Planetary Gear Train for 10-Speed Automatic Transmission

Solution Overview

Problem

Conventional eight-speed automatic transmissions with multiple planetary gear sets and control elements increase vehicle weight and production costs, affecting fuel efficiency and power flow, while attempts to reduce weight, such as using dog clutches, can deteriorate shift feel and are not widely applicable.

Innovation Solution

A planetary gear train with four planetary gear sets and six control elements, including clutches and brakes, arranged to achieve ten forward speeds and one reverse speed, optimizing power delivery and fuel economy by reducing the number of internal parts and employing a specific arrangement of sun gears, planet carriers, and ring gears.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If more planetary gear sets and control elements are used to increase shift stages, then fuel economy and drivability are enhanced, but vehicle weight and production cost increase

Engineering Contradiction:

Improvefuel economyVSAvoidvehicle weight

Core Design Contradiction:

ProductivityVSWeight of moving object

Solution Approach 1:

The patent merges multiple planetary gear sets into a integrated structure where gear sets share common components. Specifically, the first and second planetary gear sets share a common ring gear, and the third and fourth planetary gear sets share another common ring gear, reducing the total number of independent parts while maintaining ten forward speed stages

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Individual components perform multiple functions across different speed stages. The control elements (clutches and brakes) are designed to engage different combinations of sun gears, planet carriers, and ring gears to achieve various gear ratios, allowing each component to serve multiple purposes across the ten forward speeds and reverse speed

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

If more planetary gear sets and control elements are used to increase shift stages, then fuel economy and drivability are enhanced, but production cost increases

Engineering Contradiction:

Improvefuel economyVSAvoidproduction cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent merges multiple planetary gear sets into a integrated structure where gear sets share common components. Specifically, the first and second planetary gear sets share a common ring gear, and the third and fourth planetary gear sets share another common ring gear, reducing the total number of independent parts while maintaining ten forward speed stages

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Individual components perform multiple functions across different speed stages. The control elements (clutches and brakes) are designed to engage different combinations of sun gears, planet carriers, and ring gears to achieve various gear ratios, allowing each component to serve multiple purposes across the ten forward speeds and reverse speed

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Weight of moving object

If dog clutches are used instead of wet-type control elements to reduce weight, then vehicle weight decreases, but shift feel deteriorates

Engineering Contradiction:

Improvevehicle weightVSAvoidshift feel

Core Design Contradiction:

Weight of moving objectVSEase of operation

Solution Approach 1:

The patent employs wet-type control elements (clutches and brakes) that utilize friction-based engagement rather than mechanical dog clutches. These control elements are designed with friction plates and discs that provide smooth, progressive engagement, sacrificing some weight for superior shift quality and driver comfort

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the engagement mechanism from rigid mechanical coupling (dog clutches) to friction-based soft engagement (wet clutches and brakes). This parameter change in the engagement method allows for controlled slip and gradual torque transfer, maintaining smooth shift feel while achieving weight reduction through optimized component design

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9970514B2Planetary gear train of automatic transmission for vehicle

Publication Date: 2018.05.15 HYUNDAI MOTOR CO LTD

AI summary

The present disclosure provides a planetary gear train of an automatic transmission for a vehicle including an input shaft, an output shaft, four planetary gear sets respectively having three rotational elements, and six control elements for selectively interconnecting the rotational elements and a transmission housing.