Fuel injector

Abstract

Fuel injector (100, 100b, 100c, 100d), comprising: a housing (20, 20d) having a cylindrical shape, wherein the housing has an injection hole (31, 31d) at one end in a longitudinal direction (Z) of the housing for injecting fuel; a solid core (60) which is fixed in the housing; a movable core (50) which is arranged between one end and the fixed core in such a way that the latter is movable along the longitudinal direction in the housing; a needle (40) that opens or closes the injection hole by moving along the longitudinal direction in the housing, just as the movable core moves; and a coil (70) configured to generate a magnetic field for moving the movable core, wherein the movable core has a large-diameter section (56) which is arranged facing the fixed core, and a small-diameter section (57) which is provided between one end and the large-diameter section, wherein the small-diameter section has an outer diameter which is smaller than the outer diameter of the large-diameter section. the housing has a first section (122) on which the small-diameter section is movably arranged, a second section (123) on which the large-diameter section is movably arranged, and a stepped section (125) provided between the first section and the second section in the housing, wherein the second section has an inner diameter that is larger than the inner diameter of the first section. an inner component (90, 90b, 90c, 90d) is arranged inside the housing, wherein the inner component has a flange section (92, 92b) that is in contact with the step section, wherein the inner component has a cylindrical shape such that a gap is formed between the inner component and the first section in a radial direction, intersecting the longitudinal direction, a damper chamber (25) that stores the fuel, is defined by an inner surface of the second section, the flange section, the small diameter section and the large diameter section in the housing, and an outer side surface of the large-diameter section slides on an inner side surface of the second section, and an outer side surface of the small-diameter section slides on an inner side surface of the inner component.

Description

Technical area

[0001] The present disclosure relates to a fuel injector. background

[0002] JP 2018-189 002 A describes a fuel injection valve with a damper chamber surrounded by a housing and a movable core. In the fuel injection valve, the pressure of a fuel in the damper chamber is changed by the movement of the movable core. Because the change in pressure decelerates the movable core, the impact due to collision between the movable core and the fixed core is reduced when the valve is open. Furthermore, the impact caused by collision between the needle and the valve seat is reduced when the valve is closed.

[0003] Further prior art is disclosed in DE 103 32 812 A1. Summary

[0004] In the fuel injection valve described above, the movable core has a large-diameter portion and a small-diameter portion that have different outer diameters. The large-diameter portion and the small-diameter portion slide on portions of the housing that differ in inner diameter. Since the portion on which the large-diameter portion slides and the portion on which the small-diameter portion slides are provided in a single component, it is difficult to manufacture them with high dimensional accuracy. If the actual clearance between the movable core and the housing becomes smaller than a set clearance, the sliding resistance between the movable core and the housing will increase. In the worst case, the movable core may be locked.be blocked and cannot move. If the set gap between the movable core and the housing is increased, the damper chamber's impact reduction effect may not be sufficiently exerted.

[0005] The present disclosure may be implemented as the following embodiments.

[0006] According to one aspect of the present disclosure, a fuel injection valve includes: a housing having a cylindrical shape, the housing having an injection hole for injecting fuel at one end in a longitudinal direction of the housing; a fixed core fixed in the housing; a movable core arranged between the one end and the fixed core so as to be movable along the longitudinal direction in the housing; a needle that opens or closes the injection hole by moving along the longitudinal direction in the housing as the movable core moves; and a coil configured to generate a magnetic field for moving the movable core.The movable core includes a large-diameter portion disposed facing the fixed core, and a small-diameter portion disposed between one end and the large-diameter portion and having an outer diameter smaller than an outer diameter of the large-diameter portion. The housing includes a first portion at which the small-diameter portion is movably disposed, a second portion at which the large-diameter portion is movably disposed and having an inner diameter larger than an inner diameter of the first portion, and a stepped portion provided between the first portion and the second portion in the housing.An inner member is arranged within the housing, the inner member having a flange portion in contact with the step portion, the inner member having a cylindrical shape such that a gap is formed between the inner member and the first portion in a radial direction intersecting the longitudinal direction. A damper chamber that stores the fuel is defined by an inner surface of the second portion, the flange portion, the small diameter portion, and the large diameter portion in the housing. An outer side surface of the large diameter portion slides on an inner side surface of the second portion, and an outer side surface of the small diameter portion slides on an inner side surface of the inner member.

[0007] Accordingly, since the housing on which the large-diameter portion of the movable core slides and the inner member on which the small-diameter portion of the movable core slides are configured as separate components, it becomes easy to process with high dimensional accuracy. Therefore, it becomes easy to provide a gap between the large-diameter portion and the housing, and a gap between the small-diameter portion and the inner member with the intended size. Thus, it is possible to restrict the movable core from being locked and thus unable to move, and it is possible to easily exert a sufficient impact reduction effect on the damper chamber. Short description of the drawings

[0008] It shows / it shows: Fig. 1 is a first explanatory diagram showing a schematic configuration of a fuel injection valve according to a first embodiment in a valve closing state; Fig. 2 an enlarged view of an area A in Fig. 1; Fig. 3 is a second explanatory diagram showing a schematic configuration of the fuel injection valve of the first embodiment in a valve opening state; Fig. 4 is an explanatory diagram showing a schematic configuration of a fuel injection valve according to a second embodiment; Fig. 5 is an explanatory diagram showing a schematic configuration of a fuel injection valve according to a third embodiment; Fig. 6 is an explanatory diagram showing a schematic configuration of a fuel injection valve according to a fourth embodiment; Fig. 7 an enlarged view of a surface B in Fig. 6; Description of the embodimentFirst embodiment:

