Spark plug for clean energy fuel engine

Abstract

The utility model discloses a spark plug for a clean energy fuel engine, which comprises a rod-shaped central electrode extending along the axis direction; an insulator having a shaft hole extending in the axial direction and holding the center electrode in the shaft hole, the center electrode being provided at the tip of the insulator; a metal housing surrounding and holding the insulator in the circumferential direction, the rear end of the insulator extending out of the metal housing in the axial direction; the side electrode is annular, an annular installation groove is formed in the circumferential face of the inner side of the front end of the metal shell, the annular side electrode is installed in the annular installation groove, the front end face of the annular side electrode is flush with the front end face of the metal shell, or the front end face of the annular side electrode is exposed out of the front end face of the metal shell. And the front end of the central electrode extends into the central hole of the annular side electrode, and a flashover gap H is reserved between the outer peripheral surface of the front end of the central electrode and the inner peripheral surface of the central hole of the annular side electrode.

Description

Technical Field

[0001] This utility model relates to a spark plug, and more particularly to a spark plug for a clean energy fuel engine, belonging to the field of spark plug manufacturing technology. Background Technology

[0002] Clean energy fuel engines are engines that use clean energy sources (such as natural gas, hydrogen, methanol, ethanol, etc.) as fuel to generate power through combustion. They have the following characteristics: 1. Environmental friendliness: The fuels used in clean energy fuel engines typically have low emissions. For example, natural gas combustion produces virtually no particulate matter and very little CO. Hydrogen fuel engines, on the other hand, only produce heat and water, with no pollutant emissions. 2. High efficiency: Clean energy fuel engines typically have high energy conversion efficiency, especially hydrogen fuel engines, whose energy conversion rate is far higher than that of traditional fuel internal combustion engines. 3. Sustainability: Clean energy fuels such as natural gas and hydrogen are usually renewable or sustainably usable, helping to reduce dependence on traditional fossil fuels.

[0003] Clean energy fuel engines also have some problems. For example, hydrogen fuel engines are prone to pre-ignition knocking due to the pre-ignition properties of hydrogen fuel. If traditional spark plugs are used in hydrogen fuel engines, pre-ignition knocking often occurs during operation due to overheating of the ceramic parts, center electrode, or side electrode. In addition, the L-shaped side electrode of traditional spark plugs is also prone to hydrogen embrittlement, leading to side electrode detachment.

[0004] In summary, designing a spark plug for a clean energy fuel engine that can reduce its temperature during operation to prevent pre-ignition knocking caused by overheating, and that can mitigate hydrogen embrittlement between the side electrode and hydrogen gas to reduce the risk of side electrode detachment, are urgent technical problems that need to be solved. Utility Model Content

[0005] The technical problem to be solved by this utility model is to address the problems existing in the prior art by providing a spark plug for a clean energy fuel engine. During operation, the spark plug can reduce its own temperature, avoid pre-ignition knocking caused by overheating of the spark plug, and reduce the degree of hydrogen embrittlement between the side electrode and hydrogen, thereby reducing the risk of side electrode detachment.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: a spark plug for a clean energy fuel engine, comprising a rod-shaped center electrode extending along the axial direction; an insulator having a shaft hole extending along the axial direction and holding the center electrode in the shaft hole, the center electrode being disposed at the front end of the insulator; a metal shell surrounding and holding 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 side electrode being annular, with an annular mounting groove provided on the inner circumferential surface of the front end of the metal shell, the annular side electrode being installed in the annular mounting groove, the front end face of the annular side electrode being flush with the front end face of the metal shell or the front end face of the annular side electrode being exposed outside the front end face of the metal shell, the distance of the front end face of the annular side electrode being exposed outside the front end face of the metal shell being denoted as A, then 0mm < A ≤ 2mm, the front end of the center electrode extending into the center hole of the annular side electrode and a spark gap H being left between the outer circumferential surface of the front end of the center electrode and the inner circumferential surface of the center hole of the annular side electrode.

[0007] Preferably, the insulator near the front end of the insulator is in contact with the inner circumferential surface of the metal shell through a washer. The insulator between the washer and the front end face of the insulator is the skirt of the insulator. The length of the skirt is set as skirt length B, then 3mm≤skirt length B≤7mm.

[0008] Preferably, the space formed by the gasket, the skirt of the insulator, the inner circumferential surface of the metal shell, and the annular side electrode is a heat storage chamber, and its volume is set to V; the volume V of the heat storage chamber is set to V≤25mm. 3 .

[0009] Preferably, the distance between the front end face of the insulator skirt and the rear end face of the annular side electrode is set as D, then the distance D≤0.5mm.

[0010] Preferably, the outer peripheral surface of the skirt of the insulator is parallel to the inner peripheral surface of the metal shell.

[0011] Preferably, the distance between the outer circumferential surface of the skirt of the insulator and the inner circumferential surface of the metal shell is set as H, then H≤0.1mm.

[0012] Preferably, an exhaust port is provided on the annular side electrode, and the hot chamber of the spark plug communicates with the outside through the exhaust port.

[0013] Preferably, the area of ​​the annular end face of the annular side electrode is set as S1, and the area of ​​the exhaust hole is set as S2, then S2 / S1≥6%.

[0014] The beneficial effects of this utility model are as follows: Through structural design, the side electrode is designed as a ring, shifting its position backward compared to existing side electrodes. This allows the ring-shaped side electrode to be further away from the high-temperature area at the bottom of the engine cylinder, thus reducing its own temperature during operation and preventing pre-ignition knocking due to overheating. Furthermore, the structural design reduces the exposed surface area of ​​the ring-shaped side electrode compared to existing side electrodes, mitigating hydrogen embrittlement and reducing the risk of electrode detachment. Shortening the length of the insulator skirt reduces the heat absorption area and heat dissipation distance, increasing the spark plug's heat dissipation rate and further lowering its operating temperature, preventing pre-ignition knocking due to overheating. Reducing the volume of the heat chamber and the heat-receiving area of ​​the insulator skirt also reduces the heat absorbed by the spark plug during operation, further lowering its operating temperature. By providing an exhaust port on the annular side electrode, the exhaust gas inside the heat chamber can be discharged, allowing the spark plug to achieve better working performance. Attached Figure Description

[0015] Figure 1 A schematic diagram of the structure of a spark plug after it has been installed on an engine cylinder in the prior art;

[0016] Figure 2 This is a partial axial cross-sectional view of the spark plug in Embodiment 1 of this utility model;

[0017] Figure 3 for Figure 2 A schematic diagram of a partial axial cross-section of the structure located at the annular side electrode;

[0018] Figure 4 This is a three-dimensional structural diagram of the annular side electrode in Embodiment 1 of this utility model;

[0019] Figure 5 This is a schematic diagram of the structure after the spark plug is installed on the engine cylinder in Embodiment 1 of this utility model;

[0020] Figure 6 for Figure 3 Enlarged structural diagram of section E;

[0021] Figure 7 This is a partial axial cross-sectional view of the spark plug located at the annular side electrode in Embodiment 2 of the present invention.

[0022] In the diagram: 1. Spark plug, 2. Engine cylinder, 211. Mounting surface, 3. Center electrode, 4. Side electrode, 411. Exhaust port, 5. Metal housing, 511. Annular mounting groove, 512. Threaded part, 6. Insulator, 611. Skirt, 7. Washer, 8. Heat chamber. Detailed Implementation

[0023] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1: The applicant discovered through research that, Figure 1 As shown, when the existing spark plug 1 is installed on the mounting surface 211 of the engine cylinder 2, the center electrode 3 and side electrode 4 of the spark plug 1 extend into the engine cylinder 2. If the horizontal plane at the front end of the metal shell 5 of the spark plug 1 is defined as L, it can be seen that the position of the side electrode 4 of the existing spark plug 1 inside the engine cylinder 2 exceeds the horizontal plane L. That is, the side electrode 4 is closer to the high-temperature position at the bottom of the engine cylinder 2, which leads to overheating of the side electrode during operation, causing pre-ignition knocking in the hydrogen engine. Furthermore, the side electrode 4 of the existing spark plug 1 is generally L-shaped, with more of its surface exposed inside the engine cylinder. Therefore, the L-shaped side electrode is also highly susceptible to hydrogen embrittlement, leading to its detachment.

[0025] The applicant has made improvements to address the above issues, such as Figures 2 to 4 As shown, a spark plug includes a rod-shaped center electrode 3 extending along an axis AL; an insulator 6 having an axial bore extending along the axis and holding the center electrode 3 within the bore, the center electrode 3 being disposed at the front end of the insulator 6 (the arrow in the figure points to the front end in the TP direction, and the opposite direction TX points to the rear end); a metal housing 5 surrounding and holding the insulator 6 circumferentially, the rear end of the insulator 6 extending out of the metal housing 5 along the axis; and a side electrode 4, the side electrode 4 being annular, with an annular mounting groove 511 provided on the inner circumferential surface of the front end of the metal housing 5, the annular side electrode 4 being mounted (e.g., laser-welded) in the annular mounting groove 511, the front end face of the annular side electrode 4 being flush with the front end face of the metal housing 5, the front end of the center electrode 3 extending into the center bore of the annular side electrode 4, and a spark gap H being left between the outer circumferential surface of the front end of the center electrode 3 and the inner circumferential surface of the center bore of the annular side electrode 4. The annular side electrode 4 can be an annular nickel alloy side electrode, and the insulator 6 can be a ceramic component. Figure 2 and Figure 5As shown, the metal housing 5 includes a threaded portion 612. During spark plug installation, the spark plug is tightened onto the engine cylinder 2 via the threaded portion 612. In this embodiment, after the spark plug is installed, the front end face of the annular side electrode 4 is flush with the horizontal plane L where the front end face of the metal housing 5 is located within the engine cylinder 2. However, in existing technologies (such as...) Figure 1 As shown, the side electrode 4 of the spark plug in this embodiment is positioned above the horizontal plane L within the engine cylinder 2. Therefore, compared to existing spark plugs, the side electrode 4 is further away from the high-temperature position at the bottom of the engine cylinder 2, thus reducing its own temperature during operation and preventing pre-ignition knocking due to overheating. Furthermore, the annular side electrode 4 is installed in an annular mounting groove 511 on the inner circumferential surface of the front end of the metal housing 5. This effectively encloses the annular side electrode 4 within the metal housing 5, leaving only its front end exposed within the engine cylinder. In contrast, existing technologies (such as...) Figure 1 The L-shaped side electrode 4 shown in the figure is completely exposed inside the engine cylinder. Compared with the prior art, the annular side electrode 4 in this embodiment reduces the surface area exposed inside the engine cylinder, slows down the degree of hydrogen embrittlement between the side electrode and hydrogen, and thus reduces the risk of the side electrode falling off.

[0026] like Figure 3 As shown, the insulator 6 near its front end contacts the inner circumferential surface of the metal housing 5 via a washer 7. The insulator 6 between the washer 7 and the front end face of the insulator 6 forms the skirt 611 of the insulator 6. Let the length of the skirt 611 be defined as skirt length B, then: 3mm ≤ B ≤ 7mm. During operation, the outer surface area of ​​the skirt 611 is the heat absorption area, and the heat dissipation path is shown by the dotted line in the figure. Heat is transferred outward sequentially through the insulator 6, washer 7, and metal housing 5. In this embodiment, the skirt length B is limited to between 3mm and 7mm, which is consistent with existing technologies (such as...). Figure 1 Compared to the previous version (shown), it can be seen that the skirt length B of the 611mm version is significantly shorter. This reduces the heat absorption area of ​​the skirt and shortens the heat dissipation distance, increasing the heat dissipation rate of the spark plug and further reducing the operating temperature of the spark plug, thus preventing pre-ignition knocking caused by overheating. The applicant conducted an experiment, and the test data is as follows:

[0027]

[0028] The test data above shows that when the skirt length B is set between 3mm and 7mm, compared with existing technologies, it can reduce the temperature of the spark plug during operation.

[0029] like Figure 3As shown, the space enclosed by the gasket 7, the skirt 611 of the insulator 6, the inner circumferential surface of the metal shell 5, and the annular side electrode 4 forms a heat capacity chamber 8, the volume of which is V. Reducing the volume V of the heat capacity chamber 8 decreases the heated area, thereby reducing the heat received by the spark plug during operation and further lowering its operating temperature. Therefore, the applicant defines the distance between the front end face of the insulator skirt 611 and the rear end face of the annular side electrode 4 as D, where D ≤ 0.5 mm, and the optimal range is 0.2 mm ≤ D ≤ 0.5 mm.

[0030] In addition, to further reduce the volume V of the heat capacity chamber 8, the applicant has made improvements such as: Figure 3 and Figure 6 As shown, a gap F is left between the outer peripheral surface of the skirt 611 of the insulator and the inner peripheral surface of the metal shell 5. Since the space of the gap F is also part of the heat capacity chamber 8, if the volume of the space of the gap F can be further reduced, the volume V of the heat capacity chamber 8 can also be further reduced. In this embodiment, from Figure 6 As can be seen, if the outer peripheral surface of the insulator's skirt 611 is set to be outwardly inclined, i.e., at the H1 line position, it will be difficult to assemble the insulator 6 and the metal shell 5, and interference will be formed between them. If the outer peripheral surface of the insulator's skirt 611 is set to be inwardly inclined, i.e., at the H2 line position, it cannot be guaranteed that the gap F space is minimized. Therefore, only when the outer peripheral surface of the insulator's skirt 611 is set vertically, i.e., at the H3 line position, will the outer peripheral surface of the insulator's skirt 611 and the inner peripheral surface of the metal shell 5 be parallel to each other. This ensures that the gap F space is relatively small and that the assembly between the insulator and the metal shell can proceed smoothly. Let H be the distance between the outer peripheral surface of the insulator's skirt 611 and the inner peripheral surface of the metal shell 5. The preferred distance is H ≤ 0.1 mm, and the optimal range is 0.05 mm ≤ H ≤ 0.1 mm.

[0031] Additionally, when the volume V of the heat chamber 8 is set to V≤25mm 3 At this time, the optimal range is 5mm. 3 ≤V≤25mm 3 At this point, the spark plug's cooling effect is also quite good. The applicant conducted an experiment, and the test data is as follows:

[0032]

[0033] The above experimental data shows that when the volume V of the heat chamber 8 is set to V≤25m³, 3 This allows for better reduction of the spark plug's operating temperature.

[0034] like Figure 3 and Figure 4 As shown, an exhaust port 411 is provided on the annular side electrode 4. The hot chamber 8 of the spark plug communicates with the outside through the exhaust port 411. The exhaust port 411 allows the exhaust gas inside the hot chamber 8 to be discharged, enabling the spark plug to achieve better working performance. In this embodiment, multiple exhaust ports 411 are provided. Let the area of ​​the annular end face of the annular side electrode 4 be S1, and the orifice area of ​​the exhaust port 411 be S2. When S2 / S1≥6%, the exhaust effect is optimal.

[0035] Example 2: Figure 7 As shown, compared with Embodiment 1, the difference lies in that the front end face of the annular side electrode 4 is exposed outside the front end face of the metal housing 5. Let A be the distance between the front end face of the annular side electrode 4 and the front end face of the metal housing 5, then distance A is 0mm < A ≤ 2mm. This also avoids the occurrence of pre-ignition knocking in the engine due to overheating and reduces the risk of the side electrode detaching.

