JP3009795B2 - Fuel supply piping structure of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine in which the upper end of a fuel injection nozzle is located in a space surrounded by a cylinder head and a cylinder head cover, and supplies fuel to the fuel injection nozzle from outside the cylinder head. The present invention relates to a structure of a fuel supply pipe, which penetrates a side wall of a cylinder head and a structure in the vicinity thereof.

[0002]

2. Description of the Related Art Japanese Utility Model Laid-Open Publication No. 1-133575 discloses a four-valve diesel engine in which a fuel injection nozzle is extended directly above a cylinder within a region surrounded by four valves, and an upper end of the fuel injection nozzle is connected to a cylinder head. Patent Document 1 discloses a structure of a fuel supply pipe to a fuel injection nozzle in a diesel engine located in a space surrounded by a cylinder head cover and a fuel injection nozzle. In this case, as shown in FIG. 10, a fuel supply nozzle 24 is inserted through a fuel injection nozzle body 22 located in a cylinder head 21 through a through hole 23 formed in a cylinder head side wall.
Are extended and connected in the cylinder head, and a gap between the cylinder head 21 and the fuel supply pipe 24 is sealed by an oil seal 25 extending into the cylinder head. 27.

[0003]

However, the above prior art has the following problems. Since the connection between the fuel injection nozzle and the fuel supply pipe is inside the cylinder head, it is not possible to visually check from the outside whether or not the tightening has been forgotten after the assembly is completed. Since the connection between the fuel injection nozzle and the fuel supply pipe is inside the cylinder head, if fuel leaks from the connection due to forgetting to tighten, etc., the leaked fuel is returned to the intake system together with blow-by gas and recirculated to the combustion chamber. , Resulting in overrun. In order to fix the oil seal, a plate and a bolt are required, and a space larger than the interval between the bolts is required. Therefore, the structure of the cylinder head penetrating portion becomes large and complicated. To detach the fuel injection nozzle from the cylinder head,
Not only is the fuel injection nozzle connected to the fuel supply pipe,
The structure requires the removal and attachment of other members (bolts, plates, oil seals). For this reason, maintenance (service) work that requires the attachment and detachment of the fuel injection nozzle becomes difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel for an internal combustion engine in which a connection between a fuel injection nozzle and a fuel supply pipe can be located outside a cylinder head, and the fuel injection nozzle can be easily attached to and detached from the cylinder head. It is to provide a supply piping structure.

[0005]

The fuel supply piping structure of the internal combustion engine according to the present invention for achieving the above object has the following piping structure. That is, a fuel injection nozzle whose upper end is located in a space surrounded by a cylinder head and a cylinder head cover, and a recess formed in the side wall of the cylinder head from the upper end of the side wall toward the side wall, and is removably fitted and penetrated there. A plug having the same shape as the recess formed with the hole, and a fuel extending from the space enclosed by the cylinder head and the cylinder head cover through the through hole of the plug integrally attached to the fuel injection nozzle and extending out of the cylinder head. An intake pipe, a fuel supply pipe connected to the fuel intake pipe outside the cylinder head, and an oil seal provided between the plug and the fuel intake pipe to seal between the plug and the fuel intake pipe. Fuel supply piping structure for an internal combustion engine.

[0006]

In the above piping structure, the fuel intake pipe is integrally attached to the fuel injection nozzle and serves as a member on the fuel injection nozzle side. Since the fuel intake pipe extends out of the cylinder head and is connected to the fuel supply pipe, the connection between the fuel injection nozzle and the fuel supply pipe is located outside the cylinder head. For this reason, even after the assembly is completed, the connecting portion can be visually checked, and even if fuel leaks to the connecting portion due to forgetting to tighten or the like, it does not mix with the blow-by gas, so that overrun does not occur. In addition, a semicircular notch is provided in the cylinder head, and a semicircular plug is attached to it,
Since the fuel intake pipe is inserted through the hole formed in this plug, during maintenance, simply disconnect the connection between the fuel intake pipe and the fuel supply pipe, and remove the fuel injection nozzle from the cylinder head together with the plug and oil seal. It is not necessary to disassemble other members, and maintenance is easy. Further, since the mounting structure is not provided by bolts or the like, the structure is compact and simple.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Three embodiments according to the present invention will be described. FIG.
5 shows the first embodiment, FIGS. 6 and 7 show the second embodiment, and FIGS. 8 and 9 show the third embodiment. The structural parts common to all the embodiments are denoted by the same reference numerals throughout all the embodiments.

