JP2007182808A - Guide tube and cylinder head having it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a guide tube 30 having a longitudinal one end side disposed to cover a spark plug mounting region in a cylinder head 1 of an internal combustion engine, having a longitudinal other end side disposed to connect with a plug insertion hole 2a provided in a cylinder head cover 2, serving as a guide when attaching a spark plug 15 to or detaching it from the cylinder head 1 and when attaching a direct ignition 20 to or detaching it from the spark plug 15 and facilitating attaching and detaching work of the direct ignition 20 with respect to the spark plug 15. <P>SOLUTION: A bulge 33 is provided in the longitudinal middle of the guide tube 30. The bulge 33 has a clearance space ensured inside for allowing radially-outward movement of a plug connection 24 of the direct ignition 20 when the direct ignition 20 is tilted in course of its attaching or detaching. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition system or a fuel injection system rod-like member (for example, a spark plug, a direct ignition, a plug cap, a direct injection injector, etc.) in an internal combustion engine used for an automobile, a motorcycle, an agricultural machine, a ship, etc. The guide tube is a guide. The present invention also relates to a cylinder head having the guide tube.

  In an internal combustion engine, mainly a gasoline engine or the like uses a spark plug to ignite and burn an air-fuel mixture supplied to each combustion chamber.

  In order to optimally control the ignition timing of the spark plug, a direct ignition system is used as is generally known (see, for example, Patent Document 1).

  Usually, the spark plug is attached to the cylinder head so that the ignition part is exposed in the combustion chamber, and a direct ignition is attached to the spark plug.

  Although direct ignition is generally known, a coil portion is provided in a cylindrical case, an igniter portion is provided at the upper end of the cylindrical case, and a plug coupling portion is provided at the lower end of the cylindrical case.

  Generally, the cylindrical case is formed of, for example, a relatively hard appropriate insulating synthetic resin or the like. The lower end of the cylindrical case, for example, an appropriate rubber or the like so as to cover the plug coupling portion. An elastic cover formed of an insulating material is provided.

  The plug joint is snap-fitted onto the spark plug terminal head, and the elastic cover hides the joint between the direct ignition plug joint and the spark plug terminal head from the outside. And is electrically insulated.

The spark plug and the direct ignition are covered with a guide tube. This guide tube isolates the spark plug and direct ignition from the valve mechanism arrangement space that surrounds the cylinder head and the cylinder head cover, and is used when the spark plug is attached to the cylinder head and when the direct ignition is attached to the spark plug. It is a guide. The guide tube generally has a cylindrical shape with a constant inner diameter in the longitudinal direction.
JP-A-5-280458

  In order to ensure the original guide function of the guide tube of the above-described conventional example, it is desirable that the inner diameter dimension is slightly larger than the outer diameter dimension of the direct ignition, but in the following situation, It is pointed out that the work of removing the direct ignition is cumbersome and time-consuming.

  Specifically, for example, a part related to the internal combustion engine is arranged above the cylinder head cover, particularly above the direct ignition, and this part may become an obstacle when the direct ignition is attached or detached.

  In such a case, when the direct ignition is separated from the spark plug and then taken out, it is necessary to prevent the direct ignition from interfering with the obstacle.

  For this purpose, for example, it is only necessary to avoid interference with an obstacle by tilting the posture while taking out a direct ignition.

  However, if the inner diameter dimension of the guide tube is set as close as possible to the outer diameter dimension of the direct ignition as in the conventional example above, when the direct ignition is removed from the guide tube, the posture of the direct ignition is changed. The tilt angle becomes small, and depending on the position of the obstacle, it becomes impossible to avoid direct ignition interference with the obstacle.

  In such a case, the direct ignition must be removed after the obstacle is removed, which takes time and effort. There is room for improvement here.

  An object of the present invention is to provide a guide tube and a cylinder head that make it easy to attach and detach a rod-shaped member of an ignition system or a fuel supply system.

  The present invention is a guide tube that serves as a guide when a rod-like member of an ignition system or a fuel supply system is detachably mounted on a cylinder head of an internal combustion engine with one end in the longitudinal direction exposed to a combustion chamber. One end side in the direction is attached so as to cover the rod-shaped member mounting area in the cylinder head, and the other end side in the longitudinal direction is attached so as to communicate with a through hole provided in the cylinder head cover. A relief space is provided for allowing the rod-like member to move radially outward on the distal end side in the mounting direction when the member is attached or detached.

