A pre-combustion chamber spark plug and a marine ammonia-hydrogen mixed fuel engine

Abstract

This invention discloses a pre-combustion chamber spark plug and a marine ammonia-hydrogen mixed fuel engine. The pre-combustion chamber spark plug includes a pre-combustion chamber and a spark plug. The spark plug, from the outside to the inside, includes a shell, an insulator, a center electrode, and a side electrode. The cavity formed by the lower end of the shell and the inner wall of the pre-combustion chamber shell serves as the pre-combustion chamber. The lower part of the pre-combustion chamber shell is provided with a lower spray hole and multiple side wall spray holes. The lower spray hole is located at the extension line of the end of the center electrode and penetrates the main combustion chamber and the pre-combustion chamber. The side wall spray holes are staggered around the lower spray hole and are used to inject water and hydrogen fuel into the pre-combustion chamber. The marine ammonia-hydrogen mixed fuel engine includes a pre-combustion chamber spark plug. The side wall spray holes first inject hydrogen fuel into the pre-combustion chamber and then inject water. The flame in the pre-combustion chamber vaporizes and decomposes the injected water and hydrogen fuel to form a jet flame containing active free radicals, which is injected into the main combustion chamber. The ammonia fuel injected into the cylinder is ignited by the jet flame containing active free radicals.

Description

Technical Field

[0001] This invention belongs to the field of generator pre-combustion chambers, specifically relating to a pre-combustion chamber spark plug and a hydrogen-ammonia mixed fuel engine suitable for ships. Background Technology

[0002] With energy and environmental issues becoming increasingly severe, research and industrialization of alternative fuel technologies to address existing or potential environmental problems and achieve energy diversification have become imperative. Ammonia, as a hydrogen-rich compound, has many advantages: high energy density, no carbon content, produces water and nitrogen gas upon complete reaction, does not generate pollutants or the greenhouse gas carbon dioxide, is easy to store and transport, has a sound industrial base, and is relatively inexpensive in the market.

[0003] In today's world, international trade is developing rapidly, with more than 80% of transportation being carried out by sea.

[0004] As a relatively versatile technology, the pre-combustion chamber has received widespread attention in engine research and application. Its principle involves creating a small cavity (i.e., the pre-combustion chamber) in the engine connected to the main combustion chamber via one or more holes. Active air distribution can be achieved within the pre-combustion chamber by arranging a fuel supply device, or air exchange can rely solely on the engine's own cycle. Ignition can be achieved by placing the spark plug electrodes within the pre-combustion chamber. Optimizing the pre-combustion chamber spark plug is a key technology. The pre-combustion chamber spark plug is similar to a conventional spark plug, except that its electrodes are located within the pre-combustion chamber and can communicate with the main combustion chamber through a nozzle at the end of the pre-combustion chamber. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and propose a pre-combustion chamber spark plug with a pre-combustion chamber structure and a hydrogen-ammonia mixed fuel engine suitable for ships. In addition to having a lower spray hole that communicates with the main combustion chamber, the pre-combustion chamber also has side wall spray holes for spraying water and hydrogen fuel into the pre-combustion chamber. The side wall spray holes can spray water and hydrogen fuel into the pre-combustion chamber, whereby the high temperature and high pressure environment can vaporize and decompose water to form highly active free radicals (hydroxyl groups OH, H, O, etc.) to help improve the combustion characteristics of ammonia fuel.

[0006] The first aspect of this invention is to provide a pre-combustion chamber spark plug, comprising a pre-combustion chamber and a spark plug, wherein the spark plug comprises, from the outside to the inside, a housing, an insulator, a center electrode and a side electrode; the housing has threads on at least a portion of its outer wall for fixing to the cylinder head;

[0007] The insulator is a tubular structure, arranged along the central axis of the pre-combustion chamber spark plug, with one end fixedly connected to the housing and the other end extending into the pre-combustion chamber; a central electrode is fixedly arranged in the hollow area of ​​the insulator, and the end of the central electrode extends into the pre-combustion chamber, with the ends of the insulator and the central electrode extending 8-12mm beyond the bottom of the housing; the central axis of the central electrode is coaxial with the pre-combustion chamber spark plug.

