Gas fuel injection valve

Abstract

This fuel injection valve (10) comprises: a main body part (11) having a fuel passage (15) and an injection hole (17); an outward-opening needle valve (20) that closes the injection hole from the outside; a fixed core (31) fixed to the main body part; a movable core (32) that is attracted to the fixed core as a driving magnetic flux is generated, and that opens the needle valve against the biasing force of a biasing member; and a stopper (40) that is provided so that an axial end part on the tip side faces a position away from a nozzle, and that can reciprocate in the axial direction integrally with the needle valve. In the fuel injection valve, the stopper abuts against the nozzle before the movable core abuts against the fixed core after the movable core starts to move due to the driving magnetic flux, and the maximum lift amount of the needle valve is regulated by the abutment of the stopper.

Description

Gas fuel injection valve Cross-reference to related applications

[0001] This application is based on Japanese Application No. 2024-159196 filed on September 13, 2024 and Japanese Application No. 2025-77266 filed on May 7, 2025, the contents of which are incorporated herein by reference.

[0002] The disclosure in this specification relates to a gas fuel injection valve that injects gas fuel.

[0003] Conventionally, as a gas fuel injection valve that directly injects gas fuel into the combustion chamber of a gas engine, the technology described in Patent Document 1 is known. This gas fuel injection valve has an outward-opening valve structure, and biases the needle valve toward the closed valve side by the biasing force of a spring, and is configured to open the needle valve by a magnetic actuator. The magnetic actuator has a fixed core fixed to the main body of the gas fuel injection valve and a movable core that is displaced toward the side approaching the fixed core in the axial direction as the coil is energized. When the gas fuel injection valve is opened, the displacement of the movable core accompanying the coil energization lifts the needle valve from the closed valve position to the open valve position, and gas fuel is injected from the injection holes. In the gas fuel injection valve, a predetermined gap is provided between the fixed core and the movable core in the non-energized state of the coil, and the movable core is displaced until it hits the fixed core when the coil is energized. That is, the maximum lift amount of the needle valve is defined by the gap between the fixed core and the movable core.

[0004] German Patent Application Publication No. 102022204540

[0005] In the above configuration of a gas fuel injector, the maximum lift amount of the needle valve is determined by the gap between the fixed core and the movable core. In this case, if the axial length of the housing, which is the main body of the gas fuel injector, changes for any reason, the position of the fixed core changes in the axial direction, and as a result, an unintended change in the gap dimension between the fixed core and the movable core occurs. For example, if the axial length of the housing changes due to a change in the ambient temperature of the gas fuel injector, there is a concern that the gap dimension between the fixed core and the movable core will change as described above. Furthermore, if the gas fuel injector is tightened and fixed in the cylinder head of the engine with a predetermined axial force in the axial direction, it is conceivable that the gap dimension between the fixed core and the movable core may change due to variations in the tightening axial force of the gas fuel injector when it is assembled to the engine, or due to expansion and contraction due to temperature changes in the cylinder head. If the maximum lift amount of the needle valve changes due to a change in the gap dimension between the fixed core and the movable core, there is a concern that the gas fuel injection rate will vary, and consequently, the fuel injection amount will vary.

[0006] This disclosure is made in view of the above circumstances and aims to provide a technology that can suppress variations in injection volume in a gas fuel injection valve and enable proper fuel injection.

[0007] This disclosure relates to a gas fuel injection valve for injecting gaseous fuel, comprising: a main body that is cylindrical and has a fuel passage inside, and has a nozzle with a nozzle opening at its tip; an outward-opening needle valve provided within the main body and reciprocating in the axial direction, which closes the nozzle opening from the outside; a biasing member that biases the needle valve in the direction of closing the nozzle opening; a fixed core fixed to the main body; a movable core that is attracted to the fixed core in response to the generation of a driving magnetic flux, which causes the needle valve to open against the biasing force of the biasing member; and a stopper that is cylindrical and allows the needle valve to be inserted in the axial direction, which is reciprocating in the axial direction integrally with the needle valve, and which is provided such that its axial end on the tip side faces the nozzle at a position away from the nozzle, wherein after the movable core starts moving due to the driving magnetic flux, the stopper contacts the nozzle before the movable core contacts the fixed core, and the maximum lift amount of the needle valve is restricted by the contact of the stopper.

[0008] In the gas fuel injection valve with the above configuration, when the valve is opened, the movable core is attracted to the fixed core as a driving magnetic flux is generated, and at that time, the needle valve opens against the biasing force of the biasing member. The gas fuel injection valve has an outward-opening valve structure, and the injection port is opened when the needle valve moves to the outside of the main body. This starts fuel injection. In addition, in the above configuration, a cylindrical stopper is provided through which the needle valve is inserted in the axial direction and which is integral with the needle valve and can reciprocate in the axial direction, so that when the needle valve opens due to the generation of a driving magnetic flux, the stopper comes into contact with a nozzle provided at the tip of the main body. In particular, after the movable core starts moving due to the driving magnetic flux, the stopper comes into contact with the nozzle before the movable core comes into contact with the fixed core, and the maximum lift amount of the needle valve is restricted by the contact of the stopper. In this case, the nozzle that the stopper contacts is located at the tip of the main body, and even if the axial length of the main body changes unintentionally on the base side of the nozzle, it is possible to minimize the impact on the valve body lift amount. As a result, variations in injection amount can be suppressed in the gas fuel injection valve, and proper fuel injection can be performed.

[0009] The above-mentioned and other purposes, features and advantages of this disclosure will be further clarified by the following detailed description with reference to the accompanying drawings. The drawings are as follows: Figure 1 is a cross-sectional view showing the longitudinal cross-sectional structure of a fuel injector; Figure 2 is a front view of a stopper; Figure 3 shows the fuel injector assembled in a gas engine; Figure 4 shows the injection characteristics of the fuel injector; Figure 5 is a cross-sectional view showing an enlarged view of the stopper and its surrounding components; Figure 6 is a cross-sectional view showing the longitudinal cross-sectional structure of a fuel injector in a second embodiment; Figure 7 is a cross-sectional view showing a cross-section of a shim; Figure 8 is a cross-sectional view showing an enlarged view of the stopper and its surrounding components; Figure 9 shows the assembly procedure of the needle valve, spring, stopper and shim to the nozzle in a fuel injector; Figure 10 shows the fuel injector assembled in a gas engine; and Figure 11 shows the longitudinal cross-sectional structure of the tip portion of the fuel injector in a third embodiment. Figure 12 is a cross-sectional view taken along line 12-12 of Figure 11, Figure 13 is a cross-sectional view showing the longitudinal cross-sectional structure of the tip portion of the fuel injector, Figure 14 is a cross-sectional view showing the longitudinal cross-sectional structure of the tip portion of the fuel injector, Figure 15 is a cross-sectional view showing the longitudinal cross-sectional structure of the tip portion of the fuel injector, Figure 16 is a cross-sectional view taken along line 16-16 of Figure 15, Figure 17 is a cross-sectional view showing the longitudinal cross-sectional structure of the tip portion of the fuel injector in the fourth embodiment, Figure 18 is a front view of the stopper, Figure 19 is a cross-sectional view showing the longitudinal cross-sectional structure of the tip portion of the fuel injector in the fifth embodiment, Figure 20 is a cross-sectional view showing the longitudinal cross-sectional structure of the tip portion of the fuel injector, Figure 21 is a cross-sectional view showing the longitudinal cross-sectional structure of the tip portion of the fuel injector, and Figure 22 is a diagram showing a modified example of the enlarged diameter portion of the stopper.

[0010] (First Embodiment) An embodiment of the gas fuel injection valve according to the present disclosure will be described below with reference to the drawings. The gas fuel injection valve of this embodiment is applied to a direct injection gas engine (internal combustion engine) that uses gas fuels such as hydrogen, CNG (Compressed Natural Gas), and LNG (Liquefied Natural Gas), and the gas fuel is directly injected into the combustion chamber of the gas engine by the gas fuel injection valve. The gas engine is, for example, an on-board engine.

[0011] The configuration of the fuel injector 10 will be explained using Figure 1. Figure 1 shows the longitudinal cross-sectional structure of the fuel injector 10. In the following explanation, the direction in which the central axis of the fuel injector 10 extends (i.e., the vertical direction in Figure 1) is referred to as the axial direction, the direction radiating from the axis is referred to as the radial direction, and the direction circumferentially extending around the axis is referred to as the circumferential direction. In Figure 1, the upper side is the base end (upstream side) of the fuel injector 10, and the lower side is the tip end (downstream side). For the sake of explanation, using the fuel injector 10 in Figure 1 as a reference, the upper side of the fuel injector 10 will also be referred to as the upper end, and the lower side as the lower end.

[0012] The fuel injector 10 is equipped with a cylindrical housing 11. The housing 11 has an inlet 12, a body 13, and a nozzle 14. The housing 11 corresponds to the "main body". The body 13 is cylindrical in shape and extends in the axial direction, with the inlet 12 and nozzle 14 fixed to one end and the other end of the body 13 in the axial direction, respectively. A fuel passage 15 is provided inside the housing 11 for circulating gaseous fuel in the axial direction. The inlet 12 is provided with an inlet 16, and the nozzle 14 is provided with a nozzle 17. In the fuel injector 10, gaseous fuel is introduced from the inlet 16 of the inlet 12, and the fuel passage 15 is filled with gaseous fuel. When hydrogen gas is used as the gaseous fuel, gaseous fuel compressed below atmospheric pressure is supplied to the fuel passage 15 from the upstream fuel supply unit.

[0013] The housing 11 contains a needle valve 20, a stopper 40, a spring 27, an electromagnetic drive unit 30, and a bellows 50. The needle valve 20 is installed inserted into the nozzle 14's injection hole 17. The needle valve 20 has a shaft portion 21 that extends axially and is inserted into the injection hole 17, a tip valve portion 22 provided at one axial end (lower end) of the shaft portion 21, a flange-shaped enlarged diameter portion 23 provided at an intermediate axial position of the needle valve 20, and a connecting shaft portion 24 that extends from the enlarged diameter portion 23 to the electromagnetic drive unit 30. The shaft portion 21 has a sliding portion 25 that slides inside the injection hole 17. The sliding portion 25 is provided with a communication passage 25a that communicates axially. The needle valve 20 is capable of reciprocating axially with the sliding surface of the sliding portion 25 in contact with the inner circumferential surface of the injection hole 17.

[0014] The tip valve portion 22 is positioned axially outward from the nozzle 14 and faces the axial end face of the nozzle 14. In the nozzle 14, the annular axial end face surrounding the injection hole 17 is the seat portion 14a. The injection hole 17 is closed when the seat portion 14a of the nozzle 14 and the tip valve portion 22 come into contact. This state is the closed state of the fuel injection valve 10. Conversely, the injection hole 17 is opened when the seat portion 14a of the nozzle 14 and the tip valve portion 22 separate. This state is the open state of the fuel injection valve 10. The fuel injection valve 10 has an outward-opening valve structure in which the needle valve 20 moves axially outward from the housing 11 to open the injection hole 17 and also closes the injection hole 17 from the outside.

[0015] The stopper 40 is cylindrical and is installed with the needle valve 20 inserted through it. The stopper 40 has a cylindrical portion 41 that communicates in the axial direction and an enlarged diameter portion 42 provided at one end (upper end) of the cylindrical portion 41. The enlarged diameter portion 42 is provided to expand radially outward from the cylindrical portion 41. The enlarged diameter portion 42 of the stopper 40 and the enlarged diameter portion 23 of the needle valve 20 are opposite each other in the axial direction. The stopper 40 is installed with the enlarged diameter portion 42 in contact with the enlarged diameter portion 23 of the needle valve 20. The stopper 40 and the needle valve 20 may be fixed to each other in a way that makes them inseparable, or they may be separable from each other.

[0016] The nozzle 14 of the housing 11 is provided with a hollow section extending in the axial direction, which includes a nozzle 17 and a receiving recess 18 that is larger in diameter than the nozzle 17 and accommodates the tip end of the cylindrical section 41 of the stopper 40. The stopper 40 is provided with the tip end of the cylindrical section 41 housed in the receiving recess 18, and the tip surface of the cylindrical section 41 (the axial end surface on the tip side) faces the stopper-facing surface 19 of the nozzle 14. The nozzle 17 of the nozzle 14 and the hollow section 41a of the cylindrical section 41 of the stopper 40 are in axial communication, and the shaft 21 of the needle valve 20 is inserted through the nozzle 17 and the hollow section 41a.

