Strain Wave Gear Lubrication Using Separate Greases Without Seals
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Solution Overview
Problem
In strain wave gearing, the mixing of lubricants between the inner-side and outer-side lubrication portions leads to decreased efficiency and wear, especially during high loads, despite efforts to partition these areas, as commonly used lubricants are often the same for both portions.
Innovation Solution
A method where different types of grease are used for the inner-side and outer-side lubrication portions, with varying amounts based on operating conditions, such as steady or intermittent operations, to prevent mixing without the need for a sealing member, thereby simplifying the structure and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different types of grease are used for inner-side and outer-side lubrication portions, then lubricating properties are optimized for each portion, but lubricants mix together during operation
Solution Approach 1:
The invention divides the lubrication system into two separate chambers (inner-side and outer-side lubrication portions) and uses a sealing member to maintain the segmentation. This allows different types of grease to be used in each chamber while preventing mixing, thus optimizing lubricating properties for each specific portion while maintaining lubricant separation.
Solution Approach 2:
A sealing member acts as an intermediary element between the inner-side and outer-side lubrication portions. This sealing member prevents direct contact and mixing between the different lubricants while allowing the system to operate with optimized lubrication in each separate zone.
2Stability of the object's composition
If sealing members are used to partition lubrication portions, then lubricant mixing is prevented, but device complexity increases
Solution Approach 1:
The sealing member is positioned to perform multiple functions: it seals the inner-side lubrication portion to prevent lubricant mixing, simultaneously seals the outer-side lubrication portion, and maintains the structural integrity of the gear assembly. This multi-functionality reduces the need for additional separate sealing components.
3Device complexity
If same lubricant is used in both lubrication portions, then device complexity is reduced, but efficiency and wear performance decrease during high loads
Solution Approach 1:
The invention applies different lubricant types to different locations within the gear system based on specific lubrication requirements. The inner-side lubrication portion receives one type of grease optimized for wave generator sliding, while the outer-side lubrication portion receives another type of grease optimized for meshing portions, ensuring optimal performance in each specific area.
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 approach effectively prevents lubricant mixing during intermittent operations, maintains durability, and reduces friction loss, making it practical for applications like robots and conveyors without the need for a sealing mechanism.
Implementation Method 1
a flexible externally toothed gear (3) having an ellipsoidal shape capable of being deformed elastically by the wave generator (4)
Implementation Method 2
an inner-side lubrication portion (12) and an outer-side lubrication portion (11) are each lubricated using grease
Data Source
AI summary
When a strain wave gearing is used in an application for an operation of repeating startup/stopping, an outer-side lubrication portion and an inner-side lubrication portion, which are lubricated using different types of grease, remain in a communicating state without being divided using a seal member or the like. The outer-side lubrication portion is supplied with a much smaller amount of grease than the amount that would be required if used in an application such as a steady operation. Similarly, the inner-side lubrication portion is also supplied with a much smaller amount of grease than the amount that would be required if used in an application such as a steady operation. Essentially, the outer-side lubrication portion and the inner-side lubrication portion can be lubricated appropriately using different types of grease, without the grease becoming mixed.