Pre-combustion chamber injection system with non-uniform jet flow

Abstract

The invention provides a non-uniform jet flow pre-combustion chamber injection system which comprises a cylinder cover and a cylinder sleeve, and a combustion chamber is defined between the cylinder cover and the cylinder sleeve; the pre-combustion mechanism is arranged on the cylinder cover and comprises a shell, a pre-combustion chamber is formed in the shell, and a first jet hole array, a second jet hole array and a third jet hole array are arranged on the side, facing the combustion chamber, of the shell from top to bottom; wherein first jet flow holes in the first jet flow hole array face the upper portion of the combustion chamber, second jet flow holes in the second jet flow hole array face the center of the combustion chamber, and third jet flow holes in the third jet flow hole array face the bottom of the combustion chamber.

Description

Technical Field

[0001] The present invention relates to the field of engines, and in particular to a pre-combustion chamber injection system with non-uniform jet applied to a compression-ignition ammonia dual-fuel engine. Background Art

[0002] In compression-ignition engines, because the compression ratio required to achieve pure ammonia compression ignition is too high (requiring a compression ratio of 35), a dual-fuel compression ignition method is currently used. This method optimizes the thermal and reactive atmosphere within the combustion chamber by burning a highly reactive pilot fuel, enabling combustion of the ammonia fuel. Research has shown that the use of a pre-combustion chamber in this dual-fuel engine can increase the initial ignition zone and extend the lean-burn limit.

[0003] However, in the existing pre-combustion chamber structure, the nozzles are evenly distributed in the same direction. Since the ammonia fuel is fully mixed in the combustion chamber, a single combustion jet of the pilot fuel is difficult to stably ignite the ammonia fuel, and the slower 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 pre-combustion chamber injection system with non-uniform jets, comprising: a cylinder head and a cylinder liner, wherein a combustion chamber is defined between the cylinder head and the cylinder liner; a pre-combustion mechanism, arranged in the cylinder head, comprising a shell, wherein a pre-combustion chamber is formed in the shell, and a first jet hole array, a second jet hole array and a third jet hole array are respectively provided on the side of the shell facing the combustion chamber from top to bottom; 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 further includes a first injector, and an output end of the first injector is located in the pre-combustion chamber.

[0006] Optionally, the non-uniform jet pre-combustion chamber injection system further includes: a piston disposed in a cylinder liner; at least two ammonia injectors, which are symmetrically disposed in the cylinder liner and located between the top dead center and the 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 first jet holes in the first jet hole array are configured to have the same aperture.

[0008] Optionally, the second jet holes include at least two side jet holes and at least one middle jet hole, wherein the side jet holes and the middle jet hole are arranged in a row array at equal intervals along the same height, and the at least two side jet holes are symmetrically arranged with the middle jet hole as the center.

[0009] Optionally, the apertures of at least some of the jet holes on both sides are set to be the same; and the aperture of the middle jet hole is set to be larger than the apertures of the jet holes on both sides.

[0010] Optionally, the aperture of the first jet hole is set to 1 / 3 to 1 / 2 of the apertures of the jet holes on both sides.

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

[0012] Optionally, the aperture of the third jet hole is set to be larger than the aperture of the first jet hole, and the number of the third jet holes is set to be smaller than the number of the first jet holes.

[0013] Optionally, the non-uniform jet pre-combustion chamber injection system further includes: an exhaust valve, which is arranged on the cylinder head.

[0014] According to the non-uniform jet pre-combustion chamber injection system provided by the present invention, by arranging the first jet hole array, the second jet hole array and the third jet hole array from top to bottom on the shell of the pre-combustion mechanism, multiple combustion jets can be sprayed to ignite the ammonia fuel, so that the ammonia fuel burns simultaneously in multiple places in the combustion chamber, effectively reducing the negative impact of the difficulty of compression ignition of the ammonia fuel, the slow propagation speed of the combustion flame and the long combustion duration on the engine efficiency; since the concentration and turbulent kinetic energy of the ammonia fuel in the combustion chamber are unevenly distributed, by arranging the first jet hole toward the upper part of the combustion chamber, the second jet hole toward the center of the combustion chamber, and the third jet hole toward the bottom of the combustion chamber, corresponding combustion jets can be sprayed toward different areas in the combustion chamber, so that the ammonia fuel in different areas reaches matching ignition conditions, effectively improving the ignition efficiency and promoting the stable ignition of the ammonia fuel, and also improving the overall energy utilization efficiency of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0016] Figure 1 A front cross-sectional view schematically illustrates a pre-combustion chamber injection system with a non-uniform jet according to an embodiment of the present disclosure;

