CN108331658B - Gas supply system and method for improving frequency response of natural gas engine based on precombustion chamber enrichment - Google Patents

Gas supply system and method for improving frequency response of natural gas engine based on precombustion chamber enrichment Download PDF

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CN108331658B
CN108331658B CN201810112431.5A CN201810112431A CN108331658B CN 108331658 B CN108331658 B CN 108331658B CN 201810112431 A CN201810112431 A CN 201810112431A CN 108331658 B CN108331658 B CN 108331658B
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combustion chamber
air
engine
independent
gas
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CN108331658A (en
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程勇
杨雪
王玉宝
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Shandong University
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Shandong University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B19/00—Engines characterised by precombustion chambers
    • F02B19/12—Engines characterised by precombustion chambers with positive ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0027—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures the fuel being gaseous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0203—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels characterised by the type of gaseous fuel
    • F02M21/0215—Mixtures of gaseous fuels; Natural gas; Biogas; Mine gas; Landfill gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/04—Engine intake system parameters
    • F02D2200/0404—Throttle position
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
    • F02D2200/101—Engine speed
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

The invention discloses a gas supply system and a method for improving the frequency response of a natural gas engine based on pre-combustion chamber enrichment, and the gas supply system comprises a pre-combustion chamber, a main combustion chamber, a pre-combustion chamber independent gas inlet injection device and a system controller, wherein the pre-combustion chamber is communicated with the main combustion chamber through a lower connecting channel, a spark plug and an installation channel of the independent gas inlet injection device are arranged above the pre-combustion chamber, the independent gas inlet injection device arranges a nozzle in the pre-combustion chamber through the installation channel, and the system controller enables the pre-combustion chamber independent gas inlet injection device to inject gas into the pre-combustion chamber independently through controlling the opening and closing of the pre-combustion chamber independent gas inlet injection device so as to enrich the concentration of mixed gas in the pre-combustion chamber and change the.

Description

Gas supply system and method for improving frequency response of natural gas engine based on precombustion chamber enrichment
Technical Field
The invention relates to the field of natural gas engine frequency response improvement, in particular to a gas supply system and a method for improving the frequency response of a pre-combustion chamber type large-cylinder-diameter natural gas engine based on a pre-combustion chamber independent gas inlet device.
Background
The shortage of petroleum resources and the problem of ecological environment pollution become two major obstacles restricting the forward development of the internal combustion engine industry at the present stage, the search for efficient and clean alternative energy and the successful application of the alternative energy to engineering machinery and vehicle engineering become technical problems to be urgently researched and solved by countries in the world. Among the many alternative energy sources, natural gas is widely concerned due to its high calorific value, clean combustion emissions, and abundant world reserves. The large-bore natural gas engine for ships and engineering machinery has the advantages that the cylinder diameter of the combustion chamber is large, flame propagation distance in the combustion chamber is long, and flame propagation speed is low during combustion of natural gas, so that knocking can easily occur at the far end in the combustion chamber. However, the flame propagation speed of the lean mixture is low, the combustion speed is slow, and the large-cylinder-diameter natural gas engine is easy to generate flame quenching or cyclic fire when the in-cylinder tissues are subjected to lean combustion, so that the engine has large cyclic fluctuation, poor working stability and high unburned HC and CO emission. The high-energy ignition system can improve the ignition reliability of the lean mixture and accelerate the combustion speed in the cylinder, thereby being beneficial to realizing the stable lean combustion in the combustion chamber. The excess air coefficient of the mixed gas is an index for researching the components of the combustible mixed gas, is the ratio of the air mass actually provided by burning unit mass fuel to the theoretically required air mass, and can be used for representing the concentration of the mixed gas, wherein the mixed gas is a lean mixed gas when the excess air coefficient of the mixed gas is more than 1, and the mixed gas is a rich mixed gas when the excess air coefficient of the mixed gas is less than 1. For a large-bore natural gas engine, a high-energy ignition energy can be obtained by adopting the pre-combustion chamber ignition system, and further stable lean combustion is realized in the main combustion chamber. The volume of a general precombustion chamber is 1% -3% of the volume of a main combustion chamber, the precombustion chamber is utilized to independently intake air to organize thicker mixed air in the precombustion chamber, the main combustion chamber organizes thin mixed air, the common spark plug is utilized to ignite the mixed air in the precombustion chamber, the pressure and the temperature in the precombustion chamber are rapidly increased, and then the pressure difference is formed between the precombustion chamber and the main combustion chamber, under the action of the pressure difference, high-energy substances generated by combustion in the precombustion chamber enter the main combustion chamber through a connecting channel between the precombustion chamber and the main combustion chamber, distributed multi-point ignition is formed in the thin mixed air in the main combustion chamber, the main combustion chamber is reliably ignited, the flame propagation distance in the main combustion chamber is shortened, the main combustion chamber is.
