Fuel injector

Abstract

A fuel injector comprises a coil (70), a solid core (50), a movable core (40), a valve body (30), an inner core part (52) that is part of the solid core which faces the movable core, an outer core part (51) that is part of the solid core which faces the movable core and is located outside the inner core part with respect to the annular center line (C), a non-magnetic component (60) that is arranged between the inner core part and the outer core part and has weaker magnetism than the solid core, an inner weld part (W20) that is a weld part between the inner core part and the non-magnetic component and is provided on at least one side selected from the side of the movable core of the non-magnetic component and a side of the non-magnetic component (60) opposite the movable core, and an outer weld part (W10).which is a welded part between the outer core part and the non-magnetic component and is provided on a welded surface (60b) of the non-magnetic component on the same side as the inner welded part. A recess (61) is formed on a part of the welded surface between the inner welded part and the outer welded part.

Description

Cross-reference to related registration

[0001] This application is based on Japanese patent application no. 2016-148 842, filed on July 28, 2016, the disclosure of which is incorporated herein by reference. Technical field

[0002] The present disclosure relates to a fuel injection valve which injects fuel. State of the art

[0003] A fuel injection valve described in patent document 1 comprises a coil arranged in a ring, a fixed core in which a magnetic field is generated by excitation of the coil, a movable core which generates a magnetic field between the movable core and the fixed core such that the latter is drawn in, and a valve body which is driven by the drawn-in movable core and the opening / closing of an injection orifice. A non-magnetic element or component is assembled at a section located opposite the movable core outside the fixed core, a section positioned on the inner side or inside in the radial direction of the non-magnetic component outside the fixed core is referred to as an inner core section, and a section on the outer side or outside is referred to as an outer core section.

[0004] Furthermore, an attractive force generated by a magnetic field between the outer core and the movable core, as well as an attractive force generated by a magnetic field between the inner core and the movable core, are applied to the movable core, and the movable core is attracted to the fixed core by these forces. In short, the inner core, the non-magnetic component, and the outer core are positioned next to each other opposite the movable core, and thus an attractive force is generated in the movable core by both the outer and inner cores. This allows the attractive force to be increased. State of the art document (patent document)

[0005] Patent document 1: EP 2 746 565 A1

[0006] However, fuel pressure is applied to a surface opposite the moving core outside the solid core. Therefore, in a structure of the aforementioned related prior art, where the inner core, the non-magnetic component, and the outer core are arranged adjacent to each other in positions opposite the moving core, the problems described below arise. Specifically, it must be taken into account that a connecting surface of the inner core and the non-magnetic component, as well as a connecting surface of the outer core and the non-magnetic component, may be defective if the surfaces on the side opposite the moving core of the inner core, the non-magnetic component, and the outer core bear the fuel pressure.

[0007] In the meantime, for the purposes of the explanation below, it is generally understood that the non-magnetic component and the solid core are joined by welding. A welded part in a state where the inner core and the non-magnetic component are joined and fixed is referred to as an inner welded part, and a welded part in a state where the outer core and the non-magnetic component are joined and fixed is referred to as an outer welded part. Furthermore, with regard to the problem of fracture of the weld surface described above, the present inventors have investigated ways of increasing the weld depth from the weld surface and improving the joint strength.

[0008] As the weld depth increases, the thickness of the welded part, as viewed from the weld surface, also increases. It is then taken into account that the inner and outer welded parts come into contact, resulting in a magnetic short circuit, as the interval between them becomes short. When such a magnetic short circuit occurs, the magnetic flux passes between the inner and outer welded parts, potentially leading to a deterioration of the attraction force.

[0009] Further state of the art is disclosed in JP 2014 177 877 A. Summary of the invention

[0010] The present disclosure addresses the aforementioned problems. Thus, it is an objective of the present disclosure to provide a fuel injection valve that can achieve both an improvement in the connection strength and the prevention of magnetic short-circuiting between the solid core and the non-magnetic component, while employing a structure that increases the attractive force.

[0011] To achieve this task, the present disclosure employs the technical means described below.

[0012] In one aspect or embodiment of the present disclosure, a fuel injection valve for injecting fuel through an injection hole comprises a coil arranged in an annular shape, a fixed core which forms a magnetic field when the coil is energized, a movable core which is provided on the side of the injection hole of the fixed core in a direction of an annular centerline of the coil and which forms a magnetic field between the movable core and the fixed core when the coil is energized such that the latter is attracted to the fixed core, a valve body which is driven by the attracted movable core such that it opens or closes the injection hole, an inner core part which is part of the fixed core which is opposite the movable core, and an outer core part which is part of the fixed core.which is opposite the movable core and is located outside the inner core part with respect to the annular center line, a non-magnetic component that is arranged between the inner core part and the outer core part and has a weaker magnetism than the solid core, an inner weld part that is a weld part between the inner core part and the non-magnetic component and is provided on an end surface of the non-magnetic component on the side of the movable core or on an end surface of the non-magnetic component on its side opposite the movable core, and an outer weld part that is a weld part between the outer core part and the non-magnetic component and is located on a weld surface that is an end surface,The non-magnetic component is located on the same side as the inner weld. A recess is formed on part of the weld surface between the inner and outer welds.

[0013] In this configuration, the inner and outer core sections are arranged on a segment of the fixed core opposite the movable core, and the non-magnetic component is positioned between this inner core section and an outer core section. Therefore, the non-magnetic component prevents the formation of a magnetic path between the inner and outer core sections. As a result, an attractive force generated by a magnetic field between the outer core section and the movable core, as well as an attractive force generated by a magnetic field between the inner core section and the movable core, is exerted on the movable core, and the movable core is attracted to the fixed core by these forces.Therefore, the attractive force can be increased, since both the outer core part and the inner core part generate the attractive force in the movable core.

[0014] Additionally, this aspect features a recess in a section between the inner and outer welded parts, extending from the weld surface of the non-magnetic component. Even if the weld depth is increased to improve joint strength, and the weld thickness is increased, this recess prevents the inner and outer welded parts from coming into contact and causing a magnetic short circuit. Therefore, this design can achieve both an increase in weld depth to improve joint strength and the prevention of magnetic short circuits. Brief description of the drawings

[0015] The foregoing and other tasks, features, and advantages of the present disclosure will become clear from the following detailed description with reference to the accompanying drawings. These show: Fig. 1 a cross-sectional view of a fuel injector relating to a first embodiment. Fig. 2 a drawing when a solid core, a non-magnetic component 60 and a stopper are considered starting from the side of the injection hole in the first embodiment. Fig. 3 an enlarged cross-sectional view of Fig. 1. Fig. 4 an enlarged cross-sectional view of Fig. 3. Fig. 5 an enlarged cross-sectional view of Fig. 4 and a drawing showing the non-magnetic component, an inner weld part and an outer weld part. Fig. 6 a cross-sectional view of a fuel injector relating to a second embodiment and a drawing showing a non-magnetic component, an inner weld part and an outer weld part. Fig. 7 a cross-sectional view of a fuel injector relating to a third embodiment and a drawing showing a non-magnetic component, an inner weld part and an outer weld part. Fig. 8 a cross-sectional view of a fuel injector relating to a fourth embodiment and a drawing showing a non-magnetic component, an inner weld part and an outer weld part. Fig. 9 a cross-sectional view of a fuel injector relating to a fifth embodiment and a drawing showing a non-magnetic component, an inner weld part and an outer weld part. Fig. 10 a cross-sectional view of a fuel injector relating to a sixth embodiment and a drawing showing a non-magnetic component, an inner weld part and an outer weld part. Fig. 11 a cross-sectional view of a fuel injector relating to a seventh embodiment, and a drawing showing a non-magnetic component, an inner weld part and an outer weld part; and Fig. 12 a cross-sectional view of a fuel injector relating to an eighth embodiment. Embodiments for carrying out the invention

[0016] Several embodiments will be explained below with reference to the drawings. In each embodiment, there is a case where a section corresponding to a point explained in a previous aspect is marked with the same reference numeral, and a duplicate explanation is omitted. In each aspect, if only part of a configuration is explained, reference may be made to and application of other aspects previously explained with regard to other sections of the configuration. First embodiment

[0017] The fuel injector, which is located in Fig. The fuel injector shown in Figure 1 is mounted on an internal combustion engine (gasoline engine) and injects fuel directly into each combustion chamber of a multi-cylinder engine. The fuel supplied to the fuel injector is pressurized by a fuel pump (not shown), which is driven by a rotary force of the engine. The fuel injector is configured to include a casing 10, a nozzle body 20, a valve body 30, a movable core 40, a fixed core 50, a non-magnetic component 60, a coil 70, a pipe connector 80, and the like.

