Spark plug

Abstract

A spark plug, comprising: an insulator (1); a central electrode (3); a metal housing (2); and a side electrode (4). A front end portion (41) of the side electrode (4) is provided with an opening portion (411), and projection is performed in the axis direction AL of the central electrode (3), such that a projection surface S2 of an ignition end surface (31) of the central electrode (3) on a perpendicular plane Z to the axis of the central electrode (3) completely falls within a projection surface S1 of the opening portion (411) on the perpendicular plane Z to the axis of the central electrode (3), such that the ignition end surface (31) of the central electrode (3) is not shielded. Moreover, the front end portion (41) of the side electrode (4) is divided into two small end portions by the opening portion (411), and an ignition end of the central electrode (3) is thin, such that oil (5) is not easily attached to the ignition end surface (31) of the central electrode (3) and an opening of the side electrode (4), thereby rapidly raising the temperature of the side electrode (4) while enhancing the capability of resisting oil droplet accumulation in a spark gap of the spark plug, and improving the ignition performance of the spark plug. The width of the side electrode (4) ensures the heat dissipation capability and service life of the spark plug.

Description

A spark plug TECHNICAL FIELD

[0001] The present application relates to a spark plug, in particular to a spark plug assembled in an internal combustion engine for igniting an air-fuel mixture. BACKGROUND

[0002] With the continuous progress of engine technology, especially the continuous popularization and application of high compression ratio, high EGR rate, supercharged direct injection, lean burn and other technologies, the engine has higher and higher requirements for the ignition quality of the spark plug. The spark plug is an important electrical device in the ignition system of a gasoline engine. The spark plug is used to ignite the compressed gasoline mixture in the cylinder, so that the engine starts to work. With the in-depth development of new energy vehicles, hybrid power has become the mainstream. When the hybrid engine is used at low temperature, especially in winter, the engine frequently starts and stops at low temperature. Because the fuel atomization is poor under low temperature working condition, fuel droplets are easily attached to the surface of each part of the combustion chamber, especially when the engine fails to start for the first time. The oil droplets sprayed will be attached to the surface of the center electrode and the side electrode of the spark plug. At this time, a large amount of oil droplets is easily deposited at the spark plug jump fire gap, causing the jump fire gap to accumulate oil droplets and fail (as shown in FIGS. 1 and 2), thereby affecting the ignition between the center electrode and the side electrode, and reducing the ignition performance of the spark plug.

[0003] Through retrieval, the patents related to the present application mainly include the following patents:

[0004] For example, the patent with the authorization announcement number CN2512137Y and the authorization announcement date of September 18, 2002 relates to a spark plug for gasoline and gas engine ignition, and specifically relates to a tooth side electrode spark plug, which comprises a center electrode and a tooth side electrode. The tooth side electrode has a tooth tip at the upper end, and the lower end of the tooth side electrode is welded with the shell to achieve electrical communication. The tooth tip is higher than the end surface of the center electrode and does not cover the end surface of the center electrode. There is a certain gap between the axial projection of the tooth side electrode and the cylindrical surface of the center electrode. The tooth side electrode is single or uniformly distributed in two. The tooth side electrode and the outer edge of the center electrode end form a sharp angle, which promotes the complete combustion of the mixture, reduces pollution, achieves reliable ignition, rapid start, fuel saving and power increase, and the effect is more obvious for the use of gas engine.

[0005] However, the area of the front end of the side electrode in the above-mentioned document is still large, so that more oil will be attached to the side electrode, thereby affecting the ignition. At the same time, the distance between the front end of the side electrode and the outer edge of the center electrode ignition end away from the rear end of the side electrode is far, which requires higher pulse ignition voltage, thereby causing poor spark plug ignition.

[0006] Therefore, how to design a spark plug which can reduce the oil attached to the side electrode and shorten the distance between the front end of the side electrode and the outer edge of the center electrode ignition end on the side away from the rear end of the side electrode, thereby greatly enhancing the oil-drop accumulation resistance of the spark gap is a technical problem to be solved. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a spark plug with an open portion of a side electrode which can reduce the oil attached to the side electrode and shorten the distance between the front end of the side electrode and the outer edge of the center electrode ignition end on the side away from the rear end of the side electrode, thereby greatly enhancing the oil-drop accumulation resistance of the spark gap.

