Automatic Powershift Transmission Clutch Layout

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Solution Overview

Problem

Conventional vehicle transmissions experience slow gear changes and torque loss due to the need to disengage and re-engage clutches, leading to inefficiencies and increased fuel consumption, particularly in high-speed applications.

Innovation Solution

An automatic powershift transmission design with multiple clutches and intermediate shafts allows for seamless gear changes without torque loss, utilizing a layout where clutches are strategically positioned between the input and output shafts, and including a reverse shaft for efficient gear shifting, reducing the time required for gear changes and maintaining unbroken torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional syncromesh gearboxes disengage forward or reverse clutch to change gears, then gear selection is achieved, but torque loss occurs and gear change time increases

Engineering Contradiction:

Improvegear selection capabilityVSAvoidtorque loss

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The transmission system is divided into multiple independent clutch assemblies (first forward clutch, second forward clutch, reverse clutch) that can operate independently. This segmentation allows one clutch to disengage while another engages, enabling seamless gear changes without complete torque interruption. The multiple clutch segments work in coordination to maintain continuous power flow through different gear paths.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The transmission system pre-positions multiple clutch assemblies and their associated gear paths before gear changes are needed. The first and second forward clutches are both ready to engage their respective gear paths, allowing the system to switch between gears by simply changing which clutch is engaged, rather than having to reconfigure the entire transmission during the shift.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If multi-plate clutches are used for powershift gearboxes, then torque continuity is maintained, but power losses increase due to heat and inertia drag

Engineering Contradiction:

Improvetorque continuityVSAvoidpower loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent extracts the essential function of torque continuity from the multi-plate clutch system while removing the source of power losses. Instead of using multi-plate clutches that generate heat and drag, the invention uses simpler clutch assemblies that achieve torque continuity through their engagement/disengagement timing and the constant rotation of gear elements, eliminating the need for oil churning and reducing thermal losses.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potential harm of clutch disengagement (torque interruption) into a benefit by using multiple clutches that can overlap in their operation. The system accepts that individual clutches will disengage and engage, but designs the system so that this switching action maintains overall torque continuity while avoiding the continuous power losses associated with multi-plate clutch operation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If clutches are located in line with alternate lay shafts in twin clutch gearboxes, then gear ratios are provided on alternate lay shafts, but gearbox length increases

Engineering Contradiction:

Improvegear ratio provisionVSAvoidgearbox length

Core Design Contradiction:

Adaptability or versatilityVSLength of moving object

Solution Approach 1:

The patent rearranges the transmission components from a longitudinal arrangement (clutches in line with alternate lay shafts) to a transverse arrangement where clutches are positioned between the input and output shafts. This dimensional change allows the same gear ratio functionality to be achieved in a more compact longitudinal footprint, effectively trading longitudinal space for transverse space.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Instead of placing clutches at the ends of alternate lay shafts in the conventional arrangement, the patent inverts the approach by positioning the clutches between the input and output shafts. This inversion allows the clutch operating points to be strategically located where they can control multiple gear paths simultaneously, reducing the overall gearbox length while maintaining the ability to provide multiple gear ratios.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS8250938B2Vehicle transmission

Publication Date: 2012.08.28 JCB TRANSMISSIONS

AI summary

An automatic powershift vehicle transmission comprising an input shaft; an output shaft; first and second intermediate shafts parallel to the input shaft; a lay shaft parallel to the output shaft; gearing providing first, second, third and fourth forward driving paths from the input shaft to the output shaft; a first clutch and a second clutch between the ends of the input shaft to establish driving connections; a third clutch for establishing the first or third forward driving path when the first clutch is operative; and a fourth clutch for establishing the second or fourth forward driving path when the second clutch is operative.