A non-uniform jet prechamber injection system

Abstract

This disclosure provides a non-uniform jet pre-combustion chamber injection system, including: a cylinder head and a cylinder liner, with a combustion chamber defined between the cylinder head and the cylinder liner; a pre-combustion mechanism disposed in the cylinder head, including a housing, with a pre-combustion chamber formed inside the housing, and a first jet hole array, a second jet hole array, and a third jet hole array respectively disposed from top to bottom on the side of the housing facing the combustion chamber; wherein, the first jet hole in the first jet hole array faces the upper part of the combustion chamber, the second jet hole in the second jet hole array faces the center of the combustion chamber, and the third jet hole in the third jet hole array faces the bottom of the combustion chamber.

Description

Technical Field

[0001] This invention relates to the field of engines, and more particularly to a pre-combustion chamber injection system for a non-uniform jet in a compression-ignition ammonia dual-fuel engine. Background Technology

[0002] In compression ignition engines, the compression ratio required to achieve pure ammonia compression ignition is too high (needing to reach 35). Currently, dual-fuel compression ignition is mainly used. This method optimizes the thermal and reactive atmosphere within the combustion chamber by using a highly reactive ignition fuel to achieve ammonia combustion. In this type of dual-fuel engine, research shows that using a pre-combustion chamber structure can increase the initial ignition zone and extend the lean-burn limit.

[0003] However, in the existing pre-combustion chamber structure, the nozzles are uniformly distributed with a consistent orientation. Since the ammonia fuel is fully mixed in the combustion chamber, the combustion jet of a single ignition fuel is difficult to stably ignite the ammonia fuel, and the slow flame propagation speed of the ammonia fuel also leads to a long combustion duration. Summary of the Invention

[0004] In view of this, the present disclosure provides a non-uniform jet pre-combustion chamber injection system, including: a cylinder head and a cylinder liner, with a combustion chamber defined between the cylinder head and the cylinder liner; a pre-combustion mechanism disposed in the cylinder head, including a housing, with a pre-combustion chamber formed inside the housing, and a first jet hole array, a second jet hole array, and a third jet hole array respectively disposed from top to bottom on the side of the housing facing the combustion chamber; wherein, the first jet hole in the first jet hole array faces the upper part of the combustion chamber, the second jet hole in the second jet hole array faces the center of the combustion chamber, and the third jet hole in the third jet hole array faces the bottom of the combustion chamber.

[0005] Optionally, the pre-combustion mechanism also includes a first injector, the output of which is located in the pre-combustion chamber.

[0006] Optionally, the non-uniform jet pre-combustion chamber injection system further includes: a piston disposed within a cylinder liner; at least two ammonia injectors symmetrically disposed within the cylinder liner and located between the top dead center and bottom dead center of the piston.

[0007] Optionally, the first jet hole array includes at least two first jet holes, which are arranged in a row array at equal intervals along the same height; wherein, at least two of the first jet holes in the first jet hole array are configured to have the same aperture.

[0008] Optionally, the second jet orifice includes at least two side jet orifices and at least one intermediate jet orifice. The side jet orifices and the intermediate jet orifice are arranged in a row array at equal intervals along the same height, and the at least two side jet orifices are arranged symmetrically about the intermediate jet orifice.

[0009] Optionally, at least some of the two side jet holes are set to have the same diameter; the diameter of the middle jet hole is set to be larger than the diameter of the two side jet holes.

[0010] Optionally, the diameter of the first jet orifice is set to 1 / 3 to 1 / 2 of the diameter of the two jet orifices.

[0011] Optionally, the third jet orifice array includes at least two third jet orifices, which are arranged in a row array at equal intervals along the same height; at least some of the third jet orifices have the same orifice diameter, and the total jet flow rate of the third jet orifice array is set to be the same as that of the first jet orifice array.

[0012] Optionally, the diameter of the third jet orifice is set to be larger than the diameter of the first jet orifice, and the number of the third jet orifice is set to be less than the number of the first jet orifice.

[0013] Optionally, the non-uniform jet pre-combustion chamber injection system also includes an exhaust valve located in the cylinder head.