[0018] The housing 10 is made of a metal and has a circular cylindrical shape with a base, extending in the direction along which the annular centerline C of the coil 70 extends (which will subsequently be described as the axial direction). An opening 10b on the outflow side is formed on a bottom surface 10a of the housing 10, and an opening 10c on the inflow side is formed on the opposite side of the bottom surface 10a outside the housing 10. Furthermore, the annular centerline C of the coil 70 and the centerline of the housing 10, the nozzle body 20, the valve body 30, the movable core 40, the fixed core 50, and the non-magnetic component 60 coincide with each other.

[0019] The nozzle body 20 is made of a metal and is arranged such that it is inserted into the housing 10 starting from the opening 10c on the inlet side. The nozzle body 20 comprises a body part 21, which is positioned inside the housing 10 and engages with the bottom surface 10a, and a nozzle part 22, which extends from the opening 10b on the outlet side to the outside of the housing 10. The outer circumferential surface of the body part 21 is in contact with the inner circumferential surface of the housing 10. The nozzle part 22 has a circular cylindrical shape extending in the axial direction, and an injection orifice component 23 is attached to the distal end of the nozzle part 22.

[0020] The injection hole component 23 is made of a metal and fixed to the nozzle part 22 by welding. The injection hole component 23 has a circular cylindrical shape with a base, extending in the axial direction, and injection holes 23a, which inject fuel, are formed at the distal end of the injection hole component 23. A seating surface 23s is formed on the inner circumferential surface of the injection hole component 23, with the valve body 30 extending away from and bearing against the seating surface 23s.

[0021] The valve body 30 is made of metal and has a circular column shape extending along the axial direction. The valve body 30 is assembled on the inside of the nozzle body 20 in a state that is movable in the axial direction, and an annular fuel passage 22b, extending in the axial direction, is formed between an outer circumferential surface 30a of the valve body 30 and an inner circumferential surface 22a of the nozzle body 20. At one end on the side of the injection hole 23a of the valve body 30, an annular seat surface 30s is formed, which extends away from and bears against the seat surface 23s.At one end of the opposite side of the injection hole 23a (which will be described below as the opposite side of the injection hole) outside the valve body 30, a fuel passage 30b is formed which extends in the axial direction, and a through-hole 30c is formed which ensures that the fuel passage 30b inside the valve body 30 and the fuel passage 22b on an outside of the valve body 30 are connected to each other.

[0022] The movable core 40 is made of metal, has a disc shape, and is arranged such that it is housed in a housing chamber 21a, which has a recess formed on the opposite side of the injection hole of the body part 21. The movable core 40 is fixed at the end opposite the injection hole of the valve body 30. More precisely, the valve body 30 is arranged such that it is inserted into a through-hole 41 formed at the center of the movable core 40. At the end opposite the injection hole of the valve body 30, an engagement part 31 is formed, which extends in the radial direction of the valve body 30.The engagement part 31 is fitted into a recessed portion of the movable core 40 to engage with it, and the movable core 40 and the valve body 30 are welded together in such a way that the engagement part 31 is in contact with the bottom surface 42 of the recessed portion. Therefore, the movable core 40 moves integrally with the valve body 30 in the axial direction. The surfaces opposite the injection hole of the movable core 40 and the engagement part 31 are positioned such that they are coplanar and are perpendicular to the axial direction.

[0023] The solid core 50 comprises an outer core part 51, an inner core part 52, and a cap part 53, which are explained below. The solid core 50 is arranged to be fixed to the inside of the housing 10. The structure of the solid core 50 is described below using Fig. 2, Fig. 3 and Fig. 4 in addition to Fig. 1 will be explained.

[0024] The outer core part 51 is made of a metal having an annular shape extending around the axial direction, and the outer circumferential surface of the outer core part 51 is in contact with the inner circumferential surface of the housing 10. A lower end surface 51a on the side of the injection hole of the outer core part 51 is in contact with an upper end surface 21b of the body part 21. Starting from the lower end surface of the outer core part 51, a section which receives fuel pressure from the housing chamber 21a is referred to as an outer pressure-receiving surface 51b, and a section which is opposite the movable core 40, starting from the outer pressure-receiving surface 51b, is referred to as an outer opposite surface 51c.The lower end surface of the non-magnetic component 60 is referred to as a non-magnetic opposite surface 60a, and the lower end surface of the inner core part 52 is referred to as an inner opposite surface 52a. The outer opposite surface 51c, the non-magnetic opposite surface 60a, and the inner opposite surface 52a are opposite the upper end surface of the movable core 40. Furthermore, these opposite surfaces are positioned such that they are coplanar and are arranged perpendicular to the axial direction.

[0025] The inner core part 52 is arranged radially on the inner side of the outer core part 51 and is made of a metal having an annular shape extending around the axial direction. The inner circumferential surface of the inner core part 52 functions as a fuel passage 52r. The non-magnetic component 60 has an annular shape and is located between the inner core part 52 and the outer core part 51. It is made of a material with weaker magnetism compared to the outer core part 51 and the inner core part 52. Conversely, the outer core part 51, the inner core part 52, the movable core 40, and the cap part 53 are made of a magnetizing material, with the cap part 53 being described below.

[0026] A stopper 54, which has a circular cylindrical shape and is made of metal, is fixed to the inner circumferential surface of the inner core part 52. A lower end surface 54a of the stopper 54 is positioned axially on the side of the injection hole of the inner opposite surface 52a. Therefore, in a state where an upper end surface 31a of the engagement part 31 of the valve body 30 is in contact with the lower end surface 54a of the stopper 54, the inner opposite surface 52a, the non-magnetic opposite surface 60a, and the outer opposite surface 51c are not in contact with the movable core 40 and have a gap G between the upper end surface of the movable core 40 and both the inner opposite surface 52a, the non-magnetic opposite surface 60a, and the outer opposite surface 51c.

[0027] The coil 70 is arranged on the opposite side of the injection hole of the non-magnetic component 60 and on the outer side in the radial direction of the inner core part 52. The coil 70 is wound around a coil carrier 71 made of a resin. The coil carrier 71 has a circular cylindrical shape with the axial direction as its center point. Therefore, the coil 70 is arranged in an annular shape extending around the axial direction. The lower end surface of the coil carrier 71 is in contact with the non-magnetic component 60, and the inner circumferential surface of the coil carrier 71 is in contact with the inner core part 52. An opening on the outer circumferential side and an upper end surface of the coil carrier are covered by a cover 72 made of a resin.Furthermore, the annular outer circumferential surface of the coil 70 is positioned on the outer side in the radial direction of the outer circumferential surface of the movable core 40 in a cross-section which includes the annular center line C.

[0028] The cap part 53 is made of a magnetic metal, is shaped in an annular form, and is located on the outer side in the radial direction of the inner core part 52 and above the outer core part 51. The outer circumferential surfaces of the cap part 53, the outer core part 51, and the body part 21 are in contact with the inner circumferential surface of the housing 10 and are located within the housing 10.

[0029] On the opposite side of the injection hole of the inner core part 52 is the pipe connection part 80, which configures a fuel inlet port 80a and is connected to an external pipeline. The pipe connection part 80 is made of metal and is formed from a single metal component that is integral to the inner core part 52. Fuel is supplied to the fuel injection valve through the inlet port 80a, which is pressurized by a high-pressure pump.

[0030] A press-fit component 82 is press-fitted to a press-fit component 80b, which is arranged in a portion of a through-hole formed in the pipe connection part 80, and a resilient component 82s is arranged on the injection port side of the press-fit component 82. One end of the resilient component 82s abuts the press-fit component 82, and the other end abuts the engagement part 31. Therefore, the amount of resilient deformation of the resilient component 82s at the time when the valve body 30 opens to the full stroke position, namely at the time when the engagement part 31 abuts the stopper 54, is determined according to the press-fit amount of the press-fit component 82, namely, or in particular, the fixed position in the axial direction. This means that the valve closing force (actuating force) is adjusted by the spring-loaded component 82s by the press-fitted amount of the press-fitted component 82.