  Examples of the ignition system or fuel injection system rod-shaped member include a spark plug, a direct ignition, a plug cap, and a direct injection injector.

  According to this configuration, for example, when removing the rod-shaped member from the cylinder head, it is necessary to tilt the posture while taking out the rod-shaped member from the other end side of the guide tube, for example, due to the presence of an obstacle on the rod-shaped member removal side. In some cases, the inclination angle of the rod-like member can be increased as much as possible.

  In the first place, if the guide tube is cylindrical, that is, has the same inner diameter over the entire length in the longitudinal direction, if the rod-shaped member is separated from the cylinder head and then tilted in the guide tube, the distal end edge of the rod-shaped member in the mounting direction will be the center of the guide tube. Since it is displaced radially outward from the side and abuts against the inner peripheral surface of the middle portion in the longitudinal direction of the guide tube, its inclination is limited.

  Therefore, if the inner diameter of the guide tube is made as large as possible and the distance between the inner circumferential surface and the tip end edge of the rod-shaped member in the mounting direction is increased, the tip end edge of the guide tube is attached as the rod-shaped member is tilted. The distance until it comes into contact with the inner peripheral surface of the guide tube is extended, and as a result, the inclination angle of the rod-shaped member can be increased.

  However, if the inner diameter of the cylindrical guide tube is increased, naturally, when the rod-shaped member is mounted on the cylinder head, a guide for aligning the rods cannot be provided, and the guide function inherent to the guide tube is reduced. Damaged.

  For this reason, providing a clearance space only in the middle of the guide tube in the longitudinal direction ensures the guide function of the guide tube when the rod-shaped member is mounted, and the inclination angle when removing the rod-shaped member is as much as possible. It is possible to make it bigger.

  Preferably, the inner diameter at the other end in the longitudinal direction is larger than the inner diameter at one end in the longitudinal direction, and in the middle of the longitudinal direction, the inner diameter swells outward in the radial direction so as to be larger than the one end side. A bulging portion is provided, and the escape space is secured on the inner diameter side of the bulging portion.

  As described above, in order to secure the escape space, the guide tube can be specified to have a shape having different diameters in the longitudinal direction.

  Preferably, the bulging portion has a barrel shape by maximizing the inner diameter at the center in the longitudinal direction and gradually reducing the diameter from the maximum inner diameter portion toward both sides in the longitudinal direction.

  According to this configuration, when attaching and detaching the rod-shaped member, when it is necessary to tilt the posture, as in the initial stage of removal of the rod-shaped member or the late stage of attachment, etc., even in a situation where the projection allowance of the rod-shaped member from the guide tube is small, The tilt angle can be increased as much as possible. Thereby, the attaching / detaching operation of the rod-like member can be performed easily and quickly.

  Preferably, the shape of the half when the bulging portion is made a cross-section along the longitudinal direction thereof is a movement trajectory drawn by the tip end edge of the rod-shaped member in the process of tilting the posture while taking out the rod-shaped member. Correspondingly, the curve is curved in the longitudinal direction.

  According to this structure, when attaching and detaching a rod-shaped member, the operation | movement which inclines the attitude | position can be performed smoothly. Thereby, the attaching / detaching operation of the rod-like member can be performed easily and quickly.

  The present invention is a guide tube that serves as a guide when a rod-like member of an ignition system or a fuel supply system is detachably mounted on a cylinder head of an internal combustion engine with one end in the longitudinal direction exposed to a combustion chamber. One end in the direction is attached so as to cover the rod-shaped member mounting area in the cylinder head, and the other end in the longitudinal direction is attached so as to communicate with a through hole provided in the cylinder head cover. A bulging portion that bulges outward is provided.

  The present invention covers a spark plug that burns an air-fuel mixture in a combustion chamber of an internal combustion engine, a direct ignition that is removably attached to the spark plug and applies an ignition voltage, and the spark plug and the direct ignition. A cylinder head including a guide tube that is provided so as to surround and serves as a guide when the spark plug is attached / detached and when the direct ignition is attached / detached, wherein the guide tube is configured as described above. .

