Marine dual-fuel engine diesel oil / natural gas switching mode optimization method

Abstract

According to the method for optimizing the dual-fuel diesel oil / natural gas dual-fuel switching mode of the marine engine, the injection quality and injection timing of ignition diesel oil are controlled through a diesel oil ECU, the injection quality and injection timing of natural gas fuel are controlled through a natural gas ECU, the heat efficiency and combustion stability of the engine are improved, and the displacement of THC and CO in the dual-fuel mode is reduced. The marine engine diesel oil / natural gas dual-fuel switching mode optimization method is suitable for the technical field of dual-fuel engine control, and the problems that when an engine is switched between a pure diesel oil mode and a dual-fuel mode, the rotating speed fluctuation is large, operation is unstable, and emission is deteriorated can be solved. After the marine engine diesel oil / natural gas dual-fuel switching mode optimization method is practically applied, the dynamic property, economical efficiency, emission performance and safety of the dual-fuel engine are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of marine dual-fuel engine control, and more specifically to a method for optimizing a diesel / natural gas switching mode of a marine dual-fuel engine. Background Art

[0002] As the emission regulations of the International Maritime Organization become increasingly stringent, diesel / natural gas dual-fuel engines with clean emissions are gradually being used in the marine field.

[0003] Marine dual-fuel engines use diesel as the pilot fuel and combustible natural gas as the main fuel. In the actual operation of marine dual-fuel engines, when switching between pure diesel mode and dual-fuel mode, it is easy to cause large fluctuations in engine speed, unstable operation, and deterioration of emissions, which affect the performance of the engine. The switching of dual-fuel engines can achieve two switching modes: switching from diesel mode to natural gas mode and switching from natural gas mode to diesel mode. The process is extremely complicated.

[0004] According to the operating requirements of the dual-fuel engine under actual working conditions, the switching of different modes can be completed quickly and smoothly. The present invention proposes an optimization method for the diesel / natural gas switching mode of a marine dual-fuel engine, which reduces the occurrence of large speed fluctuations, unstable operation and deteriorated emissions of the dual-fuel engine during the switching process, and provides a theoretical basis for the efficient operation of the marine dual-fuel engine. Summary of the invention

[0005] The method for optimizing the diesel / natural gas dual-fuel switching mode for a marine engine of the present invention is applicable to the field of control technology of dual-fuel engines, and can solve the problems of large speed fluctuation, unstable operation, and deteriorated emissions when the engine switches between pure diesel mode and dual-fuel mode. After the method for optimizing the diesel / natural gas dual-fuel switching mode for a marine engine of the present invention is put into practical use, the power, economy, emissions, and safety of the dual-fuel engine will be greatly improved.

[0006] The present invention proposes a method for optimizing the diesel / dual-fuel switching mode of a marine engine, the steps of which include: the dual-fuel engine is in an idle state at the beginning, that is, the default fuel mode-pure diesel mode, at which time the engine working injection device only injects diesel to complete the work. According to the engine speed and load conditions, if the conditions meet the requirements for switching to the dual-fuel mode, the engine begins to prepare for the dual-fuel mode switching. In the dual-fuel mode state, the diesel ECU controls the injection amount and injection timing of the diesel, and the natural gas ECU controls the injection amount and injection timing of the natural gas fuel. Determine whether the natural gas fuel is sufficient. Only when the fuel is sufficient can the engine finally switch to the dual-fuel mode and operate stably under the working condition. When the engine fails, in order to ensure working safety, the natural gas ECU actively cuts off the natural gas supply and switches the operating mode to the pure diesel mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A diagram of a diesel and natural gas dual fuel switching mode optimization method for a marine engine; Implementation

[0008] The present invention will be further described below in conjunction with the accompanying drawings.

[0009] like Figure 1 As shown, the present invention proposes a method for optimizing the diesel / dual fuel switching mode of a marine engine, the steps of which include: the dual fuel engine is in an idle state at the beginning, that is, the default fuel mode-pure diesel mode, at which time the engine working injection device only injects diesel to complete the work. According to the engine speed and load conditions, if the conditions meet the requirements for switching to the dual fuel mode, the engine starts to prepare for the dual fuel mode switching. In the dual fuel mode state, the diesel ECU controls the injection amount and injection timing of the diesel, and the natural gas ECU controls the injection amount and injection timing of the natural gas fuel. Determine whether the natural gas fuel is sufficient. Only when the fuel is sufficient can the engine finally switch to the dual fuel mode and operate stably under the working condition. When the engine fails, in order to ensure working safety, the natural gas ECU actively cuts off the natural gas supply and switches the operating mode to the pure diesel mode.