[0031] An annular pressure surface 80c is formed on the outer circumferential surface of the pipe fitting 80, extending perpendicular to the axial direction. A fastening component 81 adjoins the pressure surface 80c. By attaching a threaded part 81n, formed on the outer circumferential surface of the fastening component 81, to a threaded part 10n, formed on the inner circumferential surface of the housing 10, the fastening component 81 is secured to the housing 10. By adjusting this fastening force, a force is adjusted with which the pressure surface 80c is pressed through the fastening component 81 (which is subsequently described as an axial force F10). Furthermore, the inner core part 52, the non-magnetic component 60, the outer core part 51 and the body part 21 are sandwiched between the bottom surface 10a of the housing 10 and the fastening component 81 by this axial force F10.

[0032] Next, a procedure for assembling the fuel injector will be explained.

[0033] First, the nozzle body 20 is positioned in a state where the injection hole component 23 is welded, and the valve body 30 is positioned in a state where it is inserted into the through-hole 41 of the movable core 40. Next, the valve body 30 is inserted into the inner circumferential surface 22a of the nozzle body 20, and the movable core 40 is positioned in the housing chamber 21a. Subsequently, the nozzle body 20, with the valve body 30 thus positioned in the insertion position, is inserted into the opening 10b on the outlet side of the housing 10.

[0034] On the other hand, in a state where the non-magnetic component 60 is arranged between the inner core part 52 and the outer core part 51, the inner core part 52 and the non-magnetic component 60 are welded and fixed together, and the outer core part 51 and the non-magnetic component 60 are also welded and fixed together. Furthermore, the stopper 54 is welded to and fixed to the inner core part 52. Then, the coil carrier 71, with the coil 70 wound around it, is inserted into the outer circumferential surface of the inner core part 52. Additionally, the cover 72 is formed from resin to cover the coil 70 and the coil carrier 71, and the cap part 53 is inserted into the outer circumferential surface of the inner core part 52.

[0035] Next, the solid core 50, in a state where the coil 70, the cap part 53, and the like are thus attached, is inserted into the housing 10, in a state where the nozzle body 20 and the like are attached, and the fastening component 81 is fastened to the casing 10 with a predetermined torque. Furthermore, the press-fit component 82 is press-fitted onto the press-fit component 80b, while the press-fit quantity is adjusted to obtain a predetermined actuating force, after the spring component 82s is inserted into the through-hole formed in the inner core part 52. Thus, the assembly of the fuel injector is completed.

[0036] Next, using Fig. 5 the welded part of the outer core part 51 and the inner core part 52 as well as the non-magnetic component 60 are explained in detail.

[0037] A section in which the inner core part 52 and the non-magnetic component 60 are in contact with each other is welded outside the inner core part 52 and the non-magnetic component 60, which is a section of an area from the end surface on the opposite side of the injection hole of the non-magnetic component 60 to a predetermined depth, and the welded part is referred to as an inner weld part W20. That is, the inner weld part W20 is a section that is connected to the dot matrix of Fig. 5 is marked, and this is a section in which part of the inner core part 52 and part of the non-magnetic component 60 are heated and joined, and then brought into a cooled and solidified state.

[0038] A section in which the outer core part 51 and the non-magnetic component 60 are in contact with each other is welded outside the outer core part 51 and the non-magnetic component 60, which is a section of an area from the end surface on the opposite side of the injection hole of the non-magnetic component 60 to a predetermined depth, and the welded part is referred to as an outer weld part W10. That is, the outer weld part W10 is a section that is connected with the dot matrix of Fig. 5 is marked, and this is a section in which part of the outer core part 51 and part of the non-magnetic component 60 are heated and joined, and then brought into a cooled and solidified state.

[0039] Furthermore, in Fig. 1, Fig. 3 and Fig. 4. A representation of these welded parts has been omitted, and an unwelded state is shown. Therefore, a portion of an inner tapered surface 52f and an outer tapered surface 51f, which is shown in Fig. 1, Fig. 3 and Fig. As illustrated in section 4, the welded part actually disappeared.

[0040] The outer weld part W10 and the inner weld part W20 are arranged on the same side of an end surface (a weld surface 60b), starting from the end surface on the side of the injection hole and the end surface on the opposite side of the injection hole of the non-magnetic component 60. A groove 61 is formed as a recess in a section between the inner weld part W20 and the outer weld part W10, starting from the weld surface 60b. The cross-sectional shape of the groove is rectangular, as shown in Fig. Figure 5 shows that the cross-sectional shape of the groove is rectangular, with the radial direction of the solid core 50 being the longitudinal direction of the groove. The groove 61 is formed in the central part in the radial direction starting from the weld surface 60b and is formed in an annular shape extending around the axial direction, as shown in Figure 5. Fig. 2 is shown.

[0041] The weld depth dimension from the weld surface 60b outside the inner weld area W20 is referred to as the inner weld depth, the weld depth dimension from the weld surface 60b outside the outer weld area W10 is referred to as the outer weld depth, and the dimension from the weld surface 60b to the bottom surface 61a of the groove 61 is referred to as the groove depth (depression depth). In the example of Fig. 5. The weld depth direction is a direction along the outer tapered surface 51f or the inner tapered surface 52f, and the dimension of the weld extending in this direction is equivalent to the weld depth. Furthermore, the groove depth is equivalent to the dimension in the axial direction from the weld surface 60b to the bottom surface 61a. The groove depth is also set to a dimension smaller than both the inner and outer weld depths. Additionally, the position of the bottom surface 61a in the axial direction is opposite the injection hole of a distal end piece W13 on the side of the injection hole of the outer weld piece W10 and of a distal end piece W23 on the side of the injection hole of the inner weld piece W20.

[0042] Part of the outer weld section W10 and part of the inner weld section W20 are exposed at the weld surface 60b. This exposed section has a shape that extends radially along the weld surface 60b. In particular, the sections extending towards the side approaching the groove 61 are referred to as weld extension sections W11, W21, and distal ends W12, W22 of the weld extension sections W11, W21 are exposed extending from the wall surface of the groove 61. In the example of Fig. 5 the distal ends W12, W22 of the extension are exposed from the side surfaces 61b, 61c of the groove 61, and the distal ends W12, W22 of the extension have a shape that extends circumferentially along the groove 61.

[0043] Next, the actions of the fuel injector will be explained.

[0044] The high-pressure fuel, supplied to the fuel injector from the high-pressure pump, flows in from the inlet port 80a, through the through-hole of the inner core part 52 into the fuel passage 30b of the valve body 30, and from the through-hole 30c into the fuel passage 22b. Additionally, the high-pressure fuel passes within the fuel passage 22b between the seat surface 30s and the seat surface 23s and is injected from the injection holes 23a when the valve body 30 is operated in such a way that it opens, as explained below. Furthermore, the housing chamber 21a is filled with the high-pressure fuel, and the pressure of this high-pressure fuel is applied to the lower end surfaces of the inner core part 52, the non-magnetic component 60, and the outer core part 51.

[0045] When the valve body 30 is operated in such a way that it opens, the coil 70 is energized. Subsequently, as indicated by an arrow with a dashed line from Fig. Figure 3 shows how a magnetic field is generated around the coil 70. This means that, upon excitation, a magnetic field circuit is formed in which the magnetic flux passes through the outer core part 51, the movable core 40, the inner core part 52, and the cap part 53 in this sequence. At this time, the non-magnetic component 60 acts to prevent a magnetic short circuit between the outer core part 51 and the inner core part 52. When the magnetic flux passes through such a magnetic circuit, an attractive force is exerted on the movable core 40, drawing it towards the fixed core 50.More precisely, an attractive force is generated by a magnetic flux M1 passing between the outer core part 51 and the movable core 40, as well as an attractive force generated by a magnetic flux M2 passing between the inner core part 52 and the movable core 40. Furthermore, the inner opposite surface 52a and the outer opposite surface 51c of the solid core 50 are equivalent to an attractive surface of the solid core, which attracts the movable core 40 by exciting the coil 70.

