CN115596561A

CN115596561A - Injection control method and combustion system of diesel ignition high-pressure liquid ammonia direct injection internal combustion engine

Info

Publication number: CN115596561A
Application number: CN202211260660.4A
Authority: CN
Inventors: 林浩; 卢文健; 欧阳晓春; 都成君; 黄世宏; 严波; 汪祥本; 曹翰卿; 殷勇; 李智
Original assignee: Dongfeng Commercial Vehicle Co Ltd
Current assignee: Dongfeng Commercial Vehicle Co Ltd
Priority date: 2022-10-14
Filing date: 2022-10-14
Publication date: 2023-01-13

Abstract

The application relates to a diesel ignition high-pressure liquid ammonia direct injection internal combustion engine injection control method and a combustion system, belonging to the technical field of internal combustion engines, wherein the diesel ignition high-pressure liquid ammonia direct injection internal combustion engine combustion control method comprises the following steps: when the internal combustion engine is started or is in a small load working condition, the internal combustion engine runs in a pure diesel mode; when the internal combustion engine meets the liquid ammonia injection condition and the piston moves to the position near a compression top dead center, controlling a diesel ammonia nozzle to be opened, and injecting diesel oil and liquid ammonia with preset amount into a main combustion chamber for compression and combustion; after the diesel oil is compression-ignited, the liquid ammonia is subjected to thermal flash in the main combustion chamber and is ignited by flame of the diesel oil combustion to form stable diffusion combustion. The ammonia fuel has higher octane number than diesel oil, so the ammonia fuel has better anti-knock explosion capability than diesel oil, and can allow an internal combustion engine to set a higher compression ratio, thereby improving the power density and the thermal efficiency of the internal combustion engine.

Description

Injection control method and combustion system of diesel ignition high-pressure liquid ammonia direct injection internal combustion engine

Technical Field

The application relates to the technical field of internal combustion engines, in particular to a diesel ignition high-pressure direct injection liquid ammonia internal combustion engine injection control method and a combustion system.

Background

The internal combustion engine is a power machine, it is through making the fuel burn in the machine inside, and the thermal engine that it emits heat energy direct conversion power, the internal combustion engine in the broad sense not merely includes reciprocating piston internal combustion engine, rotary piston engine and free piston engine, also include the jet engine of the rotary impeller type, but the internal combustion engine generally known as piston internal combustion engine, the piston internal combustion engine is the most common in the past and reciprocating piston type, the piston internal combustion engine mixes fuel and air, burn in its cylinder, the heat energy released makes the cylinder produce the high-temperature high-pressure fuel gas, the fuel gas expands and pushes the piston to do work, and then export the mechanical work through the crank link mechanism or other mechanisms, drive the driven machinery to work, there are diesel engine and petrol engine commonly, through converting the internal energy into the mechanical energy, do work through changing the internal energy.

CN 11269689A discloses a marine liquid ammonia fuel supply and fuel recycling system, which comprises an ammonia fuel engine, a liquid ammonia supply system, a liquid ammonia recycling system and a liquid ammonia nitrogen purging and ventilating system. The liquid ammonia low-pressure pump is used for pressurizing the liquid ammonia to 18bar and transporting the liquid ammonia to the liquid ammonia buffer tank. 1 or more liquid ammonia low-pressure pumps can be configured in each storage cabin according to requirements; the liquid ammonia high-pressure pump further pressurizes liquid ammonia to 70bar, and the liquid ammonia high-pressure pump can be configured with 1 or more than one according to requirements. The liquid ammonia heater realizes the temperature adjustment of the liquid ammonia fuel and meets the requirement of the temperature range of 45 +/-10 ℃. Therefore, the ammonia fuel engine can use liquid ammonia fuel with the pressure of 70bar and the temperature of 45 +/-10 ℃ to realize the power propulsion of the ship.

CN113202660A discloses a fuel supply system of a single ammonia fuel marine diesel engine, wherein an ammonia storage tank, a gasification tank, and a filter chamber are sequentially connected, the outlet of the filter chamber is respectively connected with an ammonia pipeline and a hydrogen pipeline, the ammonia pipeline is provided with an ammonia pressurization tank and an ammonia high-pressure common rail pipe at the last time, the ammonia high-pressure common rail pipe is connected with an engine through an ammonia electronic injection valve, the hydrogen pipeline is provided with an ammonia decomposition furnace, a hydrogen pressurization tank, an intermediate hydrogen storage tank, and a hydrogen high-pressure common rail pipe in sequence, the intermediate hydrogen storage tank is connected with the hydrogen high-pressure common rail pipe through an electromagnetic flow valve, and the hydrogen high-pressure common rail pipe is connected with the engine through a hydrogen electronic injection valve.