Aiming at a pre-combustion chamber type large-bore natural gas engine, a mechanical mixer or an air inlet multi-point injection mode is mostly adopted to realize the premixing of natural gas and air, a throttle valve is utilized to control the mixed gas volume entering a main combustion chamber, and the mixed gas volume entering an air cylinder through a main air inlet is different under different throttle valve opening degrees. When the engine is loaded suddenly, the amount of air mixture entering the cylinder cannot be increased in time, so that the power output of the engine cannot meet the load requirement, and the running stability of the engine is reduced. Ideally, when the load is suddenly applied, in order to meet the load demand, the throttle opening should be increased, the air input should be increased in time, and in order to meet the demand of larger power output, the engine should be smoothly transited to the larger load, and the concentration of the mixture entering the combustion chamber should be properly enriched at the same time, so as to increase the output power of the engine. However, when the load is suddenly applied in actual use, the air intake amount is difficult to follow in time after the opening degree of the throttle valve is increased, and the change of the concentration of the mixed gas is difficult to accurately control for the engine adopting the air intake premixing mode of the mechanical mixer. For the natural gas engine matched with the exhaust gas turbocharger, the energy source for supercharging the intake air by the supercharger is the exhaust of the previous working cycle, when the load is suddenly added, the exhaust energy of the engine is insufficient, so that the supercharging capacity of the supercharger is low, at the moment, the supercharger can not effectively supercharge the intake air of the engine and can bring resistance to the intake air, the intake air amount can not meet the requirement, and the running stability of the engine is poor.
In summary, the conventional natural gas engine with a precombustion chamber is organized in a main combustion chamber to meet the requirements of thermal efficiency and emission, but when a sudden load change working condition occurs, the engine speed obviously fluctuates due to the fact that the air input and the air input concentration of the main combustion chamber cannot respond to the load requirement in time, and the running stability of the engine is low.
Disclosure of Invention
In order to solve the defects of the prior art, the invention provides an air supply system and an air supply method for improving the frequency response of a natural gas engine based on pre-combustion chamber enrichment, which can organize lean combustion in a main combustion chamber under a stable working condition, reduce the thermal load of the engine, improve the thermal efficiency of the engine and reduce the emission; under the transient working condition of sudden load addition, the combustion speed of the mixed gas in the main combustion chamber is improved by thickening the concentration of the mixed gas in the main combustion chamber, the energy released after the mixed gas is combusted is increased, the power output of the engine is further increased rapidly, the fluctuation of the rotating speed of the engine is reduced, and the running stability of the engine is improved.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the utility model provides an air feed system based on natural gas engine frequency response is improved in precombustion chamber enrichment, includes precombustion chamber, main combustion chamber, the independent injection apparatus and the system control ware that admits air of precombustion chamber, the precombustion chamber communicates with each other with main combustion chamber through the sub-unit connection passageway, the precombustion chamber top is equipped with spark plug and independent injection apparatus installation passageway that admits air, independent injection apparatus that admits air sets up the nozzle in the precombustion chamber through the installation passageway, the system control ware is through opening and closing of the independent injection apparatus that admits air of control precombustion chamber, makes it independently admit air with the enrichment precombustion chamber in the gas mixture concentration to change main combustion chamber in the gas mixture concentration.
Further, the gas pressure and the excess air coefficient injected by the pre-combustion chamber independent air inlet injection device are calibrated according to the service condition of the engine, and the gas pressure and the excess air coefficient of the pre-combustion chamber independent air inlet are constant values for a fixed engine.
Furthermore, the air excess coefficient of the independent air intake of the precombustion chamber is matched with the air excess coefficient of the mixed air in the main combustion chamber, so that the combustion speed of the mixed air formed in the precombustion chamber is high, and the air pressure of the independent air intake of the precombustion chamber ensures that the enriched air enters the precombustion chamber and then sweeps away the residual waste gas in the previous cycle in the precombustion chamber as much as possible.