[0008] The side electrode is located in the pre-combustion chamber, with one end fixed to the bottom of the housing and the other end facing the end of the center electrode; a spark plug gap is formed between the center electrode and the side electrode, and the end of the side electrode away from the housing is 4-7 mm away from the bottom of the pre-combustion chamber;

[0009] The bottom of the housing is fixed to the top of a pre-combustion chamber housing, and the cavity formed by the lower end of the housing and the inner wall of the pre-combustion chamber housing serves as the pre-combustion chamber. The lower part of the pre-combustion chamber housing is provided with a lower spray hole and multiple side wall spray holes. The lower spray hole is located at the extension line of the end of the central electrode and passes through the main combustion chamber and the pre-combustion chamber. The side wall spray holes are arranged alternately around the lower spray hole. The side wall spray holes are connected to pipelines for injecting hydrogen fuel and hydrogen-containing oxides or peroxides into the pre-combustion chamber. The volume of the pre-combustion chamber cavity does not exceed 5% of the volume of the main combustion chamber.

[0010] Furthermore, the hydrogen-containing oxide or peroxide injected into the pre-combustion chamber is selected from substances containing H or OH free radicals or capable of generating high energy, such as water, hydrogen peroxide, and sodium peroxide.

[0011] Furthermore, the sidewall nozzles are evenly distributed around the central axis of the spark plug, and the axial direction of the sidewall nozzles is at a 45-90 degree angle to the axial direction of the housing.

[0012] The second aspect of this invention is to provide a marine ammonia-hydrogen mixed fuel engine, comprising a cylinder head, a cylinder liner, a main combustion chamber, and a piston. The top of the cylinder head is provided with an intake valve, an exhaust valve, a fuel injector, and a spark plug in the pre-combustion chamber. The fuel injector nozzle extends into the intake manifold to inject a portion of ammonia fuel into the intake manifold, while the remaining ammonia fuel is directly injected into the cylinder. The engine cylinder head, cylinder liner, and piston together form the main combustion chamber.

[0013] The pre-combustion chamber spark plug is vertically installed inside the cylinder head and located directly above the main combustion chamber. The central axis of the central electrode is coaxial with the pre-combustion chamber spark plug. Hydrogen-containing oxides or peroxides and hydrogen fuel are introduced into the pre-combustion chamber.

[0014] When the piston is at top dead center, the side wall nozzle first injects hydrogen fuel into the pre-combustion chamber, and then injects hydrogen-containing oxides or peroxides into the pre-combustion chamber from the side wall nozzle; the amount of hydrogen-containing oxides or peroxides injected and the amount of hydrogen fuel are determined according to the hydrogen blending ratio selected by the user.

[0015] When the molar mass fraction of H radicals generated by hydrogen-containing oxides or peroxides and mixed hydrogen fuel in the cylinder reaches 10... -6 -10 -8 When the engine is in the range of its rated speed, intake air temperature, and fuel injection quantity, the engine's ECU determines the engine's real-time operating condition and instructs the spark plug to ignite. The flame in the pre-combustion chamber causes the injected hydrogen-containing oxides or peroxides and hydrogen fuel to vaporize and decompose, forming a jet flame containing active free radicals that is injected into the main combustion chamber. At the same time, the fuel injector injects ammonia fuel into the cylinder, which is ignited by the jet flame containing active free radicals generated by the spark plug in the pre-combustion chamber.

[0016] Furthermore, the pre-combustion chamber spark plug is located between the intake valve and the exhaust valve, and the angles between the intake and exhaust valves and the central axis of the main combustion chamber are unequal valve cone angles, with the exhaust valve cone angle being greater than the intake valve cone angle.

[0017] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0018] The pre-combustion chamber spark plug described in this invention is used to ignite the pre-combustion chamber. The flame in the pre-combustion chamber causes the water and hydrogen fuel injected through the side wall nozzles to vaporize and decompose into a jet flame containing active free radicals. The jet flame enters the main combustion chamber and mixes with ammonia fuel for combustion, which is beneficial to the stable combustion of ammonia-hydrogen fuel. Compared with traditional marine engines, it has higher thermal efficiency.

[0019] The central shafts of the spark plugs and center electrodes in the main combustion chamber and pre-combustion chamber, as well as the lower injection orifice, are all coaxially arranged to ensure that the fuel injected into the lower injection orifice is precisely positioned at the top dead center of the main combustion chamber, which is beneficial to achieving optimal fuel combustion. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the pre-combustion chamber spark plug and the overall combustion device described in this invention;

[0021] Figure 2 This is a cross-sectional view of the marine ammonia-hydrogen mixed fuel engine described in this invention;

[0022] Figure 3 This is a cross-sectional view of the pre-combustion chamber spark plug according to the present invention;

[0023] Figure 4 This is a bottom view of the pre-combustion chamber shell.

