Strain Wave Gear Floating Wave Generator and Sealing
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Solution Overview
Problem
Existing strain wave gear systems face challenges in installation precision, bearing misalignment, eccentric loading, and inefficient lubrication and sealing methods, which affect performance and reliability.
Innovation Solution
A strain wave gear system with a ring gear, wave generator, and flexspline design that includes precise positioning of bearings and a sealing system using a protrusion and cavity to ensure consistent sealant application, along with a lubricating system using plungers to deliver precise grease distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ball bearings are used to constrain the wave generator, then the manufacturer can properly position the wave generator, but the bearings become over-constrained and experience undesirable radial loads due to manufacturing errors and eccentricities
Solution Approach 1:
The patent removes the wave generator from the constrained position and instead allows it to float freely within the flexspline. The input shaft is then coupled to the wave generator through a coupling device that provides compliance, extracting the constraint function from the bearing system and eliminating the harmful radial loads while maintaining positioning accuracy through the compliant coupling mechanism.
Solution Approach 2:
The patent introduces a compliant coupling device that allows dynamic adjustment and movement between the input shaft and wave generator. This dynamic compliance mechanism accommodates manufacturing tolerances and eccentricities, enabling the system to adapt during operation rather than being locked into a rigid, over-constrained configuration.
2Manufacturing precision
If custom modifications are made to the input to position the wave generator, then proper positioning is achieved, but system costs increase significantly
Solution Approach 1:
The patent divides the positioning function into separate components: the wave generator floats freely within the flexspline, and the input shaft connects through a compliant coupling device. This segmentation eliminates the need for custom modifications to the input shaft itself, allowing standard manufacturing processes to be used while achieving proper positioning through the modular coupling mechanism.
Solution Approach 2:
The compliant coupling device automatically positions and aligns the wave generator within the flexspline during assembly without requiring precision machining or custom modifications to the input shaft. The coupling mechanism self-adjusts to accommodate tolerances, making the system easier to manufacture while maintaining positioning accuracy.
3Reliability
If sealant is applied in traditional methods, then sealing is provided, but the application is inconsistent and difficult to control
Solution Approach 1:
The patent incorporates a sealant reservoir and delivery system that pre-positiones and controls sealant application before final assembly. The sealant is delivered through controlled channels to specific locations, ensuring consistent application without requiring manual intervention or complex sealing procedures during assembly.
Solution Approach 2:
The patent introduces a sealant delivery mechanism that acts as an intermediary between the sealant source and the sealing interface. This mediator component ensures uniform distribution and controlled application of sealant, replacing inconsistent manual or traditional sealing methods with a precision delivery system.
4Reliability
If traditional lubrication methods are used, then bearings are lubricated, but grease distribution is inefficient and imprecise
Solution Approach 1:
The patent incorporates grease reservoirs and plunger-based delivery systems that pre-position lubricant before bearing operation. The plungers force grease through controlled channels directly to bearing interfaces, ensuring efficient distribution without requiring external lubrication maintenance during operation.
Solution Approach 2:
The patent introduces grease delivery channels and plunger mechanisms that act as intermediaries between the lubricant source and bearing surfaces. This intermediary system ensures precise and efficient grease distribution, replacing traditional imprecise lubrication methods with a controlled delivery mechanism.
Data Source
AI summary
A strain wave gear system (10) includes first and second sets of ball bearings (80,82) located intermediate a flange (84) and a retainer plate (88) rotatable with an output (54) and a radially oriented flat disc (74) of the input including strain relief (76). Strain relief (76) is a helical slot in a coupling (70) located radially within the wave generator (94) and the ring gear (22). The ring gear (22) is sealed by a sealing system including sealant (42) forced by a protrusion (34) of the cap (24) entering into a cavity (36) through a channel (40) into a relief volume (38) of the housing (12). The bearing (48) rotatably mounting the housing (12) to the output (54) is lubricated by a lubricating system including plungers (110) threadably received in axial bores (102) intersecting with radial bores (104) in communication with radial holes (47) of the bearing (48).