[0014] According to the non-uniform jet pre-combustion chamber injection system provided in this disclosure, by arranging the first jet orifice array, the second jet orifice array, and the third jet orifice array from top to bottom on the housing of the pre-combustion mechanism, multiple combustion jets can be injected to ignite ammonia fuel, enabling the ammonia fuel to burn simultaneously in multiple locations within the combustion chamber. This effectively reduces the negative impacts on engine efficiency caused by the difficulty of compression ignition of ammonia fuel, the slow propagation speed of the combustion flame, and the long combustion duration. Due to the uneven distribution of ammonia fuel concentration and turbulent kinetic energy within the combustion chamber, by setting the first jet orifice towards the upper part of the combustion chamber, the second jet orifice towards the center of the combustion chamber, and the third jet orifice towards the bottom of the combustion chamber, corresponding combustion jets can be injected towards different areas within the combustion chamber. This allows the ammonia fuel in different areas to achieve matching ignition conditions, effectively improving ignition efficiency and promoting stable ignition of ammonia fuel, thereby enhancing the overall energy utilization efficiency of the engine. Attached Figure Description

[0015] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0016] Figure 1 A schematic cross-sectional view of a pre-combustion chamber injection system with a non-uniform jet according to an embodiment of the present disclosure is shown.

[0017] Figure 2 A schematic diagram of a combustion jet injection according to an embodiment of the present disclosure is shown;

[0018] Figure 3 The diagram schematically illustrates the concentration distribution of ammonia fuel in a combustion chamber according to an embodiment of the present disclosure;

[0019] Figure 4 The diagram schematically illustrates the turbulent kinetic energy distribution of ammonia fuel in a combustion chamber according to an embodiment of the present disclosure.

[0020] In the accompanying drawings, the meanings of the reference numerals are as follows:

[0021] 1-Exhaust valve;

[0022] 2-Cylinder liner;

[0023] 3-Ammonia injector;

[0024] 4-Piston;

[0025] 5-First injector;

[0026] 6-Shell;

[0027] 7-Cylinder head;

[0028] 8-Combustion chamber;

[0029] 9-First jet orifice array; 91-First jet orifice;

[0030] 10 - Second jet orifice array; 101 - Second jet orifice; 1011 - Side jet orifices; 1012 - Middle jet orifice;

[0031] 11-Third jet hole array; 111-Third jet hole. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0034] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0035] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0036] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this disclosure.

[0037] This disclosure provides a non-uniform jet pre-combustion chamber injection system that can be applied to a compression-ignition ammonia dual-fuel engine, wherein the dual fuels are ammonia fuel and an ignition fuel, and the combustion of the ignition fuel helps to achieve the combustion of the ammonia fuel, thereby providing power to the engine.

[0038] Figure 1 A schematic cross-sectional view of a pre-combustion chamber injection system with a non-uniform jet according to an embodiment of the present disclosure is shown.

[0039] According to the pre-combustion chamber injection system provided in this disclosure, such as Figure 1 As shown, the non-uniform jet pre-combustion chamber injection system includes: a cylinder head 7 and a cylinder liner 2, with a combustion chamber 8 defined between the cylinder head 7 and the cylinder liner 2; a pre-combustion mechanism, disposed in the cylinder head 7, including a housing 6, within which a pre-combustion chamber is formed; furthermore, a first jet hole array 9, a second jet hole array 10, and a third jet hole array 11 are respectively arranged from top to bottom on the side of the housing 6 facing the combustion chamber 8. Specifically, the first jet hole 91 in the first jet hole array 9 faces the upper part of the combustion chamber 8, the second jet hole 101 in the second jet hole array 10 faces the center of the combustion chamber 8, and the third jet hole 111 in the third jet hole array 11 faces the bottom of the combustion chamber 8.

[0040] Specifically, in compression-ignition engines, the auto-ignition temperature of ammonia fuel is as high as 651°C, far exceeding that of diesel (210°C) and gasoline (427°C), and even higher than that of hydrogen (500°C). For ammonia fuel to auto-ignite in a compression-ignition engine, the compression ratio needs to be increased to above 35 to raise the temperature inside the combustion chamber to above 651°C. In some embodiments, by adding a small amount of ignition fuel to the ammonia fuel to lower the auto-ignition temperature of the mixed fuel (ammonia fuel and ignition fuel), the required compression ratio of the engine can be reduced. The ignition fuel can be hydrogen, diesel, methanol, etc. For example, an ammonia-hydrogen mixed fuel can reduce the compression ratio to 20-25.

