Gas fuel injection valve

Abstract

In this gas fuel injection valve (10), a partition part (33) that partitions a fuel passage into a first fuel passage (P1) on the upstream side and a second fuel passage (P2) on the downstream side is provided with a connection hole (34) for connecting these fuel passages. In a body, provided are a first opening / closing valve (13) that opens / closes the connection hole from the first fuel passage side, a second opening / closing valve (14) that opens / closes the connection hole from the second fuel passage side, and a seal member (27) that seals the circumference of the opening of the connection hole between the first opening / closing valve and the partition part. The first opening / closing valve is driven by a drive unit (25) to open. Meanwhile, the second opening / closing valve is configured to open in association with the pressure in the connection hole being higher than the biasing force of a biasing member (45) that biases the second opening / closing valve toward the valve-closing side, and to cause a gas fuel, which has flown out from the connection hole and has been adiabatically expanded in association with opening of the second opening / closing valve, to collide with extension parts (35, 38) extending downstream from the partition part to cool the extension parts.

Description

Gas fuel injection valve CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-127077, filed on August 3, 2023, the contents of which are incorporated herein by reference.

[0002] The disclosure herein relates to gas fuel injectors.

[0003] A known example of a gas fuel injection valve for use in a direct-injection gas engine is the gas metering valve described in Patent Document 1. In this gas metering valve, an actuator-driven valve member is provided with an elastomeric seal member to prevent gas fuel leakage. The valve member seal is positioned far away from the fuel outlet opening to prevent damage to the seal member due to heat and pressure generated during combustion in the gas engine. The gas metering valve also includes a check valve (passive on-off valve) between the actuator-driven valve member and the outlet opening, which opens in response to the pressure difference between the upstream and downstream sides. This prevents flames and combustion pressure in the combustion chamber from propagating to the seal member. This effectively protects the elastomeric seal member.

[0004] Special Publication No. 2023-513065

[0005] However, the technology described in Patent Document 1 increases the distance between the valve member provided with the sealing member and the check valve downstream, increasing the volume between these valve members and the check valve. This may result in poor closing response of the check valve when the upstream valve member closes, which could lead to gas leakage from the fuel injection valve and, ultimately, abnormal combustion in the gas engine. However, on the other hand, if the upstream valve member with a sealing function is installed too close to the check valve, there is a risk of damage to the sealing member of the valve member due to heat.

[0006] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a gas fuel injection valve that can protect a seal member while ensuring the injection performance of gas fuel.

[0007] The present disclosure relates to a gas fuel injection valve that directly injects gas fuel into a combustion chamber of an internal combustion engine, comprising: a cylindrical main body having a fuel passage therein and an injection hole at a tip end; the main body having a partition portion that partitions the fuel passage into a first fuel passage on an upstream side and a second fuel passage on a downstream side, the partition portion being provided with a communication hole that communicates the first fuel passage with the second fuel passage; and the main body is provided with a first on-off valve that opens and closes the communication hole from the first fuel passage side, a second on-off valve that opens and closes the communication hole from the second fuel passage side, and a seal member that seals the periphery of the opening of the communication hole between the first on-off valve and the partition portion; the first on-off valve is driven to open by a drive portion, while the second on-off valve is opened when the pressure in the communication hole becomes higher than the biasing force of a biasing member that biases the second on-off valve to a valve closing side, The gas fuel that flows out of the communication hole and adiabatically expands when the second on-off valve is opened is made to collide with an extension portion that extends downstream from the partition portion, thereby cooling the extension portion.

[0008] In the fuel injection valve having the above-described configuration, the cylindrical main body has a first fuel passage on the upstream side of the partition and a second fuel passage on the downstream side, and the first fuel passage and the second fuel passage are connected to each other through a communication hole. When the drive unit drives the first on-off valve to open, the communication hole is opened from the first fuel passage side. When the pressure in the communication hole increases due to the opening of the first on-off valve, the passive second on-off valve opens, and the communication hole is also opened on the second fuel passage side. When the communication holes are opened on the upstream and downstream sides, gas fuel is injected from the fuel injection valve. In this case, a seal member is provided between the first on-off valve and the partition, sealing the periphery of the opening of the communication hole. This improves gas sealing performance compared to a configuration in which the first on-off valve and the partition are in direct contact when the first on-off valve is closed.

