WO2017154815A1

WO2017154815A1 - Fuel injection device

Info

Publication number: WO2017154815A1
Application number: PCT/JP2017/008691
Authority: WO
Inventors: 孝一望月; 松本　修一; 英人武田
Original assignee: 株式会社デンソー
Priority date: 2016-03-10
Filing date: 2017-03-06
Publication date: 2017-09-14
Also published as: JP2017160862A; JP6613973B2; DE112017001210T5

Abstract

A fuel injection device (1) is provided with: a nozzle (10) having a nozzle hole (11) from which fuel is injected and a valve seat (12) which is formed around the nozzle hole; a cylindrical housing (20) having one end connected to the nozzle, the cylindrical housing (20) having a fuel passage (100) which is formed inside so as to be in communication with the nozzle hole and which conducts fuel to the nozzle hole; a needle (30) provided so as to be capable of reciprocating inside the housing and configured so as to open the valve when one end of the needle (30) moves away from the valve seat and to close the valve when said end is in contact with the valve seat; a plurality of movable cores (40, 50) provided so as to be capable or incapable of moving relative to the needle; a stationary core (70) provided on the opposite side of the movable cores from the valve seat; and a coil (80) which, when an electric current is conducted thereto, generates a magnetic flux to attract the movable cores toward the stationary core, thereby being capable of moving the needle to the side opposite the valve seat. An annular inter-movable-core gap (s1) is formed between the stationary core-side surface (421) of one movable core (40) of the plurality of movable cores and the valve seat-side surface (512) of the other movable core (50), which is different from said movable core.

Description

Fuel injection device

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2016-46914 filed on Mar. 10, 2016, the contents of which are incorporated herein by reference.

The present disclosure relates to a fuel injection device that injects and supplies fuel to an internal combustion engine.

Conventionally, a fuel injection device in which a plurality of movable cores are provided for one needle is known. For example, in Patent Document 1, two movable cores are provided for one needle to realize two needle lift amounts.

JP 2014-141924 A

In the fuel injection device of Patent Document 1, the first movable core is provided so as to be relatively movable with respect to the needle, and the second movable core is provided so as not to be relatively movable with respect to the needle. In this fuel injection device, when the coil is not energized, that is, when the needle is in contact with the valve seat and is closed, the first movable core and the second movable core are opposed to each other. Touching. Therefore, the magnetic resistance between the first movable core and the second movable core is small. In this configuration, when the coil is energized, a magnetic flux flows through the first movable core, and a large amount of magnetic flux also flows through the second movable core. For this reason, the force for sucking the first movable core toward the fixed core may be reduced. Thereby, especially when the fuel pressure in the fuel injection device is high, there is a possibility that the needle cannot be properly opened at the initial stage of energization of the coil. On the other hand, when the coil is energized to such an extent that the needle can be sufficiently opened, power consumption at the initial energization may increase.

Further, in the fuel injection device of Patent Document 1, the opposing surfaces of the first movable core and the second movable core that are in contact with each other at the time of a large stroke of the needle are separated from each other, and a gap is formed therebetween. . Therefore, at this time, there is a possibility that a ringing force, which is a force for preventing separation from each other, is generated between the opposing surfaces. As a result, the valve opening speed of the needle decreases, and a sufficient needle lift amount may not be achieved. Therefore, the fuel injection accuracy may be reduced.

Further, in the fuel injection device of Patent Document 1, when the needle is closed, that is, in contact with the valve seat in a state where the opposing surfaces of the first movable core and the second movable core are in contact with each other, the first Ringing force is generated between the opposing surfaces of the movable core and the second movable core, and the collision energy when the needle comes into contact with the valve seat may increase. This may cause the needle to bounce at the valve seat and cause an unintended secondary valve opening. Therefore, the fuel injection accuracy may be reduced.

Further, in the fuel injection device of Patent Document 1, when the needle is opened, the first movable core and the second movable core are in contact with the fixed core at the surfaces facing the fixed core. Therefore, when energization of the coil is stopped and the needle is closed, the influence of the residual magnetism of the fixed core reaches the first movable core and the second movable core, and the fixed core, the first movable core, and the first movable core A ringing force may be generated between the two movable cores, and the first movable core and the second movable core may remain in contact with the fixed core. This may delay the closing of the needle. Therefore, the fuel injection accuracy may be reduced.

The present disclosure has been made in view of the above-described problems, and an object thereof is to provide a fuel injection device that can inject high-pressure fuel with high accuracy.

In order to achieve the above object, the fuel injection device according to the first aspect of the present disclosure includes a nozzle, a housing, a needle, a movable core, a fixed core, and a coil. The nozzle has an injection hole through which fuel is injected and a valve seat formed around the injection hole. The housing is formed in a cylindrical shape, has one end connected to the nozzle, and has a fuel passage formed inside so as to communicate with the nozzle hole and guiding fuel to the nozzle hole. The needle is provided so as to be reciprocally movable inside the housing, and opens when one end is separated from the valve seat and closes when one end contacts the valve seat. A plurality of movable cores are provided so as to be movable relative to the needle or not movable relative to the needle. The fixed core is provided on the side opposite to the valve seat with respect to the movable core. When the coil is energized, it generates a magnetic flux, and it is possible to attract the movable core toward the fixed core and move the needle away from the valve seat.

And in this aspect, an annular movable core is provided between the surface on the fixed core side of one movable core and the surface on the valve seat side of the other movable core different from the one movable core. A gap is formed. Therefore, the magnetic resistance between the plurality of movable cores can be increased. As a result, when energizing the coil, a large amount of magnetic flux can flow through a part of the plurality of movable cores, and the attractive force between the movable core and the fixed core can be increased. Therefore, even when the fuel pressure in the fuel passage is high, the needle can be opened. Therefore, in this aspect, high-pressure fuel can be injected.

Further, in this aspect, since the annular gap between the movable cores is formed between the plurality of movable cores, the ringing force generated when the movable cores are about to be separated can be reduced. Therefore, it is possible to suppress a decrease in the valve opening speed of the needle and an unintended secondary valve opening that may occur in the conventional fuel injection device. Therefore, in this aspect, fuel can be injected with high accuracy.

In order to achieve the above object, the fuel injection device according to the second aspect of the present disclosure includes a nozzle, a housing, a needle, a movable core, a fixed core, and a coil. In this aspect, the housing or the fixed core has a contact surface that can contact the surface of the fixed core or the needle of at least one of the plurality of movable cores. An annular inter-core gap is formed between the movable core and the fixed core when the surface of the movable core on the fixed core side or the needle and the contact surface contact each other. Therefore, when energization to the coil is stopped and the needle is closed, the influence of the remanent magnetism of the fixed core on the movable core and ringing force between the fixed core and the movable core are suppressed. can do. Thereby, it can suppress that a movable core will be in the state which contact | abutted to the fixed core. Therefore, the needle can be quickly closed after energization of the coil is stopped. Therefore, in this aspect, fuel can be injected with high accuracy.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
The typical sectional view showing the fuel injection device by a 1st embodiment. It is typical sectional drawing which shows the fuel-injection apparatus by 1st Embodiment, Comprising: The figure which shows the state by the initial stage of electricity supply to a coil. It is a typical sectional view showing the fuel injection device by a 1st embodiment, and is a figure showing the state after the state of Drawing 2. FIG. 4 is a schematic cross-sectional view showing the fuel injection device according to the first embodiment, and shows a state after the state of FIG. 3. FIG. 5 is a schematic cross-sectional view showing the fuel injection device according to the first embodiment, and shows a state after the state of FIG. 4. FIG. 6 is a schematic cross-sectional view showing the fuel injection device according to the first embodiment, and shows a state after the state of FIG. 5. It is a typical sectional view showing the fuel injection device by a 1st embodiment, and is a figure showing the state after the state of Drawing 6. The typical sectional view showing the fuel injection device by a 2nd embodiment. It is a typical sectional view showing the fuel injection device by a 2nd embodiment, and is a figure showing the state different from the state of Drawing 8. The typical sectional view showing the fuel injection device by a 3rd embodiment. It is a typical sectional view showing the fuel injection device by a 3rd embodiment, and is a figure showing the state different from the state of Drawing 10. Typical sectional drawing which shows the fuel-injection apparatus by 4th Embodiment.

