Planetary Gear Actuator with Offset Teeth for Noise Reduction
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Solution Overview
Problem
Existing planetary gear actuators for home automation screens suffer from noise issues due to synchronized oblique teeth, which cause significant meshing jumps and stress on the gears, and are costly and difficult to assemble.
Innovation Solution
A planetary reduction gear with offset oblique teeth, where one oblique toothing is angularly offset by a fixed angle relative to the other, and a straight toothing is integral with the satellite, reducing meshing jumps and stress, and simplifying assembly and production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If synchronized oblique teeth are used in the planetary gear, then the gear structure is simple to produce, but noise increases due to meshing jumps and stress variations
Solution Approach 1:
The patent applies asymmetry by angularly offsetting the two oblique toothings of the satellite relative to each other by a fixed angle between 0.25 and 0.75 times the pitch angle. This asymmetric configuration prevents the synchronized meshing jumps that occur with symmetric toothings, thereby reducing noise while maintaining manufacturing simplicity.
2Ease of manufacture
If synchronized oblique teeth are used in the planetary gear, then the gear structure is simple to produce, but assembly becomes delicate and difficult
Solution Approach 1:
The asymmetric angular offset between the two oblique toothings simplifies the assembly process by eliminating the need for precise helical movement alignment. The fixed offset angle provides a built-in alignment reference that guides the assembly process, making it less delicate and more straightforward.
3Device complexity
If synchronized oblique teeth are used in the planetary gear, then fewer components are required, but stress on the teeth increases due to strong force variations
Solution Approach 1:
The asymmetric angular offset between the two oblique toothings distributes the meshing forces more evenly over time. By preventing the synchronized engagement and disengagement of tooth pairs, the offset configuration reduces the amplitude of force variations and stress peaks on the teeth, thereby improving strength and durability.
Data Source
Figure 1
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Figure 3~6
AI summary
The actuator (1) has a planetary gearset formed of a crown wheel (70), an input shaft (10) and a planet gear (40a). Oblique teeth (41a, 42a) of the gear are angularly shifted to a fixed angle, whose value ranges between 0.25 and 0.75 times the value of an angular pitch of the teeth. Oblique teeth (21, 22) of the shaft are angularly shifted to a fixed angle, whose value is same as that of the angle between teeth. The gear has a straight external tooth (43a) rotatably integrated to the gear's oblique teeth and engaged with a straight internal tooth (73) of the wheel.