Dual-Clutch Transmission Torque Splitting for Launch Heat Reduction
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Solution Overview
Problem
Conventional dual-clutch transmissions face inefficiencies due to high heat generation in clutches during vehicle launch, leading to reduced durability and performance, especially with wet clutches, and noise, vibration, and harshness issues with dry clutches.
Innovation Solution
A dual-clutch transmission assembly that splits engine torque between two layshafts using contemporaneously engaged clutches and duplicate gears, reducing heat generation and allowing for exclusive use of first gear launches for improved acceleration and reduced noise, vibration, and harshness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single clutch is used to transmit all engine torque during vehicle launch, then the transmission can achieve simple structure and fast response, but the clutch generates excessive heat leading to reduced durability and performance
Solution Approach 1:
The patent divides the single clutch into two separate clutches (first clutch and second clutch), each capable of independently transmitting torque. During vehicle launch, both clutches are engaged simultaneously to share the torque load, reducing heat generation in each clutch and improving durability.
2Temperature
If wet clutches are used with high volume coolant flow, then cooling effectiveness is improved, but pump size increases and parasitic losses increase reducing transmission efficiency
Solution Approach 1:
By segmenting the torque transmission into two clutches, the heat generation per clutch is reduced by approximately half. This allows wet clutches to operate with lower coolant flow rates, reducing pump size and parasitic losses while maintaining adequate cooling effectiveness.
3Loss of energy
If dry clutches are used with air-cooling, then transmission efficiency is improved by eliminating pump losses, but repeated launches lead to clutch overheating
Solution Approach 1:
The patent uses two dry clutches that share the torque load during launch. This segmentation reduces the thermal load on each clutch, allowing them to withstand repeated launches without overheating, while maintaining the efficiency benefits of dry clutch operation with air-cooling.
4Reliability
If clutch slip is limited to prevent overheating, then clutch durability is improved, but torque jerks occur and acceleration performance deteriorates
Solution Approach 1:
With two clutches sharing the torque load, each clutch experiences reduced stress and heat generation. This allows the transmission to maintain longer slip times during launch without risking clutch damage, thereby improving acceleration performance while avoiding torque jerks through smoother torque transfer.
5Temperature
If alternating first gear and second gear launches are used to cool clutches, then clutch overheating is prevented, but noise, vibration, and harshness increase
Solution Approach 1:
The patent enables both clutches to be engaged simultaneously during first gear launches, distributing the thermal load and allowing continuous use of first gear launches without alternating to second gear. This eliminates the noise, vibration, and harshness associated with alternating gear launches while still preventing clutch overheating through torque sharing.
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 solution results in a more efficient, durable, and better-performing transmission with reduced coolant flow requirements for wet clutches and fewer clutch failures for dry clutches, enabling longer slip times and improved acceleration.
Implementation Method 1
A first clutch is disposed between and interconnects the first input hub and the first layshaft. Accordingly, the first clutch selectively couples rotation of the first input hub with the first layshaft. A second clutch is disposed between and interconnects the second input hub with the second layshaft.
Implementation Method 2
Where the clutch is a wet clutch, cooling is achieved by high volume fluid flow through the clutch, which may reach up to 20 liters per minute.
Implementation Method 3
However, such dry clutches rely on less efficient air-cooling and repeated launches can lead to overheating of the clutch.
Data Source
AI summary
A dual-clutch transmission assembly is disclosed that splits the torque generated by an engine between first and second layshafts. A first input hub is connected to the first layshaft by a first clutch and a second input hub is connected to the second layshaft by a second clutch. A first gearset is carried on the first layshaft and a second gearset is carried on the second layshaft. The first gearset includes a primary first gear and the second gearset includes a duplicate first gear. The first and second layshafts receive torque from the transmission input shaft in response to contemporaneous engagement of the primary first gear, the duplicate first gear, and the first and second clutches, which can be used during vehicle launch to split the torque applied to the first and second clutches.