Hereinafter, a fuel injection device according to a plurality of embodiments will be described with reference to the drawings. Note that, in a plurality of embodiments, substantially the same components are denoted by the same reference numerals, and description thereof is omitted.

(First embodiment)
A fuel injection device according to a first embodiment is shown in FIGS. The fuel injection device 1 is used, for example, in a direct injection gasoline engine as an internal combustion engine (not shown), and injects and supplies gasoline as fuel to the engine.

As shown in FIG. 1, the fuel injection device 1 includes a nozzle 10, a housing 20, a needle 30, a first movable core 40 and a second movable core 50 as movable cores, a fixed core 70, a coil 80, and a first biasing member. And a spring 92 as a second urging member.

The nozzle 10 is formed in a substantially disc shape by a magnetic material such as ferritic stainless steel. The nozzle 10 has a nozzle hole 11 and a valve seat 12. The nozzle hole 11 is formed so as to penetrate the center of the nozzle 10 in the plate thickness direction. The valve seat 12 is formed in an annular shape around the nozzle hole 11 on one surface of the nozzle 10. The nozzle 10 has a tapered surface on which the valve seat 12 is formed.

The housing 20 includes a first cylinder part 21, a second cylinder part 22, and a nonmagnetic member 60. Like the nozzle 10, the 1st cylinder part 21 and the 2nd cylinder part 22 are formed in the cylinder shape, for example with magnetic materials, such as ferritic stainless steel. The 1st cylinder part 21 is formed in the substantially cylindrical shape. The 2nd cylinder part 22 is formed in the substantially cylindrical shape. The inner diameter and outer diameter of the second cylindrical portion 22 are larger than the inner diameter and outer diameter of the first cylindrical portion 21. The 1st cylinder part 21 and the 2nd cylinder part 22 are integrally formed so that it may become coaxial. A step surface 201 is formed on the inner wall between the first tube portion 21 and the second tube portion 22.

The housing 20 is formed integrally with the nozzle 10 such that the opposite side of the first cylinder portion 21 to the second cylinder portion 22 is connected to the outer edge portion of the surface of the nozzle 10 on the valve seat 12 side. That is, in the present embodiment, the first cylindrical portion 21 and the second cylindrical portion 22 of the housing 20 and the nozzle 10 are integrally formed of the same material. A fuel passage 100 communicating with the injection hole 11 is formed inside the housing 20.

The needle 30 is formed in a rod shape from a nonmagnetic material such as austenitic stainless steel. The needle 30 has a needle main body 31 and a collar portion 32. The needle body 31 is formed in a substantially cylindrical shape. One end surface of the needle body 31 is formed in a tapered shape, and a seal portion 33 is formed on the outer edge portion. Further, the needle body 31 is formed with an axial hole 34 and a radial hole 35. The axial hole 34 is formed to extend from the end surface of the needle body 31 opposite to the seal portion 33 toward the seal portion 33 in the axial direction. The radial hole 35 extends in the radial direction of the needle body 31 and is formed to open to the outer wall of the needle body 31. The radial hole portion 35 is connected to the end portion of the axial hole portion 34 on the seal portion 33 side.

The collar portion 32 is formed in a substantially cylindrical shape so as to protrude radially outward from the outer wall at the end opposite to the seal portion 33 of the needle body 31. In the present embodiment, the collar portion 32 is formed integrally with the needle body 31. The end surface of the collar portion 32 opposite to the seal portion 33 is on the same plane as the end surface of the needle body 31 opposite to the seal portion 33.

The needle 30 is provided so that it can reciprocate in the axial direction inside the housing 20, and the seal portion 33 can come into contact with the valve seat 12. Here, the needle 30 opens when the seal portion 33 is separated from the valve seat 12 and closes when the seal portion 33 contacts the valve seat 12. When the needle 30 opens or closes, the nozzle hole 11 opens and closes. Hereinafter, the direction in which the needle 30 is separated from the valve seat 12 is referred to as a valve opening direction, and the direction in which the needle 30 contacts the valve seat 12 is referred to as a valve closing direction.

The fuel injection device 1 according to the present embodiment includes two movable cores (first movable core 40 and second movable core 50). The first movable core 40 is formed of a magnetic material such as ferritic stainless steel. The first movable core 40 has a cylinder part 41 and a bottom part 42. The cylinder part 41 is formed in a substantially cylindrical shape. The bottom portion 42 is formed in a substantially disc shape, and is formed integrally with the cylinder portion 41 so as to close one end portion of the cylinder portion 41. In the bottom portion 42, a recess 43, an insertion hole 44, and a communication hole 45 are formed. The recessed portion 43 is formed so as to be recessed from the center of the surface of the bottom portion 42 opposite to the tubular portion 41 toward the tubular portion 41 side. The insertion hole portion 44 is formed so as to connect the center of the surface 421 of the bottom portion 42 on the cylinder portion 41 side and the center of the recess 43. The communication hole 45 is formed so as to connect the surface 421 of the bottom portion 42 on the cylindrical portion 41 side and the concave portion 43. A plurality of communication holes 45 are formed at equal intervals in the circumferential direction of the bottom 42 on the radially outer side of the insertion hole 44. In the present embodiment, for example, four communication holes 45 are formed.

The first movable core 40 is provided such that the needle body 31 is inserted into the insertion hole 44 and is movable relative to the needle body 31 in the axial direction. In the first movable core 40, the outer portion of the insertion hole 44 of the surface 421 on the cylinder portion 41 side of the bottom portion 42 can contact the end surface of the flange portion 32 on the valve seat 12 side. In the first movable core 40, the inner wall of the insertion hole 44 can slide with the outer wall of the needle body 31. That is, the first movable core 40 is provided so as to be movable relative to the needle 30. As for the 1st movable core 40, the outer wall of the cylinder part 41 and the bottom part 42 is slidable with the inner wall of the 2nd cylinder part 22 of the housing 20. As shown in FIG.

As with the first movable core 40, the second movable core 50 is formed of a magnetic material such as ferritic stainless steel. The second movable core 50 has a movable core body 51. The movable core body 51 is formed in a substantially cylindrical shape. The movable core body 51 is provided such that the inner wall is fitted to the outer wall of the flange portion 32. In the present embodiment, the movable core body 51 is fixed to the flange portion 32 by, for example, press fitting or welding. That is, the second movable core 50 is provided so as not to move relative to the needle 30. Therefore, the second movable core 50 reciprocates integrally with the needle 30 inside the housing 20.

Here, the length of the movable core body 51 in the axial direction is smaller than the length of the flange portion 32 in the axial direction. The end surface of the movable core body 51 opposite to the valve seat 12 is on the same plane as the end surface of the collar portion 32 opposite to the valve seat 12. Therefore, the end surface on the valve seat 12 side of the collar portion 32 is located on the valve seat 12 side with respect to the end surface on the valve seat 12 side of the movable core body 51 of the second movable core 50. Between the surface 412 of the bottom portion 42 of the first movable core 40 on the cylinder portion 41 side and the end surface 512 of the movable core body 51 of the second movable core 50 on the valve seat 12 side, a substantially annular gap s1 between the movable cores. Is formed. The size of the gap s1 between the movable cores in the axial direction varies depending on the position of the first movable core 40 with respect to the needle body 31, and the bottom 42 of the first movable core 40 abuts on the end face of the flange 32 on the valve seat 12 side. The minimum. Thus, regardless of whether or not the bottom portion 42 of the first movable core 40 is in contact with the end surface of the flange portion 32 on the valve seat 12 side, the surface 421 of the bottom portion 42 on the tube portion 41 side and the movable core main body 51. The end face 512 on the valve seat 12 side is always separated from each other, and a movable core gap s1 is formed therebetween. The communication hole 45 of the first movable core 40 communicates with the inter-movable core gap s 1 and connects the inter-movable core gap s 1 and the space inside the recess 43.

