Strain Wave Gear Wave Generator Hollow Diameter
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Solution Overview
Problem
Existing strain wave gearing systems face challenges in increasing the hollow diameter of the hollow part without expanding the outside diameter, particularly in wave generators with rigid plugs having a through-hole, where a needle roller bearing with reduced radial thickness is required to achieve this.
Innovation Solution
A wave generator design featuring a needle roller bearing with an ellipsoidal inner ring trajectory surface formed directly on the rigid plug, eliminating the need for separate inner and outer rings, allowing for a larger hollow through-hole and reduced radial thickness, enabling a compact and larger hollow strain wave gearing system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a ball bearing is used in the wave generator, then the bearing can support radial loads, but the radial thickness increases and the hollow diameter cannot be increased
Solution Approach 1:
The patent changes the bearing type from ball bearing to needle roller bearing, which has a fundamentally different geometric parameter (radial thickness). Needle rollers have a much smaller radial thickness compared to ball bearings, allowing the hollow diameter to be increased while still supporting radial loads effectively.
Solution Approach 2:
The patent employs an ellipsoidal outer peripheral surface on the rigid plug that interfaces with the needle roller bearing. This curved surface geometry allows the needle rollers to be properly positioned and loaded, enabling the compact bearing design to function effectively in supporting radial loads while maintaining minimal radial thickness.
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 design allows for a significant increase in the hollow diameter of the strain wave gearing system while maintaining a compact size, as the needle roller bearing reduces the radial thickness and eliminates the need for additional components to restrict needle roller movement, enhancing the system's efficiency and compactness.
Implementation Method 1
a plurality of needle rollers (34) mounted in a rollable state between the inner ring trajectory surface (31) and the outer ring trajectory surface (33)
Implementation Method 2
an outer ring (32) capable of flexing in the radial direction
Data Source
AI summary
A wave generator of a hollow strain wave gearing has a rigid plug and a needle roller bearing. The needle roller bearing has an inner ring trajectory surface formed in the plug external peripheral surface, a flexible outer ring, an outer ring trajectory surface formed in an inner peripheral surface of the outer ring, and needle rollers. An inner ring trajectory groove is formed in the plug external peripheral surface, and the inner ring trajectory surface is formed in a groove bottom surface of the inner ring trajectory groove. Inner-ring-side restricting surfaces for restricting the needle rollers from moving in the center axis direction are formed in groove side surfaces on both sides of the inner ring trajectory groove. A wave generator can be obtained, which is suitable for increasing the hollow diameter of a strain wave gearing.