Spark plug

Abstract

Disclosed in the present invention is a spark plug, comprising a metal shell. The metal shell comprises a sealing protrusion portion, an annular groove portion and a thread portion. A solid annular sealing component is arranged at the annular groove portion, and comprises: a first horizontal surface and a second horizontal surface which are located on the rear end side, wherein the first horizontal surface is closer to the sealing protrusion portion of the spark plug than the second horizontal surface; a third horizontal surface and a fourth horizontal surface which are located on the front end side, wherein the third horizontal surface is closer to the thread portion of the spark plug than the fourth horizontal surface; and an outer circumferential surface and an inner circumferential surface, wherein the first horizontal surface, the second horizontal surface, the inner circumferential surface, the fourth horizontal surface, the third horizontal surface and the outer circumferential surface are sequentially combined and connected. In the circumferential direction, a plurality of recessed portions are provided on the fourth horizontal surface, and a protruding portion is formed on the second horizontal surface corresponding to the position of each recessed portion; and in the axial direction, the axial height by which each protruding portion protrudes from the second horizontal surface is set to be H, the axial distance between the second horizontal surface and the fourth horizontal surface is set to be L, the axial distance between the first horizontal surface and the third horizontal surface is set to be T, and the condition H<(T-L) / 2 is satisfied.

Description

A spark plug Technical Field

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

[0002] With increasingly stringent emission regulations, the combustion efficiency of engines is required to reach a higher level. Therefore, there is an urgent hope for the improvement of ignition technology, among which the ignition position of the spark plug is expected to be more precise. In the past, stacked multi-layer annular sealing components were used to achieve the sealing between the spark plug and the engine. However, since the axial height of the stacked annular sealing components cannot be achieved very accurately after the spark plug is installed, it will affect the ignition position and make it impossible for the engine to achieve more precise ignition. Therefore, solid annular seals are used in engines with high combustion efficiency. However, solid annular sealing components are not easy to be reliably fixed on the spark plug, and are prone to installation and falling off or it is difficult to achieve a good balance between leakage and installation, thereby causing a decrease in the airtightness or installation performance of the spark plug.

[0003] As shown in Figure 1, a spark plug comprises a rod-shaped center electrode 1 extending along an axis AL; an insulator 2 having an axial bore extending along the axis and retaining the center electrode 1 within the bore. The center electrode 1 is disposed at the front end of the insulator 2 (the arrow in the figure indicates the front end in the TP direction, and the opposite direction, the TX direction, indicates the rear end); a metal shell 3 circumferentially surrounding and retaining the insulator 2, with the rear end of the insulator 2 extending out of the metal shell 3 along the axis; and a side electrode 4, the rear end of which is welded to the front end of the metal shell 3. The metal shell 3 comprises a sealing boss 311, an annular groove 312, and a threaded portion 313, arranged in order from the rear end toward the front end along the axis AL. During installation, the spark plug is screwed onto the engine cover of an internal combustion engine via the threaded portion 313.

[0004] The solid annular sealing component mentioned above is not easy to be reliably fixed on the spark plug and is prone to falling off during installation. This means that before the spark plug is installed on the engine cover of the internal combustion engine, as shown in Figure 2, a solid annular sealing component 5 will be put on the annular groove portion 312 of the spark plug. When the spark plug is installed on the engine cover of the internal combustion engine, the sealing boss portion 311 of the spark plug is used to press the solid annular sealing component 5 onto the engine cover of the internal combustion engine (not shown in the figure) to ensure the airtightness in the engine combustion chamber. However, before being installed on the engine cover, it is necessary to ensure that the solid annular sealing component 5 does not fall off the spark plug. Therefore, in the prior art, after the solid annular sealing component 5 is placed on the annular groove portion 312 of the spark plug, a load is applied to the front end face of the solid annular sealing component 5 through a tooling die, thereby causing the inner peripheral portion of the solid annular sealing component 5 to protrude inwardly, so that the minimum inner diameter d of the solid annular sealing component 5 is less than the outer diameter of the spark plug's threaded portion 313. In this way, when the solid annular sealing component 5 falls along the spark plug's axial direction AL, the spark plug's threaded portion 313 can prevent the solid annular sealing component 5 from falling off. In addition, as the load is applied to the front end face of the solid annular sealing component 5, a recess 6 is formed on the front end face of the solid annular sealing component 5.