[0046] A valve closing force is applied to the movable core 40 and the valve body 30 by the spring component 82s, a valve closing force by the fuel pressure, and a valve opening force by the attractive force described above. Since the attractive force is set so that the valve opening force becomes greater than these valve closing forces when it is generated (triggered by excitation), the movable core 40 moves together with the valve body 30 towards the side of the fixed core 50. This causes the valve body 30 to open and come into contact with the stopper 54, so that the seat surface 30s moves away from the seat surface 23s, and the high-pressure fuel is injected from the injection holes 23a.

[0047] When the valve body 30 is operated in such a way that it closes, the excitation of the coil 70 is stopped. Subsequently, the valve body 30 is operated in such a way that it closes together with the movable core 40 due to the valve closing force through the spring component 82s, and the seat surface 30s engages with the seat surface 23s, since the valve opening force disappears due to the attractive force described above. This stops fuel injection from the injection holes 23a.

[0048] Next, the connection surface of the outer core part 51 and the non-magnetic component 60, as well as the connection surface of the inner core part 52 and the non-magnetic component 60, will be explained in detail.

[0049] The entire surface of a surface connected to the non-magnetic component 60 outside the inner core part 52 is formed in a plane inclined with respect to the annular centerline C in a cross-section that includes the annular centerline C, and this connecting surface will subsequently be described as the inner tapered surface 52f. Furthermore, the entire surface of a surface connected to the non-magnetic component 60 outside the outer core part 51 is formed in a plane inclined with respect to the annular centerline C in a cross-section that includes the annular centerline C, and this connecting surface will subsequently be described as the outer tapered surface 51f.

[0050] The inner tapered surface 52f and the outer tapered surface 51f have a shape that extends annularly around the annular centerline C and are inclined in the same direction with respect to the axial direction. More precisely, the inner tapered surface 52f and the outer tapered surface 51f are inclined in such a direction that their dimensions decrease in the radial direction as they approach the side of the injection hole in the axial direction. Furthermore, the inner tapered surface 52f and the outer tapered surface 51f have a linear shape in a cross-section that includes the annular centerline C.In short, it can be said that the non-magnetic component 60 has a circular cylindrical shape, the dimension of which decreases in the radial direction as it approaches the side of the injection hole.

[0051] The axial length of the inner core part 52 is longer than the axial length of the outer core part 51. More precisely, the upper end of the outer core part 51 is positioned on the lower side (injection hole side) of the lower end of the coil 70, whereas the upper end of the inner core part 52 is positioned on the upper side (opposite side of the injection hole) of the lower end of the coil 70. More precisely, the upper end of the inner core part 52 is positioned on the upper side (opposite side of the injection hole) of the upper end of the coil 70.

[0052] The upper end position in the axial direction of the outer tapered surface 51f is the same as the upper end position in the axial direction of the inner tapered surface 52f and the lower end position in the axial direction of the outer tapered surface 51f is the same as the lower end position in the axial direction of the inner tapered surface 52f.

[0053] In a cross-section that includes the annular centerline C, an inclination angle of the inner tapered surface 52f with respect to the annular centerline C is referred to as an inner inclination angle 52θ, and an inclination angle of the outer tapered surface 51f with respect to the annular centerline C is referred to as an outer inclination angle 51θ (compare Fig. 3) Furthermore, the inner tilt angle 52θ and the outer tilt angle 51θ are set to angles that differ from each other. More precisely, the inner tilt angle 52θ is set to a smaller angle compared to the outer tilt angle 51θ.

[0054] Next, a force applied to both the solid core 50, the non-magnetic component 60 and the stopper 54 will be explained.

[0055] As in Fig. As shown in Figure 1, the inner core part 52, the non-magnetic component 60, the outer core part 51, and the body part 21 are sandwiched between the bottom surface 10a of the housing 10 and the mounting component 81 by attaching the mounting component 81 to the housing 10. This means that a reaction force F30, opposing an axial force applied to the pressure surface 80c, is applied to the body part 21 from the bottom surface 10a, and a reaction force F20, equal to this reaction force F30, is applied to the lower end surface 51a of the outer core part 51 from the upper end surface 21b of the body part 21.The fastening component 81 is equivalent to an inner application part, which applies the axial force F10 in the axial direction to the inner core part 52, and applies the axial force F10 in the direction in which the inner core part 52 is pressed towards the side of the movable core 40. The body part 21 of the nozzle body 20 is equivalent to an outer application part, which applies the reaction force F20 opposite to the axial force F10 to the outer core part 51, and applies the reaction force F30 in the direction in which the outer core part 51 is pressed towards the opposite side of the movable core 40.

[0056] Although the axial force F10 is applied to the solid core 50 by the fastening component 81 and the reaction force F20 by the body part 21, a shear stress is generated inside the solid core 50 because the position in the radial direction to which the axial force F10 is applied is located on the inner side of the position in the radial direction to which the reaction force F20 is applied. Therefore, a shear force is applied to the junction surface of the inner core part 52 and the non-magnetic component 60, as well as to the junction surface of the outer core part 51 and the non-magnetic component 60, thus causing failure of the weld joint at the junction surfaces described above.

[0057] With regard to this problem, in the present embodiment the inner tapered surface 52f and the outer tapered surface 51f are manufactured such that they are arranged inclined in a direction such that the non-magnetic component 60 is sandwiched in place by the axial force F10 and the reaction force F20. More precisely, the inner tapered surface 52f and the outer tapered surface 51f are manufactured such that they are arranged inclined in a direction such that forces from compressive components F11a, F21a, which are in Fig. 4 are shown, generated. In other words, the inner tapered surface 52f and the outer tapered surface 51f are manufactured such that they are arranged inclined in such a direction that the surface which is in contact with the outer core part 51 outside the non-magnetic component 60 absorbs the reaction force F20 in the compressive direction and the surface which is in contact with the inner core part 52 outside the non-magnetic component 60 absorbs the axial force F10 in the compressive direction.

[0058] Starting from the reaction force F20, a force F21, which is transmitted to the outer tapered surface 51f, is divided into the compressive component F21a and a shear component F21b, wherein the compressive component F21a runs perpendicular to the outer tapered surface 51f, and the shear component F21b runs parallel to the outer tapered surface 51f. Starting from the axial force F10, a force F11, which is transmitted to the inner tapered surface 52f, is divided into the compressive component F11a and a shear component F11b, wherein the compressive component F11a runs perpendicular to the inner tapered surface 52f, and the shear component F11b runs parallel to the inner tapered surface 52f.In the present embodiment, the directions of the respective compressive components F21a, F11a do not coincide, and the directions of the respective shear components F21b, F11b also do not coincide, since the inner inclination angle 52θ and the outer inclination angle 51θ are made to angles that differ from each other.

[0059] In a state where the inner core part 52 and the outer core part 51 do not bear the pressure of the fuel from the side of the movable core 40, namely in a state where, for example, the fuel injection valve is not yet in use, the inner core part 52 and the outer core part 51 are in a state where they are resiliently deformed by the axial force F10 and the reaction force F20. That is, the fixed core 50 is compressed by screwing the fastening component 81 onto the threaded part 10n with a predetermined torque.

[0060] When the fuel injector is used in a state where a preload is applied to the solid core 50, as the pressure absorbed by the high-pressure fuel in the housing chamber 21a is applied to the solid core 50, the amount of spring deformation is reduced by the preload. More precisely, the outer pressure-bearing surface 51b of the outer core part 51, the inner opposing surface 52a of the inner core part 52, the non-magnetic opposing surface 60a of the non-magnetic component 60, and the lower end surface 54a of the stopper 54 absorb the pressure of the high-pressure fuel.In the explanation below, a force acting on the inner core part 52, on the opposite side of the injection hole, is referred to as an internal fuel pressure boost force due to the fuel pressure applied to the inner opposite surface 52a and the lower end surface 54a. Furthermore, the force F11 applied to the inner tapered surface 52f is reduced by a portion of the internal fuel pressure boost force. During this reduction, the reaction force F20 applied to the lower end surface 51a also becomes small, and the force F21, derived from the reaction force F20 and transferred to the outer tapered surface 51f, also becomes small.Furthermore, the fastening torque of the fastening component 81 is adjusted such that the force F11, which is derived from the axial force F10 applied to the inner tapered surface 52f, does not become smaller than the internal fuel pressure force.