[0017] The enlarged diameter portion 42 of the stopper 40 serves as a spring holder, holding the spring 27 in a state that biases the needle valve 20 in the closing direction. A spring 27, made of a compression coil spring, is provided between the enlarged diameter portion 42 of the stopper 40 and the inner end face of the nozzle 14, and the spring 27 biases the needle valve 20 and the stopper 40 in a direction that closes the injection hole 17. In this state, the needle valve 20 and the stopper 40 can reciprocate together in the axial direction. The spring 27 corresponds to the "biasing member". In the closed state of the fuel injection valve 10 (as shown in the figure), the tip surface of the stopper 40 (more specifically, the tip surface of the cylindrical portion 41) and the stopper-facing surface 19 of the nozzle 14 are separated from each other, and a predetermined gap G1 is formed between these two surfaces.

[0018] The cylindrical portion 41 of the stopper 40 is provided with a plurality of communication holes 43 in the circumferential direction. Specifically, as shown in Figure 2, the cylindrical portion 41 is provided with, for example, four communication holes 43 arranged evenly in the circumferential direction. The gas fuel introduced into the housing 11 flows into the injection hole 17 through the communication holes 43 of the stopper 40. The number and shape of the communication holes 43 are arbitrary. In addition to holes extending in a direction perpendicular to the axial direction, the communication holes 43 may also extend in a direction oblique to the direction perpendicular to the axial direction.

[0019] The electromagnetic drive unit 30 includes a fixed core 31 fixed within the housing 11, a movable core 32 that opens the needle valve 20, and a solenoid 33 that generates a driving magnetic flux to attract the movable core 32 to the fixed core 31. Both the fixed core 31 and the movable core 32 are made of magnetic material. The fixed core 31 is fixed within the housing 11 at a position opposite the axial direction from the injection hole 17. The fixed core 31 is provided with a guide passage 34 that guides the gas fuel introduced from the inlet 16 to the downstream side.

[0020] Although not shown in the diagram, the fixed core 31 may be fixed, for example, within the housing 11 by an annular fixing member. The method of fixing the fixed core 31 is arbitrary, and it is also possible to fix the fixed core 31 to the housing 11 by adhesive or the like without using a fixing member.

[0021] The fixed core 31 is provided with a recess 35 that opens to the lower end side of the fuel injection valve 10, i.e., to the needle valve 20 side. A movable core 32 is positioned within the recess 35 so as to be movable in the axial direction. The solenoid 33 is provided integrated with the fixed core 31. The recess 35 of the fixed core 31 has a large-diameter recess 35a and a small-diameter recess 35b on the outlet side of the large-diameter recess 35a. The movable core 32 has a large-diameter portion 32a and a small-diameter portion 32b that extends from the large-diameter portion 32a toward the lower axial end. The movable core 32 is movable in the axial direction with the large-diameter portion 32a of the movable core 32 housed in the large-diameter recess 35a of the fixed core 31 and the small-diameter portion 32b of the movable core 32 housed in the small-diameter recess 35b of the fixed core 31.

[0022] In the closed state of the fuel injection valve 10 (as shown in the figure), a predetermined gap G2 is formed between the fixed core 31 and the movable core 32. When the solenoid 33 is energized, a driving magnetic flux is generated, and this driving magnetic flux attracts the large-diameter portion 32a of the movable core 32 toward the stepped portion 31a of the fixed core 31, causing the movable core 32 to move toward the axial lower end. The axial end surface of the needle valve 20 can come into contact with the tip surface of the axial tip of the movable core 32 (more specifically, the tip of the small-diameter portion 32b). Therefore, when the movable core 32 moves toward the axial lower end, the needle valve 20 moves toward the open side together with the movable core 32.

[0023] Within the housing 11, a cylindrical bellows 50 that can expand and contract in the axial direction is provided between the enlarged diameter portion 23 of the needle valve 20 and the electromagnetic drive unit 30, surrounding the connecting shaft portion 24 of the needle valve 20. In other words, the portion of the needle valve 20 from the axial intermediate position to the axial end on the movable core 32 side is surrounded by the bellows 50. The lower end of the bellows 50 is fixed to the enlarged diameter portion 23 of the needle valve 20, and the upper end is fixed to an annular member 37 that is fixed to the fixed core 31 and surrounds the cylindrical guide 36. The lower end of the bellows 50 that is fixed to the needle valve 20 is the movable end, and the bellows 50 can expand and contract in the axial direction as the needle valve 20 moves.

[0024] The housing 11 is divided by a bellows 50 into an annular fuel passage 15 through which gaseous fuel passes, and a central space 51 located inside the fuel passage 15 and housing the connecting shaft portion 24 of the needle valve 20. In other words, the bellows 50 is provided as an isolation member that separates the fuel passage 15 from the central space 51 surrounding the needle valve 20 within the housing 11.

[0025] The recess 35 of the fixed core 31 is open to the atmosphere through the inlet 12 and the atmospheric vent 38 provided in the fixed core 31. In this case, the recess 35 of the fixed core 31 (i.e., the housing space for the movable core 32) and the central space 51 are in communication, and both are under atmospheric pressure. In other words, the central space 51 is under atmospheric pressure. It is also possible to configure the recess 35 of the fixed core 31 and the central space 51 to be filled with a liquid such as lubricating oil in an uncompressible state.

[0026] In the fuel injection valve 10 with the above configuration, when the valve is opened for fuel injection, the solenoid 33 is energized, generating a driving magnetic flux that attracts the movable core 32 to the fixed core 31. As the movable core 32 moves, the needle valve 20 lifts to the open position against the biasing force of the spring 27, and gaseous fuel is injected from the injection hole 17. When the fuel injection valve 10 is closed, the solenoid 33 is de-energized, and the driving magnetic flux disappears, releasing the attraction of the movable core 32 to the fixed core 31. The biasing force of the spring 27 then returns the needle valve 20 to the closed position (i.e., the position where it contacts the seat portion 14a of the nozzle 14). This closes the injection hole 17, and fuel injection ends.

[0027] The fuel injector 10 has a balance valve structure using a bellows 50. In other words, in the fuel injector 10, the bellows 50 is installed between the enlarged diameter portion 23 of the needle valve 20 and the electromagnetic drive unit 30, so that fuel pressure acts in opposite directions on the tip valve portion 22 and the enlarged diameter portion 23 of the needle valve 20 within the housing 11. This maintains a pressure balance with respect to the needle valve 20. Therefore, the biasing force of the spring 27 and the solenoid electromagnetic force can be set independently of the fuel pressure.

[0028] Figure 3 shows the fuel injector 10 assembled to a gas engine. In Figure 3, the cylinder head 61 of the gas engine is provided with an assembly hole 62 for assembling the fuel injector 10. The assembly hole 62 has a body housing portion 63 that accommodates the body 13 of the fuel injector 10, and a communication hole portion 64 that extends from the body housing portion 63 and leads to the combustion chamber CA of the gas engine. The communication hole portion 64 is a through hole with a smaller opening area than the body housing portion 63, and the bottom of the body housing portion 63 is a contact surface 65 that abuts against the axial end face 11a of the housing 11 when the fuel injector 10 is assembled. The cylinder head 61 corresponds to the engine body. It is also possible to assemble the fuel injector 10 to the cylinder block, which is the engine body.

[0029] The fuel injector 10 is housed in the mounting hole 62 of the cylinder head 61 and is fastened and secured at the base end side of the housing 11 (i.e., the entrance side of the mounting hole) by fasteners 66 such as nuts. In this case, the fuel injector 10 is assembled to the cylinder head 61 with the axial end face of the housing 11 in contact with the contact surface 65 on the cylinder head 61 side and with an axial force applied in the axial direction of the fuel injector 10.

[0030] In short, in the fuel injector 10, the outer circumference of the tip portion of the housing 11 is reduced in diameter, and this reduced portion becomes the nozzle 14. The fuel injector 10 is assembled to the cylinder head 61 with the stepped axial end surface 11a formed by the reduction in diameter of the housing 11 in contact with the contact surface 65 on the cylinder head 61 side, and with a predetermined tightening force applied axially from the base end side opposite to the tip portion of the housing 11.

[0031] Incidentally, when the fuel injector 10 is assembled to the cylinder head 61 of a gas engine as shown in Figure 3, axial forces act on both sides of the body 13 in the housing 11 of the fuel injector 10, and it is conceivable that the axial length (shaft length) of the body 13 may change due to these axial forces. Furthermore, if the tightening force by the fasteners 66 varies, or if the cylinder head 61 expands or contracts due to changes in engine temperature, it is also conceivable that the shaft length of the body 13 may change.

[0032] Furthermore, when the axial length of the body 13 changes, the relative position of the fixed core 31 with respect to the movable core 32 changes, which in turn changes the gap dimension between the fixed core 31 and the movable core 32. This can cause the maximum lift amount of the needle valve 20 to change unintentionally, potentially altering the injection rate, which is the amount of fuel injected per unit time. Consequently, there are concerns that this could lead to variations in the fuel injection amount.

[0033] Figure 4 shows the injection characteristics of the fuel injector 10. In Figure 4, (a) shows the injection characteristics of the fuel injector 10 as it is shipped from the manufacturing plant, and (b) shows the injection characteristics of the fuel injector 10 when it is assembled in a gas engine and in actual use. In Figures 4(a) and (b), the horizontal axis is time, and the vertical axis is the injection rate or valve lift amount.

[0034] The injection characteristics shown in Figure 4(a) represent the performance of the fuel injector 10 alone before assembly into the gas engine. The injection rate or valve lift amount when the needle valve 20 is at its maximum opening is a predetermined value A.

[0035] In contrast, in actual use, as described above, when the gap dimension between the fixed core 31 and the movable core 32 changes due to a change in the axial length of the body 13, the maximum lift amount and injection rate of the needle valve 20 change relative to a predetermined value A, as shown in Figure 4(b), and consequently, variations in the fuel injection amount occur. For example, when the axial length of the body 13 increases, the gap dimension between the fixed core 31 and the movable core 32 decreases, and the maximum lift amount and injection rate of the needle valve 20 decrease. As a result, the fuel injection amount unintentionally changes to a decrease. Also, when the axial length of the body 13 decreases, the gap dimension between the fixed core 31 and the movable core 32 increases, and the maximum lift amount and injection rate of the needle valve 20 increase. As a result, the fuel injection amount unintentionally changes to an increase.

[0036] Furthermore, even if an axial force is not necessarily acting on the body 13 of the fuel injector 10 as shown in Figure 3, it is conceivable that changes in the maximum lift amount and injection rate of the needle valve 20 may occur due to the expansion and contraction of the body 13 in response to temperature changes.

[0037] Therefore, in this embodiment, even if the axial length of the body 13 changes, in order to reduce the variation in fuel injection amount caused by that change in axial length, the fuel injection valve 10 is configured such that the stopper 40 contacts the nozzle 14 after the movable core 32 starts moving due to the driving magnetic flux but before the movable core 32 contacts the fixed core 31, thereby restricting the maximum lift amount of the needle valve 20. In this case, the nozzle 14 that the stopper 40 contacts is located at the tip of the housing 11, so even if the axial length of the body 13 on the base end side of the housing 11 changes unintentionally, it is possible to reduce the impact on the valve body lift amount. As a result, variations in injection amount are suppressed.

[0038] Specifically, as shown in Figure 1, when the axial gap dimension between the axial end face of the stopper 40 and the stopper-facing surface 19 on the nozzle 14 that faces the axial end face of the stopper 40 is D1, and the axial gap dimension between the fixed core 31 and the movable core 32 is D2, the configuration is such that the gap dimensions D1 and D2 satisfy the relationship D1 < D2. Note that the gap dimension D2 between the fixed core 31 and the movable core 32 is the gap dimension when the movable core 32 and the needle valve 20 are in axial contact with each other.

[0039] In the fuel injection valve 10, the material of the stopper 40 should have a coefficient of linear expansion equivalent to that of the needle valve 20. Furthermore, the material of the stopper 40 should have a coefficient of linear expansion equivalent to that of the nozzle 14. For example, the material of the stopper 40 is SUS440C, a martensitic stainless steel. The materials of the needle valve 20 and nozzle 14 should be the same material as the stopper 40 or materials with a similar coefficient of linear expansion. This suppresses changes in valve body lift due to temperature changes. Note that in the fuel injection valve 10, the nozzle 14, needle valve 20, and stopper 40 are all parts that slide against each other, whereas the body 13 is not a sliding part. Therefore, in the housing 11, the materials of the body 13 and the nozzle 14 should be different. The body 13 should be, for example, SUS304, an austenitic stainless steel, or steel (carbon steel).

