Engine Stop Control via Throttle Valve Timing
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Solution Overview
Problem
Existing stop control methods for internal combustion engines, particularly those with three-or-less cylinders, face challenges in consistently controlling the crank angle due to variable intake negative pressure effects, making it difficult to suppress vibration during engine start-up.
Innovation Solution
A stop control apparatus that determines the compression stroke before engine shutdown and controls the throttle valve to a predetermined opening degree while the intake valve is closed in all cylinders, reducing intake negative pressure and enhancing compression pressure to stabilize the crank angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the throttle opening degree is increased immediately before the engine stops, then the crank angle control is improved, but the braking effect due to intake negative pressure becomes unstable in three-or-less cylinder engines
Solution Approach 1:
The patent applies preliminary action by determining the compression stroke before engine stop in advance, and controlling the throttle valve opening degree specifically during the period when the intake valve is closed in all cylinders. This timing-based preliminary control ensures that the braking effect is applied at the most effective moment, stabilizing the crank angle even in three-or-less cylinder engines where intake negative pressure is not constant.
Solution Approach 2:
The patent changes the parameter of throttle valve opening degree dynamically based on engine operating conditions. By setting the throttle opening degree to a predetermined value specifically when the intake valve is closed in all cylinders during compression stroke, the system optimizes the braking effect to maintain stable crank angle control across different engine configurations.
2Stability of the object's composition
If the throttle valve is controlled to reduce intake negative pressure, then the crank angle stability is improved, but the load on throttle valve components increases
Solution Approach 1:
The patent applies partial action by controlling the throttle valve only during the specific period when the intake valve is closed in all cylinders, rather than continuously. This limited-time control reduces the cumulative load on throttle valve components while still achieving the necessary crank angle stability during the critical engine stop phase.
3Manufacturing precision
If the throttle opening degree is controlled based on intake air density, then the crank angle control is improved, but the complexity of the control system increases
Solution Approach 1:
The patent applies local quality by focusing control actions on a specific local condition - when the intake valve is closed in all cylinders during compression stroke. Instead of implementing complex continuous control based on multiple parameters like intake air density, the system applies a predetermined throttle opening degree only during this specific local timeframe, simplifying the control logic while maintaining effectiveness.
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 approach effectively controls the crank angle at shutdown, reducing vibration and extending the life of throttle valve components by minimizing unnecessary load, even in three-or-less cylinder engines where intake negative pressure is not constant.
Implementation Method 1
a piston in the intake stroke is braked due to intake negative pressure
Implementation Method 2
by increasing compression pressure in a compression stroke
Data Source
AI summary
A stop control apparatus (100) for an internal combustion engine performs stop control of a three-or-less cylinder internal combustion engine (200). The stop control apparatus for the internal combustion engine is provided with: a determining device (161) configured to determine a compression stroke immediately before the internal combustion engine stops; and a throttle valve controlling device (168) configured to control an opening degree of a throttle valve (208) to be a predetermined opening degree while an intake valve (211) is closed in all cylinders, in the compression stroke immediately before the internal combustion engine stops, which is determined by the determining device. This reduces an influence of an intake negative pressure in an intake stroke, and makes it possible to preferably control the crank angle when the engine stops, even in the three-or-less cylinder internal combustion engine.