Planetary Gear Train for Automatic Transmission with Merged Sets

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Solution Overview

Problem

Existing automatic transmissions with multiple speed stages face challenges in reducing complexity, production cost, weight, and power flow efficiency, which affect fuel consumption and drivability.

Innovation Solution

A planetary gear train with four single pinion planetary gear sets and six control elements is designed to achieve at least forward tenth speeds and one reverse speed, improving power delivery and fuel efficiency by minimizing parts and optimizing engine rotation speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the number of parts is increased to achieve more shift stages, then the number of speed stages is increased, but installability, production cost, weight and power flow efficiency deteriorate

Engineering Contradiction:

Improvenumber of speed stagesVSAvoidnumber of parts

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple planetary gear sets into a unified structure where four planetary gear sets share common elements (input shaft, output shaft, carrier, and ring gear). This consolidation allows achieving 10 forward speeds and reverse speeds without proportionally increasing the number of independent parts, thereby resolving the contradiction between multiple speed stages and device complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The planetary gear sets are designed with multi-functional elements that serve multiple purposes. The common carrier and ring gear structure enables the same components to participate in multiple gear ratio formations, allowing the system to achieve diverse speed stages without requiring separate dedicated parts for each function

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If the number of parts is increased to achieve more shift stages, then the number of speed stages is increased, but production cost increases

Engineering Contradiction:

Improvenumber of speed stagesVSAvoidproduction cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

By merging four planetary gear sets into a compact configuration with shared components, the patent reduces the total part count compared to using separate gear sets for each speed stage. This consolidation directly lowers production cost through reduced material usage, fewer manufacturing operations, and simplified assembly processes while maintaining 10+ forward speeds and reverse capability

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If the number of parts is increased to achieve more shift stages, then the number of speed stages is increased, but weight increases

Engineering Contradiction:

Improvenumber of speed stagesVSAvoidweight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent combines four planetary gear sets into a single integrated transmission unit where components are shared across multiple gear ratio formations. This merging eliminates the need for duplicate heavy components that would be required if separate gear sets were used for each speed stage, thereby achieving multiple speed stages without proportional weight increase

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If the number of parts is increased to achieve more shift stages, then the number of speed stages is increased, but power flow efficiency deteriorates

Engineering Contradiction:

Improvenumber of speed stagesVSAvoidpower flow efficiency

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The integrated planetary gear set configuration creates direct power flow paths through shared components, reducing the number of power transmission interfaces and potential loss points. The unified structure allows torque to flow efficiently through common carriers and ring gears across multiple speed stages, maintaining power flow efficiency despite achieving 10 forward speeds and reverse speeds

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9897169B2Planetary gear train of automatic transmission for vehicle

Publication Date: 2018.02.20 HYUNDAI MOTOR CO LTD

AI summary

A planetary gear set of an automatic transmission for a vehicle may include an input shaft for receiving an engine torque, an output shaft for outputting a shifted torque of the engine, a first planetary gear set including first, second, and third rotational elements, a second planetary gear set including fourth, fifth, and sixth rotational elements, a third planetary gear set including seventh, eighth, and ninth rotational elements, a fourth planetary gear set including tenth, eleventh, and twelfth rotational elements, and six control elements for selectively interconnecting the rotational elements and a transmission housing.