[0024] In the picture:

[0025] 3: Main combustion chamber 4: Casing 5: Insulator 6: Central electrode 7: Side electrode 8: Pre-combustion chamber shell 9: Lower spray hole 11: Cylinder head 12: Cylinder Liner 13: Piston 21: Spark plugs 22: Pre-combustion chamber 23: Side wall spray holes 31: Air intake 32: Exhaust passage 33: Intake valve 34: Exhaust valve 35: Injector Detailed Implementation

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments described are only for explanation and illustration of the present invention and are not intended to limit the present invention.

[0027] like Figure 1-2 As shown, a marine ammonia-hydrogen mixed fuel engine includes a cylinder head 11, a cylinder liner 12, a main combustion chamber 3, and a piston 13. The top of the cylinder head 11 is provided with an intake manifold 31, an exhaust manifold 32, an intake valve 33, an exhaust valve 34, a fuel injector 35, and a pre-combustion chamber spark plug. The injector nozzle of the fuel injector 35 extends into the intake manifold 31 to inject a portion of the ammonia fuel into the intake manifold; the remaining ammonia fuel is directly injected into the cylinder. The ends of the intake manifold 31, exhaust manifold 32, intake valve 33, exhaust valve 34, and pre-combustion chamber spark plug all extend into the main combustion chamber. The cylinder liner 12 is also provided with mounting holes for a portion of the exhaust manifold 32 and exhaust valve guide (not shown in the figure). The engine cylinder head 11, cylinder liner 12, and piston 13 together form the main combustion chamber 3.

[0028] The pre-combustion chamber spark plug is vertically mounted inside the cylinder head 11 and partially extends into the main combustion chamber 3, located directly above the main combustion chamber. Its top is connected to the ignition coil. The pre-combustion chamber spark plug is positioned between the intake and exhaust valves, and the angles between the intake and exhaust valves and the central axis of the main combustion chamber (since the pre-combustion chamber spark plug is directly above the main combustion chamber, its central axis is coaxial with the central axis of the main combustion chamber) are unequal valve cone angles, with the exhaust valve cone angle being larger than the intake valve cone angle. Since a smaller cone angle results in better sealing performance, and a larger cone angle results in a larger opening, a larger exhaust valve cone angle is beneficial for exhaust, while a smaller intake valve cone angle facilitates direct air entry into the combustion chamber. Figure 3 As shown, the pre-combustion chamber 22 and the spark plug 21 constitute the main body of the pre-combustion chamber spark plug. The spark plug 21 includes, from the outside to the inside, a housing 4, an insulator 5, a center electrode 6, and a side electrode 7. The housing 4 is a tubular structure made of metal, and its upper half has threads on its outer wall for fixed connection to the cylinder head 11. A hemispherical pre-combustion chamber housing 8 is fixedly connected to the bottom of the housing 4. The outer contour of the bottom of the housing 4 matches the top contour of the pre-combustion chamber housing 8, thereby forming a closed structure. The cavity formed by the inner wall of the pre-combustion chamber housing 8 and the lower end of the housing 4 serves as the pre-combustion chamber 22. The lower part of the pre-combustion chamber housing 8 extends into the main combustion chamber 3, and the volume of the pre-combustion chamber 22 does not exceed 40% of the volume of the main combustion chamber.

[0029] One end of the insulator 5 is fixedly connected to the housing 4 and is arranged along the central axis of the spark plug in the pre-combustion chamber. A central electrode 6 is fixedly arranged in the hollow area inside the insulator 5. Both the ends of the insulator 5 and the central electrode 6 extend into the pre-combustion chamber 22, with the end of the central electrode extending 10 mm beyond the bottom of the housing. A side electrode 7 is located inside the pre-combustion chamber 22, with one end fixed to the bottom of the housing 4 and the other end facing the end of the central electrode 6. A spark plug gap is formed between the central electrode 6 and the side electrode 7, which is located inside the pre-combustion chamber 22 and has a spacing of 0.8 mm. The end of the side electrode away from the housing 4 is 5 mm away from the bottom of the pre-combustion chamber.

