Intermittent Engine Restart via Speed Threshold Control
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Solution Overview
Problem
Current vehicle stop/start systems require the engine to come to a complete stop before restarting, leading to delays when the operator attempts to restart the vehicle before the engine has reached 0 rpm, causing operator frustration and reducing vehicle performance.
Innovation Solution
The system determines if stop/start enablement conditions are met and initiates an engine shutdown, allowing for a first intermittent restart sequence when the engine speed is above a threshold and a second intermittent restart sequence when the engine speed is greater than 0 but below the threshold, using a controller and engine speed sensor to manage fuel delivery and restart the engine without waiting for complete stop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is required to come to a complete stop before restarting, then the restart sequence is simplified and reliable, but the delay between operator request and engine restart increases causing operator frustration
Solution Approach 1:
The system initiates the restart sequence before the engine speed reaches zero by detecting when engine speed falls below a predetermined threshold. The controller prepares the restart conditions (fuel injection, ignition timing) in advance while the engine is still rotating, so that when the operator requests restart, the engine can immediately resume operation without waiting for complete stop. This preliminary preparation of restart conditions resolves the contradiction by eliminating the time delay while maintaining reliability through controlled threshold-based activation.
2Loss of time
If the engine restarts before reaching 0 rpm, then the delay is reduced and operator satisfaction improves, but the complexity of controlling the restart sequence increases
Solution Approach 1:
The system uses engine speed as a critical parameter to control the restart sequence. When the engine speed threshold is detected (below predetermined threshold but above zero), the controller automatically initiates the restart conditions. This parameter-based control simplifies the complexity by using a clear, measurable threshold criterion rather than complex timing or multiple sensor inputs. The threshold parameter provides a straightforward trigger point that balances early restart capability with operational safety.
3Productivity
If the engine is allowed to restart at any speed above 0 rpm, then operator response time is minimized, but the risk of improper restart conditions increases
Solution Approach 1:
The controller continuously monitors engine speed and uses this feedback to determine when to initiate the restart sequence. The feedback mechanism compares real-time engine speed against the predetermined threshold, ensuring restart conditions are only activated when appropriate. This closed-loop feedback control maintains reliability by verifying the engine is in a suitable state for restart while enabling rapid response when the threshold is met, thus resolving the contradiction between responsiveness and proper condition achievement.
Data Source
AI summary
A disclosed method of automatically stopping and restarting a vehicle engine determines if one or more stop/start enablement condition has been met. If the stop/start enablement condition or conditions have been met, the method initiates an engine shutdown. If a restart request is made before the engine reaches a predetermined threshold speed, then a first restart sequence is initiated. If a restart request is made when the engine speed is less than the predetermined threshold speed but still greater than 0, then a second restart sequence is initiated.