[0009] Furthermore, when the gas fuel flows out of the communication hole upon opening of the second on-off valve, adiabatic expansion of the gas fuel occurs. The adiabatic expansion of the gas fuel cools the partition. Specifically, the adiabatic expansion of the gas fuel that flows out of the communication hole upon opening of the second on-off valve impacts the extension extending downstream from the partition, cooling the extension. The cooling of the extension further cools the partition. The cooling of the partition also cools the seal member located on the opposite side of the partition from the second on-off valve (the first on-off valve side) across the partition. Although the seal member is located relatively close to the second on-off valve, separated only by the partition, excessive temperature rise of the seal member is suppressed. Furthermore, because the upstream and downstream on-off valves are located relatively close to each other across the partition, a decrease in responsiveness is suppressed in the passive second on-off valve. As a result, the seal member can be protected while ensuring gas fuel injection performance.

[0010] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a longitudinal sectional view of a fuel injection valve, Fig. 2 is a perspective view of a second cylindrical portion, Fig. 3 is an enlarged longitudinal sectional view of a nozzle body and a lower on-off valve, Fig. 4 is a cross sectional view taken along line 4-4 in Fig. 3, Fig. 5 is a perspective view of the lower on-off valve, Fig. 6 is a longitudinal sectional view showing the fuel injection valve in an open state, Fig. 7 is an enlarged longitudinal sectional view of the nozzle body and the lower on-off valve in another example, and Fig. 8 is a longitudinal sectional view showing the configuration of a fuel injection valve in another example.

[0011] Hereinafter, one embodiment of a gas fuel injection valve according to the present disclosure will be described 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 any of hydrogen, CNG (Compressed Natural Gas), and LNG (Liquefied Natural Gas) as gas fuel, 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 engine mounted on a vehicle. The fuel injection system of this embodiment is a so-called low-pressure direct injection system in which gas fuel compressed to about several MPa is injected into the combustion chamber from the fuel injection valve.

[0012] The configuration of a fuel injection valve 10 will be described using Figure 1. In the following description, an axis extending in the longitudinal direction of the fuel injection valve 10 and at the center of a cross section thereof is used as a reference, and the direction in which the axis extends is referred to as the axial direction, the direction extending radially from the axis is referred to as the radial direction, and the direction extending circumferentially around the axis is referred to as the circumferential direction. In Figure 1, the right side is referred to as the base end side (upstream side) of the fuel injection valve 10, and the left side is referred to as the tip side (downstream side).

[0013] The fuel injection valve 10 generally includes a housing 11, a nozzle body 12 located distally of the housing 11, an upper on-off valve 13 reciprocally mounted within the housing 11, and a lower on-off valve 14 reciprocally mounted within the nozzle body 12. The upper on-off valve 13 is an active upstream on-off valve that opens by electromagnetic actuation, while the lower on-off valve 14 is a passive downstream on-off valve that opens in response to a pressure difference between the upstream and downstream sides. In the fuel injection valve 10, the lower on-off valve 14 opens in response to the opening of the upper on-off valve 13, and gas fuel is injected from an injection hole 15 by the opening of these on-off valves 13, 14. The housing 11 and the nozzle body 12 correspond to a "main body," the upper on-off valve 13 corresponds to a "first on-off valve," and the lower on-off valve 14 corresponds to a "second on-off valve."

[0014] Although not shown because it is a well-known configuration, the fuel injection valve 10 is mounted on the gas engine so that its tip (nozzle body 12) is exposed inside the combustion chamber, and the fuel injection valve 10 directly injects gas fuel into the combustion chamber. The configuration of each part of the fuel injection valve 10 will be described in detail below.

[0015] The housing 11 is cylindrical, and a fixed core 21 is fixed within its hollow portion. The upper stage on-off valve 13 is accommodated in a reciprocating manner in a position aligned with the fixed core 21 in the axial direction. The upper stage on-off valve 13 is made of a movable core. The fixed core 21 is cylindrical, and a first spring 22 made of a compression coil spring is disposed inside the fixed core 21. The first spring 22 is provided between a spring bearing portion 21 a of the fixed core 21 and an axial end face of the upper stage on-off valve 13. The first spring 22 biases the upper stage on-off valve 13 toward the tip end side of the fuel injection valve 10 (i.e., in a direction that closes a communication hole 34, described below, from the base end side).

[0016] The fixed core 21 has a hollow portion 21b, and the upper stage on-off valve 13 has a hollow portion 13a. These hollow portions 21b, 13a extend in the axial direction and are in communication with each other. When gas fuel is supplied from a fuel pipe provided closer to the base end than the fixed core 21, the gas fuel is introduced to the tip end side of the upper stage on-off valve 13 through an upstream fuel passage P1 made up of the hollow portions 21b, 13a of the fixed core 21 and the upper stage on-off valve 13. In this embodiment, for example, hydrogen gas is used as the gas fuel, and the gas fuel compressed to about 3 MPa is introduced into the fuel passage P1.