[0040] Figure 5 is a longitudinal cross-sectional view showing an enlarged view of the stopper 40 and its surrounding structure. In Figure 5, when the opening dimension of the injection hole 17 is D11 and the inner diameter dimension of the cylindrical portion 41 of the stopper 40 is D12, the relationship between D11 and D12 is D11 < D12. In this case, even if the cylindrical portion 41 of the stopper 40 is incorporated into the hollow part of the nozzle 14, the narrowing of the fuel flow path by the stopper 40 is suppressed. Note that these dimensions D11 and D12 may also be D11 = D12.

[0041] Further, on the inner peripheral side of the cylindrical portion 41 of the stopper 40, an annular passage 45 for allowing gas fuel to pass is formed between the cylindrical portion 41 and the shaft portion 21 of the needle valve 20. Gas fuel flows into the annular passage 45 from the upstream side through a plurality of communication holes 43 provided in the cylindrical portion 41. Here, when the passage cross-sectional area of the annular passage 45 is S1 and the total opening area of the respective communication holes 43 in the stopper 40 is S2, they have a relationship of S1 ≤ S2.

[0042] In the fuel injection valve 10, inside the housing 11, gas fuel passes through the communication holes 43 provided in the cylindrical portion 41 of the stopper 40, and further passes through the annular passage 45 formed between the shaft portion 21 of the needle valve 20 on the inner peripheral side of the cylindrical portion 41 and is guided to the injection holes 17.

[0043] In FIG. 1, in the fuel injection valve 10, the end position on the upper end side of the housing 11 as viewed in the axial direction, that is, the position of the base end portion (base end position) where an axial force acts on the body 13 in the engine assembled state is defined as X1. Further, - the position of the opposing surface (step portion 31a) of the fixed core 31 with respect to the movable core 32 in the electromagnetic drive portion 30 is X2, - the fixed position of the bellows 50 in the needle valve 20 is X3, - the position of the axial end face 11a that abuts against the abutting surface 65 of the cylinder head 61 in the housing 11 is X4, - the stopper abutting position (the position of the stopper opposing surface 19) where the stopper 40 abuts in the nozzle 14 is X5, - the tip position of the nozzle 14 is defined as X6.

[0044] Regarding the axial positional relationship of these respective positions X1 to X6, in the order of X2, X3, X4, X5, X6, they are positions that are separated from the base end position X1 of the housing 11 toward the axial tip side. In other words, the respective positions X1 to X6 are positions that are separated from the tip position X6 of the nozzle 14 toward the axial base end side in the order of X5, X4, X3, X2, X1. In this case, the stopper abutting position X5 of the nozzle 14 is on the tip side of the injection valve with respect to the fixed position X3 of the bellows 50 with respect to the needle valve 20 in the axial direction. Further, the stopper abutting position X5 is on the tip side of the injection valve with respect to the position X4 of the axial end face 11a of the housing 11 in the axial direction.

[0045] According to the embodiment described in detail above, the following excellent effects can be obtained.

[0046] In the fuel injection valve 10, a stopper 40 is provided which axially inserts the needle valve 20 and is integrally reciprocable axially with the needle valve 20. When the needle valve 20 opens due to the generation of driving magnetic flux, the stopper 40 is made to contact the nozzle 14 of the housing 11. In particular, after the start of movement of the movable core 32 by the driving magnetic flux and before the movable core 32 contacts the fixed core 31, the stopper 40 contacts the nozzle 14, and the maximum lift amount of the needle valve 20 is regulated by the contact of the stopper 40. In this case, the nozzle 14 against which the stopper 40 contacts is located at the tip portion of the housing 11, and even if the axial length of the body 13 of the housing 11 changes unintentionally, it is possible to make it difficult to affect the valve body lift amount. As a result, in the fuel injection valve 10, it is possible to suppress the variation in injection amount and perform appropriate fuel injection.

[0047] The opening dimension D11 of the injection hole 17 and the inner diameter dimension D12 of the cylindrical portion 41 of the stopper 40 are set in the relationship of D11 ≤ D12. In this case, even in a configuration where the cylindrical portion 41 of the stopper 40 is incorporated into the hollow portion of the nozzle 14, it is possible to suppress the fuel flow path from being restricted by the stopper 40. Therefore, it is possible to achieve a large flow rate in the fuel injection valve 10.

[0048] In the fuel injection valve 10, inside the housing 11, the gaseous fuel passes through the communication hole 43 provided in the cylindrical portion 41 of the stopper 40, and further passes through the annular passage 45 formed between the shaft portion 21 of the needle valve 20 on the inner peripheral side of the cylindrical portion 41 and is guided to the injection hole 17. Thereby, even if the cylindrical stopper 40 is provided so as to surround the shaft portion of the needle valve 20, it is possible to appropriately circulate the gaseous fuel in the path to the injection hole 17. By providing the communication hole 43 in the cylindrical portion 41 extending in the axial direction of the stopper 40, it is easy to provide a communication hole 43 of a desired size.

[0049] The cross-sectional area S1 of the annular passage 45 between the cylindrical portion 41 of the stopper 40 and the shaft portion 21 of the needle valve 20, and the total opening area S2 of each communication hole 43 in the stopper 40, are set to the relationship S1 ≤ S2. This makes it possible to suppress the inconvenience of the gas fuel flow rate being unnecessarily reduced in a configuration in which the needle valve 20 is surrounded by a cylindrical stopper 40.

[0050] The material of the stopper 40 is made of a material having the same coefficient of linear expansion as the needle valve 20 and nozzle 14. This makes it possible to suppress changes in the valve body lift amount even if the axial length of the nozzle 14 changes due to temperature changes.

[0051] By using a bellows 50 to create a balance valve structure for the fuel injector 10, the required suction force of the needle valve 20 can be reduced, enabling a higher flow rate for the fuel injector 10. Furthermore, the stopper 40 is configured to contact the stopper-facing surface 19 of the nozzle 14 at a position (X5 in Figure 1) on the axial end side of the fixed portion of the bellows 50 in the needle valve 20. This makes it possible to achieve a configuration that is less affected by changes in the axial length of the housing 11, even when the housing 11 is assembled in the cylinder head 61 with axial force applied to it.

[0052] In the housing 11 of the fuel injector 10, the stopper 40 is positioned (X5 in Figure 1) on the axial tip side of the axial end face 11a that abuts against the cylinder head 61, and contacts the stopper-facing surface 19 of the nozzle 14. This configuration makes it possible to achieve a configuration that is less affected by changes in the axial length of the housing 11, even when the housing 11 is assembled in the cylinder head 61 with an axial force applied to it.

[0053] (Second Embodiment) Next, as a second embodiment, a fuel injector 10A will be described, which has a modified configuration of the fuel injector 10 described in the first embodiment. Figure 6 is a cross-sectional view showing the configuration of the fuel injector 10A.

[0054] The fuel injector 10A differs in its configuration from the fuel injector 10 of the first embodiment in that, in the axial direction, an annular plate-shaped shim 71 is incorporated between the enlarged diameter portion 23 of the needle valve 20 and the enlarged diameter portion 42 of the stopper 40, surrounding the shaft portion 21 of the needle valve 20.

[0055] Figure 7 is a cross-sectional view showing the cross-section of the shim 71, and is also the cross-sectional view taken along line 7-7 in Figure 6. Figure 8 is a longitudinal cross-sectional view showing an enlarged view of the stopper 40 and its surrounding structure. Note that in Figure 7, the outer circumference of the enlarged diameter portion 23 of the needle valve 20 and the inner circumference of the cylindrical portion 41 of the stopper 40 are projected onto each other by dashed lines.

[0056] As shown in Figure 7, the shim 71 is made of a plate material that is roughly C-shaped in plan view. A part of the shim 71 in the circumferential direction is open, and the distance D21 of the opening 72 is larger than the diameter of the shaft portion 21 of the needle valve 20. Therefore, the shim 71 can be assembled to the shaft portion 21.

[0057] Furthermore, as shown in Figure 8, the shim 71 is provided sandwiched in the axial direction between the enlarged diameter portion 23 of the needle valve 20 and the upper end portion (enlarged diameter portion 42) of the stopper 40. Specifically, the shim 71 is positioned such that one axial end face (upper surface in the figure) abuts against the enlarged diameter portion 23 of the needle valve 20, and the other axial end face (lower surface in the figure) abuts against the enlarged diameter portion 42 of the stopper 40. In this configuration, the force applied to the needle valve 20 and the stopper 40 is transmitted to each other via the shim 71, allowing the needle valve 20, the stopper 40, and the shim 71 to be displaced integrally in the axial direction.

[0058] Here, if we let the inner diameter of the shim 71 be D31 and its outer diameter be D32, the outer diameter of the enlarged portion 23 of the needle valve 20 be D33, and the inner diameter of the cylindrical portion 41 of the stopper 40 be D34, then the inner diameter of the shim 71 D31 and the outer diameter of the enlarged portion 23 of the needle valve 20 D33 satisfy D31 < D33. In other words, the inner diameter of the shim is smaller than the outer diameter of the needle (outer diameter of the enlarged portion 23). Also, the outer diameter of the shim 71 D32 and the inner diameter of the cylindrical portion 41 of the stopper 40 D34 satisfy D32 > D34. In other words, the outer diameter of the shim is larger than the inner diameter of the stopper. Note that D31 to D34 are radii or diameters, and are dimensions that are unified as either radius or diameter.

[0059] Furthermore, the outer diameter dimension D33 of the enlarged portion 23 of the needle valve 20 and the inner diameter dimension D34 of the cylindrical portion 41 of the stopper 40 are such that D33 < D34. In this case, the assembly of the cylindrical stopper 40 to the needle valve 20 is easy. The details will be described later.

[0060] These dimensions D33 and D34 may be D33 = D34. If the outer diameter dimension D33 of the enlarged diameter portion 23 of the needle valve 20 and the inner diameter dimension D34 of the cylindrical portion 41 of the stopper 40 are the same, for example, without using a shim 71, the outer circumferential surface of the enlarged diameter portion 23 of the needle valve 20 and the inner circumferential surface of the stopper 40 may be placed facing each other, and the stopper 40 may be fixed to the enlarged diameter portion 23 of the needle valve 20 by welding or adhesive means.

[0061] Furthermore, if the outer diameter dimension (D33) of the enlarged portion 23 of the needle valve 20 is replaced with α1 and the inner diameter dimension (D34) of the stopper 40 is replaced with α2, then it is desirable that the respective dimensions α1 and α2 satisfy α1 ≤ α2. Also, if the inner diameter dimension (D31) of the shim is replaced with β1, the outer diameter dimension (D33) of the enlarged portion 23 is replaced with β2, the outer diameter dimension (D32) of the shim is replaced with β3, and the inner diameter dimension (D34) of the stopper 40 is replaced with β4, then it is desirable that β1 < β2, β3 > β4, and β2 < β4.

[0062] The enlarged diameter portion 42 of the stopper 40 is provided with an assembly recess 44 for assembling a shim 71. The assembly recess 44 is provided on the axial end face of the stopper 40. The assembly recess 44 is designed to prevent misalignment or detachment of the shim 71 in a configuration in which the shim 71 is assembled between the needle valve 20 and the stopper 40. The axial depth dimension D35 of the assembly recess 44 is smaller than the thickness dimension D36 of the shim 71, and is also smaller than the gap dimension (D1 in Figure 6) between the axial end faces of the stopper 40 and the nozzle 14 that face each other in the axial direction.

[0063] Figure 9 shows the assembly procedure for the needle valve 20, spring 27, stopper 40, and shim 71 relative to the nozzle 14 in the fuel injection valve 10A.

[0064] First, in Figure 9(a), the needle valve 20 and spring 27 are assembled to the nozzle 14. At this time, the outer diameter of the tip valve portion 22 of the needle valve 20 is larger than the opening size of the nozzle 17, but by making the outer diameter of the enlarged portion 23 smaller than the opening size of the nozzle 17, it is possible to insert the needle valve 20 into the nozzle 14 from the tip side (left side in the figure). In other words, the relationship between the opening size D11 of the nozzle 17 shown in Figure 5 and the outer diameter D33 of the enlarged portion 23 shown in Figure 8 is D11 > D33. However, D11 = D33 is also acceptable. The spring 27 is assembled from the side opposite to the needle valve 20 (right side in the figure).

[0065] Next, in Figure 9(b), the stopper 40 is assembled. At this time, as explained in Figure 8, the outer diameter dimension D33 of the enlarged portion 23 of the needle valve 20 and the inner diameter dimension D34 of the cylindrical portion 41 of the stopper 40 are D33 < D34, so it is possible to assemble the stopper 40 closer to the tip than the enlarged portion 23 of the needle valve 20.

