Engine Stop-Start Control via Manifold Pressure and Speed Monitoring
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Solution Overview
Problem
In motor vehicles equipped with stop-start technology, there is a challenge in quickly restarting the engine after a 'change of mind' event without damaging the starter motor or ring gear, due to the non-linear speed profile of a stopping engine and the risk of engaging the starter motor during reverse rotation.
Innovation Solution
A method that involves initiating engine shut-down by closing the throttle valve and restarting the engine using a starter device when the engine speed is within predefined limits and the absolute pressure in the inlet manifold is below a certain limit, thereby reducing the likelihood of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the starter motor is engaged before the engine has completely stopped rotating to reduce restart delay, then the engine can be restarted more quickly, but there is a risk of damage to the starter motor or ring gear due to non-linear speed profile and reverse rotation
Solution Approach 1:
The control system performs preliminary assessment of engine speed and direction before engaging the starter motor. By checking whether the engine speed is within the predefined range and rotation direction is correct, the system prepares the restart condition in advance, allowing the starter to be engaged at the optimal moment without causing damage while minimizing restart delay.
Solution Approach 2:
The control system continuously monitors engine speed and rotation direction, using this feedback to determine the appropriate timing for starter motor engagement. The feedback mechanism ensures that the starter is only engaged when safe conditions are met, resolving the contradiction between quick restart and damage prevention.
2Reliability
If the engine is waited until zero speed before starter engagement to ensure safety, then starter motor damage risk is minimized, but vehicle performance and safety are impacted due to increased restart delay
Solution Approach 1:
The invention changes the parameter for starter engagement from a fixed zero-speed condition to a dynamic range-based condition. By defining a predefined speed range and direction criteria, the system allows engagement at non-zero speeds that are still safe, thus improving response time while maintaining reliability.
Solution Approach 2:
The control system dynamically adjusts the engagement decision based on real-time engine speed and direction conditions. Rather than using a static zero-speed threshold, the system adapts to the actual engine state, enabling safer and faster restart decisions that respond to changing conditions.
3Device complexity
If a fixed zero-speed threshold is used for starter engagement, then the control logic is simple, but it cannot accommodate the non-linear speed profile and may cause damage or unnecessary delays
Solution Approach 1:
The control system performs preliminary checks of multiple parameters (speed range and rotation direction) before engaging the starter. This preliminary assessment approach maintains relatively simple control logic while significantly improving reliability by ensuring safe engagement conditions are met before activation.
Data Source
AI summary
A method of controlling the stopping and starting of an engine is disclosed in which, during an engine shut-down period, if a signal indicative of a request for restarting the engine is generated, the engine 1000 is restarted if the engine speed (N) is within a predefined speed range and the absolute pressure (MAP) in a manifold of the engine is below a predefined limit MAPlim.