[0005] However, a problem existing in the prior art is that when the spark plug with a solid annular sealing component is installed on the engine cover, it often cannot be installed smoothly or is not installed properly, resulting in a loose seal between the spark plug and the engine cover, thereby causing a decrease in the installation performance and airtightness of the spark plug.

[0006] Similar patent documents are found as follows:

[0007] 1. A Japanese patent with publication number JP7247714B2, published on March 29, 2023, discloses a gasket for a spark plug, which is used when the spark plug is installed on the wall of the cylinder head of an internal combustion engine, and a plurality of inclined portions, wherein the plurality of inclined portions extend from the entirety of each of the protrusions toward the specific surface in the circumferential direction of the main body to a position closer to the front than the extended surface of the specific surface, and are inclined in a manner separated from the inner circumferential surface of the main body, the inclined portion being separated from the main body except for the connection portion connected to the protrusion, and the plurality of protrusions protrude at equal intervals from each other at the end portion of the main body on the side opposite to the specific surface on the wall side from the inner circumferential surface of the main body with the smallest inner diameter to the radial inside with a thickness thinner than the main body.

[0008] 2. A Chinese invention patent with authorization announcement number CN104995806B and authorization announcement date December 28, 2016 discloses a spark plug, comprising: a main metal shell having a through hole in an axial direction; and a gasket in a solid annular shape, arranged on the outer periphery of the main metal shell, the main metal shell having: an external threaded portion formed on the outer periphery of the front end side of the main metal shell itself for use during installation; and a seat portion formed at a position closer to the rear end side than the external threaded portion and bulging radially outward, the gasket being arranged between the external threaded portion and the seat portion, the spark plug being characterized in that an opening of a recess is formed on a surface of the gasket located on a side opposite to the side where the seat portion is located, the recess having a depth in the axial direction, the gasket having at least: an inner peripheral front end surface, which is perpendicular to the center axis of the gasket and passes through the rear end of the recess. When it is a reference plane, the distance from the above-mentioned reference plane gradually decreases as it goes toward the inner circumference; and the outer circumferential front end surface, which is located at a position closer to the outer circumference than the above-mentioned inner circumferential front end surface, the opening of the above-mentioned recess is formed at a position closer to the inner circumference than the innermost circumferential part of the above-mentioned outer circumferential front end surface, in a cross-section including the above-mentioned center axis and passing through the rear end of the above-mentioned recess, the shortest distance from the point of the above-mentioned gasket located at a position closer to the front end side than the above-mentioned reference plane and closest to the above-mentioned center axis to the above-mentioned center axis is set as L1, and the shortest distance from the point of the above-mentioned gasket located at a position closer to the rear end side than the above-mentioned reference plane and closest to the above-mentioned center axis to the above-mentioned center axis is set as L2, at this time, L1<L2, and in a cross-section including the above-mentioned axis of the above-mentioned main metal shell, the acute angle formed by the surface of the above-mentioned seat portion located on the side where the above-mentioned gasket is located and the imaginary line perpendicular to the above-mentioned axis of the above-mentioned main metal shell is greater than 0.5° and less than 6°.

[0009] The spark plugs disclosed in the above patent documents all have the above technical problems when being installed, and no relevant solutions are disclosed in the above patent documents.

[0010] To sum up, how to design a spark plug so that it can not only ensure that the solid annular sealing component mounted on the spark plug does not fall off before being assembled on the engine cover, but also ensure that the spark plug can be assembled on the engine cover smoothly without problems of not being able to proceed smoothly or not being installed in place, and ensure the sealing performance, thereby ensuring the installation performance and airtightness of the spark plug is a technical problem that needs to be solved urgently. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a spark plug in response to the defects existing in the prior art, which can not only ensure that the solid annular sealing component sleeved on the spark plug does not fall off before being assembled on the engine cover, but also ensure that the spark plug can be smoothly assembled on the engine cover without problems of failure to proceed smoothly or improper installation, and without problems of reduced sealing performance, thereby ensuring the installation performance and airtightness of the spark plug.

