JP2021173235A - Engine structure - Google Patents

Abstract

To provide an engine structure which can improve the durability of an injector.SOLUTION: An engine structure comprises a cylinder head 3 as an engine head, and injectors 7. The cylinder head 3 is provided with an insertion hole 11 that extends in an axial direction while communicating with a combustion chamber 9 and allows each injector 7 to be inserted thereinto. The insertion hole 11 has a seat face 11b. Each of the injectors 7 has a body 71, a nozzle 73, and a retaining nut 75. Also, a gasket 25 is arranged between the cylinder head 3 and the retaining nut 75. The nozzle 73 has a tip part 73a, a base end part 73b and a connection part 73c. A plated layer 15 is formed on a surface of the tip part 73a. Also, between the tip part 73a and the retaining nut 75, a lid member 21 is arranged in a position being the body 71 side rather than the gasket 25 in an axial direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to an engine structure.

Patent Document 1 discloses a conventional engine structure. This engine structure includes an engine head and an injector. Although not specifically described in the 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. An 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 peripheral edge, and the diameter increases from the inner peripheral edge to the outer peripheral edge in a direction orthogonal to the axial direction. The second insertion hole extends axially continuously to the outer peripheral edge of the seat surface.

The injector has a nozzle and a retaining nut. Further, although not specifically described in the same document, the injector has a body fixed to the engine head. The nozzle is located closer to the combustion chamber than the body and extends axially toward the combustion chamber. The nozzle is formed with an injection hole for injecting fuel. The retaining nut is inserted between 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 insertion hole in the axial direction.

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

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

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

Japanese Unexamined Patent Publication No. 2016-180390

However, in the above-mentioned conventional engine structure, since the tip of the nozzle protrudes toward the combustion chamber side from the retaining nut and the gasket, the tip is exposed to the corrosive body. Further, it is inevitable that a part of the corrosive body generated in the combustion chamber passes between the tip of the nozzle and the gasket. Therefore, the nozzle is corroded by the corroded body. As a result, it is difficult to improve the durability of the nozzle and, by extension, the injector with this engine structure.

Therefore, it is conceivable to form a plating layer such as chrome plating on the surface of the nozzle, but the effect of the plating layer cannot be sufficiently exerted on each surface of the base end portion and the connection portion of the nozzle. This is because when the body and the nozzle are fastened with the retaining nut, the base end portion of the nozzle comes into contact with the retaining nut while facing the retaining nut in the axial direction. Then, in this state, the body is fixed to the engine head, so that the base end portion continues to press the retaining nut in the axial direction. Therefore, the stress from the retaining nut continues to act on the base end portion. Further, since the connecting portion of the nozzle is connected to the base end portion, the tensile stress from the retaining nut also acts on the connecting portion by fixing the body to the engine head. For these reasons, in the above engine structure, even if a plating layer is formed on each surface of the base end portion and the connection portion, cracks are likely to occur in the plating layer, and the connection portion is connected to the base end from the cracked portion. This is because the part is corroded.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object to be solved is to provide an engine structure capable of further improving 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 the axial direction away from the combustion chamber in the axial direction of the injector, through which the injector is inserted.
The insertion holes are continuous with the first insertion hole communicating with the combustion chamber and extending in the axial direction, and the first insertion hole at the inner peripheral edge, and from the inner peripheral edge to the outer peripheral edge in a direction orthogonal to the axial direction. It has a seat surface that expands in diameter toward the outside, and a second insertion hole that extends continuously in the axial direction on the outer peripheral edge of the seat surface.
The injector has a body fixed to the engine head and a body.
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 for injecting the fuel.
While being inserted through the body and the nozzle, the body and the nozzle are fastened in the axial direction, and the seat surface and the retaining nut facing each other in the axial direction are provided.
In an engine structure in which a gasket sandwiched between the seat surface and the retaining nut is provided between the engine head and the injector.
The nozzle is located on the combustion chamber side in the axial direction, and has a tip portion on which the injection hole is formed and a tip portion.
A base end located on the body side in the axial direction, having a diameter larger than that of the tip portion, abutting the retaining nut while facing the axial direction, and being fastened to the body by the retaining nut. Department and
It is located between the tip portion and the base end portion, and has a connecting portion that connects the tip portion and the base end portion.
A plating layer is formed on the surface of the tip portion to protect the tip portion from corrosive bodies generated by burning the fuel in the combustion chamber.
A lid that prevents the corrosive body from reaching the connecting portion and the base end portion between the tip portion and the retaining nut at a position on the body side of the gasket in the axial direction. It is characterized in that a member is provided.

