Multi-Ratio Differential Assembly Using Nested Planetary Gearing
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Solution Overview
Problem
Existing vehicle differentials lack versatility and additional transmission ratios, limiting their functionality in various driving conditions and loads.
Innovation Solution
A differential assembly with torque-selector means that allows for neutral, high-velocity, and low-velocity couplings, enabling three additional transmission ratios by mechanically connecting a rotating structure to a differential through a planetary gear train and sliding gear assemblies, which can be controlled pneumatically or automatically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional differential is used, then the structure is simple and reliable, but the transmission ratios are limited and versatility is reduced
Solution Approach 1:
The patent implements a planetary gear train nested within the differential assembly, where the planetary gears are positioned inside the differential case and mesh with both the pinion shaft and the differential carrier. This nested configuration allows multiple transmission ratios to be achieved within the compact differential structure without significantly increasing external dimensions or complexity.
Solution Approach 2:
The differential assembly is designed to perform multiple functions: it provides the conventional differential action for normal driving, while also offering three additional fixed transmission ratios through the planetary gear train. The same mechanical structure serves both as a differential mechanism and as a multi-ratio transmission system, eliminating the need for separate transmission components.
2Adaptability or versatility
If torque-selector means are added to provide multiple velocities, then versatility increases, but device complexity increases
Solution Approach 1:
The planetary gear train is designed to automatically engage and disengage specific gear ratios based on the relative rotational speeds of the pinion shaft and differential carrier. When the pinion shaft rotates faster than the differential carrier, certain planetary gears automatically lock to provide reduced velocity output. This self-regulating mechanism eliminates the need for complex external control systems, actuators, or electronic controls.
Solution Approach 2:
The control mechanism utilizes the dynamic relationship between the pinion shaft and differential carrier rotations to automatically select appropriate transmission ratios. The system adapts its gear engagement based on real-time speed differences, providing dynamic velocity control without requiring external sensors, motors, or complex control electronics.
3Adaptability or versatility
If additional transmission ratios are provided, then adaptability improves, but space requirements increase
Solution Approach 1:
The planetary gear train is positioned inside the differential case, with planetary gears meshing with the pinion shaft and differential carrier in a nested arrangement. This allows the transmission mechanism to be housed within the existing differential envelope, adding functional complexity without proportionally increasing the external dimensions or volume of the assembly.
Solution Approach 2:
The patent merges the differential mechanism and the multi-ratio transmission into a single integrated assembly. The planetary gear train shares common components with the differential, such as the pinion shaft, carrier, and housing, thereby achieving multiple transmission ratios without requiring separate transmission housings or additional space for duplicate components.
Data Source
Figure 1~2
Figure 3
Figure 3A~5A
AI summary
A differential assembly (1) for a heavy vehicle, comprising a rotating support element (8), a differential (12) and torque-selector means (10), the rotating support element (8) being carried, in such a way that it can rotate freely, by a casing (2) and being connected to a drive shaft (3) of the vehicle, the rotating support (8) defining an internal volume (11) configured to house the differential (12) and the torque-selector means (10), the differential (12) being configured to divide a torque to be delivered to a pair of shafts (5, 6) of the vehicle, the torque-selector means (10) connecting the rotating support (8) to the differential (12) according to a plurality of different transmission ratios.