Solenoid device and solenoid valve of fuel injection device

Abstract

To provide a solenoid device that has excellent cavitation wear resistance, and can keep reliability of operation, and a solenoid valve of a fuel injection device.SOLUTION: A solenoid device drives a valve unit of a solenoid valve provided in a fuel injection device by electromagnetic force, and comprises: a core formed in a cylindrical shape, and comprising a facing surface facing the valve unit; a coil wound in the core; and a concave part provided at a position overlapping with the valve unit when viewed from an axial direction of a center axis of the core, out of the facing surface of the core.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a solenoid device and an electromagnetic valve of a fuel injection device. [Background technology]

[0002] A common rail fuel injection system used in diesel engines and the like comprises a fuel pump, a common rail, and a fuel injection valve. The fuel pump draws fuel from a fuel tank, pressurizes it, and supplies it to the common rail as high-pressure fuel. The common rail maintains the high-pressure fuel supplied from the fuel pump at a predetermined pressure. The fuel injection valve injects the high-pressure fuel from the common rail into the combustion chamber of the diesel engine by opening and closing the injection valve.

[0003] The fuel injection valve has a solenoid valve that includes a solenoid device that generates electromagnetic force by passing an electric current through a coil wound around a core, and a valve unit formed using a magnetic material. Such a solenoid valve is configured to apply an elastic force to the valve unit to hold the fuel flow path, and when the solenoid device does not generate electromagnetic force, the elastic force holds the fuel flow path closed. When the solenoid device generates electromagnetic force, the electromagnetic force pulls the valve unit toward the core of the solenoid device, and the valve unit moves away from the flow path to open the flow path (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-101349 Summary of the Invention [Problem to be solved by the invention]

[0005] In the solenoid valve described above, for example, when the valve unit separates from the core, the gap between the valve unit and the core temporarily becomes negative pressure, which can cause cavitation. This cavitation collapses when the pressure in the gap between the valve unit and the core recovers, damaging part of the core. This can result in reduced operational reliability when the solenoid device is operated for a long period of time.

[0006] The present disclosure has been made in view of the above, and aims to provide a solenoid device and a solenoid valve of a fuel injection device that are excellent in resistance to cavitation wear and can maintain operational reliability. [Means for solving the problem]

[0007] The solenoid device of the present disclosure is a solenoid device that drives a valve unit of an electromagnetic valve provided in a fuel injection device by electromagnetic force, and includes a cylindrical core having an opposing surface facing the valve unit, a coil wound around the core, and a recess provided on the opposing surface of the core at a position that overlaps with the valve unit when viewed from the axial direction of the center axis of the core.

[0008] The solenoid valve of the fuel injection device according to the present disclosure comprises the above-described solenoid device, and a valve unit formed using a magnetic material, arranged opposite the opposing surface of the core, to which an elastic force is applied in a direction away from the core in the axial direction, and which presses the fuel flow passage to close it by the elastic force when no electromagnetic force is generated by the solenoid device, and which is drawn by the electromagnetic force to the core to a position where it contacts the opposing surface and moves away from the flow passage to open the flow passage when electromagnetic force is generated by the solenoid device. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a solenoid device and a solenoid valve of a fuel injection device that are excellent in resistance to cavitation wear and can maintain operational reliability. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an example of a fuel injection device according to this embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view showing an example of a fuel injection valve. [Figure 3] FIG. 3 is a vertical cross-sectional view showing an example of a solenoid valve. [Figure 4] FIG. 4 is a diagram showing an example of the solenoid device shown in FIG. 3 as viewed from the tip end side. [Figure 5] FIG. 5 is a diagram showing an example of a cross-sectional configuration of a recess. [Figure 6] FIG. 6 is a diagram showing an example of a cross-sectional configuration of a recess. [Figure 7] FIG. 7 is a diagram showing an example of a cross-sectional configuration of a recess. [Figure 8] FIG. 8 is a vertical cross-sectional view showing an example of the operation of the solenoid valve. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of a solenoid device and a solenoid valve for a fuel injection device according to the present disclosure will be described with reference to the drawings. Note that the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially identical.

[0012] Fig. 1 is a schematic diagram showing an example of a fuel injection device 10 according to the present embodiment. As shown in Fig. 1, the fuel injection device 10 is mounted on a diesel engine (internal combustion engine). The fuel injection device 10 includes a fuel pump 11, a common rail 12, and a plurality of fuel injection valves 13.

[0013] The fuel pump 11 is connected to a fuel tank 14 via a fuel line L11. The fuel pump 11 draws fuel stored in the fuel tank 14 through the fuel line L11 and pressurizes it to generate high-pressure fuel. The fuel pump 11 is connected to a common rail 12 via a high-pressure fuel line L12. The common rail 12 maintains the high-pressure fuel supplied from the fuel pump 11 at a predetermined pressure. The common rail 12 is connected to fuel injection valves 13 via multiple (four in this embodiment) fuel supply lines L13. The fuel injection valves 13 inject the high-pressure fuel from the common rail 12 into each cylinder (combustion chamber) of the diesel engine by opening and closing a solenoid valve.

[0014] Fig. 2 is a vertical cross-sectional view showing an example of fuel injection valve 13. As shown in Fig. 2, fuel injection valve 13 has a shape that extends in the axial direction of center axis AX, and has an injection unit 20 and a solenoid valve 40. In the following description of the configuration of fuel injection valve 13, the fuel injection port 30 side in the axial direction of center axis AX will be referred to as the tip side, and the solenoid valve 40 side will be referred to as the base side.

[0015] The injection unit 20 has a casing 21 and a piston valve 22. The casing 21 has a fuel inlet 24, an injection-side flow path 25, a control-side flow path 26, an injection-side pressure chamber 27, a control-side pressure chamber 28, a cylinder chamber 29, a fuel injection port 30, a fuel outlet 31, and a solenoid valve-side pressure chamber 32.

[0016] Fuel from the fuel supply line L13 flows into the fuel inlet 24. The injection-side flow path 25 connects the fuel inlet 24 to an injection-side pressure chamber 27. The control-side flow path 26 connects the fuel inlet 24 to a control-side pressure chamber 28.

[0017] The injection pressure chamber 27 is connected to a fuel injection port 30. The fuel injection port 30 is disposed at the end of the tip side of the casing 21, and injects fuel toward each cylinder of the diesel engine.

[0018] The control-side pressure chamber 28 is connected to a fuel outlet 31. The fuel outlet 31 is disposed at the end of the base end of the casing 21, and is connected to a solenoid valve-side pressure chamber 32. The solenoid valve-side pressure chamber 32 is connected to the solenoid valve 40 (a space 46d, which will be described later).

[0019] The cylinder chamber 29 is connected to the injection-side pressure chamber 27 and the control-side pressure chamber 28. The cylinder chamber 29 accommodates the piston valve 22. The cylinder chamber 29 is connected to the solenoid-valve-side pressure chamber 32 via a flow path 29a.

[0020] The piston valve 22 is housed in a cylinder chamber 29 and is provided so as to be movable toward the injection-side pressure chamber 27 or the control-side pressure chamber 28. The piston valve 22 has a spring seat member 22a, a control-side piston member 22b, a connecting member 22c, and a valve body 22d. The spring seat member 22a, the control-side piston member 22b, and the connecting member 22c are integral with each other. The spring seat member 22a receives an elastic force from an elastic member 23, which will be described later. The control-side piston member 22b receives pressure from the control-side pressure chamber 28. The connecting member 22c connects the spring seat member 22a and the control-side piston member 22b. The valve body 22d protrudes from the spring seat member 22a toward the tip side in the axial direction of the central axis AX. The valve body 22d abuts against the spring seat member 22a due to the resultant force of the elastic force and the pressures received from the pressure chambers. The valve body 22d is formed in a shape such that the tip thereof can close the fuel injection port 30. The valve body 22d receives the pressure of the injection side pressure chamber 27.

[0021] When the pressure in the injection-side pressure chamber 27 is smaller than the resultant force of the pressure in the control-side pressure chamber 28 and the elastic force of the elastic member 23, the piston valve 22 is pressed toward the injection-side pressure chamber 27. In this case, the fuel injection port 30 is closed by the valve body 22d. From this state, when the pressure in the injection-side pressure chamber 27 becomes larger than the resultant force of the pressure in the control-side pressure chamber 28 and the elastic force of the elastic member 23, the piston valve 22 is pressed toward the control-side pressure chamber 28. In this case, the valve body 22d moves away from the fuel injection port 30, opening the fuel injection port 30.

[0022] The solenoid valve 40 has a solenoid device 41 and a valve unit 42. Fig. 3 is a longitudinal cross-sectional view showing an example of the solenoid valve 40. Fig. 3 shows an enlarged portion of Fig. 2. As shown in Fig. 3, the solenoid device 41 drives the valve unit 42 along the axial direction of the central axis AX by electromagnetic force. The solenoid device 41 has a core 43, a coil 44, a casing 45, a cylindrical member 46, and a terminal fixing member 47.

[0023] The core 43 has a magnetic material portion 50 and a sealing portion 49. The magnetic material portion 50 has a tubular portion 43a, a flange portion 43b, and a side surface portion 43c. The tubular portion 43a is formed, for example, in a cylindrical shape. The flange portion 43b is, for example, in a disk shape, and is disposed on the base end side of the core 43. The tubular portion 43a and the flange portion 43b are disposed so that their central axes coincide with the central axis AX of the fuel injection valve 13.

[0024] The side surface portion 43c is cylindrical and encloses the cylindrical portion 43a. The side surface portion 43c is disposed radially apart from the cylindrical portion 43a and extends toward the tip side. The cylindrical portion 43a, the flange portion 43b, and the side surface portion 43c are formed using a magnetic material (magnetic material portion 50). The core 43 accommodates the coil 44 in a space portion 43e surrounded by the cylindrical portion 43a, the flange portion 43b, and the side surface portion 43c. In other words, the cylindrical portion 43a, the flange portion 43b, and the side surface portion 43c form the magnetic material portion 50, which has an annular space portion 43e when viewed in the axial direction of the center axis AX and is open toward the valve unit 42, accommodates the coil 44, and has a circular space portion 43e. When viewed as a single unit, the core 43 appears to have the space portion 43e, but in reality, the coil 44 is disposed therein. The space portion 43e in which the coil 44 is disposed is sealed by a sealing portion 49. The sealing portion 49 is formed using, for example, a resin material. The core 43 has an opposing surface 43h that faces the valve unit 42, which will be described later. The opposing surface 43h is disposed at the end portion on the tip side of the core 43. In this embodiment, the end portion on the tip side of the cylindrical portion 43a, the end portion on the tip side of the side surface portion 43c, and the end portion on the tip side of the sealing portion 49 form the opposing surface 43h.

[0025] The sealing portion 49 has a recess 43f on its end surface on the tip side. The recess 43f is formed such that a portion of the sealing portion 49 is recessed toward the base end side. FIG. 4 is a diagram showing an example of the solenoid device 41 shown in FIG. 3 as viewed from the tip side. As shown in FIG. 4, the recess 43f has an annular shape centered on the central axis AX as viewed in the axial direction of the central axis AX. The recess 43f is provided around the entire circumference of the central axis AX. As viewed in the axial direction of the central axis AX, the recess 43f is positioned so as to overlap a through hole 42d of a valve unit 42, which will be described later.

[0026] 5 to 7 are diagrams showing examples of the cross-sectional configuration of the recess 43f. As shown in FIG. 5, the recess 43f may be formed in a state in which both radial sides of the sealing portion 49 remain. With this configuration, the space 43e can be sealed more reliably on both radial sides of the sealing portion 49. As shown in FIG. 6, the recess 43f may be formed to a uniform depth over the entire radial direction. With this configuration, the area of ​​the recess 43f can be sufficiently secured on the end face of the tip side of the core 43 when viewed from the axial direction of the central axis AX. As shown in FIG. 7, in addition to the configuration of FIG. 6, the core 43 may have a chamfered portion 43g at the end of the space 43e on the tip side in the axial direction of the central axis AX. The chamfered portion 43g is provided on the outer circumferential side of the cylindrical portion 43a and the inner circumferential side of the side surface portion 43c. The chamfered portion 43g is provided on the base end facing the space 43e. end side It has a tapered shape that slopes downward.

[0027] 3, the coil 44 is wound around the cylindrical portion 43a. The coil 44 passes through a casing 45 (described later) and is connected to a power supply (not shown). The solenoid device 41 generates an electromagnetic force by passing a current through the coil 44.

[0028] The casing 45 accommodates the core 43 and the coil 44. The casing 45 is formed, for example, from a resin material. The casing 45 has a support portion 45a that supports an elastic member 48, which will be described later. The terminal fixing member 47 is disposed between the core 43 and the casing 45, which will be described later, in the axial direction of the central axis AX, and fixes a terminal 44a that is connected to the coil 44. The terminal 44a penetrates the casing 45 and is drawn out to the outside. The terminal fixing member 47 is formed, for example, from a resin material.

[0029] The cylindrical member 46 is disposed on the inner peripheral side of the core 43. The cylindrical member 46 is formed using, for example, a metal material. The cylindrical member 46 may be made of a non-magnetic metal. The cylindrical member 46 is, for example, cylindrical, and is disposed so that its central axis coincides with the central axis AX of the fuel injection valve 13. The cylindrical member 46 is disposed at a position where a tip end face 46b can come into contact with the valve unit 42. In this embodiment, the end face 46b is flush with, for example, the tip end face of the side portion 43c of the core 43 and the tip end face of the sealing portion 49.

[0030] The elastic member 48 is housed on the inner peripheral side of the cylindrical member 46 with its base end supported by the support portion 45a of the casing 45. The elastic member 48 applies an elastic force to the valve unit 42 toward the tip side in the axial direction of the center axis AX.

[0031] The valve unit 42 moves in the axial direction of the central axis AX by electromagnetic force generated by the solenoid device 41. The valve unit 42 has an armature 42a, a valve body 42b, a step portion 42c, and a through hole 42d. The armature 42a is formed using a magnetic material. The armature 42a is, for example, disk-shaped. The armature 42a is disposed opposite the tip end of the core 43 of the solenoid device 41. The valve body 42b extends from the armature 42a toward the tip end. The tip end of the valve body 42b is formed in a shape that can close the fuel discharge port 31. The valve body 42b may be formed of a magnetic material or a non-magnetic material.

[0032] The through holes 42d are provided so as to penetrate the armature 42a in the axial direction of the center axis AX. When viewed from the axial direction of the center axis AX, the through holes 42d are arranged at intervals in the direction around the center axis AX. In this embodiment, as shown by the dashed dotted line in FIG. 4, for example, the through holes 42d are arranged at 90° angles around the center axis AX, but the present invention is not limited to this configuration.

[0033] The operation of the fuel injection valve 13 configured as described above will now be described. When no current flows through the coil 44 of the solenoid device 41, no electromagnetic force is generated in the solenoid device 41. In this case, the valve body 42b of the valve unit 42 presses the fuel outlet 31 toward the tip side due to the elastic force of the elastic member 48. This causes the fuel outlet 31 to be closed.

[0034] When the fuel outlet 31 is closed, the resultant force of the pressure received by the control-side pressure chamber 28 and the elastic force of the elastic member 23 becomes greater than the pressure received by the injection-side pressure chamber 27. As a result, the piston valve 22 presses the fuel injection port 30, thereby closing it.

[0035] Furthermore, when a current is passed through the coil 44 of the solenoid device 41, an electromagnetic force is generated in the solenoid device 41. Fig. 8 is a vertical cross-sectional view showing an example of the operation of the solenoid valve 40. Fig. 8 shows an example when a current is passed through the coil 44. As shown in Fig. 8, when an electromagnetic force is generated in the solenoid device 41, the armature 42a of the valve unit 42 is attracted toward the core 43 by the electromagnetic force, and the valve body 42b moves away from the fuel discharge port 31. This opens the fuel discharge port 31.

[0036] When the fuel outlet 31 opens, the pressure in the control-side pressure chamber 28 decreases. When the resultant force of the pressure received by the control-side pressure chamber 28 and the elastic force of the elastic member 23 becomes smaller than the pressure received by the injection-side pressure chamber 27, the piston valve 22 moves toward the control-side pressure chamber 28. In this case, the valve body 22d of the piston valve 22 moves away from the fuel injection port 30, and the fuel injection port 30 opens. When the fuel injection port 30 opens, fuel that has flowed from the fuel inlet 24 through the injection-side flow path 25 and into the injection-side pressure chamber 27 is injected from the fuel injection port 30.

[0037] In the above operation, when the valve unit 42 is attracted toward the core 43 by the electromagnetic force of the solenoid device 41, the step 42c of the valve unit 42 comes into contact with the end surface 46b of the cylindrical member 46, as shown in Fig. 8. In this case, the cylindrical member 46 functions as a stopper that restricts the movement of the valve unit 42 toward the base end.

[0038] After the step 42c of the valve unit 42 comes into contact with the end face 46b of the cylindrical member 46, the electromagnetic force of the solenoid device 41 is turned off, whereby the valve unit 42 is pressed toward the tip end in the axial direction of the central axis AX by the elastic force of the elastic member 48, and the valve unit 42 is separated from the core 43 so that the valve body 42b seals the fuel discharge port 31. In the present embodiment, a recess 43f is provided in the end face on the tip side of the core 43, thereby ensuring a region between the core 43 and the valve unit 42 in which fuel can be placed. By providing this region, the occurrence of cavitation is suppressed when the valve unit 42 moves in a direction away from the core 43, and therefore damage to the core 43 due to cavitation is suppressed.

[0039] As described above, the solenoid device 41 according to this embodiment is a solenoid device 41 that drives the valve unit 42 of the electromagnetic valve 40 provided in the fuel injection device 10 by electromagnetic force, and includes a cylindrical core 43 having an opposing surface 43h that faces the valve unit 42, a coil 44 wound around the core 43, and a recess 43f provided on the opposing surface 43h of the core 43 at a position that overlaps with the valve unit 42 when viewed from the axial direction of the center axis AX of the core 43.

[0040] According to this configuration, recess 43f is provided in the end face on the tip side of core 43, so an area in which fuel can be placed is secured between core 43 and valve unit 42. By providing this area, the occurrence of cavitation is suppressed, for example, when valve unit 42 moves in a direction away from core 43, and therefore damage to core 43 due to cavitation is suppressed. This makes it possible to provide solenoid device 41 that is excellent in resistance to cavitation wear and can maintain operational reliability.

[0041] In the solenoid device 41 according to this embodiment, the recess 43f has an annular shape centered on the central axis AX when viewed in the axial direction of the central axis AX. This configuration ensures an area in which fuel can be placed over the entire axial direction of the central axis AX, thereby more reliably suppressing the occurrence of cavitation.

[0042] In the solenoid device 41 according to this embodiment, the core 43 has a magnetic part 50 formed using a magnetic material, which is open on the valve unit 42 side and houses the coil 44, and which has an annular space 43e when viewed from the axial direction, and a sealing part 49 formed using a resin material and sealing the space 43e, and the recess 43f is provided in the sealing part 49. With this configuration, the recess 43f is provided in a part of the core 43 that does not affect the generation of electromagnetic force, so that the occurrence of cavitation can be suppressed without reducing the drivability of the valve unit 42.

[0043] In the solenoid device 41 according to this embodiment, the magnetic body 50 has a chamfered portion 43g at the end of the space 43e on the axial side of the valve unit 42. This configuration can more reliably suppress the occurrence of cavitation.

[0044] The solenoid valve 40 of the fuel injection device 10 according to this embodiment comprises the above-mentioned solenoid device 41, and a valve unit 42 formed using a magnetic material, arranged opposite the opposing surface 43h of the core 43, and to which an elastic force is applied in a direction away from the core 43 in the axial direction, and when no electromagnetic force is generated by the solenoid device 41, the elastic force presses the fuel flow passage to close it, and when an electromagnetic force is generated by the solenoid device 41, the electromagnetic force pulls the core 43 to a position where it contacts the opposing surface 43h, and moves away from the flow passage, thereby opening the flow passage.

[0045] According to this configuration, by suppressing the occurrence of cavitation when the valve unit 42 is driven, damage to the core 43 due to cavitation is suppressed, and the solenoid device 41 is provided which can maintain operational reliability, so that, for example, a long-life solenoid valve 40 can be obtained.

