CN112204242B - Fuel injection valve - Google Patents

Abstract

In a fuel injection valve for injecting fuel and water from an injection hole into a combustion chamber in a cylinder of a marine diesel engine, a first water injection check valve for opening and closing a first water injection passage is disposed on the injection hole side, and a second water injection check valve for opening and closing a second water injection passage is disposed on the opposite side of the injection hole, with respect to a needle spring for urging the needle to the injection hole side to close a tip end oil passage leading to the fuel oil passage and the injection hole so as to be openable and closable. The water in the first water injection passage is injected into the fuel oil passage from the position where the first water injection check valve is disposed, and the water in the second water injection passage is injected into the fuel oil passage from the position where the second water injection check valve is disposed.

Description

Fuel injection valve

Technical Field

The present invention relates to a fuel injection valve applied to fuel injection of a marine diesel engine mounted on a ship.

Background

In the field of ships, it has been effective to inject fuel and water from the same fuel injection valve into a combustion chamber in a cylinder as a method for reducing nitrogen oxides (NOx) generated during in-gate combustion of a marine diesel engine. For example, patent document 1 proposes a fuel injection valve in which high-pressure water is injected into fuel in a fuel oil passage from a water passage in a valve body through a water injection check valve, and the fuel and the water are injected into a combustion chamber in a cylinder in three stages in a fuel-water-fuel order in one-cycle injection.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 6-66217

Technical problem to be solved by the invention

However, in the water injection technique of alternately injecting fuel and water into the combustion chamber in the cylinder as described above, from the viewpoint of improving fuel economy performance and NOx reduction performance of the marine diesel engine, it is preferable that the one-cycle injection of fuel and water into the combustion chamber be four-stage or more injection in which a plurality of fuel layers and a water injection layer are alternately arranged. The fuel layer is a layer of fuel formed in the fuel oil passage when the injection is performed for one cycle. The water injection layer is a layer of water injected into the fuel layer in the fuel oil passage.

In such injection of the fuel bed and the water injection layer in four stages or more, the amount of fuel in the fuel bed sandwiched between the water injection layers (hereinafter referred to as the amount of fuel between the water injection layers) in the fuel oil path is a very important factor in terms of securing the stability of the marine diesel engine. That is, when the fuel layer of the first layer (first fuel layer), the water injection layer of the first layer (first water injection layer), the fuel layer of the second layer (second fuel layer), the water injection layer of the second layer (second water injection layer), and the fuel layer of the third layer (third fuel layer) are injected in this order from the injection holes of the fuel injection valve in the injection of the combustion chamber in one cycle, it is preferable that the amount of fuel of the second fuel layer (the amount of fuel between the water injection layers) sandwiched between the first water injection layer and the second water injection layer and the injection amount of fuel per one cycle (hereinafter, referred to as fuel injection amount) into the combustion chamber are in a predetermined ratio. In order to satisfy this condition, a water injection check valve for a water passage for injecting water to become the first water injection layer into the fuel oil passage and a water injection check valve for a water passage for injecting water to become the second water injection layer are generally disposed separately from each other so that the amount of fuel between the water injection layers is appropriate.

However, in the conventional fuel injection valve exemplified in patent document 1, when the water injection check valves are separated from each other and incorporated in the fuel injection valve so that the amount of fuel between the water injection layers satisfies the above-described condition, the fuel injection valve is often increased in size (elongated) in the longitudinal direction.

In order to secure the distance between the water injection check valves, a method may be considered in which the water injection check valve corresponding to the first water injection layer is incorporated in the fuel injection valve, and the water injection check valve corresponding to the second water injection layer is externally attached to the fuel injection valve via a pipe or the like. However, in this method, the joint strength (mechanical reliability) between the fuel injection valve and the externally-mounted water injection check valve may be reduced by vibration of the cylinder, the fuel injection valve, and the like that is generated in association with the operation of the marine diesel engine. Therefore, it is preferable that each of the water injection check valves is incorporated in the fuel injection valve.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel injection valve capable of ensuring a preferable distance between the built-in water injection check valves and suppressing an increase in the size of the structure.

Means for solving the problems

In order to solve the above problems and achieve the object, a fuel injection valve according to the present invention injects fuel and water from an injection hole into a combustion chamber in a cylinder of a marine diesel engine, and includes: a fuel oil passage through which the fuel pumped from a fuel injection pump flows; a tip oil passage having one end opening to the fuel oil passage and the other end opening to the nozzle hole; a needle valve that closes the tip oil passage in an openable and closable manner; a needle valve spring that applies a force to the needle valve toward the orifice side to close the top oil passage; a first water injection passage for injecting water to a predetermined position of the fuel oil passage; a second water injection passage for injecting water into the fuel oil passage at a position upstream of the first water injection passage in a direction in which the fuel is pumped; a first water injection check valve disposed closer to the nozzle than the needle spring and closing the first water injection passage so as to be openable and closable; and a second water injection check valve that is disposed on a side opposite to the injection hole with reference to the needle spring and closes the second water injection passage so as to be openable and closable, wherein water in the first water injection passage is injected into the fuel oil passage from a position where the first water injection check valve is disposed, and water in the second water injection passage is injected into the fuel oil passage from a position where the second water injection check valve is disposed.

In the above-described invention, the first water injection check valve and the second water injection check valve of the fuel injection valve according to the present invention are coaxially arranged in a direction of a longitudinal central axis of the fuel injection valve.

In the above-described invention, the first water injection passage of the fuel injection valve according to the present invention has an annular water injection passage formed in an annular shape surrounding the first water injection check valve.

In the above-described invention, the fuel passage of the fuel injection valve according to the present invention is disposed so as to pass through a longitudinal central axis of the fuel injection valve.

In the above-described invention, the fuel passage of the fuel injection valve according to the present invention is disposed at a position radially distant from a longitudinal center axis of the fuel injection valve.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the following effects can be achieved: the preferable spacing distance between the built-in water injection check valves can be ensured, and the structure can be inhibited from being enlarged.

Drawings

Fig. 1 is a schematic cross-sectional view showing a configuration example of a fuel injection valve according to a first embodiment of the present invention.

Fig. 2 is a schematic sectional view of the fuel injection valve shown in fig. 1 taken along line a-a.

Fig. 3 is a schematic sectional view of the fuel injection valve shown in fig. 1 taken along line B-B.

Fig. 4 is a schematic cross-sectional view showing a configuration example of a fuel injection valve according to a second embodiment of the present invention.

Fig. 5 is a schematic cross-sectional view showing a configuration example of a fuel injection valve according to a second embodiment of the present invention, as viewed from another point of view.

Fig. 6 is a schematic cross-sectional view of the fuel injection valve shown in fig. 4 taken along line C-C.

Detailed Description

Hereinafter, preferred embodiments of the fuel injection valve according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the present embodiment. Note that the drawings are schematic, and the dimensional relationship, the ratio, and the like of the elements may be different from those in reality. The drawings may include portions having different dimensional relationships and ratios from each other. In the drawings, the same components are denoted by the same reference numerals.

(first embodiment)

First, the structure of the fuel injection valve according to the first embodiment of the present invention will be described. Fig. 1 is a schematic cross-sectional view showing a configuration example of a fuel injection valve according to a first embodiment of the present invention. Fig. 2 is a schematic sectional view of the fuel injection valve shown in fig. 1 taken along line a-a. Fig. 3 is a schematic sectional view of the fuel injection valve shown in fig. 1 taken along line B-B. In fig. 1, the axial direction F1 is the direction of the longitudinal center axis of the fuel injection valve 100. In the first embodiment, for convenience of explanation of the configuration of the fuel injection valve 100, the positive side in the axial direction F1 is set to the tip side of the fuel injection valve 100, and the negative side in the axial direction F1 is set to the rear end side of the fuel injection valve 100. The radial direction F2 is the radial direction of the fuel injection valve 100, and is the direction perpendicular to the longitudinal center axis of the fuel injection valve 100.

The fuel injection valve 100 according to the first embodiment is attached to a cylinder (not shown) of a marine diesel engine, and injects (for example, injects in layers) fuel pressure-fed from a fuel injection pump (not shown) and water pressure-fed from a water injection pump (not shown) sequentially into a combustion chamber in the cylinder. As shown in fig. 1, the fuel injection valve 100 includes a nozzle 1 located at a tip end, an injection valve main body 11 located at a rear end side of the nozzle 1, and an injection valve main body 40 located at a rear end side of the injection valve main body 11. The nozzle 1 and the injection valve body 11 are fastened from the outer periphery by a nut-shaped nozzle fastening fitting 10, and thereby are fixed in a state of being coupled in the axial direction F1. The injection valve body 11 and the injection valve body 40 on the rear end side are fastened from the outer periphery by the nut-shaped valve body fastening metal fitting 30, and are thereby fixed in a state of being coupled in the axial direction F1.

