Decompression Valve Closure via Ignition Timing Adjustment
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Solution Overview
Problem
Existing decompression valves in internal combustion engines require tight tolerances to reliably close due to insufficient combustion pressure at late ignition points during idling, leading to complex production and potential engine kickback issues.
Innovation Solution
Advancing the ignition timing by approximately 5° crankshaft angle before the earliest ignition point for at least one engine cycle ensures a stronger combustion, resulting in higher combustion chamber pressure that reliably closes the decompression valve, eliminating the need for complex valve construction or precise manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the ignition timing is set to a late ignition point for smooth idling operation, then the engine runs smoothly with constant speed, but the combustion pressure becomes insufficient to reliably close the decompression valve
Solution Approach 1:
The control device performs a preliminary action by detecting the decompression valve opening state before combustion occurs, and based on this detection, adjusts the ignition timing to an advanced ignition point in advance of the combustion event. This preliminary detection and adjustment ensures that when combustion occurs, the decompression valve is reliably closed, while still allowing smooth idling operation at late ignition points during normal operation.
2Reliability
If tight tolerances are maintained on the decompression valve to ensure reliable closing, then the decompression valve closes reliably, but the production complexity and manufacturing cost increase
Solution Approach 1:
The invention replaces the mechanical solution of tight tolerances and complex valve construction with an electronic control system. The control device detects valve opening state and adjusts ignition timing electronically, substituting the need for mechanically precise decompression valve construction with a controllable ignition timing system that ensures reliable valve closing through timing adjustment rather than mechanical precision.
3Reliability
If the ignition timing is advanced to increase combustion pressure for reliable decompression valve closing, then the decompression valve closes reliably, but the engine may experience kickback
Solution Approach 1:
The control device uses feedback from the decompression valve opening state detection to determine the appropriate ignition timing. By detecting whether the decompression valve is open before combustion, the system provides feedback that allows it to select an advanced ignition timing only when necessary (when the valve is open), and use normal late ignition timing when the valve is closed, thus preventing kickback while ensuring reliable valve closing when needed.
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 method allows for reliable closure of the decompression valve without complex construction, preventing engine kickback and ensuring consistent idling speed, while maintaining smooth engine operation.
Implementation Method 1
the air-fuel mixture in the combustion chamber is ignited by a spark plug 23
Data Source
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AI summary
An internal combustion engine has one cylinder in which a piston is mounted to move back and forth, driving a crankshaft that is rotatably mounted in a crankcase. The piston defines a combustion chamber into which a spark plug protrudes. The internal combustion engine has a starting device for starting the engine. The spark plug ignites at an ignition point (ZZP) controlled by a timing device. Within an idle speed range, the ignition timing (ZZP) is controlled by an idle speed control unit, which has an earliest ignition point (ZZP1). The internal combustion engine has a decompression valve that, when open, connects the combustion chamber to a pressure relief chamber. This valve is open when the engine is started and closes when the pressure (p) in the combustion chamber exceeds a closing pressure (p1).To ensure the decompression valve closes safely, the ignition in the idle speed range is provided for at least one engine cycle (xl, x2) to deviate from the idle control at a closing ignition point (ZZP2) that is at least approximately 5° crankshaft angle before the earliest ignition point (ZZP1).