[0009] As in Fig. 1, a fuel injection valve 100 according to a first embodiment includes a housing 20, a needle 40, a movable core 50, a fixed core 60, a coil 70, a first biasing member 81 and a second biasing member 82. In Fig. 1 shows arrows along the X, Y, and Z directions that are orthogonal to each other. In other figures, the arrows along the X, Y, and Z directions are also appropriately depicted. The X, Y, and Z directions in Fig. 1 and the X, Y, and Z directions in other figures each represent the same direction. The fuel injector 100 injects fuel. In this embodiment, the fuel injector 100 injects hydrogen gas, which is a gaseous fuel. The fuel injector 100 may inject a gaseous fuel such as coal gas, acetylene gas, propane gas, or natural gas instead of hydrogen gas. The fuel injector 100 may inject a liquid fuel such as gasoline or light oil instead of the gaseous fuel.

[0010] The housing 20 has a longitudinal direction along the Z direction. The housing 20 includes a first tubular member 21, a second tubular member 22, a third tubular member 23, and a fourth tubular member 24, which are connected in this order toward the +Z side in the Z direction. Each of the tubular members 21 to 24 has a cylindrical shape with the central axis CL along the Z direction. An injection hole 31 for injecting fuel is provided at the end of the first tubular member 21 in the -Z direction. A valve seat 32 is provided around the peripheral edge of the injection hole 31 of the first tubular member 21. A valve portion 42 of the needle 40 is to be in contact with the valve seat 32. In the present embodiment, the first tubular member 21 and the second tubular member 22 are fixed to each other by welding, press fitting or the like.The second tubular member 22 and the third tubular member 23 are fixed to each other by welding, press fitting, or the like. The third tubular member 23 and the fourth tubular member 24 are fixed to each other by welding, press fitting, or the like. The first tubular member 21 is made of martensitic stainless steel, which is a metallic material, and is hardened to a predetermined hardness. The second tubular member 22 and the fourth tubular member 24 are made of ferritic stainless steel, which is a magnetic material. The third tubular member 23 is made of austenitic stainless steel, which is a non-magnetic material.

[0011] An inner member 90 is housed in the first tubular member 21. The inner member 90 has a cylindrical shape along the Z direction with the central axis CL. In the present embodiment, the inner member 90 is housed in the first tubular member 21, so that a gap in the radial direction is formed between the inner member 90 and the first tubular member 21. As described later, the inner member 90 is fixed by being pressed against the first tubular member 21 in the -Z direction by the second biasing member 82. The inner member 90 is made of martensitic stainless steel, which is a metallic material, and is quenched to have a predetermined hardness. The specific structure of the inner member 90 will be described later.

[0012] A fuel introduction pipe 12 is connected to the fourth tubular member 24. In the present embodiment, the fourth tubular member 24 and the fuel introduction pipe 12 are fixed to each other by welding. The fuel introduction pipe 12 has a cylindrical shape with the central axis CL. An introduction port 14 for introducing fuel is provided at the end of the fuel introduction pipe 12 in the +Z direction. A supply pipe for supplying fuel to the fuel injection valve 100 is connected to the fuel introduction pipe 12. A filter 13 is provided in the fuel introduction pipe 12. The filter 13 collects foreign matter in the fuel flowing from the introduction port 14 and prevents foreign matter from flowing into the housing 20.

[0013] The needle 40 is arranged in the housing 20 so as to be movable along the central axis CL. The needle 40 includes a shaft portion 41, the valve portion 42, and an enlarged diameter portion 43. The shaft portion 41 has a cylindrical shape with the central axis CL. The valve portion 42 is provided at the end of the shaft portion 41 in the -Z direction. The injection hole 31 is closed by the valve portion 42 coming into contact with the valve seat 32, and the injection hole 31 is opened by the valve portion 42 being separated from the valve seat 32. The enlarged diameter portion 43 is provided at the end of the shaft portion 41 in the +Z direction. The outer diameter of the enlarged diameter portion 43 is larger than the outer diameter of the shaft portion 41.The enlarged diameter portion 43 contacts an end surface of the movable core 50 on the +Z side in the Z direction. A fuel passage 44 through which fuel flows along the center axis CL is provided within the shaft portion 41 and the enlarged diameter portion 43. The fuel passage 44 has an opening on the end surface of the enlarged diameter portion 43 in the +Z direction. A communication hole 45 communicating with the fuel passage 44 is provided in a side surface of the shaft portion 41.

[0014] The movable core 50 is arranged in the housing 20 so as to be movable along the central axis CL. The movable core 50 has a cylindrical shape with the central axis CL. The shaft portion 41 penetrates the inside of the movable core 50, and the shaft portion 41 slides on the inner wall surface of the movable core 50. Sliding not only means that one object slides on the surface of the other object while the two objects are in contact with each other, but also means that one object slides over the surface of the other object while fluid exists between one object and the other object that are arranged adjacent to each other. The movable core 50 has a large-diameter portion 56 and a small-diameter portion 57. The outer diameter of the large-diameter portion 56 is larger than the outer diameter of the small-diameter portion 57.The small-diameter portion 57 is provided to protrude from the large-diameter portion 56 in the -Z direction. The enlarged-diameter portion 43 contacts the end surface of the large-diameter portion 56 on the +Z side in the Z direction.