Nozzle 1 constitutes the tip portion of fuel injection valve 100. As shown in fig. 1, a needle valve housing portion 2 having a hole shape elongated in the axial direction F1 is provided in the nozzle 1. A needle valve 6 is slidably accommodated in the needle valve accommodating portion 2, and the needle valve 6 openably blocks communication between the fuel passage of the fuel injection valve 100 and the injection hole 4. The needle valve 6 is provided with a needle valve internal flow path 7 that is long in the axial direction F1. A reservoir 3 is formed between the tip end side of the needle valve housing 2 and the tip end side of the needle valve 6. A communication hole 8 for communicating the needle valve internal oil passage 7 with the reservoir 3 is provided at the tip end of the needle valve 6. Further, the nozzle 1 is provided with a nozzle hole 4 and a tip oil passage 5 on the tip side. One end of the tip end oil passage 5 leads to a fuel oil passage of the fuel injection valve 100 (specifically, a needle valve internal oil passage 7 that is a part of the fuel oil passage of the fuel injection valve 100). The other end of the top oil passage 5 leads to the nozzle hole 4.

The injection valve main body 11 constitutes an intermediate portion between the nozzle 1 on the tip end side and the injection valve main body 40 on the rear end side. As shown in fig. 1, a check valve housing portion 12 having a hole shape elongated in the axial direction F1 is provided in the injection valve main body 11. A water injection check valve 20 corresponding to the first water injection path of the fuel injection valve 100 is housed in the check valve housing portion 12. In the first embodiment, the first water injection passage is a passage for injecting water to a predetermined position (the first water injection position P1 shown in fig. 1) of the fuel oil passage of the fuel injection valve 100.

The water injection check valve 20 is a check valve (first water injection check valve) that openably closes a first water injection passage of the fuel injection valve 100. As shown in fig. 1, the water injection check valve 20 is composed of a valve body 21, a valve seat 24, a check valve spring 26, and a valve body support portion 27, and is disposed on the injection hole 4 side of a needle spring 50 described later.

As shown in fig. 1, the valve body 21 has a pressure receiving portion 23 that receives the pressure of water from the first water injection passage, and is slidably accommodated in a valve body supporting portion 27. As shown in fig. 1 and 2, the pressure receiving portion 23 is formed annularly along the outer periphery of the valve body 21 in the vicinity of the tip end portion thereof. Further, an in-valve-body oil passage 22, which is a part of the fuel oil passage of the fuel injection valve 100, is provided in the valve body 21. As shown in fig. 1, the valve seat 24 is fixed to the distal end portion of the valve body support portion 27 by fastening or the like. A valve seat internal oil passage 25 that is a part of the fuel oil passage of the fuel injection valve 100 is provided in the valve body 24. As shown in fig. 1, the check valve spring 26 is disposed between the rear end portion of the valve body 21 and the valve body support portion 27. The check valve spring 26 applies a biasing force applied to the valve seat 24 side to the valve element 21. The water injection check valve 20 presses the valve body 21 against the valve seat 24 by the biasing force of the check valve spring 26, thereby openably blocking communication between the fuel oil passage of the fuel injection valve 100 and the first water injection passage.

In the first embodiment, the water injection check valve 20 has both the function as the check valve described above and the function as a push rod for transmitting the urging force of the needle spring 50 to the needle 6. In detail, as shown in fig. 1, the water injection check valve 20 is interposed between the needle valve 6 and the needle valve spring 50. For example, the water injection check valve 20 is in a state in which the needle spring 50 is supported by the rear end portion of the valve body support portion 27 and the tip end portion of the valve seat 24 is pressed against the rear end portion of the needle 6. The water injection check valve 20 is slidable in the axial direction F1 in the check valve housing portion 12, and presses the needle valve 6 toward the tip oil passage 5 by the biasing force of the needle valve spring 50. The water injection check valve 20 slides in a direction against the biasing force of the needle spring 50 (in a direction to compress the needle spring 50) together with the needle 6, which slides in a direction away from the tip oil passage 5 by the pressure of the fuel in the reservoir 3.

As shown in fig. 1, the injection valve body 11 is provided with a columnar water injection passage 72, annular water injection passages 73 and 75, and a symmetrical water injection passage 74, and the valve body support portion 27 of the water injection check valve 20 is provided with a symmetrical water injection passage 76. The columnar water injection passage 72 is a water passage formed in a columnar shape, and an opening is provided in the rear end portion of the injection valve main body 11. The annular water injection passage 73 is formed by a gap between the inner wall surface of the valve body fastening metal fitting 30 and the outer wall surface of the injection valve body 11, and is formed in an annular shape surrounding the water injection check valve 20 (e.g., the valve body support portion 27) as shown in fig. 1 and 2, for example. The symmetrical water injection passage 74 is a water passage formed to be axisymmetrical with respect to the operation direction center axis of the water injection check valve 20. In the first embodiment, as shown in fig. 1 and 2, the symmetrical water injection passages 74 are formed by a plurality of (for example, four) water passages formed (provided with holes) at equal angular intervals in the injection valve main body 11 around the center axis in the operation direction of the water injection check valve 20. The annular water injection passage 75 is formed of, for example, a groove provided on the inner peripheral surface of the injection valve body 11 (the inner wall surface of the check valve housing portion 12). As shown in fig. 1 and 2, the annular water injection passage 75 is located between the outlet end of the symmetrical water injection passage 74 and the inlet end of the symmetrical water injection passage 76, and is formed in an annular shape surrounding the water injection check valve 20 (the valve body support portion 27, etc.). The symmetrical water injection passage 76 is formed to be axisymmetrical with respect to the center axis in the operation direction of the water injection check valve 20, and is a water passage having a discharge port facing the water injection check valve 20 (specifically, the pressure receiving portion 23 of the valve body 21). In the first embodiment, as shown in fig. 1 and 2, the symmetrical water injection passages 76 are formed by a plurality of (for example, four) water passages formed (provided with holes) at equal angular intervals in the valve body support portion 27 around the center axis in the operation direction of the water injection check valve 20.

The central axis of the water injection check valve 20 in the direction of operation is the central axis of the valve body 21 in the direction of sliding. In the first embodiment, the operation direction center axis of the water injection check valve 20 coincides with the longitudinal direction center axis of the fuel injection valve 100 or is parallel to the longitudinal direction center axis.

The columnar water injection passage 72, the annular water injection passages 73 and 75, and the symmetrical water injection passages 74 and 76 are water passages that are part of the first water injection passage of the fuel injection valve 100. As shown in fig. 1 and 2, the cylindrical water injection passage 72 leads to an annular water injection passage 73, the annular water injection passage 73 leads to a symmetrical water injection passage 74, the symmetrical water injection passage 74 leads to an annular water injection passage 75, and the annular water injection passage 75 leads to a symmetrical water injection passage 76. When the valve body 21 is separated from the valve seat 24, the symmetric water injection passage 76 communicates with the first water injection position P1 in the fuel passage of the fuel injection valve 100. As shown in fig. 1, an O-ring 91 for preventing water leakage from the annular water injection passage 73 and the like is provided on the outer wall surface of the injection valve body 11 at a position between the annular water injection passage 73 and the distal end portion of the valve body fastening metal fitting 30.

On the other hand, the injection valve main body 40 constitutes a rear end portion of the fuel injection valve 100. As shown in fig. 1, the injection valve main body 40 is provided with a receiving portion 41 having a hole shape that is long in the axial direction F1. In the housing portion 41, a needle spring 50, a spring support portion 51, and a water injection check valve 60 corresponding to a second water injection path of the fuel injection valve 100 are housed. In the first embodiment, the second water injection passage is a passage for injecting water into the fuel oil passage of the fuel injection valve 100 at a position upstream of the first water injection passage in the direction of pressure-feeding the fuel (for example, the second water injection position P2 shown in fig. 1).

