CN110391592B

CN110391592B - Spark plug, engine, spark plug ignition method and engine ignition method

Info

Publication number: CN110391592B
Application number: CN201810368115.4A
Authority: CN
Inventors: 张东柯; 徐文强; 朱明明; 李先明; 张柘子; 孙琦; 万直剑; 王传付
Original assignee: China Energy Investment Corp Ltd; National Institute of Clean and Low Carbon Energy
Current assignee: China Energy Investment Corp Ltd; National Institute of Clean and Low Carbon Energy
Priority date: 2018-04-23
Filing date: 2018-04-23
Publication date: 2021-07-13
Anticipated expiration: 2038-04-23
Also published as: WO2019205908A1; CN110391592A

Abstract

The invention relates to the technical field of engine ignition, and discloses a spark plug, an engine, a spark plug ignition method and an engine ignition method. The spark plug comprises an outer shell, a discharge electrode and a grounding electrode, wherein a precombustion chamber with an opening is formed in the outer shell, the grounding electrode is arranged in the precombustion chamber, and the discharge electrode extends into the precombustion chamber and forms an ignition gap with the grounding electrode. After the spark plug is installed on a cylinder head of an engine, the pre-combustion chamber is communicated with a combustion chamber of the engine through the opening, so that after a fuel and air mixture enters the combustion chamber, part of the fuel and air mixture can enter the pre-combustion chamber through the opening.

Description

Spark plug, engine, spark plug ignition method and engine ignition method

Technical Field

The invention relates to the technical field of engine ignition, in particular to a spark plug, an engine, a spark plug ignition method and an engine ignition method.

Background

Currently, spark ignition engines are capable of extending into the combustion chamber of the engine via a spark plug to discharge and ignite a fuel-air mixture within the combustion chamber. The performance of the spark plug directly affects the performance of the engine.

Ammonia may be used as a fuel for spark-ignited internal combustion engines. The combustion of ammonia does not produce CO2, and reduces the influence of greenhouse gases on the environment. The ammonia can be synthesized by renewable energy sources, and the dependence of human on non-renewable fossil energy sources is reduced. On the other hand, engines that are now fueled by gases (e.g., natural gas, biogas, syngas, etc.) are typically supplied with lean fuel mixtures, i.e., air and fuel mixtures of high air-to-fuel ratios.

However, the ignition performance of ammonia gas is poor and the flame propagation speed is very low, and the conventional spark plug cannot effectively solve the problem that ammonia gas is not easy to catch fire and burn in the cylinder internal combustion engine. In addition, the lean mixture often results in poor ignition, deflagration, and incomplete combustion, and similarly, conventional spark plugs do not effectively ignite the lean mixture within the combustion chamber and the spark plugs have a very short life.

Disclosure of Invention

It is an object of the present invention to provide a spark plug that is effective in achieving efficient ignition and combustion of ammonia and other gaseous fuels in lean burn conditions.

In order to achieve the above object, the present invention provides a spark plug including a shell in which a pre-chamber having an opening is formed, a discharge electrode provided in the pre-chamber, and a ground electrode that protrudes into the pre-chamber and forms an ignition gap with the ground electrode.

According to the technical scheme, the pre-combustion chamber is formed in the shell of the spark plug, the ignition gap between the discharge electrode and the grounding electrode is located in the pre-combustion chamber, the pre-combustion chamber is provided with the opening, after the spark plug is installed on a cylinder cover of an engine, the pre-combustion chamber is communicated with the combustion chamber of the engine through the opening, so that after a fuel and air mixture enters the combustion chamber, part of the fuel and air mixture enters the pre-combustion chamber through the opening, due to the fact that the volume of the pre-combustion chamber is small, at the moment, an electric spark formed by discharge between the discharge electrode and the grounding electrode ignites the fuel, high-temperature and high-pressure combustion gas formed in the pre-combustion chamber enters the combustion chamber through the opening in a jet mode, and then the fuel in the combustion.

Further, the size of the ignition gap can be adjusted.

Still further, the ground electrode and/or the discharge electrode are configured to be adjustable to adjust the ignition gap.

Further, the ground electrode is provided in a telescopic structure.

In addition, the size of the ignition gap is 0.1-1 mm.

In addition, the ground electrode is connected to an inner circumferential surface of the precombustion chamber.