CN114427494A discloses a dual-fuel engine system, comprising: the dual-fuel engine is provided with a main combustion chamber, a pre-combustion chamber, a first direct injection device and a second direct injection device, wherein the first direct injection device is communicated with the main combustion chamber, and the second direct injection device is communicated with the pre-combustion chamber; the main combustion chamber is communicated with the precombustion chamber through a communicating hole; the liquid ammonia storage device is communicated with the first direct injection device, and liquid ammonia fuel stored in the liquid ammonia storage device is injected into the main combustion chamber to form premixed gas; a high cetane number fuel storage device communicated with the second direct injection device and used for injecting the high cetane number fuel stored in the high cetane number fuel storage device into the pre-combustion chamber; the high cetane fuel in the pre-combustion chamber enters the main combustion chamber in a jet mode to form jet flame so as to ignite the premixed gas in the main combustion chamber.

However, when the ammonia-fueled combustion device is used, the ammonia fuel has strong combustion inertia, single fuel cannot ensure stable combustion, and hydrogen is adopted for ignition, but the maturity of a hydrogen-fueled vehicle-mounted system or an ammonia cracking hydrogen production vehicle-mounted system is lower than that of a diesel-fueled vehicle-mounted system, so that the hydrogen-fueled vehicle-mounted system or the ammonia cracking hydrogen production vehicle-mounted system is difficult to put into practical application.

Disclosure of Invention

The embodiment of the application provides a diesel ignition high-pressure direct injection liquid ammonia internal combustion engine injection control method and a combustion system, and aims to solve the problems that in the related technology, an internal combustion engine is high in carbon emission, ammonia fuel is difficult to combust, reaction is insufficient, and the compression ratio of a combustion chamber is difficult to improve.

The first aspect of the embodiments of the present application provides a method for controlling injection of a diesel-ignited high-pressure direct-injection liquid ammonia internal combustion engine, including:

when the internal combustion engine is started or is in a small load working condition, the internal combustion engine runs in a pure diesel mode;

when the internal combustion engine meets the liquid ammonia injection condition and the piston moves to the position near a compression top dead center, controlling a diesel ammonia nozzle to be opened, and injecting diesel oil and liquid ammonia with preset amount into a main combustion chamber for compression and combustion;

after the diesel oil is compression-ignited, the liquid ammonia is subjected to thermal flash in the main combustion chamber and is ignited by flame of the diesel oil combustion to form stable diffusion combustion.

In some embodiments, the internal combustion engine satisfies the conditions of liquid ammonia injection, i.e., engine speed, throttle opening, intake air temperature, coolant temperature, and ammonia level.

In some embodiments, the diesel injector injects diesel when the piston moves 0 ° to 8 ° before compression top dead center.

In some embodiments, the diesel injector injects liquid ammonia when the piston moves 4 ° before compression top dead center to 20 ° after top dead center.

In some embodiments, the diesel fuel has a gross calorific value of 1% to 10%.

In some embodiments, the diesel fuel has a gross calorific value of 2% to 5%.

In some embodiments, the liquid ammonia injection pressure is not less than 600bar.

The embodiment of the present application provides in a second aspect a diesel ignition high-pressure direct injection liquid ammonia internal combustion engine combustion system, including:

the diesel system comprises a diesel tank, the outlet end of the diesel tank is connected with a diesel pump through a pipeline, and the diesel pump is connected with a diesel ammonia nozzle positioned in an internal combustion engine cylinder through a diesel rail;

the ammonia system comprises a liquid ammonia tank, the outlet end of the liquid ammonia tank is connected with a liquid ammonia booster pump through a pipeline, and the liquid ammonia booster pump is connected with a diesel ammonia nozzle positioned in an internal combustion engine cylinder through a liquid ammonia rail;

the diesel-ammonia nozzle and the liquid ammonia booster pump are connected with the electronic control unit, and the electronic control unit is used for controlling the internal combustion engine to start or operate in a pure diesel mode under a small-load working condition;

In some embodiments, all be provided with the pressure sensor who is connected with electronic control unit on the diesel rail and the liquid ammonia rail, be provided with the liquid ammonia stop valve on the connecting pipeline between liquid ammonia tank and the liquid ammonia booster pump.

In some embodiments, the diesel rail and the liquid ammonia rail are respectively provided with a pressure sensor connected with the electronic control unit, and a liquid ammonia stop valve is arranged on a connecting pipeline between the liquid ammonia tank and the liquid ammonia booster pump.