The needle spring 50 urges the needle 6 toward the nozzle hole 4 to close the tip oil passage 5. As shown in fig. 1, the needle valve spring 50 is formed of, for example, a coil spring, and is accommodated in the accommodating portion 41 in a state of being attached to the spring support portion 51. The spring support portion 51 is accommodated in the accommodating portion 41 in a state of supporting the needle spring 50, and is slidably attached to an insertion hole 29 formed in a rear end portion of the valve body support portion 27 of the water injection check valve 20. The spring support portion 51 supports one end portion of the needle spring 50, and presses the other end portion of the needle spring 50 toward the rear end portion of the valve body support portion 27, thereby compressing the needle spring 50 to generate an urging force. Further, a spring support portion internal oil passage 52 that is a part of the fuel oil passage of the fuel injection valve 100 is provided in the spring support portion 51.

Water injection check valve 60 is a check valve (second water injection check valve) that openably closes the second water injection passage of fuel injection valve 100. As shown in fig. 1, the water filling check valve 60 is composed of a valve body 61, a valve seat 64, a check valve spring 66, and a valve body support portion 67, and is disposed on the opposite side of the nozzle hole 4 with respect to the needle spring 50. In the first embodiment, the water injection check valve 60 corresponding to the second water injection passage and the water injection check valve 20 corresponding to the first water injection passage are disposed on opposite sides in the axial direction F1 with the needle spring 50 interposed therebetween. At this time, the two water injection check valves 20 and 60 are preferably arranged coaxially in the axial direction F1.

As shown in fig. 1, the valve body 61 has a pressure receiving portion 63 that receives the pressure of the water from the second water injection passage, and is slidably accommodated in a valve body supporting portion 67. As shown in fig. 1 and 3, the pressure receiving portion 63 is formed annularly around the outer periphery of the valve body 61 in the vicinity of the tip end portion thereof. Further, an in-valve-body oil passage 62, which is a part of the fuel oil passage of the fuel injection valve 100, is provided in the valve body 61. As shown in fig. 1, the valve seat 64 is fixed to the distal end portion of the valve body support portion 67 by fastening or the like. An in-seat oil passage 65 that is a part of the fuel oil passage of the fuel injection valve 100 is provided in the valve seat 64. As shown in fig. 1, the check valve spring 66 is disposed between the rear end portion of the valve body 61 and the valve body support portion 67. The check valve spring 66 applies a biasing force applied to the valve seat 64 side to the spool 61. The water injection check valve 60 presses the valve body 61 toward the valve seat 64 by the biasing force of the check valve spring 66, thereby openably blocking communication between the fuel oil passage of the fuel injection valve 100 and the second water injection passage. The valve body support portion 67 is configured to be threadably inserted into the housing portion 41 of the injection valve main body 40. A support portion internal oil passage 68 that is a part of the fuel oil passage of the fuel injection valve 100 is provided in the valve body support portion 67. As shown in fig. 1, a fuel supply pipe 90 that communicates with the support-inside oil passage 68 is connected to the rear end of the valve body support portion 67. The fuel supply pipe 90 is a pipe for introducing fuel pressure-fed by a fuel injection pump (not shown) into a fuel oil passage of the fuel injection valve 100.

In the first embodiment, the water injection check valve 60 has both the function as the check valve described above and the function as an adjustment spring for adjusting the biasing force of the needle spring 50 (i.e., the valve opening pressure of the needle 6). Specifically, as shown in fig. 1, the water filling check valve 60 is attached by screwing the valve body support portion 67 into the housing portion 41 of the injection valve main body 40. The water injection check valve 60 screwed into the housing portion 41 is in a state in which the tip end portion of the valve seat 64 abuts against the rear end portion of the spring support portion 51. The water injection check valve 60 adjusts the biasing force of the needle spring 50 by adjusting the screw feed amount into the housing portion 41. Specifically, the water injection check valve 60 increases the amount of screw feed into the housing portion 41 to increase the amount of press-fitting into the spring support portion 51 on the nozzle hole 4 side, thereby increasing the amount of compression of the needle spring 50 and adjusting the biasing force to be stronger. On the other hand, the water injection check valve 60 reduces the screw feed amount into the housing portion 41 to reduce the pushing amount into the spring support portion 51 on the nozzle hole 4 side, thereby reducing the compression amount of the needle spring 50 and further adjusting the biasing force to be weak.

As shown in fig. 1 and 3, the injection valve body 40 is provided with columnar water injection passages 71 and 81, and the valve support portion 67 of the water injection check valve 60 is provided with an annular water injection passage 82 and a symmetrical water injection passage 84. The columnar water injection passages 71 and 81 are water passages having a columnar shape, and are provided with respective openings at different positions from each other in the injection valve main body 40. The annular water injection passage 82 is constituted by, for example, a groove provided on the outer peripheral surface of the valve body support portion 67. As shown in fig. 3, the annular water injection passage 82 is located between the outlet end of the columnar water injection passage 81 and the inlet end of the symmetrical water injection passage 84, and is formed in an annular shape surrounding the water injection check valve 60 (the valve body 61, etc.). The symmetrical water injection passage 84 is formed in axial symmetry with respect to the center axis in the operation direction of the water injection check valve 60, and has a discharge port facing the water injection check valve 60 (specifically, the pressure receiving portion 63 of the valve body 61). In the first embodiment, as shown in fig. 1 and 3, the symmetrical water injection passages 84 are formed by a plurality of (for example, four) water passages formed (provided with holes) at equal angular intervals in the valve body support portion 67 around the center axis in the operation direction of the water injection check valve 60.

The center axis of the water injection check valve 60 in the operation direction is the center axis of the valve body 61 in the sliding direction. In the first embodiment, the operation direction center axis of the water injection check valve 60 coincides with or is parallel to the longitudinal direction center axis of the fuel injection valve 100.

The columnar water injection passage 71 is a water passage that is a part of the first water injection passage of the fuel injection valve 100. As shown in fig. 1, the columnar water injection passage 71 leads to the columnar water injection passage 72 in the injection valve main body 11. On the other hand, the columnar water injection passage 81, the annular water injection passage 82, and the symmetrical water injection passage 84 are water passages that are part of the second water injection passage of the fuel injection valve 100. As shown in fig. 1 and 3, the columnar water injection passage 81 leads to an annular water injection passage 82, and the annular water injection passage 82 leads to a symmetrical water injection passage 84. When the valve body 61 is separated from the valve seat 64, the symmetric water injection passage 84 communicates with the second water injection position P2 in the fuel passage of the fuel injection valve 100. As shown in fig. 1, O- rings 92 and 93 for preventing water leakage from the annular water injection passage 82 and the like are provided on the outer peripheral surface of the valve body support portion 67 at positions sandwiching the annular water injection passage 82.

Next, a fuel passage of the fuel injection valve 100 according to the first embodiment will be described. The fuel oil passage of the fuel injection valve 100 is a passage (oil passage) through which fuel pressure-fed from a fuel injection pump flows. In the first embodiment, the fuel oil path of the fuel injection valve 100 is constituted by the needle valve internal oil path 7, the spool internal oil paths 22 and 62, the seat internal oil paths 25 and 65, the support portion internal oil paths 28 and 68, and the spring support portion internal oil path 52 shown in fig. 1.

Specifically, as shown in fig. 1, in the fuel oil passages of the fuel injection valve 100, the needle valve internal oil passage 7 communicates with the valve seat internal oil passage 25, the valve seat internal oil passage 25 communicates with the spool internal oil passage 22, and the spool internal oil passage 22 communicates with the support portion internal oil passage 28. The support portion internal oil passage 28 communicates with the spring support portion internal oil passage 52, and the spring support portion internal oil passage 52 communicates with the valve seat internal oil passage 65. The valve seat internal oil passage 65 communicates with the spool internal oil passage 62, and the spool internal oil passage 62 communicates with the support portion internal oil passage 68. The fuel oil passage of the fuel injection valve 100 constituted by these oil passages is arranged so as to pass through the longitudinal center axis of the fuel injection valve 100 (see the alternate long and short dash line in fig. 1), as shown in fig. 1, for example. The tip end side (injection hole 4 side) of the fuel oil passage of the fuel injection valve 100 is led from the needle internal oil passage 7 to the reservoir 3 through the communication hole 8 of the needle 6. The rear end side (fuel injection pump side) of the fuel oil passage of the fuel injection valve 100 leads to the fuel supply pipe 90 via the support portion internal oil passage 68.

