Vehicle Powertrain Control Strategies for Fuel Efficiency
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Solution Overview
Problem
Existing methods for operating motor vehicles with internal combustion engines do not effectively optimize fuel efficiency and engine responsiveness across all driving situations, particularly when no driving force is required.
Innovation Solution
A method and drive system that employs multiple control strategies based on vehicle speed, including stationary start-stop, rolling, coasting, and creeping modes, utilizing a control device to manage frictional engagement in the drivetrain and engine operation, allowing for adaptive switching between these modes without complex energy system adaptations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the drive motor is switched off or operated at idle speed to reduce fuel consumption, then fuel efficiency improves, but engine responsiveness deteriorates
Solution Approach 1:
The system dynamically switches between different operating modes (stationary start-stop mode, rolling stationary start-stop mode, coasting mode, creeping mode) based on real-time vehicle speed and driving conditions. This dynamic adaptation allows the engine to remain off during low-speed stationary conditions while being quickly restartable when needed, thus reducing fuel consumption without permanently compromising responsiveness.
Solution Approach 2:
The control device pre-conditions the engine for quick restart by maintaining readiness systems (starter motor, fuel delivery, ignition) even when the engine is switched off. This preliminary preparation ensures that when the engine needs to restart, it can do so rapidly, preserving responsiveness while enjoying the fuel savings of being off during idle periods.
2Use of energy by moving object
If frictional engagement in the drivetrain is interrupted to reduce fuel consumption, then fuel efficiency improves, but drive force transmission deteriorates
Solution Approach 1:
The clutch or frictional engagement mechanism is dynamically controlled based on operating mode. In coasting mode, frictional engagement is interrupted to reduce parasitic losses and improve fuel efficiency. When driving force is required, the system quickly re-engages the frictional connection, ensuring that drive force transmission is restored when needed. This dynamic control resolves the contradiction by having frictional engagement only when necessary.
Solution Approach 2:
The drivetrain is segmented into controllable sections with the frictional engagement mechanism (clutch) acting as a decoupling element. This segmentation allows the drive motor to be isolated from the drivetrain when fuel efficiency is prioritized (coasting mode), while enabling quick reconnection when drive force is needed, thus resolving the contradiction between fuel efficiency and drive force transmission.
3Use of energy by moving object
If multiple control strategies are implemented to optimize fuel efficiency across all driving situations, then fuel consumption improves, but device complexity increases
Solution Approach 1:
The control device is designed as a universal controller that handles multiple functions: selecting between stationary start-stop mode, rolling stationary start-stop mode, coasting mode, and creeping mode based on vehicle speed and driving conditions. This single multi-functional control unit manages all mode transitions and clutch control, avoiding the need for separate control systems for each function, thus limiting the increase in complexity while achieving comprehensive fuel optimization.
Solution Approach 2:
The patent combines the selection logic for multiple operating modes and the clutch control functions into a unified control strategy. Instead of having separate control systems for engine management, clutch control, and mode selection, these functions are merged into an integrated control approach that makes decisions based on a unified assessment of vehicle speed and driving conditions, thereby reducing overall 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
The method reduces fuel consumption while maintaining responsive engine behavior by strategically selecting driving modes based on vehicle speed and speed control actuation, optimizing fuel efficiency without impairing the drive system's response.
Implementation Method 1
a clutch (22) for frictional engagement between the drive motor (20) and the at least one driven wheel (4)
Data Source
AI summary
A method of operating a vehicle powertrain, includes: sensing a vehicle speed; selecting a plurality of control strategies; activating one of the plurality of control strategies, the control strategy including: (i) operating the vehicle in a stationary start-stop mode when the vehicle speed is below a first threshold; and (ii) operating the vehicle in a rolling stationary start-stop mode when the vehicle speed is above the first threshold but below a second threshold.