[0008] To solve the above technical problem, the technical solution adopted by the present application is as follows: a spark plug, comprising a rod-shaped center electrode extending along an axial direction AL; an insulator having an axial hole extending along the axial direction and retaining the center electrode in the axial hole, the center electrode being arranged on the front end side of the insulator; a metal shell surrounding and retaining the insulator in the circumferential direction, the rear end of the insulator extending out of the metal shell along the axial direction; and a side electrode, the front end of the side electrode being arranged in the horizontal direction, the rear end of the side electrode being arranged along the center electrode axial direction AL, the rear end of the side electrode being welded to the front end surface of the metal shell, and the front end of the side electrode being provided with an open portion, the center electrode axial line being set as line P, the vertical plane of the center electrode axial line P being set as Z plane, and the ignition end surface of the center electrode being set as Z1 plane; the open portion of the side electrode is projected on the Z plane along the center electrode axial direction AL, the projection plane of the open portion of the side electrode on the Z plane being set as S1 plane, and the projection plane of the center electrode ignition end surface Z1 plane on the Z plane being set as S2 plane; and S2 plane is completely within S1 plane.

[0009] Further, the center line of the front end of the side electrode is set as L in the horizontal direction, the center line L is consistent with the opening direction of the open portion of the side electrode, the perpendicular line passing through the bottom of the open portion of the side electrode is set as M, and the perpendicular line passing through the top of the open portion of the side electrode is set as N; the front end of the side electrode is projected on the Z plane along the center electrode axial direction AL, the projection plane of the front end of the side electrode on the Z plane being set as S plane; the corresponding projection lines of the perpendicular line M and the perpendicular line N on the Z plane are set as M' and N' along the center electrode axial direction AL;

[0010] the area of S plane between the projection line M' and the projection line N' is set as A1, the area of the projection plane S1 between the projection line M' and the projection line N' is set as A2, and the relationship between A1 and A2 is 0.06≤A2 / (A1+A2)≤0.4.

[0011] Further, a radius of the Z1 plane is set as R, and the R satisfies: 0.2mm≤R≤0.8mm.

[0012] Further, the opening part is V-shaped, U-shaped, frustum-shaped, cube-shaped, cuboid-shaped, etc.

[0013] Further, an angle of the V-shaped opening part is set as θ, and the angle θ satisfies: 10°≤θ≤80°.

[0014] Further, a projection of the center line L on the Z plane in the direction of the center electrode axis AL is set as L', two tangent lines M1 and N1 of the S2 plane are drawn, the line M1 and the line N1 are both perpendicular to the projection line L', and the line M1 is close to the opening bottom side.

[0015] An area of the S plane between the tangent line M1 and the tangent line N1 is set as B1, an area of the S1 plane between the tangent line M1 and the tangent line N1 is set as B2, and a relationship between B1 and B2 is: 0.1≤B2 / B1≤2.

[0016] Further, a width of the side electrode is set as D, and the D satisfies: 2mm≤D≤3.2mm.

[0017] Further, a distance between the line N' and the line N1 is set as C, and the C satisfies: 0mm≤C≤0.8mm.

[0018] The beneficial effects of the present application are that: the present application is provided with an opening part at the front end of the side electrode, and the projection of the center electrode ignition end face Z1 on the vertical plane Z of the center electrode axis is completely within the projection S1 of the opening part on the vertical plane Z of the center electrode axis, so that the center electrode ignition end face is not blocked, and the opening part forms two sharp end parts at the front end of the side electrode, which can minimize the oil attached to the side electrode and shorten the distance between the front end of the side electrode and the outer edge of the center electrode ignition end part away from the rear end of the side electrode, thereby greatly enhancing the oil droplet accumulation resistance of the spark plug jumping gap; the ignition end of the center electrode is thin and the radius of the center electrode ignition end face is further limited, so that the oil is less likely to adhere to the center electrode ignition end face and the sharp end part of the opening of the side electrode, thereby solving the oil accumulation problem between the two electrodes of the spark plug, greatly enhancing the oil droplet accumulation resistance of the spark plug jumping gap, improving the ignition performance of the spark plug, and further enabling the fuel to burn more fully, and the fuel is less likely to adhere between the electrodes, thereby greatly improving the anti-carbon accumulation ability of the spark plug; by further limiting the angle of the opening part of the side electrode, the ignition performance of the spark plug is good and the electrodes can quickly heat up at low temperature; by setting the width of the side electrode, the side electrode can quickly dissipate heat at high temperature, thereby ensuring the service life of the spark plug; and the ignition performance of the spark plug is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a schematic view of the axial cross-sectional structure of the prior art spark plug;