Next, the first water injection passage and the second water injection passage of the fuel injection valve 100 according to the first embodiment will be described. In the first embodiment, the first water injection passage is a passage (water passage) for injecting water pressure-fed from the water injection pump to the first water injection position P1 of the fuel oil passage of the fuel injection valve 100 via the water injection check valve 20. As shown in fig. 1 and 2, the first water injection passage is configured such that a columnar water injection passage 71, a columnar water injection passage 72, an annular water injection passage 73, a symmetrical water injection passage 74, an annular water injection passage 75, and a symmetrical water injection passage 76 are communicated in this order. The first water injection passage leads from the columnar water injection passage 71 to the water injection pump via a water supply pipe (not shown). The annular water injection passage 73 is formed in an annular shape surrounding the water injection check valve 20, and has a wider water flow range than the columnar water injection passages 71 and 72. Therefore, even if the water passage width of the annular water injection passage 73 in the radial direction F2 is smaller than that of the columnar water injection passages 71, 72, the water passage volume per unit length in the axial direction F1 can be maintained to be equal to that of the columnar water injection passages 71, 72.

In the first embodiment, the second water injection passage is a passage (water passage) for injecting water pressure-fed from the water injection pump to the second water injection position P2 of the fuel oil passage of the fuel injection valve 100 via the water injection check valve 60. As shown in fig. 1 and 3, the second water injection passage is configured such that a columnar water injection passage 81, an annular water injection passage 82, and a symmetrical water injection passage 84 are communicated in this order. The second water injection passage leads from the columnar water injection passage 81 to the water injection pump via a water supply pipe (not shown). The water injection pump for pressure-feeding water to the second water injection passage may be the same water injection pump as the water injection pump for pressure-feeding water to the first water injection passage, or may be a different water injection pump.

Next, the operation of the fuel injection valve 100 according to the first embodiment will be described. The fuel injection valve 100 injects fuel and water in layers from the injection hole 4 into the combustion chamber in the cylinder of the marine diesel engine in one-cycle injection.

During a period from the end of injection in the one cycle to the next injection (hereinafter referred to as a non-fuel injection period), fuel pressure-fed from the fuel injection pump remains in the flow path from the fuel passage of the fuel injection valve 100 to the head end passage 5 via the reservoir 3 and in the fuel supply pipe 90. At this stage, the pressure of the fuel remaining in the reservoir 3 is lower than the valve opening pressure of the needle valve 6. Therefore, the needle valve 6 closes the tip oil passage 5 so as to be openable and closable. The valve opening pressure of the needle valve 6 is a pressure required to open the needle valve 6, and is set by the urging force of the needle valve spring 50 transmitted to the needle valve 6 via the water injection check valve 20.

In the non-fuel injection period, water pumped from the water injection pump remains in each of the first and second water injection passages of the fuel injection valve 100. At this stage, the pressure of the water remaining in the first water injection passage is lower than the valve opening pressure of the water injection check valve 20. Therefore, the water injection check valve 20 is in a state of openably blocking the communication of the fuel oil passage of the fuel injection valve 100 with the first water injection passage. Similarly, since the pressure of the water remaining in the second water injection passage is lower than the valve opening pressure of the water injection check valve 60, the water injection check valve 60 is in a state of openably blocking the communication between the fuel oil passage of the fuel injection valve 100 and the second water injection passage. The valve opening pressure of the water injection check valve 20 is a pressure required to open the water injection check valve 20, and is set by the biasing force of the check valve spring 26 that presses the valve body 21 against the valve seat 24. The valve opening pressure of the water injection check valve 60 is a pressure required for opening the water injection check valve 60, and is set by the biasing force of a check valve spring 66 that presses the valve body 61 against the valve seat 64.

Here, in the non-fuel injection period, when high-pressure water exceeding the valve opening pressure of the water injection check valve 20 is pumped from the water injection pump into the first water injection passage of the fuel injection valve 100, the high-pressure water flows through the respective interiors of the columnar water injection passages 71, 72, the annular water injection passage 73, the symmetrical water injection passage 74, the annular water injection passage 75, and the symmetrical water injection passage 76 described in fig. 1 and 2 in this order. The high-pressure water flows through the discharge port of the symmetrical water injection passage 76 so as to press the valve body 21 from a direction axially symmetrical with respect to the center axis in the operation direction of the water injection check valve 20. That is, the valve body 21 receives the pressure (water pressure) of the high-pressure water in axisymmetric relation at the pressure receiving portion 23. Since the water pressure is higher than the valve opening pressure of the water filling check valve 20, the valve body 21 slides against the biasing force of the check valve spring 26 by the water pressure, and is separated from the valve seat 24. Thus, the water injection check valve 20 opens the communication between the fuel oil passage of the fuel communication valve 100 and the first water injection.

At this stage, water in the first water injection passage is injected into the fuel oil passage of the fuel injection valve 100 from the position where the water injection check valve 20 is disposed. Specifically, water in the first water injection passage is injected from a direction axisymmetrical with respect to a fuel flow direction central axis of the fuel oil passage of the fuel injection valve 100 (for example, a longitudinal direction central axis of the fuel injection valve 100) to a first water injection position P1 in the fuel oil passage. The injected water is diffused in the fuel passage in an axisymmetrical manner (uniformly in the radial direction F2), and pushes back the residual fuel in the fuel passage to the rear end side (fuel injection pump side) in the axial direction F1. As a result, a first water-pouring layer, which is a first water-pouring layer, is formed in the fuel oil passage. Further, a first fuel layer composed of the fuel remaining in the fuel oil passage on the injection hole 4 side with respect to the first water injection position P1 is formed on the downstream side (injection hole 4 side) of the first water injection layer.

On the other hand, during the non-fuel injection period, when high-pressure water exceeding the valve opening pressure of the water injection check valve 60 is pumped from the water injection pump into the second water injection passage of the fuel injection valve 100, the high-pressure water flows through the respective interior portions of the columnar water injection passage 81, the annular water injection passage 82, and the symmetrical water injection passage 84 shown in fig. 1 and 3 in this order. The high-pressure water flows through the discharge port of the symmetrical water injection passage 84 so as to press the valve body 61 from a direction axially symmetrical with respect to the center axis in the operation direction of the water injection check valve 60. That is, the valve body 61 receives the water pressure of the high-pressure water in the pressure receiving portion 63 axisymmetrically. Since the water pressure is higher than the valve opening pressure of the water filling check valve 60, the valve body 61 slides against the biasing force of the check valve spring 66 by the water pressure, and is separated from the valve seat 64. Thus, the water injection check valve 60 opens the communication between the fuel oil passage of the fuel injection valve 100 and the second water injection passage.

At this stage, the water in the second water injection passage is injected into the fuel oil passage of the fuel injection valve 100 from the position where the water injection check valve 60 is disposed. Specifically, the water in the second water injection passage is injected from a direction axially symmetrical with respect to the center axis in the fuel flow direction of the fuel passage of the fuel injection valve 100 to the second water injection position P2 in the fuel passage. The injected water is diffused in the fuel passage in an axisymmetrical manner (uniformly in the radial direction F2), and pushes back the residual fuel in the fuel passage to the rear end side (fuel injection pump side) in the axial direction F1. As a result, a second water injection layer, which is a water injection layer of the second layer, is formed in the fuel oil passage. Further, a second fuel layer made of fuel remaining in the fuel oil passage is formed between the second water injection layer and the first water injection layer. Further, a third fuel layer composed of fuel remaining in the fuel oil passage on the fuel injection pump side from the second water injection position P2 is formed on the upstream side (fuel injection pump side) of the second water injection layer.

After the non-fuel injection period, the fuel is pressure-fed from the fuel injection pump into the fuel oil passage of the fuel injection valve 100, and the fuel and water are injected for one cycle into the combustion chamber in the cylinder of the marine diesel engine.

Specifically, during the period in which the injection is performed (hereinafter, referred to as a fuel injection period), the high-pressure fuel exceeding the valve opening pressure of the needle valve 6 is pressure-fed from the fuel injection pump into the fuel flow path of the fuel injection valve 100 via the fuel supply pipe 90. In this case, the pressure of the fuel pressure-fed from the fuel injection pump is transmitted from the communication hole 8 of the needle valve 6 to the fuel in the reservoir 3 by the fluid (residual fuel and injected water) present in the fuel flow path of the fuel injection valve 100. As a result, the pressure of the fuel in the reservoir 3 is increased to a higher pressure than the valve opening pressure of the needle valve 6. The needle valve 6 receives the pressure of the fuel in the reservoir 3 at its distal end portion, and slides against the biasing force of the needle valve spring 50 by the pressure of the fuel to separate from the opening portion (valve seat portion) of the distal end oil passage 5. At this time, the water injection check valve 20 slides together with the needle 6 in a direction against the urging force of the needle spring 50 (the rear end side in the axial direction F1). In this way, the needle valve 6 opens the communication between the fuel passage of the fuel injection valve 100 and the nozzle hole 4.