In the engine structure of the present invention, since the plating layer is formed on the surface of the tip of the nozzle, it is possible to prevent the tip from being corroded by a corrosive body. Further, in this engine structure, a lid member is provided between the tip portion and the retaining nut at a position on the body side of the gasket in the axial direction of the injector. As a result, the lid member prevents the corrosive body from reaching the connecting portion and the proximal end portion by closing the gap between the tip portion and the retaining nut. Therefore, even if the plating layer is not formed on each surface of the connecting portion and the proximal end portion, the connecting portion and the proximal end portion are less likely to be corroded. Further, in this engine structure, the lid member suppresses the combustion gas as a corrosive body from reaching the connection portion and the base end portion, so that the space between the connection portion and the retaining nut and the base end portion and the retaining nut are prevented. Condensed water as a corrosive body is less likely to occur between and. In this respect as well, in this engine structure, the connection portion and the base end portion are less likely to be corroded. Thus, according to this engine structure, it is possible to preferably prevent the tip portion, the connection portion, and the base end portion from being corroded by the corrosive body.

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

At the tip, an injection hole is formed, and a first portion that protrudes toward the combustion chamber side of the retaining nut and gasket and extends into the first insertion hole, and a first portion located in the retaining nut and more than the first portion. It has a large diameter and is located between the second part that connects to the connection part and the first part and the second part in the retaining nut, and is connected to the first part from the first part side to the second part side. It may have a tapered portion that expands in diameter toward and connects to the second portion. The lid member is preferably provided between the tapered portion and the retaining nut.

In this case, the lid member can be easily provided, and the lid member can be arranged at a position close to the connecting portion and the base end portion in the axial direction. As a result, the lid member can suitably prevent the corrosive body from reaching the connecting portion and the proximal 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 to 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 portion and the retaining nut. Further, when the injector is operated, that is, when the engine is operated, the corrosive body may become hot, but even in such a case, the lid member is less likely to melt or deteriorate. For these reasons, the lid member can more preferably prevent the corrosive body from reaching the connecting portion and the proximal 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 cross-sectional view of a main part showing the engine structure of the first embodiment. FIG. 2 is an enlarged cross-sectional view of a main part showing an injector according to the engine structure of the first embodiment. FIG. 3 is an enlarged cross-sectional view of a main part showing a nozzle, a retaining nut, and the like according to the engine structure of the first embodiment. FIG. 4 is an enlarged cross-sectional view of a main part showing an injector according to the engine structure of the second embodiment. FIG. 5 is an enlarged cross-sectional view of a main part showing an injector according to the engine structure of the third embodiment.

Hereinafter, Examples 1 to 3 embodying the present invention will be described with reference to the drawings.

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

In this embodiment, the vertical direction of the diesel engine 1 is defined by the arrows shown in FIG. Then, in FIGS. 2 and 2, the vertical direction of the diesel engine 1 is defined corresponding to FIG. It should be noted that each direction is an example, and the posture of the diesel engine 1 can be appropriately changed according to the vehicle on which the diesel engine 1 is mounted.

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

The cylinder head 3 is arranged above the cylinder block 5. By fixing the cylinder head 3 to the cylinder block 5, a combustion chamber 9 is formed in each cylinder bore 5a together with each piston. Further, the cylinder head 3 is formed with a plurality of insertion holes 11 and a plurality of intake ports and exhaust ports (all of which are not shown). Note that FIG. 1 illustrates one of the cylinder bore 5a, the combustion chamber 9, and the insertion hole 11.

