Dual-Clutch Transmission Chamber Layout for Off-Road Lubrication

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Solution Overview

Problem

Dual-clutch transmissions (DCTs) have not been widely adopted in off-road vehicles due to high manufacturing costs and packaging issues, and maintaining efficient lubrication of their components is challenging in vehicles with limited space.

Innovation Solution

A dual-clutch transmission system with an internal dividing wall and a transmission fluid distribution system that includes a primary pump, fluid channels, fluid spraying devices, and a heat exchanger to ensure balanced pressure and efficient lubrication, while incorporating a rotary vane pump and suction pumps to manage fluid flow and cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a dual-clutch transmission is implemented in an off-road vehicle, then shifting performance and efficiency are improved, but manufacturing costs and packaging complexity increase

Engineering Contradiction:
Improveshifting performanceVSAvoidpackaging complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The transmission housing is divided into multiple chambers (first chamber, second chamber, third chamber) separated by internal dividing walls. This segmentation allows independent lubrication zones for different clutch assemblies and gear trains, enabling compact packaging while maintaining the complex dual-clutch functionality required for improved shifting performance.

Inventive Principle:
Principle #1Segmentation

2Productivity

If a dual-clutch transmission is implemented in an off-road vehicle, then shifting performance and efficiency are improved, but manufacturing costs increase

Engineering Contradiction:
Improveshifting performanceVSAvoidmanufacturing cost
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The transmission housing serves multiple functions simultaneously: it provides structural support, defines lubrication chambers, contains seals and gaskets, and facilitates fluid distribution through integrated passages. This multi-functionality reduces the number of separate components needed, simplifying manufacturing while maintaining the complex dual-clutch transmission design for improved shifting performance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Volume of moving object

If the size of the DCT is limited by available space, then packaging is improved, but efficient lubrication of components becomes difficult to implement

Engineering Contradiction:
Improvetransmission sizeVSAvoidlubrication efficiency
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

A dedicated lubrication system with transmission fluid distributed through controlled passages and channels acts as an intermediary to deliver lubrication precisely to clutch plates, gears, and bearings. This systematic approach ensures adequate lubrication in the compact transmission design, maintaining reliability despite the reduced size and limited space for traditional lubrication methods.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The lubrication system uses hydraulic principles with transmission fluid pumped through controlled passages and channels to deliver pressurized lubrication to critical components. This hydraulic lubrication approach ensures efficient oil delivery to all moving parts within the compact transmission housing, maintaining component reliability despite the limited space available.

Inventive Principle:
Principle #29Pneumatics and hydraulics

4Reliability

If transmission fluid is distributed throughout the transmission, then lubrication is improved, but device complexity increases

Engineering Contradiction:
ImprovelubricationVSAvoidfluid distribution system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The lubrication system merges multiple functions into integrated components: the transmission housing itself contains lubrication passages, the pump is integrated into the housing structure, and fluid distribution channels are built into the dividing walls. This consolidation reduces the number of separate lubrication components while ensuring comprehensive lubrication coverage, improving reliability without proportionally increasing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively addresses packaging and cost issues, providing efficient lubrication and cooling for DCT components, enhancing performance and reliability in off-road vehicles.

Implementation Method 1

a primary pump fluidly connected to the fluid tank and to the first and second chambers, the primary pump being configured to pump transmission fluid to the first and second chambers

Methodology Applied
Scientific EffectPump: Pump

Implementation Method 2

a heat exchanger fluidly connected to the primary pump and configured to absorb heat from transmission fluid received from the primary pump

Methodology Applied
Scientific EffectHeat exchanger: Heat Exchanger

Implementation Method 3

an air separator disposed in the separator compartment and configured to separate air from transmission fluid

Methodology Applied
Scientific EffectAir separator: Cyclone Separation

Implementation Method 4

the internal dividing wall defines at least one air hole disposed in an upper portion of the internal dividing wall for balancing a pressure within the first chamber with a pressure within the second chamber

Methodology Applied
Scientific EffectPressure balancing: Pascal's Law

Data Source

PatentEP4441396B1Dual-clutch transmission
Publication Date: 2025.12.31 BRP-ROTAX GMBH & CO KG
  • EP4441396B1 patent drawingFigure 1
  • EP4441396B1 patent drawingFigure 2
  • EP4441396B1 patent drawingFigure 3A

AI summary

A transmission for a vehicle (20) includes: an input shaft (122) for connection to an internal combustion engine (52) of the vehicle (20); a gear (605) shaft (122, 199, 400A, 400B) selectively operatively connected to the input shaft (122); a clutch selectively actuatable to transmit motion between the input shaft (122) and the gear (605) shaft (122, 199, 400A, 400B) for selectively operating the transmission in one of a plurality of transmission gears (600); an output shaft (740) operatively connected to the gear (605) shaft (122, 199, 400A, 400B) at least in part by the transmission gears (600); and a transmission housing (102) at least partly enclosing the input shaft (122), the transmission gears (600), the clutch and the output shaft (740). An internal dividing wall (506, 510) defines first and second chambers (350A, 502), the internal dividing wall (506, 510) being configured to limit flow of transmission fluid between the first and second chambers (350A, 502). The input shaft (122) and the clutch are disposed within the first chamber (350A, 350B, 508). The transmission gears (600) and the output shaft (740) are disposed within the second chamber (350A, 350B, 508).