First, a structure common to all embodiments will be described with reference to FIGS. As shown in FIGS. 1 and 2, a piston 10 is inserted into a cylinder bore of a cylinder block 9 of an internal combustion engine, for example, a diesel engine, and a recess is formed at the top of the piston to form a combustion chamber. The cylinder head 1 is fixed on the cylinder block 9 and covers the combustion chamber from above. The cylinder head 1 is formed with two intake ports and two exhaust ports, for example, to form a four-valve engine.

A fuel injection nozzle 2 is arranged at a center of each cylinder and surrounded by four valves, and is mounted on a cylinder head 1. The lower end of the fuel injection nozzle 2 faces the cylinder,
Inject fuel into the combustion chamber. The fuel injection nozzle 2 extends upward in the cylinder axis direction, and its upper end protrudes into a space surrounded by the cylinder head 1 and the cylinder head cover 7. The fuel injection nozzle 2 has a shoulder near the upper end, and has a laterally extending portion 2a that extends laterally at a position slightly below the shoulder. The fuel injection nozzle 2 is inserted into a vertically extending nozzle insertion hole formed in the cylinder head 1,
The shoulder is held down by the clamp 3, and the clamp 3 is mounted and fixed to the cylinder head 1 by tightening the clamp 3 with a clamping bolt 8 screwed into the cylinder head 1.

A fuel intake pipe 11 is integrally attached to the fuel injection nozzle 2 to form a fuel injection nozzle side. The fuel intake pipe 11 penetrates the side wall 1a of the cylinder head 1 and extends out of the cylinder head 1 from a space surrounded by the cylinder head 1 and the cylinder head cover 7. The supply of fuel to the fuel injection nozzle 2 is performed through a fuel intake pipe 11. A screw is cut around the outer periphery of the tip of the fuel intake pipe 11.

The fuel supply pipe 5 is located outside a space surrounded by the cylinder head 1 and the cylinder head cover 7, and is connected to the fuel intake pipe 11 outside the cylinder head 1. Therefore, the connection between the fuel intake pipe 11 and the fuel supply pipe 5 is located outside the cylinder head 1.
The fuel supply pipe 5 is connected to a fuel intake pipe 11 by a nut 6. The nut 6 is connected to the fuel intake pipe 11
The connection part is sealed by pressing a seat member 5a fixed or integrally formed at the tip of the fuel supply pipe 5 against the tip of the fuel intake pipe 11 by being screwed into a screw provided on the outer periphery of the tip of the fuel supply pipe 5. I have.

A semicircular notch 1b is formed in the side wall 1a of the cylinder head 1 as a depression in the side wall direction of the side wall. The center of curvature of this semicircle is at the same height as the upper end of the cylinder head side wall 1a, and the semicircular notch 1b is open upward.

A semicircular plug 12 is detachably fitted in the semicircular notch 1b of the cylinder head side wall 1a. The contact surface between the semicircular notch 1b and the plug 12 is a sealing surface, for example, coated with a liquid gasket. The plug 12 has the same thickness as the cylinder head side wall 1a. However, the thickness of the plug 12 may be greater than the cylinder head side wall thickness as long as the sealing property between the plug and the nozzle can be ensured. Such a plug can be the same as the semicircular plug used to plug the cam journal machining hole of the cylinder head, and the seal between the plug and the cylinder head machining hole by the liquid gasket has been proven. . The semicircular plug 12 is provided with a through hole 13 (a hole 15 in the second embodiment and a hole 17 in the third embodiment) in the thickness direction. The fuel intake pipe 11 extends inside and outside the cylinder head 1 by passing through the through hole 13. Therefore, the diameter of the through hole 13 is larger than that of the fuel intake pipe 11. The clearance between the through hole 13 and the fuel intake pipe 11, the mounting position and mounting angle of the fuel injection nozzle 2 can be adjusted.

