JP7435211B2 - engine structure - Google Patents

Description

The present invention relates to engine structure.

A conventional engine structure is disclosed in Patent Document 1. This engine structure includes an engine head and an injector. Although there is no specific description in this document, the engine head forms a combustion chamber together with the cylinder block. Further, the engine head is formed with an insertion hole that communicates with the combustion chamber and extends in the axial direction away from the combustion chamber. The injector is inserted into the insertion hole. The insertion hole has a first insertion hole, a seat surface, and a second insertion hole. The first insertion hole communicates with the combustion chamber and extends in the axial direction. The seat surface is continuous with the first insertion hole at the inner circumferential edge, and expands in diameter from the inner circumferential edge toward the outer circumferential edge in a direction perpendicular to the axial direction. The second insertion hole extends in the axial direction continuously from the outer peripheral edge of the seat surface.

The injector has a nozzle and a retaining nut. Further, although this document does not specifically describe it, the injector has a body that is fixed to the engine head. The nozzle is located closer to the combustion chamber than the body and extends in the axial direction toward the combustion chamber. An injection hole for injecting fuel is formed in the nozzle. The retaining nut is inserted through the body and the nozzle, and fastens the body and the nozzle in the axial direction. Further, the retaining nut faces the seat surface in the axial direction within the insertion hole.

More specifically, the nozzle has a distal end, a proximal end, and a connecting section. The tip portion is located on the combustion chamber side in the axial direction, and has an injection hole formed therein. The proximal end is located on the body side in the axial direction and has a larger diameter than the distal end. The base end portion faces and abuts the retaining nut in the axial direction, and is fastened to the body by the retaining nut. The connecting portion is located between the distal end and the proximal end, and is connected to the distal end and the proximal end.

Further, in this engine structure, a gasket is provided between the engine head and the injector. More specifically, the gasket is held between the seat surface and the retaining nut. As a result, in this engine structure, the tip of the nozzle protrudes further toward the combustion chamber than the retaining nut and gasket. On the other hand, the base end portion and the connecting portion of the nozzle are located within the retaining nut closer to the body than the gasket.

In this engine structure, an injector injects fuel into a combustion chamber through an injection hole. While the fuel injected into the combustion chamber burns in the combustion chamber, corrosive bodies are inevitably generated. Examples of this corrosive body include combustion gas containing sulfuric acid, nitric acid, nitrogen oxides, and the like, as well as condensed water produced by condensation of this combustion gas. In this regard, in this engine structure, the gasket prevents corrosive bodies from leaking to the outside of the engine head.

Japanese Patent Application Publication No. 2016-180390

However, in the conventional engine structure described above, the tip of the nozzle protrudes further toward the combustion chamber than the retaining nut and gasket, so the tip is exposed to corrosive bodies. Furthermore, it is inevitable that some of the corrosive bodies generated within the combustion chamber will pass between the tip of the nozzle and the gasket. Therefore, the nozzle is corroded by the corrosive body. As a result, with this engine structure, it is difficult to improve the durability of the nozzle and, by extension, the injector.

For this reason, forming a plating layer such as chrome plating on the surface of the nozzle may be considered, but the effect of the plating layer cannot be sufficiently exerted on the surfaces of the base end portion and the connecting portion of the nozzle. This is because, when the body and the nozzle are fastened together with the retaining nut, the base end of the nozzle abuts against the retaining nut while facing the retaining nut in the axial direction. By fixing the body to the engine head in this state, the base end portion continues to press the retaining nut in the axial direction. Therefore, stress from the retaining nut continues to act on the base end. Further, since the connecting portion of the nozzle is connected to the base end, tensile stress from the retaining nut is also applied to the connecting portion when the body is fixed to the engine head. For these reasons, in the above engine structure, even if a plating layer is formed on each surface of the proximal end and the connecting part, cracks are likely to occur in the plating layer, and the connecting part will be moved from the cracked area to the proximal end. This is because the parts will corrode.

The present invention has been made in view of the above-mentioned conventional situation, and an object to be solved is to provide an engine structure that can further improve the durability of an injector.

