Four-Planetary Gear Transmission for Multi-Step Shifting

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Solution Overview

Problem

Existing automatic transmissions face challenges in increasing fuel efficiency and reducing weight and manufacturing costs while maintaining power transmission efficiency, especially when implementing multiple steps of shifting, due to the increased number of parts required.

Innovation Solution

A transmission system utilizing four planetary gear sets with three rotary elements each, along with a plurality of friction members and clutches, allows for selective connection and disconnection of rotary elements to achieve multiple gear ratios with fewer parts, enabling efficient shifting and improved fuel efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the shift ranges increase to improve fuel efficiency through multiple steps of shifting, then fuel efficiency is improved, but the number of parts in the automatic transmission increases making it 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 components such as the input shaft, output shaft, and transmission case. This consolidation allows the system to achieve multiple shift ranges (improving fuel efficiency) without proportionally increasing the number of discrete parts, as shared components serve multiple functions across different gear sets.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The planetary gear sets are designed with universal components that serve multiple functions. For example, the input shaft connects to multiple planetary gear sets, the transmission case serves as both a structural housing and a reaction member for multiple gear sets, and friction members (clutches and brakes) control multiple rotary elements across different gear sets. This multi-functionality enables the system to achieve complex shifting patterns without requiring dedicated components for each shift range.

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 of the automatic transmission increases

Engineering Contradiction:

Improvefuel efficiencyVSAvoidweight of transmission

Core Design Contradiction:

Use of energy by moving objectVSWeight of stationary object

Solution Approach 1:

The transmission system merges multiple planetary gear sets into a compact arrangement where gear sets share common components including the input shaft, output shaft, and transmission case. This consolidation reduces the overall weight compared to having separate gear sets for each shift range, as shared components eliminate redundant mass while still enabling multiple shift ranges for improved fuel efficiency.

Inventive Principle:

Principle #5Merging (Combining)

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 consolidates multiple planetary gear sets into a single integrated transmission system where components are shared across gear sets. This merging reduces the total number of parts that need to be manufactured and assembled, thereby lowering manufacturing costs while still achieving multiple shift ranges for improved fuel efficiency.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The design employs universal components that serve multiple functions across different gear sets and shift ranges. For example, friction members (clutches and brakes) control multiple rotary elements, and the transmission case serves as both structural housing and reaction member. This multi-functionality reduces the variety of unique parts that need to be manufactured, simplifying the manufacturing process and reducing costs while maintaining the capability for multiple shift ranges.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Adaptability or versatility

If the number of parts increases to achieve multiple steps of shifting, then multiple gear ratios are achieved, but power transmission efficiency deteriorates

Engineering Contradiction:

Improvemultiple gear ratiosVSAvoidpower transmission efficiency

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The transmission system merges multiple planetary gear sets into a compact integrated structure where power flows through shared components (input shaft, output shaft, transmission case) rather than through multiple separate transmission paths. This reduces the number of power transmission interfaces and potential loss points, maintaining high power transmission efficiency while still achieving multiple gear ratios through the coordinated operation of merged gear sets.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9765855B2Transmission for vehicles

Publication Date: 2017.09.19 HYUNDAI MOTOR CO LTD

AI summary

A transmission for vehicles may include a first planetary gear set, a second planetary gear set, a third planetary gear set, and a fourth planetary gear set each of the first, second and third planetary gear sets including three rotary elements; and a plurality of friction members, wherein the friction members are connected to at least one of the rotary elements of the planetary gear sets and control rotation of the rotary elements.