[0041] Furthermore, the cylinder liner 2 is cylindrical, and the bottom plane of the cylinder head 7 is tightly fitted with the upper end face of the cylinder liner 2, forming the top boundary of the combustion chamber 8, which provides space for the combustion of ammonia fuel. Further, the pre-combustion chamber provides combustion space for the ignition fuel. One side of the housing 6 is tightly fitted with the side of the cylinder head 7, and part of the housing 6 penetrates the cylinder head 7 and is embedded inside the combustion chamber 8. The portion of the housing 6 located inside the combustion chamber 8 forms an injection surface, which is an arc-shaped curved surface whose normal direction coincides with the center line of the housing 6. The pre-combustion chamber inside the housing 6 is connected to the combustion chamber 8 through the first jet hole array 9, the second jet hole array 10, and the third jet hole array 11 set on the injection surface, which can divide the combustion products of the ignition fuel into multiple jets (i.e., form multiple combustion jets) and inject them into different areas within the combustion chamber 8.

[0042] Figure 2 A schematic diagram of a combustion jet injection according to an embodiment of the present disclosure is shown.

[0043] like Figure 2 As shown, the combustion jet generated in the pre-combustion chamber is divided into multiple beams and injected into the combustion chamber 8 through the first jet hole 91 in the first jet hole array 9, the second jet hole 101 in the second jet hole array 10, and the third jet hole 111 in the third jet hole array 11.

[0044] Figure 3 The diagram schematically illustrates the concentration distribution of ammonia fuel in a combustion chamber according to an embodiment of the present disclosure. Figure 4 The diagram schematically illustrates the turbulent kinetic energy distribution of ammonia fuel in a combustion chamber according to an embodiment of the present disclosure.

[0045] like Figure 3As shown, the ammonia fuel concentration is represented by a color gradient. Darker colors (such as purple) indicate lower concentrations (close to 0), while lighter colors (such as yellow) indicate higher concentrations (up to 0.3, dimensionless), reflecting the uneven distribution of concentration within the combustion chamber. As shown in Figure 4, the color changes from blue to red. Blue areas have lower turbulent kinetic energy (e.g., 2 m² / s²), while red areas have higher turbulent kinetic energy (e.g., 30 m² / s²), demonstrating regional differences in turbulent kinetic energy. Therefore, the concentration and turbulent kinetic energy of ammonia fuel vary in different regions of combustion chamber 8. The ignition conditions for ammonia fuel (such as local fuel concentration, temperature, and turbulence intensity) are jointly determined by the concentration field and the turbulent kinetic energy field. For example, regions with high turbulent kinetic energy, if accompanied by a higher ammonia fuel concentration, can optimize the mixing effect and promote a more complete combustion reaction.

[0046] Furthermore, by setting the first jet hole 91 in the first jet hole array 9 to face the upper part of the combustion chamber 8, the second jet hole 101 in the second jet hole array 10 to face the center of the combustion chamber 8, and the third jet hole 111 in the third jet hole array 11 to face the bottom of the combustion chamber 8, the specific distribution of multiple combustion jets can be achieved, and corresponding combustion jets can be sprayed to achieve matching ignition conditions. For example, in the central region of combustion chamber 8, the ammonia fuel concentration is high and it also exhibits high turbulent kinetic energy. This indicates that there is a large quantity of ammonia fuel in the central region of combustion chamber 8, and the mixing and heat transfer efficiency are high. By setting the second jet hole 101 in the second jet hole array 10 towards the center of combustion chamber 8, this part of the combustion jet can be injected and the combustion wave can be rapidly diffused by turbulence, making it easy to achieve global ignition. In the upper part of combustion chamber 8, the ammonia fuel concentration is low but the turbulent kinetic energy is high. By setting the first jet hole 91 in the first jet hole array 9 towards the upper part of combustion chamber 8, this part of the combustion jet can also be injected and ignited quickly by turbulence. At the same time, the amount of combustion jet used can be reduced accordingly to reduce the waste of ignition fuel. In the bottom of combustion chamber 8, the ammonia fuel concentration is not high and the turbulent kinetic energy is low. Therefore, it is necessary to set the third jet hole 111 in the third jet hole array 11 towards the bottom of combustion chamber 8 to distribute sufficient combustion jet.