[0010] A further preferred embodiment of the present invention is: The engine speed and load determined in step 2 are the criteria for switching the dual-fuel engine between the pure diesel mode and the dual-fuel mode.

[0011] The step 3 realizes the injection stability and precision control of the pilot diesel, which plays an important role in improving the combustion and emission of the dual-fuel engine. The combustion process of the dual-fuel engine is improved by optimizing the diesel injection amount and injection timing.

[0012] The step 4 can effectively solve the problems of misfire and knock in dual-fuel engines by achieving fast and accurate control of the air-fuel ratio for the intake system. It takes a certain amount of time for natural gas to mix with air and enter the cylinder, and the control of the natural gas ECU will also lag, causing the engine speed to fluctuate greatly.

[0013] In step 6, the engine quickly switches to the dual fuel mode when the engine fails, such as when the load suddenly increases or decreases or when a problem occurs in the natural gas injection device.

[0014] A method for optimizing a diesel / natural gas dual fuel switching mode for a marine engine according to the present invention is as follows: Figure 1 As shown, the dual fuel is in the default combustion mode - pure diesel mode at idle speed. When the engine speed reaches a certain condition, the engine fuel mode switches from pure diesel mode to dual fuel mode. The diesel ECU controls the injection amount and injection timing of the fuel, and the natural gas ECU controls the injection amount and injection timing of the gas. If the fuel is sufficient, the engine switches from pure diesel mode to dual fuel mode, and controls the injection step of natural gas according to the engine load. When the engine encounters a fault, the natural gas ECU actively cuts off the supply of natural gas, and the engine switches to pure diesel mode.

Claims

1. A method for optimizing diesel / natural gas dual fuel switching mode for a marine engine, characterized in that: The steps include: (1) The dual-fuel engine is in idle state at the beginning, that is, the default fuel mode - pure diesel mode. At this time, the engine working injection device only injects diesel to complete the work; (2) Based on the engine speed and load, if the conditions meet the requirements for switching to the dual-fuel mode, the engine begins to prepare for the dual-fuel mode switch; (3) When changing the fuel, it is necessary to control the diesel fuel. In the dual-fuel mode, the diesel is used as the pilot fuel to control the injection amount and injection timing of the diesel; (4) When the dual-fuel engine is running, the injection amount and injection timing of natural gas are controlled according to the engine operating conditions; (5) Determine whether the natural gas fuel is sufficient. Only when the fuel is sufficient can the engine finally switch to dual-fuel mode and operate stably under the working conditions; (6) When an engine failure occurs, in order to ensure working safety, the control system actively cuts off the natural gas supply and switches the operating mode to pure diesel mode.

2. The method for optimizing the diesel / natural gas switching mode according to claim 2, characterized in that: In step (2), when the engine speed reaches the requirement of dual-fuel mode operation, the diesel ECU starts to send the current gas injection amount to the gas injection control system, and the natural gas ECU starts to calculate the gas injection mass and injection timing.

3. The method for optimizing the diesel / natural gas switching mode according to claim 3, characterized in that: In step (3), in the dual-fuel mode, the engine uses the diesel ECU to set the diesel injection amount and injection timing, which can not only burn and produce work but also ignite the natural gas.

4. The method for optimizing the diesel / natural gas switching mode according to claim 4, characterized in that: In step (4), under medium and high loads, the dual-fuel engine can achieve combustion of diesel and natural gas in a suitable ratio to produce work. The natural gas ECU controls the injection amount and injection timing of natural gas, which has a great influence on the power and emission of the engine.

5. The method for optimizing the diesel / natural gas switching mode according to claim 5, characterized in that: In step (5), the dual-fuel engine freely switches between the pure diesel mode, the dual-fuel mode and the maximum gas mode, so that the engine can have good power, economy and emission. The dual-fuel engine mostly uses the pure diesel mode when running at low load, and switches to the pure diesel mode when the natural gas reserves are insufficient.

6. The diesel / natural gas switching mode optimization method according to claim 6, characterized in that: In step (6), when the gas injection mechanism of the engine fails or the boost pressure exceeds the limit, the natural gas ECU will actively cut off the natural gas supply and switch the operating mode to the pure diesel mode to ensure working safety.

Images