Planetary Ring Gear Mounting Structure for Vibration Isolation
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Solution Overview
Problem
Existing power transmission devices face challenges in reducing vibration and noise transmission from a ring gear to a case member, as vibrations in the radial direction are easily transmitted due to the location of the connection portion, leading to increased noise and vibration.
Innovation Solution
A power transmission device is designed with a planetary gear mechanism that includes a sun gear, ring gear, pinion gears, and a carrier, featuring an extending member from the ring gear's outer peripheral portion and a holding member connected to the case member, which attenuates radial vibrations by displacing them to the holding member, reducing transmission to the case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the connection portion between the ring gear and case member is located on the extension line from the gear portion in the radial direction, then the structure is simple, but vibration in the radial direction is easily transmitted to the case member, increasing noise and vibration
Solution Approach 1:
The patent introduces an extending member as an intermediary component between the ring gear and the case member. This extending member extends from the outer peripheral portion of the ring gear in the radial direction and connects to the case member, serving as a mediator that interrupts the direct vibration transmission path while maintaining structural connectivity
Solution Approach 2:
The patent moves the connection portion from the radial direction extension line to a position reached by extending in the thrust direction. This dimensional change in the connection geometry alters the vibration transmission characteristics by changing the orientation and path of force transmission from radial to axial
2Object-affected harmful factors
If the connection portion is positioned to reduce vibration transmission, then noise and vibration are suppressed, but the device size may increase
Solution Approach 1:
The extending member serves multiple functions simultaneously: it acts as a structural connector between the ring gear and case member, provides a pathway for vibration isolation, and maintains the overall compactness of the device. This multi-functionality allows vibration suppression without proportionally increasing device volume
Data Source
AI summary
A power transmission device includes: a planetary gear mechanism including a sun gear that is an external tooth gear, a ring gear that is an internal tooth gear located coaxially with the sun gear, a pinion gear that is an external tooth gear and meshes with the sun gear and the ring gear, and a carrier that rotatably supports the pinion gear; a case member that accommodates the planetary gear mechanism; an extending member that extends from an outer peripheral portion of the ring gear toward one side in a thrust direction; and a holding member that is provided at an end of the extending member on a side opposite to the ring gear side in the thrust direction, the holding member being connected to the case member for holding the ring gear.