The engine structure of the present invention includes an engine head forming a combustion chamber, and an injector fixed to the engine head and injecting fuel into the combustion chamber,
The engine head is formed with an insertion hole that communicates with the combustion chamber and extends in an axial direction away from the combustion chamber in the axial direction of the injector, and into which the injector is inserted;
The insertion hole includes a first insertion hole that communicates with the combustion chamber and extends in the axial direction, and a first insertion hole that is continuous with the first insertion hole at an inner peripheral edge and extends from the inner peripheral edge to the outer peripheral edge in a direction perpendicular to the axial direction. a seat surface whose diameter increases toward the seat surface; and a second insertion hole extending in the axial direction continuously from the outer peripheral edge of the seat surface;
The injector includes a body fixed to the engine head;
a nozzle located closer to the combustion chamber than the body, extending in the axial direction toward the combustion chamber and having an injection hole formed therein for injecting the fuel;
a retaining nut that is inserted through the body and the nozzle, fastens the body and the nozzle in the axial direction, and faces the seating surface in the axial direction;
In the engine structure, a gasket is provided between the engine head and the injector, and the gasket is sandwiched between the seat surface and the retaining nut.
The nozzle has a tip portion located on the combustion chamber side in the axial direction and in which the injection hole is formed;
a proximal end located on the body side in the axial direction, having a larger diameter than the distal end, facing and abutting the retaining nut in the axial direction, and fastened to the body by the retaining nut; Department and
a connecting portion located between the distal end and the proximal end and connected to the distal end and the proximal end;
A plating layer is formed on the surface of the tip portion to protect the tip portion from corrosive substances generated when the fuel burns in the combustion chamber,
Between the distal end portion and the retaining nut, a lid is provided at a position closer to the body than the gasket in the axial direction for suppressing the corrosive bodies from reaching the connecting portion and the base end portion. A member is provided ,
The tip portion has the injection hole formed therein, and a first portion that protrudes toward the combustion chamber side beyond the retaining nut and the gasket and extends into the first insertion hole;
a second portion located within the retaining nut, having a larger diameter than the first portion, and connecting to the connecting portion;
The retaining nut is located between the first section and the second section, and is connected to the first section and increases in diameter from the first section side toward the second section side. It has a tapered part that connects the two parts,
The lid member is provided between the tapered portion and the retaining nut .

In the engine structure of the present invention, since a plating layer is formed on the surface of the tip of the nozzle, the tip can be prevented from being corroded by corrosive bodies. Further, in this engine structure, a lid member is provided between the tip end and the retaining nut at a position closer to the body than the gasket in the axial direction of the injector. Thereby, the lid member closes the gap between the distal end portion and the retaining nut, thereby suppressing corrosive bodies from reaching the connecting portion and the base end portion. Therefore, even if a plating layer is not formed on each surface of the connecting portion and the base end, the connecting portion and the base end are less likely to corrode. In addition, in this engine structure, the lid member prevents combustion gas as a corrosive body from reaching the connection part and the base end, thereby creating a gap between the connection part and the retaining nut, and between the base end and the retaining nut. It also becomes difficult for condensed water to form as a corrosive substance between the two. In this respect as well, with this engine structure, the connection portion and the base end portion are less likely to corrode. Thus, according to this engine structure, it is possible to suitably prevent each of the distal end, the connecting part, and the proximal end from being corroded by corrosive bodies.

Therefore, according to the engine structure of the present invention, the durability of the injector can be further improved.

The tip portion has an injection hole formed therein, and includes a first portion that protrudes toward the combustion chamber side beyond the retaining nut and gasket and extends into the first insertion hole, and a first portion that is located within the retaining nut and extends beyond the first portion. a second part that has a large diameter and connects to the connection part; and a second part that is located between the first part and the second part in the retaining nut, and that is connected to the first part and faces from the first part side to the second part side. It has a tapered part that increases in diameter toward the end and connects to the second part. The lid member is provided between the tapered portion and the retaining nut .

Therefore , it is possible to easily provide the lid member, and it is also possible to arrange the lid member at a position close to the connecting portion and the base end portion in the axial direction. Thereby, the lid member can suitably suppress corrosive bodies from reaching the connecting portion and the base end portion.

The lid member is preferably made of a resin that is elastically deformable between the tip and the retaining nut and has heat resistance against the heat of the corrosive body during operation of the injector.

In this case, the elastically deformed lid member can suitably close the gap between the tip and the retaining nut. Further, when the injector is operating, that is, when the engine is operating, the corrosive body may reach a high temperature, but even in such a case, the lid member is unlikely to melt or deteriorate. For these reasons, the lid member can more suitably prevent corrosive bodies from reaching the connecting portion and the base end portion.

According to the engine structure of the present invention, the durability of the injector can be further improved.

FIG. 1 is an enlarged sectional view of main parts showing the engine structure of Example 1. FIG. 2 is an enlarged sectional view of a main part showing an injector in the engine structure of the first embodiment. FIG. 3 is an enlarged cross-sectional view of main parts showing a nozzle, a retaining nut, etc. in the engine structure of the first embodiment. FIG. 4 is an enlarged sectional view of a main part showing an injector in the engine structure of the second embodiment. FIG. 5 is an enlarged sectional view of a main part showing an injector in the engine structure of Example 3.