[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a spark plug comprising a rod-shaped center electrode extending along an axis AL; an insulator having an axial hole extending along the axial direction and retaining the center electrode within the axial hole, the center electrode being disposed on the front end side of the insulator; a metal shell circumferentially surrounding and retaining the insulator, the rear end of the insulator extending out of the metal shell along the axial direction; and a side electrode having a rear end welded to a front end surface of the metal shell, the rear end of the side electrode being bonded to the front end surface of the metal shell.

[0013] The metal shell includes a sealing boss portion, an annular groove portion and a threaded portion arranged in sequence from the rear end side to the front end side along the axis AL;

[0014] A solid annular sealing component is further provided outside the metal shell and located at the annular groove portion, the solid annular sealing component including a first horizontal surface and a second horizontal surface located at the rear end side, wherein the first horizontal surface is closer to the sealing boss portion of the spark plug than the second horizontal surface; a third horizontal surface and a fourth horizontal surface located at the front end side, wherein the third horizontal surface is closer to the threaded portion of the spark plug than the fourth horizontal surface; an outer peripheral surface and an inner peripheral surface, wherein the inner peripheral surface is closer to the central axis AL of the spark plug than the outer peripheral surface, wherein the first horizontal surface, the second horizontal surface, the inner peripheral surface, the fourth horizontal surface, the third horizontal surface and the outer peripheral surface are enclosed and connected in sequence;

[0015] Along the circumference of the solid annular sealing component, a plurality of recesses are provided on the fourth horizontal plane, and corresponding to the position of each recess, a convex portion is formed on the second horizontal plane; along the axial direction, the axial height of the convex portion protruding from the second horizontal plane is set to H, the axial distance between the second horizontal plane and the fourth horizontal plane is set to L, and the axial distance between the first horizontal plane and the third horizontal plane is set to T, then the condition H<(TL) / 2 is satisfied.

[0016] Preferably, the axial distance L between the second horizontal plane and the fourth horizontal plane is set to: L≥1.2 mm.

[0017] Preferably, the diameter E of the annular groove is set to: E≤10.8 mm.

[0018] Preferably, the axial height of the annular groove portion 312 is set to F, and F is ≥ 1.8 mm.

[0019] Preferably, the inner peripheral surface is configured as a curved surface.

[0020] Preferably, a proximity point A closest to the center axis AL of the spark plug is provided on the inner peripheral surface of the curved surface; when the threaded portion specification of the spark plug is M12, the distance between the proximity point A and the center axis AL is set to B, and the distance B is set to: 5.2mm≤B≤5.9mm.

[0021] Preferably, an arc-shaped connecting portion is provided between the sealing boss portion and the annular groove portion of the spark plug metal shell, and the sealing boss portion and the annular groove portion are connected by the arc-shaped connecting portion. An arc portion whose curvature matches the arc-shaped connecting portion is also provided on the curved inner circumferential surface of the solid annular sealing component.

[0022] Preferably, the radius R of the arc-shaped connecting portion is set to: R≤1.0 mm.

[0023] Preferably, the radius R of the arc-shaped connecting portion is set to: R=0.7 mm.

[0024] Preferably, the material of the solid annular sealing component consists of at least three materials among Gr, Mg, Si, Cu, Zn, Ti, and Ni and the remainder Al, wherein when the at least three materials include Ti and Ni, the preferred range is 0.05 to 0.2wt% Ti and 0.1 to 0.5wt% Ni.