[0047] In this embodiment, by arranging the first jet orifice array 9, the second jet orifice array 10, and the third jet orifice array 11 from top to bottom on the housing 6 of the pre-combustion mechanism, multiple combustion jets can be sprayed to ignite ammonia fuel, allowing the ammonia fuel to burn simultaneously in multiple locations within the combustion chamber 8. This effectively reduces the negative impacts on engine efficiency caused by the difficulty of compression ignition of ammonia fuel, the slow propagation speed of the combustion flame, and the long combustion duration. Due to the uneven distribution of ammonia fuel concentration and turbulent kinetic energy within the combustion chamber 8, by setting the first jet orifice 91 towards the top of the combustion chamber 8, the second jet orifice 101 towards the center of the combustion chamber 8, and the third jet orifice 111 towards the bottom of the combustion chamber 8, corresponding combustion jets can be sprayed towards different areas within the combustion chamber 8. This allows ammonia fuels of different concentrations and turbulent kinetic energies to achieve matching ignition conditions, effectively improving ignition efficiency and promoting stable ignition of ammonia fuel. This also enhances the overall energy utilization efficiency of the engine.

[0048] like Figure 1 As shown, according to an embodiment of the present disclosure, the pre-combustion mechanism further includes a first injector 5, the output end of which is located in the pre-combustion chamber.

[0049] Furthermore, the first injector 5 is generally slender and cylindrical. One end of the first injector 5 is vertically installed on the side wall of the housing 6 exposed outside the cylinder head 7 (i.e., the outer side wall opposite to the part of the housing 6 embedded in the cylinder head 7). The output end of the first injector 5 passes through this side wall and connects to the interior of the pre-combustion chamber to inject the ignition fuel into the pre-combustion chamber. The output end of the first injector 5 is directly facing the central area inside the pre-combustion chamber, so that the injected ignition fuel can be evenly diffused radially into the space of the pre-combustion chamber (i.e., it is distributed radially in all directions with the output end of the first injector 5 as the center).

[0050] Specifically, in some embodiments, in the pre-combustion chamber, the ignition fuel is thoroughly mixed with air to form a combustible mixture. For ignition fuels suitable for compression ignition, such as diesel, after the combustible mixture is formed, the pre-combustion chamber intensely compresses the mixture during the compression stroke, causing a rapid increase in temperature and pressure. When the auto-ignition temperature of the ignition fuel is reached, the fuel burns rapidly in the pre-combustion chamber. Due to the relatively small space of the pre-combustion chamber, the combustion process can reach high temperatures and pressures in a short time. The heat generated by combustion causes the gas in the pre-combustion chamber to expand rapidly, forming high-temperature and high-pressure combustion products, including flames, free radicals, and incompletely burned mixtures. The high-temperature and high-pressure combustion products formed in the pre-combustion chamber are injected into the combustion chamber 8 in the form of high-speed jets through the first jet orifice array 9, the second jet orifice array 10, and the third jet orifice array 11. After the combustion jet enters the combustion chamber 8, the ignition fuel it carries forms a mixed fuel with the ammonia fuel. Because the combustion jet has strong energy and activity, it can form multiple ignition sources in the combustion chamber 8, thereby accelerating the ignition speed of the mixed fuel in the combustion chamber 8 and helping to quickly achieve the combustion of the ammonia fuel.

[0051] In this implementation, the pre-combustion chamber first burns the ignition fuel in a small space to generate a combustion jet, thereby triggering the combustion in the combustion chamber 8. This creates favorable conditions for combustion in the combustion chamber 8. Through the propagation and ignition effect of the combustion jet, the ignition environment in the combustion chamber 8 can be improved, and the ignition and combustion of ammonia fuel can be accelerated.

[0052] like Figure 1 As shown, according to an embodiment of this disclosure, the non-uniform jet pre-combustion chamber injection system further includes a piston 4 and at least two ammonia injectors 3. The piston 4 is disposed within a cylinder liner 2. The at least two ammonia injectors 3 are symmetrically disposed in the cylinder liner 2 and located between the top dead center and bottom dead center of the piston 4.

[0053] Specifically, piston 4 is cylindrical and fits snugly against the inner wall of cylinder liner 2. Piston ring grooves are provided on the outer surface of piston 4 to seal combustion chamber 8 and reduce friction. The top of piston 4 is designed as a shallow concave or flat-top shape, and the axis of piston 4 is completely aligned with the axis of cylinder liner 2. Piston 4 can reciprocate linearly within cylinder liner 2. Top dead center is when the top surface of piston 4 and the bottom surface of cylinder head 7 (i.e., the top boundary of combustion chamber 8) form the minimum compression space, and bottom dead center is when piston 4 descends to near the bottom of cylinder liner 2.