[0015] In the present embodiment, the movable core 50 is composed of a first movable core member 51 made of a magnetic material and a second movable core member 52 having a hardness higher than that of the first movable core member 51. The hardness of the first movable core member 51 and the hardness of the second movable core member 52 can be determined by a Vickers hardness test (JIS Z 2244). The main body of the movable core 50 is composed of the first movable core member 51. The second movable core member 52 of the movable core 50 slides on the housing 20, contacts the fixed core 60, slides on or contacts the needle 40, and contacts or slides on the inner member 90. In the present embodiment, the first movable core member 51 is made of ferritic stainless steel, which is a magnetic material.The second movable core member 52 is made of martensitic stainless steel, which is a metal material, and is quenched to have a predetermined hardness. The first movable core member 51 and the second movable core member 52 are fixed to each other by press fitting, welding, or the like.

[0016] The fixed core 60 is fixed to the +Z side of the movable core 50 in the housing 20. In the present embodiment, the fixed core 60 is fixed to the fourth tubular member 24 by welding or the like. The fixed core 60 has a cylindrical shape with the central axis CL. The enlarged diameter portion 43 of the needle 40 slides on the inner wall surface of the fixed core 60. The movable core 50, moving along the central axis CL, contacts the end surface of the fixed core 60 in the -Z direction. An adjusting tube 11 having a cylindrical shape with the central axis CL is press-fitted to an inner portion of the fixed core 60 on the +Z side.

[0017] In the present embodiment, the fixed core 60 is composed of a first fixed core member 61 made of a magnetic material and a second fixed core member 62 having a hardness higher than that of the first fixed core member 61. The hardness of the first fixed core member 61 and the hardness of the second fixed core member 62 can be determined by a Vickers hardness test (JIS Z 2244). The main body of the fixed core 60, which faces the first movable core member 51, is configured by the first fixed core member 61. The enlarged diameter portion 43 slides on the second fixed core member 62 of the fixed core 60. The movable core 50 contacts the second fixed core member 62 of the fixed core 60 from the -Z side in the Z direction.In the present embodiment, the fixed core is configured such that an end surface of the second fixed core member 62 protrudes in the -Z direction by several tens of micrometers from an end surface of the first fixed core member 61 in the -Z direction. When the movable core 50 comes into contact with the fixed core 60, the second movable core member 52 comes into contact with the second fixed core member 62, and a gap is provided between the first fixed core member 61 and the first movable core member 51. In the present embodiment, the first fixed core member 61 is made of ferritic stainless steel, which is a magnetic material. The second fixed core member 62 is made of martensitic stainless steel, which is a metallic material, and is quenched to have a predetermined hardness.The first fixed core member 61 and the second fixed core member 62 are fixed to each other by press fitting. The fixed core 60 may be configured such that the end surface of the first fixed core member 61 in the -Z direction is flush with the end surface of the second fixed core member 62 in the -Z direction. In this case, the movable core 50 is configured such that the end surface of the second movable core member 52 in the +Z direction protrudes by several tens of micrometers in the +Z direction from the end surface of the first movable core member 51 in the +Z direction.

[0018] The first biasing member 81 is arranged between the adjusting tube 11 and the enlarged diameter portion 43 within the fixed core 60. The first biasing member 81 biases the needle 40 in the -Z direction. In the present embodiment, the first biasing member 81 is composed of a coil spring that expands or contracts along the Z direction. One end of the first biasing member 81 on the +Z side is in contact with the adjusting tube 11, and one end of the first biasing member 81 on the -Z side is in contact with the enlarged diameter portion 43. The force with which the first biasing member 81 biases the needle 40 can be adjusted by adjusting the position of the adjusting tube 11 in the Z direction. In the present embodiment, the position of the adjusting tube 11 is adjusted in such a way.adapted that the force of the first biasing member 81 for biasing the needle 40 is greater than the force of the second biasing member 82, which will be described later, for biasing the movable core 50.

[0019] The second biasing member 82 is arranged between the inner member 90 and the small-diameter portion 57. The second biasing member 82 biases the movable core 50 in the +Z direction. In the present embodiment, the second biasing member 82 is composed of a coil spring that expands or contracts along the Z direction. One end of the second biasing member 82 in the -Z direction contacts a bottom surface portion 93 of the inner member 90, and the other end of the second biasing member 82 in the +Z direction contacts the small-diameter portion 57.

[0020] A coil bobbin 71, around which the coil 70 is wound, is arranged on the outer wall surface of the housing 20. In the present embodiment, the coil bobbin 71 is arranged over the outer wall surface of the third tubular member 23 and the outer wall surface of the fourth tubular member 24. A portion of the outer wall surface of the fourth tubular member 24, on which the coil bobbin 71 is not arranged, and a portion of the outer wall surface of the fuel introduction pipe 12 are covered with a resin material. A connector 15 is provided on the fourth tubular member 24 side so as to protrude from the outer wall surface of the fourth tubular member 24. The connector 15 has a terminal 16 that is electrically connected to the coil 70.In this embodiment, the connector 15, made of resin, is provided with the terminal 16, which is made of metal by insert molding. A power source such as a battery is electrically connected to the terminal 16 via a switching element or the like.