[0025] The beneficial effects of the present invention are as follows: Due to the structural design of the present invention, even if the recess is made deeper and closer to the rear end of the solid annular sealing component by tooling, the axial height H of the protrusion will not exceed the height of the first horizontal plane, thereby preventing the protrusion protruding from the first horizontal plane from hitting the sealing boss of the spark plug during assembly, thereby reducing the installation performance and airtightness of the spark plug. By setting the axial distance L between the second horizontal plane and the fourth horizontal plane, the radial distance between the inner circumferential surface and the central axis AL of the spark plug can be more reliably reduced, thereby allowing the solid annular sealing component to be more securely retained on the spark plug and prevented from falling off. By setting the inner circumferential surface as a curved surface, even if the curved inner circumferential surface of the solid annular sealing component collides with the spark plug during transportation, it will not cause damage to the solid annular sealing component or the spark plug, thereby improving product quality. When the threaded portion of the spark plug has a specification of M12, by setting a distance B between the approach point A and the central axis AL, the solid annular sealing component is less likely to fall off and does not interfere with the annular groove of the spark plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic diagram of an axial cross-sectional structure of a spark plug in the prior art;

[0027] FIG2 is a schematic diagram of a partial axial cross-sectional structure of a solid annular sealing component after a spark plug is sleeved with the solid annular sealing component in the prior art;

[0028] FIG3 is a schematic diagram of a partial axial cross-sectional structure of a solid annular sealing component after the spark plug is sleeved with the solid annular sealing component in an embodiment of the present invention;

[0029] FIG4 is a schematic diagram of a partial axial cross-sectional structure of a solid annular sealing component in an embodiment of the present invention;

[0030] FIG5 is an enlarged structural diagram of portion C in FIG3 ;

[0031] In the figure: 1. Center electrode, 2. Insulator, 3. Metal shell, 311. Sealing boss portion, 312. Annular groove portion, 313. Threaded portion, 314. Arc-shaped connecting portion, 4. Side electrode, 5. Solid annular sealing component, 511. First horizontal plane, 512. Second horizontal plane, 513. Third horizontal plane, 514. Fourth horizontal plane, 515. Outer circumferential surface, 516. Inner circumferential surface, 517. Arc portion, 6. Concave portion, 7. Protrusion. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] After research, the applicant found that, as shown in Figure 2, the reason why the spark plug is not properly installed is that when the tooling die applies a load on the front end face of the solid annular sealing component 5 to form the recess 6, a convex portion is formed at the position corresponding to the recess 6 and on the rear end face of the solid annular sealing component 5. The convex portion sometimes protrudes too high and hits the sealing boss portion 311 of the spark plug when the spark plug is installed, resulting in a decrease in the contact area between the sealing boss portion 311 of the spark plug and the solid annular seal 5, thereby making it impossible to install the spark plug smoothly or to install it improperly, resulting in a poor seal, which in turn leads to a decrease in the installation performance and airtightness of the spark plug.

[0034] Example:

[0035] To this end, the applicant has improved the solid annular sealing component as follows:

[0036] As shown in Figures 3 and 4 , the solid annular sealing member 5 in this embodiment is also sleeved onto the annular groove 312 of the spark plug and positioned between the sealing boss 311 and the threaded portion 313 of the spark plug. The solid annular sealing member 5 includes a first horizontal surface 511 and a second horizontal surface 512 located on the rear end side (TX), wherein the first horizontal surface 511 is closer to the sealing boss 311 of the spark plug than the second horizontal surface 512; a third horizontal surface 513 and a fourth horizontal surface 514 located on the front end side (TP), wherein the third horizontal surface 513 is closer to the threaded portion 313 of the spark plug than the fourth horizontal surface 514; an outer circumferential surface 515 and an inner circumferential surface 516, wherein the inner circumferential surface 516 is closer to the central axis AL of the spark plug than the outer circumferential surface 515. The first horizontal surface 511, the second horizontal surface 512, the inner circumferential surface 516, the fourth horizontal surface 514, the third horizontal surface 513, and the outer circumferential surface 515 are sequentially enclosed and connected. Along the circumference of the solid annular sealing component 5, a plurality of recesses 6 are provided on the fourth horizontal surface 514. The number of recesses 6 can be three, four, six, or eight, distributed on the fourth horizontal surface 514. Corresponding to the position of each recess 6, a protrusion 7 is formed on the second horizontal surface 512. In the axial direction, if the axial height of the protrusion 7 above the second horizontal surface 512 is H, the axial distance between the second horizontal surface 512 and the fourth horizontal surface 514 is L, and the axial distance between the first horizontal surface 511 and the third horizontal surface 513 is T, then the condition H < (TL) / 2 is satisfied. Within this range, even if the depth of the recess 6 is made deeper and closer to the rear end side of the solid annular sealing component due to the processing of the tooling die, the axial height H of the protrusion 7 will not be too high, that is, the protrusion 7 will not protrude above the height of the first horizontal plane 511, thereby avoiding the problem that the protrusion 7 protruding above the first horizontal plane 511 hits the sealing boss 311 of the spark plug when the spark plug is assembled, causing a decrease in the contact area between the sealing boss 311 of the spark plug and the solid annular seal 5, resulting in a decrease in the installation performance and airtightness performance of the spark plug.