[0054] Specifically, at least two ammonia injectors 3 are elongated tubular in shape, injecting ammonia fuel into the combustion chamber 8. The ammonia fuel (injected in liquid or gaseous form) combines with air in the combustion chamber 8 to form the combustible gas. The at least two ammonia injectors 3 are arranged circumferentially along the cylinder liner 2. Further, when there are two ammonia injectors 3, they are symmetrically distributed along the diameter of the cylinder liner 2 at an angle of 180°, ensuring that the ammonia fuel is injected from both sides of the combustion chamber 8, forming a counter-current injection flow field; if there are three ammonia injectors 3, they are evenly distributed around the circumference of the cylinder liner 2 at 120° intervals, and the ammonia fuel injected by the three ammonia injectors 3 diffuses radially within the combustion chamber 8; if four ammonia injectors 3 are used, the four ammonia injectors 3 are evenly distributed circumferentially along the cylinder liner 2, with adjacent ammonia injectors 3 at an angle of 90°, forming a cross-shaped injection layout, so that the ammonia fuel is injected into the combustion chamber 8 in a symmetrical jet form. At least two ammonia injectors 3 are located approximately 1 / 3 to 1 / 2 of the combustion chamber height below the top dead center of the piston 4, i.e., near the upper part of the combustion chamber 8. This position ensures that the ammonia fuel is injected at the beginning of the piston's upward compression stroke, allowing sufficient time to mix with air and form a uniform combustion gas. It also avoids uneven local concentration caused by ammonia fuel being injected near the cylinder head 7 due to an excessively high position, or poor mixing of ammonia fuel and air due to premature injection during the piston's downward stroke due to an excessively low position. Specifically, after liquid ammonia fuel is injected, it forms an atomized cone with a cone angle of 30°-60°, and after gaseous ammonia fuel is injected, it forms a fan-shaped diffusion flow. This flow couples with the vortex generated during the upward compression of the piston 4, promoting uniform mixing of ammonia fuel and air within the combustion chamber 8.

[0055] In some embodiments, the piston 4, driven by a crankshaft connecting rod mechanism, moves from bottom dead center to top dead center. As it moves, the volume of the combustion chamber 8 gradually decreases, forcing the gas to be burned within the combustion chamber 8 to be compressed. The upward movement of the piston 4 increases the pressure of the gas to be burned within the combustion chamber 8, leading to an increase in the internal energy of the gas, manifested as an increase in the temperature and pressure of the gas. Furthermore, a low-pressure injection mode can be adopted depending on the timing of the combustion jet injection. In this mode, the ammonia injector 3 injects ammonia fuel circumferentially from the cylinder liner 2 during the compression stroke of the piston 4. This allows the ammonia fuel more time to fully mix with air. For example, low-pressure injection of liquid ammonia during the intake stroke enhances the vaporization, diffusion, and entrainment processes of the liquid ammonia jet through the synergistic effects of its impact, adhesion, and reflection flow, thereby increasing the mixing rate between the ammonia fuel and air. When the piston 4 moves to near top dead center, the pre-combustion chamber injects a combustion jet into the combustion chamber 8, which triggers the ignition of the gas to be burned.

[0056] In this implementation, the compression of piston 4 creates favorable conditions for the ignition of the combustion jet, promotes the ignition of ammonia fuel, and also makes the mixing concentration of ammonia fuel and air in combustion chamber 8 more uniform, which is conducive to achieving more complete combustion of ammonia fuel and reducing the emission of incomplete combustion products.

[0057] like Figure 1 As shown, according to an embodiment of this disclosure, the non-uniform jet pre-combustion chamber injection system further includes an exhaust valve 1. The exhaust valve 1 is disposed on the cylinder head 7.

[0058] Specifically, the exhaust valve 1 is installed through a pre-drilled valve hole on the top of the cylinder head 7. The axis of the valve hole is perpendicular to the upper surface of the cylinder head 7. The exhaust valve 1 has a disc-shaped structure and is made of high-temperature resistant alloy material. The main body consists of a valve disc and a valve stem. The surface of the valve disc is flat and smooth, and the edge is provided with a sealing cone surface. When the valve disc is inserted into the valve hole, this sealing cone surface fits tightly with the valve seat on the inner wall of the valve hole to achieve the sealing function. The valve stem is vertically fixed to the center of the valve disc, is slender and cylindrical, and extends to the outside of the cylinder head 7 for easy connection with the drive mechanism.