Further, the ground electrode is integrally formed with the housing.

In addition, the discharge electrode includes an electrode cylinder protruding into the pre-combustion chamber and a discharge tip formed on the electrode cylinder and located in the pre-combustion chamber, the discharge tip and the ground electrode forming the ignition gap therebetween.

Further, the discharge ends are plural and arranged on the electrode cylinder at intervals in the circumferential direction, and each discharge end corresponds to the respective ground electrode.

Further, at least one of the discharge tip and the ground electrode is a needle-like structure.

In addition, a combustion supporting catalyst layer is formed on a surface of at least one of the discharge electrode and the ground electrode.

Further, the combustion-supporting catalyst layer is a platinum, rhodium, gold, gong or tungsten-vanadium alloy layer.

In addition, the spark plug includes an insulator, wherein the insulator is provided within the shell such that a part of the shell inner space is formed as the pre-combustion chamber, and the discharge electrode protrudes into the pre-combustion chamber through the insulator.

Additionally, the spark plug includes an end cap having a plurality of mesh openings, the end cap being disposed over the opening.

Further, the size of the mesh can be adjusted.

Further, the end caps comprise two stacked layers, one layer of the end cap being capable of lateral movement relative to the other side cap to adjust the size of the overlapping area of the cells.

Further, the end cover is a metal mesh or a porous plate.

Further, the apertures of the meshes are set to be larger than the minimum extinction gap of the flame of the ignited fuel entering into the pre-chamber.

Further, the end cover is installed on the opening through a fixing cover with an opening, wherein internal threads on the side wall of the fixing cover are matched with external threads of the shell, external threads are formed on the outer peripheral surface of the side wall of the fixing cover, and the opening is formed in the bottom wall of the fixing cover and the end cover is pressed and installed.

In addition, the volume of the precombustion chamber is set to be less than 1% of the cylinder displacement of the engine in which the spark plug is installed.

The present invention also provides an engine comprising a spark plug as described in any of the above, in addition to any spark plug as described in any of the above, wherein the spark plug may be mounted at any suitable location of the engine, such as on a cylinder head, wherein the pre-chamber communicates with a cylinder combustion chamber of the engine via the opening. Thus, as described above, the ignition performance and overall quality of the engine are significantly improved.

Further, based on the inventive concept for solving the problems, the present invention provides a spark plug ignition method in which a pre-chamber having an opening is formed in a shell of a spark plug and an ignition electrode of the spark plug such as a discharge electrode and a ground electrode is provided in the pre-chamber, the spark plug ignition method comprising: the electric spark generated by the discharge of the ignition electrode in the precombustion chamber firstly ignites the fuel entering the precombustion chamber, and the combustion gas formed in the precombustion chamber can be jetted and flowed out from the opening.

Therefore, after the mixture of the fuel and the air enters the combustion chamber, part of the mixture enters the pre-combustion chamber through the opening, the volume of the pre-combustion chamber inside the ignition plug is small due to the limit of the structure of the ignition plug, at the moment, the electric spark formed by the discharge between the ignition electrode such as the discharge electrode and the grounding electrode ignites the fuel in the pre-combustion chamber, the high-temperature and high-pressure combustion gas formed in the pre-combustion chamber enters the combustion chamber through the opening jet flow, and then the fuel in the combustion chamber is ignited, so that the stable and efficient ignition and combustion are realized.

Further, a combustion-supporting catalyst layer is arranged on the outer surface of the ignition electrode.

Finally, the present invention provides an engine ignition method comprising the spark plug ignition method as described in any of the above, wherein the combustion gas formed in the pre-chamber of the spark plug is jetted out from the opening into the combustion chamber of the engine and ignites the fuel in the combustion chamber. As described above, according to the engine ignition method, stable and efficient ignition and combustion of the engine can be achieved.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic diagram of an exemplary spark plug configuration according to an embodiment of the present invention;

fig. 2 is a schematic diagram of an exemplary configuration of the discharge and ground electrode distribution in the spark plug of fig. 1.