[0020] Figure 2 is a schematic view of the enlarged structure of part A in Figure 1;

[0021] Figure 3 is a schematic view of the axial cross-sectional structure of the spark plug in the embodiment of the present application;

[0022] Figure 4 is a schematic view of the front view structure of the spark plug in the embodiment of the present application;

[0023] Figure 5 is a schematic view of the three-dimensional structure of the spark plug in the embodiment of the present application when it is inclined at an angle;

[0024] Figure 6 is a schematic view of the enlarged structure of part B in Figure 5;

[0025] Figure 7 is a schematic view of the three-dimensional structure of the side electrode in the embodiment of the present application, which shows the positional relationship between the two parallel lines of the top end of the opening part and the bottom of the opening part and the center line of the side electrode;

[0026] Figure 8 is a schematic view of the corresponding positions of the projection of the front end of the side electrode and its opening part and the center electrode ignition end face on the vertical plane of the center electrode axis in the embodiment of the present application;

[0027] Fig. 9 is a plan view of the projection of the front end of Fig. 5 on a vertical plane along the axis of the center electrode, in the spark plug according to the embodiment of the present application;

[0028] Fig. 10 is a plan view of the characteristic plane of the front end of the side electrode, in the spark plug according to the embodiment of the present application;

[0029] Fig. 11 is a plan view of two tangent lines of the circle of Fig. 8;

[0030] Fig. 12 is a plan view of the projection of the side electrode and the projection of the opening portion forming a closed area, in the spark plug according to the embodiment of the present application.

[0031] In the drawings: 1. insulator, 2. metal shell, 3. center electrode, 31. firing end face, 4. side electrode, 41. front end, 411. opening portion, 5. oil. DETAILED DESCRIPTION

[0032] To make the objects, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described below in conjunction with Figs. 3-12 of the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art belong to the scope of protection of the present application.

[0033] It should be noted that all directional indications (such as up, down, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship of the components and the like in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0034] In addition, the shape described in the present application can be a cuboid, a square, a V shape, a U shape, a polygon, and other irregular shapes, all of which belong to the scope of protection of the present application.

[0035] Embodiment:

[0036] As shown in Fig. 3, a spark plug includes a rod-shaped center electrode 3 extending along an axial direction AL; an insulator 1 having an axial hole extending along the axial direction and retaining the center electrode 3 in the axial hole, the center electrode 3 being arranged at the front end side of the insulator 1 (the direction of the arrow AL in the drawing is the front end); a metal shell 2 circumferentially surrounding and retaining the insulator 1, the rear end of the insulator 1 extending out of the metal shell 2 along the axial direction; and a side electrode 4, the front end of the side electrode 4 being arranged in a horizontal direction, the rear end of the side electrode 4 being arranged along the axial direction AL of the center electrode 3, the rear end of the side electrode 4 being welded to the front end face of the metal shell 2.

[0037] As shown in Fig. 5 and Fig. 6, an opening part 411 is arranged at the front end part 41 of the side electrode 4. As shown in Fig. 4 and Fig. 6, the axis of the center electrode 3 is set as line P, the plane perpendicular to the axis P of the center electrode 3 is set as Z plane, and the ignition end surface 31 of the center electrode 3 is set as Z1 plane. When the projection is made along the axial direction AL of the center electrode 3, the projection plane of the opening part 411 of the side electrode 4 on the Z plane is set as S1 plane, and the projection plane of the ignition end surface 31 of the center electrode 3 on the Z plane is set as S2 plane. As shown in Fig. 8, the S2 plane is completely within the S1 plane. In this way, since the ignition end surface 31 of the center electrode 3 is not completely blocked by the side electrode 4, the remaining area of the front end part 41 of the side electrode 4 except the opening part 411 is further reduced, thereby further reducing the oil 5 adhered to the side electrode 4. In addition, the front end part 41 of the side electrode 4 is closer to the ignition end surface 31 of the center electrode 3, and the distance between the front end of the side electrode 4 and the outer edge of the ignition end part of the center electrode 3 away from the rear end part of the side electrode 4 is shortened, thereby shortening the jump gap and improving the ignition performance.

