Engine Starting Device Selection via Torque Reserve Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for starting an internal combustion engine using electric machines face challenges in managing torque reserves effectively, particularly when the engine is stopped, as the electric machines have limited output torque capacity, and it is unclear which starting device, flywheel starter or ISG, is best suited for various operating conditions.
Innovation Solution
A method is developed to dynamically adjust the engine starting torque reserve based on the actual cumulative number of engine starts and vehicle operating conditions, allowing for the selection of either the flywheel starter or the ISG for engine starting, ensuring sufficient torque capacity and balancing wear across starting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric machine is used to start the engine, then the engine can be started reliably, but the torque capacity of the electric machine is limited and may not suffice under all operating conditions
Solution Approach 1:
The system segments the engine starting function by providing two separate starting devices: a flywheel starter for high-torque requirements and an integrated starter/generator (ISG) for normal operating conditions. This segmentation allows each device to be optimized for its specific function, resolving the contradiction between reliability and torque capacity limitations.
Solution Approach 2:
The system dynamically selects which starting device to use based on real-time operating conditions, cumulative start counts, and torque reserve availability. This dynamic adaptation allows the system to switch between devices optimally, ensuring reliable starting while managing the limited torque capacity of the electric machine.
2Power
If the flywheel starter is used for engine starting, then sufficient torque capacity is available, but wear on the flywheel starter increases
Solution Approach 1:
The control system dynamically manages the selection and usage of the flywheel starter based on operating conditions and cumulative start counts. By limiting flywheel starter usage to specific high-torque scenarios and switching to ISG for normal starts, the system maintains sufficient torque capacity when needed while reducing overall wear and extending durability.
Solution Approach 2:
The system changes the operational parameters of the flywheel starter by implementing a cumulative start counter and torque reserve thresholds. When the cumulative start count exceeds a threshold or torque reserve is insufficient, the system transitions away from flywheel starter usage, thereby managing wear while maintaining adequate torque capacity for critical starting events.
3Productivity
If the torque demand threshold for engine start is lowered, then the engine can be started more frequently, but the electric machine torque capacity may be depleted
Solution Approach 1:
The system implements feedback control by continuously monitoring the cumulative number of engine starts, torque reserve levels, and operating conditions. Based on this feedback, the control system dynamically adjusts the torque demand threshold and selects the appropriate starting device, allowing frequent starts when torque reserve is sufficient while preventing depletion when it is not.
Solution Approach 2:
The torque demand threshold is not fixed but dynamically adjusted based on real-time system state including cumulative start counts and torque reserve availability. This dynamic threshold adjustment enables the system to accommodate frequent starts when conditions permit while protecting against torque capacity depletion.
4Reliability
If the torque demand level is increased to ensure sufficient torque for engine start, then starting reliability improves, but driver demand torque may not be met
Solution Approach 1:
The system segments the torque provision function by using the flywheel starter for high-torque engine cranking when needed, thereby preserving the electric machine's torque capacity for meeting driver demand. This segmentation allows high reliability engine starting without compromising the torque available for propulsion.
Solution Approach 2:
The flywheel starter acts as an intermediary device that handles the high-torque requirement for engine cranking, allowing the electric machine to focus on meeting driver demand torque. This intermediary approach resolves the contradiction by providing a dedicated mechanism for engine starting that does not compete with the electric machine's propulsion function.
Data Source
AI summary
A method for operating a vehicle that includes an internal combustion engine that may be automatically stopped and started is described. In one example, selection of an engine starting device is based on a value of an engine starting torque reserve. The engine starting torque reserve may be dynamically adjusted so that life spans of engine starting devices may meet expectations.