[0017] A coil 25 is provided in the housing 11 as a drive unit for the fuel injection valve 10. An energization signal is input to the coil 25 from a power supply device (not shown) via a harness 26. When the coil 25 is energized, magnetic energy is generated, and the magnetic energy displaces the upper on-off valve 13 toward the valve opening side against the biasing force of the first spring 22.

[0018] The nozzle body 12 is provided downstream of the upper stage on-off valve 13. The nozzle body 12 has a first cylindrical portion 31 at the tip end and a second cylindrical portion 32 at the base end, with the inner periphery of each of these cylindrical portions 31, 32 forming a downstream fuel passage P2. One axial end of the first cylindrical portion 31 forms the injection hole 15. The second cylindrical portion 32 has an end plate portion 33 provided at the base end. A plurality of communication holes 34 extending in the axial direction are formed in the end plate portion 33. The end plate portion 33 is a partition portion that separates the upstream fuel passage P1 formed by the fixed core 21 and the upper stage on-off valve 13 from the downstream fuel passage P2 formed by the nozzle body 12 in the fuel injection valve 10. The communication holes 34 are communication passages that connect these upstream and downstream fuel passages P1, P2. The end plate portion 33 is a pressure partition that prevents the pressure generated by combustion in the engine combustion chamber from propagating to the upstream fuel passage P1.

[0019] 2 is a perspective view of the second tubular portion 32. As shown in FIG. 2, the second tubular portion 32 has a peripheral wall portion 35 extending downstream (to the left in the figure) on the outer periphery of the end plate portion 33. The end plate portion 33 also has a plurality of communication holes 34 formed circumferentially along the peripheral wall portion 35. Each of the communication holes 34 is formed in an arc shape extending in the circumferential direction. However, the opening shape of each communication hole 34 may be any shape, and may be, for example, circular.

[0020] Returning to the description of FIG. 1 , annular plate-shaped seal members 27 are fixed to the axial end face of the upper stage on-off valve 13 at positions facing the openings of each communication hole 34. When the upper stage on-off valve 13 is closed by the biasing force of the first spring 22 (the state shown in FIG. 1 ), the seal member 27 abuts against a seat surface 33a, which is the axial end face of the end plate portion 33, and the seal member 27 closes the first openings, which are the upstream openings of the communication holes 34. When the upper stage on-off valve 13 is displaced to the valve opening side, the seal member 27 moves away from the seat surface 33a of the end plate portion 33, and the first openings are opened. The seal member 27 is made of any elastic material, such as rubber, resin, or elastomer. More specifically, fluororubber, EPDM (ethylene propylene diene rubber), or the like, is preferably used as the seal material.

[0021] A lower stage on-off valve 14 is provided within the nozzle body 12 to open and close the communication hole 34 from the fuel passage P2 side. The lower stage on-off valve 14 has a cylindrical portion 41 and a flange-shaped opening closing portion 42 that is provided at one axial end of the cylindrical portion 41 and extends radially. The cylindrical portion 41 is a sliding portion that can slide axially along the inner circumferential surface of the first tubular portion 31, and the opening closing portion 42 is a closing plate portion that closes the second opening, which is the downstream opening of the communication hole 34. The opening closing portion 42 can be lifted between a position that closes the second opening (downstream opening) of the communication hole 34 and a position that opens it. In this embodiment, the opening closing portion 42 has an annular plate shape and is provided so as to extend radially outward from the cylindrical portion 41.

[0022] A second spring 45 made of a compression coil spring is disposed between the opening closing portion 42 and the axial end face of the first cylindrical portion 31. The second spring 45 biases the lower stage on-off valve 14 toward the base end of the fuel injection valve 10 (i.e., in a direction to close the communication hole 34 from the tip end). The lower stage on-off valve 14 opens when the pressure in the communication hole 34 becomes greater than the biasing force of the second spring 45. The second spring 45 corresponds to the "biasing member."

[0023] The lower valve 14 may be made of a heat-resistant metal, non-metal, or other non-elastomeric material. The opening closing portion 42 is pressed against the downstream opening of the communication hole 34, thereby preventing the gas fuel from leaking from the communication hole 34 and also preventing the inflow of flames and combustion pressure into the combustion chamber.