In the present embodiment, the axial length of the cylindrical portion 41 of the first movable core 40 is larger than the axial length of the flange portion 32. Therefore, when the bottom portion 42 of the first movable core 40 is in contact with the end surface of the flange portion 32 on the valve seat 12 side, the end surface of the cylinder portion 41 opposite to the valve seat 12 is movable with respect to the second movable core 50. The core body 51 is located on the side opposite to the valve seat 12 with respect to the end surface on the side opposite to the valve seat 12. In the present embodiment, in the second movable core 50, the outer wall of the movable core body 51 can slide with the inner wall of the cylindrical portion 41 of the first movable core 40. The nonmagnetic member 60 of the housing 20 is formed in a cylindrical shape from a nonmagnetic material such as austenitic stainless steel. The nonmagnetic member 60 forms a magnetic diaphragm portion.

The nonmagnetic member 60 is provided on the side opposite to the nozzle 10 with respect to the second cylindrical portion 22. The nonmagnetic member 60 has a nonmagnetic cylindrical portion 61 and a nonmagnetic protruding portion 62. The nonmagnetic cylinder portion 61 is formed in a substantially cylindrical shape. The nonmagnetic projecting portion 62 is formed in a substantially cylindrical shape so as to project radially inward from the inner wall of one end portion of the nonmagnetic tubular portion 61. The nonmagnetic protrusion 62 is formed integrally with the nonmagnetic cylinder 61. The non-magnetic member 60 includes a second cylinder such that an end of the non-magnetic cylinder 61 opposite to the non-magnetic protrusion 62 is connected to an end of the second cylinder 22 opposite to the first cylinder 21. It is provided coaxially with the portion 22. The nonmagnetic member 60 and the second cylindrical portion 22 are connected by welding, for example.

The fixed core 70 is provided on the opposite side of the valve seat 12 with respect to the first movable core 40 and the second movable core 50. The fixed core 70 has a fixed core main body 71 and a fixed core outer peripheral portion 72. The fixed core main body 71 and the fixed core outer peripheral portion 72 are formed in a cylindrical shape from a magnetic material such as ferritic stainless steel, for example.

The fixed core body 71 is formed in a substantially cylindrical shape. The fixed core outer peripheral portion 72 is formed in a substantially cylindrical shape so as to protrude radially outward from the outer wall of the fixed core main body 71. The fixed core 70 is provided coaxially with the nonmagnetic member 60 so that one end thereof is connected to the end of the nonmagnetic member 60 on the nonmagnetic protrusion 62 side. The fixed core 70 and the nonmagnetic member 60 are connected by welding, for example. Thus, the housing 20 has the nonmagnetic member 60 at the end portion on the fixed core 70 side.

More specifically, the end face on the valve seat 12 side of the fixed core outer peripheral portion 72 is located on the opposite side of the valve seat 12 with respect to the end face on the valve seat 12 side of the fixed core main body 71. The end surfaces of the nonmagnetic cylinder portion 61 and the nonmagnetic protrusion 62 on the side opposite to the valve seat 12 are in contact with the end surface of the fixed core outer peripheral portion 72 on the valve seat 12 side. The inner wall of the nonmagnetic protrusion 62 is in contact with the outer wall of the end of the fixed core body 71 on the valve seat 12 side. The end face on the valve seat 12 side of the nonmagnetic protrusion 62 is located on the valve seat 12 side with respect to the end face on the valve seat 12 side of the fixed core body 71.

A nonmagnetic contact surface 621 is formed on the end surface of the nonmagnetic protrusion 62 on the valve seat 12 side. The nonmagnetic contact surface 621 is located on the end surface of the first movable core 40 opposite to the bottom 42 of the cylindrical portion 41, that is, on the first movable core end surface 401 that is the end surface of the first movable core 40 on the fixed core 70 side. Abutment is possible. Here, the nonmagnetic contact surface 621 corresponds to a “contact surface”.

The end surface of the second movable core 50 opposite to the valve seat 12 of the movable core body 51, that is, the second movable core end surface 501, which is the end surface of the second movable core 50 on the fixed core 70 side, is The end face on the valve seat 12 side, that is, the fixed core end face 701 that is the end face on the first movable core 40 side and the second movable core 50 side of the fixed core 70 can be contacted.

An adjusting pipe 90 is provided inside the fixed core body 71. The adjusting pipe 90 is formed in a substantially cylindrical shape with, for example, metal. The adjusting pipe 90 is provided so as not to move relative to the fixed core body 71 so that the outer wall is fitted to the inner wall of the fixed core body 71. The adjusting pipe 90 is provided inside the fixed core main body 71 by, for example, press fitting.

The spring 91 is, for example, a coil spring, and is provided between the end surface of the needle 30 opposite to the valve seat 12 and the end surface of the adjusting pipe 90 on the valve seat 12 side. The spring 91 biases the needle 30 toward the valve seat 12 side. The urging force of the spring 91 can be adjusted by adjusting the position of the adjusting pipe 90 with respect to the fixed core body 71.

A spring seat 36 is provided on the valve seat 12 side with respect to the collar portion 32 of the needle body 31. The spring seat 36 is formed in a substantially annular shape from a nonmagnetic material such as austenitic stainless steel. The spring seat 36 is provided so that the inner edge portion fits to the outer wall of the needle body 31. The spring seat 36 and the needle body 31 are joined by welding, for example. As a result, the spring seat 36 is not movable relative to the needle body 31. The spring seat 36 is provided on the flange 32 side with respect to the radial hole 35.

The spring 92 is a coil spring, for example, and is provided between the recess 43 of the bottom 42 of the first movable core 40 and the spring seat 36. One end of the spring 92 is in contact with the insertion hole 44 of the recess 43 and the communication hole 45, and the other end is in contact with the spring seat 36. The spring 92 biases the first movable core 40 toward the fixed core 70 side. As a result, the outer portion of the insertion hole 44 of the surface 421 on the fixed core 70 side of the bottom 42 of the first movable core 40 is pressed against the end face of the flange 32 of the needle 30 on the valve seat 12 side. In the present embodiment, the urging force of the spring 91 is set larger than the urging force of the spring 92.

The coil 80 is formed in a substantially cylindrical shape by winding a winding such as copper. The coil 80 is provided so as to be positioned on the radially outer side of the non-magnetic member 60, the non-magnetic member 60, and the fixed core outer peripheral portion 72 of the second cylindrical portion 22 of the housing 20.

In this embodiment, a yoke 81 is further provided. The yoke 81 is formed in a cylindrical shape from a magnetic material such as ferritic stainless steel. The yoke 81 is provided so as to cover the outer wall and both ends of the coil 80. One end of the yoke 81 is connected to the outer wall of the second cylindrical portion 22 of the housing 20, and the other end is connected to the outer wall of the fixed core outer peripheral portion 72 of the fixed core 70.

The coil 80 generates a magnetic flux when energized. When magnetic flux is generated in the coil 80, magnetic flux flows through the fixed core 70, the yoke 81, the second cylindrical portion 22, the first movable core 40, and the second movable core 50 so as to avoid the nonmagnetic member 60, thereby forming a magnetic circuit. Is done. Thereby, the 1st movable core 40 and the 2nd movable core 50 are attracted | sucked to the fixed core 70 side. At this time, the first movable core 40 is sucked toward the fixed core 70 in a state where the bottom portion 42 is in contact with the flange portion 32. As a result, the needle 30 moves in the valve opening direction and opens.