[0059] Furthermore, the exhaust valve 1 is positioned close to the edge of the combustion chamber 8 and maintains a certain distance from the pre-combustion chamber to ensure that the exhaust process does not interfere with the combustion process within the pre-combustion chamber. Simultaneously, this position ensures that the exhaust gas in the combustion chamber 8 is smoothly discharged through the exhaust valve 1 when the piston reaches its exhaust stroke. Specifically, when the exhaust valve 1 is closed, the valve disc tightly adheres to the valve seat, preventing leakage of high-temperature, high-pressure gas from the combustion chamber 8; when the exhaust valve 1 is open, the upward movement of the valve stem causes the valve disc to move away from the valve seat, forming an annular exhaust channel for efficient exhaust gas discharge. Since the exhaust gas from ammonia fuel combustion may contain corrosive substances, the exhaust valve 1 can be made of corrosion-resistant materials (including but not limited to nickel-based alloys).

[0060] In some embodiments, when piston 4 reaches the bottom dead center of the power stroke and moves upward, exhaust valve 1 opens at the correct time (or may open earlier at the end of the expansion stroke). This allows for the rapid discharge of most of the exhaust gas during the free exhaust phase, utilizing the exhaust gas pressure (higher than atmospheric pressure) within combustion chamber 8. Subsequently, a forced exhaust phase begins, where piston 4 forces the remaining exhaust gas out of combustion chamber 8. Specifically, after the combustion jet generated in the pre-combustion chamber triggers ignition in combustion chamber 8, the exhaust gas within combustion chamber 8 may contain unreacted ammonia, intermediate products, and pollutants. The rapid opening of exhaust valve 1 reduces the residence time of high-temperature exhaust gas within combustion chamber 8, thus inhibiting the formation of pollutants. If unburned areas exist within combustion chamber 8 (such as areas with low-concentration ammonia fuel), the flow area and opening pattern of exhaust valve 1 must ensure that exhaust gas in these areas is effectively discharged, preventing residual exhaust gas from diluting the gas to be burned in the next cycle.

[0061] Furthermore, during the compression stroke, exhaust valve 1 remains closed, and piston 4 moves upward to compress the gas to be burned, increasing the pressure and temperature inside combustion chamber 8, creating conditions for the combustion jet to trigger ignition. The exhaust valve 1 can close with a delay after the top dead center of the exhaust stroke, utilizing the inertia of the exhaust flow to "suck" in residual exhaust gas.

[0062] In this implementation, by opening / closing the exhaust valve 1 at the correct time, efficient exhaust gas discharge and good sealing of the combustion chamber 8 can be ensured, providing a favorable environment for the combustion jet to trigger ignition.

[0063] like Figures 2-4 As shown, according to an embodiment of this disclosure, the first jet hole array 9 includes at least two first jet holes 91, which are arranged in a row array at equal intervals along the same height. The at least two first jet holes 91 in the first jet hole array 9 are configured to have the same aperture.

[0064] Furthermore, the injection surface of the housing 6 can be formed as part of a hemispherical surface and employ three first jet holes 91. Specifically, the three first jet holes 91 are evenly distributed along the circumferential direction of the injection surface, ensuring that multiple combustion jets can be injected into the combustion chamber 8 in a divergent but symmetrical manner. The axes of the three first jet holes 91 are all perpendicular to the tangent of their respective injection surfaces, ensuring that the combustion jets are injected at high speed through the most direct path to the upper part of the combustion chamber 8. In addition, the three first jet holes 91 are all located in a space region 5-8 mm above the top dead center of the piston 4, which can prevent the combustion jets from directly impacting the top of the piston 4, reducing the thermal load and mechanical stress on the piston 4.

[0065] In this implementation, the placement of the first jet orifice 91 takes advantage of the relatively uniform concentration and turbulent kinetic energy distribution of ammonia fuel in the upper region of the combustion chamber 8. The combustion jets ejected from the first jet orifice array 9 are distributed in a fan shape. The identical orifice diameter ensures the consistency of flow rate and velocity of each combustion jet, allowing the combustion products of the ignition fuel to diffuse uniformly within the combustion chamber 8, thus improving the stability of the ammonia fuel combustion process in the upper region of the combustion chamber 8. Furthermore, when three first jet orifices 91 are used to form three combustion jets, a stable triangular energy distribution region can be constructed within the combustion chamber 8, achieving efficient coverage of the upper region of the combustion chamber 8.

[0066] Furthermore, in some embodiments, such as when the ammonia fuel and air are not sufficiently mixed near the wall of the combustion chamber 8, a high-momentum jet is needed to break the stratification and promote mixing. In this case, the aperture of the first jet hole 91 at the corresponding position can be increased to improve the jet momentum and enhance the entrainment capacity of the ammonia fuel near the wall.