Embodiments 1 to 3 embodying the present invention will be described below with reference to the drawings.

(Example 1)
As shown in FIG. 1, the engine structure of Example 1 is employed in a diesel engine 1. The diesel engine 1 includes a cylinder head 3, a cylinder block 5, and a plurality of injectors 7, as well as a common rail and a control device (not shown). The diesel engine 1 is installed in a vehicle such as an industrial vehicle or a passenger car. The engine structure of the first embodiment includes a cylinder head 3, a cylinder block 5, and each injector 7. The cylinder head 3 is an example of an "engine head" in the present invention. Note that in FIG. 1, one of each injector 7 is illustrated.

In this embodiment, the vertical direction of the diesel engine 1 is defined by the arrows shown in FIG. 2 and subsequent figures, the vertical direction of the diesel engine 1 is defined corresponding to FIG. 1. Note that each direction is an example, and the attitude of the diesel engine 1 can be changed as appropriate depending on the vehicle in which it is mounted.

The cylinder head 3 and cylinder block 5 are made of metal such as aluminum alloy. A plurality of cylinder bores 5a are formed in the cylinder block 5, and a piston (not shown) is provided in each cylinder bore 5a so as to be slidable in the vertical direction.

The cylinder head 3 is arranged above the cylinder block 5. By being fixed to the cylinder block 5, the cylinder head 3 forms a combustion chamber 9 in each cylinder bore 5a together with each piston. In addition, the cylinder head 3 is formed with a plurality of insertion holes 11, as well as a plurality of intake ports and exhaust ports (both not shown). In addition, in FIG. 1, one of the cylinder bore 5a, the combustion chamber 9, and the insertion hole 11 is illustrated.

Each insertion hole 11 is formed in the cylinder head 3 in correspondence to the number of each combustion chamber 9 and, by extension, each cylinder bore 5a. The insertion holes 11 communicate with each combustion chamber 9, and extend upward away from each combustion chamber 9 in the axial direction of the injector 7. Note that the axial direction of the injector 7 is parallel to the vertical direction of the diesel engine 1.

Each insertion hole 11 includes a first insertion hole 11a, a seat surface 11b, a second insertion hole 11c, a third insertion hole 11d, a fourth insertion hole 11e, a fifth insertion hole 11f, and a step 11g. have. As shown in FIGS. 2 and 3, the first insertion hole 11a is located at the lowest end of each insertion hole 11. As shown in FIGS. The first insertion hole 11a communicates with the combustion chamber 9 at its lower end and extends upward in the axial direction. The first insertion hole 11a is formed to have the smallest diameter among the insertion holes 11, and allows a first portion 731 of a nozzle 73, which will be described later, to be inserted therethrough.

The seat surface 11b is formed in an annular shape extending in the radial direction of the insertion hole 11, and has an inner circumferential edge 111 and an outer circumferential edge 112. The seat surface 11b is located above the first insertion hole 11a, and is continuous with the upper end of the first insertion hole 11a at an inner peripheral edge 111. The seat surface 11b extends in a planar shape in the radial direction of the insertion hole 11, increasing in diameter from the inner peripheral edge 111 toward the outer peripheral edge 112 than the first insertion hole 11a.

The second insertion hole 11c is coaxial with the first insertion hole 11a and has a larger diameter than the first insertion hole 11a. The second insertion hole 11c is located above the seat surface 11b. The second insertion hole 11c is continuous with the outer peripheral edge 112 of the seat surface 11b at its lower end, and extends upward in the axial direction.

The third insertion hole 11d is located above the second insertion hole 11c, and is coaxial with the second insertion hole 11c. The third insertion hole 11d is continuous with the upper end of the second insertion hole 11c at its lower end, and extends upward in the axial direction. Moreover, the diameter of the third insertion hole 11d gradually increases upward in the axial direction.

The fourth insertion hole 11e is located above the third insertion hole 11d, and is coaxial with the third insertion hole 11d. The lower end of the fourth insertion hole 11e is continuous with the upper end of the third insertion hole 11d, and extends upward in the axial direction. As shown in FIG. 1, the fifth insertion hole 11f is located above the fourth insertion hole 11e. The fifth insertion hole 11f is coaxial with the fourth insertion hole 11e, and extends upward in the axial direction. The fifth insertion hole 11f is formed to have the largest diameter among the insertion holes 11, and its upper side is open to the upper surface 3a of the cylinder head 3. The step 11g is located between the fourth insertion hole 11e and the fifth insertion hole 11f, and is connected to the upper end of the fourth insertion hole 11e and the lower end of the fifth insertion hole 11f.