Further, the system controller judges the running state of the engine by acquiring signals of a rotating speed sensor and signals of a throttle position sensor, the system controller monitors the pressure in a main air inlet channel of the engine in real time through a pressure sensor, and the system controller monitors the excess air coefficient of the mixed gas participating in-cylinder combustion in real time.
Further, the system controller determines the opening time and the injection pulse width of the independent pre-chamber air intake injection device according to the judgment on the running state of the engine and by combining the pressure in the main air inlet passage, the gas pressure of independent pre-chamber air intake, the mixed gas participating in-cylinder combustion and the excess air coefficient of independent pre-chamber air intake.
Further, the system controller controls the independent pre-combustion chamber air inlet injection device to be opened for a certain pulse width at a set crank angle according to detection signals of the rotating speed sensor and the crank shaft or cam shaft phase sensor.
A method of improving natural gas engine frequency response based on prechamber enrichment, comprising:
the method comprises the steps that the gas pressure and the gas excess air coefficient injected by an independent pre-combustion chamber air inlet injection device are calibrated according to the service condition of an engine, and the gas pressure and the gas excess air coefficient of independent pre-combustion chamber air inlet are constant values for a fixed engine;
detecting the throttle opening, the real-time rotating speed, the pressure in a main air inlet and the excess air coefficient of the mixed gas participating in-cylinder combustion of the engine;
determining the opening time and the injection pulse width of the independent pre-combustion chamber air intake injection device according to a MAP graph of the real-time rotating speed, the target rotating speed, the opening degree of a throttle valve, the gas pressure of independent pre-combustion chamber air intake, the excess air coefficient of mixed gas participating in-cylinder combustion and the pressure in a main air inlet passage;
detecting the rotating speed of the engine and the phase position of a crankshaft or a camshaft, and judging the rotating angle value of the crankshaft in the actual operation of the engine;
and driving the independent air inlet injection device of the pre-combustion chamber to open a certain pulse width under the preset crank angle value.
Furthermore, the opening time and the injection pulse width of the independent pre-combustion chamber air inlet injection device are required to enable the air entering the pre-combustion chamber to sweep out the residual waste gas in the previous cycle in the pre-combustion chamber as much as possible, and the concentration of the mixed air in the pre-combustion chamber is enriched while the residual waste gas is swept out.
Furthermore, when the opening time and the injection pulse width of the independent pre-combustion chamber air inlet injection device enrich the concentration of the mixed gas in the pre-combustion chamber, the concentration of the mixed gas in the pre-combustion chamber is distributed, reliable ignition is guaranteed, and the flame propagation speed of the mixed gas under the concentration is ensured to be high, so that the quick combustion of the mixed gas in the pre-combustion chamber is realized.
Furthermore, the opening time and the injection pulse width of the independent air intake injection device of the precombustion chamber can effectively enrich the lean mixed gas in the main combustion chamber through the enriched gas quantity entering the main combustion chamber through the connecting channel under the pressure difference action of the precombustion chamber and the main combustion chamber when the engine is in the transition working condition of sudden load, and the injection quantity and the injection time of the enriched gas are simultaneously enriched in the concentration of the mixed gas in the precombustion chamber, so that the natural gas quantity in the main combustion chamber is increased, the combustion speed in the main combustion chamber is increased, and the energy released after the mixed gas in the main combustion chamber is combusted is increased.
In the running process of the pre-combustion chamber type natural gas engine, the system controller monitors the working running state of the engine in real time, judges the real-time rotating speed and load condition of the engine, adjusts the independent air intake injection strategy of the pre-combustion chamber in time, reduces the rotating speed fluctuation and ensures the stable running of the engine.
Compared with the prior art, the invention has the beneficial effects that:
1) the ignition reliability and the combustion speed of the lean mixture in the main combustion chamber are improved based on the enrichment of the precombustion chamber, stable lean combustion can be organized in the precombustion chamber type large-cylinder-diameter natural gas engine, the thermal efficiency of the engine is improved, and the emission is reduced;
2) when the precombustion chamber type large-bore natural gas engine is in a transient working condition of sudden loading, the precombustion chamber is used for thickening the lean mixed gas in the main combustion chamber, so that the natural gas volume in the main combustion chamber is increased, the combustion speed in the main combustion chamber is accelerated, the energy released after the mixed gas in the main combustion chamber is combusted is improved, the power output of the engine is further increased rapidly, the rotating speed fluctuation caused by the sudden loading is reduced, and the working stability of the engine is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
FIG. 1 is a gas supply system for improving the frequency response of a natural gas engine based on prechamber enrichment according to the present invention;
wherein, 1, spark plug; 2. a pre-chamber independent intake air injection device; 3. a precombustion chamber; 4. a connecting channel; 5. a main combustion chamber; 6. a system controller; 7. a rotational speed sensor; 8. a crankshaft or camshaft phase sensor; 9. a throttle position sensor; 10. a primary inlet pressure sensor; 11. an excess air ratio sensor.