In some embodiments, the plurality of liquid ammonia spray holes are circumferentially distributed on the outer side of the diesel spray hole, the diameter of each liquid ammonia spray hole is larger than 1.5mm, and the included angle between each liquid ammonia spray hole and the central axis of the diesel spray nozzle is 70-75 degrees.

The beneficial effect that technical scheme that this application provided brought includes:

(1) The embodiment of the application provides a diesel ignition high-pressure direct injection liquid ammonia internal combustion engine injection control method and a combustion system, and an electronic control unit is adopted to control an ammonia system to be matched with a diesel system, so that a main combustion chamber of an internal combustion engine cylinder is fed, and a diffusion combustion mode of diesel ignition ammonia fuel is realized, so that the problems of difficulty in combustion of the ammonia fuel and insufficient reaction are solved.

(2) Because the ammonia fuel is adopted, the octane number of the ammonia fuel is higher than that of diesel oil, so that the anti-knock explosion capability of the ammonia fuel is better than that of the diesel oil, the internal combustion engine can be allowed to set a higher compression ratio, and the power density and the heat efficiency of the internal combustion engine are further improved.

(3) Due to the fact that the high-pressure injection diffusion combustion mode of injecting diesel oil and liquid ammonia near the compression top dead center is adopted, compared with the existing low-pressure injection premixing combustion mode, the high-pressure injection diffusion combustion mode can achieve higher diesel oil substitution rate, further broadens carbon reduction potential of the internal combustion engine, and compared with the low-pressure injection premixing combustion mode, the high-pressure injection diffusion combustion mode can remarkably reduce emission of NH, NOx and greenhouse gases discharged by the engine.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an embodiment of the present application;

fig. 2 is a schematic structural diagram of an internal combustion engine according to an embodiment of the present application.

In the drawings, the reference numbers indicate the following list of parts:

1. a cylinder cover; 2. a diesel ammonia nozzle; 3. a main combustion chamber; 4. a cylinder liner; 5. a piston; 6. a connecting rod; 7. a liquid ammonia tank; 8. an internal combustion engine; 10. a diesel pump; 11. an electronic control unit; 12. a diesel tank; 13. a liquid ammonia stop valve; 14. a liquid ammonia booster pump; 15. liquid ammonia rail; 16. a diesel rail.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The embodiment of the application provides a diesel ignition high-pressure direct injection liquid ammonia internal combustion engine injection control method and a combustion system, and can solve the problems that in the related technology, the internal combustion engine is high in carbon emission, ammonia fuel is difficult to combust, reaction is insufficient, and the compression ratio of a combustion chamber is difficult to improve.

Referring to fig. 1 to 2, a first aspect of the embodiment of the present application provides an injection control method for a diesel-pilot high-pressure direct-injection liquid ammonia internal combustion engine, including:

when the internal combustion engine 8 is started or is in a small load working condition, the internal combustion engine 8 runs in a pure diesel mode;

when the internal combustion engine 8 meets the liquid ammonia injection condition and the piston 5 moves to the position near a compression top dead center, controlling the diesel ammonia nozzle 2 to be opened, and injecting diesel oil and liquid ammonia with preset amount into the main combustion chamber 3 for compression and combustion;

after compression ignition of diesel oil, liquid ammonia is heated and flashed in the main combustion chamber 3 and is ignited by flame generated by combustion of the diesel oil to form stable diffusion combustion.

The injection control method of the diesel ignition high-pressure direct injection liquid ammonia internal combustion engine comprises the steps that when the internal combustion engine 8 is started or is in a small-load working condition, the internal combustion engine 8 runs in a pure diesel mode;

the low-load condition refers to one of the operating conditions of the internal combustion engine 8, and the operating condition of the internal combustion engine 8 can be roughly divided into three stages: the method comprises the steps of small load, medium and small load and large load, wherein the three stages of division can be determined by collecting working condition parameters of the diesel internal combustion engine, the small load refers to the accelerator opening degree within the full rotating speed range of 0-30%, the medium and small load refers to the accelerator opening degree within the full rotating speed range of 30-60%, and the large load refers to the accelerator opening degree within the full rotating speed range of 60-100%.

