Spark Timing Control for Auto-Stop Engine Flare
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Solution Overview
Problem
Internal combustion engines experience engine flare during startup due to the combination of intake manifold pressure approaching barometric pressure and spark timing set to maximum braking torque, leading to overshooting of predetermined engine speed.
Innovation Solution
An engine control system that includes an actuator control module, a correction determination module, and a spark adjustment module to determine and adjust the spark timing based on the difference between target and measured engine speeds, minimizing overshoot and engine flare by smoothly increasing engine speed during startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spark timing is set to maximum braking torque during engine startup, then engine starting reliability is improved, but engine speed overshoot and engine flare occur
Solution Approach 1:
The patent dynamically adjusts the spark timing parameter during engine startup based on measured engine speed. Instead of using fixed maximum braking torque spark timing, the system modifies the spark timing angle in real-time to prevent engine speed overshoot while maintaining reliable engine starting. This parameter adjustment resolves the contradiction between starting reliability and speed control.
Solution Approach 2:
The patent implements a feedback control mechanism where the engine control module continuously monitors actual engine speed during startup and compares it to the target speed. Based on this feedback, the system adjusts the spark timing to minimize the difference between actual and target speeds, thereby preventing overshoot while maintaining starting reliability.
2Productivity
If intake manifold pressure approaches barometric pressure during startup, then air intake efficiency is improved, but engine flare and speed instability occur
Solution Approach 1:
The patent adjusts spark timing as a compensatory parameter in response to intake manifold pressure conditions. When intake pressure approaches barometric pressure, the system modifies spark timing to prevent engine flare, thereby maintaining speed stability while allowing efficient air intake.
3Loss of energy
If engine is shut down between startup and shutdown to increase fuel efficiency, then fuel consumption is reduced, but engine restart and speed control become more complex
Solution Approach 1:
The patent implements preliminary speed control measures during engine startup by adjusting spark timing before the engine reaches target speed. This preliminary action ensures smooth acceleration and prevents overshoot, making the subsequent engine shutdown and restart operations more predictable and easier to control, thereby managing the complexity of auto-stop/start functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively minimizes engine flare and overshoot during engine startup by adjusting spark timing, ensuring a smooth transition to the predetermined engine speed, thereby improving fuel efficiency and reducing vehicle acceleration/deceleration issues.
Implementation Method 1
The air/fuel mixture is combusted within one or more cylinders of the engine. Combustion of the air/fuel mixture may be initiated by, for example, injection of the fuel or spark provided by a spark plug.
Data Source
AI summary
An engine control system for an auto-stop/start vehicle, comprising: an actuator control module, a correction determination module, and a spark adjustment module. The actuator control module determines a target spark timing for a first time that is between a second time when engine cranking begins and a third time when a measured engine speed becomes greater than a predetermined engine speed after the second time. The correction determination module determines a spark timing correction for the first time based on a target engine speed and a measured engine speed. The spark adjustment module sets a spark timing for the first time based on the target spark timing and the spark timing correction.