Each injector 7 has a body 71, a nozzle 73, a retaining nut 75, a solenoid valve 77, and a mounting cap 79. The body 71 is made of metal such as carbon steel and extends in the axial direction. The body 71 has a shaft portion 71a, a main body portion 71b, and a fuel supply portion 71c. The shaft portion 71a is formed in a substantially cylindrical shape and extends downward in the axial direction from the main body portion 71b. The main body portion 71b is located above the shaft portion 71a and is integrated with the upper end of the shaft portion 71a. The main body portion 71b is formed into a substantially rectangular shape. The fuel supply section 71c is provided integrally with the main body section 71b. One end of the fuel pipe 13 is connected to the fuel supply section 71c. Although not shown, the other end of the fuel pipe 13 is connected to a common rail. Light oil as fuel is introduced into the common rail at a predetermined pressure.

The nozzle 73 is made of steel. As shown in FIG. 2, in the injector 7, the nozzle 73 is located below the body 71, more specifically, below the shaft portion 71a. The nozzle 73 has a substantially cylindrical shape that extends downward in the axial direction from the body 71, that is, toward the combustion chamber 9, and has a tip 73a, a base 73b, and a connecting portion 73c. There is. The distal end portion 73a, the proximal end portion 73b, and the connecting portion 73c are integrated.

The distal end portion 73a is formed to have a smaller diameter than the base end portion 73b. The distal end portion 73a is located closer to the combustion chamber 9 than the connecting portion 73c and the base end portion 73b. More specifically, the tip portion 73a includes a first portion 731, a second portion 732, and a tapered portion 733. The first portion 731 constitutes the lower end side of the tip portion 73a. The first portion 731 is formed to have a smaller diameter than the first insertion hole 11a, and extends vertically in the axial direction. That is, a plurality of injection holes 730 are formed at the lower end of the first portion 731 and at the tip of the first portion 731 on the combustion chamber 9 side. The second portion 732 constitutes the upper end side of the tip portion 73a. The second portion 732 is formed to have a larger diameter than the first portion 731, and is the portion having the largest diameter in the tip portion 73a.

The tapered portion 733 is located between the first portion 731 and the second portion 732 and is connected to the first portion 731 and the second portion 732. More specifically, the tapered portion 733 is connected to the upper end of the first portion 731 at its lower end. The tapered portion 733 extends while increasing its diameter from the lower end toward the upper end, and is connected to the lower end of the second portion 732 at the upper end.

The base end portion 73b is formed to have the largest diameter in the nozzle 73, and is located closer to the body 71 than the tip portion 73a and the connecting portion 73c. The base end portion 73b extends upward in the axial direction from the connecting portion 73c side toward the body 71 side. The base end portion 73b has a first contact surface 734 and a second contact surface 735 that are formed in a planar shape. The first contact surface 734 is located at the lower end of the base end portion 73b. The second contact surface 735 is located at the upper end of the base end portion 73b.

The connecting portion 73c is located between the distal end portion 73a and the proximal end portion 73b, and is connected to the distal end portion 73a and the proximal end portion 73b. More specifically, the connecting portion 73c is located between the second portion 732 of the distal end portion 73a and the first contact surface 734 of the proximal end portion 73b. The lower end of the connecting portion 73c is connected to the upper end of the second portion 732. The connecting portion 73c extends while increasing in diameter from the lower end toward the upper end, and is connected to the first contact surface 734 at the upper end. In this way, the connecting portion 73c is connected to the distal end portion 73a and the proximal end portion 73b.

Further, as shown in FIG. 3, in the nozzle 73, a plating layer 15 made of chrome plating is formed on the surface of the tip portion 73a, that is, on each surface of the first portion 731, the second portion 732, and the tapered portion 733. ing. Thereby, the plating layer 15 can protect the tip portion 73a from corrosive bodies. On the other hand, in the nozzle 73, the plating layer 15 is not formed on each surface of the base end portion 73b and the connecting portion 73c. Note that in FIG. 3, the plating layer 15 is illustrated in an exaggerated manner for ease of explanation.

As shown in FIGS. 2 and 3, the retaining nut 75 is formed in a multi-stage cylindrical shape extending in the axial direction, and has a first retaining hole 75a, a second retaining hole 75b, and a third retaining hole inside. 75c is formed. The first holding hole 75a is formed to have approximately the same diameter as the second portion 732 of the tip portion 73a. In other words, the first holding hole 75a is formed to have a larger diameter than the first portion 731 and the tapered portion 733 of the tip portion 73a. The second holding hole 75b is formed to have approximately the same diameter as the base end portion 73b. The third holding hole 75c is formed to have approximately the same diameter as the shaft portion 71a of the body 71. Further, inside the retaining nut 75, an abutted surface 75d is formed between the first holding hole 75a and the second holding hole 75b. The abutted surface 75d is formed in a planar shape.