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

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

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

[0020] In the 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 ejector;

[0026] 6- housing;

[0027] 7-cylinder head;

[0028] 8- Combustion chamber;

[0029] 9-first jet hole array; 91-first jet hole;

[0030] 10-second jet hole array; 101-second jet hole; 1011-two side jet holes; 1012-middle jet hole;

[0031] 11-third jet hole array; 111-third jet hole. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0033] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. 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 should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0035] When expressions such as “at least one of A, B, and C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those 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, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc. When expressions such as “at least one of A, B, or C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those 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, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.

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

[0037] The present 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 pilot fuel, wherein the combustion of the pilot fuel helps to achieve the combustion of the ammonia fuel, and the combustion of the ammonia fuel provides power to the engine.

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

[0039] According to the pre-combustion chamber injection system provided by the present disclosure, Figure 1 As shown, the pre-combustion chamber injection system for non-uniform jets 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, which is arranged in the cylinder head 7 and includes a shell 6, with a pre-combustion chamber formed therein; further, 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 shell 6 facing the combustion chamber 8. Specifically, the first jet hole 91 in the first jet hole array 9 is arranged toward the upper part of the combustion chamber 8, the second jet hole 101 in the second jet hole array 10 is arranged toward the center of the combustion chamber 8, and the third jet hole 111 in the third jet hole array 11 is arranged toward the bottom of the combustion chamber 8.

[0040] Specifically, in a compression-ignition engine, the auto-ignition temperature of ammonia fuel is as high as 651°C, significantly higher than diesel (210°C) and gasoline (427°C), and even higher than hydrogen (500°C). To achieve auto-ignition of ammonia fuel in a compression-ignition engine, the compression ratio must be increased to above 35 to raise the temperature within combustion chamber 8 above 651°C. In some embodiments, the required compression ratio of the engine can be lowered by adding a small amount of pilot fuel to the ammonia fuel to lower the auto-ignition temperature of the mixed fuel (ammonia fuel and pilot fuel). The pilot fuel can be hydrogen, diesel, methanol, or other fuels. For example, an ammonia-hydrogen mixture 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 fits tightly against the upper end surface of the cylinder liner 2, forming the top boundary of the combustion chamber 8. The combustion chamber 8 provides space for the combustion of the ammonia fuel. Furthermore, the pre-combustion chamber provides combustion space for the pilot fuel. One side of the shell 6 fits tightly against the side of the cylinder head 7. The shell 6 partially penetrates the cylinder head 7 and is embedded in the combustion chamber 8. The shell 6 portion located inside the combustion chamber 8 forms an injection surface. The injection surface is configured as an arc-shaped curved surface whose normal direction coincides with the center line of the shell 6. The pre-combustion chamber in the shell 6 is connected to the combustion chamber 8 via a first jet hole array 9, a second jet hole array 10, and a third jet hole array 11 provided on the injection surface. The combustion products of the pilot fuel can be divided into multiple jets (i.e., multiple combustion jets are formed) and injected into different areas of the combustion chamber 8 respectively.

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

[0043] like Figure 2 As shown, the combustion jets generated in the pre-combustion chamber are divided into multiple beams and respectively ejected 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 figure schematically shows the concentration distribution of ammonia fuel in the combustion chamber according to an embodiment of the present disclosure. Figure 4 The diagram schematically shows 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 presented via a color gradient, with darker areas (e.g., purple) indicating lower concentrations (close to 0), and lighter areas (e.g., yellow) indicating higher concentrations (up to 0.3, dimensionless), reflecting the uneven distribution of concentration within the combustion chamber. As shown in Figure 4, the color gradient from blue to red shows that the turbulent kinetic energy is low in blue areas (e.g., 2 m² / s²) and high in red areas (e.g., 30 m² / s²), indicating regional differences in turbulent kinetic energy. Therefore, the concentration and turbulent kinetic energy of ammonia fuel vary across different regions within the combustion chamber 8. The ignition conditions for ammonia fuel (e.g., local fuel concentration, temperature, and turbulence intensity) are determined by both the concentration field and the turbulent kinetic energy field. For example, regions with high turbulent kinetic energy accompanied by higher ammonia fuel concentrations can optimize mixing and promote a more complete combustion reaction.

[0046] Furthermore, by setting the first jet hole 91 in the first jet hole array 9 toward the upper part of the combustion chamber 8, the second jet hole 101 in the second jet hole array 10 toward the center of the combustion chamber 8, and the third jet hole 111 in the third jet hole array 11 toward the bottom of the combustion chamber 8, a specific distribution of multiple combustion jets is achieved, and corresponding combustion jets can be injected to achieve matching ignition conditions. For example, in the central area of ​​the combustion chamber 8, the ammonia fuel concentration is relatively high and it also exhibits the characteristics of high turbulent kinetic energy. This indicates that the amount of ammonia fuel in the central area of ​​the combustion chamber 8 is large and the mixing and heat transfer efficiency are high. By setting the second jet hole 101 in the second jet hole array 10 toward the center of the combustion chamber 8, this part of the combustion jet can use turbulence to quickly diffuse the combustion wave after injection, and it is easy to achieve global ignition; in the upper part of the 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 toward the upper part of the combustion chamber 8, this part of the combustion jet can also use turbulence to quickly ignite after injection. At the same time, the use of the combustion jet can be reduced accordingly to reduce the waste of ignition fuel; at the bottom of the combustion chamber 8, the ammonia fuel concentration is not high and the turbulent kinetic energy is low, so it is necessary to distribute sufficient combustion jets by setting the third jet hole 111 in the third jet hole array 11 toward the bottom of the combustion chamber 8.

[0047] In such an embodiment, by arranging the first jet hole array 9, the second jet hole array 10 and the third jet hole array 11 from top to bottom on the shell 6 of the pre-combustion mechanism, multiple combustion jets can be sprayed to ignite the ammonia fuel, so that the ammonia fuel burns simultaneously in multiple places in the combustion chamber 8, effectively reducing the negative impact of the difficulty of compression ignition of the ammonia fuel, the slow propagation speed of the combustion flame and the long combustion duration on the engine efficiency; due to the uneven distribution of the concentration and turbulent kinetic energy of the ammonia fuel in the combustion chamber 8, by arranging the first jet hole 91 toward the top of the combustion chamber 8, the second jet hole 101 toward the center of the combustion chamber 8, and the third jet hole 111 toward the bottom of the combustion chamber 8, corresponding combustion jets can be sprayed toward different areas in the combustion chamber 8, so that ammonia fuels of different concentrations and turbulent kinetic energy reach matching ignition conditions, effectively improving the ignition efficiency and promoting the stable ignition of the ammonia fuel, and also improving 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, and an output end of the first injector 5 is located in the pre-combustion chamber.

[0049] Furthermore, the first injector 5 is in the shape of a slender column as a whole, and one end of the first injector 5 is vertically mounted on the side wall of the shell 6 exposed to the cylinder head 7 (that is, the outer side wall opposite to the part of the shell 6 embedded in the cylinder head 7), and the output end of the first injector 5 passes through the side wall and is connected to the interior of the pre-combustion chamber to spray the ignition fuel into the pre-combustion chamber, and the output end of the first injector 5 is facing the central area inside the pre-combustion chamber, so that the sprayed ignition fuel can be evenly diffused radially to the pre-combustion chamber space (that is, with the output end of the first injector 5 as the center, it is radially distributed to the surrounding areas).

[0050] Specifically, in some embodiments, in the pre-combustion chamber, the pilot fuel is fully mixed with the air to form a combustible mixture. For pilot fuels suitable for compression ignition, such as diesel, after the combustible mixture is formed, the combustible mixture is strongly compressed by the pre-combustion chamber during the compression stroke, causing the temperature and pressure of the combustible mixture to rise sharply. When the auto-ignition temperature of the pilot fuel is reached, the pilot fuel burns rapidly in the pre-combustion chamber. Since the space of the pre-combustion chamber is relatively small, the combustion process can reach higher temperatures and pressures in a shorter time. The heat generated by the 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 by the combustion in the pre-combustion chamber are sprayed into the combustion chamber 8 in the form of high-speed jets through the first jet hole array 9, the second jet hole array 10, and the third jet hole array 11. After the combustion jet enters the combustion chamber 8, the ignition fuel it carries forms a mixed fuel with the ammonia fuel. Since the combustion jet has strong energy and activity, it can form multiple ignition sources in the combustion chamber 8 and accelerate the ignition speed of the mixed fuel in the combustion chamber 8, thereby helping to quickly achieve combustion of the ammonia fuel.

[0051] In such an embodiment, the pre-combustion chamber triggers the combustion of the combustion chamber 8 by first burning the ignition fuel in a smaller space to generate a combustion jet, thereby creating favorable conditions for combustion in the combustion chamber 8. Through the propagation and ignition of the combustion jet, the ignition environment in the combustion chamber 8 can be improved, and the ignition and combustion of the ammonia fuel can be accelerated.

[0052] like Figure 1 As shown, according to an embodiment of the present 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 in the cylinder liner 2. The at least two ammonia injectors 3 are symmetrically disposed in the cylinder liner 2 and are located between the top dead center and the bottom dead center of the piston 4.

[0053] Specifically, the piston 4 is cylindrical and conforms to the inner wall of the cylinder liner 2. A piston ring groove is provided on the outer surface of the piston 4 to seal the combustion chamber 8 and reduce friction. The top of the piston 4 is designed to be shallowly concave or flat, and the axis of the piston 4 completely coincides with the axis of the cylinder liner 2. The piston 4 can perform reciprocating linear motion within the cylinder liner 2. The top dead center (TDC) occurs when the top surface of the piston 4 and the bottom surface of the cylinder head 7 (i.e., the top boundary of the combustion chamber 8) form a minimum compression space. The bottom dead center (BDC) occurs when the piston 4 descends to near the bottom of the cylinder liner 2.

[0054] Specifically, at least two ammonia injectors 3 are slender, tubular in shape and inject 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 a gas to be combusted. At least two ammonia injectors 3 are arranged circumferentially along the cylinder liner 2. Furthermore, when there are two ammonia injectors 3, they are symmetrically distributed along the diameter of the cylinder liner 2, with an included angle of 180°. This ensures that the ammonia fuel is injected from both sides of the combustion chamber 8, forming a counter-injection flow field. When there are three ammonia injectors 3, they are evenly distributed around the circumference of the cylinder liner 2 at 120° intervals. The ammonia fuel injected by the three ammonia injectors 3 diffuses radially within the combustion chamber 8. When four ammonia injectors 3 are used, they are evenly distributed along the circumference of the cylinder liner 2, with adjacent ammonia injectors 3 forming a 90° angle, forming a cross-shaped injection pattern, allowing the ammonia fuel to be injected into the combustion chamber 8 in a symmetrical jet pattern. In the vertical direction of the cylinder liner 2, at least two ammonia injectors 3 are located approximately 1 / 3-1 / 2 of the combustion chamber height below the top dead center of the piston 4, that is, near the upper middle area 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 the air to form a uniform gas to be burned. It also avoids the ammonia fuel being injected near the cylinder head 7 due to being too high, resulting in uneven local concentration, or being injected too early during the piston's downward movement due to being too low, resulting in poor mixing of the ammonia fuel and air. Specifically, after injection, the liquid ammonia fuel forms an atomizing cone with a cone angle of 30°-60°, and after injection, the gaseous ammonia fuel forms a fan-shaped diffusion flow, which couples with the vortex generated during the upward compression process of the piston 4 to promote uniform mixing of the ammonia fuel and air in the combustion chamber 8.