When the internal combustion engine 8 meets the liquid ammonia injection condition and the piston 5 moves to the vicinity of a compression top dead center, the diesel ammonia nozzle 2 is controlled to be opened, and diesel oil and liquid ammonia with preset amount are injected into the main combustion chamber 3 for compression and combustion;

When the piston 5 in the cylinder of the internal combustion engine 8 moves to be close to a compression top dead center, diesel oil and liquid ammonia can be sequentially or simultaneously injected into the main combustion chamber 3 of the internal combustion engine 8 through the diesel oil and ammonia nozzles 2, the purpose of injecting the diesel oil is to ignite the liquid ammonia through flames of diesel oil combustion, and further the problems of difficult combustion and insufficient reaction of ammonia fuel are solved, it is required to be stated that preferably, after the moment of injecting the liquid ammonia by the diesel oil and ammonia nozzles 2 is a preset interval time after the diesel oil is injected, the liquid ammonia injected by the diesel oil and ammonia nozzles 2 is injected into the flames of diesel oil combustion, the liquid ammonia is ignited by the flames of diesel oil combustion, then the liquid ammonia is continuously injected and continuously combusted in the main combustion chamber until the combustion stroke in the main combustion chamber 3 of the internal combustion engine 8 is finished, when the next piston 5 moves to be close to the compression top dead center, the diesel oil and ammonia are repeatedly ignited through the flames of diesel oil combustion and a stable diffusion combustion mode is formed;

it should be noted that, because the ignition point of the diesel is lower than that of the liquid ammonia, the liquid ammonia is injected into the diesel at the same time or in advance of the diesel, and the diesel is ignited first, the flame of the diesel ignites the liquid ammonia, and the ability of the ammonia fuel to resist shock explosion is better than that of the diesel, so that the internal combustion engine can be allowed to set a higher compression ratio, the power density and the thermal efficiency of the internal combustion engine are further improved, and meanwhile, compared with the existing mode of low-pressure injection premixed combustion in an intake stroke, the high-pressure injection diffusion combustion mode can inject more ammonia fuel for combustion, and can realize a higher diesel substitution rate;

it should be noted that the maximum ammonia-doping specific energy of the low-pressure injection premixed combustion mode is about 80%, and the high-pressure injection diffusion combustion mode of the present application can achieve 97% diesel substitution rate, further widening the carbon reduction potential of the internal combustion engine; compared with a pure diesel mode, the high-pressure injection diffusion combustion mode has similar indicated thermal efficiency, cooling and exhaust loss, and can obviously reduce the emission of greenhouse gases CO2 and N2O, and compared with a low-pressure injection premixing combustion mode, the high-pressure injection diffusion combustion mode can obviously reduce the emission of NH3, NOx and greenhouse gases emitted by an engine;

it should be noted that, diesel oil compression ignition type ignition forms a plurality of flame central points, improves ignition energy, realizes lean burn operation with a relative air-fuel ratio (AFR) of 2 and above, reduces the temperature of a combustion chamber, effectively inhibits the generation of harmful emissions Nox, and can reduce the emissions Nox by an ammonia gas post-treatment technology, thereby realizing near zero emission, so that the whole combustion chamber has an ultra-clean and effective combustion effect, almost or not at all generates pollutants such as nitrogen oxides, and the carbon emission is reduced by 95% compared with a diesel engine.

In some alternative embodiments: referring to fig. 1 to 2, the present application provides an injection control method for a diesel-ignited high-pressure direct-injection liquid ammonia internal combustion engine, where an internal combustion engine 8 of the injection control method for the diesel-ignited high-pressure direct-injection liquid ammonia internal combustion engine satisfies liquid ammonia injection conditions of an internal combustion engine rotation speed, an accelerator opening, an intake air temperature, a coolant temperature, and an ammonia liquid level.

The internal combustion engine 8 of the injection control method for the diesel ignition high-pressure direct injection liquid ammonia internal combustion engine according to the embodiment of the application meets the condition that liquid ammonia injection is performed on the rotating speed, the opening degree of an accelerator, the intake air temperature, the temperature of a cooling liquid and the liquid level of ammonia of the internal combustion engine, and specifically, when the internal combustion engine 8 runs under medium and small loads, the electronic control unit 11 controls the opening degree of an electronic control waste gas valve by reading parameters of an intake air temperature sensor, changes the intake amount of waste gas, further adjusts the intake air temperature to the optimal evaporation temperature of the liquid ammonia, and improves the heat efficiency.

In some alternative embodiments: referring to fig. 1 to 2, the present embodiment provides an injection control method for a diesel-pilot high-pressure liquid ammonia direct injection internal combustion engine, in which a diesel injector 2 injects diesel when a piston 5 moves 0 ° to 8 ° before compression top dead center.

According to the diesel ignition high-pressure direct injection liquid ammonia internal combustion engine injection control method, the diesel injection nozzle 2 injects diesel when the piston 5 moves to 0-8 degrees before the compression top dead center, and the diesel injection timing is the injection timing of the diesel, so that the injected diesel can be guaranteed to be stably compressed.