At this stage, the fuel injection valve 100 injects a circulation amount of fuel and water into the combustion chamber in the cylinder of the marine diesel engine. For example, the fuel injection valve 100 injects the first fuel layer, the first water injection layer, the second fuel layer, the second water injection layer, and the third fuel layer in the fuel oil passage in layers from the injection hole 4 to the combustion chamber in the cylinder in this order. Subsequently, the pressure of the fuel in the reservoir 3 is reduced to a pressure equal to or lower than the valve opening pressure of the needle valve 6. In this case, the needle 6 slides toward the nozzle hole 4 by the biasing force of the needle spring 50, and comes into contact with the seat portion of the tip end oil passage 5 again, thereby closing the tip end oil passage 5 so as to be openable and closable. In this way, the needle valve 6 can openably block the fuel oil passage of the fuel injection valve 100 from communicating with the nozzle holes 4.

As described above, in the fuel injection valve 100 according to the first embodiment of the present invention, the water injection check valve 20 in the first water injection passage is disposed on the injection hole 4 side and the water injection check valve 60 in the second water injection passage is disposed on the opposite side to the injection hole 4 with respect to the needle spring 50 that biases the needle 6 toward the injection hole 4 side, so that water in the first water injection passage is injected from the water injection check valve 20 to the first water injection position P1 in the fuel oil passage and water in the second water injection passage is injected from the water injection check valve 60 to the second water injection position P2 in the fuel oil passage.

Therefore, the water injection check valve 20 of the first water injection passage can be disposed near the needle 6, and the water injection check valve 20 of the first water injection passage and the water injection check valve 60 of the second water injection passage can be disposed apart from each other so that the amount of fuel between the water injection layers between the first water injection position P1 and the second water injection position P2 in the fuel oil passage is in an appropriate proportion (for example, about 10 to 20%) to the fuel injection amount per cycle, and the region between the two water injection check valves 20 and 60 can be effectively used as the region where the needle spring 50 is disposed. As a result, an appropriate distance between the water injection check valves 20 and 60 incorporated in the fuel injection valve 100 can be ensured, and an increase in size of the fuel injection valve 100 (particularly, an increase in length of the longitudinal structure) can be suppressed. By injecting fuel and water into the combustion chamber in the cylinder of the marine diesel engine using the fuel injection valve 100, water can be injected into the combustion chamber at the initial stage of fuel injection, and as a result, the amount of NOx that is easily generated in the combustion chamber at the initial stage of fuel combustion can be effectively reduced.

In the fuel injection valve 100 according to the first embodiment of the present invention, the water injection check valve 20 in the first water injection passage and the water injection check valve 60 in the second water injection passage are coaxially arranged in the longitudinal direction of the fuel injection valve 100 along the central axis. Therefore, the width of the area occupied by the arrangement of the two water injection check valves 20, 60 (the length in the radial direction F2 of the fuel injection valve 100) can be reduced. As a result, an increase in size (an increase in width) of the fuel injection valve 100 in the radial direction F2 can be suppressed.

In the fuel injection valve 100 according to the first embodiment of the present invention, the first water injection passage is formed to have the annular water injection passage 73, and the annular water injection passage 73 is formed in an annular shape surrounding the water injection check valve 20. Here, since the annular water injection passage 73 can expand the water flow range into an annular shape, even if the water passage width in the radial direction F2 is smaller than that of the columnar water passage, the water passage volume per unit length in the axial direction F1 can be made equal to that of the columnar water passage. Therefore, the water passage width in the region of the annular water passage 73 in the first water passage can be reduced without hindering the flow of water in the first water passage, and as a result, the miniaturization of the fuel injection valve 100 in the radial direction F2 can be promoted.

In the fuel injection valve 100 according to the first embodiment of the present invention, a fuel passage through which fuel pressure-fed from a fuel injection pump flows is disposed so as to pass through a longitudinal center axis of the fuel injection valve 100. Therefore, a plurality of components (for example, the needle valve 6, the water injection check valves 20 and 60, the spring support portion 51 of the needle valve spring 50, and the like) constituting the fuel oil passage can be arranged together on the longitudinal center axis of the fuel injection valve 100. As a result, the width of the region occupied by the arrangement of these plural components can be reduced, and therefore, the miniaturization of the fuel injection valve 100 in the radial direction F2 can be promoted.

(second embodiment)

Next, a second embodiment of the present invention will be explained. First, the structure of the fuel injection valve according to the second embodiment of the present invention will be described. Fig. 4 is a schematic cross-sectional view showing a configuration example of a fuel injection valve according to a second embodiment of the present invention. Fig. 5 is a schematic cross-sectional view showing a configuration example of a fuel injection valve according to a second embodiment of the present invention, as viewed from another point of view. Fig. 5 is a schematic sectional view of the fuel injection valve shown in fig. 4 as viewed from direction D. Fig. 6 is a schematic cross-sectional view of the fuel injection valve shown in fig. 4 taken along line C-C. The definitions of the axial direction F1 and the radial direction F2 are the same as those of the fuel injection valve 100 according to the first embodiment described above, which is replaced with the fuel injection valve 200 according to the second embodiment.

The fuel injection valve 200 according to the second embodiment is attached to a cylinder of a marine diesel engine, and injects (for example, injects in layers) fuel pressure-fed from a fuel injection pump and water pressure-fed from a water injection pump sequentially into a combustion chamber in the cylinder. As shown in fig. 4 and 5, the fuel injection valve 200 includes a nozzle 101 located at the tip end, an injection valve main body 111 located at the rear end side of the nozzle 101, and an intermediate metal fitting 112 located between the nozzle 101 and the injection valve main body 111. The nozzle 101, the injection valve body 111, and the intermediate metal fitting 112 are fastened from the outer periphery by the nut-shaped nozzle fastening metal fitting 110 in a state where the intermediate metal fitting 112 is sandwiched between the nozzle 101 and the injection valve body 111, and are thereby fixed in a state of being coupled in the axial direction F1.

Nozzle 101 constitutes the tip portion of fuel injection valve 200. As shown in fig. 4 and 5, a needle valve housing 102 having a hole shape long in the axial direction F1 is provided in the nozzle 101. A needle valve 106 is slidably accommodated in the needle valve accommodating portion 102, and the needle valve 106 openably blocks communication between the fuel passage of the fuel injection valve 200 and the injection holes 104. A tapered portion 106a that widens from the tip end side toward the rear end side in the axial direction F1 is provided at a middle portion of the needle valve 6. Further, a reservoir 103 is provided in the middle of the needle valve housing 102. When the needle valve 106 is housed in the needle valve housing 102, the tapered portion 106a is positioned in the reservoir 103.

As shown in fig. 4 and 5, a nozzle hole 104 and a tip oil passage 105 are provided on the tip side of the nozzle 101. One end of the tip end oil passage 105 leads to a fuel oil passage of the fuel injection valve 200 via the needle valve housing portion 102. The other end of the tip oil passage 105 leads to the nozzle hole 104. As shown in fig. 4, a columnar fuel passage 174 as a part of a fuel passage of the fuel injection valve 200 is provided in the nozzle 101. The columnar fuel oil passage 174 is a columnar oil passage, and an opening is provided in a region that is distant from the center in the operation direction of the needle valve 106 in the width direction of the fuel injection valve 200 (the left side in the radial direction F2 shown in fig. 4). The columnar fuel passage 174 extends obliquely with respect to the axial direction F1, and leads from the reservoir 103 to the tip end oil passage 105 via the needle valve housing portion 102. The operation direction center axis of the needle valve 106 is the center axis of the needle valve 106 in the sliding direction.

The intermediate metal 112 constitutes an intermediate portion between the nozzle 101 and the injection valve main body 111. As shown in fig. 4 and 5, an insertion hole 113 that is long in the axial direction F1 is provided in the intermediate metal fitting 112. A push rod 155 for pushing the needle valve 106 toward the nozzle hole 104 is slidably inserted into the insertion hole 113. As shown in fig. 4 to 6, the intermediate metal fitting 112 is provided with a water injection check valve 120 corresponding to the first water injection passage of the fuel injection valve 200, a columnar fuel oil passage 173 that is a part of the fuel oil passage of the fuel injection valve 200, and a merging passage 176. In the second embodiment, the first water injection passage is a passage for injecting water to a predetermined position (first water injection position P1 shown in fig. 4) of the fuel oil passage of fuel injection valve 200.