Each insertion hole 11 is formed in the cylinder head 3 corresponding 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 in the axial direction of the injector 7 so as to move away from each combustion chamber 9. The axial direction of the injector 7 is parallel to the vertical direction of the diesel engine 1.

Each insertion hole 11 has a first insertion hole 11a, a seating 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 lowermost end of each insertion hole 11. The first insertion hole 11a communicates with the combustion chamber 9 at the lower end and extends upward in the axial direction. The first insertion hole 11a is formed to have the smallest diameter in each insertion hole 11, and is capable of inserting the first portion 731 of the nozzle 73, which will be described later.

The seat surface 11b is formed in an annular shape extending in the radial direction of the insertion hole 11, and has an inner peripheral edge 111 and an outer peripheral 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 the inner peripheral edge 111. The seat surface 11b extends from the inner peripheral edge 111 toward the outer peripheral edge 112 in a plane in the radial direction of the insertion hole 11 while having a diameter larger than that of 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 the 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 the lower end, and extends upward in the axial direction. Further, 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 fourth insertion hole 11e is continuous with the upper end of the third insertion hole 11d at the lower end, 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 in each insertion hole 11, and the 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 a 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 from the main body portion 71b in the axial direction. 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 71b is formed in a substantially rectangular shape. The fuel supply unit 71c is integrally provided with the main body unit 71b. One end side of the fuel pipe 13 is connected to the fuel supply unit 71c. Although not shown, the other end of the fuel pipe 13 is connected to the 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 on the lower side of the body 71, more specifically, on the lower side of the shaft portion 71a. The nozzle 73 has a substantially cylindrical shape extending axially downward from the body 71, that is, toward the combustion chamber 9 side, and has a tip portion 73a, a base end portion 73b, and a connection portion 73c. There is. The tip end portion 73a, the base end portion 73b, and the connection portion 73c are integrated.

The tip portion 73a is formed to have a smaller diameter than the base end portion 73b. The tip portion 73a is located closer to the combustion chamber 9 than the connection portion 73c and the base end portion 73b. More specifically, the tip portion 73a is composed of 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 diameter smaller than that of 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 the tip of the first portion 731, which are 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 at 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 the lower end. The tapered portion 733 extends while increasing in diameter from the lower end to 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 formed in a plane 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 connection portion 73c is located between the tip end portion 73a and the base end portion 73b, and is connected to the tip end portion 73a and the base end portion 73b. More specifically, the connecting portion 73c is located between the second portion 732 of the tip portion 73a and the first contact surface 734 of the proximal end portion 73b. The connecting portion 73c is connected to the upper end of the second portion 732 at the lower end. The connecting portion 73c extends while increasing in diameter from the lower end to 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 tip end portion 73a and the base 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 the surfaces of the first portion 731, the second portion 732, and the tapered portion 733. ing. As a result, the plating layer 15 can protect the tip portion 73a from the corrosive body. On the other hand, in the nozzle 73, the plating layer 15 is not formed on the surfaces of the base end portion 73b and the connecting portion 73c. In FIG. 3, the plating layer 15 is exaggerated for the sake of simplicity.

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 holding hole 75a, a second holding hole 75b, and a third holding hole inside. 75c and the like are formed. The first holding hole 75a is formed to have substantially 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 substantially the same diameter as the base end portion 73b. The third holding hole 75c is formed to have substantially the same diameter as the shaft portion 71a of the body 71. Further, inside the retaining nut 75, a contact surface 75d is formed between the first holding hole 75a and the second holding hole 75b. The contacted surface 75d is formed in a flat shape.