[0067] like Figures 1-4 As shown, according to the embodiments of this disclosure, after the ammonia fuel is injected by the ammonia injector 3, the ammonia fuel diffuses with the movement of the piston 4. During the diffusion process, the ammonia fuel mainly concentrates in the central region of the combustion chamber 8, resulting in a high ammonia fuel concentration and high turbulent kinetic energy in this region. However, unlike the upper region of the combustion chamber 8, the concentration and turbulent kinetic energy of the ammonia fuel in the central region of the combustion chamber 8 exhibit a significantly uneven distribution. Therefore, it is necessary to further subdivide the second jet orifice 101 in the second jet orifice array 10 based on this characteristic. Specifically, as... Figure 2 As shown, the second jet orifice 101 includes at least two side jet orifices 1011 and at least one intermediate jet orifice 1012. The side jet orifices 1011 and the intermediate jet orifice 1012 are arranged in a row array, with equal spacing at the same height, and at least two side jet orifices 1011 are arranged symmetrically about the intermediate jet orifice 1012. Furthermore, since the concentration and turbulent kinetic energy of ammonia fuel at the two sides of the central region within the combustion chamber 8 are similar, at least some of the side jet orifices 1011 have the same orifice diameter. Further, as... Figure 3 As shown, the concentration of ammonia fuel in the central region of combustion chamber 8 is lower on both sides than in the middle. Meanwhile, as... Figure 4 As shown, the turbulent kinetic energy of ammonia fuel in the central region of combustion chamber 8 is lower on both sides than in the middle. Therefore, the diameter of the central jet orifice 1012 is larger than the diameters of the two side jet orifices 1011. By further comparing the numerical relationship between the concentration and turbulent kinetic energy in the upper and central regions of combustion chamber 8, the diameter relationship between the first jet orifice 91 and the second jet orifice 101 can be further adjusted accordingly. For example, as... Figure 3As shown, the concentration value in the upper region of the combustion chamber 8 is 1 / 3 to 1 / 2 of the concentration value on both sides of the central region. Based on this characteristic, the diameter of the first jet hole 91 can be set to 1 / 3 to 1 / 2 of the diameter of the two jet holes 1011.

[0068] Furthermore, in some embodiments, a central jet hole 1012 may be set at the center of the second jet hole array 10, and two side jet holes may be set. The axes of the central jet hole 1012 and the side jet holes 1011 are all perpendicular to the cross-section of the spray surface.

[0069] Furthermore, in some embodiments, the aperture size relationship can also be determined by comparing other parameters, including but not limited to the concentration fluctuation coefficient (the ratio of the standard deviation to the mean of ammonia fuel concentration in each region of the combustion chamber 8 is used to characterize the degree of concentration non-uniformity) and the "combustion potential index" (the product of concentration, turbulent kinetic energy and temperature).

[0070] In this implementation, on the one hand, a combustion jet with a larger flow rate is allocated to the central position of the ammonia fuel in the central region of the combustion chamber 8, taking into account its high concentration and high turbulent kinetic energy. This combustion jet carries more ignition fuel, thereby providing stronger ignition energy to the central position of the combustion chamber 8, enabling rapid ignition and complete combustion, improving ignition efficiency, and avoiding the waste caused by the underutilization of ignition fuel on both sides of the central region of the combustion chamber 8. On the other hand, the flow rate relationship between the multiple combustion jets obtained in the upper and central regions of the combustion chamber 8 is further clarified. The allocation of ignition fuel takes into account the actual amount of ammonia fuel at different positions in the combustion chamber 8, resulting in a more uniform fuel mixture and a more stable combustion process in the upper and central regions of the combustion chamber 8.

[0071] like Figures 2-4 As shown, according to the embodiments of this disclosure, since the concentration and turbulent kinetic energy distribution of ammonia fuel at the bottom of combustion chamber 8 are relatively uniform, the third jet orifice array 11 includes at least two third jet orifices 111. These at least two third jet orifices 111 are arranged in a row array, with equal spacing at the same height, so that combustion jets are obtained at different positions at the bottom of combustion chamber 8. Furthermore, at least some of the third jet orifices 111 have the same orifice diameter, ensuring that most positions at the bottom of combustion chamber 8 receive combustion jets with consistent flow rates. Furthermore, since the amount of ammonia fuel distributed in the upper and lower regions of combustion chamber 8 is similar, the total injection flow rate of the third jet orifice array 11 is set to be the same as the total injection flow rate of the first jet orifice array 9. Furthermore, the orifice diameter of the third jet orifice 111 can be set to be larger than the orifice diameter of the first jet orifice 91, and the number of third jet orifices 111 can be set to be less than the number of first jet orifices 91.

