Differential Side Gear Boss Structure for Compact Shaft Coupling
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Solution Overview
Problem
Existing differential gear mechanisms are limited by the need for a large through hole to accommodate the output shaft, restricting the size reduction of the side gear and increasing material rigidity requirements.
Innovation Solution
The side gear design includes a boss portion protruding from the gear portion, with the output shaft connected closer to the boss than the gear boundary, and spline teeth engagement on both the boss and shaft, eliminating the need for a large through hole and reducing material rigidity demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a large through hole is formed in the side gear to accommodate the output shaft, then the output shaft can be connected, but the gear portion size and material thickness increase to maintain rigidity
Solution Approach 1:
The side gear is segmented into two functional portions: a gear portion for meshing with pinion gears and a boss portion for output shaft connection. This segmentation allows the output shaft to connect to the boss portion rather than requiring a through hole in the gear portion, thereby reducing the gear portion size while maintaining connection functionality.
Solution Approach 2:
The connection point for the output shaft is moved from the gear portion to the boss portion, which protrudes axially from the gear portion. This dimensional relocation allows the output shaft to connect at a position closer to the boss portion than the boundary between the gear portion and boss portion, eliminating the need for a large through hole in the gear portion.
2Ease of operation
If a large through hole is formed in the side gear, then the output shaft can be connected, but the material thickness and rigidity requirements increase
Solution Approach 1:
By segmenting the side gear into a gear portion and a boss portion, the structural requirements for rigidity are separated. The gear portion only needs to maintain rigidity for gear meshing operations, while the boss portion handles the torque transmission from the output shaft. This eliminates the need for excessive material thickness in the gear portion that would be required if a large through hole were formed.
Solution Approach 2:
The boss portion is designed with local quality differences - it has a larger outer diameter than the gear portion to provide sufficient torque transmission capacity. The spline teeth are formed on the outer peripheral face of the boss portion end, creating a localized high-strength region that handles the connection loads without requiring the entire gear portion to have increased thickness.
3Power
If the output shaft is connected to the gear portion through a through hole, then torque can be transmitted, but the gear portion must be larger to maintain structural integrity
Solution Approach 1:
The side gear is divided into a gear portion for power reception from pinion gears and a boss portion for power transmission to the output shaft. This segmentation allows torque transmission to occur through the boss portion with spline teeth engagement, rather than through a large through hole in the gear portion, thereby reducing the overall side gear size while maintaining torque transmission capability.
Solution Approach 2:
The boss portion acts as an intermediary structure between the gear portion and the output shaft. It receives torque from the gear portion and transmits it to the output shaft via spline teeth engagement. This intermediary structure eliminates the need for a large through hole in the gear portion, as the torque transmission path is routed through the boss portion instead.
Data Source
AI summary
This differential gear mechanism is provided with a case member having a cylindrical housing portion and held so as to be rotatable about a center axis of the housing portion, a pinion gear provided inside the housing portion so as to be revolvable about a center axis of the housing portion, and a side gear to which a torque is transmitted from the pinion gear and an output shaft is connected, and a side gear is provided with a pinion gear. A meshing gear portion and a boss portion protruding toward the rear side of the gear portion are provided, and the output shaft is connected to the side gears at a boss portion side rather than a border portion between the gear portion and the boss portion in the rotation center axis direction of the side gears.