[0061] As described above, when the fuel injector is used, although the internal fuel pressure boost force is applied to the solid core 50, a preload is applied to the solid core 50 beforehand. This prevents the inner core part 52 from being pushed upwards towards the top (opposite the injection hole) by the internal fuel pressure boost force, thus preventing a positional displacement. Furthermore, deterioration of the flatness of a surface located outside the solid core opposite the movable core 40, caused by deformation due to the internal fuel pressure boost force, is prevented, and a deterioration of the attractive force is also prevented.

[0062] Next, the actions and effects of a configuration used by the present embodiment will be explained.

[0063] In the fuel injection valve of the present embodiment, the inner core part 52 and the outer core part 51 are arranged in a section that is positioned opposite the movable core 40 outside the fixed core 50, and the non-magnetic component 60 is arranged between the inner core part 52 and the outer core part 51. Therefore, the non-magnetic component 60 prevents the formation of a magnetic path between the inner core part 52 and the outer core part 51. As a result, both an attractive force generated by the magnetic flux M1 passing between the outer core part 51 and the movable core 40, and an attractive force generated by the magnetic flux M2 passing between the inner core part 52 and the movable core 40, are applied to the movable core 40.This means that not only is an attractive force exerted on the movable core 40 by a magnetic flux in the direction emanating from it, but also by an attractive force exerted on it by a magnetic flux in the direction entering the movable core 40. Therefore, the attractive force is increased.

[0064] In the meantime, it is necessary to increase the radial dimensions of the movable core 40 and the fixed core 50, although the attractive force can be increased if the attractive force is thus applied to both of the magnetic fluxes M1 and M2. However, if the radial dimension of the fixed core 50 is increased, it must be taken into account that the pressure-bearing area for the pressure absorbed axially by the fixed core 50 from the fuel of the housing chamber 21a becomes large, and the interface between the fixed core 50 and the non-magnetic component 60 becomes defective.

[0065] To address this problem, the present embodiment provides the fastening component 81 and the body part 21, wherein the fastening component 81 applies the axial force F10 in the axial direction to the inner core part 52, and the body part 21 applies the reaction force F20 opposite to the axial force F10 to the outer core part 51. Furthermore, the fixed core 50 is in a state in which it does not absorb the fuel pressure from the side of the movable core 40, but rather is resiliently deformed by the axial force F10 and the reaction force F20. Therefore, fracture of the connection surface due to the internal fuel pressure boost force can be prevented by a preload applied to the fixed core 50 in advance, as described above.

[0066] However, if such a configuration is used to apply a preload, a fracture of the connection surface due to the axial force F10, which generates a preload, is again taken into account. Therefore, in the present embodiment, the connection surface against the non-magnetic component 60 outside the inner core part 52 is manufactured such that it has a tapered shape, and the connection surface against the non-magnetic component 60 outside the outer core part 51 is manufactured such that it has a tapered shape, while such a configuration is used to apply a preload.Furthermore, these connecting surfaces, namely the inner tapered surface 52f and the outer tapered surface 51f, are arranged inclined in the same direction with respect to the annular center line C, and more precisely, they are arranged inclined in the direction in which the non-magnetic component 60 is sandwiched in by the axial force F10 and the reaction force F20.

[0067] Therefore, when screwing the fastening component 81 to the threaded part 10n and applying the preload described above, it is possible to avoid the entire axial force F11 being transferred to the inner tapered surface 52f, originating from the axial force F10, by applying the screw force as a shear force to the inner tapered surface 52f. That is, the axial force F11 is dispersed into the compressive component F11a and the shear component F11b, and the shear component F11b is reduced by a portion of the compressive component F11a. Similarly, the reaction force F21, which is transferred to the outer tapered surface 51f, is dispersed into the compressive component F21a and the shear component F21b, and the shear component F21b is reduced by a portion of the compressive component F21a.Accordingly, the shear force applied to the inner tapered surface 52f and the outer tapered surface 51f can be reduced, and therefore such a problem can be prevented as to the joining surface being defective due to the axial force F10, which creates a preload.

[0068] The effects described above are summarized as follows. The inner core part 52 and the outer core part 51 are arranged in a section that is positioned opposite the movable core 40 outside the fixed core 50. The non-magnetic component 60 is positioned between the inner core part 52 and the outer core part 51, thereby increasing the attractive force using the two magnetic fluxes M1 and M2. Furthermore, the mounting component 81, which applies the axial force F10, and the body part 21, which applies the reaction force F20, are provided. The fixed core 50 is in a state of spring deformation due to the axial force F10, and the reaction force F20 is in a state in which it does not absorb the fuel pressure.Therefore, fracture of the interface surface due to the internal fuel pressure boost force in a state where the fuel pressure is absorbed can be prevented by preloading. Furthermore, the inner tapered surface 52f and the outer tapered surface 51f are designed to be inclined in the same direction and in a direction in which the non-magnetic component 60 is sandwiched between them by the axial force F10 and the reaction force F20. Accordingly, when the axial force F10 is applied and the preload is generated, the shear force applied to the inner tapered surface 52f and the outer tapered surface 51f can be reduced, thus preventing fracture of the interface surface.Therefore, both an increase in the attractive force and a prevention of fracture of the connecting surface of the solid core 50 and the non-magnetic component 60 can be achieved.

[0069] As explained above, an increase in fuel pressure, as described above, increases the shear force applied to the inner tapered surface 52f and the outer tapered surface 51f, leading to a problem of joint surface fracture. To address this problem, the strength of the joint surface can be increased by increasing the depth of the outer weld section W10 and the inner weld section W20.

[0070] However, the welded part becomes thicker because it is thus recessed. This means that the dimension in the radial direction of the outer welded part W10 and the inner welded part W20 increases. In particular, the extension length of the weld extensions W11 and W21 becomes longer. As a result, the interval between the distal end of the weld extension W11 of the outer welded part W10 and the distal end of the weld extension W21 of the inner welded part W20 becomes short. When the distal ends of the weld extensions W11 and W21 come into contact with each other, the inner core part 52 and the outer core part 51 are magnetically short-circuited. In this case, the magnetic flux M1 and M2 passes directly between the inner core part 52 and the outer core part 51 without passing through the movable core 40, and the attractive force is reduced.

[0071] With regard to the problem of magnetic short-circuiting, in the present embodiment, the groove 61 is formed in a section between the inner weld section W20 and the outer weld section W10, extending from the weld surface 60b of the non-magnetic component 60. Even if the weld depth is increased to improve the joint strength, and the weld thickness is increased, the groove 61 prevents the inner weld section W20 and the outer weld section W10 from coming into contact and causing a magnetic short circuit. More precisely, the groove 61 restricts the weld extensions W11 and W21 from extending along the weld surface 60b. Therefore, both an increase in weld depth to improve the joint strength and the prevention of magnetic short-circuiting can be achieved.

[0072] In the present embodiment, the following actions and effects are also performed.

[0073] In the present embodiment, the inner weld section W20 and the outer weld section W10 are exposed from the wall surface of the groove 61. More precisely, the distal ends W12, W22 of the extension from the side surfaces 61b, 61c of the groove 61 are exposed. This means that the weld thickness is sufficiently large for the inner weld section W20 and the outer weld section W10 to reach the groove 61, and it is possible to sufficiently increase the strength of the joint surface through the weld section without causing a magnetic short circuit.

[0074] In this process, a shallow section expands in the direction of the weld depth, compared to a deep section located away from the weld surface 60b. Near the weld surface 60b, outside the welded part, this expansion is reliable in the radial direction of the non-magnetic component 60. Therefore, the effect of preventing magnetic short-circuiting is achieved more effectively with the groove positioned opposite the shallow section of the welded part compared to the groove positioned opposite the deep section. In the present embodiment, this is taken into account by setting the depth of the groove 61 smaller than the depth of the inner welded part W20 and the depth of the outer welded part W10.Therefore, the depth of the groove 61 is reduced to a mere minimum and a deterioration of the strength of the non-magnetic component 60 can be prevented, while the effect of avoiding magnetic short circuits is sufficiently exerted.

