Planetary Gear Train Shaft Arrangement for 10-Speed Transmission

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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 can deteriorate fuel efficiency and drivability.

Innovation Solution

A planetary gear train configuration with four single pinion planetary gear sets and six engagement elements, including clutches and brakes, is used to achieve at least ten forward speeds and one reverse speed, optimizing the arrangement of shafts and engagement elements to minimize parts while enhancing shift stages and stability.

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 shift stages and fuel efficiency are improved, but the device complexity, weight, and installability deteriorate

Engineering Contradiction:

Improveshift stagesVSAvoidnumber of parts

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent merges multiple planetary gear sets into a unified structure where four planetary gear sets share common shafts and engagement elements. The first and second planetary gear sets share the first shaft, while the third and fourth planetary gear sets share the second shaft, reducing the total number of independent components while achieving ten forward speeds and one reverse speed.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Engagement elements serve multiple functions across different planetary gear sets. The same clutches and brakes are used to control multiple planetary gear sets simultaneously, allowing a single engagement element to perform multiple locking and unlocking operations across different gear stages, thereby reducing the total number of engagement elements needed.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

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

Engineering Contradiction:

Improveshift stagesVSAvoidweight

Core Design Contradiction:

ProductivityVSWeight of moving object

Solution Approach 1:

The patent combines four planetary gear sets into a compact arrangement where multiple gear sets share common shafts and housing structures. This merging approach reduces the cumulative weight that would result from four completely separate planetary gear sets while maintaining the capability to achieve ten forward speeds and one reverse speed.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If the number of planetary gear sets is increased to achieve more shift stages, then the shift stages are improved, but the length and installability deteriorate

Engineering Contradiction:

Improveshift stagesVSAvoidlength

Core Design Contradiction:

ProductivityVSLength of moving object

Solution Approach 1:

The patent arranges planetary gear sets in a nested configuration where gear sets are positioned concentrically and share common rotational axes. The first and second planetary gear sets are arranged to share the first shaft, while the third and fourth planetary gear sets share the second shaft, creating a compact nested structure that minimizes the overall length of the transmission assembly.

Inventive Principle:

Principle #7Nested doll (Nesting)

4Device complexity

If dog clutches are used instead of wet-type control elements, then the device complexity is reduced, but the shift feel and driver comfort deteriorate

Engineering Contradiction:

Improvedevice complexityVSAvoidshift feel

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The patent employs wet-type control elements (clutches and brakes) that can be replaced as wear components rather than attempting to create a permanent, maintenance-free system. These engagement elements are designed as replaceable components that maintain smooth shift characteristics over their service life, prioritizing driver comfort and shift quality over long-term structural simplicity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS10274058B2Planetary gear train of automatic transmission for vehicle

Publication Date: 2019.04.30 HYUNDAI MOTOR CO LTD

AI summary

A planetary gear train is provided. The gear train includes input and output shafts and first to fourth planetary gear sets that respectively have first to third, fourth to sixth, seventh to ninth, and tenth to twelfth elements. A first shaft is connected with the first and fourth elements and selectively connected with the input shaft, a second shaft is connected with the sixth element and selectively connected with the input shaft, a third shaft is connected with the eighth element and the output shaft, a fourth shaft is connected with the second, fifth, and ninth elements, and a fifth shaft is connected with the third and eleventh elements. A plurality of shafts are each selectively connected to the transmission housing and connected to an element of the third and fourth planetary gear sets that is not connected with any of the first to seventh shafts.