Water injection check valve 120 is a check valve (first water injection check valve) that openably closes a first water injection passage of fuel injection valve 200. In the second embodiment, although not shown, the water injection check valve 120 is configured by a valve body, a valve seat, a check valve spring, and the like, and openably blocks communication between the columnar water injection passage 182, which is a part of the first water injection passage, and the merging passage 176. As shown in fig. 5, the water injection check valve 120 is disposed on the injection hole 104 side of a needle spring 150 described later. Further, the water injection check valve 120 is located in a region that is distant from the center axis in the operation direction of the needle valve 106 in the width direction of the fuel injection valve 200.

The columnar fuel oil passage 173 is a columnar oil passage, and an opening is provided in a region that is distant from the center in the operation direction of the needle valve 106 in the width direction of the fuel injection valve 200 (the left side in the radial direction F2 shown in fig. 4). Cylindrical fuel oil passage 173 extends in axial direction F1, and communicates cylindrical fuel oil passage 174 in nozzle 101 with cylindrical fuel oil passage 172 in injection valve main body 111. The merging passage 176 is a passage for merging the water flowing from the first water injection passage through the water injection check valve 120 and the fuel in the fuel oil passage of the fuel injection valve 200. For example, the merging passage 176 is formed by a groove or the like provided on an end surface of the intermediate metal member 112. As shown in fig. 4 to 6, one end of the confluence passage 176 leads to the water injection check valve 120, and the other end leads to the columnar fuel oil passage 173.

The injection valve main body 111 constitutes a portion from the middle portion to the rear end portion of the fuel injection valve 200. As shown in fig. 4 and 5, the injection valve main body 111 is provided with a hole-shaped housing portion 141 that is long in the axial direction F1. The needle spring 150, the spring support portion 151, the push rod 155, and the adjustment screw 156 are accommodated in the accommodation portion 141.

The needle spring 150 urges the needle 106 toward the nozzle hole 104 to close the tip oil passage 105. As shown in fig. 4 and 5, the needle valve spring 150 is formed of, for example, a coil spring, and is accommodated in the accommodating portion 141 in a state of being sandwiched between the spring support portion 151 and the adjustment screw 156. The spring support portion 151 is a support member that supports the needle spring 150, and is housed in the housing portion 141 in a state of being fixed to the rear end portion of the push rod 155. The spring support portion 151 supports one end portion of the needle spring 150, and presses the other end portion of the needle spring 150 toward the tip end portion of the adjustment screw 156, whereby the needle spring 150 is compressed, generating a biasing force. The push rod 155 is slidably disposed from the receiving portion 141 to the insertion hole 113. The tip end portion of the push rod 155 contacts the rear end portion of the needle valve 106. The rear end of the push rod 155 contacts the spring support 151. The push rod 155 presses the needle 106 toward the tip oil passage 105 by the biasing force of the needle spring 150 transmitted from the spring support portion 151. The push rod 155 slides in a direction against the urging force of the needle spring 150 (in a direction to compress the needle spring 150) together with the needle 106 that slides in a direction away from the tip oil passage 105 by the pressure of the fuel in the reservoir 103.

The adjustment screw 156 is used to adjust the urging force of the needle spring 150 (i.e., the valve-opening pressure of the needle 106). As shown in fig. 4 and 5, the adjusting screw 156 is attached by being screwed into the receiving portion 141 of the injection valve main body 111. The adjustment screw 156 screwed into the housing 141 is in a state in which the tip end thereof abuts against the rear end of the needle spring 150. The adjustment screw 156 adjusts the biasing force of the needle spring 150 by adjusting the screw feed amount into the housing portion 141. Specifically, the adjustment screw 156 increases the compression amount of the needle spring 150 by increasing the screw feed amount into the housing portion 141, thereby adjusting the acting force to be increased. On the other hand, the adjustment screw 156 reduces the amount of screw feed into the housing portion 141 to reduce the amount of compression of the needle spring 150, thereby adjusting the biasing force to be weak.

As shown in fig. 4, a columnar fuel passage 172 is provided in the injection valve main body 111 as a part of the fuel passage of the fuel injection valve 200. The columnar fuel oil passage 172 is an oil passage having a columnar shape, and an opening is provided in a region distant from the center in the operation direction of the needle valve 106 toward the width direction of the fuel injection valve 200 (the left side in the radial direction F2 shown in fig. 4). The cylindrical fuel oil passage 172 extends obliquely with respect to the axial direction F1, and opens into the cylindrical fuel oil passage 173 in the intermediate metal member 112. In addition, the rear end portion of the columnar fuel oil passage 172 opens to the fuel receiving portion 171. The fuel receiver 171 receives fuel pressure-fed by a fuel injection pump. As shown in fig. 4, one end portion of the fuel receiving portion 171 is attached to the rear end portion of the injection valve main body 111. A fuel supply pipe 90 leading to the fuel injection pump is connected to the other end of the fuel receiver 171. The fuel receiving portion 171 communicates the fuel supply pipe 90 with the columnar fuel oil passage 172.

As shown in fig. 5, the injection valve main body 111 is provided with a water injection check valve 160 corresponding to the second water injection passage of the fuel injection valve 200, a stopper 167, water receiving portions 181, 185, columnar water injection passages 182, 186, and a merging passage 175. In the second embodiment, the second water injection passage is a water passage for injecting water to a position (for example, a second water injection position P2 shown in fig. 4) on the upstream side in the pressure-feed direction of the fuel with respect to the first water injection passage in the fuel oil passage of the fuel injection valve 200.

Water injection check valve 160 is a check valve (second water injection check valve) that closes a second water injection passage of fuel injection valve 200 so as to be openable and closable. In the second embodiment, although not shown, the water injection check valve 160 is configured by a valve body, a valve seat, a check valve spring, and the like, and openably blocks communication between the columnar water injection passage 186, which is a part of the second water injection passage, and the merging passage 175. As shown in fig. 5, the water injection check valve 160 is disposed on the side opposite to the injection holes 104 with reference to the needle spring 150. The water injection check valve 160 is located in a region that is distant from the center axis of the needle valve 106 in the operation direction toward the width direction of the fuel injection valve 200. The stopper 167 receives one end (lower end in fig. 5) of the water filling check valve 160, and limits the sliding range of the water filling check valve 160.

The columnar water injection passage 182 is a columnar water passage that is a part of the first water injection passage of the fuel injection valve 200, and an opening is provided in a region that is distant from the center axis in the direction of action of the needle valve 106 toward the width direction (in fig. 5, the right side) of the fuel injection valve 200. The cylindrical water injection passage 182 extends obliquely with respect to the axial direction F1, leading to the water injection check valve 120 in the middle metal piece 112. Further, a rear end portion of the columnar water injection passage 182 leads to the water receiving portion 181. As shown in fig. 5, the water receiving part 181 receives water pressure-fed by a water injection pump, and is provided in the rear end portion of the injection valve main body 111. The water receiving unit 181 communicates a water supply pipe (not shown) leading to the water injection pump with the columnar water injection passage 182.

The columnar water injection passage 186 is a columnar water passage that is a part of the second water injection passage of the fuel injection valve 200, and an opening is provided in a region that is distant from the center axis in the direction of action of the needle valve 106 toward the width direction (left side in fig. 5) of the fuel injection valve 200. The cylindrical water injection passage 186 extends in the axial direction F1, and communicates the water receiving portion 185 with the water injection check valve 160. As shown in fig. 5, the water receiving portion 185 receives water pressure-fed by the water injection pump, and is provided in the rear end portion of the injection valve main body 111. The water receiving portion 185 communicates a water supply pipe (not shown) leading to the water injection pump with the columnar water injection passage 186.

The merging passage 175 is a passage for merging the water flowing from the second water injection passage through the water injection check valve 160 with the fuel in the fuel oil passage of the fuel injection valve 200. For example, the merging passage 175 is formed of a passage or the like provided in a columnar shape in the injection valve main body 111. As shown in fig. 4 and 5, one end of the merging passage 175 leads to the water injection check valve 160, and the other end leads to the columnar fuel oil passage 172.