Description of the reference numerals

1-shell, 2-discharge electrode, 3-ground electrode, 4-opening, 5-precombustion chamber, 6-ignition gap, 7-electrode cylinder, 8-discharge end, 9-insulator, 10-end cover and 11-fixing cover.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

Referring to the structure shown in fig. 1, the spark plug provided by the present invention comprises a shell 1, a discharge electrode 2 and a ground electrode 3, wherein a precombustion chamber 5 having an opening 4 is formed in the shell 1, the ground electrode 3 is disposed in the precombustion chamber 5, and the discharge electrode 2 penetrates through the wall of the precombustion chamber 5 to project into the precombustion chamber 5 and form an ignition gap 6 with the ground electrode 3.

In this technical solution, since the housing 1 of the spark plug is formed with the pre-chamber 5, and the ignition gap 6 between the discharge electrode 2 and the ground electrode 3 is located in the pre-chamber 5, and the pre-chamber 5 has the opening 4, after the spark plug is mounted on the cylinder head of the engine, the pre-chamber 5 will be communicated with the combustion chamber of the engine through the opening 4, so that after the fuel and air mixture enters the combustion chamber, part of the mixture will enter the pre-chamber 5 through the opening 4, because the volume of the pre-chamber 5 is small, even if the fuel adopts ammonia gas or lean fuel mixture, the electric spark formed by the discharge between the discharge electrode 2 and the ground electrode 3 can ignite the fuel in the pre-chamber 5, the high temperature and high pressure combustion gas formed in the pre-chamber 5 enters the combustion chamber through the opening 4 jet flow, and then the fuel in the combustion chamber is ignited, thereby realizing stable and efficient ignition and combustion, therefore, the spark plug can effectively realize high-efficiency stable and reliable ignition and stable and reliable combustion under the lean-burn working condition of ammonia gas and other gas fuels, improves the ignition efficiency, and is particularly suitable for the gas fuels with low heat value, low flame propagation speed and high ignition energy.

In addition, the size of the ignition gap 6 formed between the discharge electrode 2 and the ground electrode 3 also affects the generation of an electric spark and thus the ignition effect, and therefore, in order to be applicable to different fuels, it is preferable that the size of the ignition gap 6 be adjustable as shown in fig. 1, for example, in the structure shown in fig. 1, the size of the ignition gap 6 be radially adjustable, or, when the discharge electrode 2 and the ground electrode 3 are disposed along the axial direction of the housing, the size of the ignition gap 6 be axially adjustable depending on the positional relationship of the discharge electrode 2 and the ground electrode 3.

Of course, adjustment of the size of the ignition gap 6 may be achieved in a variety of ways, such as, for example, in one way, by adjusting the position of the ground electrode 3 relative to the discharge electrode 2 (as indicated by the arrow in fig. 2), or, in another way, by adjusting the position of the discharge electrode 2 relative to the ground electrode 3, or, in yet another way, by adjusting both the ground electrode 3 and the discharge electrode 2 to adjust the ignition gap 6. That is, before the spark plug is mounted to the engine, the ignition gap 6 is adjusted accordingly according to the fuel required by the engine.

Further, the adjustment of the ground electrode 3 and/or the discharge electrode 2 may be achieved in various ways, for example, in one way, the ground electrode 3 and/or the discharge electrode 2 may be provided as a telescopic structure in the form of a plurality of conductive joints which are sequentially sleeved, so that the ground electrode 3 and/or the discharge electrode 2 can be telescopic to adjust the length; alternatively, in another mode, the ground electrode 3 and/or the discharge electrode 2 may be formed as a telescopic structure in the form of a flexible conductive wire extending in a reciprocating bending manner, and the length of the flexible conductive wire is changed by stretching or compressing, which also enables adjustment of the ignition gap 6.

In addition, the ignition gap 6 may be in any suitable range as long as it is sufficient for the spark generation after the energization, for example, the size of the ignition gap 6 may be 0.1 to 1mm, preferably 0.5 mm.

Of course, the ground electrode 3 may be provided in the precombustion chamber 5 in various ways, such as in one form, and in the structure shown in fig. 1, the ground electrode 3 may be attached to the inner peripheral surface of the precombustion chamber 5 so that the ignition gap 6 in the radial direction will be formed between the ground electrode 3 and the discharge electrode 2. Alternatively, in another form, the ground electrode 3 may be disposed on the end cap 10 such that when the discharge end of the discharge electrode 2 extends axially, an ignition gap 6 is formed between the ground electrode 3 and the discharge electrode 2 in the axial direction, and when the discharge end of the discharge electrode 2 extends radially, an ignition gap 6 is formed between the ground electrode 3 and the discharge electrode 2 in the radial direction.