The retaining nut 75 is inserted into the nozzle 73 and the shaft portion 71a from below and is fastened to the nozzle 73 and the shaft portion 71a. As a result, the retaining nut 75 holds the second portion 732 within the first holding hole 75a, the base end portion 73b within the second holding hole 75b, and the shaft portion 71a within the third holding hole 75c. keeping. Thus, in the injector 7, the body 71 and the nozzle 73 are coaxially fastened and integrated by the retaining nut 75. More specifically, in the nozzle 73, the base end portion 73b is coaxially fastened to the shaft portion 71a with the second contact surface 735 in contact with the lower end of the shaft portion 71a.

Further, by fastening the retaining nut 75 to the nozzle 73 and the shaft portion 71a, the first contact surface 734 of the base end portion 73b and the contact surface 75d of the retaining nut 75 face each other in the axial direction. state. In this state, the first contact surface 734 and the contact surface 75d are in contact with each other in the axial direction. Further, in the nozzle 73, the first portion 731 of the tip portion 73a is in a state of protruding further downward than the retaining nut 75. On the other hand, the second portion 732 and the tapered portion 733 are located within the retaining nut 75, that is, within the first holding hole 75a.

Further, as shown in FIG. 1, the injector 7 is formed with a shaft hole 7a, a first supply path 7b, and a second supply path 7c. The shaft hole 7a extends in the axial direction from the inside of the body 71 to the inside of the nozzle 73. As shown in FIG. 3, the shaft hole 7a communicates with each injection hole 730 within the first portion 731 of the nozzle 73. As shown in FIG. Further, a command piston 17 is provided within the shaft hole 7a. The command piston 17 switches communication and non-communication between the shaft hole 7a and each injection hole 730 by moving vertically within the shaft hole 7a. As shown in FIG. 1, the first supply path 7b extends from inside the body 71 to inside the nozzle 73 along the shaft hole 7a. The first supply path 7b is connected to the shaft hole 7a at its lower end. The second supply path 7c is connected to the first supply path 7b within the main body portion 71b of the body 71 and extends into the fuel supply section 71c.

The electromagnetic valve 77 is provided above the body 71, that is, above the main body portion 71b. The electromagnetic valve 77 operates the command piston 17 within the shaft hole 7a by being controlled by the control device. Thereby, the electromagnetic valve 77 switches between injecting fuel into the combustion chamber 9 from the injection hole 730 at a predetermined pressure and stopping fuel injection. In addition, in FIG. 1 and the like, in addition to the electromagnetic valve 77, the shaft hole 7a, the first supply path 7b, the second supply path 7c, and the command piston 17 are illustrated in a simplified manner for ease of explanation.

The mounting cap 79 accommodates the electromagnetic valve 77 therein and is fixed to the upper side of the main body portion 71b. Thereby, the mounting cap 79 fixes the solenoid valve 77 to the body 71.

Further, as shown in FIGS. 2 and 3, in this engine structure, a lid member 21 is provided between the tip 73a of the nozzle 73 and the retaining nut 75. More specifically, the lid member 21 is provided between the tapered portion 733 of the tip portion 73a and the first holding hole 75a of the retaining nut 75. Thus, in the injector 7, the lid member 21 is arranged at a position closer to the body 71 than the gasket 25 in the axial direction.

The lid member 21 is made of PTEF (polytetrafluoroethylene) and has an annular shape. Thereby, the lid member 21 is capable of elastic deformation and has heat resistance against the heat of corrosive bodies when each injector 7 is operated, that is, when the diesel engine 1 is operated. The lid member 21 is provided between the tapered portion 733 and the first holding hole 75a while being elastically deformed, thereby sealing the gap between the tapered portion 733 and the first holding hole 75a. Note that the lid member 21 may be formed of a resin such as PEEK (polyetheretherketone), or may be formed of a soft metal such as copper.