[0072] Specifically, in some embodiments, during engine combustion, if the amount of ammonia fuel and ignition fuel differs significantly between the upper and lower regions of the combustion chamber 8, such as intense combustion in the upper region and insufficient combustion in the lower region, a localized high-temperature region is easily formed at the cylinder head 7 or piston 4. The material of the cylinder head 7 or piston 4 may experience alternating thermal stress due to inconsistent thermal expansion between the high-temperature and low-temperature regions, which can easily lead to fatigue cracks during long-term operation. Therefore, the total injection flow rate of the third jet orifice array 11 needs to be the same as the total injection flow rate of the first jet orifice array 9. Furthermore, when three first jet orifices 91 are provided, the number of third jet orifices 111 can be set to two to allow the third jet orifices 111 to adopt a larger aperture, wherein the axes of both third jet orifices 111 are perpendicular to the tangential surface of their respective injection surfaces.

[0073] In this implementation, on the one hand, the uniform distribution of ignition fuel in the bottom region of the combustion chamber 8 improves the stability of the ammonia fuel combustion process in the bottom region of the combustion chamber 8. At the same time, the equal amount of combustion in the upper and lower regions of the combustion chamber 8 makes the heat load distribution of the cylinder head 7 or piston 4 more uniform, avoiding material fatigue caused by local overheating and extending the service life of the engine. On the other hand, by reducing the number and increasing the diameter of the third jet holes 111, the combustion jet injected toward the bottom of the combustion chamber 8 has greater momentum and higher temperature. This can increase the local temperature while entraining the surrounding gases to be burned, ensuring complete combustion at the bottom, reducing afterburning losses during the upward movement of the piston 4, and further improving thermal efficiency.

[0074] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A prechamber injection system of non-uniform jet flow, characterized in that, include: Cylinder head (7) and cylinder liner (2), wherein a combustion chamber (8) is defined between the cylinder head (7) and cylinder liner (2); A pre-combustion mechanism, disposed in the cylinder head (7), includes: The housing (6) has a pre-combustion chamber inside it. The housing is provided with a first jet hole array (9), a second jet hole array (10) and a third jet hole array (11) from top to bottom on the side of the housing facing the combustion chamber (8). In this configuration, the first jet hole (91) in the first jet hole array (9) faces the upper part of the combustion chamber (8), the second jet hole (101) in the second jet hole array (10) faces the center of the combustion chamber (8), and the third jet hole (111) in the third jet hole array (11) faces the bottom of the combustion chamber (8). The first jet hole array (9) includes at least two first jet holes (91), which are arranged in a row array at equal intervals along the same height. The at least two first jet holes (91) in the first jet hole array (9) are configured to have the same aperture. The second jet hole (101) includes at least two side jet holes (1011) and at least one middle jet hole (1012), wherein the side jet holes (1011) and the middle jet hole (1012) are... The third jet hole array (11) is arranged in a row array with equal spacing at the same height, and at least two of the two side jet holes (1011) are arranged symmetrically with the middle jet hole (1012) as the center; at least some of the two side jet holes (1011) have the same diameter, and the diameter of the middle jet hole (1012) is larger than that of the two side jet holes (1011); the third jet hole array (11) includes at least two third jet holes (111), which are arranged in a row array with equal spacing at the same height; at least some of the third jet holes (111) have the same diameter, and the total jet flow rate of the third jet hole array (11) is the same as that of the first jet hole array (9).

2. The pre-chamber injection system of claim 1, wherein, The pre-combustion mechanism also includes a first injector (5), the output end of which is located in the pre-combustion chamber.

3. The system according to claim 1, characterized in that, Also includes: Piston (4) is disposed inside cylinder liner (2); At least two ammonia injectors (3) are symmetrically arranged on the cylinder liner (2) and located between the top dead center and bottom dead center of the piston (4).

4. The system according to claim 1, characterized in that, The diameter of the first jet hole (91) is set to 1 / 3 to 1 / 2 of the diameter of the two jet holes (1011).

5. The system according to claim 1, characterized in that, The diameter of the third jet hole (111) is set to be larger than the diameter of the first jet hole (91), and the number of the third jet holes (111) is set to be less than the number of the first jet holes (91).

6. The system according to claim 1, characterized in that, Also includes: An exhaust valve (1) is provided on the cylinder head (7).

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