[0046] In the solenoid valve 40 of the fuel injection device 10 according to this embodiment, the valve unit 42 has an armature 42a facing the opposing surface 43h and a valve element 42b extending axially from the armature 42a, the armature 42a has a through-hole 42d penetrating therethrough in the axial direction, and the recess 43f is disposed at a position overlapping the through-hole 42d as viewed from the axial direction. With this configuration, the recess 43f is in communication with the tip side of the valve unit 42 via the through-hole 42d, so that the occurrence of cavitation when the valve unit 42 moves can be more reliably suppressed.

[0047] The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the solenoid valve 40 is provided in the fuel injection valve 13 of the fuel injection device 10, but the present invention is not limited to this. The solenoid valve 40 may be provided in another location in the fuel injection device 10.

[0048] Furthermore, the configuration of the fuel injection device 10 and the configuration of the fuel pump 11 are not limited to the above-described embodiment. For example, the number of the common rail 12 and the fuel injection valves 13, the connection position of the fuel pump 11, etc. can be set as appropriate. [Explanation of symbols]

[0049] 10 Fuel injection device 11 Fuel pump 12 Common rail 13 Fuel injection valve 14 Fuel Tank 20 Injection part 21,45 casing 22 Piston valve 22a Spring seat member 22b Control side piston member 22c Connecting member 22d, 42b Valve body 23,48 Elastic member 24 Fuel inlet 25 Injection side flow path 26 Control side flow path 27 Injection side pressure chamber 28 Control side pressure chamber 29 Cylinder chamber 30 Fuel injection port 31 Fuel outlet 32 Solenoid valve side pressure chamber 40 Solenoid valve 41 Solenoid device 42 Valve unit 42a Armature 42c Stepped section 42d through hole 43 cores 43a Cylindrical part 43b Flange part 43c side Department 4 3e Space section 43g chamfered part 43h Opposite surface 44 coils 45a Support part 46 Cylindrical member 46b End face 47 Terminal fixing member 49 Sealing part 43f recess 50 Magnetic body part AX center axis L11 fuel line L12 fuel high pressure line L13 Fuel supply line

Claims

1. A solenoid device that drives a valve unit of an electromagnetic valve provided in a fuel injection device by electromagnetic force, a core formed in a cylindrical shape and having an opposing surface facing the valve unit; a cylindrical member disposed on an inner circumferential surface of the core; a coil wound around the core; a recess provided on the opposing surface of the core at a position overlapping with the valve unit when viewed in the axial direction of the central axis of the core; Equipped with the core has a magnetic material portion formed using a magnetic material, opening toward the valve unit, accommodating the coil, and having an annular space portion as viewed from the axial direction; and a sealing portion formed using a resin material and sealing the space portion, the recess is provided in the sealing portion by recessing at least a part of the sealing portion from an end face of the sealing portion on the valve unit side in the axial direction, while leaving both radial sides of the sealing portion, When the valve unit is attracted to the core by the electromagnetic force of the solenoid device and comes into contact with the cylindrical member, the cylindrical member functions as a stopper that restricts movement of the valve unit in the axial direction. Solenoid device.

2. The recessed portion is annular with the central axis as the center when viewed in the axial direction. The solenoid device according to claim 1 .

3. The magnetic body portion has a chamfered portion at an end of the space portion on the valve unit side in the axial direction. The solenoid device according to claim 1 .

4. The solenoid device according to any one of claims 1 to 3; a valve unit formed using a magnetic material, disposed opposite the opposing surface of the core, to which an elastic force is applied in a direction away from the core in the axial direction, and which presses the fuel flow passage by the elastic force to close the passage when no electromagnetic force is generated by the solenoid device, and which is drawn to the core by the electromagnetic force to a position where it contacts the opposing surface and moves away from the passage to open the passage when an electromagnetic force is generated by the solenoid device; A solenoid valve of a fuel injection device comprising:

5. the valve unit includes an armature facing the opposing surface and a valve body extending from the armature in the axial direction, the armature has a through hole that penetrates in the axial direction, The recess is disposed at a position overlapping the through hole when viewed in the axial direction.

5. The solenoid valve of a fuel injection system according to claim 4.

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