Next, a fuel passage of the fuel injection valve 200 according to the second embodiment will be described. The fuel oil passage of the fuel injection valve 200 is a passage (oil passage) through which fuel pressure-fed from the fuel injection pump flows. The fuel passages of fuel injection valve 200 are formed by connecting columnar fuel passages 172, 173, and 174 shown in fig. 4. Such a fuel oil passage is disposed at a position distant from the longitudinal center axis of fuel injection valve 200 in radial direction F2 (left side in fig. 4).

As shown in fig. 4, the first water injection position P1 at which water is injected from the first water injection passage among the fuel oil passages of the fuel injection valve 200 is a position at which the columnar fuel oil passage 173 in the intermediate metal fitting 112 merges with the merging passage 176. The second water injection position P2 at which water is injected from the second water injection passage is a position at which the columnar fuel oil passage 172 and the merging passage 175 in the injection valve main body 111 merge together.

Next, a first water injection passage and a second water injection passage of fuel injection valve 200 according to the second embodiment will be described. In the second embodiment, the first water injection passage is a passage (water passage) for injecting water pressure-fed from the water injection pump to the first water injection position P1 of the fuel oil passage of the fuel injection valve 200 via the water injection check valve 120 and the like. As shown in fig. 5, the first water injection passage is configured by communicating the columnar water injection passage 182, the water injection check valve 120, and the merging passage 176 in this order.

In the second embodiment, the second water injection passage is a passage (water passage) for injecting water pressure-fed from the water injection pump to the second water injection position P2 of the fuel oil passage of the fuel injection valve 200 via the water injection check valve 160. As shown in fig. 5, the second water injection passage is configured such that the columnar water injection passage 186, the water injection check valve 160, and the merging passage 175 communicate in this order. The water injection pump for pressure-feeding water to the second water injection passage may be the same water injection pump as the water injection pump for pressure-feeding water to the first water injection passage, or may be a different water injection pump.

Next, the operation of the fuel injection valve 200 according to the second embodiment will be described. The fuel injection valve 200 injects fuel and water in layers from the injection hole 104 into the combustion chamber in the cylinder of the marine diesel engine in one injection cycle.

During the non-fuel injection period from the end of injection in this cycle to the next injection, fuel pressure-fed from the fuel injection pump remains in the flow path from the fuel passage of the fuel injection valve 200 to the tip end passage 105 through the needle valve housing portion 102, in the fuel receiving portion 171, and in the fuel supply pipe 90. At this stage, the pressure of the fuel remaining in the reservoir 103 is lower than the valve opening pressure of the needle valve 106. Therefore, the needle valve 106 closes the tip oil passage 105 so as to be openable and closable. The valve opening pressure of the needle valve 106 is set by the biasing force of the needle valve spring 150 transmitted to the needle valve 106 via the spring support 151 and the push rod 155.

In the non-fuel injection period, water pumped from the water injection pump remains in each of the first and second water injection passages of the fuel injection valve 200. At this stage, the pressure of the water remaining in the first water injection passage is lower than the valve opening pressure of the water injection check valve 120. Therefore, water injection check valve 120 is in a state of openably blocking the communication of the fuel oil passage of fuel injection valve 200 with the first water injection passage. Similarly, since the pressure of the water remaining in the second water injection passage is lower than the valve opening pressure of the water injection check valve 160, the water injection check valve 160 is in a state of openably blocking the communication between the fuel oil passage of the fuel injection valve 200 and the second water injection passage.

Here, during the non-fuel injection period, when high-pressure water exceeding the valve opening pressure of the water injection check valve 120 is pumped from the water injection pump into the first water injection passage of the fuel injection valve 200, the high-pressure water flows through the water receiving portion 181 and the columnar water injection passage 182 described in fig. 5 in this order. The high-pressure water flows into the water injection check valve 120 from the columnar water injection passage 182. Since the water pressure is higher than the valve opening pressure of the water injection check valve 120, the water injection check valve 120 is opened by the water pressure, and the fuel passage of the fuel injection valve 200 is opened to communicate with the first water injection passage. Specifically, the water injection check valve 120 communicates the columnar water injection passage 182 with the confluence passage 176, and communicates the columnar water injection passage 182 with the columnar fuel oil passage 173 via the confluence passage 176.

At this stage, water in the first water injection passage is injected into the fuel oil passage of fuel injection valve 200 from the position where water injection check valve 120 is disposed. Specifically, the water in the first water injection passage is injected from the water injection check valve 120 through the merging passage 176 to the first water injection position P1 in the fuel oil passage. The injected water pushes back the residual fuel in the fuel oil passage to the rear end side (fuel injection pump side) in the axial direction F1. As a result, a first water injection layer, which is a first water injection layer, is formed in the fuel oil passage. Further, a first fuel layer composed of the fuel remaining in the fuel oil passage on the injection hole 104 side with respect to the first water injection position P1 is formed on the downstream side (injection hole 104 side) of the first water injection layer.

On the other hand, during the non-fuel injection period, when high-pressure water exceeding the valve opening pressure of the water injection check valve 160 is pumped from the water injection pump into the second water injection passage of the fuel injection valve 200, the high-pressure water flows through the water receiving portion 185 and the columnar water injection passage 186 shown in fig. 5 in this order. The high-pressure water flows into the water injection check valve 160 from the columnar water injection passage 186. Since the water pressure is higher than the valve opening pressure of the water injection check valve 160, the water injection check valve 160 is opened by the water pressure, and the fuel passage of the fuel injection valve 200 and the second water injection passage are opened. Specifically, the water injection check valve 160 communicates the columnar water injection passage 186 with the merging passage 175, and communicates the columnar water injection passage 186 with the columnar fuel oil passage 172 via the merging passage 175.

At this stage, the water in the second water injection passage is injected into the fuel oil passage of fuel injection valve 200 from the position where water injection check valve 160 is disposed. Specifically, the water in the second water injection passage is injected from the water injection check valve 160 through the merging passage 175 to the second water injection position P2 in the fuel oil passage. The injected water pushes back the residual fuel in the fuel oil passage to the rear end side (fuel injection pump side) in the axial direction F1. As a result, a second water injection layer, which is a water injection layer of the second layer, is formed in the fuel oil passage. Further, a second fuel layer made of fuel remaining in the fuel oil passage is formed between the second water injection layer and the first water injection layer. Further, a third fuel layer composed of fuel remaining in the fuel oil passage on the fuel injection pump side from the second water injection position P2 is formed on the upstream side (fuel injection pump side) of the second water injection layer.

After the non-fuel injection period, the fuel is pressure-fed from the fuel injection pump into the fuel oil passage of the fuel injection valve 200, and the fuel and water are injected for one cycle into the combustion chamber in the cylinder of the marine diesel engine.

Specifically, during this fuel injection period, high-pressure fuel exceeding the valve opening pressure of the needle valve 106 is pressure-fed from the fuel injection pump into the fuel flow path of the fuel injection valve 200 via the fuel supply pipe 90. In this case, the pressure of the fuel pressure-fed from the fuel injection pump is transmitted to the fuel in the reservoir 103 through the fluid (residual fuel and injected water) present in the fuel flow path of the fuel injection valve 200. As a result, the pressure of the fuel in the reservoir 103 is increased to a higher pressure than the valve opening pressure of the needle valve 106. The needle valve 106 receives the pressure of the pressurized fuel in the reservoir 103 at the tapered portion 106a, and slides against the biasing force of the needle valve spring 150 by the pressure of the fuel, and separates from the opening portion (valve seat portion) of the tip oil passage 105. In this way, the needle valve 106 opens the fuel passage of the fuel injection valve 200 to the nozzle holes 104.

At this stage, the fuel injection valve 200 injects a circulation amount of fuel and water into the combustion chamber in the cylinder of the marine diesel engine. For example, the fuel injection valve 200 injects the first fuel layer, the first water injection layer, the second fuel layer, the second water injection layer, and the third fuel layer in the fuel oil passage in layers from the injection hole 104 into the combustion chamber in the cylinder in this order. Subsequently, the pressure of the fuel in the reservoir 103 is reduced to a pressure equal to or lower than the valve opening pressure of the needle valve 106. In this case, the needle 106 slides toward the nozzle hole 104 by the biasing force of the needle spring 150, and comes into contact with the seat portion of the tip oil passage 105 again, thereby closing the tip oil passage 105 so as to be openable and closable. In this way, the needle valve 106 may openly block the fuel oil path of the fuel injection valve 200 from communicating with the nozzle holes 104.

