JP6449656B2 - Plug pipe mounting structure - Google Patents

Description

  The present invention relates to a plug pipe mounting structure.

Natural gas vehicles equipped with gas engines that use natural gas as fuel will generate significantly less harmful substances (black smoke, NOx, SOx, etc.) in the exhaust gas than vehicles equipped with diesel engines that use light oil as fuel, and generate heat. Since CO ₂ emissions per unit are the lowest among fossil fuels, it is being introduced as an environmental measure and a measure against global warming. However, the number of popular vehicles has been sluggish due to high initial introduction costs. It is.

  As shown in FIG. 6 and FIG. 7, there is a case where the natural gas automobile with a small number of popularizations uses a cylinder head 1 of a diesel engine with a large number of popularizations to reduce the cost. A plug pipe 3 is inserted in place of the injector in a position corresponding to each cylinder of the head 1, and a plug hole 5 for disposing the spark plug 4 is defined by the plug pipe 3, and penetrates through the bottom of the plug pipe 3. The tip of the mounted spark plug 4 faces the combustion chamber 6.

  That is, when the cylinder head 1 of a diesel engine is diverted, the plug hole is not provided in the cylinder head 1 as in the case of a new spark ignition engine from the beginning. 5, and by inserting the plug pipe 3 in this way, cooling water for the water jacket 7 in the cylinder head 1 and oil mist from the valve system that scatters on the cylinder head 1. Thus, the spark plug 4 is isolated and protected from the above.

  Here, a male screw is engraved at the tip 8 of the spark plug 4 protruding from the bottom of the plug pipe 3, and the spark plug 4 is tightened into a screw hole 9 formed on the cylinder head 1 side. The center electrode 10a and the ground electrode 10b at the projecting end of the tip 8 of the spark plug 4 are fixed downward from the bottom surface of the cylinder head 1 (the ceiling surface of the combustion chamber 6). It is supposed to be exposed.

  At this time, the bottom portion of the plug pipe 3 having a larger outer diameter than the tip portion 8 of the spark plug 4 is supported in a state of abutting against the support portion 11 around the screw hole 9. A copper gasket 12 is interposed between the bottom of the plug pipe 3 and a flange 13 formed on the outer periphery of the middle of the plug pipe 3 is fastened to the upper surface of the cylinder head 1 with bolts 14. Then, the gasket 12 is held under pressure by being pushed down to ensure high sealing performance.

  Here, the ignition plug 4 can be tightened into the screw hole 9 by inserting an elongated socket wrench into the plug pipe 3, and a pressing force can be applied to the plug pipe 3 by this tightening. However, since there is a possibility that the spark plug 4 may be detached during maintenance, it is necessary to employ a push-down method using the flange portion 13 so as to ensure sealing performance independently from the removal of the spark plug 4. is there.

  Further, the portion of the plug pipe 3 that is internally fitted to the cylinder head 1 above the lower portion in contact with the water jacket 7 is formed by the O-rings 15 and 16 disposed on the cylinder head 1 side. The gap between the plug pipe 3 side and the cylinder head 1 side is closed to ensure high sealing performance.

  Incidentally, as prior art document information relating to the attachment of the spark plug via this type of plug pipe, there is the following Patent Document 1 and the like.

JP 2002-276523 A

  However, in such a conventional structure, a single plug pipe 3 extending from the bottom surface of the cylinder head 1 to the ceiling surface of the head cover 2 is used. Is difficult to machine, and the flange portion 13 must be formed on the outer periphery of the middle portion of the plug pipe 3 and fastened to the upper surface of the cylinder head 1. As a result, a lot of work was required, resulting in poor workability and high costs.

  Further, when the cylinder head 1 assembled with the plug pipe 3 as shown by the solid line in FIG. 6 is handled at the maintenance site, a large number of plug pipes 3 are formed in a chimney shape from the upper part of the cylinder head 1. Since it protrudes, there is also a problem that it is difficult to handle the cylinder head 1 so that it does not come into contact with surrounding objects and the portability is poor.

  The present invention has been made in view of the above circumstances, and provides a plug pipe mounting structure that realizes improvement in workability and cost reduction and facilitates handling of a sub-assembled cylinder head at a maintenance site. For the purpose.