[0037] The axial distance L between the second horizontal plane 512 and the fourth horizontal plane 514 is set to: L≥1.2mm, which can more reliably ensure that the radial distance between the inner circumferential surface and the central axis AL of the spark plug becomes smaller, so that the solid annular sealing component can be more reliably retained on the spark plug to prevent it from falling off.

[0038] The following experimental data demonstrates the effect of the improved solid annular sealing component on the above-mentioned sealing performance and anti-falling properties:

[0039] The steps are as follows: according to different specifications of axial height H, axial distance L and whether the condition of H < (TL) / 2 is met, spark plug samples one to six are produced respectively, and then the six spark plug samples are subjected to anti-dropping test and air tightness test:

[0040] Anti-fall test: Rotate the solid annular sealing component clockwise with a torque not exceeding 1.5 NM. Samples that can be easily rotated and cannot be unscrewed are rated as excellent, marked as ◎; samples that can be easily rotated and cannot be unscrewed are rated as good, marked as ○; samples that cannot be rotated are rated as poor, marked as △; samples that can be easily rotated and can be unscrewed are rated as poor, marked as △;

[0041] Airtightness test: The airtightness test is carried out in accordance with the hot sealing performance test method specified in China GB / T7825. The result of no air leakage is evaluated as excellent and recorded as ◎, the result of air leakage less than 2ML / min is evaluated as qualified and recorded as ○, and the result of air leakage above 2ml / min is evaluated as unqualified and recorded as △;

[0042] The specific data and test results are shown in the following table

[0043] Through the above experimental numerical control, it can be seen that samples 3, 4 and 5 can make the solid annular sealing components meet the requirements of air tightness and anti-falling at the same time, and perform well in these two aspects.

[0044] As shown in Figure 4, the inner circumferential surface 516 is configured as a curved surface. In the prior art, the inner circumferential surface of a solid annular sealing component is provided with a sharp corner. Therefore, when a spark plug having a solid annular sealing component is transported, the sharp corner of the inner circumferential surface of the solid annular sealing component may collide with the spark plug, causing damage to the solid annular sealing component and localized wear of the spark plug, thereby reducing product quality. In this embodiment, the inner circumferential surface 516 is configured as a curved surface. Even if the curved inner circumferential surface of the solid annular sealing component collides with the spark plug during transportation, neither the solid annular sealing component nor the spark plug will be damaged, thereby improving product quality.

[0045] Through research, the applicant discovered that when the threaded portion of a spark plug is M12, a proximity point A is provided on the curved inner peripheral surface 516, closest to the central axis AL of the spark plug. This proximity point A is located near the front end of the spark plug, and the distance between this proximity point A and the central axis AL is set to B. Distance B is set to: 5.2 mm ≤ B ≤ 5.9 mm. This arrangement makes the solid annular sealing component less likely to fall off and prevents interference with the annular groove of the spark plug.