[0024] In the end plate portion 33, the communication hole 34 is closed from one axial side, i.e., the fuel passage P1 side, by the upper stage on-off valve 13, and the communication hole 34 is closed from the other axial side, i.e., the fuel passage P2 side, by the lower stage on-off valve 14. The upper stage on-off valve 13 is an inward opening valve that opens toward the base end of the fuel injection valve 10, and the lower stage on-off valve 14 is an outward opening valve that opens toward the tip end of the fuel injection valve 10.

[0025] In the fuel injection valve 10, when the upper on-off valve 13 is displaced to the valve-opening side as a result of energization of the coil 25, gas fuel in the upstream fuel passage P1 flows into the communication hole 34, and the pressure in the communication hole 34 increases. When the pressure in the communication hole 34 exceeds the biasing force of the second spring 45, the lower on-off valve 14 is displaced to the valve-opening side. In this case, when the on-off valves 13, 14 on both sides of the communication hole 34 are both in the open state, gas fuel flows from the upstream fuel passage P1 to the downstream fuel passage P2, and the gas fuel is further injected from the injection hole 15 at the tip of the fuel passage P2.

[0026] In the fuel injection valve 10 of this embodiment, after the upper stage on-off valve 13 is closed, gas fuel remains in the communication hole 34 provided in the end plate portion 33 until the next opening of the upper stage on-off valve 13. In this case, the total volume of the multiple communication holes 34 provided in the end plate portion 33 is the residual gas volume remaining downstream of the upper stage on-off valve 13 after the upper stage on-off valve 13 is closed, until the next opening of the upper stage on-off valve 13.

[0027] Next, a detailed description will be given of the configuration related to the outflow of gas fuel from the communication hole 34 when the lower stage on-off valve 14 is opened. Fig. 3 is an enlarged longitudinal cross-sectional view of the nozzle body 12 and the lower stage on-off valve 14, and Fig. 4 is a transverse cross-sectional view taken along line 4-4 in Fig. 3. In Fig. 4, the communication hole 34 of the end plate portion 33 is indicated by a dashed line. Fig. 5 is a perspective view of the lower stage on-off valve 14.

[0028] As shown in FIG. 3 , in the nozzle body 12, the inner periphery of the first cylindrical portion 31 is formed with a sliding surface 36 along which the cylindrical portion 41 of the lower stage on-off valve 14 slides, and the inner periphery of the first cylindrical portion 31 and the second cylindrical portion 32 is formed with an expanded-diameter inner periphery 37 that is larger in diameter than the sliding surface 36. As a result, the inner periphery of the peripheral wall portion 35 forms an expansion space S1 that expands radially outward at the most upstream portion of the fuel passage P2 (i.e., a predetermined range on the most upstream side). In other words, the passage diameter dimension differs between the most upstream portion and the downstream side of the fuel passage P2 in the nozzle body 12, and the passage diameter dimension is expanded at the most upstream portion, thereby forming an annular expansion space S1. In terms of its relationship to the lower stage on-off valve 14, the expansion space S1 is formed radially outward of the cylindrical portion 41.

[0029] The second spring 45 is housed in the expansion space S1. The expanded inner circumferential surface 37 and the expansion space S1 formed by the expanded inner circumferential surface 37 may be formed by the first cylindrical portion 31 and the second cylindrical portion 32, or may be formed by only the second cylindrical portion 32, as long as the expanded inner circumferential surface 37 is located downstream of the end plate portion 33 in the nozzle body 12.

[0030] Furthermore, a protrusion 38 protruding toward the downstream side is provided at the center of the downstream end face of the end plate portion 33. The protrusion 38 is provided radially inward of the peripheral wall portion 35, and more specifically, is provided radially inward of the cylindrical portion 41 of the lower on-off valve 14 on the radially inner side of the peripheral wall portion 35. The protrusion 38 is formed in a conical shape. However, the shape of the protrusion 38 is arbitrary and may be cylindrical, prismatic, pyramidal, or the like, and multiple protrusions 38 may be provided. The peripheral wall portion 35 and the protrusion 38 correspond to the "extension portion."

[0031] 4 , if the outer diameter dimension of the cylindrical portion 41 of the lower stage on-off valve 14 (in other words, the inner diameter dimension of the sliding surface 36 of the first cylindrical portion 31) is D1, the inner diameter dimension of the expanded inner circumferential surface 37 is D2, and the outer diameter dimension of the opening closing portion 42 of the lower stage on-off valve 14 is D3, these dimensions have a relationship of D1<D3, D2>D3. In other words, the inner diameter dimension D2 of the expanded inner circumferential surface 37 is larger than the outer diameter dimension D1 of the cylindrical portion 41 (the inner diameter dimension of the sliding surface 36), thereby forming an expansion space S1. Furthermore, the inner diameter dimension D2 of the expanded inner circumferential surface 37 is larger than the outer diameter dimension D3 of the opening closing portion 42, thereby enabling the formation of a radial gap between the expanded inner circumferential surface 37 and the outer periphery of the opening closing portion 42.

