Ignition plug assembly and hydrogen engine

Abstract

To attach an ignition plug assembly to a cylinder head without performing special processing to the cylinder head.SOLUTION: An ignition plug assembly is attached to a cylinder head having a plug hole communicating with a combustion chamber. The ignition plug assembly includes: a plug pipe which includes a base end part, a tip part opposite to the base end part, and a flange part provided between the base end part and the tip part and may be inserted into the plug hole and in which the tip part is butted with the cylinder head when the plug pipe is inserted into the plug hole; and an ignition plug disposed in the plug pipe. The flange part has a pressing surface which receives a force pressing the plug pipe to the combustion chamber side.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a spark plug assembly and a hydrogen engine. [Background technology]

[0002] Hydrogen engines, which use hydrogen as fuel and burn it mixed with air, have been attracting attention as a zero-emission power source that does not emit harmful substances such as carbon dioxide. However, the huge cost required for the development of new hydrogen engines is a factor preventing their widespread use.

[0003] In order to reduce the development costs of hydrogen engines, attempts are being made to convert the cylinder heads of commonly used diesel engines into hydrogen engines. As a technology for converting a cylinder head for a diesel engine into an engine with a different combustion method, for example, the technology described in Patent Document 1 is known.

[0004] Patent Document 1 describes a method in which a plug pipe that houses an ignition plug is inserted into a space in which an injector for injecting diesel fuel is placed, and a screw provided at the tip of the plug pipe is screwed into a screw hole on the cylinder head side, thereby fixing the plug pipe to the cylinder head. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-130485 A Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, a screw provided at the tip of the plug pipe is screwed into a screw hole on the cylinder head side, but the cylinder head may not have a screw hole communicating with the combustion chamber. In this case, processing is required to form a screw hole in the cylinder head in order to screw the plug pipe into the cylinder head. However, such processing is time-consuming and causes a decrease in engine production efficiency.

[0007] SUMMARY OF THE DISCLOSURE In view of the above, an object of the present disclosure is to provide an ignition plug assembly that can be attached to a cylinder head without requiring special processing. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided an ignition plug assembly which is attached to a cylinder head having a plug hole communicating with a combustion chamber. The spark plug assembly comprises a plug pipe which is insertable into the plug hole and which includes a base end, a tip end opposite the base end, and a flange portion provided between the base end and the tip end, the tip end of which abuts against the cylinder head when the plug pipe is inserted into the plug hole, and an ignition plug disposed within the plug pipe, and the flange portion has a pressing surface which receives a force pressing the plug pipe towards the combustion chamber.

[0009] With the tip of the plug pipe abutting against the cylinder head, the plug pipe receives a pressing force from the pressing surface of the flange, which presses the plug pipe against the cylinder head and fixes it in the plug hole. Therefore, with this spark plug assembly, the spark plug assembly can be attached to the cylinder head without any special processing being performed on the cylinder head.

[0010] The spark plug assembly may further include a fixing device that fixes the plug pipe to the cylinder head by pressing the pressing surface against the combustion chamber. By fixing the plug pipe to the cylinder head with this fixing device, the spark plug assembly can be attached to the cylinder head without special processing of the cylinder head.

[0011] The fixing device may include a clamp member that clamps the plug pipe between the flange portion and the base end portion, and a fastening member that is fastened to the cylinder head, and the clamp member may apply a pressing force toward the combustion chamber to a pressing surface when the fastening member is fastened to the cylinder head. By applying a pressing force toward the combustion chamber from the clamp member to the pressing surface, the plug pipe can be pressed against the cylinder head and fixed in the plug hole.

[0012] The plug pipe may have an internal thread on its inner surface, and the spark plug may have an external thread that screws into the internal thread. The spark plug is fixed to the plug pipe by screwing the external thread of the spark plug into the internal thread of the plug pipe.

[0013] The cylinder head may have a guide pipe that defines a plug hole and provides an abutment surface against which the tip of the plug pipe abuts, and the spark plug assembly may further include a first seal member disposed between the tip and the abutment surface. By disposing the first seal member between the tip and the abutment surface, the gap between the plug pipe and the guide pipe is sealed, and it is possible to prevent combustible gas from entering the gap from the combustion chamber.

