Micro-pilot Gas Engine Air-Fuel Control
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Solution Overview
Problem
Conventional micro-pilot injection ignition type gas engines face challenges in achieving stable combustion and precise air-fuel ratio control during starting, leading to engine speed fluctuations and prolonged idling times due to the lack of real-time feedback in skip-firing intermittent operations.
Innovation Solution
Incorporating a gas valve with adjustable throat area and opening/closing time, an engine speed detecting unit, cylinder pressure sensors, and a combustion diagnosis unit to monitor and adjust the skip-firing mode based on real-time engine conditions, ensuring the air-fuel ratio reaches a target value through intermittent opening/closing control of the gas valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If skip-firing intermittent operation is used to control air-fuel ratio during starting, then air-fuel ratio control capability is improved, but combustion stability deteriorates due to lack of real-time feedback
Solution Approach 1:
The patent implements a feedback control system where cylinder pressure sensors detect combustion pressure, the ECU processes this information to determine combustion status, and adjusts the gas valve opening/closing timing accordingly. This closed-loop feedback mechanism enables real-time adaptation of skip-firing patterns to maintain both precise air-fuel ratio control and stable combustion, resolving the contradiction between control precision and combustion reliability.
Solution Approach 2:
The patent dynamically adjusts the gas valve opening/closing timing and duration based on real-time engine conditions detected by sensors. The system transitions from fixed skip-firing patterns to adaptive, condition-based control, allowing the air-fuel ratio to be precisely controlled while maintaining combustion stability through continuous optimization of valve operation parameters.
2Device complexity
If conventional skip-firing operation is used without real-time monitoring, then device complexity is reduced, but starting time increases due to prolonged idling
Solution Approach 1:
The patent implements self-diagnosis and self-adjustment functionality where the ECU automatically monitors combustion pressure, determines combustion status, and adjusts valve timing without external intervention. This self-service capability enables the system to rapidly transition from starting to normal operation, reducing starting time while the added sensor and control logic represent acceptable complexity for achieving the time reduction goal.
Solution Approach 2:
The patent replaces conventional mechanical timing control with electronic control systems that use sensors to detect combustion conditions and electronically adjust valve timing. This substitution enables precise, real-time control that accelerates the starting process, reducing starting time despite the increased electronic complexity compared to purely mechanical systems.
3Measurement precision
If gas valve opening time is extended to improve air-fuel ratio control, then air-fuel ratio precision is improved, but engine speed fluctuations increase
Solution Approach 1:
The patent uses periodic opening/closing of the gas valve synchronized with engine rotation, where the valve opens for a precise duration during each cycle and closes during the remainder. This periodic action, controlled by the ECU based on crankshaft position and combustion status, enables precise air-fuel ratio control while maintaining engine speed stability through rhythmic, predictable fuel delivery patterns that prevent speed fluctuations.
Solution Approach 2:
The patent dynamically changes valve opening duration and timing parameters based on real-time detection of combustion pressure and engine conditions. By continuously adjusting these parameters to optimize air-fuel mixture formation while maintaining stable combustion, the system achieves precise air-fuel ratio control without causing engine speed fluctuations, resolving the contradiction between control precision and speed stability.
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 solution enhances the precision of air-fuel ratio control, stabilizes combustion, and reduces idling time by dynamically adjusting the skip-firing mode in response to engine conditions, resulting in smoother engine starting and reduced starting time.
Implementation Method 1
combustion of an amount of micro-pilot fuel-oil that is injected through a pilot fuel injector
Implementation Method 2
a cylinder pressure sensor provided at each cylinder so as to continually measure pressure levels as to each cylinder
Implementation Method 3
a gas valve that delivers and cuts fuel-gas at a position in front of each cylinder, so as to arbitrarily control a throat area as well as an opening/closing time span of the gas valve
Data Source
Figure 1
Figure 2
Figure 3-1~3-2
AI summary
What is disclosed is a micro-pilot injection ignition type gas engine, whereby an air fuel ratio control in starting the engine is executed with enhanced precision, by means of introducing skip-firing intermittent operations which reflect the engine operation conditions, while an idling time span can be shortened or omitted. The engine includes: a gas valve that opens and closes a fuel-gas passage in front of each cylinder, so as to arbitrarily control the throat area as well as the opening-closing time span of the gas valve; an engine speed detecting unit to detect the engine speed; a combustion diagnosis unit to detect an engine combustion state through a cylinder pressure distribution along elapsed time, as to each cylinder; an opening-closing control unit as to the gas valve, so as to control the intermittent opening-closing of the gas valve according to the levels of the detected engine speed as well as the cylinder pressure distribution; whereby, in starting the engine, the intermittent opening-closing of the gas-valve enables at least one skip-firing mode that brings an enhanced fuel-supply pressure-pulsation with which a relatively large amount of fuel-gas is supplied per engine cycle with firing so that the air fuel-gas ratio of each cylinder reaches a prescribed target value.