An inlet 101 is formed on the opposite side of the fixed core body 71 from the valve seat 12. The fuel that has flowed into the inside of the fixed core body 71 via the inflow port 101 flows through the inside of the adjusting pipe 90, the axial hole portion 34, the radial hole portion 35, and the inside of the first tube portion 21 of the housing 20. And guided to the nozzle hole 11. The fuel flowing in from the inlet 101 fills the inside of the housing 20, the inside of the nonmagnetic member 60, the inside of the fixed core 70, that is, the fuel passage 100. In this embodiment, relatively high-pressure fuel flows from the inlet 101 when the fuel injection device 1 is operated. Therefore, the fuel pressure in the fuel passage 100 is relatively high.

As shown in FIG. 1, when the coil 80 is not energized, the needle 30 is biased toward the valve seat 12 by the biasing force of the spring 91, and the seal portion 33 contacts the valve seat 12 to close the valve. ing. Further, the first movable core 40 is biased toward the fixed core 70 by the biasing force of the spring 92, and the bottom portion 42 is in contact with the flange portion 32 of the needle 30. In this state, the distance g1 between the first movable core end surface 401 that is the end surface of the first movable core 40 on the fixed core 70 side and the fixed core end surface 701 that is the end surface of the fixed core 70 on the first movable core 40 side is The distance between the second movable core end surface 501 and the fixed core end surface 701 which is the end surface of the two movable cores 50 on the fixed core 70 side is set smaller. The distance g3 between the first movable core end surface 401 and the nonmagnetic contact surface 621 at this time is equal to the distance g1 minus the distance d1 between the fixed core end surface 701 and the nonmagnetic contact surface 621. . Further, the maximum lift amount of the needle 30 is equal to the distance g2.

Next, the operation of the fuel injection device 1 of the present embodiment will be described in detail based on FIGS. As shown in FIG. 1, when the coil 80 is not energized, the needle 30 is closed. As shown in FIG. 2, when the inside of the fuel passage 100 is filled with fuel, the fuel pressure Ff acts on the end surface of the needle 30 opposite to the valve seat 12. When the coil 80 is energized, magnetic flux is generated, and a magnetic circuit is formed in the fixed core 70, the yoke 81, the second cylindrical portion 22, the first movable core 40, and the second movable core 50. Thereby, a suction force is generated between the first movable core 40 and the second movable core 50 and the fixed core 70, and the first movable core 40 and the second movable core 50 are sucked to the fixed core 70 side. As a result, the needle 30 moves in the valve opening direction against the urging force of the spring 91 and the fuel pressure Ff, and the seal portion 33 is separated from the valve seat 12 and opened. As a result, fuel injection from the nozzle hole 11 is started.

In the present embodiment, since the annular movable core gap s1 is formed between the first movable core 40 and the second movable core 50, the gap between the first movable core 40 and the second movable core 50 is determined. The magnetic resistance is large. Further, in the initial energization of the coil 80 shown in FIG. 2, that is, in the state where the needle 30 is closed, the distance g1 between the fixed core end surface 701 and the first movable core end surface 401 is equal to the fixed core end surface 701 and the second core end surface 701. The distance from the movable core end surface 501 is smaller than g2. Therefore, the magnetic flux does not flow so much through the second movable core 50 but flows through the first movable core 40. As a result, the suction force between the first movable core 40 and the second movable core 50, particularly the first movable core 40 and the fixed core 70, can be increased. Therefore, when the fuel pressure in the fuel passage 100 is relatively high, the needle 30 can be opened even if the amount of current supplied to the coil 80 is relatively small.

When energization of the coil 80 is continued and the first movable core 40, the second movable core 50, and the needle 30 further move in the valve opening direction, the first movable core end surface 401 of the first movable core 40 is brought into nonmagnetic contact. It abuts on the surface 621 (see FIG. 3). Thereby, the movement in the valve opening direction of the 1st movable core 40 is controlled. When the first movable core 40 is in contact with the nonmagnetic contact surface 621, a substantially annular inter-core gap s2 is formed between the first movable core end surface 401 and the fixed core end surface 701. That is, in a state where the first movable core 40 is in contact with the nonmagnetic contact surface 621, the first movable core end surface 401 and the fixed core end surface 701 are separated from each other.

At this time, the distance between the fixed core end surface 701 and the second movable core end surface 501 is smaller than the initial energization of the coil 80 (see FIG. 2). Therefore, a large amount of magnetic flux also flows through the second movable core 50, and the attractive force between the fixed core 70 and the second movable core 50 increases. At this time, since the needle 30 is opened, the fuel pressure Ff acts on the outer edge portion of the end surface of the needle body 31 on the valve seat 12 side, that is, the seal portion 33. Therefore, the fuel pressure Ff is applied to both ends of the needle 30. When the fuel pressure in the fuel passage 100 is relatively high, the needle 30 opens in the valve opening direction even if the amount of current supplied to the coil 80 is relatively small. Can be moved further.

When energization of the coil 80 is continued and the second movable core 50 and the needle 30 further move in the valve opening direction, the second movable core end surface 501 of the second movable core 50 comes into contact with the fixed core end surface 701 (FIG. 4). reference). Thereby, the 2nd movable core 50 and the needle 30 are controlled to move in the valve opening direction. In the present embodiment, when the second movable core end surface 501 contacts the fixed core end surface 701, the lift amount of the needle 30 is maximized.

When the state shown in FIG. 3 is shifted to the state shown in FIG. 4, the second movable core 50 has the end surface 512 on the valve seat 12 side of the movable core body 51, and the fixed core of the bottom portion 42 of the first movable core 40. It moves in the valve opening direction, which is the direction away from the 70-side surface 421. In this embodiment, the gap s1 between the movable cores is formed between the surface 421 on the fixed core 70 side of the bottom 42 of the first movable core 40 and the entire end surface 512 on the valve seat 12 side of the movable core body 51 of the second movable core 50. In this case, the ringing force generated between the end surface 512 of the movable core body 51 on the valve seat 12 side and the surface 421 of the bottom 42 on the fixed core 70 side can be reduced. In the present embodiment, since the communication hole 45 communicates with the movable core gap s1, at this time, part of the fuel in the communication hole 45 flows into the movable core gap s1. Therefore, the second movable core 50 is easy to move in the valve opening direction that is the direction away from the first movable core 40. Therefore, the needle 30 can be quickly moved in the valve opening direction.

When the power supply to the coil 80 is stopped in the state shown in FIG. 4, the attractive force between the fixed core 70, the first movable core 40, and the second movable core 50 disappears. Thereby, the needle 30 and the second movable core 50 are moved in the valve closing direction by the biasing force of the spring 91. As a result, the end surface of the flange portion 32 on the valve seat 12 side contacts the surface 421 on the fixed core 70 side of the bottom portion 42 of the first movable core 40 (see FIG. 5).

When the state shown in FIG. 4 is shifted to the state shown in FIG. 5, the second movable core 50 has the end surface 512 on the valve seat 12 side of the movable core body 51, and the fixed core of the bottom portion 42 of the first movable core 40. It moves in the valve closing direction so as to approach the surface 421 on the 70 side. In the present embodiment, since the communication hole 45 communicates with the movable core gap s 1, at this time, part of the fuel in the movable core gap s 1 flows into the communication hole 45. Therefore, the second movable core 50 and the needle 30 are easy to move in the valve closing direction. Therefore, the needle 30 can be quickly moved in the valve closing direction.