The present invention relates to a plug pipe mounting structure that is inserted into a position corresponding to each cylinder of a cylinder head and that defines a plug hole for arranging a spark plug by the insertion. Is divided into an upper plug pipe and a lower plug pipe at a position where the external fitting can be held below the upper surface of the cylinder head, and the plug pipe side and the cylinder head side are separated by a sealing means at an upper and lower position sandwiching the divided portion. A first screw hole communicating with the combustion chamber is formed in the support portion on the cylinder head side that closes the gap and supports the bottom portion of the lower plug pipe, and the lower plug pipe is connected to the first screw hole. A screw part projecting from the center of the bottom part is tightened and screwed, and at the time of the screwing, a lower plug pipe bottom part around the screw part and a support part around the first screw hole A gasket is sandwiched and held between them, and the tip of the spark plug is tightened and screwed into a second screw hole formed in the axial center portion of the screw portion. The center electrode and the ground electrode at the protruding end of the portion are exposed to the combustion chamber side, and further , notch portions are formed at a plurality of circumferential positions on the upper end surface of the lower plug pipe and can be fitted to the notch portions. It is characterized in that the screw portion of the lower plug pipe can be tightened into the first screw hole by a dedicated tool that has a protrusion and can be brought into contact with the upper end surface of the lower plug pipe .

  Thus, by dividing the plug pipe into the upper plug pipe and the lower plug pipe, the length dimension as a part is reduced, so that the inner holes of the upper plug pipe and the lower plug pipe are machined. In addition, it is possible to hold down and hold the gasket by applying a pressing force by tightening the screw part of the plug pipe itself into the first screw hole. It is no longer necessary to form a flange portion, and it is possible to reduce the number of man-hours for fastening, thereby improving workability and reducing costs as compared with the prior art.

  In addition, for the divided upper stage plug pipe, it is only necessary to set the fitting insertion diameter narrowed by the sealing means and then press-fit by fixing it, so when substituting the cylinder head at the maintenance site, Only the lower plug pipe is assembled in advance, and maintenance work is performed so that a large number of upper plug pipes do not protrude in a chimney shape from the top of the cylinder head. After the maintenance work, the upper plug pipe can be retrofitted. It becomes easy to handle the head so that it does not come into contact with surrounding objects during maintenance work, and the portability can be greatly improved.

Furthermore, in the present invention, a notch is formed at a plurality of locations in the circumferential direction on the upper end surface of the lower plug pipe, and a protrusion that can be fitted to each notch is provided to be able to abut against the upper end surface of the lower plug pipe. Since the screw portion of the lower plug pipe can be tightened into the first screw hole by a tool, the protrusion of the dedicated tool is fitted into the notch portion of the upper end surface of the lower plug pipe, and the dedicated tool Thus, the screw portion of the lower plug pipe can be easily tightened into the first screw hole.

  Further, in the present invention, it is preferable that the first screw hole and the second screw hole are engraved with female threads opposite to each other. In this way, the spark plug is replaced when the spark plug is replaced. Even when the sticking is difficult to remove, the situation where the lower plug pipe rotates together with the spark plug and becomes loose is avoided.

  Furthermore, in the present invention, the lower plug pipe can be made of metal and the upper plug pipe can be made of resin, and the upper plug pipe has a lower thermal load than the lower plug pipe having a high heat load. It is possible to facilitate the manufacturing process by using a pipe made of resin.

  According to the plug pipe mounting structure of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, the plug pipe is divided into the upper plug pipe and the lower plug pipe, so that the length dimension as a part is reduced and the inner hole is easily machined. In addition, by tightening the threaded portion of the plug pipe itself into the first threaded hole, it is possible to hold the gasket so that it does not need to be formed with a flange portion, and man-hours for fastening are also saved. As a result, it is possible to improve workability and reduce costs compared to the conventional method.In addition, when sub-assembling the cylinder head at the maintenance site, only the lower plug pipe is assembled in advance and the cylinder head is installed from the top. Maintenance work can be performed so that a large number of upper plug pipes do not protrude in a chimney shape. To handle so as not to contact the periphery of things become readily can be achieved significant improvement in portability.

(II) According to the invention described in claim 1 of the present invention, the projection of the special tool is fitted in the notch of the upper end face of the lower plug pipe, first the screw portion of the lower plug pipe by the special tool Since it can be easily tightened into one screw hole, the assembly work can be easily performed even if the plug pipe is divided into an upper plug pipe and a lower plug pipe.

