Differential Device Oil Groove Offset for Rigidity
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Solution Overview
Problem
Conventional differential devices experience reduced support rigidity and durability due to the placement of oil grooves in regions subjected to large thrust reaction forces, particularly when the input member is thinner and lighter, leading to decreased load-bearing capabilities.
Innovation Solution
The differential device incorporates an oil groove that extends from the shaft portion of the output gear to the washer, offset from the meshing portion, and includes a side wall portion with through-holes or recessed holes to reduce weight and enhance lubrication, while an oil reserving portion adjusts lubricant supply, ensuring effective lubrication and maintaining support rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil groove is formed in the region part located on the back surface side of the meshing portion in the surface of the input member, then lubrication is improved, but support rigidity decreases and durability deteriorates
Solution Approach 1:
The oil groove is extracted from the high-load region (back surface side of meshing portion) and relocated to a different position on the input member surface. This removes the harmful effect of the groove on support rigidity while preserving the lubrication function through alternative positioning that still allows oil supply to the washer and gear interfaces.
Solution Approach 2:
The patent applies local quality by creating a recessed portion with an oil groove in a specific local region of the input member, rather than uniformly modifying the entire surface. The recessed portion is strategically positioned to provide lubrication without compromising the structural integrity of the high-load bearing regions.
2Weight of moving object
If the input member is reduced in thickness and weight, then productivity and material usage are improved, but load-bearing capability and durability decrease
Solution Approach 1:
Instead of uniformly thickening the entire input member, the patent applies local quality by creating a recessed portion with an oil groove in a specific local region. This allows the input member to remain thin and lightweight overall while providing enhanced lubrication in critical areas to compensate for the reduced material, thereby maintaining load-bearing capability without increasing overall weight.
Solution Approach 2:
The oil groove in the recessed portion acts as an intermediary mechanism that improves lubrication effectiveness for the thinner input member design. By enhancing the lubrication film formation and retention in critical contact zones, the recessed portion compensates for the reduced structural mass, allowing the thin input member to sustain required loads.
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 configuration effectively lubricates the washer and reduces the load burden on the input member, enhancing durability and allowing for a thinner, lighter design without compromising torque transmission or static torsion load strength.
Implementation Method 1
using centrifugal force, lubricant oil can be effectively supplied from the periphery of the shaft portion of the output gear to the back surface of the washer via the oil groove
Data Source
AI summary
A differential device includes: an input member inputted with driving force; a differential gear supported in the input member and capable of rotating relative to the input member and revolving around rotation center of the input member with rotation of the input member; paired output gears each including a tooth portion meshing with the differential gear and a shaft portion located radially inward of the tooth portion; a washer interposed between the input member and back surface of the tooth portion; and an oil groove provided in a recess shape in surface of the input member facing back surface of each output gear and extending from periphery of the shaft portion to back surface of the washer. The oil groove is arranged offset in peripheral direction of the output gear from a meshing portion between the tooth portion and the differential gear.