JP3870873B2 - Fuel injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection device used for an internal combustion engine (hereinafter referred to as an engine).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a fuel injection device is known in which a nozzle hole is provided in a cover wall of a nozzle hole plate that covers an axial end surface of a cylindrical valve body, and fuel in the valve body is injected from the nozzle hole. In this fuel injection device, since the atomization of fuel spray is promoted as the length of the nozzle hole in the passage direction is shorter, it is required to make the cover wall of the nozzle hole plate thinner.
[0003]
However, if the cover wall of the injection hole plate is made thin, the injection hole plate may be fatigued by the fuel pressure. Particularly in a fuel injection device that directly injects fuel into a combustion chamber of a gasoline engine, the fuel pressure is 5 to 12 MPa, 16 to 40 times that of a fuel injection device that injects fuel into an intake pipe. Must be ensured.
[0004]
Therefore, a fuel injection device in which the nozzle hole plate is reinforced with a holding plate is disclosed in Japanese Patent Laid-Open No. 2000-73918. In the fuel injection device disclosed in this publication, a holding plate is provided on the counter valve body side of the cover wall of the nozzle hole plate, and the cover wall is supported by the holding plate. As a result, the compressive strength is ensured even with a thin wall.
[0005]
[Problems to be solved by the invention]
However, since the fuel injection device disclosed in Japanese Patent Application Laid-Open No. 2000-73918 adopts a structure in which a holding plate is combined with an injection hole plate, the manufacturing cost increases due to an increase in the number of parts. Furthermore, since the assembly work of a plurality of plates becomes complicated, industrial productivity is reduced.
Japanese Patent Application Laid-Open No. 2000-73918 discloses a fuel injection device in which an injection hole plate and a holding plate are both welded to a valve body. In this fuel injection device, since the plates are partially overlapped and welded at once, the energy consumption at the time of welding increases, the manufacturing cost increases, and the welding time increases, resulting in increased industrial productivity. There is a problem of falling.
[0006]
An object of the present invention is to provide a fuel injection device capable of realizing both atomization of fuel spray and simplification of the structure.
Another object of the present invention is to provide a fuel injection device capable of reducing manufacturing costs and improving industrial productivity.
[0007]
[Means for Solving the Problems]
According to the fuel injection device of the first aspect of the present invention, the nozzle hole plate has a cover wall that covers one axial end surface of the cylindrical valve body that forms the fuel passage, and is provided at the downstream end of the fuel passage. A communication hole is formed in the cover wall. Further, the cover wall of the nozzle hole plate has reinforcing ribs on the radially outer side of the nozzle hole. Therefore, the cover rib can be reinforced without increasing the number of parts by the reinforcing ribs, and the pressure resistance of the nozzle hole plate can be ensured. Therefore, the structure can be simplified while promoting atomization of the fuel spray by thinning the cover wall of the nozzle hole plate at the nozzle hole forming portion.
[0008]
According to the fuel injection device according to claim 1 in addition, cover wall of the injection hole plate is welded to a lower portion than the projection height of the reinforcing rib in the valve body. Therefore, since a relatively thin portion of the cover wall can be welded to the valve body, energy consumption during welding can be reduced and welding time can be shortened.
According to the fuel injection system according to this first aspect, it is possible to achieve the improvement of the reduction and industrial productivity of the manufacturing cost.
[0009]
According to the fuel injection device of the third aspect of the present invention, the nozzle hole plate is formed in a bottomed cylindrical shape having a peripheral wall and a bottom wall, and one axial end portion of the valve body is fitted to the inner peripheral side of the peripheral wall. The bottom wall forms a cover wall. Thereby, the fitting plate can be easily positioned with respect to the valve body by fitting the peripheral wall of the nozzle hole plate to the valve body.
[0010]
According to the fuel injection device of the first aspect of the present invention, the cover wall of the nozzle hole plate is welded to the valve body at a location that is radially outward from the radially innermost edge of the reinforcing rib. Thereby, the reinforcing effect of the covering wall by the reinforcing rib can be fully enjoyed.