  According to this configuration, since the guide tube having the above-described characteristics is used, when removing the direct ignition, the tilt angle is increased as much as possible in the case of performing the operation of tilting the posture while taking it out from the guide tube. It becomes possible.

  As a result, for example, even when there is an obstacle on the removal side of the direct ignition, it becomes possible to remove the direct ignition while avoiding the obstacle, and it is not necessary to remove the obstacle in advance. .

  According to the guide tube and the cylinder head of the present invention, it becomes easy to attach and detach the rod-shaped member of the ignition system or the fuel injection system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. One embodiment of the present invention is shown in FIGS.

  In this embodiment, an example will be given in which the present invention is applied to an internal combustion engine (for example, a gasoline engine) of DOHC type and having two intake valves and two exhaust valves per cylinder. The number of cylinders and the cylinder layout of the internal combustion engine are not particularly limited, but only one cylinder is illustrated for easy understanding.

  As shown in FIGS. 1 and 2, an intake camshaft 3 and an exhaust camshaft 4 are arranged in a space between the cylinder head 1 and the cylinder head cover 2. The intake camshaft 3 is opened into the combustion chamber 11 by displacing two pairs of intake valves 5 and the exhaust camshaft 4 by displacing two pairs of exhaust valves 6 upward or downward, respectively. The intake port (not shown) and the exhaust port (not shown) are closed or opened.

  The cam lobes 3a and 4a of the camshafts 3 and 4 are in contact with the valves 5 and 6 through rocker arms 7 and 8, respectively. The valves 5 and 6 are closed by valve springs 9 and 10, respectively. It has come to be energized.

  As shown in FIG. 2, a spark plug 15 is attached to the cylinder head 1 at the center position of each combustion chamber 11. As shown in FIG. 1, the spark plug 15 is disposed in a state where the ignition portion 15 a is exposed in the combustion chamber 11.

  In the internal combustion engine of this embodiment, in order to optimally control the ignition timing of the spark plug 15, a generally known direct ignition system is used.

  Specifically, a direct ignition 20 is connected to the spark plug 15.

  The direct ignition 20 is generally known. For example, as shown in FIGS. 1 and 3, a coil part 22 is provided in a cylindrical case 21, an igniter part 23 is provided at the upper end of the cylindrical case 21, and a cylindrical part is provided. A plug coupling portion 24 is provided at the lower end of the case 21.

  As shown in FIG. 1, the plug coupling portion 24 is structured to be externally fitted in a snap-fit state to the terminal head 15 b of the spark plug 15, and is a small diameter cylinder integrally formed at the lower end of the cylindrical case 21. It is comprised by the part 24a and the coil spring 24b arrange | positioned in this small diameter cylindrical part 24a.

  The cylindrical case 21 is formed of a relatively hard appropriate insulating synthetic resin or the like. An elastic cover 25 is integrally attached to the lower end of the cylindrical case 21 so as to cover the small diameter cylindrical portion 24a. . The elastic cover 25 is formed of, for example, a relatively flexible appropriate insulating rubber or the like, and electrically conceals the connection portion from the outside in a state where the plug connection portion 24 and the terminal head 15b of the spark plug 15 are connected. It is to be insulated.

  The spark plug 15 and the direct ignition 20 are covered with a guide tube 30.

  The guide tube 30 isolates the spark plug 15 and the direct ignition 20 from the valve mechanism disposition space surrounding the cylinder head 1 and the cylinder head cover 2, and also when the spark plug 15 is attached to the cylinder head 1 and the direct ignition 20. This is used as a guide for facilitating centering when attaching to the spark plug 15.

  Here, in order to increase the degree of freedom of posture change when the direct ignition 20 is attached / detached, the guide tube 30 has a shape with a different diameter in the longitudinal direction, which will be described in detail below.

  Specifically, the guide tube 30 is formed of, for example, an appropriate insulating synthetic resin, an appropriate insulating rubber, or the like, or other materials having excellent insulating properties and oil resistance.

  The lower end side, that is, one end side 31 in the longitudinal direction of the guide tube 30 is arranged so as to cover the mounting region of the spark plug 15 in the cylinder head 1, and the upper end side, that is, the other end side 32 in the longitudinal direction of the guide tube 30 is It arrange | positions so that it may connect with the plug insertion / extraction hole (through-hole) 2a provided in the cylinder head cover 2. FIG.