The retaining nut 75 is fastened to the nozzle 73 and the shaft portion 71a while being inserted into the nozzle 73 and the shaft portion 71a from the lower side. As a result, the retaining nut 75 holds the second portion 732 in the first holding hole 75a, holds the base end portion 73b in the second holding hole 75b, and holds the shaft portion 71a in the third holding hole 75c. keeping. In this way, 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 in a state where the second contact surface 735 is 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 contacted surface 75d of the retaining nut 75 face each other in the axial direction. It becomes a state. Then, in this state, the first contact surface 734 and the contact surface 75d are in axial contact with each other. Further, in the nozzle 73, at the tip portion 73a, the first portion 731 is in a state of protruding downward from the retaining nut 75. On the other hand, the second portion 732 and the tapered portion 733 are located in the retaining nut 75, that is, in 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 axially 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 in the first portion 731 of the nozzle 73. A command piston 17 is provided in the shaft hole 7a. The command piston 17 switches between communication and non-communication between the shaft hole 7a and each injection hole 730 by moving in the vertical direction in the shaft hole 7a. As shown in FIG. 1, the first supply path 7b extends from the inside of the body 71 to the inside of the nozzle 73 along the shaft hole 7a. The first supply path 7b is connected to the shaft hole 7a at the lower end. The second supply path 7c extends into the fuel supply section 71c while being connected to the first supply path 7b in the main body portion 71b of the body 71.

The solenoid valve 77 is provided on the upper side of the body 71, that is, on the upper side of the main body portion 71b. The solenoid valve 77 operates the command piston 17 in the shaft hole 7a by being controlled by the control device. As a result, the solenoid valve 77 switches between a case where fuel is injected into the combustion chamber 9 from the injection hole 730 at a predetermined pressure and a case where fuel injection is stopped. In FIG. 1 and the like, in addition to the solenoid valve 77, the shaft hole 7a, the first supply path 7b, the second supply path 7c, and the command piston 17 are shown in a simplified manner for easy explanation.

The mounting cap 79 is fixed to the upper side of the main body 71b while accommodating the solenoid valve 77 inside. As a result, 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 portion 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. In this way, 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 is formed in an annular shape. As a result, the lid member 21 can be elastically deformed and has heat resistance to the heat of the corrosive body when each injector 7 is operated, that is, when the diesel engine 1 is operated. The lid member 21 is elastically deformed and is provided between the tapered portion 733 and the first holding hole 75a to seal the gap between the tapered portion 733 and the first holding hole 75a. 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 portion 73a of the nozzle 73, more specifically, the first portion 731 can be inserted. Then, 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. As a result, in each injector 7, the first portion 731 of the nozzle 73 is inserted into the first insertion hole 11a while being inserted into the gasket 25. In this way, the lower end of the first portion 731, including each injection hole 730, penetrates into the combustion chamber 9. In the state where the first portion 731 is inserted through the gasket 25 and the first insertion hole 11a, there is only a small amount between the first portion 731 and the gasket 25 and the first portion 731 first insertion hole 11a. There are inevitably gaps.

Further, in this engine structure, the retaining nut 75 and the gasket 25 face each other in the axial direction in the second insertion hole 11c. Then, in this state, each injector 7 is fixed to the cylinder head 3 by the clamp 27. As a result, as shown by the white arrow in FIG. 1, each injector 7 is pressed toward the lower side of the cylinder head 3 by the clamp 27. As a result, the gasket 25 is axially sandwiched between the retaining nut 75 and the seat surface 11b, and seals between the retaining nut 75 and the seat surface 11b. Further, in each injector 7, the fuel pipe 13 is connected to the fuel supply unit 71c of the body 71. As a result, the second supply path 7c communicates with the fuel pipe 13.

In this way, each injector 7 is fixed in a state of being pressed downward of the cylinder head 3 by the clamp 27, and as shown by the white arrow in FIG. 2, the nozzle 73 has a first contact surface 734. Through this, the base end portion 73b is in a state of pressing the retaining nut 75 toward the lower side of the cylinder head 3. Here, since the retaining nut 75 sandwiches the gasket 25 with 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, as shown by the solid arrow in FIG. 3, the stress from the retaining nut 75 acts on the first contact surface 734. Further, the nozzle connecting portion 73c is connected to the base end portion 73b and the tip end portion 73a. Therefore, the stress from the retaining nut 75 acts on the first contact surface 734, so that the tensile stress from the retaining nut 75 acts on the connecting portion 73c. Therefore, when the plating layer 15 is formed on the surfaces of the base end portion 73b and the connection portion 73c, there is a concern that the plating layer 15 may be cracked due to the stress from the retaining nut 75. In this respect, in this engine structure, since the plating layer 15 is not formed on the surfaces of the base end portion 73b and the connecting portion 73c, the above-mentioned concerns do not occur.