According to the fuel injection device of the fourth aspect of the present invention, the welded portion of the cover wall of the nozzle hole plate to the valve body is set to be continuous in the circumferential direction on the radially outer side of the nozzle hole. Thereby, the welding intensity | strength of the nozzle hole plate with respect to a valve body can be raised. Further, it is possible to prevent the fuel from leaking outside through the cover wall of the nozzle hole plate and the valve body.
[0011]
According to the fuel injection device of the fifth aspect of the present invention, the reinforcing rib is formed so as to be continuous in the circumferential direction of the cover wall of the nozzle hole plate. Thereby, since the covering wall of a nozzle hole plate can be equally reinforced in the circumferential direction, durability of a nozzle hole plate improves.
[0012]
According to the fuel injection device of the first and sixth aspects of the present invention, the cover wall of the injection hole plate is welded to the valve body at the base portion of the reinforcing rib that protrudes toward the opposite valve body. Thereby, since a welding site | part is supported by a reinforcement rib, the welding strength of the nozzle hole plate with respect to a valve body is securable.
[0013]
According to the fuel injection device of the seventh aspect of the present invention, the portion of the cover wall of the injection hole plate that is radially outward from the injection hole forms a thicker part than the formation part of the injection hole. Further, the thick portion has a concave groove, and a reinforcing rib is formed at a portion which is radially inward of the concave groove. According to such a configuration, the reinforcing rib can be easily formed by, for example, drawing.
Furthermore, according to the fuel injection device of claim 7 , since the thick part of the nozzle hole plate is welded to the valve body using the bottom part of the concave groove that becomes thin, the energy consumption during welding is reduced and the welding is performed. Does not hinder time reduction.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of examples showing embodiments of the present invention will be described with reference to the drawings.
(First Example)
1 and 2 show a fuel injection device according to a first embodiment of the present invention. As shown in FIG. 3, the fuel injection device 10 of the first embodiment is attached to a cylinder head 4 surrounding the combustion chamber 2 of the gasoline engine, and can directly inject fuel into the combustion chamber 2.
[0015]
As shown in FIG. 2, the housing 11 is formed in a cylindrical shape, and includes a first magnetic part 12, a nonmagnetic part 13, and a second magnetic part 14 that are arranged coaxially. The nonmagnetic part 13 prevents a magnetic short circuit between the first magnetic part 12 and the second magnetic part 14. The fixed core 15 is formed of a magnetic material in a cylindrical shape, and is coaxially fixed to the inner peripheral side of the housing 11. The movable core 18 is formed of a magnetic material in a cylindrical shape and is coaxially accommodated on the inner peripheral side of the housing 11. The movable core 18 can reciprocate in the axial direction on the downstream side of the fixed core 15. The outflow hole 19 that penetrates the peripheral wall of the movable core 18 forms a fuel passage that communicates the inside and outside of the cylinder of the movable core 18.
[0016]
A spool 40 is mounted on the outer peripheral side of the housing 11, and a coil 41 is wound around the spool 40. A resin-molded connector 42 covers the outer peripheral side of the spool 40 and the coil 41. The terminal 43 is embedded in the connector 42 and is electrically connected to the coil 41. When the coil 41 is energized through the terminal 43, a magnetic attractive force acts between the fixed core 15 and the movable core 18.
[0017]
As shown in FIGS. 1 and 2, the nozzle holder 20 is formed in a cylindrical shape, and is coaxially fixed to the downstream end portion of the housing 11. The valve body 21 is formed in a cylindrical shape, and is fixed to the inner peripheral side of the downstream end portion of the nozzle holder 20 by welding. The valve body 21 forms a fuel passage 22 by its inner peripheral wall surface. Further, the inner peripheral wall surface of the valve body 21 forms a conical valve seat portion 24 whose diameter decreases as it approaches the opening 23 in the vicinity of the downstream opening 23.
[0018]
The nozzle hole plate 26 is formed in a so-called cup shape having a bottomed cylindrical shape by drawing a stainless steel plate or the like, and includes a peripheral wall 27 and a bottom wall 28.