In some alternative embodiments: referring to fig. 1 to 2, the present embodiment provides an injection control method for a diesel-pilot high-pressure direct-injection liquid ammonia internal combustion engine, in which a diesel injector 2 injects liquid ammonia when a piston 5 moves to 4 ° before compression top dead center to 20 ° after top dead center.

According to the diesel ignition high-pressure liquid ammonia direct injection internal combustion engine injection control method, the diesel ammonia nozzle 2 injects liquid ammonia when the piston 5 moves to 4 degrees before compression top dead center and 20 degrees after the compression top dead center, the piston 5 moves to 4 degrees before the compression top dead center and 20 degrees after the compression top dead center, which means the injection timing range of the liquid ammonia, the liquid ammonia injection pulse width can be adjusted according to the demand of liquid ammonia injection amount, the liquid ammonia is injected after the diesel is ignited, the liquid ammonia injection closing timing is controlled before 20 degrees of the top dead center, the liquid ammonia is prevented from being injected to the cylinder wall of the internal combustion engine 8 and permeating between the piston and the cylinder wall, so that the engine oil is diluted, the condition that the cylinder pulling failure occurs to the piston and the like is caused, the injected liquid ammonia can be ignited by the flame of the diesel combustion after being atomized, and the liquid ammonia injection closing timing is controlled before 4 degrees before the top dead center, in the diesel combustion process, the liquid ammonia is injected to the flame of the diesel combustion, which is favorable for the heat absorption atomization of the liquid ammonia, and then ignited by the flame of the diesel combustion.

In some alternative embodiments: referring to fig. 1 to 2, the embodiment of the application provides an injection control method for a diesel-ignited high-pressure direct-injection liquid ammonia internal combustion engine, and the total heating value of diesel of the injection control method for the diesel-ignited high-pressure direct-injection liquid ammonia internal combustion engine is 1% to 10%.

The total heat value of the diesel oil of the injection control method of the diesel ignition high-pressure direct injection liquid ammonia internal combustion engine of the embodiment of the application is 1% -10%, and the total heat value refers to the total heat required to be generated by combustion calibrated by a combustion engine 8 (the heat value ratio refers to the formula of the lower graph)

In the above formula:

d%: the gross calorific value of the diesel oil accounts for the ratio;

mass of liquid ammonia;

LHV _NH3 : low heating value of liquid ammonia;

the quality of the diesel oil;

LHV _D : low heating value of diesel oil.

The total heat generated by the combustion of the diesel oil and the liquid ammonia is used in the method, when the percentage of the heat generated by the combustion of the injected diesel oil to the total heat value is less than 1%, the heat and flame generated by the combustion of the corresponding injected diesel oil cannot support the atomization of the liquid ammonia and can be ignited, and when the percentage of the heat generated by the combustion of the diesel oil injected into the diesel oil to the total heat value is more than 10%, the carbon-containing waste gas generated by the combustion of the corresponding injected diesel oil is more, the substitution rate of liquid ammonia fuel is low, and the carbon emission cannot be effectively reduced.

In some alternative embodiments: referring to fig. 1 to 2, an embodiment of the present application provides an injection control method for a diesel-ignited high-pressure liquid ammonia direct injection internal combustion engine, where a total heating value of diesel is 2% to 5%.

The total heat value ratio of the diesel of the injection control method of the diesel ignition high-pressure direct injection liquid ammonia internal combustion engine is preferably 2% -5%, the total heat value refers to the total heat quantity required to be generated by combustion calibrated by the internal combustion engine 8, the total heat quantity generated by combustion of the diesel and the liquid ammonia is the sum of the heat quantity generated by combustion of the diesel and the liquid ammonia, and when the percentage of the combustion heat quantity of the injected diesel and the total heat value is between 2% -5%, the heat quantity and flame generated by combustion of the corresponding injected diesel can fully ensure that the liquid ammonia is atomized and ignited to form continuous diffusion combustion.

In some alternative embodiments: referring to fig. 1 to 2, the present embodiment provides an injection control method for a diesel-pilot high-pressure liquid ammonia direct injection internal combustion engine, where the injection pressure of liquid ammonia is not lower than 600bar.

According to the injection control method of the diesel ignition high-pressure direct injection liquid ammonia internal combustion engine, the injection pressure of liquid ammonia is not lower than 600bar, and the liquid ammonia is guaranteed to be injected into a cylinder of the internal combustion engine 8 and can be continuously injected with required fuel quantity and diffused and combusted after being ignited by flame of diesel combustion.