  The other end side 32 of the guide tube 30 is disposed below the plug insertion / extraction hole 2a of the cylinder head cover 2, and the opening on the other end side 32 of the guide tube 30 and the plug insertion / extraction hole 2a of the cylinder head cover 2 are sealed. It is designed to be connected through a communication.

  The seal 12 is attached in a state of being positioned in the plug insertion / extraction hole 2 a of the cylinder head cover 2, and the skirt portion 12 a is in close contact with the other end 32 opening of the guide tube 30.

  That is, the seal 12 prevents the lubricating oil in the valve mechanism arrangement space formed by the cylinder head 1 and the cylinder head cover 2 from entering the guide tube 30, and external water, dust, etc. in the guide tube 30. This prevents the foreign matter from entering the valve mechanism arrangement space even when the foreign matter enters.

  The inner diameter dimension of the one end side 31 of the guide tube 30 is to ensure a guide function such as easy alignment when the spark plug 15 is attached to and detached from the cylinder head 1 and when the direct ignition 20 is attached to the spark plug 15. The outer diameter of the direct ignition 20 is slightly larger.

  Further, the inner diameter dimension of the other end side 32 of the guide tube 30 is appropriately larger than the inner diameter dimension of the one end side 31, and the bulging portion 33 swells radially outward in the longitudinal direction of the guide tube 30. Is provided.

  The bulging portion 33 has a maximum inner diameter dimension in the center in the longitudinal direction, and has a barrel shape by being gradually reduced in diameter from the maximum inner diameter portion toward both sides in the longitudinal direction. The inner diameter dimension of the maximum inner diameter portion of the bulging portion 33 is set to be larger than both end sides 31 and 32 in the longitudinal direction. The facing space between the bulging portion 33 and the direct ignition 20 is the escape space described in the claims.

  By the way, as shown in FIGS. 1 and 2, two intake valves 5, 5 and two exhaust valves 6, 6 are arranged vertically and horizontally in each cylinder of the internal combustion engine, and a spark plug 15 is provided at the center thereof. In general, the valves 5 and 6 are slightly inclined with respect to the center of each cylinder, and the area inside the frame surrounded by the stem end side of each valve 5 and 6 is normally set to each valve 5 and 6. The guide tube 30 provided with the bulging portion 33 in the middle in the longitudinal direction as described above is disposed in the frame surrounded by the valves 5 and 6 because of the relationship larger than the area in the frame surrounded on the umbrella side. It is possible.

  In this way, even in the guide tube 30 provided with the bulging portion 33 in the middle in the longitudinal direction, the valves 5 and 6, the rocker arms 7 and 8, and the coil springs 9 and 10 are arranged apart from each other. Since this is not necessary, the compactness of the cylinder head 1 is not impaired.

  Next, a procedure for attaching / detaching the direct ignition 20 to / from the spark plug 15 and a behavior of the direct ignition 20 at that time will be described with reference to FIGS.

  Here, for example, it is assumed that a part 40 related to the internal combustion engine is disposed above the cylinder head cover 2 and particularly above the direct ignition 20, and this part 40 becomes an obstacle when the direct ignition 20 is attached or detached. I will explain.

  In such a case, first, the direct ignition 20 is separated from the spark plug 15 as shown in FIG. At this time, the direct ignition 20 is simply pulled straight, but the direct ignition 20 is slightly removed so as not to contact the part 40 as the obstacle.

  Thereafter, when the direct ignition 20 is pulled straight to take out the direct ignition 20 from the guide tube 30, the direct ignition 20 abuts on the part 40 as the obstacle. Therefore, as shown in FIG. 5, the posture of the direct ignition 20 is predetermined. It is necessary to tilt the angle θ.

  In this way, avoiding interference with the part 40 as an obstacle, the posture inclination angle θ is gradually increased while gradually taking out the direct ignition 20 as shown in FIGS. Note that the inclination angle θ of the direct ignition 20 increases as the flow shifts from FIG. 5 to FIG. 7, and finally the direct ignition 20 can be completely taken out as shown in FIG. 3.

  By the way, when the direct ignition 20 is attached to the spark plug 15, the above operation may be reversed, and the description thereof is omitted.