When the needle 30 further moves in the valve closing direction with the collar portion 32 in contact with the first movable core 40, the first movable core end surface 401 is separated from the nonmagnetic contact surface 621, and the seal portion 33 is moved to the valve seat 12. The needle 30 closes (see FIG. 6). Thereby, the fuel injection from the nozzle hole 11 is stopped.

In addition, when shifting from the state shown in FIG. 5 to the state shown in FIG. 6, the first movable core 40 moves in the valve closing direction in which the first movable core end surface 401 is away from the fixed core end surface 701. In the present embodiment, the inter-core gap s2 is formed between the first movable core end surface 401 and the fixed core end surface 701 in a state where the first movable core end surface 401 is in contact with the nonmagnetic contact surface 621. The first movable core 40 is easy to move in the valve closing direction, which is the direction away from the fixed core 70. Therefore, the needle 30 can be quickly moved in the valve closing direction.

After the state shown in FIG. 6, the first movable core 40 further moves in the valve closing direction due to inertia (see FIG. 7). When the state shown in FIG. 6 is shifted to the state shown in FIG. 7, the first movable core 40 has a surface 421 on the fixed core 70 side of the bottom 42, and the valve core 12 side of the movable core body 51 of the second movable core 50. It moves in the valve closing direction, which is the direction away from the end face 512 of the valve. In this embodiment, the gap s1 between the movable cores is formed between the surface 421 on the fixed core 70 side of the bottom 42 of the first movable core 40 and the entire end surface 512 on the valve seat 12 side of the movable core body 51 of the second movable core 50. In this case, the ringing force generated between the end surface 512 of the movable core body 51 on the valve seat 12 side and the surface 421 of the bottom 42 on the fixed core 70 side can be reduced. In the present embodiment, since the communication hole 45 communicates with the movable core gap s1, at this time, part of the fuel in the communication hole 45 flows into the movable core gap s1. Therefore, the first movable core 40 easily moves in the valve closing direction, which is the direction away from the second movable core 50. Therefore, the collision energy when the seal portion 33 of the needle 30 contacts the valve seat 12 (see FIG. 6) can be reduced. Therefore, it is possible to suppress the needle 30 from bouncing at the valve seat 12 and to suppress an unintended secondary valve opening.

After the state shown in FIG. 7, the first movable core 40 moves in the valve opening direction by the biasing force of the spring 92. As a result, in the first movable core 40, the surface 421 of the bottom 42 on the fixed core 70 side comes into contact with the end surface of the flange 32 on the valve seat 12 side, and movement in the valve opening direction is restricted (see FIG. 1).

In addition, when shifting from the state shown in FIG. 7 to the state shown in FIG. 1, a part of the fuel in the gap s1 between the movable cores flows into the communication hole 45. Therefore, a so-called damper effect is generated in the first movable core 40, and the collision energy when the first movable core 40 abuts against the flange portion 32 can be reduced. Thereby, the unintended valve opening by the 1st movable core 40 colliding with the collar part 32 can be suppressed. As described above, the fuel injection device 1 repeats the states shown in FIGS. 1 to 7 when continuing to inject fuel into the engine.

As described above, (1) the fuel injection device 1 according to the present embodiment includes the nozzle 10, the housing 20, the needle 30, the first movable core 40, the second movable core 50, the fixed core 70, and the coil 80. Yes. The nozzle 10 has a nozzle hole 11 through which fuel is injected, and a valve seat 12 formed around the nozzle hole 11. The housing 20 is formed in a cylindrical shape, has one end connected to the nozzle 10, and has a fuel passage 100 that is formed inside so as to communicate with the injection hole 11 and guides fuel to the injection hole 11. The needle 30 is provided so as to be capable of reciprocating inside the housing 20, and opens when one end is separated from the valve seat 12, and closes when one end contacts the valve seat 12. The first movable core 40 is provided to be movable relative to the needle 30. The second movable core 50 is provided so as not to move relative to the needle 30. The fixed core 70 is provided on the opposite side of the valve seat 12 with respect to the first movable core 40 and the second movable core 50. The coil 80 generates magnetic flux when energized, and can attract the first movable core 40 and the second movable core 50 toward the fixed core 70 and move the needle 30 to the side opposite to the valve seat 12.

In the present embodiment, of the first movable core 40 and the second movable core 50, the surface 421 on the fixed core 70 side of the bottom 42 of the first movable core 40 and the movable core body 51 of the second movable core 50. An annular movable inter-core gap s1 is formed between the end face 512 on the valve seat 12 side. Therefore, the magnetic resistance between the first movable core 40 and the second movable core 50 can be increased. Thereby, when the coil 80 is energized, a large amount of magnetic flux can flow through the first movable core 40 of the first movable core 40 and the second movable core 50, and the first movable core 40 and the fixed core 70 The suction force between the two can be increased. Therefore, even when the fuel pressure in the fuel passage 100 is high, the needle 30 can be opened. Therefore, in this embodiment, high-pressure fuel can be injected.

In the present embodiment, since the annular movable core gap s1 is formed between the first movable core 40 and the second movable core 50, the first movable core 40 and the second movable core 50 are separated from each other. The ringing force generated when trying to do so can be reduced. Therefore, it is possible to suppress a decrease in the valve opening speed of the needle and an unintended secondary valve opening that may occur in the conventional fuel injection device. Therefore, in this embodiment, fuel can be injected with high accuracy.

(2) In the present embodiment, the nonmagnetic member 60 of the housing 20 is the first movable core 40 and the first movable core 50, which is the surface of the first movable core 40 on the fixed core 70 side. A nonmagnetic contact surface 621 that can contact the core end surface 401 is provided. When the first movable core end surface 401 and the nonmagnetic contact surface 621 contact each other, an annular inter-core gap s <b> 2 is formed between the first movable core 40 and the fixed core 70. Therefore, when energization of the coil 80 is stopped and the needle 30 is closed, the residual magnetism of the fixed core 70 affects the first movable core 40 or between the fixed core 70 and the first movable core 40. It is possible to suppress the occurrence of ringing force. Thereby, it can suppress that the 1st movable core 40 will be in the state which contact | abutted to the fixed core 70. FIG. Therefore, the needle 30 can be quickly closed after energization of the coil 80 is stopped. Therefore, in this embodiment, fuel can be injected with high accuracy.

(4) In the present embodiment, the housing 20 has a nonmagnetic member 60 formed of a nonmagnetic material at the end on the fixed core 70 side. The nonmagnetic contact surface 621 is formed on the end surface of the nonmagnetic member 60 on the valve seat 12 side. Therefore, when the energization to the coil 80 is stopped while the first movable core end surface 401 is in contact with the nonmagnetic contact surface 621, the first movable core 40 is quickly separated from the nonmagnetic contact surface 621. Thereby, the responsiveness of the fuel injection device 1 can be improved.

(9) In the present embodiment, the first movable core 40 has a communication hole 45 communicating with the gap s1 between the movable cores. Therefore, the fuel can be moved back and forth between the movable core gap s 1 and the communication hole 45. Accordingly, when the needle 30 is opened and closed, the first movable core 40 and the second movable core 50 can be quickly separated from each other, or the collision energy when the needle 30 comes into contact with another member can be reduced. . Therefore, the fuel can be injected with high accuracy.

(10) In the present embodiment, when the first movable core 40 abuts a part (32) of the needle 30, a gap s1 between the movable cores is formed between the first movable core 40 and the second movable core 50. In the present embodiment, since the needle 30 is made of a nonmagnetic material, the magnetic resistance between the first movable core 40 and the second movable core 50 can be increased. Thereby, the suction force between the first movable core 40 and the fixed core 70 can be made larger than the suction force between the second movable core 50 and the fixed core 70.

(11) In this embodiment, the needle 30 has a rod-shaped needle body 31 and a flange 32 provided on the radially outer side of the needle body 31. When the first movable core 40 comes into contact with the flange portion 32, a gap s1 between the movable cores is formed between the first movable core 40 and the second movable core 50. This exemplifies a specific configuration of the present disclosure.