Detailed Description
The invention is further described with reference to the following detailed description of embodiments and drawings.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
In the present invention, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only terms of relationships determined for convenience of describing structural relationships of the parts or elements of the present invention, and are not intended to refer to any parts or elements of the present invention, and are not to be construed as limiting the present invention.
In the present invention, terms such as "fixedly connected", "connected", and the like are to be understood in a broad sense, and mean either a fixed connection or an integrally connected or detachable connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be determined according to specific situations by persons skilled in the relevant scientific or technical field, and are not to be construed as limiting the present invention.
As described in the background art, in the prior art, the natural gas engine with the prechamber is organized in a lean combustion mode in a main combustion chamber to meet the requirements of thermal efficiency and emission, but when a sudden load change condition occurs, the engine speed fluctuates obviously due to the fact that the air inflow and the air inflow concentration of the main combustion chamber cannot respond to the load requirement in time, and therefore the running stability of the engine is low. In order to solve the technical problems, the application provides a control system and a method for improving the frequency response of a natural gas engine based on pre-combustion chamber enrichment aiming at the natural gas engine with a large cylinder diameter, which can organize lean combustion in a main combustion chamber under a stable working condition, reduce the thermal load of the engine, improve the thermal efficiency of the engine and reduce the emission; under the transient working condition of sudden load addition, the combustion speed in the main combustion chamber is accelerated by thickening the concentration of the mixed gas in the main combustion chamber, the energy released after the mixed gas is combusted is increased, the power output of the engine is further increased rapidly, the rotating speed fluctuation of the engine is reduced, and the running stability of the engine is improved.
A gas supply system for improving natural gas engine frequency response based on precombustion chamber enrichment specifically comprises the following components:
as shown in figure 1, the gas supply system for improving the frequency response of the natural gas engine based on the enrichment of the precombustion chamber mainly comprises a precombustion chamber 3, a main combustion chamber 5, a precombustion chamber independent air inlet injection device 2 and a system controller 6, the precombustion chamber 3 is communicated with a main combustion chamber 5 through a lower connecting passage 4, an installation passage of a spark plug 1 and an independent air inlet injection device 2 is arranged above the precombustion chamber 3, the independent air inlet injection device 2 arranges a nozzle in the precombustion chamber 3 through the installation passage, scavenging and enriching the prechamber 3, inserting the spark plug 1 into the prechamber 3 with a spark plug gap, and igniting the mixed gas in the precombustion chamber 3 at the ignition moment, wherein the system controller 6 controls the opening and closing of the precombustion chamber independent air inlet injection device 2 to inject the precombustion chamber independent air inlet into the precombustion chamber 3 so as to enrich the concentration of the mixed gas in the precombustion chamber and change the concentration of the mixed gas in the main combustion chamber.
The lean mixture formed after premixing natural gas and air enters the main combustion chamber 5 through the air inlet channel in the air inlet process, the independent air inlet injection device 2 injects pure gas or the rich mixture of natural gas and air into the precombustion chamber 3, the residual waste gas in the previous cycle in the precombustion chamber 3 is swept away, and the concentration of the mixture in the precombustion chamber 3 is enriched. In the compression stroke, the lean mixture in the main combustion chamber 5 gets into the precombustion chamber 3 through the connecting channel 4 between precombustion chamber 3 and the main combustion chamber 5, and mix with the dense mixture in the precombustion chamber 3, make the interior mixture concentration distribution of precombustion chamber guarantee reliable ignition, and ensure that the flame propagation speed of mixture is very fast under this concentration, the energy of releasing after the mixture burns in the precombustion chamber 3 gets into main combustion chamber 5 through connecting channel 4, ignite the lean mixture in the main combustion chamber 5, realize the stable lean combustion in the main combustion chamber 5.
