Compound Planetary Differential for Compact Vehicle Drivetrains
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Solution Overview
Problem
Conventional differential apparatuses for vehicles, particularly those using bevel gears, face challenges due to their heavy weight and large size, which hinder fuel efficiency and weight reduction efforts in the development of environment-friendly vehicles.
Innovation Solution
A compound planetary gear set comprising a combination of first and second planetary gear sets, where the first set is a single pinion gear set and the second set is a double pinion gear set, sharing pinion gears and a planet carrier, which reduces overall size and enhances power delivery efficiency and durability by canceling forces between pinion gears at engagement points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bevel gear type differential apparatus is used, then the differential function is achieved, but the weight and size increase
Solution Approach 1:
The patent replaces the conventional bevel gear mechanical system with a planetary gear system. The planetary gear set includes a sun gear, planet gears, and a ring gear, which fundamentally changes the mechanical transmission approach from bevel gear meshing to planetary gear rotation, achieving weight reduction while maintaining differential functionality
Solution Approach 2:
The patent changes the gear ratio parameters and mechanical configuration from traditional bevel gear geometry to planetary gear parameters. By adjusting the number of teeth on sun gear (30), planet gears (32), and ring gear (40), along with modifying the carrier (20) structure, the system achieves optimized weight and size parameters while preserving the differential function
2Reliability
If a bevel gear type differential apparatus is used, then the differential function is achieved, but the size increases
Solution Approach 1:
The patent replaces the conventional bevel gear mechanical system with a planetary gear system. The planetary gear set includes a sun gear, planet gears, and a ring gear, which fundamentally changes the mechanical transmission approach from bevel gear meshing to planetary gear rotation, achieving size reduction while maintaining differential functionality
Solution Approach 2:
The planetary gear system employs a nested configuration where planet gears (32) are arranged around and mesh with both the sun gear (30) at the center and the ring gear (40) at the outer perimeter. The planet carrier (20) holds and rotates these planet gears, creating a compact nested structure that significantly reduces the overall volume compared to the extended bevel gear arrangement
3Power
If conventional pinion gear arrangement is used, then power transmission is achieved, but power delivery efficiency and durability are reduced
Solution Approach 1:
The patent merges the functions of multiple pinion gears into a unified planetary gear system. The planet gears (32) simultaneously engage with both the sun gear (30) and ring gear (40), combining multiple transmission paths into a single integrated mechanism that improves power delivery efficiency and durability through force distribution across multiple engagement points
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
The solution improves power delivery efficiency and durability while reducing the overall size of the differential apparatus, making it suitable for both forward and rearward driving conditions in electric and internal combustion engine vehicles.
Implementation Method 1
a compound planetary gear set formed as a combination of first and second planetary gear sets sharing a plurality of first pinion gears and a planet carrier where each of second pinion gears of the second planetary gear set is externally gear-meshed with two adjacent first pinion gears
Data Source
AI summary
An exemplary differential apparatus for a vehicle includes: a compound planetary gear set and a planet carrier. In particular, the compound planetary gear set is formed as a combination of first and second planetary gear sets, the first planetary gear set is formed as a single pinion planetary gear set having a first sun gear and a plurality of first pinion gears, and the second planetary gear set is formed as a double pinion planetary gear having a second sun gear disposed coaxially and in parallel with the first sun gear, the plurality of first pinion gears shared with the first planetary gear set, and a plurality of second pinion gears. The planet carrier has an exterior circumference connected to an external gear and is connected to first and second pinion shafts that rotatably support the first and second pinion gears of the second planetary gear set.