[0021] The coil 70 generates a magnetic field by supplying it with an electric current from a power source. The magnetic field generated by the coil 70 forms a magnetic circuit that passes through the second tubular member 22, the first fixed core member 61, the first movable core member 51, and the fourth tubular member 24. Therefore, a magnetic attraction force is generated between the movable core 50 and the fixed core 60. A cylindrical holder 17 is provided on the outer periphery of the coil 70 so as to cover the coil 70. An annular cover 18 is provided between the fourth tubular member 24 and the holder 17. Both the holder 17 and the cover 18 are made of a magnetic material and form part of the magnetic circuit described above.

[0022] As in Fig. 2, the housing 20 includes, in order from the -Z side in the Z direction, a first inner side surface 121 that houses the shaft portion 41, a second inner side surface 122 that houses the inner member 90, and a third inner side surface 123 on which the large-diameter portion 56 slides. Each of the first inner side surface 121, the second inner side surface 122, and the third inner side surface 123 has a cylindrical shape with the central axis CL. The inner diameter of the second inner side surface 122 is larger than the inner diameter of the first inner side surface 121. The inner diameter of the third inner side surface 123 is larger than the inner diameter of the second inner side surface 122. A first step surface 124 connects the first inner side surface 121 and the second inner side surface 122.The second inner side surface 122 and the third inner side surface 123 are connected by a second step surface 125. Both the first step surface 124 and the second step surface 125 have an annular shape with the central axis CL. A portion of the housing 20 provided with the second inner side surface 122 may be referred to as a first portion. A portion of the housing 20 provided with the third inner side surface 123 may be referred to as a second portion. A portion of the housing 20 provided with the second step surface 125 may be referred to as a step portion.

[0023] The inner member 90 includes a tubular portion 91, a flange portion 92, and a bottom surface portion 93. The tubular portion 91 has a cylindrical shape with the central axis CL. A fourth inner side surface 191, on which the small-diameter portion 57 slides, is provided on the inner wall surface of the tubular portion 91. The flange portion 92 is provided along the second step surface 125 and protrudes outward from the +Z side end of the tubular portion 91 in the radial direction of the tubular portion 91. The bottom surface portion 93 is provided along the first step surface 124 and protrudes inward from the -Z side end of the tubular portion 91 in the radial direction of the tubular portion 91.Each of the flange portion 92 and the bottom surface portion 93 has an annular shape with the central axis CL. The outer diameter of the flange portion 92 is smaller than the inner diameter of the third inner side surface 123. The outer diameter of the tubular portion 91 is smaller than the inner diameter of the second inner side surface 122. The inner diameter of the bottom surface portion 93 is larger than the outer diameter of the shaft portion 41. Therefore, a gap having a predetermined width in the radial direction is provided between the flange portion 92 and the third inner side surface 123. A gap having a predetermined width in the radial direction is provided between the tubular portion 91 and the second inner side surface 122.A gap having a predetermined width in the radial direction is provided between the bottom surface portion 93 and the shaft portion 41. Further, a gap having a predetermined width in the Z direction is provided between the bottom surface portion 93 and the first step surface 124. As described above, the second biasing member 82 is provided between the bottom surface portion 93 and the small-diameter portion 57, and the inner member 90 is biased in the -Z direction by the second biasing member 82. Therefore, the flange portion 92 is pressed against the second step surface 125 in the -Z direction, and the sealing property between the flange portion 92 and the second step surface 125 is ensured.

[0024] A damper chamber 25 is surrounded by the third inner side surface 123, the second step surface 125, the flange portion 92, the small-diameter portion 57, and the large-diameter portion 56 provided inside the housing 20. Fuel is stored in the damper chamber 25. The fuel is not completely sealed in the damper chamber 25, but the flow of fuel is restricted to such an extent that the fuel cannot freely flow into or out of the damper chamber 25. The inside of the damper chamber 25 communicates with the outside of the damper chamber 25 through a gap between the third inner side surface 123 and the large-diameter portion 56, and a gap between the fourth inner side surface 191 and the small-diameter portion 57.In the present embodiment, the housing 20, the movable core 50, and the inner member 90 are provided such that both the gap between the third inner side surface 123 and the large-diameter portion 56 and the gap between the fourth inner side surface 191 and the small-diameter portion 57 have a dimension ranging from several micrometers to several tens of micrometers. Thus, the free entry and exit of fuel is restricted.