A space surrounded by the cylinder head 1 and the cylinder head cover 7 is a space in which the valve operating system lubricating oil scatters, and a space in which blow-by gas flows. Therefore, the portion of the fuel intake pipe 11 where the plug 12 penetrates must be sealed. In this sense, the oil seal 4 (the second seal) is provided between the fuel intake pipe 11 and the plug 12.
A seal 16 is provided in the embodiment, and a seal 18 is provided in the third embodiment. Through hole 13 and oil seal 4
Have different structures in each embodiment.

Next, a configuration specific to each embodiment will be described.
In the first embodiment, as shown in FIGS. 1 to 5, a through hole 13 formed in a plug 12 has two portions 13a, 1a.
3b, the first part 13a being the fuel intake pipe 1
1, the second portion 13b is a long hole (FIG. 5), and the long axis direction of the long hole is equal to the circular diameter of the first portion 13a, and is short. The axial direction is slightly larger than the outer diameter of the fuel intake pipe 11. The long hole of the second portion 13b has its long axis set in the up-down direction. Thereby, the horizontal deflection of the fuel intake pipe 11 due to the displacement of the fuel injection nozzle 2 around the nozzle axis is restricted by the short-axis edge of the second portion 13b. Highly accurate positioning around the core.

As shown in FIG. 1, the oil seal 4 is sealed by being driven into the first portion 13a of the through hole 13 at one end 4a.
It extends inward, is fitted on the outer periphery of the fuel intake pipe 11 at the other end 4b, and is pressed and sealed by the ring 4c. The oil seal 4 is made of rubber, and a metal ring 4d is embedded in a portion (the one end 4a) driven into the through hole 13. The oil seal 4 can be deformed at a portion other than the portion where the metal ring 4d is embedded.
Some misalignment during mounting can be absorbed.

In the second embodiment, as shown in FIGS. 6 and 7, the through hole 15 formed in the semicircular plug 12 is circular, and has the same diameter over the entire length of the hole. The fuel intake pipe 11 passes through the through hole 15. A rubber O-ring 16 is inserted between the inner peripheral surface of the through hole 15 and the outer peripheral surface of the fuel intake pipe 11. Within the range of the elastic deformation of the O-ring 16, the displacement of the mounting of the fuel injection nozzle 2 is absorbed.

In the third embodiment, as shown in FIGS. 8 and 9, the through hole 17 formed in the semicircular plug 12 has two holes.
The first part 17a is a large circle having a diameter about twice the diameter of the O-ring than the outer diameter of the fuel intake pipe 11, and the second part 17b is a long hole.
The long axis direction of the long hole is equal to the circular diameter of the first portion 17a, and the short axis direction is larger in diameter than the outer diameter of the fuel intake pipe 11, but larger than the diameter of the first portion 17a. Is small. The long axis direction of the second portion is set in the up-down direction.

An O-ring 18 made of rubber is inserted between the inner peripheral surface of the first portion 17 a of the through hole 17 and the outer peripheral surface of the fuel intake pipe 11. Within the range of the elastic deformation of the O-ring 18, the displacement of the mounting of the fuel injection nozzle 2 is absorbed. However, since the diameter of the second portion 17b of the through hole 17 is reduced in the horizontal direction, the displacement of the fuel injection nozzle 2 around the nozzle axis is restricted by the edge of the second portion 17b. Thereby, large elastic deformation is suppressed from being applied to the O-ring 18, and oil leakage due to excessive deformation of the O-ring 18 is prevented.

Next, the operation of the present invention (common to each embodiment)
Will be described. The fuel intake pipe 11 is connected to the fuel injection nozzle 2
Are integrally connected to form a fuel injection nozzle side member,
At the tip of the fuel intake pipe 11, the fuel injection nozzle side is connected to the fuel supply pipe 5. Therefore, the connection between the fuel injection nozzle and the fuel supply pipe 5 is outside the cylinder head 1. For this reason, even after the cylinder head cover 7 is attached to the cylinder head 1, the connecting portion can be visually checked, and whether the nut 6 has been forcibly tightened, or the fuel leaks from the connecting portion due to the forgetting of the nut 6 tightening. Can be checked to see if any has occurred.

If the connecting portion is in a space surrounded by the cylinder head 1 and the cylinder head cover 7 and fuel leaks from the connecting portion, the leaked fuel is mixed with blow-by gas and recirculated to the combustion chamber, and overrun is performed. However, if the connecting portion is outside the cylinder head 1 as in the present invention, even if fuel leaks from the connecting portion, overrun does not occur and the fuel can be immediately sensed by smell or the like, and measures can be taken. It can be said that it is safer.