As shown in FIGS. 1 and 4, the axially downstream end of the valve body 21 is coaxially fitted to the inner peripheral side of the peripheral wall 27, and the end surface 21a of the downstream end of the valve body 21 is the bottom. The inner wall 28a of the wall 28 is in contact with and covered with the inner wall 28a. That is, the bottom wall 28 forms the covering wall described in the claims. Further, the injection hole plate 26 is positioned in the radial direction with respect to the valve body 21 by the fitting of the peripheral wall 27 and the valve body 21. The nozzle holder 20 surrounds the outer peripheral side of the peripheral wall 27 with a slight clearance.
[0019]
The disc-shaped bottom wall 28 has a plurality of injection holes 29 formed at the center thereof. In the present embodiment, the plurality of nozzle holes 29 are arranged on the same circle around the central axis O of the bottom wall 28 and at equal intervals. The passage direction of each nozzle hole 29 is inclined at a predetermined angle with respect to the central axis O of the bottom wall 28. In addition, you may make it form an appropriate number of nozzle holes 29 further inside radial direction rather than the some nozzle holes 29 arrange | positioned on the same circle like a present Example. In addition, a good spray shape can be easily obtained by providing a plurality of nozzle holes 29, but only one nozzle hole 29 may be provided.
[0020]
The bottom wall 28 is further provided with a reinforcing rib 30 that protrudes toward the counter valve body. The reinforcing rib 30 is formed in an annular cross section continuous in the circumferential direction of the bottom wall 28 on the radially outer side of the outermost peripheral nozzle hole 29. In the present embodiment, all the nozzle holes 29 correspond to the outermost nozzle holes 29. However, when the nozzle holes 29 are provided radially inward of the plurality of nozzle holes 29 on the same circle, The nozzle holes 29 excluding the holes 29 correspond to the outermost peripheral nozzle holes 29, and when only one nozzle hole 29 is provided, the one nozzle hole 29 corresponds to the outermost peripheral nozzle hole 29. The central axis of the reinforcing rib 30 coincides with the central axis O of the bottom wall 28, and the inner diameter of the reinforcing rib 30 is set larger than the inner diameter of the opening 23 of the valve body 21. As a result, the opening 23 is covered by the portion 31 that is radially inward of the reinforcing rib 30 in the bottom wall 28, that is, by the thin portion 31 that forms the injection hole 29 and does not form the reinforcing rib 30 in the bottom wall 28. . Hereinafter, the portion 31 is referred to as a nozzle portion 31.
[0021]
Further, the bottom wall 28 is welded to the valve body 21 at the base 33 of the reinforcing rib 30, whereby the nozzle hole plate 26 is positioned in the axial direction. In this embodiment, as shown in FIG. 4A, the base portion 33 is formed by the laser beam irradiated obliquely with respect to the central axis O from the radially outer side of the reinforcing rib 30 toward the base portion 33 of the reinforcing rib 30. The entire circumference is welded to the downstream end of the valve body 21. As a result, as shown in FIG. 4B, the welded portion of the bottom wall 28 to the valve body 21 is continuous in the circumferential direction on the radially outer side of the outermost peripheral nozzle hole 29. By welding the bottom wall 28 in this way, the welding strength is ensured, and the fuel passes through the gap between the valve body 21 and the bottom wall 28 and passes through the gap between the valve body 21 and the peripheral wall 27 to the outside. To prevent leakage. Further, the base portion 33 of the reinforcing rib 30 is welded to the bottom wall 28, so that the welded portion is supported by the reinforcing rib 30 and the welding strength is increased. Further, by welding a relatively thin base 33 that is lower than the protruding height of the reinforcing rib 30 on the bottom wall 28, energy consumption during welding is reduced and welding time is shortened. This leads to a reduction in manufacturing costs and an increase in industrial productivity.