[0025] The valve opening operation for switching the fuel injection valve 100 from the valve closing state shown in Fig. 1, to the valve opening state shown in Fig. 3. As shown in Fig. 1, the injection hole 31 is closed in the valve-closing state because the valve portion 42 is in contact with the valve seat 32. In the valve-closing state, no current is supplied to the coil 70. The needle 40 is biased in the -Z direction by the first biasing member 81, and the movable core 50 is biased in the +Z direction by the second biasing member 82. Therefore, the needle 40 and the movable core 50 are stationary, while the enlarged diameter portion 43 of the needle 40 and the large diameter portion 56 of the movable core 50 are in contact with each other. A gap is provided between the movable core 50 and the fixed core 60 so that the movable core 50 can move during the valve-opening operation.The fuel flowing in from the introduction port 14 flows in the order of the fuel introduction pipe 12, the inside of the fixed core 60, the fuel passage 44, and the connecting hole 45, and is guided to the injection hole 31. Part of the fuel flowing in from the introduction port 14 flows into the damper chamber 25 through the gap between the third inner side surface 123 and the large-diameter portion 56 and the gap between the fourth inner side surface 191 and the small-diameter portion 57. Therefore, the damper chamber 25 is filled with fuel.

[0026] When the current supply to the coil 70 is started, a magnetic attraction force is generated between the first fixed core member 61 of the fixed core 60 and the first movable core member 51 of the movable core 50, and the movable core 50 is moved in the +Z direction toward the fixed core 60. The needle 40 is moved together with the movable core 50 because the enlarged diameter portion 43 is pressed by the large diameter portion 56. The movement of the needle 40 causes the valve portion 42 to separate from the valve seat 32, and fuel injection from the injection hole 31 is started.

[0027] The volume of the damper chamber 25 increases or expands as the movable core 50 moves in the +Z direction, so that the pressure of fuel in the damper chamber 25 decreases. Therefore, a force that decelerates the movable core 50 and the needle 40 acts on the movable core 50. When the second movable core member 52 of the movable core 50 collides with the second fixed core member 62 of the fixed core 60, the movement of the movable core 50 is stopped. In other words, the fixed core 60 restricts the movement of the movable core 50 in the +Z direction. Since the movable core 50 is decelerated by the damper chamber 25, the impact force is reduced when the second movable core member 52 of the movable core 50 collides with the second fixed core member 62 of the fixed core 60.

[0028] After the movable core 50 collides with the fixed core 60, the needle 40 continues to move in the +Z direction by inertia independently of the movable core 50. Elastic energy is stored in the first biasing member 81 by the first biasing member 81 being pressed by the enlarged diameter portion 43 and contracting in accordance with the movement of the needle 40. Thereafter, the needle 40 is pushed back toward the movable core 50 in the -Z direction by the elastic energy stored in the first biasing member 81. When the enlarged diameter portion 43 collides with the large diameter portion 56, the movement of the needle 40 is stopped.As described above, since the needle 40 and the movable core 50 are decelerated by the damper chamber 25, the impact force when the second movable core member 52 collides with the second fixed core member 62 is reduced. Furthermore, since the needle 40 is decelerated by the damper chamber 25 when the needle 40 moves together with the movable core 50, the elastic energy stored in the first biasing member 81 is reduced. Therefore, the impact force when the enlarged diameter portion 43 collides with the large diameter portion 56 is reduced. After the movement of the movable core 50 is stopped, the fuel flows into the damper chamber 25 through, for example, the gap between the third inner side surface 123 and the large diameter portion 56.Through the series of operations described above, the fuel injection valve 100 is brought into the valve opening state shown in . Fig. 3. In the valve-opening state, a predetermined amount of fuel is injected from the injection hole 31. The fuel injection valve 100 is kept open while the current supply to the coil 70 continues.

[0029] A valve closing operation for switching the fuel injection valve 100 from the valve opening state shown in Fig. 3, to the valve closing state shown in Fig. 1. The magnetic attraction force between the first fixed core member 61 and the first movable core member 51 disappears by stopping the supply of electric current to the coil 70. Therefore, the needle 40 is urged by the first biasing member 81 to move in the -Z direction. When the large-diameter portion 56 of the movable core 50 is urged by the enlarged-diameter portion 43 of the needle 40, the movable core 50 moves together with the needle 40 in the -Z direction.

[0030] The volume of the damper chamber 25 is reduced in accordance with the movement of the movable core 50 in the -Z direction, so that the pressure of the fuel in the damper chamber 25 increases. Therefore, a force that decelerates the movable core 50 and the needle 40 acts on the movable core 50. When the pressure of the fuel in the damper chamber 25 increases, the fuel in the damper chamber 25 gradually flows out of the damper chamber 25 via, for example, the gap between the third inner side surface 123 and the large-diameter portion 56. When the valve portion 42 collides with the valve seat 32, the movement of the needle 40 is stopped. In other words, the valve seat 32 restricts the movement of the needle 40 in the -Z direction. Since the needle 40 is decelerated by the damper chamber 25, the impact force when the valve portion 42 collides with the valve seat 32 is reduced.Since the injection hole 31 is closed by the valve portion 42 coming into contact with the valve seat 32, the injection of fuel from the injection hole 31 is stopped.

[0031] After the needle 40 collides with the valve seat 32, the movable core 50 continues to move in the -Z direction by inertia independently of the needle 40. Since the volume of the damper chamber 25 is further reduced by the movement of the movable core 50, a force for decelerating the movable core 50 acts on the movable core 50. As the second biasing member 82 is pressed by the movable core 50 to contract in accordance with the movement of the movable core 50, elastic energy is stored in the second biasing member 82. Thereafter, the movable core 50 is pushed back in the +Z direction by the elastic energy stored in the second biasing member 82. The movement of the movable core 50 is stopped by the large-diameter portion 56 contacting the enlarged-diameter portion 43.Since the movable core 50 is decelerated by the damper chamber 25, the elastic energy stored in the second biasing member 82 is reduced. Therefore, the impact when the large-diameter portion 56 contacts the enlarged-diameter portion 43 is reduced. Through the series of operations described above, the fuel injection valve 100 is placed in the valve-closing state shown in FIG. Fig. 1. In the valve closing state, fuel injection from the injection hole 31 is stopped.