Further, in this engine structure, a gasket 25 is provided on the seat surface 11b of the insertion hole 11. The gasket 25 is made of copper and has an annular shape through which the tip 73a of the nozzle 73, more specifically, the first portion 731, can be inserted. As shown in FIG. 1, in this engine structure, each injector 7 is inserted into each insertion hole 11 from the fifth insertion hole 11f side with the nozzle 73 facing the combustion chamber 9 side. Thereby, in each injector 7, the first portion 731 of the nozzle 73 is inserted through the gasket 25 and into the first insertion hole 11a. In this way, the lower end of the first portion 731 including each injection hole 730 enters into the combustion chamber 9 . Note that when the first portion 731 is inserted into the gasket 25 and the first insertion hole 11a, there is a gap between the first portion 731 and the gasket 25 and between the first portion 731 and the first insertion hole 11a. , a slight gap inevitably occurs.

Further, in this engine structure, the retaining nut 75 and the gasket 25 face each other in the axial direction within the second insertion hole 11c. In this state, each injector 7 is fixed to the cylinder head 3 by the clamp 27. As a result, each injector 7 is in a state where it is pressed downwardly on the cylinder head 3 by the clamp 27, as shown by the white arrow in FIG. Thereby, the gasket 25 is sandwiched between the retaining nut 75 and the seat surface 11b in the axial direction, and seals between the retaining nut 75 and the seat surface 11b. Further, in each injector 7, a fuel pipe 13 is connected to a fuel supply section 71c of the body 71. Thereby, the second supply path 7c communicates with the fuel pipe 13.

In this way, by fixing each injector 7 in a state where it is pressed downward by the cylinder head 3 by the clamp 27, the first contact surface 734 of the nozzle 73 is fixed as shown by the white arrow in FIG. Through this, the base end portion 73b is in a state of pressing the retaining nut 75 downwardly of the cylinder head 3. Here, since the retaining nut 75 holds the gasket 25 between it and the seat surface 11b, stress from the seat surface 11b and, by extension, the cylinder head 3 acts on the retaining nut 75. As a result, stress from the retaining nut 75 acts on the first contact surface 734, as shown by the solid arrow in FIG. Further, the nozzle connecting portion 73c is connected to the base end portion 73b and the tip end portion 73a. Therefore, when the stress from the retaining nut 75 acts on the first contact surface 734, the tensile stress from the retaining nut 75 acts on the connecting portion 73c. Therefore, when the plating layer 15 is formed on each surface of the base end portion 73b and the connecting portion 73c, there is a concern that the plating layer 15 may crack due to stress from the retaining nut 75. In this regard, in this engine structure, since the plating layer 15 is not formed on each surface of the base end portion 73b and the connecting portion 73c, the above-mentioned concerns do not arise.

In this engine structure configured as described above, and thus in the diesel engine 1, the fuel in the common rail flows into the shaft hole 7a via the fuel pipe 13, the second supply path 7c, and the first supply path 7b. Furthermore, inside each combustion chamber 9, the air inside is compressed by a piston. In this state, the solenoid valve 77 in each injector 7 operates the command piston 17 to inject fuel into the combustion chamber 9 from each injection hole 730. As a result, in this engine structure, fuel is combusted within the combustion chamber 9, and power for driving the vehicle is generated.

As the fuel burns within the combustion chamber 9 in this manner, corrosive bodies are inevitably generated within the combustion chamber 9. Here, while each injector 7 is operating, that is, when the diesel engine 1 is operating, the corrosive body is high temperature combustion gas. Although most of the corrosive bodies generated within the combustion chamber 9 are discharged to the outside of the combustion chamber 9 through the exhaust port, some of the corrosive bodies are discharged from the combustion chamber 9 as shown by the broken line arrows in FIGS. 2 and 3. It flows from inside to the insertion hole 11 side through the gap between the first portion 731 and the first insertion hole 11a.

In this regard, in this engine structure, the gasket 25 seals between the retaining nut 75 and the seat surface 11b. For this reason, the corrosive bodies flowing to the insertion hole 11 side are prevented from being discharged to the outside of the cylinder head 3 through the gap between the injector 7 and the insertion hole 11.

Furthermore, in this engine structure, since the plating layer 15 is formed on the surface of the tip 73a of the nozzle 73, the tip 73a is prevented from being corroded by corrosive bodies flowing toward the insertion hole 11 side. .

Here, the corroded body that has flowed to the insertion hole 11 side passes through the gap between the first portion 731 of the tip portion 73a and the gasket 25, passes over the gasket 25, and enters the first holding hole 75a of the retaining nut 75. This means that they can be invaded. However, in this engine structure, the lid member 21 is provided between the tapered portion 733 and the first holding hole 75a, and the gap between the tapered portion 733 and the first holding hole 75a is sealed by the lid member 21. has been done. Therefore, the lid member 21 prevents corrosive bodies that have entered the first holding hole 75a beyond the gasket 25 from reaching the connecting portion 73c and the base end portion 73b. Thereby, in this engine structure, even if the plating layer 15 is not formed on each surface of the connecting portion 73c and the base end portion 73b, the connecting portion 73c and the base end portion 73b are difficult to corrode.

