Driveline Disconnect Clutch Pre-positioning for Faster Engine Start
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Solution Overview
Problem
The driveline disconnect clutch in vehicles takes a significant time to close and transfer torque, increasing engine starting time and causing delayed vehicle response due to the need for a threshold pressure to be applied, which can lead to lower than expected vehicle performance.
Innovation Solution
Adjusting the driveline disconnect clutch pressure as a function of driver demand torque and engine pull-up torque to pre-position the clutch for faster closure and reduce engine starting time, allowing for quicker torque transfer when demand exceeds pull-up torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the driveline disconnect clutch is commanded closed from a full open position, then the engine can be started and torque can be transferred, but it takes nearly a second or longer for the clutch to begin transferring torque, increasing engine starting time and causing delayed vehicle response
Solution Approach 1:
The system performs preliminary action by increasing driveline disconnect clutch pressure when driver demand torque is increasing but less than engine pull-up torque, positioning the clutch closer to full closure before an engine start is actually needed. This pre-positioning reduces the time delay when the clutch needs to close rapidly for engine starting, as the pressure is already elevated rather than starting from zero or low pressure.
2Loss of time
If the driveline disconnect clutch pressure is increased to reduce closing time, then engine starting time is reduced, but driveline noise and vibration may increase during engine starting
Solution Approach 1:
The system applies dynamics by continuously adjusting driveline disconnect clutch pressure as a function of driver demand torque and engine pull-up torque. Rather than using a fixed high pressure that would cause noise and vibration, the pressure is dynamically modulated based on real-time operating conditions, allowing rapid closure when needed while minimizing harmful effects through controlled pressure application.
Solution Approach 2:
The system changes parameters by adjusting pressure application strategy based on the relationship between driver demand torque and engine pull-up torque. When driver demand torque is increasing but less than engine pull-up torque, pressure is increased to pre-position the clutch. This parameter change allows the system to achieve fast closure when needed while avoiding constant high pressure that would generate noise and vibration during normal operation.
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 reduces engine starting time, minimizes driveline noise and vibration, and maintains efficiency by ensuring the clutch has sufficient torque capacity without large pressure changes, enhancing vehicle responsiveness.
Implementation Method 1
The driveline disconnect clutch may be closed via hydraulic fluid applying pressure to plates of the driveline disconnect clutch
Data Source
AI summary
A method for operating a vehicle that includes a driveline disconnect clutch is described. In one example, the method includes adjusting a pressure of the driveline disconnect clutch as a function of an engine pull-up torque minus a driver demand torque when the pressure of the driveline disconnect clutch is between a torque stroke pressure and a hydraulic stroke pressure.