[0032] Therefore, when the lower on-off valve 14 is displaced to the open position, the gas fuel flowing downstream from the communication hole 34 flows radially outward and radially inward through the gap between the downstream end face of the end plate portion 33 and the opening closure portion 42. That is, the opening closure portion 42 has a portion that protrudes radially outward and a portion that protrudes radially inward from the opening of the communication hole 34, and these protruding portions guide the gas fuel flowing from the communication hole 34 radially inward and outward, respectively. The opening closure portion 42 corresponds to a "guide portion." At this time, the gas fuel flowing radially outward proceeds to collide with the expanded-diameter inner circumferential surface 37 (the inner circumferential surface of the peripheral wall portion 35) and is introduced into the expansion space S1 through the gap between the expanded-diameter inner circumferential surface 37 and the outer periphery of the opening closure portion 42. Meanwhile, the gas fuel flowing radially inward proceeds to collide with the protrusion 38 of the end plate portion 33.

[0033] Furthermore, a plurality of openings 43 are provided at predetermined intervals in the circumferential direction in the cylindrical portion 41 of the lower on-off valve 14 (see FIG. 5 ). Therefore, the openings 43 communicate with the inside and outside of the cylindrical portion 41, i.e., the expansion space S1 and the inner space located radially inside the expansion space S1.

[0034] Fig. 6 is a diagram for explaining the flow of gas fuel when the fuel injection valve 10 is open. In Fig. 6, the upper and lower on-off valves 13, 14 of the fuel injection valve 10 are both open, and the flow of gas fuel is indicated by arrows.

[0035] When the opening closing portion 42 moves away from the downstream end face (downstream seat surface) of the end plate portion 33 when the lower on-off valve 14 is opened, gas fuel flows out from the communication hole 34, and at this time, the temperature of the gas fuel drops due to adiabatic expansion of the gas fuel. Specifically, in a gas engine, gas fuel is injected from the fuel injection valve 10 during at least one of the intake stroke and the compression stroke, and at the time of fuel injection, when the gas fuel flows out from the communication hole 34 as the lower on-off valve 14 opens, the pressure of the gas fuel is reduced from several MPa to near atmospheric pressure. For example, when the gas supply pressure is 2 MPa or higher, it is thought that the gas temperature will drop by 100°C or more due to adiabatic expansion.

[0036] The gas fuel flowing out of the communication hole 34 strikes the flat-plate-shaped opening closure portion 42 and flows downward, splitting into two directions, radially outward and radially inward. That is, the gas fuel flowing out of the communication hole 34 is guided radially outward and radially inward by the opening closure portion 42 of the lower on-off valve 14. The gas fuel guided radially outward collides with the inner circumferential surface of the peripheral wall portion 35 and then flows downstream through the fuel passage P2 via the expansion space S1 and the opening 43 of the lower on-off valve 14. At this time, the gas fuel, whose temperature has decreased due to adiabatic expansion when it flowed out of the communication hole 34, is introduced into the expansion space S1, thereby promoting heat exchange within the expansion space S1. This promotes cooling of the end plate portion 33 and suppresses a temperature rise in the seal member 27. In particular, the gas fuel is guided radially outward immediately after flowing out of the communication hole 34, then changes direction of flow radially inward, and its path meanders radially. Therefore, heat exchange with the second cylindrical portion 32 is promoted.

[0037] The expansion space S1 is provided with a second spring 45, which is cooled by the gas fuel whose temperature has been reduced by adiabatic expansion. This reduces the thermal load on the second spring 45, which is exposed to the flames in the engine combustion chamber.

[0038] Furthermore, the gas fuel guided radially inward after the lower on-off valve 14 opens collides with the protrusion 38 at the center of the end plate 33. As a result, the end plate 33 is cooled by the adiabatically expanded gas fuel, and the temperature rise of the seal member 27 is suppressed.

[0039] According to the present embodiment described above in detail, the following excellent effects can be obtained.