(III) According to the invention described in claim 2 of the present invention, even when the spark plug is fixed and difficult to remove when replacing the spark plug, the situation where the lower plug pipe rotates together with the spark plug and is loosened is avoided. This makes it possible to easily replace the spark plug.

(IV) According to the invention described in claim 3 of the present invention, the upper plug pipe can be made of resin, facilitating the manufacturing process, and further improving workability and reducing costs. it can.

It is sectional drawing which shows an example of the form which implements this invention. It is sectional drawing which expands and shows the principal part of FIG. It is sectional drawing which shows the state which removed the upper stage plug pipe of FIG. It is sectional drawing which shows another example of a form of this invention. It is sectional drawing which shows another example of a form of this invention. It is sectional drawing which shows the conventional structure regarding attachment of a plug pipe. It is sectional drawing in the attachment position of the plug pipe of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 3 show an example of an embodiment for carrying out the present invention, and portions denoted by the same reference numerals as those in FIGS. 6 and 7 represent the same items.

  As shown in FIGS. 1 to 3, in the present embodiment, a plug hole 5 is inserted into a position corresponding to each cylinder of the cylinder head 1 and the spark plug 4 is arranged by the insertion. With regard to the mounting structure of the plug pipe 17, the plug pipe 17 is divided into an upper plug pipe 17 A and a lower plug pipe 17 B at a position where it can be externally fitted below the upper surface of the cylinder head 1, and the divided portion is sandwiched. The gap between the plug pipe 17 side and the cylinder head 1 side is closed by O-rings 15 and 16 (seal means: the upper O-ring 15 may be replaced with a liquid seal or the like) in the vertical position. Here, since the thermal load of the upper plug pipe 17A is smaller than that of the lower plug pipe 17B having a high thermal load, the lower plug pipe 17B can be made of metal and the upper plug pipe 17A can be made of resin.

  Further, a screw hole 18 (first screw hole) communicating with the combustion chamber 6 is formed in the support portion 11 on the cylinder head 1 side that supports the bottom portion of the lower plug pipe 17B. On the other hand, a screw portion 19 protruding from the center of the bottom of the lower plug pipe 17B is tightened and screwed, and the lower plug pipe 17B bottom around the screw portion 19 and the support portion 11 around the screw hole 18 are screwed. The gasket 12 is held between the two.

  Here, notches 20 are formed at a plurality of circumferential positions on the upper end surface of the lower plug pipe 17B, and protrusions 21 that can be fitted to the notches 20 are provided on the upper end surface of the lower plug pipe 17B. The threaded portion 19 of the lower plug pipe 17B can be tightened into the screw hole 18 by a dedicated tool 22 that can be abutted (see FIG. 3).

  Further, the tip portion 8 of the spark plug 4 is tightened and screwed into a screw hole 23 (second screw hole) drilled in the axial center portion of the screw portion 19, and the spark plug 4 The center electrode 10a and the ground electrode 10b at the protruding end of the tip 8 are also exposed to the combustion chamber 6 side.

  At this time, the screw hole 18 and the screw hole 23 are provided with female threads opposite to each other. Even when the spark plug 4 is fixed when the spark plug 4 is replaced, it is difficult to remove the lower plug pipe 17B. Can be prevented from loosening along with the spark plug 4.

  Thus, if such a structure is adopted, the length of the plug pipe 17 is reduced by dividing the plug pipe 17 into the upper plug pipe 17A and the lower plug pipe 17B, so the upper plug pipe 17A and the lower plug The inner hole of the pipe 17B can be easily machined, and the screw portion of the plug pipe 17 itself is tightened into the screw hole 18 so that a pressing force can be applied to hold the gasket 12 under pressure. Therefore, it is no longer necessary to form the flange portion 13 (see FIG. 7) on the outer periphery of the middle portion of the plug pipe 17, and it is possible to reduce the man-hours for fastening, improving workability and reducing costs compared to the conventional case. Will be planned.

  In addition, the divided upper stage plug pipe 17A may be fixed by being pressed and fixed by setting the fitting insertion diameter narrowed by the O-ring 15 appropriately, so that the cylinder head 1 is sub-assembled at the maintenance site. In this case, only the lower plug pipe 17B is assembled in advance, and maintenance work is performed so that a large number of upper plug pipes 17A do not protrude in a chimney shape from the upper part of the cylinder head 1, and after the maintenance work, the upper plug pipe 17A. It is easy to handle the cylinder head 1 so that it does not come into contact with surrounding objects during maintenance work, and the portability can be greatly improved.