[0075] Furthermore, in the present embodiment, the inner weld part W20 and the outer weld part W10 are positioned in the direction of the annular centerline C on the side of the attraction surface of the solid core opposite the movable core 40. This attraction surface of the solid core is a surface of the solid core 50 that faces the movable core 40. More precisely, the inner weld part W20 and the outer weld part W10 are arranged on the end surface opposite the injection hole of the solid core 50. Thus, a deterioration of the attraction force resulting from the presence of the weld part can be prevented, since such an event can be avoided by ensuring that the weld part is positioned coplanar to the attraction surface of the solid core.

[0076] In the present embodiment, the outer application part is positioned on the side of the outer circumference of the movable core 40, even though the axial force F10, in the direction in which the inner core part 52 is pressed, is applied to the side of the movable core 40, and the reaction force F20, in the direction in which the outer core part 51 is pressed, is applied to the opposite side of the movable core 40. This leads to problems such as difficulty in ensuring the dimension in the radial direction of the movable part 40 and difficulty in ensuring the large attraction surface of the movable part 40, which is arranged opposite the outer core part 51.With regard to this problem, in the present embodiment the inner tapered surface 52f and the outer tapered surface 51f are manufactured such that they are inclined in a direction such that the dimension in the radial direction becomes smaller as the position on the tapered surface moves closer to the movable core 40. Therefore, it is easy to ensure a large attractive surface area for the movable part 40, which faces the outer core part 51.

[0077] Furthermore, in the present embodiment, the annular outer circumferential surface of the coil 70, in the cross-section which includes the annular center line C, is positioned on the outer side in the radial direction of the outer circumferential surface of the movable core 40. In this case, it is necessary to increase the area of ​​a section which is arranged opposite the outer surface 51c outside the outer core part 51 in order to increase the passage area of ​​the magnetic flux M1 which passes through the outer core part 51 and the movable core 40.On the other hand, in the present embodiment, the area of ​​a section which is opposite the outer opposing surface 51c outside the outer core part 51 can be increased, since the inner tapered surface 52f and the outer tapered surface 51f are manufactured in such a way that they are arranged inclined in such a direction that the dimension in the radial direction becomes smaller as the position on the tapered surface leads closer to the movable core 40.

[0078] Furthermore, in the present embodiment, the inclination angle 51θ of the outer tapered surface 51f with respect to the annular centerline C is set larger in the cross-section containing the annular centerline C compared to the inclination angle 52θ of the inner tapered surface 52f with respect to the annular centerline C. Accordingly, the pass-through area or pass-through region of the magnetic flux M1 passing through the outer core part 51 and the movable core 41 can be easily ensured, since the area of ​​a section opposite the outer surface 51c outside the outer core part 51 can be increased.

[0079] Furthermore, in the present embodiment, a stopper 54 is provided which restricts the movement of the valve body 30 in the valve opening direction by being fixed to the inner core part 52 and adjacent to the valve body 30, and the length in the axial direction of the inner core part 52 is set longer than the length in the axial direction of the outer core part 51. Therefore, the bending stiffness of the inner core part 52 with respect to the internal fuel pressure boost force is increased by a section corresponding to one in which the length in the axial direction of the inner core part 52 is made longer than the length in the axial direction of the outer core part 51.Therefore, the amount of deformation in the axial direction of the inner core part 52, generated by the preload, can be small, and the amount of deformation in the axial direction of the inner core part 52, generated by the internal fuel pressure boost force, will also be small. Accordingly, the positional accuracy in the axial direction of the stopper can be improved, and the accuracy of the gap G between the fixed core 50 and the moving core 40 in a valve opening state can be improved.

[0080] Furthermore, in the present embodiment, the inner tapered surface 52f and the outer tapered surface 51f have a shape that extends annularly around the annular center line C. Therefore, the effect described above is intensified to such an extent that the shear force applied to the inner tapered surface 52f and the outer tapered surface 51f can be reduced compared to a case in which a tapered surface is partially formed in the circumferential direction.

[0081] In the present embodiment, the inner tapered surface 52f and the outer tapered surface 51f are formed over the entire surface of a surface that connects with the non-magnetic component 60 in the cross-section containing the annular center line C. Therefore, the effect described above is amplified to such an extent that the shear force applied to the inner tapered surface 52f and the outer tapered surface 51f can be reduced compared to a case where part of the connecting surface is partially tapered in the cross-section described above. Second embodiment

[0082] In the first embodiment described above, the inner welded part W20 and the outer welded part W10 are exposed starting from the wall surface of the groove 61. On the other hand, in the present embodiment, which is described in Fig. As shown in Figure 6, the inner weld part W20 and the outer weld part W10 are not exposed from the wall surface of the groove 61, and the distal ends W12, W22 of the extension do not reach the groove 61. Even if the weld parts thus do not reach the groove 61, the effect of being able to cause the problem of a magnetic short circuit is still present, compared to the case where the groove 61 is not formed. Third embodiment

[0083] In the first embodiment described above, the inner welded part W20 and the outer welded part W10 are formed on the end surface on the opposite side of the injection hole, outside the non-magnetic component 60. On the other hand, in the present embodiment, which is described in Fig. As shown in Figure 7, the inner weld part W20 and the outer weld part W10 are formed on the final surface (weld surface) on the side of the injection hole outside the non-magnetic component 60.

[0084] Furthermore, in the present embodiment, the inner weld part W20 and the outer weld part W10 are exposed from the wall surface of the groove 61 in a similar manner to the first embodiment described above. In addition, the position of the bottom surface 61a of the groove 61 is positioned axially on the side of the injection hole of the distal end part W13, opposite the injection hole of the outer weld part W10, and the position of the distal end part W23 is opposite the injection hole of the inner weld part W20. That is, the depth of the groove 61 is set smaller than the depth of the inner weld part W20 and the depth of the outer weld part W10.

[0085] Based on the foregoing, the present embodiment also exerts the following effects through the groove 61. That is, even if the weld depth is increased to improve the joint strength, and the weld thickness increases, the groove 61 prevents the inner weld part W20 and the outer weld part W10 from coming into contact with each other and causing a magnetic short circuit. Therefore, both an increase in weld depth to improve the joint strength and the prevention of a magnetic short circuit can be achieved. Fourth embodiment

[0086] In the third embodiment described above, the surface of the inner weld part W20 and the outer weld part W10 is positioned on the attraction surface of the solid core. On the other hand, in the present embodiment, which is described in Fig. As shown in Figure 8, the inner weld part W20 and the outer weld part W10 are positioned in the axial direction on the side of the attraction surface of the solid core opposite the movable core 40, namely on the opposite side of the injection hole of the attraction surface of the solid core.

[0087] More precisely, the end surface on the side of the injection hole of the non-magnetic component 60 is positioned opposite the injection hole of the attraction surface of the solid core by the inner opposite surface 52a and the outer opposite surface 51c, by shortening the length in the axial direction of the non-magnetic component 60. This results in the weld being positioned in the axial direction on the side of the attraction surface of the solid core opposite the movable core 40 (on the opposite side of the injection hole of the attraction surface of the solid core), even though the weld is formed at its end surface on the side of the injection hole of the non-magnetic component 60.

[0088] Based on the foregoing, according to the present embodiment, the welded part is positioned in the direction of the annular centerline C on the side of the attraction surface of the solid core opposite the movable core 40, although the welded part is formed at its end surface on the side of the injection hole of the non-magnetic component 60. Therefore, a deterioration of the attraction force resulting from the presence of the welded part can be prevented, since such an event can be avoided by the welded part being designed to be coplanar to the attraction surface of the solid core, while at its end surface the welded part is formed on the side of the injection hole of the non-magnetic component 60.

