Multi-Plane Planetary Transmission for Low Range Torque

Solution Overview

Problem

Automobile manufacturers face challenges in improving fuel efficiency by increasing speed ratios in transmissions while also reducing the width of the engine compartment, particularly in transverse mounted powertrains which lack a low range mode due to the absence of a transfer case.

Innovation Solution

The described transmission systems utilize arrangements of planetary gear sets and couplers to achieve up to eight forward speed ratios and one reverse speed ratio, with two planetary gear sets in a single axial plane, allowing for a small tooth number ratio that maintains favorable spacing and enables a special purpose low range mode similar to that provided by a transfer case.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the number of gear sets and clutches is increased to provide more speed ratios, then fuel efficiency is improved, but the transmission length increases

Engineering Contradiction:

Improvefuel efficiencyVSAvoidtransmission length

Core Design Contradiction:

Use of energy by moving objectVSLength of moving object

Solution Approach 1:

The patent employs nested planetary gear sets where inner and outer planetary gears are arranged concentrically around a common sun gear. This nesting allows multiple gear reduction stages to be contained within a compact radial space, achieving multiple speed ratios without proportionally increasing the transmission's axial length

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent transitions from a single-plane gear arrangement to a multi-plane three-dimensional configuration. By stacking planetary gear sets in different axial planes and using carrier connections, the patent achieves multiple speed ratios in a compact axial space, effectively moving the problem from one-dimensional length extension to three-dimensional space utilization

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If the transmission is made longer to accommodate more gear sets, then more speed ratios are achieved, but the engine compartment width constraint is violated

Engineering Contradiction:

Improvenumber of speed ratiosVSAvoidtransmission length

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent employs nested planetary gear sets where inner and outer planetary gears are arranged concentrically around a common sun gear. This nesting allows multiple gear reduction stages to be contained within a compact radial space, achieving multiple speed ratios without proportionally increasing the transmission's axial length

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent transitions from a single-plane gear arrangement to a multi-plane three-dimensional configuration. By stacking planetary gear sets in different axial planes and using carrier connections, the patent achieves multiple speed ratios in a compact axial space, effectively moving the problem from one-dimensional length extension to three-dimensional space utilization

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of operation

If transverse powertrains used a longer transmission to achieve low range mode, then torque control would be improved, but the engine compartment width constraint would be violated

Engineering Contradiction:

Improvelow range mode capabilityVSAvoidtransmission length

Core Design Contradiction:

Ease of operationVSLength of stationary object

Solution Approach 1:

The patent designs the planetary gear set arrangement to serve multiple functions: it provides multiple forward speed ratios for fuel efficiency, enables low range mode for torque control, and maintains reverse capability. The same nested gear structure and clutch/brake combinations achieve all these functions without requiring separate transmission extensions

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent transitions from a single-plane gear arrangement to a multi-plane three-dimensional configuration. By stacking planetary gear sets in different axial planes and using carrier connections, the patent achieves multiple speed ratios in a compact axial space, effectively moving the problem from one-dimensional length extension to three-dimensional space utilization

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS8882628B2Multiple speed transmission

Publication Date: 2014.11.11 FORD GLOBAL TECH LLC

AI summary

Four planetary gear sets, three rotating clutches, and two brakes can be arranged to produce eight forward speed ratios and a reverse speed ratio. The first and fourth gear sets can be substantially coplanar with each other, and the second and third gear sets can be substantially coplanar with each other. The lowest forward speed ratio could be suitable for use as a special purpose low range ratio, while the remaining seven forward ratios can provide adequate span for normal driving.