[0066] Next, in Figure 9(c), the shim 71 is assembled. At this time, the open portion 72 of the shim 71 is passed through the shaft portion 21 of the needle valve 20 to assemble the shim 71. As a result, the shim 71 is positioned in the axial direction between the enlarged diameter portion 23 of the needle valve 20 and the enlarged diameter portion 42 of the stopper 40. When assembling the shim 71, it is preferable to press the stopper 40 against the biasing force of the spring 27 toward the nozzle 14 side (left side in the figure) so that the gap between the enlarged diameter portion 23 of the needle valve 20 and the enlarged diameter portion 42 of the stopper 40 is widened before assembling the shim 71. Here, as explained in Figure 8, the depth dimension D35 of the assembly recess 44 in the stopper 40 is smaller than the gap dimension (D1 in Figure 6) between the stopper 40 and the nozzle 14. In other words, the gap dimension D1 between the stopper 40 and the nozzle 14 is larger than the depth dimension D35 of the assembly recess 44. Therefore, when the stopper 40 is pressed against the nozzle 14 side against the biasing force of the spring 27, the shim 71 can be properly assembled between the enlarged diameter portions 23 and 42 and within the assembly recess 44 of the stopper 40, while being aligned with the end face of the enlarged diameter portion 23 of the needle valve 20.

[0067] Subsequently, as shown in Figure 9(d), when the force pressing the stopper 40 toward the nozzle 14 (left side of the figure) is released, the stopper 40 moves due to the biasing force of the spring 27, and the shim 71 is sandwiched between the enlarged diameter portion 23 of the needle valve 20 and the enlarged diameter portion 42 of the stopper 40.

[0068] Incidentally, in the fuel injection valve 10 described in the first embodiment, the needle valve 20 and stopper 40 cannot be assembled as shown in Figure 9. Therefore, in the fuel injection valve 10 of the first embodiment, it is preferable that the needle valve 20 and stopper 40 be assembled to the nozzle 14 by one of the following: making the enlarged diameter portion 23 of the needle valve 20 a separate component that can be retrofitted to the shaft portion 21; making the shaft portion 21 divisible in the axial direction; or making the nozzle 14 divisible in the circumferential direction.

[0069] In addition to the effects of the fuel injector 10 in the first embodiment, the fuel injector 10A with the above configuration provides the following effects.

[0070] The outer diameter dimension D33 of the enlarged portion 23 in the needle valve 20 and the inner diameter dimension D34 of the stopper 40 are set to the relationship D33 ≤ D34. This allows the cylindrical stopper 40 to be suitably assembled to the needle valve 20 without interfering with the enlarged portion 23 of the needle valve 20.

[0071] In the fuel injection valve 10, a shim 71 is provided between the enlarged diameter portion 23 of the needle valve 20 and the axial end face of the stopper 40, surrounding the shaft portion 21 of the needle valve 20. In this configuration, the inner diameter of the shim is smaller than the outer diameter of the needle (outer diameter of the enlarged diameter portion 23), and the outer diameter of the shim is larger than the inner diameter of the stopper. This causes the axial end faces of the needle valve 20 and the shim 71 to be in contact with each other, and the axial end faces of the stopper 40 and the shim 71 to be in contact with each other. As a result, the load can be properly transmitted in the axial direction between the needle valve 20 and the stopper 40 via the shim 71.

[0072] In a configuration using a shim 71 with the above-described dimensions relative to the needle valve 20 and stopper 40, it is possible to insert and assemble the stopper 40 to the tip side of the enlarged diameter portion 23 relative to the needle valve 20, while achieving integrated operation of the needle valve 20 and stopper 40 without fixing them to each other by welding or adhesive. Therefore, the work required to assemble the needle valve 20 and stopper 40 can be simplified.

[0073] Furthermore, since the relationship between the outer diameter dimension D33 of the enlarged portion 23 of the needle valve 20 and the inner diameter dimension D34 of the stopper 40 is D33 < D34, the cylindrical stopper 40 can be suitably assembled to the needle valve 20 without interfering with the enlarged portion 23 of the needle valve 20.

[0074] An assembly recess 44 is provided on the axial end face of the stopper 40, and the shim 71 is assembled into the assembly recess 44. This prevents the shim 71, which is provided so as to surround the shaft portion 21 of the needle valve 20, from shifting position or falling off. Furthermore, the axial depth dimension of the assembly recess 44 is made smaller than the gap dimension between the axial end faces of the stopper 40 and the nozzle 14. In other words, the gap dimension between the stopper 40 and the nozzle 14 is larger than the depth dimension of the assembly recess 44, which allows for efficient assembly of the shim 71 between the enlarged diameter portion 23 of the needle valve 20 and the enlarged diameter portion 42 of the stopper 40.

[0075] (Third Embodiment) Next, the fuel injection valve 10 of the third embodiment will be described. In this embodiment, a stopper 40 generates a differential pressure between the upstream and downstream sides of the fuel passage 15 within the housing 11 of the fuel injection valve 10, and this differential pressure assists in opening the needle valve 20.

[0076] The fuel injector 10 of this embodiment is designed based on the following circumstances. In a direct-injection type fuel injector 10, when mounted on the cylinder head of the engine, a back pressure acting as a valve-closing load acts on the tip valve portion 22 of the needle valve 20 from the axially outer side, which is the combustion chamber side. In this case, when opening the fuel injector 10, it becomes necessary to open the needle valve 20 against the valve-closing load from the axially outer side. In other words, in an outward-opening type fuel injector 10, it is necessary to open the needle valve 20 while taking into account that the pressure inside the combustion chamber (cylinder pressure) acts in the direction of closing the valve.

[0077] Furthermore, as shown in Figure 10, for example, in a fuel injector 10 mounted in a mounting hole 102 of the cylinder head 101 of an engine, a cylindrical cap 103 is positioned at the tip of the fuel injector 10, and fuel is injected from the fuel injector 10 into the cap 103. The cap 103 forms a sub-chamber 104 within the engine cylinder. The cap 103 is provided with a communication hole 106 that leads to the main combustion chamber 105 of the engine. The communication hole 106 is provided, for example, at an angle to the centerline (axis) of the cylinder. This makes it possible to generate gaseous fuel vortices such as tumble flow and swirl flow in the main combustion chamber 105.

[0078] When fuel is injected into the small-volume cap 103, the back pressure of the needle valve 20 may increase, potentially increasing the valve closing load (FA in the figure). In such cases, countermeasures are necessary to ensure proper fuel injection.

[0079] In addition to providing a cap 103 as described above, another possible configuration for forming a sub-chamber 104 on the tip side of the fuel injector 10 is to place a cylindrical sleeve over the nozzle 14 of the fuel injector 10, and form the sub-chamber 104 on the tip side of the sleeve, surrounding the tip valve portion 22 of the needle valve 20. It is preferable that a communication hole for generating vortices is provided at the tip of the sleeve.

[0080] In this embodiment, the needle valve 20 is designed to open properly even when subjected to high back pressure from the engine combustion chamber side, as described above.

[0081] The details of the fuel injector 10 in this embodiment will be described below. Here, the basic configuration of the fuel injector 10 is the same as that of the fuel injector 10A described in the second embodiment, and a part of its configuration has been modified. However, it is also possible to apply the fuel injector 10 of the first embodiment.

[0082] Figure 11 is a cross-sectional view showing the configuration of the fuel injection valve 10 near the axial tip. In Figure 11, components that are the same as those described in Figures 1 and 6 are given the same component numbers. Figure 12 is a cross-sectional view taken along line 12-12 of Figure 11.

[0083] In the fuel injection valve 10 shown in Figure 11, the configuration of the stopper 40 has been partially modified. Specifically, in the stopper 40, the enlarged diameter portion 42 provided on one axial end of the cylindrical portion 41 is expanded radially outward compared to the configurations in Figures 1 and 6. An annular gap is formed between the circular outer edge of the enlarged diameter portion 42 and the housing 11, and this gap serves as a connecting passage 111. In this case, the fuel passage 15 is divided into an upstream passage 112 and a downstream passage 113 by the stopper 40. That is, in the fuel passage 15, the upstream side of the enlarged diameter portion 42 is the upstream passage 112, and the downstream side of the enlarged diameter portion 42 is the downstream passage 113.

[0084] In the stopper 40, the stopper pressure-receiving surface 114, which is the upper surface in the diagram, faces the upstream passage 112 in the enlarged diameter portion 42. In the needle valve 20, the tip pressure-receiving surface 115, which is the upper surface in the diagram, faces the downstream passage 113 in the tip valve portion 22.

[0085] The outer edge of the enlarged diameter portion 42 is circular (perfect circle) and concentric with the inner circumferential surface of the housing 11, and a communication passage 111 of the same width is formed between the housing 11 and the enlarged diameter portion 42 around the entire circumference. In this configuration, the communication passage 111 is provided with a uniform width in the circumferential direction centered on the axis of the needle valve 20.

[0086] In the fuel injection valve 10 having the configuration shown in Figure 11, when gas fuel is injected from the nozzle 17 by the lift of the needle valve 20 due to the energization of the solenoid, the gas fuel flows through the communication passage 111 outside the enlarged diameter portion 42 of the stopper 40. That is, as the needle valve 20 opens, the gas fuel flows from the upstream passage 112 to the downstream passage 113. At this time, the pressure loss that occurs when the gas fuel passes through the communication passage 111 creates a pressure difference, making the downstream passage 113 lower in pressure than the upstream passage 112. This pressure difference provides an opening assist, which helps lift the needle valve 20 to the opening side. In other words, the throttling effect that occurs when the gas fuel passes through the communication passage 111 creates a pressure difference between the upstream passage 112 and the downstream passage 113, and this pressure difference assists in opening the needle valve 20.

[0087] When the stopper 40 operates in conjunction with the opening operation of the needle valve 20, it is desirable that the opening area of ​​the communication passage 111 remains constant regardless of the lift amount of the needle valve 20. In this embodiment, the cylindrical portion (body 13) on the radially outer side of the enlarged diameter portion 42 in the housing 11 is cylindrical in shape with the same diameter in the axial direction, and the enlarged diameter portion 42 reciprocates in the axial direction along the inner circumferential surface of the cylindrical portion. In this case, the opening area of ​​the communication passage 111 is kept constant regardless of the lift of the needle valve 20. Therefore, there is no fluctuation in the opening force when the needle valve 20 operates to the full lift position.

[0088] Furthermore, the connecting passage 111 should ideally create a 3-30% differential pressure relative to the gas fuel supply pressure to the fuel passage 15 in the upstream passage 112 and the downstream passage 113. This differential pressure should ideally assist in opening the needle valve 20 and prevent a decrease in the gas fuel injection amount. The gas fuel supply pressure to the fuel passage 15, i.e., the fuel pressure in the upstream passage 112, is, for example, 5 MPa. In this embodiment, the connecting passage 111 is designed to create a 3-30% pressure drop relative to this supply pressure when gas passes through it. More preferably, the connecting passage 111 should create a 5-20% differential pressure relative to the gas fuel supply pressure.

[0089] When S11 is the pressure-receiving area in the enlarged diameter portion 42 of the stopper 40 that receives pressure axially from the upstream passage 112, and S12 is the pressure-receiving area in the tip valve portion 22 of the needle valve 20 that receives pressure axially from the downstream passage 113, the relationship between S11 and S12 is S11 > S12.

[0090] When comparing the pressure-receiving area S11 on the stopper 40 side with the pressure-receiving area S12 on the needle valve 20 side, the pressure-receiving area S11 is preferably calculated as "S11 = π × D41^2 / 4" based on the outer diameter dimension D41 of the enlarged diameter portion 42. Similarly, the pressure-receiving area S12 is preferably calculated as "S12 = π × D42^2 / 4" based on the seat diameter dimension D42 of the tip valve portion 22.

[0091] The tip of the fuel injection valve 10 may be configured as shown in detail in Figure 13, and the seat diameter dimension D42 of the tip valve portion 22 may be the diameter dimension of the portion that contacts the seat portion 14a of the tapered nozzle 14. Instead of the configuration shown in Figure 13, the tip valve portion 22 may be tapered, as opposed to the seat portion 14a.

[0092] According to the relationship S11 > S12, the enlarged diameter portion 42, which receives high pressure, is larger than the tip valve portion 22, which receives low pressure. Therefore, this configuration is suitable for increasing the opening force of the needle valve 20 in the axial direction.

[0093] In the fuel injection valve 10 shown in Figure 11, the opening area in the flow direction in which gas fuel flows from the upstream side to the downstream side is preferably such that the opening area of ​​the communication passage 111 is the smallest among the gas fuel path downstream of the fixed core 31 (see Figure 6) and up to the outlet 17a of the injection hole 17, excluding the opening area of ​​the outlet 17a. The opening area of ​​the outlet 17a is the opening area of ​​the tip of the injection valve when the needle valve 20 is in the full-lift state.