In addition, the corrosive bodies that were combustion gas are cooled when the diesel engine 1 is stopped or moved away from the combustion chamber 9. Therefore, the corrosive body may be condensed water produced by cooling the combustion gas. Therefore, if the corrosive body is condensed water, the corrosive body may adhere to the tip portion 73a or accumulate around the gasket 25. However, even in this case, the plating layer 15 prevents the tip 73a from being corroded by corrosive bodies, and the lid member 21 prevents the condensed water adhering to the tip 73a and the water accumulated around the gasket 25. Corrosive bodies are prevented from reaching the connecting portion 73c and the base end portion 73b.

Further, in this engine structure, since the lid member 21 prevents combustion gas as a corrosive body from reaching the connecting portion 73c and the base end portion 73b, in addition to the space between the connecting portion 73c and the retaining nut 75, Condensed water as a corrosive body is also less likely to form between the base end portion 73b and the retaining nut 75. In this respect as well, the connecting portion 73c and the base end portion 73b are less likely to corrode.

Thus, according to this engine structure, it is possible to suitably prevent the distal end 73a, the connecting section 73c, and the proximal end 73b of the nozzle 73 from being corroded by corrosive bodies.

Therefore, according to the engine structure of Example 1, the durability of each injector 7 can be further improved.

In particular, in this engine structure, the lid member 21 is provided between the tip portion 73a and the retaining nut 75, and between the tapered portion 733 and the first holding hole 75a. Therefore, in this engine structure, it is possible to easily provide the lid member 21, and it is also possible to arrange the lid member 21 at a position close to the connecting portion 73c and the base end portion 73b in the axial direction. ing. Thereby, the lid member 21 can suitably suppress corrosive bodies from reaching the connecting portion 73c and the base end portion 73b.

Further, the lid member is made of PTEF, and is elastically deformable and has heat resistance against the heat of the corrosive body. As a result, in this engine structure, the elastically deformed lid member 21 can suitably close the gap between the tapered portion 733 and the first holding hole 75a and seal the space between them. Further, when the diesel engine 1 is operating, the corrosive body, that is, the combustion gas, may reach a high temperature, but the lid member 21 is difficult to melt or deteriorate due to the heat of the corrosive body. In this respect as well, the lid member 21 can suitably prevent corrosive bodies from reaching the connecting portion 73c and the base end portion 73b.

(Example 2)
As shown in FIG. 4, in the engine structure of the second embodiment, a cover member 23 is provided in place of the cover member 21. As shown in FIG. Like the lid member 21, the lid member 23 is also made of PTFE. The lid member 23 is formed into a cylindrical shape through which the first portion 731 of the nozzle 73 can be inserted. Further, the upper end side of the lid member 23, that is, the portion on the tapered portion 733 side is expanded in diameter along the shape of the tapered portion 733.

The lid member 23 is inserted between the first portion 731 and the tapered portion 733. In this state, the retaining nut 75 is fastened to the nozzle 73 and the shaft portion 71a. In this way, the lid member 23 is provided between the tapered portion 733 and the first holding hole 75a while being elastically deformed, and seals the gap between the tapered portion 733 and the first holding hole 75a. The other components of this engine structure are similar to those of the engine structure of Example 1, and the same components are given the same reference numerals and detailed explanations regarding the configurations will be omitted.

This engine structure also makes it possible to achieve the same effect as the engine structure of the first embodiment. Further, in this engine structure, since the gap between the tapered portion 733 and the first holding hole 75a can be more preferably sealed by the lid member 23, it is possible to more effectively prevent corrosive bodies from reaching the connecting portion 73c and the base end portion 73b. This makes it possible to suppress this problem appropriately.

(Example 3)
As shown in FIG. 5, in the engine structure of the third embodiment, in the retaining nut 75, a retaining groove 750 is formed in the inner peripheral surface of the first retaining hole 75a. The holding groove 750 is provided on the inner circumferential surface of the first holding hole 75a at a location opposite to the second portion 732 of the nozzle 73, and circumferentially goes around the inner circumferential surface of the first holding hole 75a. . In this engine structure, the lid member 21 is provided within the holding groove 750. As a result, the retaining nut 75 is fastened to the nozzle 73 and the shaft portion 71a, so that the lid member 21 is provided between the second portion 732 and the holding groove 750 while being elastically deformed. Thus, in this engine structure, the lid member 21 seals the gap between the second portion 732 and the first holding hole 75a. The other components of this engine structure are similar to the engine structure of the first embodiment.