[0022]
The nozzle needle 36 as a valve member is accommodated coaxially on the inner peripheral side of the housing 11, the nozzle holder 20 and the valve body 21. The upstream end of the nozzle needle 36 is joined to the movable core 18 and can reciprocate integrally with the movable core 18. The downstream end of the nozzle needle 36 can be seated on the valve seat 24 of the valve body 21. When the nozzle needle 36 is seated on the valve seat portion 24, communication between the downstream end portion of the fuel passage 22 in the valve body 21 and each injection hole 29 of the injection hole plate 26 is blocked. On the other hand, when the nozzle needle 36 is separated from the valve seat portion 24, communication between the fuel passage 22 and each injection hole 29 is allowed. In this embodiment, as shown in FIG. 4, the downstream end face 36a of the nozzle needle 36 is formed in a substantially flat shape. Thereby, when the nozzle needle 36 is seated on the valve seat portion 24, the fuel surrounded by the downstream end surface 36 a of the nozzle needle 36, the inner wall surface 28 a of the bottom wall 28 of the nozzle hole plate 26, and the inner peripheral wall surface of the valve body 21. The space 35 has a flat truncated cone shape that is narrow in the axial direction and wide in the radial direction.
[0023]
The adjusting pipe 37 is press-fitted into the inner peripheral side of the fixed core 15 and forms a fuel passage therein. One end of the spring 38 is locked to the adjusting pipe 37, and the other end is locked to the movable core 18. The spring 38 biases the movable core 18 and the nozzle needle 36 in a direction approaching the valve seat portion 24. By adjusting the press-fitting amount of the adjusting pipe 37, the load of the spring 38 applied to the movable core 18 and the nozzle needle 36 can be changed.
[0024]
The filter 39 is installed on the upstream side of the fixed core 15 and removes foreign matters in the fuel supplied to the fuel injection device 10 from a fuel transfer pipe (not shown). The fuel that has flowed into the fixed core 15 through the filter 39 passes through the fuel passage in the adjusting pipe 37, the fuel passage in the movable core 18, the fuel passage formed by the outflow hole 19, the fuel passage in the nozzle holder 20, and the valve body 21. The fuel passage 22 is sequentially passed through.
[0025]
In the fuel injection device 10, when the movable core 18 is attracted toward the fixed core 15 by energization of the coil 41 and the nozzle needle 36 is separated from the valve seat portion 24 as shown in FIG. 5, the fuel passage 22 of the valve body 21. Communicates with each nozzle hole 29 and fuel is injected from each nozzle hole 29. At this time, fuel flows into the fuel space 35 on the downstream side from the gap 34 between the valve seat portion 24 and the nozzle needle 36. The fuel that has flowed into the fuel space 35 is guided by the downstream end surface 36 a of the nozzle needle 36 and the inner wall surface 28 a of the bottom wall 28 of the nozzle hole plate 26 toward the gap 34 between the valve seat portion 24 and the nozzle needle 36. Backflow. A turbulent flow is generated by the reverse flow from the fuel space 35 toward the gap 34 and the forward flow from the gap 34 toward the fuel space 35 colliding with each other. The fuel turbulent in this way flows into the nozzle hole 29 and is injected without being rectified through the nozzle hole 29, thereby promoting atomization of the fuel spray injected from the nozzle hole 29. Moreover, in the fuel injection device 10, at least the nozzle portion 31 of the bottom wall 28 of the nozzle hole plate 26 is made as thin as possible, so that the length of the nozzle hole 29 in the passage direction can be shortened. Thereby, since the rectifying action in the injection hole 29 is reduced, atomization of the fuel spray is further promoted.
[0026]
Further, in the fuel injection device 10, when the fuel flows into the fuel space 35, a fuel pressure of 5 to 12 MPa acts on the nozzle portion 31 of the bottom wall 28 of the nozzle hole plate 26 that covers the opening 23 of the valve body 21. However, in the fuel injection device 10, since the reinforcing rib 30 is formed on the radially outer side of the nozzle portion 31 of the nozzle hole plate 26, even when the nozzle portion 31 and the like of the bottom wall 28 are formed thin as described above, The deformation of the bottom wall 28 due to the fuel pressure is suppressed. In particular, in the fuel injection device 10, since the reinforcing ribs 30 are formed so as to be continuous in the circumferential direction of the bottom wall 28, the reinforcing action of the reinforcing ribs 30 is uniform in the circumferential direction, and the durability of the nozzle hole plate 26 is improved. It has been. As described above, in the fuel injection device 10, atomization of the spray can be promoted while ensuring the pressure strength of the nozzle hole plate 26 with respect to the fuel pressure with a smaller number of parts than before, so that the manufacturing cost can be reduced and industrial production can be achieved. It is possible to improve the performance.
[0027]
(Second embodiment)
A fuel injection device according to a second embodiment of the present invention is shown in FIG. Components that are substantially the same as those in the first embodiment are denoted by the same reference numerals.
In the fuel injection device 50 of the second embodiment, a thick part 52 thicker than the nozzle part 31 is provided on the bottom wall 28 of the nozzle hole plate 26 on the radially outer side of the nozzle part 31 where the nozzle hole 29 is formed. ing. The thick portion 52 is formed in a generally circular cross section around the axis O. A concave groove 54 that opens to the outer wall surface 28 b of the bottom wall 28 is provided in the radial intermediate portion of the thick portion 52. The concave groove 54 is formed in an annular shape that is continuous in the circumferential direction of the thick portion 52 with the axis O as the center. In the fuel injection device 50, the reinforcing rib 30 that is continuous in the circumferential direction of the bottom wall 28 is formed by the radially inner portion of the recessed groove 54 in the thick portion 52. Such a reinforcing rib 30 can be easily formed simply by forming the thick portion 52 using a drawing process and further forming the concave groove 54.
[0028]
Further, in the fuel injection device 50, the thickness of the bottom portion 56 of the concave groove 54 is set to be substantially the same as the thickness of the nozzle portion 31 in the thick portion 52 of the nozzle hole plate 26. The bottom wall 28 of the nozzle hole plate 26 is positioned in the axial direction by welding the bottom 56 of the groove 54 to the valve body 21. In this embodiment, as shown in FIG. 7A, the bottom 56 is welded to the downstream end of the valve body 21 over the entire circumference by a laser beam irradiated substantially parallel to the central axis O. . Accordingly, as shown in FIG. 7B, the welded portion of the bottom wall 28 is continuous in the circumferential direction on the radially outer side than the outermost peripheral nozzle hole 29. As described above, in the fuel injection device 50, the bottom portion 56 that is thinner than the other portions in the thick portion 52 of the bottom wall 28 is welded, that is, the bottom portion 56 that is lower than the protruding height of the reinforcing rib 30 is welded. The energy consumption during welding can be reduced and the welding time can be shortened. Therefore, according to the fuel injection device 50, the manufacturing cost can be reduced and the industrial productivity can be increased.
[0029]
In the embodiments described above, an example in which the present invention is applied to a fuel injection device that directly injects fuel into a combustion chamber of a gasoline engine has been described. However, the present invention is directed to fuel injection that injects fuel into an intake pipe of a gasoline engine. You may apply to an apparatus and may apply not only to a gasoline engine but to a diesel engine.
[0030]
In the above embodiments, the reinforcing ribs 30 that are continuous in the circumferential direction of the bottom wall 28 that is the cover wall of the nozzle hole plate 26 are formed. However, the reinforcing ribs that intermittently extend in the circumferential direction of the bottom wall 28 are formed. May be. When a plurality of reinforcing ribs extending intermittently in the circumferential direction are employed in the second embodiment, the reinforcing ribs are formed by intermittently forming a plurality of concave grooves 54 in the circumferential direction of the bottom wall 28. Can do.
Further, in the above embodiments, the reinforcing rib 30 is formed in a shape protruding toward the valve body side of the bottom wall 28 of the nozzle hole plate 26, but the reinforcing rib is formed in a shape protruding toward the valve body side of the bottom wall 28. May be.
[0031]
Furthermore, in the above-described embodiments, the welding location of the bottom wall 28 of the nozzle hole plate 26 to the valve body 21 is set to be continuous in the circumferential direction on the radially outer side of the outermost peripheral nozzle hole 29. May be set at a plurality of locations that intermittently surround the radially outer side of the outermost peripheral nozzle hole 29.
[0032]
Furthermore, in the first embodiment, the bottom wall 28 of the nozzle hole plate 26 is welded to the valve body 21 by laser beam irradiation from the radially outer side of the reinforcing rib 30 toward the base portion 33 of the reinforcing rib 30. As in the second embodiment, welding may be performed by irradiation with a laser beam parallel to the central axis O of the bottom wall 28. On the contrary, in the second embodiment, welding may be performed by irradiating a laser beam from the radially outer side of the reinforcing rib 30 toward the root portion 33 of the reinforcing rib 30. In the above embodiments, the locations 33 and 56 that are radially outward from the radially innermost edge of the reinforcing rib 30 on the bottom wall 28 of the nozzle hole plate 26 are welded to the valve body 21. In this case, if the height is lower than the protruding height of the reinforcing rib 30, a position that is radially inward from the radially innermost edge of the reinforcing rib 30 may be welded.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a fuel injection device according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a fuel injection device according to a first embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a state where the fuel injection device according to the first embodiment of the present invention is attached to an engine.
FIGS. 4A and 4B are a cross-sectional view and a bottom view showing a welded state of the nozzle hole plate and the valve body of the fuel injection device according to the first embodiment of the present invention. FIGS.
FIG. 5 is a cross-sectional view for explaining the operation of the fuel injection device according to the first embodiment of the present invention, corresponding to FIG. 1;
FIG. 6 is a cross-sectional view showing a main part of a fuel injection device according to a second embodiment of the present invention.
FIGS. 7A and 7B are a cross-sectional view and a bottom view showing a welded state of an injection hole plate and a valve body of a fuel injection device according to a second embodiment of the present invention. FIGS.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10,50 Fuel injection apparatus 11 Housing 15 Fixed core 18 Movable core 20 Nozzle holder 21 Valve body 21a End surface 22 Fuel passage 24 Valve seat part 26 Injection hole plate 27 Perimeter wall 28 Bottom wall (cover wall)
29 Injection hole 30 Reinforcement rib 31 Nozzle part 33 Base part 36 Nozzle needle (valve member)
52 Thick part 54 Groove 56 Bottom

Claims (7)

A cylindrical valve body forming a fuel passage;
An injection hole plate that has a cover wall that covers one axial end surface of the valve body, and that forms an injection hole in the cover wall that can communicate with the downstream end of the fuel passage;
A valve member accommodated in the fuel passage so as to allow and block communication between the fuel passage and the nozzle hole;
A fuel injection device comprising:
The cover wall is provided with a reinforcing rib formed to protrude in a counter valve body side of the cover wall,
Of the covering wall, a region radially inward of the reinforcing rib, a thin portion lower than the protruding height of the reinforcing rib and the portion where the nozzle hole is formed is a nozzle portion,
Of the covering wall, it is a region on the radially outer side of the reinforcing rib, and a thin portion lower than the protruding height of the reinforcing rib is a thin portion,
The base portion is a root portion of the reinforcing ribs, the fuel injection device according to claim Tei Rukoto welded to the valve body of the thin portion. The reinforcing rib is formed in a shape continuous in the circumferential direction,
2. The fuel injection device according to claim 1, wherein the base portion is welded to the downstream end portion of the valve body over the entire circumference thereof . The nozzle hole plate is formed in a bottomed cylindrical shape having a peripheral wall and a bottom wall, and one end portion in the axial direction of the valve body is fitted to the inner peripheral side of the peripheral wall, and the bottom wall forms the cover wall. The fuel injection device according to claim 1, wherein the fuel injection device is a fuel injection device.   4. The fuel injection device according to claim 1, wherein a welded portion of the cover wall with respect to the valve body is set to be continuous in a circumferential direction on a radially outer side than the nozzle hole.   The fuel injection device according to claim 1, wherein the reinforcing rib is formed so as to be continuous in a circumferential direction of the covering wall. The fuel according to any one of claims 1 to 5, wherein the covering wall is welded to the valve body by irradiation of a laser beam directed from the radially outer side of the reinforcing rib toward the root portion. Injection device. In the covering wall, a portion that is radially outward from the nozzle hole forms a thick part that is thicker than the nozzle part,
The thick wall portion includes a concave groove, the reinforcing rib is formed at a portion radially inward of the concave groove, and a bottom portion of the concave groove is welded to the valve body. The fuel injection device according to any one of 1 to 6.

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