Four-Planetary Gear Transmission for Multi-Step Shifting

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Solution Overview

Problem

Automatic transmissions with increased shift ranges face challenges in manufacturing cost, weight, and power transmission efficiency due to the increased number of parts, making it difficult to achieve maximum fuel efficiency while maintaining vehicle driving comfort.

Innovation Solution

A transmission system utilizing four planetary gear sets with three rotary elements each, along with a plurality of friction members, allows for selective connection and disconnection of rotary elements through clutches, enabling multiple steps of shifting and improving fuel efficiency by operating within a low RPM range of the engine.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the shift ranges increase to improve fuel efficiency, then fuel efficiency is improved, but the number of parts increases making the transmission difficult to mount and increasing manufacturing cost and weight

Engineering Contradiction:

Improvefuel efficiencyVSAvoidnumber of parts

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent merges multiple planetary gear sets (first, second, third, and fourth planetary gear sets) into a single integrated transmission system where gear sets share common rotary elements and clutches. This consolidation achieves multiple shift ranges through coordinated operation of shared components rather than requiring separate, independent gear trains for each range.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The planetary gear sets and clutches serve multiple functions simultaneously. For example, the first carrier serves as both a rotary element in the first planetary gear set and is selectively connectable to the second ring gear and fourth sun gear. The same clutch controls multiple connection paths, enabling a single component to perform multiple shifting functions across different gear ranges.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Use of energy by moving object

If the shift ranges increase to improve fuel efficiency, then fuel efficiency is improved, but the weight increases

Engineering Contradiction:

Improvefuel efficiencyVSAvoidweight

Core Design Contradiction:

Use of energy by moving objectVSWeight of moving object

Solution Approach 1:

The transmission system combines multiple planetary gear sets with shared rotary elements (sun gears, carriers, ring gears) and common clutch mechanisms. This merging approach achieves multiple shift ranges without requiring proportionally more components, thereby controlling weight while maintaining fuel efficiency benefits.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The planetary gear sets are arranged in a nested configuration where the first, second, third, and fourth planetary gear sets are positioned sequentially with shared rotary elements. The first carrier is selectively connectable to components in subsequent gear sets, creating a compact nested structure that minimizes weight while enabling multiple shift ranges.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Use of energy by moving object

If the shift ranges increase to improve fuel efficiency, then fuel efficiency is improved, but the manufacturing cost increases

Engineering Contradiction:

Improvefuel efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent merges multiple planetary gear sets into a single integrated transmission system where components are shared across gear sets. This consolidation reduces the total number of parts that need to be manufactured and assembled, thereby controlling manufacturing cost while achieving multiple shift ranges for improved fuel efficiency.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The clutches and rotary elements serve multiple functions across different gear sets and shift ranges. For example, the first carrier is selectively connectable to the second ring gear and fourth sun gear through the same clutch mechanism, enabling a single component to control multiple shifting operations, which simplifies manufacturing and reduces cost.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Use of energy by moving object

If the number of parts increases to achieve multiple steps of shifting, then fuel efficiency is improved, but power transmission efficiency deteriorates

Engineering Contradiction:

Improvefuel efficiencyVSAvoidpower transmission efficiency

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The planetary gear sets are merged into an integrated system with shared rotary elements and clutch mechanisms, reducing the number of separate power transmission paths. This consolidation minimizes energy losses at connection points while maintaining multiple shift ranges for fuel efficiency improvement.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9791021B2Transmission for vehicle

Publication Date: 2017.10.17 HYUNDAI MOTOR CO LTD

AI summary

A transmission for a vehicle may include an input shaft, an output shaft, a first planetary gear set, a second planetary gear set, a third, planetary gear set, a fourth planetary gear set, provided to transfer a torque between the input shaft and the output shaft, and friction members, wherein each of the first, second, third, and fourth planetary gear sets includes three rotary elements and three of the friction members are each selectively connected to at least one of the at least three rotary elements of the first, second, third, and fourth planetary gear sets and control rotation of the rotary elements to achieve gear ratios of ten or more steps of forward shifting and one step of reverse shifting in a vehicle.