[0040] In the fuel injection valve 10, a seal member 27 that seals the periphery of the opening of the communication hole 34 is provided between the upper stage on-off valve 13 and the end plate portion 33. This makes it possible to improve gas sealing performance compared to a configuration in which the upper stage on-off valve 13 and the end plate portion 33 are in direct contact when the upper stage on-off valve 13 is in a closed state.

[0041] Furthermore, when the gas fuel flows out of the communication hole 34 in response to the opening of the lower stage valve 14, adiabatic expansion of the gas fuel occurs, and the gas fuel, whose temperature is reduced by the adiabatic expansion, cools the end plate 33. This cooling of the end plate 33 also cools the seal member 27, which is located on the opposite side of the end plate 33 from the lower stage valve 14 (the upper stage valve 13 side). Although the seal member 27 is located relatively close to the lower stage valve 14, separated only by the end plate 33, excessive temperature rise of the seal member 27 is suppressed. Furthermore, because the upstream and downstream valves 13, 14 are located relatively close to each other across the end plate 33, a decrease in responsiveness of the passive lower stage valve 14 is suppressed. As a result, the seal member 27 can be protected while ensuring gas fuel injection performance.

[0042] A communication hole 34 is provided between the peripheral wall portion 35 and the protruding portion 38 in the end plate portion 33 of the second cylindrical portion 32, and the opening closing portion 42 of the lower on-off valve 14 guides the gas fuel that has flowed out from the communication hole 34 and has been adiabatically expanded radially outward and radially inward, respectively, and causes it to collide with the peripheral wall portion 35 and the protruding portion 38. In this case, the gas fuel whose temperature has been reduced by the adiabatic expansion collides with the peripheral wall portion 35 and the protruding portion 38, respectively, thereby cooling the second cylindrical portion 32. This promotes cooling of the end plate portion 33 and suppresses a temperature rise in the seal member 27.

[0043] According to the configuration of this embodiment, the desired cooling effect is achieved by optimizing the flow direction of the cooling gas (gas fuel after adiabatic expansion) using the lower on-off valve 14, and the sealing member 27 can be properly cooled while using a simple configuration.

[0044] An annular expansion space S1 is formed by expanding the passage diameter dimension at the most upstream side of the fuel passage P2 in the nozzle body 12, and the opening closing portion 42 of the lower on-off valve 14 guides the gas fuel flowing out from the communication hole 34 toward the expansion space S1. In this case, the gas fuel, whose temperature has been reduced by adiabatic expansion when the lower on-off valve 14 is opened, is introduced into the expansion space S1, thereby promoting heat exchange within the expansion space S1. This promotes cooling of the end plate portion 33 and suppresses a temperature rise in the seal member 27.

[0045] The cylindrical portion 41 of the lower stage on-off valve 14 is provided with an opening 43 that communicates with the expansion space S1 and an inner space located radially inside the expansion space S1. In this case, the gas fuel, whose temperature has been reduced by adiabatic expansion when the lower stage on-off valve 14 is opened, flows through a path in which it is introduced into the expansion space S1 and then proceeds to the inner space via the opening 43 of the cylindrical portion 41. This causes the gas fuel to meander radially within the fuel passage P2, facilitating heat exchange with the second cylindrical portion 32.

[0046] A second spring 45 that biases the lower on-off valve 14 toward the valve closing side is provided in the expansion space S1. In this case, the second spring 45 is cooled by the gas fuel whose temperature has decreased due to adiabatic expansion. This makes it possible to reduce the thermal load on the second spring 45 that is exposed to the flames in the engine combustion chamber.

[0047] The total volume of the plurality of communication holes 34 provided in the end plate portion 33 of the second cylindrical portion 32 is configured to be the residual gas volume remaining downstream of the upper on-off valve 13 after the upper on-off valve 13 closes and until the next time the upper on-off valve 13 opens. In other words, the end plate portion 33 needs only to have a thickness sufficient to separate the upstream and downstream fuel passages P1, P2 and to withstand pressure waves from the engine combustion chamber, and only the volume of the communication holes 34 corresponding to that thickness is the residual gas volume downstream of the upper on-off valve 13. In this case, unlike existing separate structures in which a spring or the like is interposed between the upper on-off valve 13 and the lower on-off valve 14, it is possible to reduce the residual gas volume and thereby improve the responsiveness of the fuel injection valve 10.

[0048] (Other Embodiments) The above embodiment may be modified as follows, for example.