It should be noted that 600bar is not necessarily the optimum pressure, since the diesel injection pressure is rising all the time, this pressure is worth setting to ensure that the injection is capable of achieving diffusion combustion, and if the injection pressure is too low near top dead center, the needle valve cannot be opened, and in addition, a high injection pressure can ensure that the required amount of fuel is injected near top dead center.

Referring to fig. 1 to 2, a second aspect of the embodiment of the present application provides a combustion system of a diesel-piloted high-pressure direct-injection liquid ammonia internal combustion engine, including:

the diesel system comprises a diesel tank 12, the outlet end of the diesel tank 12 is connected with a diesel pump 10 through a pipeline, and the diesel pump 10 is connected with a diesel ammonia nozzle 2 positioned in a cylinder of the internal combustion engine through a diesel rail 16;

the ammonia system comprises a liquid ammonia tank 7, the outlet end of the liquid ammonia tank 7 is connected with a liquid ammonia booster pump 14 through a pipeline, and the liquid ammonia booster pump 14 is connected with a diesel ammonia nozzle 2 positioned in a cylinder of the internal combustion engine 8 through a liquid ammonia rail 15;

the electronic control unit 11, the diesel-ammonia nozzle 2 and the liquid ammonia booster pump 14 are all connected with the electronic control unit 11, and the electronic control unit 11 is used for controlling the internal combustion engine 8 to start or operate in a pure diesel mode under a small-load working condition;

after the diesel oil is subjected to compression ignition, the liquid ammonia is heated and flashed in the main combustion chamber 3 and is ignited by flame of the diesel oil combustion to form stable diffusion combustion.

According to the combustion system of the diesel ignition high-pressure direct-injection liquid ammonia internal combustion engine, the electronic control unit 11 controls the diesel system and the ammonia system to operate respectively, the internal combustion engine 8 adopts a pure diesel mode when being started, the electronic control unit 11 can make judgment according to the running state of the engine after being started, the pure diesel mode is still adopted when the load is small, when the rotating speed of the engine, the opening degree of an accelerator, the temperature of a cooling liquid and the ammonia liquid level meet liquid ammonia injection conditions, the electronic control unit 11 is switched to a diesel/liquid ammonia diesel dual-fuel working mode automatically, the ammonia injection amount is determined according to calibrated ammonia injection MAP, and if the judgment conditions are not met, the ammonia system cannot work;

along with the reduction of the rotating speed of the internal combustion engine 8, when the working parameters of the engine are separated from the working range of an ammonia system, the electronic control unit 11 can automatically control the diesel ammonia nozzle 2 to stop injecting ammonia; after the engine is stopped, the ammonia system is closed, and the ammonia system can be stopped; the ammonia system is deactivated and the engine can still operate in a pure diesel mode;

when the diesel engine runs in medium and small loads, the electronic control unit 11 reads parameters of the air inlet temperature sensor, controls the opening of the electric control exhaust gas valve, changes the introduction amount of exhaust gas, further adjusts the air inlet temperature to the optimal ammonia evaporation temperature, and improves the heat efficiency;

in a diesel/liquid ammonia dual-fuel working mode, a diesel-ammonia nozzle 2 adopts a twice independent coupling injection strategy; the diesel-ammonia nozzle 2 with the angle of 0-8 degrees before the compression top dead center controls to open and spray high-pressure diesel oil accounting for 2-5% of the compression ratio into the main combustion chamber 3 for compression combustion, the diesel-ammonia nozzle 2 with the angle of 4 degrees before the compression top dead center and 20 degrees after the compression top dead center controls to open and spray liquid ammonia, so that the liquid ammonia is sprayed into flame at the pressure of 600bar to form main fuel combustion, the high-pressure liquid ammonia enters the combustion chamber to quickly absorb heat and flash and is ignited by flame of the diesel combustion to form stable diffusion combustion, thereby improving the difficulty in combustion of the ammonia fuel and solving the problem of reaction, and meanwhile, the ammonia fuel is adopted and has higher octane number than that of the diesel oil, so that the ability of the ammonia fuel to resist knock is better than that of the diesel oil, the internal combustion engine 8 can be allowed to set with higher compression ratio, and further the power density and thermal efficiency of the internal combustion engine 8 are improved, and meanwhile, compared with the existing low-pressure spraying and diffusing combustion mode, the diesel oil substitution rate can be realized, and the carbon reduction of the internal combustion engine can be further widened compared with the low-pressure spraying and premixing combustion mode, the high-spraying and diffusing combustion potential can be obviously reduced by the low-pressure spraying and diffusing combustion mode, the NH3, NOx and greenhouse gas emission discharged by the engine can be obviously reduced;