  As described above, in this embodiment, in order to increase the inclination angle of the direct ignition 20 as much as possible in the series of removal operations described above, the upper end side of the guide tube 30, that is, the other end 32 in the longitudinal direction. The inner diameter dimension is set to be as large as possible than the outer diameter dimension of the direct ignition 20, and the bulging portion 33 is provided in the middle of the guide tube 30 in the longitudinal direction.

  As a result, as shown in FIGS. 5 to 7, it is possible to increase the distance until the end edge of the plug coupling portion 24 contacts the inner peripheral surface of the guide tube 30 when the direct ignition 20 is tilted. . Therefore, when the direct ignition 20 is taken out from the guide tube 30, the inclination angle of the direct ignition 20 can be increased as much as possible, and the direct ignition 20 can be prevented from interfering with the component 40 as an obstacle. It can be taken out.

  Therefore, there is no need to bother removing the part 40 as the obstacle as in the conventional example, so that the direct ignition 20 can be easily and quickly removed.

  By the way, the guide tube 30 of this embodiment is set so that the inner diameter dimension of only the lower end side thereof, that is, the one longitudinal end side 31 is as close as possible to the outer diameter dimension of the direct ignition 20. A guide function for mounting the spark plug 15 to the spark plug 15 and a guide function for mounting the direct ignition 20 to the spark plug 15 can be secured.

  As described above, by providing the bulging portion 33 only in the middle of the guide tube 30 in the longitudinal direction, the inclination angle when attaching and detaching the direct ignition 20 is as much as possible after securing the original guide function of the guide tube 30. It is possible to make it bigger.

  Considering such an operation of attaching and detaching the direct ignition 20, the shape of the bulging portion 33 of the guide tube 30 is, for example, a barrel shape as described above. The shape will be described in detail below.

  That is, in the state where the guide tube 30 is cross-sectioned along its longitudinal direction, the shape of the half of the bulging portion 33 is, as shown in FIG. 8, for example, a direct ignition to avoid a part 40 as an obstacle. In the process of tilting 20 while taking out, it is preferable to have a curved shape curved in the longitudinal direction corresponding to the movement locus X drawn by the edge of the plug coupling portion 24 located on the front end side of the direct ignition 20 in the mounting direction.

  Actually, the elastic cover 25 of the direct ignition 20 abuts on the inner peripheral surface of the bulging portion 33 of the guide tube 30. However, since the elastic cover 25 is bent, the end of the plug coupling portion 24 of the direct ignition 20 is used. It has been described that the edge substantially contacts the inner peripheral surface of the bulging portion 33 of the guide tube 30.

  Hereinafter, other embodiments of the present invention will be described.

  (1) In the above embodiment, the shape of the bulging portion 33 of the guide tube 30 is not particularly limited, and the cross section of one half of the bulging portion 33 is, for example, a triangular shape as shown in FIG. Alternatively, for example, a trapezoidal shape as shown in FIG. 10 can be used.

  (2) In the above embodiment, the inner diameter dimension of the maximum inner diameter portion of the bulging portion 33 of the guide tube 30 is preferably set to be equal to or larger than the inner diameter dimension of the upper end side of the guide tube 30, that is, the other end 32 in the longitudinal direction.

  For example, as shown in FIG. 11, assuming that the inner diameter dimension of the other end side 32 of the guide tube 30 is the same as the inner diameter dimension of the maximum inner diameter portion of the bulging portion 33, The inner diameter may be constant.

  In the case of the guide tube 30 shown in FIG. 11, the facing distance between the other end side 32 of the guide tube 30 and the direct ignition 20 can be made larger than that in the above embodiment, so that, for example, the inclination angle at the initial extraction stage of the direct ignition 20 is further increased. It becomes possible to enlarge.

  (3) In the above-described embodiment, the spark plug 15 and the direct ignition 20 are exemplified as the rod-shaped member. However, the rod-shaped member may be a general plug cap, a direct injection injector, or the like other than those described above.

  Conventionally, some gasoline engines and diesel engines use a direct injection injector for directly injecting fuel into a combustion chamber. Among these, when the direct injection injector is disposed at the center of the combustion chamber 11 in the cylinder head 1, the guide tube 30 as described in the above embodiment is used as a guide tube serving as an attachment / detachment guide for the direct injection injector. It is possible.