[0038] As shown in Fig. 7 and Fig. 9, the center line of the front end part 41 of the side electrode 4 is set as L in the horizontal direction, the center line L is consistent with the opening direction of the opening part 411 of the front end part 41 of the side electrode 4, the perpendicular line perpendicular to the center line L and passing through the bottom of the opening part 411 of the side electrode 4 is set as M, and the perpendicular line perpendicular to the center line L and passing through the top of the opening part 411 of the side electrode 4 is set as N. When the projection is made along the axial direction AL of the center electrode 3, the projection plane of the front end part 41 of the side electrode 4 on the Z plane is set as S plane. When the perpendicular line M and the perpendicular line N are projected along the axial direction AL of the center electrode 3, the corresponding projection lines of the perpendicular line M and the perpendicular line N on the Z plane are set as M' and N'. The area of the S plane between the projection line M' and the projection line N' is set as A1, and the area of the projection plane S1 between the projection line M' and the projection line N' is set as A2.

[0039] In order to better determine the influence of the opening part 411 of the front end of the side electrode 4 on the performance of the side electrode 4, the following will take a number of spark plugs and divide them into 9 groups, each group of the opening part 411 of the front end of the side electrode 4 corresponds to a specific size of the opening, then the area A2 of the opening part 411 of the front end of the side electrode 4 projected on the projection line M' and the projection line N' along the axis of the center electrode 3 and the area A1 of the side electrode 4 projected on the projection line M' and the projection line N' along the axis direction AL of the center electrode 3 correspond to 9 groups of different ratios of A2 and (A1+A2), under the same conditions, the heat capacity of the front end of the side electrode 4 of the 9 groups of spark plugs (i.e. the ability of the side electrode to quickly heat up at low temperature), the anti-overheating ability of the front end of the side electrode 4 (i.e. the ability of the side electrode to resist high temperature and dissipate heat), and the anti-oil immersion ability of the side electrode 4 (the ability to resist oil from adhering and accumulating on the side electrode) are tested, and the test results are shown in the following figure (where "●" represents excellent, " represents good, " represents medium, " represents qualified, and "○" represents poor):

[0040] From the above test results, it can be seen that as the A2 / (A1+A2) ratio increases, the heat capacity and the anti-oil immersion ability of the end of the side electrode 4 gradually change from poor to excellent, while the anti-overheating ability of the front end of the side electrode 4 is just the opposite; while increasing the anti-oil accumulation ability of the side electrode 4, the volume of the front end of the side electrode 4 will not affect the high temperature resistance and heat dissipation performance of the side electrode 4, so the area ratio range of A2 / (A1+A2) is preferably 0.06-0.4.

[0041] In addition, the ignition end of the center electrode 3 of the prior art spark plug is generally thick, and when the engine starts, the oil 5 sprayed is easy to adhere to the center electrode due to the greater tension on the relatively flat surface, and when the oil 5 sprayed covers the ignition end of the center electrode 3, it will still affect the anti-oil accumulation performance of the spark plug at the spark gap, and affect the ignition performance of the spark plug. Therefore, as shown in FIG. 10, the applicant also improves the ignition end surface 31 of the center electrode 3, that is, the radius R of the ignition end surface 31 of the center electrode 3 is set to different values: the area of the ignition end surface 31 of the center electrode 3 is reduced so that the ignition end surface 31 of the center electrode 3 is not easy to adhere to oil.

[0042] Through experiments, it can be determined (the data in the specific test process is not shown) that when the range of R is 0.2mm-0.8mm, the ignition end of the center electrode 3 is relatively thin, the ignition end of the center electrode 3 is not easy to adhere to the oil 5, and the spark plug is easy to ignite when R is in this range, and when R is preferably 0.20mm, 0.25mm, 0.30mm, 0.35mm, 0.4mm, the ignition effect of the spark plug is better.

[0043] The opening part 411 of the front end part 41 of the side electrode 4 can be V-shaped, U-shaped, frustum-shaped, cube-shaped, or cuboid-shaped, but in order to more clearly show the technical solutions, the opening part is preferably V-shaped (as shown in FIG. 7) in an embodiment.

[0044] As shown in FIG. 10, the angle θ of the V-shaped opening part 411. Through exploration of the angle θ of the V-shaped opening part 411, if the angle θ is too large, the front end part 41 of the side electrode 4 will be too small in volume, so that the heat dissipation capacity of the side electrode 4 is reduced, affecting the service life of the side electrode 4; if the angle is too small, the side electrode 4 will block the ignition end surface 31 of the center electrode 3, and oil is easy to accumulate in the spark plug gap, thereby affecting the ignition performance; when the angle θ is 10°-80°, the service life of the spark plug and the oil resistance of the front end of the side electrode 4 are ensured.