[0049] In the above embodiment, the peripheral wall portion 35 and the protruding portion 38 of the nozzle body 12 are the targets (extending portions) against which the adiabatically expanded gas fuel collides. However, this configuration may be modified. For example, only the peripheral wall portion 35 may be the target (extending portion) against which the adiabatically expanded gas fuel collides. Specifically, as shown in FIG. 7 , the opening closing portion 42 of the lower on-off valve 14 is configured to be a disk-shaped portion without a central opening, and the protruding portion 38 of the end plate portion 33 is eliminated. In this case, the opening closing portion 42 of the lower on-off valve 14 guides the adiabatically expanded gas fuel that has flowed out of the communication hole 34 radially outward and collides with the peripheral wall portion 35. This cools the peripheral wall portion 35 and the end plate portion 33, thereby suppressing a temperature rise in the seal member 27.

[0050] The fuel injection valve 10 may be configured as shown in Figure 8. In Figure 8, the main body is a cylindrical body, and an end plate portion 33 (partition portion) is fixed to the middle portion of the body. Figure 8 shows a state in which both the upper on-off valve 13 and the lower on-off valve 14 are open.

[0051] 8 , a communication hole 34 is provided in the center of a disk-shaped end plate 33, and the communication hole 34 is opened and closed from the upstream side by the upper on-off valve 13 and from the downstream side by the lower on-off valve 14. The lower on-off valve 14 is biased by a second spring 45 in a direction to close the downstream opening of the communication hole 34. In this configuration, as in the above, the lower on-off valve 14 guides the gas fuel that has flowed out of the communication hole 34 and adiabatically expanded radially outward, and the collision between the gas fuel and the peripheral wall 35 cools the peripheral wall 35 and the end plate 33, thereby suppressing a temperature rise in the seal member 27. Note that the surface of the lower on-off valve 14 that faces the end plate 33 corresponds to the "guide portion."

[0052] In the above embodiment, the seal member 27 is provided between the upper stage on-off valve 13 and the end plate portion 33 by fixing the seal member 27 to the axial end surface of the upper stage on-off valve 13. However, this may be modified. For example, the seal member 27 may be fixed to the end plate portion 33 side.

[0053] A motor may be used instead of the coil 25 as a drive unit for driving the upper stage on-off valve 13 .

[0054] The technical concepts extracted from the above-described embodiments are described below. [Configuration 1] A gas fuel injection valve (10) for directly injecting gas fuel into a combustion chamber of an internal combustion engine, comprising: a main body (11, 12) having a cylindrical shape, a fuel passage therein, and an injection hole (15) at a tip end thereof, the main body having a partitioning portion (33) for partitioning the fuel passage into a first fuel passage (P1) on an upstream side and a second fuel passage (P2) on a downstream side, the partitioning portion having a communication hole (34) for communicating the first fuel passage with the second fuel passage, the main body being provided with a first on-off valve (13) for opening and closing the communication hole from the first fuel passage side, a second on-off valve (14) for opening and closing the communication hole from the second fuel passage side, and a seal member (27) for sealing the periphery of the opening of the communication hole between the first on-off valve and the partitioning portion, The first on-off valve is driven to open by a drive unit (25), while the second on-off valve is opened when the pressure in the communication hole becomes higher than the biasing force of a biasing member (45) that biases the second on-off valve toward the valve closing side, and the gas fuel injection valve is configured so that when the second on-off valve opens, the gas fuel that flows out of the communication hole and adiabatically expands collides with an extension portion (35, 38) extending downstream from the partition portion, thereby cooling the extension portion. [Configuration 2] The gas fuel injection valve according to Configuration 1, wherein the main body portion has a peripheral wall portion (35) extending downstream from an outer periphery of the partition portion and forming the second fuel passage, and a protrusion portion (38) protruding downstream from a downstream end face of the partition portion at a position radially inward of the peripheral wall portion, the peripheral wall portion and the protrusion portion being the extension portion, the partition portion having the communication hole between the peripheral wall portion and the protrusion portion, and the second on-off valve having a guide portion (42) that guides the gas fuel that has flowed out of the communication hole and adiabatically expanded radially outward and radially inward, respectively, and causes it to collide with the peripheral wall portion and the protrusion portion. [Configuration 3] The gas fuel injection valve according to Configuration 1, wherein the main body portion has a peripheral wall portion (35) extending downstream from an outer periphery of the partition portion and forming the second fuel passage, the peripheral wall portion being the extension portion, and the second on-off valve has a guide portion (42) that guides the gas fuel that has flowed out of the communication hole and adiabatically expanded radially outward and causes it to collide with the peripheral wall portion.[Configuration 4] The gas fuel injection valve according to Configuration 2 or 3, wherein the passage diameter dimension of the second fuel passage is different between the most upstream portion and the downstream side thereof in the main body portion, and the passage diameter dimension is expanded in the most upstream portion to form an annular expansion space (S1), and the guide portion of the second on-off valve guides the gas fuel that has flowed out of the communication hole and adiabatically expanded radially outward to introduce it into the expansion space. [Configuration 5] The gas fuel injection valve according to Configuration 4, wherein the second on-off valve has a cylindrical portion (41) that is slidable against the inner circumferential surface of the main body portion, and the expansion space is formed radially outward of the cylindrical portion, and the cylindrical portion has an opening (43) that communicates the expansion space with an inner space radially inside the cylindrical portion. [Configuration 6] The gas fuel injection valve according to Configuration 4 or 5, wherein the expansion space is provided with a biasing member (45) that biases the second on-off valve to a valve closing side. [Configuration 7] The gas fuel injection valve according to any one of Configurations 1 to 6, wherein a total volume of the plurality of communication holes provided in the partition portion is a residual gas volume remaining downstream of the first on-off valve after the first on-off valve is closed until the first on-off valve is opened again.

