Dynamic Braking Threshold for Automatic Engine Stop
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Solution Overview
Problem
Existing vehicle engine systems face reduced fuel efficiency due to limited opportunities for automatic engine stopping, as they rely solely on high braking capacity, which is not optimal for varying vehicle operating conditions, especially when the vehicle is moving at different speeds.
Innovation Solution
The system dynamically adjusts electric assisted braking force thresholds based on vehicle speed, allowing the engine to stop more frequently by providing desired braking forces without storing excess electric charge, and maintains engine stopping even at lower braking forces when the vehicle is stationary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the highest levels of braking capacity are required for automatic engine stopping, then the vehicle braking performance is ensured, but the opportunities to automatically stop the engine are reduced
Solution Approach 1:
The patent applies dynamics by making the braking force threshold adjustable based on vehicle operating conditions, specifically vehicle speed. The controller dynamically selects between a first threshold (higher braking capacity) and a second threshold (lower braking capacity) depending on whether the vehicle is moving or stationary, allowing the system to adapt to different operational contexts and maximize engine stopping opportunities while ensuring adequate braking performance.
Solution Approach 2:
The patent changes the parameter of braking force threshold based on vehicle speed conditions. When the vehicle is moving, a first (higher) braking force threshold is applied to ensure safe stopping. When the vehicle is stationary, a second (lower) braking force threshold is applied, allowing engine stopping even with minimal braking capacity. This parameter change resolves the contradiction by allowing frequent engine stops without compromising braking safety.
2Speed
If a higher braking force is applied to stop the vehicle at a desired rate, then the vehicle stopping performance is improved, but the electric charge storage requirement increases
Solution Approach 1:
The system dynamically adjusts the braking force threshold based on vehicle speed. At higher speeds, a higher braking force threshold ensures safe stopping rates. At zero or low speeds, a lower threshold suffices, reducing the electrical charge requirement while maintaining adequate braking performance for engine stopping operations.
Solution Approach 2:
The patent changes the braking force threshold parameter based on vehicle operating conditions. By switching between a first threshold (for moving vehicles) and a second threshold (for stationary vehicles), the system optimizes the balance between stopping performance and electrical charge consumption, allowing engine stopping with minimal charge when the vehicle is already stationary.
3Loss of energy
If the engine is stopped more frequently to conserve fuel, then fuel efficiency is improved, but the braking force availability may be insufficient
Solution Approach 1:
The patent changes the braking force threshold parameter based on vehicle speed conditions. When the vehicle is moving, a higher first threshold ensures adequate braking force is available. When the vehicle is stationary, a lower second threshold allows engine stopping even with minimal braking force, since the vehicle needs only to remain stationary rather than stop from motion. This resolves the contradiction by allowing frequent fuel-saving engine stops without compromising braking reliability.
Solution Approach 2:
The system dynamically adapts the braking threshold to match operational requirements. The controller adjusts between first and second thresholds based on whether the vehicle is moving or stationary, ensuring braking force availability is sufficient for the current operational context while maximizing opportunities for fuel-saving engine stops.
Data Source
AI summary
Systems and methods for operating a vehicle that includes an engine that may be automatically stopped and started are described. In one example, an engine may be automatically stopped in response to an electric assisted braking threshold level that is adjusted responsive to vehicle speed so that opportunities to automatically stop an engine may be increased, thereby conserving fuel.