[0094] Furthermore, the opening area of ​​the communication passage 111 is preferably larger than the opening area of ​​the needle valve 20 in the fully lifted state at the outlet 17a of the injection hole 17. This suppresses a decrease in the injection amount while narrowing the opening area of ​​the gas fuel path to generate differential pressure in the communication passage 111 upstream of the outlet 17a of the injection hole 17.

[0095] Specifically, the opening area of ​​the communication passage 111 (the opening area of ​​the throttling section) should be approximately 120 to 300% of the opening area of ​​the nozzle outlet when the needle valve 20 is in the full-lift state. More preferably, the opening area of ​​the communication passage 111 should be approximately 150 to 250% of the opening area of ​​the nozzle outlet when the needle valve 20 is in the full-lift state.

[0096] In a configuration where the opening of the needle valve 20 is assisted in the fuel injection valve 10, it is desirable to define conditions under which the needle valve 20 can be reliably closed after the solenoid is de-energized. The closing conditions for the needle valve 20 are explained below using Figure 14. In Figure 14, the downstream passage 113 of the upstream passage 112 within the fuel passage 15 is shown with shading.

[0097] Here, the area over which the enlarged diameter portion 42 of the stopper 40 receives pressure in the axial direction is defined as the pressure-receiving area S11, the area over which the tip valve portion 22 of the needle valve 20 receives pressure in the axial direction is defined as the pressure-receiving area S12, and the area over which the bellows 50 receives pressure in the axial direction is defined as the pressure-receiving area S13. Furthermore, the pressure in the upstream passage 112 (upstream pressure) is defined as P1, the pressure in the downstream passage 113 (downstream pressure) is defined as P2, and the set load of the spring 27 is defined as Fs. In this case, the valve opening force F1 generated at the tip valve portion 22 of the needle valve 20 is expressed by the following equation (1). And, as shown in equation (2), it is preferable that the valve opening force F1 be smaller than the set load Fs of the spring 27. F1 = (P1 - P2)S11 + P2(S12 - S13) ... (1) F1 < Fs ... (2) The pressure-receiving area S12 at the tip valve portion 22 of the needle valve 20 and the pressure-receiving area S13 at the bellows 50 should be S12 = S13 or S12 > S13. However, S12 < S13 is also acceptable.

[0098] In the stopper 40, the configuration of the enlarged diameter portion 42 may be changed as shown in Figures 15 and 16. Figure 16 is a cross-sectional view taken along line 16-16 of Figure 15.

[0099] The enlarged diameter portion 42 of the stopper 40 is provided with a plurality of communication holes 121 that communicate in the axial direction, allowing gas fuel to pass through these communication holes 121. In other words, the communication holes 121 form a "communication passage" that connects the upstream passage 112 and the downstream passage 113. The opening shape of each communication hole 121 is circular. However, the opening shape of each communication hole 121 may be a polygon such as a square or hexagon, in addition to a circle. In the configuration of Figure 15, the upstream passage 112 and the downstream passage 113 are connected through an annular communication passage 111 between the enlarged diameter portion 42 and the housing 11, and also through a plurality of communication holes 121 formed in the enlarged diameter portion 42. Each communication hole 121 is a constricted portion that causes a pressure drop due to the constriction.

[0100] In the fuel injection valve 10, when the needle valve 20 is opened and gas fuel is injected due to the energization of the solenoid, the gas fuel flows through the communication passage 111 and the multiple communication holes 121 outside the enlarged diameter portion 42 of the stopper 40. At this time, a pressure difference is created due to the pressure loss that occurs when the gas fuel passes through the communication passage 111 and the communication holes 121, resulting in a high pressure in the upstream passage 112 and a low pressure in the downstream passage 113. This pressure difference provides an opening assist, which helps lift the needle valve 20 to the open side.

[0101] However, the stopper 40 may be provided in a state in which the enlarged diameter portion 42 slides against the inner circumferential surface of the housing. In this configuration, the communication passage is formed only by the communication holes 121 of the stopper 40.

[0102] In the enlarged diameter portion 42, the multiple communication holes 121 are evenly distributed in the circumferential direction centered on the axis of the needle valve 20. Specifically, the multiple communication holes 121 are arranged at predetermined equal angular intervals in the circumferential direction. For example, in a configuration with four communication holes 121, each communication hole 121 is arranged such that the circumferential angular interval from its center point is 90 degrees, and in a configuration with six communication holes 121, each communication hole 121 is arranged such that the circumferential angular interval from its center point is 60 degrees.

[0103] Furthermore, if a communication hole 121 is provided in the enlarged diameter portion 42 of the stopper 40, the area in the enlarged diameter portion 42 that receives axial pressure from the upstream passage 112 becomes smaller. Therefore, the pressure-receiving area S11 described above should take into account the reduction in the pressure-receiving area due to the communication hole 121.

[0104] In the configuration of Figure 15, it is preferable that it has the same configuration as in Figure 11, as follows: - The pressure-receiving area S11 of the enlarged diameter portion 42 of the stopper 40 that receives pressure axially from the upstream passage 112 (however, the area of ​​the enlarged diameter portion 42 excluding the communication hole 121) and the pressure-receiving area S12 of the tip valve portion 22 that receives pressure axially from the downstream passage 113 are in the relationship S11 > S12. - When the stopper 40 operates together with the opening operation of the needle valve 20, the opening area of ​​the communication passage 111 remains constant regardless of the lift amount of the needle valve 20. - In the flow direction in which the gas fuel flows from the upstream to the downstream side, the opening area at the point where the gas fuel passes through the enlarged diameter portion 42 (i.e., the total opening area of ​​the communication passage 111 and the communication hole 121) is the smallest among the gas fuel path up to the outlet 17a of the nozzle 17, excluding the opening area of ​​the nozzle outlet. - The combined opening area of ​​the communication passage 111 and the communication hole 121 is larger than the opening area of ​​the outlet 17a of the nozzle 17 when the needle valve 20 is in the full-lift state.

[0105] According to the third embodiment described above, in addition to the effects of the previously described embodiments, the following effects are achieved.

[0106] The fuel passage 15 of the fuel injection valve 10 is divided into an upstream passage 112 and a downstream passage 113 by a stopper 40, and these two passages are connected by a connecting passage 111 formed by the stopper 40. When the needle valve 20 opens, a pressure difference is created, with the upstream passage 112 at high pressure and the downstream passage 113 at low pressure. In this case, when the needle valve 20 opens, the pressure difference between the upstream passage 112 and the downstream passage 113 assists in opening the needle valve 20. This allows the needle valve 20 to open properly in the fuel injection valve 10, and consequently, enables proper fuel injection.

[0107] The enlarged diameter portion 42 of the stopper 40 forms a connecting passage 111 or a connecting hole 121, with the upstream side of the enlarged diameter portion 42 designated as the upstream passage 112 and the downstream side designated as the downstream passage 113. The enlarged diameter portion 42 of the stopper 40 is positioned at an intermediate axial position within the fuel passage 15 of the housing 11, and the enlarged diameter portion 42 allows the fuel passage 15 to be easily divided into the upstream passage 112 and the downstream passage 113. In this case, the pressure loss of the gaseous fuel as it passes through the enlarged diameter portion 42 of the stopper 40 can create a desired differential pressure within the fuel passage 15.

[0108] The stopper 40 is configured such that the pressure-receiving area S11, which receives axial pressure from the upstream passage 112 in the enlarged diameter portion 42, and the pressure-receiving area S12, which receives axial pressure from the downstream passage 113 in the tip valve portion 22, are in the relationship S11 > S12. In this case, by making the enlarged diameter portion 42, which receives high pressure, larger than the tip valve portion 22, which receives low pressure, the opening force of the needle valve 20 can be appropriately generated in the axial direction.

[0109] The stopper 40 is configured such that a communication passage 111 is formed by a communication hole 121 that communicates in the axial direction within the enlarged diameter portion 42 (configuration shown in Figure 15). In this case, a differential pressure can be generated on the upstream and downstream sides of the enlarged diameter portion 42 of the stopper 40, while increasing the flow rate of gas fuel passing through the enlarged diameter portion 42 in the axial direction.

[0110] The stopper 40 operates in conjunction with the opening operation of the needle valve 20, and the opening area of ​​the communication passage 111 remains constant regardless of the lift amount of the needle valve 20. As a result, there is no fluctuation in the opening force when the needle valve 20 moves to the full lift position, and stable needle valve opening operation can be achieved.

[0111] The opening area in the flow direction for gas fuel, where it flows from upstream to downstream, is configured such that the opening area of ​​the connecting passage 111 is the smallest among the gas fuel path up to the outlet 17a of the nozzle 17, excluding the opening area of ​​the nozzle outlet. This allows the connecting passage 111 formed by the stopper 40 to appropriately generate the desired differential pressure.

[0112] The opening area of ​​the communication passage 111, or the total opening area including the communication hole 121, is configured to be larger than the opening area at the outlet 17a of the injection hole 17 when the needle valve 20 is in the fully lifted state. This makes it possible to narrow the opening area of ​​the gas fuel path to generate differential pressure in the communication passage 111 or communication hole 121 upstream of the outlet 17a of the injection hole 17, while suppressing a decrease in the injection amount.

[0113] The communication passages 111 or communication holes 121 are provided evenly in the circumferential direction centered on the axis of the needle valve 20. This allows the pressure load to be applied evenly in the axial direction to the stopper 40, thereby suppressing the tilting of the needle valve 20.

[0114] (Fourth Embodiment) In this embodiment, unlike the third embodiment described above, the fuel injection valve 10 is configured such that the fuel passage 15 is divided into an upstream passage 112 and a downstream passage 113 by the cylindrical portion 41 of the stopper 40. Figure 17 is a cross-sectional view showing the configuration of this embodiment. In Figure 17, the downstream passage 113 of the fuel passage 15 is shown with shading.

[0115] In the fuel injection valve 10 shown in Figure 17, the communication holes 43 formed in the axially extending cylindrical portion 41 of the stopper 40 have a smaller opening area compared to the configurations in Figures 1 and 6. In this embodiment, the fuel passage 15 is divided into an upstream passage 112 and a downstream passage 113 by the cylindrical portion 41 of the stopper 40. That is, the upstream side of the cylindrical portion 41 in the fuel passage 15 is the upstream passage 112, and the downstream side of the cylindrical portion 41 is the downstream passage 113. The multiple communication holes 43 of the cylindrical portion 41 form a "communication passage" that connects the upstream passage 112 and the downstream passage 113. Each communication hole 43 is a throttling portion that causes a pressure drop due to throttling.

[0116] In the fuel injection valve 10, when the needle valve 20 opens and is lifted due to the energization of the solenoid, gaseous fuel flows downstream through each communication hole 43 of the cylindrical portion 41 of the stopper 40. At this time, the pressure loss that occurs when the gaseous fuel passes through the communication holes 43 creates a differential pressure, resulting in a lower pressure in the downstream passage 113 compared to the upstream passage 112. This differential pressure provides an opening assist, which helps lift the needle valve 20 to the open side. In this embodiment, the passage between the enlarged diameter portion 42 of the stopper 40 and the housing 11 has an opening area that does not cause a differential pressure (pressure drop), and the pressure is the same upstream and downstream of the enlarged diameter portion 42 within the fuel passage 15.

[0117] As shown in Figure 18, the cylindrical portion 41 of the stopper 40 is preferably provided with multiple communication holes 43 in the circumferential and axial directions. By providing multiple communication holes 43 in the circumferential and axial directions of the cylindrical portion 41, the opening area of ​​the communication holes 43 is narrowed to generate differential pressure, while suppressing a decrease in the injection volume.

[0118] In the stopper 40, if S21 is the pressure-receiving area that receives axial pressure from the upstream passage 112 radially inward from the outer circumferential surface of the cylindrical portion 41, and S22 is the pressure-receiving area that receives axial pressure from the downstream passage 113 at the tip valve portion 22 of the needle valve 20, then the relationship between S21 and S22 is S21 > S22.

[0119] In the configuration shown in Figure 17, the range in which the pressure in the upstream passage 112 acts axially on the stopper 40 is defined by the outer diameter of the cylindrical portion 41, and the pressure-receiving area S21 on the stopper 40 is defined by the outer diameter of the cylindrical portion 41. Therefore, when comparing the pressure-receiving area S21 on the stopper 40 side with the pressure-receiving area S22 on the needle valve 20 side, the pressure-receiving area S21 is preferably calculated as "S21 = π × D43^2 / 4" based on the outer diameter D43 of the cylindrical portion 41. Similarly, the pressure-receiving area S22 is preferably calculated as "S22 = π × D42^2 / 4" based on the seat diameter D42 of the tip valve portion 22. The seat diameter D42 of the tip valve portion 22 is, as explained in Figure 13, for example, the diameter of the part that contacts the tapered seat portion 14a.