[0055] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A gas fuel injection valve (10) for directly injecting gas fuel into a combustion chamber of an internal combustion engine, comprising a body portion (11, 12) having a cylindrical shape, a fuel passage therein, and an injection hole (15) at a tip portion, the body portion having a partition portion (33) for partitioning the fuel passage into a first fuel passage (P1) on the upstream side and a second fuel passage (P2) on the downstream side, the partition portion having a communication hole (34) for communicating the first fuel passage with the second fuel passage, the body portion being provided with a first opening / closing valve (13) for opening and closing the communication hole from the first fuel passage side, a second opening / closing valve (14) for opening and closing the communication hole from the second fuel passage side, and a seal member (27) for sealing the periphery of the opening of the communication hole between the first opening / closing valve and the partition portion, The first opening / closing valve is driven to open by a drive portion (25), while the second opening / closing valve is opened when the pressure in the communication hole becomes higher than the biasing force of a biasing member (45) that biases the second opening / closing valve to a closing side, and the gas fuel injection valve is configured so that when the second opening / closing valve is opened, the gas fuel that flows out of the communication hole and undergoes adiabatic expansion is caused to collide with an extension portion (35, 38) extending downstream from the partition portion, thereby cooling the extension portion.

2. A gas fuel injection valve as described in claim 1, wherein the main body portion has a peripheral wall portion (35) extending downstream from an outer periphery of the partition portion and forming the second fuel passage, and a protrusion portion (38) protruding downstream at a position radially inward of the peripheral wall portion on the downstream end face of the partition portion, these peripheral wall portion and protrusion portion being the extension portion, the partition portion has the communication hole between the peripheral wall portion and the protrusion portion, and the second opening / closing valve has a guide portion (42) that guides the gas fuel that has flowed out of the communication hole and has been adiabatically expanded radially outward and radially inward, respectively, and causes it to collide with the peripheral wall portion and the protrusion portion.

3. A gas fuel injection valve as described in claim 1, wherein the main body portion has a peripheral wall portion (35) extending downstream from the outer periphery of the partition portion and forming the second fuel passage, the peripheral wall portion being the extension portion, and the second opening / closing valve has a guide portion (42) that guides the gas fuel that has flowed out of the communication hole and has been adiabatically expanded radially outward and causes it to collide with the peripheral wall portion.

4. A gas fuel injection valve as described in claim 2 or 3, wherein in the main body, a passage diameter dimension differs between the upstream-most portion and the downstream side of the second fuel passage, and the passage diameter dimension is expanded in the upstream-most portion to form an annular expansion space (S1), and the guide portion of the second opening / closing valve guides the gas fuel that has flowed out of the communication hole and adiabatically expanded radially outward and introduces it into the expansion space.

5. A gas fuel injection valve as described in claim 4, wherein the second opening / closing valve has a cylindrical portion (41) that is slidable against the inner surface of the main body portion, the expansion space is formed radially outward of the cylindrical portion, and the cylindrical portion has an opening (43) that communicates with the expansion space and an inner space radially inward of the expansion space.

6. A gas fuel injection valve as set forth in claim 4, wherein a biasing member (45) for biasing the second opening / closing valve in a valve closing direction is provided in the expansion space.

7. A gas fuel injection valve as described in claim 1, wherein the total volume of the multiple communicating holes provided in the partition portion is the residual gas volume remaining downstream of the first opening / closing valve after the first opening / closing valve is closed until the first opening / closing valve is opened again.

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