[0089] Furthermore, according to the present embodiment, the event of fuel entering the junction surface of the inner core part 52 and the non-magnetic component 60, as well as the junction surface of the outer core part 51 and the non-magnetic component 60, can be prevented because the welded part is formed on the end surface on the side of the injection hole of the non-magnetic component 60. Therefore, a fracture of the junction surface of the inner core part 52 and the non-magnetic component 60, as well as of the junction surface of the outer core part 51 and the non-magnetic component 60, can be prevented. Fifth embodiment

[0090] In the first embodiment described above, the depth of the groove 61 is set smaller than the depth of the inner weld part W20 and the depth of the outer weld part W10. On the other hand, in the present embodiment, which is described in Fig. As shown in Figure 9, the depth of the groove 61 is adjusted such that it is greater than the depth of the inner weld part W20 and the depth of the outer weld part W10. This improves the reliability of preventing contact between the inner weld part W20 and the outer weld part W10, and also improves the reliability of preventing magnetic short circuits. Sixth embodiment

[0091] In the first embodiment described above, the cross-sectional shape of the groove 61 is a quadrilateral. On the other hand, in the present embodiment, which is described in Fig. Figure 10 shows a shape which combines two quadrilaterals, and this is a shape in which the width dimension, namely the dimension in the left-right direction, is Fig. 10, reduced, as it moves away from the weld surface 60b. The present embodiment, in which the cross-sectional shape of the groove 61 is thus made into a square with a step, also produces effects similar to those of the first embodiment described above. Seventh embodiment

[0092] In the sixth embodiment described above, the cross-sectional shape of the groove 61 is made into a quadrilateral with a step. On the other hand, in the present embodiment, the cross-sectional shape of the groove 61 is made into a triangle, as shown in Fig. Figure 11 is shown. The present embodiment also produces effects similar to those of the first embodiment described above. Furthermore, the cross-sectional shape of the groove 61 in the present disclosure is not limited to a rectangular shape, as in the first embodiment described above, a rectangular shape with a step, as in the sixth embodiment described above, or a triangle, as in the present embodiment. Eighth embodiment

[0093] Although the inner tapered surface 52f and the outer tapered surface 51f, which are arranged inclined in the same direction, are in the first embodiment described above (compare Fig. 1) are manufactured in such a way that they are arranged inclined in a direction such that the dimension in the radial direction becomes smaller as it approaches the side of the injection hole in the axial direction, the direction of inclination in the present embodiment (compare Fig. 12) Conversely. The technical meaning will be explained below.

[0094] In the first embodiment described above, the force of the fuel pressure applied to the solid core 50 is absorbed by the preload generated by the axial force F10 and the fastening component 81. Furthermore, a portion of the axial force F11 is dispersed as a compressive component through both of the tapered surfaces, and the shear component applied to the joint surface is reduced to prevent fracture of the joint surface due to the axial force F11. To achieve this effect, both of the tapered surfaces are inclined in such a direction that the dimension decreases in the radial direction as it approaches the side of the injection hole.

[0095] On the other hand, in the present embodiment, part of the axial force, the compressive component, is dispersed through both of the tapered surfaces, and the shear component applied to the joint surface is reduced to prevent fracture of the joint surface by a force of fuel pressure applied to the solid core 50. To achieve such an action, both of the tapered surfaces are manufactured such that they are inclined in a direction opposite to that of Fig. 1 runs in such a direction that the dimension in the radial direction becomes larger as it approaches the side of the injection hole (compare Fig. 12).

[0096] Furthermore, in the first embodiment described above, the axial force F10 is generated by screwing the mounting component 81 to the housing 10, and the non-magnetic component 60 is sandwiched between the two tapered surfaces by the axial force F10. In contrast, in the present embodiment, the mounting component 81 and the housing 10 are eliminated, a mounting component 810 is attached to the nozzle body 20, and the non-magnetic component 60 is sandwiched between the two tapered surfaces by the axial force generated by the mounting force.

[0097] More precisely, the mounting component 810 has a circular cylindrical shape and is attached to the nozzle body 20 by engaging a threaded section 810n, formed on the inner circumferential surface of the mounting component 810, with a threaded section 21n, formed on the outer circumferential surface of the main part 21. A pressure surface 510c is formed on a surface opposite the injection hole of an outer core part 510, to which the mounting component 810 abuts. The pressure surface 510c is positioned on the outer side in the radial direction of the cap part 53 and is formed in an annular shape extending perpendicular to the axial direction.

[0098] In a state where the fuel injector is not yet in use, an axial force, generated by screwing in the mounting component 810, is applied to the pressure surface 510c. A reaction force opposing this axial force is applied to the outer core part 510, originating from the upper end surface 21b of the body part 21. The outer core part 510 is thereby sandwiched between the body part 21 and the mounting component 810, and movement towards the opposite side of the injection hole in the axial direction is restricted.

[0099] In an operating state of the fuel injector, a reaction force opposing the internal fuel pressure boost force is applied from the mounting component 810 to the pressure surface 510c. This means that the boost force of the internal fuel pressure is transmitted to the mounting component 810 via an inner tapered surface 520f, the non-magnetic component 60, an outer tapered surface 510f, and the pressure surface 510c. A force transmitted from the internal fuel pressure boost force to the inner tapered surface 520f is divided into a compressive component, which runs perpendicular to the inner tapered surface 520f, and a shear component, which runs parallel to the inner tapered surface 520f.A force transmitted to the outer tapered surface 510f is subdivided, starting from a reaction force applied by the fastening component 810 against the inner fuel pressure boost force, into a compressive component that runs perpendicular to the outer tapered surface 510f and a shear component that runs parallel to the outer tapered surface 510f.

[0100] In the present embodiment, outside an inner core part 520 and an outer core part 510, there is a core part in which the pressure-absorbing surface, which receives the pressure of the fuel from the side of the movable core 40, is large. The inner core part 520 is equivalent to a large pressure-absorbing core part, and the outer core part 510 is equivalent to a small pressure-absorbing core part. The fastening component 810 is equivalent to an outer mounting component, which applies the reaction force against a force that is absorbed by the large pressure-absorbing core part, originating from the pressure-absorbing surface (inner fuel pressure boost force) towards the small pressure-absorbing core part.

[0101] Furthermore, the inner tapered surface 520f and the outer tapered surface 510f are inclined in such a direction that the non-magnetic component 60 is sandwiched in place by the force absorbed by the large pressure-receiving core element emanating from the pressure-receiving surface (inner fuel pressure boost force) and a reaction force emanating from the mounting component 810. More precisely, both tapered surfaces are inclined in such a direction that the dimension increases in the radial direction as it approaches the side of the injection hole.

[0102] Based on the foregoing, in the present embodiment the connection surface against the non-magnetic component 60 outside the inner core part 520 is produced in such a way that it has a tapered shape, and the connection surface against the non-magnetic component 60 outside the outer core part 510 is produced in such a way that it has a tapered shape.

[0103] Furthermore, these connecting surfaces, namely the inner tapered surface 520f and the outer tapered surface 510f, are arranged inclined in the same direction with respect to the annular center line C, and more precisely, they are arranged inclined in the direction in which the non-magnetic component 60 is sandwiched in by the inner fuel pressure boost force and the reaction force, the reaction force being caused by the fastening component 810.

[0104] Therefore, such an event can be avoided by ensuring that the entire boost force, originating from the internal fuel pressure boost force and transferred to the internal tapered surface 520f, is applied to the internal tapered surface 520f as a shear force. That is, the boost force is dispersed into a compressive component and a shear component, and the shear component is reduced by a portion of the compressive component. Similarly, a reaction force transferred to the external tapered surface 510f is dispersed into a compressive component and a shear component, and the shear component is reduced by a portion of the compressive component.Accordingly, a problem of fracture of the connection surface due to the internal fuel pressure boost force can be prevented, as the shear force applied to the inner tapered surface 520f and the outer tapered surface 510f can be reduced.

[0105] Although the embodiments have been explained above, the present disclosure is by no means limited to the embodiments described above and can be implemented in various modifications, as exemplified below. It is possible not only to combine sections where it is explicitly stated that a combination is expressly possible for each embodiment, but also to partially combine the embodiments, even if the combination is not explicitly stated, as long as the combination does not cause any particular problem. Modifications of the embodiments described above will be described.

[0106] In the embodiment described above, the shape of the recess described above is not limited to the shape of the groove 61, and the recess described above can, for example, be a cutout, although the recess formed on a section between the inner weld part W20 and the outer weld part W10, starting from the weld surface 60b, is made into the groove 61. Insofar as a space can be formed between the inner weld part W20 and the outer weld part W10, the recess can be suitably modified.

[0107] Furthermore, the recess and groove 61 described above can be arranged over the entire circumference of the weld surface 60b or only partially. If the recess and groove 61 described above are arranged over the entire circumference, the event of the inner weld part W20 and the outer weld part W10 coming into contact with each other can be prevented more reliably.