[0032] According to the fuel injection valve 100 of the present embodiment, the fuel flows into and out of the damper chamber 25 through the gap between the third inner side surface 123 and the large-diameter portion 56 and the gap between the fourth inner side surface 191 and the small-diameter portion 57, and the damper chamber 25 reduces the impact at the time the valve is opened or closed. The third inner side surface 123, on which the large-diameter portion 56 slides, is provided on the housing 20, and the fourth inner side surface 191, on which the small-diameter portion 57 slides, is provided on the inner member 90, which is a member different from the housing 20.Therefore, compared with the case where the third inner side surface 123 and the fourth inner side surface 191 are provided on the same component, it is easier to process the third inner side surface 123 and the fourth inner side surface 191 with high dimensional accuracy. Thus, it is easy to provide the gap between the large-diameter portion 56 and the third inner side surface 123, as well as the gap between the small-diameter portion 57 and the fourth inner side surface 191, with the intended size. Accordingly, it is possible to restrict the movable core 50 from being locked, and it is possible to easily sufficiently exert the impact reduction effect of the damper chamber 25.

[0033] In the present embodiment, the fuel injection valve 100 injects hydrogen gas, which is a gaseous fuel. Since the viscosity of the gaseous fuel is lower than that of the liquid fuel, the impact at the time the valve is opened / closed is likely to be large. Therefore, due to the impact reducing effect of the damper chamber 25, it is possible to effectively suppress wear, failure, and the like. Furthermore, in the present embodiment, the gap between the third inner side surface 123 and the large-diameter portion 56, as well as the gap between the fourth inner side surface 191 and the small-diameter portion 57, can be processed more precisely. Therefore, the impact reducing effect of the damper chamber 25 can be enhanced.In addition, since the volume of the damper chamber 25 can be adjusted by adjusting the thickness of the flange portion 92, the impact reduction effect of the damper chamber 25 can be easily adjusted. Therefore, it is possible to suppress variations in the impact reduction effect between the fuel injection valves 100. Second embodiment

[0034] As in Fig. As shown in Fig. 4, the fuel injection valve 100b of the second embodiment differs from that of the first embodiment in the shape of the flange portion 92b of the inner member 90b. Other configurations and valve opening / closing operations are the same as those of the first embodiment unless otherwise specified.

[0035] The flange portion 92b includes an inner peripheral portion 94 provided in the radial direction on the outer periphery of the tubular portion 91, and an outer peripheral portion 95 provided in the radial direction on the outer periphery of the inner peripheral portion 94. The inner peripheral portion 94 contacts the second step surface 125, and a gap is provided between the outer peripheral portion 95 and the second step surface 125. In the present embodiment, the surface of the flange portion 92b on the +Z side is flat, and a step is provided on the surface of the flange portion 92b on the -Z side, thus defining the inner peripheral portion 94 and the outer peripheral portion 95. The thickness t2 of the outer peripheral portion 95 is smaller than the thickness t1 of the inner peripheral portion 94.

[0036] Fuel flows from the damper chamber 25 into the gap between the outer peripheral portion 95 and the second step surface 125. Because the inner peripheral portion 94 contacts the second step surface 125, the inflow of fuel from the damper chamber 25 is restricted between the inner peripheral portion 94 and the second step surface 125. The pressure of the fuel flowing into the gap between the outer peripheral portion 95 and the second step surface 125 is the same as the pressure of the fuel in the damper chamber 25.Therefore, the force received by the surface of the outer peripheral portion 95 on the +Z side along the Z direction from the fuel in the damper chamber 25 is balanced with the force received by the surface of the outer peripheral portion 95 on the -Z side along the Z direction from the fuel flowing into the gap between the outer peripheral portion 95 and the second step surface 125. When the pressure of the fuel in the damper chamber 25 increases, the inner peripheral portion 94 receives a force in the -Z direction. The bottom surface portion 93 receives a force from the second biasing member 82 in the -Z direction. Therefore, the inner peripheral portion 94 is pressed against the second step surface 125. When the pressure of the fuel in the damper chamber 25 decreases, the inner peripheral portion 94 receives a force in the +Z direction.The bottom surface portion 93 receives a force from the second biasing member 82 in the -Z direction. The outer peripheral portion 95 is provided to have a predetermined area such that the force exerted by the second biasing member 82 in the -Z direction on the bottom surface portion 93 is greater than the force exerted by the second biasing member 82 in the +Z direction on the inner peripheral portion 94 due to the pressure change of the fuel in the damper chamber 25. Therefore, the inner peripheral portion 94 is pressed against the second step surface 125 even if the pressure of the fuel in the damper chamber 25 decreases.