(14) When the needle 30 is in contact with the valve seat 12, the first movable core end surface 401, which is the end surface of the first movable core 40 on the fixed core 70 side, the first movable core 40 of the fixed core 70, and The distance from the fixed core end surface 701 that is the end surface on the second movable core 50 side is set to be smaller than the distance between the second movable core end surface 501 that is the end surface on the fixed core 70 side of the second movable core 50 and the fixed core end surface 701. Has been. Therefore, at the initial stage of energization of the coil 80, the attractive force between the first movable core 40 and the fixed core 70 can be made larger than the attractive force between the second movable core 50 and the fixed core 70. Thereby, even when the fuel pressure in the fuel passage 100 is high, the needle 30 can be opened.

(15) The present embodiment further includes a spring 91 and a spring 92. The spring 91 biases the needle 30 toward the valve seat 12 side. The spring 92 biases the first movable core 40 of the first movable core 40 and the second movable core 50 toward the fixed core 70. This exemplifies a specific configuration of the present disclosure.

(Second Embodiment)
A fuel injection device according to the second embodiment is shown in FIGS. The second embodiment is different from the first embodiment in the configuration of the nonmagnetic member 60 and the fixed core 70.

As shown in FIG. 8, in the second embodiment, the nonmagnetic member 60 does not have the nonmagnetic protrusion 62 shown in the first embodiment, and consists only of the nonmagnetic cylinder 61. In the nonmagnetic member 60, the inner wall of the end portion of the nonmagnetic cylinder portion 61 opposite to the valve seat 12 is in contact with the outer wall of the end portion of the fixed core body 71 on the valve seat 12 side.

The fixed core 70 further has a fixed core protrusion 73. The fixed core protrusion 73 is formed so as to protrude from the outer edge of the fixed core end surface 701 to the valve seat 12 side in a substantially annular shape. A fixed core contact surface 731 is formed on the end surface of the fixed core protrusion 73 on the valve seat 12 side. The fixed core contact surface 731 can contact the first movable core end surface 401 of the first movable core 40 (see FIG. 9). Here, the fixed core contact surface 731 corresponds to a “contact surface”. Further, the protruding height of the fixed core protrusion 73 from the fixed core end surface 701, that is, the distance d1 between the fixed core end surface 701 and the fixed core abutting surface 731 is different from the fixed core end surface 701 shown in the first embodiment. The distance d1 is the same as the distance d1 from the magnetic contact surface 621.

As shown in FIG. 9, when the first movable core 40 abuts on the fixed core abutment surface 731, a substantially annular inter-core gap s <b> 2 is formed between the first movable core end surface 401 and the fixed core end surface 701. Form. That is, in a state where the first movable core 40 is in contact with the fixed core contact surface 731, the first movable core end surface 401 and the fixed core end surface 701 are separated from each other. The second embodiment is the same as the first embodiment except for the points described above.

As described above, (2) in the present embodiment, the fixed core protrusion 73 of the fixed core 70 is located on the fixed core 70 side of the first movable core 40 of the first movable core 40 and the second movable core 50. It has a fixed core contact surface 731 that can contact the first movable core end surface 401 that is a surface. When the first movable core end surface 401 and the fixed core contact surface 731 come into contact with each other, an annular inter-core gap s <b> 2 is formed between the first movable core 40 and the fixed core 70. Therefore, as in the first embodiment, when the energization to the coil 80 is stopped and the needle 30 is closed, the influence of the residual magnetism of the fixed core 70 affects the first movable core 40 or the fixed core 70 and the first core. Generation of ringing force between the movable core 40 and the movable core 40 can be suppressed. Thereby, it can suppress that the 1st movable core 40 will be in the state which contact | abutted to the fixed core 70. FIG. Therefore, the needle 30 can be quickly closed after energization of the coil 80 is stopped. Therefore, in this embodiment, fuel can be injected with high accuracy.

Further, (5) the fixed core 70 is formed with a fixed core abutting surface 731 which is a surface capable of abutting on the first movable core end surface 401 which is an end surface of the first movable core 40 on the fixed core 70 side. . (6) In the present embodiment, the fixed core 70 includes a cylindrical fixed core main body 71 and a fixed core end surface 701 that is an end surface of the fixed core main body 71 on the first movable core 40 side and the second movable core 50 side. The fixed core protrusion 73 protrudes from the first movable core 40 to the first movable core 40 side. The fixed core contact surface 731 is formed on the end surface of the fixed core protrusion 73 on the first movable core 40 side. This exemplifies a specific configuration of the present disclosure.

(Third embodiment)
A fuel injection device according to a third embodiment is shown in FIGS. The third embodiment differs from the first embodiment in the configuration of the fixed core 70.

As shown in FIG. 10, in the third embodiment, the fixed core 70 further includes a bush 74. The bush 74 is formed in a substantially cylindrical shape by a nonmagnetic material such as austenitic stainless steel. The bush 74 is provided inside the end of the fixed core body 71 on the valve seat 12 side. The outer wall of the bush 74 is fitted to the inner wall of the fixed core body 71. The bush 74 is fixed to the fixed core body 71 by welding, for example. Here, the end surface of the bush 74 on the valve seat 12 side is located on the valve seat 12 side with respect to the fixed core end surface 701.

A fixed core contact surface 741 is formed on the end surface of the bush 74 on the valve seat 12 side. The fixed core abutting surface 741 can abut on the second movable core end surface 501 of the second movable core 50 and the end surface of the flange portion 32 opposite to the valve seat 12 (see FIG. 11). Here, the fixed core contact surface 741 corresponds to a “contact surface”. The distance d2 between the fixed core contact surface 741 and the fixed core end surface 701 is smaller than the distance d1 between the nonmagnetic contact surface 621 and the fixed core end surface 701.

As shown in FIG. 11, when the second movable core 50 abuts against the fixed core abutment surface 741, a substantially annular inter-core gap s 3 is provided between the second movable core end surface 501 and the fixed core end surface 701. Form. That is, in a state where the second movable core 50 is in contact with the fixed core contact surface 741, the second movable core end surface 501 and the fixed core end surface 701 are separated from each other. The third embodiment is the same as the first embodiment except for the points described above.

As described above, (2) in this embodiment, the bush 74 of the fixed core 70 is the surface of the first movable core 40 and the second movable core 50 on the fixed core 70 side of the second movable core 50. The second movable core end surface 501 and the fixed core contact surface 741 that can contact the surface of the needle 30 on the fixed core 70 side are provided. When the second movable core end surface 501 and the needle 30 are in contact with the fixed core contact surface 741, an annular inter-core gap s 3 is formed between the second movable core 50 and the fixed core 70. Therefore, when energization of the coil 80 is stopped and the needle 30 is closed, the residual magnetism of the fixed core 70 affects the second movable core 50 or between the fixed core 70 and the second movable core 50. It is possible to suppress the occurrence of ringing force. Thereby, it can suppress that the 2nd movable core 50 will be in the state which contact | abutted to the fixed core 70. FIG. Therefore, the needle 30 can be quickly closed after energization of the coil 80 is stopped. Therefore, in this embodiment, fuel can be injected with high accuracy.

Further, (5) the fixed core 70 is a surface that can abut on the second movable core end surface 501 that is the end surface of the second movable core 50 on the fixed core 70 side and the end surface of the needle 30 opposite to the valve seat 12. A fixed core contact surface 741 is formed. (7) In the present embodiment, the fixed core 70 has a cylindrical fixed core main body 71 and a cylindrical bush 74 provided inside the fixed core main body 71. The fixed core contact surface 741 is formed on the end surface of the bush 74 on the second movable core 50 side. This exemplifies a specific configuration of the present disclosure.