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

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

In this respect, in this engine structure, the gasket 25 seals between the retaining nut 75 and the seat surface 11b. Therefore, it is prevented that the corrosive body distributed on the insertion hole 11 side is discharged to the outside of the cylinder head 3 through the gap between the injector 7 and the insertion hole 11.

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

Here, the corrosive 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, and thus exceeds the gasket 25 and enters the first holding hole 75a of the retaining nut 75. It can invade. However, in this engine structure, a lid member 21 is provided between the tapered portion 733 and the first holding hole 75a, and the lid member 21 seals the gap between the tapered portion 733 and the first holding hole 75a. Has been done. Therefore, the lid member 21 prevents the corrosive body that has entered the first holding hole 75a beyond the gasket 25 from reaching the connecting portion 73c and the proximal end portion 73b. As a result, in this engine structure, even if the plating layer 15 is not formed on the surfaces of the connecting portion 73c and the proximal end portion 73b, the connecting portion 73c and the proximal end portion 73b are less likely to be corroded.

Further, the corrosive body that was the combustion gas is cooled when the diesel engine 1 is stopped or when the diesel engine 1 is moved away from the combustion chamber 9. Therefore, the corrosive body may be condensed water generated by cooling the combustion gas. Therefore, when the corrosive body is condensed water, the corrosive body adheres to the tip portion 73a or is stored around the gasket 25. However, even in this case, the plating layer 15 prevents the tip portion 73a from being corroded by the corrosive body, and the lid member 21 is stored around the condensed water and the gasket 25 adhering to the tip portion 73a. It prevents the corrosive body from reaching the connecting portion 73c and the proximal end portion 73b.

Further, in this engine structure, the lid member 21 suppresses the combustion gas as a corrosive body from reaching the connecting portion 73c and the proximal end portion 73b, thereby preventing the combustion gas as a corrosive body from reaching the connecting portion 73c and the retaining nut 75, as well as between the connecting portion 73c and the retaining nut 75. Condensed water as a corrosive body is less likely to occur between the base end portion 73b and the retaining nut 75. Also in this respect, the connecting portion 73c and the proximal end portion 73b are less likely to corrode.

Thus, according to this engine structure, it is possible to preferably prevent the tip portion 73a, the connection portion 73c, and the base end portion 73b of the nozzle 73 from being corroded by the corrosive body.

Therefore, according to the engine structure of the first embodiment, 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, the lid member 21 can be easily provided, and the lid member 21 can be arranged at a position close to the connecting portion 73c and the base end portion 73b in the axial direction. ing. As a result, the lid member 21 can suitably prevent the corrosive body from reaching the connecting portion 73c and the proximal end portion 73b.

Further, the lid member is made of PTFE, is elastically deformable, and has heat resistance to the heat of the corrosive body. As a result, in this engine structure, the elastically deformed lid member 21 can appropriately close the gap between the tapered portion 733 and the first holding hole 75a and seal the gap between them. Further, when the diesel engine 1 is operated, the corrosive body, that is, the combustion gas may become hot, but the lid member 21 is less likely to be melted or deteriorated by the heat of the corrosive body. In this respect as well, the lid member 21 can suitably prevent the corrosive body from reaching the connecting portion 73c and the proximal end portion 73b.

(Example 2)
As shown in FIG. 4, in the engine structure of the second embodiment, the lid member 23 is provided instead of the lid member 21. Like the lid member 21, the lid member 23 is also made of PTFE. The lid member 23 is formed in 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. Then, 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. Other configurations in this engine structure are the same as those in the engine structure of the first embodiment, and the same configurations are designated by the same reference numerals and detailed description of the configurations will be omitted.

This engine structure also makes it possible to perform the same operation as that of the engine structure of the first embodiment. Further, in this engine structure, the lid member 23 can more preferably seal the gap between the tapered portion 733 and the first holding hole 75a, so that the corrosive body reaches the connecting portion 73c and the proximal end portion 73b. It is possible to suppress it suitably.