[0037] According to the fuel injection valve 100b, the flange portion 92b includes the inner peripheral portion 94 contacting the second step surface 125 and the outer peripheral portion 95 disposed separately from the second step surface 125. Therefore, the displacement of the inner member 90b with respect to the housing 20 in the +Z direction is suppressed when the pressure of the fuel within the damper chamber 25 decreases. Therefore, it is possible to suppress deterioration of the sealing property between the inner peripheral portion 94 and the second step surface 125, and it is possible to suppress deterioration of the impact reduction effect of the damper chamber 25. Third embodiment

[0038] As in Fig. As shown in Fig. 5, the fuel injection valve 100c of the third embodiment differs from the first embodiment in that an elastic sealing member 97 is provided between the tubular portion 91 of the inner member 90c and the second inner side surface 122 of the housing 20. Other configurations and valve opening / closing operations are the same as those of the first embodiment unless otherwise specified.

[0039] The elastic sealing member 97 is composed of a rubber O-ring. The elastic sealing member 97 is fitted into a groove portion 96 provided on the outer wall surface of the tubular portion 91. The elastic sealing member 97 is arranged to be pressed in the radial direction by the tubular portion 91 and the second inner side surface 122. Therefore, the elastic sealing member 97 enhances the sealing property between the tubular portion 91 and the second inner side surface 122. When the fuel flows in the gap between the tubular portion 91 and the second inner side surface 122, the elastic sealing member 97 is pressed in the Z direction by the pressure of the fuel to expand in the radial direction. Thus, the sealing property between the tubular portion 91 and the second inner side surface 122 is further enhanced.The groove portion may be provided on the second inner side surface 122 instead of the tubular portion 91, and the elastic sealing member 97 may be fitted into the groove portion provided on the second inner side surface 122.

[0040] According to the fuel injection valve 100c, not only is the sealing property of the damper chamber 25 improved by the elastic sealing member 97, but also the displacement of the inner member 90c in the +Z direction with respect to the housing 20 is suppressed by the frictional force of the elastic sealing member 97 while reducing the fuel pressure in the damper chamber 25. Therefore, it is possible to suppress deterioration of the sealing property between the flange portion 92 and the second step surface 125, and it is possible to suppress deterioration of the impact reduction effect of the damper chamber 25. Fourth embodiment

[0041] As in Fig. As shown in Fig. 6, the fuel injection valve 100d of the fourth embodiment differs from the first embodiment in that a third biasing member 83 is arranged between the housing 20d and the inner member 90d. Other configurations and valve opening / closing operations are the same as those of the first embodiment unless otherwise specified.

[0042] In the present embodiment, the housing 20d has an injection nozzle 30 at the end in the -Z direction. The injection nozzle 30 is fixed to the first tubular member 21d by press fitting, welding, or the like. The injection hole 31d and the valve seat 32d are provided in the injection nozzle 30 instead of in the first tubular member 21d. In this embodiment, the injection nozzle 30 is made of martensitic stainless steel, which is a metallic material, and is quenched to have a predetermined hardness.

[0043] As in Fig.As shown in Figure 7, the housing 20d has a fifth inner side surface 126 located on the -Z side of the first inner side surface 121 in the Z direction. The fifth inner side surface 126 has a cylindrical shape with the central axis CL. The inner diameter of the fifth inner side surface 126 is larger than the inner diameter of the first inner side surface 121. The fifth inner side surface 126 and the first inner side surface 121 are connected by a third step surface 127. The third step surface 127 has an annular shape with the central axis CL.

[0044] The inner member 90d has an extension portion 98 that protrudes in the -Z direction from the radially inner end of the bottom surface portion 93. The extension portion 98 extends from the bottom surface portion 93 into the fifth inner side surface 126. A preloaded portion 99 is provided at the end of the extension portion 98 in the -Z direction so as to protrude outward in the radial direction of the extension portion 98. In the present embodiment, the preloaded portion 99 is fixed to the extension portion 98 by press fitting or the like. Both the extension portion 98 and the preloaded portion 99 have a cylindrical shape with the central axis CL. The shaft portion 41 penetrates the inside of the extension portion 98 and the inside of the preloaded portion 99.

[0045] The third biasing member 83 is arranged between the third step surface 127 and the biased portion 99. The third biasing member 83 biases the biasing portion 99 in the -Z direction. In the present embodiment, the third biasing member 83 is composed of a coil spring that expands or contracts along the Z direction. The third biasing member 83 can be made of, for example, rubber or the like. The -Z direction end of the third biasing member 83 is in contact with the biased portion 99, and the +Z direction end of the third biasing member 83 is in contact with the third step surface 127.

[0046] According to the fuel injection valve 100d, the biased portion 99 fixed to the inner member 90d is biased in the -Z direction by the third biasing member 83, so that the flange portion 92 is pressed against the second step surface 125. Therefore, the displacement of the inner member 90d with respect to the housing 20d in the +Z direction is suppressed when the pressure of the fuel in the damper chamber 25 decreases. Therefore, it is possible to suppress deterioration of the sealing property between the flange portion 92 and the second step surface 125, and it is possible to suppress deterioration of the impact reduction effect of the damper chamber 25. Other embodiment

[0047] In the fuel injection valves 100 to 100c of the first to third embodiments, the first tubular member 21 of the housing 20 includes the injection hole 31 and the valve seat 32. In the fuel injection valve 100 to 100c, as in the fuel injection valve 100d of the fourth embodiment, the injection nozzle 30 may be fixed to the first tubular member 21, and the injection hole 31 and the valve seat 32 may be provided in the injection nozzle 30 instead of in the first tubular member 21.

