Spoked Hub Differential Assembly Torque Density
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Solution Overview
Problem
Conventional differential assemblies face challenges in maximizing power and torque density due to structural limitations, leading to issues such as wear, failure, and reduced durability under high loads, particularly in larger work machines.
Innovation Solution
A differential assembly design featuring a spoked torque-transmitting hub with a double press fit pinion support strategy, where the inner housing includes a torque transmitting hub with radial spokes and separate pinion support pin bores, allowing for robust assembly and reduced wear by decoupling the joint's torque transmission and spider support functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional open differential design is used, then the differential can allow smooth turning with differentiation, but the structural integrity and robustness are limited, reducing power and torque density
Solution Approach 1:
The differential housing is divided into multiple segments (first housing portion, second housing portion, third housing portion) that can be assembled together. This segmentation allows for a larger, more robust housing structure that can withstand higher loads while maintaining the necessary internal space for differential components, thereby improving both structural integrity and power/torque density
Solution Approach 2:
The differential assembly uses composite construction combining multiple housing portions with different functional characteristics. The housing segments are joined using interference fits and torque transmitting features to create a unified structure that optimizes both strength and power transmission capabilities
2Power
If the differential housing is designed for high strength and robustness, then power and torque density are maximized, but wear and failure occur under extreme high loads
Solution Approach 1:
The differential design incorporates load distribution features and torque transmitting mechanisms that are pre-configured to handle extreme loads. The housing portions include integrated torque transmitting hubs and pinion support structures that are designed beforehand to cushion and distribute high loads across multiple contact points, preventing localized wear and failure
Solution Approach 2:
The differential assembly uses dynamic load distribution through its pinion and gear arrangements. The housing portions are designed to flex and distribute loads dynamically during operation, allowing the structure to adapt to varying load conditions and reduce stress concentration points that would lead to wear and failure
3Power
If a one-piece spider member is used to support pinions, then torque transmission is efficient, but the joint's torque transmission and spider support functions interfere with each other, causing wear
Solution Approach 1:
The housing is segmented into multiple portions with distinct functions. The first housing portion supports the pinions, while the second and third housing portions form the torque transmitting joint. This segmentation separates the spider support function from the torque transmission function, eliminating interference and wear at the joint while maintaining efficient torque transmission through the dedicated torque transmitting hub
4Power
If the pinion support joint is positioned to transmit torque, then torque transmission is achieved, but the joint interferes with pinion support, leading to rapid wear
Solution Approach 1:
The differential housing is divided into functionally separate segments: the first housing portion is dedicated to pinion support with its own bearing surfaces and mounting features, while the second and third housing portions form a separate torque transmitting joint. This spatial and functional segmentation ensures that torque transmission forces do not interfere with pinion support, eliminating the wear mechanism that would otherwise reduce working life
Solution Approach 2:
The design introduces an intermediate torque transmitting hub that acts as a mediator between the external torque input and the pinion support structure. This intermediate element transfers torque through dedicated pathways that do not involve the pinion support joint, preventing wear and extending the working life of the pinion support components
Data Source
AI summary
A differential assembly for a machine includes a ring gear, first and second differential side gears and a plurality of pinions configured to mesh with the first and second side gears, and mounted on at least one pinion support pin. An inner differential housing is rotatably supported by an outer differential housing, and includes a torque transmitting hub configured to couple the ring gear with the first and second side gears via at least two pinions. The hub including a plurality of radial spokes and an outer rim portion having pinion support pin bores therein. A method of assembling a differential assembly for a machine includes coupling a spoked hub with a ring gear, and establishing a first torque transmission path between the ring gear and side gears of the differential, and establishing a second torque transmission path between a short portion of the differential housing comprising the hub and a long portion of the differential housing, the second torque transmission path including a joint coupling the short and long portions.