[0045] As shown in FIGS. 11 and 12, projection is made along the axis direction AL of the center electrode 3, the projection line of the center line L on the Z plane is set as L', two tangent lines M1 and N1 of the S2 surface are drawn, the line M1 and the line N1 are both perpendicular to the projection line L', and the line M1 is close to the opening bottom side; the area of the S surface between the tangent line M1 and the tangent line N1 is set as B1, and the area of the S1 surface between the tangent line M1 and the tangent line N1 is set as B2.

[0046] In order to further determine the influence of the opening part 411 of the front end of the side electrode 4 on the oil resistance at the spark plug gap, the service life of the side electrode 4, and the ignition performance of the spark plug, the side electrode of the above-mentioned 9 groups of spark plugs is further limited, and the applicant carries out tests on the oil resistance at the spark plug gap, the service life of the side electrode 4, and the ignition performance of the spark plug for the 9 groups of spark plugs with different B2 / B1 ratios. The test results are shown in the following figure (wherein “●” represents excellent, “◇” represents good, “△” represents medium, “◇” represents qualified, and “○” represents poor):

[0047] It can be known from the above test results that: with the continuous increase of the B2 / B1 ratio, the oil immersion resistance at the spark plug gap gradually changes from poor to excellent, the service life of the side electrode 4 gradually changes from excellent to poor, and the ignition performance of the spark plug first changes from poor to excellent and then changes from excellent to poor; this shows that the larger the opening part 411 of the front end of the side electrode 4 is, the less likely the front end part 41 of the side electrode 4 is to accumulate oil, but the larger the opening is, the smaller the volume of the front end part 41 of the side electrode 4 is, the worse the heat dissipation and high-temperature resistance are, and the more likely the side electrode 4 is to be damaged, thereby affecting the service life and ignition performance of the spark plug.

[0048] Through the test results, the B2 / B1 range is preferably 0.1-2, the side electrode 4 increases the ability to resist oil droplet accumulation while also ensuring the performance of the side electrode 4 in resisting high temperatures and dissipating heat, thereby ensuring the ignition performance and service life of the side electrode 4.

[0049] The rear end of the side electrode 4 is welded to the metal shell 2 of the spark plug, and the heat dissipation of the side electrode 4 of the spark plug is achieved by transferring heat from the rear end of the side electrode 4 to the metal shell 2, so the width D (as shown in FIG. 10) of the side electrode 4 directly affects the ability of the side electrode 4 to dissipate heat, thereby affecting the service life of the side electrode of the spark plug, but if the width D of the side electrode 4 is too wide, it will increase the production cost, and through experiments and comparisons, when the width of the side electrode 4 of the spark plug is in the range of 2mm-3.2mm, the side electrode 4 with the opening portion 411 has good heat dissipation capacity, which ensures the service life of the side electrode 4 of the spark plug.

[0050] As shown in FIGS. 7, 9, and 11, a perpendicular line N is set that is perpendicular to the center line L of the front end 41 of the side electrode 4 and passes through the top of the opening portion 411 of the side electrode 4, the corresponding projection line N' of the perpendicular line N on the Z plane, a straight line N that is perpendicular to the projection line L' and tangent to the S plane, when the distance C between the line N' and the line N1 is in the range of 0mm-0.8mm, that is, the most front end of the side electrode projects beyond the projection of the center electrode 3, so that the front end of the side electrode 4 is at a good ignition distance from the ignition end surface 31 of the center electrode 3, which facilitates ignition of the spark plug.