it should be noted that the internal combustion engine 8 comprises a cylinder cover 1, a cylinder sleeve 4, a piston 5, a connecting rod 6, and a main combustion chamber 3 formed by the cylinder cover 1, the cylinder sleeve 4 and the piston 5, the diesel ammonia nozzle 2 is fixed in the cylinder sleeve 4, the diesel ammonia nozzle 2 is in the prior art, the diesel nozzle and the ammonia nozzle are highly integrated, the arrangement structure of the two nozzles is more compact, and the arrangement space of the cylinder cover 1 is more advantageous;

the ammonia injection MAP is a data graph formed by calibrating the internal combustion engine 8 to obtain fuel injection timing and injection pulse width data under different rotating speeds/loads (power/torque), the entire vehicle VECU receives an accelerator signal and sends an instruction to the engine through a torque model to determine the operation condition of the internal combustion engine 8, and the internal combustion engine 8 injects corresponding fuel based on the MAP graph to further achieve the entire vehicle power demand;

the diesel oil/liquid ammonia dual-fuel working mode refers to that the diesel oil and liquid ammonia are simultaneously or respectively injected by the diesel oil and liquid ammonia nozzle 2.

The diesel-ammonia nozzle 2 adopts a two-time independent coupling injection strategy, namely diesel oil and liquid ammonia are independently injected, the optimal injection combustion mode is that the diesel oil is firstly injected to carry out compression ignition, then a liquid ammonia system is started to start to inject the liquid ammonia, and the liquid ammonia is heated to flash and is ignited by diesel oil combustion flame to form stable diffusion combustion.

In some alternative embodiments: referring to fig. 1 to 2, in the present embodiment, a combustion system of a diesel-fueled high-pressure direct-injection liquid ammonia internal combustion engine is provided, where a pressure sensor connected to an electronic control unit 11 is disposed on each of a diesel rail 16 and a liquid ammonia rail 15 of the combustion system of the diesel-fueled high-pressure direct-injection liquid ammonia internal combustion engine, and a liquid ammonia stop valve 13 is disposed on a connection pipeline between a liquid ammonia tank 7 and a liquid ammonia booster pump 14.

The diesel oil of the combustion system of the diesel oil-ignited high-pressure direct injection liquid ammonia internal combustion engine is provided with the pressure sensors connected with the electronic control unit 11 on the diesel oil rail 16 and the liquid ammonia rail 15, the liquid ammonia stop valve 13 is arranged on the connecting pipeline between the liquid ammonia tank 7 and the liquid ammonia booster pump 14, the pressure sensors serve as the pressure detection units of the diesel oil system and the ammonia system, the pressure sensors are used for being matched with the electronic control unit 11 to make the important basis of the optimal diesel oil and liquid ammonia injection amount, the system control realizes the most efficient diesel oil and ammonia fuel supply proportion in the internal combustion engine 8, and the core that whether energy conservation and emission reduction can be realized finally is achieved.

In some alternative embodiments: referring to fig. 1 to 2, in the combustion system of the diesel-fueled high-pressure direct-injection liquid ammonia internal combustion engine provided in the embodiment of the present application, a plurality of liquid ammonia nozzle holes on a diesel nozzle 2 of the combustion system of the diesel-fueled high-pressure direct-injection liquid ammonia internal combustion engine are circumferentially distributed on the outer side of the diesel nozzle hole, the diameter of the liquid ammonia nozzle hole is greater than 1.5mm, and an included angle between the liquid ammonia nozzle hole and the central axis of the diesel nozzle 2 is 70 ° to 75 °.

The diesel oil high pressure that fires directly spouts liquid ammonia internal-combustion engine combustion system's diesel oil ammonia nozzle 2 highly integrated diesel oil nozzle and ammonia nozzle, there are a plurality of liquid ammonia orifice and diesel oil orifice on the diesel oil ammonia nozzle 2, a plurality of liquid ammonia orifices are the outside of circumference distribution at the diesel oil orifice, the diameter of liquid ammonia orifice is greater than 1.5mm, the contained angle of liquid ammonia orifice and 2 the central axis of diesel oil ammonia nozzle is 70 ~ 75, and then 2 assurance ejecting liquid ammonia of diesel oil ammonia nozzle can the homodisperse come, and the flash of rapid heat absorption in the combustion chamber and ignite by the flame that the diesel oil burnt and form the steady diffusion combustion.

In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as the case may be.

It is noted that, in this application, relational terms such as "first" and "second," and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.