(Fourth embodiment)
FIG. 12 shows a fuel injection device according to the fourth embodiment. The fourth embodiment differs from the first embodiment in the configuration of the needle 30 and the second movable core 50. In 4th Embodiment, the needle 30 does not have the collar part 32 shown in 1st Embodiment.

The second movable core 50 has a movable core body 51 and a movable core protrusion 52. The movable core body 51 is provided so that the inner wall is fitted to the outer wall of the end portion of the needle body 31 opposite to the seal portion 33. In the present embodiment, the movable core body 51 is fixed to the needle body 31 by, for example, press fitting or welding. That is, the second movable core 50 is provided so as not to move relative to the needle 30.

The movable core projecting portion 52 is formed so as to project in a substantially annular shape from the inner edge portion of the end surface 512 of the movable core body 51 on the valve seat 12 side to the valve seat 12 side. Therefore, the end surface on the valve seat 12 side of the movable core projecting portion 52 is located on the valve seat 12 side with respect to the end surface 512 on the valve seat 12 side of the movable core body 51 of the second movable core 50. Between the surface 421 of the bottom 42 of the first movable core 40 on the fixed core 70 side and the end surface 512 of the movable core body 51 of the second movable core 50 on the valve seat 12 side, there is a substantially annular gap s1 between the movable cores. Is formed. The axial size of the gap s1 between the movable cores varies depending on the position of the first movable core 40 with respect to the needle body 31, and the bottom 42 of the first movable core 40 is located on the end face of the movable core protrusion 52 on the valve seat 12 side. When abutting, it is minimum. Thus, regardless of whether or not the bottom 42 of the first movable core 40 is in contact with the end face of the movable core protrusion 52 on the valve seat 12 side, the surface 421 on the fixed core 70 side of the bottom 42 and the movable core main body. 51 is always separated from the end surface 512 on the valve seat 12 side, and a gap s1 between the movable cores is formed therebetween. The configuration of the fourth embodiment is the same as that of the first embodiment except for the points described above.

As described above, (10) in the present embodiment, when the first movable core 40 abuts a part (52) of the second movable core 50, the movable core is between the second movable core 50 and the movable core. A gap s1 is formed. In this embodiment, since the needle 30 does not have the collar part 32, the shape of the needle 30 can be simplified. Therefore, the processing cost of the needle 30 can be reduced. Further, the volume of the second movable core 50 can be increased by the amount that the needle 30 does not have the flange portion 32. Therefore, the suction force between the fixed core 70 and the second movable core 50 can be increased.

(12) In the present embodiment, the second movable core 50 includes the movable core main body 51 and the movable core protruding portion 52 that protrudes from the end face 512 of the movable core main body 51 on the valve seat 12 side to the valve seat 12 side. Have. When the first movable core 40 comes into contact with the movable core protrusion 52, a movable inter-core gap s1 is formed between the first movable core 40 and the end surface 512 of the movable core body 51 on the valve seat 12 side. This exemplifies a specific configuration of the present disclosure.

A modification of the above embodiment will be described. In the first, second, and fourth embodiments described above, the example in which both the movable inter-core gap s1 and the inter-core gap s2 are formed has been described. On the other hand, in the modification of the above embodiment, only one of the movable inter-core gap s1 and the inter-core gap s2 may be formed. That is, the structure which the 1st movable core end surface 401 and the fixed core end surface 701 contact | abut may be sufficient. In this case, when the first movable core end surface 401 and the fixed core end surface 701 come into contact with each other, the inter-core gap s2 is not formed. Alternatively, the surface 421 on the fixed core 70 side of the bottom 42 of the first movable core 40 and the end surface 512 on the valve seat 12 side of the movable core body 51 of the second movable core 50 may be in contact with each other. In this case, when the surface 421 on the fixed core 70 side of the bottom 42 of the first movable core 40 and the end surface 512 on the valve seat 12 side of the movable core main body 51 of the second movable core 50 abut, the gap s1 between the movable cores. Is not formed.

Further, in the above-described third embodiment, the example in which the movable inter-core gap s1, the inter-core gap s2, and the inter-core gap s3 are formed is shown. On the other hand, in the modified example of the above embodiment, at least one of the movable inter-core gap s1, the inter-core gap s2, and the inter-core gap s3 may be formed.

In the modification of the above embodiment, the bush 74 may be configured to contact only the surface of the needle 30 on the fixed core 70 side without contacting the second movable core 50. In the case of this configuration, wear of the second movable core 50 due to contact with the bush 74 can be prevented.

In the above-described embodiment, the configuration in which the outer wall of the movable core body 51 of the second movable core 50 is slidable with the inner wall of the cylindrical portion 41 of the first movable core 40 is exemplified. On the other hand, in the modified example of the above embodiment, for example, the inner diameter of the insertion hole 44 of the bottom 42 of the first movable core 40 is set slightly larger than the outer diameter of the needle body 31, and the outer diameter of the movable core body 51 is set to be a cylinder. By setting it smaller than the inner diameter of the portion 41, a cylindrical clearance may always be formed between the outer wall of the movable core body 51 and the inner wall of the cylindrical portion 41. In this configuration, the magnetic resistance between the first movable core 40 and the second movable core 50 can be increased, and the attractive force between the first movable core 40 and the fixed core 70 can be increased. In addition, since the cylindrical clearance is always in communication with the movable core gap s1, fuel can be transferred between the movable core gap s1 and the cylindrical clearance. Accordingly, when the needle 30 is opened and closed, the first movable core 40 and the second movable core 50 can be quickly separated from each other, or the collision energy when the needle 30 comes into contact with another member can be reduced. . Therefore, the fuel can be injected with high accuracy. In this configuration, the communication hole 45 may be omitted. In the modification of the above embodiment, the communication hole 45 may be formed in the second movable core 50.

In the above-described embodiment, when the needle 30 is in contact with the valve seat 12, the distance g1 between the first movable core end surface 401 of the first movable core 40 and the fixed core end surface 701 of the fixed core 70 is The example in which the distance between the second movable core end surface 501 and the fixed core end surface 701 of the two movable cores 50 is set smaller than the distance g2 is shown. On the other hand, in the modified example of the above embodiment, the distance g1 may be set to the distance g2 or more.

In the above-described embodiment, the example in which the spring 92 as the second urging member is provided between the first movable core 40 and the spring seat 36 has been described. On the other hand, in the modified example of the above embodiment, the spring seat 36 is omitted, and the spring 92 has one end in contact with the first movable core 40 and the other end in contact with the stepped surface 201 of the housing 20. The core 40 may be provided to be urged in the valve opening direction.

Further, in the above-described third embodiment, the example in which the bush 74 is formed separately from the fixed core main body 71 is shown. On the other hand, in the modified example of the above embodiment, the bush 74 may be formed integrally with the fixed core body 71. In addition, the distance d2 between the fixed core contact surface 741 that is the end surface of the bush 74 on the valve seat 12 side and the fixed core end surface 701 that is the end surface of the fixed core body 71 on the valve seat 12 side is any size. May be. However, when the nonmagnetic contact surface 621 is formed on the nonmagnetic member 60, or when the fixed core contact surface 731 is formed on the fixed core 70, the distance d2 is the nonmagnetic contact surface 621 or fixed. What is necessary is just to set smaller than the distance d1 of the core contact surface 731 and the fixed core end surface 701. Moreover, in the modification of the said embodiment, the housing 20 is replaced with the nonmagnetic member 60, and has a magnetic aperture part which is formed in a cylindrical shape from a magnetic material and has a partly axial thickness smaller than that of other parts. It is good. In this case, a contact surface that can be in contact with the first movable core end surface 401 may be formed in the magnetic aperture portion, similar to the nonmagnetic contact surface 621.

