Helical Planetary Gear Carrier Layout for Lubricating Oil Discharge
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Solution Overview
Problem
In helical-teeth planetary gear mechanisms used for electrification, lubricating oil flows along the rotation axis and becomes biased, making it difficult to discharge between tooth surfaces and the planetary carrier, resulting in rotation loss.
Innovation Solution
The planetary gear mechanism includes a plurality of planetary gears with helical teeth, a sun gear, a ring gear, shafts, support walls, and connecting sections. The connecting sections are arranged between adjacent planetary gears in a circumferential direction, with a wider distance on the side of the first end portions than on the side of the second end portions, facilitating lubricating oil discharge while maintaining structural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the distance between the planetary carrier and the tooth surface of the planetary gears is increased to facilitate lubricating oil discharge, then lubricating oil discharge is improved, but the strength to transmit torque deteriorates
Solution Approach 1:
The connecting sections are designed with asymmetric distance characteristics: the distance to planetary gears on the first circumferential direction side is intentionally made wider to facilitate lubricating oil discharge, while the distance to planetary gears on the second circumferential direction side is kept narrower to maintain structural strength and torque transmission capability. This local differentiation resolves the contradiction by applying different spatial characteristics to different locations.
Solution Approach 2:
The connecting sections are configured with asymmetric geometry where the first end portions are positioned at different distances from adjacent planetary gears compared to the second end portions. Specifically, the distance on the first circumferential direction side is wider than on the second circumferential direction side, creating an asymmetric structure that simultaneously enables lubricating oil discharge and maintains mechanical strength.
2Power
If helical-teeth gears are used to reduce noise and enhance transmission torque, then transmission performance is improved, but lubricating oil discharge between tooth surfaces and planetary carrier becomes difficult
Solution Approach 1:
The connecting sections create localized spatial variations that facilitate lubricating oil discharge in specific areas where helical teeth generate oil flow along the rotation axis. By making the distance wider on the first circumferential direction side, the invention provides dedicated discharge paths that address the lubrication problem specific to helical-teeth gears while preserving their torque transmission advantages.
Data Source
AI summary
A planetary gear mechanism includes a plurality of planetary gears with helical teeth, a sun gear disposed inside the plurality of planetary gears to mesh with the plurality of planetary gears, a ring gear disposed outside the plurality of planetary gears to mesh with the plurality of planetary gears, a plurality of shafts rotatably supporting the plurality of planetary gears, a first support wall supporting first ends of the plurality of shafts, a second support wall supporting second ends opposite to the first ends of the plurality of shafts, and a plurality of connecting sections arranged between the planetary gears adjacent in a circumferential direction. The second support wall is disposed opposite to the first support wall. The plurality of connecting sections connect the first support wall and the second support wall. Each connecting section includes first and second end portions connected to the first and second support walls.