Of course, the ground electrode 3 may be bonded, welded or snapped to the housing by screws, conductive paste, or, in order to improve the reliability of the connection, it is preferable that the ground electrode 3 is integrally formed with the housing, that is, the connection end of the ground electrode 3 is integrally formed with the housing.

Alternatively, the discharge electrode 2 may have various forms, such as a conductive wire, or, as shown in fig. 1, the discharge electrode 2 includes an electrode cylinder 7 extending into the precombustion chamber 5 and a discharge tip 8 formed on the electrode cylinder 7 and located in the precombustion chamber 5, with the ignition gap 6 formed between the discharge tip 8 and the ground electrode 3. In this way, the electrode cylinder 7 can significantly improve the reliability of the positioning of the discharge electrode 2 while being conductive.

Further, in order to enlarge the generated spark and improve the ignition effect, it is preferable that, as shown in fig. 1 and 2, the discharge tips 8 are plural and arranged on the electrode cylinder 7 at intervals in the circumferential direction, and each discharge tip 8 corresponds to the respective ground electrode 3, for example, in fig. 2, there are three sets of the discharge tips 8 and the ground electrodes 3 corresponding to each other in the radial direction, so that a substantially annular spark is formed and the mixed fuel in the pre-combustion chamber is more easily ignited. Of course, in practical use, the number of the ground electrodes and the discharge ends may be increased or decreased.

In addition, as shown in fig. 2, at least one of the discharge end 8 and the ground electrode 3 has a needle-like structure. In this way, it is possible to achieve stable ignition at a lower spark voltage, reducing the energy required for ignition to facilitate the formation of the ignition center at a low ignition voltage.

In addition, in order to further enhance the ignition effect, it is preferable that a combustion supporting catalyst layer is formed on a surface of at least one of the discharge electrode 2 and the ground electrode 3. For example, a combustion-supporting catalyst layer is formed on the surfaces of the discharge end 8 and the ground electrode 3 having a needle-like structure, and the combustion-supporting catalyst layer can increase the oxidation rate of the fuel, release heat, and promote ignition. Thus, under the dual actions of the combustion-supporting catalyst layer and the precombustion chamber, the electric spark generated between the discharge end 8 and the grounding electrode 3 is easier to ignite the fuel in the precombustion chamber, and the catalytic combustion function is realized.

Further, the combustion-supporting catalyst layer may be a platinum, rhodium, gold, tungsten, or tungsten-vanadium alloy layer, and may be deposited on the surfaces of the discharge end 8 and the ground electrode 3 by chemical deposition or electrochemical deposition.

In addition, in order to enhance the reliability of the positioning of the discharge electrode 2 and the insulation from the shell, as shown in fig. 1, the spark plug includes an insulator 9 such as ceramic, wherein the insulator 9 is provided inside the shell 1 such that a part of the inner space of the shell 1 is formed as the pre-combustion chamber 5, and the discharge electrode 2 protrudes into the pre-combustion chamber 5 through the insulator 9. Thus, the insulator can effectively insulate the discharge electrode 2 from the shell while maintaining good mechanical strength of the spark plug in a high-temperature environment.

In addition, in order to enhance the protection of the discharge tip 8 and the ground electrode 3, it is preferable that, as shown in fig. 1, the spark plug includes an end cover 10 having a plurality of meshes, and the end cover 10 is provided on the opening 4, so that, in the structure shown in fig. 1, the shell, the insulator, and the end cover 10 form a pre-combustion chamber in which combustion gas can enter into the combustion chamber through the meshes on the end cover 10.

Further, in order to adapt to different fuels and combustion conditions, it is preferable that the size of the mesh be adjustable so that an appropriately matched mesh can be selected according to different fuels and combustion conditions. Of course, mesh sizing may be accomplished in a variety of ways, such as, for example, in one manner, a plurality of end caps 10 having different pore sizes may be provided, such that the respective end caps 10 may be selectively replaced. Or alternatively, the end cap 10 may be provided with an adjusting plate having corresponding openings, and the size of the mesh may be adjusted by moving the adjusting plate to adjust the size of the overlapping area between the openings of the adjusting plate and the mesh. Alternatively, in yet another form, the end cap 10 comprises two stacked layers, one layer being laterally movable relative to the other side end cap to adjust the size of the overlapping region of the cells, which can also adjust the size of the cells.