Further, in the above-described embodiment, an example in which the two movable cores of the first movable core 40 and the second movable core 50 are provided is shown. On the other hand, the modification of the said embodiment may be provided with three or more movable cores. For example, the movable core main body 51 of the second movable core 50 is divided into two in the axial direction, the divided body on the fixed core 70 side is provided so as not to move relative to the needle 30, and the divided body on the valve seat 12 side is provided with the needle 30. For example, it is provided so as to be relatively movable.

In the above-described embodiment, an example in which the nozzle 10 is formed integrally with the housing 20 has been described. On the other hand, in the modified example of the above embodiment, the nozzle 10 may be formed separately from the housing 20. In this case, for example, if the nozzle 10 is formed of the same material as that of the needle 30, wear of the valve seat 12 of the nozzle 10 associated with the opening / closing valve of the needle 30 can be suppressed.

In the above-described embodiment, the example in which the fixed core outer peripheral portion 72 is formed integrally with the fixed core main body 71 is shown. On the other hand, in the modified example of the above embodiment, the fixed core outer peripheral portion 72 may be formed separately from the fixed core main body 71.

In the modification of the above embodiment, the cylindrical flange 32, the nonmagnetic protrusion 62, and the bush 74 may be formed in a shape with a part of the circumferential direction missing. Moreover, in the modification of the said embodiment, the cyclic | annular fixed core protrusion part 73 and the movable core protrusion part 52 may be formed in the shape where a part of circumferential direction lacked.

Moreover, in the modification of the said embodiment, the housing 20, the 1st movable core 40, the 2nd movable core 50, the fixed core 70, and the yoke 81 may be formed not only with ferritic stainless steel but with another magnetic material. Good. Further, the needle 30, the nonmagnetic member 60, the spring seat 36, and the bush 74 are not limited to austenitic stainless steel, and may be formed of other nonmagnetic materials. The needle 30 may be made of martensitic stainless steel, for example. The present disclosure is not limited to injecting high-pressure fuel, and may be used to inject low-pressure fuel. Further, the present disclosure is not limited to a direct injection type gasoline engine, and may be applied to, for example, a port injection type gasoline engine or a diesel engine. Thus, the present disclosure is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist thereof.

Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims

A nozzle (10) having a nozzle hole (11) through which fuel is injected, and a valve seat (12) formed around the nozzle hole;
A cylindrical housing (20) having one end connected to the nozzle and having a fuel passage (100) formed inside to communicate with the nozzle hole and guiding fuel to the nozzle hole;
A needle (30) which is provided inside the housing so as to be reciprocally movable and opens when one end is separated from the valve seat and closes when one end contacts the valve seat;
A plurality of movable cores (40, 50) provided so as to be movable relative to the needle or not movable relative to the needle;
A fixed core (70) provided on the opposite side of the valve seat to the movable core;
A coil (80) capable of generating magnetic flux when energized, attracting the movable core toward the fixed core, and moving the needle to the opposite side of the valve seat;
Of the plurality of movable cores, one of the movable cores (40) on the fixed core side surface (421) and the other movable core (50) different from the one movable core on the valve seat side. A fuel injection device (1) in which an annular gap (s1) between movable cores is formed between the surface (512).
The housing or the fixed core is capable of abutting against a surface (401, 501) of the movable core of at least one of the movable cores or a surface of the needle on the side of the fixed core. Have contact surfaces (621, 731, 741),
When the surface of the movable core on the side of the fixed core or the surface of the needle on the side of the fixed core is in contact with the contact surface, an annular inter-core gap (s2) is formed between the movable core and the fixed core. , S3).
A nozzle (10) having a nozzle hole (11) through which fuel is injected, and a valve seat (12) formed around the nozzle hole;
A cylindrical housing (20) having one end connected to the nozzle and having a fuel passage (100) formed inside to communicate with the nozzle hole and guiding fuel to the nozzle hole;
A needle (30) which is provided inside the housing so as to be reciprocally movable and opens when one end is separated from the valve seat and closes when one end contacts the valve seat;
A plurality of movable cores (40, 50) provided so as to be movable relative to the needle or not movable relative to the needle;
A fixed core (70) provided on the opposite side of the valve seat to the movable core;
A coil (80) capable of generating magnetic flux when energized, attracting the movable core toward the fixed core, and moving the needle to the opposite side of the valve seat;
The housing or the fixed core is capable of abutting against a surface (401, 501) of the movable core of at least one of the movable cores or a surface of the needle on the side of the fixed core. Have contact surfaces (621, 731, 741),
When the surface of the movable core on the side of the fixed core or the surface of the needle on the side of the fixed core is in contact with the contact surface, an annular inter-core gap (s2) is formed between the movable core and the fixed core. , S3), a fuel injection device (1).
The housing has a nonmagnetic member (60) formed of a nonmagnetic material at an end on the fixed core side,
The fuel injection device according to claim 2 or 3, wherein the contact surface includes a nonmagnetic contact surface (621) formed on a surface of the nonmagnetic member on the valve seat side.
The fuel injection device according to any one of claims 2 to 4, wherein the contact surface includes a fixed core contact surface (731, 741) formed on the fixed core.
The fixed core has a cylindrical fixed core body (71), and a fixed core protrusion (73) protruding from the surface (701) of the fixed core body on the movable core side toward the movable core,
The fuel injection device according to claim 5, wherein the fixed core abutting surface (731) is formed on a surface of the fixed core protruding portion on the movable core side.
The fixed core has a cylindrical fixed core body (71) and a cylindrical bush (74) provided inside the fixed core body,
The fuel injection device according to claim 5, wherein the fixed core contact surface (741) is formed on a surface of the bush on the movable core side.
Of the plurality of movable cores, one of the movable cores (40) on the fixed core side surface (421) and the other movable core (50) different from the one movable core on the valve seat side. The fuel injection device according to any one of claims 3 to 7, wherein an annular gap (s1) between the movable cores is formed between the surface (512).
The fuel injection device according to claim 1, 2 or 8, wherein the movable core has a communication hole (45) communicating with the gap between the movable cores.
The plurality of movable cores include a first movable core (40) provided so as to be relatively movable with respect to the needle, and a second movable core (50) provided so as not to be relatively movable with respect to the needle,
The first movable core forms a gap between the movable cores between the first movable core and the second movable core when the first movable core comes into contact with a part (32) of the needle or a part (52) of the second movable core. The fuel injection device according to claim 1, 2, 8 or 9.
The needle has a rod-shaped needle body (31) and a flange (32) provided on the radially outer side of the needle body,
11. The fuel injection device according to claim 10, wherein the first movable core forms a gap between the movable cores with the second movable core when the first movable core comes into contact with the flange portion.
The second movable core has a movable core main body (51) and a movable core projecting portion (52) projecting from the valve seat side end surface of the movable core main body to the valve seat side,
11. The fuel injection device according to claim 10, wherein when the first movable core abuts on the movable core projecting portion, the gap between the movable cores is formed between the first movable core and an end face on the valve seat side of the movable core body. .
The plurality of movable cores include a first movable core (40) provided to be movable relative to the needle and a second movable core (50) provided to be non-movable relative to the needle. 10. The fuel injection device according to any one of 1 to 9.
When the needle is in contact with the valve seat, the first movable core end surface (401) which is the end surface on the fixed core side of the first movable core and the fixed surface which is the end surface on the movable core side of the fixed core. The distance (g1) from the core end surface (701) is set to be smaller than the distance (g2) between the second movable core end surface (501), which is the end surface on the fixed core side of the second movable core, and the fixed core end surface. The fuel injection device according to any one of claims 10 to 13.
A first biasing member (91) for biasing the needle toward the valve seat;
A second biasing member (92) for biasing at least one of the plurality of movable cores toward the fixed core;
The fuel injection device according to any one of claims 1 to 14, further comprising: