Disconnect Clutch Stroke Control for Faster Hybrid Engine Start
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Solution Overview
Problem
The driveline disconnect clutch (DCC) in hybrid vehicles faces a tradeoff between engine start time and fuel efficiency, with actuation lag leading to decreased vehicle performance during transitions from electric to engine power due to its state management.
Innovation Solution
A controller adjusts the DCC state based on estimated driver demand power, using historical and crowdsourced data, vehicle density, and route characteristics to minimize actuation lag and optimize fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the DCC is kept in an open state to reduce drag and improve fuel efficiency, then fuel economy is improved, but engine start time increases and vehicle performance during transitions deteriorates
Solution Approach 1:
The controller performs preliminary action by stroking the DCC in advance when driver demand power exceeds the engine pull-up threshold. This anticipatory engagement prepares the clutch for rapid engine start without maintaining continuous engagement, thus improving fuel efficiency while reducing engine start time when needed.
Solution Approach 2:
The DCC state is made dynamic by continuously adjusting between open and stroked positions based on real-time comparison of driver demand power and engine pull-up threshold. This dynamic adaptation allows the system to optimize between fuel efficiency and engine start time according to actual driving conditions.
2Productivity
If the DCC is stroked to reduce actuation lag and improve vehicle performance during transitions, then engine start time is reduced, but fuel efficiency decreases due to increased drag
Solution Approach 1:
The controller applies preliminary action by stroking the DCC only when driver demand power exceeds the engine pull-up threshold. This conditional preliminary engagement prepares the system for rapid response without unnecessary continuous engagement, thus improving vehicle performance during transitions while minimizing fuel efficiency loss.
Solution Approach 2:
The DCC state parameter is changed dynamically based on the comparison between driver demand power and engine pull-up threshold. By adjusting the clutch engagement parameter (open vs. stroked) according to power demand conditions, the system optimizes the balance between vehicle performance during transitions and fuel efficiency.
3Speed
If the DCC is frequently adjusted between states to respond to changing driver demand, then vehicle responsiveness is improved, but device complexity and control difficulty increase
Solution Approach 1:
The controller uses feedback by continuously monitoring driver demand power and comparing it with the engine pull-up threshold. This simple feedback mechanism determines DCC state adjustments, improving vehicle responsiveness while keeping control logic relatively simple and manageable.
Solution Approach 2:
The control system manages complexity by focusing on a single critical parameter change - the DCC state (open or stroked) - which is determined by comparing two key parameters (driver demand power and engine pull-up threshold). This parameter-based control approach improves responsiveness while avoiding excessive system complexity.
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 actuation lag and enhances vehicle performance during transitions by anticipating driver demands, balancing fuel efficiency and engine start time.
Implementation Method 1
pressurizing a driveline disconnect clutch (DCC) to a touch point of the DCC
Data Source
AI summary
Methods and systems are provided for adjusting a state of a driveline disconnect clutch (DCC) of a hybrid vehicle to either maximize fuel efficiency or reduce time to engine start, when the hybrid vehicle is being operated under engine-off conditions. In one embodiment, a controller of the vehicle estimates a modified driver demand power at an upcoming location on a route of the vehicle, and adjusts the DCC to a fully depressurized state to maximize the fuel efficiency when the modified driver demand power is lower, and pressurizes the DCC to a touch point to reduce the time to engine start when the modified driver demand power is higher. The modified driver demand power may be estimated by the controller by applying multiplication factors to a vehicle-weight-based baseline driver demand power, where the multiplication factors are calculated based on vehicle density of traffic and route characteristics.