[0120] According to the relationship S21 > S22, the range in the stopper 40 that receives high pressure is larger than the range in the tip valve portion 22 of the needle valve 20 that receives low pressure. Therefore, this configuration is suitable for increasing the opening force of the needle valve 20 in the axial direction.

[0121] In the fuel injection valve 10 shown in Figure 17, the opening area in the flow direction for gaseous fuel to flow from upstream to downstream is preferably the smallest opening area of ​​the communication holes 43 in the gaseous fuel path from the downstream side of the fixed core 31 (see Figure 6) to the outlet 17a of the injection hole 17, excluding the opening area of ​​the outlet 17a.

[0122] Furthermore, the total opening area of ​​the communication holes 43 is preferably larger than the opening area of ​​the needle valve 20 in the fully lifted state at the outlet 17a of the injection hole 17. This suppresses a decrease in the injection amount while narrowing the opening area of ​​the gas fuel path in the communication passage 111 upstream of the outlet 17a of the injection hole 17 in order to generate differential pressure.

[0123] According to the fourth embodiment described above, in addition to the effects of the embodiments described above, the following effects are achieved.

[0124] A communication hole 43 is provided in the cylindrical portion 41 of the stopper 40, and the upstream side of the communication hole 43 in the cylindrical portion 41 is the upstream passage 112, and the downstream side of the communication hole 43 in the cylindrical portion 41 is the downstream passage 113. This creates a differential pressure within the fuel passage 15, with high pressure on the upstream side and low pressure on the downstream side, thereby effectively achieving the desired valve opening assist.

[0125] In the stopper 40, the pressure-receiving area S21, which receives axial pressure from the upstream passage 112 radially inward from the outer circumferential surface of the cylindrical portion 41, and the pressure-receiving area S22, which receives axial pressure from the downstream passage 113 in the tip valve portion 22, are configured such that S21 > S22. In this case, by increasing the diameter of the cylindrical portion 41 that receives high pressure in the stopper 40 compared to the tip valve portion 22 that receives low pressure, the opening force of the needle valve 20 can be appropriately generated in the axial direction.

[0126] (Fifth Embodiment) Next, the fuel injector 200 of the fifth embodiment will be described. In this embodiment, the difference from the above embodiments is that the fuel injector 200 is configured not to have a stopper 40. Furthermore, within the housing 11 of the fuel injector 200, a differential pressure is generated between the upstream and downstream sides of the fuel passage 15 by the needle valve 210 or a plate-shaped ring member fixed to the needle valve 210, and this differential pressure assists in opening the needle valve 210.

[0127] Incidentally, a known prior art document for a gas fuel injection valve having an opening assist structure is German Patent Application Publication No. 102021209887. In this prior art document, the gas fuel injection valve is configured to include a throttle mechanism fixed within the injector housing, and the throttle mechanism generates negative pressure in a control chamber provided within the guide housing, thereby assisting in the opening of the needle valve.

[0128] However, the gas fuel injection valves described in the aforementioned prior art raise concerns about disadvantages such as increased size due to the inclusion of a throttling mechanism. Therefore, there is room for technical improvement.

[0129] The fuel injector 200 of this embodiment, like the third and fourth embodiments, is designed to ensure that the needle valve opens properly even when a back pressure acting as a closing load is applied to the tip valve portion of the needle valve from the axially outer side, which is the combustion chamber side, in a direct injection type gas fuel injector.

[0130] Figure 19 is a cross-sectional view showing the configuration of the fuel injector 200 near the axial tip. In the fuel injector 200 shown in Figure 19, components that are the same as those described in Figures 1 and 6 are given the same component numbers.

[0131] In the fuel injection valve 200 shown in Figure 19, the configuration of the needle valve 210 has been partially modified. Specifically, the needle valve 210 has a shaft portion 211 that extends axially and is inserted into the injection hole 17, a tip valve portion 212 provided at one axial end (lower end) of the shaft portion 211, a flange-shaped enlarged diameter portion 213 provided at an intermediate axial position of the needle valve 210, and a connecting shaft portion 214 which extends from the enlarged diameter portion 213 to the electromagnetic drive portion 30. The shaft portion 211 has a sliding portion 215 that slides inside the injection hole 17. The sliding portion 215 is provided with a communication passage 215a that communicates in the axial direction. The needle valve 210 is capable of reciprocating in the axial direction with the sliding surface of the sliding portion 215 in contact with the inner circumferential surface of the injection hole 17.

[0132] In the needle valve 210, the enlarged diameter portion 23, located at an intermediate position in the axial direction of the needle valve 210, is expanded radially outward compared to the configurations in Figures 1 and 6. More specifically, the enlarged diameter portion 213 of the needle valve 210 is formed in two stages with different outer diameters in the axial direction, with a relatively smaller diameter portion 213a on the bellows 50 side (the side opposite the tip of the needle valve 210) and a relatively larger diameter portion 213b on the tip side of the needle valve 210. One end of the bellows 50 is fixed to the smaller diameter portion 213a, and the larger diameter portion 213b is in close proximity to the inner circumferential surface of the housing 11.

[0133] An annular gap is formed between the circular outer edge of the enlarged diameter portion 213 and the housing 11, and this gap serves as the connecting passage 221. In this case, the fuel passage 15 is divided into an upstream passage 222 and a downstream passage 223 by the enlarged diameter portion 213 of the needle valve 210. That is, in the fuel passage 15, the upstream side of the enlarged diameter portion 213 is the upstream passage 222, and the downstream side of the enlarged diameter portion 213 is the downstream passage 223. The connecting passage 221 is a throttling section that causes a pressure drop due to throttling.

[0134] In the enlarged diameter portion 213, the outer edge of the large diameter portion 213b is circular (perfect circle) concentric with the inner circumferential surface of the housing 11, and a communication passage 221 of the same width is formed around the entire circumference between the housing 11 and the large diameter portion 213b of the enlarged diameter portion 213. In this configuration, the communication passage 221 is provided with a uniform width in the circumferential direction centered on the axis of the needle valve 210.

[0135] In the fuel injection valve 200 having the configuration shown in Figure 19, when gas fuel is injected from the nozzle 17 by the lift of the needle valve 210 due to the energization of the solenoid, the gas fuel flows through the communication passage 221 outside the enlarged diameter portion 213 of the needle valve 210 (more specifically, outside the large diameter portion 213b). That is, as the needle valve 210 opens, the gas fuel flows from the upstream passage 222 to the downstream passage 223. At this time, the pressure loss that occurs when the gas fuel passes through the communication passage 221 creates a differential pressure, making the downstream passage 223 lower in pressure than the upstream passage 222. This differential pressure provides an opening assist, which helps lift the needle valve 210 to the opening side. In other words, the throttling effect that occurs when the gas fuel passes through the communication passage 221 creates a differential pressure between the upstream passage 222 and the downstream passage 223, and this differential pressure provides an opening assist for the needle valve 210.

[0136] When the needle valve 210 opens, it is desirable that the opening area of ​​the communication passage 221 remains constant regardless of the amount of lift of the needle valve 210. In this embodiment, the cylindrical portion (body 13) on the radially outer side of the enlarged diameter portion 213 in the housing 11 is cylindrical with the same diameter in the axial direction, and the enlarged diameter portion 213 reciprocates in the axial direction along the inner circumferential surface of the cylindrical portion. In this case, the opening area of ​​the communication passage 221 is kept constant regardless of the lift of the needle valve 210. Therefore, there is no fluctuation in the opening force when the needle valve 210 operates to the full lift position.

[0137] When the pressure-receiving area that receives axial pressure from the upstream passage 222 at the enlarged diameter portion 213 of the needle valve 210 is S31, and the pressure-receiving area that receives axial pressure from the downstream passage 223 at the tip valve portion 212 of the needle valve 210 is S32, the relationship between S31 and S32 is S31 > S32.

[0138] When comparing the pressure-receiving area S31 on the enlarged diameter portion 213 side of the needle valve 210 with the pressure-receiving area S32 on the tip valve portion 212 side of the needle valve 210, the pressure-receiving area S31 is preferably calculated as "S31 = π × D51^2 / 4" based on the outer diameter dimension D51 of the enlarged diameter portion 213. Similarly, the pressure-receiving area S32 is preferably calculated as "S32 = π × D52^2 / 4" based on the seat diameter dimension D52 of the tip valve portion 212. Note that the seat diameter dimension D52 of the tip valve portion 212 is, for example, the diameter of the part that contacts the tapered seat portion 14a, as explained in Figure 13.

[0139] According to the relationship S31 > S32, in the needle valve 210, the enlarged diameter portion 213 that receives high pressure is larger than the tip valve portion 212 that receives low pressure. Therefore, this configuration is suitable for increasing the opening force of the needle valve 210 in the axial direction.

[0140] In the fuel injection valve 200 shown in Figure 19, the opening area in the flow direction for gaseous fuel flowing from upstream to downstream is smallest in the communication passage 221, which is downstream of the fixed core 31 and within the gaseous fuel path up to the outlet 17a of the injection hole 17, excluding the opening area of ​​the outlet 17a. The opening area of ​​the outlet 17a is the opening area of ​​the injection valve tip when the needle valve 210 is in the full-lift state.

[0141] Furthermore, the opening area of ​​the communication passage 221 is larger than the opening area of ​​the needle valve 210 in the fully lifted state at the outlet 17a of the injection hole 17. As a result, in the communication passage 221 upstream of the outlet 17a of the injection hole 17, the opening area of ​​the gas fuel path is narrowed to generate differential pressure, while suppressing a decrease in the injection amount.

[0142] Specifically, the opening area of ​​the communication passage 221 (the opening area of ​​the throttling section) should be approximately 120 to 300% of the opening area of ​​the nozzle outlet when the needle valve 210 is in the fully lifted state. More preferably, the opening area of ​​the communication passage 221 should be approximately 150 to 250% of the opening area of ​​the nozzle outlet when the needle valve 210 is in the fully lifted state.

[0143] As shown in Figure 20, the large-diameter portion 213b of the enlarged diameter portion 213 is provided with a plurality of communication holes 226 that communicate in the axial direction, and gas fuel may be able to pass through these communication holes 226. In this case, the communication holes 226 form a "communication passage" that connects the upstream passage 222 and the downstream passage 223. The opening shape of each communication hole 226 is circular. However, the opening shape of each communication hole 226 may be a polygon other than a circle, such as a square or hexagon. In the configuration of Figure 20, the upstream passage 222 and the downstream passage 223 are connected through an annular communication passage 221 between the large-diameter portion 213b of the enlarged diameter portion 213 and the housing 11, and are also connected through a plurality of communication holes 226 formed in the large-diameter portion 213b of the enlarged diameter portion 213.

[0144] In the fuel injection valve 200 shown in Figure 20, the opening area in the flow direction for gas fuel flowing from upstream to downstream is smallest at the point where the gas fuel passes through the enlarged diameter section 213 (i.e., the total opening area of ​​the communication passage 221 and the communication hole 226), excluding the opening area of ​​the outlet 17a, within the gas fuel path downstream of the fixed core 31 and up to the outlet 17a of the injection hole 17.

[0145] Furthermore, the total opening area of ​​the communication passage 221 and the communication hole 226 is larger than the opening area of ​​the outlet 17a of the nozzle 17 when the needle valve 210 is in the fully lifted state.

[0146] In the needle valve 210, the configuration of the enlarged diameter portion 213 may be changed as shown in Figure 21.

[0147] In Figure 21, a ring member 231 is fixed to the outer circumference of the enlarged diameter portion 213 of the needle valve 210. The ring member 231 is a plate-shaped annular member that extends radially outward from the shaft portion 211. As a result, an annular gap is formed between the outer edge of the ring member 231 fixed to the needle valve 210 and the housing 11, and this gap forms the communication passage 221. The ring member 231 may be fixed by, for example, press-fitting, welding, brazing, adhesion, or screw fastening. In this case, the fuel passage 15 is divided into an upstream passage 222 and a downstream passage 223 by the ring member 231. That is, in the fuel passage 15, the upstream side of the ring member 231 is the upstream passage 222, and the downstream side of the ring member 231 is the downstream passage 223. In this configuration, the ring member 231 corresponds to the "enlarged diameter portion".