Further, the end cap 10 is a metal mesh or a perforated plate, and of course, the mesh on the metal mesh and the holes on the perforated plate will form a mesh.

In addition, in order to further facilitate the entry of the combustion gas in the precombustion chamber into the combustion chamber through the mesh on the end cover 10, it is preferable that the aperture of the mesh is set to be larger than the minimum extinction gap of the flame of the ignited fuel entering the precombustion chamber 5, so that the combustion gas in the precombustion chamber does not extinguish when passing through the mesh as long as this condition is satisfied, and the fuel in the combustion chamber can be ignited stably and reliably.

Of course, the end cap 10 may be mounted on the opening 4 in various ways, for example, by means of a screw or the like, or by means of a snap structure, or in order to facilitate the mounting of the spark plug, preferably, as shown in fig. 1, the end cap 10 is mounted on the opening 4 by means of a fixing cap 11 having an opening, wherein an internal thread on a side wall of the fixing cap 11 is fitted with an external thread of the housing 1, an external thread is formed on an outer circumferential surface of the side wall of the fixing cap 11, and an opening is formed on a bottom wall of the fixing cap 11 and the end cap 10 is press-fitted. Thus, the end cap 10 is mounted on the opening 4 by a screw-fit between the fixing cap 11 and the housing, while the external screw thread on the fixing cap 11 also facilitates the attachment of the spark plug to the cylinder head.

Finally, the volume of the prechamber 5 can be chosen according to the actual requirements, but, in order to improve the ignition effect, it is preferred that the volume of the prechamber 5 is arranged to be less than 1% of the cylinder displacement of the engine in which the spark plug is installed. In this way, the small amount of gas that enters the prechamber 5 is more easily ignited.

The present invention provides, in addition to any of the spark plugs described above, an engine including a spark plug as described above, wherein the pre-chamber communicates with a cylinder combustion chamber of the engine through an opening, for example, the spark plug may be provided on a cylinder head of the engine such that the pre-chamber may be located within the cylinder combustion chamber and communicate with the cylinder combustion chamber through the opening. Thus, as described above, in one embodiment, during operation, when the engine piston moves upward during a compression cycle, air and fuel enter the prechamber through the mesh openings in the end cover, a small amount of fuel-air mixture ignites and combusts in the prechamber, and the resulting high-temperature, high-pressure combustion products enter the cylinder combustion chamber through the mesh openings and ignite the fuel-air mixture in the cylinder combustion chamber, thereby achieving efficient and stable ignition and combustion. In this way, the ignition performance and the overall quality of the engine are significantly improved.

Further, the present invention provides a spark plug ignition method, based on the same concept of solving the problems of the prior art, of forming a pre-chamber having an opening in a housing of a spark plug and disposing an ignition electrode of the spark plug in the pre-chamber, the spark plug ignition method comprising: the electric spark generated by the discharge of the ignition electrode in the precombustion chamber firstly ignites the fuel entering the precombustion chamber, and the combustion gas formed in the precombustion chamber can be jetted and flowed out from the opening.

Further, in order to further enhance the ignition effect, a combustion-supporting catalyst layer is provided on an outer surface of at least one of the ignition electrode such as the discharge electrode and the ground electrode. The combustion-supporting catalyst layer can improve the oxidation rate of the fuel, release heat and promote ignition. Thus, under the dual actions of the combustion-supporting catalyst layer and the precombustion chamber, the electric spark generated between the discharge tail end of the discharge electrode and the grounding electrode can easily ignite the fuel in the precombustion chamber, and the catalytic combustion function is realized.

Further, the combustion-supporting catalyst layer may be a platinum, rhodium, gold, tungsten, or tungsten-vanadium alloy layer, and may be deposited on the surfaces of the discharge end and the ground electrode by a chemical deposition method or an electrochemical deposition method.

