Engine Stop Timing Control via Throttle and Ignition Coordination
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Solution Overview
Problem
Internal combustion engines face challenges in stopping the piston at the target position without degrading emissions, as fuel residue in the intake pipe and cylinder can cause unintended combustion when air is introduced, leading to vibration issues and reduced engine startability.
Innovation Solution
A device and method utilizing a throttle valve controlled by an actuator and an electronic control unit to manage the intake air amount, revolving speed, and ignition timing, ensuring the piston stops at the correct position by opening the throttle valve before engine shutdown and stopping ignition to prevent combustion of residual fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the throttle valve is opened to introduce air to prevent the piston from stopping at the top dead center, then the piston stopping position is improved, but unintended combustion of residual fuel occurs leading to degraded emissions
Solution Approach 1:
The ignition is stopped in advance before the throttle valve is opened to prevent combustion of residual fuel. The ECU detects the throttle valve opening and preemptively cuts ignition signals, ensuring that when air is introduced, no combustion occurs. This preliminary action resolves the contradiction by preventing the harmful effect before it can occur.
Solution Approach 2:
The ECU uses feedback from the throttle opening sensor to control ignition timing. When the sensor detects that the throttle valve has opened, the ECU responds by stopping ignition. This closed-loop feedback mechanism ensures precise coordination between throttle opening and ignition cessation, preventing emissions while maintaining proper piston stopping position.
2Stability of the object's composition
If the throttle valve is completely closed to reduce vibration during engine stopping, then vibration is reduced, but the piston stops near the top dead center degrading engine startability
Solution Approach 1:
The throttle valve transitions from a static completely closed position to a dynamic opening state. The ECU controls the throttle actuator to open the valve at the appropriate timing, creating a dynamic system that adapts to the engine stopping phase. This dynamic adjustment allows the system to balance vibration reduction with proper piston stopping position for improved startability.
Solution Approach 2:
The system uses feedback from the revolving speed sensor and throttle opening sensor to dynamically adjust throttle valve position. Based on engine speed and throttle position feedback, the ECU determines the optimal throttle opening timing to prevent piston stopping at top dead center while minimizing vibration, thereby improving engine startability.
3Manufacturing precision
If the throttle valve is opened before ignition is stopped to control piston position, then the piston stopping position is improved, but combustion of residual fuel occurs increasing emissions
Solution Approach 1:
The ignition is stopped in advance before the throttle valve is opened to prevent combustion of residual fuel. The ECU detects the throttle valve opening and preemptively cuts ignition signals, ensuring that when air is introduced, no combustion occurs. This preliminary action resolves the contradiction by preventing the harmful effect before it can occur.
Solution Approach 2:
The system applies preliminary anti-action by stopping ignition before opening the throttle valve. This preemptive measure counteracts the potential harmful effect of fuel combustion by removing the ignition source in advance, allowing the throttle to open safely without causing emissions problems.
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
Effectively prevents the piston from stopping at the top dead center, reducing vibration and maintaining engine startability while minimizing emissions by precisely controlling the throttle valve and ignition timing.
Implementation Method 1
even if combustion is stopped in a combustion chamber, a piston performs reciprocal motion tens of times until inertia of the piston is consumed by friction
Implementation Method 2
fuel adhered to the intake pipe and cylinder makes combustion as air is introduced
Implementation Method 3
a revolving speed sensor that detects a revolving speed of the internal combustion engine
Data Source
AI summary
A control device for stopping an engine, configured in such a manner that, when, after the ignition of the engine is turned off, the throttle valve is opened to introduce air in order to avoid that a piston stops near the top dead center, the control device stops the engine without causing a misalignment of the stop position of the piston and without degrading emission quality. A device for controlling the timing at which ignition is stopped when an internal combustion engine becomes stopped is provided with: a means for sending, depending on the rotational speed (NE) of the internal combustion engine detected by a rotational speed sensor decreasing to a level lower than or equal to a predetermined value (Np) after the ignition (55) is turned off and the throttle valve (14) is closed, a signal to an actuator (18) so that the throttle valve (14) is opened in order to control the stop position of a piston; and also provided with a means for stopping the ignition of the ignition plug when the throttle valve (14) becomes opened in order to control the stop position of the piston.