[0014] The plug pipe may have a stepped surface providing a step on an inner surface of the plug pipe, and the spark plug assembly may further include a second seal member disposed between the spark plug and the stepped surface. By disposing the second seal member between the spark plug and the stepped surface, the gap between the spark plug and the plug pipe is sealed, and it is possible to prevent combustion gas in the combustion chamber from entering the gap.

[0015] The first seal member and the second seal member may be made of copper or aluminum. Since copper and aluminum are relatively soft metals, by making the first seal member and the second seal member from copper or aluminum, high sealing performance can be achieved. Furthermore, by making the first seal member and the second seal member from a conductive material, the spark plug is electrically grounded to the cylinder head via the first seal member and the second seal member. By grounding the spark plug, the spark plug can be operated stably.

[0016] The outer diameter of the plug pipe may be gradually reduced toward the tip end thereof. In this case, even if the inner diameter of the plug hole is gradually reduced toward the combustion chamber, the plug pipe can be inserted deep into the plug hole.

[0017] A hydrogen engine according to one aspect of the present invention comprises a cylinder that defines a combustion chamber, a piston that reciprocates within the cylinder, a cylinder head having an intake port for intake, an exhaust port for exhaust, and a plug hole that communicates with the combustion chamber, a hydrogen injector that adds hydrogen fuel to the intake air, and a spark plug assembly that ignites combustible gas containing hydrogen fuel, the ignition plug assembly being a plug pipe that is inserted into the plug hole and includes a base end, a tip end opposite the base end, and a flange portion provided between the base end and the tip end, the tip end being abutted against the cylinder head, and an ignition plug disposed within the plug pipe, the flange portion having a pressing surface that receives a force pressing the plug pipe towards the combustion chamber. Effect of the Invention

[0018] According to the present disclosure, the spark plug assembly can be attached to the cylinder head without special processing of the cylinder head. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is a side view of an ignition plug assembly according to one embodiment. [Diagram 2] FIG. 2 is a partial cross-sectional view of the plug pipe taken along the axial direction. [Diagram 3] 2. FIG. 3(a) is a cross-sectional view taken along line AA in FIG. 2, and FIG. 3(b) is a cross-sectional view taken along line BB in FIG. [Figure 4] FIG. [Diagram 5] FIG. 2 is a partial cross-sectional view showing an ignition plug assembly mounted on a cylinder head. [Figure 6] FIG. 1 is a schematic diagram of a hydrogen engine having an ignition plug assembly. [Figure 7] FIG. 11 is a partial cross-sectional view showing a modified example of the plug pipe. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions are omitted. The drawings may be partially simplified or exaggerated for ease of understanding, and the dimensional ratios, angles, etc. are not limited to those shown in the drawings.

[0021] FIG. 1 is a side view of an ignition plug assembly 1 according to one embodiment. The ignition plug assembly 1 is used to convert a cylinder head 50 for a diesel engine to a hydrogen engine. As described below, the cylinder head 50 has a space for installing an injector that injects diesel fuel. When the cylinder head 50 is converted to a hydrogen engine, the injector for diesel fuel becomes unnecessary. The ignition plug assembly 1 is installed in the space in place of the injector, and is used to ignite hydrogen fuel mixed with air.

[0022] As shown in Fig. 1, the spark plug assembly 1 includes a plug pipe 2, an ignition plug 3, and a fixing device 4. The plug pipe 2 is a hollow cylinder that includes a base end 11 and a tip end 12 and extends along an axis Z between the base end 11 and the tip end 12. The plug pipe 2 is a metallic cylinder, and is made of, for example, austenitic stainless steel that is resistant to hydrogen embrittlement. Examples of austenitic stainless steel that is resistant to hydrogen embrittlement include SUS304, SUS316, and SUS316L.