The previous description is only an example of the present application, and is provided to enable any person skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The injection control method of the diesel oil ignition high-pressure direct injection liquid ammonia internal combustion engine is characterized by comprising the following steps of:

when the internal combustion engine (8) is started or is in a small-load working condition, the internal combustion engine (8) runs in a pure diesel mode;

when the internal combustion engine (8) meets the liquid ammonia injection condition and the piston (5) moves to the vicinity of a compression top dead center, controlling a diesel-ammonia nozzle (2) to be opened, and injecting diesel oil and liquid ammonia with preset amounts into a main combustion chamber (3) for compression and combustion;

after the diesel oil is subjected to compression ignition, the liquid ammonia is heated and flashed in the main combustion chamber (3) and is ignited by flame of the diesel oil combustion to form stable diffusion combustion.

2. The injection control method of a diesel-fueled high-pressure liquid ammonia direct injection internal combustion engine according to claim 1, characterized by:

the internal combustion engine (8) meets the liquid ammonia injection conditions of the internal combustion engine rotation speed, the accelerator opening, the air inlet temperature, the coolant temperature and the ammonia liquid level.

3. The injection control method of a diesel pilot high-pressure direct-injection liquid ammonia internal combustion engine as claimed in claim 1, characterized in that:

the diesel-ammonia nozzle (2) injects diesel oil when the piston (5) moves to 0-8 degrees before the compression top dead center.

4. The injection control method of a diesel-fueled high-pressure liquid ammonia direct injection internal combustion engine according to claim 1, characterized by:

the diesel-ammonia nozzle (2) injects liquid ammonia when the piston (5) moves to 4 degrees before the compression top dead center to 20 degrees after the compression top dead center.

5. The injection control method of a diesel pilot high-pressure direct-injection liquid ammonia internal combustion engine as claimed in claim 1, characterized in that:

the total heat value of the diesel oil accounts for 1-10%.

6. The injection control method of a diesel-fueled high-pressure liquid ammonia direct injection internal combustion engine according to claim 1, characterized by:

the total heat value of the diesel oil accounts for 2-5%.

7. The injection control method of a diesel-fueled high-pressure liquid ammonia direct injection internal combustion engine according to claim 1, characterized by:

the injection pressure of the liquid ammonia is not lower than 600bar.

8. Diesel oil ignites high pressure and directly spouts liquid ammonia internal-combustion engine combustion system, its characterized in that includes:

the diesel system comprises a diesel tank (12), the outlet end of the diesel tank (12) is connected with a diesel pump (10) through a pipeline, and the diesel pump (10) is connected with a diesel nozzle (2) positioned in a cylinder of the internal combustion engine through a diesel rail (16);

the ammonia system comprises a liquid ammonia tank (7), the outlet end of the liquid ammonia tank (7) is connected with a liquid ammonia booster pump (14) through a pipeline, and the liquid ammonia booster pump (14) is connected with a diesel ammonia nozzle (2) positioned in a cylinder of the internal combustion engine (8) through a liquid ammonia rail (15);

the diesel-ammonia injection device comprises an electronic control unit (11), wherein a diesel-ammonia nozzle (2) and a liquid ammonia booster pump (14) are connected with the electronic control unit (11), and the electronic control unit (11) is used for controlling the internal combustion engine (8) to start or operate in a pure diesel mode under a small-load working condition;

when the internal combustion engine (8) meets the liquid ammonia injection condition and the piston (5) moves to the position near a compression top dead center, controlling the diesel-ammonia nozzle (2) to be opened, and injecting diesel oil and liquid ammonia with preset amount into the main combustion chamber (3) for compression combustion;

after compression ignition of diesel oil, liquid ammonia is heated and flashed in the main combustion chamber (3) and is ignited by flame generated by combustion of the diesel oil to form stable diffusion combustion.

9. The diesel-fueled high pressure, direct injection, liquid ammonia internal combustion engine combustion system of claim 8, wherein:

all be provided with the pressure sensor who is connected with electronic control unit (11) on diesel rail (16) and liquid ammonia rail (15), be provided with liquid ammonia stop valve (13) on the connecting pipeline between liquid ammonia tank (7) and liquid ammonia booster pump (14).

10. The combustion system of a diesel piloted high pressure direct injection liquid ammonia internal combustion engine as set forth in claim 8, wherein:

a plurality of liquid ammonia orifice on firewood ammonia nozzle (2) are the outside of circumference distribution at the diesel oil orifice, the diameter of liquid ammonia orifice is greater than 1.5mm, the contained angle of liquid ammonia orifice and firewood ammonia nozzle (2) the central axis is 70 ~ 75.