Planetary Gear Train for Automatic Transmission with Merged Gears

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Solution Overview

Problem

Current automatic transmissions with increased shift stages face challenges in installability, production cost, weight, and power flow efficiency due to the need for more parts, which complicates achieving better fuel consumption and drivability.

Innovation Solution

A planetary gear train design incorporating three simple planetary gear sets and one compound planetary gear set, along with six engagement elements, including clutches and brakes, to achieve at least ten forward speeds and one reverse speed, optimizing the arrangement to minimize the number of parts while enhancing performance and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of planetary gear sets and engagement elements is increased to achieve more shift stages, then the fuel consumption and drivability are improved, but the installability, production cost, weight and power flow efficiency deteriorate

Engineering Contradiction:

Improvefuel consumptionVSAvoidnumber of parts

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent combines multiple planetary gear sets (first, second, third planetary gear sets with fourth planetary gear set) and engagement elements (first to third clutches, first to third brakes) into a unified transmission system where components share common elements such as the sun gear, planet carrier, and ring gear. This merging reduces the total number of independent parts while achieving ten forward speeds and reverse speed, thereby improving fuel consumption without proportionally increasing device complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The fourth planetary gear set serves multiple functions by providing both forward speed reduction and reverse speed capability. The engagement elements (clutches and brakes) are designed to selectively connect different rotation elements across multiple planetary gear sets, enabling a single engagement element to control multiple gear ratios. This multi-functionality reduces the number of dedicated components needed for each shift stage

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

Engineering Contradiction:

Improvefuel consumptionVSAvoidweight

Core Design Contradiction:

ProductivityVSWeight of moving object

Solution Approach 1:

The patent merges multiple planetary gear sets into a compact arrangement where the first, second, and third planetary gear sets share common rotation elements (sun gear, planet carrier, ring gear). This consolidation reduces the cumulative weight that would result from completely separate gear sets, while still achieving ten forward speeds and reverse speed necessary for improved fuel consumption

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The planetary gear sets are arranged in a nested configuration where rotation elements of one gear set are integrated with rotation elements of adjacent gear sets. The fourth planetary gear set is positioned to share components with the third planetary gear set, creating a compact, space-efficient layout that minimizes overall transmission weight while maintaining multiple shift stages

Inventive Principle:

Principle #7Nested doll (Nesting)

3Productivity

Engineering Contradiction:

Improvefuel consumptionVSAvoidinstallability

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent combines multiple planetary gear sets and engagement elements into a integrated transmission assembly where components are pre-positioned and interconnected. The first shaft connects the second rotation element to the input shaft, the second shaft connects the eleventh rotation element to the output shaft, and additional shafts interconnect various rotation elements. This merged structure simplifies installation by reducing the number of separate assemblies that must be individually positioned and aligned

Inventive Principle:

Principle #5Merging (Combining)

4Productivity

If the number of planetary gear sets and engagement elements is increased to achieve more shift stages, then the fuel consumption and drivability are improved, but the power flow efficiency deteriorates

Engineering Contradiction:

Improvefuel consumptionVSAvoidpower flow efficiency

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent merges multiple planetary gear sets into a unified power transmission path where torque from the input shaft flows through interconnected rotation elements (sun gears, planet carriers, ring gears) of the first, second, third, and fourth planetary gear sets to the output shaft. This consolidated power flow path reduces energy losses compared to separate, independent gear sets, while still achieving ten forward speeds and reverse speed for improved fuel consumption

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10330180B2Planetary gear train of automatic transmission for vehicle

Publication Date: 2019.06.25 HYUNDAI MOTOR CO LTD

AI summary

A planetary gear train may include input and output shafts, first to fourth planetary gear sets respectively having first to third, fourth to sixth, seventh to ninth, and tenth to thirteenth elements, a first shaft connected to the second element and the input shaft, a second shaft connected to the eleventh element and the output shaft, a third shaft connected to the first and seventh elements, a fourth shaft connected to the fifth and twelfth elements, a fifth shaft connected to the eighth and tenth elements, a sixth shaft connected to the thirteenth element, and a plurality of shafts each selectively connecting a corresponding element to a transmission housing, the corresponding element being an element of the first, second and third planetary gear sets which is not interconnected.