[0046] The following experimental data demonstrates the improvement of the above-mentioned shedding and interference of the improved solid annular sealing component:

[0047] The steps are as follows: a plurality of spark plug samples are respectively produced, each having a threaded portion having a diameter of M12; the solid annular sealing component sleeved on the spark plug sample adopts the solid annular sealing component of this embodiment, and the distance between the closest point A on the inner circumferential surface and the central axis AL is set to B. Among them, the distance B of the solid annular sealing component on the spark plug sample one is 5.1 mm, the distance B of the solid annular sealing component on the spark plug sample two is 6.0 mm, the distance B of the solid annular sealing component on the spark plug sample three is 5.4 mm, the distance B of the solid annular sealing component on the spark plug sample four is 5.6 mm, the distance B of the solid annular sealing component on the spark plug sample five is 5.2, and the distance B of the solid annular sealing component on the spark plug sample six is ​​5.9. The advantages and disadvantages of each sample were evaluated in the following way: the solid annular sealing component was rotated clockwise with a torque not exceeding 1.5 NM. The sample that could be easily rotated and could not unscrew the first thread from the rear end of the threaded portion was evaluated as excellent and recorded as ◎; the sample that could be easily rotated and could not unscrew the second thread from the rear end of the threaded portion was evaluated as good and recorded as ○; the sample that could not be rotated was evaluated as poor and recorded as △; the sample that could be easily rotated and could unscrew the second thread from the rear end of the threaded portion was evaluated as poor and recorded as △. The test results are shown in the following table.

[0048] It can be seen from the above test data that samples 5 and 6 are evaluated as good, samples 3 and 4 are evaluated as excellent, and the solid annular sealing gaskets of the four samples can be reliably fixed without interference. Samples 1 and 2 are evaluated as unqualified, and they cannot achieve good fixation and prevent interference.

[0049] As shown in FIG5 , the applicant has also improved the spark plug itself by providing an arc-shaped connecting portion 314 between the sealing boss portion 311 and the annular groove portion 312 of the spark plug metal shell. The arc-shaped connecting portion 314 connects the sealing boss portion 311 and the annular groove portion 312. An arc portion 517 having a curvature matching that of the arc-shaped connecting portion 314 is also provided on the curved inner circumference 516 of the solid annular sealing component 5. When the spark plug is installed, the arc-shaped connecting portion on the spark plug metal shell cooperates with the arc portion on the inner circumference of the annular sealing component, further improving reliable fixed installation performance and airtightness. The radius R of the arc-shaped connecting portion 314 is set to: R≤1.0mm, preferably less than 0.8mm, such as 0.7mm. This can further prevent interference between the solid annular sealing component and the arc-shaped connecting portion. The diameter E of the annular groove 312 is set to: E≤10.8 mm, so that the solid annular seal can be sufficiently deformed in the radial direction when the recess is processed, further ensuring that it is not easy to fall off.

[0050] The annular groove portion 312 has a certain height in the axial direction. The axial height is set to F, and F≥1.8 mm, which can further meet the installation requirements of the solid annular sealing component.

[0051] To further enhance the airtightness of the spark plug after installation, the applicant has also improved the material of the solid annular sealing component, namely, the material of the solid annular sealing component is composed of at least three materials among Gr, Mg, Si, Cu, Zn, Ti, and Ni, and the balance Al. When the at least three materials include Ti and Ni, the preferred range is 0.05 to 0.2 wt% Ti and 0.1 to 0.5 wt% Ni. The Ti and Ni composition in this ratio can improve the grain size of the solid annular sealing component, refine its grain size, increase the ductility of the solid annular sealing component, and thus improve the airtightness of the spark plug after installation. After further research, the applicant found that the more preferred range is 0.1 to 0.2 wt% Ti and 0.3 to 0.5 wt% Ni.

[0052] In summary, after the structural design of the present invention, even if the depth of the recess is made deeper and closer to the rear end side of the solid annular sealing component by processing the tooling die, the axial height H of the protrusion will not protrude above the height of the first horizontal plane, thereby avoiding the problem that the protrusion protruding above the first horizontal plane hits the sealing boss of the spark plug during assembly, resulting in a decrease in the installation performance and airtightness of the spark plug. By setting the axial distance L between the second horizontal plane and the fourth horizontal plane, it is possible to more reliably ensure that the radial distance between the inner circumferential surface and the central axis AL of the spark plug is reduced, so that the solid annular sealing component can be more reliably retained on the spark plug and prevented from falling off. By setting the inner circumferential surface as a curved surface, during transportation, even if the curved inner circumferential surface of the solid annular sealing component collides with the spark plug, it will not cause damage to the solid annular sealing component and the spark plug, thereby improving the quality of the product. When the threaded portion of the spark plug is M12, by setting the distance B between the approach point A and the central axis AL, the solid annular sealing component is less likely to fall off and does not interfere with the annular groove of the spark plug.

