Strain Wave Gear Gap-Filling Ring to Prevent Lubricant Pooling
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Solution Overview
Problem
Existing strain wave gearings face issues with lubricant pooling in gaps between internally and externally toothed gears, leading to improper lubrication and increased mass due to metal protrusions to prevent large gaps.
Innovation Solution
A gap-filling member made of an impermeable, lightweight material, such as resin, is inserted into the annular gap to prevent lubricant pooling without increasing the overall mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal members are used to fill gaps and prevent lubricant pooling, then lubrication is improved, but mass increases
Solution Approach 1:
The patent changes the material parameter from metal to resin, fundamentally altering the density and weight characteristics while maintaining the gap-filling function. This parameter change resolves the contradiction by providing lubricant pooling prevention without the mass penalty of metal components.
Solution Approach 2:
The resin gap-filling member serves as a functional equivalent to metal protrusions but with significantly reduced mass. While resin may have different durability characteristics, it effectively performs the lubricant containment function without increasing device mass, addressing the weight-reliability tradeoff.
2Weight of stationary object
If a large gap is allowed between internally toothed gear and main bearing, then mass is reduced, but lubricant pools in the gap causing improper lubrication
Solution Approach 1:
The resin gap-filling member acts as an intermediary element between the internally toothed gear and main bearing. It mediates the space relationship, preventing lubricant pooling while allowing the gap to remain sufficiently large to avoid metal-to-metal contact and reduce mass. This intermediary resolves the contradiction by decoupling the gap size from the lubricant containment function.
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
Prevents lubricant pooling while maintaining proper lubrication and reducing mass by using a lightweight, impermeable gap-filling member.
Implementation Method 1
a gap-filling member that is inserted in the gap portion in order to fill in the gap portion, and that is attached to at least one of the device housing and the internally toothed gear, the gap-filling member being formed of an impermeable material that does not let through a lubricant
Data Source
Figure 1
Figure 2
AI summary
The strain wave gear device (4) is provided with a device housing (41), an internally toothed gear (42), and an annular gap portion (47) which is formed between an externally toothed gear (43) and a main bearing (46) and surrounds a cylindrical part (43a) of the externally toothed gear (43). In order to fill the gap portion (47), a gap-filling ring (48) made of a lightweight resin material is attached to the gap portion (47). By appropriately setting the contour shape of the gap-filling ring (48) and forming the gap-filling ring (48) using a material having a small unit volume weight, the gap portion (47) formed on the outer peripheral side of the externally toothed gear (43) is filled without causing unnecessary increase in mass such that unwanted stagnation of a lubricant can be prevented.