Offset Planet Gear Fastener Assembly to Prevent Loosening
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Solution Overview
Problem
Existing planetary gear systems face challenges in securely fastening planet gears to carriers without causing unintended rotation or loosening of fasteners, which can lead to system instability and failure.
Innovation Solution
A planetary gear fastener assembly that includes a washer positioned against the axial end of a planet gear and a fastener extending through the washer to couple it to the carrier, with the fastener axis radially offset from the planet gear axis by more than 1 millimeter, ensuring secure coupling without rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fastener is used to secure planet gears to carriers, then the planet gear can be attached to the carrier, but the fastener may rotate or loosen unintentionally causing system instability
Solution Approach 1:
The fastener assembly introduces asymmetry through the radially offset fastener axis relative to the planet gear axis. This offset positioning creates an asymmetric loading condition that prevents rotation and loosening by ensuring the fastener does not align with the rotational axis of the planet gear, thereby eliminating the possibility of unintended rotation while maintaining secure attachment
Solution Approach 2:
The washer acts as an intermediary component between the fastener and the planet gear. It distributes the load from the fastener over a larger surface area of the planet gear, preventing direct point loading and reducing stress concentrations. This intermediary element enhances the reliability of the fastener connection by improving load distribution and preventing fastener loosening under operational loads
2Device complexity
If the fastener axis is aligned with the planet gear axis, then the assembly is simple, but unintended rotation and loosening occurs
Solution Approach 1:
The design deliberately creates asymmetry by offsetting the fastener axis from the planet gear axis by more than 1 millimeter. This asymmetric configuration ensures that the fastener loading path does not coincide with the planet gear rotational path, preventing rotation and loosening while maintaining a relatively simple overall assembly structure
3Stress or pressure
If the washer is positioned with its axis aligned to the planet gear axis, then the load distribution is optimized, but the fastener still requires radial offset to prevent rotation
Solution Approach 1:
The washer serves as a load-distributing intermediary positioned against the planet gear with its axis aligned to the planet gear axis, optimizing stress distribution. Simultaneously, the fastener axis is offset radially from the planet gear axis, creating a geometric constraint that prevents rotation. The combination of these two features addresses both load distribution and rotation prevention requirements
Solution Approach 2:
While the washer axis aligns with the planet gear axis for optimal load distribution, the fastener axis is deliberately offset radially by more than 1 millimeter. This asymmetric fastener positioning prevents rotation by ensuring the fastener loading path does not intersect with the planet gear rotational path, complementing the symmetric load distribution provided by the washer
Data Source
AI summary
A planetary gear system and a planet gear fastener assembly for a planetary gear system includes a planet gear having a planet gear axis, a carrier connected to the planet gear, and a sun gear that engages the planet gear. The planetary gear fastener assembly includes a washer having a washer axis and configured to be positioned against an axial end of the planet gear and a fastener extending through the washer to couple the washer to the carrier. The fastener includes a fastener axis positioned to be radially offset from the planet gear axis of the planet gear.