This engine structure also makes it possible to achieve the same effect as the engine structure of the first embodiment. In addition, in this engine structure, since the lid member 21 is provided in the retaining groove 750, it is protected against vibrations when the retaining nut 75 is fastened to the nozzle 73 and the shaft portion 71a, or when the diesel engine 1 is operating. , it becomes difficult for the lid member 21 to shift its position. In this respect as well, in this engine structure, the lid member 21 can suitably suppress corrosive bodies from reaching the connecting portion 73c and the base end portion 73b.

In the above, the present invention has been explained based on Examples 1 to 3, but the present invention is not limited to Examples 1 to 3, and can be applied with appropriate changes without departing from the spirit thereof. Needless to say.

For example, in the engine structures of Examples 1 to 3, the connecting portion 73c has a tapered shape whose diameter increases from the distal end portion 73a side toward the base end portion 73b side. However, the present invention is not limited thereto, and the connecting portion 73c may have a shape extending from the distal end portion 73a side toward the proximal end portion 73b side while keeping the diameter constant.

Further, in the engine structures of Examples 1 to 3, the plating layer 15 may be formed on each surface of the base end portion 73b and the connecting portion 73c of the nozzle 73.

Furthermore, although the engine structures of Examples 1 to 3 are employed in the diesel engine 1, the present invention is not limited to this, and may be employed in engines that use gasoline as fuel.

INDUSTRIAL APPLICATION This invention can be utilized for an industrial vehicle, a transportation vehicle, a passenger car, etc.

3...Cylinder head (engine head)
7... Injector 9... Combustion chamber 11... Insertion hole 11a... First insertion hole 11b... Seat surface 11c... Second insertion hole 15... Plating layer 21... Lid member 23... Lid member 25... Gasket 71... Body 73... Nozzle 73a... Tip part 73b... Base end part 73c... Connection part 75... Retaining nut 111... Inner peripheral edge 112... Outer peripheral edge 730... Injection hole 731... First part 732... Second part 733... Taper part

Claims (2)

An engine head that forms a combustion chamber, and an injector that is fixed to the engine head and injects fuel into the combustion chamber,
The engine head is formed with an insertion hole that communicates with the combustion chamber and extends in an axial direction away from the combustion chamber in the axial direction of the injector, and into which the injector is inserted;
The insertion hole includes a first insertion hole that communicates with the combustion chamber and extends in the axial direction, and a first insertion hole that is continuous with the first insertion hole at an inner peripheral edge and extends from the inner peripheral edge to the outer peripheral edge in a direction perpendicular to the axial direction. a seat surface whose diameter increases toward the seat surface; and a second insertion hole extending in the axial direction continuously from the outer peripheral edge of the seat surface;
The injector includes a body fixed to the engine head;
a nozzle located closer to the combustion chamber than the body, extending in the axial direction toward the combustion chamber and having an injection hole formed therein for injecting the fuel;
a retaining nut that is inserted through the body and the nozzle, fastens the body and the nozzle in the axial direction, and faces the seating surface in the axial direction;
In the engine structure, a gasket is provided between the engine head and the injector, and the gasket is sandwiched between the seat surface and the retaining nut.
The nozzle has a tip portion located on the combustion chamber side in the axial direction and in which the injection hole is formed;
a proximal end located on the body side in the axial direction, having a larger diameter than the distal end, facing and abutting the retaining nut in the axial direction, and fastened to the body by the retaining nut; Department and
a connecting portion located between the distal end and the proximal end and connected to the distal end and the proximal end;
A plating layer is formed on the surface of the tip portion to protect the tip portion from corrosive substances generated when the fuel burns in the combustion chamber,
Between the distal end portion and the retaining nut, a lid is provided at a position closer to the body than the gasket in the axial direction for suppressing the corrosive bodies from reaching the connecting portion and the base end portion. A member is provided ,
The tip portion has the injection hole formed therein, and a first portion that protrudes toward the combustion chamber side beyond the retaining nut and the gasket and extends into the first insertion hole;
a second portion located within the retaining nut, having a larger diameter than the first portion, and connecting to the connecting portion;
The retaining nut is located between the first part and the second part, and is connected to the first part and increases in diameter from the first part side toward the second part side. It has a tapered part that connects the two parts,
The engine structure is characterized in that the lid member is provided between the tapered portion and the retaining nut . The engine structure according to claim 1 , wherein the lid member is elastically deformable between the tip end and the retaining nut, and is made of a resin that has heat resistance to the heat of the corrosive body during operation of the injector. .

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