As described above, in the fuel injection valve 200 according to the second embodiment of the present invention, the water injection check valve 120 in the first water injection passage is disposed on the injection hole 104 side and the water injection check valve 160 in the second water injection passage is disposed on the opposite side to the injection hole 104 with respect to the needle spring 150 that biases the needle 106 toward the injection hole 104, so that water in the first water injection passage is injected from the water injection check valve 120 through the merging passage 175 to the first water injection position P1 in the fuel oil passage, and water in the second water injection passage is injected from the water injection check valve 160 through the merging passage 176 to the second water injection position P2 in the fuel oil passage.

Therefore, the water injection check valve 120 of the first water injection passage can be disposed near the needle 106, the water injection check valve 120 of the first water injection passage can be disposed apart from the water injection check valve 160 of the second water injection passage, the amount of fuel between the water injection layers between the first water injection position P1 and the second water injection position P2 in the fuel oil passage can be made to be appropriately proportional to the fuel injection amount per cycle (for example, about 10 to 20%), and the region between the two water injection check valves 120 and 160 can be effectively used as the region where the needle spring 150 is disposed. As a result, an appropriate distance between the water injection check valves 120 and 160 incorporated in the fuel injection valve 200 can be secured, and an increase in size of the fuel injection valve 200 (particularly, an increase in length of the longitudinal structure) can be suppressed. By injecting fuel and water into the combustion chamber in the cylinder of the marine diesel engine using the fuel injection valve 200, water can be injected into the combustion chamber from the initial stage of fuel injection, and as a result, the amount of NOx that is easily generated in the combustion chamber at the initial stage of combustion of the fuel can be effectively reduced.

In the fuel injection valve 200 according to the second embodiment of the present invention, a fuel passage through which fuel pumped from a fuel injection pump flows is disposed at a position radially distant from the longitudinal center axis of the fuel injection valve 200. Therefore, the fuel oil path can be provided avoiding the needle valve 106, the needle valve spring 150, the spring support portion 151, the push rod 155, the adjustment screw 156, and other components arranged near the longitudinal center axis of the fuel injection valve 200. Thus, it is not necessary to form the fuel oil passage by connecting passages in a plurality of components disposed in the vicinity of the longitudinal center axis of fuel injection valve 200, and therefore the number of components forming the fuel oil passage can be reduced, and the connecting portions between the passages of the fuel oil passage can be reduced.

In the first embodiment, the symmetrical water injection passages formed by four water passages formed at equal angular intervals around the central axis in the operation direction of the water injection check valve are exemplified as an example of the symmetrical water injection passages for discharging water to the valve body of the water injection check valve, but the present invention is not limited thereto. In the present invention, the symmetrical water injection passage may be composed of two or more (a plurality of) water passages formed at equal angular intervals around the central axis in the operation direction of the water injection check valve, or may be composed of a single annular water passage having an annular discharge port continuous around the central axis in the operation direction of the water injection check valve.

In the first embodiment described above, a configuration having an annular water injection passage is exemplified as an example of the first water injection passage and the second water injection passage, but the present invention is not limited to this. For example, the first and second water injection passages may be formed by directly connecting a symmetrical water injection passage, which is formed in the valve body of the water injection check valve and faces the discharge port, to a columnar water injection passage, which receives water pressure-fed from the water injection pump.

In the first embodiment described above, a valve element having a pressure receiving portion on the outer periphery thereof for receiving the pressure of water discharged from the discharge port of the symmetrical water injection passage is exemplified as an example of a valve element of the water injection check valve. For example, the valve body of the water injection check valve may receive the pressure of water at the outer peripheral portion or the distal end portion without providing a pressure receiving portion.

In the first embodiment described above, the configuration in which the valve body of the water injection check valve discharges water in the direction axially symmetrical with respect to the center axis in the operation direction of the water injection check valve is exemplified as an example of the first water injection passage and the second water injection passage, but the present invention is not limited to this. For example, the first and second water injection paths may discharge water in asymmetric directions (single direction or the like) with respect to the valve body of the water injection check valve.

In the first and second embodiments described above, the fuel injection valve provided with two water injection check valves is exemplified, but the present invention is not limited to this. For example, the number of water injection check valves provided in the fuel injection valve may be three or more. In this case, the three or more water injection check valves may be provided at the rear end portion of the injection valve main body of the fuel injection valve, or may be provided at a joint portion between a pipe from the fuel injection pump and a pipe from the water injection pump.

The present invention is not limited to the first and second embodiments described above, and configurations in which the above-described respective components are appropriately combined are also included in the present invention. In addition, other embodiments, examples, operation techniques, and the like, which are made by those skilled in the art based on the first and second embodiments described above, are all included in the scope of the present invention.

Industrial applicability of the invention

As described above, the fuel injection valve according to the present invention is applied to a fuel injection valve capable of ensuring an appropriate distance between the respective built-in water injection check valves and suppressing an increase in the size of the structure.

Description of the symbols

1 spray nozzle

2 needle valve housing part

3 storage part

4 spray orifice

5 top oil way

6 needle valve

7 needle valve internal oil path

8 communication hole

10 nozzle fastening metal piece

11 injection valve body

12 check valve housing

20 water filling check valve

21 valve core

22 valve core internal oil path

23 pressure-receiving portion

24 valve seat

25 oil circuit in valve seat

26 check valve spring

27 valve core support part

28 oil passage in support part

29 inserting into the hole

30 valve body fastening metal piece

40 injection valve body

41 housing part

50 needle type valve spring

51 spring support

52 spring support inner oil passage

60 water injection check valve

61 valve core

62 valve core internal oil path

63 pressure-bearing portion

64 valve seat

65 valve seat internal oil path

66 check valve spring

67 valve core support part

68 support internal oil path

71. 72, 81 column-shaped water injection path

73. 75, 82 annular water injection channel

74. 76, 84 symmetrical water injection path

90 fuel supply pipe

91. 92, 93O-ring

100. 200 fuel injection valve

101 spray nozzle

102 needle valve accommodating part

103 storage part

104 jet orifice

105 top oil circuit

106 needle valve

106a taper part

110 nozzle fastening metal piece

111 injection valve body

112 intermediate metal piece

113 inserting hole

120 water injection check valve

141 container part

150 needle valve spring

151 spring support

155 push rod

156 adjusting screw

160 water filling check valve

167 stop

171 fuel receiving part

172. 173, 174 columnar fuel oil path

175. 176 merging path

181. 185 water receiving part

182. 186 columnar water injection path

F1 axial direction

F2 radial direction

P1 first Water injection position

P2 second Water injection position

Claims (6)

1. A fuel injection valve for injecting fuel and water in a single-cycle injection in layers of four or more stages from an injection hole into a combustion chamber in a cylinder of a marine diesel engine, the fuel injection valve comprising:

a fuel passage through which the fuel pressure-fed from a fuel injection pump flows;

a tip oil passage having one end opening to the fuel oil passage and the other end opening to the nozzle hole;

a needle valve that closes the tip oil passage in an openable and closable manner;

a needle valve spring that applies a force to the needle valve toward the orifice side to close the top oil passage;

a first water injection passage for injecting water to a predetermined position of the fuel oil passage;

a second water injection passage for injecting water into the fuel oil passage at a position upstream of the first water injection passage in a direction in which the fuel is pumped;

a first water injection check valve disposed closer to the nozzle than the needle spring and closing the first water injection passage so as to be openable and closable; and

a second water injection check valve disposed on a side opposite to the injection hole with reference to the needle spring and closing the second water injection passage in an openable and closable manner,

the water in the first water injection passage is injected into the fuel oil passage from the position where the first water injection check valve is disposed, and the water in the second water injection passage is injected into the fuel oil passage from the position where the second water injection check valve is disposed.

2. The fuel injection valve according to claim 1,

the first water injection check valve and the second water injection check valve are coaxially arranged in a direction of a longitudinal center axis of the fuel injection valve.

3. The fuel injection valve according to claim 1,

the first water injection passage has an annular water injection passage formed in an annular shape surrounding the first water injection check valve.

4. The fuel injection valve according to claim 2,

the first water injection passage has an annular water injection passage formed in an annular shape surrounding the first water injection check valve.

5. The fuel injection valve according to any one of claims 1 to 4,

the fuel oil passage is disposed so as to pass through a longitudinal center axis of the fuel injection valve.

6. The fuel injection valve according to claim 1,

the fuel oil passage is disposed at a position axially spaced apart from a longitudinal center of the fuel injection valve in a radial direction.

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