission component, which causes lubricant migration, is converted into a beneficial lubrication mechanism. The flexing motion distributes lubricant to the gear teeth and drive component bearing, while the sealing system prevents over-migration to the rotary bearing.
3Weight of moving object
If the flexspline is designed as a thin-walled elastically deformable ring, then compact and lightweight gearbox is achieved, but lubricant can penetrate through the flexspline into the bearing space
Solution Approach 1:
The inner seal is nested within the gear interior, positioned between the flexspline and the bearing ring. This nested configuration allows the seal to protect against lubricant penetration through the thin-walled flexspline while maintaining the compact and lightweight design.
4Loss of substance
If a seal is added to prevent lubricant migration, then lubricant leakage is reduced, but device complexity increases
Solution Approach 1:
The inner seal serves multiple functions: it seals the gear interior, protects the outer seal from lubricant exposure, prevents lubricant migration to the bearing, and maintains positioning accuracy. This multi-functionality reduces the need for additional sealing components.
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 elastomer inner seal effectively reduces lubricant leakage and prevents foreign substances from entering the pivot bearing, ensuring reliable sealing over the service life while minimizing frictional losses and stick-slip behavior, thus preventing premature dry running and maintaining high transmission efficiency.
Implementation Method 1
an inner seal (12) made of elastomer, inserted between a transmission component (FS) and a bearing ring (5, 6) of the rotary bearing (30)
Implementation Method 2
an inner seal (12) made of elastomer
Data Source
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AI summary
The invention relates to a strain wave gear mechanism (1) with a gear mechanism component (CS) and an elastically deformable transmission component (FS) which is at least partially in alignment therewith in the radial direction (29) and can be deformed elliptically by way of a drive component (WG) which interacts therewith, in such a way that internal or external toothing systems (8, 9) which are provided on the gear mechanism component (CS) and the transmission component (FS) can be brought into engagement in opposite regions of an elliptical axis, in order to rotate the transmission component (FS) and the gear mechanism component (CS) relative to one another, wherein the transmission component (FS) and the gear mechanism component (CS) are mounted such that they can be rotated relative to one another by means of a pivot bearing (30) which has a bearing intermediate space (16). In order that the risk of a lubricant leak and/or premature dry running of the gear mechanism can be reduced reliably, there is a strain wave gear mechanism, in the case of which an interior space (28) of the strain wave gear mechanism (1), which interior space (28) is enclosed at least partially by the transmission component (FS) and the internal or external toothing system (8, 9) and adjoins the pivot bearing (30), is sealed by means of an inner seal (12) with respect to the bearing intermediate space (16) of the pivot bearing.