Engine Start Stop Control Using Steering Wheel Speed
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Solution Overview
Problem
Current engine start/stop systems in hybrid and micro-hybrid vehicles face challenges in accurately determining the driver's intent when activating the transmission gear shifter, leading to unintended engine auto-starts or auto-stops, which can reduce fuel economy and increase emissions.
Innovation Solution
A controller is programmed to inhibit engine auto-stopping if the steering wheel's rotational speed is less than a threshold when the gear shifter is activated, and to auto-stop the engine if the rotational speed is greater than the threshold, ensuring the engine remains operational during intended gear shifts while preventing premature auto-starts or auto-stops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine auto-stop system is activated to improve fuel economy, then fuel consumption is reduced, but the engine may stop during unintended gear shifts causing operational issues
Solution Approach 1:
The system performs preliminary detection of gear shifter activation status before executing the engine auto-stop command. By checking whether the gear shifter is in the process of being shifted (comparing current position with previous position), the system prevents engine stoppage during unintended gear shifts, thereby maintaining operational reliability while preserving fuel economy benefits during normal conditions.
2Speed
If the engine auto-start system is activated to ensure engine availability, then engine responsiveness is improved, but unnecessary auto-starts increase fuel consumption and emissions
Solution Approach 1:
The system uses feedback from the gear shifter position sensor to determine whether an engine auto-start is necessary. By continuously monitoring the gear shifter position and comparing it with the previous position, the system only prevents auto-start when a genuine gear shift is detected, otherwise allowing normal auto-start operation to maintain responsiveness while avoiding unnecessary fuel consumption.
3Measurement precision
If the system monitors steering wheel rotational speed to detect driver intent, then accuracy of gear shift detection is improved, but system complexity increases
Solution Approach 1:
The system repurposes the existing steering wheel rotational speed sensor, originally designed for steering control, to also detect gear shifter activation. By utilizing the multi-functionality of the rotational speed sensor and controller, the system achieves accurate gear shift detection without adding dedicated hardware, thereby improving measurement precision while minimizing increases in system complexity.
Data Source
AI summary
A vehicle start/stop method includes inhibiting auto-stopping an engine responsive to an engine auto-stop command, activating a transmission gear shifter, and a rotational speed of a steering wheel being less than a threshold; auto-stopping the engine responsive to the engine auto-stop command, activating the gear shifter, and the rotational speed being greater than the threshold; auto-starting the engine responsive to activating the gear shifter and the rotational speed being less than the threshold while the engine is auto-stopped; and inhibiting auto-starting the engine responsive to activating the gear shifter and the rotational speed being greater than the threshold while the engine is auto-stopped.