[0048] In the fuel injection valve 100b of the second embodiment, the flange portion 92b of the inner member 90b has a step on the surface facing in the -Z direction so as to provide the inner peripheral portion 94 contacting the second step surface 125 and the outer peripheral portion 95 having a gap relative to the second step surface 125. In the fuel injection valve 100b, a step may be provided not in the flange portion 92b but in the second step surface 125. In this case, the inner peripheral portion 94 contacting the second step surface 125 and the outer peripheral portion 95 having a gap relative to the second step surface 125 are provided in the flange portion 92b.

[0049] In the fuel injection valve 100c of the third embodiment, the flange portion 92 of the inner member 90c may include the inner peripheral portion 94 in contact with the second step surface 125 and the outer peripheral portion 95 having a gap relative to the second step surface 125, as in the fuel injection valve 100b of the second embodiment. In this case, the positional displacement of the inner member 90c with respect to the housing 20 in the +Z direction can be more effectively suppressed.

[0050] In the fuel injection valve 100d of the fourth embodiment, the flange portion 92 of the inner member 90d may include the inner peripheral portion 94 in contact with the second step surface 125 and the outer peripheral portion 95 having a gap relative to the second step surface 125, as in the fuel injection valve 100b of the second embodiment. In this case, the positional displacement of the inner member 90d with respect to the housing 20d in the +Z direction can be more effectively suppressed. Furthermore, as in the fuel injection valve 100c of the third embodiment, an elastic sealing member 97 may be provided between the tubular portion 91 and the second inner side surface 122 of the housing 20d. In this case, the positional displacement of the inner member 90d with respect to the housing 20d in the +Z direction can be more effectively suppressed.

[0051] In the fuel injection valve 100 to 100d, the movable core 50 is composed of the first movable core member 51 and the second movable core member 52. However, the movable core 50 may also be composed of only the first movable core member 51.

[0052] In the fuel injection valve 100 to 100d, the fixed core 60, 60b is composed of the first fixed core component 61 and the second fixed core component 62. However, the fixed core 60, 60b may also be composed of only the first fixed core component 61.

[0053] The present disclosure should not be limited to the embodiments described above, but various other embodiments may be implemented without departing from the scope of the present disclosure. For example, the technical features in the embodiments may be replaced or combined where appropriate to solve some or all of the above problems or achieve some or all of the above effects. Furthermore, if the technical features are not described as essential in the present specification, they may be omitted where appropriate.

Claims

[1] Fuel injection valve (100, 100b, 100c, 100d), comprising: a housing (20, 20d) having a cylindrical shape, the housing having an injection hole (31, 31d) for injecting fuel at one end in a longitudinal direction (Z) of the housing; a fixed core (60) fixed in the housing; a movable core (50) arranged between said one end and said fixed core so as to be movable along the longitudinal direction in said housing; a needle (40) which opens or closes the injection hole by moving along the longitudinal direction in the housing as the movable core moves; and a coil (70) configured to generate a magnetic field for moving the movable core, wherein the movable core has a large-diameter portion (56) arranged facing the fixed core and a small-diameter portion (57) provided between one end and the large-diameter portion, the small-diameter portion having an outer diameter smaller than an outer diameter of the large-diameter portion, the housing has a first portion (122) on which the small diameter portion is movably arranged, a second portion (123) on which the large diameter portion is movably arranged, and a step portion (125) provided between the first portion and the second portion in the housing, wherein the second portion has an inner diameter that is larger than an inner diameter of the first portion, an inner member (90, 90b, 90c, 90d) is arranged within the housing, the inner member having a flange portion (92, 92b) in contact with the step portion, the inner member having a cylindrical shape such that a gap is formed between the inner member and the first portion in a radial direction, which gap intersects the longitudinal direction, a damper chamber (25) storing the fuel is defined by an inner surface of the second portion, the flange portion, the small diameter portion and the large diameter portion in the housing, and an outer side surface of the large diameter portion slides on an inner side surface of the second portion, and an outer side surface of the small diameter portion slides on an inner side surface of the inner member. [2] Fuel injection valve according to claim 1, wherein the flange portion has an inner peripheral portion (94) provided on an inner side in the radial direction and an outer peripheral portion (95) provided on an outer side of the inner peripheral portion in the radial direction, the inner peripheral portion is in contact with the step portion, and a gap is provided between the step portion and the outer peripheral portion. [3] A fuel injection valve according to claim 1 or 2, further comprising an elastic sealing member (97) disposed between the first portion and the inner member for sealing a space between the first portion and the inner member. [4] Fuel injection valve according to one of claims 1 to 3, further comprising: a prestressed portion (99) having a flange shape provided at an end portion of the inner member disposed facing the one end; and a prestressing member (83) for prestressing the prestressed portion toward said one end. [5] Fuel injection valve according to one of claims 1 to 4, wherein the fuel is a gaseous fuel. [6] Fuel injection valve according to one of claims 1 to 5, wherein the fuel is a hydrogen fuel.

Images