[0030] like Figure 4 As shown, the bottom of the pre-combustion chamber shell 8, facing the main combustion chamber, has a lower spray hole 9 and four side wall spray holes 23. The lower spray hole 9 is located at the extension line of the end of the central electrode 6. The side wall spray holes 23 are evenly distributed in a circle around the central axis of the spark plug 21, and the axial direction of the side wall spray holes 23 is at an angle of 45-90 degrees to the axial direction of the shell. The lower spray hole penetrates the main combustion chamber 3 and the pre-combustion chamber 22, while the side wall spray holes 23 do not penetrate the main combustion chamber 3. The side wall spray holes 23 are connected to pipelines for injecting water and hydrogen fuel into the pre-combustion chamber 22. The partial flame ignited in the pre-combustion chamber generates a high-temperature and high-pressure environment, allowing sufficient time for the injected water and hydrogen fuel to undergo the water vaporization process, thereby decomposing the water into highly reactive free radicals (hydroxyl groups OH, H, O, etc.) to help improve the combustion characteristics of ammonia fuel. The parameters of the sidewall nozzles and the lower nozzles can be adjusted according to the combustion characteristics of different engines, such as position, number, and size, to change the combustion time characteristics and obtain the best combustion and emission results.

[0031] The central axis of the central electrode is coaxial with the pre-combustion chamber spark plug, which in turn is coaxial with the cylinder liner. This ensures that when the pre-combustion chamber spark plug is in use, the fuel injected from the lower injection hole 9 can be precisely positioned near the top dead center of the main combustion chamber. Viewed from the central axis of the spark plug, four sidewall injection holes 23 are arranged around the lower injection hole 9, and these holes 23 are staggered. This arrangement has the advantage that when the spark plug ignites, a flame is generated in the pre-combustion chamber. The flame is released through the lower injection hole 9 to the vicinity of the top dead center of the main combustion chamber 3. The water and hydrogen fuel injected into the pre-combustion chamber through the sidewall injection holes 23 can form highly reactive free radicals, improving the combustion characteristics of ammonia fuel, increasing the turbulence intensity of the in-cylinder mixture, and resulting in more complete combustion. Furthermore, the staggered arrangement of the sidewall injection holes 23 can reduce interference and overlap between adjacent fuel streams.

[0032] The working principle of the ship's ammonia-hydrogen mixed fuel engine is as follows:

[0033] Knowing the rated power and speed of the engine under 100% load, the work done by a single cylinder can be calculated. The work done by the ammonia-hydrogen mixed fuel combustion engine described in this invention can be calculated using the formula: "Work = Ammonia fuel quantity * Ammonia calorific value + Hydrogen fuel quantity * Hydrogen calorific value". The formula for the hydrogen blending ratio is: Hydrogen fuel quantity * Hydrogen calorific value / (Hydrogen fuel quantity * Hydrogen calorific value + Ammonia fuel quantity * Ammonia calorific value).

[0034] When the piston is at top dead center (the injection timing can also be changed according to the actual situation), the side wall injection hole first injects hydrogen fuel into the pre-combustion chamber. The amount of hydrogen fuel injected is determined by the user selecting the hydrogen blending ratio according to the above formula. The error between the work done by the engine described in this invention and the work done by the original engine does not exceed the allowable value.

[0035] The amount of water injected into the pre-combustion chamber from the side wall nozzles is determined according to different operating conditions. The amount of water injected is determined by the hydrogen doping ratio selected by the user, but the amount of water should not be too much, otherwise it will cause cooling and be bad for the combustion process.

[0036] The molar mass fraction of H radicals generated by water spraying in the cylinder is approximately on the order of 10. -6 -10 -8 The engine ECU determines the engine's operating condition based on the engine speed, intake air temperature, and fuel injection quantity. It then determines whether spark plug 21 is needed for ignition based on the real-time operating conditions. If spark plug 21 is needed, an ignition instruction is immediately issued. The flame in the pre-combustion chamber 22 vaporizes and decomposes the injected water and hydrogen fuel to form a jet flame containing active free radicals, which is then injected into the main combustion chamber 3. At the same time, the fuel injector 35 injects ammonia fuel into the cylinder, which is ignited by the jet flame containing active free radicals generated by the spark plug 21 in the pre-combustion chamber.

[0037] Although preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these are within the scope of protection of the present invention.