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

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

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

[0058] Specifically, the exhaust valve 1 is installed through a valve hole reserved in the top of the cylinder head 7, with the axis of the valve hole perpendicular to the upper surface of the cylinder head 7. The exhaust valve 1 is a disc-shaped structure made of a high-temperature resistant alloy, consisting of a valve disc and a valve stem. The valve disc has a smooth surface and a conical sealing surface on its edge. When the valve disc is inserted into the valve hole, this sealing surface tightly mates with the valve seat on the inner wall of the valve hole to achieve a seal. The valve stem is fixed vertically to the center of the valve disc and is slender and cylindrical, extending to the outside of the cylinder head 7, facilitating connection to 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 combustion process in the pre-combustion chamber is not disturbed during the exhaust process. At the same time, this position can ensure that the exhaust gas in the combustion chamber 8 is smoothly discharged through the exhaust valve 1 when the piston moves up to the exhaust stroke. Specifically, when the exhaust valve 1 is closed, the valve disc fits tightly against the valve seat to prevent leakage of high-temperature and high-pressure gas in the combustion chamber 8; when the exhaust valve 1 is opened, the valve disc is driven away from the valve seat by the upward movement of the valve stem, forming an annular exhaust channel to achieve efficient exhaust gas discharge. Among them, since the exhaust gas after the combustion of ammonia fuel 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 the piston 4 reaches the bottom dead center of the power stroke and moves upward, the exhaust valve 1 opens in a timely manner (or can open earlier at the end of the expansion stroke), utilizing the free exhaust phase, where the exhaust pressure in the combustion chamber 8 (higher than atmospheric pressure) is high, to rapidly expel most of the exhaust gas. Subsequently, during the forced exhaust phase, the piston 4 forces the remaining exhaust gas out of the combustion chamber 8. Specifically, after the combustion jet generated by the pre-combustion chamber triggers ignition in the combustion chamber 8, the exhaust gas in the combustion chamber 8 may contain incompletely reacted ammonia, intermediate products, and pollutants. Rapid opening of the exhaust valve 1 can reduce the residence time of the high-temperature exhaust gas in the combustion chamber 8 and inhibit the generation of pollutants. If localized unburned areas (such as areas with low ammonia fuel concentration) exist in the combustion chamber 8, the flow area and opening pattern of the exhaust valve 1 must ensure that the exhaust gas in these areas is effectively discharged to prevent 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 gases to be combusted, raising the pressure and temperature within combustion chamber 8 and creating conditions for the combustion jet to trigger ignition. Exhaust valve 1 can be closed later than top dead center of the exhaust stroke, utilizing the inertia of the exhaust flow to "draw" residual exhaust gases.

[0062] In such an embodiment, by opening / closing the exhaust valve 1 at the right time, it is possible to ensure that the exhaust gas is efficiently discharged and the combustion chamber 8 is well sealed, thereby providing a favorable environment for the combustion jet to trigger ignition.

[0063] like Figure 2-Figure 4 As shown, according to an embodiment of the present 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. Among them, 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 a portion of a hemispherical surface and employ three first jet holes 91. Specifically, the three first jet holes 91 are evenly spaced along the circumference of the injection surface, ensuring that multiple combustion jets can be injected into the combustion chamber 8 in a divergent yet symmetrical manner. The axes of the three first jet holes 91 are perpendicular to the tangent plane of the injection surface, ensuring that the combustion jets are injected into the upper portion of the combustion chamber 8 at high speed and in the most direct path. Furthermore, the three first jet holes 91 are all located in a spatial region 5-8 mm above the top dead center of the piston 4, preventing the combustion jets from directly impacting the top of the piston 4 and reducing the thermal load and mechanical stress on the piston 4.

[0065] In this embodiment, the arrangement of first jet holes 91 takes advantage of the relatively uniform concentration and turbulent kinetic energy distribution of the ammonia fuel in the upper region of the combustion chamber 8. The combustion jets ejected from the first jet hole array 9 are distributed in a fan-shaped pattern. The uniform aperture ensures consistent flow and velocity across each jet, allowing the combustion products of the pilot fuel to diffuse evenly within the combustion chamber 8 and improving the stability of the ammonia fuel combustion process in the upper region of the combustion chamber 8. Furthermore, when three first jet holes 91 are used to form three combustion jets, a stable triangular energy distribution pattern can be established within the combustion chamber 8, achieving efficient coverage of the upper region within the combustion chamber 8.

[0066] Furthermore, in some embodiments, if the ammonia fuel and air are not sufficiently mixed near the wall of the combustion chamber 8, a high momentum jet is required to destroy the stratification to promote mixing. At this time, the aperture of the first jet hole 91 at the corresponding position can be increased to increase the jet momentum to enhance the suction capacity of the ammonia fuel near the wall.