[0053] The term "plurality" in the above embodiments refers to "two or more." The above embodiments are intended to illustrate the present invention only and are not intended to limit the present invention. Persons skilled in the art may make various modifications or alterations without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions are intended to fall within the scope of protection of the present invention, which is defined by the claims.

Claims

1. A spark plug comprising: a rod-shaped center electrode extending in the direction of an axis AL; an insulator having an axial hole extending in the axial direction and holding the center electrode therein, the center electrode being disposed on the front end side of the insulator; a metal shell circumferentially surrounding and holding the insulator, the rear end of the insulator extending out of the metal shell in the axial direction; and a side electrode having a rear end welded to a front end surface of the metal shell, the rear end of the side electrode being bonded to the front end surface of the metal shell. The metal shell includes a sealing boss portion, an annular groove portion and a threaded portion arranged in sequence from the rear end side to the front end side along the axis AL; A solid annular sealing component is provided outside the metal shell and located at the annular groove, and is characterized in that: The solid annular sealing component includes a first horizontal surface and a second horizontal surface located at the rear end side, wherein the first horizontal surface is closer to the sealing boss portion of the spark plug than the second horizontal surface; a third horizontal surface and a fourth horizontal surface located at the front end side, wherein the third horizontal surface is closer to the threaded portion of the spark plug than the fourth horizontal surface; an outer peripheral surface and an inner peripheral surface, wherein the inner peripheral surface is closer to the central axis AL of the spark plug than the outer peripheral surface, wherein the first horizontal surface, the second horizontal surface, the inner peripheral surface, the fourth horizontal surface, the third horizontal surface and the outer peripheral surface are enclosed and connected in sequence; Along the circumference of the solid annular sealing component, a plurality of recesses are provided on the fourth horizontal plane, and corresponding to the position of each recess, a convex portion is formed on the second horizontal plane; along the axial direction, the axial height of the convex portion protruding from the second horizontal plane is set to H, the axial distance between the second horizontal plane and the fourth horizontal plane is set to L, and the axial distance between the first horizontal plane and the third horizontal plane is set to T, then the condition H<(TL) / 2 is satisfied.

2. The spark plug according to claim 1, wherein: The axial distance L between the second horizontal plane and the fourth horizontal plane is set to: L≥1.2 mm.

3. The spark plug according to claim 2, wherein: The diameter E of the annular groove portion is set to: E≤10.8 mm.

4. The spark plug according to claim 3, wherein: The axial height of the annular groove portion 312 is set to F, and F is ≥ 1.8 mm.

5. The spark plug according to any one of claims 1 to 4, characterized in that: The inner peripheral surface is configured as a curved surface.

6. The spark plug according to claim 5, characterized in that: A proximity point A closest to the center axis AL of the spark plug is provided on the inner peripheral surface of the curved surface; when the threaded portion specification of the spark plug is M12, the distance between the proximity point A and the center axis AL is set to B, and the distance B is set to: 5.2mm≤B≤5.9mm.

7. The spark plug according to claim 6, wherein: An arc-shaped connecting portion is provided between the sealing boss portion and the annular groove portion of the spark plug metal shell, and the sealing boss portion and the annular groove portion are connected by the arc-shaped connecting portion. An arc portion whose curvature matches the arc-shaped connecting portion is also provided on the curved inner circumferential surface of the solid annular sealing component.

8. The spark plug according to claim 7, wherein: The radius R of the arc-shaped connecting portion is set to: R≤1.0 mm.

9. The spark plug according to claim 8, wherein: The radius R of the arc-shaped connecting portion is set to: R=0.7 mm.

10. The spark plug according to any one of claims 1 to 4, characterized in that: The material of the solid annular sealing component consists of at least three materials among Gr, Mg, Si, Cu, Zn, Ti, and Ni and the remainder Al, wherein when the at least three materials include Ti and Ni, the range is 0.05 to 0.2wt% Ti and 0.1 to 0.5wt% Ni.

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