Engine Stop Control via Intake Air Adjustment
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Solution Overview
Problem
The existing stop control systems for internal combustion engines fail to accurately stop the piston at a predetermined position due to variations in piston stop characteristics and aging, leading to inconsistent engine startability.
Innovation Solution
A stop control system that uses an intake air amount-adjusting valve, rotational speed-detecting means, and correlation determining means to set a target stop control start rotational speed based on actual stop characteristics, including aging, by controlling the intake air amount and determining correlations between stop control start and final compression stroke rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the opening degree of the intake air amount-adjusting valve is set based on a predetermined map according to rotational speed at compression top dead center, then the control system is simple and easy to implement, but the piston cannot be accurately stopped at the predetermined position due to variations in stop characteristic and aging
Solution Approach 1:
The patent implements feedback by detecting the actual stop position of the piston during engine stoppage and using this information to correct the target opening degree of the intake air amount-adjusting valve. The correction amount is calculated based on the difference between the actual stop position and the predetermined stop position, allowing the system to adapt to variations in piston stop characteristics and aging effects.
Solution Approach 2:
The patent changes the control parameter from a fixed predetermined map to a dynamic correction-based approach. The target opening degree is adjusted by adding a correction amount that varies with operating conditions, enabling the system to compensate for changes in piston stop characteristics over time while maintaining relatively simple control hardware.
2Reliability
If the intake air amount-adjusting valve is controlled to a predetermined opening degree during stoppage, then the control process is simple, but the piston stop characteristic varies with piston sliding friction and intake air amount, leading to inaccurate stopping
Solution Approach 1:
The system uses feedback from the actual piston stop position to adjust the control strategy. By detecting where the piston actually stops and comparing it with the target position, the system calculates a correction amount that is applied to the intake air amount-adjusting valve control, ensuring consistent and reliable piston positioning despite variations in friction and air amount.
Solution Approach 2:
The patent performs preliminary correction by calculating the correction amount based on detected operating parameters (rotational speed, intake air amount) before finalizing the valve control. This preliminary adjustment anticipates the variations in piston stop characteristics and pre-compensates for them, ensuring accurate stopping without complex real-time adjustments.
3Adaptability or versatility
If the stop control uses fixed parameters without correction, then the control system is simple and fast, but it cannot compensate for aging and product differences in piston stop characteristics
Solution Approach 1:
The feedback mechanism detects actual piston stop position and calculates correction amounts that account for aging and product variations. The correction is applied to the intake air amount-adjusting valve control, enabling the system to adapt to changing conditions without significant time delay, as the correction is calculated based on current operating parameters.
Solution Approach 2:
The system dynamically changes the control parameters by introducing correction amounts that vary with operating conditions such as rotational speed and intake air amount. This allows the system to adapt to aging and product differences while maintaining relatively fast response, as the corrections are applied continuously during the stop control process rather than requiring complete reconfiguration.
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
This system ensures accurate piston positioning, compensating for variations and aging, thereby improving engine startability and reducing vibrations and noise.
Implementation Method 1
the intake air amount-adjusting valve is controlled to a predetermined opening degree, whereby the magnitude of negative pressure within an intake passage is adjusted to stop the piston of the engine at a predetermined position
Implementation Method 2
A manner in which the piston stops during stoppage of the engine (hereinafter referred to as the 'stop characteristic of the piston') varies with the magnitude of the sliding friction of the piston
Data Source
AI summary
To provide a stop control system for an internal combustion engine, which is capable of accurately stopping a piston at a predetermined position while compensating for variation in the stop characteristic of the piston and aging thereof. The stop control system 1 for the engine 3 according the present invention controls a throttle valve 13a toward an open side when an engine speed NE becomes lower than a stop control start rotational speed NEIGOFTH after the engine 3 is stopped (step 42), whereby a final compression stroke rotational speed NEPRSFTGT is controlled to a predetermined reference value NENPFLMTO, to thereby control the stop position of the piston 3d to a predetermined position. Further, the correlation between the stop control start rotational speed NEIGOFTH and the final compression stroke rotational speed NEPRSFTGT is determined (step 5, FIG. 9), and based on the determined correlation, a target stop control start rotational speed NEICOFREFX is calculate and learned (step 11), for use in the stop control.