[0067] like Figures 1-4 As shown, according to the embodiment of the present disclosure, after the ammonia injector 3 injects ammonia fuel, the ammonia fuel diffuses as the piston 4 moves. During the diffusion process, the ammonia fuel is mainly concentrated in the central area of ​​the combustion chamber 8, resulting in a high concentration of ammonia fuel in this area and high turbulent kinetic energy. However, unlike the upper area of ​​the combustion chamber 8, the concentration and turbulent kinetic energy of the ammonia fuel in the central area of ​​the combustion chamber 8 show obvious uneven distribution characteristics. Therefore, based on this characteristic, it is necessary to further subdivide the second jet holes 101 in the second jet hole array 10. Specifically, as shown in FIG. Figure 2 As shown, the second jet hole 101 includes at least two side jet holes 1011 and at least one middle jet hole 1012. The side jet holes 1011 and the middle jet hole 1012 are arranged in a row array at equal intervals along the same height, and at least two side jet holes 1011 are arranged symmetrically with the middle jet hole 1012 as the center. Furthermore, since the concentration and turbulent kinetic energy of the ammonia fuel at the two sides of the central area in the combustion chamber 8 are similar, the apertures of at least some of the side jet holes 1011 are set to be the same. Further, as Figure 3 As shown, the concentration of ammonia fuel in the central area of ​​the combustion chamber 8 is lower on both sides than in the middle. Figure 4 As shown, the turbulent kinetic energy of the ammonia fuel in the central area of ​​the combustion chamber 8 is also lower on both sides than in the middle. Therefore, the aperture of the middle jet hole 1012 is set to be larger than the aperture of the jet holes 1011 on both sides. By further comparing the numerical value relationship of the concentration and turbulent kinetic energy in the upper area and the central area of ​​the combustion chamber 8, the aperture size relationship of the first jet hole 91 and the second jet hole 101 can be further set accordingly. For example, Figure 3As shown, the concentration value in the upper area of ​​the combustion chamber 8 is 1 / 3 to 1 / 2 of the concentration value at both sides of the central area. Based on this feature, the aperture of the first jet hole 91 can be set to 1 / 3 to 1 / 2 of the aperture of the jet holes 1011 on both sides.

[0068] Furthermore, in some embodiments, a middle jet hole 1012 may be provided at the center of the second jet hole array 10, and two side jet holes may be provided, with the axes of the middle jet hole 1012 and the side jet holes 1011 being perpendicular to the section of the injection surface.

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

[0070] In this embodiment, a combustion jet with a relatively large flow rate is allocated to the high concentration and high turbulent kinetic energy of the ammonia fuel in the central portion of the combustion chamber 8. This combustion jet carries more pilot fuel, thereby providing the central portion of the central portion of the combustion chamber 8 with stronger ignition energy, leading to rapid ignition and complete combustion. This improves ignition efficiency and avoids the problem of pilot fuel being wasted due to insufficient utilization of the pilot fuel at positions on both sides of the central portion of the combustion chamber 8. Furthermore, the flow rate relationship between the multiple combustion jets obtained in the upper and central portions of the combustion chamber 8 is further clarified. The allocation of the pilot fuel quantity takes into account the actual amount of ammonia fuel at different locations within the combustion chamber 8, resulting in a more uniform fuel mixture and a more stable combustion process in the upper and central portions of the combustion chamber 8.

[0071] like Figure 2-Figure 4 As shown, according to an embodiment of the present disclosure, since the concentration and turbulent kinetic energy distribution of the ammonia fuel at the bottom of the combustion chamber 8 are relatively uniform, the third jet hole array 11 includes at least two third jet holes 111, and the at least two third jet holes 111 are arranged in a row array at equal intervals along the same height, so that different positions at the bottom of the combustion chamber 8 can obtain combustion jets. Furthermore, the apertures of at least some of the third jet holes 111 are set to be the same, so that most positions in the bottom area of ​​the combustion chamber 8 can obtain combustion jets with consistent flow rates. Furthermore, since the amount of ammonia fuel distributed in the upper and bottom areas of the combustion chamber 8 is similar, the total injection flow rate of the third jet hole array 11 is set to be the same as the total injection flow rate of the first jet hole array 9. Furthermore, the aperture of the third jet hole 111 can be set to be larger than the aperture of the first jet hole 91, and the number of the third jet holes 111 can be set to be smaller than the number of the first jet holes 91.

[0072] Specifically, in some embodiments, during the engine combustion process, if the amount of ammonia fuel and pilot fuel in the upper and lower regions of the combustion chamber 8 differs significantly, such as intense combustion in the upper region and insufficient combustion in the lower region, a local high-temperature region may easily form at the cylinder head 7 or piston 4. The material of the cylinder head 7 or piston 4 may generate alternating thermal stresses due to inconsistent thermal expansion in the high-temperature region and the low-temperature region, which can easily cause fatigue cracks during long-term operation. Therefore, the total injection flow rate of the third jet hole array 11 must be the same as the total injection flow rate of the first jet hole array 9. Furthermore, when three first jet holes 91 are provided, the number of third jet holes 111 can be set to two so that the third jet holes 111 adopt a larger aperture, wherein the axes of the two third jet holes 111 are both perpendicular to the cross-section of the injection surface.

[0073] In this embodiment, on the one hand, the amount of pilot fuel received by the bottom region of the combustion chamber 8 is evenly distributed, improving the stability of the ammonia fuel combustion process in this region. Simultaneously, equal combustion in the upper and bottom regions of the combustion chamber 8 evenly distributes the thermal load on the cylinder head 7 or piston 4, preventing material fatigue caused by localized overheating and extending the engine's service life. Furthermore, 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 possesses greater momentum and a higher temperature. This increases the local temperature while entraining surrounding gases to be combusted, ensuring sufficient combustion at the bottom, reducing afterburning losses during the upward movement of the piston 4 and further improving thermal efficiency.

[0074] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be used in combination to advantage. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A non-uniform jet pre-combustion chamber injection system, characterized in that: include: A cylinder head (7) and a cylinder liner (2), wherein a combustion chamber (8) is defined between the cylinder head (7) and the cylinder liner (2); The pre-combustion mechanism is arranged on the cylinder head (7) and comprises: A shell (6), wherein a pre-combustion chamber is formed in the shell (6), and a first jet hole array (9), a second jet hole array (10), and a third jet hole array (11) are respectively provided on a side of the shell facing the combustion chamber (8) from top to bottom; 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).

2. The pre-combustion chamber injection system according to claim 1, characterized in that The pre-combustion mechanism further comprises a first injector (5), the output end of the first injector (5) being located in the pre-combustion chamber.

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

4. The system according to claim 1, wherein: The first jet hole array (9) comprises at least two first jet holes (91), and the at least two first jet holes (91) are arranged in a row array at equal intervals along the same height; Wherein, at least two of the first jet holes (91) in the first jet hole array (9) are configured to have the same aperture.

5. The system according to claim 4, characterized in that The second jet hole (101) comprises: At least two side jet holes (1011); at least one intermediate jet hole (1012); The two side jet holes (1011) and the middle jet hole (1012) are arranged in a row array at equal intervals along the same height, and at least two of the two side jet holes (1011) are symmetrically arranged with the middle jet hole (1012) as the center.

6. The system according to claim 5, characterized in that The apertures of at least some of the jet holes (1011) on both sides are set to be the same; The aperture of the middle jet hole (1012) is set to be larger than the apertures of the jet holes (1011) on both sides.

7. The system according to claim 6, characterized in that The aperture of the first jet hole (91) is set to 1 / 3 to 1 / 2 of the aperture of the jet holes (1011) on both sides.

8. The system according to claim 1, wherein: The third jet hole array (11) comprises at least two third jet holes (111), and the at least two third jet holes (111) are arranged in a row array at equal intervals along the same height; The apertures of at least some of the third jet holes (111) are set to be the same, and the total jet flow rate of the third jet hole array (11) is set to be the same as the total jet flow rate of the first jet hole array (9).

9. The system according to claim 8, characterized in that The aperture of the third jet hole (111) is set to be larger than the aperture of the first jet hole (91), and the number of the third jet holes (111) is set to be smaller than the number of the first jet holes (91).

10. The system according to claim 1, wherein: Also includes: An exhaust valve (1) is provided on the cylinder head (7).

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