[0108] Although the interior of groove 61 is an empty space in each embodiment described above, it can be filled with a component made of resin or the like. However, the component to be filled should be non-magnetic.

[0109] Although the outer weld part W10, the inner weld part W20 and the groove 61 are formed on a selected end surface on the side of the injection hole and the end surface on the opposite side of the injection hole of the non-magnetic component 60 in each embodiment described above, the outer weld part W10, the inner weld part W20 and the groove 61 can be formed on both the end surface on the side of the injection hole and the end surface on the opposite side of the injection hole.

[0110] In a first embodiment described above, the outer tapered surface 51f and the inner tapered surface 52f are formed over the entire surface of a surface which connects with the non-magnetic component 60 in the cross-section which includes the annular center line C.

[0111] On the other hand, at least one selected from the outer tapered surface 51f and the inner tapered surface 52f can be formed in a part of a surface which connects with the non-magnetic component 60 in the cross-section which includes the annular center line C.

[0112] In the first embodiment described above, the interface between the solid core 50 and the non-magnetic component 60 is formed in a tapered shape in the cross-section containing the annular center line C. Alternatively, the interface described above can be formed in a stepped shape as explained below. That is, at least in a portion of a surface that connects with the non-magnetic component 60 outside the inner core part 52, an inner perpendicular surface is formed, which extends perpendicular to the axial direction in the cross-section containing the annular center line C.Furthermore, at least in part of a surface that connects with the non-magnetic component 60 outside the outer core part 51, an outer perpendicular surface is formed which extends perpendicular to the axial direction in the cross-section which includes the annular center line C.

[0113] Furthermore, the connecting surface of the other core part can be formed in a tapered shape, similar to that of the first embodiment described above, while the connecting surface of a core part outside the outer core part 51 and the inner core part 52 is formed in a step shape.

[0114] In each embodiment described above, the annular outer circumferential surface of the coil 70, in the cross-section which includes the annular center line C, is positioned on the outer side in the radial direction of the outer circumferential surface of the movable core 40. Alternatively, the annular outer circumferential surface of the coil 70, with respect to its position in the radial direction, can be the same as the outer circumferential surface of the movable core 40 and can be positioned on the inner side in the radial direction of the outer circumferential surface of the movable core 40.

[0115] In the eighth embodiment, which is in Fig. As shown in Figure 12, a core part has a large pressure-absorbing surface that absorbs the pressure of the fuel from the side of the movable core 40, outside the inner core part 520 and the outer core part 51. The inner core part 520 is the large pressure-absorbing core part. Alternatively, it is also possible to make the pressure-absorbing surface of the outer core part 51 larger compared to the inner core part 520, and to make the outer core part 51 the core part that absorbs the large pressure. In this case, it is necessary to make the inclination direction of the outer tapered surface 510f and the inner tapered surface 520f opposite to the direction shown in Figure 12. Fig. 9 is shown. In addition, it is necessary to apply the reaction force against a force that is absorbed by the outer core part 51, which is the large pressure-receiving core part, originating from the pressure-receiving surface (outer fuel pressure boost force) on the inner core part 520, which is the small pressure-receiving core part, by means of the fastening component 810 and the like.

[0116] The first embodiment, which in Fig. As shown in Figure 1, such a structure has the following features: the fastening component 81, which is equivalent to an inner mounting part, applies the axial force F10 in the direction in which the inner core part 52 is pressed towards the side of the injection hole, and the body part 21, which is equivalent to an outer mounting part, applies the reaction force F20 in the direction in which the outer core part 51 is pressed towards the opposite side of the injection hole. Alternatively, in such a structure, it is also possible for the inner mounting part to apply the axial force F10 in the direction in which the inner core part 52 is pressed towards the side of the injection hole, and for the outer mounting part to apply the reaction force F20 in the direction in which the outer core part 51 is pressed towards the opposite side of the injection hole.In this case, it is necessary to establish the inclination direction of the outer tapered surface 51f and the inner tapered surface 52f opposite to the direction shown in . Fig. 1 is shown.

[0117] In the embodiments described in the Fig. 5, Fig. 6, Fig. 7 and Fig. As shown in Figure 12, the connection surface of the outer core part 51 and the non-magnetic component 60, as well as the connection surface of the inner core part 52 and the non-magnetic component 60, are arranged inclined with respect to the axial direction. Alternatively, the connection surfaces described above can be designed parallel to the axial direction, as in the embodiments shown in the Fig. 8, Fig. 9, Fig. 10 and Fig. 11 will be shown.

[0118] Although the present disclosure has been described with reference to the associated embodiments, this should not be interpreted as limiting the disclosure to these embodiments and constructions. Rather, the present disclosure is intended to cover various modifications and equivalent arrangements. Furthermore, the various combinations and configurations, including those containing additional, fewer, or only a single element, are also included within the spirit and scope of the present disclosure.

Claims

[1] Fuel injector for injecting fuel through an injection hole (23a), comprising: a coil (70) which is arranged in a ring shape; a solid core (50) which forms a magnetic field when the coil (70) is excited; a movable core (40) which is provided on the side of the injection hole (23a) of the fixed core (50) in a direction of an annular center line (C) of the coil (70) and forms a magnetic field between the movable core (40) and the fixed core (50) when the coil (70) is excited such that it is attracted to the fixed core (50); a valve body (30) which is driven by the attracted movable core (40) in such a way that it opens or closes the injection hole (23a); an inner core part (52) which is part of the solid core (50) which is opposite the movable core (40); an outer core part (51) which is part of the solid core (50) which is opposite the movable core (40) and is located outside the inner core part (52) with respect to the annular center line (C); a non-magnetic component (60) that is arranged between the inner core part (52) and the outer core part (51) and has a weaker magnetism than the solid core (50); an inner weld part (W20) which is a weld part between the inner core part (52) and the non-magnetic component (60) and is provided on at least one side selected from the side of the movable core (40) of the non-magnetic component (60) and a side of the non-magnetic component (60) opposite the movable core (40); and an outer weld part (W10) which is a weld part between the outer core part (51) and the non-magnetic component (60) and is provided on a weld surface (60b) of the non-magnetic component (60) on the same side as the inner weld part (W20), wherein a recess (61) is formed on a part of the weld surface (60b) between the inner weld part (W20) and the outer weld part (W10). [2] Fuel injection valve according to claim 1, wherein at least one selected from the inner weld part (W20) and the outer weld part (W10) is exposed from a wall surface (61a, 61b, 61c) of the recess (61). [3] Fuel injector according to claim 1 or 2, wherein it is provided that: a weld depth dimension of the inner weld part (W20) starting from the weld surface (60b) is an inner weld depth; a weld depth dimension of the outer weld part (W10) starting from the weld surface (60b) is an outer weld depth; and a dimension from the weld surface (60b) to a ground surface (61a) of the depression (61) is a depression depth, The recess depth is smaller than the inner weld depth and the outer weld depth. [4] Fuel injector according to any one of claims 1 to 3, wherein: a surface of the solid core (50) which is opposite the movable core (40), is an attraction surface (52a, 51c) of the solid core; and at least one selected from the inner weld part (W20) and the outer weld part (W10) is located in the direction of the annular center line (C) on a side of the attraction surface (52a, 51c) of the solid core opposite the movable core (40). [5] Fuel injector according to any one of claims 1 to 4, wherein: at least a part of a surface of the inner core part (52) connected to the non-magnetic component (60) includes an inner tapered surface (52f) which is a surface arranged inclined with respect to the annular center line (C) on a section which includes the annular center line (C); at least a part of a surface of the outer core part (51) connected to the non-magnetic component (60) includes an outer tapered surface (51f) which is a surface inclined with respect to the annular center line (C) on the section which includes the annular center line (C); and the inner tapered surface (52f) and the outer tapered surface (51f) are shaped such that they are inclined in the same direction with respect to the annular center line (C). [6] Fuel injection valve according to any one of claims 1 to 5, further comprising a stopper (54) which is fixed to the inner core part (52) and restricts a displacement quantity of the valve body (30) in a direction in which the valve body (30) opens the injection hole (23a) by contact with the valve body (30), wherein a length of the inner core part (52) in an extension direction of the annular center line (C) is longer than a length of the outer core part (51) in the extension direction of the annular center line (C).

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