[0023] Fig. 2 is a partial cross-sectional view of the plug pipe 2 taken along the axis Z. As shown in Fig. 2, an internal space 2s for accommodating the ignition plug 3 is formed inside the plug pipe 2. The internal space 2s extends in a direction along the axis Z (hereinafter referred to as the "axial direction"). In the following description, the direction from the base end 11 to the tip end 12 in the axial direction may be referred to as the "downward" direction, and the direction from the tip end 12 to the base end 11 may be referred to as the "upward" direction.

[0024] As shown in FIG. 2, the plug pipe 2 includes a first flange portion 13 and a second flange portion 14. The first flange portion 13 is disposed between the base end portion 11 and the tip end portion 12 in the axial direction, and protrudes radially (perpendicular to the axis Z) outward from the outer surface of the main body portion 2a of the plug pipe 2. The second flange portion 14 is disposed between the base end portion 11 and the first flange portion 13 in the axial direction, and protrudes radially (perpendicular to the axis Z) outward from the outer surface of the main body portion 2a of the plug pipe 2. The first flange portion 13 and the second flange portion 14 are disposed with a gap therebetween in the axial direction. Therefore, a fitting portion 16 having an outer diameter smaller than the radial width of the first flange portion 13 and the second flange portion 14 is formed between the first flange portion 13 and the second flange portion 14.

[0025] Fig. 3(a) is a cross-sectional view taken along line AA in Fig. 2, and Fig. 3(b) is a cross-sectional view taken along line BB in Fig. 2. As shown in Fig. 3(a), the first flange portion 13 has a generally rectangular contour when viewed from the axial direction. The first flange portion 13 has an upper surface 13a facing upward and a lower surface 13b facing downward. The upper surface 13a and the lower surface 13b are surfaces perpendicular to the axis Z. As will be described later, the upper surface 13a of the first flange portion 13 forms a pressing surface that receives a force pressing the plug pipe 2 toward the combustion chamber.

[0026] As shown in Fig. 3(b), the second flange portion 14 has a circular contour when viewed from the axial direction. The second flange portion 14 has an upper surface 14a facing upward and a lower surface 14b facing downward. The upper surface 14a and the lower surface 14b are surfaces perpendicular to the axis Z. The maximum width of the first flange portion 13 in the direction perpendicular to the axial direction is larger than the outer diameter of the second flange portion 14.

[0027] 2, the outer diameter of the plug pipe 2 may be gradually reduced toward the tip portion 12. The inner diameter of the plug pipe 2 is gradually reduced toward the tip portion 12 in accordance with the outer diameter. In particular, the inner surface of the tip portion 12 of the plug pipe 2 has the smallest inner diameter among the inner surfaces of the plug pipe 2. A female thread portion 15 for fixing the spark plug 3 is formed on the inner surface of the tip portion 12.

[0028] The inner diameter of the plug pipe 2 is reduced in stages, so that a stepped surface 11a is formed on the inner surface of the plug pipe 2. In other words, the stepped surface 11a provides a step on the inner surface of the plug pipe 2. The stepped surface 11a is an upwardly facing annular flat surface, and is connected to the inner surface of the tip portion 12. The stepped surface 11a supports a metal fitting 24 of the spark plug 3.

[0029] The spark plug 3 is disposed in the internal space 2s of the plug pipe 2. As shown in Fig. 2, the spark plug 3 has a terminal 21, a center electrode 22, a ground electrode 23, a metal fitting 24, and a male thread portion 25. The terminal 21 is provided at the upper end of the spark plug 3, and supplies power received from an external power source to the center electrode 22. The ground electrode 23 is provided at the lower end of the spark plug 3, and is disposed outside the plug pipe 2. When power is supplied to the terminal 21, a high voltage current is discharged between the center electrode 22 and the ground electrode 23, generating a spark in the combustion chamber 60. The spark ignites combustible gas in the combustion chamber 60.

[0030] The metal fitting 24 is provided between the terminal 21 and the ground electrode 23 in the axial direction, and is provided along the outer periphery of the spark plug 3. The metal fitting 24 is electrically connected to the ground electrode 23. The male threaded portion 25 is provided between the ground electrode 23 and the metal fitting 24 in the axial direction, and can be screwed into the female threaded portion 15. When the male threaded portion 25 is screwed into the female threaded portion 15, the spark plug 3 is fixed to the plug pipe 2.

[0031] The spark plug assembly 1 further includes a first seal member 41 and a second seal member 42. The first seal member 41 is a packing such as an O-ring, and is provided so as to surround the spark plug 3 outside (below) the plug pipe 2. The second seal member 42 is a packing such as an O-ring, and is disposed between the metal fitting 24 of the spark plug 3 and the stepped surface 11a of the plug pipe 2, and is provided so as to surround the spark plug 3.

[0032] The first seal member 41 and the second seal member 42 are made of a conductive metal material such as copper or aluminum. Since copper and aluminum are relatively soft metal materials, high sealing performance is achieved by making the first seal member 41 and the second seal member 42 from copper or aluminum.

[0033] The fixing device 4 has a function of fixing the plug pipe 2 to the cylinder head 50. The fixing device 4 is originally a device used for fixing an injector for diesel fuel. Therefore, as will be described later, the cylinder head 50 is formed with a screw hole 50a for fastening the fixing device 4 (see FIG. 5). The spark plug assembly 1 is designed so that the plug pipe 2 can be fixed to the cylinder head 50 by using the fixing device 4 for a diesel engine.

[0034] As shown in FIG. 1, the fixing device 4 includes a clamp member 31 and a fastening member 32. FIG. 4 is a top view of the clamp member 31. As shown in FIG. 4, the clamp member 31 has a base 33 having a through hole and a pair of arms 34 extending in a bifurcated manner from the base 33. The base 33 and the pair of arms 34 are integrally formed of a metal material. As shown in FIG. 1, the pair of arms 34 are fitted into the fitting portion 16 so as to sandwich the plug pipe 2 between the first flange portion 13 and the second flange portion 14 from the radial direction. Typically, the pair of arms 34 are arranged in the fitting portion 16 so as to face each other in the long side direction of the first flange portion 13.

[0035] The fastening member 32 has a head 35 and a shaft 36 connected to the head 35 and extending in the axial direction. Typically, the fastening member 32 is a hexagonal bolt. The shaft 36 is inserted into a through hole formed in the base 33 of the clamp member 31. The through hole has a diameter smaller than the maximum width of the head 35 and larger than the diameter of the shaft 36. A male thread 36a is formed at the tip of the shaft 36 to be fastened to a screw hole 50a of the cylinder head 50.

[0036] As described below, when the fastening member 32 is fastened to the cylinder head, the clamp member 31 is pressed downward together with the head 35, and the upper surface 13a of the first flange portion 13 is pressed toward the combustion chamber 60 side.

[0037] Figure 5 is a partial cross-sectional view showing the spark plug assembly 1 attached to a cylinder head 50. The cylinder head 50 shown in Figure 5 is a diesel engine cylinder head converted for use in a hydrogen engine. The cylinder head 50 is a structure that defines the combustion chamber 60 from above, and has a guide pipe 52 that defines a spark plug hole 51, and a water jacket 53 through which cooling water flows.

[0038] The plug hole 51 is originally a space for accommodating an injector for diesel fuel, and communicates with the combustion chamber 60. The plug hole 51 has, for example, a circular cross-sectional shape, and the inner diameter of the plug hole 51 is gradually reduced toward the combustion chamber 60. By gradually reducing the inner diameter of the plug hole 51, an abutment surface 52a is formed on the inner surface of the guide pipe 52. The abutment surface 52a is an annular flat surface facing upward, and has an inner diameter smaller than the outer diameter of the tip portion 12. Therefore, when the plug pipe 2 is inserted into the plug hole 51, the tip portion 12 of the plug pipe 2 abuts against the abutment surface 52a. The first seal member 41 described above is disposed between the tip portion 12 of the plug pipe 2 and the abutment surface 52a.

[0039] The cylinder head 50 has a screw hole 50a for fastening the fastening member 32 of the fixing device 4. The screw hole 50a is formed at a position adjacent to the spark plug hole 51 in a top view.

[0040] Next, a procedure for attaching the spark plug assembly 1 to the cylinder head 50 will be described. When attaching the spark plug assembly 1 to the cylinder head 50, first, the spark plug 3 is inserted into the plug pipe 2, and the male threaded portion 25 is screwed into the female threaded portion 15 with the second seal member 42 interposed between the metal fitting 24 of the spark plug 3 and the step surface 11a, thereby fastening the spark plug 3 to the plug pipe 2. At this time, the second seal member 42 is crushed between the spark plug 3 and the step surface 11a, and the gap between the plug pipe 2 and the spark plug 3 is sealed. As a result, the intrusion of combustible gas from the combustion chamber 60 into the internal space 2s of the plug pipe 2 is prevented.

[0041] Next, the first seal member 41 is attached to the tip portion of the spark plug 3, and the plug pipe 2 is inserted into the plug hole 51. At this time, the pair of arms 34 of the clamp member 31 are fitted into the fitting portion 16 of the plug pipe 2 above the first flange portion 13, more specifically, between the first flange portion 13 and the second flange portion 14. When the plug pipe 2 is inserted deep into the plug hole 51, the tip portion 12 of the plug pipe 2 abuts against the abutment surface 52a of the guide pipe 52, as shown in FIG. 5. This positions the ground electrode 23 of the spark plug 3 in the combustion chamber 60.

[0042] Next, the male thread portion 36a of the fastening member 32 is screwed into the threaded hole 50a of the cylinder head 50. This presses down the clamp member 31 connected to the fastening member 32, and a pressing force F directed downward (towards the combustion chamber 60) is applied to the upper surface 13a of the first flange portion 13. This pressing force F presses the plug pipe 2 against the cylinder head 50 and fixes it. This pressing force F also crushes the first seal member 41 between the tip end 12 of the plug pipe 2 and the abutment surface 52a. As a result, the gap between the plug pipe 2 and the guide pipe 52 is sealed, and the intrusion of combustible gas from the combustion chamber 60 into the gap is prevented.

[0043] As described above, in the spark plug assembly 1, when the fastening member 32 of the fixing device 4 is fastened to the cylinder head 50, the clamp member 31 is pressed down and a pressing force toward the combustion chamber 60 is applied to the upper surface 13a of the first flange portion 13. This pressing force presses the plug pipe 2 against the cylinder head 50, so that the plug pipe 2 is fixed together with the spark plug 3 in the plug hole 51 of the cylinder head 50. By fixing the plug pipe 2 by pressing the first flange portion 13, the spark plug assembly 1 can be attached to the cylinder head 50 without special processing such as forming a screw hole in the cylinder head. Furthermore, the adoption of such a structure makes it easier to attach and detach the spark plug assembly 1, which also contributes to improved maintainability.

[0044] Next, a cylinder head cover 55 that covers the cylinder head 50 is attached above the cylinder head 50. For example, as shown in FIG. 5 , the cylinder head cover 55 is provided so as to surround the outer periphery of the second flange portion 14 via a packing 56. As a result, the base end portion 11 of the plug pipe 2 is disposed outside (above) the cylinder head cover 55. Note that the cylinder head cover 55 may be disposed above the base end portion 11 of the plug pipe 2.

[0045] Next, a hydrogen engine 100 equipped with the spark plug assembly 1 will be described. Fig. 6 is a diagram showing a schematic diagram of the hydrogen engine 100 according to one embodiment. The hydrogen engine 100 is equipped with the spark plug assembly 1, a cylinder block 40, a cylinder head 50, and a hydrogen injector 62. The cylinder block 40 is equipped with a cylinder 71 that defines a combustion chamber 60.

[0046] A piston 72 is provided in the cylinder 71. The piston 72 is connected to a crank 74 via a connecting rod 73. When fuel is combusted in the combustion chamber 60, the piston 72 reciprocates within the cylinder 71, causing the crank 74 to rotate.

[0047] The cylinder head 50 has a spark plug hole 51, an intake port 75, and an exhaust port 76. The above-mentioned ignition plug assembly 1 is disposed in the spark plug hole 51. The intake port 75 opens to the combustion chamber 60 and supplies intake air (combustible gas) containing hydrogen fuel supplied through an intake passage 78 to the combustion chamber. The intake port 75 is provided with an intake valve 81 that controls the supply of intake air to the combustion chamber 60. The intake valve 81 is opened and closed by controlling the drive of a camshaft 83.

[0048] The exhaust port 76 opens into the combustion chamber 60, and discharges exhaust gas generated in the combustion chamber 60 by combustion of combustible gas into an exhaust passage 79. The exhaust port 76 is provided with an exhaust valve 82 that controls the discharge of exhaust gas from the combustion chamber 60. The exhaust valve 82 is opened and closed by controlling the drive of a camshaft 84.

[0049] The hydrogen injector 62 injects hydrogen fuel into the intake passage 78 to add hydrogen fuel to the intake air. Combustible gas containing hydrogen fuel is supplied to the combustion chamber 60 via the intake port 75. The spark plug assembly 1 activates the spark plug 3 to ignite the combustible gas in the combustion chamber 60. Exhaust gas generated by the combustion of the combustible gas is discharged from the exhaust port 76.

[0050] Although the spark plug assembly 1 according to various embodiments has been described above, the present invention is not limited to the above-described embodiments and various modifications can be made without departing from the spirit and scope of the invention. The above-described various embodiments can be combined together without causing any inconsistency.

[0051] For example, as long as the plug pipe 2 can be pressed toward the combustion chamber 60, the spark plug assembly 1 does not necessarily have to include the fixing device 4. For example, the plug pipe 2 may be fixed to the cylinder head 50 by pressing the upper surface 14a of the second flange portion 14 downward from above the cylinder head cover 55 by fastening a bolt or the like to press the plug pipe 2 against the cylinder head 50. Furthermore, the outer diameter of the plug pipe 2 may be constant in the axial direction except for the positions where the first flange portion 13 and the second flange portion 14 are formed. The spark plug assembly 1 may also be applied to engines that use gases other than hydrogen gas as fuel.

[0052] In one embodiment, the plug pipe 2 may not have the second flange portion 14. For example, as shown in Fig. 7, the plug pipe 2 may not include the second flange portion 14, and the base end portion 11 of the plug pipe 2 may be disposed in the same plane as the upper surface 13a of the first flange portion 13. In this embodiment, the first flange portion 13 is disposed below the cylinder head cover 55, and the upper surface 13a of the first flange portion 13 receives a pressing force from the fixing device 4 toward the combustion chamber 60. As a result, the plug pipe 2 is pressed against the cylinder head 50 and fixed.

[0053] The present disclosure includes the following: [1] A spark plug assembly to be attached to a cylinder head having a plug hole communicating with a combustion chamber, a plug pipe that can be inserted into the plug hole, the plug pipe including a base end, a tip end opposite to the base end, and a flange portion; a spark plug disposed in the plug pipe; Equipped with the tip end is abutted against the cylinder head when the plug pipe is inserted into the plug hole, The flange portion has a pressing surface that receives a force pressing the plug pipe toward the combustion chamber.

[0054] [2] The spark plug assembly according to [1], further comprising a fixing device that presses the pressing surface toward the combustion chamber to fix the plug pipe to the cylinder head.

[0055] [3] The fixing device includes a clamp member disposed above the flange portion and a fastening member fastened to the cylinder head, The clamp member applies a pressing force toward the combustion chamber to the pressing surface when the fastening member is fastened to the cylinder head.

[0056] [4] The plug pipe has an inner surface provided with a female thread portion, The spark plug assembly according to any one of [1] to [3], wherein the spark plug is provided with a male thread portion that screws into the female thread portion.

[0057] [5] The cylinder head has a guide pipe that defines the plug hole and provides a contact surface against which the tip end of the plug pipe contacts, The spark plug assembly according to any one of [1] to [4], further comprising a first seal member disposed between the tip portion and the abutment surface.

[0058] [6] The plug pipe has a stepped surface that provides a step on an inner surface of the plug pipe, The spark plug assembly according to [5], further comprising a second seal member disposed between the spark plug and the stepped surface.

[0059] [7] The spark plug assembly according to [6], wherein the first seal member and the second seal member are made of copper or aluminum.

[0060] [8] The spark plug assembly according to any one of [1] to [7], wherein an outer diameter of the plug pipe is gradually reduced toward the tip end.

[0061] [9] a cylinder defining a combustion chamber; A piston that reciprocates within the cylinder; a cylinder head having an intake port for intake, an exhaust port for exhaust, and a plug hole communicating with the combustion chamber; a hydrogen injector that adds hydrogen fuel to the intake air; a spark plug assembly for igniting the combustible gas containing the hydrogen fuel; Equipped with The spark plug assembly includes: a plug pipe inserted into the plug hole, the plug pipe including a base end, a tip end opposite to the base end, and a flange portion; a spark plug disposed in the plug pipe; Equipped with The tip end is abutted against the cylinder head within the plug hole, The flange portion has a pressing surface that receives a force pressing the plug pipe toward the combustion chamber. [Explanation of symbols]

[0062] Reference Signs List 1...spark plug assembly, 2...plug pipe, 3...spark plug, 4...fixing device, 11...base end, 11a...step surface, 12...tip end, 15...female threaded portion, 25...male threaded portion, 31...clamp member, 32...fastening member, 41...first sealing member, 42...second sealing member, 50...cylinder head, 51...spark plug hole, 52...guide pipe, 52a...butting surface, 60...combustion chamber, 62...hydrogen injector, 71...cylinder, 72...piston, 75...intake port, 76...exhaust port, 100...hydrogen engine, F...pressing force.

Claims

1. A spark plug assembly to be attached to a cylinder head having a plug hole communicating with a combustion chamber, a plug pipe that can be inserted into the plug hole, the plug pipe including a base end, a tip end opposite to the base end, and a flange portion; a spark plug disposed in the plug pipe; Equipped with the tip end is abutted against the cylinder head when the plug pipe is inserted into the plug hole, The flange portion has a pressing surface that receives a force pressing the plug pipe toward the combustion chamber.

2. 2. The spark plug assembly according to claim 1, further comprising a fastener for fastening said plug pipe to said cylinder head by pressing said pressing surface against said combustion chamber.

3. The fixing device includes a clamp member disposed above the flange portion and a fastening member fastened to the cylinder head, 3. The spark plug assembly according to claim 2, wherein the clamp member applies a pressing force toward the combustion chamber to the pressing surface when the fastening member is fastened to the cylinder head.

4. The plug pipe has an inner surface provided with a female thread portion, 2. The spark plug assembly of claim 1, wherein said spark plug is provided with a male threaded portion that screws into said female threaded portion.

5. the cylinder head has a guide pipe that defines the plug hole and provides a contact surface against which the tip end of the plug pipe contacts, 2. The spark plug assembly of claim 1 further comprising a first seal member disposed between said tip and said abutment face.

6. the plug pipe has a stepped surface providing a step on an inner surface of the plug pipe, 6. The spark plug assembly of claim 5, further comprising a second seal member disposed between the spark plug and the stepped surface.

7. 7. The spark plug assembly of claim 6, wherein said first seal member and said second seal member are constructed from copper or aluminum.

8. 2. The spark plug assembly according to claim 1, wherein an outer diameter of said plug pipe is gradually reduced toward said tip end.

9. A cylinder defining a combustion chamber; A piston that reciprocates within the cylinder; a cylinder head having an intake port for intake, an exhaust port for exhaust, and a plug hole communicating with the combustion chamber; a hydrogen injector that adds hydrogen fuel to the intake air; a spark plug assembly for igniting the combustible gas containing the hydrogen fuel; Equipped with The spark plug assembly includes: a plug pipe inserted into the plug hole, the plug pipe including a base end, a tip end opposite to the base end, and a flange portion; a spark plug disposed in the plug pipe; Equipped with The tip end is abutted against the cylinder head within the plug hole, The flange portion has a pressing surface that receives a force pressing the plug pipe toward the combustion chamber.

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