[0051] In summary, the application is provided with an opening part 411 at the front end part 41 of the side electrode 4, and the projection of the center electrode ignition end face Z1 in the center electrode axis direction AL is such that the projection face S2 of the center electrode ignition end face Z1 on the vertical plane Z of the center electrode axis falls completely within the projection face S1 of the opening part 411 on the vertical plane Z of the center electrode 3 axis, so that the center electrode 3 ignition end face is not blocked, and the opening part 411 forms two relatively sharp end parts of the front end part 41 of the side electrode 4, which can not only reduce the oil 5 attached to the side electrode 4, but also shorten the distance between the front end of the side electrode 4 and the outer edge of the ignition end part of the center electrode 3 away from the rear end part of the side electrode, thereby greatly enhancing the oil droplet accumulation resistance of the spark plug jumping gap; the ignition end of the center electrode 3 is relatively thin and the radius of the center electrode ignition end face is further limited, so that the oil is more difficult to adhere to the center electrode 3 ignition end face and the relatively sharp end part of the opening part of the side electrode 4, thereby solving the problem of oil accumulation between the two electrodes of the spark plug, greatly enhancing the oil droplet accumulation resistance of the spark plug jumping gap, improving the ignition performance of the spark plug, and further making the fuel burn more fully, and the fuel is not attached between the electrodes, which greatly improves the anti-carbon deposition capacity of the spark plug; by further limiting the angle of the opening part 411 of the side electrode 4, the ignition performance of the spark plug is good and the electrode can be quickly heated at low temperature; by setting the width of the side electrode 4, the side electrode 4 can also be quickly cooled at high temperature, thereby ensuring the service life of the spark plug; and the ignition performance of the spark plug is greatly improved.

[0052] The above examples are only for illustrating the application, not limiting the application, and those skilled in the art can make various changes or modifications without departing from the spirit and scope of the application, therefore all equivalent technical solutions should belong to the protection scope of the application, and the protection scope of the application should be defined by the claims.

Claims

1. A spark plug comprising a rod-shaped center electrode extending in an axial direction AL, an insulator having a shaft hole extending in the axial direction and holding the center electrode in the shaft hole, the center electrode being disposed at a front end side of the insulator, a metal shell surrounding and holding the insulator in a circumferential direction, a rear end of the insulator extending out of the metal shell in the axial direction, and a side electrode, a front end portion of the side electrode being disposed in a horizontal direction, a rear end portion of the side electrode being disposed in the axial direction AL of the center electrode, the rear end portion of the side electrode being welded to a front end face of the metal shell, characterized in that: The front end of the side electrode is provided with an opening part, the center electrode axis is set as line P, the vertical plane of the center electrode axis P is set as Z plane, the ignition end surface of the center electrode is set as Z1 plane; the projection of the opening part of the side electrode on the Z plane is set as S1 plane along the center electrode axis direction AL, the projection of the ignition end surface Z1 plane of the center electrode on the Z plane is set as S2 plane along the center electrode axis direction AL; then S2 plane is completely in S1 plane.

2. A spark plug according to claim 1, characterized in that: Along the horizontal direction, the center line of the front end of the side electrode is set as L, the center line L is consistent with the opening direction of the opening part of the side electrode; the perpendicular line perpendicular to the center line L and passing through the opening bottom of the side electrode is set as M, the perpendicular line perpendicular to the center line L and passing through the opening top of the side electrode is set as N; the projection plane of the front end of the side electrode on the Z plane is set as S plane along the center electrode axis direction AL; the corresponding projection lines of the perpendicular line M and the perpendicular line N on the Z plane are set as M' and N' along the center electrode axis direction AL; The area of S plane between the projection line M' and the projection line N' is set as A1, the area of the projection plane S1 between the projection line M' and the projection line N' is set as A2, then the relationship between A1 and A2 satisfies: 0.06≤A2 / (A1+A2)≤0.

4.

3. The spark plug of claim 1, wherein: The radius of the Z1 plane is set as R, and the R satisfies: 0.2mm≤R≤0.8mm.

4. A spark plug according to any one of claims 1-3, characterized in that The opening part is V-shaped, U-shaped, frustum-shaped, square-shaped and cuboid-shaped, etc.

5. A spark plug according to claim 4, characterized in that The angle of the V-shaped opening part is set as θ, and the angle θ satisfies: 10°≤θ≤80°.

6. The spark plug of claim 2 wherein: The projection line of the center line L on the Z plane is set as L' along the center electrode axis direction AL, and the two tangent lines M1 and N1 of the S2 plane are drawn, the line M1 and the line N1 are both perpendicular to the projection line L', and the line M1 is close to the opening bottom side; The area of S plane between the tangent line M1 and the tangent line N1 is set as B1, and the area of S1 plane between the tangent line M1 and the tangent line N1 is set as B2, then the relationship between B1 and B2 satisfies: 0.1≤B2 / B1≤2.

7. The spark plug of claim 1 wherein: The width of the side electrode is set as D, and the D satisfies: 2mm≤D≤3.2mm.

8. The spark plug of claim 6 wherein: The distance between the line N' and the line N1 is set as C, and the C satisfies: 0mm≤C≤0.8mm.

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