[0036] In summary, this invention, through structural design, makes the side electrode annular, shifting its position backward compared to existing side electrodes. This allows the annular side electrode to be further away from the high-temperature area at the bottom of the engine cylinder, thus reducing its temperature during operation and preventing pre-ignition knocking due to overheating. Furthermore, the structural design reduces the exposed surface area of ​​the annular side electrode compared to existing side electrodes, mitigating hydrogen embrittlement and reducing the risk of electrode detachment. Shortening the insulator skirt reduces the heat absorption area and heat dissipation distance, increasing the spark plug's heat dissipation rate and further lowering its operating temperature, preventing pre-ignition knocking due to overheating. Reducing the volume of the heat chamber and the heat-receiving area of ​​the insulator skirt also reduces the heat absorbed by the spark plug during operation, further lowering its operating temperature. Finally, the vent hole on the annular side electrode allows exhaust gases from the heat chamber to escape, resulting in better spark plug performance.

[0037] In the embodiments, "multiple" refers to "two or more". The above embodiments are for illustrative purposes only and are not intended to limit the present invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also fall within the protection scope of the present invention, which should be defined by the claims.

Claims

1. A spark plug for a clean energy fuel engine, comprising a rod-shaped center electrode extending along an axial direction; an insulator having an axially extending bore and holding the center electrode within the bore, the center electrode being disposed at a front end of the insulator; a metal housing surrounding and holding the insulator in the circumferential direction, the rear end of the insulator extending out of the metal housing along the axial direction; and a side electrode, characterized in that: The side electrode is annular, and an annular mounting groove is provided on the inner circumferential surface of the front end of the metal housing. The annular side electrode is installed in the annular mounting groove. The front end face of the annular side electrode is flush with the front end face of the metal housing or the front end face of the annular side electrode is exposed on the front end face of the metal housing. Let A be the distance between the front end face of the annular side electrode and the front end face of the metal housing. Then 0mm < A ≤ 2mm. The front end of the center electrode extends into the center hole of the annular side electrode, and a spark gap H is left between the outer circumferential surface of the front end of the center electrode and the inner circumferential surface of the center hole of the annular side electrode.

2. The spark plug for a clean energy fuel engine according to claim 1, characterized in that: The insulator near the front end of the insulator contacts the inner circumferential surface of the metal shell through a washer. The insulator between the washer and the front end face of the insulator is the skirt of the insulator. The length of the skirt is set as skirt length B, then 3mm ≤ skirt length B ≤ 7mm.

3. The spark plug for a clean energy fuel engine according to claim 2, characterized in that: The space enclosed by the gasket, the skirt of the insulator, the inner circumferential surface of the metal shell, and the annular side electrode constitutes a heat storage chamber, the volume of which is defined as V; the volume V of the heat storage chamber is defined as V≤25mm. 3 .

4. The spark plug for a clean energy fuel engine according to claim 3, characterized in that: If the distance between the front end face of the insulator skirt and the rear end face of the annular side electrode is set as D, then the distance D ≤ 0.5 mm.

5. The spark plug for a clean energy fuel engine according to claim 3, characterized in that: The outer peripheral surface of the skirt of the insulator is parallel to the inner peripheral surface of the metal shell.

6. The spark plug for a clean energy fuel engine according to claim 5, characterized in that: If the distance between the outer circumferential surface of the skirt of the insulator and the inner circumferential surface of the metal shell is defined as H, then H≤0.1mm.

7. The spark plug for a clean energy fuel engine according to any one of claims 3 to 6, characterized in that: An exhaust port is provided on the annular side electrode, and the hot chamber of the spark plug communicates with the outside through the exhaust port.

8. The spark plug for a clean energy fuel engine according to claim 7, characterized in that: Let the area of ​​the annular end face of the annular side electrode be S1, and the area of ​​the exhaust port be S2, then S2 / S1≥6%.

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