  (4) In the above embodiment, the bulging portion 33 of the guide tube 30 has an example in which the bulging portion 33 of the guide tube 30 is bulged uniformly outward in the radial direction around the entire circumference in the longitudinal direction. You may make it provide locally only in the specific part of the circumferential direction, ie, the place which wants to ensure escape space at the time of attachment or detachment of a rod-shaped member.

  (5) In the above embodiment, the guide tube 30 is separated from the cylinder head 1, but a cylindrical guide portion such as the guide tube 30 may be provided integrally with the cylinder head 1.

It is an arrow view of the (1)-(1) line cross section of FIG. It is a top view showing one embodiment of a cylinder head using a guide tube concerning the present invention. It is a figure which shows the state which removed the direct ignition in FIG. It is a figure for demonstrating the removal initial stage of the direct ignition of FIG. FIG. 5 is a diagram for explaining the continuation of FIG. 4. FIG. 6 is a diagram for explaining the continuation of FIG. 5. FIG. 7 is a diagram for explaining the continuation of FIG. 6. It is a figure for demonstrating the cross-sectional shape of the bulging part in the guide tube shown in FIG. It is a figure corresponding to Drawing 1 in other embodiments of a guide tube concerning the present invention. It is a figure corresponding to Drawing 1 in other embodiments of a guide tube concerning the present invention. It is a figure corresponding to Drawing 1 in other embodiments of a guide tube concerning the present invention.

Explanation of symbols

1 Cylinder head 2 Cylinder head cover 2a Plug insertion / extraction hole (through hole)
DESCRIPTION OF SYMBOLS 3 Intake camshaft 4 Exhaust camshaft 5 Intake valve 6 Exhaust valve 15 Spark plug 15a Spark plug ignition part 15b Spark plug terminal nut 20 Direct ignition 21 Direct ignition cylindrical case 24 Direct ignition plug joint 30 Guide tube 31 One end side of the guide tube 32 The other end side of the guide tube 33 The bulging portion of the guide tube

Claims (6)

A guide tube that serves as a guide when a rod-like member of an ignition system or a fuel supply system is detachably mounted on a cylinder head of an internal combustion engine with one end in the longitudinal direction exposed to a combustion chamber,
The longitudinal direction one end side is attached so as to cover the rod-shaped member mounting region in the cylinder head, and the longitudinal direction other end side is attached so as to communicate with the through hole provided in the cylinder head cover,
A guide tube characterized in that an escape space is provided on the inner side in the longitudinal direction to allow a radially outward movement of the rod-shaped member on the distal side in the mounting direction when the rod-shaped member is attached and detached.   2. The inner diameter of the other end in the longitudinal direction according to claim 1 is larger than the inner diameter of one end in the longitudinal direction, and in the middle of the longitudinal direction, the inner diameter is outward in the radial direction so as to be larger than the one end. A guide tube characterized in that a bulging portion swelled is provided, and the escape space is secured on the inner diameter side of the bulging portion.   The bulging portion according to claim 2, wherein the bulging portion has a barrel shape by having a maximum inner diameter at the center in the longitudinal direction and gradually reducing the diameter from the maximum inner diameter portion toward both sides in the longitudinal direction. Characteristic guide tube.   In Claim 2 or 3, the shape of the half of the bulging portion in a cross section along its longitudinal direction is such that the tip end edge of the rod-shaped member is attached in the process of tilting the posture while taking out the rod-shaped member. A guide tube that is curved in the longitudinal direction in accordance with a moving locus to be drawn. A guide tube that serves as a guide when a rod-like member of an ignition system or a fuel supply system is detachably mounted on a cylinder head of an internal combustion engine with one end in the longitudinal direction exposed to a combustion chamber,
The longitudinal direction one end side is attached so as to cover the rod-shaped member mounting region in the cylinder head, and the longitudinal direction other end side is attached so as to communicate with the through hole provided in the cylinder head cover,
A guide tube characterized in that a bulging portion bulging outward in the radial direction is provided on the inner side in the longitudinal direction. A spark plug that burns an air-fuel mixture in a combustion chamber of an internal combustion engine, a direct ignition that is removably attached to the spark plug and applies an ignition voltage, and is provided so as to cover the spark plug and the direct ignition. And a guide tube that serves as a guide when the spark plug is attached / detached and when the direct ignition is attached / detached,
A cylinder head characterized in that the guide tube has the structure according to any one of claims 1 to 5.

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