Further, in the spark plug ignition method, at least one of the discharge tip and the ground electrode of the ignition electrode such as the discharge electrode is in a needle-like structure. In this way, it is possible to achieve stable ignition at a lower spark voltage, reducing the energy required for ignition to facilitate the formation of the ignition center at a low ignition voltage.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A spark plug, characterized by comprising an outer shell (1), a discharge electrode (2) and a ground electrode (3), wherein a pre-chamber (5) having an opening (4) is formed in the outer shell (1), the ground electrode (3) is disposed in the pre-chamber (5), and the discharge electrode (2) protrudes into the pre-chamber (5) and forms an ignition gap (6) with the ground electrode (3);

the discharge electrode (2) comprises an electrode cylinder (7) extending into the pre-combustion chamber (5) and a discharge tip (8) formed on the electrode cylinder (7) and located within the pre-combustion chamber (5), the discharge tip (8) and the ground electrode (3) forming the ignition gap (6) therebetween;

the discharge ends (8) are multiple and are arranged on the electrode cylinder (7) at intervals along the circumferential direction, and each discharge end (8) corresponds to the grounding electrode (3);

the volume of the precombustion chamber (5) is set to be less than 1% of the cylinder displacement of the engine in which the spark plug is installed.

2. The spark plug as claimed in claim 1, characterized in that the size of the ignition gap (6) is adjustable.

3. The spark plug as claimed in claim 2, characterized in that the ground electrode (3) and/or the discharge electrode are arranged to be adjustable for adjusting the ignition gap (6).

4. A spark plug according to claim 3, wherein the ground electrode (3) is provided in a telescopic configuration.

5. The spark plug according to claim 2, wherein the size of the ignition gap (6) is 0.1-1 mm.

6. The spark plug according to claim 1, wherein the ground electrode (3) is attached to an inner peripheral surface of the precombustion chamber (5).

7. The spark plug of claim 6 wherein said ground electrode (3) is integrally formed with said shell.

8. The spark plug according to claim 1, wherein at least one of the discharge tip (8) and the ground electrode (3) is of a needle-like structure.

9. The spark plug according to any one of claims 1 to 8, wherein a combustion-supporting catalyst layer is formed on a surface of at least one of the discharge electrode (2) and the ground electrode (3).

10. The spark plug of claim 9 wherein said combustion supporting catalyst layer is a platinum, rhodium, gold, gong or tungsten vanadium alloy layer.

11. A spark plug according to claim 1, characterized in that the spark plug comprises an insulator (9), wherein the insulator (9) is arranged inside the outer shell (1) such that a part of the inner space of the outer shell (1) forms the pre-chamber (5), the discharge electrode (2) protruding through the insulator (9) into the pre-chamber (5).

12. The spark plug of claim 1, including an end cap (10) having a plurality of mesh openings, the end cap (10) being disposed over the opening (4).

13. The spark plug of claim 12 wherein said mesh is adjustable in size.

14. The spark plug of claim 13 wherein said end cap (10) includes two stacked layers, one layer being laterally movable relative to the other side end cap to adjust the overlap area size of the cells.

15. The spark plug of claim 12 wherein said end cap (10) is a metal mesh or a porous plate.

16. Spark plug according to claim 12, characterized in that the apertures of the meshes are arranged to be larger than the minimum extinction gap for the flame of the ignited fuel entering the pre-chamber (5).

17. The spark plug according to claim 12, wherein the end cap (10) is mounted on the opening (4) through a fixing cap (11) having an opening, wherein an internal thread on a side wall of the fixing cap (11) is fitted with an external thread of the housing (1), an external thread is formed on an outer peripheral surface of a side wall of the fixing cap (11), and a bottom wall of the fixing cap (11) is formed with the opening and press-fitted with the end cap (10).

18. An engine, characterized in that it is provided with a spark plug according to any one of claims 1-17, wherein the prechamber (5) communicates with the cylinder combustion chamber of the engine through the opening (4).

19. A spark plug ignition method characterized by forming a pre-chamber having an opening in a housing of a spark plug and disposing an ignition electrode of the spark plug in the pre-chamber, the spark plug ignition method comprising: the electric spark generated by the discharge of the ignition electrode in the precombustion chamber firstly ignites the fuel entering the precombustion chamber, and the combustion gas formed in the precombustion chamber can be jetted and flowed out from the opening.

20. The method of claim 19, wherein a combustion supporting catalyst layer is disposed on an outer surface of the firing electrode.

21. An engine ignition method, characterized in that it comprises the ignition method of a spark plug according to claim 19 or 20, wherein combustion gas formed in the pre-chamber of the spark plug is jetted out from the opening into the combustion chamber of the engine and ignites fuel in the combustion chamber.