(Example 3)
As shown in FIG. 5, in the engine structure of the third embodiment, the retaining groove 750 is recessed in the inner peripheral surface of the first holding hole 75a in the retaining nut 75. The holding groove 750 is provided at a position facing the second portion 732 of the nozzle 73 on the inner peripheral surface of the first holding hole 75a, and goes around the inner peripheral surface of the first holding hole 75a in the circumferential direction. .. In this engine structure, the lid member 21 is provided in 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. Other configurations in this engine structure are the same as those in the engine structure of the first embodiment.

This engine structure also makes it possible to perform the same operation as that of the engine structure of the first embodiment. Further, in this engine structure, since the lid member 21 is provided in the holding groove 750, the retaining nut 75 may be fastened to the nozzle 73 and the shaft portion 71a, or the diesel engine 1 may be vibrated during operation. , The lid member 21 is less likely to be misaligned. In this respect as well, in this engine structure, the lid member 21 can suitably prevent the corrosive body from reaching the connecting portion 73c and the proximal end portion 73b.

In the above, the present invention has been described with reference to Examples 1 to 3, but the present invention is not limited to the above Examples 1 to 3, and can be appropriately modified and applied without departing from the spirit thereof. Needless to say.

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

Further, in the engine structure 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.

Further, the engine structures of Examples 1 to 3 are adopted in the diesel engine 1, but the present invention is not limited to this, and may be adopted in an engine using gasoline as a fuel.

The present invention can be used for industrial vehicles, transportation vehicles, passenger cars, and the like.

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 portion 73b ... Base end portion 73c ... Connection portion 75 ... Retaining nut 111 ... Inner peripheral edge 112 ... Outer peripheral edge 730 ... Injection hole 731 ... First part 732 ... Second part 733 ... Tapered part

Claims (3)

An engine head forming a combustion chamber and an injector fixed to the engine head and injecting fuel into the combustion chamber are provided.
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 in the axial direction of the injector, through which the injector is inserted.
The insertion holes are continuous with the first insertion hole communicating with the combustion chamber and extending in the axial direction, and the first insertion hole at the inner peripheral edge, and from the inner peripheral edge to the outer peripheral edge in a direction orthogonal to the axial direction. It has a seat surface that expands in diameter toward the outside, and a second insertion hole that extends continuously in the axial direction on the outer peripheral edge of the seat surface.
The injector has a body fixed to the engine head and a body.
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 for injecting the fuel.
While being inserted through the body and the nozzle, the body and the nozzle are fastened in the axial direction, and the seat surface and the retaining nut facing each other in the axial direction are provided.
In an engine structure in which a gasket sandwiched between the seat surface and the retaining nut is provided between the engine head and the injector.
The nozzle is located on the combustion chamber side in the axial direction, and has a tip portion on which the injection hole is formed and a tip portion.
A base end located on the body side in the axial direction, having a diameter larger than that of the tip portion, abutting the retaining nut while facing the axial direction, and being fastened to the body by the retaining nut. Department and
It is located between the tip portion and the base end portion, and has a connecting portion that connects the tip portion and the base end portion.
A plating layer is formed on the surface of the tip portion to protect the tip portion from corrosive bodies generated by burning the fuel in the combustion chamber.
A lid that prevents the corrosive body from reaching the connecting portion and the base end portion between the tip portion and the retaining nut at a position on the body side of the gasket in the axial direction. An engine structure characterized by being provided with members. The tip portion includes a first portion in which the injection hole is formed and the retaining nut and the gasket project toward the combustion chamber side and extend into the first insertion hole.
A second portion located in the retaining nut, having a diameter larger than that of the first portion, and connecting to the connecting portion,
The first portion is located in the retaining nut between the first portion and the second portion, and the diameter is increased from the first portion side to the second portion side while being connected to the first portion. It has a tapered part that connects to two parts,
The engine structure according to claim 1, wherein the lid member is provided between the tapered portion and the retaining nut. The first or second claim, wherein the lid member is made of a resin that is elastically deformable between the tip portion and the retaining nut and has heat resistance to the heat of the corrosive body when the injector is operated. Engine structure.

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