Claims

1. A marine ammonia-hydrogen mixed fuel engine, comprising a cylinder head (11), a cylinder liner (12), a main combustion chamber (3), and a piston (13), wherein the top of the cylinder head (11) is provided with an intake valve (33), an exhaust valve (34), and a fuel injector (35), characterized in that, It also includes a pre-combustion chamber spark plug; the injector (35) has its nozzle inserted into the intake manifold (32) to inject part of the ammonia fuel into the intake manifold, and the remaining ammonia fuel is injected directly into the cylinder; the engine cylinder head (11), cylinder liner (12) and piston (13) together form the main combustion chamber (3). The pre-combustion chamber spark plug includes a pre-combustion chamber (22) and a spark plug (21). The spark plug (21) includes a housing (4), an insulator (5), a center electrode (6), and a side electrode (7) from the outside to the inside. The bottom of the housing (4) is fixed to the top of a pre-combustion chamber housing (8). The lower part of the pre-combustion chamber housing (8) is provided with a lower spray hole (9) and multiple side wall spray holes (23). The pre-combustion chamber spark plug is vertically installed inside the cylinder head (11) and located directly above the main combustion chamber (3). The central axis of the central electrode (6) is coaxial with the pre-combustion chamber spark plug. Hydrogen fuel and hydrogen-containing oxides or peroxides are introduced into the pre-combustion chamber (22). When the piston is at top dead center, the side wall nozzle (23) first injects hydrogen fuel into the pre-combustion chamber (22). The amount of hydrogen fuel injected is determined according to the hydrogen blending ratio calculated by the following formula: Hydrogen fuel quantity * hydrogen calorific value / (hydrogen fuel quantity * hydrogen calorific value + ammonia fuel quantity * ammonia calorific value); Furthermore, the error between the work done by the engine and the work done by the original engine does not exceed the allowable value; Then, hydrogen-containing oxides or peroxides are injected into the pre-combustion chamber (22) through the side wall injection hole (23); the amount of hydrogen-containing oxides or peroxides injected and the amount of hydrogen fuel are determined according to the hydrogen blending ratio selected by the user. When the molar mass fraction of H radicals generated by hydrogen-containing oxides or peroxides and mixed hydrogen fuel in the cylinder reaches 10... -6 -10 -8 When the engine is in the range, the ECU determines the engine's operating condition based on the engine speed, intake air temperature, and fuel injection quantity. The spark plug (21) is ignited, and the flame in the pre-combustion chamber (22) causes the injected hydrogen-containing oxides or peroxides and hydrogen fuel to vaporize and decompose, forming a jet flame containing active free radicals that is injected into the main combustion chamber (3). At the same time, the fuel injector (35) injects ammonia fuel into the cylinder, which is ignited by the jet flame containing active free radicals generated by the spark plug (21) in the pre-combustion chamber. Moreover, the pre-combustion chamber spark plug is located between the intake valve (33) and the exhaust valve (34), and the angles between the intake and exhaust valves and the central axis of the main combustion chamber (3) are unequal valve cone angles, with the exhaust valve cone angle being greater than the intake valve cone angle.

2. The marine ammonia-hydrogen mixed fuel engine according to claim 1, characterized in that, The insulator (5) of the pre-combustion chamber spark plug is a tubular structure, arranged along the central axis of the pre-combustion chamber spark plug, with one end fixedly connected to the housing (4) and the other end extending into the pre-combustion chamber (22); a central electrode 6 is fixedly arranged in the hollow area of ​​the insulator (5), and the end of the central electrode extends into the pre-combustion chamber (22). The ends of the insulator (5) and the central electrode (6) extend beyond the bottom of the housing (4) by 8-12 mm; the central axis of the central electrode (6) is coaxially arranged with the pre-combustion chamber spark plug. The side electrode (7) is located inside the pre-combustion chamber (22), with one end fixed to the bottom of the housing (4) and the other end facing the end of the center electrode (6); a spark plug gap is formed between the center electrode (6) and the side electrode (7), and the end of the side electrode away from the housing (4) is 4-7 mm away from the bottom of the pre-combustion chamber (22); The housing (4) has threads on at least part of its outer wall for fixing to the cylinder head (11); The cavity formed by the lower end of the housing (4) and the inner wall of the pre-combustion chamber housing (8) serves as the pre-combustion chamber (22); the lower spray hole (9) is located at the extension line of the end of the central electrode (6) and passes through the main combustion chamber (3) and the pre-combustion chamber (22); the side wall spray holes (23) are staggered around the lower spray hole (9), and the side wall spray holes (23) are connected to pipelines for injecting hydrogen fuel and hydrogen-containing oxides or peroxides into the pre-combustion chamber (22); and the volume of the pre-combustion chamber (22) does not exceed 5% of the volume of the main combustion chamber.

3. The pre-combustion chamber spark plug according to claim 1, characterized in that, The sidewall nozzles (23) are evenly distributed around the central axis of the spark plug (21), and the axial direction of the sidewall nozzles (23) is at a 45-90 degree angle to the axial direction of the housing (4).

4. The pre-combustion chamber spark plug according to claim 1, characterized in that, The hydrogen-containing oxides or peroxides injected into the pre-combustion chamber are selected from water, hydrogen peroxide, and sodium peroxide.

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