Ignition Timing Control After Cutout for Cylinder Pressure Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ignition timing control systems in internal combustion engines fail to effectively manage cylinder pressure and fuel consumption/emissions when engine speed approaches a cut-out threshold, leading to potential damage and inefficiencies.
Innovation Solution
Implementing a control algorithm that adjusts ignition timing by reducing the ignition angle for the first sparks after a speed limitation operation, based on the number of sparks skipped, to manage cylinder pressure and prevent excessive fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the ignition angle is reduced to lower cylinder pressure after cutout, then cylinder pressure is controlled, but heat problems occur due to hot gases blowing into the muffler
Solution Approach 1:
The patent applies a preliminary ignition angle reduction before the cutout speed is reached. By reducing the ignition angle in advance (when engine speed is within a predetermined range below cutout speed), the system prepares the combustion characteristics to avoid excessive pressure buildup when sparks are resumed after cutout, while maintaining normal ignition timing to prevent heat issues in the muffler.
2Stress or pressure
If the ignition angle is reduced to prevent excessive cylinder pressure, then cylinder pressure is controlled, but fuel consumption and emissions increase
Solution Approach 1:
The patent applies local quality by implementing ignition angle reduction only in specific local conditions: when engine speed is within a predetermined range below the cutout speed threshold. This localized adjustment affects only specific combustion events rather than continuously reducing ignition angle, thereby controlling cylinder pressure during critical transitions while minimizing overall fuel consumption and emissions impact.
3Speed
If sparks are skipped to limit engine speed, then engine speed is controlled, but cylinder pressure increases excessively when sparks resume
Solution Approach 1:
The patent prepares for the resumption of sparks by reducing the ignition angle in advance, when engine speed is detected to be within a predetermined range below the cutout speed threshold. This preliminary ignition angle reduction ensures that when sparks resume after being skipped during cutout, the cylinder pressure does not increase excessively, thus protecting the engine while maintaining speed control.
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 reduces cylinder pressure, minimizes fuel consumption, and reduces emissions by allowing a controlled ignition angle adjustment post-speed limitation, enhancing engine longevity and performance.
Implementation Method 1
a spark plug disposed proximate to the combustion chamber to ignite the mixture by generating a spark such that ignition of the mixture drives a piston
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An internal combustion engine (1) may include a combustion chamber (41) into which a mixture (40) of fuel and air is supplied, a spark plug (50) disposed proximate to the combustion chamber (41) to ignite the mixture (40) by generating a spark such that ignition of the mixture drives a piston (6) operably coupled to a crank portion (12) of the engine (1), a speed sensor (102) configured to determine engine speed, and an electronic control unit (100) configured to control operation of the spark plug (50). The electronic control unit (100) may be configured to initiate a speed limitation operation in response to engine speed reaching a cut out speed threshold and to control ignition timing within an operating band (320) of ignition angles prior to engine speed reaching the cut out speed threshold. The speed limitation operation may include skipping application of sparks. The electronic control unit (100) is further configured to apply a changed ignition angle (330) relative to the operating band (320) for first at least one spark initiated after the speed limitation operation.