Dual-Clutch Engine Shutdown for Low-NVH Powertrains
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Solution Overview
Problem
Existing methods for turning off internal combustion engines result in high noise, vibration, and harshness (NVH), which are costly and time-consuming to address, and do not provide a satisfactory user experience, especially during engine stopping.
Innovation Solution
A method involving a dual clutch transmission system where the engine is controlled to an idling state, with clutches in open positions, and then engaged with pre-selected gears to capture engine inertia through simultaneous torque transfer, reducing NVH by converting inertia into heat, thus enabling a controlled engine stop with reduced vibrations and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fuel cut is used to turn off the internal combustion engine, then the engine stopping time is reduced, but noise and vibration increase significantly
Solution Approach 1:
The clutch arrangement acts as an intermediary mechanism between the engine and transmission. By controlling the clutch disengagement process, the engine can be stopped without directly connecting to the transmission gears, thereby reducing noise and vibration while maintaining acceptable stopping time. The clutch serves as a buffer that mediates the stopping process.
Solution Approach 2:
The method engages pre-selected gears before engine shutdown. This preliminary gear engagement ensures that the transmission is ready to receive power immediately after engine restart, eliminating the need for gear shifting during idle periods and reducing overall noise and vibration exposure to the driver.
2Object-generated harmful factors
If extensive modifications are made to reduce NVH (such as modifying flywheel, firewall, and cabin insulation), then NVH performance improves, but manufacturing costs increase
Solution Approach 1:
The invention converts the potential harmful effect of engine stopping into a beneficial controlled process. By using the clutch arrangement to manage the stopping sequence, the system transforms what would normally be a high-NVH event into a controlled, low-NVH process, eliminating the need for expensive NVH mitigation modifications.
Solution Approach 2:
The method changes the operational parameters of the clutch arrangement during engine shutdown. By adjusting clutch engagement/disengagement timing and sequence, the system optimizes the stopping process to minimize noise and vibration generation, achieving NVH reduction through control strategy rather than physical modifications.
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
This approach significantly reduces engine stopping time and NVH, improving the user experience and allowing for cost-effective powertrain design with lower manufacturing costs by minimizing the need for extensive modifications in components like flywheel and cabin insulation.
Implementation Method 1
stopping the internal combustion engine by at least partly closing the first clutch and the second clutch for simultaneously introducing torque transfer to the first clutch and the second clutch into a transmission tie-up state for a controlled engine stop, wherein engine inertia of the internal combustion engine is captured in the first clutch and the second clutch
Data Source
AI summary
A method for turning off an internal combustion engine (ICE) where a clutch arrangement has first and second clutches that respectively couple the ICE to first and second input shafts of a transmission. The input shafts are drivingly connected to first and second sets of gears, respectively. The sets of gears are connected to an output shaft of the transmission. The method includes: controlling the ICE in an idling state when the vehicle is in standstill, wherein the clutches are in open positions; engaging the first input shaft with a first pre-selected gear, and engaging the second input shaft with a second pre-selected gear; initiating an engine turning off command; stopping the ICE by at least partly closing the clutches for simultaneously introducing torque transfer to the clutches into a transmission tie-up state for a controlled engine stop, wherein engine inertia of the ICE is captured in the clutches.