  Therefore, according to the above-described embodiment, the plug pipe 17 is divided into the upper plug pipe 17A and the lower plug pipe 17B, thereby reducing the length as a part and making the machining of the inner hole easy. By tightening the screw portion of the plug pipe 17 itself into the screw hole 18, the gasket 12 can be held with pressure so that the formation of the flange portion 13 (see FIG. 7) is not required, and the number of man-hours for the fastening is also reduced. Therefore, the workability can be improved and the cost can be reduced as compared with the prior art. In addition, when substituting the cylinder head 1 at the maintenance site, only the lower plug pipe 17B is assembled in advance. Maintenance work can be performed so that a number of upper plug pipes 17A do not protrude in a chimney shape from the upper part of 1. , It is possible to greatly improve the portability becomes easy to handle the cylinder head 1 so as not to contact the periphery of things during maintenance work.

  Further, the protruding portion 21 of the dedicated tool 22 is fitted into the notch 20 on the upper end surface of the lower plug pipe 17B, and the screw portion 19 of the lower plug pipe 17B is simply tightened into the screw hole 18 by the dedicated tool 22. Therefore, even if the plug pipe 17 is divided into the upper plug pipe 17A and the lower plug pipe 17B, the assembling work can be easily performed.

  Further, even when the spark plug 4 is fixed and difficult to remove at the time of replacement of the spark plug 4, it is possible to avoid the situation where the lower plug pipe 17B rotates together with the spark plug 4 and loosens. In addition, the upper stage plug pipe 17A can be made of resin to facilitate the manufacturing process, thereby further improving the workability and reducing the cost.

  FIG. 4 shows another embodiment of the present invention. A positioning collar 24 that contacts the upper surface of the cylinder head 1 when the upper plug pipe 17A is normally inserted in the outer periphery of the middle part of the upper plug pipe 17A. In this case, it can be confirmed from the outside whether or not the upper plug pipe 17A has been normally inserted to a depth that reaches the upper end surface of the lower plug pipe 17B.

  FIG. 5 shows still another embodiment of the present invention, in which the lower end portion of the upper stage plug pipe 17A is thickened and an O-ring 15 is provided on the lower end portion side. In this case, the upper stage plug pipe 17A can be inserted and removed together with the O-ring 15 and the O-ring 15 can be easily replaced.

  It should be noted that the plug pipe mounting structure of the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Cylinder head 4 Spark plug 5 Plug hole 6 Combustion chamber 8 Tip part 11 Support part 12 Gasket 15 O-ring (sealing means)
16 O-ring (sealing means)
17 Plug pipe 17A Upper plug pipe 17B Lower plug pipe 18 Screw hole (first screw hole)
19 Screw part 20 Notch part 21 Projection part 22 Dedicated tool 23 Screw hole (second screw hole)

Claims (3)

A plug pipe mounting structure that is inserted into a position corresponding to each cylinder of a cylinder head and that defines a plug hole for arranging a spark plug by the insertion, wherein the plug pipe is connected to the cylinder head. The upper plug pipe and the lower plug pipe are divided at the position where the external fitting can be held below the upper surface, and the gap between the plug pipe side and the cylinder head side is closed by the sealing means at the upper and lower positions sandwiching the divided portion, A first screw hole communicating with the combustion chamber is formed in the support portion on the cylinder head side that supports the bottom portion of the lower plug pipe, and the first screw hole projects into the center of the bottom portion of the lower plug pipe. The provided screw part is tightened and screwed, and at the time of the screwing, there is a gap between the bottom plug pipe bottom around the screw part and the support part around the first screw hole. The tip of the spark plug is tightened and screwed into a second screw hole formed in the axial center portion of the screw portion, and the tip of the tip portion of the spark plug is screwed. The center electrode and the ground electrode are exposed to the combustion chamber side, and further , notches are formed at a plurality of circumferential positions on the upper end surface of the lower plug pipe, and protrusions that can be fitted to the notches are provided. The plug pipe mounting structure is characterized in that the threaded portion of the lower plug pipe can be tightened into the first screw hole by a dedicated tool that can be brought into contact with the upper end surface of the lower plug pipe . The plug pipe mounting structure according to claim 1 , wherein the first screw hole and the second screw hole are provided with female screws in opposite directions. The plug pipe mounting structure according to claim 1 or 2 , wherein the lower plug pipe is made of metal and the upper plug pipe is made of resin.

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