In specific implementation, the gas pressure and the excess air coefficient injected by the precombustion chamber independent air inlet injection device 2 are calibrated according to the service condition of the engine, and for a fixed engine, the gas pressure and the excess air coefficient of the precombustion chamber independent air inlet are constant values. In the running process of the engine, the system controller 6 determines the real-time running state of the engine by acquiring a rotating speed sensor signal 7 and a throttle position sensor signal 9, the system controller 6 acquires the air inlet pressure in a main air inlet channel of the engine by using a pressure sensor 10, and the system controller 6 acquires the excess air coefficient of the mixed air participating in-cylinder combustion by using an excess air coefficient sensor 11. The system controller 6 determines the opening time and the injection pulse width of the independent pre-combustion chamber air intake injection device 2 according to the MAP graph of the real-time engine speed, the target engine speed, the throttle opening, the gas pressure of independent pre-combustion chamber air intake, the excess air coefficient of mixed gas participating in-cylinder combustion and the pressure in the main air intake passage, and then judges the crank angle value in the actual operation of the engine through signals of the speed sensor 7 and signals of the crank shaft or cam shaft phase sensor 8 to drive the independent pre-combustion chamber air intake injection device 2 to open a certain pulse width under the preset crank angle.
The system controller 6 adjusts the time when the independent air enters the precombustion chamber 3 by adjusting the opening time of the precombustion chamber independent air inlet injection device 2, and further adjusts the amount of gas and the entering time when the independent air enters the precombustion chamber 3 and enters the main combustion chamber 5 through the connecting passage 4 under the pressure difference action of the precombustion chamber 3 and the main combustion chamber 5. The system controller 6 adjusts the air inflow of independent air intake by adjusting the opening pulse width of the independent air intake injection device 2 of the precombustion chamber, adjusts the total amount of gas entering the precombustion chamber 3, further adjusts the total amount of gas entering the main combustion chamber 5 through the connecting channel 4, and changes the enrichment degree of lean mixture gas in the main combustion chamber 5.
The invention provides a method for improving the frequency response of a natural gas engine based on pre-combustion chamber enrichment on the basis of gas supply system hardware, a system controller 6 monitors the running state of the engine in real time, the injection strategy of the independent pre-combustion chamber air inlet injection device is adjusted in time by adjusting and controlling the double-scale of the opening time and the injection pulse width of the independent pre-combustion chamber air inlet injection device 2, so that the accurate control of the pure gas quantity or the rich mixture quantity of natural gas and air entering the pre-combustion chamber 3 and the entering time is realized, when the engine is in a sudden load transition working condition, the injection amount and injection timing of the enriched gas are such that while the mixture concentration in the enrichment pre-chamber 3 is being enriched, the enrichment gas quantity entering the main combustion chamber 5 through the connecting channel 4 under the action of the pressure difference between the precombustion chamber 3 and the main combustion chamber 5 can be ensured to effectively enrich the dilute mixed gas in the main combustion chamber 5, on one hand, the concentration of the mixed gas in the main combustion chamber 5 is increased, so that the combustion speed is accelerated; on the other hand, after the natural gas amount in the main combustion chamber 5 is increased, the energy released by the mixed gas in the main combustion chamber 5 after combustion is improved. In conclusion, the method can rapidly improve the output power of the engine to respond to the load demand under the transient working condition of sudden load, the response speed of the air supply system is high, the enriched gas directly enters the combustion chamber without being influenced by the intake charge coefficient, and the enrichment effect of the mixed gas in the main combustion chamber 5 is obvious, so that the rotating speed of the engine does not obviously fluctuate under the transient working condition of sudden load, the fluctuation rate of the instantaneous rotating speed is low, and the engine rapidly and stably transits to the large-load working condition.
A method of improving natural gas engine frequency response based on prechamber enrichment, comprising:
the method comprises the steps that the gas pressure and the gas excess air coefficient injected by an independent pre-combustion chamber air inlet injection device are calibrated according to the service condition of an engine, and the gas pressure and the gas excess air coefficient of independent pre-combustion chamber air inlet are constant values for a fixed engine;
detecting the throttle opening, the real-time rotating speed, the pressure in a main air inlet and the excess air coefficient of the mixed gas participating in-cylinder combustion of the engine;
determining the opening time and the injection pulse width of the independent air intake of the precombustion chamber according to a MAP graph of the real-time rotating speed, the target rotating speed, the opening degree of a throttle valve, the air pressure of the independent air intake of the precombustion chamber, the excess air coefficient of a mixed gas participating in-cylinder combustion and the pressure in a main air intake passage;
detecting the rotating speed of the engine and the phase position of a crankshaft or a camshaft, and judging the rotating angle value of the crankshaft in the working operation of the engine;
and driving the independent air inlet injection device of the pre-combustion chamber to open a certain pulse width under the preset crank angle value.