[0148] In Figure 21, the diameter of the portion (enlarged diameter portion 213) where the ring member 231 is fixed in the needle valve 210 is D61, and the diameter of the inner circumferential surface of the injection hole 17 in the nozzle 14 is D62. The relationship between these diameters D61 and D62 is D61 < D62. In this case, even if the needle valve 210 is configured such that an outward-opening tip valve portion 212 is provided on one axial side of the injection hole 17, and an enlarged diameter portion (ring member 231) for generating differential pressure is provided on the other axial side of the injection hole 17, the needle valve 210 can be assembled without interfering with the nozzle 14.

[0149] According to the fifth embodiment described above, the following effects are achieved.

[0150] The fuel passage 15 of the fuel injection valve 200 is divided into an upstream passage 222 and a downstream passage 223 by an enlarged diameter portion 213 of the needle valve 210, and these two passages are connected by a connecting passage 221 formed by the enlarged diameter portion 213. When the needle valve 210 opens, a pressure difference is created, with the upstream passage 222 being at high pressure and the downstream passage 223 being at low pressure. In this case, when the needle valve 210 opens, the pressure difference between the upstream passage 222 and the downstream passage 223 assists in opening the needle valve 210. This allows the needle valve 210 to open properly in the fuel injection valve 200, and consequently, proper fuel injection can be performed.

[0151] The needle valve 210 is configured such that the pressure-receiving area S31 in the enlarged diameter portion 213, which receives pressure axially from the upstream passage 222, and the pressure-receiving area S32 in the tip valve portion 212, which receives pressure axially from the downstream passage 223, are in the relationship S31 > S32. In this case, by making the enlarged diameter portion 213, which receives high pressure, larger than the tip valve portion 212, which receives low pressure, the opening force of the needle valve 210 can be appropriately generated in the axial direction.

[0152] The needle valve 210 is configured such that the opening area of ​​the communication passage 221 remains constant regardless of the lift amount of the needle valve 210 when it opens. As a result, there is no fluctuation in the opening force when the needle valve 210 moves to the full lift position, and stable needle valve opening operation can be achieved.

[0153] The needle valve 210 is configured such that a communication passage is formed by a communication hole 226 that communicates axially in the enlarged diameter portion 213. In this configuration, a differential pressure can be generated on the upstream and downstream sides of the enlarged diameter portion 213 of the needle valve 210, while increasing the flow rate of gas fuel passing through the enlarged diameter portion 213 in the axial direction.

[0154] The opening area in the flow direction for gas fuel, where it flows from upstream to downstream, is configured such that the opening area of ​​the communication passage 221 is the smallest among the gas fuel path up to the outlet 17a of the nozzle 17, excluding the opening area of ​​the nozzle outlet. This allows the communication passage 221 formed by the needle valve 210 to appropriately generate the desired differential pressure.

[0155] The opening area of ​​the communication passage 221 is configured to be larger than the opening area of ​​the needle valve 210 in the fully lifted state at the outlet 17a of the injection hole 17. This makes it possible to narrow the opening area of ​​the gas fuel path in the communication passage 221 upstream of the outlet 17a of the injection hole 17 in order to generate differential pressure, while suppressing a decrease in the injection amount.

[0156] The needle valve 210 is configured to have a ring member 231 fixed to it as an enlarged diameter portion, extending radially outward from the shaft portion 211 (configuration shown in Figure 21). This allows the differential pressure generated by the ring member 231 to assist in opening the needle valve 210 when it is opened. Furthermore, the ring member 231 as the enlarged diameter portion of the needle valve 210 is a separate structure, and the diameter of the part to which the ring member 231 is fixed is made smaller than the diameter of the inner circumferential surface of the injection hole 17. This improves the ease of assembly of the needle valve 210 in the fuel injection valve 200.

[0157] In the needle valve 210, the base end side opposite to the tip valve portion 212 is surrounded by a bellows 50, and the bellows 50 is provided as an isolation member that separates the fuel passage 15 from the space 51 surrounding the needle valve 210 within the housing 11. In this case, the bellows 50 can reduce the set load of the spring 27, and consequently reduce the required opening force of the needle valve 210.

[0158] According to the fifth embodiment described above, the following technical features are extracted. [Feature 1] A gas fuel injection valve (200) for injecting gaseous fuel, comprising: a cylindrical body portion (11) having a fuel passage (15) inside and a nozzle (14) provided at its tip having a nozzle hole (17); an outward-opening needle valve (210) provided inside the body portion, reciprocating in the axial direction, and closing the nozzle hole from the outside; a biasing member (27) that biases the needle valve in the direction of closing the nozzle hole; and a drive unit (30) that opens the needle valve against the biasing force of the biasing member, wherein the needle valve has a shaft portion (211) extending in the axial direction and enlarged diameter portions (213, 231) that are larger in diameter than the shaft portion. [Feature 2] The fuel passage is divided into an upstream passage (222) and a downstream passage (223) by the enlarged diameter portion of the needle valve, and the upstream and downstream passages are connected by a connecting passage (221, 226) formed by the enlarged diameter portion, and when the needle valve is opened, the gas fuel passing through the connecting passage generates a differential pressure such that the upstream passage is at high pressure and the downstream passage is at low pressure, in the gas fuel injection valve according to Feature 1. The needle valve has a tip valve portion (212) that closes the injection hole by contacting the seat portion of the nozzle, and when the enlarged diameter portion of the needle valve receives pressure in the axial direction from the upstream passage as S31, and the tip valve portion receives pressure in the axial direction from the downstream passage as S32, the relationship between S31 and S32 is S31 > S32, in the gas fuel injection valve according to Feature 1. [Feature 3] The gas fuel injection valve according to Feature 1 or 2, wherein when the needle valve opens, the opening area of ​​the communication passage is constant regardless of the lift amount of the needle valve. [Feature 4] The gas fuel injection valve according to any one of Features 1 to 3, wherein the communication passage is formed by a communication hole (226) that communicates axially in the enlarged diameter portion of the needle valve. [Feature 5] The gas fuel injection valve according to any one of Features 1 to 4, wherein the opening area in the flow direction for gas fuel flowing from the upstream side to the downstream side is such that the opening area of ​​the communication passage is the smallest among the gas fuel path up to the outlet of the injection hole, excluding the opening area of ​​the outlet.[Feature 6] The gas fuel injection valve according to any one of Features 1 to 5, wherein the opening area of ​​the communication passage is larger than the opening area of ​​the needle valve in the fully lifted state at the outlet of the nozzle. [Feature 7] The gas fuel injection valve according to any one of Features 1 to 6, wherein the needle valve has a ring member (231) fixed as the enlarged diameter portion, which extends radially outward from the shaft portion, and the diameter of the portion of the needle valve to which the ring member is fixed is smaller than the diameter of the inner circumferential surface of the nozzle. [Feature 8] The gas fuel injection valve according to any one of Features 1 to 7, wherein the needle valve has a tip valve portion (212) at one axial end for opening and closing the nozzle, and the base end on the opposite side from the tip valve portion is surrounded by a cylindrical bellows (50) that can expand and contract axially as the needle valve moves, and the bellows is provided as an isolation member that isolates the fuel passage and the space portion (51) surrounding the needle valve within the main body.

[0159] (Other Embodiments) The above embodiments may be modified as follows, for example.

[0160] The needle valve 20 may be composed of two members that are axially separable and can move independently of each other. Specifically, in the needle valve 20, the tip portion is configured as a valve member having a shaft portion 21, a tip valve portion 22, and an enlarged diameter portion 23, while the base portion is configured as a push rod interposed between the enlarged diameter portion 23 on the valve member side and the movable core 32, and separable from the valve member. In this configuration, when the fuel injection valve 10 opens due to the generation of a driving magnetic flux, the needle valve 20 is pushed to the open side by the push rod, and when the valve closes due to the disappearance of the driving magnetic flux, the push rod moves independently of the needle valve 20. Therefore, the collision load when the needle valve 20 seats on the valve seat portion on the main body side is reduced.

[0161] In the second embodiment described above, the shim 71 in the fuel injection valve 10A is configured to be approximately C-shaped in plan view, but this configuration may be changed. For example, the shim 71 may be configured to be annular in plan view and to be divisible into multiple parts in the circumferential direction. Specifically, the shim 71 may be composed of two semicircular members, and these two semicircular members may be joined together to form a circular shim 71.

[0162] In the above embodiments, the fuel injection valve 10 is a balance valve structure using a bellows 50, but this may be changed to a configuration that does not use a bellows 50.

[0163] In the third embodiment, the enlarged diameter portion 42 of the stopper 40 may be as shown in Figure 22. Figures 22(a) and (b) show the cross-sectional shape of the enlarged diameter portion 42. In Figures 22(a) and (b), the inner circumferential surface of the housing 11 and the seat diameter position 22X of the tip valve portion 22 are shown by dashed lines.

[0164] In Figure 22(a), flat sections 42a are formed at predetermined intervals on the circular outer edge of the enlarged diameter section 42. In this case, the radial dimension from the axis of the enlarged diameter section 42 to the flat sections 42a should be larger than the diameter of the seat diameter position 22X. Also, in Figure 22(b), recesses 42b are formed at predetermined intervals on the circular outer edge of the enlarged diameter section 42. In this case, the radial dimension to the bottom of the recesses 42b in the enlarged diameter section 42 should be smaller than the diameter of the seat diameter position 22X. In the configurations of Figures 22(a) and (b) above, the space between the enlarged diameter section 42 and the housing 11 is a connecting passage 111 for creating a differential pressure between the upstream passage 112 and the downstream passage 113.

[0165] In the fifth embodiment, the same configuration as in Figures 22(a) and (b) above can also be applied to the external shape of the enlarged diameter portion 213 of the needle valve 210.