The oil seals 4, 16, and 18 are connected to the plug 1
2 is inserted into the through hole 13 or inserted between the plug 12 and the fuel intake pipe 11, and is not fixed by the plate 26 and the bolt 27 as in the related art. In the case of fixing with the bolt 27, there is a problem that an installation space for the space between the bolts 27 is required at a minimum and it is difficult to assemble an oil seal to an engine whose installation space is restricted. The mounting space is small because the mounting is not performed by the mounting method, and the mounting structure and the design are easy. This is preferable from the viewpoint of cost reduction.

The structure of the present invention facilitates maintenance (service). That is, when it is necessary to remove the fuel injection nozzle 2 from the cylinder head 1 during maintenance, the cylinder head cover 7 is removed from the cylinder head 1, the clamp 3 is removed, and then the nut 6 is loosened and the fuel supply pipe 5 is taken in. The fuel injection nozzle 2 can be removed together with the plug 12 and the oil seals 4, 16, and 18 simply by removing the fuel injection nozzle 2 from the pipe 11. There, the bolt 27, the plate 2
6. There is no need to remove the oil seal 25. At the time of installation, it can be installed in the reverse procedure, and the oil seals 4, 1
There is no need to reset 6 and 18. This not only reduces the number of man-hours, but also eliminates the need for time-consuming handling of the oil seal, thereby greatly simplifying maintenance work.

[0024]

According to the present invention, the connecting portion between the fuel injection nozzle side and the fuel supply pipe is located outside the cylinder head, the fuel intake pipe is inserted through the semicircular plug, and the plug is inserted between the plug and the fuel intake pipe. Since the oil seal is provided, the connecting portion can be visually checked from outside the cylinder head, and the fuel injection nozzle together with the plug and the oil seal can be attached to and detached from the cylinder head, thereby facilitating maintenance.

[Brief description of the drawings]

FIG. 1 is an enlarged plan view of a fuel supply pipe structure of an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the fuel supply pipe structure of FIG.

FIG. 3 is a plan view of the plug of FIG. 1;

FIG. 4 is a left side view of the plug of FIG. 3;

FIG. 5 is a right side view of the plug of FIG. 3;

FIG. 6 is an enlarged plan view of a cylinder head penetration portion and its vicinity in a fuel supply pipe structure of an internal combustion engine according to a second embodiment of the present invention.

FIG. 7 is a front view of the plug of FIG. 6;

FIG. 8 is a front view of a plug of a fuel supply pipe structure for an internal combustion engine according to a third embodiment of the present invention.

FIG. 9 is a sectional view of a part of the plug of FIG. 8;

FIG. 10 is a sectional view of a conventional fuel supply pipe structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 1a Cylinder head side wall 1b Semicircular notch 2 Fuel injection nozzle 4 Oil seal 5 Fuel supply pipe 6 Nut 7 Cylinder head cover 11 Fuel intake pipe 12 Semicircular plug 13 Through hole 15 Through hole 16 Oil seal 17 Through hole 18 Oil sticker

────────────────────────────────────────────────── ─── Continued on the front page (72) Yoshimitsu Hayashi 2-1-1, Toyotamachi, Kariya, Aichi Prefecture Inside Toyota Industries Corporation (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 61 / 14 320 F02M 61/16 F02M 55/02 330 F02F 1/00-1/42 F02F 11/00

Claims (1)

(57) [Claims] 1. A fuel injection nozzle having an upper end located in a space surrounded by a cylinder head and a cylinder head cover, and a recess formed in a side wall of the cylinder head from an upper end of the side wall to a side wall direction to be detachably fitted therein. A plug having the same shape as the recess having a through hole formed therein, and a plug which is integrally attached to the fuel injection nozzle, is inserted through the through hole of the plug, and is outside the cylinder head from a space surrounded by the cylinder head and the cylinder head cover. A fuel supply pipe connected to the fuel intake pipe outside the cylinder head, and an oil seal provided between the plug and the fuel intake pipe to seal between the plug and the fuel intake pipe. And a fuel supply piping structure for an internal combustion engine.