Dual-Fuel Engine Air-Fuel Ratio Control via Bypass Valves
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Dual fuel engines face challenges in achieving optimal air-fuel ratio control and responsiveness in gas mode, particularly in terms of air flow amount control, due to differences in air-fuel ratio requirements between diesel and gas modes, leading to inefficiencies and suboptimal performance.
Innovation Solution
The engine device optimizes the supercharger by controlling the opening degrees of the exhaust bypass valve and air supply bypass valve in accordance with engine load variations, ensuring an optimized air-fuel ratio and improving trackability and responsiveness during load changes, even when operating in gas mode with a supercharger optimized for diesel mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the supercharger is optimized for diesel mode, then diesel mode performance is improved, but gas mode air-fuel ratio control deteriorates
Solution Approach 1:
The patent implements dynamic control of bypass valves to adjust the effective supercharger capacity in real-time based on operating mode. The first bypass valve (bypassing compressor inlet) and second bypass valve (bypassing turbine outlet) are controlled to dynamically modify air flow through the supercharger, enabling the same supercharger to provide appropriate air flow characteristics for both diesel and gas modes without requiring separate optimization for each mode.
2Quantity of substance
If the supercharger capacity is increased for diesel mode, then air flow amount for diesel mode is improved, but air flow control responsiveness in gas mode deteriorates
Solution Approach 1:
The patent segments the air flow control by introducing bypass valves that can independently regulate air flow through different paths. The first bypass valve segments the compressor inlet flow, while the second bypass valve segments the turbine outlet flow. This segmentation allows the large-capacity supercharger to be effectively down-sized or modulated for gas mode operation, improving responsiveness without sacrificing the high air flow capability needed for diesel mode.
3Adaptability or versatility
If bypass valves are added to control air flow, then air-fuel ratio control is improved, but device complexity increases
Solution Approach 1:
The bypass valves serve multiple functions: they control air flow quantity for air-fuel ratio management, they modulate supercharger effective capacity, and they enable transition between different operating modes. By making these valves multi-functional, the patent reduces the need for separate control mechanisms for each function, thereby limiting the increase in overall system complexity while achieving comprehensive air-fuel ratio control capability.
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 configuration minimizes air deficiency during combustion, allowing the engine to operate optimally in gas mode with improved air-fuel ratio control and responsiveness, expanding the control range of air pressure and ensuring adequate air supply, even under varying load conditions.
Implementation Method 1
a supercharger 49, and an intercooler 51
Implementation Method 2
control of each of the opening degree of the exhaust bypass valve and the opening degree of the air supply bypass valve
Implementation Method 3
a supercharger 49, and an intercooler 51
Data Source
Figure 1
Figure 2
Figure 3
AI summary
When a load on an engine is higher than a predetermined load L3, an engine device 21 brings the opening degree of a main throttle valve V1 to a fully-open opening degree. Further, the engine device 21 performs feedback control on an air supply bypass valve V2 and performs map control on an exhaust bypass valve V3 referring to data table DT2 to allow pressure inside an intake manifold 67 to be adjusted to a target value appropriated to the load.