[0166] The technical concept extracted from the above-described embodiment is described below. [Configuration 1] A gas fuel injection valve (10) for injecting gas fuel, comprising: a cylindrical body (11) having a fuel passage (15) inside and a nozzle (14) provided at its tip having a nozzle hole (17); an outward-opening needle valve (20) provided within the body, reciprocating in the axial direction, and closing the nozzle hole from the outside; a biasing member (27) that biases the needle valve in the direction of closing the nozzle hole; a fixed core (31) fixed to the body; a movable core (32) that is attracted to the fixed core when a driving magnetic flux is generated and opens the needle valve against the biasing force of the biasing member; and a cylindrical stopper (40) through which the needle valve is inserted in the axial direction, reciprocating in the axial direction integrally with the needle valve, and provided so that its axial end on the tip side faces the nozzle at a position away from it. [Configuration 2] The gas fuel injection valve according to Configuration 1, wherein the stopper contacts the nozzle after the movable core starts moving due to the driving magnetic flux, but before the movable core contacts the fixed core, and the maximum lift amount of the needle valve is restricted by the contact of the stopper. [Configuration 2] The gas fuel injection valve according to Configuration 1, wherein the nozzle hole and the hollow portion (41a) of the cylindrical portion (41) of the stopper are in axial communication, the needle valve is inserted through the nozzle hole and the hollow portion, and when the opening dimension of the nozzle hole is D11 and the inner diameter dimension of the cylindrical portion is D12, the relationship between D11 and D12 is D11 ≤ D12. [Configuration 3] The gas fuel injection valve according to Configuration 1 or 2, wherein the inner circumference of the cylindrical portion (41) of the stopper has an annular passage (45) between it and the shaft portion (21) of the needle valve through which gas fuel passes, and the cylindrical portion is provided with a communication hole (43) for gas fuel to flow into the annular passage. [Configuration 4] The gas fuel injection valve according to Configuration 3, wherein when the cross-sectional area of ​​the annular passage is S1 and the total opening area of ​​the communication holes in the stopper is S2, S1 and S2 satisfy the relationship S1 ≤ S2. [Configuration 5] The gas fuel injection valve according to any one of Configurations 1 to 4, wherein the material of the stopper has the same coefficient of linear expansion as the needle valve and the nozzle.[Configuration 6] The needle valve has a tip valve portion (22) on one axial end for opening and closing the injection hole, and the other axial end is capable of contacting the movable core, and is provided with a cylindrical bellows (50) that surrounds the portion of the needle valve from an axial intermediate position to the axial end on the movable core side and is capable of expanding and contracting in the axial direction as the needle valve moves, the bellows is provided as an isolation member that separates the fuel passage and the space portion (51) surrounding the needle valve within the main body, and the axial stopper contact position in the nozzle where the stopper contacts is on the injection valve tip side than the position of the fixed portion of the bellows relative to the needle valve, the gas fuel injection valve according to any one of Configurations 1 to 5. [Configuration 7] A gas fuel injection valve assembled to an engine body, wherein the outer circumference of the tip portion of the main body is reduced in diameter, and the reduced diameter portion forms the nozzle, the stepped axial end face formed by the reduction in diameter of the main body is brought into contact with the engine body, and the gas fuel injection valve is assembled to the engine body with a predetermined tightening force applied in the axial direction from the base end side opposite to the tip portion of the main body, and the axial stopper contact position in which the stopper contacts the nozzle is located closer to the injection valve tip than the position of the stepped axial end face. [Configuration 8] The needle valve has a shaft portion (21) extending in the axial direction and an enlarged diameter portion (23) that is larger in diameter than the shaft portion, the stopper is fixable to the enlarged diameter portion with the shaft portion of the needle valve inserted through it, and when the outer diameter dimension of the enlarged diameter portion of the needle valve is α1 and the inner diameter dimension of the stopper is α2, the relationship between these dimensions α1 and α2 is α1 ≤ α2, the gas fuel injection valve according to any one of Configurations 1 to 7.[Configuration 9] The needle valve has a shaft portion (21) extending in the axial direction and an enlarged diameter portion (23) that is larger in diameter than the shaft portion, and a shim (71) is provided between the enlarged diameter portion of the needle valve and the axial end face of the stopper in the axial direction so as to surround the shaft portion, and the shim has an inner diameter dimension β1 that is smaller than the outer diameter dimension β2 of the enlarged diameter portion, and an outer diameter dimension β3 that is larger than the inner diameter dimension β4 of the stopper, and the relationship between the outer diameter dimension β2 of the enlarged diameter portion and the inner diameter dimension β4 of the stopper is β2 < β4, as described in any configuration 1 to 7. [Configuration 10] The axial end face of the stopper is provided with an assembly recess (44) for assembling the shim, and the axial depth dimension of the assembly recess is smaller than the gap dimension between the axial end faces of the stopper and the nozzle that face each other in the axial direction, as described in configuration 9. [Configuration 11] The fuel passage is divided into an upstream passage (112) and a downstream passage (113) by the stopper, and the upstream passage and the downstream passage are connected by a connecting passage (111) formed by the stopper, and when the needle valve is opened, the gas fuel passing through the connecting passage generates a differential pressure such that the upstream passage is at high pressure and the downstream passage is at low pressure, as described in any configuration 1 to 10. [Configuration 12] The gas fuel injection valve according to configuration 11, wherein the stopper has a cylindrical portion (41) extending in the axial direction and an enlarged diameter portion (42) provided on one end of the cylindrical portion and extended radially outward from the cylindrical portion, and the connecting passage is formed by the enlarged diameter portion, the upstream side of the enlarged diameter portion is the upstream passage, and the downstream side of the enlarged diameter portion is the downstream passage. [Configuration 13] The gas fuel injection valve according to Configuration 12, wherein the needle valve has a tip valve portion (22) that closes the injection hole by contacting the seat portion of the nozzle, and when the pressure-receiving area of ​​the enlarged diameter portion of the stopper that receives pressure in the axial direction from the upstream passage is S11, and the pressure-receiving area of ​​the tip valve portion that receives pressure in the axial direction from the downstream passage is S12, the relationship between S11 and S12 is S11 > S12.[Configuration 14] The gas fuel injection valve according to Configuration 12 or 13, wherein the communication passage is formed by a communication hole (121) that communicates axially in the enlarged diameter portion of the stopper. [Configuration 15] The gas fuel injection valve according to any one of Configurations 12 to 14, wherein when the stopper operates integrally with the opening operation of the needle valve, the opening area of ​​the communication passage is constant regardless of the lift amount of the needle valve. [Configuration 16] The gas fuel injection valve according to Configuration 11, wherein the stopper has a cylindrical portion (41) that extends axially, and the hollow portion (41a) of the cylindrical portion is a passage leading to the injection hole of the nozzle, and the cylindrical portion is provided with a communication hole (43) that allows gas fuel to flow into the hollow portion as the communication passage, the upstream side of the cylindrical portion from the communication hole is the upstream passage, and the downstream side of the cylindrical portion from the communication hole is the downstream passage. [Configuration 17] The needle valve has a tip valve portion (22) that closes the injection hole by contacting the seat portion of the nozzle, and when the pressure-receiving area that receives axial pressure from the upstream passage radially inward from the outer circumferential surface of the cylindrical portion of the stopper is S21, and the pressure-receiving area that receives axial pressure from the downstream passage of the tip valve portion is S22, then S21 and S22 have the relationship S21 > S22, as described in Configuration 16. [Configuration 18] The gas fuel injection valve according to any one of Configurations 11 to 17, wherein the opening area in the flow direction in which the gas fuel flows from the upstream side to the downstream side is such that the opening area of ​​the communication passage is the smallest among the gas fuel path up to the outlet of the injection hole, excluding the opening area of ​​the outlet. [Configuration 19] The gas fuel injection valve according to Configuration 18, wherein the opening area of ​​the communication passage is larger than the opening area of ​​the needle valve in the full-lift state at the outlet of the injection hole. [Configuration 20] The gas fuel injection valve according to any one of configurations 11 to 19, wherein the communication passages are evenly provided in the circumferential direction centered on the axis of the needle valve.

[0167] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A gas fuel injection valve (10) for injecting gaseous fuel, comprising: a cylindrical body (11) having a fuel passage (15) inside and a nozzle (14) at its tip having a nozzle hole (17); an outward-opening needle valve (20) provided within the body and reciprocating in the axial direction, which closes the nozzle hole from the outside; a biasing member (27) which biases the needle valve in the direction of closing the nozzle hole; a fixed core (31) fixed to the body; a movable core (32) which is attracted to the fixed core when a driving magnetic flux is generated and opens the needle valve against the biasing force of the biasing member; and a cylindrical stopper (40) through which the needle valve is inserted in the axial direction, which is reciprocating in the axial direction integrally with the needle valve, and which is provided so that its axial end at the tip is opposed to the nozzle at a position away from it. A gas fuel injection valve in which, after the movable core starts moving due to the driving magnetic flux, the stopper contacts the nozzle before the movable core contacts the fixed core, and the maximum lift amount of the needle valve is restricted by the contact of the stopper.

2. The gas fuel injection valve according to claim 1, wherein the nozzle's injection hole and the hollow portion (41a) of the cylindrical portion (41) of the stopper are in axial communication, the needle valve is inserted through the injection hole and the hollow portion, and when the opening dimension of the injection hole is D11 and the inner diameter dimension of the cylindrical portion is D12, the relationship between D11 and D12 is D11 ≤ D12.

3. The inner circumference of the cylindrical portion (41) of the stopper is an annular passage (45) through which gas fuel passes between it and the shaft portion (21) of the needle valve, and the cylindrical portion is provided with a communication hole (43) for allowing gas fuel to flow into the annular passage, as described in claim 1.

4. The gas fuel injection valve according to claim 3, wherein S1 is the cross-sectional area of ​​the annular passage and S2 is the total opening area of ​​the communication holes in the stopper, and S1 and S2 satisfy the relationship S1 ≤ S2.

5. The gas fuel injection valve according to claim 1, wherein the material of the stopper has the same coefficient of linear expansion as the needle valve and the nozzle.

6. The gas fuel injection valve according to any one of claims 1 to 5, wherein the needle valve has a tip valve portion (22) at one axial end for opening and closing the injection hole, and the other axial end is capable of contacting the movable core, and the needle valve is provided with a cylindrical bellows (50) that surrounds the portion of the needle valve from an axial intermediate position to the axial end on the movable core side and is capable of expanding and contracting in the axial direction as the needle valve moves, the bellows is provided as an isolation member that separates the fuel passage from the space portion (51) surrounding the needle valve within the main body, and the axial stopper contact position at the nozzle where the stopper contacts is located closer to the injection valve tip than the position of the fixed portion of the bellows relative to the needle valve.

7. A gas fuel injector assembled to an engine body, wherein the outer circumference of the tip portion of the main body is reduced in diameter, and the reduced diameter portion forms the nozzle, the stepped axial end face formed by the reduction in diameter of the main body is brought into contact with the engine body, and the gas fuel injector is assembled to the engine body with a predetermined tightening force applied in the axial direction from the base end side opposite to the tip portion of the main body, and the axial stopper contact position in which the stopper contacts the nozzle is located closer to the injector tip than the position of the stepped axial end face.

8. The gas fuel injection valve according to any one of claims 1 to 5, wherein the needle valve has a shaft portion (21) extending in the axial direction and an enlarged diameter portion (23) that is larger in diameter than the shaft portion, the stopper is fixable to the enlarged diameter portion with the shaft portion of the needle valve inserted through it, and when the outer diameter dimension of the enlarged diameter portion of the needle valve is α1 and the inner diameter dimension of the stopper is α2, the relationship between these dimensions α1 and α2 is α1 ≤ α2.

9. The gas fuel injection valve according to any one of claims 1 to 5, wherein the needle valve has a shaft portion (21) extending in the axial direction and an enlarged diameter portion (23) that is larger in diameter than the shaft portion, and a shim (71) is provided between the enlarged diameter portion of the needle valve and the axial end face of the stopper in the axial direction so as to surround the shaft portion, the shim has an inner diameter dimension β1 that is smaller than the outer diameter dimension β2 of the enlarged diameter portion and an outer diameter dimension β3 that is larger than the inner diameter dimension β4 of the stopper, and the relationship between the outer diameter dimension β2 of the enlarged diameter portion and the inner diameter dimension β4 of the stopper is β2 < β4.

10. The gas fuel injection valve according to claim 9, wherein the axial end face of the stopper is provided with an assembly recess (44) for assembling the shim, and the axial depth dimension of the assembly recess is smaller than the gap dimension between the axial end faces of the stopper and the nozzle that face each other in the axial direction.

11. The gas fuel injection valve according to claim 1, wherein the fuel passage is divided by the stopper into an upstream passage (112) and a downstream passage (113), and the upstream passage and the downstream passage are connected by a connecting passage (111) formed by the stopper, and when the needle valve is opened, the gas fuel passing through the connecting passage generates a differential pressure such that the upstream passage is at high pressure and the downstream passage is at low pressure.

12. The gas fuel injection valve according to claim 11, wherein the stopper has a cylindrical portion (41) extending in the axial direction and an enlarged diameter portion (42) provided on one end of the cylindrical portion and extending radially outward from the cylindrical portion, the enlarged diameter portion forming the communication passage, the upstream side of the enlarged diameter portion being the upstream passage, and the downstream side of the enlarged diameter portion being the downstream passage.

13. The gas fuel injection valve according to claim 12, wherein the needle valve has a tip valve portion (22) that closes the injection hole by contacting the seat portion of the nozzle, and when the enlarged diameter portion of the stopper receives pressure in the axial direction from the upstream passage as S11, and the pressure receiving area of ​​the tip valve portion receives pressure in the axial direction from the downstream passage as S12, the relationship between S11 and S12 is S11 > S12.

14. The gas fuel injection valve according to claim 12, wherein the communication passage is formed by a communication hole (121) that communicates in the axial direction in the enlarged diameter portion of the stopper.

15. The gas fuel injection valve according to claim 12, wherein when the stopper operates in conjunction with the opening operation of the needle valve, the opening area of ​​the communication passage remains constant regardless of the lift amount of the needle valve.

16. The gas fuel injection valve according to claim 11, wherein the stopper has a cylindrical portion (41) extending in the axial direction, the hollow portion (41a) of the cylindrical portion serves as a passage leading to the injection hole of the nozzle, the cylindrical portion is provided with a communication hole (43) for introducing gas fuel into the hollow portion as the communication passage, the upstream side of the cylindrical portion beyond the communication hole serves as the upstream passage, and the downstream side of the cylindrical portion beyond the communication hole serves as the downstream passage.

17. The gas fuel injection valve according to claim 16, wherein the needle valve has a tip valve portion (22) that closes the injection hole by contacting the seat portion of the nozzle, and when the pressure-receiving area of ​​the stopper that receives pressure axially from the upstream passage radially inward from the outer circumferential surface of the cylindrical portion is S21, and the pressure-receiving area of ​​the tip valve portion that receives pressure axially from the downstream passage is S22, the relationship between S21 and S22 is S21 > S22.

18. The gas fuel injection valve according to any one of claims 11 to 17, wherein the opening area in the flow direction for gas fuel to flow from upstream to downstream is such that the opening area of ​​the communication passage is the smallest among the gas fuel path up to the outlet of the injection hole, excluding the opening area of ​​the outlet.

19. The gas fuel injection valve according to claim 18, wherein the opening area of ​​the communication passage is larger than the opening area of ​​the needle valve in the fully lifted state at the outlet of the injection hole.

20. The gas fuel injection valve according to any one of claims 11 to 17, wherein the communication passages are evenly distributed in the circumferential direction with respect to the axis of the needle valve.

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