The opening time and the injection pulse width of the precombustion chamber independent air inlet injection device 2 are such that the gas entering the precombustion chamber 3 sweeps the residual waste gas in the previous cycle in the precombustion chamber 3 as much as possible, and the concentration of the mixed gas in the precombustion chamber 3 is enriched while the residual waste gas is swept.
When the opening time and the injection pulse width of the independent pre-combustion chamber air inlet injection device 2 are used for enriching the concentration of the mixed gas in the pre-combustion chamber 3, the concentration distribution of the mixed gas in the pre-combustion chamber 3 is ensured to be reliably ignited, and the flame propagation speed of the mixed gas under the concentration is ensured to be higher, so that the mixed gas in the pre-combustion chamber 3 is quickly combusted.
The opening time and the injection pulse width of the independent air intake injection device 2 in the precombustion chamber are used for ensuring that the amount of the enriched gas entering the main combustion chamber 5 through the connecting channel 4 can effectively enrich the lean mixed gas in the main combustion chamber 5 under the pressure difference action of the precombustion chamber 3 and the main combustion chamber 5 when the engine is in the transient working condition of sudden loading, and increasing the natural gas amount in the main combustion chamber 5, thereby improving the combustion speed in the main combustion chamber 5 and increasing the energy released after the mixed gas in the main combustion chamber 5 is combusted.
In the specific implementation, when the engine is loaded suddenly from a small load to a large load, the system controller 6 judges the real-time running state of the engine through the real-time rotating speed sensor 7 signal and the throttle position sensor 9 signal, and then determines the opening time and the injection pulse width of the independent pre-combustion chamber air intake injection device 2 according to the MAP graph of the real-time rotating speed of the engine, the target rotating speed, the throttle opening, the air pressure of independent pre-combustion chamber air intake, the excess air coefficient of mixture involved in-cylinder combustion and the pressure in the main air intake passage. After the independent air intake injection device 2 of precombustion chamber is opened, the independent air intake of precombustion chamber gets into in the precombustion chamber 3, sweep the interior residual waste gas of precombustion chamber 3, make partial precombustion chamber independently admit air and carry the interior residual waste gas of precombustion chamber 3 to get into main combustion chamber 5 through connecting channel 4, the enrichment gas that gets into the precombustion chamber 3 is under the pressure differential effect of precombustion chamber 3 and main combustion chamber 5 afterwards, part is retained in precombustion chamber 3, make the interior gas mixture concentration distribution of precombustion chamber 3 satisfy the fast combustion requirement when igniteing, part gets into main combustion chamber 5 through connecting channel, the thin gas mixture in the enrichment main combustion chamber 5. The enriched gas directly enters the combustion chamber without being influenced by the air intake charge coefficient, and the enrichment effect on the lean mixed gas in the main combustion chamber 5 is obvious, so that the output power of the engine is rapidly increased under the sudden load working condition, the instantaneous rotating speed fluctuation rate is low, and the engine is rapidly and stably transited to the large load working condition.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.

Claims (9)

1. The utility model provides a gas supply system based on precombustion room enrichment improves natural gas engine frequency response which characterized in that: the system controller enables the independent air intake injection device of the precombustion chamber to inject air into the precombustion chamber independently to enrich the concentration of mixed air in the precombustion chamber and change the concentration of the mixed air in the main combustion chamber by controlling the opening and closing of the independent air intake injection device of the precombustion chamber;
and the system controller determines the opening time and the injection pulse width of the independent pre-combustion chamber air intake injection device according to the judgment of the running state of the engine and by combining the pressure in the main air inlet passage, the gas pressure of independent pre-combustion chamber air intake, the mixed gas participating in-cylinder combustion and the excess air coefficient of independent pre-combustion chamber air intake.
2. An air supply system for improving the frequency response of a natural gas engine based on pre-combustion chamber enrichment as claimed in claim 1, characterized in that the pressure and the excess air coefficient of the gas injected by the pre-combustion chamber independent air injection device are calibrated according to the service condition of the engine, and the pressure and the excess air coefficient of the gas of the pre-combustion chamber independent air injection are fixed values for a fixed engine.
3. The gas supply system as claimed in claim 2, wherein the air excess factor of the independent prechamber charge is matched to the air excess factor of the mixture in the main combustion chamber to ensure that the mixture in the prechamber burns faster, and the air pressure of the independent prechamber charge ensures that the enriched gas is forced into the prechamber to scavenge as much residual exhaust gas from the previous cycle in the prechamber as possible.
4. An air supply system for improving the frequency response of a natural gas engine based on pre-chamber enrichment as claimed in claim 1, wherein the system controller judges the running state of the engine by collecting a signal of a speed sensor and a signal of a throttle position sensor, the system controller monitors the pressure in the main air inlet channel of the engine in real time through a pressure sensor, and the system controller monitors the excess air coefficient of the mixture participating in-cylinder combustion in real time.
5. An air supply system for improving the frequency response of a natural gas engine based on pre-chamber enrichment as claimed in claim 1, wherein the system controller controls the pre-chamber independent air injection device to open a certain pulse width at a set crank angle according to the detection signals of the speed sensor and the crank or camshaft phase sensor.
6. A method of improving natural gas engine frequency response based on prechamber enrichment, comprising:
the method comprises the steps that the gas pressure and the gas excess air coefficient injected by an independent pre-combustion chamber air inlet injection device are calibrated according to the service condition of an engine, and the gas pressure and the gas excess air coefficient of independent pre-combustion chamber air inlet are constant values for a fixed engine;
detecting the throttle opening, the real-time rotating speed, the pressure in a main air inlet and the excess air coefficient of the mixed gas participating in-cylinder combustion of the engine;
determining the opening time and the injection pulse width of the independent air intake of the precombustion chamber according to a MAP graph of the set rotating speed, the target rotating speed, the opening degree of a throttle valve, the air pressure of the independent air intake of the precombustion chamber, the excess air coefficient of a mixed gas participating in-cylinder combustion and the pressure in a main air intake passage;
detecting the rotating speed of the engine and the phase position of a crankshaft or a camshaft, and judging the rotating angle value of the crankshaft in the actual operation of the engine;
determining the opening time and the injection pulse width of the independent pre-combustion chamber air intake injection device according to the judgment of the running state of the engine and by combining the pressure in the main air inlet passage, the gas pressure of independent pre-combustion chamber air intake, the mixed gas participating in-cylinder combustion and the excess air coefficient of independent pre-combustion chamber air intake;
and driving the independent air inlet injection device of the pre-combustion chamber to open a certain pulse width under the preset crank angle value.
7. The method of improving natural gas engine frequency response based on prechamber enrichment as set forth in claim 6, characterized in that the opening timing and injection pulsewidth of the prechamber independent intake injection means are such that the gas entering the prechamber sweeps as much residual exhaust gas from the previous cycle in the prechamber as possible and enriches the mixture concentration in the prechamber while sweeping the residual exhaust gas.
8. The method for improving natural gas engine frequency response based on pre-chamber enrichment as claimed in claim 6, wherein the opening time and the injection pulse width of the independent pre-chamber air injection device are such that when the concentration of the mixture in the pre-chamber is enriched, the concentration distribution of the mixture in the pre-chamber ensures reliable ignition and the flame propagation speed of the mixture at the concentration is ensured to be high so as to realize rapid combustion of the mixture in the pre-chamber.
9. The method as claimed in claim 6, wherein the opening time and the injection pulse width of the independent pre-combustion chamber air injection device ensure that the amount of the enrichment gas entering the main combustion chamber through the connecting channel under the pressure difference between the pre-combustion chamber and the main combustion chamber can effectively enrich the lean mixture in the main combustion chamber and increase the natural gas amount in the main combustion chamber, thereby increasing the combustion speed in the main combustion chamber and increasing the energy released by the mixture in the main combustion chamber after combustion.
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CN111456858B (en) * 2020-02-18 2022-03-18 哈尔滨工程大学 Natural gas engine fuel gas injection method based on' previous cycle effect
CN112177764A (en) * 2020-10-06 2021-01-05 山东交通学院 Shock wave multistage reflection strong premixing precombustion chamber structure
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